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Digitized by the Internet Archive
in 2007 with funding from
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http://www.archive.org/details/anatdescsurgiOOgrayrich
*4?
TO
SIR BENJAMIN COLLINS BRODIE, BART,.F.R.S, D.C.L,
SERJEANT-SURGEON TO THE QUEEN,
CORRESPONDING MEMBER OF THE INSTITUTE OF FRANCE,
fflfis Mark is $*tattbt
IN ADMIRATION OF HIS GREAT TALENTS,
IN REMEMBRANCE OF MANY ACTS OF KINDNESS
SHOWN TO THE AUTHOR,
FROM AN EARLY PERIOD OF HIS PROFESSIONAL CAREER.
BQS&k
(in)
AMERICAN PUBLISHERS' NOTICE.
The present edition, like the last American reprint, has been passed
through the press under the supervision of Dr. Richard J. Dunglison,
who has carefully corrected whatever errors had escaped the attention of
the author, and has made such changes in the typographical arrangement
as seemed calculated to render the volume more convenient for consulta-
tion and reference.
February, 1862.
( iv )
PREFACE.
In preparing a Second Edition of my " Descriptive and Surgical
Anatomy," I trust that I have corrected any inaccuracies contained in
the previous one ; every page has been carefully revised ; much addi-
tional matter has been added to the text; and several new Illustrations,
executed with great care and fidelity by Dr. Westmacott, have been
inserted.
December, 1860.
(v)
viii PREFACE.
The Veins are described as in ordinary anatomical works; and illustrated by a
series of engravings, showing those in each region. The veins of the spine are
described and illustrated from the well-known work of Breschet.
The Lymphatics are described, and figured in a series of illustrations copied
from the elaborate work of Mascagni.
Tlie Nervous System and Organs of Sense. A concise and accurate description of
this important part of anatomy has been given, illustrated by sixty-six engravings,
showing the spinal cord and its membranes ; the anatomy of the brain, in a series
of sectional views; the origin, course, and distribution of the cranial, spinal, and
sympathetic nerves; and the anatomy of the organs of sense.
The Viscera. A detailed description of this essential part of anatomy has been
given, illustrated by fifty-five large, accurately-lettered engravings.
Regional Anatomy. The anatomy of the perineum, of the ischio-rectal region,
and of femoral and inguinal hernia, is described at the end of the work; the
region of the neck, the axilla, the bend of the elbow, Scarpa's triangle, and the
popliteal space, in the section on the arteries; the laryngo-tracheal region, with
the anatomy of the trachea and larynx. The regions are illustrated by many
engravings.
Microscopical Anatomy. A brief account of the microscopical anatomy of some
of the tissues, and of the various organs, has also been introduced.
The Author gratefully acknowledges the great services he has derived in the
execution of this work, from the assistance of his friend, Dr. H. V. Carter, late
Demonstrator of Anatomy at St. George's Hospital. All the drawings from which
the engravings were made, were executed by him. In the majority of cases, they
have been copied from, or corrected by, recent dissections made jointly by the
Author and Dr. Carter.
The Author has also to thank his friend, Mr. T. Holmes, for the able assistance
afforded him in correcting the proof-sheets in their passage through the press.
The engravings have been executed by Messrs. Butterworth and Heath ; and
the Author cannot omit thfanking these gentlemen for the great care and fidelity
displayed in their execution.
Wilton-Street, Belgrave-Squark.
August, 1858.
CONTENTS.
Osteology.
Structure and Physical Properties of
Bone ....
Chemical Composition of Bone
Form of Bones
Surfaces of Bones
Microscopic Structure
Vessels of Bone
Periosteum
Marrow .
Development of Bone
Growth of Bone
Number of Bones
The Spine.
General Characters of a Yertebra .
Characters of the Cervical Vertebrae
Peculiar Cervical Vertebra;
Atlas
Axis
Vertebra Prominens
Characters of the Dorsal Vertebrae
Peculiar Dorsal Vertebrae
Characters of the Lumbar Vertebrae
Structure and Development of the Verte-
brae
Atlas .
Axis .
Seventh Cervical
Lumbar Vertebrae
Progress of Ossification in the Spine
Sacral and Coccygeal Vertebrae
Sacrum
Coccyx
Of the Spine in general .
The Skull.
Division of Bones of
Bones of the Cranium
Occipital Bone .
Parietal Bones .
Frontal Bone .
Temporal Bones
Sphenoid Bone
Sphenoidal Spongy Bones
Ethmoid Bone .
Development of the Cranium
The Fontanelles
"Wormian Bones
Congenital Fissures and Gaps
Bones of the Face .
Nasal Bones
Superior Maxillary Bone .
Lachrymal Bones
Malar Bones
Palate Bones
33
33
34
35
36
37
:is
38
38
•Id
40
40
41
42
42
43
44
44
45
47
47
49
49
49
49
49
50
50
54
55
57
57
57
Gl
83
(17
72
7(1
77
79
79
80
80
so
Bl
83
86
87
88
PAOB
Inferior Turbinated Bones . . 91
Vomer ....
92
Inferior Maxillary Bone .
92
Changes produced by age
95
Sutures of the Skull
97
Vertex of the Skull
98
Base of the Skull, Internal Surface
. 100
Anterior Fossae .
100
Middle Fossae
. 100
Posterior Fossae .
. 101
Base of Skull, External Surface
. 102
Lateral Kegion of the Skull
105
Temporal Fossae
. 105
Zygomatic Fossae
. 106
Spheno-maxillary Fossae .
. 106
Anterior Begion of Skull
. 106
Orbits
108
Nasal Fossae ....
. 109
Os Hyoides ....
111
The Thorax.
The Sternum . . . . . 112
Development of the Sternum
. 114
The Ribs ....
. 116
Peculiar Ribs .
- 118
Costal Cartilages
. 120
The Upper Extremity.
The Clavicle 121
Development of the Clavicle
123
The Scapula
123
Development of the Scapula
The Humerus .
127
129
Development of the Humerus
133
The Forearm .
133
The Ulna
133
The Radius
138
The Hand
140
The Carpus
140
Bones of Upper Row
141
Bones of Lower Row
143
The Metacarpus
146
Peculiar Metacarpal Bones
146
Phalanges
147
Development of the Hand
148
The Lower Extremity.
Os Innominatum 149
149
Pubes
153
Development of the Os Innominatum
154
The Pelvis
155
Boundaries of Pelvis ....
155
(
ix)
CONTENTS.
Position of Pelvis
Axes of Pelvis .....
Differences between the Male and Female
Pelvis
The Femur
Development of the Femur
The Leg
Patella .......
Tibia
Development of Tibia ....
Fibula
Development of Fibula ....
The Foot
PAGE
157 Tarsus ....
157 Oalcaneum or Os Calcis .
Cuboid ....
158 Astragalus
158 Scaphoid ....
163 Internal Cuneiform .
163 Middle Cuneiform .
164 External Cuneiform
165 j Metatarsal Bones
168 j Peculiar Metatarsal Bones
168 j Phalanges
170 Development of the Foot
170 i Sesamoid Bones
PAGE
170
170
173
173
175
175
176
176
177
177
178
178
179
The Articulations.
General Anatomy of the Joints . . 181
Cartilage 181
Fibro-cartilage 183
Ligament 183
Synovial Membrane .... 183
Synovia . . . . . . 184
Forms of Articulation .... 184
Synarthrosis 184
Amphiarthrosis 185
Diarthrosis 185
Movements of Joints .... 187
Gliding Movement .... 187
Angular Movement .... 187
Circumduction 187
Potation 187
Articulations of the Trunk.
Articulations of the Vertebral Column . 188
Atlas with the Axis . 191
Spine with Cranium 194
Temporo-maxillary Articulation . . 195
Articulation of the Ribs with the Verte-
brae 197
Articulations of the Cartilages of the
Ribs with the Sternum . . . 200
Ligaments of the Sternum . . . 202
Articulations of the Pelvis with the Spine 203
Inter-pubic 205
Articulations of the Upper Extremity.
Sterno-clavicular 207
Scapuloclavicular 208
Ligaments of the Scapula . . . 210
Shoulder-joint 210
Elbow-joint 211
Radio-ulnar Articulation .... 213
Wrist-joint 216
Articulations of the Carpus . . .217
Carpo-metacarpal Articulations . . 218
Metacarpo-phalangeal Articulations . 220
Articulation of the Phalanges . . . 220
Articulations of the Lower Extremity.
Hip-joint 221
Knee-joint 223
Articulation between the Tibia and Fibula 226
Ankle-joint 228
Articulations of the Tarsus . . . 229
Tarso-metatarsal Articulations . .233
Articulations of the Metatarsus . . 233
Metatarso-phalangeal Articulations . 233
Articulation of the Phalanges . . . 234
Muscles and Fascia3.
General Anatomy of Muscle .
Tendons .
Aponeuroses .
Fasciae .
Muscles and Fasciae op the Head
and Face.
Subdivision into Groups ....
Epicranial Region.
235
237
237
237
238
Dissection
Occipito-frontalis ....
. 239
. 240
Auricular Region.
Dissection
Attollens Aurem ....
Attrahens Aurem ....
Retrahens Aurem ....
Actions
. 241
. 241
. 242
. 242
. 242
Palpebral Region.
Dissection
Orbicularis Palpebrarum .
. 242
. 242
Corrugator Supercilii
Tensor Tarsi .
Actions .
Orbital Region.
Dissection
Levator Palpebrae Superioris .
Rectus Superior, Inferior, Internal and
External
Superior Oblique
Inferior Oblique
Actions
Surgical Anatomy
Nasal Region.
Pyramidalis Nasi
Levator Labii Superioris Alaeque Nasi
Dilator Naris .
Compressor Naris
Narium Minor
Depressor Ahe Nasi
Actions .
243
243
243
243
243
244
245
245
245
245
246
2-1 G
246
246
246
246
246
CONTENTS.
XI
Superior Maxillary Region.
Levator Labii Snperioris
Levator Anguli Oris
Zygomatici
Actions .
Inferior Maxillary Region.
Dissection
Levator Labii Inferioris .
Depressor Labii Inferioris
Depressor Anguli Oris .
Intermaxillary Region.
Dissection
Orbicularis Oris
Buccinator
Eisorius .
Actions .
Temporo- Maxillary Region.
Masseter
Temporal Fascia ....
Dissection of Temporal Muscle
Temporal
Pterygo-Maxillary Region.
Dissection
Internal Pterygoid ....
External Pterygoid ....
Actions
Muscles and Fasciae of the Neck.
Subdivision into Groups ....
Superficial Cervical Region.
Dissection
Superficial Cervical Fascia
Platysma Myoides ....
Deep Cervical Fascia
Sterno-cleido-mastoid
Boundaries of the Triangles of the Neck
Surgical Anatomy ....
Actions
Infra-hyoid Region.
Dissection ....
Sterno-hyoid ....
Sterno-thyroid ....
Thyro-hyoid, Omo-hyoid .
Actions
PAC1E
247
247
247
247
247
247
248
248
248
248
249
249
249
249
250
250
251
251
251
252
252
252
253
253
253
254
254
255
256
256
256
256
257
258
258
Supra-hyoid Region.
Dissection
Digastric
Stylo-hyoid, Mylo-hyoid, Genio-hyoid
Actions
Lingual Region.
Dissection ....
Genio-hyo-glossus, Hyo-glossus
Stylo-glossus, Lingualis .
Palato-glossus ....
Actions
Pharyngeal Region.
Dissection
Inferior Constrictor
Middle Constrictor, Superior Constrictor
Stylo-pharyngeus
Actions
258
259
259
260
260
260
261
262
262
262
262
263
263
264
Palatal Region.
Dissection ....
Levator Palati
Tensor Palatfi, Azygos Uvulae .
Palato-glossus, Palato-pharyugeus
Actions, Surgical Anatomy
Anterior Vertebral Region.
Bectus Capitis Anticus Major
Pectus Capitis Anticus Minor
Bectus Lateralis ....
Longus Colli
Lateral Vertebral Region.
Scalenus Anticus, Scalenus Medius
Scalenus Posticus ....
Actions
Muscles and Fascle of the Trunk.
Subdivision into Groups ....
Muscles of the Back.
Subdivision into Layers ....
First Layer.
Dissection
Trapezius
Ligamentum Nuchae
Latissimus Dorsi
Second Layer,
Dissection
Levator Anguli Scapulae
Bhomboideus Minor
Bhomboideus Major
Actions .
Third Layer.
Dissection
Serratus Posticus Superior
Serratus Posticus Inferior
Vertebral Aponeurosis .
Splenius Capitis and Splenius Colli
Actions .
Fourth Layer,
Dissection
Erector Spinae .
Sacyo-lumbalis .
Musculus Accessorius ad Sacro-lumbalem
Cervicalis Ascendens
Longissimus Dorsi .
Transversalis Colli .
Trachelo-mastoid
Spinalis Dorsi, Spinalis Cervicis
Complexus
Biventer Cervicis
Fifth Layer.
Dissection
Semispinalis Dorsi, Semispinalis Colli
Multifidus Spinae ....
Botatores Spinae ....
Supra-spinales
Inter-spinales
Extensor Coccygis, Inter-transversales
Bectus Posticus Major .
Bectus Posticus Minor .
Obliquus Superior ....
Obliquus Inferior ....
Actions
PAdK
264
265
265
265
266
266
267
267
267
268
268
268
269
269
269
269
270
270
272
272
272
273
273
273
273
274
274
274
274
278
276
276
276
276
276
277
277
277
277
277
278
278
278
278
279
279
279
279
279
280
280
280
Xll
CONTENTS.
Muscles of the Abdomen.
Dissection
Obliquus Externus
Obliquus Interims
Transversalis .
Lumbar Fascia
Rectus Abdominis
Pyramidalis, Quadratus Lumborum
Linea Alba, Lineae Semilunares
Linear Transversa? .
Actions
PAGE
281
281
283
284
285
286
287
287
287
287
Muscles and Fasciae of the Thorax.
Intercostal Fasciae ...... 288
External Intercostals .... 288
Internal Intercostals .... 288
Infra-costales, Triangularis Sterni . . 289
Levatores Costarum .... 289
Actions 289
Diaphragm
Actions
Diaphragmatic Region.
Muscles and Fascia of the Upper
Extremity.
Subdivision into Groups ....
Dissection of Pectoral Region and Axilla
Fasciae of the Thorax ....
Anterior Thoracic Region
Pectoralis Major
Costo-coracoid Membrane
Pectoralis Minor
Subclavius
Actions .
Lateral Thoracic Region.
Serratus Magnus ....
Actions
Deltoid
Action
Acromial Region.
Anterior Scapular Region.
Subscapular Aponeurosis
Subscapularis
Actions
Posterior Scapular Region
Supra-spinous Aponeurosis
Supra-spinatus
Infra-spinous Aponeurosis
Infra-spinatus .
Teres Minor
Teres Major
Actions ....
Anterior Humeral Region.
Deep Fascia of Arm
< oraco-brachialis, Biceps
Brachialis Anticus ....
Actions
289
292
293
293
294
294
296
296
296
297
298
298
299
299
299
•299
300
300
300
300
300
301
301
302
302
303
304
304
Posterior Humeral Region.
Triceps . . . . . . 304
Subanconeus 304
Actions 304
Muscles of Forearm.
PAOK
Deep Fascia of Forearm . . . 305
Anterior Brachial Region, Superficial
Layer.
Pronator Radii Teres .... 306
. 306
. 307
. 307
. 307
Flexor Carpi Radialis
Palmaris Longus
Flexor Carpi Ulnaris
Flexor Digitorum Sublimis
Anterior Brachial Region, Deep Layer.
Flexor Profundus Digitorum . . . 308
. 309
. 309
. 310
Flexor Longus Poinds
Pronator Quadratus
Actions .
Radial Region.
Dissection
Supinator Longus
Extensor Carpi Radialis Longior
Extensor Carpi Radialis Brevior
310
310
310
311
Posterior Brachial Region, Superficial
Layer.
Extensor Communis Digitorum . . 312
Extensor Minimi Digiti .... 312
Extensor Carpi Ulnaris .... 312
Anconeus 312
Posterior Brachial Region, Deep Layer.
Supinator Brevis ..... 313
Extensor Ossis Metacarpi Pollicis .
. 313
Extensor Primi Internodii Pollicis .
. 313
Extensor Secundi Internodii Pollicis
. 313
Extensor Indicis ....
. 314
. 314
Muscles and Fasciae of the Ham
I.
Dissection
. 315
Anterior Annular Ligament
. 315
Posterior Annular Ligament .
. 315
Palmar Fascia ....
. 316
Muscles of the Hand.
Radial Group
. 316
Ulnar Group
. 318
. 319
Middle Palmar Group
. 319
. 320
Surgical Anatomy of the Muscles q,
f the
Upper Extremity.
Fractures of the Clavicle
. 320
Acromion Process
. 321
Coracoid Process .
. 321
Humerus
. 321
Ulna .
. 322
Olecranon
. 322
Radius .
. 323
Muscles and Fascia of the Low
ER
Extremity.
Subdivision into Groups .
. 324
Iliac Region.
Dissection
. 325
Iliac Fascia
. 325
Psoas Magnus, Psoas Parvus .
. 326
. 326
. 327
CONTENTS.
Xlll
Anterior Femoral Region.
PAGE
327
Fasciae of the Thigh ....
327
Superficial Fascia
327
Deep Fascia, Fascia Lata
328
Saphenous Opening
329
Iliac and Pubic Portions of Fascia Lata .
329
Tensor Vaginas Femoris, Sartorius .
329
Quadriceps Extensor Cruris .
330
Rectus Femoris, Vastus Externus .
330
Vastus Internus and Crureus .
331
331
331
Internal Femoral Region.
332
332
332
Adductor Longus
333
Adductor Brevis, Adductor Magnus
333
334
Gluteal Region.
334
Gluteus Maximus
334
Gluteus Medius
335
Gluteus Minimus
336
Pyriformis ......
336
Obturator Internus, Gemelli .
337
Quadratus Femoris, Obturator Externus
337
338
Posterior Femoral Region.
339
Biceps, Semitendinosus ....
339
Semimembranosus
340
340
Surgical Anatomy of Hamstring Tendons
340
Muscles and Fascia} of Leg.
Dissection of Front of Leg
340
Fascia of the Leg
340
Muscles of the Leg
341
Anterior Tibio-fibular Region.
Tibialis Anticus
341
Extensor Proprius Pollicis
342
Extensor Longus Digitorum .
342
Peroneus Tertius
342
342
Posterior Tibio-fibular Region,
Superficial Layer.
PAGE
Dissection 343
Gastrocnemius 343
Soleus, Tendo Achillis, Plantaris . . 344
Actions 344
Posterior Tibio-fibular Region,
Deep Layer.
Deep Fascia of Leg 345
Popliteus 345
Flexor Longus Pollicis .... 346
Flexor Longus Digitorum, Tibialis Pos-
ticus 346
Actions 347
Fibular Region.
Peroneus Longus 347
Peroneus Brevis 348
Actions 348
Surgical Anatomy of Tendons around
Ankle 348
Muscles and Fascial of Foot.
Anterior Annular Ligament . . . 348
Internal Annular Ligament . . . 349
External Annular Ligament . . . 349
Plantar .Fascia 349
Muscles of the Foot, Dorsal Region.
Extensor Brevis Digitorum . . . 350
Plantar Region.
Subdivision into Groups .
Subdivision into Layers .
First Layer .
Second Layer
Third Layer .
Interossei
350
350
350
352
353
354
Surgical Anatomy of the Muscles of the
Lower Extremity.
Fracture of the Femur .... 353
the Patella . . . .356
the Tibia . . . .356
the Fibula, with Displace-
ment of the Tibia . .357
The Arteries.
General Anatomy.
Subdivision into Pulmonary and Systemic
Distribution of — Where found .
Mode of Division — Anastomoses
Structure of Arteries
Sheath — Vasa Vasorum .
Capillaries ....
Aorta.
Arch of Aorta
Dissection
Ascending Part of Arch .
Transverse Part of Arch .
Descending Part of Arch
Peculiarities
Surgical Anatomy .
Branches ....
Peculiarities of Branches
358
358
358
359
360
360
361
362
363
364
364
364
365
365
Coronary Arteries.
Peculiarities 366
Arteria Innominata.
Relations 366
Peculiarities 366
Surgical Anatomy 367
Common Carotid Arteries.
Course and Relations .... 367
Peculiarities 370
Surgical Anatomy 370
External Carotid Artery.
Relations 371
Surgical Anatomy 372
Branches 372
XIV
CONTENTS.
Superior Thyroid Artery.
Course and Relations
Surgical Anatomy .
Lingual Artery.
Course and Relations
Branches ....
Surgical Anatomy .
Facial Artery,
Course and Relations
Branches ....
Peculiarities
Surgical Anatomy .
Occipital Artery.
Course and Relations
Branches .
PAOE
372
372
373
373
374
374
375
376
376
Posterior Auricular Artery.
376
377
Branches 377
Ascending Pharyngeal Artery.
Branches .
Thyroid Axis .
Supra-scapular Artery
Transversalis Colli .
Internal Mammary .
Superior Intercostal .
Deep Cervical Artery
Surgical Anatomy of the Axilla
Axillary Artery.
First Portion ....
Second Portion
Third Portion ....
Peculiarities, Surgical Anatomy
Branches .
378
378
378
379
Temporal Artery.
Course and Relations
Branches
Surgical Anatomy .
Internal Maxillary Artery.
Course and Relations . 379
Peculiarities ...... 379
Branches from First Portion . '. ' 379
Second Portion . . 381
Third Portion . . .381
Surgical Anatomy of the Triangles of the
Neck.
Anterior Triangular Space.
Inferior Carotid Triangle . . . 333
Superior Carotid Triangle . ." .' 383
Submaxillary Triangle . . '. [ 383
Posterior Triangular Space.
Occipital Triangle . . . 334
Subclavian Triangle . . 334
Internal Carotid Artery.
Cervical Portion
Petrous Portion
Cavernous Portion .
Cerebral Portion
Peculiarities, Surgical Anatomy
Branches
Ophthalmic Artery . . "
Cerebral Branches of Internal Carotid '.
Arteries of the Upper Extremity.
Brachial Artery.
Relations
Bend of the Elbow .
Peculiarities of Brachial Artery
Surgical Anatomy .
Branches
Radial Artery.
Relations
Deep Palmar Arch .
Peculiarities, Surgical Anatomy
Branches
Ulnar Artery.
Relations .....
Superficial Palmar Arch .
Peculiarities of Ulnar Artery .
Surgical Anatomy .
Branches
Descending Aorta
Thoracic Aorta.
Relations
Surgical Anatomy .
Branches .
386
386
386
386
386
387
387
390
Subclavian Arteries.
First Part of Right Subclavian Artery
First Part of Left Subclavian Alter
Second Part of Subclavian Artery
Third Part of Subclavian Artery
Peculiarities
Surgical Anatomy .
Branches .
Vertebral Artery
Basilar Artery .
Circle of Willis .
391
392
393
393
393
394
395
396
397
397
Abdominal Aorta.
Relations
Surgical Anatomy .
Branches
Cceliac Axis, Gastric Artery
Hepatic Artery
Splenic Artery .
Superior Mesenteric Artery
Inferior Mesenteric Artery
Supra-renal Arteries
Renal Arteries .
Spermatic Arteries
Phrenic Arteries
Lumbar Arteries
Middle Sacral Artery
Common Iliac Arteries
Course and Relations
Peculiarities, Surgical Anatomy
Internal Iliac Artery.
Course and Relations
Peculiarities, Surgical Anatomy
Branches
Vesical Arteries
Hemorrhoidal Arteries
Uterine and Vaginal Arteries
Obturator Artery
PAOK
398
398
398
399
400
400
401
402
403
403
404
404
405
407
407
408
409
410
410
411
412
413
414
414
414
415
416
417
417
417
419
420
420
421
422
423
423
425
426
426
427
427
427
428
429
429
430
431
4:52
432
4:12
4:2
4i.2
CONTENTS.
xv
Internal Pudic Artery
Sciatic Artery
Gluteal, Ilio-lumbar, and Lateral
Sacral Arteries .
External Iliac Artery.
Course and Relations .
Surgical Anatomy
Branches
Epigastric Artery .
Circumflex Iliac Artery .
Femoral Artery.
Course and Relations .
Scarpa's Triangle
Peculiarities
Surgical Anatomy
Branches
Profunda Artery
Popliteal Artery.
Popliteal Space
Course and Relations .
Peculiarities, Surgical Anatomy
Branches
PAOE
433
435
436
437
437
437
437
438
438
438
440
440
441
442
443
444
445
445
Anterior Tibial Artery.
Course and Relations
Peculiarities, Surgical Anatomy
Branches
Dorsalis Pedis Artery.
Course and Relations
Peculiarities, Surgical Anatomy
Branches
Posterior Tibial Artery.
Course and Relations
Peculiarities, Surgical Anatomy
Branches
Peroneal Artery.
Course and Relations
Peculiarities ....
Plantar Arteries.
Internal Plantar
External Plantar
Pulmonary Artery.
Right and Left Pulmonary
PAOB
446
447
448
449
449
449
450
450
451
451
452
452
452
454
The Veins.
General Anatomy.
Subdivision into Pulmonary, Systemic,
and Portal 455
Anastomoses of Yeins .... 455
Superficial Veins, Deep Yeins or Venae
Comites 455
Sinuses, their Structure .... 455
Structure of Veins 456
Valves of Veins 457
Vessels and Nerves of Veins . . . 457
Veins of the Head and Neck.
Facial Vein 458
Temporal Vein 459
Internal Maxillary Vein .... 459
Temporo-maxillary Vein .... 459
Posterior Auricular Vein, Occipital Vein 459
Veins of the Neck.
External Jugular Vein .... 460
Posterior External Jugular Vein . . 460
Anterior Jugular Vein .... 460
Internal Jugular Vein .... 460
Lingual, Pharyngeal, and Thyroid Veins 461
Vertebral Veins 461
Veins of the Diploe 461
Cerebral Veins.
Superficial Cerebral Veins . . . 462
Deep Cerebral Veins .... 463
Cerebellar Veins . . . . . 463
Sinuses of the Dura Mater.
Superior Longitudinal Sinus . . . 463
Inferior Longitudinal, Straight, Lateral,
and Occipital Sinuses .... 464
Cavernous Sinuses 465
Circular Sinus 465
Inferior Petrosal, and Transverse Sinuses 466
Superior Petrosal Sinus .... 466
Veins of the Upper Extremitt.
Superficial Veins
Deep Veins
Axillary Vein .
Subclavian Vein
Innominate Veins
Peculiarities of .
Internal Mammary Vein .
Inferior Thyroid Veins
Superior Intercostal Veins
Superior Vena Cava
Azygos Veins .
Spinal Veins .
Veins of the Lower Extremity
Internal Saphenous Vein .
External Saphenous Vein
Popliteal Vein .
Femoral Vein .
External Iliac Vein
Internal Iliac Vein
Common Iliac Vein
Inferior Vena Cava
Peculiarities
Lumbar and Spermatic Veins .
Ovarian, Renal, Supra-renal Veins
Phrenic Veins ....
Hepatic Veins ....
Portal System of Veins.
Inferior and Superior Mesenteric Veins
Splenic and Gastric Veins
Portal Vein
Cardiac Veins.
Coronary Sinus ....
Pulmonary Veins.
Distribution of ....
466
466
468
468
468
469
469
469
470
470
470
471
473
473
474
474
474
474
475
475
476
476
476
476
477
477
477
477
479
479
CONTENTS.
The Lymphatics.
General Anatomy.
PAGE
Structure of, 481
Subdivision into Deep and Superficial . 481
Coats of Lymphatics .... 481
Valves of Lymphatics .... 482
Lymphatic or Conglobate Glands . . 482
Structure of Lymphatic Glands . . 482
Thoracic Duct 483
Right Lymphatic Duct .... 484
Lymphatics of Head, Face, and Neck.
Superficial Lymphatic Glands of Head . 484
Lymphatics of Head . . 484
of the Face . 484
Deep Lymphatics of the Face . . 484
of the Cranium . . 485
Lymphatic Glands of the Neck . . 485
Superficial Cervical Glands . . . 486
Deep Cervical Glands .... 486
Superficial and Deep Cervical Lym-
phatics 486
Lymphatics of the Upper Extremity.
Superficial Lymphatic Glands .
Deep Lymphatic Glands ....
Axillary Glands
Superficial Lymphatics of Upper Ex-
tremity .......
Deep Lymphatics of Upper Extremity .
Lymphatics of the Lower Extremity.
Superficial Inguinal Glands
Deep Lymphatic Glands .
Anterior Tibial Gland
Deep Popliteal Glands
Deep Inguinal Glands
Gluteal and Ischiatic Glands .
Superficial Lymphatics of Lower Ex-
tremity ....
Internal Group .
External Group
Deep Lymphatics of Lower Extremity .
Lymphatics of Pelvis and Abdomen.
Deep Lymphatic Glands of Pelvis .
External Iliac Glands
Internal Iliac Glands
487
487
487
488
488
488
488
489
489
489
489
489
489
489
490
490
490
Sacral Glands
PAGE
490
Lumbar Glands ....
490
Lymphatics of Pelvis and Abdomen
490
Superficial Lymphatics of Wall of Ab-
domen
490
of Gluteal Region
490
of Scrotum and Perineum .
490
of Penis ....
490
of Labia, Nymphse, and
Clitoris
491
Deep Lymphatics of Pelvis and Ab-
domen
491
Lymphatics of Bladder ....
492
of Rectum ....
492
of Uterus ....
492
of Testicle ....
492
of Kidney ....
492
of Liver ....
492
Lymphatic Glands of Stomach
492
Lymphatics of Stomach ....
492
Lymphatic Glands of Spleen .
493
Lymphatics of Spleen ....
493
Lymphatic System of the Intestines.
Lymphatic Glands of Small Intestine
(Mesenteric Glands) ....
493
Lymphatic Glands of Large Intestine
493
Lymphatics of Small Intestine (Lacteals)
493
of Large Intestine
493
Lymphatics of Thorax.
Deep Lymphatic Glands of Thorax
493
Intercostal Glands ....
493
Internal Mammary Glands
493
Anterior Mediastinal Glands .
493
Posterior Mediastinal Glands .
493
Superficial Lymphatics on Front of
Thorax . . .
494
Deep Lymphatics of Thorax .
494
Intercostal Lymphatics ....
494
Internal Mammary Lymphatics
494
Lymphatics of Diaphragm
494
Bronchial Glands
494
Lymphatics of Lung ....
494
Cardiac Lymphatics ....
494
Thymic Lymphatics ....
494
Thyroid Lymphatics ....
494
Lymphatics of (Esophagus
494
Nervous System.
General Anatomy.
Subdivision into Cerebro-spinal Axis,
Ganglia, and Nerves ....
Constituent Elements of Nervous System
Fibrous Nervous Substance . ...
Vesicular Nervous Substance .
Chemical Composition ....
Microscopic Structure of Tubular Fibres
of Gelatinous Fibres
of Vesicular Nervous Substance
Where found.
Ganglia.
Structure
495
495
495
495
495
496
496
496
497
Nerves.
Subdivision into Cerebro-spinal and Sym-
pathetic . . ... 497
General Anatomy of the Nerves . . 498
TJie Spinal Cord and its Membranes.
Dissection 500
Membranes of the Cord .... 500
Dura Mater 500
Arachnoid 501
Pia Mater 502
Lisramcntum Denticulatum . . 502
SpinafCord . .... 502
CONTENTS.
xvn
PAflE
Fissures of Cord .... 503
Columns of Cord .... 503
Structure of Cord .... 504
Mode of Arrangement of Gray and
White Matter . . . .504
"White Matter of Cord. Structure . 504
Gray Substance of Cord. Struc-
ture 505
The Central Canal . . . .506
The Brain and its Membranes.
Membranes of the Brain .... 507
Dura Mater.
Structure ....
. 507
Arteries, Veins, Nerves .
. 507
Glanduhe Pacchioni
. 507
Processes of the Dura Mater .
. 508
Falx Cerebri .
. 508
Tentorium Cerebelli
. 508
Falx Cerebelli
-. 508
Arachnoid Membrant
Subarachnoid Space
. *509
Cerebro-spinal Fluid
. 509
Pia Mater.
The Brain.
Subdivision into Cerebrum, Cerebellum,
Pons Varolii, Medulla Oblongata
510
Weight of Brain ....
510
Medulla Oblongata.
Anterior Pyramids ....
511
Lateral Tract, and Olivary Body
. 511
Restiform Bodies ....
511
Posterior Pyramids ....
511
Posterior Surface of Medulla Oblongata
512
Structure of Medulla Oblongata
512
of Anterior Pyramid
512
of Lateral Tract.
512
of Olivary Body
512
of Restiform Body .
513
Septum of Medulla Oblongata .
513
Gray Matter of Medulla Oblongata .
513
Pons Varolii.
Structure
. 514
Transverse Fibres ....
514
Longitudinal Fibres ....
514
Septum
515
Cerebrum.
Upper Surface of Cerebrum .
515
Convolutions and Sulci .
515
Base of the Brain .....
517
General Arrangement of the Parts com-
posing the Cerebrum .
520
Interior of the Cerebrum .
520
Corpus Callosum
521
Lateral Ventricles
522
Boundaries of, and Parts forming the
Lateral Ventricles
523
Septum Lucidum
525
Fornix
525
Velum Interpositum .
526
Thalami Optici ....
526
Third Ventricle
2
527
Anterior, Middle, and Posterior Commis-
sures
Gray Matter of Third Ventricle
Pineal Gland .
Corpora Quatlrigemina
Valve of Vieussens .
Corpora Geniculata .
Structure of Cerebrum
1. Diverging or Peduncular Fibres
2. Transverse Commissural Fibres
3. Longitudinal Commissural Fibres
Cerebellum.
Its Position, Size, Weight, etc.
Cerebellum, Upper Surface
Under Surface
Lobes of the Cerebellum .
Fourth Ventricle
Boundaries of Ventricle .
Lining Membrane. Choroid Plexus
Gray Matter of Cerebellum
Structure of the Cerebellum
Its Lamina;
Corpus Dentatum
Peduncles of Cerebellum .
Cranial Nerves.
Subdivision into Groups .
Nerves of Special Sense .
of Common Sensation
of Motion
Mixed Nerves .
Olfactory Nerve
Optic Nerve .
Tracts .
Commissure .
Auditory Nerve
Third Nerve
Fourth Nerve .
Sixth Nerve
Relations of the Orbital Nerves
in the Cavernous Sinus
in the Sphenoidal Fissure .
in the Orbit
Facial Nerve ....
Branches of
Ninth or Hypoglossal Nerve .
Fifth Nerve ....
Casserian Ganglion .
Ophthalmic Nerve .
Lachrymal, Frontal, and Nasal Branches
Superior Maxillary Nerve
Inferior Maxillary Nerve .
Auriculotemporal, Gustatory, and In-
ferior Dental Branches . . . 550,
Ophthalmic Ganglion
Sphenopalatine Ganglion
Otic Ganglion .
Submaxillary Ganglion
Eighth Pair
Glosso-pharyngeal
Pneumogastric .
Spinal Accessory
Spinal Nerves.
Roots of the Spinal Nerves
Origin of Anterior Roots .
of Posterior Roots
Ganglia of the Spinal Nerves .
561
56L
561
562
XY1U
CONTENTS.
Anterior Branches of the Spinal Nerves . 562
Posterior Branches of the Spinal Nerves 562
Cervical Nerves.
Roots of the Cervical Nerves . . . 562
Anterior Branches of the Cervical Nerves 563
Cervical Plexus.
Superficial Branches #>f the Cervical
Plexus 564
Deep Branches of the Cervical Plexus . 565
Posterior Branches of the Cervical Nerves 565
Brachial Plexus.
Branches above the Clavicle.
Posterior Thoracic, Supra-scapular 567, 568
Branches below the Clavicle.
Anterior Thoracic, and Subscapular
Nerves 568, 569
Circumflex, and Musculo - cutaneous
Nerves 569
Internal, and Lesser Internal Cutaneous
Nerves 570
Median Nerve 571
Ulnar Nerve 573
Musculo-spiral Nerve .... 574
Radial Nerve 575
Posterior Interosseous Nerve . . 575
Dorsal Nerves.
Roots of the Dorsal Nerves . . . 576
Intercostal Nerves 576
Upper Intercostal Nerves . . . 576
Intercosto-humeral Nerves . . . 577
Lower Intercostal Nerves . . . 577
Peculiar Dorsal Nerves .... 577
First Dorsal Nerve .... 577
Last Dorsal Nerve .... 577
Lumbar Nerves.
Roots of Lumbar Nerves .... 578
Posterior Branches of Lumbar Nerves . 578
Anterior Branches of Lumbar Nerves . 578
Lumbar Plexus.
Branches of Lumbar Plexus . . . 578
Uio-hypogastric Nerve .... 578
Ilio-inguinal, and Genito-crural Nerves . 580
External Cutaneous, and Obturator Nerves 580
Accessory Obturator Nerve . . . 582
Anterior Crural Nerve .... 582
Branches of 582
Middle Cutaneous 583
Internal Cutaneous, Long Saphenous . 583
Muscular and Articular Branches . 584
Sacral and Coccygeal Nerves.
Roots of origin of 584
Posterior Sacral Nerves .... 584
Anterior Sacral Nerves .
Posterior Branch of Coccygeal Nerve
Anterior Branch of Coccygeal Nerve
Sacral Plexus.
Superior Gluteal Nerve .
Pudic and Small Sciatic Nerves
Great Sciatic Nerve ....
Internal Popliteal Nerve .
Posterior Tibial Nerve
Plantar Nerves ....
External Popliteal or Peroneal Nerve
Anterior Tibial Nerve
Musculo-cutaneous Nerve
Sympathetic Nerve.
Subdivision of
Branches of the Ganglia,
scription of .
General De-
PAOB
585
585
585
586
586
588
588
589
589
590
590
591
592
592
Cephalic Portion of Sympathetic
Ganglia of
Cervical Portion of the Sympathetic.
Superior Cervical Ganglion
Middle Cervical Ganglion
Inferior Cervical Ganglion
Carotid and Cavernous Plexuses
Cardiac Nerves.
Superior, Middle, and Inferior Cardiac
Nerves
Deep Cardie Plexus ....
Superficial Cardiac Plexus
Anterior and Posterior Coronary Plexus
Thoracic Part of the Sympathetic.
Great Splanchnic Nerve . . .
Lesser Splanchnic Nerve
Smallest Splanchnic Nerve
Epigastric or Solar Plexus
Semilunar Ganglia ....
Phrenic, Supra-renal, and Renal Plexuses
Spermatic, Cceliac, and Gastric Plexuses
Hepatic, Splenic, and Superior Mesen-
teric Plexuses . . . .
Aortic, and Inferior Mesenteric Plexuses
594
594
595
595
595
596
596
597
597
597
598
598
598
598
598
599
599
599
Lumbar Portion of Sympathetic. 600
Branches of
Pelvic Portion of Sympathetic
Hypogastric Plexus
Inferior Hypogastric or Pelvic Plexus
Inferior Hemorrhoidal Plexus
Vesical Plexus
Prostatic Plexus ....
Vaginal Plexus .....
Uterine Nerves ....
600
600
600
600
601
601
601
601
601
CONTENTS.
xix
Organs of Sense.
Skin
Derma or true Skin .
Corium
Papillary Layer
Epidermis or Cuticle
Vessels and Nerves of the Skin
Appendages of the Skin.
Nails
Hairs
Sebaceous
md Sudoriferous Glands
Tongue.
Papillae of, and their Structure
Follicles, and Mucous Glands of
Fibrous Septum of .
Muscular Fibres of .
Arteries and Nerves of .
Nose.
Cartilages of .
Muscles of ... .
Skin, Mucous Membrane .
Arteries, Veins, and Nerves .
Nasal Fossa?.
Mucous Membrane of ...
Peculiarities of, in Superior, Middle, and
Inferior Meatuses
Arteries, Veins, and Nerves of Nasal
Fossae
Eye.
Situation, Form of .
Tunics of
Sclerotic and its Structure
Cornea and its Structure .
Choroid and its Structure
Ciliary Processes ....
Iris
Membrana Pupillaris, Ciliary Ligament
Ciliary Muscle
Retina
Structure of Retina
Jacob's Membrane
Granular Layer
Nervous Layer ....
Radiating Fibres of the Retina
Arteria Centralis Retina;
Structure of Retina, at Yellow Spot
Humors of the Eye.
Aqueous Humor
Anterior Chamber .
Posterior Chamber .
Vitreous Body ....
Crystalline Lens and its Capsule
Changes produced in the Lens by Age
615
PAGE
602
603
603
604
605
605
606
607
609
610
610
610
611
612
612
612
613
613
613
614
614
615
616
616
617
618
619
620
620
620
621
621
621
621
622
622
622
622
622
622
623
623
624
Suspensory Ligament of Lens . . 624
Canal of Petit 684
Vessels of the Globe of the Eye . . 024
Nerves of Eyeball .625
Appendages of the Eye
Eyebrows . . . . . . &25
Eyelids 625
Structure of the Eyelids . . . .625
Tarsal Cartilages 625
Meibomian Glands 626
Eyelashes . .... 626
Conjunctiva 626
Caruncula Lacrymalis .... 627
Lachrymal Apparatus.
Lachrymal Gland 628
Canals 628
Sac 628
Nasal Duct 628
Ear.
Pinna or Auricle 628
Structure of Auricle .... 628
Ligaments of the Pinna .... 629
Muscles of the Pinna .... 630
Arteries, Veins, and Nerves of the Pinna 631
Auditory Canal 631
Middle Ear or Tympanum.
Openings in Cavity of ... 632
Walls of 632, 633, 634
Eustachian Tube 634
Membrana Tympani .... 634
Structure of 634
Ossicles of the Tympanum . . . 634
Ligaments of the Ossicula . . . 635
Muscles of the Tympanum . . . 636
Mucous Membrane of Tympanum . . 636
Arteries, Veins, and Nerves of Tym-
panum 636, 637
Internal Ear or Labyrinth.
Vestibule
Semicircular Canals
Superior Semicircular Canal
Posterior Semicircular Canal .
External Semicircular Canal
Cochlea
Central Axis or Modiolus
Spiral Canal ....
Lamina Spiralis ....
Scala Tympani, Scala Vestibuli
Membranous Labyrinth .
Utricle and Saccule
Membranous Semicircular Canals
Structure of the (Membranous) Labyrinth
Vessels of the Labyrinth
Auditory Nerve, Vestibular Nerve, Coch
lear Nerve
637
638
638
638
638
639
639
639
640
640
640
641
641
641
641
642
CONTENTS.
VISCERA.
Organs of Digestion and their Appendages.
Alimentary Canal
Its Subdivisions
The Mouth
The Lips .
The Cheeks
The Gums
Teeth.
General Characters of
Permanent Teeth ....
Incisors, Canine, Bicuspid, Molars .
Temporary or Milk Teeth
Structure of the Teeth
Ivory or Dentine, Chemical Composition
Enamel, Cortical Substance
Development of the Teeth
of the Permanent Teeth .
Growth of the Teeth
Eruption of the Teeth
Palate.
Hard Palate
Soft Palate
Uvula, Pillars of the Soft Palate
Mucous Membrane, Aponeurosis, and
Muscles of Soft Palate
Tonsils.
Arteries, Veins, and Nerves of Tonsils .
Salivary Glands.
Parotid Gland.
Steno's Duct . . .
Vessels and Nerves of Parotid Gland
Submaxillary Gland.
Wharton's Duct *
Vessels and Nerves of Submaxillary
Gland
Sublingual Gland.
Vessels and Nerves of ...
Structure of Salivary Glands .
Structure of
Pharynx.
(Esophagus.
PAGE
643
643
643
643
644
644
645
646
646
647
648
648
649
649
649
651
651
652
652
652
653
653
654
655
655
655
655
655
656
Kelations, Surgical Anatomy, and Struc-
ture of
Abdomen.
Boundaries
Apertures of .
Regions .
657
658
659
659
Peritoneum.
Reflections traced .
Foramen of Winslow
660
661
Lesser Omentum ....
PAGE
. 662
Great Omentum
. 662
Gastro-splenic Omentum .
. 662
Mesentery
. 662
Mesocaecum, Mesocolon .
. 663
Stomach.
663
Splenic end, Pyloric end .
. 663
Cardiac and Pyloric Orifices .
. 663
Greater and Lesser Curvatures
. 683
664
Ligaments of .
. 664
Alterations in Position
. 664
Pylorus
. 665
Structure of Stomach
. 665
Serous and Muscular Coats
. 666
Mucous Membrane .
. 666
Gastric Follicles
. 666
Vessels and Nerves of Stomach
. 667
Small Intestines.
Duodenum ....
. 667
Ascending portion
. 667
Descending portion .
. 667
Transverse portion .
. 667
Vessels and Nerves of Duodenum
. 668
. 668
, 668
Structure of Small Intestines .
. 668
Serous, Muscular, and Cellular Coats . 668
Mucous Membrane .
. 668
Epithelium and Valvuke Conniventes . 668
Villi — their Structure
. 669
Simple Follicles, Duodenal Glands
. 669
Solitary Glands
. 969
Aggregate Glands .
. 670
Large Intestine.
. 670
Appendix Vermiformis Caeci
. 671
Ileo-caecal Valve
. 671
, 672
Ascending
. 672
Transverse
. 672
Descending
. 672
Sigmoid Flexure
. 672
672
Upper portion .
. 673
Middle portion .
. 673
Lower portion .
. 673
Structure of Large Intestine .
. 673
Serous and Muscular Coats
. 673
Cellular and Mucous Coats
. 674
Epithelium, Simple Follicles .
. 674
Solitary Glands
. 675
Liver.
Size, Weight, Position of
. 675
Its Surfaces and Borders
. 675
Changes of Position
. 675
CONTENTS.
xxi
PAGE
Ligaments of the Liver .... 675
Longitudinal, Lateral. Coronary . 676
Round Ligament .... 676
Fissures of the Liver .... 676
Longitudinal 67G
Fissure of Ductus Yenosus, Portal Fis-
sure 677
Fissures for Gall-bladder and Vena Cava 677
Lobes of the Liver 677
Eight, Left .... 677, G78
Lobus Quadratus, L. Spigelii, L. Cauda-
tus 678
Vessels of Liver 678
Lymphatics, Nerves .... 678
Structure of Liver 678
Serous Coat 678
Fibrous Coat 679
Lobules 679
Hepatic Cells 679
Biliary Ducts, Portal Vein . . .680
Hepatic Artery, Hepatic Veins . . 680
Gall-bladder.
Structure 681
Biliary Ducts 681
Hepatic Ducts 681
Cystic, and Common Choledoch
Ducts 682
Structure of Biliary Ducts . . 682
Pancreas.
Dissection 682
Relations 683
Duct 683
Structure, Vessels, and Nerves . 684
Spleen.
Relations . . . . . . .684
Size and Weight . . . . .684
Structure of Serous and Fibrous Coats . 685
Proper Substance 685
Malpighian Corpuscles .... 686
Splenic Artery and its distribution . . 687
Capillaries of Spleen .... 688
Veins of Spleen 688
Lymphatics and Nerves . . . 689
Thorax.
PAllE
Boundaries of 689
Superior Opening, Base .... 689
Parts passing through Upper Opening . 689
Pericardium.
Structure 689
Fibrous Layer, Serous Layer . . . 680
Heart.
Position, Size 691
Subdivision into Four Cavities . . 691
Circulation of Blood in Adult . . . 691
Auriculo-ventricular, and Ventricular
Grooves 691
Right Auricle.
Openings 693
Valves 693
Relics of Foetal Structure . . .693
Musculi Pectinati 693
Right Ventricle.
Openings 694
Tricuspid Valve 694
Semilunar Valves 695
Chorda? Tendineae and Columnae Carnea; . 695
Left Auricle.
Sinus and Appendix . . . . 695
Openings, Musculi Pectinati . . . 696
Left Ventricle.
Openings 697
Mitral and Semilunar Valves . . . 697
Endocardium 697
Structure of Heart.
Fibrous Rings 697
Muscular Structure 698
of Auricles .... 698
of Ventricles . . . .698
Vessels and Nerves of Heart . . . 699
Peculiarities in Vascular System of Foetus 699
Foramen Ovale, Eustachian Valve . . 699
Ductus Arteriosus 699
Umbilical or Hypogastric Arteries . .699
Fcetal Circulation 700
Changes in Vascular System at Birth . 702
Organs of Yoice and Eespiration.
Tlie Larynx.
Cartilages of the Larynx
Thyroid Cartilage
Cricoid and Arytenoid Cartilages
Cartilages of Santorini andWrisberg
Epiglottis. Its Structure
Ligaments of the Larynx
Ligaments connecting the Thyroid Carti
lage with the Os Hyoides
Ligaments connecting the Thyroid Carti
lage with the Cricoid ...
Ligaments connecting the Arytenoid Car-
tilages to the Cricoid .
Ligaments of the Epiglottis .
Upper Aperture of the Larynx
Cavity of the Larynx
Glottis
False Vocal Cords ....
703
703
704
705
705
705
705
706
706
706
706
707
707
707
True Vocal Cords ....
708
Ventricle of Larynx, Sacculus Laryngis
708
Muscles of Larynx .....
708
Crico-thyroid ....
708
Crico-arytaenoideus posticus
708
lateralis
709
Thyro-arytaenoideus .
709
Muscles of the Epiglottis .
709
Thyro-epiglottideus .
710
Arytaeno-epiglottideus, superior
710
inferior
710
Actions of Muscles of Larynx
710
Mucous Membrane of Larynx .
710
Glands, Vessels and Nerves of
711
Trachea.
Relations
712
Bronchi
712
xxu
CONTENTS.
PAOK
Struciure of Trachea .... 712
Surgical Anatomy of Laryngotracheal
Eegion . 713
The Pleura.
Eeflections 715
Vessels and Nerves . . . .716
Mediastinum.
Anterior Mediastinum .... 716
Middle Mediastinum .... 716
Posterior Mediastinum . . . .716
The Lungs.
Surfaces, Lobes 717
Eoot of Lung 719
Weight, Color, and Properties of Sub-
stance of Lung 719
Structure of Lung 719
Serous Coat, and Subserous AreolarTissue 719
PABB
Parenchyma and Lobules of Lung . . 719
Bronchi, Arrangement of in Substance of
Lung 719
Structure of Smaller Bronchial Tubes . 720
The Air-cells 720
Pulmonary Artery 720
Pulmonary Capillaries and Veins . . 720
Bronchial Arteries and Veins . . . 720
Lymphatics and Nerves of Lung . . 721
Thyroid Gland.
Structure 721
Vessels and Nerves .... 721
Chemical Composition .... 722
Tliymus Gland.
Structure 722
Vessels and Nerves .... 723
Chemical Composition .... 723
The Urinary Organs.
Kidneys.
Eelations
Dimensions, Weight
Cortical Substance .
Medullary Substance
Minute Structure
Malpighian Bodies .
Ureter, Pelvis, Infundibula
Eenal Artery, Eenal Veins
Lymphatics and Nerves .
Ureters.
Situation, Course, Eelations
Structure
Supra-renal Capsules.
Eelations
724
724
724
725
725
726
726
726
727
727
727
727
Structure
Vessels and Nerves
Pelvis.
Boundaries and Contents
Bladder.
Shape, Position, Eelations
Subdivisions
Ligaments
Structure .
Interior of Bladder
Vessels and Nerves
Male Urethra.
Membranous Portion
Spongy Portion
Structure .
728
728
728
729
730
730
731
731
732
733
733
733
Male Generative Organs.
Prostate Gland ....
735
Structure
735
Vessels and Nerves .
736
Cowper's Glands . .
736
Prostatic Secretion ....
736
Penis.
Eoot
736
Glans Penis
736
Body .......
736
Corpora Cavernosa ....
737
Structure
737
Corpus Spongiosum
737
The Bulb
737
Structure of Corpus Spongiosum
738
Erectile Tissue ....
738
Arteries of the Penis
738
Lymphatics of the Penis .
738
Nerves of the Penis
738
• The Testes.
Form and Situation
739
Size and Weight ....
739
Scrotum
739
Other Coverings of the Testis .
739
Proper Coverings of the Testis
739
Tunica Vaginalis
740
Tunica Albuginea
740
Mediastinum Testis .
740
Tunica Vasculosa
740
Structure of the Testis
741
Lobules of the Testis
741
Number, Size, Shape, Position
741
Structure of the Lobuli Testis
741
Tubuli Seminiferi ....
. 741
Arrangement in Lobuli .
741
in Mediastinum Testis
741
in Epididymis
741
Vasculum Aberrans
741
Vas Deferens, Course, Eelations
742
Structure
742
Vessels and Nerves of the Coverings o
F
the Testis
742
Spermatic Cord.
Its Composition ....
742
Eelations of in Inguinal Canal
742
Arteries of the Cord
742
Veins of the Cord ....
743
Lymphatics and Nerves of the Cord
743
CONTENTS.
xxin
Vesicvlce Seminales.
Form and Size
Relations .
Structure .
PAOE
743
744
744
Ejaculatory Ducts .
Structure of
The Semen
Descent of the Testes
Gubernaculum Testis
PAOK
744
744
744
744
745
Female Organs of Generation.
Mons Veneris, Labia Majora .
Labia Minora, Clitoris, Meatus Urinarius
Hymen, Glands of Bartholine .
Bladder . . . . •
Urethra
Rectum .......
Vagina.
Relations
Structure
Uterus.
Situation, Form, Dimensions
Fundus, Body and Cervix
Ligaments
Cavity of the Uterus
Structure ....
Vessels and Nerves .
Its Form, Size, and Situation
in the Foetus
at Puberty
746
747
747
748
748
749
749
749
750
750
750
750
751
751
752
752
752
during and after Menstruation
752
after Parturition
752
in Old Age
752
Appendages oftlie Uterus.
Fallopian Tubes ....
752
Structure .
752
Ovaries .
752
Structure .
753
Graafian Vesicles
753
Ovum
754
Discharge of the Ovum
754
Corpus Luteum
754
Ligament of the Ovary
755
Round Ligaments .
755
Vessels and Nerves of Appendages
755
Mammary Glands.
Structure of Mamma
. 756
Vessels and Nerves
. 757
Surgical Anatomy of Inguinal Hernia.
Dissection
758
Inguinal Hernia.
Superficial Fascia
Superficial Vessels and Nerves
758
758
Varieties of
. 764
Deep Layer of Superficial Fascia
758
Oblique Inguinal Hernia.
Aponeurosis of External Oblique
759
External Abdominal Ring
760
Course and Coverings of . ...
764
Pillars of the Ring .
760
Seat of Stricture ....
764
Intercolumnar Fibres
760
Scrotal Hernia ....
765
Fascia
760
Bubonocele
765
Poupart's Ligament
760
Congenital Hernia ....
765
Gimbernat's Ligament
761
Infantile Hernia
765
Internal Oblique Muscle
761
Triangular Ligament
Cremaster
761
761
Direct Inguinal Hernia.
Trans versalis Muscle
762
Course and Coverings of the Hernia
765
Spermatic Canal
Fascia Transversalis
762
Seat of Stricture ....
765
#
763
Incomplete Direct Hernia
766
Internal Abdominal Ring
763
Comparative Frequency of Oblique ant
Subserous Areolar Tissue
763
Direct Hernia ....
76G
Epigastric Artery .
764
Diagnosis of Oblique and Direct Hernia
766
Peritoneum
764
Surgical Anatomy of Femoral Hernia.
Dissection
766
Superficial Fascia ....
766
Cutaneous Vessels ....
766
Internal Saphenous Vein ' .
Superficial Inguinal Glands
767
767
Cutaneous Nerves ....
767
Deep Layer of Superficial Fascia .
768
Cribriform Fascia ....
768
Fascia Lata
768
Iliac Portion ....
768
Pubic Portion ....
769
Saphenous Opening ....
769
Crural Arch
Gimbernat's Ligament
Crural Sheath .
Deep Crural Arch .
Crural Canal .
Femoral or Crural Ring
Position of Parts around the Ring
Septum Crurale
Descent of Femoral Hernia
Coverings of Femoral Hernia .
Varieties of Femoral Hernia .
Seat of Stricture
769,
769
770
770
771
771
771
771
772
773
773
773
774
XXIV
CONTENTS.
Surgical Anatomy of Perineum and Ischio-rectal Region.
Ischio-rectal Region.
Dissection
Boundaries of .
Superficial Fascia
External Sphincter
Internal Sphincter
Ischio-rectal Fossa
Position of Parts contained in
Perineum.
Boundaries, and Extent .
Superficial Layer of Superficial Fascia
Deep Layer of Superficial Fascia .
Course taken by the Urine in Rupture
of the Urethra ....
Muscles of the Perineum (Male)
Accelerator Urina? .
Erector Penis
Transversus Perinei
Superficial Perineal Vessels and Nerves
Transversus Periaei Artery
Muscles of the Perineum (Female)
Sphincter Vaginae ....
Erector Clitoridis ....
PAGE
775
775
775
776
77G
776
776
777
777
777
778
778
778
77'.)
779
780
780
780
780
780
Transversus Perinei
Compressor Urethra;
Levator Ani
Deep Perineal Fascia
Anterior Layer
Posterior Layer
Parts between the two Layers
Compressor Urethra;
Cowper's Glands
Pudic Vessels and Nerves
Artery of the Bulb .
Levator Ani
Relations, Actions .
Coccygeus, Relations, Actions
Position of Viscera at Outlet of Pelvis
Parts concerned in the Operation of
Lithotomy
Parts divided in the Operation
Parts to be avoided in the Operation
Abnormal Course of Arteries in the
Perineum
Pelvic Fascia .
Obturator Fascia
Recto-vesical Fascia
780
780
780
781
781
781
781
781
781
781'
781
781
782
782
782
783
784
784
785
785
786
786
Surgical
Anatomy of Muscles of the Extremities
320
—354
a
" Talipes ....
*
. 348
" Arteries
" Triangles of the Neck .
364—450
. 382
u
" Axilla ....
401
u
" Bend of Elbow
407
u
" Scarpa's Triangle
.
438
u
11
" Popliteal Space
" (Esophagus
•
443
657
«
" Laryngotracheal Region
713
• (
" Inguinal Hernia
7G2
u
((
" Femoral Hernia
•" Perineum
" Prostate Gland
•
\
766
775
782
-
" Base of Bladder
,
783
LIST OF ILLUSTRATIONS.
4S* The Illustrations, when copied from any other work, have the author's name affixed ; when no such acknow-
ledgment is made, the drawing is to be considered original. Those marked with * are new in this edition.
FIG
1.
2.
3.
4.
5.
6.
7.
8
14,
15.
16.
17
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
Osteology.
A Cervical Vertebra
Atlas ....
Axis ....
*Seventh Cervical Vertebra
A Dorsal Vertebra
Peculiar Dorsal Vertebrae
A Lumbar Vertebra
to 13. Development of the Vertebrae
Sacrum, anterior surface
* Vertical Section of the Sacrum
Sacrum, posterior surface
to 19. Development of Sacrum .
Coccyx, anterior and posterior surfaces
Lateral View of Spine .
Occipital Bone, outer surface
Occipital Bone, inner surface
Occipital Bone, development of
Parietal Bone, external surface
Parietal Bone, internal surface
Frontal Bone, outer surface
Frontal Bone, inner surface
*Frontal Bone at Birth .
Temporal Bone, outer surface
Temporal Bone, inner surface
Temporal Bone, petrous portion
Temporal Bone, development of
Sphenoid Bone, superior surface
Sphenoid Bone, anterior surface
Sphenoid Bone, posterior surface
Plan of the Development of Sphenoid
Ethmoid Bone, outer surface
Perpendicular Plate of Ethmoid
*Ethmoid Bone, inner surface of right lateral mass
*Skull at Birth, showing the anterior and posterior Fontanelles
*Lateral Fontanelles
Nasal Bone, outer surface
Nasal Bone, inner surface
Superior Maxillary Bone, outer surface
Superior Maxillary Bone, inner surface
Development of Superior Maxillary Bone
Lachrymal Bone, outer surface .
Malar Bone, outer surface
Malar Bone, inner surface
Palate Bone, internal view
Quain
Quain
Quain
Quain
Quain
( xxv )
XXVI
LIST OF ILLUSTRATIONS.
FIG.
52. Palate Bone, posterior view
53. Inferior Turbinated Bone, inner surface
54. Inferior Turbinated Bone, outer surface
55. Vomer .....
56. Inferior Maxillary Bone, outer surface .
57. Inferior Maxillary Bone, inner surface .
58. *Side-view of the Lower Jaw, at Birth
59. *Side-view of the Lower Jaw, at Puberty
60. *Side-view of the Lower Jaw, in the Adult
61. *Side-view of the Lower Jaw, in Old Age
62. Base of Skull, inner surface
63. Base of Skull, outer surface
64. *Side-view of the Skull .
65. Anterior Region of Skull
66. Nasal Fossae, roof, floor, and wall
67. Nasal Fossae, inner wall or septum
68. Hyoid Bone, anterior surface
69. Sternum and Costal Cartilages, anterior surface
70. Sternum, posterior surface
71 to 74. Development of Sternum
75. A Rib .
76. Vertebral Extremity of a Rib .
77 to 81. Peculiar Ribs
82. Clavicle, anterior surface
83. Clavicle, inferior surface
84. Scapula, anterior surface or venter
85. Scapula, posterior surface or dorsum
86. Plan of the Development of the Scapula
87. Humerus, anterior view .
88. Humerus, posterior surface
89. Plan of the Development of the Humerus
90. Bones of the Forearm, anterior surface
91. Bones of the Forearm, posterior surface
92. Plan of the Development of the Ulna .
93. Plan of the Development of the Radius
94. Bones of the Hand, dorsal surface
95. Bones of the Hand, palmar surface
96. Plan of the Development of the Hand .
97. Os innominatum, external surface
98. Os Innominatum, internal surface
99. Plan of the Development of the Os Innominatum
100. *Male Pelvis (adult) ....
101. *Female Pelvis (adult) . .
102. *Vertical Section of the Pelvis, with lines indicating the Axes of the
103. Right Femur, anterior surface .
104. Right Femur, posterior surface .
105. *Diagram showing the Structure of the Neck of the Femur
106. Plan of the Development of the Femur
107. Right Patella, anterior surface .
108. Right Patella, posterior surface
109. Tibia and Fibula, anterior surface
110. Tibia and Fibula, posterior surface
111. Plan of the Development of the Tibia
112. Plan of the Development of the Fibula
113. Bones of the Foot, dorsal surface
114. Bones of the Foot, plantar surface
115. Plan of the Development of the Foot
Pelvis
Ward
LIST OF ILLUSTRATIONS.
XXTll
Articulations.
FIO.
116. Vertical Section of Two Vertebra; and their Ligaments, front view
117. Occipito-atloid and Atlo-axoid Ligaments, front view .
118. Occipito-atloid and Atlo-axoid Ligaments, posterior view
119. Articulation between Odontoid Process and Atlas
120. Occipito-axoid and Atlo-axoid Ligaments
121. Temporo-maxillary Articulation, external view
122. Temporo-maxillary Articulation, internal view
123. Temporo-maxillary Articulation, vertical section
124. Costo-vertebral and Costo-transverse Articulations, anterior view
125. Costo-transverse Articulation .....
126. Costo-sternal, Costo-xiphoid, and Intercostal Articulations, anterior
127. Articulations of Pelvis and Hip, anterior view
128. Articulations of Pelvis and Hip, posterior view
129. Vertical Section of the Symphysis Pubis
130. Sterno-clavicular Articulation .....
131. Shoulder-Joint, Scapuloclavicular Articulation, and proper Ligament
132. Elbow-Joint, showing anterior and internal Lateral Ligaments
133. Elbow-Joint, showing posterior and external Lateral Ligaments
134. Ligaments of "Wrist and Hand, anterior view .
135. Ligaments of Wrist and Hand, posterior view .
136. Vertical Section of Wrist, showing the Synovial Membranes
137. Articulations of the Phalanges
138. Hip-Joint, laid open
139. Knee-Joint, anterior view
140. Knee-Joint, posterior view
141. Knee-Joint, showing internal Ligaments
142. Head of Tibia, with semilunar Cartilages, &c, seen from above
143. Ankle-Joint, Tarsal and Tarso-metatarsal Articulations, internal view
144. Ankle-Joint, Tarsal and Tarso-metatarsal Articulations, external view
145. Ligaments of Plantar surface of the Foot .
146. Svnovial Membranes of the Tarsus and Metatarsus
Muscles and Fascise.
147. Plan of Dissection of the Head, Face, and Neck
148. Muscles of the Head, Face, and Neck .
149. Muscles of the right Orbit
150. Relative position and attachment of the Muscles of the left Eyeball
151. Temporal Muscle ....
152. Pterygoid Muscles . . .
153. Muscles of the Neck, and Boundaries of the Triangles
154. Muscles of the Neck, anterior view
155. Muscles of the Tongue, left side
156. Muscles of the Pharynx, external view .
157. Muscles of the Soft Palate
158. The Prevertebral Muscles ....
159. Plan of Dissection of the Muscles of the Back .
160. Muscles of tjie Back — first, second, and part of the third layers
161. Muscles of the back — deep layers
162. Plan of Dissection of Abdomen
163. External Oblique Muscle
164. Internal Oblique Muscle
165. Transversalis, Rectus, and Pyramidalis Muscles
166. Transverse Section of Abdomen in Lumbar Region
167. Diaphragm, under surface
168. Dissection of Upper Extremity .
view
Arnold
Arnold
s of Scapula
Arnold
do.
Arnold
uam
Quain
XXV111
LIST OF ILLUSTRATIONS.
Fia.
169. Muscles of the Chest and Front of the Arm, superficial view
170. Muscles of the Chest and Front of the Arm, with the boundaries of the Axilla
171. Muscles on the Dorsum of the Scapula and the Triceps
172. Front of the Forearm, superficial muscles
173. Front of the Forearm, deep muscles
174. Posterior surface of Forearm, superficial muscles
175. Posterior surface of Forearm, deep muscles
176. *Transverse section through the Wrist, showing Posterior Annular
Canals for the passage of the Extensor Tendons
177. Muscles of the Hand, palmar surface .
178. Dorsal Interossei of Hand
179. Palmar Interossei of Hand
180. Fracture of the Middle of the Clavicle .
181. Fracture of the Surgical Neck of the Humerus
182. Fracture of the Humerus above the Condyles .
183. Fracture of the Olecranon
184. Fracture of shaft of the Radius .
185. Fracture of the lower end of the Radius
186. Plan of Dissection of Lower Extremity, front view
187. Muscles of the Iliac and Anterior Femoral Eegions
188. Muscles of the Internal Femoral Region
189. Plan of Dissection of Lower Extremity, posterior view
190. Muscles of the Hip and Thigh .
191. Muscles of the Front of the Leg
192. Muscles of the back of the Leg, superficial layer
193. Muscles of the back of the Leg, deep layer
194. Muscles of the sole of the Foot, first layer
195. Muscles of the sole of the Foot, second layer .
196. Muscles of the sole of the foot, third layer
197. Dorsal Interossei of Foot
198. Plantar Interossei of Foot
199. Fracture of the neck of the Femur within the Capsular Ligament
200. Fracture of the Femur below the Trochanters .
201. Fracture of the Femur above the Condyles
202. Fracture of the Patella ....
203. Oblique fracture of the shaft of the Tibia
204. Fracture of the Fibula, with displacement of the Tibia
Arteries.
205. Arch of the Aorta and its branches
206. Plan of the branches of the Arch of the Aorta
207. Surgical Anatomy of the. Arteries of the Neck
208. Plan of the branches of the External Carotid .
209. Arteries of the Face and Scalp .
210. The Internal Maxillary Artery, and its branches
211. Plan of the branches of the Internal Maxillary Artery
212. Internal Carotid and Vertebral Arteries
213. Ophthalmic Artery and its branches
214. Arteries of the base of the Brain
215. Plan of the branches of the Right Subclavian Artery
216. Scapular and Circumflex Arteries
217. Axillary Artery, and its branches
218. Surgical Anatomy of the Brachial Artery " .
219. Surgical Anatomy of the Radial and Ulnar Arteries
220. Ulnar and Radial Arteries, deep view .
221. Arteries of the back of the Forearm and Hand
222. Abdominal Aorta and its branches
PAGE
295
he Axilla
297
301
306
• 309
.
311
311
Ligament, and
315
.
317
.
319
. .
320
Hind
321
do.
321
do.
322
do.
322
do.
323
do.
324
327
328
Q
uain
332
335
336
341
343
345
351
352
353
354
354
Hind
355
do.
355
do.
356
do.
356
do.
356
do.
357
362
362
369
369
374
380
380
385
387
389
395
399
401
406
410
413
415
41,9
LIST OF ILLUSTRATIONS.
. XXIX
FIG.
223. C celiac Axis and its branches, the Liver having been raised, and the Lesser Omen-
tum removed ........
224. Cceliac Axis and its branches, the Stomach having been raised, and the Transverse
Mesocolon removed .....
225. Superior Mesenteric Artery and its branches .
226. Inferior Mesenteric Artery and its branches
227. Arteries of the Pelvis .....
228. 229. Variations in Origin and Course of Obturator Artery
230. Arteries of the Gluteal and Posterior Femoral Regions
231. Surgical Anatomy of the Femoral Artery
232. Popliteal, Posterior Tibial, and Peroneal Arteries
233. Surgical Anatomy of the Anterior Tibial and Dorsalis Pedis Arteries
234. Plantar Arteries, superficial view
235. Plantar Arteries, deep view ....
Yeins.
236. Veins of the Head and Neck ........
237. Veins of the Diploe, as displayed by the removal of the outer table of the Skull Breschet
238. Vertical Section of the Skull, showing the Sinuses of the Dura Mater
239. Sinuses at the Base of the Skull .....
240. Superficial Veins of the Upper Extremity ....
241. Vena? Cavae and Azygos Veins, with their Formative Branches
242. Transverse Section of a Dorsal Vertebra, showing the Spinal Veins Breschet
243. Vertical Section of two Dorsal Vertebra?, showing the Spinal Veins
244. Internal or long Saphenous Vein and its Branches
245. External or short Saphenous Vein . . .
246. Portal Vein and its Branches .....
421
422
424
426
429
433
435
439
446
448
453
453
458
462
464
465
466
469
472
472
473
474
478
Lymphatics.
247. Thoracic and Right Lymphatic Ducts ....
248. Superficial Lymphatics and Glands of the Head, Face, and Neck
249. Deep Lymphatics and Glands of the Neck and Thorax
250. Superficial Lymphatics and Glands of the Upper Extremity .
251. Superficial Lymphatics and Glands of the Lower Extremity .
252. Deep Lymphatic Vessels and Glands of the Abdomen and Pelvis
Nervous System.
253. Spinal Cord and its Membranes ....
254. Transverse Section of the Spinal Cord and its Membranes
255. Spinal Cord, side view. Plan of the Fissures and Columns .
256. Transverse Sections of the Cord ... .
257. *Transverse Section of the Gray Substance of the Spinal Cord, i
near the middle of the Dorsal Region . . . j
258. *Transverse Section of the Gray Substance of the Spinal Cord, -i
through the middle of the Lumbar Enlargement . . j
259. *Longitudinal Section of the White and Gray Substance of the i
Spinal Cord, through the middle of the Lumbar Enlargement j
260. Medulla Oblongata and Pons Varolii, anterior surface
261. Posterior Surface of Medulla Oblongata
262. Transverse Section of Medulla Oblongata
263. Columns of the Medulla Oblongata, and their Connection with the l
Cerebrum and Cerebellum .....)
264. Upper Surface of the Brain, the Pia Mater having been removed
265. Base of the Brak ......
266. Section of the Brain, made on a level with the Corpus Callosum
Mascagni
do.
do.
do.
do.
Arnold
Quain
Arnold
do.
do.
Arnold
Altered from
Arnold
483
485
486
487
489
491
501
501
503
504
J. L. Clarke 505
505
506
511
512
512
513
516
518
521
XXX
LIST OF ILLUSTRATIONS.
267. Lateral Ventricles of the Brain ....... 522
268. Fornix, Velum Interpositum, and Middle or Descending Cornu of the Lateral Ventricle 524
269. Third and Fourth Ventricles ........ 527
270. Upper Surface of the Cerebellum ...... 530
271. Under Surface of the Cerebellum . . . . - . . 531
272. Vertical Section of the Cerebellum ..... Arnold 533
Cranial Nerves.
273. Optic Nerves and Optic Tracts ....
274. Course of the Fibres in the Optic Commissure
275. Nerves of the Orbit, seen from above ....
276. Nerves of the Orbit and Ophthalmic Ganglion, side view
277. Course and Connections of the Facial Nerve in the Temporal Bone
278. Nerves of the Scalp, Face, and Side of the Neck
279. Hypoglossal Nerve, Cervical Plexus, and their Branches . .
280. Distribution of the Second and Third Divisions of the Fifth Nerve i
and Submaxillary Ganglion .... J
281. Spheno-Palatine Ganglion and its Branches
282. Otic Ganglion and its Branches ....
283. Origin of the Eighth Pair, their Ganglia and Communications
284. Course and Distribution of the Eighth Pair of Nerves
Bowman
After Arnold
After Arnold
After Bidder
After Arnold
Bendz
536
537
538
539
540
542
544
■After Arnold 549
553
554
555
556
Spinal Nerves.
285. Plan of the Brachial Plexus ....
286. Cutaneous Nerves of Upper Extremity, anterior view
287. Cutaneous Nerves of Upper Extremity, posterior view
288. Nerves of the Upper Extremity, front view
289. Supra-scapular, Circumflex, and Musculo-spiral Nerves
290. Lumbar Plexus and its Branches
291. Cutaneous Nerves of Lower Extremity, front view •
292. Nerves of the Lower Extremity, front view
293. Cutaneous Nerves of Lower Extremity, posterior view
294. Nerves of the Lower Extremity, posterior view
295. Plantar Nerves ......
296. Sympathetic Nerve .....
. 567
. 569
. 570
. 572
. 574
Altered from Quain 579
. 581
. 581
. 587
. 587
. 589
. 593
Organs of Sense.
297. Sectional View of the Skin, magnified .......
298. Upper Surface of the Tongue ........
299. Three kinds of Papillae of the Tongue, magnified . . Bowman
300. Cartilages of the Nose ....... Arnold
301. Bones and Cartilages of Septum of Nose, right side . . . do.
302. Nerves of Septum of Nose, right side ..... do.
303. Vertical Section of the Eyeball, enlarged . . ...
304. Choroid and Iris, enlarged ..... Altered from Zinn
305. Veins of the Choroid, enlarged ...... Arnold
306. Arteries of the Choroid and Iris, enlarged . . . .do.
307. Arteria Centralis Betinae, Yellow Spot, etc., the anterior half of the Eyeball being
removed, enlarged .....••••
308. Crystalline Lens, hardened and divided, enlarged . . . Arnold
309. Meibomian Glands, etc., seen from the Inner Surface of the Eyelids . do.
310. Lachrymal Apparatus, right side .......
311. Pinna or Auricle, outer surface ........
312. Muscles of the Pinna ....... Arnold
602
608
608
611
612
614
615
617
618
619
621
624
626
627
629
630
LIST OP ILLUSTRATIONS
XXXI
Scarpa
PAGE
631
.
633
Arnold
635
Scemmerrmg
638
Arnold
639
Breschet
641
313. Front View of the Organ of Hearing, right side
314. View of Inner Wall of Tympanum, enlarged
315. Small Bones of the Ear, seen from the outside, enlarged
316. Osseous Labyrinth, laid open, enlarged
317. Cochlea laid open, enlarged ....
318. Membranous Labyrinth detached, enlarged
Organs of Digestion and their Appendages.
319. Sectional View of the Nose, Mouth, Pharynx, etc. .
320. Permanent Teeth, external view
321. Temporary or Milk Teeth, external view
322. Vertical Section of a Molar Tooth
323. Vertical Section of a Bicuspid Tooth, magnified . . After Retzius
324 to 329. Development of Teeth ..... Goodsir
330. Salivary Glands ......
331. The Regions of the Abdomen and their contents
332. Reflections of the Peritoneum, as seen in a Vertical Section of •» Altered from
the Abdomen ..... } Quain
333. Mucous Membrane of the Stomach and Duodenum, with the Bile Ducts
334. Muscular Coat of the Stomach .......
335. Minute Anatomy of Mucous Membrane of Stomach . . Dr. Sprott Boyd
336. Two Villi, magnified ........
337. Patch of Peyer's Glands, from the lower part of the Ileum
338. A portion of Peyer's Glands, magnified . . . . Boehm
339. Caecum and Colon laid open, to show the Ilio-caecal Valve
340. Minute Structure of Large Intestine ..... Boehm
341. Liver, upper surface ........
342. Liver, under surface ........
343. Longitudinal section of an Hepatic Vein .... Kieman
344. Longitudinal section of a small Portal Vein and Canal . . • do.
345. Transverse section of a small Portal Canal and its vessels . . do.
346. Pancreas and its Relations ........
347. Transverse section of the Spleen, showing the Tubercular Tissue, and the Splenic
Vein and its branches ........
348. Malpighian Corpuscles, and their Relation with the Splenic Artery and its branches
349. One of the Splenic Corpuscles, showing its Relations with flic Bloodvessels .
350. Transverse section of the Human Spleen, showing the distribution of the Splenic
Artery and its branches ........
644
645
647
648
648
650
054
658
660
664
665
666
669
670
670
671
674
676
677
679
679
680
683
685
686
687
688
Organs of Circulation.
351. *Front view of the Thorax, showing the relation of the Thoracic Viscera to the walls
of the Chest .......... 690
352. Right Auricle and Ventricle laid open, the anterior walls of both being removed . 692
353. Left Auricle and Ventricle laid open, the anterior walls of both being removed . 696
354. Plan of the Fcetal Circulation ........ 700
, Organs of Voice and Eespiration.
355. Side view of the Thyroid and Cricoid Cartilages
356. Cartilages of the Larynx, posterior view ....
357. *Larynx and adjacent parts, seen from above ....
358. *Vertical section of the Larynx and upper part of the Trachea
359. Muscles of Larynx, side view, right Ala of Thyroid Cartilage removed
360. Interior of the Larynx, seen from above, enlarged
361. Front view of Cartilages of Larynx, the Trachea and Bronchi
Willis
703
704
706
707
709
709
711
xxxn
LIST OF ILLUSTRATIONS.
362. *Transverse section of the Trachea, just above its Bifurcation, with a bird's-eye view
of the interior ........
363. Surgical Anatomy of the Laryngotracheal Region ....
364. Transverse section of the Thorax, showing the relative position of the Yiscera, and
the reflections of the Pleura ......
365. *Front view of the Thorax, showing the relation of the Thoracic Viscera to the walls
of the Chest . . . . . .
366. Front view of the Heart and Lungs ......
712
714
715
717
718
The Urinary and Generative Organs.
367. Vertical section of the Kidney ....
368. Plan to show the minute structure of the Kidney . . . Bowman
369. Vertical section of Bladder, Penis, and Urethra • .
370. Bladder and Urethra laid open, seen from above
371. Testis in situ, the Tunica Vaginalis having been laid open
372. Vertical section of the Testicle, to show the arrangement of the ducts
373. Base of the Bladder, with the Vasa Deferentia and Vesiculae Seminales Haller
374. Vulva and External Female Organs of Generation .....
375. Section of Female Pelvis, showing position of Viscera ....
376. Uterus and its Appendages, anterior view .... Wilson
377. *Section of the Ovary of a Virgin, showing the Stroma and Graafian Vesicles
378. *Section of the Graafian Vesicle .... After Van Baer
379. *Ovum of the Sow ...... After Barry
380. Inguinal Hernia, Superficial Dissection .....
381. Inguinal Hernia, showing the Internal Oblique, C remaster, and Spermatic Canal
382. Inguinal Hernia, showing the Transversalis Muscle, the Transversalis Fascia, and
the Internal Abdominal Ring ....
383. Femoral Hernia, Superficial Dissection
384. Femoral Hernia, showing Fascia Lata, and Saphenous Opening
385. Femoral Hernia, Iliac Portion of Fascia Lata removed, and Sheath of Femoral Vessels
and Femoral Canal exposed
386. Hernia ; the Relations of the Femoral and Internal Abdominal Rings, seen from
within the Abdomen, right side ......
387. 388. Variations in Origin and Course of Obturator Artery
389. Plan of Dissection of Perineum and Ischio-rectal Region
390. Perineum; the Integument and Superficial Layer of Superficial Fascia reflected
391. The Superficial Muscles and Vessels of the Perineum . .
392. Deep Perineal Fascia ; on the Left Side the Anterior Layer has been removed
393. A view of the Position of the Viscera at the Outlet of the Pelvis
394. A transverse section of the Pelvis, showing the Pelvic Fascia . After Wilson
395. Side view of the Pelvic Viscera of the Male Subject, showing the Pelvic and Perineal
Fasciae ..........
725
725
729
732
740
741
743
746
748
753
753
753
754
759
761
763
767
768
770
772
772
776
778
779
780
783
784
785
ANATOMY,
DESCRIPTIVE AND SURGICAL.
Osteology.
In the construction of the human body, it would appear essential, in the first
place, to provide some dense and solid texture capable of forming a framework
for the support and attachment of the softer parts of the frame, and of forming
cavities for the protection of the more important vital organs; and such a
structure we find provided in the various bones, which form what is called the
Skeleton (oxexxu>, to dry tip).
Structure and Physical Properties of Bone. Bone is one of the hardest structures
of the animal body ; it possesses also a certain degree of toughness and elasticity.
Its color, in a fresh state, is of a pinkish-white externally, and deep red within.
On examining a section of any bone, it is seen to be composed of two kinds
of tissue, one of which is dense and compact in texture, like ivory; the other
consisting of slender fibres and lamellae, which join to form a reticular structure;
this, from its resemblance to lattice-work, is called cancellated. The compact
tissue is always placed on the exterior of a bone; the cancellous tissue is always
internal. The relative quantity of these two kinds of tissue varies in different
bones, and in different parts of the same bone, as strength or lightness is requisite.
Close examination of the compact tissue shows it to be extremely porous, so that
the difference in structure between it and the cancellous tissue depends merely
upon the different amount of solid matter, and the size and number of the spaces
in each; in the compact tissue the cavities being small, and the solid matter
between them abundant, whilst in the cancellous tissue the spaces are large, and
the solid matter diminished in quantity.
Chemical Analysis. Bone consists of an organic or animal, and an inorganic
or earthy material, intimately combined together: the animal matter giving to
bone its elasticity and toughness, the earthy part its hardness and solidity. The
animal constituent may be separated from the earthy by steeping bone in a dilute
solution of nitric or muriatic acid : by this process the earthy constituents are
gradually dissolved out, leaving a tough semi-transparent substance, which retains,
in every respect, the original form of the bone. This is often called cartilage,
but differs from it in being softer, more flexible, and, when boiled under a high
pressure, it is almost entirely resolved into gelatine. Cartilage does, however,
form the animal basis of bone in certain parts of the skeleton. Thus, according
to Tomes and De Morgan, it occurs in the petrous part of the temporal bone; and,
according to Dr. Sharpey, on the articular ends of adult bones, lying underneath
the natural cartilage of the joint. The earthy constituent may be obtained by
subjecting a bone to strong heat in an open fire with free access of air. By these
means the animal matter is entirely consumed, the earthy part remaining as a
white brittle substance still preserving the original shape of the bone. Both
constituents present the singular property of remaining unaltered in chemical
composition after a lapse of centuries.
3
34
OSTEOLOGY.
The organic constituent of bone forms about one-third, or 33.3 per cent.; the
inorganic matter, two-thirds, or 66.7 per cent. : as is seen in the subjoined analysis
by Berzelius: —
Organic Matter,
Gelatine and Bloodvessels
. 33.30
1 Phosphate of Lime .
. 51.04
Inorganic
Carbonate of Lime .
. 11.30
or
Fluoride of Calcium
. 2.00
Earthy Matter,
Phosphate of Magnesia
. 1.16
V Soda and Chloride of Sodium .
. 1.20
100.00
Some chemists add to this about one per cent, of fat.
The relative proportions of the two constituents of bone are found to differ in
different hones of the skeleton, as shown by Dr. Owen Eees. Thus, the bones of
the head, and the long bones of the extremities, contain more earthy matter than
those of the trunk; and those of the upper extremity somewhat more than the
corresponding bones of the lower extremity. The humerus contains more earthy
matter than the bones of the forearm ; and the femur more than the tibia and
fibula. The vertebras, ribs, and clavicle contain nearly the same proportion of
earthy matter. The metacarpal and metatarsal bones contain about the same
proportion as those of the trunk.
Much difference exists in the analyses given by chemists as to the proportion
between the two constituents of bone at different periods of life. According to
Schreger, and others, there is considerable increase in the earthy constituents of
the bones with advancing years. Dr. Eees states that this is especially marked
in the long bones, and the bones of the head, which, in the foetus, do not contain
the excess of earthy matter found in those of the adult. But the bones of the
trunk in the foetus, according to this analyst, contain as much earthy matter as
those of the adult. On the other hand, the analyses of Stark and Yon Bibra
show that the proportions of animal and earthy matter are almost precisely the
same at different periods of life. According to the analyses of Yon Bibra,
Yalentin, and Dr. Kees, the compact substance contains more earthy matter than
the cancellous. The comparative analysis of the same bones in both sexes shows
no essential difference between them.
There are facts of some practical interest, bearing upon the difference which
seems to exist in the amount of the two constituents of bone at different periods
of life. Thus, in the child, where the animal matter predominates, it is not
uncommon to find, after an injury to the bones, that they become bent or only
partially broken, from the large amount of flexible animal matter which they
contain. Again, also in aged people, where the bones contain a large proportion
of earthy matter, the animal matter at the same time being deficient in quantity
and quality, the bones are more brittle, their elasticity is destroyed, and, hence,
fracture takes place more readily. Some of the diseases, also, to which bones
are liable, mainly depend on the disproportion between the two constituents of
bone. Thus, in the disease called rickets, so common in the children of scrofulous
parents, the bones become bent and curved, either from the superincumbent
weight of the body, or under the action of certain muscles. This depends upon
some deficiency of the nutritive system, by which bone becomes minus its normal
proportion of earthy matter, whilst the animal matter is of unhealthy quality.
In the vertebra of a rickety subject, Dr. Bostock found in 100 parts 79.75 animal,
and 20.25 earthy matter.
Form of Bones. The various mechanical purposes for which bones are employed
in the animal economy require them to be of very different forms. All the scien-
tific principles of Architecture and Dynamics are more or less exemplified in the
construction of this part of the human body. The power of the arch in resisting
^
GENERAL ANATOMY OF BONE. 35
superincumbent pressure is well exhibited in various parts of the skeleton, such
as the human foot, and more especially in the vaulted roof of the cranium.
Bones are divisible into four classes : Long, Short, Flat, and Irregular.
The Long Bones are found chiefly in the limbs, where they form a system of
levers, which have to sustain the weight of the trunk, and to confer extensive
powers of locomotion. A long bone consists of a lengthened cylinder or shaft,
and two extremities. The shaft is a hollow cylinder, the walls consisting of dense
compact tissue of great thickness in the middle, and becoming thinner towards 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 purposes 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,
the clavicle, humerus, radius, ulna, femur, tibia, fibula, metacarpal and metatarsal
bones, and the phalanges.
Short Bones. Where a part is intended for strength and compactness, and the
motion 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 com-
pressed, such as the bones of the carpus and tarsus. These bones, in their struc-
ture, are spongy throughout, excepting at their surface, where there is a thin crust
of compact substance.
Flat Bones. Where the principal requirement is either extensive protection, or
the provision of broad surfaces for muscular attachment, we find the osseous struc-
ture remarkable for its slight thickness, becoming expanded into broad flat plates,
as is seen in the bones of the skull and shoulder-blade. These bones are composed
of two thin layers of compact tissue, inclosing 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 one is thick and tough, the
inner one thinner, denser, and more brittle, and hence termed the vitreous table.
The intervening cancellous tissue is called the diploe. The flat bones are, the
occipital, parietal, frontal, nasal, lachrymal, vomer, scapulee, ossa innominata, sternum,
and ribs.
The Irregular or Mixed bones are such as, from their peculiar 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 vertebrse, sacrum, coccyx,
temporal, sphenoid, ethmoid, superior maxillary, inferior maxillary, 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.
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 drtoyveis, an
excrescence) ; but if such process is developed as a separate piece from the rest of
the bone to which it is afterwards joined, it is termed an epiphysis (from hnlyvais,
an accretion).
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, or line.
The non-articular depressions are also of very variable form, and are described
as fossre, grooves, furrows, fissures, notches, etc. These non-articular eminences
and depressions serve to increase the extent of surface for the attachment of liga
3G OSTEOLOGY.
inents and muscles, and are usually well marked in proportion to the muscularity
of the subject.
Microscojjcc Structure. If a thin transverse section from the shaft of a long
bone be examined with a power of about 20 diameters, a number of aper-
tures, surrounded by a series of concentric rings, are observed, with small, dark
spots grouped around them, also in a concentric manner. The apertures are
sections of the Haversian canals (so called after their discoverer, Clopton Havers);
the concentric rings are sections of the lamellae, which are developed around the
Haversian canals ; the dark spots are small cavities in the substance of the bone,
called lacunse.
The Haversian canals are channelled out of the compact substance for the pur-
pose of conveying bloodvessels for its nutrition. They vary in size from the
2^0 to the tj^'ott °f an mcn m diameter, the average size being about z\-$. They
are generally round or oval, sometimes angular. Those nearest to the outer sur-
face, where the bone is most compact, are very small ; but, towards the medullary
canal, they gradually acquire a larger size, and open into it, or into the cells of tlm
cancellous tissue. The Haversian canals are lined by a delicate membrane con-
tinuous with the periosteum ; the smallest canals contain a single capillary vessel ;
those larger in size contain a network of vessels: whilst the largest contain blood-
vessels and marrow. If a thin longitudinal section of the shaft of a long bone be
examined, the Haversian canals will be found to run in the long axis of the bone,
and parallel with each other, communicating freely by transverse or oblique canals,
so as to form, for the most part, rectangular meshes. Some of these canals open
on the outer surface, to admit bloodvessels from the periosteum ; others communi-
cate with the medullary canal, receiving bloodvessels from the interior of this part.
By this means, the Haversian canals establish a free communication between the
bloodvessels of the periosteum, and those of the medullary membrane.
If a higher power is now applied to the same transverse section, each Haversian
canal appears surrounded by a series of concentric rings, varying in number from
eight to fifteen ; these rings are termed the lamellve, and their appearance is pro-
duced by transverse sections of concentric layers of bone that have been developed
around the Haversian canal, the last formed layer being deposited on that surface
next to the bloodvessel. This concentric arrangement is not complete around all
the canals; for here and there one set of lamellae may be seen ending between two
adjacent ones. Besides the lamellae surrounding the Haversian canals, some are
disposed parallel with the outer and inner surfaces of the bone ; these are termed
circumferential lamellae, and may be considered as concentric with the medullary
canal. Others, again, penetrate between the Haversian systems ; these are termed
interstitial lamellae. Each Haversian canal, together with its concentric lamellae
of bone, lacunae, etc., is called an Haversian system, the bloodvessel contained in
the central canal being the source of nutrition to the lamellae which surround it.
Nearly the whole of the compact tissue is made up of these Haversian systems,
each one being, to a certain extent, independent of the rest. In a longitudinal
section, the lamellae are seen running in lines parallel with the Haversian canal
which they surround, except when the section passes transversely or obliquely
across a canal, in which case an appearance is seen, somewhat similar to that
observed in a transverse section. This lamellated structure may be easily demon-
strated on a piece of bone softened in dilute acid, when the lamellae may be peeled
from the surface of the bone in a longitudinal direction. According to Dr. Sharpey,
the lamella3, in structure, consist of fine transparent fibres decussating each other,
so as to form a delicate network, the fibres apparently coalescing at their point
of junction. The lamellae are perforated, in certain situations, by bundles of
fibres which penetrate them in a more or less oblique direction, serving to securely
approximate the several plates. The lamellae are also perforated by numerous
minute apertures placed at regular distances apart, which are, probably, transverse
sections of the canaliculi. In this fibrous basis of the lamellae, the inorganic
elements of bone are intimately united.
GENERAL ANATOMY OF BONE. 37
A transverse section of compact bone sometimes exhibits certain vacuities or
spaces, termed, by Messrs. Tomes and De Morgan, Haversian spaces. These
spaces are found at al\ periods of life, but especially in young and growing bones.
They are characterized by an irregular or jagged outline, and are apparently
produced by the absorption of parts of several Haversian systems, which have
been, to a greater or less extent, removed in order to form them. These spaces
may exist in various conditions: in some, the process of absorption is evidently
going on; in others, the spaces are lined by newly-formed lamellae which fill
up the peripheral portion of the space; in others, the lamellas fill in the whole
of the space, leaving a Haversian canal in the centre. It would thus appear,
that portions of the Haversian systems are, from time to time, removed by
absorption, and a new system of lamellae re-formed in place of those previously
existing. Sometimes, these spaces may be seen filled in, at one part, by the
deposition of lamellas; while, at another part, they are extending themselves by
absorption.
We have already said, that the dark spots seen in and between the lamellae,
arranged in concentric circles around the Haversian canals, are the lacunse.
They are minute cavities existing in the osseous substance, having numerous fine
^ tubes called canaliculi issuing from all parts of their circumference. In fresh
bones, each lacuna contains a delicate cell, with pellucid contents, and a single
nucleus ; and from the cell numerous fine processes are given off, which fill the
canaliculi. These are the bone cells, discovered by Virchow. The lacunae are
oval flattened spaces, lying parallel to the direction of the lamellae. The canaliculi
issuing from them are extremely minute, their diameter ranging from T1kw to
5 noun °f aT1 inch. They communicate freely with the canaliculi of adjoining
lacunae, some opening into the Haversian canals, or in the cancelli of the spongy
substance, and some upon the free surface of the bone. By this communication
between the lacunae and canaliculi traversing the entire substance of the bone,
the plasma of the blood is carried into every part.
Vessels of Bone. The bloodvessels of bone are very numerous. Those of the
compact tissue are derived from a close and dense network of vessels, which ramify
in a fibrous membrane termed the periosteum, which covers the surface of the bone
in nearly every part. From this membrane, vessels pass through the minute orifices
in the compact tissue, running through the canals which traverse its substance.
The cancellous tissue is supplied in a similar way, but by a less numerous set of
larger vessels, which, perforating the outer compact tissue, are distributed to the
cavities of the spongy portion of the bone. In the long bones, numerous apertures
may be seen at the ends near the articular surfaces, some of which give passage to
the arteries referred to; but the greater number, and these are the largest of them,
are for the veins of the cancellous tissue which run separately from the arteries.
The medullary canal in the shafts of the long bones is supplied by one large
artery, — or sometimes more, — which enters the bone at the nutritious foramen
(situated, in most cases, near the centre of the shaft), and perforates obliquely the
compact substance. This vessel, usually accompanied by one or two veins, sends
branches upwards and downwards, to supply the medullary membrane, which
lines the central cavity and the adjoining canals. The ramifications of this vessel
anastomose with the arteries both of the cancellous and compact tissues. In most
of the flat, and in many of the short spongy bones, one or more large apertures
are observed, which transmit, to the centre of the bone, vessels which correspond
to the medullary arteries and veins.
The veins emerge from the long bones in three places (Kolliker). 1. By a large
vein which accompanies the nutrient artery; 2. by numerous large and small veins
at the articular extremities; 3. by many small veins which arise in the compact
substance. In the flat cranial bones, the veins are large, very numerous, and run
in tortuous canals in the diploic tissue, the sides of which are constructed of a thin
lamella of bone, perforated here and there for the passage of branches from the
adjacent cancelli. The veins thus inclosed and supported by the osseous structure,
38 OSTEOLOGY.
have exceedingly thin coats; and when the bony structure is divided, thej
remain patulous, and do not contract in the canals in which they are. contained.
Hence the constant occurrence of purulent absorption after amputation, in those
cases where the stump becomes inflamed, and the cancellous tissue is infiltrated
and bathed in pus.
Lymphatic vessels have been traced, by Cruikshank, into the substance of bone,
but Kolliker doubts their existence. Nerves are distributed freely to the perios-
teum, and accompany the nutritious arteries into the interior of the bone. They
are said, by Kolliker, to be most numerous in the articular extremities of the
long bones, in the vertebrae, and the larger flat bones.
Periosteum. The bones are covered by a tough fibrous membrane, the periosteum,
which adheres to their surface in nearly every part, excepting at their cartilaginous
extremities, and where strong tendons are attached. ,It is highly vascular; and,
from it, numerous vessels pass into minute orifices which cover the entire surface
of the bone. It consists of two layers closely united together; the outer one
formed chiefly of connective tissue, and occasionally a few fat-cells ; the inner one,
of elastic fibres of the finer kind, which form dense elastic membranous networks,
superimposed in several layers (Kolliker). In young bones, this membrane is
thick, very vascular, intimately connected at either end of the bone with the
epiphysal cartilage ; but less closely connected with the shaft, from which it is
separated by a layer of soft blastema, in which ossification proceeds on the exterior
of the young bone. Later in life, the periosteum is thinner, less vascular, and
more closely connected with the adjacent bone, this adhesion growing stronger as
age advances. The periosteum serves as a nidus for the ramification of the vessels
previous to their distribution in the bone ; hence the liability of bone to exfolia-
tion or necrosis, when, from injury, it is denuded of this membrane.
Marrow. The medullary canal of adult long bones, the cavities of the cancellous
tissue, and the larger Haversian canals, are filled with a substance called marrow,
and lined by a highly vascular areolar tissue, the medullary membrane, or internal
periosteum. It is by means of the vessels which ramify through this membrane,
that the nourishment of the medulla and contiguous osseous tissue is effected.
The marrow differs in composition at different periods of life, and in different
bones. In young bones, it is a transparent reddish fluid, of tenacious consistence,
free from fat; and contains numerous minute roundish polynucleated cells. In
the shafts of adult long bones, the marrow is of a yellow color, and contains, in
100 parts, 96.0 fat, 1.0 areolar tissue and vessels, and 3.0 of fluid with extractive
matters ; whilst, in the flat and short bones, in the articular ends of the long bones,
in the bodies of the vertebras, the base of the cranium, and in the sternum and
ribs, it is of a red color, and contains, in 100 parts, 75.0 water, and 25.0 solid
matter, consisting of albumen, fibrin, extractive matter, salts, and a mere trace of
fat. It consists of fat-cells with a large quantity of fluid, containing numerous
polynucleated cells, similar to those found in foetal marrow.
Development of Bone. From the peculiar uses to which bone is applied in
forming a hard skeleton or framework for the softer materials of the body, and in
inclosing and protecting some of the more important vital organs, we find its
development takes place at a very early period. Hence, the parts that appear
soonest in the embryo are the vertebral column and the skull, the great central
column, to which the other parts of the skeleton are appended. At an early period
of embryonic life, the parts destined to become bone consist of a congeries of cells,
connected together by an amorphous blastema which constitutes the simplest form
of cartilage. This temporary cartilage, as it is termed, is an exact miniature of
the bone which, in due course, is to take its place ; and as the process of ossification
is slow, and not completed until adult life, it increases in bulk by an interstitial
development of new cells. The next step in this process is the ossification of the
intercellular substance, and of the cells composing the cartilage. Ossification
commences in the interior of the cartilage at certain points, called points or centres
of ossification, from which it extends into the surrounding substance. This mode
GENERAL ANATOMY OF BONE. 39
of ossification is called intra-cartilaginous, to distinguish it from that which takes
{)lace in a membranous tissue, quite different in its nature from cartilage. The
atter mode of ossification is called intra-membranous. Examples of it are seen,
according to Kolliker, in the upper half of the expanded portion of the occipital
bone ; the parietal and frontal bones ; the squamous portion and tympanic ring of
the temporal bone ; the internal lamella of the pterygoid process of the sphenoid ;
the cornua sphenoidalia ; in all the bones of the face, excepting the inferior turbi-
nated ; and, according to Brack, in the clavicle.
The period of ossification is different in different bones. The order of succes-
sion may be thus arranged (Kolliker) : —
In the second month, first, in the clavicle, and lower jaw (fifth to seventh week);
then, in the vertebrae, humerus, femur, the ribs, and the cartilaginous portion of
the occipital bone.
At the end of the second, and commencement of the third month, the frontal
bone, the scapula, the bones of the forearm and leg, and upper jaw, make their
appearance.
In the third month, the remaining cranial bones, with few exceptions, begin to
ossify, the metatarsus, the metacarpus, and the phalanges.
In the fourth month, the iliac bones, and the ossicula auditus.
In the fourth or fifth month, the ethmoid, sternum, pubis, and ischium.
From the sixth to the seventh month, the calcaneum, and astragalus.
In the eighth month, the hyoid bone.
At birth, the epiphyses of all cylindrical bones, occasionally with the exception
of those of the femur and tibia ; all the bones of the carpus ; the five smaller
ones of the tarsus ; the patella ; sesamoid bones ; and the last pieces of the coccyx,
are still unossified.
From the time of birth to the fourth year, osseous nuclei make their appearance
also in these parts.
At twelve years, in the pisiform bone.
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 towards
the circumference. In the long bones, there is a central point of ossification for the
shaft or diaphysis ; and one or more for each extremity, the epiphyses. That for the
shaft is the first to appear ; those for the extremities appear later. For a long period
after birth, a thin layer of unossified cartilage remains between the diaphysis and
epiphyses, until their growth is finally completed, their junction taking place either
at the period of puberty, or towards the end of the period of growth. The union of
the epiphyses with the shaft takes place in the inverse order to that in which their
ossification began ; for, although ossification commences latest in those epiphyses
towards which the nutritious artery in the several bones is directed, they become
joined to the diaphyses sooner than the epiphyses at the opposite extremity, with
the exception of the fibula, the lower end of which commences to ossify at an
earlier period than the upper end, but, nevertheless, is joined to the shaft earliest.
The order in which the epiphyses become united to the shaft appears to be
regulated by the direction of the nutritious artery of the bone. Thus the arteries
of the bones of the arm and forearm are directed towards the elbow, and the
epiphyses of the bones forming this joint become united to the shaft before those
at the opposite extremity. In the lower extremities, on the contrary, the
nutritious arteries pass in a direction from the knee; that is upwards in the femur,
downwards in the tibia and fibula ; and in them it is observed, that the upper
epiphysis of the femur, and the lower epiphyses of the tibia and fibula, become
first united to the shaft.
Where there is only one epiphysis, the medullary artery is directed towards that
end of the bone where there is no additional centre : as, towards the acromial end
in the clavicle ; towards the distal end of the metacarpal bone of the thumb and great
toe; and towards the proximal end of the other metacarpal and metatarsal bones.
A knowledge of the exact periods when the epiphyses become joined to the
tJ^sI.
40
OSTEOLOGY.
shaft aids the surgeon in the diagnosis of many of the injuries to which the joints
are liable ; for it not unfrequently happens that, on the application of severe force
to a joint, the epiphyses become separated from the shaft, and such injuries may
be mistaken for fracture.
Growth of Bone. Increase in the length of a bone is provided for by the deve-
lopment of new bone in the cartilage at either end of the shaft (diaphysis); and in
the thickness, by the deposition of soft ossifying blastema in successive layers
upon the inner surface of the periosteum.
The entire skeleton in an adult consists of 204 distinct bones. These are —
Vertebral column (sacrum and coccyx included)
26
Cranium ........
8
Ossicula auditus ......
6
Face
14
Os hyoides, sternum, and ribs ....
26
Upper extremities ......
64
Lower extremities
60
204
In this enumeration, the patellae and other sesamoid bones, as well as the
Wormian bones, are excluded, as are also the teeth, which differ from bone both
in structure, development, and mode of growth.
THE SPINE.
The Spine is a flexuous column, formed of a series of bones called Vertebrse.
The Vertebrae are thirty-three in number, exclusive of those which form the skull,
and have received the names cervical, dorsal lumbar, sacral, and coccygeal, according
to the position which they occupy ; seven being found in the cervical region, twelve
in the dorsal, five in the lumbar, five in the sacral, and four in the coccygeal.
This number is sometimes found increased by an additional segment in one
region, or the number may be diminished in one region, the deficiency being
supplied by an additional segment in another. These observations do not apply
to the cervical portion of the spine, the number of segments forming which is
seldom increased or diminished.
The Vertebrae in the three uppermost regions of the spine are separate segments
throughout the whole of life ; 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.
General Characters of a Vertebra.
Each vertebra consists of two essential parts, an anterior solid segment or
body, and a posterior segment, the arch. The arch is formed of two pedicles
and two laminae, supporting seven processes ; viz., four articular, two transverse,
and one spinous process.
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 behind these
a hollow cylinder for the protection of the spinal cord. The different segments
are connected together by means of the articular processes, and 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 con-
stituent parts must now be separately examined.
/
CHARACTERS O^ THE CERVICAL VERTEBRJE.
41
The Body is the largest and most solid part of a vertebra. Above and below, it
is slightly concave, presenting a rim around its circumference ; and its surfaces are
rough, for the attachment of the intervertebral fibro-cartilages. In front it is convex
from side to side, concave from above downwards. Behind, flat from above down-
wards and slightly concave from side to side. Its anterior surface is perforated by
a few small apertures, for the passage of nutrient vessels ; whilst on the posterior
surface is a single irregular-shaped aperture, or occasionally several large apertures,
for the exit of veins from the body of the vertebra, the vense basis vertebrse.
The Pedicles project backwards, 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.
The concavities above and below the pedicles are the intervertebral notches ; they
are four in number, two on each side, the inferior ones being generally the deeper.
When the vertebrae are articulated, the notches of each contiguous pair of bones
form the intervertebral foramina, which communicate with the spinal canal and
transmit the spinal nerves.
The Laminse are two broad plates of bone, which complete the vertebral arch
behind, inclosing a foramen which serves for the protection of the spinal cord ;
they are connected to the body by means of the pedicles. Their upper and lower
borders are rough, for the attachment of the ligamenta subjlava.
The Articular Processes, four in number, two on each side, spring from the
junction of the pedicles with the laminae. The two superior project upwards,
their articular surfaces being directed more or less backwards, the two inferior
project downwards, their articular surfaces looking more or less forwards.
The Spinous Process projects backwards from the junction of the two laminae,
and serves for the attachment of muscles.
The Transverse Processes, two in number, project one at each side from the
point where the articular processes join the pedicle. They also serve for the
attachment of muscles.
Characters of the Cervical Vertebrae.
The Body (fig. 1) is smaller than in any other region of the spine, and broader
from side to side than from before backwards. The anterior and posterior surfaces
are flattened and of equal depth ; the former is placed on a lower level than the
Fig. 1. — A Cervical Vertebra.
Anterior Talercle of Trans.Troc
foramen fm- Vertebral Art
TostencrTulcrch of Trans . P roc,
Transverse Process.
^Superior Articular Prores*.
-Life riorArtlcala r Srccest.
latter, and its inferior border is prolonged downwards 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 being convex from
side to side, concave from before backwards, and presenting laterally a shallow
concavity, which receives the corresponding projecting lip of the adjacent verte-
bra. The pedicles are directed obliquely outwards, and the superior intervertebral
42
OSTEOLOGY.
notches are deeper, but narrower, than the inferior. The laminse are narrow,
long, thinner above than below, and overlap each other; inclosing the spinal
foramen, which is very large, and of a triangular form. The spinous processes
are short, bifid at the extremity, to afford greater extent of surface for the attach-
ment of muscles, the two divisions being often of unequal size. They increase
in length from the fourth to the seventh. The transverse processes are short,
directed downwards, outwards, and forwards, are bifid at their extremity, and
marked by a groove along their upper surface, which runs downwards and out-
wards from the superior intervertebral notch, and serves for the transmission of
one of the cervical nerves. The transverse processes are pierced at their base by
a foramen, for the transmission of the vertebral artery, vein, and plexus of nerves.
Each process is formed by two roots ; the anterior root arises from the side of the
body, and corresponds to the ribs ; the posterior root springs from the junction of
the pedicle with the lamina, and corresponds with the transverse processes in the
dorsal region. It is by the junction of these two processes, that the vertebral
foramen is formed. The extremities of each of these roots form the anterior and
posterior tubercles of the transverse processes. The articular processes are oblique:
the superior are of an oval form, flattened, and directed upwards and backwards;
the inferior downwards and forwards.
The peculiar vertebrae in the cervical region are the first or Atlas; the second or
Axis; and the seventh or Vertebra prorninens. The great modifications in the form
of the atlas and axis are- to admit of the nodding and rotatory movements of the
head.
The Atlas (fig. 2) is so named from supporting the globe of the head. The chief
Fig. 2. — 1st Cervical Vertebra or Atlas.
Tubercle-
Trans. Prooc
Toramen for
Vertebral Art?.
Groove fcr Verz>e£. Art ?
ajid'l.'-' Cerv.Nerva
Spin. Proc,
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
the second vertebra, the parts corresponding to the pedicles pass in front and
join to form the anterior arch. The atlas consists of an anterior arch, a posterior
arch, and two lateral masses. The anterior arch forms about one-fifth of the
bone ; its anterior surface is convex, and presents about its centre a tubercle, for
the attachment of the Longus colli muscle ; posteriorly it is concave, and marked
by a smooth oval or circular facet, for articulation with the odontoid process of
the axis. The posterior arch forms about two-fifths of the circumference of the
bone ; it terminates behind in a tubercle, which is the rudiment of a spinous
process, and gives origin to the Eectus capitis posticus minor. The diminutive
size of this process prevents any interference in the movements between it and
the cranium. The posterior part of the arch presents above a rounded edge ;
whilst in front, immediately behind each superior articular process, is a groove,
sometimes converted into a foramen by a delicate bony spiculum which arches
CERVICAL VERTEBRAE. 43
backwards 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 before them, as in the other
vertebne. Thej 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 backwards and inwards. They also transmit the sub-occipital nerves.
On the under surface of the posterior arch, in the same situation, are two other
grooves, placed behind the lateral masses, and representing the inferior interver-
tebral notches of other vertebrae ; they are much less marked than the superior.
The lateral masses are the most bulky and solid parts of the atlas, in order to
support the weight of the head ; they present two articulating processes above,
and two below. The two superior are of large size, oval, concave, and approach
towards one another in front, but diverge behind ; they are directed upwards,
inwards, and a little backwards, forming a kind of cup for the condyles of the
occipital bone, and are admirably adapted to the nodding movements of the head.
Not unfrequentl}7' they are partially subdivided by a more or less deep indentation
which encroaches upon each lateral margin ; the inferior articular processes are
circular in form, flattened, or slightly concave, and directed downwards, inwards,
and a little backwards, articulating with the axis, and permitting the rotatory
movements. Just below the inner margin of each superior articular surface, is a
small tubercle, for the attachment of a ligament which, stretching across the ring
of the atlas, divides it into two unequal parts ; the anterior or smaller segment
receiving the odontoid process of the axis, the posterior allowing the transmission
of the spinal cord and its membranes. This part of the spinal canal is of con-
siderable size, to afford space for the spinal cord ; and hence lateral displacement
of the atlas may occur without compression of the spinal cord. (This ligament
and the odontoid process are marked in figure 2 in dotted outline.) The trans-
verse processes are of large size, for the attachment of special muscles which
assist in rotating the head — long, not bifid, perforated at their base by a canal
for the vertebral artery, which is directed from below, upwards and backwards.
The Axis (fig. 3) is so named from forming the pivot upon which the head
Fig. 3. — 2d Cervical Vertebra or Axis.
Odontoid JPros ,
Rovgh Surf, for CAee'A Lig^-
Artic.Swrf.fer Trant.Ligt •
Spin. Free. J
Artie. Surf.foT Atlas
A— Body
Trant.Proe.
Infer. A. rtic. Pro*.
rotates. The most distinctive character of this bone is the strong prominent
process, tooth-like in form (hence the name odontoid), which rises perpendi-
cularly from the upper part of the body. The body is of a triangular form ;
deeper in front than behind, and prolonged downwards anteriorly so as to overlap
the upper and fore part of the adjacent vertebra. It presents in front a median
longitudinal ridge, separating two lateral depressions for the attachment of the
Longi colli muscles. The odontoid process presents two articulating surfaces:
44
OSTEOLOGY.
one in front of an oval form, for articulation with the atlas ; another behind, for
the transverse ligament; the latter frequently encroaches on the sides of the
process ; the apex is pointed. Below the apex this process is somewhat enlarged,
and presents on either side a rough impression for the attachment of the odontoid
or check ligaments, which connect it to the occipital bone ; the base of the process,
where 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 displaced, especially in
children, where the ligaments are more relaxed ; instant death is the result. The
pedicles are broad and strong, especially their anterior extremities which coalesce
with the sides of the body and the root of the odontoid process. The laminae are
thick and strong, and the spinal foramen very large. The superior articular
surfaces are round, slightly convex, directed upwards and outwards, and are
peculiar in being supported on the body, pedicles, and transverse processes. The
inferior articular surfaces, have the same direction as those of the other cervical
vertebras. The superior intervertebral notches are very shallow, and lie behind
the articular processes ; the inferior in front of them, as in the other cervical
vertebras. The transverse processes are very small, not bifid, and perforated by
the vertebral foramen, which is directed obliquely upwards and outwards. 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. 4). The
most distinctive character of this
vertebra is the existence of a very
long, and prominent spinous pro-
cess; hence the name Vertebra
prominens. This process is thick,
nearly horizontal in direction, not
bifurcated, and has attached to it
the ligamentum nuchas. The
transverse process is usually of
large size, especially its posterior
root, its upper surface has usually
a shallow groove, and seldom pre-
sents more than a trace of bifur-
cation at its extremity. The ver-
tebral foramen is sometimes as
large as in the other cervical ver-
tebrae, usually smaller, on one or
both sides, and sometimes want-
On the left side, it occasion -
Pig. 4.
-7th Cervical Vertebra or Vertebra
Prominens.
Bcdy.
msr.
Spinous .Prscj/S
ally gives passage to the vertebral
artery; more frequently the ver-
tebral vein traverses it on both
sides ; but the usual arrangement is for both artery and vein to pass through the
foramen in the transverse process of the sixth cervical.
Characters of the Dorsal Vertebrae.
The bodies of the dorsal vertebrae (fig. 5) resemble those in the cervical and
lumbar regions at the respective ends of this portion of the spine ; but in the
middle of the dorsal region their form is very characteristic, being heart-shaped,
and broader in the antero-posterior than in the lateral direction. They are
thicker behind than in front, flat above and below, convex and prominent in
front, deeply concave 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
DORSAL YERTEBRJE.
45
above, the other below. These are covered with cartilage in the recent state;
and, when articulated with the adjoining vertebrae, form oval surfaces for the
reception of the heads of the corresponding ribs. The pedicles are directed
backwards, and the inferior intervertebral notches are of large size, and deeper
than in any other region of the spine. The laminse are broad and thick, and
the spinal foramen small, and of a circular form. The articular processes are flat,
nearly vertical in direction, and project from the upper and lower part of the
pedicles, the superior being directed backwards and a little outwards and upwards,
the inferior forwards and a little inwards and downwards. The transverse pro-
cesses arise from the same parts of the arch as the posterior roots of the trans-
verse processes in the neck ; they are thick, strong, and of great length, directed
obliquely backwards and outwards, presenting a clubbed extremity, lipped on its
anterior part by a small concave surface, for articulation with the tubercle of a
rib. Besides the articular facet for the rib, two indistinct tubercles may be seen
rising from the extremity of the transverse processes, one' near the upper, the
other near the lower border. In many they are comparatively of small size, and
serve only for the attachment of muscles. But in some animals, they attain con-
siderable magnitude either for the purpose of more closely connecting the seg-
ments of this portion of the spine, or for muscular and ligamentous attachment.
The spinous processes are long, triangular in form, directed obliquely downwards,
and terminate by a tubercular margin. They overlap one another from the fifth,
to the eighth, but are less oblique in direction above and below.
Fig. 5. — A Do i sal Vertebra.
Superior Artie. 1'rocest
jffil
Facet fr Tulercle ofJZii
Demi facet for head cf Eil
Demi facet furliea.d, of Jill
lW Infer. Artie. Froc.
The peculiar dorsal vertebrae are the first, ninth, tenth, eleventh, and twelfth
(fig. 6).
The First Dorsal 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 upper surface of the body is like that of a cervical vertebra,
being broad transversely, concave, and lipped on each side. The articular sur-
faces are oblique, and the spinous process thick, long, and almost horizontal.
The Ninth Dorsal has no demi-facet below. In some subjects, the ninth has
two demi-facets on each side ; then the tenth has a demi-facet at the upper part,
none below.
The Tenth Dorsal has an entire articular facet on each side above ; no demi
facet below.
46
OSTEOLOGY.
In the Eleventh Dorsal, the body approaches in its form and size to the lumbar
vertebras.! 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 dorsal region. The transverse
processes are very short, tubercular at their extremities, and have no articular
facets for the tubercles of the ribs. The spinous process is short, nearly horizontal
in direction, and presents a slight tendency to bifurcation at its extremity.
Fig. 6. — Peculiar Dorsal Vertebrae.
An. entire faeet <t7>ov4
A Demi facet lelow
— A Demi facet aiove
— On* entire farev
n entire facet
Vo facet on Trans.Pror.
•/tts n/ dime/it a r/r
n entire facet
No facet tin.Tra ?is jir.
Infer.Artic. Proe
convene and turned
outward
The Twelfth Dorsal has the same general characters as the eleventh ; but may
be distinguished from it by the inferior articular processes being convex and
turned outwards, like those of the lumbar vertebra? ; by the general form of the
body, lamime, and spinous process, approaching to that of the lumbar vertebrae;
and by the transverse processes being shorter, and the tubercles at their extremi-
ties more marked.
LUMBAR VERTEBRA. 4T
Characters of the Lumbar Vertebra.
The Lumbar Vertebrae (fig. 7) are the largest segments of the vertebral column.
The body is large, broader from side to side than from before backwards, and
about equal in depth in front and 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 support of the superincum-
bent weight. The pedicles are very strong, directed backwards from the upper
Fig. 7. — A Lumbar Vertebra.
Super. Artec. Proc.
part of the bodies; consequently the inferior intervertebral notches are of large
size. The laminse are short, but broad and strong ; and the • foramen triangular,
larger than in the dorsal, smaller than in the cervical region. The superior articular
processes are concave, and look almost directly inwards; the inferior, convex, look
outwards and a little forwards ; the former are separated by a much wider interval
than the latter, embracing the lower articulating processes of the vertebra above.
The transverse processes are long, slender, directed transversely outwards in the
upper three lumbar vertebras, slanting a little upwards in the lower two. By
some anatomists they are considered homologous with the ribs. Of the two tuber-
cles noticed in connection with the transverse processes in the dorsal region, the
superior ones become connected in this region with the back part of the superior
articular processes, the inferior ones with the posterior part of the base of the
transverse processes. Although in man they are comparatively small, in some
animals they attain considerable size, and serve to lock the vertebrae more closely
together. The spinous processes are thick and broad, somewhat quadrilateral,
horizontal in direction, thicker below than above, and terminate by a rough
uneven border.
The Fifth Lumbar vertebra is characterized by having the body much thicker
in front than behind, which accounts for 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.
Structure and Development of the Vertebrae.
The structure of a vertebra differs in different parts. The body is composed
of light spongy cancellous tissue, having a thin coating of compact tissue on its
external surface perforated by numerous orifices, some of large size, for the passage
48
OSTEOLOGY.
of vessels, its interior being traversed by one or two large canals for the reception
of veins, which converge towards a single large irregular aperture or several small
ones at the posterior part of the body
Fig. 8. — Development of a Vertebra.
By o primary eertfret
plY t for Body (i$ zivcA)
J for each Lamina (6*- uteJj
Pijf. 9.
J}y 4 Secnn.dt.vr u Centres
1 for each
Traiin.Proo.
ft v»
2 tomttimes / J for Spin.proc (I6y r*j
Fitf. 10.
1 far upper su rfat
of body
1for u it dor »urfae*\
of body
II
Fie. 11.— Atlas.
12.— Axis.
f for anter. area (1''yr)
/ for eeuth )lj. ; . .»
— ,J , I before Om-tn
lateral, mats) J
Fig. 13. — Lumbar Vertebra.
2 additional ce-nt ret
Zfor odontoid proe f6r*> mo J
//or ear A lateral mass I ^
mo.)
\3?
for tubercles on Sup.
of each bone. The arch and processes
projecting from it have, on the con-
trary, an exceedingly thick covering
of compact tissue.
Development. Each vertebra is form-
ed of three primary cartilaginous por-
tions (fig. 8); one for each lamina and
its processes, and one for the body.
Ossification commences in the laminae
about the sixth week of foetal life, in
the situation where the transverse pro-
cesses afterwards project, the ossific
granules shooting backwards to the
spine, forwards to the body, and out-
wards into the transverse and articular
processes. Ossification in the body
makes its appearance in the middle of
the cartilage about the eighth week.
At birth, these three pieces are per-
fectly separate. During the first year,
the laminae become united behind, by
a portion of cartilage in which the
spinous process is ultimately formed,
and thus the arch is completed. About
the third year, the body is joined to
the arch on each side, in such a man-
ner that the body is formed from the
three original centres of ossification,
the amount contributed by the pedicles
increasing in extent from below up-
wards. Thus the bodies of the sacral
vertebrae are formed almost entirely
from the central nuclei, the bodies of
the lumbar segments are formed late-
rally and behind by the pedicles. In
the dorsal region the pedicles advance
as far forwards as the articular depres-
sions for the heads of the ribs, forming
these cavities of reception ; and in the
neck the whole of the lateral portions
of the bodies are formed by the ad-
vance of the pedicles. Before puberty,
no other changes occur excepting a
gradual increase in the growth of these
primary centres, the upper and under
surface of the bodies, and the ends of
the transverse and spinous processes,
being tipped with cartilage, in which
ossific granules are not as yet depo-
sited. At sixteen years (fig. 9), four
secondary centres appear, one for the
tip of each transverse process, and two
(sometimes united into one) for the end
of the spinous process. At twenty-
DEVELOPMENT OF THE VERTEBRAE. 49
one years (fig. 10), a thin circular plate of bone is formed in the thin layer of carti-
lage situated on the upper and under surface of the body, the former being the
thicker of the two. All these become joined ; and the bone is completely formed
about the thirtieth year of life.
Exceptions to this mode of development occur in the first, second, and seventh
cervical, and in the vertebrae of the lumbar region.
The Atlas (fig. 11) is developed by two primary centres, and by one or more
epiphyses. The two primary centres consist of the two lateral of neural masses,
ossification of which commences before birth, near the articular processes, and
extending backwards, they are separated from one another behind, at birth, by a
narrow interval filled in with cartilage. Between the second and third years,
they unite either directly or through the medium of an epiphysal centre, developed
in the cartilage near their point of junction. The anterior arch, at birth, is alto-
gether cartilaginous, and this portion of the atlas is completed by the gradual
extension forwards and ultimate junction of the two neural processes. Occasion-
ally a separate nucleus is developed in the anterior arch, which, extending laterally,
joins the neural processes in front of the pedicles ; or, there are two nuclei deve-
loped in the anterior arch, one on either side of the median line; they join to form
a single mass, which is afterwards united to the lateral portions in front of the
articulating processes.
The Axis (fig. 12) is developed by six centres. The body and arch of this bone
are formed in the same manner as the corresponding parts in the other vertebras :
one centre for the lower part of the body, and one for each lamina. The odontoid
process, which is really the centrum or body of the axis, consists originally of an
extension upwards 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-shaped 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, sometimes by a separate
epiphysal nucleus. Finally, as Mr. Humphry has lately demonstrated, the apex
of the odontoid process has a separate nucleus.
The 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 fcetal life, and joins the body and posterior division of the trans-
verse process between the fifth and sixth years. Sometimes this process continues
as a separate piece, and becoming lengthened outwards constitutes what is known
as a cervical rib.
The Lumbar Vertebrse (fig. 13) have two additional centres (besides those peculiar
to the vertebras generally), for the tubercles, which project from the back part of
the superior articular processes. The transverse process of the first lumbar is
sometimes developed as a separate piece, which may remain permanently uncon-
nected with the remaining portion of the bone ; thus forming a lumbar rib, a
peculiarity which is sometimes, though rarely, met with.
Progress of Ossification in the Spine generally. Ossification of the laminas
of the vertebras commences at the upper part of the spine, and proceeds gradually
downwards; heDce the frequent occurrence of spina bifida in the lower part of
the spinal column. Ossification of the bodies, on the other hand, commences a
little below the centre of the spinal column, about the ninth or tenth dorsal
vertebra, and extends both upwards and downwards. Although, however, the
ossific nuclei make their first appearance in the lower dorsal vertebras, the lumbar
and first sacral are those in which these nuclei are largest at birth.
Attachment of Muscles. To the Atlas are attached the Longus colli, Rectus
anticus minor, Rectus lateralis, Rectus posticus minor, Obliquus superior and
inferior, Splenitis colli, Levator anguli scapulas, Interspinous, and Intertransverse.
To the Axis are attached the Longus colli, Obliquus inferior, Rectus posticus
4
50
OSTEOLOGY.
major, Semispinals colli, Multifidus spinas, Levator anguli scapulas, Splenius colli,
Transversalis colli, Scalenus posticus, Intertransversales, Interspinales.
To the remaining Vertebras generally are attached, anteriorly, the Rectus anticus
major, Longus colli, Scalenus anticus and posticus, Psoas magnus, Psoas parvus,
Quadratus lumborum, Diaphragm, Obliquus internus and Transversalis, — poste-
riorly, the Trapezius, Latissimus dorsi, Levator anguli scapulas, Rhomboideus
major and minor, Serratus posticus superior and inferior, Splenius, Sacro-lumbalis,
Longissimus dorsi, Spinalis dorsi, Cervicalis ascendens, Transversalis colli,
Trachelo-mastoid, Complexus, Serni-spinalis dorsi and colli, Multifidus spinas,
Interspinales, Supraspinales, Intertransversales, Levatores costarum.
Saceal and Coccygeal Vertebrae.
The Sacral and Coccygeal Vertebras consist, at an early period of life, of nine
separate pieces, which are united in the adult, so as to form two bones, five
entering into the formation of the sacrum, four of the coccyx.
The Sacrum (fig. 14), so called from its having been offered in sacrifice, and
hence considered sacred, is a large triangular bone, situated at the lower part of
Fig. 14. — Sacrum: Anterior Surface.
Promontory
the vertebral column, and at the upper and back part of the pelvic cavity, where
it is inserted like a wedge between the two ossa innominata; its upper part,
or base, articulating with the last lumbar vertebra, its apex with the coccyx.
The sacrum is curved upon itself, and placed very obliquely, its upper extremity
projecting forwards, forming, with the last lumbar vertebra, a very prominent
angle, called the promontory or sacro-vertebral angle, whilst its central part is
directed backwards, so as to give increased capacity to the pelvic cavity. It
SACRUM.
51
Fig. 15. — Vertical Section of the Sacrum.
presents for examination an anterior and posterior surface, two lateral surfaces, a
base, an apex, and a central canal.
Tlie Anterior Surface is concave from above downwards, and slightly so from
side to side. In the middle are seen four transverse ridges, indicating the original
division of the bone into five separate pieces. The portions of bone intervening
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
succeeding ones diminish in size from above downwards, are flattened from before
backwards, and curved so as to accom-
modate themselves to the form of the
sacrum, being concave in front, convex
behind. At each end of the ridges, above
mentioned, are seen the anterior sacral
foramina, analogous to the intervertebral
foramina, four in number on each side,
somewhat rounded in form, diminishing
in size from above downwards, and di-
rected outwards and forwards; they
transmit the anterior branches of the
sacral nerves. External to these fora-
mina is the lateral mass, consisting, at
an early period of life, of separate seg-
ments, which correspond to the anterior
transverse processes ; these become blend-
ed, in the adult, with the bodies, with
each other, and with the posterior trans-
verse processes. Each lateral mass is
traversed by four broad shallow grooves,
which lodge the anterior sacral nerves as
they pass outwards, the grooves being
separated 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 bone (fig. 15), the bodies
are seen to be united at their circumfe-
rence 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.
The Posterior Surface (fig. 16) is convex, and much narrower than the anterior.
In the middle line, are three or four tubercles, which represent the rudimentary
spinous processes of the sacral vertebrae. 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, which diminishes in size from above
downwards; the fourth usually, and the fifth always, remaining undeveloped. Ex-
ternal to the spinous processes on each side are the laminse, broad and well marked
in the three first pieces; sometimes the fourth, and generally the fifth, being un-
developed ; in this situation the lower end of the sacral canal is exposed. External
to the laminae is a linear series of indistinct tubercles representing the articular
processes; 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 side of the sacral canal : they are called the sacral cornua, and articulate
with the cornua of the coccyx. External to the articular processes are the four
52
OSTEOLOGY.
posterior sacral foramina ; 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 the posterior sacral foramina is a series of tubercles, the rudimentary
Fig. 16. — Sacrum: Posterior Surface.
posterior transverse processes of the sacral vertebra?. The first pair of transverse
tubercles are of large size, very distinct, and correspond with each superior angle
of the bone ; the second, small in size, enter into the formation of the sacro-iliac
articulation ; the third give attachment to the oblique sacro-iliac ligaments ; and
the fourth and fifth to the great sacro-ischiatic 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 Erector spina?.
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 or ear-shaped surface, and in the fresh
state is coated with cartilage. It is bounded posteriorly by deep and uneven
impressions, for the attachment of the posterior sacro-iliac ligaments. The lower
half is thin and sharp, and gives attachment to the greater and lesser sacro-ischiatic
ligaments, and to some fibres of the Gluteus maximus; below, it presents a deep
notch, which is converted into a foramen by articulation with the transverse
process of the upper piece of the coccyx, and transmits the anterior branch of the
fifth sacral nerve.
The Base of the sacrum, which is broad and expanded, is directed upwards and
forwards. In the middle is seen an oval articular surface, which corresponds with
the under surface of the body of the last lumbar vertebra, bounded behind by
the large triangular orifice of the sacral canal. This orifice is formed behind by
the spinous process and laminae of the first sacral vertebra, whilst projecting from
DEVELOPMENT OF SACRUM.
53
Fig. 17. — Development of Sacrum.
Formed ly union, of £ Verteb ra.
2 characteristic points.
2 Additional centres
far the first 3 pieces *
at birth
it on each side are the superior articular processes; they are oval, concave,
directed backwards and inwards, like the superior articular processes of a lumbar
vertebra; in front of each articular process is an intervertebral notch, which
forms the lower half of the last intervertebral foramen. Lastly, on each side of
the articular surface is a broad and flat triangular surface of bone, which extends
outwards, and is continuous on each side with the iliac fossa.
The Apex, directed downwards and forwards, presents a small oval concave
surface for articulation with the coccyx.
The Sacral Canal runs throughout the greater part of the bone ; it is large
and triangular in form above, small and flattened from before backwards below.
In this situation its posterior wall is incomplete, from the non-development of the
lamina? and spinous processes. 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 exter-
nally by a thin layer of compact tissue.
Differences in the Sacrum of
the Male and Female. The sacrum
in the female is usually wider than in
the male; and it is much less curved,
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
backwards; which increases the size of
the pelvic cavity, and forms a more pro-
minent sacro-vertebral angle. 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. Occa-
sionally, 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 develop-
ment of the laminae and spinous pro-
cesses. The sacrum, also, varies con-
siderably 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 towards its middle. In
Fig. 18.
at 4J y'rs
Fig. 19.
. nr tJl
at 2o r-. y.
54
OSTEOLOGY.
a third set, the degree of curvature was less marked, and affected especially the
lower third of the bone.
Development (fig. 17). The sacrum, formed by the union of five vertebra?, has
thirty-five centres of ossification.
The bodies of the sacral vertebra? have each three ossific centres ; one for the
central part, and one for the epiphysal plates on its upper and under surface.
The laminse of the sacral vertebra? are each developed by two centres ; these
meet behind to form the arch, and subsequently join the body.
The lateral masses have six additional centres, two for each of the first three
vertebra?. These centres make their appearance above and to the outer side of
the anterior sacral foramina (fig. 17), and are developed into separate segments,
which correspond with the anterior transverse processes (fig. 18); they are subse-
quently blended with each other, and with the bodies and the posterior transverse
processes, to form the lateral mass.
Lastly, each lateral surface of the sacrum is developed by two epiphysal plates
(fig. 19); one for the articular surface, and one for the remaining part of the thin
lateral edge of the bone.
Period of Development. At about the eighth or ninth week of foetal life, ossifi-
cation of the central part of the bodies of the first three vertebra? commences ;
and, at a somewhat later period, that of the last two. Between the sixth and
eighth months, ossification of the lamina? takes place : and, at about the same
period, the characteristic osseous tubercles for the three first sacral vertebra? make
their appearance. The lamina? join to form the arch, and are united to the bodies,
first, in the lowest vertebra?. This occurs about the second year, the uppermost
segment appearing as a single piece about the fifth or sixth year. About the six-
teenth year, the epiphyses for the upper and under surfaces of the bodies are
formed : and, between the eighteenth and twentieth years, those for each lateral
surface of the sacrum make their appearance. At about this period, the last
two segments are joined to one another; and this pro-
cess gradually extending upwards, all the pieces
become united, and the bone completely formed from
the twenty-fifth to the thirtieth year of life.
Articulations. With four bones; the last lumbar
vertebra, coccyx, and the two ossa innominata.
Attachment of Muscles. The Pyriformis and
Coccygeus on either side ; behind, the Gluteus maxi-
mus, and Erector spina?.
The Coccyx.
The Coccyx (x6xxv%, cuckoo), so called from resem-
bling a cuckoo's beak (fig. 20), is usually formed
of four small segments of bone, the most rudi-
mentary parts of the vertebral column. In each
of the first three segments may be traced a rudi-
mentary body, articular and transverse processes;
the last 'piece (sometimes the third) being merely
a rudimentary nodule of bone, without distinct
processes. All the segments are destitute of lami-
na? and spinous processes; and, consequently, of
spinal canal, and intervertebral foramina. The first
segment is the largest, resembles the loAvermost
sacral vertebra, and often exists as a separate piece ;
the last three, diminishing in size from above down-
wards, 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, articulating by its base with the end of the
Fig. 20.— Coccyx.
Cornva
jlnterior Surfars
JPotterior S-u-rfca
THE SPINE. 55
sacrum. It presents for examination an anterior and posterior surface, two borders,
a base, and an apex. 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-coecygeal ligament,(the Levator ani muscle,
and supports the lower end of the rectum. The posterior surface is convex,
marked by transverse grooves similar to those on the anterior surface; and presents
on each side a linear row of tubercles, the rudimentary articular processes of the
coccygeal vertebra. Of these, the superior pair are very large ; and are called
the cornua of the coccyx; they project upwards, and articulate with the cornua of
the sacrum, the junction between these two bones completing the fifth sacral
foramen for the transmission of the posterior branch of the fifth sacral nerve.
The lateral borders are thin, and present a series of small eminences, which re-
present the transverse processes of the coccygeal vertebrae. Of these, the first on
each side is of large size, flattened from before backwards ; and often ascends to
join the lower part of the thin lateral edge of the sacrum, thus completing the
fifth sacral foramen : the others diminish in size from above downwards, and are
often wanting. The borders of the coccyx are narrow, and give attachment on
each side to the sacro-sciatic ligaments and Coccygeus muscle. The base presents
an oval surface for articulation with the sacrum. 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, at birth; in the second piece, at from five to ten years;
in the third, from ten to fifteen years ; in the fourth, from fifteen to twenty years.
As age advances, these various segments become united in the following order :
the first two pieces join; then the third and fourth; and, lastly, the bone is com-
pleted by the union of the second and third. At a late period of life, especially
in females, the coccyx becomes joined to the end of the sacrum.
Articulation. With the sacrum.
Attachment of Muscles. On either side, the Coccygeus; behind, the Gluteus
maxim us ; at its apex, the Sphincter ani ; and in front, the Levator ani.
Of the Spine in general.
The spinal column, formed by the junction of the vertebras, is situated in the
median line, at the posterior part of the trunk : its average length is about two
feet two or three inches; the lumbar region contributing seven parts of that
length, the dorsal eleven, and the cervical five.
Viewed in front, it presents two pyramids joined together at their bases, the
upper one being formed by all the vertebrae from the second cervical to the last
lumbar ; the lower one by the sacrum, and coccyx. Viewed somewhat more closely,
the uppermost pyramid is seen to be formed of three smaller pyramids. Of these,
the most superior one consists of the six lower cervical vertebrae; its apex being
formed by the axis or second cervical ; its base, by the first dorsal. The second
pyramid, which is inverted, is formed by the four upper dorsal vertebrae, the base
being at the first dorsal, the smaller end at the fourth. The third pyramid com-
mences at the fourth dorsal, and gradually increases in size to the fifth lumbar.
Viewed laterally (fig. 21), the spinal column presents several curves, which
correspond to the different regions of the column, and are called cervical, dorsal,
lumbar, and pelvic. The cervical curve commences at the apex of the odontoid
process, and terminates at the middle of the second dorsal vertebra ; it is convex
in front, but the least marked of all the curves. The dorsal curvature, which is
concave forwards, commences at the middle of the second, and terminates at the
middle of the twelfth dorsal. Its most prominent point behind corresponds to
the body of the seventh or eighth vertebra. The lumbar curve commences at the
middle of the last dorsal, and terminates at the sacro-.vertebral angle. It is convex
56
OSTEOLOGY.
Fig. 21. — Lateral View of Spine.
lsl Cervical
orAtlat.
6-\
IV Dorsal.
%A
/?
1? Lumbar.^r^,
u-
^mm
anteriorly; the convexity of the lower
three vertebrae being much greater than
that of the upper ones. The 'pelvic curve
commences at the sacro- vertebral articula-
tion, and terminates at the point of the
coccyx. It is concave posteriorly. These
curves are partly due to the shape of the
bodies of the vertebrae, and partly to the
intervertebral substances, as will be ex-
plained in the Articulations of the Spine.
The spine has also a slight lateral
curvature, the convexity of which is di-
rected toward the right side. This is
most probably produced, as Bichat first
explained, from the effect of muscular
action; most persons using 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, it has been
found, by Beclard, that in one or two in-
dividuals who were left-handed, the lateral
curvature was directed to the left side.
The spinal column presents for exami-
nation an anterior, a posterior, and two
lateral surfaces; a base, summit, and ver-
tebral canal.
The anterior 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 dorsal, and broadest
in the lumbar region. The whole of this
surface is convex transversely, concave from
above downwards in the dorsal region, and
convex in the same direction in the cervical
and lumbar regions.
The posterior surface presents in the
median line the spinous processes. These
are short, horizontal, with bifid extremi-
ties in the cervical region. In the dorsal
region, they are directed obliquely above,
assume almost a vertical direction in the
middle, and are horizontal, like the spines
of the lumbar vertebras, below. They
are separated by considerable intervals in
the loins, by narrower intervals in the
neck, and are closely approximated in
the middle of the dorsal region. Oc-
casionally one of these processes deviates
a little from the median line, a fact to
be remembered, as irregularities of this
sort are attendant on fractures or dis-
placements of the spine. On either side of
the spinous processes, extending the whole
length of the column, is the vertebral
groove, formed by the laminaa in the cer-
THE SKULL. 5T
vical and lumbar regions, where it is shallow, and by the laminrc and transverse
processes in the dorsal region, where it is deep and broad. In the recent state,
these grooves lodge the deep muscles of the back. External to the vertebral
grooves are the articular processes, and still more externally the transverse pro-
cesses. In the dorsal region, the latter processes stand backwards, on a place con-
siderably posterior to the same processes in the cervical and lumbar regions. In
the cervical region, the transverse processes are placed in front of the articular
processes, and between the intervertebral foramina. In the lumbar, they are placed
also in front of the articular process, but behind the intervertebral foramina. In
the dorsal region, they are posterior both to the articular processes and foramina.
The lateral surfaces are separated from the posterior by the articular processes
in the cervical and lumbar regions, and by the transverse processes in the dorsal.
These surfaces present in front the sides of the bodies of the vertebras, marked in
the dorsal region by the facets for articulation with the heads of the ribs. More
posteriorly are the intervertebral foramina, formed by the juxtaposition of the inter-
vertebral notches, oval in shape, smallest in the cervical and upper part of the dorsal
regions, and gradually increasing in size to the last lumbar. They are situated
between the transverse processes in the neck, and in front of them in the back and
loins, and transmit the spinal nerves. The base of the vertebral column is formed
by the under surface of the body of the fifth lumbar vertebra; and the summit by
the upper surface of the atlas. The vertebral 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 narrow and rounded in the back, where motion is more limited.
THE SKULL.
The Skull, or superior expansion of the vertebral column, is composed of four
vertebras, the elementary parts of which are specially modified in form and size,
and almost immovably connected, for the reception of the brain, and special
organs of the senses. These vertebras are the occipital, parietal, frontal, and nasal.
Descriptive anatomists, however, divide the skull into two parts, the Cranium and
the Face. The Cranium (xponos, 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 lachry-
mal, two malar, two palate, two inferior turbinated, vomer, inferior maxillary. The
ossicula auditus, the teeth, and Wormian bones, are not included in this enumeration.
Occipital.
Two Parietal.
Cranium, 8 bones. ) zJon ~" ,
Two Temporal.
Sphenoid.
Ethmoid.
Skull, 22 bones. ( / Two Nasal.
Face, 14 bones.
Two Superior Maxillary.
Two Lachrymal.
Two Malar.
Two Palate.
Two Inferior Turbinated.
Vomer.
Inferior Maxillary.
BONES OF THE CRANIUM.
The Occipital Bone.
The Occipital Bone (fig. 22) is situated at the back part and base of the cranium,
is trapezoid in form, curved upon itself, and presents for examination two sur-
faces, four borders, and four angles.
58
OSTEOLOGY.
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
external occipital protuberance, for the attachment of the Ligamentum nuchas; and
descending from it, as far as the foramen, a vertical ridge, the external occipital
crest. This tubercle and crest vary in prominence in different skulls. Passing
outwards from the occipital protuberance on each side are two semicircular ridges,
the superior curved lines ; and running parallel with these from the middle of the
crest, are the two inferior curved lines. The surface of the bone above the supe-
rior curved lines is smooth on each side, and in the recent state is covered by the
Occipito-frontalis muscle, whilst the ridges, as well as the surface of the bone
between them, serve for the attachment of numerous muscles. The superior
22.— Occipital Bone. Outer Surface.
t>f Hiarynx
curved line gives attachment internally to the Trapezius, externally to the Occi-
pito-frontalis, and Sterno-cleido-mastoid, to the extent shown in the figure. The
depressions between the curved lines to the Complexus internally, the Splenius
capitis and Obliquus superior externally. The inferior curved line, and the
depressions below it, afford insertion to the Rectus capitis posticus, major and minor.
The foramen magnum is a large oval aperture, its long diameter extending
from before backwards. It transmits the spinal cord and its membranes, the
spinal accessory nerves, and the vertebral arteries. Its back part is wide for the
transmission of the cord, and the corresponding margin rough for the attachment
of the dura mater inclosing it ; the forepart is narrower, being encroached upon
by the condyles ; it has projecting towards it from below the odontoid process,
and its margins are smooth and bevelled internally to support the medulla
oblongata. On each side of the foramen magnum are the condyles for articulation
with the atlas; they are convex, oblong or reniform in shape, and directed down-
wards and outwards; they converge in front, and encroach slightly upon the
anterior segment of the foramen. On the inner border of each condvle is a rough
OCCIPITAL BONE.
59
tubercle for the attachment of the ligaments (check) which connect this bone with
the odontoid process of the axis ; whilst external to them is a rough tubercular
prominence, the transverse or jugular process (the representative of the trans-
verse process of a vertebra), channelled in front by a deep notch, which forms
part of the jugular foramen. The under surface of this process affords attach-
ment to the Rectus capitis lateralis ; its upper or cerebral surface presents a deep
groove, which lodges part of the lateral sinus, whilst its prominent extremity is
marked by a quadrilateral rough surface, 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 forepart, is a foramen, the
anterior condyloid ; it is directed downwards, outwards, and forwards, and trans-
mits the hypoglossal nerve. This foramen is sometimes double. Behind each
condyle is a fossa,' perforated at the bottom by a foramen, the posterior condyloid,
for the transmission of a vein to the lateral sinus. In front of the foramen
magnum is a strong quadrilateral plate of bone, the basilar process, wider behind
than in front ; its under surface, which is rough, presenting in the median line a
tubercular ridge, the pharyngeal spine, for the attachment of the tendinous raphe
and Superior constrictor of the pharynx ; and on each side of it are rough depressions
for the attachment of the Rectus capitis anticus major, and Rectus capitis minor.
Fig. 23. — Occipital Bone : Inner Surface.
Su/ieri'or Angle
• ''Of,
Inferior Ant/lp V«
The Internal or Cerebral Surface (fig. 23) is deeply concave. The posterior
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.
60 OSTEOLOGY.
or occipital part is divided by a crucial ridge into four fossae. The two superior,
the smaller, receive the posterior lobes of the cerebrum, and present slight emi-
nences and depressions corresponding to their convolutions. The two inferior,
which receive the lateral lobes of the cerebellum, are larger than the former, and
comparatively smooth ; both are marked by slight grooves for the lodgment of
arteries. At the point of meeting of the four divisions of the crucial ridge is an
eminence, the internal occipital protuberance. It nearly corresponds to that on
the outer surface, and is perforated by one or more large vascular foramina.
From this eminence, the superior division of the crucial ridge runs upwards to
the superior angle of the bone ; it presents occasionally a deep groove for the
superior longitudinal sinus, the margins of which give attachment to the falx
cerebri. The inferior division, the internal occipital crest, 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 for the attachment of the falx cere-
belli. The transverse grooves pass outwards to the lateral angles; they are
deeply channelled, for the lodgment of the lateral sinuses, their prominent margins
affording attachment to the tentorium cerebelli.1 At the point of meeting of these
grooves is a depression, the " Torcular Herophili,"* placed a little to one or the
other side of the internal occipital protuberance. More anteriorly is the foramen
magnum, and on each side of it, but nearer its anterior than its posterior part,
the internal openings of the anterior condyloid foramina ; the internal openings
of the posterior condyloid foramina being a little external and posterior to them,
protected by a small arch of bone. In front of the foramen magnum is the basilar
process, presenting a shallow depression, the basilar groove, which slopes from
behind, upwards and forwards, and supports the medulla oblongata ; 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, which lodges
the inferior petrosal sinus.
Angles. 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. 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. The lateral angles correspond
to the outer ends of the transverse grooves, and are received into the interval
between the posterior inferior angles of the parietal and the mastoid portion of
the temporal.
Borders. The superior 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. The inferior border extends from the lateral to
the inferior angle ; its upper half is rough, and articulates with the mastoid por-
tion of the temporal, forming the masto-occipital suture : the inferior half articu-
lates 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 foramen lacerum posterius. This notch is
occasionally subdivided into two parts by a small process of bone, and presents an
aperture at its upper part, the internal opening of the posterior condyloid foramen.
Structure. The occipital bone consists of two compact laminae, called the outer
and inner tables, having between them the diploic tissue ; this bone is especially
' Usually one of the transverse grooves is deeper and broader than the other ; this seems in
nearly equal proportion on the two sides; 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, and occupies the corre-
sponding side of the median line.
2 The columns of blood coming in different directions were supposed to be pressed together at
this point.
OCCIPITAL BONE.
61
JJt/ 4- centres
at lirfJL
the 1, pit res
*cj>a rale
thick, at the ridges, protuberances, condyles, and anterior part of the basilar
process; whilst at the bottom of the fossae, especially the inferior, it is thin, semi-
transparent, and destitute of diploe.
Development (fig. 24). The occipital bone has four centres of development ;
one for the posterior or occi-
pital part, Which is formed in F'S- 24. -Development of Occipital Boue.
membrane ; one for the basilar
portion; and one for each
condyloid portion, which are
formed in cartilage.
The centre for the occipi-
tal portion appears about the
tenth week of foetal life ; and
consists, according to Blandin
and Cruveilhier, of a small
oblong plate which appears
in the situation of the occi-
pital protuberance.1 The
condyloid portions then
ossify, and lastly the basilar
portion. At birth, the bone
consists of four parts, separate from one another, the occipital portion being fissured
in the direction above indicated. At about the fourth year, the occipital 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 the superior curved line are attached the Occipito-
frontalis, Trapezius, and Sterno-cleido-mastoid. To the space between the curved
lines, the Complexus, Splenius capitis, and Obliquus superior; to the inferior
curved line, and the space between it and the foramen magnum, the Kectus
posticus major and minor ; to the transverse process, the Rectus lateralis ; and to
the basilar process, the Recti antici majores and minores, and Superior Constrictor
of the pharynx.
/ for occipital
portion
I for each condyloid
portion
or otLthlar portion
The Parietal Boxes.
The Parietal Bones {paries, a wall) form by their union the sides and roof of
the skull ; each bone is of an irregular quadrilateral form, and presents for ex-
amination two surfaces, four borders and four angles.
Surfaces. The external surface (fig. 25) is convex, smooth, and marked about
its centre by an eminence, called the parietal eminence, which indicates the point
where ossification commenced. Crossing the centre of the bone in an arched
direction is a curved ridge, the temporal ridge, for the attachment of the temporal
fascia. Above this ridge, the surface of the bone is rough and porous, and covered
by the aponeurosis of the Occipito-frontalis.; below it the bone is smooth, forms
part of the temporal fossa, and affords attachment to the Temporal muscle. At
the back part of the superior border, close to the sagittal suture, is a small
foramen, the parietal foramen, which transmits a vein to the superior longitudinal
sinus. Its existence is not constant, and its size varies considerably.
The internal surface (fig. 26), concave, presents eminences and depressions for
lodging the convolutions of the cerebrum, and numerous furrows for the ramifica-
tions of the meningeal arteries ; the latter run upwards and backwards from the
1 BGclard considers this segment to have four centres of ossification, arranged in pairs, two
above, and two below the curved lines, and Meckel describes eight, four of which correspond in
situation with those above described : of the other four, two are placed in juxta-position, at the
upper angle of the bone, and the remaining two, one at each side, in the lateral angles.
62
OSTEOLOGY.
anterior inferior angle, and from the central and posterior part of the lower
border of the bone. Along the upper margin is part of a shallow groove, which,
when joined to the opposite parietal, forms a channel for the superior longitudinal
sinus, the elevated edges of which afford attachment to the falx cerebri. Near
the groove are seen several depressions; they lodge the Pacchionian bodies.
The internal opening of the parietal foramen is also seen when that aperture
exists.
Fig. 25. — Left Parietal Bone : External Surface.
• ..T(tt,cs <wilh ot,„„
Borders. The superior, the longest and thickest, is dentated to articulate with
its fellow of the opposite side, forming the sagittal suture. The inferior 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 squamous portion of the temporal ; the posterior
portion being thick and serrated for articulation with the mastoid portion of the
temporal. The anterior border, 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. The posterior border, deeply denticulated, articulates
with the occipital, forming the lambdoid suture.
Angles. The anterior superior, thin and pointed, corresponds with that portion
of the skull which in the foetus is membranous, and is called the anterior fon-
tanels. The anterior inferior 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. The posterior superior 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 fontanelle. The ptosterior inferior
PARIETAL BONE
63
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-
owe centre, which corresponds with the parietal eminence, and makes its first
appearance about the fifth or sixth week of foetal life. Ossification gradually
Fig. 26. — Left Parietal Bone : Internal Surface.
J Amjle
Toitl.IiiJiir.Aui
Ant. Infer. Avqle
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.
Articulations. With five bones; the opposite parietal, the occipital, frontal,
temporal, and sphenoid.
Attachment of Muscles. To one only, the Temporal.
The Frontal Bone.
This bone, which resembles a cockle-shell in form, consists of two portions — .
a vertical or frontal portion, situated at the anterior part of the cranium, forming
the forehead ; and a horizontal or orbito-nasal portion, which enters into the forma-
tion of the roof of the orbits and nose.
Vertical Portion. External Surface (fig. 27). In the median line, traversing
the bone from the upper to its lower part, is occasionally seen a slightly elevated
ridge, and in young subjects a suture, which represents the point of union of the
two lateral halves of which the bone consists at an early period of life ; in the
adult, this suture usually disappears, excepting below. On either side of this
ridge, a little below the centre of the bone, is a rounded eminence, the frontal
eminence. These eminences vary in size in different individuals, and are occa-
sionally unsymmetrical in the same subject. They are especially prominent iix
64
OSTEOLOGY.
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 groove, is
the superciliary ridge, broad internally where it is continuous with the nasal
eminence, but less distinct as it arches outwards. These ridges are caused by the
projection outwards of the frontal sinuses. Beneath the superciliary ridge is the
supra-orbital arch, 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 inner third of this arch is a notch, sometimes converted into
Fig. 27. — Frontal Bone : Outer Surface.
Exlernal
Angular hrot.
Natal
a foramen by a bony process or ligament, and called the supra-orbital notch or
foramen. It transmits the supra-orbital artery, veins, and nerve. A small
aperture is seen in the upper part of the notch, which transmits a vein from the
diploe to join the ophthalmic vein. The supra-orbital arch terminates externally
in the external angular process, and internally in the interal angular process.
The external angular process is strong, prominent, and articulates with the malar
bone : running upwards and backwards from it is a sharp curved crest, the tem-
poral ridge, for the attachment of the temporal fascia; and beneath it 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 two is a rough,
uneven interval, the nasal notch, which articulates in the middle line with the
nasal, and on either side with the nasal process of the superior maxillary bone.
The notch is continuous below, with a long pointed process, the nasal spine.
FRONTAL BONE.
G5
Vertical Portion. Internal Surface (fig. 28). Along the middle line is a vertical
groove, the edges of which unite below to form a ridge, the frontal crest ; the
groove lodges the superior longitudinal sinus, whilst its edges afford attachment
to the falx cerebri. The crest terminates below at a small opening, the foramen
csecum, which is generally completed behind the ethmoid. This foramen varies
in size in different subjects, is usually partially, or completely, impervious, lodges
a process of the falx cerebri, 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 eminences and depressions for the
convolutions of the brain, and numerous small furrows for lodging the ramifica-
tions of the anterior meningeal arteries. Several small, irregular fossae are also
seen on either side of the groove, for the reception of the Pacchionian bodies.
Fig. 28. — Frontal Bone. Inner Surface.
1
with Sup. Max
with Na
with PcrpeniLeular ylatc cf Ethmoid
Frontal j&'inus
Earpa ndtd base of JVhural Spnie,
Jnrnuriij part <>f Roirf ef /yose
Horizontal Portion; external Surface. This portion of the bone consists of
two thin plates, which form the vault of the orbits, separated from one another by
the ethmoidal notch. Each orbital vault consists of a smooth, concave, triangular
plate of bone, marked at its anterior and external part, immediately beneath the
external angular process, by a shallow depression, the lachrymal fossa, for lodging
the lachrymal gland; and at its anterior and internal part, by a depression, some-
times a small tubercle, for the attachment of the fibrous pulley of the Superior
oblique muscle. The ethmoidal notch separates the two orbital plates: it is
quadrilateral, and filled up, when the bones are united, by the cribriform 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 ethmoid, complete
the ethmoidal cells : two grooves are also seen crossing these edges transversely ;
5
66
OSTEOLOGY.
they are converted into canals by articulation with the ethmoid, and are called
the anterior and posterior ethmoidal canals; 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 is the nasal spine, a sharp-pointed eminence which projects downwards and
forwards, and articulates in front with the crest of the nasal bones ; behind, it is
marked by two grooves, separated by a vertical ridge : the ridge articulates with
the perpendicular lamella of the ethmoid, the grooves form part of the roof of the
nasal fossa?. On either side of the base of the nasal spine are the openings of the
frontal sinuses. These are two irregular cavities, which extend upwards and
outwards, a variable distance, between the two tables of the skull, and are separated
from one another by a thin bony septum. They give rise to the prominences
above the root of the nose, called the nasal eminences and superciliary ridges. In
the child they are generally absent, and they become gradually developed as age
advances. These cavities vary in size in different persons, are larger in men than
in women, and are frequently of unequal size on the two sides, the left being
commonly the larger. Occasionally they are subdivided by incomplete bony
laminae. They are lined by mucous membrane ; and communicate with the nose
by the infundibulum, and occasionally with each other by apertures in the septum.
The Internal Surface of the horizontal portion presents the convex upper
surfaces of the orbital plates, separated from each other in the middle line by the
ethmoidal notch, and marked by eminences, and depressions for the convolutions
of the anterior lobes of the brain.
Borders. 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, 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. The border of the horizontal
portion is thin, serrated, and articulates with the lesser wing of the sphenoid.
Structure. The vertical portion, and external angular processes, are very thick,
consisting of diploic tissue contained between two compact laminae. The hori-
zontal 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. 29). The frontal bone is formed in membrane, being
developed by tico centres, one for each
lateral half, which make their appearance,
at an early period of foetal life, in the situ-
ation of the orbital arches. From this
point, ossification extends, in a radiating
manner, upwards into the forehead, and
backwards over the orbit. At birth, it
consists of two pieces, which afterwards
become united along the middle line, by
a suture which runs from the vertex to
the root of the nose. This suture be-
comes obliterated within a few years after
birth ; but it occasionally remains through-
out life.
Articulations. With twelve bones : two
parietal, sphenoid, ethmoid, two nasal,
two superior maxillary, two lachrymal, and two malar.
Attachment of Muscles. To three pairs: the Corrugator supercilii, Orbicularis
palpebrarum, and Temporal.
Fig. 29.— Frontal Bone at Birth.
Developed by two lateral Halves.
TEMPORAL BONE.
GT
The Temporal Bones.
The Temporal Bones are so called because they occupy that part of the head
on which the hair first begins to turn gray, thus indicating the age. They are
situated at the side and base of the skull, and present for examination a squamous,
mastoid, and petrous portion.
The Squamous Portion {squama, a scale), the most anterior and superior part of
the bone (fig. 30), is scale-like in form, thin and translucent in texture. Its outer
surface is smooth, convex, and grooved at its back part for the deep temporal
arteries ; it affords attachment to the Temporal muscle, and forms part of the
temporal fossa. At its back part may be seen a curved ridge, part of the tem-
poral ridge ; it serves for the attachment of the temporal fascia, limits the origin
of the Temporal muscle, and marks the boundary between the squamous and
mastoid portions of the bone. Projecting from the lower part of the squamous
Fig. 30. — Left Temporal Bone. Outer Surface.
teiZfot
portion is a long arched outgrowth of bone, the zygomatic process. It is at first
directed outwards, its two surfaces looking upwards and downwards ; it then appears
as if twisted upon itself, and takes a direction forwards, its surfaces now looking
inwards and outwards. The superior border of this 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. This process is connected to the temporal bone by three divisions,
called the roots of the zygomatic process, an anterior, middle, and posterior. The
anterior, which is short, but broad and strong, runs transversely inwards into a
rounded eminence, the eminentia articularis. This eminence forms the front
boundary of the glenoid fossa, and in the recent state is covered with cartilage.
The middle root forms the outer margin of the glenoid cavity ; running obliquely
68
OSTEOLOGY.
inwards it terminates at the commencement of a well-marked fissure, the Glaserian
fissure ; whilst the posterior root, which is strongly marked, runs from the upper
border of the zygoma, in an arched direction, upwards and backwards, forming the
posterior part of the 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 ligament of the lower jaw ; and between the anterior and middle roots is
an oval depression, forming part of the glenoid fossa (y*.^, a shallow pit), for the
reception of the condyle of the lower jaw. This fossa is bounded, in front, by the
eminentia articularis ; behind, by the vaginal process ; and, externally, by the
auditory process, and middle root of the zygoma ; and is divided into two parts
by a narrow slit, the Glaserian fissure : the anterior part, formed by the squamous
portion of the bone, is smooth, and covered in the recent state with cartilage, and
articulates with the condyle of the lower jaw. This part of the glenoid fossa is
separated from the auditory process, by a small tubercle, the post- glenoid process,
Fig. 31. — Left Temporal Bone. Inner Surface.
■parietal
Aqticduetux Veshhuli.
jDepTCXsivii far DuTCr-vuitrr
Meatus Atiduonas i ttternus
"'Ln^ejor Superior Brnfimrmfar Ca,n*l
• Jliatus FaLlopii
Opcmnyfor Smaller Petrosal Mrt-c
Dcnrfsuan for Cassertan gaiujhcm
BriUlf passed thrcuyh Carotid Ctuud
the representative of a prominent tubercle which, in some of the mammalia,
descends behind the condyle of the jaw, and prevents it being displaced backwards
during mastication (Humphry). The posterior part of the glenoid fossa is formed
chiefly by the vaginal process of the petrous portion, and lodges part of the parotid
gland. The Glaserian fissure, which leads into the tympanum, lodges the pro-
cessus gracilis of the malleus, and transmits the Laxator tympani muscle and the
anterior tympanic artery. The chorda tympani nerve passes through a separate
canal parallel to the Glaserian fissure (canal of Huguier), on the outer side of the
Eustachian tube, in the retiring angle between the squamous and petrous portions
of the temporal bone.
The internal surface of the squamous portion (fig. 31) is concave, presents
numerous eminences and depressions for the convolutions of the cerebrum, and
two well-marked grooves for branches of the middle meningeal artery.
Borders. The superior border is thin, bevelled at the expense of the internal
surface, so as to overlap the lower border of the parietal bone, forming the
TEMPORAL BONE. 09
squamous suture. The anterior inferior border is thick, serrated, and hovelled
alternately at the expense of the inner and outer surfaces, for articulation with
the great wing of the sphenoid.
The Mastoid Portion (paatos, a nipple or teat) is situated at the posterior part of
the bone ; its outer surface is rough, and perforated by numerous foramina. One
of these, of large size, situated at the posterior border of the bone, is termed the
mastoid foramen; it transmits a vein to the lateral sinus and a small artery.
The position and size of this foramen arc very variable, being sometimes situated
in the occipital bone, or in the suture between the temporal and the occipital.
The mastoid portion is continued below into a conical projection, the mastoid pro-
cess, the size and form of which vary somewhat in different individuals. 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, for the attachment of the Digastric nmscle; and running
parallel with it, but more internal, the occipital groove, which lodges the occipital
artery. The internal surface of the mastoid portion presents a deeply curved
groove, which lodges part of the lateral sinus ; and into it may be seen opening
the mastoid foramen. A section of the mastoid process shows it to be hollowed
out into a number of cellular spaces, communicating with each other, called the
mastoid cells ; they open by a single or double orifice into the back of the tym-
panum ; are lined by a prolongation of its lining membrane ; and, probably, form
some secondary part of the organ of hearing. The mastoid cells, like the other
sinuses of the cranium, are not developed until after puberty ; hence the promi-
nence of this process in the adult.
Borders. The superior border of the mastoid portion is broad and rough, its
serrated edge sloping outwards, for articulation with the posterior inferior angle
of the parietal bone. The posterior border, also uneven and serrated, articulates
with the inferior border of the occipital bone between its lateral angle and jugular
process.
The Petrous Portion («irpo?, a rock), 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 forwards, inwards,
and a little downwards. It presents for examination a base, an apex, three sur-
faces, and three borders ; and contains, in its interior, the essential parts of the
organ of hearing. 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 their divergence, which brings into view the oval expanded orifice of a canal
leading into the tympanum, the meatus auditorius externus. This canal is situated
between the mastoid process and the posterior and middle roots of the zygoma ;
its upper margin is smooth and rounded, but the greater part of its circumference
is surrounded by a curved plate of bone, the auditory process, the free margin of
which is thick and rough for the attachment of the cartilage of the external ear.
The apex of the petrous portion, rough and uneven, is received into the angular
interval between the spinous process of the sphenoid, and the basilar process of
the occipital; it presents the anterior orifice of the carotid canal, and forms the
posterior and external boundary of the foramen lacerum medium.
The anterior surface of the petrous portion (fig. 31) forms the posterior
boundary of the middle fossa of the skull. This surface is continuous with the
squamous portion, to which it is united by a suture, the temporal Suture, the
remains of which are distinct at a late period of life. This surface presents six
points for examination. 1. An eminence near the centre which indicates the
situation of the superior semicircular canal. 2. On the outer side of this eminence
is a depression, indicating the position of the tympanum, the layer of bone which
separates the tympanum from the cranial cavity being extremely thin. 3. A
shallow groove, sometimes double, leading backwards to an oblique opening, the
hiatus Fallopii, for the passage of the petrosal branch of the Vidian nerve. 4.
A smaller opening, occasionally seen external to the latter for the passage of the
10
OSTEOLOGY.
smaller petrosal nerve. 5. Near the apex of the bone is seen the termination of
the carotid canal, the wall of which in this situation is deficient in front. 6. Above
this canal is a shallow depression for the reception of the Casserian ganglion.
The posterior surface forms the front boundary 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 examination. 1. About its centre is a large orifice,
the meatus auditorius internus. This aperture varies considerably in size ; its
margins are smooth and rounded; and it leads into a short canal, about four lines
in length, which runs directly outwards. The end of the canal is closed by a
vertical plate, divided by a horizontal crest into two unequal portions. It trans-
mits the auditory and facial nerves, and auditory artery. 2. Behind the meatus
auditorius is a small slit, almost hidden by a thin plate of bone, leading to a
canal, the aquoeductus vestibuli ; it transmits a small artery and vein, and lodges
a process of the dura mater. 3. In the interval between these two openings, but
Fig. 32. — Petrous Portion. Inferior Surface.
fon&MluiUufimn tab*
and Te^ar^mpani^,^^
Levator palati
Rough Quadrilateral, Su-rfa+e
°J»™y of carrtd camd
Canal/or Jaeohon, nerve
^uMacrus Corhleic
Canal far Arnold'* nerve-
Jugular fossa
Vagcnal _prace<K
Styloid praeess-
Stylo- mastoid foramen
Jugular Surface
Auricular fissure
STYLO-PHARYNGEOS
above them, is an angular depression which lodges a process of the dura mater,
and transmits a small vein into the cancellous tissue of the bone.
The inferior or basilar surface (fig. 32) 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 opening of the carotid canal, a large circular aperture, which ascends at
first vertically upwards, and then, making a bend, runs horizontally forwards and
inwards. It transmits the internal carotid artery, and the carotid plexus. 3. The
aquseductus cochleae, a small triangular opening, lying on the inner side of the
latter, close to the posterior border of the petrous portion ; it transmits a vein from
the cochlea, which joins the internal jugular. 4. Behind these openings is a deep
depression, the jugular fossa, which varies in depth and size in different skulls; it
TEMPORAL BONE.
U
lodges the internal jugular vein, and, with a similar depression on the margin of
the occipital bone, forms the foramen lacerum posterius. 5. A small foramen for
the passage of Jacobson's nerve (the tympanic branch of the glossopharyngeal).
This is seen in front of the bony ridge dividing the carotid canal from the jugular
fossa. 6. A small foramen seen on the inner wall of the jugular fossa, for the
entrance of the auricular branch of the pncumogastric (Arnold's) nerve. 7. Behind
the jugular fossa is 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, a very broad sheath-like plate of bone,
which extends from the carotid canal to the mastoid process ; it divides behind
into two laminae, receiving between them the 9th point for examination, the styloid
process ; a long sharp spine, about an inch in length, continuous with the vaginal
process, between the laminae of which it is received, and directed downwards,
forwards, and inwards. It varies in size and shape ; and sometimes consists of
several pieces united by cartilage. It affords attachment to three muscles, the
Stylo-pharyngeus, Stylo-glossus, and Stylo-hyoideus ; and two ligaments, the stylo-
hyoid, and stylo-maxillary. 10. The stylo-mastoid foramen, a rather large orifice,
placed between the styloid and mastoid processes ; it is the termination of the
aquaeductus Fallopii, and transmits the facial nerve, and stylo-mastoid artery.
11. The auricular fissure, situated between the vaginal and mastoid processes, for
the exit of the auricular branch of the pneumogastric nerve.
Borders. The superior, the longest, is grooved for the superior petrosal sinus,
and has attached to it the tentorium cerebelli : at its inner extremity is a semilunar
notch, upon which reclines the fifth nerve. The posterior border is intermediate
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 excavation,
the jugular fossa, 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. 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 these two parts, are
seen two canals, separated from one another by a thin plate of bone, the processus
cochleariformis ; they both lead into the tympanum, the upper one transmitting
the Tensor tympani muscle, the lower
one the Eustachian tube. ^h
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. 33). The tempo-
ral bone is developed by four centres,
exclusive of those for the internal ear
and the ossicula, viz.: — one for the
squamous portion including the zygo-
ma, one for the petrous and mastoid
parts, one for the styloid, and one for
the auditory process (tympanic bone).
The first traces of the development of
this bone appear in the squamous por-
tion, about the time when osseous
matter is deposited in the vertebne ;
the auditory process succeeds next;
it consists of an elliptical portion of
bone, forming about three-fourths of
a circle, the deficiency being above; it *f°* StyU&pm*.
33. — Development of Temporal Bone.
By four Centres.
1 for Squamous
portum induaiiiM ■' r^i.
Zuqomai.
g& mo.
I fjr Audctoru
jirottsa
for Petrous
8r Xo,stijid
portions
72
OSTEOLOGY.
is grooved along its concave surface for the attachment of the membrana tympani,
and becomes united by its extremities to the squamous portion during the last
months of intrauterine life. The petrous and mastoid portions then become
ossified, and^ lastly the styloid process, which remains separate a considerable
period, and is occasionally never united to the rest of the bone. At birth, the
temporal bone, excluding the styloid process, is formed of three pieces, the
squamous and zygomatic, the petrous and mastoid, and the auditory. The
auditory process joins with the squamous at about the ninth month. The petrous
and mastoid join with the squamous during the first year, and the styloid process
becomes united between the second and third years. The subsequent changes in this
bone are the extension outwards of the auditory process, so as to form the meatus
auditorius ; the glenoid fossa becomes deeper ; and the mastoid part, which at an
early period of life is quite flat, enlarges from the development of numerous
cellular cavities in its interior.
Articulations. With five bones, occipital, parietal, sphenoid, inferior maxillary
and malar.
Attachment of Muscles. To the squamous portion, the Temporal; to the z3rgoma,
the Masseter; to the mastoid portion, the Occipito-frontalis, Sterno-mastoid,
Splenius capitis, Trachelo-mastoid, Digastricus and Eetrahens aurem; to the
styloid process, the Stylo-pharyngeus, Stylo-hyoideus and Stylo-gloss us ; and to
the petrous portion, the Levator palati, Tensor tympani, and Stapedius.
The Sphenoid Bone.
The Sphenoid bone (atyijv, a wedge; ftSo?. likeness) 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 outwards on each side of the body ; and two
processes, the pterygoid processes, which project from it below.
The Body is of large size, quadrilateral in form, 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 superior surface (fig. 34). From before, backwards, is seen a prominent
spine, the ethmoidal spine, for articulation with the ethmoid ; behind this a smooth
Fig. 34. — Sphenoid Bone. Superior Surface.
maau cu^a pro*** mmddaI s M
X-o<n£,
Jlopcbwcn Optieu
Tovatiion Zacrrwm
Qnrcn'us. or Sjjtwrwi.-iairUiicrc
J'uramtm JtctotiJo.vi,-'
„ Vtfoliii
„ OuaJt,
SPHENOID BONE.
73
surface presenting, in the median line, a slight longitudinal eminence, with a
depression on each side, for lodging the olfactory nerves. A narrow transverse
groove, the optic groove, bounds the above-mentioned surface behind ; it lodges
the optic commissure, and terminates on either side in the optic foramen, for the
passage of the optic nerve and ophthalmic artery. Behind the optic groove is a
small eminence, olive-like in shape, the olivary process ; and still more posteriorly,
a deep depression, the pituitary fossa, or sella Turcica, which lodges the pituitary
body. This fossa is perforated by numerous foramina, for the transmission of
nutrient vessels to the substance of the bone. It is bounded in front by two small
eminences, one on either side, called the middle clinoid processes (xxlvr;, a bed),
and behind by a square-shaped plate of bone, terminating at each superior angle
in a tubercle, the posterior clinoid processes, the size and form of which vary
considerably in different individuals. These processes deepen the pituitary fossa,
and serve for the attachment of prolongations from the tentorium. The sides of
the plate of bone supporting the posterior clinoid processes are notched, for the
passage of the sixth pair of nerves ; and behind, it presents a shallow depression,
which slopes obliquely backwards, and is continuous with the basilar groove of
the occipital bone ; it supports the medulla oblongata. On either side of the body
is a broad groove, curved somewhat like the italic letter/; it lodges the internal
carotid artery and the cavernous sinus, and is called the cavernous groove. The
Fig. 35. — Sphenoid Bone. Anterior Surface.
posterior surface, quadrilateral in form, articulates with the basilar process of the
occipital bone. During childhood, a separation between these bones exists by
means of a layer of cartilage ; but in after-life this becomes ossified, ossification
commencing above, and extending downward, and the two bones are then im-
movably connected together. The anterior surface (fig. 35) presents, in the
middle line, a vertical lamella of bone, which articulates in front with the per-
pendicular plate of the ethmoid, forming part of the septum of the nose. On
either side of it are the irregular openings leading into the sphenoidal sinuses.
These are two large irregular cavities, hollowed out of the interior of the body
of the sphenoid bone, and separated from one another by a more or less complete
perpendicular bony septum. Their form and size vary considerably; they are
seldom symmetrical, and are often partially subdivided by irregular osseous
laminae. Occasionally they extend into the basilar process of the occipital nearly
as far as the foramen magnum. The septum is seldom quite vertical, commonly
being bent to one or the other side. These sinuses do not exist in children ; but
U OSTEOLOGY.
they increase in size as age advances. They are partially closed, in front and
below, by two thin curved plates of bone, the sphenoidal turbinated bones,
leaving a round opening at their upper parts, by which they communicate with
the upper and back part of the nose, and occasionally with the posterior ethmoidal
cells. The lateral margins of this surface present a serrated edge, which articu-
lates with the os planum of the ethmoid, completing the posterior ethmoidal cells ;
the lower margin, also rough and serrated, articulates with the orbital process of
the palate bone ; and the upper margin with the orbital plate of the frontal bone.
The inferior surface presents, in the middle line, a triangular spine, the rostrum,
which is continuous with the vertical plate on the anterior surface, and is received
into a deep fissure between the alas of the vomer. On each side may be seen a
projecting lamina of bone, which runs horizontally inwards from near the base of
the pterygoid 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,
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 Wings are two strong processes of bone, which arise at the sides
of the body, and are curved in a direction upwards, outwards, and backwards ;
being prolonged behind into a sharp-pointed extremity, the spinous jwocess of the
sphenoid. Each wing presents three surfaces and a circumference. The superior
or cerebral surface forms part of the middle fossa of the skull; it is deeply
concave, and presents 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 transmission of the second division of the fifth nerve. Behind
and external to this, is a large oval foramen, the foramen ovale, for the transmission
of the third division of the fifth, the small meningeal artery, and the small petrosal
nerve. 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.
transmitting a small vein. Lastly, in the apex of the spine of the sphenoid is a
short canal, sometimes double, the foramen spinosum ; it transmits the middle
meningeal artery. The external surface is convex, and divided by a transverse
ridge, the pterygoid ridge, into two portions. The superior or larger, convex
from above downwards, concave from before backwards, enters into the formation
of the temporal fossa, and attaches part of the Temporal muscle. The inferior
portion, smaller in size and concave, enters into the formation of the zygomatic
fossa, and affords attachment to the External pterygoid muscle. It presents, at
its posterior part, a sharp-pointed eminence of bone, the spinous process, to which
are connected the internal lateral ligament of the lower jaw, and the Laxator
tympani muscle. The pterygoid ridge, dividing the temporal and zygomatic
portions, gives attachment to part of the External pterygoid muscle. At its inner
extremity is a triangular spine of bone, which serves to increase the extent of
origin of this muscle. 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
enters into the formation of the sphenoidal fissure ; whilst externally it presents a
serrated margin, for articulation with the malar bone. At the upper part of the
inner border is a notch, for the transmission of a branch of the ophthalmic artery ;
and at its lower part a small pointed spine of bone, which serves for the attachment
of part of the lower head of the External rectus muscle. One or two small foramina
may occasionally be seen, for the passage of arteries; they are called the external
orbitar foramina. Circumference : from the body of the sphenoid to the spine,
commencing from behind, the outer half of this margin is serrated, for articula-
tion with the petrous portion of the temporal bone ; whilst the inner half forms
the anterior boundary of the foramen lacerum medium, and presents the posterior
aperture of the Vidian canal. In front of the spine, the circumference of the
SPHENOID BONE
75
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 broad 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.
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 outwards, terminate in a more or less acute point.
The superior surface of each is smooth, flat, broader internally than externally,
and supports the anterior lobe of the brain. The inferior surface forms the back
part of the roof of the orbit, and the upper boundary of the sphenoidal fissure or
foramen lacerum anterius. 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 orbital surface of the
greater wing ; and is converted into a foramen by the articulation of this bone
with the frontal. It transmits the third, fourth, ophthalmic division of the fifth and
sixth nerves, and the ophthalmic vein. The anterior border of the lesser wing is
serrated, for articulation with the frontal bone ; the posterior, smooth and rounded,
is received into the fissure of Sylvius of the brain. The inner extremity of this
border forms the anterior clinoid process. 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 the muscles of the eye.
Between the two roots is the optic foramen, for the transmission of the optic nerve
and ophthalmic artery.
The Pterygoid processes (rttipvZ, a wing, rl8oi} likeness), one on each side (fig. 36),
descend perpendicularly from
the point where the body and FiS- 36.— Sphenoid Bone. Posterior Surface,
great wing unite. Each pro-
cess consists of an external
and an internal plate, separ-
ated behind by an interven-
ing notch, the pterygoid fossa ;
but joined partially in front.
The external pterygoid plate is
broad and thin, turned a little
outwards, and forms part of
the inner wall of the zygo-
matic fossa. It gives attach-
ment, by its outer surface, to
the External pterygoid; its
inner surface forms part of
the pterygoid fossa, and gives
attachment to the Internal
pterygoid. The internal pterygoid plate is much narrower and longer, curving
outwards, at its extremity, into a hook-like process of bone, the hamular process,
around which turns the tendon of the Tensor palati muscle. At the base of this
plate is a small, oval, shallow depression, the scaphoid fossa, from which arises the
Tensor palati, and above which is seen the posterior orifice of the Vidian canal.
The outer surface of this plate forms part of the pterygoid fossa, the inner sur-
face forming the outer boundary of the posterior aperture of the nares. The
two pterygoid plates are separated below by an angular interval, in which the
pterygoid process, or tuberosity, of the palate bone is received. The anterior
surface of the pterygoid process is very broad at its base, and forms the pos-
76
OSTEOLOGY.
Fig. 37. — Plan of the Development of
Sphenoid. By Ten Centres.
/ frreaci Teste* vniiq la Ant '- '/"irr 'J body
\ lfvr-tad, inC.ptery.pl-
tfir tool great iving tr exz._ptcrygpkt.tc
lJcrruuJi Splitncidal turbinated bone
terior wall of the sphenomaxillary 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.
Development. The sphenoid bone is developed by ten centres, six for the pos-
terior sphenoidal division, and four for the anterior sphenoidal. The six centres
for the posterior sphenoidal division are, one for each greater wing and external
pterygoid plate ; one for each internal ptery-
goid plate; two for posterior part of the
body. The four for the anterior sphe-
noidal are, one for each lesser wing and
anterior part of the body; and one for
each sphenoidal turbinated bone. Ossifi-
cation takes place in these pieces in the
following order: the greater wing and ex-
ternal pterygoid plate are first formed,
ossific granules being deposited close to the
foramen rotundum on each side, at about
the second month of foetal life ; ossification
spreading outwards into the great wing,
and downwards into the external pterygoid
plate. Each internal pterygoid plate is
then formed, and becomes united to the external about the middle of foetal life.
The two centres for the posterior part of the body appear as separate nuclei, side
by side, beneath the sella Turcica ; they join about the middle of foetal life into
a single piece, which remains ununited to the rest of the bone until after birth.
Each lesser wing is formed by a separate centre, which appears on the outer side
of the optic foramen, at about the third month; they become united and join
with the body at about the eighth month of foetal life. At about the end of the
third year, ossification has made its appearance in the sphenoidal spongy bones.
At birth, the sphenoid consists of three pieces ; viz., the greater wing and
pterygoid processes on each side ; the lesser wings and body united. 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.
Articulations. The sphenoid articulates with all the bones of the cranium, and
five of the face ; the two malar, two palate, and vomer. The exact extent of articu-
lation with each bone is shown in the accompanying figures.
Attachment of Muscles. The Temporal, External pterygoid, Internal pterygoid,
Superior constrictor, Tensor palati, Laxator tympani, Levator palpebr«3, Obliquus
superior, Superior rectus, Internal rectus, Inferior rectus, External rectus.
The Sphenoidal Spongy Bones.
The Sphenoidal Spongy Bones are two thin, curved plates of bone, 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 of variable size being left in their anterior wall through
which the sphenoidal sinuses open into the nasal fossse. They are irregular in
form, and taper to a point behind, being broader and thinner in front. Their
inner surface, which looks towards the cavity of the sinus, is concave ; their outer
surface convex. Each bone articulates in front with the ethmoid, externally with
the palate ; behind, its point is placed above the vomer, and is received between
the root of the pterygoid process on the outer side, and the rostrum of the sphe-
uoid on the inner.
ETHMOID BONE.
77
The Ethmoid Bone.
The Ethmoid (^u6j, 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,
Fig. 38. — Ethmoid Bone. Outer Surface of Right Lateral
Mass (enlarged).
and contributing to form each
of these cavities. It consists
of three parts : a horizontal
plate, which forms part of the
base of the cranium ; a per-
pendicular plate, which forms
part of the septum nasi ; and
two lateral masses of cells.
The Horizontal or Cribri-
form Plate (fig. 38) 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 upwards from the
middle line of this plate, is a
thick smooth triangular pro-
cess of bone, the crista galli,
so called from its resemblance
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 cerebri. Its
anterior border, short and thick, articulates with the frontal bone, and presents
two small projecting alae, which are received into corresponding depressions in
the frontal, completing the foramen cascum behind. Its sides are smooth, and
sometimes bulging, when it is found to inclose a small sinus. On each side of
the crista galli, the cribriform plate is narrow, and deeply grooved, to support
the bulb of the olfactory nerves, and is perforated by foramina for the passage of
its filaments. These foramina 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 foramina 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 cribri-
form plate, on each side
Shown by
if.'turbiaatetl ti.
of the crista galli, is a
small fissure, which
transmits the nasal
branch of the ophthal-
mic nerve; and at its
posterior part a trian-
gular notch, which re-
ceives the ethmoidal
spine of the sphenoid.
The Perpendicular
Plate (fig. 39) 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
Fig. 39. — Perpendicular Plate of Ethmoid (enlarged),
removing the Right Lateral Mass.
vn'tA Ethmoid,
73
OSTEOLOGY.
circumference, and is generally deflected a little to one side. Its anterior border
articulates with the frontal spine and crest of the nasal bones. Its posterior,
divided into two parts, is connected by its upper half with the rostrum of the
sphenoid ; by its lower half with the vomer. The inferior border serves for the
attachment of the triangular cartilage of the nose. On each side of the perpen-
dicular plate numerous grooves and canals are seen, leading from foramina on
the cribriform plate ; they lodge filaments of the olfactory nerves.
The Lateral Masses of the ethmoid consist of a number of thin-walled cellular
cavities, the ethmoidal cells, interposed between 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. In the disarticulated bone, many of these cells
appear to be broken ; but when the bones are articulated, they are closed in in
every part. The upper surface of each lateral mass presents a number of apparently
half- broken cellular spaces ; these, however, are completely closed in when articu-
lated with the edges of the ethmoidal fissure 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 foramina, 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 turbi-
nated bones, and 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 square plate. of bone, called the os planum; 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 and orbital process of the
palate ; in front, with the lachrymal ; and behind, with the sphenoid.
From the inferior part of each lateral mass, immediately beneath the os planum,
there projects downwards and backwards an irregular lamina of bone, called
the unciform process, from its hook-like form ; it serves to close in the upper part
of the orifice of the antrum, and arti-
Fig. 40.— Ethmoid Bone. Inner Surface of Right culates with the ethmoidal process of
Lateral Mass (enlarged). ,1 • n • v • . j -i
the interior turbinated bone.
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 convo-
luted margin, the middle turbinated
bone. The whole of this surface is
rough, and marked above by numerous
grooves which run nearly vertically
downwards from the cribriform plate ;
they lodge branches of the olfactory nerve, which are distributed 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, bounded above by a thin
curved plate of bone — the superior turbinated bone. By means of an orifice at
the upper part of this fissure, the posterior ethmoidal cells open into the nose.
Below and in front of the superior meatus is seen the convex surface of another
thin convoluted plate of bone— the middle turbinated bone. It extends along the
whole length of the inner surface of each lateral mass; its lowermargin is free
and thick, and its concavity, directed outwards, assists in forming the middle
meatus. It is by means of a large orifice at the upper and front part of the
middle meatus, that the anterior ethmoid cells, and through them the frontal sinuses,
by means of a funnel-shaped canal, the infundibulum, communicate with the nose.
The cellular cavities of each lateral mass, thus walled in by the os planum on
the outer side, and by its articulation with the other bones already mentioned, are
THE FONTANELLES.
t9
divided by a thin transverse bony partition into two sets, which do not commu-
nicate with each other; they are termed the anterior and posterior "ethmoidal cells;
the former, the smallest but the most numerous, communicate with the frontal
sinuses above, and the middle meatus below, by means of a long flexuous cellular
canal, the infundibulum ; the posterior, the largest and least numerous, open into
the superior meatus, and communicate (occasionally) with the sphenoidal sinuses.
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 first
appearance in the os planum between the fourth and fifth months of foetal life,
and afterwards in the spongy bones. At birth, the bone consists of the two
lateral masses, which are small and ill-developed; but when the perpendicular
and horizontal plates begin to ossify, as they do about the first year after birth,
the lateral masses become joined to the cribriform plate. The formation and
increase in the ethmoidal cells, which complete the formation of the bone, take
place about the fifth or sixth year.
Articulations. "With fifteen bones; the sphenoid, two sphenoidal turbinated, the
frontal, and eleven of the face — two nasal, two superior maxillary, two lachrymal,
two palate, two inferior turbinated, and vomer.
Development of the Ckanium.
The development of the cranium takes place at a very early period, on account of the im-
portance of the organ it is intended to protect. In its most rudimentary state, it consists of a
thin membranous capsule; inclosing the cerebrum, and accurately moulded upon its surface.
This capsule is placed external to the dura mater, and in close contact with it; its walls are
continuous with the canal for the spinal cord, and the chorda dorsalis, or primitive part of the
vertebral column, is continued forwards, from the
spine, along the base, to its fore part, where it
terminates in a tapering point. The next step
in the process of development is the formation
of cartilage. This is deposited in the base of
the skull, in two symmetrical segments, one on
either side of the median line ; these subsequently
coalesce, so as to inclose the chorda dorsalis :
the chief part of the cerebral capsule still re-
taining its membranous form. Ossification first
takes place in the roof, and is preceded by the
deposition of a membranous blastema upon the
surface of the cerebral capsule, in which the ossi-
fying process extends ; the primitive membranous
capsule becoming the internal periosteum, and
being ultimately blended with the dura mater.
Although the bones of the vertex of the skull
appear before those at the base, and make con-
siderable progress in their growth, at birth ossifi-
cation is more advanced in the base, this portion
of the skull forming a solid immovable ground-
work.
Fie. 41.-
-Skull at Birth, showing the Anterior
and Posterior Fontanelles.
The Fontanelles (figs. 41 and 42).
Before birth, the bones at the vertex and side
of the skull are separated from each other by
membranous intervals, in which bone is deficient.
These intervals, at certain parts, are of consider-
able size, and are termed the fontanelles, so
called from the pulsations of the brain, which
resemble the rising of water at a fountain head.
The fontanelles are four in number, and corre-
spond to the junction of the four angles of the
parietal with the contiguous bones. The ante-
rior fontanelle is the largest, and corresponds to
the junction of the sagittal and coronal sutures;
the posterior fontanelle, of smaller size, is situ-
ated at the junction of the sagittal and lambdoid
sutures ; the two remaining ones are situated at
Fig. 42.— The Lateral Fontanelles.
80 OSTEOLOGY.
the inferior angles of the parietal bone. The latter are closed soon after birth ; the two at the
superior angles remain open longer, the posterior one being closed in a few months after birth,
the anterior one remaining open until the first or second year. These spaces are gradually tilled
in by an extension of the ossifying process, or by the development of a Wormian bone. Fine
specimens of large "Wormian bones closing in the anterior and posterior fontanelles, and replacing
the anterior inferior angle of the parietal bones, exist in the St. George's Hospital Museum.
Sometimes, the anterior fontanelle remains open beyond two years, and is occasionally persistent
throughout life.
Supernumerary or Wormian Bones.
When ossification of any of the tabular bones of the skull proves abortive, the membranous
interval left unclosed is usually tilled in by a supernumerary piece of bone, which is developed
from a separate centre, and gradually extends until it fills in the vacant space. These supernu-
merary pieces are called Wormian bones ;' they are called also, from their form, ossa triquetra,
and present much variation in situation, number, and size.
They occasionally occupy the situation of the fontanelles. Bertin, Cruveilhier, and Cuvier
have each noticed the presence of one in the anterior fontanelle. There are two specimens in the
Museum of St. George's Hospital, which present Wormian bones in this situation. In one, the
skull of a child, the supernumerary piece is of considerable size, and of a quadrangular form.
They are occasionally found in the posterior fontanelle, appearing to replace the superior angle
of the occipital bone. Not unfrequently, there is one replacing the extremity of the great wing
of the sphenoid, or the anterior inferior angle of the parietal bone, in the fontanelle there situated.
They have been found in the different sutures on the vertex and side of the skull, and in some
of those at the base. They are most frequent in the lambdoid. Ward mentions an instance 'in
which one half of the lambdoid suture was formed by large AVormian bones disposed in a double
row, and jutting deeply into each other;' and refers to similar specimens described by Dumontier
and Bourgery.
A deficiency in the ossification of the flat bones would appear in some cases to be symmetrical
on the two sides of the skull; for it is not uncommon to find these supernumerary bones corre-
sponding in form, size, and situation on each side. Thus, in several instances, I have seen a pair
of large Wormian bones symmetrically placed in the lambdoid suture ; in another specimen, a
pair in the coronal suture, with a supernumerary bone in the spheno-parietal suture of both sides.
The size of these supernumerary pieces varies, in some cases not being larger than a pin's head,
and confined to the outer table ; in other cases so large, that one pair of these bones formed the
whole of that portion of the occipital bone above the superior curved lines, as described 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, struc-
ture, and mode of articulation, they resemble the other cranial bones.
Congenital Fissures and Gaps.
Mr. Humphry has called attention to the existence of congenital fissures, not unfrequently
found in the cranial bones, as the result of incomplete ossification. These fissures have been
noticed in the frontal and parietal bones, and the squamous portion of the temporal; they extend
from the margin towards the middle of the bone, and are of great interest in a medico-legal point
of view, as they are liable to be mistaken for fractures. An arrest of the ossifying process may
also give rise to the deficiencies or gaps occasionally found in the cranial bones. Such deficien-
cies are said to occur most frequently when ossification is imperfect, and to be situated near the
natural apertures for vessels. Mr. Humphry describes such deficiencies to exist in a calvarium,
in the Cambridge Museum, where a gap sufficiently large to admit the end of the finger is seen
on either side of the sagittal suture, in the place of the parietal foramen. There is a specimen
precisely similar to this in the Museum of St. George's Hospital ; and another, in which a small
circular gap exists in the parietal bone of a young child, just above the parietal eminence.
Similar deficiencies are not unfrequently met with in hydrocephalic skulls ; being most frequent,
according to Mr. Humphry, in the frontal bones, and in the parietal bones, on either side of the
sagittal suture.
BONES OF THE FACE.
The Facial Bones are fourteen in number, viz.,
Two Nasal, Two Palate,
Two Superior Maxillary, Two Inferior Turbinated,
Two Lachrymal, Vomer,
Two Malar, Inferior Maxillary.
' Wormius, a physician in Copenhagen, is said to have given the first detailed description of
these bones.
SUPERIOR MAXILLARY BONE.
81
Fig. 43.— Right Nasal Bone.
Frontal B,
4th
Fig. 44. — Right Nasal Bone.
<Wt/th
frontal Sfjnn&.
crest
— Opposite bone.
Outer Surface,.
Inn
with
Rrpertdicalar
.Plate of Ethmoid;
groove for nasal nc rvc
Surface
Nasal Bones.
The Nasal Bones are two small oblong bones, varying in size and form in different
individuals ; they are placed side by side at the middle and upper part of the face,
forming, by their junction, the "bridge" of the nose. Each bone presents for
examination two sur-
faces, and four borders.
The outer surface is
concave from above
downwards, convex
from side to side ; it is
covered by the Com-
pressor naris muscle,
marked by numerous
small arterial furrows,
and perforated about
its centre by a foramen,
sometimes double, for
the transmission of a
small vein. Sometimes
this foramen is absent
on one or both sides, and occasionally the foramen caecum opens on this surface.
The inner surface is concave from side to side, convex from above downwards ; in
which direction it is traversed by a longitudinal groove, sometimes a canal, for
the passage of a branch of the nasal nerve. The superior border is narrow, thick,
and serrated for articulation with the nasal notch, of the frontal bone. The inferior
border is broad, thin, sharp, directed obliquely downwards, outwards, and back-
wards, and serves for the attachment of the lateral cartilage of the nose. This
border presents about its centre a notch, which transmits 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.
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. 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 with the nasal spine
of the frontal above, and the perpendicular plate of the ethmoid below.
Development. By one centre for each bone, whicli appears about the same period
as in the vertebrae.
Articulations. With four bones : two of the cranium, the frontal and ethmoid ;
and two of the face, the opposite nasal and the superior maxillary.
No muscles are directly attached to this bone.
Superior Maxillary Bone.
The Superior Maxillary Bone is one of the most important bones of the face in
a surgical point of view, on account of the number of diseases to which some of
its parts are liable. Its minute examination becomes, therefore, a matter of
considerable interest. It is the largest bone of the face, excepting the lower jaw ;
and forms, by its union with its fellow of the opposite side, the whole of the upper
jaw. Each bone assists in the formation of three cavities, the roof of the mouth,
the floor and outer wall of the nose, and the floor of the orbit ; enters into the
formation of two fossae, the zygomatic, and spheno-maxillary ; and two fissures,
the spheno-maxillary, and pterygo-maxillary. Each bone presents for examina-
tion a body, and four processes, malar, nasal, alveolar, and palatine.
The body is somewhat quadrilateral, and is hollowed out in its interior to form
a large cavity, the antrum of Highmore. It presents for examination four
6
82
OSTEOLOGY.
surfaces, an external or facial, a posterior or zygomatic, a superior or orbital,
and an internal.
The external or facial surface (fig. 45) is directed forwards and outwards. In
the median line of the bone, just above the incisor teeth, is a depression, the
incisive or myrtiform fossa, which gives1 origin to the Depressor alse nasi. Above
and a little external to it, the Compressor naris arises. More external, is another
depression, the canine fossa, 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 infra-orbital foramen, the termination of the
infra-orbital canal ; it transmits the infra-orbital nerve and artery. Above the
infra-orbital foramen is the margin of the orbit, which affords partial attachment
to the Levator labii superioris proprius.
The posterior or zygomatic surface is convex, directed backwards and outwards,
and forms part of the zygomatic fossa. It presents about its centre several aper-
tures leading to canals in the substance of the bone ; they are termed the posterior
dental canals, and transmit the posterior dental vessels and nerves. At the lower
Fig. 45. — Left Superior Maxillary Bone, Outer Surface.
Outer Surface .
Incisive fossa
Posterior Dental Cunab
xtlla.ru Tulerositu.
■Bicuspids
part of this surface is a rounded eminence, the maxillary tuberosity, especially
prominent after the growth of the wisdom-tooth, rough on its inner side for
articulation with the tuberosity of the palate bone. Immediately above the rough
surface is a groove, which, running obliquely down on the inner surface of the
bone, is converted into a canal by articulation with the palate bone, forming the
posterior palatine canal.
The superior or orbital surface is thin, smooth, triangular, and forms part of
the floor of the orbit. It is bounded internally by an irregular margin which
articulates, in front, with the lachrymal ; in the middle, with the os planum of
the ethmoid ; behind, with the orbital process of the palate bone ; 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 ; and in front, by part of the circumference of the orbit,
SUPERIOR MAXILLARY BONE.
83
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
infra-orbital, for the passage of the infra-orbital nerve and artery. This groove
commences at the middle of the outer border of this surface, and, passing forwards,
terminates in a canal which subdivides into two branches ; one of the canals, the
infra-orbital, opens just below the margin of the orbit ; the other, which is smaller,
runs in the substance of the anterior wall of the antrum ; it is called the anterior
dental canal, transmitting the anterior dental vessels and nerves to the front teeth
of the upper jaw. At the inner and fore part of the orbital surface, just external
to the lachrymal canal, is a minute depression, which gives origin to the Inferior
oblique muscle of the eye.
The internal surface (fig. 46) is unequally divided into two parts by a horizontal
projection of bone, the palate process; that portion above the palate process forms
part of the outer wall of the nose; the portion below it forms part of the cavity
of the mouth. The superior division of this surface presents a large irregular
shaped opening leading into the antrum of Highmore. At the upper border of
Fig. 46. — Left Superior Maxillary Bone. Inner Surface.
$°r,'r partially closinj Orfae of Antrum
murk/d in ourJiitt,
■Ethmoid —
Inferior Turbinated-
JPaLue
Ant. JVa*aZ Spin*
JS-rletle
pans id through
Ant. palat. Canal
this aperture are a number of 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 nose, traversed
by a fissure, the maxillary fissure, which runs from the lower part of the orifice of
the antrum obliquely downwards and forwards, and receives the maxillary process
of the palate bone. Behind it is a rough surface which articulates with the per-
pendicular plate of the palate bone, traversed by a groove which, commencing near
the middle of the posterior border, runs obliquely downwards and forwards, and
forms, when completed by its articulation with the palate bone, the posterior palatine
canal. In front of the opening in the antrum is a deep groove, converted into a
canal by the lachrymal and inferior turbinated bones, and lodging the nasal duct.
More anteriorly is a well-marked rough ridge, the inferior turbinated crest, for
articulation with the inferior turbinated bone. The concavity above this ridge
forms part of the middle meatus of the nose ; whilst that# below it forms part of
the inferior meatus. The inferior division of this surface is concave, rough and
U OSTEOLOGY.
uneven, and perforated by numerous small foramina for the passage of nutrient
vessels.
The Antrum of Highmore, or Maxillary Sinus, is a large triangular-shaped
cavity, hollowed out of the body of the maxillary bone ; its apex, directed out-
wards, is formed by the malar process ; its base, by the outer wall of the nose.
Its walls are everywhere exceedingly thin, its roof being formed by the orbital
plate ; its floor by the alveolar process, bounded in front by the facial surface, and
behind by the zygomatic. Its inner wall, or base, presents, in the disarticulated
bone, a large irregular aperture, which communicates with the nasal fossae. The
margins of this aperture are thin and ragged, and the aperture itself is much con-
tracted by its articulation with the ethmoid above, the inferior turbinated below,
and the palate bone behind. In the articulated skull, this cavity communicates
with the middle meatus of the nose, generally by two small apertures left between
the above-mentioned 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.
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
are 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 ; 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 forwards on to
the cheek, and making its way backwards into the zygomatic fossa, and down-
wards into the mouth.
The Malar Process is a rough triangular eminence, situated at the angle of
separation of the facial from the zygomatic surface. In front, it is concave,
forming part of the facial surface ; behind, it is also concave, and forms part of the
temporal fossa ; above, it is rough and serrated for articulation with the malar
bone ; whilst, below, a prominent ridge marks the division between the facial and
zygomatic surfaces.
The Nasal Process is a thick triangular plate of bone, which projects upwards,
inwards, and backwards, by the side of the nose, forming part of its lateral
boundary. Its external surface is concave, smooth, perforated by numerous fora-
mina, and gives attachment to the Levator labii superioris alaeque nasi, the
Orbicularis palpebrarum, and Tendo oculi. Its internal surface forms part of the
inner wall of the nose ; it articulates above with the frontal, and presents a rough
uneven surface, which articulates with the ethmoid bone, closing in the anterior
ethmoid cells ; below this is a transverse ridge, the superior turbinated crest, for
articulation with the middle turbinated bone of the ethmoid, bounded below by a
smooth concavity, which forms part of the middle meatus ; below this is the inferior
turbinated crest, already described, for articulation with the inferior turbinated
bone ; and still more inferiorly, the concavity which forms part of the inferior
meatus. The anterior border of the nasal process is thin, directed obliquely
downwards and forwards, and presents a serrated edge for articulation with the nasal
bone : its posterior border is thick, and hollowed into a groove for the nasal 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 surgeon in the performance of the operation for
fistula lacrymalis. The lachrymal groove in the articulated skull is converted
into a canal by the lachrymal bone, and lachrymal process of the inferior tur-
binated; it is directed downwards, and a little backwards and outwards, is about
the diameter of a goose-quill, slightly narrower in the middle than at either
extremity, and lodges the nasal duct.
SUPERIOR MAXILLARY BONE.
85
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. These cavities are eight in number, and vary in size and depth according
to the teeth they contain : those for the canine teeth being the deepest ; those for
the molars being widest, and subdivided into minor cavities ; those for the incisors
being single, but deep and narrow.
The Palate Process, thick and strong, projects horizontally inwards from the
inner surface of the bone. It is much thicker in front than behind, and forms a
considerable part of the floor of the nares, and the roof of the mouth. Its upper
surface is concave from side to side, smooth, and forms part of the floor of the
nose. In front is seen the upper orifice of the anterior palatine (incisor) canal,
which leads into a fossa formed by the junction of the two superior maxillary
bones, and is situated immediately behind the incisor teeth. It transmits the ante-
rior palatine vessels, the naso-palatine nerves passing through the intermaxillary
suture. The inferior surface, also concave, is rough and uneven, and forms part
of the roof of the mouth. This surface is perforated by numerous foramina for
the passage of nutritious vessels, channelled at the back part of its alveolar border
by a longitudinal groove, sometimes a canal, for the transmission of the posterior
palatine vessels, and a large nerve, and presents little depressions for the lodgment
of the palatine glands. This surface presents anteriorly the lower orifice of the
anterior palatine fossa. In some bones, a delicate linear suture may be seen
extending from the anterior palatine fossa to the interval between the lateral
incisor and the canine teeth. This marks out the intermaxillary bone, which in
some animals exists permanently as a separate piece. It includes the whole thick-
•ness 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 outer
border of the palate process is
firmly united with the rest of the FiS- 47.— Development of Superior Maxillary Bone. By
bone. The inner border is thicker Four Centres'
in front than behind, raised above
into a ridge, which, with the cor-
responding ridge in the opposite
bone, forms a groove for the re-
ception of the vomer. The an-
terior margin is bounded by the
thin concave border of the open-
ing of the nose, prolonged for-
wards internally into a sharp
process, forming, with a similar
process of the opposite bone, the
anterior nasal spine. The pos-
terior border is serrated for
articulation with the horizontal
plate of the palate bone.
Development. This bone is
formed at such an early period,
and ossification proceeds in it
with such rapidity, that it has
been found impracticable hither-
to to determine with accuracy
its number of centres. It ap-
pears, however, probable that it has four centres of development, viz., one for the
nasal and facial portions, one for the orbital and malar, one for the incisive, and
one for the palatal portion, including the entire palate except the incisive segment.
The incisive portion is indicated in young bones by a fissure, which marks off a
small segment of the palate, including the two incisor teeth. In some animals, this
remains permanently as a separate piece, constituting the intermaxillary bone : and
J for Natal fy
Facial port?}
J for Orbital Rr
Malar port".'
Anterior Surface.
at
Birth
1 fur In
port1!
1 for Palatal jiorlVf
86 OSTEOLOGY.
in the human subject, where the jaw is malformed, as in cleft palate, this segment
may be separated from the maxillary bone by a deep fissure extending backwards
between the two into the palate. If the fissure be on both sides, both segments are
quite isolated from the maxillary bones, and hang from the end of the vomer, not
unfrequently being much displaced, and often accompanied by congenital fissure of
die upper lip, either on one or both sides of the median line. The maxillary sinus
appears at an earlier period than any of the other sinuses, its development com-
mencing about the fourth month of fcetal life.
Articulations. With nine bones : two of the cranium — the frontal and ethmoid,
and seven of the face, viz., the nasal, malar, lachrymal, inferior turbinated, palate,
vomer, and its fellow of the opposite side. Sometimes it articulates with the
orbital plate of the sphenoid.
Attachment of Muscles. Orbicularis palpebrarum, Obliquus inferior oculi, Leva-
tor labii superioris aloeque nasi, Levator labii superioris proprius, Levator anguli
oris, Compressor naris, Depressor alas nasi, Masseter, Buccinator.
The Lachrymal Bones.
The Lachrymal Bones are the smallest and most fragile bones of the face, situated
at the front part of the inner wall of the orbit, and resemble somewhat in form,
thinness, and size, a finger-nail ; hence they are termed
Fig. 48.— Left Lachrymal the ossa unguis. Each bone presents for examination two
Bone. External Surface, surfaces and four borders. The external or orbital surface
v;a Frontal (fig- 48) is divided by a vertical ridge into two parts. The
portion of bone in front of this ridge 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 lodges the lachrymal sac ; the lower part assists in
the formation of the lachrymal canal, and 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, and part of the orbital surface imme-
itfe*-**^ diately behind it, afford attachment to the Tensor tarsi:
(Sliyfaly inlarrjcd \ the ridge terminates below in a small hook-like process,
which articulates with the lachrymal tubercle of the supe-
rior maxillary bone, and completes the upper orifice of
the lachrymal canal. It sometimes exists as a separate piece, which is then
called the lesser lachrymal bone. The internal or nasal surface presents a depressed
furrow, corresponding to the ridge on its outer surface. The surface of bone in
front of this forms part of the middle meatus ; and that behind it articulates
with the ethmoid bone, filling in the anterior ethmoidal cells. 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 posterior part articulating with the
orbital plate of the superior maxillary bone ; the anterior portion being pro-
longed downwards into a pointed process, which articulates with the lachrymal
process of the inferior turbinated bone, assisting in the formation of the lachrymal
canal.
.Development. By a single centre, which makes its appearance soon after ossi-
fication of the vertebrae 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. The Tensor tarsi.
MALAR BONE.
87
Bn.sde* passed through
T£'mpo70-Mala.r (iintds
The Malar Bones.
The Malar Bones are two small quadrangular bones, situated at the upper and
outer part of the face, forming the prominence of the cheek, part of the outer wall
and floor of the orbit, and part of the temporal and zygomatic fossae. Each bone
presents for examination an external and an internal surface ; four processes, the
frontal, orbital, maxillary, and zygomatic ; and four borders. The external surface
(fig. 49) is smooth, convex, perforated near its centre by one or two small
apertures, the malar foramina, for the passage of nerves and vessels, covered
by the Orbicularis palpebrarum
muscle, and afibrds attachment Fig. 49.— Left Malar Bone. Outer Surface.
to the Zygomaticus major and
Zygomaticus minor muscles.
The internal surface (fig. 50),
directed backwards and inwards,
is concave, presenting internally
a rough triangular surface, for
articulation with the superior
maxillary bone ; and externally,
a smooth concave surface, which
forms the anterior boundary of
the temporal fossa above, wider
below, where it forms part of
the zygomatic fossa. This sur-
face presents, a little above its
centre, the aperture of one or two
malar canals, and affords attach-
ment to part of two muscles, the
Temporal above, and the Masse-
ter below. Of the four processes,
the frontal is thick and serrated,
and articulates with the external
angular process of the frontal
bone. The orbital process is a
thick and strong plate, which
projects backwards from the
orbital margin of the bone. Its
upper surface, smooth and con-
cave, forms, by its junction with
the great ala of the sphenoid,
the outer wall of the orbit. Its
under surface, smooth and con-
vex, forms part of the temporal
fossa. Its anterior margin is
smooth and rounded, forming
part of the circumference of the
orbit. Its superior margin, rough,
and directed horizontally, arti-
culates with the frontal bone
behind the external angular pro-
cess. Its posterior margin is rough and serrated, for articulation with the sphenoid :
internally 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 sometimes seen ; this forms the anterior
Fig. 50. — Left Malar Bone. Inner Surface.
88 OSTEOLOGY.
boundary of the spheno-maxillary fissure: occasionally, no such non-articulai
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 the orifices of one or two temporo-malar canals ; 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. The maxillary process is a rough triangular surface, which articulates with
the superior maxillary bone. The zygomatic process, long, narrow, and serrated,
articulates with the zygomatic process of the temporal bone. Of the four borders,
the superior or orbital is smooth, arched, and forms a considerable part of the
circumference of the orbit. The inferior or zygomatic is continuous with the
lower border of the zygomatic arch, affording attachment by its rough edge to the
Masseter muscle. The anterior 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 outer margin to the Levator labii superioris proprius, just at its
point of junction with the superior maxillary. The posterior or temporal border,
curved like an italic/, 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.
Development. By a single centre of ossification, which appears at about the
same period when ossification of the vertebrae commences.
Articulations. With four bones ; three of the cranium, the frontal, sphenoid, and
temporal ; and one of the face, the superior maxillary.
Attachment of Muscles. Levator labii superioris proprius, Zygomaticus major
and Zygomaticus minor, Masseter, and Temporal.
The Palate Bones.
The Palate Bones are situated at the back part of the nasal fossa3 ; they are two
in number, one on each side, wedged in between the superior maxillary and the
pterygoid process of the sphenoid. 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 three fossae, the zygomatic, spheno-
maxillary, and pterygoid. In form, the palate bone somewhat resembles the letter
L, and may be divided into an inferior or horizontal plate, and a superior or
vertical plate.
The Horizontal Plate is thick, of a quadrilateral form, and presents two surfaces
and four borders. The superior surface, concave from side to side, forms the back
part of the floor of the nares. The inferior 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 the aponeurosis of the
Tensor palati muscle. At the outer extremity of this ridge is a deep groove, con-
verted into a canal by its articulation with the tuberosity of the superior maxil-
lary bone, and forming the posterior palatine canal. Near this groove, the orifices
of one or two small canals, accessory posterior palatine, may frequently be seen.
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 spine, for the attachment of the
Azygos uvulae. The external border is united with the lower part of the perpen-
dicular plate almost at right angles. The internal border, the thickest, is serrated
for articulation with its fellow of the opposite side ; the superior edge is raised
into a ridge, which, united with the opposite bone, forms a crest in which the
vomer is received.
PALATE BOXE.
89
The Vertical Plate (fig. 51) is thin, of an oblong form, and directed upwards
and a little inwards. It
Fig. 51. — Left Palate Bone. Internal View (enlarged).
Sup
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McuriHary
J'rocets
HORIZONTAL PLATE
presents two surfaces, an
external and an internal,
and four borders.
The internal surface pre-
sents at its lower part a
broad shallow depression,
which forms part of the
inferior meatus of the nose.
Immediately above this is
a well-marked horizontal
ridge, the inferior turbi-
nated crest, for articula-
tion with the inferior tur-
binated bone; above this,
a second broad shallow
depression, which forms
part of the middle meatus,
surmounted above by a
horizontal ridge, less pro-
minent than the inferior,
the superior turbinated
crest, for articulation with
the middle turbinated bone. Above the superior turbinated crest is a narrow
horizontal groove, which forms part of the superior meatus.
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
zygomatic fossa ; it is also smooth in front, where it covers the orifice of the
antrum. Towards the back part of this surface is a deep groove, converted into a
canal, the posterior palatine, by its articulation with the superior maxillary bone.
It transmits the posterior palatine vessels and a large nerve. The anterior border
is thin, irregular, and presents opposite the inferior turbinated crest a pointed
projecting lamina, the maxillary process, which is directed forwards, and closes
in the lower and back part of the opening of the antrum, being received into a
fissure that exists at the inferior part of this aperture. The posterior border
(fig. 52) 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,
which is received into the angular interval between the two pterygoid plates of
the sphenoid at their inferior extremity. This process presents at its back part
three grooves, a median and two lateral ones. The former is smooth, and forms
part of the pterygoid fossa, affording attachment to the Internal pterygoid muscle ;
whilst the lateral grooves are rough and uneven, for articulation with the anterior
border of each pterygoid plate. The base of this process, continuous with the
horizontal portion of the bone, presents the apertures of the accessory descending
palatine canals ; whilst its outer surface is rough, for articulation with the inner
surface of the body of the superior maxillary bone. 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.
The Orbital Process, directed upwards and outwards, is placed on a higher
level than the sphenoidal. It presents five surfaces, which inclose a hollow cellu-
lar cavity, and is connected to the perpendicular plate by a narrow constricted
neck. Of these five surfaces, three are articular, two non-articular or free sur-
faces. The three articular are the anterior or maxillary surface, which is directed
90
OSTEOLOGY.
forwards, outwards, and downwards, is of an oblong form, and rough for articulation
with the superior maxillary bone. The posterior or sphenoidal surface is directed
backwards, upwards, and inwards. It ordinarily presents a small half-cellular
cavity which communicates with
Fig. 52. — Left Palate Bone. Posterior View (enlarged)
the sphenoidal sinus,
margins of which are
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and the
serrated
for- articulation with the vertical
part of the sphenoidal turbinated
bone. The internal or ethmoidal
surface is directed inwards, up-
wards and forwards, and articu-
lates with the lateral mass of the
ethmoid bone. In some cases,
the cellular cavity above-men-
tioned opens on this surface of
the bone; it then communicates
with the posterior ethmoidal
cells. More rarely it opens on
both surfaces, and then commu-
nicates with the posterior eth-
moidal cells, and the sphenoidal
sinus. The non-articular or free
surfaces are the superior or or-
bital, directed upwards and out-
wards, of triangular form, concave,
smooth, articulating with tne superior maxillary bone, and forming the back
part of the floor of the orbit. The external or zygomatic surface, directed out-
wards, backwards and downwards, is of an oblong form, smooth, and forms part
of the zygomatic fossa. This surface is separated from the orbit by a smooth
rounded border, which enters into the formation of the spheno-maxillary fissure.
The Sphenoidal Process of the palate bone is a thin compressed plate, much
smaller than the orbital, and directed upwards and inwards. It presents three
surfaces and two borders. The superior surface, the smallest of the three, arti-
culates with the horizontal part 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 pterygoid process
of the sphenoid; the latter is smooth, and forms part of the zygomatic fossa.
The anterior border forms the posterior boundary of the spheno-palatine foramen.
The posterior border, serrated at the expense of the outer table, articulates with
the inner surface of the pterygoid process.
The orbital and sphenoidal processes are separated from one another by a deep
notch, which is converted into a foramen, the spheno-palatine, by articulation with
the sphenoidal turbinated bone. Sometimes the two processes are united above,
and form between them a complete foramen, or the notch is crossed by one or
more spicula of bone, so as to form two or more foramina. In the articulated
skull, this foramen opens into the back part of the outer wall of the superior
meatus, and transmits the spheno-palatine vessels and nerves.
Development. From a single centre, which makes its appearance at the angle of
junction of the two plates of the bone. From this point ossification spreads, in-
wards, to the horizontal plate ; downwards, into the tuberosity ; and upwards, into
the vertical plate. In the foetus, the horizontal plate is much longer than the
vertical ; and even after it is fully ossified, the whole bone is remarkable for its
shortness.
Articulations. "With seven bones: the sphenoid, ethmoid, superior maxillary,
inferior turbinated, vomer, opposite palate, and sphenoidal turbinated.
INFERIOR TURBINATED BONE.
9J
Attachment of Muscles. The Tensor palati, Azygos uvulae, Internal and External
pterygoid.
The Inferior Turbinated Bones.
The Inferior Turbinated Bones are situated one on each side of the outer wall of
the nasal fossse. Each bone consists of a layer of thin spongy bone, curled
upon itself like a scroll, hence its name "turbinated;" and extends horizontally
across the outer wall of the nasal fossa, immediately below the orifice of the
antrum. Each bone presents two surfaces, two borders, and two extremities.
The internal surface (fig. 53) is convex, perforated by numerous apertures, and
traversed by longitudinal grooves
Fig. 53. — Right Inferior Turbinated Bone.
Surface.
Inner
Fig.
54. — Right Inferior Turbinated Bone.
Outer Surface.
and canals for the lodgment of arte-
ries and veins. In the recent state it
is covered by the lining membrane of
the nose. The external surface is con-
cave (fig. 54), and forms part of the
inferior meatus. Its upper border is
thin, irregular, and connected to vari-
ous bones along the outer wall of the
nose. . It may be divided into three
portions; of these, the anterior arti-
culates 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 lachry-
mal process, for it articulates with the ante-
rior 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 lachrymal canal. At the junction of
the two middle fourths of the bone, but en-
croaching on the latter, a broad thin plate, the ethmoidal process, ascends to join
the unciform process of the ethmoid ; from the lower border of this process, a thin
lamina of bone curves downwards and outwards, hooking over the lower edge of
the orifice of the antrum, which it narrows below ; it is called the maxillary pro-
cess, and fixes the bone firmly on to the outer wall of the nasal fossa. The infe-
rior border is free, thick and cellular in structure, more especially in the centre
of the bone. Both extremities are more or less narrow and pointed. If the bone
is held so that its outer concave surface is directed backwards (i. e., towards the
holder), and its superior border, from which the lachrymal and ethmoidal pro-
cesses project, upwards, the lachrymal process will be directed to the side to which
the bone belongs.
Development. By a single centre which makes its appearance about the middle
of foetal 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.
92
OSTEOLOGY.
•"^A. Sup -M«*
&. ^
The Vomer.
The Vomer is a single bone, situated vertically at the back part of the nasal
fossae, forming part of the septum of the nose. It is thin, somewhat like a
ploughshare in form ; but it varies in different individuals, being frequently bent
to one or the other side; it
Fig. 55.— Vomer. presents for examination two
surfaces and four borders.
The lateral surfaces are smooth,
marked with small furrows for
the lodgment of bloodvessels,
and by a groove on each side,
sometimes a canal, the naso-
palatine, which runs obliquely
downwards and forwards to
the intermaxillary suture be-
tween the two anterior palatine
canals; it transmits the naso-
palatine nerve. The superior
border, the thickest, presents
a deep groove, bounded on
each side by a horizontal pro-
jecting ala of bone ; the groove
receives the rostrum of the sphenoid, whilst the alas are overlapped and retained
by laminae (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 bloodvessels to the substance of the
bone. The inferior border, the longest, is broad and uneven in front, where it
articulates with the two superior 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, between which is received the perpendicular
plate of the ethmoid, the lower half consisting of a single rough edge, also occa-
sionally channelled, which is united to the triangular cartilage of the nose. The
posterior border is free, concave, and separates the nasal fossae behind. It is
thick and bifid above, thin below.
Development. The vomer at an early period consists of two laminae separated
by a very considerable interval, and inclosing between them a plate of cartilage
which is prolonged forwards to form the remainder of the septum. Ossification
commences in it at about the same period as in the vertebrae, the coalescence of the
laminae taking place from behind forwards, but is not complete until after puberty.
Articulations. With six bones: two of the cranium, the sphenoid and ethmoid;
and four of the face, the two superior maxillary and the two palate bones ; and with
the cartilage of the septum.
The vomer has no muscles attached to it.
The Inferior Maxillary Bone.
The Inferior Maxillary Bone, the largest and strongest bone of the face, serves
for the reception of the inferior teeth. It consists of a curved horizontal portion,
the body, and of two perpendicular portions, the rami, which join the former
nearly at right angles behind.
The Horizontal portion or body (fig. 56), is convex in its general outline, and
curved somewhat like a horseshoe. It presents for examination two surfaces
and two borders. The external surface is convex from side to side, concave
from above downwards. In the median line is a vertical ridge, the symphysis ; it
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. On either side of the symphysis, just below the roots of the
o
INFERIOR MAXILLARY BONE.
93
incisor teeth, is a depression, the incisive fossa, for the attachment of the Levator
menti ; and, still more externally, a foramen, the mental foramen, for the passage
of the mental nerve and artery. This foramen is placed just below the root of
the second bicuspid tooth. Running outwards from the base of the mental process
on each side, is a well-marked ridge, the external oblique line. This ridge is at
first nearly horizontal, but afterwards inclines upwards and backwards, and is
continuous with the anterior border of the ramus ; it affords attachment to the
Depressor labii inferioris and Depressor anguli oris; below these the Platysma
myoides is inserted. The external oblique line, and the internal oblique or
mylo-hyoidean line, to be hereafter described, divide the body of the bone into
a superior or alveolar, and an inferior or basilar portion.
Fig. 56. — Inferior Maxillary Bone. Outer Surface. Side View.
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Men ial
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The internal surface (fig. 57) is concave from side to side, convex from above
downwards. In the middle line is an indistinct linear depression, 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, and afford attachment, the upper pair to the
Genio-hyoglossi muscles, the lower pair to the Genio-hyoidei muscles. Sometimes
the tubercles on each side are blended into one, or they all unite into an irregular
eminence of bone, or 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 oval depression,
the sublingual fossa, 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. At the back part of the sublingual fossa, the internal oblique
or mylo-hyoidean line commences ; it is at first faintly marked, but becomes more
distinct as it passes upwards and outwards, and is especially prominent opposite
the last two molar teeth ; it divides the lateral surface of the bone into two por-
tions, and affords attachment throughout its whole extent to the Mylo-hyoid
muscle, the Superior constrictor being attached above its posterior extremity,
nearer the alveolar margin. The portion of bone above this ridge is smooth, and
covered by the mucous membrane of the mouth ; whilst that below it presents
an oblong depression, the submaxillary fossa, wider behind than in front, for the
lodgment of the submaxillary gland. The superior or alveolar border is wider,
and its margins thicker, behind than in front. It is hollowed into numerous
cavities, for the reception of the teeth; these are sixteen in number, and vary in
depth and size according to the teeth which they contain. The inferior border is
rounded, longer than the superior, and thicker in front than behind ; it presents
94
OSTEOLOGY.
a shallow groove, just where the body joins the ramus, over which the facial
artery turns.
The Perpendicular Portions or Rami are of a quadrilateral form. Each
presents for examination two surfaces, four borders, and two processes. The
external surface is flat, marked with ridges, and gives attachment throughout
nearly the whole of its extent to the Masseter muscle. The internal surface pre-
sents about its centre the oblique aperture of the inferior dental canal, 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,
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, which
runs obliquely downwards 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 descends
obliquely downwards and forwards in the substance of the ramus, and then hori-
zontally forwards 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
Fig. 57. — Inferior Maxillary Bone. Inner Surface. Side View.
>^^
CENIO-HYO-CLOSSUS
CEN10-HY0IDCU5
Mylo-hyoid Ridge
Bod
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, runs nearest the internal sur-
face of the jaw ; and in the anterior third, nearer its external surface. Its walls
are composed of compact tissue at either extremity, 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. The upper border
of the ramus is thin, and presents two processes, separated by a deep concavitv,
the sigmoid notch. Of these processes, the anterior is the coronoid, the posterior
the condyloid.
The Coronoid Process is a thin, flattened, triangular eminence of bone, which
varies in shape and size in different subjects, and serves essentially for the attach-
ment of the Temporal muscle. Its external surface is smooth, and affords
attachment to the Masseter and Temporal muscles. Its internal surface gives
attachment to the Temporal muscle, and presents the commencement of a longi-
tudinal ridge, which is continued to the posterior part of the alveolar process. On
the outer side of this ridge is a deep groove, continued below on the outer side of
INFERIOR MAXILLARY BONE. 9S
the alveolar process ; this ridge and part of the groove afford attachment, above,
to the Temporal ; below, to the Buccinator muscle.
The Condyloid Process, shorter but thicker than the coronoid, consists of two
portions : the condyle, and the constricted portion which supports the condyle, the
neck. 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 backwards, and from
side to side, the articular surface extending further on the posterior than on the
anterior surface. The neck of the condyle is flattened from before backwards,
and strengthened by ridges which descend from the fore part and sides of the
condyle. Its lateral margins are narrow, and present externally a tubercle for
the external lateral ligament. Its posterior surface is convex; its anterior is
hollowed out on its inner side by a depression, the pterygoid fossa, for the attach-
ment of the External pterygoid muscle. 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, which 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; and, between them, is the
attachment of the stylo-maxillary ligament. 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 Sigmoid Notch, separating the two processes, is a deep semilunar depression,
crossed by the masseteric artery and nerve.
Development. This bone is formed at such an early period of life, before, indeed,
any other bone, excepting the clavicle, that it has been found impossible at present
to determine its earliest condition. It appears probable, however, that it is devel-
oped by two centres, one for each lateral half, the two segments meeting at the
symphysis, where they become united. Additional centres have also been
described for the coronoid process, the condyle, the angle, and the thin plate of
bone which forms the inner side of the alveolus.
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.
At birth (fig. 58), the bone consists of two lateral halves, united by fibro-cartilaginous tissue,
in which one or two osseous nuclei are generally found. The body is a mere shell of bone, con-
taining the sockets of the two incisor, the canine, and the first 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, from the
jaws not being as yet separated by the eruption of the teeth.
After birth (fig. 59), the two segments of the bone become joined at the symphysis, from below
upwards, 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 espe-
cially 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 snbdental 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.
In the adult (fig. 60), 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, 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. 61), 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,
the chief part of the bone is beloiv 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, and the angle
obtuse.
8£
OSTEOLOGY.
Side "View of the Lower Jaw at different Periods of Life.
Fig. 58.— At Birth.
Fig. 59.— At Puberty.
Fig. 60.— In the Adult.
Fig. 61.— In Old Age.
SUTURES OF THE SKULL. 97
Articulations. With the glenoid fossae of the two temporal bones.
Attachment of Muscles. By its external surface, commencing at the symphysis
and proceeding backwards : Levator menti, Depressor labii inferioris, Depressor
anguli oris, Platysma myoides, Buccinator, Masseter. By its internal surface, com-
mencing at the same point; Genio-hyo-glossus, Genio-hyoideus, Mylo-hyoideus,
Digastricus, Superior constrictor, Temporal, Internal pterygoid, External pterygoid.
THE SUTURES.
The bones of the cranium and face are connected to each other by means of
sutures. The dentations by which they are joined are confined to the external
table, the edges of the internal table lying merely in apposition with the contiguous
bone. The Cranial Sutures may be divided into three sets: 1. Those at the ver-
tex 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 three, the sagittal, coronal, and lamb-
doid.
The Sagittal Suture (interparietal) is formed by the junction of the two parietal
bones, and extends from the middle of the frontal bone, backwards to the superior
angle of the occipital. In childhood, and occasionally in the adult, when the two
halves of the frontal bone are not united, it is continued forwards to the root of the
nose. This suture sometimes presents, near its posterior extremity, the parietal
foramen on each side ; and in front, where it joins the coronal suture, a space is
occasionally left, which incloses a large Wormian bone.
The Coronal Suture (fronto-parietaT) extends transversely across the vertex
of the skull, and connects the frontal with the parietal bones. It commences at
the extremity of the great wing of the sphenoid on one side, and terminates at the
same point on the opposite side. The dentations of this 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.
The Lambdoid Suture (occipitoparietal), 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 upwards to the
end of the sagittal suture. The dentations of this suture are very deep and dis-
tinct, and are often interrupted by several small Wormian bones.
The sutures at the side of the skull are also three in number: the spheno-parietal,
squamo-parietal, and masto-parietal. They are subdivisions of a single suture,
formed between the lower border of the parietal, and the temporal and sphenoid
bones, and which extends from the lower end of the lambdoid suture behind, to
the lower end of the coronal suture in front.
The Spheno-parietal 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, 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 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 of the base of the skull are, the basilar in the centre, and, on each
side, the petro-occipital and masto-occipital, the petro-sphenoidal and the squamo-
sphenoidal.
The Basilar Suture 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 inseparably united. Between the outer extremity of the basilar suture,
and the termination of the lambdoid, an irregular suture exists which is subdivided
into two portions. The inner portion, formed by the union of the petrous part of
the temporal with the occipital bone, is termed the petro-occipital. The outer
7
98 OSTEOLOGY.
portion, formed by the junction of the mastoid part of the temporal with the occi-
pital, is called the masto-occipital. 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 ; 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.
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 consideration is
the transverse. 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 superior
maxillary, and the nasal bones on each side.
The sutures remain separate for a considerable period after the complete forma-
tion 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, and the
interposition of the sutural ligament between the bones forming them, prevents
the dispersion of blows or jars received upon the skull. Mr. 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 Skull.
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.
Veetex of the Skull.
The Superior Region or Vertex presents two surfaces, an external, and an internal.
The External Surface is bounded, in front, by the nasal eminences, and super-
ciliary 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 external angular process
of the frontal. This surface includes 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 backwards by the sagittal, which terminates behind in the lambdoid.
From before backwards 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 pos-
teriorly the smooth convex surface of the occipital bone.
The Internal Surface is concave, presenting eminences and depressions for the
convolutions of the cerebrum, and numerous furrows for the lodgment of branches
of the meningeal arteries. Along the middle line of this surface is a longitudinal
groove, narrow in front, where it terminates in the frontal crest : broader behind ;
it lodges the superior longitudinal sinus, and its margins afford attachment to the
falx cerebri. On either side of it are several depressions for the Pacchionian
bodies, and at its back part, the internal openings of the parietal foramina. This
surface is crossed, in front, by the coronal suture ; from before backwards, by the
sagittal ; behind, by the lambdoid.
BASE OP THE SKULL.
99
Base of the Skull.
The Inferior Region or Base of the skull presents two surfaces, an internal or
cerebral, and an external or basilar.
Fig. 62.— Base of the Skull. Inner or Cerebral Surface.
Groove for Super. "Lmoititd. Sinus
Qroovtt for Avter. Meiiiiitjfal A
Foramen t'otruiti
Crista GtiMi
Slit for Vttml nervtk.
Qrooi't Jnr Tfvtxnlj nerve.
Anterior Ethmoidal For.
Orifioee far Olfactory verve
Posterior Etlimaidal Fort
.Ethmoidal Spine -
Olfactory Croats
Optic Foravun
Optic Oroovt-
Olivary pre,
Anterior Clinoid proa
Middle Clinoid proc
Foste rio r Clinoid proa
Groove for 6'$ nerve
Tor" laeerum medium.
Orifice of Carotid, Canal
Depression for Casserian Ganglion
Meatus Auditor. Tntemris
Slit for Vara -Ma Wr
Sup. Petrosal groove
For. laeerum poster itu
Anterior Condyloid For
Aqueduct. Veetibuli
Posterior Condyloid For.
Mastoid Foe
Lost. Meningeal Grooves.
100 OSTEOLOGY.
The Internal or Cerebral Surface (fig. 62) presents three fossae on each side,
called the anterior, middle and posterior fossae of the cranium.
The Anterior Fossa is formed by the orbital plate of the frontal, the cribriform
plate of the ethmoid, the ethmoidal process and lesser wing of the sphenoid. It
is the most elevated of the three fossae, convex externally 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 ethmoido-frontal,
ethmo-sphenoidal, and fronto-sphenoidal ; and lodges the anterior lobe of the cere-
brum. It presents, in the median line, from before backwards, the commencement
of the groove for the superior longitudinal sinus, and crest for the attachment of
the falx cerebri; the foramen caecum, this aperture being formed by the frontal and
crista galli of the ethmoid, and, if pervious, transmitting a small vein from the nose
to the superior longitudinal sinus. Behind the foramen caecum is the crista galli,
the posterior margin of which affords attachment to the falx cerebri. On either
side of the crista galli is the olfactory groove, which supports the bulb of the
olfactory nerve, perforated by three rows of orifices which give passage to its
filaments; and in front by a slit-like opening, which transmits the nasal branch
of the ophthalmic nerve. On the outer side of each olfactory groove are the
internal openings of the anterior and posterior ethmoidal foramina; the former,
situated about the middle of its outer margin, transmits the nasal nerve, which
runs in a groove along its surface to the slit-like opening above mentioned; whilst
the latter, the posterior ethmoidal foramen, opens at the back part of the margin
under cover of a projecting lamina of the sphenoid ; it transmits the posterior
ethmoidal artery and vein to the posterior ethmoidal cells. Further back in the
middle line is the ethmoidal spine, bounded behind by an elevated ridge, sepa-
rating a longitudinal groove on each side which supports the olfactory nerve.
The anterior fossa presents laterally eminences and depressions for the convolu-
tions of the brain, and grooves for the lodgment of the anterior meningeal arteries.
The Middle Fossa, somewhat deeper than the preceding, is narrow in the middle,
and becomes wider as it expands laterally. It is bounded in front by the posterior
margin of the lesser wing of the sphenoid, the anterior clinoid process, and the
anterior margin of the optic groove; behind, by the petrous portion of the tem-
poral, and basilar suture; externally, by the squamous portion of the temporal,
and anterior inferior angle of the parietal bone ; and is separated from its fellow by
the sella Turcica. It is traversed by four sutures, the squamous, sphenoparietal,
spheno-temporal, and petro-sphenoidal.
In the middle line, from before backwards, is the optic groove, which supports
the optic commissure, terminating on each side in the optic foramen, for the
passage of the optic nerve and ophthalmic artery ; behind the optic groove is
the olivary process, and laterally the anterior clinoid processes, which afford
attachment to the folds of the dura mater, which form the cavernous sinuses.
Separating the middle fossae is the sella Turcica, a deep depression, which lodges
the pituitary gland, bounded in front by a small eminence on either side, the
middle clinoid process, and behind by a broad square plate of bone, surmounted
at each superior angle by a tubercle, the posterior clinoid process; beneath the
latter process is a groove, for the lodgment of the sixth nerve. On each side of the
sella Turcica is the cavernous groove; it is broad, shallow, and curved somewhat
like the Italic letter/: it commences behind at the foramen lacerum medium, and
terminates on the inner side of the anterior clinoid process. This groove lodges
the cavernous sinus, the internal carotid artery, and the orbital nerves. The sides
of the middle fossa are of considerable depth; they present eminences and depres-
sions for the middle lobes of the brain, and grooves for lodging the branches of
the middle meningeal artery ; the latter commence on the outer side of the fora-
men spinosum, and consist of two large branches, an anterior and a posterior ; the
former passing upwards and forwards to the anterior inferior angle of the parietal
bone, the latter passing upwards and backwards. The following foramina may
also be seen from before backwards. Most anteriorly is the foramen lacerum
BASE OF THE SKULL. 101
anterius, or sphenoidal fissure, formed above by the lesser wing of the sphenoid ;
below, by the greater wing ; internally, by the body of the sphenoid ; and com-
pleted externally by the orbital plate of the frontal bone. It transmits the third,
fourth, the three branches of the ophthalmic division of the fifth, the sixth nerve,
and the ophthalmic vein. Behind the inner extremity of the sphenoidal fissure
is the foramen rotundum, for the passage of the second division of the fifth or
superior maxillary nerve ; still more posteriorly is seen a small orifice, the foramen
Vesalii; this opening is situated between the foramen rotundum and foramen ovale,
a little internal to both ; it varies in size in different individuals, and transmits a small
vein. It opens below in 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 fifth or inferior maxillary nerve, the small
meningeal artery, and the small petrosal nerve. 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, the foramen lacerum medium. The
lower part of this aperture is filled up with cartilage in the recent state. On the
anterior surface of the petrous portion of the temporal bone is seen, from without
inwards, the eminence caused by the projection of the superior semicircular canal,
and the groove leading to the hiatus Fallopii, for the transmission of the petrosal
branch of the Vidian nerve; beneath it, the smaller groove, for the passage of the
smaller petrosal nerve ; and near the apex of the bone, the depression for the
Casserian ganglion, and the orifice of the carotid canal, for the passage of the
internal carotid artery and carotid plexus of nerves.
The Posterior Fossa, deeply concave, is the largest of the three, and situated on
a lower level than either of the preceding. It is formed by the occipital, the
petrous and mastoid portions of the temporal, and the posterior inferior angle of
the parietal bone ; is crossed by three sutures, the petro-occipital, masto-occipital,
and masto-parietal ; and lodges the cerebellum, pons Varolii, and medulla oblon-
gata. It is separated from the middle fossa in the median line by the basilar
suture, and on each side by the superior border of the petrous portion of the
temporal bone. This serves for the attachment of the tentorium cerebelli, is
grooved externally for the superior petrosal sinus, and at its inner extremity pre-
sents a notch, upon which rests the fifth nerve. Its circumference 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 ligaments; and a little above these are seen the
internal openings of the anterior condyloid foramina. In front of the foramen
magnum is the basilar process, grooved for the support of the medulla oblongata
and pons Varolii, and articulating on each side with the petrous portion of the tem-
poral 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. This foramen is partially subdi-
vided into two parts ; the posterior and larger division transmits the internal jugu-
lar vein, the anterior the eighth pair of nerves. Above the jugular foramen is the
internal auditory foramen, for the auditory and facial nerves and auditory artery;
behind and external to this is the slit-like opening leading into the aquaeductus
vestibuli; whilst between the two latter, and near the superior border of the
petrous portion, is a small triangular depression, which lodges a process of
the dura mater, and occasionally transmits a small vein into the substance of the
bone. Behind the foramen magnum are the inferior occipital fossae, which lodge
the lateral lobes of the cerebellum, separated from one another by the internal
occipital crest, which serves for the attachment of the falx cerebelli, and lodges
the occipital sinuses. These fossae are surmounted, above, by the deep transverse
grooves for the lodgment of the lateral sinuses. These channels, in their passage
outwards, groove the occipital bone, the posterior inferior angle of the parietal, the
mastoid portion of the temporal, and the occipital just behind the jugular foramen,
at the back part of which they terminate. Where this sinus grooves the mastoid
102 OSTEOLOGY.
part of the temporal bone, the orifice of the mastoid foramen may be seen ; and,
just previous to its termination, it has opening into it the posterior condyloid
foramen.
The External Surface of the base of the skull (fig. 63) is extremely irregular.
It is bounded in front by the incisor teeth in the upper jaws ; behind, by the
superior curved lines of the occipital bone ; and laterally, by the alveolar 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 two superior maxillary
and palate bones, the vomer, the pterygoid, under surface of the great wing,
spinous process and part of the body of the sphenoid, the under surface of the
squamous, mastoid, and petrous ' portions of the temporal, and occipital bones.
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 ; they
vary in depth and size according to the teeth they contain. Immediately behind
the incisor teeth is the anterior palatine fossa. At the bottom of this fossa may
usually be seen four apertures, two placed laterally, which open above, one in the
floor of each nostril, and transmit the anterior palatine vessels, and two in
the median line of the intermaxillary suture, one in front of the other, the most
anterior one transmitting the left, and the posterior one (the larger) the right
naso-palatine nerve. These two latter 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 palatal glands, and crossed by a crucial
suture, which indicates the point of junction of the four bones of which it is com-
posed. One or two small foramina, seen in the alveolar margin behind the incisor
teeth, occasionally seen in the adult, almost constant in young subjects, are called the
incisive foramina ; they transmit nerves and vessels to the incisor teeth. At each
posterior angle of the bard palate is the posterior palatine foramen, for the trans-
mission of the posterior palatine vessels and anterior palatine nerve, and running
forwards and inwards from it a groove, which lodges the same vessels and nerve.
Behind the posterior palatine foramen is the tuberosity of the palate bone, per-
forated by one or more accessory posterior palatine canals, and marked by the
commencement of a ridge, which runs transversely inwards, and serves for the
attachment of the tendinous expansion of the Tensor palati. muscle. Projecting
backwards from the centre of the posterior border of the hard palate is the pos-
terior nasal spine, for the attachment of the Azygos uvulae. Behind and above
the hard palate is the posterior aperture 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 laterally by the pterygoid processes of the sphenoid.
Each aperture measures about an inch in the vertical, and 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 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, 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 pterygoid 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 to the External pterygoid muscle.
BASE OF THE SKULL.
103
Behind the nasal fossa) in the middle line is the basilar surface of the occipital
bone, presenting in its centre the pharyngeal spine for the attachment of the
Fig. 63.— Base of the Skull. External Surface.
Ant. pala/tim fossa
'mnsmits left Naso-palat. n.
Transmit* A<nz. palat vess.
Transmits riyht Na so pala t.n.
deces sary palatine
Foram-i na .
■Pflft.NastU Spin*.
AilOOt UVULA
Ila inula r jj rot:
SpJienoid.proc. of Palate-.
1'ttrijtjo-ualatt ii€ C.
-T.ENSOR TVMPANI.
PJtxiry7Ufca.lSpinr.firr 8UP. CONSTRICT.
Sif tfEittttuAuin tti* k CamtlferTentrrTyrm,
lajatof TrmpxMi.
Ctiiuil Jot Jacobs on i n.
Aqueduct. CtfchUa.
""* For. lore rii- mpusterai s.
Ca.na.lft/rJlrnoUty it.
.Xu.riculo.r fissiiig
104 OSTEOLOGY.
Superior constrictor muscle of the pharynx, with depressions on each side for the
insertion of the Rectus anticus major and minor. At the base of the external
pterygoid plate is the foramen ovale ; behind this, the foramen spinosum, and the
prominent spinous process of the sphenoid, which gives attachment to the internal
lateral ligament of the lower jaw and the Laxator tympani muscle. External to
the spinous process is the glenoid fossa, divided into two parts by the Glaserian
fissure, the anterior portion being concave, smooth, bounded in front by the emi-
nentia articularis, and serving for the articulation of the condyle of the lower jaw;
the posterior portion rough, bounded behind by the vaginal process, and serving
for the reception of part of the parotid gland. Emerging from between the lamina?
of the vaginal process 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-mastoid foramen is the auricular fissure for
the auricular branch of the pneumogastric, bounded behind by the mastoid process.
Upon the inner side of the mastoid 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 portion 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 opening is filled up in the recent state
by a fibro-cartilaginous substance ; across its upper or cerebral aspect pass the
internal carotid artery and Vidian nerve. 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 tem-
poral bone, presenting from within outwards the quadrilateral rough surface,
part of which affords attachment to the Levator palati and Tensor tympani .
muscles; external to this surface are the orifices of the carotid canal and the
aquaeductus cochlea?, 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 and vein to the cochlea. Behind the
carotid canal is a large aperture, the jugular fossa, formed in front by the petrous
portion of the temporal, and behind by the occipital; it is general^ larger on the
right than on the left side; and towards its cerebral aspect is divided into two parts
by a ridge of bone, which projects usually from the temporal, the anterior or smaller
portion transmitting the three divisions of the eighth pair of nerves ; the posterior
transmitting the internal jugular vein and the ascending meningeal vessels, from
the occipital and ascending pharyngeal arteries. On the ridge of bone dividing
the carotid canal from the jugular fossa, is the small foramen for the transmission
of the tympanic nerve; and on the outer wall of the jugular foramen, near the
root of the styloid process, is the small aperture for the transmission of Arnold's
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
alar ligaments, and presenting externally a rough surface, the jugular process,
which serves for the attachment of the Rectus lateralis. On either side of each
condyle anteriorly is the anterior condyloid fossa, perforated by the anterior con-
dyloid foramen, for the passage of the hypoglossal nerve. Behind each condyle
are the posterior condyloid fossae, perforated on one or both sides by the posterior
condyloid foramina, 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 the bone between them,
being rough for the attachment of numerous muscles.
LATERAL REGION OF THE SKULL.
105
Lateral Region of the Skull.
The Lateral Region of the Skull is somewhat of a triangular form, its oase being
formed by a line extending from the external angular process of the frontal bone
along the temporal ridge backwards to the outer extremity of the superior curved
line of the occiput : and the sides being formed by two lines, the one drawn
downwards and backwards from the external angular process of the frontal bone
to the angle of the lower jaw, the other from the angle of the jaw upwards and
backwards to the extremity of the superior curved line. This region is divisible
into three portions, temporal, mastoid, and zygomatic.
G4.— Side View of the Skull.
Frenlal
'artelal
The Temporal Fossae.
The Temporal fossa is bounded above and behind by the temporal ridge, which
extends from the external angular process of the frontal upwards and backwards
across the frontal and parietal bones, curving downwards behind to terminate at
the root of the zygomatic process. 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, squamous portion of the temporal, and malar
bones, and is traversed by five sutures, the transverse facial, coronal, spheno
parietal, squamo-parietal, and squamo-sphenoidal. It is deeply concave in front,
convex behind, traversed by grooves for lodging branches of the deep temporal
arteries, and filled by the Temporal muscle.
106 OSTEOLOGY.
The Mastoid Portion is bounded in front by the anterior root of the zygoma ;
above, by a line which runs from the posterior root of the zygoma to the end of
the masto-parietal suture ; -behind and below, by the masto-occipital suture. It
is formed by the mastoid and part of the squamous portion of the temporal bone ;
its surface is convex and rough for the attachment of muscles, and presents, from
behind forwards, the mastoid foramen, the mastoid process, the external auditory
meatus, surrounded by the auditory process, and, most anteriorly, the glenoid
fossa, bounded in front by the eminentia articularis, behind by the vaginal process.
The Zygomatic Fossae.
The Zygomatic fossa is an irregular-shaped cavity, situated below, and on the
inner side of the zygoma ; bounded, in front, by the tuberosity of the superior
maxillary bone and the ridge which descends from its malar process"; behind,
by the posterior border of the pterygoid process ; above, by the pterygoid ridge
on the outer surface of the great wing of the sphenoid and 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 jaw. It contains the lower part of the Temporal, the External and
Internal pterygoid muscles, the internal maxillary artery, the inferior maxillary
nerve, and their branches. At its upper and inner part may be observed two
fissures, the spheno-maxillary and pterygo-maxillary.
The Spheno-maxillary fissure, 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 external border of the
orbital surface of the superior maxillary and a small part of the palate bone ;
externally, by a small part of the malar bone ; internally, it joins at right angles
with the pterygo-maxillary fissure. This fissure opens a communication from the
orbit into three fossa?, the temporal, zygomatic, and spheno-maxillary; it transmits
the superior maxillary nerve, infra-orbital artery, and ascending branches from
Meckel's ganglion.
The Pterygo-maxillary fissure is vertical, and descends at right angles from
the inner extremity of the preceding ; it is an elongated interval, formed by the
divergence of the superior maxillary bone from the pterygoid process of the
sphenoid. It serves to connect the spheno-maxillary fossa with the zygomatic,
and transmits branches of the internal maxillary artery.
The Spheno-Maxillaey Fossa.
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; in front, by the superior maxillary bone; behind, by the
pterygoid process 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 three fossa?, the orbital, nasal, and
zygomatic, and with the cavity of the cranium, and has opening into it five fora-
mina. Of these there are three on the posterior wall, the foramen rotundum
above, the Vidian below and internal, and, still more inferior and internal, the
pterygo-palatine. On the inner wall is the spheno-palatine foramen by which it
communicates with the nasal fossa, and below, the superior orifice of the posterior
palatine canal, besides occasionally the orifices of two or three accessory posterior
palatine canals.
Anterior Eegion of the Skull.
The Anterior Eegion of the Skull, which forms the face, is of an oval form,
presents an irregular surface, and is excavated for the reception of the two prin-
cipal organs of sense, the eye and the nose. It is bounded above by the nasal
ANTERIOR REGION OF THE SKULL.
101
eminences 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 downwards, the nasal eminences, which
indicate the situation of the frontal sinuses ; diverging' outwards from the nasal
eminences are the superciliary ridges which support the eyebrows. Beneath the
nasal eminences are 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 downwards, presenting in the median line the inter-nasal
suture, formed between the nasal bones, laterally the naso-maxillary suture,
formed between the nasal bone and the nasal process of the superior maxillary
bones, both these sutures terminating above in that part of the transverse suture
Fig. 65. — Anterior Region of the Skull.
1&0K'**?* hone
TIN DO OCULI
JLnten-or
JVarea
Ant. Nasal Spin*
Jncis-ivc, fossa
Orcove far TtLtstal a Y
which connects the nasal bones and nasal processes of the superior maxillary
with the frontal. Below the nose is seen the heart-shaped opening of the ante-
rior nares, the narrow end upwards, and broad below ; it presents laterally the
thin sharp margins which serve for the attachment 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,
and on each side of it the incisive fossa. Beneath this fossa is the alveolar- pro-
cess of the upper and lower jaw, containing the incisor teeth, and, at the- lower
part of the median line, the symphysis of the chin, the mental eminence,, ami the
incisive fossa of the lower jaw.
Proceeding from above downwards, on each side, is the supra-orbital ridge.
103 OSTEOLOGY.
terminating externally in the external angular process at its junction with the
malar, and internally in the internal angular process ; towards the inner third of
this ridge is the supra-orbital notch or foramen, for the passage of the supra-
orbital vessels and nerve, and at its inner side a slight depression for the attach-
ment of the cartilaginous pulley of the Superior oblique muscle. Beneath the
supra-orbital 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, supe-
rior maxillary, and lachrymal bones ; internally, by the nasal process of the supe-
rior maxillary, and 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 infra-orbital foramen, the termination of the infra-orbital canal, and, beneath
this, the canine fossa, which gives attachment to the Levator anguli oris ; bounded
below by the alveolar processes, containing the teeth of the upper and lower jaw.
Beneath the alveolar arch of the lower jaw are the mental foramen for the passage
of the mental nerve and artery, 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.
The Orbits.
The Orbits (fig. 65) are two quadrilateral hollow cones, situated at the upper
and anterior part of the face, their bases being directed forwards and outwards,
and their apices backwards and inwards. Each orbit 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, a circumfer-
ence or base, and an apex. The Roof is concave, directed downwards and for-
wards, and formed in front by the orbital plate of the frontal ; behind, by the
lesser wing of the sphenoid. This surface presents internally the depression for
the nbro-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 is nearly flat, and 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 malar, and behind, by the orbital surface of the palate.
This surface presents at its anterior and internal part, just external to the lachry-
mal canal, a depression for the attachment of the Inferior oblique muscle ; exter-
nally, 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.
The Inner Wall is flattened, and formed from before backwards 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 crest of the lachrj^mal bone, and the sutures connecting the ethmoid,
in front, with the lachrymal, behind, with the sphenoid.
The Outer Wall is formed in front by the orbital process of the malar bone ;
behind, by the orbital plate 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 backwards, the suture connecting the frontal
with the malar in front, and with the orbital plate of the sphenoid behind ; quite
posteriorly is the foramen lacerum anterius, or sphenoidal fissure, which transmits
the third, fourth, ophthalmic division of the fifth and sixth nerves, 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 with the
hcoxymal in front, and with the ethmoid behind. This suture is perforated by
NASAL F0SSJ3. 109
two foramina, the anterior and posterior ethmoidal, the former transmitting
the anterior ethmoidal artery and nasal nerve, the latter the posterior ethmoidal
artery and vein. The inferior external angle, formed by the junction of the outer
wall and floor, presents the spheno-maxillary fissure, which transmits the infra-
orbital vessels and nerve, and the ascending branches from the spheno-palatine
ganglion. The inferior internal angle is formed by the union of the lachrymal bone
and os planum of the ethmoid, with the superior maxillary and palate bones. The
circumference or base of the orbit, quadrilateral in form, is bounded above by the
supra-orbital arch ; below, by the anterior border of the orbital plate of the malar,
superior maxillary, and lachrymal bones; externally, by the external angular
process of the frontal and the malar bone ; 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 supra-orbital notch
or foramen, for the passage of the supra-orbital artery, veins, and nerve. The
apex, situated at the back of the orbit, corresponds to the optic foramen, 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 lacerum anterius, spheno-maxillary fissure, supra-orbital fora-
men, infra-orbital canal, anterior and posterior ethmoidal foramina, malar foramina,
and lachrymal canal.
The Nasal Fossae.
The Nasal Fossse are two large irregular cavities, situated in 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. They communicate by two
large apertures, the anterior nares, with the front of the face ; and with the pharynx
behind by the two posterior nares. These fossae are much 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.
Each nasal fossa communicates with four sinuses, the frontal above, the sphenoidal
behind, and the maxillary and ethmoidal on either side. Each fossa also commu-
nicates with four cavities: with the orbit by the lachrymal canal, 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.
The upper wall or roof (fig. 66) is long, narrow, and concave from before back-
wards ; it is formed in front by the nasal bones and nasal spine of the frontal,
which are directed downwards and forwards ; in the middle, by the cribriform
lamella of the ethmoid, which is horizontal ; and behind, by the under surface of
the body of the sphenoid, and sphenoidal turbinated bones, which are directed
downwards and backwards. This surface presents, from before backwards, the
internal aspect of the nasal bones ; on their outer side, the suture formed between
the nasal, with 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 articulates with Its fellow of the opposite side ; whilst the
surface of the bones is perforated by a few small vascular apertures, and presents
the longitudinal groove for the nasal nerve : further back is the transverse suture,
connecting the frontal with the nasal in front, and the ethmoid behind, the olfactory
foramina on the under surface of the cribriform plate, and the suture between it
and the sphenoid behind : quite posteriorly are seen the sphenoidal turbinated
bones, the orifices of the sphenoidal sinuses, and the articulation of the ulae of the
vomer with the under surface of the body of the sphenoid.
110
OSTEOLOGY.
The floor is flattened from before backwards, 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 backwards, the anterior nasal spine ; behind this,
the upper orifice 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.
Fig. 66.— Roof, Floor, and Outer Wall of Nasal Fossa*.
Eaof i . . .
Xasal jJoiu. \ aA // Peobe f*—* thmujt*
Xv / {-^^v n-^Naso-lachrymal Canal
'.rial fyimof Frenital Bon* ^v \\^m^\)
,„, ,Vti i ^\ \. / flllMY Brittle passed 'through
Orruontuimu rfMthmd ^ \ Uilll §A Injurdvbalam .
Outer Wall
-^fnsal Roc. of Suffix
Lachrymal
f'.tlinaiid.
Vticijcnmrroc cf ditto
Inf trior Turbinated
Palate
Superior Meatus
Middle Meatus
.jcrior Meatus
Tloor
Ant.Na.scil SjJin£
Pa late 1'roc. of Sup- Max. ■
Palate Proc. of Palate-
Post. Nasal Spine
Ant. Palatine Canal
The inner wall or septum (fig. 67) is a thin vertical partition, which separates
the nasal fossje from one another ; it is occasionally perforated so that the fossae
communicate, and it is frequently deflected considerably to one side. It is formed,
in front, by the crest of the nasal bones and nasal spine of the frontal ; in the
middle, by the perpendicular lamella of the ethmoid ; behind, by the vomer and
rostrum of the sphenoid; below, by the crest of the superior maxillary and palate
bones. It presents, in front, a large triangular notch, which receives the triangular
cartilage of the nose : above, the lower orifices of the olfactory canals ; and behind,
the guttural edge of the vomer. Its surface is marked by numerous vascular and
nervous canals, and traversed by sutures connecting the bones of which it is
formed.
The outer wall is formed, in front, by the nasal process of the superior maxillary
and lachrymal bones ; in the middle, by the ethmoid and inner surface of the
superior maxillary and inferior turbinated bones ; behind, by the vertical plate of
the palate bone. This surface presents three irregular longitudinal passages or
meatuses, formed between three horizontal plates of bone that spring from it; they
are termed the superior, middle, and inferior meatuses of the nose. The superior
meatus, the smallest of the three, is situated at the upper and back part of each
nasal fossa, occupying 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 at the back part of its outer wall, the posterior ethmoidal cells
OS HTOIDES.
Ill
at the front part of the upper wall. The opening of the sphenoidal sinuses is
usually at the upper and back part of the nasal fossae, immediately behind the
superior turbinated bone. The middle meatus is situated between the middle and
inferior turbinated bones, and occupies the posterior two-thirds of the outer wall
of the nasal fossa. It presents two apertures. In front is the orifice of the infun-
dibulum, by which the middle meatus communicates with the anterior ethmoidal
cells, and through these with the frontal sinuses. At the centre of the outer wall
Fig. t'7. — Inner Wall of Nasal Fossae, or Septum of Nose.
Crest of battel Ion,.
Masai Spin* <•{ Frontal ft.
Space for Triangular
Cartilage of Septum
Crest of Palate Bone
Crest of Stip.AIaocill.E,,*
is the orifice of the antrum, which varies somewhat as to its exact position in
different skulls. The inferior meatus, 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 wallof the nose, is broader in front than behind, and
presents anteriorly the lower orifice of the lachrymal canal.
Os Hyoides.
The Hyoid bone is named from its resemblance to the Greek Upsilon ; it is also
called the lingual bone, from supporting the tongue, and giving attachment to its
numerous muscles. It is a bony arch, shaped
like a horseshoe, and consisting of five seg-
ments, a central portion or body, two greater
cornua, and two lesser cornua.
The Body forms the central part of the
bone, is of a quadrilateral form, its anterior
surface (fig. 68), convex, directed forwards
and upwards, 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
divided into four muscular depressions. At
the point of meeting of these two lines is a
Fig. 68. — Hyoid Bone. Anterior Surface.
112 OSTEOLOGY.
prominent elevation, the tubercle. The portion above the horizontal ridge is
directed upwards, 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 ; and between these to part of the Hyo-glossus. The
posterior surface is smooth, concave, directed backwards and downwards, and
separated from the epiglottis by the thyro-hyoid membrane, and by a quantity
of loose areolar tissue. The superior border is rounded, and gives attachment to
the thyro-hyoid membrane, and part of the Genio-hyo-glossi muscles. The
inferior border gives attachment, in front, to the Sterno-hyoid ; behind, to part
of the Thyro-hyoid, and to the Omo-hyoid at its junction with the great cornu.
The lateral surfaces are small oval, convex facets, covered with cartilage for
articulation with the greater cornua.
The Greater Cornua project backwards from the lateral surfaces of the body;
they are flattened from above downwards, diminish in size from before backwards,
and terminate posteriorly in a tubercle for the attachment of the thyro-hyoid
ligament. Their outer surface 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.
The Lesser Cornua are two small conical-shaped eminences, attached by their
bases to the angles of junction between the body and greater cornua, and giving
attachment by their apices to the stylo-hyoid ligaments. In youth, the cornua are
connected to the body by cartilaginous surfaces, and held together by ligaments ;
in middle life, the body and greater cornua usually become joined ; and in old
age, all the segments are united together, forming a single bone.
Development. By five centres ; one for the body, and one for each cornu.
Ossification commences in the body and greater cornua towards the end of foetal
life, those of the cornua first appearing. Ossification of the lesser cornua com-
mences some months after birth.
Attachment of Muscles. Sterno-hyoid, Thyro-hyoid, Omo-hyoid, aponeurosis
of the Digastricus, Stylo-hyoid, Mylo-hyoid, Genio-hyoid, Genio-hyo-glossus,
Hyo-glossus, Middle constrictor of the pharynx, and occasionally a few fibres of
the Lingualis. It also gives attachment to the thyro-hyoidean membrane, and
the stylo-hyoid, thyro-hyoid, and hyo-epiglottic ligaments.
THE THOEAX.
The Thorax or Chest is an osseo-cartilaginous cage, intended to contain and
protect the principal organs of respiration and circulation. It is the largest of
the three cavities connected with the spine, and is formed by the sternum and
costal cartilages in front, the twelve ribs on each side, and the bodies of the dorsal
vertebras behind.
The Sternum.
The Sternum (figs. 69 and 70) is a flat narrow bone, situated in the median line
of the front of the chest, and consisting, in the adult, of three portions. Its form
resembles an ancient sword : the upper piece, representing the handle, is termed
the manubrium; the middle and largest piece, which represents the chief part of the
blade, is termed the gladiolus; and the inferior piece, like the point of the sword,
is termed the ensiform or xiphoid appendix. In its natural position, its direction
is oblique from above, downwards, and forwards. It is flattened 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 six inches, being rather longer in
the male than in the female.
The First Piece of the sternum, the Manubrium, is of a somewhat triangular
form, broad and thick above, narrow below at its junction with the middle piece.
Its anterior surface, convex from side to side, concave from above downwards, is
rrnooth, and affords attachment on each side to the Pectoralis major and sternal
STERNUM.
l\B
Fig. G9. — Sternum and Costal Cartilages. Anterior Surface.
S7IRNO-CLEI00. MASTOID
suacuwius - ^ <*'
Fig. 70. — Posterior Surface of Sternum.
Hi OSTEOLOGY.
origin of the Sterno-cleido-mastoid muscles. In well-marked bones, ridges limiting
the attachment of these muscles are very distinct. Its posterior surface, concave
and smooth, affords attachment on each side to the Stemo-hyoid and Sterno-thyroid
muscles. The superior border, the thickest, presents at its centre the interclavicular
notch; and, on each side, an oval articular surface, directed upwards, backwards,
and outwards, 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. The lateral
borders are marked above by an articular depression 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 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 downwards and inwards.
The Second Piece of the sternum, the gladiolus, considerably longer, narrower,
and thinner than the superior, is broader below than above. Its anterior surface
is nearly flat, directed upwards and forwards, and marked by three transverse lines
which cross the bone opposite the third, fourth, and fifth articular depressions.
These lines indicate the point of 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 backwards.
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 distinct 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. 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 separated by a series of curved interarticular intervals, which
diminish in length from above downwards, and correspond to the intercostal spaces.
The costal cartilage of each true rib, excepting the first, is thus seen to 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 their cartilages with the sternal column.
The Third Piece of the sternum, the ensiform or xiphoid appendix, 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. Its anterior
surface affords attachment to the costo-xiphoid ligaments. Its posterior surface,
to some of the fibres of the Diaphragm and Triangularis sterni muscles. Its
lateral borders, to the aponeurosis of the abdominal muscles. Above, it is con-
tinuous with the lower end of the gladiolus ; below, by its pointed extremity, it
gives attachment to the linea alba, and at each superior angle presents a facet for
the lower half of the cartilage of the seventh rib. 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. This bone is composed of delicate cancellated texture, covered by
a thin layer of compact tissue, which is thickest in the manubrium, between the
articular facets for the clavicles.
Development. The sternum, 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 eusiform appendix.
The sternum is entirely
cartilaginous up to the mid-
dle of foetal life, and when
ossification takes place, the
ossiiic granules are depo-
sited in the middle of the
intervals between the ar-
ticular depressions for the
costal cartilages, in the fol-
lowing order (fig. 71): in
the first piece, between the
fifth and sixth months;
in the second and third,
between the sixth and se-
venth months ; in 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 se-
cond and the seventeenth
or eighteenth years, by a
single centre which makes
its appearance at the upper
part, and proceeds gra-
dually downwards. To
these may be added the
occasional existence, as
described by Breschet, of
two small episternal cen-
tres, which make their ap-
pearance one on each side
of the interclavicular notch.
These are regarded by him
as the anterior rudiments
of a rib, of which the pos-
terior rudiment is the ante-
rior lamina of the trans-
verse process of the seventh
cervical vertebra. It occa-
sionally happens that some
of the segments are form-
ed from more than one
centre, the number and posi-
tion of which vary (fig. 73).
Thus the first piece may
have two, three, or even
six centres. "When two are
present, they are generally
situated one above the
other, the upper one being
STERNUM. 115
Fig. 71. — Development of Sternum, by Six Centres.
1 fori* piece fs-ti mo fc.'.il
cr K&Ttubritvm
Time
"J
Ajrpearctnce
U for 2V* piece
or
GlcvUolu,*
6 -J mo.
if. gthmr.
5. //-V'A
7uM
) for Era i 'form 1 . « j
J Cartilage )z~ ,8" *
Fi£
^ rarely anile ,
| except in old age
\ 3S-/rO.
I 20-25 fh year
J soon after pu.hertij
partly car/iiag incus in
advanxd life
Fi<rs. 73 and 74. Peculiarities.
for 1??j)tcee 2, or wore rent rat
number of
C enti'es
2?- pcece, usually one
%rd
/*$ ! 2 placed latera.Uij
And in
Mode of
Union-
Arrest of Devclopmert
of lateral pieces producing
Sternal fissure &
Sternal fora me n
116
OSTEOLOGY.
Fig-
75.— A Central Rib of Ri<
►Side. Inner Surface.
lit
the larger ; 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. 74),
or of the vertical fissure which some-
times intersects this part of the bone.
Union of the various centres commences
from below, and proceeds upwards, taking
place in the following order (fig. 72).
The fifth piece is joined to the fourth
soon after puberty ; the fourth to the third,
between the twentieth and twenty-fifth
years; the third to the second, between
the thirty-fifth and fortieth years; the
second is rarely joined to the first except
in very advanced age.
Articulations. With the clavicles, and
seven costal cartilages on each side.
Attachment of Muscles. The Pectora-
lis major, Sterno-cleido-mastoid, Sterno-
hyoid, Sterno-thyroid, Triangularis sterni,
aponeurosis of the Obliquus externus,
Obliquus interims, and Transversalis
muscles, Eectus and Diaphragm.
The Ribs.
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 increased
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 vertebro-
sternal or true ribs. The remaining five
are false ribs ; of these the first three,
being connected behind with the spine,
and in front with the costal cartilages,
are called the vertebro-costal ribs: the
last two are connected with the vertebras
only, being free at their anterior ex-
tremities; they are termed vertebral or
floating ribs. The ribs vary in their di-
rection, the upper ones being placed nearly
at right angles with the spine ; the lower
ones are placed obliquely, so that the
anterior extremity is lower than the
posterior. The extent of obliquity reaches
its maximum at the ninth rib, gradually
decreasing from that point towards the
twelfth. The ribs are situated one be-
neath the other in such a manner that
spaces are left between them ; these are
called intercostal spaces. Their length
corresponds to the length of the ribs;
ribs. m
their breadth is more considerable 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 downwards ; in each rib the greatest breadth is at the sternal extremity.
Common characters of the Ribs (fig. 75). Take a rib from the middle of the
series in order to study its common characters. Each rib presents two extremities,
a posterior or vertebral, an anterior or sternal, and an intervening portion, the
body or shaft. The posterior or vertebral extremity presents for examination a head,
neck, and tuberosity.
The head (fig. 76) is marked by a kidney-shaped articular surface, divided by
a horizontal ridge into two facets for articulation with the costal cavity formed
by the junction of the bodies of two contiguous dorsal vertebras ; the upper facet
is small, the inferior one of large size ; the ridge separating them serves for the
attachment of the interarticular ligament.
Fig. 76. — Vertebral Extremity of a Rib. External Surface.
fcr Ant.T Coifo-trmaLla* pr pt)st? fat+tnawUK
Tactl for hod.ii of tiyj>er Dor»al Vr/rtcbra.
Ridtjt f.rr Title r-artictdar L!yt~
facet for body of loutr Dorsal Viert'
far traiuv. vroc. of lomti
The neck is that flattened portion of the rib which extends outwards from the
head ; it is about an inch long and rests upon the transverse process of the lower
of the two vertebrae with which the head articulates. Its anterior surface is flat
and smooth, its posterior rough, for the attachment of the middle costo-transverse
ligament, and 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 presents a rough crest for the attachment of the anterior costo-
transverse ligament ; its inferior border is rounded. On the posterior surface of
the neck, just where it joins the shaft, and nearer the lower than the upper border,
is an eminence — the tuberosity ; it consists of an articular and a non-articular
portion. The articular portion, the most internal 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-arti-
cular portion is a rough elevation, which affords attachment to the posterior costo-
transverse ligament. The tubercle is much more prominent in the upper than in
the lower ribs.
The shaft is thin and flat, so as to present two surfaces, an external and an
internal; and two borders, a superior and an inferior. 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, downwards and outwards ;
this gives attachment to a tendon of the Sacro-lumbalis muscle, and is called the
angle. 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 anterior portion of the shaft, as far as the
angle, rests upon this margin, while the vertebral end of the bone, beyond the
angle, is bent inwards, and at the same time tilted upwards. 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. The portion of bone between
the angle and sternal extremity is also slightly twisted upon its own axis, the
external surface looking downwards behind the angle, a little upwards in front
of it. This surface presents, towards its sternal extremity, an oblique line, the
anterior angle. The internal surface is concave, smooth, directed a little upwards
118 OSTEOLOGY.
behind the angle ; a little downwards in front of it. This surface is marked by a
ridge ay Inch, commences 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 is deeply grooved, to lodge 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. Within the
groove are seen the orifices of numerous small foramina, which traverse the wall
•of the shaft obliquely from before backwards. The superior border, thick and
rounded, is marked by an external and an internal lip, more distinct behind than
in front ; they serve for the attachment of the External and Internal intercostal
muscles. The inferior border, thin and sharp, has attached the External intercostal
muscle. The anterior or sternal extremity is flattened, and presents a porous, oval,
concave depression, into which the costal cartilage is received.
Structure. The ribs consist of cancellous tissue, inclosed 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 body of the ribs at a very early period, before its appearance
in the vertebras. The epiphysis of the head, which is of a slightly angular shape,
and that for the tubercle, of a lenticular form, make their appearance between the
sixteenth and twentieth years, and are not united to the rest of the bone until
about the twenty-fifth year.
Attachment of Muscles. The Intercostals, Scalenus anticus, Scalenus medius,
Scalenus posticus, Pectoralis minor, Serratus magnus, Obliquus externus, Trans-
versalis, Quaclratus lumborum, Diaphragm, Latissimus dorsi, Serratus posticus
superior, Serratus posticus inferior, Sacro-lumbalis, Musculus accessorius ad sacro-
lumbalem, Longissimus dorsi, Cervicalis ascendens, Levatores costarum.
Peculiar Eibs.
The ribs which require especial consideration are five in number, viz., the first,
second, tenth, eleventh, and twelfth.
The first rib (fig. 77) is one of the shortest and the most curved of all the ribs ;
it is broad, flat, and placed horizontally at the upper part of the thorax, its surfaces
looking upwards and downwards, and its borders inwards .and outwards. The
head is of small size, rounded, and presents only a single articular facet for arti-
culation with the body of the first dorsal vertebra. The neck is narrow and
rounded. The tuberosity, thick and prominent, rests on the outer border. There
is no angle, and the shaft is not twisted on its axis. The upper surface of the shaft
is marked by two shallow depressions, separated from one another by a ridge,
which becomes more prominent towards the internal border, where it terminates
in a tubercle; this tubercle and ridge serve for the attachment of the Scalenus
anticus muscle, the groove in front of it transmitting the subclavian vein ; that
behind it, the subclavian artery. Between the groove for the subclavian artery
and the tuberosity, is a depression 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. The inner, concave,
thin, and sharp, and marked about its centre by the tubercle before mentioned.
The anterior extremity is larger and thicker than in any of the other ribs.
The second rib (fig. 78) is much longer than the first, but bears a very consider-
able resemblance to it in the direction of its curvature. The non-articular portion
of the tuberosity is occasionally only slightly marked. The angle is slight, and
situated close to the tuberosity, and the shaft is not twisted, so that both ends
RIBS.
119
touch any plane surface upon which it may be laid. The shaft is not horizontal,
like that of the first rib ; its outer surface, which is convex, looking upwards and
a little outwards. It presents, near the middle, a rough eminence for the attach-
ment of part of the first, and the second serration of the Serratus magnus. The
inner surface, smooth and concave, is directed downwards and a little inwards; it
presents a short groove towards its posterior part.
The tenth rib (fig. 79) has only a single articular facet on its head.
Peculiar Ribs.
Fig. 77. ,
Fig. 78
^t dost to tube/roti
iluwf
K^S
Fig. 79.
SinqU urtir.ula/r facet -
Fig. 80.
Single artie. fwmt —
Fig. 81.
iSingU turtle. fa,c
The eleventh and twelfth ribs (figs. 80 and 81) 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.
120 OSTEOLOGY.
The Costal Caetilages.
The Costal Cartilages (fig. 69) are white elastic structures, which serve to pro-
long the ribs forward to the front of the chest, and contribute very materially to
the elasticity of this cavity. The first seven are connected with the sternum, the
next three with the lower border of the cartilage of the preceding rib. The
cartilages of the last two ribs, which have pointed extremities, float freely 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 towards 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, whilst 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. The anterior surface is convex, and looks forwards
and upwards ; that of the first gives attachment to the costo-clavicular ligament ;
that of the first, second, third, fourth, fifth, and sixth, at their sternal ends, to the
Pectoralis major. The others are covered, and give partial attachment to some
of the great flat muscles of the abdomen. The posterior surface is concave, and
directed backwards and downwards, the six or seven inferior ones affording
attachment to the Transversalis and Diaphragm muscles. Of the two borders,
the superior is concave, the inferior convex ; they afford attachment to the Inter-
costal 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 smooth oblong surfaces at
the points where they articulate. Of the two extremities, the outer one is con-
tinuous 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 carti-
lages are pointed, and lie in contact 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. Under
certain diseased conditions, they are prone to ossify. Mr. Humphry's observa-
tions on this subject have led him to regard the ossification of the costal cartilages
as a sign of disease rather than of age. " The ossification takes place in the first
cartilage sooner than in the others ; and in men more frequently, and at an earlier
period of life, than in women."
Attachment of Muscles. The Subclavius, Sterno-thyroid, Pectoralis major,
Internal oblique, Transversalis, Pectus, Diaphragm, Triangularis sterni, Internal
and External intercostals.
OF TEE EXTEEMITIES.
The Extremities or limbs are those long-jointed appendages of the body, which
are connected to the trunk by one end, being free in the rest of their extent.
They are four in number : an upper or thoracic pair, connected with the thorax
through the intervention of the shoulder, and subservient mainly to tact and pre-
hension ; 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 in each, dependent on the peculiar offices they severally perform.
CLAVICLE. 121
OF THE UPPER EXTREMITY.
The upper extremity consists of the arm, the forearm, and the hand. Its con-
tinuity with the trunk is established by means of the shoulder, which is homo-
logous with the innominate or haunch bone in the lower limb.
OF THE SHOULDER.
The shoulder is placed upon the upper part and side of the chest, connecting
the upper extremity to the trunk ; it consists of two bones, the clavicle, and the
scapula.
The Clavicle.
The Clavicle (clavis, a key) or collar-bone forms the anterior portion of the
shoulder. It is a long bone, curved somewhat like the Italic letter/, and placed
nearly horizontally at the upper and anterior part of the thorax, immediately
above the first rib. It articulates internally with the upper border of the sternum,
and with the acromion process of the scapula by its outer extremity ; serving to
sustain the upper extremity in the various positions which it assumes, whilst, at
the same time, it allows it great latitude of motion. The horizontal plane of the
clavicle is nearly straight ; but in the vertical plane it presents a double curvature,
the convexity being, in front, at the sternal end; and, behind, at the scapular end.
Its outer third is flattened from above downwards, and extends, in the natural
position of the bone, from the coracoid process to the acromion. Its inner two-
thirds are of a cylindrical form, and extend from the sternum to the coracoid
process of the scapula.
External or Flattened Portion. The outer third is flattened from above down-
wards, so as to present two surfaces, an upper, and a lower ; and two borders, an
anterior, and a posterior.
The upper surface is flattened, rough, marked in front, for the attachment of
the Deltoid ; behind, for the Trapezius ; between these two impressions, externally,
a small portion of the bone is subcutaneous. The under surface is flattened. At
its posterior border, at the junction of the prismatic with the flattened portion, is
a rough eminence, the conoid tubercle ; this, in the natural position of the bone,
surmounts the coracoid process of the scapula, and gives attachment to the conoid
ligament. From this tubercle, an oblique line, occasionally a depression, passes
forwards and outwards to near the outer end of the anterior border ; it is called
the oblique line, and affords attachment to the trapezoid ligament. The anterior
border'is concave, thin, and rough; it limits the attachment of the Deltoid, and
occasionally presents, near 'the centre, a tubercle, the deltoid tubercle, which is
sometimes distinct in the living subject. The posterior border is convex, rough,
broader than the anterior, and gives attachment to the Trapezius.
Internal or Cylindrical Portion. The cylindrical 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.
The anterior border is continuous with the anterior margin of the flat portion.
At its commencement it is smooth, and corresponds to the unoccupied interval
between the attachment of the Pectoralis major and Deltoid muscles ; about the
centre of the clavicle it divides to inclose an elliptical space for the attachment
of the clavicular portion of the Pectoralis major. This space extends inwards as
far as the anterior margin of the sternal extremity.
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 towards the inner third for the attachment
of the Sterno-cleido-mastoid muscle, and terminates at the upper angle of the
eternal extremity.
122
OSTEOLOGY.
The .posterior or subclavian border separates the posterior from the inferior
surface, and extends from the conoid tubercle to the rhomboid depression. It
forms the posterior boundary of the groove for the Subclavius muscle, and gives
attachment to the fascia which incloses it.
The anterior surface is included between the superior and anterior borders. It
is directed forwards and a little upwards at the sternal end, outwards and still
more upwards at the acromial extremity, where it becomes continuous with the
upper surface of the flat portion. Externally, it is smooth, convex, nearly sub-
cutaneous, 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 : an
anterior portion, elliptical in form, rough, and slightly convex, for the attachment
of the Pectoralis major; and an upper part, which is rough behind, for the
attachment of the Sterno-cleido-mastoid. Between the two muscular impressions
is a small subcutaneous interval.
Fi«r. 82. — Left Clavicle. Anterior Surface.
StcTTitilJSxrt^
Acromial HxtJ/
Fig. 83. — Left Clavicle. Inferior Surface.
The posterior or cervical surface is smooth, flat, directed vertically, and looks
backwards towards 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 outwards, and is in relation, by its lower part, with the
suprascapular vessels. It gives attachment, near the sternal extremity, to part of
the Sterno-hyoid muscle ; and presents, at or near the middle, a foramen, directed
obliqiiely outwards, which transmits the chief nutrient artery of the bone. Some-
times, there are two foramina on the posterior surface ; or one on the posterior,
the other 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 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 impression, the
rhomboid, rather more than an inch in length, for the attachment of the costo-
clavicular or rhomboid ligament. The remaining part of this surface is occupied
by a longitudinal groove, the subclavian groove, broad and smooth externally,
SCAPULA. 123
narrow and more uneven internally; it gives attachment to the Subclavius muscle,
ami, by its anterior margin, to the strong aponeurosis which incloses it. Not
untivquently this groove is subdivided into two parts, by a longitudinal line,
which gives attachment to the intermuscular septum of the Subclavius muscle.
The internal or sternal end of the clavicle is triangular in form, directed inwards,
and a little downwards and forwards ; and presents an articular facet, concave
from before backwards, convex from above downwards, 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. This surface is continuous with the costal facet on the inner end of
the inferior or subclavian surface, which articulates with the cartilage of the
first rib.
The outer or acromial extremity, directed outwards and forwards, presents a
small, flattened, oval facet, directed obliquely downwards and inwards, for articu-
lation with the acromion process of the scapula. The direction of this surface
serves to explain the greater frequency of dislocation of this bone upon, and not
beneath, the acromion process. 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 cla-
vicle is generally less curved, smoother, and more slender than in the male. In
those persons who perform considerable manual labor, which brings into constant
action the muscles connected with this bone, it requires considerable bulk, becomes
shorter, and more curved, its ridges for muscular attachment become prominently
marked, and its sternal end of a prismatic or quadrangular form. The right
clavicle is generally heavier, thicker, and rougher, and ofte*n shorter, than the left.
Structure. The shaft, as well as the extremities, consists of cancellous tissue,
invested in a compact layer much thicker in the centre 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
raise its own weight nearly two feet on a level surface ; and sufficient transverse
elastic force, opposite the centre of its anterior convexity, to raise its own weight
about a foot. This extent of elastic power must serve to moderate very consi-
derably the effect of concussions received upon the point of the shoulder.
Development. By two centres : one for the shaft, and one for the sternal extremity.
The centre for the shaft appears very early, before any other bone ; the centre
for the sternal end makes its appearance about the eighteenth or twentieth year,
and unites with the rest of the bone a few years after.
Articulations. With the sternum, scapula, and cartilage of the first rib.
Attachment of Muscles. The Sterno-cleido-mastoid, Trapezius, Pectoralis major,
Deltoid, Subclavius, and Sterno-hyoid.
The Scapula.
The Scapula forms the back part of the shoulder. It is a large flat bone, tri-
angular in shape, situated at the posterior aspect and side of the thorax, between
the first and eighth ribs, its posterior border or base being about an inch from,
and nearly parallel with, the spinous processes of the vertebras. It presents for
examination two surfaces, three borders, and three angles.
The anterior surface or venter (fig. 84) presents a broad concavity, the sub-
scapular fossa. It is marked, in the posterior two-thirds, by several oblique ridges,
which pass from behind obliquely forwards and upwards, the anterior third being
smooth. The oblique ridges, above-mentioned, give attachment to the tendinous
intersections; and the surfaces between them, to the fleshy fibres of the Subscapu-
lars muscle. The anterior third of the fossa, which is smooth, is covered by,
but does not afford attachment to, the fibres of this muscle. This surface is sepa-
rated from the posterior border by a smooth triangular margin at the superior
and inferior angles, and in the interval between these, by a narrow edge which is
124
OSTEOLOGY.
often deficient. This inargin.il surface affords attachment throughout its entire
extent to the Serratus magnus muscle. The subscapular fossa presents a trans-
verse depression at its upper part, called the subscapular angle; it is in this situa-
tion that the fossa is deepest ; and consequently the thickest part of the Sub-
scapularis muscle lies in a line parallel with the glenoid cavity, and must conse-
quently operate most effectively on the humerus which is contained in it.
The posterior surface or dorsum (fig. 85) is arched from above downwards,
alternately convex and concave from side to side. It is subdivided unequally
Fig. 84. — Left Scapula. Anterior Surface or Venter.
into two parts by the spine ; that portion above the spine is caned the supra-
spinous fossa, and that below it, the infra-spinous fossa.
The supraspinous fossa, 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 Supra-spinatus muscle.
The infra-spinous fossa is much larger than the preceding : towards its ver-
tebral margin a shallow concavity is seen at its upper part ; its centre presents a
SCAPULA.
125
prominent convexity, -whilst towards the axillary border is a deep groove, which
runs from the upper towards the lower part. The inner three-fourths of this
surface afford attachment to the Infra-spinatus muscle ; the outer fourth is only
covered 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 part of the
glenoid cavity, downwards and backwards to the posterior border, about an inch
«<»**
Fig. 85. — Left Scapula. Posterior Surface or Dorsum.
Cora co j Qf
above the inferior angle. This ridge serves for the attachment of a strong apon-
eurosis, which separates the Infra-spinatus from the two Teres muscles. The
surface of bone between this line and the axillary border is narrow for the upper
two-thirds of its extent, and traversed near its centre by a groove for the passage
of the dorsalis scapuhe vessels; it affords attachment to the Teres minor. Its
lower third presents a broader, somewhat triangular surface, which gives origin
to the Teres major, and over which glides the Latissimus dorsi ; sometimes the
latter muscle takes its origin by a few fibres from this part. The broad and narrow
126 - OSTEOLOGY.
portions of bone above alluded to are separated by an oblique line, which runs
from the axillary border, downwards and backwards ; to it is attached the aponeu-
rosis separating the two Teres muscles from each other.
The Spine 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-spinous from the infra-spin ous fossa : it commences at the vertebral border
by a smooth triangular surface, over which the Trapezius glides, separated by a
bursa ; and, gradually becoming more elevated as it passes forwards, terminates in the
acromion process which overhangs the shoulder-joint. The spine is triangular and
flattened from above downwards, its apex corresponding to the posterior border ; its
base, which is directed outwards, to the neck of the scapula. It presents two
surfaces and three borders. Its superior surface is concave, assists in forming the
supra-spinous fossa, and affords attachment to part of the Supra-spinatus muscle.
Its inferior surface forms part of the infra-spinous fossa, gives origin to part of the
lnfra-spinatus muscle, and presents near its centre the orifice of a nutritious 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 very rough prominence 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 interval between the lips is also partly covered by the fibres of these muscles.
The external border, the shortest of the three, is slightly concave, its edges thick
and round, continuous above with the under surface of the acromion process ;
below, with the neck of the scapula. The narrow portion of bone external to this
border serves to connect the supra-spinous and infra-spinous fossae.
The Acromion process, so called from forming the summit of the shoulder
(axpov, a summit ; t3,aos, the shoulder), is a large, and somewhat triangular process,
flattened from behind forwards, directed at first a little outwards, and then curving
forwards and upwards, so as to overhang the glenoid cavity. Its upper surface
directed upwards, backwards and outwards, is convex, rough, and gives attachment
to some fibres of the Deltoid. Its under surface is smooth and concave. Its
outer border, which is thick and irregular, affords attachment to the Deltoid
muscle. Its inner margin, shorter than the outer, is concave, gives attachment
to a portion of the Trapezius muscle, and presents about its centre a small oval
surface, for articulation with the scapular 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.
,Of the three borders or costaa of the scapula, the superior is the shortest and
thinnest ; it is concave, terminating at its inner extremity at the superior angle,
at its outer extremity at the coracoid process. At its outer part is a deep
semicircular notch, the supra-scapular, formed partly by the base of the coracoid
process. This notch is converted into a foramen by the transverse ligament, and
serves for the passage of the supra-scapular nerve. The adjacent margin of
the superior border affords attachment to the Omo-hyoid muscle. 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 downwards and backwards to
the inferior angle. Immediately below the glenoid cavity is a rough depression
about an inch in length, which affords attachment to the long head of the Triceps
muscle ; to this succeeds a longitudinal groove, which extends as far as its lower
third, 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 of the Subscapularis in front. The internal or
vertebral border, also named the base, is the longest of the three, and extends
from the superior to the inferior angle of the bone. It is arched, intermediate in
thickness between the superior and the external borders, and that portion of it
above the spine is bent considerably outwards, so as to form an obtuse angle with
SCAPULA. 127
the lower part. The vertebral border presents an anterior lip, a posterior lip, and
an intermediate space. The anterior lip affords attachment to the Serratus mag-
mis ; the posterior lip, to the Supra-spinatus above the spine, the Infra-spinatus
below ; the interval between the two lips, to the Levator anguli scapulas above
the triangular surface at the commencement of the spine ; the Ehomboideus minor,
to the edge of that surface; the Ehomboideus 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.
Of the three angles, the superior, formed by the junction of the superior and
internal borders, is thin, smooth, rounded, somewhat inclined outwards, and gives
attachment to a few fibres of the Levator anguli scapulas muscle. The inferior
angle, thick and rough, is formed by the union of the vertebral and axillary
borders, its outer surface affording attachment to the Teres major, and occasionally
a few fibres of the Latissimus dorsi. The anterior 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 cavity (y^vrj, a superficial
cavity; nSo?, like); its longest diameter is from above downwards, and its
direction outwards and forwards. It is broader below than above ; at its apex is
attached the long tendon of the Biceps muscle. It is covered with cartilage in
the recent state; and its margins, slightly raised, give attachment to a fibro-
cartilaginous structure, the glenoid ligament, by which its cavity is deepened.
The neck of the 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, so called from its fancied resemblance to a crow's beak
(xopat, a crow ; «8os, resemblance), is a thick curved process of bone, which arises by
a broad base from the upper part of the neck of the scapula ; it ascends at first
upwards and inwards ; then, becoming smaller, it changes its direction and passes
forwards and outwards. The ascending portion, flattened from before backwards,
presents in front a smooth concave surface, over which passes the Subscapularis
muscle. The horizontal portion is flattened from above downwards ; its upper
surface is convex and irregular ; its under surface is smooth ; its anterior border
is rough, and gives attachment to the Pectoralis minor ; its posterior border is also
rough for the coraco-acromial ligament, while the apex is embraced by the con-
joined tendon of origin of the short head of the Biceps and Coraco-brachialis
muscles. At the inner side of the root of the coracoid process is a rough depres-
sion for the attachment of the conoid ligament, and, running from it obliquely
forwards and outwards on the upper surface of the horizontal portion, an elevated
ridge for the attachment of the trapezoid ligament.
Structure. In the head, processes, and all the thickened parts of the bone, it
is cellular in structure, of a dense compact tissue in the rest of its extent. The
centre and upper part of the dorsum, but especially the former, is usually so thin
as to be semi-transparent ; occasionally the bone is found wanting in this situation,
and the adjacent muscles come into contact.
Development (fig. 86). By seven centres ; one for the body, two for the coracoid
process, two for the acromion, one for the posterior border, and one for the inferior
angle.
Ossification of the body of the scapula commences about the second month of
fcetal life, by the formation of an irregular quadrilateral plate of bone, imme-
diately 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 the chief part of the scapula is osseous, the coracoid and
acromion processes, the posterior border, and inferior angle, being cartilaginous.
About the first year 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 fifteenth und
128
OSTEOLOGY.
seventeenth years, ossification of the remaining centres takes place in quick suc-
cession, and in the following order : first, near the base of the acromion, and in the
upper part of the coracoid process, the latter appearing in the form of a broad
scale ; secondly, in the inferior angle and contiguous part of the posterior border ;
thirdly, near the extremity of the acromion; fourthly, 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 cases. The two separate nuclei
unite, and then join with the extension carried in 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;
Fig. 86. — Plan of the Development of the Scapula. By Seven Centres.
2 for fc
Kferio*
in some cases of supposed fracture of .the acromion with ligamentous union, it is
probable the detached segment was never united to the rest of the bone.
Articulations. With the humerus and clavicle.
Attachment of Muscles. To the anterior surface, the Subscapularis ; posterior
surface, Supra- spinatus, Infra-spinatus ; spine, Trapezius, Deltoid; superior border,
Omo-hyoid ; vertebral border, Serratus magnus, Levator anguli scapulas, Ehom-
boideus minor and major ; axillary border, Triceps, Teres minor, Teres major ;
glenoid cavity, long head of the Biceps ; coracoid process, short head of Biceps,
Coraco-brach'ialis, Pectoralis minor ; and to the inferior angle, occasionally a few
fibres of the Latissimus dorsi.
HUMERUS. 12?
The Humerus.
The Humerus (fig. 87) is the longest and largest bone of the upper extremity ;
it presents for examination a shaft and two extremities.
The Upper Extremity is the largest part of the bone ; it presents a rounded
head, a constriction around the base of the head, the neck, and two other emi-
nences, the greater and ]esser tuberosities.
The head, nearly hemispherical in form, is directed upwards, inwards, and a
little backwards ; its surface is smooth, coated with cartilage in the recent state,
and articulates with the glenoid cavity of the scapula. 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, and is
called the surgical neck, from its often being the seat of fracture. It should be
remembered, however, that fracture of the anatomical neck does sometimes,
though rarely, occur.
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 narrow groove, separating the head from the
tuberosities. Its circumference affords attachment to the capsular ligament, and
is perforated by numerous vascular foramina.
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 most anterior facet gives attachment to the tendon of
the Supra-spinatus ; the middle one, to the Infra-spinatus ; the posterior one, to
the Teres minor. The outer surface of the great tuberosity is convex, rough,
and continuous with the outer side of the shaft.
The lesser tuberosity is more prominent, although smaller than the greater ; it
is situated in front of the head, and is directed inwards and forwards. Its summit
presents a prominent facet for the insertion of the tendon of the Subscapularis
muscle. The tuberosities are separated from one another by a deep groove, the
bicipital groove, so called from its lodging the long tendon of the Biceps muscle.
It commences above between the two tuberosities, passes obliquely downwards
and a little inwards, and terminates at the junction of the upper with the middle
third of the bone. It is deep and narrow at its commencement, and becomes
shallow and a little broader as it descends. In the recent state it is covered with
a thin layer of cartilage, lined by a prolongation of the synovial membrane of the
shoulder-joint, and receives part of the tendon of insertion of the Latissimus dorsi
about its centre.
The Shaft of the humerus is almost cylindrical in the upper half of its extent ;
prismatic and flattened below, it presents three borders and three surfaces for
examination.
The anterior border runs from the front of the great tuberosity above, to the
coronoid depression below, separating the internal from the external surface. Its
upper part is very prominent and rough; forms the outer lip of the bicipital
groove, and serves for the attachment of the tendon of the Pectoralis major.
About its centre is seen the rough deltoid impression ; below, it is smooth and
rounded, affording attachment to the Brachialis anticus.
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 external head of the Triceps muscle ; its centre is traversed by a broad but
shallow oblique depression, the musculo-spiral groove.; its lower part is marked
by a prominent rough margin, a little curved from behind forwards, which
presents an anterior lip for the attachment of the Supinator longus, above the
Extensor carpi radialis longior below; a posterior lip for the Triceps, and an
interstice for the attachment of the external intermuscular aponeurosis.
L30
OSTEOLOGY.
Fig. 87. — Left Humerus. Anterior View.
Surgical Neck
Common Origin
WFjA
rLEXOft CARPI RADIALI8 WT^m
fAi.MAR18 LONCUS *
FLEXOR nr.lTORUM SUBLIMIS
,, UHH ULNARI*
fflfTroch
8UPINATOB RADII lONCUf
EXTEN30R OARPI RADIALI3
LQNCIQB
.t> Comrn-on Amm
of
y .V EXTENSOR. CARP. BAD. SREV
j& „ DICITOHUM COMMUNIS
., MINIMI DICITI
„ CARPI UlNARIS
iUPikUTQR SREVIS
HUMERUS. 131
The internal border extends from the lesser tuberosity to the internal condyle.
Its upper third is marked by a prominent ridge, forming the inner lip of the
bicipital groove, and gives attachment from above downwards to the tendons of
the Latissimus dorsi, Teres major, and part of the origin of the inner head of the
Triceps. About its centre is a rough ridge for the attachment of the Coraco-
brachialis, and just below this is seen the entrance of the nutritious canal directed
downwards. Sometimes there is a second canal higher up, which takes a similar
direction. Its inferior third is raised into a slight ridge, which becomes very
prominent below; it presents an anterior lip for the attachment of the Brachialis
anticus, a posterior lip for the internal head of the Triceps, and an intermediate
space for the internal intermuscular aponeurosis.
The external surface is directed outwards above, where it is smooth, rounded,
and covered by the Deltoid muscle ; forwards below, where it is slightly concave
from above downwards, 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 Deltoid muscle, and below it the musculo-spiral groove, directed
obliquely from behind, forwards and downwards ; it transmits the musculo-spiral
nerve and superior profunda artery.
The internal surface, less extensive than the external, is directed forwards
above, forwards and inwards below ; at its upper part it is narrow, and forms the
bicipital groove. The middle part of this surface is slightly rough for the
attachment of the Coraco-brachialis ; its lower part is smooth, concave, and gives
attachment to the Brachialis anticus muscle.1
The "posterior surface (fig. 88) appears somewhat twisted, so that its upper part
is directed a little inwards, its lower part backwards, and a little outwards.
Nearly the whole of this surface is covered by the external and internal heads of
the Triceps, the former being attached to its upper and outer part, the latter to
its inner and back part, their origin being separated by the musculo-spiral groove.
The Lower Extremity is flattened from before backwards, and curved slightly
forwards : it terminates below in a broad articular surface, which is divided into
two parts by a slight ridge. On either side of the articular surface are the ex-
ternal and internal condyles. The articular surface extends a little lower than
the condyles, and is curved slightly forwards, 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 lesser or radial head of the humerus ;
it articulates with the cup-shaped depression on the head of the radius, 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. The
inner or trochlear portion of the articular surface presents a deep depression
between two well-marked borders. This surface is convex from before back-
wards, 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
1 A small hook-shaped process of bone, varying from T'ff to $ of an inch in length, is not
unfrequently found projecting from the inner surface of the shaft of the humerus two inches
above the internal condyle. It is curved downwards, forwards, and inwards, and its pointed
extremity is connected to the internal border just above the inner condyle, by a ligament or
fibrous band; completing an arch, through which 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 accompanied by the ulnar interosseous 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 supra-condyloid 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.
132
OSTEOLOGY.
Fie;. 88. — Left Humerus. Posterior Surface.
1 9
e
f*
[Jrochi
to tlie interval between the radius and
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 ca-
vity of the ulna ; it is broader and deeper
on the posterior than on the anterior aspect
of the bone, and is directed obliquely from
behind forwards, and from without in-
wards. Above the back part of the
trochlear surface, is a deep triangular de-
pression, the olecranon depression in which
is received the summit of the olecranon
process in extension of the forearm. Above
the front part of the trochlear surface, is
seen a small depression, the coronoid de-
pression ; it receives the coronoid process
of the ulna during flexion of the fore-
arm. These fossae are separated from one
another by a thin transparent laminae of
bone, which is sometimes perforated; their
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 articula-
tion. Above the front part of the radial
tuberosity, is seen a slight depression
which receives the anterior border of the
head of the radius when the forearm is
strongly flexed. The external condyle
is a small tubercular eminence, less pro-
minent than the internal, curved a little
forwards, 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 supi-
nator muscles. The internal condyle,
larger and more prominent than the ex-
ternal, is directed a little backwards, and
gives attachment to the internal lateral
ligament, and to a tendon common to the
origin of some of the flexor muscles of
the forearm. These eminences are di-
rectly continuous above with the external
and internal borders. The greater pro-
minence of the inner one renders it more
liable to fracture.
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.
Development, By seven centres (fig.
89): one for the shaft, one for the head,
HUMERUS.
133
Fig. 89. — Plan of the Development of the
Humerus. By 7 Centres.
Epiphyses ef Head fcj A*
Tuberosities blrml at\<*j
S.Uranil unite \
*>i'L& SAaft at 2U 4*y '. J
one for the greater tuberosity, one for the radial portion of the articular surface,
one for the trochlear portion, and one for each condyle. The centre for the shaft
appears very early, soon after ossification has commenced in the clavicle, and
soon extends towards the extremities. At birth, it is ossified nearly in its whole
length, the extremities remaining cartilaginous. Between the first and second
years, ossification commences in the head of the bone, and between the second
and third years the centre for the tuberosities makes its appearance usually by a
single ossific point, but sometimes, according to Beclard, by one for each tube-
rosity, that for the lesser being small, and not appearing until after the fourth
year. By the fifth year, the centres for the head and tuberosities have enlarged
and become 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 radial portion of the articular sur-
face, and from this point extends inwards,
so as to form the chief part of the articular
end of the bone, the centre for the inner
part of the articular surface 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 between the thirteenth or fourteenth
year. About the sixteenth or seventeenth
year, the outer condyle and both portions
of the articulating surface, having already
joined, unite with the shaft ; at eighteen
years, the inner condyle becomes joined,
whilst 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 Muscles. To the greater
tuberosity, the Supra-spinatus, Infraspina-
tus, and Teres minor ; to the lesser tube-
rosity, the Subscapularis ; to the anterior
bicipital ridge, the Pectoralis major; to the
posterior bicipital ridge and groove, the
Latissimus dorsi and Teres major ; to the
shaft, the Deltoid, Coraco-brachialis, Bra-
chialis 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 digitorum sublimis,
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 brevior, Extensor communis digitorum, Extensor
minimi digiti, and Extensor carpi ulnaris, the Anconeus, and Supinator brevis.
TTnites with.
Shaftat
18*
'*' )A
THE FOREARM.
The Forearm is that portion of the upper extremity, situated between the elbow
and wrist. It is composed of two bones, the Ulna, and the Radius.
The Ulna.
The Ulna (figs. 90 and 91), so called from its forming the elbow {iumfo is a long
bone, prismatic in form, placed at the inner 6ide of the forearm, parallel with the
134
OSTEOLOGY.
Fig. 90. — Bones of the Left Forearm. Anterior Surface.
ULNA
i * T <*
ME „,-,/■'«
RADIUS
fJXKOR DICITORUM
SUBLIMIS
PRONATOR
RAOII. TERES
accairicrn/iZ origi
tf FLEXOR IONCUS POLL1CIS
RadiuZ Oriain
FLEXOR DICITORUM
SUBLIMIS
Styloid Process ^
SUPINATOR LONCU»
Grooix for ext. ossis
METACARPI FOLLIC/5
GrceivfinEKT. PR1MI
ERNOOII POLLICIS
/Styloid J.'rJcess
ULNA. 135
radius, being the largest and longest of the two. 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 downwards, 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.
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.
The Olecranon Process (<Z\(vrj, elbow; x\>dvov, head) is a large, thick, curved
eminence, situated at the upper and back part of the ulna. It rises somewhat
higher than the coronoid, is curved forwards at the summit so as to present a pro-
minent tip, 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. Its posterior surface, directed backwards, is of a triangular form,
smooth, subcutaneous, and covered by a bursa. Its upper surface, directed
upwards, 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 anterior surface 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 interior lateral ligament internally ; the posterior liga-
ment externally. The olecranon process, in its structure as well as in its position
and use, resembles the Patella in the lower limb ; and, like it, sometimes exists
as a separate piece, not united to the rest of the bone.1
The Coronoid Process (xopAvt], a crow's beak; n'So$, form) is a rough triangular
eminence of bone which projects horizontally forwards from the upper and front
part of the ulna, forming the lower part of the great sigmoid cavity. Its base is
continuous 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 upwards,
and 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 great sigmoid
cavity. The under surface is concave, and marked internally by a rough impression
for the insertion of the Brachialis anticus. At the junction of this surface with
the shaft is a rough eminence, the tubercle of the ulna, for the attachment of the
oblique ligament. 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 digitorum sublimis. 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.
The Greater Sigmoid Cavity (olyna, fJSoj, form), so called from its resemblance
to the Greek letter x, is a semilunar depression of large size, situated between 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 downwards,
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 largest ; it is slightly concave transversely, the external
portion being nearly plane from side to side.
1 Professor Owen regards the olecranon to be homologous not with the patella, but with an
extension of the upper end of the fibula above the knee-joint, which is met with in the Ornitho-
rynchus, Echidna, and some other animals. (Owen, " On the Nature of Limbs.")
136 OSTEOLOGY.
The Lesser Sigmoid Cavity is a narrow, oblong, articular depression, placed on
the outer side of the coronoid process, and serving for articulation with the head
of the radius. It is concave from before backwards ; and its extremities, which
are prominent, serve for the attachment of the orbicular ligament.
The Shaft is prismatic in form at its upper part, and curved from behind for-
wards, and from within outwards, so as to be convex behind and externally ; its
central part is quite straight ; its lower part rounded, smooth, and bent a little
outwards ; it tapers gradually from above downwards, and presents for examina-
tion three borders, and three surfaces.
The anterior border commences above at the prominent inner angle of the coro-
noid 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 : sharp and prominent in its lower
fourth for the attachment of the Pronator quadratus. It separates the anterior
from the internal surface.
The posterior border commences above at the apex of the triangular 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 an
aponeurosis common to the Flexor carpi ulnaris, the Extensor carpi ulnaris, and
the Flexor profundus digitorum muscles ; its lower fourth is smooth and rounded.
This border separates the internal from the posterior surface.
The external border commences above by two lines, which converge one from
each extremity of the lesser sigmoid cavity, inclosing between them a triangular
space for the attachment of part of the Supinator brevis, and terminates below at
the middle of the head of the ulna. Its two middle fourths are very prominent,
and serve for the attachment of the interosseous membrane ; its lower fourth is
smooth and rounded. This border separates the anterior from the posterior surface.
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 digi-
torum; its lower fourth, also concave, to the Pronator quadratus. The lower
fourth is separated from the remaining portion of the bone by a prominent ridge,
directed obliquely from above downwards and inwards ; this ridge marks the
extent of attachment of the Pronator above. At the junction of the upper with
the middle third of the bone, is the nutritious canal, directed obliquely upwards
and inwards.
The posterior surface, directed backwards and outwards, 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, downwards to the posterior
border ; the triangular surface above this ridge receives the insertion of the An-
coneus muscle, whilst the ridge itself affords attachment to the Supinator brevis.
The surface of bone below this is subdivided by a longitudinal ridge into two
parts ; the internal part is smooth, concave, and gives origin to, occasionally is
merely covered by, the Extensor carpi ulnaris. The external portion, wider and
rougher, gives attachment from above downwards to part of the Supinator brevis,
the Extensor ossis metacarpi pollicis, the Extensor secundi internodii pollicis, and
the Extensor indicis muscles.
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 Lower Extremity of the ulna is of small size, and excluded from the articu-
lation of the wrist-joint. It presents for examination two eminences ; the outer
and larger is a rounded articular eminence, termed the head of the ulna. The
inner, narrower and more projecting, is a non- articular eminence, the styloid
process. The head presents an articular facet, part of which, of an oval form, is
directed downwards, and plays on the surface of the triangular fibro-cartilage,
which separates this bone from the wrist-joint ; the remaining portion, directed
ULNA.
137
Fig. 91. — Bones of the Left Forearm. Posterior Surface.
ULNA
RADIUS
for £XT. CARFI RAD.LONC.
EXT. CARD RAD.BKEVIOR
EXT. StCUNDI INTERNOOII POLLIC1*
LfXOR TJiaiTOnUM
SUSLIMIS
firr CXT. CARPI ULNAR.
[' EXT. INDICII
ft/'ri tvr. DICITORUM COMMUNIS
[ »~T. MINIMI DIGIT!
138
OSTEOLOGY,
Fi
92. — Plan of the Development of the Ulna.
By 3 Centres.
Olec ran&n
Agpca rs at 10^^-f^^^JointS'Jiafc ac /(>.'? y*
outwards, is narrow, convex, and received into the sigmoid cavity of the radius.
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 separated
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 extremity,
and one for the olecranon (fig. 92). Ossification commences near the middle of
the shaft about the fifth 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 pro-
cess. 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 sixteenth 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 the olecra-
non : the Triceps, Anconeus, and one head
of the Flexor carpi ulnaris. To the coro-
noid process; the Brachialis anticus, Pro-
nator radii teres, Flexor sublimis digito-
rum, and Flexor profundus digitorum. To
the shaft: the Flexor profundus digitorum,
Pronator quadratus, Flexor carpi ulnaris,
Extensor carpi ulnaris, Anconeus, Supi-
nator brevis, Extensor ossis metacarpi
pollicis, Extensor secundi internodii polli-
cis, and Extensor indicis.
Appear? at 4 3f# {j3fS-J»itU Slmft at ZOtl ■;*
°^Har
«**'
The Eadius.
The Radius, so called from its fancied resemblance to the spoke of a wheel, is
situated on the outer side of the forearm, lying parallel with the ulna, which
exceeds it in length and size. 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, having a prismatic form, slightly curved
longitudinally, and presenting for examination a shaft and two extremities.
The Upper Extremity presents a head, neck, and tuberosity. The' head is of
a cylindrical form, depressed on its upper surface into a shallow cup, which
articulates with the radial or lesser head of the humerus in flexion of the .joint.
Around the circumference of the head is a smooth articular surface, coated with
cartilage in the recent state, broad internally where it rotates within the lesser
sigmoid cavity of the ulna, narrow in the rest of its circumference, to play in the
orbicular ligament. The head is supported on a round, smooth, and constricted
portion of bone, called the neck, 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 tuberosity. Its surface is
divided into two parts by a vertical line ; a posterior rough portion, for the
RADIUS. 139
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 of the bone is prismoid in form, narrower above than below, and
slightly curved, so as to be convex outwards. It presents three surfaces, separated
by three borders.
The anterior border extends from the lower part of the tifberosity 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, downwards and outwards, has received the name of the oblique
line of the radius. It gives attachment, externally, to the Supinator brevis;
internally, to the Flexor longus pollicis, and between these to the Flexor digito-
rum sublimis. The middle third of the anterior border is indistinct and rounded.
Its lower fourth is sharp, prominent, affords attachment to the Pronator quadra-
tus, and terminates in a small tubercle, into which is inserted the tendon of the
Supinator longus.
The posterior border commences above, at the back part of the neck of the
radius, and terminates below, at the posterior part of the base of the styloid pro-
cess ; it separates the posterior from the external surface. It is indistinct above
and below, but well marked in the middle third of the bone.
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 bifurcates into two ridges, which descend to the
anterior and posterior margins of the sigmoid cavity. This border separates the
anterior from the posterior surface, and has the interosseous membrane attached
to it throughout the greater part of its extent.
The anterior surface is narrow and concave for its upper two-thirds, and gives
attachment to the Flexor longus pollicis muscle ; below, it is broad and flat, and
gives attachment to the Pronator quadratus. At the junction of the upper and
middle thirds of this surface is the nutritious foramen, which is directed obliquely
upwards.
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 primi internodii pollicis 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.
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 Pronator radii teres muscle. Its
lower part is narrow, and covered by the tendons of the Extensor ossis metacarpi
pollicis and Extensor primi internodii pollicis muscles.
The Lower extremity of the radius is large, of quadrilateral 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 is of triangular form, concave, smooth, and divided by a slight
antero-posterior ridge into two parts. Of these, the external is large, of a trian-
gular form, and articulates with the scaphoid bone; the inner, smaller and
quadrilateral, articulates with the semilunar. The articular surface for the ulna
is called the sigmoid cavity of the radius; 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 down-
wards into a strong conical projection, the styloid process, which gives attachment
by its base to the tendon of the Supinator longus, and by its apex to the external
lateral ligament of the wrist-joint. The outer surface of this process is marked
by two grooves, which run obliquely downwards and forwards, and are separated
140
OSTEOLOGY.
Fig. 93. — Plan of the Development of the Radius.
By 3 Centres.
Aj>Dta.rs at Jt*y--
JTeatf
)-:lfruttll it-ith Shaft aba
puberty
from one another by an elevated ridge. The most anterior one gives passage to
the tendon of the Extensor ossis metacarpi pollicis, the posterior one to the tendon
of the Extensor primi internodii pollicis. The posterior surface is convex, affords
attachment to the posterior ligament of the wrist, and is marked by three grooves.
The most external is broad, but shallow, and subdivided into two by a slightly
elevated ridge. The external groove transmits the tendon of the Extensor carpi
radialis longior, the inner one the tendon of the Extensor carpi radialis brevior,
Near the centre of the bone is a deep, but narrow, groove, directed obliquely from
above downwards and outwards; it transmits the tendon of the Extensor secundi
internodii pollicis. Internally is a broad groove, for the passage of the tendons of
the Extensor communis digitorum, and Extensor indicis ; the tendon of the Extensor
minimi digiti passing through the groove at its point of articulation with the ulna.
Structure. Similar to that of the other long bones.
Development (fig. 93). 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, soon after the development of
the humerus commences. At birth,
the shaft is ossified ; but the ends of
the bone are cartilaginous. About the
end of the second year, ossification
commences in the lower epiphysis;
and about the fifth year, in the upper
one. At the age of puberty, the up-
per epiphysis becomes joined to the
shaft; the lower epiphysis becoming
united about the twentieth year.
Articulations. With four bones; the
humerus, ulna, scaphoid, and semi-
lunar.
Attachment of Muscles. To the tu-
berosity, the Biceps ; to the oblique
ridge, the Supinator brevis, Flexor
digitorum sublimis, and Flexor longus
pollicis ; to the shaft — its anterior sur-
face, the Flexor longus pollicis and
Pronator quadratus ; its posterior sur-
face, the Extensor ossis metacarpi
pollicis, and Extensor primi internodii
pollicis; its outer surface, the Pro-
nator radii teres; and to the styloid
process, the Supinator longus.
feaw
Appears at Zv^-yH
\ "Unites with. SAa ft al.t
.fcxtrcmi
THE HAND.
The Hand is subdivided into three segments, the Carpus or wrist, the Meta-
carpus or palm, and the Phalanges or fingers.
Carpus.
The bones of the Carpus, 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, magnum, and unciform.
Common Characters of the Carpal Bones.
Each bone (excepting the pisiform) presents six surfaces. Of these, the ante-
rior or palmar, and the posterior or dorsal, are rough, for ligamentous attachment,
CARPUS. 141
the dorsal surface being generally the broadest of the two. The superior and
inferior are articular, the superior generally convex, the inferior concave ; and
the internal and external are also articular when in contact with contiguous
bones, otherwise rough and tubercular. Their structure in all is similar, con-
sisting within of cancellous tissue inclosed in a layer of compact bone. Each
bone is also developed from a single centre of ossification.
Bones of the Upper Row. (Figs. 94 and 95.)
The Scaphoid is the largest bone of the first 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 the upper and outer part of the carpus,
its direction being from above downwards, outwards, and forwards. Its superior
surface is convex, smooth, of triangular shape, and articulates with the lower end
of the radius. Its inferior surface, directed downwards, outwards, and backwards,
is smooth, convex, and triangular, and divided by a slight ridge into two parts,
the external of which articulates with the trapezium, the inner with the trapezoid.
Its posterior or dorsal surface presents a narrow, rough groove, which runs the
entire breadth 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 tubercle, which projects forwards from the front
of the carpus, and gives attachment to the anterior annular ligament of the wrist.
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 bone; the inferior or larger is concave, forming, with the
semilunar bone, a concavity for the head of the os magnum.
To ascertain to which hand this bone belongs, hold the convex radial articular
surface upwards, and the dorsal surface backwards ; the prominent tubercle will
be directed to the side to which the bone belongs.
Articulations. With five bones ; the radius above, trapezium and trapezoid
below, os magnum and semilunar internally.
The Semilunar bone may be distinguished by its deep concavity and crescentic
outline. It is situated in the centre of the upper range of the carpus, between
the scaphoid and cuneiform. Its superior surface, convex, smooth, and quadrilateral
in form, articulates with the radius. Its inferior surface is deeply concave, and
of greater extent from before backwards, 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. Its anterior or palmar and posterior
or dorsal surfaces are rough, for the attachment of ligaments, the former being the
broader, and of somewhat rounded form. The external surface presents a narrow,
flattened, semilunar facet, for articulation with the scaphoid. The internal surface
is marked by a smooth, quadrilateral facet, for articulation with the cuneiform.
To ascertain to which hand this bone belongs, hold it with the dorsal surface
upwards, and the convex articular surface backwards ; the quadrilateral articular
facet will then point to 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.
The Cuneiform (VOs Pyramidal) may be distinguished by its pyramidal shape,
and from having an oval-shaped, isolated facet, for articulation with the pisiform
bone. It is situated at the upper and inner side of the carpus. The superior
surface presents an internal, rough, non-articular portion; and an external or
articular portion, which is convex, smooth, and separated from the lower end of
the ulna by the interarticular fibro-cartilage of the wrist. The inferior surface,
directed outwards, is concave, sinuously curved, and smooth, for articulation with
the unciform. Its posterior or dorsal surface is rough, for the attachment of liga-
ments. Its anterior or palmar surface presents, at its inner side, an oval-shaped
142
OSTEOLOGY.
facet, for articulation with the pisiform ; and. is rough externally, for ligamentous
attachment. Its external 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
of the internal lateral ligament of the wrist.
Fig. 94. — Bones of the Left Hand. Dorsal Surface.
""■"""•iDM
l,s snviog
Metacarpus
,XT- MUM,
mTERMoo„
Phalange*
1U Row
Z^Row
Tr?M0Ufi
CARPUS. 143
To ascertain to which hand this bone belongs, hold it so that the base is
directed backwards, and the articular facet for the pisiform bone upwards ; the
concave articular facet will point to the side to which the bone 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.
The Pisiform bone may be known by its small size, and from its presenting a
single articular facet. It is situated at the anterior and inner side of the carpus,
is nearly circular in form, and presents on its posterior surface a smooth, oval
facet, for articulation with the cuneiform bone. This facet approaches the supe-
rior, but not the inferior, border of the bone! Its anterior or palmar surface is
rounded and rough, and gives attachment to the anterior annular ligament. The
outer and inner surfaces are also rough, the former being convex, the latter usually
concave.
To ascertain to which hand it belongs, hold the bone with its posterior or artic-
ular facet downwards, and the non-articular portion of the same surface back-
wards ; the inner concave surface will then point to the side to which the bone
belongs.
Articulations. With one bone, the cuneiform.
Attachment of Muscles. To two : the Flexor carpi ulnaris, and Abductor minimi
digiti ; and to the anterior annular ligament.
Bones of the Lower Row. (Figs. 94 and 95.)
The Trapezium is of very irregular form. It may be distinguished by a deep
groove, for 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 meta-
carpal bone. The superior surface, concave and smooth, is directed upwards and
inwards, and articulates with the scaphoid. Its inferior surface, directed down-
wards and outwards, is oval, concave from side to side, convex from before back-
wards, 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 downwards and
inwards; it transmits the tendon of the Flexor carpi radialis, and is bounded
externally by a prominent ridge, the oblique ridge of the trapezium. This sur-
face gives attachment to the Abductor pollicis, Flexor ossis metacarpi, and Flexor
brevis pollicis muscles; and the anterior annular ligament. The posterior or
dorsal surface is rough, and the external surface also broad and rough, for the
attachment of ligaments. The internal surface presents two articular facets ; the
upper one, large and concave, articulates with the trapezoid; the lower one,
narrow and flattened, with the base of the second metacarpal bone.
To ascertain to which hand it belongs, hold the bone with the grooved palmar
surface upwards, and the external, broad, non-articular surface backwards; the
saddle-shaped surface will then be directed 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, part of the
Flexor brevis pollicis, and the anterior annular ligament.
The Trapezoid is the smallest bone in the second row. It may be known by
its wedge-shaped form ; its broad end occupying the dorsal, its narrow end the
palmar surface of the hand. Its superior surface, quadrilateral in form, smooth
and slightly concave, articulates with the scaphoid. The inferior surface articu-
lates with the upper end of the second metacarpal bone ; it is convex from side to
side, concave from before backwards, and subdivided, by an elevated ridge, into
two unequal lateral facets. The posterior or dorsal, and anterior or palmar
surfaces are rough, for the attachment of ligaments ; the former being the larger
of the two. The external surface, convex and smooth, articulates with the
144
OSTEOLOGY.
trapezium. The internal surface is concave and smooth below, for articulation
with the os magnum ; rough above, for the attachment of an interosseous ligament.
Fig. 95. — Bones of the Left Hand. Palmar Surface.
Ccorjms
FLEXOR. CARPi ULNARIS
FLEXOR BREVtS MINIMI DICIT
fLEXOR OSSIS METACARPI
MINIMI DICITl
h"'' ...»
MrfMcar/iiLS
Dp„ofU"ou8
CARPUS. 145
To ascertain to which side this bone belongs, let the broad dorsal surface be
held upwards, and its inferior concavo-convex surface forwards; the internal
concave surface will then point to the side to which the bone belongs.
Articulations. With four bones : the scaphoid above, second metacarpal bone
below, trapezium externally, os magnum internally.
Attachment of Muscks. Part of the Flexor brevis pollicis.
The Os Magnum is the largest bone of the carpus, and occupies the centre of
the wrist. It presents, above, a rounded 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. Its superior surface is rounded, smooth, and
articulates with the semilunar. Its 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 ; and the anterior or palmar, narrow, rounded,
but also rough, for the attachment of ligaments. 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 unciform
by a smooth, concave, oblong facet, which occupies its posterior and superior
parts ; rough in front, for the attachment of an interosseous ligament.
To ascertain to which hand this bone belongs, the rounded head should be held
upwards, and the broad dorsal surface forwards ; the internal concave articular
surface will point to its appropriate side.
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 Flexor brevis pollicis.
The Unciform bone 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 and lower angle of the carpus, with its base downwards, resting on the two
inner metacarpal bones, and its apex directed upwards and outwards. Its superior
surface, the apex of the wedge, is narrow, convex, smooth, and articulates with
the semilunar. Its inferior surface articulates with the fourth and fifth meta-
carpal bones, the concave surface for each being separated by a ridge, which runs
from before backwards. 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 process of bone, the unciform process, directed
from the palmar surface forwards and outwards. It gives attachment, by its
apex, to the annular ligament ; by its inner surface, to the Flexor brevis minimi
digiti, and the Flexor ossis metacarpi 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 surface, cut obliquely from
above downwards and inwards. Its external surface articulates with the os mag-
num by its upper and posterior part, the remaining portion being rough, for the
attachment of ligaments.
To ascertain to which hand it belongs, hold the apex of the bone upward^ and
the broad dorsal surface backwards ; the concavity of the unciform process will
be directed to the side to which the bone belongs.
Articulations. With five bones : the semilunar above, the fourth and fifth meta-
carpal below, the cuneiform internally, the os magnum externally.
Attachment of Muscles. To two : the Flexor brevis minimi digiti, and the
Flexor ossis metacarpi minimi digiti ; and to the anterior annular ligament.
10
146 OSTEOLOGY.
The Metacaepus.
The Metacarpal bones are five in number : they are long cylindrical bones,
presenting for examination a shaft, and two extremities.
Common Chaeactees of the Metacaepal Bones.
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 lateral surfaces are concave, for the attach-
ment of the Interossei muscles, and separated from one another by a prominent
line. The posterior or dorsal surface is triangular, smooth, and flattened below,
and covered, in the recent state, by the tendons of the extensor muscles. In its
upper half, it is divided by a ridge into two narrow lateral depressions, for the
attachment of the Dorsal interossei muscles. This ridge bifurcates a little above
the centre of the bone, and its branches run to the small tubercle on each side of
the digital extremity.
The carpal extremity or base is of a cuboidal form, and broader behind thnn in
front: it articulates, above, with the carpus; and,' on each side, with the adjoining
metacarpal bones ; its dorsal and palmar surfaces being rough, for the attachment
of tendons and ligaments.
The digital extremity or head presents an oblong surface, flattened at each
side, for articulation with the first phalanx; it is broader and extends farther
forwards in front than behind ; and is longer in the antero-posterior than in the
transverse diameter. On either side of the head is a deep depression, surmounted
by a tubercle, for the attachment of the lateral ligament of the metacarpophalan-
geal joint. The posterior surface, broad and flat, supports the Extensor tendons ;
and the anterior surface presents a median groove, bounded on each side by a
tubercle, for the passage of the Flexor tendons.
Peculiae Metacaepal Bones.
The metacarpal bone of the thumb is shorter and wider than the rest, diverges
to a greater degree from the carpus, and its palmar surface is directed inwards
towards the palm. The shaft is flattened and broad on its dorsal aspect, and does
not present the bifurcated ridge peculiar to the other metacarpal bones ; concave
from before backwards on its palmar surface. The carpal extremity or base
presents a concavo-convex surface, for articulation with the trapezium, and has no
lateral facets. The digital extremity is less convex than that of the other metacarpal
bones, broader from side to side than from before backwards, and terminates anteri-
orly in a small articular eminence on each side, over which play two sesamoid bones.
The metacarpal bone of the index finger is the longest, and its base the largest of
the other four. Its carpal extremity is prolonged upwards and inwards ; and its
dorsal and palmar surfaces are rough, for the attachment of tendons and ligaments.
It presents four articular facets: one at the end of the bone, which has an angular
depression, for articulation with the trapezoid ; on the radial side, a flat quadri-
lateral facet, for articulation with the trapezium ; its ulnar side being prolonged
upwards and inwards, to articulate, above, with the os magnum ; internally, with
the third metacarpal bone.
The metacarpal bone of the middle finger is a little smaller than the preceding ;
it presents a pyramidal eminence on the radial side of its base (dorsal aspect), which
extends upwards behind the os magnum. The carpal articular facet is concave be-
hind, flat and horizontal in front, and corresponds to 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 articulation with the f jurth metacarpal.
The metacarpal bone of the ring finger is shorter and smaller than the pre-
ceding, and its base small and quadrilateral, its carpal surface presenting two
facets, for articulation with the unciform and 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.
METACARPUS AND PHALANGES. 147
The metacarpal bone of the little finger may be distinguished by the concavo-
convex form of its carpal surface, for articulation with the unciform, and from
having only one lateral articular facet, which corresponds with the fourth meta-
carpal 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.
Articulations. The first, with the trapezium ; the second, with the trapezium,
trapezoides, os magnum, and third metacarpal bones ; the third, with the os mag-
num, 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.
Attachment of Muscles. To the metacarpal bone of the thumb, three : the Flexor
ossis metacarpi pollicis, Extensor ossis metacarpi pollicis, and first Dorsal inter-
osseous. To the second metacarpal bone, five : the Flexor carpi radialis, Extensor
carpi radialis longior, first and second Dorsal interosseous, and first Palmar inter-
osseous. To the third, five : the Extensor carpi radialis brevior, Flexor brevis
pollicis, Adductor pollicis, and second and third Dorsal interosseous. To the
fourth, three : the third and fourth Dorsal interosseous and second Palmar. To
the fifth, four : the Extensor carpi ulnaris, Flexor carpi ulnaris, Flexor ossis
metacarpi minimi digiti, and third Dorsal interosseous.
Phalanges.
The Phalanges are the bones of the fingers ; they are fourteen in number, three
for each finger and two for the thumb. They are long bones, and present for
examination a shaft, and two extremities. The shaft tapers from above down-
wards, is convex posteriorly, concave in front from above downwards, flat from
side to side, and marked laterally by rough ridges, which give attachment to the
fibrous sheaths of the Flexor tendons. The metacarpal extremity or base, in the
first row, presents an oval concave articular surface, broader from side to side,
than from before backwards ; and the same extremity in the other two rows, a
double concavity separated by a longitudinal median ridge, extending from before
backwards. The digital extremities are smaller than the others, and terminate,
in the first and second row, in two small lateral condyles, separated by a slight
groove, the articular surface being prolonged farther forwards on the palmar than
on the dorsal surface, especially in the first row.
The Ungual phalanges are convex on their dorsal, flat on their palmar surfaces;
they are recognized by their small size, and from their ungual extremity presenting,
on its palmar aspect, a roughened elevated surface of a horseshoe form, 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, four
muscles : the Extensor primi internodii pollicis, Flexor brevis pollicis, Abductor
pollicis, Adductor pollicis. To the second phalanx, two : the Flexor longus pollicis,
and the Extensor secundi internodii. 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 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 Flexor sublimis digitorum, Extensor com-
munis 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.
148
OSTEOLOGY.
Development of the Hand.
The Carpal hones are each developed by a single centre; at birth they are all
cartilaginous. Ossification proceeds in the following order (fig. 96): 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.
Fig. 96. — Plan of the Development of the Hand.
Carpus
1 cent re jo reach bone
Ml cartilaginous at lirtJt
Metacarpus
2 Centres for euch bone
■Ifor Shaft
i for Digital Extremity
except 1-4
Phalanges
2 Centres for each lone
t for Shaft
1 for Metacarpal L'xt*.
ap/i.fr-O'f'yr
untie f8-Z0^'y^
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
respect, resembles the phalanges. Ossification commences in the centre of the
shaft about the sixth 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, commence to ossify, and they unite about the
twentieth year.
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
sixth 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 row. The two
centres become united, in each row, between the eighteenth and twentieth years.
OS INNOMINATUM. 149
OF THE LOWER EXTREMITY.
The Lower Extremity consists of three segments, the thigh, leg, snadfoot, which
correspond to the arm, forearm, and hand in the upper extremity. It is connected
to the trunk through the os innominatum or haunch, which is homologous with
the shoulder.
The Os Innominatum.
The Os Innominatum or nameless bone, so called from bearing no resemblance
to any known object, is a large irregular-shaped bone, which, with its fellow of
the opposite side, 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, situated near the middle of the outer side 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 pubes.
The ilium, so called from its supporting the flank (ilia), is the superior broad
and expanded portion which runs upwards from the upper and back part of the
acetabulum, and forms the prominence of the hip.
The ischium (lax^, the hip) is the inferior and strongest portion of the bone ;
it proceeds downwards from the acetabulum, expands into a large tuberosity, and
then, curving upwards, forms with the descending ramus of the pubes a large
aperture, the obturator foramen.
The pubes is that portion which runs horizontally inwards from the inner side
of the acetabulum for about two inches, then makes a sudden bend, and descends
to the same extent ; it forms the front of the pelvis, supports the external organs
of generation, and has received its name from being covered with hair.
The Ilium presents for examination two surfaces, an external and an internal,
a crest, and two borders, an anterior and a posterior.
External Surface or Dorsum of the Ilium (fig. 97). The back part of this sur-
face is directed backwards, downwards, and outwards ; its front part forwards,
downwards and outwards. It is smooth, convex in front, deeply concave behind;
bounded above by the crest, 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, the shortest of the three, com-
mences at the crest, about two inches in front of its posterior extremity ; it is at
first distinctly marked, but as it passes downwards and outwards to the upper
part of the great sacro-sciatic notch, where it terminates, it becomes less marked,
and is often altogether lost. The rough surface included between this line and
the crest, affords attachment to part of the Gluteus maximus above, a few fibres
of the Pyriformis below. The middle curved line, the longest of the three, com-
mences at the crest, about an inch behind its anterior extremity, and, taking a
curved direction downwards and backwards, terminates at the upper part of the
great sacro-sciatic notch. The space between the middle and superior 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
nutritious foramen. The inferior curved line, the least distinct of the three, com-
mences in front at the upper part of the anterior inferior spinous process, and
taking a curved direction backwards and downwards, terminates at the anterior
part of the great sacro-sciatic notch. The surface of bone included between the
middle and inferior curved lines is concave from above downwards, convex from
before backwards, and affords attachment to the Gluteus minimus muscle. Beneath
the inferior curved line, and corresponding to the upper part of the acetabulum,
is a smooth eminence, sometimes a depression, to which is attached the reflected
tendon of the Rectus femoris muscle.
The Internal Surface (fig. 98) of the ilium is bounded above by the crest,
below by a prominent line, the linea ilio-pectinea, and before and behind by the
150
OSTEOLOGY.
anterior and posterior borders. It presents anteriorly a large smooth concave
surface called the internal iliac fossa or venter of the ilium ; it lodges the Iliacus
muscle, and presents at its lower part the orifice of a nutritious canal. Behind
the iliac fossa is a rough surface, divided into two portions, a superior and an
Fig. 97. — Right Os Innominatum. External Surface.
Anfrriom
prruir
Iho-pirtttua I Lin* for
GimbtT nat't Lie T.
CEMELL.U3 SUPERIOR
fifint. of Sick,
CEREU.US IN TEH 10
Spine of Fulirs
for Fat/parti lic anient
.ArujlitfPubts
cctus abuomimi*
ctumioams
inferior. The inferior or auricular portion, so called from its resemblance to the
external ear, is coated with cartilage in the recent state, and articulates with a
similar shaped surface on the side of the sacrum. The superior portion is con-
cave and rough for the attachment of the posterior sacro-iliac ligaments.
The crest of the ilium is convex in its general outline and sinuously curved,
being bent inwards anteriorly, outwards posteriorly. 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. The surface of the crest is
OS INNOMINATUM.
151
broad, and divided into an external lip, an internal lip, and an intermediate
space.' To the external lip is attached the Tensor vaginae femoris, Obliquus
externus abdominis, and Latissimus dorsi, and by its whole length the fascia
lata ; to the interspace between the lips, the Internal oblique ; to the internal lip,
the Trans versalis, Quadratus lumborum, and Erector spinas.
Fig. 98. — Right Os Innominatum. Internal Surface.
■ MIMUBt'OUIUIA
The anterior border of the ilium is concave. It presents two projections
separated by a notch. Of these, the uppermost, situated at the junction of the
crest and anterior border, is called the anterior superior spinous process of the
ilium, the outer border of which gives attachment to the fascia lata, and the origin
of the Tensor vaginas femoris ; its inner border, to the Iliacus internus ; whilst its
extremity affords attachment to Poupart's ligament, and the origin of the Sartorius.
Beneath this eminence is a notch which gives attachment to the Sartorius muscle,
and across which passes the external cutaneous nerve. Below the notch is the
anterior inferior spinous process, which terminates in the upper lip of the aceta-
bulum ; it gives attachment to the straight tendon of the Kectus femoris muscle.
152 OSTEOLOGY.
On the inner side of the anterior inferior spinous process is a broad shallow groove,
over which passes the Iliacus muscle. The posterior border of the ilium, shorter
than the anterior, also presents two projections separated by a notch, the posterior
superior, and the posterior inferior spinous processes. The former corresponds
with that portion of the posterior surface of the ilium which serves for the
attachment of the sacro-iliac ligaments ; the- latter, to the auricular portion which
articulates with the sacrum. Below the posterior inferior spinous process is a
deep notch, the great sacro-sciatic.
The Ischium forms the lower and back part of the os innominatum. It is divisible
into a thick and solid portion, the body ; and a thin ascending part, the ramus.
The body, somewhat triangular in form, presents three surfaces, external,
internal, and posterior. The external surface corresponds to that portion of the
acetabulum formed by the ischium; it is smooth and concave above, and forms a
little more than two-fifths of that cavity ; its outer margin is bounded by a pro-
minent rim or lip, to which the cotyloid fibro- cartilage 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 outwards to be inserted into
the digital fossa of the femur. The internal surface is smooth, concave, and forms
the lateral boundary of the true pelvic cavity ; it is broad above, and separated
from the venter of the ilium by the linea ilio-pectinea ; narrow below ; its posterior
border is encroached upon a little below its centre, by the spine of the ischium,
above and below which are the greater and lesser sacro-sciatic notches ; in front it
presents a sharp margin, which forms the outer boundary of the obturator foramen.
This surface is perforated by two or three large vascular foramina, and affords
attachment to part of the Obturator internus muscle. The posterior surface is
quadrilateral in form, broad and smooth above, narrow below where it becomes
continuous with the tuberosity ; it is limited, in front, by the margin of the ace-
tabulum ; behind, by the front part of the great sacro-sciatic notch. This surface
supports the Pyriformis, the two Gemelli, and the Obturator internus muscles, in
their passage outwards to the great trochanter. The body of the ischium presents
three borders, posterior, inferior, and internal. The posterior border presents, a
little below the centre, a thin and pointed triangular eminence, the spine of the
ischium, more or less elongated in different subjects. Its external 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, con-
verted into a foramen by the lesser sacro-sciatic ligament ; it transmits the Pyri-
formis muscle, the gluteal vessels and nerve passing out of the pelvis above this
muscle ; the sciatic, and internal pudic vessels and nerve, and a small nerve to the
Obturator internus muscle below it. Below the spine is a smaller notch, the lesser
sacro-sciatic ; it is smooth, coated with cartilage in the recent state, the surface of
which presents numerous markings corresponding to the subdivisions of the tendon
of the Obturator internus which winds over it. It is converted into a foramen by
the sacro-sciatic ligaments, and transmits the tendon of the Obturator internus,
the nerve which supplies this muscle, and the pudic vessels and nerve. The
inferior border is thick and broad ; at its point of junction with the posterior, is a
large rough eminence upon which the body rests in sitting ; it is called the tube-
rosity of the ischium. The internal border is thin, and forms the outer circum-
ference of the obturator foramen.
The tuberosity, situated at the junction of the posterior and inferior borders,
presents for examination an external lip, an internal lip, and an intermediate space.
The external lip gives attachment to the Quadratus femoris, and part of the Ad-
ductor magnus muscles. The inner lip is bounded by a sharp ridge for the attach-
ment of a falciform prolongation of the great sacro-sciatic ligament ; presents a
groove on the inner side of this for the lodgment of the internal pudic vessels
and nerve ; and, more anteriorly, has attached the Transversus perinei, Erector
penis, and Compressor urethra muscles. The intermediate surface presents four
OS INNOMINATUM. 153
distinct impressions. Two of these, seen at the front part of the tuberosity, are
rough, elongated, and separated from each other by a prominent ridge ; the outer
one gives attachment to the Adductor magnus, the inner one to the great sacro-
sciatic ligament. Two, situated at the back part, are smooth, larger in size, and
separated by an oblique ridge; from the upper and outer arises the Semi-mem-
branosus ; from the lower and inner, the Biceps and Semi-tendinosus. The upper-
most part of the tuberosity gives attachment to the Gemellus inferior.
The ramus is the thin flattened part of the ischium, which ascends from the
tuberosity upwards and inwards, and joins the ramus of the pubes, their point of
junction being indicated in the adult by a rough eminence. Its outer surface is
rough for the attachment of the Obturator externus muscle. Its inner surface
forms part of the anterior wall of the pelvis. Its inner border is thick, rough,
slightly everted, forms part of the outlet of the pelvis, and serves for the attach-
ment of the crus penis. Its outer border is thin and sharp, and forms part of the
inner margin of the obturator foramen.
The Pubes forms the anterior part of the os innominatum ; it is divisible into a
horizontal ramus or body, and a perpendicular ramus.
The body or horizontal ramus presents for examination two extremities, an outer
and an inner, and four surfaces. The outer extremity, the thickest part of the bone,
forms one-fifth of the cavity of the acetabulum ; it presents, above, a rough emi-
nence, the ilio-pectineal, which serves to indicate the point of junction of the
ilium and pubes. The inner extremity is the symphysis ; 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 the interarticular
fibro-cartilage, placed between it and the opposite bone. The upper surface,
triangular in form, wider externally than internally, is bounded behind by a sharp
ridge, the pectineal line, or linea ilio-pectinea, which, running outwards, marks the
brim of the true pelvis. The surface of bone in front of the pubic portion of the
linea iliq-pectinea serves for the attachment of the Pectineus muscle. This ridge
terminates internally at a tubercle, which projects forwards, and is called the spine
of the pubes. The portion of bone included between the spine and inner extre-
mity of the pubes is called the crest ; it serves for the attachment of the Rectus,
Pyramidalis, and conjoined tendon of the Internal oblique and Transversalis.
The point of junction of the crest with the symphysis is called the angle of the p>ubes.
The inferior surface presents, externally, a broad and deep oblique groove, for
the passage of the obturator vessels and nerve ; and, internally, a sharp margin,
which forms part of the circumference of the obturator foramen. Its external
surface, flat and compressed, serves for the attachment of muscles. Its internal
surface, convex from above downwards, concave from side to side, is smooth and
forms part of the anterior wall of the pelvis.
The descending ramus of the pubes passes outwards and downwards, becoming
thinner and narrower as it descends, and joins with the ramus of the ischium. Its
external surface is rough, for the attachment of muscles. Its inner surface is
smooth. Its inner border is thick, rough, and everted, especially in females. In
the male, it serves for the attachment of the crus penis. Its outer border forms
part of the circumference of the obturator foramen.
The cotyloid cavity, or acetabulum, is a deep, cup-shaped, hemispherical depres-
sion, formed, internally, by the pubes; 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 pubes. It is
bounded by a prominent uneven rim, which is thick and strong above, and serves
for the attachment of a fibro-cartilaginous structure, which contracts its orifice,
and deepens the surface for articulation. It presents on its inner side a deep
notch, the cotyloid notch, which transmits the nutrient vessels into the interior of
the joint, and is continuous with a circular depression at the bottom of the cavity;
this depression is perforated by numerous apertures, lodges a mass of fat, and its
margins serve for the attachment of the ligamentum teres. The notch is con-
154
OSTEOLOGY.
verted, in the natural state, into a foramen by a dense ligamentous band which
passes across it. Through this foramen, the nutrient vessels and nerves enter the
joint.
The obturator or thyroid foramen is a large aperture, situated between the
ischium and pubes. In the male it is large, of an oval form, its longest diameter
being obliquely from above downwards ; in the female, smaller, and more trian-
gular. It is bounded by a thin uneven margin, to which a strong membrane is
attached; and presents, at its upper and outer part, a deep groove, which runs
from the pelvis obliquely forwards, inwards, and downwards. This groove is
converted into a foramen by the obturator membrane, and transmits the obturator
vessels and nerve.
Structure. This bone consists of much cancellous tissue, especially where it is
thick, inclosed between two layers of dense compact tissue. In the thinner parts
of the bone, as at the bottom of the acetabulum, and centre of the iliac fossa, it
is usually semi-transparent, and composed entirely of compact tissue.
Development (fig. 99). By eight centres ; three primary — one for the ilium, ote
Fig. 99. — Plan of the Development of the Os Innominatum.
•n * ft . I & -Primary (/IvuaniJJic/tiun^tc Pu/hcs j
i 5.Stconda,TTt
The 3 l*rimevry centre* finite fArouyA ~YShetfi€<l Jileee jtilotit JwZerfy
T.pijiJiyses ativear about puberty, $c unite about 26!? year
for the ischium, and one for the pubes ; and five secondary — one for the crest of the
ilium its whole length, 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,
one for the symphysis pubis (more frequent in the female than the male), and one
for the Y-shaped piece at the bottom of the acetabulum. These various centres
appear in the following order : First, in the ilium, at the lower part of the bone,
immediately above the sciatic notch, at about the same period that the develop-
ment of the vertebra? commences. Secondly, in the body of the ischium, at about
the third month of foetal life. Thirdly, in the body of the pubes, between the fourth
and fifth months. At birth, the three primary centres are quite separate ; the crest,
the bottom of the acetabulum, and the rami of the ischium and pubes, being still
PELVIS. 155
cartilaginous. At about the sixth year, the rami of the pubes and ischium are
almost° completely ossified. About the thirteenth or fourteenth year, the three
divisions of the bone have extended their growth into the bottom of the acetabu-
lum, being separated from each other by a Y-shaped portion of cartilage, which
now presents traces of ossification. The ilium and ischium then become joined,
and lastly the pubes, through the intervention of the portion above-mentioned.
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 about the twenty-fifth
year.
Articulations. With its fellow of the opposite side, the sacrum and femur.
Attachment of Muscles. Ilium. To the outer lip of the crest, the Tensor
vaginae femoris, Obliquus externus abdominis, and Latissimus dorsi; to the internal
lip, the Transversalis, Quadratus lumborum, and Erector spinse ; to the interspace
between the lips, the Obliquus internus. To the outer surface of the ilium, the
Gluteus maximus, Gluteus medius, Gluteus minimus, reflected tendon of Rectus,
portion of Pyriformis ; to the internal surface, the Iliacus ; to the anterior border,
the Sartorius and straight tendon of the Eectus. Ischium. To its outer surface,
the Obturator externus; internal surface, Obturator internus and Levator ani.
To the spine, the Gemellus superior, Levator ani, and Coccygeus. To the
tuberosity, the Biceps, Semi-tendinosus, Semi-membranosus, Quadratus femoris,
Adductor magnus, Gemellus inferior, Transversus perinsei, Erector penis. Pubes,
the Obliquus externus, Obliquus internus, Transversalis, Rectus, Pyramidalis,
Psoas parvus, Pectineus, Adductor longus, Adductor brevis, Gracilis, Obtu-
rator externus and internus, Levator ani, Compressor urethral, and occasionally a
few fibres of the Accelerator urinse.
The Pelvis (figs. 100 and 101).
The pelvis, so called from its resemblance to a basin {ni-Kv^), is stronger and
more massively constructed than either of the other osseous cavities already con-
sidered ; it is a bony ring, interposed between the lower end of the spine, which
it supports, and the lower extremities, upon which it rests. It is composed of
four bones — the two ossa innotninata, which bound it on either side and in front ;
and the sacrum and coccyx, which complete it behind.
The pelvis is divided by a prominent line, the linea ilio-pectinea, into a false
and true pelvis.
The false pelvis is all that expanded portion of the pelvic cavity which is
situated above the linea ilio-pectinea. 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, 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 admirably adapted to support the intestines, and to transmit part of their weight
to the anterior wall of the abdomen.
The true pelvis is all that part of the pelvic cavity which is situated beneath
the linea ilio-pectinea. It is smaller than the false pelvis, but its walls are more
perfect. For convenience of description, it may be divided into a superior cir-
cumference or inlet, an inferior circumference or outlet, and a cavity.
The superior circumference forms the margin or brim of the pelvis, the included
space being called the inlet. It is formed by the linea ilio-pectinea, completed
in front by the spine and crest of the pubes, and behind by the anterior margin of
the base of the sacrum and sacro- vertebral angle.
The inlet of the pelvis is somewhat heart-shaped, obtusely pointed in front,
diverging on either side, and encroached upon behind by the projection forwards
of the promontory of the sacrum. It has three principal diameters: antero-
posterior or sacro-pubic, transverse, and oblique. The antero-posterior extends
from the sacro- vertebral angle to the symphysis pubis ; its average measurement
is four inches. The transverse extends across the greatest width of the inlet,
15G
OSTEOLOGY.
from the middle of the brim on one side, to the same point on the opposite- its
average measurement is five inches. The oblique extends from the margin of the
pelvis corresponding to the ilio-pectineal eminence on one side, to the sacro-iliac
symphysis on the opposite side ; its average measurement is also five inches.
Fig. 100.— Male Pelvis (Adult).
Fig. 101.— Female Pelvis (Adult).
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 forwards
above and below, contracts the inlet and outlet of the canal ; and laterally it is
bounded by a broad, smooth, quadrangular plate of bone, corresponding to the
inner surface of the body of the ischium. The cavity is shallow in front, meas-
uring at the symphysis an inch and a half in depth, three inches and a half in
PELVIS. 157
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, and broader in the middle than
at either extremity, from the projection forwards of the sacro-coccygeal column
above and below. This cavity contains, in the recent subject, the rectum, bladder,
and part of the organs of generation. The rectum is placed at the back 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 parts.
The lower circumference 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 eminences are separated by three notches ; one in front, the pubic arch,
formed by the convergence of the rami of the ischia and pubes 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.
The diameters of the outlet of the pelvis are two, antero-posterior and trans-
verse. The antero-posterior extends from the tip of the coccyx to the lower part
of the symphysis pubis ; and the transverse from the posterior part of one ischiatic
tuberosity, to the same point on the opposite side : the average measurement of
both is four inches. The antero-posterior diameter varies with the length of the
coccyx, and is capable of increase or diminution, on account of the mobility of
this bone.
Position of the Pelvis. In the erect posture, the pelvis is placed obliquely with
regard to the trunk of the body ; the pelvic surface of the symphysis pubis looking
upwards and backwards, the concavity of the sacrum and coccyx looking down-
wards and forwards; 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.
This obliquity is much greater in the foetus, and at an early period of life than
in the adult.
Axes of the Pelvis (fig. 102). 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 of
the symphysis pubis. A line carried
at right angles with this, at its middle, Fig. 102.— Vertical Section of the Pelvis, with lines
would correspond at one extremity indicating the Axes of the Pelvis,
with the umbilicus, and at the other
with the middle of the coccyx ; the
axis of the inlet is therefore directed
downwards and backwards. The axis
of the outlet, produced upwards, would
touch the base of the sacrum ; and is
therefore directed downwards and
forwards. The axis of the cavity is
curved like the cavity itself; this
curve corresponds to the concavity
of the sacrum and coccyx, the ex-
tremities 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 its passage through the
pelvis during parturition. It is also
important to the surgeon as indicating fUne
the direction of the force required in
158 OSTEOLOGY.
the removal of calculi from the bladder, and as determining the direction in
which instruments should be used in operations upon the pelvic viscera.
Differences between the Male and Female Pelvis. In the male, the bones are
thicker and stronger, and the muscular eminences and impressions on their sur-
faces more strongly marked. The male pelvis is altogether more massive; its
cavity is deeper and narrower, and the obturator foramina of larger size. In the
female, the bones are lighter and more expanded, the muscular impressions on
their surfaces are only slightly marked, and the pelvis generally is less massive in
structure. The iliac fossae are broad, and the spines of the ilia widely separated ;
hence the great prominence of the hips. The inlet and the outlet are larger ; the
cavity is more capacious, and the spines of \h& ischia project less into it. The
promontory is less projecting, the sacrum wider and less curved,1 and the coccyx
more movable. The arch of the pubes is wider, and its edges more everted.
The. tuberosities of the ischia and the acetabula are wider apart.
In the foetus, and for several years after birth, the pelvis is small in proportion
to that of the adult. The cavity is deep, and the projection of the sacro- vertebral
angle less marked. The antero-posterior and transverse diameters are nearly
equal. About puberty, the pelvis in both sexes presents the general characters
of the adult male pelvis, but after puberty it acquires the sexual characters pecu-
liar to it in adult life.
OF THE THIGH.
The thigh is formed of a single bone, the femur.
The Femur.
The Femur is the longest, largest, and strongest bone in the skeleton, and almost
perfectly cylindrical in 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 gradually inclines
downwards and inwards, so as to approach its fellow towards 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 in 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.
The Upper Extremity presents for examination a head, a neck, and the greater
and lesser trochanters.
The head, which is globular, and forms rather more than a hemisphere, is di-
rected upwards, inwards, and a little forwards, the greater part of its convexity
being above and in front. Its surface is smooth, coated with cartilage in the
recent state, and presents, a little behind and below its centre, an ovoid depression,
for the attachment of the ligamentum teres. 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 of life, and under different circumstances. Before
puberty, it is directed obliquely, so as to form a gentle curve from the axis of the
shaft. In the adult male, it forms an obtuse angle with the shaft, being directed
upwards, inwards, and a little forwards. In the female, it approaches more nearly
a right angle. Occasionally, in very old subjects, and more especially in those
greatly debilitated, its direction becomes horizontal, so that the head sinks below
the level of the trochanter, and its length diminishes to such a degree, that the
head becomes almost contiguous with the shaft. The neck is flattened from before
backwards, contracted in the middle, and broader at its outer extremity, where it
1 It is not unusual to find the sacrum in the female presenting a considerable curve extending
throughout its whole length.
FEMUR.
159
is connected with the shaft, than at its
summit, where it is attached to the head.
It is much broader in the vertical than in
the antero-posterior diameter, and much
thicker below than above, on account of
the greater amount of resistance required
in sustaining the weight of the trunk.
Its anterior surface is perforated by nu-
merous vascular foramina. Its posterior
surface is smooth, broader, and more con-
cave than the anterior ; and receives to-
wards its outer side the attachment of
the capsular ligament of the hip. Its
superior border is short and thick, bounded
externally by the great trochanter, and
its surface perforated by large foramina.
Its inferior border, long and narrow,
curves a little backwards, to terminate at
the lesser trochanter.
The Trochanters (rpo^ow, to run or
roll) are prominent processes of bone
which afford greater leverage to the
muscles which rotate the thigh on its
axis. They are two in number, the
greater, and the lesser.
The Great Trochanter is a large
irregular quadrilateral eminence, situated
at the outer side of the neck, at its junc-
tion with the upper part of the shaft.
It is directed a little outwards and back-
wards ; and, in the adult, is about three
quarters of an inch lower than the head.
It presents for examination two surfaces,
and four borders.
Its external surface, quadrilateral in
form, is broad, rough, convex, and marked
by a prominent diagonal line, which ex-
tends from the posterior superior to the
anterior inferior angle ; this line serves
for the attachment of the tendon of the
Gluteus medius. Above the line is a tri-
angular surface, sometimes rough for part
of the tendon of the same muscle, some-
times smooth for the interposition 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 maxim us muscle
plays, a bursa being interposed. The in-
ternal surface is of much less extent
than the external, and presents at its base
a deep depression, the digital or trochan-
teric fossa, for the attachment of the ten-
don of the Obturator externus muscle.
The superior border is free ; it is thick
and irregular, and marked by impressions
for the attachment of the Pyriformis
Fig. 103.— Right Femur. Anterior Surface.
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160 OSTEOLOGY.
behind, the Obturator interim s and Gemelli in front. The inferior border corre-
sponds to the point of junction of the base of the trochanter with the outer surface
of the shaft ; it is rough, prominent, slightly curved, and 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 by 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 is a conical eminence, which varies in size in different
subjects; it projects from the lower and back part of the base of the neck. Its
base is triangular, and connected with the adjacent parts of the bone by three
well-marked borders : of these, the superior is continuous with the lower border
of the neck ; the posterior, with the posterior intertrochanteric line ; and the inferior,
with the middle bifurcation of the linea aspera. Its summit, which is directed
inwards and backwards, is rough, and gives insertion to the tendon of the Psoas
magnus. The Iliacus is inserted into the shaft below the lesser trochanter, between
the Vastus internus in front, and the Pectineus behind. A well-marked promi-
nence, of variable size, which projects from the upper and front part of the neck,
at its junction with the great trochanter, is called the tubercle of the femur ; it is
the point of meeting of three muscles, the Gluteus minimus externally, the Vastus
externus below, and the tendon of the Obturator internus and Gemelli above.
Eunning obliquely downwards and inwards from the turbercle, is the spiral line
of the femur, or anterior intertrochanteric line ; 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 capsular ligament of the hip -joint; its lower half is less prominent, and gives
attachment to the upper part of the Vastus internus. The posterior intertro-
chanteric line is very prominent, and runs from the summit of the great trochanter
downwards and inwards to the upper and back part of the lesser trochanter. Its
upper half forms the posterior border of the great trochanter. A well-marked
eminence commences about the middle of the posterior intertrochanteric line, and
passes vertically downwards 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.
The Shaft, almost perfectly cylindrical in form, is a little broader above than in
the centre, and somewhat flattened from before backwards below. It is slightly
arched, so as to be convex in front ; concave behind, where it is strengthened by
a prominent longitudinal 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 (fig. 104) is a prominent longitudinal ridge or crest, presenting
on the middle third of the bone an external lip, an internal lip, and a rough inter-
mediate space. A little above the centre of the shaft, this crest divides into three
lines : the most external one becomes very rough, and is continued almost vertically
upwards to the base of the great trochanter : the middle one, the least distinct, is
continued to the base of the trochanter minor ; and the internal one is lost above
in the spiral line of the femur. Below, the linea aspera divides into two bifur-
cations, which inclose between them a triangular space, the popliteal space, upon
which rests the popliteal artery. Of these two bifurcations, the outer branch is
the most prominent, and descends to the summit of the outer condyle. The inner
branch is less marked, presents a broad and shallow groove for the passage of the
femoral artery, and terminates at a small tubercle at the summit of the internal
condyle.
To the inner lip of the linea aspera, its whole length, is attached the Vastus
internus ; and to the whole length of the outer lip, the Vastus externus. The
Adductor magnus is also attached to the whole length of the linea aspera, being
connected with the outer lip above, and the inner lip below. Between the Vastus
FEMUR.
161
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 internus, four
muscles are attached: the Iliacus and
Pectineus above, the latter to the middle
division of the upper bifurcation ; below
these, the Adductor brevis and Adductor
longus. The linea aspera is perforated a
little below its centre by the nutritious
canal, which ip directed obliquely from
below upwards.
The two lateral borders of the femur
are only very slightly marked, the outer
one extending from the anterior inferior
angle of the great trochanter to the an-
terior extremity of the external condyle ;
the inner one passes from the spiral line,
at a point opposite the trochanter minor,
to the anterior extremity of the internal
condyle. The internal border marks this
limit of attachment of the Crureus muscle
internally.
The anterior surface includes that por-
tion 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 forwards and a little
outwards, its lower part forwards and a
little inwards. The upper three-fourths
of this surface serve for the attachment of
the Crureus ; the lower fourth is separated
from this muscle by the intervention of
the synovial membrane of the knee-joint,
and affords attachment to the Subcrureus
to a small extent. 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 ex-
ternal condyle : to its upper three-fourths
is attached the outer portion of the Cru-
reus muscle. The internal surf ace includes
the portion of bone between the internal
border and the inner lip of the linea as-
pera; it is continuous, above, with the
lower border of the neck; below, with
the inner side of the internal condyle : it
is covered by the Vastus internus muscle.
The Lower Extremity, larger than the
upper, is of a cuboid form, flattened from
before backwards, and divided by an
interval presenting a smooth depression
in front, and a notch of considerable size
11
Fig. 104. — Right Femur. Posterior Surface.
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162
OSTEOLOGY.
behind, into two large eminences, the condyles (x6vhvxoi} a knuckle). The interval
is called the intercondyloid notch. The external condyle is the most prominent
anteriorly, and is the broadest both in the antero-posterior and transverse diameters.
The internal condyle is the narrowest, longest, and most prominent internally.
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 conse-
quence 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-
zontal. The two condyles are directly continuous in front, and form a smooth
trochlear surface, the external border of which is more prominent, and ascends
higher than the internal one. This surface articulates with the patella. It pre-
sents a median groove, which extends downwards and backwards to the inter-
condyloid notch ; and two lateral convexities, of which the external is the broader,
more prominent, and prolonged farther upwards upon the front of the outer
condyle. The intercondyloid notch lodges the crucial ligaments ; it is bounded
laterally by the opposed surfaces of the two condyles, and in front by the lower
end of the shaft.
Outer Condyle. The outer surface of the external condyle presents, a little behind
its centre, an eminence, the outer tuberosity ; it is less prominent than the inner
tuberosity, and gives attachment to the external lateral ligament of the knee.
Immediately beneath it is a groove which commences at a depression a little behind
the centre of the lower border of this surface : the depression is for the tendon of
origin of the Popliteus muscle ; the groove in which this tendon is contained is
smooth, covered with cartilage in the recent state, and runs upwards and back-
wards 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 the articular surface
is a depression, for the tendon of the outer head of the Gastrocnemius.
Inner Condyle. The inner surface of the inner condyle presents a convex
eminence, the inner tuberosity, rough for the attachment of the internal lateral
ligament. Above this tuberosity, at the termination of the inner bifurcation of the
linea aspera, is a tubercle, for the insertion of the tendon of the Adductor magnus ;
and behind and beneath the tubercle a depression, for the tendon of the inner head
of the Gastrocnemius. 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 articular surface is convex, and
presents a less extensive surface than the external condyle.
Structure. The shaft of the femur is
a cylinder of compact tissue hollowed
by a large medullary canal. The cylin-
der is of great thickness and density in
the middle third of the shaft, wrhere 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 medullary canal, and
finally obliterate it, so 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
Fig. 105. — Diagram showing the Structure of
the Neck of the Femur. (Ward.)
FEMUR.
133
Fig. 106. — Plan of the Development of the Femur.
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upper end (fig. 105), they run in parallel columns a a from the summit of the head
to the thick under wall of the neck, while a series of transverse fibres b b decus-
sates the parallel columns, and connects them to the thin upper wall of the neck.
Another series of plates c c springs from the whole interior of the cylinder above
the lesser trochanter ; passing upwards, they converge to form a series of arches
beneath the upper wall of the neck, near its junction with the great trochanter.
This structure is admirably adapted to sustain, with the greatest mechanical
advantage, concussion or weight transmitted from above, and serves an important
office in strengthening a part especially liable to fracture.
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 decided perpendicular course, above
the condyles.
Articulations. With three bones : the os innominatum, tibia, and patella.
Development (fig. 106). The
femur is developed by jive centres ;
one for the shaft, one for each ex-
tremity, and one for each trochanter.
Of all the long bones, it is the first
to show traces of ossification: this
first commences in the shaft, at
about the fifth week of foetal life,
the centres of ossification in the
epiphyses appearing in the follow-
ing order: First, in the lower end
of the bone, at the ninth month of
foetal life; from this the condyles
and tuberosities are formed ; in the
head, at the end of the first year
after birth ; in the great trochanter,
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 direct reverse
of their appearance ; their junction
does not commence until after
puberty, the lesser trochanter being
first joined, then the greater, then
the head, and, lastly, the inferior
extremity, the first in which ossi-
fication commenced, which is not
united until the twentieth year.
Attachment of Muscles. To the great trochanter: the Gluteus medius, Gluteus
minimus, Pyriformis, Obturator internus, Obturator externus, Gemellus superior,
Gemellus inferior, and Quadratus femoris. To the lesser trochanter : the Psoas
magnus, and the Iliacus below it. To the shaft : its posterior surface ; the Vastus
externus, Gluteus maximus, short head of the Biceps, Vastus internus, Adductor
magnus, Pectineus, Adductor brevis, and Adductor longus ; to its anterior surface;
the Crureus, and Subcrureus. To the condyles: the Gastrocnemius, Plantaris,
and Popliteus. ,
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THE LEG.
The Leg consists of three bones : the Patella, a larg*
front of the knee ; the Tibia, and Fibula.
sesamoid bone, placed in
1G4
OSTEOLOGY.
Fig. 107.— Right Patella.
Anterior Surface.
The Patella. (Figs. 107 and 108.)
The Patella is a small, flat, triangular bone, situated at the anterior part of the
knee-joint. It resembles the sesamoid bones, from being developed in the tendon
of the Quadriceps extensor, and in its structure, being composed throughout of
dense cancellous tissue; but it is generally regarded as analogous to the olecranon
process of the ulna, which occasionally exists as a separate piece, connected to the
shaft of the bone by a continuation of the tendon of the Triceps muscle.1 It
serves to protect the front of the joint, and increases the leverage of the Common
extensor by making it act at a greater angle. It presents an anterior and posterior
surface, three borders, a base, and an apex.
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, separated from the integument
by a bursa, and gives attachment below to the liga-
mentum patellae. The posterior surface presents a
smooth, oval-shaped, articular surface, covered with
cartilage in the recent state, and divided into two facets
by a vertical ridge, which descends from the superior
towards 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 outer condyle, being the broader and deeper, serves
to indicate the leg 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 ligamentum patellar ; the upper half being separated
from the head of the tibia by adipose tissue.
Its superior and lateral borders give attachment to
the tendon of the Quadriceps extensor; the superior
border, to that portion of the tendon which is derived
from the Eectus and Crureus muscles; and the lateral
borders, to the portion derived from the external and
internal Vasti muscles.
The base or superior border is thick, directed upwards, and cut obliquely at
the expense of its outer surface; it receives the attachment, as already mentioned,
of part of the Quadriceps extensor tendon.
The apex is pointed, and gives attachment to the ligamentum patellae.
Structure. It consists of dense cancellous tissue, covered by a thin compact
lamina.
Development. By a single centre, which makes its appearance, according to
Beclard, about the third year. In two instances, I have seen this bone cartilaginous
throughout, at a much later period (six years). More rarely, the bone is developed
by two centres, placed side by side.
Articulations. With the two condyles of the femur.
Attachment of Muscles. The Eectus, Crureus, Vastus internus, and Vastus
externus. These muscles, joined at their insertion, constitute the Quadriceps ex-
tensor cruris.
Fig. 108.— Right Patella.
Posterior Surface.
1 Professor Owen states, that, "in certain bats, there is a development of a sesamoid
bone in the biceps brachii, which is the true homotype of the patella in the leg," regarding the
olecranon to be homologous, not with the patella, but with an extension of the upper end of
the fibula above the knee-joint, which is met with in some animals. ('■ On the Nature of Limbs,"
pp. 19, 24.)
TIBIA.
1C5
The Tibia.
The Tibia (so named from its
resemblance to 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 pris-
moid in form, expanded above,
where it enters into formation
with the knee-joint, more 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 slight
oblique direction downwards and
outwards, to compensate for the
oblique direction of the femur
itiwards. It presents for exami-
nation a shaft and two extremi-
ties.
The Upper Extremity or head
is large and expanded on each
side into two lateral eminences,
the tuberosities. Superiorly,
the tuberosities present two
smooth concave surfaces, which
articulate with the condyles of
the femur; the internal articular
surface is longer than the ex-
ternal, oval from before back-
wards, to articulate with the
internal condyle; the external
one being broader, flatter, and
more circular, to articulate with
the external condyle. Between
the two articular surfaces, and
nearer the posterior than the
anterior aspect of the bone, is an
eminence, the spinous process of
the tibia, surmounted by a pro*
minent tubercle on each side,
which give attachment to the
extremities of the semilunar
fibro-cartilages ; and in front and
behind the spinous process, a
rough depression for the attach-
ment of the anterior and poste-
rior crucial ligaments and the
semilunar cartilages. Anteriorly
the tuberosities are continuous
with one another, presenting a
large and somewhat flattened
triangular surface, broad above,
and perforated by large vascular
foramina; narrow below, where
it terminates in a prominent
Fig. 109. — Bones of the Right Leg. Anterior Surface.
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1G6 OSTEOLOGY.
oblong elevation of large size, the tubercle of the tibia ; the lower half of this
tubercle is rough, for the attachment of the ligamentum patellae ; the upper half
is a smooth facet corresponding, in the recent state, with a bursa which separates
the ligament from the bone. Posteriorly, the tuberosities are separated from
each other by a shallow depression, the popliteal notch, which gives attach-
ment to the posterior crucial ligament. The posterior surface of the inner
tuberosity presents a deep transverse groove, for the insertion of the tendon of
the Semi-membranosus ; and the posterior surface of the outer one, a flat articular
facet, nearly circular in form, directed downwards, backwards, and outwards, for
articulation with the fibula. The lateral surfaces are convex and rough; the
internal one, the most prominent, gives attachment to the internal lateral
ligament.
The Shaft of the tibia is of a triangular prismoid form, broad above, gradually
decreasing in size to the commencement of its lower fourth, its most slender part,
where fracture most frequently occurs, and then enlarging again towards its lower
extremity. It -presents for examination three surfaces and three borders.
The anterior border, the most prominent of the three, is called the crest of the
tibia, 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 curved outwards above, and inwards
below ; it gives attachment to the deep fascia of the leg.
The internal border is smooth and rounded above and below, but more promi-
nent in the centre ; it commences at the back part of the inner tuberosity, and
terminates at the posterior border of the internal malleolus ; its upper third gives
attachment to the internal lateral ligament of the knee, and to some fibres of the
Popliteus muscle ; its middle third, to some fibres of the Soleus and Flexor longus
digitorum muscles.
The external border 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.
The internal surface 'is smooth, convex, and broader above than below; its
upper third, directed forwards and inwards, is covered by the aponeurosis derived
from the tendon of the Sartorius, and by the tendons of the Gracilis and Semi-
tendinosus, all of which are inserted nearly as far forwards as the anterior
border ; in the rest of its extent it is subcutaneous.
The external surface is narrower than the internal; its upper two-thirds present
a shallow groove for the attachment of the Tibialis anticus muscle ; its lower third
is smooth, convex, curves gradually forwards to the anterior part of the bone,
and is covered from within outwards by the tendons of the following muscles :
Tibialis anticus, Extensor proprius pollicis, Extensor longus digitorum, Peroneus
tertius.
The 'posterior surface (fig. 110) presents at its upper part a prominent ridge,
the oblique line of the tibia, which extends from the back part of the articular facet
for the fibula, obliquely downwards, to the internal border, at the junction of its
upper and middle thirds. It marks the 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 triangular
concave surface, above, and to the inner side of, this line, gives attachment 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 commence-
ment at the oblique line, but becomes gradually indistinct below ; the inner and
broadest half gives attachment to the Flexor longus digitorum, the outer and
narrowest, to part of the Tibialis posticus. The remaining part of the bone is
covered by the Tibialis posticus, Flexor longus digitorum and Flexor longus
TIBIA.
167
pollicis muscles. Immediately
below the oblique line is the
medullary foramen, which is di-
rected obliquely downwards.
The Lower Extremity, much
smaller than the upper, is some-
what quadrilateral in form, and
prolonged downwards on its in-
ner side, into a strong process,
the internal malleolus. The
inferior surface of the bone
presents a quadrilateral smooth
surface, for articulation with the
astragalus ; narrow internally,
where it becomes continuous with
the articular surface of the inner
malleolus, broader externally,
and traversed from before back-
wards by a slight elevation, se-
parating two lateral depressions.
The anterior surface is smooth
and rounded above, and covered
by the tendons of the Extensor
muscles of the toes; its lower
margin presents a rough trans-
verse depression, for the attach-
ment of the anterior ligament of
the ankle-joint. The posterior
surface presents a superficial
groove directed obliquely down-
wards and inwards, continuous
with a similar groove on the pos-
terior extremity of the astragalus ;
it serves for the passage of the
tendon of the Flexor longus polli-
cis. The external surface presents
a triangular rough depression,
the lower part of which, in some
bones, is smooth, and covered
with cartilage in the recent state,
and articulates with the fibula;
the remaining part is rough for
the attachment of the inferior
interosseous ligament, which
connects it with the fibula.
This surface is bounded by two
prominent ridges, continuous
above with the interosseous
ridge ; they afford attachment
to the anterior and posterior
tibio-fibular ligaments. The
internal surface is prolonged
downwards to form a strong py-
ramidal-shaped process, flattened
from without inwards, the inner
malleolus; its inner surface is
convex and subcutaneous. Its
Fig. 110. — Bones of the Eight Leg. Posterior Surface.
■tfloidji rticesa
168
OSTEOLOGY.
Fig. 111.— Plau of the Development of the Tibia.
By 3 Centres.
Upper extremity
Apj>»t{ rx <il birth
Tovns Shaft about
2S 0 yr
outer surface, smooth and slightly concave, deepens the articular surface for the
astragalus. Its anterior border is rough, for the attachment of ligamentous fibres.
Its posterior border presents a broad and deep groove, directed obliquely down-
wards and inwards ; it is occasionally double, and transmits the tendons of the
Tibialis posticus and Flexor longus digitorum muscles. Its summit 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.
Development. By three centres (fig. Ill): one for the shaft, and one for each
extremity. Ossification commences in the centre of the shaft about the same time
as in the femur, the fifth week, and
gradually extends towards either ex-
tremity. The centre for the upper
epiphysis appears at birth ; it is flat-
tened 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 twentieth year, and the
upper one about the twenty-fifth
year. Two additional centres occa-
sionally exist, one for the tongue-
shaped process of the upper epiphysis,
the tubercle, and one for the inner
malleolus.
Articulations. With three bones:
the femur, fibula, and astragalus.
Attachment of Muscles. To the
inner tuberosity, the Semi-membra-
nosus. To the outer tuberosity, the
Tibialis anticus and Extensor longus
digitorum. To the shaft ; its internal
surface, the Sartorius, Gracilis, and
Semi-tendinosus : to its external sur-
face, the Tibialis anticus : to its pos-
terior surface, the Popliteus, Soleus,
Flexor longus digitorum, and Tibialis posticus : to the tubercle, the ligamentum
patellae.
The Fibula.
The Fibula 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 nearly parallel with the tibia, its upper extremity is small, placed
below the level of the knee-joint, and excluded from its formation ; but the
lower extremity inclines a little forwards, 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.
The Upper Extremity or Head is of an irregular rounded form, presenting,
above, a flattened articular facet, directed upwards and inwards, for articulation
with a corresponding facet on the external tuberosity of the tibia. On the outer
side is a thick and rough prominence, continued behind into a pointed eminence,
the styloid process, which projects upwards from the posterior part of the head.
The prominence above mentioned gives attachment to the tendon of the Biceps
muscle, and to the long external lateral ligament of the knee, the ligament dividing
this tendon into two parts. The summit of the styloid process gives attachment
to the short external lateral ligament. The remaining part of the circumference
Appears at 2!^«i
h-uwr extrewiuJ
thea*
FIBULA. 160
of the head is rough, for the attachment, in front, of the anterior superior tibio-
fibular ligament, and the upper and anterior part of the Peroneus longus ; and
behind, to the posterior superior tibio-fibular ligament, and the upper fibres of the
outer head of the Soleus muscle.
The Lower Extremity or external malleolus is of a pyramidal form, some-
what flattened from without inwards, and is longer, and descends lower, than
the internal malleolus. Its external surface is convex, subcutaneous, and con-
tinuous with a triangular surface, also subcutaneous, on the outer side of the shaft.
The internal surface presents in front a smooth triangular facet, broader above
than below, convex from above downwards, which articulates with a correspond-
ing 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, for the passage of the tendons of the Peroneus longus and Peroneus
brevis muscles. Its summit is rounded, and gives attachment to the middle fasci-
culus of the external lateral ligament.
The Shaft presents three surfaces, and three borders. The anterior border com-
mences above in front of the head, runs vertically downwards to a little below the
middle of the bone, and then, curving a little outwards, bifurcates below into two
lines, which bound the triangular subcutaneous surface immediately above the
outer side of the external malleolus. It gives attachment to an intermuscular
septum, which separates the muscles on the anterior surface from those on the
external.
The internal border or interosseous ridge is situated close to the inner side of
the preceding ; it 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, and separates the
extensor muscles in front, from the flexor muscles behind. The portion of bone
included between the anterior and interosseous lines forms the anterior surface.
The posterior border is sharp and prominent ; it commences above at the bass
of the styloid process, and terminates below in the posterior border of the outer
malleolus. It is directed outwards above, backwards in the middle of its course,
backwards and a little inwards below, and gives attachment to an aponeurosis
which separates the muscles on the outer from those on the inner surface of the
shaft. The portion of bone included between this line and the interosseous ridge
forms the internal surface. Its upper three-fourths are subdivided into two parts,
an anterior and a posterior, by a very prominent ridge, the oblique line of the fibula,
which commences above at the inner side of the head, and terminates by being
continuous with the interosseous ridge at the lower fourth of the bone. It attaches
an aponeurosis which separates the Tibialis posticus from the Soleus above, and
the Flexor longus pollicis below. This ridge sometimes ceases just before ap-
proaching the interosseous ridge.
The anterior surface is the interval between the anterior and interosseous lines.
It is extremely narrow and fiat 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 longus pollicis.
The external surface, much broader than the preceding, is directed outwards in
the upper two-thirds of its course, backwards in the lower third, where it is con •
tinuous with the posterior border of the external malleolus. This surface is com-
pletely occupied by the Peroneus longus and Peroneus brevis muscles.
The internal surface is the interval between the interosseous ridge and the
posterior border, and occupies nearly two-thirds of the circumference of the bone.
no
OSTEOLOGY.
Fig. 112. — Plan of the Development of
the Fibnla. By 3 Centres.
IXtfr
Vrwtvt aiou t25(tijZ
Its upper three-fourths are divided into an anterior and a posterior portion by a
very prominent ridge already mentioned, the oblique line of the fibula. The
anterior portion is directed inwards, and is grooved for the attachment of the
Tibialis posticus muscle. The posterior portion is continuous below with the
rough triangular surface above the articular facet of the outer malleolus ; it is
directed backwards above, backwards and inwards at its middle, directly inwards
below. Its upper fourth 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 pollicis muscle. At about the middle
of this surface is the nutritious foramen, which is directed downwards.
In order to distinguish the side to which the bone belongs, hold it with the
lower extremity downwards, and the broad
groove for the Peronei tendons backwards, to-
wards 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. 112):
one for the shaft, and one for each extremity.
Ossification commences in the shaft about the
sixth week of foetal life, a little later than in
the tibia, and extends gradually towards 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, con-
trary to the law which appears to prevail with
regard to the junction of the epiphysis with the
shaft ; the upper one is joined about the twenty-
fifth year.
Attachment of Muscles. To the head; the
Biceps, Soleus, and Peroneus longus. To the
shaft, its anterior surface ; the Extensor longus
digitorum, Peroneus tertius, and Extensor lon-
gus pollicis : to the internal surface ; the Soleus,
Tibialis posticus, and Flexor longus pollicis : to
the external surface ; the Peroneus longus and brevis.
Al'fW ixat2™<y^L
-Unit.** alout2C?!y?
exit*
THE FOOT.
The Foot (figs. 113 and 114) is the terminal part of the inferior extremity; it
serves to support the body in the erect posture, and is an important instrument of
locomotion. It consists of three divisions : the Tarsus, Metatarsus, and Phalanges.
The Taksus.
The bones of the Tarsus are seven in number ; viz., the calcaneum or os calcis,
astragalus, cuboid, scaphoid, internal, middle, and external cuneiform bones.
The Calcaneum.
The Calcaneum or Os Calcis is the largest and strongest of the tarsal bones.
It is irregularly cuboidal in form, and situated at the lower and back part of the
TARSUS.
Fig. 313.— Bones of the Right Foot. Dorsal Surface.
171
Groove for PFRONEUS LONCUS
Groove far peroneus ERE vis
PCRONCUS TtFTiu
FERONEUS BRCVIS
Cnxme for ten Jim of
FLEXOR LONCUS POLL, CIS
jTo-TgU*
Metatarsus
TnittVTtiett Utuiifn <if
EXT. BREVIS OICITORUM
Thalanqes
EXT. LONCUS PBLLICIS
172 OSTEOLOGY.
foot, serving to transmit the weight of the body to the ground, and forming a
strong lever for the muscles of the calf. It presents for examination six surfaces ;
superior, inferior, external, internal, anterior, and posterior.
The superior surface is formed behind, of the upper aspect of that part of the
os calcis which projects backwards to form the heel. It varies in length in
different individuals ; is convex from side to side, concave from before backwards,
and corresponds above to a mass of adipose substance placed in front of the tendo
Achillis. In the middle of this surface are two, sometimes three, articular
facets, separated by a broad shallow groove, directed obliquely forwards and
outwards, and rough for the attachment of the interosseous ligament connecting
the astragalus and os calcis. Of these two articular surfaces, the external is the
larger, and situated on the body of the bone; it is of an oblong form, wider
behind than in front, and convex from before backwards. The interval articular
surface is supported on a projecting process of bone, called the lesser process of the
calcaneum (sustentaculum tali); it is of an oblong form, concave longitudinally,
and sometimes subdivided into two, which differ in size and shape. More ante-
riorly is seen the upper surface of the greater process, marked by a rough
depression for the attachment of numerous ligaments, and the Extensor brevis
digitorum muscle.
The inferior surface is narrow, rough, uneven, wider behind than in front, and
convex from side to side ;• it is bounded posteriorly by two tubercles, separated
by a rough depression: the external, small, prominent, and rounded, gives attach-
ment to a part of the Abductor minimi digiti ; the internal, broader and larger,
for the support of the heel, gives attachment, by its prominent inner margin, to
the Abductor pollicis, and in front to the Flexor brevis digitorum muscles; the
depression between the tubercles attaches the Abductor minimi digiti, and plantar
fascia. The rough surface in front of the tubercles gives attachment to the long
plantar ligament ; and to a prominent tubercle nearer the anterior part of the bone,
as well as to a transverse groove in front of it", is attached the short plantar ligament.
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. Behind the tubercle is a broad smooth surface, giving attach-
ment, at its upper and anterior part, to the external astragalo- calcanean ligament ;
and in front of the tubercle a narrow surface marked by two oblique grooves,
separated by an elevated ridge: the superior groove transmits the tendon of the
Peroneus brevis; the inferior, the tendon of the Peroneus longus; the intervening
ridge gives attachment to a prolongation from the external annular ligament.
The internal surface presents a deep concavity, directed obliquely downwards
and forwards, for the transmission of the plantar vessels and nerves and Flexor
tendons into the sole of -the foot; it affords attachment t-> part of the Flexor
accessorius muscle. This surface presents an eminence of 'urne, the lesser process,
which projects horizontally inwards from its upper and 1 re part. This process
is concave above, and supports the anterior articular surface of the astragalus ;
below, it is convex, and grooved for the tendon of the Flexor longus pollicis.
Its free margin is rough, for the attachment of ligaments.
The anterior surface, of a somewhat triangular form, is smooth, concavo-convex,
and articulates with the cuboid. It is surmounted, on its outer side, by a rough
prominence, which forms an important guide to the surgeon in the performance
of Chopart's operation.
The posterior surface is rough, prominent, convex, and wider below than above.
Its lower part is rough, for the attachment of the tendo Achillis ; its upper part
smooth, coated with cartilage, and corresponds to a bursa which separates this
tendon from the bone.
Articulations. With two bones : the astragalus and cuboid.
Attachment of Muscles. Part of the Tibialis posticus, the tendo Achillis, Plan-
taris, Abductor pollicis, Abductor minimi digiti, Flexor brevis digitorum, Flexor
accessorius, and Extensor brevis digitorum.
tarsus. m
The Cuboid.
The Cuboid bone is placed on the outer side of the foot, in front of the os calcis,
and behind the fourth and fifth metatarsal bones. It is of a pyramidal shape, its
base being directed upwards and inwards, its apex downwards and outwards.
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 :
the non-articular surfaces are the superior, inferior, and external.
The superior or dorsal surface, directed upwards and outwards, is rough, for the
attachment of numerous ligaments. The inferior or plantar surface presents in
front a deep groove, wrhich runs obliquely from without, forwards and inwards ;
it lodges the tendon of the Peroneus longus, and is bounded behind by a promi-
nent ridge, terminating externally in an eminence, the tuberosity of the cuboid,
the surface of which presents a convex facet, for articulation with the sesamoid
bone of the tendon contained in the groove. The ridge and surface of bone
behind it are rough, for the attachment of the long and short plantar ligaments.
The external surface, the smallest and narrowest of the three, presents a deep
notch, formed by the commencement of the peroneal groove.
The articular surfaces are the posterior, anterior, and internal. The posterior
surface is smooth, triangular, concavo-convex, for articulation with the anterior
surface of the os calcis. The anterior, of smaller size, but also irregularly trian-
gular, is divided by a vertical ridge into two facets ; the inner facet, 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 quadrilateral, presenting at its middle and upper part a
small oval facet, for articulation with the external cuneiform bone ; and behind
tliis. occasionally, a smaller facet, for articulation with the scaphoid ; it is rough
in the rest of its extent, for the attachment of strong interosseous ligaments.
To ascertain to which foot it belongs, hold the bone so that its under surface,
marked by the peroneal groove, looks downwards, and the large concavo-convex
articular surface backwards, towards the holder ; the narrow non-articular surface,
marked by the commencement of the peroneal groove, will point to the side to
wiiich 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 pollicis.
The Asteagalus.
The Astragalus (fig. 113), next to the os calcis, is the largest of the tarsal bones.
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, 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
presents six surfaces for examination.
The superior surface presents, behind, a broad smooth trochlear surface, for
articulation with the tibia ; it is broader in front than behind, convex from before
backwards, slightly concave from side to side. In front of the trochlea is the
upper surface of the neck of the astragalus, rough for the attachment of liga-
ments. The inferior surface presents two articular facets separated by a deep
groove. The groove runs obliquely forwards and outwards, becoming gradually
broader and deeper in front : it corresponds with a similar groove upon the upper
surface of the os calcis, and forms, when articulated with that bone, a canal, filled
up in the recent state by the calcaneo-astragaloid interosseous ligament. Of the
two articular facets, the posterior is the larger, of an oblong form, and deeply
concave from side to side : the anterior, although nearly of equal length,, is. nar-
OSTEOLOGY.
Fig. 114.— Bones of the Right Foot. Plantar Surface.
LEXOR BREVI* POUICIC
Taltrcle of
ScajJuid
TIBIALIS AMICUS
FLEXOR L0NCU8
DIClTORUM
TARSUS. 175
rower, of an elongated oval form, convex longitudinally, and often subdivided
into two by an elevated ridge : of these the posterior one articulates with the lesser
process of the os calcis ; the anterior one, with the upper surface of the calcaneo-
scaphoid ligament. The internal surface presents at its upper part a pear-shaped
articular facet 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. The external surface presents a large
triangular facet, concave from above downwards, for articulation with the external
malleolus ; it 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. The anterior surface, convex and rounded, forms the head of the
astragalus ; it is smooth, of an oval form, and directed obliquely- inwards and
downwards ; it is continuous below with that part of the anterior facet on the
under surface which rests upon the calcaneo-scaphoid ligament. The head is sur-
rounded by a constricted portion, the neck of the, astragalus. The posterior sur-
face is narrow, and traversed by a groove, which runs obliquely downwards and
inwards, and transmits the tendon of the Flexor longus pollicis.
To ascertain to which foot it belongs, hold the bone with the broad articular
surface upwards, and the rounded head forwards ; the lateral triangular articular
surface for the external malleolus will then point to the side to which the bone
belongs.
Articulations. With four bones : tibia, fibula, os calcis, and scaphoid.
The Scaphoid.
The Scaphoid or Navicular bone, so called from its fancied resemblance to a
boat, is situated at the inner side of the tarsus, between the astragalus behind and
the three cuneiform bones in front. This bone may be distinguished by its boat-
like form, being concave behind, convex and subdivided into three facets in front.
The anterior surface, of an oblong form, is convex from side to side, and sub-
divided 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, somewhat concave, irregular, and also rough for the attachment of
ligaments. The internal surface presents a rounded tubercular eminence, the
tuberosity of the scaphoid, which gives attachment to part of the tendon of the
Tibialis posticus. The external surface is broad, 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 it belongs, hold the bone with the concave articular
surface backwards, and the broad dorsal surface upwards ; the broad external
surface 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.
The Cuneiform Bones.
The Cuneiform Bones have received their name from their wedge-like shape.
They form with the cuboid the most anterior row of. the tarsus, being placed
between the scaphoid behind, the three innermost metatarsal bones in front, and
the cuboid 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, middle,
and external.
The Internal Cuneiform.
The Internal Cuneiform is the largest of the three. It is situated at the inner
side of the foot, between the scaphoid behind and the base of the first metatarsal
176 OSTEOLOGY.
in front. It may be distinguished by its large size, as compared with the other
two, and from its more irregular wedge-like form. It presents for examination
six 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, over which the tendon of the Tibialis anticus muscle glides ; rough in
the rest of its extent, for the attachment of ligaments. The external surface is
concave, presenting, along its superior and posterior borders, a narrow 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
prominent below, where it forms part of the tuberosity. The anterior surface,
reniform in shape, 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 upwards and
outwards ; it is rough for the attachment of ligaments.
To ascertain to which side it belongs, hold the bone so that its superior narrow
edge looks upwards, and the long articular surface forwards ; 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, and first and
second metatarsal bones.
Attachment of Muscles. The Tibialis anticus and Tibialis posticus.
The Middle Cuneifokm.
The Middle Cuneiform, the smallest of the three, is of very regular wedge-
like form ; the broad extremity being placed upwards, the narrow end downwards.
It is situated between the other two bones of the same name, and corresponds to
the scaphoid behind, and the second metatarsal in front.
The anterior surface, triangular in form, and narrower than the posterior, arti-
culates with the base of the second metatarsal bone. The posterior surface, also
triangular, articulates with the scaphoid. The internal surface presents an articular
facet, running along the superior and posterior borders, for articulation with the
internal cuneiform, and is rough below 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 surface, pointed and tubercular, is also rough for liga-
mentous attachment.
To ascertain to which foot the bone belongs, hold its superior or dorsal surface
upwards, the broadest edge being towards the holder, and the smooth facet, limited
to the posterior border, will point to the side to which it belongs.
Articulations. With four bones : scaphoid, internal and external cuneiform, and
second metatarsal bone.
The External Cuneiform.
The External Cuneiform, intermediate in size between the two preceding, is of
a very regular wedge-like form, the broad extremity being placed upwards, the
narrow end downwards. 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 has six surfaces for examination.
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
METATARSAL BONES. ITT
presents two articular facets separated by a rough depression ; the anterior one,
situated at the superior angle of the bone, 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 the cuboid is usually separate. The
superior or dorsal surface, of an oblong form, is rough for the attachment of liga-
ments. 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 pollicis, and ligaments.
To ascertain to which side it belongs, hold the bone with the broad dorsal
surface upwards, the prolonged edge backwards ; 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. Part of Tibialis posticus, and Flexor brevis pollicis.
The Metatarsal Bones.
The Metatarsal bones are five in number ; they are long bones, and subdivided
into a shaft, and two extremities.
The Shaft 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.
The Posterior Extremity or Base is wedge-shaped, articulating by its terminal
surface with the tarsal bones, and by its lateral surfaces with the contiguous bones ;
its dorsal and plantar surfaces being rough, for the attachment of ligaments.
The Anterior Extremity or Head presents a terminal rounded articular surface,
oblong from above downwards, and extending further backwards 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 Metatarsal Bones.
The First is remarkable for its great size, but is the shortest of all the meta-
tarsal bones. The shaft is strong, and of well-marked prismoid form. The
posterior extremity presents no lateral articular facets ; its terminal articular surface
is of large size, of semilunar form, and its circumference grooved for the tarso-
metatarsal ligaments ; its inferior angle presents a rough oval prominence, 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 sesamoid bones, the
facets being separated by a smooth elevated ridge.
The Second is the longest and largest of the remaining metatarsal bones ; being
prolonged backwards, into the recess formed between the three cuneiform bones.
Its tarsal extremity is broad above, narrow and rough below. It presents four
articular surfaces: one behind, of a triangular form, for articulation with the
middle cuneiform ; one at the upper part of its internal lateral surface, for articu-
lation with the internal cuneiform; and two on its external lateral surface, a
superior and an inferior, separated by a rough depression. Each of the latter
articular surfaces is divided by a vertical ridge into two parts ; the anterior seg-
12
178 OSTEOLOGY.
merit of each facet articulates with the third metatarsal; the two posterior
sometimes continuous with the external cuneiform.
The Third articulates behind, by means of a triangular smooth surface, with the
external cuneiform ; 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 Fourth is smaller in size than the preceding ; its tarsal extremity presents
a. terminal quadrilateral 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 cunei-
form ; on the outer side a single facet, for articulation with the fifth metatarsal.
The Fifth is recognized by the tubercular eminence on the outer side of its
base ; it articulates behind, by a triangular surface cut obliquely from without
inwards, with the cuboid ; and internally, with the fourth metatarsal.
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.
Attachment of Muscles. To the first metatarsal bone, three : part of the Tibialis
anticus, Peroneus longus, and First dorsal interosseous. To the second, three : the
Adductor pollicis, and First and Second dorsal interosseous. To the third, four :
the Adductor pollicis, Second and Third dorsal interosseous, and First plantar.
To the fourth, four : the Adductor pollicis, Third and Fourth dorsal, and Second
plantar interosseous. To the fifth, five : the Peroneus brevis, Peroneus tertius,
Flexor brevis minimi digiti, Fourth dorsal, interosseous and Third plantar inter-
osseous.
Phalanges.
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 phalanges of the first row resemble closely those of the hand. The shaft 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 phalanges.
The phalanges of the second row are remarkably small and short, but rather
broader than those of the first row.
The ungual phalanges, in form, resemble those of the fingers ; but they are
smaller, flattened from above downwards, presenting a broad base for articulation
with the second row, and an expanded extremity for the support of the nail and
end of the toe.
Articulations. The first row, with the metatarsal bones, and second phalanges ;
the second of the great toe, with the first phalanx, and of the other toes, with the
first and third phalanges ; the third, with the second row.
Attachment of Muscles. To the first phalanges : Great toe ; innermost tendon of
" Extensor brevis digitorum, Abductor pollicis, Adductor pollicis, Flexor brevis
pollicis, Transversus pedis. Second toe ; First and Second dorsal interosseous.
Third toe; Third dorsal and First plantar interosseous. Fourth toe; Fourth
dorsal and Second plantar interosseous. Fifth toe ; Flexor brevis minimi digiti,
Adductor minimi digiti, and Third plantar interosseous. — Second phalanges:
Great toe ; Extensor longus pollicis, Flexor longus pollicis. Other toes ; Flexor
brevis digitorum, one slip from the Extensor brevis digitorum, and Extensor
longus digitorum. — 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. 115.)
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
SESAMOID BONES.
H9
appearance in the following order : in the os calcis, at the sixth month of fcetal life ;
in the astragalus, about the seventh month ; in the cuboid, at the ninth month ,
external cuneiform, during the first year ; internal cuneiform, in the third year ;
middle cuneiform, 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.
Fig. 115. — Plan of the Development of the Foot.
' s is
Ml
■Jpp.f /O* ■•/.?
unites after p-ulerty
Tarsus
f Centre for e&eJi ione
tacept Os Calcts
Metatarsus
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1 for Shaft
1 for Digital Extremity
except 1.&
cent
Jippcars 6t? yf
\ UiiiU/8-Z0# y.:
- App. 7&mi
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iCentresfor each bo7i0
tforSliaft
f fin Metatarsal Ext J
TfniU 18-20 jf.rf
App'3?dy.
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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. Ossification commences
in the centre of the shaft about the seventh week, and extends towards either
extremity, and in the digital epiphyses about the third year ; 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.
Sesamoid Bones.
These are small rounded masses, cartilaginous in early life, osseous in the adult,
which are developed in those tendons which exert a certain 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
180 OSTEOLOGY.
than in those that 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 joints, and those which play over the
cartilaginous facets found on the surfaces of certain bones.
The sesamoid bones of the joints are, in the lower extremity, the patella, which
is developed in the tendon of the Quadriceps extensor ; two small sesamoid bones,
found opposite the metatarso-phalangeal joint of the great toe in each foot, in the
tendons of the Flexor brevis pollicis, and occasionally one in the metatarso-
phalangeal joint of the second toe, the little toe, and, still more rarely, in the
third and fourth toes.
In the upper extremity, there are two on the palmar surface of the metacarpo-
phalangeal joint in the thumb, developed in the tendons of the Flexor brevis
pollicis. 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.
Those found in tendons which glide over certain bones occupy the following
situations. 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 on the internal cuneiform bone. One in the
tendon of the Tibialis posticus, opposite the inner side of the astragalus. One in
the outer head of the Gastrocnemius, behind the outer condyle of the femur; and
one in the Psoas and Iliacus, where they glide over the body of the pubes.
Occasionally in the tendon of the Biceps, opposite the tuberosity of the radius ;
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 author has to acknowledge valuable aid derived from the perusal of the works of Cloquet,
Cruveilhier, Bourgery, and Boyer, especially of the latter. Reference has also been made to
the following: "Outlines of Human Osteology," by F. O. Ward. "A Treatise on the Human
Skeleton, and Observations on the Limbs of Vertebrate Animals," by G. M. Humphry. Holden's
"Human Osteology." Henle's "Handbuch der Systematischen Anatomie des Menschen. Erster
Band. Erste Abtheilung. Knochenlehre." " Osteological Memoirs (The Clavicle)," by Stru-
thers. "On the Archetype and Homologies of the Vertebrate Skeleton," and "On the Nature
of Limbs," by Owen. — Todd and Bowman's "Physiological Anatomy," and Kolliker's "Manual
of Human Microscopic Anatomy," contain the most complete account of the structure and
development of bone. — The development of the bones is minutely described in "Quain's Ana-
tomy," edited by Sharpey and Ellis. On the chemical analysis of bone, refer to "Lehmann's
Physiological Chemistry," translated by Day, vol. iii. p. 12. "Simon's Chemistry," translated
by Day, vol. ii. p. 396. A paper by Dr. Stark, "On the Chemical Constitution of the Bones of
the Yerteb rated Animals" (Edinburgh Medical and Surgical Journal, vol. liii. p. 308) ; and Dr.
Owen Rees's paper in the 21st vol. of the Medico-chirurgical Transactions.
The Articulations.
The various bones of which the Skeleton consists are connected together at
different parts of their surfaces, and such connection is designated by the name
of Joint or Articulation. If the joint is immovable, as between the cranial and
most of the facial bones, the adjacent margins are applied in almost close
contact, a thin layer of fibrous membrane, the sutural ligament, and, at the base
of the skull, in certain situations, 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 of the
spine, the sacro-iliac, and interpubic articulations; but in the movable joints, the
bones forming the articulation are generally expanded for greater convenience of
mutual connection, covered by an elastic structure, called cartilage, held together
by strong bands or capsules, of fibrous tissue, called ligament, and lined by a
membrane, the synovial membrane, which secretes a fluid that lubricates 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 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, consisting of spongy cancellous tissue, with a thin coating of
compact substance. In the flat bones, the articulations usually take place at the
edges ; and, in the short bones, by various parts of their surface. 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 lacunas 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, andkdo not perforate
it; this la}''er is consequently more dense, and firmer than ordinary bone, and
is evidently designed to form a steady and unyielding support for the articular
cartilage.
Cartilage is firm, opaque, of a pearly-white or bluish-white color, in some
varieties yellow, highly elastic, readily yielding to pressure, and recovering its
shape when the force is removed, flexible, and possessed of considerable cohesive
power. In man, that form of cartilage which constitutes the original framework
of the body, and which in time becomes ossified throughout the greater part of its
extent, is called temporary cartilage. But there is another form of cartilage em-
ployed in the construction of the body that is not prone to ossify, viz., permanent
cartilage. This is found — 1. In the joints, covering the ends of the bones
(articular cartilage) : 2. Forming a considerable part of the solid framework of
the chest (costal cartilages) : 3. Arranged in the form of plates or lamellas, of
greater or less thickness, which enter into the formation of the external ear, the
nose, the eyelids, the Eustachian tube, the larynx, and the windpipe (reticular
cartilage). They serve to maintain the shape of canals or passages, or to form
tubes that require to be kept permanently open without the expenditure of vital
force.
Structure. Cartilage consists either of a parenchyma of nucleated cells, or the cells are
imbedded in an intercellular substance or matrix. The cells or cartilage corpuscles are contained
in hollow cavities or lacunae in thp intercellular substance, which appear to be lined by a firm,
clear, or yellowish layer, the cartilage capsule. Under the influence of certain rea»erns, the
181
182 ARTICULATIONS.
cartilage cell shrinks up, and is separated from its capsule by a well-marked interval. The car-
tilage cells are usually round or oblong, sometimes flattened or fusiform. Each contains a nucleus,
furnished occasionally with one or two nucleoli. The nuclei vary from 25,(5n to ^'j,, of an inch;
they sometimes contain fat globules, or appear converted into fat. The intercellular substance
is either homogeneous, or finely granular, or fibrous.
In temporary cartilage, the intercellular substance is not abundant ; but the cartilage cells
are numerous, and situated at nearly equal distances apart. The cells vary in shape and size,
the majority being round or oval, and their nuclei are minutely granular. When ossification
commences in it, the cells become arranged in clusters or rows, the ends of which are directed
towards the ossifying part.
In articular cartilage, the intercellular substance is more abundant than in the former variety;
it appears dim, like ground glass, and has a finely granular or homogeneous aspect. The cells
are oval or roundish, from j^ViT to 9Hjy of an inch, the nuclei small and commonly vesicular, and
parent cells are frequently seen inclosing two or more younger cells. On the surface of the
cartilage the cells are numerous, and disposed in isolated groups of two, three, or four, the groups
being flattened, and lie with their planes parallel to the surface. In the interior, and nearer the
bone, they are less numerous, and assume more or less of a linear direction, pointing towards the
surface. This arrangement appears to be connected with a corresponding peculiarity of structure
in the matrix, and serves to explain the disposition which this form of cartilage has to break in a
direction perpendicular to the surface, the broken surface being to the eye striated in the same
direction.
In the costal cartilages, the intercellular substance is very abundant, finely mottled, and, in
certain situations, presents a distinctly fibrous structure, the fibres being fine and parallel.
This is most evident in advanced age. The cells, which are collected into groups, are larger
than in any other cartilages of the body, being from ^ to T£5 of an inch in diameter. Many
contain two or more clear transparent nuclei, and some contain oil globules. Near the exterior
of the cartilage the cells are flattened, and lie parallel with the surface ; in the interior, the cells
have a linear arrangement, the separate rows being turned in all directions.
The ensiform cartilage of the sternum, the cartilages of the nose, and the cartilages of the
larynx and windpipe (excepting the epiglottis and cornicula laryngis) resemble the costal carti-
lages in their microscopic characters.
Reticular cartilage. The epiglottis, the cornicula laryngis, the cuneiform cartilages, the carti-
lage of the ear, of the eyelid, and of the Eustachian tube, are included in a separate class under
the name of " reticular," " yellow," or " spongy" cartilages. They are yellow, of a spongy texture
throughout, more flexible than ordinary cartilage, and not prone to ossify. This variety of
cartilage consists of an intercellular substance, composed of minute opaque fibres, which inter-
sect each other in all directions, and are so arranged as to inclose numerous small oval spaces,
in which the cartilage corpuscles are deposited.
Articular cartilage forms a thin incrustation upon the articular surfaces of
bones, and is admirably adapted, by its elastic property, to break the force of con-
cussions, and, by^ts smoothness, to afford perfect ease and freedom of movement
between the bones. Where it covers the rounded ends of bones, upon which the
greatest pressure is received, it is thick at the centre, and becomes gradually
thinner towards the circumference : an opposite arrangement exists where it lines
the corresponding cavities. On the articular surfaces of the short bones, as the
carpus and tarsus, the cartilage is disposed in a layer of uniform thickness through-
out. The attached surface of articular cartilage is closely adapted, by a rough,
uneven surface, to the articular lamella ; the free surface is smooth, polished, and
partially covered by a perichondrium, prolonged from the periosteum, a short dis-
tance over the cartilage ; in the foetus, an extremely thin prolongation of synovial
membrane may be traced over the surface of the cartilage, according to Mr. Toynbee,
but, at a later period of life, this cannot be demonstrated. Articular cartilage in
the adult does not contain bloodvessels; its nutrition being derived from the
vessels of the synovial membrane which skirt the circumference of the cartilage,
and from those -of the adjacent bone, which are, however, separated from direct
contact with the cartilage by means of the articular lamella. Mr. Toynbee has
shown, that the minute vessels of the cancellous tissue, as they approach the
articular lamella, dilate, and, forming arches, return into the substance of the bone.
The vessels of the synovial membrane also advance forwards upon the circum-
ference of the cartilage for a very short distance, and then return in loops ; they
are only found on the parts not subjected to pressure. In the foetus, the vessels
are said, by Toynbee, to advance for some distance upon the surface of the cartilage,
beneath the synovial membrane ; but Kolliker, from more recent examination,
STRUCTURE OF JOINTS. 183
doubts this. Lymphatic vessels and nerves have not, as yet, been traced in its
substance.
Fibro-cartilage is also employed, in the construction of the joints, contributing
to their strength and elasticity. It consists of a mixture of white fibrous and
cartilaginous tissues in various proportions ; it is to the first of these two consti-
tuents that its flexibility and toughness is chiefly owing, and to the latter its
elasticity. The fibro-cartilages admit of arrangement into four groups, inter-
articular, connecting, circumferential, and stratiform.
The interarticular fibro-cartilages or menisci are flattened fibro-cartilaginous
plates, of a round, oval, or sickle-like form, interposed between the articular car-
tilages of certain joints. They are free on both surfaces, thinner toward their
centre than at their circumference, and held, in position by their extremities being
connected to the surrounding ligaments. The synovial membrane of the joint is
prolonged over them a short distance from their attached margin. They are
found in the temporo-maxillary, sterno-clavicular, acromio-clavicular, wrist and
knee-joints. These cartilages are usually found in those joints most exposed to
violent concussions, 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 surface, and. give ease to the gliding movement ; to mode-
rate the effects of great pressure, and deaden the intensity of the shocks to which
they may be submitted.
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 the symphysis of the pubes ; they exist in the form of disks, intimately adhe-
rent to the opposed surfaces, being composed of concentric rings of fibrous tissue,
with cartilaginous laminae interposed, the former tissue predominating towards the
circumference, the latter towards the centre.
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 protect the edges of the bone.
The stratiform fibro-cartilages are those which form a thin layer in the osseous
grooves, through which the tendons of certain muscles glide.
Ligaments are found in nearly all the movable articulations ; they consist of
bands of various forms, serving to connect together the articular extremities of
bones, and composed mainly of bundles of white fibrous tissue placed parallel with,
or closely interlaced with, one another, and presenting a white, shining, silvery
aspect. Ligament is pliant and flexible, so as to allow of the most perfect freedom
of movement, but strong, tough, and inextensile, so as not readily to yield under
the most severely applied force ; it is, consequently, admirably adapted to serve
as the connecting medium between the bones. Some ligaments consist entirely of
yellow elastic tissue, as the ligamenta subflava, which connect together the adjacent
arches of the vertebrae, and the ligamentum nuchae. - *
Synovial Membrane is a thin, delicate membrane, arranged in the form of a
short wide tube, attached by its open ends to the margins of the articular ex-
tremities of the bones, and covering the inner surface of the various ligaments
which connect the articulating surfaces. It resembles the serous membranes in
structure, but differs from them in the nature of its secretion, which is thick,
viscid, and glairy, like the white of egg, and hence termed synovia. The synovial
membranes found in the body admit of subdivision into three kinds, articular,
bursal, and vaginal.
The articular synovial membranes are found in all the freely movable joints.
In the foetus, this membrane is said, by Toynbee, to be continued over the surface
of the cartilages ; but in the adult it is wanting, excepting at their circumference,
upon which it encroaches for a short distance : it then invests the inner surface of
the capsular or other ligaments inclosing the joint, and is reflected over the
surface of any tendons passing through its cavity, as the tendon of tha Popliteus
184 ARTICULATIONS.
in the knee, and the tendon of the Biceps in the shoulder. In most of the joints,
the synovial membrane is thrown into folds, which project into the cavity.
Some of these folds contain large masses of fat. These are especially distinct in
the hip and the knee. Others are flattened folds, subdivided at their margins into
fringe-like processes, the vessels of which have a convoluted arrangement. The
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 epithelium, and contain fat cells in variable quantity, and, more rarely,
isolated cartilage cells. They are found in most of the bursal and vaginal, as
well as in the articular synovial membranes, and were described, by Clopton
Havers, as mucilaginous glands, and as the source of the synovial secretion.
Under certain diseased conditions, similar processes are found covering the entire
surface of the synovial membrane, forming a mass of pedunculated nbro-fatty
growths, which project into the joint.
The bursse are found interposed between surfaces which move upon each other,
producing friction, as in the gliding of a tendon, or of the integument over pro-
jecting bony surfaces. ' "They admit of subdivision into two kinds, the bursse
mucosse and the synovial bursse. The former are large, simple, or irregular
cavities in the subcutaneous areolar tissue, inclosing a clear viscid fluid. They
are found in various situations, as between the integument and front of the patella,
over the olecranon, the malleoli, and other prominent parts. The synovial bursse
are found interposed between muscles or tendons as they play over projecting
bony surfaces, as between the Glutei muscles and surface of the great trochanter.
They consist of a thin wall of connective tissue, partially covered by epithelium,
and contain a viscid fluid. Where one of these exists in the neighborhood of a
joint, it usually communicates with its cavity, as is generally the case with the
bursa between the tendon of the Psoas and Iliacus, and the capsular ligament of
the hip, or the one interposed between the under surface of the Subscapularis and
the neck of the scapula.
The vaginal synovial membranes or synovial sheaths serve to facilitate the
gliding of tendons in the osseo-fibrous canals through which they pass. 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 outer surface of the con-
tained tendon ; the space between the two free surfaces of the membrane being
partially filled with 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.
Synovia is a transparent, yellowish- white, or slightly reddish fluid, viscid like
the white of egg, having an alkaline reaction, and slightly saline taste. It consists,
according to Frerichs, in the ox, of 94.85 water, 0.56 mucus and epithelium, 0.07
fat, 3.51 albumen and extractive matter, and 0.99 salts.
The Articulations are divided into three classes: Synarthrosis, or immovable
joints; Amphiarthrosis, or mixed joints; and Diarthrosis, or movable joints.
1. Synarthrosis. Immovable Articulations.
Synarthroses (avv, with, apflpoi/, a joint) or Immovable Joints include all those
articulations in which the surfaces of the bones are in almost direct contact, not
separated by an intervening synovial cavity, and immovably connected with
each other, as between the bones of the cranium and face, excepting the lower
jaw. The varieties of synarthrosis are three in number ; Sutura, Schindylesis,
and Gomphosis.
Sutura (a seam). Where the articulating surfaces are connected by a series of
processes and indentations interlocked together, it is termed sutura vera ; of which
there are three varieties, sutura dentata, sutura serrata and sutura limbosa. The
surfaces of the bones are not in direct contact, being separated by a layer of mem-
brane continuous externally with the pericranium, internally with the dura mater.
SUBDIVISION INTO THREE CLASSES. 185
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 articula-
tion 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 pro-
cesses, 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.
Where the articulation is formed by roughened surfaces placed in apposition with
one another, it is termed the false suture, sutura nolha, 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 temporo-parietal or squa-
mous suture ; and the sutura harmonia (dpuv, to adapt), 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.
Schindylesis (o^cvgvx^atj, a fissure) is that form of articulation in which a thin
plate of bone is received into a cleft or fissure formed by the separation of two
laminae of another, as in the articulation of the rostrum of the sphenoid, and
perpendicular plate of the ethmoid with the vomer, or in the reception of the latter
in the fissure between the superior maxillary and palate bones.
Gomphosis (y6(i<pos, a nail) is an articulation formed by the insertion of a conical
process into a socket, as a nail is driven into a board, and is illustrated in the
articulation of the teeth in the alveoli of the maxillary bones.
2. Amphiarthrosis. Mixed Articulations.
Amphiarthrosis (a^<j>t, on all sides, apepov, a joint) or Mixed Articulation. In this
form of articulation, the contiguous osseous surfaces are connected together by
broad flattened disks of fibro-cartilage, which adhere to the ends of both bones, as
in the articulation between the bodies of the vertebrae, and first two pieces of the
sternum ; or the articulating surfaces are covered with fibro-cartilage, partially
lined by synovial membrane, and connected together by external ligaments, as in
the sacro-iliac and pubic symphyses; both these forms being capable of limited
motion in every direction. The former resemble the synarthrodial joints in the
continuity of their surfaces, and absence of synovial sac ; the latter, the diarthro-
dial. These joints occasionally become obliterated in old age : this is frequently
the case in the interpubic articulation, and occasionally in the intervertebral and
sacro-iliac.
3. Diarthrosis. Movable Articulations.
Diarthrosis (Sta, through, apOpov, a joint). This form of articulation includes the
greater number of the joints in the body, mobility being their distinguishing
character. They are formed by the approximation of two contiguous bony sur-
faces, covered with cartilage, connected by ligaments, and lined by synovial
membrane. The varieties of joints in this class have been determined by the kind
of motion permitted in each, and are four in number: Arthrodia, Enarthrosis,
Ginglymus, Diarthrosis Rotatorius.
Arthrodia is that form of joint which admits of a gliding movement ; it is
formed by the approximation of plane surfaces, or one slightly concave, the other
slightly convex ; the amount of motion between them being limited by the liga-
ments, or osseous processes, surrounding the articulation, as in the articular
processes of the vertebras, temporo-maxillary, sterno-clavicular, and acromioclavi-
cular, inferior radio-ulnar, carpal, carpo-metacarpal, superior tibio-fibular, tarsal,
and tarso- metatarsal articulations.
Enarthrosis is that form of joint which is capable of motion in all directions.
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 liga-
ment strengthened by accessory ligamentous bands. Examples of this form of
articulation are found in the hip and shoulder.
186
ARTICULATIONS.
Ginglymus or Hinge-joint (y 177X1^6$, 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
two directions, forwards and backwards, the extent of motion at the same time
being considerable. The articular surfaces are connected together bj strong
lateral ligaments, which form their chief bond of union. The most perfect forms
of ginglymi are the elbow and ankle ; the knee is less perfect, as it allows a slight
degree of rotation in certain positions of the limb : there are also the metatarso-
phalangeal and phalangeal joints in the lower extremity, and the metacarpo-pha-
langeal and phalangeal joints in the upper extremity,
Diarthrosis rotatorius or Lateral Ginglymus. 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 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 liga-
ment : here the ring rotates round the odontoid process. In the superior radio •
ulnar articulation, the ring is formed partly by the lesser sigmoid cavity of the
ulna ; in the rest of its extent, by the orbicular ligament : here the head of the
radius rotates within the ring.
Subjoined, in a tabular form, are the names, distinctive characters, and examples
of the different kinds of articulations.
Synarthrosis or Im
movable Joint. Sur-
faces separated by
fibrous membrane, no
intervening synovial
cavity, and immova-
bly connected with
each other.
Example : bones of
the cranium and face,
except lower jaw.
S. Dentata, having
tooth-like processes.
Interparietal su •
ture.
S. Serrata, having
Sutura vera ^serrated edges, like
'(true), articulation /the teeth of a saw.
by indented bor-( Interfrontal su-
ders. \ture.
I S. Limbosa, having
/bevelled margins,
I and dentated pro-
Sutura. Arti- \ I cesses,
culation by pro- J \ Fronto-parietal su-
cesses and i ndent- / ture.
ations interlocked
together.
S. Squamosa, form-
ed by thin bevelled
margins overlapping
each other.
Sutura notha \ Temporo - parietal
(false), articulation /suture.
\by rough surfaces. \ S. Harmonia, form-
ed by the apposition
of contiguous rough
surfaces.
Intermaxillary su-
ture.
Schindylesis. Articulation formed by the reception of a
thin plate of bone into a fissure of another.
Rostrum of sphenoid with vomer.
Gomphosis. An articulation formed by the insertion of
a conical process into a socket.
Tooth in socket.
SUBDIVISION INTO THREE CLASSES. 187
/ 1. Surfaces connected by nbro-cartilage, not separated by
( synovial membrane, and having limited motion. Bodies of
a 1 mpliiarthrosis, ) vertebras.
Mixed Articulation.) 2. Surfaces covered by nbro-cartilage; lined by a partial
( synovial membrane. Sacro-iliac and pubic symphyses.
Arthrodia. Gliding joint ; articulation by plane surfaces,
which glide upon each other. As in sterno- clavicular and
acromio-clavicular articulations.
Enarthrosis. Ball-and-socket joint ; capable of motion in
lall directions. Articulation by a globular head received into
Diarthrosis, ' a cup-like cavity. As in hip and shoulder -joints.
Movable Joint. / Oinglymus. Hinge joint ; motion limited to two directions,
forwards and backwards. Articular surfaces fitted together
/so as to permit of movement in one plane. As in the elbow,
ankle, andjaiee.
Diarthrosis' rotatorius. Articulation by a pivot process
turning within a ring, or ring around a pivot. As in supe-
Vrior radio-ulnar articulation, and atlo-axoid joint.
The Kinds of Movement admitted in Joints.
The movements admissible in joints may be divided into four kinds, gliding,
angular movement, circumduction, and rotation.
Gliding movement is the most simple kind of motion that can take place in a
joint, one surface gliding over another. It is common to all movable joints ; but
in some, as in the articulations of the carpus and tarsus, is the only motion per-
mitted. This movement is not confiried to plane surfaces, but may exist between
any two contiguous surfaces, of whatever form, limited by the ligaments which
inclose the articulation.
Angular movement occurs only between the long bones, and may take place in
four directions, forwards or backwards, constituting flexion and extension, or inwards
and outwards, which constitutes abduction and adduction. Flexion and extension
are confined to the strictly ginglymoid or hinge-joints. Abduction and adduction,
combined with flexion and extension, are met with only in the most movable
joints ; as in the hip, shoulder, and metacarpal joint of the thumb, and partially
in the wrist and ankle. s
Circumduction is that limited degree of motion which takes place between the
head of a bone and its articular cavity, whilst the extremity and sides of a 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 ; and is best seen
in the shoulder and hip-joints.
Botation is the movement of a bone upon its own axis, the bone retaining the
same relative situation with respect to the adjacent parts : as in the articulation
between the atlas and axis, where the odontoid process serves as a pivot around
which the atlas turns ; or in the rotation of the radius upon the humerus, and also
in the hip and shoulder.
The articulations may be arranged into those of the trunk, those of the upper
extremity, and those of the lower extremity.
1
188 ARTICULATIONS.
ARTICULATIONS OF THE TRUNK.
These may be divided into the following groups, viz : —
I. Of the vertebral column. V. Of the ribs with the vertebras.
II. Of the atlas with the axis. VI. Of the cartilages of the ribs with
III. Of the spine with the cranium. the sternum, and with each other
1. Of the atlas with the occipital bone. VII. Of the sternum.
2. Of the axis with the occipital bone. VIII. Of the pelvis with the spine.
IV. Of the lower jaw. IX. Of the pelvis.
I. ARTICULATIONS OF THE VERTEBRAL COLUMN.
The different segments of the spine are connected together by ligaments, which
admit of the same arrangement as the vertebrae. They may be divided into five
sets. 1. Those connecting the bodies of the vertebras. 2. Those connecting the
laminae. 3. Those connecting the articular processes. 4. The ligaments con-
necting the spinous processes. 5. Those of the transverse processes.
The articulation of the bodies of the vertebras with each other forms a series of
amphiarthrodial joints ; whilst those between the articular processes form a series
of arthrodial joints.
1. The Ligaments of the Bodies.
Anterior Common Ligament. Posterior Common Ligament.
Intervertebral Substance.
The Anterior Common Ligament (fig. 116) is a broad and strong band of liga-
mentous fibres, which extends along the front surface of the bodies of the vertebras,
from the axis to the sacrum. It is broader below than above, and thicker in the
dorsal than in the cervical or lumbar regions ; it is also 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, which is con-
nected with the tendon of origin 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 prominent
margins of the vertebras, but less closely with 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 vertebras. A second subjacent set extend between
two or three vertebras; whilst a third set, the shortest and deepest, extend from
one vertebra to the next. At the sides of the bodies, this 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.
The Posterior Common Ligament is situated within the spinal canal, and
extends along the posterior surface of the bodies of the vertebras, from the body
of the axis above, where it is continuous with the occipito-axoid ligament., to the
sacrum below. It is broader at the upper than at the lower part of the spine,
and thicker in the dorsal than in the cervical or lumbar regions. In the situation
of the intervertebral substance and contiguous margins of the vertebras, 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 venae basis vertebrae. This
ligament is composed of smooth, shining, longitudinal fibres, denser and more com-
pact than those of the anterior ligament, and composed of a superficial layer
OF THE SPINE.
189
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 mater of the spinal cord by some loose filamentous tissue, very
liable to serous infiltration.
The Intervertebral Substance (fig. 116) is a lenticular disk of fibro-cartilage,
interposed between the adjacent surfaces of the bodies of the vertebrae, from the
axis to the sacrum, forming the chief bond of connection between these bones.
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 and lumbar regions, circular in the dorsal.
Their size is greatest in the lumbar region. In thinness, they vary not only in
the different regions of the spine, but in different parts of the same region : thus,
they are uniformly thick in the lumbar region ; thickest, in front, in the cervical
and lumbar regions which are convex forwards ; and behind, to a slight extent
in the dorsal region. They thus contribute, in a great measure, to the curvatures
Fig. 116. — Vertical Section of two Vertebrae and their Ligaments, from the Lumbar Region.
ANTERIOR
POSTERIOR.
COMMON
COMMON
lltf.
IICT
of the spine in the neck and loins ; whilst the concavity of the dorsal region is
chiefly due to the shape of the bodies of the vertebrae. The intervertebral disks
form about one-fourth of the spinal column, exclusive of the first two vertebrae ;
they are not equally distributed, however, between the various bones ; the dorsal
portion of the spine 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 surfaces, to the adjacent parts of the bodies of the vertebrae ; and by their
circumference are closely connected in front to the anterior, and behind to the
posterior, common ligament ; whilst, in the dorsal region, they are connected
laterally to the heads of those ribs which articulate with two vertebrae, by means
of the interarticular ligament. They, consequently, form part of the articular
cavities in which the heads of these bones are received.
The intervertebral substance is composed, at its circumference, of laminae of
fibrous tissue and fibro-cartilage ; and, at its centre, of a soft, elastic, pulpy matter.
The laminae are arranged concentrically one within the other, with their edges
190 ARTICULATIONS.
turned towards the corresponding surfaces of the vertebrae, and consist of alternate
plates of fibrous tissue and fibro- cartilage. These plates are not quite vertical in
their direction, those near the circumference being curved outwards 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 downwards ; the fibres of an
adjacent plate have an exactly opposite arrangement, varying in their direction in
every layer ; whilst in some few they are horizontal. This laminar arrangement
belongs to about the outer half of each disk, the central part being occupied by a
soft, pulpy, highly elastic substance, of a yellowish color, which rises up con-
siderably above the surrounding level, when the disk is divided horizontally.
This substance presents no concentric arrangement, and consists of white fibrous
tissue, having interspersed cells of variable shape and size. The pulpy matter,
which is especially well developed in the lumbar region, is separated from imme-
diate contact with the vertebrae, by the interposition of thin plates of cartilage.
2. Ligaments connecting the Laminae.
Ligamenta Subflava.
The Ligamenta Subflava are interposed between the laminaa of the vertebrae,
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
overlapped by the laminae. Each ligament consists of two lateral portions, which
commence on each side at the root of either articular process, and pass backwards
to the point where the laminae converge to form the spinous process, where their
margins are thickest, and separated by a slight interval, filled up with areolar
tissue. These ligaments consist of yellow elastic tissue, the fibres of which, almost
perpendicular in direction, are attached to the anterior surface of the margin of the
lamina above, and to the posterior surface, as well as to the margin, of the lamina
below. In the cervical region, they are thin in texture, but very broad and long ;
they become thicker in the dorsal region, and in the lumbar acquire very consi-
derable thickness. Their highly elastic property serves to preserve the upright
posture, and to counteract the efforts of the flexor muscles of the spine. These
ligaments do not exist between the occiput and atlas, or between the atlas and axis,
3. Ligaments connecting the Articular Process.
Capsular.
The Capsular Ligaments are thin and 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
subflava. They are longer and more loose in the cervical than in the dorsal or
lumbar regions. The capsular ligaments are lined on their inner surface by
synovial membrane.
4. Ligaments connecting the Spinous Processes.
Inter-spinous. Supra-spinous.
The Inter-spinous Ligaments, thin and membranous, are interposed between the
spinous processes in the dorsal and lumbar regions. Each ligament extends from
the root to near the summit of each spinous process, and connects together their
adjacent margins. They are narrow and elongated in the dorsal region, broader,
quadrilateral in form, and thicker in the lumbar region.
The Supraspinous Ligament is a strong fibrous cord, which connects together
the apices of the spinous processes from the seventh cervical to the spine of the
sacrum. It is thicker and broader in the lumbar than in the dorsal region, and
intimately blended, in both situations, with the neighboring aponeuroses. The
OF THE ATLAS WITH THE AXIS. 191
most superficial fibres of this ligament connect three or four vertebras; those
deeper seated pass between two or three vertebras ; whilst the deepest connect the
contiguous extremities of neighboring vertebras.
5. Ligaments connecting the Transverse Processes.
Inter-transverse.
The Inter-transverse Ligaments consist of a few thin scattered fibres, interposed
between the transverse processes. They are generally wanting in the cervical
region; in the dorsal, they are rounded cords; in the lumbar region, thin and
membranous.
Actions. The movements permitted in the spinal column are, Flexion, Exten-
sion, Lateral movement, Circumduction, and Eotation.
In Flexion or movement of the spine forwards, the anterior common ligament
is relaxed, and the intervertebral substances are compressed in front; the posterior
common ligament, the ligamenta subflava, and the inter-spinous 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 pro-
cesses glide upwards, upon the articular processes of the vertebras below. Flexion
is the most extensive of all the movements of the spine.
In Extension or movement of the spine backwards, an exactly opposite dispo-
sition 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 most free in the lower part of the lumbar, and in the
cervical regions ; extension in the latter region being greater than flexion, the
reverse of which exists in the lumbar region. These movements are least free in
the middle and upper part of the back.
In Lateral Movement, the sides of the intervertebral disks are compressed, the
extent of motion being limited by the resistance offered by the surrounding liga-
ments, and by the approximation 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 vertebras, produces great extent of move-
ment, when it takes place in the whole length of the spine, the front 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 more free in the lower part of the dorsal and lumbar
regions.
It is thus seen, that the cervical region enjoys the greatest extent of each variety
of movement, flexion and extension being very free ; lateral movement and rota-
tion, although less extensive than the former, being greater than in any other
region. In the dorsal region, especially at its upper part, the movements are most
limited ; flexion, extension, and lateral motion taking place only to a slight extent.
In the lumbar region, all the movements are very free.
II. ARTICULATION OF THE ATLAS WITH THE AXIS.
The articulation of the anterior arch of the atlas with the odontoid process forms
a lateral ginglymoid joint, whilst that between the articulating processes of the
two bones forms a double arthrodia. The ligaments of this articulation are the
Two Anterior Atlo-axoid. Transverse.
Posterior Atlo-axoid. Two Capsular.
Of the Two Anterior Atlo-axoid Ligaments (fig. 117), the most superficial is a
rounded cord, situated in the middle iine ; attached, above, to the tubercle on the
anterior arch of the atlas ; below, to the base of the odontoid process and body of
the axis. The deeper ligament is a membranous layer, attached, above, to the
192
ARTICULATIONS.
lower border of the anterior arch of the atlas ; below, to the base of the odontoid
process, and body of the axis. These ligaments are in relation, in front, with the
.Recti antici majores.
Fig. 117. — Occipito-atloid and Atlo-axoid Ligaments. Anterior View.
10 J CAPSULAR LICT It
J SYNOVIAL M EMORANS
AXOIO f CAPSULAR LICT 6c
SYNOVIAL MEMO RAN 6
Fig. 118. — Occipito-atloid and Atlo-axoid Ligaments. Posterior View.
Arch forjiaasagi ofVeTuLraZAra
&, 1t? Ct-rvical i
The Posterior Atlo-axoid Ligament (fig. 118) is a broad and thin membranous
Layer, attached, above, to the lower border of the posterior arch of the atlas ;
OF THE SPINE WITH THE CRANIUM.
193
below, to the upper edge of the lamina 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 (figs. 119 and 120) is a thick and strong ligamentous
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 backwards, broader and thicker in the middle than at either extremity, and
firmly attached on each side of the atlas to a small tubercle on the inner surface of
each of its lateral masses. As it crosses the odontoid process, a small fasciculus
is derived from its upper and lower borders ; the former passing upwards, to be
inserted into the basilar process of the occipital bone ; the latter downwards, to
Fig. 119. — Articulation between Odontoid Process and Atlas.
be attached to the root of the odontoid process : hence, this ligament has received
the name of cruciform. The transverse ligament divides the ring of the atlas into
two unequal parts : of these, the posterior and larger serves for the transmission
of the coed and its membranes ; the anterior and smaller serving to retain the
odontoid process in its position. The lower border of the space between the atlas
and transverse ligament being smaller than the upper, on account of the transverse
ligament embracing firmly the narrow neck of the odontoid process, this process
is retained in firm connection with the atlas when all the other ligaments have
been divided.
The Capsular Ligaments are two thin and loose capsules, connecting the articu-
lar surfaces of the atlas and axis, the fibres being strongest on the anterior and
external part of the articulation.
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 anterior arch of the atlas ; and one between the posterior
surface of the odontoid process and the transverse ligament. The latter often
communicates with those between the condyles of the occipital bone and the
articular surfaces of the atlas.
Actions. This joint is capable of great mobility, and allows the rotation of the
atlas, and, with it, of the cranium upon the axis, the extent of rotation being
limited by the odontoid ligaments.
III. ARTICULATION OF THE SPINE WITH THE CRANIUM.
The ligaments connecting the spine with the cranium may be divided into two
sets : 1. Those connecting the occipital bone with the atlas ; 2. Those connecting
the occipital bone with the axis.
13
194
ARTICULATIONS.
1. Articulation of the Atlas with the Occipital Bone.
This articulation is a double arthrodia. Its ligaments are the
Two Anterior Occipito-atloid.
Posterior Occipito-atloid.
Two Lateral Occipito-atloid.
Two Capsular.
Of the Two Anterior Ligaments (fig. 117), the most superficial is a strong
narrow, rounded cord, attached, above, to the basilar process of the occiput;
below, to the tubercle on the anterior arch of the atlas : the deeper ligament is a
broad and thin membranous layer, 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. This ligament is in relation, in front, with the
Recti antici minores ; behind, with the odontoid ligaments.
The Posterior Occipito-atloid Ligament (fig. 118) is a very broad but thin mem-
branous lamina, intimately blended with the dura mater. It is connected, above,
to the posterior margin of the foramen magnum; below, to the upper border 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. It is in relation, behind, with the Recti
postici minores and Obliqui superiores; in front, with the dura mater of the spinal
canal, to which it is intimately adherent.
Fig. 120. — Occipito-axoid and Atlo-axoid Ligaments. Posterior View.
He Vertical fierfitn
&/OOONTCID LIC:?
OCCIXTOI CAPSULAR LICT A
atlOiD j Synovial membrane
ATLO-f CAPSULAR LICT s,
MOID [Synovia I membrane
The Lateral Ligaments are strong fibrous bands, directed obliquely upwards
and inwards, attached, above, to the jugular process of the occipital bone; below,
to the base of the transverse process of the atlas.
The Capsular Ligaments surround the condyles of the occipital bone, and con-
dect them with the articular surfaces of the atlas ; they consist of thin and loose
capsules, which inclose the synovial membrane of the articulation. The synovial
membranes between the occipital bone and atlas communicate occasionally with
TEMPORO-MAXILLARY. 195
that between the posterior surface of the odontoid process and transverse liga-
ment.
Actions. The movements permitted in this joint are flexion and extension,
which give rise to the ordinary forward or backward nodding of the head, besides
slight lateral motion to one or the other side. When either of these actions is
carried beyond a slight extent, the whole of the cervical portion of the spine
assists in its production.
2. Articulation of the Axis with the Occipital Bone.
Occipito-axoid. Three Odontoid.
To expose these ligaments, the spinal canal should, be laid open by removing
the posterior arch of the atlas, the laminae and spinous process of the axis, and that
portion of the occipital bone behind the foramen magnum, as seen in fig. 120.
The Occipito-axoid Ligament (Apparatus ligamentosus colli) is situated at the
upper part of the front surface of the spinal canal. It is a broad and strong
ligamentous band, which covers the odontoid process and its ligaments, and appears
to be a prolongation upwards of 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.
Relations. By its anterior surface, it is intimately connected with the transverse
ligament ; by its posterior surface with the dura mater. By dividing this ligament
transversely across, and turning its ends aside, the transverse and odontoid liga-
ments are exposed.
The Odontoid or Check Ligaments are strong rounded fibrous cords, which
arise one on either side of the apex of the odontoid process, and passing obliquely
upwards and outwards, are inserted into the rough depressions on the inner side
of the condyles of the occipital bone. In the triangular interval left between these
ligaments and the margin of the foramen magnum, a third strong ligamentous
band (ligamentum suspensorium) may be seen, which passes almost perpendicularly
from the apex of the odontoid process to the anterior margin of the foramen, being
intimately blended with the anterior occipito-atloid 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.
IY. TEMPORO-MAXILLARY" ARTICULATION.
This articulation is a double arthrodia. The parts entering into its formation
are, on each side, the anterior part of the glenoid cavity of the temporal bone and
the eminentia articularis above; with the condyle of the lower jaw below. The
ligaments are the following: —
External Lateral. Stylo-maxillary.
Internal Lateral. Capsular.
Interarticular Fibro-cartilage.
The External Lateral Ligament (fig. 121) is a short, thin, and narrow fasciculus,
attached above to the outer surface of the zygoma and to the rough tubercle on
its lower border ; below, to the outer surface and posterior border of the neck
of the lower jaw. This ligament is broader above than below; its fibres are
placed parallel with one another, and directed obliquely downwards and back-
wards. Externally, it is covered by the parotid gland and by the integument.
Internally, it is in relation with the interarticular fibro-cartilage and the synovial
membranes.
196
ARTICULATIONS.
The Internal Lateral Ligament (fig. 122) is a long, thin, and loose "band,
attached above to the spinous process of the sphenoid bone, and, becoming broader
as it descends, is inserted into the inner margin of the dental foramen. Its outer
Fig. 121. — Temporo-maxillary Articulation. External View.
si
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 in-
Fig. 122. — Temporo-maxillary Articulation. Internal View. ferior dental vessels and
nerve separate it from
the ramus of the jaw.
Internally it is in rela-
tion with the Internal
pterygoid.
The Stylo-maxillary
Ligament is a thin apo-
neurotic cord, which ex-
tends 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 In-
ternal 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
law, it can only be considered as an accessory in the articulation.
TEMP ORO-M AXILLARY.
197
Articulation.
The Capsular Ligament consists of a thin and loose ligamentous capsule,
attached above to the circumference of the glenoid cavity and the articular surface
immediately in front; below, to the neck of the condyle of the lower jaw. It
consists of a few, thin scattered fibres, and can hardly be considered as a distinct
ligament ; it is thickest at the back part of the articulation.
The Interarticular fibro-cartilage (fig. 123) is a thin plate of an oval form,
placed horizontally between the condyle of the jaw and the glenoid cavity. Its
upper surface is concave from before backwards, and a little convex transversely,
to accommodate itself to the form of
the glenoid cavity. Its under sur- s*ction of Temporo-m
face, where it is in contact with the
condyle, is concave. Its circumfer-
ence is- connected externally to the
external lateral ligament, internally
to the capsular ligament ; and in front ^^ ' KSPf^^ /
to the tendon of the External ptery- ^
goid muscle. It is thicker at its cir-
cumference, especially behind, than
at its centre, where it is sometimes
perforated. The fibres of which it
is composed have a concentric ar-
rangement, more apparent at the cir-
cumference than at the centre. Its
surfaces are smooth, and divide the
joint into two cavities, each of which
is furnished with a separate synovial membrane. When the fibro-cartilage is
perforated, the synovial membranes are continuous with one another.
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 con-
tinued from the margin of the cartilage covering the glenoid cavity and eminentia
articularis, over the upper surface of the fibro-cartilage. The lower one is inter-
posed between the under surface of the fibro-cartilage and the condyle of the jaw,
being prolonged downwards a little further behind than in front.
The Nerves of this joint are derived from the auriculo-temporal, and masseteric
branches of the inferior maxillary.
Actions. The movements permitted in this articulation are very extensive.
Thus, the jaw may be depressed or elevated, or it may be carried forwards or
backwards, or from side to side. It is by the alternation of these movements
performed in succession, that a kind of rotatory movement of the lower jaw upon
the upper takes place, which materially assists in the mastication of the food.
If the movement of depression is carried only to a slight extent, the condyles
remain in the glenoid cavities, their anterior part descending only to a slight extent ;
but if depression is considerable, the condyles glide from the glenoid fossae on to
the eminentia articularis, carrying with them the interarticular fibro-cartilages.
When this movement is carried to too great an extent, as, for instance, during a
convulsive yawn, dislocation of the condyle into the zygomatic fossa occurs; the
interarticular cartilage being carried forwards, and the capsular ligament rup-
tured. When the jaw is elevated, the condyles and fibro-cartilages are carried
backwards into their original position. When the jaw is carried forwards or
backwards, a horizontal gliding movement of the fibro-cartilages and condyles
upon the glenoid cavities takes place in the antero-posterior direction j whilst in
the movement from side to side, this occurs in the lateral direction.
Y. ARTICULATION OF THE RIBS WITH THE VERTEBRAE.
The articulation 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 verte-
198
ARTICULATIONS.
Fig. 124. — Costovertebral and Costo-transverse Articulations.
Anterior View.
brae ; 2. Those which connect the neck and tubercle of the ribs with the trans-
verse processes.
1. Akticulation between the Heads of the Ribs and the Bodies
OF THE VeKTEBB^!.
These constitute a series of angular ginglymoid joints, formed by the articula-
tion of the heads of the ribs with the cavities on the contiguous margins of the
bodies of the dorsal vertebrae, connected together by the following ligaments : —
Anterior Costo- vertebral or Stellate.
Capsular.
Interarticular.
The Anterior Costo-vertebral or Stellate Ligament (fig. 124) connects the anterior
part of the head of each
rib, with the sides of the
bodies of the vertebrae,
and the intervening in-
tervertebral disk. It con-
sists of three flat bundles
of ligamentous fibres,
which radiate from the
anterior part of the head
of the rib. The superior
fasciculus passes up-
wards to be connected
with the body of the
vertebra above ; the in-
ferior one descends to
the body of the vertebra
below; and the middle
one, the smallest and
least distinct, passes ho-
rizontally inwards to be
attached to the interver-
tebral substance.
delations. 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.
In the first rib, which articulates with a single vertebra only, this ligament does
not present a distinct division into three fasciculi ; its superior fibres, however,
pass to be attached to the body of the last cervical vertebra, as well as to the
body of the vertebra with which the rib articulates. In the eleventh and twelfth
ribs, which also articulate with a single vertebra, the same division does not exist ;
but the upper fibres of the ligament, in each case, are connected with the vertebra
above, as well as to that with which the ribs articulate.
The Capsular Ligament is a thin and loose ligamentous bag, which surrounds
the joint between the head of the rib and the articular cavity formed by the junc-
tion of the vertebrae. It is very thin, firmly connected with the anterior ligament,
and most distinct at the upper and lower parts of the articulation.
The Interarticular Ligament is situated in the interior of the joint. It consists
of a short band of fibres, flattened from above downwards, attached by one extremity
to the sharp crest 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
one another, and are each lined by a separate synovial membrane. In the first.
Xju.tr SytiovtaZ
COSTO- TRANSVERSE.
199
eleventh, and twelfth ribs, the interarticular ligament does not exist; consequently,
there is but one synovial membrane.
Actions. The movements permitted in these articulations are limited to eleva-
tion, depression, and slightly forwards and backwards. This movement varies,
however, very much in its extent in different ribs. The first rib is almost entirely
immovable, excepting in deep inspiration. The movement of the second rib is
also not very extensive. In the other ribs, their mobility increases successively
to the last two, which are very movable. The ribs are generally more movable
in the female than in the male.
2. Articulation between the Neck and Tubercle of the Ribs with
the Transverse Processes.
The ligaments connecting these parts, are : —
Anterior Costo-transverse.
Middle Costo-transverse (Interosseous).
Posterior Costo-transverse.
Capsular.
The Anterior Costo-transverse Ligament (fig. 125) is a broad and strong band
of fibres, attached, below, to the sharp crest on the upper border of the neck of
each rib, and passing obliquely upwards and outwards, to the lower border of the
Fig. 125. — Costo-transverse Articulation. Seen from above.
ANTERIO* COSTO-TRANSVERSE LI C
MIDDLE COSTO-TRANSVERSE or,
INTEROSSEOUS
SYNOVIAL CAVITY
POSTERIOR COSTO-TRANSVERSE
CAPSULAR MEMBRANC
transverse process immediately above. It is broader below than above, broader
and thinner between the lower ribs than between the upper, and more distinct in
front than behind. This ligament is in relation, in front, with the intercostal
vessels and nerves; behind, with the Longissimus dorsi. Its internal border
completes an aperture formed between it and the articular processes, through
which pass the posterior branches of the intercostal vessels and nerves. Its ex-
ternal border is continuous with a thin aponeurosis, which covers the External
intercostal muscle.
The first and last ribs have no anterior costo-transverse ligament.
The Middle Costo-transverse or Interosseous Ligament consists of short, but
strong, fibres, which pass between the rough surface on the posterior part of the
200 ARTICULATIONS.
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 its fibres torn asunder.
In the eleventh and twelfth ribs, this ligament is quite rudimentary.
The Posterior Costo-transverse Ligament is a short, but thick and strong fasci-
culus, which passes obliquely from the summit of the transverse process to the
rough non-articular portion of the tubercle of the rib. This ligament is shorter
and more oblique in the upper than in the lower ribs. Those corresponding to
the superior ribs ascend, and those of the inferior ones slightly descend.
In the eleventh and twelfth ribs, this ligament is wanting.
The articular portions of the tubercle of the rib, and adjacent transverse pro-
cess, form an arthrodial joint, provided with a thin capsular ligament attached to
the circumference of the articulating surfaces, and inclosing a small synovial
membrane.
In the eleventh and twelfth ribs, this articulation is wanting.
Actions. The movement permitted in these joints is limited to a slight gliding
motion of the articular surfaces one upon the other.
VI. ARTICULATION OF THE CARTILAGES OF THE RIBS WITH THE
STERNUM.
The articulations of the cartilages of the true ribs with the sternum are arthro-
dial joints. The ligaments connecting them are : —
Anterior Costo-sternal.
Posterior Costo-sternal.
Capsular.
The Anterior Costo-sternal Ligament (fig. 126) is a broad and thin membranous
band that radiates from 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 directions. The superior fasciculi ascend obliquely, the inferior pass
obliquely downwards, and the middle fasciculi 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. This is more distinct at the lower than at the
upper part.
The Posterior Costo-sternal Ligament* 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, becom-
ing blended with the periosteum.
The Capsular Ligament surrounds the joints formed between the cartilages of
the true ribs 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.
Synovial Membranes. The cartilage of the first rib is directly continuous with
the sternum, the synovial membrane being absent. 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. That of the third rib has
also two synovial membranes; and that of the fourth, fifth, sixth, and seventh,
each a single synovial membrane. Thus there are eight synovial cavities in the
articulations between the costal cartilages of the true ribs and the sternum. They
COSTO-STERNAL AND INTERCOSTAL.
201
may be demonstrated by removing a thin section from the anterior surface of the
sternum and cartilages, as seen in fig. 126. After middle life, the articular
surfaces lose their polish, become 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 firmly united to the sternum. The cartilage of the seventh
Fig. 126. — Costo^sternal, Costo-xiphoid, and Intercostal Articulations. Anterior View.
The eynovidl cavities expoted
by a vcrUcal section, {f the Sternum k Cxrtuageff
continuous with SttmuMr
1 NTCR-ARTICU IAR 1 1 C !
two iSynovva,LmemoraneS
Single Synovial
Membrane
rib, and occasionally also that of the sixth, is connected to the anterior surface of
the ensiform appendix, by a band of ligamentous fibres, which varies in length
and breadth in different subjects. It is called the costo-xiphoid ligament.
Actions. The movements which are permitted in the costo-sternal articulations
are limited to elevation and depression ; and these only to a slight extent
;
202 ARTICULATIONS.
Articulation of the Cartilages of the Ribs with each other.
The cartilages of the sixth, seventh, and eighth ribs articulate, by their lower
borders, with the corresponding margin of the adjoining cartilages, by means of a
small, smooth, oblong-shaped facet. Each articulation is inclosed in a thin
capsular ligament, lined by synovial membrane, and strengthened externally and
internally by ligamentous fibres (intercostal ligaments), which pass from one
cartilage to the other. Sometimes the cartilage of the fifth rib, 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 found
wanting.
Articulation of the Ribs with their Cartilages.
The outer extremity of each costal cartilage is received into a depression in the
sternal end of the ribs, and held together by the periosteum.
Fig. 127. — Articulations of Pelvis and Hip. Anterior View.
Jihirim-r of eomnumieukon
Jiurstt of PSOAS Ml. ILIACLJ
VII. LIGAMENTS OF THE STERNUM.
The first and second pieces of the Sternum are united by a layer of cartilage
which rarely ossifies, except at an advanced period of life. These two segments
are connected by an anterior and posterior ligament.
The anterior sternal ligament consists of a layer of fibres, having a longitudinal
direction; it blends with the fibres of the anterior costo-sternal ligaments on
both sides, and with the aponeurosis of origin of the Pectoralis major. This
ligament is rough, irregular, and much thicker at the lower than at the upper part
of the bone.
SACRO-ILIAC.
203
The posterior sternal ligament is disposed in a somewhat similar manner on ths
posterior surface of the articulation.
VIII. ARTICULATIONS OF THE PELVIS WITH THE SPINE.
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 downwards of the anterior and posterior common ligaments. 2. The
intervertebral substance connecting the flattened oval surfaces of the two bones,
thus 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-spinous and supra-spinous ligaments.
The two proper ligaments connecting the pelvis with the spine are the lumbo-
sacral and lumbo-iliac.
The Lumbosacral Ligament (fig. 127) is a short, thick, triangular fasciculus,
connected above to the lower and front part of the transverse process of the last
lumbar vertebra, and, passing obliquely outwards, is attached below to the lateral
Fig. 128. — Articulations of Pelvis and Hip. Posterior View.
surface of the base of the sacrum, becoming blended with the anterior sacro-iliac
ligament. This ligament is in relation in front with the Psoas muscle.
The Lumbo-iliac Ligament (fig. 127) passes horizontally outwards from the
apex of the transverse process of the last lumbar vertebra, to that portion of 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 externally. It is
in relation, in front, with the Psoas muscle ; behind, with the muscles occupying
the vertebral groove ; above, with the Quadratus lumborum.
204 ARTICULATIONS.
IX. 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.
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. The surfaces of these cartilages in the adult are rough
and irregular, and separated from one another by a soft yellow pulpy substance.
At an early period of life, occasionally in the adult, and in the female during
pregnancy, they are smooth and lined by a delicate synovial membrane. The
ligaments connecting these surfaces are the anterior and posterior sacro-iliac.
The Anterior Sacro-iliac Ligament consists of numerous thin ligamentous bands,
which connect the anterior surfaces of the sacrum and ilium.
The Posterior Sacro-iliac (fig. 128) is a strong interosseous ligament, situated
in the deep depression between the sacrum and ilium behind, and forming the
chief bond of connection between these 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, nearly horizontal in direction, arise from the first
and second transverse tubercles 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 ex-
tremity to the third or fourth transverse tubercle on the posterior surface of the
sacrum, and by the other to the posterior superior spine of the ilium ; it is some-
times called the oblique sacro-iliac ligament.
2. Articulation of the Sacrum and Ischium.
The Great or Posterior Sacro-sciatic .
The Lesser or Anterior Sacro-sciatic.
The Great or Posterior Sacro-sciatic Ligament is situated at the lower and back
part of the pelvis. It is thin, 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 third and fourth transverse tubercles on the sacrum, and to
the lower part of the lateral margin of that bone and the coccyx; passing
obliquely downwards, outwards, and forwards, 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 forwards along the inner margin of the ramus forming
the falciform ligament. The free concave edge of this ligament 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 towards the perineum, the
other towards the Obturator internus muscle.
The posterior surface of this ligament gives origin, by its whole extent, to fibres
of the Gluteus maximus. Its anterior surface is united to the lesser sacro-sciatic
ligament. Its superior border forms the lower boundary of the lesser sacro-sciatic
foramen. Its lower border forms part of the boundary of the perineum. This
ligament is pierced by the coccygeal branch of the sciatic artery.
The Lesser or Anterior Sacro-sciatic Ligament, 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
which its fibres are intermingled.
SACRO-COCCYGEAL. 205
It is in relation, anteriorly, with the Coccygeus muscle ; posteriorly, it is covered
by the posterior ligament, and crossed by the pudic vessels and nerve. Its supe-
rior border forms the lower boundary of the great sacro-sciatic foramen ; its infe-
rior border, part of the lesser sacro-sciatic foramen.
These two ligaments convert the sacro-sciatic notches into foramina. The
superior or great sacro-sciatic foramen is bounded, in front and above, by the pos-
terior border of the os innominatum ; behind, by the great sacro-sciatic ligament ;
and below, by the lesser ligament. It is partially filled up, in the recent state,
by the Pyriformis muscle. Above this muscle, the gluteal vessels and nerve
emerge from the pelvis ; and below it, the ischiatic vessels and nerves, the internal
pudic vessels and nerve, and the nerve to the Obturator internus. The inferior
or lesser sacro-sciatic foramen is bounded, in front, by the tuber ischii ; above, by
the spine and lesser ligament; behind, by the greater ligament. It transmits
the tendon of the Obturator internus muscle, its nerve, and the pudic vessels and
nerve.
3. Articulation of the Sacrum and Coccyx.
This articulation is an amphiarthrodial joint, formed between the oval surface
on the summit of the sacrum, and the base of the coccyx. It is analogous to the
joints between the bodies of the vertebrae, and is connected by similar ligaments.
They are the —
Anterior Sacro-coccygeal.
Posterior Sacro-coccygeal.
Interarticular Fibro-cartilage.
The Anterior Sacro-coccygeal Ligament consists of a few irregular fibres, which
descend from the anterior surface of the sacrum to the front of the coccyx, becom-
ing blended with" the periosteum.
The Posterior Sacro-coccygeal Ligament is a flat band of ligamentous fibres, 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 liga-
ment completes the lower and back part of the sacral canal. Its superficial fibres
are much longer than the deep-seated ; the latter extend from the apex of the
sacrum to the upper cornua of the coccyx. This ligament is in relation in front
with the arachnoid membrane of the sacral canal, a portion of the sacrum, and
almost the whole of the posterior surface of the coccyx ; behind with the Gluteus
maximus.
An Interarticular 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 more firm in texture. It is
somewhat thicker in front and behind, than at the sides. Occasionally a synovial
membrane is found where the coccyx is freely movable, which is more especially
the case during pregnancy.
The different segments of the coccyx are connected together by an extension
downwards 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 the
coccyx.
Actions. The movements which take place between the sacrum and coccyx,
and between the different pieces of the latter bone, are slightly forwards and back-
wards ; they are very limited. Their mobility increases during pregnancy.
4. Articulation of the Pubes.
The articulation between the pubic bones is an amphiarthrodial joint, formed
206
ARTICULATIONS.
by the junction of the two oval surfaces which has received the name of the
symphysis. The ligaments of this articulation are the —
Anterior Pubic. Posterior Pubic.
Superior Pubic. Subpubic.
Interarticular Fibro-cartilage.
The Anterior Pubic Ligament 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 forming an interlacement with the
fibres of the aponeurosis of the External oblique muscle. The deep fibres pass
transversely across the symphysis, and are blended with the interarticular fibro-
cartilage.
The Posterior Pubic Ligament consists of a few thin, scattered fibres, which unite
the two pubic bones posteriorly.
The Superior Pubic Ligament is a band of fibres, which connects together the
two pubic bones superiorly.
The Subpubic Ligament is a thick, triangular arch of ligamentous fibres, con-
necting 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, with the rami of the pubes. Its fibres are of a yellowish color, closely
connected, and have an arched direction.
Fig. 129. — Vertical Section of the Symphysis Pubis.
Made near its Posterior Surface.
Two Flhro-Cartilaginoiis plates
In.twmejlia.te elaeUc tissue
Synovial cavity at upper &■ haek part
The Interarticular Fibro-cartilage consists of two oval-shaped plates, one cover-
ing the surface of each symphysis pubis. They vary in thickness in different
subjects, and project somewhat beyond the level of the bones, especially behind.
The outer surface of each plate is firmly connected to the bone by a series of
nipple-like processes, which accurately fit within corresponding depressions on the
osseous surface. Their opposed surfaces are connected, in the greater part of their
extent, by an intermediate fibrous elastic tissue ; and by their circumference to the
various ligaments surrounding the joint. An interspace is left between the plates
at the upper and back part of the articulation, where the fibrous tissue is deficient,
and the surface of the fibro-cartilage is lined by epithelium. The space is found
at all periods of life, both in the male and female ; but it is larger in the latter,
especially during pregnancy, and after parturition. 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 cartilages. This structure may be easily
demonstrated, by making a vertical section of the symphysis pubis near its pos-
terior surface.
STERNO-CLAVICULAR.
207
The Obturator Ligament is a dense membranous layer, consisting of fibres which
interlace in various directions. It is attached to the circumference of the obtu-
rator foramen, which it closes completely, except at its upper and outer part,
where a small oval canal is left for the passage of the obturator vessels and nerve.
It is in relation, in front, with the Obturator externus ; behind, with the Obtura-
tor internus ; both of which muscles are in part attached to it.
ARTICULATIONS OF THE UPPER EXTREMITY.
The articulations of the Upper Extremity may be arranged into the following
groups: — 1. Sterno-clavicular articulation. 2. Scapuloclavicular articulation.
3. Ligaments of the Scapula. 4. Shoulder-joint. 5. Elbow-joint. 6. Radio-
ulnar articulation. 7. Wrist-joint. 8. Articulations of the Carpal bones. 9.
Carpo-metacarpal articulations. 10. Metacarpo-phalangeal articulations. 1L
Articulations of the Phalanges.
Fig. 130. — Sterno-clavicular Articulation. Anterior View.
1. Sterno-clavicular Articulation.
The Sterno-clavicular is an arthrodial joint. The parts entering into its forma-
tion 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 clavicle is much longer than that of the sternum, and invested with a layer
of cartilage,1 which is considerably thicker than that on the latter bone. The
ligaments of this joint are the
Anterior Sterno-clavicular. Interclavicular.
Posterior Sterno-clavicular. Costo-clavicular or rhomboid.
Interarticular Fibro-Cartilage.
The Anterior Sterno-clavicular Ligament is a broad band of ligamentous fibres,
which covers the anterior surface of the articulation, being attached, above, to the
upper and front part of the inner extremity of the clavicle ; and, passing obliquely
downwards and inwards, is attached, below, to the front and upper part of the
first piece of the sternum. This ligament is covered in front by the sternal por-
1 According to Bruch, the sternal end of the clavicle is covered by a tissue which is more
fibrous than cartilaginous in structure.
208 ARTICULATIONS.
tion of the Sterno-cleido-mastoid and the integument; behind, it is in relation
with the interarticular fibro-cartilage and the two synovial membranes.
The Posterior Sternoclavicular Ligament is a broad band of fibres, which covers
the posterior surface of the articulation, being attached, above, to the posterior
part of the inner extremity of the clavicle ; and, passing obliquely downwards
and inwards, is connected, below, to the posterior and upper part of the sternum.
It is in relation, in front, with the interarticular fibro-cartilage and synovial mem-
branes ; behind, with the Sterno-hyoid and Sterno-thyroid muscles.
The Interclavicular Ligament is a flattened ligamentous band, which varies
considerably in form and size in different individuals ; it passes from the upper
part of the inner extremity of one clavicle to the other, and is closely 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 is a short, flat, and strong band of
ligamentous fibres of a rhomboid form, attached, below, to the upper and inner
part of the cartilage of the first rib ; and, ascending obliquely backwards and out-
wards, 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 is a flat and nearly circular disk, interposed
between the articulating surfaces of the sternum and clavicle. It is attached,
above, to the upper and posterior border 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 ligaments. It is thicker at the circum-
ference, 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 ; when the fibro-cartilage is perforated, which not unfrequently
occurs, the synovial membranes communicate.
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 more loose
of the two ; they seldom contain much synovia.
Actions. This articulation is the centre of the movements of the shoulder, and
admits of motion in nearly every direction, upwards, downwards, backwards,
forwards, as well as circumduction ; the sternal end of the clavicle and the inter-
articular cartilage gliding on the articular surface of the sternum.
2. Scapuloclavicular Articulation".
The Scapuloclavicular is an arthrodial joint, formed between the outer ex-
tremity of the clavicle, and the upper edge of the acromion process of the scapula.
Its ligaments are the
Superior Acromio-clavicular.
Inferior Acromio-clavicular.
n t . i I Trapezoid.
(Joraco-clavicular < n r.,
( Conoid.
Interarticular Fibro-cartilage.
The Superior Acromio-clavicular Ligament is a broad band of fibres, of a quad-
rilateral form, 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 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 interarticular fibro-cartilage and synovial membranes.
The Inferior Acromio-clavicular Ligament, somewhat thinner than the preceding,
covers the under part of the articulation, and is attached to the adjoining surfaces
SCAPULOCLAVICULAR.
209
of the two bones. It is in relation, above, with the interarticular fibro-cartilage
(when it exists) and the synovial membranes; below, with the tendon of the
Supra-spinatus. These two ligaments are continuous with each other in front
and behind, and form a complete capsule around the joint.
The Coraco -clavicular Ligament serves to connect the clavicle with the coracoid
process of the scapula. It consists of two fasciculi, called the trapezoid and conoid
ligaments.
The Trapezoid ligament, the anterior and external lasciculus, is a broad, thin,
quadrilateral-shaped band of fibres, placed obliquely between the coracoid process
aud the clavicle. It is attached, below, to the upper surface of the coracoid
Fig. 131.-
-The Lett Shoulder-joint, Scapuloclavicular Articulations,
and Proper Ligaments of Scapula-
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, the posterior and internal fasciculus, is a dense band of
fibres, conical in form, the base being turned upwards, the summit downwards.
It is attached by its apex to a rough depression at the base of the coracoid process,
internal to the preceding ; above, by its expanded base, to the conoid tubercle on
the under surface of the clavicle, and into a line proceeding internally from it
for half an inch. These ligaments are in relation, in front, with the Subclavius;
behind, with the Trapezius : they serve to limit rotation of the scapula forwards
and backwards.
The Interarticular Fibro-cartilage is most frequently absent in this articulation.
When it exists, it generally only partially separates the articular surfaces, and
14
210 ARTICULATIONS.
occupies the upper part of the articulation. More rarely, it completely separates
the joint into two cavities.
There are two Synovial Membranes where a complete interarticular cartilage
exists ; more frequently, there is only one synovial membrane.
Actions. The movements of this articulation are of two kinds, x. A gliding
motion of the articular end of the clavicle on the acromion. 2. Rotation of the
scapula forwards and backwards upon the clavicle, the extent of this rotation being
limited by the two portions of the coraco-clavicular ligament.
3. Proper Ligaments of the Scapula.
The proper ligaments of the scapula are, the
Coraco-acromial. Transverse.
The Coraco-acromial Ligament is a broad, thin, flat band, of a triangular shape,
extended transversely above the upper part of the shoulder-joint, between the
coracoid and acromion 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 obliquely backwards and outwards, its anterior fibres trans-
versely. 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 ; below, with the tendon of the
Supra-spinatus muscle, a bursa being interposed. Its anterior border is continuous
with a dense cellular lamina that passes beneath the Deltoid upon the tendons of
the Supra-spinati and Infra-spinati muscles.
The Transverse or Coracoid Ligament converts the suprascapular 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 ; its accompanying vessels above it.
4. Shoulder-joint.
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 strong ligaments and tendons which surround it, and above by an
arched vault, formed by the under surface 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 observed in the glenoid cavity. Its liga-
ments are the
Capsular. Coraco-humeral.
Glenoid.
The Capsular Ligament 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 than below,
remarkably loose and lax, and 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 external surface is strengthened, above, by the Supra-
spinatus ; above and internally, by the coraco-humeral ligament ; below, by the
long head of the Triceps ; externally, by the tendons of the Infra-spinatus and
ELBOW-JOINT. 211
Teres minor ; and internally, by the tendon of the Subscapularis. The capsular
ligament usually presents three openings ; one at its inner side, below the coracoid
process, partially filled up by the tendon of the Subscapularis ; it establishes a
communication between the synovial membrane of the joint and a bursa beneath
the tendon of that muscle ; a second, not constant, at its outer part, where a com-
munication sometimes exists between the joint and a bursal sac belonging to the
Infra-spinatus muscle. The third is seen in the lower border of the ligament,
between the two tuberosities, for the passage of the tendon of the Biceps muscle.
The Coraco-humeral or Accessory Ligament is a broad band which strengthens
the upper and inner part of the capsular ligament. It arises from the outer border
of the coracoid process, and descends obliquely downwards and outwards to the
front of the great tuberosity of the humerus, being blended with the tendon of the
Supra-spinatus muscle. This ligament is intimately united to the capsular in the
greater part of its extent.
The Glenoid Ligament is a firm fibrous band attached round the margin of
the glenoid cavity. It is triangular on section, the thickest portion being fixed to
the circumference of the cavity, the free edge being thin and sharp. It is con-
tinuous above with the long tendon of the Biceps muscle, which bifurcates at the
upper part of the cavity into two fasciculi, which encircle its margin, and unite
at its lower part. This ligament deepens the cavity for articulation, and protects
the edges of the bone. It is lined by the synovial membrane.
The Synovial Membrane lines the margin of the glenoid cavity and 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 neck of the humerus, and
is continued a short distance over the cartilage covering the head of this bone. The
long tendon of the Biceps muscle which passes through the joint is inclosed in a
tubular sheath of synovial membrane, which is reflected upon it at the point where
it perforates the capsule, and is continued around it as far as the summit of the
glenoid cavity. The tendon of the Biceps is thus enabled to traverse the articu-
lation, but is not contained in the interior of the synovial cavity. The synovial
membrane communicates with a large bursal sac beneath the tendon of the Sub-
scapularis, by an opening at the inner side of the capsular ligament; it also
occasionally communicates with another bursal sac, beneath the tendon of the
Infra-spinatus, through an orifice at its outer part. A third bursal sac, which
does not communicate with the joint, is placed between the under surface of the
deltoid and the outer surface of the capsule.
The Muscles in relation with the joint are, above, the Supra-spinatus ; below,
the long head of the Triceps ; internally, the Subscapularis ; externally, the Infra-
spinatus, and Teres minor; within, the long tendon of the Biceps. The Deltoid
is placed most externally, and covers the articulation on its outer side, and in front
and behind.
The Arteries supplying the joint are articular branches of the anterior and
posterior circumflex, and suprascapular.
The Nerves are derived from the circumflex and suprascapular.
Actions. The shoulder-joint is capable of movement in almost any direction,
forwards, backwards, abduction, adduction, circumduction, and rotation.
5. Elbow-joint.
The Elbow is a ginglymoid or hinge joint. The bones entering into its forma-
tion are the trochlear surface of the humerus, which is received in the greater
sigmoid cavity of the ulna, and admits of the movements peculiar to this joint,
those of flexion and extension, whilst the cup-shaped depression of the head of the
radius articulates with the radial tuberosity of the humerus, its circumference
with the lesser sigmoid cavity of the ulna, allowing of the movement of rotation of
the radius on the ulna, the chief action of the superior radio-ulnar articulation.
212
ARTICULATIONS.
The articular surfaces are covered with a thin layer of cartilage, and connected
together by the following ligaments : —
Anterior Ligament. Internal Lateral.
Posterior Ligament.
External Lateral.
The Anterior Ligament (fig. 132) is a broad and thin fibrous layer, which covers
the anterior surface of the joint
Fig. 132.— Left Elbow-Joint, showing Ante-
rior and Internal Lateral Ligaments.
It is attached to the front of the humerus
immediately above the coronoid fossa;
below, to the anterior surface of the
coronoid process of the ulna and orbicu-
lar ligament, being continuous on each
side with the lateral ligaments. Its super-
ficial or oblique fibres pass from the inner
condyle of the humerus outwards to the
orbicular ligament. The middle fibres,
vertical in direction, pass from the upper
part of the coronoid depression, and
become blended with the preceding. A
third, or transverse set, intersect these at
right angles. This ligament is in relation,
in front, with the Brachialis anticus;
behind, with the synovial membrane.
The Posterior Ligament is a thin and
loose membranous fold, attached, above,
to the lower end of the humerus, imme-
diately above the olecranon depression ;
below, to the margin of the olecranon.
The superficial or transverse fibres pass
between the adjacent margins of the ole-
cranon fossa. The deeper portion consists
of vertical fibres, which pass from the
upper part of the olecranon fossa to the
margin of the olecranon. This ligament
is in relation, behind, with the tendon of
the Triceps and Anconeus ; in front, with
the synovial membrane.
The Internal Lateral Ligament is a
thick triangular band of ligamentous
fibres, consisting of two distinct portions,
an anterior and posterior. The anterior
portion, directed obliquely forwards, is
attached, above, by its apex, to the front
part of the internal condyle of the humerus ; and, below, by its broad base, to the
inner margin of the coronoid process. The posterior 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. This ligament is in rela-
tion, internally, with the Triceps and Flexor carpi ulnaris muscles, and the ulnar
nerve.
The External Lateral Ligament (fig. 133) is a short and narrow fibrous fasci-
culus, less distinct than the internal, attached, above, to 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
brevjs muscle.
The Synovial Membrane is very extensive. It covers the margin of the arti-
cular surface of the humerus, and lines the coronoid and olecranon depressions on
that bone; from these points, it is reflected over the anterior, posterior, and lateral
RADIO-ULNAR.
213
ligaments, and forms a pouch between Fig. 133.-Left Elbow-Joint showing Tosterior
,o , ' • -i -i xi • i. i and External Lateral Ligaments.
the lesser sigmoid cavity, the internal
surface of the annular ligament, and the
circumference of the head of the radius.
The Muscles in relation with the joint
are, in front, the Brachialis anticus;
behind, the Triceps and Anconeus; ex-
ternally, the Supinator brevis, and the
common tendon of origin of the Extensor
muscles; internally, the common tendon
of origin of the Flexor muscles, the
Plexor carpi ulnaris, and ulnar nerve.
The Arteries supplying the joint are de-
rived from the communicating branches
between the superior profunda, inferior
profunda, and anastomotic branches 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 ; and a few filaments
from the musculo-cutaneous.
Actions. The elbow is one of the most
perfect hinge-joints in the body ; its move-
ments are, consequently, limited to flexion
and extension, the exact apposition of
the articular surfaces preventing the least
lateral motion.
6. Radioulnar Articulations.
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. They may,
consequently, be subdivided into three sets : 1, the superior radio-ulnar ; 2, the
middle radio-ulnar ; and 3, the inferior radio-ulnar articulations.
1. Superior Radio-ulnar Articulation.
This articulation is a lateral ginglymoid joint. The bones entering into its for-
mation are the inner side of the circumference of the head of the radius, which
rotates within the lesser sigmoid cavity of the ulna. These surfaces are covered
with cartilage, and invested with a duplicature of synovial membrane, continuous
with that which lines the elbow-joint. Its only ligament is
The Annular or Orbicular.
The Orbicular Ligament (fig. 133) 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 three-fourths of a fibrous ring
attached by each end to the extremities of the sigmoid cavity, and is broader at the
upper part of its circumference than below, by which means the head of the radius
is more securely held in its position. Its outer surface is strengthened by the ex-
ternal lateral ligament of the elbow, and affords partial origin to the Supinator
brevis muscle. Its inner surface is smooth, and lined by synovial membrane.
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
214 ARTICULATIONS.
lesser sigmoid cavity of the ulna ; rotation forwards being called pronation ; rota-
tion backward, supination.
2. Middle Radioulnar Articulation.
The interval between the shafts of the radius and ulna is occupied by two liga-
ments.
Oblique. Interosseous.
The Oblique or Round Ligament (fig. 132) is a small round fibrous cord, which
extends obliquely downwards and outwards, from the tubercle of the ulna at the
base of the coronoid 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 is a broad and thin plane of aponeurotic fibres,
descending obliquely downwards and inwards, from the interosseous ridge on the
radius to that on the ulna. It is deficient above, commencing about an inch be-
neath 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 border and the oblique ligament an interval
exists, through which the posterior interosseous vessels pass. Two or three fibrous
bands are occasionally found on the posterior surface of this membrane, which
descend obliquely from the ulna towards 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 (radial margin) with the Flexor longus pollicis (ulnar margin),
with the Flexor profundus digitorum, 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 metacarpi pollicis,
Extensor primi internodii pollicis, Extensor secundi internodii pollicis, Extensor
indicis ; and, near the wrist, with the anterior interosseous artery and posterior
interosseous nerve.
3. Inferior Radio-ulnar Articulation.
This is a lateral ginglymoid joint, formed by the head of the ulna being received
into the sigmoid cavity at the inner side of the lower end of the radius. The
articular surfaces are covered by a thin layer of cartilage, and connected together
by the following ligaments.
Anterior radio-ulnar.
Posterior radio-ulnar.
Triangular Interarticular Fibro-cartilage.
The Anterior Radio-ulnar Ligament (fig. 134) is a narrow band of fibres, ex-
tending 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. 135) extends between similar points
on the posterior surface of the articulation.
The Triangular Fibro-cartilage (fig. 136) is placed transversely beneath the
head of the ulna, binding the lower end of this bone and the radius firmly together.
Its circumference is thicker than its centre, which is thin and occasionally per-
forated. 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 the radius, which separates the sigmoid cavity from
the carpal articulating surface. Its margins are united to the ligaments of the
wrist-joint. Its upper surface, smooth and concave, is contiguous with the head
of the ulna ; its tinder surface, also concave and smooth, with the cuneiform bone.
Both surfaces are lined by a synovial membrane : the upper surface, by one peculiar
RADIO-TTLNAR.
215
to the radioulnar articulation ; the under surface, by the synovial membrane of
the wrist.
Fig. 134. — Ligaments of "Wrist and Hand. Anterior View.
NFERIOR RADIO-ULNAR ARTICJ
WRIST-JOINT
CARPAL ARTICf?
CARPO-METACARPAL ARTIC •«
The Synovial Membrane of this articulation has been called, from its extreme
looseness, the membrana sacciformis ; it covers the margin of the articular surface
of the head of the ulna and where reflected from this bone on to the radius forms
Fig. 135. — Ligaments of Wrist and Hand. Posterior View.
Inferior
Hadio -ulnar Artie
~Wrl*t- Joint
Carpal Artio7^
Carpo-M^etaearpal /SpS;
ArtieV*
a very loose cul-de-sac ; from the radius, it is continued over the upper surface
of the fibro-cartilage. The quantity of synovia which it contains is usually
216 ARTICULATIONS.
considerable. When the fibro-cartilage is perforated, the synovial membrane is
continuous with that which lines the wrist.
Actions. The movement which occurs in the inferior radio-ulnar articulation is
just the reverse of that which takes place between the two bones above ; it is
limited to rotation of the radius round the head of the ulna ; rotation forwards
being termed pronation, rotation backwards supination. In pronation, the sigmoid
cavity glides forward on the articular edge of the ulna ; in supination, it rolls in
the opposite direction, the extent of these movements being limited by the anterior
and posterior ligaments.
7. Wrist-joint.
The Wrist presents most of the characters of an enarthrodial joint. The parts
entering into its formation are, the lower end of the radius, and under surface of
the triangular interarticular fibro-cartilage, above ; and the scaphoid, semilunar,
and cuneiform bones below. The articular surfaces of the radius and interarticular
fibro-cartilage form a transversely elliptical concave surface. The radius is sub-
divided into two parts by a line extending from before backwards ; and these,
together with the interarticular cartilage, form three facets, one for each carpal
bone. The three carpal bones are connected together, and form a convex surface,
which is received into the concavity above mentioned. All the bony surfaces of
the articulation are covered with cartilage, and connected together by the follow-
ing ligaments.
External Lateral. Anterior.
Internal Lateral. Posterior.
The External Lateral Ligament 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 is a rounded cord, attached, above, to the ex-
tremity of the styloid process of the ulna ; below, it divides 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 Ligament is a broad membranous band, consisting of three fasci-
culi, attached, above, to the anterior margin of the lower end of the radius, its
styloid process, and the ulna; its fibres pass downwards and inwards, to be
inserted into the palmar surface of the scaphoid, 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 Ligament, less thick and strong than the anterior, is attached,
.above, to the posterior border of the lower end of the radius ; its fibres descend
obliquely downwards and inwards to be attached to the dorsal surface of the
scaphoid, semilunar, and cuneiform bones, its fibres 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 synovial membrane of the
wrist.
The Synovial Membrane lines the under surface of the triangular interarticular
fibro-cartilage above ; and is reflected on the inner surface of the ligaments above
mentioned.
Relations. The wrist-joint is covered in front by the flexor, and behind by the
extensor tendons ; 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.
Actions. The movements permitted in this joint are flexion, extension, abduc-
OF THE CARPUS. 217
tion, adduction, and circumduction. ' It is totally incapable of rotation, one of the
characteristic movements in true enarthrodial joints.
8. Articulations of the Carpus.
These articulations may be subdivided into three sets : —
1. The articulation of the first row of carpal bones.
2. The articulation of the second row of carpal bones.
3. The articulation of the two rows with each other.
1. Articulation of the First Row of Carpal Bones.
These are arthrodial joints. The articular surfaces are covered with cartilage
and connected together by the following ligaments : —
Two Dorsal. Two Palmar.
Two Interosseous.
The Dorsal Ligaments, two in number, are placed transversely behind the
bones of the first row ; they connect the scaphoid and semilunar, and the semilunar
and cuneiform.
The Palmar Ligaments, also two in number, connect the scaphoid and semi-
lunar, and the semilunar and cuneiform bones ; they are less strong than the dorsal,
and placed very deep under the anterior ligament of the wrist.
The Interosseous Ligaments (fig. 135) are two narrow bundles of fibrous tissue,
connecting the semilunar bone, on one side with the scaphoid, on the other with
the cuneiform. They close the upper part of the interspaces between the scaphoid,
semilunar, and cuneiform bones, their upper surfaces being smooth, and lined by
the synovial membrane of the wrist-joint.
The articulation of the pisiform with the cuneiform is provided with a separate
synovial membrane, protected by a thin capsular ligament. There are also two
strong fibrous fasciculi, which connect this bone to the unciform, and base of the
fifth metacarpal bone.
2. Articulation of the Second Row of Carpal Bones.
These are arthrodial joints, the articular surfaces are covered with cartilage,
and connected by the following ligaments : —
Three Dorsal. Three Palmar.
Two Interosseous.
The three Dorsal Ligaments extend transversely from one bone to another on
the dorsal surface, connecting the trapezium with the trapezoid, the trapezoid with
the os magnum, and the os magnum with the unciform.
The three Palmar Ligaments have a similar arrangement on the palmar surface.-
The two Interosseous Ligaments, much thicker than those of the first row, are
placed one on each side of the os magnum, connecting it with the trapezoid exter-
nally, and the unciform internally. The former is less distinct than the latter.
3. Articulation of the Two Rows of Carpal Bones with each other.
The articulation between the two rows of the carpus consists of an enarthrodial
joint in the middle, formed by the reception of the os magnum into a cavity
formed by the scaphoid and semilunar bones, and of an arthrodial joint on each
side, the outer one formed by the articulation of the scaphoid with the trapezium
and trapezoid, the internal one by the articulation of the cuneiform and unciform.
The articular surfaces are covered by a thin layer of cartilage, and connected by
the following ligaments : —
Anterior or Palmar. External Lateral.
Posterior or Dorsal. Internal Lateral.
218 ARTICULATIONS.
The Anterior or Palmar Ligaments consist of short fibres, which pass obliquely
between the bones of the first and second row on the palmar surface.
The Posterior or Dorsal Ligaments have a similar arrangement 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.
There are two Synovial Membranes found in the articulation of the carpal
bones with each other. The first of these, the more extensive, lines the under
surface of the scaphoid, semilunar, and cuneiform bones, sending upwards two
prolongations between their contiguous surfaces; it is then reflected over the
bones of the second row, and sends down three prolongations between them, which
line their contiguous surfaces, and invest the carpal extremities of the four outer
metacarpal bones. The second is the synovial membrane between the pisiform
and cuneiform bones.
Actions. The partial movement which takes place between the bones of each
row is very inconsiderable ; the movement between the two rows is more marked,
but limited chiefly to flexion and extension.
9. Carpo-metacarpal Articulations.
Articulation of the Metacarpal Bone of the Thumb with the Trapezium.
This is an enarthrodial joint. Its ligaments are a capsular and synovial mem-
brane. The capsular ligament is a thick but loose capsule, which passes from
the circumference of the upper extremity of the metacarpal bone, to the rough
edge bounding the articular surface of the trapezium ; it is thickest externally
and behind, and lined by a separate synovial membrane.
Articulation of the Metacarpal Bones of the Fingers with the Carpus.
The joints formed between the carpus and four inner metacarpal bones are
connected together by dorsal, palmar, and interosseous ligaments.
The Dorsal Ligaments, the strongest and most distinct, connect the carpal and
metacarpal bones on their dorsal surface. The second metacarpal bone receives
two fasciculi, one from the trapezium, the other from the trapezoid ; the third
metacarpal receives 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.
The Palmar Ligaments 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 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.
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 (fig. 136) are thus seen to be five in
number. The first, the membrana sacciformis, lining the lower end of the ulna,
the sigmoid cavity of the radius, and upper surface of the triangular interarticular
fibro-cartilage. The second lines the lower end of the radius and interarticular
fibro-cartilage above, and the scaphoid, semilunar, and cuneiform bones below. The
third, the most extensive, covers the contiguous surfaces of the two rows of carpal
CARPO-MET A CARPAL.
219
bones, and, passing between the bones of the second range, lines the carpal extre-
mities of the four inner metacarpal bones. The fourth lines the adjacent
surfaces of the trapezium and metacarpal bone of the thumb. And the fifth the
adjacent surfaces of the cuneiform and pisiform bones.
Actions. The movement permitted in the carpo-metacarpal articulations 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
thumb with the trapezium is most movable, then the fifth metacarpal, and then
the fourth. The second and third are almost immovable. In the articulation of
the metacarpal bone of the thumb with the trapezium, the movements permitted
are flexion, extension, adduction, abduction, and circumduction.
Fig. 136.
-Vertical Section through the Articulations at the Wrist, showing the five Synovial
Membranes.
Articulations of the Metacarpal Bones with each other.
The carpal extremities of the metacarpal bones articulate with one another at
each side by small surfaces covered with cartilage, and connected together by
dorsal, palmar, and interosseous ligaments.
The Dorsal and Palmar Ligaments pass transversely from one bone to another
on the dorsal and palmar surfaces. The Interosseous Ligaments pass between
their contiguous surfaces, just beneath their lateral articular facets.
The Synovial Membrane lining the lateral facets is a reflection from that
between the two rows of carpal bones.
The digital extremities of the metacarpal bones are connected together by a
narrow fibrous band, the transverse ligament, which passes transversely across
their under surfaces, and is blended with the ligaments of the metacarpophalan-
geal articulations. Its anterior surface presents four grooves for the passage of
the flexor tendons. , Its posterior surface blends with the ligaments of the meta-
carpophalangeal articulation.
220
ARTICULATIONS.
LATERAL LICAMENT
Metacurpo -jihala. n/jeal
Artie*!
10. Metacarpophalangeal Articulations (fig. 137).
These articulations are of the ginglymoid kind, formed by the reception of the
rounded head of the metacarpal bone, into a superficial cavity in the extremity
of the first phalanx. They are connected by the following ligaments : —
Anterior. Two Lateral.
The Anterior Ligaments are thick, dense, and fibro-cartilaginous in texture.
Each is placed on the palmar
Fig. l37.-Articulations of the Phalanges. surface of the joint, in the
interval between the lateral
ligaments, to which they are
connected ; they are loosely
united to the metacarpal bone,
but very firmly to the base of
the first phalanges. Their
palmar surface is intimately
blended with the transverse
ligament, each ligament form-
ing with it a groove for the
passage of the flexor tendons,
the sheath surrounding which
is connected to it at each side.
By their internal surface, they
form part of the articular
surface for the head of the
metacarpal bone, and are lined
by a synovial membrane.
The Lateral Ligaments are
strong rounded cords, placed
one on each side of the joint,
each being attached by one
extremity to the tubercle on
the side of the head of the
metacarpal bone, and by the
other to the contiguous ex-
tremity of the phalanx.
The Posterior Ligament is
supplied by the extensor ten-
don placed over the back of
each joint.
Actions. The movements
which occur in these joints
are flexion, extension, adduc-
tion, abduction, and circumduction ; the lateral movements are very limited.
11. Articulations of the Phalanges (fig. 137).
These are ginglymoid joints, connected by the following ligaments : —
Anterior. Two Lateral.
The arrangement of these ligaments is similar to those in the metacarpo-pha-
langeal 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
extensive, but extension is limited by the anterior and lateral ligaments.
FJi&lantfeal
Artie Vf
HIP-JOINT.
221
ARTICULATIONS OP THE LOWER EXTREMITY.
The articulations of the Lower Extremity comprise the following groups. 1.
The hip-joint. 2. The knee-joint. 3. The articulations between the tibia and
fibula. 4. The ankle-joint. 5. The articulations of the tarsus. 6. The tarso-
metatarsal articulations. 7. The metatarso-phalangeal articulations. 8. The
articulation of the phalanges.
1. Hip-joint (fig. 138).
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, being deficient in the situation of the circular depression at the
bottom of this cavity. The ligaments of the joint are the
Capsular. Teres.
Ilio-femoral. Cotyloid.
Transverse.
Fig. 138. — Left Hip-joint laid open.
The Capsular Ligament is a strong, dense, ligamentous capsule, embracing the
margin of the acetabulum above, and surrounding the neck of the femur below.
Its upper circumference is attached to the acetabulum two or three lines external
to the cotyloid ligament ; but, opposite the notch where the margin of this cavity
is deficient, it is connected with 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 inter-trochanteric line ;
above, to the base of the neck ; behind, to the middle of the neck of the bone,
about half an inch from the posterior inter-trochanteric line. It is much thicker
222 • ARTICULATIONS.
at the upper and fore part of the joint where the greatest amount of resistance is
required, than below where it is thin, loose, and longer than in any other situation.
Its external surface is rough, covered by numerous muscles, and separated in front
from the Psoas and Iliacus by a synovial bursa, which not unfrequently commu-
nicates 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.
The llio-femoral Ligament (fig. 127) is an accessory band of fibres, extending
obliquely across the front of the joint: it is intimately connected with the capsular
ligament, and serves to strengthen it in this situation. It is attached, above, to the
anterior inferior spine of the ilium ; below, to the anterior intertrochanteric line.
The Ligamentum Teres is a triangular band of fibres, 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, which consists of two bundles of fibres, into the margins of
the notch at the bottom of the acetabulum, becoming blended with the transverse
ligament. It is formed of a bundle of fibres, the thickness and strength of which
are very variable, surrounded by a tubular sheath of synovial membrane. Some-
times, the synovial fold only exists, or the ligament may be altogether absent.
The use of the round ligament is to check rotation outwards, when combined with
flexion : it thus assists in preventing dislocation of the head of the femur forwards
and outwards, an accident likely to occur from the necessary mechanism of the joint,
if not provided against by this ligament and the thick anterior part of the capsule.1
The Cotyloid Ligament is a fibro -cartilaginous rim attached to the margin of
the acetabulum, the cavity of which it deepens ; at the same time it protects the
edges of the bone, and fills up the inequalities on its surface. It is prisnioid in
form, its base being attached to the margin of the acetabulum, its opposite edge
being free and sharp ; whilst its two surfaces are invested by synovial membrane,
the external one being in contact with the capsular ligament, the internal one
being inclined inwards so as to narrow the acetabulum and embrace the cartila-
ginous 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 is a strong flattened band of fibres, which crosses the
notch at the lower part of the acetabulum, and converts it into a foramen. It is
continuous at each side with the cotyloid ligament. An interval is left beneath
the ligament for the passage of nutrient vessels to the joint.
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 this point it is reflected on the
internal surface of the capsular ligament, covers both surfaces of the cotyloid
ligament, and the mass of fat contained in the fossa at the bottom of this cavity,
and is prolonged in the form of a tubular sheath around the ligamentum teres,
as far as the head of the femur.
The Muscles in relation with the joint are, in front, the Psoas and Iliacus, sepa-
rated from the capsular ligament by a synovial bursa ; above, the short head of
the Rectus and Gluteus minimus, the latter being closely adherent to it ; internally,
the Obturator externus and Pectineus ; behind, the Pyriformis, Gemellus superior,
Obturator internus, Gemellus inferior, Obturator externus, and Quadratus femoris.
The Arteries supplying it are derived from the obturator, sciatic, internal cir-
cumflex, and gluteal.
The Nerves are articular branches from the sacral plexus, great sciatic, obtu-
rator, and accessory obturator nerves.
Actions. The movements of the hip, like all enarthrodial joints, are very exten-
sive; they are, flexion, extension, adduction, abduction, circumduction, and rotation.
1 See an interesting paper, "On the Use of the Round Ligament of the Hip-joint," by Dr. J.
Struthers. Edinburgh Medical Journal, 1858.
223
are, the condyles of the femur above, the head of the tibia below, and the patella
in front. The articular surfaces are covered with cartilage, and connected toge-
ther by ligaments, some of which are placed on the exterior of the joint, whilst
others occupy its interior.
KNEE-JOINT.
2. Knee-joint.
External Ligaments.
Anterior or Ligamentum Pa-
tellae.
Posterior or Ligamentum
Posticum Winslowii.
Internal Lateral.
Two External Lateral.
Capsular.
Internal Ligaments.
Anterior or External Crucial.
Posterior or Internal Crucial.
Two Semilunar Fibro-cartilages.
Transverse.
Coronary.
Ligamentum mucosum.
Ligamenta alaria.
The Anterior Ligament cr Ligamentum Patellse (fig. 139) is that portion of
the common tendon of the extensor muscles of the thigh which is continued from
Fig. 139.— Right Knee-joint. Anterior "View. Fig. 140.— Right Knee-joint. Posterior View.
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 tuberosity of the tibia ; its superficial fibres being continu-
ous across the front of the patella with those of the tendon of the Quadriceps ex-
tensor. Two synovial bursas are connected with this ligament and the patella ; one
is interposed between the patella and the skin covering its anterior surface ; the
224 ARTICULATIONS.
other, of small size, between the ligamentum patellae and the upper part of the
tuberosity of the tibia. The posterior surface of this ligament is separated above
from the knee-joint by a large mass of adipose tissue ; its lateral margins are con-
tinuous with the aponeuroses derived from the Vasti muscles.
The Posterior Ligament or Ligamentum, Posticum Winslowii (fig. 140) is a broad,
flat, fibrous band, which covers over the whole of the back part of the joint. It
consists of two lateral portions, formed chiefly of vertical fibres, which arise above
from the condyles of the femur, and are connected below with the back part of
the head of the tibia, being closely united with the tendons of the Gastrocnemius,
Plantaris, and Popliteus muscles ; the central portion is formed of fasciculi ob-
liquely directed and separated from one another by apertures for the passage of
vessels. The strongest of these fasciculi is derived from the tendon of the Semi-
membranosus ; it passes from the back part of the inner tuberosity of the tibia,
obliquely upwards and outwards, to the back part of the outer condyle of the
femur. The posterior ligament forms part of the floor of the popliteal space, and
upon it rests the popliteal artery.
The Internal Lateral Ligament is a broad, flat, membranous band, thicker behind
than in front, and situated 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 aponeurosis of the Sartorius, and the tendons
of the Gracilis and Semi-tendinosus muscles, a synovial bursa being interposed.
Its deep surface covers the anterior portion of the tendon of the Semi-membra-
nosus, the synovial membrane of the joint, and the inferior internal articular
artery ; it is intimately adherent to the internal semilunar fibro-cartilage.
The Long External Lateral Ligament is a strong, rounded, fibrous cord, situated
nearer to the back than the front of the joint. It is attached, above, to the outer
condyle 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 into two
parts, separated by the ligament, at its insertion. It has, passing beneath it,
the tendon of the Popliteus muscle, and the inferior external articular vessels and
nerve.
The Short External Lateral Ligament is an accessory bundle of fibres, placed
behind and parallel with the preceding ; attached, above, to the lower part of the
outer condyle 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.
The Capsular Ligament consists of an exceedingly thin, but strong, fibrous
membrane, which fills in the intervals left by the preceding ligaments. It is
attached to the femur immediately above its articular surface ;' below, to the upper
border and sides of the patella, the margins of the head of the tibia and inter-
articular cartilages, and is continuous behind with the posterior ligament. This
membrane is strengthened by fibrous expansions, derived from the fascia lata, from
the Vasti and Crureus muscles, and from the Biceps, Sartorius, and tendon of the
Sami-membranosus.
The Crucial are two interosseous 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 and posterior, from the position of their
attachment to the tibia.
The Anterior or External Crucial Ligament (fig. 141), smaller than the poste-
rior, is attached to the inner side of 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 upwards, backwards, and outwards, is inserted
into the inner and back part of the outer condyle of the femur.
The Posterior or Internal Crucial Ligament is Larger in size, but less oblique
v.\ its direction than the anterior. It is attached to the back part of the depres-
KNEE-JOINT.
225
Fig. 141. — Right Knee-joint. Showing Internal
Ligaments.
sion behind the spine of the tibia, and to the posterior extremity of the external
semilunar fibro-cartilage ; passing upwards, forwards, and inwards, it is inserted
into the outer and fore part of the inner condyle of the femur. As it crosses the
anterior crucial ligament, a fasciculus is
given off from it, which blends with its
posterior part. It is in relation, in front,
with the anterior crucial ligament; behind,
with the ligamentum posticum Winslowii.
The Semilunar Fibro-cartilages (fig.
142) are two crescentic lamellae attached
to the margins of the head of the tibia,
serving to deepen its surface for articula-
tion with the condyles of the femur. The
circumference of each cartilage is thick
and convex ; the inner free border, thin
and concave. 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, the inner third being
uncovered ; both surfaces are smooth, and
invested by synovial membrane.
The Internal Semilunar Fibro-cartilage
is nearly semicircular in form, a little
elongated from before backwards, and
broader behind than in front ; its convex
border is united to the internal lateral
ligament, and to the head of the tibia,
by means of the coronary ligaments^ its
anterior extremity, thin and pointed, is
firmly implanted into a depression in front
of the inner articular surface of the tibia;
its posterior extremity to the depression behind the spine, between the attach-
ment of the external cartilage and posterior crucial ligament.
The External Semilunar Fibro-cartilage 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 Pop-
liteus muscle. Its circumference is held
in connection with the head of the tibia,
by means of the coronary ligaments;
and its two extremities are firmly im-
planted in the depressions in front and
behind the spine of the tibia. These ex-
tremities, at their insertion, are interposed
between the attachments of the internal
cartilage. The external semilunar fibro-
cartilage gives off from its anterior bor-
der a fasciculus, which forms the trans-
verse ligament. By its anterior extremity, it is continuous with the anterior
crucial ligament. Its posterior extremity divides into three slips ; two of these
pass upwards and forwards, and are inserted into the outer side of the inner
condyle, one in front, the other behind the posterior crucial ligament ; the third
fasciculus is inserted into the back part of the anterior crucial ligament.
The Transverse Ligament is a band of fibres, which passes transversely be-
15
Fig. 142.— Head of Tibia, with Semilnnai
Cartilages, etc. Seen from above.
Right Side.
226 ARTICULATIONS.
tween the anterior convex margin of the external semilunar cartilage, to the
anterior extremity of the internal cartilage ; its thickness varies considerably in
different subjects.
The Coronary Ligaments consist of numerous short fibrous bands, which con-
nect the convex border of the semilunar cartilages with the circumference of the
head of the tibia, and with the other ligaments surrounding the joint.
The Synovial Membrane of the knee-joint is the largest and most extensive in
the body. Commencing at the upper border of the patella, it forms a large cul-
de-sac beneath the Extensor tendon of the thigh : this is sometimes replaced by a
synovial bursa interposed between the tendon and the front of the femur, which
in some subjects communicates with the synovial membrane of the knee-joint, by
an orifice of variable size. 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 ; and, beneath the patella, it is separated from the
anterior ligament by a considerable quantity of -adipose tissue. In this situation,
it sends off a triangular-shaped prolongation, containing a few ligamentous fibres,
which extends from the anterior part of the joint below the patella, to the front
of the intercondyloid notch. This fold has been termed the ligamentum mucosum.
The ligamenta alaria consist of two fringe-like folds, which extend from the sides
of the ligamentum mucosum, upwards and outwards, to the sides of the patella.
The synovial membrane invests the semilunar fibro-cartilages, and on the back
part of the external one forms a cul-de-sac between the groove on its surface and
the tendon of the Popliteus ; it is continued to the articular surface of the tibia,
surrounds the crucial ligaments, and the inner surface of the ligaments which
inclose the joint ; lastly, it approaches the condyles of the femur, and from them is
continued on to the lower part of the front of the shaft. 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 it.
The Arteries supplying the joint are derived from the anastomotic branch of
the femoral, articular branches of the pqrjliteal, and recurrent branch of the
anterior tibial.
The Nerves are derived from the obturator, anterior crural, and external and
internal popliteal.
Actions. The chief movements of this joint are flexion aud extension ; but it is
also capable of performing some slight rotatory movement. During flexion, the
articular surfaces of the tibia, covered by their interarticular cartilages, glide
backwards upon the condyles of the femur, the lateral, posterior, and crucial liga-
ments are relaxed, the ligamentum patella? is put upon the stretch, the patella
filling up the vacuity in front of the joint between the femur and tibia. In
extension, the tibia and interarticular cartilages glide forwards upon the femur;
all the ligaments are stretched, with the exception of the ligamentum patellae,
which is relaxed, and admits of considerable lateral movement. The movement
of rotation is permitted when the knee is semi-flexed, rotation outwards being
most extensive.
3. Articulation between the Tibia and Fibula.
The articulations between the tibia and fibula are effected by ligaments which
connect both extremities, as well as the shaft of these bones. They may, con-
sequently, be subdivided into three sets. 1. The Superior Tibio-fibular articula-
tion. 2. The Middle Tibio-fibular articulation. 3. The Inferior Tibio-fibular
articulation.
1. Superioe Tibio-fibular Articulation.
This articulation is an arthrodial joint. The contiguous surfaces of the bode."
TIBIO-FIBULAR. 227
present two flat oval surfaces covered with, cartilage, and connected together by
the following ligaments.
Anterior Superior Tibio-fibular.
Posterior Superior Tibio-fibular.
The Anterior Superior Ligament (fig. 141) consists of two or three broad and
flat bands, which pass obliquely upwards and inwards, from the head of the fibula
to the outer tuberosity of the tibia.
The Posterior Superior Ligament is a single thick and broad band, which
passes from the back part of the head of the fibula to the back part of the outer
tuberosity of the tibia. It is covered in by the tendon of the Popliteus muscle.
A Synovial Membrane lines this articulation. It is occasionally continuous
with that of the knee-joint at its upper and back part.
2. Middle Tibio-fibular Articulation".
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
pass between the interosseous ridges on the two bones. It is broader above than
below, and presents at its upper part a large oval aperture for the passage of the
anterior tibial artery forwards to the anterior aspect of the leg ; and at its lower
part, an opening for the passage of the anterior peroneal vessels. It is continuous
below with the inferior interosseous ligament ; and is perforated in numerous parts
for the passage of small vessels. It is in relation in front with the Tibialis anticus,
Extensor longus digitorum, Extensor proprius pollicis, Peroneus tertius, and the
anterior tibial vessels and nerve ; behind, with the Tibialis posticus and Flexor
longus pollicis.
3. Inferior Tibio-fibular Articulation.
This articulation is formed by the rough convex surface at the inner side of
the lower end of the fibula, being connected with a similar 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. Its ligaments are —
Inferior Interosseous. Posterior Inferior Tibio-fibular.
Anterior Inferior Tibio-fibular. Transverse.
The Inferior Interosseous Ligament consists of numerous short, strong fibrous
bands, which pass between the contiguous rough surfaces of the tibia and fibula,
constituting the chief bond of union between these bones. It is continuous, above,
with the interosseous membrane.
The Anterior Inferior Ligament (fig. 144) is a flat triangular band of fibres,
broader below than above, which extends obliquely downwards and outwards
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, smaller than the preceding, is disposed in a
similar manner on the posterior surface of the articulation.
The Transverse Ligament is a long narrow band of ligamentous fibres, con-
tinuous with the preceding, passing transversely across the back of the joint,
from the external malleolus to the tibia, a short distance from its malleolar process.
This ligament projects below the margins of the bones, and forms part of the
articulating surface for the astragalus.
The Synovial Membrane lining the articular surfaces is derived from that of
the ankle-joint.
228
ARTICULATIONS.
Actions. The movement permitted in these articulations is limited to a very
slight gliding of the articular surfaces one upon another.
4. Ankle-joint.
^ The Ankle is a ginglymoid or hinge-joint. The bones entering into its forma-
tion are the lower extremity of the tibia and its malleolus, and the malleolus of
the fibula, above, which, united, form an arch, in which is received the upper
convex surface of the astragalus and its two lateral facets. These surfaces are
covered with cartilage, and connected together by the following ligaments : —
Anterior. Internal Lateral.
External Lateral.
The Anterior Ligament (fig. 143) is a broad, thin, membranous layer, attached
above, to the margin of the articular surface of the tibia ; below, to the margin of
Fig. 143. — Ankle-joint : Tarsal and Tarso-metatarsal Articulations. Internal View. Right bide.
T»S30- MCTATAR
ANTIC ?!
TARSAL ARTI C
the astragalus, in front of its articular surface. It is in relation, in front, with
the Extensor tendons of the toes, 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 Internal Lateral or Deltoid Ligament consists of two layers, superficial
and deep. The superficial layer 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 forwards to be inserted into the scaphoid ; the middle descend
almost perpendicularly to be inserted into the os calcis ; and the posterior fibres
pass backwards and outwards to be attached to the inner side of the astragalus.
The deep layer consists of a short, thick, and strong fasciculus which passes
from the apex of the malleolus to the inner surface of the astragalus, below the
articular surface. This ligament is covered in by the tendons of the Tibialis
posticus and Flexor longus digitorum muscles.
The External Lateral Ligament (fig. 144) consists of three fasciculi, taking
different directions, and separated by distinct intervals.
ANKLE-JOINT.
229
The anterior fasciculus, the shortest of the three, passes from the anterior margin
of the summit of the external malleolus, downwards and forwards, to the astra-
galus, in front of its external articular facet.
The posterior fasciculus, the most deeply seated, passes from the depression at the
inner and back part of the external malleolus to the astragalus, behind its external
malleolar facet. Its fibres are almost horizontal in direction.
The middle fasciculus, the longest of the three, is a narrow rounded cord, pass-
ing from the apex of the external malleolus downwards and slightly backwards
to the middle of the outer side of the os calcis. It is covered by the tendons of
the Peroneus longus and brevis. There is no posterior ligament, its place being
supplied by the transverse ligament of the tibia and fibula.
The Synovial Membrane invests the inner surface of the ligaments, and sends
a duplicature upwards between the lower extremities of the tibia and fibula for a
short distance.
Fig. 144. — Ankle-joint : Tarsal and Tarso- metatarsal Articulations. External View. Right Side.
NFERIOR TlBlO-FlBULAf*
ARTIES
ANKLE-JOINT
TARSAL ARTIC"?
TARSO-METATARSAL ARTIC55
Relations. The tendons, vessels, and nerves in connection with the joint are,
in front, from within outwards, the Tibialis anticus, Extensor proprius pollicis,
anterior tibial vessels, anterior tibial nerve, Extensor communis digitorum, and
Peroneus tertius ; behind, from within outwards, Tibialis posticus, Flexor longus
digitorum, posterior tibial vessels, posterior tibial nerve, Flexor longus pollicis,
and, in the groove behind the external malleolus, the tendons of the Peroneus
longus and Peroneus brevis.
The Arteries supplying the joint are derived from the malleolar branches of
the anterior tibial and peroneal.
The Nerves are derived from the anterior tibial.
Actions. The movements of the joint are limited to flexion and extension.
There is no lateral motion.
5. Articulations of the Tarsus.
These articulations may be subdivided into three sets : 1. The articulation of
the first row of tarsal bones. 2. The articulation of the second row of tarsal
bones. 3. The articulations of the two rows with each other.
230 ARTICULATIONS.
1. Articulation of the First Eow of Tarsal Bones.
The articulation between the astragalus and os calcis is an arthrodial joint
connected together by three ligaments : —
External Calcaneo-astragaloid. Posterior Calcaneo-astragaloid.
Interosseous.
The External Calcaneo-astragaloid Ligament (fig. 144) is a short, strong fasci-
culus, passing from the outer surface of the astragalus, immediately beneath its
external malleolar facet, to the outer edge 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 Posterior Calcaneo-astragaloid Ligament (fig. 143) connects the posterior
extremity of the astragalus with the upper contiguous surface of the os calcis ; it
is a short narrow band, the fibres of which are directed obliquely backwards and
inwards.
The Interosseous Ligament forms the chief bond of union between these bones.
It consists of numerous vertical and oblique fibres, attached, by one extremity,
to the groove between the articulating surfaces 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.
The Synovial Membranes (fig. 146) are two in number ; one for the posterior
calcaneo-astragaloid articulation; a second for the anterior calcaneo-astragaloid
joint. The latter synovial membrane is continued forwards between the contigu-
ous surfaces of the astragalus and scaphoid bones.
2. Articulations of the Second Row of Tarsal Bones.
The articulations between the scaphoid, cuboid, and three cuneiform are effected
by the following ligaments : —
Dorsal. Plantar.
Interosseous.
The Dorsal Ligaments are small bands of parallel fibres, which pass from each
bone to the neighboring bones with which it articulates.
The Plantar Ligaments have the same arrangement on the plantar surface.
The Interosseous Ligaments are four in number. They consist of strong trans-
verse fibres, which pass between the rough non-articular surfaces of adjoining
bones. There is one between the sides of 'the scaphoid and cuboid ; a second
between the internal and middle cuneiform bones ; a third between the middle and
external cuneiform ; and a fourth between the external cuneiform and cuboid.
The scaphoid and cuboid, when in contact, present each a small articulating facet,
covered with cartilage, and lined either by a separate synovial membrane, or by
an offset from the common tarsal synovial membrane.
3. Articulations of the Two Rows of the Tarsus with each other.
These articulations may be conveniently divided into three sets. ] . The arti-
culation of the os calcis' with the cuboid. 2. The os calcis with the scaphoid.
3. The astragalus with the scaphoid.
1. The ligaments connecting the os calcis with the cuboid are four in number : —
j. , j Superior Calcaneo-cuboid.
.Dorsal. -j jnterna] Calcaneo-cuboid or Interosseous.
•p, j Long Calcaneo-cuboid.
riantar. < ghort Calcaneo-cuboid.
OF THE TARSUS.
23J
The Superior Calcaneo-cuboid Ligament (fig. 144) is a thin and narrow fasci-
culus, which passes between the contiguous surfaces of the os calcis and cuboid,
on the dorsal surface of the joint.
The Internal Calcaneo-cuboid or Interosseous Ligament (fig. 144) is a short, but
thick and strong, band *of fibres, arising from the os calcis, in the deep groove
which intervenes between it and the astragalus; being closely blended, at its ori-
gin, with the superior calcaneo-scaphoid ligament. It 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 row of the tarsus.
The Long Calcaneo-cuboid (fig. 145), F%- 145. -Ligaments of Plantar Surface of the
the most superficial of the two plantar
ligaments, is the longest of all the liga-
ments of the tarsus, being attached to the
under surface of the os calcis, from near
the tuberosities, as far forwards as the
anterior tubercle ; its fibres pass forwards
to be attached to the ridge on the under
surface of the cuboid bone, the more su-
perficial fibres being continued onwards
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 Ligament
lies nearer to the bones than the preceding,
from which it is separated by a little areo-
lar adipose tissue. It is exceedingly
broad, about an inch in length, and ex-
tends from the tubercle and the depression
in front of it on the fore part of the under
surface of the os calcis, to the inferior sur-
face of the cuboid bone behind the peroneal
groove. A synovial membrane is found in
this articulation.
2. The ligaments connecting the os
calcis with the scaphoid, are two in num-
ber:—
Superior Calcaneo-scaphoid.
Inferior Calcaneo-scaphoid.
The Superior Calcaneo-scaphoid (fig. 144) arises, as already mentioned, with the
internal calcaneo-cuboid, in the deep groove between the astragalus and os calcis ;
it passes forward from the inner side 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 Calcaneo-scaphoid (fig. 145) is by far the largest and strongest of
the two ligaments of this articulation ; it is a broad and thick band of ligamentous
fibres, which passes forwards and inwards from the anterior and inner extremity
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 supports the head of the
astragalus, forming part of the articular cavity in which it is received. Its upper
surface is lined by the synovial membrane continued from the anterior calcaneo-
astragaloid articulation. Its under surface is in contact with the tendon of the
Tibialis posticus muscle.
232
ARTICULATIONS.
3. The articulation between the astragalus and scaphoid is an enarthrodial
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 calcaneo-scaphoid ligament, which fills up
the triangular interval between these bones. The only •ligament of this joint is
the superior astragalo-scaphoid, a broad band of ligamentous fibres, which passes
obliquely forwards 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 supplies the place of an inferior liga-
ment.
The Synovial Membrane which lines the joint is continued forwards from the
anterior calcaneo-astragaloid articulation. This articulation permits of consider-
able mobility ; but its feebleness is such as to occasionally allow of dislocation
of the astragalus.
The Synovial Membranes (fig. 146) found in the articulations of the tarsus are
four in number : one for the posterior calcaneo-astragaloid articulation ; a second
for the anterior calcaneo-astragaloid and astragalo-scaphoid articulations ; a third
Fig. 146.
-Oblique Section of the Articulations of the Tarsus and Metatarsus.
Showing the Six Synovial Membranes.
for the calcaneo-cuboid articulation; and a fourth for the articulations between
the scaphoid and the three cuneiform, the three cuneiform 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. The prolongation which lines
the metatarsal bones passes forwards between the external and middle cuneiform
bones. A small synovial membrane is sometimes found between the contiguous
surfaces of the scaphoid and cuboid bones.
Actions. The movements permitted between the bones of the first row, the
astragalus and os calcis, are limited to a gliding upon each other from before
backwards, and from side to side. The gliding movement which takes place
between the bones of the second row is very slight, the articulation between the
scaphoid and cuneiform bones being more movable than those of the cuneiform
with each other and with the cuboid. The movement which takes place between
the two rows is more extensive, and consists in a sort of rotation, by means of
which the sole of the foot may be slightly flexed, and extended, or carried inwards
and outwards.
TARSO-METATARSAL. 233
6. Takso-metatarsal Articulations.
These are arthrodial joints. The bones entering into their formation are the
internal, middle, external cuneiform, and cuboid, which articulate with the meta-
tarsal 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 in-
ternal and external cuneiform, resting against the middle cuneiform, and being the
most strongly articulated of all the metatarsal bones ; the third metatarsal articu-
lates with the extremity of the external cuneiform ; 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 the following ligaments : —
Dorsal. Plantar.
Interosseous.
The Dorsal Ligaments 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 ; and the fourth and fifth have one each from the cuboid.
The Plantar Ligaments consist of longitudinal and oblique fibrous bands con-
necting 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 receive strong fibrous bands, which pass obliquely
across from the internal cuneiform ; the plantar ligaments of the fourth and fifth
consist of a few scanty fibres derived from the cuboid.
The Interosseous Ligaments are three in number : internal, middle, and external.
The internal one 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.
The Synovial Membranes of these articulations are three in number : one for
the metatarsal bone of the great toe, with the internal cuneiform ; one for the second
and third metatarsal bones, with the middle and external cuneiform, which is
continuous with the great tarsal synovial membrane ; and one for the fourth and
fifth metatarsal bones with the cuboid. The synovial membranes of the tarsus
and metatarsus are thus seen to be six in number (fig. 146).
i
Articulations of the Metatarsal Bones with each other.
The bases of the metatarsal bones, except the first, are connected together by
dorsal, plantar, and interosseous ligaments. The dorsal and plantar ligaments
pass from one metatarsal bone to another. The interosseous ligaments lie deeply
between the rough non-articular portions of their lateral surfaces. The articular
surfaces are covered with cartilage, and provided with synovial membrane, con-
tinued forwards from the tarso-metatarsal joints. The digital extremities of the
metatarsal bones are united by the transverse metatarsal ligament. It connects
the great toe with the rest of the metatarsal bones ; in this respect it differs from
the transverse ligament in the hand.
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 ; considerable
motion, however, takes place in their digital extremities.
Metatarsophalangeal Articulations.
The heads of the metatarsal bones are connected with the concave articular
surfaces of the first phalanges by the following ligaments : —
Anterior or Plantar. Two Lateral.
234 ARTICULATIONS.
They are arranged precisely similar to the corresponding parts in the hand.
The expansion of the Extensor tendon supplies the place of a posterior ligament.
Actions. The movements permitted in the metatarso-phalangeal articulations
are flexion, extension, abduction, and adduction.
Akticulation of the Phalanges.
The ligaments of these articulations are similar to those found in the hand ;
each pair of phalanges being connected by an anterior or plantar and two lateral
ligaments, and their articular surfaces lined by synovial membrane. Their actions
are also similar.
For further information on this subject, the Student is referred to Cruveilhier's "Anatomie
Descriptive ;" to Mr. Humphry's able work on the " Human Skeleton, including the Joints ;"
and to Arnold's " Tabulae Anatomicse," Fascic. 4. Pars 2, " Icones articulorum et ligamentorum.''
On the textures composing the Joints refer to Todd and Bowman's " Physiological Anatomy,"
and Kblliker's " Manual of Human Microscopic Anatomy."
The Muscles and Fasciae.
The Muscles are the active organs of locomotion. They are formed of bundles
of reddish fibres, consisting chemically of fibrine, and endowed with the pro-
perty of contractility. Two kinds of muscular tissue are found in the animal
body, viz., that of voluntary or animal life, and that of involuntary or organic
life.
The muscles of animal life {striped muscles) are capable of being either exerted
or controlled by the efforts of the will. They are composed of bundles of fibres
inclosed in a delicate web of areolar tissue. Each bundle consists of numerous
smaller ones, inclosed in a similar fibro-areolar covering, and these again of primi-
tive fasciculi.
The primitive fasciculi consist of a number of filaments, inclosed in a tubular
sheath of transparent, elastic, and apparently homogeneous membrane, named by
Bowman the " Sarcolemma." The primitive fasciculi are cylindriform or prismatic.
Their breadth varies in man from 5^ to 5^ of an inch, the average of the ma-
jority being about ^11 ; their length is not always in proportion to the length of
the muscle, but depends on the arrangement of the tendons. This form of muscular
fibre is especially characterized by being apparently marked with very fine, dark,
parallel lines or strise, which pass transversely round them, in curved or wavy
parallel lines, from t^^tt to j^^s °f an mcn apart. Other striae pass longitu-
dinally over the tubes, indicating the direction of the primitive fibrils of which
the primitive fasciculus is composed. They are less distinct than the former.
The primitive fibrils constitute the proper contractile tissue of the muscle.
Each fibril is cylindriform, somewhat flattened, about th^tttf oi> an inch m thick-
ness, and marked by transverse strise placed at the same distance from each other
as the striae on the surface of the fasciculus. Each fibril apparently consists of a
single row of minute particles, named " sarcous elements" by Bowman, connected
together like a string of beads. Closer examination, however, shows that the
elementary particles are little masses of pellucid substance, having a rectangular
outline, and appearing dark in the centre. These appearances would favor the
suggestion that the elementary particles of which the fibrils are composed are
possibly nucleated cells, cohering in a linear series, the transverse marks between
them corresponding to their line of junction. Kolliker, however, considers "the
sarcous elements as artificial products, occasioned by the breaking up of the fibrils
at the parts where they are thinner."
This form of muscular fibre composes the whole of the voluntary muscles, all
the muscles of the ear, those of the larynx, pharynx, tongue, and upper half of
the oesophagus, the heart, and the walls of the large veins at the point where they
open into it.
The muscles of organic life (unstriped muscles) consist of flattened bands, or of
elongated, spindle-shaped fibres, flattened, of a pale color, from j^^ to 3^77 of
an inch broad, homogeneous in texture, having a finely mottled aspect, which
sometimes appears granular, the granules being occasionally arranged in a linear
series, so as to present a striated appearance. Each fibre contains a cylindrical
1 The Muscles and Fasciae 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 connection that exists between the muscles and their investing
aponeuroses, that they are considered together. Some general observations are first made on
the anatomy of the muscles and fasciae, the special description being given in connection with
the different regions.
235
236 MUSCLES AND FASCIAE.
rod-shaped nucleus, which sometimes appears as a narrow, continuous, dark streak
The fibres are united into bundles, which are connected together by areolar tissue
and elastic fibres. This form of muscular tissue occurs either scattered" in the
areolar tissue, or exists in the form of a muscular membrane, the bundles being
arranged parallel, or forming a close interlacement, crossing each other at various
angles. The muscular fibre of organic life is found in the alimentary canal, form-
ing the muscular coat of the digestive tube from the middle of the oesophagus to
the internal sphincter of the anus ; in the posterior wall of the trachea, and in the
bronchi; in the ducts of the submaxillary glands; in the gall-bladder and common
bile duct ; in the calyces and pelvis of the kidney ; in the ureters and bladder ;
and, scantily, in the urethra. In the female it is met with in the vagina, the
uterus, Fallopian tubes, and broad ligaments ; in the male, in the scrotum, the epi-
didymis, the vas deferens, vesiculoe seminales, the prostate ; and in the cavernous
bodies, in both sexes. It is found also in the coats of all arteries, in most veins,
and lymphatic vessels ; in the iris and ciliary muscle, and in the skin.
Bloodvessels are distributed in considerable abundance to the muscular tissue.
In the voluntary muscles the capillaries, which are of extremely minute size,
form narrow, oblong meshes, which run in the direction of the fibres.
The lymphatic vessels in muscles are few in number, and appear to exist only
in the largest muscles. The nerves of voluntary muscles are of large size. The
larger branches pass between the fasciculi, and, subdividing, unite to form primary
plexuses ; from these, finer bundles, or, single nerve tubes, pass between the mus-
cular fibres, and, forming loops, return to the plexus.
Each muscle is invested externally by a thin cellular layer, forming what is
called its sheath, which not only covers its outer surface, but penetrates into its
interior in the intervals between the fasciculi, surrounding these, and serving as
a bond of connection between them.
The muscles are connected with the bones, cartilages, ligaments and skin, either
directly or through the intervention of fibrous structures, called tendons or apo-
neuroses. Where a muscle is attached to bone or cartilage, the fibres terminate
in blunt extremities upon the periosteum or perichondrium, and do not come into
direct relation with the osseous or cartilaginous tissue. Where muscles are con-
nected with the skin, they either lie as a flattened layer beneath it, or are con-
nected with its areolar tissue by larger or smaller bundles of fibres, as in the
muscles of the face.
The muscles vary considerably in their form. In the limbs, they are of con-
siderable 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 inclose ; hence the reason of the terms, long, broad,
short, etc., used in the description of a muscle.
There is considerable variation in the arrangement of the fibres of certain
muscles, to the tendons to which they are attached. In some, the fibres are
arranged longitudinally, and terminate at either end in a narrow tendon. If the
fibres converge, like the plumes of a pen, to one side of a tendon, which runs the
entire length of a muscle, it is said, to be penniform, as the Peronei ; or, if they
converge to both sides of a tendon, they are called bipenniform, as the Rectus
femoris ; if they converge from a broad surface to a narrow tendinous point, they
are then said to be radiated, as the Temporal and Glutei muscles.
Their size presents considerable variation ; the Gastrocnemius forms the chief
bulk of the back of the leg, and the fibres of the Sartorius are nearly two feet in
length, whilst the Stapedius, a small muscle of the internal ear, weighs about a
grain, and its fibres are not mpre than two lines in length. Tn each case, how-
ever, they are admirably adapted to execute the various movements they are
required to perform.
The names applied to the various muscles have been derived : 1, from their situa-
tion, as the Tibialis, Radialis, Ulnaris, Peroneus ; 2, from their direction, as the
GENERAL ANATOMY. 23T
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 from having two
heads, the Triceps from having three heads ; 6, 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 upon which the
force of the muscle is directed : this holds true, however, for 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 ; in the greater number,
the muscle 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 at once to explain the
causes of displacement in the various forms of fracture, or the causes which produce
distortion in various forms of 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 bloodvessels, and the surface-
markings they produce, should be especially remembered, as they form most useful
guides to the surgeon in the application of a ligature to these vessels.
Tendons are white, glistening, fibrous cords, varying in length and thickness,
sometimes round, sometimes flattened, of considerable strength, and only slightl v
elastic. They consist almost entirely of white fibrous tissue, the fibrils of which
have an undulating course parallel with each other, and firmly united together.
They are very sparingly supplied with bloodvessels, the smaller tendons pre-
senting in their interior not a trace of them. Nerves also are not present in the
smaller tendons ; but the larger ones, as the tendo A chillis, receive nerves which
accompany the nutrient vessels. The tendons consist principally of a substance
which yields gelatine.
Aponeuroses are fibrous membranes, of a pearly- white color, iridescent, glisten-
ing, and similar in structure to the tendons. They are destitute of nerves, and
the thicker ones are only sparingly supplied with bloodvessels.
The tendons and aponeuroses are connected, on the one hand, with the muscles ;
and, on the other hand, with the movable structures, as the bones, cartilages,
ligaments, fibrous membranes (the sclerotic, for instance), and the synovial mem-
branes, the subcrureus and subanconeus for example. Where the muscular
fibres are continuous 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 fibre joins the tendon
or aponeurosis at an oblique angle, the former terminates, 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 semi-penniform muscles, and in those muscles the tendons of which
commence in a membranous form, as the Gastrocnemius and Soleus.
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 fasciae have been subdivided, from the
structure which they present, into two groups, fibro-areolar or superficial fasciae,
and aponeurotic or deep fasciae.
The fibro-areolar fascia is found immediately beneath the integument over
almost the entire surface of the body, and is generally known as the superficial
fascia. 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
238 MUSCLES AND FASCIJE.
very liable to serous infiltration. 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 into several laminae, but in the palm of the hand it is of extreme
thinness, and intimately adherent to the integument. The superficial fascia is
capable of separation into two or more layers, between which are found the
superficial vessels and nerves, and superficial lymphatic glands ; as the superficial
epigastric vessels in the abdominal region, the radial and ulnar veins in the fore-
arm, the saphenous veins in the leg and thigh, and, in certain situations, cutaneous
muscles, as the Platysma myoides in the neck, Orbicularis palpebrarum around
the eyelids. It is most distinct at the lower part of the abdomen* the scrotum,
perineum, and in the 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, and almost entirely wanting in the palms of the
hands and soles of the feet, where the integument is adherent to the subjacent
aponeurosis. The superficial fascia connects the skin to the subjacent parts, serves
as a soft nidus for the passage of vessels and nerves to the integument, and retains
the warmth of the body, from the adipose tissue contained in its areolae being a
bad conductor of caloric.
The aponeurotic or deep fascia is a dense, inelastic and 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 reticular manner. It is
usually exposed on the removal of the superficial fascia, forming a strong invest-
ment, 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. Aponeurotic fasciae are divided into two classes, aponeuroses of
insertion, and aponeuroses of investment.
The aponeuroses of insertion serve for the insertion of muscles. Some of these
are formed by the expansion of a tendon into an aponeurosis, as, for instance, the
tendon of the Sartorius ; others do not originate in tendons, as the aponeuroses
of the abdominal muscles.
The aponeuroses of investment form a sheath for the entire limb, as well as for
each individual muscle. Many aponeuroses, however, serve both for investment
and insertion. Thus, the aponeurosis given off from the tendon of the Biceps
brachialis near its insertion is continuous with, and partly forms, the investing
fascia of the forearm, and gives origin to the muscles in this region. 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 vaginae femoris and Gluteus
maximus in the thigh, by the Biceps in the leg, 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, 1. Those of the head, face, and neck. 2. Those of the trunk.
3. Those of the upper extremity. 4. Those of the lower extremity.
MUSCLES AND FASCIAE OF THE HEAD AND FACE.
The Muscles of the Head and Face consist of ten groups, arranged according
to the region in which they are situated.
1. Epicranial Eegion. 6. Superior maxillary Begion.
2. Auricular Begion. 7. Inferior maxillary Begion.
8. Palpebral Begion. 8. Intermaxillary Begion.
4. Orbital Begion. 9. Temporo-maxillary Begion.
5. Nasal Begion. 10. Pterygo-maxillary Begion.
OCCIPITO-FRONTALIS.
239
The muscles contained in each of these
1. Epicranial Region.
Occipito-frontalis.
2. Auricular Region.
Attolens aurem.
Attrahens aurem.
Retrahens aurem.
3. Palpebral Region.
Orbicularis palpebrarum.
Corrugator supercilii.
Tensor tarsi.
Levator palpebrae.
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 alaaque nasi.
Dilator naris posterior.
groups are the following: —
Dilator naris anterior.
Compressor naris.
Compressor narium minor.
Depressor alae nasi.
6. Superior Maxillary Region.
Levator labii superioris.
Levator anguli oris.
Zygomaticus major.
Zygomaticus minor.
7. Inferior Maxillary Region.
Levator labii inferioris.
Depressor labii inferioris.
Depressor anguli oris.
8. Intermaxillary Region.
Buccinator.
Risorius.
Orbicularis oris.
' 9. Temporo-maxillary Region.
Masseter.
Temporal.
10. Ptery go-maxillary Region.
Pterygoideus externus.
Pterygoideus internus.
1. Epicranial Region — Occipito-Frontalis.
Dissection (fig. 147). The head being shaved, and a block placed beneath the back of the neck,
make a vertical incision through the skin from before backwards, 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
Fig. 147. — Dissection of the Head, Face, and Neck.
-/ Dissection of scalp
2.3.qf AURICULAR REC1CW
4-.5.G.cf FACE
%.8.<f KECK
posterior extremity of the preceding. Raise the skin in front from the subjacent muscle from
below upwards; this must be done with extreme care, on account of their intimate union. The
tendon of the muscle is best avoided by removing the integument from the outer surface of the
vessels and nerves which lie between the two.
240
MUSCLES AND FASCIAE.
The superficial fascia in the epicranial region is a firm, dense layer, intimately
adherent to the integument, and to the Occipito-frontalis and its tendinous aponeu-
rosis ; it is continuous, behind, with the superficial fascia at the back part of the
neck; and, laterally, is continued over the temporal aponeurosis: it contains
Fig. 148. — Muscles of the Head. Face, and Neck.
CORRUCATOR SUPIRCIUI
O'LATO* WAR'S ANTr.
t. LATCH NAOIS POSTEH.
CCKPM55PH IIARHIM MINOR
* ALA
LEVATOR MENTI
between its layers the small muscles of the auricle, and the superficial temporal
vessels and nerves.
The Occipito-frontalis (fig. 148) is a broad musculo-fibrous layer, which covers
the whole of one side of the vertex of the skull, from the occiput to the eyebrow.
It consists of two muscular slips, separated by an intervening tendinous aponeu-
rosis. The occipital portion, thin, quadrilateral in form, and about an inch and a
AURICULAR REGION. 241
half in length, arises from the outer two-thirds of the superior curved line of the
occipital bone, and from the mastoid portion of the temporal. Its fibres of origin
are tendinous, but they soon become muscular, and ascend in a parallel direction
to terminate in the tendinous aponeurosis. The frontal portion is thin, of a quad-
rilateral form, and intimately adherent to the skin. 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. Its middle fibres become blended
with the Corrugator supercilii and Orbicularis ; and the outer fibres are also
blended with the latter muscle over the external angular process. From this
attachment, the fibres are directed upwards and join the aponeurosis below the
coronal suture. The inner margins of the two frontal portions of the muscle are
joined together for some distance above the root of the nose ; but between the
occipital portions there is a considerable, but variable, interval.
The aponeurosis covers the upper part of the vertex of the skull, being continu-
ous across the middle line with the aponeurosis of the opposite muscle. Behind,
it is attached, in the interval between the occipital regions, to the occipital protu-
berance and superior curved lines above the attachment of the Trapezius ; in fronts
it forms a short angular prolongation between the frontal portions ; and on each
side, it has connected with it the Attollens aurem and Attrahens aurem muscles.
In this situation it loses its aponeurotic character, and is continued over the temporal
fascia to the zygoma by a layer of laminated areolar tissue. -This aponeurosis is
closely connected to the integument by a dense fibro-cellular tissue, which contains
much granular fat, and in which ramify the numerous vessels and nerves of the
integument ; it is loosely connected with the pericranium by a quantity of loose
cellular tissue, which allows of a considerable degree of movement of the integu-
ment.
Nerves. The frontal portion of the Occipito-frontalis is supplied by the supra-
orbital and facial nerves ; the occipital portion by the posterior auricular branch
of the facial, and, sometimes, by the small occipital.
Actions. The frontal portion of the muscle raises the eyebrows and the skin
over the root of the nose ; at the same time throwing the integument of the fore-
head into transverse wrinkles, a predominant expression in the emotions of delight.
By bringing alternately into action the occipital and frontal portions, the entire
scalp may be moved from before backwards.
2. Auricular Region (fig. 148).
Attollens Aurem. Attrahens Aurem.
Retrahens Aurem.
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 man-
ner. To expose the Attollens aurem, draw the pinna or broad part of the ear downwards,
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 the tendon, in a direction from below upwards,
and then reflecting it on each side, the muscle is exposed. To bring into view the Attrahens
aurem, draw the helix backwards 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 Eetrahens aurem, draw
the pinna forwards, 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.
The Attollens Aurem, the largest of the three, is thin, and fan-shaped; it
arises from the aponeurosis of the Occipito-frontalis, and its fibres converge to
be inserted by a thin, flattened tendon into the upper part of the cranial surface
of the pinna.
16
242 MUSCLES AND FASCIA.
Relations. Externally, with the integument; internally, with the Temporal
aponeurosis.
The Attrahem Aurem, the smallest of the three, is thin, fan-shaped, and its
fibres pale and indistinct. It arises from the lateral edge of the aponeurosis of
the Occipito-frontalis ; its fibres converge to be inserted into a projection on the
front of the helix.
Relations. Externally, with the skin ; internally, with the temporal fascia, which
separates it from the temporal artery and vein.
The Retrahens Aurem 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. Externally, with the integument ; internally, with the mastoid portion
of the temporal bone.
Nerves. The Attollens aurem is supplied by the small occipital ; the Attrahens
aurem, by the facial and auriculotemporal branch of the inferior maxillary ; and
the Eetrahens aurem, by the posterior auricular branch of the facial.
Actions. In man, these muscles possess very little action ; the Attollens aurem
slightly raises the ear, the Attrahens aurem draws it forwards and upwards, and
the Eetrahens aurem draws it backwards.
3. Palpebral Eegion (fig. 148).
Orbicularis Palpebrarum. Levator Palpebral
Corrugator Supercilii. . Tensor Tarsi.
Dissection (fig. 147). In order to expose the muscles of the face, continue the longitudinal
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 onwards to the upper lip ; another incision should be carried
along the margin of the lip to the angle of the mouth, and transversely across the face to the
angle of the jaw. The integument should also be divided by an incision made in front of the
external ear, from the angle of the jaw, upwards, to the transverse incision made in exposing
the Occipito-frontalis. These incisions include a square-shaped flap which should be carefully
removed in the direction marked in the figure, as the muscles at some points are intimately adhe-
rent to the integument.
The Orbicularis Palpebrarum is a sphincter muscle which surrounds the cir-
cumference of the orbit and eyelids. It arises from the internal angular process of
the frontal bone, from the nasal process of the superior maxillary in front of the
lachrymal groove, and from the anterior surface and borders of a short tendon, the
tendo palpebrarum, placed at the inner angle of the orbit. From this origin, the
fibres are directed outwards, forming a broad, thin, and flat layer, which covers
the eyelids, surrounds the circumference of the orbit, and spreads out over the
temple, and downwards on the cheek, becoming blended with the Occipito-fronta-
lis and Corrugator supercilii. The palpebral portion (ciliaris) 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 united on the outer side of the eyelids
at an acute angle by a cellular raphe, some being inserted into the external tarsal
ligament and malar bone. The orbicular portion (orbicularis latus) is thicker, and
of a reddish color, its fibres, well developed, forming a complete ellipse.
The tendo palpebrarum (tendo oculi) 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 cartilage. As the tendon crosses the lachrymal sac, a strong aponeurotic
lamina is given off from its 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 palpebrarum.
Relations. By its superficial surface, with the integument. By its deep surface,
above, with the Occipito-frontalis and Corrugator supercilii, with which it is
intimately blended, and with the supra-orbital vessels and nerve ; below, it covers
ORBITAL REGION. 243
the lachrymal sac, and the origin of the Levator labii superioris, and the Levator
labii superioris alasque nasi 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 a fibrous membrane and the tarsal car-
tilages.
The Corrugator Supercilii 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 extremity of the superciliary ridge ;
its fibres pass upwards and outwards, to be inserted into the under surface of the
orbicularis, opposite the middle of the orbital areh.
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 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 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 cartilages near the puncta lacrymalia.
Its fibres appear to be continuous with those of the palpebral portion of the Orbi-
cularis; it is occasionally very indistinct.
Nerves. The Orbicularis palpebrarum and Corrugator supercilii are supplied by
the facial and supra-orbital nerves ; the Tensor tarsi by the facial.
Actions. The Orbicularis palpebrarum is the sphincter muscle of the eyelids.
The palpebral portion acts involuntarily in closing the lids, and independently of
the orbicular portion, which is subject to the will. When the entire muscle is
brought into action, the integument of the forehead, temple, and cheek is drawn
inwards towards the inner angle of the eye, and the eyelids are firmly closed.
The Levator palpebroa is the direct antagonist of this muscle ; it raises the upper
eyelid, and exposes the globe. The Corrugator supercilii draws the eyebrow
downwards and inwards, producing the vertical wrinkles of the forehead. This
muscle may be regarded as the principal agent in the expression of grief. The
Tensor tarsi draws the eyelids and the extremities of the fachrymal canal inwards,
and compresses them against the surface of the globe of the eye ; thus placing
them in the most favorable situation for receiving the tears. It serves, also, to
compress the lachrymal sac.
4. Orbital Region (fig. 149).
Levator Palpebrse. Rectus Internus.
Rectus Superior. Rectus Externus.
Rectus Inferior. Obliquus Superior.
Obliquus Inferior.
Dissection. To open the cavity of the orbit, the sknll-cap and brain should be first removed ;
then saw through the frontal bone at the inner extremity of the supra-orbital ridge, and externally
at its junction with the malar. The thin roof of the orbit should then be comminuted by a few
slight blows with the hammer, and the superciliary portion of the frontal bone driven forwards
by a smart stroke ; but it must not be removed. The several fragments may then be detached,
when 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. To facili-
tate their dissection, the globe of the eye should be distended ; this may be effected by puncturing
the optic nerve near the eyeball, with a curved needle, and pushing it onwards into the globe.
Through this aperture the point of a blow-pipe should be inserted, and a little air forced into
the cavity of the eyeball ; then apply a ligature round the nerve, so as to prevent the air escaping.
The globe should now be drawn forwards, when the muscles will be put upon the stretch.
The Levator Palpebrse Stiperioris is thin, flat, and triangular in shape. It
arises from the under siirface of the lesser wing of the sphenoid, immediately in
244
MUSCLES AND FASCIAE.
front of the optic foramen ; and is inserted, by a broad aponeurosis, into the upper
border of the superior tarsal cartilage. At its origin, it is narrow and tendinous;
but soon becomes broad and fleshy, and finally terminates in a broad aponeurosis.
Relations. By its upper surface, with the frontal nerve and artery, the peri-
osteum of the orbit ; and, in front, with the inner surface of the broad tarsal
ligament. By its under surface, with the Superior rectus ; and, in the lid, with
the conjunctiva. A small branch of the third nerve enters its under surface.
Fig. 149.— Muscles of the Right Orbit.
The Rectus Superior, the thinnest and narrowest of the four Eecti, arises from
the upper margin of the optic foramen, beneath the Levator palpebrae, and Supe-
rior oblique, 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 palpebrce. By its under
surface, with the optic nerve, the ophthalmic artery, and nasal nerve; and, in
front, with the tendon of the Superior oblique, and the globe of the eye.
The Inferior and Internal Recti arise by a common tendon, the ligament of
Zinn, which is attached round the circumference of the optic foramen, except at
its upper and outer part. The External
rectus 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 pointed process of bone
on the lower margin of the sphenoidal fissure.
Each muscle passes forward in the position
implied by its name, to be inserted, by a ten-
dinous expansion, 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 pass
the third, nasal branch of the fifth, and sixth
nerves, and the ophthalmic vein. Although
nearly all these muscles present a common origin, and are inserted in a similar
manner in the sclerotic coat, there are certain differences to be observed in them,
as regards their length and breadth. The Internal rectus is the broadest : the
External, the longest ; and the Superior, the thinnest and narrowest.
Fig. 150.— The relative Position and
Attachment of the Muscles of the
Left Eyeball.
IZtrtlis AujatTLoT
FalftbraSHptTiar
Olliqtuis Superior
Itcctus Inferior
ORBITAL REGION. 245
The Superior Oblique is a fusiform muscle, placed at the upper and inner side
of the orbit, internal to the Levator palpebrae. It arises about a line above the
inner margin of the optic foramen, and, passing forwards to the inner angle of the
orbit, terminates in a rounded tendon, which passes through a fibro-cartilagmous
ring, attached by fibrous tissue to a depression beneath the internal angular pro-
cess of the frontal bone, the contiguous surfaces of the tendon and ring being lined
by a delicate synovial membrane, and inclosed in a thin fibrous investment. The
tendon is reflected backwards and outwards beneath the Superior rectus to the
outer part of the globe of the eye, and is inserted into the sclerotic coat, midway
between the cornea and entrance of the optic nerve, 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 fourth nerve. By its under surface, with the nasal nerve, and the
upper border of the Internal rectus.
The Inferior Oblique is a thin, narrow muscle, placed near the anterior margin
of the orbit. It arises from a depression in the orbital plate of the superior
maxillary bone, external to the lachrymal groove. Passing outwards and back-
wards beneath the Inferior rectus, and between the eyeball and the External rectus,
it is inserted into the outer part of the sclerotic coat between the Superior and
External rectus, and near the tendon of insertion of the Superior oblique.
Relations. By its upper surface, with the globe of the eye, and with the Inferior
rectus. By its under surface, with the periosteum covering the floor of the orbit,
and with the External rectus. Its borders look forwards and backwards ; the
posterior one receives a branch of the third nerve.
Nerves. The Levator palpebrae, Inferior oblique, and all the Recti excepting the
External, are supplied by the third nerve ; the Superior oblique, by the fourth ;
the External rectus, by the sixth.
Actions. The Levator palpebrae raises the upper eyelid, and is the direct anta-
gonist 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
upwards, downwards, inwards, or outwards, as expressed by their names. If any
two Recti act together, they carry the globe of the eye in the diagonal of these
directions, viz., upwards and inwards, upwards and outwards, downwards and in-
wards, or downwards and outwards. The movement of circumduction, as in
turning the eyes round a room, is performed by the alternate action of the four
Recti. By some anatomists, these muscles have been considered the chief agents
in adjusting the sight at different distances, by compressing the globe, and so
lengthening its antero-posterior diameter. The Oblique muscles rotate the eye-
ball 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.1
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 one or the other muscle for the cure of stra-
bismus. In convergent strabismus, which is the most common form of the disease, the eye is
turned inwards, requiring the division of the Internal rectus. In the divergent form, which is
more rare, the eye is turned outwards, the External rectus being especially implicated. The de-
formity produced in either case is considerable, and is easily remedied by division of one or the
other muscle. This operation is readily effected by having the lids well separated by retractors
held by an assistant ; the eyeball being drawn outwards, the conjunctiva should be raised by a
pair of forceps, and divided immediately beneath the lower border of the tendon of the Internal
rectus, 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 upwards between the muscle and
the globe, and the tendon of the muscle and conjunctiva covering it divided by a pair of blank
pointed scissors. Or the tendon may be divided by a sub-conjunctival incision, one blade of the
1 " On the Oblique Muscles of the Eye in Man and Yertebrate Animals," by John Strutters,.
M. D. u Anatomical and Physiological Observations."
9*6 MUSCLES AND FASCIA.
scissors being passed upwards between the tendon and the conjunctiva, and the other between
the tendon and 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 these tendons, and on the opposite side the operation may be performed.
5. Nasal Region (fig. 148).
Pyramidalis Nasi. ,
Levator Labii Superioris Alaeque Nasi.
Dilator Naris Posterior.
Dilator Naris Anterior.
Compressor Naris.
Compressor Narium Minor.
Depressor Alae Nasi.
The Pyramidalis Nasi is a small pyramidal slip, prolonged downwards from
the Occipito-frontalis upon the side of the nose, where it becomes tendinous, and
blends with the Compressor naris. As the two muscles descend, they diverge,
leaving an angular interval between them.
Relations. By its upper surface, with the skin. By its under surface, with the
frontal and nasal bones.
The Levator Labii Superioris Alseque 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 pro-
cess of the superior maxillary bone, and passing obliquely downwards and out-
wards, divides into two slips, one of which is inserted into the cartilage of the ala
of the nose, the other is prolonged into the upper lip, becoming blended with
the Orbicularis and Levator labii proprius.
Relations. In front, with the integument ; and with a small part of the Orbi-
cularis palpebrarum above.
Lying upon the superior maxillary bone, beneath this muscle, is a longitudinal
muscular fasciculus about an inch in length. It is attached by one end near the
origin of the Compressor naris, and by the other to the nasal process about an
inch above it; it was described by Albinus as the "Musculus anomalus," and by
Santorini, as the " Rhomboideus."
The Dilator naris posterior is a small muscle, which is placed partly beneath
the proper 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 carti-
lage of the ala of the nose to the integument near its margin. This muscle is
situated in front of the preceding.
The Compressor Naris 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 upwards and inwards, 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.
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 Alse Nasi is a short, radiated muscle, arising from the incisive
fossa of the superior maxilla ; its fibres ascend to be inserted into 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 the muscles of this group are supplied by the facial nerve.
Actions. The Pyramidalis nasi draws down the inner angle of the eyebrow ; by
some anatomists it is also considered as an elevator of the ala, and, consequently,
a dilator of the nose. The Levator labii superioris alaeque nasi draws upwards
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 is the principal agent in the expression
of contempt. The two Dilatores nasi enlarge the aperture of the. nose, and the
Compressor naris appears to act as a dilator of the nose rather than as a constrictor.
The Depressor alee nasi is a direct antagonist of the preceding muscles, drawing
the ala of the nose downwards, and thereby constricting the aperture of the nares.
6. Superior Maxillary Kegion (fig. 148).
Levator Labii Superioris. Zygomaticus major.
Levator Anguli Oris. Zygomaticus minor.
The Levator Labii Superioris 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, some to the
malar bone ; its fibres converge to be inserted into the muscular substance of the
upper lip.
Relations. By its superficial surface, with the lower segment of the Orbicu-
laris palpebrarum; below, it is subcutaneous. By its deep surface, it conceals
the origin of the Compressor naris and Levator anguli oris muscles, and the infra-
orbital vessels and nerves, as they escape from the infra-orbital foramen.
The Levator Anguli Oris arises from the canine fossa, immediately below the
infra-orbital foramen ; its fibres incline downwards and a little outwards, to be
inserted into the angle of the mouth, and intermingle with those of the Zygo-
matici, the. Depressor anguli oris, and the Orbicularis.
Relations. By its superficial surface, with the Levator labii superioris and the
infra-orbital vessels and nerves. By its deep surface, with the superior maxilla,
the Buccinator, and the mucous membrane.
The Zygomaticus major is a slender fasciculus, which arises from the malar
bone, in front of the zygomatic suture, and, descending obliquely downwards and
inwards, is inserted into the angle of the mouth, where it blends with the fibres
of the Orbicularis and Depressor anguli oris.
Relations. By its superficial surface, with the subcutaneous adipose tissue.
By its deep surface, with the malar bone, the Masseter and Buccinator muscles.
The Zygomaticus minor arises from the malar bone, immediately behind the
maxillary suture, and, passing downwards and inwards, is continuous with 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 Levator anguli oris.
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 outwards. The Levator anguli oris raises the
angle of the mouth and draws it inwards ; whilst the Zygomatici raise the upper
lip and draw it somewhat outwards, as in laughing.
7. Inferior Maxillary Kegion (fig. 148).
Levator Labii Inferioris or Levator menti.
Depressor Labii Inferioris or Quadratus menti.
Depressor Anguli Oris or Triangularis menti.
Dissection. The Muscles in this region maybe 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 carefully
removed in the direction shown in fig. 147.
The Levator Labii Inferioris or Levator menti is to be dissected by everting the
lower lip and raising the mucous membrane. It is a small conical fasciculus.
248 MUSCLES AND FASCIJ3.
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.
Relations. 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 Quadratics menti is a small quadrilateral
muscle, situated at the outer side of the preceding. It arises from the external
oblique line of the lower jaw, between the symphysis and mental foramen, and
passes obliquely upwards and inwards, to be inserted into the integument of the
lower lip, its fibres blending with the Orbicularis, 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 is triangular in shape, arising, by its broad base,
from the external oblique line of the lower jaw ; its fibres pass upwards, 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 and Eisorius at its
insertion.
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 for-
wards ; at the same time it wrinkles the integument of the chin. The Depressor
labii inferioris draws the lower lip directly downwards and a little outwards. The
Depressor anguli oris depresses the angle of the mouth, being the great antagonist
to the Levator anguli oris and Zygomaticus major : acting with these muscles, it
will draw the angle of the mouth directly backwards.
8. Intermaxillary Eegion. n
Orbicularis Oris. Buccinator. Eisorius.
Dissection. The dissection of these muscles may be consideraoly 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 is a sphincter muscle, elliptic in form, composed of con-
centric fibres, which surround the orifice of the mouth. It consists of two thick
semicircular planes of muscular fibre, which surround the oral aperture, and
interlace on either side with those of the Buccinator and other muscles inserted
into this part. On the free margin of the lips the muscular fibres are continued
uninterruptedly from one lip to the other, around the corner of the mouth, forming
a roundish fasciculus of fine pale fibres closely approximated. To the outer part
of each segment some special fibres are added, by which the lips are connected
directly with the maxillary bones and septum of the nose. The additional fibres
for the upper segment consist of four bands, two of which, the Accessorii orbicularis
superioris, arise from the alveolar border of the superior maxilla, opposite the
incisor teeth, and, arching outwards 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 Naso-labialis, connect the upper lip to the septum of the
nose : as they descend from the septum, an interval is left between them, which
corresponds to that left by the divergence of the accessory portions of the Orbi-
cularis above described. It is this interval which forms the depression seen on
the surface of the skin beneath the septum of the nose.
TEMPORO-MAXILLARY REGIO.N. 249
The additional fibres for the lower segment, Accessorii orbicularis inferioris,
arise from the inferior maxilla, externally to the Levator labii inferioris ; arching
outwards to the angles of the mouth, they join the Buccinator and the other
muscles attached to this spot.
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
numerous muscles which converge to the mouth from various parts of the face.
Its inner circumference is free, and covered by mucous membrane.
The Buccinator is a broad, thin muscle, quadrilateral in form, occupying 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, corresponding to the last
three molar teeth ; and, behind, from the anterior border of the pterygo-maxil-
lary ligament. The fibres converge towards the angle of the mouth, where the
central ones intersect each other, those from below being continuous with the
upper segment of the Orbicularis oris, and those from above, with the inferior
segment ; but the highest and lowest fibres continue forward uninterruptedly into
the corresponding segment of the lip, without decussation.
Relations. By its superficial surface, behind, with a large mass of fat, which
separates it from the ramus of the lower jaw, the Masseter, and a small portion of
the Temporal muscle; anteriorly, with the Zygomatici, Risorius, Levator anguli
oris, Depressor anguli oris, and Stenon's duct, which pierces it opposite the second
molar tooth of the upper jaw ; the facial artery and vein cross it from below
upwards, and 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 ligament separates the Buccinator muscle from the Supe-
rior constrictor of the pharynx. It is a tendinous band, 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 corre-
sponds 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 Risoruis of Santorini consists of a narrow bundle of fibres, which arises in
the fascia over the Masseter muscle, and, passing horizontally forwards, is inserted
into the angle of the mouth, joining with the fibres of the Depressor anguli oris.
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 Orbicularis oris is supplied by the facial, the Buccinator by the
facial and buccal branch of the inferior maxillary nerve.
Actions. The Orbicularis oris is the direct antagonist of all those muscles which
converge to the lips from the various parts of the face, its action producing the
direct closure of the lips ; and its forcible action throwing the integument into
wrinkles, on account of the firm connection between the latter and the surface of
the muscle. The Buccinators contract and compress the cheeks, so that, during
the process of mastication, the food is kept under the immediate pressure of the
teeth.
9. Temporo-maxillary Region" (fig. 151).
Masseter. Temporal.
The Masseter has been already exposed by the removal of the integument from
the side of the face (fig. 148).
The Masseter is a short thick muscle, somewhat quadrilateral in form, consisting
of two portions, superficial and deep. The superficial portion, the largest, 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
250
MUSCLES AND FASCIAE.
fibres pass downwards and backwards, to be inserted into the angle and lower
half of the ramus of the jaw. The deep portion is much smaller, and more mus-
cular in texture, and arises from the posterior third of the lower border and whole
of the inner surface of the zygomatic arch ; its fibres pass downwards and for-
wards 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 integument; above, with the
Orbicularis palpebrarum and Zygomatici ; and has passing across it, transversely,
Stenon's duct, the branches of the facial nerve, and the transverse facial vessels.
By its deep surface, with the ramus of the jaw, and the Buccinator, from which it
is separated by a mass of fat. Its posterior margin is overlapped by the parotid
gland. Its anterior margin projects over the Buccinator muscle.
The temporal fascia is seen, at this stage of the dissection, covering in the Tem-
poral muscle. It is a strong aponeurotic investment, affording attachment, by its.
inner surface, to the superficial fibres of this muscle. Above, it is a single layer,
attached to the entire extent of the temporal 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
branch of the superior maxillary nerve, are contained between these two layers.
It is covered, on its outer surface, by the aponeurosis of the Occipito-frontalis, the
Orbicularis palpebrarum, and Attollens aurem and Attrahens aurem muscles;
the temporal vessels and nerves cross it from below upwards.
Fig. 151. — The Temporal Muscle, the Zygoma and Masseter having been removed.
Dissection. In order to expose the Temporal muscle, this fascia should be removed ; this may
be effected by separating it at its attachment along the upper border of the zygoma, and dissect-
ing it upwards 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 downwards with the Masseter. which should be detached from its insertion into the ramus
;md angle of the jaw. The whole extent of the Temporal muscle is then exposed.
PTERYGO-MAXILLARY REGION.
25i
The Temporal is a broad radiating muscle situated at the side of the head, and
occupy iug the entire extent of the temporal fossa. It arises from the whole of
the temporal fossa, which 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 aponeurosis, 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 forwards as the last molar tooth.
Relations. By its superficial surface, with the integument, the temporal fascia,
aponeurosis of the Occipito-frontalis, the Attollens aurem and Attrahens aurem
muscles, the temporal vessels and nerves, the zygoma and Masseter. By its deep
surface, with the temporal fossa, the External pterygoid and part of the Bucci-
nator muscles, the internal maxillary artery, its deep temporal branches, and
the temporal nerves.
Nerves. Both muscles are supplied by the inferior maxillary nerve.
10. Pterygo-maxillary Region.
Internal Pterygoid. External Pterygoid.
Dissection. The Temporal muscle having been examined, the muscles in the pterygo-maxil-
lary region may be exposed by sawing through the base of the coronoid process, and drawing it
upwards, 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 commencement of its lower third, just above the dental foramen ;
remove the fragment, and the Pterygoid muscles will be exposed.
Fig. 152. — The Pterygoid Muscles ; the Zygomatic Arch and a portion of the
Ramus of the Jaw having been removed.
The Internal Pterygoid is a thick quadrilateral muscle, and resembles the
Masseter in form, structure, and in the direction of its fibres. It arises from the
pterygoid fossa, its fibres being attached to the inner surface of the external
pterygoid plate, and to the grooved surface of the tuberosity of the palate bone ;
252 MUSCLES AND FASCIA.
its fibres pass downwards, outwards, and backwards, to be inserted, by strong
tendinous laminae, 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, the internal lateral
ligament, the internal maxillary artery, and the dental vessels and nerves. By its
internal surface, with the Tensor palati, being separated from the Superior con-
strictor of the pharynx by a cellular interval.
The External Pterygoid is a short thick muscle, somewhat conical in form, and
extends almost horizontally between the zygomatic fossa and the condyle of the
jaw. It arises from the pterygoid ridge on the great wing of the sphenoid, and
the portion of bone included between it and the base of the pterygoid process ;
from the outer surface of the external pterygoid plate ; and from the tuberosity of
the palate and superior maxillary bones. Its fibres pass horizontally backwards
and outwards, 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 fibro-
cartilage. This muscle, at its origin, appears to consist of two portions separated
by a slight interval ; hence the terms upper and lower head sometimes used in the
description of the muscle.
Relations. By its external surf ace, with the ramus of the lower jaw, the internal
maxillary artery which crosses it, the tendon of the Temporal muscle, and the
Masseter. By its internal surface, it rests against the upper part of the Internal
pterygoid, 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.
Nerves. These muscles are supplied'by the inferior maxillary nerve.
Actions. The Temporal, Masseter, and Internal pterygoid raise the lower jaw
against the upper with great force. The two latter muscles, from the obliquity
in the direction of their fibres, assist the External pterygoid in drawing the
lower jaw forwards 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 forwards, 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
forwards, and the other condyle remaining fixed, the symphysis deviates to the
opposite side. The alternation of these movements on the two sides produces
trituration.
MUSCLES AND FASCIAE 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 Eegion. 5. Muscles of the Pharynx.
2. Infra-hyoid Eegion. 6. Muscles of the Soft Palate.
Depressors of the Os Hyoides
and Larvnx. 7. Muscles of the Anterior Verte-
bral Eegion.
3. Supra-hyoid Eegion.
Elevators of the Os Hyoides 8. Muscles of the Lateral Vertebral
and Larynx. Eegion.
4. Lingual Eegion. 9. Muscles of the Larynx.
Muscles of the Tongue.
SUPERFICIAL CERVICAL REGION.
253
1. Superficial Region.
Platysraa myoides.
Sternocleidomastoid .
2. Infra-hyoid Region.
Depressors of the Os Hyoides and
Larynx.
Sterno-hyoid.
Sterno-thyroid.
Thyrohyoid.
Omohyoid.
3. Supra-hyoid Region.
Elevators of the Os Hyoides and
Larynx.
Digastric.
Stylo-hyoid.
Mylo-hyoid.
Genio-hyoid.
4. Lingual Region.
Muscles of the Tongue.
Genio-hyo-glossus.
Hyo-glossus.
Lingualis.
Stylo-glossus.
Palato-glossus.
5. Muscles of the Pharynx.
Constrictor inferior.
Constrictor medius.
Constrictor superior.
Stylo-pharyngeus.
Palato-pharyngeus.
6. Muscles of the Soft Palate.
Levator palati.
Tensor palati.
Azygos uvulae.
Palato-glossus.
Palato-pharyngeus.
7. Muscles of the Anterior Vertebral
Region.
Rectus capitis anticus major.
Rectus capitis anticus minor.
Rectus lateralis.
Longus colli.
8. Muscles of the Lateral Vertebral
Region.
Scalenus anticus.
Scalenus medius.
Scalenus posticus.
9. Muscles of the Larynx.
(Included in the description of the
Larynx.)
1. 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 to that to be dissected, so as to place the parts upon the stretch, two transverse
incisions are to be made : 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. These are to be connected 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. 147,
the superficial fascia will be exposed.
The superficial cervical fascia is exposed on the removal of the integument from
the side of the neck ; it is an extremely thin aponeurotic lamina, which is hardly
demonstrable as a separate membrane. Beneath it is found the Platysma myoides
muscle, the external jugular vein, and some superficial branches of the cervical
plexus of nerves.
The Platysma Myoides (fig. 148) is a broad thin plane of muscular fibres, placed
immediately beneath the skin on each side of the neck. It arises from the clavicle
and acromion, and from the fascia covering the upper part of the Pectoral, Deltoid,
and Trapezius muscles ; its fibres proceed obliquely upwards and inwards along the
aide of the neck, to be inserted into the lower jaw beneath the external oblique
line, some fibres passing forwards to the angle of the mouth, and others becoming
lost in the cellular tissue of the face. The most anterior fibres interlace, in front
of the jaw, with the fibres of the muscle of the opposite side ; those next in order
become blended with the Depressor labii inferioris and the Depressor anguli oris ;
others are prolonged upon the side of the cheek, and interlace, near the angle of
the mouth, with the muscles in this situation, and may occasionally be traced to
the Zygomatic muscles, or to the margin of the Orbicularis palpebrarum. Beneath
254 MUSCLES AND FASCIAE.
the Platysma, the external jugular vein may be seen descending from the angle of
the jaw to the clavicle. It is essential to remember the direction of the fibres of
the Platysma, in connection with the operation of bleeding from this vessel ; for
if the point of the lancet is introduced in the direction of the muscular fibres, the
orifice made will be filled up by the contraction of the muscle, and blood will not
flow ; but if the incision is made in a direction opposite to the course of the fibres,
they will retract, and expose the orifice in the vein, and so facilitate the flow of
blood.
Relations. By its external surface, with the integument to which it is united
closely below, but more loosely above. By its internal surface, below the clavicle
which it covers, with the Pectoralis major, Deltoid, and Trapezius. In the neck,
with the external and anterior jugular veins, the deep cervical fascia, the super-
ficial cervical plexus, the Sterno-mastoid, Sterno-hyoid, Omo-hyoid, and Digastric
muscles. In front of the Sterno-mastoid, it covers the sheath of the carotid ves-
sels ; and behind it, the Scaleni muscles and the nerves of the brachial plexus.
On the face, it is in relation with the parotid gland, the facial artery and vein, and
the Masseter and Buccinator muscles.
The deep cervical fascia is exposed on the removal of the Platysma myoides.
It is a strong fibrous layer, which invests the muscles of the neck, and incloses
the vessels and nerves. It commences, as an extremely thin layer, at the back
part of the neck, where it is attached to the spinous processes of the cervical
vertebras, and to the ligamentum nuchse ; and, passing forwards to the posterior
border of the Sterno-mastoid muscle, divides into two layers, one of which passes
in front, and the other behind it. These join again at its anterior border ; and,
being continued forwards to the front of the neck, blend with the fascia of the
opposite side. The superficial layer of the deep cervical fascia, that which passes
in front of the Sterno:mastoid, if traced upwards, is found to pass across the
parotid gland and Masseter muscle, forming the parotid and masseteric fasciae,
and is attached to the lower border of the zygoma, and more anteriorly ..to the
lower border of the body of the jaw ; if the same layer is traced downwards, it is
seen to pass to the upper border of the clavicle and sternum, being pierced just
above the former bone for the external jugular vein. In the middle line of the
neck, the fascia is thin above, and connected to the hyoid bone ; but it becomes
thicker below, and divides, just below the thyroid gland, into two layers, the more
superficial of which is attached to the upper border of the sternum and inter-
clavicular ligament; the deeper and stronger layer is connected to the posterior
border of that bone, covering in the Sterno-hyoid and Sterno-thyroid muscles.
Between these two layers is a little areolar tissue and fat, and occasionally a
small lymphatic gland. The deep layer of the cervical fascia, that which lies
behind the posterior surface of the Sterno-mastoid, sends numerous prolongations,
which invest the muscles and vessels of the neck ; if traced upwards, a process of
this fascia, of extreme density, passes behind and to the inner side of the parotid
gland, and is attached to the base of the styloid process and angle of the lower
jaw, forming the stylo-maxillary ligament; if traced downwards and outwards, it
will be found to inclose the posterior belly of the Omo-hyoid muscle, binding it
down by a distinct process, which descends to be inserted into the clavicle and
cartilage of the first rib. The deep layer of the cervical fascia also assists in
forming the sheath which incloses the common carotid artery, internal jugular
vein, and pneumogastric nerve. There are fibrous septa intervening between
each of these parts, which, however, are included together in one common invest-
ment. More internally, a thin layer is continued across the trachea and thyroid
gland, beneath the Sterno-thyroid muscles ; and at the root of the neck this may
be traced, over the large vessels, to be continuous with the fibrous layer of the
pericardium.
The Sterno-cleido-mastoid (fig. 153) is a large thick muscle, which passes
obliquely across the side of the neck, being inclosed between the two layers of
the deep cervical fascia. It is thick and narrow at its central part, but is broader
SUPERFICIAL CERVICAL REGION.
255
and thinner at each extremity. It arises, by two heads, from the sternum and
clavicle. The sternal portion arises by a rounded fasciculus, tendinous in front,
fleshy behind, from the upper and anterior part of the first piece of the sternum,
and is directed upwards and backwards. The clavicular portion arises from the
inner third of the superior border of the clavicle, being composed of fleshy and
aponeurotic fibres ; it is directed almost vertically upwards. These two portions
are separated from one another, at their origin, oy 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, from the apex to its superior border, and by a thin aponeurosis into the
outer two-thirds of the superior curved line of the occipital bone. This muscle
varies much in its extent of attachment to the clavicle ; in one case it may be as
narrow as the sternal portion, in another as much as three inches in breadth.
Fig. 153. — Muscles of the Neck, and Boundaries of the Triangles.
When the clavicular origin is broad, it is occasionally subdivided into numerous
slips, separated 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 to the third part of the subclavian artery, it will be necessary, where
the muscles have an arrangement similar to that above-mentioned, to divide a
portion of one or of both, in order to facilitate the operation.
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
being, 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
256 MUSCLES AND FASCIA.
process ; behind, the anterior border of the Sterno-mastoid muscle. The boundaries
of the posterior triangle are, in front, the posterior border of the Sterno-mastoid ;
below, the upper border of the clavicle; behind, the anterior margin of the
Trapezius.
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 cesoph-
agotomy.
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 rests on the sterno-clavicular articulation, the deep layer of the cervical
fascia, the Sterno-hyoid, Sterno-thyroid, Omo-hyoid, the posterior belly of the
Digastric, Levator anguli scapulae, the Splenius and Scaleni muscles. Below, with
the lower part of the common carotid artery, internal jugular vein, pneumogastric,
descendens noni, and communicans noni nerves, and with the deep lymphatic
glands ; with the spinal accessory nerve, which pierces its upper third, the cervical
plexus, the occipital artery, and a part of the parotid gland.
• Nerves. The Platysma myoides is supplied by the facial and superficial cer*
vical nerves, the Sterno-cleido-mastoid by the spinal accessory and deep branches
of the cervical plexus.
Actions. The Platysma myoides produces a slight wrinkling of the surface of
the skin of the neck, in a vertical 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 sider being one of the chief agents in the expression of melancholy. The
Sterno-mastoid muscles, when both are brought into action, serve to depress the
head upon the neck, and the neck upon the chest. Either muscle, acting singly,
flexes the head, and combined with the Splenius draws it towards the shoulder
of the same side, and rotates it so as to carry the face towards the opposite side.
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 wryneck. One variety of this distortion is produced by spasmodic contraction
or rigidity of the Sterno-mastoid ; the head being carried down towards the shoulder of the same
side, and the face turned to the opposite side, and fixed in that position. When all other reme-
dies for the relief of this disease have failed, subcutaneous division of the mnscle is resorted to.
This is performed by introducing a long narrow bistoury beneath it, about half an inch above its
origin, and dividing it from behind forwards whilst the muscle is put well upon the stretch.
There is seldom any difficulty in dividing the sternal portion. 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.
2. Infea-hyoid Eegion (figs. 153 and 154).
Depeessors of the Os Hyoides and Laeynx.
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, if this muscle has been previously dissected ; but not otherwise.
The Sterno-hyoid is a thin, narrow, riband-like muscle, which arises from
the inner extremity of the clavicle, and the upper and posterior part of the first
piece of the sternum ; and, passing upwards and inwards, is inserted, by short
tendinous fibres, into the lower border of the body of the os hyoides. This
INFRA-HYOID REGION.
257
muscle is separated, below, from its fellow by a considerable interval ; but they
approach one another in the middle of their course, and again diverge as they
ascend. It often presents, immediately above its origin, a transverse tendinous
intersection, analogous to those in the Rectus abdominis.
Variations. This muscle sometimes arises from the inner extremity of the clavicle, and the
posterior sterno-clavicular ligament, or from the sternum and this ligament; from either bone
alone, or from all these parts ; and occasionally has a fasciculus connected with the cartilage of
the first rib.
Relations. By its superficial surface, below, with the sternum, 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
Thyro-hyoid muscles, the thyroid gland, the superior thyroid vessels, the
crico-thyroid and thyro-hyoid membranes.
Fig. 154. — Muscles of the Neck. Anterior View.
The Slerno-ihyroid is situated beneath the preceding muscle, but is shorter
and wider. It arises from the posterior surface of the first bone of the
sternum, below the origin of the Sterno-hyoid, and occasionally from the edge of
the cartilage of the first rib, 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 frequently traversed by a trans-
verse or oblique tendinous intersection, analogous to those in the Rectus
abdominis.
Variations. This muscle is sometimes continuous with the Thyro-hyoid and Inferior con-
strictor of the pharynx ; and a lateral prolongation from it sometimes passes as- far as the o.s
hyoides.
17
258 MUSCLES AND FASCIAE.
Relations. By its anterior surface, with the Sternohyoid, Omohyoid, and
Sterno-mastoid. By its posterior surface, from below upwards, 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. The middle
thyroid vein lies along its inner border; an important relation to be remembered in
the operation of tracheotomy.
The TJiyro-hyoid is a small quadrilateral muscle, appearing like a continuation
of the Sterno-thyroid. It arises from the oblique line on the side of the thyroid
cartilage, and passes vertically upwards to be inserted into the lower border of
the body and greater cornu of the hyoid bone.
Relations. By its external surface, with the Sterno-hyoid and Omo-hyoid
muscles. By its internal surface, with the thyroid cartilage, the thyro-hyoid
membrane, and the superior laryngeal vessels and nerve.
The Omo-hyoid 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
forms a flat, narrow fasciculus, which inclines forwards across the lower part of
the neck; behind the Sterno-mastoid muscle, where it becomes tendinous, it changes
its direction, forming an obtuse angle, and ascends almost vertically upwards, close
to the outer border of the Sterno-hyoid, to be inserted into the lower border of
the body of the os hyoides, just external to the insertion of the Sterno-hyoid.
The tendon of this muscle, which varies much in its length and form in different
subjects, is held in its position by a process of the deep cervical fascia, which
includes it in a sheath, and is prolonged down, to be attached to the cartilage
of the 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 are the posterior superior
or suboccipital, and the posterior inferior or subclavian; the two anterior, the
anterior superior or superior carotid, and the anterior inferior or inferior carotid
triangle.
Relations. By its superficial surface, with the Trapezius, Subclavius, the
clavicle, the Sterno-mastoid, deep cervical fascia, Platysma, and integument. By
its deep surface, with the Scaleni, brachial plexus, sheath of the common carotid
artery, and internal jugular vein, the descendens noni nerve, 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
noni and communicans noni.
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 backwards, and to one or
the other side. These muscles are also tensors of the cervical fascia. The Thyro-
hyoid may act as an elevator of the thyroid cartilage, when the hyoid bone ascends,
drawing upwards the thyroid cartilage behind the os hyoides.
3. Supra-hyoid Begion (figs. 153 and 154).
Elevators of the Os Hyoides ; 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 backwards, and retained in that position. On the removal of the deep fascia,
tho muscles are at once exposed.
SUPRA-HYOID REGION. 259
The Digastric consists of two fleshy bellies united by an intermediate 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, longer than the anterior, arises from the di-
gastric groove on the inner side of the mastoid process of the temporal bone, and
passes downwards, forwards, and inwards. The anterior belly, being reflected
upwards and forwards, is inserted into a depression on the inner side of the lower
border of the jaw, close to the symphysis. The tendon of the muscle perforates
the Stylo-hyoid, and is held in connection with the side of the body of the hyoid
bone by an aponeurotic 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 beneath it.
The Digastric muscle divides the anterior superior triangle of the neck into two
smaller triangles. The upper or submaxillary triangle is bounded, above, by the
lower jaw, and mastoid process ; below, by the two bellies of the Digastric muscle:
the lower or superior carotid triangle being bounded, above, by the posterior
belly of the Digastric ; behind, by the Sterno-mastoid ; below, by the Omo-hyoid.
Relations. By its superficial surface, with the Platysma, Sterno-mastoid and
Trachelo-mastoid, part of the Stylo-hyoid muscle, and the parotid and submaxillary
glands. By its deep surface, the anterior belly lies on the Mylo-hyoid ; the pos-
terior belly on the Stylo-glossus, Stylo-pharyngeus, and Hyo-glossus muscles, the
external carotid and its lingual and facial branches, the internal carotid, internal
jugular vein, and hypoglossal nerve.
The Stylo-hyoid is a small, slender muscle, lying in front of, and above, the
posterior belly of the Digastric. It arises from the middle of the outer surface
of the styloid process ; and, passing downwards and forwards, is inserted into the
body of the hyoid bone, just at its junction with the greater cornu, and immedi-
ately above the Omo-hyoid. This muscle is perforated, near its insertion, by the
tendou of the Digastric.
Relations. The same as the posterior belly of the Digastric.
The Digastric and Stylo-hyoid should be removed, in order to expose the next muscle.
The Mylo-hyoid 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, from the symphysis in front, to the last molar tooth behind.
The posterior fibres pass obliquely forwards, to be inserted into the body of the
os hyoides. The middle and anterior fibres are inserted into a median fibrous
raphe, where they join at an angle with the fibres of the opposite muscle. This
median raphe is sometimes wanting; the muscular fibres of the two sides are then
directly continuous with one another.
Relations. By its cutaneous surface, with the Platysma, the anterior belly .of the
Digastric, the supra-hyoid fascia, the submaxillary gland, and submental vessels.
By its deep or superior surface, with the Genio-hyoid, part of the Hyo-glossus, and
Stylo-glossus muscles, the lingual and gustatory nerves, the sublingual gland, and
the buccal mucous membrane. Wharton's duct curves round its posterior border
in its passage to the mouth.
Dissection. The Mylo-hyoid should now be removed, in order to expose the muscles which lie
beneath; this is effected by detaching 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 'is a narrow slender muscle, situated immediately beneath the
inner border of the preceding. It arises from the inferior genial tubercle on the
inner side of the symphysis of the jaw, and passes downwards and backwards, to
260 MUSCLES AND FASCIAE.
be inserted into the anterior surface of the body of the os hyoides. 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 on the Genio-hyo-glossus.
Nerves. The Digastric is supplied, its anterior belly by the mylo-hyoid branch
of the inferior dental, its posterior belly by the facial ; the Stylo-hyoid, 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 deglu-
tition ; 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 upwards and forwards by the anterior belly of the Digastric,
the Mylo-hyoid, and Genio-hyoid muscles. In the second act, when the mass is
passing 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 upwards and backwards by the posterior belly of the
Digastric and Stylo-hyoid muscles, which assist in preventing the return of the
morsel into the cavity of the mouth.
4. Lingual Eegion.
Genio-hyo-glossus. Lingualis.
Hyo-glossus. Stylo-glossus.
Palato-glossus.
Dissection. After completing' the dissection of the preceding muscles, saw through the lower
jaw just external to the symphysis. The tongue should then be drawn forwards with a hook,
and its muscles, which are thus put on the stretch, may be examined.
The Genio-hyo-glossus has received its name from its triple attachment to the
chin, hyoid bone, and tongue; it is a thin, flat, triangular muscle, placed vertically
in 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 sym-
physis of the chin, immediately above the Genio-hyoid ; from this point, the muscle
spreads out in a fan-like form, the inferior fibres passing downwards to be inserted
into the upper part of the body of the hyoid bone, a few being continued into the
side of the pharynx ; the middle fibres passing backwards, and the superior ones
upwards and forwards, to be attached to the whole length of the under surface of
the tongue, from the base to the apex.
Relations. By its internal surface, it is in contact with its fellow of the opposite
side, from which it is separated, at the back part of the tongue, by a fibro-cellular
structure, which extends forwards through the middle of the organ. By its
external surface, with the Lingualis, Hyo-glossus, and Stylo-glossus, the lingual
artery and hypoglossal nerve, the gustatory nerve, and sublingual gland. By its
upper border, with the mucous membrane of the floor of the mouth. By its lower
border, with the Genio-hyoid.
The Hyo-glossus is a thin, flat, quadrilateral muscle, arising from the side of
the body, the lesser cornu, and whole length of the greater cornu of the hyoid
bone, and, passing almost vertically upwards, is inserted into the side of the tongue,
between the Stylo-glossus and Lingualis. Those fibres of this muscle which arise
from the body are directed upwards and backwards, overlapping those from the
greater cornu, which are directed obliquely forwards. Those from the lesser cornu
extend forwards and outwards along the side of the tongue, under cover of the
portion arising from the body.
LINGUAL REGION.
261
The difference in the direction of the fibres of this muscle, and their separate
origin from different segments of the hyoid bone, led Albinus and other anato-
mists to describe it as three muscles, under the names of the Basio-glossus, the
Cerato-glossus, and the Chondro-glossus.
Relations. By its external surface, with the Digastric, the Stylo-hyoid, Stylo-
glossus, and Mylo-hyoid muscles, the gustatory and hypoglossal nerves, Wharton's
duct, and the sublingual gland. By its deep surface, with the Genio-hyo-glossus,
Lingualis, and the Middle constrictor, the lingual vessels, and the glosso-pharyn-
geal nerve.
The Lingualis is a longitudinal band of muscular fibres, situated on the under
surface of the tongue, lying in the interval between the Hyo-glossus and the
Genio-hyo-glossus, and extending from the base to the apex of that organ.
Posteriorly, some of its fibres are lost in the base of the tongue, and others are
attached to the hyoid bone. It blends with the fibres of the Stylo-glossus, in front
Fig. 155. — Muscles of the Tongue. Left Side.
of the Hyo-glossus, and is continued forwards as far as the apex of the tongue.
It is in relation, by its under surface, with the ranine artery.
The Stylo-glossus, the shortest and smallest of the three styloid muscles, arises
from the anterior and outer side of the styloid process, near its centre, and from
the stylo-maxillary ligament, to which its fibres, in most cases, are attached by a
thin aponeurosis. Passing downwards and forwards, so as to become nearly hori-
zontal in its direction, it divides upon the side of the tongue into two portions :
one longitudinal, which is inserted along the side of the tongue, 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 downwards, with the parotid
gland, the Internal pterygoid muscle, the sublingual gland, the gustatory nerve
202
MUSCLES AND FASCIA.
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, although one of the muscles
of the tongue, serving to draw its base upwards 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 supplied by the palatine branches of Meckel's
ganglion ; the Lingualis, by the chorda tympani ; the remaining muscles of this
group, by the hypoglossal.
Actions. The movements of the tongue, although numerous and complicated,
may easily be understood by carefully considering the direction of the fibres of the
muscles of this organ. The Genio-hyo-glossi, by means of their posterior and
inferior fibres, draw upwards the hyoid bone, bringing it and the base of the tongue
forwards, so as to protrude the apex from the mouth. The anterior fibres will
restore it to its original position by retracting the organ within the mouth. The
whole length of these two muscles acting along the middle line of the tongue
will draw it downwards, so as to make it concave from before backwards, forming
a channel along which fluids may pass towards the pharynx, as in sucking. The
Hyo-glossi muscles draw down the sides of the tongue, so as to render it convex
from side to side. The Linguales, by drawing downwards the centre and apex
of the tongue, render it convex from before backwards. The Palato-glossi draw
the base of the tongue upwards, and the Stylo-glossi upwards and backwards.
5. Phakyngeal Kegion.
Constrictor Inferior. Constrictor Superior.
Constrictor Medius. Stylo-pharyngeus.
Palato-pharyngeus.
Fig. 156. — Muscles of the Pharynx. External View. Dissection (fig. 156). In order
to examine the muscles of the
pharynx, cut through the trachea
and oesophagus just above the
sternum, and draw them upwards
by dividing the loose areolar tis-
sue connecting the pharynx with
the front of the vertebral column.
The parts being drawn well for-
wards, the edge of the saw should
be applied immediately behind
the styloid processes, and the
base of the skull sawn through
from below upwards. The
pharynx and mouth should then
be stuffed with tow, in order to
distend its cavity and render the
muscles tense and easier of dis-
section.
The Inferior Constrictor,
the most superficial and
thickest of the three con-
strictors, arises from the
side of the cricoid and thy-
roid cartilages. To the
cricoid cartilage it is at-
tached in the interval be-
tween the Crico-thyroid, in
front, and the articular facet
for the thyroid cartilage be-
hind. To the thyroid car-
tilage, it is attached to the oblique line on the side of the great ala, the carti-
PHARYNGEAL REGION". 2C3
laginous surface behind it, nearly as far as its posterior border, and to the
inferior cornu. From these attachments, the fibres spread backwards and
inwards, 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
constrictor. The superior laryngeal nerve passes near the upper border, and the
inferior or recurrent laryngeal beneath the lower border of this muscle, previous
to their entering the larynx.
Relations. It is covered by a dense cellular membrane which surrounds the
entire pharynx. Behind, it lies on the vertebral column and the Longus colli.
Laterally, it is in relation 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-pharyngeus, and the mucous membrane of the
pharynx.
The Middle Constrictor is a flattened, fan-shaped muscle, smaller than the pre-
ceding, and situated on a plane anterior to it. It arises from the whole length 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 descending
beneath the Inferior constrictor, the middle fibres passing transversely, and the
upper fibres ascending to cover in the Superior constrictor. It is inserted into
the posterior median fibrous raphe, blending in the middle line with the fibres of
the opposite muscle.
Relations. This muscle is separated from the Superior constrictor by the glosso-
pharyngeal nerve and the Stylo-pharyngeus muscle ; and from the Inferior con-
strictor, by the superior laryngeal nerve. Behind, it lies on the vertebral column,
the Longus colli, and the Rectus anticus major. On each side it is in relation
with the carotid vessels, the pharyngeal plexus, and some lymphatic glands. Near
its origin, it is covered by the Hyo-glossus, from which it is separated by the
lingual artery. It covers in the Superior constrictor, the Stylo-pharyngeus, the
Palato-pharyngeus, and the mucous membrane.
The Superior Constrictor 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 margin of the 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 ptery go-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 in connection with the Genio-hyo-glossus. From these
points, the fibres curve backwards, 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. Its 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
fibrous membrane.
Relations. By its outer surface, with the vertebral column, the carotid vessels,
the internal jugular vein, the three divisions of the eighth and ninth nerves, the
Middle constrictor whioh overlaps it, and the Stylo-pharyngeus. It covers the
Palato-pharyngeus and the tonsil, and is lined by mucous membrane.
The Stylo-pharyngeus is a long, slender muscle, round above, broad and thin
below. It arises from the inner side of the base of the styloid process, passes
downwards along the side of the pharynx between the Superior and Middle con-
strictors, and, spreading out beneath the mucous membrane, some of its fibres are
lost in the Constrictor muscles, and others, joining with the Palato-pharyngeus,
are inserted into the upper border of the thyroid cartilage. The glossopharyngeal
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 external carotid
artery, the parotid gland, and the Middie constrictor. Internally, with the internal
264
MUSCLES AND FASCIAE.
carotid, the internal jugular vein, the Superior constrictor, Palato-pharyngeus and
mucous membrane.
Nerves. The muscles of this group are supplied by branches from the pharyn-
geal plexus and glosso-pharyngeal nerve ; and the Inferior constrictor, by an addi-
tional branch from the external laryngeal nerve.
Actions. When deglutition is about to be performed, the pharynx is drawn
upwards 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 upwards and outwards
the sides of this cavity, the breadth of the pharynx in the antero-posterior direction
being increased by the larynx and tongue being carried forwards 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
downwards into the oesophagus. The pharynx also exerts an important influence
in the modulation of the voice, especially in the production of the higher tones.
6. Palatal Eegiox.
Azygos Uvulae.
Palato-glossus.
Levator Palati.
Tensor Palati.
Palato-pharyngeus.
Dissection (fig. 157). 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 care-
fully removed from the posterior surface of the soft palate, and the muscles of this part are at
once exposed.
Fig. 157. — Muscles of the Soft Palate ; the Pharynx being laid open from behiud.
PALATAL REGION". 265
The Levator Palati is a long, thick, rounded muscle, placed on the outer side
of the posterior aperture of the nares. It arises from the under surface of the
apex of the petrous portion of the temporal bone, and from the adjoining carti-
laginous portion of the Eustachian tube, and after passing into the pharynx, above
the upper concave margin of the Superior constrictor, it descends obliquely
downwards and inwards, its fibres spreading out in the posterior surface of 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. Inter-
nally, it is lined by the mucous membrane of the pharynx. Posteriorly, with the
mucous lining of the soft palate. This muscle must be removed and the pterygoid
attachment of the Superior constrictor dissected away, in order to expose the next
muscle.
The Circumflexus or Tensor Palati is a broad, thin, riband-like muscle, placed
on the outer side of the preceding, and consisting of a vertical and a horizontal
portion. The vertical portion arises by a broad, thin, and fiat lamella from the
scaphoid fossa at the base of the internal pterygoid plate, its origin extending as
far back as the spine of the sphenoid ; it also arises from the anterior aspect of
the cartilaginous portion of the Eustachian tube ; descending vertically between
the internal pterygoid plate and the inner surface of the Internal pterygoid muscle,
it terminates in a tendon which winds round the hamular process, being retained
in this situation by a tendon of origin of the Internal pterygoid muscle, and
lubricated by a bursa. The tendon or horizontal portion then passes horizontally
inwards, and expands into a broad aponeurosis on the anterior surface of the soft
palate, which unites in the median line with the aponeurosis of the opposite
muscle, the fibres being attached in front to the transverse ridge on the posterior
border of 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 Superior constrictor, and the internal
pterygoid plate. In the soft palate its aponeurotic expansion is anterior to that
of the Levator palati, being covered by mucous membrane.
The Azygos Uvulse is not a single muscle as implied by its name, but a pair of
narrow cylindrical fleshy fasciculi, placed side by side in 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 mucous membrane.
The two next muscles are exposed by removing the mucous membrane which covers the pillars
of the soft palate throughout nearly their whole extent.
The Palato-glossus or Constrictor Isthmi Faucium is a small fleshy fasciculus,
narrower in the middle than at either extremity, forming, with the mucous mem-
brane 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
forwards and outwards in front of the tonsil, is inserted into the side and dorsum
of the tongue, where it blends with the fibres of the Stylo-glossus muscle. In the
soft palate, the fibres of this muscle are continuous with those of the opposite side,
The Palato-pharyngeus 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 separated from the preceding 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.
The anterior fasciculus, the thickest, enters the soft palate between the Levator
palati and Tensor palati, and joins in the middle line the corresponding part of
the opposite muscle; the posterior fasciculus lies in contact with the mucous mem-
brane, and also joins with the corresponding muscle in the middle line. Passing
266 MUSCLES AND FASCIAE.
outwards and downwards behind the tonsil, it joins the Stylo-pharyngeus, and is
inserted with it 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 anterior and posterior surfaces are covered by
mucous membrane, from which it is separated by a layer of palatine glands. By
its superior border, it is in relation with the Levator 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.
Nerves. The Tensor palati is supplied by a branch from the otic ganglion; the
Levator palati, and Azygos uvulre, by the facial, through the connection of its
trunk, with the Vidian, by the petrosal nerves ; the other muscles, by the palatine
branches of Meckel's ganglion.
Actions. During ike first act 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 forwards under it ; the epiglottis is pressed over the superior
aperture of the larynx, and the morsel glides past it. This constitutes the second
act of deglutition ; then the Palato-glossi muscles, the constrictors of the fauces,
contract behind it ; the soft palate is slightly raised by the Levator palati, and
made tense by the Tensor palati ; and the Palato-pharyngei contract, and 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 pharynx or the
posterior nares; at the same time, the latter muscles form an inclined plane,
directed obliquely downwards and backwards, along which the morsel descends
into the lower part of the pharynx.
Surgical Anatomy. The muscles of the soft palate should be carefully dissected, the relations
thej- bear to the surrounding parts especially examined, and their action attentively studied upon
the dead subject, as the surgeon is required to divide one or more of these muscles in the opera-
tion of staphyloraphy. Mr. Fergusson has shown, that in the congenital deficiency, called cleft
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 has, consequently,
recommended the division of these muscles as one of the most important steps in the operation :
by these means, the flaps are relaxed, lie perfectly loose and pendulous, and are easily brought
and retained in apposition. The Palato-pharyngei may be divided by cutting across the poste-
rior 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 flap being put upon the stretch, a double-edged
knife is passed through the soft palate, 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 sweep-
ing 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 per-
formed on the dead body, and the parts afterwards dissected, the Levator palati will be found
completely divided.
7. Anterior Vertebral Eegion.
Eectus Capitis Anticus Major. Eectus Lateralis.
Eectus Capitis Anticus Minor. Longus Colli.
The Rectus Capitis Anticus Major (fig. 158), broad and thick above, narrow
beiow, appears like a continuation upwards of the Scalenus 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 towards
its fellow of the opposite side, to be inserted into the basilar process of the occi-
pital bone.
Relations. By its anterior surface, with the pharynx, the sympathetic nerve,
and the sheath inclosing the carotid artery, internal jugular vein, and pneumo-
ANTERIOR VERTEBRAL REGION.
2CT
gastric nerve. By its posterior surface, with the Longus colli, the Rectus anticus
minor, and the upper cervical vertebrse.
The Rectus Capitis Anticus Minor is a short flat muscle, situated immediately
beneath 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 ; passing
obliquely upwards and inwards, it is inserted into the basilar process immediately
behind the preceding muscle.
Relations. By its anterior surface, with the Rectus anticus major. By its
posterior surface, with the front of the occipito-atlantal articulation. Externally,
with the superior cervical ganglion of the sympathetic.
The Rectus Lateralis is a short, flat muscle, situated between the transverse
process of the atlas and the jugular process of the occipital bone. It 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
posterior surface, with the vertebral artery.
Fig. 158. — The Pre-vertebral Muscles.
The Longus Colli is a long, flat muscle, situated on the anterior surface of the
spine, between the atlas and the third dorsal vertebra, being broad in the middle,
narrow and pointed at each extremity. It 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 vertebrae ; and, ascending obliquely
inwards, is inserted by a narrow tendon into the tubercle on the anterior arch of
the atlas.
The inferior oblique portion, the smallest part of the muscle, arises from the
268 MUSCLES AND FASCIAE.
bodies of the first two or three dorsal vertebrae ; and, passing obliquely outwards,
is inserted into the transverse processes of the fifth and sixth cervical vertebras.
The vertical portion lies directly on the front of the spine, and is extended
between the bodies of the lower three cervical and the upper three dorsal vertebras
below, and the bodies of the second, third, and fourth cervical vertebras above.
Relations. By its anterior surface, with the pharynx, the oesophagus, sympathetic
nerve, the sheath of the carotid artery, internal jugular vein, and pneumogastric
nerve, inferior thyroid artery, and recurrent laryngeal nerve. By its posterior
surface, with the cervical and dorsal 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. Lateral Vertebral Eegion.
Scalenus Anticus. Scalenus Medius.
Scalenus Posticus.
The Scalenus Antims is a conical-shaped muscle, situated deeply at the side of
the neck, behind the Sterno-mastoid. It arises by a narrow, flat tendon from the
tubercle on the inner border and upper surface of the first rib ; and, ascending
vertically upwards, is inserted into the anterior tubercles of the transverse pro-
cesses of the third, fourth, fifth, and sixth cervical vertebrae. The lower part of
this muscle separates the subclavian artery and vein ; the latter being in front,
and the former, with the brachial plexus, behind.
Relations. It is covered by the clavicle, the Subclavius, Sterno-mastoid, and
Omo-hyoid muscles, the transversalis colli, and ascending cervical arteries, the
subclavian vein, and the phrenic nerve. By its posterior surface, with the pleura,
the subclavian artery, and brachial plexus of nerves. It is separated from the
Longus colli, on the inner side, by the subclavian artery.
The Scalenus Medius, the largest and longest of the three Scaleni, arises, by
a broad origin, from the upper surface of the first rib, behind the groove for the
subclavian artery, as far back as the tubercle ; and, ascending along the side of
the vertebral column, is inserted, by separate tendinous slips, into the posterior
tubercles of the transverse processes of the lower six cervical vertebrae. It is
separated from the Scalenus anticus by the subclavian artery below, and the
cervical nerves above.
Relations. By its external surface, with the Sterno-mastoid ; it is crossed by
the clavicle, and Omo-hyoid muscle. To its outer side, are the Levator anguli
scapulae, and the Scalenus posticus muscles.
The Scalenus posticus, the smallest of the three Scaleni, arises by a thin tendon
from the outer surface of the second rib, behind the attachment of the Serratus
magnus, and, enlarging as it ascends, is inserted, by two or three separate tendons,
into the posterior tubercles of the transverse processes of the lower two or three
cervical vertebrae. 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 Rectus capitis anticus minor are
supplied by the suboccipital and deep branches of the cervical plexus ; the Rectus
lateralis, by the suboccipital ; and the Longus colli and Scaleni, by branches from
the lower cervical nerves.
Actions. The Rectus anticus major and Rectus anticus minor are the direct
antagonists of those placed at the back of the neck, serving to restore the head to
its natural position when drawn backwards by the posterior muscles. 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 will flex and slightly
rotate the cervical portion of the spine. The Scaleni muscles, taking their fixed
point from below, draw down the transverse processes of the cervical vertebrae,
flexing the spinal column to one or the other side. If the muscles of both sides
act, the spine will be kept erect. When taking their fixed point from above,
they elevate the first and second ribs, and are, therefore, inspiratory muscles.
MUSCLES OF THE BACK.
MUSCLES AND FASCIAE OF THE TEUNK.
The Muscles of the Trunk may be subdivided into four groups :—
1. Muscles of the Back. 3. Muscles of the Thorax.
2. Muscles of the Abdomen. 4. Muscles of the Perineum.
Muscles of the Back.
The Muscles of the Back are very numerous, and may be subdivided into five
layers : —
First Layer.
Cervical region.
Trapezius. „
Latissimus dorsi. Cervicalis ascendens.
Transversahs colli.
Second Layer. Trachelo-mastoid.
Levator anguli scapulae. Complexus.
Ehomboideus minor. Jiyenter ^rvicis.
Ehomboideus major. Spinalis cervicis.
Third Layer.
Serratus posticus superior. Fifth Layer.
Serratus posticus inferior.
Splenius capitis. Semi-spinalis dorsi.
Splenius colli. Semi-spinalis colli.
Fourth Layer. Multifidus spina?.
_, 7 7 7 7 . Kotatores spmse.
sacral and lumbar regions. Supra-spinales
Erector spina?. Inter-spinales.
,_. , . Extensor coccysris.
Dorsal region. Intertransverses. _
Sacro-lumbalis. Eectus posticus major.
Musculus accessorius ad sacro-lumbalem. Eectus posticus minor.
Longissimus dorsi. Obliquus superior.
Spinalis dorsi. Obliquus inferior.
First Layer.
Trapezius. Latissimus Dorsi.
Dissection (fig. 159). The body should be placed in the prone position, with the arms ex-
tended over the sides of the table, and the chest and abdomen supported by several blocks, so
as to render the muscles tense. An incision should then be made along the middle line of the
back, from the occipital protuberance to the coccyx. From the upper end of this, a transverse
incision should extend to the mastoid process ; and from the lower end, a third incision should
be made along the crest of the ilium to about its middle. This large intervening space, for con-
venience of dissection, should be subdivided by a fourth incision, extending obliquely from the
spinous process of the last dorsal vertebra, upwards and outwards, to the acromion process.
This incision corresponds with the lower border of the Trapezius muscle. The flaps of integu.
ment should then be removed in the direction shown in the figure in the next page.
The Trapezius is a broad, flat, triangular muscle, placed immediately beneath
the skin, and covering the upper and back part of the neck and shoulders. It
arises from the inner third of the superior curved line of the occipital bone ; from the
ligamentum nucha?, the spinous process of the seventh cervical, and those of all the
dorsal vertebra? ; and from the corresponding portion of the supra-spinous ligament.
From this origin, the superior fibres proceed downwards and outwards ; the inferior
ones, upwards and outwards ; and the middle fibres, horizontally ; and are inserted,
the superior ones, into the outer third of the posterior border of the clavicle ; the
middle fibres, into the upper margin of the acromion process, and into the whole
270
MUSCLES AND FASCIAE.
Fig. 159. — Dissection of the Muscles of the Back.
length of the upper border of the spine of the scapula; the inferior fibres converge
near the scapula, and are attached to a triangular aponeurosis, which glides over
a smooth surface at the inner extremity of
the spine, and is inserted into a tubercle
in immediate connection with its outer
part. 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 aponeurosis. At its origin
from the spines of the vertebrae, it is
connected by means of a broad semi-
elliptical aponeurosis, which occupies the
space between the sixth cervical and the
third dorsal vertebras, and forms, with
the aponeurosis of the opposite muscle, a
tendinous ellipse. The remaining part of
the origin is effected by numerous short
tendinous fibres. If the Trapezius is dis-
sected 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 dorsal ver-
tebra.
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.
Relations. By its superficial surface, with the integument to which it is closely
adherent above, but separated below by an aponeurotic lamina. By its deep sur-
face, in the neck, with the Complexus, Splenius, Levator anguli scapulas, and
Ehomboideus minor ; in the back, with the Khomboideus major, Supra-spinatus,
Infra-spinatus, a small portion of the Serratus posticus superior, the intervertebral
aponeurosis which separates it from the Erector spinas, and with the Latissimus
dorsi. The spinal accessory nerve passes beneath the anterior border of this
muscle, near the clavicle. The outer 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 nuchse (fig. 160) is a thin band of condensed cellulo-fibrous
membrane, placed in the line of union between the two Trapezii in the neck. It
extends from the external occipital protuberance to the spinous process of the
seventh cervical vertebra, where it is continuous with the supra-spinous ligament.
From its anterior surface a fibrous slip is given off to the spinous process of
each of the cervical vertebras, excepting the atlas, 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
lower half of the dorsal regions, and is gradually contracted into a narrow fasci-
culus at its insertion into the humerus. It arises by an aponeurosis from the
spinous processes of the sixth inferior dorsal, from those of the lumbar and sacral
OF THE BACK.
271
Fig. 160. — Muscles of the Back. On the Left Side is exposed the First Layer ;
on the Right Side, the Second Layer and part of the Third.
2Y2 MUSCLES AND FASCIAE.
vertebras, and from the supra-spinous ligament. Over the sacrum, the aponeurosis
of this muscle blends with the tendon of the Erector spinas. 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, being interposed
between similar processes of the External oblique muscle. From this extensive
origin the fibres pass in different directions, the upper ones horizontally, the
middle ones obliquely upwards, and the lower ones vertically upwards, so" as to
converge and form a thick fasciculus, which crosses the inferior angle of the
scapula, and occasionally receives a few fibres 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 quadri-
lateral 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, above the insertion 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 inter-
posed between the muscle and the inferior angle of the scapula.
A muscular slip, varying from 3 to 4 inches in length, and from | to f of an inch broad, occa-
sionally arises from the upper edge of the Latissimus dorsi, about the middle 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 Ooraco-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 liga-
ture, and may mislead the surgeon during the operation. It may be easily recognized by the
transverse direction of its fibres. Dr. Struthers found it in 8 out of 105 subjects, occurring
7 times on both sides.
Relations. Its superficial surface is subcutaneous, excepting at its upper part,
where it is covered by the Trapezius. By its deep surface, it is in relation with
the Erector spinas, the Serratus posticus inferior, lower Intercostal muscles and
ribs, the Serratus magnus, inferior angle of the scapula, Rhomboideus major,
Infra-spinatus, and Teres major. Its outer margin is separated, below, from the
External oblique, by a smaller triangular interval; and another triangular interval
exists between its upper border and the margin of the Trapezius, in which the
Intercostal and Rhomboideus major muscles are exposed.
Nerves. The Trapezius is supplied by the spinal accessory and cervical plexus;
the Latissimus dorsi, by the subscapular nerves.
Second Layer.
Levator Anguli Scapulas. Rhomboideus Minor.
Rhomboideus Major.
Dissection. The Trapezius must be removed in order to expose the next layer ; to effect this,
the muscle must be detached from its attachment to the clavicle and spine of the scapula, and
turned back towards the spine.
The Levator Anguli Scapulse is situated at the back part and side of the neck.
It arises by four tendinous slips from the posterior tubercles of the transverse
processes of the three or four upper cervical vertebras ; these becoming fleshy are
united so as to form a flat muscle, which, passing downwards and backwards, 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 colli,
Cervicalis ascendens, and Serratus posticus superior, and with the transverse cer.
vical and posterior scapular arteries.
The Rhomboideus Minor arises from the ligamentum nuchas, and spinous pro
cesses of the seventh cervical and first dorsal vertebras. Passing downwards and
OF THE BACK. 273
outwards, 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
Ehomboideus major by a slight cellular interval.
The Ehomboideus Major is situated immediately below the preceding, the adja*
cent margins of the two being occasionally united. It arises by tendinous fibres
from the spinous processes of the four or five upper dorsal vertebrae and the supra-
spinous ligament, and is inserted into a narrow, tendinous arch, attached, above, to
the triangular surface near 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 their superficial surface, with the integument, and Trapezius ;
the Ehomboideus major, with the Latissimus dorsi. By their deep surface, with
the Serratus posticus superior, posterior scapular artery, part of the Erector spinae,
the Intercostal muscles and ribs.
Nerves. These muscles are supplied by branches from the fifth cervical nerve,
and additional filaments from the deep branches of the cervical plexus are distrib-
uted to the Levator anguli scapulae.
Actions. The movements effected by the preceding muscles are numerous, as
may be conceived from their extensive attachment. If the head is fixed, the upper
part of the Trapezius will elevate the point of the shoulder, as in supporting
weights ; when the middle and lower fibres are brought into action, partial rotation
of the scapula upon the side of the chest is produced. If the shoulders are fixed,
both Trapezii acting together will draw the head directly backwards, or, if only
one acts, the head is drawn to the corresponding side.
The Latissimus dorsi, when it acts upon the humerus, draws it backwards and
downwards, and at the same time rotates it inwards. 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
conspire with the Abdominal and great Pectoral muscles in drawing the whole
trunk forwards, as in climbing or walking on crutches.
The Levator anguli scapulae raises the superior angle of the scapula after it has
been depressed by the lower fibres of the Trapezius, whilst the Ehomboid muscles
carry the inferior angle backwards and upwards, thus producing a slight rotation
of the scapula upon the side of the chest. If the shoulder be fixed, the Levator
scapulae may incline the neck to the corresponding side. The Ehomboid muscles,
acting together with the middle and inferior fibres of the Trapezius, will draw the
scapula directly backwards towards the spine.
Third Layer.
Serratus Posticus Superior. Serratus Posticus Inferior.
c i • ( Splenius Capitis.
Splenius < Qri • n fr
^ ( Splenius Colli.
Dissection. The third layer of muscles is brought into view by the entire removal of the pre.
ceding, together with the Latissimus dorsi. To effect this, the Levator anguli scapulas and
Rhomboid muscles should be detached near their insertion, and reflected upwards, thus exposing
the Serratus posticus superior ; the Latissimus dorsi should then be divided in the middle by a
vertical incision carried from its upper to its lower part, and the two halves of the muscle reflected.
The Serratus Posticus Superior is a thin, flat muscle, quadrilateral in form,
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 dorsal vertebrae. Inclining downwards and
outwards, 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.
18
2U MUSCLES AND FASCIAE.
Relations. By its superficial surface, with the Trapezius, Rhomboidei, and
Serratus magnus. By its deep surface, with the Splenius, upper part of the
Erector spinas, Intercostal muscles and ribs.
The Serratus Posticus Inferior is situated opposite the junction of the dorsal
and lumbar regions, is of an irregularly quadrilateral form, broader than the pre-
ceding, and separated from it by a considerable interval. It arises by a thin
aponeurosis from the spinous processes of the last two dorsal and two or three
upper lumbar vertebrae, and from the interspinous ligaments. Passing obliquely
upwards and outwards, 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.
Relations. By its superficial surface, it is covered by the Latissimus dorsi, with
the aponeurosis of which its own aponeurotic origin is inseparably blended. By
its deep surface, with the posterior aponeurosis of the Transversalis, the Erector
spinas, ribs and Intercostal muscles. Its upper margin is continuous with the
vertebral aponeurosis.
The vertebral ajjoneurosis is a thin aponeurotic lamina, extending along the
whole length of the back part of the thoracic region, serving to bind down the
Erector spinas, and separating it 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 dorsal vertebras ; externally, to the angles of the ribs ; and
below, to the upper border of the Inferior serratus and tendon of the Latissimus
dorsi ; above, it passes beneath the Splenius, and blends with the deep fascia of
the neck.
The Serratus posticus superior should now be detached from its origin and turned outwards,
when the Splenius muscle will be brought into view.
The Splenius is situated at the back of the neck and upper part of the dorsal
region. At its origin, it is a single muscle, narrow and pointed in form ; but it
soon becomes broader, and divides into two portions, which have separate inser-
tions. It arises, by tendinous fibres, from the lower half of the ligamentum
nuchas, from the spinous processes of the last cervical and of the six upper dorsal
vertebras, and from the supra-spinous ligament. From this origin, the fleshy
fibres proceed obliquely upwards and outwards, forming a broad flat muscle, which
divides as it ascends into two portions, the Splenius capitis and Splenius colli.
The splenius capitis is inserted into the mastoid process of the temporal bone, and
into the rough surface on the occipital bone beneath the superior curved line.
The splenius colli is inserted, by tendinous fasciculi, into the posterior tubercles
of the transverse processes of the three or four upper cervical vertebras.
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
at its insertion by the Sterno-mastoid. By its deep surface, with the Spinalis
dorsi, Longissimus dorsi, Semi-spinalis colli, Complexus, Trachelo-mastoid, and
Transversalis colli.
Nerves. The Splenius and Superior serratus are supplied from the externnl
posterior branches of the cervical nerves; the Inferior serratus, from the external
branches of the dorsal nerves.
Actions. The Serrati are respiratory muscles acting in antagonism to each
other. The Serratus posticus superior elevates the ribs and is, therefore, an inspi-
ratory muscle; while the Serratus inferior draws the lower ribs downwards, and
is a muscle of expiration. This muscle is also probably a tensor of the vertebral
aponeurosis. The Splenii muscles of the two sides, acting together, draw the
head directly backwards, assisting the Trapezius and Complexus ; acting sepa-
rately, they draw the head to one or the other side, and slightly rotate it, turning
OF THE BACK.
275
the face to the same side. They also assist in supporting the head in the erect
position.
Fig. 161. — Muscles of the Back. Deep Layers.
: tit I i
MULTiriDUS SPINA
if* Dorsal
' HjZumbar
ffSacralX.
£76 MUSCLES AND FASCIA.
Foukth Layer.
Sacral and Lumbar Regions. Cervical Region.
Erector spinae. Cervicalis ascendens.
Dorsal Region. Transversalis colli.
Sacro-lumbalis. Trachelo-mastoid.
Musculus accessorius ad sacro-lumbalem. Complexus.
Longissimus dorsi. Biventer cervicis.
Spinalis dorsi. Spinalis cervicis.
Dissection. To expose the muscles of the fourth layer, the Serrati and vertebral aponeurosis
should be entirely removed. The Splenius may then be detached by separating its attachments
to the spinous processes, and reflecting it outwards.
The Erector Spinse (fig. 161), and its prolongations in the dorsal and cervical
regions, fill up the vertebral groove on each side of the spine. It is covered in
the lumbar region by the lumbar aponeurosis; in the dorsal region, by the Serrati
muscles and the vertebral aponeurosis ; and in the cervical region, by a layer of
cervical fascia continued beneath the Trapezius. 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, it becomes enlarged, and forms a large fleshy
mass. In the dorsal region, it subdivides into two parts, which gradually
diminish in size as they ascend to be inserted into the vertebras and ribs, and are
gradually lost in the cervical region, where a number of special muscles are
superadded, which are continued upwards to the head, which they support upon
the spine.
The Erector spinas arises from the sacro-iliac groove, and 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 three lower
dorsal vertebrae, and the supra-spinous ligament ; externally, to the back part of
the inner lip of the crest of the ilium, and to the series of eminences on the pos-
terior part of the sacrum, representing the transverse processes, where it blends
with the great sacro-sciatic ligament. 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 fascia of the Transversalis muscle. Opposite the
last rib, it divides into two parts, the Sacro-lumbalis, and the Longissimus dorsi.
* The Sacro-lumbalis (Ilio-costalis), the external and smaller portion of the
Erector spinae, is inserted, by six or seven flattened tendons, into the angles
of the six lower ribs. If this muscle is reflected outwards, 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 Sacro-lumbalis is continued upwards, to be
connected with the upper ribs, and with the cervical portion of the spine,
forming two additional muscles, the Musculus accessorius and the Cervicalis
ascendens.
The Musculus accessorius ad sacro-lumbalem arises by separate flattened tendons,
from the angles of the six lower ribs ; these become muscular, and are finally in-
serted, by separate tendons, into the angles of the six upper ribs.
The Cervicalis ascendens is the continuation of the Accessorius upwards into the
neck: it is situated on the inner side 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 vertebrae.
The Longissim.us Dorsi, the inner and larger portion of the Erector spinae,
arises, with the Sacro-lumbalis, from the common origin already mentioned. In
the lumbar region, where it is as yet blended with the Sacro-lumbalis, some of
the fibres are attached to the posterior surface of the transverse processes of the
lumbar vertebrae their whole length, to the tubercles at the back of the articular
OF THE BACK. 211
processes, and to the layer of lumbar fascia connected with the apices of the
transverse processes. In the dorsal region, the Longissimus dorsi is inserted,
by long thin tendons, into the tips of the transverse processes of all the dorsal
vertebrae, and into from seven to eleven ribs between their tubercles and angles.
This muscle is continued upwards to the cranium and cervical portion of the
spine, by means of two additional fasciculi, the Transversalis colli, and Trachelo-
mastoid.
The Transversalis Colli, placed on the inner side of the Longissimus dorsi, arises,
by long thin tendons, from the summit of the transverse processes of the third,
fourth, fifth, and sixth dorsal vertebrae, and is inserted, by similar tendons, into
the posterior tubercles of the transverse processes of the five lower cervical.
The Trachelo-mastoid lies on the inner side of the preceding, between it and
the Complexus muscle. It arises, by four tendons, from the transverse processes
of the third, fourth, fifth, and sixth dorsal vertebrae, and by additional separate
tendons from 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 inser-
tion into the mastoid process.
The Spinalis Dorsi connects the spinous processes of the upper lumbar and
the dorsal vertebrae together by a series of muscular and tendinous slips, which
are 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 dorsal vertebrae : these, uniting,
form a small muscle, which is inserted, by separate tendons, into the spinous
processes of the dorsal vertebrae, the number varying from four to eight. It is
intimately united with the Semi-spinalis dorsi, which lies beneath it.
The Spinalis Cervicis is a small muscle, connecting together the spinous pro-
cesses of the cervical vertebrae, and analogous to the Spinalis dorsi in the dorsal
region. It varies considerably in its size, and in its extent of attachment to the
vertebrae, 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 and sixth cervical vertebrae, and occasionally
from the first and second dorsal, and is inserted into the spinous process of the
axis, and occasionally into the spinous process of the two vertebrae below it.
This muscle has been found absent in five cases out of twenty -four.
The Complexus is a broad thick muscle, situated at the upper and back part of
the neck, beneath the Splenius, and internal to the prolongations from the
Longissimus dorsi. It arises, by a series of tendons, about seven in number, from
the tips of the transverse processes of the upper three dorsal and seventh cervical,
and from the articular processes of the three cervical above this. The tendons
uniting form a broad muscle, which passes obliquely upwards and inwards, and
is inserted into the innermost depression between the two curved lines of the occi-
pital bone. This muscle, about its middle, is traversed by a transverse tendinous
intersection.
The Biventer 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 separate muscle, arising, by from two to four tendinous slips, from
the transverse processes of as many upper dorsal vertebrae, and is inserted, on
the inner side of the Complexus, into the superior curved line of the occipital bone.
Relations. By their superficial surface, with the Trapezius and Splenius. By
their deep surface, with the Semi-spinalis dorsi and Semi-spinalis colli and the
Recti and Obliqui. The Biventer cervicis is separated from its fellow of the*
opposite side by the ligamentum nuchas, and the Complexus from the Semi-
spinalis colli by the profunda cervicis artery, the princeps cervicis, a branch of
the occipital, and by the posterior cervical plexus of nerves.
2T8 MUSCLES AND FASCIJS.
Nerves. The Erector spinas and its subdivisions in the dorsal region are sup-
plied by the external posterior branches of the lumbar and dorsal nerves ; the
Cervicalis ascendens, Transversalis colli, Trachelo-mastoid, and Spinalis cervicis,
by the external posterior branches of the cervical nerves ; the Complexus, by the
internal posterior branches of the cervical nerves, the suboccipital and great
occipital.
Fifth Layer.
Semi-spinalis Dorsi. Extensor Coccygis.
Semi-spinalis Colli. Inter-transversales.
Multifidus Spinas. Rectus Capitis Posticus Major.
Rotatores Spinas. Rectus Capitis Posticus Minor.
Supra-spinales. Obliquus Superior.
Inter-spinales. Obliquus Inferior.
Dissection. The muscles of the preceding layer must be removed by dividing and turning
aside the Complexus; then detach the Spinalis and Longissimus dorsi from their attachments,
and divide the Erector spinae 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.
The Semi-spinales muscles connect the transverse and articular processes to the
spinous processes of the vertebras, extending from the lower part of the dorsal
region to the upper part of the cervical.
The semi-spirialis dorsi consists of a thin, narrow, fleshy fasciculus, interposed
between tendons of considerable length. It arises by a series of small tendons
from the transverse processes of the lower dorsal vertebras, 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 dorsal and lower two cervical vertebras.
The semi-spinalis colli, thicker than the preceding, arises by a series of tendinous
and fleshy points from the transverse processes of the upper four dorsal vertebras,
and from the articular processes of the cervical vertebras (lower four) ; and is
inserted into the spinous processes of four cervical vertebras, from the axis to the
fifth cervical. The fasciculus connected with the axis is the largest, and chiefly
muscular in structure.
Relations. By their superficial surface, from below upwards, with the Longis-
simus dorsi, Spinalis dorsi, Splenius, Complexus, the profunda cervicis and prin-
ceps cervicis arteries, and the posterior cervical plexus of nerves. By their deep
surface, with the Multifidus spinas.
The Multifidus Spinse consists of a number of fleshy and tendinous fasciculi,
which fill up the groove on either side of the spinous processes of the vertebras,
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 aponeurosis
of origin of the Erector spinas. In the iliac region, they arise from the inner
surface of the posterior superior spine, and posterior sacro-iliac ligaments. In
the lumbar and cervical regions, they arise from the articular processes ; and in
the dorsal region, from the transverse processes. Each fasciculus, ascending
obliquely upwards and inwards, is inserted into the lamina and whole length of
the spinous process of the vertebra 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 vertebras.
Relations. By its superficial surface, with the Longissimus dorsi, Spinalis dorsi,
Semi-spinalis dorsi, and Semi-spinalis colli. By its deep surface, with the laminas
and spinous processes of the vertebras, and with the Rotatores spinas in the dorsal
region.
The Rotatores Spinse are found only in the dorsal region of the spine, beneath
the Multifidus spinas ; they are eleven in number on each side. Each muscle,
OF THE BACK. 279
which is small and somewhat quadrilateral in form, 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
inwards as the root of the spinous process. The first is found between the first
and second dorsal ; 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 Supra-spinales consist of a series of fleshy bands, which lie on the spinous
processes in the cervical region of the spine.
The Inter-spinales are short muscular fasciculi, placed in pairs between the
spinous processes of the contiguous vertebras.
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 dorsal. They are small narrow bundles, attached, above
and below, to the apices of the spinous processes.
In the dorsal region, they are found between the first and second vertebras, 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 vertebras. There is also occasionally one in the inter-
spinous space, between the last dorsal and first lumbar, and between the fifth
lumbar and the sacrum.
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 downwards to be inserted into the lower part of
the coccyx. It is a rudiment of the Extensor muscle of the caudal vertebras
present in some animals.
The Inter-transversaks are small muscles placed between the transverse pro-
cesses of the vertebras.
In the cervical region, they are most developed, consisting of two rounded
muscular and tendinous fasciculi, which pass between the anterior and posterior
tubercles of the transverse processes of two contiguous vertebras, being separated
from one another by the anterior branch of a cervical nerve, which lies in the
groove between them, and by the vertebral artery and vein. In this region, there
are seven pairs of these muscles, the first being between the atlas and axis, and
the last between the seventh cervical and first dorsal vertebra.
In the dorsal region, they are least developed, consisting chiefly of rounded
tendinous cords in the inter-transverse spaces of the upper dorsal vertebras ; but
between the transverse processes of the lower three dorsal vertebras and the first
lumbar, they are muscular in structure.
In the lumbar region, they are four in number, and consist of a single muscular
layer, which occupies the entire interspace between the transverse processes of
the lowest lumbar vertebras, whilst those between the transverse processes of the
upper lumbar are not attached to more than half the breadth of the process.
The Rectus Capitis Posticus Major, the larger of the two Recti, 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
ascend upwards and outwards, 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 the posterior arch of the
atlas, the posterior occipito-atloid ligament, and part of the occipital bone.
The Rectus Capitis Posticus Minor, the smallest 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, becoming broader as it ascends, is inserted
280 MUSCLES AND FASCIAE.
into the rough surface beneath the inferior curved line, nearly as far as the fora-
men magnum, nearer to the middle line than the preceding.
Relations. By its superficial surface, with the Complexus. By its deep surface,
with the posterior occipito-atloid ligament.
The Obliquus Inferior, the largest of the two oblique muscles, arises from the
apex of the spinous process of the axis, and passes almost horizontally outwards,
to be inserted into the apex of the transverse process of the atlas.
Relations. By its superficial surface, with the Complexus, and is crossed by the
posterior branch of the second cervical nerve. By its deep surface, with the ver-
tebral artery, and posterior occipito-atloid ligament.
The Obliquus Superior, narrow below, wide and expanded above, arises by ten-
dinous fibres from the upper part of the transverse process of the atlas, joining
with the insertion of the preceding, and, passing obliquely upwards and inwards,
is inserted into the occipital bone, between the two curved lines, external to the
Complexus. Between the two oblique muscles and the Rectus posticus major, a
triangular interval exists, in which are seen the vertebral artery, and the posterior
branch of the suboccipital nerve.
Relations. By its superficial surface, with the Complexus and Trachelo-mastoid.
By its deep surface, with the posterior occipito-atloid ligament.
Nerves. The Semi-spinalis dorsi and Rotatores spina? are supplied by the
internal posterior branches of the dorsal nerves. The Semi-spinalis colli, Supra-
spinales, and Inter-spinales, by the internal posterior branches of the cervical
nerves. The Inter-transversales, by the internal posterior branches of the cervical,
dorsal, and lumbar nerves. And the Multifidus spinas, by the same, with the
addition of the internal posterior branches of the sacral nerves. The Recti and
Obliqui muscles are all supplied by the suboccipital and great occipital nerves.
Actions. The Erector spina?, comprising the Sacro-lumbalis, with its accessory
muscles, the Longissimus dorsi and Spinalis dorsi, serves, as its name implies, to
maintain the spine in the erect posture ; it also serves to bend the trunk backwards,
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 development, as in pregnant women or in
abdominal dropsy ; the peculiar gait under such circumstances depending upon
the spine being drawn backwards, by the counterbalancing action of the Erector
spina? muscles. The continuation of these muscles upwards to the neck and head
steady and preserve the upright position of these several parts. If the Sacro-
lumbalis and Longissimus dorsi of one side act, they serve to draw down the
chest and spine to the corresponding side. The Musculus accessorius, taking its
fixed point from the cervical vertebra?, elevates those ribs to which it is attached.
The Multifidus spina? acts successively upon the different segments of the spine ;
thus, the lateral parts of the sacrum furnish 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 dorsal 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 with-
out the fatigue that would necessarily have existed had this movement been
accomplished by the action of a single muscle. The Multifidus spina?, 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, the analogues of the Multifidus spina? in the neck, draw the head
directly backwards ; 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 Rectus capitis posticus minor
and the Superior oblique draw the head backwards ; and the latter, from the
obliquity in the direction of its fibres, may turn the face to the opposite side.
The Rectus capitis posticus major and the Obliquus inferior rotate the atlas, and,
with it, the cranium round the odontoid process, and turn the face to the same side.
OF THE ABDOMEN.
281
Muscles of the Abdomen.
The muscles in this region are the
Obliquus Externus.
Obliquus Internus.
Transversalis.
Eectus.
Pyramidalis.
Quadratus Lumborum.
Fie. 162. — Dissection of Abdomen.
Dissection (fig. 162). To dissect the abdominal muscles, a vertical incision should be made
from the ensiform cartilage to the pubes ; a second
oblique incision should extend from the umbilicus
upwards and outwards 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, should pass transversely
outwards to the anterior superior iliac spine, and
along the crest of the ilium as far as its posterior
third. The three flaps included between these
incisions should then be reflected from within out-
wards, in the line of direction of the muscular
fibres. If necessary, the abdominal muscles may
be made tense by inflating the peritoneal cavity
through the umbilicus.
The External Oblique Muscle (fig. 163),
so called from the direction of its fibres,
is situated on the side and fore part of
the abdomen ; being the largest and the
most superficial of the three flat muscles
in this region. It is broad, thin, irregu-
larly quadrilateral in form, its muscular
portion occupying the side, its aponeurosis
the anterior wall of that cavity. It arises,
by eight fleshy digitations, from the ex-
ternal surface and lower borders of the
eight inferior ribs; these digitations are
arranged in an oblique line running downwards and backwards, the upper ones
being attached close to the cartilages of the corresponding ribs, the lowest to the
apex oFIhe 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 downwards, and are received between corresponding processes of the Ser-
ratus magnus ; the three lower ones diminish in size from above downwards,
receiving between them corresponding processes from the Latissimus dorsi.
From these attachments, the fleshy fibres proceed in various directions. Those
from the lowest ribs pass nearly vertically downwards, to be inserted into the
anterior half of the outer lip of the crest of the ilium ; the middle and upper
fibres, directed downwards and forwards, terminate in tendinous fibres, which
spread out into a broad aponeurosis. This aponeurosis, 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 aggregated together, and extend obliquely across from
the anterior superior spine of the ilium to the spine of the os pubis and the pec-
tineal line. In the median line, it interlaces with the aponeurosis of the opposite
muscle, forming the linea alba, and 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 inwards,
and continuous below with the fascia lata; it is called PouparCs ligament. The
portion which is reflected from Poupart's ligament backwards and inwards into the
pectineal line is called Oimhernais ligament. From the point of attachment of
282
MUSCLES AND FASCIAE.
the latter to the pectineal line, a few fibres pass upwards and inwards beneath the
inner pillar of the ring, to the linea alba. They diverge as they ascend, and form
a thin, triangular, fibrous band, which is called the triangular ligament.
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 sepa-
ration of the fibres of the aponeurosis in this situation ; it serves for the trans-
mission of the spermatic cord in the male, and the round ligament in the female.
Fig. 163.— The External Oblique Muscle.
£ if. Abdominal Bitty-
Cimbcrnal's Lin^~,
This opening is directed obliquely upwards and outwards, and 'corresponds with
the course of the fibres of the aponeurosis. It is bounded, below, by the crest of
the os pubis ; above, by some curved fibres, which pass across the aponeurosis at
the upper angle of the ring, so as to increase its strength ; and, on either side, by
the margins of the aponeurosis, which are called the pillars of the ring. Of
these, the external, which is, at the same time, inferior, from the obliquity of its
direction, is inserted into the spine of the os pubis. The internal or superior
OF THE ABDOMEN.
283
pillar, being attached to the front of the symphysis pubis, interlaces with the cor-
responding fibres of the opposite muscle, that of the right being superficial. To
the margins of the pillars of the external abdominal ring is attached an exceedingly
thin and delicate fascia, which is prolonged down over the outer surface of the
cord and testis. This has received the name of intercolumnar fascia, from its
attachment to the pillars of the ring. It is also called the external spermatic fascia,
from being the most external of the fascise which cover the spermatic cord.
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
ligament in the female. Its posterior border is occasionally overlapped by the
Latissimus dorsi ; sometimes an interval exists between the two muscles, in which
is seen a portion of the Internal oblique.
Dissection. The External oblique should now be detached by dividing it across, just in front
of its attachment to the ribs, as far as its posterior border, and by separating it below from the
crest of the ilium as far as the spine ; the muscle should then be carefully separated from the
Internal oblique, which lies beneath, and turned towards the opposite side.
The Internal Oblique Muscle (fig. 164), thinner and smaller than the preceding,
Fig. 164. — The Internal Oblique Muscle.
Conjoined Tendon
CREMASTER
beneath which it lies, is of an irregularly quadrilateral form, and situated at the
side and fore part of the abdomen. It arises, by fleshy fibres, from the outer half
284 MUSCLES AND FASCIAE.
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 lumbar
fascia. From this origin, the fibres diverge in different directions. Those from
Poupart's ligament, few in number and paler in color than the rest, arch down-
wards and inwards across the spermatic cord, to be inserted, conjointly with those
of the Transversalis, into the crest of the os pubis and pectineal line, to the extent
of half an inch, forming the conjoined tendon of the Internal oblique and Trans-
versalis; those from the anterior superior iliac spine are horizontal in their
direction, whilst those which arise from the fore part of the crest of the ilium
pass obliquely upwards and inwards, and terminate in an aponeurosis, which is
continued forwards to the linea alba. The most posterior fibres ascend almost
vertically upwards, to be inserted into the lower borders of the cartilages of the
four lower ribs, being continuous with the Internal intercostal muscles.
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 abdo-
minal ring, serving to protect what would otherwise be a weak point in the
abdomen. Sometimes this tendon is insufficient to resist the pressure from within,
and is carried forward in front of the protrusion through the external ring, form-
ing one of the coverings of direct inguinal herjiia.
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 pubes. At the
outer margin of the Pectus muscle, this aponeurosis, for the upper three-fourtli3
of its extent divides into two lamella?, which pass, one in front and the other
behind it, inclosing it in a kind of sheath, and reuniting on its inner border at
the linea alba : the anterior layer is blended with the aponeurosis of the External
oblique muscle, the posterior layer writh that of the Transversalis. Along the
lower fourth, the aponeurosis passes altogether in front of the Pectus without
any separation.
Relations. By its external surface, with the External oblique, Latissimus dorsi,
spermatic cord, and external ring. By its internal surface, withr the Transversalis
muscle, fascia transversalis, internal ring, and spermatic cord. Its lower border
forms the upper boundary of the spermatic canal.
Dissection. The Internal oblique should now be detached in order to expose the Transver-
salis beneath. This may be effected by dividing the muscle, above, at its attachment to the
ribs ; below, at its connection with Poupart's ligament and the crest of the ilium, and behind, by
a vertical incision extending from the last rib to the crest of the ilium. The muscle should pre-
viously 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 direc-
tion of the fibres of the latter muscle, will afford a clear guide to their separation ; along the
crest of the ilium the circumflex iliac vessels are interposed between them, and form an im-
portant guide in separating them. The muscle should then be thrown forwards towards the linea
alba.
The Transversalis muscle (fig. 165), 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, its anterior two-thirds, from
the inner surface of the cartilages of the six lower ribs, interdigitating with the
Diaphragm, and by a broad aponeurosis from the spinous and transverse processes
of the lumbar vertebrae. The lower fibres curve downwards, and are inserted,
together with those of the Internal oblique, into the crest of the os pubis and
pectineal line, forming what was before mentioned as the conjoined tendon of these
muscles. Throughout the rest of its extent the fibres pass horizontally inwards,
and near the outer margin of the Pectus terminate in an aponeurosis, which 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.
Relations. By its external surface, writh the Internal obliq le, the inner surface
OF THE ABDOMEN.
285
of the lower ribs, and Internal intercostal muscles. Its inner surface is lined by
the fascia transversalis, which separates it from the peritoneum. Its lower border
forms the upper boundary of the spermatic canal.
Lumbar Fascia (fig. 166). The vertebral aponeurosis of the Transversalis divides
into three layers, an anterior, very thin, which is attached to the front part of the
Fig. 165. — The Transversalis, Rectus, and Pyranridalis Muscles.
Tint
apices of the transverse processes of the lumbar vertebra, and, above, to the lower
margin of the last rib, forming the ligamentum arcuatum externum ; a middle
layer, much stronger, which is attached to the apices of the transverse processes ;
and a posterior layer, attached to the apices of the spinous processes. Between
the anterior and middle layers is situated the Quadratus lumborum, between the
middle and posterior the Erector spinae. The posterior lamella of this aponeurosis
receives the attachment of the Internal oblique ; it is also blended with the apo-
neurosis of the Serratus posticus inferior and with that of the Latissimus dorsi,
forming the lumbar fascia.
286
MUSCLES AND FASCIAE.
Dissection. To expose the Eectus muscle, its sheath should be opened by a vertical in-
cision extending from the margin of the thorax to the pubes, the two portions should then be
reflected from the surface of the muscle, which is easily effected, excepting at the lineae trans-
versa?, where so close an adhesion exists, that the greatest care is requisite in separating them.
The outer edge of the muscle should now be raised, when the posterior layer of the sheath will
be seen. By dividing the muscle in the centre, and turning its lower part downwards, the point
where the posterior wall of the sheath terminates in a thin curved margin will be seen.
The Rectus Abdominis 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 above than below, and arises by two
tendons, the external or larger being attached to the crest of the os pubis ; the
internal or smaller portion, interlacing with its fellow of the opposite side, and being
connected with the ligaments covering the symphysis pubis. The fibres ascend
vertically upwards, and the muscle, becoming broader and thinner at its upper
part, is inserted by three portions of unequal size into the cartilages of the fifth,
sixth, and seventh ribs. Some fibres are occasionally connected with the costo-
xiphoid ligaments, and side of the ensiform cartilage.
i
Fig. 166. — A Transverse Section of the Abdomen in the Lumbar Region.
The Eectus muscle is traversed by a series of tendinous intersections, which
vary from two to five in number, and have received the name lineae transversse.
One of these is usually situated opposite the umbilicus, and two above that point ;
of the latter, one corresponds to the ensiform cartilage, and the other to the interval
between the ensiform cartilage and the umbilicus. There is occasionally one below
the umbilicus. These intersections pass transversely or obliquely across the muscle
in a zigzag course ; they rarely extend completely through its substance, sometimes
pass only half way across it, and are intimately adherent to the sheath in which the
muscle is inclosed.
The Eectus is inclosed in a sheath (fig. 166) formed by the aponeuroses of the
Oblique and Transversalis muscles, which are arranged in the following manner:
When the aponeurosis of the Internal oblique arrives at the margin of the Eectus,
it divides into two lamellae, one of which passes in front of the Eectus, blending
with the aponeurosis of the External oblique, the other behind it, blending with
the aponeurosis of the Transversalis ; and these, joining again at its inner border,
are inserted into the linea alba. This arrangement of the fasciae 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 concavity of
which looks downwards towards the pubes ; the aponeuroses of all three muscles
passing in front of the Eectus without any separation. The Eectus muscle, in
OF THE ABDOMEN. 287
the situation where its sheath is deficient, is separated from the peritoneum by the
transversalis fascia.
The Pyramidalis is a small muscle, triangular in form, 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 upwards,
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 proportionally increased in size. Occasionally it has
been found double on one side ; at times the muscles of the two sides are of unequal
size. Sometimes its length ex«eeds that stated above.
The Quadratics Lumborum is situated in the lumbar region, is irregularly
quadrilateral in shape, broader below than above, and consists of two portions.
One portion 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, about half its length, and, by four small
tendons, into the apices of the transverse processes of the third, fourth, and fifth
lumbar vertebrae. The other portion of the muscle, situated in front of the pre-
ceding, arises from the upper borders of the transverse processes of the third,
fourth, and fifth lumbar vertebrae 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 vertebral aponeurosis of the Transversalis.
Nerves.' The abdominal muscles are supplied by the lower intercostal, ilio-
hypogastric, and ilio-inguinal nerves. The Quadratus lumborum receives filaments
from the anterior branches of the lumbar nerves.
In the description of the abdominal muscles, mention has frequently been made
of the linea alba, lineae semilunares, lineae transversae ; when the dissection of
these muscles is completed, these structures should be examined.
The linea alba is a tendinous raphe or cord, seen along the middle line of the
abdomen, extending from the ensiform cartilage to the pubes. It is placed
between the inner borders of the Recti muscles, and formed by the blending of
the aponeuroses of the Oblique and Transversalis 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 after great distension 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, which in the foetus transmits the umbilical
vessels, but in the adult is obliterated, the cicatrix being stronger than the neigh-
boring parts ; hence the occurrence of umbilical hernia in the adult above the
umbilicus, whilst in the foetus it occurs at the umbilicus. The linea alba is in
relation, in front, with the integument to which it is adherent, especially at the
umbilicus ; behind, it is separated from the peritoneum by the transversalis fascia ;
and below, by the urachus, and the bladder, when that organ is distended.
The lineae 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 eighth rib to the pubes, and is formed by the
aponeurosis of the Internal oblique at its point of division to inclose the Rectus.
The lineae transversa are three or four narrow transverse lines which intersect
the Rectus muscle, as already mentioned, and connect the lineae semilunares with
the linea alba.
Actiom. The abdominal muscles perform a threefold action.
1. When the pelvis and thorax are fixed, they can 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 ingesta from the stomach in vomiting.
288 MUSCLES AND FASCIA.
2. If the spine is fixed, these muscles can compress the lower part of the thorax,
materially assisting in expiration. If the spine is not fixed, the thorax is bent
directly forward, if the muscles of both sides act, or to either side if they act
alternately, rotation of the trunk at the same time taking place to the opposite
side.
3. If the thorax is fixed, these muscles, acting together, draw the pelvis upwards,
as in climbing ; or, acting singly, the pelvis is drawn upwards, and the vertebral
column rotated to one or the other side. The Eecti 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 Pyramidales are
tensors of the linea alba.
Muscles and Fascia of the Thoeax.
The muscles exclusively connected with the bones in this region are few in
number. They are the
Intercostales Externi. Infra-costales.
Intercostales Interni. Triangularis Sterni.
Levatores Costarum.
Intercostal Fascise. A thin but firm layer of fascia covers the outer surface of
the External intercostal and the inner surface of the Internal intercostal muscles ;
and a third layer, more delicate, is interposed between the two planes of muscular
fibres. These are the intercostal fascise ; 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 are two thin planes of muscular and tendinous struc-
ture, 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 names
" external" and " internal," from the position they bear to one another.
The External Intercostals are eleven in number on each side, being attached
to the adjacent margins of each pair of ribs, and extending from the tubercles of
the ribs, behind, to the commencement of the cartilages of the ribs, in front,
where they terminate in a thin membranous aponeurosis, which is continued for-
wards to the sternum. They arise from the outer lip of the groove on the lower
border of each rib, and are inserted into the upper border of the rib below.
In the two lowest spaces they extend to the end of the ribs. Their fibres are
directed obliquely downwards and forwards, in a similar direction with those of
the External oblique muscle. 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, Rhomboideus
major, Serratus posticus superior and inferior, Scalenus posticus, Sacro-lumbalis
and Longissimus dorsi, Cervicalis ascendens, Transversalis colli, Levatores costa-
rum, and the Obliquus externus abdominis. By their internal surface, with a thin
layer of fascia, which separates them from the intercostal vessels and nerve, the
Internal intercostal muscles, and, behind, from the pleura.
The Internal Intercostals, also eleven in number on each side, are placed on
the inner surface of the preceding, commencing anteriorly at the sternum, in the
interspaces between the cartilages of the true ribs, and from the anterior extremi-
ties of the cartilages of the false ribs; and extend backwards as far as the angles
of the ribs, where they are continued to the vertebral column by a thin aponeu-
rosis. They arise from the inner lip of the groove on the lower border of each
rib, as well as from the corresponding costal cartilage, and are inserted into the
upper border of the rib below. Their fibres are directed obliquely downwards
and backwards, decussating with the fibres of the preceding.
Relations. By their external surface, with the External intercostals, and the
OF THE THORAX. 28!)
intercostal vessels and nerves. By their internal surface, with the pleura costalis.
Triangularis sterni, and Diaphragm.
The Intercostal muscles consist of muscular and tendinous fibres, the latter
being longer and more numerous than the former ; hence these spaces present very
considerable strength, to which their crossing materially contributes.
The Infra-costales consist of muscular and aponeurotic fasciculi, which vary in
number and length ; they arise from the inner surface 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 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
part of the side of the sternum, from the inner surface of the ensiform cartilage,
and from the sternal ends of the costal cartilages of the three or four lower true
ribs. Its fibres diverge upwards and outwards, to be inserted by fleshy digitations
into the lower border and inner surfaces of the costal cartilages of the second,
third, fourth, and fifth 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, the costal cartilages,
the Internal intercostal muscles, and internal mammary vessels. Behind, with
the pleura, pericardium, and anterior mediastinum.
The Levatores Costarum, twelve in number on each side, are small tendinous
and fleshy bundles, which arise from the extremities of the transverse processes
of the dorsal vertebrae, and, passing obliquely downwards and outwards, are in-
serted into the upper rough surface of the rib below them, between the tubercle
and the angle. That for the first rib arises from the transverse process of the last
cervical vertebra, and that for the last from the eleventh dorsal. 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.
Actions. The Intercostals are the chief agents in the movement of the ribs in
ordinary respiration. The External intercostals raise the ribs, especially their fore
part, and so increase the capacity of the chest from before backwards ; at the same
time they evert their lower borders, and so enlarge the thoracic cavity trans-
versely. 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 fore
part of the chest these muscles assist the External intercostals in raising the car-
tilages. The Levatores Costarum assist the External intercostals in raising the
ribs. The Triangularis sterni draws down the costal cartilages ; it is therefore an
expiratory muscle.
Diaphragmatic Region-.
Diaphragm. (Fig. 167.)
The Diaphragm (&ta$pdoea, to separate two parts), is a thin musculo-fibrous sep-
tum, placed obliquely at the junction of the upper with the lower two-thirds of
the trunk, and separating 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, somewhat fan-shaded, the broad elliptical portion being horizon-
tal, the narrow part, which represents the handle, being vertical, and joined at right
angles with the former. It is from this circumstance that some anatomists describe
it as consisting of two portions, the upper or greater muscle of the Diaphragm,
and the lower or lesser muscle. It arises from the whole of the internal circum-
19
290
MUSCLES AND FASCIAE.
ference of the thorax, being attached, in front, by fleshy fibres to the ensiform car-
tilage ; on each side, to the inner surface of the cartilages and bony portions of
the six or seven interior ribs, interdigitating with the Transversalis ; and behind,
to two aponeurotic arches, named the ligamentum arcuatum externum and liga-
mentum arcuatum internum ; and to the lumbar vertebra;. The fibres from these
sources vary in length ; those arising from the ensiform appendix are very short
and occasionally aponeurotic ; but those from the ligamenta arcuata, and more
especially those from the ribs at the side of the chest, are the longest, 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
Fig. 167.— The Diaphragm. Under Surface.
of the Diaphragm are deficient, the interval being filled by areolar tissue, covered
on the thoracic side by the pleuras ; on the abdominal, by the peritoneum. This
is, consequently, a weak point, and a portion of the contents of the abdomen
may protrude into the chest, forming phrenic or diaphragmatic hernia, or a
collection of pus in the mediastinum may descend through it, so as to point at the
epigastrium.
The ligamentum arcuatum internum 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, and occasionally the second,
lumbar vertebra, being continuous with the outer side of the tendon of the cor-
responding crus; and, by the other end, to the front of the transverse process of
the second lumbar vertebra.
DIAPHRAGMATIC REGION. 291
The Ugamentum arcuatum externum is the thickened upper margin of the
anterior lamella of the transversalis fascia ; it arches across the upper part of the
Quadratus lumborum, being attached, by one extremity, to the front of the trans-
verse process of the second lumbar vertebra ; and, by the other, to the apex and
lower margin of the last rib.
To the spine, the Diaphragm is connected by two crura, which are situated on
the bodies of the lumbar vertebrae, one on each side of the aorta. The crura, at
their origin, are tendinous in structure ; the right crus, larger and longer than the
left, arising from the anterior surface of the bodies and intervertebral substances
of the second, third, and fourth lumbar vertebras ; the left, from the second and
third ; both blending with the anterior common ligament of the spine. A tendi*
nous arch is thrown across the front of the vertebral column, from the tendon of
one crus to that of the other, beneath which pass the aorta, vena azygos major,
and thoracic duct. The tendons terminate in two large fleshy bellies, which, with
the tendinous portions above alluded to, are called the crura or pillars of the dia-
phragm. The outer fasciculi of the two crura are directed upwards and outwards
to the central tendon ; but the inner fasciculi decussate in front of the aorta, and
then diverge, so as to surround the oesophagus before ending in the central
tendon. The most anterior and larger of these fasciculi is formed by the right
crus.
The Central or Cordiform Tendon of the Diaphragm is a thin tendinous apo-
neurosis, situated at the centre of the vault of this muscle, immediately beneath
the pericardium, with which its circumference is blended. It is shaped somewhat
like a trefoil leaf, consisting of three divisions or leaflets, separated from one
another by slight indentations. The right leaflet is the largest ; the middle one,
directed towards the ensiform cartilage, the next in size ; and the left, the smallest.
In structure, it 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 additional strength to the tendon.
The Openings connected with the Diaphragm are three large and several
smaller apertures. The former are the aortic, oesophageal, and the opening for the
vena cava.
The aortic opening is the lowest and the most posterior of the three large aper-
tures connected with this muscle. It is situated in 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 vertebras, from the crus on one side to that
on the other, and transmits the aorta, vena azygos major, thoracic duct, and occa-
sionally the left sympathetic nerve.
The (Esophageal opening, elliptical in form, muscular in structure, and formed
by the two crura, is placed above, and, at the same time, anterior to, and a little to
the left of, the preceding. It transmits the oesophagus and pneumogastric nerves.
The anterior margin of this aperture is occasionally tendinous, being formed by
the margin of the central tendon.
The opening for the vena cava is the highest ; it is quadrilateral in form, ten-
dinous in structure, and placed at the junction of the right and middle leaflets of
the central tendon, its margins being bounded by four bundles of tendinous fibres,
which meet at right angles.
The right crus transmits the sympathetic and the greater and lesser splanchnic
nerves of the right side ; the left crus, the greater and lesser splanchnic nerves of
the left side, and the vena azygos minor.
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 serous layer
of the pericardium, which covers the middle portion of the tendinous centre.
The serous membrane covering its under surface is a portion of the general peri-
toneal membrane of the abdominal cavity.
292 MUSCLES AND FASCIAE.
The Diaphragm is arched, being convex towards the chest, and concave to the
abdomen. The right portion forms a complete arch from before backwards, 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
backwards 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. The central portion, which sup-
ports the heart, is higher, in front at the sternum, and behind at the vertebrae,
than the lateral portions; but deeper, this is reversed.
The height of the Diaphragm is constantly varying during respiration, being
carried upwards or downwards from the average level ; its height also varies
according to the degree of distension 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 the breadth of from one to
two ribs 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 towards the tenth rib.
Nerves. The Diaphragm is supplied by the phrenic nerves.
Actions. The action of the Diaphragm modifies considerably the size of the
chest, and the position of the thoracic and abdominal viscera. During a forced
inspiration, the cavity of the thorax is enlarged in the vertical direction from
two to three inches, partly from the ascent of the walls of the chest, partly from
the descent of the Diaphragm. The chest, consequently, encroaches upon the
abdomen ; the lungs are expanded, and lowered, in relation with the ribs, nearly
two inches; the heart being drawn down about an inch and a half, the descent
of the latter organ taking place indirectly through the medium of its connec-
tion with the lungs, as well as directly by means of the central tendon to which
the pericardium is attached. The abdominal viscera are also pushed down (the
liver, to the extent of nearly three inches), so that these organs are no longer
protected by the ribs. During expiration, when the Diaphragm is passive, it is
pushed up by the action of the abdominal muscles ; the cavity of the abdomen,
with the organs contained in it, encroaches upon the chest, by which the lungs
and heart are compressed upwards, and the vertical diameter of the thoracic cavity
diminished. The Diaphragm is passive when raised or lowered by the abdominal
organs, independently of respiration, in proportion as they are large or small, full
or empty ; hence the oppression felt in the chest after a full meal, or from flatulent
distension of the stomach and intestines.
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 fasces, or of
the foetus from the womb, a deep inspiration takes place.'
Muscles of the FEKiNEUir.
These muscles are described with the anatomy of the Perineum (p. 778).
' For a detailed description of the general relations of the Diaphragm, and its action, refer to
X)r. Sibson's " Medical Anatomy."
UPPER EXTREMITY.
293
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.
Anterior Thoracic Region.
Pectoralis major.
Pectoral is minor.
Subclavius.
Lateral Tlioracic Region.
Serratus magnus.
Acromial Region.
Deltoid.
Anterior Scapular Region.
Subscapulars.
Posterior Scapular Region.
Supra-spinatus.
Infra-spinatus.
Teres minor.
Teres major.
Anterior Humeral Region.
Coraco-brachialis.
Biceps.
Brachialis anticus.
Posterior Humeral Region.
Triceps.
Subanconeus.
Anterior Brachial Region.
1. Superficial Layer.
Pronator radii teres.
Flexor carpi radialis.
Palmaris longus.
Flexor carpi ulnaris.
Flexor sublimis digitorum.
2. Deep Layer.
Flexor profundus digitorum.
Flexor longus pollicis.
Pronator quadratus.
Radial Region.
Supinator longus.
Extensor carpi radialis longior.
Extensor carpi radialis brevior.
Posterior Brachial Region.
1. Superficial Layer.
Extensor communis digitorum.
Extensor minimi digiti.
Extensor carpi ulnaris.
Anconeus.
2. Deep Layer.
Supinator brevis.
Extensor ossis metacarpi pollicis.
Extensor primi internodii pollicis.
Extensor secundi internodii pollicis.
Extensor indicis.
Muscles of the Hand.
Radial Region.
Abductor pollicis.
Flexor ossis metacarpi pollicis (opponens).
Flexor brevis pollicis.
Adductor pollicis.
Ulnar Region.
Palmaris brevis.
Abductor minimi digiti.
Flexor brevis minimi digiti.
Flexor ossis metacarpi minimi digiti.
Palmar Region.
Lumbricales.
Interossei palmares.
Interossei dorsales.
Dissection of Pectoral Region and Axilla (fig. 168). The arm being drawn away from the
side nearly at right angles with the trunk, and rotated outwards, a vertical incision should be
made through the integument in the median line of the chest, from the upper to the lower part
of the sternum ; a second incision should be carried along the lower border of the Pectoral mus-
cle, from the ensiform cartilage to the outer 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 down-
wards, along the interspace between the Pectoral and Deltoid muscles, as low as the fold of the
arm-pit. The flap of integument may then 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 arm-pit, and the integument reflected outwards, the axillary space
will be more completely exposed.
294
MUSCLES AND FASCIAE.
3.Dissecti0Ti erf
SHOULDER & ARM
Fasciae of the Thorax.
The superficial fascia of the thoracic region is a loose cellulo-fibrous layer, con-
tinuous with the superficial fascia of the neck and upper extremity above, and
of the abdomen below. Opposite the mamma, it subdivides into two layers, one
_ , „„ L, _ _ . of which passes in front, the other
behind this gland; and from both
of these layers numerous septa pass
into its substance, supporting its
various lobes; from the anterior
layer, fibrous processes pass for-
ward to the integument and nipple,
inclosing in their areolae masses of
fat. These processes were called,
by Sir A. Cooper, the ligamenta
suspensoria, from the support they
afford to the gland in this situation.
On removing the superficial fascia,
the deep fascia of the thoracic region
is exposed ; it is a thin aponeurotic
lamina, covering 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 clavi-
cle; it is very thin over the upper
part of the muscle, somewhat thicker
in the interval between the Pecto-
ralis major and Latissimus dorsi,
where it closes in the axillary space,
and divides at the margin of the
latter 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 dorsal vertebrae, to which they are attached.
At the lower part of the thoracic region, this fascia is well developed, and is con-
tinuous with the fibrous sheath of the Eecti muscles.
/. Jilssretiou of
2.BCfiDofrZLB0W
FORE-ARM
&, PALM i?/" HAND
Anterior Thoracic Eegion.
Pectoralis Major.
Pectoralis Minor.
Subclavius.
The Pectoralis Major (fig. 169) is a broad, thick, triangular muscle, situated at
the upper and fore part of the chest, in front of the axilla. It arises from the
sternal half of the clavicle, its anterior surface, and from one half the breadth of
the front of the sternum, as low down as the attachment of the cartilage of the
sixth or seventh rib ; its origin consisting of aponeurotic fibres, which intersect
those of the opposite muscle. It also arises from the cartilages of all the true
ribs, and from the aponeurosis of the External oblique muscle of the abdomen.
The fibres from this extensive origin converge towards its insertion, giving to the
muscle a radiated appearance. Those fibres which arise from the clavicle pass
obliquely doAvnwards and outwards, and are usually separated from the rest by a cel-
lular interval ; those from the lower part of the sternum and the cartilages of the lower
true ribs pass upwards and outwards, whilst the middle fibres pass horizontally.
As these three sets of fibres converge, they are so disposed that the upper overlap
ANTERIOR THORACIC REGION. 295
the middle, and the middle the lower portion, the fibres of the lower portion being
folded backwards upon themselves ; so that those fibres which are lowest in front,
become highest at their point of insertion. They all terminate in a flat tendon,
about two inches broad, which is inserted into the anterior bicipital ridge of the
humerus. This tendon consists of two laminae, placed one in front of the other,
and usually blended together below. The anterior, the thicker, receives the cla-
vicular and upper half of the sternal portion of the muscles; the posterior lamina
Fig. 109. — Muscles of the Chest and Front of the Arm. Superficial View.
I ilk
receiving the attachment of the lower half of the sternal portion. From this
arrangement it results, that the fibres of the upper and middle portions of the
muscle are inserted into the lower part of the bicipital ridge ; those of the lower
portion, into the upper part. The tendon, at its insertion, is connected with that
of the Deltoid ; it sends up an expansion over the bicipital groove to the head of
the humerus, another backwards, which lines the groove, and a third to the fascia
of the arm.
296 MUSCLES AND FASCIJE.
Relations. By its anterior surface, with the Platysma, the mammary gland, the
superficial fascia, and integument. By its posterior surface: its thoracic portion,
with the sternum, the ribs and costal cartilages, the Subclavius, Pectoralis minor,
Serratus magnus, and the Intercostals ; its axillary portion forms the anterior
wall of the axillary space, and covers the axillary vessels and nerves. Its upper
border lies parallel with the Deltoid, from which it is separated by the cephalic
vein and descending branch of the thoracico-acromialis 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 towards the
outer part of this space.
Peculiarities. In muscular subjects, the sternal origins of the two Pectoral muscles are
separated only by a narrow interval ; but this interval is enlarged where these muscles are ill-
developed. Very rarely, the whole of the sternal portion is deficient. Occasionally, one or two
additional muscular slips arise from the aponeurosis of the External oblique, and become united
to the lower margin of the Pectoralis major. A slender muscular slip is occasionally found
lying parallel with the outer margin of the sternum, overlapping the origin of the Pectoral
muscle. It is attached, by one end. to the upper part of the sternum, near the origin of the
Sterno-mastoid ; and, by the other, to the anterior wall of the sheath of the Rectus abdominis.
It has received the name "Rectus sternalis."
Dissection. The Pectoralis major should now be detached 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
outwards, and its tendon carefully examined. The Pectoralis minor is now exposed, and imme-
diately above it, in the interval between its upper border and the clavicle, is a strong fascia, the
costo-coracoid membrane.
The costo-coracoid membrane protects the axillary vessels and nerves, and is
very thick and dense externally, where it is attached to the coracoid process, and
is continuous with the fascia of the arm ; more internally, it is connected with the
lower border of the clavicle, as far as the inner extremity of the first rib : traced
downwards, it passes behind the Pectoralis minor, surrounding in a more or less
complete sheath, the axillary vessels and nerves ; and above, it sends a prolongation
behind the Subclavius, which is attached to the lower border of the clavicle, and
so incloses the muscle in a kind of sheath. The costo-coracoid membrane is
pierced by the cephalic vein, the acromial-thoracic artery and vein, superior
thoracic artery, and anterior thoracic nerve.
The Pectoralis minor (fig. 170) 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 upwards and outwards, and converge to form a flat
tendon, which is inserted into the anterior border of the coracoid process of the
scapula.
Relations. By its anterior surface, with the Pectoralis major, and the superior
thoracic vessels and nerves. By its posterior surface, with the ribs, Intercostal
muscles, Serratus magnus, the axillary space, and the axillary vessels and nerves.
Its upper border is separated from the clavicle by a triangular interval, broad
internally, narrow externally, bounded in front by the costo-coracoid membrane,
and internally by the ribs. In this space are seen the axillary vessels and nerves.
The costo-coracoid membrane should now be removed, when the Subclavius muscle will be seen.
The Subclavius (fig. 170) is a long, thin, spindle-shaped muscle, placed in the
interval between the clavicle and the first rib. It arises by a short, thick tendon,
from the cartilage of the first rib, in front of the rhomboid ligament ; the fleshy
fibres proceed obliquely outwards to be inserted into a deep groove on the under
surface of the middle third of the clavicle.
Relations. By its upper surface, with the clavicle. By its under surface, it is
separated from the first rib by the axillary vessels and nerves. Its anterior
ANTERIOR THORACIC REGION
29T
surface is separated from the Pectoralis major by a strong aponeurosis, which,
with the clavicle, forms an osteo-fibrous sheath in which the muscle is inclosed.
If the costal attachment of the Pectoralis minor is divided across, and the muscle reflected
outwards, 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 Subclavius, by a filament from the cord formed by the union of the fifth and
sixth cervical nerves.
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 ; and, if acting singly, it will draw the arm across the front of the chest.
Fig. 170. — Muscles of the Chest and Front of the Arm, with the boundaries
of the Axilla.
The Pectoralis minor depresses the point of the shoulder, drawing the scapula
downwards and inwards to the thorax. The Subclavius depresses the shoulder,
drawing the clavicle downwards and forwards. When the arms are fixed, all three
muscles act upon the ribs, drawing them upwards and expanding the chest, thus
becoming very important agents in forced inspiration. Asthmatic patients always
assume this attitude, fixing the shoulders, so that all these muscles may be brought
into action to assist in dilating the. cavity of the chest.
298 MUSCLES AND "PASCIJE.
Lateral Thoracic Eegiox.
Serratus Magnus.
The Serratus Magnus is a broad, thin, and irregularly quadrilateral muscle,
situated at the upper part and side of the chest. It arises by nine fleshy digita-
tions from the outer surface and upper border of the eight upper ribs (the second
rib having two), and from the aponeurosis covering the upper intercostal spaces,
and is inserted into the whole length of the inner margin of the posterior border
of the scapula. This muscle has been divided into three portions, a superior,
middle, and inferior, on account of the difference in the direction, and in the ex-
tent of attachment of each part. The upper portion, separated from the rest by a
cellular interval, is a narrow, but thick fasciculus, which arises by two digitations
from the first and second ribs, and from the aponeurotic arch between them ; its
fibres proceed upwards, outwards and backwards, to be inserted into the triangular
smooth surface on the inner side of the superior angle of the scapula. The middle
portion of the muscle arises by three digitations from the second, third and fourth
ribs, and forms a thin and broad muscular layer, which proceeds horizontally back-
wards, to be inserted into the posterior border of the scapula, between the superior
and inferior angles. The lower portion arises from the fifth, sixth, seventh and
eighth ribs, by four digitations, in the intervals between which are received cor-
responding processes of the External oblique ; the fibres pass upwards, outwards,
and backwards, to be inserted into the inner surface of the inferior angle of the
scapula, by an attachment partly muscular, partly tendinous.
Relations. This muscle is covered, in front, by the Pectoral muscles ; behind,
by the Subscapularis ; above, by the axillary vessels and nerves. Its deep surface
rests upon the ribs and Intercostal muscles.
Nerves. The Serratus magnus is supplied by the posterior thoracic nerve.
Actions. The Serratus magnus is the most important external inspiratory
muscle. When the shoulders are fixed, it elevates the ribs, and so dilates the
cavity of the chest, assisting the Pectoral and Subclavius muscles. This muscle,
especially its middle and lower segments, draws the base and inferior angle of the
scapula forwards, and so raises the point of the shoulder by causing a rotation of
the bone on the side of the chest ; assisting the Trapezius muscle in supporting
weights upon the shoulder, the thorax being at the same time fixed by preventing
the escape of the included air.
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, behind, the
Levator anguli scapulae, the Ilhomboidei, Trapezius, and Latissimus dorsi. These muscles should
be cleaned and traced to their respective insertions. An incision should then be made through
the integument, commencing at the outer third of the clavicle, and extending along the margin
of this bone, the acromion process, and spine of the scapula ; the integument should be dissected
from above downwards and outwards, when the fascia covering the Deltoid is exposed.
The superficial fascia of the upper extremity is a thin cellulo-fibrous lamina,
containing between its layers the superficial veins and lymphatics, and the cuta-
neous nerves. It is most distinct in front of the elbow, and contains between
its laminas in this situation the large superficial cutaneous veins and nerves ; in
the hand it is hardly demonstrable, the integument being closely adherent to the
deep fascia by dense fibrous bands. Small subcutaneous bursas are found in this
fascia, over the acromion, the olecranon, and the knuckles. The deep fascia of
the upper extremity comprises the aponeurosis of the shoulder, arm, and fore-
arm, the anterior and posterior annular ligaments of the carpus, and the palmar
fascia. These will be considered in the description of the muscles of these several
regions.
ACROMIAL AND SCAPULAR REGIONS. 2G9
Acromial Region.
Deltoid.
The deep fascia covering the Deltoid (deltoid aponeurosis) is a thick and strong
fibrous layer, which covers the outer surface of the muscle, and sends down nume-
rous prolongations between its fasciculi; it is continuous, internally, with the
fascia covering the great Pectoral muscle ; behind, with that covering the Infra-
spinatus and back of the arm ; above, it is attached to the clavicle, the acromion,
and spine of the scapula.
The Deltoid is a large, thick, triangular muscle, which forms the convexity of
the shoulder, and has received its name from its resemblance 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 whole length of
the lower border of the spine of the scapula. From this extensive origin, the
fibres converge towards their insertion, the middle passing vertically, the anterior
obliquely backwards, the posterior obliquely forwards ; they unite to form a thick
tendon, which is inserted into a rough prominence on the middle of the outer side
of the shaft of the humerus. This muscle is remarkably coarse in texture, and
intersected by three or four tendinous laminae ; these are attached, at intervals, to
the clavicle and acromion, extend into the substance of the muscle, and give origin
to a number of fleshy fibres. The largest of these laminae extends from the
summit of the acromion.
Relations. By its superficial surface, with the Platysma, supra-acromial nerves,
the superficial fascia, and integument. Its deep surface is separated from the
head of the humerus by a large sacculated synovial bursa, and covers the coracoid
process, coraco-acromial' ligament, Pectoralis minor, Coraco-brachialis, both heads
of the Biceps, tendon of the Pectoralis major, Teres minor, scapular and external
heads of the Triceps, the circumflex vessels and nerve, and the humerus. Its
anterior border is separated from the Pectoralis major by a cellular interspace,
which lodges the cephalic vein and descending branch of the acromial-thoracic
artery. Its posterior border rests on the Infra-spinatus and Triceps muscles.
Nerves. The Deltoid is supplied by the circumflex nerve.
Actions. The Deltoid raises the arm directly from the side, so as to bring it at
right angles with. the trunk. Its anterior fibres, assisted by the Pectoralis major,
draw the arm forwards ; and its posterior fibres, aided by the Teres major and
Latissimus dorsi, draw it backwards.
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 downwards;
the bursa will be seen on its under surface, as well as the circumflex vessels and nerves. The
insertion of the muscle should be carefully examined.
Anterior Scapular Region.
Subscapularis.
The subscapular aponeurosis is a thin membrane, attached to the entire circum-
ference of the subscapular fossa, and affording attachment by its inner surface to
some of the fibres of the Subscapularis muscle : when this is removed, the latter
is exposed.
The Subscapularis 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 inner side of the superior and inferior angles,
which afford attachment to the Serratus magnus. 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 muscle from the Teres major and
300 MUSCLES AND FASCI.E.
the long head of the Triceps. The fibres pass outwards, 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 capsular ligament of the shoulder-joint,
and glides over a large bursa, 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. •
Relations. By its anterior surface, with the Serratus magnus, Coraco-brachialis,
and Biceps, and the axillary vessels and nerves. By its posterior surface, with
the scapula, the subscapular vessels and nerves, and the capsular ligament of the
shoulder-joint. Its lower border is contiguous with the Teres major and Latissi-
mus dorsi.
Nerves. It is supplied by the subscapular nerves.
Actions. The Subscapularis rotates the head of the humerus inwards ; when
the arm is raised, it draws the humerus downwards. It is a powerful defence to
the front of the shoulder-joint, preventing displacement of the head of the bone
forwards.
Posterior Scapular Kegion-.
Supra-spinatus. Teres Minor.
Infra-spinatus. Teres Major.
Dissection. To expose these muscles, and to examine their mode of insertion into the hume-
rus, detach the Deltoid and Trapezius from their attachment to the spine of the scapula and acro-
mion 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, and, the fragments being removed, the tendons of the posterior Scapular mus-
cles 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 supraspinous aponeurosis is a thick and dense membranous layer, which
completes the osteo-fibrous case in which the Supra-spinatus muscle is contained ;
affording attachment, by its inner surface, to some of the fibres of this muscle.
It is thick internally, but thinner externally under the coraco-acromial ligament.
When this fascia is removed, the Supra-spinatus muscle is exposed.
The Supra-spinatus muscle occupies the whole of the supra-spinous fossa, arising
from its internal two-thirds, and from a strong fascia which covers its surface.
The muscular fibres converge to a tendon, which passes across the capsular liga-
ment of the shoulder-joint, to which it is intimately adherent, 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 supra-scapular vessels and nerve, and upper part of the shoulder-
joint.
The infra-spinous aponeurosis is a dense fibrous membrane, covering in the
Infra-spinatus muscle, and attached to the circumference of the infra-spinous fossa ;
it affords attachment, by its inner surface, to some fibres of this muscle, is con-
tinuous externally with the fascia of the arm, and gives off from its under surface
intermuscular septa, which separate the Infra-spinatus from the Teres minor, and
the latter from the Teres major.
The Infra-spinatus is a thick triangular muscle, which occupies the chief part
of the infra-spinous fossa, arising by fleshy fibres, from its internal two-thirds ;
and by tendinous fibres, from the ridges on its surface : it also arises from a strong
fascia which covers it externally, and separates it from the Teres major and Teres
minor. The fibres converge to a tendon, which glides over the concave border of
the spine of the scapula, and, passing across the capsular ligament of the shoulder-
joint, is inserted into the middle facet on the great tuberosity of the humerus.
SC4PTJLAR REGION.
Wl
The tendon of tins muscle is occasionally separated from the spine of the scapula
by a synovial bursa, which communicates with the synovial membrane of the
shoulder-joint.
Relations. By its posterior surface, with the Deltoid, the Trapezius, Latissimus
dorsi, and the iDtegument. By its anterior surface, with the scapula, from which
it is separated by the superior and dorsalis scapula? vessels, and with the capsular
ligament of the shoulder-joint. Its lower border is in contact with the Teres minor,
and occasionally united with it, and with the Teres major.
The Teres Minor is a narrow elongated muscle, which lies along the inferior
border of the scapula. It 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 Infra-spinatus, the other from
Fig. 171. — Muscles on the Dorsum of the Scapula and the Triceps.
the Teres major; its fibres pass obliquely upwards and outwards, 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 capsular ligament of the
shoulder -joint.
Relations. By its posterior surface, with the Deltoid, Latissimus dorsi, and in-
tegument. By its anterior surface, with the scapula, the dorsal branch of the
subscapular artery, the long head of the Triceps, and the shoulder-joint. By its
upper border with the Infra-spinatus. 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 broad and somewhat flattened muscle, which arises from
the dorsal aspect of the inferior angle of the scapula, and from the fibrous septa
302 MUSCLES AND FASCIA.
interposed between it and the Teres minor and Infra-spinatus ; the fibres are
directed upwards and outwards, and terminate in a flat tendon, about two inches
in length, which is inserted into the posterior 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.
Relations. By its posterior surface, with the integument, from which it is
separated, internally, by the Latissimus dorsi ; and externally, by the long head of
the Triceps. By its anterior surface, with the Subscapularis, Latissimus dorsi,
Coraco-brachialis, short head of the Bi<?eps, the axillary vessels, and brachial
plexus of nerves. Its upper border is at first in relation with the Teres minor,
from which it is afterwards separated by the long head of the Triceps. Its
lower border forms, in conjunction with the Latissimus dorsi, part of the posterior
boundary of the axilla.
Nerves. The Supra-spinati and Infra-spinati muscles are supplied by the supra-
scapular nerve ; the Teres minor, by the circumflex ; and the Teres major, by the
subscapular.
Actions. The Supra-spinatus assists the Deltoid in raising the arm from the
side ; its action must, however, be very feeble, from the very disadvantageous
manner in which the force is applied. The Infra-spinatus and Teres minor rotate
the head of the humerus outwards ; when the arm is raised, they assist in retaining
it in that position, and carrying it backwards. One of the most important uses
of these three muscles is the great protection they afford to the shoulder-joint, the
Supra-spinatus supporting it above, and preventing displacement of the head of
the humerus upwards, whilst the Infra-spinatus and Teres minor protect it behind,
and prevent dislocation backwards. The Teres major assists the Latissimus dorsi
in drawing the humerus downwards and backwards when previously raised, and
rotating it inwards ; when the arm is fixed, it may assist the Pectoral and Latis*
simus dorsi muscles in drawing the trunk forwards.
Anterior Humeral Region.
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 middle of the interval
between the folds of the axilla, 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.
The deep fascia of the arm, continuous with that covering the shoulder and
front of the great Pectoral muscle, is attached, above, to the clavicle, acromion,
and spine of the scapula ; it forms a thin, loose, membranous sheath investing the
muscles of the arm, sending down septa between them, and composed of fibres
disposed in a circular or spiral direction, these being connected together by
vertical 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 ;
and 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, which is attached to the condyloid
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 inter-
muscular septum extends from the lower part of the anterior bicipital ridge, along
the external condyloid 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, thicker than the preceding, extends from the lower part of the
posterior bicipital ridge below the Teres major, along the internal condyloid
ridge to the inner condyle ; it is blended with the tendon of the Coraco-brachialis,
ANTERIOR HUMERAL REGION. 303
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 takes attachment to all the prominent
points round this joint, and is continuous with the fascia of the forearm. On the
removal of this fascia, the muscles of the anterior humeral region are exposed.
The Cor aco -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 downwards,
backwards, and a little outwards, to be inserted by means of a flat tendon into a
rough ridge at the middle of the inner side of the shaft of the humerus. It is
perforated by the musculo-cutaneous- nerve. The inner border of the muscle
forms a guide to the performance of the operation of tying the brachial artery in
the upper part of its course.
Relations. By its anterior surface, with the Deltoid and Pectoralis major above; •
at its insertion it is crossed by the brachial vessels and median nerve. By its ""■»'-
posterior surface, with the tendons of the Subscapularis, Latissimus dorsi, and
Teres major, the short head of the Triceps, the humerus, and the anterior circumflex
vessels. By its inner border, with the brachial artery, and the median and mus-
culo-cutaneous nerves. By its outer border, with the short head of the Biceps
and Brachialis anticus.
The Biceps is a long fusiform muscle, situated along the anterior aspect of the
arm in its entire length, and divided above into two portions or heads, from which
circumstance it has received its name. The short head arises by a thick flattened
tendon from the apex of the coracoid process, in common with the Coraco-
brachialis. The long head arises from the upper margin of the glenoid cavity,
by a long rounded tendon, which is continuous with the glenoid ligament. This
tendon arches over the head of the humerus, being inclosed in a special sheath of
the synovial membrane of the shoulder -joint ; it then pierces the capsular ligament
at its attachment to the humerus, and descends in the bicipital groove in which
it is retained by a fibrous prolongation from the tendon of the Pectoralis major.
The fibres from this tendon form a rounded belly, and, about the middle of the
arm, join with the short portion of the muscle. The belly of the muscle, narrow
and somewhat flattened, terminates above the elbow in a flattened tendon, which
is inserted into the back part of the tuberosity of the radius, a synovial bursa
being interposed between the tendon and the front of the tuberosity. The tendon
of the muscle is thin and broad ; as it approaches the radius it becomes narrow
and twisted upon itself, being applied by a flat surface to the back part of the
tuberosity, and opposite the bend of the elbow gives off, from its inner side, a
broad aponeurosis, which passes obliquely downwards and inwards across the
brachial artery, and is continuous with the fascia of the forearm. The inner
border of this muscle forms a guide to the performance of the operation of tying
the brachial artery in the middle of the arm.1
Relations. Its anterior surface is overlapped above by the Fectoralis 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 on the shoulder-joint and humerus,
from which it is separated by the Subscapularis, Teres major, Latissimus dorsi,
Brachialis anticus, and the musculo-cutaneous nerve. Its inner border is in rela-
tion with the Coraco-brachialis, the brachial vessels, and median nerve. By its
outer border, with the Deltoid and Supinator longus.
1 A third head to the Biceps is occasionally found (Theile says as often as once in eight or
nine subjects), arising at the upper and inner part of the Brachialis anticus with the fibres of
which it is continuous, and is inserted into the bicipital fascia, and inner side of the tendon of the
Biceps. In most cases this additional slip passes behind the brachial artery in its course down
the arm. Occasionally the third head consists of two slips, which pass down, one in front, the
other behind the artery, concealing this vessel in the lower half of the arm.
304 MUSCLES AND FASCIA.
The Brackialis Anticus 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 arises
from the lower half of the outer and inner surfaces of the shaft of the humerus,
commencing above at the insertion of the Deltoid, which it embraces by two
angular processes, and extending, below, to within an inch of the margin of the
articular surface, and being limited on each side by the external and internal
borders. It also arises from the intermuscular septa on each side, but more
extensively from the inner than the outer. Its fibres converge to a thick tendon,
which is inserted into a rough depression on the under surface of the coronoid
process of the ulna, being received into an interval between two fleshy slips of
the Flexor digitorum profundus.
delations. 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 Tnusculo-cutaneous
nerve. The Brachialis anticus receives an additional filament from the musculo-
spiral.
Actions. The Coraco-brachialis draws the humerus forwards and inwards, and
at the same time assists in elevating it towards the scapula. The Biceps and
Brachialis anticus are flexors of the forearm ; the former muscle is also a supi-
nator, and serves to render tense the fascia of the forearm by means of the broad
aponeurosis given off from its tendon. When the forearm is fixed, the Biceps
and Brachialis anticus flex the arm upon the forearm, as is seen in efforts of
climbing. The Brachialis anticus forms an important defence to the elbow-joint.
Posterior Humeral Eegion.
Triceps. Subanconeus.
The Triceps is situated on the back of the arm, extending the entire length of
the posterior surface of the humerus. It is of large size, and divided above into
three parts; hence the name of the muscle. These three portions have been
named, the middle or long head, the external, and the internal head.
The middle or long head arises, by a flattened tendon, from a rough triangular
depression, immediately below the glenoid cavity, being blended at its upper part
with the capsular and glenoid ligaments ; the muscular fibres pass downwards
between the two other portions of the muscle, and join with them in the common
tendon of insertion.
The external head 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 external intermuscular
septum ; the fibres from this origin converging towards the common tendon of
insertion.
The internal head 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
and internal intermuscular septum. The fibres of this portion of the muscle are
directed, some downwards 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 sub-
cutaneous, 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
POSTERIOR HUMERAL REGION. 305
receiving the attachment of the muscular fibres, they join together above the
elbow, and are inserted into the back part of the upper surface of the olecranon
process, a small bursa, occasionally multilocular, being interposed between the
tendon and the front of this surface.
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. 171). The
triangular space transmits the dorsalis scapulae vessels ; it is bounded by the Teres
minor above, the Teres major below, and the scapular head of the Triceps, ex-
ternally : the quadrangular space transmits the posterior circumflex vessels and
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. Its posterior surface is overlapped by the Deltoid above, superficial
in the rest of its extent. 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.
The Subanconeus is a small muscle, distinct from the Triceps, and analogous to
the Subcrureus in the lower limb. It may be exposed by removing the Triceps
from the lower part of the humerus. It consists of one or two slender fasciculi,
which arise from the humerus, immediately above the olecranon fossa, and are
inserted into the posterior ligament of the elbow-joint.
Nerves. The Triceps and Subanconeus are supplied by the musculo-spiral
nerve.
Actions. The Triceps is the great Extensor muscle of the forearm ; when the
forearm is flexed, it serves to draw it into a right line with the arm. It is the
direct antagonist of the Biceps and Brachialis anticus. When the arm is extended,
the long head of the muscle may assist the Teres major and Latissimus dorsi in
drawing the humerus backwards. The long head of the Triceps protects the
under part of the shoulder-joint, and prevents displacement of the head of the
humerus downwards and backwards.
Muscles of the Forearm.
Dissection. To dissect the forearm, place the limb in the position indicated in fig. 168 ; make
a vertical incision along the middle line from the elbow to the wrist, and connect each extremity
with a transverse incision; the .flaps of integument being removed, the fascia of the forearm is
exposed.
The deep fascia of the forearm, continuous above with that inclosing the arm,
is a dense highly glistening aponeurotic investment, which forms a general sheath
inclosing 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 inter-
muscular septa, which inclose each muscle separately. It consists of circular and
oblique fibres, connected together at right angles by numerous vertical fibres. It
is much thicker on the dorsal than on the palmar surface, and at the lower than
at the upper part of the forearm, and is strengthened by tendinous fibres, derived
from the Brachialis anticus and Biceps in front, and from the Triceps behind.
Its inner 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 fibrous cavities, in which the muscles in this region are contained.
Besides the vertical septa separating each muscle, transverse septa are given off
both 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
20
306 MUSCLES AND FASCIJE.
the region they occupy. One group occupies the inner and anterior aspect of the
forearm, and comprises the Flexor and Pronator muscles. Another group oc-
cupies the outer side of the forearm ; and a third, its posterior aspect. The two
latter groups include all the Extensor and Supinator muscles.
Anterior Brachial Begion.
Fig. 172..
arm.
-Front of the Left Fore-
Superficial Muscles.
Superficial Layer.
Pronator radii teres.
Flexor carpi radialis.
Palmaris longus.
Flexor carpi ulnaris.
Flexor sublimis digitorum.
These muscles take origin from
the internal condyle by a common
tendon.
The Pronator Radii Teres arises by
two heads. One, the largest and most
superficial, 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 inter-
muscular septum between it and the
Flexor carpi radialis. The other head
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
passes the median nerve. 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
ridge at the middle of the outer surface
of the shaft of that bone.
Relations. By its anterior surface,
with the deep fascia, the Supinator
longus, and the radial vessels and
nerve. By its posterior surface, with
the Brachialis anticus, Flexor sublimis
digitorum, the median nerve, and ulnar
artery. 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.
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
forearm, and from the intermuscular septa between it and the Pronator radii teres,
on the inside; the Palmaris longus, externally; and the Flexor sublimis digitorum,
beneath. Slender and aponeurotic in structure at its commencement, it increases
ANTERIOR BRACHIAL REGION. 307
in size, and terminates in a tendon which forms the lower two-thirds of its struc-
ture. This tendon passes through a canal on the outer side of the annular liga-
ment, runs through a groove in the os trapezium, converted into a canal by a
fibrous sheath lined by a synovial membrane, and is inserted into the base of
the metacarpal bone of the index-finger. The radial artery lies between the
tendon of this muscle and the Supinator longus, and may easily be secured in
this situation.
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, the median nerve
below.
The Palmaris Longus is a slender fusiform muscle, lying on the inner side of
the preceding. It arises from the inner condyle of the humerus by the common
tendon, from the deep fascia, and intermuscular septa between it and the adjacent
muscles. It terminates in a slender flattened tendon, which is inserted into the
annular ligament, expanding to end in the palmar fascia.
Variation!1;. This muscle is often absent; when present, it exhibits many varieties. Its fleshy
belly is sometimes very long, or it may occupy the middle of the muscle, which is tendinous at
either extremity ; or it may be muscular at its lower extremity, its upper part being tendinous.
Occasionally there is a second Palmaris longus placed on the inner side of the preceding, termi-
nating, below, partly in the annular ligament or fascia, and partly in the small muscles of the
little finger.
Relations. By its anterior surface, with the deep fascia. By its posterior surface,
with the Flexor sublimis digitorum. Internally, with the Flexor carpi ulnarisi
Externally, with the Flexor carpi radialis.
The Flexor Carpi Ulnaris lies along the ulnar side of the forearm. It arises by
two heads, separated by a tendinous arch, beneath which passes the ulnar nerve,
and posterior ulnar recurrent artery. One head arises from the inner condyle of
the humerus, by the common tendon ; the other, from the inner margin of the
olecranon, by an aponeurosis from the upper two-thirds of the posterior border of
the ulna, 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, some fibres
being prolonged to the annular ligament and base of the metacarpal bone of the
little finger. 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 to the opera-
tion of including this vessel in a ligature in this situation.
Relations. By its anterior surface, with the deep fascia, with which it is
intimately connected for a considerable extent. By its posterior surface, with the
Flexor sublimis, the Flexor profundus, the Pronator quadratus, and the ulnar
vessels and nerve. By its outer or radial border, with the Palmaris longus, above;
with the ulnar vessels and nerve, below.
The Flexor Digitorum Sublimis is placed beneath the preceding muscles ; these
therefore require to be removed before its attachment is brought into view. It
is the largest of the muscles of the superficial layer, and arises by three heads.
One from the internal condyle of the humerus by the common tendon, from the
internal lateral ligament of the elbow-joint, and from the intermuscular septum
common to it and the preceding muscles. The second head arises from the inner
side of the coronoid process of the ulna, above the ulnar origin of the Pronator
radii teres. The third head arises from the oblique line of the radius, extending
from the tubercle to the insertion of the Pronator radii teres. The fibres pass
vertically downwards, forming a broad and thick muscle, which divides into four
tendons about the middle of the forearm; as these tendons pass beneath the
annular ligament into the palm of the hand, they are arranged in pairs, the anterior
pair corresponding to the middle and ring fingers; the posterior pair to the index
308 MUSCLES AND FASCIAE.
and little fingers. The tendons diverge from one another as thej pass onwards,
and are finally inserted into the lateral margins of the second phalanges, about
their centre. Opposite the base of the first phalanges, each tendon divides, so as
to leave a fissured interval, between which passes one of the tendons of the Flexor
profundus, and they both enter an osseo-aponeurotic canal, formed by a strong
fibrous band which arches across them, and is attached on each side to the margins
of the phalanges. The two portions into which the tendon of the Flexor sublimis
divides, so as to admit of the passage of the deep flexor, expand somewhat, and
form a grooved channel, into which the accompanying deep flexor tendon is
received ; the two divisions then unite, and finally subdivide a second time to be
inserted into the fore part and sides of the second phalanges. The tendons, whilst
contained in the fibro-osseous canals, are connected to the phalanges by slender
tendinous filaments, called vincula accessoria tendinum. A synovial sheath invests
the tendons as they pass beneath the annular ligament ; a prolongation from which
surrounds each tendon as it passes along the phalanges.
Relations. In the Forearm. By its anterior surface, with the deep fascia and
all the preceding superficial muscles. By its posterior 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.
Anterior Brachial Eegiox.
Deep Layer.
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 (perforans) is situated on the ulnar side of the
forearm, immediately beneath the superficial Flexors. It arises from the upper
two-thirds of the anterior and inner surfaces of the shaft of the ulna, embracing,
above, the insertion of the Brachialis anticus, 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 aponeurosis from the upper two-thirds
of the posterior border of the ulna, and from the ulnar half of the interosseous
membrane. The fibres form a fleshy belly of considerable size, which divides
into four tendons, which pass under the annular ligament beneath the tendons
of the Flexor sublimis. Opposite the first phalanges, the tendons pass between
the two slips of the tendons of the Flexor sublimis, and are finally inserted into
the bases of the last phalanges. The tendon of the index finger is distinct ; the
rest are connected together by cellular tissue and tendinous slips, as far as the
palm of the hand.
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 anterior 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
posterior 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.
ANTERIOR BRACHIAL REGION.
309
The Flexor Longus Polli-
cis is situated on the radial
side of the forearm, lying on
the same plane as the preced-
ing. It arises from the up-
per two-thirds of the grooved
anterior surface of the shaft
of the radius; commencing,
above, immediately below the
tuberosity and oblique line,
and extending, below, to with-
in a short distance of the
Pronator quadratus. It also
arises from the adjacent part
of the interosseous membrane,
and occasionally by a fleshy
slip from the inner side of the
base of the coronoid process.
The fibres pass downwards
and terminate in a flattened
tendon, which passes beneath
the annular ligament, is then
lodged in the interspace be-
tween the two heads of the
Flexor brevis pollicis, and
entering a tendino-osseous ca-
nal, similar to those for the
other flexor tendons, is in-
serted into the base of the last
phalanx of the thumb.
Relations. By its anterior
surface, with the Flexor sub-
limis digitorum, Flexor carpi
radialis, Supinator longus, and
radial vessels. By its poste-
rior surface, with the radius,
interosseous membrane, and
Pronator 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
is a small, flat muscle, quadri-
lateral in form, extending
transversely across the front
of the radius and ulna, above
their carpal extremities. It
arises from the oblique line
on the lower fourth of the
anterior surface of the shaft
of the ulna, and the surface of
bone immediately below it;
from the internal body of the
ulna; and from a strong apo-
neurosis which covers the
Fig. 173. — Front of the Left Forearm. Deep Muscles.
310 MUSCLES AND FASCIAE.
inner third of the muscle. The fibres pass horizontally outwards, to be inserted
into the lower fourth of the anterior surface and external border of the shaft of
the radius.
Relations. By its anterior surface, with the Flexor profundus digitorum, the
Flexor longus pollicis, Flexor carpi radialis, and the radial vessels. By its poste-
rior surface, with the radius, ulna, and interosseous membrane.
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. Of the
deep layer, the Flexor profundus digitorum is supplied conjointly by the ulnar
and anterior interosseous nerves, the Flexor longus pollicis and Pronator quadratus
by the anterior interosseous nerve.
Actions. These muscles act upon the forearm, the wrist, and hand. Those
acting on the forearm are the Pronator radii teres and Pronator quadratus, which
rotate the radius upon the ulna, rendering the hand prone ; when pronation has
been fully effected, the Pronator radii teres assists the other muscles in flexing the
forearm. The flexors of the wrist are the Flexor carpi ulnaris and radialis, and
the flexors of the phalanges are the Flexor sublimis and Profundus digitorum ;
the former flexing the second phalanges, and the latter the last. The Flexor longus
pollicis flexes the last phalanx of the thumb. The three latter muscles, after flex-
ing the phalanges, by continuing their action, act upon the wrist, assisting the
ordinary flexors of this joint ; and all assist in flexing the forearm upon the arm.
The Palmaris longus is a tensor of the palmar fascia ; when this action has been
fully effected, it flexes the hand upon the forearm.
Badial Begiox.
Supinator Longus. Extensor Carpi Badialis Longior.
Extensor Carpi Badialis Brevior.
Dissection. Divide the internment 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,
they should be removed, when the muscles of this region will be exposed. The removal of the
fascia will be considerably facilitated by detaching it from below upwards. Great care should be
taken to avoid cutting across the tendons of the muscles of the thumb.
The Supinator Longus is the most superficial muscle on the radial side of the
forearm, fleshy for the upper two-thirds of its extent, tendinous below. It arises
from the upper two-thirds of the external condyloid 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 base of the styloid process of the radius.
Relations. By its superficial surface, with the integument and fascia for the
greater part of its extent ; near its insertion it is crossed by the Extensor ossis-- -
metacarpi pollicis and the Extensor primi internodii pollicis. By its deep surface,
with the humerus, the Extensor carpi radialis longior and brevior, the insertion of
the Pronator radii teres, and the Supinator brevis. By its inner border, above the
elbow, with the Brachialis anticus, the musculo-spiral nerve, and radial recurrent
artery ; and in the forearm, with the radial vessels and nerve.
The Hlxtensor Carpi Radialis Longior is placed partly beneath the preceding
muscle. It arises from the lower third of the external condyloid ridge of the
humerus, and from the external intermuscular septum. 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 Extensor carpi radialis brevior, immediately behind
the styloid process ; and is inserted into the base of the metacarpal bone of the
index-finger, its radial side.
Relations^ By its superficial surface, with the Supinator longus, and fascia
of the forearm. Its outer side is crossed obliquely by the extensor tendons of
RADIAL REGIOX.
311
the thumb. By its deep
surface, with the elbow-joint,
the Extensor carpi radialis
brevior, and back part of the
wrist.
The Extensor Carpi Ra-
dialis Brevior 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 muscles next to be de-
scribed ; from the external late-
ral ligament of the elbow-joint;
from a strong aponeurosis
which covers its 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, accompanies
it to the wrist, lying in the
same groove on the posterior
surface of the radius; passes
beneath the annular ligament,
and, diverging somewhat from
its fellow, is inserted into the
base of the metacarpal bone
of the middle finger, its radial
side.
The tendons of the two pre-
ceding muscles pass through
the same compartment of the
annular ligament, are lubri-
cated by a single synovial
membrane, but 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 super-
ficial surface, with the Ex-
tensor carpi radialis longior,
and crossed by the Extensor
muscles of the thumb. 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 communis digito-
rum.
Fig. 174.— Posterior Surface of Forearm. Superficial Muscles.
312 MUSCLES AND FASCIA.
Posterior Brachial Eegion-.
Superficial Layer.
Extensor Communis Digitorum. Extensor Carpi Ulnaris.
Extensor Minimi Digiti. Anconeus.
The Extensor Communis Digitorum 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 intermuscular septa between it and the adjacent muscles.
Just below the middle of the forearm it divides into three tendons, which 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 : Each tendon, opposite its corresponding metacarpo-phalangeal articula-
tion, becomes narrow and thickened, gives off a thin fasciculus upon each side of
the joint, and 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 ten-
dons of the Interossei and Lumbricales, Opposite the first phalangeal joint, this
aponeurosis divides into three slips, a middle, and two lateral ; the former is in-
serted into the base of the second phalanx ; and the two lateral, which are continued
onwards along the sides of the second phalanx, unite by their contiguous margins,
and are inserted into the upper surface of the last phalanx. The tendons of the
middle, ring, and little fingers are connected together, as they cross the hand, by
small oblique tendinous slips. The tendons of the index and little fingers also
receive, before their division, the special extensor tendons belonging to them.
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, posterior
interosseous vessels and nerve, the wrist-joint, carpus, metacarpus, and phalanges.
By its radial border, with the Extensor carpi radialis brevior. By its ulnar
border, with the Extensor minimi digiti, and Extensor carpi ulnaris.
The Extensor Minimi Digiti is a slender muscle, placed on the inner side of
the Extensor communis, with which it is generally 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, subdivides into two
as it crosses the hand, and, at the metacarpo-phalangeal articulation, unites with
the tendon derived from the long Extensor. The common tendon then spreads
into a broad aponeurosis, which is inserted into the second and third phalanges of
the little finger in a similar manner to the common extensor tendons of the other
fingers.
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 ; from the middle third of the posterior border of the ulna below the An-
coneus, and from the 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 base of
the metacarpal bone of the little finger.
Relations. By its superficial surface, with the fascia of the forearm. By its
deep surface, with the ulna, and the muscles of the deep layer.
The Anconeus 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 third 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 inwards.
POSTERIOR BRACHIAL REGION". 313
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.
Posterior Brachial Region".
Deep Layer.
Supinator Brevis. Extensor Primi Internodii Pollicis.
Extensor Ossis Metacarpi Pollicis. Extensor Secundi Internodii Pollicis.
Extensor Indicis.
The Supinator Brevis is a broad muscle, of a hollow cylindrical form, curved
round the upper third of the radius. It arises from the external condyle of the
humerus, from the external lateral ligament of the elbow-joint, and the orbicular
ligament of the radius, from an oblique ridge on the ulna, extending down from
the posterior extremity of the lesser sigmoid cavity, and from the triangular
depression in front of it ; and it also arises from a tendinous expansion which covers
its surface. The muscle surrounds the upper part of the radius ; the upper fibres
forming a sling-like fasciculus, which encircles the neck of the radius above the
tuberosity, to be attached to the back part of its inner surface ; the middle fibres
are attached to the outer edge of the bicipital tuberosity ; the lower fibres to the
oblique line, as low down as the insertion of the Pronator radii teres. This
muscle is pierced by the posterior interosseous nerve.
Relations. By its superficial surface, with the superficial Extensor and Supi-
nator 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 is the most external and the largest of
the deep Extensor muscles, lying immediately below the Supinator brevis, with
which it is sometimes united. It arises from the posterior surface of the shaft of
the ulna below the origin of the Anconeus, from the interosseous ligament, and
from the middle third of the posterior surface of the shaft of the radius. Passing
obliquely downwards and outwards, 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 primi internodii pollicis, and is inserted into the base
of the metacarpal bone of the thumb.
Relations. By its superficial surface, with the Extensor communis digitorum,
Extensor minimi digiti, and fascia of the forearm ; being crossed by the branches
of the posterior interosseous artery and nerve. By its deep surface, with the ulna,
interosseous membrane, radius, the tendons of the Extensor carpi radialis longior
and brevior ; 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
primi internodii pollicis.
The Extensor Primi Internodii Pollicis, 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, and from the interosseous
membrane. Its direction is similar to that of the Extensor ossis metacarpi, 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 Secundi Internodii Pollicis is much larger than the preceding
muscle, the origin of which it partly covers in. It arises from 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 narrow oblique
groove at the back part of the lower end of the radius. It then crosses obliquely
the Extensor tendons of the carpus, 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.
314
MUSCLES AND FASCIA.
Relations. By its superficial surface, with the same parts as the Extensor ossis
metacarpi pollicis. By its deep surface, with the ulna, interosseous membrane,
radius, the wrist, the radial vessels, and metacarpal bone of the thumb.
The HJxtensor Indicis 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
Fig. 375. — Posterior Surface of the Forearm. Deep Muscles. Gf the Extensor secundi inter-
nodii pollicis, and from the
interosseous membrane. Its
tendon passes with the Ex-
tensor communis digitorum
through the same canal in the
annular ligament, and subse-
quently joins that tendon of
the Extensor communis which
belongs to the index-finger,
opposite the lower end of
the corresponding metacarpal
bone. It is finally inserted
into the second and third pha-
langes of the index-finger, in
the manner already described.
Relations, They are simi-
lar to those of the preceding
muscles.
Nerves. The Supinator lon-
gus, Extensor carpi radialis
longior, and Anconeus, are
supplied by branches from the
musculo- spiral nerve; the re-
maining muscles of the ra-
dial and posterior brachial
regions, by the posterior inter-
osseous nerve.
Actions. The muscles of
the radial and posterior bra-
chial regions, which comprise
all the Extensor and Supinator
muscles, act upon the fore-
arm, wrist, and hand; they
are the direct antagonists of
the Pronator and Flexor
muscles. The Anconeus as-
sists the Triceps in extending
the forearm. The Supinator
longus and brevis are the
supinators of the forearm and
hand ; the former muscle more
especially acting as a supina-
tor when the limb is pronated.
When supination has been
produced, the Supinator lon-
gus, if still continuing to act,
flexes the forearm. The Ex-
tensor carpi radialis longior
and brevior, and Extensor
carpi ulnaris muscles, are the
OF THE HAXD.
315
Extensors of the wrist ; continuing their action, they serve to extend the forearm
upon the arm ; they are the direct antagonists of the Flexor carpi radialis and
ulnaris. The common Extensor of the fingers, the Extensors of the thumb, and
the Extensors of the index and little fingers, serve to extend the phalanges into
which they are inserted ; and are the direct antagonists of the Flexors. By con-
tinuing their action, they assist in extending the forearm. The Extensors of the
thumb may assist in supinating the forearm, when this part of the hand has been
drawn inwards towards the palm, on account of the oblique direction of the tendons
of these muscles.
Muscles and Fasciae of the Hand.
Dissection (fig. 168). 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 posterior annular
ligaments, and the palmar fascia, should first be dissected.
The Anterior Annular Ligament is a strong fibrous band, which arches over
the carpus, converting the deep groove on the front of these bones into a canal,
beneath which pass the flexor tendons of the fingers. It is attached, internally,
to the pisiform bone, and unciform process of the unciform ; and externally, to the
tuberosity of the scaphoid, and ridge on the trapezium. It is continuous, above,
with the deep fascia of the forearm, and, below, with the palmar fascia. It is
crossed by the tendon of the Palmaris longus, by the ulnar vessels and nerve, and
the cutaneous branches of the median and ulnar nerves. It has inserted into its
upper and inner part, the tendon of the Flexor carpi ulnaris ; and has, arising
from it below, the small muscles of the thumb and little finger. It is pierced by
the tendon of the Flexor carpi radialis ; and, beneath it, pass the tendons of the
Flexor sublimis and Flexor profundus digitorum, the Flexor longus pollicis, and
the median nerve. There are two synovial membranes beneath this ligament ; one
of large size, inclosing the tendons of the Flexor sublimis and Flexor profundus ;
and a separate one for the tendon of the Flexor longus pollicis ; the latter is also
large and very extensive, reaching from above the wrist to the extremity of the
last phalanx of the thumb.
The Posterior Annular Liga-
ment is a strong fibrous band,
extending transversely across
the back of the wrist, and con-
tinuous with the fascia of the
forearm. It forms a sheath for
the Extensor tendons in their
passage to the fingers, being
attached, internally, to the ulna,
the cuneiform and pisiform
bones, and palmar fascia; ex-
ternally, 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 com-
partments for the passage of
tendons, each, of which is. lined
by a separate synovial mem-
brane. These are, from without inwards — 1. On the outer side of the styloid pro-
cess for the tendons of the Extensor ossis metacarpi pollicis, and Extensor primi
internodii pollicis. 2. Behind the styloid process, for the tendons of the Extensor
carpi radialis longior and brevior. 3. Opposite the outer side of the posterior
surface of the radius, for the tendon of the Extensor secundi internodii pollicis.
Fig. 176. — Transverse section through the Wrist, show-
ing the Posterior Annular Ligament, and the canals
for the passage of the Extensor Tendons.
^iwt, nxj- c"" "' o.
*yt COM. DlC
"T- INDlCli.
•HUK.*.**
316 MUSCLES AND FASCIAE.
4. To the inner side of the latter, for the tendons of the Extensor communis
digitorum, and Extensor indicis. 5. For the Extensor minimi digiti, opposite the
interval between the radius and ulna. 6. For the tendon of the Extensor carpi
ulnaris, grooving the back of the ulna. The synovial membranes lining these
sheaths are usually very extensive, reaching from above the annular ligament
down upon the tendons, almost to their insertion.
The palmar fascia 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 in this situation. It is
narrow above, being attached to the lower, margin of the annular ligament, and
receives the expanded tendon of the Palmaris longus muscle. Below, it is broad
and expanded, and opposite the heads of the metacarpal bones divides into four
slips, for the four fingers. Each slip subdivides into two processes, which inclose
the tendons of the Flexor muscles, and are attached to the sides of the first pha-
lanx, and to the glenoid ligament ; by this arrangement, four arches are formed,
under which the Flexor tendons pass. The intervals left in the fascia between
the four fibrous slips transmit the digital vessels and nerves, and the tendons of
the Lumbricales. At the point 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 numerous fibrous
bands, 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 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 middle portion of the palmar fascia.
Muscles of the Hand.
The muscles of the hand are subdivided into three groups. — 1. Those of the
thumb, which occupy the radial side. 2. Those of the little finger, which occupy
the ulnar side. 3. Those in the middle of the palm and between the interosseous
spaces.
Radial Region".
Muscles of the Thumb.
Abductor Pollicis.
Opponens Pollicis or Flexor Ossis Metacarpi.
Flexor Brevis Pollicis.
Adductor Pollicis.
The Abductor Pollicis is a thin, flat muscle, placed immediately beneath the
integument. It arises from the ridge of the os trapezium and annular ligament ;
and, passing outwards and downwards, is inserted by a thin, flat tendon into the
radial side of the base of the first phalanx of the thumb.
Relations. By its superficial surface, with the palmar fascia. By its deep sur-
face, 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.
The Opponens Pollicis is a small triangular muscle, placed beneath the pre-
ceding. It arises from the palmar surface of the trapezium and annular ligament:
passing downwards and outwards, it is inserted into the whole length of the meta-
carpal bone of the thumb on its radial side.
Relations. By its superficial surface, with the Abductor pollicis. By its deep
OF THE HAND.
31T
surface, with the trapezio-metacarpal articulation. By its inner border, with the
Flexor brevis pollicis.
The Flexor Brevis Pollicis is much larger than either of the two preceding
muscles, beneath which it is placed. It consists of two portions, in the interval
between which lies the tendon of the Flexor longus pollicis. The anterior and
Fig. 177. — Muscles of the Left Hand. Palmar Surface.
more superficial portion arises from the trapezium and outer two-thirds of .the
annular ligament; the deeper portion from the trapezoides, os magnum, base
of the third metacarpal bone, and sheath of the tendon of the Flexor carpi radialis.
The fleshy fibres unite to form a single muscle ; this divides into two portions,
318 MUSCLES AND FASCIAE.
winch are inserted one on either side of the base of the first phalanx of the thumb,
the outer portion being joined with the Abductor, and the inner with the Adductor.
A sesamoid bone is developed in each tendon as it passes across the metacarpo-
phalangeal joint.
Relations. By its superficial surface, with the palmar fascia. By its deep sur-
face, with the Adductor pollicis, and tendon of the Flexor carpi radialis. By its
external surface, with the Opponens pollicis. By its internal surface, with the
tendon of the Flexor longus pollicis.
The Adductor Pollicis (fig. 173) is the most deeply seated of this group of
muscles. It is of a triangular form, arising, by its broad base, from the whole
length of the metacarpal bone of the middle finger on its palmar surface ; the
fibres, proceeding outwards, converge, to be inserted with the innermost tendon of
the Flexor brevis pollicis, into the ulnar side of the base of the first phalanx of
the thumb, and into the internal sesamoid bone.
Relations. By its superficial surf ace, with the Flexor brevis pollicis, the tendons
of the Flexor profundus and Lumbricales. Its deep surface covers the first two
interosseous spaces, from which it is separated by a strong aponeurosis.
Nerves. The Abductor, Opponens, and outer head of the Flexor brevis pollicis,
are supplied by the median nerve; the inner head of the Flexor brevis, and the
Adductor pollicis, by the ulnar nerve.
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, the Flexor ossis metacarpi or Opponens pollicis, the Flexor brevis pollicis,
and the Flexor longus pollicis; there is also an Abductor and an Adductor.
These muscles give to the thumb that extensive range of motion which it pos-
sesses in an eminent degree.
Ulnar Region.
Muscles of the Little Finger.
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
annular ligament and palmar fascia ; the fleshy fibres pass horizontally inwards,
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 is situated on the ulnar border of the palm of the
hand. It arises from the pisiform bone, and from an expansion of the tendon of
the Flexor carpi ulnaris ; and terminates in a flat tendon, which is inserted into
the ulnar side of the base of the first phalanx of the little finger.
Relations. By its superficial surface, with the inner portion of the palmar
fascia, and the Palmaris brevis. By its deep surface, with the Flexor ossis meta-
carpi. By its inner border, with the Flexor brevis minimi digiti.
The Flexor Brevis Minimi Digiti lies on the same plane as the preceding muscle,
on its radial side. It arises from the tip of the unciform process of the unciform
bone, and anterior surface of the annular ligament, and is inserted into the base of
the first phalanx of the little finger, with the preceding. 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.
OF THE HAND.
319
Relations. By its superficial surface, with the internal portion of the palmar
fascia, and the Palmaris brevis. By its deep surface, with the Flexor ossis meta-
carpi.
The Opponens Minimi Digiti (fig. 173), is of a triangular form, and placed im-
mediately beneath the preceding muscles. It arises from the unciform process of
the unciform bone, and contiguous portion of the annular ligament ; its fibres pass
downwards and inwards, 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 fifth
metacarpal space, the metacarpal bone, and the Flexor tendons of the little
finger.
Nerves. All the muscles of this group are supplied by the ulnar nerve.
Actions. The actions of the muscles of the little finger are expressed in their
names. The Palmaris brevis corrugates the skin on the inner side of the palm
of the hand.
Middle Palmar Eegion".
Lumbricales. Interossei Palmares.
Interossei Dorsales.
The Lumbricales are four small fleshy fasciculi, accessories to the deep Flexor
muscle. They arise by fleshy fibres 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 ; 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 forwards to the radial side of the corre-
sponding fingers, and opposite the metacarpophalangeal articulations each tendon
terminates in a broad aponeurosis, which
, j • , , r . j • • Fig. 178. — The Dorsal Interossei of Left Hand,
is inserted into the tendinous expansion
from the Extensor communis digitorum,
which covers the dorsal aspect of each
finger.
The Interossei Muscles are so named
from occupying the intervals between the
metacarpal bones. They are divided into
two sets, a dorsal and palmar ; the former
are four in number, one in each meta-
carpal space ; the latter, three in number,
lie upon the metacarpal bones.
The Dorsal Interossei are four in
number, larger than the palmar, and
occupy the intervals between the meta-
carpal bones. They are bipenniform
muscles, arising by two heads from the
adjacent sides of the metacarpal bones,
but more extensively from that side of
the metacarpal bone, which corresponds
to the side of the finger in which the
muscle is inserted. They are inserted
into the base 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 which passes a perforating branch from the
deep palmar arch.
The First Dorsal Interosseous muscle or Abductor indicis is larger than the
others, and lies in the interval between the thumb and index-finger. It is flat,
320
SURGICAL ANATOMY.
Fig. 179. — The Palmar Interossei of Left Hand.
triangular in form, and arises by two heads, separated by a fibrous arch, for the
passage of the radial artery into the deep part of 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 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 are inserted into the middle finger, the former into its
radial, the latter into its ulnar side. The fourth is inserted in the ulnar side of
the ring-finger.
The Palmar Interossei, three in number, are smaller than the Dorsal, and placed
upon the palmar surface of the metacarpal bones, rather than between them.
They arise from the entire length of the
metacarpal bone of one finger, and are
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 in-
serted into the same side of the index-
finger. The second arises from the radial
side of the fourth metacarpal bone, and
is inserted into the 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 In-
terossei muscles, with the exception of the
little finger.
Nerves. The two outer Lumbricales
are supplied by the median nerve; the
rest of the muscles of this group, by the
ulnar.
Actions. The Dorsal interossei muscles
abduct the fingers from an imaginary line drawn longitudinally through the centre
of the middle finger ; and the Palmar interossei adduct the fingers towards the
same line. . They usually assist the Extensor muscles ; but when the fingers are
slightly bent, they assist in flexing the fingers.
SURGICAL ANATOMY.
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 ; the causes of displacement are thus easily recognized, and a suitable treatment in each
case may be readily adopted.
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 clavicle is an exceedingly common accident, and is usually caused by indirect
violence, as a fall upon the shoulder ; it occasionally, however, occurs from direct force. Its most
usual situation is just external to the centre of the bone, but it may occur at the sternal or acro-
mial ends.
Fracture of the middle of the clavicle (fig. 180) is always attended with considerable displace-
ment, the outer fragment being drawn downwards, forwards, and inwards ; the inner fragment
slightly upwards. The outer fragment is drawn down by the weight of the arm, and the action
of the Deltoid, and forwards and inwards by the Pectoralis minor and Subclavius muscles; the
inner fragment is slightly raised by the Sterno-cleido-mastoid, but only to a very limited extent,
as the attachment of the costo-clavicular ligament and Pectoralis major below and in front would
prevent any very great displacement upwards. The causes of displacement having been ascer-
tained, it is easy to apply the appropriate treatment. The outer fragment is to be drawn out-
OF THE MUSCLES OF THE UPPER EXTREMITY. 321
wards, and, together with the scapula, raised upwards to a level with the inner fragment, and
retained in that position.
Fig. ISO.— Fracture of the Middle of the
Clavicle.
In fracture of the acromial end of the cla-
vicle between the conoid and trapezoid liga-
ments, only slight displacement occurs, as
these ligaments, from their oblique insertion,
serve to hold both portions of the bone in
apposition. Fracture, also, of the sternal end,
internal to the costoclavicular ligament, is
attended with only slight displacement, this
ligament serving to retain the fragments 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 tho shoulder being
lost, from the Deltoid drawing downwards and
forwards the fractured portion ; and the dis-
placement may easily be discovered by tracing
the margin of the clavicle outwards, 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 forwards across the chest,
and the elbow well raised, so that the head
of the bone may press upwards the acromion
process, and retain it in its position.
Fracture of the coracoid process is an ex-
tremely rare accident, and is usually caused
by a sharp blow on the point of the shoulder.
Displacement is here produced by the com-
bined actions of the Pectoralis minor, short
head of the Biceps, and Coraco-brachialis, the former muscle drawing the fragment inwards, the
latter directly downwards, the amount of displacement being limited by the connection of this
process to the acromion by means of the coraco-acromial ligament. 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 forwards and inwards across the chest so as to relax the
Coraco-brachialis ; tne humerus should then be pushed upwards against the coraco-acromial
ligament, and the arm retained in this position.
, Fracture of the anatomical neck of the humerus within the capsular ligament is a rare accident,
attended with very slight displacement, an impaired condition of the motions of the joint, and
crepitus.
Fracture of the surgical neck (fig. 181) is very common, is attended with considerable displace-
ment, 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 inwards by the Pectoralis
major, Latissimus dorsi, and Teres major;
and the humerus is thrown obliquely outwards
from the side by the Deltoid, and occasionally
elevated so as to project beneath and in front
of the coracoid process. By fixing the shoul-
der, and drawing the arm outwards and
downwards, the deformity is at once reduced.
To counteract the action of the opposing
muscles, and to keep the fragments in posi-
tion, the arm should be drawn from the side,
and pasteboard splints applied on its four
sides ; a large conical-shaped pad should be
placed in the axilla with the base turned
upwards, and the elbow approximated to the
side, and retained there by a broad roller
passed round the chest ; the forearm should
then be flexed, and the hand supported in a
sling, care being taken not to raise the elbow,
otherwise the lower fragment may be displaced
upwards.
21
Fig. 181. — Fracture of the Surgical Neck
of the Humerus.
322
SURGICAL ANATOMY.
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 considerable deformity,
the upper fragment being drawn inwards by the first-mentioned muscles, and the lower fragment
drawn upwards and outwards by the Deltoid, producing shortening of the limb, and a considerable
prominence at the seat of fracture, from the fractured ends of the bone riding over one another,
especially if the fracture takes place in an oblique direction. The fragments may be readily
brought into apposition by extension from the elbow, and retained in that position by adopting
■ the same means as in the preceding injury.
In fracture 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 the fracture occurs
in a transverse direction, only slight displacement occurs, the upper fragment being drawn a
little forwards ; but in oblique fracture, the combined actions of the Biceps and Brachialis anticus
muscles in front, and the Triceps behind, draw upwards the lower fragment, causing it to glide
over the upper fragment, either backwards or forwards, according to the direction of the fracture.
Simple extension reduces the deformity, and the application of splints on the four sides of the
arm retains 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. 182) immediately above the condyles deserves very attentive
consideration, as the general appearances cor-
Fig. 182.— Fracture of the Humerus above the
Condyles.
respond somewhat with those produced by
separation of the epiphysis of the humerus,
and with those of dislocation of the radius
and ulna backwards. If the direction of the
fracture is oblique from above, downwards,
and forwards, the lower fragment is drawn
upwards and backwards by the Brachialis
anticus and Biceps in front, and the Triceps
behind. This injury may be diagnosticated from
dislocation, by the increased mobility in frac-
ture, the existence of crepitus, and the de-
formity being remedied by extension, by the
discontinuance of which it is again reproduced.
The age of the patient is of importance in
distinguishing this form of injury from sepa-
ration of the epiphysis. If fracture occurs
in the opposite direction to that shown in
the accompanying figure, the lower fragment
is drawn upwards and forwards, causing a
considerable prominence in front; and the
upper fragment projects backwards beneath
the tendon of the Triceps muscle.
Fracture of the coronoid process of the ulna
is an accident of rare occurrence, and is
usually caused by violent action of the Bra-
chialis anticus muscle. The amount of dis-
placement varies according to the extent of the fracture. If the tip of the process only is
broken off, the fragment is drawn upwards by the Brachialis anticus on a level with the
coronoid depression of the humerus, and
Fig. 183.— Fracture of the Olecranon. tne power of flexion is partially lost. If
the process is broken off near its root, the
fragment is still displaced by the same
muscle ; at the same time, on extending
the forearm, partial dislocation backwards
of the ulna occurs from the action of the
Triceps muscle. The appropriate treat-
ment would be to relax the Brachialis an-
ticus by flexing the forearm, and to retain
the fragments irt apposition by keeping
the arm in this position. Union is generally
ligamentous.
Fracture of the olecranon process (fig.
183) is a more frequent accident, and is
caused either by violent action of the
Triceps muscle, or by a fall or blow upon
the point of the elbow. The detached
fragment is displaced upwards, 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
OF THE MUSCLES OF THE UPPER EXTREMITY. 323
patient at the same time loses the power of extending the forearm. The treatment consists in
relaxing the Triceps by extending the forearm, and retaining it in this position by means of a
long straight splint applied to the front of the arm ; the fragments are thus brought into closer
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
from the large number of muscles which surround it ; but the movements of pronation and supi-
nation are entirely lost. The upper fragment is drawn outwards by the Supinator brevis, iis
extent of displacement being limited by the attachment of the orbicular ligament. The lower
fragment is drawn forwards and slightly upwards by the Biceps, and inwards by the Pronator
radii teres, its displacement forwards and upwards 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 midway
between pronation and supination, extension having been previously made so as to bring the
parts in apposition.
Fracture of the radius (fig. 184) is more common than fracture of the ulna, on account of the
connection of the former with the wrist. Fracture of the shaft of the radius near its centre may
occur from direct violence, but more fre-
quently from a fall forwards, the entire weight
of the body being received on the wrist and Fig. 184.— Fracture of the Shaft of the Radius.
hand. The upper fragment is drawn up-
wards by the Biceps, and inwards by the
Pronator radii teres, holding a position mid-
way between pronation and supination, and
a degree of fulness in the upper half of the
forearm is thus produced ; the lower frag-
ment is drawn downwards and inwards
towards the ulna by the Pronator quadratus,
and thrown into a state of pronation by the
same muscle ; at the same time, the Supi-
nator longus, by elevating the styloid pro-
cess, into which it is inserted, will serve to
depress still more the upper end of the lower
fragment towards 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 then 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.
Fracture of the shaft of the ulna is not a common accident; it is usually caused by direct vio-
lence. Its more protected position on the inner side of the limb, the greater strength of its shaft,
and its indirect connection with the wrist, render it less liable to injury than the radius. It usu-
ally occurs a little below the centre, which is the weakest part of the bone. The upper fragment
retains it3 usual position ; but the lower fragment is drawn outwards towards the radius by the
Pronator quadratus, producing a well-marked depression at the seat of fracture, and some fulness
on the dorsal and palmar surfaces of the forearm. The fracture is easily reduced by extension
from the wrist and forearm. The forearm should be flexed, and placed in a position midway
between pronation and supination, and well-padded splints applied from the elbow to the ends of
the fingers.
Fracture of the shafts of the radius and ulna together is not a common accident ; it may arise
from a direct blow, or from indirect violence. The lower fragments are drawn upwards, some-
times forwards, sometimes backwards, according to the direction of the fracture, by the combined
actions of the Flexor and Extensor muscles, producing a degree of fulness on the dorsal or pal-
mar surface of the forearm; at the same time the two fragments are drawn into contact by the
Pronator quadratus, the radius in a state of pronation : the upper fragment of the radius is drawn
upwards and inwards 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 the treatment of all cases of fracture of the bones of the forearm, the greatest care is requi-
site to prevent the ends of the bones from being drawn inwards towards the interosseous space :
if this is not carefully attended to, the radius and ulna may become anchylosed, and the move-
ments of pronation and supination entirely lost. To obviate this, the splints applied to the limb
should be well padded, so as to press the muscles down into their normal situation in the interos-
seous space, and so prevent the approximation of the fragments.
Fracture of the lower end of the radius (fig. 185) is usually called Colles's fracture, from the
name of the eminent Dublin surgeon who first accurately described it. It is generally produced
from the patient falling from a height, and alighting upon the hand, which receives the entire
weight of the body. This fracture usually takes place from half an inch to an inch above the
324
MUSCLES AND FASCIAE
articular surface if it occurs in the adult; but in the child, before the age of sixteen, it is more
frequently a separation of the epiphysis from the apophysis. The displacement which is produced
is very considerable, and bears some resemblance to dislocation of the carpus backwards, from
which it should be carefully distinguished. The lower fragment is drawn upwards and backwards
Fig. 185. — Fracture of the Lower End of the Radius.
behind the upper fragment by the combined actions of the Supinator longus and the Flexors and
the Extensors of the thumb and carpus, producing a well-marked prominence on the back of the
wrist, with a deep depression behind. The upper fragment projects forwards, often lacerating
the substance of the Pronator quadratus, and is drawn by this muscle into close contact with the
lower end of the ulna, causing a projection on the anterior surface of the forearm, immediately
above the carpus, from the flexor tendons being thrust forwards. This fracture may be dis-
tinguished 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. The treatment consists
in flexing the forearm; and making powerful extension from the wrist and elbow, depressing at
the same time the radial side of the hand, and retaining the parts in this position by well-padded
pistol-shaped splints.
MUSCLES AND FASCIA OF THE LOWER EXTREMITY.
The Muscles of the Lower Extremity are
ing with the different regions of the limb.
Iliac
region.
Psoas magnus.
Psoas parvus.
Iliacus.
Thigh.
Anterior femoral region.
Tensor vaginae femoris.
Sartorius.
Rectus.
Vastus externus.
Vastus internus.
Crureus.
Subcrureus.
Internal femoral region.
Gracilis.
Pectineus.
Adductor longus.
subdivided into groups, correspond-
Adductor brevis.
Adductor magnus.
Hip.
Gluteal region.
Gluteus maximus.
Gluteus medius.
Gluteus minimus.
Pyriformis.
Gemellus superior.
Obturator internus.
Gemellus inferior.
Obturator externus.
Quadratus femoris.
Posterior femoral region.
Biceps.
Semi-tendinosus.
Semi-membranosus.
OF TIIE LOWER EXTREMITY. 325
Leg. Foot.
Anterior tibio-fibular region. Dorsal region.
Tibialis anticus. Extensor brevis digitorum.
Extensor longus digitorum. Interossei dorsales.
Extensor proprius pollicis. Plantar region.
Peroneus tertius. First layer.
Posterior tibio-fibular region. Abductor pollicis.
Superficial layer. Flexor brevis digitorum.
Gastrocnemius Abductor minimi digiti.
Plantaris. Second layer.
Musculus accessorius.
Deep layer. Lumbricales.
Popliteus. Third layer.
Flexor longus pollicis. Flexor brevis pollicis.
Flexor longus digitorum. Adductor pollicis.
Tibialis posticus. Flexor brevis minimi digiti.
Fibular region. Transversus pedis.
Peroneus longus. Fourth layer.
Peroneus brevis. Interossei plantares.
Iliac Region,
Psoas Magnus. Psoas Parvus. Iliacus.
Dissection. No detailed description is required for the dissection of these muscles. They are
exposed after the removal of the viscera from the abdomen, covered by the peritoneum and a
t!.in layer of fascia, the fascia iliaca.
The iliac fascia is the aponeurotic layer which lines the back part of the
abdominal cavity, and incloses the Psoas and Iliacus muscles throughout their
whole extent. It is thin above; and becomes gradually thicker below, as it
approaches the femoral arch.
The portion investing the Psoas is attached, above, to the ligamentum arcuatum
internum ; internally, to the sacrum ; and by a series of arched processes to the
intervertebral substances, and prominent margins of the bodies of the vertebrae ;
the intervals left opposite the constricted portions of the bodies transmitting the
lumbar arteries and sympathetic filaments of nerves. Externally, it is continuous
with the fascia lumborum.
The portion investing the Iliacus is connected, externall}'-, to the whole length
of the inner border of the crest of the ilium ; internally, to the brim of the true
pelvis, where it is continuous with the periosteum, and receives the tendon of
insertion of the Psoas parvus. External to the femoral vessels, this fascia is
intimately connected with Poupart's ligament, and is continuous with the fascia
transversalis ; but, corresponding to the point where the femoral vessels pass down
into the thigh, it is prolonged down behind them, forming the posterior wall of the
femoral sheath. Below this point, the iliac fascia surrounds the Psoas and Iliacus
muscles to their termination, and becomes continuous with the iliac portion of the
fascia lata. Internal to the femoral vessels the iliac fascia is connected to the ilio-
pectineal line, and is continuous with the pubic portion of the fascia lata. The
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. In abscess accompanying caries of the lower part of the spine, the matter
makes its way to the femoral arch, distending the sheath of the Psoas ; and when
it accumulates in considerable quantity, this muscle becomes absorbed, and the
nervous cords contained in it are dissected out, and lie exposed in the cavity of
the abscess ; the femoral vessels, however, remain intact, and the peritoneum seldom
becomes implicated notwithstanding the extreme thinness of the membrane.
326 MUSCLES AND FASCIAE.
Remove this fascia, and the muscles of the iliac region will be exposed.
The Psoas Magnus (fig. 187) is a long fusiform muscle, placed on the side of
the lumbar region of the spine and margin of the pelvis. It arises from the sides of
the bodies, from the corresponding intervertebral substances, and from the front
of the bases of the transverse processes of the last dorsal and all the lumbar ver-
tebras. The muscle is connected to the bodies of the vertebras by five slips ; each
slip is attached to the upper and lower margins of the two vertebras, and to the
intervertebral substance between them, the slips themselves being connected by
tendinous arches extending across the constricted part of the bodies, beneath which
pass the lumbar arteries and sympathetic nervous filaments. These tendinous arches
also give origin to muscular fibres and protect the bloodvessels and nerves
from pressure during the action of the muscle. The first slip is attached to the
contiguous margins of the last dorsal and first lumbar vertebras ; the last, to the
contiguous margins of the fourth and fifth lumbar, and intervertebral substance.
From these points, the muscle passes down across the brim of the pelvis, and,
diminishing gradually in size, passes beneath Poupart's ligament, and terminates
in a tendon, which, after receiving the fibres of the Iliacus, is inserted into the
I lesser trochanter of the femur.
Relations. In the Lumbar Region. By its anterior surface, which is placed
behind the peritoneum, with the ligamentum arcuatum internum, the kidney, Psoas
parvus, renal vessels, ureter, spermatic vessels, genito-crural nerve, the colon, and,
along its pelvic border, with the common and external iliac artery and vein. By
its posterior surface, with the transverse processes of the lumbar vertebras and the
Quadratus lumborum, from which it is separated by the anterior lamella of the
aponeurosis of the Transversalis ; the anterior crural nerve is at first situated in
the substance of the muscle, and emerges from its outer border at its lower part.
The lumbar plexus is situated in the posterior part of the substance of the muscle.
By its inner side, with the bodies of the lumbar vertebras, the lumbar arteries, the
sympathetic ganglia, and its communicating branches with the spinal nerves ; the
lumbar glands, with the vena cava on the right, and the aorta on the left side. 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, which some-
times communicates with the cavity of the joint through an opening of variable
size. By its inner border, with the Pectineus and the femoral artery, which
slightly overlaps it. By its outer border with the crural nerve and Iliacus muscle.
The Psoas parvus is a long slender muscle, placed in front of the preceding.
It arises from the sides of the bodies of the last dorsal and first lumbar vertebras,
and from the intervertebral substance between them. It forms a small flat
muscular bundle, which terminates in a long, flat tendon, which is inserted into
the ilio-pectineal eminence, being continuous, by its outer border, with the iliac
fascia. This muscle is present, according to M. Theile, in one out of every twenty
subjects examined.
Relations. It is covered by the peritoneum, and at its origin by the ligamentum
arcuatum internum ; it rests on the Psoas magnus.
The Iliacus is a flat radiated muscle, which fills up the whole of the internal
iliac fossa. It arises from the iliac fossa, and 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, the
notch between them, and by a few fibres from the capsule of the hip-joint. The
fibres converge to be inserted into the outer side of the tendon of the Psoas, some
of them being prolonged into the oblique line which extends from the lesser tro-
chanter to the linea aspera.
Relations. Within the Pelvis: 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 cascum ; on the left side, with the sigmoid
flexure of the colon. By its postenor surface, with the iliac fossa. By its inner
border, with the Psoas magnus, and anterior crural nerve. — In the Hugh, it is in
ANTERIOR FEMORAL REGION
327
relation, by its anterior surface, with the fascia lata, Rectus and Sartorius ; behind,
with the capsule of the hip-joint, a synovial bursa common to it and the Psoas
magnus being interposed.
Nerves. The Psose muscles are supplied by the anterior branches of the lumbar
nerves. The Iliacus from the anterior crural.
Actions. The Psoas and Iliacus muscles, acting from above, flex the thigh upon
the pelvis, and, at the same time, rotate the femur outwards, from the obliquity
of their insertion into the inner and back part of that bone. Acting from below,
the femur being fixed, the muscles of both sides bend the lumbar portion of the
spine and pelvis forwards. 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.
Anterior Femoral Region.
Tensor Vaginae Femoris.
Sartorius.
Rectus.
Vastus Externus.
Vastus Internus.
Crureus.
Subcrureus.
Dissection. To expose the muscles and fasciae in this region, an incision should be made
along Poupart's ligament, from the spine of the Ilium to the pubes, from the centre of which a
vertical incision must be carried along the middle Fi 186._Dissection of Lower Extremitv.
line ot the thigh to below the knee-joint, and con- Front View.
nected with a transverse incision, carried from
the inner to the outer side of the leg. The flaps
of integument having been removed, the super-
ficial and deep fasciae should be examined. The
more advanced student would 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 the accompanying figure.
Fascijs of the Thigh.
The superficial fascia forms a continu-
ous layer over the whole of the lower
extremity, and consists of areolar tissue,
containing in its meshes much adipose
matter, and capable of being separated
into two or more layers, between which
are found the superficial vessels and
nerves. It varies in thickness in differ-
ent parts of the limb ; in the sole of the
foot it is so thin as to be scarcely demon-
strable, the integument being closely ad-
herent to the deep fascia beneath, but in
the groin it is thicker, and the two layers
are separated from one another by the
superficial inguinal glands, the internal
saphenous vein, and several smaller ves-
sels. Of these two layers, the most
superficial is continuous above with the
superficial fascia of the abdomen, the deep
layer becoming blended with the fascia
lata, a little below Poupart's ligament.
The deep layer of superficial fascia is in-
timately adherent to the margins of the
4 4
I
/ . Dissection
°f
FEMORAL HERNIA,
fc
SCARPAS TRIANGLE
Z\Z \ 2- FRONTjf THIGH
3 . FRONTrf LEO
/f. . DORSUMgf FOOT
328
MUSCLES AND FASCIA.
Fig. 187.—:
the Iliac and Anterior
. Regions.
««?°/!l
saphenous opening in the fascia lata, and
pierced in this situation by numerous
small bloodvessels and lymphatics, hence
the name cribriform fascia, which has been
applied to it. Subcutaneous bursse are
found in the superficial fascia over the
patella, point of the heel, and phalangeal
articulations of the toes.
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 thickest in the upper and outer
side of the thigh, where it receives a
fibrous expansion from the Gluteus maxi-
mus muscle, and the Tensor vaginae femoris
is inserted between its layers ; it is very
thin behind, and at the upper and inner
side, where it covers the Adductor muscles,
and again becomes stronger around the
knee, receiving fibrous expansions from
the tendon of the Biceps externally, and
from the Sartor ius, Gracilis, Semi-tendi-
nosus, and Quadriceps extensor cruris in
front. The fascia lata is attached, above,
to Poupart's ligament, and crest of the
ilium; behind, to the margin of the sa-
crum and coccyx ; internally, to the pubic
arch and pectineal line ; and below, to all
the prominent points around the knee-
joint, the condyles of the femur, tuberosi-
ties of the tibia, and head of the fibula.
That portion which invests the Gluteus
medius (the Gluteal aponeurosis) is very
thick and strong, and gives origin by its
inner surface, to some of the fibres of
that muscle ; at the upper border of the
Gluteus maximus, it divides into two
layers, the most superficial, very thin,
covering the surface of the Gluteus maxi-
mus, and is continuous below with the
fascia lata; the deep layer being thick above,
and blending with the great sacro-sciatic
ligament, thin below, where it separates
the Gluteus maximus from the deeper
muscles. From the inner surface of the
fascia lata, are given off two strong inter-
muscular septa, which are attached to
the whole length of the linea aspera : the
external and stronger one, which 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 behind, and gives partial origin
to these muscles ; the inner one, the
ANTERIOR FEMORAL REGION. S29
thinner of the two, separates the Vastus internus from the Adductor muscles.
Besides these, there are numerous smaller septa, separating the individual muscles,
and inclosing each in a distinct sheath. At the upper and inner part of the thigh,
a little below Poupart's ligament, a large oval-shaped aperture is observed : it
transmits the internal saphenous vein, and other smaller vessels, and is termed
the saphenous opening. In order more correctly to consider the mode of forma-
tion of this aperture, the fascia lata is described as consisting, in this part of the
thigh, of two portions, an iliac portion, and a pubic portion.
The iliac portion is all that part of the fascia lata placed 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 inter-
nally as the spine of the pubes, and to the pectineal line in conjunction with Gim-
bernat's ligament. From the spine of the pubes, it is reflected downwards and
outwards, forming an arched margin, the superior cornu or outer boundary 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 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 up-
wards, it is seen to cover the surface of the Pectin eus muscle, and passing behind
the sheath of the femoral vessels, to which it is closely united, is continuous with
the sheath of the Psoas and Iliacus muscles, and is finally lost in the fibrous cap-
sule of the hip-joint. This fascia is attached above to the pectineal line in front
of the insertion of the aponeurosis of the External oblique, and internally to the
margin of the pubic arch. From this description it may be observed, that the
iliac portion of the fascia lata passes in front of the femoral vessels, the pubic por-
tion behind them, an apparent aperture consequently existing between the two,
through which the internal saphenous joins the femoral vein.
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 Vaginse Femoris is a short flat muscle, situated at the upper and
outer side of the thigh. It 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, between the Gluteus medius and Sartorius. The muscle passes obliquely
downwards, and a little backwards, to be inserted into the fascia lata, about one-
fourth down the outer side of the thigh.
Relations. By its superficial surface, with the fascia lata and the integument.
By its deep surface, with the Gluteus medius, Rectus femoris, Vastus externus,
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 space,
in which is seen the Rectus femoris. By its posterior border, with the Gluteus
medius.
The Sartorius, the longest muscle in the body, is a flat, narrow, riband-like
muscle, which arises by tendinous fibres from the anterior superior spinous process
of the ilium and upper half of the notch below it ; 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 ob-
liquely forwards, expands into a broad aponeurosis, which is inserted into the
upper part of the inner surface of the shaft of the tibia, nearly as far forwards as
the crest. This expansion covers the insertion of the tendons of the Gracilis and
Semi-tendinosus, with which it is partially united, a synovial bursa being inter-
posed between them. An offset is derived from 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
330 MUSCLES AND FASCIA.
muscle to the femoral artery should be carefully examined, as its inner border
forms the chief guide in the operation of including this vessel in a ligature. In
the upper third of the thigh, it forms, with the Adductor longus, the side of a
triangular space, Scarpa's triangle, the base of which, turned upwards, is formed
by Poupart's ligament : the femoral artery passes perpendicularly through the
centre 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 beneath the Sar-
torius.
Relations. By its superficial surface, with the fascia lata and integument. By
its deep surface, with the Iliacus, Psoas, Kectus, Vastus internus, anterior crural
nerve, sheath of the femoral vessels, Adductor longus, Adductor magnus, Graci-
lis, long saphenous nerve, and internal lateral ligament of the knee-joint.
The Quadriceps extensor 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 tibia, and, above, subdividing into separate portions, which
have received separate 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 condyles to the trochanters. 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 two latter j)ortions are, however, so intimately blended, as to form but one
muscle.
The Rectus femoris is situated in the middle of the anterior region of the thigh ;
it is fusiform in. shape, and its fibres are arranged in a bipenniform manner. It
arises by two tendons ; one, the straight tendon, from the anterior inferior spinous
process of the ilium ; the other is flattened, and curves outwards, to be attached
to a groove above the brim of the acetabulum ; this is the reflected tendon of the
Rectus, uniting with the straight tendon at an acute angle, and then spreading into
an aponeurosis, from which the muscular fibres arise. The muscle terminates in
a broad and thick aponeurosis, which occupies the lower two-thirds of its poste-
rior surface, and, gradually becoming narrowed into a flattened tendon, is inserted
into the patella in common with the Vasti and Crureus.
Relations. By its superficial surface, with the anterior fibres of the Gluteus
medius, the Tensor vaginas femoris, Sartorius, and the Psoas and Iliacus ; by its
lower three-fourths, with the fascia lata. By its posterior surface, with the hip-
joint, the external circumflex vessels, and the Crureus and Vasti muscles.
The three remaining muscles have been described collectively by some anato-
mists, separate from the Eectus, under the name of the Triceps extensor cruris ; in
order to expose them, divide the Sartorius and Rectus muscles across the middle,
and turn them aside, when they will be fully brought into view.
The Vastus externus is the largest part of the Quadriceps extensor. It arises
by a broad aponeurosis, which is attached to the anterior border of the great tro-
chanter, to a horizontal ridge on its outer surface, to a rough line, leading from
the trochanter major to the linea aspera, and to the whole length 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 arise. A few additional fibres come from
the tendon of the Gluteus maximus, and from the external intermuscular septum
between the Vastus externus and short head of the Biceps. These fibres form a
large fleshy mass, which is attached to a strong aponeurosis, placed on the under
surface of the muscle at its lowest part; this becomes contracted and thickened
into a flat tendon, which is inserted into the outer part of the upper border of the
patella, blending with the great Extensor tendon.
Relations. By its superficial surface, with the Rectus, the Tensor vaginas
femoris, the fascia lata, and the Gluteus maximus, from which it is separated by a
ANTERIOR FEMORAL REGION. 331
synovial bursa. By its deep surface, with the Crureus, some large branches of
the external circumflex artery and anterior crural nerve being interposed.
The Vastus interims and Crureus are so inseparably connected together, as to
form but one muscle. It is the smallest portion of the Quadriceps extensor. The
anterior portion of it, which is covered by the Rectus, being called the Crureus ;
the internal portion, which lies immediately beneath the fascia lata, is called the
Vastus Internus. It arises by an aponeurosis, which is attached to the lower part
of the line that extends from the inner side of the neck of the femur to the linea
aspera, from the whole length of the inner lip of the linea aspera, and internal
intermuscular septum. It also arises from nearly- the whole of the internal,
anterior, and external surfaces of the shaft of the femur, limited, above, by the line
between the two trochanters, and extending, below, to within the lower fourth of
the bone. From these different origins, the fibres converge to a broad aponeurosis,
which covers the anterior surface of the middle portion of the muscle (the Crureus),
and the deep surface of the inner division of the muscle (the Vastus internus) ;
becoming joined and gradually narrowing, it is inserted into the patella, blending
with the other portions of the Quadriceps extensor.
Relations. By their superficial surface, with the Psoas and Iliacus, the Rectus,
Sartorius, Pectineus, Adductors, and fascia lata, femoral vessels, and saphenous
nerve. By its deep surface, with the femur, Subcrureus, and synovial membrane
of the knee-joint.
The student will observe the striking analogy that exists between the Quadri-
ceps extensor, and the Triceps brachialis in the upper extremity. So close is this
similarity, that M. Cruveilhier has described it under the name of the Triceps
femoralis. Like the Triceps brachialis, it consists of three distinct divisions
or heads; a middle or long head, analogous to the long head of the Triceps,
attached to the ilium, and of two other portions which have respectively received
the names of the external and internal heads of the muscle. These, it will
be noticed, are strictly analogous to the outer and inner heads of the Triceps
brachialis.
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. More properly speaking, 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 this muscle. A syno-
vial bursa is interposed between the tendon and the upper part of the tuberosity
of the tibia. From the tendons corresponding to the Vasti, a fibrous prolongation
is derived, which is attached below to the upper extremities of the tibia and fibula.
It serves to protect the knee-joint, which is strengthened on its outer side by the
fascia lata.
The Subcrureus is a small muscle, usually distinct from the superficial muscle,
which arises from the anterior surface of the lower part of the shaft of the femur,
and is inserted into the upper part of the synovial pouch that extends upwards
from the knee-joint behind the patella. This fasciculus is occasionally united with
the Crureus. It sometimes consists of two separate muscular bundles.
Nerves. The Tensor vaginse femoris is supplied by the superior gluteal nerve ;
the other muscles of this region, by branches from the anterior crural.
Actions. The Tensor vaginse femoris is a tensor of the fascia lata ; continuing
its action, the oblique direction of its fibres enables it to rotate the thigh inwards.
In the erect posture, acting from below, it will serve to steady the pelvis upon the
head of the femur. The Sartorius flexes the leg upon the thigh, and, continuing
to act, the thigh upon the pelvis, at the same time drawing the limb inwards, so
as to cross one leg over the other. Taking its fixed point from the leg, it flexes
the pelvis upon the thigh, and, if one muscle acts, assists in rotating it. The
Quadriceps extensor extends the leg upon the thigh. Taking its fixed point from
the leg, as in standing, this muscle will act upon the femur, supporting it perpen-
332
MUSCLES AND FASCIJE.
dicularly upon the head of the tibia, thus maintaining the entire weight of the
body. The Eectus muscle assists the Psoas and Iliacus in supporting the pelvis
and trunk upon the femur, or in bending it forwards.
Fig. 188. — Muscles of the Internal Femoral
Region. I
Internal Femoral Region.
Gracilis.
Pectineus.
Adductor Longus.
Adductor Brevis.
Adductor Magnus.
Dissection. These muscles are at once ex-
posed by removing the fascia from the fore part
and inner side of the thigh. The limb should
be abducted, so as to render the muscles tense,
and easier of dissection.
The Gracilis is the most superficial
muscle on the inner side of the thigh. It
is thin and flattened, broad above, narrow
and tapering below. It arises by a thin
aponeurosis between two and three inches
in breadth, from the inner margin of the
ramus of the pubes and ischium. The
fibres pass vertically downwards, and
terminate in a rounded tendon which
passes behind the internal condyle of the
femur ; curving round the inner tubero-
sity of the tibia, it becomes flattened,
and is inserted into the upper part of the
inner surface of the shaft of the tibia,
below the tuberosity. The tendon of
this muscle is situated immediately above
that of the Semi-tendinosus, and beneath
the aponeurosis 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 common to it and the Semi-
tendinosus muscle.
Relations. By its superficial surface,
with the fascia lata and the Sartorius
below ; the internal saphenous vein crosses
it obliquely near its lower part, lying
superficial to the fascia lata. By its deep
surface, with the three Adductors, 'and
the internal lateral ligament of the knee-
joint.
The Pectineus 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-pectinea, from
the surface of bone in front of it, between
the pectineal eminence and spine of the
pubes, and from a tendinous prolongation
of Gimbernat's ligament, which is attached
INTERNAL FEMORAL REGION. 333
to the crest of the pubes, and is continuous with the fascia covering the outer
surface of the muscle; the fibres pass downwards, backwards, and outwards,
to be inserted into a rough line leading from the trochanter minor 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 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, upon which lies the femoral
artery. By its inner border, with the margin of the Adductor longus.
The Adductor Longus, the most superficial of the three Adductors, _ is a flat
triangular muscle, lying on the same plane as the Pectineus, with which it is often
blended above. It arises, by a flat narrow tendon, from the front of the pubes, at
the angle of junction of the crest with the symphysis ; it soon expands into a broad
fleshy belly, which, passing downwards, backwards, and outwards, is inserted, by
an aponeurosis, into the middle third of the linea aspera, between the Vastus
internus and the Adductor magnus.
Relations. By its anterior surface, with the fascia lata, and, near its insertion,
with the femoral artery and vein. By its posterior surface, with the Adductor
brevis and Adductor magnus, the anterior branches of the obturator vessels and
nerve, and with the profunda artery and vein near its insertion. By its outer
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-
wards, when the Adductor brevis and Obturator externus will be exposed.
The Adductor Brevis is situated immediately beneath the two preceding muscles.
It is somewhat triangular in form, and arises by a narrow origin from the outer
surface of the descending ramus of the pubes, between the Gracilis and Obturator
externus. Its fibres, passing backwards, outwards, and downwards, are inserted,
by an aponeurosis, into the upper part of the linea aspera, immediately behind the
Pectineus and upper part of the Adductor longus.
Relations. By its anterior surface, with the Pectineus, Adductor longus, and
anterior branches of the obturator vessels and nerve. By its posterior surface,
with the Adductor magnus, and posterior branches of the obturator vessels and
nerve. By its outer border, with the Obturator externus, and conjoined tendon
of the Psoas and Iliacus. By its inner border, with the Gracilis and Adductor
magnus. This muscle is pierced, near its insertion, by the middle perforating
branch of the profunda artery.
The Adductor brevis should now be cut away near its origin, and turned outwards, when the
entire extent of the Adductor magnus will be exposed.
The Adductor Magnus is a large triangular muscle, forming a septum between
the muscles on the inner part and those on the back of the thigh. It arises from
a small part of the descending ramus of the pubes, from the ascending ramus of
the ischium, and from the outer margin and under surface of the tuberosity of the
ischium. Those fibres which arise from the ramus of the pubes 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 ; those from the
ramus of the ischium are directed downwards and outwards with different degrees
of obliquity, to be inserted, by means of a broad aponeurosis, into the whole length
of the linea aspera and upper part of its internal bifurcation 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 tubercle above the inner condyle
of the femur, being connected by a fibrous expansion to the line leading upwards
from the tubercle to the linea aspera. Between the two portions of the muscle,
334 MUSCLES AND FASCIAE.
an angular interval is left, tendinous in front, fleshy behind, for the passage of
the femoral vessels into the popliteal space. The external portion of the muscle
is pierced by four apertures ; the three superior, for the three superior perforating
arteries, the fourth for the passage of the profunda. This muscle gives off an
aponeurosis, which passes in front of the femoral vessels, and joins with the Vastus
internus.
Relations. By its anterior surface, with the Pectineus, Adductor brevis, Adduc-
tor longus and the femoral vessels. By its posterior surface, with the great
sciatic nerve, the Gluteus maximus, Biceps, Semi-tendinosus, and Semi-membra-
nosus. By its superior or shortest border, it lies parallel with the Quadratus
femoris. 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
Adductor brevis and Adductor longus, which separate it, in front, from the Vastus
internus, and in front of the Gluteus maximus and short head of the Biceps, which
separate it from the Vastus externus.
Nerves. All the muscles of this group are supplied by the obturator nerve.
The Pectineus receives additional branches from the accessory obturator and ante-
rior crural ; and the Adductor magnus an additional branch from the great sciatic.
Actions. The Pectineus and three Adductors adduct the thigh powerfully ; they
are especially used in horse-exercise, the flanks of the horse being firmly grasped
between the knees by the action of these muscles. From their oblique insertion
into the linea aspera, they rotate the thigh outwards, assisting the external Eotators,
and when the limb has been abducted, they draw it inwards, carrying the thigh
across that of the opposite side. The Pectineus and Adductor brevis and Adduc-
tor longus assist the Psoas and Iliacus in flexing the thigh upon the pelvis. In
progression, also, all these muscles assist in drawing forwards the hinder limb.
The Gracilis assists the Sartorius in flexing the leg and drawing it inwards ; 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 the erect posture ; or, if their action is continued, to flex the pelvis
forwards upon the femur.
Gluteal Kegion-.
Gluteus Maximus. . Gemellus Superior.
Gluteus Medius. Obturator Internus.
Gluteus Minimus. Gemellus Inferior.
Pyriformis. Obturator Externus.
Quadratus Femoris.
Dissection (fig. 189). 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, the
foot inverted, and the limb abducted. An incision should be made through the integument along
the back part of the crest of the ilium and margin of the sacrum to the tip of the coccj'x, from
which point a second incision should be carried obliquely downwards and outwards to the outer
side of the thigh, four inches below the great trochanter. The portion of integument included
between these incisions, together with the superficial fascia, should be removed in the direction
shown in the figure, when the Gluteus maximus and the dense fascia covering the Gluteus medius
will be exposed.
The Gluteus Maximus, the most superficial muscle in the gluteal region, is a
very broad and thick fleshy mass, of a quadrilateral shape, which forms the pro-
minence of the nates. Its large size is one of the most characteristic points in
the muscular system in man, connected as it is with the power he has of main-
taining the trunk in the erect posture. In structure it 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 portion of bone, including the crest,
GLUTEAL KEGIOX.
335
Fig.
189. — Dissection of the Lower Ex-
tremity. Posterior View.
/ i Dissection of
CLUTEAL REGIOIJ
immediately behind it ; from the posterior surface of the last piece of the sacrum,
the side of the coccyx, and posterior surface of the great sacro-sciatic and
posterior sacro-iliac ligaments. The fibres are directed obliquely downwards and
outwards ; those forming the upper and larger
portion of the muscle (after converging some-
what) 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 lower portion of
the muscle being inserted into the rough line
leading from the great trochanter to the linea
aspera, between the Vastus externus and Ad-
ductor magnus.
Three synovial bursse are usually found se-
parating the under surface of this muscle from
the eminences which it covers. One of these,
of large size, and generally multilocular, sepa-
rates it from the great trochanter. A second,
often wanting, is situated on the tuberosity of
the ischium. A third, between the tendon of
this muscle and the Vastus externus.
Relations. By its superficial surface, with
a thin fascia, which separates it from cellular
membrane, fat, and the integument. By its
deep surface, from above downwards, 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, Semi-tendinosus, Semi-membranosus,
and Adductor magnus muscles. The gluteal
vessels and nerve are seen issuing from the
pelvis above the Pyriformis muscle, the
ischiatic and internal pudic vessels and nerves,
and the nerve to the Obturator internus
muscle below it. Its upper border is thin,
and connected with the Gluteus medius by
the fascia lata. Its lower border, free and
prominent, forms the fold of the nates, and is
directed towards the perineum.
BACK of THICB
POPLITEAL SPACE
BACK of LEG
SOLE of FOOT
Dissection. The Gluteus maxiraus should now be divided 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
should be altogether detached, and the lower portion turned outwards ; the loose areolar tissue
filling up the interspace between the trochanter major and tuberosity of the ischium being re-
moved, the parts already enumerated as exposed by the removal of this muscle will be seen.
The Gluteus Medius 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 are covered by the fascia lata, which separates it from %he
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 covering its anterior part.
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
336
MUSCLES AND FASCI.E,
Fig. 190. — Muscles of the Hip and Thigh.
TT-irm atriny
separates the tendon of the
muscle from the surface of
the trochanter in front of its
insertion.
Relations. By its superfi-
cial surface, with the Gluteus
maximus behind, the Tensor
vaginae femoris and deep fas-
cia in front. By its deep
surface, with the Gluteus mi-
nimus and the gluteal vessels
and nerve. Its anterior bor-
der is blended with the Glu-
teus minimus. Its posterior
border lies parallel with the
Pyriformis, the gluteal vessels
intervening.
This muscle should now be divided
near its insertion and turned up-
wards, when the Gluteus minimus
will be exposed.
The Gluteus Minimus, 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 con-
verge 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. A synovial
bursa is interposed between
the tendon and the great tro-
chanter.
Relations. By its superfi-
cial surface, with the Gluteus
medius, and the gluteal vessels
and nerve. By its deep sur-
face, with the ilium, the re-
flected tendon of the Eectus
femoris, and capsular liga-
ment of the hip-joint. Its
anterior margin is blended
with the Gluteus medius. Its
posterior margin is often
joined with the tendon of the
Pyriformis.
The Pyriformis is a flat
muscle, pyramidal in shape,
lying almost parallel with
GLUTEAL REGION. 337
the lower margin of the Gluteus minimus. 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, attached to the portions of bone
interposed between the second, third, and fourth anterior sacral foramina, and
also from the grooves 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, being generally
blended with the tendon of the Obturator internus.
Relations. By its anterior surface, within the pelvis, with the Rectum (especially
on the left side), the sacral plexus of nerves, and the internal iliac vessels ; external
to the pelvis, with the os innominatum and 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 nerves. By its lower border, with the
Gemellus superior ;' the ischiatic vessels and nerves, the internal pudic vessels and
nerve, and the nerve to the Obturator internus, passing from the pelvis in the
interval between them.
Dissection. The next muscle, as well as the origin of the Pyriformis, can only be seen when
the pelvis is divided, and the viscera contained in this cavity removed.
The Obturator Internus, like the preceding muscle, is situated partly within the
cavity of the pelvis, partly at the back of the hip-joint. It arises from the inner
surface of the anterior and external wall of the pelvis, being attached to the
margin of bone around the inner side of the obturator foramen ; viz., from the
descending ramus of the pubes, and the ascending ramus of the ischium ; and
laterally, from the inner surface of the body of the ischium, between the margin
of the obturator foramen in front, the great sacro-sciatic notch behind, and the
brim of the true pelvis above. It also arises from the inner surface of the obturator
membrane and from the tendinous arch which completes the canal for the passage
of the obturator vessels and nerve. The fibres are directed backwards and down-
wards, 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 covered with cartilage, grooved for their
reception, and lined with" a synovial bursa. The muscle leaves the pelvis by the
lesser sacro-sciatic notch ; and the tendinous bands unite into a single flattened
tendon, which passes horizontally outwards, and, after receiving the attachment
of the Gemelli, is inserted into the upper border of the great trochanter in front
of the Pyriformis. 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 that 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 should
be divided near its insertion and reflected outwards.
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 fasciae, 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. External to the
pelvis, it is covered by the great sciatic nerve and Gluteus maxjmus, and rests
on the back part of the hip-joint.
The Gemelli are two small muscular fasciculi, accessories to the tendon of the
Obturator internus, which is received into a groove between them. They have
received the names stqierior and inferior from the position they occupy.
The Gemellus Superior, the smaller of the two, arises from the outer surface of
the spine of the ischium, and, passing horizontally outwards, becomes blended
22
338 MUSCLES AND FASCI.E.
with the upper part of the tendon of the Obturator internus, and is inserted with
it into the upper border of the great trochanter. This muscle is sometimes
wanting.
Relations. By its superficial surface, with the Gluteus maximus and the ischiatic
vessels and nerves. By its deep surface, with the capsule of the hip-joint. By its
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 outer border of the
tuberosity of the ischium, and, passing horizontally outwards, is blended with the
lower part of the tendon of the Obturator internus, and inserted with it into the
upper border of the great trochanter.
Relations. By its superficial surface, with the Gluteus maximus, and the
ischiatic vessels and nerves. By its deep surface, it covers the capsular 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
fern oris.
The Quadratus Femoris 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 outer border of the tuberosity of the
ischium, and, proceeding horizontally outwards, is inserted into the upper part of
the linea quadrati, on the posterior surface of the trochanter major. A synovial
bursa is often found between the under surface of this muscle and the lesser tro-
chanter, which it covers.
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
externus and trochanter minor. 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 nest muscle (the Obturator externus), it is necessary to
remove the Psoas, Iliacus, Pectineus, and Adductor brevis and Adductor longus muscles, from the
front 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 examined.
The Obturator Externus is a flat triangular muscle, which covers the outer sur-
face of the anterior wall of the pelvis. It arises from the margin of bone imme-
diately around the inner side of the obturator foramen, viz., from the body and
ramus of the pubes, 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 converging pass outwards and backwards, 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
longus, Adductor brevis, and Gracilis ; and more externally, with the neck of the
femur and capsule of the hip-joint. By its posterior surface, with the obturator
membrane and Quadratus femoris.
Nerves. The Gluteus maximus is supplied by the inferior gluteal nerve and a
branch from the sacral plexus. The Gluteus medius and Gluteus minimus, by the
superior gluteal. The Pyriformis, Gemelli, Obturator internus, and Quadratus
femoris, by branches from the sacral plexus ; and the Obturator externus, by the
obturator nerve.
Actions. The Glutei muscles, Avhen they take their fixed point from the pelvis,
are all abductors of the thigh. The Gluteus maximus and the posterior fibres of
the Gluteus medius rotate the thigh outwards ; the anterior fibres of the Gluteus
medius and the Gluteus minimus rotate it inwards. The Gluteus maximus serves
to extend the femur, and the Gluteus medius and Gluteus minimus draw it forwards.
The Gluteus maximus is also a tensor of the fascia lata. Taking their fixed point
POSTERIOR FEMORAL REGION. 339
from the femur, the Glutei muscles act upon the pelvis, supporting it and the whole
trunk upon the head of the femur : this is especially obvious in standing on one
leg. In order to gain the erect posture after the effort of stooping, these muscles
draw the pelvis backwards, assisted by the Biceps, Semi-tendinosus, and Semi-
membranosus muscles. The remaining muscles are powerful rotators of the thigh
outwards. In the sitting posture, when the thigh is flexed upon the pelvis, their
action as rotators ceases, and they become abductors, with the exception of the
Obturator externus, which still rotates the femur outwards. When the femur is
fixed, the Pyriformis and Obturator muscles serve to draw the pelvis forwards if
it has been inclined backwards, and assist in steadying it upon the head of the
femur.
Posterior Femoral Region.
Biceps. Semi-tendinosus. Semi-membranosus.
Dissection (fig. 189). Make a vertical incision along the middle of the thigh, from the lower
fold of the nates 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. A third incision
should then be made 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 pop-
liteal space examined, the removal of the integument from the remaining part of the thigh
should be continued, when the fascia and muscles of this region will be exposed.
The Biceps is a large muscle, of considerable length, situated on the posterior
and outer aspect of the thigh. It arises by two heads : one, the long head, from
an impression at the upper and back part of the tuberosity of the ischium, by a
tendon common to it and the Semi-tendinosus ; the femoral or short head, from
the outer lip of the linea aspera, between the Adductor magnus and Vastus ex-
ternus, extending from two inches below the insertion of the Gluteus maximus,
to within two inches of the outer condyle ; it also arises from the external inter-
muscular septum. The fibres of the long head form a fusiform belly, which,
passing obliquely downwards and a little outwards, 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. At its insertion, the tendon
divides into two portions, which embrace the external lateral ligament of the
knee-joint, a strong prolongation being sent forwards to the outer tuberosity of
the tibia, which gives off an expansion to the fascia of the leg. The tendon of
this muscle forms the outer ham-string.
Relations. By its superficial surface, with the Gluteus maximus above, the
fascia lata and integument in the rest of its extent. By its deep surface, with the
Semi-membranosus, Adductor magnus, and Vastus externus, the great sciatic
nerve, popliteal artery and vein, and, near its insertion, with the external head of
the Gastrocnemius, Plantaris, and superior external articular artery.
The Semi-tendinosus, remarkable for the great length of its tendon, is situated
at the posterior and inner aspect of the thigh. It arises from 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 from their origin. It forms a fusiform muscle,
which, passing downwards and inwards, terminates a little below the middle of
the thigh in a long round tendon, which lies along the inner side of the popliteal
space ; curving around the inner tuberosity of the tibia, it is inserted into the
upper part of the inner surface of the shaft of that bone, nearly as far forwards
as its anterior border. This tendon lies beneath the expansion of the Sartorius,
and below that of the Gracilis, to which it is united. A tendinous intersection is
usually observed about the middle of the muscle.
Relations. By its superficial surface, with the Gluteus maximus and fascia lata.
340 MUSCLES AND FASCIAE.
By its deep surface, with the Semi-membranosus, Adductor magnus, inner head of
the Gastrocnemius, and internal lateral ligament of the knee-joint.
The Semi-membranosus, so called from the membranous expansion on its anterior
and posterior surfaces, is situated at the back part and inner side of the thigh.
It arises by a thick tendon from the upper and outer part of the tuberosity of the
ischium, above and to the outer side of the Biceps and Semi-tendinosus, and is
inserted into 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 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 this contracts into the tendon of
insertion. The tendon of the muscle at its insertion divides into three portions ;
the middle portion is the fasciculus of insertion into the back part of the inner
tuberosity, sending down an expansion to cover the Popliteus muscle. The
internal portion is horizontal, passing forwards beneath the internal lateral liga-
ment, to be inserted into a groove along the inner side of the internal tuberosity.
The posterior division passes upwards and backwards, to be inserted into the back
part of the outer condyle of the femur, forming the chief part of the posterior
ligament of the knee-joint.
The tendons of the two preceding muscles, with those of the Gracilis and
Sartorius, form the inner ham-string.
Relations. By its superficial surface, with the Semi-tendinosus, Biceps, and
fascia lata. By its deep surface, with the popliteal vessels, Adductor magnus;
and the inner head of the Gastrocnemius, from which it is separated by a synovial
bursa. By its inner border, with the Gracilis. By its outer border, with the great
sciatic nerve, and its internal popliteal branch.
Nerves. The muscles of this region are supplied by the great sciatic nerve.
Actions. The three ham-string muscles flex the leg upon the thigh. When the
knee is semi-flexed, the Biceps, from its oblique direction downwards and outwards,
rotates the leg slightly outwards ; and the Semi-membranosus, in consequence of
its oblique direction, rotates the leg inwards, assisting the Popliteus. Taking
their fixed point from below, these muscles serve to support the pelvis upon the
head of the femur, and to draw the trunk directly backwards, as is seen in feats
of strength, when the body is thrown backwards in the form of an arch.
Surgical Anatomy. The tendons of these muscles occasionally require subcutaneous division
in some forms of spurious anchylosis of the knee-joint, dependent upon permanent contraction
and rigidity of the Flexor muscles, or from stiffening of the ligamentous and other tissues sur-
rounding the joint, the result of disease. This is easily 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 towards the tendon, it should be divided, taking care that the wound in the
skin is not at the same time enlarged. This operation has been attended with considerable suc-
cess in some cases of stiffened knee from rheumatism, gradual extension being kept up for some
time after the operation.
Muscles and Fascia of the Leg.
Dissection (fig. 186). The knee should be bent, a block placed beneath it, and the foot kept
in an extended position ; an incision should then be made through the integument in the middle
line of the leg to the ankle, and continued along the dorsum of the foot to the toes. A second
incision should be made transversely across the ankle, and a third in the same direction across
the bases of the toes : the flaps of integument included between these incisions should be
removed, and the deep fascia of the leg examined.
The fascia of the leg forms a complete investment to the whole of this region
of the limb, excepting to the inner surface of the tibia, to which it is unattached.
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 Semi-tendinosus on the inner side; in front it blends with the
periosteum covering the tibia and fibula ; below, it is continuous with the annular
ligaments of the ankle. It is thick and dense in the upper and anterior part of
ANTERIOR TIBIO-FIBTJLAR REGION.
341
the leg, and gives attachment, by its inner sur-
face, to the Tibialis anticus and Extensor
longus digitorum muscles; but thinner behind,
where it covers the Gastrocnemius and Soleus
muscles. Its inner surface gives off, on the
outer side of the leg, two strong intermuscular
septa, which inclose the Peronei muscles, and
separate them from the muscles on the anterior
and posterior tibial regions, and several smaller
and more slender processes inclose the indi-
vidual muscles in each region; at the same
time, a broad transverse intermuscular septum
intervenes between the superficial and deep
muscles in the posterior tibio-fibular region.
The fascia should now be removed by dividing it in
the same direction as the integument, excepting oppo-
site the ankle, wnere it should be left entire. The re-
moval of the fascia should be commenced from below,
opposite the tendons, and detached in the line of direc-
tion of the muscular fibres.
Muscles of the Leg.
These may be subdivided into three groups :
those on the anterior, those on the posterior,
and those on the outer side.
Anterior Tibio-fibular Region.
Tibialis Anticus.
Extensor Proprius Pollicis.
Extensor Longus Digitorum.
Peroneus Tertius.
The Tibialis Anticus 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 fascia of the leg ; and
from the intermuscular septum between it and
the Extensor communis digitorum ; the fibres
pass vertically downwards, and terminate in a
tendon, which is apparent on the anterior sur-
face of the muscle at the lower third of the leg.
After passing through the innermost compart-
ment 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.
Relations. By its anterior surface, with the
deep fascia, and with the annular ligament. By
its posterior surface, with the interosseous mem-
brane, tibia, ankle-joint, and inner side of the
tarsus. By its inner surface, with the tibia.
By its outer surface, with the Extensor longus
digitorum. and Extensor proprius pollicis, the
anterior tibial vessels and nerve lying between
it and the last mentioned muscle.
•Fiff. 191. — Muscles of the Front of
" *L
\Ti6i.
^N
- A
342 MUSCLES AXD FASCIA,
_ The Extensor Proprius Pollicis is a thin, elongated, 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 the Extensor longus digitorum ; it also arises
from the interosseous membrane to a similar extent. The fibres pass downwards,
and terminate in a tendon, which occupies the anterior border of the muscle,
passes through a distinct compartment in the annular ligament, 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
its surface.
Relations. By its anterior border, with the deep fascia, and the anterior annular
ligament. By its posterior border, with the interosseous membrane, fibula, tibia,
ankle-joint, and Extensor brevis digitorum. By its outer side, with the Extensor
longus digitorum above, the dorsalis pedis vessels and anterior tibial nerve
below. By its inner side, with the Tibialis anticus, and the anterior tibial vessels
above.
The Extensor Longus Digitorum is an elongated, flattened, semi-penniform
muscle, situated the most externally of all the muscles on the fore part 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, and
deep fascia ; and from the intermuscular septa between it and the Tibialis anticus
on the inner, and the Peronei on the outer side. The muscle terminates in three
tendons, which pass through a canal in the annular ligament, with the Peroneus
tertius, run across the dorsum of the foot, and, the innermost tendon having sub-
divided into two, 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
tendon opposite the metatarso-phalangeal articulation is joined, on its outer side,
by the tendon of the Extensor brevis digitorum (except the fourth), and receives
a fibrous expansion from the Interossei and Lumbricales, which then spreads
into a broad aponeurosis, covering 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 onwards, to be inserted into the base of the third.
Relations. By its anterior surface, with the deep fascia, and the annular liga-
ment. By its posterior surface, with the fibula, interosseous membrane, ankle-
joint, and Extensor brevis digitorum. By its inner side, with the Tibialis anticus,
Extensor proprius pollicis, and anterior tibial vessels and nerve. By its outer side,
with the Peroneus longus and Peroneus brevis.
The Peroneus Tertius may be considered as part of the Extensor longus digi-
torum, being almost always intimately united with it. It arises from the lower
fourth of the anterior surface of the fibula, on its outer side ; from the lower part
of the interosseous membrane ; and from an intermuscular septum between it and
the Peroneus brevis. Its tendon, after passing through the same canal in the
annular ligament as the Extensor longus digitorum, is inserted into the base of the
metatarsal bone of the little toe, on its dorsal surface. This muscle is sometimes
wanting.
Nerves. These muscles are supplied by the anterior tibial nerve.
Actions. The Tibialis anticus and Peroneus tertius are the direct flexors of the
tarsus upon the leg ; the former muscle, from the obliquity in the direction of its
tendon, raises the inner border of the foot, and the latter, acting with the Peroneus
brevis and Peroneus longus, will draw the outer border of the foot upwards, and
the sole outwards. The Extensor longus digitorum and Extensor proprius pollicis
extend the phalanges of the toes, and, continuing their action, flex the tarsus upon
the leg. Taking their origin from below, in the erect posture, all these muscles
serve to fix the bones of the leg in a perpendicular direction, and give increased
strength to the ankle-joint.
POSTERIOR TIBIO-FIBULAR REGION.
343
Fig. 192.
-Muscles of the Back of the Leg.
Superficial Layer.
Posterior Tibio-fibular Region.
Dissection (fig. 189). 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
what is called "the calf of the leg. Its
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 pro-
gression.
Superficial Layer.
Gastrocnemius. Soleus.
Plantaris.
The Gastrocnemius is the most super-
ficial 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
head, the larger, and a little the most
posterior, is attached to a depression at
the upper and back part of the inner
condyle; the outer head, to the upper
and back part of the external condyle,
immediately above the origin of the
Popliteus. Both heads, also, arise by a
few tendinous and fleshy fibres from the
ridges which are continued upwards from
the condyles to the linea aspera. Each
tendon spreads into an aponeurosis, which
covers the posterior surface of that por-
tion of the muscle to which it belongs ;
that covering the inner head being longer
and thicker than the outer. From the
anterior surface of these tendinous ex-
pansions, muscular fibres are given off;
those in the median line, which cor-
respond 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 the posterior
surface of an aponeurosis which covers
the front of the muscle, and this, gradu-
ally 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 sepa-
rates it from the external saphenous vein
and nerve. By its deep surface, with the
344 MUSCLES AND FASCIA.
posterior 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 downwards, in
order to expose the next muscles.
The Soleus is a broad flat muscle, situated immediately beneath the preceding.
It has received its name from the fancied resemblance it bears to a sole-fish. It
arises by tendinous fibres from the back part of the head, and from the upper
half of the posterior surface of the shaft of the fibula, from the oblique line of
the tibia, and from the middle third of its internal border ; some fibres also arise
from a tendinous arch placed between the tibial and fibular origins of the muscle,
and beneath which the posterior tibial vessels and nerve pass into the leg. The
fibres pass backwards 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 forms with it the tendo Achillis.
delations. By its superficial surface, with the Gastrocnemius and Plantaris. By
its deep surface, with the Flexor longus digitorum, Flexor longus pollicis, Tibialis
posticus, and posterior tibial vessels and nerve, from which it is separated by the
transverse intermuscular septum.
The tendo Achillis, the common tendon of the Gastrocnemius and Soleus, is
the thickest and strongest tendon in the body. It is about six inches in length,
and formed by the junction of the aponeuroses of the two preceding muscles. It
commences about the middle of the leg, but receives fleshy fibres on its anterior
surface, nearly to its lower end. Gradually becoming contracted below, it is
inserted into the lower part of the posterior tuberosity of the os calcis, a synovial
bursa being interposed between the tendon and the upper part of the tuberosity.
The tendon is covered by the fascia and the integument, and 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 saphe-
nous vein.
The Plantaris is an extremely diminutive muscle, placed between the Gastroc-
nemius and Soleus, and remarkable for its long and delicate tendon. It arises
from the lower part of the outer bifurcation of the linea aspera, and from the
posterior ligament of "the knee-joint. It forms a small fusiform belly, about two
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. At times, its tendon
is lost in the internal annular ligament, or in the fascia of the leg.
Nerves. These muscles are supplied by the internal popliteal nerve.
Actions. The muscles of the calf possess considerable power, and are con-
stantly called into use in standing, walking, dancing, and leaping ; hence the large
size they usually present. 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 forwards.
In standing, the Soleus, taking its fixed point from below, steadies the leg upon
the foot, and prevents the body from falling forwards, 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 serves as a tensor of the plantar fascia.
POSTERIOR TIBIO-FIBULAR REGION.
345
Posterior Tibio-fibular region.
Popliteus.
Flexor Longus Pollicis.
Dissection. Detach the Soleus from its attachment
downwards, when the deep layer of muscles
exposed, covered by the deep fascia of the leg
Deep Layer.
Flexor Longus Digitorum.
Tibialis Posticus.
to the fibula and tibia, and turn It
The deep fascia of the leg is a broad,
transverse, intermuscular septum, inter-
posed between the superficial and deep
muscles in the posterior tibio-fibular re-
gion. On each 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 Semi-membranosus; it
is thinner in the middle of the leg, but,
below, where it covers the tendons passing
behind the malleoli, it is thickened. It
is continued onwards in the interval
between the ankle and the heel, where it
covers the vessels, and is blended with
the internal annular ligament.
This fascia should now be removed, commenc-
ing from below opposite the tendons, and detach-
ing it from the muscles in the direction of their
fibres.
The Popliteus is a thin, flat, triangular
muscle, which forms the floor of the
popliteal space, and is covered by a
tendinous expansion, derived from the
Semi-membranosus muscle. It arises by
a strong flat 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; and 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 sur-
face of the muscle. The tendon of the
muscle is covered by that of the Biceps
and the external lateral ligament of the
knee-joint; it grooves the outer surface
of the external semilunar cartilage, and
is invested by the synovial membrane of
the knee-joint.
Relations. By its superficial surface,
with the fascia above mentioned, which
separates , it from the Gastrocnemius,
Plantaris, popliteal vessels, and internal
popliteal nerve. By its deep surface, with
the superior tibio-fibular articulation, and
back of the tibia.
Fig.
193. — Muscles of the Back of the Leg.
Deep Layers.
346 MUSCLES AND FASCIA.
The Flexor Longus Pollicis 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 internal surface of the shaft of the fibula, with the exception of an
inch below ; from the lower part of the interosseous membrane ; from an inter-
muscular septum between it and the Peronei, externally ; and from the fascia
covering the Tibialis posticus. The fibres pass obliquely downwards and back-
wards, and terminate round a tendon which occupies nearly the whole length of
the posterior surface of the muscle. This tendon passes through a groove on the
posterior surface of the tibia, external to that for the Tibialis posticus and Flexor
longus digitorum ; it then passes through another groove on the posterior extremity
of the astragalus, and along a third groove, beneath the tubercle of the os calcis,
into the sole of the foot, where it runs forwards between the two heads of the
Flexor brevis pollicis, and is inserted into the base of the last phalanx of the great
toe. 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 fascia. By its deep surface, with the fibula,
Tibialis posticus, the peroneal vessels, the lower part of the interosseous mem-
brane, and the ankle-joint. By its outer border, with the Peronei. By its inner
border, with the Tibialis posticus, and Flexor longus digitorum.
The Flexor Longus Digitorum 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 intermuscular septum,
between it and 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 inner 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, forwards and outwards, beneath the arch of the os calcis, into the
sole of the foot, where, crossing beneath the tendon of the Flexor longus pollicis,
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 in-
serted into the bases of the last phalanges of the four lesser toes, each tendon pass-
ing through a fissure in the tendon of the Flexor brevis digitorum, opposite the
middle of the first phalanges.
Relations. In the leg. By its superficial surface, with the Soleus, and the pos-
terior vessels and nerve, from which it is separated by the deep fascia. By
its deep surface, with the tibia and Tibialis posticus. In the foot, it is covered by
the Abductor pollicis, and Flexor brevis digitorum, and crosses beneath the
Flexor longus pollicis.
The Tibialis Posticus lies between the two preceding muscles, and is the most
deeply seated of all the muscles in the leg. It commences above, by two pointed
processes, separated by an angular interval, through which the anterior tibial
vessels pass forwards to the front of the leg. It arises from the posterior surface of
the interosseous membrane, its whole length, excepting its lowest part, from the
posterior surface of the shaft of the tibia, external to the Flexor longus digitorum,
between the commencement of the oblique line above, and the middle of the
external border of the bone below, and from the upper two-thirds of the inner
surface of the shaft of the'fibula ; some fibres also arise from the deep 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, terminates in a tendon, which passes through a groove with it
behind the inner malleolus, but inclosed in a separate sheath, then passes through
FIBULAR REGIOX. 347
another sheath, over the internal lateral ligament, and beneath the calcaneo-
scaphoid articulation, and is inserted into the tuberosity of the scaphoid, and
internal cuneiform bones. The tendon of this muscle contains a sesamoid bone,
near its insertion, and gives off fibrous expansions, one of which passes back-
wards to the os calcis, some outwards to the middle and external cuneiform, and
others forwards to the bases of the third and fourth metatarsal bones.
Relations. By its superficial surface, with the Soleus and Flexor longus
digitorum, the posterior tibial vessels and nerve, and the peroneal vessels, from
which it is separated by the deep fascia. By its deep surface, with the interosseous
ligament, the tibia, fibula, and ankle-joint.
Nerves. The Popliteus is supplied by the internal popliteal nerve, the remaining
muscles of this group by the posterior tibial nerve.
Actions. The Popliteus assists in flexing the leg upon the thigh ; when the leg
is flexed, it may rotate the tibia inwards. The Tibialis posticus is a direct extensor
of the tarsus upon the leg ; acting in conjunction with the Tibialis anticus, it
turns the sole of the foot inwards, antagonizing the Peroneus longus which
turns it outwards. The Flexor longus digitorum and Flexor longus pollicis 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 extensor, the toes would be drawn inwards,
were it not for the Flexor accessorius muscle, which is inserted into the outer side
of that 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.
I
Fibulae Region.
Peroneus Longus. Peroneus Brevis.
Dissection. These muscles are readily exposed, by removing the fascia covering their surface,
from below upwards, in the line of direction of their fibres.
The Peroneus 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 from the head and
upper two-thirds of the outer surface of the shaft of the fibula, from the deep
fascia, and from the intermuscular septa between it and the muscles on the front,
and those on the back of the leg. It terminates in a long tendon, which passes
behind the outer malleolus, in a groove, common to it and the Peroneus brevis,
the groove being converted into a canal by a fibrous band, and the tendons
invested by a common synovial membrane ; it is then reflected, obliquely forwards,
across the outer side of the os calcis, being contained in a separate fibrous sheath,
lined by a prolongation of the synovial membrane, from the groove behind
the malleolus. Having reached the outer side of the cuboid bone, it runs, in a
groove, on its under surface, which is converted into a canal by the long calcaneo-
cuboid ligament, lined by a synovial membrane, and crossing, obliquely, the sole
of the foot, is inserted into the outer side of the base of the metatarsal bone of
the great toe. The tendon of the muscle has a double reflection, 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 bone is
usually developed in its substance.
Relations. By its superficial surface, with the fascia and integument. By its
deep surface, with the fibula, the Peroneus brevis, os calcis, and cuboid bone.
By its anterior border, an intermuscular septum intervenes between it and the
Extensor longus digitorum. By its posterior border, an intermuscular septum
separates it from the Soleus above, and the Flexor longus pollicis below.
348 MUSCLES AND FASCIA.
The Peroneus Brevis lies beneath the Peroneus longus, and is shorter and
smaller than it. It arises from the middle third of the external surface of the
shaft of the fibula, internal to the Peroneus longus ; from the anterior and posterior
borders of the bone ; and from the intermuscular septa separating it from the
adjacent muscles on the front and back part of the leg. The fibres pass vertically
downwards, and terminate in a tendon, which runs through the same groove as
the preceding muscle, 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, and is finally inserted into the base of the meta-
tarsal bone of the little toe, on its dorsal surface.
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 Peroneus brevis are supplied by the musculo-
cutaneous branch of the external popliteal nerve.
Actions. The Peroneus longus and Peroneus brevis extend the foot upon the leg,
in conjunction with the Tibialis posticus, antagonizing the Tibialis anticus and Pero-
neus tertius, which are flexors of the foot. The Peroneus longus also everts the sole
of the foot ; hence the extreme e version observed in fracture of the lower end of
the fibula, where that bone offers no resistance to the action of this muscle.
Taking their fixed point below, they serve to steady the leg upon the foot. This
is especially the case in standing upon one leg, when the tendency of the superin-
cumbent weight is to throw the leg inwards ; and the Peroneus longus overcomes
this 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 bloodvessels, and especially
their action upon the foot, as their rigidity and contraction give rise to one or the other forms
of deformity known as club-foot. The most simple and common deformity, and one that is rarely
if ever congenital, is the talipes equinus, the heel being raised by rigidity and contraction of the
Gastrocnemius muscle, and the patient walking upon the ball of the foot. In the talipes varus,
which is the more common congenital form, the heel is raised by the tendo Achillis, the inner
border of the foot drawn upwards by the Tibialis anticus, and the anterior two-thirds of the foot
twisted inwards by the Tibialis posticus and Flexor longus digitorum, the patient walking upon
the outer edge of the foot, and in severe cases upon the dorsum and outer ankle. 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. Each of these deformities may be successfully relieved (after other remedies fail) by
division of the opposing tendons and fascia; by this means, the foot regains its proper position,
and the tendons heal by the organization of lymph thrown out between the divided ends. 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 between it and the skin.
Muscles and Fasciae of the Foot.
The fibrous bands 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, the anterior, internal, and external.
The Anterior Annular Ligament consists of a superior or vertical portion,
which binds down the Extensor tendons as they descend on the front of the tibia
and fibula, and an inferior or horizontal portion, which retains them in connection
with the tarsus, the two portions being connected by a thin intervening layer of
fascia. The vertical portion is attached externally to the lower end of the fibula,
internally to the tibia, and above is continuous with the fascia of the leg ; it
contains two separate sheaths, one internally for the tendon of the Tibialis anti-
OF THE FOOT. 349
eus ; one externally, for the tendons of the Extensor longus digitorum and Pero-
neus tertius, and the tendon of the Extensor proprius pollicis, and the anterior tibial
vessels and nerve pass beneath it. The horizontal portion is attached externally
to the upper surface of the os calcis, in front of the depression for the interosseous
ligament, and internally to the inner malleolus and plantar fascia : it contains
three sheaths, the most internal for the tendon of the Tibialis anticus, the next
in order for the tendon of the Extensor proprius pollicis, and the most external for
the Extensor communis digitorum and Peroneus tertius : the anterior tibial ves-
sels and nerve lie altogether beneath it. These sheaths are lined by separate
synovial membranes.
The Internal Annular Ligament 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 bony grooves in this situation into osteo-fibrous canals, for the passage
of the tendons of the Flexor muscles and vessels into the sole of the foot. It is
continuous above with the deep fascia of the leg, below with the plantar fascia
and the fibres of origin of the Abductor pollicis muscle. The three canals which
it forms transmit from within outwards, first, the tendon of the Tibialis posticus ;
secondly, the tendon of the Flexor longus digitorum, then the posterior tibial 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 pollicis.
Each of these canals is lined by a separate synovial membrane.
The External Annular Ligament extends from the extremity of the outer
malleolus to the outer surface of the os calcis, and binds down the tendons of the
Peronei muscles in their passage beneath the outer ankle. The two tendons are
inclosed in one synovial sac.
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 ; it should then be
removed from the fascia in a direction from behind forwards, as seen in fig. 189.
The Plantar Fascia, the densest of all the fibrous membranes, is of great
strength, and consists of dense pearly -white glistening fibres, disposed, for the
most part, longitudinally ; it is divided into a central and two lateral portions.
The central portion, the thickest, is narrow behind and attached to the inner
tuberosity of the os calcis, behind the origin of the Flexor brevis digitorum, and,
becoming broader and thinner in front, divides opposite the middle of the meta-
tarsal bones into five processes, one for each of the toes. Each of these processes
divides opposite the metatarso-phalangeal articulation into two slips, which em-
brace the sides of the Flexor tendons of the toes, and are inserted into the sides
of the metatarsal bones, and into 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 and Interossei 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 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 upwards 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 attach-
ment behind to the Flexor brevis digitorum muscle.
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
350 MUSCLES AND FASCIAE.
thick behind, thin in front, and extends from the os calcis forwards to the base of
the fifth metatarsal bone, into the outer side of which it is attached ; it is con-
tinuous 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 pollicis muscle ; it is
attached behind to the internal annular ligament, is continuous around the side
of the foot with the dorsal fascia, and externally with the middle portion of the
plantar fascia.
Muscles of the Foot.
These are divided into two groups : 1. Those on the dorsum ; 2. Those on the
plantar surface.
1. Dorsal Kegiost.
Extensor Brevis Digitorum.
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 on
the dorsum of the foot. On the removal of this fascia, the muscles of the dorsal
region of the foot are exposed.
The Extensor Brevis Digitorum is a broad thin muscle, which arises from the
outer side of the os calcis, in front of the groove for the Peroneus brevis ; from
the astragalo-calcanean ligament ; and from the horizontal portion of the anterior
annular ligament ; passing obliquely across the dorsum of the foot, it terminates
in four tendons. The innermost, which is the largest, is inserted into the first
phalanx of the great toe ; the other three, into the outer sides of the long Extensor
tendons of the second, third, and fourth toes.
delations. By its superficial surface, with the fascia of the foot, the tendons of
the Extensor longus digitorum, and Extensor proprius pollicis. By its deep sur-
face, with the tarsal and metatarsal 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.
2. Plantar Eegion. *
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. In order to
facilitate the dissection of these muscles, it will be found more convenient to divide
them into three layers, as they present themselves, in the order in which they are
successively exposed.
First Layer.
Abductor Pollicis. 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 backwards. The central portion should be divided transversely
in the middle of the foot, and the two flaps dissected forwards and backwards.
OF TIIE SOLE OF THE FOOT. FIRST LAYER.
351
The Abductor Pollicis lies along the inner border of the foot. It arises from
the inner tuberosity 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 pollicis, 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
surface, with the Flexor brevis polli-
Fig. 194.— Muscles of the Sole of the Foot.
First Layer.
cis, the Flexor accessorius, and the
tendons of the Flexor longus digitorum
and Flexor longus pollicis, the Tibialis
anticus and posticus, the plantar ves-
sels and nerves, and the articulations
of the tarsus.
The Flexor Brevis Digitorum lies
in the middle line of the sole of the
foot, immediately beneath the plantar
fascia, with which it is firmly united.
It arises, by a narrow tendinous pro-
cess, from the inner tuberosity of the
os calcis ; from the central part of the
plantar fascia ; and from the intermus-
cular septa between it and the adjacent
muscles. It passes forwards, and
divides into four tendons. Opposite
the middle of the first phalanges, each
tendon presents a longitudinal slit, to
allow of the passage of the correspond-
ing tendon of the Flexor longus digi-
torum, the two portions forming a
groove for its reception, and, after re-
uniting, divides a second time into two
processes, which are inserted into
the sides of the second phalanges.
The mode of division of the tendons
of the Flexor brevis digitorum, and
of their insertion into the phalanges, is
analogous to that of the Flexor sublimis
in the hand.
Relations. By its superficial surface,
with the plantar fascia. By its deep
surface, with the Flexor accessorius,
the Lumbricales, the tendons of the
Flexor longus digitorum, and the ex-
ternal 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 prolongations of
the plantar fascia.
The Abductor Minimi Digiti lies along the outer border of the foot. It arises.
by a very broad origin, from the outer tuberosity of the os calcis, from the under
surface of the% os calcis in front of both tubercles, from the plantar fascia, and the
intermuscular 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 the little toe.
352
MUSCLES AND FASCIAE.
Relations. By its superficial surface, with, the plantar fascia. By its deep
surface, with the Flexor accessorius, the Flexor brevis minimi digiti, the long
plantar ligament, and Peroneus longus. On its inner side are the external plantar
vessels and nerve, and it is separated from the Flexor brevis digitorum by a ver-
tical septum of fascia.
Dissection. The muscles of the superficial layer should be divided at their origin, by inserting
the knife beneath each, and cutting obliquely backwards, so as to detach them from the bone ;
. they should then be drawn forwards, in order
Fig. 195.— Muscles of the Sole of the Foot.
Second Layer.
to expose the second layer, but not separated
at their insertion. The two layers are sepa-
rated by a thin membrane, the deep plantar
fascia, on the removal of which are seen the
tendon of the Flexor longus digitorum, with
its accessory muscle, the Flexor longus pol-
licis, and the Lumbricales. The long flexor
tendons cross each other at an acute angle,
the Flexor longus pollicis running along the
inner side of the foot, on a plane superior to
that of the Flexor longus digitorum. the di-
rection of which is obliquely outwards.
Second Layer.
Flexor Accessorius.
Lumbricales.
The Flexor Accessorius arises by two
heads : the inner or larger, which is
muscular, being attached to the inner
concave surface of the os calcis, and
to the calcaneo- scaphoid ligament; the
outer head, flat and tendinous, to the
under surface of the os calcis, in front
of its outer tuberosity, and to the long
plantar ligament. The two portions
become united at an acute angle, and
are inserted into the outer margin and
upper and under surfaces of the tendon
of the Flexor longus digitorum, form-
ing a kind of groove, in which the
tendon is lodged.
Relations. By its superficial surf ace,
with the muscles of the superficial
layer, from which it is separated by
the external 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 forwards on the inner side of each of the lesser toes, and is
inserted into the expansion of the long Extensor and base of the second 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 forwards, in order to expose the third layer.
OF THE SOLE OF THE FOOT— THIRD LAYER.
353
Third Layer.
Flexor Brevis Pollicis.
Adductor Pollicis.
Flexor Brevis Minimi Digiti.
Transversus Pedis.
Fig. 196.— Muscles of the Sole of the Foot.
Third Layer.
The Flexor Brevis Pollicis arises, by a pointed tendinous process, from the
inner border 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 head of
this muscle is blended with the Ab-
ductor pollicis previous to its insertion ;
the outer head, with the Adductor
pollicis; and the tendon of the Flexor
longus pollicis lies in a groove between
them.
Relations. By its superficial surface,
with the Abductor pollicis, the tendon
of the Flexor longus pollicis and plantar
fascia. 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 pollicis.
By its outer border, with the Adductor
pollicis.
The Adductor Pollicis is a large, thick,
fleshy mass, passing obliquely across
the foot, and occupying the hollow space
between the four outer metatarsal 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, and is inserted,
together with the outer head of the
Flexor brevis, pollicis, into the outer
side of the base of the first phalanx of
the great toe.
The Flexor Brevis Minimi Digiti lies
on the metatarsal bone of the little toe.
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.
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 Transversus Pedis is a narrow, flat, muscular fasciculus, stretched trans-
versely across the heads of the metatarsal bones, between them and the flexor
tendons. It arises from the under surface of the head of the fifth metatarsal
bone, 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 pollicis.
23
554
SURGICAL ANATOMY.
Relations. By its under surface, with the tendons of the long and short
Flexors and Lumbricales. By its upper surface, with the Interossei.
Fig. 197. — The Dorsal Interossei.
Left Foot.
Fig. 19S.— The Plantar Interossei.
Left Foot.
The Interossei.
The Interossei muscles in the foot are simi-
lar to those in the hand. They are seven in
number, and consist of two groups, dorsal, and
plantar.
The Dorsal Interossei, 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
being inserted into, the bases of the first pha-
langes, and into the aponeurosis of the common
Extensor tendon. In the angular interval left
between 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. They
are all abductors from an imaginary line or
axis drawn through the second toe.
The Plantar Interossei, 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 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. These muscles are all
adductors towards an imaginary line, extend-
ing through the second toe.
Nerves. The internal plantar nerve supplies
the Abductor pollicis, Flexor brevis digitorum,
Flexor brevis pollicis, and the first and second
Lumbricales. The external plantar nerve sup-
plies the Abductor minimi digiti, Flexor
accessorius, third and fourth Lumbricales, Ad-
ductor pollicis, Flexor brevis minimi digiti,
Transversus pedis, and all the Interossei.
SURGICAL ANATOMY.
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 fracture may be especially selected for
illustration and description.
OF THE MUSCLES OF THE LOWER EXTREMITY.
355
Fracture of the neck of
the femur within the cap-
sular ligament (fig. 199)
is a very common accident,
and is most frequently
caused by indirect vio-
lence, such as slipping off
the edge of the curbstone,
the impetus and weight
of the body falling upon
the neck of the bone. It
usually occurs in females,
and seldom under fifty
years of age. At this
period of life, the cancel-
lous tissue of the neck of
the bone not unfrequently
is atrophied, becoming soft
and infiltrated with fatty
matter, and the compact tis-
sue is partially absorbed ;
hence the bone is more
brittle, and more liable to
fracture. The characteris-
tic marks of this accident
are slight shortening of the
limb, and eversion of
the foot, neither of which
symptoms occur, however,
in some cases until some
time after the injury. The
eversion is caused by the combined action of the external
rotator muscles, as well as by the Psoas and Iliacus, Pec-
tineus, Adductors, and Glutei muscles. The shortening
and retraction is produced by the action of the Glutei, and
by the Rectus femoris in front, and the Biceps, Semi-tendi-
nosus, and Semi-membranosus behind.
Fracture of the femur just below the trochanters (fig. 200)
is an accident of not unfrequent occurrence, and is at-
tended with great displacement producing considerable
deformity. The upper fragment, the portion chiefly dis-
placed, is tilted forwards almost at right angles with the
pelvis, by the combined action of the Psoas and Iliacus ;
and, at the same time, everted and drawn outwards 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, from the lower fragment being
drawn upwards by the Rectus in front, and the Biceps,
Semi-membranosus, and Semi-tendinosus behind ; and, at
the same time, everted, and the upper end thrown out-
wards, the lower inwards, by the Pectineus and Adductor
muscles. This fracture may be reduced in two different
methods; either by direct relaxation of all the opposing
muscles, to effect which, the limb should be placed on a
double inclined plane; or, by overcoming the contraction
of the muscle by continued extension, which may be
effected by means of the long splint.
Oblique fracture of the femur immediately above the con-
dyles (fig. 201) 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 backwards by the Gastrocnemius,
SSoleus, and Plantaris muscles ; and upwards by the poste-
rior femoral, and Rectus muscles. The pointed end of the
upper fragment is drawn inwards by the Pectineus and
Adductor muscles, and tilted forwards by the Psoas and
Biacus, 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
Fig. 199. — Fracture of the Neck of the Femur within the
Capsular Ligament.
PTRiro«MI j
CCMCI.LUS SHrnitn
OBTURATOR
■TURATOM CXTERNUI
UAORATWS FCKORif
Fig. 200. — Fracture of the Femur
below the Trochanters.
rtMI-MCMI.ARV
I1MI- II HOIK.
35 C
SURGICAL ANATOMY.
care is requisite in keeping the pointed extremity of the upper fragment in proper apposition ;
otherwise, after union of the fracture, extension of the limb is partially destroyed from the Kec-
tus muscle being held down by the fractured end of the bone, and from the patella, when elevated,
being drawn upwards against it.
Fig. 201. — Fracture of the Femur above the Condyles.
Fig. 202.— Fracture of the Patella.
Fig. 203.
-Oblique Fracture of the Shaft
of the Tibia.
Fracture of the patella (fig. 202) may be produced by muscular action, or by direct violence.
When produced by muscular action, it occurs thus : a person in danger of falling forwards,
attempts to recover himself by throwing the body backwards, and the violent action of the
Quadriceps extensor upon the patella snaps
that bone transversely across. The upper frag-
ment is drawn up the thigh by the Quadriceps
extensor, the lower fragment being retained in
its position by the ligamentum patellae ; the
extent of separation of the two fragments de-
pending upon the degree of laceration of the
ligamentous structures around the bone. The
patient is totally unable to straighten the
limb, the prominence of the patella is lost,
and a marked but varying interval can be felt
between the fragments. The treatment consists
in relaxing the opposing muscles, which maybe
effected by raising the trunk, and slightly elevat-
ing the limb, which should be kept in a straight
position. Union is usually ligamentous. In
fracture from direct violence, the bone is gene-
rally comminuted, or fractured obliquely or per-
pendicularly.
Oblique fracture of the shaft of the tibia
(fig. 203) usually occurs at the lower fourth of
the bone, this being the narrowest and weakest
part, and is usually accompanied with fracture
of the fibula. If the fracture has taken place
obliquely from above, downwards and forwards.
the fragments ride over one another, the lower
fragment being drawn backwards and upwards
by the powerful action of the muscles of the calf;
the pointed extremity of the upper fragment
projects forwards immediately beneath the in-
tegument, often protruding through it, and ren-
dering the fracture a compound one. If the
direction of the fracture is the reverse of that
shown in the figure, the pointed extremity of the
lower fragment projects forwards, riding upon
the lower end of the upper one. By bending the
knee, which relaxes the opposing muscles, and
OF THE MUSCLES OF THE LOWER EXTREMITY
357
making extension from the knee and ankle, the fragments may be brought into apposition. It
is often necessary, however, in compound fracture, to remove a portion of the projecting bone
with the saw before complete adapta-
tion can be effected. Fig. 204.— Fracture of the Fibula, with Displacement
Fracture of the fibula, with displace- of the Tibia. — " Pott's Fracture. "
merit of the tibia (fig. 204), commonly
known as " Pott's Fracture," is one of
the most frequent injuries of the ankle-
joint. The end of the tibia is displaced
from the corresponding surface of the
astragalus, the internal lateral ligament
is ruptured, and the iiiner malleolus
projects inwards beneath the integu-
ment, which is tightly stretched over
it, and in danger of bursting. The
fibula is broken, usually from two to
three inches above the ankle, and oc-
casionally that portion of the tibia
with which it is more directly connected
below; the foot is everted by the action
of the Peroneus longus, its inner border
resting upon the ground, and, at the
same time, the heel is drawn up by the
muscles of the calf. This injury may
be at once reduced by flexing the leg
at right angles with the thigh, which
relaxes all the opposing muscles, and
by making slight extension from the
knee and ankle.
For a detailed account of the Minute Anatomy of Muscle, reference should be made to the
following sources of information : Quain's " Elements of Anatomy." — Kolliker's " Handbook of
Human Microscopic Anatomy," before alluded to. — Todd' and Bowman's " Physiological Ana-
tomy."— To the article, " Muscle and Muscular Motion," by W. Bowman, in the Cyclopedia of
Anatomy ; and " On the Minute Structure of Voluntary Muscle," by the same author, in the
Phil. Trans. 1840, 1841.
On the Descriptive Anatomy of the Muscles, refer to Cruveilhier's "Anatomie Descriptive." —
"Traite de Myologie et d'Angeiologie," by F. G. Theile, " 1'ncyclopedie Anatomique," Paris, 1843 ;
and Henle's "Handbuch der Systematischen Anatomic," before alluded to.
Of 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 (<% trjnv, to contain air), 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, contained blood in
the living body.
The pulmonary artery, which arises from the right ventricle of the heart, carries
venous blood directly into the lungs, from whence it is returned by the pulmonary
veins into the left auricle. This constitutes the lesser or pulmonic circulation.
The great artery, the aorta, which arises from the left ventricle, conveys arterial
blood to the body generally ; from whence it is brought back to the right side of
the heart by means of the veins. This constitutes the greater or systemic cir-
culation.
The distribution of the systemic arteries is like a highly ramified tree, the com-
mon 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
animal body, with the exception of the hairs, nails, epidermis, cartilages, and
cornea ; and the larger trunks usually occupy the most protected situations, run-
ning, in the limbs, 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 cceliac and thyroid axes ; or the vessel may give off several branches
in succession, and still continue as the main trunk, as is seen in the arteries of the
limbs ; 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, arise from the aorta at an obtuse angle ; others, as the lumbar
arteries, at a right angle ; or, as the spermatic, at an acute angle. An artery from
which a branch is given off* is smaller in size, but 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 com-
bined 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 freely with one another, forming
what is called an anastomosis (avo, between ; ar6fia, mouth), or inosculation ; and this
communication is very free between the large, as well as between the smaller
branches. The anastomoses between trunks of equal size is found where great
freedom and activity of the circulation is requisite, as in the brain ; here, the two
vertebral arteries unite to form the basilar, and the two internal carotid arteries are
connected by a short inter-communicating trunk ; it is also found in the abdomen,
the intestinal arteries having very free anastomoses between their larger branches.
In the limbs, the anastomoses are most frequent and of largest size around the
joints ; the branches of an artery above, freely inosculating with branches from
the vessel below. These anastomoses are of considerable interest to the surgeon,
as it is by their enlargement that a collateral circulation 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
358
GENERAL ANATOMY. 359
twigs, these inosculations become so numerous as to constitute a close network
that pervades nearly every tissue of the body.
Throughout the body generally, the larger arterial branches pursue a perfectly
straight course, but in certain situations they are tortuous : thus, the facial artery
in its course over the face, and the labial arteries of the lips, are extremely tor-
tuous in their course, to accommodate themselves to the movements of these parts.
The uterine arteries are also tortuous, to accommodate themselves to the increase
of size which this organ undergoes during pregnancy. Again, the internal carotid
and vertebral arteries, previous to their entering the cavity of the skull, describe
a series of curves, which are evidently intended to diminish the velocity of the
current of blood, by increasing the extent of surface over which it moves, and
adding to the amount of impediment which is produced from friction.
The arteries are dense in structure, of considerable strength, highly elastic, and,
when divided, they preserve, although empty, 'their cylindrical form.
The arteries are composed of three coats — internal, middle, and external.
The internal, the thinnest, consists usually of two layers, an inner or epithelial, and
an outer or elastic coat. The former consists of a single layer of fusiform-shaped
epithelial cells with round or oval nuclei. The latter is a transparent, colorless,
shining membrane, perforated with small elongated apertures (hence the name,
fenestrated), and marked with numerous reticulations. This layer is perfectly
smooth when the artery is distended ; but when empty presents numerous longi-
tudinal and transverse folds.
In arteries above the size of the capillaries, the elastic layer is very delicate,
and the epithelium clearly demonstrable.
In arteries of less than a line in diameter, the internal coat consists of two layers,
as above described ; but in medium-sized arteries, several lamellae, composed of
elastic fibres and connective tissue, are interposed between the epithelial and elastic
coats. In the largest arteries, the inner coat is usually much thickened, especially
in the aorta ; and consists of a homogeneous substance, occasionally striated or
fibrillated, traversed by longitudinal elastic networks, which are very fine in the
lamellae immediately beneath the epithelium, but increase in thickness from within
outwards. The internal and middle coats are separated, by either a dense elastic
reticulated coat or a true fenestrated membrane.
The middle coat, thicker than the preceding, consists of muscular and elastic
fibres, and connective tissue, disposed chiefly in the transverse direction. In the
largest arteries, this coat is of great thickness, of a yellow color, and highly
elastic ; it diminishes in thickness, and becomes redder in color as the arteries
become smaller, becomes very thin, and finally disappears. In small arteries, this
coat is purely muscular, consisting of muscular fibre-cells united to form lamellae,
which vary in number according to the size of the arteries, the very small arteries
having only a single layer, and those not larger than the T'0th of a line three or
four layers. In arteries of medium size, this coat becomes thicker in proportion
with the size of the vessel ; its layers of muscular tissue are more numerous, and
intermixed with numerous fine elastic fibres which unite to form broad-meshed
networks. In the larger vessels of this class, as the femoral, superior mesenteric,
coeliac, external iliac, brachial, and popliteal arteries, the elastic fibres unite to form
lamellae, which alternate with the layers of muscular fibre. In the largest arteries,
the muscular tissue is only slightly developed, and forms about one-third or one-
fourth of the whole substance of the middle coat. This is especially the case in the
aorta, and trunk of the pulmonary artery, in which the individual cells of the
muscular layer are imperfectly formed ; while, in the carotid, axillary, iliac, and
subclavian arteries, the muscular tissue of the middle coat is more developed.
The elastic lamellae are well marked, may amount to fifty or sixty in number, and
alternate regularly with the layers of muscular fibre. They are most distinct, and
arranged with most regularity, in the abdominal aorta, innominate artery, and
common carotid.
The external, or areolar and elastic coat, the thickest of the three, consists of
360 ARTERIES.
connective tissue and elastic fibres. It is very thin in the largest arteries ; hut in
those of medium size, and in small arteries, is as thick as, or thicker than the middle
coat. In small arteries, this coat consists of connective tissue and fine elastic fibres.
In arteries rather larger than the capillaries, the elastic fibres are wanting ; the
connective tissue composing the coat becoming, the nearer it approaches the capil-
laries, more homogeneous, being gradually reduced to a thin membranous envelope
which finally disappears. In articles of medium size, this coat is composed of
two distinct layers, an inner composed of elastic tissue ; an outer, composed of
connective tissue, containing elastic networks irregularly connected with each
other. The inner elastic layer is very distinct in the carotid, femoral, brachial,
profunda, mesenteric, and cceliac arteries, the elastic fibres being often arranged
in lamellae. . .
Some arteries have extremely thin coats in proportion to their size ; this is
especially the case in those situated in the cavity of the cranium and spinal canal,
the difference depending upon the greater thinness of the external and middle
coats.
The arteries, in their distribution throughout the body, are included in a thin
areolo-fibrous investment, which forms what is called their sheath. In the limbs,
this is usually formed by a prolongation of the deep fascia ; in the upper part of
the thigh, it consists of a continuation downwards of the transversalis and iliac
fasciae of the abdomen ; in the neck, of a prolongation of the deep cervical fascia.
The included vessel is loosely connected with its sheath by a delicate areolar
tissue, and the sheath usually incloses the accompanying veins, and sometimes a
nerve. Some arteries, as those in the cranium, are not included in sheaths.
All the larger arteries are supplied with bloodvessels like the other organs of
the body ; they are called vasa vasorum. These nutrient vessels arise from a
branch of the artery or from a neighboring vessel, at some considerable distance
from the point at which they are distributed ; they ramify in the loose areolar
tissue connecting the artery with its sheath, and are distributed to the external
and middle coats, and, according to Arnold and others, supply the internal coat.
Minute veins serve to return the blood from these vessels ; they empty themselves
into the venae comites in connection with the artery. Arteries are also provided
with nerves ; they are derived chiefly from the sympathetic, but partly from the
cerebro-spinal system. They form intricate plexuses upon the surface of the larger
trunks, the smaller branches being usually accompanied by single filaments ; their
exact mode of distribution is unknown. According to Kolliker, the majority of
the arteries of the brain and spinal cord, those of the choroid, of the placenta, as well
as many arteries of muscles, glands, and membranes, are unprovided with them.
The smaller arterial branches, excepting those of the cavernous structures of
the sexual organs, and in the uterine placenta, terminate in a network of vessels
which pervade nearly every tissue of the body. These vessels, from their minute
size, are termed capillaries {capillus, " a hair"). They are interposed between the
smallest branches of the arteries and the commencing veins, constituting a net-
work, the branches of which maintain the same diameter throughout, the meshes
of the network being more uniform in shape and size than those formed by the
anastomoses of the small arteries and veins.
The diameter of the capillaries varies in the different tissues of the body, their
usual size being about ^Vtrth part of an inch. The smallest are those of the
brain, and the mucous membrane of the intestines ; the largest, those of the skin,
and the marrow of bones.
The form of the capillary net varies in the different tissues, being modifications
chiefly of rounded or elongated meshes. The rounded form of mesh is most
common, and prevails where there is a dense network, as in the lungs, in most
glands and mucous membranes, and in the cutis ; the meshes being more or less
angular, sometimes nearly quadrangular, or polygonal ; more frequently, irregular.
Elongated meshes are observed in the bundles of fibres and tubes composing
muscles and nerves, the meshes being usually of a parallelogram form, the long
GENERAL ANATOMY. 361
axis of the mesh running parallel with the long axis of the nerve or fibre. Some-
times the capillaries have a looped arrangement, a single vessel projecting from
the common network, and returning after forming one or more loops, as in the
papillae of the tongue and skin.
The number of the capillaries, and the size of the meshes, determine the degree
of vascularity of a part. The closest network, and the smallest interspaces, are
found in the lungs and in the choroid coat of the eye. In the liver and lung, the
interspaces are smaller than the capillary vessels themselves. In the kidney, in
the conjunctiva, and in the cutis, the interspaces are from three to four times as
large as the capillaries which form them ; and from eight to ten times as large as
the capillaries of the brain in their long diameter, and from four to six times as
large in their transverse diameter. In the cellular coat of the arteries, the width.
of the meshes is ten times that of the capillary vessels. As a general rule, the
more active the function of an organ is, the closer is its capillary net, and the
larger its supply of blood ; the network being very narrow in all growing parts,
in the glands, and in the mucous membranes ; wider in bones and ligaments, which
are comparatively inactive ; and nearly altogether absent in tendons and cartilages,
in which very little organic change occurs after their formation.
Structure. The walls of the capillaries consist of a fine, transparent, homoge-
neous membrane, in which are imbedded, at intervals, minute oval corpuscles,
probably the remains of the nuclei of the cells from which the vessel was origi-
nally formed. The largest capillaries have a trace of an epithelial lining, and a
few filaments circularly dispersed.
In the description of the arteries, we shall first consider the efferent trunk of
the systemic circulation, the aorta, and its branches ; and then the efferent trunk
of the pulmonic circulation, the pulmonary artery.
The Aorta.
The aorta (aoprr;, arteria magna) is the main trunk of a series of vessels, which,
arising from the heart, conveys the red oxygenated blood to every part of the
body for its nutrition. This vessel commences at the upper part of the left ven-
tricle, and, after ascending for a short distance, arches backwards to the left side,
over the root of the left lung, descends within the thorax on the left side of the
vertebral column, passes through the aortic opening in the Diaphragm, and enter-
ing the abdominal cavity terminates, considerably diminished in size, opposite
the fourth lumbar vertebra, where it divides into the right and left common iliac
arteries. Ilence its subdivision into the arch of the aorta, the thoracic aorta and
the abdominal aorta, from the direction or position peculiar to each part.
Arch of the Aorta.
Dif section. In order to examine the arch of the aorta, the thorax should be opened, by divid-
ing the cartilages of the ribs on each side of the sternum, and raising this bone from below up-
wards, and then sawing through the sternum on a level with its articulation with the clavicle.
By this means, the relations of the large vessels to the upper border of the sternum and root of
the neck are kept in view.
The arch of the aorta extends from the origin of the vessel at the upper part
of the left ventricle, to the lower border of the body of the third dorsal vertebra.
At its commencement, it ascends behind the sternum, obliquely upwards and
forwards towards the right side, and opposite the upper border of the second
costal cartilage of the right side, passes transversely from right to left, and from
before backwards to the left side of the second dorsal vertebra ; it then descends
upon the left side of the body of the third dorsal vertebra, at the lower border of
which it becomes the thoracic aorta. Hence this portion of the vessel is divided
into an ascending, a transverse, and a descending portion. The artery in its course
describes a curve, the convexity of which is directed upwards and to the right
side, the concavity in the opposite direction.
362
ARTERIES.
Ascending Part of the Arch.
The ascending portion of the arch of the aorta is about two inches in length.
It commences at the upper part of the left ventricle, in front of the left auriculo-
ventricular orifice, and opposite the middle of the sternum on a line with its
junction to the third costal cartilage ; it passes obliquely upwards in the direction
of the heart's axis, to the right side, as high as the upper border of the second
costal cartilage, describing a slight curve in its course, and being situated, when
SfVagu.
Reeurrmt laryngeal
Fig. 205. — The Arch of the Aorta and its Branches.
I
Left Vagus
Left Phrenic
— ThoracicDuct
Fig. 206. Flan rftluBranJm
Itfl Crmmrj
distended, about a quarter of an inch behind the posterior surface of the sternum.
A little above its commencement, it is somewhat enlarged, and presents three small
dilatations, called the sinuses of the aorta (sinuses of Valsalva) opposite to which
are attached the three semilunar valves, which serve the purpose of preventing
any regurgitation of blood into the cavity of the ventricle. A section of the aorta
opposite this part has a somewhat triangular figure ; but below the attachment of
the valves it is circular. This portion of the arch 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.
ARCH OF AORTA. 363
Relations. The ascending part of the arch is covered at its commencement by
the trunk of the pulmonary artery and the right auricular appendage, and, higher
up, is separated from the sternum by the pericardium, some loose areolar tissue,
and the remains of the thymus gland ; behind, it rests upon the right pulmonary
vessels and root of the right lung. On the right side, it is in relation with the
superior vena cava and right auricle ; on the left side, with the pulmonary artery.
Plan of the Relations of the Ascending Pakt of the Arch.
In front.
Pulmonary artery.
, Eight auricular appendage.
Pericardium.
Remains of thymus gland.
Right side. f \ heft side.
Superior vena cava. ( ^orta f * Pulmonary artery.
Eight auricle.
Behind.
Right pulmonary vessels.
Eoot of right lung.
Transverse Part of the Arch.
The second or transverse portion of the arch commences at the upper border of
the second costo-sternal articulation of the right side in front, and passes from
right to left, and from before backwards, to the left side of the second dorsal
vertebra behind. Its upper border is usually about an inch below the upper
margin of the sternum.
Relations. Its anterior surface is covered by the left pleura and lung, and
crossed towards the left side by the left pneumogastric and phrenic nerves, and
cardiac branches of the sympathetic. Its posterior surface lies on the trachea,
just above its bifurcation, on the great 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
carotid, and left subclavian arteries. By its lower border, with the bifurcation of
the pulmonary artery, and the remains of the ductus arteriosus, which is connected
with the left division of that vessel ; the left recurrent laryngeal nerve winds
round it from before backwards, whilst the left bronchus passes below it.
Plan of the Relations of the Transverse Part of the Arch.
Above.
Left innominate vein.
Arteria innominata.
Left carotid.
Left subclavian.
In front. ^ ^ Behind.
Left pleura and lung. / \^ Trachea.
Left pneumogastric nerve- / ^rtof \ Cardiac plexus.
Left phrenic nerve. I Transverse (Esophagus.
Cardiac nerves. V Portion. / Thoracic duct.
Left recurrent nerve.
lii'lnw.
Bifurcation of pulmonary artery.
Eemains of ductus arteriosus.
Left recurrent nerve.
Left bronchus.
364 ARTERIES.
Descending Part of the Arch.
The descending portion of the arch, has a straight direction, inclining downwards
on the left side of the body of the third dorsal vertebra, at the lower border of
which it becomes the thoracic aorta.
Relations. Its anterior surface is covered by the pleura and root of the left
lung ; behind, it lies on the left side of the body of the third dorsal vertebra. On
its right side lie the oesophagus and thoracic duct ; on its left side it is covered
by the pleura.
Plan of the Relations of the Descending Part of the Arch.
In front.
Pleura.
Hoot of left lung.
Right side. /r X £e/if s^e-
(Esophagus. / AAr«rhtiiof \ Pleura.
Thoracic duct.
Behind.
Left side of body of third dorsal vertebra.
The ascending, transverse, and descending portions of the arch vary in position
according to the movements of respiration, being lowered, together with the
trachea, bronchi, and pulmonary vessels, during inspiration by the descent of the
Diaphragm, and elevated during expiration, when the Diaphragm ascends. These
movements are greater in the ascending than the transverse, and in the latter
than the descending part.
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 three inches, below this point.
Direction. Sometimes the aorta arches over the root of the right instead of the left lung, as
in birds, and passes down on the right side of the spine. In such cases, all 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 pecu-
liarity not being accompanied by any transposition of the viscera.
Conformation. The aorta occasionally divides into an ascending and a descending trunk, as
in some quadrupeds, the former, directed vertically upwards, subdividing 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 their division ; 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 part of the arch is contained in the pericardium, just
behind the sternum, its commencement being crossed by the pulmonary artery and right auricular
appendage, having the root of the right lung 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 aortic sinuses, in the great majority
of cases affects the right coronary sinus : this is mainly owing to the regurgitation of blood upon
the sinuses, taking place chiefly on the right anterior aspect of the vessel. As the aneurismal
sac enlarges, it may compress any or all of the structures in immediate proximity with it, but
chiefly projects towards 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 bursts
in the cavity of the pericardium, the patient suddenly drops down dead, and, upon a post-mortem
examination, the pericardial hag 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 it may compress the superior cava.
Aneurism of the ascending aorta, originating above the sinuses, most frermently implicates
the right anterior wall of the vessel ; this is probably mainly owing to the blood being impelled
ARCH OF AORTA. 365
against this part. The direction of the aneurism is also chiefly towards the right of the median
line. If it attains a large size and projects forwards, it may absorb the sternum and the carti-
lages 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 even
open into the right lung, the trachea, bronchi, or oesophagus.
Regarding the transverse part of the arch, 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. Now an aneurismal tumor taking origin from the posterior part or right
aspect of the vessel, its most usual site, may press upon the trachea, 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 symp-
toms 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 this tube, when fatal hemorrhage will occur. Again, the
innominate artery, or the left carotid, or subclavian, 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 the tumor may
present itself at or above the manubrium, generally either in the median line, or to the right of
the sternum.
Aneurism affecting the descending part of the arch is usually directed backwards and to the
left side, causing absorption of the vertebras and corresponding ribs ; or it may press upon the
trachea, left bronchus, oesophagus, and the right and left lungs, generally the latter. When rup-
ture of the sac occurs, this usually takes place into the left pleural cavity ; less frequently into
the left bronchus, the right pleura, or into the substance of the lungs or trachea. In this form
of aneurism, pain is almost a constant and characteristic symptom, existing either in the back or
chest, and usually radiating from the spine around the left side. This symptom depends upon
the aneurismal sac compressing the intercostal nerves against the bone.
Branches of the Arch of the Aorta (figs. 205 and 206).
The branches given off from the arch of the aorta are five in number. Two
of small size from the ascending portion, the right and left coronary ; and three of
large size from the transverse portion, the innominate artery, the left carotid, and
the left subclavian.
Peculiarities. Position of the Branches. The branches, instead of arising from the highest
part of the arch (their usual position), may be moved more to the right, arising from the com-
mencement 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 towards the innominate artery.
The Number of the primary branches may be reduced to two : the left carotid arising from the
innominate artery, or (more rarely) the carotid and subclavian arteries of the left side arising
from a left 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 arose from the left end of the arch ; in other cases, it
was the second or third branch given off instead of the first. Lastly, the number of trunks
from the arch may be increased to five or six ; in these instances, the external and internal caro-
tids arose separately from the arch, the common carotid being absent on one or both sides.
Usual Number, but 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 supplying 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 two 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.
Secondary Branches sometimes arise from the arch ; most commonly it is the left vertebral,
which usually takes origin between the left carotid and left subclavian, or beyond them. Some-
times a thyroid branch is derived from the arch, or the right internal mammary, or left vertebral,
or, more rarely, both vertebrals.
The Coronary Arteries.
The coronary arteries supply the heart ; they are two in number, right and left,
arising near the commencement of the aorta immediately above the free margin
of the semilunar valves.
The Bight Coronary Artery, about the size of a crow's quill, arises from the
aorta immediately above the free margin of the right semilunar valve,, between
366 ARTERIES.
the pulmonary artery and the appendix of the right auricle. It passes forwards
to the right side in the groove between the right auricle and ventricle, and, curving
around the right border of the heart, runs along its posterior surface as far as the
posterior interventricular groove, where it divides into two branches, one of which
continues onward in the groove between the left auricle and ventricle, and anas-
tomoses with the left coronary; the other descends along the posterior inter-
ventricular furrow, supplying branches to both ventricles, and to the septum,
anastomosing at the apex of the heart with the descending branch of the left
coronary.
This vessel sends a large branch along the thin margin of the right ventricle to
the apex, and numerous small branches to the right auricle and ventricle, and
commencement of the pulmonary artery.
The Left Coronary, smaller than the former, arises immediately above the free
edge of the left semilunar valve, a little higher than the right ; it passes forwards
between the pulmonary artery and the left appendix auriculas, and descends
obliquely towards the anterior interventricular groove, where it divides into two
branches. Of these, one passes transversely outwards in the left auriculo-ventri-
cular groove, and winds around the left border of the heart to its posterior surface,
where it anastomoses with the superior branch of the right coronary ; the other
descends along the anterior interventricular groove to the apex of the heart,
where it anastomoses with the descending branch of the right coronary. The left
coronary supplies the left auricle and its appendix, both ventricles, and numerous
small branches to the pulmonary artery, and commencement of the aorta.
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 addi-
tional branches.
Aeteeia Innominata.
The innominate artery is the largest branch given off from the arch of the aorta.
It arises from the commencement of the transverse portion in front of the left
carotid, and, ascending obliquely to the upper border of the right sterno-clavicular
articulation, divides into the right carotid and 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 bone of the sternum by the
Sterno-hyoid and Sterno-thyroid muscles, the remains of the thymus gland, and
by the left innominate and right inferior thyroid veins which cross its root. Behind,
it lies upon the trachea which it crosses obliquely. On the right side are the right
vena innominata, right pneumogastric nerve, and the pleura ; and on the left side,
the remains of the thymus gland, and origin of the left carotid artery.
Plan of the Relations of the Innominate Aeteey.
In front.
Sternum.
Sterno-hyoid and Sterno-thyroid muscles.
Remains of thymus gland.
Left innominate and right inferior thyroid veins.
Right side. Left side.
Right vena innominata. / ^\ Remains of thymus.
Right pneumogastric nerve. f \ Left carotid.
Pleura.
Behind.
Trachea.
Pecidiarities 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
INNOMINATE; COMMON CAROTID. 367
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
considerable interest for the surgeon to remember in connection with the operation of including
this vessel in a ligature.
Branches. The arteria innominata occasionally supplies a thyroid branch, the middle thyroid
artery, which ascends along the front of the trachea to the thyroid gland ; and sometimes, a
thymic or bronchial branch. The left carotid is frequently joined with the innominate artery at
its origin. Sometimes, there is no innominate artery, the right subclavian arising directly from
the arch of the aorta.
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.
Surgical Anatomy. Although the operation of tying the innominate artery has been per-
formed by several surgeons, for aneurism of the right subclavian extending inwards as far as the
Scalenus, in no instance has it been attended with success. An important fact has, however,
been established, viz., that the circulation in the parts supplied by the artery can be supported
after the operation ; a fact which cannot but encourage surgeons to have recourse to it whenever
the urgency of the case may require it, notwithstanding that it must be regarded as peculiarly
hazardous.
The failure of the operation in those cases where it has been performed has depended on sub-
sequent repeated secondary hemorrhage, or on inflammation of the adjoining pleural sac and
lung. The main obstacles to its performance are,^is the student will perceive from his dissection
of this vessel, its deep situation 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 placed upon his back, with the
shoulders raised, and the head bent a little backwards, so as to draw out the artery from behind
the sternum into the neck. An incision two inches long is then made along the anterior border
of the Sterno-mastoid muscle, terminating at the sternal end of the clavicle. From this point, a
second incision is to be carried about the same length along the upper border of the clavicle.
The skin is to be dissected back, and the Platysma being exposed must be 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 must be divided
transversely throughout the greater part of its attachment. 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 now come into view, and must be carefully drawn either upwards or downwards, by
means of a blunt hook. On no account should these vessels be divided, as it would add much to
the difficulty of the operation, and endanger its ultimate success. After tearing through a strong
fibro-cellular lamina, the right carotid is brought into view, and being traced downwards, the
arteria innominata is arrived at. The left vena innominata should now be depressed, the right
vena innominata, the internal jugular vein, and pneumogastric 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 upwards and inwards ; 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 a coagulum.
It has been seen that the failure of this operation depends either upon repeated secondary
hemorrhage, or inflammation of the pleural sac and lung. The importance of avoiding the
thyroid plexus of veins during the primary steps of the operation, and the pleural sac whilst
including the vessel in the ligature, should be most carefully attended to.
Common Carotid Arteries.
The common carotid arteries, although occupying a nearly similar position in
the neck, differ in position, and, consequently, in their relations at their origin.
The right carotid arises from the arteria innominata, behind the right sterno-
clavicular articulation ; the left from the highest part of the arch of the aorta.
The left carotid is, consequently, longer and placed more deeply in the thorax. It
will, therefore, be more convenient to describe first 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 (see fig. 205).
The left carotid within the thorax passes obliquely outwards 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 innominate
vein, and the remains of the thymus gland ; behind, it lies on the trachea, ceso-
368 ARTERIES.
phagus, and thoracic duct. Internally, it is in relation with the arteria innominata ;
externally, with the left pneumogastric nerve, and left subclavian artery.
Plan of the Relations of the Left Common Carotid ;
Thoracic Portion.
In front.
Sternum.
Sternohyoid and Sternothyroid muscles.
Left innominate vein.
Remains of thymus gland.
Internally. .. . Externally.
Arteria innominata. f f M \^ Left pneumogastric nerve.
Left subclavian artery.
Behind.
Trachea.
(Esophagus.
Thoracic duct.
In the neck, the two common carotids resemble each other so closely, that one
description will apply to both. Starting from each side of the neck, each vessel
passes obliquely upwards, from behind the sterno-clavicular articulation, to a level
with the upper border of the thyroid cartilage, where it divides into the external
and internal carotid ; these names being derived, the former from its distribution
to the external parts of the head and face, the latter from its distribution to the
internal parts of the cranium. The course of the vessel is indicated 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.
At the lower part of the neck the two common carotid arteries are separated
from each other by a very small interval, which corresponds to the trachea ; but
at the upper part, the thyroid body, the larynx and pharynx project forwards
between these vessels, and give the appearance of their being placed further back
in this situation. The common carotid artery is contained in a sheath, derived
from the deep cervical fascia, which also incloses the internal jugular vein and
pneumogastric 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 structures are seen to be separated from one another, each
being inclosed 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 superficial fascia, Platysma, and deep fascia, the
Sterno-mastoid, Sterno-hyoid, and Sterno-thyroid muscles, and by the Omo-hyoid
opposite the cricoid cartilage ; but in the upper part of its course, near its ter-
mination, it is more superficial, being covered merely by the integument, the
superficial fascia, Platysma, and deep fascia, and inner margin of the Sterno-
mastoid, and is 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
outwards by the sterno-mastoid artery ; it is also crossed by the facial, lingual,
and superior thyroid veins, which terminate in the internal jugular, and, descending
on its sheath in front, is seen the descendens noni nerve, this filament being joined
with branches from the cervical nerves, which cross the vessel from without
inwards. Sometimes the descendens noni is contained within the sheath. The
middle thyroid vein crosses it about its centre, and the anterior jugular vein below.
Behind, the artery lies in front of the cervical portion of the spine, resting first
COMMON CAROTID.
369
on the Longus colli muscle, then on the Rectus anticus major, from which it is
separated by the sympathetic nerve. 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 inferior thyroid artery and
recurrent laryngeal nerve being interposed; higher up, with the larynx and
Fig. 207. — Surgical Anatomy of the Arteries of the Neck. Right Side.
Fie. 208.
Pin n of tit
JZrunclu* ~.^
cfllx \
JXTfRNAL CAROTID
pharynx. On its otiter side are placed the internal jugular vein and pneumogas-
trie nerve.
At the lower part of the neck, the internal jugular vein on the right side
recedes from the artery, but on the left side it approaches it, and often crosses 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.
24
370 ARTERIES.
Plan of the Relations of the Common Carotid Artery.
In front.
Integument and fascia. Omo-hyoid.
Platysma. Descendens noni nerve.
Sterno-mastoid. Sterno-mastoid artery.
Sterno-hyoid. Thyroid, lingual, and facial veins.
Sterno-thyroid. Anterior jugular vein.
Externally. ^ — -^ Internally.
Internal jugular vein. / \ Trachea.
Pneumogastric nerve. ( Common \ Thyroid gland.
Recurrent laryngeal nerve.
Inferior thyroid artery.
Larynx.
Pharynx.
Behind.
Longus colli. Sympathetic nerve.
Rectus anticus major. Inferior thyroid artery.
Recurrent laryngeal nerve.
Peculiarities as to Origin. The right common carotid may arise above or below its usual
point (the upper border of the sterno-clavicular articulation). This variation occurs in one out
of about eight cases and a half, and is more frequently above than below the point stated ; or its
origin may be transferred to the arch of the aorta, or it may arise in conjunction with the left
carotid. The left common carotid varies more frequently in its origin than the right. In the
majority of cases it arises with the innominate artery, or, where the innominate artery was ab-
sent, the two carotids arose usually by a eingle trunk. This vessel has a tendency towards the
right side of the arch, occasionally being the first branch given off from the transverse portion.
It rarely joins with the left subclavian, except in cases of transposition of the arch.
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 cases, this occurs higher than
usual, the artery dividing into two branches opposite the hyoidbone, or even higher ; more rarely,
it occurs below its usual place, opposite the middle of the larynx, or the lower border of the cri-
coid cartilage ; and one case is related by Morgagni, where this vessel, 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 two 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 one subject, on one side in another.
Occasional Branches. The common carotid usually gives off no branches, but it occasionally
gives origin to the superior thyroid, or a laryngeal branch, the inferior thyroid, or, more rarely,
the vertebral artery.
Surgical Anatomy. The operation of tying the common carotid artery may be necessary in
a wound of that vessel or its branches, in an 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 above and below the wounded part. If. however, one of the branches of that vessel is
wounded, or has an aneurismal tumor connected with it, a ligature maybe applied to any part of
it, excepting its origin and termination. 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 a ligature
should be placed, 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 of the jugular vein, in the great ma-
jority of cases, passes obliquely in front of it. Neither should the upper end be selected, for here
the superior thyroid, lingual, and facial veins would give rise to very considerable difficulty in the
application of a ligature. The point most favorable for the operation is opposite the lower part
of the larynx, and here a ligature may be applied on the vessel, either above or below the point
where it is crossed by the Omo-hyoid muscle. In the former situation the artery is most acces-
sible, and it may be tied there in cases of wounds, or aneurism of any of the large branches of the
carotid; whilst in cases of aneurism of the upper part of the carotid, that part of the vessel may
be selected which is below the Omo-hyoid. It occasionally happens that the carotid artery bifur-
cates 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.
EXTERNAL CAROTID 371
In this operation, the direction of the vessel and the inner margin of the Sterno-mastoid are the
chief guides to its performance.
To tie the Common Carotid, above the Omo-hyoid. The patient should be placed on his back
with the head thrown back ; an incision is to be made, three inches long, in the direction of the
anterior border of the Sterno-mastoid, from a little below the angle of the jaw to a level with
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 forwards so as to relax the parts some-
what, and the margins of the wound must be held asunder by copper spatulae. The descendens
noni nerve is now exposed, and must be avoided, and the sheath of the vessel having been raised
by forceps is to be opened over the artery to a small extent. The internal jugular vein will now
present itself alternately distended and relaxed; this should be compressed both above and below,
and drawn outwards, in order to facilitate the operation. The aneurism needle is now passed
from the outside, care being taken to keep the needle in those contact with tile artery, and thus
avoid the risk of injuring the jugular vein, or including the vagus nerve. Be/ore the ligature is
secured, it should be ascertained that nothing but the artery is included in it.
To tie the Common Carotid, below the Omo-hyoid. The patient should be placed in the same
situation as above mentioned. An incision about three inches in length is to be made, parallel
with the inner edge of the Sterno-mastoid, commencing on a level with the cricoid cartilage.
The inner border of the Sterno-mastoid having been exposed, the sterno-mastoid artery and a
large vein, the middle thyroid, will be seen, and must be carefully avoided ; the Sterno-mastoid is
to be drawn outwards, and the Sterno-hyoid and Sterno-thyroid muscles inwards. The deep fascia
must now be divided below the Omo-hyoid muscle, and the sheath, having been exposed, must be
opened, care being taken to avoid the descendens noni, which here runs on the inner or tracheal
side. The jugular vein and vagus nerve being then pressed to the outer side, the needle must
be passed round the artery from without inwards, great care being taken to avoid the inferior
thyroid artery, and the recurrent laryngeal and sympathetic nerves which lie behind it.
Collateral Circulation. After ligation 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 and inferior thyroid arteries,
and the profunda cervicis, and arteria princeps cervicis of the occipital ; the vertebral taking the
place of the internal carotid within the cranium.
External Carotid Artery.
The external carotid artery (fig. 207) arises opposite the upper border of the
thyroid cartilage, and, taking a slightly curved course, ascends upwards and for-
wards, and then inclines backwards, to the space between the neck of the condyle
of the lower jaw and the external meatus, where it divides into the temporal
and internal maxillary arteries. It rapidly diminishes in size as it ascends 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
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 con-
tained in the triangular space bounded by the Sterno-mastoid behind, the Omo-
hyoid below, and the posterior belly of the Digastric and Stylo-hyoid above ; it
is covered by the skin, Platysma, deep fascia, and anterior margin of the Sterno-
mastoid, crossed by the hypoglossal nerve, and by the lingual and facial veins ;
it is afterwards crossed by the Digastric and Stylo-hyoid muscles, and higher
up passes deeply into the substance of the parotid gland, where it lies be-
neath the facial nerve, and the junction of the temporal and internal maxillary
veins.
Internally are the hyoid bone, the wall of the pharynx, and the ramus of the
jaw, from which it is separated by a portion of the parotid gland.
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.
372 ARTERIES.
Plan of the Relations of the External Carotid.
Infront. Behind.
Integument, superficial fascia. ^—~ ^ Superior laryngeal nerve.
Platysma and deep fascia. f ^\ Stylo-glossus.
Hypoglossal nerve. / \ Stylo-pharyngeus.
Lingual and facial veins. I camid! I Glosso-pharyngeal nerve.
Digastric and Stylo-hyoid muscles. V J Parotid gland.
Facial nerve and parotid gland. V /
Temporal and maxillary veins. ^- ^
Internally.
Hyoid bone.
Pharynx.
Parotid gland.
Eamus of jaw.
Surgical Anatomy. The application of a ligature to the external carotid may be required in
cases of wounds of this vessel, or of its branches when these cannot be tied ; this, however, is
an operation very rarely performed, ligation of the common carotid being preferable, on account
of the number of branches given off from the external. To tie this vessel 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 cricoid cartilage,
as in the operation for tying the common carotid. To tie the vessel above the Digastric, be-
tween 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 successively the skin, Platysma. and fascia. By separating
the posterior belly of the Digastric and Stylo-hyoid muscles, which are seen at the lower part
of the wound, from the parotid gland, the vessel will be exposed, and a ligature may be applied
to it.
Branches. The external carotid artery gives off eight branches, which, for
convenience of description, may be divided into four sets. (See Plan of the
Branches, fig. 208.)
Anterior. Posterior. Ascending. . Terminal.
Superior thyroid. Occipital. Ascending pha- Temporal.
Lingual. Posterior auricular. ryngeal. Internal maxillary.
Facial.
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 (figs. 207 and 212) is the first branch given
off from the external carotid, being derived from that vessel just below the greater
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 trian-
gular space bounded by the Sterno-mastoid, Digastric, and Omo-hyoid muscles.
After ascending upwards and inwards for a short distance, it curves downwards
and forwards 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 distributes numerous branches to its anterior surface, anastomosing with its
fellow of the opposite side, and with the inferior thyroid arteries. Besides the
arteries distributed to the muscles and substance of the gland, its branches are
the following : —
Hyoid. Superior laryngeal.
Superficial descending branch. Crico-thyroid.
The hyoid is a small branch which runs along the lower border of the os
hyoides, beneath the Thyro-hyoid muscle ; after supplying the muscles connected
to that bone, it forms an arch, by anastomosing with the vessels of the opposite
side.
The superficial descending branch runs downwards and outwards across the
sheath of the common carotid artery, and supplies the Sterno-mastoid and neigh-
boring muscles and integument. It is of importance that the situation of this
vessel be remembered, in the operation for tying the common carotid artery.
SUPERIOR THYROID; LINGUAL. 373
The superior laryngeal, larger than either of the preceding, accompanies the
superior laryngeal nerve, beneath the Thyro-hyoid muscle ; it pierces the thyro-
hyoid membrane, and supplies the muscles, mucous membrane, and glands of the
larynx and epiglottis, anastomosing with the branch from the opposite side.
The crico-thyroid (inferior laryngeal) is a small branch which runs transversely
across the crico-thyroid membrane, communicating with the artery of the oppo-
site side. The position of this vessel should be remembered, as it may prove the
source of troublesome hemorrhage during the operation of laryngotomy.
Surgical Anatomy. The superior thyroid, or some of its branches, is occasionally 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 performed, 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, in bronchocele, has been performed in numerous instances with partial or temporary suc-
cess. When, however, the collateral circulation between this vessel and the artery of the oppo-
site side, and the inferior thyroid, is completely re-established, the tumor usually regains its
former size.
The Lingual Artery (fig. 212) arises from the external carotid between the
superior thyroid and facial ; it runs obliquely upwards and inwards to the great
cornu of the hyoid bone, then passes horizontally forwards parallel with the great
cornu, and, ascending perpendicularly to the under surface of the tongue, turns
forwards on its under surface as far as the tip of that organ, under the name of
the ranine artery.
Relations. Its first, or oblique portion, is superficial, being contained in the
triangular intermuscular space already described, resting upon the Middle con-
strictor of the pharynx, and covered by the Platysma and fascia of the neck. Its
second or horizontal portion also lies upon the Middle constrictor, being covered
at first by the tendon of the Digastric, and the Stylo-hyoid muscle, and afterwards
by the Hyo-glossus, the latter muscle separating it from the hypoglossal nerve.
Its third or ascending 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 lies nearly parallel with the lingual
artery, separated from it, in the second part of its course, by the Hyo-glossus
muscle.
The branches of the lingual artery are the
Hyoid. Sublingual.
Dorsalis linguae. Ranine.
The hyoid branch 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 linguse (fig. 212) arises from the lingual artery beneath the Hyo-
glossus muscle ; ascending to the dorsum of the tongue, it supplies its mucous
membrane, the tonsil, soft palate, and epiglottis, and anastomoses with its fellow
from the opposite side.
The sublingual, a branch of bifurcation of the lingual artery, arises at the ante-
rior margin of the Hyo-glossus muscle, and, running forwards and outwards
beneath the Mylo-hyoid to the sublingual gland, supplies its substance, giving
branches to the Mylo-hyoid and neighboring muscles, the mucous membrane of
the mouth and gums.
The ranine may be regarded as the continuation of the lingual artery ; it runs
along the under surface of the tongue, resting on the Lingualis, and covered by
the mucous membrane of the mouth ; it lies on the outer side of the Genio-hyo-
glossus, and is covered by the Hyo-glossus and Stylo-glossus, accompanied by
the gustatory nerve. On arriving at the tip of the tongue, it anastomoses with
374
the artery of the opposite side,
each side of the fraenum.
ARTERIES.
These vessels in the mouth are placed one on
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
vessel at once secured. In the latter case, it has been suggested that the lingual artery should
be tied near its origin. If the student, however, will observe the depth at which this vessel is
placed from the surface, the number of important parts which surround it on every side, and
its occasional irregularity of origin, the great difficulty of such an operation will be apparent;
under such circumstances, it is more advisable that the external or common carotid should be
tied.
Troublesome hemorrhage may occur in the division of the fraenum in children, if the ranine
artery, which lies on each side of it, is cut through. The' student should remember that the
operation is always to be performed with a pair of blunt-pointed scissors, which should be so
'held as to divide the part in the direction downwards and backwards ; the ranine artery and
veins are then avoided.
Fig. 209. — The Arteries of the Face and Scalp.
•The Facial Artery (fig. 209) arises a little above the lingual, and ascends
obliquely forwards and upwards, beneath the body of the lower jaw, to the sub-
maxillary gland, in which it is imbedded ; this maybe called the cervical part of the
artery. It then curves upwards over the body of the jaw at the anterior inferior
angle of the Masseter muscle, ascends forwards and upwards across the cheek to
the angle of the mouth, passes up along the side of the nose, and terminates at
the inner canthus of the eye, under the name of the angular artery. This vessel,
FACIAL. 375
both in the neck, and on the face, is remarkably tortuous ; in the former situation,
to accommodate itself to the movements 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 integument,
Platysma, and fascia ; it then passes beneath the Digastric and Stylo-hyoid muscles,
and the submaxillary gland. On the face, where it passes over the body of the lower
jaw, it is comparatively superficial, being covered by the Platysma. In this situa-
tion, its pulsation may be distinctly felt, and compression of the vessel effectually
made against the bone. In its course over the face, it is covered by the integu-
ment, the fat of the cheek, and, near the angle of the mouth, by the Platysma and
Zygomatic muscles. It rests on the Buccinator, the Levator anguli oris, and the
Levator labii superioris alceque nasi. It is accompanied by the facial vein
throughout its entire course ; the vein is not tortuous like the artery, and, on the
face, is separated from that vessel by a considerable interval. The branches of
the facial nerve cross this vessel, and the infra-orbital nerve lies beneath it.
The branches of this vessel may be divided into two sets, the cervical, those
given off' below the jaw ; and the facial those on the face.
Cervical Branches. Facial Branches.
Inferior or Ascending Palatine. Muscular.
Tonsillar. Inferior Labial.
Submaxillary. Inferior Coronary.
Submental. Superior Coronary.
Lateralis Nasi.
Angular.
The inferior or ascending palatine (fig. 212) passes up between the Stylo-glossus
and Stylo-pharyngeus to the outer side of the pharynx. After supplying these
muscles, the tonsil, and Eustachian tube, it divides, near the Levator palati, into
two branches ; one follows the course of the Tensor palati, supplies the soft palate
and the palatine glands ; the other passes to the tonsil, which it supplies, anasto-
mosing with the tonsillar artery. These vessels inosculate with the posterior
palatine branch of the internal maxillary artery.
The tonsillar branch (fig. 212) passes up along the side of the pharynx, and,
perforating the Superior constrictor, ramifies in the substance of the tonsil and
root of the tongue.
The submaxillary consist of three or four large branches, which supply the
submaxillary gland, some being prolonged to the neighboring muscles, lymphatic
glands, and integument.
The submental, the largest of the cervical branches, is given off from the facial
artery, just as that vessel quits the submaxillary gland ; it runs forwards upon the
M}do-hyoid muscle, just below the body of the jaw, and beneath the Digastric,
and, after supplying the muscles attached to the jaw, and anastomosing with the
sublingual artery, arrives at the symphysis of the chin, where it divides into a
superficial and a deep branch ; the former turns round the chin, and, passing
between the integument and Depressor labii inferioris, supplies both, and anasto-
moses 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, Masseter, and
Buccinator.
The inferior labial passes beneath the Depressor anguli oris, to supply the
muscles and integument of the lower lip, anastomosing with the inferior coronary
and submental branches of the facial, and with the mental branch of the inferior
dental artery.
The inferior coronary is derived from the facial artery near the angle of the
376 ARTERIES.
mouth ; it passes upwards and inwards beneath the Depressor anguli oris, and,
penetrating the Orbicularis muscle, runs in a tortuous course along the edge of
the lower lip between this muscle and the mucous membrane, inosculating 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,
and mental branch of the inferior dental artery.
The superior coronary is larger, and more tortuous in its course than the pre-
ceding. It follows the same course along the edge of the upper lip, lying between
the mucous membrane and the Orbicularis, 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 artery of
the septum, ramifies on the septum of the nares as far as the point of the nose ;
another 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 artery of the septum, and
the infra-orbital.
The angular artery is the termination of the trunk of the facial ; it ascends to
the inner angle of the orbit, accompanied by a large vein, the angular ; it dis-
tributes some branches on the cheek which anastomose with the infra-orbital, and,
after supplying the lachrymal sac, and Orbicularis muscle, terminates by anas-
tomosing with the nasal branch of the ophthalmic artery.
The anastomoses of the facial artery are very numerous, not only with the
vessel of the opposite side, but with other vessels from different sources ; viz., with
the sublingual branch of the lingual, with the mental branch of the inferior dental
as it emerges from the dental foramen, with the ascending pharyngeal and pos-
terior palatine, and with the ophthalmic, a branch of the internal carotid ; it also
inosculates with the transverse facial, and with the infra-orbital.
Peculiarities. The facial artery not unfrequently arises by a common trunk with the lingual.
This vessel also is 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 cases of hemorrhage from the lips,
the result either of an accidental wound, or from an operation; but its application is useless, 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 a tenaculum. In
order to prevent hemorrhage in cases of excision, or in the removal of diseased growths from the
part, the lip should be compressed on each side between the finger and thumb, 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, almost as deep as its mucous surface; by these means, not only are the cut surfaces more
neatly 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 cutane-
ous portion of the wound, hemorrhage 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, aa
the vessel passes up along the inner margin of the orbit, it ascends on its nasal side. In operat-
ing for fistula lacrymalis, the sac should always be opened on its outer side, in order that this
vessel may be avoided.
The Occipital Artery 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 and Stylo-hyoid muscles, and
part of the parotid gland, the hypoglossal nerve winding around it from behind
forwards ; higher up, it passes across the internal carotid artery, the internal jugular
vein, and the pneumogastric and spinal accessory nerves; it then ascends to the
interval between the transverse process of the atlas and the mastoid process of the
temporal bone, passes horizontally backwards, grooving the surface of the latter bone,
OCCIPITAL— POSTERIOR AURICULAR— PHARYNGEAL. 377
being covered by the Sternomastoid, Splenius, Digastric, and Trackelo-mastoid
muscles, resting upon the Complexus, Superior oblique, and Rectus posticus major
muscles ; it then ascends vertically upwards, piercing the cranial attachment of the
Trapezius, and passes in a tortuous course over the occiput, as high as the vertex,
where it divides into numerous branches.
The branches given off from this vessel are the
Muscular. Inferior meningeal.
Auricular. Arteria princeps cervicis.
The muscular branches supply the Digastric, Stylo-hyoid, Sterno-mastoid,
Splenius, and Trachelo-mastoid muscles. The branch distributed to the Sterno-
mastoid is of large size.
The auricular branch supplies the back part of the concha.
The meningeal branch ascends with the internal jugular vein, and enters the
skull through the foramen lacerum posterius, to supply the dura mater in the
posterior fossa.
The arteria princeps cervicis (fig. 212) is a large branch which descends along
the back part of the neck, and divides into a superficial and deep branch. The
former runs beneath the Splenius, giving off branches which perforate that muscle
to supply the Trapezius, anastomosing with the superficial cervical artery ; the
latter passes beneath the Complexus, between it and the Semi-spinalis colli, and
anastomoses with the vertebral, and deep cervical branch of the superior intercostal.
The anastomosis between these vessels serves mainly to establish the collateral
circulation after ligature of the carotid or subclavian artery.
The cranial branches 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 posterior auricular, and
temporal arteries. They supply the back part of the Occipito-frontalis muscle, the
integument, pericranium, and one or two branches occasionally pass through the
parietal or mastoid foramina, to supply the dura mater.
The Posterior Auricular Artery (fig. 209) 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, to
the groove between the cartilage of the ear and the mastoid process, immediately
above which it divides into two branches, an anterior, which passes forwards to
anastomose with the posterior division of the temporal ; and a posterior, which
communicates with the occipital. Just before arriving at the mastoid process,
this artery is crossed by the portio dura, and has beneath it the spinal accessory
nerve.
Besides several small branches to the Digastric, Stylo-hyoid, and Sterno-mas-
toid muscles, and to the parotid gland, this vessel gives off two branches, the
Stylo-mastoid. Auricular.
The stylo-mastoid branch 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 maxil-
lary, a vascular circle, which surrounds the auditory meatus, and from which
delicate vessels ramify on the membrana tympani.
The auricular branch is distributed to the back part of the cartilage of the ear,
upon which it minutely ramifies, some branches curving round its margin, others
perforating the fibro-cartilage, to supply its anterior surface.
The Ascending- Pharyngeal Artery (fig. 212), 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 Stylo-pharyngeus muscle. It arises
from the back part of the external carotid, near the commencement of that vessel,
and passes up to the under surface of the base of the skull, ascending the neck
between the internal carotid and the side of the pharynx, and lying on the
378 ARTERIES.
Rectus capitis an ticus major. Its branches maybe subdivided into three sets:
1. Those directed outwards to supply muscles and nerves. 2. Those directed
inwards to the pharynx. 3. Meningeal branches.
The external branches are numerous small vessels, which supply the Recti antici
muscles, the sympathetic, hypoglossal and pneumogastric nerves, and the lymphatic
glands of the neck, anastomosing with the ascending cervical artery.
The pharyngeal branches are three or four in number. Two of these descend
to supply the middle and inferior Constrictors and the Stylo-pharyngeus, ramifying
in their substance and in the mucous membrane lining them. The largest of the
pharyngeal branches passes inwards, running upon the Superior constrictor, and
sends ramifications to the soft palate, Eustachian tube, and tonsil, which take the
place of the ascending palatine branch of the facial artery, when that vessel is of
small size.
The meningeal branches consist of several small vessels, which pass through
foramina in the base of the skull, to supply the dura mater. One, the posterior
meningeal, enters the cranium through the foramen lacerum posterius with the
internal jugular vein. A second passes through the foramen lacerum basis cranii ;
and occasionally a third through the anterior condyloid foramen. They are all
distributed to the dura mater.
The Temporal Artery (fig. 209), 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 condyle of the lower jaw and the external meatus ; cross-
ing over the root of the zygoma, immediately beneath the integument, it divides
about two inches above the zygomatic arch into two branches, an anterior and a
posterior.
The anterior temporal inclines forwards over the forehead, supplying the
muscles, integument, and pericranium in this region, and anastomoses with the
supra-orbital and frontal arteries, its branches being directed from before back-
wards.
The posterior temporal, larger than the anterior, curves upwards and back-
wards along the side of the head, lying above the temporal fascia, and inosculates
with its fellow of the opposite side, and with the posterior auricular and occipital
arteries.
The temporal artery, as it crosses the zygoma, is covered by the Attrahens
aurem muscle, and by a dense fascia given off from the parotid gland ; it is also
usually crossed by one or two veins, and accompanied by branches of the facial
and temporo-auricular nerves. Besides some twigs to the parotid gland, the
articulation of the jaw, and the Masseter muscle, its branches are the
Transverse facial. Middle temporal.
Anterior auricular.
The transverse facial is given off from the temporal before that vessel quits the
parotid gland ; running forwards through its substance, it passes transversely
across the face, between Stenon'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 integument, anastomosing with the facial
and infra-orbital arteries. This vessel rests on the Masseter, and is accompanied
by one or two branches of the facial nerve.
The middle tempioral artery arises immediately above the zygomatic arch, and,
perforating the temporal fascia, supplies 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 ; it supplies the
Orbicularis, and anastomoses with the lachrymal and palpebral branches of the
ophthalmic artery.
INTERNAL MAXILLARY. 379
The anterior auricular branches 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. It occasionally happens that the surgeon is called upon to perform the
operation of arteriotomy upon this vessel in cases of inflammation of the eye or brain. Under
these circumstances, the anterior branch is the one usually selected. If the student will con-
sider the relations of the trunk of this vessel as it crosses the zygomatic arch, with the surround-
ing structures, he will observe that it is covered by a thick and dense fascia, crossed by one or
' two veins, and accompanied by branches of the facial and temporo-auricular nerves. Bleeding
should not be performed in this situation, as much difficulty may arise from the dense fascia
covering this vessel preventing a free flow of blood, and considerable pressure is requisite after-
wards to repress it. Again, a varicose aneurism may be formed by the accidental opening of one
of the veins covering it; or severe neuralgic pain may arise from the operation implicating one of
the nervous filaments which accompany the artery.
The anterior branch is, on the contrary, subcutaneous, is a large vessel, and as readily com-
pressed as any other portion of the artery ; it should consequently always be selected for the
operation.
The Internal Maxillary, the larger of the two terminal branches of the
external carotid, passes inwards, at right angles from that vessel, to the inner side
of the neck of the condyle of the lower jaw, to supply the deep structures of the
face. At its origin, it is imbedded in the substance of the parotid gland, being
on a level with the lower extremity of the lobe of the ear.
In the first part of its course (maxillary portion), the artery passes horizon-
tally forwards and inwards, between the ramus of the jaw and the internal late-
ral ligament. The artery here lies parallel with the auriculo-temporal nerve ; it
crosses the inferior dental nerve, and lies beneath the narrow portion of the Ex-
ternal pterygoid muscle.
In the second part of its course (pterygoid portion), it ascends obliquely for-
wards and upwards 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.
In the third part of its course (spheno-maxillary portion), it approaches the
superior maxillary bone, and enters the spheno-maxillary fossa, in the interval
between the processes of origin of the External pterygoid, where it lies in rela-
tion with Meckel's ganglion, and gives off its terminal branches.
Peculiarities. Occasionally, this artery passes between the two Pterygoid muscles. The ves-
sel in this case passes forwards to the interval between the processes of origin of the External
pterygoid, in order to reach the maxillary bone. Sometimes the vessel escapes from beneath the
External pterygoid by perforating the middle of this muscle.
The branches of this vessel may be divided into three groups, corresponding
with its three divisions.
1. Branches from the Maxillary Portion.
Tympanic. Small meningeal.
Middle meningeal. Inferior dental.
The tympanic branch passes upwards behind the articulation of the lower jmv,
enters the tympanum through the fissura Glaseri, supplies the Laxator tympani,
and ramifies upon the membrana tympani, anastomosing with the stylo-mastoid
and Vidian arteries.
The middle meningeal is the largest of the branches which supply the dura
mater. It arises from, the internal maxillary between the internal lateral ligament
and the neck of the jaw, and ascends vertically upwards to the foramen spinosum
in the spinous process of the sphenoid bone. On entering the cranium, it divides
into two branches, an anterior and a 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 branches which
380
ARTERIES.
spread out between the dura mater and internal surface of the cranium, some
passing upwards over the parietal bone as far as the vertex, and others backwards
to the occipital 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 mater and cranium. The branches of this
vessel are distributed to the dura mater, but chiefly to the bones; they anastomose
Fig. 210. — The Internal Maxillary Artery, and its Branches.
tPttryqe 'Palatini
f I & . 211. Elan cf the franc hes [^tZ^naFaMin.
\SplunPalat\itt
with the arteries of the opposite side, and with the anterior and posterior menin-
geal.
The middle meningeal, on entering the cranium, gives off the following colla-
teral branches: 1. Numerous small vessels to the ganglion of the fifth nerve,
and to the dura mater in this situation. 2. A branch to the facial nerve, which
enters the hiatus Fallopii, supplies the facial nerve, and anastomoses with the stylo-
mastoid branch of the posterior auricular artery. 3. 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 oph-
thalmic artery. 4. Temporal branches, which pass through foramina in the great
wing of the sphenoid, and anastomose in the temporal fossa with the deep temporal
arteries.
The small meningeal is sometimes derived from the preceding. It enters the
skull through the foramen ovale, and supplies the Casserian ganglion and dura
INTERNAL MAXILLARY. 381
mater. Before entering the cranium, it gives off a branch to the nasal fossa and
soft palate.
The inferior dental descends with the 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 bicuspid tooth divides into
two branches, incisor and mental ; the former is continued forwards beneath the
incisor teeth as far as the symphysis, where it anastomoses with the artery of the
opposite side ; the mental branch 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. As the dental artery enters the
foramen, it gives off a mylo-hyoid branch, 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 diploe, and a series of branches which corre-
spond in number to the roots of the teeth ; these enter the minute apertures at
the extremities of the fangs, and ascend to supply the pulp of the teeth.
2. Branches of the Second or Pterygoid Portion.
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 and 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 other temporal arteries ; the anterior branch communicating with the lach-
rymal through small branches which perforate the malar bone.
The pterygoid branches, irregular in their number and origin, supply the Ptery-
goid muscles.
The masseteric is a small branch which passes outwards above the sigmoid
notch of the lower jaw, to the deep surface of the Masseter. It supplies that
muscle, and anastomoses with the masseteric branches of the facial and transverse
facial arteries.
The buccal is a small branch which runs obliquely forwards 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.
3. Branches of the Third or Spheno-maxillary Portion.
Alveolar. Vidian.
Infra-orbital. Ptery go-palatine.
Posterior or Descending palatine. Nasal or Spheno-palatine.
The alveolar is given off from the internal maxillary by a common branch with
the infra-orbital, 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 ; one, the superior dental, larger than the rest,
supplies the molar and biscuspid teeth, its branches entering the foramina in
the alveolar process ; some branches pierce the bone to supply the lining of the
antrum, and others are continued forwards on the alveolar process to supply the
gums.
The infra-orbital appears, from its direction, to be the continuation 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. Whilst contained in the canal, it gives off' branches
which ascend into the orbit, and supply the Inferior rectus, and Inferior oblique
382 SURGICAL ANATOMY.
muscles, and the lachrymal gland. Other branches descend through canals hi tha
bone, to supply the mucous membrane of the antrum, and the front teeth of the
upper jaw. On the face, it supplies the lachrymal sac, and inner angle of the
orbit, anastomosing with the facial artery and nasal branch of the ophthalmic;
and other branches descend beneath the elevator of the upper lip, and anastomose
with the transverse facial and buccal branches.
The four remaining branches arise from that portion of the internal maxillary
which is contained in the spheno-maxillary fossa.
The descending palatine passes down along the posterior palatine canal with the
posterior palatine branches of Meckel's ganglion, and, emerging from the posterior
palatine foramen, runs forwards in a groove on the inner side of the alveolar
border of the hard palate, to be distributed to the gums, the mucous membrane
of the hard palate, and 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, anastomosing with the ascending palatine artery ; and ante-
riorly it terminates in a small vessel, which ascends in the anterior palatine canal,
and anastomoses with the artery of the septum, a branch of the spheno-palatine.
The Vidian branch passes backwards 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.
The pterygopalatine is also a very small branch, which passes backwards
through the pterygopalatine canal with the pharyngeal nerve, and is distributed
to the upper part of the pharynx and Eustachian tube.
The nasal or spheno-palatine 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 artery of the septum, passes obliquely downwards
and forwards along the septum nasi, supplies the mucous membrane, and anasto-
moses in front with the ascending branch of the descending palatine. The
external branches, two or three in number, supply the mucous membrane cover-
ing the lateral wall of the nares, the antrum, and the ethmoid and sphenoid cells.
Surgical Anatomy of the Triangles of the Neck.
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 being con-
stantly performed.
For this purpose, the Sterno-mastoid, or any other muscles that have been
divided in the dissection of these vessels, should be replaced in their normal posi-
tion ; the head should be supported by placing a block at the back of the neck,
and the face turned to the side opposite to that which is being examined.
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 trian-
gular space in front of this muscle is called the anterior triangle; and that behind
it, the posterior triangle.
Anterior Triangular Space.
The anterior triangle is limited, in front, by a line extending from the chin to
the sternum; behind, by the anterior margin of the Sterno-mastoid; its base,
directed upwards, is formed by the lower border of the body of the jaw, and a line
OF THE TRIANGLES OF THE NECK. 383
extending from the angle of the jaw to the mastoid process ; its apex is formed
below by the sternum. This space is covered by the integument, superficial
fascia, Platysma, deep fascia, crossed by branches of the facial and superficial cer-
vical nerves, and subdivided into three smaller triangles by the Digastric muscle,
above, and the anterior belly of the Omo-hyoid, below. These are named, from
below upwards, the inferior carotid triangle, the superior carotid triangle, and the
submaxillary triangle.
The Inferior Carotid Triangle, is limited, 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 it is covered by the integument, superficial fascia,
Platysma, and deep fascia ; ramifying between which is seen the descending
branch of the superficial cervical nerve. 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.
This vessel is inclosed within its sheath, together with the internal jugular vein,
and pneumogastric nerve; the vein lying on the outer side of the artery on the
right side of the neck, but overlapping it, or passing directly across it 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 communi-
cation between the descendens and communicans noni ; behind the sheath are seen
the inferior thyroid artery, the recurrent laryngeal and sympathetic nerves ; 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. In the upper part of
this space, the common carotid artery may be tied below the Omo-hyoid muscle.
The Superior Carotid Triangle 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. Its floor is formed by parts of the Thyro-hyoid, Hyo-
glossus, and the inferior and middle Constrictor muscles of the pharynx ; and it is
covered by the integument, superficial fascia, Platysma, and deep fascia; rami-
fying between which are branches of the facial and superficial cervical nerves.
This space contains the upper part of the common carotid artery, which bifurcates
opposite the upper border of the thyroid cartilage into the external and internal
carotid. These vessels are concealed from view by the anterior margin of the
Sterno-mastoid muscle, which overlaps them. The external and internal carotids
lie side by side, the external being the most anterior of the two. The following
branches of the external carotid are also met with in this space : the superior
thyroid, which runs forwards and downwards ; the lingual, which passes directly
forwards ; the facial, forwards and upwards ; the occipital is directed backwards ;
and the ascending pharyngeal runs directly upwards on the inner side of the in-
ternal carotid. The veins met with are: — the internal jugular, which lies on the
outer side of the common and internal carotid vessels ; 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.
In front of the sheath of the common carotid is the descendens noni, the hypo-
glossal, from which it is derived, crossing both carotids above, curving round the
occipital artery at its origin. Within the sheath, between the artery and vein,
and behind both, is the pneumogastric nerve ; behind the sheath, the sympathetic.
On the outer side of the vessels, the spinal accessory nerve runs for a short distance
before it pierces the Sterno-mastoid muscle ; and on the inner side of the internal
carotid, just below the hyoid bone, may be seen the superior laryngeal nerve ; and
still more inferiorly, the external laryngeal nerve. The upper part of the larynx
and the pharynx are also found in the front part of this space.
The Submaxillary Triangle corresponds to that 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, the parotid gland, and mastoid process ; behind by the posterior
belly of the Digastric and Stylo-hyoid muscles : in front, by the middle line of
384 SURGICAL ANATOMY.
the neck. The floor of this space is formed by the anterior belly of the Digastric,
the Mylo-hyoid, and Hyo-glossus muscles, and 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 nerve. This space
contains, in front, the submaxillary gland, imbedded in the surface of which is the
facial artery and vein, and its glandular branches ; beneath this gland, on the sur-
face of the Mylo-hyoid muscle, are the submental artery, and the mylo-hyoid artery
and nerve. The back part of this space is separated from the front 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 super-
ficial 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, the internal jugular vein, and the pneumogastric
nerve, separated from the external carotid by the Stylo-glossus and Stylo-pharyn-
geus muscles, and the glosso-pharyngeal nerve.
Posteeior Triangular Space.
The posterior triangular space is bounded, in front, by the Sterno-mastoid
muscle ; behind, by the anterior margin of the Trapezius ; its base corresponds to
the upper border of the clavicle, its apex to the occiput. This space is crossed,
about an inch above the clavicle, by the posterior belly of the Omo-hyoid, which
divides it unequally into two triangles, an upper or occipital, and a lower or
subclavian.
The Occipital, the larger of the two posterior triangles, is bounded, in front,
by the Sterno-mastoid ; behind, by the Trapezius ; below, by the Omo-hyoid. Its
floor is formed from above downwards 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, and crossed, above, by the
ascending branches of the cervical plexus : the spinal accessory nerve is directed
obliquely across the space from the Sterno-mastoid, which it pierces, to the under
surface of the Trapezius; below, it is crossed by the descending branches of the
same plexus, and the transversalis colli artery and vein. 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, 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
forwards, being formed by the Sterno-mastoid. The size of this space 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. The height also of this space varies
much, according to the position of the arm, being much diminished on raising the
limb, on account of the ascent of the clavicle, and increased on drawing the arm
downwards, when this bone is consequently depressed. This space is covered
by the integument, superficial and deep fascioa ; 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 outwards and downwards 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
intermediate between this and its usual level. Occasionally, it passes in front of
the Scalenus anticus, or pierces the fibres of this muscle. The subclavian vein
lies beneath 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 across the clavicular margin
of the space, are the suprascapular vessels ; and traversing its upper angle in the
same direction, the transverse cervical vessels. The external jugular vein descends
INTERNAL CAROTID.
385
vertically downwards behind the posterior border of the Sterno-mastoid, to terminate
in the Subclavian; 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 also
crosses this space about its centre.
Internal Carotid Artery.
The Internal Carotid Artery commences at the bifurcation of the common
carotid, opposite the upper border of the thyroid cartilage, and ascends perpen-
dicularly upwards, in front of the transverse processes of the three upper cervical
vertebrae, to the carotid foramen in the petrous portion of the temporal bone.
Fig. 212. — The Internal Carotid and Vertebral Arteries. Right Side.
386 ARTERIES.
After ascending in it for a short distance, it passes forwards and inwards through
the carotid canal, and, ascending a little by the side of the sella Turcica, curves
upwards by the anterior clinoid process, where it pierces the dura mater, and
divides into its terminal branches.
This vessel supplies the anterior part of the brain, the eye, and its appendages.
Its size, in the adult, is equal to that of the external carotid. 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. In its cervical portion it occasionally pre-
sents one or two flexures near the base of the skull, whilst through the rest of its
extent it describes a double curvature, which resembles the italic letter / placed
horizontally S>. These curvatures most probably diminish the velocity of the
current of blood, by increasing the extent of surface over which it moves, and
adding to the amount of impediment produced from friction. In considering the
course and relations of this vessel, it may be conveniently divided into four por-
tions, a cervical, petrous, cavernous, and cerebral.
Cervical Portion. This portion of the internal carotid at its commencement is
very superficial, being contained in the superior carotid triangle, on the same level
as, but behind, the external carotid, overlapped by the Sterno-mastoid, and covered
by the Platysma, deep fascia, and integument ; it then passes beneath the parotid
gland, being crossed by the hypoglossal nerve, the Digastric and Stylo-hyoid
muscles, and the external carotid and occipital arteries. Higher up, it is separated
from the external carotid by the Stylo-glossus and Stylo-pharyngeus muscles, the
glossopharyngeal nerve, and pharyngeal branch of the vagus. It is in relation,
behind, with the Rectus anticus major, the superior cervical ganglion of the
sympathetic, and superior laryngeal nerve ; externally, with the internal jugular
vein, and pneumogastric nerve ; internally, with the pharynx, tonsil, and ascend-
ing pharyngeal artery.
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
forwards and inwards, and again ascends as it leaves the canal to enter the cavity
of the skull. In this canal, the artery lies at first anterior to the tympanum,
from which it is separated by a thin bony lamella, which is cribriform in the
young subject, and often absorbed in old age. It is separated from the bony wall
of the carotid canal by a prolongation of dura mater, and is surrounded by fila-
ments of the carotid plexus.
Cavernous Portion. The internal carotid artery, in this part of its course, at first
ascends to the posterior clinoid process, then passes forwards by the side of the
body of the sphenoid bone, being situated on the inner wall of the cavernous
sinus, in relation, externally, with the sixth nerve, and covered by the lining
membrane of the sinus. The third, fourth, and ophthalmic nerves are placed on
the outer wall of the sinus, being separated from its cavity by the lining membrane.
Cerebral Portion. On the inner side of the anterior clinoid process the internal
carotid curves upwards, perforates the dura mater bounding the sinus, and is
received into a sheath of the arachnoid. This portion of the artery is on the
outer side of the optic nerve ; it lies at the inner extremity of the fissure of
Sylvius, having the third 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 was placed nearer the
middle line of the neck than the external carotid, as far upwards 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 ascended the neck, and gave off the usual branches of the external
carotid, the craninl portion of the vessel being replaced by two branches of the internal maxil-
lary, which entered the skull through the foramen rotundum and foramen ovale, and joined to form
a single vessel.
Surgical Anatomy. The cervical part of the internal carotid is sometimes wounded by a stab
or gunshot wound in the neck, or even occasionally by a stab from within the mouth, as when
OPHTHALMIC.
387
a person receives a thrust from the end of a parasol, or falls down with a tobacco-pipe in his
mouth. In such cases a ligature should be applied to the common carotid. Its relation with
the tonsil should be especially remembered, as instances have occurred in which the artery has
been wounded, during the operation of scarifying the tonsil, and fatal hemorrhage has super-
vened.
The branches given off from the internal carotid are : —
From the Petrous Portion
From the Cavernous Portion
From the Cerebral Portion
Tympanic.
( Arteria receptaculi.
< Anterior meningeal.
( Ophthalmic,
f Anterior cerebral.
J Middle cerebral.
I Posterior communicating.
(_ Anterior choroid.
The cervical portion of the internal carotid gives off no branches.
The tympanic is a small branch 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 stylo-mastoid arteries.
The arterise receptaculi are numerous small vessels, derived from the internal
carotid in the cavernous sinus ; they supply the pituitary body, the Casserian gan-
glion, and the walls of the cavernous and inferior petrosal sinuses. One of these
branches, distributed to the dura mater, is called the anterior meningeal; it anas-
tomoses with the middle meningeal.
The Ophthalmic Artery arises from the internal carotid, just as that vessel
is emerging from the cavernous sinus, on the inner side of the anterior clinoid
Fig. 213. — The Ophthalmic Artery and its Brandies, the Roof of the Orbit having been
removed.
Katal PaJfthral
Itvntal
AnUrior X3i<™>Xo.1-
Ftuttritr JSSibo.
Oplukalmio
Tntemat Carotid
process, and enters the orbit through the optic foramen, below, and on the outer
side of, the optic nerve. It then crosses above, and to the inner side of, this
nerve, to the inner wall of the orbit, and passing horizontally forwards, beneath
388 ARTERIES.
the lower border of the Superior oblique muscle, passes to the inner angle of the
eye, where it divides into two terminal branches, the frontal and nasal.
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. Ocular Group.
Lachrymal. . Muscular.
Supra-orbital. Anterior ciliary.
Posterior ethmoidal. Short ciliary.
Anterior ethmoidal. Long ciliary.
Palpebral. Arteria centralis retinae.
Frontal.
Nasal.
The lachrymal is the first, and one of the largest branches, derived from the
ophthalmic, arising close to the optic foramen, and not unfr^quently from that
vessel before entering the orbit. It accompanies the lachrymal nerve along the
upper border of the External rectus muscle, and is distributed to the lachrymal
gland. Its terminal branches, escaping from the gland, are distributed to the
upper eyelid and conjunctiva, anastomosing with the palpebral arteries. The
lachrymal artery gives off one or two malar 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, and anasto-
moses with the transverse facial. A branch is also sent backwards, through the
sphenoidal fissure, to the dura mater, which anastomoses with a branch of the
middle meningeal artery.
Peculiarities. The lachrymal artery is sometimes derived from one of the anterior branches
of the middle meningeal artery.
The supra-orbital artery, the largest branch of the ophthalmic, arises from that
vessel above the optic nerve. Ascending so as to rise above all the muscles of
the orbit, it passes forwards, with the frontal nerve, between the periosteum and
Levator palpebrae ; and, passing through the supra-orbital foramen, divides into a
superficial and deep branch, which supply the muscles and integument of the
forehead and pericranium, anastomosing with the temporal, angular branch of the
facial, and the artery of the opposite side. This artery in the orbit supplies the
Superior rectus and the Levator palpebral sends a branch inwards, across the
pulley of the Superior oblique muscle, to supply the parts at the inner canthus,
and at the supra-orbital foramen frequently transmits a branch to the diploe.
The ethmoidal branches are two in number, posterior and 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
meningeal branch, which supplies the adjacent dura mater, and nasal branches,
which descend into the nose through apertures in the cribriform plate, anasto-
mosing 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, divides
into a meningeal branch, which supplies the adjacent dura mater, and a nasal
branch which descends into the nose, through an aperture in the cribriform
plate.
The palpebral arteries, two in number, superior and inferior, arise from the
ophthalmic, opposite the pulley of the Superior oblique muscle ; they encircle the
eyelids near their free margin, forming a superior and an inferior arch, which lie
between the Orbicularis muscle and tarsal cartilages; the superior palpebral
inosculating at the outer angle of the orbit with the orbital branch of the
temporal artery; the inferior palpebral anastomosing with the orbital branch of the
infra-orbital artery, at the inner side of the lid. From this anastomosis, a branch
OPIITHALMIC.
389
passes to the nasal duet, ramifying, in its mucous membrane, as far as the inferior
meatus.
Fig. 214.— The Arteries of the Base of the Brain. The Right Half of the Cerebellum and
Pons have been removed.
The fron tal artery, one of the terminal branches of the ophthalmic, passes from
the orbit at its inner angle, and, ascending on the forehead, supplies the muscles,
integument, and pericranium, anastomosing with the supra-orbital artery.
The nasal artery, the other terminal branch of the ophthalmic, emerges from
the orbit above the tendo oculi, and, after giving a branch to the lachrymal sac,
390 ARTERIES.
divides into two, one of which anastomoses with the angular artery ; the other
branch, the dorsalis nasi, runs along the dorsum of the nose, supplies its entire
surface, and anastomoses with the artery of the opposite side.
The ciliary arteries are divisible into three groups, the short, long, and
anterior.
The short ciliary . arteries, from twelve to fifteen in number, arise from the
ophthalmic, or some of its branches ; they surround the optic nerve as they pass
forwards to the posterior part of the eyeball, pierce the sclerotic coat around the
entrance of this nerve, and supply the choroid coat and ciliary processes.
The long ciliary arteries, two in number, also pierce the posterior part of the
sclerotic, and run forwards, along each side of the eyeball, between the sclerotic
and choroid, to the ciliary ligament, where they divide into two branches ; these
form an arterial circle around the circumference of the iris, from which numerous
radiating branches pass forwards, in its substance, to its free margin, where they
form a second arterial circle around its pupillary margin.
The anterior ciliary arteries are derived from the muscular branches; they
pierce the sclerotic a short distance from the cornea, and terminate in the great
arterial circle of the iris.
The arteria centralis retinse is one of the smallest branches of the ophthalmic
artery. It arises near the optic foramen, pierces the optic nerve obliquely, and
runs forwards, in the centre of its substance, to the retina, in which its branches
are distributed as far forwards as the ciliary processes. In the human foetus, a
small vessel passes forwards, through the vitreous humor, to the posterior surface
of the capsule of the lens.
The muscular branches, two in number, superior and inferior, supply the
muscles of the eyeball. The superior, the smaller, often wanting, supplies the
Levator palpebrse, Superior rectus, and Superior oblique. The inferior, more
constant in its existence, passes forwards, between the optic nerve and Inferior
rectus, and is distributed to the External and Inferior recti, and Inferior oblique.
This vessel gives off most of the anterior ciliary arteries.
The Cerebral Branches of the internal carotid are, the anterior cerebral, the
middle cerebral, the posterior communicating, and the anterior choroid.
The anterior cerebral arises from the internal carotid, at the inner extremity of
the fissure of Sylvius. It passes forwards in the great longitudinal fissure between
the two anterior lobes of the brain, being connected, soon after its origin, with the
vessel of the opposite side by a short anastomosing trunk, about two lines in length,
the anterior communicating. The two anterior cerebral arteries, lying side by side,
curve round the anterior border of the corpus callosum, and run along its upper
surface to its posterior part, where they terminate by anastomosing with the
posterior cerebral arteries. They supply the olfactory and optic nerves, the under
surface of the anterior lobes, the third ventricle, the anterior perforated space,
the corpus callosum, and the inner surface of the hemispheres.
The anterior communicating artery is a short branch, about two lines in length,
but of moderate size, connecting together the two anterior cerebral arteries across
the longitudinal fissure. Sometimes this vessel is wanting, the two arteries joining
together to form a single trunk, which afterwards subdivides ; or the' vessel may
be wholly or partially subdivided into two ; frequently, it is longer and smaller
than usual.
The middle cerebral artery, the largest branch of the internal carotid, passes
obliquely outwards along the fissure of Sylvius, within which it divides into three
branches : an anterior, which supplies the pia mater, investing the surface of the
anterior lobe ; a posterior, which supplies the middle lobe ; and a median branch,
which supplies the small lobe at the outer extremity of the Sylvian fissure. Near
its origin, this vessel gives off numerous small branches, which enter the substantia
perforata, to be distributed to the corpus striatum.
The 2losier"l'or communicating artery arises from the back part of the internal
carotid, runs directly backwards, and anastomoses with the posterior cerebral, a
SUBCLAVIAN. 391
branch of the basilar. This artery varies considerably in size, being sometimes
small, and occasionally so large that the posterior cerebral 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.
The anterior choroid is a small but constant branch which arises from the back
part of the internal carotid, near the posterior communicating artery. Passing
backwards and outwards, it enters the descending horn of the lateral ventricle,
beneath the edge of the middle lobe of the brain. It is distributed to the hippo-
campus major, corpus flmbriatum, and choroid plexus.
ARTERIES OF THE UPPER EXTREMITY.
The artery which supplies the upper extremity, continues as a single trunk from
its commencement, as far as the elbow ; but different portions of it have received
different names, according to the region through which it passes. Thus, that
part of the vessel which extends from its origin, as far as the outer border of
the first rib, ds termed the subclavian ; beyond this point to the lower border of
the axilla, it is termed the axillary ; and from the lower margin of the axillary
space to the bend of the elbow, it is termed the brachial ; 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.
Subclavian Aeteries.
The Subclavian Artery on the right side arises from the arteria innominata,
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 in their relation
with neighboring parts.
In order to facilitate the description of these vessels, more especially in a sur-
gical point of view, each subclavian artery has been divided into three parts.
The first portion, on the right side, ascends obliquely outwards, from the origin of
the vessel to the inner border of the Scalenus anticus. On the left side, it ascends
perpendicularly to the inner border of that muscle. The second part passes out-
wards, behind the Scalenus anticus; and the third part passes from the outer
margin of that muscle, beneath the clavicle, to the lower border of the first rib,
where it becomes the axillary artery. The first portions of these two vessels differ
so much in their course, and in their relation with neighboring parts, that they
will be described separately. The second and third parts are precisely alike on
both sides.
First Part of the Right Subclavian Artery (figs. 205 and 207).
It arises from the arteria innominata, opposite the right sterno-clavicular arti-
culation, passes upwards and outwards across the root of the neck, and terminates
at the inner margin of the Scalenus anticus muscle. In this part of its course, it
ascends a little above the clavicle, the extent to which it does so varying in different
cases. It is covered, in front, by the integument, • superficial fascia, Platysma, deep
fascia, the clavicular origin of the Sterno-mastoid, the Sterno-hyoid and Sterno-
thyroid muscles, and another layer of the deep fascia. It is crossed by the
internal jugular and vertebral' veins, and by the pneumogastric, the cardiac
branches of the sympathetic, and phrenic nerves. Beneath, the artery is invested
by the pleura, and behind, it is separated by a cellular interval from the Longus
colli, the transverse process of the seventh cervical vertebra, and the sympathetic;
the recurrent laryngeal nerve winding around the lower and back part of this
vessel. The subclavian vein lies below the subclavian artery, immediately behind
the clavicle.
392 ARTERIES.
Plan of Relations of First Portion of Right Subclavian Artery.
In front.
Integument and superficial fascia.
Platysma and deep fascia.
Clavicular origin of Sterno-mastoid.
Sterno-hyoid and Sterno-thyroid.
Internal jugular and vertebral veins.
Pneumogastric, cardiac, and phrenic nerves.
Beneath.
Pleura.
Behind.
Recurrent laryngeal nerve.
Sympathetic.
Longus colli. ,
Transverse process of seventh cervical vertebra.
First Part of the Left Subclavian Artery (fig. 205).
It arises from the end of the transverse portion of the arch of the aorta, oppo-
site the second dorsal vertebra, and ascends to the inner margin of the first rib,
behind the insertion of the Scalenus anticus muscle. This vessel is, therefore,
longer than the right, situated more deeply in the cavity of the chest, and
directed almost vertically upwards, instead of arching outwards like the vessel of
the opposite side.
It is in relation, in front, with the pleura, the left lung, the pneumogastric,
phrenic, and cardiac nerves, which lie parallel with it, the left carotid artery, left
internal jugular and innominate veins, and is covered by the Sterno-thyroid,
Sterno-hyoid, and Sterno-mastoid muscles ; behind, with the oesophagus, thoracic
duct, inferior cervical ganglion of the sympathetic, Longus colli, and vertebral
column. To its inner side, are the oesophagus, trachea, and thoracic duct ; to its
outer side, the pleura.
Plan of Relations of First Portion of Left Subclavian Artery.
In front.
Pleura and left lung.
Pneumogastric, cardiac, and phrenic nerves.
Left carotid artery.
Left internal jugular and innominate veins.
Sterno-thyroid, Sterno-hyoid, and Sterno-mastoid muscles.
Inner side. / \ Outer side.
(Esophagus. / _ tL,eft. \ Pleura.
I rachea.
Thoracic duct.
Behind.
(Esophagus and thoracic duct.
Inferior cervical ganglion of sympathetic.
Longus colli and vertebral column.
The relations of the second and third portions of the subclavian arteries are
precisely similar on both sides.
The Second Portion of the Subclavian Artery lies between the two Scaleni
muscles ; it is very short, and forms the highest part of the arch described by that
vessel.
SUBCLAVIAN.
393
Relations. It is covered, in front, by the integument, Platysma, Sterno- mastoid,
cervical fascia, and by the phrenic nerve, which is separated from the artery by
the Scalenus anticus muscle. Behind, it is in relation with the Middle scalenus.
Above, with the brachial plexus of nerves. Below, with the pleura. The sub-
clavian vein lies below and in front of the artery, separated from it by the Scalenus
anticus. „
Plan of Eelations of Second Portion of Subclavian Artery.
In front.
Platysma.
Stern o-mastoid.
Cervical fascia.
Scalenus anticus.
Phrenic nerve.
Subclavian Vein.
Above.
Brachial plexus.
Beloio.
Pleura.
Behind.
Middle scalenus.
The Third Portion of the Subclavian Artery passes downwards and outwards
from the outer margin of the Scalenus anticus to the lower border of the first
rib, where it becomes the axillary artery. This portion of the vessel is the most
superficial, and is contained in a triangular space, the base of which is formed in
front by the Anterior scalenus, and the two sides by the Omo-hyoid above and
the clavicle below.
Relations. It is covered, in front, by the integument, the superficial fascia, the
Platysma, deep fascia ; and by the clavicle, the Subclavius muscle, and the supra-
scapular artery and vein; the clavicular descending branches of the cervical
plexus and the nerve to the Subclavius pass vertically downwards in front of the
artery. The external jugular vein crosses it at its inner side, and receives the
suprascapular and transverse cervical veins, which occasionally form a plexus in
front of it. The subclavian vein is below the artery, lying close behind the
clavicle. Behind, it lies on the Middle scalenus muscle. Above it, and to its
outer side, are the brachial plexus and Omo-hyoid muscle. Below, it rests on the
outer surface of the first rib.
Plan of Eelations of Third Portion of Subclavian Artery.
In front.
Integument, fasciae, and Platysma.
The external jugular, suprascapular, and transverse cervical veins.
Descending branches of cervical plexus.
Subclavius muscle, suprascapular artery, and clavicle.
Above.
Brachial plexus.
Omo-hyoid.
Below.
First rib.
Behind.
Scalenus medius.
Peculiarities. The subclavian arteries vary in their origin, their course, and in 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; more frequently in the cavity of the thorax, below that joint. Or
394 ARTERIES.
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 towards the right side, behind the oesophagus and right carotid, sometimes between the
oesophagus and trachea, to the upper border of the first rib, where it follows its ordinary course.
In very rare instances, this vessel arises from the thoracic aorta, as low down as the fourth dorsal
vertebra. Occasionally it perforates the Anterior scalenus ; more rarely it passes in front of this
muscle : sometimes the subclavian vein passes with the artery behind the Scalenus. The artery
sometimes ascends as high as an inch and a half above the clavicle, or to any intermediate point
between this and the upper border of this bone, the right subclavian usually ascending higher
than the left.
The left subclavian is occasionally joined at its origin with the left carotid.
Surgical Anatomy. The relations of the subclavian arteries of the two sides having been
examined, the student should direct his attention to consider the best position in which compres-
sion of the vessel may be effected, or in what situation a ligature may be best applied in cases of
aneurism or wounds.
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 outer
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, may press with his thumb in the hollow
behind the clavicle downwards against the rib ; if from any cause the shoulder cannot be suffi-
ciently depressed, pressure may be made from before backwards, so as to compress the artery
against the Middle scalenus and transverse process of the seventh cervical vertebra.
Ligature of the subclavian artery may be required in cases of wounds of the axillary artery, or
in aneurism of that vessel ; and the third part of the artery is consequently that which is most
favorable for such an operation, on account of its being comparatively superficial, and most re-
mote 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 elevated
from the presence of 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 circum-
stances, 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
as high as an inch and a half, and sometimes so low as to be on a level with its upper border.
If displacement of the clavicle occurs, 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 fol-
lows : The patient being placed on a table in the horizontal position, and the shoulder depressed
as much as possible, the integument should be drawn downwards upon the clavicle and an inci-
sion 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 centre
of the preceding; the Platysma and cervical fascia should be divided upon a director, and if the
interval between the Trapezius and Sterno-mastoid muscles be insufficient for the performance
of the operation, a portion of one or both -may be divided. The external jugular vein will now be
seen towards the inner side of the wound ; this and the suprascapular and transverse cervical veins
which terminate in it should be held aside, and if divided both ends should be included in a ligature :
the suprascapular artery should be avoided, and the Omo-hyoid muscle must now be looked for,
and held aside if necessary. In the space beneath this muscle, careful search must be made for
the vessel ; the deep fascia having been divided with the finger-nail or silver scalpel, the outer
margin of the Scalenus muscle must be felt for, and the finger being guided by it to the first rib,
the pulsation of the subclavian artery will be felt as it passes over its surface. The aneurism
needle may then be passed around the vessel from before backwards, by which means the vein
will be avoided, care being taken not to include a branch of the brachial plexus instead of the
artery in the ligature. If the clavicle is so raised by the tumor that the application of the liga-
ture cannot be effected in this situation, the artery may be tied above the first rib, or even behind
the Scalenus muscle : the difficulties of the operation in such a case will be materially increased,
on account of the greater depth of the artery, and alteration of the surrounding parts.
The second division of the subclavian artery, from being that portion which rises highest
in the neck, has been considered favorable for the application of the ligature, where it is diffi-
cult to apply it in the third part of its course. There are, however, many objections to the
operation 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; 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 prox-
imity of so many of its larger branches arising internal to this point, must be a still further
SUBCLAVIAN.
395
objection to the operation. If, however, it has been determined upon to perform the operation
in this situation, it should be remembered that it occasionally happens, that the artery passes in
front of the Scalenus anticus, or through the fibres of that muscle ; or that the vein sometimes
passes with the artery behind the Scalenus anticus.
In those cases of aneurism of the axillary or subclavian artery which encroach upon the outer
portion of the Scalenus muscle to such an extent that a ligature cannot be applied in that situa-
tion, it may be deemed advisable, as a last resource, to tie the first portion of the subclavian
artery. On the left side, this operation is quite impracticable ; the great depth of the artery
from the surface, its intimate relation with the pleura, and its close proximity with so many im-
portant veins and nerves, present a series of difficulties which it is impossible to overcome. On
the right side, the operation is practicable, and has been performed, though not with success.
The main objection to the operation in this situation is the smallness of the interval which usu-
ally exists between the commencement of the vessel, and the origin of the nearest branch.
This operation may be performed in the following manner. The patient being placed on a
table in the horizontal position, with the neck extended, an incision should be made parallel with
the inner part of the clavicle, and a second along the inner border of the Sterno-mastoid. meet-
ing it at right angles. The sternal attachment of the Sterno-mastoid may now be divided on a
director, and turned outwards ; a few small arteries and veins, and occasionally the anterior
jugular, must be avoided, and the Sterno-hyoid and Sterno-thyroid muscles divided in the same
manner as the preceding muscle. After tearing through the deep fascia with the finger-nail, the
internal jugular vein will be seen crossing the artery ; this should be pressed aside, and the artery
secured by passing the needle from below upwards, by which the pleura is more effectually avoided.
The exact position of the vagus nerve, the recurrent laryngeal, the phrenic and sympathetic
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 origin of the vessel. It should be remembered, that the right subclavian artery is occa-
sionally 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 ligation of the third part of the subclavian artery, the collate-
ral circulation is mainly established by three sets of vessels, as was described in a case of axillary
aneurism, in which Mr, Aston Key had tied the subclavian artery on the outer edge of the
Scalenus muscle, twelve years previously.1
" 1. A posterior set, consisting of the suprascapular and posterior scapular branches of the
subclavian, which anastomosed with the infrascapular from the axillary.
" 2. An internal set, produced by the connection of the internal mammary on the one hand,
with the short and long thoracic arteries, and the infrascapular, 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, to terminate either in the
main trunk, or some of the branches of the axillary, below. This last set presented most con-
spicuously the peculiar character of 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 infra-
scapular artery, which communicated most freely with the internal mammary, suprascapular, and
posterior scapular branches of the subclavian, from all of which it received so great an influx
of blood as to dilate it to three times its natural size."
Branches of the Subclavian Artery.
These are four in number. Three
arising from the first portion of the vessel,
the vertebra], the internal mammary, and
the thyroid axis ; and one from the second
portion, the superior intercostal. The
vertebral arises from the upper and back
part of the first portion of the arterj^ ; the
thyroid axis from the front, and the in-
ternal mammary from the under part of
this vessel. The superior intercostal is
given off from the upper and back part
of the second portion of the artery. On
the left side, the second portion usually
gives off no branch, the superior inter-
Fig. 215. — Plan of the Branches of the
Subclavian Artery.
Right
1 Guy's Hospital Reports, vol. i. 1836.
396 'ARTERIES.
costal arising at the inner side of the Scalenus anticus. 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 half an inch to an inch exist-
ing 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 existed, never
exceeding an inch and three-quarters. In a very few instances, the interval was
less than half an inch.
The Vertebral Artery (fig. 212) 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 upwards, enters the foramen in the transverse process of the
sixth cervical vertebra, and ascends through the foramina in the transverse processes
of all the vertebra? above this. Above the upper border of the axis, it inclines out-
wards and upwards to the foramen in the transverse process of the atlas, through
which it passes ; it then winds backwards behind its articular process, runs in a
deep groove on the surface of the posterior arch of this bone, and, piercing the
posterior occipito-atloid ligament and dura mater, enters the skull through the
foramen magnum. It then passes in front of the medulla oblongata, and unites
writh the vessel of the opposite side at the lower border of the pons Varolii, to
form the basilar artery.
At its origin, it is situated behind the internal jugular vein, and inferior thyroid
artery ; and, near the spine, lies between the Longus colli and Scalenus anticus
muscles, having the thoracic duct in front of it on the left side. Within the foramina
formed by the transverse processes of the vertebrae, it is accompanied by a plexus
of nerves from the sympathetic, and lies between the vertebral vein, which is in
front, and the cervical nerves, which issue from the intervertebral foramina behind
it. Whilst winding round the articular process of the atlas, it is contained in a
triangular space formed by the Rectus posticus minor, the Superior and Inferior
oblique muscles ; and it is covered by the Rectus posticus major and Complexus.
Within the skull, as it winds round the medulla oblongata, it is placed between
the hypoglossal and anterior root of the suboccipital nerves.
Branches. These may be divided into two sets, those given off in the neck, and
those within the cranium.
Cervical Branches. Cranial Branches.
Lateral spinal. Posterior meningeal.
Muscular. Anterior spinal.
Posterior spinal.
Inferior cerebellar.
The lateral spinal branches enter the spinal canal through the intervertebral
foramina, each dividing 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 spinal arteries ; the other is distributed to the posterior surface of the bodies
of the vertebrae.
Musctdar 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 deep cervical arteries.
The posterior meningeal are one or two small branches given off from the ver-
tebral opposite the foramen magnum. They ramify between the bone and dura
mater in the cerebellar fossa?, and supply the falx cerebelli.
The anterior spinal is a small branch, larger than the posterior spinal, which
arises near the termination of the vertebral, and unites with its fellow of the
opposite side in front of the medulla oblongata. The single trunk thus formed
descends a short distance on the front of the spinal cord, and joins with a
succession of small branches which enter the spinal canal through some of the
intervertebral foramina ; these branches are derived from the vertebral and ascend-
ing cervical, in the neck ; fronTthe intercostal, in the dorsal region ; and from the
VERTEBRAL. 397
xumbar, iliolumbar, and lateral sacral arteries in the lower part of the spine. They
unite, by means of ascending and descending branches, to form a single anterior
median artery, which extends as far as the lower part of the spinal cord. This
vessel is placed beneath the pia mater along the anterior median fissure ; it supplies
that membrane and the substance of the cord, and sends oft' branches at its lower
part, to be distributed to the cauda equina.
The posterior spinal arises from the vertebral, at the side of the medulla ob-
longata; passing backwards to the posterior aspect of the spinal cord, it descends
on either side, lying behind the posterior roots of the spinal nerves ; and is re-
inforced by a succession of small branches, which enter the spinal canal through
the intervertebral foramina, and by which it is continued to the lower part of the
cord, and to the cauda equina. Branches from these vessels form a free anastomosis
round the posterior roots of the spinal nerves, and communicate, by means of very
tortuous transverse branches, with the vessel of the opposite side. At its com-
mencement, it gives off an ascending branch, which terminates on the side of the
fourth ventricle.
The inferior cerebellar artery, the largest branch of the vertebral, winds back-
wards round the upper part of the medulla oblongata, passing between the origin
of the spinal accessory and pneumogastric nerves, over the restiform body, to the
under surface of the cerebellum, where it divides into two branches ; an internal
one, which is continued backwards to the notch between the two hemispheres of
the cerebellum ; and an external one, which supplies the under surface of the
cerebellum, as far as its outer border, where it anastomoses with the superior
cerebellar. Branches from this artery supply the choroid plexus of the fourth
ventricle.
The Basilar artery, 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 Varolii, where it divides
into two terminal branches, the posterior cerebral arteries. Its branches are, on
each side, the following: —
Transverse. Superior cerebellar.
Anterior cerebellar. Posterior cerebral.
The transverse branches supply the pons Varolii and adjacent parts of the
brain ; one accompanies the auditory nerve into the internal auditory meatus :
and another, of larger size, passes along the crus cerebelli, to be distributed to
the anterior border of the under surface of the cerebellum. It is called the
anterior (inferior) cerebellar artery.
The superior cerebellar arteries arise near the termination of the basilar. They
wind round the crus cerebri, close to the fourth nerve, and, arriving at the upper
surface of the cerebellum, divide into branches which supply the pia mater,
covering its surface, anastomosing with the inferior cerebellar. It gives several
branches to the pineal gland, and also to the velum interpositum.
The posterior cerebral arteries, the two terminal branches of the basilar, are
larger than the preceding, from which they are separated near their origin by the
third nerves. Winding round the crus cerebri, they pass to the under surface of
the posterior lobes of the cerebrum, which they supply, anastomosing with the
anterior and middle cerebral arteries. Near their origin, they give oft* numerous
branches, which enter the posterior perforated spot, and receive the posterior
communicating arteries from the internal carotid. They also give off a branch,
the posterior choroid, which supplies the velum interpositum and choroid plexus,
entering the interior of the brain, beneath the posterior border of the corpus
callosum.
Circle of Willis. The remarkable anastomosis which exists between the branches
of the internal carotid and vertebral arteries at the base of the brain, constitutes
the circle of "Willis. It is formed, in front, by the anterior cerebral and anterior
communicating arteries ; on each side, by the trunk of the internal carotid, and the
398 ARTERIES.
posterior communicating ; behind, by the posterior cerebral, and point of the basilar
It is by this anastomosis that the cerebral circulation is equalized, 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 lamina cinerea,
the commissure of the optic nerves, the infundibulum, the tuber cinereum, the
corpora albicantia, and the pars perforata postica.
The Thyroid Axis is a short, thick trunk, which arises from the fore part of
the first portion of the subclavian artery, close to the inner side of the Scalenus
anticus muscle, and divides, almost immediately after its origin, into three
branches, the inferior thyroid, suprascapular, and transversalis colli.
The Inferior Thyroid Artery passes upwards, in a serpentine course, behind
the sheath of the common carotid vessel and sympathetic nerve (the middle
cervical ganglion resting upon it), and is distributed to the under surface of the
thyroid gland, anastomosing with the superior thyroid, and with the correspond-
ing artery of the opposite side. Its branches are the
Laryngeal. (Esophageal.
Tracheal. Ascending cervical.
The laryngeal branch ascends upon the trachea to the back part of the larynx,
and supplies the muscles and the mucous membrane of this part.
The tracheal branches are distributed upon the trachea, anastomosing below
with the bronchial arteries.
The esophageal branches are distributed to the oesophagus.
The ascending cervical is a small branch which arises from the inferior thyroid,
just where that vessel is passing behind the common carotid artery, and runs up
the neck in the interval between the Scalenus anticus and Rectus anticus major.
It gives branches to the muscles of the neck, which communicate with those sent
out from the vertebral, and sends one or two through the intervertebral foramina,
along the cervical nerves, to supply the bodies of the vertebrae, the spinal cord,
and its membranes.
The Suprascapular Artery, smaller than the transversalis colli, passes
obliquely from within outwards, across the root of the neck. It at first lies on
the lower part of the Scalenus anticus, being covered by the Sterno-mastoid ; it
then crosses the subclavian artery, and runs outwards 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 to the supra-spinous fossa. In this situation it lies close
to the bone, and ramifies between it and the Supra-spinatus muscle to which it is,
mainly distributed, giving off a communicating branch, which crosses the neck of
the scapula, to reach the infra-spinous fossa, where it anastomoses with the dorsal
branch of the subscapular artery. Besides distributing branches to the Sterno-
mastoid, and neighboring muscles, it gives off" a supra-acromial branch, which,
piercing the Trapezius muscle, supplies the cutaneous surface of the acromion,
anastomosing with the acromial thoracic artery. As the artery passes across the
suprascapular notch, a branch descends into the subscapular fossa, ramifies
beneath that muscle, and anastomoses with the posterior and subscapular arteries.
It also supplies the shoulder-joint.
The Transversalis Colli passes transversely outwards, across the upper part 01'
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 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 ascends beneath the anterior margin of the Trapezius,
distributing branches to it, and to the neighboring muscles and glands in the
neck.
INTERNAL MAMMARY.
399
The posterior scapular, the continuation of the transversalis colli, passes beneath
the Levator anguli scapulas to the superior angle of the scapula, and descends
along the posterior border of that bone as far as the inferior angle, where it anas-
tomoses with the subscapular branch of the axillary. In its course it is covered
Fig. 216. — The Scapular and Circumflex Arteries.
Better it r Srafia/ar
ial Brarrb
by the Rhomboid muscles, supplying these, 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 Internal Mammary arises from the under surface of the first portion of
the subclavian artery, opposite the thyroid axis. It descends behind the clavicle,
to the inner surface of the anterior wall of the chest, resting upon the costal
cartilages, a short distance from the margin of the sternum ; and, at the interval
between the sixth and seventh cartilages, divides into two branches, the musculo-
phrenic, and superior epigastric.
At its origin, it is covered by the internal jugular and subclavian veins, and
crossed by the phrenic nerve. In the upper part of the thorax, it lies upon the
costal cartilages, and Internal intercostal muscles in front, covered by the pleura
behind. At the lower part of the thorax, the Triangularis sterni separates this
vessel from the pleura. It is accompanied by two veins, which join at the upper
part of the thorax into a single trunk.
The branches of the internal mammary are the
Comes nervi phrenici or Superior phrenic.
Mediastinal.
Pericardiac.
Sternal.
Anterior intercostal.
Perforating.
Musculo-phrenic.
Superior epigastric.
The comes nervi phrenici or superior phrenic is a long slender branch, which
accompanies the phrenic nerve, between the pleura and pericardium, to the Dia-
phragm, to which it is distributed ; anastomosing with the other phrenic arteries
from the internal mammary, and abdominal aorta.
400 ARTERIES.
The mediastinal branches are small vessels, which are distributed to the areolar
tissue in the anterior mediastinum, and the remains of the thymus gland.
The pericardiac branches supply the upper part, of the pericardium, the lower
part receiving branches from the musculo-phrenic artery. Some sternal branches
are distributed to the Triangularis sterni, and both surfaces of the sternum.
The anterior intercostal arteries supply the five or six upper intercostal spaces.
The branch corresponding to each space passes outwards, and soon divides into
two, which run along the opposite borders of the ribs, and inosculate with the
intercostal arteries from the aorta. They are at first situated between the pleura
and the Internal intercostal muscles, and then between the two layers of these
muscles. They supply the Intercostal and Pectoral muscles, and the mammary
gland.
The anterior or perforating arteries correspond to the five or six upper inter-
costal spaces. They arise from the internal mammary, pass forwards through the
intercostal spaces, and, curving outwards, supply the Pectoralis major, and the
integument. Those which correspond to the first three spaces are distributed to
the mammary gland. In females, during lactation, these branches are of large
size.
The musculo-phrenic artery is directed obliquely downwards and outwards, behind
the cartilages of the false ribs, perforating the Diaphragm 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 ; they diminish in size as the spaces decrease in length, and
are distributed in a manner precisely similar to the anterior intercostals from the
internal mammary. It also gives branches backwards to the Diaphragm, and
downwards to the abdominal muscles.
The superior epigastric continues in the original direction of the internal mam-
mary, descends behind the Rectus muscle, and, perforating its sheath, divides into
branches which supply the Rectus, anastomosing with the epigastric artery from
the external iliac. Some vessels perforate the sheath of the Rectus, and supply
the muscles of the abdomen and the integument, and a small branch, which passes
inwards upon the side of the ensiform appendix, anastomoses in front of that
cartilage with the artery of the opposite side.
The Superior Intercostal arises from the upper and back part of the sub-
clavian artery, beneath the anterior scalenus on the right side, and to the inner side
of the muscle on the left side. Passing backwards, 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. In the first intercostal space,
it gives off a branch which is distributed in a similar manner with the aortic
intercostals. The branch for the second intercostal space usually joins with one
from the first aortic intercostal. Each intercostal gives off a branch to the posterior
spinal muscles, and a small one, which passes through the corresponding inter-
vertebral foramen to the spinal cord and its membranes.
The deep cervical branch [profunda cervicis) arises, in most cases, from the superior
intercostal, and is analogous to the posterior branch of an aortic intercostal artery.
Passing backwards, between the transverse process of the seventh cervical vertebra
and the first rib, it ascends the back part of the neck, between the Complexus
and Semi-spinalis colli muscles, as high as the axis, supplying these and adjacent
muscles, and anastomosing with the arteria princeps cervicis of the occipital, and
with branches which pass outwards from the vertebral.
OF THE AXILLA.
401
Surgical Anatomy of the Axilla.
The Axilla is a conical space, situated between the upper and lateral parts of
the chest, and inner side of the arm.
Boundaries. Its apex, which is directed upwards towards the root of the neck,
corresponds to the interval between the first rib internally, the superior border of
the scapula externally, and the clavicle and Subclavius muscle in front. The base,
directed downwards, is formed by the integument, and a thick layer of fascia,
extending between the lower border of the Pectoralis major in front, and the lower
border of the Latissimus dorsi behind ; it is broad internally, at the chest, but
narrow and pointed externally, at the arm. Its anterior boundary is formed by
the Pectoralis major and Pectoralis minor muscles, the former covering the whole of
Fig. 217. — The Axillary Artery and its Branches.
the anterior wall of the axilla, the latter covering only its central part. Its posterior
boundary, which extends somewhat lower than the anterior, is formed by the Sub-
scapulars above, the Teres major and Latissimus dorsi below. On the inner side
are the first four ribs and their corresponding Intercostal muscles, and part of the
Serratus magnus. 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 nerve?
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.
26
402 ARTERIES.
Tlieir Position. 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 altogether concealing it.
At the fore part of the axillary space, in contact with the Pectoral muscles, are
the thoracic branches of the axillary artery, and, along the anterior margin of the
axilla, 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 sub-
scapular vessels and nerves ; winding around the lower border of this muscle, are
the dorsalis scapulee artery and veins ; and towards the outer extremity of the
muscle, the posterior circumflex vessels and nerve are seen curving backwards to
the shoulder.
Along the inner or thoracic side, no vessel of any importance exists, its upper
part being crossed by a few small branches from the superior thoracic artery.
There are some important nerves, however, in this situation ; the posterior 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, are the intercosto-humeral nerves, which pass across the axilla to the inner
side of the arm.
The cavity of the axilla is filled by a quantity of loose areolar tissue, a large
number of small arteries and veins, all of which are, however, of inconsiderable
size, and numerous lymphatic glands ; these are from ten to twelve in number,
and situated chiefly on the thoracic side, and lower and back part of this space.
The student should attentively consider the relation of the vessels and nerves
in the several parts of the axilla ; for it not unfrequently happens, that the sur-
geon is called upon to extirpate diseased glands, or to remove a tumor from this
situation. 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, as here the
axillary vessels will be in danger of being wounded. Towards the posterior wall,
it will be necessary to avoid the subscapular, dorsalis scapulae, and posterior
circumflex vessels, and, along the anterior wall, the thoracic branches. It is only
along the inner or thoracic wall,' and in the centre of the axillary cavity, that
there are no vessels of any importance; a most fortunate circumstance, for it
is in this situation more especially that tumors requiring removal are most fre-
quently situated.
The Axillary Artery.
The axillary artery, the continuation of the subclavian, commences at the lower
border of the first rib, and terminates at the lower border of the tendons of the
Latissimus dorsi and Teres major muscles, when it becomes the 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 upwards and out-
wards ; when it is directed at right angles with the trunk, the vessel is nearly
straight ; and if elevated still higher, it describes a curve, the concavity of which
is directed upwards. At its commencement the artery is very deeply situated,
but near its termination is superficial, being covered only by the skin and fascia.
The description of the relations of this vessel may be facilitated by its division
into three portions ; the first portion being that above the Pectoralis minor, the
second portion beneath, and the third, below, that muscle.
The first portion of the axillary artery is in relation, in front, with the clavicular
portion of the Pectoralis major, the costo-coracoid membrane, and the cephalic
vein ; behind, with the first intercostal space, the corresponding Intercostal muscle,
the first serration of the Serratus magnus, and the posterior thoracic nerve;
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.
AXILLARY. 403
Relations of First Portion of the Axillary Artery.
In front.
Pectoralis major.
Costo-coracoid membrane.
Cephalic vein.
Order side. I Axillary \ Inner side.
Brachial plexus. I HrBtportton. J Axillary vein.
Behind.
First intercostal space, and Intercostal muscle.
First serration of Serratus magnus.
Posterior thoracic nerve.
The second portion of the axillary artery lies beneath the Pectoralis minor. It
is covered, in front, by the Pectoralis major and Pectoralis minor muscles; behind^
it is separated from the Subscapulars by a cellular interval ; on the inner side, it is
in contact with the axillary vein. The brachial plexus of nerves surrounds the
artery, and separates it from direct contact with the vein and adjacent muscles.
Relations of Second Portion of the Axillary Artery.
In front.
Pectoralis major and Pectoralis minor.
Outer side. I %$£? \ Inner side.
Brachial plexus. Isecoiid portion.) Axillary vein.
Behind.
Subscapularis.
The third portion of the axillary artery lies below the Pectoralis minor. It is
in relation, in front, with the lower border of the Pectoralis major above, being
covered only by the integument and fascia below ; behind, with the lower part of
the Subscapularis, and the tendons of the Latissimus dorsi and Teres major ; on
its outer side, with the Coraco-brachialis ; on its inner or thoracic side, with the
axillary vein. The brachial plexus of nerves bears the following relation to the
artery in this part of its course ; on the outer side are the median nerve, and the
musculo-cutaneous for a short distance ; on the inner side, the ulnar, the internal, and
lesser internal cutaneous nerves ; and behind, the musculo-spiral and circumflex,
the latter extending only to the lower border of the Subscapularis muscle.
Relations of Third Portion of the Axillary Artery.
In front.
Integument and fascia.
Pectoralis major.
Outer side. f \ Inner side.
Coraco-brachialis. | briery7 j Ulnar nerve.
Median nerve. \ Third portion./ Internal cutaneous nerr 33.
Musculo-cutaneous nerve. \ / Axillary vein.
Behind.
Subscapularis.
Tendons of Latissimus dorsi and Teres major.
Musculo-spiral, and circumflex nerves.
404 ARTERIES.
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 gave
origin to the subscapular, circumflex, and profunda arteries of the arm. Sometimes 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.
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 this vessel is 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 ; on compressing it in this situation from within outwards upon the
humerus, the circulation may be effectually suspended.
The application of a ligature to the axillary artery may be required in cases of aneurism of
the upper part of the brachial ; and there are only two situations in which it may be secured,
viz., in the upper, or in the lower part of its course ; for the axillary artery at its central part is
«o deeply seated, and, at the same time, so closely surrounded with large nervous trunks, that the
application of a ligature to it in this situation would be almost impracticable.
In the lower part of its course, the operation is more 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, the head of the humerus is felt for, and an incision made through the integu-
ment over it, about two inches in length, 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 these 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 derived from
the Latissimus dorsi, which may mislead the surgeon during an operation. It may easily be
recognized by the transverse direction of its fibres (see p. 272).
The upper portion of the axillary artery may be tied, in cases of aneurism encroaching so
far upwards 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
attended with much difficulty and danger. The student will remark, that in this situation it
would be necessary to divide a thick muscle, and, after separating the costo-coracoid mem-
brane, the artery would be exposed at the bottom of a more or less deep space, with the cepha-
lic and axillary 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.
In a case of wound of this vessel the general practice of cutting down upon it, and tying it
above and below the wounded point, should be adopted in all cases.
The branches of1 the axillary artery are
From 1st Part. J Superior thoracic.
( Acromial thoracic.
From 2d Part. J Thoracica longa.
( Thoracica alaris.
I Subscapular.
From 3d Part. < Anterior circumflex.
( Posterior circumflex.
The superior thoracic is a small artery, which arises from the axillary, or by a
common trunk with the acromial thoracic. Running forwards and inwards along
the upper border of the Pectoralis minor, it passes between it and the Pectoralis
major to the side of the chest. It supplies these muscles, and the parietes of the
thorax, anastomosing with the internal mammary and intercostal arteries.
The acromial thoracic is a short trunk, which arises from the fore part of the
axillary artery. Projecting forwards to the upper border of the Pectoralis minor,
it divides into three sets of branches, thoracic, acromial, and descending. The
thoracic branches, two or three in number, are distributed to the Serratus magnus
and Pectoral muscles, anastomosing with the intercostal branches of the internal
AXILLARY— BRACHIAL. 405
mammary. The acromial branches are directed outwards towards the acromion,
supplying the Deltoid muscle, and anastomosing, on the surface of the acromion,
with the suprascapular and posterior circumflex arteries. The descending branch
passes in the interspace between the Pectoralis major and Deltoid, accompanying
the cephalic vein, and supplying both muscles.
The thoracica longa passes downwards and inwards 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 Subscapularis, which anastomose with the internal mam-
mary and intercostal arteries.
The thoracica alaris 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, the largest branch of the axillary artery, arises opposite the
lower border of the Subscapularis muscle, and passes downwards and backwards
along its lower margin to the inferior angle of the scapula, where it anastomoses
with the posterior scapular, a branch of the subclavian. It distributes branches to
the Subscapularis, Serratus magnus, Teres major, and Latissimus dorsi muscles,
and gives off, about an inch and a-half from its origin, a large branch, the dorsalis
scapulae. This vessel curves round the inferior border of the scapula, leaving the
axilla in the interspace between the Teres minor above, the Teres major below,
and the long head of the Triceps in front ; and divides into three branches, a sub-
scapular, which enters the subscapular fossa beneath the Subscapularis which it
supplies, anastomosing with the subscapular and suprascapular arteries ; an infra-
spinous branch (dorsalis scapulas), which turns round the axillary border of the
scapula, between the Teres minor and the bone, enters the infra-spinous fossa,
supplies the Infra-spinatus muscle, and anastomoses with the suprascapular and
posterior scapular arteries ; and a median branch, which 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, anastomoses with the supra-
scapular.
The circumflex arteries wind round the neck of the humerus.
The posterior circumflex, the larger of the two, arises from the back part of
the axillary, opposite the lower border of the Subscapularis muscle, and, passing
backwards with the circumflex veins and nerve, through the quadrangular space
bounded by the Teres major and Teres minor, the scapular head of the Triceps and
the humerus, winds round the neck of that bone, is distributed to the Deltoid muscle
and shoulder-joint, anastomosing with the anterior circumflex, suprascapular, and
acromial thoracic arteries.
The anterior circumflex, considerably smaller than the preceding, arises just
below that vessel, from the outer side of the axillary artery. It passes horizontally
outwards, beneath the Coraco-brachialis and short head of the Biceps, lying upon
the fore part of the neck of the humerus, and, on reaching the bicipital groove,
gives off an ascending branch, which passes upwards along it, to supply the head
of the bone and the shoulder-joint. The trunk of the vessel is then continued
•outwards beneath the Deltoid which it supplies, and anastomoses with the posterior
circumflex and acromial thoracic arteries.
Brachial Artery (fig. 218).
The brachial artery 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.
The direction of this vessel is marked by a line drawn from the outer side of
the axillary space between the folds of the axilla, to a point midway between the
406
ARTERIES.
Fig. 218.— The Surgical
Jtirrv*
Anatomy of the Brachial Artery, condyles of the humerus, which
corresponds to the depression along
the inner border of the Coraco-
brachial! s and Biceps muscles. In
the upper part of its course, this
vessel lies internal to the humerus ;
but below, it is in front of that
bone.
Relations. This artery is super-
ficial throughout its entire extent,
being covered, in front, by the in-
tegument, the superficial and deep
fasciae ; the bicipital fascia separates
it opposite the elbow from the me-
dian basilic vein ; the median nerve
crosses it at its centre ; and the basilic
vein lies in the line of the artery,
but separated from it by the fascia,
in the lower half of its course.
Behind, it is separated from the
inner side of the humerus above,
by the long and inner heads of the
Triceps, the musculo- spiral nerve
and superior profunda artery inter-
vening ; and from the front of the
bone below, by the insertion of the
Coraco-brachialis and the Brachialis
anticus muscles. By its outer side,
it is in relation with the commence-
ment of the median nerve, and
the Coraco-brachialis and Biceps
muscles, which slightly overlap the
artery. By its inner side, with the
internal cutaneous and ulnar nerves,
its upper half; the median nerve,
its lower half. It is accompanied
by two veins, the venae comites;
they lie in close contact with the
artery, being connected together
at intervals by short transverse
communicating branches.
Aniaatomo ticct
Plan of the Kelations of the Brachial Artery.
In front.
Integument and fascia?.
Bicipital fascia, median basilic vein.
Median nerve.
Outer side.
Median nerve.
Coraco-brachialis.
Biceps.
Inner side.
Internal cutaneous.
Ulnar and median nervea.
Behind.
Triceps.
Musculo-spiral nerve.
Superior profunda artery.
Coraco-brachialis.
Brachialis anticus.
BRACHIAL. 407
Bexd of the Elbow.
At the bend of the elbow, the brachial artery sinks deeply into a triangular
interval, the base of which is directed upwards towards the humerus, and the sides
of which are bounded, externally, by the Supinator longus ; internally, by 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 coronoid process of the ulna 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, but is
separated from it below by an interval of half an inch. The tendon of the Biceps
lies to the outer side of the space, and the musculo-spiral nerve still more
externally, lying upon the Supinator brevis, and partly concealed by the Supinator
longus.
Peculiarities of the Artery as regards its Course. The brachial artery, accompanied by the
median nerve, may leave the inner border of the Biceps, and descend towards the inner condyle
of the humerus, where it usually curves round a prominence of bone, to which it is connected by
a fibrous band ; it then inclines outwards, beneath or through the substance of the Pronator teres
muscle, to the bend of the elbow. This variation bears considerable analogy with the normal
condition of the artery in some of the carnivora (see p. 131).
Peculiarities 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 th» usual point, the former condition being
by far the most 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 90 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.
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 division of the radial. It 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 perfo-
rate the fascia, and pass over the artery, immediately beneath the integument.
The ulnar sometimes arises from the brachial high up, and then occasionally leaves that vessel
at the lower part of the arm, and descends towards the inner condyle. In the forearm, it gene-
rally 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 descends the arm, it lies behind the main trunk, and at the bend of the elbow regains its usual
position.
In some cases of high division of the radial, the remaining trunk (ulnar interosseous) occasion-
ally passes, together with the median nerve, along the inner margin of the arm to the inner con-
dyle, and then passing from within outwards, beneath or through the Pronator teres, regains its
usual position at the end 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.
408 ARTERIES.
Varieties in 3Iuscular Relations} The brachial artery is occasionally concealed, in some part
of its course, by muscular or tendinous slips derived from various sources. In the upper third
of the arm, the brachial vessels and median nerve have been seen concealed to the extent of
three inches by a muscular layer of considerable thickness, derived from the Coraco-brachialis,
which passed round to the inner side of the vessel, and joined the internal head of the Triceps.
In the lower half of the arm it is occasionally concealed by a broad thin head to the Biceps
muscle (see p. 303). A narrow fleshy slip from the Biceps has been seen to cross the artery,
concealing it for an inch and a half, its tendon ending in the aponeurosis covering the Pronator
teres. A muscular and tendinous slip has been seen to arise from the external bicipital ridge
by a long tendon, cross obliquely behind the long tendon of the Biceps, end in a fleshy belly,
which appears on the inner side of the arm between the Biceps and Coraco-brachialis. passes
down along the inner edge of the former, and crosses the artery very obliquely, so as to lie in
front of it for three inches, and, finally, end in a narrow flattened tendon, which is inserted into
the aponeurosis over the Pronator teres. A tendinous slip, arising from the deep part of the
tendon of the Pectoralis major, has been seen to cross the artery obliquely at or below the
Coraco-brachialis, and join the intermuscular septum above the inner condyle. The Brachialis
anticus not unfrequently projects at the outer side of the artery, occasionally overlaps it, sending
inwards, across the artery, an aponeurosis which binds the vessel down upon the Brachialis
anticus. Sometimes a fleshy slip from the muscle covers the vessel, in one case, to the extent
of three inches. In some cases of high origin of the Pronator radii teres, an aponeurosis extends
from it to join the Brachialis anticus external to the artery; a kind of arch being thus formed,
under which the principal artery and median nerve pass, so as to be concealed for half an inch
above the transverse level of the condyle.
Surgical Anatomy. Compression of the brachial artery is required in cases of amputation of
the arm or forearm, in resection of the elbow-joint, and the removal of tumors ; and it will be
observed, that it may be effected in almost any part of its course ; if pressure is made in the upper
part of the limb it should be directed from within outwards, and if in the lower part from before
backwards, as the artery lies on the inner side of the humerus above, and in front of it below.
The most favorable situation is either above or below the insertion of the Coraco-brachialis.
The application of a ligature to the brachial artery may be required in cases of wounds of the
vessel, or in wounds of the palmar arch, where compression of the radial and ulnar arteries fails to
arrest the hemorrhage. It is also necessary in cases of aneurism of the brachial, the radial, ulnar,
or interosseous arteries; and it may be secured in any part of its course. The chief guides in
determining its position are the surface-markings produced by the inner margin of the Coraco-
brachialis and Biceps, the known course of the vessel, and its pulsation, which should be care-
fully 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
divided across, in order to expose the vessel.
In the upper third <f the arm the artery maybe exposed in the following manner: — The patient
being placed horizontally 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 ulnar 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 run on the surface of the artery as high
as the axilla. 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 vena? 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 ulnar to the radial 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 ascertain,
by alternately pressing on one or the other 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
towards the inner condyle of the humerus, or in its usual position, but deeply placed beneath the
common trunk: a knowledge of these facts will at once suggest the precautions necessary in
every case, and indicate the necessary measures to be adopted when 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
tying upon the artery, sometimes beneath ; this being drawn inwards and the muscle outwards,
1 Stbuther's Anatomical and Physiological Observations.
SURGICAL ANATOMY OF BRACHIAL ARTERY. 409
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
towards the Biceps rather than inwards or backwards towards the Triceps.
The lower part of the brachial artery is of extreme interest in a surgical point of view, on ac-
count of the relation which it bears to those 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 in no case should
this vessel be selected for venesection, except in a part which is not in contact with 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 subscapular
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
profundae, 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."
The branches of the brachial artery are the
Superior profunda. Inferior profunda.
Nutrient artery. Anastomotica magna.
Muscular.
The superior profunda arises from the inner and back part of the brachial,
opposite the lower border of the Teres major, and passes backwards to the
interval between the outer and inner heads of the Triceps muscle, accompanied
by the musculo-spiral nerve ; it winds round the back part of the shaft of the
humerus in the spiral groove, between the Triceps and the bone, and descends on
the outer side of the arm to the space between the Brachialis anticus and
Supinator longus, as far as the elbow, where it anastomoses with the recurrent
branch of the radial artery. It supplies the Deltoid, Coraco-brachialis, and
Triceps muscles, and whilst in the groove, between the Triceps and the bone, it
gives off the posterior articular artery, which descends perpendicularly between
the Triceps and the bone, to the back part of the elbow-joint, where it anastomo-
ses with the interosseous recurrent branch, and, on the inner side of the arm,
with the posterior ulnar recurrent, and with the anastomotica magna or inferior
profunda (fig. 221).
The nutrient artery of the shaft of the humerus arises from the brachial, about
the middle of the arm. Passing downwards, it enters the nutritious canal of that
bone, near the insertion of the Coraco-brachialis muscle.
The inferior profunda, of small size, arises from the brachial, a little below the
middle of the arm ; piercing the internal intermuscular septum, it descends on the
surface of the inner head of the Triceps muscle, to the space between the inner
condyle and olecranon, accompanied by the ulnar nerve, and terminates by anas-
tomosing with the posterior ulnar recurrent, and anastomotica magna.
The anastomotica magna arises from the brachial, about two inches above the
elbow-joint. It passes transversely inwards upon the Brachialis anticus, and,
piercing the internal intermuscular septum, winds round the back part of the
humerus, between the Triceps and the bone, forming an arch above the olecranon
fossa, by its junction with the posterior articular branch of the superior profunda.
As this vessel lies on the Brachialis anticus, an offset passes between the internal
condyle and olecranon, which anastomoses with the inferior profunda and pos-
terior ulnar recurrent arteries. Other branches ascend to join the inferior pro-
funda ; and some descend in front of the inner condyle, to anastomose with the
anterior ulnar recurrent.
The muscular are three or four large branches, which are distributed to the
1 Chelins's Surgery, p. 254.
410
ARTERIES.
muscles in the course of the artery. They supply the Coraco-brachialis, Biceps,
and Brachialis anticus muscles.
Fig. 219. — The Surgical Anatomy of the Radial and Ulnar
Arteries.
J!jrli<il Seoarrr-nt.
JDmOP k-rancA if Ulnar
Superficial)* Vila
Radial Artery.
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 back-
wards, round the outer side
of the carpus, beneath the
Extensor tendons of the
thumb, and, running forwards,
passes between the two heads
of the first Dorsal interos-
seous muscle, into the palm
of the hand. It then crosses
the metacarpal bones to the
ulnar border of the hand,
forming the deep palmar arch,
and, at its termination, inos-
culates with the deep branch
of the ulnar artery. The
relations of this vessel may
thus be conveniently divided
into three parts, viz., in front
of the forearm, at the back
of the wrist, and in the hand.
Relations. In the forearm,
this vessel extends from op-
posite the neck of the radius,
to the fore part of the styloid
process, being placed to the
inner side of the shaft of that
bone above, and in front of it
below. It is superficial
throughout its entire extent,
being covered by the integu-
ment, the superficial and
deep fasciae, and slightly
overlapped above by the
Supinator longus. In its
course downwards it lies
upon the tendon of the Bi-
ceps, the Supinator brevis,
the Pronator radii teres, radial
origin of the Flexor sublimis
digitorum, the Flexor longus
pollicis, Pronator quadratus,
and the lower extremity of
the radius. In the upper
RADIAL. 411
third of its course, it lies between the Supinator longus and the Pronator radii
teres ; in its lower two-thirds, between the tendons of the Supinator longus and
the Flexor carpi radialis. The radial nerve lies along the outer side of the artery,
in the middle third of its course ; and some filaments of the musculocutaneous
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 vense comites throughout
its whole course.
Plan of the Relations of the Radial Artery in the Forearm.
In front.
Integument, superficial and deep fasciae.
Supinator longus.
Inner side. /^ ~\ Outer side.
Pronator radii teres. f \ Supinator longus.
Flexor carpi radialis. / Arteryin \ Badial nerve (middle
third).
Behind.
Tendon of Biceps.
Supinator brevis.
Pronator radii teres.
Flexor sublimis digitorum.
Flexor longus pollicis.
Pronator quadratus.
Badius.
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,
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, transversely across the palm, to the base of
the metacarpal bone of the little finger, where it inosculates with the communi-
cating branch from the ulnar artery, forming the deep palmar arch. It lies upon
the carpal extremities of the metacarpal bones and the Interossei muscles, being
covered by the Flexor tendons of the fingers, the Lumbricales, the muscles of the
little finger, and the Flexor brevis pollicis, and is accompanied by the deep branch
of the ulnar nerve.
Peculiarities. The origin of the radial artery varies nearly in the proportion of one case in
eight. In one case the origin was lower than usual; in the others, the upper part of the
brachial was a more frequent source of origin than the axillary. 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 frequently 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 along its inner border ; and in turning round the wrist, it has been
seen lying over, instead of beneath, the Extensor tendons.
Surgical Anatomy. 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 easily exposed in any part of its course through the forearm. The operation in
the middle or inferior third of this region is easily performed ; but in the upper third, near the
elbow, the operation is attended with some difficulty, from the greater depth of the vessel, and
from its being overlapped by the Supinator longus and Pronator radii teres muscles.
To tie the artery in this situation, an incision three inches in length should be made through
the integument, from the bend of the elbow obliquely downwards and outwards, on the radial
side of the forearm, avoiding the branches of the median vein; the fascia of the arm being
412
ARTERIES.
divided, and the Supinator longus drawn a little outwards, the artery will be exposed. The
vena; 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 fasciae in the
interval between the tendons of the Supinator Longus and Flexor carpi radialis muscles.
The branches of the radial artery may be divided into three groups, correspond-
ing with the three regions in which this vessel is situated.
In the
Forearm.
Radial recurrent.
Muscular.
Superficialis volse.
Anterior carpal.
Hand.
Wrist.
Princeps pollicis.
Radialis indicis.
Perforantes.
Interossese.
I Dorsales pollicis.
[_ Dorsalis indicis.
Posterior carpal.
j Metacarpal.
The radial recurrent is given off' immediately 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, the elbow-joint, and anastomosing with the terminal branches of the
superior profunda.
The muscular branches are distributed to the muscles on the radial side of the
forearm.
The superficialis volse arises from the radial artery, just where this vessel is
about to wind round the wrist. Running forwards, it passes between the muscles
of the thumb, which it supplies, and anastomoses with the termination of the ulnar
artery, completing the superficial palmar arch. This vessel varies considerably
in size, usually being very small, and terminating in the muscles of the thumb ;
sometimes it is as large as the continuation of the radial.
The carpal branches supply the joints of the wrist. The anterior carpal is a
small vessel which arises from the radial artery near the lower border of the Pro-
nator quadratus, and, running inwards in front of the radius, anastomoses with the
anterior carpal branch of the ulnar artery. From the arch thus formed, branches
descend to supply the articulations of the wrist.
The posterior carpal 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.
It sends branches upwards, which anastomose with the termination of the ante-
rior interosseous artery ; other branches descend to the metacarpal spaces ; they
are the dorsal interosseous arteries for the third and fourth interosseous spaces,
and anastomose with the posterior perforating branches from the deep palmar
arch.
The metacarpal {first dorsal interosseous brayich) arises beneath the Extensor
tendons of the thumb, sometimes with the posterior carpal artery, running for-
wards on the second Dorsal interosseous muscle ; communicating, behind, with
the corresponding perforating branch % of the deep palmar arch; and, in front,
inosculating with the digital branch of the superficial palmar arch, and supplying
the adjoining sides of the index and middle fingers.
The dorsales pollicis are two small vessels which run along the sides of the
dorsal aspect of the thumb. They sometimes arise separately, or occasionally by
a common trunk, near the base of the first metacarpal bone.
The dorsalis indicis, also a small branch, runs along the radial side of the back
of the index finger, sending a few branches to the Abductor indicis.
BRANCHES OP THE RADIAL.
413
The princeps pollicis arises from the radial just as it turns inwards to the deep
part of jthe hand ; it descends between the Abductor indicis and Adductor pollicis,
along the ulnar side of the meta-
Fig. 220. — Ulnar and Radial Arteries.
Deep View.
Axbiior Ylnar
Recurrent
Fosftricr Vlnar
llerurrtiit
carpal 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 under surface of the
last phalanx, from which branches
are distributed to the integument
and cellular membrane of the thumb.
The radialis indicis arises close
to the preceding, descends between
the Abductor indicis and Adductor
pollicis, and runs along the radial
side of the index-finger to its ex-
tremity, where it anastomoses with
the collateral digital artery from the
superficial palmar arch. At the
lower border of the Adductor
pollicis this vessel anastomoses with
the princeps pollicis, and gives a
communicating branch to the super-
ficial palmar arch.
The perforantes, three in number,
pass backwards between the heads
of the last three Dorsal interossei
muscles, to inosculate with the dor-
sal interosseous arteries.
The palmar inter ossese, three or
four in number, are branches of the
deep palmar arch ; they run for-
wards upon the Interossei muscles,
and anastomose at the clefts of the
fingers with the digital branches of
the superficial arch.
Ulnar Artery.
The Ulnar Artery, the larger of
the two subdivisions of the bra-
chial, commences a little below the
bend of the elbow, and crosses the
inner side of the forearm obliquely
to the commencement of its lower
half; it then runs along its ulnar
border to the wrist, crosses the annu-
lar ligament on the radial side of the
pisiform bone and passes across the palm of the hand, forming the superficial
palmar arch, which terminates by inosculating with the superficialis voice.
Relations in the Forearm. In its upper half, it is deeply seated, being covered
by all the superficial Flexor muscles, excepting the Flexor carpi ulnaris ; crossed
by the median nerve, which, for about an inch lies to its inner side ; and 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, and the superficial and deep fasciae, and is placed between the Flexor
414
ARTERIES.
carpi ulnaris and Flexor sublimis digitorum muscles. It is accompanied by two
veins, which lie one on each side of the vessel ; the ulnar nerve lies on its inner
side for the lower two-thirds of its extent, and a small branch from it 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.
MeT™.eMr m°SClCS' } UPPer Wf .r the arte^.
Superficial and deep fasciee. Lower half of the artery.
Inner side.
Flexor carpi ulnaris.
Ulnar nerve (lower two-thirds of
the artery.)
Outer side.
Flexor sublimis digitorum.
Behind.
Brachialis anticus.
Flexor profundus digitorum.
At the wrist, 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.
In the palm of the hand, the continuation of the ulnar artery is called the super-
ficial palmar arch ; it passes obliquely outwards to the interspace between the
ball of the thumb and the index-finger, where it anastomoses with the superficialis
volae, and a branch from the radialis indicis, thus completing the superficial pal-
mar arch. The convexity of this arch is directed towards the fingers, its concav-
ity towards the muscles of the thumb.
The superficial palmar arch is covered by the Palmaris brevis, the palmar fascia,
and integument ; and lies upon the annular ligament, the muscles of the little finger,
the tendons of the superficial Flexor, and the divisions of the median and ulnar
nerves, the latter accompanying the artery a short part of its course.
Relations of the Superficial Palmar Arch.
In front.
Integument.
Palmaris brevis.
Palmar fascia.
Behind.
Annular ligament.
Origin of muscles of little finger.
Superficial Flexor tendons.
Divisions of median and ulnar nerves.
Peculiarities. The ulnar artery was found to vary in its origin nearly in the proportion of
one in thirteen cases, in one case arising lower than usual, about two or three inches below the
elbow, and in all the other cases much higher, the brachial being a more frequent source of origin
than the axillary.
Variations in the position of this vessel are more frequent than in the radial. When its ori-
gin is normal, the course of the vessel is rarely changed. When it arises high up, its position
id the forearm is almost invariably superficial to the Flexor muscles, lying commonly beneath the
fascia, more rarely between the fascia and integument. In a few cases, its position was subcu-
taneous in the upper part of the forearm, sub-aponeurotic in the lower part.
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 their division would
be requisite in a case of recent wound of the artery in this situation, in order to secure it, but
under no other circumstances. 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 venae
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 OF THE ULNAR.
415
The branches of the ulnar artery may be arranged into the following groups : —
( Anterior ulnar recurrent.
Posterior ulnar recurrent.
Forearm. \ T '. \ Anterior interosseous.
I Interosseous j Posterior interosSeous.
1 Muscular.
-prr . , j Anterior carpal.
Sand.
\
The anterior ulnar re-
current arises immediately
below the elbow-joint, passes
upwards and inwards be-
tween the Brachialis anticus
and Pronator radii teres,
supplies these muscles, and,
in front of the inner con-
dyle, anastomoses with the
anastomotica magna and in-
ferior profunda.
The posterior ulnar re-
current is much larger, and
arises somewhat lower than
the preceding. It passes
backwards and inwards, be-
neath the Flexor sublimis,
and ascends behind the inner
condyle of the humerus. In
the interval between this
eminence and the olecranon,
it lies beneath the Flexor
carpi ulnaris, ascending be-
tween the heads of that
muscle, beneath the ulnar
nerve ; it supplies the neigh-
boring muscles and joint,
and anastomoses with the
inferior profunda, anasto-
motica magna, and inter-
osseous recurrent arteries.
The interosseous artery is
a short trunk, about an
inch in length, and of con-
siderable size, which arises
immediately below the tu-
berosity of the radius, and,
passing backwards to the
upper border of the inter-
osseous membrane, divides
into two branches, the an-
terior and posterior inter-
osseous.
The anterior interosseous
passes down the forearm
on the anterior surface of
the interosseous membrane,
Posterior carpal.
Deep or communicating branch.
Digital.
Fig. 221. — Arteries of the Back of the Forearm and Hand.
rerrndintj Branrfl frvtm
Sup t rio rProfu n da,
Anasrta mot tea
Magna
Tturtrrici-
Viiiarlitcui-
Posterior Interoeseoit*
Poxtrrfor Carpal
( Ulnar)
Termination rf
ieriorlnterotvr out
Posterior Carpal
(Radial )
Dortalix fo/f/eU
Dorsalt 't Indiclt
416 ARTERIES.
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
descends in front of that muscle, to anastomose in front of the carpus with
branches from the anterior carpal and deep palmar arch. The continuation of
the artery passes behind the Pronator quadratus, and, piercing the interosseous
membrane, descends to the back of the wrist, where it anastomoses with the
posterior carpal branches a? the radial and ulnar arteries. The anterior inter-
osseous gives off a long, slender branch, which accompanies the median nerve,
and gives offsets to its substance. This, the median artery, is sometimes much
enlarged.
The posterior interosseous artery passes backwards through the interval be-
tween the oblique ligament and the upper border of the interosseous membrane,
and down the back part of the forearm, between the superficial and deep
layers of muscles, to both of which it distributes branches. Descending to the
back of the wrist, it anastomoses with the termination of the anterior inter-
osseous, and with the posterior carpal branches of the radial and ulnar arteries.
This artery gives off, near its origin, the posterior interosseous recurrent branch,
a large vessel, which ascends to the interval between the external condyle and
olecranon, beneath the Anconeus and Supinator brevis, anastomosing with a
branch from the superior profunda, and with the posterior ulnar recurrent
artery.
The muscular branches are distributed to the muscles along the ulnar side of
the forearm.
The carpal branches are intended for the supply of the wrist-joint.
The anterior carpal is a small vessel, which crosses the front of the carpus
beneath the tendons of the Flexor profundus, and inosculates with a corresponding
branch of the radial artery.
The posterior carpal arises immediately above the pisiform bone, winding
backwards beneath the tendon of the Flexor carpi ulnaris ; it gives off a branch
which passes across the dorsal surface of the carpus beneath the Extensor tendons,
anastomosing with a corresponding branch of the radial artery, and forming the
posterior carpal arch ; it is then continued along the metacarpal bone of the little
finger, forming its dorsal branch.
The deep or communicating branch arises at the commencement of the palmar
arch, passing deeply inwards 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 digital branches, 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 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 forwards with the digital
nerves to the clefts between the ringers, 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 plialanx, the two branches for each finger form an arch, from the convexity
of which branches pass to supply the matrix of the nail.
The Descending Aoeta.
The Descending Aorta is divided into two portions, thet horacic and abdominal,
in correspondence with the two great cavities of the trunk in which it is
situated.
THORACIC AORTA. 41T
The Thoracic Aorta.
The Thoracic Aorta commences at the lower border of the third dorsal
vertebra, on the left side, and terminates at the aortic opening in the Diaphragm,
in front of the last dorsal 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 column. The direction of this vessel
beino- influenced by the spine, upon which it rests, it is concave forwards in the
dorsal region, and, as the branches given off' from it are small, the diminution in
the size of the vessel is inconsiderable. It is contained in the back part of the
posterior mediastinum, being in relation, in front, from above downwards, with the
left pulmonary artery, the left bronchus, the pericardium, and the oesophagus ;
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 ; in front of this vessel, in the middle of its course ; whilst,
at its lower part, it is on the left side, on a plane anterior to it.
Plan of the Relations of the Thoracic Aorta.
In front.
Left pulmonary artery.
Left bronchus.
Pericardium.
(Esophagus.
Right side. / \ haft side.
(Esophagus (above). / Thoracic \ Pleura.
Vena azygos major. 1 Aorta. I Left lung.
Thoracic duct. \ J (Esophagus (below).
Behind.
Vertebral column.
Vena azygos minor.
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 be easily 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 backwards, along the left
side of the spine, producing absorption of the bodies of the vertebrae, causing extensive curva-
ture 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 back on each side of the
spine, beneath the integument, as a pulsating swelling, simulating abscess connected with dis-
eased 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 oeso-
phagus, causing pain and difficulty of swallowing, as in stricture of that tube, and ultimately even
open into it by ulceration, producing fatal hemorrhage. If the disease make its way to either 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 of the Thoracic Aorta.
Pericardiac. (Esophageal.
Bronchial. Posterior mediastinal.
Intercostal.
The pericardiac are a few small vessels, irregular in their origin, distributed to
the pericardium.
27
413 ARTERIES.
The bronchial arteries 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 they run, dividing and subdividing, upon
the bronchial tubes, supplying them, the cellular tissue of the lungs, the bronchial
glands, and the oesophagus.
The oesophageal arteries, usually four or five in number, arise from the front of
the aorta, and pass obliquely downwards to the oesophagus, forming a chain of
anastomoses along that tube, with the oesophageal branches of the inferior thyroid
arteries above, and with ascending branches from the phrenic and gastric arteries
below.
The posterior mediastinal arteries are numerous small vessels which supply the
glands and loose areolar tissue in the mediastinum.
The Intercostal arteries arise from the back part of the aorta. They are usually
ten in number on each side, the superior intercostal space (and occasionally the
second one) being supplied by the superior intercostal, a branch of the subclavian.
The right intercostals are longer than the left, on account of the position of the
aorta to the left side of the spine ; they pass outwards, across the bodies of the
vertebrae, to the intercostal spaces, being covered by the pleura, the oesophagus,
thoracic duct, sympathetic nerve, and the vena azygos major; the left passing
beneath the superior intercostal vein, the vena azygos minor, and sympathetic.
In the intercostal spaces, each artery divides into two branches, an anterior or
proper intercostal branch ; and a posterior or dorsal branch.
The anterior branch passes outwards, at first lying upon the External inter-
costal muscle, covered in front by the pleura, and a thin fascia. It then passes
between the two layers of Intercostal muscles, and, having ascended obliquely
to the lower border of the rib above, divides, near the angle of that bone, into
two branches ; of these, the larger runs in the groove, on the lower border of
the rib above; the smaller branch along the upper border of the rib below ; passing
forward, they supply the Intercostal muscles, and anastomose with the anterior
intercostal branches of the internal mammary, and with the thoracic branches of
the axillary artery. The first aortic intercostal anastomoses with the superior
intercostal, and the last three 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 intercostal spaces, where the nerve is at
first above the artery. The arteries are protected from pressure during the action
of the Intercostal muscles, by fibrous arches thrown across, and attached by each
extremity to the bone.
The posterior or dorsal branch of each intercostal artery passes backwards
to the inner side of the anterior costo-transverse ligament, and divides into a
spinal branch, which supplies the vertebrae, and the spinal cord and its membranes,
and a muscular branch, which is distributed to the muscles and integument of the
back.
The Abdominal Aoeta (fig. 222).
The Abdominal Aorta commences at the aortic opening of the Diaphragm, in
front of the body of the last dorsal vertebra, and, descending a little to the left
side of the vertebral column, terminates on the left side of the body of the fourth
lumbar vertebra, where it divides into the two common iliac arteries. As it lies
upon the bodies of the vertebrae, it is convex forwards, the greatest convexity
corresponding to the third lumbar vertebra, which is a little above and to the left
side of the umbilicus.
ABDOMINAL AORTA.
419
Relations. It is covered, in front, by the lesser omentum and stomach, behind
which are the branches of the coeliac 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 by the left lumbar veins, the receptaculum chyli, and thoracic
Fig. 222. — The Abdominal Aorta and its Branches.
duct. On the right side, with the inferior vena cava (the right crus of the
Diaphragm being interposed above), the vena azygos, thoracic duct, and right
semilunar ganglion. On the left side, with the sympathetic nerve, and left semi-
lunar ganglion.
420
ARTERIES.
Plan of the Eelations of the Abdominal Aorta.
In front.
Lesser omentum and stomach.
Branches of cceliac axis and solar plexus.
Splenic vein.
Pancreas.
Left renal vein.
Transverse duodenum.
Mesentery.
Aortic plexus.
Right side. Left side.
Right crus of Diaphragm. f >. Sympathetic nerve.
Inferior vena cava. / \ Left semilunar ganglion.
Vena azygos. r
Thoracic duct.
Right semilunar ganglion.
Behind.
Left lumbar veins.
Receptaculum chyli.
Thoracic duct.
Vertebral column.
Surgical Anatomy. Aneurisms of the abdominal aorta near the cceliac axis communicate in
nearly equal proportion with the anterior and posterior parts of this vessel.
"When an aneurismal sac is connected with the back part of the abdominal aorta, it usually
produces absorption of the bodies of the vertebra;, and forms a pulsating tumor, that presents
itself in the left hypochondriac or epigastric regions, accompanied by symptoms of disturbance
of 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 pressed on by the tumor; hence the pain in the loins, the testes, the hypo-
gastrium, and in the lower lfmb. usually of the left side. This form of aneurism usually bursts
into the peritoneal cavity, or behind the peritoneum, in the left hypochondriac 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 never rapidly fatal.
When aij aneurismal sac is connected with the front of the aorta, near the cceliac 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 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 Lyurst into the peritoneal cavity, or behind the peritoneum, between the layers
of the mesentery, or, more rarely, into the duodenum ; it rarely extends backwards so as to affect
the spine.
Branches of the Abdominal Aorta.
Phrenic.
I Gastric.
Cceliac axis. I Hepatic.
( Splenic.
Superior mesenteric.
Supra-renal.
Renal.
Spermatic.
Inferior mesenteric.
Lumbar.
Sacra media.
The branches of the abdominal aorta may be divided into two sets : 1. Those
supplying the viscera. 2. Those distributed to the walls of the abdomen.
Visceral Branches.
[ Gastric.
Cceliac axis. -! Hepatic.
( Splenic.
Superior mesenteric.
Inferior mesenteric.
Supra-renal.
Renal.
Spermatic.
Parietal Branches.
Phrenic.
Lumbar.
Sacra media.
CCELIAC AXIS.
421
Qeliac Axis *
To expose this artery, raise the liver, draw down the stomach, and then tear through the layers
of the lesser omentum.
The Coeliac Axis is a short thick trunk, about half an inch in length, arising
from the aorta, opposite the margin of the Diaphragm, and, passing nearly hori-
zontally forwards (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 right semilunar ganglion and cardiac end of the stomach. Below,
it rests upon the upper border of the pancreas.
Fig. 223.-
-The Coeliac Axis and its Branches, the Liver having been raised, and
the Lesser Omentum removed.
The 5a.stric Artery (Coronaria ventriculi), the smallest of the three brandies
of the coeliac axis, passes upwards and to the left side, 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, inoscu-
lating with branches of the splenic artery ; it then passes from left to right, along
the lesser curvature of the stomach to the pylorus, lying in its course between
the layers of the lesser omentum, and giving branches to both surfaces of the
organ ; at its termination it anastomoses with the pyloric branch of the hepatic.
The Hepatic Artery 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 coeliac
422
ARTERIES.
axis.
It passes upwards to the right side, 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 cor-
responding lobes of that organ, accompanying the ramifications of the vena portse
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
vein, the former lying to the right of the artery, and the vena portae behind.
Its branches are the
Pyloric.
Gastro-d uodenalis
Cystic.
Qastro-epiploica dextra.
Pancreatico-duodenalis.
Fip
224. — The Cceliac Axis and its Blanches, the Stomach having been raised, and
the Transverse Meso-colon removed.
Grtnt
K
The "pyloric branch arises from the hepatic, above the pylorus, descends to the
pyloric end of the stomach, and passes from right to left along its lesser curvature,
supplying it with branches, and inosculating with the gastric artery.
The gastro-duodenalis is a short but large branch, which descends behind
the duodenum, near the pylorus, and divides at the lower border of the stomach
into two branches, the gastro-epiploica dextra and the pancreatico-duodenalis.
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-ejriploica dextra runs from right to left along the greater curvature
SUPERIOR MESENTERIC- 423
of the stomach, between the layers of the great omentum, anastomosing about the
middle of the lower border of this organ with the gastro-epiploica sinistra from
the splenic artery. This vessel gives off numerous branches, some of which
ascend to supply both surfaces of the stomach, whilst others descend to supply
the great omentum.
The pancreatico-duodenalis descends along the contiguous margins of the duode-
num and pancreas. It supplies both these organs, and anastomoses with the
inferior pancreatico-duodenal branch of the superior mesenteric artery.
In ulceration of the duodenum, which frequently occurs in connection with
severe burns, this artery is often involved, and death may occur from hemorrhage
into the intestinal canal.
The cystic artery, usually a branch of the right hepatic, passes upwards and
forwards along the neck of the gall-bladder, and divides into two branches, one
of which ramifies on its free surface, the other between it and the substance of
the liver.
The Splenic Artery, in the adult, is the largest of the three branches of the
cceliac axis, and is remarkable for the extreme tortuosity of its course. It passes
horizontally to the left side behind 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 hilus of that organ to be distributed to
its structure, whilst others are distributed to the great end of the stomach.
The branches of this vessel are the
Pancreaticae parvae. Gastric (Yasa brevia).
Pancreatica magna. Gastro-epiploica sinistra.
The pancreaticse 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 pancreatic duct, and is called the pancreatica
magna. These vessels anastomose with the pancreatic branches of the pancreatico-
duodenal arteries.
The gastric (vasa brevia) consist 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 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.
Superior Mesenteric Artery.
In order to expose this vessel, raise the great omentum and transverse colon, draw down the
small intestines, and, if the peritoneum is divided where the transverse meso-colon and mesentery
join, this artery will be exposed just as it issues beneath the lower border of the pancreas.
The Superior Mesenteric Artery (fig. 225) supplies the whole length of the
small intestine, except the first part of the duodenum ; it also supplies the caecum,
ascending and transverse colon. It is a vessel of large size, arising from the fore
part of the aorta, about a quarter of an inch below the cceliac axis ; being covered,
at its origin, by the splenic vein and pancreas. It passes forwards, between the
pancreas and transverse portion of the duodenum, crosses in front of this portion
of the intestine, and descends between the layers of the mesentery to the right
iliac fossa, where it terminates considerably diminished in size. In its course it
forms an arch, the convexity being directed forwards and downwards to the left
side, the concavity backwards and upwards to the right. It is accompanied by
424
ARTERIES.
the superior mesenteric vein, and is surrounded by the superior mesenteric plexus
of nerves. Its branches are the
Inferior pancreatico-duodenal. Ileo-colic.
Vasa intestini tenuis. . Colica dextra.
Colica media.
The inferior pancreatico-duodenal is given off from the superior mesenteric
below the pancreas, and is distributed to the head of the pancreas, and the trans-
verse and descending portions of the duodenum ; anastomosing with the pancrea-
tico-duodenal artery.
Fig. 225.— The Superior Mesenteric Artery and its Branches.
The vasa intestini tenuis 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 and ileum. They run parallel with one another between the layers of
the mesentery ; each vessel dividing into two branches, which unite with a similar
branch on each side, forming a series of arches, the convexities of which are
directed towards 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 even a fourth or fifth series
of arches is constituted, diminishing in size the nearer they approach the intes-
tine. From the terminal arches numerous small straight vessels arise which
encircle the intestine, upon which they are minutely distributed, ramifying between
its coats.
INFERIOR MESENTERIC. 425
The ileo-colic artery 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
one inosculates with the lowest branches of the vasa intestini tenuis, from the
convexity of which branches proceed to supply the termination of the ileum, the
ccecum and appendix cceci, and the ileo-ccecal and ileo-colic valves. The superior
division inosculates with the colica dextra, and supplies the commencement of
the colon.
The colica dextra arises from about the middle of the concavity of the superior
mesenteric artery, and, passing beneath the peritoneum to the middle of the ascend-
ing 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 colica media arises from the upper part of the concavity of the superior
mesenteric, and, passing forwards 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 dis-
tributed to the transverse colon. The branches of this vessel lie between two
layers of peritoneum.
Inferior Mesenteric Artery.
In order to expose this vessel, draw the small intestines and mesentery over to the right side
of the abdomen, raise the transverse colon towards the thorax, and divide the peritoneum cover-
ing the left side of the aorta.
The Inferior Mesenteric Artery (fig. 226) supplies the descending and sig-
moid flexure of the colon, and 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 its division into the common iliacs. It passes downwards to the
left iliac fossa, and then descends, between the layers of the mesorectum, into the
pelvis, under the name of the superior hemorrhoidal artery. It lies at first in close
relation with the left side of the aorta, and then passes in front of the left common
iliac artery. Its branches are the
Colica sinistra. Sigmoid.
Superior hemorrhoidal.
The 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 anasto-
moses with the sigmoid artery. From the arches formed by these inosculations,
branches are distributed to the descending colon.
The sigmoid artery runs obliquely downwards across the Psoas muscle to the
sigmoid flexure of the colon, and divides into branches which supply that part of
the intestine ; anastomosing above, with the colica sinistra, and, below, with the
superior hemorrhoidal artery. This vessel is sometimes replaced by three or four
small branches.
The superior hemorrhoidal artery, the continuation of the inferior mesen-
teric, 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, where they divide into several small branches, which are distributed
between the mucous and muscular coats of that tube, to near its lower end ; anas-
tomosing with each other, with the middle hemorrhoidal arteries, branches of the
internal iliac, and with the inferior hemorrhoidal, branches of the internal pudic.
The student should especially remark, that the trunk of the vessel descends
426
ARTERIES.
along the hack part of the rectum as far as the middle of the sacrum before it
divides ; this is about a finger's length or four inches from the anus. In disease
Fig. 226. — The Inferior Mesenteric Artery and its Branches.
Midd.lt Jluviarrko.
Inferior KsmorrhoiJul
of this tube, the rectum should never be divided beyond this point in that direc-
tion, for fear of involving the artery.
SUPRA-RENAL ARTERIES.
The Supra-renal Arteries are two small vessels which arise, one on each side
of the aorta, opposite the superior mesenteric artery. They pass obliquely
upwards and outwards, to the under surface of the supra-renal capsules, to which
they are distributed, anastomosing with capsular branches from the phrenic and
renal arteries. In the adult these arteries are of small size ; in the foetus they are
as large as the renal arteries.
Renal Arteries.
The Renal Arteries are two large trunks, which arise from the sides of the
aorta, immediately below the superior mesenteric artery. Each is directed out-
wards, so as to form nearly a right angle with the aorta. The right one longer
than the left, on account of the position of the aorta, passes behind the inferior
vena cava. The left is somewhat higher than the right. Previously 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
PHRENIC AND LUMBAR. 427
ureter, the vein being usually in front, the ureter behind. Each vessel gives off
some small branches to the supra-renal capsules, the ureter, and to the surround-
ing cellular membrane and muscles.
Spermatic Arteries.
The Spermatic Arteries are distributed to the testes in the male, and to the
ovaria in the female. 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 outwards and downwards, behind the peritoneum, cross-
ing the ureter, and resting on the Psoas muscle, the right spermatic lying in
front of the inferior vena cava, the left behind the sigmoid flexure of the colon.
On reaching the margin of the pelvis, each vessel passes in front of the
corresponding external iliac artery, and takes a different course in the two sexes.
In the male, it is directed outwards, to the internal abdominal ring, and
accompanies the other constituents of the spermatic cord along the spermatic
canal to the testis, where it becomes tortuous, and divides into several branches,
two or three of which accompany the vas deferens, and supply the epididymis,
anastomosing with the artery of the vas deferens ; others pierce the back part of
the tunica albuginea, and supply the substance of the testis.
At an early period of foetal life, when the testes lie by the side of the spine,
below the kidneys, the spermatic arteries are short ; but as these organs descend
from the abdomen into the scrotum, they become gradually lengthened.
In the female, the spermatic arteries (ovarian) are shorter than in the male,
and do not pass out of the abdominal cavity. On arriving at the margins of the
pelvis, each artery passes inwards, between the two laminae of the broad ligament
of the uterus, to be distributed to the ovary. One or two small branches supply
the Fallopian tube ; another passes on to the side of the uterus, and anastomoses
with the uterine arteries. Other offsets are continued along the round ligament,
through the inguinal canal, to the integument of the labium and groin.
Phrenic Arteries.
The Phrenic Arteries are two small vessels, which present much variety in their
origin. They may arise separately from the front of the aorta, immediately below
the coeliac axis, or by a common trunk, which may spring either from the aorta, or
from the coeliac 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, 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 upwards and outwards
upon its under surface. The left phrenic passes behind the oesophagus, and runs
forwards on the left side of the oesophageal opening. The right phrenic passes
behind the liver and inferior vena cava, 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 forwards to the
front of the thorax, supplying the Diaphragm, and anastomosing with its fellow
of the opposite side, and with the musculo-phrenic, a branch of the internal
mammary. The external branch passes towards the side of the thorax, and in-
osculates with the intercostal arteries. The internal branch of the right phrenic
gives off a few vessels to the inferior vena cava; and the left one some branches
to the oesophagus. Each vessel also sends capsular branches to the supra-renal
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.
Lumbar Arteries.
The Lumbar Arteries are analogous to the intercostal. 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 outwards and backwards, around the sides of
428 ARTERIES.
the body of the corresponding lumbar vertebra, behind the sympathetic nerve
and the Psoas muscle ; those on the right side being covered by the inferior vena
cava, 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 divides
into a dorsal and an abdominal branch.
The dorsal branch gives off) immediately after its origin, a spinal branch,
which enters the spinal canal; it then continues its course backwards, between
the transverse processes, and is distributed to the muscles and integument of the
back, anastomosing with its fellow, and with the posterior branches of the inter-
costal arteries.
The spinal branch, besides supplying offsets which run along the nerves to the
dura mater and cauda equina, anastomosing with the other spinal arteries, divides
into two branches, one of which ascends on the posterior surface of the body of
the vertebra above, and the other descends on the posterior surface of the body of
the vertebra below, both vessels anastomosing with similar branches from neigh-
boring spinal arteries. The inosculations of these vessels on each side, throughout
the whole length of the spine, form a series of arterial arches behind the bodies
of the vertebras, which are connected with each other, and with a median longi-
tudinal vessel, extending along the middle of the posterior surface of the bodies
of the vertebrae, by transverse branches. From these vessels offsets are distributed
to the periosteum and bones.
The abdominal branches pass outwards, behind the Quadratus lumborum, the
lowest branch occasionally in front of that muscle, and, being continued between
the abdominal muscles, anastomose with branches of the epigastric and internal
mammary in front, the intercostals above, and those of the ilio-lumbar and circum-
flex iliac, below.
Middle Saceal Arteey.
The Middle Sacral Artery is a small vessel, about the size of a crow-quill,
which arises from the back part of the aorta, just at its bifurcation. 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 terminates by anastomosing
with the lateral sacral arteries. From it, 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.
Common Iliac Arteeies.
The abdominal aorta divides into the two common iliac arteries. The bifurcation
usually takes place on the left side of the body of the fourth lumbar vertebra.
This point corresponds to the left side of the umbilicus, and is on a level with a
line drawn from the highest point of one iliac crest to the other. The common
iliac arteries are about two inches in length; diverging from the termination of the
aorta, they pass downwards and outwards to the margin of the pelvis, and divide
opposite the intervertebral substance, between the last lumbar vertebra and the
sacrum, into two branches, the external and internal iliac arteries; the former
supplying the lower extremity ; the latter, the viscera and parietes of the pelvis.
The right common iliac is somewhat larger than the left, and passes more ob-
liquely across the body of the last lumbar vertebra. It is covered by the peri-
toneum, the ileum, the branches of the sympathetic nerve ; and crossed, at its
point of division, by the ureter. Behind, it is separated from the last lumbar
vertebra, by the two common iliac veins. On its outer side, it is in relation with
the inferior vena cava, and 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, the rectum and superior hemorrhoidal artery ; and crossed,
::t its point of bifurcation, by the ureter. The left common iliac vein lies partly
COMMON ILIAC.
429
on the inner side, and partly beneath the artery; on its outer side, it is in relation
with the Psoas magnus.
Branches. The common iliac arteries give off small branches to the peritoneum,
Psoae muscles, ureters, and to the surrounding cellular membrane, and occasionally
give origin to the ilio-lumbar, or renal arteries.
Peculiarities. Its 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 ; one case in nine being below, and one in
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 ; in one case in eight
being above, and in one in six below that point. 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 longest 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 one instance, the right common iliac was found wanting, the external and internal
iliacs arising directly from the aorta.
Fig. 227. — Arteries of the Felvis.
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, or on account
430 ARTERIES.
of secondary hemorrhage after amputation of the thigh high up. It has been seen, that the
origin of this vessel corresponds to the left side of the umbilicus on a level with a line drawn
from the highest point of one iliac crest to the opposite one, and its course to a line extending
from the left side of the umbilicus downwards towards the middle of Poupart's ligament The
line of incision required in the first steps of an operation for securing this vessel, would materially
depend upon the nature of the disease. If the surgeon select the iliac region, a curved incision,
about five inches in length, may be made, commencing on the left side of the umbilicus, carried
outwards towards the anterior superior iliac spine, and then along the upper border of Poupart's
ligament, as far as its middle. But if the aneurismal tumor should extend high up in the abdo-
men, along the external iliac, it is better to select the side of the abdomen, approaching the artery
from above, by making an incision from four to five inches in length, from about two inches above
and to the left of the umbilicus, carried outwards in a curved direction towards the lumbar region,
and terminating a little below the anterior superior iliac spine. The abdominal muscles (in either
case) 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 its accompanying vein. On the right
side, both common iliac veins, as well as the inferior vena cava, 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 the left instead of the right side, which would add much to the difficulty of an operation in
such a case. If the common iliac artery is so short that danger is to be apprehended from
secondary hemorrhage if 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. This operation has been performed in 17
cases, 9 of which were cured, and 8 died.
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 hemorrhoidal
branches of the internal iliac with the superior hemorrhoidal from the inferior mesenteric ; and
by 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 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 internal epigastric ; and of the gluteal with the posterior branches of the sacral arteries.
Internal Iliac Artery.
The Internal Iliac Artery supplies the walls and viscera of the pelvis, the gene-
rative organs, and inner side of the thigh. It is a short, thick vessel, smaller than
the external iliac, and about an inch and a-half in length, which arises at the point
of bifurcation of the common iliac ; and, passing downwards to the upper margin
of the great sacro-sciatic foramen, divides into two large trunks, an anterior and
posterior ; a partially obliterated cord, the hypogastric artery, extending from the
extremity of the vessel forwards to the bladder.
Relations. In front, with the ureter, which separates it from the peritoneum.
Behind, with the internal iliac vein, the lumbo-sacral nerve, 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 nerve.
Pyriformis muscle.
In the foetus, the internal iliac artery (hypogastric) is twice as large as the
external iliac, and appears the continuation of the common iliac. Passing forwards
INTERNAL ILIAC. 431
to the bladder, it ascends along the side of that viscus to its summit, to which
it gives branches ; it then passes upwards along the back part of the anterior wall
of the abdomen to the umbilicus, converging towards its fellow of the opposite
side. Having passed through the umbilical opening, the two arteries twine round
the umbilical vein, forming with it the umbilical cord ; and, ultimately, ramify in
the placenta. That portion of the vessel placed within the abdomen is called the
hypogastric artery ; and that external to that cavity, the umbilical artery.
At birth, when the placental circulation ceases, that portion of the hypogastric
artery which extends from the umbilicus to the summit of the bladder, contracts,
and ultimately dwindles to a solid fibrous cord; the portion of the same vessel
extending from the summit of the bladder to within an inch and a half of its origin,
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.
Peculiarities, as regards its 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 va/ies 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.
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. This 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 cau-
tiously divided, and the peritoneum pushed inwards from the iliac fossa towards the pelvis, the
finger may feel the pulsation of the external iliac at the bottom of the wound ; and, by tracing
this vessel upwards, 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 its length.
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, which occasionally happens, it would be preferable to apply a ligature to the common iliac,
or upon the external and internal iliacs at their origin. This operation has been performed in
seven cases, four of which recovered, and three died.
Collateral Circulation. In Mr. Owen's dissection of a case in which the internal iliac artery
hid 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 superior
profunda.1 In addition to the above, the circulation in the parts supplied by the internal iliac
would be 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 ; by the anastomoses of the circumflex, and
perforating branches of the femoral, with the sciatic ; of the gluteal with the posterior branches
of the sacral arteries ; of the ilio-lumbar with the last lumbar ; of the lateral sacral with the
middle sacral ; and by the anastomoses of the circumflex iliac with the ilio-lumbar and gluteal.
1 Medico-Chirurgical Transactions, vol. xvi.
432 ARTERIES.
Branches of the Internal Iliac.
From the Anterior Trunk. From the Posterior Trunk.
Superior vesical. Gluteal.
Middle vesical. Ilio-lumbar.
Inferior vesical. Lateral sacral.
Middle hemorrhoidal.
T r 7 ( Uterine.
In female. { T7- • 1
J [ Vaginal.
Obturator.
Internal pudic.
Sciatic.
The superior vesical 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 body and fundus of this 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.
The middle vesical, usually a branch of the superior, is distributed to the base
of the bladder, and under surface of the vesiculoe seminales.
The inferior vesical arises from the anterior division of the internal iliac, in
common with the middle hemorrhoidal, and is distributed to the base of the bladder,
the prostate gland, and vesiculae seminales. Those branches distributed to the
prostate communicate with the corresponding vessel of the opposite side.
The middle hemorrhoidal artery usually arises together with the preceding
vessel. It supplies the rectum, anastomosing with the other hemorrhoidal
arteries.
The uterine artery passes downwards 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 laj^ers of the broad ligament, it distributes branches to its
substance, anastomosing, near its termination, with a branch from the ovarian
artery. Branches from this vessel are also distributed to the bladder and ureter.
The vaginal artery 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.
The Obturator Artery usually arises from the anterior trunk of the internal
iliac, frequently from the posterior. It passes forwards below the brim of the
pelvis, to the canal in the upper border of the obturator foramen, and, escaping
from the pelvic cavity through this aperture, divides into an internal and an
external branch. In the pelvic cavity, this vessel lies upon the pelvic fascia,
beneath the peritoneum, and a little below the obturator nerve; and, whilst
passing through the obturator foramen, is contained in an oblique canal, formed
by the horizontal branch of the pubes, above; and the arched border of the
obturator membrane, below.
Branches. Within the pelvis, the obturator artery gives off an iliac branch to
the iliac fossa, which supplies the bone and the Iliacus muscle, and anastomoses
with the ilio-lumbar artery ; a vesical branch, which runs backwards to supply
the bladder; and & pubic branch, which is given off from the vessel just before it
leaves the pelvic cavity. This branch ascends upon the back of the pubes, com-
municating with offsets from the epigastric artery, and with the corresponding
vessel of the opposite side. This branch is placed on the inner side of the femoral
ring. External to the pelvis, the obturator artery divides into an external and
an internal branch, which are deeply situated beneath the Obturator externus
muscle ; skirting the circumference of the obturator foramen, they anastomose at
the lower part of this aperture with each other, and with branches of the internal
circumflex artery.
OBTURATOR— INTERNAL PUDIC. 433
The internal branch curves inwards along the inner margin of the obturator
foramen, distributing branches to the Obturator muscles, Pectineus, Adductors,
and Gracilis, and anastomoses with the external branch, and with the internal
circumflex artery.
The external branch curves round the outer margin of the foramen, to the space
between the Gemellus inferior and Quadratus femoris, where it anastomoses with
the sciatic artery. It supplies the Obturator muscles, anastomoses, as it passes
backwards, with the internal circumflex, and 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. In two out of every three cases the obturator arises from the internal iliae. In
one case in three and a half cases, 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. , . ,
When the obturator artery arises at the front of the pelvis from the epigastric, it descends
almost vertically downwards to the upper part of the obturator foramen. The artery in this
course usually descends in contact with the external iliac vein, and lies on the outer side of the
femoral ring (fig. 228) ; in such cases it would not be endangered in the operation for femoral
hernia. Occasionally, however, it curves inwards along the free margin of Gimbernat's ligament
(fig. 229), 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.
Variations in Origin and Course of Obturator Artery.
Fig. 228. Fig. 229.
The Internal Pudic is the smaller of the two terminal branches of the anterior
trunk of the internal iliac, and supplies the external organs of generation. It passes
downwards and outwards 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, to
the ramus of the ischium, being covered by the obturator fascia, and situated
about an inch and a half from the margin of the tuberosity ; it then ascends for-
wards and upwards along the ramus of the ischium, pierces the posterior layer of
the deep perineal fascia, and runs forwards along the inner margin of the ramus
of the pubes ; finally, it perforates the anterior layer of the deep perineal fascia,
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 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 great sacro-sciatic ligament ; and when it enters the pelvis,
it lies on the outer side of the ischio-rectal fossa, upon the surface of the Obtura-
tor internus muscle, contained in a fibrous canal formed by the obturator fascia
and the falciform process of the great sacro-sciatic ligament. It is accompanied
by the pudic veins, and the internal pudic nerve.
Peculiarities. The internal pudic is sometimes smaller than usual, or fails to give off one oi
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 pudic artery before its exit
28
434 ARTERIES.
from the great sacro-sciatic foramen, and passes forwards near the base of the bladder, on the
upper part of the prostate gland, to the perineum, where it gives off those 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 super-
ficial perineal, the artery of the bulb being derived, with the other two branches, from the acces-
sory vessel.
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 lateral operation
of lithotomy.
Branches. Within the pelvis, the internal pudic gives off several small branches,
which supply the muscles, sacral nerves, and viscera in this cavity. In the peri-
neum the following branches are given off.
Inferior or external hemorrhoidal. Artery of the bulb.
Superficial perineal. Artery of the corpus cavernosum.
Transverse perineal. Dorsal artery of the penis.
The external hemorrhoidal are two or three small arteries, which arise from
the internal pudic as it passes above the tuberosity of the ischium. Crossing the
ischio-rectal fossa, they are distributed to the muscles and integument of the anal
region.
The superficial perineal artery supplies the scrotum, and muscles and integu-
ment of the perineum. It arises from the internal pudic, in front of the preceding
branches, and piercing the lower border of the deep perineal fascia, runs across
the Transversus perinei, and through the triangular space between the Accelerator
urinas and Erector penis, both of which it supplies, and is finally distributed to
the skin of the scrotum and dartos. In its passage through the perineum it lies
beneath the superficial perineal fascia.
The transverse perineal is a small branch which arises either from the internal
pudic, or from the superficial perineal artery as it crosses the Transversus perinei
muscle. Piercing the lower border of the deep perineal fascia, it runs trans-
versely inwards along the cutaneous surface of the Transversus perinei muscle,
which it supplies, as well as the structures between the anus and bulb of the
urethra.
The artery of the bulb is a large but very short vessel, arising from the internal
pudic between the two layers of the deep perineal fascia, and passing nearly
transversely inwards, pierces the bulb of the urethra, in which it ramifies. It
gives off a small branch which* descends to supply Cowper's gland. This artery
is of considerable importance in a surgical point of view, as it is in danger of
being wounded in the lateral operation of lithotomy, an accident usually attended
with severe and alarming hemorrhage. This vessel is sometimes very small,
occasionally wanting, or even double. It sometimes arises from the internal pudic
earlier than usual, and crosses the perineum 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 for lithotomy. If, on the contrary, it should arise from an
accessory pudic, it lies more forward than usual, and is out of daDger in the
operation.
The artery of the corpus cavernosum, one of the terminal branches of the inter-
nal pudic, arises from that vessel while it is situated between the crus penis and
the ramus of the pubes ; piercing the crus penis obliquely, it runs forwards in the
corpus cavernosum by the side of the septum pectiniforme, to which its branches
are distributed.
The dorsal artery of the penis ascends between the crus and pubic symphysis,
and, piercing the suspensory ligament, runs forward on the dorsum of the penis to
the glans, where it divides into two 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 corresponding artery of the opposite side. It supplies
the integument and fibrous sheath of the corpus cavernosum.
SCIATIC.
435
Iuttrnai CircumjiMC
The internal pudic artery in the female is smaller than in the male. Its origin
and course are similar, and there is considerable analogy in the distribution of its
branches. The superficial artery supplies the labia pudendi ; the artery of the
bulb supplies the erectile tissue of the bulb of the vagina, whilst the two terminal
branches supply the clitoris ; the artery of the corpus cavernosum, the cavernous
body of the clitoris; and
the arteria dorsalis clitori- FiS- 230.-The Arteries of the Gluteal and Posterior Femoral
dis, the dorsum of that
organ.
The Sciatic Artery
(fig. 230), the larger of the
two terminal branches of
the anterior trunk of the
internal iliac, is distributed
to the muscles on the back
of the pelvis. It passes
down to the lower part of
the great sacro-sciatic fora-
men, behind the internal
pudic, resting on the sacral
plexus of nerves and Pyri-
formis muscle, and escapes
from the pelvis between
the Pyriformis and Coccy-
geus. It then descends in
the interval between the
trochanter major and tu-
berosity of the ischium,
accompanied by the sciatic
nerves, and covered by the
Gluteus maximus, and di-
vides into branches, which
supply the deep muscles at
the back of the hip.
Within the pelvis, it dis-
tributes branches to the
Pyriformis, Coccygeus, and
Levator ani muscles ; some
hemorrhoidal branches,
which supply the rectum,
and occasionally take the
place of the middle hemor-
rhoidal artery; and vesical
branches to the base and
neck of the bladder, vesi-
culae seminales, and pros-
tate gland. External to the
pelvis, it gives off the coccy-
geal, inferior gluteal, comes
nervi ischiadici, muscular,
and articular branches.
The coccygeal branch runs inwards, pierces the great sacro-sciatic ligament,
and supplies the Gluteus 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.
The comes nervi ischiadici is a long slender vessel, which accompanies the great
Super Untcrnal Art^ula
Terferntiny
Inferior Titrating
moruiia*
JJusruIam
External Jlrtlcular
436 ARTERIES.
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 muscles on the back part of the hip, anas-
tomosing with the gluteal, internal and external circumflex, and superior per-
forating arteries.
Some articular branches are distributed to the capsule of the hip-joint.
The Gluteal Artery is the largest branch of the internal iliac, and appears to
he 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 Obtu-
rator internus, and just previous to quitting that cavity a nutritious artery, which
enters the ilium.
The superficial branch passes beneath the Gluteus maximus, and divides into
numerous branches, some of which supply this 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 Gluteus minimus, and sub-
divides into two. Of these, the superior division, 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 crosses the
Gluteus minimus obliquely to the trochanter major, distributing branches to the
Glutei muscles, and inosculates with the external circumflex artery. Some
branches pierce the Gluteus minimus to supply the hip-joint.
The llio-lumbar Artery ascends beneath the Psoas muscle and external iliac
vessels, to the upper part of the iliac fossa, where it divides into a lumbar and an
iliac branch.
The lumbar branch supplies the Psoas and Quadratus lumborum muscles, anas-
tomosing with the last lumbar artery, and sends a small spinal branch through
the intervertebral foramen, between the last lumbar vertebra and the sacrum, into
the spinal canal, to supply the spinal cord and its membranes.
The iliac branch descends to supply the Iliacus internus, some offsets running
between the muscle and the bone, one of which 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 anastomosing in their course with the
gluteal, circumflex iliac, external circumflex, and epigastric arteries.
The Lateral Sacral Arteries are usually two in number on each side, superior
and inferior.
The superior, which is of large size, passes inwards, and, after anastomosing with
branches from the middle sacral, enters the first or second sacral foramen, is dis-
tributed 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.
The inferior branch 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 sacra media
and opposite lateral sacral arteries. In its course, it gives off branches, which
enter the anterior sacral foramina ; these, after supplying the bones and membranes
of the interior of the spinal canal, escape by the posterior sacral foramina, and are
distributed to the muscles and skin on the dorsal surface of the sacrum.
External Iliac Artery.
The External Iliac Artery is the chief vessel which supplies the lower limb. It
is larger in the adult than the internal iliac, and passes obliquely downwards and
outwards along the inner border of the Psoas muscle, from the bifurcation of the
common iliac to the femoral arch, where it enters the thigh, and becomes the
EXTERNAL ILIAC. 43t
femoral artery. The course of this vessel would be indicated by a line drawn
from the left side of the umbilicus to a point midway between the anterior supe-
rior spinous process of the ilium and the symphysis pubis.
Relations. In front, with the peritoneum, sub-peritoneal areolar tissue, the
intestines, 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
crossed in this situation by a branch of the genito-crural nerve and the circumflex
iliac vein ; the vas deferens curves down along its inner side. Behind, it is in rela-
tion with the external iliac vein, which, at the femoral arch, lies at its inner side ;
on the left side the vein is altogether internal to the artery. Externally, 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 Eelations of the External Artery.
In front.
Peritoneum, intestines, and iliac fascia.
Near f Spermatic vessels.
Poupart's j Genito-crural nerve.
Ligament, "j Circumflex iliac vein.
I Lymphatic vessels and glands.
Outer side. / \ Inner side.
Psoas magnus. ( External j External iliac vein and vas deferens
Iliac fascia. I Ihac- / at femoral arch.
Behind.
External iliac vein.
Surgical Anatomy. The application of a ligature to the external iliac maybe required in
cases of aneurism of the femoral artery, or in cases of secondary hemorrhage, after the latter
vessel has been tied for popliteal aneurism. This vessel may be secured in any part of its course,
excepting near its upper end, on account of the circulation through the internal iliac, and near
its lower end, on account of the origin of the epigastric and circumflex iliac vessels. One of
the chief points in the performance of the operation is to secure the vessel without injury to the
peritoneum. The patient having been placed in the recumbent position, an incision should be
made, commencing about an inch above and to the inner side of the anterior superior spinous
process of the ilium, and running downwards and outwards to the outer end of Poupart's liga-
ment, and parallel with its outer half, to a little above its middle. The abdominal muscles and
transversalis fascia having been cautiously divided, the peritoneum should be separated from the
iliac fossa and pushed towards 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 situated along 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 vein.
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 profunda artery; the internal pudic with the external pudic, and with the internal
circumflex. When the obturator arises from the epigastric, it is supplied with blood by branches,
either from the internal iliac, the lateral sacral, or from the internal pudic. The epigastric
receives its supply from the internal mammary and inferior intercostal arteries, and from the
internal iliac, hy the anastomoses of its branches with the obturator.
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 : —
Epigastric. Circumflex iliac.
The epigastric artery arises from the external iliac, a few lines above Poupart's
ligament. It at first descends to reach this ligament, and then ascends obliquely
upwards and inwards between the peritoneum and transversalis fascia, to the
438 ARTERIES.
margin of the sheath of the Rectus muscle. Having perforated the sheath near
its lower third, it ascends vertically upwards behind the Rectus, to which it is
distributed, dividing into numerous branches, which anastomose above the umbi-
licus with the terminal branches of the internal mammary and inferior intercostal
arteries. It is accompanied by two veins, which usually unite into a single trunk
before their termination in the external iliac vein. As this artery ascends from
Poupart's ligament to the Rectus, it lies behind the inguinal canal, to the inner
side of the internal abdominal ring, and immediately above the femoral ring, the
vas deferens in the male and the round ligament in the female crossing behind
the artery in descending into the pelvis.
Branches. The branches of this vessel are the cremasteric, which accompanies
the spermatic cord, and supplies the Cremaster muscle, anastomosing with the
spermatic artery ; a pubic branch, which runs across Poupart's ligament, and then
descends behind the pubes 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 circumflex iliac arteries ; others perforate the tendon of the External
oblique and supply the integument, anastomosing with branches of the external
epigastric.
Peculiarities. The origin of the 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 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 fur-
nished by the internal iliac, or the epigastric may be formed of two branches, one derived from
the external iliac, the other from the internal iliac.
The circumflex iliac artery arises from the outer side of the external iliac, nearly
opposite the epigastric artery. It ascends obliquely outwards behind Poupart's
ligament, and runs along the inner surface of the crest of the ilium to about its
middle, where it pierces the Transversalis and runs backwards between this
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. The
circumflex iliac artery is accompanied by two veins, which, uniting into a single
trunk, cross the external iliac artery just above Poupart's ligament, and enter
the external iliac vein.
Femoral Artery.
The Femoral Artery is the continuation of the external iliac. It commences
immediately beneath Poupart's ligament, midway between the anterior superior
spine of the ilium and the symphysis pubis, and, passing down the fore part 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. A line drawn from a point midway between the anterior supe-
rior spine of the ilium and the symphysis pubis to the inner side of the inner
condyle of the femur, will be nearly parallel with the course of the artery. This
vessel, at the upper part of the thigh, lies a little internal to the head of the
femur ; in the lower part of its course, on the inner side of the shaft of this bone ;
and between these two points, the vessel is separated from the bone by a consi-
derable interval.
In the upper third of the thigh the femoral artery is very superficial, being covered
by the integument, inguinal glands, and by the superficial and deep fasciae, and
is contained in a triangular space, called " Scarpa's triangle."
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 downwards,
and the sides of which are formed externally by the Sartorius, internally by the
FEMORAL.
439
Adductor longus, and the base, by Poupart's ligament. The floor of this space
is formed from without inwards by the Iliacus, Psoas, Pectineus, Adductor
longus, and a small part of the Adductor brevis 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 giving off in this Fig. 231. — Surgical Anatomy of the Femoral Artery,
situation its cutaneous and
profunda branches, the vein
receiving the deep femoral
and internal saphenous
veins. In this space, the
femoral artery rests on the
inner margin of the Psoas
muscle, which separates it
from the capsular ligament
of the hip-joint. The artery
in this situation is crossed
in front by the crural
branch of the genito-crural
nerve, and behind by the
branch to the Pectineus
from the anterior crural.
The femoral vein lies at
its inner side, between the
margins of the Pectineus
and Psoas muscles. The
anterior crural - nerve lies
about half an inch to the
outer side of the femoral
artery, deeply imbedded
between the Iliacus and
Psoas muscles; and on the
Iliacus muscle, internal to
the anterior superior spi-
nous process of the ilium,
is the external cutaneous
nerve. The femoral artery
and vein are inclosed in a
strong fibrous sheath, form-
ed by fibrous and cellular
tissue, and by a process of
fascia sent inwards from
the fascia lata ; the vessels
are separated, however,
from one another by thin
fibrous partitions.
In the middle third of the
thigh, the femoral artery is
more deeply seated, being
covered by the integument,
the superficial and deep
fascise, and the Sartorius, and is contained in an aponeurotic canal, formed by a
dense fibrous band, which extends transversely from the Vastus internus to the
tendons of the Adductor longus and Adductor magnus muscles. In this part of
its course it lies in a depression, bounded externally by the Vastus internus,
internally by the Adductor longus and Adductor magnus. The femoral vein lies
Zettg Saphenous Kern*
Ajiaetomcti en JUJucna
Super. External Art-infa
Jnfir. Eztrrnal Arlio
Anter. Tibial
—■AmultomoHrt*- XVxern
Sup*'.J*C*r*alArU**lut
.LUmnuil Artie f-
440 ARTERIES.
on the outer side of the artery, in close apposition with it, and, still more ex.
ternally, is the internal or long saphenous nerve.
Relations. From above downwards, the femoral artery rests upon the Psoas
muscle, which separates it from the margin of the pelvis and capsular ligament
of the hip; it is next separated from the Pectineus by the profunda vessels and
femoral vein ; it then lies upon the Adductor longus ; and lastly, upon the tendon
of the Adductor magnus, the femoral vein being interposed. To its inner side,
it is in relation, above, with the femoral vein, and, lower down, with the Ad-
ductor longus and Sartorius. To its outer side, the Vastus internus separates it
from the femur, in the lower part of its course.
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, as it descends, gets 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, but not within
the sheath of the vessels. Small cutaneous nerves cross the front of the
sheath.
Peculiarities. Double femoral reunited. Four cases are at present recorded, in which the
femoral artery divided into two trunks below the origin of the profunda, and became reunited
near the opening in 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 similar number of 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, escaping 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.
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-
foui'ths of a large number of cases, it arose between one and two inches below Poupart's liga-
ment ; 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.
Surgical Anatomy. Compression of the femoral artery, which is constantly requisite in am-
putations or other operations on the lower limb, is most effectually made immediately below
Poupart's ligament. In this situation, the artery is very superficial, and is merely separated
from the margin of the acetabulum and front of the head of the femur, by the Psoas muscle ; so
that the surgeon, by means of his thumb, or any other resisting body 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 outwards, so as to compress the vessel on the inner side of the shaft of the femur.
The application of a ligature to the femoral artery may be required in cases of wound or
aneurism of the arteries of the leg, of the popliteal or femoral ; and the vessel may be exposed
and tied in any part of its course. The great depth of this vessel in the lower part of its course,
its close connection 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.
Ligation of the femoral artery, within two inches of its origin, is usually considered very unsafe,
on account of the connection of large branches with it, the epigastric and circumflex iliac arising
just above its origin ; the profunda, from one to two inches below; occasionally, also, one of the
circumflex arteries arises from the vessel in the interspace between these. The profunda some-
times arises higher than the point above-mentioned, and rarely between two or three inches (in
one case four) below Pouparfs ligament. It would appear, then, that the most favorable situa-
tion for the application of a ligature to this vessel is between four and five inches from its point
of origin. In order to expose the artery in this situation, an incision, between two and three
inches long, should be made in the course of the vessel, the patient lying in the recumbent posi-
tion, with the limb slightly flexed and abducted. A large vein is frequently met with, passing
in the course of the artery to join the saphena ; this must be avoided, and the fascia lata having
BRANCHES OF THE FEMORAL. 441
been cautiously divided, and the Sartorius exposed, this muscle must be drawn outwards, in order
to fully expose the sheath of the vessels. The finger being introduced into the wound, and the
pulsation of the artery felt, the sheath should be divided over it to a sufficient extent to allow of
the introduction of the ligature, but no further; 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, a small nerve which crosses 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 the middle of the thigh, an incision should be made through the integu-
ment, between three and four inches in length, over the inner margin of the Sartorius, taking care
to avoid the internal saphenous vein, the situation of which may be previously known by com-
pressing it higher up in the thigh. The fascia lata having been divided, and the Sartorius muscle
exposed, it should be drawn outwards, 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 within outwards. The femoral vein in this
situation lies on the outer side of the artery, the long saphenous nerve on its anterior and outer
side.
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 aneu-
rismal tumor, or with the bleeding from the wound, and that one only tied which controls it. 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 had become reunited, as is mentioned above.
Collateral Circulation. The principal agents in carrying on the collateral circulation after
ligature of the 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 an artery 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 themselves
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."
Branches. The branches of the femoral artery are the
Superficial epigastric.
Superficial circumflex iliac.
Superficial external pudic.
Deep external pudic.
{External circumflex.
Internal circumflex.
Three perforating.
Muscular.
Anastomotica magna.
The superficial epigastric 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 inguinal
glands, the superficial fascia and integument, anastomosing with branches of the
deep epigastric and internal mammary arteries.
The superficial circumflex iliac, the smallest of the cutaneous branches, arises
close to the preceding, and, piercing the fascia lata, runs outwards, 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 inguinal glands-
anastomosing with the circumflex iliac, and with the gluteal and external circum
flex arteries.
1 Medico-Chirurgical Transactions, vol. ii. 1811.
442 ARTERIES.
The superficial external pudic (superior) arises from the inner side of the femoral
artery, close to the preceding vessels, and, after piercing the fascia lata at the
saphenous opening, passes inwards, across the spermatic cord, to be distributed to
the integument on the lower part of the abdomen, and of the penis and scrotum
in the male, and to the labia in the female, anastomosing with branches of the
internal pudic.
The deep external pudic (inferior), more deeply seated than the preceding, passes
inwards on the Pectineus muscle, covered by the fascia lata, which it pierces
opposite the ramus of the pubes, 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 Peofunda Femoris or Deep Femoral Artery 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 ligament. It at first lies on the outer
side of the superficial femoral, and then passes beneath it and the femoral vein to
the inner side of the femur, and terminates at the lower third of the thigh in a
small branch, which pierces the Adductor magnus, to be 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 Adductor
brevis and Adductor magnus muscles. In front, it is separated from the femoral
artery, above, by the femoral and profunda veins, and below by the Adductor
longus. On its outer side, the insertion of the Yastus internus separates it from
the femur.
Plan of the Relations of the Profunda Artery.
In front.
Femoral and profunda veins.
Adductor longus.
Outer side.
Vastus internus.
Behind.
Iliacus.
Adductor brevis.
Adductor magnus.
The External Circumflex Artery supplies the muscles on the front of the thigh.
It arises from the outer side of the profunda, passes horizontally outwards,
between the divisions of the anterior crural nerve, and beneath the Sartorius and
Rectus muscles, and divides into three sets of branches, ascending, transverse, and
descending.
The ascending tranches pass upwards, beneath the Tensor vaginas femoris
muscle, to the outer side of the hip, anastomosing with the terminal branches
of the gluteal and circumflex iliac arteries.
The descending branches, three or four in number, pass downwards, beneath
the Rectus, upon the Vasti muscles, to which they 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.
The transverse branches, the smallest and least numerous, pass outwards over
the Crureus, pierce the Vastus externus, and wind round the femur to its back
part, just below the great trochanter, anastomosing at the back of the thigh with
the internal circumflex, sciatic, and superior perforating arteries.
The Internal Circumflex Artery, smaller than the external, arises from the inner
and back part of the profunda, and winds round the inner side of the femur,
POPLITEAL SPACE. 443
between the Pectineus and Psoas muscles. On reaching the tendon of the Obtu-
rator externus, it divides into two branches ; one, ascending, is distributed to the
Adductor muscles, the Gracilis, and Obturator externus, anastomosing with the
obturator artery, the other descending, which passes beneath the Adductor brevis,
to supply it and the great Adductor ; the continuation of the vessel passing back-
wards, between the Quadratus femoris and upper border of the Adductor magnus,
anastomosing with the sciatic, external circumflex, and superior perforating arte-
ries. Opposite the hip-joint, this branch gives off an articular vessel, which
enters the joint beneath the transverse ligament ; and, after supplying the adipose
tissue, passes along the round ligament to the head of the bone.
The Perforating Arteries (fig. 230), usually three in number, are so called from
their perforating the tendons of the Adductor brevis and Adductor magnus muscles
to reach the back of the thigh. The first is given off above the A dductor brevis,
the second in front of that muscle, and the third immediately below it.
The first or superior perforating artery passes backwards between the Pectineus
and Adductor brevis (sometimes perforates the latter) ; it then pierces the Adduc-
tor magnus close to the linea aspera, and divides into branches which supply both
Adductors, the Biceps, and Gluteus maximus muscle ; anastomosing with the
sciatic, internal circumflex, and middle perforating arteries.
The second or middle perforating artery, larger than the first, pierces the tendons
of the Adductor brevis and Adductor magnus muscles, divides into ascending
and descending branches, which supply the Flexor muscles of the thigh, anasto-
mosing with the superior and inferior perforantes. The nutrient artery of the
femur is usually given off from this branch.
The third or inferior perforating artery 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 with the perforating arteries, above, and with
the terminal branches of the profunda, below.
Muscular Branches 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 arises from the femoral artery just before it passes
through the tendinous opening in the Adductor magnus muscle, and divides into
a superficial and deep branch.
The superficial branch accompanies the long saphenous nerve, beneath the
Sartorius, and, piercing the fascia lata, is distributed to the integument.
The deep branch 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 and recurrent branch of the
anterior tibial. A branch from this vessel crosses outwards above the articular
surface of the femur, forming an anastomotic arch with the superior external arti-
cular artery, and supplies branches to the knee-joint.
The Popliteal Space.
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 transverse incision passing 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 tig. 189.
On removing the integument, the superficial fascia is exposed, and ramifying in
it along the middle line are found some filaments of the small sciatic nerve, and,
towards the inner part, some offsets from the internal cutaneous nerve.
The superficial fascia having been removed, the fascia lata is brought into view.
In this region it is strong and dense, being strengthened by transverse fibres, and
firmly attached to the tendons on the inner and outer sides of the space. It is
perforated below by the external saphenous vein. This fascia having been reflected
back in the same direction as the integument, the small sciatic nerve and external
444 ARTERIES.
saphenous vein are seen immediately beneath it, in the middle line. If the loose
adipose tissue is now removed, the boundaries and contents of the space may be
examined.
Boundaries. The popliteal space, or the ham, occupies the lower third of the
thigh and the upper fifth of the leg ; extending from the aperture in the Adductor
magnus to the lower border of the Popliteus muscle. It is a lozenge-shaped
space, being widest at the back part of the knee-joint, and deepest above the arti-
cular end of the femur. It is bounded, externally, above the joint, by the Biceps,
and below the articulation, by the Plantaris and external head of the Gastroc-
nemius ; internally, above the joint, by the Semi-membranosus, Semi-ten-
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 Gastrocnemius. 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 their branches, the small sciatic nerve, the articular branch from the
obturator nerve, a few small lymphatic glands, and a considerable quantity of
loose adipose tissue.
Position of contained parts. The internal popliteal nerve descends in the middle
line of the space, lying superficial, and a little external to the vein and artery.
The external popliteal nerve descends on the outer side 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 and a little external to the artery,
to which it is closely united by dense areolar tissue ; sometimes the vein is placed
on the inner instead of the outer side of the artery ; or the vein may be double,
the artery then lying between them, the two veins being usually connected by short
transverse branches. More deeply, and 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 surrounaing 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. In health, these glands are small ; but when enlarged and indu-
rated from inflammation, the pulsation communicated to them from the popliteal
artery makes them resemble so closely an aneurismal tumor, that it requires a
very careful examination to discriminate between them.
Popliteal Artery.
The Popliteal Artery commences at the termination of the femoral, at the
opening in the Adductor magnus, and, passing obliquely downwards and outwards
behind the knee-joint to the lower border of the Popliteus muscle, divides into
the anterior and posterior tibial arteries. Through this extent the artery lies in
the popliteal space.
In its course downwards from the aperture in the Adductor magnus to the lower
border of the Popliteus muscle, the Popliteal artery (fig. 232) rests first on the
inner, and then on the posterior surface of the femur ; in the middle of its course,
on the posterior ligament of the knee-joint ; and below, on the fascia covering
the Popliteus muscle. Superficially, it is covered, above, by the Semi-membra-
nosus ; 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.
POPLITEAL. 445
The popliteal vein,, which is intimately attached to the artery, lies superficial and
external to it, until near its termination, when it crosses it and lies to its inner
side. The popliteal nerve is still more superficial and external, crossing, however,'
the artery below the joint, and lying on its inner side. Laterally, it is bounded
by the muscles which form the boundaries of the popliteal space.
/' culiarttiea in point of division. Occasionally the popliteal artery divides prematurely into
its terminal branches ; this division occurs most frequently opposite the knee-joint.
Unusual branches. This artery sometimes divides into the anterior tibia2 and peroneal, the
posterior tibial being wanting, or very small. In a single case, this artery divided into three
branches, the anterior and posterior tibial, and peroneal.
Surgical Anatomy. Ligation 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 space
the operation is attended with considerable difficulty, from the great depth of the artery, and
from the extreme degree of tension of its lateral boundaries.
In order to expose the vessel in the upper part of its course, the patient should be placed in
the prone position, with the limb extended. An incision about three inches in length should then
be made through the integument, along the posterior. margin of the Semi-membranosus, and, the
fascia lata having been divided, this muscle must be drawn inwards, when the pulsation of the
Vessel will be detected with the finger; the nerve lies on the outer or fibular side of the artery,
the vein, superficial and also to its outer side ; having cautiously separated it from the artery,
the aneurism needle should be passed around the latter vessel from without inwards.
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 same position as in the preceding
operation. 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 Gastrocnemius.
Some muscular branches of the popliteal should, if possible, be avoided, or, if divided, tied immedi-
ately. The leg being now flexed, in order the more effectually to separate the two heads of the
Gastrocnemius, the nerve should be drawn inwards and the vein outwards. &ad the aneurism
needle passed between the artery and vein from without inwards.
The branches of the popliteal artery are the
Muscular \ T JP . ' 0 ,
( Interior or Sural.
Cutaneous.
Superior external articular.
Superior internal articular.
Azygos articular.
Inferior external articular.
Inferior internal articular.
The superior muscular branches, two or three in number, arise from the upper
part of the popliteal artery, and are distributed to the Vastus externus and Flexor
muscles of the thigh; anastomosing with the inferior perforating, and terminal
branches of the profunda.
The inferior muscular or sural are two large branches, which are distributed
to the two heads of the Gastrocnemius and Plantaris muscles. They arise from
the popliteal artery opposite the knee-joint.
Cutaneous branches descend on each side and in the middle of the limb, between
the Gastrocnemius and integument ; they arise separately from the popliteal
artery, or from some of its branches, and supply the integument of the calf.
The superior articular arteries, two in number, arise one on either side of the
popliteal, and wind round the femur immediately above its condyles to the front
of the knee-joint.
The internal branch passes beneath the tendon of the Adductor magnus, and
divides into two, one of which supplies the Vastus internus, inosculating with the
aua.stomotica magna and inferior internal articular ; the other ramifies close to the
446
ARTERIES.
232.— The Popliteal, Posterior Tibial,
and Peroneal Arteries.
*'•■
surface of the femur, supplying it and the knee-joint, and anastomosing with the
superior external articular artery.
The external branch passes above the outer condyle, beneath the tendon of the
Biceps, and divides into a superficial and
Fig. 232.— The Popliteal, Posterior Tibial, deep branch : the superficial branch sup-
plies the Vastus externus, and anastomoses
with the descending branch of the exter-
nal circumflex artery ; 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 artery.
The azygos articular is a small branch,
arising from the popliteal 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 articulation.
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 one 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.
The external one passes outwards above
the head of the fibula, to the front of the
knee-joint, lying in its course beneath the
outer head of the Gastrocnemius, the
external lateral ligament, and the tendon
of the Biceps muscle, and divides into
tfM J^Lhicus I branches, which anastomose with the
\{:'J artery of the opposite side, the superior
articular, and the recurrent branch of the
anterior tibial.
Anterior Tibial Arteey.
The Anterior Tibial Artery commences
-Anterior Peroneal at the bifurcation of the popliteal, at the
lower border of the Popliteus muscle,
passes forwards between the two heads
of the Tibialis posticus, and through the
aperture left between the bones at the
upper part of the interosseous membrane,
to the deep part of the front of the leg;
it then descends on the anterior surface
of the interosseous ligament, and of the
tibia, to the front of the ankle-joint, where
it lies more superficially, and becomes the
dorsalis pedis. A line drawn from the
inner side of the head of the fibula to
midway between the two malleoli, will
be parallel with the course of the artery.
ANTERIOR TIBIAL. 447
Relations. In the upper tworthirds of its extent, it rests upon the interosseous
ligament, 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 pollicis. In the lower third, it is crossed by the tendon of
the Extensor proprius pollicis, 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, annular ligament, and fascia.
The anterior -tibial artery is accompanied by two veins (venae comites), which
lie one on either side of the artery ; the anterior tibial nerve lies at first to its outer
side, and about the middle of the leg is placed superficial to it ; at the lower part
of the artery, the nerve is on the outer side.
Plan of the Kelations of the Anterior Tibial Artery.
In front.
Integument, superficial and deep fasciae.
Tibialis anticus.
Extensor longus digitorum.
Extensor proprius pollicis.
Anterior tibial nerve.
Inner side. • f \ Outer side.
Tibialis anticus. / . \ Anterior tibial nerve.
Extensor proprius pollicis. ( Vibiai°r ) Extensor longus digitorum.
Extensor proprius pollicis.
Behind.
Interosseous membrane.
Tibia.
Anterior ligament of ankle-joint.
Peculiarities in Size. This vessel may be diminished in size, or it may be deficient to a greater
or less extent, or it 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. This artery occasionally deviates in its course towards the fibular side of the leg,
regaining its usual position beneath the annular ligament at the front of the ankle. In two
instances, this vessel has approached the surface in the middle of the leg, from this point onwards
being covered merely by the integument and fascia.
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 attended with great difficulty, on account of the depth
of the vessel from the surface. An incision, about four inches in length, should be made through
the integument, midway between the spine of the tibia and the outer margin of the fibula, the
fascia and intermuscular septum between the Tibialis anticus and Extensor communis digitorum
being divided to the same extent. The foot must be flexed to relax these muscles, which
must be separated from each other by the finger. The artery is then exposed, deeply seated,
lying upon the interosseous membrane, the nerve lying externally, and one of the venae comites
on either side ; these must be separated from the artery before the aneurism needle is passed
round it. .
To tie this 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 pollicis 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 superficial to it, and one of the venae comites on either side.
In order to secure this vessel over the instep, an incision should be made on the fibular side
of the tendon of the Extensor proprius pollicis, between it and the innermost tendon of the long
Extensor ; the deep fascia having been divided, the artery will be exposed, the nerve lying either
superficial to it, or to its outer side.
448*
ARTERIES.
The branches of the anterior tibial
Fit
233. — Snrgical Anatomy of the Anterior
Tibial and Dorsalis Pedis Arteries.
CnurauicaZl
xrtery are the
Recurrent tibial.
Muscular.
Internal malleolar.
External malleolar.
The recurrent branch 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.
The 'muscular branches are numerous ;
they are distributed to the muscles which
lie on either side of the vessel, some
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 arises about two inches
above the articulation, passes beneath the
tendon of the Tibialis anticus to the inner
ankle, upon which it ramifies, anastomos-
ing with branches of the posterior tibial
and internal plantar arteries.
The external passes beneath the ten-
dons of the Extensor longus digitorum
and Extensor proprius pollicis, and sup-
plies the outer ankle, anastomosing with
the anterior peroneal artery, and with
ascending branches from the tarsea branch
of the dorsalis pedis.
Doesalis Pedis Artery.
The Dorsalis Pedis, the continuation of
the anterior tibial, passes forwards from
the bend of the ankle along the tibial side
of the foot to the back part of the first
interosseous space, where it divides into
two branches, the dorsalis hallucis and
communicating.
Relations. This vessel, in its course for-
wards, rests upon the astragalus, scaphoid,
and internal cuneiform bones, and the
ligaments connecting them, being covered
by the integument and fascia, 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 pollicis ; on its fibular
side, the innermost tendon of the Extensor
longus digitorum. It is accompanied by
two veins, and by the anterior tibial nerve,
which lies on its outer side.
DORSALIS PEDIS. 449
Plan of the Kelations of the Dorsalis Pedis Artery.
In front.
Integument and fascia.
Innermost tendon of Extensor brevis digitorum.
Tibial side. / \ Fibular side.
Extensor proprius pollicis. ( 1klLIMa31a \ Extensor longus digitorum
Anterior tibial nerve.
Behind.
Astragalus.
Scaphoid.
Internal cuneiform.
Their ligaments.
Peculiarities in Size. The dorsal artery of the foot may be larger than usual, to compensate
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.
Position. This artery frequently curves outwards, lying external to the line between the
middle of the ankle and the back part of the first interosseous space.
Surgical Anatomy. This artery may be tied, by making an incision through the integument,
between two and three inches in length, on the fibular side of the tendon of the Extensor pro-
prius pollicis, in the interval between it and the inner border of the short Extensor muscle. The
incision should not extend further forwards than the back part of the first interosseous space, as
the artery divides in this situation. The deep fascia being divided to the same extent, the artery
will be exposed, the nerve lying upon its outer side.
Branches. The branches of the dorsalis pedis are the
Tarsea. . Interossese.
Metatarsea. Dorsalis hallucis.
Communicating.
The tarsea artery arises from the dorsalis pedis, as that vessel crosses the sca-
phoid bone ; it passes in an arched direction outwards, 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 metatarsea,
external malleolar, peroneal, and external plantar arteries.
The metatarsea arises a little anterior to the preceding ; it passes outwards 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 tarsea and external plantar arteries. This
vessel gives off three branches, the interossese, which pass forwards upon the
three outer Dorsal interossei muscles, and, in the clefts between the toes, divide
into two dorsal collateral branches for the adjoining toes. At the back part of
each interosseous space these vessels receive the posterior perforating branches
from the plantar arch ; and at the fore part of each interosseous space, they are
joined by the anterior perforating branches from the digital arteries. The outer-
most interosseous artery gives off a branch which supplies the outer side of the
little toe.
The dorsalis halhicis runs forwards along the outer border of the first meta-
tarsal bone, and, at the cleft between the first and second toes, divides into two
branches, one of which passes inwards, beneath the tendon of the Flexor longus
pollicis, and is distributed to the inner border of the great toe ; the other branch
bifurcating to supply the adjoining sides of the great and second toes.
The communicating artery dips down into the sole of the foot, between the two
heads of the first Dorsal interosseous muscle, and inosculates with the termination
29
450 ARTERIES.
of the external plantar artery, to complete the plantar arch. It here gives off
two digital branches ; one runs along the inner side of the great toe, on its plantar
surface, the other passes forwards along the first metatarsal space, and bifurcates
for the supply of the adjacent sides of the great and second toes.
Posterior Tibial Artery.
The Posterior Tibial is an artery of large size, which extends obliquely down-
wards 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 pollicis, 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, and, below, upon the tibia and back part of the ankle-joint. It is
covered by the intermuscular fascia, which separates it above from the Gastroc-
nemius and Soleus muscles. In the lower third, where it is more superficial, it is
covered only by the integument 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 digiterum.
Tibia.
Ankle-joint.
Inner side. f \ Outer side.
Posterior tibial nerve, / Posterior \ Posterior tibial nerve,
upper third. I Tibial. I lower two-thirds.
Behind.
Gastrocnemius.
Soleus.
Deep fascia and integument.
Behind the Inner Ankle, the tendons and bloodvessels are arranged in the
following order, from within outwards : First, the tendons of the Tibialis posticus
and Flexor longus digitorum, lying in the same groove, behind the inner mal-
leolus, 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 pollicis.
Peculiarities in Size. The posterior tibial is not unfrequently smaller than usual, or absent,
its place being compensated for by a large peroneal artery, which passes inwards at the lower end
of the tibia, and either joins the small tibial artery, or continues alone to the sole of the foot.
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 injury of the artery
PERONEAL. 451
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 should be made through
the integument, about two inches and a half in length, midway between the heel and inner ankle,
but a little nearer the latter. The subcutaneous cellular membrane 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 towards the ankle,
in order to avoid the posterior tibial nerve, care being at the same time taken not to include the
venae 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 two layers of fascia must be divided upon a director, when the
artery is exposed along the inner margin of the Flexor longus digitorum, with one of its venae
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, and from its being covered in by the Gastrocne-
mius a"d Soleus muscles. The patient being placed in the recumbent position, 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, along 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 inwards, so as to
avoid wounding the posterior tibial nerve.
The branches of the posterior tibial artery are the
Peroneal. Nutritious.
Muscular. Communicating.
Internal calcanean.
The Peroneal Artery 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 outwards to the fibula, and then
descends along the inner border of this bone 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, supplying the neighboring
muscles and back of the ankle, and anastomosing with the external malleolar,
tarsal, and external plantar arteries.
Relations. This vessel rests at first upon the Tibialis posticus, and, in the
greater part of its course, in the fibres of the Flexor longus pollicis, in a groove
between the interosseous ligament and the bone. It is covered, in the upper part
of its course, by the Soleus and deep fascia : below, by the Flexor longus pollicis.
Plan of the Relations of the Peroneal Artery.
In front.
Tibialis posticus.
Flexor longus pollicis.
Outer side.
Fibula.
Behind.
Soleus.
Deep fascia.
Flexor longus pollicis.
452 ARTERIES.
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, either reinforcing the posterior tibial by
its junction with it, or by altogether taking 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.
The peroneal artery, in its course, gives off branches to the Soleus, Tibialis
posticus, Flexor longus pollicis, and Peronei muscles, and a nutrient branch to
the fibula. The anterior peroneal pierces the interosseous membrane, about two
inches above the outer malleolus, to reach the fore part 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 nutritious artery of the tibia arises from the posterior tibial near its origin,
and, after supplying a few muscular branches, enters the nutritious canal of that
bone, which it traverses obliquely from above downwards. This is the largest
nutrient artery of bone in the body.
The muscular branches are distributed to the Soleus and deep muscles along
the back of the leg.
The communicating branch to the peroneal runs transversely across the back
of the tibia, about two inches above its lower end, passing beneath the Flexor
longus pollicis.
The internal calcanean consists of several large branches, which arise from
the posterior tibial just before its division ; they are distributed 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
arteries.
Plantae Aeteeies.
The Internal Plantar Artery, much smaller than the external, passes forwards
along the inner side of the foot. It is at first situated above the Abductor pollicis,
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
branches.
The External Plantar Artery, much larger than the internal, passes obliquely
outwards and forwards to the base of the fifth metatarsal bone. It then turns
obliquely inwards to the interval between the bases of the first and second meta-
tarsal bones, where it inosculates with the communicating branch from the dorsalis
pedis artery, thus completing the plantar arch. As this artery passes outwards it
is at first placed between the os calcis and Abductor pollicis, and then between
the Flexor brevis digitorum and Flexor accessorius ; and as it passes forwards
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 remaining portion of the vessel is deeply situated : it extends from the base
of the metatarsal bone of the little toe to the back part of the first interosseous
space, and forms the plantar arch ; it is convex forwards, lies upon the Interossei
muscles, opposite the tarsal ends of the metatarsal bones, and is covered by the
Adductor pollicis, the Flexor tendons of the toes, and the Lumbricales.
Branches. The plantar arch, besides distributing numerous branches to the
muscles, integument, and fascia3 in the sole, gives off the following branches : —
Posterior perforating. Digital — Anterior perforating.
The Posterior Perforating are three small branches, which ascend through the
back part of the three outer interosseous spaces, between the heads of the Dorsal
PLANTAR— PULMONARY.
453
interossei muscles, and anastomose with the interosseous branches from the meta-
tarsal artery.
The Digital Branches are four in number, and supply the three outer toes and
half the second toe. The first passes outwards 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. The second, third, and fourth run for-
wards along the metatarsal spaces, and, on arriving at the clefts between the toes,
divide into collateral branches, which supply the adjacent sides of the three outer
toes and the outer side of the second. At the bifurcation of the toes, each digital
artery sends upwards, through the fore part of the corresponding metatarsal space,
a small branch, which inosculates with the interosseous branches of the metatarsal
artery. These are the anterior perforating branches.
Fig. 234.— The Plantar Arteries.
Superficial View.
Fig. 235.— The Plantar Arteries.
Deep View.
Cemmanicattnj
Branch of
QOASAli* PUIS
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, being supplied by the dorsal artery of
the foot.
Pulmonary Artery.
The Pulmonary Artery conveys the venous blood from the right side of the heart
to the lungs. It is a short wide vessel, about two inches in length, arising from
the left side of the base of the right ventricle, in front of the ascending aorta.
It ascends obliquely upwards, backwards, and to the left side, as far as the under
surface of the arch of the aorta, where it divides into two branches of nearly
equal size, the right and left pulmonary arteries.
Relations. The greater part of this vessel is contained, together with the
ascending part of the arch of the aorta, in the pericardium, being inclosed with it
in a tube of serous membrane, continued upwards from the base of the heart,
454 ARTERIES.
and has attached to it, above, the fibrous layer of this membrane. Behind, it
rests at first upon the ascending aorta, and higher up in front of the left auricle.
On either side of its origin are the appendix of the corresponding auricle, and a
coronary artery ; and higher up it passes to the left side of the ascending aorta.
A little to the left of its point of bifurcation, it is connected to the under surface
of the arch of the aorta by a short fibrous cord, the remains of a vessel peculiar
to foetal life, the ductus arteriosus.
The right pulmonary artery, longer and larger than the left, runs horizontally
outwards, behind the ascending aorta and superior vena cava, to the root of the
right lung, where it divides into two branches, of which the lower, the larger,
supplies the lower lobe ; the upper giving a branch to the middle lobe.
The left pulmonary artery, shorter and somewhat smaller than the right, passes
horizontally in front of the descending aorta and left bronchus to the root of the
left lung, where it divides into two branches for the two lobes.
The author has to acknowledge valuable aid derived from the following works : Harrison's " Sur-
gical Anatomy of the Arteries of the Human Body," Dublin, 1824. — Richard Quain's ''Ana-
tomy of the Arteries of the Human Body," London, 1844. — Sibson's " Medical Anatomy," and
the other works on General and Microscopic Anatomy before referred to.
Of 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.
The Pulmonary Veins, unlike other vessels of this kind, contain arterial blood,
which they return from the lungs to the left auricle of the heart.
The Systemic Veins return the venous blood from the body generally to the
right auricle of the heart.
The Portal Vein, an appendage to the systemic venous system, 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 vena portae. From
this organ, the same blood is conveyed to the inferior vena cava by means of the
hepatic veins.
The veins, like the arteries, are found in nearly every tissue of the body ; they
commence by minute plexuses, which communicate with the capillaries, the
branches from which, uniting together, constitute trunks, which increase in size
as they pass towards the heart, from the termination of larger branches in them.
The veins are larger and altogether more numerous than the arteries ; hence, the
entire capacity of the venous system is much greater than the arterial, the pul-
monary veins excepted, which do not 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 not perfectly cylindrical, like the arteries, their walls being
collapsed when empty, and the uniformity of their surface being interrupted at
intervals by slight contractions, which indicate the existence of valves in their
interior. They usually retain, however, the same calibre as long as they receive
no neighboring branches.
The veins communicate very freely with one another, especially in certain
regions of the body ; and this communication exists between the larger trunks
as well as between the smaller branches. Thus in the cavity of the cranium, and
between the veins of the neck, where obstruction of the cerebral venous system
would be attended with imminent danger, we find that the sinuses and larger
veins have large and very frequent anastomoses. The same free communication
exists between the veins throughout the whole extent of the spinal canal, and
between the veins composing the various venous plexuses in the abdomen and
pelvis, as the spermatic, uterine, vesical, prostatic, etc.
The veins are subdivided into three sets ; superficial, deep, and sinuses.
The Superficial or Cutaneous Veins are found between the layers of superficial
fascia, immediately beneath the integument; they return the blood from these
structures, and communicate with the deep veins by perforating the deep
fascia.
The Deep Vein's accompany the arteries, and are usually inclosed in the same
sheath with those vessels. In the smaller arteries, as the radial, ulnar, brachial,
tibial, peroneal, they exist generally in pairs, one lying on each side of the vessel,
and are called vense comites. The larger arteries, as the axillary, subclavian,
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 exist, for example, in the interior of the skull,
and are formed by a subdivision of the layers of the dura mater ; their outer coat
455
456 VEINS.
consisting of fibrous tissue, their inner of a serous membrane continuous with the
serous membrane of the veins.
Veins have thinner walls than the arteries, which is due to the small amount
of elastic and muscular tissues which they contain. The superficial veins usually
have thicker coats than the deep veins, and the veins of the lower limbs are
thicker than those of the upper.
Veins are composed of three coats ; internal, middle, and external.
The internal coat is similar in structure to that of the arteries. In the smallest
veins, it consists of epithelium and nucleated connective tissue, arranged so as to
form an outer and an inner layer ; the latter, which is the thinnest, representing
the middle coat. As these vessels approach the capillaries, the epithelium and
outer layer of connective tissue become gradually lost. On the contrary, in those
of rather larger size, there is superadded a layer of muscular fibre-cells, a circu-
lar fibrous coat, with areolar elastic tissue beneath the epithelium, and in the
muscular and external coats. In medium-sized veins, the internal coat consists of
epithelium supported on one or more striped nucleated lamellae, external to which
is a layer of elastic fibrous tissue. In the veins of the gravid uterus, and in the
long saphenous and popliteal veins, muscular tissue is one of the component parts
of the inner coat. In the largest veins, as the inferior vena cava, the trunks of
the hepatic, and in the innominate veins, the internal coat has a structure similar
to that already mentioned ; but is somewhat thicker, owing to the increase in the
number of the striped lamellae, and the greater thickness of the elastic fibrous coat.
The middle coat is thin, and differs in structure from the middle coat of arteries
in containing a smaller amount of elastic and muscular tissues, and more con-
nective tissue. In the smallest veins, as already mentioned, it consists merely of
a thin layer of nucleated connective tissue, the fibres of which run in a longitu-
dinal direction ; to which is added, in those of rather larger size, a layer of mus-
cular tissue, the cells of which are disposed transversely. In medium-sized veins,
such as the cutaneous and deep veins of the limbs, as far as the brachial and pop-
liteal, and the visceral veins, the middle coat is of a reddish-yellow color, remark-
able for its great thickness, being more developed than the same coat in the large
veins. It consists of a thick inner layer of connective tissue with elastic fibres,
having intermixed in some veins a transverse layer of muscular fibres ; and an
outer layer consisting of longitudinal elastic lamellae, varying from five to ten in
number, alternating with layers of transverse muscular fibres and connective
tissue, which resembles somewhat in structure the middle coat of large arteries.
In the large veins, as in the commencement of the vena portas, in the upper part
of the abdominal portion of the inferior vena cava, and in the large hepatic
trunks within the liver, the middle coat is thick, and its structure similar to that
of the middle coat in medium-sized veins ; but its muscular tissue is scanty, and
the longitudinal elastic networks less distinctly lamellated. The muscular tissue
of this coat is best marked in the splenic and portal veins, it is absent in certain
parts of the vena cava below the liver, and wanting in the subclavian vein and
terminal parts of the two cavae.
The external coat is usually the thickest, increasing in thickness with the size
of the vessel ; it is similar in structure to the external coat of arteries, but its
chief peculiarity is that in some veins it contains a longitudinal network of mus-
cular fibres. In the smallest veins, it consists of a thick layer of nucleated con-
nective tissue. In medium-sized veins, it is much thicker than the middle^ coat,
and consists of elastic and connective tissues, the fibres of which are longitudinally
arranged. In the largest veins, this coat is from two to five times thicker than
the middle coat, and contains a large number of longitudinal muscular fibres.
This is most distinct in the hepatic part of the inferior vena cava, and at the
termination of this vein in the heart ; in the trunks of the hepatic veins ; in all
the large trunks of the vena portae ; in the splenic, superior mesenteric, external
iliac, renal, and azygos veins. Where the middle coat is absent, this_ muscular
layer extends as far as the inner coat. In the renal and portal veins, it extends
GENERAL ANATOMY. 457
through the whole thickness of the outer coat ; but in the other veins mentioned,
a layer of connective and elastic tissues is found external to the muscular fibres.
All the large veins which open into the heart are covered for a short distance by
a layer of muscular tissue continued on to them from the heart.
Muscular tissue is wanting in the veins : 1. Of the maternal part of the placenta.
2. In most of the cerebral veins and sinuses of the dura mater. 3. In the veins
of the retina. 4. In the veins of the cancellous tissue of bones. 5. In the venous
spaces of the corpora cavernosa. The veins of the above-mentioned parts have
an internal epithelial lining, supported on one or<more layers of areolar tissue.
Most veins are provided with valves, which serve to prevent the reflux of the
blood. They are formed by a reduplication of the middle and inner coats, and
consist of connective tissue and elastic fibres, covered on both surfaces by epithe-
lium ; their form is semilunar. They are attached, by their convex edge, to the
wall of the vein ; the concave margin is free, directed in the course of the venous
current, and lies in close apposition with the wall of the vein, as long as the current
of blood takes its natural course ; if, however, any regurgitation takes place, the
valves become distended, their opposed edges are brought into contact, and the
current is intercepted. Most commonly two such valves are found, placed opposite
one another, more especially in the smaller veins, or in the larger trunks at the
point where they are joined by small branches ; occasionally there are three, and
sometimes only one. The wall of the vein, immediately above the point of attach-
ment of each segment of the valve, is expanded into a pouch or sinus, which
gives to the vessel, when injected or distended with blood, a knotted appearance.
The valves are very numerous in the veins of the extremities, especially the lower
ones, these vessels having to conduct the blood against the force of gravity.
They are absent in the very small veins, also in the venae cavse, the hepatic vein,
portal vein and its branches, the renal, uterine, and ovarian veins. A few valves
are found in the spermatic veins, and one also at their point of junction with the
renal vein and inferior vena cava in both sexes. The cerebral and spinal veins, the
veins of the cancellated tissue of bone, the pulmonary veins, and the umbilical
vein and its branches, are also destitute of valves. They are occasionally found,
few in number, in the azygos and intercostal veins.
The veins are supplied with nutrient vessels, vasa vasorum, like the arteries;
but nerves are not generally found distributed upon them. The only vessels upon
which they have at present been traced, are the sinuses of the dura mater ; on the
spinal veins; on the venae cavae; on the common jugular, iliac, and crural veins;
and on the hepatic veins. (Kolliker.)
The veins may be arranged into three groups: 1. Those of the head and neck,
upper extremity, and thorax, which terminate in the superior vena cava. 2. Those
of the lower extremity, pelvis, and abdomen, which terminate in the inferior vena
cava. 3. The cardiac veins, which open directly into the right auricle of the heart.
VEINS OF THE HEAD AND NECK, UPPER EXTREMITY, AND
THORAX.
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. 2. The veins of the neck. 3. The veins of
the diploe and interior of the cranium.
1. Veins of the Exterior of the Head.
The Veins of the Exterior of the Head are the
Facial. Temporo-m axillary.
Temporal. Posterior auricular.
Internal Maxillary. Occipital.
458
VEINS.
The Facial Vein passes obliquely across the side of the face, extending from
the inner angle of the orbit, downwards and outwards, to the anterior margin of
the Masseter muscle. It lies to the outer side of the facial artery, and is not so
tortuous as that vessel. It commences in the frontal region, where it is called the
frontal vein; at the inner angle of the eye it has received the name of the angular
vein; and from this point to its termination, the facial vein.
Fig. 236.*- Veins of the Head and Neck.
Lingual
laryngeal
The frontal vein commences on the anterior part of the skull, by a venous
plexus, which communicates with the anterior branches of the temporal vein ; the
veins converge to form a single trunk, which descends along the 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 trunk, called the nasal arch. Occasionally the frontal
veins join to form a single trunk which bifurcates at the root of the nose into the
two angular veins. At the nasal arch the branches diverge, and run along the side
of the root of the nose. The frontal vein, as it descends upon the forehead,
receives the supra-orbital vein ; the dorsal veins of the nose terminate in the nasal
OF THE HEAD. 459
arch ; and the angular vein receives, on its inner side, the veins of the ala nasi,
on its outer side the superior palpebral veins ; it moreover communicates with
the ophthalmic vein, which establishes an important anastomosis between this
vessel and the cavernous sinus.
The facial vein commences at the inner angle of the orbit, being a continuation
of the angular vein. It passes obliquely downwards and outwards, beneath the
great Zygomatic muscle, descends along the anterior border of the Masseter, crosses
over the body of the lower jaw, with the facial artery, and, passing obliquely out-
wards and backwards, beneath the Platysma and cervical fascia, unites with a
branch of communication from the temporo-maxillary vein, to form a trunk of
large size which enters the internal jugular.
Branches. The facial vein receives, near the angle of the mouth, communica-
ting branches from the pterygoid plexus. It is also joined by the inferior pal-
pebral, the superior and inferior labial veins, the buccal veins from the cheek, and
the masseteric veins. Below the jaw, it receives the submental, the inferior
palatine, which returns the blood from the plexus around the tonsil and soft
palate, the submaxillary vein, which commences in the submaxillary gland, and,
lastly, the ranine vein.
The Temporal Vein commences by a minute plexus on the side and vertex of
the skull, which communicates with the frontal vein 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, forming the trunk of the vein. This trunk is joined in this situation
by a large vein, the middle temporal, which receives the blood from the substance
of the Temporal muscle and pierces the fascia at the upper border of the zygoma.
The temporal vein then 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.
Branches. The 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, from the side of
the face.
The Internal Maxillary Vein is a vessel of considerable size, receiving branches
which correspond with those derived from the internal maxillary artery. Thus
it receives the middle meningeal veins, the deep temporal, the pterygoid, masse-
teric, buccal, some palatine veins, and the inferior dental. These branches
form a large plexus, the pterygoid, which is placed between the Temporal and
External pterygoid, and partly between the Pterygoid muscles. This plexus
communicates very freely with the facial vein, and with the cavernous sinus, by
branches through the base of the skull. The trunk of the vein then passes
backwards, behind the neck of the lower jaw, and unites with the temporal vein,
forming the temporo-maxillary.
The Temporo-maxillary Vein, formed by the union of the temporal and in-
ternal maxillary vein, descends in the substance of the parotid gland, between
the ramus of the jaw and the Sterno-mastoid muscle, and divides into two
branches, one of which passes inwards to join the facial vein, the other is con-
tinuous with the external jugular. It receives near its termination the posterior
auricular vein.
The Posterior Auricular Vein commences upon the side of the head, by a plexus
which communicates with the branches of the temporal and occipital veins ; de-
scending behind the external ear, it joins the temporo-maxillary, just before that
vessel terminates in the external jugular. This vessel receives the stylo-mastoid
vein, and some branches from the back part of the external ear.
The Occipital Vein commences at the back part of the vertex of the skull, by
a plexus in a similar manner with the other veins. It follows the course of the
occipital artery, passing deeply beneath the muscles of the back part of the neck,
and terminates in the internal jugular, occasionally in the external jugular. As
4G0 VEINS.
this vein passes opposite the mastoid process, it receives the mastoid vein, which
establishes a communication with the lateral sinus.
2. Yeins of the Neck.
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 receives the greater part of the blood from the
exterior of the cranium and deep parts of the face, being a continuation of the
temporo-maxillary and posterior auricular veins. It commences in the substance
of the parotid gland, on a level with the angle of the lower jaw, and runs perpen-
dicularly 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 the internal jugular. As it descends the neck, it is
separated from the Sterno-mastoid by the anterior layer of the deep cervical
fascia, and is covered by the Platysma, the superficial fascia, and the integument.
This vein is crossed about its centre by the superficial cervical nerve, and its
upper half 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. These valves do not prevent
the regurgitation of the blood, or the passage of injection from below upwards.1
Branches. This vein receives the occipital, the posterior external jugular, and,
near its termination, the supra-scapular and transverse cervical veins. It com-
municates 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 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 descends the back part of the neck, and
opens into the external jugular just below the middle of its course.
The Anterior Jugular Vein collects the blood from the integument and muscles
in the middle of the anterior region of the neck. 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 subclavian vein, near the
termination of the external jugular. This vein varies considerably in size, bear-
ing 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 branches, and occasionally an inferior thyroid vein.
Just above the sternum, the two anterior jugular veins communicate by a trans-
verse trunk, which receives branches from the inferior thyroid veins. It also
communicates with the external and with the internal jugular. There are no
valves in this vein.
The Internal Jugular Vein collects the blood from the interior of the cra-
nium, from the superficial parts of the face, and from the neck. It commences
at the jugular foramen, in the base of the skull, being formed by the coalescence
of the lateral and inferior petrosal sinuses. At its origin it is somewhat dilated,
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.
OF THE NECK. 4G1
and this dilatation is called the sinus, or gulf of the internal jugular vein. It
runs down the side of the neck in a vertical direction, lying at first on the outer
side of the internal carotid, and then on the outer side of the common carotid,
and at the root of the neck unites with the subclavian vein, to form the vena in-
nomiuata. The internal jugular vein, at its commencement, lies upon the Rectus
lateralis, behind, and at the outer side of the internal carotid, and the eighth and
ninth pairs of nerves ; lower down, the vein and artery lie upon the same plane,
the glosso-pharyngeal and hypoglossal nerves passing forwards between them ;
the pneumogastric descends between and behind them, in the same sheath, and
the spinal accessory passes obliquely outwards, behind 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 crosses it at its lower part. The vein is of considera-
ble size, but it varies in different individuals, the left one being usually the
smallest. It is provided with a pair of valves, which are placed at its point of
termination, or from half to three-quarters of an inch above it.
Branches. This vein receives in its course the facial, lingual, pharyngeal,
superior and middle thyroid veins, and the occipital. At its point of junction
with the branch common to the temporal and facial veins, it becomes greatly
increased in size.
The lingual veins commence on the dorsum, sides, and under surface of the
tongue, and passing backwards, following the course of the lingual artery and its
branches, terminate in the internal jugular.
The pharyngeal vein commences in a minute plexus, the pharyngeal, at the
back part and sides of the pharynx, and after receiving meningeal branches, and
the Vidian and spheno-palatine veins, terminates in the internal jugular. It occa-
sionally opens into the facial, lingual, or superior thyroid vein.
The superior thyroid vein commences in the substance and on the surface of the
thyroid gland, by branches corresponding with those of the superior thyroid artery,
and terminates in the upper part of the internal jugular vein.
The middle thyroid vein collects the blood from the lower part of the lateral lobe
of the thyroid gland, and, being joined by some branches from the larynx and
trachea, terminates in the lower part of the internal jugular vein.
The Vertebral Vein commences by numerous small branches in the occipital
region, from the deep muscles at the upper and back part of the neck, passes out-
wards, and enters the foramen in the transverse process of the atlas, and descends
by the side of the vertebral artery, in the canal formed by the transverse processes
of the cervical vertebras. Emerging from the foramen in the transverse process of
the sixth cervical, it 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.
This vein, in the lower part of its course, occasionally divides into two branches ;
one emerges with the artery at the sixth cervical vertebra, the other escapes
through the foramen in the seventh cervical.
Branches. This vein receives in its course the posterior condyloid vein, mus-
cular branches 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 ; and, lastly, the ascending and deep cervical
veins.
3. Veins of the Diploe and Interior of the Cranium.
Veins of the Diploe.
The diploe of the cranial bones is channelled, in the adult, with a number of
tortuous canals, 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 epithelium, resting upon a layer of elastic tissue, and they
present, at irregular intervals, pouch-like dilatations or culs-de-sac, which serve
462 VEINS.
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 united,
they communicate with each other, and increase in size. These vessels commu-
nicate, in the interior of the cranium, with the meningeal veins, and with the
sinuses of the dura mater, and, on the exterior of the skull, with the veins of the
pericranium. They are divided into the frontal, which opens into the supra-orbital
Fig. 237. — Veins of the Diploe, as displayed \>j the Removal of the
Outer Table of the Skull.
vein, by an aperture at the supra-orbital notch ; the anterior temporal, which is
confined chiefly to the frontal bone, and opens into one of the deep temporal veins,
after escaping by an aperture in the great wing of the sphenoid ; the posterior
temporal, which is confined to the parietal bone, and terminates in the lateral sinus
by an aperture at the posterior inferior angle of the parietal bone ; and the occipital,
which is confined to the occipital bone, and opens either into the occipital vein,
or the occipital sinus.
Cerebral Veins.
The Cerebral Veins are remarkable for the extreme thinness of their coats, from
the muscular tissue in them being wanting, and for the absence of valves. They
may be divided into two sets, the superficial, which are placed on the surface, and
the deep veins, which occupy the interior of the organ.
The Superficial Cerebral Veins ramify upon the surface of the brain, being
lodged in the sulci, between the convolutions, a few running across the convolu-
tions. They receive branches from the substance of the brain, and terminate in
the sinuses. They are named from the position they occupy, superior, inferior,
internal, and external.
The Superior Cerebral Veins, seven or eight in number on each side, pass
forwards and inwards towards the great longitudinal fissure, where they receive
the internal cerebral veins, which return the blood from the convolutions of the
flat surface of the corresponding hemisphere ; passing obliquely forwards, they
become invested with a tubular sheath of the arachnoid membrane, and open into
CEREBRAL. 4G3
the superior longitudinal sinus, in the opposite direction to the course of the
blood.
The Inferior Anterior Cerebral Veins commence on the under surface of the
anterior lobes of the brain, and terminate in the cavernous sinuses.
The Inferior Lateral Cerebral Veins commence on the lateral parts of the
hemispheres and at the base of the brain : they unite to form from three to five
veins, which open into the lateral sinus from before backwards.
The Inferior Median Cerebral Veins, which are very large, commence at the
fore part of the under surface of the cerebrum, and from the convolutions of the
posterior lobe, and terminate in the straight sinus behind the venae Galeni.
The Deep Cerebral or Ventricular Veins (venae Galeni) are two in number,
one from the right ventricle, the other from the left. They are each formed
by two veins, the vena corporis striati and the choroid vein. They pass back-
wards, parallel with one another, inclosed within the velum interpositum, and
pass out of the brain at the great transverse fissure, between the under surface
of the corpus callosum and the tubercula quadrigemina, and enter the straight
sinus.
The vena corporis striati commences in the groove between the corpus striatum
and thalamus opticus, receives numerous veins from both of these parts, and
unites behind the anterior pillar of the fornix with the choroid vein, to form one
of the venae Galeni.
The choroid vein runs along the whole length of the outer border of the
choroid plexus, receiving veins from the hippocampus major, the fornix and
corpus callosum, and unites; at the anterior extremity of the choroid plexus,
with the vein of the corpus striatum.
The Cerebellar Veins occupy the surface of the cerebellum, and are disposed in
three sets, superior, inferior, and lateral. The superior pass forwards and inwards,
across the superior vermiform process, and terminate in the straight sinus ; some
open into the venae Galeni. The inferior cerebellar veins, of large size, run
transversely outwards, and terminate by two or three trunks in the lateral sinuses.
The lateral anterior cerebellar veins terminate in the superior petrosal sinuses.
Sinuses of the Dura Mater.
The sinuses of the dura mater are venous channels, analogous to the veins,
their outer coat being formed by the dura mater ; their inner, by a continuation
of the serous membrane of the veins. They are twelve in number, and are
divided into two sets: — 1. Those situated at the upper and back part of the skull.
2. The sinuses at the base of the skull.
1. The sinuses of the upper and back part are the
Superior longitudinal. Straight sinus.
Inferior longitudinal. Lateral sinuses.
Occipital sinuses.
The Superior Longitudinal Sinus occupies the attached margin of the falx
cerebri. Commencing at the crista Galli, it runs from before backwards, groov-
ing 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 dividing into the two lateral sinuses. This sinus is triangular in form,
narrow in front, and gradually increasing in size as it passes backwards. On
examining its inner surface, it presents the internal openings of the cerebral
veins : these vessels are, for the most part, directed from behind forwards, and
chiefly open at the back part of the sinus, their orifices being concealed by fibrous
areolae; numerous fibrous bands, chordse Willisii, are also seen, which extend
transversely across its inferior angle ; and lastly, some small, white, projecting
bodies, the glandulae Pacchioni. This sinus receives the superior cerebral veins.
464
VEINS.
numerous veins from the diploe and dura mater, and, at the posterior extremity
of the sagittal suture, the parietal veins from the pericranium.
The point where the superior longitudinal and lateral sinuses are continuous is
called the confluence of the sinuses or the torcular Herophili. It presents a con-
siderable dilatation, of very irregular form, and is the point of meeting of six
sinuses, the superior longitudinal, the two lateral, the two occipital, and the
straight.
The Inferior Longitudinal Sinus, more correctly described as the inferior
longitudinal vein, is contained in the posterior part of the free margin of the falx
cerebri. It is of a circular form, increases in size as it passes backwards, and
terminates in the straight sinus. It receives several veins from the falx cerebri,
and occasionally a few from the flat surface of the hemispheres.
The Straight Sinus is situated at the line of junction of the falx cerebri with
the tentorium. It is triangular in form, increases in size as it proceeds back-
wards, and runs obliquely downwards and backwards from the termination of the
inferior longitudinal sinus to the torcular Herophili. Besides the inferior lon-
gitudinal sinus, it receives the venae Galeni, the inferior median cerebral veins,
and the superior cerebellar. A few transverse bands cross its interior.
Fig. 238. — Vertical Section of the Skull, showing the Sinuses of the Dura Mater.
Toreular_
Herophili
The Lateral Sinuses are of large size, and situated in the attached margin of
the tentorium cerebelli. They commence at the torcular Herophili, and, passing
horizontally outwards to the base of the petrous portion of the temporal bone,
curve downwards and inwards on each side to reach the jugular foramen, where
they terminate in the internal jugular vein. Each sinus rests, in its course, upon
the inner surface of the occipital bone, the posterior inferior angle of the parietal, the
mastoid portion of the temporal, and on the occipital again just before its termi-
nation. These sinuses are of unequal size, the right being the larger, and they
increase in size as they proceed from behind forwards. The horizontal portion is
of a triangular form, the curved portion semi -cylindrical ; their inner surface is
smooth, and not crossed by the fibrous bands found in the other sinuses. These
sinuses receive blood from the superior longitudinal, the straight, and the occipital
sinuses ; and in front they communicate with the superior and inferior petrosal.
They communicate with the veins of the pericranium by means of the mastoid
and posterior condyloid veins, and they receive the inferior cerebral and inferior
cerebellar veins, and some from the diploe.
The Occipital are the smallest of the cranial sinuses. They are usually two in
ruimber, and situated in the attached margin of the falx cerebelli. They commence
SINUSES OF THE DURA MATER.
46(
by several small veins around the posterior margin of the foramen magnum, which
communicate with the posterior spinal veins, and terminate by separate openings
(sometimes by a single aperture) in the torcular Herophili.
2. The sinuses at the base of the skull are the
Cavernous.
Circular.
Transverse.
Inferior petrosal.
Superior petrosal.
The Cavernous Sinuses are named from their presenting a reticulated structure.
They are two in number, of large size, and placed one on each side of the sella
Turcica, extending from the sphenoidal fissure to the apex of the petrous portion
Fig. 239.— The Sinuses at the Base of the Skull.
of the temporal bone : they receive anteriorly the ophthalmic vein through the
sphenoidal fissure, communicate behind with the petrosal sinuses, and with each
other by the circular and transverse sinuses. On the inner wall of each sinus is
found the internal carotid artery, accompanied by filaments of the carotid plexus
and by the sixth nerve ; and on its outer wall, the third, fourth, and ophthalmic
nerves. These parts are separated from the blood flowing along the sinus by the
lining membrane, which is continuous with the inner coat of the veins. The
cavity of the sinus, which is larger behind than in front, is intersected by filaments
of fibrous tissue and small vessels. The cavernous sinuses receive the inferior
anterior cerebral veins; they communicate with the lateral sinuses by means
of the superior and inferior petrosal, and with the facial vein through the
ophthalmic.
The ophthalmic is a large vein, which connects the frontal vein at the inner
angle of the orbit with the cavernous sinus ; it pursues the same course as the
ophthalmic artery, and receives branches corresponding to those 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.
The Circular Sinus completely surrounds the pituitary body, and communicates
on each side with the cavernous sinuses. Its posterior half is larger than the
30
466
VEINS,
Fig. 240.— The Superficial Veins of the
Upper Extremity.
anterior ; and in old age it is more capacious than at an early period of life. It
receives veins from the pituitary body, and from the adjacent bone and dura mater.
The Inferior Petrosal Sinus is situated in
the groove formed by the junction of the
inferior border of the petrous portion of the
temporal with the basilar process of the
occipital. It commences in front at the
termination of the cavernous sinus, and opens
behind into the jugular foramen, forming
with the lateral sinus the commencement of
the internal jugular vein. These sinuses
are semi-cylindrical in form.
The Transverse Sinus is placed trans-
versely across the fore part of the basilar
process of the occipital bone, serving to
connect the two inferior petrosal and cavern-
ous sinuses. A second is occasionally found
opposite the foramen magnum.
The Superior Petrosal Sinus is situated
along the upper border of the petrous por-
tion 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 a cerebral vein (inferior
lateral cerebral) from the under part of the
middle lobe, and a cerebellar vein (anterior
lateral cerebellar) from the anterior border
of the cerebellum.
IZeitanCejjXaJt'c,
External ,
CulaMCoutNi rwt
Veins of the Upper Extremity
and Thorax.
The veins of the upper extremity are
divided into two sets: 1. The superficial
veins. 2. The deep veins.
The Superficial Veins are placed imme-
diately beneath the integument between the
two layers of superficial fascia ; they com-
mence in the hand chiefly on its dorsal
aspect, where they form a more or less com-
plete arch.
The Deep Veins accompany the arteries,
and constitute the venas comites of those
vessels.
Both sets of vessels are provided with
valves, which are more numerous in the deep
than in the superficial.
1. The Superficial Veins of the Upper
Extremity are the
Anterior ulnar.
Posterior ulnar.
Basilic.
Eaclial.
The Anterior Ulnar
Cephalic.
Median.
Median basilic.
Median cephalic.
Vein commences on
the anterior surface of the wrist and ulnar
side of the hand, and ascends along the
•
OF THE UPPER EXTREMITY. 467
inner side of the forearm to the bend of the elbow, where it joins with the posterior
ulnar vein to form the basilic. It communicates with branches of the median
vein in front, and with the posterior ulnar behind.
The Posterior Ulnar Vein commences on the posterior surface of the ulnar
side of the hand, and from the vein of the little finger (vena salvatella), situated
over the fourth metacarpal space. It ascends 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 basilic.
The Basilic is a vein of considerable size, formed by the coalescence of the
anterior and posterior ulnar veins ; ascending along the inner side of the elbow, it
receives the median basilic vein, and, passing upwards along the inner side of the
arm, pierces the deep fascia, and ascends in the course of the brachial artery, ter-
minating either in one of the venae comites of that vessel, or in the axillary vein.
The Radial Vein commences from the dorsal surface of the thumb, index finger,
and radial side of the hand, by branches which communicate with the vena salva-
tella. They form by their union a large vessel, which ascends along the radial
side of the forearm, receiving numerous branches from both its surfaces. At the
bend of the elbow it receives the median cephalic, when it becomes the cephalic
vein.
The Cephalic Vein ascends along the outer border of the Biceps muscle, to the
upper third of the arm ; it then passes in the interval between the Pectoralis major
and Deltoid muscles, accompanied by the descending branch of the thoracica acro-
mialis artery, and terminates 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 upwards in front of the clavicle.
The Median Vein collects the blood from the superficial structures in the palmar
surface of the hand and middle line of the forearm, communicating with the
anterior ulnar and radial veins. At the bend of the elbow, it receives a branch of
communication from the deep veins, accompanying the brachial artery, and divides
into two branches, -the median cephalic and median basilic, which diverge from
each other as they ascend.
The Median Cephalic, the smaller of the two, passes outwards in the groove
between the Supinator longus and Biceps muscles, and joins with the cephalic
vein. The branches of the external cutaneous nerve pass behind this vessel.
The Median Basilic vein passes obliquely inwards, in the groove between the
Biceps and Pronator radii teres, and joins with the basilic. This vein passes
in front of the brachial artery, from which it is separated by a fibrous expansion,
given off from the tendon of the Biceps to the fascia covering the Flexor muscles
of the forearm. Filaments of the internal cutaneous nerve pass in front of as well
as behind this vessel.
2. The Deep Veins of the Upper Extremity follow the course of the arteries,
forming their vena3 comites. They are generally two in number, one 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 superficial palmar veins. Branches from these vessels
on the radial side of the hand accompany the superficialis vola3, and on the ulnar
side terminate in the deep ulnar veins. The deep ulnar veins, as they pass in
front of the wrist, communicate with the interosseous and superficial veins, and
unite at the elbow with the deep radial veins, to form the vense comites of the
brachial artery.
The Interosseous Veins 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 venoa
comites of the ulnar artery.
4G8 VEINS.
The Deep Palmar Veins accompany the deep palmar arch, being formed bv
branches which accompany the ramifications of this vessel. They communicate
with the superficial palmar veins at the inner side of the hand ; and, on the outer
side, terminate in the venaa comites of the radial artery. At the wrist, they receive
a dorsal and a palmar branch from the thumb, and unite with the deep radial
veins. Accompanying the radial artery, these vessels terminate in the vense
comites of the brachial artery.
The Brachial Veins are placed one on each side of the brachial artery, receiving
branches corresponding with those given off from this vessel ; at the lower margin
of the axilla they unite with the basilic to form the axillary vein.
The deep veins have numerous anastomoses, not only with each other, but also
with }he superficial veins.
The Axillary Yein is of large size and formed by the continuation upwards
of the basilic vein. It commences at the lower part of the axillary space, and
increasing in size as it ascends, by receiving branches corresponding with those of
the axillary artery, terminates immediately beneath the clavicle at the outer mar-
gin of the first rib, and becomes the subclavian vein. This vessel is covered in
front by the Pectoral muscles and costo-coracoid membrane, and lies on the thoracic
side of the axillary artery. Opposite the Subscapularis, it is joined by a large
vein, formed by the junction of the vense comites of the brachial ; and near its
termination it receives 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 Subclavian Yein, the continuation of the axillary, extends from the outer
margin of the first rib to the inner end of the sterno-clavicular articulation, where
it unites with the internal jugular, to form the vena innominata. It is in relation,
in front, with the clavicle and Subclavius muscle ; behind, with the subclavian
artery, from which it is separated internally by the Scalenus anticus and phrenic
nerve. Below, it rests in a depression on the first rib and upon the pleura.
Above, it is covered by the cervical fascia and integument.
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 the
latter behind the Scalenus anticus. This vessel is provided with valves about an
inch from its termination in the innominate, just external to the entrance of the
external jugular vein.
Branches. It receives the external and anterior jugular veins and a small branch
from the cephalic, outside the Scalenus; and on the inner side of this muscle, the
internal jugular veins.
The YENiE Innominate (fig. 241) 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 Bight Vena Innominata is a short vessel, about an inch and a half in length,
which commences at the inner end of the clavicle, and, passing almost vertically
downwards, joins with the left vena innominata just below the cartilage of the first
rib, to form the superior vena cava. It lies superficial and external to the arteria
innominata ; on its right side the pleura is interposed between it and the apex of
the lung. This vein, at its angle of junction with the subclavian, receives the
right vertebral vein, and right lymphatic duct ; and, lower down, the right internal
mammary, right inferior thyroid, and right superior intercostal veins.
The Left Vena Innominata, about three inches in length, and larger than the
right, passes obliquely from right to left across the upper and front part of the
chest, to unite with its fellow of the opposite side, forming the superior vena cava.
It is in relation, in front, with the sternal end of the left clavicle, the left sterno-
clavicular articulation, and 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
INNOMINATE.
469
three large arteries arising from the arch of the aorta. This vessel is joined "by
the left vertebral, left inferior thyroid, left internal mammary, and the left supe-
rior intercostal veins, and
occasionally some thymic
and pericardiac veins. Fis- 241--TJ1Ie 7e"ffi Ca™ a"d AzP°9 Veins'
" , " ... with their Formative Branches.
There are no valves in the '„ A T /
\\3.~-^AnUrior Jugular*
venas mnominatoe.
Peculiarities. Sometimes
the innominate veins open se-
parately into the right auri-
cle ; in such cases the right
vein takes the ordinary course
of the superior vena cava, but
the left vein, after communi-
cating 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 of
the veins in the adult is a
regular one in the foetus at an
early period, and the two ves-
sels are persistent in birds
and some mammalia. The
subsequent changes which
take place in these vessels are
the following : The communi-
cating branch between the two
trunks enlarges and forms the
future left innominate vein ;
the remaining part of the left
trunk is obliterated as far
as the heart, where it remains
pervious, and forms the coro-
nary sinus ; a remnant of the
obliterated vessel is seen in
adult life as a fibrous band
passing along the back of the
left auricle and in front of the
root of the left lung, called, by
Mr. Marshall, the vestigial fold
of the pericardium.
The internal mammary
veins, two in number to
each artery, follow the
course of that vessel, and
receive branches corre-
sponding with those de-
rived from it. The two
veins unite into a single
trunk, which terminates
in the innominate vein.
The inferior thyroid
veins, two, frequently three
or four in number, arise
in the venous plexus, on
the thyroid body, commu-
nicating with the middle
and superior thyroid veins.
The left one descends in
Superior Thyroid
WLJJlt
'vntal Jugular
4T0 VEINS.
front of the trachea, behind the Sterno-thyroid muscles, communicating with ita
fellow by transverse branches, and terminates in the left vena innominata. The
right one, which is placed a little to the right of the median line, opens into the
right vena innominata, just at its junction with the superior cava. These veins
receive tracheal and inferior laryngeal branches, and are provided with valves at
their termination in the innominate veins.
The Superior Intercostal Veins return the blood from the upper intercostal
spaces.
The rigid superior intercostal, much smaller than the left, closely corresponds
with the superior intercostal artery, receiving the blood from the first, or first and
second intercostal spaces, and terminates in the right vena innominata. Some-
times it passes down, and opens into the vena azygos major.
The left superior intercostal is always larger than the right, but varies in size in
different subjects, being small when the left upper azygos vein is large, and vice
versa. It is usually formed by branches from the two or three upper intercostal
spaces, and, passing across the arch of the aorta, terminates in the left vena inno-
minata. The left bronchial vein opens into it.
The Superior Vena Cava 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 venae innominatae. It commences immediately below the cartilage of the
first rib on the right side, and, descending vertically downwards, enters the peri-
cardium about an inch and a half above the heart, and terminates in the upper
part of the right auricle. In its course, it describes a slight curve, the convexity of
which is turned to the right side.
Relations. In front, with the thoracic fascia, which separates it from the thymus
gland, and from the sternum ; behind, with the root of the right lung. On its
right side, with the phrenic nerve and the pleura of the right side ; on its left
side, with the ascending part of the aorta. The portion contained within the
pericardium 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 peri-
cardium, and several small veins from the pericardium and parts in the medias-
tinum. The superior vena cava has no valves.
The Azygos Veins connect together the superior and inferior venae cavae,
supplying the place of these vessels in that part of the trunk in which they are
deficient, on account of their connection with the heart.
The larger, the right azygos vein, commences opposite the first or second lumbar
vertebra, by receiving a branch from the right lumbar veins ; sometimes by a
branch from the renal vein, or from the inferior vena cava. It enters the thorax
through the aortic opening in the Diaphragm, and passes along the right side of
the vertebral column to the third dorsal vertebra, where it arches forward, over
the root of the right lung, and terminates in the superior vena cava, just before
that vessel enters the pericardium. Whilst passing through the aortic opening
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, covered by the pleura.
Branches. It receives nine or ten lower intercostal veins of the right side, the
vena azygos minor, several oesophageal, mediastinal, and vertebral veins ; near its
termination, the right bronchial vein ; and it is occasionally connected with the
right superior intercostal vein. A few imperfect valves are found in this vein ;
but its branches are provided with complete valves.
The intercostal veins on the left side, below the two or 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 commences in the lumbar region, by a
branch from one of the lumbar veins, or from the left renal. It passes into the
thorax, through the left crus of the Diaphragm, and, ascending on the left side of
AZYGOS— SPINAL. 471
the spine, as high as the sixth or seventh vertebra, passes across the column,
behind the aorta and thoracic duct, to terminate in the right azygos vein. It
Teceives the four or five lower intercostal veins of the left side, and some oesopha-
geal and mediastinal veins.
The left upper azygos vein varies according to the size of the left superior
intercostal. It receives veins from the intercostal spaces between the left superior
intercostal vein, and highest branch of the left lower azygos. They are usually
two or three in number, and join to form a trunk which ends in the right azygos
vein, or in the left lower azygos. When this vein is small, or altogether wanting,
the left superior intercostal vein will extend as low as the fifth or sixth intercostal
space.
The bronchial veins return the blood from the substance of the lungs ; that of
the right side opens into the vena azygos major, near its termination ; that of the
left side, in the left superior intercostal vein.
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 (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 vertebrae {vense basis vertebrarum).
4. The veins of the spinal cord {medulli- spinal veins).
1. The Dorsi-spinal Veins 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 form a complicated network, which surrounds the
spinous processes, laminae, and the transverse and articular processes of 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 per-
forate the ligamenta subflava; in the intervals between the arches of the vertebrae,
they terminate in the vertebral veins in the neck, in the intercostal veins in the
thorax, in the lumbar and sacral veins in the loins and pelvis.
2. The veins contained in the spinal canal are situated between the theca
vertebralis and the vertebrae. They consist of two longitudinal plexuses, one
of which runs along the posterior surface of the bodies of the vertebrae,
throughout the entire length of the spinal canal {anterior longitudinal spinal veins),
receiving the veins belonging to the bodies of the vertebrae (venae basis verte-
brarum). The other plexus {posterior longitudinal spinal veins) is placed on the
inner or anterior surface of the laminae of the vertebrae, and extends also along
the entire length of the spinal canal.
The Anterior Longitudinal Spinal Veins consist of two large, tortuous venous
canals, which extend along the whole length of the vertebral column, from the
foramen magnum to the base of the coccyx, being placed one on each side of the
posterior surface of the bodies of the vertebrae, external to the posterior common
ligament. These veins communicate together opposite each vertebra, by transverse
trunks, which pass beneath the ligament, and receive the large venae basis verte-
brarum, from the interior of the body of each 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 dorsal 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 either side, between the inner surface of the laminae and the theca verte-
bralis. They communicate, like the anterior, opposite each vertebra, by transverse
472
VEINS.
trunks ; and with the anterior longitudinal veins, by lateral transverse branches
which pass from behind forwards. These veins, at the intervertebral foramina,
join with the dorsi-spinal veins.
Fig. 242. — Transverse Section of a Dorsal Vertebra, showing the Spinal Veins.
3. The Veins of the Bodies of the Vertebrse (venae basis vertebrarum) emerge
from the foramina on their posterior surface, 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, arise from the entire circumference of the vertebra,
communicate with veins which enter through the foramina, on the anterior surface
of the bodies, and converge to the principal canal, which is sometimes double
towards its posterior part. They become greatly developed in advanced age.
Fig. 243. — Vertical Section of two Dorsal Vertebrje, showing the Spinal Veins. .
4. The Veins of the Spinal Cord (medulli-spinal) consist of a minute tortuous
venous plexus, which covers the entire surface of the cord, being situated between
the pia mater and arachnoid. These vessels emerge chiefly from the posterior
median furrow, and are largest in the lumbar region. Near the base of the skull
they unite, and form two or three small trunks, which communicate with the ver-
tebral veins, and then terminate in the inferior cerebellar veins, or in the petrosal
sinuses. Each of the spinal nerves is accompanied by a branch as far as the in-
tervertebral foramina, where they join the other veins from the spinal canal.
There are no valves in the spinal veins.
OF THE LOWER EXTREMITY.
IVi
VEINS OF THE LOWER EXTREMITY.
Fig. 244.— The Internal or
Long Saphenous Vein
and its Branches.
\
-r\4
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 integu-
ment, between the two layers of superficial fascia,
the deep veins accompanying the arteries, and form-
ing the vena? comites of those vessels. Both sets of
veins are provided with valves, which are more nu-
merous in the deep than in the superficial set. These
valves are also more numerous in the lower than in
the upper limbs.
The Superficial Veins of the lower extremity
are the internal or long saphenous, and the external
or short saphenous.
The internal saphenous vein (fig. 244) com-
mences from a minute plexus, which covers the
dorsum and inner side of the foot; it ascends in
front of the inner ankle, 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 backwards 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, an inch and a half below Poupart's ligament.
This vein receives in its course cutaneous branches
from the leg and thigh, and, at the saphenous open-
ing, 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 a
large branch ; so that occasionally three large veins
are seen converging from different parts of the thigh
towards 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 ante-
rior 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 is formed
by branches which collect the blood from the
dorsum and outer side of the foot ; it ascends behind
the outer ankle, 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. Ascending directly upwards,
it perforates the deep fascia in the lower part of
the popliteal space, and terminates in the popliteal
vein, between the heads of the Gastrocnemius muscle.
It is accompanied by the external saphenous nerve.
m
474
VEINS.
Fig. 245.
-External or Short Saphe-
nous Vein.
It receives numerous large branches from the back part of the leg, and communicatee
with the deep veins on the dorsum of the foot, and
behind the outer malleolus. This vein has only
two valves, one of which is always found near its
termination in the popliteal vein.
The Deep Veins of the lower extremity accom-
pany the arteries and their branches, and are called
the vense comites of those vessels.
The external and internal plantar veins unite to
form the posterior tibial. They accompany the
posterior tibial artery, and are joined by the pero-
neal veins.
The anterior tibial veins are formed by a continua-
tion upwards of the venae dorsales pedis. They
perforate the interosseous membrane at the upper
part of the leg, and form, by their junction with the
posterior tibial, the popliteal vein.
The valves in the deep veins are very nume-
rous.
The Popliteal Vein" is formed by the junction
of the venae comites of the anterior and posterior
tibial vessels; it ascends through the popliteal
space to the tendinous 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 its outer side. It receives the
sural veins from the Gastrocnemius muscle, the
articular veins, and the external saphenous. The
valves in this vein are usually four in number.
The Femoral Yein 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 beneath
Poupart's ligament, it lies to its inner side, and on
the same plane as that vessel. It receives numerous
muscular branches; the profunda femoris joins it
about an inch and a half below Poupart's ligament,
and near its termination the internal saphenous vein. The valves in this vein are
four or five in number.
The External Iliac Vein commences at the termination of the femoral, be-
neath the crural arch, and, passing upwards along the brim of the pelvis, terminates
opposite the sacro-iliac symphysis, 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 upwards, gradually inclines behind it. On
the left side, it lies altogether on the inner side of the artery. It receives, imme-
diately above Poupart's ligament, the epigastric and circumflex iliac veins. It
has no valves.
The Internal Iliac Vein is formed by the venae comites of the branches of
the internal iliac artery, the umbilical arteries excepted. 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 hemorrhoidal and
vesico-prostatic plexuses in the male, and the 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
ILIAC— INFERIOR VENA CAVA. 475
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 hemorrhoidal plexus surrounds the lower end of the rectum, being formed
by the superior hemorrhoidal veins, branches of the inferior mesenteric, and the
middle and inferior hemorrhoidal, which terminate in the internal iliac. The
portal and general venous systems have a free communication by means of the
branches composing this plexus.
The vesico-prostatic plexus surrounds the neck and base of the bladder and
prostate gland. It communicates with the hemorrhoidal plexus behind, and
receives the dorsal vein of the penis, which enters the pelvis beneath the sub-
pubic ligament. This plexus is supported upon the sides of the bladder by a
reflection of the pelvic fascia. The veins composing it are very liable to become
varicose, and often contain hard earthy concretions, called phlebolites.
The dorsal vein of the penis is a vessel of large size, which returns the blood
from the body of this organ. At first it consists of two branches, which are con-
tained in the groove on the dorsum of the penis, and receives veins from the
glans, the corpus spongiosum, and numerous superficial veins ; these unite near
the root of the penis into a single trunk, which pierces the triangular ligament
beneath the pubic arch, and divides into two branches, which enter the prostatic
plexus.
The vaginal plexus surrounds the mucous membrane of the vagina, being espe-
cially developed at the orifice of this canal ; it communicates with the vesical
plexus in front, and with the hemorrhoidal plexus behind.
The uterine plexus is situated along the sides and superior angles of the uterus,
receiving large venous canals (the uterine sinuses) from its substance. The veins
composing this plexus anastomose frequently with each other and with the ovarian
veins. They are not tortuous like the arteries.
Each Common Iliac Vein is formed by the union of the external and internal
iliac veins in front of the sacro-vertebral articulation ; passing obliquely upwards
towards the right side, they terminate upon the intervertebral substance between
the fourth and fifth lumbar vertebrae, where they unite at an acute angle to form
the inferior vena cava. The right common iliac 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, longer and more oblique in its course,
is at first situated at the inner side of the corresponding artery, and then behind
the right common iliac. Each common iliac receives the ilio-lumbar, and some-
times the lateral sacral veins. The left one receives, in addition, the middle sacral
vein. No valves are found in these veins.
The middle sacral vein accompanies its corresponding artery along the front of
the sacrum, and terminates in the left common iliac vein; occasionally in the
commencement of the inferior vena cava.
Peculiarities. The left common iliac vein, instead of joining with the right one 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 vena cava. In these cases, the two common iliacs are connected by a small communicating
branch at the spot where they are usually united.
The Inferior Vena Cava 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
vertebras. It passes upwards 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
in its posterior border. It then perforates the tendinous centre of the Diaphragm,
enters the pericardium, where it is covered by its serous layer, 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, which is of large size during fcetal life.
Relations. In front, from below upwards, with the mesentery, transverse por-
476 VEINS.
tion of the duodenum, the pancreas, portal vein, and the posterior border of th?
liver, which partly and occasionally completely surrounds it ; behind, it rests upon
the vertebral column, the right crus of the Diaphragm, the right renal and lumbar
arteries ; on the left side, it is in relation with the aorta. It receives in its course
the following branches : —
Lumbar. Supra-renal.
Eight spermatic. Phrenic.
Renal. Hepatic.
Peculiarities of Position. This vessel is sometimes placed on the left side of the aorta, as
high as the left renal vein, 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 upwards as its termination
in the heart : in such cases, the abdominal and thoracic viscera, together with the great vessels,
are all transposed.
Peculiarities of Termination. Occasionally the inferior vena cava joins the right azygos vein,
which is then of large size. In such cases, the superior cava receives the whole of the blood from
the body before transmitting it to the right auricle, the blood from the hepatic veins excepted,
these vessels terminating directly in the right auricle.
The lumbar veins, three or four in number on each side, collect the blood by
dorsal branches from the muscles and integument of the loins, and by abdominal
branches from the walls of the abdomen, where they communicate with the
epigastric veins. At the spine, they receive branches from the spinal plexuses, and
they pass forwards round the sides of the bodies of the vertebras beneath the Psoas
magnus, and terminate at the back part of the inferior cava. The left lumbar veins
are longer than the right, and pass behind the aorta. The lumbar veins commu-
nicate with each other by branches which pass in front of the transverse processes.
Occasionally two or more of these veins unite to form a single trunk, the ascending
lumbar, which serves to connect the common iliac, ilio-lumbar, lumbar, and azygos
veins of the corresponding side of the body.
The spermatic veins emerge from the back of the testis, and receive branches
from the epididymis ; they form a branched and convoluted plexus, called the
spermatic plexus or plexus pampiniformis, below the abdominal ring. The vessels
composing this plexus are very numerous, and ascend along the cord in front of
the vas deferens ; having entered the abdomen, they coalesce to form two branches,
which ascend on the Psoas muscle, behind the peritoneum, lying one on each side
of the spermatic artery, and unite to form a single vessel, which opens on the right
side in the inferior vena cava, piercing this vessel obliquely; on the left side in the
left renal vein, terminating at right angles with this vein. The spermatic veins
are provided with valves. The left spermatic vein passes behind the sigmoid
flexure of the colon ; this circumstance, as well as the indirect communication of
• the vessel with the inferior vena cava, may serve to explain the more frequent
occurrence of varicocele on the left side.
The ovarian veins are analogous to the spermatic in the male ; they form a
plexus near the ovary, and in the broad ligament and Fallopian tube, communi-
cating with the uterine plexus. They terminate as in the male. Valves are
occasionally found in these veins. These vessels, like the uterine veins, become
much enlarged during pregnancy.
The renal veins are of large size, and placed in front of the divisions of the
renal arteries. The left is longer than the right, and passes in front of the aorta,
just below the origin of the superior mesenteric arter}'-. It receives the left
spermatic and left inferior phrenic veins. It usually opens into the vena cava, a
little higher than the right.
The supra-renal vein terminates, on the right side, in the vena cava ; on the left
side, in the left renal or phrenic vein.
The phrenic veins follow the course of the phrenic arteries. The two superior,
of small size, accompany the corresponding nerve and artery; the right terminating
PORTAL SYSTEM. 47T
opposite the junction of the two venae innominate, the left in the left superior
intercostal or left internal mammary. The two inferior phrenic veins follow the
course of the inferior phrenic arteries, and terminate, the right in the inferior vena
cava, the left in the left renal vein.
The hepatic veins commence in the substance of the liver, in the capillary ter-
minations of the vena portae ; these branches, gradually uniting, form three large
veins, which converge towards the posterior border of the liver, and open into the
inferior vena cava, 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
lobes open obliquely into the vena cava; that from the middle of the organ and
lobus Spigelii having a straight course. The hepatic veins run singly, and are
in direct contact with the hepatic tissue. They are destitute of valves.
PORTAL SYSTEM OF VEINS.
The portal venous system is composed of four large veins, which collect the
venous blood from the viscera of digestion. The trunk formed by their union,
the vena portae, enters the liver, ramifies throughout its substance, and its branches,
again emerging from that organ as the hepatic veins, terminate in the inferior
vena cava. The branches of this vein are in all cases single, and destitute of
valves.
The veins forming the portal system are the
Inferior mesenteric. Splenic.
Superior mesenteric. Gastric.
The inferior mesenteric vein returns the blood from the rectum, sigmoid flexure,
and descending colon, corresponding with the ramifications of the branches of the
inferior mesenteric artery. Ascending 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 inosculate with those
of the internal iliac, and thus establish a communication between the portal and
the general venous system.
The superior mesenteric vein returns the blood from the small intestines, and
from the caecum and ascending and transverse portions of the colon, correspond-
ing 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 vena portae.
The splenic vein 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 behind the upper border of the pancreas, and terminates
at its greater end by uniting at a right angle with the superior mesenteric to form
the vena portae. 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 gastric is a vein of small size, which accompanies the gastric artery from
left to right along the lesser curvature of the stomach, and terminates in the vena
portae.
The Portal Vein 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 great end of the pancreas. Passing upwards 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
41S
VEINS.
hepatic artery and hepatic duct throughout its substance. Of these two branches
the right is the larger but the shorter of the two. The portal vein is about four
inches in length, and, whilst contained in the lesser omentum, lies behind and
between the hepatic duct and artery, the former being to the right, the latter to
the left. These structures are accompanied by filaments of the hepatic plexus
and numerous lymphatics, surrounded by a quantity of loose areolar tissue, the
Fig. 246.— Portal Vein aud its Branches.
capsule of Glisson, and placed between the layers of the lesser omentum. The
vena portae receives the gastric and cystic veins ; the latter vein sometimes ter-
minates in the right branch of the vena porta?. Within the liver, the portal vein
receives the blood from the branches of the hepatic artery.
CARDIAC— PULMONARY. 479
CARDIAC VEINS.
The veins which return the blood from the substance of the heart are the
Great cardiac vein. Anterior cardiac veins.
Posterior cardiac vein. Venae Thebesii.
The Great Cardiac Vein 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 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 coronary sinus, its aperture being guarded by two
valves. It receives the posterior cardiac vein, and the left cardiac veins from
the left auricle and ventricle, one of which, ascending along the left margin of
the ventricle, is of large size. The branches joining it are provided with
valves.
The Posterior Cardiac Vein commences, by small branches, 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 the veins from the posterior
surface of both ventricles.
The Anterior Cardiac Veins are three or four small branches, 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 Vense Thebesii 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, on the inner surface of the right
auricle.
The Coronary Sinus is that portion of the 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 the great cardiac vein, the posterior cardiac vein,
and an oblique vein from the back part of the left auricle, the remnant of the
obliterated left innominate trunk of the foetus, described by Mr. Marshall. The
coronary sinus terminates in the right auricle, between the inferior vena cava
and the auriculo-ventricular aperture, its orifice being guarded by a semilunar
fold of the lining membrane of the heart, the coronary valve. All the branches
joining this vessel, excepting the oblique vein above mentioned, are provided
with valves.
THE PULMONARY VEINS.
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 pul-
monary 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 parietes of the
bronchial cells, where they are continuous with the ramifications of the pulmonary
artery, and, uniting together, form a single trunk for each lobule. These branches,
successively uniting, form a single trunk for each lobe, three for the right, and two
for the left, lung. The vein of the middle lobe of the right lung unites with that
from the upper lobe, in most cases, forming two trunks on each side, which open
480 VEINS.
separately into the left auricle. Occasionally they remain separate ; there are then
three 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.
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, the left pass in front of the thoracic aorta, with the left pul-
monary artery.
Of the Lymphatics.
The Lymphatics have derived their name from the appearance of the fluid
contained in their interior (lympha, water). They are also called absorbents, from
the property they possess of absorbing certain materials for the replenishing of
the blood, and conveying them into the circulation.
The lymphatic system includes not only the lymphatic vessels and the glands
through which they pass, but also 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 they contain a milk-white fluid, the chyle,
during the process of digestion, and convey it into the blood through the thoracic
duct.
The lymphatics are exceedingly delicate vessels, the coats of which are so
transparent that, the fluid they contain is readily seen through them. They retain
a nearly uniform size, being interrupted at intervals by constrictions, which give
to them a knotted or beaded appearance. These constrictions correspond to the
presence of valves in their interior. Lymphatics are found in nearly every texture
and organ of the body, with the exception of the substance of the brain and
spinal cord, the eyeball, cartilage, tendon, membranes of the ovum, the placenta,
and umbilical cord, the nails, cuticle, and hair. Their existence in the substance
of bone is doubtful.
The lymphatics are arranged into a superficial and deep set. The superficial
lymphatics, on the surface of the body, are placed immediately beneath the integu-
ment, accompanying the superficial veins ; they join the deep lymphatics in certain
situations by perforating the deep fascia. In the interior of the body, they lie in
the submucous areolar tissue, throughout the whole length of the gastro-pulmonary
and genito- urinary tracts ; or in the subserous areolar tissue, beneath the serous
membrane covering the various organs in the cranial, thoracic, and abdominal
cavities. These vessels probably arise in the form of a dense plexiform network
interspersed among the proper elements and bloodvessels of the several tissues;
the vessels composing which, as well as the meshes between them, are much larger
than those of the capillary plexus. From these networks small vessels emerge,
which pass, either to a neighboring gland, or to join some larger lymphatic trunk.
The deep lymphatics, fewer in number, and larger than the superficial, accompany
the deep bloodvessels. Their mode of origin is not known; it is, however,
probably similar to that of the superficial vessels. The lymphatics of any part
or organ exceed, in number, the veins; but in size, they are much smaller.
Their anastomoses also, especially of the large trunks, are more frequent, and are
effected by vessels equal in diameter to those which they connect, the continuous
trunks retaining the same diameter.
The lymphatic vessels, like arteries and veins, are composed of three coats.
The internal is an epithelial and elastic coat ; it is thin, transparent, slightly
elastic, and ruptures sooner than the other coats. It is composed of a layer of
elongated epithelial cells, supported on a simple network of elastic fibres.
The middle coat is composed of smooth muscular and fine elastic fibres disposed
in a transverse direction.
The external or areolo-fibrous coat consists of filaments of areolar tissue,
intermixed with smooth muscular fibres, longitudinally or obliquely disposed. It
forms a protective covering to the other coats, and serves to connect the vessel
with the neighboring structures.
31 481
482 LYMPHATICS.
The lymphatics are supplied by nutrient vessels, which are distributed to
their outer and middle coats ; but no nerves have at present been traced into
them.
The lymphatics are very generally provided with valves, which assist materially
in effecting the circulation of the fluid they contain. They are formed of a thin
layer of fibrous tissue, lined on both surfaces with scaly epithelium. Their form
is semilunar ; they are attached by their convex edge to the sides of the vessel,
the concave edge being free, and directed in the course of the contained current.
Usually, two such valves, of equal size, are found placed opposite one another ;
but occasionally exceptions occur, especially at or near the anastomoses of lymphatic
vessels. Thus one valve may be of very rudimentary size, the other increased in
proportion. In other cases, the semilunar flaps have been found directed trans-
versely across the vessel, instead of obliquely, so as to impede the circulation in
both directions, but not to completely arrest it in either ; or the semilunar flaps,
taking the same direction, have been united on one side, so that they formed, by
their union, a transverse septum, having a partial transverse slit ; and sometimes
the flap was constituted of a circular fold, attached to the entire circumference of
the vessel, and having in its centre a circular or elliptical aperture, the arrange-
ments of the flaps being similar to those composing the ileo-ceecal valve.
The valves in the lymphatic vessels are placed at much shorter intervals than
in the veins. They are most numerous near the lymphatic glands, and they are
found more frequently in the lymphatics of the neck and upper extremity, than in
the lower. The wall of the lymphatics, immediately above the point of attachment
of each segment of a valve, is expanded into a pouch or sinus, which gives to
these vessels, when distended, the knotted or beaded appearance which they present.
Valves are wanting in the vessels composing the plexiform network in which the
lymphatics originate.
There is no satisfactory evidence to prove that any natural communication exists
between the lymphatics of glandular organs and their ducts, or between the
lymphatics and the capillary vessels.
The lymphatic or absorbent glands, named also conglobate glands, are small
solid glandular bodies, situated in the course of the lymphatic and lacteal vessels.
They are found in the neck and on the external parts of the head ; in the upper
extremity, in the axilla and front of the elbow ; in the lower extremity, in the
groin and popliteal space. In the abdomen, they are found in large numbers in
the mesentery, and along the side of the aorta, vena cava, and iliac vessels ; and in
the thorax, in the anterior and posterior mediastina. They are somewhat flattened,
and of a round or oval form. In size, they vary from a hempseed to an almond,
and their color, on section, is of a pinkish-gray tint, excepting the bronchial
glands which in the adult are mottled with black. Each gland has a layer of
cellular tissue investing it, forming a capsule, from which prolongations dip into
its substance forming partitions. The lymphatic and lacteal vessels pass through
these bodies in their passage to the thoracic and lymphatic ducts. A lymphatic
or lacteal, previous to its entering a gland, divides into several small branches, which
are named afferent vessels. As they enter, their external coat becomes continuous
with the capsule of the gland, and the vessels, much thinned, and consisting only
of their internal coat and epithelium, pass into the gland, where, subdividing,
they pursue a tortuous course ; and finally anastomosing form a plexus. The
vessels composing this plexus unite to form two or more efferent vessels, which
on emerging from the gland are again invested with their external coat. Within
the lymphatic vessels, as supposed by Kolliker, Goodsir, and others, or lying
between them, grouped in cells, like the acini of secreting glands, is a large
number of minute dotted corpuscles. They are spheroidal or disk-shaped pellucid
particles, about -g^Vtr of an inch in diameter, having two or three minute dark
particles in their interior. It is probable that they play an important part in the
more complete elaboration of the lymph or chyle traversing the glands. Capillary
vessels are abundantly distributed on the walls of the lymphatics in the glands.
THORACIC DUCT.
483
Thoracic Duct.
The Thoracic Duct (fig. 247) conveys the great mass of the lymph and chyle
into the blood. It is the common trunk of all the lymphatic vessels of the body,
excepting those of the right
Side of the head, neck, and &S- 247.-The Thoracic and Right Lymphatic Ducts.
thorax, and right upper ex-
tremity, the right lung, right
side of the heart, and the
convex surface of the liver.
It varies from eighteen to
twenty inches in length in
the adult, and extends from
the second lumbar vertebra
to the root of the neck. It
commences in the abdomen
by a triangular dilatation, the
receptaculum chyli (reservoir
or cistern of Pecquet), which
is situated upon the front of
the body of the second lumbar
vertebra, to the right side of
and behind the aorta, by the
side of the right crus of the
Diaphragm. It ascends into
the thorax through the aortic
opening in the Diaphragm,
and is placed in the posterior
mediastinum in front of the
vertebral column, lying be-
tween the aorta and vena
azygos. Opposite the fourth
dorsal vertebra it inclines to-
wards the left side and ascends
behind the arch of the aorta,
on the left side of the oeso-
phagus, and behind the first
portion of the left subclavian
artery, to the upper orifice of
the thorax. Opposite the
upper border of the seventh
cervical vertebra it curves
downwards above the sub-
clavian artery, and in front
of the Scalenus muscle, so as
to form an arch ; and ter-
minates near the angle of
junction of the left internal
jugular and subclavian veins.
The thoracic duct, at its com-
mencement, is about equal in
size to the diameter of a goose-
quill, diminishes considerably
in its calibre in the middle
of the thorax, and is again dilated just before its termination. It is generally
flexuous in its course, and constricted at intervals so as to present a varicose
484 LYMPHATICS.
appearance. The thoracic duct not unfrequently divides in the middle of its
course into two branches of unequal size which soon reunite, or into several
branches which form a plexiform interlacement. It occasionally bifurcates, at
its upper part, into two branches, the left one terminating in the usual manner, the
right one opening into the right subclavian vein, in connection with the right
lymphatic duct. The thoracic duct has numerous halves throughout its whole
course, but they are more numerous in the upper than in the lower part ; at its
termination it is provided with a pair of valves, the free borders of which are
turned towards the vein, so as to prevent the regurgitation of venous blood into
the duct.
Branches. The thoracic duct at its commencement receives four or five large
trunks from the abdominal lymphatic glands, and also the trunk of the lacteal
vessels. Within the thorax, it is joined by the lymphatic vessels from the left
half of the wall of the thoracic cavity, the lymphatics from the sternal and
intercostal glands, those of the left lung, left side of the heart, trachea, and oeso-
phagus ; and, just before its termination, receives the lymphatics of the left side
of the head and neck, and 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
layer of epithelium, resting upon some striped lamellae, and an elastic fibrous coat,
the fibres of which run in a longitudinal direction. The middle coat consists
of a layer of connective tissue, beneath which are several laminae of muscular
tissue, the fibres of which are disposed transversely, and intermixed with fine
elastic fibres. The external coat is composed of areolar tissue, with elastic fibres
and isolated fasciculi of muscular fibres.
The Right Lymphatic Duct is a short trunk, about an inch in length, and a
line or a line and a half in diameter, which receives the lymph from the right side
of the head and neck, the right upper extremity, the right side of the thorax, the
right lung and right side of the heart, and from the convex surface of the liver,
and terminates at the angle of union of the right subclavian and right internal
jugular veins. Its orifice is guarded by two semilunar valves, which prevent the
entrance of blood from the veins.
Lymphatics of the Head, Face, and Neck.
The Superficial Lymphatic Glands of the Head (fig. 248) are of small size,
few in number, and confined to its posterior region. They are the occipital, placed
at the back of the head along the attachment of the Occipito-frontalis ; and the
posterior auricular, near the upper end of the Sterno-mastoid. These glands
become considerably enlarged in cutaneous affections and other diseases of the
scalp. In the face, the superficial lymphatic glands are more numerous : they
are the parotid, some of which are superficial and others deeply placed in its
substance ; the zygomatic, situated under the zygoma ; the buccal, on the surface
of the Buccinator muscle ; and the submaxillary, the largest, beneath the body of
the lower jaw.
The superficial lymphatics of the head are divided into an anterior and a
posterior set, which follow the course of the temporal and occipital vessels. The
temporal set accompany the temporal artery in front of the ear, to the parotid
lymphatic glands, from which they proceed to the lymphatic glands of the neck.
The occipital set follow the course of the occipital artery, descend to the occipital
and posterior auricular lymphatic glands, and from thence join the cervical
glands.
The superficial lymphatics of the face are more numerous than those of the
head. They commence over its entire surface, those from the frontal region accom-
panying the frontal vessels; they then pass obliquely across the face, accompanying
the facial vein, pass through the buccal glands on the surface of the Buccinator
muscle, and join the submaxillary lymphatic glands. The latter receive the
OF THE HEAD, FACE, AND NECK.
485
lymphatic vessels from the lips, and are often found enlarged in cases cf malignant
disease of these parts.
The deep lymphatics of the face are derived from the pituitary membrane of the
nose, the mucous membrane of the mouth and pharynx, and the contents of the
temporal aud orbital fossae; they accompany the branches of the internal
maxillary artery, and terminate in the deep parotid and cervical lymphatic
glands.
The deep lymphatics of the cranium consist of two sets, the meningeal and cere-
bral. The meningeal lymphatics accompany the meningeal vessels, escape through
foramina at the base of the skull, and join the deep cervical lymphatic glands.
Fig. 248. — The Superficial Lymphatics and Glands of the Head, Face and Neck.
The cerebral tymphatics are described by Fohmann as being situated between the
arachnoid and pia mater, as well as in the choroid plexuses of the lateral ven.
tricles ; they accompany the trunks of the carotid and vertebral arteries, and pro-
bably pass through foramina at the base of the skull, to terminate in the deep
cervical glands. They have not at present been demonstrated in the dura mater,
or in the substance of the brain.
The Lymphatic Glands of the Neck are divided into two sets, superficial and deep.
The superficial cervical glands are placed in the course of the external jugular
vein, between the Platysma and Sterno-mastoid. They are most numerous at the
root of the neck, in the triangular interval between the clavicle, the Sterno-
486
LYMPHATICS
mastoid, and the Trapezius, where they are continuous with the axillary glands.
A few small glands are also found on the front and sides of the larynx.
The deep cervical glands (fig. 249) are numerous and of large size ; they form
an uninterrupted chain along the sheath of the carotid artery and internal jugular
vein, lying by the side of the pharynx, oesophagus, and trachea, and extending
from the base of the skull to the thorax, where they communicate with the lym-
phatic glands in this cavity.
Fig. 249. — The Deep Lymphatics and Glands of the Neck and Thorax.
The superficial and deep cervical lymphatics are a continuation 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, oesophagus, larynx.,
trachea, and thyroid gland. At the lower part of the neck, after receiving
some lymphatics from the thorax, they unite into a single trunk, which termi-
nates on the left side, in the thoracic duct ; on the right side, in the right lym-
phatic duct.
Lymphatics of the Upper Extremity.
The Lymphatic Glands of the upper extremity (fig. 250) may be subdivided
into two sets, superficial and deep.
OF THE UPPER EXTREMITY.
481
The superficial lymphatic glands are few, and. of small size. There are occa-
sionally two or three in front of the elbow, and one or two above the internal
condyle of the humerus, near the basilic vein.
The deep lymphatic glands are also few in number. In the forearm a few
small ones are occasionally found in the course of the radial and ulnar vessels ;
and in the arm, there is a chain of small glands along the inner side of the brachial
artery.
Fig. 250. — The Superficial Lymphatics and Glands of the Upper Extremity.
The axillary glands are of large size, and usually ten or twelve in number.
A chain of these glands surrounds the axillary vessels, imbedded in a quantity of
loose areolar tissue ; they receive the lymphatic vessels from the arm ; others are
dispersed in the areolar tissue of the axilla : the remainder are arranged in two
series, a small chain running along the lower border of the Pectoralis major, as
far as the mammary gland, receiving the lymphatics from the front of the chest
and mamma ; others are placed along the lower margin of the posterior wall of
488 LYMPHATICS.
the axilla, which receive the lymphatics from the integument of the back. Two
or three subclavian lymphatic glands are placed immediately beneath the clavicle;
it is through these that the axillary and deep cervical glands communicate with
each other. One is figured by Mascagni near the umbilicus. In malignant diseases,
tumors, 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, and arm, the axillary glands are usually found
enlarged.
The superficial lymphatics of the upper extremity arise from the skin of the
hand, and run along the sides of the fingers chiefly on the dorsal surface of the
hand ; they then pass up the forearm, and subdivide into two sets, which take the
course of the subcutaneous veins. Those from the inner border of the hand accom-
pany the ulnar veins along the inner side of the forearm to the bend of the elbow,
where they join with some lymphatics from the outer side of the forearm ; they
then follow the course of the basilic vein, communicate with the glands immediately
above the elbow, and terminate in the axillary glands, joining with the deep
lymphatics. The superficial lymphatics from the outer and back part of the hand
accompany the radial veins to the bend of the elbow, being less numerous than the
preceding. Here the greater number join the basilic group ; the rest ascend with
the cephalic vein on the outer side of the arm, some crossing obliquely the upper
part of the Biceps to terminate in the axillary glands, whilst one or two accompany
the cephalic vein in the cellular interval between the Pectoralis major and Deltoid,
and enter the subclavian lymphatic glands.
The deep lymphatics of the upper extremity accompany the deep bloodvessels.
In the forearm, they consist of three sets, corresponding with the radial, ulnar,
and interosseous arteries ; they pass through the glands occasionally found in the
course of these vessels, and communicate at intervals with the superficial lymphatics.
In their ascent upwards, some of them pass through the glands which lie upon the
brachial artery ; they then enter the axillary and subclavian glands, and at the root
of the neck terminate, on the left side in the thoracic duct, and on the right side
in the right lymphatic duct.
Lymphatics of the Lower Extremity.
The Lymphatic Glands of the lower extremity may be subdivided into two sets,
superficial and deep.
The superficial lymphatic glands are confined to the inguinal region.
The superficial inguinal glands, placed immediately beneath the integument,
are of large size, and vary from eight to ten in number. They are divisible into
two groups ; an upper, disposed irregularly along Poupart's ligament, receiving
the lymphatic vessels from the integument of the scrotum, penis, parietes of the
abdomen, perineum, and gluteal regions ; and an inferior group, which surrounds
the saphenous opening in the fascia lata, a few being sometimes continued along
the saphenous vein to a variable extent. The latter receive the superficial lymphatic
vessels from the lower extremity. These glands frequently become enlarged in
diseases implicating the parts from which their efferent lymphatics originate.
Thus, in malignant or syphilitic affections of the prepuce and penis, the labia
majora in the female, in cancer scroti, in abscess in the perineum, or in any other
disease affecting the integument and superficial structures in these parts, or the
sub-umbilical part of the abdomen or gluteal region, the upper chain of glands is
almost invariably enlarged, the lower chain being implicated in diseases affecting
the lower limb.
The deep lymphatic glands are the anterior tibial, popliteal, deep inguinal,
gluteal, and ischiatic.
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.
OF THE LOWER EXTREMITY.
489
The deep popliteal glands, four or five
in number, are of small size; they sur-
round the popliteal vessels, imbedded in
the cellular tissue and fat of the popliteal
space.
The deep inguinal glands are placed
beneath the deep fascia around the femoral
artery and vein. They are of small size,
and communicate with the superficial
inguinal glands through the saphenous
opening.
The gluteal and ischiatic glands are
placed, the former above, the latter below,
the Pyriformis muscle, resting on their
corresponding vessels as they pass through
the great sacro -sciatic foramen.
The Lymphatics of the lower extremity,
like the veins, may be divided into two
sets, superficial and deep.
The superficial lymphatics are placed
between the integument and superficial
fascia, and are divisible into two groups,
an internal group, which follow the course
of the internal saphenous vein; and an
external group, which accompany the
external saphenous.
The internal group, the largest, com-
mence on the inner side and dorsum of
the foot ; they pass, some in front of, and
some behind, the inner ankle, ascend the
leg with the internal saphenous vein, pass
with it behind the inner condyle of the
femur, and accompany it to the groin,
where they terminate in the group of in-
guinal glands which surround the saphe-
nous opening. Some of the efferent vessels
from these glands pierce the cribriform
fascia and sheath of the femoral vessels,
and terminate in a lymphatic gland
contained in the femoral canal, thus
establishing a communication between
the lymphatics of the lower extremity
and those of the trunk ; others pierce the
fascia lata, and join the deep inguinal
glands.
The external group arise from the outer
side of the foot, ascend in front of the leg,
and, just below the knee, cross the tibia
from without inwards, to join the lym-
phatics on the inner side of the thigh.
Others commence on the outer side of the
foot, pass behind the outer malleolus, and
accompany the external saphenous vein
along the back of the leg, where they
enter the popliteal glands.
The deep lymphatics of the lower ex-
tremity are few in number, and accompany
Fig. 251. — The Superficial Lymphatics and
Glands of the Lower Extremity.
Superficia
490 LYMPHATICS.
the deep bloodvessels. In the leg, they consist of three sets, the anterior tibial,
peroneal, and posterior tibial, which accompany the corresponding vessels, being
two or three in number to each ; they ascend with the bloodvessels, 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, the
vessels pass beneath Poupart's ligament, and communicate with the chain of
glands surrounding the external iliac vessels.
The deep lymphatics of the gluteal and ischiatic regions follow the course of
the bloodvessels, and join the gluteal and ischiatic glands at the great sacro-sciatic
foramen.
Lymphatics of the Pelvis and Abdomen.
The Deep Lymphatic Glands in the Pelvis are, the external iliac, the internal
iliac, and the sacral. Those of the abdomen are the lumbar glands.
The external iliac glands form an uninterrupted chain round the external iliac
vessels, three being placed round the commencement of the vessel just behind the
crural arch. They communicate below with the femoral lymphatics, and above
with the lumbar glands.
The internal iliac glands surround the internal iliac vessels ; they receive the
lymphatics corresponding to the branches of the internal iliac artery, and com-
municate with the lumbar glands.
The sacral glands occupy the sides of the anterior surface of the sacrum, some
being situated in the mesorectal fold. These and the internal iliac glands become
greatly enlarged in malignant disease of the bladder, rectum, or uterus.
The lumbar glands are very numerous ; they are situated on the front of the
lumbar vertebras, surrounding the common iliac vessels, the aorta, and vena cava ;
they receive the lymphatic vessels from the lower extremities and pelvis, as well
as from the testes and some of the abdominal viscera. The efferent vessels from
these glands unite into a few large trunks, which, with the lacteals, form the com-
mencement of the thoracic duct. In some cases of malignant disease, these glands
become enormously enlarged, completely surrounding the aorta and vena cava,
and occasionally greatly contracting the calibre of these vessels. In all cases of
malignant disease of the testis, and in malignant disease of the lower limb, before
any operation is attempted, careful examination of the abdomen should be made,
in order to ascertain if any enlargement exists ; and if any should be detected,
all operative measures are fruitless.
The lymphatics of the pelvis and abdomen may be divided into two sets, superficial
and deep.
The superficial lymphatics of the walls of the abdomen and pelvis follow the course
of the superficial bloodvessels. Those derived from the integument 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 superficial inguinal
glands ; the deep set accompany the deep epigastric vessels, and communicate with
the external iliac glands. The superficial lymphatics from the sides and lumbar part
of the abdominal wall wind round the crest of the ilium, accompanying the super-
ficial circumflex iliac vessels, to join the superior group of the superficial inguinal
glands; the greater number, however, accompany the ilio-lumbar and lumbar
vessels backwards, to join the lumbar glands.
The superficial lymphatics of the gluteal region turn horizontally round the outer
side of the nates, and join the superficial inguinal glands.
The superficial lymphatics of the scrotum and perinseum follow the course of the
external pudic vessels, and terminate in the superficial inguinal glands.
The superficial lymphatics of the penis occupy the sides and dorsum of the organ,
the latter receiving the lymphatics from the skin covering the glans penis; they
all converge to the upper chain of the superficial inguinal glands. The deep
lymphatic vessels of the penis follow the course of the internal pudic vessels, and
join the internal iliac glands.
OF THE PELVIS AND ABDOMEN
491
In the female, the lymphatic vessels of the mucous membrane of the labia,
nymphae, and clitoris, terminate in the upper chain of the inguinal lymphatic
glands.
The deep lymphatics of the pelvis and abdomen take the course of the principal
bloodvessels. Those 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 lumbar lymphatics.
Fig. 252. — The Deep Lymphatic Vessels and Glands of the Abdomen and Pelvis.
Sxttrnal
Ilia* daul*
Clanrti
Sacral G//z>/ch
Internal
\lliae Glands
Deej} Lymphati.es
of PeM3
The efferent vessels from the inguinal glands enter the pelvis beneath Poupart's
ligament, where they lie in close relation with the femoral vein ; they then pass
through the chain of glands surrounding the external iliac vessels, and finally
terminate in the lumbar glands. They receive the deep epigastric, circumflex
iliac, and ilio-lumbar lymphatics.
492 LYMPHATICS.
The lymphatics of the Madder arise from the entire surface of the organ ; the
greater number run beneath the peritoneum on its posterior surface, and, after
passing through the lymphatic glands in this situation, join with the lymphatics
from the prostate and vesicular seminales, and enter the internal iliac glands.
The lymphatics of the rectum are of large size ; after passing through some small
glands that lie upon its outer wall and in the mesorectum, they pass to the sacral
or lumbar glands.
The lymphatics of the uterus consist of two sets, superficial and deep; the
former being placed beneath the peritoneum, the latter in the substance of the
organ. The lymphatics of the cervix uteri, together with those from the vagina,
enter the internal iliac and sacral glands ; those from the body and fundus of the
uterus pass outwards in the broad ligaments, and, being joined by the lymphatics
from the ovaries, broad ligaments, and Fallopian tubes, ascend with the ovarian
vessels to open into the lumbar glands. In the unimpregnated uterus, they are
small ; but during gestation they become very greatly enlarged.
The lymphatics of the testicle consist of two sets, superficial and deep; the
former commence on the surface of the tunica vaginalis, the latter in the epidi-
dymis and body of the testis. They form several large trunks, which ascend with
the spermatic cord, and, accompanying the spermatic vessels into the abdomen,
open into the lumbar glands ; hence the enlargement of these glands in malignant
disease of the testis.
The lymphatics of the kidney arise on the surface, and also in the interior of the
organ; they join at the hilus, and, after receiving the lymphatic vessels from the
ureter and supra-renal capsule, open into the lumbar glands.
The lymphatics of the liver are divisible into two sets, superficial and deep.
The former arise in the sub-peritoneal areolar tissue over the entire surface of the
organ. Those on the convex surface may be divided into four groups : — 1. Those
which pass from behind forwards, consisting of three or four branches, which
ascend in the longitudinal ligament, and unite to form a single trunk, which passes
up between the fibres of the Diaphragm, behind the ensiform cartilage, to enter
the anterior mediastinal glands, and finally ascends to the root of the neck, to
terminate in the right lymphatic duct. 2. Another group, which also incline
from behind forwards, are reflected over the anterior margin of the liver to its
under surface, and from thence pass along the longitudinal fissure to the glands
in the gastro-hepatic omentum. 3. A third group incline outwards to the right
lateral ligament, and, uniting into one or two large trunks, pierce the Diaphragm,
and run along its upper surface to enter the anterior mediastinal glands; or,
instead of entering the thorax, turn inwards across the crus of the Diaphragm,
and open into the commencement of the thoracic duct. 4. The fourth group
incline outwards from the surface of the left lobe of the liver to the left lateral
ligament, pierce the Diaphragm, and, passing forwards, terminate in the glands in
the anterior mediastinum.
The superficial lymphatics on the under surface of the liver are divided into three
sets: — 1. Those on the right side of the gall-bladder enter the lumbar glands. 2.
Those surrounding the gall-bladder form a remarkable plexus, which accompanies
the hepatic vessels, and open into the glands in the gastro-hepatic omentum. 3.
Those on the left of the gall-bladder pass to the oesophageal glands, and to those
placed along the lesser curvature of the stomach.
The deep lymphatics accompany the branches of the portal vein and the hepatic
artery and duct through the substance of the liver ; passing out at the transverse
fissure, they enter the lymphatic glands along the lesser curvature of the stomach
and behind the pancreas, or join with one of the lacteal vessels previous to its
termination in the thoracic duct.
The lymphatic glands of the stomach are of small size ; they are placed along
the lesser and greater curvatures, some within the gastro-splenic omentum, whilst
others surround its cardiac and pyloric orifices.
The lymphatics of the stomach consist of two sets, superficial and deep ; the
OF THE INTESTINES AND THORAX. 493
former originating in the subserous, and the latter in the submucous coat. They
follow the course of the bloodvessels, and may consequently be arranged into
three groups. The first group accompany the coronary vessels along the lesser
curvature, receiving branches from both surfaces of the organ, and pass to the
glands around the pylorus. The second group pass from the great end of the
stomach, accompany the vasa brevia, and enter the splenic lymphatic glands.
The third group run along the greater curvature with the right gastro-epiploic
vessels, and terminate at the root of the mesentery in one of the principal lacteal
vessels.
The lymphatic glands of the spleen occupy the hilus. Its lymphatic vessels 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 through a series of small glands, and, after receiving the lymphatics
from the pancreas, ultimately pass into the thoracic duct.
The Lymphatic System of the Intestines.
The lymphatic glands of the small intestine are placed between the layers of the
mesentery, occupying the meshes formed by the superior mesenteric vessels,
and hence called mesenteric glands. 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. These
glands are most numerous, and largest, superiorly near the duodenum, and inferiorly
opposite the termination of the ileum in the colon. The latter group become
greatly enlarged and infiltrated with deposit in cases of fever accompanied with
ulceration of the intestines.
The lymphatic glands of the large intestine are much less numerous than the
mesenteric glands ; they are situated along the vascular arches formed by the
arteries previous to their distribution, and even sometimes upon the intestine itself.
They are fewest in number along the transverse colon, where they form an unin-
terrupted chain with the mesenteric glands.
The lymphatics of the small intestine are called lacteals, from the milk-white
fluid they usually contain ; they consist of two sets, superficial and deep ; the
former lie beneath the peritoneal coat, taking a longitudinal course along the
outer side of the intestine ; the latter occupy the submucous tissue, and course
transversely round the intestine, accompanied by the branches of the mesenteric
vessels: they pass between the layers of the mesentery, enter the mesenteric
glands, and finally unite to form two or three large trunks, which terminate in
the thoracic duct.
The lymphatics of the large intestine consist of two sets: those of the caecum,
ascending and transverse colon, which, after passing through their proper glands,
enter the mesenteric glands ; and those of the descending colon and rectum, which
pass to the lumbar glands.
The Lymphatics of the Thorax.
The deep lymphatic glands of the thorax are the intercostal, internal mammary,
anterior mediastinal, and posterior mediastinal.
The intercostal glands are small, irregular in number, and situated on each side
of the spine, near the costo-vertebral articulations, some being placed between the
two planes of intercostal muscles.
The internal mammary glands are placed at the anterior extremity of each
intercostal space, by the side of the internal mammary vessels.
The anterior mediastinal glands are placed in the loose areolar tissue of the
anterior mediastinum, some lying upon the Diaphragm in front of the pericardium,
and others round the great vessels at the base of the heart.
The posterior mediastinal glands are situated in the areolar tissue in the posterior
mediastinum, forming a continuous chain by the side of the aorta and oesophagus;
494 LYMPHATICS.
they communicate on each side with the intercostal, below with the lumbar glands,
and above with the deep cervical.
The superficial lymphatics of the front of the thorax run across the great Pectoral
muscle, and those on the back part of this cavity lie upon the Trapezius and
Latissimus dorsi; they all converge to the axillary glands. The lymphatics from
the mamma run along the lower border of the Pectoralis major, through a chain
of small lymphatic glands, and communicate with the axillary glands.
The deep lymphatics of the thorax are the intercostal, internal mammary, and
diaphragmatic.
The intercostal lymphatics follow the course of the intercostal vessels, receiving
lymphatics from the Intercostal muscles and pleura ; they pass backwards to the
spine, and unite with lymphatics from the back part of the" thorax -and spinal canal.
After traversing the intercostal glands, they incline down the spine, and terminate •
in the thoracic duct.
The internal mammary lymphatics follow the course of the internal mammary
vessels ; they commence in the muscles of the abdomen above the umbilicus,
communicating with the epigastric lymphatics, ascend between the fibres of the
Diaphragm at its attachment to the ensiform appendix, and in their course behind
the costal cartilages are joined by the intercostal lymphatics, terminating on the
right side in the right lymphatic duct, on the left side in the thoracic duct.
The lymphatics of the Diaphragm follow the course of their corresponding
vessels, and terminate, some in front in the anterior mediastinal and internal
mammary glands, some behind in the intercostal and hepatic lymphatics.
The bronchial glands are situated round the bifurcation of the trachea and
roots of the lungs. They are ten or twelve in number, the largest being placed
opposite the bifurcation of the trachea, the smallest round the bronchi and their
primary divisions for some little distance within the substance of the lungs. In
infancy, they present the same appearance as lymphatic glands in other situations;
in the adult they assume a brownish tinge, and in old age a deep black color.
Occasionally they become sufficiently enlarged to compress and narrow the canal
of the bronchi ; and they are often the seat of tubercle or deposits of phosphate
of lime.
The lymphatics of the lung consist of 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 bloodvessels, and run along the
bronchi : they both terminate at the root of the lungs in the bronchial glands.
The efferent vessels from these glands, two or three in number, ascend upon the
trachea to the root of the neck, traverse the tracheal and oesophageal glands,
and terminate on the left side in the thoracic duct, and on the right side in the
right lymphatic duct.
The cardiac lymphatics consist of two sets, superficial and deep ; the former
arise in the subserous areolar tissue of the surface, and the latter beneath the
internal lining membrane of the heart ; they follow the course of the coronary
vessels. Those of the right side unite into a trunk at the root of the aorta, which,
ascending across the arch of that vessel, passes backwards to the trachea, upon
which it ascends, to terminate at the root of the neck in the right lymphatic duct;
those of the left side unite into a single vessel at the base of the heart, which
passing along the pulmonary artery, and traversing some glands at the root of the
aorta, ascends on the trachea to terminate in the thoracic duct.
The thymic lymphatics arise from the spinal surface of the thymus gland, and
terminate on each side in the internal jugular veins.
The thyroid lymphatics arise from either lateral lobe of the thyroid gland ; they
converge to form a short trunk, which terminates on the right side in the right
lymphatic duct, on the left side in the thoracic duct.
The lymphatics of the oesophagus form a plexus round that tube, traverse the
glands in the posterior mediastinum, and, after communicating with the pulmonary
lymphatic vessels near the roots of the lungs, terminate in the thoracic duct.
Nervous System.
The Nervous System consists of a series of connected central organs, called
collectively, the cerebrospinal centre or axis, of the ganglia, and of the nerves.
The cerebrospinal portion of the nervous system includes the brain and spinal
cord, with the nerves connected with them, and the ganglia seated upon these
nerves. It was distinguished, by Bichat, as the nervous system of animal life.
It includes those nervous organs in and through which the several functions of
the mind are more immediately connected ; the nerves of the senses, and those
relating to volition and common sensation, are connected with it, as well as those
concerned in many nervous actions, with which the mind has no connection.
The ganglionic or sympathetic system consists of a double chain of ganglia
connected by nervous cords, situate along the spinal column; and from which
nerves with ganglia developed upon them proceed to the viscera in the thoracic,
abdominal and pelvic cavities. It was distinguished, by Bichat, as the nervous
system of organic life. This system is less immediately connected with the mind,
appearing to be more closely concerned than the cerebro-spinal system with the
processes of organic life.
The several organs of the nervous system are composed of two different
substances, which differ from each other in density, color, in their minute struc-
ture, and in their chemical composition. They are called the vesicular nervous
matter and the fibrous nervous matter. The former is often called the gray or
cineritious substance ; and the latter, the white or medullary.
The fibrous nervous matter is most extensively diffused throughout the body.
It forms a large portion of the nervous centres, either alone, or mixed with
vesicular matter ; and is the principal constituent of the nerves which connect
them with the various tissues and organs.
The vesicular nervous matter is usually known by its soft consistence, and dark
reddish-gray color ; it is generally collected into masses intermingled with the
fibrous structure, in various parts of the brain and spinal cord, and in the several
ganglia.
Chemical Composition. The following analysis by Lassaighe represents the
relative proportion of the different constituents composing the gray and white
matter of the brain : —
Gray.
White
Water ....
. 85.2
. 73.0
Albuminous matter .
. 7.5
. 9.9
Colorless fat
. 1.0
. 13.9
Red fat ... .
. 3.7
0.9
Osmazome and lactates
. 1.4
1.0
Phosphates
. 1.2
1.3
100.0 100.0
It appears from this analysis that the cerebral substance consists of albumen,
dissolved in water, combined with fatty matters and salts. The fatty matters,
according to Fremy, consist of cerebric acid, which is most abundant, cholesterin,
oleophosphoric acid, and olein, margarin, and traces of their acids. The same
analyst states, that the fat contained in the brain is confined almost exclusively to
the white substance, and that its color becomes lost when the fatty matters are
removed. According to Vauquelin, the cord contains a larger proportion of fat
495
496 NERVOUS SYSTEM.
than tlie brain ; and, according to L'Heritier, the nerves contain more albumen
and more soft fat than the brain.
Microscopic Structure. The fibrous nervous matter consists of two different
kinds of nerve fibres, which are distinguished as the tubular fibre and the gela-
tinous fibre. In most nerves these two kinds are intermingled; the tubular
fibres being more numerous in the nerves of the cerebro-spinal system, the gela-
tinous predominating in the nerves of the sympathetic system. •
The tubular fibres appear to consist of tubules of simple membrane, homogeneous
in structure, and analogous to the sarcolemma of striped muscle. Within is the
proper nerve substance, composed apparently of two different materials ; the central
part, which occupies the axis of the nerve tube, is a transparent material, termed
the axis cylinder ; while the outer portion, which forms a tube within the tubular
membrane, inclosing the axis-cylinder, is usually opaque and dimly granular, as
if from a kind of coagulation, and is generally known as the white substance
of Schwann. The peculiar white appearance of the cerebro-spinal nerves is
principally due to the large amount of the white substance of Schwann which they
contain. It is probable that the essential element of the nerve tube is the axis
cylinder, the tubular membrane and white substance of Schwann affording me-
chanical protection to this substance, insulating it from the constituent parts of
the neighboring fibres.
In a perfectly fresh state, the nerve tubes present the appearance of simple
membranous tubes, perfectly cylindrical, and containing a transparent and ap-
parently homogeneous material ; but shortly after death, when pressed or separated
by coarse manipulation, they undergo changes which render it probable that their
contents are composed of the two materials above mentioned, for the fine outline
of the previously cylindrical tube is exchanged for a dark double contour, the
outer line being formed by the tubular sheath, the inner by the white substance of
Schwann, at the same time the granular material collects into small masses which
distend the tubular membrane at irregular intervals, while the intermediate spaces
collapse, giving the fibres a varicose or beaded appearance. In the brain, spinal
cord, and nerves of special sense, the tubes are very apt to exhibit this change,
owing to extreme thinness of the tubular membrane and to a diminished con-
sistence of the contained nervous matter. The contents of the nerve tubes are
extremely soft, for when subjected to slight pressure they readily pass from one
part of the canal to another, and often cause a bulging at the side of the tube.
The contents, also, readily escape on pressure from the extremities of the tube,
assuming the appearance and form of globules, consisting of a transparent central
part, surrounded by a layer of the white substance of Schwann, marked by its
double contour.
The nerve fibres vary in size ; they are largest within the trunk and branches
of the nerves, measuring from tj^Vtt to 35VTT of an inch. They become gradually
smaller as they approach the brain and spinal cord, and usually also in the tissues
in which they are distributed. In the gray matter of the brain and spinal cord,
they seldom measure more than TTj^t to y^^u of an inch.
The gelatinous fibres constitute the main part of the trunk and branches
of the sympathetic nerve, and are intermingled in various proportions in the
cerebro-spinal nerves. When collected together in great numbers, they exhibit
a yellowish-gray color. They are flattened, soft, and homogeneous in appearance,
containing nuclei, of a round or oval form, arranged at nearly equal distances,
and frequently presenting nucleoli. They vary in diameter, from ^^ to -^^
of an inch, and resemble much the fibres of unstriped muscle. They differ from
the tubular fibres in their smaller size, being only one-half or one-third their size,
in the absence of the double contour, their apparently uniform structure, and their
yellowish-gray color. It appears probable that these nerves are composed ex-
clusively of the substance which corresponds with the axis cylinder of the tubular
nerves, and differs from them in not possessing the tubular membrane, and white
substance of Schwann.
GENERAL ANATOMY. 491
The vesicular nervous substance is distinguished by its dark reddish-gray
color, and soft consistence. It is found in the brain, spinal cord, and various
ganglia, intermingled with the fibrous nervous substance, but is never found in the
nerves. It is composed, as its name implies, of vesicles or corpuscles, commonly
called nerve or ganglion corpuscles, containing nuclei and nucleoli ; the vesicles
being imbedded either in a finely granular substance, as in the brain, or in a
capsule of nucleated cells, as in the ganglia. Each vesicle consists of an exceed-
ingly delicate membranous wall, inclosing a finely granular material, part of
which is occasionally of a coarser kind, and of a reddish or yellowish-brown
color. The nucleus is vesicular, much smaller than the vesicle, and adherent t< >
some part of its interior. The nucleolus, which is inclosed within the nucleus, is
vesicular in form, of minute size, and peculiarly clear and brilliant. The nerve
corpuscles vary in shape and size; some are small, spherical, or ovoidal, with an
uninterrupted outline ; these forms being most numerous in the ganglia of the
sympathetic. Others, called caudate or stellate nerve corpuscles, are characterized
by their larger size, and from having one or more tail-like processes issuing from
them, which occasionally divide and subdivide into numerous branches. These
processes are very delicate, apparently tubular, and contain a similar granular
material to that found within the corpuscle. Some of the processes terminate
in fine transparent fibres, which become lost among the other elements of the
nervous tissue; others may be traced until, after losing their granular appearance,
they become continuous with an ordinary nerve fibre.
The Ganglia may be regarded as separate and independent nervous centres, of
smaller size and less complex structure than the brain, connected with each other,
with the cerebro-spinal axis, and with the nerves in various situations. They are
found on the posterior root of each of the spinal nerves ; on the posterior or
sensory root of the fifth cranial nerve; on the facial nerve; on the glosso-
pharyngeal and pneumogastric nerves ; in a connected series along each side of
the vertebral column, forming the trunk of the sympathetic ; on the branches of
that nerve in the head, neck, thorax, and abdomen ; or at the point of junction
of branches of that nerve with the cerebro-spinal nerves. On section, they an;
seen to consist of a reddish-gray substance, traversed by numerous white nerve
fibres : they vary considerably in form and size, the largest being those found in
the cavity of the abdomen; the smallest, the microscopic ganglia, which 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 and continuous with the neurilemma
of the nerves. It sends numerous processes into the interior of the ganglia,
which support the bloodvessels supplying its substance.
In structure, all ganglia are essentially similar, consisting of the same
structural elements as the other nervous centres, viz., a collection of vesicular
nervous matter, traversed by tubular and gelatinous nerve fibres. The vesicular
nervous matter consists of nerve cells or ganglion -globules,, most of which appear
free, and of a round or oval form, being more especially seated near the
surface of the ganglion ; others have caudate processes, and give origin to nerve
fibres. In the ganglia, the nerve cells are usually inclosed in a capsule of
granular corpuscles and fibres. The tubular nerve fibres run through the
ganglion, some being collected into bundles ; others, separating from each other,
take a circuitous course among the nerve cells before leaving the ganglia.
The Nerves are round or flattened cords, communicating, on the one hand, with
the cerebro-spinal centre or the ganglia, and, by the other, distributed to the
various textures of the body, forming the medium of communication between
the two.
The nerves are subdivided into two great classes, the cerebro-spinal, which
proceed from the cerebro-spinal axis, and the sympathetic or ganglionic nerves,
which proceed from the ganglia of the sympathetic ; the cerebro-spinal are the
nerves of animal life, being distributed to the organs of the senses, the skin, and
32
498 NERVOUS SYSTEM.
to the active organs of locomotion, the muscles. The sympathetic or ganglionic
nerves are distributed chiefly to the viscera and bloodvessels, and are termed the
nerves of organic life.
The Cerebrospinal nerves consist of numerous nerve fibres, collected together and
inclosed in a membranous sheath. A small bundle of primitive fibres, inclosed
in a tubular sheath, is called a funiculus: if the nerve is of small size, it may
consist only of a single funiculus, but, if large, the funiculi are collected together
into larger bundles or fasciculi; and are bound together in a common membranous
investment, termed the sheath. In structure, the common sheath investing the
whole nerve, as well as the septa given off from it, which separate the fasciculi,
consist of areolar tissue, composed of white and yellow elastic fibres, the latter
existing in greatest abundance. The tubular sheath of the funiculi, the neurilemma,
consists of a fine, smooth, transparent membrane, which may be easity separated,
in the form of a tube, from the fibres it incloses; in structure, it is, for the
most part, a simple and homogeneous transparent film, occasionally composed of
numerous minute reticular fibres.
The cerebro-spinal nerves consist almost exclusively of the tubular nerve fibres,
the gelatinous fibres existing in very small proportion.
The bloodvessels supplying a nerve terminate in a minute capillary plexus,
the vessels composing which run, for the most part, parallel with the funiculi ;
they are connected together by short transverse vessels, forming narrow oblong
meshes, similar to the capillary system of muscle.
The nerve fibres, as far as is at present known, do not coalesce, but pursue an
uninterrupted course from the centre to the periphery. In dissecting a nerve,
however, into its component funiculi, it may be seen that they do not pursue a
perfectly insulated course, but occasionally join at a very acute angle with other
funiculi proceeding in the same direction ; from these, again, branches are given
off, which join again in like manner with other funiculi. It must be remembered,
however, that in these communications the nerve fibres do not coalesce, but merely
pass into the sheath of the adjacent, nerve, become intermixed with the nerve
fibres, and again pass on to become blended with the nerve fibres in some adjoining
fasciculus.
Nerves, in their course, subdivide into branches, and these frequently commu-
nicate with branches of a neighboring nerve. In the subdivision of a nerve, the
filaments of which it is composed are continued from the trunk into the branches,
and at their junction with the branches of neighboring nerves the filaments pass
to become intermixed with those of the other nerve in their further progress ; in
no instance, however, do the separate nerve fibres inosculate.
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 nervous trunks which form it. In the
formation also of the smaller plexuses at the periphery of the body, there is a free
interchange of the fasciculi and primitive fibrils. In each case, however, the
individual filaments remain separate and distinct, and do not inosculate with each
other.
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 each of them had proceeded to be distributed without such connection with
other nerves. Consequently, the parts supplied by these nerves have more ex-
tended relations with the nervous centres ; by this means, also, groups of muscles
may be associated for combined action.
The termination of nerve fibres signifies their mode of distribution and con-
GENERAL ANATOMY. 499
nection in the nerve centres, and in the different organs and tissues they supply ;
the former are called their central, the latter their peripheral terminations.
As to the mode in which the nerve fibres are disposed in the nervous centres, it
is probable that many originate from nerve corpuscles, in the manner before men-
tioned; others probably form simple loops. As to the more exact mode of
connection of the nerve fibres with the nerve corpuscles, it appears that more
commonly as the fibre approaches the vesicle, the white substance of Schwann
gradually disappears, and the tubular membrane expands, so as to envelope the
corpuscle ; the sheath, contracting at the opposite side of the corpuscle, is again
continuous with the tubular sheath of the nerve fibre, a prolongation from the
granular substance of the corpuscle extending for some distance along each, part
of the nerve tube, and taking the place of the usual elements of the nerve fibre.
"Whether this relation of nerve fibres to ganglion-corpuscles is common to all
kinds of nerve fibre's, has yet to be determined.
In the peripheral distribution of the nerves, small bundles of nerve fibres com-
monly form delicate plexuses ; these, dividing, give off the primitive fibres, which
are disposed of in various ways in different tissues. — 1. Occasionally the elemen-
tary fibres are disposed in hops, as has been found in the internal ear, in the
papiike of the tongue and of the skin, in the tooth pulp, and in striped muscular
tissue ; each fibre, after issuing from a branch in a terminal plexus, runs over or
through the substance of the tissue, and, turning back, joins the same or a neigh-
boring branch, in which it probably passes back to a nervous centre. 2. Some-
times each ultimate nerve fibre divides into several branches, which spread out in
the substance of the tissue, as is seen in the retina, in the muscular tissue of the
frog and lower vertebrata. 3. Sometimes the ultimate nerve fibres form minute
plexuses, as in certain serous membranes, viz., the peritoneum, and in the pia mater
of the brain and cord. 4. Not uncommonly the nerve fibres terminate by free
ends, as is seen in the Pacinian corpuscles, and in some of the papiike of the skin.
5. Occasionally, the nerve fibres are brought into direct connection with nerve-
corpuscles, as in the retina and in the lamina spiralis of the internal ear.
Some nerve fibres have no peripheral termination. Gerber has shown, that
nerve fibres occasionally form loops, by their j unction with a neighboring fibre in
the same fasciculus, and return to the cerebro-spinal centre without having any
peripheral termination. These he considers to be sentient nerves, appropriated
exclusively to the nerve itself, the nervi nervorum, upon which the sensibility of
the nerve depends, and quite exclusive of the sensation produced by an impression
made at the peripheral end of the nerve. These fibres bear some analogy to those
met with in the back part of the optic commissure, where a set of fibres passes
from one optic tract across the commissure to the opposite tract, having no com-
munication with the optic nerve ; also in the communications formed between the
cervical nerves and spinal accessory and descendens noni, the nerve fibres forming
an arch connected by each extremity with the cerebro-spinal centre, and having
no peripheral termination.
Again, some nerve fibres would appear to have no central connection with the
cerebro-spinal centre, as those forming the most anterior part of the optic con>
missure. These inter-retinal fibres, as they are called, commence in the retina,
pass along the optic nerve, and across the commissure to the optic nerve and
retina of the opposite side.
The point of connection of a nerve with the brain or spinal cord is called, for
convenience of description, its origin or root. If the fasciculi of which the nerve
is composed should all arise at or near one point, or along one tract, the root is
called single. If, on the contrary, the fasciculi divide into two separate bundles,
which are connected at two different points with any part of the cerebro-spinal
centre, such nerve is said to have a double origin, or to arise by two roots, each of
which may have a separate function, as in the spinal nerves. The point where
the separate fasciculi of a nerve are connected to the surface of the cerebro-spinai
500 NERVOUS SYSTEM.
centre, is called the apparent origin of a nerve ; the term, real or deep origin, being
given to that part of the centre from which a nerve actually springs.
The Sympjathetic nerve consists of tubular and gelatinous fibres, intermixed
with a varying proportion of filamentous areolar tissue, and inclosed in a sheath
formed of fibro-areolar tissue. The tubular fibres are, for the most part, smaller
than those composing the cerebro-spinal nerves; their double contour is less
distinct, and, according to Eemak, they present nuclei similar to those found in
the gelatinous nerve fibres. Those branches of the sympathetic which present a
well-marked gray color are composed more especially of gelatinous nerve fibres,
intermixed with few tubular fibres ; whilst those of a white color contain more
of the tubular fibres, and few gelatinous. 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 nerve fibres both of the cerebro-spinal and sympathetic system convey
impressions of a twofold kind. The sensitive nerves, called also centripetal or
afferent nerves, transmit impressions made upon their peripheral extremities to the
nervous centres, and in this way the mind, through the medium of the brain,
becomes conscious of external objects. The motor nerves, called also centrifugal
or efferent nerves, transmit impressions from the nervous centres to the parts to
which the nerves are distributed, these impressions either exciting muscular con-
tractions, or influencing the processes of nutrition, growth, and secretion.
The Cerebro-spinal Centre consists of two parts, the spinal cord and the ence-
phalon : the latter may be subdivided into the cerebrum, the cerebellum, the pons
Varolii, and the medulla oblongata.
THE' SPINAL COED AND ITS MEMBRANES.
Dissection. To dissect the cord and its membranes, it will be necessary to lay open the whole
length of the spinal 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 hitter
must be sawn 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 haviDg been dis-
placed, by means of a chisel, and the separate fragments removed, the dura mater will be
exposed, covered by a plexus of veins and a quantity of loose areolar tissue, often infiltrated
with a serous fluid. The arches of the upper vertebrae are best divided by means of a strong
pair of forceps.
Membeanes of the Cord.
The membranes which envelop the spinal cord are three in number. The
most external is the dura mater, a strong fibrous membrane, which forms a loose
sheath around the cord. The most internal is the pia mater, a cellulo- vascular
membrane, which closely invests the entire surface of the cord. Between the
two, is the arachnoid membrane, an intermediate serous sac, which envelopes the
cord, and is then reflected on the inner surface of the dura mater.
The Dura Mater of the cord, continuous with that which invests the brain,
is a loose sheath which surrounds it, being separated from the bony walls of the
spinal canal by a quantity of loose areolar adipose tissue, and a plexus of veins.
It is attached to the circumference of the foramen magnum, and to the posterior
common ligament, throughout the whole length of the spinal canal, by fibrous
tissue ; and extends, below, as far as the top of the sacrum ; but, beyond this
point, it is impervious, being continued, in the form of a slender cord, to the back
of the coccyx, where it blends with the periosteum. This sheath is much larger
tnan is necessary for its contents, and its size is greater in the cervical and lumbar
regions, than in the dorsal. Its inner surface is smooth, and covered by a layer of
polygonal cells ; and on each side may be seen the double openings which trans-
mit the two roots of the corresponding spinal nerve, the fibrous layer of the dura
/J~U*
C^<K^ »*<
MEMBRANES OF THE CORD.
501
l'ii
253.— The Spinal Cord and
its Membranes.
mater being continued in the form, of a tubular prolongation on them as they issue
from these apertures. These prolongations of the dura mater are short in the
upper part of the spine, but become gradually longer below, forming a number
of tubes of fibrous membrane, which inclose the sacral nerves, and are contained
in the spinal canal.
The chief peculiarities of the dura mater of the cord, as compared with that
investing the brain, are the following : —
The dara mater of the cord is not adherent to the
bones of the spinal canal, which have an independent
periosteum.
It does not send partitions into the fissures of the
cord, as in the brain.
Its fibrous laminse do not separate, to form venous
sinuses, as in the brain.
Structure. The dura mater consists of white fibrous
tissue, arranged in bands which intersect one another.
It is sparingly supplied with vessels ; and no nerves
have as yet been traced into it.
The Arachnoid is exposed by slitting up the dura
mater, and reflecting this membrane on either side
(fig. 253). It is a thin, delicate, serous membrane,
which invests the outer surface of the cord, and is
then reflected upon the inner surface of the dura
mater, to which it is intimately adherent. That
portion which surrounds the cord is called the vis-
ceral layer of the arachnoid; and that which lines
the inner surface of the dura mater, the parietal
layer;1 the interval between the two is called the
cavity of the arachnoid. The visceral layer forms
a loose sheath around the cord, so as to leave a con-
siderable interval between the two which is called
the sub-arachnoidean space. This space is largest
at the lower part of the spinal canal, and incloses
the mass of nerves which fbrm the cauda equina. It
contains an abundant serous secretion, the cerebro-spinal fluid, and usually com-
municates with the general ventricular cavity of the brain, by means of an opening
in the fibrous layer of the inferior boundary of the fourth ventricle. This
secretion is sufficient in amount to ex-
pand the arachnoid membrane, so as to
completely fill up the whole of the space
included in the dura mater. The sub-
arachnoidean space is crossed, at the back
part of the cord, by numerous fibrous
bands, which stretch from the arachnoid
to the pia mater, especially in the cervi-
cal region, and is partially subdivided
by a longitudinal membranous partition,
which serves to connect the arachnoid
with the pia mater, opposite the posterior
median fissure. This partition is incom-
plete, and cribriform in structure, consisting of bundles of white fibrous tissue,
interlacing with each other. The visceral layer of the arachnoid surrounds the
spinal nerves where they arise from the cord, and in ploses them in a tubular
Fig.
254. — Transverse Section of the Spinal
Cord and its Membranes.
1 Kcilliker denies that the inner surface of the dura mater is covered by an outer layer of the
arachnoid, and states, that nothing is found here except an epithelial layer, no trace of a special
membrane existing.
502 NERYOTTS SYSTEM.
sheath as far as their point of exit from the dura mater, where it becomes con-
tinuous with the parietal layer.
The arachnoid is destitute of vessels. No nerves have as yet been traced into
this membrane.
The Pia Mater of the cord is exposed on the removal of the arachnoid (fig. 253).
It is less vascular in structure than the pia mater of the brain, with which it is
continuous, being thicker, more dense in structure, and composed of fibrous tissue,
arranged in longitudinal bundles. It covers the entire surface of the cord, to
which it is very intimately adherent, forming its neurilemma, and sends a process
downwards into its anterior fissure, and another, extremely delicate, into the
posterior fissure. 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 anterior 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 mater becomes contracted,
and is continued down as a long, slender filament {filum terminale), which
descends through the centre of the mass of nerves forming the cauda equina, and
is blended with the impervious sheath of dura mater, on a level with the top of
the sacral canal. It assists in maintaining the cord in its position during the
movements of the trunk, and is, from this circumstance, called the central
ligament of the spinal cord. It contains a little nervous substance, which may
be traced for some distance into its upper part, and is accompanied by a small
artery and vein.
Structure. The pia mater of the cord, though less vascular than that which
invests the brain, contains a network of delicate vessels in its substance. It is
also supplied with nerves, which are derived from the sympathetic, and from the
posterior roots of the spinal nerves. At the upper part of the cord, the pia
mater presents a grayish, mottled tint, which is owing to yellowish or brown
pigment cells being scattered within its tissue.
The Liyamentum Denticulatum (fig. 253) is a narrow, fibrous band, situated on
each side of the spinal cord, throughout its entire length, and separating the
anterior from the posterior roots of the spinal nerves, having received its name
from the serrated appearance which it presents. Its inner border is continuous
with the pia mater, 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 mater, serving to unite together the two layers of the arachnoid membrane.
These serrations are about twenty in number, on each side, the first being attached
to the dura mater, opposite the margin of the foramen magnum, between the
vertebral artery and the hypoglossal nerve; and the last corresponds to nearly the
lower end of the cord. Its use is to support the cord in the fluid by which it is
surrounded.
The Spinal Cord.
The spinal cord {medulla spinalis) is the cylindrical elongated part of the cerebro-
spinal axis, which is contained in the spinal canal. Its length is usually about
sixteen or seventeen inches, and its weight, when divested of its membranes and
nerves, about one ounce and a half, its proportion to the encephalon being about
1 to 33. It does not nearly fill the canal in which it is contained, its investing
membranes being separated from the surrounding walls by areolar tissue and
a plexus of veins. It occupies, in the adult, the upper two-thirds of the spinal
canal, extending from the foramen magnum to the lower border of the body of
the first lumbar vertebra, where it terminates in a slender filament of gray
substance, the filum terminale, which lies concealed among the leash of nerves
forming the cauda equina. In the foetus, before the third month, it extends to the
bottom of the sacral canal; but, after this period, it gradually recedes from
below, as the growth of the bones composing the canal is more rapid in proportion
SPINAL COED.
503
Fi|T. 255.— Spinal Cord, Side
View. Plan of the Fissures
and Columns.
Posterior
Lateral Fissure
than the cord ; so that, in the child at birth, it extends as far as the third lumbar
vertebra. Its position varies also according to the degree of curvature of the
spinal column, being raised somewhat in flexion of the spine. On examining
its surface it presents a difference in its diameter in different parts, being marked
by two enlargements, an upper or cervical, and a lower or lumbar. The cervical
enlargement, which is the larger, extends from the third cervical to the first dorsal
vertebra : its greatest diameter is in the transverse direction, and it corresponds
with the origin of the nerves which supply the upper extremities. The lower
or lumbar enlargement is situated opposite the last dorsal vertebra, its greatest
diameter being from before backwards. It corresponds with the origin of the
nerves which supply the lower extremities. In form, the spinal cord is a flattened
cylinder. Its anterior surface presents, along the middle line, a longitudinal
fissure, the anterior median fissure ; and, on its posterior surface, another fissure
exists, which also extends along the entire length of the cord, the posterior median
fissure. These fissures serve to divide the cord into two symmetrical halves,
which are united in the middle line, throughout their entire length, by a transverse
band of nervous substance, the commissure.
The Anterior median fissure is wider, but of less
depth, than the posterior, extending into the cord for
about one-third of its thickness, and is deepest at
the lower part of the cord. It contains a prolonga-
tion from the pia mater ; and its floor is formed by
the anterior white commissure, which is perforated by
numerous bloodvessels, which pass to the centre of
the cord.
The Posterior median fissure is much more deli-
cate than the anterior, and most distinct at the upper
and lower parts of the cord. It extends into the
cord to about one-half of its depth. It contains a
very slender process of the pia mater and numerous
bloodvessels, and its floor is formed by a thin layer
of white substance, the posterior white commissure.
Some anatomists state, that the bottom of this fissure
corresponds to the gray matter, except in the cervical region, and at a point
corresponding to the enlargement in the lumbar region.
Lateral Fissures. On either side of the anterior median fissure, a linear series
of foramina may be observed, indicating the points where the anterior roots of
the spinal nerves emerge from the cord. This is called, by some anatomists, the
anterior lateral fissure of the cord, although no actual fissure exists in this
situation. On either side of the posterior median fissure, along the line of
attachment of the posterior roots of the nerves, a delicate fissure may be seen,
leading down to the gray matter which approaches the surface in this situation :
this is called the posterior lateral fissure of the spinal cord. On the posterior
surface of the spinal cord, on either side of the posterior median fissure, is a slight
longitudinal furrow, marking off two slender tracts, the posterior median columns.
These are most distinct in the cervical region, but are stated by Foville to exist
throughout the whole length of the cord.
Columns of the Cord. The fissures divide each half of the spinal cord into
four columns, an anterior column, a lateral column, a posterior column and a
posterior median column.
The anterior column includes all the portion of the cord between the anterior
median fissure and the anterior lateral fissure, from which the anterior roots of
the nerves arise. It is continuous with the anterior pyramid of the medulla
oblongata.
The lateral column, the largest segment of the cord, includes all the portion
between the anterior and posterior lateral fissures. It is continuous with the
lateral column of the medulla. By some anatomists, the anterior and lateral
504 NERVOUS SYSTEM.
columns are included together, under the name of the antero-lateral column,
which forms rather more than two-thirds of the entire circumference of the
cord.
The posterior column is situated between the posterior median and posterior
lateral fissures. It is continuous with the restiform body of the medulla.
The posterior median column is that narrow segment of the cord which is seen
on each side of the posterior median fissure, usually included with the preceding,
as the posterior column.
Structure of the Cord. If a transverse section of the spinal cord be made, it
will be seen to consist of white and gray nervous substance. The white matter
is situated externally, and constitutes its chief portion. The gray substance
occupies its centre, and is so arranged as to present on the surface of the section
two crescentic masses placed one in each lateral half of the cord, united together
by a transverse band of gray matter, the gray commissure. Each crescentic mass
has an anterior and posterior horn. The posterior horn is long and narrow, and
approaches the surface at the posterior lateral fissure, near which it presents a
slight enlargement. The anterior horn is short and thick, and does not quite
reach the surface, but extends towards the point of attachment of the anterior
roots of the nerves. Its margin presents a dentate or stellate appearance. Owing
to this peculiar arrangement of the gray matter, the anterior and posterior horns
projecting' towards the surface, each half of the cord is divided, more or less
completely, into three columns, anterior, middle, and posterior ; the anterior and
middle being joined to form the antero-lateral column, as the anterior horn does
not quite reach the surface.
The gray commissure, which connects the two crescentic masses of gray matter,
is separated from the bottom of the anterior median fissure by the anterior white
commissure ; and, from the bottom of the posterior fissure by the posterior white
commissure. The gray commissure consists of a transverse band of gray matter,
and of white fibres, derived from the opposite half of the cord and the posterior
roots of the nerves. The anterior commissure is
Fig. 256.— -Transverse Sections formed, partly of fibres from the anterior column,
of the Cord. an(j partiy from ^ fiDrils of the anterior roots of
the spinal nerves, which decussate as they pass across
from one to the other side.
The mode of arrangement of the gray matter, and
Opposite Middle of Cervical re$s its amount in proportion to the white, vary in different
parts of the cord. Thus, the posterior horns are
long and narrow, in the cervical region; short and
narrower, in the dorsal; short, but wider, in the
lumbar region. In the cervical region, the crescentic
portions are small, the white matter more abundant
opposite Middle. <$• Dorsal ret* than in any other region of the cord. In the dorsal
region, the gray matter is least developed, the white
matter being also small in quantity. In the lumbar
region, the gray matter is more abundant than in
any other region of the cord. Towards the lower
cpposit* zumiar rryion, end of the cord, the white matter gradually ceases.
The crescentic portions of the gray matter soon blend
into a single mass, which forms the only constituent of its extreme point.
The white substance of the cord consists of transverse, oblique, and longitudinal fibres, with
oloodvessels and connective tissue.
rYhz transverse fibres proceed from the gray substance, and form with each other a kind of
plexus between the bundles of longitudinal fibres with which many are continuous ; while others
reach the surface of the cord through fissures containing connective tissue. Within the gray
substance thev are continuous with the roots of the nerves, the processes of the nerve cells, and
with the anterior and posterior commissures. The oblique fibres proceed from the gray substance
both upwards and downwards : they form the deep strata of the white columns, and, after running
SPINAL CORD.
505
Fig. 257. — Transverse Section of the gray substance
of the spinal cord, near the middle of the
dorsal region. Magnified 13 diameters.
g,t ^>*
a variable length become superficial. The longitudinal fibres are more superficial, run nearly
parallel with each other, and form the greater portion of the white columns.
The gray substance of the cord con-
sists of, 1. Nerve fibres of variable, but
smaller, average diameter than those of
the columns. 2. Nerve cells of various
shapes and sizes, with from two to eight
processes. 3. Bloodvessels and con-
nective tissue.
Each lateral half of the gray sub-
stance is divided into an anterior and
posterior horn, and the tractus inter-
medio lateralis, or lateral part of the
gray substance between the anterior
aud posterior cornua.
The posterior horn consists of two
parts, the caput cornu, or expanded ex-
tremity of the horn (fig. 257), round
which is the lighter space or lamina,
the gelatinous substance; and the cervix
cornu, or remaining narrow portion of
the horn, as far forwards as the central
canal.
The gelatinous substance contains
along its border a series of large nerve
cells ; but more internally consists of a
stratum of small cells traversed by
transverse, oblique, and longitudinal
fibres (figs. 258 and 259).
Fig. 258. — Transverse Section of the gray substance of the spinal cord through the middle of the
lumbar enlargement. On the left side the groups of large cells are seen ; on the right side
the course of the fibres without the cells. Magnified 13 diameters.
i.fc.ftr&SV'f
Nearly the whole inner half of the cervix is occupied by a remarkable and important column
of nerve cells, called the posterior vesicular column (fig. 257), which varies in size and appearance
in different regions of the cord, and is intimatelv connected with the posterior roots of the
nerves.
506
NERVOUS SYSTEM.
Fig. 259.— Longitudinal Section of the
white and gray substance of the
spinal cord, through the middle of the
lambar enlargement. Mag. 14 diam.
Within and along the outer border of the cervix are several thick bundles of longitudinal
fibres, represented in the adjoining figure by the dark spots ; other bundles of the same kind
may be seen in the gray substance along the line of junction of the caput with the cervix cornu
(fig. 258).
The anterior horn of the gray substance in the cervical and lumbar swellings, where it gives
origin to the nerves of the extremities, is much larger than in any other region, and contains
several distinct groups of large and variously shaped cells. This is well shown on comparing
the above figures.
The tractus intermedia lateralis (fig. 257) extends
from the upper part of the lumbar to the lower part
of the cervical enlargement, and consists of variously
shaped cells, which are smaller than those of the
anterior cornu. In the neck above the cervical en-
largement, a similar tract reappears, and is traversed
by the lower part of the spinal accessory nerve.
Origin of the Spinal Nerves. The posterior roots
are larger than the anterior; but their component
filaments are finer and more delicate. They are all
attached immediately to the posterior columns only,
and decussate with each other in all directions through
the columns; but some of them pass through the
gray substance into both the lateral and anterior
columns. Within the gray substance, they run lon-
gitudinally upwards and downwards ; transversely
through the posterior commissure to the opposite
side ; and into the anterior cornu of their own side
(figs. 258 and 259).
The anterior roots are attached exclusively to the
anterior columns, or rather to the anterior part of ihe
antero-lateral columns ; for there is no antero-lateral
fissure dividing the anterior from the lateral column.
Within the gray substance, the fibrils cross each other,
and diverge in all directions like the expanded hairs
of abrush (figs. 258 and 259), some of them running more
or less longitudinally upwards and downwards ; and
others decussating with those of the opposite side
through the anterior commissure in front of the cen-
tral canal.
All the fibres of both roots of the nerves proceed
through the white columns into the gray substance,
with, perhaps, the exception of some which appear to
run longitudinally in the posterior columns ; but
whether these latter fibres of the posterior roots ulti-
mately enter the gray substance of the cord after a
very oblique course, or whether they proceed upwards
to the brain, is uncertain.'
6e(at
Salsl'ctnce
Grey
Substance
MtT Boots
The Central Canal.
In the foetus, until after the sixth month, a canal, continuous with the general
ventricular cavity of the brain, extends throughout the entire length of the spinal
cord, formed by the closing-in of a previously open groove.
In the adult, this canal can only be seen at the upper part of the cord, extending
from the point of the calamus scriptorius, in the floor of the fourth ventricle, for
about half an inch down the centre of the cord, where it terminates in a cul-de-
sac ; the remnant of the canal being just visible in a section of the cord, as a
small, pale spot, corresponding to the centre of the gray commissure, its cavity
being lined with a layer of cylindrical ciliated epithelium. In some cases, this
canal remains pervious throughout the whole length of the cord.
1 The above description, and accompanying illustrations, kindly furnished me by my friend,
Mr. Lockhart Clarke, embodies a condensed account of his laborious and extensive observations
on the structure of the spinal cord. For further information on this subject, vide Phil. Traus.
iS51— 1853, Part iii. ; 1858, Part i. ; 1859, Part i.
DURA MATER. 50?
THE BRAIN AND ITS MEMBRANES.
Dissection. To examine the brain with its membranes, the skull-cap should first be removed.
This may be effected by sawing through the external table, commencing, in front, about an inch
above the margin of the orbit, and extending, behind, to a level with the occipital protuberance.
The internal table must then be broken through with the chisel and hammer, to prevent injury
to the investing membranes or brain, and, after having been loosened, it should be forcibly detached,
when the dura mater will be exposed. The adhesion between the bone and the dura mater is
very intimate, and much more so in the young subject than in the adult.
The membranes of the brain are, the dura mater, arachnoid membrane, and pia
mater.
Dura Matee.
The dura mater is a thick and dense inelastic fibrous membrane, which lines
the interior of the skull. Its outer surface is rough and fibrillated, and adheres
closely to the inner surface of the bones, forming their internal periosteum, this
adhesion being more intimate opposite the sutures and at the base of the skull ;
at the margin of the foramen magnum it becomes continuous with the dura
mater lining the spinal canal. Its inner surface is smooth and epitheliated,
being lined by the parietal layer of the arachnoid. The dura mater is, therefore,
a fibro-serous membrane, composed of an external fibrous lamella, and an internal
serous layer. It sends numerous processes inwards, into the cavity of the skull,
for the support and protection of the different parts of the brain ; it is also pro-
longed to the outer surface of the skull, through the various foramina which
exist at its base, where it is continuous with the pericranium; and 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 caecum ; it lines the
olfactory groove, and sends a series of tubular prolongations round the filament;
of the olfactory nerves as they pass through the cribriform foramina ; a prolonga-
tion is also continued through the sphenoidal fissure into the orbit, and another
is continued into the same cavity through the optic foramen, forming a sheath for
the optic nerve, which is continued as far as the eyeball. In certain situations in
the skull already mentioned, the fibrous layers of this membrane subdivide, to
form sinuses for the passage of venous blood. Upon the upper surface of the
dura mater, in the situation of the longitudinal sinus, may be seen numerous
small whitish bodies, the gland ul® Pacchioni.
Structure. The dura mater consists of white fibrous and elastic tissues, arranged
in flattened laminae, which intersect one another in every direction. ,
Its arteries are very numerous, but are chiefly distributed to the bones. Those
found in the anterior fossa are the anterior meningeal, from the anterior and
posterior ethmoidal, and internal carotid. In the middle fossa are the middle and
small meningeal, from the internal maxillary, and a third branch from the
ascending pharyngeal, which enters the skull through the foramen lacerum basis
cranii. In the posterior fossa, are the posterior meningeal branch of the occipital,
which enters the skull through the jugular foramen; the posterior meningeal, from
the vertebral ; and occasionally meningeal branches from the ascending pharyn-
geal, which enter the skull, one at the jugular foramen, the other at the anterior
condyloid foramen.
The veins, which return the blood from the dura mater, and partly from the
bones, anastomose with the diploic veins. These vessels terminate in the various
sinuses, with the exception of two which accompany the middle meningeal artery;
these pass from the skull at the foramen spinosum.
The nerves of the dura mater are, the recurrent branch of the fourth, and fila-
ments from the Casserian ganglion, the ophthalmic nerve, and sympathetic.
The so-called glandulae Pacchioni are numerous small whitish granulations,
usually collected into clusters of variable size, which are found in the following
situations : 1. Upon the outer surface of the dura mater, in the vicinity of the
508 NERVOUS SYSTEM.
superior longitudinal sinus, being received into little depressions on the inner
surface of the calvarium. 2. On the inner surface of the dura mater. 3. In the
superior longitudinal sinus. 4. On the pia mater near the margin of the
hemispheres.
These bodies are not glandular in structure, but consist of a fibro-cellular matrix
originally developed from the pia mater ; by their growth, they produce absorption
or separation of the fibres of the dura mater; in a similar manner they make their
way into the superior longitudinal sinus, where they are covered by the lining
membrane. The cerebral layer of the arachnoid in the situation of these growths
is usually thickened and opaque, and adherent to the parietal portion.
These bodies are not found in infancy, and very rarely until the third year.
They are usually found after the seventh year ; and from this period they increase
in number as age advances. Occasionally they are wanting.
Processes of the Dura Mater.
The processes of the dura mater, sent inwards into the cavity of the skull, are
three in number, the falx cerebri, the tentorium cerebelli, and the falx cerebelli.
The falx cerebri, so named from its sickle-like form, is a strong arched process
of the dura mater, which descends vertically in the longitudinal fissure between the
two hemispheres of the brain. It is narrow in front, where it is attached to the
crista galli process 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 as far back as the internal occipital protuberance.
In this situation, it is broad, and contains the superior longitudinal sinus. Its
lower margin is free, concave, and presents a sharp curved edge which contains
the inferior longitudinal sinus.
The tentorium cerebelli, so named from its tent-like form, is an arched lamina of
dura mater, elevated in the middle, and inclining downwards towards its cir-
cumference. It covers the upper surface of the cerebellum, supporting the posterior
lobes of the brain, and preventing their pressure upon it. It is attached, behind,
by its convex border, to the transverse ridges upon the inner surface of the occi-
pital bone, and there incloses the lateral sinuses ; in front, to the superior margin
of the petrous portion of the temporal bone, inclosing the superior petrosal sinuses,
and from the apex of this bone, on each side, is continued to the anterior and
posterior clinoid processes. Along the middle line of its upper surface, the pos-
terior border of the falx cerebri is attached, the straight sinus being placed at
their point of junction. Its anterior border is free and concave, and presents a
large oval opening for the transmission of the crura cerebri.
The falx cerebelli is a small triangular process of dura mater, 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.
Arachnoid Membrane.
The arachnoid (apa^, fZSoj, like a spider's web), so named from its extreme
thinness, is the serous membrane which, envelops the brain, and is then reflected
on the inner surface of the dura mater. Like other serous membranes, it is a
shut sac, and consists of a parietal and a visceral layer.
The parietal layer covers the inner surface of the dura mater,1 and gives this
membrane the smooth and polished surface which it presents ; it is also reflected
over those processes which separate the hemispheres of the brain and cerebellum.
1 Kolliker denies this ; and states, that the inner surface of the dura mater is covered with
pavement epithelium, but has no other investment which can be regarded as a parietal layer of
the arachnoid.
PIA MATER. 509
The visceral layer invests the brain more loosely, being separated from direct
contact with the cerebral substance by the pia mater, and a quantity of loose areolar
tissue, the sub-arachnoidean. 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 sulci between them. At the base of the brain, the arachnoid
is thicker, and slightly opaque towards the central part ; it covers the anterior
lobes, is extended across between the two middle lobes, so as to leave a considerable
interval between it and the brain, the anterior sub-arachnoidean spiace; it is closely
adherent to the pons and under surface of the cerebellum ; but between the hemi-
spheres of the cerebellum and the medulla oblongata, another considerable interval
is left between it and the brain, called the posterior sub-arachnoidean space. These
two spaces communicate together across the crura cerebri. The arachnoid mem-
brane surrounds the nerves which arise from the brain, and incloses them in loose
sheaths as far as their point of exit from the skull, where it becomes continuous
with the parietal layer.
The sub-arachnoid space is the interval between the arachnoid and pia mater :
this space is narrow on the surface of the hemispheres ; but at the base of the
brain, a wide interval is left between the two middle lobes, and behind, between
the hemispheres of the cerebellum and the medulla oblongata. This space is the
seat of an abundant serous secretion, the cerebro-spinal fluid, which fills up the
interval between the arachnoid and pia mater. The sub-arachnoid space usually
communicates with the general ventricular cavity of the brain, by means of an
opening in the inferior boundary of the fourth ventricle.
The sac of the arachnoid also contains serous fluid ; this is, however, small in
quantity compared with the cerebro-spinal fluid.
Structure. The arachnoid consists of bundles of white fibrous and elastic tissues
intimately blended together. Its outer surface is covered with a layer of scaly
epithelium. It is destitute of vessels, and the existence of nerves in it has not
been satisfactorily demonstrated.
The cerebro-spinal fluid fills up the sub-arachnoid space, keeping the opposed
surfaces of the arachnoid membrane in contact. It is a clear, limpid fluid, having
a saltish taste, and a slightly alkaline reaction. According to Lassaigne, it con-
sists 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.
Pia Mater.
The Pia Mater is a vascular membrane, and derives its blood from the internal
carotid and vertebral arteries. It consists of a minute plexus of bloodvessels,
held together by an extremely fine areolar tissue. It invests the entire surface
of the brain, dipping down between the convolutions and laminae, and is prolonged
iuto the interior, forming the velum interpositum and choroid plexuses of the
fourth ventricle. Upon the surface of the hemispheres, where it covers the gray
matter of the convolutions, it is very vascular, and gives off from its inner surface
a multitude of minute vessels, which extend perpendicularly for some distance
into the cerebral substance. At the base of the brain, in the situation of the
substantia perforata and locus perforatus, a number of long straight vessels are
given off, which pass through the white matter 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. Upon the crura cerebri and pons Varolii, its
characters are altogether changed; it here presents a dense fibrous structure,
marked only by slight traces of vascularity.
According to Fohmann and Arnold, this membrane contains numerous lym-
phatic vessels. Its nerves are derived from the sympathetic, and also from the
510 NERVOUS SYSTEM.
third, sixth, seventh, eighth, and spinal accessory. They accompany the branches
of the arteries.
The Brain.
The brain {encephalon) is that portion of the cerebro-spinal axis that is con-
tained in the cranial cavity. It is divided into fonr principal parts, viz : the
cerebrum, the cerebellum, the pons Varolii, and medulla oblongata.
The cerebrum forms the largest portion of the encephalic mass, and occupies a
considerable part of the cavity of the cranium, resting in the anterior and middle
fossas of the base of the skull, and separated posteriorly from the cerebellum by
the tentorium cerebelli. About the middle of its under surface, is a narrow con-
stricted portion, part of which, the crura cerebri, is continued onwards into the
pons Varolii below, and through it to the medulla oblongata and spinal cord ;
whilst another portion, the crura cerebelli, passes down into the cerebellum.
The cerebellum (little brain or after-brain) is situated in the inferior occipital
fossse, being separated from the under surface of the posterior lobes of the cere-
brum by the tentorium cerebelli. It is connected to the rest of the encephalic
mass by means of connecting bands, called crura; of these, two ascend to the
cerebrum, two descend to the medulla oblongata, and two blend together in front,
forming the pons Varolii.
Therms Varolii is that portion of the encephalic mass which rests upon the
upper part of the basilar process. It constitutes the bond of union of the various
segments above-named, receiving, above, the crura from the cerebrum ; at the
sides, the crura from the cerebellum; and being connected, below, with the
medulla oblongata.
The medulla oblongata extends from the lower border of the pons Varolii to
the upper part of the spinal cord. It lies beneath the cerebellum, resting on the
lower part of the basilar groove of the occipital bone.
Weight of the encephalon. The average weight of the brain, in the adult male,
is 49 \ oz., or a little more than 3 lbs. avoirdupois; that of the female, 44 oz.; the
average difference between the two being from 5 to 6 oz. The prevailing weight
of the brain, in the male, ranges between 46 oz. and 53 oz. ; and in the female,
between 41 oz. and 47 oz. In the male, the maximum weight out of 278 cases
was 65 oz., and the minimum weight 34 oz. The maximum weight of the adult
female brain, out of 191 cases, was 56 oz., and the minimum weight 31 oz. It
appears that the weight of the brain increases rapidly up to the seventh year,
more slowly to the period between sixteen and twenty, and still more slowly to
that between thirty and forty, when it reaches its maximum. Beyond this period,
as age advances and the mental faculties decline, the brain diminishes slowly in
weight, about an ounce for each subsequent decennial period. These results apply
alike to both sexes.
The size of the brain appears to bear a general relation to the intellectual
capacity of the individual. Cuvier's brain weighed rather more than 64 oz., that
of the late Dr. Abercrombie 63 oz., and that of Dupuytren 62 J oz. On the other
hand, the brain of an idiot seldom weighs more than 23 oz.
The human brain is heavier than that of all the lower animals excepting
the elephant and whale. The brain of the former weighs from 8 lbs. to 10 lbs.;
and that of the whale, in a specimen seventy-five feet long, weighed rather more
than 5 lbs.
Medulla Oblongata.
The medulla oblongata is the upper enlarged part of the spinal cord, and extends
Crom the upper border of the atlas to the lower border of the pons Varolii. It is
directed obliquely downwards and backwards, its anterior surface resting on the
basilar groove of the occipital bone, its posterior surface being received into the
fossa between the hemispheres of the cerebellum, forming the floor of the fourth
MEDULLA OBLONGATA.
511
ventricle. It is pyramidal in form, its broad, extremity directed upwards, its
lower end being narrow at its point of connection with the cord. It measures an
inch and a quarter in length, three-quarters of an inch in breadth at its widest
part, and half an inch in thickness. Its surface is marked, in the median line, in
front and behind, by an anterior and posterior median fissure, which are con-
tinuous with those of the spinal cord. The anterior fissure contains a fold of
pia mater, and terminates just below the pons in a cul-de-sac, the foramen ca?cum.
The posterior is a deep but narrow fissure, continued upwards along the floor of
the fourth ventricle, where it is finally lost. These two fissures divide the
medulla into two symmetrical halves, each lateral half being subdivided by
minor grooves into four columns, which, from before backwards, are named, the
anterior pyramid, lateral tract and olivary body, the restiform body, and the posterior
pyramid.
The anterior pyramids or corpora pyramidalia are two pyramidal-shaped
bundles of white matter, placed one on either side of the anterior median fissure,
and separated from the olivary body,
Which is external to them, by a slight FiS- 260.— Medulla Oblongata and Pods Varolii.
j • A , ,1 i i i n?i Anterior Surtace.
depression. At the lower border ot the
pons they are somewhat constricted;
they then become enlarged, and taper
slightly as they descend, being con-
tinuous below with the anterior co-
lumns of the cord. On separating the
pyramids below, it will be observed
that the innermost fibres of the two
form from four to five bundles on each
side, which decussate with one another ;
this decussation, however, is not formed
entirely of fibres from the pyramids,
but mainly from the deep portion of
the lateral columns of the cord which
pass forwards to the surface between
the diverging anterior columns. The
outermost fibres do not decussate ; they
are derived from the anterior columns
of the cord, and are continued directly
upwards through the pons Varolii.
Lateral tract and olivary body. The lateral tract is continuous with the lateral
column of the cord. Below, it is broad, and includes that part of the medulla
between the anterior pyramid and restiform body ; but, above, it is pushed a little
backwards, and narrowed by the projection forwards of the olivary body.
The olivary bodies are two prominent, oval masses, situated behind the anterior
pyramids, from which they are separated by slight grooves. They equal, in
breadth, the anterior pyramids, are a little broader above than below, and are
about half an inch in length, being separated, above, from the pons "Varolii, by a
slight depression. Numerous white fibres, fibrse arciformes, are seen winding
round the lower end of each body ; sometimes crossing their surface.
The restiform bodies are the largest columns of the medulla, and continuous,
below, with the posterior columns of the cord. They are two rounded, cord-like
eminences, placed between the lateral tracts, in front, and the posterior pyramids,
behind; from both of which they are separated by slight grooves. As they
ascend, they diverge from each other, assist in forming the lateral boundaries of
the fourth ventricle, and then enter the corresponding hemisphere of the cere-
bellum, forming its inferior peduncle, from which it is probable that some fibres
are continued from them into the cerebrum.
The posterior pyramids or fasciculi graciles are two narrow, white cords, placed
one on each side of the posterior median fissure, and separated from the restiform
512
NERVOUS SYSTEM.
Fig. 2G1. — Posterior Surface of Medulla
Oblongata.
bodies by a narrow groove. They consist entirely of white fibres, and are con
tinuous with the posterior median columns of the spinal cord. These bodies lie
at first in close contact. Opposite the
apex of the fourth ventricle, they form
an enlargement, the processus clavatus, and
then, diverging, are lost in the correspond-
ing restiform body. The upper part of
the posterior pyramids forms the lateral
boundaries of the calamus scriptorius.
The posterior surface of the medulla
oblongata forms part of the floor of the
fourth ventricle. It is of a triangular
form, bounded on each side by the di-
verging posterior pyramids, and is that
part of the ventricle which, from its
resemblance to the point of a pen, is
called the calamus scriptorius. The di-
vergence of the posterior pyramids and
the restiform bodies opens to view the
gray matter of the medulla, which is con-
tinuous, below, with the gray commissure
of the cord. In the middle line is seen a
longitudinal furrow, continuous with the
posterior median fissure of the cord, ter-
minating, below, at the point of the ven-
tricle, in a cul-de-sac, the ventricle of
Arantius, which descends into the medulla
for a slight extent. It is the remains of a canal, which, in the foetus, extends
throughout the entire length of the cord.
Structure. The columns of the cord are directly continuous with those of the
medulla oblongata, below; but, higher up, both the white and gray constituents
are re-arranged before they are continued upwards to the cerebrum and cere-
bellum.
The anterior pyramid is composed of fibres derived from the anterior column
of the cord of its own side, and from the lateral column of the opposite half of
the cord, and is continued upwards into the cerebrum and cerebellum. The
cerebellar fibres form a superficial and deep layer, which pass beneath the olive
to the restiform body, and spread out into the structure of the cerebellum. A
deeper fasciculus incloses the olivary body, and, receiving fibres from it, enters
the pons as the olivary fasciculus or
Fir. 2b2. — Transverse Section of Medulla .en . t , ,i i • r. o n-\ n
Oblongata. fillet; but the cbiei mass 01 fibres trom
the pyramid, the cerebral fibres, enter
the pons in their passage upwards to
the cerebrum. The anterior pyramids
contain no gray matter.
The lateral tract is continuous, be-
low, with the lateral column of the cord.
Its fibres pass in three different direc-
tions. The most external join the
restiform body, and pass to the cerebellum. The internal, more numerous, pass
forwards, pushing aside the fibres of the anterior column, and form part of the
opposite anterior pyramid. The middle fibres ascend, beneath the olivary body,
to the cerebrum, passing along the back of the pons, and form, together with
fibres from the restiform body, the fasciculi teretes, in the floor of the fourth
ventricle.
Olivary hody. If a transverse section is made through either olivary body, it
will be found to consist of a small ganglionic mass, deeply imbedded in the medulla,
Tntcrior Tietare-
Fasciculi Terete!
JUstrjvrm ~Bo3tf
Olivary Body
A ntrriar Pyramid.
STRUCTURE OF THE MEDULLA OBLONGATA.
513
partly appearing on the surface as a smooth, olive-shaped eminence (fig. 262). It
consists, externally, of white substance ; and, internally, of a gray nucleus, the
corpus dentatum. The gray matter is arranged in the form of a hollow capsule,
open at its upper and inner part, and presenting a zig-zag or dentated outline.
White fibres pass into or from the interior of this body, by the aperture in the
posterior part of the capsule. They join with those fibres of the anterior column
which ascend on the outer side, and beneath the olive, to form the olivary fasci-
culus, which ascends to the cerebrum.
Fig. 2G3. — The Columns of the Medulla Oblongata, and their Connection with the
Cerebrum and Cerebellum.
Medulla Oblongata
The restiform body is formed chiefly of fibres from the posterior column of the
cord ; but it receives some from the lateral column, and a fasciculus from the
anterior, and is continued, upwards, to the cerebrum and cerebellum. On entering
the pons, it divides into two fasciculi, above the point of the fourth ventricle.
The most external one enters the cerebellum ; the inner one joins the posterior
pyramid, is continued up along the fourth ventricle, and, joining the fasciculi
teretes, passes up to the cerebrum.
Septum of the medulla oblongata. Above the decussation of the anterior
pyramids, numerous white fibres extend, from behind forwards, in the median
line, forming a septum, which subdivides the medulla into two lateral halves.
Some of these fibres emerge at the anterior median fissure and form a band which
curves round the lower border of the olivary body, or passes transversely across
it, and round the sides of the medulla, forming the arc/form fibres of Rolando.
Others appear in the floor of the fourth ventricle, issuing from the posterior
median fissure, and form the white striae in that situation.
Gray matter of the medulla oblongata. The gray matter of the medulla is a
continuation of that contained in the interior of the spinal cord, besides a series
of special deposits or nuclei.
In the lower part of the medulla, the gray matter is arranged as in the cord,
but, at the upper part, it becomes more abundant, and is disposed with less
apparent regularity, becoming blended with all the white fibres, except the
anterior pyramids. The part corresponding to the transverse gray commissure
of the cord is exposed to view in the floor of the medulla oblongata, by the
514 NERVOUS SYSTEM.
divergence of the restiform bodies, and posterior pyramids, becoming blended with
the ascending fibres of the lateral column, and thus forming the fasciculi teretes.
The lateral crescentic portions, but especially the posterior horns, become enlarged,
blend with the fibres of the restiform bodies, and form the tuberculo cinereo of
Rolando.
Special deposits of gray matter are found both in the anterior and posterior
parts of the medulla; in the former situation, forming the corpus dentatum
within the olivary body, and, in the latter, a series of special masses, or nuclei,
connected with the roots of origin of the spinal accessory, vagus, glosso-pharyn-
geal, and hypoglossal nerves. It thus appears that the closest analogy in
structure, and also probably in general endowments, exists between the medulla
oblongata and the spinal cord. The larger size and peculiar form of the medulla
depending on the enlargement, divergence, and decussation of the various
columns ; and also from the addition of special deposits of gray matter in the
olivary bodies and other parts, evidently in adaptation to the more extended range
of function which this part of the cerebro-spinal axis possesses.
PONS VAROLII.
The pons Varolii (mesocephale, Chaussier) is the bond of union of the various
segments of the encephalon, connecting the cerebrum above, the medulla oblongata
below, and the cerebellum behind. It is situated above the medulla oblongata,
below the crura cerebri, and between the hemispheres of the cerebellum.
Its under surface presents a broad transverse band of white fibres, which arches
like a bridge across the upper part of the medulla, extending between the two
hemispheres of the cerebellum. This surface projects considerably beyond the
level of these parts, is of a quadrangular form, rests upon the basilar groove of
the occipital bone, and is limited before and behind by very prominent margins.
It presents along the middle line a longitudinal groove, wider in front than behind,
which lodges the basilar artery ; numerous transverse striae are also observed on
each side, which indicate the course of its superficial fibres.
Its upper surface forms part of the floor of the fourth ventricle, and at each side
it becomes contracted into a thick rounded cord, the crus cerebelli, which enters
the substance of the cerebellum, constituting its middle peduncle.
• Structure. The pons Varolii consists of alternate layers of transverse and longi-
tudinal fibres intermixed with gray matter (fig. 263).
The transverse fibres connect together the two lateral hemispheres of the
cerebellum, and constitute its great transverse commissure. They consist of a
superficial and a deep layer. The superficial layer passes uninterruptedly across
the surface of the pons, forming a uniform layer, consisting of fibres derived from
the crus cerebelli on each side, which meet in the median line. The deep layer
of transverse fibres decussates with the longitudinal fibres continued up from the
medulla, and contains much gray matter between its fibres.
The longitudinal fibres are continued up through the pons. 1. From the
anterior pyramidal body. 2. From the olivary body. 3. From the lateral and
posterior columns of the cord, receiving special fibres from the gray matter of the
pons itself.
1. The fibres from the anterior pyramid ascend through the pons, imbedded
between two layers of transverse fibres, being subdivided in their course into
smaller bundles ; at the upper border of the pons they enter the crus cerebri,
forming its fasciculated portion.
2. The olivary fasciculus divides in the pons into two bundles, one of which
ascends to the corpora quadrigemina ; the other is continued to the cerebrum with
the fibres of the lateral column.
3. The fibres from the lateral and posterior columns of the cord, with a bundle
from the olivary fasciculus, are intermixed with much gray matter, and appear in
CEREBRUM. 515
the floor of the fourth ventricle as the fasciculi teretes; they ascend to the deep or
cerebral part of the crus cerebri.
Foville considers that a few fibres from each of the longitudinal tracts of the
medulla turn forwards, and are continuous with the transverse fibres of the pons.
Septum. The pons is subdivided into two lateral halves by a median septum,
which extends through its posterior half. The septum consists of antero-posterior
and transverse fibres. The former are derived from the floor of the fourth ven-
tricle and from the transverse fibres of the pons, which bend backwards before
passing across to the opposite side. The latter are derived from the floor of the
fourth ventricle ; they pierce the longitudinal fibres, and are then continued across
from one to the other side of the medulla, piercing the antero-posterior fibres.
The two halves of the pons, in front, are connected together by transverse com-
missural fibres.
CEREBRUM.
Upper Surface.
The Cerebrum, in man, constitutes the largest portion of the encephalon. Its
upper surface is of an ovoidal form, broader behind than in front, convex in its
general outline, and divided into two lateral halves or hemispheres, right and left,
by the great longitudinal fissure. This fissure extends throughout the entire
length of the cerebrum in the middle line, reaching down to the base of the
brain in front and behind, but interrupted in the middle by a broad transverse
commissure of white matter, the corpus callosum, which connects the two hemi-
spheres together. This fissure lodges the falx cerebri, and indicates the original
development of the brain by two lateral halves.
Each hemisphere presents an outer surface, which is convex, to correspond
with the vault of the cranium ; an inner surface, flattened, and in contact with the
opposite hemisphere, the two inner surfaces forming the sides of the longitudinal
fissure ; and an under surface or base, of more irregular form, which rests, in
front, on the anterior and middle fossae at the base of the skull, and, behind, upon
the tentorium.
Convolutions. If the pia mater is removed with the forceps, the entire surface
of each hemisphere will present a number of convoluted eminences, the convolu-
tions, separated from each other by depressions {sulci) of various depths. The
outer surface of each convolution, as well as the sides and bottom of the sulci
between them, are composed of gray matter, which is here called the cortical sub-
stance. The interior of each convolution is composed of white matter, and white
fibres also blend with the gray matter at the sides and bottom of the sulci. By
this arrangement the convolutions are admirably adapted to increase the amount
of gray matter without occupying much additional space, and also afford a greater
extent of surface, for the fibres to terminate in it. On closer examination, how-
ever, the gray matter of the cortical substance is found subdivided into four
layers, two of which are composed of gray and two of white substance. The
most external is an outer white stratum, not equally thick over all parts of the
brain, being most marked on the convolutions in the longitudinal fissure and on
the under part of the brain, especially on the middle lobe, near the descending
horn of the lateral ventricle. Beneath the latter is a thick reddish gray lamina,
and then another thin white stratum ; lastly, a thin stratum of gray matter, which
lies in close contact with the white fibres of the hemispheres ; consequently white
and gray laminae alternate with one another in the gray matter of the convolu-
tions. In certain convolutions, however, the cortical substance consists of no less
than six layers, three gray and three white, an additional white stratum dividing
the most superficial gray one into two ; this is especially marked in those convo-
lutions which are situated near the corpus callosum.
A perfect resemblance between the convolutions does not exist in all brains,
516
NERVOUS SYSTEM.
nor are they symmetrical on the two sides of the same brain. Occasionally the
free borders or the sides of a deep convolution present a fissured or notched
appearance.
The sulci are generally an inch in depth, but they vary in different brains, and
in different parts of the same brain, being usually deepest on the outer convex
surface of the hemispheres ; the deepest is situated on the inner surface of the
hemisphere, on a level with the corpus callosum, and corresponds to the projection
in the posterior horn of the lateral ventricle, the hippocampus minor.
The number and extent of the convolutions, as well as their depth, appear to
bear a close relation to the intellectual power of the individual, as is shown in
their increasing complexity of arrangement as we ascend from the lowest mam-
malia up to man. Thus they are absent in some of the lower orders of mammalia,
and they increase in number and extent through the higher orders. In man they
present the most complex arrangement. Again, in the child at birth before the
Fig. 264. — Upper Surface of the Brain, the Pia Mater having been removed.
Great Xonyi'lua'ixcl Fissurs
intellectual faculties are exercised, the convolutions have a very simple arrange-
ment, presenting few undulations ; and the sulci between them are less deep than
in the adult. In old age, when the mental faculties have diminished in activity,
the convolutions become much less prominently marked.
Those convolutions which are the largest and most constantly present are the
convolution of the corpus callosum, the convolution of the longitudinal fissure,
the supra-orbital convolution, and the convolutions of the outer surface of the
hemisphere.
BASE OF THE BRAIN. 517
The convolution of the corpus calhsum {gyrus fornicatus) is always well
marked. It lies parallel with the upper surface of the corpus callosura, com-
mencing on the under surface of the brain in front of the anterior perforated
space ; it winds round the curved border of the corpus callosum, and passes
along its upper surface as far as its posterior extremity, where it is connected
with the convolutions of the posterior lobe ; it then curves downwards and
forwards, embracing the cerebral peduncle, passes into the middle lobe, forming
the hippocampus major, and terminates just behind the point from whence it
arose.
The supra-orbital convolution on the under surface of the anterior lobe is well
marked.
The convolution of the longitudinal fissure bounds the margin of the fissure
on the upper surface of the hemisphere. It commences on the under surface of
the brain, at the anterior perforated space, passes forwards along the inner margin
of the anterior lobe, being here divided by a deep sulcus, in which the olfactory
nerve is received ; it then curves over the anterior and upper surface of the hemi-
sphere, along the margin of the longitudinal fissure, to its posterior extremity,
where it curves forwards along the under surface of the hemisphere as far as the
middle lobe.
The convolutions on the outer convex surface of the hemisphere, the general
direction of which is more or less oblique, are the largest and the most complicated
convolutions of the brain, frequently becoming branched like the letter Yin their
course upwards and backwards towards the longitudinal fissure : these convolutions
attain their greatest development in man, and are especially characteristic of the
human brain. They are seldom symmetrical on the two sides.
Under Surface or Base.
The under surface of each hemisphere presents a subdivision, as already
mentioned, into three lobes, named, from their position, anterior, middle, and
posterior.
The anterior lobe, of a triangular form, with its apex backwards, is somewhat
concave, and rests upon the convex surface of the roof of the orbit, being separated
from the middle lobe by the fissure of Sylvius. The middle lobe, which is more
prominent, is received into the middle fossa of the base of the skull. The posterior
lobe rests upon the tentorium, its extent forwards being limited by the anterior
margin of the cerebellum.
The various objects exposed to view on the under surface of the cerebrum in
the middle line are here arranged in the order in which they are met with from
before backwards.
Longitudinal fissure. Tuber cinereum.
Corpus callosum and its peduncles. Infundibulum.
Lamina cinerea. Pituitary body.
Olfactory nerve. Corpora albicantia.
Fissure of Sylvius. Posterior perforated space.
Anterior perforated space. Crura cerebri.
Optic commissure.
The longitudinal fissure partially separates the two hemispheres from one
another ; it divides the two anterior lobes in front, and, on raising the cerebellum
and pons, it will be seen completely separating the two posterior lobes, the inter-
mediate portion of the fissure being arrested by the great transverse band of white
matter, the corpus callosum. Of these two portions of the longitudinal fissure,
that which separates the posterior lobes is the longest. In the fissure between
the two anterior lobes the anterior cerebral arteries may be seen ascending to the
corpus callosum ; and at the back part of this portion of the fissure, the anterior
curved portion of the corpus callosum descends to the base of the brain.
518
NERVOUS SYSTEM.
The corpus callosum terminates at the base of the brain by a concave margin,
which is connected with the tuber cinereum through the intervention of a thin
layer of gray substance, the lamina cinerea. This may be exposed by gently
raising and drawing back the optic commissure. A broad white band may be
observed on each side, passing from the under surface of the corpus callosum
backwards and outwards, to the commencement of the fissure of Sylvius ; these
bands are called the peduncles of the corpus callosum. Laterally, the corpus
callosum extends into the anterior lobe. «
The lamina cinerea is a thin layer of gray substance, extending backwards
from the termination of the corpus callosum above the optic commissure to the
tuber cinereum ; it is continuous on either side with the gray matter of the anterior
perforated space, and forms the anterior part of the inferior boundary of the third
ventricle.
Fig. 265.— Base of the Brain.
M
The olfactory nerve, with its bulb, is seen on either side of the longitudinal
fissure, upon the under surface of each anterior lobe.
The fissure of Sylvius separates the anterior and middle lobes, and lodges the
middle cerebral artery. At its entrance is seen a point of medullary substance,
corresponding to a subjacent band of white fibres, connecting the anterior and
middle lobes, and called the fasciculus unciformis ; on following this fissure out-
wards, it divides into two branches, which inclose a triangular-shaped prominent
cluster of isolated convolutions, the island of Reil. These convolutions, from
being covered in by the sides of the fissure, are called the gyri operti.
BASE OF THE BRAIN. 519
The anterior perforated space is situated at the inner side of the fissure of
Sylvius. It is of a triangular shape, bounded in front by the convolution of the
anterior lobe and roots of the olfactory nerve ; behind, by the optic tract ; externally,
by the middle lobe and commencement of the fissure of Sylvius ; internally, it is
continuous with the lamina cinerea, and crossed by the peduncle of the corpus
callosum. It is of a grayish color, and corresponds to the under surface of the
corpus striatum, a large mass of gray matter, situated in the interior of the brain ;
it has received its name from being perforated by numerous minute apertures for
the transmission of small straight vessels into the substance of the corpus striatum.
The optic commissure is situated in the middle line, immediately behind the
lamina cinerea. It is the point of junction between the two optic nerves.
Immediately behind the diverging optic tracts, and between them and the
peduncles of the cerebrum [crura cerebri) is a lozenge-shaped interval, the inter-
peduncular space, in which are found the following parts, arranged in the following
order from before backwards : the tuber cinereum, infundibulum, pituitary body,
corpora albicantia, and the posterior perforated space.
The tuber cinereum is an eminence of gray substance, situated between the
optic tracts and the corpora albicantia ; it is connected with the surrounding parts
of the cerebrum, forms part of the floor of the third ventricle, and is continuous
with the gray substance in that cavity. From the middle of its under surface,
a conical tubular process of gray matter, about two lines in length, is continued
downwards and forwards to be attached to the posterior lobe of the pituitary body ;
this is the infundibulum. Its canal, funnel-shaped in form, communicates with
the third ventricle. :,
The pituitary body is a small, reddish-gray, vascular mass, weighing from five
to ten grains, and of an oval form, situated in the sella Turcica, in connection with
which it is retained by the dura mater which forms the inner wall of the cavernous
sinus. It is very vascular, and consists of two lobes, separated from one another
by a fibrous lamina. Of these, the anterior is the larger, of an oblong form, and
somewhat concave behind, where it receives the posterior lobe, which is round.
The anterior lobe consists externally of firm yellowish-gray substance, and inter-
nally of a soft pulpy substance of a yellowish-white color. The posterior lobe is
darker than the anterior. In the foetus it is larger proportionally than in the
adult, and contains a cavity which communicates through the infundibulum with
the third ventricle. In the adult it is firmer and more solid, and seldom "contains
any cavity. Its structure, especially the anterior lobe, is similar to that of the
ductless glands.
The corpora albicantia are two small round white masses, each about the size of
a pea, placed side by side immediately behind the tuber cinereum. They are formed
by the anterior crura of the fornix, hence called the bulbs of the fornix, which,
after descending to the base of the brain, are folded upon themselves, before passing
upwards to the thalami optici. They are composed externally of white substance,
and internally of gray matter ; the gray matter of the two being connected by a
transverse commissure of the same material. At an early period of foetal life
they are blended together into one large mass, but become separated about the
seventh month*.
The posterior perforated space or pons Tarini corresponds to a whitish-gray
substance, placed between the corpora albicantia in front, the pons Varolii behind,
and the crura cerebri on either side. It forms the back part of the floor of the
third ventricle, and is perforated by numerous small orifices for the passage of
bloodvessels to the thalami optici.
The crura cerebri or peduncles of the cerebrum are two thick cylindrical bundles
of white matter, which emerge from the anterior border of the pons, and diverge
as they pass forwards and outwards to enter the under part of either hemisphere.
Each crus is about three-quarters of an inch in length, and somewhat broader in
front than behind. They are marked upon their surface with longitudinal stria?,
and each is crossed, just before entering the hemisphere, by a flattened white band.
520 NERYOUS SYSTEM.
the optic tract, which is adherent by its upper border to the peduncle. In its
interior is contained a mass of dark-gray matter, called the locus niger. The third
nerves may be seen emerging from the inner side of either crus ; and the fourth
nerve winding around its outer side from above.
Each crus consists of a superficial and deep layer of longitudinal white fibres,
continued upwards from the pons, separated by a mass of gray matter, the locus
niger.
The superficial longitudinal fibres are continued upwards, from the anterior
pyramids to the cerebrum. They consist of coarse fasciculi, which form the free
part of the crus, and have received the name of the fasciculated portion of the
peduncle or crus.
The deep layer of longitudinal fibres is continued upwards, to the cerebrum,
from the lateral and posterior columns of the medulla, and from the olivary fasci-
culus, these fibres consisting of some derived from the same, and others from the
opposite lateral tract of the medulla. More deeply, is a layer of finer fibres,
mixed with gray matter, derived from the cerebellum, blended with the former.
The cerebral surface of the crus cerebri is formed of these fibres, and is named
the tegumentum.
The locus niger is a mass of gray matter, situated between the superficial and
deep layer of fibres above described. It is placed nearer the inner than the outer
side of this body.
The posterior lobes of the cerebrum are concealed from view by the upper
surface of the cerebellum, and pons Yarolii. When these parts are removed, the
two hemispheres are seen to be separated by the great longitudinal fissure, this
fissure being arrested, in front, by the posterior rounded border of the corpus
callosum.
Geneeal Aeeangement of the Paets composing the Ceeebeum.
As the peduncles of the cerebrum enter the hemispheres, they diverge from one
another, so as to leave an interval between them, the interpeduncular space. As
they ascend, the component fibres of each pass through two large masses of gray
matter, the ganglia of the brain, called the thalaini optici and corpora striata,
which project as rounded eminences from the upper and inner side of each
peduncle. The hemispheres are connected together, above these masses, by the
great transverse commissure, the corpus callosum, and the interval left between
its under surface, the upper surface of the ganglia, and the parts closing the
interpeduncular space, forms the general ventricular cavity. The upper part of
this cavity is subdivided into two by a vertical septum, the septum luciclum : and
thus the two lateral ventricles are formed. The lower part of this cavity forms
the third ventricle, which communicates with the lateral ventricles, above, and
with the fourth ventricle, behind. The fifth ventricle is the interval left between
the two layers composing the septum lucidum.
' Inteeioe of the Ceeebeum.
If the upper part of either hemisphere is removed with a scalpel, about half
an inch above the level of the corpus callosum, its internal white matter will be
exposed. It is an oval-shaped centre, of white substance, surrounded on all sides
by a narrow, convoluted margin of gray matter which presents an equal thickness
in nearly every part. This white central mass has been called the centrum ovale
minus. Its surface is studded with numerous minute red dots, the puncta vasculosa,
produced by the escape of blood from divided bloodvessels. In inflammation, or
great congestion of the brain, these are very numerous, and of a dark color. If
the remaining portion of one hemisphere is slightly separated from the other, a
broad band of white substance will be observed connecting them, at the bottom
of the longitudinal fissure : this is the corpus callosum. The margins of the
CORPUS CALLOSUM.
521
hemispheres, which overlap this portion of the brain, are called the labia cerebri.
Each labium is part of the convolution of the corpus callosum (gyrus fornicatus),
already described ; and the space between it and the upper surface of the corpus
callosum has been termed the ventricle of the corpus callosum.
The hemispheres should now be sliced off; to a level with the corpus callosum,
when the white substance of that structure will be seen connecting together both
hemispheres. The large expanse of medullary matter now exposed, surrounded
by the convoluted margin of gray substance, is called the centrum ovale majus of
Vieussens.
The corpus callosum is a thick stratum of transverse fibres, exposed at the
bottom of the longitudinal fissure. It connects the two hemispheres of the brain,
forming their great transverse commissure ; and forms the roof of a space in the
Fig. 266.— Section of the Brain. Made on a level with the Corpus Callosum.
interior of each hemisphere, the lateral ventricle. It is about four inches in
length, extending to within an inch and a half of the anterior, and to within two
inches and a half of the posterior, part of the brain. It is somewhat broader
behind than in front, and is thicker at either end than in its central part, being
thickest behind. It presents a somewhat arched form, from before backwards,
terminating anteriorly in a rounded border, which curves downwards and back-
wards, between the anterior Jobes to the base of the brain. In its course, it forms
a distinct bend, named the knee or genu, and the reflected portion, named the
beak or rostrum, becoming gradually narrower, is attached to the anterior cerebral
lobe, and is connected, through the lamina cinerea, with the optic commissure.
The reflected portion of th,e corpus callosum gives off, near its termination, two
522
NERVOUS SYSTEM.
bundles of white substance, which, diverging from one another, pass backwards,
across the anterior perforated space, to the entrance of the fissure of Sylvius.
They are called the peduncles of the corpus callosum. Posteriorly, the corpus
callosum forms a thick, rounded fold, which is free for a little distance, as it
curves forwards, and is then continuous with the fornix. On its upper surface,
its fibrous structure is very apparent to the naked eye, being collected into coarse,
transverse bundles. Along the middle line, is a linear depression, the raphe, bounded
laterally by two or more slightly elevated longitudinal bands, called the striae
longitudinales or nerves of Lancisi ; and, still more externally, other longitudinal
stria? are seen, beneath the convolutions, which rest on the corpus callosum. These
are the strioe longitudinales laterales. The under surface of the corpus callosum
Fig. 267.— The Lateral Ventricles of the Brain.
is continuous behind with the fornix, being separated from it in front by the
septum lucidum, which forms a vertical partition between the two ventricles. On
either side, the fibres of the corpus callosum penetrate into the substance of the
hemispheres, and connect together the anterior, middle, and part of the posterior
lobes. It is the large number of fibres derived from the anterior and posterior
lobes, which explains the great thickness of the two extremities of this commissure.
An incision should now be made through the corpus callosum, on either side of the raphe,
when two large irregular cavities will be exposed, which extend throughout the entire length of
each hemisphere. These are the lateral ventricles.
The lateral ventricles are serous cavities, formed by the upper part of the
general ventricular space in the interior of the brain. They are lined by a thin
diaphanous lining membrane, covered with ciliated epithelium, and moistened by a
LATERAL VENTRICLES. 523
serous fluid, which is sometimes, even in health, secreted in considerable quantity.
These cavities are two in number, one in each hemisphere, and they are separated
from each other by a vertical septum, the septum lucidum.
Each lateral ventricle consists of a central cavity or body, and three smaller
cavities or cornua, which extend from it in different directions. The anterior
cornu curves forwards and outwards, into the substance of the anterior lobe. The
posterior cornu, called the digital cavity, curves backwards into the posterior lobe.
The middle cornu descends into the middle lobe.
The central cavity or body of the lateral ventricle is triangular in form. It
is bounded, above, by the under surface of the corpus callosum, which forms the
roof of the cavity. Internally, is a vertical partition, the septum lucidum, which
separates it from the opposite ventricle, and connects the under surface of the
corpus callosum with the fornix. Its floor is formed by the following parts,
enumerated in their order of position, from before backwards, the corpus striatum,
taenia semicircularis, thalamus opticus, choroid plexus, corpus fimbriatum, and
fornix.
The anterior cornu is triangular in form, passing outwards into the anterior
lobe, and curving round the anterior extremity of the corpus striatum. It is
bounded, above and in front, by the corpus callosum; behind, by the corpus
striatum.
The posterior cornu or digital cavity curves backwards into the substance of
the posterior lobe, its direction being backwards and outwards, and then inwards.
On its floor is seen a longitudinal eminence, which corresponds with a deep sulcus
between two convolutions ; this is called the hippocampus minor. Between the
middle and posterior horns, a smooth eminence is observed, which varies consi-
derably in size in different subjects. It is called the eminentia collateralis.
The corpus striatum has received its name from the striated appearance which
its section presents, from white fibres diverging through its substance. The intra-
ventricular portion is a large pear-shaped mass, of a gray color externally ; its
broad extremity is directed forwards, into the forepart of the body, and anterior
cornu of the lateral ventricle ; its narrow end is directed outwards and backwards,
being separated from its fellow by the thalami optici ; it is covered by the serous
lining of the cavity, and crossed by some veins of considerable size. The extra-
ventricular portion is imbedded in the white substance of the hemisphere.
The tsenia semicircularis is a narrow, whitish, semitransparent band of medul-
lary substance, situated in the depression between the corpus striatum and thala-
mus opticus. Anteriorly, it descends in connection with the anterior pillar of the
fornix ; behind, it is continued into the descending horn of the ventricle, where
it becomes lost. Its surface, especially at its forepart, is transparent, and dense
in structure, and was called by Tarinus the horny band. It consists of longitu-
dinal white fibres, the deepest of which run between the corpus striatum and
thalamus opticus. Beneath it is a large vein, the vena corporis striati, which
receives numerous smaller veins from the surface of the corpus striatum, and
thalamus opticus, and terminates in the venae Galeni.
The choroid plexus is a highly vascular, fringe-like membrane, occupying the
margin of the fold of pia mater (velum interpositum), in the interior of the brain.
It extends, in a curved direction, across the floor of the lateral ventricle. In front,
where it is small and tapering, it communicates with the choroid plexus of the
opposite side, through a large oval aperture, the foramen of Monro. Posteriorly,
it descends into the middle horn of the lateral ventricle, where it joins with the
pia mater through the transverse fissure. In structure, it consists of minute and
highly vascular villous processes, the villi being covered by a single layer of
epithelium, composed of large round corpuscles, containing, besides a central
nucleus, a bright yellow spot. The arteries of the choroid plexus enter the ven-
tricle, at the descending cornu, and, after ramifying through its substance, send
branches into the substance of the brain. The veins of the choroid plexus ter-
minate in the venae Galeni.
524
NERVOUS SYSTEM.
The corpus fimbriatum, called also the tsenia hippocampi, is a narrow, white,
tape-like band, situated immediately behind the choroid plexus. It is the lateral
edge of the posterior pillar of the fornix, and is attached along the inner border of
the hippocampus major as it descends into the middle horn of the lateral ventricle.
It may be traced as far as the pes hippocampi.
The thalami optici and fornix will be described when more completely exposed,
in a later stage of the dissection of the brain.
The middle cornu should now be exposed, throughout its entire extent, by introducing the
little finger gently into it, and cutting through the hemisphere, between it and the surface, in the
direction of the cavity.
The middle or descending cornu, the largest of the three, traverses the middle
lobe of the brain, forming in its course a remarkable curve round the back of the'
Fig.
268. — The Fornix, Velum Interpositum, and Middle or Descending Cornu of
the Lateral Ventricle.
optic thalamus. It passes, at first, backwards, outwards, and downwards, and
then curves around the crus cerebri, forwards and inwards, nearly to the point of
the middle lobe, close to the fissure of Sylvius. Its upper boundary is formed
by the medullary substance of the middle lobe, and the under surface of the
thalamus opticus. Its lower boundary presents for examination the following
parts : The hippocampus major, pes hippocampi, pes accessorius, corpus fimbria-
tum, choroid plexus, fascia dentata, transverse fissure.
The hippocampus major or cornu ammonis, so called from its resemblance to
a ram's horn, is a white eminence, of a curved elongate form, extending along the
LATERAL VENTRICLE — MIDDLE CORNU. 525
entire length of the floor of the middle horn of the lateral ventricle. At its lower
extremity it becomes enlarged, and presents a number of rounded elevations with
intervening depressions, which, from presenting some resemblance to the claw of
an animal, is called the pes hippocampi. If a transverse section is made through
the hippocampus major, it will be seen that this eminence is the inner surface of
the convolution of the corpus callosum, doubled upon itself like a horn, the white
convex portion projecting into the cavity of the ventricle ; the gray portion being
on the surface of the cerebrum, the edge of which, slightly indented, forms the
fascia dentata. The white matter of the hippocampus major is continuous through
the corpus fimbriatum, with the fornix and corpus callosum.
The pes accessor ius or eminentia collateralis has been already mentioned, as a
white eminence, varying in size, placed between the hippocampus major and
minor, at the junction of the posterior with the descending cornu. Like the hippo-
campi, it is formed of white matter corresponding to one of the sulci, between
two convolutions protruding into the cavity of the ventricle.
The corpus fimbriatum is a continuation of the posterior pillar of the fornix,
prolonged, as already mentioned, from the central cavity of the lateral ventricle.
Fascia dentata. On separating the inner border of the corpus fimbriatum from
the choroid plexus, and raising the edge of the former, a serrated band of gray
substance, the edge of the gray substance of the middle lobe, will be seen beneath
it; this is the fascia dentata. Correctly speaking, it is placed external to the
cavity of the descending cornu.
The transverse fissure is seen on separating the corpus fimbriatum from the thal-
amus opticus. It is situated beneath the fornix, extending from the middle line
behind, downwards on either side, to the end of the descending cornu, being
bounded on one side by the fornix and the hemisphere, and on the other by the
thalamus opticus. Through this fissure the pia mater passes from the exterior of
the brain into the ventricles, to form the choroid plexuses. Where the pia mater
projects into the lateral ventricle, beneath the edge of the fornix, it is covered by
a prolongation of the lining membrane, which excludes it from the cavity.
The septum lucidum forms the internal boundary of the lateral ventricle. It
is a thin, semi-transparent septum, attached, above, to the under surface of the
corpus callosum ; below, to the anterior part of the fornix ; and, in front of this,
to the prolonged portion of the corpus callosum. It is triangular in form, broad
in front, and narrow behind, its surfaces looking towards the cavities of the ven-
tricles. The septum consists of two laminae, separated by a narrow interval, the
fifth ventricle.
Each lamina consists of an internal layer of white substance, covered by the
lining membrane of the fifth ventricle ; and an outer layer of gray matter, covered
by the lining membrane of the lateral ventricle. The cavity of the ventricle is
lined by a serous membrane, covered with epithelium, and contains fluid. In the
foetus, and in some animals, this cavity communicates, below, with the third
ventricle, but in the adult, it forms a separate cavity. In cases of serous effusion
into the ventricles, the septum is often found softened and partially broken
down.
The fifth ventricle may be exposed by cutting through the septum and attached portion of the
corpus callosum, with the scissors ; after examining which, the corpus callosum should be cut
across, towards its anterior part, and the two portions carefully dissected, the one forwards, the
other backwards, when the fornix will be exposed.
The fornix is a longitudinal lamella, of fibrous matter, situated beneath the
corpus callosum, with which it is continuous behind, but separated from it in front
by the septum lucidum. It may be described as consisting of two symmetrical
halves, one for either hemisphere. These two portions are joined together in the
middle line, where they form the body, but are separated from one another in
front and behind ; in front, forming the anterior crura, and behind, the posterior
crura.
526 NERVOUS SYSTEM.
The body of the fornix is triangular in form ; narrow in front, broad behind.
Its upper surface is connected, in the median line, to the septum lucidum in front,
and the corpus callosum behind. Its under surface rests upon the velum interpo-
situm, which separates it from the third ventricle, and the inner portion of the
optic thalami. Its lateral edges form, on each side, part of the floor of the lateral
ventricles, and are in contact with the choroid plexuses.
The anterior crura arch downwards towards the base of the brain, separated
from each other by a narrow interval. They are composed of white fibres, which
descend through a quantity of gray matter in the lateral walls of the third ven-
tricle, and are placed immediately behind the anterior commissure. At the base
of the brain, the white fibres of each crus form a sudden curve upon themselves,
spread out and form the outer part of., the corresponding corpus albicans, from
which point they may be traced upwards into the substance of the corresponding
thalamus opticus. The anterior crura of the fornix are connected in their course
with the optic commissure, the white fibres covering the optic thalamus, the
peduncle of the pineal gland, and the superficial fibres of the taenia semicircu-
laris.
The posterior crura, at their commencement, are intimately connected by their
upper surfaces with the corpus callosum ; diverging from one another, they pass
downwards into the descending horn of the lateral ventricle, being continuous
with the concave border of the hippocampus major. The lateral thin edges of
the posterior crura have received the name corpus fimbriatum, already described.
On the under surface of the fornix, towards its posterior part, between the diverg-
ing posterior crura, may be seen some transverse lines, and others longitudinal or
oblique. This appearance has been termed the lyra, from the fancied resemblance
it bears to the strings of a harp.
Between the anterior pillars of the fornix and the anterior extremities of the
thalami optici, an oval aperture is seen on each side, the foramen of Monro. The
two openings descend towards the middle line, and, joining together, lead into the
upper part of the third ventricle. These openings communicate with the lateral
ventricles on each side, and below with the third ventricle.
Divide the fornix across anteriorly, and reflect the two portions, the one forwards, the other
backwards, when the velum interpositum will be exposed.
The velum interpositum is a vascular membrane, reflected from the pia mater
into the interior of the brain through the transverse fissure, passing beneath the
posterior rounded border of the corpus callosum and fornix, and above the corpora
quadrigemina, pineal gland, and optic thalami. It is of a triangular form, and
separates the under surface of the body of the fornix from the cavity of the third
ventricle. Its posterior border forms an almost complete investment for the pineal
gland. Its anterior extremity, or apex, is bifid ; each bifurcation being continued
into the corresponding lateral ventricle, behind the anterior crura of the fornix,
forming the anterior extremity of the choroid plexus. On its under surface are
two vascular fringes, which diverge from each other behind, and project into the
cavity of the third ventricle. These are the choroid plexuses of the third ventricle.
To its lateral margins are connected the choroid plexuses of the lateral ventricles.
The arteries of the velum interpositum enter from behind, beneath the corpus
callosum. Its veins, the venee Galeni, two in number, run along its under sur-
face ; they are formed by the venee corporis striati, and the venaa plexus choroidis ;
the ven&e Galeni unite posteriorly into a single trunk, which terminates in the
straight sinus.
The velum interpositum should now be removed. This must be effected carefully, especially at
its posterior part, where it invests the pineal gland ; the thalami optici will then be exposed with
the cavity of the third ventricle between them (fig. 269).
The thalami optici are two large oblong masses, placed between the diverging
portions of the corpora striata ; they are of a white color, superficially ; internally,
THIRD VENTRICLE.
52T
they are composed of white fibres intermixed with gray matter. Each thalamus
rests upon its corresponding crus cerebri, which it embraces. Externally, it is
bounded by the corpus striatum, and taania semicircularis ; and is continuous with
the hemisphere. Internally, it forms the lateral boundary of the third ventricle ;
and running along its upper border is seen the peduncle of the pineal gland. Its
upper surface is free, being pa#ly seen in the lateral ventricle ; it is partly covered
by the fornix, and marked in front by an eminence, the anterior tubercle. Its
under surface forms the roof of the descending cornu of the lateral ventricle ; into
it the crus cerebri passes. Its posterior and inferior part, which projects into the
descending horn of the lateral ventricle, presents two small round eminences, the
internal and external geniculate bodies. Its anterior extremity, which is narrow,
forms the posterior boundary of the foramen of Monro.
Fig. 269.— The Third and Fourth Ventricles.
The third ventricle is the narrow oblong fissure placed between the thalami
optici, and extending to the base of the brain. It is bounded, above, by the under
surface of the velum interpositum, from which are suspended the choroid plexuses
of the third ventricle ; and, laterally, by two white tracts, one on either side, the
peduncles of the pineal gland. Its floor, somewhat oblique in its direction, is
formed, from before backwards, by the parts which close the interpeduncular space,
viz., the iamma cinerea, the tuber cinereum and infundibulum, the corpora albicantia,
and the locus perforatus ; its sides, by the optic thalami ; in front, by the anterior
528 NERVOUS SYSTEM.
crura of the fornix, and part of the anterior commissure ; behind, by the posterior
commissure, and the iter e tertio ad quartum venlriculum.
The cavity of the third ventricle is crossed by three commissures, named, from
their position, anterior, middle, and posterior.
The anterior commissure is a rounded cord of white fibres, placed in front of the
anterior crura of the fornix. It perforates the corpus striatum on either side, and
spreads out into the substance of the hemispheres, over the roof of the descending
horn of each lateral ventricle.
The middle or soft commissure consists almost entirely of gray matter. It
connects together the thalami optici. and is continuous with the gray matter lining
the anterior part of the third ventricle.
The posterior commissure, smaller than the anterior, is a flattened white band of
fibres, connecting together the two thalami optici posteriorly. It bounds the third
ventricle posteriorly, and is placed in front of and beneath the pineal gland, above
the opening leading to the fourth ventricle.
The third ventricle has four openings connected with it. In front are two oval
apertures, one on either side, the foramina of Monro, through which the third
communicates with the lateral ventricles. Behind, is a third opening leading into
the fourth ventricle by a canal, the aqueduct of Sylvius or iter e tertio ad quartum
ventriculum. The fourth, situated in the anterior part of the floor of the ventricle,
is a deep pit, which leads downwards to the funnel-shaped cavity of the infundi-
bulum, the iter ad infundibulum.
The lining membrane of the lateral ventricles is continued through the foramina
of Monro into the third ventricle, and extends along the iter a tertio into the
fourth ventricle ; at the bottom of the iter ad infundibulum, it ends in a cul-
de-sac.
Gray matter of the third ventricle. A layer of gray matter covers the greater
part of the surface of the third ventricle. In the floor of this cavity it exists in
great abundance, and is prolonged upwards on the sides of the thalami, extending
across the cavity as the soft commissure ; below, it enters into the corpora albi-
cantia, and surrounds in part the anterior pillars of the fornix.
Behind the third ventricle, and in front of the cerebellum, are the corpora
quadrigemina ; and resting upon these, the pineal gland.
The jmieal gland, so named from its peculiar shape (pinus, the fruit of the fir),
called also the conarium, is a small reddish-gray body, conical in form, placed
immediately behind the posterior commissure, and between the nates, upon which
it rests. It is retained in its position by a duplicature of pia mater, derived from
the under surface of the velum interpositum, which almost completely invests it.
The pineal gland is about four lines in length, and from two to three in width at
its base, and is said to be larger in the child than in the adult, and in the female
than in the male. Its base is connected with the cerebrum by some transverse
commissural fibres, derived from the posterior commissure ; and by four slender
peduncles, formed of medullary fibres. Of these, the two superior pass forwards
upon the upper and inner margin of the optic thalami to the anterior crura of the
fornix, with which they become blended. The inferior peduncles pass vertically
downwards from the base of the pineal gland, along the back part of the inner
surface of the thalami, and are only seen on a vertical section through the gland.
The pineal gland is very vascular, and consists chiefly of gray matter, with a few
medullary fibres. In its base is a small cavity, said by some to communicate with
that of the third ventricle. It contains a transparent viscid fluid, and occasionally
a quantity of sabulous matter, named acervulus 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 found
at all periods of life. When this body is solid, the sabulous matter is found upon
its surface, and occasionally upon its peduncles.
On the removal of the pineal gland and adjacent portion of pia mater, the corpora quadri-
gemina are exposed.
CORPORA QUADRIGEMINA — VALVE OF VIEUSSENS. 529
The corpora or iubercula quadrigemina — the optic lobes — are four rounded emi-
nences placed in pairs, two in front and two behind, separated from another by a
crucial depression. They are situated immediately behind the third ventricle
and posterior commissure, beneath the posterior border of the corpus callosum,
and above the iter e tertio ad quartum ventriculum. The anterior pair, the nates,
are the larger, oblong from before backwards, and of a gray color. The posterior
pair, the testes, are hemispherical in form, and lighter in color than the preceding.
They are connected on each side with the thalamus opticus, and commencement
of the optic tracts, by means of two white prominent bands, termed brachia. Those
connecting the nates with the thalamus {brachia anteriora) are the larger, and pass
obliquely outwards. Those connecting the testes with the thalamus are called the
brachia posteriora. Both pairs, in the adult, are quite solid, being composed of white
matter externally, and gray matter within. These bodies are larger in the lower,
animals than in man. In fishes, reptiles, and birds, they are only two in number,
are called the optic lobes, from their connection with the optic nerves, and are
hollow in their interior ; but in mammalia, they are four in number, as in man, and
quite solid. In the human foetus, they are developed at a very early period, and
form a large proportion of the cerebral mass ; at first, they are only two in number,
as in the lower mammalia, and hollow in their interior.
These bodies, from below, receive white fibres from the olivary fasciculus or fillet;
they are also connected with the cerebellum, by means of a large white cord on
each side, the processus ad testes or superior peduncles of the cerebellum, which
pass up to the thalami from the tubercula quadrigemina.
The valve of Vieussens is a thin translucent lamina of medullary substance,
stretched between the two processus e cerebello ad testes ; it covers in the canal
leading from the third to the fourth ventricle, forming part of the roof of the latter
cavity. It is narrow in front, where it is connected with the testes ; and broader
behind, at its connection with the vermiform process of the cerebellum. A slight
elevated ridge, the frenulum, descends upon the upper part of the valve from the
corpora quadrigemina, and on either side of it may be seen the fibres of origin of
the fourth nerve. Its lower half is covered by a thin transversely grooved lobule
of gray matter prolonged from the anterior border of the cerebellum ; this is called
the linguetta laminosa.
The corpora geniculata are two small, flattened, oblong masses, placed on the
outer side of the corpora quadrigemina, and on the under and back part of each
optic thalamus, and named, from their position, corpus geniculatum externum and
corpus geniculatum internum. They are placed one on the outer and one on the
inner side of each optic tract. In this situation, the optic tract may be seen
dividing into two bands, one of which is connected with the external geniculate body
and nates, the other being connected with the internal geniculate body and testis.
Structure of the cerebrum. The white matter of each hemisphere consists of
three kinds of fibres. 1. Diverging or peduncular fibres, which connect the
hemisphere with the cord and medulla oblongata. 2. Transverse commissural
fibres which connect together the two hemispheres. 3. Longitudinal commissural
fibres, which connect distant parts of the same hemisphere.
The diverging or peduncular fibres consist of a main body, and of certain accessory
fibres. The main body of fibres originates in the columns of the cord and medulla
oblongata, and enters the cerebrum through the crus cerebri, where they are
arranged in two bundles, separated by the locus niger. Those fibres which form
the inferior or fasciculated portion of the crus are derived from the anterior
pyramid, and, ascending, pass mainly through the centre of the striated body ; those
on the opposite surface of the crus, which form the tegmentum, are derived from
the posterior pyramid and fasciculi teretes ; ascending, they pass, some through the
under part of the thalamus, and others through both thalamus and corpus striatum,
decussating in these bodies with each other, and with the fibres of the corpus
callosum. The optic thalami also receive accessory fibres from the jwocessus ad
testes, the olivary fasciculus, the corpora quadrigemina, and corpora geniculata
34
530 NERVOUS SYSTEM.
Some of the diverging fibres end in the cerebral ganglia, whilst others pass
through and receive additional fibres from them, and, as they emerge, radiate into
the anterior, middle, and posterior lobes of the hemisphere, decussating again with
the fibres of the corpus cailosum, before passing to the convolutions.
The transverse commissural fibres connect together the two hemispheres across
the middle line. They are formed by the corpus cailosum, and the anterior and
posterior commissures.
The longitudinal commissural fibres connect together distant parts of the same
hemisphere, the fibres being disposed in a longitudinal direction. They form the
fornix, the taenia semicircularis, and peduncles of the pineal gland, the stria?
longitudinales, the fibres of the gyrus fornicatus, and the fasciculus uncinatus.
CEREBELLUM.
The Cerebellum or little brain is that portion of the encephalon which is con-
tained in the inferior occipital fossee. It is situated beneath the posterior lobes
of the cerebrum, from which it is separated by the tentorium. Its average weight
in the male is 5 oz. 4 drs. It attains its maximum weight between the twenty-fifth
and fortieth 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 cerebrum is, in the male, as 1 to 8$ ; and, in the female, as 1 to 8 J. In the
infant, it is proportionally much smaller than in the adult, the relation between
them being, according to Chaussier, between 1 to 13 and 1 to 26 ; by Cruveilhier
it was found to be 1 to 20. In form, the cerebellum is oblong, flattened from
above downwards, its greatest diameter being from side to side. It measures
from three and a half to four inches transversely, from two to two and a half
inches from before backwards, being about two inches thick in the centre, and
about six lines at its circumference, the thinnest part. It consists of gray and
white matter : the former, darker than that of the cerebrum, occupies the surface ;
the latter, the interior. The surface of the cerebellum is not convoluted like the
cerebrutr^but traversed by numerous curved furrows or sulci, which vary in depth
at different parts, and correspond to the intervals between the laminae of which its
exterior is composed.
Its upper surface (fig. 270) is somewhat elevated in the median line, and de-
Upper Surface of the Cerebellum.
[tressed towards its circumference; it consists of two lateral hemispheres, connected
together by an elevated median portion or lobe, the superior vermiform process.
CEREBELLUM.
531
The median lobe is the fundamental part, and in some animals, as fishes and reptiles,
the only part which exists ; the hemispheres being additions, and attaining their
maximum in man. The hemispheres are separated, in front, by a deep notch, the
incisura cerebelli anterior, which encircles the corpora quadrigemina behind ; they
are also separated by a similar notch behind, the incisura cerebelli posterior, in
which is received the upper part of the falx cerebelli. The superior vermiform
process (upper part of the median lobe of the cerebellum), extends from the notch
on the anterior to that on the posterior border. It is divided into three lobes : the
lobulus centralis, a small lobe, situated in the incisura anterior ; the monticulus cere-
belli, the central projecting part of the process; and the commissura simplex, a
small lobe near the incisura posterior.
The under surface of the cerebellum (fig. 271) is subdivided into two lateral
hemispheres by a depression, the valley, which extends from before backwards in
the middle line. The lateral hemispheres are lodged in the inferior occipital fossae ;
the median depression, or valley, receives the back part of the medulla oblongata,
is broader in the centre than at either extremity, and has, projecting from its floor,
part of the median lobe of the cerebellum, called the inferior vermiform process.
The parts entering into the composition of this body are, from behind forwards, the
Fig. 271. — Under Surface of che Cerebellum.
commissura brevis, situated in the incisura posterior ; in front of this, a laminated
conical projection, the pyramid; more anterior, is a larger eminence, the uvula,
placed between the two rounded lobes which occupy the sides of the valley, the
amygdalae, and connected with them by a commissure of gray matter, indented
on the surface, called the furrowed band. In front of the uvula is the nodule;
it is the anterior pointed termination of the inferior vermiform process, and projects
into the cavity of the fourth ventricle; it has been named by Malacarne the
laminated tubercle. On each side of the nodule is a thin layer of white substance,
attached externally to the flocculus, and internally to the nodule, and to a corre-
sponding part on the opposite side ; they form together the posterior medullary
velum or commissure of the flocculus. It is usually covered in and concealed by
the amygdalae, and cannot be seen until these are drawn aside. This band is
of a semilunar form on each side, its anterior margin being free and concave, its
posterior being attached just in front of the furrowed band. Between it and the
nodulus and uvula behind, is a deep fossa, called the swallow's nest {nidus hirun-
dinis).
Lobes of the cerebellum. Each hemisphere is divided into an upper and a lower
portion by the great horizontal fissure, which commences in front at the pons, and
passes horizontally round the free margin of either hemisphere, backwards to the
middle line. From this primary fissure numerous secondary fissures proceed, which
separate the cerebellum into lobes.
532 NERVOUS SYSTEM.
Upon the upper surface of either hemisphere there are two lobes, separated from
each other by a fissure. These are the anterior or square lobe, which extends
as far back as the posterior edge of the vermiform process, and the posterior or
semilunar lobe, which passes from the termination of the preceding to the great
horizontal fissure.
Upon the under surface of either hemisphere there are five lobes, separated by
sulci ; these may be described from before backwards. The flocculus or sub-pedun-
cular lobe is a prominent tuft, situated behind and below the middle peduncle of the
cerebellum ; its surface is composed of gray matter, subdivided into a few small
laminae ; it is sometimes called the pneumo gastric lobule, from being situated be-
hind the pneumogastric nerve. The amygdala or tonsil is situated on either side
of the great median fissure or valley, and projects into the fourth ventricle. The
digastric lobe is situated on the outside of the tonsil, being connected in part with
the pyramid. Behind the digastric is the slender lobe, which is connected with
the back part of the pyramid and the commissura brevis ; and more posteriorly
is the inferior posterior lobe, which also joins the commissura brevis in the valley.
Fourth Ventricle.
The fourth ventricle or ventricle of the cerebellum is the space between the pos-
terior surface of the medulla oblongata and pons in front, and the cerebellum
behind. It is lozenge-shaped, being contracted above and below, and broadest
across its central part. It is bounded laterally by the processus e cerebello ad testes
above, and by the diverging posterior pyramids and restiform bodies below.
The roof is arched; it is formed by the valve of Vieussens and the under surface
of the cerebellum, which presents in this situation four small eminences or lobules,
two occupying the median line, the nodulus and uvula, the remaining two, the
amygdalae, being placed on either side of the uvula
The anterior boundary or floor is formed by the posterior surface of the medulla
oblongata and pons. In the median line is seen the posterior median fissure ; it
becomes gradually obliterated above, and terminates below in the point of the
calamus scriptorius, formed by the convergence of the posterior pyramids. At this
point is the orifice of a short canal terminating in a cul-de-sac, the remains of the
canal which extends in fcetal life through the centre of the cord: On each side
of the median fissure are two slightly convex longitudinal eminences, the fasciculi
teretes ; they extend the entire length of the floor, being indistinct below, and of
a grayish color, but well marked and whitish above. Each eminence consists of
fibres derived from the lateral tract and restiform body, which ascend to the cere-
brum. Opposite the crus cerebelli, on the outer side of the fasciculi teretes, is a
small eminence of dark gray substance, which presents a bluish tint through the
thin stratum covering it ; this is called the locus cceruleus; and a thin streak of the
same color continued up from this on either side of the fasciculi teretes, as far as
the top of the ventricle, is called the taenia violacea. The lower part of the floor
of the ventricle is crossed by several white transverse lines, linese transversa ; they
emerge from the posterior median fissure ; some enter the crus cerebelli, others
enter the roots of origin of the auditory nerve, whilst some pass upwards and
outwards on the floor of the ventricle.
The lining membrane of the fourth ventricle is continuous with that of the
third, through the aqueduct of Sylvius, and its cavity communicates below with
the sub-arachnoid space of the brain and cord through an aperture in the layer of
pia mater, extending between the cerebellum and medulla oblongata. Laterally,
this membrane is reflected outwards a short distance between the cerebellum and
medulla.
The choroid plexuses of the fourth ventricle are two in number ; they are
delicate vascular fringes, which project into the ventricle on each side, passing
from the point of the inferior vermiform process to the outer margin of the resti-
form bodies.
STRUCTURE OF CEREBELLUM.
533
The gray matter in the floor of the ventricle consists of a tolerably thick
stratum, continuous below with the gray commissure of the cord, and extending
up as high as the aqueduct of Sylvius, besides some special deposits connected
with the roots of origin of certain nerves. In the upper half of the ventricle is
a projection situated over the nucleus, from which the sixth and facial nerves
take a common origin. In the lower half are three eminences on each side for
the roots of origin of the eighth and ninth nerves.
Structure. If a vertical section is made through either hemisphere of the cere-
bellum, midway between
its centre and the superior Fig. 272.— Vertical Section of the Cerebellum,
vermiform process ; it will
be found to consist of a
central stem of white mat-
ter, which contains in its
interior a dentate body.
From the surface of each
hemisphere, a series of
plates of medullary matter
are detached, which, co-
vered with gray matter,
form the laminae ; and from
its anterior part arise three
large processes or pedun-
cles, superior, middle, and
inferior, by which it is con-
nected with the rest of the
encephalon.
The laminae are about
ten or twelve in number, including those on both surfaces of the cerebellum, those
in front being detached at a right angle, and those behind at an acute angle ; as
each lamina proceeds outwards, other secondary laminae are detached from it, and,
from these, tertiary laminae. The arrangement thus described gives to the cut
surface of the organ a foliated appearance, to which the name arbor vitse has been
given. Each lamina consists of white matter, covered externally by a layer of
gray substance.
The white matter of each lamina is derived partly from the central stem ; in
addition to which white fibres pass from one lamina to another.
The gray matter resembles somewhat the cortical substance of the convolutions.
It consists of two layers, the external one, soft and of a grayish color, the internal
one, firmer and of a rust color.
The corpus dentatum. or ganglion of the cerebellum is situated a little to the inner
side of the centre of the stem of white matter. It consists of an open bag or
capsule of gray matter, the section of which presents a gray dentated outline,
being open at its anterior part. It is surrounded by white fibres ; white fibres
are also contained in its interior, which issue from it to join the superior peduncles.
The peduncles of the cerebellum, superior, middle, and inferior, serve to connect
it with the rest of the encephalon.
The superior peduncles (processus e cerebello ad testes) connect the cerebellum with
the cerebrum ; they pass forwards and upwards to the testes, beneath which they
ascend to the crura cerebri and optic thalami, forming part of the diverging cere-
bral fibres ; each peduncle forms part of the lateral boundary of the fourth
ventricle, and is connected with its fellow of the opposite side by the valve of
Vieussens. The peduncles are continuous behind with the folia of the inferior
vermiform process, and with the white fibres in the interior of the corpus den-
tatum. Beneath the corpora quadrigemina. the innermost fibres of each peduncle
decussate with each other, so that some fibres from the right half of the cerebellum
are continued to the left half of the cerebrum.
534 NERVOUS SYSTEM.
The inferior peduncles (processus admedullam) connect the cerebellum with the
medulla oblongata. They pass downwards to the back part of the medulla, and
form part of the restiform bodies. Above, the fibres of each process are con-
nected chiefly with the laminae, on the upper surface of the cerebellum; and
below, they are connected with all three tracts of one half of the medulla, and,
through these, with the corresponding half of the cord, excepting the posterior
median columns.
The middle peduncles (processiLS ad pontem), the largest of the three, connect
together the two hemispheres of the cerebellum, forming their great transverse
commissure. They consist of a mass of curved fibres, which arise in the lateral
parts of the cerebellum, and pass across to the same points on the opposite side.
They form the transverse fibres of the pons Yarolii.
On the General Anatomy of the Nerves and Nervous Centres, the student may consult the
works of Kblliker, and Todd and Bowman, before alluded to ; and the Articles " Nerve and Nerv-
ous Centres," in the Cyclop, of Anat. and Physiol. — For further information on the Descriptive
Anatomy of the Nervous Centres, consult: — Cruveilhier's " Anatomie Descriptive ;" Todd's
" Descriptive Anatomy of the Brain, Spinal Cord, and Ganglions ;" Herbert Mayo's " Plates of
the Brain and Spinal Cord;" and Arnold's " Tabulae Anatomical. Fascic. i. Icones Cerebri et
Medullar Spinalis."
Cranial Nerves.
The Cranial Nerves, nine in number on each side, include those nerves which
arise from some part of the cerebro-spinal centre, and are transmitted through
foramina in the base of the cranium. They have been named numerically,
according to the order in which they pass out of this cavity. Their names are
also derived from the part to which each is distributed, or from the special
function appropriated to each. Taken in their order, from before backwards,
they are as follows : —
1st. Olfactory. ,_ , ( Facial or Portio dura.
2d. Optic. ' \ Auditory or Portio mollis.
3d. Motor oculi. I Glosso-pharyngeal.
4th. Pathetic. 8th. < Pneumogastric or Par vagum.
5th. Trifacial or Trigemini. ( Spinal accessory.
6th. Abducens. 9th. Hypoglossal.
If, however, the 7th pair be considered as two, and the 8th pair as three distinct
nerves, then their number will be increased to twelve, which is the arrangement
adopted by Sommering.
The cranial nerves may be subdivided into four groups, according to the
peculiar function possessed by each, viz., nerves of special sense; nerves of
common sensation ; nerves of motion ; and mixed nerves. These groups may
be thus arranged : —
1. Nerves of Special Sense. 2. Nerves of Motion.
Olfactory. Motor oculi-
Optic Pathetic.
Auditorv Part of third division of fifth (de-
Part of giosso-pharyngeal (described scr^ under the fifth nerve,
under the eighth pair, p. 555). P' 5 °)* '
Lingual branch of the fifth (described Abducens.
under the fifth nerve, p. 550). facial.
Hypoglossal.
4. Mixed Nerves.
3. Nerves of Common Sensation. Pneumogastric _ (described under
the eighth pair, p. 557).
Fifth (greater portion). Spinal accessory (described under
Part oi glosso-pharyngeal. the eighth pair, p. 560).
All the cranial nerves are connected to some part of the surface of the brain.
This is termed their superficial or apparent origin. But their fibres may, in all
cases, be traced deeply into the substance of the organ. This would form their
deep or real origin.
1. Nerves o» Special Sense.
Olfactory Nerve.
The First or Olfactory Nerve, the special nerve of the sense of smell, may
be regarded as a portion of the cerebral substance, pushed forwards in direct
relation with the organ to which it is distributed. It arises by three roots.
The external or long root is a narrow white medullary band, which passes
outwards across the fissure of Sylvius, into the substance of the middle lobe of the
cerebrum. Its deep origin may be traced to the corpus striatum1, the superficial
fibres of the optic thalamus2, the anterior commissure3, and the convolutions of
the island of Eeil.
1 Vicussens, Winslow, Monro, Mayo. a Valentin. « Cruveilhier.
535
536
CRANIAL NERVES.
The middle or gray root arises from a papilla of gray matter, the caruncula
mammillaris, imbedded in the anterior lobe. This root is prolonged into the
nerve from the adjacent part of the brain, and contains white fibres in its interior,
which are connected with the corpus striatum.
The internal or short root is composed of white fibres, which arise from the
inner and back part of the anterior lobe, being connected, according to Foville,
with the longitudinal fibres of the gyrus fornicatus.
These three roots unite, and form a flat band, narrower in the middle than at
either extremity, and its section of a somewhat prismoid form. It is soft in texture,
and contains a considerable amount of gray matter in its substance. As it passes
forwards, it is contained in a deep sulcus, between two convolutions, lying on the
under surface of the anterior lobe, on either side of the longitudinal fissure, and
is retained in position by the arachnoid membrane which covers it. On reaching
the cribriform plate of the ethmoid bone, it expands into an oblong mass of grayish-
white substance, the olfactory bulb. From the under part of this bulb are given
off numerous filaments, about twenty in number, which pass through the cribriform
foramina, and are distributed to the mucous membrane of the nose. Each filament
is surrounded by a tubular prolongation from the dura mater and pia mater; the
former being lost on the periosteum lining the nose ; the latter, in the neurilemma
of the nerve. The filaments, as they enter the nares, are divisible into three
groups : an inner group, larger than those on the outer Avail, spread out over the
upper third of the septum ; a middle set, confined to the roof of the nose ; and
an outer set, which are distributed over the superior and middle turbinated bones,
and the surface of the ethmoid in front of them. As the filaments descend, they
unite in a plexiform network, and become gradually lost in the lining membrane.
Their mode of termination is unknown.
The olfactory differs in structure from other nerves, in containing gray matter
in its interior, and being soft and pulpy in structure. Its filaments are deficient
in the white substance of Schwann, are not divisible into fibrillae, and resemble
the gelatinous fibres in being nucleated, and of a finely-granular texture.
Fig. 273.— The Optic Nerves and Optic Tracts.
Optic Nerve.
The Second or Optic Nerve, the special nerve of the sense of sight, is
distributed exclusively to the eyeball. The nerves of opposite sides are connected
together at the commissure ; and from the back of the commissure, they may be
traced to the brain, under the name of the
optic tracts.
The optic tract, at its connection with
the brain, divides into two bands which
are continued into the optic thalami, the
corpora geniculata, and the corpora
quadrigemina. The fibres of origin from
the thalamus may be traced partly from
its surface, and partly from its interior.
From this origin, the tract winds obliquely
across the under surface of the crus cerebri,
in the form of a flattened band, destitute
of neurilemma, and is attached to the crus
by its anterior margin. It now assumes a
cylindrical form, and, as it passes forwards,
is connected with the tuber cinereum, and
lamina cinerea, from both of which it
receives fibres. According to Foville, it
is also connected with the taenia semi-
circularis, and the anterior termination of the gyrus fornicatus. It finally joins
with the nerve of the opposite side, to form the optic commissure.
OPTIC — AUDITORY — MOTOR OCULI. 537
The commissure, somewhat quadrilateral in form, rests upon the olivary process
of the sphenoid bone, being bounded, in front, by .the lamina cinerea; behind, by
the tuber cinereum ; on either side, by the anterior perforated space. Within
the commissure, the optic nerves of the two sides undergo a partial decussation.
The fibres which form the inner margin of each tract,
are continued across from one to the other side of the ^f^^SJLS^
brain, and have no connection with the optic nerves.
These may be regarded as commissural fibres (inter-
cerebral) between the thalami of opposite sides.
Some fibres are continued across the anterior border
of the chiasma, and connect the optic nerves of the
two sides, having no relation with the optic tracts. "^ •/w"'*— *•
They may be regarded as commissural fibres between the two retinas (inter-retinal
fibres). The outer fibres of each tract are continued into the optic nerve of the same
side. The central fibres of each tract are continued into the optic nerve of the
opposite side, decussating in the commissure with similar fibres of the opposite tract.1
The optic nerves arise from the fore part of the commissure, and, diverging from
one another, become rounded in form, firm in texture, and are inclosed in a sheath
derived from the arachnoid. As each nerve passes through the corresponding
optic foramen, it receives a sheath from the dura mater ; and as it enters the,orbit,
this sheath subdivides into two layers, one of which becomes continuous with the
periosteum of the orbit ; the other forms a sheath for the nerve, and surrounds it
as far as the sclerotic. The nerve passes through the cavity of the orbit, pierces
the sclerotic and choroid coats at the back part of the eyeball, a little to the nasal
side of its centre, and expands into the retina. A small artery, the arteria cen-
tralis retinas, perforates the optic nerve a little behind the globe, and runs along
its interior in a tubular canal of fibrous tissue. It supplies the inner surface of
the retina, and is accompanied by corresponding veins.
Auditory Nerve.
The Auditory Nerve, the portio mollis of the seventh pair, is the special nerve
of the sense of hearing, being distributed exclusively to the internal ear. The
portio dura of the seventh pair, the facial nerve, is the motor nerve of the muscles
of the face. It will be described with the motor cranial nerves.
The auditory nerve arises from numerous white striae, the lineae transversae,
which emerge from the posterior median fissure in the anterior wall, or floor, of
the fourth ventricle. It is also connected with the gray matter of the medulla,
which corresponds to the locus caeruleus. According to Foville, the roots of this
nerve are connected, on the under surface of the middle peduncle, with the gray
substance of the cerebellum, with the flocculus, and with the gray matter at the
borders of the calamus scriptorius. The nerve winds round the restiform body,
from which it receives fibres, and passes forwards across the posterior border of
the eras cerebelli, in company with the facial nerve, from which it is partially
separated by a small artery. It then enters the meatus auditorius, in company
with the facial nerve, and, at the bottom of the meatus, divides into two branches,
cochlear and vestibular, which are distributed, the former to the cochlea, the
latter to the vestibule and semicircular canals. The auditory nerve is very soft
in texture (hence the name portio mollis), destitute of neurilemma, and, within the
meatus, receives one or two filaments from the facial.
2. The Motor Cranial Nerves.
Third or Motor Oculi Nerve.
The Third or Motor Oculi Nerve supplies all the muscles of the eyeball, except
the Superior oblique and External rectus ; it also sends motor filaments to the iris.
1 A specimen of congenital absence of the optic commissure is to be found in the Museum of
the Westminster Hospital.
538
CRANIAL NERVES.
£ j la.TroelileqgX.
It is a rather large nerve, of rounded form and firm texture, having its apparent
origin from the inner surface of the crus cerebri, immediately in front of the pons
Varolii.
The deep origin may be traced into the substance of the crus, where some of
its fibres are connected with the locus niger ; others run downwards, among the
longitudinal fibres of the pons, whilst others ascend, to be connected with the
tubercula quadrigemina and valve of Vieussens. According to Stilling, the
fibres of the nerve pierce the peduncle and locus niger, and arise from a gray
nucleus in the floor of the aqueduct of Sylvius. On emerging from the brain, it
is invested in a sheath of pia mater, and inclosed in a prolongation from the
arachnoid. It then pierces the dura mater on the outer side of the anterior
clinoid process, where its serous covering is reflected from it, and passes along
the outer wall of the cavernous sinus, above the other orbital nerves, receiving
in its course one or two filaments from the cavernous plexus of the sympathetic.
It then divides into two branches, which enter the orbit through the sphenoidal
fissure, between the two
Fig. 275.— Nerves of the Orbit. Seen from above. heads of the External rec-
tus muscle. On passing
through the fissure, the
nerve is placed below the
fourth, and the frontal and
lachrymal branches of the
ophthalmic nerve.
The superior division,
the smaller, passes inwards
across the optic nerve, and
supplies the Superior rectus
and Levator palpebral.
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 largest of the
three, passes forwards, be-
tween the Inferior and Ex-
ternal recti, to the Inferior
oblique. From the latter, a
short, thick branch is given
off to the lower part of the
lenticular ganglion, forming
its inferior root, as well as
two filaments to the Inferior
rectus. All these branches
enter the muscles on their
ocular surface.
(Hi 'current Filamrni
I U Aura-JIattr
Fourth Nerve.
The Fourth or Trochlear nerve, the smallest of the cranial nerves, supplies
the Superior oblique muscle. It arises from the upper part of the valve of
Vieussens, immediately behind the testis, and divides, beneath the corpora quadri-
gemina, into two fasciculi ; the anterior one arising from a nucleus of gray matter,
close to the middle line of the floor of the Sylvian aqueduct ; the posterior one
from a gray nucleus, at the upper part of the floor of the fourth ventricle, close to
the origin of the fifth nerve. The two nerves are connected together, at their
FOURTH— SIXTH.
539
origin, by a transverse band of white fibres, which crosses the surface of the velum.
The nerve winds round the outer side of the crus cerebri, immediately above the
pons Varolii, pierces the dura mater in the free border of the tentorium cerebelli,
near the posterior clinoid process, above the oval opening for the fifth nerve, and
passes forwards through the outer wall of the cavernous sinus, below the third ;
but, as it enters the orbit, through the sphenoidal fissure, it becomes the highest of
all the nerves. In the orbit, it passes inwards, above the origin of the Levator
palpebrae, and finally enters the orbital surface of the Superior oblique muscle.
In the outer wall of the cavernous sinus, this nerve receives some filaments
from the carotid plexus of the sympathetic. It is not unfrequently blended with
the ophthalmic division of the fifth ; and occasionally gives off' a branch to assist
in the formation of the lachrymal nerve. It also gives off a recurrent branch,
which passes backwards 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.
Fig. 276. — Nerves of the Orbit and Ophthalmic Ganglion. Side view.
Internal Cavatid As.
h Carotid Plaits.
Hot/)*
Hoot
Sixth or Abducens Nerve.
The Sixth or Abducens Nerve supplies the External rectus muscle. Its
apparent origin is by several filaments from the constricted part of the corpu3
pyramidale, close to the pons, or from the lower border of the pons itself.
The deep origin of this nerve has been traced by Mayo, between the fasciculi
of the corpus pyramidale, to the posterior part of the medulla, where Stilling
has shown its connection with a gray nucleus in the floor of the fourth ventricle.
The nerve pierces the dura mater, immediately below the posterior clinoid pro-
cess, lying in a groove by the side of the body of the sphenoid bone. It passes
forwards through the cavernous sinus, lying on the outer side of the internal
carotid artery, where it is joined by several filaments from the carotid plexus, by
one from Meckel's ganglion (Bock), and another from the ophthalmic nerve. It
enters the orbit through the sphenoidal fissure, and lies above the ophthalmic
vein, from which it is separated by a lamina of dura rnater. It then passes
between the two heads of the External rectus, and is distributed to that muscle
on its ocular surface.
Relations of the Orbital Nerves.
The above-mentioned nerves, as well as the ophthalmic division of the fifth, as
they pass to the orbit, bear a certain relation to each other in the cavernous
540 CRANIAL NERVES.
sinus, at the sphenoidal fissure, and in the cavity of the orbit, which will be now
described.
In the cavernous sinus, the third, fourth, and ophthalmic division of the fifth.
are placed in the dura mater, forming the outer wall of the sinus in numerical
order, both from above downwards, and from within outwards. The sixth nerve
lies at the outer side of the internal carotid artery. As these nerves pass forwards
to the sphenoidal fissure, the third and fifth nerves become divided ; and the sixth
approaches the rest ; so that their relative position becomes considerably changed.
In the sphenoidal fissure, the fourth, and the frontal and lachrymal divisions
of the ophthalmic, 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.
The superior division of the third is the highest ; beneath this, the nasal branch
of the fifth ; then the inferior division of the third ; and the sixth lowest of all.
In the orbit, the fourth, and the frontal and lachrymal divisions of the ophthalmic,
lie on the same plane immediately beneath the periosteum, the fourth nerve being
internal and resting on the Superior oblique, the frontal resting on the Levator
palpebral, and the lachrymal on the External rectus. Next in order comes the
superior division of the third nerve lying immediately beneath the Superior rectus,
and then the nasal division of the fifth crossing the optic nerve from the outer to
the inner side of this cavity. Beneath these is found the optic nerve, surrounded
in front by the ciliary nerves, and having the lenticular ganglion on its outer
side, between it and the External rectus. Below the optic is the inferior division
of the third, and the sixth, which lies on the outer side of the cavity.
Facial Nerve.
The Facial Nerve, the portio dura of the seventh pair, is the motor nerve of
all the muscles of the face, the Platysma and Buccinator. It supplies also the
muscles of the external ear, the posterior belly of the Digastric and the Stylo-hyoid.
Through the chorda tympani it supplies the Lingualis ; by its tympanic branch,
the Stapedius and Laxator tympani; through the otic ganglion, the Tensor tympani ;
and through the connection of its trunk with the Vidian nerve, by the petrosal
nerves, it probably supplies the Levator palati and Azygos uvulas. It arises from
the lateral tract of the medulla oblongata, in the groove between the olivary and
restiform bodies. Its deep origin may be traced to the floor of the fourth ventricle,
where it is connected with the same nucleus as the sixth nerve. This nerve is
situated a little nearer to the middle line than the portio mollis, close to the lower
border of the pons Varolii, from which some of its fibres are derived.
Connected with this nerve, and lying between it and the portio mollis, is a small
fasciculus, the portio inter duram et mollem of Wrisberg. This accessory portion
arises from the lateral column of the cord.
The nerve passes forwards and outwards upon the crus cerebelli, and enters the
internal auditory meatus with
Fig. 277.— The Course and Connections of the Facial the auditory nerve. Within
Nerve in the Temporal Bone. the meatus> the faeial nerve
tttv^ Jf. .T> lies first to the inner side of
***** Mr—i l^L^^r^^^^Sli^ tne auditory, and then in a
*«y'^Z^%f^SB|^OirmA groove upon this nerve, and is
intumescnu* Ca"^-"'-'^^^^^\T»'i connected to it by one or two
juj.r f '-««Kl8f^^R'l At tllc bottom of the mea-
• ■ {Audit™, ^^ijJwjm J.j tus, it enters the aquasductus
^^ Fallopii, and follows the ser-
pentine course of that canal
through the petrous portion
of the temporal bone, from its commencement at the internal meatus to its termina-
tion at the stylo-mastoid foramen. It is at first directed outwards towards the
FACIAL.
541
hiatus Fallopii, where it forms a reddish gangliform swelling (intumescentia
gangliformis), and is joined by several nerves ; bending suddenly backwards, it
runs in the internal wall of the tympanum, above the fenestra ovalis, and
at the back of this cavity passes vertically downwards to the stylo-mastoid
foramen.
On emerging from this aperture, it runs forwards 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.
The communications of the facial nerve may be thus arranged : —
In the internal auditory meatus
In the aquaeductus Fallopii
At its exit from the stylo-mastoid
foramen .
On the face
With the auditory nerve.
With Meckel's ganglion by the large
petrosal nerve.
With the otic ganglion by the small
petrosal nerve.
With the sympathetic on the middle me-
ningeal by the external petrosal nerve.
With the pneumogastric.
" glossopharyngeal.
" carotid plexus.
" auricularis magnus.
" auriculotemporal.
With the three divisions of the fifth.
In the internal auditory meatus, some minute filaments pass between the facial
and auditory nerves.
Opposite the hiatus Fallopii, the gangliform enlargement on the facial nerve
communicates, by means of the large petrosal nerve, with Meckel's ganglion,
forming its motor root ; by a filament from the small petrosal with the otic
ganglion ; and by the external petrosal, with the sympathetic filaments accom-
panying the middle meningeal artery (Bidder). From the gangliform enlarge-
ment, according to Arnold, a twig is sent back to the auditory nerve.
At its exit from the stylo-mastoid foramen, it sends a twig to the pneumogastric,
another to the glossopharyngeal nerve, and communicates with the carotid plexus
of the sympathetic, with the great auricular branch of the cervical plexus, with
the auriculo-temporal branch of the inferior maxillary nerve in the parotid gland,
and on the face with the terminal branches of the three divisions of the fifth.
Branches of Distribution.
Within aquaeductus Fallopii
At exit from stylo-mastoid
foramen
On the face
Tympanic.
Chorda tympani.
Posterior auricular.
Digastric.
Stylo-hyoid.
( Temporal.
Temporo-facial < Malar.
( Infra-orbital.
( Buccal.
■! Supra-maxillary.
( Infra-maxillary.
Cervico-facial
The Tympanic branch arises from the nerve opposite the pyramid; it is a small
filament, which supplies the Stapedius and Laxator tympani muscles.
542
CRANIAL NERVES.
The Chorda tympani is given off from the facial as it passes vertically down-
wards at the back of the tympanum, about a quarter of an inch before its exit
from the stylo-mastoid foramen. It ascends from below upwards in a distinct
canal, parallel with the aquaeductus Fallopii, and enters the cavity of the tym-
panum through an opening between the base of the pyramid and the attachment
of the membrana tympani, and becomes invested with mucous membrane. It
passes forwards through the cavity of the tympanum, between the handle of the
malleus and vertical ramus of the incus, to its anterior inferior angle, and emerges
from ' that cavity through a foramen (the canal of Huguier) at the inner side of
Fig. 278.— The Nerves of the Scalp, Face, and Side of the Neck.
Terminations
>f Supra - trochlear
tf Infra -trochlea*
cf Nasal
the Glaserian fissure. It then descends between the two Pterygoid muscles, and
meets the gustatory nerve at an acute angle, after communicating with which, it
accompanies it to the submaxillary gland ; it then joins the submaxillary ganglion,
and terminates in the Lingualis muscle.
The Posterior auricular nerve arises close to the stylo-mastoid foramen, and
passes upwards- in front of the mastoid process, where it is joined by a filament
FACIAL. 543
from the auricular branch of the pneumogastric, and communicates with the deep
branch of the auricularis magnus ; as it ascends between the meatus and mastoid
process it divides into two branches. The auricular branch supplies the Retra-
hens aurem, and the integument at the back part of the auricle. The occipital
branch, the larger, passes backwards along the superior curved line of the occi-
pital bone, and supplies the occipital portion of the Occipito-frontalis and the
integument.
The Stylo-hyoid is a long slender branch, which passes inwards, entering the
Stylo-hyoid muscle about its middle ; it communicates with the sympathetic fila-
ments on the external carotid artery.
The Digastric branch usually arises by a common trunk with the preceding ; 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.
The Temporo-facial, the larger of the two terminal branches, passes upwards
and forwards through the parotid gland, crosses 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 may be divided into three sets,
temporal, malar, and infra-orbital.
The temporal branches cross the zygoma to the temporal region, supplying
the Attrahens aurem and the integument, and join with the temporal branch of
the superior maxillary, and with the auriculo-temporal branch of the inferior
maxillary. The more anterior branches supply the frontal portion of the Occipito-
frontalis, and the Orbicularis palpebrarum muscle, joining with the supra-orbital
branch of the ophthalmic.
The malar brandies pass across the malar bone to the outer angle of the orbit,
where they supply the Orbicularis and Corrugator supercilii muscles, joining with
filaments from the lachrymal and supra-orbital nerves ; others supply the lower
eyelid, joining with filaments of the malar branches of the superior maxillary nerve.
The infra-orbital, of larger size than the rest, pass horizontally forwards 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, being distributed to the integument and hair follicles ; some
supply the lower eyelid and Pyramidalis nasi, joining, at the inner angle of the
orbit, with the infra-trochlear and nasal branches of the ophthalmic. The deep
branches pass beneath the Levator labii superioris, supply it and the Levator
anguli oris, and form a plexus (infra-orbital) by joining with the infra-orbital
branch of the superior maxillary nerve.
The Cervico-facial division of the facial nerve passes obliquely downwards
and forwards through the parotid gland, where 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, supra-maxillary, and
infra-maxillary.
The buccal branches cross the Masseter muscle, join the infra-orbital branches
of the temporo-facial division of the nerve, and with filaments of the buccal
branch of the inferior maxillary nerve. They supply the Buccinator and Orbi-
cularis oris.
The supra-maxillary branches pass forwards beneath the Platysma and De-
pressor anguli oris, supplying the muscles and the integument of the lip and chin,
anastomosing with the mental branch of the inferior dental nerve.
The infra-maxillary branches run forward beneath the Platysma, and form a
series of arches across the side of the neck over the supra-hyoid region. One of
these branches descends vertically to join with the superficial cervical nerve from
the cervical plexus ; others supply the Platysma and Levator labii inferioris.
544
CRANIAL NERVES.
Ninth or Hypoglossal Nerve.
The Ninth or Hypoglossal Nerve is the motor nerve of the tongue. It
arises by several filaments, from ten to fifteen in number, from the groove between
the pyramidal and olivary bodies, in a continuous line with the anterior roots of
the spinal nerves. According to Stilling, these roots may be traced to a gray
nucleus in the floor of the medulla oblongata, between the posterior median furrow
and the nuclei of the glossopharyngeal and vagus nerves. The filaments of this
nerve are collected into two bundles, which perforate the dura mater separately,
opposite the anterior condyloid foramen, and unite together after their passage
through it. The nerve descends almost vertically to a point corresponding with
Fig. 279. — Hypoglossal Nerve, Cervical Plexus, and their Branches.
the arTgle of the jaw. It is at first deeply seated beneath the internal carotid and
internal jugular vein, and intimately connected with the pneumogastric nerve ;
it then passes forwards between the vein and artery, and, descending the neck,
becomes superficial below the Digastric muscle. The nerve then loops round the
occipital artery, and crosses the external carotid below the tendon of the Digastric
muscle. It passes beneath the Mylo-hyoid muscle, lying between it and the
Hyoglossus, and is connected at the anterior border of the latter muscle with the
gustatory nerve ; it is then continued forwards into the Genio-hyo-glossus muscle
as far as the tip of the tongue, distributing branches to its substance.
NINTH OR HYPOGLOSSAL NERVE. 545
Branches of this nerve communicate with the
Pneumogastric. First and second cervical nerves.
Sympathetic. Gustatory.
The communication with the pneumogastric takes place close to the exit of the
nerve from the skull, numerous filaments passing between the hypoglossal and
second ganglion of the pneumogastric, or both being united so as to form one mass.
*The communication with the sympathetic takes place opposite the atlas, by
branches derived from the superior cervical ganglion, and in the same situation
it is joined by a filament with the loop connecting the first two cervical nerves.
The communication with the gustatory takes place near the anterior border of
the Hyo-glossus muscle by numerous filaments, which ascend upon it.
The branches of distribution are the
Descendens noni. Thyro-hyoid.
Muscular.
The Descendens noni is a long slender branch, which quits the hypoglossal
where it turns round the occipital artery. It descends obliquely across the sheath
of the carotid vessels, and joins just below the middle of the neck, to form a loop
with the communicating branches from the second and third cervical nerves. From
the convexity of this loop, branches pass forwards to supply the Sterno-hyoid,
Sterno-thyroid, and both bellies of the Omo-hyoid. According to Arnold, another
filament descends in front of the vessels into the chest, which joins the cardiac
and phrenic nerves. The descendens noni is occasionally contained in the sheath
of the carotid vessels, being sometimes placed over and sometimes beneath the
internal jugular vein.
The Thyro-hyoid is a small branch, arising from the hypoglossal near the pos-
terior 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 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 pass upwards into the substance of the organ.
3. Nerves of Common Sensation.
Fifth Nerve.
The Fifth Nerve [trifacial, trigeminus) is the largest cranial nerve, and resem-
bles a spinal nerve, in its origin by two roots, and in the existence of a ganglion
on its posterior root. The functions of this nerve are various. It is a nerve of
special sense, of common sensation, and of motion. It is the great sensitive nerve
of the head and face, the motor nerve of the muscles of mastication (except the
Buccinator), and its lingual branch is one of the nerves of the special sense of
taste. It arises by two roots, a posterior larger or sensory, and an anterior smaller
or motor root. Its superficial origin is from the side of the pons Varolii, a little
nearer to its upper than its lower border. The smaller root consists of three or
four bundles ; in the larger, the bundles are more numerous, 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 deep origin of the larger or sensory
root may be traced between the transverse fibres of the pons Varolii to the lateral
tract of the medulla oblongata, immediately behind the olivary body. According
to some anatomists, it is connected with the gray nucleus at the back part of the
medulla, between the fasciculi teretes and restiform columns. By others, it is
said to be continuous with the fasciculi teretes and lateral column of the cord ;
and, according to Foville, some of its fibres are connected with the transverse
fibres of the pons ; whilst others enter the cerebellum, spreading out on the sur-
face of its middle peduncle. The motor root has been traced by Bell and Retzius
to be connected with the pyramidal body. The two roots of the nerve pass for-
wards through an oval opening in the dura mater, at the apex of the petrous
35
54G CRANIAL NERVES.
portion of the temporal bone ; here the fibres of the larger root enter a large
semilunar ganglion (Casserian), while the smaller root passes beneath the ganglion
without having any connection with it, and joins outside the cranium with one
of the trunks derived from it.
The Casserian or Semilunar Ganglion is lodged in a depression near the
apex of the petrous portion of the temporal bone. It is of a somewhat crescentic
form, with its convexity turned forwards. Its upper surface is intimately adhe-
rent to the dura mater.
Branches. This ganglion receives, on its inner side, filaments from the carotid
plexus of the sympathetic ; and from it some minute branches are given off to the ten-
torium cerebelli, and the dura mater, in the middle fossa of the cranium. From
its anterior border, which is directed forwards and outwards, three large branches
proceed ; the ophthalmic, superior maxillary, and inferior maxillary. The two
first divisions of this nerve consist exclusively of fibres derived from the larger
root and ganglion, and are solely nerves of common sensation. The third or
inferior maxillary is composed of fibres from both roots. This, therefore, strictly
speaking, is the only portion of the fifth nerve which can be said to resemble a
spinal nerve.
Branches of the Fifth Nerve.
(1.) Ophthalmic Nerve.
The Ophthalmic, the first division of the fifth, is a sensory nerve. It supplies
the eyeball, the lachrymal gland, the mucous lining of the eye and nose, and the
integument and muscles of the eyebrow and forehead (fig. 275). It is the smallest
of the three divisions of the fifth, arising from the upper part of the Casserian
ganglion. It is a short, flattened band, about an inch in length, which passes for-
wards along the outer wall of the cavernous sinus, below the other nerves, and
just before entering the orbit, through the sphenoidal fissure, divides into three
branches, frontal, lachrymal, and nasal. The ophthalmic nerve is joined by fila-
ments from the cavernous plexus of the sympathetic, and gives off recurrent
filaments which pass between the layers of the tentorium, with a branch from the
fourth nerve.
Its branches are the
Lachrymal. Frontal. Nasal.
The Lachrymal is the smallest of the three branches of the ophthalmic. Not
un frequently it arises by two filaments, one from the ophthalmic, the other from
the fourth, and this, Swan considers, as the usual condition. It passes forwards
in a separate tube of dura mater, and enters the orbit through the narrowest part
of the sphenoidal fissure. In this cavity, it runs along the upper border of the
External rectus muscle, with the lachrymal artery, and is connected with the
orbital branch of the superior maxillary nerve. Within the lachrymal gland it
gives off several filaments, which supply it and the conjunctiva. Finally it pierces
the palpebral ligament, and terminates in the integument of the upper eyelid,
joining with filaments of the facial nerve.
The Frontal is the largest division of the ophthalmic, and may be regarded, both
from its size and direction, as the continuation of this nerve. It enters the orbit
above the muscles, through the highest and broadest part of the sphenoidal fissure,
and runs forwards along the middle line, between the Levator palpebral and the
periosteum. Midway between the apex and base of this cavity, it divides into
two branches, supra-trochlear and supra-orbital.
The supra-trochlear branch, the smaller of the two, passes inwards, above the
pulley of the Superior oblique muscle, and gives off a descending filament, which
joins with the infra-trochlear branch of the nasal nerve. It then escapes from
the orbit between the pulley of the Superior oblique and the supra-orbital foramen,
curves up on to the forehead close to the bone, and ascends behind the Corru gator
supercilii and Occipito-frontalis muscles, to both of which it is distributed
finally, it is lost in the integument of the forehead.
SUPERIOR MAXILLARY NERVE. 547
The supra-orbital branch passes forwards through the supra-orbital foramen,
and gives oftj in this situation, palpebral filaments to the upper eyelid. It then
ascends upon the forehead, and terminates in muscular, cutaneous, and pericranial
branches. The muscular branches supply the Corrugator supercilii, Occipito-
frontalis, and Orbicularis palpebrarum, joining in the substance of the latter
muscle with the facial nerve. The cutaneous branches, two in number, an inner
and an outer, supply the integument of the cranium as far back as the occiput.
They are at first situated beneath the Occipito-frontalis, the inner branch per-
forating the frontal portion of the muscle, the outer branch its tendinous aponeu-
rosis. The pericranial branches are distributed to the pericranium over the
frontal and parietal bones. They are derived from the cutaneous branches whilst
beneath the muscle.
The Nasal nerve is intermediate in size between the frontal and lachrymal,
and more deeply placed than the other branches of the ophthalmic. It enters the
orbit between the two heads of the External rectus, passes obliquely inwards
across the optic nerve beneath the Levator palpebras and Superior rectus muscles,
to the inner wall of this cavity, where it enters the anterior ethmoidal foramen,
immediately below the Superior oblique. It then enters the cavity of the cranium,
traverses 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, where it divides into two branches, an internal and an external. The
internal branch supplies the mucous membrane near the fore part of the septum
of the nose. The external branch descends in a groove on the inner surface of
the nasal bone, and supplies a few filaments to the mucous membrane covering the
fore part of the outer wall of the nares as far as the inferior spongy bone ; it
then leaves the cavity of the nose, between the lower border of the nasal bone and
the upper lateral cartilage of the nose, and, passing down beneath the Com-
pressor naris, supplies the integument of the ala and tip of the nose, joining with
the facial nerve.
The branches of the nasal nerve are the ganglionic, ciliary, and infra-
trochlear.
The ganglionic is a long, slender branch, about half an inch in length, which
usually arises from the nasal, between the two heads of the External rectus. It
passes forwards on the outer side of the optic nerve, and enters the superior and
posterior angle of the ciliary ganglion, forming its superior or 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, two or three in number, are given off from the nasal
as it crosses the optic nerve. They join the short ciliary nerves from the ciliary
ganglion, pierce the posterior part of the sclerotic, and, running forwards between
it and the choroid, are distributed to the Ciliary muscle and iris.
The infra- trochlear branch is given off just as the nasal nerve passes through
the anterior ethmoidal foramen. It runs forwards along the upper border of the
Internal rectus, and is joined, beneath the pulley of the Superior oblique, by a
filament from the supra-trochlear nerve. It then passes to the inner angle of the
eye, and supplies the Orbicularis palpebrarum, the integument of the eyelids and
side of the nose, the conjunctiva, lachrymal sac, and caruncula lacrymalis.
(2.) Superior Maxillary Nerve (fig. 280).
The Superior Maxillary, the second division of the fifth, is a sensory nerve.
It is intermediate, both in position and size, between the ophthalmic and inferior
maxillary. It commences at the middle of the Casserian ganglion as a flattened
plexiform band, and passes forwards through the foramen rotundum, where it be-
comes more cylindrical in form, and firmer in texture. It then crosses the spheno-
maxillary fossa, traverses the infra-orbital canal in the floor of the orbit, and ap-
pears upon the face at the infra-orbital foramen. At its termination, the nerve
548
CRANIAL NERVES.
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.
The branches of this nerve may be divided into three groups : 1. Those given
off in the spheno-maxillary fossa. 2. Those in the infra-orbital canal. 3. Those
on the face.
I Orbital.
Spheno-maxillary fossa •< Spheno-palatine.
( Posterior dental.
Infra-orbital canal
On the face . .
Anterior dental.
{Palpebral.
Nasal.
, Labial.
The Orbital 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.
Fig. 280. — Distribution of the Second and Third Divisions of the Fifth Nerve
and Submaxillary Ganglion.
The temporal branch runs in a groove along the outer wall of the orbit (in the
malar bone), receives a branch of communication from the lachrymal, and, passing
through a foramen in the malar bone, enters the temporal fossa. It ascends
between the bone and 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 auriculotemporal branch of the inferior maxillary nerve.
The malar branch passes along the external inferior angle of the orbit, emerges
INFERIOR MAXILLARY NERVE. 549
upon the face through a foramen in the malar bone, and, perforating the Orbi-
cularis palpebrarum muscle on the prominence of the cheek, joins with the
facial.
The Spheno-palatine branches, two in number, descend to the spheno-palatine
ganglion.
The Posterior dental branches arise from the trunk of the nerve just as it is
about to enter the infra-orbital canal; they are two in number, posterior and
anterior.
The posterior branch passes from behind forwards in the substance of the supe-
rior maxillary bone, and joins opposite the canine fossa with the anterior dental.
Numerous filaments are given off from the lower border of this nerve, which form
a minute plexus in the outer wall of the superior maxillary bone, immediately
above the alveolus. From this plexus, filaments are distributed to the pulps of
the molar and bicuspid teeth, the lining membrane of the antrum, and correspond-
ing portion of the gums.
The anterior branch is distributed to the gums and Buccinator muscle.
The Anterior dental, of large size, is given off from the superior maxillary nerve
just before its exit from the infra-orbital foramen ; it enters a special canal in the
anterior wall of the antrum, and anastomoses with the posterior dental. From
this nerve some filaments are distributed to the incisor, canine, and first bicuspid
teeth ; others are lost upon the lining membrane covering the fore part of the
inferior meatus.
The Palpebral branches pass upwards beneath the Orbicularis palpebrarum.
They supply this muscle, the integument, and conjunctiva of the lower eyelid,
joining at the outer angle of the orbit with the facial nerve and malar branch of
the orbital.
The Nasal branches pass inwards ; they supply the muscles and integument of
the side of the nose, and join with the nasal branch of the ophthalmic.
The Labial branches, the largest and most numerous, descend beneath the Leva-
tor labii superioris, and are distributed to the integument and muscles of the upper
lip, the mucous membrane of the mouth, and labial glands.
All these branches are joined, immediately beneath the orbit, by filaments from
the facial nerve, forming an intricate plexus, the infra-orbital.
(3.) Inferior Maxillary Nerve.
The Inferior Maxillary Nerve distributes 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 one of its special nerves of the sense of taste. It is the largest of
the three divisions of the fifth, and consists of two portions, the larger or sensory
root, proceeding from the inferior angle of the Casserian ganglion; and the smaller
or motor root, which passes beneath the ganglion, and unites with the inferior
maxillary nerve, just after its exit through the foramen ovale. Immediately
beneath the base of the skull, this nerve divides into two trunks, anterior and
posterior.
The Anterior and smaller division, which receives nearly the whole of the motor
root, divides into five branches, which supply the muscles of mastication. They
are the masseteric, deep temporal, buccal, and pterygoid.
The masseteric branch passes outwards, above the External pterygoid muscle, in
front of the temporo-maxillary articulation, and crosses the sigmoid notch, with
the masseteric artery, to 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, two in number, anterior and posterior, supply the
deep surface of the temporal muscle. The posterior branch, of small size, is
"aced at the back of the temporal fossa. It is sometimes joined with the
550 CRANIAL NERVES.
masseteric branch. The anterior branch is reflected upwards, at the pterygoid
ridge of the sphenoid, to the front of the temporal fossa. It is occasionally joined
with the buccal nerve.
The buccal branch pierces the External pterygoid, and passes downwards
beneath the inner surface of the coronoid process of the lower jaw or through the
fibres of the Temporal muscle, to reach the surface of the Buccinator, upon which
it divides into a superior and an inferior branch. It gives a branch to the External
pterygoid during its passage through this 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 upper branch supplies the integument and upper
part of the Buccinator muscle, joining with the facial nerve round the facial vein.
The lower branch passes forwards to the angle of the mouth ; supplies the integu-
ment and Buccinator muscle, as well as the mucous membrane lining its inner
surface, joining with the facial nerve.
The pterygoid branches are two in number, one for each Pterygoid muscle.
The branch to the Internal pterygoid is long and slender, and passes inwards to
enter the deep surface of the muscle. This nerve is intimately connected at its
origin with the otic ganglion. The branch to the External pterygoid is most
frequently derived from the buccal, but it may be given off separately from the
anterior trunk of the nerve.
The Posterior and larger division of the inferior maxillary nerve also receives
a few filaments from the motor root. It divides into three branches, auriculo-
temporal, gustatory, and inferior dental.
The Auriculo-tempoeal Nerve generally arises by two roots, between which
passes the middle meningeal artery. It passes backwards beneath the External
pterygoid muscle to the inner side of the articulation of the lower jaw. It then
turns upwards with the temporal artery, between the external ear and condyle of
the jaw, under cover of the parotid gland, and, escaping from beneath this struc-
ture, divides into two temporal branches. The posterior temporal, the smaller
of the two, supplies the Attrahens aurem muscle, and is distributed to the upper
part of the pinna and the neighboring integument. The anterior temporal
accompanies the temporal artery to the vertex of the skull, and supplies the
integument of the temporal region, communicating with the facial nerve.
The auriculo-temporal nerve has branches of communication with the facial
and otic ganglion. Those joining the facial nerve, usually two in number, pass
forwards behind the neck of the condyle of the jaw, and 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 fifth nerve. The filaments of com-
munication with the otic ganglion are derived from the commencement of the
auriculo-temporal nerve.
The auricular branches are two in number, inferior and superior. The inferior
auricular arises behind the articulation of the jaw, and is distributed to the ear
below the external meatus ; other filaments twine round the internal maxillary
artery, and communicate with the sympathetic. The superior auricular arises
in front of the internal ear, and supplies the integument covering the tragus and
pinna.
Branches to the meatus auditorius, two in number, arise from the point of com-
munication between the temporo-auricular and facial nerves, and are distributed
to the meatus.
The branch to the temporo-maxillary articulation is usually derived from the
auriculo-temporal nerve.
The parotid branches supply the parotid gland.
The Gustatory or Lingual Nerve (fig. 280), one of the special nerves of the
sense of taste, supplies the papillas and mucous membrane 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 the latter nerve, and is occasionally joined to it by a branch
GAXGLIA OF THE FIFTH NERVE. 551
which crosses the internal maxillary artery. The chorda tympani 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 muscle of the pharynx, and
between the Stylo-glossus muscle and deep part of the submaxillary gland ; the
nerve lastly runs across Wharton's duct, and along the side of the tongue to its
apex, being covered by the mucous membrane of the mouth.
Its branches of communication are with the submaxillary ganglion and hypo-
glossal nerve. 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.
Its branches of distribution are few in number. They supply the mucous mem-
brane of the mouth, the gums, the sublingual gland, the conical and fungiform
papillae and mucous membrane of the tongue, the terminal filaments anastomosing
at the tip of this organ with the hypoglossal nerve.
The Inferior Dental is the largest of the three branches of the inferior
maxillary nerve. It passes downwards 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 forwards
in the dental canal in 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 incisor branch is continued onwards within the bone to the middle
line, and supplies the canine and incisor teeth. The mental branch emerges from
the bone at the mental foramen, and divides beneath the Depressor anguli oris
into an external branch, which supplies this muscle, the Orbicularis oris, and the
integument, communicating with the facial nerve ; and an inner branch, which
ascends to the lower lip beneath the Quadratus menti and supplies this muscle and
the mucous membrane and integument of the lip, communicating with the facial
nerve. '
The branches of the inferior dental are the mylo-hyoid and dental.
The Mylo-hyoid is divided 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 membrane. It
supplies the cutaneous surface of the Mylo-hyoid muscle, and the anterior belly
of the Digastric, occasionally sending one or two filaments to the submaxillary
gland.
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.
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, the
gustatory.
Ganglia connected with the Fifth Nerve.
Connected with the three divisions of the fifth nerve are four small ganglia,
which form the whole of the cephalic portion of the sympathetic. With the first
division is connected the ophthalmic ganglion ; with the second division, the spheno-
palatine or Meckel's ganglion ; and with the third, the otic and submaxillary
ganglia. These ganglia receive sensitive filaments from the fifth, and motor and
sympathetic filaments from various sources ; these filaments are called the roots of
the ganglia. The ganglia are also connected with each other, and with the
cervical portion of the sympathetic.
(1.) Ophthalmic or Ciliary Ganglion.
The Ophthalmic, Lenticular or Ciliary Ganglion (fig. 276) is a small,
quadrangular, flattened ganglion, of a reddish-gray color, and about the size of a
552 CRANIAL NERVES.
pin's head, situated at the back part of the orbit between the optic nerve and the
External rectus muscle, generally lying on the outer side of the ophthalmic artery.
It is inclosed in a quantity of loose fat, which makes its dissection somewhat
difficult.
Its branches of communication, or its roots, are three, all of which enter its
posterior border. One, the long root, is derived from the nasal branch of the
ophthalmic, and joins its superior angle. Another branch, the short root, is a short
thick nerve, occasionally divided into two parts ; it is derived from that branch
of the third nerve which supplies the Inferior oblique muscle, and is connected
with the inferior angle of the ganglion. A third branch, the sympathetic root, is a
slender filament from the cavernous plexus of the sympathetic. This is occasion-
ally blended with the long root, and sometimes passes to the ganglion separately.
According to Tiedemann, this ganglion receives a filament of communication from
the spheno-palatine ganglion.
Its branches of distribution are the short ciliary nerves. These consist of from
ten to twelve delicate filaments, which arise from the fore part of the ganglion in
two bundles, connected with its superior and inferior angles ; the upper bundle
consisting of four filaments, and the lower of six or seven. They run forwards
with the ciliary arteries in a wavy course, one set above and the other below the
optic nerve, pierce the sclerotic at the back part of the globe, pass forwards in
delicate grooves on its inner surface, and are distributed to the Ciliary muscle and
iris. A small filament is described by Tiedemann, penetrating the optic nerve
with the arteria centralis retinas.
(2.) Spheno-palatine Ganglion.
The Spheno-palatine Ganglion or Meckel's Ganglion (fig. 281), 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 in form, of a reddish-
gray color, and placed mainly behind the palatine branches of the superior maxil-
lary nerve, at the point where the sympathetic root joins the ganglion^ It conse-
quently does not involve those nerves which pass to the palate and nose. Like
other ganglia, it possesses a motor, a sensory, and a sympathetic root. Its motor
root is derived from the facial, through the Vidian ; its sensory root from the fifth ;
and its sympathetic root from the carotid plexus, through the Vidian. Its branches
are divisible into four groups ; ascending, which pass to the orbit ; descending, to
the palate ; internal, to the nose ; and posterior branches to the pharynx.
The Ascending branches are two or three delicate filaments, which enter the orbit
by the spheno-maxillary fissure, and supply the periosteum. Arnold describes and
delineates these branches as descending to the optic nerve ; one, to the sixth nerve
(Bock) ; and one, to the ophthalmic ganglion (Tiedemann).
The Descending or Palatine branches 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 descends through the posterior palatine
canal, emerges upon the hard palate, at the posterior palatine foramen, and passes
forwards through a groove in the hard palate, nearly as far as the incisor teeth.
It supplies the gums, the mucoUs membrane and glands of the hard palate, and com-
municates in front with the termination of the naso-palatine nerve. While in the
posterior palatine canal, it gives off inferior nasal branches, which enter the nose
through openings in the palate-bone,, and ramify over the middle meatus, and the
middle and inferior spongy bones; 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, descends in the same canal as the pre-
ceding, to the posterior palatine foramen, distributing branches to the uvula,
tonsil, and soft palate. It is occasionally wanting.
SPHENO-PALATINE GANGLION.
553
The posterior or small palatine nerve descends with a small 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, the soft palate, tonsil, and uvula.
The Internal branches are distributed to the septum, and outer wall of the nasal
fossae. They are the superior nasal (anterior), and the naso-palatine.
The superior nasal branches (anterior), four or five 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 (Cotunnius) enters the nasal fossa with the other
nasal nerves, and passes inwards across the roof of the nose, below the orifice
of the sphenoidal sinus, to reach the septum ; it then runs obliquely downwards
and forwards 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 by a distinct canal, which opens below in the anterior palatine fossa ;
the right nerve, also in a separate canal, being posterior to the left one. In the
mouth, they become united, and supply the mucous membrane behind the incisor
teeth, joining with the anterior palatine nerve. It occasionally furnishes a few
small filaments to the mucous membrane of the septum.
281. — The Spheno-palatine Ganglion and its Branches.
Term* <f
The Posterior branches are the Vidian and pharyngeal or pterygopalatine.
The Vidian arises from the back part of the spheno-palatine ganglion, passes
through the Vidian canal, enters the cartilage filling in the foramen lacerum basis
cranii, and divides into two branches, the large petrosal and the carotid. In its
course along the Vidian canal, it distributes a few filaments to the lining membrane
at the back part of the roof of the nose and septum, and that covering the end
of the Eustachian tube. These are upper posterior nasal branches.
The large petrosal branch (nervus petrosus superficialis major) enters the cranium
through the foramen lacerum basis cranii, having pierced the cartilaginous sub-
stance filling in this aperture. It runs beneath the Casserian ganglion and dura
554
CRANIAL NERVES.
mater, contained in a groove in the anterior surface of the petrous portion of the
temporal bone, enters the hiatus Fallopii, and, being continued through it, into
the aquseductus Fallopii, joins the gangliform enlargement on the facial nerve.
Properly speaking, this nerve passes from the facial to the spheno-palatine
ganglion, forming its motor root.
The carotid branch is shorter but larger than the petrosal, of a reddish-gray
color, and soft in texture. It crosses the foramen lacerum, surrounded by .the
cartilaginous substance which fills in that aperture, and enters the carotid canal,
on the outer side of the carotid artery, to join the carotid plexus.
The Pharyngeal nerve (ptery go-palatine) is a small branch arising from the back
part of the ganglion, occasionally springing from the Vidian nerve. It passes
through the pterygopalatine canal with the pterygo-palatine artery, and is dis-
tributed to the lining membrane of the pharynx, behind the Eustachian tube.
(3.) Otic or Arnold's Ganglion.
The Otic Ganglion (Arnold's) is a small, oval-shaped, flattened ganglion of a
reddish-gray color, situated immediately below the foramen ovale, on the inner
surface of the inferior maxillary nerve, and round the origin of the internal
pterygoid nerve (fig. 282). It is in relation, externally, with the trunk of the infe-
rior maxillary nerve, at the point where the motor root joins the sensory portion ;
internally, with the cartilaginous part of the Eustachian tube, and the origin of
the Tensor palati muscle ; behind it, is the middle meningeal artery.
Fig. 2S2. — The Otic Ganglion and its Branches.
Branches of communication. This ganglion is connected with the inferior
maxillary nerve, and its internal pterygoid branch, by two or three short, delicate
filaments, and also with the auriculo-temporal nerve ; from the former, it obtains
its motor, from the latter, its sensory root; its communication with the sympathetic
being effected by a filament from the plexus surrounding the middle meningeal
artery. This ganglion also communicates with the glossopharyngeal and facial
nerves, through the small petrosal nerve continued from the tympanic plexus.
Its branches of distribution are a filament to the Tensor tympani, and one to the
Tensor palati. The former passes backwards, on the outer side of the Eustachian
tube ; the latter arises from the ganglion, near the origin of the internal pterygoid
nerve, and passes forwards.
EIGHTH PAIR. 555
(4.) Submaxillary Ganglion.
The Submaxillary Ganglion (fig. 280) is of small size, circular in form, and
situated above tie 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 gustatory nerve.
Branches of communication. This ganglion is connected with the gustatory
nerve by a few filaments 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 nervi
molles, surrounding 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. According to Meckel,
a branch from this ganglion occasionally descends in front of the Hyo-glossus
muscle, and, after joining with one from the hypoglossal, passes to the Gemo-
hyo-glossus muscle.
Eighth Pair.
The eighth pair consists of three nerves, the glossopharyngeal, pneumogastric,
and spinal accessory.
(1.) Glosso-pharyngeal Nerve.
The Glosso-pharyngeal Nerve is distributed, as its name implies, to the
tongue and pharynx, being the nerve of .
° . , Ki J t_ e *t Fi<r. 283.— Origin of the Eighth Pair, their
sensation to the mucous membrane ol the ° Gauglia aud communications.
pharynx, fauces, and tonsil ; of motion, to ^yrf-trt»jt
the Pharyngeal muscles, and a special *^^ [ ■**—■ a«»s*-
nerve of taste, in all the parts of the
tongue to which it is distributed. It is
the smallest of the three divisions of the
eighth pair, and arises by three or four
filaments, closely connected together, from
the upper part of the medulla oblongata,
immediately behind the olivary body.
Its deep origin may be traced through p««J^!ki></
the fasciculi of the lateral tract, to a
nucleus of gray matter at the lower part of the floor of the fourth ventricle,
external to the fasciculi teretes. From its superficial origin, it passes outwards
across the flocculus, and leaves the skull at the central part of the jugular foramen,
in a separate sheath of the dura mater and arachnoid, in front of the pneumogastric
and spinal accessory nerves. In its passage through the jugular foramen, it grooves
the lower border of the petrous portion of the temporal bone ; and, at its exit from
the skull, passes forwards between the jugular vein and internal carotid artery,
and descends in front of the latter vessel, and beneath the styloid process and the
muscles connected with it, to the lower border of the Stylo-pharyngeus. The nerve
now curves inwards, forming an arch on the side of the neck, lying upon the
Stylo-pharyngeus and the Middle constrictor of the pharynx, above the superior
laryngeal nerve. It*then passes beneath the Hyo-glossus, and is finally distributed
to the mucous membrane of the fauces, and base of the tongue, the mucous glands
of the mouth and tonsil.
In passing through the jugular foramen, the nerve presents, in succession, two
gangliform enlargements. The superior one, the smaller, is called the jugular
ganglion ; the inferior and larger one, the petrous ganglion or the ganglion of
Andersch.
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
556
CRANIAL NERVES,
is of very small size, and involves only the outer side of the trunk of the nerve,
a small fasciculus passing
Fig. 284.— Course and Distribution of the Eighth Pair of beyond it which is not
connected directly with it.
The inferior or petrous
ganglion is situated in a
depression in the lower
border of the petrous por-
tion of the temporal bone;
it is larger than the for-
mer, and involves the whole
of the fibres of the nerve.
From this ganglion arise
those filaments which con-
nect the glossopharyngeal
with other nerves at the
base of the skull.
Its branches of communi-
cation are with the pneu-
mogastric, sympathetic,
and facial, and the tympanic
branch.
The branches to the
pneumogastric are two fila-
ments, one to its auricular
branch, and one to the up-
per ganglion of the pneu-
mogastric.
The branch to the sym-
pathetic is connected with
the superior cervical gan-
glion.
The branch of commu-
nication with the facial
perforates the posterior
belly of the Digastric. It
arises from the trunk of
the nerve below the petrous
ganglion, and joins the fa-
cial just after its exit from
the stylo-mastoid foramen.
The tympanic branch
(Jacobson's nerve) arises
from the petrous ganglion,
and enters a small bony
canal on the base of the
petrous portion of the tem-
poral bone. (This opening
is placed on the bony ridge
which separates the ca-
rotid canal from the jugular
fossa.) It ascends to the
tympanum, enters this cavity by an aperture in its floor close to the inner wall,
and divides into three branches, which are contained in grooves upon the surface
of the promontory.
Its branches of distribution are, one to the fenestra rotunda, one to the fenestra
ovalis, and one to the lining membrane of the Eustachian tube and tympanum.
EIGHTH PAIR. 55T
Its branches of communication are three, and occupy separate grooves on the
surface of the promontory. One of these arches forwards and downwards to the
carotid canal to join the carotid plexus. A second runs vertically upwards to
join the greater superficial petrosal nerve, as it lies in the hiatus Fallopii. The
third branch runs forwards and upwards towards the anterior surface of the petrous
bone, and passes through a small aperture in the sphenoid and temporal bones, to
the exterior of the skull, where it joins the otic ganglion. This nerve, in its course
through the temporal bone, passes by the ganglionic enlargement of the facial, and
has a connecting filament with it.
The branches of the glosso-pharyngeal nerve are the carotid, pharyngeal, mus-
cular, tonsillitic, and lingual.
The carotid branches descend along the trunk of the internal carotid artery as
far as its point of bifurcation, communicating with the pharyngeal branch of the
pneumogastric, and with branches of the sympathetic.
The pharyngeal branches are three or four filaments which unite opposite the
Middle constrictor of the pharynx with the pharyngeal branches of the pneumo-
gastric, superior laryngeal, and sympathetic nerves, to form the pharyngeal plexus,
branches from which perforate the muscular coat of the pharynx to supply the
mucous membrane.
The muscular branches are distributed to the Stylo-pharyngeus.
The tonsillitic 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 anastomose with the palatine nerves.
The lingual branches are two in number; one supplies the mucous membrane
covering the surface of the base of the tongue, the other perforates its substance,
and supplies the mucous membrane and papillae of the side of the organ.
(2.) Pneumogastric or Par Yagum Nerve.
The Pneumogastric Nerve (nervus vagus or par vagum), one of the three
divisions of the eighth pair, has a more extensive distribution than any of the
other cranial nerves, passing through the neck and cavity of the chest to the upper
part of the abdomen. It is composed of both motor and sensitive filaments. It
supplies the organs of voice and respiration with motor and sensitive fibres, and
the pharynx, oesophagus, stomach, and heart with motor influence. Its superficial
origin is by eight or ten filaments from the lateral tract immediately behind the
olivary body, and below the glosso-pharyngeal ; its fibres may, however, be traced
deeply through the fasciculi of the medulla, to terminate in a gray nucleus near
the lower part of the floor of the fourth ventricle. The filaments become united,
and form a flat cord, which passes outwards across the flocculus to the jugular
foramen, through which it emerges from the cranium. In passing through this
opening, the pneumogastric accompanies the spinal accessory, being contained in
the same sheath of dura mater with it, a membranous septum separating it from
the glosso-pharyngeal, which lies in front. The nerve in this situation presents a
well-marked ganglionic enlargement, which is called ganglion jugulare or the
ganglion of the root of the pneumogastric ; to it the accessory part of the spinal
accessory nerve is connected. After the exit of the nerve from the jugular
foramen, a second gangliform swelling is formed upon it, called the ganglion infe-
rius or the ganglion of the trunk of the nerve; below which it is again joined by
filaments from the sjxinal accessory nerve. The nerve descends the neck in a straight
direction within the sheath of the carotid vessels, lying between the internal caro-
tid artery and internal jugular vein as far as the thyroid cartilage, and then be-
tween the same vein and the common carotid to the root of the neck. Here the
course of the nerve becomes different on the two sides of the body.
On the right side, the nerve passes across the subclavian artery between it and
the subclavian 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 (posterior pulmonary),
558 CRANIAL NERVES.
from the lower part of which two cords descend upon the oesophagus, on which
they divide, forming, with branches from the opposite nerve, the oesophageal
plexus ; 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
posterior surface of the stomach, joining the left side of the coeliac plexus, and the
splenic plexus.
On the left side, the pneumogastric 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, and along the
anterior surface of the oesophagus to the stomach, distributing branches over its
anterior surface, some extending over the great cul-de-sac, and others along the
lesser curvature. Filaments from these latter branches enter the gastro-hepatic
omentum, and join the left hepatic plexus.
The ganglion of the root is of a grayish color, circular in form, about two lines
in diameter, and resembles the ganglion on the large root of the fiftb nerve.
Connecting branches. To this ganglion the accessory portion of the spinal
accessory nerve is connected by several delicate filaments; it also has an anasto-
motic twig with the petrous ganglion of the glossopharyngeal, with the facial
nerve by means of the auricular branch, and with the sympathetic by means of an
ascending filament from the superior cervical ganglion.
The ganglion of the trunk (inferior) is a plexiform cord, cylindrical in form, of
a reddish color, and about an inch in length ; it involves the whole of the fibres
of the nerve, except the portion of the accessory nerve derived from the spinal
accessory, which blends with the nerve beyond the ganglion.
Connecting branches. This ganglion is connected with the hypoglossal, the supe-
rior cervical ganglion of the sympathetic, and with the loop between the first and
second cervical nerves.
The branches of the pneumogastric are —
In the jugular fossa . . Auricular.
[" Pharyngeal.
In the neck. . . J Superior laryngeal.
] Eecurrent laryngeal.
[ Cervical cardiac,
f Thoracic cardiac.
In the thorax. . . J Anterior pulmonary.
.Posterior pulmonary.
[ (Esophageal.
In the abdomen . . . Gastric.
The Auricular branch arises from the ganglion of the root, and is joined soon
after its origin by a filament from the glosso-pharyngeal ; it crosses the jugular
fossa to an opening near the root of the styloid process. Traversing the substance
of the temporal bone, it crosses the aquaaductus Fallopii about two lines above its
termination at the stylo-mastoid foramen ; it here gives off an ascending branch,
which joins the facial, and a descending branch, which anastomoses with the pos-
terior auricular branch of the same nerve ; the continuation of the nerve reaches
the surface between the mastoid process and the external auditory meatus, and
supplies the integument at the back part of the pinna.
The Pharyngeal branch, the principal motor nerve of the pharynx and soft
palate, arises from the upper part of the inferior ganglion of the pneumogastric,
receiving a filament from the accessory portion of the spinal accessory ; it passes
across the internal carotid artery (in front or behind), to the upper border of the
Middle constrictor, where it divides into numerous filaments, which anastomose
with those from the glosso-pharyngeal, superior laryngeal, and sympathetic, to
form the pharyngeal plexus, from which branches are distributed to the muscles
and mucous membrane of the pharynx. As this nerve crosses the internal carotid,
some filaments are distributed, together with those from the glosso-pharyngeal,
upon the wall of this vessel.
EIGHTH PAIR. 559
The Sujierior laryngeal is the nerve of sensation to the larynx. It is larger
than the preceding, and arises from the middle of the inferior ganglion of the
pneumogastric. It descends, by the side of the pharynx, behind the internal
carotid, where it divides into two branches, the external and internal laryngeal.
The external laryngeal branch, the smaller, descends by the side of the
larynx, beneath the Sterno-thyroid, to supply the Crico-thyroid muscle and the
thyroid gland. 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 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, and the Arytenoid muscle,
anastomosing with the recurrent laryngeal.
The branches to the mucous membrane are distributed, some in front, to the
epiglottis, the base of the tongue, and epiglottidean gland ; and others pass back-
wards, in the aryteno-epiglottidean fold, to supply the mucous membrane sur-
rounding the superior orifice of the larynx, as well as the membrane which lines
the cavity of the larynx as low down as the vocal chord.
The filament to the Arytenoid muscle is distributed partly to it, and partly to
the mucous lining of the larynx.
The filament which joins with the recurrent laryngeal descends beneath the
mucous membrane on the posterior surface of the larynx, behind the lateral part
of the thyroid cartilage, where the two nerves become united.
The Inferior or recurrent laryngeal, 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 backwards round this vessel, and ascends obliquely to
the side of the trachea, behind the common carotid and inferior thyroid arteries.
On the left side, it arises in front of the arch of the aorta, and winds from before
backwards round the vessel at the point where the obliterated remains of the
ductus arteriosus are connected with it, and then ascends to the side of the trachea.
The nerves on both sides ascend in the groove between the trachea and oesophagus,
and, piercing the lower fibres of the Inferior constrictor muscle, enter 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, excepting the Crico-
thyroid, and joining with the superior laryngeal.
The recurrent laryngeal, as it winds round the subclavian artery and aorta,
gives off several cardiac filaments, which unite with cardiac branches from the
pneumogastric and sympathetic. As it ascends 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.
The Cervical cardiac branches, two or three in number, arise from the pneumo-
gastric, at the upper and lower part of the neck.
The superior branches are small, and communicate with the cardiac branches
of the sympathetic, and with the great cardiac plexus.
The inferior cardiac 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 in front of
the arteria innominata, and anastomoses with the superior cardiac nerve. On the
left side, it passes in front of the arch of the aorta, and anastomoses either with
the superior cardiac nerve or with the cardiac plexus.
The Thoracic cardiac branches, on the right side, arise from the trunk of the
pneumogastric, as it lies by the side of the trachea: passing inwards, they terminate
in the deep cardiac plexus. On the left side, they arise from the left recurrent
laryngeal nerve.
The Anterior pulmonary branches, two or three in number, and of small size,
are distributed on the anterior aspect of the root of the lungs. They join with
filaments from the sympathetic, and form the anterior pulmonary plexus.
560 CRANIAL NERVES.
The Posterior pulmonary tranches, more numerous and larger than the anterior,
are distributed on the posterior aspect of the root of the lung ; they are joined by
filaments from the third and fourth thoracic ganglia of the sympathetic, and form
the posterior pulmonary plexus. Branches from both plexuses accompany the
ramifications of the air-tubes through the substance of the lungs.
The (Esophageal branches are given off from the pneumogastric both above
and below the pulmonary branches. The latter are the more numerous and
largest. They form, together with branches from the opposite nerve, the oeso-
phageal plexus.
The Gastric branches are the terminal filaments of the pneumogastric nerve.
The nerve on the right side is distributed to the posterior surface of the stomach,
and joins the left side of the cceliac plexus, and the splenic plexus. The nerve
on the left side is distributed over the anterior surface of the stomach, some
filaments passing across the great cul-de-sac, and others along the lesser curvature.
They unite with branches of the right nerve and sympathetic, some filaments
passing through the lesser omentum to the left hepatic plexus.
(3.) Spinal Accessoey Nerve.
The Spinal Accessory Nerve consists of two parts ; one, the accessory part
to the vagus, and the other the spinal portion.
The accessory part, the smaller of the two, arises by four or five delicate
filaments from the lateral tract of the cord below the roots of the vagus ; these
filaments may be traced to a nucleus of gray matter at the back of the medulla,
below the origin of the vagus. It joins, in the jugular foramen, with the upper
ganglion of the vagus by one or two filaments, and is continued into the vagus
below the second ganglion. It gives branches to the pharyngeal and superior
laryngeal branches of the vagus.
The spinal portion, firm in texture, arises by several filaments from the lateral
tract of the cord, as low down as the sixth cervical nerve ; the fibres pierce the
tract, and are connected with the anterior horn of the gray crescent of the cord.
This portion of the nerve ascends between the ligamentum denticulaturn and the
posterior roots of the spinal nerves, enters the skull through the foramen magnum,
and is then directed outwards to the jugular foramen, through which it passes,
lying in the same sheath as the pneumogastric, separated from it by a fold of the
arachnoid, and is here connected with the accessory portion. At its exit from the
jugular foramen, it passes backwards behind the internal jugular vein, and descends
obliquely behind the Digastric and Stylo-hyoid muscles to the upper part of the
Sterno-mastoid. It pierces this muscle, and passes obliquely across the sub-
occipital triangle, to terminate in the deep surface of the Trapezius. This nerve
gives several branches to the Sterno-mastoid during its passage through it, and
joins in its substance with branches from the third cervical. In the sub-occipital
triangle it joins with the second and third cervical nerves, assists in the formation
of the cervical plexus, and occasionally of the great auricular nerve. On the
front of the Trapezius, it is reinforced by branches from the third, fourth, and
fifth cervical nerves, joins with the posterior branches of the spinal nerves, and is
distributed to the Trapezius, some filaments ascending and others descending in
its substance as far as its inferior angle.
4. Mixed Nerves.
The Pneumogastric and Spinal Accessory Nerves, which constitute this sub-
division, have already been described in connection with the Eighth Pair, of which
they form part.
For fuller details concerning the Cranial Nerves, the student may refer to F. Arnold's "Icones
Nervorum Capitis."
The Spinal Nerves.
The Spinal Nerves are so called, from taking their origin from the spinal cord,
and from being 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.
Dorsal . . .12 "
Lumbar . . . 5 "
Sacral . . . 5 ■
Coccygeal ... 1 pair.
It will be observed, that each group of nerves corresponds in number with the
vertebrae in each region, excepting in the cervical and coccygeal.
Each spinal nerve arises by two roots, an anterior or motor root, and a
posterior or sensitive root.
EOOTS OF THE SPINAL NERVES.
The anterior roots arise somewhat irregularly from a linear series of foramina,
on the antero-lateral column of the spinal cord, gradually approaching towards
the anterior median fissure as they descend.
The fibres of the anterior roots are, according to the researches of Mr. Lockhart
Clarke, attached to the anterior part of the antero-lateral column; and, after
penetrating horizontally through the longitudinal fibres of this tract, enter the
gray substance, where their fibrils cross each other and diverge in all directions,
like the expanded hairs of a brush, some of them running more or less longi-
tudinally upwards and downwards, and others decussating with those of the
opposite side through the anterior commissure in front of the central canal
(figs. 258 and 259). Kolliker states that many fibres of the anterior root enter the
lateral column of the same side, where, turning upwards, they pursue their course
as longitudinal fibres. In other respects, the description of the origin of the
anterior roots by these observers is very similar.
The posterior roots are all attached immediately to the posterior white columns
only ; but some of them pass through the gray substance into both the lateral and
anterior white columns. Within the gray substance, they run, longitudinally,
upwards and downwards; transversely,* through the posterior commissure to the
opposite side and into the anterior column of their own side (figs. 258 and 259).
The posterior roots of the nerves are larger, but the individual filaments are
finer and more delicate than those of the anterior. As their component fibrils
pass outwards, towards the aperture in the dura mater, they coalesce into two
bundles, receive a tubular sheath from this membrane, and enter the ganglion
which is developed upon each root.
The posterior root of the first cervical nerve forms an exception to these
characters. It is smaller than the anterior, has frequently no ganglion developed
upon it, and, when the ganglion exists, it is often situated within the dura mater.
The anterior roots are the smaller of the two devoid of any ganglionic
enlargement, and their component fibrils are collected into two bundles, near the
intervertebral foramina.
36 561
5G2 SPINAL NERVES.
Ganglia of the Spinal Nerves.
A ganglion is developed upon each posterior root of the spinal nerves.
These ganglia are of an oval form, of a reddish color, bear a proportion in size
to the nerves upon which they are formed, and are placed in the intervertebral
foramina, external to the point wh^re the nerves perforate the dura mater. Each
ganglion is bifid internally, where it is joined by the two bundles of the posterior
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 vertebras over which they pass. The ganglia,
also, of the sacral nerves are placed within the spinal canal ; and that on the
coccygeal nerve, also in the canal about the middle of its posterior root. Imme-
diately beyond the ganglion, the two roots coalesce, their fibres intermingle, and
the trunk thus formed passes out of the intervertebral foramen, and divides into an
anterior branch for the supply of the anterior part of the body, and a posterior
branch for the posterior part, each branch containing fibres from both roots.
Anterior Branches of the Spinal Nerves.
The anterior branches of the spinal nerves supply the parts of the body in front
of the spine, including the limbs. They are for the most part larger than the
posterior branches ; this increase of size being proportioned to the larger extent
of structures they are required to supply. Each branch is connected by slender
filaments with the sympathetic. In the dorsal region, the anterior branches of
the spinal nerves are completely separate from each other, and are uniform in
their distribution ; but in the cervical, lumbar, and sacral regions, they form in-
tricate plexuses previous to their distribution.
Posterior Branches of the Spinal Nerves.
The posterior brandies of the spinal nerves are generally smaller than the anterior,
they arise from the trunk resulting from the union of the nerves in the interverte.
bral foramina, and, passing backwards, divide into external and internal branches,
which are distributed to the muscles and integument behind the spine. The first
cervical and lower sacral nerves are exceptions to these characters.
Cervical Nerves.
The roots of the cervical nerves increase in size from the first to the fifth, and
then maintain the same size to the eighth. The posterior roots bear a proportion
to the anterior as 3' to 1, which is much greater than in any other region ; the
individual filaments being also much larger than those of the anterior roots. In
direction, they are less oblique than those of the other spinal nerves. The first
is directed a little upwards and outwards ; the second is horizontal ; the others
are directed obliquely downwards and outwards, 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 spinal canal never exceeding the depth of one
vertebra.
The trunk of the first cervical nerve {suboccipital), leaves the spinal canal, between
the occipital bone and the posterior arch of the atlas; the second between the
posterior arch of the atlas and the lamina of the axis ; and the eighth (the last),
between the last cervical and first dorsal vertebras.
Each nerve, at its exit from the intervertebral foramen, divides into an anterior
and a posterior branch. The anterior branches of the four upper cervical nerves
form the cervical plexus. The anterior branches of the four lower cervical nerves,
together with the first dorsal, form the brachial plexus.
CERVICAL PLEXUS.
563
Anterior Branches of the Cervical Nerves.
The anterior branch of the first or suboccipital nerve is of small size. It escapes
from the spinal canal, through a groove upon the posterior arch of the atlas. In
this groove it lies beneath the vertebral artery, to the inner side of the Rectus
lateralis. As it crosses the foramen in the transverse process of the atlas, it
receives a filament from the sympathetic. It then descends, in front of this process,
to communicate with an ascending branch from the second cervical nerve.
Communicating filaments from this nerve join the pneumogastric, the hypo-
glossal and sympathetic, and some branches are distributed to the Rectus lateralis
and the two Anterior recti. According to Valentin, it also distributes filaments
to the occipito-atloid articulation, and mastoid process of the temporal bone.
The anterior branch of the second cervical nerve escapes from the spinal canal,
between the posterior arch of the atlas and the lamina of the axis, and, passing
forwards on the outer side of the vertebral artery, divides in front of the Inter-
transverse muscle, into an ascending branch, which joins the first cervical, and
two descending branches Avhich join the third.
The anterior branch of the third cervical nerve is double the size of the preceding.
At its exit from the intervertebral foramen, it passes downwards and outwards
beneath the Sterno-mastoid, and divides into two branches. The ascending branch
joins the anterior division of the second cervical, communicates with the sympa-
thetic and spinal accessory nerves, and subdivides into the superficial cervical,
and great auricular nerves. The descending branch passes down in front of the
Scalenus anticus, anastomoses with the fourth cervical nerve, and becomes con-
tinuous with the clavicular nerves.
The anterior branch of the fourth cervical 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 downwards and outwards, divides into numerous filaments,
which cross the posterior triangle of the neck, towards the clavicle and acromion.
It usually gives a branch to the phrenic nerve whilst it is contained in the inter-
transverse space.
The anterior branches of the fifth, sixth, seventh, and eighth cervical nerves are
remarkable for their large size. They are much larger than the preceding nerves,
and are all of equal size. They assist in the formation of the brachial plexus.
Cervical Plexus.
The cervical plexus (fig. 279) is formed by the anterior branches of the four
upper cervical nerves. It is situated in front of the four upper vertebras, 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 : —
Ascending
Superficial
SSuperficialis colli.
Auricularis magnus.
Occipitalis minor.
(
Descending -\ Supra-clavicular
\
Sternal.
Clavicular.
Acromial.
Deep
Internal
External
f Communicating.
J Muscular.
j Communicans noni.
[ Phrenic.
( Communicating.
I Muscular.
564
SPINAL NERVES. *V ' -v^/^^^^^
Superficial Branches of the Cervical Plexus.
The Superficialis Colli arises from the second and third cervical nerves, turns
round the posterior border of the Sterno-mastoid about its middle, and, passing
obliquely forwards behind the external jugular vein to the anterior border of that
muscle, perforates the deep cervical fascia, and divides beneath the Platysma into
two branches, which are distributed to the anterior and lateral parts of the neck.
The ascending branch gives a filament, which accompanies the external jugular
vein; it then passes upwards 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 this muscle, supply i*» an(i are distri-
buted to the integument of the upper half of the neck, at its fore part, as high
as the chin.
The descending branch pierces the Platysma, and is distributed to the integument
of the side and front of the neck, as low as the sternum.
This nerve is occasionally represented by two or more filaments.
The Auricularis Magnus is the largest of the ascending branches. It arises
from the second and third cervical nerves, winds Tound the posterior 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 numerous
branches.
The facial branches pass across the carotid, and are distributed to the integu-
ment of the face ; others penetrate the substance of the gland, and communicate
with the facial nerve.
The posterior or auricular branches ascend vertically to supply the integument
of the back part of the pinna, communicating with the auricular branches of the
facial and pneumogastric nerves.
The mastoid branch joins the posterior auricular branch of the facial, and, crossing
the mastoid process, is distributed to the integument behind the ear.
The Occipitalis Minor arises from the second cervical nerve ; it curves round
the posterior border of the Sterno-mastoid above the preceding, aud ascends
vertically along the posterior border of this muscle to the back part of the side
of the head. Near the cranium it perforates the deep fascia, and is continued
upwards along the side of the head behind the ear, supplying the integument and
Occipito-frontalis muscle, and communicating with the occipitalis major, auricu-
laris magnus, and posterior auricular branch of the facial.
This nerve gives off an auricular branch, which supplies the Attollens aurem
and the integument of the upper and back part of the auricle. This branch is
occasionally derived from the great occipital nerve. The occipitalis minor varies
in size ; it is occasionally double.
The Descending or Supra-clavicular branches arise from the third and fourth
cervical nerves; emerging beneath the posterior border of the Sterno-mastoid, they
descend in the interval between this muscle and the Trapezius, and divide into
branches, which are arranged, according to their position, into three groups.
The inner or sternal branch crosses obliquely over the clavicular and sternal
attachments of the Sterno-mastoid, and supplies the integument as far as the
median line.
The middle or clavicular branch crosses the clavicle, and supplies the integu-
ment over the Pectoral and Deltoid muscles, communicating with the cutaneous
branches of the upper intercostal nerves. Not unfrequently, the clavicular
branch passes through a foramen in the clavicle, at the junction of the outer with
the inner two-thirds of the bone.
The external or acromial branch passes obliquely across the outer surface of the
Trapezius and the acromion, and supplies the integument of the upper and back
part of the shoulder.
COMMUNICANS NONI — PHRENIC. 565
Deep Branches of the Cervical Plexus. Internal Series.
The communicating branches consist of several filaments, which pass from the
loop between the first and second cervical nerves in front of the atlas to the
pneumogastric, hypoglossal, and sympathetic.
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 Communicans Noni (fig. 279) consists usually of two filaments, one being
derived from the second, and the other from the third cervical. These filaments
pass vertically downwards on the outer side of the internal jugular vein, cross in
front of the vein a little beiow the middle of the neck, and form a loop with the
descendens noni in front of the sheath of the carotid vessels. Occasionally, the
junction of these nerves takes place within the sheath.
The Phrenic Nerve {internal respiratory of Bell) arises from the third and
fourth cervical nerves, and receives a communicating branch from the fifth. It
descends to the root of the neck, lying obliquely across the front of the Scalenus
anticus, 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 root. Within the chest, it descends nearly vertically in front 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, which
separately pierce that muscle, and are distributed to its under surface.
The two phrenic nerves differ in their length, and also in their relations at the
upper part of the thorax.
The right nerve 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
superior vena cava.
The left nerve is rather longer than the right, from the inclination of the heart
to the left side, and from the Diaphragm being lower in this than on the opposite
side. At the upper part of the thorax, it crosses in front of the arch of the aorta
to the root of the lung.
Each nerve supplies filaments to the pericardium and pleura, and near the chest
is joined by a filament from the sympathetic, by another derived from the fifth
and sixth cervical nerves, and, occasionally, by one from the union of the
descendens noni with the spinal nerves, which, Swan states, occurs only on the
left side.
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
distributed to the hepatic plexus, the supra-renal capsule, and inferior vena cava.
From the left nerve, filaments pass to join the phrenic plexus, but without any
ganglionic enlargement.
Deep Branches of the Cervical Plexus. External Series.
Communicating branches. The cervical plexus communicates with the spinal
accessory nerve, in the substance of the Sterno-mastoid muscle, in the subocci-
pital triangle, and beneath the Trapezius.
Muscular brandies are distributed to the Sterno-mastoid, Levator anguli
scapulas, Scalenus medius and Trapezius.
The branch for the Sterno-mastoid is derived from the second cervical ; the
Levator anguli scapulas receiving branches from the third ; and the Trapezius
branches from the third and fourth.
Posterior Branches of the Cervical Nerves.
The posterior branches of the cervical nerves, with the exception of the first
two, pass backwards, and divide, behind the posterior Inter-transverse muscles, into
external and internal branches.
5G6 SPINAL NERVES.
The external branches supply the muscles at the side of the neck, viz., the
Cervicalis ascendens, Transversalis colli, and Trachelo-mastoid.
The external branch of the second cervical nerve is the largest; it is often
joined with the third, and supplies the Complexus, Splenius, and Trachelo-
mastoid muscles.
The internal branches, the larger, are distributed differently in the upper and
lower part of the neck. Those derived from the third, fourth, and fifth serves
pass between the Semi-spinalis and Complexus muscles, and, having reached the
spinous processes, perforate the aponeurosis of the Splenius and Trapezius, and
are continued outwards 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, which they supply, and do not furnish any cutaneous filaments.
These internal branches supply the Complexus, Semi-spinalis colli, Inter-spinales,
and Multifidus spinse.
The posterior branches of the three first cervical nerves require a separate
description.
The 'posterior branches of the first cervical nerve {suboccipital) is larger than the
anterior, and escapes from the spinal canal between the occipital bone and the
posterior arch of the atlas, lying behind the vertebral artery, and enters the tri-
angular space formed by the Kectus posticus major, the Obliquus superior, and
Obliquus inferior. It supplies the Kecti and Obliqui muscles, and the Com-
plexus. From the branch which supplies the Inferior oblique a filament is given
off, which joins the second cervical nerve. It also occasionally gives off a cuta-
neous filament, which accompanies the occipital artery, and communicates with the
occipitalis major and minor nerves.
The posterior division of the first cervical has no branch analogous to the
external branch of the other cervical nerves.
The posterior branch of the second cervical nerve is three or four times greater
than the anterior branch, and the largest of all the other posterior cervical nerves.
It emerges from the spinal canal between the posterior arch of the atlas and
lamina of the axis, below the Inferior oblique. It supplies this muscle, and
receives a communicating filament from the first cervical. It then divides into
an external and an internal branch.
The internal branch, called, from its size and distribution, the occipitalis major,
ascends obliquely inwards between the Obliquus 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 third cervical nerve, 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 forwards 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 posterior branch of the third cervical is smaller than the preceding, but
larger than the fourth ; it differs from the posterior branches of the other cervical
nerves in its supplying an additional filament to the integument of the occiput.
This occipital branch arises from the internal or cutaneous branch beneath the
Trapezius ; it 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 internal branches of the posterior divisions of the first three cervical
nerves are occasionally joined beneath the Complexus by communicating branches.
This communication has been described by Cruveilhier as the posterior cervical
plexus.
The Beachial Plexus (fig. 285).
The brachial plexus is formed by the union of the anterior branches of the four
lower cervical and first dorsal nerves. It extends from the lower part of the side
of the neck to tne axilla, being very broad, and presenting but little of a plexi-
BRACHIAL PLEXUS.
5G7
^Fasciculus f rem
if'.1! Cerv.tf.
Comnrnnicati-ny vriOi Phrenic
Sup ra -Scapular
" °f Clavicle
form arrangement at its commencement, narrow opposite the clavicle, broad and
presenting a more dense interlacement in the axilla, and dividing opposite the
coracoid process into numerous branches for the supply of the upper limb. These
nerves are all similar in size, and their mode of union in the formation of the
plexus is the following. The fifth and sixth nerves unite near their exit from
the spine into a common trunk ; the seventh nerve joins this trunk near the outer
border of the Middle scalenus ; and the three nerves thus form one large single
cord. The eighth cervical and first dorsal nerves unite beneath the Anterior
scalenus into a common trunk. Thus two large trunks are formed, the upper one
by the union of the fifth, sixth, and seventh cervical ; and the lower one by the
eighth cervical and first dorsal. These two trunks accompany the subclavian
artery to the axilla, lying upon its outer side, the trunk formed by the union of the
last cervical and first dorsal
being; nearest to the vessel. FiS- 285.— Plan of the Brachial Plexus.
Opposite the clavicle, and
sometimes in the axilla,
each of these cords gives
off a fasciculus, which
uniting, a third trunk is
formed, so that in the
centre of the axilla three
cords are found, one lying
on the outer side of the
axillary artery, one on its
inner side, and one behind.
The brachial plexus com-
municates with the cer-
vical plexus by a branch
from the fourth to the
fifth nerve, and with the
phrenic by a branch from
the fifth cervical, which
joins that nerve on the
Anterior scalenus muscle :
the cervical and first dor-
sal nerves are also joined
by filaments from the mid-
dle and inferior cervical
ganglia of the sympathetic,
close to their exit from the
intervertebral foramina.
Relations. In the neck, the brachial plexus lies at first between the Anterior
and Middle scaleni muscles, and then above and to the outer side of the subclavian
artery ; it then passes beneath the clavicle and Subclavius muscle, lying upon the
first serration of the Serratus magnus and Subscapularis muscles. 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.
The Branches of the Brachial Plexus may be arranged into two groups, viz.,
those given off above the clavicle, and those below that bone.
(1.) Branches above the Clavicle.
Communicating.
Muscular.
Posterior thoracic.
Suprascapular.
5G8 SPINAL NERVES.
The Communicating branch with, the phrenic is derived from the fifth cervical
nerve ; it joins the phrenic on the Anterior scalenus muscle.
The Muscular branches supply the Longus colli, Scaleni, Rhomboidei, and
Subclavius muscles. Those for the Scaleni and Longus colli arise from the lower
cervical nerves at their exit from the intervertebral foramina. The rhomboid branch
arises from the fifth cervical, pierces the Scalenus medius, and passes beneath the
Levator anguli scapulas, which it occasionally supplies, to the Rhomboid muscles.
The subclavian branch is a small filament, which arises from the trunk formed by
the junction of the fifth and sixth cervical nerves; it descends in front of the
subclavian artery to the Subclavius muscle, and is usually connected by a filament
with the phrenic nerve.
The Posterior thoracic nerve (long thoracic, external respiratory of Bell)
supplies the Serratus magnus, and is remarkable for the length of its course. It
arises by two roots, from the fifth and sixth cervical nerves, immediately 'after
their exit from the intervertebral foramina. These unite in the substance of the
Middle scalenus muscle, and, after emerging from it, the nerve passes down 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
this muscle, and supplies it with numerous filaments.
The Suprascapular nerve arises from the cord formed by the fifth, sixth, and
seventh cervical nerves ; passing obliquely outwards beneath the Trapezius, it enters
the supra-spinous fossa, through the notch in the upper border of the scapula ;
and, passing beneath the Supra-spinatus muscle, curves in front of the spine of the
scapula to the infra-spinous fossa. In the supra-spinous fossa, it gives off two
branches to the Supra-spinatus muscle, and an articular filament to the shoulder-
joint ; and in the infra-spinous fossa, it gives off two branches to the Infra- spinatus
muscle, besides some filaments to the shoulder-joint and scapula.
(2.) Branches below the Clavicle.
To the chest .... Anterior thoracic.
To the shoulder . . j Subscapular.
( Circumflex.
' Musculo-cutaneous.
Internal cutaneous.
Lesser internal cutaneous.
Median.
Ulnar.
Musculo-spiral.
The branches given off below the clavicle are derived from the three cords of
the brachial plexus, in the following manner: —
From the outer cord, arise the external of the two anterior thoracic nerves, the
musculo-cutaneous nerve, and the outer head of the median.
From the inner cord, arise the internal of the two anterior thoracic nerves, the
internal cutaneous, the lesser internal cutaneous (nerve of Wrisberg), the ulnar,
and inner head of the median.
From the posterior cord, arises the subscapular ; and it then subdivides into the
musculo-spiral and circumflex nerves.
The Anterior Thoracic Nerves, two in number, supply the Pectoral muscles.
The external or superficial branch, the larger of the two, arises from the outer
cord of the brachial plexus, passes inwards, across the axillary artery and vein.
and is distributed to the under surface of the Pectoralis major. It sends down a
communicating filament to join the internal branch.
The internal or deep branch arises from the inner cord, and passes upwards
between the axillary artery and vein (sometimes perforates the vein), and joins with
the filament from the superficial branch. From the loop thus formed, branches
are distributed to the under surface of the Pectoralis minor and Pectoralis major
muscles.
To the arm, forearm and hand 4
CUTANEOUS NERVES OF THE FOREARM.
569
The Subscapular Nerves, three in number, supply the Subscapular^ Teres
major, and Latissimus dorsi muscles.
The upper subscapular nerve, the smallest, enters the upper part of the Subsca-
pularis muscle.
The lower subscap>ular nerve enters
the axillary border of the Sub^laris, «* «*£££»« »SS& fif* UpP"
and terminates in the Teres major, lhe
latter muscle is sometimes supplied by a
separate branch.
The long subscapular, the largest of the
three, descends along the lower border of
the Subscapularis to the Latissimus dorsi,
through which it may be traced as far as
its lower border.
The Circumflex Nerve supplies some
of the muscles, and the integument of the
shoulder, and the shoulder -joint. It arises
from the posterior cord of the brachial
plexus, in common with the musculo-
spiral nerve. It passes down behind the
axillary artery, and in front of the Subsca-
pularis; and, at the lower border of this
muscle, passes backwards, and divides into
two branches.
The upper branch winds round the neck
of the humerus, beneath the Deltoid, with
the posterior circumflex vessels, as far as
the anterior border of the muscle, supply-
ing it, and giving off cutaneous branches,
which pierce it to ramify in the integument
covering its lower part.
The lower branch, at its origin, dis-
tributes filaments to the .Teres minor and
back part of the Deltoid muscles. Upon the
filament to the former muscle, a gangliform
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, as
well as that covering the long head of the
Triceps.
The circumflex nerve, before its divi-
sion, gives off an articular filament, which
enters the shoulder-joint below the Subsca-
pularis.
The Musculo-cutaneous Nerve {exter-
nal cutaneous, perforans Casserii) 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. It then perforates the Coraco-brachialis muscle, and passes
obliquely between the Biceps and Brachialis anticus, to the outer side of the arm,
a little above the elbow, where it perforates the deep fascia and becomes cutaneous.
This nerve, in its course through the arm, supplies the Coraco-brachialis, Biceps,
and Brachialis anticus muscles, besides some filaments to the elbow-joint and
humerus.
570
SPINAL NERVES.
Fit
287. — Cutaneous Nerves of Right Upper
Extremity. Posterior View.
_ The cutaneous portion of the nerve 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. It is here placed in front of the radial artery, and, piercing the deep
fascia, accompanies that vessel to the back of the wrist. It communicates with
a branch from the radial nerve, and dis-
tributes filaments to the integument of- the
ball of the thumb.
The posterior branch is given off about
the middle of the forearm, and passes
downwards, along the back part of its
radial side, 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 Internal Cutaneous Nerve is one
of the smallest branches of the brachial
plexus. It arises from the inner cord,
in common with the ulnar and internal
head of the median, and, at its commence-
ment, is placed on the inner side of the
brachial artery. 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, di-
vides into two branches.
This nerve gives off, near the axilla, a
cutaneous filament, which pierces the
fascia, and supplies the integument cover-
ing the Biceps muscle, nearly as far as
the elbow. This filament lies a little ex-
ternal to the common trunk from which
it arises.
The anterior branch, the larger of the
two, passes in front of, occasionally be-
hind, 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 cuta-
neous branch of the ulnar nerve.
The posterior branch passes obliquely
downwards on the inner side of the basilic
vein, winds over the internal condyle of
the humerus to the back of the forearm,
and descends, on the posterior surface of
its ulnar side, to a little below the middle,
distributing filaments to the integument.
It anastomoses above the elbow with
the lesser internal cutaneous, and above
the wrist with the dorsal branch of the
ulnar nerve (Swan).
The Lesser Internal Cutaneous Nerve
(nerve of Wrisberg) is distributed to the
integument on the inner side of the arm. It is the smallest of the branches of the
brachial plexus, and usually arises from the inner cord, with the internal cutaneous
MEDIAN. 5TI
and ulnar nerves. It passes through the axillary space, at first lying beneath, and
then on the inner side of, the axillary vein, and communicates with the intercosto-
humeral nerve. It then 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 part of the lower third of the arm, extending as far as the
elbow, where some filaments are lost in the integument in front of the inner con-
dyle, and others over the olecranon. It communicates with the inner branch of
the internal cutaneous nerve.
In some cases, the nerve of Wrisberg and intercosto-humeral are connected
by two or three filaments, which form a plexus at the back part of the axilla.
In other cases, the intercosto-humeral is of large size, and takes the place of the
nerve of Wrisberg, receiving merely a filament of communication from the
brachial plexus, which represents this nerve. In other cases, this filament is
wanting, the place of the nerve of Wrisberg being supplied entirely from the
intercosto-humeral.
The Mediax Nerve (fig. 288) has received its name from the course it takes
along the middle line of the arm and forearm to the hand, lying between the ulnar
and musculo-spiral and 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.
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 occa-
sionally 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. In the forearm, it passes between the two heads of the
Pronator radii teres, and descends beneath the Flexor sublimis, to within two
inches above the annular ligament, where it becomes more superficial, lying between
the Flexor sublimis and Flexor carpi radialis, covered by the integument and
fascia. It then passes beneath the annular ligament into the hand.
Branches. No branches are given off from the median nerve in the arm.
In the forearm, its branches are the muscular, anterior interosseous, and palmar
cutaneous.
The muscular branches 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 branch furnished to the Pronator radii teres often
arises above the joint.
The anterior interosseous supplies the deep muscles on the front of the fore-
arm. It accompanies the anterior interosseous artery along the interosseous
membrane, in the interval between the Flexor longus pollicis and Flexor pro-
fundus digitorum rnuscles, both of which it supplies, and terminates below in the
Pronator quadratus.
The palmar cutaneous branch arises from the median nerve at the lower part
of the forearm. It pierces the fascia above the annular ligament, and divides
into two branches; the outer one supplies the skin over the ball of the thumb, and
communicates with the external cutaneous nerve ; the inner one supplies the inte-
gument of the palm of the hand, anastomosing with the cutaneous branch of the
ulnar. Both nerves cross the annular ligament previous to their distribution.
In the palm of the hand, the median nerve is covered by the integument and
palmar fascia, and rests upon the 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 one supplies a muscular branch to some of the
muscles of the thumb, and digital branches to the thumb and index-finger; the
internal branch supplying digital branches to the middle finger and part of the
index and ring fingers.
The branch to the muscles of the thumb is a short nerve, which subdivides to
supply the Abductor, Opponens, and outer head of the Flexor brevis pollicis
muscles ; the remaining muscles of this group being supplied by the ulnar nerve.
572
SPINAL NERVES.
Pig. 288.— Nerves of the Left Upper Extremity. Front View.
External
'Anterior T7u>raete
Tntemat
ULNAR. 573
The digital branches are five in number. The first and second pass along the
borders of the thumb, the most external one communicating with branches of
the radial nerve. The third passes along the radial side of the index-finger, and
supplies the first Lumbrical muscle. The fourth subdivides to supply the adjacent
sides of the index and middle fingers, and sends a branch to the second Lumbrical
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, and runs along the side of the
dorsum of the finger, ending 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 supplies the extremity of the finger, and the latter ramifies round and
beneath the nail. The digital nerves, as they run along the fingers, are placed
superficial to the digital arteries.
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 nerves.
At its commencement, it lies at 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 olecranon, accompanied by the inferior 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. In the forearm, it descends in a
perfectly straight course along its ulnar side, lying upon the Flexor profundus
digitorum, its upper half being covered by the Flexor carpi ulnaris, its lower half
lying on the outer side of this muscle, covered by the integument and fascia. The
ulnar artery, in the upper part 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, a little behind the ulnar artery, and immediately beyond this
bone divides into two branches, superficial and deep palmar.
The branches of the ulnar nerve are : —
' Articular (elbow).
-Musculir
In the forearm A Cutaneous. In hand 1 Superficial palmar,
j Dorsal branch. 1 Deep palmar.
[ Articular (wrist).
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 and olecranon.
The muscular branches are two in number; one supplying the Flexor carpi
ulnaris ; the other, the inner half of the Flexor profundus digitorum. 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 a superficial and deep branch.
The superficial 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 deep branch lies on the ulnar artery, which it accompanies to the hand,
some filaments entwining round the vessel, which end in the integument of the
palm, communicating with branches of the median nerve.
The dorsal cutaneous branch arises about two inches above the wrist ; it passes
backwards beneath the Flexor carpi ulnaris, perforates the deep fascia, and, running
574
SPINAL NERYES.
Fig. 289. — The Suprascapular, Circumflex, and Musculo-spiral
Nerves.
Supra-Seetyuli
Circumflex
along the ulnar side of the wrist and hand, supplies the inner side of the little
finger, and the adjoining sides of the little and ring fingers ; it also sends a com-
municating filament to that branch of the radial nerve which supplies the adjoining
sides of the middle and ring fingers.
The articular filaments to the wrist are also supplied by the ulnar nerve.
The superficial palmar branch 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 com-
municating with a branch
from the median.
The deep palmar branch
passes between the Abduc-
tor and Flexor brevis
minimi digiti muscles, 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 interos-
seous space, one for the
Dorsal and one for the
Palmar interosseous mus-
cle, the branches to the
second and third Palmar
interossei supplying fila-
ments to the two inner
Lumbrical muscles. At its
termination between the
thumb and index-finger, it
supplies the Adductor pol-
licis and the inner head of
the Flexor brevis pollicis.
The Musculo-spikal
Nerve (fig. 289), the largest
branch of the brachial
plexus, supplies the mus-
cles of the back part of the
arm and forearm, and the
integument of the same
parts, as well as that of
the hand. It arises from
the posterior cord of the
brachial plexus by a com-
mon trunk with the cir-
cumflex nerve. At its
commencement, it is placed
behind the axillary and
upper part of the brachial
arteries, passing down in
front of the tendons of the
Latissimus dorsi and Teres
major. It winds round
MUSCULO-SPIRAL. 515
the "humerus in the spiral groove with the superior profunda artery and vein,
passing from the inner to the outer side of the bone, beneath the Triceps muscle.
At the outer side of the arm, it descends between the Brachialis anticus and
Supinator longus to the front of the external condyle, where it divides into the
radial and posterior interosseous nerves.
The branches of the musculo-spiral nerve are : —
Muscular. Radial.
Cutaneous. Posterior interosseous.
The muscular branches supply the Triceps, Anconeus, Supinator longus,
Extensor carpi radialis longior, and Brachialis anticus. These branches are
derived from the nerve, at the inner side, back part, and outer side of the
arm.
The internal muscular branches supply the inner and middle heads of the
Triceps 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.
The posterior muscular branch, of large size, arises from the nerve in the
groove between the Triceps and the humerus. It divides into branches which
supply the outer head of the Triceps and 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 Brachialis anticus.
The cutaneous branches are three in number, one internal and two external.
The internal cutaneous branch arises in the axillary space, with the inner
muscular branch. It is of small size, and passes across the axilla to the inner
side of the arm, supplying the integument on its posterior aspect nearly as far as
the olecranon.
The two external cutaneous branches perforate the outer head of the Triceps,
at its attachment to the humerus. The upper and smaller one follows the course
of the cephalic vein to the front of the elbow, supplying the integument of the
lower half of the upper arm on its anterior aspect. The lower branch pierces the
deep fascia below the insertion of the Deltoid, and passes down along the outer
side of the arm and elbow, and 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 a branch of the external cutaneous nerve.
The radial nerve 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. In the middle third of the
forearm, it lies beneath the same muscle, in close relation with the outer side of
the artery. It quits the artery about three inches above the wrist, passes beneath
the tendon of the Supinator longus, 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 posterior branch of the
external cutaneous nerve.
The internal branch communicates, above the wrist, with a branch from the
external cutaneous, and, on the back of the hand, forms an arch with the dorsal
branch of the ulnar nerve. It then divides into four digital nerves, 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. The latter nerve communicates with a filament from the dorsal branch
of the ulnar nerve.
The posterior interosseous nerve pierces the Supinator brevis, winds to the back
of the forearm, in the substance of this muscle, and, emerging from its lower border,
5?6 SPINAL NERVES.
passes down between the superficial and deep layer of muscles, to the middle of
the forearm. Considerably diminished in size, it descends on the interosseous
membrane, beneath the Extensor secundi internodii pollicis, to the back of the
carpus, where it presents a gangliform enlargement, from which filaments are
distributed 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.
Dorsal Nerves.
The Dorsal Nerves are twelve in number on each side. The first appears
between the first and second dorsal vertebrae, and the last between the last dorsal
and first lumbar.
The roots of origin of the dorsal nerves are few in number, of small size, and
vary but slightly from the second to the last. Both roots are very slender ; the
posterior ones exceeding in thickness those of the anterior only in a slight degree.
These roots gradually increase in length from above downwards, and remain in
contact with the spinal cord for a distance equal to the height of, at least, two
vertebrae, in the lower part of the dorsal region. They then join in the inter-
vertebral foramen, and, at their exit, divide into two branches, a posterior or
dorsal, and an anterior or intercostal branch.
The first and last dorsal nerves are exceptions to these characters.
The posterior branches of the dorsal nerves, which are smaller than the intercostal,
pass backwards between the transverse processes, and divide into external and
internal branches.
The external branches increase in size from above downwards. They pass
through the Longissimus dorsi, corresponding to the cellular interval between it
and the Sacro-lumbalis, supplying these muscles, as well as those by which they
are continued upwards to the head, and the Levatores costarum ; the five or six
lower ones giving off cutaneous filaments.
The internal branches of the six upper nerves pass inwards to the interval
between the Multifidus spinas and Semi-spinalis dorsi muscles, which they supply;
then, piercing the origin of the Khomboidei and Trapezius, become cutaneous
by the side of the spinous processes. The internal branches of the six lower
nerves are distributed to the Multifidus spinas, without giving off any cutaneous
filaments.
The cutaneous branches of the dorsal nerves are twelve in number, the six
upper being derived from the internal branches, and the six lower from the ex-
ternal branches. The former pierce the Rhomboid and Trapezius muscles, close
to the spinous processes, and ramify in the integument. They are frequently
'furnished with gangliform enlargements. The six lower cutaneous branches
pierce the Serratus posticus inferior, and Latissimus dorsi, in a line with the
angles of the ribs.
Intercostal Nerves.
The Intercostal Nerves (anterior branches of the dorsal nerves) are twelve in
number on each side. They are distributed to the parietes of the thorax and
abdomen, separately from c;ich other, without being joined in a plexus, in which
respect they differ from all the other spinal nerves. Each nerve is connected with
the adjoining ganglia of the sympathetic by one or two filaments. The intercostal
nerves may be divided into two sets, from the difference they present in their dis-
tribution. The six upper, with the exception of the first, are limited in their
distribution to the parietes of the chest. The six lower supply the parietes of
the chest and abdomen.
The Upper Intercostal Nerves pass forwards in the intercostal spaces with
the intercostal vessels, lying below the veins and artery. At the back of the chest,
INTERCOSTAL. 5T7
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 costal car-
tilages, where they lie between the pleura and the Internal intercostal muscles.
Near the sternum, they cross the internal mammary artery, and Triangularis
sterni, pierce the Internal intercostal and Pectoralis major muscles, and supply the
integument of the mamma and front of the chest, forming the anterior cutaneous
nerves of the thorax ; that from the second nerve becoming joined with the cla-
vicular nerve.
Branches, Numerous slender muscular filaments supply the Intercostal and
Triangularis sterni muscles. Some of these branches, at the front of the chest,
cross the costal cartilages from one to another intercostal space.
Lateral cutaneous nerves. These are derived from the intercostal nerves, midway
between the vertebrae and sternum, pierce the External intercostal and Serratus
magnus muscles, and divide into two branches, anterior and posterior.
The anterior branches are reflected forwards to the side and forepart of the
chest, supplying the integument of the chest and mamma, and the upper digitations
of the External oblique.
The posterior branches are reflected backwards, to supply the integument over
the scapula and Latissimus dorsi.
The first intercostal nerve has no lateral cutaneous branch. The lateral cutaneous
branch of the second intercostal nerve is of large size, and named, from its origin
and distribution, the intercosto- humeral nerve. It pierces the External intercostal
muscle, crosses the axilla to the inner side of the arm, and joins with a filament
from the 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, communicating with the
internal cutaneous branch 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 intercosto-humeral nerve is frequently given off
from the third intercostal. It supplies filaments to the arm-pit and inner side of
the arm.
The Lower Intercostal Nerves (excepting the last) have the same arrangement
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 Trans-
versalis 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 (anterior cutaneous nerves of the abdomen), supplying the integument
in front of the abdomen, being directed outwards to the lateral cutaneous nerves.
The lower intercostal nerves supply the Intercostal and abdominal muscles, and,
about the middle of their course, give off lateral cutaneous branches, which pierce
the External intercostal and External oblique muscles, and are distributed to the
integument of the abdomen, the anterior branches passing nearly as far forwards
as the margin of the Rectus ; the posterior branches passing to supply the skin
over the Latissimus dorsi, where they join the dorsal cutaneous nerves.
Peculiar Dorsal Nerves.
First dorsal nerve. Its roots of origin are similar to those of a cervical nerve.
Its posterior or dorsal branch resembles, in its mode of distribution, the dorsal
branches of the cervical nerves. Its anterior branch enters almost wholly into the
formation of the brachial plexus, giving off, before it leaves the thorax, a small
intercostal branch, which runs along the first intercostal space, and terminates on
the front of the chest, by forming the first anterior cutaneous nerve of the thorax.
The first intercostal nerve gives off no lateral cutaneous branch.
The last dorsal is larger than the other dorsal nerves. Its anterior branch
runs along the lower border of the last rib in front of the Quadratus lumborum,
perforates the aponeurosis of the Transversalis, and passes forwards between it
and the Internal oblique, to be distributed in the same manner as the preceding
37
578 SPINAL NERYES.
nerves. It communicates with the iliohypogastric branch of the lumbar plexus,
and is occasionally connected with the first lumbar nerve by a slender branch,
the dorsi-lumbar nerve, which descends in the substance of the Quadratus lum-
borum.
The lateral cutaneous branch of the last dorsal is remarkable for its large size ;
it perforates the Internal and External oblique muscles, passes downwards over
the crest of the ilium, and is distributed to the integument of the front of the hip,
some of its filaments extending as low down as the trochanter major.
Lumbar Nerves.
The Lumbar nerves are five in number on each side ; the first appears between
the first and second lumbar vertebras, and the last between the last lumbar and the
base of the sacrum.
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 anterior roots are smaller ; but there is not the
same disproportion between them and the posterior 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, as the spinal cord does not extend beyond the first
lumbar vertebra. The roots become joined in the intervertebral foramina, and, at
their exit, divide into two branches, anterior and posterior.
The posterior branches of the lumbar nerves diminish in size from above down-
wards ; they pass backwards between the transverse processes, and divide into
external and internal branches.
The external branches supply the Erector spinas and Inter-transverse muscles.
From the three upper branches cutaneous nerves are derived, which pierce the
Sacro-lumbalis and Latissimus dorsi muscles, and descend over the back part 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.
The internal branches, the smaller, pass inwards close to the articular processes
of the vertebrae, and supply the Multifidus spinas and Inter-spinales muscles.
The anterior branches of the lumbar nerves increase in size from above down-
wards. At their origin, they communicate with the lumbar ganglia of the sym-
pathetic by long slender filaments, which accompany the lumbar arteries round the
sides of the bodies of the vertebrae, beneath the Psoas muscle. The nerves pass
obliquely outwards behind the Psoas magnus, or between its fasciculi, distributing
filaments to it and the Quadratus lumborum. The anterior branches of the four
upper nerves are connected together in this situation by anastomotic loops, and
form the lumbar plexus. The anterior branch of the fifth lumbar, joined with a
branch from the fourth, descends across the base of the sacrum to join the anterior
branch of the first sacral nerve, and assist in the formation of the sacral plexus.
The cord resulting from the union of these two nerves is called the lumbosacral
nerve.
Lumbar Plexus.
The Lumbar plexus is formed by the loops of communication between the ante-
rior branches of the four upper lumbar nerves. The plexus is narrow above, and
occasionally connected with the last dorsal by a slender branch, the dorsi-lumbar
nerve ; it is broad below, where it is joined to the sacral plexus by the lumbo-sacral.
It is situated in the substance of the Psoas muscle, near its posterior part, in front
of the transverse processes of the lumbar vertebrae.
The mode in which the plexus is formed is the following : — The first lumbar
nerve gives off the ilio-hypogastric and ilio-inguinal nerves, and a communicating
branch to the second. The second gives off the external cutaneous and genito-
crural, and a communicating branch to the third nerve. The third nerve gives a
descending filament to the fourth, and divides into two branches, which assist in
LUMBAR PLEXUS.
579
forming the anterior crural and obturator nerves. The fourth nerve completes the
formation of the anterior crural, and the obturator, furnishes part of the accessory
obturator, and gives off a communicating branch to the fifth lumbar.
The branches of the lumbar plexus are the
Ilio-hypogastric.
Ilio-inguinal.
Genito-crural.
External cutaneous.
Obturator.
Accessory obturator.
Anterior crural.
These branches may be divided into two groups, according to their mode of
distribution. One group, including the ilio-hypogastric, ilio-inguinal, and part
of the genito-crural nerves, supplies the lower part of the parietes of the abdomen ;
the other group, which includes the remaining nerves, supplies the forepart of the
thigh and inner side of the leg.
Fig. 290. — The Lumbar Plexus and its Branches.
The Ilio-hypogastric nerve (superior muscuh-cutaneous) arises from the first
lumbar nerve. It pierces the outer border of the Psoas muscle at its upper part,
and crosses obliquely in front of the Quadratus lumborum to the crest of the
ilium. It then perforates the Transversalis muscle at its back part, and divides
between it and the Internal oblique into two branches, iliac and hypogastric.
580 SPINAL NERVES.
The iliac hranch pierces the Internal and External oblique muscles imme-
diately above the crest of the ilium, and is distributed to the integument of the
gluteal region, behind the lateral cutaneous branch of the last dorsal nerve (fig.
293). The size of this nerve bears an inverse proportion to that of the cutaneous
branch of the last dorsal nerve.
The hypogastric branch continues onwards between the Internal oblique and
Transversalis muscles. It first pierces the Internal oblique, and near the middle
line perforates the External oblique above the external abdominal ring, and is
distributed to the integument covering the hypogastric region.
The Ilioinguinal nerve (inferior musculo-cutaneous), smaller than the pre-
ceding, arises with it from the first lumbar nerve. It pierces the outer border of
the Psoas just below the ilio-hypogastric, and, passing obliquely across the Quad-
ratus lumborum and Iliacus muscles, perforates the Transversalis, near the fore-
part 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 filaments to it, and, accompanying the spermatic cord, escapes
at the external abdominal ring, and is distributed to the integument of the
scrotum and upper and inner part of the thigh in the male and to the labium in
the female. The size of this nerve is in inverse proportion to that of the ilio-
hypogastric. Occasionally it is very small, and ends by joining it ; in such cases,
a branch from the ilio-hypogastric takes the place of that nerve, or the nerve may
be altogether absent.
The Genito-crueal Nerve arises from the second lumbar, and by a few fibres
from the cord of communication between it and the first. It passes obliquely
through the substance of the Psoas, descends on its surface to near Poupart's
ligament, and divides into a genital and a crural branch.
The genital hranch descends on the .external iliac artery, sending a few fila-
ments round that vessel; it then pierces the fascia transversalis, and, passing
through the internal abdominal ring, descends along the back part of the sper-
matic cord to the scrotum, and supplies, in the male, the Cremaster muscle. In
the female, it accompanies the round ligament, and is lost upon it.
The crural hranch passes along the inner margin of the Psoas muscle, beneath
Poupart's ligament, into the thigh, where it pierces the fascia lata, and is distri-
buted to the integument of the upper and anterior aspect of the thigh, communi-
cating with the middle cutaneous 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 External Cutaneous Nerve arises from the second lumbar, or from the
loop between it and the third. It perforates the outer border of the Psoas muscle
about its middle, and crosses the Iliacus muscle obliquely, to the notch imme-
diately beneath the anterior superior spine of the ilium, where it passes beneath
Poupart's ligament into the thigh, and divides into two branches of nearly equal
size.
The anterior hranch 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 com-
municates with the long saphenous nerve.
The posterior hranch pierces the fascia lata, and subdivides into branches which
pass across the outer and posterior surface of the thigh, supplying the integument
in this region as far as the middle of the thigh.
The Obturator Nerve supplies the Obturator externus and Adductor muscles
of the thigh, the articulations of the hip and knee, and occasionally the integu-
ment of the thigh and leg. It arises by two branches ; one from the third, the
other from the fourth lumbar nerve. 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
CUTANEOUS NERYBS OF LOWER EXTREMITY. 581
Fig. 291. — Cutaneous Nerves of Lower
Extremity. Front View.
Fig. 292.— Nerves of the Lower Extremity.
Front View.
1 •*./?<rfiXtn»ar.
.Md. Tibial
Anterior
Crural
A.ntBrierHivision
of Obturator
582 SPINAL NERVES.
upper part of the obturator foramen, where it enters the thigh, and divides
into an anterior and a posterior branch, separated by the Adductor brevis
muscle.
The anterior branch 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 internal saphenous nerves,
forming a kind of plexus. It then descends upon the femoral artery, upon which
it is finally distributed.
This 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 occasionally to the Adductor brevis and Pectineus, and
receives a communicating branch from the accessory obturator nerve.
Occasionally this communicating branch is continued down, as a cutaneous
branch, to the thigh and leg ; emerging from the lower border of the Adductor
longus, it 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 branch is small, its place is supplied by the
internal cutaneous nerve.
The posterior branch of the obturator nerve pierces the Obturator externus,
and passes behind the Adductor brevis to the front of the Adductor magnus,
where it divides into numerous muscular branches, which supply the Obturator
externus, the Adductor magnus, and occasionally the Adductor brevis.
The articular branch for the knee-joint perforates the lower part of the
Adductor magnus, and enters the upper part of the popliteal space ; descending
upon the popliteal artery, as far as the back part of the knee-joint, it perforates
the posterior ligament, and is distributed to the synovial membrane. It gives
filaments to the artery in its course.
The Accessory Obturator Nerve is of small size, and arises either from the
obturator nerve near its origin, or by separate filaments from the third and fourth
lumbar nerves. It descends along the inner border of the Psoas muscle, crosses
the body of the pubes, and passes beneath the Pectineus muscle, where it divides
into numerous branches. One of these supplies the Pectineus, penetrating its
under surface; another is distributed to the hip-joint; while a third communicates
with the anterior branch of the obturator nerve. This branch, when of large
size, is prolonged (as already mentioned), as a cutaneous branch, to the leg. The
accessory obturator nerve is not constantly found; when absent, the hip-joint
receives branches from the obturator nerve. Occasionally it is very small, and
becomes lost in the capsule of the hip-joint.
The Anterior Crural 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 vaginas femoris ; cutaneous filaments to
the front and inner side of the thigh, and to the leg and foot ; and articular branches
to the knee. It arises from the third and fourth lumbar nerves, receiving also a
fasciculus from the second. It descends through the fibres of the Psoas muscle,
emerging from it at the lower part of its outer border ; and passes down between
it and the Iliacus, and beneath Poupart's ligament, into the thigh, where it
becomes somewhat flattened, and divides into an anterior or cutaneous, and a
posterior or muscular part. Beneath Poupart's ligament, it is separated from the
femoral artery by the Psoas muscle, and lies beneath the iliac fascia.
Within the pelvis, the anterior crural nerve gives off from its outer side some
small 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: —
ANTERIOR CRURAL. 583
From the Anterior Division. From the Posterior Division-.
Middle cutaneous. Muscular.
Internal cutaneous. Articular.
Long saphenous.
The middle cutaneous nerve pierces the fascia lata (occasionally the Sartorius
also), about three inches below Poupart's ligament, and divides into two branches,
which descend in immediate proximity along the fore part of the thigh, distributing
numerous branches to the integument as low as the front of the knee, where it
joins a branch of the internal saphenous nerve. Its outer branch communicates,
above, with the crural branch of the genito-crural nerve ; and the inner branch
with the internal cutaneous nerve below. The Sartorius muscle is supplied by
this or the following nerve.
The internal cutaneous nerve passes obliquely across the upper part of the sheath
of the femoral artery, and divides in front of, or at the inner side of, that vessel, into
two branches, anterior and internal.
The anterior branch perforates the fascia lata at the lower third of the thigh,
and divides into two branches, one of which supplies the integument as low down
as the inner side of the knee ; the other crosses the patella to the outer side of
the joint, communicating in its course with the long saphenous nerve. A cuta-
neous filament is occasionally given off from this nerve, which accompanies the
long saphenous vein ; and it sometimes communicates with the internal branch
of the nerve.
The inner branch descends along the posterior border of the Sartorius muscle
to the knee, where it pierces the fascia lata, communicates with the long saphe-
nous 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, joins in a plexiform network, by uniting with
branches of the long saphenous and obturator nerves. "When the communicating
branch from the latter 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.
This nerve, before subdividing, gives off a few filaments, which pierce the
fascia lata, to supply the integument of the inner side of the thigh, accompanying
the long saphenous vein. One of these filaments passes through the saphenous
opening; a second becomes subcutaneous about the middle of the thigh ; and a third
pierces the fascia at its lower third.
The long or internal saphenous nerve is the largest of the cutaneous branches
of the anterior crural nerve. It approaches the femoral artery where this vessel
passes beneath the Sartorius, and lies on its outer side, beneath the aponeurotic
covering, as far as the opening in the lower part of the Adductor magnus.
It then quits the artery, and descends vertically along the inner side of the knee,
beneath the Sartorius, pierces the deep fascia between the tendons of the Sartorius
and Gracilis, and becomes subcutaneous. The nerve then passes along the inner
side of the leg, 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.
Branches. The long 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 branch (n. cutaneus patellse),
which pierces the Sartorius and fascia lata, and is distributed to the integument
in front of the patella. This nerve communicates, above the Jcnee, with the anterior
branch of the internal cutaneous ; below the Jcnee, with other branches of the long
saphenous ; and, on the outer side of the joint, with branches of the middle ami
JB4 SPINAL NERYES.
external cutaneous nerves, forming a plexiform network, the plexus patellae.
This nerve 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 long saphenous nerve are distributed to
the integument of the front and inner side of the leg, communicating with the
cutaneous branches from the internal cutaneous, or obturator nerve.
The deep group of branches of the anterior crural nerve are muscular and
articular.
The muscular branches supply the Pectineus, and all the muscles on the front
of the thigh, except the Tensor vaginas femoris, which is supplied from the
gluteal nerve, and the Sartorius, which is supplied by filaments from the middle
or internal cutaneous nerves.
The branches to the Pectineus, usually two in number, pass inwards behind the
femoral vessels, and enter the muscle on its anterior surface.
The branch to the Rectus muscle enters its under surface high up.
The branch to the Vastus externus, 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.
The branches to the Vastus internus and Crureus enter the middle of those
muscles.
The articular branches, two in number, supply the knee-joint. One, a long,
slender filament, is derived from the nerve to the Vastus externus ; it penetrates
the capsular ligament of the joint on its anterior aspect. The other is derived
from the nerve to the Vastus internus; it descends along the internal inter-
muscular septum, accompanying the deep branch of the anastomotica magna,
pierces the capsular ligament of the joint on its inner side, and supplies the
synovial membrane.
The Saceal and Coccygeal Nerves.
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 escaping through the
foramen between the sacrum and coccyx.
The roots of origin of the upper sacral (and lumbar) nerves are the largest of all
the spinal nerves ; whilst those of the lowest sacral and coccygeal nerves are the
smallest.
The length of the roots of these nerves is very considerable, being 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 the spinal cord, the roots of origin of these nerves
are called collectively the cauda equina. Each sacral and coccygeal nerve divides
into two branches, anterior and posterior.
The posterior sacral nerves are small, diminish in size from above downwards,
and emerge, except the last, from the sacral canal by the posterior sacral foramina.
The three upper ones are covered, at their exit from the sacral canal, by the
Multifidus spinas, and divide into external and internal branches.
The internal branches are small, and supply the Multifidus spinas.
The external branches communicate with one another, and with the last lumbar
and fourth sacral nerves, by means of anastomosing loops. These branches pass
outwards, to the outer surface of the great sacro-sciatic ligament, where they
form a second series of loops beneath the Gluteus maximus. Cutaneous branches
from these second series of loops, usually three in number, pierce this muscle,
one near the posterior inferior spine of the ilium ; another opposite the end of the
sacrum ; and the third, midway between these two. They supply the integument
over the posterior part of the gluteal region.
The two lower posterior sacral nerves are situated below the Multifidus spinas.
They are of small size, and join with each other, and with the coccygeal nerve,
SACRAL PLEXUS. 585
so as to iorm loops on the back of the sacrum, filaments from which supply the
LTumeut over the coccyx.
The posterior branch of the coccygeal nerve is small. It separates from the
anterior in the sacral canal, and receives, as already mentioned, a communicating
branch from the last sacral. It is lost in the fibrous structure on the back of the
coccyx.
The anterior sacral nerves diminish in size from above downwards. The
four upper ones emerge from the anterior sacral foramina ; the anterior branch of
the fifth, together with the coccygeal nerve, between the sacrum and the coccyx.
All the anterior sacral nerves communicate with the sacral ganglia of the sympa-
thetic, at their exit from the sacral foramina. The first nerve, of large size, unites
with the lumbo-sacral nerve. The second equals in size the preceding, with which
it joins. The third, about one-fourth the size of the second, unites with the
preceding nerves, to form the sacral plexus.
The fourth anterior 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 ; in the
female, upon the vagina and bladder, communicating with branches of the sympa-
thetic to form the hypogastric plexus. The muscular branches are distributed to
the Levator ani, Coccygeus, and Sphincter ani. Cutaneous filaments arise from
the latter branch, which supply the integument between the anus and coccyx.
The fifth anterior sacral nerve, after passing from the lower end of the sacral
canal, pierces the Coccygeus muscle, and descends upon its anterior surface to the
tip of the coccyx, where it perforates that muscle, to be distributed to the integu-
ment over the back- part and side of the coccyx. This nerve communicates above
with the fourth, and below with the coccygeal nerve, and supplies the Coccygeus
muscle.
The anterior branch of the coccygeal nerve is a delicate filament which escapes
at the termination of the sacral canal. It pierces the sacro-sciatic ligament and
Coccygeus muscle, is joined by a branch from the fifth anterior sacral, and
becomes lost in the integument at the back part and side of the coccyx.
Sacral Plexus.
The sacral plexus is formed by the lumbo-sacral, the anterior branches of the
three upper, and part of the fourth sacral nerves. These nerves proceed in
different directions ; the upper ones obliquely outwards, the lower one nearly
horizontally, and they all unite into a single, broad, flat cord. The sacral 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-sciatie foramen. It rests
upon the anterior surface of the Pyriformis, and is covered in front 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 branches of the sacral plexus are : —
Muscular. Pudic.
Superior gluteal. Small sciatic.
Great sciatic.
The muscular branches supply the Pyriformis, Obturator internus, the two
Gemelli, and the Quadratus femoris. The branch to the Pyriformis arises either
from the plexus, or from the upper sacral nerves ; the branch to the Obturator in-
ternus arises at the junction of the lumbo-sacral and first sacral nerves ; it crosses
behind the spine of the ischium, and passes through the lesser sacro-sciatic foramen
to the inner surface of the Obturator internus ; the branch to the Gemellus superior
arises from the lower part of the plexus, near the pudic nerve ; the small branch
586 SPINAL NERVES.
to the Gemellus inferior and Quadratus femoris also arises from the lower part of
the plexus, passes beneath the Gemelli and tendon of the Obturator mternws,
and supplies an articular branch to the hip-joint. This branch is occasionally
derived from the upper part of the great sciatic nerve.
The Superior Gluteal Nerve arises from the back part of the lumbo-sacral ;
it passes from the pelvis through the great sacro-sciatic foramen above the Piri-
formis 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 it and the Gluteus medius.
The inferior branch crosses obliquely between the Gluteus minimus and Gluteus
medius, distributing filaments to both these muscles, and terminates in the Tensor
vaginso femoris, extending nearly to its lower end.
The Pudic Nerve arises from the lower part of the sacral plexus, and 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 upwards and forwards along the
outer wall of the ischio-rectal fossa, being covered by the obturator fascia, and
divides into two terminal branches, the perineal nerve and the dorsal nerve of the
penis. Near its origin, it gives off the inferior hemorrhoidal nerve.
The inferior hemorrhoidal nerve is occasionally derived from the sacral
plexus. It passes across the ischio-rectal fossa, with its accompanying vessels,
towards the lower end of the rectum, and is distributed to the External sphincter
and the integument round the anus. Branches of this nerve communicate with
the inferior pudendal and superficial perineal nerves on the inner margin of the
thigh.
The -perineal nerve, the most inferior and largest 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 branch passes to the back part of the ischio-rectal fossa,
distributing filaments to the Sphincter ani and integument in front of the anus,
which communicate with the inferior hemorrhoidal nerve; it then passes for-
wards, with the anterior branch, to the back of the scrotum, communicating with
this nerve and the inferior pudendal. The anterior branch passes to the fore
part of the ischio-rectal fossa, in front of the preceding, and accompanies it to the
scrotum and under part of the penis. This branch gives one or two filaments to
the Levator ani.
The muscular branches are distributed to the Transversus perinei, Accelerator
urinae, Erector penis, and Compressor urethrse. The nerve of the bulb supplies
the corpus spongiosum ; some of its filaments run for some distance on the surface,
before penetrating its interior.
The dorsal nerve of the penis is the superior division of the pudic nerve ; it
accompanies the pudic artery along the ramus of the ischium, and between the
two layers of the deep perineal fascia ; it then pierces the suspensory ligament of
the penis, and accompanies the arteria dorsalis penis to the glans, to which it js
distributed. On the penis, this nerve gives off a cutaneous branch, which runs
along the side of the organ ; it is joined with branches of the sympathetic, and
supplies the integument of the upper surface and sides of the penis and prepuce,
giving a large branch to the corpus cavernosum.
In the female, the pudic nerve is distributed to the parts analogous to those in
the male; its superior division terminating in the clitoris, the inferior in the
external labia and perineum.
The Small Sciatic Nerve supplies the integument of the perineum and back
part of the thigh and leg, and one muscle, the Gluteus maximus. It is usually
formed by the union of two branches, which arise from the lower part of the
sacral plexus. It issues from the pelvis below the Pyriformis muscle, descends
SCIATIC.
587
Fig. 293. — Cutaneous Nerves of Lower
Extremity. Posterior View.
Fig. 294. — Nerves of the Lower Extremity.
Posterior View.
&l
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PurHo
X.tt OBTURATOR |||T,
Small Sciatic
Cotnmimicttnt
I'opUtrC
External
Popliteal ,.r
I'ero jitti t
Com muni earn
I'ero net
Plantaf
C*tem**M*
538 SPINAL NERVES.
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, to the
lower part of the popliteal region, where it pierces the fascia and becomes
cutaneous. It then accompanies the external saphenous vein below the middle of
the leg, its terminal filaments communicating with the external saphenous nerve.
The branches of -the small sciatic nerve are muscular (inferior gluteal) and
cutaneous.
The inferior gluteal consist of several large branches given off to the under
surface of the Gluteus maximus, near it lower part.
The cutaneous branches consist of two groups, internal and ascending.
The internal cutaneous branches 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, curves forward below the tuber ischii, pierces the fascia lata on
the outer side of the ramus of that bone, and is distributed to the integument of
the scrotum, communicating with the superficial perineal nerve.
The ascending cutaneous branches consist of two or three filaments, which
turn upwards round the lower border of the Gluteus maximus, to supply the
integument covering its surface. One or two filaments occasionally descend
along the outer side of the thigh, supplying the integument as far as the middle
of this region.
Two or three branches are given off from the lesser sciatic nerve as it descends
beneath the fascia of the thigh ; they supply the integument of the back part of
the thigh, popliteal region, and upper part of the leg.
The Geeat Sciatic Nerve supplies nearly the whole of the integument of the
leg, the muscles of the back of the thigh, and of the leg and foot. It is the largest
nervous cord in the body, measuring three-quarters of an inch in breadth, and is
the continuation of the lower part 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 and external popliteal nerves.
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, 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 at first upon the external rotator
muscles, together with the small sciatic nerve and artery, being covered by the
Gluteus maximus ; lower down, it lies upon the Adductor magnus, being covered
by the long head of the Biceps.
The branches of the nerve, before its division, are articular and muscular.
The articular branches arise from the upper part of the nerve ; they supply the
hip-joint, perforating its fibrous capsule posteriorly. These branches are some-
times derived from the sacral plexus.
The muscular branches are distributed to the Flexors of the leg; viz., the
Biceps, Semi-tendinosus, and Semi-membranosus, and a branch to the Adductor
magnus. These branches are given off beneath the Biceps muscle.
The Internal Popliteal Nerve, the larger of the two terminal branches of
the great sciatic nerve, 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 artery beneath the arch of the Soleus, and becomes the posterior
tibial. It lies at first very superficial, and at the outer side of the popliteal vessels;
opposite the knee-joint, it is in close relation with these vessels, and crosses the
artery to its inner side.
The branches of this nerve are articular, muscular, and a cutaneous branch, the
external or short saphenous nerve.
The articular branches, usually three in number, supply the knee-joint ; two of
PLANTAR.
5S9
Fig. 295.— The Plantar Nerves.
these branches accompany the superior and inferior internal articular arteries, and
a third the azygos.
The muscular branches, four or five in number, arise from the nerve as it lies
between the two heads of the Gastrocnemius muscle ; they supply this muscle,
the Plantaris, Soleus, and Popliteus.
The external or short saphenous nerve descends between the two heads of the
Gastrocnemius muscle, and, about the middle of the back of the leg, pierces the
deep fascia, and receives a communicating branch (communicans peronei) from the
external popliteal nerve. The nerve then continues its course down the leg near
the outer margin of the tendo Achillis, in company with the external saphenous
vein, winds round 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.
The Posterior Tibial nerve 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 by the deep fascia, the superficial muscles, and integument. 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 posterior tibial
nerve are muscular and plantar cutaneous.
The muscular branches arise either
separately or by a common trunk from
the upper part of the nerve. They supply
the Tibialis posticus, Flexor longus digi-
torum, and Flexor longus pollicis muscles ;
the branch to the latter muscle accompanies
the peroneal artery.
The plantar cutaneous branch perforates
the internal annular ligament, and sup-
plies the integument of the heel and inner
side of the sole of the foot.
The internal plantar nerve (fig. 295),
the larger of the two terminal branches
of the posterior tibial, accompanies the
internal, plantar artery along the inner
side of the foot. From its origin at the
inner ankle it passes forwards between
the Abductor pollicis and Flexor brevis
digitorum, divides opposite the bases of
the metatarsal bones into four digital
branches, and communicates with the
external plantar nerve.
Branches. In its course, the internal
plantar nerve givb3 oft' cutaneous branches,
which pierce the plantar fascia, and supply
the integument of the sole of the foot;
muscular branches, which supply the
Abductor pollicis and Flexor brevis digi-
torum ; articular branches to the articulations of the tarsus and metatarsus ; and
four digital branches. These pierce the plantar fascia in the clefts between the
toes, and are distributed in the following manner : — The first supplies the inner
border of the great toe, and sends a filament to the Flexor brevis pollicis muscle;
the second bifurcates, to supply the adjacent sides of the great and second toes,
590 SPINAL NERVES.
sending a filament to the first Lumbrical muscle; the third digital branch supplies
the adjacent sides of the second and third toes, and the second Lumbrical muscle ;
the fourth supplies the corresponding sides of the third and fourth toes, and
receives a communicating branch from the external plantar nerve. It will be
observed, that the distribution of these branches is precisely similar to that of
the median. Each digital nerve gives off cutaneous and articular filaments;
and opposite the last phalanx sends a dorsal branch, which supplies the structures
round the nail, the continuation of the nerve being distributed to the ball of
the toe.
The external plantar nerve, the smaller of the two, completes the nervous supply
to the structures of the foot, being distributed to the little toe and one half of the
fourth, as well as to some of the deep muscles. It passes obliquely forwards
with the external 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 superficial and a deep
branch. Before its division, it supplies the Flexor accessorius and Abductor
minimi digiti.
The superficial branch separates into two digital nerves : one, 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 com-
municates with the internal plantar nerve.
The deep or muscular branch accompanies the external plantar artery into the
deep part of the sole of the foot, beneath the tendons of the Flexor muscles and
Adductor pollicis, and supplies all the Interossei (except those in the fourth
metatarsal space), the two outer Lumbricales, the Adductor pollicis, and the
Transversus pedis.
The External Popliteal or Peroneal Nerve, about one-half the size of
the internal popliteal, descends obliquely along the outer side of the popliteal
space, close to the margin of the Biceps muscle, to the fibula; and, about an inch
below the head of this bone, pierces the origin of the Peroneus longus, and
divides beneath this muscle into the anterior tibial and musculo-cutaneous nerves.
The branches of the peroneal nerve, previous to its division, are articular and
cutaneous.
The articular branches, two in number, accompany the superior and inferior
' external articular arteries to the outer side of the knee. The upper one occa-
sionally arises from the great sciatic nerve before its bifurcation. A third
(recurrent) articular nerve is given off at the point of division of the peroneal
nerve; it ascends with the tibial recurrent artery through the Tibialis antic us
muscle to the front of the knee, which it supplies.
The cutaneous branches, two or three in number, supply the integument along
the back part and outer side of the leg, as far as its middle or lower part ; one of
these, larger than the rest, the communicans peronei, arises near the head of the
fibula, crosses the external head of the Gastrocnemius to the middle of the leg,
where it joins with the external saphenous. This nerve occasionally exists as a
separate branch, which is continued down as far as the heel.
The Anterior Tibial Nerve commences at the bifurcation of the peroneal nerve,
between the fibula and upper part of the Peroneus longus, passes obliquely for-
wards beneath the Extensor longus digitorum to the fore part of the interosseous
membrane, and reaches the outer side of 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, then in front of it, and again at its outer
side at the ankle-joint.
The branches of the anterior tibial, in its course through the leg, are muscular :
these supply the Tibialis anticus, the Extensor longus digitorum, and Extensor
proprius pollicis muscles.
CUTANEOUS NERVES OP FOOT. 591
The external or tarsal branch of the anterior tibial passes outwards across the
tarsus, beneath the Extensor brevis digitorum, and, having become ganglionic,
like the posterior interosseous nerve at the wrist, supplies the Extensor brevis
digitorum and the articulations of the tarsus and metatarsus.
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 branches, which supply the adjacent sides of the
great and second toes, communicating with the internal division of the musculo-
cutaneous nerve.
The Musculo-cutaneous branch supplies the muscles on the fibular side of the
leg, and the integument of the dorsum of the foot. It passes forwards 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 to the Peroneus longus and Peroneus brevis, and cutaneous filaments to
the integument of the lower part of the leg.
The internal branch of the musculo-cutaneous nerve passes in front of the
ankle-joint, and along the dorsum of the foot ; it supplies the inner side of the
great toe, and the adjoining 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 internal saphenous nerve, and joins with the anterior tibial nerve, between
the great and second toes.
The external branch, the larger, passes along the outer side of the dorsum of
the foot, to be distributed to the adjoining sides of the third, fourth, and fifth
toes. It also supplies the integument of the outer ankle and outer side of the
foot, communicating with the short saphenous nerve. The distribution of these
nerves will be found to vary ; together, they supply all the toes excepting the
outer side of the little toe, and the adjoining sides of the great and second toes.
The Sympathetic Nerve.
The Sympathetic Nerve is so called from the opinion entertained that through
it is produced a sympathy between the affections of distant organs. It consists
of a series of ganglia, connected together by intervening cords, extending on each
side of the vertebral column from the base of the skull to the coccyx. It may,
moreover, be traced up into the head, where the ganglia occupy spaces between
the cranial and facial bones. These two gangliated cords lie parallel with one
another as far as the sacrum, on which bone they converge, communicating
together through a single ganglion (ganglion impar), placed in front of the coccyx.
Some anatomists also state that the two cords are joined at their cephalic extremity,
through a small ganglion (the ganglion of Ribes), situated upon the anterior com-
municating artery. Moreover, the chains of opposite sides communicate between
these two extremities in several parts, by means of the nervous cords that arise
from them.
The ganglia are somewhat less numerous than the vertebroB ; thus there are
only three in the cervical region, twelve in the dorsal, four in the lumbar, five in
the sacral, and one in the coccygeal.
The sympathetic nerve, for convenience of description, may be divided into
several parts, according to the position occupied by each ; and the number of
ganglia of which each part is composed may be thus arranged : —
Cephalic portion
4 ganglia.
Cervical "
3 "
Dorsal "
. 12 "
Lumbar "
4 "
Sacral "
5 "
Coccygeal "
1 ganglion
Each ganglion may be regarded as a distinct centre, from or to which branches
pass in various directions. These branches may be thus arranged: — 1. Branches
of communication between the ganglia. 2. Branches of communication with the
cerebral or spinal nerves. 3. Primary branches passing to be distributed to the
arteries in the vicinity of the ganglia, and to the viscera, or proceeding to other
ganglia placed in the thorax, abdomen, or pelvis.
1. The branches of communication between the ganglia are composed of gray
and white nerve fibres, the latter being continuous with those fibres of the spinal
nerves which pass to the ganglia.
2. The branches of communication between the ganglia and the cerebral or
spinal nerves also consist of a white and a gray portion ; the former proceeding
from the spinal nerve to the ganglion, the latter passing from the ganglion to the
spinal nerve.
3. The primary branches of distribution also consist of two kinds of nerve
fibres, the sympathetic and spinal. They have a remarkable tendency to form
intricate plexuses, which encircle the bloodvessels, and are conducted by them to
the viscera. The greater number, however, of these branches pass to a series of
ganglia, or ganglionic masses, of variable size, situated in the large cavities of
the trunk, the thorax, and abdomen ; and are connected with the roots of the great
arteries of the viscera. These ganglia are single and unsymmetrical, and are
called the cardiac and semilunar. From these visceral ganglia numerous plexuses
are derived, which entwine round the bloodvessels, and are conducted by them to
the viscera.
592
SYMPATHETIC NERVE.
593
Fig. 296. — The Sympathetic Nervo.
Suptrinr Curvirnl (Jan^lioM.
^Udells Cervical Ganglion
Inferior Cervical Ganijlion
S.icral Cauirlia
Ciinglioti Impar—-^
laryngeal ZraneJit*
CarJiae 13 r 4
tep Cardiac Plexus
Superficial Cardiac Plexus
Solar Plexum
— ^ Aortic Plexus
llypogaetrie FZexu-B
38
i>9i SYMPATHETIC NERVE.
Cephalic Portion of the Sympathetic.
The cephalic portion of the sympathetic consists of four ganglia. 1. The oph-
thalmic ganglion. 2. The spheno-palatine or Meckel's ganglion. 3. The otic or
Arnold's ganglion. 4. The submaxillary ganglion.
These have been already described in connection with each of the three divi-
sions of the fifth nerve.
Cervical Portion of the Sympathetic.
•
The cervical portion of the sympathetic consists of three ganglia on each side,
which are distinguished according to their position, as the superior, middle, and
inferior cervical.
The Superior Cervical Ganglion, the largest of the three, is placed opposite
the second and third cervical vertebrae, and sometimes as low as the fourth or fifth.
It is of a reddish-gray color, and usually fusiform in shape ; sometimes broad, and
occasionally constricted at intervals, so as to give rise to the opinion, that it con-
sists of the coalescence of several smaller ganglia. It is in relation, in front, with
the sheath of the internal carotid artery, and internal jugular vein ; behind, it
lies on the Eectus capitis anticus major muscle.
Its branches may be divided into superior, inferior, external, internal, and
anterior.
The Superior branch appears to be a direct continuation 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 side, and the other on the inner side, of
that vessel.
The outer branch, the larger of the two, distributes filaments to the internal caro-
tid artery, and forms the Carotid Plexus (described on page 595).
The inner branch also distributes filaments to the internal carotid, and, continu-
ing onwards, forms the Cavernous Plexus (described on page 595).
The Inferior or Descending branch of the superior cervical ganglion communi-
cates with the middle cervical ganglion.
The External branches are numerous, and communicate with the cranial nerves,
and with the four upper spinal nerves. Sometimes, the branch of the fourth spinal
nerve may come from the cord connecting the upper and middle cervical ganglia.
The branches of communication with the cranial nerves consist of delicate filaments,
which pass from the superior cervical ganglion to the ganglion of the trunk of the
pneumogastric, and to the ninth nerve. A separate filament from the cervical
ganglion subdivides and joins the petrosal ganglion of the glosso-pharyngeal, and
the ganglion of the root of the pneumogastric in the jugular foramen.
The Internal branches are three in number: pharyngeal, laryngeal, and the
superior cardiac nerve. The pharyngeal branches pass inwards to the side of the
pharynx, where they join with branches from the pneumogastric, glosso-pharyn-
geal, and external laryngeal nerves, and assist in forming the pharyngeal plexus.
The laryngeal branches unite with the superior laryngeal nerve and its branches.
The superior cardiac nerve will be described in connection with the other cardiac
nerves.
The Anterior branches ramify upon the external carotid artery and its branches,
forming round each a delicate plexus, on the nerves composing which small
ganglia are occasionally found. These ganglia have been named, according to
their position, intercarotid (one placed at the angle of bifurcation of the common
carotid), lingual, temporal, and pharyngeal. The plexuses accompanying some of
these arteries have important communications with other nerves. That sur-
rounding the external carotid is connected with the digastric branch of the facial;
that surrounding the facial communicates with the submaxillary ganglion by one
or two filaments ; and that accompanying the middle meningeal artery sends
CERVICAL GANGLIA. 595
offsets which pass to the otic ganglion and to the intumescentia gangliformis of
the facial nerve.
The Middle Cervical Ganglion (thyroid ganglion) is the smallest of the three
cervical ganglia, and is occasionally altogether wanting. It is placed opposite the
fifth cervical vertebra, usually upon, or close to, the inferior thyroid artery; hence
the name " thyroid ganglion," assigned to it by Haller.
Its superior branches ascend to communicate with the superior cervical
ganglion.
Its inferior branches descend to communicate with the inferior cervical
ganglion.
Its external branches pass outwards to join the fifth and sixth spinal nerve?.
These branches are not constantly found.
Its internal brandies are the thyroid and the middle cardiac nerve.
The thyroid branches are small filaments, which accompany the inferior thyroid
artery to the thyroid gland ; 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 cardiac nerve is described with the other cardiac nerves.
The Inferior Cervical Ganglion is situated between the base of the trans-
verse 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 frequently joined with the first thoracic ganglion.
Its superior branches communicate with the middle cervical ganglion.
Its inferior branches descend, some in front of, others behind, the subclavian
arterv, to join the first thoracic ganglion. The most important of these branches
constitutes the inferior cardiac nerve, to be presently described.
The external branches consist of several filaments, some of which communicate
with the seventh and eighth spinal nerves; others accompany the vertebral
artery along the vertebral canal, forming a plexus round this vessel, supplying
it with filaments, and communicating with the cervical spinal nerves as high as
the fourth.
Carotid and Cavernous Plexuses.
The Carotid Plexus is situated on the outer side of the internal carotid. Fila
ments from this plexus occasionally form a small gangliform swelling on the under
surface of the artery, which is called the carotid ganglion. The carotid plexus
communicates with the Casserian ganglion, with the sixth nerve, and spheno-
palatine ganglion, and distributes filaments to the wall of the carotid artery, and
to the dura mater (Valentin).
The communicating branches with the sixth nerve consist of one or two fila-
ments, which join that nerve as it lies upon the outer side of the internal carotid.
Other filaments are also connected with the Casserian ganglion. The communica-
tion with the spheno-palatine ganglion is effected by the carotid portion of the
Vidian nerve, which passes forwards, through the cartilaginous substance filling
in the foramen lacerum medium, along the pterygoid canal, to the spheno-palatine
ganglion. In this canal it joins the petrosal branch of the Vidian.
The Cavernous Plexus is situated below, and to the inner side of, that part of the
internal carotid, which is placed by the side of the sella Turcica, in the cavernous
sinus, and is formed chiefly by the internal division of the ascending branch from
the superior cervical ganglion. It communicates with the third, fourth, fifth, and
sixth nerves, and with the ophthalmic ganglion, and distributes filaments to the
wall of the internal carotid. The branch of communication with the third nerve
joins it at its point of division ; the branch to the fourth 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 sixth nerve.
The filament of connection with the ophthalmic ganglion arises from the ante-
596 SYMPATHETIC NERVE.
rior part of the cavernous plexus ; it accompanies the nasal nerve, or continues
forwards as a separate branch.
The terminal filaments from the carotid and cavernous plexuses are prolonged
along the internal carotid, forming plexuses which entwine round the cerebral and
ophthalmic arteries ; along the former vessel they may be traced on to the pia mater ;
along the latter, into the orbit, where they accompany each of the subdivisions of
the vessel, a separate plexus passing with the arteria centralis retinas into the
interior of the eyeball.
Cardiac Nerves.
The cardiac nerves are three in number on each side ; — superior, middle, and
inferior, one being derived from each of the cervical ganglia.
The Superior Cardiac nerve (nervus superficialis cordis) arises by two or more
branches from the superior cervical ganglion, 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 the 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, to 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 filaments from the external laryngeal nerve ; lower down, one
or two twigs from the pneumogastric, and, as it enters the thorax, it joins with the
recurrent laryngeal. Filaments from this nerve accompany the inferior thyroid
artery to the thyroid gland.
The left superior cardiac nerve runs by the side of the left carotid artery, and
in front of the arch of the aorta, to the superficial cardiac plexus; it occasionally
passes behind this vessel, and terminates in the deep cardiac ..plexus.
The Middle Cardiac nerve (nervus cardiacus magnus), the largest of the three,
arises from the middle cervical ganglion, or from the interganglionic 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
subclavian artery ; it then descends on the trachea, receives a few filaments from
the recurrent laryngeal nerve, and joins the deep cardiac plexus. In the neck, it
communicates with the superior cardiac and recurrent laryngeal nerves. On the
left 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.
The Inferior Cardiac nerve (nervus cardiacus minor) 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 communi-
cates freely behind the subclavian artery with the recurrent laryngeal and middle
cardiac nerves.
Cardiac and Coronary Plexuses.
The Great or Deep Cardiac Plexus {p>lexus magnus profundus — 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 pneumogastric. The only cardiac nerves
which do not enter into the formation of this plexus are the left superior cardiac
nerve, and the left inferior cardiac branch from the pneumogastric. The branches
derived from the great cardiac plexus form the posterior coronary plexus, and
part of the anterior coronary plexus ; whilst a few filaments proceed to the pul-
monary plexuses, and to the auricles of the heart.
The branches from the right side of this plexus pass some in front of, and othera
THORACIC GANGLIA. 597
behind, the right pulmonary artery ; the former, the more numerous, transmit a
few filaments to the anterior pulmonary plexus, and are continued along the trunk
of the pulmonary artery, to form part of the anterior coronary plexus ; those
behind the pulmonary artery distribute a few filaments to the right auricle, and
form part of the posterior coronary plexus.
The branches from the left side of the cardiac plexus distribute a few filaments
to the left auricle of the heart and the anterior pulmonary plexus, and then pass
on to form the greater part of the posterior coronary plexus, a few branches
passing to the superficial cardiac plexus.
The Superficial {anterior) 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 the right) inferior cardiac branches of the pneu-
mogastric, and by filaments from the deep cardiac plexus. A small ganglion
(cardiac ganglion of Wrisberg) 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 cardiac plexus forms the chief part of the anterior coronary plexus, and
several filaments pass along the pulmonary artery to the left anterior pulmonary
plexus.
The Posterior Coronary plexus is formed chiefly by filaments 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 Anterior Coronary plexus is prolonged chiefly from the superficial cardiac
plexus, but receives filaments from the deep cardiac plexus. Passing forwards
between the aorta and pulmonary artery, it accompanies the right coronary artery
on the anterior surface of the heart.
Valentin has described nervous filaments ramifying under the endocardium;
and Bemak has found, in several mammalia, numerous small ganglia on the cardiac
nerves, both on the surface of the heart and in its muscular substance. The
elaborate dissections lately completed by Dr. Robert Lee have demonstrated with-
out any doubt the existence of a dense mesh of nerves distributed both to the
surface, and in the substance of the heart, having numerous ganglia developed
upon them.
Thoeacic Part of the Sympathetic.
The thoracic portion of the sympathetic consists of a series of ganglia, which
usually correspond in number to that of the vertebrae ; but, from the occasional
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 covered by the
pleura costalis: the last two are, however, anterior to the rest, being placed on
the side of the bodies of the vertebras. The ganglia are small in size, and of a
grayish color. The first, larger than the rest, is of an elongated form, and usually
blended with the last cervical. They are connected together by cord-like pro-
longations from their substance.
The external branches from each ganglion, usually two in number, communicate
with each of the dorsal spinal nerves.
The internal branches from the six upper ganglia are very small, and distribute
filaments to the thoracic aorta and its branches, besides small branches to the
bodies of the vertebras and their ligaments. Branches from the third and fourth
ganglia form part of the posterior pulmonary plexus.
The internal branches from the six lower ganglia are large and white in color ;
they distribute filaments to the aorta, and unite to form the three splanchnic
nerves. These are named, the great, the lesser, and the smallest or renal splanchnic.
The Great Splanchnic nerve is of a white color, firm in texture, and bears a
marked contrast to the ganglionic nerves. It is formed by branches from the
thoracic ganglia between the sixth and tenth, receiving filaments (according to
598 SYMPATHETIC NERYE.
Mr. Beck) from all the thoracic ganglia above the sixth. These roots unite to
form a large round cord of considerable size. It descends obliquely inwards in
front of the bodies of the vertebras along the posterior mediastinum, perforates the
crus of the Diaphragm, and terminates in the semilunar ganglion, distributing
filaments to the renal plexus and supra-renal gland.
The Lesser Splanchnic nerve 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 coeliac plexus. It communicates in the
chest with the great splanchnic nerve, and occasionally sends filaments to the
renal plexus.
The Smallest or Renal Splanchnic nerve arises from the last ganglion, and, piercing
the Diaphragm, terminates in the renal plexus and lower part of the coeliac 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
cervical ganglia, and are distributed to a large and important organ in the thoracic
cavity. The splanchnic nerves, also three in number, are connected probably
with all the dorsal ganglia, and are distributed to important organs in the abdominal
cavity.
The Epigastric or Solar plexus supplies all the viscera in the abdominal cavity.
It consists of a dense network of nerves and ganglia, situated behind the stomach
and in front of the aorta and crura of the Diaphragm. It surrounds the coeliac
axis and root of the superior mesenteric artery, extending downwards as low as
the pancreas, and outwards to the supra-renal capsules. This plexus, and the
ganglia connected with it, receive the great splanchnic nerve of both sides, part
of the lesser splanchnic nerves, and the termination of the right pneumogastric.
It distributes filaments, which accompany, under the name of plexuses, all the
branches from the front of the abdominal aorta.
The semilunar ganglia of the solar plexus, two in number, one on each side,
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 by the side of the coeliac axis and superior mesenteric artery,
close to the supra-renal glands, the one on the right side lying beneath the vena
cava; the upper part of each ganglion is joined by the greater and lesser
splanchnic nerves, and to the inner side of each the branches of the solar plexus
are connected.
From the solar plexus are derived the following : —
Phrenic or diaphragmatic plexus. Supra-renal plexus.
Coeliac plexus. Eenal plexus.
Gastric plexus. Superior mesenteric plexus.
Hepatic plexus. Spermatic plexus.
Splenic plexus. Inferior mesenteric plexus.
The phrenic plexus accompanies the phrenic artery to the Diaphragm, which
it supplies, some filaments passing to the supra-renal gland. It arises from the
upper part of the semilunar ganglion, and is larger on the right than on the left
side. In connection with this plexus, on the right side, at its point of junction
with the phrenic nerve, is a small ganglion (ganglion diaphragmaticum). This
ganglion is placed on the under surface of the Diaphragm, near the supra-renal
gland. Its branches are distributed to the vena cava, supra-renal gland, and the
hepatic plexus. The ganglion is absent on the left side.
The supra-renal plexus is formed by branches from the solar plexus, from the
semilunar ganglion, and from the splanchnic and phrenic nerves, a ganglion being
formed at the point of junction of the latter nerve. It supplies the supra-renal
gland. The branches of this plexus are remarkable for their large size, in com-
parison with the size of the organ they supply.
The renal plexus is formed by filaments from the solar plexus, the oiater part
SOLAR PLEXUS— SEMILUNAR GANGLIA. 599
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, have numerous ganglia developed upon them. They
accompany the branches of the renal artery into the kidney ; some filaments on
the right side being distributed to the vena cava, and others to the spermatic
plexus, on both sides.
The spermatic plexus is derived from the renal plexus, receiving branches from
the aortic plexus. It accompanies the spermatic vessels to the testes.
In the female, the ovarian plexus is distributed to the ovaries and fundus of the
uterus.
The coeliac plexus, of large size, is a direct continuation from the solar plexus :
it surrounds the coeliac axis, and subdivides into the gastric, hepatic, and splenic
plexuses. It receives branches from one or more of the splanchnic nerves, and,
on the left side a filament from the pneumogastric.
The gastric plexus accompanies the gastric artery along the lesser curvature of
the stomach, and joins with branches from the left pneumogastric nerve. It is
distributed to the stomach.
The hepatic plexus, the largest offset from the cceliac plexus, receives filaments
from the left pneumogastric 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 pneumogastric nerves. There is also a
gastro-duodenal plexus, which subdivides into the pancreatico-duodenal plexus,
which accompanies the pancreatico-duodenal artery, to supply the pancreas and
duodenum, joining with branches from the mesenteric plexus; and a gastro-
epiploic plexus, which accompanies the right gastro-epiploic arter3r along the
greater curvature of the stomach, and anastomoses with branches from the splenic
plexus. A cystic plexus, which supplies the gall-bladder, also arises from the
hepatic plexus, near the liver.
The splenic plexus is formed by branches from the right and left semilunar
ganglia, and from the right pneumogastric nerve. It accompanies the splenic
artery and its branches to the substance of the spleen, giving oft) in its course,
filaments to the pancreas (pancreatic plexus), and the left gastro- epiploic plexus,
which accompanies the gastro-epiploica sinistra artery along the convex border of
the stomach.
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 pneumogastric
nerve with the cceliac plexus. It surrounds the superior mesenteric artery, which
it accompanies into the mesentery, and divides into a number of secondary plex-
uses, which are distributed to all the parts supplied by the artery, viz., pan-
creatic 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 great 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 aortic plexus is formed by branches derived, on each side, from the semi-
lunar ganglia and renal plexuses, 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 the in-
ferior mesenteric, part of the spermatic, and the hypogastric plexuses ; and it dis-
tributes filaments to the inferior cava.
The inferior mesenteric plexus is derived chiefly from the left side of the aortic
plexus. It surrounds the inferior mesenteric 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
600 SYMPATHETIC NERYE.
flexure of the colon ; and the superior hemorrhoidal plexus, which supplies the
upper part of the rectum, and joins in the pelvis with branches from the left
hypogastric plexus.
The Lumbar Portion of the Sympathetic.
The lumbar portion of the sympathetic is situated in 'front of the vertebral
column, along the inner margin of the Psoas muscle. It consists usually of four
ganglia, connected together by interganglionic cords. The ganglia aie of small
size, of a grayish color, hordeiform in shape, and placed much nearer the median
line than the thoracic ganglia.
The superior and inferior branches of the lumbar ganglia serve as communicat-
ing branches between the chain of ganglia in this region. They are usually single,
and of a white color.
The external branches communicate with the lumbar spinal nerves. Prom the
situation of the lumbar ganglia, these branches are longer than in the other
regions. They are usually two in number for each ganglion, and accompany the
lumbar arteries around the sides of the bodies of the vertebrae, passing beneath
the fibrous arches from which the fibres of the Psoas muscle partly arise.
The internal branches pass inwards, in front of the aorta, and form the lumbar
aortic plexus (already described). Other branches descend in front of the com-
mon iliac arteries, and join, over the promontory of the sacrum, to form the
hypogastric plexus. Numerous delicate filaments are also distributed to the
bodies of the vertebras and the ligaments connecting them.
Pelvic Portion of the Sympathetic.
The pelvic portion of the sympathetic is situated in front of the sacrum, along
the inner side of the anterior sacral foramina. It consists of four or five small
ganglia on each side, connected together by interganglionic cords. Below, they
converge and unite on the front of the coccyx, by means of a small ganglion
(ganglion impar).
The superior and inferior branches are the cords of communication between the
ganglia above and below.
The external branches, exceedingly short, communicate with the sacral nerves.
They are two in number to each ganglion. The coccygeal nerve communicates
either with the last sacral or the coccygeal ganglion.
The internal branches communicate, on the front of the sacrum, with the
corresponding branches from the opposite side ; some, from the first two ganglia,
pass to join the pelvic plexus, and others form a plexus, which accompanies the
middle sacral artery.
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 aortic plexus, from the lumbar ganglia, and from the first two sacral
ganglia. This plexus contains no ganglia, and bifurcates, below, into two lateral
portions, which form the inferior hypogastric or pelvic plexuses.
Inferior Hypogastric or Pelvic Plexus.
The inferior hypogastric or pelvic plexus is situated at the side of the rectum
and bladder in the male, and at the side of the rectum, vagina, and bladder,
in the female. 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 sacral ganglia. At the point of junction of these nerves, small ganglia
are found. From this plexus numerous branches are distributed to all the viscera
of the pelvis. They accompany the branches of the internal iliac artery.
PELVIC PLEXUS. 601
The inferior 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 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 to the side and base of
the bladder. Numerous filaments also pass to the vesiculas seminales, and vas
deferens ; those accompanying the vas deferens join, on the spermatic cord, with
branches from the spermatic plexus.
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, vesicula3 seminales, and erectile structure of the penis. The nerves sup-
plying the erectile structure of the penis consist of two sets, the small and large
cavernous nerves. They are slender filaments, which arise from the fore part of
the prostatic plexus; and, after joining with branches from the internal pudic
nerve, pass forwards beneath the pubic arch.
The small cavernous nerves perforate the fibrous covering of the penis near
its root.
The large cavernous nerve passes forwards along the dorsum of the penis, joins
with the dorsal branch of the pudic nerve, and is distributed to the corpus caver -
nosum and corpus spongiosum.
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 anterior
part, and to the mucous membrane. The nerves composing this plexus contain,
like the vesical, a large proportion of spinal nerve fibres.
The uterine nerves arise from the lower part of the hypogastric plexus, above
the point where the branches from the sacral nerves join the pelvic plexus. They
accompany the uterine arteries to the side of the organ between the layers of the
broad ligament, 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 Fallopian tube.
Branches from the hypogastric plexus accompany the uterine arteries into the
substance of the uterus. Upon these filaments ganglionic enlargements are found.1
1 Much difference of opinion still exists as to whether the uterine nerves enlarge during preg-
nancy. Dr. Robert Lee states, as the result of a series of elaborate investigations, that the
nerves and ganglia supplying the uterus become greatly enlarged during gestation, thus confirm-
ing the observations previously made by William Hunter, and Tiedemann. Dr. Snow Beck, on
the other hand, asserts that the nerves do not alter in size during pregnancy.
For a detailed account of this subject, the reader should refer to "The Anatomy of the Nerves
of the Uterus," by Robert Lee, M. D., 1841; to two papers by the same author in the Phil.
Trans., for 1842 ; and to Dr. Snow Beck's paper, "On the Nerves of the Uterus," in the Phil.
Trans., for 1846.
Organs of the Senses.
The Organs of the Senses are the instruments by which the mind is brought
into relation with external objects. These organs are five in number, viz., the
organs of touch, of smell, of taste, of hearing, and of sight.
The Skin.
The skin is the principal seat of the sense of touch, and may be regarded as a
covering for the protection of the deeper tissues ; it is also an important excretory
and absorbing organ. It consists of two layers, the derma or cutis vera, and the
epidermis or cuticle. On the surface of the former layer are the sensitive
Fig. 297.— A Sectional View of the Skin (magnified).
1/u.trUat Artery
papillae j and within, or imbedded beneath it, are the sweat-glands, hair-follicles,
and sebaceous glands.
The derma or true skin is tough, flexible, and highly elastic, being admirably
adapted to defend the internal parts from violence. It consists of fibro-areolar
tissue, intermixed with numerous bloodvessels, lymphatics, and nerves. The
fibro-areolar tissue forms the framework of the cutis ; it is composed of firm
602
THE SKIN. 603
interlacing bundles of white fibrous tissue, intermixed with a much smaller pro-
portion of yellow elastic fibres, the amount of which varies in different parts.
The fibro-areolar tissue is more abundant in the deeper layers of the cutis, where
it is dense and firm, the meshes being large, and gradually becoming blended with
the subcutaneous areolar tissue ; towards the surface, the fibres become finer and
more closely interlaced, the most superficial layer being covered with numerous
small, conical, vascular eminences, the papilla?. From these differences in the
structure of the cutis at different parts, it is usual to describe it as consisting of
two layers ; the deep layer or corium, and the superficial or papillary layer.
The corium consists of strong interlacing fibrous bands, composed chiefly of
the white variety of fibrous tissue ; but containing, also, some fibres of the yellow
elastic tissue, which vary in amount in different parts. Towards the attached
surface, the fasciculi are large and coarse ; and the areola? left by their interlacing
large and occupied by adipose tissue and the sweat-glands. This element of
the skin becomes gradually blended with the subcutaneous areolar tissue. Towards
the free surface, the fasciculi are much finer, and they have a closer interlacing,
the most superficial layers consisting of a transparent, homogeneous matrix with
imbedded nuclei.
The corium varies in thickness, from a quarter of a line to a line and a half, in
different parts of the body. Thus, it is thicker in the more exposed regions, as
the palm of the hand and sole of the foot ; on the posterior aspect of the body,
than the front ; and on the outer side of the limbs than the inner. In the eye-
lids, scrotum, and penis, it is exceedingly thin and delicate. The skin generally
is thicker in the male than in the female.
The areolae are occupied by adipose tissue, hair follicles, and the sudatory and
sebaceous glands; they are the channel by which the vessels and nerves are
distributed to the more superficial strata of the corium, and to the papillary
layer.
Plain muscular fibres are found in the superficial layers of the corium, where-
ever hairs are found ; and in the subcutaneous areolar tissue of the scrotum, penis,
perineum, and areolae of the nipple. In the latter situations, the fibres are arranged
in bands, closely reticulated and disposed in superimposed lamina?.
The papillary layer is situated upon the free surface of the corium ; it consists
of numerous small, highly sensitive, and vascular eminences, the papillae, which'
rise perpendicularly from its surface, and form the essential element of the organ
of touch. The papillae are conical-shaped eminences, having a round or blunted
extremity, occasionally divided into two or more parts, and connected by their
base with the free surface of the corium. Their average length is about T^th
of an inch, and they measure at their base about 35 ^th of an inch in diameter.
On the general surface of the body, more especially in those parts which are
endowed with slight sensibility, they are few in number, short, exceedingly minute,
and irregularly scattered over the surface ; but in other situations, as upon the
palmar surface of the hands and fingers, upon the plantar surface of the feet and
toes, and around the nipple, they are long, of large size, closely aggregated
together, and arranged in parallel curved lines, 'forming the elevated ridges seen
on the free surface of the epidermis. In these ridges, the larger papillae are
arranged in a double row, with smaller papillae between them ; and these rows are
subdivided into small square-shaped masses by short transverse furrows regularly
disposed, in the centre of each of which is the minute orifice of the duct of a
sweat-gland. No papillae exist in the grooves between the ridges. In structure
the papillae resemble the superficial layer of the cutis; consisting of a homogeneous
tissue, faintly fibrillated, and containing a few fine elastic fibres. The smaller
papilla? contain a single capillary loop ; but in the larger the vessels are convoluted
to a greater or less degree ; each papilla also contains one or more nerve fibres*
but the mode in which these terminate is uncertain. In those parts in which the
sense of touch is highly developed, as in the lips and palm of the hand, the
nerve fibres appear to have some intimate connection with an oval-shaped body,
604 ORGANS OF THE SENSES.
not unlike a Pacinian corpuscle, which occupies the principal part of the interior
of each papilla, named "tactile corpuscle." The nature of these bodies is obscure.
Wagner described them as oval-shaped bodies, made up of superimposed saccular
laminae, presenting some resemblance to a miniature fir cone, and regarded them as
directly concerned in the sense of touch. Kolliker considers that the central part
of the papillae generally consists of a more homogeneous connective tissue than
the outer part, surrounded by a sort of sheath of elastic fibres, and believes that
these corpuscles are merely a variety of this structure. The nerve fibres, accord-
ing to this observer, run up in a waving course to the corpuscle, not penetrating
it, but forming two or three coils round it, and finally join together in loops.
These bodies are not found in all the papillae ; but from their existence in those
parts in which the skin is highly sensitive, it is probable that they are specially
concerned in the sense of touch, but their absence from the papillae of other
tactile parts shows that they are not essential to this sense. No lymphatics have
as yet been discovered in the papillae.
The epidermis, cuticle, or scarf-skin, is an epithelial structure, accurately moulded
on the papillary layer of the derma. It forms a defensive covering to. the surface
of the true skin, and limits the evaporation of watery vapor from its free surface.
It varies in thickness in different parts. Where it is exposed to pressure and the
influence of the atmosphere, as upon the palms of the hands and soles of the feet,
it is thick, hard, and horny in texture ; whilst that which lies in contact with the
rest of the body is soft and cellular in structure. The deeper and softest layers
have been called the rete mucosum, the term rete being applied, from the deepest
layers presenting, when isolated, numerous depressions, or complete apertures,
which have been occupied by the projecting papillae.
The free surface of the epidermis is marked by a network of linear furrows of
variable size, marking out the surface into a number of spaces of polygonal or
lozenge-shaped form. Some of these furrows are large, as opposite the flexures
of the joints, and correspond to the folds in the derma produced by their move-
ments. In other situations, as upon the back of the hand, they are exceedingly
fine, and intersect one another at various angles ; upon the palmar surface of the
hand and fingers, and upon the sole, these lines are very distinct, and have a
curvilinear arrangement, and depend upon the large size and peculiar arrangement
of the papillae upon which the epidermis is placed. The deep surface of the
epidermis is accurately moulded upon the papillary layer of the derma, each
papilla being invested by its epidermic sheath ; so that when this layer is removed
by maceration, it presents a number of pits or depressions corresponding to the
elevations of the papillae, as well as the furrows left in the intervals between them.
Fine tubular prolongations from this layer are continued into the ducts of the
sudatory and sebaceous glands. In structure, the epidermis consists of flattened
cells, agglutinated together, and having a laminated arrangement. In the deeper
layers the cells are large, rounded or columnar, and filled with soft opaque contents.
In the superficial layers the cells are flattened, transparent, dry, and firm, and
their contents converted into a kind of horny matter. The difference in the
structure of these layers is dependent upon the mode of growth of the epidermis.
As the external layers desquamate, from their being constantly subjected to attri-
tion, they are reproduced from beneath, successive layers gradually approaching
towards the free surface, which, in their turn, die and are cast off.
These cells are developed in the liquor, sanguinis, which is poured out on the
free surface of the derma ; they contain nuclei, and form a thin stratum of closely-
aggregated nucleated cells, which cover the entire extent of the papillary layer.
The deepest layer of cells, according to Kolliker, are of a columnar form, and are
arranged perpendicularly to the free surface of the derma, forming either a single
or a double, or even triple, layer ; the laminae succeeding these are composed of
cells of a more rounded form, the contents of which are soft, opaque, granular, and
soluble in acetic acid. As these cells successively approach the surface by the
development of fresh layers from beneath, they assume a flattened shape from the
APPENDAGES OF THE SKIN. 605
evaporation of their fluid contents, and finally form a transparent, dry, mem-
branous scale, lose their nuclei, and apparently become changed in their chemical
composition, as they are unaffected now by acetic acid.
The black color of the skin in the negro, and the tawny color among some of
the white races, is due to the presence of pigment in the cells of the cuticle.
This pigment is more especially distinct in the cells of the deeper layer or rote
mucosum, and is similar to that found in the choroid. As the cells approach the
surface and desiccate, the color becomes partially lost.
The arteries which supply the skin divide into numerous branches in the sub-
cutaneous tissue ; they then pass through the areola? of the corium, and divide
into a dense capillary plexus, which supplies the sudatory and sebaceous glands
and the hair follicles, terminating in the superficial layers of the corium, by form-
ing a capillary network, from which numerous fine branches ascend to the papilla?.
The lymphatic vessels are arranged in a minute plexiform network in the
superficial layers of the corium, where they become interwoven with the capillary
and nervous plexuses ; they are especially abundant in the scrotum and round
the nipple.
The nerves which supply the skin ascend with the vessels through the areola?
of the deep layers of the corium to the more superficial layers, where they form
a minute plexiform mesh. From this plexus, the primitive nerve fibres pass to
be distributed to the papilla?. The nerves are most numerous in those parts which
are provided with the greatest sensibility.
Appendages of the Skin.
The appendages of the skin are, the nails, the hairs, the sudoriferous and
sebaceous glands, and their ducts.
The nails and hairs are peculiar modifications of the epidermis, consisting
essentially of the same cellular structure as that membrane.
The Nails are flattened 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 surface, concave within, and is implanted by a portion called
the root into a groove of the skin; the exposed portion is called the body, and the
anterior extremity, the free edge. The nail has a very firm adhesion to the cutis,
being accurately moulded upon its surface, as the epidermis is in other parts.
The part of the cutis beneath the body and root of the nail is called the matrix,
from its being the part from which the nail is produced. Corresponding to the body
of the nail, the matrix is thick, and covered with large highly vascular papilla?,
arranged in longitudinal rows, the color of which is seen through the transparent
tissue. Behind this, near the root of the nail, the papilla? are small, less vascular,
and have no regular arrangement ; hence the portion of the nail corresponding
to this part is of a whiter color, and called lunula from its form.
The cuticle, as it passes forwards on the dorsal surface of the finger, is attached
to the surface of the nail, a little in advance of its 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 horny structure of the nail, both epidermic structures, are thus
seen to be directly continuous with each other. The nails, in structure, consist of
cells having a laminated arrangement, and these are almost essentially similar to
those composing the epidermis. The deepest layer of cells which lie in contact
with the papilla? at the root and under surface of the nail, are of elongated form,
arranged perpendicularly to the surface, and provided with nuclei ; those which
succeed these are of a rounded or polygonal form, the more superficial ones
becoming broad, thin, and flattened, and so closely compacted together as to make
the 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 forwards, and maintains a due thickness, whilst,
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 cells, they assume
606 . ORGANS OF THE SENSES.
a flattened form, lose their nuclei, and finally become closely compacted together
into a firm, dense, horny texture. In chemical composition, the nails resemble the
epidermis. According to Mulder, they contain a somewhat larger proportion of
carbon and sulphur.
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 pa*lms of the hands and soles of the feet, and
vary much in length, thickness, and color in different parts of the body, and in
the different races of mankind. In some parts they are so short as not to project
beyond the follicle containing them ; in other parts, as upon the scalp, they are of
considerable Jength ; along the margin of the eyelids and upon the face, they are
remarkable for their thickness. A hair consists of a root, the part implanted in
the skin ; the shaft, the portion projecting from its surface ; and the point. They
generally present a cylindrical or more or less flattened form, and a reniform out-
line upon a transverse section.
The root of the hair presents a bulbous enlargement at its extremity ; it is
whiter in color, and softer in texture, than the stem, and is lodged in a follicular
involution of the epidermis, called the hair-follicle. When the hair is of con-
siderable length, the follicle extends into the subcutaneous cellular tissue. The
hair-follicle is bulbous at its deep extremity, like the hair which it contains, and
has opening into it, near its free extremity, the orifices of the ducts of one or more
sebaceous glands. In structure, the hair-follicle consists of two coats : an outer
or dermic, and an inner or cuticular. The outer coat is formed mainly of areolar
tissue; it is continuous with the corium, is highly vascular, and supplied by
numerous minute nervous filaments. The inner or cuticular lining is continuous
with the epidermis, and, at the bottom of the hair-follicle, with the root of the hair ;
this cuticular lining resembles the epidermis in the peculiar rounded form and soft
character of those cells which lie in contact with the outer coat of the hair-follicle,
and the thin, dry, and scaly character of those which lie near the surface of the
hair, to which they are closely adherent. "When the hair is plucked from its
follicle, this cuticular lining most commonly adheres to it, and forms what is called
the root-sheath. At the bottom of each hair-follicle is a small conical-shaped
vascular eminence or papilla, similar in every respect to those found upon the
surface of the skin; it is continuous with the dermic layer of the follicle, is highly
vascular, and probably supplied with nervous fibrils : this is the part through
which material is supplied for the production and constant growth of the hair.
The root of the hair rests upon this conical-shaped eminence, and is continuous
with the cuticular lining of the follicle at this part. It consists of nucleated cells,
similar in every respect to those which in other situations form the epidermis.
These cells gradually enlarge as they are pushed upwards into the soft bulb, and
some of them contain pigment granules, which exist either in separate cells, or
the granules are separate, but aggregated round the nucleus ; it is these granules
which give rise to the color of the hair. It occasionally happens that these
pigment granules completely fill the cells 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 shaft of the hair consists of a central part or medulla ; surrounding this is
the fibrous part of the hair, covered externally by the cortex. The medulla
occupies the centre of the shaft, and ceases towards 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 more opaque and deeper colored than the fibrous part,
and consists of cells containing pigment or fat-granules. The fibrous portion of
the hair constitutes the chief part of the stem ; its cells are elongated, and unite
to form flattened fusiform fibres. These also contain pigment granules, which
assume a linear arrangement. The cells which form the cortex of the hair consist
of a single layer which surrounds those about to form the fibrous layer ; they arc
converted into thin flat scales, having an imbricated arrangement.
APPENDAGES OF THE SKIN. 607
The Sebaceous Glands are small, sacculated, glandular organs, lodged in the
substance of the corium or sub-dermoid tissue. They are found in most parts of
the skin, but are most 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 the soles of the feet. Each gland consists of a
single duct, more or less capacious, which terminates in a lobulated pouch-like
extremity. The basement membrane forming the wall of the sac, as well as the
duct, is lined by epithelium, which is filled with particles of sebaceous matter ;
and this becoming detached into the cavity of the sac, as its growth is renewed,
constitutes the secretion. The number of sacculi connected with each duct vary
from two to five, or even twenty, in number. The orifices of the ducts open most
frequently into the hair-follicles, but occasionally upon the general surface. 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 eyelid, the Meibomian glands.
The Sudoriferous or Sweat-glands are the organs by which a large portion of
the aqueous and gaseous materials are excreted by the skin. They are found in
almost every part of the skin, and are situated in small pits in the deep parts of
the corium, or in the subcutaneous areolar tissue, surrounded by a quantity
of adipose tissue. They are small, lobular, reddish bodies, consisting of one or
more convoluted tubuli, from which the efferent duct proceeds upwards through
the corium and cuticle, and opens upon the surface by a slightly enlarged orifice.
The efferent duct, as it passes through the corium, pursues, for a short distance, a
spiral course, becoming straight in the more superficial part of this layer, and
opens on the surface of the cuticle by an oblique valve-like aperture. In the
parts where the epidermis is thin, the ducts are finer and almost straight in their
course ; but where the epidermis is thicker, they assume again a spiral arrange-
ment, the separate windings of the tube being as close and as regular as those of
a common screw. 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 these glands
varies. They are especially large in those regions where the amount of perspira-
tion is great, as in the axillae, where they form a thin mammillated 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, and present, according to Krause, 2,800
orifices on a square inch of the integument, and a rather less number on the sole
of the foot. In both of these situations, the orifices of the ducts are exceedingly
regular, and correspond to the small transverse grooves which intersect the ridges
of papillae. In other situations they are more irregularly scattered, but in nearly
equal numbers over parts including the same extent of surface. 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 ?'5 of a line in
diameter, he calculates that the whole of these glands would present an evaporat-
ing surface of about eight square inches.
Each gland consists of a single tube intricately convoluted, at one end termi-
nating by a blind extremity ; at the other end opening upon the surface of the
skin. In the larger glands, this single duct usually divides and subdivides
dichotomously ; the smaller ducts ultimately terminating in short caecal pouches,
rarely anastomosing. The wall of the duct is thick ; the width of the canal rarely
exceeding one-third of its diameter. The tube, both in the gland and where it
forms the excretory duct, consists of two layers : an outer, formed by fine areolar
tissue ; and an epithelium lining its interior. The external or fibro-cellular coat
is thin, continuous with the superficial layer of the corium, and extends only as
high as the surface of the true skin. The epithelial lining is much thicker, con-
tinuous with the epidermis, and alone forms the spiral portion of the tube. When
the cuticle is carefully removed from the surface of the cutis, these convoluted
G08
ORGANS OF THE SENSES.
tubes of epidermis may be drawn out, and form nipple-shaped projections on its
under surface. According to Kolliker, a layer of non-striated muscular fibres,
arranged longitudinally, is found between the areolar and epithelial coats of the
ducts of the larger sweat-glands, as in the axilla, root of the penis, on the labia
majora, and around the anus.
The contents of the smaller sweat-glands are quite fluid ; but in the larger
glands, the contents are semi-fluid and opaque, and contain a number of colored
granules, and cells which appear analogous to epithelial cells.
The Tongue.
The tongue is the organ of the special sense of taste. It is situated in the
floor of the mouth, in the interval between the two lateral portions of the body of
Fig. 298. — Upper Surface of the Tongue.
Tiliform
-4 ]i e *
FIC.299. The 3 hinds ef PAPILLA magnified
ha tulle*
CtrrinnTitFTrtt*
the lower jaw. Its base or root is directed backwards, and connected with the
os hyoides by numerous muscles, to the epiglottis by three folds of mucous mem-
brane, which form the glosso-epiglottic ligaments, and to the soft palate and
pharynx by means of the anterior and posterior pillars of the fauces. Its apex
THE TONGUE. 609
or tip, thin and narrow, is directed forwards against the inner surface of the
lower incisor teeth. The under surface of the tongue is connected with the
lower jaw by the Genio-hyo-glossi muscles; from its sides, the mucous mem-
brane is reflected to the inner surface of the gums ; and, in front, a distinct fold
of that membrane, the fraenum linguae, is formed beneath its under surface.
The tip of the tongue, part of its under surface, its sides, and dorsum, are free.
The dorsum of the tongue is convex, marked along the middle line by a raphe,
which divides it into two symmetrical halves ; and this raphe terminates behind,
about half an inch from the base of the organ, a little in front of a deep mucous
follicle, the foramen csecum. The anterior two-thirds of this surface are rough,
and covered with papillae ; the posterior third is more smooth, and covered by the
projecting orifices of numerous muciparous glands.
The mucous membrane invests the entire extent of the free surface of the
tongue. On the under surface of the organ it is thin and smooth, and may be
traced on either side of the fraenum, through the ducts of the submaxillary glands ;
and between the sides of the tongue and the lower jaw, through the ducts of the
sublingual glands. On being traced over the borders of the organ, it gradually
assumes its papillary character.
The mucous membrane of the tongue consists of structures analogous to those
of the skin, namely, a cutis or corium, supporting numerous papillse, and covered,
as well as the papillae, with epithelium.
The cutis is tough, but thinner and less dense than in most parts of the skin,
and is composed of similar tissue. It contains the ramifications of the numerous
vessels and nerves from which the papillae are supplied, and affords insertion to
all the intrinsic muscular fibres of the organ.
The papillae of the tongue are thickly distributed over the whole of its upper
surface, giving to it its characteristic roughness. They are more prominent than
those of the skin, which is chiefly due to their not being concealed under the
epithelium, but from their standing out prominently from the surface like the villi
of the intestine. The principal varieties are the papillae maximae (circumvallatae),
papillae mediae (fungiformes), and papillae minimae (conicae and filiformes).
The papillse maximse (circumvallatae) are of large size, and vary from eight to
ten in number. They are situated at the back part of the dorsum of the tongue,
near its base, forming a row on each side, which, running backwards and inwards,
meet in the middle line, like the two lines of the letter A inverted. Each papilla
consists of a central flattened projection of mucous membrane, circular in form,
from 2'jj to ^ of an inch wide, attached to the bottom of a cup-shaped depression
of the mucous membrane ; the exposed part being covered with numerous small
papillae. The cup-shaped, depression forms a kind of fossa round the papilla,
having a circular margin of about the same elevation, covered with smaller papillae.
The fissure corresponding to the papilla, where the two lines of the circum vallate
papillae meet, is so large and deep, that the name foramen csecum has been applied
to it. In the smaller papillae, the fissure exists only on one side.
The papillse medise (fungiformes), 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 attachment to the tongue, but broad and rounded at their free extremities,
and covered with secondary papillae. Their epithelium investment is very thin.
The papillse minimse (conicae et filiformes) 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, excepting at the apex of the organ, where their direction
is transverse. The filiform papillae are of a whitish tint, owing to the thickness
and density of their epithelium; they are covered with numerous secondary
papillae, are firmer and more elastic than the papillae of mucous, membrane
generally, and often inclose minute hairs.
39
610 ORGANS OF THE SENSES.
Simple papillse, similar to those of the skin, are dispersed very unequally
among the compound forms, and exist sparingly on the surface of the tongue
behind the circumvallate variety, buried under a layer of epithelium.
Structure of the papillse. The papillae, in structure, apparently resemble those
of the cutis, consisting of a cone-shaped projection of homogeneous tissue,
covered with a thick layer of squamous epithelium, and contain one or more
capillary loops, amongst which nerves are distributed in great abundance. If the
epithelium is removed it will be found that they are not simple processes like the
papillae of the skin, for, according to Todd and Bowman, the surface of each is
studded with minute conical processes of the mucous membrane, which form
secondary papillae. 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 network, from which brush-like branches proceed; in the papillae
flliformes, their mode of termination is uncertain.
Besides the papillae, the mucous membrane of the tongue is provided with
numerous follicles and glands.
The follicles are found scattered over its entire surface, but are especially
numerous between the papillae circumvallatae and the epiglottis.
The mucous glands (lingual), similar in structure to the labial and buccal, are
found chiefly beneath the mucous membrane of the posterior third of the dorsum
of the tongue. There is a small group of these glands beneath the tip of the
tongue, a few along the borders of the organ, and some in front of the circum-
vallate papillae projecting into the muscular substance. Their ducts open either
upon the surface, or into the depressions round the large papillae.
The epithelium is of the scaly variety like that of the epidermis. It covers the
free surface of the tongue, as may be easily demonstrated by maceration, or boiling,
when it can be detached entire, but it is much thinner than in the skin, the inter-
vals between the large papillae not being 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 these never
contain coloring matter.
The tongue consists of two symmetrical halves, separated from each other, in
the middle line, by a fibrous septum. Each half is composed of muscular fibres
arranged in various directions, containing much interposed fat, and supplied
by vessels and nerves ; the entire organ is invested by mucous membrane, and a
submucous fibrous stratum. The latter membrane invests the greater part of the
surface of the tongue, and into it the muscular fibres are inserted that pass to the
surface. It is thicker behind than in front, and is continuous with the sheaths of
the muscles attached to it.
The fibrous septum consists of a vertical layer of fibrous tissue, extending
throughout the entire length of the middle line of the tongue, from the base to
the apex. It is thicker behind than in front, and occasionally contains a small
fibro-cartilage, about a quarter of an inch in length. It is well displayed by
making a vertical section through the organ. Another strong fibrous lamina,
termed the hyo-glossal membrane, 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 fibres of the Genio-hyo-glossi.
Each half of the tongue consists of extrinsic aud intrinsic muscles. The former
have been already described ; they are the Hyo-glossus, Genio-hyo-glossus, Stylo-
glossus, Palato-glossus, and part of the Superior constrictor. The intrinsic mus-
cles are the Superior longitudinal, Inferior longitudinal, and Transverse.
The superior longitudinal fibres {lingualis superficialis) form a superficial
stratum of oblique and longitudinal fibres on the upper surface of the organ,
beneath the mucous membrane, and extend from the apex backwards to the hyoid
bone, the individual fibres being attached in their course to the submucous and
glandular structures.
The inferior longitudinal fibres are formed by the Lingualis muscle, already
described (p. 261).
THE NOSE. 611
The transverse fibres are placed between the two preceding layers ; they are
intermixed with a considerable quantity of adipose substance, and form the chief
part of the substance of the organ. They are attached internally to the median
fibrous septum ; and, passing outwards, the posterior ones taking an arched course,
are inserted into the dorsum and margins of the organ, intersecting the other
muscular fibres.
The arteries of the tongue are supplied from the lingual, the facial, and ascending
pharyngeal.
The nerves of the tongue are three in number in each half; the gustatory
branch of the fifth, which is distributed to the papilla? at the fore part and sides
of the tongue ; the lingual branch of the glosso-pharyngeal, which is distributed
to the mucous membrane at the base and side of the tongue, and to the papilla)
circumvallatse ; and the hypoglossal nerve, which is distributed to the muscular
substance of the tongue. The two former are nerves of common sensation and
of taste ; the latter is the motor nerve of the tongue.
The Nose.
The Nose is the special organ of the sense of smell ; by means of the peculiar
properties of its nerves, it protects the lungs from the inhalation of deleterious
gases, and assists the organ of taste in discriminating the properties of food.
The organ of smell consists of two parts, one external, the nose ,- the other
internal, the nasal fossae.
The nose is the more anterior and prominent part of the organ of smell. It is
of a triangular form, directed vertically downwards, and projects from the centre
of the face, immediately above the upper lip. Its summit or root is connected
directly with the forehead. Its inferior part, the base of the nose, presents two
elliptical orifices, the nostrils, separated from each other by an antero-posterior
septum, the columna. The margins of these orifices are provided with a number
Figs. 299, 300.— Cartilages of the Nose.
Seen from I el our JfM St J*- Vic us
otL-crLalwal C,
'esauiola C
of stiff hairs or vibrissse which arrest the passage of foreign substances carried
with the current of air intended for respiration. The lateral surfaces of the nose
form, by their union, the dorsum, the direction of which varies considerably in
different individuals. The dorsum terminates below in a rounded eminence, the
lobe of the nose.
612
ORGANS OF THE SENSES.
Fig. 301.
-Bones and Cartilages of Septum of Nose.
Right Side.
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 supplied with vessels and nerves.
The bony framework occupies the upper part of the organ ; it consists of the
nasal bones, and the nasal processes of the superior maxillary.
The cartilaginous framework consists of five pieces, the two upper and the two
lower lateral cartilages, and the cartilage of the septum.
The upper lateral cartilages are situated below the free margin of the nasal
bones ; each cartilage is flattened, and triangular in shape. Its anterior margin is
thicker than the posterior, and connected with the fibro-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 outwards, the other inwards towards the
nasal cavity.
The lower lateral cartilages are two thin, flexible plates, situated immediately
below the preceding, and curved
in such a manner as to form the
inner and outer walls of each
orifice of the nostril. The por-
tion which forms the inner wall,
thicker than the rest, is loosely
connected with the same part of
the opposite cartilage, and forms
a small part of the columna. Its
outer extremity, free, rounded,
and projecting, forms, with the
thickened integument and sub-
jacent tissue, the lobe of the
nose. The part which forms the
outer wall 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, cartilagines minores or sesamoid cartilages.
Above, it is connected to the upper lateral cartilage and front part of the cartilage
of the septum ; below, it is separated from the margin of the nostril by dense
cellular tissue ; and in front, it forms, with its fellow, the prominence of the tip of
the nose.
The cartilage of the septum is somewhat triangular in form, thicker at its mar-
gins than at its centre, and completes the separation between the nasal fossoe in
front. Its anterior margin, thickest above, is connected from above downwards
with the nasal bones, the front part of the two upper lateral cartilages, and the
inner portion of the two lower lateral cartilages. Its posterior margin is con-
nected with the perpendicular lamella of the ethmoid ; its inferior margin with
the vomer and palate processes of the superior maxillary bones.
These various cartilages are connected to each other, and to the bones, by a
tough fibrous membrane, the perichondrium, which allows the utmost facility of
movement between them.
The muscles of the nose are situated immediately beneath the integument ; they*
are (on each side) the Pyramidalis nasi, the Levator labii superioris alasque nasi,
the Dilator naris anterior, and Dilator naris posterior, the Compressor naris, the
Compressor narium minor, and the Depressor alee nasi (see p. 246).
The integument covering the dorsum and sides of the nose is thin, and loosely
connected with the subjacent parts; but where it forms the tip or lobe and the
NASAL FOSSAE. 613
alae of the nose, it is thicker, and more firmly adherent. It is furnished with a
large number of sebaceous follicles, the orifices of which are usually very distinct.
The mucous membrcme lining the interior of the nose is continuous with the
skin externally, and with that which lines the nasal fossa} within.
The arteries of the nose are the lateralis nasi from the facial, and the nasal
artery of the septum from the superior coronary, which supplies the alae and
septum; the sides and dorsum being supplied from the nasal branch of the
ophthalmic and infra-orbital.
The veins of the nose terminate in the facial and ophthalmic.
The nerves of the nose are branches from the facial, infra-orbital, and infra-
trochlear, and a filament from the nasal branch of the ophthalmic.
Nasal Fossjs.
The Nasal Fossae are two irregular cavities, situated in the middle of the face,
and extending from before backwards. They open in front by the two anterior
nares, and terminate behind in the pharynx, by the posterior nares. The
boundaries of these cavities, and the openings which are connected with them,
as they exist in the skeleton, have been already described (p. 109).
The mucous membrane lining the nasal fossae is called pituitary, from the
nature of its secretion, or Schneiderian 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 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 mastoid cells, through the Eustachian
tube; and with the frontal, ethmoidal, and sphenoidal sinuses, and the antrum
maxillare, 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
maxillare, it is thin and pale.
The surface of the membrane is covered with a layer of tessellated epithelium,
at the upper part of the nasal fossae, corresponding with the distribution of the
olfactory nerve, but ciliated throughout the rest of its extent, excepting near the
aperture of the nares.
This membrane is also provided with a nearly continuous layer of branched
mucous glands, the ducts of which open upon its surface. They are most nume-
rous at the middle and back parts of the nasal fossae, and largest at the lower and
back part of the septum.
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 circumstance, also, the
various apertures communicating with the meatuses are either narrowed or
completely closed.
In the superior meatus, the aperture of communication with the posterior
ethmoidal cells is considerably diminished in size, and the spheno-palatine foramen
completely covered in.
In the middle meatus, the opening of the infundibulum is partially hidden by
a projecting fold of mucous membrane, and the orifice of the antrum is contracted
to a small circular aperture, much narrower than in the skeleton.
In the inferior meatus, the orifice of the nasal duct is partially hidden by either
a single or double valvular mucous fold, and the anterior palatine canal either
complete^ closed in, or a tubular cul-de-sac of mucous membrane is continued a
short distance into it.
614
ORGANS OF THE SENSES.
In the roof, the opening leading to the sphenoidal sinus is narrowed, and the
apertures in the cribriform plate of the ethmoid completely closed in.
The arteries of the nasal fossse 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 maxillary, which supplies the mucous
membrane covering the spongy bones, the meatuses, and septum ; and the alveolar
branch of the internal maxillary, which supplies 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 fossse form a close network beneath the mucous mem-
brane. They pass, some with the veins accompanying the spheno-palatine artery,
through the spheno-palatine foramen ; and others, through the alveolar branch,
join the facial vein; some accompany the ethmoidal arteries, and terminate in the
ophthalmic vein ; and, lastly, a few communicate with the veins in the interior
of the skull, through the foramina in the cribriform plate of the ethmoid bone.
The nerves are the olfactory,
Fig. 303.— Nerves of Septum of Nose. Right Sid,e. faQ nasal branch of the ophthal-
mic, filaments from the anterior
dental branch of the superior
maxillary, the Vidian, naso-pala-
tine, descending anterior palatine,
and spheno-palatine branches of
Meckel's ganglion.
The olfactory, the special nerve
of the sense of smell, is distri-
buted over the upper third of the
septum, and over the surface of
the superior and middle spongy
bones.
The nasal branch of the oph-
thalmic distributes filaments to
the upper and anterior part 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 nasopalatine nerve supplies the middle of the septum.
The larger or anterior palatine nerve supplies the middle and lower spongy
bones.
The Eye.
The eyeball is contained in the cavity of the orbit. In this situation it is
securely protected from injury, whilst its position is such as to insure the most
extensive range of sight. It is acted upon by numerous muscles, by which it is
capable of being directed to any part, is supplied by vessels and nerves, and is
additionally protected in front by several appendages, such as the eyebrow,
eyelids, etc.
The eyeball is spherical in form, having the segment of a smaller and more
prominent sphere engrafted upon its anterior part. It is from this circumstance,
that the antero-posterior diameter of the eyeball, which measures about an inch,
exceeds the transverse diameter by about a line. The segment of the larger
sphere, which forms a"bout five-sixths of the globe, is opaque, and formed by the
sclerotic, the tunic of protection to the eyeball ; the smaller sphere, which forms
the remaining sixth, is transparent, and formed by the cornea. The axes of the
THE EYE,
615
eyeballs are nearly parallel, and do not correspond to the axes of the orbits, which
are directed outwards. The optic nerves follow the direction of the axes of the
orbits, and enter the eyeball a little to their inner or nasal side. The eyeball is
composed of several investing tunics, and of fluid and solid refracting media,
called humors.
The tunics are three in number : —
1. Sclerotic and Cornea.
2. Choroid, Iris, and Ciliary Processes.
3. Eetina.
The refracting media or humors are also three : —
Aqueous. Crystalline (lens) and Capsule. Yitreous.
The sclerotic and cornea form the most external tunic of the eyeball ; they are
essentially fibrous in structure, the sclerotic being opaque, and forming the pos-
terior five-sixths of the globe ; the cornea, which forms the remaining sixth, being
transparent.
Tunics of the Eye.
scleeotic and cornea.
The Sclerotic (axxfaoc, hard) has received its name from its extreme density
and hardness ; it is a firm, unyielding, fibrous membrane, serving to maintain the
peculiar form of the globe (fig. 303). It is much thicker behind than in front.
Fig. 303.— A Vertical Section of the Eyeball. (Enlarged.)
Sclerotic _
Choroid •
Retina ■
Tendon of rectus
Hyaloid Mrmbrane
Ciliary Muscle
£= Ligament
Circular Sinua
anal of Petit
Its external surface is of a white color, quite smooth, except at the points
where the Recti and Obliqui muscles are inserted into it, and covered, for part of
its extent, by the conjunctival membrane ; hence the whiteness and brilliancy of
the front of the eyeball. Its inner surface is stained of a brown color, marked
by grooves, in which are lodged the ciliary nerves, and connected by an exceedingly
fine cellular tissue {lamina fused) with the outer surface of the choroid. Behind,
it is pierced by the optic nerve a little to its inner or nasal side, and is continuous
with its fibrous sheath, which is derived from the dura mater. At the point where
the optic nerve passes through the sclerotic, this membrane forms a thin cribriform
616 ORGANS OF THE SENSES.
lamina {lamina cribrosa); the minute orifices in this part serve for the trans-
mission of the nervous filaments, and the fibrous septa dividing them from one
another are continuous with the membranous processes which separate the bundles
of nerve fibres. One of these openings, larger than the rest, occupies the centre
of this lamellae ; it is called the porus opticus, and transmits the arteria centralis
retinas to the interior of the eyeball. Around the cribriform lamella are numerous
smaller apertures for the transmission of the ciliary vessels and nerves. In
front, this membrane is continuous with the cornea by direct continuity of tissue ;
but the opaque sclerotic overlaps it rather more on its outer than upon its inner
surface.
Structure. The sclerotic is formed of white fibrous tissue intermixed with the
elastic fibres, and fusiform nucleated cells. These are aggregated into bundles,
which are arranged chiefly in a longitudinal direction. It yields gelatin on
boiling. Its vessels are not numerous, the capillaries being of small size, uniting
at long and wide intervals. The existence of nerves in it is doubtful.
The Cornea is the projecting transparent part of the external tunic of the eye-
ball, and forms the anterior sixth of the globe. Its form is not quite circular,
being a little broader in the transverse than in the vertical direction, in conse-
quence of the sclerotic overlapping the margin above and below. It is concavo-
convex, and projects forwards from the sclerotic in the. same manner that a watch-
glass does from its case. Its degree of curvature varies in different individuals,
and in the same individual at different periods of life, being more prominent in
youth than in advanced life, when it becomes flattened. This difference in the
greater or smaller convexity of the cornea influences considerably the refractive
power of the eye, and is the chief cause of the long or short sight peculiar to
different individuals. It is dense and of uniform thickness throughout, its pos-
terior surface is perfectly circular in outline, and exceeds the anterior surface
slightly in extent, from the latter being overlapped by the sclerotic.
Structure. The cornea consists of five layers : a thick central fibrous structure,
the cornea proper ; in front of this the anterior elastic lamina, covered by the con-
junctiva ; behind, the posterior elastic lamina, covered by the lining membrane
of the anterior chamber of the eyeball.
The proper substance of the cornea is fibrous, tough, unyielding, perfectly
transparent, and continuous with the sclerotic, with which it is in structure
identical. The anastomosing fusiform cells of which it is composed are arranged
in superimposed flattened laminae, at least sixty in number, all of which have the
same direction, the contiguous laminae becoming united at frequent intervals.
If the relative position of the component parts of this tissue is in any way altered,
either by pressure or by an increase of its natural tension, it immediately presents
an opaque milky appearance. The interstices between the laminae are tubular,
and usually contain a small amount of transparent fluid.
The anterior and posterior elastic laminse, which cover the proper structure of
the cornea behind and in front, present an analogous structure. They consist
of a hard, elastic, and perfectly transparent homogeneous membrane, of extreme
thinness, which is not rendered opaque by either water, alcohol, or acids. This
membrane is intimately connected by means of a fine cellular web to the proper
substance of the cornea both in front and behind. 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 permanent correct curvature of the flaccid cornea
proper."
The conjunctival epithelium, which covers the front of the anterior elastic
lamina, consists of two or three layers of transparent nucleated cells, the deepest
being of an oblong form and placed perpendicular to the surface, the superficial
ones more flattened.
The epithelial lining of the aqueous chamber covers the posterior surface of the
CORNEA— CHOROID. 617
posterior elastic lamina. It consists of a single layer of polygonal transparent
nucleated cells, similar to those found lining other serous cavities.
Arteries and Nerves. The cornea is a non-vascular structure, the capillary
vessels terminating in loops at its circumference. Lymphatic vessels have not
as yet been demonstrated in it. The nerves are numerous, twenty or thirty in
number : they are derived from the ciliary nerves, and enter the laminated sub-
stance of the cornea. They ramify throughout its substance in a delicate net-
work.
Dissection. In order to separate the sclerotic and cornea, so as to expose the second tunic,
the eyeball should be immersed in water contained in a small vessel. A fold of the sclerotic
near its anterior part having been pinched up, an operation not easily performed from the ex-
treme tension of the membrane, it should be divided with a pair of blunt-pointed scissors. As
soon as the choroid is exposed, the end of a blowpipe should be introduced into the orifice, and
a stream of air forced into it, so as to separate the slight cellular connection between the sclerotic
and choroid. The sclerotic should now be divided around its entire circumference, and may be
removed in separate portions. The front segment being then drawn forwards, the handle of the
scalpel should be pressed gently against it at its connection with the iris, and, these being sepa-
rated, a quantity of perfectly transparent fluid will escape ; this is the aqueous humor. In the
course of the dissection, the ciliary nerves may be seen lying in the loose cellular tissue between
the choroid and sclerotic, or contained in delicate grooves on the inner surface of the latter
membrane.
Fig. 304.— The Choroid and Iris. (Enlarged.)
Choroid, Iris, and Ciliary Processes.
The second tunic is formed by the choroid behind ; the iris and ciliary pro-
cesses in front ; and by the ciliary ligament, and Ciliary muscle, at the point of
junction of the sclerotic and cornea.
The Choroid is the vascular and pigmentary tunic of the eyeball, investing the
posterior five-sixths of the globe, and extending as far forwards as the cornea ;
the Ciliary Processes being appendages of the choroid developed from its inner
surface in front. The Iris is the circular-shaped muscular septum, which hangs
vertically behind the cornea, presenting in its centre a large circular aperture,
the pupil. The ciliary ligament and Ciliary muscle form the white ring observed
at the point where the choroid and iris join with each other, and with the sclerotic
and cornea.
618 ORGANS OF THE SENSES.
The Choroid is a thin, highly vascular membrane, of a dark brown or chocolate
color, which invests the posterior five-sixths of the central part of the globe. It
is pierced behind by the optic nerve, and terminates in front at the ciliary ligament,
where it bends inwards, and forms on its inner surface a series of folds or plaitings,
the ciliary processes. It is thicker behind than in front. Externally, it is con-
nected by a fine cellular web (membrana fused) with the inner surface of the
sclerotic. Its inner surface is smooth, and lies in contact with the retina. The
choroid is composed of three layers, external, middle, and internal.
Fig. 305.— The Veins of the Choroid. (Enlarged.)
The external layer consists of the larger branches of the short ciliary arteries,
which run forwards between the veins before they bend downwards to terminate
on the inner surface. This coat consists, however, principally of veins, which
are disposed in curves ; hence their name, vense vorticosse. They converge to four
or five equidistant trunks, which pierce the sclerotic midway between the margin
of the cornea and the entrance of the optic nerve. Interspersed between the
vessels, are lodged dark star-shaped pigment cells, the fibrous offsets from which,
communicating with similar branches from neighboring cells, form a delicate
network, which, towards the inner surface of the choroid, loses its pigmentary
character.
The middle layer consists of an exceedingly fine capillary plexus, formed by the
short ciliary vessels, and is known as the tunica Ruyschiana. 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 with those
of the ciliary processes.
The internal or pigmentary layer is a delicate membrane, consisting of a
single layer of hexagonal nucleated cells, loaded with pigment granules, and
applied to each other, so as to resemble a tessellated pavement. Each cell
contains a nucleus, and is filled with grains of pigment, which are in greater
abundance at the circumference of the cell. In perfect albinos this epithelium
contains no pigment, and none is present in the star-shaped cells found in the
other layers of the choroid.
The ciliary processes should be next examined ; they may be exposed, either by detaching the
iris from its connection with the ciliary ligament, or by making a transverse section of the globe,
and examining them from behind.
The Ciliary processes are formed by the plaiting or folding inwards of the
middle and internal layers of the choroid, at its anterior margin, and are received
CHOROID— IRIS.
619
between corresponding foldings of the suspensory ligament of the lens, thus
establishing a communication between the choroid and inner tunic of the eye.
They are arranged in a circle, behind the iris, round the margin of the lens.
They vary in number between sixty and eighty, 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 alter-
nation. The larger processes are each about one-tenth of an inch in length, and
Fig. 306. — The Arteries of the Choroid and Iris.
The Sclerotic has been mostly removed. (Enlarged.)
Jl nterior
Ciliary At
Short
Ciliary &i
nterior
CiliarijA^
hemispherical in shape, their periphery being attached to the ciliary ligament, and
continuous with the middle and inner layers of the choroid ; the opposite margin
is free, and rests upon the circumference of the lens. Their anterior surface is
turned towards the back of the iris, with the circumference of which it is con-
tinuous. The posterior surface is closely connected with the suspensory ligament
of the lens.
Structure. The ciliary processes are similar in structure to the choroid ; the
vessels are larger, having chiefly a longitudinal direction. Externally they are
covered with several layers of pigment cells; the component cells are small,
rounded, and full of pigment granules.
The Iris {iris, a rainbow) has received its name from the varied color it pre-
sents in different individuals. It is a thin circular-shaped, contractile curtain,
suspended in the aqueous humor behind the cornea, and in front of the lens,
being perforated at the nasal side of its centre by a circular aperture, the pupil,
for the transmission of light. By its circumference it is intimately connected
with the choroid; externally to this is the ciliary ligament, by which it is con-
nected to the sclerotic and cornea; its inner edge forms the margin of the pupil;
its surfaces are flattened, and look forwards and backwards, the anterior surface
towards the cornea, the posterior towards the ciliary processes and lens. The
anterior surface is variously colored in different individuals, and marked by lines
which converge towards the pupil. The posterior surface is of a deep purple
tint, from being covered by dark pigment; it is hence named uvea, from its
resemblance in color to a ripe grape.
Structure. The iris is composed of a fibrous stroma, muscular fibres, and pig-
ment cells.
The fibrous stroma consists of fine, delicate bundles of fibrous tissue, which have
a circular direction at the circumference; but the chief mass radiate towards
the pupil. They form, by their interlacement, a delicate mesh, in which the pig-
ment cells, vessels, and nerves are contained.
G20 ORGANS OF THE SENSES.
The muscular fibre is involuntary, and consists of circular and radiating fibres.
The circular fibres (sphincter of the pupil) 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 are separated somewhat, and form less complete circles.
The radiating fibres (dilator of the pupil) converge from the circumference towards
the centre, and blend with the circular fibres near the margin of the pupil. The
circular fibres contract the pupil, the radiating fibres dilate it.
The pigment cells are found in the stroma of the iris, and also as a distinct layer
on its anterior and posterior surfaces. In the stroma, the cells are ramified, and
contain yellow or brown pigment, according to the color of the eye. On the front
of the iris, there is a single layer of oval or rounded cells, with branching offsets.
On the back of the iris, there are several layers of small, round cells, filled with
dark pigment. *This layer is continuous with the pigmentary covering of the
ciliary processes.
The arteries of the iris are derived from the long and anterior ciliary, and from
the vessels of the ciliary processes.
Membrana pupillaris. In the foetus, the pupil is closed by a delicate, transparent
vascular membrane, the membrana pupillaris, which divides the space in which the
iris is suspended into two distinct chambers. This membrane contains numerous
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, converging
towards each other without anastomosing. Between the seventh and eighth month,
this membrane begins to disappear, by its gradual absorption from the centre
towards the circumference, and at birth only a few fragments remain. Sometimes
it remains permanent, and produces blindness.
The Ciliary ligament is a narrow ring of circular fibres, about one-fortieth of
an inch thick, and of a whitish color, which serves to connect the external and
middle tunics of the eye. It is placed round the circumference of the iris, at its
point of connection with the external layer of the choroid, the cornea, and sclerotic.
Its component fibres are delicate, and resemble those of elastic tissue. At its point
of connection with the sclerotic a minute canal is situated between the two, called
the sinus circular is iridis.
The Ciliary muscle (Bowman) consists of unstriped fibres ; it forms a grayish,
semi-transparent, circular band, about one-eighth of an inch broad, on the outer
surface of the forepart of the choroid. It is thickest in front, and gradually
becomes thinner behind. Its fibres are soft, of a yellowish- white color, longitu-
dinal in direction, and arise at the point of junction of the cornea and sclerotic.
Passing backwards, they are attached to the choroid, in front of the retina, and
correspond by their inner surface to the plicated part of the former membrane.
Mr. Bowman supposes that this muscle is so placed as to advance the lens, by
exercising compression on the vitreous body, and by drawing the ciliary processes
towards the line of junction of the sclerotic and cornea, and by this means to
adjust the eye to the vision of near objects.
The Retina.
The Retina may be exposed by carefully removing the choroid from its external
surface. It is a delicate nervous membrane, upon the surface of which the images
of external objects are received. Its outer surface is in contact with the pigmentary
layer of the choroid ; its inner surface, with the vitreous body. Behind, it is con-
tinuous with the optic nerve ; it gradually diminishes in thickness from behind
forwards ; and, in front, extends nearly as far forwards as the ciliary ligament,
where it terminates by a jagged margin, the ora serrata. It is soft, and semi-
transparent, in the fresh state ; but soon becomes clouded, opaque, and of a pinkish
tint. Exactly in the centre of the posterior part of the retina, and at a point
corresponding to the axis of the eye, in which the sense of vision is most perfect,
is a round, elevated, yellowish spot, called, after its discoverer, limbus luteus,
RETINA.
G21
yellow spot, of SG'mmering ; having a central depression at its summit, the fovea
centralis. The retina in the situation of the fovea centralis is exceedingly thin, so'
much so, that 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
Sommering" at first given to it. It exists only in man, the quadrumana, and some
saurian reptiles. Its use is unknown. About TV of an inch to the inner side of
the yellow spot is the point of entrance of the optic nerve ; the arteria centralis
retinse piercing its centre. This is the only part of the surface of the retina from
which the power of vision is absent.
Fig,
307. — The Arteria Centralis Retinse, Yellow Spot, etc., the Anterior Half
of the Eyeball being removed. (Enlarged.)
Sclerotic
Choroid
■Retina
Structure. The retina is composed of three layers, together with bloodvessels : —
External or columnar layer (Jacob's membrane).
Middle or granular layer.
Internal or nervous layer.
The bloodvessels do not form a distinct layer ; they ramify in the substance of
the internal layer.
The external or JacoVs membrane is exceedingly thin, and can be detached from
the external surface of the retina by the handle of the scalpel, in the form of a
flocculent film. It is thicker behind than in front, and consists of rod-like bodies
of two kinds : — 1. Columnar rods, solid, nearly of uniform size, and arranged per-
pendicularly to the surface. 2. Bulbous particles or cones, which are interspersed
at regular intervals among the former ; these are conical or flask-shaped, their
broad ends resting upon the granular layer, the narrow-pointed extremity being
turned towards the choroid ; they are not solid, like the columnar rods, but consist
of an external membrane with fluid contents. By their deep ends, both kinds are
joined to the fibres of Miiller.
The middle or granular layer forms about one-third of the entire thickness of
the retina. It consists of two laminae of rounded or oval nuclear particles, separated
from each other by an intermediate layer, which is transparent, finely fibrillated,
and contains no bloodvessels. The outermost layer is the thickest, and its con-
stituent particles are globular. The innermost layer is the thinnest ; its component
particles are flattened, looking like pieces of money seen edgeways ; hence it has
been called by Bowman, the nummular layer.
The internal or nervous layer is a thin semi-transparent membrane, consisting
of an expansion of the terminal fibres of the optic nerve and nerve cells. The
nerve fibres are collected into bundles, which radiate from the point at which the
trunk of the optic nerve terminates. As they proceed in a tolerably straight
G22 ORGANS OF THE SENSES.
course towards the anterior margin of the retina the bundles interlace, forming a
delicate net, with flattened elongated meshes. The nerve fibres which form this
layer differ from the fibres of the optic nerve in this respect ; they lose their dark
outline, and their tendency to become varicose, and consist only of the central
part or axis of the nerve tubes. The mode of termination of the nerve fibres is
unknown. According to some observers, they terminate in loops ; according to
others, in free extremities. Recent observers have stated, that some of the nerve
fibres are continuous with the caudate prolongations of the nerve cells external to
the fibrous layer. The nerve cells are placed on both sides of the fibrous layer,
but chiefly upon its inner surface, and imbedded within the meshes formed by the
interlacing nerve fibres ; they are round or pear-shaped transparent cells, nucleated,
with granular contents, furnished with caudate prolongations, some of which join
the fibres of the optic nerve, whilst others are directed externally towards the
granular layer. It is probable that these cells are identical with the ganglion cor-
puscles of vesicular nervous substance.
An extremely thin and delicate structureless membrane lines the inner surface
of the retina, and separates it from the vitreous body ; it is called the membrane
limitans.
The radiating fibres of the retina, described by Heinrich Miiller, consist of
extremely fine fibrillated threads, which are connected externally with each of the
rods of the columnar layer, of which they appear to be direct continuations ; and,
passing through the entire substance of the retina, are united to the outer surface
of the membrana limitans. In their course through the retina, they become con-
nected with the nuclear particles of the granular layer, and give off branching
processes opposite its innermost lamina ; as they approach the fibrous expansion
of the optic nerve, they are collected into bundles, which pass through the areolae*
between its fibres, and are finally attached to the inner surface of the membrana
limitans, where each fibre terminates in a triangular enlargement.
The arteria centralis retinse and its accompanying vein pierce the optic nerve,
and enter the globe of the eye through the porus opticus. It immediately divides
into four or five branches, which at first run between the hyaloid membrane and
the nervous layer ; but they soon enter the latter membrane, and form a close
capillary network in its substance. At the ora serrata they terminate in a single
vessel, which bounds the terminal margin of the retina.
The structure of the retina at the yellow spot presents some modifications.
Jacob's membrane is thinner, and of its constituents only the cones are present ;
but they are small, and more closely aggregated than in any other part. The
granular layer is absent over the fovea centralis. Of the two elements of the
nervous layer, the nerve fibres extend only to the circumference of the spot ; but
the nerve cells cover its entire surface. The radiating fibres are found at the cir-
cumference, and here only extend to the inner strata of the granular layer. Of
the capillary vessels, the larger branches pass round the spot, but the smaller capil-
laries meander through it. The color of the spot appears to imbue all the layers
except Jacob's membrane ; it is of a rich yellow, deepest towards the centre, and
does not appear to consist of pigment cells, but resembles more a straining of the
constituent parts.
humoes of the eye.
Aqueous Humoe.
The Aqueous Humor completely fills the anterior and posterior chambers of
the eyeball. It 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.
The anterior chamber is the space bounded in front by the cornea ; behind, by
the front of the iris and ciliary ligament.
The posterior chamber, smaller than the anterior, is bounded in front by the
VITREOUS BODY— CRYSTALLINE LENS. 623
iris; behind, by the capsule of the lens and its suspensory ligament, and the ciliary
processes.
In the adult, these two chambers communicate through the pupil ; but in the
foetus before the seventh month, when the pupil is closed by the membrana pupil-
laris, the two chambers are quite separate.
It has been generally supposed that the two chambers are lined by a distinct
membrane, the secreting membrane of the aqueous humor, analogous in struc-
ture to that of a serous sac. An epithelial covering can, however, only be found
on the posterior surface of the cornea. That the two chambers do, however,
secrete this fluid separately, is shown from its being found in both spaces before
the removal of the membrana pupillaris. It is probable that the parts concerned
in the secretion of the fluid are the posterior surface of the cornea, both surfaces
of the iris, and the ciliary processes.
Vitreous Body.
The Vitreous Body forms about four-fifths of the entire globe. It fills the
concavity of the retina, and is hollowed in front for the reception of the lens and
its capsule. It is perfectly transparent, of the consistence of thin jelly, and
consists of an albuminous fluid inclosed in a delicate, transparent membrane, the
hyaloid. This membrane invests the outer surface of the vitreous body ; it is
intimately connected in front with the suspensory ligament of the lens ; and is
continued into the back part of the capsule of the lens. It has been supposed by
Hannover, that from its inner surface numerous thin lamellae are prolonged
inwards 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 ; but in the foetus a peculiar fibrous texture pervades the mass, the
fibres joining at numerous points, and presenting minute nuclear granules at their
point of junction. The fluid from the vitreous body resembles nearly pure water;
it contains, however, some salts, and a little albumen.
In the foetus, the centre of the vitreous humor presents a tubular canal, through
which a minute artery passes along the vitreous body to the capsule of the lens. In
the adult, no vessels penetrate its substance; so that its nutrition must be carried
on by the vessels of the retina and ciliary processes, situated upon its exterior.
Crystalline Lens and its Capsule.
The Crystalline Lens, inclosed in its capsule, is situated immediately behind
the pupil, in front of the vitreous body, and surrounded by the ciliary processes,
which slightly overlap its margin.
The capsule of the lens is a transparent, highly elastic, and brittle membrane,
which closely surrounds the lens. It rests, behind, in a depression in front of
the vitreous body : in front, it forms part of the posterior chamber of the eye ; and
it is retained in its position chiefly by the suspensory ligament of the lens. The
capsule is much thicker in front than behind, structureless in texture ; and when
ruptured, the edges roll up with the outer surface innermost, like the elastic laminae
of the cornea. The lens is connected to the inner surface of the capsule by a single
layer of transparent, polygonal, nucleated cells. These, after death, absorb moisture
from the fluids of the eye ; and, breaking down, form the liquor Morgagni.
In the foetus, a small branch from the arteria centralis retinae runs forwards, as
already mentioned, through the vitreous humor to the posterior part of the cap-
sule of the lens, where its branches radiate and form a plexiform network, which
covers its surface, and are continuous round 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.
The lens is a transparent, double convex body, the convexity being greater on
the posterior than on the anterior surface. It measures about a third of an inch
in the transverse diameter, and about one-fourth in the antero-posterior. It
624 ORGANS OP THE SENSES.
consists of concentric layers, of which the external, in the fresh state, are soft and
easily detached ; those beneath are firmer, the central ones forming a hardened
nucleus. These laminae are best demonstrated by
Fig. 308.— The Crystalline Lens, boiling, or immersion in alcohol. The same reagents
hardened ai^d divided. demonstrate that the lens consists of three triangular
n arge .) segments, the sharp edges of which are directed towards
the centre, the bases towards the circumference. The
laminae consist of minute parallel fibres, which are
united to each other by means of wavy margins, the
convexities upon one fibre fitting accurately into the
concavities of the adjoining fibre.
The changes produced in the lens by age are the fol-
lowing : —
In the foetus, its form is nearly spherical, its color of
a slightly reddish tint, not perfectly transparent, and so
soft as to readily break down 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.
The suspensory ligament of the lens is a thin, transparent, membranous struc-
ture, placed between the vitreous body and the ciliary processes of the choroid :
it connects the anterior margin of the retina with the anterior surface of the lens,
near its circumference. It assists in retaining the lens in its position. Its outer
surface presents a number of folds or plaitings, in which the corresponding folds
of the ciliary processes are received. These plaitings are arranged round the
lens in a radiating form, and are stained by the pigment of the ciliary processes.
The suspensory ligament consists of two layers, which commence behind, at the
ora serrata. The external, a tough, milky, granular membrane, covers the inner
surface of the ciliary processes, and extends as far forwards as their anterior
free extremities. The inner layer, an elastic transparent, fibro-membranous
structure, extends as far forwards as the anterior surface of the capsule of the
lens, near its circumference. That portion of this membrane which intervenes
between the ciliary processes and the capsule of the lens, forms part of the boun-
dary of the posterior chamber of the eye. The posterior surface of this layer is
turned towards the hyaloid membrane, being separated from it at the circum-
ference of the lens by a space called the canal of Petit.
The canal of Petit is about one-tenth of an inch wide. It is bounded in front
by the suspensory ligament ; behind, by the hyaloid membrane, its base being
formed by the capsule of the lens. When inflated with air, it is sacculated at
intervals, owing to the foldings on its anterior surface.
Bloodvessels and Nerves of the Eye.
The Vessels of the globe of the eye are the short, long, and anterior ciliary
arteries, and the arteria centralis retinas.
The short ciliary arteries pierce the back part of the sclerotic, round the entrance
of the optic nerve, and divide into branches which run parallel with the axis of
the eyeball : they are distributed to the middle layer of the choroid, and ciliary
processes.
The long ciliary arteries, two in number, pierce the back part of the sclerotic,
and run forward, between this membrane and the choroid, to the Ciliary muscle,
where they each divide into an upper and lower branch; these anastomose,
and form a vascular circle round the outer circumference of the iris ; from this
circle branches are given off which unite, near the margin of the pupil, in a
smaller vascular circle. These branches, in their course, supj)ly the muscular
structure.
APPENDAGES OF THE EYE. . 625
The anterior ciliary arteries, five or six in number, are branches of the muscular
and lachrymal branches of the ophthalmic. They pierce the eyeball, at the
anterior part of the sclerotic, immediately behind the margin of the cornea, and
are distributed to the ciliary processes, some branches joining the greater vascular
circle of the iris.
The arteria centralis retinse has been already described.
The veins, usually four in number, are formed mainly by branches from the
surface of the choroid. They perforate the sclerotic, midway between the cornea
and the optic nerve, and end in the ophthalmic vein.
The nerves of the eyeball are the optic, the long ciliary nerves from the nasal
branch of the ophthalmic, and the short ciliary nerves from the ciliary ganglion.
Appendages of the Eye.
The appendages of the eye {tutamina oculi) include the eyebrows, the eyelids,
the conjunctiva, and the lachrymal apparatus, viz., the lachrymal gland, the
lachrymal sac, and the nasal duct.
The eyebrows {supercilia) 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. In structure, they 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 eyelids (palpebrse) are two thin, movable folds, placed in front of the eye,
protecting it from injury by their closure. The upper lid is the larger, the more
movable of the two, and supplied by a separate elevator muscle, the Levator
palpebrse superioris. When the eyelids are opened, an elliptical space {fissura
palpebrarun%) is left between their margins, the angles of which correspond to the
junction of the upper and lower lids, and are called canthi.
The outer canthus is more acute than the inner, and the lids here lie in close
contact with the globe ; but the inner canthus is prolonged for a short distance
inwards, towards the nose, and the two lids are separated by a triangular space,
the lacus lacrymalis. At the commencement of the lacus lacrymalis, on the
margin of each eyelid, is a small conical elevation, the lachrymal papilla, or
tubercle, the apex of which is pierced by a small orifice, the vunctum lacrymale,
the commencement of the lachrymal canal.
Structure of the eyelids. The eyelids are composed of the following structures,
taken in their order from without inwards : —
Integument, areolar tissue, fibres of the Orbicularis muscle, tarsal cartilage,
fibrous membrane, 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, are thin,
pale in color, and possess an involuntary action.
The tarsal cartilages are two thin elongated plates of fibro-cartilage, about an
inch in length. They are placed one in each lid, contributing to their form and
support.
The superior, 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.
Into the fore part of this cartilage the aponeurosis of the Levator palpebrse is
attached.
The inferior tarsal cartilage, the smaller, is thinner, and of an elliptical
form.
40
626
ORGANS OF THE SENSES.
The free or ciliary margin of the cartilages is thick, and presents a j^erfectlj
straight edge. The attached or orbital margin is connected to the circumference
of the orbit by the fibrous membrane of the lids. The outer angle of each
cartilage is attached to the malar bone by the external palpebral or tarsal ligament.
The inner angles of the two cartilages terminate at the commencement of the lacus
lacrymalis, being fixed to the margins of the orbit by the tendo oculi.
The fibrous membrane of the lids, or tarsal ligament is a layer of fibrous
membrane, beneath the Orbicularis, attached, externally, to the margin of the
orbit, and internally to the orbital margin of the lids. It is thick and dense at
the outer part of the orbit, but becomes thinner as it approaches the cartilages.
This membrane serves to support the eyelids, and retains the tarsal cartilages in
their position.
The Meibomian glands (fig. 309) are situated upon the inner surface of the
eyelids, between the tarsal cartilages 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 cartikge,
FiL
309. — The Meibomian Glands, etc., seen from the Inner Surface
of the Eyelids.
JboNb
Xar/iri/iiial.
and somewhat fewer in the lower. They are imbedded in grooves in the inner
surface of the cartilages, and correspond in length with the breadth of each
cartilage ; 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 number to the follicles. These glands are a variety of the
cutaneous sebaceous glands, each consisting of a single straight tube or follicle,
having a ccecal termination, into which open a number of small secondary follicles.
The tubes consist of basement membrane, covered by a layer of scaly epithelium ;
the cells are charged with sebaceous matter, which constitutes the secretion. The
peculiar parallel arrangement of these glands side by side forms a smooth layer,
admirably adapted to .the surface of the globe, over which they constantly glide.
The use of their secretion is to prevent adhesion of the lids.
The eyelashes (cilia) 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
upwards; those of the lower lid curve downwards, by which means they do not
interlace in closing the lids.
The conjunctiva is the mucous membrane of the eye. It lines the inner surface
LACHRYMAL APPARATUS. 627
of the eyelids, and is reflected over the fore part of the sclerotic and cornea. In
each of these situations, its structure presents some peculiarities.
The palpebral portion of the conjunctiva is thick, opaque, highly vascular, and
covered with numerous papilke, which, in the disease called granular lids, become
greatly hypertrophied. 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, it may be traced along the lachrymal ducts into
the lachrymal gland ; and at the inner angle of the eye, it forms a semilunar
fold, the plica semilunaris. 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. Upon the sclerotic, the conjunctiva is
loosely connected to the globe; it becomes thinner, loses its papillary structure,
is transparent, and only slightly vascular in health. Upon the cornea, the con-
junctiva is extremely thin and closely adherent, and no vessels can be traced into
it in the adult in a healthy state. In the foetus, fine capillary loops extend, for
some little distance forwards, into this membrane ; but in the adult they pass only
to the circumference of the cornea.
The caruncula lacrymalis is a small, reddish, conical-shaped body, situated
at the inner canthus of the eye, and filling up the small triangular space in this
situation, the lacus lacrymalis. It consists of a cluster of follicles similar in
structure to the Meibomian, covered with mucous membrane, 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 mucous membrane, the concavity of which is directed
towards the cornea; it is called the plica semilunaris. Between its two layers is
found a thin plate of cartilage. This structure is considered to be the rudiment
of the third eyelid in birds, the membrana nictitans.
Lachrymal Apparatus (fig. 310).
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,
Fig. 310. — The Lachrymal Apparatus. Right Side.
This fluid is carried away by the lachrymal canals into the lachrymal sac, ana
along the nasal duct into the cavity of the nose.
G28 ORGANS OF THE SENSES.
The lachrymal gland is lodged in a depression at the outer angle of the orbit,
on the inner side of the external 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, aud
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, and is covered, on its inner surface, by a reflection of the
conjunctiva. This margin is separated from the rest of the gland by a slight
depression, hence it is sometimes described as a separate lobe, called the palpe-
bral portion of the gland. In structure and general appearance, it resembles the
salivary glands. Its ducts, about seven 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.
The lachrymal canals commence at the minute orifices, puncta lacrymalia,
seen on the margin of the lids, at the outer extremity of the lacus lacrymalis.
They commence on the summit of a slightly elevated papilla, the papilla lacry-
malis, and lead into minute canals, the canaliculi, which proceed inwards to
terminate in the lachrymal sac. The superior canal, the smaller and longer of
the two, at first ascends, and then bends at an acute angle, and passes inwards and
downwards to the lachrymal sac. The inferior canal at first descends, and then,
abruptly changing its course, passes almost horizontally inwards. They are dense
and elastic in structure, and somewhat dilated at their angle.
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 nasal process of the
superior maxillary. It is oval in form, its upper extremity being closed in and
rounded, whilst below it is continued into the nasal duct. It is covered by the
Tensor tarsi muscle and by a fibrous expansion derived from the tendo oculi,
which is attached to the ridge on the lachrymal bone. In structure, it consists of
a fibrous elastic coat, lined internally by mucous membrane ; the latter is continuous,
through the canaliculi, with the mucous lining of the conjunctiva, and through the
nasal duct with the pituitary membrane of the nose.
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 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 extremity, and takes a
direction downwards, backwards, and a little outwards. It is lined by mucous
membrane, which is continuous below with the pituitary lining of the nose. In
the canaliculi, this membrane is provided with scaly epithelium; but in the
lachrymal sac and nasal duct, the epithelium is ciliated as in the nose.
The Ear.
The Organ of Hearing consists of three parts ; the external ear, the middle ear
or tympanum, and the internal ear or labyrinth.
External Ear.
The External Ear consists of an expanded portion named the pinna or auricle,
and the auditory canal or meatus. The former serves to collect the vibrations of
the air constituting sound, and the latter conducts those vibrations to the tym-
panum.
The pinna or auricle (fig. 311) consists of a layer of cartilage, covered by
integument, and connected to the commencement of the auditory canal ; it is of an
TIIE EAR.
G29
Fig. 311. — The Pinna or Auricle.
Outer Surface.
ovoid form, its surface uneven, with its larger end directed upwards. Its outer
surface is irregularly concave, directed slightly forwards, and 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 pro-
minent rim of the auricle is called the helix.
Another curved prominence, parallel with,
and in front of, the helix, is called the anti-
helix ; this bifurcates above into two parts,
so as to inclose a triangular depression, the
fossa of the antihelix. The narrow curved
depression between the helix and antihelix
is called the /055a of the helix {fossa innomi-
rtata seu scaphoidea). The antihelix de-
scribes a circuit round a deep, capacious
cavity, the concha, which is partially divided
into two parts by the commencement of the
helix. In front of the concha, and project-
ing backwards over the meatus, is a small
pointed eminence, the tragus; so called
from its being generally covered, on its under
surface, with a tuft of hair, resembling a
goat's beard. Opposite the tragus, and sepa-
rated from it by a deep notch (incisura
intertragica), is a small tubercle, the anti-
tragus. Below this is the lobule, composed
of tough areolar and adipose tissues, wanting
the firmness and elasticity of the rest of the
pinna.
Structure of the pinna. The pinna is composed of a thin plate of yellow
cartilage, covered with integument, and connected to the surrounding parts by
ligaments, and a few muscular fibres.
The integument is thin, closely adherent to the cartilage, and furnished with
sebaceous glands, which are most numerous in the concha and scaphoid fossa.
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 construction of all parts of the auricle,
and presents several intervals or fissures in its substance, which partially separate
the different parts. Thus, it does not form a constituent part of the lobule ; it is
deficient, also, between the tragus and beginning of the helix, the notch between
them being filled up by dense fibrous tissue. The fissures in the cartilage are the
fissure of the helix, a short, vertical slit, situated at the fore part of the pinna,
immediately behind a small conical projection of cartilage, opposite the first curve
of the helix {process of the helix) ; another fissure, the fissure of the tragus, is
seen upon the anterior surface of the tragus. The antihelix is divided below, by
a deep fissure, into two parts ; one part terminates by a pointed, tail-like extremity
{processus caudatus) ; the other is continuous with the antitragus. The cartilage
of the pinna is very pliable, elastic, of a yellowish color, and similar in structure to
the cartilages of the ala3 nasi.
The ligaments of the pinna consist of two sets: — 1. Those connecting it to
the side of the head. 2. Those connecting the various parts of its cartilage
together.
The former, the most important, are two in number, anterior and posterior.
The anterior ligament extends from the process of the helix to the root of the
zygoma. The posterior ligament passes from the posterior surface of the concha
to the outer surface of the mastoid process of the temporal bone. A few fibres
connect the tragus to the root of the zygoma.
Those connecting the various parts of the cartilage together are also two in
630 ORGANS OF THE SENSES.
number. Of these, one is 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 ; the other extends between the concha and
the processus caudatus.
The muscles of the pinna (fig. 312), like the ligaments, also consist of two sets : —
1. Those which connect it with the side of the head, moving the pinna as a whole,
Fig. 312.— The Muscles of the Pinna.
viz., the Attollens aurem, Attrahens aurem, and Retrahens aurem (p. 241). 2.
The proper muscles of the pinna, which extend from one part of the auricle to
another. These are the
Helicis major. Antitragicus.
Helicis minor. Transversus auriculae.
Tragicus. Obliquus auris.
The Helicis major is a narrow, vertical band of muscular fibres, situated upon
the anterior margin of the helix. It arises, below, from the tubercle of the helix,
and is inserted into the anterior border of the helix, just where it is about to
curve backwards. It is pretty constant in its existence.
The Helicis minor is an oblique fasciculus, firmly attached to that part of the
helix which commences from the bottom of the concha.
The 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 arises from the outer part of the antitragus ; its fibres are
inserted into the processus caudatus oftheanti helix. This muscle is usually very
distinct.
The Transversus auriculae is placed on the cranial surface of the pinna. It
consists of radiating fibres, partly tendinous and partly muscular, extending from
the convexity of the concha to the prominence corresponding with the groove of
the helix.
AUDITORY CANAL.
631
The Obliquus auris (Todd) 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 are the posterior auricular, from the external carotid ;
the anterior auricular, from the temporal ; and. an auricular branch from the occi-
pital artery.
The veins accompany the corresponding arteries.
The nerves are the auricularis magnus, from the cervical plexus ; the posterior
auricular, from the facial ; the auricular branch of the pneumogastric ; and the
auriculo-temporal branch of the inferior maxillary nerve.
The Auditory Canal, meatus auditorius externus (fig. 313), extends from the
bottom of the concha to the membrana tympani. It is about an inch and. a
quarter in length, its direction obliquely forwards and inwards, and it is slightly
Fig. 313. — A Front View of the Organ of Hearing. Right Side.
Incus
\ Ma. 1 leas
\\ S tap i3
^^^tSimi-ehvalar Ca^ia.1'
\'t»ft>:,*
if .Cochlt^
curved upon itself, so as to be higher in the middle than at either extremity. It
forms an oval cylindrical canal, narrowest at the middle, somewhat flattened from
before backwards, the greatest diameter being in the vertical direction at the ex-
ternal orifice ; but, in the transverse direction, at the tympanic end. The membrana
tympani, which occupies the termination of the meatus, is obliquely directed, in
consequence of the floor of this canal being longer than the roof, and the anterior
wall longer than the posterior. The auditory canal is formed partly by cartilage
and membrane, and partly by bone.
The cartilaginous portion is about half an inch in length, being rather less than
half the canal ; it is formed by the cartilage of the concha and tragus, being pro-
longed inwards to the circumference of the auditory process, to which it is firmly
attached. This tube 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 (incisure Santorini), which extend through the cartilage
in a vertical direction.
The osseous portion is about three-quarters of an inch in length, and narrower
than the cartilaginous portion. It is directed inwards and a little forwards, forming
a slight curve in its course, the convexity of which is upwards and backwards.
Its inner end, which communicates with the cavity of the tympanum, is smaller
than the outer, and sloped, the anterior wall projecting beyond the posterior about
two lines ; it is marked, excepting at its upper part, by a narrow groove for the
insertion of the membrana tympani. Its outer end 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
C32 ORGANS OF THE SENSES.
downwards. 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 (tympanic bone),
incomplete at its upper part.
The skin lining the meatus is very thin, closely adherent to the cartilaginous
and osseous portions of the tube, and covers the surface of the membrana tympani,
forming its outer layer. After maceration, the thin pouch of epidermis, when
withdrawn, preserves the form of the meatus. The skin near the orifice is fur-
nished with hairs and sebaceous glands. In the thick subcutaneous tissue of the
cartilaginous part of the meatus are numerous ceruminous glands, which secrete
the ear wax, the ducts of which open on the surface of the skin.
The arteries supplying the meatus are branches from the posterior auricular,
internal maxillary, and temporal.
The nerves are chiefly derived from the temporo-auricular branch of the inferior
maxillary nerve.
i Middle Ear or Tympanum.
The middle ear or tympanum is an irregular cavity, compressed from without
inwards, and situated within the petrous bone. It is placed above the jugular
fossa, the carotid canal lying in front, the mastoid cells behind, the meatus audito-
rius externally, and the labyrinth within. It is filled with air, and communicates
with the pharynx by the Eustachian tube. The tympanum is traversed by a
chain of movable bones, which connect the membrana tympani with the laby-
rinth, and serve to convey the vibrations communicated to the membrana tympani
across the cavity of the tympanum to the internal ear.
The cavity of the tympanum measures about five lines from before backwards,
three lines in the vertical direction, and between two and three in the transverse,
being a little broader behind and above than below and in front. It is bounded
externally by the membrana tympani and meatus ; internally, by the outer surface
of the internal ear; behind, by the mastoid cells; and, in front, by the Eustachian
tube and canal for the Tensor tympani. Its roof and floor are formed by thin
osseous laminae, which connect the squamous and petrous portions of the temporal
bone.
The roof is broad, flattened, and formed of a thin plate of bone, which separates
the cranial and tympanic cavities.
The floor is narrow, and corresponds to the jugular fossa, which lies beneath.
The outer wall is formed by the membrana tympani, a small portion of bone
being seen above and below this membrane. It presents three small apertures,
the iter chordae posterius, the Glaserian fissure, and the iter chordae anterius.
The aperture of the iter chordee posterius is behind the aperture for the membrana
tympani, close to its margin, at a level with its centre ; it leads into a minute canal,
which descends in front of the aquaeductus Fallopii, and terminates in this canal
near the stylo-mastoid foramen. Through it the chorda tympani nerve enters the
tympanum.
The Glaserian fissure opens just above and in front of the orifice of the mem-
brana tympani; in this situation it is a mere slit, about a line in length. It gives
passage to the long process of the malleus, the Laxator tympani muscle, and some
tympanic vessels.
The aperture of the iter chordae anterius is seen just above the preceding fissure ;
it leads into a canal (canal of Huguier), which runs parallel with the Glaserian
fissure. Through it the chorda tympani nerve leaves the tympanum.
The internal wall of the tympanum is vertical in direction, and looks directly
outwards. It presents for examination the following parts : —
Fenestra ovalis. Eidge of the Aquaeductus Fallopii.
Fenestra rotunda. Pyramid.
Promontory. . Opening for the Stapedius.
THE TYMPANUM.
633
The fenestra ovalis is a reniform opening, leading from the tympanum into
the vestibule ; its long diameter is directed horizontally, and its convex border
upwards. The opening in the recent state is closed by the lining membrane
common to both cavities, and is occupied by the base of the stapes. This mem-
brane is placed opposite the membrana tympani, and is connected with it by the
ossicula auditus.
The fenestra rotunda is an oval aperture, placed at the bottom of a funnel-
shaped depression, leading into the cochlea. It is placed below and rather behind
Fig. 314. — View of Inner Wall of Tympanum. (Enlarged.)
Chorda Tjjn^a
the fenestra ovalis, from which it is separated by a rounded elevation, the pro-
montory ; it is closed in the recent state by a membrane {membrana tympani
secundaria, Scarpa). This membrane is concave towards the tympanum, convex
towards the cochlea. It consists of three layers; the external or mucous,
derived from the mucous lining of the tympanum ; the internal or serous, from
the lining membrane of the cochlea ; and an intermediate or fibrous layer.
The promontory is a rounded hollow prominence, formed by the projection
outwards of the first turn of the cochlea ; it is placed between the fenestras, and
furrowed on its surface by three small grooves, which lodge branches of the
tympanic plexus.
The rounded eminence of the aquseductm Fallopii is placed between the fenestra
ovalis and roof of the tympanum ; it is the prominence of the bony canal in which
the portio dura is contained. It traverses the inner wall of the tympanum above
the fenestra ovalis, and, behind that opening, curves nearly vertically downwards
along the posterior wall.
The pyramid 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
forwards towards the vestibular fenestra, 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 aquaeductus Fallopii.
The posterior wall of the tympanum is wider above than below, and presents
for examination the
Openings of the Mastoid Cells.
These consist of one large irregular aperture, and several smaller openings,
situated at the upper part of the posterior wall ; they lead into canals, which com-
municate with large irregular cavities contained in 'the interior of the mastoid
634 ORGANS OF THE SENSES.
process. These cavities vary considerably in number, size, and form ; they are
lined by mucous membrane, continuous with that covering the cavity of the
tympanum.
The anterior wall of the tympanum is wider above than below ; it corresponds
with the carotid canal, from which it is separated by a thin plate of bone ; it
presents for examination the
Canal for the Tensor tympani. Orifice of the Eustachian Tube.
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 interior wall, being separated from
each other by a thin, delicate horizontal plate of bone, the processus cochleari-
formis. 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 is the superior and the smaller of the two : it
is rounded and lies beneath the upper surface of the petrous bone, close to the
hiatus Fallopii. The tympanic end of this canal forms a conical eminence, which
is prolonged backwards into the cavity of the tympanum, and is perforated at its
summit by an aperture, which transmits the tendon of the muscle contained in it.
This eminence is sometimes called the anterior pyramid. The canal contains the
Tensor tympani muscle.
The Eustachian tube is the channel through which the tympanum communicates
with the pharynx. Its length is from an inch and a half to two inches, and its
direction downwards, forwards, and inwards. It is formed partly of bone, partly
of cartilage and fibrous tissue.
The osseous portion is about half an inch in length. It commences in the lower
part of the anterior wall of the tympanum, below the processus cochleariformis,
and, gradually narrowing, terminates in an oval dilated opening, at the angle of
junction of the petrous and squamous portions, its extremity presenting a jagged
margin, which serves for the attachment of the cartilaginous portion.
The cartilaginous portion, about an inch in length, is formed of a triangular
plate of cartilage, curled upon itself, an interval being left below, between the
non-approximated margins of the cartilage, which is completed by fibrous tissue.
Its canal is narrow behind, wide, expanded, and somewhat trumpet-shaped in
front, terminating by an oval orifice, placed at the upper part and side of the
pharynx, behind the back part of the inferior meatus. Through this canal
the mucous membrane of the pharynx is continuous with, that which lines the
tympanum.
The membrana tympani separates the cavity of the tympanum from 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 down-
wards and inwards. Its circumference is contained in a groove at the inner end
of the meatus, which skirts the circumference of this part excepting above. The
handle of the malleus descends vertically between the inner and middle layers
of this membrane as far down as its centre, where it is firmly attached, drawing
the membrane inwards, so that its outer surface is concave, its inner convex.
Structure. This membrane is composed of three layers, an external or cuticular,
a middle or fibrous, and an internal or mucous. The cuticular lining is derived
from the integument lining the meatus. The fibrous layer consists of fibrous and
elastic tissues ; some of the fibres radiate from near the centre to the circumfer-
ence ; others are arranged, in the form of a dense circular ring, round the attached
margin of the membrane. The mucous lining is derived from the mucous lining
of the tympanum. The vessels pass to the membrana tympani along the handle
of the malleus, and are distributed between its layers.
Ossicles of the Tympanum. The tympanum is traversed by a chain of
movable bones, three in number, the malleus, incus, and stapes. The former is
OSSICLES OF THE TYMPANUM. 635
attached to the membrana tympani, the latter to the fenestra ovalis, the incus
being placed between the two, to both of which it is connected by delicate
articulations.
The Malleus, so named from its fancied resemblance to a hammer, consists of a
head, neck, handle or manubrium, and two processes, viz., the processus gracilis
and the processus brevis.
The head is the large upper extremity of the bone ; it is oval in shape, and
articulates posteriorly with the incus, being free in the rest of its extent.
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 manubrium is a vertical portion of bone, which is connected by its outer
margin with the membrana tympani. It decreases in size towards its extremity,
where it is curved slightly forwards, and flattened from within outwards.
The processus gracilis is a long and very delicate process, which passes from
the eminence below the neck forwards and outwards to the Glaserian fissure, to
which it is connected by bone and ligamentous fibres. It gives attachment to the
Laxator tympani.
The processus brevis is a slight conical projection, which springs from the root
of the manubrium, and lies in contact with the membrana tympani. Its summit
gives attachment to the Tensor tympani.
The Incus has received its name from its resemblance to an anvil, but it does
not look unlike a bicuspid tooth, with two
roots, which differ in length, and are widely
separated from each other. It consists of a Fi«- ™^Z Sld^l"?ed T' "~
body and two processes.
The body is somewhat quadrilateral, but
compressed laterally. Its summit is deeply
concave, and articulates with the malleus ; in
the fresh state, it is covered with cartilage
and lined with synovial membrane.
The two processes diverge from one
another nearly at right angles.
The sltort process, somewhat conical in
shape, projects nearly horizontally back-
wards, and is attached to the margin of the
opening leading into the mastoid cells by
ligamentous fibres.
The long process, longer and more slender than the preceding, descends nearly
vertically behind the handle of the malleus, and, bending inwards, terminates in a
rounded globular projection, the os orbiculare, tipped with cartilage, and articu-
lating with the head of the stapes. In the foetus the os orbiculare exists as a
separate bone, but becomes united to the long process of the incus in the adult.
The Stapes, so called from its close resemblance to a stirrup, consists of a head,
neck, two branches, and a base.
The head presents a depression, tipped with cartilage, which articulates with
the os orbiculare.
The neck, the constricted part of the bone below the head, receives the insertion
of the Stapedius muscle.
The two branches or crura diverge from the neck, and are connected at their
extremities by a flattened, oval-shaped plate (the base), which forms the foot of
the stirrup, and is fixed to the margin of the fenestra ovalis by ligamentous fibres.
Ligaments of the Ossicula. These small bones are connected with each other,
and with the tympanum, by ligaments, and moved by small muscles. The articular
surfaces of the malleus and incus, the orbicular process of the incus and the head
of the stapes, are covered with cartilage, connected together by delicate capsular
ligaments, and lined by synovial membrane. The ligaments connecting the ossicula
with the walls of the tympanum are three in number, one for each bone.
«36 ORGANS OF THE SENSES.
The suspensory ligament of the malleus is a delicate, round bundle of fibres,
which, descends perpendicularly from the roof of the tympanum to the head of the
malleus.
The posterior ligament of the incus is a short, thick, ligamentous band, which
connects the extremity of the short process of the incus to the posterior wall of
the tympanum, near the margin of the opening of the mastoid cells.
The annular ligament of the stapes connects the circumference of the base of
this bone to the margin of the fenestra ovalis.
A suspensory ligament of the incus has been described by Arnold, descending
from the roof of the tympanum to the upper part of the incus, near its articulation
with the malleus.
The Muscles of the tympanum are three : —
Tensor tympani. Laxator tympani. Stapedius.
The Tensor tympani, the largest, is contained in a 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 backwards, it terminates in a slender tendon, which is
reflected outwards over the processus cochleariformis, and is inserted into the
handle of the malleus, near its root. It is supplied by a branch from the otic
ganglion.
The Laxator tympani major (Sommering) arises from the spinous process of
the sphenoid bone, and from the cartilaginous portion of the Eustachian tube;
passing backwards through the Glaserian fissure, it is inserted into the neck of
the malleus, just above the processus gracilis. It is supplied by the tympanic
branch of the facial.
The Laxator tympani minor (Sommering) arises from the upper and back part
of the external meatus, passing forwards and inwards between the middle and
inner layers of the membrana tympani; it is inserted into the handle of the
malleus, and processus brevis. This is considered as a ligament by some
anatomists.
The Stapedius arises from the sides of a conical cavity hollowed out of the
interior of the pyramid ; its tendon emerges from the orifice at its apex, and,
passing forwards, 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 a filament from the facial
nerve.
Actions. The Tensor tympani draws the membrana tj^mpani inwards, and thus
heightens its tension. The Laxator tympani draws the malleus outwards, and
thus the tympanic membrane, especially at its fore part, is relaxed. The Stapedius
depresses the back part of the base of the stapes, and raises its fore part. It
probably compresses the contents of the vestibule.
The Mucous Membrane of the tympanum is thin, vascular, and continuous with
the mucous membrane of the pharynx, through the Eustachian tube. It invests
the ossicula, and the muscles and nerves contained in the tympanic cavity, forms
the internal layer of the membrana tympani, covers the foramen rotundum, and
is reflected into the mastoid cells, which it lines throughout. In the tympanum
and mastoid cells, this membrane is pale, thin, slightly vascular, and covered with
ciliated epithelium. 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 laminar ciliated epithelium, and provided with numerous mucous
glands.
The Arteries supplying the tympanum are five in number, viz., the tympanic
branch of the internal maxillary, which supplies the membran/i tympani ; the
stylo-mastoid branch of the posterior auricular, which supplies the back part of
the tympanum and mastoid cells ; the smaller branches being the petrosal branch
INTERNAL EAR. 637
of the middle meningeal, and branches from the ascending pharyngeal and internal
carotid.
The Veins of the tympanum terminate in the middle meningeal and pharyngeal
veins, and, through these, in the internal jugular.
The Nerves of the tympanum may be divided into : — 1. Those supplying the mus-
cles. 2. Those distributed to the lining membrane. 3. Branches communicating
with other nerves.
Nerves to muscles. The Tensor tympani is supplied by a branch from the otic
ganglion ; the Laxator tympani and the Stapedius, by a filament from the facial
(Sommering).
The nerves distributed to the lining membrane are derived from the tympanic
plexus.
Communications between the following nerves take place in the tympanum ; the
tympanic branch, from the petrous ganglion of the glossopharyngeal ; a filament
from the carotid plexus ; a branch which joins the great superficial petrosal nerve
from the Vidian ; and a branch to the otic ganglion (small superficial petrosal
nerve).
The tympanic branch of the glossopharyngeal (Jacobson's nerve) enters the tym-
panum by an aperture in its floor, close to the inner wall, and ascends on to the
promontory. It distributes filaments to the lining membrane of the tympanum,
and divides into three branches, which are contained in grooves on the promontory,
and serve to connect this with other nerves. One branch runs in a groove, for-
wards and downwards, to an aperture situated at the junction of the anterior and
inner walls, just above the floor, and enters the carotid canal, to communicate
with the carotid plexus of the sympathetic. The second branch is contained in
a groove which runs vertically upwards to an aperture on the inner wall of the
tympanum, just beneath the anterior pyramid, and in front of the fenestra ovalis.
The canal leading from this opens into the hiatus Fallopii, where the nerve
contained in it joins the great petrosal nerve. The third branch ascends towards
the anterior surface of the petrous bone ; it then passes through a small aperture
in the sphenoid and temporal bones to the exterior of the skull, and joins the otic
ganglion. As this nerve passes by the gangliform enlargement of the facial, it
has a connecting filament with it.
The chorda tympani quits the facial near the stylo-mastoid foramen, enters
the tympanum at the base of the pyramid, and arches forwards across its cavity,
between the handle of the malleus and long process of the incus, to an opening
internal to the Glaserian fissure. It is invested by a reflection of the lining mem-
brane of the tympanum.
Internal Ear or Labyrinth.
The internal ear is the essential part of the acoustic organ, receiving the ulti-
mate distribution of the auditory nerve. It is called the labyrinth, from the com-
plexity of its communications, and consists of three parts, the vestibule, semi-
circular canals, and cochlea. It consists of a series of cavities, channelled out of
the substance of the petrous bone, communicating externally with the cavity of
the tympanum, through the fenestra ovalis and fenestra rotunda ; and internally,
with the meatus auditorius internus, which contains the auditory nerve. Within the
osseous labyrinth is contained the membranous labyrinth, upon which the ramifi-
cations of the auditory nerve are distributed.
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 semicircular canals. It is somewhat ovoidal in shape
from before backwards, flattened from side to side, and measures about one-fifth of
an inch from before backwards, as well as from above downwards, being narrower
from without inwards. On its outer or tympanic wall is the fenestra ovalis,
closed, in the recent state, by the base of the stapes, and its annular ligament.
C38 ORGANS OF THE SENSES.
On its inner wall, at its fore part, is a small circular depression, fovea hemisplie-
rica; it is perforated, at its anterior and inferior part (macula cribrosa), by seve-
ral minute holes for the passage of filaments of the auditory nerve ; and behind
it is a vertical ridge, the pyramidal eminence. At the hinder part of the inner
wall is the orifice of the aquseductus vestibuli, which extends to the posterior sur-
face of the petrous portion of the temporal bone. It transmits a small vein, and,
Fig. 316. — The Osseous Labyrinth laid open. (Enlarged.)
Opcrrim,
Jlm*f/e passed t/troit,
I'am m . rotund.
Opening of
according to some, contains a tubular prolongation of the lining membrane of the
vestibule, which ends in a cul-de-sac, between the layers of the dura mater within
the cranial cavity. On the upper wall or roof is a transversely-oval depression,
fovea semi-elliptica, separated from the fovea hemispherica by the pyramidal
eminence, already mentioned. Behind, the semicircular canals open into the
vestibule by five orifices. In front is a large oval opening which communicates
with the scala vestibuli of the cochlea by a single orifice, apertura scalse vestibuli
cochleae.
The Semicircular canals are three bony canals, situated above and behind the
vestibule. They are of unequal length, compressed from side to side, and describe
the greater part of a circle. They measure about one-twentieth of an inch in
diameter, and each presents a dilatation at one end, called the ampulla, 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 is vertical in direction, its arch forming a
round projection on the anterior surface of the petrous bone. It forms about two-
thirds of a circle. Its outer extremity, which is ampullated, commences by a
distinct orifice in 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, and
opens by a common orifice with it in the back part of the vestibule.
The posterior semicircular canal, also vertical in direction, is directed back-
wards to the posterior surface of the petrous bone ; it is the longest of the three,
its ampullated end commencing at the lower and back part of the vestibule, its
opposite end joining the common canal already mentioned.
The external or horizontal canal is the shortest of the three, its arch being
COCHLEA. G39
directed outwards and backwards. Its ampullated end corresponds to the upper
and outer angle of the vestibule, just above the fenestra ovalis ; its opposite end
opens by a distinct orifice at the upper and back part of the vestibule.
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 forwards and outwards towards 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 apertures, for the passage of the cochlear branch of the
auditory nerve. It measures about a quarter of an inch in length, and its breadth
towards the base is about the same. It consists of a conical-shaped central axis,
the modiolus or columella; of a canal wound spirally round the axis for two
turns and a half, from the base to the apex ; and of a delicate lamina {lamina-
spiralis) contained within the canal, which follows its windings, and subdivides it
into two.
The central axis or modiolus is conical in form, and extends from the base to
the apex of the cochlea. Its base is broad, corresponds with the first turn of tho
cochlea, and is perforated by numerous orifices, which transmit filaments of
the cochlear branch of the auditory nerve ; the axis diminishes rapidly in size in
the second coil, and terminates within the last half-coil or cupola, in an expanded,
delicate, bony lamella, which resembles the half of a funnel, divided longitudinally,
and called the infundibulum • the broad part of this funnel is directed towards
the summit of the cochlea, and blends with the last half-turn of the spiral canal
of the cochlea, the cupola. The outer surface of the modiolus is formed of the
wall of the spiral canal, and is dense in structure ; but its centre is channelled, as
far as the last half-coil, by numerous branching canals, which transmit nervous
filaments in regular succession into the canal of the cochlea, or upon the surface
of the lamina spiralis. One of these, larger than the rest, occupies the centre of
the modiolus, and is named the tubulus centralis modioli; it extends from the base
to the extremity of the modiolus, and transmits a small nerve and artery (arteria
centralis modioli).
The spiral canal (fig. 317) takes two turns and a half round the modiolus. It
is about an inch and a half in length, measured along its outer wall ; and diminishes
Fig. 317.— The Cochlea laid open. (Enlarged.)
gradually in size from the base to the summit, where it terminates in a cul-de-
sac, the cupola, 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
towards the tympanum and vestibule, and presents three openings. One, the
fenestra rotunda, communicates with the tympanum; in the recent state, this
aperture is closed by a membrane, the membrana tympani secundaria. Another
aperture, of an oval form, enters the vestibule. The third is the aperture of the
640 ORGANS OF THE SENSES.
aquseductus cochlese, which leads to a minute funnel-shaped canal, which opens on
the basilar surface of the petrous bone, and transmits a small vein.
The interior of the spiral canal is divided into two passages {scalse) bj a thin,
osseous, and membranous lamina, which winds spirally round the modiolus. This
is the lamina spiralis, the essential part of the cochlea upon which the nerve
tubules are distributed. The osseous part of the spiral lamina -extends about half
way across the diameter of the spiral canal ; it is called the osseous zone. It
commences in the vestibule between the tympanic and vestibular opening of the
cochlea, and gradually becoming narrower in its course, terminates in a projecting
hook, the hamular process, just where the expansion of the infundibulum com-
mences. The lamina spiralis consists of two thin lamellae of bone, between which
are numerous canals for the passage of nervous filaments, which open chiefly
on the lower or tympanic surface. At the point where the osseous lamina is
attached to the modiolus, and following its windings, is a small canal, called by
Rosenthal, the canalis spiralis modioli. In the recent state, the osseous zone is
continued to the opposite wall of the canal by a membranous and muscular layer
(membranous zone), so as to form a complete partition in the tube of the cochlea.
Two passages or scalce are thus formed, by a division of the canal of the cochlea
into two. One, the scala tympani, is closed below by the membrane of the
fenestra rotunda; the other, the scala vestvbuU, communicates, by an oval
aperture, with the vestibule. Near the termination of the scala vestibuli, close
by the fenestra rotunda, is the orifice of the aquosductus cochleae. The scalae
communicate, at the apex of the cochlea, by an opening common to both, the
helicotrema, which exists in consequence of the deficiency of the lamina spiralis
in the last half-coil of the canal.
In structure, the membranous zone is a transparent glassy lamina, presenting
near its centre a number of minute transverse lines, which radiate outwards, ana
give it a fibrous appearance; and at its circumference, where it is connected with
the outer wall of the spiral canal, it is composed of a semi-transparent structure,
the Cochlearis muscle (Todd and Bowman), connective tissue (Kolliker).
The vestibular surface of the osseous portion of the lamina spiralis is covered,
for about the outer fifth of its surface, with a thin layer, resembling cartilage in
texture. It is described as the denticulate lamina (Todd and Bowman), from its
presenting a series of wedge-shaped teeth which form its free margin, and which
project into the vestibular scalar.
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 surface 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 heli-
cotrema into the scala tympani. Two delicate tubular processes are prolonged
along the aqueducts of the vestibule and cochlea, to the inner surface of the dura
mater. This membrane is continued across the fenestra ovalis and fenestra rotunda,
and consequently has no communication with the lining membrane of the tympa-
num. 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, perilymph (Blainville), or liquor Cotunnii.
In the vestibule and semicircular canals, it separates the osseous from the mem-
branous labyrinth; but in the cochlea it lines the two surfaces of the bony lamina
spiralis, and, being continued from its free margin across the canal to its outer
wall, forms the lamina spiralis membranacea, serving to complete the separation
between the two scalce.
The Membranous Labyrinth.
The Membranous Labyrinth (fig. 318) is a closed membranous sac, containing
d aid ; upon the wall of the sac, the ramifications of the auditory nerve are distributed.
MEMBRANOUS LABYRINTH.
641
It has the same general form as the vestibule and semicircular canals, in which it
is inclosed ; but is considerably smaller, and separated from their lining membrane
by the perilymph.
The vestibular 'portion consists of two sacs, the utricle and the saccule.
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
Fig. 318. — The Membranous Labyrinth detached. (Enlarged.)
Ofoliths
ixn iArcupA. tht ira
JK to Cochlea
fovea semi-elliptica. Numerous filaments of the auditory nerve are distributed on
the wall of1 this sac ; and its cavity communicates, behind, with the membranous
semicircular canals by five orifices.
The saccule is the smaller of the two vestibular sacs; it is globular in form, lies
in the fovea hemispherica, near the opening of the vestibular scala of the cochlea,
and receives numerous nervous filaments, which enter from the bottom of the
depression in which it is contained. Its cavity is apparently distinct from that
of the utricle.
The membranous semicircular canals are about one-third the diameter of the
osseous canals, but in number, shape, and general form they are precisely similar ;
they are hollow, and open by five orifices into the utricle, one being common to
two canals. Their ampullae are thicker than the rest of the tubes, and nearly fill
the cavities in which they are contained.
The membranous labyrinth is held in its position by the numerous nervous fila-
ments distributed to the utricle, the saccule, and to the ampulla of each canal.
These nerves enter the vestibule through the minute apertures on its inner wall.
Structure. The wall of the membranous labyrinth is semi-transparent, and con-
sists of three layers. The outer layer is a loose and flocculent tissue, containing
bloodvessels and numerous pigment-cells, analogous to those in the choroid. The
middle layer, thicker and more transparent, bears some resemblance to the hyaloid
membrane, but it presents in parts marks of longitudinal fibrillation and elongated
nuclei on the addition of acetic acid. The inner layer is formed of polygonal
nucleated epithelial cells, which secrete the endolymph.
41
642 ORGANS OF THE SENSES.
The endolyrnph {liquor Scarpa) is a limpid serous fluid, which fills the mem-
branous labyrinth ; in composition, it closely resembles the perilymph.
The otoliths are two small rounded bodies, consisting of a mass of minute
crystalline grains of carbonate of lime, held together in a mesh of delicate fibrous
tissue, and contained in the wall of the utricle and saccule, opposite the distribu-
tion of the nerves. A calcareous material is also, according to Bowman, sparingly
scattered in the cells lining the ampulla of each semicircular canal.
The Arteries of the labyrinth are the internal auditory from the basilar or
superior cerebellar, the stylo-mastoid from the posterior auricular, and, occasion-
ally, branches from the occipital. The internal auditory divides at the bottom of
the internal meatus into two branches, cochlear and vestibular.
The cochlear branch subdivides into from twelve to fourteen twigs, which
traverse the canals in the modiolus, and are distributed, in the form of a capillary
network, in the substance of the lamina spiralis.
The vestibular branches accompany the nerves, and are distributed, in the form
of a minute capillary network, in the substance of the membranous labyrinth.
The Veins of the vestibule and semicircular canals accompany the arteries, and,
receiving those of the cochlea at the base of the modiolus, terminate in the superior
petrosal sinus.
The Auditory nerve, the special nerve of the sense of hearing, divides, at the
bottom of the internal auditory meatus, into two branches, the cochlear and vesti-
bular. The trunk of the nerve, as well as the branches, contains numerous ganglion
cells with caudate prolongations.
The Vestibular nerve, the most posterior of the two, divides into three branches,
superior, middle, and inferior.
The superior vestibular branch, the largest, divides into numerous filaments,
which pass through minute openings at the upper and back part of the cul-de-sac
at the bottom of the meatus, and, entering the vestibule, are distributed to the
utricle, and to the ampulla of the external and superior semicircular canals.
The middle vestibular branch consists of numerous filaments, which enter the
vestibule by a smaller cluster of foramina, placed below those above mentioned,
and which correspond to the bottom of the fovea hemispherica ; they are dis-
tributed to the saccule.
The inferior and smallest branch passes backwards in a canal behind the
foramina for the nerves of the saccule, and is distributed to the ampulla of the
posterior semicircular canal.
The nervous filaments enter the ampullary enlargement at a deep depression seen
on their external surface, and a corresponding elevation is seen within, the nerve
fibres ending in loops, and in free extremities. In the utricle and saccule, the
nerve fibres spread out, some blending with the calcareous matter, others radiat-
ing on the inner surface of the wall of each cavity, becoming blended with a layer
of nucleated cells, and terminating in a thin fibrous film.
The Cochlear nerve divides into numerous filaments at the base of the modiolus,
which ascend along its canals, and then, bending outwards at right angles, pass
between the plates of the bony lamina spiralis, close to its tympanic surface.
Between the plates of the spiral lamina, the nerves form a plexus, which contains
ganglion cells ; and from the margin of the osseous zone, branches from this plexus
are distributed to the membranous part of the septum, where they are arranged in
small, conical-shaped bundles, parallel with one another. The filaments which
supply the apical portion of the lamina spiralis are conducted to this part through
the tubulus centralis modioli.
Organs of Digestion.
The Apparatus for the digestion of the food consists of the alimentary canal,
and of certain accessory organs.
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, which comprises the mouth, we find every provision
for the mechanical division of the Food (mastication), and for its admixture with
a peculiar fluid secreted by the salivary glands (insalivation) ; beyond this are the
pharynx and the oesophagus (the organs of deglutition), which convey the food
into the stomach, that part of the alimentary canal in which the principal chemi-
cal changes occur ; in that organ the reduction and solution of the food take place ;
by its admixture with the bile and pancreatic fluid, in the small intestines, the
nutritive principles of the food (the chyle) are separated from that portion which
passes into the large intestine, and which is expelled from the system.
Mouth.
Pharynx.
(Esophagus.
Stomach.
Teeth.
Alimentary Canal.
Small intestine
Large intestine
Accessory Organs.
{Parotid.
Submaxillary.
Sublingual.
Duodenum.
Jejunum.
Ileum.
Caecum.
Colon.
Eectum.
Liver.
Pancreas.
Spleen.
The Mouth (fig. 319) is placed at the commencement of the alimentary canal;
it is a nearly oval-shaped cavity, in which the mastication of the food takes place.
It is bounded, in front, by the lips ; laterally, by the cheeks and alveolar process
of the upper and lower jaw ; above, by the hard palate and teeth of the upper
jaw ; below, by the tongue, the mucous membrane stretched between the under
surface of this organ and the inner surface of the jaws, and by the teeth of the
lower jaw; behind, by the soft palate and fauces.
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 fauces behind ; it
is of a pink rose tinge during life, and very thick where it covers the hard parts
bounding this cavity.
The Lips are two fleshy folds, which surround the orifice of the mouth, formed
externally of integument, internally of mucous membrane, between which are found
the Orbicularis oris muscle, the coronary vessels, some nerves, areolar tissue, fat,
and numerous small labial glands. The inner surface of each lip is connected in
the middle line to the gum of the corresponding jaw by a fold of mucous mem-
brane, the frsenum labii superioris and frsenum ktbii inferioris, the former being
the larger of the two.
The labial glands are situated between the mucous membrane and the Orbicularis
646
644
ORGANS OF DIGESTION.
oris, round the orifice of the mouth. They are rounded in form, about the size
of a small pea, their ducts opening by small orifices upon the mucous membrane.
In structure, they resemble the other salivary glands.
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 mem-
brane ; and, between the two, of a muscular stratum, besides a large quantity of
fat, areolar tissue, vessels, nerves, and buccal glands.
The mucous membrane lining the cheek is reflected above and below upon the
gums, and 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
Fig. 319. — Sectional View of the Nose, Mouth, Pharynx, etc.
K) fie nitty of
A'atai duct
Bristle
pa**ed through
i's duct
which presents the minute aperture of the duct of the parotid gland. The prin-
cipal muscle of the cheek is the Buccinator; but numerous others enter into its
formation, viz., the Zygomatic!, Masseter, and the Platysma myoides.
The buccal glands are placed between the mucous membrane and Buccinator
muscle : they are similar in structure to, but smaller than, the labial glands. Two
or three, of larger size than the rest, are placed between the Masseter and
Buccinator muscles; their ducts open into the mouth, opposite the last molar
tooth. They are called molar glands.
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.
THE TEETH.
645
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.
The human subject is provided with two sets of teeth, which make their ap-
pearance at different periods of life. The first set appear in childhood, and are
called the temporary, deciduous, or milk teeth. The second set, which also appear
at an early period, continue until old age, and are named permanent.
The temporary teeth are twenty in number ; four incisors, two canine, and four
molars, in each jaw.
The permanent teeth are thirty- two in number ; four incisors (two central and
two lateral), two canine, four bicuspids, and six molars, in each jaw.
General characters. Each tooth consists of three portions; the crown or body,
Fig. 320.— The Permanent Teeth. External View.
Jfolarf
Wiiclom t„nh.
Uj>2>er Juw
Bicuspid* Canine TiusitoT*
FU71J
Keck
JLotver Jaw
which projects above the gum ; the root or fang, entirely concealed within the
alveolus ; and the neck, the constricted portion between the other two.
The roots of the teeth are firmly implanted within the alveoli : these depressions
are lined with periosteum, which is reflected on to the tooth at the point of the
fang, and covers it as far as the neck. At the margin of the alveolus, the peri-
osteum becomes continuous with the fibrous structure of the gums.
G46 ORGANS OF DIGESTION.
Permanent Teeth.
The Incisors or cutting teeth are so named from their presenting a sharp, cut-
ting edge, adapted for cutting the food. They are eight in number, and form the
four front teeth in each jaw.
The crown is directed vertically, is wedge-like in form, being bevelled at the
expense of its posterior surface, so as to terminate in a sharp, horizontal cutting
edge, which, before being subject to attrition, presents three small prominent
points. It is convex, smooth, and highly polished in front ; slightly concave be-
hind, where it is frequently marked by slight longitudinal furrows.
The neck is constricted.
The fang is long, single, conical, transversely flattened, thicker before than
behind, and slightly grooved on each side in the longitudinal direction.
The incisors of the upper jaw are altogether larger and stronger than those
of the lower jaw. They are directed obliquely downwards and forwards. The
two central ones are larger than the two lateral, and their free edges sharp and
chisel-like, being bevelled at the expense of their posterior edge ; the root is more
rounded.
The incisors of the lower jaw are smaller than the upper; the two central
ones are smaller than the two lateral, and are the smallest of all the incisor
teeth.
The Canine Teeth (cuspidati) are four in number, two in the upper, and two
in the lower jaw; one being placed behind each lateral incisor. They are larger
and stronger than the incisors, especially the root, which sinks deeply into the jaw,
and causes a well-marked prominence upon its surface.
The crown is large and conical, very convex in front, a little hollowed and un-
even posteriorly, and tapering to a blunted point or cusp which rises above the
level fcf the other teeth.
The root is single, but longer and thicker than that of the incisors, conical in
form, compressed laterally, and marked by a slight groove on each side.
The upper canine teeth (vulgarly called eye-teeth) are larger and longer than the
two lower, and situated a little behind them.
The lower canine teeth are placed in front of the upper, so that their summits
correspond to the interval between the upper canine teeth and the neighboring
incisor.
The Bicuspid Teeth (small or false molars) are eight in number, four in each
jaw, two being placed immediately behind each of the canine teeth. They are
smaller and shorter than the canine.
The crown is compressed from without inwards, and surmounted by two pyra-
midal eminences or cusps separated by a groove ; hence their name, bicuspidate.
The outer of these cusps is larger and more prominent than the inner.
The neck is oval.
The root is generally single, compressed, and presents a tendency to become
double, as seen from the deep groove on each side. The apex is generally bifid.
The upper bicusjnds are larger, and present a greater tendency to the division
of their roots than the lower; this is especially marked in the second upper
bicuspid.
The Molar Teeth {multicuspidati, true or large molars) are the largest of the
permanent set, and are adapted, from the great breadth of their crowns, for grind-
ing and pounding the food. They are twelve in number, six in each jaw, three
being placed behind each of the posterior bicuspids.
The crown is nearly cubical in form, rounded on each of its lateral surfaces,
flattened in front and behind ; the upper surface being surmounted by four or five
tubercles or cusps (four in the upper, five in the lower molars) separated from
each other by a crucial depression; hence their name, multicuspidati.
THE TEETH. G4V
The neck is distinct, large, and rounded.
The root is subdivided into from two to five fangs, each of which presents an
aperture at its summit.
The first molar tooth is the largest and broadest of all; its crown has usually
five cusps, three outer and two inner. In the upper jaw, the root consists of
three fangs, widely separated from one another, two being external, the other
internal. The latter is the largest and the longest, slightly grooved, and some-
times bifid. In the lower jaw, the root consists of two fangs, one being placed in
front, the other behind ; they are both compressed from before backwards, and
grooved on their contiguous faces, indicating a tendency to division.
The second molar is a little smaller than the first.
The crown has four cusps in the upper, and five in the lower jaw.
The root has three fangs in the upper jaw, and two in the lower, the characters
of which are similar to the preceding tooth.
The third molar tooth is called the wisdom tooth (dens sapientise), from its late
appearance through the gum. It is smaller than the others, and its axis is directed
inwards.
The crown is small and rounded, and furnished with three tubercles.
The root is generally single, short, conical, slightly curved, and grooved so as
to present traces of a subdivision into three fangs in the upper, and two in the
lower jaw.
Temporary Teeth.
The temporary or milk teeth are smaller, but resemble in form those of the
permanent set. The hinder of the two temporary molars is the largest of all the
Fig. 321.— The Temporary or Milk Teeth. External View.
Zjoiver J u w
Canine Inciters
milk teeth, and is succeeded by the second permanent bicuspid. The first upper
molar has only three cusps, two external, one internal ; the second upper molar
has four cusps. The first lower molar has four cusps ; the second lower molar
has five. The fangs 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.
648
ORGANS OF DIGESTION".
Fig. 322.— Vertical
Section of a Molar
Tooth.
T-Cr
Neck
-J^a
Fig. 323.— Vertical Section
of a Bicuspid Tooth.
Magnified.
Structure of the Teeth.
Structure. On making a vertical section of a tooth (fig. 322), a hollow cavity
will be found in the interior. This cavity is situated at the base of the crown, and
is continuous with a canal which traverses the centre of
each fang, and opens by a minute orifice at its extremity.
The shape of the cavity corresponds somewhat with that of
the tooth : it forms what is called the pulp cavity, and con-
tains a soft, highly vascular, and sensitive substance, the
dental pulp. The pulp is richly supplied with vessels and
nerves, which enter the cavity through the small aperture at
the point of each fang.
The solid portion of the tooth consists of three distinct
structures, viz., ivory (tooth-bone or dentine), which forms
the larger portion of the tooth ; enamel, which covers the
exposed part or crown ; and the cortical substance or cement
(crusta petrosa), which is disposed as a thin layer on the surface of the fang.
The Ivory or dentine (fig. 323) forms the principal mass of a tooth ; in its
central part is the cavity inclosing the pulp. It is a modification of the osseous
tisue, from which it differs, however, in structure and chemical composition. On
examination with the microscope, it is seen to consist
of a number of minute wavy and branching tubes,
having distinct parietes. They are called the dental
tubuli, and are imbedded in a dense homogeneous sub-
stance, the intertubular tissue.
The dental tubuli are placed parallel with one ano-
ther, and open at their inner ends into the pulp cavity.
They pursue a wavy and undulating course towards
the periphery. The direction of these tubes varies;
they are vertical in the upper portion of the crown,
oblique in the neck and upper part of the root, and
towards the lower part of the root they are inclined
downwards. The tubuli, at their commencement,
are about 75^71 °f an mcn in diameter; in their
course they divide and subdivide dichotomously,
so as to give to the cut surface of the dentine a striated
appearance. From the sides of the tubes, especially
in the fang, ramifications of extreme minuteness are
given off, which join together in loops in the inter-
tubular substance, or terminate in small dilatations, from
which branches are given off. Near the periphery of
the dentine, the finer ramifications of the tubuli ter-
minate in a somewhat similar manner. In the fang,
these ramifications occasionally pass into the crusta
petrosa. The dental tubuli have comparatively thick
walls, and contain, according to Mr. Tomes, slender cylindrical prolongations of
the pulp-tissue.
The intertubular substance is translucent, finely granular, 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 is described
by Henle as consisting of bundles of pale, granular, flattened fibres, running
parallel with the tubes ; but by Mr. Nasmyth as consisting of a mass of brick-
shaped cells surrounding the tubules. By Czermak and Mr. Salter it is supposed
to consist of laminae which run parallel with the pulp cavity, across the direction
of the tubes.
Chemical Composition. According to Berzelius and Bibra, dentine consists of
28 parts of animal, and 72 of earthy matter. The animal matter is resolvable by
Fang
DEVELOPMENT OF THE TEETH. 049
boiling into gelatin. The earthy matter consists of phosphate of lime, carbonate
of lime, a trace of fluoride of calcium, and phosphate of magnesia, and other salts.
The Enamel 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 fang.
It is thickest on the grinding surface of the crown, until worn away by attrition,
and becomes thinner towards the neck. It consists of a congeries of minute hexa-
gonal rods. They lie parallel with one another, resting by one extremity upon
the dentine, which presents a number of minute depressions for their reception ;
the outer extremity forming the free surface of the crown. These fibres are
directed vertically on the summit of the crown, horizontally at the sides ; they are
about the -gs^-ir of an inch in diameter, and pursue a more or less wravy course,
which gives to the cut surface of the enamel a series of concentric lines.
Numerous minute interstices intervene between the enamel-fibres near their
dentinal surface, a provision calculated to allow of the permeation of fluids from
the dentinal tubuli into the substance of the enamel. The enamel-rods consist of
solid hexagonal or four-sided prisms, connected by their surfaces and ends, and filled
with calcareous matter. If the latter is removed, by weak acid, from newly-formed
or growing enamel, it will be found to present a network of delicate prismatic cells
of animal matter.
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 phosphate of lime, with traces of fluoride of calcium, carbonate of lime, phos-
phate of magnesia and other salts.
The Cortical Substance or cement (crusta petrosa) is disposed as a thin
layer on the roots of the teeth, from the termination of the enamel, as far as the
apex of the fang, where it is usually very thick. In structure and chemical com-
position, it resembles bone. It contains, sparingly, the lacunae and canaliculi which
characterize true bone ; those lacunas placed near the surface have the canaliculi
radiating from the side of the lacunae towards the periodontal membrane ; and
those more deeply placed, join with the adjacent dental tubuli. In the thicker
portions of the crusta petrosa, the lamellae and Haversian canals peculiar to bone
are also found. As age advances, the cementum 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 (osieo-dcntine, Owen ; secondary dentine,
Tomes). It appears to be formed by a slow conversion of the dental pulp, which
shrinks, or even disappears.
Development of the Teeth (figs. 324 to 329).
According to the observations of Arnold and Groodsir, the teeth are developed
from the mucous membrane covering the edges of the maxillary arches. About
the sixth week of foetal life (fig. 324), the mucous membrane covering the edge of
the upper jaw, presents a semicircular depression or groove ; this is the primitive
dental groove (Goodsir), from the floor of which the germs of the ten deciduous
or milk-teeth are developed. The germ of each tooth is formed by a conical
elevation or papilla of mucous membrane (fig. 325), which constitutes the rudimen-
tary pulp of a milk-tooth. The germs of the milk-teeth make their appearance in
the following order : at the seventh week, the germ of the first deciduous molar
of the upper jaw appears ; at the eighth week, that for the canine tooth is deve-
loped ; the two incisor papillae appear about the ninth week (the central preceding
the lateral) ; lastly, the second molar papilla is seen at the tenth week, behind the
anterior molar. The teeth of the lower jaw appear rather later, the first molar
papilla being only just visible at the seventh week; and the tenth papilla not
being developed before the eleventh week. This completes the first or papillary
stage of their development.
650
ORGANS OF DIGESTION.
Development of Teeth.
Flo. 224.
Frimifive .Dental Groove* *
r I c . 325.
TaJiilla.in-Gtr-m. ofMXf^tootb
He. 327.
fie. 328.
r I C . 329.
Srlc/dian ofMM.'totrth
£*finusitnt IcuUt
The dental groove now becomes contracted,
its margins thickened and prominent, and the
groove is converted into follicles for the re-
ception of the papillae, by the growth of mem-
branous septa, which pass across the groove
between its borders (fig. 326). The follicles
by this means become the alveoli, lined by
periosteum, from the bottom of which a process
of the mucous membrane of the gum rises,
which is the germ of the future tooth. The
follicle for the first molar is complete about the
tenth week ; the canine follows next, succeeded
by the follicles for the incisors, which are com-
pleted about the eleventh or twelfth week ; and,
lastly, the follicle of the posterior deciduous
molar is completed about the fourteenth week.
These changes constitute the second or follicu-
lar stage.
About the thirteenth week, the papilla? begin
to grow rapidly, project from the follicles, and
assume a form corresponding with that of the
future teeth ; the follicles soon become deeper,
and from their margins small membranous
processes or opercula are developed, which,
meeting, unite and form a lid to the now closed
cavity (fig. 327). These processes correspond
in shape to the form of the crown of the
tooth, and in number to the tubercles on its
surface. The follicles of the incisor teeth have
two opercula, the canine three, and the molars
four or five each. The follicles are thus con-
verted into dental sacs, and the contained
papillae become pulps. The lips of the dental
groove gradually advance over the follicles from
behind forwards, and, uniting, gradually ob-
literate it. This completes the third or saccular
stage, which takes place about the end of the
fifteenth week.
The deep portion of the primitive dental
groove is now closed-in; but the more super-
ficial portion, near the surface of the gum,
still remains open ; it is called, by Mr. Goodsir,
the secondary dental groove; from it are
developed the ten anterior permanent teeth.
About the fourteenth week, certain lunated
depressions are formed, one behind each of
the sacs of the rudimentary milk-teeth. They
are ten in number in each jaw, and are
formed successively from before backwards;
they are the rudimentary follicles of the four
permanent incisors, the two canine, and the
four bicuspids. As the secondary dental groove
closes in, these follicles become closed cavities of
reserve (fig. 327). The cavities soon elongate,
and recede from the surface into the substance
of the gum, behind the sacs of the deciduous
teeth, and a papilla projects from the bottom of
DEVELOPMENT OF THE TEETH. 651
each, which is the germ of the permanent tooth ; at the same time, one or more
operculse are developed from the sides of the cavity ; and these, uniting, divide it
into two portions ; the lower portion containing the papilla of the permanent
tooth, the upper narrower portion becoming gradually contracted in the same way
that the primitive dental groove was obliterated over the sacs of the deciduous
teeth (fig. 328).
The six posterior permanent teeth in each jaw, three on each side, arise from
successive extensions backwards of the back part of the primitive dental
groove. During the fourth month, that portion of the dental groove which lies
behind the last temporary molar follicle remains open, and from it is developed
the papilla, the rudiment of the first permanent molar. The follicle in which it
is contained becomes closed by its operculum, and the upper part of the now-
formed sac elongates backwards to form a cavity of reserve, in which the papilla
of the second permanent molar appears at the seventh month after birth. After
a considerable interval, during which the sacs of the first and second permanent
molars have considerably increased in size, the remainder of the cavity of reserve
presents for the last time a series of changes similar to the preceding, and gives
rise to the sac and papilla of the wisdom-tooth, which appears at the sixth
year.
Growth of the Teeth. As soon as the dental sacs are formed by the closing-in
of the follicles, they gradually enlarge, as well as their contained papillae. Each
sac consists of two layers ; an internal, highly vascular layer, lined by epithelium ;
and an external or areolo-fibrous membrane, analogous to the corium of the mucous
membrane.
The dental pulps soon become moulded to the form of the future teeth, and are
adherent by their bases to the bottom of the dental sacs ; in the case of the molars,
the base of the pulp is divided into two or more portions, which form the future
fangs. During the fourth or fifth month of fcetal life, a thin lamina or cap of dentine
is formed on the most prominent point of the pulp of all the milk-teeth. In the
incisor and canine teeth, this newly-formed lamina has the form of a hollow cone ;
in the molar teeth, as many separate laminas are found as there are eminences upon
its crown. These lamina) grow at the expense of the pulp-substance, increasing
in breadth by a growth round their margins, and in thickness by a similar forma-
tion in its substance ; the separate cones (if a molar tooth) ultimately coalesce, and
the crown is completely formed. The pulp now becomes constricted, so as to form
the cervix ; and the remaining portion becomes narrow and elongated, to form the
fang. The growth of dentine takes place from the surface towards the interior,
until nothing but the small cavitas pulpse remains in the centre of the tooth, com-
municating by the aperture left at the point of each fang, with the dental vessels
and nerves.
As soon as the formation of the dentine has commenced, there is developed
from the inner wall of the dental sac, a soft pulpy mass, the enamel organ, which
is intimately united to the surface of the dental pulp, or its cap of dentine. It
consists of a mesh of fibres, elastic and spongy, containing within its reticulations
fluid albumen; and at the point of junction of each fibre, a transparent nucleus is
visible. The surface towards the dentinal pulp is covered by a layer of elongated
nucleated cells, the enamel membrane. The deposition of the enamel takes place
on the outer surface of the cap of dentine.
The cementum appears to be formed, at a later period of life, by the periodontal
membrane, extending from the margin of the enamel downwards.
Eruption. When the calcification of the different tissues of the tooth is suffi-
ciently advanced to enable it to bear the pressure to which it will be afterwards
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 (fig. 329). Concurrent with
this, the septa between the dental sacs, at first fibrous in structure, soon ossify, and
G52 * ORGANS OF DIGESTION.
constitute the alveoli ; these firmly embrace the necks of the teeth, and afford them
a solid basis of support.
The eruption of the temporary teeth commences at the seventh month, and is
complete about the end of the second year, those of the lower jaw preceding the
upper.
The periods for the eruption of the temporary set are : —
7th month, central incisors. 14th to 20th month, canine.
7th to 10th month, lateral incisors. 18th to 36th month, posterior molars.
12th to 14th month, anterior molars.
Calcification of the permanent teeth commences a little before birth, and pro-
ceeds in the following order in the upper jaw, in the lower jaw appearing a little
earlier : — First molar, five or six months ; the central incisor a little later ; lateral
incisors and canine, about the eighth or ninth month ; the bicuspids at the second
year ; second molar,- five or six years ; wisdom-tooth, about twelve years.
Previous to the permanent teeth penetrating the gum, the bony partitions
separating their sacs from the deciduous teeth are absorbed, the fangs of the
temporary teeth disappear, and the permanent teeth become placed under the
loose crowns of the deciduous teeth ; the latter finally become detached, when the
permanent teeth take their place in the mouth.
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 : —
6| years, first molars. 10th year, second bicuspid.
7th year, two middle incisors. 11th to 12th year, canine.
8th year, two lateral incisors. 12th to 13th year, second molars.
9th year, first bicuspid. 17th to 21st year, wisdom-teeth.
The Palate.
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 is bounded in front and at the sides by the alveolar arches
and gums ; behind, it is continuous with the soft palate. It is covered by a dense
structure, formed by the periosteum and mucous membrane of the mouth, which
are intimately adherent. Along the middle line is a linear ridge or raphe, which
terminates anteriorly in a small papilla, corresponding with the inferior opening
of the anterior palatine fossa. This papilla receives filaments from the naso-
palatine and anterior palatine nerves. On either side and in front of the raphe,
the mucous membrane is thick, pale in color, and corrugated ; behind, it is thin,
smooth, and of a deeper color ; it is covered with squamous epithelium, and fur-
nished with numerous glands (palatal glands), which lie between the mucous
membrane and the surface of the bone.
The soft palate or Velum pendulum palati is a movable fold, suspended from the
posterior border of the hard palate, forming an incomplete septum between the
mouth and pharynx. It consists of a fold of mucous membrane, inclosing mus-
cular fibres, an aponeurosis, vessels, nerves, and mucous glands. "When occupy-
ing its usual position (a relaxed pendent state), its anterior 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 posterior
surface is convex, and continuous with the mucous membrane covering the floor
of the posterior nares. Its upper border is attached to the posterior margin of
the hard palate, and its sides are blended with the pharynx. Its lower border is
free.
Hanging from the middle of its lower border is a small conical-shaped pendu-
lous process, the uvula; and arching outwards and downwards from the base of
PALATE — SALIVARY GLANDS. 653
the uvula on each side, are two curved folds of mucous membrane, containing
muscular fibres, called the arches or pillars of the soft palate.
The anterior pillar runs downwards and forwards to the side of the base of the
tongue, and is formed by the projection of the Palato-glossus muscle, covered by
mucous membrane.
The posterior filter* are more closely approximated and larger than the anterior;
they run downwards and backwards to the sides of the pharynx, and are formed
by the projection of the Palato-pharyngei muscles, covered by mucous membrane.
The anterior and posterior 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. It is bounded above by the free margin of the palate ;
below, by the tongue ; and on each side, by the pillars of the soft palate and
tonsils.
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 it is columnar and ciliated. The palatine glands form a continuous layer
on its posterior surface and round the uvula.
The aponeurosis of the soft palate is a thin but firm fibrous layer, attached above
to the hard palate, and becoming thinner towards the free margin of the velum.
It is blended with the aponeurotic tendon of the Tensor palati muscle.
The muscles of the soft palate are five on each side ; the Levator palati, Tensor
palati, Palato-glossus, Palato-pharyngeus, and the Azygos uvulae.
The tonsils {amygdalse) are two glandular organs, 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.
Externally, the tonsil is in relation with the inner surface of the Superior con-
strictor, and with the internal carotid and ascending pharyngeal arteries, and
corresponds to the angle of the lower jaw. Its inner surface presents from
twelve to fifteen orifices, leading into small recesses, from which numerous follicles
branch out into the substance of the gland. These follicles are lined by a con-
tinuation of the mucous membrane of the pharynx, covered with epithelium, their
walls being formed by a layer of closed capsules imbedded in the submucous
tissue. These capsules are analogous to those of Peyer's glands ; they contain a
thick grayish secretion.
The arteries supplying the tonsil are the dorsalis linguae from the lingual,
the ascending palatine and tonsillar from the facial, the ascending pharyngeal
from the external carotid, and the descending palatine branch of the internal
maxillary.
The veins terminate in the tonsillar plexus, on the outer side of the tonsil.
The nerves are derived from the fifth, and from the glossopharyngeal.
The Salivaey Glands.
The principal salivary glands communicating with the mouth, and pouring their
secretion into its cavity, are the parotid, submaxillary, and sublingual.
The Parotid gland (fig. 330), so called from being placed near the ear (*apa,
near ; ovj, wro{, 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, imme-
diately below and in front of the external ear. It is limited above by the zygoma;
below, by the angle of the jaw, and by an imaginary line drawn between it and
the Sterno-mastoid muscle ; 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
former.
Its anterior surface is grooved to embrace the posterior margin of the ramus of
the lower jaw, and advances forwards beneath the ramus, between the two ptery-
654
ORGANS OF DIGESTION.
goid muscles. Its outer surface, slightly lobulated, is covered by the integument
and fascia, and lias one or two lymphatic glands resting on it. Its inner surface
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. Imbedded in its substance is the external carotid, which ascends behind
the ramus of the jaw ; the posterior auricular artery emerges from it behind ; the
temporal artery above; the transverse facial in front; and the internal maxillary
winds through it inwards, 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 it with the internal jugular, also traversing the
gland. It is traversed, from before backwards, by the facial nerve and its
branches, which emerge at its anterior border ; the great auricular nerve pierces
the gland to join the facial, and the temporal branch of the inferior maxillary
nerve lies above the upper part of the gland. The internal carotid artery and
internal jugular vein lie close to its deep surface.
Steno's duct, the duct of the parotid gland, is about two inches and a half in
length. It commences upon the inner surface of the cheek by a small orifice,
Fig. 330.— The Salivary Gland.
opposite the second molar tooth of the upper jaw ; running obliquely for a short
distance beneath the mucous membrane, it pierces the Buccinator muscle, and
crosses the Masseter to the anterior border of the gland, in the substance of
which it subdivides into numerous branches. The direction of the duct corre-
sponds to a line drawn across the face about a finger's breadth below the zygoma,
from the lower part of the concha to midway between the free margin of the
upper lip and the ala of the nose. While crossing the Masseter, it receives the
duct of a small detached portion of the gland, socia parotidis, which occasionally
exists as a separate lobe, just beneath the zygomatic arch. The parotid duct is
SALIVARY GLANDS. Wfl
dense, of considerable thickness, and its canal is about tlie size of a crow-quill ; it
consists of an external or fibrous coat, of considerable density, containing con- .
tractile fibres, and of an internal or mucous coat, lined with columnar epithelium.
Vessels and Nerves. The arteries supplying the parotid gland are derived from
the external carotid, and from the branches of that vessel in or near its substance.
The veins follow a similar course. The lymphatics terminate in the superficial
and deep cervical glands, passing in their course through two or three lymphatic
glands, placed on its surface and in its substance. The nerves are derived from
the carotid plexus of the sympathetic, the facial, superficial, temporal, and great
auricular nerves.
The Submaxillary 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. It is covered by the integument, Platysma, deep cervical fascia, and
the body of the lower jaw, corresponding to a depression on its inner surface,
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 ; 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 in a groove in its posterior and
upper border.
Wharton's duct, the duct of the submaxillary gland, is about two inches in
length, and its walls much thinner than those of the parotid duct. It commences
by a narrow orifice on the summit of a small papilla, at the side of the fraenum
linguae. Passing between the sublingual gland and the Genio-hyo-glossus mus-
cle, it runs backwards and outwards between the Mylo-hyoid, and the Hyo-glossus
and Genio-hyo-glossus muscles, and beneath the gustatory nerve, to the deep por-
tion of the gland, where it divides into numerous branches.
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 nerves
are derived from the submaxillary ganglion, from the mylo-hyoid branch of the
inferior dental, and from the sympathetic.
The Sublingual gland is the smallest of the salivary glands. It is situated
beneath the mucous membrane of the floor of the mouth, on either 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-rryoid 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 (ductus Biviniani), from eight to twenty in number, open sepa-
rately into the mouth, on the elevated crest of mucous membrane, caused by the
projection of the gland, on either side of the fraenum linguae. One or more join
to form a tube which opens into the Whartonian duct ; it is called the duct of
Bartholin^.
Vessels and Nerves. The sublingual gland is supplied with blood from the sub-
lingual and submental arteries. Its nerves are derived from the gustatory.
Structure. The salivary are conglomerate 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 numerous closed vesicles, which open
into a common duct ; the wall of each vesicle is formed of a delicate basement
membrane, lined by epithelium, and covered on its outer surface with a dense capil-
lary network. In the submaxillary and sublingual glands, the lobes are larger
and more loosely united than in the parotid.
656 ORGANS OF DIGESTION.
The Pharynx
The Pharynx is that part of the alimentary canal which is placed behind the
nose, mouth, and larynx. It is a musculo-membranous sac, somewhat conical in
form, with the base upwards, and the apex downwards, extending from the under
surface of the skull to the cricoid cartilage in front, and the fifth cervical vertebra
behind.
The pharynx is about four inches and a half in length, and broader in the
transverse 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 limited, above, by the basilar process of the occipital bone;
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 Eecti capitis antici muscles ; anteriorly, it is incomplete, and is attached
in succession to the internal pterygoid plate, the pterygo-maxillary ligament, the
lower jaw, the tongue, hyoid bone, and larynx ; laterally, it is connected to the
styloid processes and their muscles, and is in contact with the common and
internal carotid arteries, the internal jugular veins, and the eighth, ninth, and
sympathetic nerves, and, above, with a small part of the Internal pterygoid
muscles.
It has seven openings communicating with it; 'the two posterior nares, the two
Eustachian tubes, the mouth, larynx, and oesophagus.
The posterior nares are the two large apertures situated at the upper part of
the anterior wall of the pharynx.
The two Eustachian tubes open one at each side of the upper part of the pharynx,
at the back part of the inferior meatus. Below the nasal fossae are the posterior
surface of the soft palate and uvula, the large aperture of the mouth, the base of
the tongue, the epiglottis, and the cordiform opening of the larynx.
The oesophageal opening is the lower contracted portion of the pharynx.
Structure. The pharynx is composed of three coats ; a mucous coat, a muscular
layer, and a fibrous coat.
The fibrous coat is situated between the mucous and muscular layers, and is
called the pharyngeal aponeurosis. It is thick above, where the muscular fibres
are wanting, and firmly connected to the basilar process of the occipital and petrous
portion of the temporal bones. As it descends, it diminishes in thickness, and is
gradually lost.
The mucous coat is continuous with that lining the Eustachian tubes, the nares,
the mouth, and the larynx. It is covered by columnar ciliated epithelium, as low
down as a level with the floor of the nares ; below that point, it is of the squamous
variety.
The muscular coat has been already described (p. 262).
The pharyngeal glands are of two kinds, the simple or compound follicular,
which are found in considerable numbers beneath the mucous membrane, through-
out the entire pharynx ; and the racemose, which are especially numerous at the
upper part of the pharynx, and form a thick layer, across the back of the fauces,
between the two Eustachian tubes.
The (Esophagus.
The (Esophagus is a membranous canal, about nine inches in length, extending
from the pharynx to the stomach. It commences at the lower border of the
cricoid cartilage, opposite the fifth cervical vertebra, descends along the front of
the spine, through the posterior mediastinum, passes through the Diaphragm, and,
entering the abdomen, terminates at the cardiac orifice of the stomach, opposite the
ninth dorsal vertebra. The general direction of the oesophagus is vertical ; but it
presents two or three slight curvatures in its course. At its commencement, it is
(ESOPHAGUS. 65T
placed in the median line ; but it inclines to the left side at the root of the neck,
gradually passes to the middle line again, and, finally, again deviates to the left, as
it passes forwards to the oesophageal opening of the Diaphragm. 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 ali-
mentary canal, being most contracted at its commencement, and at the point where
it passes through the Diaphragm.
Relations. In the neck, the oesophagus is in relation, in front, with the trachea ;
and, at the lower part of the neck, where it projects to the left side, with the
thyroid gland and thoracic duct ; behind, it rests upon the vertebral column
and Longus colli muscle ; on each side, it is in relation with the common carotid
artery (especially the left, as it inclines to that side), and part of the lateral lobes of
the thyroid gland ; the recurrent laryngeal 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
passes across the left side of the transverse part of the aortic arch, descends in
the posterior mediastinum, along the right side of the aorta, until near the
Diaphragm, where it passes in front and a little to the left of this vessel, previous
to entering the abdomen. It is in relation, in front, with the trachea, the arch
of the aorta, the left bronchus, and the posterior surface of the pericardium;
behind, it rests upon the vertebral column, the Longus colli, and +,he intercostal
vessels ; below, near the Diaphragm, upon the front of the aorta ; laterally,
it is covered by the pleurae ; the vena azygos major lies on the right, and the
descending aorta on the left side. The pneumogastric nerves descend in close
contact with it, the right nerve passing down behind, and the left nerve in front
of it.
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 becomes of importance that its direction and 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 peri-
cardium.
The student should also remember that contraction of the oesophagus, and consequent symp-
toms of stricture, are occasionally produced by an aneurism of some part of the aorta pressing
upon this tube. In such a case, the passage of a bougie could only hasten the fatal issue.
It occasionally happens that a foreign body becomes impacted in the oesophagus, which can
neither be brought upwards nor moved downwards. When all ordinary means for its removal
have failed, excision is the only resource. This, of course, can only be performed when it is not
very low down. If the foreign body is allowed to remain, extensive inflammation and ulceration
of the oesophagus may ensue. In one case with which I am acquainted, the foreign body ulti-
mately penetrated the intervertebral substance, and destroyed life by inflammation of the mem-
branes and substance of the cord.
The operation of cesophagotomy is thus performed : — The patient being placed upon his back,
with the head and shoulders slightly elevated, an incision, about four inches in length, should be
made on the left side of the trachea, from the thyroid cartilage downwards, dividing the skin and
Platysma. The edges of the wound being separated, the Omo-hyoid muscle and the fibres of the
Sterno-hyoid and Sterno-thyroid muscles must be drawn inwards ; the sheath of the carotid
vessels being exposed should be drawn outwards, and retained in that position by retractors; the
oesophagus will then be exposed, and should be divided over the foreign body, which should then
be removed. Great care is necessary to avoid wounding the thyroid vessels, the thyroid gland,
and the laryngeal nerves.
Structure. The oesophagus has three coats ; an external or muscular, a middle
or cellular, and an internal or mucous coat.
The muscular coat is composed of two planes of fibres of considerable thick-
ness, an external longitudinal and an internal circular.
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, continuous with the fibres
of the Inferior constrictor; as they descend they blend together, and form a
uniform layer, which covers the outer surface of the tube.
42
658
ORGANS OF DIGESTION.
The circular fibres are continuous above with the Inferior constrictor : thei r
direction is transverse at the upper and lower parts of the tube, but oblique in
the central part.
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 entirely of the
involuntary muscular fibre.
The cellular coat connects loosely the mucous and muscular coats.
The mucous coat is thick, of a reddish color above, and pale below. It is
loosely connected with the muscular coat, and disposed in longitudinal plicas,
which disappear on distension of the tube. Its surface is studded with minute
papillae, and it is covered throughout with a thick layer of squamous epithelium.
The oesophageal glands are numerous small compound glands, scattered through-
out the tube ; they are lodged in the submucous tissue, and open upon the surface
by a long excretory duct. They are most numerous at the lower part of the tube,
where they form a ring round the cardiac orifice.
The Abdomen".
The Abdomen is the largest cavity of the trunk of the body, and is separated,
below, from the pelvic cavity by the brim of the pelvis. It is of an oval form, the
extremities of the oval being directed upwards and downwards ; it is wider above
than below, and measures more in the vertical than in the transverse diameter.
Fig.
331. — The Regions of the Abdomen and their Contents.
(Edge of Costal Cartilages in dotted outline.)
Boundaries. It is bounded, in front and at the sides, by the lower ribs, the
Transversales muscles, and venter ilii ; behind, by the vertebral column, and the
Psoae and Quadrati lumborum muscles ; above, by the Diaphragm ; below, by the
ABDOMEN.
659
brim of the pelvis. The muscles forming the boundaries of this cavity are lined
upon their inner surface by a layer of fascia, differently named according to the
part to which it is attached.
This cavity contains the greater part of the alimentary canal, some of the
accessory organs4 to digestion, the liver, pancreas, and spleen, and the kidneys
and supra-renal 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.
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 iu the Diaphragm, for the transmission
of the inferior vena cava ; the aortic opening, for the passage of the aorta, vena
azygos, and thoracic duct ; and the oesophageal opening, for the oesophagus and
pneumogastric 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.
Regions. For convenience of description of the viscera, as well as of reference
to the morbid condition of the contained parts, the abdomen is artificially divided
into certain regions. Thus, if two circular lines are drawn round the body, the
one parallel with the cartilages of the ninth ribs, and the other with the highest
point 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 from the cartilage
of the eighth rib on each side, down to the centre of Poupart's ligament, each of
these zones is subdivided into three parts, a middle and two lateral.
The middle region of the upper zone is called the epigastric (Im, over, and
yacrr^p, the stomach); and the two lateral regions, the right and left hypochondriac
(irto, under, and xovSpot, the cartilages). The central region of the middle zone
is the 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. The parts contained in these different
regions are the following (fig. 331): —
Right Hypochondriac.
The right lobe of the
liver and the gall-bladder,
the duodenum, hepatic
flexure of the colon, upper
part of the right kidney,
and right supra-renal cap-
sule.
Right Lumbar.
Ascending colon, lower
part of the right kidney,
and some convolutions of
the small intestines.
Right Inguinal.
The caecum, appendix
caeci, ureter, and spermatic
vessels.
Epigastric Region.
The middle and pylo-
ric end of the stomach,
left lobe of the liver and
lobus Spigelii, the hepa-
tic vessels, cceliac axis,
semilunar ganglia, pan-
creas, parts of the aorta,
vena cava, vena azygos,
and thoracic duct.
Umbilical Region.
The transverse colon,
part of the great omen-
tum and mesentery, trans-
verse part of the duode-
num, and some convolu-
tions of the jejunum and
ileum.
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 splenic end of the
stomach, the spleen and
extremity of the pancreas,
the splenic flexure of the
colon, upper half of the
left kidney, and left su-
pra-renal capsule.
Left Lumbar.
Descending colon, lower
part of left kidney, and
some convolutions of the
small intestines.
Left Inguinal.
Sigmoid flexure of the
colon, ureter, and sper-
matic vessels.
660
ORGANS OF DIGESTION.
The Peritoneum.
The Peritoneum (rtspitttvfiv, to extend around) is a serous membrane, and, like
all membranes of this class, a shut sac. In the female, hoVever, it is not
completely closed, the Fallopian tubes communicating with it by their free
extremities; and thus the serous membrane is continuous with their mucous
lining.
The peritoneum partially invests all the viscera contained in the abdominal and
pelvic cavities, forming the visceral layer of the membrane ; it is then reflected
upon the internal surface of the parietes of these cavities, forming the parietal
layer. (Fig. 332.) The free surface of the peritoneum is smooth, moist, and
covered by a thin, squamous epithelium; its attached surface is rough, being
connected to the viscera and inner surface of the parietes by means of areolar
tissue, called the sub-peritoneal areolar tissue. 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 in the middle line of the abdomen.
In order to trace the reflections of this membrane (the abdomen having been
Fig. 332.-
-The Reflections of the Peritoneum, as seen in a vertical
Section of the Abdomen.
opened), the liver should be raised and supported in that position, and the stomach
should be depressed, when a thin membranous layer is seen passing from the
transverse fissure of the liver, to the upper border of the stomach ; this is the
lesser or gastro-hepatic omentum. It consists of two thin, delicate layers of peri-
toneum, an anterior and a posterior, between which are contained the hepatic
PERITONEUM. 6«1
vessels and nerves. Of these two layers, the anterior should first be traced, and
then the posterior1.
The anterior layer descends to the lesser curvature of the stomach, and covers
its anterior surface as far as the great curvature ; it descends for some distance in
front of the small intestines, and, returning upon itself to the transverse colon,
forms the external layer of the great omentum; it then covers the under surface
of the transverse colon, and, passing to the back part of the abdominal cavity,
forms the inferior layer of the transverse mesocolon. It then descends in front of
the duodenum, the aorta, and vena cava, as far as the superior mesenteric artery,
along which it passes to invest the small intestines, and, returning to the vertebral
column, forms the mesentery; whilst, on either side, it covers the ascending and
descending colon, and is thus continuous with the peritoneum lining the walls of
the abdomen. From the root of the mesentery, it descends along the front of the
spine into the pelvis, and surrounds the upper part of the rectum, which it holds
in its position by means of a distinct fold, the mesorectum. Its course in the male
and female now differs.
In the male, it forms a fold between the rectum and bladder, the recto-vesical
fold, and ascends over the posterior surface of the latter organ as far as its summit.
In the female, it descends into the pelvis in front of the rectum, covers a small
part of the posterior wall of the vagina, and is then reflected on to the uterus, the
fundus and body of which it covers. From the sides of the uterus, it is reflected
on each side to the wall of the pelvis, forming the broad ligaments ; and from its
anterior surface it ascends upon the posterior wall of the bladder, as far as its
summit. From this point it may be traced, as in the male, ascending upon the
anterior parietes of the abdomen, to the under surface of the Diaphragm ; from
which it is reflected upon the liver, forming the upper layer of the coronary, and
the lateral and longitudinal ligaments. It then covers the upper and under sur-
faces of the liver, and at the transverse fissure becomes continuous with the
anterior layer of the lesser omentum, the point from whence its reflection was ori-
ginally traced.
The posterior layer of the lesser omentum descends to the lesser curvature of
the stomach, and covers its posterior surface as far as the great curvature; it
then descends for some distance in front of the small intestines, and, returning
upon itself to the transverse colon, forms the internal layer of the great omentum ;
it covers the upper surface of the transverse colon, and, passing backwards to the
spine, forms the upper layer of the transverse mesocolon. Ascending in front of
the pancreas and crura of the Diaphragm, it lines the back part of the under sur-
face of this muscle, from which it is reflected on to the posterior border of the liver,
forming the inferior layer of the coronary ligament. From the under surface of
the liver, it may be traced to the transverse fissure, where it is continuous with
the posterior layer of the lesser omentum, the point from whence its reflection was
originally traced.
The space included in the reflections of this layer of the peritoneum is called
the lesser cavity of the peritoneum or cavity of the great omentum. It is bounded, in
front, by the lesser omentum, the stomach, and the descending part of the great
omentum ; behind, by the ascending part of the great omentum, the transverse
colon, transverse mesocolon, and its ascending layer ; above, by the liver ; and
below, by the folding of the great omentum. This space communicates with the
general peritoneal cavity through the foramen of Winslow, which is situated be-
hind the right free border of the lesser omentum.
The foramen of Winslow is bounded in front by the lesser omentum, inclosing
the vena portas and the hepatic artery and duct ; behinft, by the inferior vena cava ;
above, by the lobus Spigelii ; below, by the hepatic artery curving forwards from
the cceliac axis.
This foramen is nothing more than a constriction of the general peritoneal
cavity at this point, caused by the hepatic and gastric arteries passing forwards from
the coeliac axis to reach their respective viscera.
662 ORGANS OF DIGESTION
The viscera thus shown to be almost entirely invested by peritoneum are the
liver, stomach, spleen, first portion of duodenum, jejunum, and ileum, transverse
colon, sigmoid flexure, upper end of rectum, uterus, and ovaries.
Those viscera partially covered by it are the descending and transverse portions
of the duodenum, the caecum, the ascending and descending colon, the middle por-
tion of the rectum, and the upper part of the vagina and posterior wall of the blad-
der. The kidneys, supra-renal capsules, and pancreas, are covered by this mem-
brane without receiving any special investment from it.
The lower end of the rectum, the neck, base, and anterior surface of the bladder,
and the lower part of the vagina, have no peritoneal investment.
Numerous folds are formed by the peritoneum, extending between the various
organs. These serve to hold them in position, and, at the same time inclose the
- -Is and nerves proceeding to each part. Some of the folds are called liga-
ments, from their serving to support the organs in position. Others, which
connect certain parts of the intestine with the abdominal wall, constitute the
mesenteries; and, lastly, those are called omenta, which proceed from one viscus to
another.
The Ligaments, formed by folds of the peritoneum, include those of the -iver,
spleen, bladder, and uterus. They are described with their respective organs.
The Omenta are the lesser or gastro-hepatic omentum, the great or gastro-colic
omentum, and the gastro- splenic omentum.
The lesser omentum (gastro-hepatic) is the duplicature which extends between
the transverse fissure of the liver, and the lesser curvature of the stomach. It is
extremely thin, and consists, as before said, of two layers of peritoneum. At the
left border, its two layers pass on to the end of the oesophagus ; but, at the right
border, where it is free, they are continuous, and form a free rounded margin,
which contains between its layers the hepatic artery, the ductus communis chole-
dochus, the portal vein, lymphatics, and hepatic plexus of nerves ; all these struc-
tures being inclosed in loose areolar tissue, called Glisson's capsule.
The great omentum {gastro-colic) 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 ; these, uniting at its lower border,
descend in front of the small intestines, as low down as the pelvis ; and the same
two ascend again as far as the transverse colon, where they separate and inclose
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.
The left border of the great omentum is continuous with the gastro-splenic omen-
tum ; 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. Its use ap-
pears to be to protect the intestines from cold, and to facilitate their movement
upon each other during their vermicular action.
The gastro-splenic omentum is the fold which connects the concave surface of
the spleen to the cul-de-sac of the stomach, being continuous by its lower border
with the great omentum. It contains the splenic vessels and the vasa brevia.
The Mesenteries are the mesentery proper, the mesocsecum, the ascending,
transverse, and descending mesocolon, the sigmoid mesocolon, and the meso-
rectum.
The mesentery (utaov, fttpov), 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. Its root, the part connected with the vertebral column, is narrow,
about six inches in length, and directed obliquely from the left side of the second
lumbar vertebra, to the right sacro-iliac symphysis. Its intestinal border is much
longer ; and here its two layers separate, so as to inclose the intestine, and form
its peritoneal coat. Its breadth, between its vertebral and intestinal border, is
about four inches. Its upp>er border is continuous with the under surface of the
STOMACH. 663
transverse mesocolon ; its lower border, with the peritoneum covering the caecum
and ascending colon. It serves to retain the small intestines in their position,
and contains between its layers the mesenteric vessels and nerves, the lacteal
vessels, and mesenteric glands.
The mesocsecum, when it exists, serves to connect the back part of the caecum
with the right iliac fossa ; more frequently, the peritoneum passes merely in front
of this portion of the large intestine.
The ascending mesocolon is the fold which connects the back part of the ascend-
ing colon with the posterior wall of the abdomen.
The descending mesocolon retains the descending colon in connection with the
posterior abdominal wall; more frequently, the peritoneum merely covers the
anterior surface and sides of these two portions of the intestine.
The transverse mesocolon is a broad fold, which connects the transverse colon
with the posterior wall of the abdomen. It is formed of the two ascending layers
of the great omentum, which, after separating to surround the transverse colon,
join behind it, and are continued backwards to the spine, where they diverge in
front of the duodenum, as already mentioned. This fold contains between its
layers the vessels which supply the transverse colon.
The sigmoid mesocolon is the fold of peritoneum which retains the sigmoid
flexure in connection with the left iliac fossa.
The mesorectum is the narrow fold which connects the upper part of the rectum
with the front of the sacrum. It contains the hemorrhoidal vessels.
The appendices epiploicas 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.
The Stomach.
The Stomach is the principal organ of digestion. It is the most dilated part
of the alimentary canal, serving for the solution and reduction of the food, which
constitutes the process of chymification. It is situated in the left hypochondriac,
the epigastric, and part of the right hypochondriac regions. Its form is irregularly
conical, curved upon itself, and presenting a rounded base, turned to the left side.
It is placed immediately behind the anterior wall of the abdomen, above the
transverse colon, below the liver and Diaphragm. Its size varies considerably in
different subjects, and also according to its state of distension. When moderately
full, its transverse diameter is about twelve inches, its vertical diameter about
four. Its weight, according to Clendenning, is about four ounces and a half. It
presents for examination two extremities, two orifices, two borders, and two
surfaces.
Its left extremity is called the greater or splenic end. It is the largest part of the
stomach, and expands for two or three inches to the left of the point of entrance
of the oesophagus. This expansion is called the great cul-de-sac or fundus. It
lies beneath the ribs, in contact with the spleen, to which it is connected by the
gastro-splenic omentum.
The lesser or pyloric end is much smaller than the preceding, and situated on a
plane anterior and inferior to it. It lies in contact with the wall of the abdomen,
the under surface of the liver, and the neck of the gall-bladder.
^ The oesophageal or cardiac orifice communicates with the oesophagus ; it is the
highest part of the stomach, and somewhat funnel-shaped in form.
The pyloric orifice communicates with the duodenum, the aperture being guarded
by a valve.
The lesser curvature extends between the oesophageal and cardiac orifices, along
the upper border of the organ, and is connected to the under surface of the liver
by the lesser omentum.
The greater curvature extends between the same points, along the lower border,
6G4
ORGANS OF DIGESTION.
and gives attachment to the great omentum. The surfaces of the organ are
limited by these two curvatures.
The anterior surface is directed upwards and forwards, and is in relation with
the Diaphragm, the under surface of the left lobe of the liver, and, in the epigas-
tric region, with the abdominal parietes.
Fig. 333. — The Mucous Membrane of the Stomach and Duodenum, with the Bile Ducts.
Cyttie
The posterior surface is directed downwards and backwards, and is in relation
with the pancreas and great vessels of the abdomen, the crura of the Diaphragm,
and the solar plexus.
The stomach is held in position by the lesser omentum, which extends from
the transverse fissure of the liver to its lesser curvature, and by a fold of peri-
toneum, which passes from the Diaphragm on to the oesophageal end of the
stomach, the gastro-phrenic ligament ; this constitutes the most fixed point of the
stomach, whilst the pyloric end and greater curvature are the most movable
parts : hence, when this organ becomes greatly distended, the greater curvature
is directed forwards, whilst the anterior and posterior surfaces are directed, the
former upwards, and the latter downwards.
Alterations in Position. There is no organ in the body the position and connections of which
present such frequent alterations as the stomach. During inspiration it is displaced downwards
by the descent of the Diaphragm, and elevated by the pressure of the abdominal muscles during
expiration. Its position to the surrounding viscera is also changed, according to the empty or
distended state of the organ, When empty, it occupies only a small part of the left hypochon-
driac region, the spleen lying behind it ; the left lobe of the liver covers it in front, and the under
surface of the heart rests upon it above, and in front, being separated from it by the left lobe of
the liver and pericardium. Hence it is, that, in gastralgia. the pain is generally referred to the
heart, and is often accompanied by palpitation and intermission of the pulse. When the
STOMACH.
G65
stomach is distended the Diaphragm is forced upwards, contracting the cavity of the chest ;
hence the dyspnoea complained of, from inspiration being impeded. The heart is also displaced
upwards ; hence the oppression in this region, and the palpitation experienced in extreme disten-
sion of the stomach. Pressure from without, as in the pernicious practice of tight lacing, pushes
the stomach down towards the pelvis. In disease, also, the position and connections of the
organ may be greatly changed, from the accumulation of fluid in the chest or abdomen, or when
the size of any of the surrounding viscera undergoes alteration.
On looking into the pyloric end of the stomach, the mucous membrane is found
projecting inwards in the form of a circular fold, the pylorus, leaving a narrow
circular aperture, about half an inch in diameter, by which the stomach commu-
nicates with the duodenum.
The pylorus is formed by a reduplication of the mucous membrane of the
stomach, containing numerous muscular fibres, which are aggregated into a
thick circular ring, the longitudinal fibres and serous membrane being continued
over the fold without assisting in its formation. The aperture is occasionally oval.
Sometimes, the circular fold is replaced by two crescentic folds, placed, one above,
and the other below, the pyloric orifice ; and, more rarely, there is only one.
Structure. The stomach consists of four coats ; a serous, a muscular, a cellular,
and a mucous coat, together with vessels and nerves.
The serous coat is derived from the peritoneum, and covers the entire surface
of the organ, excepting along the greater and lesser curvature, at the points of
attachment of the greater and lesser omenta ; here the two layers of peritoneum
leave a small triangular space, along which the nutrient vessels and nerves pass.
The muscular coat is situated immediately beneath the serous covering. It con
sists of three sets of fibres, the longitudinal, circular, and oblique (fig. 334).
Fig. 334. — The Muscular Coat of the Stomach.
The longitudinal fibres are most superficial ; they are continuous with the longi-
tudinal fibres of the oesophagus, radiating in a stellate 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.
G66
ORGANS OF DIGESTION
The circular fibres form a "uniform layer over the whole extent of the stomach,
"beneath the longitudinal fibres. At the pylorus, they are most abundant, and
are aggregated into a circular ring, which projects into the cavity, and forms, with
the fold of mucous membrane covering its surface, the pyloric valve.
The oblique fibres are limited chiefly to the cardiac end of the stomach, where
they are disposed as a thick uniform layer covering both surfaces, some passing
obliquely from left to right, others from right to left, round the cardiac orifice.
The cellular coat consists of a loose, filamentous, areolar tissue, connecting the
mucous and muscular layers. It is sometimes called the submucous coat. It
supports the bloodvessels previous to their distribution to the mucous membrane ;
hence it is sometimes called the vascular coat.
The mucous membrane of the stomach is thick; its surface smooth, soft, and
velvety. During infancy, and immediately after death, it is of a pinkish tinge ;
but in adult life, and in old age, it becomes of a pale straw or ash-gray color.
It is thin at the cardiac extremity, but thicker towards the pylorus. During the
contracted state of the organ, it is thrown into numerous plaits or rugoe, which, for
the most part, have a longitudinal direction, and are most marked towards the lesser
end of the stomach, and along the greater curvature. These folds are entirely
obliterated when the organ becomes distended.
Structure of the mucous membrane (fig. 835). When examined with a lens, the
inner surface of the mucous membrane presents a peculiar honey-comb appearance,
Fig. 335. — Minute Anatomy of Mucous Membrane of Stomach.
Mouths of Tuliuli
Orifice of Tuts
EpitheJi'cUjoarticlrS
from being covered with small shallow depressions or alveoli, of a polygonal or
hexagonal form, which vary from l-100th to l-350th of an inch in diameter, and
are separated by slightly elevated ridges. In the bottom of the alveoli are seen
the orifices of minute tubes, the gastric follicles, which are situated perpendicu-
larly side by side, in the entire substance of the mucous membrane. They are
short, and simply tubular in character towards the cardiac end ; but at the pyloric
end, they are longer, more thickly set, convoluted, and terminate in dilated saccular
extremities, or subdivide into from two to six tubular branches. The gastric
follicles are composed of a homogeneous basement membrane, lined upon its free
surface by a layer of cells, which differ in their character in different parts of the
stomach. Towards the pylorus, these tubes are lined throughout with columnar
epithelium ; they are termed the mucous glands, and are supposed to secrete the
gastric mucus. In other parts of the organ, the deep part of each tube is filled
with nuclei, and a mass of granules ; above these is a mass of nucleated cells, the
upper fourth of the tube being lined by columnar epithelium. These are called
the peptic glands, the supposed agents in the secretion of the gastric juice.
Simple follicles are found in greater or less number over the entire surface of
the mucous membrane ; they are most numerous near the pyloric end of the
stomach, and especially distinct in early life. The epithelium lining the mucous
membrane of the stomach and its alveoli is of the columnar variety.
SMALL INTESTINE. 6G7
Vessels and Nerves. The arteries supplying the stomach are, the gastric, pyloric
and right gastro-epiploic branches of the hepatic, the left gastro-epiploic and vasa
brevia from the splenic. They supply the muscular coat, ramify in the submucous
coat, and are finally distributed to the mucous membrane. The veins accompany
the arteries, and terminate in the splenic and portal veins. The lymphatics are
numerous ; they consist of a superficial and deep set, which pass through the lym-
phatic glands found along the two curvatures of the organ. The nerves are, the
terminal branches of the right and left pneumogastric, the former being distributed
upon the back, and the latter upon the front part of the organ. Branches from
the sympathetic also supply the organ.
The Small Intestine.
The Small Intestine is that part of the alimentary canal in which the chyme is
mixed with the bile, the pancreatic juice, and the secretions of the various glands
imbedded in the mucous membrane of the intestines, and where the separation of
the nutritive principles of the food, the chyle, is effected: this constitutes chyli-
fication.
The small intestine is a convoluted tube, about twenty feet in length, which
gradually diminishes in size from its commencement to its termination. It is
contained in the central and lower parts of the abdominal and pelvic cavities,
surrounded above and at the sides by the large intestine ; in relation, in front,
with the great omentum and abdominal parietes ; and connected to the spine by
a fold of peritoneum, the mesentery. The small intestine is divisible into three
portions ; the duodenum, jejunum, and ileum.
The duodenum has received its name from being about equal in length to the
breadth of twelve fingers (eight or ten inches.) It is the shortest, the widest, and
the most fixed part of the small intestine; it has no mesentery, and is only partially
covered by the peritoneum. Its course presents a remarkable curve, somewhat
like a horseshoe in form ; the convexity being directed towards the right, and
the concavity to the left, embracing the head of the pancreas. Commencing at
the pylorus, it ascends obliquely upwards and backwards to the under surface of
the liver ; it then descends in front of the right kidney, and passes nearly trans-
versely across the front of the spine, terminating in the jejunum on the left side
of the second lumbar vertebra. Hence the duodenum has been divided into three
portions : ascending, descending, and transverse.
The first or ascending portion, about two inches in length, is free, movable,
and nearly completely invested by the peritoneum. It is in relation, above and in
front, with the liver and neck of the gall-bladder ; behind, with the right border
of the lesser omentum, the hepatic artery and duct, and vena porta). This por-
tion of the intestine is usually found stained with bile, especially on its anterior
surface.
The second or descending portion, about three inches in length, is firmly fixed
by the peritoneum and pancreas. It passes from the neck of the gall-bladder
vertically downwards, in front of the right kidney, as far as the third lumbar
vertebra. It is covered by peritoneum only on its anterior surface. It is in
relation, in front, with the right arch of the colon and mesocolon ; behind, with
the front of the right kidney ; at its inner side is the head of the pancreas, and the
common choledoch duct. The common bile and pancreatic ducts perforate the
inner side of this portion of the intestine obliquely, a little below its middle.
The third or transverse portion, the longest and narrowest part of the duodenum,
passes across the front of the spine, ascending from the third to the second lumbar
vertebra, and terminating in the jejunum on the left side of this bone. In front,
it is covered by the descending layer of the transverse mesocolon, and crossed by
the superior mesenteric vessels ; behind, it rests upon the aorta, the vena cava, and
the crura of the Diaphragm ; above it is the lower border of the pancreas, the
superior mesenteric vessels passing forwards between the two.
668 ORGANS OF DIGESTION.
Vessels and Nerves. The arteries 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 terminate in the gastro-
duodenal and superior mesenteric. Its nerves are derived from the solar
plexus.
The jejunum (jejunus, empty), so called from being usually found empty after
death, includes the upper two-fifths of the rest of the small intestine. It com-
mences at the duodenum on the left side of the second lumbar vertebra, and
terminates in the ileum; its convolutions being chiefly confined to the umbilical
and left iliac regions. The jejunum is wider, its coats thicker, more vascular,
and of a deeper color than those of the ileum ; but there is no characteristic
mark to distinguish the termination of the one, or the commencement of the
other.
The ileum (ei-ktiv, to twist), so called from its numerous coils or convolutions,
includes the remaining three-fifths of the small intestine. It occupies chiefly the
umbilical, hypogastric, right iliac, and occasionally the pelvic, regions, and ter-
minates in the right iliac fossa by opening into the inner side of the commence-
ment of the large intestine. The ileum is narrower, its coats thinner and less
vascular than those of the jejunum; a given length of it weighing less than the
same length of jejunum.
Structure of the small intestine. The wall of the small intestine is composed of
four coats ; serous, muscular, cellular, and mucous.
The serous coat is derived from the peritoneum. The first or ascending por-
tion of the duodenum is almost completely surrounded by this membrane ; the
second or descending portion is covered by it only in front ; and the third or
transverse portion lies behind the descending layer of the transverse mesocolon,
by which it is covered in front. The remaining portion of the small intestine is
surrounded 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 consists of two layers of fibres, an external or longitudinal,
and an internal or circular layer. The longitudinal fibres are thinly scattered
over the surface of the intestine, and are most distinct along its free border.
The circular fibres form a thick, uniform layer ; they surround the cylinder of
the intestine in the greater part of its circumference, but do not form complete
rings. The muscular coat is thicker at the upper, than at the lower part of the
small intestine.
The cellular or submucous coat connects together the mucous and muscular
layers. It consists of a loose, filamentous, areolar tissue, which forms a nidus for
the subdivision of the nutrient vessels, previous to their distribution to the mucous
surface.
The mucous membrane is thick and highly vascular at the upper part of the
small intestine, but somewhat paler and thinner below. It presents for examina-
tion the following constituents : —
-rp vi r Simple follicles.
Epithelium. ,f> s , , i
-v/% i • , ( Duodenal glands.
Valvuke conniventes. r>, -, ) 0 v, -,& •,
Y']V (jrlands. < Solitary glands.
( Agminate or Peyer's glands.
The epithelium., covering the mucous membrane of the small intestine, is of
the columnar variety.
The valvulse conniventes (valves of Kerkring) are reduplications or foldings
of the mucous membrane and submucous tissue, containing no muscular fibres.
They extend transversely across the cylinder of the intestine for about three-
fourths or five-sixths of its circumference. The larger folds are about two inches
in length, and two-thirds 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
SMALL INTESTINE.
669
Fig. 336.— Two Villi magnified.
Artery
to appear about one or two inches beyond the pylorus. In the lower part of the
descending portion, below the point where the common choledoch and pancreatic
ducts enter the intestine, they are very large and closely approximated. In the
transverse portion of the duodenum and upper half pf the jejunum, they are large
and numerous ; and from this point, as far as 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 intestines, and afford a more extensive
surface for absorption.
The villi are minute, highly vascular
processes, projecting from the mucous mem-
brane of the small intestine throughout its
whole extent, and giving to its surface a
beautiful velvety appearance. In shape,
some are triangular and laminated, others
conical or cylindrical, with clubbed or fili-
form extremities. They are largest and
most numerous in the duodenum and jeju-
num, 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 four millions.
In structure each villus consists of a network of capillary and lacteal vessels,
with nuclear corpuscles and fat globules in their interstices, inclosed in a thin
prolongation of basement membrane covered by a single layer of columnar
epithelium, the particles of which are arranged perpendicularly to the surface. A
layer of organic muscular fibre has been described forming a thin hollow cone
round the central lacteal. It is possible that this assists in the propulsion of the
chyle along the vessel. The mode of origin of the lacteals within the villi is un-
known.
The simple follicles or crypts of Lieberkuhn 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 perpendicularly
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. Their walls are thin, consisting of a layer of basement
membrane, lined by cylindrical epithelium, and covered on their exterior by
capillary vessels. Their contents vary, even in health, and the purpose served
by their secretion is still very doubtful.
The duodenal or Brunner's glands are limited to the duodenum and com-
mencement of the jejunum. They are small, flattened, granular bodies, imbedded
in the submucous areolar tissue, and open upon the surface of the mucous mem.
brane by minute excretory ducts. They are most numerous and largest near the
pylorus. They may be compared to the elementary lobules of a salivary gland,
spread out over a broad surface, instead of being collected in a mass. In structure
they resemble the pancreas.
The solitary glands (glandulse solitarise) are found scattered throughout the
mucous membrane of the small intestine, but are most numerous in the lower
part of the ileum. They are small, round, whitish bodies, from half a line to a
line in diameter, consisting of a closed saccular cavity, having no excretory duct,
and containing an opaque white secretion. Their free surface is covered with
villi, and each gland is surrounded by openings like those of the follicles of
Lieberkuhn. Their use is not known.
CTO
ORGANS OF DIGESTION.
Fig. 337— Patch of Peyer's Glands.
From the lower part of the Ileum.
i Peyer's glands may be regarded as aggregations of solitary glands, forming
"ircular or oval patches from twenty to thirty 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, covering the portion of the tube most distant from the attachment
of the mesentery. Each patch is formed
of a group of small, round, whitish vesicles,
covered with mucous membrane. Each
vesicle consists of a moderately thick ex-
ternal capsule, having no excretory duct,
and containing an opaque white secretion.
Each is surrounded by a zone or wreath of
simple follicles, and the interspaces between
them are covered with villi. These vesicles
are usually closed ; but it has been supposed
that they open at intervals to discharge the
secretion contained within them. The mu-
cous and submucous coats of the intestine
are intimately adherent, and highly vascular,
opposite the Peyerian glands. Their use is
not known [but they are now generally sup-
posed to belong to the lymphatic system].
They are largest and most developed during
the digestive process.
The Large Intestine.
Fig. 338.— A portion of the above magnified. The Large Intestine extends from the
termination of the ileum to the anus. It
is about five feet in length ; being one-fifth
of the whole extent of the intestinal canal.
It is largest at its commencement at the
ceecum, and gradually diminishes as far as
the rectum, where there is a dilatation of
considerable size, just above the anus. It
differs from the small intestine in its greater
size, its more fixed position, and its saccu-
lated form. The large intestine, in its
course, describes an arch, which surrounds
the convolutions of the small intestine. It
commences in the right iliac fossa, in a
dilatation of considerable size, the caecum.
It ascends through the right lumbar and
hypochondriac regions, to the under surface
of the liver ; passes transversely across the
abdomen, on the confines of the epigastric
and umbilical regions, to the left hypochondriac region ; 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 (csecus, blind) is the large blind pouch or cul-de-sac extending
downwards from the commencement of the large intestine. It is the most dilated
part of this tube, measuring about two and a half inches, both in its vertical and
transverse diameters. It is situated in the right iliac fossa, immediately behind
the anterior abdominal wall, being retained in its place by the peritoneum, which
passes over its anterior surface and sides ; its posterior surface being connected by
'&rXW-;
M*m;m
jf*:/!.-."^- .CviO
•LARGE INTESTINE. 6U
loose areolar tissue with the iliac fascia. Occasionally, it is almost completely
surrounded by peritoneum, which forms a distinct fold, the mesocaecum, connecting
its back part with the iliac fossa. This fold allows the caecum considerable
freedom of movement. Attached to its lower and back part, is the appendix
vermiformis, a long, narrow, worm-shaped tube, the rudiment of the lengthened
caecum found in all the mammalia, except the ourang-outang and wombat. The
appendix varies from three to six inches in length, its average diameter being
about equal to that of a goose-quill. It is usually directed upwards and inwards
behind the caecum, coiled upon itself, and terminates in a blunt point, being retained
Fig. 339. — The Cfficnm and Colon laid open to show the
ileo-caecal Valve.
in its position by a fold of peritoneum, which sometimes forms a mesentery for it.
Its canal is small, and communicates with the caecum by an orifice which is some-
times guarded with an incomplete valve. Its coats are thick, and its mucous lining
furnished with a large number of solitary glands.
Ileo-csecal Valve. The lower end of the ileum terminates at the inner and
back part of the large intestine, opposite the junction of the caecum with the
colon. At this point, the mucous membrane forms two valvular folds, which pro-
ject into the large intestine, and are separated from each other by a narrow
elongate aperture. This is the ileo-caecal valve (valvula Bauhini). Each fold is
semilunar in form. The upper one, nearly horizontal in direction, is attached by
its convex border to the point of junction of the ileum with the colon; the lower
segment being connected at the point of junction of the ileum with the caecum.
Their concave margins are free, project into the intestine, separated from one an-
other by a narrow slit-like aperture, transversely directed. At each end of this
aperture, the two segments of the valve coalesce, and are continued, as a narrow
membranous ridge, around the canal of the intestine for a short distance, forming
the fraena or retinacula of the valve. The left end of this aperture is rounded ;
the right end is narrow and pointed.
Each segment of the valve is formed of a reduplication of the mucous mem-
brane, and of the circular muscular fibres of the intestine, the longitudinal fibres
and peritoneum being continued uninterruptedly across from one intestine to the
6T2 ORGANS OF DIGESTION.
other. When these are divided or removed, the ileum may be drawn outwards,
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 towards the ileum is covered
with villi, and presents the characteristic structure of the mucous membrane of
the small intestine ; whilst that turned towards the large intestine is destitute of
villi, and marked with the orifices of the numerous tubuli peculiar to this mem-
brane. These differences in structure continue as far as the free margin of the
valve.
When the caecum is distended, the margins of the opening are approximated, so
as to prevent any reflux into the ileum.
The colon is divided into four parts, the ascending, transverse, descending, and
the sigmoid flexure.
The ascending colon is smaller than the caecum. It passes upwards from the
right iliac fossa, to the under surface of the liver, on the right of the gall-bladder,
where it bends abruptly inwards to the left, forming the hepatic flexure. It is
retained in position 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 right kidney ; sometimes the
peritoneum almost completely invests it, and forms a distinct but narrow meso-
colon. It is in relation, in front, with the convolutions of the ileum and the
abdominal parietes; behind, it lies on the Quadratus lumborum muscle, and right
kidney.
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 downwards
beneath the lower end of the spleen, forming its splenic flexure. In its course it
describes an arch, the concavity of which is directed backwards towards the ver-
tebral column ; 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 this membrane,
the transverse mesocolon. It 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 surface, with the small intestines; by its anterior surface, with the
anterior layers of the great omentum and the abdominal parietes ; by its posterior
surface, with the transverse mesocolon.
The descending colon passes almost vertically downwards through the left hypo-
chondriac and lumbar regions to the upper part of the left iliac fossa, where it
terminates in the sigmoid flexure. 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 left crus of the Diaphragm, the left kidney, and the Quad-
ratus lumborum. It is smaller in calibre, and more deeply placed than the ascend-
ing colon.
The sigmoid flexure is the narrowest part of the colon ; it is situated in the left
iliac fossa, commencing at the termination of the descending colon, at the margin
of the crest of the ilium, and ending in the rectum, opposite the left sacro-iliac
symphysis. It curves in the first place upwards, and then descends vertically,
and to one or the other side like the letter/, hence its name; and is retained in
its place by a loose fold of peritoneum, the sigmoid mesocolon. It is in relation,
in front, with the small intestines and abdominal parietes; behind, with the iliac
fossa.
The Rectum is the terminal part of the large intestine, and extends from the
sigmoid flexure to the anus ; it varies in length from six to eight inches, and has
received its name from being somewhat less flexuous than any other part of the
intestinal canal. It commences opposite the left sacro-iliac symphysis, passes
obliquely downwards from left to right to the middle of the sacrum, forming a
gentle curve to the right side. Regaining the middle line, it descends in front of
LARGE INTESTINE. 673
tlie lower part of the sacrum and coccyx ; and, near the extremity of the latter
bone, inclines backwards to terminate at the anus, being curved both in the lateral
and anteroposterior directions. The rectum is, therefore, not straight, the upper
part being directed obliquely from the left side to the median line, the middle
portion being curved in the direction of the hollow of the sacrum and coccyx, the
lower portion presenting a short curve in the opposite direction. The rectum is
cylindrical, not sacculated like the rest of the large intestine ; it is narrower at its
upper part than the sigmoid flexure, gradually increases in size as it descends,
and immediately above the anus presents a considerable dilatation, capable of
acquiring an enormous size. The rectum is divided into three portions, upper,
middle, and lower.
The upper portion, which includes about half the length of the tube, extends
obliquely from the left sacro-iliac symphysis to the centre of the third piece of the
sacrum. It is almost completely surrounded by peritoneum, and connected to the
sacrum behind by a. duplicature of this membrane, the mesorectum. It is in
relation behind with }t]ie Pyriformis muscle, the sacral plexus of nerves, and the
branches of the internal iliac artery of the left side, which separate it from the
sacrum and sacro-iliac symphysis ; in front, it is separated, in the male, from the
posterior surface of the bladder, in the female, from the posterior surface of the
uterus and its appendages, by some convolutions of the small intestine.
The middle portion of the rectum is about three inches in length, and extends
as far as the tip of the coccyx. It is closely connected to the concavity of the
sacrum, and covered by peritoneum only on the upper part of its anterior surface.
It is in relation, in front, with the triangular portion of the base of the bladder,
the vesiculae seminales, and vasa deferentia ; more anteriorly, with the under sur-
face of the prostate. In the female, it is adherent to the posterior wall of the
vagina.
The lower portion is about an inch in length ; it curves backwards at the fore
part of the prostate gland, and terminates at the anus. This portion of the intestine
receives no peritoneal covering. It is invested by the Internal sphincter, supported
by the Levatores ani muscles, and surrounded at its termination by the External
sphincter. In the male, it is separated from the membranous portion and bulb of
the urethra by a triangular space ; and, in the female, a similar space intervener
between it and the vagina. This space forms by its base the perineum.
Structure of the large intestine. The large intestine has four coats ; serous, mus
cular, cellular, and mucous.
The serous coat is derived from the peritoneum, and invests the different portions
of the large intestine to a variable extent. The caecum is covered only on its
anterior surface and sides ; more rarely, it is almost completely invested, being
held in its position by a duplicature, the mesocaecum. The ascending and
descending colon are usually covered only in front. The transverse colon is
almost completely invested, excepting at the points corresponding to the attach-
ment of the great omentum and transverse mesocolon. The sigmoid flexure is
nearly completely surrounded, excepting at the point corresponding to the attach-
ment of the iliac mesocolon. The upper part of the rectum is almost completely
invested by the peritoneum ; the middle portion is covered only on its anterior
surface ; and the lower portion is entirely devoid of any serous covering. In the
course of the colon, and upper part of the rectum, the peritoneal coat is thrown
into a number of small pouches filled with fat, called appendices epiploicse. They
are chiefly appended to the transverse colon.
The muscular coat consists of an external longitudinal and an internal circular
layer of muscular fibres.
The longitudinal fibres are found as 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, each being about half an inch in width. These bands
commence at the attachment of the appendix vermiformis to the caecum : one, the
posterior, is placed along the attached border of the intestine ; the anterior band,
43
674
ORGANS OF DIGESTION.
the largest, becomes inferior along the arch of the colon, where it corresponds to
the attachment of the great omentum, but is in front in the ascending and
descending colon and sigmoid flexure ; the third or lateral band is found on the
inner side of the ascending and descending colon, and on the under border of the
transverse colon. These bands are nearly one-half shorter than the other parts
of the intestine, and serve to produce those sacculi characteristic of the csecum
and colon ; accordingly, when they are dissected offj the tube can be lengthened,
and its sacculated character becomes lost. In the sigmoid flexure, the longitudinal
fibres become more scattered, and upon its lower part, as well as round the rectum,
they spread out, and form a thick uniform layer.
The circular fibres form a thin layer over the caecum and colon, being especially
accumulated in the intervals between the sacculi ; in the rectum, they form a thick
layer, especially at its lower end, where they become numerous, and form the
Internal sphincter.
The cellular coat connects closely together the muscular and mucous layers.
The mucous membrane, in the caecum and colon, is pale, and of a grayish or pale
yellow color. It is quite 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. When the lower part of the rectum is
contracted, its mucous membrane is thrown into a number of folds, some of which,
near the anus, are longitudinal in direction, and are effaced by the distension of
the gut. Besides these, there are three or four permanent folds, of a semilunar
shape, described by Mr. Houston.1 They are usually three in number ; sometimes
a fourth is found, and, occasionally, only two are present. One is situated near
the commencement of the rectum, on the right side ; another extends inwards from
the left side of the tube opposite the middle of the sacrum ; the largest and most
constant one projects backwards from the fore part of the rectum, opposite the
base of the bladder. When a fourth is present, it is situated about an inch above
the anus, on the back of the rectum. These folds are about half an inch in width,
and contain some of the circular fibres of the gut. In the empty state of the
intestine they overlap each other, as Mr. Houston remarks, so effectually as to
require considerable manoeuvring to conduct a bougie or the finger along the canal
of the intestine. Their use seems to be, " to support the weight of fecal matter,
and prevent its urging towards the anus, where its presence always excites a
sensation demanding its discharge." The mucous membrane of the large intestine
presents for examination, epithelium, simple follicles, and solitary glands.
Fig. 340. — Minute Structure of Large Intestine.
Ti.Su/i
Solitary Fo/hW.
Section of Mtootur Mtoibrun*
Tuhuli TriUmj
Su-imucotu Cell. tits.
Free Surf a
The epithelium is of the columnar kind. .
The simple follicles are minute tubular prolongations of the mucous membrane,
arranged perpendicularly, side by side, over its entire surface ; they are longer,
Dub. Hosp. Repoi-ts, vol. v. p. 163.
J
THE LIVER. 6T5
more numerous, and 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.
The solitary glands in the large intestine are most abundant in the caecum and
appendix vermiformis, being irregularly scattered over the rest of the intestine ;
they are small, prominent, flask-shaped bodies, of a whitish color, perforated upon
the central part of their free surface by a minute orifice, which, in the majority,
is permanent.
The Liver.
The Liver is a glandular organ of large size, intended mainly for the secretion
of the bile, but effecting also important changes in certain constituents of the blood
in their passage through the gland. It is situated in the right hypochondriac
region, and extends across the epigastrium into the left hypochondrium. It is the
largest gland in the body, weighing from three to four pounds (from fifty to sixty
ounces avoirdupois). It measures, in its transverse diameter, from ten to twelve
inches; from six to seven in its antero-posterior ; and is about three inches thick
at the back part of the right lobe, which is the thickest part.
Its upper surface is convex, directed upwards and forwards, smooth, covered
by peritoneum, and is in relation with the under surface of the Diaphragm ; and
below, to a small extent, with the abdominal parietes. This surface is divided
into two unequal lobes, the right and left, by a fold of peritoneum, the suspensory
or broad ligament.
Its under surface is concave, directed downwards and backwards, and in rela*
tion with the stomach and duodenum, the hepatic flexure of the colon, and the
right kidney and supra-renal capsule. This surface is divided by a longitudinal
fissure, into a right and left lobe.
The posterior border is rounded and broad, and connected to the Diaphragm by
the coronary ligament; it is in relation with the aorta, the vena cava, and the
crura of the Diaphragm.
The anterior border is thin and sharp, and marked, opposite the attachment of
the broad ligament, by a deep notch. In adult males, this border usually corre-
sponds with the margin of.'the ribs ; but in women and children, it projects usually
below this point.
The right extremity of the liver is thick and rounded ; whilst the left is thin and
flattened.
Changes of Position. The student should make himself acquainted with the different circum-
stances under which the liver changes its position, as they are of importance as a guide in deter-
mining the existence of enlargement, or other disease of that organ.
Its position varies according to the posture of the body; in the upright and sitting postures,
its lower border may be felt beneath the edges of the ribs ; in the recumbent posture, it usually
recedes beneath the ribs.
Its position varies with the ascent or descent of the Diaphragm. In a deep inspiration, the
liver descends below the ribs ; in expiration, it is raised to its ordinary level. Again, in emphy-
sema, where the lungs are distended, and the Diaphragm descends very low, the liver is pushed
down ; but in some other diseases, 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, dis-
places 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 pressure of the ribs.
Its position varies greatly, according to the greater or less distension of the stomach and
intestines. When the intestines are empty, the liver descends in the abdomen ; but when they
are distended, it is pushed upwards. Its relations with surrounding organs may also be changed
by the growth of tumors, or from collections of fluid in the thoracic or abdominal cavities.
Ligamexts. The ligaments of the liver (fig. 341) are five in number : four
are formed of folds of peritoneum ; the fifth, the ligamentum teres, is a round,
fibrous cord, resulting from the obliteration of the umbilical vein. The ligaments
are the longitudinal, two lateral, coronary, and round.
676 ORGANS OF DIGESTION.
The longitudinal ligament (broad, falciform, or suspensory ligament) is a broad
and thin antcro-posterior peritoneal fold, falciform in shape, its base being directed
forwards, its apex backwards. It is attached by one margin to the under surface
of the Diaphragm, and the posterior surface of the sheath of the right Rectus
muscle as low down as the umbilicus ; by its hepatic margin, it extends from the
notch on the anterior margin of the liver, as far back as its posterior border. It
consists of two layers of peritoneum closely united together. Its anterior free
edge contains between its layers the round ligament.
The lateral ligaments, two in number, right and left, are triangular in shape.
They are formed of two layers of peritoneum united, and extend from the sides
of the Diaphragm to the adjacent margins of the posterior border of the liver.
The left is the longer of the two, and lies in front of the oesophageal opening in
the Diaphragm ; the right lies in front of the inferior vena cava.
The coronary ligament connects the posterior border of the liver to the Diaphragm.
It is formed by the reflection of the peritoneum from the Diaphragm on to the
upper and lower margins of the posterior border of the organ. The coronary
Fig. 341. — The Liver. Upper Surface.
ligament consists of two layers, which are continuous on each side with the lateral
ligaments, and, in front, with the longitudinal ligament. Between the layers, a
large oval interspace is left uncovered by peritoneum, and connected to the
Diaphragm by firm areolar tissue. This space is subdivided, near its left extremity,
into two parts by a deep notch (sometimes a canal), which lodges the inferior
vena cava, and into which open the hepatic veins.
The round ligament is a fibrous cord, resulting from the obliteration of the
umbilical vein. It ascends from the umbilicus in the anterior free margin of the
longitudinal ligament, to the notch in the anterior border of the liver, from which
it may be traced along the longitudinal fissure on the under surface of the liver,
as far back as the inferior vena cava.
Fissures. Five fissures are seen upon the under surface of the liver, which
serve to divide it into five lobes. They are the longitudinal fissure, the fissure of
the ductus venosus, the transverse fissure, the fissure for the gall-bladder, and the
fissure for the vena cava.
The longitudinal fissure is a deep groove, which extends from the notch on the
anterior margin of the liver, to the posterior border of the organ. It separates
the right and left lobes ; the transverse fissure joins it, at right angles, about
THE LIVER.
677
one-third from its posterior extremity, and divides it into two parts. The anterior
half is called the umbilical fissure; it is deeper than the posterior part, and lodges
the umbilical vein in the foetus, or its fibrous cord (the round ligament) in the
adult. This fissure is often partially bridged over by a prolongation of the hepatic
substance, the p>ons hepatis.
The fissure of the ductus venosus is the back part of the longitudinal fissure ;
it is shorter and shallower than the anterior portion. It lodges in the foetus the
ductus venosus, and in the adult a slender fibrous cord, the obliterated remains of
that vessel.
Via. 342.— The Liver. Under Surface.
The transverse or portal fissure is a short but deep fissure, about two inches
in length, extending transversely across the under surface of the right lobe, nearer
to its posterior than its anterior border. It joins, nearly at right angles, with the
longitudinal fissure. By the older anatomists, this fissure was considered the
gateway (porta) of the liver ; hence the large vein which enters at this point was
called the portal vein. Besides this vein, the fissure transmits the hepatic artery
and nerves, and the hepatic duct and lymphatics. At their entrance into the
fissure, the hepatic duct lies in front to the right, the portal vein behind, and the
hepatic artery between the other two to the left.
The fissure for the gall-bladder (fossa cystidis fellese) 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 occa-
sionally notched for its reception, to near the right extremity of the transverse
fissure.
The fissure for the vena cava is a short deep fissure, occasionally a complete
canal, which extends obliquely upwards from a little behind the right extremity
of the transverse fissure, to the posterior border of the organ, where it joins the
fissure for the ductus venosus. On slitting open the inferior vena cava which
is contained in it, a deep fossa is seen, at the bottom of which the hepatic veins
communicate with this vessel. This fissure is separated from the transverse
fissure by the lobus caudatus ; and from the longitudinal fissure by the lobus Spi-
gelii.
Lobes. The lobes of the liver, like the ligaments and fissures, are also five in
number ; the right lobe, the left lobe, the lobus quadratus, the lobus Spigelii, and
the lobus caudatus.
The right lobe is much larger than the left ; the proportion between them being
678 ORGANS OF DIGESTION.
.is six to one. It occupies the right hypochondrium, and is separated from the left
lobe, on its upper surface, by the longitudinal ligament; on its under surface, by
the longitudinal fissure ; and in front, by a deep notch. It is of a quadrilateral
form, its under surface being marked by three fissures, the transverse fissure,
the fissure for the gall-bladder, and the fissure for the inferior vena cava ; and by
two shallow impressions, one in front (impressio colica), for the hepatic flexure of
the colon, and one behind {impressio renalis), for the right kidney and supra-renal
capsule.
The left lobe is smaller and more flattened than the right. It is situated in the
epigastric and left hypochondriac regions, sometimes extending as far as the upper
border of the spleen. Its upper surface is convex ; its under concave surface rests
upon the front of the stomach ; and its posterior border is in relation with the car-
diac orifice of the stomach.
The lobus quadratus or square lobe is situated on the under surface of the right
lobe, bounded in front by the free margin of the liver ; behind, by the transverse
fissure ; on the right, by the fissure for the gall-bladder ; and, on the left, by the
umbilical fissure.
The lobus Sjrigelii projects from the back part of the under surface of the
right lobe. It is bounded, in front, by the transverse fissure ; on the right, by
the fissure for the vena cava ; and on the left, by the fissure for the ductus
venosus.
The lobus caudatus or tailed lobe is a small elevation of the hepatic substance,
extending obliquely outwards, from the base of the lobus Spigelii, to the under
surface of the right lobe. It separates the right extremity of the transverse fissure
from the commencement of the fissure for the inferior vena cava.
Vessels. The vessels connected with the liver are also five in number ; they
are the hepatic artery, the portal vein, the hepatic vein, the hepatic duct, and lym-
phatics.
The hepatic artery, portal vein, and hepatic duct, accompanied by numerous
lymphatic vessels and nerves, ascend to the transverse fissure, between the layers
of the gastro-hepatic omentum ; the hepatic duct lying to the right, the hepatic
artery to the left, and the portal vein behind the other two. They are enveloped
in a loose areolar tissue, the capsule of Glisson, which accompanies the vessels
in their course through the portal canals, which are hollowed out of the interior
of the organ.
The hepatic veins convey the blood from the liver. They commence at the cir-
cumference of the organ, and proceed towards the deep fossa in its posterior border,
where they terminate by two large, and several smaller branches, in the inferior
vena cava.
The hepatic veins have no cellular investment, consequently their parietes are
adherent to the walls of the canals through which they run ; so that, on a section
of the organ, these veins remain widely open and solitary, and may be easily dis-
tinguished from the branches of the portal vein, which are more or less collapsed,
and always accompanied by an artery and duct.
The lymphatics are large and numerous, consisting of a deep and superficial set.
They have been already described.
Nerves. The nerves of the liver are derived from the hepatic plexus of the
sympathetic, from the pneumogastric nerves, especially the left, and from the
right phrenic.
Structure. The substance of the liver is composed of lobules, held together by
an extremely fine areolar tissue, of the ramifications of the portal vein, hepatic
duct, hepatic artery^ hepatic veins, lymphatics, and nerves; the whole being
invested by a fibrous and a serous coat.
The serous coat is derived from the peritoneum, and invests the entire surface of
the organ, excepting at the point corresponding to the attachment of its various
ligaments, and at the bottom of the different fissures, where it is deficient. It is
intimately adherent to the fibrous coat.
STRUCTURE OF THE LIVER.
679
The 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 continuous with the capsule of
Glisson ; and, on the surface of the organ, with the areolar tissue separating the
lobules.
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. When divided longitudinally,
they have a foliated margin, and, if trans-
versely, a polygonal outline. The bases
of the lobules are clustered round the
smallest branches (sublobular) of the
hepatic veins, to which each is connected
by means of a small branch, which issues
from the centre of the lobule (intra-
lobular). The remaining part of the sur-
face of each lob ale is imperfectly isolated
from the surrounding lobules, by a thin
stratum of areolar tissue, and by the
smaller vessels and ducts.
If one of the hepatic 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 mi-
nute aperture, the mouth of a sublobular
vein.
Each lobule is composed of a mass of
cells ; of a plexus of biliary ducts ; of a
venous plexus, formed by branches of
the portal vein ; of a branch of an he-
patic vein (intralobular); of minute
arteries ; and probably, of nerves and
lymphatics.
The hepatic cells form the chief mass
of the substance of a lobule, and lie in
the interspaces of the capillary plexus,
being probably contained in a tubular
network, which forms the origin of the
biliary ducts. The smallest branches of
the vena portaa pass between the lobules,
around which they form a plexus, the
interlobular. Branches from this plexus
enter the lobules, and form a network in
their circumference. The radicles of the
portal vein communicate with those of
the hepatic vein, which occupy the centre
of the lobule ; and the latter converge to
form the intralobular vein, which issues
from the base of the lobule, and joins the
hepatic vein. The portal vein carries
the blood to the liver, from which the
bile is secreted; the hepatic vein carries
H. Longitudinal section of an hepatic vein ; a, por-
tion of the canal, from which the vein has been
removed ; b, orifices of nltimate twigs of the vein
(sub-lobular), situated in the centre of the lobules.
After Kieruan.
Longitudinal section of a small portal vein and
canal, after Kiernan. a. Portions of the caual
from which the vein has been removed ;• b, side
of the portal vein in contact with the canal-,
e, the side of the vein which is separated from
the canal by the hepatic artery and d'uct, with
areolar tissue (Glisson's capsule); d, lateral sur-
face of the portal vein, through which are seen
the outlines of the lobules and the openings of
the interlobular veins ; /, vaginal voins of Kie*
nan ; g, hepatic artery ; A,, hepatic. duct
680
ORGANS OF DIGESTION.
from the liver the superfluous blood ; and the bile duct carries from the liver the
bile secreted by the hepatic cells.
The hepatic cells form the chief mass of each lobule : they are of a more or
less spheroidal form ; but may be rounded, flattened, or many-sided, from mutual
compression. They vary in size from the TTsW^h to the ^'^th of an inch in
diameter, and contain a distinct nucleus in the interior, or even sometimes two.
In the nucleus is a highly refracting nucleolus, with granules. The cell-contents
are viscid, and contain yellow particles, the coloring matter of the bile, *ind oil
globules. The cells adhere together by their surfaces, so as to form rows, which
radiate from the centre towards the circumference of the lobule. These cells are
probably the chief agents in the secretion of the bile.
Biliary dwts. The precise mode of origin of the biliary ducts is uncertain.
Mr. Kiernan's original view, confirmed as it is by the researches of Dr. Beale,
shows that the ducts commence within the lobules, in a plexiform network
(lobular biliary plexus), in which the hepatic cells lie. According to Henle,
Handheld Jones, and Kolliker, the cells are packed in the interspaces of the
capillary plexus, and, by means of temporary communications, transmit their
contents into the minute bile ducts which originate in the spaces behveen the
lobules, never entering within them. The ducts form a plexus (interlobular)
between the lobules ; and the interlobular branches unite into vaginal branches,
which lie in the portal canals, with branches of the portal vein and hepatic duct.
The ducts finally join into two large trunks which leave the liver at the trans-
verse fissure, and these joining form the hepatic duct.
The Portal vein, on entering the liver at the transverse fissure, divides into
primary branches, which are contained in the portal canals, together with branches
of the hepatic artery and duct, and the nerves and lymphatics. In the larger
portal canals, the vessels are separated from the parietes, and joined to each other
by a loose cellular web, the capsule of Glisson. The veins, as they lie in the portal
canals, give off vaginal branches, which form a plexus (vaginal plexus) in
Glisson's capsule. From this plexus, and from the portal vein itself, small
branches are given off, which pass between the lobules (interlobular veins) ; these
cover the entire surface of the lobules, excepting their bases. The lobular
branches are derived from the interlobular veins ; they penetrate into the lobule,
and form a capillary plexus within them. From this plexus the intralobular vein
arises.
The Hepatic artery appears destined chiefly for the nutrition of the coats of the
large vessels, the ducts, and the investing membranes of the liver. It enters
the liver at the transverse fissure, with
the portal vein and hepatic duct, and
ramifies with these vessels through the
portal canals. It gives off vaginal branches,
which ramify in the capsule of Glisson ;
and other branches, which are distributed
to the coats of the vena portse and hepatic
duct. From the vaginal plexus, inter-
lobular branches are given off, which
ramify through the interlobular fissures,
a few branches being distributed to the
lobules. Kiernan supposes, that the
branches of the hepatic artery terminate
in a capillary plexus, which communicates
with the branches of the vena portse.
The Hepatic veins commence in the
interior of each lobule by a plexus, the
branches of which converge to form the
intralobular vein.
The intralobular vein passes through the centre of the lobule, and leaves it at
its base to terminate in a sublobular vein.
Fig. 345
7-y
A transverse section of a small portal canal and its
vessels, after Kiernan. 1. Portal vein; 2, intrr-
lobular branches ; 3, branches of the vein, termed,
by Mr. Kiernan, vaginal, also giving off inter-
lobular branches ; 4, hepatic duct ; 6, hepatic
artery.
GALL-BLADDER. 681
The sublobular veins unite with neighboring branches to form larger veins ; and
these join to form the large hepatic trunks, which terminate in the vena cava.
Gall-bladder.
The Gall-bladder is the reservoir for the bile ; it is a conical or pear-shaped
membranous sac, lodged in a fossa on the under surface of the right lobe of the
liver, and extending from near the right extremity of the transverse fissure to the
anterior free margin 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, the broad extremity, is directed down-
wards, forwards, and to the right, and occasionally projects from the anterior border
of the liver : the body and neck are directed upwards and backwards to the left.
The gall-bladder is held in its position by the peritoneum, which, in the majority
of cases, passes over its under surface, but it occasionally invests it, and is con-
nected 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 first portion of the duodenum, occasionally the pyloric end of the
stomach, and the hepatic flexure of the colon. The fundus is completely invested
by peritoneum; it is in relation, in front, with the abdominal parietes, immediately
below the tenth costal cartilage ; behind, with the transverse arch of the colon.
The neck is narrow, and curves upon itself like the Italic letter/; at its point of
connection with the body and with the cystic duct, it presents a well-marked
constriction.
When the gall-bladder is distended with bile or 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 fistulse, through which biliary calculi
may pass out, and of the passage of calculi from the gall-bladder into the stomach, duodenum,
or colon, which occasionally happens.
Structure. The gall-bladder consists of three coats ; serous, fibrous and muscular,
and mucous.
The external or serous coat is derived from the peritoneum; it completely invests
the fundus, but covers the body and neck only on their under surface.
The middle or fibrous coat is a thin but strong fibrous layer, which forms the
framework of the sac, consisting of dense fibres which interlace in all directions.
Plain muscular fibres are also found in this coat, disposed chiefly in a longitudinal
direction, a few running transversely.
The internal or mucous coat is loosely connected with the fibrous layer. It is
generally tinged with a yellowish-brown color, and is everywhere elevated into
minute rugee, 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 inwards so as to form a
large valvular fold.
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
communis choledochus with the mucous membrane of the alimentary canal.
The Biliary Ducts are the hepatic, the cystic, and the ductus communis
choledochus. ^
The hepatic duct is formed of two trunks of nearly equal size, which issue
from the liver at the transverse fissure, one from the right and one from the left
lobe ; these unite, and pass downwards and to the right for about an inch and a
half to join at an acute angle with the cystic duct, to form the common choledoch
duct.
•
682 ORGANS OF DIGESTION.
The cystic duct, the smallest of the three biliary ducts, is about an inch in length.
It passes obliquely downwards and to the left from the neck of the gall-bladder,
and joins the hepatic duct to form the common duct. It lies in the gastro-hepatic
omentum in front of the vena cava, the cystic artery lying to its left side. The
mucous membrane lining its interior is thrown into a series of crescentic folds,
from five to twelve in number, which project into the duct in regular succession,
and are directed obliquely round the tube, presenting much the appearance of a
continuous spiral valve. They exist only in the human subject. When the duct
has been distended, the interspaces between the folds are dilated, so as to give to
its exterior a sacculated appearance.
The ductus communis 'choledochus, the largest of the three, is the common excre-
tory duct of the liver and gall-bladder. It is about three inches in length, of the
diameter of a goose-quill, and formed by the junction of the cystic and hepatic
ducts. It descends along the right border of the lesser omentum, behind the
first portion of the duodenum, in front of the vena portae, and to the right of the
hepatic artery; it then passes between the pancreas and descending portion of the
duodenum, and running for a short distance along the right side of the pancreatic
duct, near its termination, passes with it obliquely between the mucous and
muscular coats, the two opening by a common orifice upon the summit of a
papilla, situated at the inner side of the descending portion of the duodenum, a
little below its middle.
Structure. The coats of the biliary ducts are composed of an external or fibrous,
and an internal or mucous layer. The fibrous coat is composed of a strong areolar
fibrous tissue. The mucous coat is continuous with the lining membrane of the
hepatic ducts and gall-bladder, and also with that of the duodenum. It is provided
with numerous glands, the orifices of which are scattered irregularly in the larger
ducts, but in the smaller hepatic ducts are disposed in two longitudinal rows, one
on each side of the vessel. These glands are of two kinds. Some are ramified
tubes, which occasionally anastomose, and from the sides of which saccular dila-
tations are given off; others are small clustered cellular glands, which open either
separately into the hepatic duct, or into the ducts of the tubular glands.
The Pancreas.
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. 2. By
raising the stomach, the arch of the colon, and great omentum upwards, and then dividing the
inferior layer of the transverse mesocolon. 3. By dividing the two layers of peritoneum, which
descend from the great curvature of the stomach to form the great omentum ; turning this organ
upwards, and then cutting through the ascending layer of the transverse mesocolon.
The Pancreas (*w-«pia$, all flesh) is a conglomerate gland, analogous in its
structure to the salivary glands. In shape, it is transversely oblong, flattened
from before backwards, and bears some slight resemblance to a hammer, its right
extremity being broad, and presenting a sort of angular bend from above down-
wards, called the head; its left extremity gradually tapers to form the tail, the
intermediate portion being called the body. It is situated transversely across the
posterior wall of the abdomen, at the back of the epigastric and both hypochon-
driac regions. Its length varies from six to eight inches, its breadth is an inch
and a half, and its thickness from half an inch to an inch, being thicker at its
right extremity and along its upper border. Its weight varies from two to three
and a half ounces, but it may reach six ounces.
The right extremity or head of the pancreas (fig. 346) is curved upon itself
from above downwards, and is embraced by the concavity of the duodenum. The
common bile duct descends behind, between the duodenum and pancreas ; and the
pancreatico-duodenal artery descends in front between the same parts. Upon its
posterior part is a lobular fold of the gland, which passes transversely to the left,
behind the superior mesenteric vessels, forming the back part of the canal, in
PANCREAS. 683
which they are contained. It is sometimes detached from the rest of the gland,
and is called the lesser pancreas.
The lesser end or tail of the pancreas is narrow; it extends to the left as far
as the spleen, and is placed over the left kidney and supra-renal capsule.
The body of the pancreas is convex in front, and covered by the ascending
layer of the transverse mesocolon and the posterior surface of the stomach.
The posterior surface is concave, and has the following structures interposed
between it and the first lumbar vertebra: — the superior mesenteric artery and vein,
and commencement of the vena portee, the vena cava, the aorta, the left kidney,
supra-renal capsule, and corresponding renal vessels.
The upper border is thick, and has resting upon it, near its centre, the cceliac
axis; the splenic artery and vein are lodged in a deep groove or canal in this
Fig. 346. — The Pancreas and its Relations.
border, and, to the right, the first part of the duodenum and the hepatic artery are
in relation with it.
The lower border, thinner than the upper, is separated from the transverse
portion of the duodenum by the superior mesenteric artery and vein ; to the left
of these the inferior mesenteric vein ascends behind the pancreas to join the splenic
vein.
The pancreatic duct, called also the canal of Wirsung from its discoverer, extends
transversely from left to right through the substance of the pancreas, nearer to its
lower than its upper border, and lying nearer its anterior than its posterior sur-
face. In order to expose it, the superficial portion of the gland must be removed.
It commences by an orifice common to it and the ductus communis choledochus
upon the summit of an elevated papilla, situated at the inner side of the descending
portion of the duodenum, a little below its middle. Passing very obliquely
through the mucous and muscular coats, it separates itself from the common
choledoch duct, and, ascending slightly, runs from right to left through the middle
of the gland, giving off numerous branches, which pass to be distributed to its
lobules.
Sometimes the pancreatic and common choledoch ducts open separately into the
684 ORGANS OF DIGESTION.
duodenum. The excretory duct of the lesser pancreas is called the ductus pan-
creaticus minor ; it opens into the main duct near the duodenum, and sometimes
separately into that intestine, at a distance of an inch or more from the termination
of the principal duct.
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 thin, smooth, and furnished, near its termination, with a few
scattered follicles.
Sometimes the pancreatic duct is double, up to its point of entrance into the
duodenum.
The Structure of the pancreas closely resembles that of the salivary glands ; but it
is looser and softer in its texture. The fluid secreted by it is almost identical with
saliva.
Vessels and Nerves. The arteries of the pancreas are derived from the splenic,
the pancreatico-duodenal branch of the hepatic, and the superior mesenteric.
Its veins open into the splenic and superior mesenteric veins. Its lymphatics
terminate in the lumbar glands. The nerves are filaments from the splenic
plexus.
The Spleen.
The Spleen is usually classified together with the thyroid, supra-renal and
thymus glands, as one of the ductless glands, from its possessing no excretory duct.
It is of an oblong flattened form, soft, of very brittle consistence, highly vascular,
of a dark bluish-red color, and situated in the left hypochondriac region, em-
bracing the cardiac end of the stomach. It is invested by peritoneum, and
connected with the stomach by the gastro-splenic omentum.
Relations. Its external surface is convex, smooth, and in relation with the
under surface of the Diaphragm, which separates it from the ninth, tenth, and
eleventh ribs of the left side.
The internal surface is slightly concave, and divided by a vertical fissure, the
hilus, into an anterior or larger, and a posterior or smaller portion. The hilus is
pierced by several large, irregular apertures, for the entrance and exit of vessels
and nerves. At the margins of the hilus, the two layers of peritoneum are
reflected from the surface of the spleen on to the cardiac end of the stomach,
forming the gastro-splenic omentum, which contains between its layers the splenic
vessels and nerves, and the vasa brevia. The internal surface is in relation, in
front, with the great end of the stomach ; below, with the tail of the pancreas ;
and behind, with the left crus of the Diaphragm and corresponding supra-renal
capsule. '
Its upper end, thick and rounded, is in relation with the Diaphragm, to which
it is connected by a fold of peritoneum, the suspensory ligament.
Its lower end is pointed ; it is in relation with the left extremity of the trans-
verse arch of the colon.
Its anterior margin is free, rounded, and often notched, especially below.
Its posterior margin is rounded, and lies in relation with the left kidney, to
which it is connected by loose areolar tissue.
The spleen is held in its position by two folds of peritoneum ; one, the gastro-
splenic omentum, connects it with the stomach, and the other, the susjiensory
ligament, with the under surface of the Diaphragm.
The size and weight of the spleen are liable to very extreme variations at
different 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
about five inches in length, three or four inches in breadth, and an inch or an inch
and a half in thickness, and weighs about seven ounces. At birth, its weight, in
proportion to the entire body, is almost equal to what is observed in the adult,
being as 1 to 350 ; whilst 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 pro-
SPLEEN. ' 6S5
portion 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 18 to 20 pounds.
Structure. The spleen is invested by two coats ; an external serous, and an
internal fibrous elastic coat.
The external or serous coat is derived from the peritoneum; it is thin, smooth,
and in the human subject intimately adherent to the fibrous elastic coat. It
invests almost the entire organ, being reflected from it at the hilus, on to the
great end of the stomach, and at the upper end of the organ on to the Dia-
phragm.
The fibrous elastic coat forms the framework of the spleen. It invests the
exterior of the organ, and at the hilus is reflected inwards upon the vessels in the
form of vaginae or sheaths. From these sheaths, as well as from the inner surface
of the fibro-elastic coat, numerous small fibrous trabeculve or bands (fig. 347) are
given off in all directions ; these, uniting, constitute the areolar framework of the
spleen. The proper coat, the sheaths of the vessels, and the trabecule, consist of
Fig. 347. — Transverse Section of the Spleen, showing the Trabecular Tissue
and the Splenic Vein and its Branches.
a dense mesh of white and yellow elastic fibrous tissues, the latter considerably
predominating. It is owing to the presence of this tissue, that the spleen pos-
sesses a considerable amount of elasticity, admirably adapted for the very con-
siderable variations in size that it presents under certain circumstances. In some
of the mammalia, in addition to the usual constituents of this tunic, there are found
numerous pale, flattened, spindle-shaped, nucleated fibres, like unstriped muscular
fibres. It is probably owing to this structure, that the spleen possesses, when acted
upon by the galvanic current, faint traces of contractility.
The proper substance of the spleen occupies the interspaces of the areolar frame-
work of the organ ; it is a soft, pulpy mass, of a dark reddish-brown color, consist-
ing of colorless and colored elements.
The colorless elements consist of granular matter; nuclei, about the size of
the red blood-disks, homogeneous or granular in structure, and nucleated vesicles
in small numbers. These elements form, probably, one-half or two-thirds of the
686 ORGANS OF DIGESTION.
whole substance of the pulp, filling up the interspaces formed by the partitions of
the spleen, and lying in close contact with the walls of the capillary vessels, so as
to be readily acted upon by the nutrient fluid which permeates them. These
elements form a large part of the entire bulk of the spleen in well-nourished ani-
mals ; whilst they diminish in number, and occasionally are wanting, in starved
animals. The application of chemical tests shows that they are essentially a pro-
tein compound.
The colored elements of the pulp consist of red blood-globules and of colored
corpuscles, either free, or included in cells. Sometimes, unchanged blood-disks
are seen included in a cell ; but more frequently the included blood-disks are
altered both in form and color. Besides these, numerous deep-red, or reddish-
yellow, or black corpuscles and crystals, either single or aggregated in masses, are
seen diffused throughout the pulp-substance ; these, in chemical composition, are
closely allied to the hasmatin of the blood.
Malpighian Corpuscles. — On examining the cut surface of a healthy spleen, a
number of small semi-opaque bodies, of gelatinous consistence, are seen dissemi-
nated throughout its substance ; these are the splenic or Malpighian corpuscles
Fig. 348. — The Malpighian Corpuscles, and their Relation with the Splenic Artery
and its Branches.
(fig. 348). They may be seen at all periods of life ; but they are more distinct
inearly life, than in adult life or old age ; and they are much smaller in man, than
in most mammalia. They are of a spherical or ovoid form, vary considerably
in size and number, and are of a semi-opaque whitish color. They are appended
to the sheaths of the smaller arteries and their branches, presenting a resemblance
to the buds of the moss rose. Each consists of a membranous capsule, composed
of fine pale fibres, which interlace in all directions. In man, the capsule is homo-
geneous in structure, and formed by a prolongation from the sheaths of the small
arteries to which the corpuscles are attached. The bloodvessels ramifying on
the surface of the corpuscles consist of the larger ramifications of the arteries to
which the sacculus is connected ; and also of a delicate capillary plexus, similar
to that surrounding the vesicles of other glands. These vesicles have also a
close relation with the veins (fig. 349). These vessels, which are of considerable
STRUCTURE OF THE SPLEEN.
G87
size even at their origin, commence on the surface of each vesicle throughout the
whole of its circumference, forming a dense mesh of veins, in which each of these
Fig. 349.— One of the Splenic Corpuscles, showing its Relations
with the Bloodvessels.
bodies is inclosed. It is probable, that from the blood contained in the capillary
network, the material is separated which is occasionally stored up in their cavity ;
the veins being so placed as to carry off) under certain conditions, those contents
Fig. 350. — Transverse Section of the Human Spleen, showing the Distribution
of the Splenic Artery and its Branches.
that are again to be discharged into the circulation. Each capsule contains a soft,
white, semi-fluid substance, consisting of granular matter, nuclei similar to those
found in the pulp, and a few nucleated cells, the composition of which is apparently
638 ORGANS OF DIGESTION.
albuminous. These bodies are very large after digestion is completed, in well-fed
animals, and especially in those fed upon albuminous diet. In starved animals,
they disappear altogether.
The splenic artery is remarkable for its large size, in proportion to the size
of the organ ; and also for its tortuous course. It divides into from four to six
branches, which enter the hilus of the organ, and ramify throughout its substance
(fig. 350), receiving sheaths from an involution of the external fibrous tunic,
the same sheaths also investing the nerves and veins. Each branch runs in the
transverse axis of the organ, from within outwards, 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 terminate in the proper
substance of the spleen, in small tufts or pencils of capillary vessels, which lie in
direct contact with the pulp. Each of the larger branches of the arteries supplies
chiefly that region of the organ in which the branch ramifies, having no anasto-
mosis with the majority of the other branches.
The capillaries, supported by the minute trabecular, traverse the pulp in all
directions, and terminate either directly in the veins, or open into lacunar spaces,
from which the veins originate.
The veins are of large size, as compared with the size of the organ, and their
distribution is limited, like that of the arteries, to the supply of a particular part
of the gland ; they are much larger and more numerous than the arteries. They
originate, 1st, as continuations of the capillaries of the arteries ; 2dly, by inter-
cellular spaces communicating with each other ; 3dly, by distinct carcal pouches.
By their junction they form from four to six branches, which emerge from the
hilus ; and these, uniting, form the splenic vein, the largest branch of the vena
porta).
The lymphatics form a deep and superficial set ; they pass through the lym-
phatic glands at the hilus, and terminate in the thoracic duct.
The nerves are derived from branches of the right and left semilunar ganglia,
and right pneumogastric nerve.
The Thorax.
The Thorax is a conical, osseous framework, connected with the middle region
of the spine. It is narrow above, broad below, flattened before and behind, and
somewhat cordiform on a transverse section.
Boundaries. It is bounded in front by the sternum, the six upper costal
cartilages, the ribs, and intercostal muscles ; at the sides, by the ribs and inter-
costal muscles ; and behind, by the same structures and the dorsal portion of the
vertebral column.
The superior opening of the thorax is bounded on each side by the first rib ;
in front, by the upper border of the sternum ; and behind, by the first dorsal
vertebra. It is broader from side to side, than from before backwards ; and its
direction is backwards and upwards.
The lower opening or base is bounded in front by the ensiform cartilage;
behind, by the last dorsal vertebra ; and on each side by the last rib, the Dia-
phragm filling in the intervening space. Its direction is obliquely downwards
and backwards, so that the cavity of the thorax is much deeper on the posterior
wall, than on the anterior. It is wider transversely than from before backwards,
and its general direction is convex towards the chest ; but it is more flattened at
the centre than at the sides, and rises higher on the right than on the left side,
corresponding in the dead body to the upper border of the fifth costal cartilage,
on the right side ; and to the corresponding part of the sixth cartilage on the left
side.
The parts which pass through the upper opening of the thorax are, from before
backwards, the Sterno-hyoid and Sterno-thyroid muscles, the remains of the
thymus gland, the trachea, oesophagus, thoracic duct, and the Longi colli muscles ;
on the sides, the arteria innominata, the left carotid and left subclavian arteries,
the internal mammary and superior intercostal arteries, the right and left vena?
innominata?, and the inferior thyroid veins, the pneumogastric, sympathetic,
phrenic, and cardiac nerves, 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 viscera contained in the thorax are, the great central organ of circulation,
the heart, inclosed in its membranous bag, the pericardium ; and the organs of
respiration, the lungs, invested by the pleura?.
The Pericardium.
The Pericardium is a conical membranous sac, in which the heart and the
commencement of the great vessels are contained. It is placed behind the sternum,
and the cartilages of the fourth, fifth, sixth, and seventh ribs of the left side, in
the interval between the pleurae.
Its apex is directed upwards, 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 of the Diaphragm, extending a little farther to the left than the right side.
In front, it is separated from the sternum by the remains of the thymus gland
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 pleura? ; the phrenic vessels
and nerve descending between the two membranes on either side.
44 689
690
THE THORAX.
The pericardium is a fibre-serous membrane, and consists, therefore, of two layers ;
an external fibrous and an internal serous.
The fibrous layer is a strong, dense, fibrous 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
coats; the strongest being that which incloses the aorta. Below, it is attached
to the central tendon of the Diaphragm ; and, on the left side, to its muscular
fibres.
The vessels receiving fibrous prolongations from this membrane are the aorta,
the superior vena cava, and the pulmonary arteries and veins. As the inferior
cava enters the pericardium, through' the central tendon of the Diaphragm, it
receives no covering from the fibrous layer.
Fig. 351.— Front View of the Thorax. The Ribs and Sternum are represented
in Relation to the Lungs, Heart, and other Internal Organs.
The serous layer invests the heart, and is then reflected on the inner surface
of the pericardium. It consists, therefore, of a visceral and a parietal portion.
The former invests the surface of the heart, and the commencement of the great
vessels, to the extent of two inches from their origin ; from these it is reflected
upon the inner surface of the fibrous layerTtining, below, the upper surface of the
central tendon of the Diaphragm. The serous membrane incloses the aorta and
pulmonary artery in a single tube; but it only partially covers the superior and
inferior venae cavse, and the four pulmonary veins. Its inner surface is smooth
HEART. 691
and glistening, and secretes a thin fluid, which serves to facilitate the movements
of the contained organ.
The arteries of the pericardium are derived from the internal mammary, the
bronchial, the oesophageal, and the phrenic.
The Heart.
The Heart is a hollow muscular organ, of a conical form, placed between the
lungs, and inclosed in the cavity of the pericardium.
Position. The heart is placed obliquely in the chest ; the broad attached end
or base is directed upwards and backwards to the right, and corresponds to the
interval between the fifth and eighth dorsal vertebrae ; the apex is directed for-
wards and to the left, and corresponds to the interspace between the cartilages of
the fifth and sixth ribs, one inch to the inner side, and two inches below the left
nipple. The heart is placed beneath the lower two-thirds of the sternum, and
projects further into the left than into the right 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. Its upper border would correspond to a line drawn across
the sternum, on a level with the upper border of the third costal cartilages ; and
its lower border, to a line drawn across the lower end of the gladiolus, from the
costo-xiphoid articulation of the right side, to the part corresponding to the apex.
Its anterior surface is rounded and convex, directed upwards and forwards, and
formed chiefly by the right ventricle and part of the left. Its posterior surface is
flattened, and rests upon the Diaphragm. The right border is long, thin, and
sharp ; the left border short, but thick and round.
Size. The heart, in the adult, measures about five inches in length, three inches
and a half in breadth in its 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 proportion 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 ; and this is more marked
in men than in women.
Component parts. The heart is subdivided by a longitudinal muscular septum,
into two lateral halves, which are named respectively, from their position, right
and left ; and a transverse constriction divides each half of the organ into two
cavities, the upper cavity on each side being called the auricle, the lower the
ventricle. The right is the venous side of the heart, receiving into its auricle the
dark venous blood from the entire body, by the superior and inferior venae cava3, and
coronary sinus. From the auricle, the blood passes into the right ventricle ; and
from the right ventricle, through the pulmonary artery, into the lungs. The
blood, arterialized by its passage through the lungs, is returned to the left side of
the heart by the pulmonary veins, which open into the left auricle ; from the left
auricle the blood passes into the left ventricle, and from the left ventricle is dis-
tributed, by the aorta and its subdivisions, through the entire body. This con-
stitutes the circulation of the blood in the adult.
This, division of the heart into four cavities is indicated upon its surface in the
form of grooves. Thus, the great transverse groove separating the auricles from
the ventricles is called the auriculo-ventricular groove. It is deficient, in front,
from being crossed by the root of the pulmonary artery, and contains the trunk
of the nutrient vessels of the heart. The auricular portion occupies the base of
the heart, and is subdivided into two cavities by a median septum. The two
ventricles' are also separated into a right and left, by two longitudinal furrows,
which are situated, one on its anterior, the other on its posterior surface ; these
extend from the base to 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.
692 THE THORAX.
Each of these cavities should now be separately examined.
The Eight Aueicle is a little larger than the left, its walls somewhat thinner,
measuring about one line; and its cavity is capable of containing about two
ounces. It consists of two parts, a principal cavity or sinus, and an appendix
auriculae.
The sinus is the large quadrangular-shaped cavity, placed betAveen the two
venge cavee ; its walls are extremely thin, and it is connected below with the right
Fig. 352. — The Right Auricle and Ventricle laid open,
the anterior walls of both being removed.
Xn'stle yarseri th
Jtigit Auricula -Ymtriculaj* evvniny
ventricle, and, Internally, with the left auricle, being free in the rest of its extent.
The appendix auriculae, so called from its fancied resemblance to a dog's ear,
is a small conical muscular pouch, the margins of which present a dentated edge.
It projects from the sinus forwards and to the left side, overlapping the root of
the pulmonary artery.
To examine the interior of the auricle, a transverse incision should be made along its ventri-
cular margin, from its right border to the appendix ; and, from the middle of this, a second inci-
sion should be carried upwards, along the inner side of the two venae cavae.
The following parts present themselves for examination : —
/'Superior vena cava. Relics of Foetal j Annulus ovalis.
[Inferior vena cava. structure. \ Fossa ovalis.
Openings. (Coronary sinus. Musculi pectinati.
'Foramina Thebesii. -rT ■, j Eustachian.
vAuriculo-ventricular. { Coronary.
HEART— RIGHT AURICLE. 693
OPENINGS. The superior vena cava returns the blood from the upper half of
the body, and opens into the upper and front part of the auricle, the direcikm of
its orifice being downwards and forwards.
The inferior vena cava, larger than the superior, returns the blood from the
lower half of the body, and opens into the lowest part of the auricle, near the
septum, the direction of its orifice being upwards and inwards. The direction of
a current of blood through the superior vena cava would consequently be towards
the auriculo-ventricular orifice; whilst the direction of the blood through the
inferior cava would be towards the auricular septum. This is the normal direc-
tion of the two currents in foetal life.
The tuberculum Lower i is a small projection on the right wall of the auricle,
between- the two venae cavae. This 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 superior vena cava towards the auriculo-ventricular opening.
The coronary sinus opens into the auricle, between the inferior vena 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. The sinus, before entering the auricle, is considerably
dilated. Its wall is partly muscular, and, at its junction with the great coronary
vein, is somewhat constricted, and furnished with a valve, consisting of two
unequal segments.
The foramina Thebesii are numerous minute apertures, the mouths of small
veins {venae cordis minimse), which open on various parts of the inner surface of the
auricle. 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 auriculo-ventricular opening is the large oval aperture of communication
between the auricle and ventricle, to be presently described.
Valves. The Eustachian valve is situated between the anterior margin of the
inferior cava 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, containing a
few muscular fibres.
In the foetus, this valve is of large size, and serves to direct the blood from the
inferior vena cava, through the foramen ovale, into the left auricle.
In the adult, it is . occasionally persistent, and may assist in preventing the
reflux of blood into the inferior vena cava ; more commonly, it is small, and its free
margin presents a cribriform or filamentous appearance ; occasionally, it is alto-
gether wanting.
The coronary valve 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 foetus. It is situated at the lower part of the septum auricu-
larum, above the orifice of the inferior vena cava.
The annulus ovalis is the prominent oval margin of the foramen ovale. It is
most distinct above, and at the sides; below, it is deficient. A small slit-like
valvular opening is occasionally found, at the upper margin of the fossa ovalis,
which leads upwards, beneath the annulus, into the left auricle ; it is the remains
of the aperture between the two auricles in the foetus.
The musculi pectinati are small, prominent muscular columns, which run across
the inner surface of the appendix auriculae, and adjoining portion of the wall of
the sinus. They have received the name, pectinati, from the fancied resemblance
they bear to the teeth of a comb.
094 THE THORAX.
The Right Ventkicle is triangular in form, and extends from the right auricle
to near the apex. Its anterior or upper surface is rounded and convex, and forms
the larger part of the front of the heart. Its posterior or under surface is flattened,
rests upon the Diaphragm, and forms only a small part of this surface. Its inner
wall is formed by the partition between the two ventricles, the septum ventricu-
lorum, the surface of which is convex, and bulges into the cavity of the right
ventricle. Superiorly, the ventricle forms a conical prolongation, the infundi-
bulum or conus arteriosus, from which the pulmonary artery arises. The walls of
the right ventricle are thinner than those of the left, the proportion between them
being as 1 to 2 (Bizot). The thickest part of the wall is at the base, and it
gradually becomes thinner towards the apex. Its cavity, which equals that of the
left ventricle, is capable of containing about two fluid ounces.
To examine its interior, an incision should be made a little to the right of the anterior ven-
tricular groove from the pulmonary artery to the apex of the heart, and from thence carried up
along the right border of the ventricle, as far as the auriculo-ventricular opening.
The following parts present themselves for examination : —
~ . j Auriculo-ventricular.
penings . . j Opening of the pulmonary artery.
■y i j Tricuspid.
* ' * I Semilunar.
And a muscular and tendinous apparatus connected with the tricuspid valves : —
Columnae carneae. Chordae tendineEe.
The auriculo-ventricular orifice 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, and corresponds to the centre of the sternum
between the third costal cartilages. The opening is about an inch in diameter,
oval from side to side, surrounded by a fibrous ring, covered by the lining mem-
brane of the heart, and is rather larger than the corresponding aperture on the
left side, being sufficiently large to admit the ends of three fingers. It is guarded
by the tricuspid valve.
The opening of the pulmonary artery is circular in form, and situated at the
summit of the conus arteriosus, close to the septum ventriculorum. It is placed
on the left side of the auriculo-ventricular opening, upon the anterior aspect of
the heart, and corresponds to the upper border of the third costal cartilage of the
left side, close to the sternum. Its orifice is guarded by tkje semilunar valves.
The tricuspid valve consists of three segments of a triangular or trapezoidal
shape, formed by a duplicature of the lining membrane of the heart, strengthened
by a layer of fibrous tissue, and containing, according to Kurschner and Senac,
muscular fibres. These segments are connected by their bases to the auriculo-
ventricular orifice, 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 num-
ber of delicate tendinous cords, the chordse tendinese. The largest and most mov-
able segment is placed towards the left side of the auriculo-ventricular opening
interposed between it and the pulmonary artery. Another segment corresponds
to the front of the ventricle ; and. a third to its posterior wall. The central part of
each segment is thick and strong ; and the lateral margins are thin and indented.
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
«egment.
HEART— LEFT AURICLE. 695
The columnse carnese are the rounded muscular columns which project from
nearly the whole of the inner surface of the ventricle, excepting near the opening
of the pulmonary artery. They may be classified, according to their mode of
connection with the ventricle, into three sets. The first set merely form prominent
ridges on the inner surface of the ventricle, being attached by their entire length
on one side, as well as by their extremities. Tho second set are attached by
their two extremities, but are free in the rest of their extent ; whilst the third set
(columnse papillares), three or four in number, are attached by one extremity to
the Avail of the heart, the opposite extremity giving attachment to the chordse
tendinese.
The semilunar valves, three in number, guard the orifice of the pulmonary artery.
They consist of three semicircular folds, formed by a duplicature of the lining
membrane, 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 upwards in the course of the vessel, against the sides
of which they are pressed during the passage of the blood along its canal. 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 fibro-
cartilaginous nodule, called corpus Arantii. From this nodule, tendinous fibres
radiate through the valve to its attached margin, and these fibres form a consti-
tuent part of its substance throughout its whole extent, excepting two narrow
lunated portions, placed one on either side of the nodule, immediately behind 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
pressed against the sides of its cylinder, and the course of the blood along the tube
is uninterrupted ; 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 fibro-cartilagi-
nous nodules filling up the small triangular space that would be otherwise left by
the approximation of the three semilunar folds.
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 (sinuses of Valsalva). Similar sinuses exist between the semilunar
valves and the commencement of the aorta ; they are larger than the pulmonary
sinuses.
The Left Auricle is rather smaller but thicker than the right, measuring about
one line and a half; it consists of two parts, a principal cavity or sinus, and an
appendix auriculae.
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 septum auricu-
larum ; and behind, it receives on each side the pulmonary veins, being free in
the rest of its extent.
The appendix auriculae is somewhat constricted at its junction with the auricle;
it is longer, narrower, and more curved than that of the right side, and its mar-
gins more deeply indented, presenting a kind of foliated appearance. Its direction
is forwards towards the right side, overlapping the root of the pulmonary
artery.
In order to examine its interior, a horizontal incision should be made along the attached border
of the auricle to the ventricle ; and, from the middle of this, a second incision should be carried
upwards.
The following parts then' present themselves for examination : —
The openings of the four pulmonary veins.
Auriculo- ventricular opening.
Musculi pectinati.
696
THE THORAX.
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 is the large oval aperture of communication
between the auricle and ventricle. It is rather smaller than the corresponding
opening on the opposite side.
The musculi pectinati are fewer in number and smaller than on the right side ;
they are confined to the inner surface of the appendix.
On the inner surface of the septum auricularum may be seen a lunated impres-
sion, bounded below by a crescentic ridge, the concavity of which is turned
upwards. This depression is just above the fossa ovalis in the right auricle.
Ft*
353. — Tlie Left Auricle and Ventricle laid open,
the Anterior Walls of both being removed.
passed thro' Aortic opening
The Left Yenteicle is longer and more conical in shape than the right ven-
tricle. It forms a small part of the left side 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 ventricle, the proportion being as 2 to 1 (Bizot). They
are also thickest in the broadest part of the ventricle, becoming gradually thinner
towards the base, and also towards the apex, which is the thinnest part.
Its cavity should be opened by making an incision through its anterior wall along the left side
of the ventricular septum, and carrying it round the apex and along its posterior surface to the
auriculo-ventricular opening.
The following parts present themselves for examination : —
Auriculo-ventricular. y 1 i Mitral.
Aortic. • ( Semilunar
Chordaa tendinere. Columnge carneas.
Openings
HEART— LEFT VENTRICLE. 697
he auricula-ventricular opening is placed to the left of the aortic orifice, be-
neath the right auriculo-ventricular opening, opposite the centre of the sternum.
It is a little smaller than the corresponding aperture of the opposite side ; and,
like it, is broader in the transverse, than in the antero-posterior, diameter. It is
surrounded by a dense fibrous ring, covered by the lining membrane of the heart
and is guarded by the mitral valve.
The aortic opening is a small circular aperture, in front and to the right side of
the auriculo- ventricular, from which it is separated by one of the segments of the
mitral valve. Its orifice is guarded by the semilunar valves. Its position corre-
sponds to the sternum, on a line with the lower border of the third left costal
cartilage.
The mitral valve is attached to the circumference 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 is placed in front, between the auriculo-ventricular and aortic ori-
fices, and is said to prevent the filling of the aorta during the distension of the
ventricle. Two smaller segments are usually found at the angle of junction of the
larger. The mitral valves are furnished with chordae tendineee ; their mode of
attachment is precisely similar to those on the right side, but they are thicker,
stronger, and less numerous.
The semilunar valves surround the orifice of the aorta; 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
lunulas are more distinct, and the corpora Arantii larger and more prominent.
Between each valve and the cylinder of the aorta is a deep depression, forming
the sinus aortici (sinuses of Valsalva) ; they are larger than those at the root of the
pulmonary artery.
The columnse carnese admit of a subdivision into three sets, like those upon
the right side ; but they are smaller, more numerous, and present a dense interlace-
ment, especially at the apex, and upon the posterior wall. Those attached by one
extremity only, the musculi papillares, are two in number, being connected one to
the anterior, the other to the posterior wall ; they are of large size, and terminate
by free rounded extremities, from which the chordas tendineoa arise.
The Endocardium is the serous membrane which lines the internal surface of
the heart ; it assists in forming, by its reduplications, the valves contained in this
organ, and is continuous with the lining membrane of the great bloodvessels.
It is a thin, smooth, transparent membrane, giving to the inner surface of the
heart its glistening appearance. It 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 carneae ; but
thicker on the smooth part of the auricular and ventricular walls, and on the tips
of the musculi papillares.
Structure of the Heart. The heart consists of muscular fibres, and of
fibrous rings which serve for their attachment.
The fibrous rings 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 left one is closely
connected, by its right margin, with the aortic arterial ring. Between these and
the right auriculo-ventricular ring, is a fibro-cartilaginous mass ; and in some of
the larger animals, as the ox and elephant, a portion of bone.
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
698 THE THORAX.
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 dilated to form the sinuses of Valsalva.
The muscular structure of the heart consists of bands of fibres, which present
an exceedingly intricate interlacement. They are of a deep red color, and marked
with transverse striae.
The muscular fibres of the heart admit of a subdivision into two kinds, those of
the auricles, and those of the ventricles, which are quite independent of one another.
Fibres of the auricles. These are disposed in two layers, a superficial layer
common to both cavities, and a deep layer proper to each. The superficial fibres
are most 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 auricularum. The internal or deep fibres proper
1 to each auricle consist of two sets, looped, and annular fibres. The looped fibres
pass upwards over each auricle, being attached by both extremities to the corre-
sponding auriculo- ventricular rings, in front and behind. The annular fibres sur-
round the whole extent of the appendices auriculae, and are continued upon the
walls of the venae cavae and coronary sinus on the right side, and upon the pul-
monary 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, as in the auricles, are disposed in layers, some
of which' are common to both ventricular cavities, whilst others belong exclusively
to one ventricle, the latter being chiefly found towards the base of the heart.
The greater majority of these fibres are connected by both ends with the auriculo-
ventricular fibrous rings, either directly or indirectly through the chordae ten-
dineae ; some, however, are attached to the fibrous rings surrounding the arterial
orifices.
The superficial fibres are either longitudinal, or, more commonly, oblique or spiral
in their direction, and towards the apex are arranged in the form of twisted loops ;
the deeper fibres are circular.
The spiral fibres .are disposed in layers of various degrees of thickness ; the
most superficial, on the front of the ventricles, run obliquely from right to left,
and from above downwards. On the back of the ventricles they are directed
more vertically, and pass from left to right.
The superficial fibres coil inwards at the apex of the heart, round which they
are arranged in a whorl-like iorm, called the vortex, dipping beneath the edge of
the deeper and shorter layers. If these fibres are carefully uncoiled, in a heart
previously boiled, the cavity < f the left, and then that of the right ventricle, will
be exposed at this point. The layers of fibres successively met with have a simi-
lar arrangement ; the more superficial and longer turning inwards, and including
the deeper and shorter bands. All these fibres ascend and spread out upon the
inner surface of the ventricles, forming the walls, the septum, and the musculi
papillares, which project from these cavities ; and they are finally inserted into
the auriculo-ventricular fibrous rings, or, indirectly, through the chordae tendineae.
Of these spiral fibres, some enter at the interventricular furrows, and surround
either ventricle singly ; others pass across the furrows, and embrace both cavities.
On tracing those which form the vortex, back into the interventricular septum,
they become interlaced with similar fibres from the right ventricle, and ascend
vertically upon the right side of the septum, as far as its base, in the form of a
long and broad band.
Circular fibres. The circular fibres are situated deeply in the substance of
VASCULAR SYSTEM OF TIIE FCETUS. 699
the heart ; towards the base they enter the anterior and posterior longitudinal
furrows, so as to include each cavity singly, or, passing across them, surround
both ventricles, more fibres passing across the posterior than the anterior furrow.
They finally ascend in the substance of the ventricle, to be inserted into the fibrous
rings at its base.
Vessels and Nerves. The arteries supplying the heart are the anterior and pos-
terior coronary.
The veins accompany the arteries, and terminate in the right auricle. They are
the great cardiac vein, the small or anterior cardiac veins, and the venae cordis
minimae (venae Thebesii).
The lymphatics terminate in the thoracic and right lymphatic ducts.
The nerves are derived from the cardiac plexuses, which are formed partly from
the spinal, and partly from the sympathetic system. They are freely distributed
both on the surface, and in the substance of the heart ; the separate filaments being
furnished with small ganglia. These have been figured by Remak, but the more
extended investigations of Dr. Robert Lee have shown them tp exist in great
abundance, both in the nerves distributed to the surface, and in those in the
interior of the organ.
Peculiarities in the Vascular System of the Foetus.
The chief peculiarities in the heart of the foetus are the direct communication
between the two auricles by 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 as 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, towards birth, the ventricular
portion becomes the larger. The thickness of both ventricles is, at first, about
equal ; but, towards birth, the left becomes much the thicker of the two.
The foramen ovale is situated at the lower and back part of the septum
auricularum. Through it the auricles communicate with each other. It attains
its greatest size at the sixth month.
The Eustachian valve is developed from the anterior border of the inferior vena
cava, at its entrance in the auricle, and, rising up on the left side of the opening
of this vein, serves to direct the blood from the inferior vena cava 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 descending aorta, by means of the ductus
arteriosus, and the communication between the internal iliac arteries and the
placenta, by the umbilical arteries.
The ductus arteriosus is a short tube, about half an inch in length at birth, and
of the diameter of a goose-quill. It connects the left branch of the pulmonary
artery with the termination of the arch of the aorta, just beyond the origin of the
left subclavian artery. It conducts the chief part of the blood of the right ventri-
cle into the descending aorta.
The umbilical or hypogastric arteries arise from the internal iliacs, in addition
to the usual branches given off' from these vessels in the adult. Ascending along
the sides of the bladder to its fundus, 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 return the blood to the placenta which has been
circulated in the system of the foetus.
The peculiarity in the venous system of the foetus is the communication
established between the placenta and the liver and portal vein, through the
umbilical vein, and with the inferior vena cava by the ductus venosus.
TOO
THE THORAX.
Fcetal Circulation.
In the following plan the figured arrows represent the kind of \>lood, as well as the
direction which it takes in the vessels. Thus — arterial blood is figured >» > ;
venous blood, >» •••>; mixed (arterial and venous blood), #ti> i ' *if ,
Fig. 354.— Plan of the Foetal Circulation.
Intrtml Mac JGC
The arterial blood destined for the nutrition of the foetus is carried from the
placenta to the foetus, along the umbilical cord, by the umbilical vein. The
umbilical vein enters the abdomen at the umbilicus, and passes upwards along the
FCETAL CIRCULATION. T01
free margin of the suspensory ligament of the liver, to the under surface of this
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 lobus 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 onwards,
under the name of the ductus venosus, and joins the left hepatic vein at the
point of junction of this vessel with the inferior vena cava. The blood, there-
fore, which traverses the umbilical vein, reaches the inferior vena cava in three
different ways. The greater quantity circulates through the liver with the portal
venous blood, before entering the cava by the hepatic veins ; some enters the liver
directly, and is also returned to the inferior cava by the hepatic veins ; the smaller
quantity passes directly into the vena cava, by the junction of the ductus venosus
witli the left hepatic vein.
In the inferior cava, the blood carried by the ductus venosus and hepatic veins
becomes mixed with that returning from the lower extremities and viscera 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, from whence 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 branches of
the superior vena cava to the right auricle, where it becomes mixed with a small
portion of the blood from the inferior cava. From the right auricle, it descends
over the Eustachian valve into the right ventricle; and, from the right ventricle,
into the pulmonary artery. The lungs of the foetus being solid, and almost
impervious, only a small quantity of blood is distributed to them, by the right
and left pulmonary arteries, which is returned by the pulmonary veins to the left
auricle ; the greater part passes through the ductus arteriosus into the commence-
ment of the descending aorta, where it becomes mixed with a small quantity of
blood transmitted by the left ventricle into the aorta. Along 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 double purpose of a respiratory and nutritive
organ, receiving the venous blood from the foetus, and returning it again re-oxy-
genated, and charged with additional nutritive material.
2. That nearly the whole of the blood of the umbilical vein traverses the liver
before entering the inferior vena cava ; hence the large size of this organ, especially
at an early period of foetal life.
3. That the right auricle is the point of meeting of a double current, the
blood in the inferior vena cava being guided by the Eustachian valve into the left
auricle, whilst that in the superior vena cava descends into the right ventricle. At
an early period of foetal life, it is highly probable that the two streams are quite
distinct ; for the inferior vena cava opens almost directly into the left auricle, and the
Eustachian valve would exclude the current along the tube from entering the
right ventricle. At a later period, as the separation between the two auricles
becomes more distinct, it seems probable that some slight mixture of the two
streams must take place.
4. The blood carried from the placenta to the foetus by the umbilical vein,
mixed with the blood from the inferior vena cava, passes almost directly to the arch
of the aorta, and is distributed by the branches of this vessel to the head and upper
extremities; hence the large size and perfect development of these parts at birth.
5. The blood contained in the descending aorta, chiefly derived from that
which has already circulated through the head and limbs, together with a small
102 THE THORAX.
quantit}'- from the left ventricle, is distributed to the lower extremities; hence the
small size and imperfect development of these parts at birth.
Changes m 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.
The foramen ovale becomes gradually closed by about the tenth day after birth,
a valvular fold rising up on the left side of its margin, and ultimately above its
upper part ; this valve becomes adherent to the margins of the foramen for the
greater part of its circumference, but, above, a valvular 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 concavity of the arch of the aorta.
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 supe-
rior vesical artery ; and the part between the fundus of the bladder and the
umbilicus becomes obliterated between the second and fifth days after birth, and
forms the anterior true ligament of this viscus.
The umbilical vein and 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 latfler the fibrous cord,
which, in the adult, may be traced along the fissure of the ductus venosus.
Organs of Voice and Eespiration.
pi*
355.— Side View of the Thyroid
and Cricoid Cartilages.
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
fore part 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 this
cavity.
The larynx is narrow and cylindrical below, but broad above, where it presents
the form of a triangular box, being flattened behind and at the sides, whilst in
front it is bounded by a prominent vertical ridge. It is composed of cartilages,
connected together by ligaments, moved by numerous muscles, lined by mucous
membrane, and supplied with vessels and nerves.
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 Tliyroid (0vp«ov dSof, like a shield) is the largest cartilage of the larynx.
It consists 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. This projection is subcu-
taneous, more distinct in the male than in
the female, and occasionally separated from
the integument by a bursa mucosa.
Each lamella is quadrilateral in form.
Its outer surface presents an oblique
ridge, which passes downwards and for-
wards from a tubercle, situated near the
root of the superior cornu. This ridge
gives attachment to the Ster no -thyroid
and Thyro-hyoid muscles; the portion of
cartilage included between it and the poste-
rior border, to part of the Inferior constric-
tor muscle.
The inner surface of each ala is smooth,
concave, and covered by mucous membrane
above and behind ; but in front, in the re-
ceding angle formed by their junction, are
attached the epiglottis, the true and false
chordae vocales, the Thyro-arytenoid and
Thyro-epiglottidean muscles.
The upper border of the thyroid carti-
lage is deeply notched in the middle line,
immediately above the pomum Adami,
whilst on either side it is slightly concave.
This border gives attachment throughout its whole extent to the thyro-hyoid
membrane.
The lower border is connected to the cricoid cartilage, in the median line, by the
cri co-thyroid membrane ; and, on each side, by the Crico-thyroid muscle.
703
T04
ORGANS OF YOICE AND RESPIRATION.
Fig. 356.— The Cartilajr^s of the Larynx.
Posterior View.
EPIGLOTTIS
The posterior borders, thick and rounded, terminate, above, in the superior cornua ;
and, below, in the inferior cornua. The two superior cornua are long and narrow,
directed backwards, upwards, and inwards ; and terminate in a conical extremity,
which gives attachment to the thyro-hyoid ligament. The two inferior cornua
are short and thick ; they pass forwards and inwards, and present, on their inner
surfaces, a small, oval, articular facet for articulation with the side of the cricoid
cartilage. The posterior border receives the insertion of the Stylo-ph.aryngeus
and Pal&to-pharyngeus muscles on each side.
The Cricoid Cartilage is so
called from its resemblance to
a signet-ring (xpi'xoj «5o$, like
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.
Its anterior half is narrow,
convex, affording attachment in
front and at the sides to the
Crico-thyroid muscles, and, be-
hind those, to part of the Inferior
constrictor.
Its posterior half is very
broad, both from side to side
and from above downwards ; it
presents in the middle line a
vertical ridge for the attachment
of the longitudinal fibres of the
oesophagus, and on either side
of this is a broad depression for
the Crico-arytsenoideus posticus
muscle.
At the point of junction of
the two halves of the cartilage
on either side, 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 con-
nected to the upper ring of the
trachea by fibrous membrane.
Its upper border is directed ob-
liquely upwards and backwards,
owing to the great depth of its
posterior surface. It gives at-
tachment, in front, to the crico-
thyroid membrane ; at the sides,
to part of the same membrane
and to the lateral Crico-aryte-
noid muscle ; behind, the highest point of the upper border is surmounted on each
side by a smooth, oval surface, for articulation with the arytenoid cartilage. Be-
tween the articular surfaces is a slight notch, for the attachment of part of the
Arytsenoideus muscle.
The inner surface of the cricoid cartilage is smooth, and lined by mucous mem-
brane.
The Arytenoid Cartilages are so called from the resemblance they bear, when
ruKi/j^wi CaTtlLafj,
ARYTENOID-
insertion *f
CRlCO-AfirT*NOiO
P«ftTlCl.SkTlATi*AM»
CRICOID
Arl/ettla r facet
Ar-t/eufftr fnem,
f<rr Infer, Ctirnu
tf T Ay sold C»
Arytenoid Cart9.". Ao##
CARTILAGES OF THE LARYNX. 705
approximated, to the mouth of a pitcher (apyratva-tlSos, like a pitcher). They are
two iii number, and situated at the upper border of the cricoid cartilage, at the
back of the larynx. Each cartilage is pyramidal in form, and presents for ex-
amination three surfaces, a base, and an apex.
The posterior surface is triangular, smooth, concave, and lodges part of the
Arytenoid muscle.
The anterior surface, somewhat convex and rough, gives attachment to the
Thyro-arytenoid muscle, and to the false vocal cord.
The internal surface is narrow, smooth, and flattened, covered by mucous mem-
brane, and lies almost in apposition with the cartilage of the opposite side.
The base of each cartilage is broad, and presents a concave smooth surface, for
articulation with the cricoid cartilage. Of its three angles, the external one is
short, rounded, and prominent, receiving the insertion of the posterior and lateral
Crico-arytenoid muscles. The anterior one, also prominent, but more pointed,
gives attachment to the true vocal cord.
The apex of each cartilage is pointed, curved backwards and inwards, and
surmounted by a small conical-shaped, cartilaginous nodule, corniculum laryngis
(cartilage of Santorini). This cartilage is sometimes united to the arytenoid, and
serves to prolong it backwards and inwards. To it is attached the aryteno-
epiglottidean fold.
The cuneiform, cartilages (cartilages of Wrisberg) are two small, elongated,
cartilaginous 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 {aryteno-epigloltidean fold); they give rise to the small whitish eleva-
tions on the inner surface of the mucous membrane, just in front of the arytenoid
cartilages.
The epiglottis is a thin 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. During respiration, its direction is vertically upwards, its free
extremity curving forwards towards the base of the tongue ; but when the larynx
is drawn up beneath the base of the tongue during deglutition, it is carried
downwards and backwards, so as to completely close the opening of the larynx.
Its free extremity is broad and rounded ; its attached end is long and narrow,
and connected to the receding angle between the two alas of the thyroid cartilage,
just below the median notch, by a long, narrow, ligamentous band, the thyro-
epiglottic ligament. 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 forwards towards the tongue, and
covered by mucous membrane, which is reflected on to the sides and base of
this organ, forming a median and two lateral folds, the glosso-epiglottidean
ligaments.
Its posterior or laryngeal surface is smooth, concave from side to side, convex
from above downwards, and covered by mucous membrane; when this 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.
Structure. The epiglottis, cuneiform cartilages, and cornicula laryngis are
composed of yellow cartilage, which shows little tendency to ossification ; but the
other cartilages resemble in structure the costal cartilages, becoming more or less
ossified in old age.
Ligaments. The ligaments of the larynx are extrinsic, as those connecting the
thyroid cartilage with the os hyoides; and intrinsic, as those connecting the
several cartilaginous segments to each other.
The ligaments connecting the thyroid cartilage with the os hyoides are
three in number; — the thyro-hyoid membrane, and the two lateral thyro-hyoid
ligaments.
The thyro-hyoid membrane is a broad, fibro-elastic, membranous layer, attached
45
•706
ORGANS OF VOICE AND RESPIRATION
below to the upper border of the thyroid cartilage, and above to the upper border
of the inner surface of the hyoid bone ; being separated from the posterior surface
of the hyoid bone by a synovial bursa. It is thicker in the middle line than at
either side, in which situation it is pierced by the superior laryngeal vessels and
nerve.
The two lateral thyro-hyoid ligaments are rounded, elastic cords, which pass
between the superior cornua of the thyroid cartilage, to the extremities of the
greater cornua of the hyoid bone. A small cartilaginous nodule (cartilago triticea),
sometimes bony, is found in each.
The ligaments connecting the thyroid cartilage to the cricoid are also three in
number ; the crico-thyroid membrane, and the capsular ligaments and synovial
membrane.
The crico-thyroid membrane is composed mainly of yellow elastic tissue. It is
of triangular shape ; thick in front, where it connects together the contiguous
margins of the thyroid and cricoid cartilages ; thinner at each side, where it ex-
tends from the superior border of the cricoid cartilage to the inferior margin of
the true vocal cords, with which it is closely united in front.
The anterior portion of the crico-thyroid membrane is convex, concealed on
each side by the Crico-thyroid muscle, subcutaneous in the middle line, and crossed
horizontally by a small anastomotic arterial arch, formed by the junction of the
crico-thyroid branches on either side.
The lateral portions are lined internally by mucous membrane, and covered by
the lateral Crico-arytenoid and Thyro-arytenoid muscles.
A capsular ligament incloses the articulation of the inferior cornu of the
thyroid with the side of the cricoid, on each side. The articulation is lined
by synovial membrane.
The ligaments connecting the arytenoid cartilages to the cricoid are two thin
and loose capsular ligaments connecting together the articulating surfaces, lined
internally by synovial membrane, and strengthened behind by a strong posterior
crico-arytenoid ligament, which extends from the cricoid to the inner and back
part of the base of the arytenoid cartilage.
The ligaments of the epiglottis are the hyo-epiglottic, the thyroepiglottic, and
the three glosso-epiglottic folds of mucous membrane which connect the epiglottis
to the sides and base of the tongue. The latter have been already described.
The hyo-epiglottic ligament is an elastic fibrous band, which extends from the
anterior surface of the epi-
Fig. 357.— The Larynx and adjacent parts, glottis, near its apex, to the
posterior surface of the body
of the hyoid bone.
The thyroepiglottic ligament
is a long, slender, elastic cord,
which connects the apex of the
epiglottis with the receding
angle of the thyroid cartilage,
immediately beneath the me-
dian notch, above the attach-
ment of the vocal cords.
Interior of the Larynx. The
superior aperture of the larynx
(fig. 357) is a triangular or
cordiform opening, narrow
in front, wide behind, and
sloping obliquely downwards
and backwards. 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
seen from above.
Arytenoid- cart ■
CAVITY OF LARYNX— GLOTTIS— VOCAL CORDS.
TOT
membrane, inclosing ligamentous and muscular fibres, stretched between the sides
of the epiglottis and the apex of the arytenoid cartilage : these are the aryteno-
epiglottidean folds, on the margins of which the cuneiform cartilages form a more
or less distinct whitish prominence.
The cavity of the larynx extends from the aperture behind the epiglottis to the
lower border of the cricoid cartilage. It is divided into two parts by the
projection inwards of the vocal cords and Thyro-arytenoid muscles; between
the two cords is a long and narrow triangular fissure or chink, the glottis or rima
ghttidis. The portion of the cavity of the larynx above the glottis is broad and
triangular in shape above, and corresponds to the interval between the alas of the
thyroid cartilage ; the portion below the glottis is at first elliptical, and, lower
down, of a circular form.
The glottis or rima ghttidis is the interval between the inferior vocal cords.
The two superior or false vocal cords are placed above the latter, and are formed
almost entirely hj a folding inwards of the mucous membrane ; whilst the two
inferior or true vocal cords are thick, strong, and formed partly by mucous mem-
brane, and partly by ligamentous fibres. Between the true and false vocal cords,
on each side, is an oval depression, the sinus or ventricle of the larynx, which
leads upwards, on the outer side of the superior vocal cord, into a csecal pouch of
variable size, the sacculus laryngis.
The rima ghttidis is the narrow fissure or chink between the inferior or true
vocal cords. It is the narrowest part of the cavity of the larynx, and cor-
responds to the level of the arytenoid
K*
358. — Vertical Section of the Larynx
and upper part of the Trachea.
irybncd
wit.'
cartilages. Its length, in the male,
measures rather less than an inch, its
breadth when dilated varying at its
widest part from a third to half an
inch. In the female, these measure-
ments are less by two or three lines.
The form of the glottis varies. In a
quiescent state, it is a narrow fissure,
a little enlarged and rounded behind.
In inspiration, it is widely open, some-
what triangular, the base of the triangle
directed backwards, and corresponding
to the space between the separated
arytenoid cartilages. In expiration,
it is smaller than during inspiration.
When sound is produced, it is more
narrowed, the margins of the aryte-
noid cartilages being brought into
contact, and the edges of the vocal
cords approximated and made parallel ;
the degree of approximation and ten-
sion corresponding to the height of
the note produced.
The superior or false vocal cords, so
called because they are not directly
concerned in the production of the
voice, are two folds of mucous mem-
brane, inclosing a delicate narrow
fibrous band, the superior thyro-arytenoid ligament. This ligament consists of a
thin band of elastic tissue, attached in front to the angle of the thyroid cartilage
below the epiglottis, and behind to the anterior surface of the arytenoid cartilage.
The lower border of this ligament, inclosed in mucous membrane, forms a free
crescentic margin, which constitutes the upper boundary of the ventricle of the
larynx.
708 ORGANS OF VOICE AND RESPIRATION.
The inferior or true vocal cords, so called from their being concerned in the
production of sound, are two strong fibrous bands {inferior thyro-arytenoid liga-
ments), covered externally 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 two alae of the thyroid cartilage, and behind to the anterior an°-le of
the base of the arytenoid. 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-arytaenoideus muscle lies
parallel with it. It is covered internally by mucous membrane, which is extremely
thin, and closely adherent to its surface.
The ventricle of the larynx 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 true vocal cord ; externally, by the
corresponding Thyro-arytaenoideus muscle. The anterior part of the ventricle
leads up by a narrow opening into a cascal pouch of mucous membrane of variable
size, called the laryngeal pouch.
The sacculus laryngis 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 ; it is conical in form, and curved slightly
backwards, resembling in form a Phrygian cap. On the surface of its mucous
membrane are the openings of sixty or seventy small follicular glands, which are
lodged in the submucous areolar tissue. This sac is inclosed in a fibrous capsule,
continuous below with the superior thyro-arytenoid ligament; its laryngeal
surface is covered by the Arytaeno-epiglottideus inferior muscle {Compressor sac-
culi laryngis, Hilton), whilst its exterior is covered by the Thyro-epiglottideus
muscle. These muscles compress the sacculus laryngis, and discharge the secre-
tion it contains upon the chordae vocales, the surfaces of which it is intended to
lubricate.
Muscles of the Larynx. The intrinsic muscles of the larynx are eight in
number ; five of which are the muscles of the chordae vocales and rima glottidis,
and three are connected with the epiglottis.
The five muscles of the chordae vocales and rima glottidis are the
Crico-thyroid. Arytaenoideus.
Crico-arytaenoideus posticus. Thyro-arytaenoideus.
Crico-aryta3noideus lateralis.
The Crico-thyroid is triangular in form, and situated at the fore part and side
of the cricoid cartilage. It arises from the front and lateral part of the cricoid
cartilage ; its fibres diverge, passing obliquely upwards and outwards, to be
inserted into the lower and inner borders of the thyroid cartilage ; from near the
median line in front, as far back as the inferior cornu.
The inner borders of these two muscles are separated in the middle line by a
triangular interval, occupied by the crico-thyroid membrane.
The Crico-arytaenoideus posticus arises from the broad depression occupying
each lateral half of the posterior surface of the cricoid cartilage ; its fibres pass
upwards and outwards, and converge to be inserted into the outer angle of the
base of the arytenoid cartilage. The upper fibres are nearly horizontal, the
middle oblique, and the lower almost vertical.1
1 Dr. Merkel, of Leipsic, has lately described a muscular slip which occasionally extends
between the outer border of the posterior surface of the cricoid cartilage, and the posterior mar-
gin of the inferior cornu of the thyroid ; this, he 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. Mr. Turner (Edinburgh Medical Journal, Feb. I860) states that it is found
in the ratio of 21.8 per cent. Its action is to fix the lower horn of the thyroid cartilage backwards
and downwards, opposing in some measure the part of the crico-thyroid muscle connected to the
anterior manrin of the horn.
MUSCLES OF THE LARYNX.
709
Fig. 359. — Muscles of Larynx, Side View.
Eight Ala of Thyroid Cartilage removed.
Corni ' aila ^
larvnais
Articular facet
jOrlitfiruiT Cornu. of
Thyroid CartsL
The Crico-arytsenoideus lateralis 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 upwards and
backwards, is inserted into the outer
angle of the base of the arytenoid
cartilage, in front of the preceding
muscle.
The Thyro-arytsenoideus is a broad,
flat muscle, which 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 horizontally backwards and
outwards, to be inserted into the
base and anterior surface of the
arytenoid cartilage. This muscle
consists of two fasciculi. The in-
ferior, the thickest, is inserted into
the anterior angle of the base of the
arytenoid cartilage, and into the ad-
jacent portion of its anterior surface;
it lies parallel with the true vocal
cord, to which it is occasionally ad-
herent. The superior fasciculus,
the thinnest, 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 its mucous lining.
The Aryteenoideus is a single
muscle, filling up the posterior con-
cave surface of the arytenoid carti-
lages. It arises from the posterior
surface and outer border of one
arytenoid cartilage, and is inserted
into the corresponding parts of the
opposite cartilage. It consists of
three planes of fibres ; two oblique,
and one transverse. The oblique
fibres, the most superficial, form
two fasciculi, which pass from the
base of one cartilage to the apex of
the opposite one. The transverse
fibres, the deepest and most nume-
rous, pass transversely across be-
tween the two cartilages ; hence the
Aryteenoideus was formerly con-
sidered as several muscles, under
the names of transversa and obliqui.
A few of the oblique nbres are oc-
casionally continued round the outer
margin of the cartilage, and blend
with the Thyro-arytenoid or the
Arytaeno-epiglottideus muscle.
Fig. 360. — Interior of the Larynx, seen from
above. (Enlarged.)
•riO ORGANS OF VOICE AND RESPIRATION.
The muscles of the epiglottis are the
Thyro-epiglottideus.
Arytseno-epiglottideus superior.
Arytseno-epiglottideus inferior.
The TIiyro-epAglottideus is a delicate fasciculus, which arises from the inner surface
of the thyroid cartilage, just external to the origin of the Thyro-arytenoid muscle,
and. spreading out upon the outer surface of the sacculus laryngis, some of its
fibres are lost in the aryteno-epiglottidean fold, whilst others are continued for-
wards to the margin of the epiglottis {Depressor epiglottidis).
The Arytseno-epiglottideus superior consists of a few delicate muscular fasciculi,
which arise from the apex of the arytenoid cartilage, and become lost in the fold
of mucous membrane extending between the arytenoid cartilage and side of the
epiglottis (aryteno-epiglottidean folds).
The Arytseno-epiglottideus inferior (Compressor sacculi laryngis, Hilton) arises
from the arytenoid cartilage, just above the attachment of the superior vocal cord ;
passing forwards and upwards, it spreads out upon the inner and upper part of
the sacculus laryngis, and is inserted, by a broad attachment, into the margin of the
epiglottis. This muscle is separated from the preceding by an indistinct areolar
interval.
Actions. In considering the actions 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 Crico-aryttenoidei postici ; and
those which close it are the Arytamoideus, and the Crico-arytsenoidei laterales.
2. The muscles which regulate the tension of the vocal cords are the Crico-
thyroidei, which make tense and elongate them, and the Thyro-arytsenoidei, which
relax and shorten them. The Thyro-epiglottideus is a depressor of the epiglottis,
and the Arytseno-epiglottidei constrict the superior aperture of the larynx, com-
press the sacculi laryngis, and empty them of their contents.
The Crico-arytamoidei postici separate the chorda? vocales, and, consequently, open the glottis,
by rotating the base of the arytenoid cartilages outwards and backwards ; so that their anterior
angles, and the ligaments attached to them, become widely separated, the vocal cords, at the
same time, being made tense.
The Crico-arytamoidei laterales close the glottis, by rotating the base of the arytenoid carti-
lages inwards, so as to approximate their anterior angles.
The Arytamoideus muscle approximates the arytenoid cartilages, and thus closes the opening
of the glottis, especially at its back part.
The Crico-thyroid muscles effect the tension and elongation of the vocal cords, by drawing
down the thyroid cartilage over the cricoid.
The Thyro-arytamoidei muscles draw the arytenoid cartilages, together with the part of the
cricoid to which they are connected, forwards towards the thyroid, and thus shorten and relax
the vocal cords.
The Thyro-epiglottidei depress the epiglottis, and assist in compressing the sacculi laryngis.
The Arytazno-epiglottideus superior constricts the superior aperture of the larynx, when it is
drawn upwards, during deglutition, and the opening closed by the epiglottis. The Arylamo-
cpiglottideus inferior, together with some fibres of the Thyro-arytaenoidei, compress the sacculus
laryngis.
The Mucous Membrane of the Larynx is continuous, above, with that lining the
mouth and pharynx, and is prolonged through the trachea and bronchi into the
lungs. It lines both surfaces of the epiglottis, to which it is closely adherent,
and forms the aryteno-epiglottidean folds, which encircle the superior aperture of
the larynx. It lines the whole of the cavity of the larynx ; forms, by its redu-
plication, the chief part of the superior or false vocal cord ; and, from the ven-
tricle, 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 sur-
face of the crico-thyroid membrane, and cricoid cartilage, and is ultimately con-
tinuous with the lining membrane of the trachea. It is covered with columnar
ciliated epithelium, below the superior vocal cord ; but, above this point, the ciliae
are found only in front, as high as the middle of the epiglottis. In the rest of its
extent, the epithelium is of the squamous variety.
TRACHEA.
m
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
arytenoid glands. They exist also in large numbers upon the inner surface of the
sacculus laryugis. None are found on the vocal cords.
Vessels and Nerves. The arteries of the larynx are the laryngeal branches
derived from the superior and inferior thyroid. The veins empty themselves into
the superior, middle, and inferior thyroid veins. The lymphatics terminate in the
deep cervical glands. The nerves are the superior laryngeal, and the inferior or
recurrent laryngeal branches of the pneumogastric nerves, joined by filaments from
the sympathetic. The superior laryngeal nerves supply the mucous membrane of
the larynx, and the Crico-thyroid muscles. The inferior laryngeal nerves supply
the remaining muscles. The Arytenoid muscle is supplied by both nerves.
The Trachea.
The trachea or air-tube is a cartilaginous and membranous cylindrical tube,
Fig. 361. — Front View of Cartilages of Larynx, the Trachea and Bronchi.
712 ORGANS OF VOICE AND RESPIRATION.
flattened posteriorly, extending from the lower part of the larynx, on a level with
the fifth cervieal vertebra, to opposite the third dorsal, where it divides into the
two bronchi, one for each lung. 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 downwards, 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 (in the interval between
these muscles), and, more superficially, by the anastomosing branches between the
anterior jugular veins; in the thorax, it is covered from before backwards by the
first piece of the sternum, the remains of the thymus gland, the arch of the aorta,
the innominate and left carotid arteries, and the deep cardiac plexus. It lies
upon the oesophagus, which is directed to the left, near the arch of the aorta ;
laterally, in the neck, it is in relation with the common 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 interspace between the pleuras, having the
pneumogastric nerve on each side of it.
The Right Bronchus, wider, shorter, and more horizontal in direction than the
left, is about an inch in length, and enters the right lung, opposite the fourth dorsal
vertebra. The vena azygos arches over it, from behind ; and the right pulmonary
artery lies below, and then in front of it.
The Left Bronchus is smaller, more oblique, and longer than the right, being
nearly two inches in length. It enters the root of the left lung, opposite the fifth
dorsal vertebra, about an inch lower than the right bronchus. It crosses in front
of the oesophagus, the thoracic duct, and the descending aorta ; passes beneath the
arch of the aorta, and has the left pulmonary artery lying at first above, and then
in front of it. If a transverse section is made across the trachea, a short distance
above its point of bifurcation, and a bird's-eye view taken of its interior (fig. 362),
the septum placed at the bottom of
Fig. 362. — Transverse Section of the Trachea, ,-, • , \ ,• ,\ . -i i •
just above its bifurcation, with a bird's-eye tn.ls tube> separating the two bronchi,
view of the interior. will be seen to occupy the left of the
jn„£. median line, as was first shown by Mr.
Goodall, of Dublin, so that any solid
body descending the trachea, by virtue
of the laws of gravity, would naturally
be directed towards the right bronchus,
and this tendency is undoubtedly aided
by the larger size of this tube, as
compared with its fellow. This fact
serves to explain why a foreign sub-
stance in the trachea almost universally falls into the right bronchus.
The trachea is composed of imperfect cartilaginous rings, fibrous membrane,
muscular fibres, longitudinal yellow elastic fibres, mucous membrane, and glands.
The Cartilages vary from sixteen to twenty in number ; each forms an imper-
fect ring, which surrounds about two-thirds of the cylinder of the trachea, being
imperfect behind, where the tube is completed by fibrous membrane. The carti-
lages 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. The cartilages are connected together,
at their margins, by an elastic fibrous membrane, which covers both their surfaces ;
and in the space between their extremities, behind, forms a distinct layer. 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 connected by fibrous membrane with the lower border of the cricoid cartilage,
with which, or with the succeeding cartilage, it is sometimes blended.
TRACHEA. 113
The last cartilage is thick and broad in the middle, in consequence of its lower
border being prolonged downwards, and, at the same time, curved backwards, at
the point of bifurcation of the trachea. It terminates on each side in an imper-
fect ring, which incloses the commencement of the bronchi. The cartilage above
the last is somewhat broader than the rest at its centre. Two or more of the
cartilages often unite, partially or completely, and are sometimes bifurcated at
their extremities. They are highly elastic, and seldom ossify, even 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 Muscular Fibres are disposed in two layers, longitudinal and transverse.
The longitudinal fibres are the most external, and arise by minute tendons from
the termination of the tracheal cartilages, and from the fibrous membrane.
The transverse fibres, the most internal, form a thin layer, which extends trans-
versely between the ends of the cartilages, at the posterior part of the trachea.
The muscular fibres are of the unstriped variety.
The Elastic Fibres are situated beneath the mucous membrane, inclosing the
entire cylinder of the trachea; they are most abundant at its posterior part, where
they are collected into longitudinal bundles.
The Mucous Membrane lining the tube is covered with columnar ciliated
epithelium. It is continuous with that lining the larynx.
The Tracheal Glands are found in great abundance at the posterior part of the
trachea. They are small, flattened, ovoid bodies, placed between the fibrous and
muscular coats, each furnished with an excretory duct, which opens 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 connecting the rings,
and others immediately beneath the mucous coat. The secretion from these glands
serves to lubricate the inner surface of the trachea.
Vessels and Nerves. The trachea is supplied with blood by the inferior thyroid
arteries. The veins terminate in the thyroid venous plexus. The nerves are
derived from the pneumogastric and its recurrent branches, and from the sympa-
thetic.
Surgical Anatomy. The air-passage may be opened in three different situations ; through the
crico-thyroid membrane (laryngotomy), through the cricoid cartilage and upper ring of the
trachea (laryngo4racheotomy), or through the trachea below the isthmus of the thyroid gland
(tracheotomy). The student should, therefore, carefully consider the relative anatomy of the
air-tube in each of these situations.
Beneath the integument of the laryngo-tracheal region, on either side of the median line, are
the two anterior jugular veins. Their size and position vary; there is nearly always one, and
frequently two : at the lower part of the neck they diverge, passing beneath the Sterno-mastoid
muscles, and are frequently connected by a transverse communicating branch. These veins
should, if possible, always be avoided in any operation on- the larynx or trachea. If cut through,
considerable hemorrhage is the result.
Beneath the cervical fascia are the Sterno-hyoid and Sterno-thyroid muscles, the contiguous
edges of the former being near the median line, and beneath these muscles the following parts
are met with, from above downwards ; the thyroid cartilage, the crico-thyroid membrane, the
cricoid cartilage, the trachea, and the isthmus of the thyroid gland.
The crico-thyroid space is very superficial, and may be easily felt, beneath the skin, as a
depressed spot, about an inch below the pomum Adami : it is crossed transversely by a small
artery, the crico-thyroid, the division of which is seldom accompanied by any troublesome
hemorrhage.
The isthmus of the thyroid gland usually crosses the second and third rings of the trachea ;
above it, is found a large transverse communicating branch between the superior thyroid veins,
and the isthmus is covered by a venous plexus, formed between the thyroid veins of opposite
sides. On the sides of the thyroid gland, and below it, the veins converge to a single median
vessel, or to two trunks which descend along the median line of the front of the trachea, to open
into the innominate veins by valved orifices. In the infant, the thymus gland ascends a variable
distance along the front of the trachea ; and the innominate artery crosses this tube obliquely at
the root of the neck, from left to right. The arteria thyroidea ima, when that vessel exists,
passes from below upwards along the front of the trachea. The upper part of the trachea lies
comparatively superficial ; but the lower part passes obliquely downwards and backwards, so as
to be deeply placed between the converging Sterno-mastoid muscles. In the child, the trachea
714
ORGANS OF VOICE AND RESPIRATION.
is smaller, more deeply placed, and more movable than in the 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 the opposite conditions.
Fig. 363.— Surgical Anatomy of Laryngotracheal Region
in the Infant.
Cvioo-ikyroid Minnln
le Artery
Cricoid CartUagt
&uj>eriar 2'Ayroul vein
From these observations, it must be evident that laryngotomy is anatomically the most simple
opei'ation, can most readily be performed, and should always be preferred when particular
circumstances do not render the operation of tracheotomy absolutely necessary. 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 the crico-thyroid membrane is
divided to a sufficient extent to allow of the introduction of a large curved tube. The crico-
thyroid artery is the only vessel of importance crossing this space. If it should be of large size,
its division might produce troublesome hemorrhage.
Laryngo-tracheotomy, anatomatically considered, is more dangerous than tracheotomy, on
account of the small interspace between the cricoid cartilage and the isthmus of the thyroid
gland ; the communicating branches between the superior thyroid veins, which cover this spot,
can hardly fail to be divided, and the greatest care will not, in some cases, prevent the division
of part of the thyroid isthmus. If either of these structures is divided, the hemorrhage will be
considerable.
Tracheotomy below the isthmus of the thyroid gland is performed thus : The head being
thrown back and steadied by an assistant, an incision, an inch and a half or two inches in
length, is made through the skin, in the median line of the neck, from a little below the cricoid
cartilage, to the top of the sternum. The anterior jugular veins should be avoided, by keeping
exactly in the median line ; the deep fascia should then be divided, and the contiguous
borders of the Sterno-hyoid muscles separated from each other. A quantity of loose areolar
tissue, containing the inferior thyroid veins, must then be separated from the front of the
trachea, with the handle of the scalpel ; and when the trachea is well exposed, it should be
opened by inserting the knife into it, dividing two or three of its rings from below upwards. It
is a matter of the greatest importance to restrain, if possible, all hemorrhage before the tube is
opened ; otherwise, blood may pass into the trachea, and suffocate the patient.
THE PLEURA.
U5
The Pleura.
Each lung is invested, upon its external surface, by an exceedingly delicate
serous membrane, the pleura, which incloses the organ as far as its root, and is
then reflected upon the inner surface of the thorax. The portion of the serous
Fig. 364.— A Transverse Section of the Thorax, showing the Relative Position of the Viscera,
and the Rellections of the Pleurae.
TRIANGULARIS STCR
luttrnaL JiLunmary Vessels
Ltft Phrt'tie Ittrv*
Plcuf^i fiulmonat**
Pleura CoduUis
Mediastinum-
Posterior
membrane investing the surface of the lung is called the -pleura pulmonalis
(visceral layer of pleura), whilst that which lines the inner surface of the chest
is called the pleura costalis (parietal layer of pleura). The interspace or cavity
between these two layers is called the cavity of the pleura. Each pleura is
therefore a shut sac, one occupying the right, the other the left half of the
thorax; and they are perfectly separate, not communicating with each other. The
two pleurae- do not meet in the middle line of the chest, excepting at one point in
front ; an interspace being left between them, which contains all the viscera of the
thorax, excepting the lungs : this is the mediastinum.
Reflections of the pleura (fig. 364). Commencing at the sternum, the pleura
passes outwards, covers the costal cartilages, the inner surface of the ribs and
Intercostal muscles, and at the back of the thorax passes over the thoracic
ganglia and their branches, and is reflected upon the sides of the bodies of the
vertebras, where it is separated by a narrow interspace from the opposite pleura,
the posterior mediastinum. From the vertebral column, the pleura passes to the
side of the pericardium, which it covers to a slight extent ; it then covers the
back part of the root of the lung, from the lower border of which a triangular
fold descends vertically by the side of the posterior mediastinum to the Diaphragm.
This fold is the broad ligament of the lung, the ligamentum latum pulmonis, and
serves to retain the lower part of the organ in position. From the root, the
716 ORGANS OF VOICE AND RESPIRATION".
pleura may be traced over the convex surface of the lung, the summit and base,
and also over the sides of the fissures between the lobes. It covers its anterioi'
surface, and front part of its root, and is reflected upon the side of the pericar-
dium to the .;'Pncr- surface of the sternum. Below, it covers the upper surface of
the Diaphragm. Above, its apex projects, in the form of a cul-de-sac, through the
superior opening of the thorax into the neck, extending about an inch above the
margin of the first rib, and receives the summit of the corresponding lung ; this
sac is strengthened, according to Dr. Sibson, by a dome-like expansion of fascia,
derived from the lower part of the Scaleni muscles.
A little above the middle of the sternum, the contiguous surfaces of the
two pleurae are in contact for a slight extent ; but, above and below this point,
the interval left between them by their non-approximation forms the anterior
mediastinum.
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.
Vessels and Nerves. The arteries of the pleura are derived from the intercostal,
the internal mammary, the phrenic, inferior thyroid, thymic, pericardiac, and
bronchial. The veins correspond to the arteries. The lymphatics are very
numerous. The nerves are derived from the phrenic and sympathetic (Luschka).
Kolliker states that nerves accompany the ramifications of the bronchial arteries
in the pleura pulmonalis.
Mediastinum.
The Mediastinum is the space left in the median line of the chest by the non-
approximation of the two pleurae. It extends from the sternum in front to the
spine behind, and contains all the viscera in the thorax, excepting the lungs.
The mediastinum may be subdivided, for convenience of description, into the
anterior, middle, and posterior.
The anterior mediastinum is bounded in front by the sternum, on each side by
the pleura, and behind by the pericardium. Owing to the oblique position of the
heart towards the left side, this space is not parallel with the sternum, but directed
obliquely from above downwards, and to the left of the median line ; it is broad
oelow, narrow above, very narrow opposite the second piece of the sternum, the
contiguous surfaces of the two pleurae being occasionally united over a small
space. The anterior mediastinum contains the origins of the Sterno-hyoid and
Sterno-thyroid muscles, the Triangularis sterni, the internal mammary vessels of
the left side, the remains of the thymus gland, and a quantity of loose areolar
tissue, containing some lymphatic vessels ascending from the convex surface of
the liver.
The middle mediastinum is the broadest part of the interpleural space. It
contains the heart inclosed in the pericardium, the ascending aorta, the superior
vena cava, the bifurcation of the trachea, the pulmonary arteries and veins, and
the phrenic nerves.
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 vertebral column, and on either side by the pleura. It
contains the descending aorta, the greater and lesser azygos veins and superior
intercostal vein, the pneumogastric and splanchnic nerves, the oesophagus, thoracic
duct, and some lymphatic glands.
THE LUNGS.
717
The Lungs.
The Lungs are the essential organs of respiration ; they are two in number,
placed one in each of the lateral cavities of the chest, separated from each other
by the heart and other contents of the mediastinum. Each lung is conical in
shape, and presents for examination an apex, a base, two borders, and twc
surfaces.
The apex forms a tapering cone, which extends into the root of the neck, about
an inch to an inch and a half above the level of the first rib.
Fig. 365. — Front View of the Thorax. The Ribs and Sternum are represented
in Relation to the Lungs, Heart, and other Internal Organs.
The lose is broad, concave, and rests upon the convex surface of the Dia-
phragm; its circumference is thin, and fits into the space between the lower ribs
and the costal attachment of the Diaphragm, extending lower down externally
and behind than in front.
The external or thoracic surface is smooth, convex, of considerable extent,
and corresponds to the form of the cavity of the chest, being deeper behind than
in front.
The inner surface is concave. It presents, in front, a depression corresponding
to the convex surface of the pericardium, and, behind, a deep fissure, the hilum
pulmonis, which gives attachment to the root of the lung.
718
ORGANS OF VOICE AND RESPIRATION
The posterior border is rounded and broad, and is received in the deep con-
cavity on either side of the spinal column. It is much longer than the anterior
border, and projects below between the ribs and Diaphragm.
The anterior border is thin and sharp, and overlaps the front of the peri-
cardium.
The anterior border of the right lung corresponds to the median line of the
sternum, and is in contact with its fellow, the pleuras being interposed, as low as
the fourth costal cartilage ; below this, the contiguous borders are separated by an
irregularly-shaped interval, formed at the expense of the anterior border of the
left lung, and corresponding to which the pericardium is exposed.
Fig. 306. — Front View of the Heart and Lungs.
Ductus Arter/orum
Each lung is divided into two lobes, an upper and lower, by a long and deep
fissure, which extends from the upper part of the posterior border of the organ,
about three inches from its apex, downwards and forwards to the lower part of
its anterior border. This fissure penetrates nearly to the root. In the right lung
the upper lobe is partially divided by a second and shorter fissure, which extends
from the middle of the preceding, forwards and upwards, to the anterior margin of
the organ, marking off a small triangular portion, the middle lobe.
The right lung is the largest ; it is broader than the left, owing to the inclination
of the heart to the left side, and is also shorter by an inch, in consequence of the
Diaphragm rising higher on the right side to accommodate the liver. The right
lung has also three lobes.
The left lung is smaller, narrower, and longer than the right, and has only two
lobes. . .
THE LUNGS. 719
A little above the middle of the inner surface of each lung, and nearer its pos-
terior than its anterior border, is its root, by which the lung is connected to the
heart and the trachea. It 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 inclosed
by a reflection of the pleura. The root of the right lung lies behind the superior
cava and upper part of the right auricle, and below the vena azygos. That 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 pneumogastric and posterior pulmonary plexus behind each.
The structures composing the root of each lung are arranged in a similar
manner from before backwards on both sides, viz. ; — the pulmonary veins most
anterior, the pulmonary artery in the middle, and the bronchus, together with
the bronchial vessels, behind. From above downwards, on the two sides, their
arrangement differs, thus: —
On the right side, their position is, bronchus, pulmonary artery, pulmonary
veins; on the left side, their position is, pulmonary artery, bronchus, pulmonary
veins : this is accounted for by the bronchus being placed on a lower level on
the left than on the right side.
The weight of both lungs together is about forty-two ounces, the right lung
being two 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, their proportion to the body being, in the former,
as 1 to 37, in the latter as 1 to 43. The specific gravity of the lung tissue varies
from 345 to 746, water being 1000.
The color of the lungs at birth is of a pinkish white; in adult life, mottled in
patches, of a dark slate color ; and, as age advances, this mottling assumes a
dark 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 border of the lung is usually darker than the anterior.
The surface of the lung is smooth, shining, and marked out into numerous poly-
hedral spaces, which represent the lobules of the organ, and 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.
Structure. The lungs are composed of an external serous coat, a subserous
areolar tissue, and the pulmonary substance or parenchyma.
The serous coat is derived from the pleura; it is thin, transparent, and invests
the entire organ as far as the root.
The subserous areolar tissue contains a large proportion of elastic fibres ; it
invests the entire surface of the lung, and extends inwards between the lobules.
The "parenchyma is composed of lobules, which, although closely connected
together by an interlobular areolar tissue, are quite distinct from one another,
being easily separable in the foetus. The lobules vary in size : those on the surface
are large, of a pyramidal form, the base turned towards the surface ; those in the
interior are smaller, and of various forms. Each lobule is composed of one of the
ramifications of the bronchial tube and its terminal air-cells, of the ramifications
of the pulmonary and bronchial vessels, lymphatics, and nerves; all of these
structures being connected together by areolar fibrous tissue.
The bronchus, upon entering the substance of the lung, divides and subdivides
dichotomously throughout the entire organ. Sometimes three branches arise
together, and occasionally small lateral branches are given off from the sides of a
main trunk. Each of the smaller subdivisions of the bronchi enters a pulmonary
720 ORGANS OF VOICE AND RESPIRATION.
lobule (lobular bronchial tube), and, again subdividing, ultimately terminates in
the intercellular passages and air-cells of which the lobule is composed. Within
the lungs the bronchial tubes are circular, not flattened, and their constituent
elements present the following peculiarities of structure.
The cartilages are not imperfect rings, but consist of thin laminaa, 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 dia-
meter of which is only one-fourth of a line. Beyond this point, the tubes are
wholly membranous. The fibrous coat and longitudinal elastic fibres are con-
tinued into the smallest ramifications of the bronchi. The muscular coat is dis-
posed in the form of a continuous layer of annular fibres, which may be traced
upon the smallest bronchial tubes ; they consist of the unstriped variety of muscular
fibre. The mucous membrane lines the bronchi and its ramifications throughout,
and is covered with columnar ciliated epithelium.
According to the observations of Mr. Rainey,1 the lobular bronchial tubes, on
entering the substance of the lobules, divide and subdivide from four to nine times,
according to the size of the lobule, continuing to diminish in size until they attain
a diameter of ^th to ^Dth of an inch. They then become changed in structure,
losing their cylindrical form, and are continued onwards as irregular passages
(intercellular passages), through the substance of the lobule, their sides and ex-
tremities being closely covered by numerous saccular dilatations, the air-cells.
This arrangement resembles most closely the naked eye appearances observed in
the reticulated structure of the lung of the tortoise, and other reptilia.
The air-cells are small, polyhedral, alveolar recesses, separated from each other
by thin septa, and communicating freely with the intercellular passages. They
are well seen on the surface of the lung, and vary from 5^th to ^th of an inch
in diameter, being largest on the surface, at the thin borders, and at the apex,
and smallest in the interior.
At the termination of the bronchial tubes, in the intercellular passages, their
constituent elements become changed ; their walls are formed by an interlacing of
the longitudinal elastic bundles with fibrous tissue, the muscular fibres disappear,
and the mucous membrane becomes thin and delicate, and lined with a layer of
squamous epithelium. The latter membrane lines the air-cells, and forms by its
reduplications the septa intervening between them.
The Pulmonary Artery 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 intercellular passages and air-cells. From this
network, the radicles of the pulmonary veins arise ; coalescing into large branches,
they accompany the arteries, and return the blood, purified by its passage
through the capillaries, to the left auricle of the heart. 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, on the walls and septa of the air-cells, and upon the walls of
the intercellular passages. In the septa between the cells, the capillary network
forms a single layer. The capillaries are very minute, the meshes being only
slightly wider than the vessels ; their walls are also exceedingly thin.
The Bronchial Arteries supply blood for the nutrition of the lung ; they are
derived from the thoracic aorta, and, accompanying the bronchial tubes, are dis-
tributed to the bronchial glands, and upon the walls of the larger bronchial tubes
and pulmonary vessels, and terminate- in the deep bronchial veins. Others are
distributed in the interlobular areolar tissue, and terminate partly in the dee]),
partly in the superficial, bronchial veins. Lastly, some ramify upon the walls of
the smallest bronchial tubes, and terminate in the pulmonary veins.
The Superficial and Deep Bronchial Veins unite at the root of the lung, and
1 Medico-Chirurgical Transactions, vol. xxviii. 1845.
THYROID GLAND. 121
terminate oi\ the right side in the vena azygos ; on the left side, in the superior
intercostal vein.
The Lymphatics consist of a superficial and deep set ; they terminate at the root
of the lung, in the bronchial glands.
Nerves. The lungs are supplied from the anterior and posterior pulmonary
plexuses, formed chiefly by branches from the sympathetic and pneumogastric.
The filaments from these plexuses accompany the bronchial tubes upon which they
are lost. Small ganglia have been found by Eemak upon the smaller branches of
these nerves.
Thyroid Gland.
The Thyroid Gland bears much resemblance in structure to other glandular
organs, and is usually classified together with the thymus, supra-renal glands, and
spleen, under the head of ductless glands, from its possessing no excretory duct.
Its function is unknown, but, from its situation in connection with the trachea
and larynx, is usually described with these, although taking no part in the
function of respiration. It is situated at the upper part of the trachea, and
consists of two lateral lobes, placed one on each side of this tube, connected
together by a narrow transverse portion, the isthmus.
Its anterior surface is convex, and covered by the Sterno-hyoid, Sterno-thyroid,
and Omo-hyoid muscles.
Its lateral surfaces, also convex, lie in contact with the sheath of the common
carotid artery.
Its posterior surface is concave, and embraces the trachea and larynx. The
posterior borders of the gland extend as far back as the lower part of the
pharynx.
This gland is of a brownish-red color. Its weight varies from one to two
ounces. It is larger in females than in males, and becomes slightly increased in
size during menstruation. It occasionally becomes enormously hj'pertrophied, con-
stituting the disease called bronchocele or goitre. Each lobe is somewhat conical
in shape, about two inches in length, and three-quarters of an inch in breadth, the
right lobe being rather the larger of the two.
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. Its situation presents, however, many variations, a
point of some importance in the operation of tracheotomy. Sometimes the isthmus
is altogether wanting.
A third lobe, of conical shape, called the pyramid, occasionally arises from the
left side of the upper part of the isthmus, or from the left lobe, and ascends as
high as the hyoid bone. It is occasionally quite detached, or divided into two
parts, or altogether wanting.
A few muscular bands 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
were named by Soemmering, the Levator rjlandulve tltyroideve.
Structure. The thyroid consists of numerous minute closed vesicles, com-
posed of a homogeneous membrane, inclosed in a dense capillary plexus, and
connected together into imperfect lobules by areolar tissue. These vesicles are
spherical or oblong, perfectly distinct, and contain a yellowish fluid, in which
are found floating numerous "dotted corpuscles" and cells. The fluid coa-
gulates by heat or alcohol, but preserves its transparency. In the foetus
and in young subjects, the corpuscles lie in a single layer, in contact with
the inner surface of these cavities, and become detached during the process of
growth.
Vessels and Nerves. The arteries supplying the thyroid are the superior and
inferior thyroid, and sometimes an additional branch from the arteria innominata,
which ascends from this vessel upon the front of the trachea. The arteries arc
46
722 ORGANS OF YOICE AND RESPIRATION.
remarkable for their large size and frequent anastomoses. The veins form a
plexus on the surface of the gland, and on the front of the trachea, from which
arise the superior, middle, and inferior thyroid veins ; the two former terminating
in the internal jugular, the latter in the vena innominata. The lymphatics are
numerous, of large size, and terminate in the thoracic and right lymphatic ducts.
The nerves are derived from the pneumogastric, and from the middle and inferior
cervical ganglia of the sympathetic.
Chemical Composition. The thyroid gland consists of albumen, traces of gela-
tin, stearin, olein, extractive matter, alkaline and earthy salts, and water. The
salts are chloride of sodium, alkaline sulphate, phosphate of potash, lime, mag-
nesia, and a trace of oxide of iron.
Thymus Gland.
The Thymus Gland presents much resemblance in structure to other glandular
organs, and is classified under the head of the ductless glands, from its possessing
no excretory duct.
The thymus gland is a temporary organ, attaining its full size at the end of the
second year, when it ceases to grow, and gradually dwindles, until, at puberty, it
has almost disappeared. If examined when its growth is most active, it will be
found to consist of two lateral lobes, placed in close contact along the middle line,
situated partly in the anterior mediastinum, partly in the neck, and extending
from the fourth costal cartilage upwards, 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. In the mediastinum, it rests upon the pericardium,
being separated from the arch of the aorta and great vessels, by the thoracic
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 occasionally united so as to form a single mass, and sometimes
separated by an intermediate lobe. The thymus is of a pinkish-gray color, soft,
and lobulated on its surfaces. It is about two inches in length, one and a half in
breadth, below, and about three or four lines in thickness. At birth, it weighs
about half an ounce.
Structure. Each lateral lobe is composed of numerous lobules, held together by
delicate areolar tissue, the entire gland being inclosed 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. Each lobule contains, in its interior, a small cavity, which
is surrounded with smaller or secondary lobules, which are also hollow within.
The cavities of the secondary and primary lobules communicate ; those of the
latter opening into the great central cavity or reservoir of the thymus, which
extends through the entire length of each lateral half of the gland. The central
cavity is lined by a vascular membrane, which is prolonged into all the subordinate
cavities, and contains a milk-white fluid resembling chyle.
If the investing capsule and vessels, as well as the areolar tissue connecting
the lobules, are removed from the surface of either lateral lobe, it will be seen
that the •central cavity is folded upon itself, and admits of being drawn out into a
lengthened tubular cord, around which the primary lobules are attached in a
spiral manner, like knots upon a rope. Such is the condition of the organ at an
early period of its development ; for Mr. Simon has shown, that the primitive
form of the thymus is a linear tube, from which, as its development proceeds,
lateral diverticula lead outwards, the tube ultimately becoming obscure, from its
surface being covered with numerous lobules.
According to Oesterlen and Mr. Simon, the cavities in the secondary lobules
are surrounded by rounded saccular dilatations or vesicles, which open into it.
These vesicles are formed of a homogeneous membrane, inclosed in a dense capil-
lary plexus.
The whitish fluid contained in the vesicles and central cavity of the thymus
THYMUS GLAND. 723
contains numerous dotted corpuscles, similar to those found in the chyle. The
corpuscles are flattened circular disks, measuring about TTyW of an inch in dia-
meter.
Vessels and Nerves. The arteries supplying the thymus are derived from the
internal mammary, and from the superior and inferior thyroid. The veins termi-
nate in the left vena innominata, and in 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. Sir A. Cooper considered that these vessels carried into
the blood the secretion formed in the substance of the thymus. The nerves are
exceedingly minute ; they are derived from the pneumogastric and sympathetic.
Branches from the descendens noni and phrenic reach the investing capsule, but
do not penetrate into the substance of the gland.
Chemical Composition. The solid animal constituents of the thymus are albu-
men and fibrin in large quantities, gelatin and other animal matters. The salts
are alkaline and earthy phosphates, with chloride of potassium. It contains about
80 per cent, of water.
The Urinary Organs.
The Kidneys.
The Kidneys are two glandular organs, intended for the secretion of the urine.
They are situated at the back part of the abdominal cavity, behind the peri-
toneum, one in each lumbar region, extending from the eleventh rib to near the
crest of the ilium; the right one being lower than the left, from its vicinity to
the liver. They are usually surrounded by a considerable quantity of fat, and
are retained in their position by the vessels which pass to and from them.
Relations. The anterior surface of the kidney is convex, partially covered by
the peritoneum, and is in relation, on the right side, with the back part of the
right lobe of the liver, the descending portion of the duodenum, and ascending
colon ; and on the left side with the great end of the stomach, the lower end of the
spleen, the tail of the pancreas, and the descending colon.
The posterior surface is flattened, and rests upon the corresponding crus of the
Diaphragm, in front of the eleventh and twelfth ribs, on the anterior lamella of
the aponeurosis of the Transversalis which separates it from the Quadratus lum-
borum, and on the Psoas magnus.
The superior extremity, directed inwards, is thick and rounded, and embraced
by the supra-renal capsule. It corresponds, on the left side, to the upper border
of the eleventh rib, and on the right side to the lower border.
The inferior extremity, small and flattened, extends nearly as low as the crest
of the ilium.
The external border is convex, and directed outwards towards the parietes of
the abdomen.
The internal border is concave, and presents a deep notch, the hilus of the kidney,
more marked behind than in front. At the hilus, the vessels, excretory duct,
and nerves pass into or from the organ ; the branches of the renal vein lying in
front, the artery and its branches next, the excretory duct or ureter being behind
and below. On the vessels the nerves and lymphatics ramify, and much cellular
tissue and fat surrounds the whole. The hilus leads into a hollow space, the
sinus, which occupies the interior of the gland.
Each kidney is about four inches in length, two inches in breadth, and about
one inch in thickness ; the left one being somewhat longer and thinner than the
right. The weight of the kidney in the adult male varies from 4J oz. to 6 oz. ;
in the female, from 4 oz. to 5| oz., the difference between the two being about
half an ounce. The left is nearly always heavier than the right, by about two
drachms. Their weight in proportion to the body is about 1 to 240. The renal
substance is dense, firm, extremely fragile, and of a deep red color.
The kidney is invested by a fibrous capsule, formed of dense fibro-areolar
tissue. It is thin, smooth, and easily removed from its surface, to which it is con-
nected by fine fibrous processes and vessels ; and at the hilus is continued inwards,
lining the sides of the sinus, and at the bottom of that cavity forms sheaths around
the bloodvessels and the subdivisions of the excretory duct.
On making a vertical section through the organ, from its convex to its concave
border, it appears to consist of two different substances, viz., an external or cor-
tical, and an internal or medullary, substance.
The cortical substance forms about three-fourths of the gland. It occupies the
724
THE KIDNEYS.
725
Fig. 367. — Vertical Section of Kidney,
surface of the kidney, forming a layer about two lines in thickness, where it covers
the pyramids, and sends numerous prolongations inwards, towards the sinus between
the pyramids.
The cortical substance is soft, reddish,
granular, easily lacerated, and contains nu-
merous small red bodies disseminated through
it in every part, excepting towards the free
surface. These are the Malpighian bodies.
The cortical substance is composed of a mass
of convoluted tubuli uriniferi, bloodvessels,
lymphatics, and nerves, connected together
by a firm, transparent, granular substance,
which contains small granular cells.
The medullary substance consists of pale,
reddish-colored, conical masses, the pyra-
mids of Malpighi, varying in number from
eight to eighteen; their bases are directed
towards the circumference of the organ,
whilst their apices, which are free from the
cortical substance, converge towards the
sinus, and terminate in smooth, rounded ex-
tremities, called the papillse (mammillae) of
the kidney. Sometimes, two of the masses
are joined, and have between them only one
papilla. The kidney is thus seen to consist
of a number of conical-shaped masses, each
inclosed, excepting at the apex, by an invest-
ment of the cortical substance ; these repre-
sent the separate lobules of which the human
kidney in the foetus consists, a condition
observed permanently in the kidneys of many of the lower animals. - As the
human kidney becomes developed, the adjacent lobules coalesce, so as to form a
single gland, the surface of which, even in the adult, occasionally presents faint
traces of a lobular subdivision.
The medullary substance is denser in structure than the cortical, darker in color,
and presents a striated appearance, from being composed of a number of minute
diverging tubes (tubuli uriniferi). The tubuli uriniferi commence at the apices of
the cones by small orifices, which vary from
3tf?y to 2£ff of an inch; as they pass up in
the medullary substance, towards the peri-
phery, they pursue a diverging course, di-
viding and subdividing at very acute angles,
until they reach the cortical substance, when
they become convoluted, anastomose freely
with each other, and retain the same diameter.
The number of orifices on the entire surface
of a single papilla is, according to Huschke,
about a thousand ; from four to five hundred
large, and as many smaller ones. The tubuli
uriniferi are formed of a transparent homo-
geneous basement membrane, lined by sphe-
roidal epithelium, which occupies about two-
thirds of the diameter of the tube. The
tubes are separated from one another, in the
medullury cones, by capillary vessels, which form oblong meshes parallel with the
tubuli, and by an intermediate parenchymatous substance composed of cells.
As soon as the tubuli uriniferi enter the cortical substance (fig. 368), they
Fig. 368. — Minute Structure of Kidney.
>i"t#
726 URINARY ORGANS.
become convoluted, and anastomose freely with each other ; they are sometimes
called the tubes of Ferrein. At the bases of the pyramids, the straight tubes are
described as being collected into small conical bundles, the tortuous tubuli cor-
responding to which are prolonged upwards into the cortical portion of the kidney
as far as the surface, forming a number of small conical masses, which are named
the pyramids of Ferrein, several of which correspond to each medullary cone and
its corresponding portion of cortical substance. According to Mr. Bowman, the
tubuli uriniferi commence in the cortical substance as small, dilated, membranous
capsules, the capsules of the Malpighian bodies ; they also form loops, either by the
junction of adjacent tubes, or, according to Toynbee, by the union of two branches
proceeding from the same tube ; they have also been seen to arise by free closed
extremities.
The Malpighian bodies are found only in the cortical substance of the kidney.
They are small round bodies, of a deep red color, and of the average diameter
of the yl^ of an inch. Each body is composed of a vascular tuft inclosed in a
thin membranous capsule, the dilated commencement of a uriniferous tubule. The
vascular tuft consists of the ramifications Of a minute artery, the afferent vessel,
which, after piercing the capsule, divides, in a radiated manner, into several
branches, which ultimately terminate in a finer set of capillary vessels. From
these, a small vein, the efferent vessel, proceeds ; this pierces the capsule near the
artery, and forms a close venous plexus, with the efferent vessels from other
Malpighian bodies, round the adjacent tubuli.
The capsular dilatation of the Malpighian body is not always placed at the
commencement of the tube ; it may occupy one side (Gerlach) : hence their sub-
division into lateral or terminal. The membrane composing it is thicker than that
of the tubule ; the epithelium lining its inner surface is thin, and, in the frog,
provided with ciliae at the neck of the dilated portion ; but in the human subject,
ciliae have not been detected. According to Mr. Bowman, the surface of the
vascular tuft lies free and uncovered in the interior of its capsule ; but, according
to Gerlach, it is covered with a thick layer of nucleated cells, similar to those
lining the inner surface of the capsule.
Ducts. The ureter, as it approaches the hilus, becomes dilated into a funnel-
shaped membranous sac, the pelvis. It then enters the sinus, and subdivides
usually into three prolongations, the infundibula, one placed at each extremity,
and one in the middle of the organ ; these subdivide into from seven to thirteen
smaller tubes, the calyces, each of which embraces, like a cup-like pouch or calyx,
the base of one of the papillae. Sometimes, a calyx incloses two or more papillae.
The ureter, the pelvis, and the calyces consist of three coats, — fibrous, muscular,
and mucous.
The external or fibro-elastic coat is continuous, round the bases of the papillae,
with the tunica propria investing the surface of the organ.
The muscular coat is placed between the fibrous and mucous coats. It consists
of an external or longitudinal, and an internal or circular stratum.
The internal or mucous coat invests the papillae of the kidney, and is continued
into the orifices upon their surfaces. It is lined by epithelium of the spheroidal
kind.
Vessels, and Nerves. The renal artery is large in proportion to the size of
the organ which it supplies. Each vessel divides into four or five branches,
which enter the hilus, and are invested by sheaths derived from the fibrous capsule ;
they penetrate the substance of the organ between the papillae, and enter the
cortical substance in the intervals between the medullary cones, dividing and
subdividing in their course towards the bases of the pyramids, where they form
arches by their anastomoses ; from these arches, numerous vessels are distributed
to the cortical substance, some of which enter the Malpighian corpuscles, whilst
others form a capillary network round the uriniferous tubes.
The veins of the kidney commence upon the surface of the organ, where they
have a stellate arrangement ; they pass inwards, and open into larger veins, which
URETERS — SUPRA-RENAL CAPSULES. 727
unite into arches round the bases of the medullary cones. After receiving the
venous plexus from the tubular portion, they accompany the branches of the
arteries to the sinus of the kidney, where they finally unite to form a single vein,
which terminates in the inferior vena cava.
The lymphatics of the kidney consist of a superficial and deep set ; they accom-
pany the bloodvessels, and terminate in the lumbar glands.
The nerves are derived from the renal plexus, which is formed by filaments
from the solar plexus and lesser splanchnic nerve ; they accompany the branches
of the arteries. From the renal plexus, some filaments pass to the spermatic-
plexus and ureter.
The Ureters.
The Ureter is the excretory duct of the kidney. It is a cylindrical mem-
branous tube, from sixteen to eighteen inches in length, and of the diameter of a
goose-quill. It is placed at the back part of the abdomen, behind the peritoneum ;
and extends obliquely downwards and inwards, from the lower part of the pelvis
of the kidney, enters the cavity of the pelvis, and then passes downwards, for-
wards, and inwards, to the base of the bladder, into which it opens by a con-
stricted orifice, after passing obliquely, for nearly an inch, between its muscular
and mucous coats.
Relations. In its course from above downwards, it rests upon the Psoas
muscle, being covered by the peritoneum, and crossed in front very obliquely by
the spermatic vessels ; the right ureter lying close to the outer side of the inferior
vena cava. Opposite the sacrum, it crosses the common or the external iliac
artery, lying behind the ileum on the right side, and the sigmoid flexure of the
colon on the left. In the pelvis, it enters the posterior false ligament of the
bladder, and runs below the obliterated hypogastric artery, the vas deferens, in
the male, passing between it and the bladder. In the female, the ureter passes
along the sides of the cervix uteri and upper part of the vagina. At the base of
the bladder, it is situated about two inches from its fellow ; lying, in the male,
about an inch and a half behind the base of the prostate, at the posterior angle of
the trigone.
Structure. The ureter is composed of three coats, fibrous, muscular, and
mucous.
The fibrous coat is continuous with that surrounding the pelvis.
The muscular coat consists of two layers of longitudinal fibres, and an inter-
mediate transverse layer.
The mucous coat is smooth, and presents a few longitudinal folds, which
become effaced by distension. It is continuous with the mucous membrane of the
bladder below ; whilst, above, it is prolonged over the papillae into the tubuli
uriniferi. The epithelial cells lining it are spheroidal.
The arteries supplying the ureter are branches of the renal, spermatic, internal
iliac, and inferior vesical.
The nerves are derived from the inferior mesenteric, spermatic, and hypo-
gastric plexuses.
Supra-renal Capsules.
The Supra-renal Capsules are usually classified, together with the spleen,
thymus, and thyroid, under the head of "ductless glands," as they have no excre-
tory duct. They are two small flattened glandular bodies, of a yellowish color,
situated at the back part of the abdomen, behind the peritoneum, immediately in
front of the upper end of either kidney ; hence their name. The right one is
somewhat triangular in shape, bearing a resemblance to a cocked hat ; the left is
more semilunar, and usually larger and higher than the right. They vary in size
in different individuals, being sometimes so small as to be scarcely detected, at
other times large. They measure from *>n inch and a quarter to nearly two
728 URINARY ORGANS.
inches in length, are rather less in width, and from two to three lines in thickness.
In weight, they vary from one to two drachms.
Relations. The anterior surface of the right supra-renal capsule is in relation
with the under surface of the liver ; that of the left with the pancreas and spleen.
The posterior surface rests upon the crus of the Diaphragm, opposite the tenth
dorsal vertebra. Their upper thin convex border is directed upwards and inwards.
Their lower thick concave bonier rests upon the upper end of the kidneys, to which
they are connected by areolar tissue. Their inner borders are in relation with the
great splanchnic nerves and semilunar ganglia, and lie in contact on the right side
with the inferior vena cava, and on the left side with the aorta. The surface of
the supra-renal 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 the numerous fibrous processes and vessels which enter the organ through the
furrows on its anterior surface and base.
Structure. On making a perpendicular section, the gland is seen to consist of
two substances, external or cortical, and internal or medullary.
The cortical substance forms the chief part of the organ ; it is of a deep yellow
color, andv consists of narrow columnar masses placed perpendicularly to the
surface.
The medullary substance is soft, pulpy, and of a dark brown or black color ;
hence the name, atrabiliary capsules, given to these organs. In its centre is often
seen a space formed by the breaking down of its component parts.
According to the researches of Oesterlen and Mr. Simon, the narrow columnar
masses of which the cortical substance is composed measure about T J ^th of an
inch in diameter, and consist of small closed parallel tubes of limitary membrane
containing dotted nuclei, together with much granular matter, oil globules, and
nucleated cells. According to Ecker, the apparent tubular canals consist of rows
of closed vesicles placed endwise, so as to resemble tubes ; whilst Kolliker states,
that these vesicles are merely loculi or spaces in the stroma of the organ, having
no limitary membrane, and, from being situated endwise, present the appearance
of linear tubes. Nucleated cells exist in large numbers in the supra-renal glands
of ruminants, but more sparingly in man and other animals, but the granular
matter appears to form their chief constituent; the granules vary in size, and they
present the singular peculiarity of undergoing no change when acted upon by
most of the chemical reagents. The columnar masses are surrounded by a close
capillary network, which runs parallel with them.
The medullary substance consists of nuclei and granular matter, uniformly
scattered throughout a plexus of minute veins.
The arteries supplying the supra-renal glands are numerous and of large size,
and 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 supra-renal vein returns the blood from the medullary venous plexus, and
receives several branches from the cortical substance ; it opens on the right side
into the inferior vena cava, on the left side into the renal vein.
The lymphatics terminate in the lumbar glands.
The nerves are exceedingly numerous; they are derived from the solar and renal
plexuses, and, according to Bergmann, from the phrenic and pneumogastric nerves.
They have numerous small ganglia developed upon them.
The Pelvis.
The Cavity of the Pelvis is that part of the general abdominal cavity which is
below the level of the linea ilio-pectinea and the promontory of the sacrum.
Boundaries. It is bounded, behind, by the sacrum, the coccyx, and the great
sacro-sciatic ligaments ; in front and at the sides, by the pubes and ischia, covered
by the Obturator muscles; above, it communicates with the cavity of the abdomen;
and below, it is limited by the Levatores ani and Coccygei muscles, and the
BLADDER.
729
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
lower end of the rectum, and some of the generative organs peculiar to each
sex ; they are partially covered by the peritoneum, and supplied with blood and
lymphatic vessels and nerves.
The Bladder.
The 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 uterus and vagina intervening between it and that intestine in the female.
The shape, position, and relations of the bladder are greatly influenced by age,
sex, and the degree of distension of the organ. During infancy, it is conical in
shape, and projects above the upper border of the pubes into the hypogastric
region. In the adult, when quite empty and contracted, it is a small triangular
Fig. 369. — Vertical Section of Bladder, Penis, and Urethra.
Covftr'k CI
Prtpuo*
sac, placed deeply in the pelvis, flattened from before backwards, its apex reaching
as high as the upper border of the symphysis pubis. When slightly distended, it
has a rounded form, and partially fills the pelvic cavity; when greatly distended it
is ovoid in shape, rising into the abdominal cavity, often extending upwards nearly
as high as the umbilicus. It is larger in its vertical diameter than from side to
side, and its long axis is directed from above obliquely downwards and backwards
in a line directed from some point between the pubes and umbilicus (according to
its distension) to the end of the coccyx. The bladder, when distended, is slightly
curved forwards towards the anterior wall of the abdomen, so as to be more
130 URINARY ORGANS.
convex behind than in front. In the female, it is larger in the transverse than
in the vertical diameter, and its capacity is said to be greater than in the male.
"When moderately distended, it measures about five inches in length, and three
inches across, and the ordinary amount which it contains is about a pint.
The bladder is divided into a summit, body, base, and neck.
The summit or apex of the bladder is rounded and directed forwards and
upwards ; it is connected to the umbilicus by a fibro-muscular cord, the urachus,
and also by means of two rounded fibrous cords, the obliterated portions of the
hypogastric arteries, which are placed one on each side of the urachus. The
summit of the bladder behind the urachus is covered by peritoneum, whilst the
portion in front is uncovered by it, and rests upon the abdominal wall.
The urachus is the obliterated remains of a tubular canal existing in the embryo,
which connects the cavity of the bladder with a membranous sac placed external
to the abdomen, opposite the umbilicus, called the allantois. In the infant at
birth, it is occasionally found pervious, so that the urine escapes at the umbilicus,
and calculi have been found in its canal.
The body of the bladder in front is not covered by peritoneum, and is in
relation with the triangular ligament of the urethra, the posterior surface of the
symphysis pubis, the Internal obturator muscles, and, when distended, with the
abdominal parietes.
The posterior surface is covered by peritoneum throughout. It corresponds,
in the male, with the rectum ; in the female, with the uterus, some convolutions of
the small intestine being interposed.
The side of the bladder is crossed obliquely from below, upwards and forwards,
by the obliterated hypogastric artery ; above and behind this cord, the bladder is
covered by peritoneum, but, below and in front of it, the serous covering is
wanting, and it is connected to the pelvic fascia. The vas deferens passes, in an
arched direction, from before backwards, along the side of the bladder, towards
its base, crossing in its course the obliterated hypogastric artery, and passing along
the inner side of the ureter.
The base or fundus of the bladder is directed downwards and backwards. It
varies in extent according to the state of distension of the organ, being very
broad when full, but much narrower when empty. In the male, it rests upon the
second portion of the rectum, from which it is separated by a reflection of the
recto- vesical fascia. It is covered posteriorly, for a slight extent, by the peri-
toneum, which is reflected from it upon the rectum, forming the recto-vesical fold.
The portion of the bladder in relation with the rectum corresponds to a triangular
space, bounded behind by the recto-vesical fold ; on either side, by the vesicula
seminalis and vas deferens; and, in front, by the prostate gland. 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 lies in contact with the lower part of the cervix uteri, is adherent
to the anterior wall of the vagina, and separated from the upper part of the
anterior surface of the cervix uteri by a fold of the peritoneum.
The cervix or neck of the bladder is the constricted portion continuous with
the urethra. In the male, its direction is oblique in the erect posture, and it is
surrounded by the prostate gland. In the female, its direction is obliquely down-
wards and forwards.
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 and two
lateral, formed by the recto-vesical fascia, and the urachus. The false ligaments,
also five in number, are formed by folds of the peritoneum.
The anterior ligaments (pubo-prostatic) extend from the back of the pubes, one
on each side of the symphysis, to the front of the neck of the bladder, and upper
surface of the prostate gland. These ligaments contain a few muscular fibres,
prolonged from the bladder.
STRICTURE OF THE BLADDER. 731
The lateral ligaments, broader and thinner than the preceding, are attached to
the lateral parts of the prostate, and to the sides of the base of the bladder.
The urachus is the fibro-muscular cord already mentioned, 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.
The false ligaments of the bladder are, two posterior, two lateral, and one
superior.
The two posterior pass forwards, in the male, from the sides of the rectum ; in
the female, from the sides of the uterus, to the posterior and lateral aspect of the
bladder : they form the lateral boundaries of the recto- vesical fold of peritoneum,
and contain the obliterated hypogastric arteries, the ureters, and vessels and
nerves.
The two lateral ligaments are reflections of the peritoneum, from the iliac fossae
to the sides of the bladder.
The superior ligament is the prominent fold of peritoneum extending from the
summit of the bladder to the umbilicus. It covers the urachus, and the obliterated
hypogastric arteries.
Structure. The bladder is composed of four coats : — a serous, a muscular, a cel-
lular, and a mucous coat.
The serous coat is partial, and derived from the peritoneum. It invests the
posterior surface, from opposite the termination of the two ureters to its summit,
and is reflected from this point and from the sides, on to the abdominal and pelvic
walls.
The muscular coat consists of two layers of unstriped muscular fibre, an
external layer, composed of longitudinal fibres, and an internal layer of circular
fibres.
The longitudinal fibres are most distinct on the anterior and posterior surfaces
of the organ. They arise, in front, from the anterior ligaments of the bladder,
from the neck of the bladder, and, in the male, from the adjacent portion of the
prostate gland. They spread out, and form a plexiform mesh, on the anterior
surface of the bladder, being continued over the posterior surface and base of
the organ to the neck, where they are inserted into the prostate in the male, and
into the vagina in the female.
Other longitudinal fibres arise, in the male, from the sides of the prostate, and
spread out upon the sides of the bladder, intersecting with one another.
The circular fibres are very thinly and irregularly scattered on the body of
the organ ; but, towards its lower part, round the cervix and commencement of the
urethra, they are disposed as a thick circular layer, forming the sphincter vesicae,
which is continuous with the muscular fibres of the prostate gland.
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 means of a
fibrous process, into the middle lobe of this organ. They are the muscles of the
ureters, described by Sir C. Bell, who supposed that, during the contraction of
the bladder, they served to retain the oblique direction of the ureters, and so
prevent the reflux of urine into them.
The cellular coat consists of a layer of areolar tissue, connecting together the
muscular and mucous coats, being intimately connected with the latter.
The mucous coat is thin, smooth, and of a pale rose color. It is continuous
through the ureters with the lining membrane of the uriniferous tubes, and, below,
with the urethra. It is connected loosely to the muscular coat, by a layer of
areolar tissue, excepting at the trigone, where its adhesion is more close. It is
provided with a few mucous tollicles, and numerous small racemose glands,
lined with columnar epithelium, exist near the neck of the organ. The epithe-
lium covering it is intermediate in form between the columnar and squamous
varieties.
Interior of the bladder. Upon the inner surface of the base of the bladder,
immediately behind the urethral orifice, is a triangular, smooth surface, the apex
T32
"URINARY ORGANS.
Fig. 370.— The Bladder and Urethra laid open.
Seen from above.
Cwp"'> Gl*
of which is directed forwards; this is the trigonum vesicse or trigone vesicale. It
's paler in color than the rest of the mucous membrane, and never presents any
rugae, even in the collapsed condition of the organ, owing to its intimate adhesion
to the subjacent tissues. It is bounded on each side by two slight ridges, which
pass backwards and outwards to the orifices of the ureters, and correspond with
the muscles of these tubes ; and at each posterior angle, by the orifices of the
ureters, which are placed nearly two inches from each other, and about an inch
and a half behind the orifice of the urethra. The trigone corresponds with the
interval at the base of the bladder,
bounded by the prostate in front, and
the vesicula3 and vasa deferentia on
the sides. Projecting from the lower
and anterior part of the bladder, into
the orifice of the urethra, is a slight
elevation of mucous membrane, called
the uvula vesicse. It is formed by a
thickening of the prostate.
The arteries supplying the bladder
are the superior, middle, and inferior
vesical, in the male, with additional
branches from the uterine, in the female.
They are all derived from the anterior
trunk of the internal iliac.
The veins form a complicated plexus
round the neck, sides, and base of the
bladder, and terminate in the internal
iliac veins.
The lymphatics accompany the
bloodvessels, passing through the
glands surrounding them.
The nerves are derived from the
hypogastric and sacral plexuses; the
former supplying the upper part of
the organ, the latter its base and
neck.
Male Urethra.
The Urethra extends from the neck
of the bladder to the meatus urinarius.
It is curved in its course, so as to
resemble, in its flaccid state, the Italic
letter /; but in the erect state it forms
only a single curve, the concavity of
which is directed upwards. 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 essentially different.
The Prostatic portion is the widest and most dilatable part of the canal. It
passes through the prostate gland, from its base to its apex, lying nearer its upper
than its lower surface. It is about an inch and a quarter in length, and the form
of the canal is spindle-shaped, being wider in the middle than at either extremity,
and narrowest in front, where it joins the membranous portion. A transverse
section of the canal in this situation is triangular, the apex directed downwards.
Upon the floor of the canal is a narrow longitudinal ridge, the veru montanum
Ottflcr* cf Juct*.
s/'Coitytrs Glands
URETHRA. 733
or caput yallinaginis, formed by an elevation of the mucous membrane and its.
subjacent tissue. It is eight or nine lines in length, and a line and a half in
height, and contains, according to Kobelt, muscular and erectile tissues. When
distended, it may serve to prevent the passage of the semen backwards into the
bladder. On each side of the veru montanum is a slightly depressed fossa, the
prostatic sinus, the floor of which is perforated by numerous apertures, the orifices
of the prostatic ducts, the ducts of the middle lobe opening behind the crest. At
the fore part of the veru montanum, in the middle line, is a depression, the sinus
pocularis or vesicula prostalica; and upon or within its margins are the slit-like
openings of the ejaculatory ducts. The sinus pocularis forms a cul-de-sac about
a quarter of an inch in length, which runs upwards and backwards in the sub-
stance of the prostate, beneath the middle lobe ; its prominent upper wall partly
forms the veru montanum. Its walls are composed of fibrous tissue, muscular
fibres, and mucous membrane ; and numerous small glands open on its inner sur-
face. It has been called by Weber, who discovered it, the uterus masculinus,
from its supposed homology with the female organ.
The Membranous portion of the urethra extends between the apex of the pros-
tate, and the bulb of the corpus spongiosum. It is the narrowest part of the canal
(excepting the orifice), and measures three-quarters of an inch along its upper,
and half an inch along its lower surface, in consequence of the bulb projecting
backwards beneath it below. Its upper concave surface is placed about an inch
beneath the pubic arch, from which it is separated by the dorsal vessels and nerves
of the penis, and some muscular fibres. Its lower convex surface is separated
from the rectum by a triangular space, which constitutes the perineum. The
membranous portion of the urethra perforates the deep perineal fascia ; and two
layers from this membrane are prolonged round it, the one forwards, the other
backwards ; it is also surrounded by the Compressor urethraa muscle. Its cover-
ings are mucous membrane, elastic fibrous tissue, a thin layer of erectile tissue,
muscular fibres, and a prolongation from the deep perineal fascia.
The Spongy portion is the longest part of the urethra, and is contained in the
corpus spongiosum. It is about six inches in length, and extends from the termi-
nation of the membranous portion to the meatus urinarius. Commencing below
the symphysis pubis, it ascends for a short distance, and then curves downwards.
It is narrow, and of uniform size in the body of the penis, measuring about a
quarter of an inch in diameter ; being dilated behind, within the bulb, where it
forms the bulbous portion, and again anteriorly, within the glans penis, forming
the fossa navicularis. A cross section of this canal in the body has its diameter
transverse, but in the glans the diameter is directed vertically.
The meatus urinarius is the most contracted part of the urethra ; it is a vertical
slit, about three lines in length, bounded on each side by two small labia. The
inner surface of the lining membrane of the urethra, especially on the floor of the
spongy portion, presents the orifices of numerous mucous glands and follicles,
situated in the submucous tissue, and named the glands of Littre. They vary in
size, and their orifices are directed forwards, so that they may easily intercept the
point of a catheter in its passage along the canal. One of these lacunte, larger
than the rest, is situated on the upper surface of the fossa navicularis, about an
inch and a half from the orifice ; it is called the lacuna magna. Into the bulbous
portion are found opening the ducts of Cowper's glands.
Structure. The urethra is composed of three coats : a mucous, muscular, and
erectile.
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 prolonged into
the ducts of the numerous glands which open into the urethra, viz., Cowper's
glands, and the prostate gland ; and, through the ejaculatory ducts, is continued into
the vasa deferentia and vesiculse seminales. In the spongy and membranous
portions, the mucous membrane is arranged in longitudinal folds when the organ
734 URINARY ORGANS.
is contracted. Small papillae are found upon it, near the orifice ; and its epithe-
lial lining is of the columnar variety, excepting near the meatus, where it is
laminated.
The muscular coat consists of two layers of plain muscular fibres, an external
longitudinal layer, and an internal circular. The muscular tissue is most abundant
in the prostatic portion of the canal.
A thin layer of erectile tissue is continued from the corpus spongiosum round
the membranous and prostatic portions of the urethra to the neck of the bladder.
Male Generative Organs.
Prostate Gland.
The Prostate Gland (rtpoCat^fii, to stand before) is a pale, firm, glandular body,
which surrounds the neck of the bladder and commencement of the urethra. It
is placed in the pelvic cavity, behind and below the symphysis pubis, posterior
to the deep perineal fascia, and upon the rectum, through which it may be distinctly
felt, especially when enlarged. In shape and size it resembles a horse-chestnut.
Its base is directed backwards towards the neck of the bladder.
The apex is directed forwards to the deep perineal fascia, which it touches.
Its under surface is smooth, and rests on the rectum, to which it is connected
by a dense areolar fibrous tissue.
Its upper 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;
and its weight is about six drachms. It is held in its position by the anterior
ligaments of the bladder (pubo-prostatic) ; by the posterior layer of the deep
perineal fascia, which invests the commencement of the membranous portion of
the urethra and prostate gland ; and by the anterior portion of the Levator ani
muscle {levator prostatae), which passes down on each side from the symphysis pubis
and anterior ligament of the bladder to the sides of the prostate.
The prostate consists of three lobes ; two lateral and a middle lobe.
The two lateral lobes are of equal size, separated behind by a deep notch, and
marked by a slight furrow upon their upper and lower surface, which indicates
the bi-lobed condition of the organ in some animals.
The third or middle lobe is a small, transverse band, occasionally a rounded or
triangular prominence, placed between the two lateral lobes at the under and
posterior part of the organ. It lies immediately beneath the neck of the bladder,
behind the commencement of the urethra, and above the ejaculatory ducts. Its
existence is not constant, but it is occasionally found at an early period of life, as
well as in adults, and in old age. In advanced life it often becomes considerably
enlarged, and projects into the bladder, so as to impede the evacuation of the urine.
The prostate gland is perforated by the urethra and common seminal ducts.
The urethra usually lies about one-third nearer its upper than its lower surface ;
occasionally, the prostate surrounds only the lower three-fourths of this tube, and
it more rarely runs through the lower than the upper part of the gland. The
ejaculatory ducts pass forwards obliquely through a conical canal, situated in the
lower part of the prostate, and open into the prostatic portion of the urethra.
Structure. The prostate is inclosed in a thin but firm fibrous capsule, distinct
from that derived from the posterior layer of the deep perineal fascia, and sepa-
rated from it by a plexus of veins. Its substance is of a pale, reddish-gray color,
very friable, but of great density. It consists of glandular substance and muscular
tissue.
The glandular substance is composed of numerous follicular pouches, opening
into elongated canals, which join to form from twelve to twenty small excretory
ducts. The follicles are connected together by areolar tissue, supported by pro-
longations from the fibrous capsule, and inclosed in a delicate capillary plexus.
The epithelium lining the canals is columnar, whilst that in the terminal vesicles
is of the squamous variety.
The muscular tissue of the prostate is arranged in the form of circular bands
735
736 MALE GENERATIVE ORGANS.
round the urethra ; it is continuous behind with the circular fibres of the sphincter
vesicae, and in front with the circular fibres of the urethra. The muscular fibres
are of the involuntary kind. The prostatic ducts open into the floor of the
prostatic portion of the urethra.
Vessels and Nerves. The arteries supplying the prostate are derived from the
internal pudic, vesical, and hemorrhoidal. Its veins form a plexus around the
sides and base of the gland ; they communicate in front with the dorsal vein of
the penis, and terminate in the internal iliac vein. The nerves are derived from
the hypogastric plexus.
The Prostatic Secretion is a milky fluid, having an acid reaction, and presenting,
on microscopic examination, molecular matter, the squamous and columnar forms
of epithelium, and granular nuclei. In old age, this gland is liable to be enlarged,
and its ducts are often filled with innumerable small concretions, of a brownish-red
color, and of the size of a millet-seed, composed of carbonate of lime and animal
matter.
Cowper's Glands.
Cowper's Glands are two small rounded and somewhat lobulated bodies, of a
yellowish color, about the size of peas, placed beneath the fore part of the
membranous portion of the urethra, between the two layers of the deep perineal
fascia. They lie close behind the bulb, and are inclosed by the transverse fibres
of the Compressor urethras muscle. Each gland consists of several lobules, held
together by a fibrous investment. The excretory duct of each gland, nearly an
inch in length, passes obliquely forwards beneath the mucous membrane, and
opens by a minute orifice on the floor of the bulbous portion of the urethra.
Their existence is said to be constant ; they gradually diminish in size as age
advances.
The Penis.
The Penis is the organ of copulation, and contains in its interior the larger
portion of the urethra. It consists of a root, body, and the extremity or glans
penis.
The root is broad and firmly connected to the rami of the pubes by two strong
tapering fibrous processes, the crura, and to the front of the symphysis pubis by
a fibrous membrane, the suspensory ligament.
The extremity or glans penis presents the form of an obtuse cone, flattened from
above downwards. At its summit is a vertical fissure, the orifice of the urethra,
meatus urinarius ; and at the back part of this orifice a fold of mucous membrane
passes backwards to the bottom of a depressed raphe, where it is continuous with
the prepuce ; this fold is termed the froenum preputii. The base of the glans forms
a rounded projecting border, the corona glandis ; and behind the corona is a deep
constriction, the cervix. Upon both of these parts numerous small lenticular
sebaceous glands are found, the glandulse Tysonii sou odoriferve. They secrete a
sebaceous matter of very peculiar odor, which probably contains casein, and
becomes easily decomposed.
The body of the penis is the part between the root and the extremity. In the
flaccid condition of the organ it is cylindrical, but when erect has a triangular
prismatic form with rounded angles, the broadest side being turned upwards, and
called the dorsum. It is covered by integument remarkable for its thinness, its
dark color, its looseness of connection with the deeper parts of the organ, and
from containing no adipose tissue. At the root of the penis the integument is
continuous 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.
The internal layer of the prepuce, which also becomes attached to the cervix,
approaches in character to a mucous membrane ; it is reflected over the glans
penis, and at the meatus urinarius is continuous with the mucous lining of the
urethra.
PE^IS. T37
Tlie mucous membrane covering the glans penis contains no sebaceous glands ;
but projecting from its free surface are a number of small, highly sensitive
papillae. ,
The penis is composed of a mass of erectile tissue, inclosed in three cylindrical
fibrous compartments. Two of these, the corpora cavernosa, are placed side by
side along the upper part of the organ ; the third or corpus spongiosum incloses
the urethra, and is placed below.
The 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 con-
nected along the median line for their anterior three-fourths, their posterior fourth
being separated to form the two crura, by which the penis is connected to the
rami of the pubes. Each crus commences by a thick-pointed process in front of
the tuberosity of the ischium ; and, near its junction with its fellow, 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. A median groove on the upper surface
lodges the dorsal vein of the penis, and the groove on the under surface receives
the corpus spongiosum. The root of the penis is connected to the symphysis
pubis by the suspensory ligament.
Structure. Each corpus cavernosum consists of a strong fibrous envelop,
inclosing a fibrous reticular structure, containing erectile tissue in its meshes. It
is separated from its fellow by an incomplete fibrous septum.
The fibrous investment is extremely dense, of considerable thickness, and highly
elastic ; it not only invests the surface of the organ, but sends off numerous fibrous
bands (trabeculse) from its inner surface, as well as from the surface of the septum,
which cross its interior in all directions, subdividing it into a number of separate
compartments, which present a spongy structure, in which the erectile tissue is
contained.
The trabecular structure fills the interior of the corpora cavernosa. Its com-
ponent fibres are larger and stronger round the circumference than at the centre
of the corpora cavernosa; they are also thicker behind than in front. The inter-
spaces, on the contrary, are larger at the centre than at the circumference, their
long diameter being directed transversely ; and they are largest anteriorly. They
are lined by a layer of squamous epithelium.
The fibrous septum forms an imperfect partition between the two corpora caver-
nosa ; it is thick and complete behind, but in front it is incomplete, and consists of
a number of vertical bands of fibrous tissue, which are arranged like the teeth of
a comb ; hence the name, septum pectiniforme. These bands extend between the
dorsal and urethral surface of the corpora cavernosa.
The fibrous investment and septum consist of longitudinal bands of white fibrous
tissue, with numerous elastic and muscular fibres. The trabecule also consist of
white fibrous tissue, elastic fibres, and plain muscular fibres, and inclose arteries
and nerves.
The Corpus Spongiosum incloses the urethra, and is situated in the groove on
the under surface of the corpora cavernosa. It commences posteriorly in front
of the deep perineal fascia, between the diverging crura of the corpora cavernosa,
where it forms a rounded enlargement, the bulb ; and terminates, anteriorly, in
another expansion, the glans penis, which overlays the anterior rounded extremity
of the corpora cavernosa ; its central portion or body is cylindrical, and tapers
slightly from behind forwards.
The bulb varies in size in different subjects ; it receives a fibrous investment
from the anterior layer of the deep perineal fascia, and is surrounded by the
Accelerator urinse muscle. The urethra enters the bulb nearer its upper than its
lower surface, being surrounded by a layer of erectile tissue, named, by Kobelt,
the colliculi bulbi, a thin prolongation of which is continued backwards round
the membranous and prostatic portions of the canal to the neck of the bladder,
47
738 MALE GENERATIVE ORGANS.
lying immediately beneath the mucous membrane. The portion of the bulb
below the urethra presents a partial division into two lobes, being marked
externally by a linear raphe, whilst internally there projects inwards, for a short
distance, a thin fibrous septum, most distinct in early life.
Structure. The corpus spongiosum consists of a strong fibrous envelop, inclosing
a trabecular structure, which contains in its meshes erectile tissue. The fibrous
envelop is thinner, whiter in color, and more elastic than that of the corpus
cavernosum. The trabeculse are delicate, uniform in size, and the meshes between
them small ; their long diameter, for the most part, corresponding with that of
the penis. A thin layer of muscular fibres, continuous behind with those of the
bladder, forms part of the outer coat of the corpus spongiosum.
Erectile tissue consists essentially of an intricate venous plexus, lodged in the
interspaces between the trabeculse. The veins forming this plexus are so
numerous, and communicate so freely with one another, as to present a cellular
appearance when examined by means of a section; their walls are extremely thin,
and lined by squamous epithelium. The veins are smaller in the glans penis,
corpus spongiosum, and circumference of the corpora cavernosa, than in the central
part of the latter, where they are of large size, and much dilated. They return
the blood by a series of vessels, some of which emerge in considerable numbers
from the base of the glans penis, and converge on the dorsum of the organ to form
the 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 round 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 and pudendal veins.
The arteries of the penis are derived from the internal pudic. Those supplying
the corpora cavernosa are the arteries of the corpora cavernosa, and branches from
the dorsal artery of the penis, which perforate the fibrous capsule near the fore
part of the organ. Those to the corpus spongiosum are the arteries of the bulb.
Additional branches are described, by Kobelt, as arising from the trunk of the
internal pudic ; they enter the bulbous enlargement on the corpora cavernosa and
corpus spongiosum. The arteries, on entering the cavernous structure, divide into
branches, which are supported and inclosed by the trabecular ; according to Muller,
some of these branches terminate in a capillary network, which communicates with
the veins as in other parts; whilst others are more convoluted, and assume a tendril-
like appearance; hence the name, helicine arteries, which is given to these peculiar
vessels. The helicine arteries are most abundant in the back part of the corpora
cavernosa and corpus spongiosum ; they have not been seen in the glans penis.
The existence of these vessels is denied by Valentin, who describes the smallest
branches of the arteries as terminating by wide, funnel-shaped orifices, which open
directly into the venous cavities.
The lymphatics of the penis consist of a superficial and deep set ; the former
terminate in the inguinal glands, the latter emerge from the corpora cavernosa
and corpus spongiosum, and, passing beneath the pubic arch, join the deep lym-
phatics of the pelvis.
The nerves are derived from the internal pudic nerve and the hypogastric plexus.
On the glans and bulb, some filaments of the cutaneous nerves have Pacinian
bodies connected with them.
The Testes.
The Testes are two small glandular organs, which secrete the semen ; they are
situated in the scrotum, being suspended by the spermatic cords. Each is of an
oval form, compressed laterally and behind, and having an oblique position in the
scrotum ; the upper extremity being directed forwards and a little outwards ; the
lower, backwards and a little inwards; the anterior convex border looks forwards
and downwards, the posterior or straight border, to which the cord is attached,
backwards and upwards.
COVERINGS OF THE TESTES. 739
The anterior and lateral surfaces, as well as both extremities of the organ, are
convex, free, smooth, and invested by a serous covering called the tunica vaginalis.
The posterior border, to which the cord is attached, receives only a partial invest-
ment from this membrane. Lying upon the outer edge of this border, is a long,
narrow, flattened body, named, from its relation to the testis, the epididymis (««
AiSi^o;, testis). It consists of a central portion or body, an upper enlarged ex-
tremity, the globus major or head ; and a lower pointed extremity, the tail or
globus minor. The globus major 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
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 connected to the back of the testis by a fold of the serous
membrane. Attached to the upper end of the testis, or to the epididymis, is a
small pedunculated body, the use of which is unknown.
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.
Coverings. At an early period of foetal life, the testes are contained in the abdo-
minal cavity, behind the peritoneum. Before birth, they descend to the inguinal
canal, along which they pass with the spermatic cord, and, emerging at the external
abdominal ring, they descend into the scrotum, becoming invested in their course
by numerous coverings, derived from the serous, muscular, and fibrous layers of
the abdominal parietes, as well as by the scrotum. The coverings of the testis
are the
Skin ) G ,
-p. , \ Scrotum.
Dartos j
Intercolumnar or External spermatic fascia.
Cremaster muscle.
Infundibuliform fascia, Fascia propria or Internal spermatic fascia.
Tunica vaginalis.
The Scrotum is a cutaneous pouch, which contains the testes and part of the
spermatic cords. It is divided into two lateral halves, by a median line or raphe,
which is continued forwards along the under surface of the penis, and backwards
along the middle line of the perineum to the anus. Of these two lateral portions,
the left is longer than the right, and corresponds with the. 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 scrotum consists of two layers, the integument and the darto;-;.
The integument is very thin, of a brownish color, and generally 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 is a thin layer of loose reddish tissue, endowed with contractility ;
it forms the proper tunic of the scrotum, is continuous, around the base of the
scrotum, with the superficial fascia of the groin, perineum, and inner side of the
thighs, and sends inwards a distinct septum, septum scroti, which divides it into
two cavities for the two testes, the septum extending between the raphe and under
surface of the penis, as far as its root.
The dartos is closely united to the skin externally, but connected with the
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. Its contractility is slow, and excited by cold
and mechanical stimuli, but not by electricity.
?40
MALE GENERATIVE ORGANS.
Fig. 371.— The Testis in Situ : the Tunica
Vaginalis having been laid open.
Artery
of Cord
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, being prolonged downwards around the surface of the cord and testis. It
is separated from the dartos by loose areolar tissue, which allows of considerable
movement of the latter upon it, but is intimately connected with the succeeding
layer.
The cremasteric fascia consists of scattered bundles of muscular fibres ( Cremaster
muscle), derived from the lower border of the Internal oblique muscle, during the
descent of the testis.
The fascia propria is a thin membranous layer, which loosely invests the
surface of the cord. It is a continuation downwards of the infundibuliform pro-
cess of the fascia transversalis, and is also derived during the descent of the testis
in the foetus.
The tunica vaginalis is described more appropriately, as one of the proper
coverings of the testis. A more detailed account of the coverings just described
may be found in the description of the surgical anatomy of inguinal hernia.
Proper coverings or investments of the Testis. The testis is invested by three
tunics, the tunica vaginalis, tunica albu-
ginea, and tunica vasculosa.
The Tunica Vaginalis is the serous
covering of the testis. It is a pouch of
serous membrane, derived from the peri-
toneum during the descent of the testis,
in the foetus, from the abdomen into the
scrotum. After its descent, that portion
of the pouch which extends from the
internal ring to near the upper part of
the gland becomes obliterated, the lower
portion remaining as a shut sac, which
invests the outer surface of the testis, and
is reflected on the internal surface of the
scrotum ; hence it may be described as
consisting of a visceral and parietal por-
tion.
The visceral portion {tunica vaginalis
propria) covers the outer surface of the
testis, as well as the epididymis, con-
necting 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 scrotum.
The parietal portion of the serous membrane (tunica vaginalis reflexa) is far
more extensive than the visceral portion, extending upwards 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 squamous
epithelium. The interval between the visceral and parietal layers of this mem-
brane constitutes the cavity of the tunica vaginalis.
The Tunica ATbuginea 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 direction. Its outer surface is covered by the tunica
vaginalis, except along its posterior border, and at the points of attachment of
the epididymis ; hence the tunica albuginea is usually considered as a fibro-serous
membrane, like the dura mater and pericardium. This membrane surrounds the
glandular structure of the testicle, and, at its posterior and upper border, is
reflected into the interior of the gland, forming an incomplete vertical septum,
called the mediastinum testis {corpus Highmorianum).
The mediastinum testis extends from the upper, nearly to the lower, border of
<Jie gland, and is wider above than below. From the front and sides of this
Tun/ra Vaginalis ^
parietal layer
SPERMATIC CORD — TESTIS.
741
Fig. 372.— Vertical Section of the Tes-
ticle, to show the arrangement of the
Ducts.
septum, numerous slender fibrous cords (trabecule) are given off, which pass to be
attached to the inner surface of the tunica albuginea ; they serve to maintain the
form of the testis, and join, with similar cords given off from the inner surface of
the tunica albuginea, to form spaces which inclose the separate lobules of the organ.
The mediastinum supports the vessels and ducts of the testis in their passage to
and from the substance of the gland.
The Tunica Vasculosa (pia mater testis) is the vascular layer of the testis,
consisting of a plexus of bloodvessels, held together by a delicate areolar tissue.
It covers the inner surface of the tunica albuginea, sending off numerous processes
between the lobules, which are supported by the fibrous prolongations from the
mediastinum testis.
Structure of the Testis. The glandular structure of the testis consists of nume-
rous 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. Each lobule is conical
in shape, the base being directed towards the circumference of the organ, the apex
towards 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, the tubuli seminiferi. The tubes may be separately
unravelled, by careful dissection under water, and may be seen to commence
either by free cgecal ends, or by anasto-
motic loops. The total number of tubes
is considered by Monro 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. Their diameter varies
from 3£&th to T50th of an inch. The
tubuli are pale in color in early life, but,
in old age, they acquire a deep yellow
tinge, from containing much fatty matter.
They consist of a basement membrane,
lined by epithelium, consisting of nucle-
ated granular corpuscles, and are inclosed
in a delicate plexus of capillary vessels.
In the apices of the lobules, the tubuli
become less convoluted, assume a nearly
straight course, and unite together to form
from twenty to thirty larger ducts, of
about 5'0th of an inch in diameter, and
these, from their straight course, are called
vasa recta.
The vasa recta enter the fibrous tissue
of the mediastinum, and pass upwards and
backwards, forming, in their ascent, a
close network of anastomosing tubes, with
exceedingly thin parietes ; this constitutes the rete testis. At the upper end of the
mediastinum, the vessels of the rete testis terminate in from twelve to fifteen or
twenty ducts, the vasa efferentia: they perforate the tunica albuginea, and carry
the seminal fluid from the testis to the epididymis. Their course is at first
straight ; they then become enlarged, and exceedingly convoluted, and form a
series of conical masses, the cord vasculosi, which, together, constitute the globus
major of the epididymis. Each cone consists of a single convoluted duct, from
six to eight inches in length, the diameter of which gradually decreases from the
testis to the epididymis. Opposite the bases of the cones, the efferent vessels
open at narrow intervals into a single duct, which constitutes, by its complex
742 MALE GENERATIVE ORGANS.
convolutions, the body and globus minor of the epididymis. "When the convolu-
tions of this tube are unravelled, it measures upwards of twenty feet in length,
and increases in breadth and thickness as it approaches the vas deferens. The
convolutions are held together by fine areolar tissue, and by bands of fibrous
tissue. A long narrow tube, the vasculum aberrans of Haller, is occasionally found
connected with the lower part of the canal of the epididymis, or with the com-
mencement of the vas deferens, and extending up into the cord for about two or
three inches, where it terminates by a blind extremity, which is occasionally
bifurcated. Its length varies from an inch and a half to fourteen inches, and
sometimes it becomes dilated towards its extremity ; more commonly, it retains
the same diameter throughout. Its structure is similar to that of the vas deferens.
Occasionally, it is found unconnected with the epididymis.
Vas Deferens. The 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 and inner side of the testis and epididymis,
and along the back part of the spermatic cord, through the spermatic canal, to the
internal abdominal ring. From the ring it descends into the pelvis, crossing the
external iliac vessels, and curves round the outer side of the epigastric artery ; at
the side of the bladder, it arches backwards and downwards to its base, crossing
outside the obliterated hypogastric artery, and to the inner side of the ureter. At
the base of the bladder, it lies between it and the rectum, running along the inner
border of the vesicula seminalis. In this situation, it becomes enlarged and sac-
culated ; and, becoming narrowed, at the base of the prostate, unites with the duct
of the vesicula seminalis to form the ejaculatory duct. The vas deferens presents
a hard and cordy sensation to the fingers, is about two feet in length, of cylin-
drical form, and about a line and a quarter in diameter. Its Avails are of extreme
density and thickness, measuring one-third of a line ; and its canal is extremely
small, measuring about half a line.
In structure, the vas deferens consists of three coats ; an external or cellular
coat ; a muscular coat, which is thick, dense, elastic, and consists of two longitu-
dinal layers, and an intermediate circular layer of muscular fibres, and an internal
or mucous coat, which is pale, and arranged in longitudinal plicae : its epithelial
covering is of the columnar variety.
Vessels and Nerves of the Testes. The arteries supplying the coverings of the
testes are the superficial and deep external pudic from the femoral ; the superficial
perineal branch of the internal pudic, and the cremasteric branch from the epi-
gastric. The veins follow the course of the corresponding arteries. The lymphatics
terminate in the inguinal glands. The nerves are the ilio-inguinal and ilio-
hypogastric branches of the lumbar plexus, the two superficial perineal branches
of the internal pudic nerve, the inferior pudenal branch of the small sciatic nerve,
and the genital branch of the genito-crural nerve.
Spermatic Cord. 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. It is composed of arteries, veins, lymphatics, nerves, and the excre-
tory duct of the testicle, connected together by areolar tissue, and invested by its
proper coverings. In the abdominal wall, it passes obliquely along the inguinal
canal, lying at first beneath the Internal oblique, 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 rather longer than the right, consequently the left testis hangs some-
what lower than its fellow.
The arteries of the cord are the spermatic, from the aorta ; the artery of the
vas deferens, from the superior vesical ; and the cremasteric, from the epigastric
artery.
The spermatic artery supplies the testicle. On approaching this gland, some
branches supply the epididymis, others perforate the tunica albuginea behind, and
YAS DEFERENS— YESICTTL^E SEMINALES.
743
spread out on its inner surface, or pass through the fibrous septum in its interior,
to be distributed on the membranous septa, between the separate lobes.
The artery of the vas deferens is a long slender vessel, which accompanies the
vas deferens, ramifying upon the coats of this duct, and anastomosing with the
spermatic artery near the testis.
The cremasteric branch from the epigastric supplies the Cremaster muscle, and
other coverings of the cord.
The spermatic veins leave the back part of the testis, and, receiving branches
from the epididymis, unite to form a plexus {pampiniform plexus), which forms
the chief mass of the cord. They pass up in front of the vas deferens, and unite
to form a single trunk, which terminates, on the right side in the inferior vena
cava, on the left side in the left renal vein.
The lymphatics are of large size, accompany the bloodvessels, and terminate
in the lumbar glands.
The nerves are the spermatic plexus from the sympathetic. This plexus is
derived from the renal and aortic plexuses, joined by filaments from the hypogastric
plexus, which accompany the artery of the vas deferens.
Yesicul^: Seminales.
The Seminal Yesicles are two lobulated membranous pouches, placed between
the base of the bladder and the rectum, serving as reservoirs for the semen, and
Fig. 373. — Base of the Bladder, with the Vasa Deferentia
and Vesicular Seuiiuales.
Bight Ej'aruUtory
secreting some fluid to be added to that of the testicles. Each sac is somewhat
pyramidal in form, the broad end being directed backwards, and the narrow end
forwards towards the prostate. They measure about two and a half inches in
length, about five lines in breadth, and from two to three lines in thickness.
They vary, however, in size, not only in different individuals, but also in the same
individual on the two sides. Their 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. Their under surface rests upon the rectum, from which they are
separated by the recto-vesical fascia. Their posterior extremities diverge back-
144 MALE GENERATIVE ORGANS:
wards and outwards from each other. The anterior extremities are pointed, and
converge towards the base of the prostate gland, where each joins witli the
corresponding vas deferens to form the ejaculatory duct. Along the inner margin
of each vesicula runs the enlarged and convoluted vas deferens. The inner border
of the vesicula, and the corresponding vas deferens, form the lateral boundary 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, and corresponds with
the trigonum vesicae in its interior.
Structure. Each vesicula consists of a single tube, coiled upon itself, and giving
off several irregular cascal diverticula ; 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
posteriorly in a cul-de-sac, but its anterior extremity becomes constricted into a
narrow straight duct, which joins on its inner side with the corresponding vas
deferens, and forms the ejaculatory duct.
The ejaculatory ducts, two in number, one on each side, are formed by the
junction of the duct of the vesicula seminalis with the vas deferens. Each duct
is about three quarters of an inch in length ; it commences at the base of the
prostate, and runs forwards and upwards in a canal in its substance, and along
the side of the utriculus, to terminate by a separate slit-like orifice upon or within
the margins of the sinus pocularis. The ducts diminish in size, and converge
towards their termination.
Structure. The vesiculaa seminales are composed of three coats : — external or
fibro-cellular, derived from the recto-vesical fascia ; middle or fibrous coat, which
is firm, dense, fibrous in structure, somewhat elastic, and contains, according to
E. H. Weber, muscular fibres ; and an internal or mucous coat, which is pale, of a
whitish-brown color, and presents a delicate reticular structure, like that seen in
the gall-bladder, but the meshes are finer. It is lined by squamous epithelium.
The coats of the ejaculatory ducts are extremely thin, the outer fibrous layer being
almost entirely lost after their entrance into the prostate, a thin layer of muscular
fibres and the mucous membrane forming the only constituent parts of these
tubes.
Vessels and Nerves. The arteries supplying the vesiculas seminales are derived
from the inferior vesical and middle hemorrhoidal. The veins and lymphatics
accompany the arteries. The nerves are derived from the Irypogastric plexus.
The Semen is a thick whitish fluid, having a peculiar odor. It consists of a
fluid called the liquor seminis, and solid particles, viz : — the seminal granules and
spermatozoa.
The liquor seminis is transparent, colorless, and of an albuminous compo-
sition, containing particles of squamous and columnar epithelium, with oil globules
and granular matter floating in it, besides the above-mentioned solid elements.
The seminal granules are round finely-granular corpuscles, measuring 1TJVtfth
of an inch in diameter.
The spermatozoa or spermatic filaments are the essential agents in producing
fecundation. They are minute elongated particles, consisting of a small flattened
oval extremity or body, and a long slender caudal filament. A small circular
spot is observed in the centre of the body, and at its point of connection with
the tail there is frequently seen a projecting rim or collar. The movements of
these bodies are remarkable, and consist of a lashing or undulatory motion of the
tail.
Descent of the Testes.
The Testes, at an early period of foetal life, are placed at the back part of the
abdominal cavity, behind the peritoneum, in front of, and a little below, the kidneys.
The anterior surface and sides are invested by peritoneum; the bloodvessels and
efferent ducts are connected with their posterior surface ; and attached to the
DESCENT OP THE TESTES. 745
lower end is a peculiar structure, the gubernaculum testis, which is said to assist
in their descent.
The Gubernaculum Testis attains its full development between the fifth and
sixth months ; it is a conical-shaped cord, attached above to the lower end of the
epididymis, and below to the bottom of the scrotum. It is placed behind the
peritoneum, lying upon the front of the Psoas muscle, and completely filling the
inguinal canal. It consists of a soft transparent areolar tissue within, which often
appears partially hollow, surrounded by a layer of striped muscular fibres, the
Cremaster, which ascends upon this body to be attached to the testis. According
to Mr. Curling, the gubernaculum, as well as these muscular fibres, divides below
into three processes ; the external and broadest process is connected with Poupart's
ligament in the inguinal canal ; the middle process descends along the inguinal canal
to the bottom of the scrotum, where it joins the dartos ; the internal one is firmly
attached to the os pubis and sheath of the Pectus muscle; some fibres, moreover,
are reflected from the Internal oblique on to the front of the gubernaculum. Up
to the fifth month, the testis is situated in the lumbar region, covered in front and
at the sides by peritoneum, and supported in its position by a fold of this mem-
brane, the mesorchium ; between the fifth and sixth months the testis descends to
the iliac fossa, the gubernaculum at the same time becoming shortened ; during
the seventh month, it enters the internal abdominal ring, a small pouch of perito-
neum (processus vaginalis) preceding the testis in its course through the canal.
By the end of the eighth month, the testis has descended into the scrotum, carry-
ing down with it a lengthened pouch of peritoneum, which communicates by its
upper extremity with the peritoneal cavity. Just before birth, the upper part of
this pouch becomes closed, and this obliteration extends gradually downwards to
within a short distance 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.
Mr. Curling considers that the descent of the testis is effected by means of the
muscular fibres of the gubernaculum ; those fibres which proceed from Poupart's
ligament and the Obliquus internus are said to guide the organ into the inguinal
canal ; those attached to the pubis draw it below the external abdominal ring ; and
those attached to the bottom of the scrotum complete its descent. During the
descent of the organ these muscular fibres become gradually everted, forming a
muscular layer, which becomes placed external to the process of peritoneum,
surrounding the gland and spermatic cord, and constitutes the Cremaster. 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 Nuch.
Female Organs of Generation.
The External Organs of Generation in the female are the mons Veneris, the
labia majora and minora, the clitoris, the meatus urinarius, and the orifice of the
vagina. The term " vulva" or " pudendum," as generally applied, includes all
these parts.
The mons veneris is the rounded eminence in front of the pubes, formed by a
collection of fatty tissue beneath the integument. It surmounts the vulva, and is
covered with hair at the time of puberty.
Fig. 374.— The Vulva. External Female Organs of Generation.
The labia majora are two prominent longitudinal cutaneous folds, extending
downwards from the mons Veneris to the anterior boundary of the perineum, and
inclosing an elliptical fissure, the common urino-sexual opening. Each labium is
formed externally of integument, covered with hair ; internally, of mucous mem-
brane, which is continuous with the genito-urinary mucous tract ; and between
the two, of a considerable quantity of areolar tissue, fat, and a tissue resembling
746
VULYA. ui
the dartos of the scrotum, besides vessels, nerves, and glands. _ The labia are
thicker in front than behind, and joined together at each extremity, forming the
anterior and posterior commissures. The interval left between the posterior com-
missure and the margin of the anus is about an inch in length, and constitutes the
perineum. Just within the posterior commissure is a small, transverse fold, the
frsenulum pudencU or fourchette, which is commonly ruptured in the first partu-
rition, and the space between it and the commissure is called the fossa navicularis.
The labia are analogous to the scrotum in the male.
The labia minora or nymphse are two small folds of mucous membrane, situated
within the labia majora, and extending from the clitoris obliquely downwards
and outwards for about an inch and a half on each side of the orifice of the
vagina, on the sides of which they are lost. They are continuous externally with
the labia majora, internally with the inner surface of the vagina. As they con-
verge towards the clitoris in front, each labium divides into two folds, which sur-
round the glans clitoridis, the superior folds uniting to form the praeputium clito-
ridis, the inferior folds being attached to the glans, and forming the frasnum. The
nymphae are composed of mucous membrane, covered by a thin epithelial layer.
They contain a plexus of vessels in their interior, and are provided with numer-
ous large mucous crypts which secrete abundance of sebaceous matter.
The clitoris is an erectile structure, analogous to the corpora cavernosa of the
penis. It is situated beneath the anterior commissure, partially hidden between
the anterior extremities of the labia minora. It is an elongated organ, connected
to the rami of the pubes and ischia on each side by two crura ; the body is short,
and concealed beneath the labia ; its free extremity, the glans clitoridis, is a small
rounded tubercle, consisting of spongy erectile tissue, and highly sensitive. The
clitoris consists of two corpora cavernosa, composed of erectile tissue inclosed in
a dense layer of fibrous membrane, united together along their inner surfaces by
an incomplete fibrous pectiniform septum. It is provided, like the penis, with
a suspensory ligament, and with two small muscles, the Erectores clitoridis, which
are inserted into the crura of the corpora cavernosa.
Between the clitoris and the entrance of the vagina is a triangular smooth
surface, bounded on each side by the nymphas ; this is the vestibule.
The orifice of the urethra {meatus urinarius) is situated at the back part of the
vestibule, about an inch below the clitoris, and near the margin of the vagina,
surrounded by a prominent elevation of the mucous membrane. Below the
meatus urinarius is the orifice of the vagina, an elliptical aperture, more or less
closed in the virgin by a membranous fold, the hymen.
The hymen is a thin semilunar fold of mucous membrane, stretched across the
lower part of the orifice of the vagina ; its concave margin being turned upwards
towards the pubes. Sometimes this membrane forms a complete septum across
the orifice of the vagina, which constitutes an imperforate hymen. Occa-
sionally, it forms a circular septum, perforated in the centre by a round open
ing; sometimes it is cribriform, or its free margin forms a membranous fringe,
or it may be entirely absent. The hymen cannot, consequently, be considered as
a proof of virginity. Its rupture, or the rudimentary condition of the membrane
above referred to, gives rise to those small rounded elevations which surround
the opening of the vagina, the carunculse myrtiformes.
Glands of Bartholine. On each side 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 Bartholine.
Each gland opens by means of a long single duct, upon the inner side of the
nymphaa, external to the hymen. Extending from the clitoris, along either side of
the vestibule, and lying a little behind the nymphee, are two large oblong masses,
about an inch in length, consisting of a plexus of veins, inclosed in a thin layer
of fibrous membrane. These bodies are narrow in front, rounded below, and are
connected with the crura of the clitoris and rami of the pubes ; they are termed
by Kobelt, the bulbi vestibuli, and he considers them analogous to the bulb of
748
FEMALE ORGANS OP GENERATION.
the corpus spongiosum in the male. Immediately in front of these bodies is a
smaller venous plexus, continuous with the bulbi vestibuli behind, and the glans
clitoridis in front ; it is called by Kobelt, the pars intermedia, and is considered
by him as analogous to that part of the body of the corpus spongiosum which
immediately succeeds the bulb.
Fig. 375. — Section of Female Pelvis, showing position of Viscera.
Bladder.
The Bladder is situated at the anterior part of the pelvis. It is in relation,
in front, with the os pubis ; behind, with the uterus, some convolutions of the
small intestine being interposed ; its base lies in contact with the neck of the
uterus, and with the anterior wall of the vagina. The bladder is larger in the
female than in the male, and very broad in its transverse diameter.
Urethra.
The Urethra is a narrow membranous canal, about an inch and a half in length,
extending from the neck of the bladder to the meatus urinarius. It is placed
beneath the symphysis pubis, imbedded in the anterior wall of the vagina ; and
its direction is obliquely downwards and forwards, its course being slightly
curved, the concavity directed upwards. Its diameter, when undilated, is about
a quarter of an inch. The urethra perforates the triangular ligament, precisely
as in the male, and is surrounded by the muscular fibres of the Compressor
urethrse.
Structure. The urethra consists of three coats ; muscular erectile, and mucous.
The muscular coat is continuous with that of the bladder : it extends the whole
length of the tube, and consists of a thick stratum of circular fibres.
VAGINA. U9
A thin layer of spongy, erectile tissue, intermixed with much elastic tissue,
lies immediately beneath the mucous coat.
The mucous coat is pale, continuous, externally, with 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, resembles the veru montanum in the male
urethra. It is lined by laminated epithelium, which becomes spheroidal at the
bladder. Its external orifice is surrounded by a few mucous follicles.
The urethra, from not being surrounded by dense resisting structures, as in the
male, admits of considerable dilatation, which enables the surgeon to remove with
considerable facility, calculi, or other foreign bodies, from the cavity of the
bladder.
Kectum.
The Kectum is more capacious, and less curved in the female, than in the male.
The first portion extends from the left sacro-iliac symphysis to the middle of
the sacrum. Its connections are similar to those in the male.
The second portion extends to the tip of the coccyx. It is covered in front by
the peritoneum, but only for a short distance, at its upper part, and is in relation
with the posterior wall of the vagina.
The third portion curves backwards, from the vagina to the anus, leaving a
space which corresponds on the surface of the body to the perineum. Its ex-
tremity is surrounded by the Sphincter muscles, and its sides are supported by
the Levatores ani.
The Vagina.
The Vagina is a membranous canal, extending 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 forwards and downwards, following at first
the line of the axis of the cavity of the pelvis, and afterwards that of the outlet.
It is cylindrical in shape, flattened from before backwards, and its walls are
ordinarily in contact with each other. Its length is about four inches along its
anterior wall, and between five or six along its posterior wall. It is constricted
at its commencement, and becomes dilated near the uterine extremity ; it surrounds
the vaginal portion of the cervix uteri, a short distance from the os, and its at-
tachment extends higher up on the posterior than on the anterior wall.
Relations. Its anterior surface is concave, and in relation with the base of the
bladder, and with the urethra. Its posterior surface is convex, and connected to
the anterior wall of the rectum, for the lower three-fourths of its extent, the
upper fourth being separated from that tube by the recto-uterine fold of peri-
toneum, which forms a cul-de-sac between the vagina and rectum. Its sides give
attachment superiorly to the broad ligaments, and inferiorly to the Levatores ani
muscles and recto-vesical fascia.
Structure. The vagina consists of an external or muscular coat, a layer of
erectile tissue, and an internal mucous lining.
The muscular coat consists of longitudinal fibres, which surround the vagina,
and 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 erectile tissue is inclosed between two layers of fibrous membrane : it is
more abundant at the lower than at the upper part of the vagina.
The mueom membrane is continuous, above, with that lining the uterus, and
below, with the integument covering the labia majora. Its inner surface presents,
along the anterior and posterior walls, a longitudinal ridge or raphe, called the
column of the vagina, and numerous transverse ridges or rugae extend outwards
from the raphe on each side. These rugae are most distinct near the orifice of
the vagina, especially in females before parturition. They indicate its adaptation
for dilatation, and are calculated to facilitate its enlargement during parturition.
The mucous membrane is covered with conical and filiform papillae, and provided
750 FEMALE ORGANS OF GENERATION.
with mucous glands and follicles, which are especially numerous in its upper part,
and around the cervix uteri.
The Uterus.
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 the
principal agent in its expulsion at the time of parturition.
In the virgin state it is pear-shaped, flattened from before backwards, and
situated in the cavity of the pelvis, between the bladder and rectum ; it is re-
tained in its position by the round and broad ligaments on each side, and projects
into the upper end of the vagina below. Its upper end or base is directed
upwards and forwards ; its lower end or apex downwards and backwards, in the
line of the axis of the inlet of the pelvis, forming an angle with the vagina, the
direction of which corresponds to the cavity and outlet of the pelvis. The uterus
measures about three inches in length, two in breadth, at its upper part, and an
inch in thickness, and it weighs from an ounce to an ounce and a half.
The fundus is the upper broad extremity of the organ ; it is convex, covered
by peritoneum, and placed on a line below the level of the brim of the pelvis.
The body gradually narrows from the fundus to the neck. Its anterior surface
is flattened, covered by peritoneum in the upper three-fourths of its extent, and
separated from the bladder by some convolutions of the small intestine : the lower
fourth is connected with the bladder. Its posterior surface is convex, covered
by peritoneum throughout, and separated from the rectum by some convolutions
of the intestine. Its lateral margins are concave, and give attachment to the
Fallopian tube above, the round ligament below and in front of this, and the
ligament of the ovary behind and below these.
The cervix is the lower rounded and constricted portion of the uterus : around
its circumference is attached the upper end of the vagina, which extends upwards
a greater distance behind than in front.
At the vaginal extremity of the uterus is a transverse aperture, the os uteri,
bounded by two lips, an anterior one, which is thick, and a posterior, narrow and
Ligaments. The ligaments of the uterus are six in number : two anterior, two
posterior, and two lateral. They are formed of peritoneum.
The two anterior ligaments (vesico-uterine) are two semilunar folds, which
pass between the neck of the uterus and the posterior surface of the bladder.
The two posterior ligaments (recto-uterine) pass between the sides of the uterus
and rectum.
The two lateral or broad ligaments pass from the sides of the uterus to the
lateral walls of the pelvis, forming a septum across the pelvis, which divides this
cavity into two portions. In the anterior part are contained the bladder, urethra,
and vagina ; in the posterior part, the rectum.
The cavity of the uterus is small in comparison with the size of the organ :
that portion corresponding to the body is triangular, flattened from before back-
wards, so that its walls are closely approximated, and having its base directed
upwards towards the fundus. At each superior angle is a funnel-shaped cavity,
which constitutes the remains of the 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,
the internal orifice (ostium internum), which leads into the cavity of the cervix.
The cavity of the cervix is somewhat cylindrical, flattened from before backwards,
broader at the centre than at either extremity, and communicates, below, with the
vagina. Each wall of the canal* presents a longitudinal column, from which
proceed a number of small oblique columns, giving the appearance of branches
from the stem of a tree, and hence the name arbor vitve xderinus, applied to it.
These folds usually become very indistinct after the first labor.
UTERUS. 151
Structure. The uterus is composed of three coats : an external serous coat, a
middle or muscular layer, and an internal mucous coat.
The serous coat is derived from the peritoneum ; it invests the fundus and the
whole of the posterior surface of the body of the uterus ; but only the upper
three-fourths of its anterior surface.
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 cuts almost 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, and lymphatic
vessels and nerves. In the impregnated state, the muscular tissue becomes more
prominently developed, and is disposed 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 transversely
across the fundus, and, converging at each superior angle of the uterus, are con-
tinued on the Fallopian tubes, the round ligament, and ligament of the ovary ;
some passing at each side into the broad ligament, and others running backwards
from the cervix into the recto-uterine ligaments.
The middle layer of fibres presents no regularity in its arrangement, being
disposed longitudinally, obliquely, and transversely.
The internal or deep layer consists of circular fibres 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.
At the cervix, these fibres are disposed transversely.
The mucous membrane is thin, smooth, and closely adherent to the subjacent
tissue. It is continuous, through the fimbriated extremity of the Fallopian tubes,
with the peritoneum ; and, through the os uteri, with the mucous lining of the
vagina.
In the body of the uterus, it is smooth, soft, of a reddish color, lined by
columnar-ciliated epithelium, and presents, when viewed with a lens, the orifices
of numerous tubular follicles arranged perpendicularly to the surface. They are
of small size in the unimpregnated uterus, but shortly after impregnation they are
enlarged, elongated, presenting a contorted or waved appearance towards their
closed extremities which occasionally dilate into two or three sacculated extremities.
The circular orifices of these glands may be seen on the inner surface of the
mucous membrane, many of which during the early period of pregnancy are
surrounded by a whitish ring formed of epithelium which lines the follicles.
In the cervix, the mucous membrane between the ruga3 and around the os uteri
is provided with numerous mucous follicles and glands. The small, transparent,
vesicular elevations, so often found within the os and cervix uteri, are due to
closure of the mouths of these follicles, and their distension with their proper
secretion. They were called the ovula of Naboth. The mucous membrane
covering the lower half of the cervix presents numerous papillae.
Vessels and Nerves. 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 veins are of large size, and correspond with the arteries. In the impregnated
uterus, these vessels are termed the uterine sinuses, consisting of the lining mem-
brane of the veins adhering to the walls of canals channelled through the substance
of the uterus. They terminate in the uterine plexuses. The lymphatics are of
large size in the impregnated uterus, and terminate in the pelvic and lumbar
glands. The nerves are derived from the inferior hypogastric and spermatic
plexuses, and from the third and fourth sacral nerves.
The form, size, and situation of the uterus, vary at different periods of life, and under different
circumstances.
Y52 FEMALE ORGANS OF GENERATION.
In tliefcetus, the uterus is contained in the abdominal cavity, projecting beyond the brim of the
pelvis. The cervix is considerably larger than the body.
At puberty, the uterus is pyriform in shape, and weighs from eight to ten drachms. It has
descended into the pelvis, the fundus being just below the level of the brim of this cavity. The
arbor vita? is distinct, and extends to the upper part of the cavity of the organ.
During and after menstruation, the organ is enlarged, and more vascular, its surfaces rounder;
the os externum is rounded, its labia swollen, and the lining membrane of the body thickened,
softer, and of a darker color.
During pregnancy, the uterus increases in weight from one pound and a half to three pounds.
It becomes enormously enlarged, and projects into the hypogastric and lower part of the umbili-
cal regions. This enlargement, which continues up to the sixth month of gestation, is partially
clue to increased development of pre-existing and new-formed muscular tissue. The round liga-
ments are enlarged, and the broad ligaments become encroached upon by the uterus making its
way between their laminae. The mucous membrane becomes more vascular, its mucous follicles
and glands enlarged ; the rugae and folds in the canal of the cervix become obliterated ; the
bloodvessels and lymphatics as well as the nerves, according to the researches of Dr. Lee,
become greatly enlarged.
After parturition, the uterus nearly regains its usual size, weighing from two to three ounces,
but its cavity is larger than in the virgin state ; the external orifice is more marked, and assumes
a transverse direction ; its edges present a fissured surface ; its vessels are tortuous ; and its
muscular layers are more defined.
In old age, the uterus becomes atrophied, and paler and denser in texture ; a more distinct
constriction separates the body and cervix. The ostium internum, and, occasionally, the vaginal
orifice, often become obliterated, and its labia almost entirely disappear.
Appendages of the Uterus.
The appendages of the uterus are the Fallopian tubes, the ovaries and their
ligaments, and the round ligaments. These structures, together with their nutrient
vessels and nerves, and some scattered muscular fibres, are inclosed between the
two folds of peritoneum, which constitute the broad ligaments ; they are placed in
the following order : in front is the round ligament ; the Fallopian tube occupies
the free margin of the broad ligament ; the ovary and its ligament are behind
and below the latter.
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
free 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 in length ; its
canal is exceedingly minute, and commences at the superior angle of the uterus
by a minute orifice, the ostium internum, which will hardly admit a fine bristle ;
it continues narrow along the inner half of the tube ; it then gradually widens
into a trumpet-shaped extremity, which becomes contracted at its termination.
This orifice is called the ostium ahdominale, and communicates with the peritoneal
cavity. Its margins are surrounded by a series of fringe-like processes, termed
fimbriae, and one of these processes is connected with the outer end of the ovary.
To this part of the tube the name fimbriated extremity is applied ; it is also called
morsus diaboli, from the peculiar manner in which it embraces the surface of the
ovary during sexual excitement.
Structure. The Fallopian tube consists of three coats, serous, muscular, and
mucous.
The external or serous coat is derived from the peritoneum.
The middle or muscular coat consists of an external longitudinal and an internal
or circular layer of muscular fibres continuous with those of the uterus.
The internal or mucous coat 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 in the outer part of the tube, which indicate its adaptation for
dilatation, and is covered by columnar-ciliated epithelium. This form of epithe-
lium is also found on the inner and outer surfaces of the fimbriae.
The Ovaries (testes muliebres, Galen) are analogous to the testes in the male.
Thev are oval-shaped bodies, of an elongated form, flattened from above downwards,
situated one on each side of the uterus in the posterior part of the broad ligament,
FALLOPIAN TUBE — OVARY.
753
behind and below the Fallopian tubes. Each ovary is connected, by its anterior
margin, with the broad ligament ; by its inner extremity to the uterus by a proper
ligament, the ligament of the ovary ; and by its outer end to the fimbriated
Fig. 376. — The Uterus and its Appendages. Anterior View.
-**£
EriVc passed throvO^
k'.UUM it I'll
Fig. 377. — Section of the Ovary of a Virgin,
showing the Stroma and Graafian
Vesicles.
extremity of the Fallopian tube by a short ligamentous cord. The ovaries are of
a whitish color, and present either a smooth or 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
surfaces and posterior convex border are free, the anterior straight border being
attached to the broad ligament.
Structure. The ovary is invested by peritoneum, excepting along its anterior
attached margin ; beneath this, is the proper fibrous covering of the organ, the
tunica albuginea, which is extremely
dense and firm in structure, and incloses
a peculiar soft fibrous tissue or stroma,
abundantly supplied with bloodvessels
(fig. 377). Imbedded in the meshes of
this tissue are numerous small, round,
transparent vesicles in various stages of
development ; they are the Graafian vesi-
cles, the ovisacs containing the ova. In
women who have not borne children,
they vary, in number, from ten to fifteen
or twenty, and, in size, from a pin's head to a pea ; but Dr. Martin Barry has
shown, that a large number of microscopic ovisacs exist in the parenchyma of the
organ, few of which produce ova. These vesicles have thin, transparent walls,
and are filled with a clear, colorless, albu-
minous fluid.
The Graafian vesicles are, during their
early development, small, and deeply seat-
ed in the substance of the ovary ; as they
enlarge, they approach the surface ; and,
when mature, form small projections on
the exterior of the ovary beneath the
peritoneum. Each vesicle consists of an
external fibro- vascular coat, connected with
the surrounding stroma of the ovary by
Fig. 378. — Section of the Graafian Vesicle.
(After Von Baer.)
1ni: tLicd- vtitel* v 1
mtmeranA
ttlM—'fH
154 FEMALE ORGANS OF GENERATION.
a network of bloodvessels ; and an internal coat, named the ovi-capsule, which ig
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.
The Ovum is a small spherical body, situated, in immature vesicles, near their
centre ; but, in the mature ones, in contact with the membrana granulosa, at that
part of the vesicle which projects just beneath the surface of the ovary. Accu-
mulated round the ovum, in greater number than at any other point, are the cells
of the membrana granulosa, forming a kind of granular zone, the discus proli-
gerus.
The human ovum is extremely minute, measuring from u\-$ to T2Tr of an inch
in diameter. It consists, externally, of a transparent envelop, the zona pellucida
or vitelline membrane ; within this, and in close contact with it, is the yelk or
vitellus ; imbedded in the substance of the yelk, is a small vesicular body, the
germinal vesicle, which contains the germinal spot.
The zona pellucida or vitelline membrane is a thick, colorless, transparent
membrane, which appears under the mi-
Fig. 379.— Ovum of the Sow. croscope as a bright ring, bounded ex-
( ter any.) ternally and internally by a dark outline.
7^ZMTSk' It corresponds to the chorion of the im-
"^u»sf^' pregnated ovurn.
The yelk consists of granules and glo-
bules of various sizes, imbedded in a more
or less viscid fluid. The smaller gra-
nules resemble pigment ; the larger gra-
nules, which are in greatest number at
the periphery of the yelk, resemble fat-
globules. In the human ovum, the number of granules is comparatively small.
The germinal vesicle consists of a fine, transparent, structureless membrane,
containing a watery fluid, in which are occasionally found a few granules. It is
about 730- of an incn in diameter, and, in immature ova, lies nearly in the centre
of the yelk ; but, as the ovum becomes developed, it approaches the surface, and
enlarges much less rapidly than the yelk.
The germinal spot occupies that part of the periphery of the germinal vesicle
which is nearest to the periphery of the yelk. It is opaque, of a yellow color,
and finely-granular in structure, measuring from si^s to 54VTT of an inch.
The formation, development, and maturation of the Graafian vesicles and ova
continue uninterruptedly from infancy to the end of the fruitful period of
woman's life. Before puberty, the ovaries are small, the Graafian vesicles con-
tained in them minute, and few in number ; and few, probably, ever attain full
development, but shrink and disappear, their ova being incapable of impregnation.
At puberty, the ovaries enlarge, are more vascular, the Graafian vesicles are
developed in greater abundance, and their ova 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 from thence into the
Fallopian tube, the fimbriated processes of which are supposed to grasp the ovary,
the aperture of the tube being applied to the part corresponding to the matured
and bursting vesicle. In the human subject, and most mammalia, the maturation
and discharge of ova occur at regular periods only, and are indicated, in the mam-
malia, by the phenomena of heat or rut; and, in the human female, by menstruation.
Sexual desire is more intense in females at this period, and, if the union of the
sexes takes place, the ovum may be fecundated.
Corpus Luteum. Immediately after the rupture of a Graafian vesicle, and the
escape of its ovum, the vesicle is filled with blood-tinged fluid ; and in a short
time the circumference of the vesicle is occupied by a firm, yellow substance,
which is probably formed from plasma exuded from its walls. Dr. Lee believes
CORPUS LUTEUM. ?55
that this yellow matter is deposited outside both the membranes of the follicle ;
Montgomery regards it as placed between the layers; while Kolliker considers it
MB a thickening of the inner layer of the outer coat of the follicle. The exudation
is at first of a dark brown or brownish-red color, but it soon becomes paler, and
its consistence more dense.
For every follicle in the ovary from which an ovum is discharged, a corpus
luteum will be found. But the characters it exhibits, and the changes produced
in it, will be determined by the circumstance of the ovum being impregnated
or not.
Although there is little doubt of corpora lutea existing in the ovaries after the
escape of ova, independent of coitus, or impregnation, it appears that the corpus
luteum of pregnancy (true corpora lutea) possesses characters by which it may be
distinguished from one formed in a follicle, from which an ovum has been dis-
charged without subsequent impregnation (false corpora lutea).
The true corpora lutea are of large size, often as large as a mulberry ; of a
rounded form, and project from the surface of the ovary, the summit of the pro-
jection presenting a triangular depression or cicatrix, where the peritoneum
appears to have been torn. They contain a small cavity in their centre during the
early period of their formation, which becomes contracted, and exhibits a stellate
cicatrix during the latter stages of pregnancy. Its vascularity, lobulated or
puckered appearance, its firm consistence, and yellow color, are also characteristic
marks.
False corpora lutea are of small size, do not project from the surface of the
ovary, are angular in form, seldom present any cicatrix, contain no cavity in their
centre ; the material composing it is not lobulated, its consistence is usually soft,
often resembling coagulated blood ; the yellow matter exists in the form of a very
thin layer, or, more commonly, is entirely wanting. False corpora lutea most
frequently result from the effusion of serum or blood into the cavities of the
Graafian vesicles, which subsequently undergo various changes, and is ultimately
removed. Dr. Lee states, that in the false corpora lutea the yellow substance is
contained within, or attached to, the inner surface of the Graafian vesicle, and
does not surround it, as is the case in the true corpora lutea.
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 Ligament of the Ovary is a rounded cord, which extends from each superior
angle of the uterus to the inner extremity of the ovary ; it consists of fibrous
tissue, and a few muscular fibres derived from the uterus.
The Round Ligaments are two rounded cords, between four and five inches in
length, situated between the layers of the broad ligament, in front of and below
the Fallopian tube. Commencing on each side at the superior angle of the uterus,
each ligament passes forwards and outwards through the internal abdominal ring,
along the inguinal canal to the labia majora, in which it becomes lost. Each liga-
ment consists of areolar tissue, vessels, and nerves, besides a dense bundle of fibrous
tissue, and muscular fibres prolonged from the uterus, inclosed 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 obliterated in the adult, but sometimes remains pervious even in
advanced life. It is analogous to the peritoneal pouch which accompanies the
descent of the testes.
Vessels and Nerves. The arteries of the ovaries and Fallopian tubes are the
ovarian from the aorta. They anastomose with the termination of the uterine
arteries, and enter the attached border of the ovary. The veins follow the course
of the arteries ; they form a plexus near the ovary, the pampiniform plexus.
The nerves are derived from the spermatic plexus, the Fallopian tube receiving a
branch from one of the uterine nerves.
15G FEMALE ORGANS OF GENERATION.
Mammary Glands.
The Mammas or breasts are accessory glands of the generative system, which
secrete the milk. They exist in the male as well as in the female ; but in the
former only in a rudimentary state, unless their growth is excited by peculiar
circumstances. They are two large hemispherical eminences, situated towards
the lateral aspect of the pectoral region, corresponding to the interval between
the third and sixth or seventh ribs, and extending from the side of the sternum
to the axilla. Their weight and dimensions differ at different periods of life, and
in different individuals. Before puberty they are of small size, but enlarge as
the generative organs become more completely developed. They increase during
pregnancy, and especially after delivery, and become atrophied in old age. The
left mamma is generally a little larger than the right. Their base is nearly
circular, flattened or slightly concave, and having their long diameter directed
upwards and outwards towards the axilla ; they are separated from the Pectoral
muscles by a thin layer of superficial fascia. The outer surface of the mamma is
convex, and presents, just below the centre, a small conical prominence, the
mammilla or nipple. The surface of the nipple is dark-colored, and surrounded
by an areola having a colored tint. In the virgin, the areola is of a delicate
rosy hue ; about the second month of impregnation, it enlarges, and acquires a
darker tinge, which increases as pregnancy advances, becoming, in some cases,
a dark brown or even black color. This color diminishes as soon as lactation
is oyer, but is never entirely lost through life. These changes in the color of the
areola are of extreme importance in forming a conclusion in a case of suspected
pregnancy.
The nijjple is a cylindrical or conical eminence, capable of undergoing a sort of
erection from mechanical excitement. It is of a pink or brownish hue, its surface
wrinkled and provided with papillae, and its summit perforated by numerous
orifices, the apertures of the lactiferous ducts. Near the base of the nipple, and
upon the surface of the areola, are numerous sebaceous glands, which become much
enlarged during lactation, and present the appearance of small tubercles beneath
the skin. These glands secrete a peculiar fatty substance, which serves as a pro-
tection to the integument of the nipple in the act of sucking. The nipple consists
of numerous vessels, which form a kind of erectile tissue, intermixed with plain
muscular fibres.
Structure. The mamma consists of gland tissue ; of fibrous tissue, connecting
its lobes ; and of fatty tissue in the intervals between the lobes. The mammary
gland, free from cellular tissue and fat, is of a pale reddish color, firm in texture,
circular in form, flattened from before backwards, thicker in the centre than at
the circumference, and presenting several inequalities on its surface, especially in
front. It consists of numerous lobes, and these are composed of lobules, connected
together by areolar tissue, bloodvessels, and ducts. The smallest lobules consist
of a cluster of rounded vesicles, which open into the smallest branches of the
lactiferous ducts ; these ducts, uniting, form larger ducts, which terminate in a
single canal, corresponding with one of the chief subdivisions of the gland. The
number of excretory ducts vceries from fifteen to twenty ; they are termed the
tubuli lactiferi seu galactophori. They converge towards the areola, beneath which
they form dilatations or ampullae, which serve as reservoirs for the milk, and, at
the base of the nipple, become contracted, and pursue a straight course to its
summit, perforating it by separate orifices considerably narrower than the ducts
themselves. The ducts are composed of areolar tissue, with longitudinal and
transverse elastic fibres, and longitudinal muscular fibres; their mucous lining is
continuous, at the point of the nipple, with the integument; its epithelial lining is
of the tessellated or scaly variety.
The fibrous tissue invests the entire surface of the breast, and sends down septa
between its lobes, connecting them together.
MAMMARY GLANDS. 757
The fatty tissue surrounds the surface of the gland, and occupies the intervals
between its lobes and lobules. It usually exists in considerable abundance, and
determines the form and size of the gland. There is no fat immediately beneath
the areola and nipple.
Vessels and Nerves. The arteries supplying the mammas are derived from the
thoracic branches of the axillary, the intercostals, and internal mammary. The
veins describe an anastomotic circle round the base of the nipple, called, by Haller,
the circulus venosus. From this, large branches transmit the blood, to the cir-
cumference of the gland, and end in the axillary and internal mammary veins.
The lymphatics run along the lower border of the Pectoralis major to the axillary
glands. The nerves are derived from the anterior and lateral cutaneous nerves of
the thorax.
The Surgical Anatomy of Inguinal Hernia.
Dissection (fig. 380). For the 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 prone posi-
tion, the abdomen and pelvis raised by means of blocks placed beneath them, and the lower
extremities rotated outwards, so as to make the parts as tense as possible. If the abdominal
walls are flaccid, the cavity of the abdomen should be inflated by an aperture through the umbi-
licus. An incision should be made along the middle line, from the umbilicus to the pubes, 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 downwards and outwards, when
the superficial fascia will be exposed.
The superficial fascia in this region consists of two layers, .between which are
found the superficial vessels and nerves, and the inguinal lymphatic glands.
The superficial layer 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. This fascia is continued as a tubular prolongation around
the outer surface of the cord and testis. In this situation, it changes its character ;
it becomes thin, destitute of adipose tissue, and of a pale reddish color, and
assists in forming the dartos. From the scrotum, it may be traced backwards to
be continuous with the superficial fascia of the perineum. This layer should be
removed, by dividing it across in the same direction as the external incision, and
reflecting it downwards and outwards, when the following vessels and nerves will
be exposed: —
The superficial epigastric, circumflex iliac, and external pudic vessels ; the ter-
minal filaments of the ilio-hypogastric and ilio-inguinal nerves ; and the upper
chain of inguinal lymphatic glands.
The superficial epigastric artery crosses Poupart's ligament, and ascends obliquely
towards the * umbilicus, lying midway between the spine of the ilium and the
pubes. It supplies the integument, and anastomoses with the deep epigastric.
This vessel is a branch of the common femoral artery, and pierces the fascia lata,
below Poupart's ligament. Its accompanying vein empties itself into the internal
saphenous, piercing previously the cribriform fascia.
The superficial external pudic artery passes transversely inwards across the
spermatic cord, and supplies the integument of the hypogastric region, and of the
penis and scrotum. This vessel is usually divided in the first incision made in the
operation for inguinal hernia, and occasionally requires the application of a ligature
to suppress the hemorrhage.
The circumflex iliac artery passes outwards towards the crest of the ilium. The
veins accompanying the latter vessels are usually much larger than the arteries ;
they terminate in the internal saphenous vein.
Lymphatic vessels are found, taking the same course as the bloodvessels ; they
return the lymph from the superficial structures in the lower part of the abdomeu,
the scrotum, penis, and external surface of the buttock, and terminate in a small
chain of lymphatic glands, three or four in number, which lie on a level with,
Poupart's ligament.
Nerves. The terminal branch of the ilio-inguinal nerve emerges at the external
abdominal ring ; and the hypogastric branch of the ilio-hypogastric nerve perfo-
rates the aponeurosis of the external oblique above and to the outer side of the
external ring.
The Deep layer of superficial fascia should be divided across in the same
758
INGUINAL HERNIA— SUPERFICIAL DISSECTION. 759
direction as the external incisions, separated from the aponeurosis of the External
oblique, to which it is connected by delicate areolar tissue, and reflected down-
wards and outwards. It is thin, aponeurotic in structure, and of considerable
strength. It is intimately adherent, in the middle line, to the linea alba, and,
below, to the whole length of Poupart's ligament and upper part of the fascia
lata. It forms a thin tubular prolongation round the outer surface of the cord,
which blends with the superficial layer, and is continuous with the dartos of the
scrotum. From the back of the scrotum, the conjoined layers maybe traced into
the perineum, where they are continuous with the deep layer of the superficial
fascia in this region, which is attached, behind, to the triangular ligament, and, on
each side, to the ramus of the pubes and ischium. The connections of this fascia
serve to explain the course taken by the urine in extravasation of this fluid from
rapture of the urethra ; passing forwards from the perineum into the scrotum,
it ascends on to the abdomen, but is prevented extending into the thighs by the
attachment of the fascia to the ramus of the pubes and ischium, on each side, and
to Poupart's ligament in front.
Fig. 380. — Inguinal Hernia. Superficial Dissection.
Exttmnl
AbUomiaalRing
The aponeurosis of the External oblique muscle is exposed on the removal of thi3
fascia. It is a thin, strong, membranous aponeurosis, the fibres of which are
directed obliquely downwards and inwards. It is attached to the anterior superior
spinous process of the ilium, the spine of the pubes, the pectineal line, front of the
pubes, and linea alba. That portion of the aponeurosis which extends from the
7G0 SURGICAL ANATOMY OF INGUINAL HERNIA.
anterior superior spine of the ilium, to the spine of the pubes, is termed Poupart's
ligament or the crural arch ; and that portion which is inserted into the pectineal
line, is termed Gimbernat's ligament.
Just above and to the outer side of the crest of the pubes, a triangular interval
is seen in the aponeurosis of the External oblique, called the external abdominal
ring ; it transmits the spermatic cord in the male, and the round ligament in the
female. 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 inter columnar, which pass across the upper angle of the ring so as to increase
its strength ; and on either side, by the free borders of the aponeurosis, which are
called the columns or pillars of the ring.
The external pillar, which, at the same time, is inferior from the obliquity of
its direction, is the strongest ; it is formed by that portion of Poupart's ligament,
which is inserted into the spine of the pubes ; it is curved round the spermatic
cord, so as to form a kind of groove, upon which it rests.
The internal or superior pillar is a broad, thin, flat band, which interlaces 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 women on
account of the large size of the spermatic cord, and hence the greater frequency
of inguinal hernia in the former sex.
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; they increase the strength of the membrane which bounds the upper part
of this aperture, and prevent the divergence of the pillars from one another. They
are thickest below, where they are connected to the outer third of Poupart's
ligament, and taking a curvilinear course, the convexity of which is directed
downwards, are inserted into the linea alba. 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 fibres are continuous with a thin
fascia, which is closely connected to the margins of the external ring, and has
received the name of the intercolumnar or external spermatic fascia ; it forms a
tubular prolongation around the outer surface of the cord and testis, and incloses
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.
The finger should be introduced a slight distance into the external ring, and, if
the limb is extended and rotated outwards, 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 inwards, this aponeurosis will become lax~ and the external
ring sufficiently enlarged to admit the finger with comparative ease ; hence the
latter position should always be assumed in cases where the taxis is applied for
the reduction of an inguinal hernia, in order that the abdominal walls may be as
much relaxed 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 outwards ; 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. 381). The mode of insertion of Poupart's and Gimbernat's ligaments into the pubes should
also be examined.
Poupart's ligament or the crural arch extends from the anterior superior spine
of the ilium to the spine of the pubes. It is also attached to the pectineal line
to the extent of about an inch, forming Gimbernat's ligament. Its general
INTERNAL OBLIQUE — CREM ASTER.
761
direction is curved towards the thigh, where it is continuous with the fascia lata.
Its outer half is rounded, oblique in its direction, and continuous with the iliac
fascia. Its inner half gradually widens at its attachment to the pubes, is more
horizontal in direction, and lies beneath the spermatic cord.
&imbernai's ligament is that portion of the aponeurosis of the External oblique
which is inserted into the pectineal line; it is thin, membranous in structure,
triangular in shape, the base directed outwards, and passes upwards and backwards
beneath the spermatic cord, from the spine of the os pubis to the pectineal line, to
the extent of about half an inch.
The triangular ligament is a band of tendinous fibres, of a triangular shape,
which is continued from Poupart's ligament at its attachment to the pectineal line
upwards and inwards, beneath the inner pillar of the external ring, to the linea
alba.
The Internal oblique muscle has already been described (p. 283). The part which
is now exposed is partly muscular and partly tendinous in structure. Those fibres
which arise from the outer part of Poupart's ligament are thin, pale in color,
curve downwards, and terminate in an aponeurosis, which passes in front of the
Rectus and Pyramidalis muscles, to be inserted into the crest of the os pubis and
Fig. 3S1.-
-Inguinal Hernia, showing the Internal Oblique,
Cremaster, and Spermatic Canal.
f\
pectineal line, to the extent of half an inch, in common with that of the Trans,
versalis muscle, forming by their junction the conjoined tendon. This tendon is
placed immediately behind Gimbernat's ligament and the external abdominal ring,
and serves to strengthen what would otherwise be a very weak point in the
abdominal wall. When the pouch of inguinal hernia passes directly through the
external ring, forming what is called direct inguinal hernia, the conjoined tendon
usually forms one of its coverings.
The Cremaster is a slender muscular fasciculus, which arises from the middle of
162 SURGICAL ANATOMY OF INGUINAL HERNIA.
Poupart's ligament at the inner side of the Internal oblique, being connected with
that muscle, and also occasionally with the Transversalis. It passes along the
outer side of the spermatic cord, descends with it through the external ring upon
the front and sides of the cord, and forms a series of loops, which differ in thick-
ness and length in different subjects. 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, the fascia cremasterica. 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.
It will be observed, that the origin and insertion of the Cremaster are precisely
similar with those 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 towards 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 circum-
stances, 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?.
No such muscle exists in the female, but an analogous structure is developed in
those cases where an oblique inguinal heimia 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 inwards on to the sheath of
the Rectus (fig. 385). The circumflexa ilii vessels, which lie between these two muscles, form a
valuable guide to their separation.
The Transversalis muscle has been previously described (p. 284). Its lower part
is partly fleshy and partly tendinous in structure ; this portion arises from the
outer third of Poupart's ligament, and arching downwards and inwards over the
cord, terminates in an aponeurosis, which is inserted into the linea alba, the crest
of the pubes, and into the pectineal line to the extent of an inch, forming together
with the Internal oblique, the conjoined tendon. Between the lower border of
this muscle and Poupart's ligament, a space is left in which is seen the fascia
transversalis.
The inguinal or spermatic canal 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 downwards and inwards, and placed parallel with, and
a little above, Poupart's ligament. It communicates, above, with the cavity of
the abdomen, by means of the internal 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, the superficial fascia, and by the apo-
neurosis of the External oblique throughout its whole length, and by the Internal
oblique for its outer third ; behind, by the conjoined tendon of the Internal
oblique and Transversalis, the triangular ligament, transversalis fascia, and the
sub-peritoneal fat and peritoneum ; above, by the arched fibres of the Internal
oblique and Transversalis ; below, by the union of the fascia transversalis with
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.
SPERMATIC CANAL — INTERNAL RING.
763
The fascia transversalis is a thin aponeurotic membrane, 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 ; 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
these vessels it is thin, and attached to the pubes 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.
Fig. 382.-
-Inguinal Hernia, showing the Transversalis Muscle, the Transversalis Fascia, and the
Internal Abdominal Ring.
The Internal Abdominal ring is situated in the transversalis fascia, midway
between the anterior superior spine of the ilium and the spine of the pubes, and
about half an inch above Poupart's ligament. It is of an oval form, the extremi-
ties of the oval directed upwards and downwards, varies in size in different
subjects, and is much larger in the male than the female. It is bounded, above,
by the arched fibres of the Transversalis muscle, and, internally, by the epigastric
vessels. It transmits the spermatic cord in the male, and the round ligament in
the female; and from its circumference, a thin, funnel-shaped membrane, the
infundibuliform or transversalis fascia is continued round the cord and testis,
inclosing them in a distinct pouch. When the sac of an oblique inguinal hernia
passes through the internal ring, the transversalis fascia forms one of its
coverings.
Bet-ween the transversalis fascia and the peritoneum is a quantitv of loose
areolar tissue. In some subjects it is of considerable thickness, and loaded with
?64 SURGICAL ANATOMY OF INGUINAL HERNIA.
adipose tissue. Opposite the internal ring it is continued round the surface of
the cord, forming for it a loose sheath.
The epigastric artery bears a very important relation to the internal abdominal
ring. This vessel lies between the transversalis fascia and peritoneum, and passes
obliquely upwards and inwards, from its origin from the external iliac, to the
margin of the sheath of the Rectus muscle. In this course, it lies along the lower
and inner margin of the internal ring, and beneath the commencement of the
spermatic cord, the vas deferens curving round it as it passes from the ring into
the pelvis.
The peritoneum, corresponding to the inner surface of the internal ring, pre-
sents 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. This is the remains of the pouch of
peritoneum which, in the foetus, accompanies 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 only closed 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.
Inguinal Hernia.
Inguinal Hernia includes 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 most frequent of the two, is that form
of jjrotrusion which 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 epigastric
artery.
Internal or direct inguinal hernia is that form of protrusion which does not
follow the same course as the cord, but protrudes through the abdominal wall on
the inner or pubic side of the epigastric artery.
Oblique Inguinal Hernia.
In Oblique Inguinal Hernia, the intestine escapes from the abdominal cavity at
the internal ring, pushing before it a pouch of peritoneum, which forms the hernial
sac. As it enters the inguinal canal, it receives an investment from the subserous
areolar tissue, and is inclosed in the infundibuliform process of the transversalis
fascia. In passing along the inguinal canal, it displaces upwards the arched fibres
of the Transversalis and Internal oblique muscles, and is surrounded by the fibres
of the Cremaster. It then passes along the front of the cord, and escapes from
the inguinal canal at the external ring, receiving an investment from the inter-
columnar fascia. Lastly, it descends into the scrotum, receiving coverings from
the superficial fascia and the integument.
The various coverings of this form of hernia, after it has passed through the
external ring, are, from without inwards, the integument, superficial fascia, inter-
columnar fascia, Cremaster muscle, transversalis fascia, subserous cellular 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 adhesions of the cover-
ings of the cord to the tunica vaginalis.
The seat of stricture in oblique inguinal hernia is either at the external ring, in
the inguinal canal, caused by the fibres of the Internal oblique or Transversalis,
VARIETIES OF INGUINAL HERNIA. T65
or at the internal ring ; more frequently in the latter situation. If it is situated at
the external ring, the division of a few fibres at one point of its circumferenee is
all that is necessary for the replacement of the hernia. If in the inguinal canal,
or at the internal ring, it will be necessary to divide the aponeurosis of the Ex-
ternal oblique so as to lay open the inguinal canal. In dividing the stricture,
the direction of the incision should be directly upwards.
When the intestine passes along the spermatic canal, and escapes from the
external ring into the scrotum, it is called common oblique inguinal or scrotal hernia.
If the intestine does not escape from the external ring, but is retained in the
inguinal canal, it is called incomplete inguinal hernia or bubonocele. In each of
these cases, the coverings which invest it will depend upon the extent to which
it descends in the inguinal canal.
There are two other varieties of oblique inguinal hernia : — the congenital and
infantile.
Congenital hernia is liable to occur in those cases where the pouch of perito-
neum which accompanies the cord and testis in its descent in the foetus remains
unclosed, and communicates directly with the peritoneum. The intestine descends
along this pouch into the cavity of the tunica vaginalis, and lies in contact with
the testis. This form of hernia has no proper sac, being contained within the
tunica vaginalis.
In infantile hernia, the hernial sac descends along the inguinal canal into the
scrotum, behind the pouch of peritoneum which accompanies the cord and testis
into the same part. The abdominal aperture of this pouch is closed, but the
portion contained in the inguinal canal remains unobliterated. The hernial sac
is consequently invested, more or less completely, by the posterior layer of the
tunica vaginalis, from which it is separated by a little loose areolar tissue ; so that
in operating upon this variety of hernia, three layers of peritoneum would require
division, the first and second being the layers of the tunica vaginalis, the third
the anterior layer of the hernial sac.
Dieect Inguinal Hernia.
In Direct Inguinal Hernia, the protrusion makes its way through some part of
the abdominal wall internal to the epigastric artery, and passes directly through
the abdominal parietes and external ring. At the lower part of the abdominal
wall is a triangular space (Hesselbach's triangle), bounded, externally, by the
epigastric artery; internally, by the margin of the Rectus muscle; below, by
Poupart's ligament. The conjoined tendon is stretched across the inner two-
thirds of this space, the remaining portion of the space being filled in by the
transversalis fascia.
In some cases [more often, perhaps, than is generally supposed], the hernial
protrusion escapes from the abdomen on the outer side of the conjoined tendon,
pushing before it the peritoneum, the subserous cellular tissue, and the transver-
salis 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 of protrusion.
In other cases, and this is the more frequent variety, the intestine is either
forced through the fibres of the conjoined tendon, or the tendon is gradually dis-
tended in 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 super-
ficial 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 part of the general
fascia transversalis.
The seat of stricture in both varieties of direct hernia is most frequently at the
T66 SURGICAL ANATOMY OF FEMORAL HERNIA.
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 upwards.
If the hernial protrusion passes into the inguinal canal, but does not escape
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, very diffi-
cult 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 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 pro-
gress by the transversalis fascia and conjoined tendon. It differs also in its posi-
tion, being placed over the pubes, and not in the course of the inguinal canal.
The epigastric artery runs along 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
tin oblique inguinal hernia.
SURGICAL ANATOMY OF FEMORAL HERNIA.
Dissection (fig. 383). 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 its back ; a block is first placed under the pelvis, the thigh everted, and the knee 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 connected together by a vertical one carried along the inner side of the thigh.
These several incisions should divide merely the integument ; this is to be reflected outwards,
when the superficial fascia will be exposed.
The superficial fascia at the upper part of the thigh consists of two layers,
between which are found the cutaneous vessels and nerves, and numerous lym-
phatic glands.
The superficial layer is a thick and dense cellulo-fibrous membrane, in the meshes
of which is found a considerable amount of adipose tissue, which varies in quantity
in different subjects ; this layer may be traced upwards over Poupart's ligament
to be continuous with the superficial fascia of the abdomen ; whilst below, and on
the inner and outer sides of the limb, it is continuous with the superficial fascia
covering the rest of the thigh.
This 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 this vessel and its branches ; it should then be reflected outwards,
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 superficial fascia. These are
the internal saphenous vein, and the superficial epigastric, superficial circumflexa ilii, and super-
ficial pudic vessels, as well as numerous lymphatics ascending with the saphenous vein to the
inguinal glands.
The internal saphenous vein i's a vessel of considerable size, which ascends obliquely
upwards along the inner side of the thigh, below Poupart's ligament. It passes
through the saphenous opening in the fascia lata to terminate in the femoral vein.
This vessel is accompanied by numerous lymphatics, which return the lymph
from the dorsum of the foot and inner side of the leg and thigh ; they terminate
in the inguinal glands, which surround the saphenous opening. Converging
towards the same point are the superficial epigastric vessels, which run across
Pou part's ligament, obliquely upwards and inwards, to the lower part of the
FEMORAL HERNIA — SUPERFICIAL DISSECTION. T6>
abdomen ; the circumflexa ilii vessels pass obliquely outwards along Poupart's
ligament to the crest of the ilium ; and the superficial external pudic vessels pass
inwards to the perineal and scrotal regions. These vessels supply the subcutaneous
areolar tissue and the integument, and are accompanied by numerous lymphatic
vessels, which return the lymph from the same parts to the inguinal glands.
" The superficial inguinal glands are arranged in two groups, one of which is
disposed parallel with Poupart's ligament ; the other is placed below this ligament,
surrounding the termination of the saphenous vein, and following (occasionally)
the course of this vessel a short distance along the thigh. The upper chain
receives the lymphatic vessels from the penis, scrotum, lower part of the abdomen,
perineum, and buttock ; the lower chain receives the lymphatic vessels from the
lower extremity.
The nerves supplying the integument of this region are derived from the ilio-
Fig. 383.— Femoral Hernia. Superficial Dissection.
inguinal, the genito-crural, and anterior crural. The ilio-inguinal nerve may be
found on the inner side of the internal saphenous vein, the terminal branch of the
genito-crural nerve outside the vein, and the middle and external cutaneous nerves
more external.
The deep layer of superficial fascia should be divided in the same direction
as the external incisions, and separated from the fascia lata ; this is easily effected,
from its extreme thinness. It is a thin but dense membrane, placed beneath the
subcutaneous vessels and nerves, and upon the surface of the fascia lata. It is
768
SURGICAL ANATOMY OF FEMORAL HERNIA.
intimately adherent above to the lower margin of Poupart's ligament, and about
one inch below this ligament covers the saphenous opening in the fascia lata,
is closely united to its circumference, and is connected to the sheath of the
femoral vessels corresponding to its under surface. The portion of fascia covering
this aperture is perforated by the internal saphenous vein, and by numerous blood-
vessels and lymphatics ; hence it has been termed, from its sieve-like appearance,
the cribriform fascia. A femoral hernia, in passing through the saphenous open-
ing, receives the cribriform fascia as one of its coverings.
The deep layer of superficial fascia, together with the cribriform fascia, having
been removed, the fascia lata is exposed.
The Fascia Lata, already described (p. 328), is a dense fibrous aponeurosis,
which forms a uniform investment for the whole of this region of the limb. At
the upper and inner part of the thigh, a large oval-shaped aperture is observed in
it ; it transmits the internal saphenous vein and other small vessels, and is called
the saphenous opening. In order the more correctly to consider the mode of
Fig. 3S4.— Femoral Hernia, showing Fascia Lata and Saphenous Opening.
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.
The iliac portion of the fascia lata is situated on the outer side of the saphenous
opening, covering the outer surface of the Sartorius, the Rectus, and the Psoas
and Iliacus muscles. 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 pubes, and to the pectineal line in conjunction with Gimber-
FASCIA LATA— SAPHENOUS OPENING. T69
nat's ligament, where it becomes continuous with the pubic portion. From the
spine of the pubes, it is reflected downwards and outwards, forming an arched
margin, the outer boundary {superior cornu) of the saphenous opening. This is
sometimes called the falciform process of the fascia lata or femoral ligament of
Hey ; it overlies, and is adherent to the sheath of the femoral vessels beneath ;
to its edge is attached the cribriform fascia, and it is continuous below with' th.e
pubic portion of the fascia lata by a well-defined curved margin.
The pubic portion of the fascia lata is situated at the inner side of the saphe-
nous opening ; at the lower margin of this aperture, it is continuous with the iliac
portion ; traced upwards, it 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 continuous with the sheath of the Psoas and Iliacus
muscles, and is finally lost in the fibrous capsule of the hip-joint. This fascia is
attached above to the pectineal line, and internally to the margin of the pubic
arch. It may be observed from this description, that the iliac portion of the
fascia lata passes in front of the femoral vessels, the pubic portion behind them ;
an apparent aperture consequently exists between the two, through which the
internal saphenous joins the femoral vein.
The Saphenous Opening 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 part of the thigh, below Poupart's ligament, on the pubic side of its centre,
and is directed obliquely downwards and outwards.
Its outer margin 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
upwards, it will be seen to form a curved elongated process or cornu, the superior
cornu ox falciform process of Burns, which ascends in front of the femoral vessels,
and curving inwards is attached to Poupart's ligament and to the spine of the
pubis and pectineal line, where it is continuous with the pubic portion. If traced
downwards, it is found continuous with another curved margin, the concavity of
which is directed upwards and inwards ; 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 doundary of the opening 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 crural 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 outwards, and to be relaxed on flexing the limb
and inverting it : hence the necessity of 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, together with its falciform process, should now be removed,
by detaching it from, the lower margin of Poupart's ligament, carefully dissecting it from the
subjacent structures, and turning it aside, when the sheath of the femoral vessels is exposed
descending beneath Poupart's ligament (fig. 385).
The Crural Arch or PouparCs Ligament is the lower border of the aponeurosis
of the External oblique muscle, which stretches across between the anterior supe-
rior spine of the ilium to the spine of the os pubis and pectineal line ; the portion
corresponding to the latter insertion is called Gimbernafs ligament. Its direction
is curved downwards towards the thigh ; its outer half being oblique, its inner half
nearly horizontal. Nearly the whole of the space included between the crural
arch and innominate bone is filled in by the parts which descend from the abdo-
men into the thigh. The outer half of this space is occupied by the Iliacus and
Psoas muscles, together with the external cutaneous and anterior crural nerves.
The pubic side of the space is occupied by the femoral vessels included in their
49
no
SURGICAL ANATOMY OF FEMORAL HERNIA.
sheath, a small oval-shaped interval existing between the femoral vein and the
inner wall of the sheath, which is occupied merely by a little loose areolar tissue,
and occasionally a small lymphatic gland ; this is the crural canal, along which a
portion of gut descends in femoral hernia.
Qimbernais Ligament (fig. 386) is that part of the aponeurosis of the External
oblique muscle, which is reflected downwards and outwards to be inserted into
the pectineal line of the os pubis. It is about 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, the base directed outwards. Its base or outer margin is
concave, thin and sharp, lies in contact with the crural sheath, and is blended with
the pubic portion of the fascia lata. Its apex corresponds to the spine of the pubes.
Its posterior margin is attached to the pectineal line. Its anterior margin is con-
tinuous with Poupart's ligament.
Fig. 385. — Femoral Hernia ; Iliac Portion of Fascia Lata having been removed, and
Sheath of Femoral Vessels and Femoral Canal exposed.
Crural Sheath. If Poupart's ligament is divided, the femoral or crural sheath
may be demonstrated as a continuation downwards 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 this vessel,
which constitutes the femoral or crural canal. The femoral sheath is closely
CRURAL CANAL— FEMORAL RING. Ill
adherent to the contained vessels about an inch below the saphenous opening,
becoming 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 is perforated by
the genito-crural 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.
Deep Crural Arch. Passing across the front of the crural sheath, and closely
connected with it, is a thickened band of fibres, called the deep crural arch. It
is apparently a thickening of the fascia transversalis, joined 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
unfrequently it is altogether wanting.
If the anterior wall of the sheath is removed, the femoral artery and vein are
seen lying side by side, a thin septum separating the two vessels, and another
septum separating the vein from the inner wall of the sheath ; the septa are stretched
between the anterior and posterior walls of the sheath, so that each vessel is
inclosed 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 a lymphatic gland ; this
is the femoral or crural canal, through which a portion of intestine descends in
femoral hernia.
The crural canal is the narrow interval between the femoral vein and the inner
wall of the crural sheath. Its length is from a quarter to half an inch, and it
extends from Gimbernat's ligament to the upper part of the saphenous opening.
Its anterior wall is very narrow, and formed by the fascia transversalis, Pou-
part's ligament, and the falciform process of the fascia lata.
Its posterior wall is formed by the iliac fascia and the pubic portion of the
fascia lata.
Its outer wall is formed by the fibrous septum covering the inner side of the
femoral vein.
Its inner wall is formed by the junction of the transversalis and iliac fasciae,
which forms the inner side of the femoral sheath and covers the outer edge of
Gimbernat's ligament.
This canal has two orifices : a lower one, the saphenous opening, closed by the
cribriform fascia; an upper one, the femoral or crural ring, closed by the septum
crurale.
The femoral or crural ring (fig. 386) 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 pubes, covered by the Pectineus
muscle, and the pubic portion of the fascia lata; internally, by Gimbernat's
ligament, the conjoined tendon, the transversalis fascia, and the deep crural arch ;
externally, by the femoral vein, covered by its sheath. 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 ; hence 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 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 epigastric artery, in its passage inwards from the external iliac to the
umbilicus, passes across the upper and outer angle of the crural rinjr, and is
consequently in great danger of being wounded if the stricture is divided in a
direction upwards and outwards.
772 -SURGICAL ANATOMY OP FEMORAL HERNIA.
The communicating branch between the 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. It is in the former position that the stric-
ture is divided in cases of strangulated femoral hernia.
Fig. 3S(5. — Hernia. The Relations of the Femoral and Internal Abdominal Rings,
seen from within the Abdomen. Right Side.
The obturator artery, when it arises by a common trunk with the epigastric,
which occurs once in every three subjects and a half, bears a very important
relation to the crural ring. In some cases (fig. 387) it descends on the 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 little danger of its being wounded
in the operation for dividing the stricture in femoral hernia. Occasionally, how-
Variations in Origin and Course of Obturator Artery.
Fig. 387. Fig. 388.
ever, this vessel curves along the free margin of Gimbernat's ligament in its
passage to the obturator foramen ; it would, consequently, skirt along the greater
part of the circumference of the crural canal, and could hardly fail in being
wounded in the operation (fig. 388).
Septum Crurale. The femoral ring is closed by a layer of condensed areolar
tissue, 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,
DESCENT AND COVERINGS OF FEMORAL HERNIA. 773
and supports a small lymphatic gland, by which it is separated from the subserous
areolar tissue and peritoneum. Its under surface is turned towards the femoral
canal. The septum crurale is perforated by numerous apertures for the passage
of lymphatic vessels, connecting the deep inguinal glands with those surrounding
the external iliac artery.
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 extremely tense from the traction on these parts by
Poupart's ligament and the fascia lata, as may be ascertained by passing the
finger along it. If, on the contrary, the thigh is flexed upon the pelvis, and, at
the same time, adducted and rotated inwards, 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 septum crurale is separated from the peritoneum by a quantity of loose
subserous areolar tissue. In some subjects this tissue contains a considerable
amount of adipose substance, which, when protruded forwards in front of the sac
of a femoral hernia, may be mistaken for a portion of omentum.
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 larger
size of this aperture in the female serves to explain the frequency of this form
of hernia in women.
When a portion of intestine is forced through the femoral ring, it carries before
it a pouch of peritoneum, which forms what is called the hernial sac ; it receives
an investment from the subserous areolar tissue, and 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 extending further down the sheath, on account of its
greater narrowness and 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 ; it is, consequently, directed forwards,
pushing before it the cribriform fascia, and curves upwards 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 downwards, then
forwards and upwards ; this should be borne in mind, as in the application of the
taxis for the reduction of a femoral hernia, pressure should be directed precisely
in the reverse order.
Coverings of the Hernia. The coverings of a femoral hernia from within out-
wards are peritoneum, subserous areolar tissue, the septum crurale, crural sheath,
cribriform fascia, superficial fascia, and integument.
Varieties of Femoral Hernia. If the intestine descends along the femoral canal
only as far as the saphenous opening, and does not escape from this aperture, it is
called incomplete femoral hernia. The small size of the protrusion in this form
of hernia, on account of the firm and resisting nature of the canal in which it is
contained, renders it an exceedingly dangerous variety of the disease, from the
extreme difficulty of detecting the existence of the swelling, especially in corpulent
subjects. The coverings of an incomplete femoral hernia would be, from without
inwards, integument, superficial fascia, falciform process of fascia lata, fascia
propria, septum crurale, subserous cellular tissue, and peritoneum. When, how-
ever, the hernial tumour protrudes through the saphenous opening, and directs
m SURGICAL ANATOMY OF FEMORAL HERNIA.
itself forwards and upwards, it forms a complete femoral hernia. 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 of a 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 a direction
upwards and inwards ; and the extent necessary 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.
Surgical Anatomy of the Perineum and
Ischio-Rectal Region.
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. 389, the scrotum should be raised upwards, and retained in
that position, and the rectum moderately distended with tow.
The space which is now exposed, corresponds to the inferior aperture or outlet
of the pelvis. Its deep boundaries are, in front, the pubic arch and sub-pubic
ligament ; behind, the tip of the coccyx ; and on each side, the ramus of the pubes
and ischium, the tuberosity of the ischium, and great sacro-sciatic ligament. The
space included by these boundaries is somewhat lozenge-shaped, and is limited on
the surface of the body by the scrotum in front, by the buttocks behind, and on
each side by the inner side of the thighs. It measures, from before backwards,
about four inches, and about three in the broadest part of its transverse diameter,
between the ischial tuberosities. A line drawn transversely between the anterior
part of the tuberosity of the ischium, on either side, in front of the anus, sub-
divides this space into two portions. The anterior portion contains the penis and
urethra, and is called the perineum. The posterior portion contains the termina-
tion of the rectum, and is called the ischio-rectal region.
Ischiorectal Kegiojst.
The Ischio-rectal region corresponds to the portion of the outlet of the pelvis
situated immediately behind the perineum: it contains the termination of the
rectum. A deep fossa, filled with fat, is seen on either side of the intestine,
between it and the tuberosity of the ischium: this is called the ischiol-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 distension of the intestine. The integument is of a dark color,
continuous with the mucous membrane of the rectum, and provided with numerous
follicles, which occasionally inflame and suppurate, and may be mistaken for
fistulas. 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. 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 round the margins of this aperture
to its posterior extremity, and continue it backwards 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 gut. 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 (figs. 389 — 392) should now be removed. In
dissecting the integument from this region, great care is required, otherwise the External sphincter
will be removed, as it is 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
775
TtG
SURGICAL ANATOMY OF THE PERINEUM.
two or three cutaneous branches of the small sciatic nerve ; these turn round the
inferior border of the Gluteus maximus, and are distributed to the integument
in this region.
Fig. 389. — Dissection of Perineum and Ischio-rectal Region.
The External sphincter is a thin flat plane of muscular fibres, elliptical in
shape, and intimately adherent 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 of the coccyx, by a narrow tendinous band, and from the superficial
fascia in front of that bone ; and is inserted into the tendinous centre of the
perineum, joining with the Trans versus perinei, and the other muscles inserted
into this part. Like other sphincter muscles, it consists of two planes of muscular
fibre, which surround the margin of the anus, and join at the commissure before
and behind.
Relations. By its superficial surface, with the integument ; by its deep surface it
is in contact with the Internal sphincter ; and is separated from the Levator ani
by loose areolar tissue.
The Sphincter ani is a voluntary muscle, supplied by the hemorrhoidal branch
of the fourth sacral nerve. This muscle is divided in the operation for fistula in
ano ; and also in some cases of fissure of the rectum, especially if attended with
much pain or spasm. The object of its division is to keep the parts at rest and
in contact during the healing process.
The Internal sphincter is a muscular ring, about half an inch in breadth, which
surrounds the lower extremity of the rectum, about an inch from the margin of
the anus. 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.
The Ischio-rectal Fossa is situated 'between the end of the rectum and the
tuberosity of the ischium on each side. It is triangular in shape, its base
directed to the surface is formed by the integument of the ischio-rectal region ; its
apex, directed upwards, 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 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 intern us muscle ; in front, it is
limited by the line of junction of the superficial and deep perineal fascia ; and
behind, by the margin of the Gluteus maximus, and the great sacro-sciatic
ISCHIO-RECTAL FOSSA— PERINEUM. m
ligament. This space is filled with a large mass of adipose substance, which
explains the frequency with which abscesses in the neighborhood 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 nerve, will be
felt about an inch and a half above the margin of the ischial tuberosity, but
approaching nearer the surface as they pass forwards along the inner margin of the
pubic arch. These structures are inclosed in a sheath formed by the obturator
fascia, the pudic nerve lying below the artery. Crossing the space transversely,
about its centre, are the inferior hemorrhoidal vessels and nerves, branches of the
pudic ; they 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 litho-
tomy, or for fistula in ano. At the back part of this space may be seen a branch
of the fourth sacral nerve ; and, at the fore part of the space, a cutaneous branch
of the perineal nerve.
Perineum.
The Perineal Space' is of a triangular form ; its deep boundaries are limited,
laterally, by the rami of the pubes and ischia, meeting in front at the pubic arch ;
behind, by an imaginary transverse line, extending between the tuberosity of the
ischium on either side. The lateral boundaries vary, 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 diameter 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 approximated,
it would be necessary to make the incisions in the lateral operation of lithotomy
much less oblique, than if the tuberosities were widely separated, and the perineal
space, consequently, wider. The perineum is subdivided by the median raphe
into two equal parts. Of these, the left is the one usually selected to commence
the primary incisions in the operation of lithotomy.
In the middle line, the perineum 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 flaps of integument corresponding to this space having been removed, in the
manner shown in figs. 388 — 391, the superficial fascia is exposed.
The Superficial Fascia consists of two layers, as in other regions of the body,
superficial and deep.
The superficial layer is thick, loose, areolar in texture, and 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. This layer should be
carefully removed, after it has been examined, when the deep layer will be
exposed.
The deep layer of superficial fascia (superficial perineal fascia) is thin, aponeu-
rotic 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 dartos of the scrotum ;
on either side, it is firmly attached to the margins of the rami of the pubes and
ischium, external to the crus penis, and as far back as the tuberosity of the
ischium ; posteriorly, it curves down behind the Transversus perinei muscles to
join the lower margin of the deep perineal fascia. This fascia not only covers the
muscles in this region, but sends down a vertical septum from its under surface
778
SURGICAL ANATOMY OF THE PERINEUM.
which, separates the back part of the subjacent space into two, being incomplete
in front.
In rupture of the anterior portion of the urethra, accompanied by extravasation
of urine, the fluid makes its way forwards, beneath this fascia, into the areolar
Fig. 390. — The Perineum : the Integument and Superficial Layer of
Superficial Fascia being reflected.
tissue of the scrotum, penis, and anterior and lateral portions of the abdomen ; it
rarely extends into the areolar tissue on the inner side of the thighs, or backwards
around the anus. This limitation of the extravasated fluid to the parts above-
named is easy of explanation, when the attachments of the deep layer of the
superficial fascia are considered. "When this fascia is removed, the muscles con-
nected with the penis and urethra will be exposed ; these are, in the middle line,
the Accelerator urinae ; on each side, the Erector penis ; and behind, the Trans-
versa perinei.
The Accelerator urinse is placed in the middle line of the perineum, immediately
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 of the perineum,
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 are lost on the
anterior surface of the triangular ligament ; the middle fibres encircle the bulb and
adjacent part of the corpus spongiosum, and join with the muscle of the opposite
side, on the upper part of this body, 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 this body, anterior to the Erector penis ; partly termi-
nating 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
"ft outwards from the surface of the urethra. .
Action. This muscle may serve to accelerate the flow of urine or semen
MUSCLES OF THE PERINEUM.
no
along the canal of the urethra. 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, according to Tyrrel, also contribute to the
erection of the penis, as they are inserted into, and continuous with, the fascia
penis, compressing the dorsal vein during the contraction of the muscle.
Fig. 391.— The Superficial Muscles and Vessels of the Perineum.
C-rT Saero Sriaiie Zigf-
Superficial Perineal A rttry
Superficia. I Perineal Aer ve
Internal Pudie Nerve
Infernal Pudic Arte ry
The Erector Penis covers the unattached 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 perineum. 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 pubes. From these points, fleshy fibres succeed, which end in an
aponeurosis which is inserted into the sides and under surface of the crus penis.
This muscle compresses the crus penis, and thus serves to maintain this organ
erect.
The Transversus Perinei 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 side of the ascending ramus of the ischium, and, passing
obliquely forwards and inwards, is inserted into the central tendinous point of the
perineum, joining in this situation with the muscle of the opposite side, the
Sphincter ani behind, and the Accelerator urinae in front.
Between the muscles just examined, a triangular space exists, bounded internally
by the Accelerator urinae. externally by the Erector penis, the base corresponding
to the Transversus perinei. The floor of this space is formed by the triangular
ligament of the urethra (deep perineal fascia), and, running from behind forwards
in it, are the superficial perineal vessels and nerves, the transversus perinei artery
coursing along the posterior boundary of the space, resting upon the Transversus
perinei muscle.
180
SURGICAL ANATOMY OF THE PERINEUM.
In the lateral operation of lithotomy, the knife is carried obliquely across the
back part of this space, downwards and outwards, into the ischio-rectal fossa,
dividing the Transversus perinei muscle and artery; the posterior fibres of the
Accelerator urinae, the superficial perineal vessels and nerve, and, more posteriorly,
the external hemorrhoidal vessels.
The superficial and transverse perineal arteries are described at p. 434 ■ and
the superficial perineal and inferior pudendal nerves, at pp. 586, 588.
The Accelerator urinae and Erector penis muscles should now be removed, when the deep
perineal fascia will be exposed, stretching across the front part of the outlet of the pelvis. The
urethra is seen perforating its centre, just behind the bulb ; and on either side is the crus penis,
connecting the corpus cavernosum with the ramus of the ischium and pubes.
Fig. 392. — Deep Perineal Fascia. On the left side, the anterior layer
has been removed.
Anterior layer ef
Dffp Perineal. Fascia Ttmcvtdi
Shewing
COMPRESSOR URETHRA
Internal Pudic Arty.
Arty ef tie Ba,lt
Conqu'r* Gland
The muscles of the perineum in the female are the
Sphincter vagina?.
Erector clitoridis.
Transversus perinei.
Compressor urethra?.
Sphincter ani.
Levator ani.
Coccygeus.
The Sphincter Vaginse surrounds the orifice of the vagina, and is analogous to
the Accelerator urinae in the male. It is attached, posteriorly, to the central
tendon of the perineum, where it blends with the Sphincter ani. Its fibres pass
forwards on each side of the vagina, to be inserted into the corpora cavernosa and
body of the clitoris.
The Erector Clitoridis resembles the Erector penis in the male, but is smaller
than it.
The Transversus Perinei is inserted into the side of the Sphincter vaginas, and
DEEP PERINEAL FASCIA. 181
the Levator ani into the side of the vagina. The other muscles are precisely
similar to those in the male.
The Deep Perineal Fascia (triangular ligament) is a dense membranous lamina,
which closes the front part of the outlet of the pelvis. It is triangular in shape,
about an inch and a half in depth, attached above, by its apex, to the under
surface of the symphysis pubis and sub-pubic ligament ; and, on each side, to the
rami of the ischia and pubes, beneath the crura penis. Its inferior margin or
base is directed towards the rectum, and connected to the central tendinous point
of the perineum. It is continuous with the deep layer of the superficial fascia,
in front of the Transversus perinei muscle, and with a thin fascia, which covers
the outer surface of the Levator ani muscle.
The deep perineal fascia is perforated by the urethra, about an inch below the
symphysis pubis. The aperture is circular in form, and about three or four lines
in diameter. Above this is the aperture for the dorsal vein of the penis ; and
outside the latter, the puclic nerve and artery pierce it.
The deep perineal fascia consists of two layers, anterior and posterior : these
are separated above, but united below.
The anterior layer is continued forwards, around the anterior part of the mem-
branous portion of the urethra, becoming lost upon the bulb.
The posterior layer is derived from the pelvic fascia : it is continued backwards
around the posterior part of the membranous portion of the urethra, and the
outer surface of the prostate gland.
If the anterior layer of this fascia is detached on either side, the following
parts are seen between it and the posterior layer : the sub-pubic ligament above,
close to the pubes ; the dorsal vein of the penis ; the membranous portion of the
urethra, and the muscles of the urethra ; Cowper's glands, and their ducts ; the
pudic vessels and nerve; the artery and nerve of the bulb, and a plexus of
veins.
The Compressor Urethrse (constrictor urethral) surrounds the whole length of
the membranous portion of the urethra, and is contained between the two layers
of the deep perineal fascia. It arises by aponeurotic fibres, from the upper part
of the ramus of the pubes on each side, to the extent of half or three quarters of
an inch ; each segment of the muscle passes inwards, and divides into two
fasciculi, which surround the urethra from the prostate gland behind, to the
bulbous portion of the urethra in front ; and unite, at the upper and lower sur-^
faces of this tube, with the muscle of the opposite side, by means of a tendinous
raphe.
Circular muscular fibres surround the membranous portion of the urethra, from
the bulb in front to the prostate gland behind : they are placed immediately beneath
the transverse fibres already described, and are continuous with the circular fibres
of the bladder. These fibres are involuntary.
Cowpers Glands are situated immediately below the membranous portion of the
urethra, close behind the bulb, and below the artery of the bulb (p. 736).
The Pudic vessels and Nerves are placed along the inner margin of the pubic arch
The Artery of the Bulb passes transversely inwards from the internal pudic along
the base of the triangular ligament, between the two layers of fascia, accompanied
by a branch of the pudic nerve (p. 434).
If the posterior layer of the deep perineal fascia is removed, and the crus
penis of one side detached from the bone, the under or perineal surface of the
Levator ani is brought fully into view. This muscle, with the triangular ligament
in front and the Coccygeus and Pyriformis behind, closes in the outlet of the
pelvis.
The Levator ani is a broad thin muscle, situated on each side of the pelvis. It
is attached to the inner surface of the 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
T82 SURGICAL ANATOMY OF THE PERINEUM.
pass through it. It arises, in front, from the posterior surface of the body and
ramus of the pubes, on the outer side of the symphysis ; posteriorly, from the
inner surface of the spine of the ischium ; and, between these two points, from
the angle of division between the obturator and recto- vesical layers of the pelvic
fascia at their under part : the fibres pass downwards to the middle line of the
floor of the pelvis, and are inserted, the most posterior fibres into the sides of the
apex of the coccyx ; those placed more anteriorly unite with the muscle of the
opposite side, in a median fibrous raphe, which extends between the coccyx and
the margin of the anus. The middle fibres, which form the larger portion of the
muscle, are inserted into the side of the rectum, blending with the fibres of the
Sphincter muscles : lastly, the anterior fibres, the longest, descend upon the side
of the prostate gland to unite beneath it with the muscle of the opposite side,
blending with the fibres of the External sphincter and Transversus perinei
muscles, at the tendinous centre of the perineum.
The anterior portion is occasionally separated from the rest of the muscle by
cellular tissue. From this circumstance, as well as from its peculiar relation with
the prostate gland, descending by its side and surrounding it as in a sling, it has
been described by Santorini and others as a distinct muscle, under the name of
the Levator prostatas. In the female, the anterior fibres of the Levator ani descend
upon the sides of the vagina.
Relations. By its upper 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 ; is
covered by a quantity of fat, and by a thin layer of fascia continued fron* the
obturator fascia. Its posterior border is continuous with the Coccygeus muscle.
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.
Actions. This muscle supports the lower end of the rectum and vagina, and
also the bladder during the efforts of expulsion.
The Coccygeus is 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 and lesser sacro-sciatic ligament, and is inserted, by its base,
into the margin of the coccyx and into the side of the lower piece of the sacrum.
This muscle is continuous with the posterior border of the Levator ani, and closes
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. By its posterior border, with the
Pyriformis.
Action. The Coccygei muscles raise and support the coccyx after it has been
pressed backwards during defecation or parturition.
Position of the Viscera at the Outlet of the Pelvis. Divide the central tendinous point of the
perineum, and separate the rectum from its connections by dividing the fibres of the Levator ani,
which descend upon the sides of the prostate gland, turn it backwards towards the coccyx, when
the under surface of the prostate gland, the neck and base of the bladder, the vesicuhe seminales,
and vasa deferentia will be exposed.
The Prostate Gland is placed immediately in front of the neck of the bladder,
around the prostatic portion of the urethra, its base being turned backwards, and
its under surface towards the rectum. It is retained in its position by the Levator
prostatas and by the pubo-prostatic ligaments, and is invested by a dense fibrous
covering, continued from the posterior layer of the deep perineal fascia, The
longest diameters of this gland are in the antero-posterior direction, and trans-
versely at its base ; and hence the greatest extent of incision that can be made
in it, without dividing its substance completely across, is obliquely outwards and
backwards. This is the direction in which the incision is made through it in
the operation of lithotomy, the extent of which should seldom exceed an inch in
length. The relations of the prostate to the rectum should be noticed : by means
POSITION OF VISCERA AT OUTLET OF PELVIS. 783
of the finger introduced into the gut, the surgeon readily detects enlargement or
other disease of this organ, and he is enabled by the same means, to direct the
point of a catheter when its introduction is attended with much difficulty, either
from injury or disease of the membranous or prostatic portions of the urethra.
Behind the prostate is the posterior surface of the neck and base of the bladder ;
a small triangular portion of this organ is seen, bounded, in front, by the prostate
gland ; behind, by the recto-vesical fold of the peritoneum ; on either side, by the
vesiculae seminales and vasa deferentia ; and 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 projecting into the rectum, between three and
four inches from the margin of the anus, and may be easily perforated during life
without injury to any important parts ; this portion of the bladder is, consequently,
Fig. 393. — A View of the Position of the Viscera at the Outlet of the Pelvis.
Artery of Corpus Caverntitum
iiorsa I Artery of Tenia
Artery if .Bnft,
Tntertnl Pudie Artery
Coirper'a IZanJ-^
frequently selected for the performance of the operation of tapping the bladder.
If the finger is introduced into the bowel, the surgeon may learn the position, as
well as the size and weight, of a calculus in the bladder ; and in the operation
for its removal, if, as is not unfrequently the case, it should be lodged behind an
enlarged prostate, it may be easily displaced from its position by pressing upwards
the base of the bladder from the rectum.
Parts concerned in the Ojieration of Lithotomy. The triangular ligament must be
replaced, the rectum drawn forwards so as to occupy its normal position, and the
student should then consider the position of the various parts in reference to the
lateral operation of lithotomy. This operation is usually performed on the left
side of the perineum, as it is most convenient for the right hand of the operator.
A staff having been introduced into the bladder, the first incision is commenced
about an inch and a half in front of the anus, a little on the left side of the raphe,
and carried obliquely backwards and outwards to midway between the anus and
tuberosity of the ischium. This incision divides the integument and superficial
m
SURGICAL ANATOMY OP THE PERINEUM.
fascia, the external hemorrhoidal vessels and nerves, and the superficial and trans-
verse perineal vessels ; if the forefinger of the left hand is thrust upwards and
forwards into the wound, pressing at the same time the rectum inwards and back-
wards, the staff may be felt in the membranous portion of the urethra. The finder
is fixed upon the staff, and the structures covering it are divided with the point
of the knife, which must be directed along the groove towards the bladder, the edge
of the knife being carried outwards and backwards, 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 staff having been
withdrawn, and the position of the stone determined upon, the forceps are intro-
duced over the finger into the bladder. If the stone is very large, the opposite
side of the prostate should be notched before the forceps is introduced ; the finger
is now withdrawn, the blades of the forceps opened, and made to grasp the stone,
which must be extracted by slow and cautious undulating movements.
Parts divided in the operation. The various structures divided in this operation
are as follows ; the integument, superficial fascia, external hemorrhoidal vessels
and nerve, the posterior fibres of the Accelerator urinte, the Trans versus perinei
muscle and artery (and, probably, the superficial perineal vessels and nerves), the
deep perineal fascia, the anterior fibres of the Levator ani, part of the Compressor
urethras, the membranous and prostatic portions of the urethra, and part of the
prostate gland.
Fig. 394. — A Transverse Section of the Pelvis ; showing the Pelvic Fascia.
AnteriorCruralJVcn<e
Femoral Vessels.
OhturafoT- Fascia.
Internal Pudic VisseU &. A>
*** <!fl
Parts to be avoided in the operation. In making the necessary incisions in the
perineum for the extraction of a calculus, the following rules should be observed:
The primary incision should not be made too near the middle line, for fear of
wounding the bulb of the corpus spongiosum or rectum ; nor too far externally,
otherwise the 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 backwards, the entire breadth of the
PELVIC FASCIA.
185
prostate and neck of the bladder may be cut through, which allows of infiltration
of urine behind the pelvic fascia into the loose cellular 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 consequence. If, on the contrary, the prostate is divided in front of
the base of the gland, the urine makes its way externally, and there is no danger
of any 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 the incision
made through the prostate and neck of the bladder be too small, great difficulty
may be experienced in introducing it afterwards ; 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 up into the abdomen, out of the
reach of the operator. Such a proceeding has not unfrequently occurred, pro-
ducing the most embarrassing results, and total failure of the operation.
Fig. 395. — Side View'of the Pelvic Viscera of the Male Subject, showing the Pelvic
and Perineal Fasciae.
It is necessary to bear in mind that the arteries in the perineum occasionally
take an abnormal course. Thus, the artery of the bulb, when it arises, as some-
times happens, from the pudic, opposite the tuber ischii, is liable to be wounded
in the operation for lithotomy, in its passage forwards to the bulb. The accessory
pudic may be divided near the posterior border of the prostate gland, if this is
completely cut across; and the prostatic veins, especially in people advanced in
life, are of large size, and give rise when divided to troublesome hemorrhage.
Pelvic Fascia.
The Pelvic Fascia is a thin membrane which lines the whole of the cavity 01
the pelvis, and is continuous with the transversalis and iliac fasciae. It is attached
50
786 PELYIC FASCIA.
to the brim of the pelvis for a short distance at the side of this cavity, and to the
inner surface of the bone round the attachment of the Obturator internus. At
the posterior border of this muscle, it is continued backwards as a very thin
membrane in front of the Pyriformis muscle and sacral nerves, behind the branches
of the internal iliac artery and vein which perforate it, to the front of the sacrum.
In front, it follows the attachment of the Obturator internus to the bone, arches
beneath the obturator vessels, completing the orifice of the obturator canal, and
at the front of the pelvis is attached to the lower part of the symphysis pubis ;
being continuous below the pubes with the fascia of the opposite side so as to
close the front part of the outlet of the pelvis, blending with the posterior layer
of the triangular ligament. At the level of a line extending from the lower
part of the symphysis pubis to the spine of the ischium, is a thickened whitish
band ; this marks the attachment of the Levator ani muscle to the pelvic fascia,
and corresponds to its point of division into two layers, the obturator and recto-
vesical.
The obturator fascia descends and covers the Obturator internus muscle. It is
a direct continuation of the pelvic fascia below the white line above mentioned,
and is attached to the pubic arch and to the margin of the great sacro-sciatic
ligament. This fascia forms a canal for the pudic vessels and nerve in their
passage forwards to the perineum, and is continuous with a thin membrane which
covers the perineal aspect of the Levator ani muscle, called the isckio-rectal or anal
fascia.
The recto-vesical fascia (visceral layer of the pelvic fascia) descends into the
pelvis upon the upper surface of the Levator ani muscle, and invests the prostate,
bladder, and rectum. From the inner surface of the symphysis pubis a short
rounded band is continued to the upper surface of the prostate and neck of the
bladder, forming the pubo-prostatic or anterior true ligaments of the bladder. At
the side, this fascia is connected to the side of the prostate, inclosing this gland
and the vesical prostatic plexus, and is continued upwards on the surface of the
bladder, forming the lateral true ligaments of the organ. Another prolongation
invests the vesiculas seminales, and passes across between the bladder and rectum,
being continuous with the same fascia of the opposite side. Another thin pro-
longation is reflected round 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 descending upon and being intimately adherent to the upper surface
of this muscle, while the under surface 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.
INDEX.1
Abdomen, 658
apertures found in, 659
boundaries of, 658
lymphatics of, 490
muscles of, 281
regions of, 659
viscera of, 659
Abdominal aorta. See Aorta,
abdominal.
muscles, 281
ring, external. 282, 760
internal, 763
viscera, position of, 659
Absorbent glands, 482
Absorbents, 481
Acervulus cerebri, 528
Acetabulum, 154
Air-cells, 720
Air-tubes, 711
Alae of nose, 580
of vomer, 92
Alimentary canal, 643
subdivisions of, 643.
See also Stomach, Intes-
tines, &c.
Allantois, 721
Alveoli, formation of, 651
of lower jaw, 93
of stomach, 666
of upper jaw, 85
Amphiarthrosis, 185
Ampullae of semicircular ca-
nals, 638
of tubuli lactiferi, 756
Amygdalae, 653
of cerebellum, 531, 532
Anastomosis of arteries, 358
Anatomy, descriptive, 33
surgical, 33. See also Surgi-
cal anatomy.
Angle of jaw, 95
nasal, 81
of pubes, 153
of rib, 117
sacro-vertebral, 50
Angular movement, 187
Animal constituent of bone, 33
Ankle-joint, 228
arteries of, 229
bones of, 228
ligaments of, 228
relations of tendons and ves-
sels, in front of, 229
behind, 229
Annulus ovalis, 693
Antihelix, 629
fossa of, 62 9
Antitragus, 629
Antrum of Highmore, 84
Anus, 775
muscles of, 776
Aorta, 361
divisions of, 361
sinuses of, 362
abdominal, 418
aneurism of, 420
branches of, 420
surgical anatomy of, 420
arch of, 361
aneurism of, 364
ascending part of, 362
branches of, 365
descending part of, 364
peculiarities of, 364
of branches of, 365
of conformation of, 364
of direction of, 364
surgical anatomy of, 364
transverse portion of, 363
descending, 416
thoracic, 417
aneurism of, 417
branches of, 417
surgical anatomy of, 417
Aortic opening. *Sfee Opening,
aortic,
valves. See Valves.
Apertura scalae vestibuli coch-
lea, 638
Aperture of iter chordae ante-
rius, 632
posterius, 632
of larynx, 707
of posterior nares, 109
See also Apertura and Open-
ings.
Aponeurosis, 237
of deltoid, 299
of external oblique, in ingui-
nal region, 759
infraspinous, 300
of insertion, 238
of investment, 238
of occipito-frontalis, 241
of soft palate, 653
pharyngeal, 656
subscapular, 299
supra-spinous, 300
Aponeurosis —
vertebral, 274
Apophysis, 35
Apparatus, lachrymal, 627
ligamentosus colli, 195
Appendages of eye, 625
of skin, 605
of uterus, 752
Appendices epiploicae, 603, 673
Appendix of left auricle, 695
of right auricle, 692
vermiformis, 671
Aqua labyrinthi, 640
Aquaeduetus cochleae, 70, 638
Fallopii, 633
Sylvii, 528
vestibuli, 70, 638
Aqueous chamber, epithelial
lining of, 623
humor, 622
secreting membrane of, 623
Arachnoid membrane of brain,
508
parietal layer of, 508
structure of, 508
visceral layer of, 509
of cord, 501
cavity of, 501
Arbor vitae of cerebellum, 533
uterinus, 750
Arch of aorta. See Aorta, arch
of.
of colon, 672
crural, 760
femoral, 760
deep, 771
nasal, 458
palmar, deep, 411
superficial, 414
plantar, 452
of pubes, 157
supraorbital, 64
of vertebra, 40
zygomatic, 105
Arciform fibres of medulla ob-
longata, 511
Areola of breast, 756
Arm, arteries of, 405
bones of, 129
fascia of, 302
muscles of back of, 304
front of, 302
nerves of, 569
veins of, 467
1 Each Artery, Nerve, Muscle, Ac, is placed in the Index under the head of Artery, Nerve, Muscle, Ac.
Carotid artery, for example, being found under Artery, carotid; Median nerve, under Nerve, median ; Ac.
787
788
INDEX.
Arnold's ganglion, 554
nerve, 559
canal for, 71
Arteria or Arteriae. See Ar-
tery.
A-rteriae receptaculi, 387
Artery or Arteries, 358
anastomoses of, 358
capillary, 360
coats of, 359
areolar, 359
contractile, 359
elastic, 359
external, 359
fenestrated, 359
internal, 359
middle, 359
distribution of, 358
epithelial lining of, 360
mode of division of, 358
of origin of branches of, 358
nerves of, 360
physical properties of, 360
sheath of, 360
structure of, 361
subdivision of, 358
surgical anatomy of, 361
tortuosity of, 359
vessels of, 360
abdominal, of lumbar, 428
accessory pudic, 433
acromial thoracic, 404
alar thoracic, 405
alveolar, 381
anastomotica magna of bra-
chial, 409
of femoral, 443
angular, 376
anterior auricular, 379
carpal, 412, 416
cerebellar, 397
cerebral, 390
choroid, 391
ciliary, 390, 624
circumflex, 405
communicating, 390
intercostal, 400, 418
interosseous, 416
meningeal, 387
peroneal, 452
spinal, 396
temporal, 375
ulnar recurrent, 415
aorta. See Aorta,
articular, of knee, inferior
external, 446
internal, 446
superior external, 446
internal, 445
of sciatic, 436
ascending cervical, 398
pharyngeal, 377
auditory, 397, 642
auricular, anterior, 379
posterior, 377
axillary, 402
branches of, 404
peculiarities of, 404
surgical anatomy of, 404
azygos articular of knee, 446
Artery or Arteries —
basilar, 397
brachial, 405
branches of, 408
peculiarities of, 407
surgical anatomy of, 408
bronchial, 418, 720
buccal, 381
of bulb of urethra, 434, 781
calcanean, internal, 452
carotid, 367
common, 367
left, relations of, 368
peculiarities of. 370
surgical anatomy of, 370
external, 371
surgical anatomy of, 371
internal, 385
cavernous portion, 386
cerebral portion, 386
cervical portion, 386
petrous portion, 386
surgical anatomy of, 386
carpal, anterior of radial, 412
of ulnar, 416
posterior of radial, 412
<»f ulnar, 416
of cavernous body, 434, 738
centralis modioli, 639
retina?, 390, 622
cerebellar, anterior, 397
inferior, 397
superior, 397
cerebral, anterior, 390
middle, 390
posterior, 397
cervical, ascending, 398
superficial, 398
princeps, 377
profunda, 400
choroid, anterior, 391
posterior, 397
ciliary, 390
anterior, 390, 624
long, 390, 624
short, 390, 624
circle of Willis, 397
circumflex of arm, 405
anterior, 405
posterior, 405
iliac, 438
superficial, 441
of thigh, 442
ascending branches of,
442
descending branches of,
442
external, 442
internal, 442
transverse branches of,
442
cochlear, 642
coccygeal, 435
cceliac axis, 421
colica dextra, 425
media, 425
sinistra, 425
comes nervi ischiadici, 435
phrenici. 399
communicating, anterior, of
brain, 390
Artery or Arteries —
posterior of brain, 390
communicating branch of
dorsalis pedis, 449
of ulnar, 416
coronary, of heart, 365
inferior, 375
left, 366
peculiarities of, 366
right, 365
superior, 376
of upper lip, 376
of lower lip, 375
of corpus cavernosum, 434
cremasteric, 438
crico-thyroid, 373
cutaneous, 445
cystic, 423
deep branch of ulnar, 416
cervical, 400
palmar arch, 411
temporal, 381
deferent, 432
dental, inferior, 381
superior, 381
descending palatine, 382
digital, of plantar, 453
of ulnar, 416
dorsal, of lumbar, 428
of penis, 434 -
of scapula, 405. See also
Artery, dorsalis.
dorsalis hallucis, 449
indicis, 412
linguae, 373
pedis, 448
branches of, 449
peculiarities of, 449
surgical anatomy of, 449
penis, 434
pollicis, 412
scapulae, 405
epigastric, 437
peculiarities of, 438
relation of, to external
ring, 771
to internal ring, 764
superior, 400
superficial, 411
ethmoidal, 388
external articular of knee,
445
carotid, 371
circumflex, 442
hemorrhoidal, 434
iliac, 436
malleolar, 448
obturator, 433
plantar, 452
pudic, 442
facial, 374
peculiarities of, 376
surgical anatomy of, 376
transverse, 378
femoral, 438
branches of, 441
peculiarities of, 440
surgical anatomy of, 440
deep, 442
frontal, 389
gastric, 421
INDEX.
789
Artery or Arteries —
of splenic, 423
gastro-duodenalis, 422
epiploica dextra, 422
gastro epiploica sinistra, 423
gluteal, 436
deep, 436
inferior, 435
superficial, 436
helicine, 738
hemorrhoidal, external, 434
inferior, 434
middle, 432
superior, 425
hepatic, 421, 678
hyoid branch of lingual. 373
of superior thyroid, 372
hypogastric, in foetus, 699, 701
how obliterated, 702
ileo-colic, 425
iliac, 428
circumflex, 438
common, 428
left, 428
right, 428
peculiarities of, 429
surgical anatomy of, 429
external, 436
surgical anatomy of, 437
internal 430
at birth, 431
peculiarities of, in foetus,
430
surgical anatomy of, 431
of ilio-lumbar, 436
inferior cerebellar, 397
coronary, 375
dental, 381
gluteal, 435
hemorrhoidal, 434
labial, 375
laryngeal, 373
meningeal, 377
mesenteric, 425
palatine, 375
perforating, 443
profunda, 409
p'idic, 442
pyloric, 422
thyroid, 398
vesical, 432
infra-orbital, 381
innominate, 366
peculiarities of, 366
surgical anatomy of, 367
intercostal, 400, 418
anterior, 400, 418
dorsal, 418
superior, 400, 418
internal auditory, 642
calcanean, 452
carotid, 385
circumflex of thigh, 442
iliac, 430
malleolar, 448
mammary, 399
maxillary, 379
obturator, 433
plantar, 452
pudic, 433
interosseous of ulnar, 415
Artery or Arteries —
dorsal of foot, 452
of hand, 415
anterior, 416
posterior, 416
of radial, 412
intestini tenuis, 424
labial, 375
inferior, 375
lachrymal, 388
laryngeal, 398
inferior, 373
superior, 373
lateral sacral, 436
spinal, 396
lateralis nasi, 376
lingual, 373
surgical anatomy of, 374
long ciliary, 370, 624
thoracic, 405
lumbar, 427
ilio-lumbar of the, 436
malleolar, 448
external, 448
internal, 448
mammary, internal, 399
masseteric, 381
maxillary, internal, 379
median, 397, 416
of forearm, 416
of spinal cord, 397
mediastinal, 400
posterior, 418
meningeal, from ascending
pharyngeal, 378
anterior, from carotid, 387
inferior, from occipital. 377
middle, from internal max-
illary, 379
posterior, from vertebral,
396
small, from internal max-
illary, 380
mesenteric, inferior, 425
superior, 423
metacarpal, 412
metatarsea, 449
metatarsal, 449
middle cerebral, 390
sacral, 428
musculo-phrenic, 400
mylo-hyoid, 381
nasal, 382
of ophthalmic, 389
of septum, 375
nutrient of femur, 443
fibula, 452
humerus, 409
radius, 416
tibia, 452
ulna, 416
obturator, 432
external, 433
internal, 433
peculiarities of, 433
relations of, in hernia, 772
occipital, 376
oesophageal, 398, 418
ophthalmic, 387
orbital, 380
ovarian, 427
Artery or Arteries —
palatine, ascending, 375
d3scending, 382
inferior, 375
of pharyngeal, 378
posterior, 382
palmar arch, deep, 411
superficial, 414
interosseae, 413
palpebral, 388
pancreatic, 423
pancreatica magnae, 423
parvae, 423
pancreatico-duodenalis, 423
inferior, 424
perforating, 313, 400. See
Perforating arteries,
pericardiac, 400, 417
perineal, superficial, 434
transverse, 434
peroneal, 451
anterior, 452
pharyngea ascendens, 377
phrenic, 427
superior, 399
plantar, 452
external, 452
internal, 452
popliteal, 444
branches of, 445
peculiarities of, 445
surgical anatomy of, 445
posterior auricular, 377
carpal, 412, 416
cerebral, 397
choroid, 397
circumflex of arm, 405
communicating, 390
interosseous, 416
meningeal, 396
palatine, 382
recurrent interosseous, 41 G
spinal, 397
scapular, 399
temporal, 378
ulnar recurrent, 415
princeps cervicis, 377
pollicis, 413
profunda of arm. inferior, 409
superior. 409
cervicis, 400
femoris, 442
pterygoid, 381
pterygopalatine, 382
pubic, 438
pudic, accessory, 433
external, 442
deep, 442
inferior, 442
superficial, 442
superior, 442
internal, 433
peculiarities of, 433
in female, 435
pulmonary, 453, 694, 720
pyloric, 422
inferior, 422
of hepatic, 422
radial, 410
branches of, 412
peculiarities of, 411
790
INDEX.
Artery or Arteries —
relations of, in forearm, 411
in hand, 411
surgical anatomy of, 411
radialis indicis, 413
ranine, 373
recurrent interosseous, poste-
rior, 416
radial, 412
tibial, 448
ulnar, anterior, 415
posterior, 415
renal, 426, 726
sacra media, 428
sacral, lateral, 436
middle, 428
scapular, posterior, 399
sciatic, 435
short ciliary, 390, 624
sigmoid, 425
spermatic, 427, 740
spheno-palatine, 382
spinal, anterior, 396
from the intercostal, 418
in the loins, 436
in the neck, 396
in the thorax, 418
lateral, 396
from the lumbar, 428
median, 397
posterior, 397
from the vertebral, 396
splenic, 423, 688
sterno-mastoid, 372
stylo-mastoid, 377
subclavian, 391
branches of, 395
first part of left, 392
left, 392
peculiarities of, 393
right, 392
second portion of, 392
surgical anatomy of, 393
third portion of, 393
sublingual, 373
submaxillary, 375
submental, 375
subscapular, 405
superficial cervical, 398
circumflex iliac, 441
epigastric, 441
palmar arch, 414
perineal, 434
superficialis volse, 412
superior cerebellar, 397
coronary, 376
dental, 381
epigastric, 400
hemorrhoidal, 425
intercostal, 400, 418
laryngeal, 373
mesenteric, 423
perforating, 443
phrenic, 399
profunda, 409
pudic, 442
thoracic, 404
thyroid, 372
vesical, 432
supra-orbital, 388
-renal, 426
Artery or Arteries — ■
supra-scapular, 398
sural, 445
tarsal, 449
tarsea, 449
temporal, 378
anterior, 378
deep, 381
middle, 378
posterior, 378
surgical anatomy of, 379
thoracic, acromial, 404
alar, 405
aorta, 417
long, 405
superior, 404
thyroid, inferior, 398
superior, 372
surgical anatomy of, 373
axis, 398
tibial, anterior, 446
branches of, 448
peculiarities of, 447
surgical anatomy of, 447
posterior, 450
branches of, 451
peculiarities of, 450
surgical anatomy of, 450
recurrent, 448
tonsillar, 375
transverse of basilar, 397
facial, 378
transversalis colli, 398
tympanic, from internal caro-
tid, 387
from internal maxillary, 37 9
ulnar, 413
branches of, 415
peculiarities of, 414
relations of, in forearm,
413
in hand, 414
in -wrist, 414
surgical anatomy of, 414
recurrent, anterior, 415
posterior, 415
umbilical in £cetus, 699, 701
how obliterated, 702
uterine, 432
vaginal, 432
vasa aberrantia of arm, 407
brevia, 423
intestini tenuis, 424
vertebral, 396
vesical, inferior, 432
middle, 432
superior, 432
vestibular, 642
Vidian, 382
Arthrodia, 185
Articular cartilage, 181
lamella of bone, 181
Articulations, 181
acromioclavicular, 208
ankle, 228
astragalo-calcanoal, 230
-scaphoid, 232
atlo-axoid, 191
calcaneo-astragaloid, 230
-cuboid, 230
-scaphoid, 231
Articulations —
carpal, 217
carpo-metacarpal, 218
classification of, 186
coccygeal, 205
costo-clavicular, 208
-sternal, 200
-transverse, 199
-vertebral, 197
elbow, 211
femoro-tibial, 223
of foot, 229
hand, 217
hip, 221
immovable, 184
knee, 223
larynx, 705
lower extremity, 221
metacarpal, 209
metacarpophalangeal, 220
metatarsal, 233
metatarso-phalangeal, 233
mixed, 185
movable, 185
movements of, 187
occipito-atloid, 194
-axoid, 195
of pelvis, 204
with spine, 203
phalanges, 234
pubic, 205
radio-carpal, 216
-ulnar, inferior. 214
middle, 214
superior, 213
sacro-coccvgeal, 205
-iliac, 204
-sciatic, 204
-vertebral, 203
scapuloclavicular, 208
humeral, 210
shoulder, 210
of spine with cranium, 193
sterno-clavicular, 207
of sternum, 202
tarsal, 229
tarso-metatarsal, 233
temporo- maxillary, 195
tibio-fibular, inferior, 227
middle, 227
superior, 226
of the trunk, 188
of tympanic bones, 635
of upper extremity, 207
of vertebral column, 188
wrist, 216
Ary teno-epiglottidean folds,707
Astragalus, 173
Atlas, 42
development of, 49
Atrabiliary capsules, 729
Auditory canal. See Canal,
auditory,
meatus, external, 69
internal, 70
Auricle of ear, 628
cartilage of, 629
ligaments of, 629
structure of, 62 'J
of heart, 691, 696
appendix of, 692, 695
INDEX.
191
Auricle of ear —
left, 695
openings in, 693, 696
right, 092
einus of, 692, 695
valves in, 693, 696
Auriculo-ventricular groove of
heart, 691
opening, left, 696, 697
right, 093. 094
Axes of the pelvis, 157
Axilla, 401
dissection of, 293
Axillary space, 401
surgical anatomy of, 401
Axis, 43
development of, 49
cerebro-spinal, 495
cceliac, 421
thyroid, 398
Axis-cylinder of nerve tubes,
496
Back, muscles of, first layer, 209
second layer, 272
third layer, 273
fourth layer, 276
fifth layer, 278
Bartholine, duct of, 655
gland of, 747
Base of brain, 517
of skull, external surface, 102
internal surface, 100
Bauhin, valve of, 671
Beale's researches on the liver,
680
Bend of elbow, 407
Berzelius's analysis of bone, 34
Bicuspid teeth, 046
Biliary ducts. See Ducts, bili-
ary.
Bladder, 729
arteries of, 732
base of, 730
body of, 730
cervix of, 730
false ligaments of, 731
female, relations of, 748
fundus of, 730
interior of, 731
ligaments of, 730
lymphatics of, 492, 732
neck of, 730
nerves of, 732
shape, position, and relations
of, 729
structure of, 731
summit of, 730
surgical anatomy of, 730
trigonum vesicae of, 732
true ligaments of, 730
uvula vesicae, 732
veins of, 732
Blood, circulation of, in adult,
691
in foetus, 700
Body of a tooth, 645
of a vertebra, 41
Bone, affected with rickets, ana-
lysis of, 34
animal constituent of, 33
Bone —
arteries of, 37
apophyses of, 35
articular eminences of, 35
canaliculi of, 37
cancellous tissue of, 33
chemical analysis of, 33
compact tissue of. 33
development of, 38
diploe of, 35
earthy constituent of, 33
eminences and depressions
of, 35
epiphyses of, 35
general properties of, 33
growth of, 40
Haversian canals of, 36
systems of, 36
spaces of, 37
inorganic constituent of, 33
lymphatics of, 38
marrow of, 38
medullary canal of, 38
membrane of, 38
microscopic structure of, 36
nerves of, 38
number of, 40
organic constituent of, 33
ossification of, 38
intra-cartilaginous, 39
intra-membranous, 39
period of, 39
ossific centres, number of,
39
mode of union of, 39
periosteum of, 38
spongy tissue of, 33
structure of, 33
of the extremities of, 35
of the shaft of, 35
surfaces of, 35
veins of, 37
vessels of, 37
ankle, 228
astragalus, 173
atlas, 42
axis, 43
calcaneum, 170
carpal, 140
clavicle, 121
coccyx, 54
cranial, 57
cuboid, 173
cuneiform of carpus, 141
of tarsus, 175
ear, 634
ethmoid, 77
facial, 57, 80
femur, 158
fibula, 168
finger, 147
flat, 34
foot, 170
forms of, 34
frontal, 63
hand, 140
humerus. 129
hyoid, 111
ilium, 149
incus, 034
Bone —
inferior maxillary, 92
turbinated, 91
innominate, 149
irregular, 35
ischium, 152
lachrymal, 86
lesser lachrymal, 86
lingual, 111
long, 35
magnum, 145
malar, 87
malleus. 634
maxillary, inferior, 92
superior, 81
metacarpal, 146
metatarsal, 177
mixed, 35
nasal, 81
navicular, of carpus, 1^1
of tarsus, 175
occipital, 57
orbicular, 634
palate, 88
parietal, 01
patella, 104
pelvic, 155
phalanges, of foot, 178
of hand, 147
pisiform, 143
pubic, 153
radius, 138
ribs, 116
sacrum, 50
scaphoid of carpus, 141
of tarsus, 175
scapula, 123
semilunar, 141
sesamoid, 179
short, 35
sphenoid, 72
sphenoidal spongy, 76
spongy, 91
stapes, 634
sternum, 112
superior maxillary, 81
supernumerary, 80
tarsal, 170
temporal, 67
tibia, 165
trapezium, 143
trapezoid, 143
triquetral, 80
turbinated, inferior, 91
middle, 78
superior, 78
tympanic, 634
ulna, 133
unciform, 145
ungual, 147
vertebra dentata, 43
prominens, 44
vertebrae, cervical, 41
coccygeal, 54
dorsal, 44
lumbar, 47
sacral, 50
vomer, 92
Wormian, 80
Bostock's analysis of a rickety
bone, 34
792
INDEX.
Bowman on structure of kidney,
725
Brachia of optic lobes, 529
Brain, 507. See also Cerebrum.
arachnoid of, 508
base of, 517
dura mater of, 507
interior of, 519
lateral ventricles of, 522
lobe of, anterior, 517
middle of, 517
posterior of, 517
membranes of, 507
pia mater of, 509
subdivision into parts, 507
under surface of, 517
upper surface of, 517
weight of, 507.
Breasts, 756
Brim of pelvis, 155
Bronchi, 712
mode of subdivision in lung,
719
septum of, 712
structure of, in lobules of
lung, 719
Brunner's glands, 669
Bubonocele, 765
Bulb, artery of, 434, 781
of corpus cavernosum, 434,
738
of corpus spongiosum, 434,
738
olfactory, 535
Bulbi vestibuli, 747
Bulbous portion of urethra, 733
Bulbs of the fornix, 519
Bursa? mucosae, 184
Bursal synovial membranes, 184
Cecum, 670
Calamus scriptorius, 512
Calcaneum, 170
Calyces of kidney, 726
Canal or Canals —
accessory palatine, 88
alimentary, 643
anterior dental, 83
palatine, 85, 102
for Arnold's nerve, 71
auditory, 631
cartilaginous portion of.
631
external, 69, 631
internal, 70, 642
osseous portion of, 631
carotid, 70
central of modiolus, 639
for chorda tympani, 68, 631
of cochlea, 638
crural, 771
dental, anterior, 83
inferior, 94
posterior, 82
ethmoidal, anterior, 66, 78
posterior, 66, 78
femoral, 771
Haversian, of bene, 36
incisive, 102
infraorbital, 83
inguinal, 762
Canal or Canals —
for Jacobson's nerve, 71
lachyrmal, 83, 628
malar, 88
nasal, 81
naso-palatine, 82
of Nuck, 745
palatine, accessory, 88
anterior, 90
posterior, 88
of Petit, 624
portal, 680
pterygoid, 75
pterygopalatine, 74
sacral, 53
spermatic, 762
of spinal cord, 506
spiral, of cochlea, 639
of modiolus, 639
semicircular, See Semicir-
cular canals.
for tensor tympani, 634
vertebral, 57
Vidian, 75
of Wirsung, 683
Canaliculi of bone, 37
of eyelids, 628
Canalis spiralis modioli, 640
Cancellous tissue of bone, 33
Canthi of eyelids, 625
Capillaries, 360
diameter of, 360
form of, 360
number of, 361
structure of, 361
pulmonary, 720
Capitula laryngis, 705
Capsule, atrabiliary, 728
of Glisson, 678
of the lens, 623
in foetus, 623
of Malpighian bodies of kid-
ney, 726
supra-renal, 727
Caput cornu posterius, 505
gallinaginis, 733
Carpus, 140
articulations of, 217
development of, 148
Cartilage or Cartilages —
articular, 181, 182
arytenoid, 704
of auricle, 629
of bronchi, 720
cells of, 181
circumferential, 183
connecting, 183
costal, 120
cricoid, 704
cuneiform, 705
of ear, 629
ensiform, 114
of epiglottis, 705
fibro-, 183. See Fibro-carti-
lage.
intcrarticular, 183
intercellular substance of, 182
interosseous, 183
of larynx, 703
structure of, 705
of the nose, 612
Cartilage or Cartilages —
of the pinna, 629
of Santorini, 705
palpebral, 625
permanent, 181
reticular, 182
semilunar of knee, 225
of septum of nose, 612
spongy, 182
stratiform, 183
structure of, 181
tarsal, 625
temporary, 38, 181
thyroid, 703
of trachea, 712
of Wrisberg, 705
xiphoid, 114
yellow, 182
Cartilagines minores of nose,
612
Cartilago triticea, 706
Caruncle, lachrymal, 626
Caruncula lacrymalis, 626
mammillaris, 536
Caruncula? myrtiformes, 747
Casserian ganglion, 546
Cauda equina, 502, 584
Cava, vena. iSee Vena cava.
Cavernous body, artery of, 434,
738
Cavities of reserve of the teeth,
651
Cavity, cotyloid. 153
digital of fifth ventricle, 523
of lateral ventricle, 523
glenoid, 127
of pelvis, 156
sigmoid, 135, 139
of radius, 139
of ulna, 135
Cells of bone, 37
ethmoidal, 78
hepatic, 679, 680
mastoid, 69
Cement of teeth, 649
formation of, 651 '
Centres of ossification, 39
Centrum ovale majus, 521
minus, 520
Cerebelli incisura anterior. 531
posterior, 531
Cerebellum, 530
corpus dentatum of, 533
ganglion of, 533
hemispheres of, 530
lamina? of, 531, 533
lobes of, 531
lobulus centralis, 530
median lobe of, 529
peduncles of, 529, 533, 534
structure of, 533
under surface of, 531
upper surface of, 530
valley of, 531
ventricle of, 533
weight of, 530
Cerebro-spinal axis, 495
fluid, 501, 509
nerves, 498
Cerebrum, 515
base of, 517
INDEX.
793
Cerebrum —
commissures of, 528
convolutions of, 515
cortical substance of, 515
crura of, 520
fibres of, 529
fissure of Sylvius, 518
longitudinal, 517
general arrangement of its
parts, 520
gray matter of, 515
hemispheres of, 515
interior of, 520
labia of, 521
lobes of, 517
peduncles of, 519
structure of, 529
sulci, 515, 516
tmperior ganglia of, 523, 527
nnder surface of, 517
upper surface of, 515
ventricles of, 522
Cervix cornu posterius, 505
uteri, 750
Chambers of the eye, 622
Cheek, muscles of, 248
Cheeks, 644
structure of, 644
Chemical analysis of bone, 33
of cerebro-spinal fluid, 509
of dentine or ivory, 648
of enamel, 648
of nervous substance, 495
of synovia, 184
of thymus gland, 723
of thyroid gland, 722
Chest, muscles of front of, 294
muscles of side of, 298
Chiasma or optic commissure,
537
Chorda tympani, 542, 637
Chordae tendineae of left ventri-
cle 697
of right, 694, 695
vocales, 707, 708
Willisii, 463
Choroid coat of eye, 617
structure of, 618
plexus of fourth ventricle,
532
of lateral ventricle, 523
of third ventricle, 526
Chyli receptaculum, 481
Cilia or evelashes, 626
Circle of Willis, 397
Circulation of blood in adults,
358, 691
in foetus, 699-702
pulmonic, 358
systemic, 358
Circulus tonsillaris, 557
Circumduction, 187
Cistern of Pecquet, 683
Clarke, Lockhart, researches on
the spinal cord, 505, 506
Clavicle, 121
articulations of, 123
attachments of muscles to,
123
development of, 123
fracture of, 320
Clavicle —
of acromial end of, 321
of sternal end of, 321
peculiarities of, 123
structure of, 123
Clitoris, 747
fraenum of, 747
lymphatics of, 491
muscles of, 747, 780
prepuce of, 747
structure of, 747
Coccyx, 54
articulations of, 55
attachment of muscles to, 55
cornua of, 55
development of, 55
Cochlea, 639
aqueduct of, 70, 640
arteries of, 642
central axis of, 639
cupola of, 639
denticulate lamina of, 640
hamular process of, 640
infundibulum of, 639
lamina spiralis of, 639
membranous zone of, 639
modiolus of, 639
nerves of, 642
osseous zone of, 640
scala tympani of, 640
vestibuli of, 640
scalae of, 640
spiral canal of, 639
veins of, 642
Collateral circulation after liga-
tion of brachial, 409
common carotid, 371
femoral, 441
iliac, common, 430
external, 437
internal, 431
subclavian, 395
Colles's fracture, 324
Colliculus bulbi urethras, 737
Colon, 672
ascending, 672
descending, 672
sigmoid flexure of, 672
transverse, 672
Columella cochleae, 639
Column, posterior vesicular of
spinal cord, 505
Columnae carneae of left ventri-
cle, 697
of right ventricle, 695
papillares, 695, 697
Columnar layer of retina, 621
Columns of abdominal ring, 760
of medulla oblongata, 511
of rectum, 674
of spinal cord, 504
of vagina, 749
Commissura brevis of cerebel-
lum, 531
simplex of cerebellum, 531
Commissure of flocculus, 531
optic, 519
Commissures of brain, anterior,
528
middle, 528
posterior, 528
Commissures of brain —
soft, 528
of spinal cord, gray, 504
white, 504
Compact tissue of bone, 33
Conarium, 528
Concha, 629
Condyles of bones. See Bones.
Congenital fissures in cranium,
80
Coni vasculosi, 741
Conjoined tendon of internr.l
oblique and transversals,
284, 761
Conjunctiva, 626
palpebral folds of, 627
Conjunctival epithelium, 616
Conus arteriosus, 694
Convolution of corpus callosum,
517
of longitudinal fissure, 517
supra-orbital, 517
Convolutions of cerebrum, cor-
tical substance of, 515
structure of, 515
white matter of, 515
Cord, spermatic. See Sperm-
atic cord,
spinal. See Spinal Cord.
Cordiform tendon, 291
Cords, vocal. See Yocal cords.
Corium of skin, 603
Cornea, 616
arteries and nerves of, 617
elastic laminae of, 616
proper substance of, 616
structure of, 616
Cornicula laryngis, 705
Cornu Ammonis, 524
Cornua of the coccyx, 55
of hyoid bone, 112
of sacrum, 51
of thyroid cartilage, 704
Corona glandis, 736
Corpora albicantia, 519
Arantii, 695, 697
cavernosa clitoridis, 747
penis, 737
crura of, 737
structure of, 737
geniculata, 529
lutca. See Corpus luteum.
olivaria, 511
pyramidalia, 511
quadrigemina, 529
restiformia,511
striata, 523
veins of, 463
Corpus Arantii, 695, 697
callosum, 517, 518, 521
convolution of, 517
genu of, 521
peduncles of, 518, 522
rostrum of, 521
ventricle of, 521
cavernosura. See Corpora
cavernosa,
colliculi bulbi, 737
dentatum of cerebellum, 533
of olivary body, 513
fimbriatum, 524, 525, 526
794
INDEX.
Corpus —
geniculaturn externum, 529
internum, 529
Highmorianum, 740
luteum, 754
structure of, 755
false, 755
true, 755
spongiosum, 737
arteries of, 738
structure of, 738
>See also Corpora.
Corpuscles, Malpighian, of kid-
ney, 726
of spleen, 68G
C ortical substance of brain, 495
of cerebral convolutions, 515
of kidney, 725
of supra-renal capsules, 728
of teeth, 649
Costal cartilages, 120
Coverings of hernia. See Her-
nia,
of testis. See Testis.
Cowper's glands, 736, 781
Cranial bones, 57
articulations of, 97. •
See also Bones, cranial.
Cranial nerves, 535
classification of, 535
nerves of special sense, 535
of common sensation,
545
of motion, 537
mixed, 560
first pair, 535
second, 536
third, 537
fourth, 538
fifth, 545
sixth, 539
seventh, soft portion, 537
hard portion, 540
eighth, glosso- pharyngeal,
555
spinal accessory, 560
vagus, 557
ninth, 544
Cranium, articulations of, 79
development of bones of, 57
See also Skull,
('rest, frontal, 65
of ilium, 150
nasal, 81
occipital, 58
internal, 60
of pubes, 153
of tibia, 166
turbinated, of palate, 88
of superior maxillary, 85
Cricoid cartilage, 704
Crista galli, 77
ilii, 150
pubis, 153
Crown of tooth, 645
Crura cerebelli, 533
cerebri, 519
of clitoris, 747
of corpora cavernosa, 737
of diaphragm, 290
of fornix, 526
Crural canal. See Canal, cru-
ral,
ring. See Ring, crural.
Crusta petrosa of teeth, 648
Crypts of Lieberkiihn, 669
Crystalline lens. See Lens,
crystalline.
Cuboid bone, 173
Cuneiform bone of foot, 175
of hand, 141
external, 176
internal, 175
middle, 176
Cupola of cochlea, 639
Curling on the development of
the testes, 745
Curvatures of the spine, 55
Cutaneous nerves. Sec Nerves,
cutaneous.
Cuticle, 604
Cutis vera, 603
Dartos, 739
Decussation of optic nerves,
537
of pyramids, 511
Deciduous teeth, 645
Dens sapientise, 647
Dentine, 648
chemical composition of, 648
formation of, 650
Depression of bones, 35
coronoid, 132
for Pacchionian bodies, 62
Derma or true skin, 603
Descent of testicle, 745
Development of atlas, 49
axis, 49
bone, 38
carpus, 148
clavicle, 122
coccyx, 54
cranium, 79
ethmoid, 78
femur, 163
fibula, 170
foot, 179
frontal bone, 66
hand, 148
hurnerus, 132
hyoid bone, 112
inferior turbinated bone, 91
lachrymal bone, 86
lower jaw, 95
lumbar vertebra?, 49
malar bone, 88
metacarpus, 148
metatarsus, 179
nasal bone, 81
occipital bone, 61
os innominatum, 154
palate bone, 90
parietal bone, 63
patella, 164
permanent teeth, 651
phalanges of foot, 179
of hand, 148
radius, 140
ribs, 118
sacrum, 54
scapula, 127
Development —
seventh cervical vertebra, 49
sphenoid, 76
sternum, 114
superior maxillary bone, 85
tarsus, 178
teeth, 649
temporal bone, 71
temporary teeth, 649
tibia, 168
ulna, 138
vertebra;, 48
vomer, 92
Wormian bones, 80
Diameters of pelvis, 156
Diaphragm, 289
aortic opening of, 291
lymphatics of, 494
serous membranes of, 291
Diaphysis, 39
Diarthrosis, 185
rotatorius, 186
Digestion, organs of, 643
Diploe, 35
veins of, 461
Direct inguinal hernia. See
Hernia.
Discharge of ovum, 754
Discus proligerus, 754
Dissection of muscles, regions,
hernia, &c. See Mus«l<?a,
Eegions, Hernia, &c.
Dorsum of penis, 736
of scapula, 118
Duct or Ducts —
aberrant of testis, 742
of Bartholine, 655
biliarv. 682
glands of, 682
structure of, 682
common choledoch, 688
of Cowper's gland, 7~6
cystic, 682
valve of, 682
ejaculatory, 744
galactophorous, 756
hepatic, 680. 6.^1
of kidney. 726
lactiferous, 756
of liver, 6v 0
lymphatic, right, 484
nasal, 628
of pancreas, 683
parotid, 654
seminal, 744
Steno's, 654
thoracic, 483
Whartonian, 655
Ductless glands. See Glands,
ductless.
Ductus arteriosus, 699, 701
how obliterated in foetus.
702
communis choledochus, 682
pancreaticus minor, 684
lliviniani. 655
venosus, 699, 701
how obliterated, 702
Duodenum, 667
vessels and nerves of. 668
Dura mater of brain, 507
INDEX.
795
Dura mater —
arteries of, 507
nerves of, 507
processes of, 508
structure of, 507
veins of, 507
of cord, 500
peculiarities of, 501
Ear, 628
arteries of, 631, 636, 642
auditory canal, 631
auricle of, 628
cochlea, 639
external, 628
helix of, 629
internal, 637
labyrinth, 637
membranous, 640
middle, 632
muscles of, 241, 630, 636
of auricle, 241, 630
of tympanum, 636
ossicula of, 634
pinna, 628
semicircular canals, 638
tympanum, 632. See also
Tympanum.
vestibule, 637
Earthy constituent of bone,
33
Ecker on supra-renal capsules,
728
Eighth pair of nerves, 555
Ejaculatory ducts, 744
structure of, 744
Elbow, bend of, 407
joint, 211
vessels and nerves of, 212,
213
Eminence of aquaxluctus Fal-
lopii, 633
of bones, 35
canine, 82
frontal, 64
ilio-pectineal, 153
jugular, 59
nasal, 67
parietal, 61
Eminentia articularis, 67
collateralis, 523, 525
Enamel of teeth, 649
chemical composition of, 649
formation of, 651
membrane, 651
organ, 651
rods, 649
Enarthrosis, 185
Endocardium, 697
Endolymph, 642
Ensiform appendix, 114
Epidermis, 604
development of, 664
growth of, 064
structure of, 664
Epididymis, 739
Epiglottic glands, 711
Epiglottis, 705
muscles of, 710
Epiphyses, 35
separation of, 40
Epithelium of skin, tongue, &c.
See Skin, Tongue, &c.
Erectile tissue, structure of, 738
of penis, 738
of vulva, 747
Eruption of the teeth, 651
Ethmoid bone, 77
articulations of, 78
cribriform plate of, 77
development of, 78
lateral masses of, 78
perpendicular plate of, 77
os planum of, 78
unciform process of, 78
Eustachian tube, 634
tympanic orifice of, 634
valve, 693
in foetal heart. 699
Eye, 614
appendages of, 625
arteries of, 624, 625
chambers of, 622
ciliary ligament, 620
muscle, 620
processes, 618
humors of, 622
aqueous, 622
crystalline lens, 623
vitreous, 623
membrana pupillaris, 620
membranes of, 615
choroid, 618
conjunctiva, 626
cornea, 616
hyaloid, 623
iris, 619
Jacob's, 621
retina, 620
sclerotic, 615
pupil of, 619
tunics of, 615
uvea of, 619
vessels of globe of, 624
Eyeball, 614
„ muscles of, 243
nerves of, 625
tunics of, 615
veins of, 625
Eyebrows, 625
Eyelashes, 626
Eyelids, 625
cartilages of, 625
Meibomian glands of, 625
muscles of, 242. 625
structure of, 625
tarsal ligament of, 626
Eye-teeth, 646
Face, arteries of, 374
bones of, 57, 80
lymphatics of, 484
muscles of. 242
nerves of, 542
veins of, 458
Facial bones, 57, 80
Falciform process of fascia lata,
769
Fallopian tubes, 752
fimbriated extremity of, 752
lymphatics of, 492
nerves of, 755
Fallopian tubes —
structure of, 752
vessels of, 755
Falx cerebelli, 508
cerebri, 508
Fangs of teeth, 645
Fascia or Fasciae, 235, 236
anal, 786
aponeurotic, 237
of arm, 302
cervical, deep, 254
superficial, 253
costo-coracoid, 296
cremasteric, 740, 762
cribriform, 768
deep, 237
dentata, 525
dorsal, of foot, 350
of face, 238
fibro-areolar, 237
of foot, 349
of forearm, 305
of hand, 316
of head, 238
iliac, 325
infundibuliform, 763
intercolumnar, 283, 760
intercostal, 288
intermuscular, of arm, 302
of foot, 349
of thigh, 328
ischio-rectal, 775, 786
lata, 328, 768
falciform process of, 769
iliac portion of, 768
pubic portion of, 769
of leg, 340
lumbar, 285
lumborum, 285
of mamma, 294
of neck, 253
obturator, 786
palmar, 316
pelvic, 785
obturator layer, 786
parietal layer, 786
visceral layer, 786
perineal, deep, 780
superficial, 777
plantar, 349
propria, 740
recto-vesical, 786
spermatic, 760
superficial, 237
of epicranial region, 240
of inguinal region, 758
of ischio-rectal region, 775
perineal, 777
of thigh, 327
' of thoracic region, 294, 298
of upper extremity, 294.
298
temporal, 250
of thigh, deep, 328
superficial, 327
of thorax, 293, 294
transversalis, 763
Fasciculi graciles. 511
teretes, 514, 532
Fasciculis unciformis, 518
Fauces, isthmus of, 653
796
INDEX.
Female organs of generation,
746
bulbi vestibuli, 747
carunculae myrtiformes, 747
clitoris, 747
fossa navicularis, 747
fraenulum pudendi, 747
glands of Bartholine, 747
hymen, 747
labia majora, 746
minora, 747
nympliae, 747
praeputium clitoridis, 747
uterus, 750
vagina, 749
vestibule, 747
Femoral hernia. See Hernia,
femoral.
Femur, 158
articulations of, 163
attachment of muscles to, 163
development of, 163
fracture of, above condyles,
355
below trochanters, 355
of neck of, 355
structure of, 162
Fenestra ovalis, 633, 639
rotunda, 633, 639
Ferrein, pyramids of, 726
tubes of, 726
Fibrae arciformes, 511, 513
transversa?, 532
Fibrin of muscle, 235
Fibro-cartilage, 183
acromio-clavicular, 209
circumferential, 183
connecting, 183
interarticular, 183. See In-
terarticular.
intercoccygean, 205
interosseous, 183
intervertebral, 189
of knee, 225
of lower jaw, 197
pubic, 206
radio-ulnar, 214
sacro-coccygeal, 205
semilunar, 225
sterno-clavicular, 208
stratiform, 183
triangular, 214
Fibrous nervous matter, 495
Fibula, 168
articulations of, 170
attachment of muscles to,
170
development of, 170
fracture of, with dislocation
of the tibia, 357
Fibrous rings of heart, 697
Fifth pair of nerves, 545
ventricle of brain, 525
Fimbriae of Fallopian tube, 752
Fissura palpebrarum, 625
Fissure, auricular, 71
of cerebellum, horizontal. 531
of cranial bones, congenital,
80
of ductus venosus, 677
for gall-bladder, 677
Fissure — ■
Glaserian, 68, 632
of helix, 629
of liver, 677
longitudinal, of cerebrum,
515, 517
of liver, 676
of lung, 718
maxillary, 83
of medulla oblongata, 511
palpebral, 625
portal, 677
posterior lateral, 503
median, 503
pterygo-maxillary, 106
spheno-maxillary, 106
sphenoidal, 75, 101
of spinal cord, anterior late-
ral, 503
median, 503
of Sylvius, 518
of tragus, 629
transverse, of cerebrum, 525
of liver, 677
umbilical, of liver, 677
for vena cava, 677
Floating ribs, 116
Flocculus, 532
Foetus, circulation in, 699, 700
Eustachian valve in, 693
foramen ovale in, 693
liver of, distribution of its
vessels, 699
ovaries in, 755
peculiarities of vascular sys-
tem in, 699
relics in heart of, 693
Folds, aryteno - epiglottidean,
705, 710
recto-uterine, 750
recto-vesical, 730
vesico-uterine, 750
Follicle of hair, 606
Follicles, dental, 650
gastric, 666
sebaceous, 607
Follicular stage of development
of teeth, 650
Fontanelles, 60, 62, 79
anterior, 62, 79
posterior, 60, 62, 79
Foot, arteries of, 448, 452
bones of, 170
development of, 179
dorsal region of, muscles of,
350
fascia of, 349
ligaments of, 228, 229, 230
nerves of, 589
plantar region of, muscles of,
350
vessels of, 448, 452, 473
veins of, 473
Foramen. See also Foramina,
caecum of frontal bone, 69,
100
of medulla oblongata, 511
of tongue, 609
carotid, 70
condyloid, 59
inferior dental, 98
Foramen —
incisive, 102
infra-orbital, 83
intervertebral, 57
jugular, 101
lacerum anterius, 101
medium, 101
posterius, 101
magnum, 58, 60
mastoid, 69
mental, 93
of Monro, 523, 526
obturator, 154
optic, 73, 100
ovale of heart, 699
of sphenoid, 74, 101
palatine, anterior, 85, 102
posterior, 88
parietal, 61
pterygoid, 75
pterygopalatine, 74
rotundum, 74, 101
sacro-sciatic, great, 152, 154,
205
small, 152, 154, 205
of Sbmmering, 621
spheno-palatine, 110
spinosum, 74, 101
sternal, 114
stylo-mastoid, 71
supra-orbital, 64
thyroid, 154
vertebral, 42
Vesalii, 74, 101
of Winslow, 661
Foramina of diaphragm, 291
external orbitar, 74
malar, 87
olfactory, 77
sacral, 51
Thebesii, 479, 693
Forearm, arteries of, 410
bones of, 133
fascia of, 305
lymphatics of, 488
muscles of, 305
nerves of, 569
veins of, 466
vessels of, 410, 466, 488
Foreskin. 736
Fornix, 524, 525
body of, 526
bulb of, 519
crura of, 526
Fossa of antihelix, 629
canine, 82
cerebral, 100
condyloid, 59
cystidis fellege, 677
digastric, 59
digital, 159
glenoid, 68
of helix, 629
iliac, 150
infra-spinous, 124
incisive, 82, 92
innominata, 629
ischio-rectal, 776
jugular, 104
lachrymal, 65
myrtiform, 82
INDEX.
797
rossa —
navicular of urethra, 733
of vulva, 747
occipital, inferior, 60
ovalis, 693
palatine, anterior, 85, 102
pituitary, 73
pterygoid of sphenoid, 75
of lower jaw, 95
scaphoid, 75
ecaphoidea, 629
spheno-maxillary, 106
of skull, anterior, 100
middle, 100
posterior, 101
sublingual, 93
submaxillary, 94
subscapular, 123
supra-spinous, 124
temporal, 105
trochanteric, 159
zygomatic, 106
Fossae, cranial, 100
nasal. See Nasal fossae.
Fourchette, 747
Fourth nerve, 538
ventricle, 532
Fovea centralis retinae, 621
hemispherica, 638
semi-elliptica, 638
Fracture of acromion process,
321
clavicle, 320
acromial end of, 321
centre of, 320
sternal end of, 321
Colles's, 323
coracoid process, 321
coronoid process of ulna, 322
femur above condyles, 355
belbw trochanters, 355
neck of, 355
fibula, with dislocation of ti-
bia, 357
humerus, 321, 322
anatomical neck, 321
shaft of, 322
surgical neck, 321
olecranon process, 322
patella, 356
Pott's, 357
radius, 323
lower end of, 323
neck of, 323
shaft of, 323
and ulna, 323
tibia, shaft of, 356
ulna, 323
shaft of, 323
Fraena of ileo-ccecal valve, 671
Fraenulum cerebri, 529
pudendi, 747
of Vieussens's valve, 529
Fraenum clitoridis, 747
labii inferioris, 643
superioris, 643
praeputii, 736
Frontal bone, 63
articulations of, 66
attachment of muscles to,
66
Frontal bone —
development of, 66
structure of, 66
Fundus of bladder, 731
of uterus, 750
Funiculi of nerve, 498
Funiculus, 498
Furrow, auriculo- ventricular,
691
interventricular, 691
Furrowed band of cerebellum,
531
Galactophorous ducts, 756
Gall-bladder, 681
duct of, 681
fissure for, 677
structure of, 681
valve of, 681
Ganglia, 497. See Ganglion.
cardiac, 596
cephalic, 551, 594
of fifth nerve, 551
lumbar, 600
lymphatic, 482
mesenteric, 599
renal, 598
sacral, 600
semilunar of abdomen, 598
solar, 598
of spinal nerves, 562
of sympathetic nerve, 592
branches from, 592
thoracic, 597
Ganglion, Arnold's, 554, 594
of Andersch, 555
carotid, 595
Casserian, 546
cervical, inferior, 595
middle, 594
superior, 594
ciliary, 551
on circumflex nerve, 569
diaphragmatic, 598
on facial nerve, 541
glossopharyngeal, 555
impar, 592, 600
inferior cervical, 595
intercarotid, 595
on interosseous nerve, pos-
terior, 576
jugular, 555, 557
lenticular, 551
lingual, 594
Meckel's, 552, 594
middle cervical, 595
ophthalmic, 551, 594
otic, 554, 594
petrous, 556
pharyngeal, 557, 594
pneumogastric, 557, 558
of portio dura, 541
of Ribes, 592
of root of vagus, 558
semilunar of fifth nerve, 546
of sympathetic. 598
spheno-palatine, 552. 594
submaxillary, 555, &94
superior cervical, 594
supra-renal, 598
temporal, 594
4
Ganglion —
thyroid, 595
of trunk of vagus, 557, 558
of Wrisberg, 597
Ganglion corpuscles, 497
Generative organs, female, 747.
See Female organs of gene-
ration,
male, 735. See Male organs.
Genu of corpus callosum, 521
Germinal spot of ovum, 754
vesicle of ovum, 754
Gimbernat's ligament, 281, 760,
770
Ginglymus, 186
Gladiolus, 114
Gland or Glands —
absorbent, 482
accessory of parotid, 654
aggregate, 669
agminate, 669
arytenoid, 711
of Bartholine, 747
of biliary ducts, 681
Brunner's, 669, 781
buccal, 644
ceruminous, 632
Cowper's, 736
duodenal, 669
ductless, 684, 721, 722, 727
spleen, 684
supra-renal, 727
thymus, 722
thyroid, 721
epiglottic, 711
gastric, 666
of Havers, 184
kidney, 724
labial, 643
lachrymal, 628
of larynx, 711
lingual, 610
of Littre, 733
liver, 675
lumbar, 435
lymphatic, 482
anterior tibiaf, 488
auricular, 484
axillary, 487
bronchial, 494
buccal, 484
cervical, 485
conglobate, 482
gluteal, 489
iliac, 490
inguinal, 488
intercostal, 493
internal mammary, 4C3
ischiatic, 489
of large intestine, 493
lumbar, 490
mediastinal, 493
mesenteric, 493
of neck, 485
oesophageal, 494
occipital, 484
parotid, 485
popliteal, 489
sacral, 490
of spleen, 493
of stomach, 492
798
INDEX.
Gland or Glands —
submaxillary, 484
thoracic, 493
zygomatic, 484
mammary, 756
Meibomian, 626
molar, 644
mucilaginous of Havers, 184
odoriferoe, 736
oesophageal, 658
of Pacchioni, 507
palatine, 652
pancreas, 683
parotid. See Parotid gland.
peptic, 666
Peyer's, 670
pharyngeal, 656
pineal, 528
pituitary, 519
prostate. See Prostate gland.
salivary, 653
sebaceous, 607
solitary, 669, 675
sublingual. See Sublingual
gland.
submaxillary. See Submax-
illary gland.
sudoriferous, 607
supra-renal, 727
sweat, 607
thymus, 722
thyroid. See Thyroid gland.
of tongue, 610
tracheal, 713
of Tyson, 736
uterine, 754
of vulva, 747
Glandulse odorifera;, 736
Pacchioni, 463, 507
solitariae, 669
Tysonii, 736
Glans clitoridis, 747
penis, 736
Gliding movement, 187
Glisson's capsule, 662, 678
Globus major of epididymis,
739
minor of epididymis, 739
Glottis, 707
rinia of, 707
Gomphosis, 185
Graafian vesicles, 753, 754
membrana granulosa of, 754
ovicapsule of, 754
structure of, 753
Granules, seminal, 744
Gray matter of cerebellum, 533
of cerebrum, 495, 515
chemical analysis of, 495
of fourth ventricle, 533
of medulla oblongata, 513
of spinal cord, 505
of third ventricle, 528
Greater wings of sphenoid, 74
Groin, 758
cribriform fascia of, 760
cutaneous vessels and nerves
of, 758
region of, 758
superficial fascia of, 758
surgical anatomy of, 758
Groove, auriculo - ventricular,
691
bicipital, 129
cavernous, 73, 100
dental, 649
infra-orbital, 83
lachrymal, 84
mylo-hyoid, 94
nasal, 81
occipital, 69
optic, 73
subclavian, 118
Grooves in the radius, 140
ventricular, 691
Growth of bone, 40
Gubernaculum testis, 745
Gums, 644
Gyri operti, 518
Gyrus fornicatus, 517, 521
Hairs, 606
follicles of, 606
structure of, 606
medulla of, 606
root of, 606
shaft of, 606
sheath of, 606
Ham, region of the, 443
Hamstring tendons, surgical
anatomy of, 340
Hand, arteries of, 411, 414
bones of, 140
development of, 148
fascia of, 349
ligaments of, 217
muscles of, 350
nerves of, from median, 571,
573
from radial, 575
from ulnar, 573, 574
veins of, 466
Hard palate, 652
Harmonia, 185
Havers, glands of, 184
Head, muscles of, 240
veins of, 458
of scapula, 127
of ulna, 135
Heart, 691
annular fibres of auricles, 698
arteries of, 699
auricles of, 691, 692
circular fibres of, 698
component parts of, 691
endocardium, 697
fibres of the auricles, 698
of the ventricles, 698
fibrous rings of, 697
fcetal relics in, 693
infundibulum of, 694
left auricle, 695
ventricle, 696
looped fibres of auricles, 698
lymphatics of, 494, 699
muscular structure of, 698
nerves of, 560, 596, 699
openings into, 693
peculiarities of, in foetus, 699
position of, 691
right auricle, 692
ventricle, 694
Heart —
septum ventriculorum, 694
size and weight, 691
spiral fibres of, 698
structure of, 697
subdivision into cavities, 691
valves of, 693, 694, 695
veins of, 699
vortex of, 698
Helicotrema of cochlea, 640
Helix, 629
fossa of, 629
muscles of, 630
process of, 629
Hernia, congenital, 765
direct inguinal, 761, 765
comparative frequency of,
766
course of, 765
coverings of, 765
diagnosis of, 766
incomplete, 766
femoral, complete, 773
cutaneous vessels and
nerves of, 766
coverings of, 773
descent of, 773
dissection of, 766
incomplete, 773
seat of stricture in, 774
superficial fascia of, 766
surgical anatomy of, 700
varieties of, 773
infantile, 765
inguinal, 758, 764
dissection of, 758
external, 764
internal, 764
surgical anatomy of, 758
oblique inguinal, 764
course of, 764
coverings of, 764
scrotal, 765
Hesselbach's triangle, 765
Hey's ligament, 769
Hiatus Fallopii, 69, 101
Highmore, antrum of, 83
Hilton's muscle, 710
Ililus of kidney, 724
of spleen, 684
Hip joint, 221
muscles of, 334
Hippocampus major, 524
minor, 523
Humerus, 129
anatomical neck, fracture of,
320
articulations of, 133
attachment of muscles to, 133
development of, 132
head of, 129
neck of, 129
nutrient arterv of, 409
shaft of, fracture of, 322
surgical neck, fracture of, 321
tuberosities of, 129
Humors of the eye, 622
Hyaloid membrane of eye, 623
Hymen, 747
Hyoid bone, 111
attachment of muscles to, 112
INDEX.
799
ITyoid bono —
development of, 112
Ileo-c^cal valve, 673
-colic valve, G73
Ileum, 608
Ilium, 149
attachment of musclesto, 155
Impressio colica, 678
renalis, 678
Incisor teeth, 646
of lower jaw, 646
of upper jaw, 646
Incisura cerebelli, anterior, 531
posterior, 531
intertragica, 629
Santorini, 631
Incus, 635
ligament of, 636
suspensory, 636
Infantile hernia, 765
Inferior maxillary bone, 92. See
Jaw, lower,
meatus of nose, 111, 613
turbinated bones, 91
articulations of, 91
development of, 91
Infundibula of kidney, 726
Infundibulum of brain, 628
of cochlea, 639
of ethmoid, 79
of heart, 694
Inlet of pelvis, 155
Innominate bone, 149
articulations of, 155
attachment of muscles to,
155
development of, 154
structure of, 154
Inorganic constituent of bone,
33
Interarticular fibro- cartilage,
183
of jaw, 197
of knee, 225
of pubes, 206
of radio-ulnar joint, 214
of sacro-coccvgeal joint,
205
of scapuloclavicular joint,
209
of sterno-clavicular joint,
208
Intercellular substance of car-
tilage, 182
Intercclumnar fibres, 760
Intercostal spaces, 116
Interlobular biliary plexus, 680
Interpeduncular space of brain,
519
Interstitial lamella;, 36
Intertubular tissue of teeth, 648
Intervertebral notches, 41
substance, 189
Intestine, large, 670
cellular coat of, 674
ca;cum, 670
colon, 672
ileo-caecal valve, 671
mucous membrane of, 674
muscular coat of, 673
Intestine —
rectum, 672
serous coat of, 673
structure of, 673
small, 667
cellular coat of, 668
divisions of, 667
duodenum, 667
ileum, 668
jejunum, 668
glands of, 669
mucous coat of, 668
muscular coat of. 668
serous coat of, 668
simple follicles of, 669
structure of, 668
submucous coat of, 668
valvuloe conniventes, 668
villi of, 668
Intra-cartilaginous ossification,
39
-membranous ossification,
39
Intumescentia gangliformis, 541
Involuntary muscles, 234
Iris, 619
arteries of, 620
structure of, 619
Ischium, 152
attachment of muscles to, 155
Island of Reil, 518
Isthmus of the fauces, 653
of the thyroid gland, 721
Iter ad infundibulum, 528
e tertio ad quartum ventri-
culum,528
Ivory of tooth, 648
Jacob's membrane, 621
Jacobson's nerve, 556
canal for, 71
Jaw, lower, 92
articulations of, 97
attachments of muscles to,
97
changes produced by age
in, 95
development of, 95
ligaments of, 195
oblique line of, 92
rami of, 94
symphysis of, 92
upper. See Superior Maxil-
lary bone.
Jejunum, 668
Joint. See Articulations.
Kerkrino, valves of, 668
Kidney, 724
calyces of, 726
cortical substance of, 724
ducts of, 726
hilus of, 724
infundibula of, 726
lymphatics of, 727
Malpighian bodies of, 726
mammillae of, 725
medullary substance of, 724
nerves of, 727
papillae of, 725
pelvis of, 726
Kidney — ■
pyramids of Ferrcin, 726
of Malpighi, 724
relations of, 724
renal artery, 726
sinus of, 726
tubes of Ferrein, 726
tubuli uriniferi, 725
veins of, 726
weight and dimensions of, 724
Knee-joint, 223
Kurschner, on structure of
heart's valves, 694
Labia cerebri, 521
pudendi majora, 746
minora, 747
lymphatics of, 488
Labyrinth, 637
arteries of, 642
fibro-serous membrane of, 639
membranous, 640
nerves of, 642
veins of, 642
Lachrymal apparatus, 027
bones, 86
articulations of, 86
attachment of muscles to,
86
development of, 86
Lacteals, 493, 069
Lactiferous ducts, 756
Lacuna magna, 733
Lacunae of bone, 36
Lacus lacrymalis, 625, 626
Lamella, articular, 181
of bone, 36
circumferential, 36
horizontal, of ethmoid, 77
interstitial, 36
perpendicular, of ethmoid, 77
Lamina cinerea, 518
cribrosa of sclerotic, 616
denticulate of cochlea, 640
fusca of sclerotic, 015
membranacea, 040
spiralis of cochlea, 040
Laminae of cornea, clastic, 616
of the vertebrae, 41
Laminated tubercle of cerebel-
lum, 531
Laryngis sacculus, 712
Laryngo-tracheotomy, 713, 714
Laryngotomy, 713, 714
Larynx, 703
arteries of, 711
cartilages of, 703
cavity of, 707
glands of, 711
glottis, 707
interior of, 706
ligaments of, 705
lymphatics of, 711
mucous membrane of, 710
muscles of, 708
actions of, 708
nerves of, 711
pouch of, 708
rima glottidis, 707
veins of, 711
ventricle of, 708
800
INDEX.
Larynx —
vocal cords of, false, 707
inferior, 708
superior, 708
true, 708
Lateral ginglymus, 186
masses of ethmoid, 78
Leg, arteries of, 446
bones of, 163
fascia of, 340
deep, 345
ligaments of, 226
lymphatics of, 488
muscles of front of, 341
back of, 343
nerves of, 588
veins of, 473
Lens, crystalline, 623
capsule of, 623
changes produced in by age,
624
structure of, 624
suspensory ligament of, 624
Lesser lachrymal bone, 86
Lieberkuhn, crypts of, 669
Ligament or Ligaments, struc-
ture of, 183
accessory, 211
acromio-clavicular, superior,
208
inferior, 208
alar of knee, 226
of ankle, anterior, 228
lateral, 228
annular of ankle, 348
anterior, 348
external, 348
internal, 348
of radius and ulna, 213
of stapes, 636
of wrist, anterior, 315
posterior, 315
anterior of knee, 223
arcuate, 291
aryteno-epiglottic, 707
astragalo-scaphoid, 2-2
atlo-axoid, anterior, 191
posterior, 192
of bladder, false, 731
true, 730
broad of liver, 676
of uterus, 750
calcaneo-astragaloid exter-
nal, 230
posterior, 230
calcaneocuboid, internal, 231
long, 231
short, 231
superior, 231
calcaneo-scaphoid, inferior,
231
superior, 231
capsular of atlo-axoid, 193
of costo-sternal, 200
of crico-thyroid, 206
of hip, 221
of intercostal, 202
of jaw, 197
of knee, 224
of occipito-atloid, 194
of ribs with spine, 198
Ligament or Ligaments —
of shoulder, 210
of thumb, 218
of vertebrae, 190
carpo-metacarpal, 218
of carpus, 217
central, of spinal cord, 502
check, 195
ciliary of eye, 620
common vertebral, anterior,
188
posterior, 189
conoid, 209
coraco-acromial, 210
-clavicular, 209
-humeral, 211
coracoid, 210
coronary of knee, 226
of liver, 676
costo-clavicular, 208
-sternal, anterior, 200
posterior, 200
-transverse, anterior, 199
middle, 199
posterior, 200
-vertebral, 198
-xiphoid, 201
cotyloid, 222
crico-arytcnoid, 706
-thyroid, 706
crucial of knee, 224
external, 224
internal, 224
cruciform, 193
deltoid, 228
dorsal, of carpo-metacarpal,
218
of carpus, 217
of metacarpus, 219
of metatarsus, 233
tarso-metatarsal, 233
of tarsus, 230
of elbow, 212
anterior, 212
external lateral, 212
internal lateral, 212
posterior, 212
falciform of liver, 676
femoral, 769
gastro-phrenic, 664
Gimbernat's, 281, 760, 770
glenoid, 211
glosso-epiglottidean, 705
Hey's 769
of hip, 221
hyo-epiglottic, 705, 706
ilio-femoral, 222
-lumbar, 203
of incus, 636
interarticular of ribs, 198
interclavicular, 208
intercostal, 201
internal lateral of lower jaw,
196
of knee, 224
interosseous, calcaneo-astra-
galoid, 230
calcaneocuboid, internal,
231
carpal, 217
carpo-metacarpal, 218
Ligament or Ligaments—
metacarpal, 219
metatarsal, 233
radio-ulnar, 214
of ribs, 199
tarsal, 230
tarso-metatarsal, 233
tibio-fibular, inferior, 22T
inter-spinous, 190
inter-transverse, 191
intervertebral, 189
of jaw, lower, 195, 196
lateral, external, 195
internal, 196
of knee, 223
of larynx, 705
extrinsic, 705
intrinsic, 705
lateral of ankle, 228
of bladder, 730
of carpus, 218
of elbow, 212
of jaw, 195
of knee, 224
of liver, 676
of tarso-metatarsal, 233
longitudinal of liver, 676
lumbo-iliac, 203
-sacral, 203
of malleus, 635
metacarpal, 219
metacarpo-phalangeal, 220
anterior, 220
lateral, 220
metatarsal, 233
metatarso-phalangeal, 233
mucosum, 226
nucha?, 270
oblique, 214
obturator, 207
occipito-atloid, anterior, 194
lateral, 194
posterior, 194
-axoid, 195
odontoid, 195
orbicular, 213
of ossicula, 635
of ovary, 755
palmar, 217, 218
palpebral, 626
peritoneal, 662
of patella, 223
of pelvis, 204
of the phalanges of the hand,
220
anterior, 220
lateral, 220
of the foot, 234
of the pinna, 629
plantar, 230, 233
long, 231
posterior of knee, 224
sternal, 203
posticum Winslowii, 224
Poupart's, 281, 760, 769
pterygo-maxillary, 249
pubic, anterior, 206
posterior, 206
superior, 206
pubo-prostatic, 730, 735
radio-carpal, 216
INDEX.
801
Ligament or Ligaments —
radioulnar, anterior, 21-1
middle, 214
posterior, 214
recto-uterine, 750
rhomboid, 208
round, of hip, 222
of liver, GT6
of radius and ulna, 214
of uterus, 755
sacro-coccygeal, anterior, 205
posterior, 205
sacro-iliac. anterior, 204
oblique, 204
posterior, 204
sacro-sciatic, anterior, great-
er, 204
lesser, 204
posterior, 204
sacro-vertebral, 203
of scapula, 210
of shoulder, 210
of stapes, G36
stellate, 198
sterno-clavicular, anterior,
207
posterior, 208
of sternum. 202
stylo-maxillary, 196
subflavous, 190
subpubic, 206
supra-spinous, 190
suspensory, of incus, 636
of lens, 024
of liver, 676
of malleus, 636
of mamma, 294
of penis, 736
of spleen, 684
sutural, 181
tarsal, 180
of eyelids, 626
tarso-metatarsal, 233
teres, of hip. 222
of thumb, 220
thyro-arytcnoid, inferior, 708
superior, 707
-epiglottic, 705, 706
-hyoid, 705
tibio-fibular, 227
-tarsal, 228
transverse of atlas, 193
of hip, 222
of knee, 225
of metacarpus, 219
of scapula, 210
of tibio-fibular, 227
trapezoid, 209
triangular, infrapubian, 781
of urethra, 781
of tympanic bones, 635
of incus, 636
of malleus, 635
of stapes, 636
of urethra, 781
of uterus, 750
of vertebra;, 188
vesico-uterine, 750
of Winslow, 224
of wrist, 216
anterior, 216
51
Ligament or Ligaments —
lateral, external, 216
internal, 216
posterior, 216
of Zinn, 244
Ligamenta alaria, 226
subflava, 190
Ligamentum arcuatum exter-
num, 291
internum, 290
denticulatum, 502
latum pulmonis, 715
patella;, 223
teres of hip, 222
See also Ligaments.
Ligation of arteries. See Ope-
ration.
Limbus luteus, 620
Linea alba, 287
aspera, 160
ilio-pectinea, 153
quadrati, 160
splcndens, 502
Linea; semilunares, 287
transversa; of abdomen, 287
of fourth ventricle, 532
Lingual bone, 111
Linguetta laminosa, 529
Lips, 643
arteries of, 375
structure of, 643
Liquor Cotunni, 640
Morgagnii, 623
Scarpa;, 641
seminis, 744
Lithotomy, parts avoided in, 784
parts concerned in, 783
divided in, 784
Liver, 675
arteries of, 678
changes of position in, 675
distribution of vessels to, in
foetus, 701
ducts of, 680, 681
fibrous coat of, 679
fissures of, 676
of ductus venosus, 677
for gall-bladder. 677
longitudinal, 677
portal, 677
transverse, 677
umbilical, 677
for vena cava, 677
hepatic artery, 678, 679, 680
cells, 679, 680
duct, 679, 681
veins, G78, 679, 680
ligaments of, 675
broad, 676
coronary, 676
falciform. 676
lateral, 676
longitudinal, 676
round, 675, 676
suspensory, 676
lobes of, 677
left, 678
right, 677
lobus caudatus, 678
quadratus, 678
Spigelii, 678
Liver —
lobules of, 679
lymphatics of, 492, 678
nerves of, 678
portal vein, 678, 680
situation, size, and weight, 675
structure of, 678
surfaces and borders of, 675
veins of, 678
Lobes of cerebellum, 531
digastric, 532
inferior, posterior, 532
pneumogastric, 532
slender, 532
subpeduncular, 532
of cerebrum, 517. See Cere-
brum,
of liver, See Liver,
of lung, 718
optic, 529
of prostate, 735
of testis, 742
of thymus, 722
of thyroid, 721
Lobular biliary plexus, 680
Lobule of the ear, 629
Lobules of liver, 679
of lung, 719
Lobuli testis, 742
Lobulus centralis of cerebellum,
531
Lobus caudatus, 678
quadratus, 678
Spigelii, 678
Locus ca;ruleus, 532
niger, 520
perforatus anterior, 519
posterior, 5 1 9
Lower extremity, arteries of,
438
bones of, 149
fascia of, 324
ligaments of, 221
lymphatics of, 488
muscles of, 324
nerves of, 580
veins of, 473
Lower, tubercle of, 693
Lumbar vertebra;, 47
development of, 49
Lungs, 717
air-cells of, 720
bronchial arteries, 720
veins, 720
capillaries of, 720
in foetus, 701
lobes and fissures of, 718
lobules of, 7 1 9
lymphatics of, 494, 721
nerves of, 721
parenchyma of, 719
pulmonary artery, 720
veins, 720
root of, 718
structure of, 719
subdivision of bronchi in, 71 3
weight, color, etc., 719
Lunula; of nails, 605
Lymphatic duct, right. 484
Lymphatic glands, 482
anterior mediastinal, 493
802
INDEX.
Lymphatic glands — '
auricular, posterior, 484
axillary, 487
brachial, 487
bronchial, 494
buccal, 484
cervical, deep, 485
superficial, 486
in front of elbow, 486
gluteal, 489
of head, superficial, 484
iliac, external, 490
internal, 490
inguinal, deep, 489
superficial, 488
intercostal, 493
internal mammary, 493
ischiatic, 489
of large intestine, 493
of lower extremity, 488
lumbar, 490
mammary, 493
mediastinal, posterior. 493
mesenteric, 493
of neck, 485
occipital, 484
parotid, 484
of pelvis, 490
deep, 490
popliteal, deep, 489
radial, 487
sacral, 490
of small intestine, 493
of spleen, 493 •
of stomach, 492
submaxillary, 488
of thorax, 493
tibial, anterior, 488
ulnar, 487
of upper extremity, 486
zygomatic, 484
Lymphatics, 481
coats of, 481
origin of, 481
plexus of, 481
subdivision of, 481
deep, 481
superficial, 481
valves of, 482
vessels and nerves of, 482
abdomen, 490
afferent, 482
arm, 487
bladder, 492
bone, 38
broad ligaments, 492
cardiac, 494
cerebral, 484
cervical, deep, 486
superficial, 486
chest, 494
clitoris, 491
cranium, deep, 485
diaphragm, 494
efferent, 482
face, 484
deep, 485
superficial. 484
Fallopian tubes. 492
gluteal region, 490
Lymphatics —
head, 484
superficial, 484
heart, 494
intercostal, 494
internal mammary, 494
intestines, 493
kidneys, 492, 727
labia, 491
lacteals, 493
large intestine, 493
leg, 489
liver, 492, 678 .
lower extremity, 488, 489
deep, 489
superficial, 489
lung, 494, 721
meningeal, 485
mesentery, 494
mouth, 485
neck, 485
nose, 485
nymphae, 491
oesophagus, 494
ovaries, 492
pancreas, 493
pelvis, 490, 491
penis, 490
perineum, 490
pharynx, 485
pia mater, 485
prostate, 492
radial, 487
rectum, 492
scrotum, 490
small intestine, 493
spleen, 493
stomach, 492
testicle, 492
thoracic duct, 483
thorax, 494
thymic, 494
thyroid, 494
upper extremity, 486
deep, 487, 488
superficial, 487, 488
uterus, 492
vagina, 492
Lyra of fornix, 526
Macula cribrosa, 638
Magnum (os) of carpus, 145
Malar bones, 87
articulations of, 88
attachment of muscles to,
88
development of, 88
Malleolus, external, 169
internal, 167
Malleus, 635
suspensory ligament of, 636
Malpighi, pyramids of, 725
Malpighian bodies of kidney,
726
corpuscles of spleen, 686
relation with arteries, 686
veins, 686
Mamma, 756
areola of, 756
lobules of, 756
mammilla of, 756
Mamma —
nerves of, 757
nipple, 756
structure of, 756
vessels of, 757
Mammary gland. See Gland,
mammary.
Mammilla of breast, 756
of kidney, 725
Manubrium of sternum, 112
of malleus, 635
Marrow of bone, 38
spinal, 502 •
Mastoid cells, openings of, 633
portion of temporal bone, 69,
631
Matrix of nail, 605
Maxillary bone, inferior, 92
superior, 81
Meatus auditorius externus, 69
internus, 70
of nose, inferior, 111, 613
mucous membrane of,
613
middle, 111, 613
mucous membrane of,
613
superior, 110, 613
mucous membrane of,
613
urinarius, female, 747
male, 733, 736
Meckel's ganglion, 550
Mediastinum, 715, 716
anterior, 716
middle, 716
posterior, 715, 716
testis, 741
Medulla oblongata, 510
anterior pyramids of, 511, 512
back of, 512
corpora pyramidalia of, 511
fasciculi graciles of, 511
fissures of, 511
gray matter of, 513
lateral tract of, 511
olivary body, 511
pyramids of, anterior, 511
posterior, 511
restiform bodies, 511
septum of, 513
structure of, 512
Medulla spinalis, 502. Set
Spinal cord.
Medullary canal of bone, 35
membrane of bone, 38
substance of brain, 495
of kidney, 725
of supra-renal capsules, 725
velum, posterior, of cerebel-
lum, 531
Meibomian glands. 626
Membrana fusca, 615
granulosa, 621
limitans, 622
nictitans, 627
pupillaris, 620
sacciformis, 215
tympani, 6:54
structure of, 634
secundaria, 633, 639
INDEX.
803
Membrane of aqueous chamber,
623
arachnoid, cerebral, 508
spinal, 501
choroid, 018
costo-coracoid, 290
crico-thyroid, 700
fenestrated, 359
hyaloid, 023
hyoglossal, 010
Jacob's 021
limiting, 022
pituitary, 013
pupillary, 020
Schneiderian, 013
thyro-hyoid, 705, 700
vitelline, 754
Membranes of spinal cord, 500
of brain, 507
Membranous labyrinth, 040
structure of, 041
portion of urethra, 733
semicircular canals, 041
zone, 040
Meninges, cerebral, 500
spinal, 507
Menisci, 183
Mesentery, 002, 003
M6soc6pliale, 514
Mesocascum, 003
Mesocolon, ascending, 003
descending, 003
sigmoid, 003
transverse, 003, 072
Mesorchium, 745
Mesorectum, 003
Metacarpal bones, 140
Metacarpus, 140
common characters of, 140
development of, 148
peculiar bones of, 140
Metatarsus, 177
bones of, 177
development of, 179
Middle ear or tympanum, 032
Milk teeth, 045, 047
Mitral valve, 097
Modiolus of cochlea, 039
Molar teeth, 040
peculiar, 047
Mons Veneris, 740
Monticulus cerebelli, 531
Morsus diaboli, 7.">2
Motor oculi nerve, 537
Mouth, 043
mucous membrane of, 043
muscles of, 248
Movement admitted in joints,
187
Multicuspidate teeth, 040
Muscles, General Anatomy of,
235
of animal life, 235
aponeuroses of, 237
arrangement of fibres of, 230
bipenniform, 230
bloodvessels of, 230
derivation of names of, 230
fasciculi of, 235
fibrils of, 235
form of, 230
Muscles —
fusiform, 230
insertion of, 237
involuntary, 230
lymphatics of, 230
mode of connection, with
bone, &c, 230
nomenclature of, 230
of organic life, 235
origin of, 237
penniform, 237
primitive fasciculi of, 235
fibrils of, 235
radiated, 237
sarcous elements of, 235
sheath of. 230
size of, 237
striped, 235
structure of, 230
tendons of, 237
unstriped, 235
voluntary, 235
Muscle or Muscles, Descriptive
Anatomy of, 238
of abdomen, 281
abductor indicis, 319
minimi digiti of foot, 351
of hand, 318
pollicis of foot, 351
of hand, 310
accelerator urinae, 778
accessorius ad sacro-lumba-
lem, 270
orbicularis oris, 248
pedis, 270
of acromial region, 299
adductor brevis, 333
longus, 333
magnus, 333
pollicis of hand, 318
of foot, 353
anconeus, 312
anomalus, 240
antitragicus, 030
of anus, 770
of arm, 302
arytacno-epigiottideus infe-
rior, 710
superior, 710
arytaenoideus, 709
attollens aurem, 241
oculi, 244
attrahcns aurem, 242
of auricular region, 241
azygos uvulae, 205
of back, 209
basio-glossus, 201
biceps of arm, 303
of leg, 339
biventer cervicis, 277
brachial region, anterior, 300
posterior, 312
brachialis anticus, 304
buccinator, 249
caninus. 217
cerato-glossus, 201
cervicalis ascendens, 270
of chest, 294
chondro-glossus, 201
ciliary of eye, 020
circumflexus palati, 205
Muscle or Muscles —
coccygeus, 782
cochlcaris, 040
complexus, 277
compressor naris, 240
narium minor. 240
sacculi laryngis, 708, 710
urethra, 733
constrictor isthmi faucium,
205
pharyngis inferior, 202
medius, 203
superior, 203
urethra, 781
coraco-brachialis, 303
corrugator supercilii. 243
cremaster, 702
crico-arytaenoideus lateralis,
709
posticus, 708
crico-thyroid, 708
crureus, 331
deltoid, 299
depressor alae nasi, 240
anguli oris, 248
epiglottidis, 710
labii inferioris, 248
diaphragm, 289
digastric, 259
dilator naris anterior, 240
posterior, 240
dorsum of foot, 350
of epicranial region, 239
erector clitoridis, 780
penis, 779
spinae, 270
of external ear, 241
external sphincter, 770
extensor brevis digitorum,
350
carpi radialis brevior, 311
longior, 310
ulnaris, 312
coccygis, 279
communis digitorum, 312
indicis, 314
longus digitorum, 342
minimi digiti, 312
ossis metacarpi pollicis, 313
primi internodii pollicis.
313
proprius pollicis, 342
secundi internodii pollicis.
313
of eyelids, 242
of face, 240
femoral region, anterior, 327
internal, 332
posterior, 339
fibular region, 347
flexor accessorius, 352
brevis minimi digiti of foot,
353
of hand, 318
brevis digitorum. 351
pollicis of foot, 353
of hand, 317
carpi radialis, 300
ulnaris, 307
digitorum profundus, 303
sublimis, 307
804
INDEX.
Muscle or Muscles —
longus digitorum, 346
pollicis of foot, 346
of hand, 309
ossis metacarpi pollicis,
316
profundus digitorum, 308
sublimis digitorum, 307
of foot, 348
of forearm, 305
gastrocnemius, 343
gemellus inferior, 338
superior, 337
genio-hyo-glossus, 2G0
-hyoid, 259
gluteus maximus, 334
medius, 335
minimus, 336
of gluteal region, 334, 335,
336
gracilis, 332
of hand, 315, 316
of head and face, 238
helicis major, 630
minor, 630
Hilton's, 710
of hip, 334
humeral region, anterior, 302
posterior, 304
hyo-glossus, 260
of hyoid bone and larynx,
256, 258
iliac region, 325
iliacus, 326
ilio-costalis, 276
infra-costal, 289
infra-spinatus, 300
intercostal, 288
external, 288
internal, 288
of intermaxillary region, 248
interossei, 319, 354
dorsal, 319
palmar, 320
plantar, 354
inter-spinales, 279
inter-transversales, 279
labial, 248
of larynx, 705
latissimus dorsi, 270
laxator tympani major, G36
minor, 636
of leg, 340
levator anguli oris, 247
scapulae, 272
ani, 781
glandulae thyroidea?, 721
labii inferioris, 247
superioris, 247
akvque nasi, 246
proprius, 247
proprius alee nasi ante-
rior, 246
posterior, 246
menti, 247
palati, 265
palpebral 243
superioris, 243, 625
prostatas, 735
levatores costarum, 289
lingualis, 261
Muscle or Muscles —
superficialis, 610
of lips, 248
of liver, 678
longissimus dorsi, 276
longus colli, 267
of lower extremity, 324
lumbricales of foot, 352
of hand, 319
masseter, 249
of mouth, 248
multifidus spina?, 278
mylo-hyoid, 259
myrtiformis, 246
naso-labialis, 248
of neck, 252
of nose, 246
oblicpius externus abdominis,
281, 760
internus, 283, 761
ascendens, 283, 761
auris, 631
capitis inferior, 280
superior, 280
cervicis inferior, 280
superior, 280
descendens, 281, 760
oculi inferior, 245
superior, 245
obturator externus, 338
internus, 337
occipito-frontalis, 239
omo-hyoid, 258
opponens minimi digiti, 319
pollicis, 316
orbicularis oris, 248
palpebrarum, 242
of orbit, 243
nalate, 264
palato-glossus, 262, 265
pharyngeus, 265
palmaris brevis, 318
longus, 307
of palpebral region, 242
pectineus, 332
pectoralis major, 294
minor, 296
of penis, 779
of perineum, female, 781
male, 779
peroneus brevis, 347
longus, 347
tertius, 342
of pericranium, 240
of pharynx, 260
of pinna, 630
plantaris, 344
platysma myoides, 253
popliteus, 345
pronator quadratus, 309
radii teres, 306
psoas magnus, 326
parvus, 326
pterygoid, external, 252
internal, 251
pyramidalis abdominis, 287
nasi, 246
pyriformis, 336
quadratus femoris, 338
lumbornm, 287
menti, 248
Muscle or Muscles — .
quadriceps extensor cruris,
330
radial region, 310
rectus abdominis, 286
capitis anticus major, 266
minor, 267
posticus major, 279
minor, 279
femoris, 330
lateralis, 267
oculi, 244
externus, 244
inferior, 244
internus, 244
superior, 244
retrahens aurem, 242
rhomboideus, 246
major, 273
minor, 272
risorius of Santorini, 249
rotatores spina?, 278
sacro-lumbalis, 276
sartorius, 329
scalenus anticus, 268
medius, 268
posticus, 268
scapular region, anterior, 299
posterior, 300
semi-membranosus, 340
serratus magnus, 298
posticus inferior, 274
superior, 273
semi-spinalis colli, 278
dorsi, 278
semi4endinosus, 339
sole of foot. 350
first layer, 350
second layer, 352
third layer, 353
soleus, 344
sphincter ani, external, 77G
internal, 776
vagina;, 780
spinalis cervicis, 277
dorsi, 277
splenitis, 274
capitis, 274
colli, 274
stapedius, 636
sterno-cleido-mastoid, 251
-hyoid, 256
-thyroid, 257
stylo-glossus, 261
-hyoid, 259
-pharyngeus. 2G3
subanconeus, 305
subclavius, 296
subcrureus, 331
subscapularis. 299
supinator brevis, 313
longus, 310
Bupra-epinales. 279
supra-spinatus', 300
temporal, 251
tensor palati, 265
tarsi, 243
tympani. 636
vagina? femoris, 329
teres major, 301
minor, 301
INDEX.
805
Muscle or Muscles —
of thigh. 327
of thoracic region, anterior,
294
lateral, 298
of thorax, 288
of thumb, 316
thyro-arytamoideus, 709
-epiglottideus, 710
-hyoid, 258
tibialis anticus, 341
posticus, 340
tibio-fibular region, anterior,
341
posterior, 343
of tongue, 2G0
trachelo-mastoid, 277
tragicus, 630
transvcrsalis abdominis, 284,
762
colli, 277
transversus auriculae, 630
pedis, 353
perinei, 779
in female, 780
trapezius, 269
triangularis sterni, 289
triceps extensor cruris, 330
cubiti, 304
femoralis, 331
of trunk, 269
of tympanum, 636
of upper extremity, 293
surgical anatomy of, 320
of ureters, 731
of urethra, 778
vastus externus, 330
internus, 330
vertebral region, anterior, 215
lateral, 217
zygomaticus major, 247
minor, 247
Musculi papillares of left ven-
tricle, 697
of right ventricle, 695
pectinati, in left auricle, 696
in right auricle, 693
Musculus. See Muscle.
Nails, 605
chemical composition of, 606
lunula of, 605
matrix of. 605
root of, 605
structure of, 605
Nares, anterior, 109
posterior, 106, 656
septum of, 110, 612
Nasal bones, 81
articulations of, 81
development of, 81
fossae, 109, 613
arteries of, 614
mucous membrane of, 613
nerves of, 614
veins of, 614
Nates of brain, 531
Navicular bone, 141. 175
Neck, muscles of, 253
triangle of, anterior, 382
posterior, 384
Neck —
surgical anatomy of, 382
veins of, 458
Nerve or Nerves, 496
General Anatomy of —
afferent, 500
centrifugal, 500
centripetal, 500
cerebro-spinal, 498
composition of, 498
junction of funiculi of,
498
neurilemma of, 498
origin of, 498
apparent, 499, 500
real, 500
plexus of, 498
sheath of, 498
structure of, 498
subdivision of, 497
termination of, 498
vessels of, 498
cells, 497
compound, 535, 545
corpuscles, 497
efferent, 500
excito-motory, 500
fibres, 496
mixed, 535
of motion, 535
motor, 500
reflex, 500
sensitive, 500
of special sense, 535
spinal, roots of, 560
sympathetic, 592
Descriptive Anatomy of —
abducens, 539
accessory obturator, 582
spinal, 560
acromial, 564
of arachnoid, 509
articular, of elbow, 573
hip, 482, 588
knee, 582, 584, 590
shoulder-joint, 568, 569
wrist, 573
auditory, 537, 642
auricular, of auricularis
magnus, 564
of auriculo-temporal, 250
posterior, from facial, 542
of second cervical, 566
of small occipital, 564
of vagus, 558
auricularis magnus, 564
axillary, 565
of bone, 38
buccal, 550
of facial, 543
of inferior maxillary, 550
cardiac, 596
inferior, 596
middle, 596
posterior, 566
of pneumogastric, 569
superior, 596
cardiacus magnus, 596
minor, 596
carotid, §57
cavernous, large, 691
Nerve or Nerves —
cavernous, small, 601
of penis, 601
cervical, roots of, 562
anterior branches of, 563
posterior branches of, 56(5
superficial branches of, 564
cervico-facial, 543
chorda tympani, 542, 637
ciliary, long, 547
short, 548
circumflex, 569
clavicular, 564
coccygeal, 584
anterior, 585
posterior, 585
cochlear, 642
communicans noni, 565
peronei, 589
of Cotunnius. 553
cranial. See Cranial nerves,
crural, 580
anterior, 582
cutaneous, of abdomen, ante-
rior, 579
lateral, 579
accessory obturator, 582
of arm, external, 569
internal, 570
lesser internal, 570
of buttock and thigh, 580
of cervical plexus, 564
circumflex, 569
coccygeal, 584
crural, anterior, 582
dorsal nerves, 576
dorsalis pedis, 586
hemorrhoidal, inferior, 586
ilio-hypogastric, 580
-inguinal, 580
of inguinal region, 758
intercostal, 577
of ischio-rectal region, 777
lateral of dorsal, 578
of intercostal, 577
lumbar, 578
median, 571
musculo-cutaneous, 5G9,
591
-spiral, 575
obturator, 580
palmar, 575
of patella, 583
perineal, 586
peroneal, 590
plantar, 589
popliteal, external, 590
internal, 588
radial, 575
sacral, 584
sciatic, lesser, 588
small, 588
of thigh, external, 580
internal, 583
middle, 583
of thorax, anterior, 577
lateral, 577
tibial, anterior, 591
posterior, 589
ulnar, 573
cutaneus patella?, 583
806
INDEX.
Nerve or Nerves —
dental, anterior, 549, 614
inferior, 551
posterior, 549
descendens noni, 545
digastric, from facial, 543
digital of foot, dorsal, 590, 591
plantar, 589
of hand, dorsal, 574, 575
palmar, median, 573
radial, 575
ulnar, 574
dorsal, 576, 577
anterior branches of, 576
peculiar, 577
posterior branches of,576
roots of, 576
of penis, 586
dorsi-lumbar, 578
-spinal, 576
of dura mater, 507
eighth pair, 555
of eyeball, 625
facial, 540
branches of, 541
communications of, 541
in temporal bone, 540
of femoral artery, 580
fifth, 545
ganglia connected with, 551
fourth, 538
frontal, 546
ganglionic branch of nasal,
547
gastric branches of vagus, 560
genital, 580
genito-crural, 580
glosso-pharyngeal, 555
gluteal, inferior, 588
superior, 586
gustatory, 550
of heart, 564, 596, 699
hemorrhoidal, inferior, 586
hepatic, 599, 678
hypogastric, 580
hypoglossal, 544
iliac, 580
ilio-hypogastric, 579
-inguinal, 580
incisor, 563
infra-maxillary, 543
of facial, 543
-orbital of facial. 543
-trochlear, 547
intercostal, 576
lower, 577
upper, 576
intercosto-humeral, 577
interosseous, anterior, 571
posterior, 575
of intestines, 599
'ischiadic, great, 588
small, 586
Jacobson's, 556, 637
of kidney, 727
labial, 549
of labyrinth, 642
lachrymal, 546
of Lancisi, 522
large cavernous, 601
laryngeal, external, 559
Nerve or Nerves —
laryngeal, inferior, 559
internal, 559
recurrent, 559
superior, 559
from sympathetic, 594
lesser sciatic, 586
splanchnic, 598
lingual, of fifth, 550
of glosso-pharyngeal, 557
long saphenous, 583
lumbar, 578
anterior branches of, 578
posterior branches of, 578
roots of, 578
lumbo-sacral, 578
malar branch of facial, 543
of orbital nerve, 548
masseteric, 549
mastoid, 564
maxillary, inferior, 549
superior, 547
median, 571
mental, 551
motor oculi, common, 537
external, 539
musculo-cutaneous of arm,
569
inferior, 580
from peroneal, 591
superior, 579
musculo-spiral, 574
mylo-hyoid, 551
nasal, from Meckel's gan-
glion, 553
of ophthalmic, 547, 614
from superior maxillary,
549
from Yidian. 553
naso-palatine, 553, 614
ninth, 544
obturator, 580
accessory, 582
occipital of facial, 543
great, 566
small, 564
of third cervical, 566
occipitalis major, 566
minor, 564
oesophageal, 560
olfactory, 518, 614
peculiarities of, 476
ophthalmic, 546
optic, 536
orbital, 548
relations of, 539
in cavernous sinus, 540
in orbit, 540
in sphenoidal fissure, 540
palatine, 552
anterior, 552
external, 552
large, 552, 614
middle, 552
posterior, 553
small, 553
palmar cutaneous, 571, 574
deep, 573
of median, 571
superficial, 573
ulnar, 574
Nerve or Nerves —
palpebral, 549
parotid, 550
par vagum, 557
pathetic, 538
perforans Gasserii, 569
perineal, 586
superficial, 586
peroneal, 553, 590
petrosal, great, 551
large, 541, 553
small, superficial, 541
superficial external, 541,
553
from Vidian, 553
petrosus superficialis major,
553
pharyngeal, from external la-
ryngeal, 558
from glosso-pharyngeal,
557
from Meckel's ganglion.
554
from pneumogastric, 558
from sympathetic, 594
phrenic, 565
plantar, cutaneous, 589
external, 590
internal, 589
pneumogastric, 557
popliteal, external, 590
internal, 588
portio dura, 540
inter duram et mollem, 540
mollis, 537
pterygoid, 550
pterygopalatine, 553, 554
pudendal, inferior, 588
pudic, 586
pulmonary, anterior, 559
posterior, 560
from vagus, 559
radial, 575
recurrent laryngeal, 559 -
to tentorium, 539
renal splanchnic, 598
respiratory, external, 568
internal, 565
sacral, 584
anterior branches of, 585
posterior branches of, 584
roots of, 584
saphenous, external, 589
internal. 583
long, 583
short, 589
sciatic, great, 588
lesser, 586
small, 586
seventh, 537, 540
sixth, 539
spermatic, 599
spheno-palatine, 549
spinal. See Spinal nerves.
accessory, 560
splanchnic, great, 597
lesser, 598
renal, 598
smallest, 598
splenic, 599
sternal, 564
INDEX.
801
Nerve or Nerves —
stylohyoid of facial, 543
subclavian, 5G8
suboccipital, 562
posterior branch of, 566
subscapular, 569
superficialis colli, 564
cordis, 596
supra-clavicular, 564
-maxillary of facial, 543
-orbital, 547
-scapular, 568
-trochlear, 546
sympathetic, cephalic portion
of, 594
cervical portion of, 594
cranial portion of, 594
lumbar portion of, 600
pelvic portion of. 600
thoracic portion of, 599
tarsal, 591
temporal, of auriculo-tempo-
ral, 550
deep, 549
of facial, 543
of orbital nerve, 548
temporo-facial, 543
-malar or orbital, 548
third or motor oculi, 537
thoracic, anterior, 568
cardiac, 559
long, 568
posterior, 568
thyro-hyoid, 545
tibial, anterior, 590
posterior, 589
of tongue, 611
tonsillar, 557
trifacial, 545
trigeminus, 545
trochlear, 538
tympanic of facial, 541
of glosso-pharyngeal, 556,
037
ulnar. 573
uterine, 601 ,
vaginal, 601
vagus, 557
branches of, 558
ganglion of root of, 557
of trunk of, 557
vestibular. 642
Vidian, 553, 614
of Wrisberg, 570
Nervi nervorum, 499
Nervous substance, chemical
analysis of, 495
microscopic appearance of,
496
Nervous System, General Ana-
tomy of. 495
of animal life, 594
cerebro-spinal axis, 495
cortical substance, 495
division of, 495
fibrous nervous matter, 495
ganglia, 497
gray or cineritious substance,
495
nerves, 497
of organic life, 495
Nervous System —
sympathetic, 499
composition of, 499
gelatinous fibres of, 499
structure of, 499
tubular fibres of, 499
vesicular matter, 495
white or medullary substance
of, 495
Neurilemma, 498
of cord, 502
Nidus hirundinis, 531
Nipple, 756
Nodule of cerebellum, 531
Noduli Arantii, 695
Nodulus, 531
Nose, 611
arteries of, 613
bones of, 81
cartilages of, 612
of septum of, 612
fossae of, 109, 613
mucous membrane of, 613
muscles of, 246, 612
nerves of, 613
veins of, 435, 613
Notch, cotyloid, 153
ethmoidal, 77
intercondyloid, 162
nasal, 64
pterygoid, 75
sacro-sciatic, greater, 152
lesser, 152
sigmoid, 95
spheno-palatine, 91
supra-orbital, 64
-scapular, 126
Nuck, canal of, 745, 755
Nummular layer of retina, 621
Nyniphae, 747
lymphatics of, 491
Oblique inguinal hernia. See
Hernia,
line of the clavicle, 121
of lower jaw, 93
of radius, 139
Occipital bone, 57
articulations of, 61
attachment of muscles to,
61
crests of, 58
development of, 61
structure of, 60
(Esophagus, 656
lymphatics of, 494
relations of, in neck, 657
in thorax, 657
structure of, 657
surgical anatomy of, 657
Oesterlen, on supra-renal cap-
sules, 728
Olfactory bulb. See Bulb, ol-
factory,
nerve. See Nerve, olfactory.
Olivary bodies of medulla ob-
longata, 511, 512
Omenta, 662
Omentum, gastro-colic, 662
gastro-hepatic, 660, 662
-splenic, 662, 684
Omentum —
great, 662
lesser, 660, 662
sac of, 661
Opening, aortic, in diaphragm,
291
in left ventricle. 697
caval in diaphragm, 291
of coronary sinus, 693
of inferior cava, 693
left auriculo-ventricular, 690,
697
oesophageal in diaphragm,
291
of pulmonary artery, 694
veins, 696
right auriculo-ventricular,693
saphenous, 769
of superior cava, 693
Operation for club-foot, 348
of laryngotomy, 714
of laryngo-tracheotomy, 714
ligation of the anterior tibial,
447
over instep, 447
in lower third of leg, 447
in upper part of leg, 447
axillary artery, 406
brachial artery, 408
common carotid artery, 371
above omo-hyoid, 371
below omo-hyoid, 371
iliac artery, 429
dorsalis pedis artery, 449
external carotid, 372
iliac artery, 437
femoral artery, 440
innominate artery, 367
internal iliac artery, 431
lingual artery, 374
popliteal artery, 445
in lower part of its
course, 445
in upper part, 445
posterior tibial, 450
at ankle, 451
in lower third of leg, 451
in middle of leg, 451
radial artery, 411
subclavian artery, 394
superior thyroid artery, 373
ulnar artery, 414
of lithotomy, 783
of cesophagotomy, 657
of staphylorraphy, 266
for strabismus, 245
tracheotomy, 714
for wryneck, 256
Opercula of dental grooves
650
Optic commissure. See Com
missure. optic
lobes. See Lobes, optic.
Ora serrata, 620
Orbicular bone, 635
Orbits, 108
arteries of, 387
muscles of, 243
relation of nerves in, 5-10
Organs of circulation, 691
of deglutition, 056
808
INDEX.
Organs —
ot' digestion, 643
of generation, female, 746
male, 735
of respiration, 703
of sense, 602
urinary, 724
of voice, 703 *
Organic constituent of bone, 33
Orifice, auriculo - ventricular,
692, 694
oesophageal, of stomach,
663
of prostatic ducts, 733
pyloric, of stomach, 663
of uterus, 750
of vagina, 747
See also Openings, Apertures,
and Ostium.
Os calcis, 170
hyoides, 111
innominatum, 149
magnum of carpus, 145
orbiculare, 635
planum, 78
See also Bone.
uteri, 750
Ossa triquetra, 80
Ossicles of ear, 634
Ossicula of tympanum, 634
ligaments of. 635
Ossification of bone, 38
intramembranous, 39
intracartilaginous, 39
of spine, progress in, 49
period of, 39
Osteo-dentine, 649
Osteology, 33
Ostium abdominale of Fallopian
tube, 752
uteri internum, 750
uterinum, 750
Otoliths, 642
Outlet of pelvis, 157
Ovary, 752
corpus luteum of, 754
Graafian vesicles of, 753
ligament of, 755
lymphatics of, 492
nerves of, 755
ovisacs of, 753
shape, position, and dimen-
sions of, 753
situation of, in foetus, 755
stroma of, 753
structure of, 753
tunica albuginca of, 753
vessels of, 755
Ovicapsule of Graafian vesicle,
754
( Oviducts, 752
Ovisacs of ovary, 753
Ovula of Naboth, 751
Ovum, 754
discharge of, 754
discus proligerus, 754
germinal spot, 754
vesicle, 754
vitelline membrane of, 754
yolk of, 754
zona pellucida, 754
Pacchionian' depressions, 62
Palate, 652
arches of, 652
hard, 652
muscles of, 264
pillars of, 653
soft, 652
bone, 88
articulations of, 90
attachment of muscles to,
91
development of, 90
Palmar arch. See Arch, palmar.
Palpebrae, 626
Pampiniform plexus of veins,
755
Pancreas, 682
duct of, 683
structure of, 684
vessels and nerves of. 684
Papilla, lacrymalis, 625
Papillae, conjunctival, 627
of kidney, 725
of skin, 603
of tongue, 609
circumvallatae, 609
conicse, 609
filiformes, 609
fungiformes, 609
maximae, 609
media;, 609
minimae, 609
structure of, 610
of tooth, 649
Papillary stage of development
of teeth, 649
Par vagum, 558
Parietal bones, 61
articulations of, 63
attachment of muscles to,
63
development of, 63
Parotid gland, 653
accessory portion of, 654
duct of, 654
nerves of, 655
vessels of, 655
Patella, 164
articulations of, 164
attachment of muscles to, 164
development of, 164
fracture of. 356
structure of, 164
Pecquet, cistern of, 483
reservoir of, 483
Pectiniform septum, 737
Pectoral region, dissection of,
293
Pedicles of a vertebra, 41
Peduncles of cerebellum, 533
of cerebrum, 519
of corpus callosum, 522
of pineal gland, 532
Pelvic fascia. See Fascia, pelvic.
bones. 155. See Pelvis.
Pelvis, 155, 728
arteries of, 429
articulation of, 204
with spine, 203
axes of, 157
boundaries of, 728
Pelvis —
brim of, 115
cavity of, 156, 728
diameters of, 155
false, 155
inlet of, 155
ligaments of, 204
lymphatics of, 490
male and female, differ-
ences of, 158
outlet of, 157
position of, 157
of viscera at outlet of,782
true, 155
of kidney, 726
Penis, 736
arteries of, 738
body of, 736
corpora cavernosa, 737
corpus spongiosum, 737
dorsal artery of, 434
nerve of, 586
extremity of, 736
glans, 7H6
lymphatics of. 490, 738
muscles of, 779
nerves of, 591, 738
prepuce of, 736
root of, 736
suspensory ligament of, 736
Penniform muscles, 236
Perforans Casserii nerve, 569
Perforated space, anterior, 519
posterior, 519
Perforating arteries, 413
from mammary artery, 400
from plantar, 452
from profunda, 443
inferior, 443
middle, 443
superior, 443
Pericardium, 689
relations of, 689
structure of, 690
fibrous layer of, 690
serous layer of, 690
vessels of, 691
Perilymph, 640
Perineum, 777
abnormal course of arteries
in, 785
deep boundaries of, 777
fascia, deep, 780
superficial, 777
lymphatics of, 483
muscles of, 778
surgical anatomy of, 775
Perineal space, 777
Periosteum, 38
Peritoneum, 660
folds of, 662
lesser cavity of, 661
ligaments of, 662
mesenteries of, 662
omenta of, 662
reflections of, 660
Pes accessorius, 525
hippocampi, 525
Petit, canal of, 624
Petrous portion of temporal
bone, 69
IXPEX.
8«0
Peyer'a glands, 070
Phalanges of foot, 178
articulations of, 234
development of, 179
of hand, 147
a rt it- ulations of, 220
development of, 148
Pharynx, C.">6
aponeurosis of, G56
arteries of, 378
mucous membrane of, 656
muscles of, 262
openings into, G5G
structure of, 656
Phlebolites, 475
Pia mater of brain, 509
vessels and nerves of, 509
of oord, 502
structure of, 502
testis, 741
Pigment cells of iris, 620
Pigmentary layer of choroid,
618
Pillars of external abdominal
ring, 760
of diaphragm, 561
of fauces, 653
of fornix, 526
Pineal gland, 528
peduncles of, 528
Pinna of ear, 628
cartilage of, 629
ligaments of, 629
muscles of, 630
nerves of, 631
structure of, 629
vessels of, 631
Pisiform bone, 143
Pituitary body, 519
Plate, cribriform of ethmoid, 77
external pterygoid, 75
perpendicular, of ethmoid,
77
Pleura. 715
cavity of, 715
parietal layer of, 715
reflections of, 715
vessels and nerves of, 716
visceral layer of, 715
costalis, 715
pulmonalis, 715
Pleurae, 715
Plexus of Nerves, 49o
aortic, 599
brachial, 566
branches above clavi-
cle, 567
below clavicle, 568
cardiac, anterior, 597
deep. 596
great, 596
superficial, 597
carotid. 595
external, 594
cavernous. 595
cerebral, 595
cervical, 563
deep branches of, 565
posterior, 564
superficial branches
of, 564
Plexus of Ncrves-
coeliac, 599
colic, left, 599
middle, 599
right, 599
coronary, anterior, 597
posterior, 597
cystic, 699
diaphragmatic, 598
epigastric, 598
facial, 594
gastric, 599
gastro-duodcnal, 599
epiploic, 599
left, 599
great cardiac, 596
hemorrhoidal inferior,
601
superior, 599
hepatic, 601
hypogastric, 600
inferior, 600
ileo-colic, 599
infra-orbital, 550
lumbar, 578
branches of, 579
magnus profundus, 596
meningeal, 595
mesenteric, inferior, 599
superior, 599
oesophageal, 560
ophthalmic, 595
ovarian. 599
pancreatic, 599
pancreatico-duodcnal,
599
patellar, 584
pelvic, 600
pharyngeal, 561, 595
phrenic, 598
prostatic, 601
pulmonary, anterior, 560
posterior, 560
pyloric, 599 '
renal, 598 '
sacral, 585
sigmoid. 599
solar, 598
spermatic, 599
splenic, 599
superficial cardiac. 597
supra-renal, 598
tonsillar, 557
tympanic, 561, 637
vaginal, 601
vertebral, 596
vesical, 601
of Yeins, 455
choroid. See Choroid,
hemorrhoidal, 475
ovarian. 476
pampiniform, 476, 755
prostatic, 475
pterygoid, 459
spermatic, 476
thyroid, 658
uterine, 475
vaginal, 475
of portal vein, 679
vesico-prostatic, 475
Plica semilunaris, 627
Points of ossification, 38
Pomum Adami, 703
Pons hepatis, (JT7
Tarini, 519
Varolii, 514
longitudinal fibres of, 514
septum of, 515
structure of, 514
transverse fibres of, 514
Popliteal space. See Space,
popliteal.
Pores of the skin, 607
Portio dura of seventh nerve,
540
inter duram et mollem, 540
mollis, 577
Porus opticus of sclerotic, 616
Pott's fracture, 357
Pouches, laryngeal, 708
Poupart's ligament, 281, 760,
769
Praeputium clitcridis, 747
Prepuce, 736
Process or Processes, acro-
mion, 126
fracture of, 321
alveolar, 85
angular, external, 64
internal, 65
auditory, 69
basilar, 59
ciliary, 618
structure of, 619
clinoid, anterior, 75
middle, 73
posterior, 73
cochleariform, 634
condyloid of lower jaw, 95
coracoid, 127
fracture of, 321
coronoid, of lower jaw, 94
of ulna, 135
fracture of, 322
ethmoidal, of inferior turbi
nated, 91
falciform, 769
frontal, of malar, 87
hamular, of cochlea, 640
of lachrymal, 86
of sphenoid, 75
of helix, 629
of Ingrassias, 75
jugular, 59
lachrymal, of inferior turbi
nated bone, 91
malar of superior maxillarv-
84
mastoid, 69
maxillary, of inferior turbi-
nated, 91
of malar bone, 88
mental, 92
nasal. 84
odontoid, of axis, 44
olecranon. 135
fracture of, 322
olivary, 73
orbital, of frontal, 65
of malar, 87
of palate, 89
of superior mayulary, 82
810
INDEX.
^Process or Processes —
palate, 88
palatine, of superior maxil-
lary, 85
pterygoid, of palate bone, 89
of sphenoid, 75
sphenoidal, of palate, 90
spinous, of ilium, 150
of sphenoid, 74
of tibia, 1G5
of vertebra?, 41
styloid, of radius, 139
of temporal, 71
of ulna, 136
transverse, of vertebra, 41
unciform, 145
of ethmoid, 78
vaginal of sphenoid, 74
of temporal, 71
vermiform of cerebellum, infe-
rior, 531
superior, 530
zygomatic, 67
Processus ad medullam, 534
ad pontem, 534
ad testes, 529
brevis, of malleus, 635
caudatus, 629
clavatus, 512
cochleariformis, 71, 634
e cerebello ad testes, 529,
533
gracilis, of malleus, 635
Promontory of sacrum, 50
of tympanum, 633
Prostate gland, 735, 782
lobes of, 735
levator muscle of, 735, 782
position of, 735, 782
secretion from, 736
size and shape of, 735
structure of, 735
surgical anatomy of, 782
vessels and nerves of, 736
Prostatic fluid, 736
secretion, 736
Protuberance, occipital, exter-
nal, 58
internal, 60
Pubes, 153
articulations of, 205
attachment of muscles to, 155
development of, 154
structure of, 154
symphysis of, 153
Pudendum, 746
Puncta lacrymalia, 625
vasculosa, 520
Pulp cavity of tooth, 648
development of, 648
dental, 050
Pupil of eye, 619
dilator muscle of, 620
membrane of, 620
sphincter muscle of, 620
Pylorus, 665
Pyramid of cerebellum, 531
of thyroid gland, 721
of tympanum, 633
in vestibule of ear, G38
Pyramids, anterior, 511
Pyramids, anterior —
decussation of, 51 1
of Ferrein, 726
of Malpighi, 725
posterior, 511
of the spine, 55
Qcadrigeminal bodies, 529
Radiating fibres of retina, 622
Radius, 138
articulations of, 140
development of, 140
fracture of, 323
of lower end of, 324
of neck of, 323
of shaft of, 323
muscles attached to, 140
structure of, 140
and ulna, fracture of, 323
Ramus of ischium, 153
of lower jaw, 94
of pubes, 153
Raphe of corpus callosum, 522
of palate, 652
of perineum, 777
of tongue, 609
Receptaculum chyli, 481
Rectum, 672
columns of, 673
folds of, 674
lymphatics of, 492
relations of, in female, 749
male, 672
surgical anatomy of, 783
Region of abdomen, 281, 658
acromial, muscles of, 299
auricular, muscles of, 241
of back, muscles of, 269
brachial, anterior, muscles of,
306, 308
posterior, 312, 313
cervical, superficial, muscles
of, 253
diaphragmatic, 289
dorsal, of foot, muscles of,
350
epicranial, muscles of 239
epigastric, 659
femoral, anterior, muscles of,
327
internal, 332
posterior, 339
fibular, 347
foot, dorsum of, 350
sole of, 350
gluteal, lymphatics of, 435
muscles of, 334
groin, 758
of hand, muscles of, 316
humeral, anterior, 302
posterior, 304
hypochondriac, 659
left, 659
right, 659
hypogastric, 659
iliac, muscles of, 325
infrahyoid, muscles of, 256
inguinal, 659, 758
left, 659
right, 659
Region —
intermaxillary, muscles of,
248
ischio-rectal, surgical anato-
my of, 775
laryngotracheal. surgical
anatomy of, 713
lateral, of skull, 105
lingual, muscles of, 260
lumbar, 659
left, 659
right, 659
maxillary, inferior, muscles
of, 247
superior, muscles of, 247
nasal, muscles of, 246
orbital, muscles of, 243
palatal, muscles of, 264
palmar, middle, muscles of,
319
palpebral, muscles of, 242
pectoral, muscles of, 293
of perineum, 777
pharyngeal, muscles of, 262
plantar, muscles of, 350
popliteal, 443
pterygo - maxillary, muscles
of, 251
pubic, 659
radial, muscles of, 310, 316
scapular, anterior, muscles
of, 299
posterior, 300
Scarpa's triangle, 4",8
of skull, anterior, 106
supra-hyoid, muscles of, 258
temporo- maxillary, muscles
of, 249
thoracic, muscles of, 288, 294,
298
anterior, 294
lateral, 298
tibio-fibular, anterior, 341
posterior, 343, 345
ulnar, muscles of, 318
umbilical, 659
vertebral, anterior, muscles
of, 266
lateral, 268
Reservoir of Pecquet, 483
of thymus, 722
Respiration, organs of, 717
Restiform bodies of medulla
oblongata, 511, 513
Rete mucosum of skin, 604
testis, 742
Reticular cartilage, 182
Retina, 620
arteria centralis of, 390, 622
external layer of, 621
fovea centralis of, 621
granular layer of, 621
internal layer of, 621
Jacob's membrane of, 621
limbus luteus of, 625
membrana limitans of, 622
middle layer of, 621
nervous layer of, 621
nummular layer of, 621
radiating fibres of, 622
structure of. 621
INDEX.
811
Retina —
yellow spot of, G21
Retinacula of ileo-caecal valve,
671
Rhomboid impression, 122
Bibs, 116
attachment of muscles to,
118
common characters of, 117
development of, 118
false, 116
floating, 116
ligaments of, 198
peculiar, 118
structure of, 118
true, 116
vertebral, 116
vertebro-costal, 116
-sternal, 116
Rickets, 34
Ridge, internal occipital, 60
mylo-hyoidean, 93
pterygoid, 74
superciliary, 64
temporal, 64
Rima glottidis, 707
Ring, abdominal, external, 282,
760
internal. 763
crural, 771
femoral, 771
position of parts around,
771
fibrous, of heart, 697
Root of lung, 719
of spinal nerves, 561
of teeth, 645
of zygomatic process, 67
Rostrum of corpus callosum,
521
of sphenoid bone, 74
Rotation, 187
Rugae of stomach, 666
of vagina, 749
Rupture of urethra, course
taken by urine in, 778
Sac, dental, 650
lachrymal, 628
structure of, 650
of omentum, 622
Sacculus laryngis, 707, 708
of vestibule, 641
Sacrum, 50
articulations of, 54
attachment of muscles to,
54
cornua of, 51
development of, 54
peculiarities of, 53
in female, 53
in male, 53
structure of, 53
Salivary glands, 653
structure of, 666
Santorini, cartilages of, 705
Sarcolemma, 235
Sarcous elements of muscle,
235
Scala tympani of cochlea, 640
vestibuli of cochlea, 640
Scake of cochlea. 640
Scaphoid bone of foot, 175
of hand, 141
Scapula, 123
articulations of, 128
attachment of muscles to, 128
development of, 127
dorsum of, 124
glenoid cavity of, 127
ligaments of, 210
muscles of, 299
spine of, 126
structure of, 127
venter of, 123
Scarfskin, 604
Scarpa's triangle, 438
Schindylesis, 185
Schneiderian membrane, 613
Schreger's analysis of bone, 34
Schwann, white substance of,
496
Sclerotic, 615
structure of, 616
vessels and nerves of, 616
Scrotal hernia. See Hernia,
scrotal.
Scrotum, 739
dartos of, 739
lymphatics of, 490
nerves of, 739
septum of, 739
structure of, 739
vessels of, 739
Sella turcica, 73, 100
Semen, 744
liquor seminis of, 744
seminal granules of, 744
spermatozoa of, 744
Semicircular canals, 638
external, 638
horizontal, 638
membranous, 641
posterior, 638
superior, 638
Semilunar bone, 141
valves. See Valves, Semi-
lunar.
Seminal vesicles. See Vesi-
cuhe seminales.
Seminiferous tubes, 742
Senac, on structure of heart's
valves, 694
Senses, organs of the, 602
Septum auricularum. 691, 695
between bronchi, 712
crurale, 772
lucidum, 525
of medulla oblongata, 513
of nose, 110
cartilage of, 612
pectiniforme, 737
of pons Varolii, 515
scroti, 739
subarachnoid, 501
of tongue, 610
ventriculorum, 694
Sesamoid bones, 179
Shaft of a bone, structure of, 35
Sheath of arteries, 360
crural, 770
femoral, 770
Sheath — »
of muscles, 236
of nerves, 498
Shoulder, 121
Shoulder-joint, 210
muscles of, 299
vessels and nerves of, 211
Sigmoid flexure. See Colon.
Simon, on supra-renal capsules.
728
Sinus, cavernous, 465
circular, 465
circularis iridis, 620
coronary, 479, 693
opening of, in heart, 693
of dura mater, 463
of jugular vein, 461
of kidney, 724
lateral, 464
longitudinal, inferior, 4G4
superior, 463
maxillary, 84
occipital, 464
petrosal, inferior, 466
superior, 466
pocularis, 733
prostatic, 733
of right auricle, 691
of left, 695
straight, 464
transverse, 466
Sinuses, 455, 463
of the aorta, 362, 695, 697
confluence of the, i64
ethmoidal, 78
frontal, 66
maxillary, 84
pulmonary, 695
sphenoidal, 73
of Valsalva, aortic, 362, 697
pulmonary, 695
Skeleton, 33
number of pieces in, 40
Skin, anatomy of, 602
appendages of, 605
areolae of, 603
arteries of, 605
color of, 605
corium of, 603
cuticle of, 604
derma of, 602
epidermis of, 604
furrows of, 604
hairs, 606
lymphatics of, 605
muscular fibres of, 603
nails, 605
nerves of, 605
papillary layer of, 603
rete mucosum of, 604
sebaceous glands of, 607
sudoriferous or sweat gland»
607
true, 602
vessels of, 605
Skull, 57, 98
anterior region of, 106
base of, 99
bones of, 57
cerebral surface of, 100
external surface, 102
w 4
812
IXDEX.
Skull-
fossa of, anterior, 100
middle, 100
posterior, 101
spheno-raaxillary, 106
temporal, 105
zygomatic, 10G
internal surface of, 100
lateral region of, 105
tables of, 35
vertex of, 98
vitreous table of, 35
Socia parotidis, 654
Soft palate, 652
aponeurosis of, 653
arches of, 652
muscles of, 653
pillars of, 652
structure of, 652
Sole of foot, muscles of, first
layer, 350
second layer, 352
third layer, 353
Space, anterior perforated, 519
axillary. See Axilla.
Haversian, 38
intercostal, 116
popliteal, 443
boundaries of. 444
contents of, 444
position of contained parts
in, 444
posterior perforated, 519
Spermatic cord, 740
arteries of, 740
course of, 740
lymphatics of, 740
nerves of, 740
relation of to femoral ring,
771
relations of, in inguinal ca-
nal, 742, 762
veins of, 740
Spermatozoa, 744
Sphenoid bone, 72
articulations of, 76
attachment of muscles to, 76
development of, 76
greater wings of, 74
lesser wings of, 75
processes of Ingrassias of, 75
pterygoid processes of, 75
spinous process of, 74
vaginal processes of, 74
Sphenoidal spongy bones, 76
Sphincter ani, 776
of bladder, 731
of rectum, external, 776
internal, 776
of vagina, 780
Spinal column, 40, 55
Spinal cord, 500, 502
arachnoid of, 501
arrangement of gray and
white matter in, 504
central canal of, 506
ligament of, 502
columns of, 503
dura mater of, 500
filum tcrminale of, 502
fissure of, 503
Spinal cord —
foetal peculiarity of, 506
gray commissure of, 504
matter of, 504, 505
ligamcntum denticulatum of,
502
membranes of, 500
neurilemma of, 502
pia mater of, 502
sections of, 504
structure of, 504
substantia cinerea gelatinosa,
503
white commissure of, 503
matter of, 504
Spinal nerves, 561
arrangement into groups,
561
branches of, anterior, 562
posterior, 562
ganglia of, 562
roots of, anterior, 561
posterior, 561
Spine, 40
See also Process, spinous.
of bone, 35
ethmoidal, 72
of ilium, 150
of ischium, 152
nasal, 65
anterior, 85
posterior, 88
pharyngeal, 59
of pubes, 153
of scapula, 126
Spleen, 684
artery of, 688
capillaries of, 688
fibrous elastic coat of, 685
fissure of. 684
hilus of, 684
lymphatics of, 493, 688
Malpighian corpuscles of, 686
nerves of, 688
proper substance of, 685
relations of, 684
serous coat of, 685
size and weight of, 684
structure of, 685
suspensory ligament of, 684
trabecular of, 685
veins of, 688
Spongy bones, 91
cartilage, 182
portion of urethra, 733
tissue of bone, 34
Squamous portion of temporal
bone, 67
Stapes, 635
annular ligament of, 636
Steno's duct, 654
Sternum, 112
articulations of, 116
attachment of muscles to, 11 6
development of, 114
ligaments of, 202
structure of, 114
Stomach, 663
alteration in position of, 664
alveoli of, 666
cardiac orifice of, 663
Stomach —
cellular coat of, 666
curvatures of, 663
fundus of, 663
gastric follicles of, 666
ligaments of, 664
lymphatics of, 498, 666
mucous glands of, 666
mucous membrane of, 666
muscular coat of, 665
oesophageal orifice of, 663
peptic glands of, 666
pyloric end of, 663
orifice of, 663
pylorus, 665
serous coat of, 6/55
simple follicles of, 667
splenic end of, 663
structure of, 665
submucous coat of, 666
surfaces of, 664
vascular coat of, 666
vessels and nerves of, 666
Striae laterales, 522
longitudinales, 522
Stricture, seat of, in direct in
guinal hernia, 765
in femoral hernia, 774
in oblique hernia, 764
Stroma of ovary, 753
Subarachnoid fluid, 509
septum, 501
space of brain, 509
of cord, 501
Sublingual gland. 655
duct of, 655
vessels and nerves of,
655
Submaxillary gland, 655
duct of, 655
nerves of, 655
vessels of, 655
Subpeduncular lobe of cerebel-
lum, 532
Sub-peritoneal areolar tissue,
660
Substantia cinerea gelatinosa,
505
Sulci of cerebrum, 516
Supcrcilia, 625
Superior maxillary bone. 81
articulations of, 86
attachment of muscles to,
86
development of, 85
Supra-renal capsules, 727
cortical substance of, 728
medullary substance of, 728
nerves of, 728
relations of, 728
structure of, 728
vessels of, 728
Surgical anatomy, 33
of abdominal aorta. 420
anterior tibial, 447
arch of aorta, 364
axilla, 401
axillary artery, 404
base of bladder, 7s:'>
bend of elbow, 1(17
brachial artery, 408
IXDEX.
813
Si.rgical anatomy —
jf common carotid artery,
370
iliac artery, 429
dorsalis pedis, 449
external carotid, 372
iliac, 437
facial artery, 376
femoral artery, 440
hernia, 766
hamstring tendons, 340
innominate artery, 367
inguinal hernia, 758
internal carotid, 386
iliac, 431
ischio-rectal region, 775
laryngo - tracheal region,
713
lingual artery, 374
muscles of eye, 242
lower extremity, 354
soft palate, 266
upper extremity, 320
oesophagus, 657
perineum, 775
popliteal artery, 445
posterior tibial, 450
prostate gland, 782
radial artery, 411
Scarpa's triangle, 438
sterno-mastoid muscle, 256
subclavian artery, 401
superior thyroid, 373
talipes, 348
temporal artery, 379
thoracic aorta, 417
triangles of neck, 382
ulnar artery, 414
Sustentaculum tali, 172
Sutura, 184
dentata, 185
harmonia, 185
iimbosa, 185
notha, 185
serrata, 185
squamosa, 185
vera, 184
Suture, basilar, 97
coronal, 97
cranial. 97
ethmo-sphenoidal, 100
ethmoido-frontal, 100
frontal, 66, 97
fronto-malar, 10.7
-parietal, 97
-sphenoidal, 100
intermaxillary, 85
internasal, 107
interparietal, 97
lambdoid, 97
malo-maxillary, 108
masto-occipital, 98
-parietal. '.17
naso-maxillary, 105
occipito-parietal, 97
petro-occipital. 97
-sphenoidal, 98
sagittal, 97
spheno-parietal, 97
squamo-paiietal. 97
-sphenoidal, 98
Suture —
temporal, 69
transverse. 96
Swallow's nest of cerebellum,
531
Sweat-glands, 007
Symphysis of jaw, 92
pubis, 153
Synarthrosis, 184
Synchondrosis, sacro-iliac, 204
Synovia, 184
Synovial membrane, 183
ankle, 229
articular, 183
astragalo-scaphoid, 232
atlo-axoid, 193
bursal, 184
calcaneo-astragaloid, 230
-cuboid, 231
carpal, 217, 218
carpo-metacarpal, 218
of cartilage of ribs with each
other, 202
chondro-sternal, 200
costo-transverse, 199
-vertebral, 198
elbow, 212
hip, 222
intercostal, 200
interpubic, 206
knee, 226
metacarpal, 218, 219
occipito-atloid, 193
phalanges, 220
radio-ulnar, inferior, 215
superior, 213
sacro-coccvgeal, 205
-iliac, 204
scapulo-clavicular, 210
shoulder, 211
sterno-clavicular, 208
tarsal, 232
tarso-metatarsal, 233
temporo-maxillary, 197
thumb, 197
tibio-fibular, inferior, 227
superior, 227
vaginal, 184
wrist, 216
System, Haversian, 37
portal, 477
Tables of the skull, 35
Tenia hippocampi, 524, 525
semicircularis, 523
violacca, 532
Tarsus, 170
development of, 178
Teeth, 645
bicuspid, 645, 646
body of, 645
canine, 645, 646
of lower jaw, 93
of upper jaw, 82
cement of, 649
chemical composition of, 648,
649
cortical substance of, 649
crown of, ('>!.">
crusta petrosa of, 648
cuspidate, G4G
Teeth-
deciduous, G45
dental tubuli of, 648
dentine of, 648
development of, 649, 650, 651
enamel of, 649
eruption of, G51
eye, 6 !6
false molars, 646
fang of, 645
general characters of, 645
growth of, 651
incisors, 646
iutertubular tissue of, G48
ivory of, 648
large molars, 646
milk, 645, 647
molar, 645, G4G
multicuspidate, 646
permanent, 645. 646
pulp cavity of, 648
roots of, 645
small molars, 646
structure of, 618
temporary, 645, 647
true molars, 64G
wisdom, 647
Temporal bone, 67
articulations of, 72
attachment of muscles to,
72
development of, 71
mastoid portion of, 69
petrous portion of, 69
squamous portion of, 67
structure of, 71
Tendo Achillis, 344
oculi, 242
palpebrarum, 242
Tendon, central, of diaphragm,
291
conjoined, of internal obliqu*
and transversalis, 284,
761
cordiform, of diaphragm, 291
structure of, 237
Tentorium cerebelli, 508
Testicle. See Testis.
Testis, 738
aberrant duct of, 741
coni vasculosi of. 741
coverings of, 739, 740
tunica albuginca, 740
vaginalis, 740
vasculosa, 740
gubernaculum testis, 745
investments of, 740
lobules of, 741
lymphatics of, 492
mode of descent of, 744
pia mater of, 741
' rete of, 741
size and weight of, 739
structure of, 741
tubuli seminiferi of. 71 1
vas deferens of, 742
vasa efferentia of, 741
recta, 741
vasculum aberrans of, 741
vessels and nerves of. 742
Theca vertebralis, 500
814
INDEX.
Thalami optici, 526
Thigh, bone of, 158
fascia of, 327
deep, 328
lata, 328
muscles of back of, 288
of front of, 276
Thorax, 689
base of, 689
bones of, 112
boundaries of, 689
cutaneous nerves of, 577
fasciae of, 294, 298
muscles of, 294
openings of, 689
parts passing through upper
openings of, 689
viscera contained in, 689
Thumb, muscles of, 316
Thymus gland, 722
chemical composition of, 723
lobes of, 722
lymphatics of, 494, 723
reservoir of, 722
structure of, 722
vessels and nerves of, 723
Thyro-hyoid membrane, 705
Thyroid axis, 398
cartilage, 703
gland, 721
chemical composition, 722
isthmus of, 721
lymphatics of, 494, 722
situation of, 721
structure of, 721
vessels and nerves of, 721
Tibia, 165
articulations of, 168
attachment of muscles to, 168
development of, 168
fracture of shaft of, 356
structure of, 168
Tongue, 608
arteries of, 611
cutis of, 609
dorsum, 609
epithelium of, 610
fibrous septum of, 610
follicles of, 610
mucous glands of, 610
membrane of, 609
muscular fibres of, 610
muscles of, 260
nerves of, 611
papilla? of, 609. See Papillae,
tip of, 609
Tonsils, 653
nerves of, 653
vessels of. 653
of the cerebellum, 531, 532
Tooth. Bee Teeth.
Torcular Herophili, 60, 464
Trabecular of corpus cavcrno-
sum, 737
of spleen, 685
of testis, 741
Trachea, 711
cartilages of, 712
glands of, 713
relations of, 712
structure of, 713
Trachea —
surgical anatomy of, 713
vessels and nerves of, 713
Tracheotomy, 713, 714
Tract, optic, 536
Tractus intermedio lateralis,
505
opticus, 536
Tragus, 629
Trapezium bone, 143
Trapezoid bone, 143
Triangle of Hesselbach, 765
inferior carotid, 383
of neck, anterior, 382
posterior, 384
surgical anatomy of, 382
occipital, 384
Scarpa's, 438
subclavian, 384
submaxillary, 383
superior carotid, 383
Tricuspid valves, 694
Trigeminus nerve, 545
Trigone vdsicale, 732
Trigonum vesicae, 732
Triquetral bones, 80
Trochanters, greater and lesser,
159
Trochlea of humerus, 131
Trunk, muscles of, 269
Tube, auditory, 631
Eustachian, 634
Fallopian, 752
Tuber cinereum, 519
ischii, 152
Tubercle of bone, 35
of the clavicle, 121
of the femur, 160
genial, 93
lachrymal, 43, 625
laminated, of cerebellum, 531
of Lower, 693
for odontoid ligaments, 59
of ribs, 117
of scaphoid, 141
of the tibia, 166
of ulna, 135
of zygoma, 68
Tubercula quadrigemina, 529
Tuberculo cinereo, 514
Tuberculum Loweri. 693
Tuberosities of humerus,greater
and lesser, 129
of tibia, 165
Tuberosity of bone, 35
of ischium, 152
maxillary, 82
of palate bone, 89
of radius, 138
Tubes, bronchial, 712
structure of, in lung, 719
Tubuli, dental, 648
of Ferrein, 726
galactophori, 756
lactiferi, 756
recti, 741
seminiferi, 741
uriniferi, 725
Tubulus centralis modioli, 639
Tuft, vascular, in Malpighian
bodies of kidney, 726
Tunica albuginea, 740
of ovary, 753
Ruschiana, 618
vaginalis, 740
propria, 740
reflexa, 740
vasculosa testis, 740
Turbinated bone, inferior, 91
middle, 78
superior, 78
Tutamina oculi, 625
Tympanic bone, 71, 635
Tympanum, 632
arteries of, 636
cavity of, 632 .
membrane of, 634
mucous membrane of, 636
muscles of, 636
nerves of, 637
ossicula of, 634. See Ossicula.
veins of, 637
Ulna, 133
articulations of, 138
development of, 138
fracture of coronoid process
of, 322
of olecranon process, 322
of shaft, 323
muscles attached to, 138
Umbilicus, 287
Unciform bone, 145
Ungual phalanges, 147
Upper extremity, arteries of,
391
articulations of, 207
bones of, 121
fascia of, 293
ligaments of, 207
lymphatics of, 486
muscles of, 293
nerves of, 566
surgical anatomy of, 320
veins of, 466
Urachus, 730
Ureters, 726, 727
muscles of, 731
nerves of, 727
relations of, 727
structure of, 727
vessels of, 727
Urethra, female, relations of, 748
structure of, 748
male, 732
bulbous portion of, 733
caput gallinaginis of, 733
external aperture of. 733
membranous portion of,
733
prostatic portion of, 732
sinus of, 733
rupture of, course taken by
urine in, 778
sinus pocularis of, 733
spongy portion of, 733
structure of, 733
veru montanum of, 732
vesicula prostatica of, 733
Urinary organs, 724
Uterus, 750
appendages of, 752
Uterus —
arbor vita; of, 751
body of, 750
cavity of, 750
cervix of, 750
in foetus, 752
fundus of, 750
ligaments of, 750, 754
lymphatics of, 492, 751
during menstruation, 752
in old age, 752
orifices of, 750
after parturition, 752
during pregnancy, 752
at puberty. 752
shape, position, dimensions,
&c, of, 686
structure of, 751
vessels and nerves of, 751
Uterus masculinus, 733
Utricle of vestibule, 641
Utriculus, 641
Uvea, 619
Uvula, 652, 656
of cerebellum, 531
vesicae, 732
Vagina, 749
columns of, 749
direction of, 749
dimensions of, 749
lymphatics of, 492
orifice of, 747
relations of, 749
shape of, 749
situation of, 749
structure of, 749
Valve or Valves —
of Bauhin, 671
of cystic duct, 682
of gall-bladder, 682
of heart, 693,697
coronary, 693
Eustachian, 693
mitral, 697
of right auricle, 693
semilunar, aortic, 697
pulmonic, 695
tricuspid, 694
ileo-cajcal, 671
of Kerkring, 668
of veins, 457
of Vieussens, 529
Valvula Bauhini, 671
Valvukc conniventes, 668
Vas aberrans, 742
deferens, 742
structure of, 742
Vasa aberrantia of brachial ar-
tery, 407
afferentia of lymphatic
glands, 482
brevia arteries, 422
veins, 477
efferentia of testis, 741
of lymphatic glands, 482
inferentia, 482
intestini tenuis, 424
recta, 741
vasorum of arteries, 360
of veins, 457
INDEX.
Vascular system, changes in,
at birth, 702
peculiarities of, in foetus, 699
Vasculum aberrans, 741
Vein or Veins —
General Anatomy of, 455
anastomoses of, 455
arrangement into groups,
457
coats of, 456
muscular tissue of, 457
plexus of, 455. See Plexus
of veins,
sinuses of, 455
size, form, etc., of, 455
structure of, 457
valves of, 457
vessels and nerves of, 457
Vein or Veins —
Descriptive Anatomy of, 457
of alas nasi, 458
angular, 458
articular, of knee, 474
of jaw, 458
auricular, anterior, 458
posterior, 459
axillary, 468
azygos, 470
left lower, 470
upper, 471
right, 470
basilic, 467
basi-vertebral, 472
of bone, 37
brachial, 468
brachio-cephalic, 468
bronchial, 471, 720
buccal, 458
cardiac, 479
anterior. 479
great, 479
posterior, 479
cava, inferior, 475, 693
superior, 470, 693
cephalic, 467
cerebellar, 463
cerebral, 462
deep, 463
inferior anterior, 463
lateral, 463
median, 463
superficial, 462
superior, 462
cervical, ascending, 461
deep, 461
choroid of brain, 463
circumflex iliac, 474
superficial, 473
comites, 455
of brachial, 468
interosseous, 467
radial, 467
ulnar, 467
condyloid, posterior, 461
coronary, 479
of corpora cavernosa,
738
of corpus spongiosum,
738
striatum, 463, 523
cutaneous, -155
815
Vein or Veins —
cystic, 478
deep, 455
dental, inferior, 459
diaphragmatic, 476
digital of hand, 467
of diploe, 461
dorsal, of penis, 475
dorsalis nasi, 458
pedis, 474
dorsi-spinal, 471
epigastric, 474
superficial, 473
of eyeball, 625
facial, 459
femoral, 474
relation of to femoral arte*
ry, 440
to femoral ring, 771
frontal, 458
of Galen, 463, 523, 526
gastric, 477
gastro-epiploic, left, 477
gluteal, 474
hemorrhoidal, inferior, 475
middle, 475
superior, 475
of head, 457
hepatic, 477, 678
iliac, common, 475
peculiarities of, 475
external, 474
internal, 474
ilio-lumbar, 475
innominate, 468
left, 468
peculiarities of, 469
right, 468
intercostal, superior, 470
left, 470
right, 470
interlobular, 679
interosseous, of forearm, 467
intralobular, 679
jugular, anterior, 460
external, 460
posterior, 460
internal, 460
sinus of, 461
of kidney, 726
labial, inferior, 459
superior, 459
laryngeal, 461
lateral sacral, 475
lingual, 461
of liver, 678
longitudinal, inferior, 464
superior, 463
of lower extremity, 473
lumbar, 476
ascending, 476
mammary, internal, 469
masseteric, 458
mastoid, 430
maxillary, internal, 459
median, 467
basilic, 467
cephalic, 467
cutaneous, 467
medulli-spinal, 471, 472
meningeal, 459
m
81G
INDEX.
Vein or Veins —
meningo-raekidian, 471
mesenteric, inferior, 477
superior, 477
nasal, 458
of neck, 460
oblique, 479
obturator, 474
occipital, 459
oesophageal, 470
ophthalmic, 465
ovarian, 476
palatine, inferior, 458
palmar, deep, 468
palpebral, inferior, 459
superior, 459
pancreatic, 477
pancreatico-duodenal, 477
parotid, 474
peroneal, 459
pharyngeal, 461
phrenic, 476
plantar, external, 474
internal, 474
popliteal, 474
portal, 677, 678, 679
profunda femoris, 474
from pterygoid plexus, 459
pudic, external, 473
internal, 474
pulmonary, 455,479, 696,720
radial, 467
ranine, 459
renal, 476, 726
sacral, lateral, 475
middle, 475
salvatella, 467
saphenous, external or short,
473
internal or long, 473
sciatic, 474
spermatic, 476, 676
sphenopalatine, 461
spinal, 471, 472
anterior longitudinal, 471
posterior longitudinal, 471
splenic, 477
stylo-mastoid, 459
subclavian, 468
sublobular, 679
submaxillary, 459
submental, 459
superficial, 455
supra-orbital, 458
supra-renal, 476, 728
supra-scapular, 460
sural, -174
systemic, 455
temporal, 459
middle, 4.">0
tcmporo-maxillary, 459
Thehesii, 479
of thorax, 466
thyroid, inferior, 469
middle, 461
superior, 461
Vein or Veins —
tibial, anterior, 474
posterior, 474
transverse cervical, 460
facial, 459
ulnar, anterior, 466
deep, 466
posterior, 467
umbilical, 699, 701, 702
how obliterated, 702
of upper extremity and tho-
rax, 466
vaginal, of liver, 680
vasa brevia, 477
ventricular, 463
of vertebra, 461
of bodies of, 472
Vidian, 461
See also Vena and Vena?.
Velum interpositum, 523, 526
arteries and veins of, 526
pendulum palati, 652
Vena cava, inferior, 475
peculiarities of, 476
superior, 470
corporis striati. 463
innominata, 468
porta;, 477, 677, 678
salvatella, 467
See also Vein.
Venaa basis vertebrarum, 471
comites, 455, 474
Galeni. See Veins of Galen.
minima3 cordis, 479
Thebesii, 479
vorticosa?, 618
See also Vein. I
Venter of ilium, 150
of scapula, 123
Ventricle of brain, third, 527
gray matter of, 527
fourth, 532
lining membrane of, 532
fifth, 524
lateral, 522
of corpus callosum, 521
of heart, left, 696
right, 691
of larynx, 707, 708
Vertebra dentata, 43
prominens, 44
Vertebra;, 40
attachment of muscles to, 49
cervical, 41
coccygeal, 50
development of, 48
dorsal, 44
false, 50
general characters of, 40
ligaments of, 188
lumbar, 47
ossification of, 49
peculiar, 42, 45, 47
pedicles of, 41
sacral, 50
structure of, 47
Vertebral column, 40, 55
ossification of, 49
Vertex of skull. 98
Vera montanum, 732
Vesicles, Graafian. See Graa
fian vesicles.
Vesicula prostatica, 733
Vesicuke scminales, form and
size of, 743
nerves of, 744
relations of, 744
1 structure of, 744
vessels of, 744
Vesicular nervous matter, 495,
496
Vestibule of car, 687
acpieduct of, 70, 638
of vulva, 747
Vibrissa; of nose, fill •
Vieussens, valve of, 529
Villi, 669
Viscera, abdominal, position of
in regions. 659
pelvic, position of at outlet of
pelvis, 782
thoracic, 689
Vitelline membrane, 754
Vitreous body, 623
humor of the eye, 623
table of the skull, 35
Vocal cords, false, 707
inferior, 708
superior, 707 ■
true, 708 »
Voice, organs of, 702
Voluntary muscles, 235
Vomer, 92
ala3 of, 92
articulations of, 92
development of, 92
Vortex of heart, 698
Vulva, 747
Wharton's duct, 655
White substance of brain, che-
mical analysis of, 495
of Schwann, 496
Willis, circle of, 397
Winslow, foramen of, 661
Wirsung, canal of, 683
Wisdom tooth, 647
Womb. See Uterus.
Wormian bones, 80
Wrisberg, cartilages of, 705
nerve of, 570
Wrist-joint, 216
Xiphoid appendix, 114
Y-shaped centre of acetabu-
lum, 155
Yelk of ovum, 754
Yellow spot of retina, 620
Zona pellucida, 754
Zygoma, 67
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