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(The Medical Epitome Series )

ANATOMY 370

A MANUAL FOR STUDENTS AND PRACTITIONERS

BY
JOHN FORSYTH LITTLE, M.D.

ASSISTANT DEMONSTRATOR OF ANATOMY, JEFFERSON MEDICAL COLLEGE
PHILADELPHIA

THIRD EDITION, REVISED AND ENLARGED
INCLUDING

ELECTED LIST OF STATE BOARD EXAMINATION
QUESTIONS

ILLUSTRATED WITH SEVENTY-FIVE ENGRAVINGS

| LEA & FEBIGER
PHILADELPHIA AND NEW YORK

in the Office of the Librarian of C

es i

Pat arte:

2

PREFACE

Tuts book is intended to present in a clear and concise
manner more than the mere essentials of human. anatomy.
To accomplish this some of the less important points have
yielded space to those of more practical bearing. Embry-
ology, histology, and’ applied anatomy have not been con-
sidered as coming within its scope.

It is interesting to note the history of this little work. _

~The original issue was published from the manuscript of
Dr. F. J. Brockway, whose untimely death was a great loss
to all true students of anatomy. The value of his work
was so widely appreciated that it ran through several
printings, and in response to the continued demand it was
revised with additions, and rearranged with questions
grouped at the end of the sections, by Dr. Henry E. Hale,
then Demonstrator of Anatomy at the College of Physicians
and Surgeons, New York. His edition was likewise widely
approved, as indicated by the call for successive printings.
oe he became identified with other subjects, and
this new and revised issue is accordingly executed by other
hands. It is hoped that so brought to date the little work
will continue to enjoy its merited popularity. Perhaps
the most important of the changes is that relating to the
cerebrospinal axis, which is described with sufficient detail
of the most important masses entering into its intricate
formation to enable the reader to grasp its structures with
facility. In addition to the questions following each section
a selected list of State Board Examination Questions has
been inserted immediately preceding the index, a feature
which should prove of service to the student preparing
himself in the subject.
_ ] wish to thank my friend and colleague, Poofessor E. A.
Spitzka, of the Jefferson Medical College, for his encour-
agement and valuable suggestions, particularly in regard
to the nerve system,

JFL.

*) i eee ree ST

PREFACE TO SECOND EDITION

Tuts book is intended to present in a clear and concise
manner more than the mere essentials of human anatomy.
To accomplish this some of the less important points have
yielded space to those of more practical bearing. Embry-
ology, histology, and applied anatomy have not been con-
sidered as coming within its scope.

It is interesting to note the history of this little work.
The original issue was published from the manuscript of
Dr. F. J. Brockway, whose untimely death was a great loss
to all true students of anatomy. The value of his work
was so widely appreciated that it ran through several
printings, and in response to the continued demand it was
revised with additions, and rearranged with questions

then Demonstrator of Anatomy at the College of Physicians
and Surgeons, New York. His edition was likewise widely
approved, as indicated by the call for successive printings.
Meanwhile he became identified with other subjects, and
this new and revised issue is accordingly executed by
other hands. It is hoped that so brought to date the little
work will continue to enjoy its merited popularity. Perhaps
the most important of the changes is that relating to the
cerebrospinal axis, which is described with sufficient detail
of the most important masses entering into its intricate
formation to enable the reader to grasp its structure with
facility.

I wish to thank my friend and colleague, Professor
E. A. Spitzka, of the Jefferson Medical College, for his
encouragement and valuable suggestions, particularly in
regard to the nerve system.

: then D at the end of the sections, by Dr. Henry E. Hale,

J. F. L.

PHILADELPHIA, 1911.

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CONTENTS

PART I

OSTEOLOGY, OR THE ANATOMY OF THE OSSEOUS

SYSTEM.

The Classification and Structure of Bones

SPECIAL ANATOMY OF THE SKELETON

The Vertebral Column: The Cervical Vertebrz; The Dorsal
Vertebre; The Lumbar (fi icine The Sacrum and
Coccyx . : :

The Vertebral Column as a Whole .

The Hyoid Bone Bagh

THE BONES OF THE HEAD

The Bones of the Cranium: The Occipital Bone; The Parietal
Bones; The Frontal Bone; The Temporal Bones; The
Sphenoid Bone; The Ethmoid Bone . .

The Bones of the Face: The Superior Maxillary Bones;
The Palate Bone; The Vomer; The Malar Bones; The
Nasal Bones; The Lacrymal Bones; The Inferior Tur-
binated Bones; The Inferior Maxillary Bone hoes)

The Skull as a Whole

THE THORAX

The Thorax as a Whole .
The Sternum .
The Ribs and Costal Cartilages .

17

19-30
30-31
dl

Vi CONTENTS

THE BONES OF THE UPPER EXTREMITY
The Bones of the Shoulder Girdle: The baa The

Scapula . ; ot Pes 78-82
The Bones of the Arm: The Humerus j aes 82-86
The Bones of the Forearm: The Ulna; The Radius 2n.4 86-92
The Bones of the Hand... hetts 92-93

THE BONES OF THE LOWER EXTREMITY

The Bones of the Pelvis (Pelvic Girdle): The Hip Bones
(Ossa Innominata); The Ilium; The Os reas The

Ischium . : 93-98
The Pelvis as a Whole . Ok Bee 98-99
The Bones of the Thigh: The Femur; ‘The Patella. . . 99-103
The Bones of the Leg: ‘The Tibia; The Fibula): > eo =. 103-106

The Bones of the Foot: The Os Calcis; The Astragalus; The
Cuboid; The Seaphoid; The Cuneiform; The Metatarsal

and The Phlanges .. .. 106-111
PART II
ARTHROLOGY, OR THE ANATOMY OF THE
ARTICULATIONS
The General Structure of Joints . ...... , 113
The Classification of Joints. os 3) Po a eee eee

THE ARTICULATIONS OF THE TRUNK AND HEAD

The Articulations of the Vertebral Column: The Ligaments

of the Bodies; The Ligaments of the Laminz; The Lagi

ments of the Processes .. . » 115-118
The Movements of the Spinal Column. 118
The Articulations of the Axis and Atlas: The Articulations

of the Occiput and Atlas; The Ligaments pier stisa:

the Occiput and Axis. 118-121
The Articulations Connecting the Ribs with the Vertebree | . 121-123
The Articulations of the Costal Caeene? with the Sternum . 123
The Intercostal Articulations . . . 123-124
The Articulations of the Sternum ....... . 124

The Temporomaxillary Articulation . . . . . . . 4124-126

CONTENTS Vil

The Articulations of the Vertebral Column with the Pelvis . 126-127
The Articulations of the Pelvis: Between the Sacrum and

Ilium, the Sacrum and Ischium, the Sacrum and Coccyx,

and between the Pubic Bones ... ... .. -...—_...~—s«j—Ss: 127-129

THE ARTICULATIONS OF THE UPPER EXTREMITY

The Shoulder Girdle: The Sternoclavicular Articulation;
The Acromioclavicular Articulation; The det! Liga-

ments of the Scapula . . . .. . ar tr Ak Ae Ok
TUG NHOUMUrHIOINGS le. oe roe 28k re yas 182-185
The Elbow-joint . 135-137

The Superior, Middle, and Inferior Radiotlnar Articulations 138-139

ARTICULATIONS OF THE LOWER EXTREMITY

The Hip-joint: The Knee-joint. . 141-151
The Ligaments between the Bones of the Leg: The Upper
Tibiofibular Articulation; The Interosseous Membrane;

The Inferior Tibiofibular Joint; The Ankle-joint . . 151-153
The Joints of the Foot: The Ligaments of the Tarsus; The
Remaining Ligaments of the Foot thie eR ©. 168-164

| s

PART: [iT
MYOLOGY, OR THE’ ANATOMY OF THE MUSCULAR
SYSTEM
ae LOMIGH UMSOTIOFOl?. Se Leh ee 155
EST Ea CRN Ge Sa a te ev a 155
I nt RR dela tal Na SED lc, 156

THE MUSCLES AND FASCIZ OF THE NECK

The Anterior Neck Muscles: The Hyoid Bone Muscles;

- ‘The Muscles of the Tongue; The Muscles of the e Pharynx;
The Muscles of the Soft Palate . . . . . 156-166
The Posterior and Deep Neck Muscles ... ._ .._ ... 166-168

Vili CONTENTS

THE MUSCLES OF THE HEAD

The Epicranial Muscles ._.

The Muscles of the Eyelids and Eyebrows
The Muscles of the Face :

- The Muscles of the Orbit

The Muscles of Mastication .

169-170
170-171
171
171-173 -
173-175

THE MUSCLES AND FASCL# OF THE TRUNK

The Muscles of the Neck and Back: I. The Superficial
Muscles: The Dorsal and Lumbar Fascie. II. The
Deep Longitudinal Muséles ._ .

The Fascize and Muscles of the Abdomen: I. The Vertical
Muscles of the Abdomen. Il. The Transverse Muscles a
the Abdomen .

The Lining Fasciz of the Abdomen

The Fasciz of the Perineum

The Fascie of the Pelvis :

The Muscles of the Perineum in the “Male:
Muscles. Il. The Genito-urinary Muscles

The Muscles of the Perineum in the Female .

The Diaphragm .

Muscles and Fascie of the Thoracic Region: ’ Anterior and

Lateral Thoracic Muscles . Oe ean F

ie, The Anal

MUSCLES AND FASCIZ OF THE THORAX

The Intercostal Muscles:

The Infracostals; The Triangu-
laris Sterni Ute F Waeet a Nees, ar tel ake ;

175-184

184-188
188-189
189-190
190-191

191-193
193-194
194-195

195-198

198-199

MUSCLES AND FASCLZ OF THE UPPER EXTREMITY

The Shoulder and Arm: Acromial Region; Posterior
Scapular Muscles; Anterior Scapular Muscles.

The Upper Arm: The Muscles of the Anterior Surface; ?
Posterior Muscles of the Arm ._.

The Forearm: The Anterior Radioulnar “Region; The
Radial Region .

The Hand: The Muscles of the Dorsal Surface; Radial
Region; Ulnar Region and Middle Palmar Region

200-201
202-204
204-213
213-218

MUSCLES AND FASCLH OF THE LOWER EXTREMITY

Fascia of the Thigh
The Iliac Region .

218-220
220-221

re ee
-

wes

The Muscles and Fascie of the Foot:

oe ~ CONTENTS

The Gluteal Region Sey Le EAN I MR oe gE ee ae RS

The Thigh Muscles: . Anterior Femoral Region; Posterior
Femoral Region; Internal Femoral Region ..

The Muscles and Fascie of the Leg: The Anterior Tibio-
fibular Region; The Fibular or Peroneal Region; The
Posterior Tibiofibular Region; The Deep Muscles .

The Dorsal ie ok
The Plantar Region; The Interossei Muscles. ,

PART IV

221-224
224-230

230-235
235-240

ANGEIOLOGY, OR THE ANATOMY OF THE CIRCU-

LATORY AND LYMPHATIC SYSTEMS

The Pericardium .
The Heart...
The Right Auricle
The Right Ventricle
The Left Auricle .
The Left Ventricle

THE ARTERIES

The Pulmonary Arterial System.

The Corporeal Arterial System: The Aorta .

The Arteries of the Upper Extremity: The Axilla: The
Axillary Artery; The Brachial Artery; The Radial
Artery; The Ulnar Artery; The Thoracic Aorta; The
Abdominal Aorta; The Iliac Arteries ..

The Arteries of the Lower Extremity: The F emoral Artery;
The Popliteal Space; The Popliteal Artery ;

THE VEINS

The Pulmonary Veins

The Systemic Veins:
nate Veins.

The Veins of the Head and Neck

The Veins of the Upper Extremity . :

The Veins of the Trunk: The Inferior Vena Cava .

The Veins of the Lower Extremity . es

The Veins of the Pelvis .

The Portal System

The Thoracic Duct

The Superior Vena Cava and Innomi-

241
241-242
242-243
243-245

245

246

246-247
247-262

262-277
277-282

283

283-285
285-290
290-291
291-292
293
294
295-296
296

X CONTENTS

The Lymphatic Vessels and Nodes of the Lower Extremity 298
The Lymphatic Vessels and Nodes of the Pelvis and Abdo-
men. . + -.. 298-300
The Lymphatic ‘System of the Thorax. . «=... & 300
The Lymphatics of the Upper Limb Sty Hag kary Mee 301
The Absorbent System of the Head and Notk so: dex 301
PART V

NEUROLOGY, OR THE ANATOMY OF THE NERVE
SYSTEM

THE CEREBROSPINAL AXIS

The Spinal Cord . 303-306
The Brain: The Medulla Oblongata; The Pons Varolii; The
Cerebrum; The Base of the Brain; Horizontal Section of
the Brain; The Lateral Ventricles; The Third Ventricle; .
The Cerebellum; The Fourth Ventricle tattle 306-334

THE PERIPHERAL NERVE SYSTEM

The Cranial Nerves: The Olfactory Nerves; The Optic

Nerves; The Motor Oculi; The Pathetic; The Fifth

Nerve; The Sixth Nerve; The Cavernous Sinus; The

Sphenoidal Fissure; The Seventh Nerve; The Auditory

Nerve; The Ninth Nerve; The Pneumogastric Nerve;

The Eleventh Pair; The Hypoglossal . 334-354
The Spinal Nerves: The Cervical Nerves; ; The Cervical

Plexus; The Brachial Plexus; The Dorsal Nerves; The

Lumbar Nerves; The Lumbar Plexus; The Sacral and

_ Coceygeal Nerves; The Sacral Plexus oie ech. 4

THE SYMPATHETIC NERVE SYSTEM

The Sympathetic Nerves of the Neck . . . . . .. . 3874-876
The Sympathetic Nerves of the Thorax . . . . . . 3876-877
The Sympathetic Nerves of the Lumbar Region... . 377
The Sympathetic Nerves of the Sacral eee abe oe tiie 377

The Sympathetic Plexuses .. ToS, Sea

CONTENTS xi

THE ORGANS OF SPECIAL SENSE

Se ee ete eee LY 1 3806886
7 Oe ee ere se ee Oe tr ee ( 38T-396
iG eee ere a roped Se ee 896-397
PART VI
SPLANCHNOLOGY, OR THE ANATOMY OF THE
VISCERA
THE ORGANS OF RESPIRATION
TRG Mare ene a he Ch ee 8 Soe ea 899-406
The Trachea .. A eae EOE RR Ie RS ES oe 406
The Pleure and Mediastinum ......... 406-408
pee remem a UE es to | £08411
The Bronchi Tag Sg aes uri et) AOS SE nae ee: 3 1s Fes 2 be

THE ORGANS OF DIGESTION

eat NONIMIA ots oe ee eg 412
ieee a a eS a es DY 4S)
Gn EM a a Oye ei IG
The Palate Nien ore en Dos au Me ra PSS |) a i a
The Tonsils . ree teaken Erni me ae kata yA aw ed 417
The Salivary a erate oe i ke ee Cae AG
te eee ere A ty ee oe AIO 4
che A aed ee oe eee em on 7 ba 7)
The Peritoneum . . 422-427
The Stomach: The Duodenum; “The Jejunum and Ileum . 427-432
The Large Intestine .. ..—_.. . . « 432-437
a EMEC es re SE ee SAS T—440
me A Oo oe -44t
wD ST ce rae oa ean ier cerame mn amey: 7 3 bon ©: 3

THE URINARY ORGANS

Ea IO ar eo) ich oe Ne ER a Aad a7
i Ne ag SSIES BIG ce ihn ete Ee eS ed ee eae ly gow Le)
Dee ee ee ee i os 445]

xii CONTENTS

THE ORGANS OF REPRODUCTION

Male: The Prostate Gland; The Penis; The Urethra; The
Scrotum; The ‘Testicle and Epididymis .

_ Female: The Vulva; The Urethra; The Vagina; The Uterus; ;

The Fallopian Tubes; The Ovaries; The Parovarium;

The Mammary Glands . be ed

THE DUCTLESS GLANDS

The Thyroid

Parathyroids

Thymus

Spleen .

Suprarenals, Carotid, and Coccygeal

451-459

459-466

466-467
467
467
468
468-469

Pee NA OM Y

PART. I

OSTEOLOGY, OR THE ANATOMY OF THE
OSSEOUS SYSTEM

THE CLASSIFICATION AND STRUCTURE OF BONES

Anatomical Position.—The skeleton is the solid framework
of the body, composed of bones with the intervals completed
by cartilage. The number of bones in the human adult skeleton
is 206, thus classified:

Vertebral column . . 26
, PCE ene on ek ee oe
Axial skeleton .. yahoo cee 1
Ribs and sternum . . 25
— 74
yUpper limbs oa oS, OF
Appendicular skeleton Piewes Luba) ssa 268
— 126
PE eRe a sa 6
EE SEI ae ne notes aaa al 206

The patella and pisiform are included, but not the small sesa-
moid bones. The teeth belong to the epidermal layer.
| 2

18 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

Bones are formed by ossification in two ways—intracartilagi-
nous and intramembranous.

The vertex of the skull—. e., the parietals, the frontal, the
tabular part of the occipital, the squamous, and tympanic
parts of the temporal, the inner plate of the pterygoid process,
the bones of the face except the inferior turbinate and part
of the lower jaw—are formed in membrane. The base of the
skull and all other bones are formed in cartilage. A deposit
of bone begins at one spot, the primary centre; the shaft, or
diaphysis, is formed from this: Most bones have secondary
_or tertiary centres of ossification, and parts derived from them
are the epiphyses (growths wpon). The growth of bone in
length depends upon the cartilage between the epiphyses and
diaphysis; this cartilage acts as a buffer. Growth in circum-
ference is subperiosteal.

All bones are covered with a vascular, connective-tissue
membrane, called periosteum.

For the sake of description, bones are divided into four
classes: (1) Long, (2) short, (3) flat, and (4) irregular bones.

Long bones present a shaft and two extremities. The
shaft is hollow and more or less cylindrical. The walls are
made of dense bone, thickest near the middle, and decreasing
in thickness toward the ends. The hollow in the centre is
the medullary canal, and is lined with internal periosteum or
medullary membrane, and contains marrow in the recent state,
The extremities are expanded portions, made up of spongy
bone, closed in by a thin layer of compact bone. The inter-
stices of the spongy bone also contain marrow. Examples,
femora and humeri.

Short bones are small, made up of spongy bone, with a
compact bony shell. Examples, carpals and tarsals.

Flat bones have two compact plates enclosing a spongy
layer, the diploé.

Irregular bones are such as cannot be classed with either
of the other groups. They are mostly situated symmetrically
across the median plane of the body. Their composition is
a compact shell enclosing spongy bone, which makes up the
great bulk of these bones. Examples, vertebra, sphenoids,
malars, ete.

Medullary Arteries—The medullary aibehics of the large,
long bones of the extremities run from the knee and toward

THE VERTEBRAL COLUMN — 19.

the elbow. ‘This may be remembered by flexing the knees and
elbows, and noting that the medullary arteries run down as
though impelled by gravity.

THE BONES OF THE TRUNK _

The parts of the trunk are the vertebral column, the ster-
num and ribs, the hyoid, and bones of the skull.

The clavicle and scapula do not belong to the trunk; they
form the shoulder girdle.

The os innominatum goes to form the pelvic girdle, com-
pleted behind by the sacrum, which belongs to the trunk.

THE VERTEBRAL COLUMN

The vertebral column is composed of a series of vertebre
(verto, to turn), originally thirty-three in number. The upper
twenty-four remain separate as movable or true vertebre;
these are succeeded by five united into the sacrum; then follow
four dwindled segments united into the coccyx. These lower
nine are the fixed or false vertebre.

Beginning at the skull, there are seven cervical, twelve
dorsal or thoracic connected with ribs, five abdominal or
lumbar, five sacral, and four coccygeal vertebree. The number
in the cervical region is constant; those between the dorsal
and lumbar may vary reciprocally. If there are but eleven
pairs of ribs, the twelfth dorsal vertebra will have lumbar
characteristics; if thirteen pairs, the first lumbar will have
dorsal characteristics. A transitional lumbosacral vertebra
is met with, one side connected with the sacrum, the other
having a free transverse process.

Characteristics of Vertebree.—The first two cervical verte-
bree are called rotation vertebre; all the other true ones, flexion
vertebree. A representative vertebra, like the tenth dorsal,
presents a body for the purpose of support, an arch and spinal
foramen for protection, and seven processes for leverage. The
body or centrum is a short cylinder; the superior and inferior
surfaces are flat, with a rim around the circumference. The
front and sides are convex horizontally and concave from

*

20 OSTEOLOGY, OR ANATOMY OF OSSEOQUS SYSTEM

above down. The posterior surface is slightly concave from
side to side, and marked by one or two venous foramina. The
neural arch consists of two symmetrical portions meeting In
the median plane behind. The anterior part or pedicle rises
from a point on the body where the lateral and posterior -sur-
faces meet; the posterior part or lamina is broad and flat.
The upper and lower borders of pedicles form vertebral notches,
becoming intervertebral foramina between contiguous vertebre.
The spinous process projects back from the junction of the
two laminz. The transverse processes, one.on either side, pro-
ject outward from the arch at the junction of the pedicle
with the lamina. The articular processes, two superior, and
two inferior, project upward and downward at the point of
origin of the transverse processes.

The foramen is bounded anteriorly by the waite: posteriorly
and laterally by the arch; the series of rings thus formed con-
stitutes the spinal canal.

The Cervical Vertebre

The body is smaller than those of any other region; it is
broad transversely; the upper surface is concave because of
the upward projection of lateral lips, and is sloped down in
the front. The under surface is rounded at the sides and lipped
anteriorly, so there is interlocking at the sides to prevent
lateral displacement—an anterior lip to prevent posterior,
and articular processes to prevent anterior, dislocations. The
lamine are long and flat, overlapping those of the vertebra
next below. The superior and inferior notches are nearly equal
indepth. The spinous processes are short and bifid, increasing in
length from the fourth to the seventh inclusive. The transverse
processes are directed outward, downward, and forward, and
present at their extremities an anterior and a posterior tubercle.
Each process is grooved above, and perforated vertically at
its base by the vertebrarterial foramen for a vein, artery, and
plexus of nerves. This foramen is between the two roots of
the process, the posterior corresponding to a dorsal transverse
process, and the anterior to a rib. It is characteristic of this
region. The articular processes are placed at the extremities
of a short vertical column of bone; the superior articular sur-
face is oval and looks up and back; the imferior down and

THE ROTATION VERTEBRA 2]

forward. The foramen is triangular, and larger than in any
other region. The peculiar cervical vertebre are the first, second,
and seventh.

Fic. 1

Anterior
tubercle of trans-
verse process.

Foramen for vertebral
artery. €&

Posterior tubercle of >
transverse process.

Transverse
=) process.

Superior
articular
ATs process.
Inferior
‘articular
process.

Spinous Y’
RJ process. %&

A cervical vertebra. (Gray.)

The Rotation Vertebrz

THe ATLAS

The atlas (supporting globe of head) has no body or spinous
process, but is a large ring with articular and transverse pro-
cesses. The posterior part of the ring corresponds to the
neural canal of the other vertebree; the anterior part is occupied
by the odontoid process of the axis: .The anterior boundary
of the ring is the anterior arch, with a small tubercle in front
for the longus colli muscle. Behind the tubercle is an articular
surface for the odontoid process. At the sides of the ring are
the lateral masses bearing the superior and inferior articular
processes. All the articular processes of the atlas and the
superior ones of the axis are in front of the vertebral notches.
The superior articular surfaces of the atlas are oval and con-
verge infront. ‘They look upward and inward and a little back-
ward, and form a cup for the occipital condyles. These may be
partially subdivided by a transverse groove, and below the inner

22 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

margin of each is a tubercle for the transverse ligament. The
inferior articular surfaces are slightly convex, nearly circular, and
do not wholly cover or fit the superior processes of the axis. The
postervor arch presents in the median line either a ridge, hollow,
or small tubercle. If a spinous process were well developed
here, nodding of the head would be prevented. Just behind
the lateral mass is a smooth sinus, the vertebral notch. The
transverse processes are not bifid—are large and strong for
attachment of rotatory muscles.

Varieties—The posterior or anterior bony arch may be
_ Incomplete; the anterior root of the transverse process may
be ligamentous. A spicule of bone may bridge over the superior
vertebral notch, and the canal formed be subdivided by other
spicules. The artery and vein go through the upper subdivision,
the suboccipital nerve through the lower.

THe Axis (EpIsTROPHEUS)

The second vertebra forms an axis upon which the atlas
carrying the head rotates. The body of the atlas is joined
upon that of the axis in the form of a tooth-like process, the
odontoid. Its apex is pointed, and just below is an enlarge-
ment or head, both giving attachment to bands of the check
ligament.

The process has in front a smooth articular surface for the
arch of the atlas, and behind a smooth groove for the transverse
ligament. This makes a slight constriction, but hardly a
neck.

The anterior surface of the body presents a slight ridge
separating two depressions. The superior articular surface
lies close to the odontoid process, upon the body in part and
upon the pedicles; they look up and out. The inferior articular
surfaces are behind the upper, and resemble corresponding
ones in the cervical region. The spinous process is grooved
inferiorly—is very large and bifid, in contradistinction to that
of the atlas. The transverse processes are short, with the
anterior tubercle nearly suppressed. The inferior vertebral
notch is in front of the articular surface, which is the rule
for both notches below this in the column.

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a a a al

THE ROTATION VERTEBRA 23

THe SEVENTH CERVICAL VERTEBRA (VERTEBRA PROMINENS)

This has a long spinous process, non-bifureated, nearly
horizontal, and projecting under the skin; hence the name
vertebra prominens. Attached to it is the lower end of the
ligamentum nuche. The transverse processes are massive,
slightly grooved, with a small foramen or none at all; the
posterior tubercle is large and the anterior one very small.

Spinal
foramen.

Seventh cervical vertebra, or vertebra prominens.

The vertebral artery and vein do not pass through these for-
amina, but in front of them; both veins may, sometimes the
left artery does; the vessels may enter no foramina until the
fourth vertebra is reached.

Varveties—The anterior tubercle of the sixth is large, and
is called Chassaignac’s and carotid tubercle. The common
carotid artery may be compressed against it; opposite this
level the omohyoid crosses beneath the sternomastoid muscle ,

24 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

the inferior thyroid artery crosses beneath the common carotid.
Opposite it, also, are the cricoid cartilage, the lower ends of
the larynx and pharynx, and the beginning of the trachea
and esophagus.

The Dorsal or Thoracic Vertebree
The dorsal vertebree are intermediate in size between the
cervical and lumbar, increasing in size from above downward.

They are easily recognized by the articular facets for the ribs.

Fia. 3

en Me
Superior articular process.___| KX

Facet for tubercle of rib.

rin > Ip
f lf

"| Demi-facet for head of rib.

Inferior articular process.

/ yy,

A dorsal vertebra.

The body is relatively small, and heart-shaped; its antero-
posterior and transverse diameters are nearly equal, and its
depth is greater behind than in front. Where the arch joins
the body there are articular surfaces for the heads of ribs,
generally two on each side, one at the upper and one at the

THE ATYPICAL DORSAL VERTEBRA 25

lower border; these, when the vertebre are articulated, form
with the facet on the intervertebral fibrocartilage a complete
facet for the head of a rib.

Between the neck of a rib and the transverse process articu-
lating with it is the costotransverse foramen. In the cervical
region this is represented by the vertebral foramen, and in
the lumbar region the space is filled by the bony mass of the
transverse process.

The lamine are broad and flat, and overlap each other.
The spinal foramen is circular and smaller than in other regions.
~The pedicles are directed backward from the upper part of the
body. The inferior intervertebral notches are deeper than in
any other region of the spine.

The superior vertebral notches are shallow or absent.

The spinous processes are bayonet-shaped, and terminate
in a slight tubercle. They are longest and most oblique, sloping
downward and back progressively, from the fifth to the eighth.

The transverse processes are situated behind the articular
processes and pedicles, and are directed outward and backward,
and terminate in a clubbed extremity, which presents anteriorly
a small concave articular surface, for the tuberosity of a rib,
and also three indistinct tubercles, one from the upper border,
one from the lower, and the third externally, for muscular
attachments. The articular processes are nearly vertical, with
smooth flat surfaces. The swperior look back, a little outward
and up. The inferior look in the reverse direction.

The Atypical Dorsal Vertebrez

The first, ninth, tenth, eleventh, and twelfth are to be
distinguished. The first dorsal resembles the seventh cervical.
Its body above is transversely concave and lipped. The
superior vertebral notches are deep, the superior articular
processes are oblique, and the spinous process is nearly hori-
zontal. On the side of the body, close to the upper border,
are a whole facet for the first rib and a very small demifacet
below for the second rib.

The twelve ribs correspond to twelve joint surfaces, but
these are divided, so that only the first, tenth, eleventh, and
twelfth present single facets; the first in addition has a half- |
facet, and the ninth has one demifacet above and none below.

26 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

In some cases the ninth vertebra has two demifacets on each
side; in these instances the tenth has a demifacet above and
none below.

The tenth dorsal touches only one rib on a side, and has
a complete facet, mostly on the pedicle at its upper border.
The transverse process has a small facet.

The eleventh dorsal has one complete facet on each side,
but none on the transverse process.

The twelfth dorsal has a single facet on each side. It strongly
resembles a lumbar vertebra.

The inferior articular surfaces turn out. ‘The spinous pro-
cess is short and nearly horizontal.

The transverse processes are short, and present near their
extremities the external, superior, and inferior tubercles, which
correspond respectively to the transverse, mammallary, and
accessory processes of the lumbar vertebre. Rudiments of
these tubercles may be sometimes seen on the other dorsal
vertebre. The row of costal facets forms the anterior border
of the intervertebral foramina. The ribs in moving intrude
somewhat upon the vessels and nerves in those foramina;
hence the “ floating,’’ most movable, ribs articulate with single
vertebre. ;

The Lumbar Vertebree

These are the largest of the movable vertebre. They may
be distinguished by the absence of costal articular surfaces
and the absence of foramina through the transverse processes.
The body is reniform, broad transversely, deeper in front
than behind, and markedly constricted at the sides. The
pedicles are very thick, directed backward from the upper
part of the bodies. The lamina are short and thick, the superior
notches shallow. The spinous. processes are horizontal, and
broad and thickened at their extremities. The spinal foramen
is triangular, larger than in the dorsal region, but smaller
than that in the cervical.

The transverse processes are slender and project directly
out; they are in front of the articular processes, and are con-
sidered to be homologous with the ribs. Their extremities
lie in series with the external tubercles of the lower dorsal
transverse processes. The accessory process (anapophysis)
lies behind each lumbar transverse process at its base, and

THE LUMBAR VERTEBRA 27

points down. It is large in some animals, and locks the verte-
bree together.

The articular processes present vertical peticata? surfaces,
the superior concave looking in and back, the superior are
farther apart than the inferior, and embrace an inferior pair
above them. The inferior are convex and look outward and

forward.
Fra. 4

Inf. articular process.

Mammillary process.
Costal process. YP

Accessory process.

A lumbar vertebra. (Gray.)

The mammillary process (metapophysis) projects back from
each superior articular process.

The fifth lumbar is massive, the inferior articular processes
wider apart than the upper; the transverse processes are broad
and conical, and the lamine project into the spinal forainen.

28 OSTEOLOGY,OR ANATOMY OF OSSEOUS SYSTEM

The Sacrum and the Coccyx

The sacrum and the coccyx are the result of the fusing of
the lower nine vertebrze into two bones, five to make up the
sacrum, and four (occasionally five) the coccyx.

The sacrum is pyramidal, much larger than the coceyx;
situated between the iliac bones, articulating above with the
fifth lumbar vertebra, below with the coeeyx. It is much
curved on itself, with the concavity in front. It presents
an anterior or ventral and a posterior or dorsal surface, two
lateral masses, a base, an apex, and a central canal for deserip-
tion.

The anterior or ventral surface looks considerably downward,
forming a projection with the last lumbar, the sacrovertebral
angle (about 120 degrees). This surface is concave from above
down and less so from side to side, and is crossed by four hori-
zontal ridges, indicating the union of five vertebre. At the
ends of the ridges are four anterior sacral foramina, which
lead externally into grooves on the lateral masses.

The two rows of foramina are approximately vertical, only
approaching the median line slightly below, as the widths
of the bodies are equal. They are directed forward and slightly
outward, and diminish in size from above downward. The
anterior branches of the sacral nerves pass through them.

The posterior or dorsal surface looks up and back, is convex
and rough, and along the median line are three or four small
spinous processes, more or less connected, forming a ridge;
the upper is prominent and usually quite distinct from the
others. Below the ridge is an inverted V- or U-shaped open-
ing into the central canal. It is bounded. by the imperfect
lamin of the fourth and fifth sacral, and by the inferior articu-
lar processes of the last sacral, which are prolonged down into
the sacral cornua to meet corresponding ones from the coccyx.
On each side of the median ridge the united lamine are hollowed
into the sacral groove, a continuation of the vertebral groove
above, giving origin to a part of the erector spine; next exter-
nally is a row of tubercles representing articular and mammillary
processes; next the four posterior sacral foramina, opposite
to, but smaller than, the anterior. They transmit the posterior —
branches of the sacral nerves and correspond to the spaces

THE SACRUM AND THE COCCYX 29

between the transverse processes—the anterior to the spaces
between two ribs.

The lateral mass is that part external to the foramina, broad
above and narrow below. It is made up of broadened trans-
verse processes, rudiments of which are seen outside the posterior
sacral foramina; the first pair are large, the second are smaller,
on each side these two and the upper half of the third, by an
uneven auricular lateral surface, enter into the formation of
the sacroiliac joint; the fourth and fifth give attachment to
portions of the gluteus maximus, and the greater and lesser
sacrosciatic ligaments. Anteriorly are four shallow grooves,
separated by ridges which give attachment to the pyriformis
muscle. Behind the auricular surface it is very rough for
the attachment of the posterior sacroiliac ligament. Lower
down the bone terminates in the inferior lateral angle, below
which is a half-notch, forming a foramen with the coccyx for
the fifth sacral nerve.

The base shows the reniform first sacral body, behind which
is the triangular aperture of the sacral canal; on each side of
this is a large articular process similar to the superior ones
of the lumbar vertebra, bearing a large mammillary process.
In front of this is a vertebral groove which helps form the
last lumbar intervertebral foramen. Externally is a modified
transverse process, and in front of that a smooth triangular
- surface continuous with the iliac fossa, the ala of the sacrum.

The apex is the body of the fifth sacral vertebra, transversely
oval; it articulates with the coccyx. The sacral canal curves
with the bone, and becomes smaller as it descends. A trans-
verse section is triangular above, but flattened below, its
posterior wall, however, being still arched. From it there
pass out four pairs of intervertebral foramina, opening anteriorly
and posteriorly into the anterior and posterior sacral foramina,
and closed externally by the lateral masses.

Differences in the Sacrum of the Male and Female.—In
the female it is wider, is less curved, the upper half nearly
straight, is more obliquely placed, and forms a more marked
promontory than in the male.

The coccyx is pyramidal. Its vertebrie are very rudimentary i
four in number (rarely five or three). Of the first one, the
pedicles and superior articular cornua project upward, and
help form the last intervertebral foramen, The short trans-

- 30 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

verse process usually bounds a notch for the anterior division
of the fifth sacral nerve; or if it touches the inferior lateral
angle of the sacrum, it forms a fifth anterior sacral foramen.
The second vertebra has rudiments of transverse processes,
and two small eminences in line with the cornua, representing
the last traces of a neural arch. The third and fourth are
mere nodules, and represent vertebral bodies only. In adult
life the first piece is often separate, and the other three united.
All four may form one bone, which occurs oftener and earlier
in the male.

To the edges of the coccyx are attached, an front, the coccy-
geus muscle; behind, the gluteus maximus; and between these
the sacrosciatic ligaments. To the apex is attached the external
anal sphincter.

This bone may consist of five vertebrae, or more rarely of
only three.

The Vertebral Column as a Whole

It is a central axis upon which other parts are arranged,
situated in the median line at the posterior part of the trunk;
above, it supports the head, laterally the ribs, and it rests
on the hip bones below. Its average length measured along
the curves is 28 inches in the male and 27 inches in the female;
persons seated in a row appear of about the same height.

Viewed from the front, the column is formed of two pyra-
mids applied base to base at the junction of the last lumbar
with the sacrum.

All three diameters of the vertebre increase from the third
cervical to the last lumbar; vertical diameter, from 2 to 14
inches (14 mm. to 29 mm.); sagittal, from 2 to 12 fates (14
mm. to 35 mm.); transverse (does not increase in dorsal region),
from 4 to 24 inches (21 mm. to 55 mm.).

.The column presents a slight lateral curve, convex to the
right in right-handed persons, convex to the left in left-handed
persons: (Bichat).

Viewed laterally there are four curves, alternately convex
and concave; the cervical, dorsal, lumbar, and pelvic; the
cervical extends from the odontoid to the second dorsal; the
dorsal is concave forward and ends at the twelfth dorsal; the
lumbar ends at the sacrovertebral angle, and the pelvic ends
at the tip of the coccyx. The dorsal and pelvic curves are

?

a= so foc See Sak RB ts Fe ye” Ge nT pS
: : .

THE HYOID BONE jl

primary, exist at birth, enter into the formation of bone-
walled cavities, and are due to the conformation of the vertebral
bodies. The cervical and lumbar curves are secondary, and
are formed after birth. They are mainly due to a change in
shape of the intervertebral disks.

Posteriorly, the spines occupy the median line or may be
normally twisted a little from it. . In the cervical region they
are short and bifid, sloping backward and a little downward;
in the dorsal they are oblique above, more oblique in the mid-
portion, and nearly horizontal below; in the lumbar they are
horizontal. A cross-section of a cervical spine is semilunar;
of a dorsal, triangular; of a lumbar, oblong. On either side
of the spines is the vertebral groove, bounded externally in
the cervical and dorsal region by the transverse processes, and
in the lumbar by the mammillary processes. The transverse
processes of the atlas are long; of the axis, short, increasing
to the first dorsal, thence diminishing to the last dorsal, and
becoming suddenly much longer in the lumbar vertebre.
In the cervical region the transverse processes are in front
of the articular processes and between the intervertebral
foramina. In the dorsal region they are behind both. In
the lumbar region they are in front of the articular processes
and behind the intervertebral foramina.

The intervertebral foramina are always in front of the articular
processes, except those of the atlas and the upper ones of the
axis. They are named from the upper of the two vertebree
which go to form them, excepting in the cervical region, where
there are eight, the fissure between the skull and atlas being
called the first. |

The spinal canal has three sets of openings into it, the two
rows of the intervertebral foramina and the intervertebral
fissures between the lamina. It is narrowest in those parts
having least motion, viz., in the dorsal and sacral regions.
It is round and 2 of an inch (17 mm.) in diameter in the dorsal
region; it is triangular, with the apex behind, in the cervical
and lumbar regions; and largest of all in the cervical regions.

The Hyoid Bone

The hyoid, or os lingue, is situated at the base of the tongue
opposite the second or third cervical vertebra, and is shaped
like the Greek letter wpsilon.

32 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

It is made up of five portions, a body, two greater and two
lesser cornua.

The body is prismatic, presenting three roughly quadrilateral
surfaces and five borders. It is compressed obliquely from —
above downward and backward.

The superior surface looks upward and a little forward, and
is separated by a horizontal border or ridge, with a tubercle
in the centre, from the anterior surface. There are depressions
above and below this border, on either side of the median line,
for muscular attachment of the geniohyoid over the greater
part of the anterior surface and adjoining part of the superior.
On the superior surface behind this is the geniohyoglossus and
chondroglossus. On the anterior surface from within out, the
mylohyoid, stylohyoid, and aponeurosis of the digastric, and
between two angular processes of the geniohyoid externally, a
part of the hyoglossus.

The posterior surface is concave and faces the epiglottis,
from which it is separated by loose areolar tissue and the
thyrohyoid membrane.

The borders are anterior, posterior, and inferior.

The anterior border is rounded and separates the anterior and
superior surfaces. The attachment of the geniohyoid extends
over much of it.

The posterior border is well marked and gives attachment
to the thyrohyoid membrane.

The inferior border has attached in front the sternohyoid,
and laterally the omohyoid and a part of the thyrohyoid.

The lateral borders are small and oval for articulation with
the greater cornua.

The great cornua project backward, and are flattened obliquely
from above downward, terminating posteriorly in a tubercle
for attachment of the lateral thyrohyoid ligament.

The anteroexternal surface has attached a portion of the
hyoglossus, and to the upper border the middle constrictor
of the pharynx, and their lower borders a portion of the thyro-
hyoid muscle. After middle life they have bony union with
the body.

The small cornua are short and conical, and project up and
back from the junctions of the great cornua and body; they
give attachment to the stylohyoid ligaments and have synovial
articulations with the body.

bf

THE OCCIPITAL BONE 00

THE BONES OF THE HEAD

The skull is divided into two parts, the cranium and face;
the former protects the brain; the face surrounds the mouth,
nasal cavities, and orbits in part. There are twenty-two bones
forming the skull as a whole.

The cranium has eight bones.

(a) Unpaired: (b) Paired: .
Occipital. Temporal.
Sphenoid. Parietal.
Ethmoid.

Frontal.
The face has fourteen bones.

(a) Unpaired: (b) Paired:
Vomer. Nasals.
Mandible. Maxille.

Lacrymals.
Malars.
Palates.
Turbinates.

THE BONES OF THE CRANIUM

The Occipital Bone

The occipital bone, situated in the back part and base of
the skull, is flattened, lozenge-shaped, and bent on itself,
presenting two surfaces, four borders, and four angles. The
internal or cerebral surface is concave; the posterior or external
is convex. It articulates with six bones—two parietal, two
temporal, the sphenoid, and atlas.

Below and in front the bone is pierced by the foramen mag-
num, a large oval opening with its long axis anteroposteriorly
placed (foramen occipitale), for the passage of the spinal cord
and membranes, spinal portions of the spinal accessory nerves,
and two vertebral arteries. The part behind the foramen is
the tabular portion, in front is the basilar portion, at the sides
are the condylar portions.

The tabular portion presents posteriorly near the centre

3 ‘

34 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

the eaternal occipital protuberance, from which the superior
curved line arches outward on each side to the lateral angles;
a little above this may usually be seen the highest or swpreme
curved line. Below the protuberance is a median eaternal
occipital crest, from the centre of which passes out the inferior
curved line to the jugular processes.

FORAMEN
MAGNUM

UGULAR PROCESS

ARROW IN ANTERIOR
CONDYLAR FORAMEN

The occipital bone, viewed from below. (Spalteholz.)

To the supreme curved line is the bony attachment of the
epicranial aponeurosis; to the superior curved line, most in-
ternally, the biventer cervicis, for the inner third the trapezius,
next the occipitalis, sternocleidomastoid, and splenius capitis.
Between the superior and inferior lines are, internally a large
impression for the complexus, and externally a small one for
the superior oblique. Below the lower line is an inner impres-
sion for the rectus capitis posticus minor, and an outer one
for the major. The ligamentum nuchez is attached to the
protuberance and crest.

The internal surface of the tabular portion shows two ridges
crossing each other, one from the upper angle to the foramen

THE OCCIPITAL BONE Bt)

magnum, one connecting the two lateral angles. Where these
intersect is the internal occipital protuberance, not always
opposite the external. The ridges. mark off four hollows,
the superior and inferior occipital fosse, which lodge the pos-
terior cerebral and the cerebellar lobes. The ridges are grooved
for venous sinuses. ‘The space where the longitudinal sinus
is continued into a lateral one, generally the right, lodges the
torcular Herophili (wine-press of Herophilus). Below this the
vertical ridge is sharp, and named the internal occipital crest.

The condylar portions bear the articular surfaces for the
atlas; these condyles converge toward the front, are doubly
convex, and somewhat everted. At the inner side of each
is a rough impression for a lateral odontoid ligament. Per-
forating the condyle from within out is the anterior condylar
foramen for the hypoglossal nerve and a branch of the ascending
pharyngeal artery. Immediately above this foramen is a
heaping up of bone designated as the eminentia innominata.
Behind the condyle is a posterior condylar fossa; it may be
perforated by a foramen for the passage of a vein from the
lateral sinus; both fossa and foramen are inconstant. External
to the condyle is the jugular process, analogue of a transverse
process; it lies above the transverse process of the atlas, and
it presents in front the jugular notch, which helps form the
jugular foramen; the right notch is usually the larger. The
extremity of the process presents an irregular facet for union
with the temporal bone; this union is osseous at the twenty-
fifth year. The upper surface presents the end of the lateral
sulcus (for the lateral sinus) leading to the jugular notch;
here the posterior condylar foramen opens if present. On
the under surface is attached the rectus capitis lateralis muscle.

The basilar process projects forward and upward in the
middle of the base of the skull and at the top of the pharynx,
increasing in thickness and diminishing in width. Superiorly
is a basilar groove for the medulla, and at either lateral margin
a shallow sulcus for the inferior petrosal sinus. Inferiorly
in the middle line is the pharyngeal tubercle for aponeurotic
attachment of the superior constrictor of the pharynx; on
each side of it are-attached the rectus capitis anticus major
and minor muscles.

The superior border extends on each side from the superior
to the lateral angle, is deeply serrated for articulation with .

36 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

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 portion of the temporal, forming the mastodccipital
suture; the inferior half articulates with the petrous portion
of the temporal, forming the petrodccipital suture; these two
portions are separated from each other 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 postertus, or jugular foramen. ‘This notch is occa-
sionally subdivided into two parts by a small process of bone,
and it generally presents an aperture at its upper part, the
internal opening of the posterior condyloid foramen.

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 fetus 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.

The Parietal Bones

The two parietal bones together form the median portion
of the roof and sides of the skull. Each is roughly quadri-
lateral, and presents two surfaces (external and internal),
four borders, and four angles.

The external surface is convex, smooth, and near its centre
is an eminence called the parietal eminence, or boss. ‘This is
very prominent in young bones.

Through or just below this are the superior and inferior
temporal lines, 2 inch apart; to the superior one is attached
the temporal fascia; to the inferior, the temporal muscle;
below it is the temporal surface for origin of the temporal muscle.
Near the upper border, and # inch (2 em.) from the posterior
angle, the parietal foramen is often found. It is for the exit
of a vein, and usually the entrance of a branch of the occipital

THE PARIETAL BONES 37

artery. The sagittal suture between the two parietal foramina
is inclined to obliteration.

The internal surface is concave; the deepest part is opposite
the parietal eminence, and is called the parietal fossa. This
surface is marked by grooves or canals for the meningeal vessels,
which run upward and backward from the anterior inferior
angle, from the middle and posterior portions of the inferior
border. A shallow half-groove runs along the superior border,
forming with that of the opposite side the channel for the
superior longitudinal sinus. In this half-groove is found the
internal opening of the parietal foramen when it exists. Near
the upper border of the bone are digital depressions for lodge-
ment of the Pacchionian bodies (modified tufts of arachnoid
membrane).

The anterior border, 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 is
thick, and serrated by 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.

The anterior superior angle, thin and pointed, corresponds
with that portion of the skull which in the fetus is membranous,
and is called the anterior fontanelle. 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 fetus this is membranous
and forms a portion of the posterior fontanelle. The posterior
wmfervor angle articulates with the mastoid portion of the tem-
poral bone, the occipital. It generally presents on its inner
surface a small portion of the groove for the lateral sinus.

38 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

The Frontal Bone

The frontal (frons, forehead) arches up and back above the
orbits, forming the forepart of the cranium. It articulates
with twelve bones—the parietals and sphenoid, the malars,
the nasals, superior ‘ maxille, lacrymals, and ethmoid. It
consists of two portions, a superior vertical or frontal and
an inferior horizontal, and presents three surfaces, anterior,
inferior, and cerebral which is continuous in the two portions.

The anterior surface shows the greatest convexity on each
side in the frontal eminence, separated by a slight depression
below from the swperciliary ridge, just above the orbit. In
the middle line between the two ridges is a smooth surface,
the glabella (without hair), also called nasal eminence. The
orbital arch ends in extremities called the internal and eaternal
angular processes; the internal is slightly marked, and articu-
lates with the lacrymal bone; the external is prominent, and
articulates with the malar. At the junction of the inner and
middle third of the arch is the supraorbital notch or foramen
for the supraorbital nerve and vessels. The temporal crest
springs from the outer angular process, and is continuous with
the inferior temporal line on the parietal. Inferiorly are two
thin horizontal lamin, the orbital plates, forming the roof
of the orbits and separated by the ethmoidal notch.

Inferior Surface-—The orbital plates are somewhat tri-
angular, with their internal margins parallel. Close to the
external angular process is the lacrymal fossa, and close to
the inner process is the trochlear fossa for the pulley of the
superior oblique. Between the internal angular processes
is the nasal notch, and from its concavity the nasal process
projects beneath the nasal bones and nasal processes of the
superior maxille, and supports the bridge of the nose. On
the posterior surface of this process are two grooves which
enter into the roof of the nasal fosse; between the grooves is
a median ridge, the nasal spine, which descends in the septum
of the nose above the perpendicular plate of the ethmoid.
Along the inner margins of the ethmoidal notch are irregular
depressions forming the roof of cells in the ethmoid. Each
border is marked inferiorly by two grooves, completing with
the ethmoid the anterior and postervor internal orbital canals;

es

aE OS RUN ae age ga Ot)

THE TEMPORAL BONES 39

the anterior transmits the nasal nerve from the orbit and
anterior ethmoidal vessels; the posterior transmits the pos-
terior ethmoidal vessels. The frontal sinus opens at the root
of the nasal process. It is between the outer and inner tables,
over the root of the nose and divided by a bony septum. Out-
side and behind the orbital surface is a rough triangular area
for articulation with the great wing of the sphenoid.

Cerebral Surface.-—This forms a large concavity for the
anterior lobes of the cerebrum. The orbital plates are convex
and marked by ridges and depressions, and are so thin as to
be transparent; these plates make an angle of about 60 degrees
with the upper part of the bone. From the upper margin
descends the frontal sulcus, running into the frontal crest at
the lower margin. At the base of the crest is usually a groove
converted into the foramen cecum by the approximation of
the ethmoid; this is usually open in children, but blind in adults.
The sides of this surface present grooves for the meningeal
vessels. The thin transverse edge bounding the surface behind
articulates with the greater and lesser wings of the sphenoid.

The border of the vertical portion .is thick, strongly serrated,
bevelled at the expense of the internal table above, where it
rests upon the parietal bones, and at the expense of the external
table at each side, where it receives the lateral pressure of
those bones; this border is continued below into a triangular
rough surface which articulates with the great wing of the
sphenoid. The posterior border of the horizontal portion is thin,
serrated, and articulates with the lesser wing of the sphenoid.

The Temporal Bones

The temporal bone (tempus, time, as hair first becomes gray
in this region, indicating age) helps form the side and base of
the skull and contains the organ of hearing. It presents three
parts—the squamous, mastoid, and pyramidal, which includes
the petrous and tympanic. It articulates with five bones—
posteriorly and internally with the occipital, above with the
parietal, in front with the sphenoid and malar, and below
with the inferior maxilla.

The squamous portion (scale) presents a vertical portion
and a narrow horizontal portion at the base of the skull. It
is limited above by an arched border describing two-thirds

40 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

of a circle. The outer surface is vertical, with a slight convexity,
and forms a part of the temporal fossa. ‘This portion over-
laps the mastoid behind. Above the aperture of the ear is
a vertical groove for the middle temporal artery.

The zygoma is connected with the lower and outer part of
the squamous portion; it is broad at its base, with surfaces
looking up and down; it then twists on itself, so that it has
inner and outer surfaces, upper and lower borders. The upper
border is thin and longer than the inferior, which is short and
arched; the anterior extremity articulates with the zygomatic
process of the malar bone, overlapping it. The zygoma is
attached by two roots; the anterior, continuous with the lower
border, is a broad convex ridge directed inward, called the
eminentia articularis.. At the junction of this with the zygoma
is a tubercle for the external lateral ligament of the lower jaw.
The posterior root prolongs the upper border of the zygoma
as the supramastoid crest, which becomes continuous with
the lower temporal line; it is above the suture between the
squama and mastoid. Between the two roots is the glenoid
fossa; its articular portion is bounded behind by the post-
glenoid process, sometimes called the middle root of the zygoma.
It is strongly developed in some mammals to prevent posterior
dislocation of the lower jaw. The inferior aspect of the hori-
zontal portion presents three districts—the auricular, articular,
and zygomatic, from behind forward. ‘The auricular part
forms the upper concave margin of the external auditory
meatus and a part of the roof of the external ear. The next
portion is the glenoid fossa, which is divided into two parts
by the transverse fissure of Glaser, which is a double cleft.
The posterior part is non-articular, formed by the tympanic
plate and lodging part of the parotid gland. ‘The anterior
part of the fossa is articular, bounded behind by the post-
glenoid process and in front by the eminentia articularis;
it is the fossa mandibularis, concavoconvex for the condyle
of the lower jaw. ‘The first fissure behind the articular fossa
is the petrosquamous, next comes a narrow projection of the
tegmen tympani from the petrous, and next the petrotympanic
fissure or Glaserian fissure proper; it lodges the slender process
of the malleus and tympanic branch of the internal maxillary
artery. Farther in, and external to the Eustachian tube, is
the canal of Huguier, by which the chorda tympani nerve

THE TEMPORAL BONES 41

enters. The outer part of the Glaserian fissure is entirely
closed.

In front of the articular eminence, and separated by a slight
ridge from the temporal surface, is a small triangular infra-
temporal surface, entering into the zygomatic fossa.

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cerebral impressions and meningeal grooves. A narrow hori-
zontal part helps form the anterior wall of the tympanum.
The superior border is thin and fluted, and overlaps the
parietal bone. The parietal notch marks the junction of the
superior border with the mastoid; the squamomastoid suture

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42 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

passes from this notch to the posterior edge of the external
auditory meatus.

The anteroinfertor border is thick, and bevelled above con-
tinously with the upper border at the expense of the inner
surface, below at the expense of the outer—all for articulation

with the great wing of the sphenoid.

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Section through the petrous and mastoid portions of the temporal bone, showing the
communication of the cavity of the tympanum with the mastoid antrum.

The mastoid portion (teat-like) is rough for muscular attach-
ment, and prolonged down behind the auditory meatus as the
mastoid process. At the posterior border is the mastoid foramen,
sometimes foramina, transmitting veins to the lateral sinus
and a mastoid artery from the occipital; the foramen is incon-
stant, and may be in the occipital bone or in the mastodccipital
suture. On the inner side of the mastoid process is the digastric
fossa for attachment of the posterior belly of the digastric,
and internal to this is the sulcus occipitalis for lodgement of
the occipital artery.

The internal surface shows the fossa sigmoidea, which is a
part of the sulcus for the lateral sinus; the mastoid foramen
opens into it. A section of the mastoid portion shows a number

THE TEMPORAL BONES 43

of communicating cells; below in the mastoid process they are
developed after puberty and are arranged vertically. Above
these is the antrum mastoideum, which is a horizontal cellular
cavity, a part of the middle ear; its roof and posterolateral
wall are formed from the petrous portion, and are continuous
with the roof and side of the tympanum. Its anteromedian
wall belongs to the mastoid. Below it connects with the mastoid
cells; its opening into the tympanum is large and on a level
with the foramen ovale, so the floor of the tympanum passes
in front into the Eustachian tube and behind into the mastoid
antrum. ‘The superior border of the mastoid is rough, slopes
back, and articulates with the posteroinferior angle of the
parietal; the posterior border articulates with the occipital
between its lateral angle and jugular process.

The pyramidal portion includes the petrous (stone) and
tympanic (drum) portions.

The petrous portion is a four-sided pyramid with its base
turned out, and its long axis inward, forward, and slightly
downward. The axes of the two portions if prolonged would
meet at the posterior edge of the nasal septum. This portion
presents four borders—superior, inferior, anterior, and posterior;
and four surfaces—anterointernal, posterointernal, anteroexternal,
and posteroexternal, also a base and an apex. The base is
concealed in its upper half by the squamous and mastoid,
and covered below, where these diverge, by the tympanic
portion. The apex is received into the angle between the great
wing of the sphenoid and the basilar process, and presents
the anterior orifice of the carotid canal, and forms the postero-
external boundary of the foramen lacerum.

The anterointernal surface is in the middle fossa of the
skull, and separated from the squamous portion by the fissura
petrosquamosa. ‘This surface presents a little behind its centre
the eminentia arcuata, covering the superior semicircular
canal; in front of this is a groove passing to the hiatus Fallopii,
which leads to the aqueduct of Fallopius; it transmits the
large superficial petrosal nerve and the petrosal branch of
the middle meningeal artery. Outside this are a groove and
small foramen for the small superficial petrosal nerve. Near
the apex the wall of the carotid canal is deficient; above this
is a shallow depression for the Gasserian ganglion. Between
the petrosquamous fissure externally and the hiatus Fallopii

44. OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

and eminence of the superior semicircular canal internally
is a thin lamina which roofs in the tympanum and a common
canal for the Eustachian tube and tensor tympani muscle;
it is the tegmen tympani, a process of the petrous.

The posterointernal surface is in the posterior fossa of the
skull, and continuous with the inner surface of the mastoid.
Near the centre, but nearer the upper than the lower border,
is a large orifice, the porus acusticus internus, leading into a
canal ¢ inch (6 mm.) long, which is the internal auditory meatus;
this is coreaantad by the lamina cribrosa. A transverse ridge,
crista falciformis, separates a small superior from a large inferior
fossa. A faint perpendicular crest divides these into four
fosse. The facial nerve enters the aqueduct of Fallopius
in the upper anterior fossa; the area cribrosa superior is the
perforated part of the upper posterior fossa for the auditory
nerves going to the utricle, superior, and external auditory
canals; below this is the area cribrosa media, conveying an
auditory branch to the saccule; also the foramen singulare,
for a branch to the posterior auditory canal; in the lower
anterior fossa is the tractus spiralis foraminosus, for the cochlear
division of the auditory nerve, ending at the foramen centrale
cochlee.

Behind the auditory meatus is a small slit, the opening of
the aqueduct of the vestibule, transmitting a small artery and
vein and lodging a process of dura mater which encloses the
saccus endolymphaticus; above and between these is a depres-
sion or fissure, the subarcuate fossa, which extends into the
arch of the superior semicircular canal and represents the
floccular fossa of animals.

The posteroexternal surface forms part of the base of the
skull. Beginning at the apex is first a quadrilateral surface
for the origin of the levator palati and tensor tympani muscles,
the lower aperture of the carotid canal, which is first vertical
and then horizontal; vertically beneath the internal auditory
meatus is the three-sided opening of the aqueduct of the cochlea,
which in early life transmits a vein; next behind, is-the jugular
fossa, which forms the jugular foramen when opposite the
jugular notch of the occipital.

In front of the bony ridge, between the carotid canal and
jugular fossa, is a small foramen for Jacobson’s nerve (from
the glossopharyngeal) to the tympanic plexus; this foramen

THE TEMPORAL BONES 45

usually splits to give exit to the small deep petrosal (carotzco-
tympanicus superior) from the tympanic to the carotid plexus.
Externally in the ascending part of the carotid canal is a small
foramen for the caroticotympanicus inferior, a sympathetic
nerve going from the carotid plexus to the tympanic. On
the outside of the jugular fossa is a foramen for Arnold’s nerve
from the pneumogastric; its canal runs through the petrous
transversely and out, and splits into two, an inner to meet
the facial canal, + inch (5 to 6 mm.) above the stylomastoid
foramen, and the other to open at the tympanicomastoid
(auricular) fissure.

Behind the jugular fossa is the jugular facet, for articulation
by synchondrosis with the jugular process of the occipital.
Externally is the styloid process, enclosed between the layers
of the vaginal process. It gives attachment to three muscles
and two ligaments. Between the styloid and mastoid processes
is the stylomastoid foramen, the end of the aqueductus Fallopii,
which passes first out and back over the labyrinth, then in
and back, and then down to terminate here; the stylomastoid
artery enters and the facial nerve leaves this foramen.

The anteroexternal surface is free anteriorly for a short
distance, and articulates with the greater wing of the sphenoid;
posteriorly it is concealed by the tympanic plate.

At the angle between the squamous and petrous portions
is the opening of a canal, the musculotubarius, incompletely
divided into two by a projecting lamella, the cochleariform pro-
cess or septum tube. The upper groove is for the tensor tympani
muscle, and the lower is the bony wall of the Eustachian tube.
This common canal is covered by the tegmen, its inner wall
is the anteroexternal surface of the petrous, and its floor
and outer wall are the tympanic plate. The septum tube
rarely reaches the opposite wall, and rises from the anterior
wall of the carotid canal. This wall is made of two thin lamelle
with diploé between, in which runs the small deep petrosal
nerve. The superior border is grooved for the superior petrosal
sinus, and gives attachment to the tentorium cerebelli. The
posterior border presents on its inner portion a_half-groove
for the inferior petrosal sinus, and externally the margin of
the jugular fossa. From the apex, where a bony projection
often overhangs the inferior petrosal groove, a fibrous band,
the petrosphenoidal ligament, extends to the side of the dorsum

46 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

sellee, and completes a foramen for the inferior petrosal sinus
and sixth nerve. The anterior border has two parts—an outer,
forming the petrosquamous fissure, and an inner free portion
to form the petrosphenoidal suture. The inferior border is
largely concealed by the tympanic and petrous portions; near
the apex it is indistinct, and here the bone is rather three-
sided.

The tympanic portion is beneath the petrous and between
the mastoid and squamous. At birth it is a ring from which
is developed the tympanic plate. The thickened outer extremity
of this plate is the external auditory process, a curved, uneven
lamina forming the anterior and inferior wall of the external ,
auditory meatus and tympanum. The upper margin of the
plate is concealed by the petrous and forms the posterior
boundary of the fissure of Glaser. Its lower margin descends
as a sharp edge, the vaginal process; it is continuous with the
inferior border of the petrous portion.

The Sphenoid Bone

The sphenoid bone (wedge-like) is placed across the base
of the skull near its middle, and binds the other cranial bones
together. It helps form the cavities of the cranium, orbits,
and nasal fossee, and has to do with six pairs of cranial nerves.
It resembles a bat with outstretched wings, and consists of
a body, greater and lesser wings, and pterygoid processes. It
articulates with twelve bones, all those of the cranium, and
five of the face; posteriorly with the occipital and temporals,
anteriorly with the ethmoid, palatals, frontal, and malars;
laterally with the temporals, frontal, and parietals; inferiorly
with the vomer and palatals, and sometimes with the superior
maxille.

The body is followed into two cavities separated by the
sphenoidal septum, and opening anteriorly into the upper and
back part of the nasal fossee behind the superior turbinate
bone.

The superior surface presents in front the ethmoidal spine,
articulating with the cribriform plate of the ethmoid. On
either side of this surface is a slight depression for the olfactory
lobe, and its posterior margin is a transverse ridge—the limbus
sphenoidalis. Behind this, on a lower plane, is the optic groove,

THE SPHENOID BONE 47

terminating on either side in the optic foramen. Next is the
olivary eminence (tuberculum selle), and next the pituitary
fossa, or sella Turcica (Turkish saddle); it is occasionally
bounded in front by two middle clinoid processes; behind is
a square lamina, the dorswm selle or dorsum ephippir (back
of saddle), which slopes posteriorly down and back into the
basilar groove; this slope is the clivxs Blumenbachiw (Blumen-
bach’s hill).

The upper angles of this lamella project over the fossa as
the posterior clinoid processes; the sides are grooved for the
sixth pair of nerves. The sides of the body present a winding
groove curved like the letter f, for the carotid artery in the
cavernous sinus. Behind its commencement, at the lower
lateral angle of the dorsum sell, is the petrosal process of the
sphenoid, to fit against the apex of the petrous; opposite this,
on the other side of the groove, is a tongue-like process, the
lingula sphenordalis.

The posterior surface is quadrilateral, and united to the
basilar process by cartilage in early life, and by bone after the
twenty-fifth year.

The anterior surface is marked in the middle line by the
sphenoidal. crest, which articulates with the perpendicular
plate of the ethmoid. On each side of the crest are a mesial
and a lateral part; the lateral shows half-cells, to be completed
by the ethmoid and orbital plate of the palatal; the mesial
part is smooth, and gives entrance anteriorly into the sphenoidal
sinus, and forms part of the roof of the nose.

The inferior surface presents the rostrum (beak), which
continues the sphenoidal crest and fits between the ale of the
vomer.

The sphenoidal turbinate bones (spongy bones, conche sphenoi-
dales, bones of Bertin) form a considerable part of the anterior
wall of the body of the sphenoid. They are curved and tri-
angular, with apex backward. A small portion of them some-
times appears on the inner wall of the orbit between the ethmoid,
frontal, sphenoid, and palate bones.

Each lateral surface of the body is mostly occupied by the
attachment of the greater wings, except in front a free surface
bounds the sphenoidal fissure and forms the hindermost part
of the inner wall of the orbit.

’ The small or orbital wings (processes of Ingrassias) extend

48 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

horizontally outward on a level with the forepart of the superior
surface of the body; the extremity of each is pointed and comes
almost into contact with the great wing. The inferior surface
forms the upper boundary of the sphenoidal fissure and part
of the roof of the orbit. The anterior border articulates with
the orbital plate of the frontal; the posterior is free, and forms
the boundary between the anterior and middle fosse of the
skull, and terminates internally in the anterior clinoid process.
Between this clinoid process and the olivary eminence is a
semicircular notch in which the carotid groove ends. The
optic foramen perforates the base of the wing, the parts above.
and below being called its roots.

The great or temporal wings project out and up from the
sides of the body; the back part of each is horizontal and fills
the angle between the squamous and petrous portions of the
temporal; from its extremity projects downward the spinous
process. The forepart is vertical and three-sided, and lies
between the cranial cavity, the orbit, and temporal fossa.

The cerebral surface is concave, and forms part of the middle
fossa of the skull.

The external surface (temporozygomatic) is divided by the
infratemporal crest into a lower part looking down into the
zygomatic fossa, and an upper part looking out into the tem-
poral fossa.

The anterior surface looks forward and inward, and consists
of the orbital plate for the external wall of the orbit, and of
a smaller portion above the pterygoid process which looks
into the sphenomaxillary fossa and is perforated by the fora-
men rotundum.

The posterior border near the body bounds the foramen
lacerum, and in its lateral part articulates with the petrous,
forming a groove beneath for the cartilaginous portion of the
Eustachian tube. The external border, commencing at the
spinous process, articulates with the squamous, and above
it overlaps the anterior inferior angle of the parietal bone.
In front of this is a triangular surface formed by the upper
margins of the cerebral, orbital, and temporal surfaces. The
anterior margin articulates above with the malar; below this
is a free horizontal edge separating the zygomatic from the
sphenomaxillary surface. Above and internally the orbital
and cerebral surfaces meet at a sharp border, which forms

THE SPHENOID BONE 49

the inferior boundary of the sphenoidal fissure, and often
shows a bony projection for the lower head of the external
rectus.

The pterygoid (wing-like) processes project downward and
forward (angle of 110 to 115 degrees) from the junction of the
body and great wings. Some consider them to rise from two
roots, one representing a transverse process, one a-rib, and
the Vidian canal, the costotransverse foramen. Each consists
of two plates united in front and diverging behind, forming
the pterygoid fossa for the origin of the internal pterygoid
muscle. The external plate is broad and extends out and
back, and gives origin by its outer surface to the external
pterygoid muscle. The internal plate is long and narrow, and
prolonged below into the hamular process (hook-like), around
which plays the tendon of the tensor palati, muscle. The
upper part of the inner plate turns in beneath the body, and
remains distinct as a slightly raised edge, the vaginal process,
which meets the everted margin of the vomer. At the angle
of the vaginal process with the internal plate is a groove which,
with the sphenoidal process of the palate, forms the pterygo-
palatine canal. Posteriorly, at the base of the inner plate,
is the pterygoid tubercle, to the inner side of and below the
Vidian canal; between this and the pterygoid fossa is the
scaphoid fossa for the origin of the tensor palati muscle. Lower
down, on the posterior margin of the plate, is the processus
tubartus, which supports the cartilage of the Eustachian tube.
Between the lower ends of the plates is the pterygoid notch,
occupied by the pyramidal process of the palate bone.

Fissures and Foramina of the Sphenoid.—Kach half pre-
sents a fissure, four foramina, and a canal. The sphenoidal
fissure is the oblique interval between the great and small
wings, closed externally by the frontal bone. It opens into
the orbit and transmits the third, fourth, ophthalmic division
of the fifth, and the sixth cranial nerves, some sympathetic
filaments from the cavernous plexus, the orbital branch of
the middle meningeal artery, recurrent branch of the lacrymal
. artery, and the ophthalmic vein. Above and to the inside
of this fissure is the optic foramen, piercing the base of the
small wing and transmitting the optic nerve and ophthalmic
artery. The foramen rotundum pierces the great wing below
the sphenoidal fissure and transmits the superior maxillary

4

50 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

nerve. Behind and external to this is the foramen ovale, near
the posterior margin of the great wing, sometimes incomplete;
it transmits the inferior maxillary nerve, the small meningeal
artery, and sometimes the small superficial petrosal nerve.
The foramen spinosum pierces the great wing near the posterior
angle, and transmits the middle meningeal artery and nervus
spinosus, a recurrent. branch of the inframaxillary. From
the foramen spinosum projects backward a thin horizontal
sphenopetrosal lamina, which reaches the upper border of the
Kustachian canal on the petrous.

The Vidian canal pierces the base of the internal pterygoid
plate anteroposteriorly; it passes from the foramen lacerum to
the sphenomaxillary fossa, transmitting the Vidian nerve and
vessels.

A spicule of bone may connect the middle clinoid process
(when present) with the anterior, forming a caroticoclinoid
foramen for the carotid artery. Interclinoid ligaments are
normally present beneath the dura. The outer pterygoid

plate may be connected by bone or ligament with the spinous —

process. The foramen of Vesalius for an emissary vein is some-
times present on the inner side of the foramen ovale. The
canaliculus innominatus is sometimes present for the small
superficial petrosal nerve internal to the foramen spinosum.

The Ethmoid Bone

The ethmoid (sieve-like) projects down between the orbital
plates of the frontal, and enters into the formation of the
cranium, orbits, and nasal fossee.

It articulates with thirteen bones—fifteen including the
sphenoidal turbinates—the frontal, sphenoid, and vomer,
the nasals, lacrymals, superior maxillee, palatals, and inferior
turbinate bones.

It consists of thin plates enclosing irregular cells—a vertical
plate and two lateral masses united above by the horizontal
cribriform plate. The vertical plate forms the upper third of
the nasal septum, and presents grooves and canals for the
olfactory nerves. Its superior border appears in the cranial
cavity as the crista galli (cock’s comb); posteriorly this process
is thin, and anteriorly is broadened into two alar processes,
between which is usually a groove completing the foramen

-~-see le eee

THE ETHMOID BONE 51

cecum with the frontal. If the vertical plate be deflected
below the cribriform, the crista galli is inclined in the opposite
direction. The anterior border of the plate articulates with
the nasal spine of the frontal and with the nasal bones; the
inferior border in front with the triangular cartilage of the
nose, and behind with the vomer; the posterior margin with
the sphenoidal crest (Fig. 9).

Each lateral mass or labyrinth encloses three sets of spaces—
the anterior, middle, and posterior ethmoidal cells; they do not
communicate with each other. Externally is the paper-like
orbital plate, or os planum (lamina papyracea), closing in the
middle and posterior cells; it articulates in front with the
lacrymal, behind with the sphenoid, above with the frontal,
and below with the superior maxilla and palate bones.* On
this aspect below the plate is a groove belonging to the middle
meatus of the nose; it turns up anteriorly, and is continued
by the infundibulum through the anterior ethmoidal cells
to the frontal sinus; the middle cells open into the horizontal
part of the groove. The lateral mass in front of the orbital
plate is covered in by the lacrymal; from this part the wneinate
process curves back, down, and out, helping to close the orifice
of the antrum; it articulates below with the ethmoidal process
of the inferior turbinate.

The inner aspect of each lateral mass is in the outer wall
of the nasal fossa. Above is a channel, the superior meatus,
passing from behind to about the middle of the bone; it com-
municates with the posterior cells. The plate overhanging it
is the swpervor turbinate process or superior spongy bone (concha
suprema); the space above that is in the roof of the nose.
Below the groove is the inferior turbinate process of the ethmoid
or middle spongy bone (concha inferior), rolling convexly toward
the nasal fossa; it forms the lower border of the lateral mass.

Two grooves cross the upper margin of the lateral mass,
forming with the frontal the two internal orbital or anterior
and posterior ethmoidal canals. Posteriorly the mass is anky-
losed with the sphenoidal spongy bone.

The cribriform plate occupies the ethmoidal notch of the
frontal. It presents the olfactory groove on each side of the
erista galli and foramina for the olfactory nerves; the foramina
of the middle set are few and are simple perforations; in the
external and internal sets they are more numerous, and are

02 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

orifices of small canals which subdivide on the vertical plate
and lateral mass. Anteriorly is a fissure close to the base of
the crista‘galli, and external to it a notch connecting with
the anterior internal orbital canal for the passage of the nasal
nerve and anterior ethmoidal artery from the orbit to the
cranium, and thence to the nasal fossa.

THE BONES OF THE FACE

The Superior Maxillary Bones

The superior maxilla is the principal bone of the face, sup-
porting the upper teeth of one side, helping to form the hard
palate, floor of the orbit, floor and outer wall of the nasal
fossa. It articulates with nine or ten bones—with its fellow,
with the nasal, frontal, lacrymal, ethmoid, palate, malar,
vomer, inferior turbinate, and sometimes with the sphenoid
at the outer extremity of the sphenomaxillary fissure. There
are a body and four processes for description. The body is a
hollow half-cylinder, presenting an external surface subdivided
into an anterior and a posterior, an internal and a superior;
the processes are nasal, alveolar, malar, and palatal.

The body encloses the antrum of Highmore, which opens
into the middle meatus of the nose. The anterior or facial
surface is marked below by eminences corresponding to fangs
of the teeth. Internal to the eminence for the canine is the
incisor or myrtiform fossa; external to it is the deeper canine
fossa; above the latter, below the margin of the orbit, is the
infraorbital foramen. ‘The inner margin of this surface is cut
by the nasal notch, the sharp edge of which is prolonged below
into the anterior nasal spine.

The posterior or zygomatic surface looks into the zygomatic
and sphenomaxillary fossze; it presents two or more apertures »
of the posterior dental canals; below and posteriorly is a rough
tuberosity, the mazillary tuberosity. At the junction of this
surface with the nasal and orbital is a small triangular space
on which the orbital process of the palate rests, the palatine
trigone (Henle).

The internal or nasal surface (Fig. 8) presents in front the
inferior turbinate crest; below it is the smooth concavity of

THE SUPERIOR MAXILLARY BONES 53

the inferior meatus; above it a small surface forming the atrvwm
(entry) of the middle meatus. Behind the nasal process is
the lacrymal groove, } inch long, inclined down and out, open-
ing into the inferior meatus; the groove is converted into the
canal of the nasal duct by the lacrymal and inferior turbinate.
Behind it is the opening of the antrum; above this are small
half-cells belonging to the middle ethmoidal set. Behind the
opening of the antrum the surface is rough for articulation
with the palate bone, and traversed by a groove running down
and forward, forming with the palate the posterior palatine
canal, for the posterior palatine vessels, anterior and external
palatine nerves. |

The orbital surface is triangular and flat; externally is a
rough surface for the malar; internally is first the lacrymal
notch, and behind it a pretty straight margin for the ethmoid
and orbital process of the palate. The posteroexternal border
is free and bounds the sphenomaxillary fissure. The ifra-
orbital groove commences well back on this surface, leading
to a canal of the same name, which opens anteriorly at the
infraorbital foramen; from the canal are given off the anterior
and middle dental canals in the substance of the bone.

The nasal process projects up, in, and back; its external
surface is smooth; the higher part of the inner surface com-
pletes the anterior ethmoidal cells; below this the surface is
crossed by the superior turbinate crest (agger nasi) for the
inferior turbinate process of the ethmoid (middle spongy bone).
The anterior border articulates with the nasal bones and above
with the frontal; posteriorly is a continuation of the lacrymal
groove, bounded internally by a sharp edge articulating with
the lacrymal, and externally by a smooth border; where this
border joins the orbital surface is the lacrymal tubercle.

The alveolar process is thick and hollowed into eight alveoli.
The malar process is triangular, continuous in front and behind
with the facial and zygomatic surfaces of the body. Superiorly
it is rough for the malar; the inferior border forms a thick
buttress opposite the first molar.

The palate process with its opposite forms three-fourths
of the hard palate. Above, it is concave transversely, and
forms part of the floor of the inferior meatus. Below, it is
arched, and shows lateral grooves for nerves and vessels; its
posterior extremity falls short of that of the alveolar arch,

\

54 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

and the space is filled by the palate bone. The inner border
rises into a nasal crest which receives the vomer; in front a
more elevated part is the «incisor crest,. prolonged into the
anterior nasal spine. By the site of the incisor crest is a fora-
men, becoming a groove; when the bones are united there is
one orifice below, with right and left branches above, called
the incisor foramina, or foramina of Stetson, for the transmis-
sion of arteries. The lower aperture is the anterior palatine
fossa; in the middle line, opening into it, are the foramina of
Scarpa, the left nasopalatine nerve passing through the anterior
one and the right through the posterior. From the anterior
palatine fossa are seen two sutures passing to the interval
between the canine and lateral incisor tooth; the sutures are
to be seen in the inferior meatus. They mark off the inter-
maxillary bone, and include the whole thickness of the alveolar
processes, the nasal spine, and sockets for the incisor teeth.
No trace of the suture is seen on the facial surface, as an out-
growth, the incisor process, forms the front wall of the incisor
sockets. :

The maaillary sinus, or antrum, is irregularly pyramidal;
the base is at the nasal surface of the body and the apex extends
into the malar process. Its aperture is closed in part by the
uncinate process of the ethmoid, the ethmoidal process of the
inferior turbinate, and the maxillary process of the palate
behind; the lacrymal in front rarely assists. The alveolus
of the first molar is most prominent in the floor.

The Palate Bone

This bone is L-shaped, and forms the back part of the hard
palate and the lateral wall of the nose between the superior
maxilla and internal pterygoid plate. It presents a horizontal,
a vertical plate, and three processes. It articulates with six
bones—its fellow, the superior maxilla, the ethmoid, sphenoid,
vomer, and inferior turbinate.

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 nostril. The infertor 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

A PR a SO. ee i ee ee ae -

THE PALATE BONE 55

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 maxillary 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 uvule. The eaternal border
is united with the lower part of the perpendicular plate almost
at right angles. The internal border, the thickest, is serrated
for articulation with its fellow of the opposite side; its superior
edge is raised into a ridge which, united: with the opposite
bone, forms a crest in which the vomer is received.

The vertical plate is thin; its nasal surface is divided into
two parts by the inferior turbinate crest for the inferior turbi-
nate bone; the middle meatus is above it and the inferior
below. At the upper part is the superior turbinate crest for
the middle spongy bone, and above this a groove in the superior
meatus. The external surface presents above and behind a
smooth surface, forming the inner wall of the pterygomaxillary
fissure, and leads to the posterior: palatine groove. In front
of the groove the surface is applied to the superior maxilla
and sends the mavillary process forward, closing in the lower
back part of the opening of the antrum. Behind the groove
the surface articulates below with the maxilla and above with
the pterygoid process.

The pyramidal process or tuberosity juts out behind and
fits between the pterygoid plates; it presents posteriorly a
smooth middle district entering into the pterygoid fossa;
internal to it is a groove for the internal pterygoid plate, and
externally a rough area for the external plate. Part of the
tuberosity appears in the zygomatic fossa. Inferiorly, close
to the horizontal plate, are the postervor and eaternal accessory
palatine canals.

The orbital process rests on the anterior margin of the verti-
cal plate; it has five surfaces, three articular, and two, the
superior and external, are free.

56 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

The superior surface forms the posterior angle of the floor
of the orbit; the external looks into the sphenomaxillary fossa;
the anterior articulates with the maxilla, the internal with the
ethmoid, and the posterior with the sphenoid. The process is
usually hollow, and completes a posterior ethmoidal cell or
may open into the sphenoidal sinus.

Kia. 8

Nasal process.
Superior tur-
binated crest.

Orbital process.

Spheno- —
palatine for.
Sphenoidal ~
process, =
' Superior tur-
binated crest.

Inferior tur-
binated crest.

Inferior tur-
binated crest.

Anterior nasal
spine.

Palate bone in situ.

The sphenoidal process curves up and in from the posterior
part of the vertical plate. It has three surfaces: thé posterior
is in contact with the under surface of the body of the sphenoid,
and is grooved for the pterygopalatine canal; the internal sur-
face looks into the nasal fossa and touches the ala of the vomer;
the external looks into the sphenomaxillary fossa.

The sphenopalatine notch is between these two processes,
converted by the body of the sphenoid into a foramen of the
same name.

eee

THE VOMER 57

The Vomer

The vomer (ploughshare) is thin and quadrilateral, and
placed vertically between the nasal fossee. The upper and
posterior borders, and the anterior and. inferior, are of nearly
equal lengths. It articulates with six bones—the sphenoid,
ethmoid, two palate, two superior maxillary—and with the
septal cartilage of the nose.

Fra. 9

Frontal sinuses.

Crista galli.

Sphenoidal sinuses.

Perpendicula
plate of eth-
moid,

Space for
triangular
cartilage
of septum.
Vomer.

Rostrum of
sphenoid.

~—Palate process.

Int. pterygoid
plate.

Vomer in situ.

Each surface presents a groove leading the nasopalatine
nerve to the foramen of Scarpa. The superior border divides
into two ale, which receive the rostrum of the sphenoid be-

58 TOSHOE MEE: OR ANATOMY OF OSSEOUS SYSTEM

tween them; each ala meets the vaginal process of the sphenoi
and the sphenoidal process of the palate.

There are usually three vomerobasilar canals—a median,

between ala and rostrum for nutrient vessels; an upper lateral
one, between the body of the sphenoid and root of the vaginal
process, carrying vessels to the sphenoidal cells; a lower lateral
one, between the body of the sphenoid and the sphenoidal
process of the palate, carrying vessels and nerves from the
nasal and sphenomaxillary fosse to the upper pharynx.

The anterior border is grooved in its lower half for the septal
cartilage; in its upper half it is ankylosed on one or both sides,
usually the right, with the perpendicular plate of the ethmoid.
At the inferior anterior angle is a short vertical edge to fit
in behind the incisor crest of the maxille; from its upper end
a process runs forward in the groove of the crest, and from its
lower end a point may project down between the incisor fora-
mina. The inferior border articulates with the nasal crest of
the maxille and palate bones; the posterior border is rounded,
thin, concave from above downward, and free, and separates
the posterior nares.

The Malar Bones

This cheek bone separates the orbit from the temporal
fossa and articulates with four bones—the frontal, sphenoid,
temporal, and superior maxillary. It is quadrangular, with
the angles directed vertically and horizontally; it may be
thought of as formed of a triangular orbital plate united at
a sharp angle to a quadrangular malar plate. The outer swrface
presents a little below the centre the malar tuberosity, and above
this the orifice of the malar canal. The inner surface is concave,
looks into the temporal and zygomatic fosse, and presents a
roughness in front and below for articulation with the superior
maxilla. The wpper angle or frontal process is serrated for the
external angular process of the frontal. The temporal border
behind this is sinuous and continuous with a upper border
of the zygoma.

The posterior angle or temporal process has the zygoma rest-
ing upon and articulating with it. The posteroinferior border,
the masseteric, completes the lower edge of the zygomatic
arch; the anteroinferior border, the maxillary, and a rough

7,

THE MALAR BONES 59

part of the inner surface, articulate with the malar process
of the superior maxilla. The orbital border is excavated, and
forms a great part of the orbital margin, ending internally
just above or inside the infraorbital foramen. From this
the orbital process projects back, forming the forepart of the
outer wall, and enters the external portion of the floor of the

Fria. 10

Zygoma-
tic proc. \\

Malar bone in situ.

orbit, articulating with the great wing of the sphenoid and
orbital plate of the superior maxillary. On the orbital surface
are the openings of two canals—the temporal opening on the
temporal surface, and the malar opening on the facial; they
transmit the temporomalar branches of the superior maxillary
nerve.

The anterior extremity of the sphenomaxillary fissure may
be completed in one of three ways—by the malar in more than
half the cases, by the articulation of the sphenoid with the
superior maxilla, or by a Wormian bone.

The antrum of Highmore may extend into the malar.

7 60 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

The Nasal Bones

The two form the bridge of the nose, and each articulates
with four bones—the frontal, superior maxillary, ethmoid,
and its fellow. They are narrow and thick above, broader
and thinner below. They articulate above with the inner
part of the nasal notch of the frontal.

The inferior border is free, and gives attachment to the
lateral nasal cartilage; it usually has a small notch near the
inner end. ‘The external border is longest, and articulates
by means of small teeth with the nasal process of the superior
maxilla.

The internal border meets its fellow in a somewhat irregular
internasal suture, which commonly deviates to one side at
the upper end. Posteriorly the two form a crest which rests
from above down on the nasal process of the frontal, the ver-
tical plate of the ethmoid, and the septal nasal cartilage. The
facial surface is convex below and concave above, and presents
vascular foramina.

The posterior surface is concave, and a little external to
its centre is a longitudinal groove for the nasal nerve.

The Lacrymal Bones

The lacrymal, or os unguis, is a thin scale, like a finger
nail, at the anterior and inner part of the orbit. It articulates
with four bones—frontal, ethmoid, superior maxilla, and
inferior turbinate. It presents two surfaces and four borders.
Its external surface is divided by a vertical ridge, the laerymal
crest; in front of it is the lacrymal groove, and this part is
prolonged below as the descending process to articulate with the
inferior turbinate; behind the crest the surface is smooth and
forms part of the orbit, and is produced below into the hamular
process, which comes forward into the lacrymal notch of
the superior maxilla and bounds the outer side of the orifice
of the nasal duct. The internal surface is a depressed furrow
completing above some of the anterior ethmoidal cells, and
below it looks into the middle nasal meatus.

Of the four borders, the anterior is the longest and articulates
with the nasal process of the superior maxillary bone. The

hele AG

THE INFERIOR TURBINATED BONES 61

postervor, 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 articulates with the
orbital plate of the superior maxillary bone; the anterior por-
tion is prolonged downward into a pointed process which
articulates with the lacrymal process of the inferior turbi-
nated bone and assists in the formation of the lacrymal canal
as described under eaternal surface.

Fie. 11

Nasal proce.

Sup. tur bi-
nated crest.

Ethmoidal
process. J

f/ _ Lacrymal

} proc.

Inf. turbi-
nated crest.

Inferior turbinated bone and lacrymal bone in situ.

The Inferior Turbinated Bones

The inferior turbinate or spongy bone projects like a shell
into the nasal cavity, separating the middle from the inferior
meatus. Its convexity looks in and its lower margin is rolled

62 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

on itself. Its attached margin articulates in front with the
inferior turbinate crest of the superior maxilla, and then ascends
abruptly as the lacrymal process to complete the lacrymal
canal. Behind this, and nearer the back than the front, the
bone is folded down as the mazilary process, looking over the
aperture of the antrum, and forming part of its inner wall;
on the upper border: of this process is the ethmoidal process,
which articulates with the uncinate of the ethmoid. Posteriorly,
the bone is attached to the inferior turbinate crest of the palate;
the posterior extremity is elongated and pointed, the anterior
flat and broad.

The bone articulates with the superior maxilla, lacrymal,
ethmoid, and palate. No muscle is attached to it. The negro
may have four turbinate bones.

The Inferior Maxillary Bone (Mandible)

The lower jaw, or mandible, is the strongest bone of the face,
and articulates with the glenoid fosse of the temporals. It
consists of a curved horizontal portion or body and two ascend-
ing branches or rami. The body shows in the median line in
front a faint vertical ridge, the symphysis of two originally
distinct pieces; this expands below into the mental protuberance,
which presents a prominence on each side called the mental
tubercle. The superior or alveolar border is hollowed out into
sockets for teeth. The inferior border, or base, is thick and
rounded, and projects beyond the superior. Below the incisor
teeth is the incisor fossa; more externally is the mental foramen
midway between the upper and lower borders, under the
interval between the two bicuspids; it is the anterior opening
of the dental canal. Below the foramen the eaternal oblique
line runs up and back from the mental tubercle to the anterior
margin of the ramus behind the teeth. The deep surface of
the body presents inferiorly near the symphysis an oval fossa
for the attachment of the digastric muscle; above it are the
mental spines, the lower being a median ridge.for the genio-
hyoid muscles, and the upper a pair of tubercles for the genio-
hyoglossi; there may be four tubercles (: :) or two (*') or a
vertical ridge (1) or one prominence (*). Above them a small
foramen penetrates the bone, and above this a narrow median
groove marks the symphysis. Below the mental spines, and

THE INFERIOR MAXILLARY BONE 63

passing up and back to the ramus, is the internal oblique line
or mylohyoid ridge, for the mylohyoid muscle and a slip of the
superior constrictor of the pharynx. Above this line is a fossa
for the sublingual gland, and below it another for the sub-
maxillary.

The ramus is thinner than the body, and where its posterior
border meets the base it forms the slightly everted angle.
The external surface is flat, and near the angle it shows oblique
lines for tendinous attachment of the masseter muscle. At
the centre of the internal surface, on a level with the crowns
of the molar teeth, is the inferior dental foramen, leading to the
dental canal; the inner margin of the foramen is sharp anteriorly,
and called the lingula mandibule. Beginning at the notch
behind the lingula is the mylohyoid groove (sometimes a canal),
terminating below the hinder end of the mylohyoid ridge.
Behind and below this is a rough surface for the internal ptery-
goid muscle. On the upper border of the ramus are two processes
—the condyle for articulation and the coronoid for muscular
attachment; they are separated by the semilunar or sigmoid
notch. The condyle passes up from the posterior part of the
ramus, supported on a constricted neck, on the front of which
internally is a depression for the external pterygoid muscle
4 inch; 8 mm.); below the articular surface there may be |
an external tubercle for the external lateral ligament. The
condyle is convex, transversely elongated, and the axes of
the two would meet at the anterior margin of the foramen
magnum. ‘The coronoid process passes up from the forepart
of the ramus, inclined out and somewhat beak-shaped; by its
apex, sharp margins, upper and anterior part of the external

surface, and inner surface, it gives attachment to the tem-

poral muscle.

The anterior border of the ramus shows three oblique ridges—
an external one to the end of the external oblique line; internal
to that is a groove bounded posteriorly by a ridge passing
from the internal oblique line to the middle aspect of the coro-
noid; at the lower part of the groove, extending a short distance
to the outer side of the alveolus, is the third or buccal line.

The lower jaw consists of a thick shell of compact tissue
enclosing cancellous tissue; the dental canal in its posterior
two-thirds lies close to the inner compact layer; it is prolonged
beyond the mental foramen under the canine and _ incisor

64 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

teeth. There may be two dental canals. The angle of the
jaw in the adult is about 120 degrees; in infancy, 140 degrees
or more; in old and toothless jaws, it is increased. These
changes are due to development, absorption of the alveolar
arch, and strength of the masseter muscles.

The Skull as a Whole

THE SUTURES OF THE SKULL

The skull bones are closely fitted by uneven edges, there
being interposed a little fibrous tissue continuous with the
periosteum; the dentations are confined to the external table,
the edges of the inner table lying only in apposition. The
lower jaw-has a movable articulation, differing from the others.

The sutures around three sides of the parietal bones have ©

special names—between the two is the sagittal, behind them
the lambdoid, in front of them the coronal.

All the sutures may be arranged in three groups—a median
longitudinal, a lateral longitudinal, and a vertical transverse.
The first consists of the sagittal, and in the infant the frontal;
the second begins in the median line in front, and includes
on each side the frontonasal, frontomaxillary, frontolacry-
mal, frontoethmoidal, frontomalar, frontosphenoidal, spheno-
parietal, squamoparietal, and mastoparietal; the third comprises
the coronal and sphenosquamous, the lambdoid and occipito-
mastoid, and also the transverse sutures at the base of the
skull.

After about thirty years of age many sutures close, union
taking place on the inner surface first; the parts to close first
are the sagittal suture between the parietal foramina and
the lower ends of the coronal suture.

Wormian Bones.—These ossa triquetra, ossa suturarum,
are irregular ossifications between cranial bones rarely found
in the face. They are usually symmetrical, and are most
common in the lambdoid suture, occupying the place of the
superior angle of the occipital bone; may be at either anterior
angle of the parietals. They usually include only one plate
of the skull.

a ey

THE SKULL AS A WHOLE 65

Toe EXTERNAL SURFACE OF THE SKULL

The external surface may be divided into superior or vertex,
inferior, or base, anterior, or face, and lateral regions.

The superior region, or vertex, extends from the supra-
orbital margins to the superior curved line of the occiput,
bounded laterally by the temporal lines. It is a smooth,
convex surface covered by muscle and aponeurosis. The
greatest transverse diameter of the skull is at the junction
of the posterior and middle thirds, viz., 53 inches (140 mm.);
the greatest longitudinal diameter from the under margin
of the frontal bone to the external occipital protuberance is
64 inches (170 mm.).

The anterior region, or face, presents the openings of the
orbits, the bridge of the nose, below that the anterior nasal
aperture (apertura pyriformis), presenting the anterior nasal
spine below. Below the aperture are the incisor fosse of the
upper jaw, below the orbits the canine fosse, and external
to them the malar prominences. The lower jaw completes
the skeleton of the face with its incisor fosse, mental promi-
nence, etc.

In a nearly vertical line on either side are three foramina
for the exit of some part of the three divisions of the fifth
cranial nerve, viz., the supraorbital, infraorbital, and mental.
There are also the malar foramina on the malar bone.

The orbits are pyramidal fosse, somewhat quadrihedral,
with their bases turned forward and out; their inner walls
are nearly parallel, and their outer walls diverge at nearly
right angles to each other. Each is formed of seven bones,
or eleven for the two—the frontal, sphenoid, malar, superior
maxillary, lacrymal, ethmoid, and palate. The roof of each
is formed by the orbital plate of the frontal and small wing
of the sphenoid; the floor by the malar, superior maxilla, and
orbital plate of the palate; the inner wall by the nasal process
of the superior maxilla, the lacrymal, ethmoid, and body of
the sphenoid; the outer wall by the malar and great wing of the
sphenoid. The sphenoidal fissure at its inner part occupies
the apex of the orbit; its outer extremity lies between the
roof and outer wall.

The optic foramen is internal to and above the fissure. In

5

66 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

the angle between the external wall and floor is the spheno-
maxillary fissure, bounded by the palate, superior maxilla,
malar, and sphenoid bones; it leads into the sphenomaxillary
fossa at its back part and the zygomatic fossa at its forepart.
Passing forward from the margin of this fissure is the com-
mencement of the infraorbital canal. On the inner wall in
front is the lacrymal groove, leading to the canal of the nasal
duct, and farther back, between the frontal and ethmoid, are
the anterior and posterior internal orbital or ethmoidal canals.
At the junction of the inner and middle thirds of the anterior
margin of the roof is the supraorbital foramen or notch. Within
the external angular process is the lacrymal fossa, and on the
outer wall are the temporal and malar canals.

The lateral region of the skull presents from behind forward
the mastoid portion, the mastoid foramen, the external audi-
tory meatus, the glenoid fossa with the condyle of the lower
jaw, eminentia articularis, coronoid process, and zygomatic
arch. Above this arch is the temporal fossa, and below it,
separated by the infratemporal crest, is the zygomatic fossa.

The temporal fossa, occupied by the temporal muscle, is
bounded above by the temporal crest of the frontal and the
lower temporal line of the parietal; the latter runs into the
supramastoid crest, and that into the zygomatic arch.

The zygomatic or infratemporal fossa contains a part of the
temporal muscle, the external and internal pterygoids, the
internal maxillary artery, and the inferior maxillary nerve.
Some of its boundaries are indefinite; externally is the ramus
of the lower jaw; superiorly the great wing of the sphenoid,
showing the foramen ovale and spinosum, also a small part
of the squamous portion of the temporal; anteriorly is the
lower part of the malar and zygomatic surface of the superior
maxilla; the inferior limit is the extremity of the external
pterygoid plate and alveolar border of the superior maxilla.
The inner wall is formed by the external pterygoid plate;
the posterior limit is the eminentia articularis and posterior
border of the external pterygoid plate.

Inferiorly the pterygoid process approaches close to the
superior maxilla, but is prevented from meeting by the
pyramidal process of the palate. Above they are separated
by the pterygomazillary fissure, leading into the sphenomaxillary

ee,

THE SKULL AS A WHOLE 67

fossa. Running at right angles to the fissure is the spheno-
maxillary fissure opening into the orbit.

The sphenomaxillary fossa is a small triangular space at
the angle of junction of the above-named fissures, placed
beneath the apex of the orbit. It is bounded above by the
body of the sphenoid, in front by the superior maxilla, behind
by the base of the pterygoid, and internally by the vertical
plate of the palate. It has three fissures terminating in it—
the sphenoidal, sphenomaxillary, and pterygomaxillary. It
communicates with four fosse—the orbital, nasal, zygomatic,
and middle fossa of the base of the skull; and has opening into
it five foramina—three from behind, the foramen rotundum,
the Vidian, and the pterygopalatine canals; internally is the
sphenopalatine foramen, and inferiorly the posterior palatine
canals, and occasionally the accessory posterior palatine canals.

The external base of the skull (“base of skull’ properly
means base of the cranium, and does not include the facial
bones; the usual description, however, will be followed, and
the inferior maxilla included) is divisible into three parts—
anterior, middle, and posterior. The anterior division consists
of the palate, alveolar arches, and body of the inferior maxilla.
It is traversed longitudinally by a median suture, and trans-
versely by that between the maxillary and palate bones. In
front is the anterior palatine fossa, with the four foramina
opening into it; farther back are the under surface of the
tuberosity of the palate, the apertures of the posterior and
external palatine canals, and the posterior nasal spine.

The middle division extends back to the foramen magnum,
and is called the guttural fosse (relating to the throat). In
the midline is the basilar process, and in front of that the
body of the sphenoid covered by the ale of the vomer. On
each side the petrous portion reaches to the extremity of the
basilar process, and between the petrous and squamous is
the back part of the great wing of the sphenoid. In front
are the posterior nares, or choane (funnels), separated by the
vomer, bounded above by the sphenoid, below by the hori-
zontal plates of the palate bones, and laterally by the internal
pterygoid plates. On each side are the pterygopalatine and
Vidian canals, the scaphoid and pterygoid fosse. <A line from
the external pterygoid plate to the spine of the sphenoid sepa-
rates this surface from the zygomatic fossa; internal to this

68 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

line is the groove for the cartilaginous part of the Eusta-
chian tube. Between the apex of the petrous, the basilar
process, and the sphenoid is the foramen lacerum (this is the
only foramen properly called “lacerated”). This with the
petrobasilar fissure is filled with fibrous tissue, and may con-
tain Wormian bones. Passing back and out from this is the
petrosphenoidal fissure, the styloid and vaginal processes,
and the stylomastoid foramen; more internally are the anterior
condylar foramina and the jugular fossa. This fossa is divided
into three compartments by processes of the dura mater. The
inferior petrosal sinus is in the anterior one, the lateral sinus,
some ascending pharyngeal and occipital arteries in the pos-
terior one, and the ninth, tenth, and eleventh cranial nerves
in the middle one.

Other points have been described with the temporal bone.

The posterior division presents on either side of the foramen
magnum the occipital condyle, jugular process, occipital
sulcus, digastric fossa, and mastoid process. Behind the
foramen magnum is the tabular part of the occipital up to
the superior curved line. Into this posterior division are
inserted all the muscles running up to the skull from the ribs,
spines, and transverse processes.

THe INTERIOR OF THE CRANIUM

The interior of the cranium presents impressions for the
cerebral convolutions. The thickness of the skull-cap, or
calvaria, is + to } inch. The base of the skull varies in thick-
ness, thinnest at the cribriform and orbital plates, where there
is no diploé; also thin in the inferior occipital fossa, in the
squama, and glenoid fossa. The inner surface of the calvaria
is dome-like, formed by the frontal, parietal, and occipital
bones. It is marked by the superior longitudinal sulcus, small
meningeal grooves, and Pacchionian fosse. The only apertures
are the inconstant parietal foramina. )

Tue INTERNAL BASE OF THE SKULL

This surface is divided into three fossse—anterior, middle,
and posterior.

The -anterior fossa is formed by the orbital plates of the
frontal, the cribriform of the ethmoid, the small wings and

Db aie ioe

THE SKULL AS A WHOLE 69

part of the body of the sphenoid; it supports the frontal lobes
of the cerebrum. It is convex laterally, with a slight con-
cavity over the cribriform plate excepting where the crista
galli stands up separating the olfactory grooves. Here are
found the foramen cecum, the olfactory foramina, openings of
the internal orbital or ethmoidal canals, and the foramen for the
nasal nerve.

The middle fossa is on a lower level than the anterior, and
consists of a median and two lateral parts. The median part
is narrow, presenting the olivary eminence, the sella Turcica,
and limited behind by the dorsum selle. Laterally is the
great wing of the sphenoid, the squama, and anterointernal
surface of the petrous portion. This lodges the temporal
lobe of the cerebrum. ‘The foramina present are the optic,
sphenoidal fissure, foramen rotundum, ovale, spinosum, lacerum,
and hiatus Fallopu.

The posterior fossa is deeper and larger than the others,
and lodges the cerebellum, medulla, and pons. The occipital
bone, the petrous and mastoid portions of the temporal, postero-
inferior angle of the parietal, and body of the sphenoid enter
into it. In the centre is the foramen magnum, and on each
side, in a nearly vertical line, are the anterior condylar fora-
men, jugular foramen, and internal auditory meatus: Behind
the jugular foramen is the posterior condylar (if present),
and higher up the mastoid foramen, both opening into the
lateral sulcus. By the internal auditory meatus the facial
and auditory nerves, the portio intermedia, and the auditory
vessels leave the cranium.

Besides these points mentioned there are grooves for arteries
and venous sinuses.

That for the middle meningeal artery commences at the
foramen spinosum, and passes anteriorly to the great wing’
of the sphenoid, and posteriorly upon the squama and parietal.
There is also the groove for the internal carotid artery on the
side of the body of the sphenoid, the groove for the superior
longitudinal sinus terminating at the internal occipital pro-
tuberance, those for the lateral sinuses, and others for the
superior and inferior petrosal sinuses on the petrous portion.

The nasal cavities, or the nasal fosse, are placed one on
each side of a median vertical septum. They open in front
by the anterior nasal aperture and behind by the posterior

70 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

nares. They: communicate with the sinuses of the frontal,
ethmoid, sphenoid, and superior maxillary bones. They are
narrow transversely, especially above. The internal wall,
or septum nasi, is formed by the perpendicular plate of the
ethmoid, the vomer, nasal spine of the frontal, crests of the
nasal, rostrum of the sphenoid, crests of the maxillary, and
palate bones. There is an angular deficiency in front, filled
by the septal cartilage, which usually deviates to one side.

Fig. 12

OPENING OF POS.

ETHM. CELLS
OPENING OF SPHE-

NOIDAL SINUS

| 7 OvENING OF MAX-
Til ILLARY SINUS

SPHENO- \\\\ \\\
PALATINE
FORAMEN

The left nasal fossa, viewed from the middle line, showing the three meatuses. (Testut.)

The roof is horizontal in the middle part and sloping in front
and behind. The middle part is formed by the cribriform
plate of the ethmoid, the forepart by the nasal and frontal
bones, the back part by the body of the sphenoid, the ala
of the vomer, and sphenoidal process of the palate. In the
angle formed by the cribriform plate and body of the sphenoid
is the sphenoethmoidal recess; the sphenoidal sinus opens upon
its posterior wall.

The floor is formed by the palate processes of the maxillary
and palate bones; it is smooth and concave transversely, and
shows the orifice of the incisor foramen. The external wall

THE THORAX AS A WHOLE 71

is formed by the nasal, superior maxillary, lacrymal, ethmoid,
inferior turbinate, palate, and internal pterygoid plate of the
sphenoid. The superior and inferior turbinate processes of
the ethmoid and the inferior spongy bone overhang the three
meatuses. The swperior meatus is very short, and placed be-
tween the superior and inferior turbinate processes; into it
open in front the posterior ethmoidal cells, and behind the
sphenopalatine foramen. The middle meatus is above the
inferior spongy bone, and communicates with the anterior
and middle ethmoidal cells, with the maxillary sinus or antrum,
and in front by the infundibulum with the frontal sinus. The
inferior meatus, longer than the others, lies between the inferior
spongy bone and the floor of the cavity; in front is the orifice
of the nasal duct.

The air sinuses communicate with the basal cavities by
narrow orifices; with the exception of the maxillary sinus
(antrum) they are not present at birth. In old age they increase
in size by absorption of neighboring cancellated tissue. The
antrum begins to be formed about the fourth month. The
frontal, ethmoidal, and sphenoidal excavate their respective
bones in childhood, and at puberty undergo a great enlarge-
ment. Their purpose may be for resonance. They have
been sufficiently described with the different bones.

THE THORAX

The Thorax as a Whole

The bony thorax is conical, and flattened from before back-
ward. The short anteroposterior diameter is characteristic
of man, but in the lower mammals and human fetus it is longer
than the transverse diameter. The posterior wall is convex
forward, and a broad furrow on either side, the suleus pulmo-
nalis, is formed by the ribs as they project backward, so that
the weight of the body is more equally distributed around the
column. The anterior wall is convex and at an angle of 20
to 25 degrees with the posterior. A horizontal anteroposterior
diameter from the base of the ensiform is 8 inches (20 em.);
the transverse at the eighth or ninth rib is 11 inches (28 em.);
the vertical anteriorly is 6 inches (15.5 em.), and posteriorly

72 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

is 12 inches (31.5 em.). The upper border of the sternum is
opposite the lower edge of the second dorsal (Henle), and the
lower border opposite the tenth dorsal. The sides slope out
to the ninth rib. The upper aperture is contracted and reni-
form, and sloped downward; the lower is irregular, and its
margin ascends on each side from the tenth rib to the ensiform,
‘forming the subcostal angle. The intercostal spaces are wider
above than below.

The skeleton of the thorax comprises the dorsal vertebrae,
the sternum, ribs, and costal cartilages.

The dorsal vertebrae have been described.

The Sternum

The sternum is an azygos bone in the median line at the
front of the chest. It has attached the clavicles and seven
upper costal cartilages. It originally. consisted of six segments,
and is likened to a sword. The upper segment remains dis-
tinct as the manubrium, or handle; the next four fuse into the
body, or gladiolus (little sword); the sixth portion is the ens?-
form or xtphoid process (sword-like).

The sternum is flattened from before backward, and curved,
with a slight convexity, to the front. It is broad above, narrower
where the two upper segments meet, then broad again, and
narrow at the ensiform.

The manubrium is the thickest part. It presents two sur-
faces, an anterior and a posterior, which are roughly quadri-
lateral. The anterior surface is convex from side to side, and
concave from above downward. It gives attachment, on each
side, to a portion of the pectoralis major aponeurosis, and the
sternal portion of the sternocleidomastoid muscle. The pos-
terior surface is concave and smooth. It gives attachment
to the sternohyoid and sternothyroid muscles of each side.

Superiorly are three deep notches; the middle one is the
semilunar or interclavicular notch; the lateral ones look up,
back, and out for articulation with the clavicles. Below the
lateral notches on either side is a rough triangular surface
for union with the first costal cartilage; next is a sloping con-
cave surface; and at the lower angle a half-notch for the second
rib. The junction of the manubrium with the gladiolus is

THE RIBS 73

always prominent, and serves as a landmark for the second
rib.

The body is longer, narrower, and thinner than the manu-
brium, and tapers toward its lower end. It is marked on its
anterior surface by three slight transverse ridges; otherwise
it is quite flat. This surface gives attachment to a part of the
aponeurosis of the pectoralis major of each side. The posterior
surface is slightly concave and marked by the same lines as
anteriorly, but less distinctly, and gives attachment below to
the triangularis sterni of each side.

Each lateral margin presents four notches and two _half-
notches; they approach each other from above down, being
separated by curved intervals. The half-notch above is for
the second cartilage; the notches for the third, fourth, and
fifth cartilages are opposite the line of junction of the four
segments; the notch for the sixth cartilage and the half-notch
for the seventh belong to the inferior segment. So most of
the cartilages of the true ribs articulate in front at junctions
of segments, analogous to the connection of ribs with the
vertebral column.

The ensiform process (metasternum) projects down between
the cartilages of the seventh rib. It has various forms, is usually
more or less triangular, and may be bent forward, backward,
or laterally, be forked or perforated, and is cartilaginous dur-
ing youth. At its upper angle is a half-notch for the seventh
cartilage.

Its anterior surface has attached the chondroxiphoid liga-
ments. Its posterior surface gives attachment to some fibers
of the diaphragm and triangularis sterni muscles. Its lateral
borders afford attachment to parts of the aponeurosis of the
abdominal muscles. ‘To the apex is inserted the upper end
of the linea alba.

THE RIBS

The ribs (coste) are twelve in number on each side. They
are obliquely placed, running forward and downward. The
obliquity increases from above downward to the ninth rib,
where it reaches its maximum; from there downward it de-
creases.

The first seven pairs, attached be costal cartilages to the

74 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

sternum, are called sternal, true, or vertebrosternal ribs; the
remaining five pairs are asternal or false ribs; each of the upper
three pairs of false ribs has its cartilage attached to the cartilage
above it, vertebrochondral; the last two pairs have no such
attachment, and are floating or vertebral ribs.

Each rib presents three parts—a body, an anterior and a
posterior extremity.

The posterior extremity presents for examination a_ head,
a neck, and a tuberosity. The head is thickened and rough;
it has a superior and an inferior articular facet for articulation
with two vertebrae; the lower is the larger; between them is
a ridge for the attachment of the interarticular ligament.

Fie. 13

Hor anterior costo-transverse ligament.

Facet for body of

upper dorsal vertebra. 4

Ridge for inter-- @7Y¥.

articular ligament.

Facet for body of
lower dorsal vertebra. \

For transverse process of

lower dorsal vertebra.

Ao
Ce

my
r Ted x
% on Wily
< ae 3

Vertebral extremity of a rib; external surface. (Gray.)

Next externally is the flattened neck, about an inch long,
situated in front and above the transverse process of the lower
of the two vertebre the head articulates with. It presents
an anterior and a posterior surface, a superior and an inferior
border. The anterior surface is flat and smooth, the posterior
rough for the attachment of the middle costotransverse liga-
ment. The superior border presents a rough ridge for the
attachment of the anterior costotransverse ligament. The
inferior border is rounded and free. On the lower part of the
posterior aspect of the junction of the neck and shaft is an
eminence, the tuberosity, most prominent in the upper ribs.
It is divided into two parts by an oblique groove. The inner
and lower part is articular for the transverse process of the
lower of the two vertebree, with which the rib is connected;
the outer and upper part is rough for the posterior costo-
transverse ligament.

The body is laterally compressed, presenting two flat sur-

THE PECULIAR RIBS 75

faces, external and internal, and two borders, superior and
inferior. On the eaternal surface, close in front of the tuberosity,
over the most convex portion of the rib, is found an oblique
rough line, directed downward and outward, corresponding
to the outer border of the iliocostalis muscle, marking the
angle. ‘The interval separating the tuberosity and the angle
increases from the second to the tenth rib. The anterior angle
is found near the sternal end of this surface.

The internal surface is smooth, concave, directed slightly
upward behind the angle, and slightly downward in front of it.

The superior border is thick and rounded, and presents an
external and an internal lip, for the attachment of the external
and internal intercostal muscles.

The inferror border presents the subcostal groove, best
marked at the angle disappearing in front. Its external lip
is much the more prominent, and gives attachment to the
external intercostal muscle. ‘The inner or superior lip of this-
groove is rounded and gives attachment to the internal inter-
costal. The groove itself lodges the intercostal vessels and
nerve.

Starting from the upper and inner border of the neck is
a superior costal groove, soon lost on the body.

The anterior extremity is hollowed into a pit for union with -
the costal cartilage. The ribs are curved on three axes—a
vertical one near the angle; also a transverse one at this place,
so that when the anterior part of the rib is horizontal the
posterior will rise up; and a longitudinal one, so that the anterior
part looks up and the posterior part looks down.

The seventh or eighth rib is the longest, after which the
ribs decrease to the twelfth. The first is broadest, and the
twelfth narrowest.

The Peculiar Ribs

The peculiar ribs are first, second, tenth, eleventh, and
twelfth.

The first rib is short and not twisted, yet one of the most
curved. Its surfaces look nearly up and down. The head is
small and has a single articular facet. The neck is slender
and rounded, and the angle coincides with the tuberosity,
which is strong and placed on the outer margin of the rib.
At this point there is a slight bend in the rib, with the con-

76 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

vexity upward. On the upper surface, close in front of the
tuberosity, is a rough impression for the scalenus medius
muscle, and in front of that two smooth depressions with an
intervening ridge; the posterior depression is for the “third
portion” of the subclavian artery, the ridge ending in the
scalene tubercle (Lisfrane’s tubercle) is for the attachment
of the scalenus anticus muscle, and the anterior depression
for the subclavian vein. This surface about its middle also
gives attachment to a part of the serratus magnus. The under
surface is smooth. There is no subcostal groove.

Fia. 14
TUBERCLE

SECOND...
RIB

GROOVE
FOR SUBCLA-
VIAN ARTERY

SCALENE

™& TUBERCLE
GROOVE FOR
UBCLAVIAN VEIN

The first.and second ribs of the right side, viewed from above. (Testut.)

The second rib is not twisted and has no angle (Henle);
it presents near its middle, impressions for the scalenus posticus
and two serrations of the serratus magnus muscles. Its head
presents a double articular facet.

The tenth rib may have but one articular facet.

The eleventh and twelfth ribs are short, have single articular
facets, and only slight elevations to mark the tuberosities
which do not articulate with the transverse process. They
are pointed at their anterior extremities.

The eleventh has a slight subcostal groove; the twelfth has
no angle.

7

‘

THE BONES OF THE UPPER EXTREMITY '¥)

The number of ribs may be thirteen on one or both sides.
The added rib is most often connected with the first lumbar
transverse process, sometimes with the seventh cervical verte-
bra, where it has a double attachment, viz., to the body and
to the transverse process. ‘The twelfth rib variés in length
from 8 inches to less than 1 inch.

The Costal Cartilages

The costal cartilages prolong the ribs to the sternum. Their
breadth diminishes from the first to the last; they become
narrow toward their sternal extremities; their length increases
to the seventh; the first descends a little, the second is hori-
zontal, the others, except the last two, ascend after following
the direction of the rib for a short distance. Their external
extremities are convex, and planted into the osseous tissue
of corresponding ribs. The inner extremity of the first is
united directly to the sternum without articular cavity; the
succeeding six have rounded extremities for the sternal notches.
Each cartilage of the first three false ribs is united to the lower
border of the one above it. The fifth, sixth, seventh, and
eighth cartilages articulate with each other; the eleventh

and twelfth are pointed and unattached.

They give partial attachment to the diaphragm, internal
abdominal, oblique, transversalis, rectus, triangularis sterni,
internal intercostals, pectoralis major, subclavian, and sterno-
thyroid muscles.

- The eighth may articulate with the sternum. The seventh
may meet its fellow of the other side in front of the ensiform.
There may be no articulation between the fifth and sixth;
theresmay be one between the eighth and ninth.

THE BONES OF THE UPPER EXTREMITY

Shoulder | pelea \, forming shoulder girdle.

Arm (brachium), humerus.

Upper limb } Forearm (antebrachium), radius and ulna.
carpus.

Hand (manus) 4j metacarpus.
phalanges.

78 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

THE BONES OF THE SHOULDER GIRDLE

The Clavicle

The clavicle (key) passes out, back, and ‘slightly upward
from the summit of the sternum to the acromion, and con-
nects the upper limb to the trunk. It is curved like the letter
f. The inner curve is convex forward, and occupies two-
thirds of the bone; this part is prismatic. The outer third
of the bone is concave in front, and is flattened from above
down.

The superior surfaces of these two portions are continuous;
the inferior surfaces are continuous; the anterior border of
the outer portion runs into the anterior surface of the inner;
and the posterior border of the outer is continuous with the
posterior surface of the inner.

The superior surface is broad externally and largely sub-
cutaneous; at its centre it may present a canal for the supra-
clavicular nerve; the sternocleidomastoid is attached to the
inner part. The anterior surface is reduced to a rough border
on the outer third, where it gives attachment to the deltoid,
and may present a deltoid tubercle. The pectoralis major is
attached to the inner half.

The posterror surface is a border externally to one-third
the extent of the bone, and gives attachment to the trapezius.
In the middle of this surface is the orifice of a medullary canal
directed outward. (In bones having but one secondary centre
the medullary artery runs from it.) Internally close to the
sternal end this surface gives attachment to a part of the
sternohyoid muscle. ¢

The inferior surface is narrow at its sternal end, widening
out to the full width of the bone in its outer third. It shows
internally a rough impression or costal tuberosity about 1 inch
long, for the rhomboid ligament; internal to it is a small facet
for articulation with the cartilage of the first rib; external
to it, a groove passing beyond the middle third for the sub-
clavius muscle; the groove may show a longitudinal ridge for
an intermuscular septum. On the posterior border, at the
junction of the outer and middle thirds, is the conoid tubercle

THE SCAPULA 79

(scapular tuberosity), and passing out and forward from it
the trapezoid line.

The sternal end is thick and projects in an angle downward
and backward, its triangular concavoconvex surface looking
a little downward and forward. The scapular end is so bevelled
as to rest upon the acromion, the small articular surface look-
ing down and out; this end is normally a little higher than
the acromion on which it rests.

The Scapula

The scapula is a large triangular flat bone, situated at the
posterior and lateral aspect of the chest, between the second
and seventh ribs of the seventh interspace. Its posterior border
is about 1 inch from and parallel with the vertebral spines.
It is attached to the trunk by the clavicle and by muscles,
and from it is suspended the humerus.

The bone consists of a large triangular blade or body, and
two processes, the coracoid and spine, and presents for exami-
nation two surfaces, three borders, and three angles. The
anterior surface, or venter, looks forward, downward, and inward,
and presents the subscapular fossa, marked by three or four
converging oblique lines, giving attachment to tendinous
intersections of the subscapular muscle. ‘The deepest part
of the fossa is the subscapular angle, where the bone seems
bent on itself, so that the thickest part of the muscle is per-
pendicular to the plane of the glenoid cavity, and can act
most advantageously. Separated from this fossa are two
flat surfaces, one at the upper angle and one at the lower;
with the line connecting them close to the vertebral border
they give attachment to the serratus magnus muscle.

The posterior surface, or dorsum, is divided by the spine
into two unequal fossa, the supraspinous and infraspinous.
The supraspinous is less than half the size of the infraspinous
fossa. It is smooth, concave, and broader at its vertebral
than at its humeral end, and gives origin by its inner two-
thirds to the supraspinatus muscle.

The lower fossa is marked near the centre by a convexity
corresponding to the concavity of the venter; on either side
of this is a groove, the external one being deep and bounded
by the axillary border. Near the inner border are short lines

80 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

for intermuscular septa of the infraspinatus muscle, which

rises from the inner two-thirds and covers the outer third.

Along the outer part of this surface is a ridge passing down
and back to the inner border, about 1 inch above the inferior
angle; it gives attachment to the aponeurosis between the
infraspinatus and teres muscles. On the upper third of the
narrow surface between this line and the axillary border is
a groove for the dorsalis scapule vessels; the middle third and

part of the upper give attachment to the teres minor. Below —

this, including the inferior angle, is a raised surface for the
teres major, over which the latissimus dorsi glides or attaches
a small fasciculus. An oblique line separates the origins of the
two teres muscles.

The spine of the scapula is a triangular plate projecting
back and up from the dorsum. Beginning near the upper
fourth of the vertebral border, it passes out, across the dorsum
to the middle of the neck of the scapula, and turns forward
into the acromion process. The upper and lower surfaces
are concave and form parts of the two dorsal fosse. It has two
unattached borders,: a posterior subcutaneous one and an
external axillary one. The former rises from the vertebral
border by a triangular surface, over which a tendon of the
trapezius glides as it passes to its insertion into a rough tubercle
beyond. The rest of this border is rough and serpentine, and
gives attachment by a superior lip to the trapezius, by an infe-
rior lip to the deltoid. The external border is short, smooth,
and concave, enclosing the great scapular notch.

The acromion process projects out and forward over the glen-
oid fossa; it is compressed from above down; its superior surface
is rough, subcutaneous, and continuous with the prominent
border of the spine. Anteriorly, on its inner border, is an oval
articular facet for the clavicle; to this border is attached the
trapezius, to the outer border the deltoid, marked by three or
four tubercles for tendinous septa. This outer border terminates
posteriorly in the acromial angle. The coracoacromial liga-
ment is attached to the apex of the acromion.

The coracoid process rises at first almost vertically from the
upper border of the head, compressed from before backward;
it then bends at a right angle forward and outward, and is
compressed from above downward. Superiorly, toward its
base, is the origin of the conoid ligament, and the trapezoid

THE SCAPULA 81

rises from an oblique line running forward and outward from
attachment of the conoid ligament on the superior surface.
The coracoacromial ligament is attached to the outer border,
the conjoined tendon of the coracobrachialis and biceps to its
apex, and the pectoralis minor to its inner border and adjacent
part of the superior surface. The tip of the coracoid is about
one and one-half inches distant from the apex of the acromion.

Pies 15

SUPERIOR ANGLE

The right scapula, dorsal view. (Testut.)

The eaternal angle of the scapula is the thickest part of the
bone; it is called the head, supported on a neck. The head
bears the glenoid cavity; this is slightly concave, looks outward,
forward, and slightly upward. It is pyriform, with its narrow
end above, and measures 12 inches by 1+ inches (40 mm. by
30 mm.). Above it is a supraglenoid tubercle for the long head

6 .

82 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

of the biceps. The “anatomical neck” is the part just behind
the head.

The superior angle of the scapula is thin and rounded, and
gives attachment to some fibers of the levator anguli scapule.

The inferior angle is thick and rough posteriorly for the teres
major attachment, sometimes the latissimus dorsi.

The superior border is shortest, and extends from the superior
angle down to the coracoid, at the base of which is the supra-
scapular or coracoscapular notch.

The axillary border is the thickest. Beneath the glenoid
fossa is a rough tubercle or ridge, infraglenoid, over an inch
long, for the long head of the triceps. On the ventral aspect of
this border is a longitudinal groove, from the lower part
of which the subscapular muscle rises in part.

The vertebral border is the longest, and gives attachment
above the triangular surface at the apex of the spine to the
levator anguli muscle, opposite the triangular surface to the
rhomboideus minor, and below this to the rhomboideus major.

THE BONE OF THE ARM

The Humerus

The arm bone extends from the shoulder to the elbow. It
is divisible into an upper extremity, including head, neck,
great and small tuberosities, a shaft, and inferior extremity,
which includes condyles, epicondyles, and articular surface.
The head forms one-third of a sphere, but the margin is not
a true circle. The head is directed up, in, and a little back-
ward, and makes an angle of 140 degrees with the shaft. The
“anatomical neck” is the slight constriction at the circum-
ference of the articular surface; the “surgical neck” is below
the tuberosities.

The great tuberosity is a thick projection starting up from
the external surface of the shaft. It is marked above by three
facets, the upper for the supraspinatus tendon, the next for
the infraspinatus, and the lowest for the teres minor, which
also is attached to the shaft to the extent of 1 inch. Internally
separated from this tuberosity by the bicrpital groove (inter-
tubercular sulcus) 1 is the small tuberosity, looking forward and
inward and giving attachment to the subscapularis.

a?

pris rey be Ts ee Seo pete

THE HUMERUS 83

The shaft is thick and cylindrical above, expanded transversely
and three-sided below. It is divided into external, internal, and
posterior surfaces by anterior and lateral borders. Superiorly
is the bicipital groove lodging the long tendon of the biceps
and a branch of the anterior circumflex artery. This groove,
descending, is bounded by rough margins, the external or pec-
toral ridge for the pectoralis major muscle, and the internal
for the latissimus dorsi and teres major muscles. These muscular
attachments end at the junction of the upper fourth with the
lower three-fourths.

The anterior border is the pectoral ridge continued to the
coronoid depression below. It becomes rounded and smooth
below, and gives attachment to the brachialis anticus muscle.

The inner border is the inner bicipital ridge continued to
the inner condyle, called below the internal supracondylar
ridge. About the centre of this border is a rough linear mark
for the coracobrachialis muscle, and just below it the orifice
of the medullary canal directed downward.

The eaternal border runs from the back part of the great
tuberosity to the external condyle. Its centre is traversed
by a broad spiral groove, which is limited above by the deltoid
eminence and below by the eaternal supracondylar ridge. 'This
ridge gives origin by its upper two-thirds to the supinator
longus muscle; hence it is called the supinator ridge, which
is very large in burrowing animals; its lower third attaches
the extensor carpi radialis longior. The posterior lip of either
supracondylar ridge is for the triceps, and a middle portion
for intermuscular septa. The eaternal surface presents near
its middle the deltoid eminence; above this it is smooth and
rounded; below it, it is smooth and looks outward and forward,
giving attachment to a part of the brachialis anticus.

The internal surface is narrow above, and forms the bicipital
groove; near its centre is the insertion of the coracobrachialis.
Below this level it is smooth, looks inward and forward, and
gives attachment to parts of the brachialis anticus.

The posterior surface is twisted, so that its upper part is
directed a little inward, its lower part backward and outward.
It is nearly all covered by the external and internal heads of
the triceps, which are separated by the spiral groove running
down and out. At the upper part of this groove is generally
a second medullary foramen for a branch of the superior pro-
funda artery.

84 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

The inferior extremity is flattened from before backward
and curved slightly forward. The two condyles include the

Fie. 16

SMALL
TUBEROSITY

SURGICAL
NECK

MUSCULO-
SPIRAL GROOVE

_. ¥adHos BON:

zt
Po
x
EXTERNAL INTERNAL
CONDYLE CONDYLE

The right humerus, front view. (Testut.)

THE HUMERUS 85

articular surface, separated by a rounded ridge; the inner
condyle is five-sixths articular. The prominent tuberosities
situated on either condyle are the epicondyles, developed from
separate centres. The internal epicondyle is the more promi-
_ nent one, is inclined backward, and forms posteriorly a shallow
groove for the ulnar nerve. It gives attachment to the pro-
_nator radii teres and the common tendon of the superficial
pronatoflexor muscles of the forearm.

The eaternal condyle presents (1) the epicondyle, which
gives origin to some of the supinatoextensor muscles of the
forearm; (2) below and internal to this on the condyle a small
impression for the anconeus; and (3) a pit for the external
lateral ligament.

The inferior articular surface is divided into two parts:
The external part, rounded and directed forward, is the capt-
tellum for articulation with the radius; it does not extend at
all on the posterior surface. Internal to it is a groove for the
inner margin of the head of the radius. The internal portion,
or trochlea, articulates with the ulna, and extends upon the
anterior and the posterior surface of the bone; the external ©
border is rounded and corresponds to the interval between
the radius and ulna. The internal border is thick and promi-
nent. Anteriorly these margins are inclined down and inward,
posteriorly up and outward, so that the groove is obliquely
inclined from without inward, and if continued would form
the thread of a screw. The external part of the trochlea is
the segment of a sphere, the internal part the segment of a
truncated cone with base internal; at the junction of the cone
and sphere is the groove.

Above the trochlea posteriorly is the olecranon fossa, above
it anteriorly the coronoid fossa; the thin plate between them
may be perforated by the supratrochlear foramen. This occurs
more often in the lower races of man. Above the capitellum
is the radial fossa for the head of the radius in flexion.

The average length of the adult male humerus is 13 inches;
female, 12 inches. It is nearly one-fifth the height of the
individual. The right humerus with the radius is usually
x ae inch longer than the left; but there is no difference at
birth.

The shaft of the humerus is twisted through about 135
degrees. The twist is seen at the spiral groove, “groove of

— Ae ee

|

86 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM
torsion,’ which does not exist in the fetus; this allows the
hand to serve the purposes of the head and mouth. A small
hooked supracondylar process is sometimes found about two
inches above the inner epicondyle.

THE BONES OF THE FOREARM

The Ulna

This is the internal of the two bones of the forearm. It
articulates with the humerus, radius, and the triangular articulo-
cartilage at the wrist. It presents for examination a shaft and
two extremities.

The upper extremity presents two processes and two articular
concavities.

The olecranon process forms the uppermost part of the ulna.
It terminates superiorly in front in a beak which overhangs
the great sigmoid cavity; behind this is a rectangular tuberosity,
forming the point of the elbow. It has superiorly a quadri- .
lateral surface, transversely grooved in front for attachment
of the posterior ligament of the elbow; behind this it gives
attachment to the triceps. The posterior surface of the olec-
ranon is triangular and subcutaneous, covered by a bursa,
and continuous with the posterior border of the ulna.

The lateral surfaces show anteriorly continuations of the
groove just mentioned, the inner for the posterior portion of
the internal lateral and the external for part of the posterior
ligament of the elbow. Internally there is also attached a
portion of the flexor carpi ulnaris; externally the anconeus.
The anterior surface is smooth, curved forward above, and
forms the upper and part of the greater sigmoid cavity. The
inferior surface, or base, is attached to the shaft.

The coronoid process is a rough triangular eminence pro-
jecting forward from the anterior aspect of the ulna just below
the olecranon. Its base is large and firmly united to the shaft.
Its upper surface is smooth, concave, forming the inferior
portion of the greater sigmoid cavity and the lowest part of ©
the back of that cavity. Its apex is bluntly pointed, and
curved slightly upward. The under surface is rough, con-
cave, looking downward and outward. At the junction of

THE ULNA 87

this surface with the shaft and extending a short distance
down on the shaft is a rough eminence, the tubercle of the

HEAD OF
RADIUS

TUBERCLE
OF RADIUS

POSTERIOR
BORDER

POSTERIOR
BORDER

EXTERNAL
SURFACE

STYLOID Wy Sao STYLOID
PROCESS Sag PROCESS

The bones of the right forearm, rear view. (Testut.)
ulna, for attachment of the upper end of the oblique ligament

and part of the brachialis anticus; the main part of this muscle
is attached to the inner part of the junction of the coronoid

88 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

and shaft. Its eaternal surface presents the lesser sigmoid
cavity, and just below it a small area giving attachment to
a part of the supinator brevis. The inner surface is slightly
concave, and bounded in front by a prominent margin, termi-
nating above in a rounded eminence. To the eminence one
head of the flexor sublimis digitorum is attached, to the ridge
the deep head of the pronator radii teres, and on the surface
itself one portion of the flexor profundus digitorum finds
origin. Often a fasciculus of the flexor longus pollicis arises
from the lower part of this surface.

Fie. 18

roto Anterior Border -----------

-----Anterior Surface -----

Interosseous
Border

External _ ee Ns ate Una |___tnternar
Surface . Surface

! |

| '

' |

! |

.---- Posterior Surface -----

Showing a transverse section of the radius and ulna and indicating their borders
and surfaces.

The great sigmoid cavity, articulating with the trochlea,
looks upward and forward, and is bounded above by the olec-
ranon and below by the coronoid processes; it is concave from
above down, and is traversed by a longitudinal ridge, which
is a half-circle.

A slight constriction is seen across the middle of the cavity.
The part external to the ridge is broad and convex above the
constriction, concave in its other subdivisions.

Continuous with this cavity is the small sigmoid cavity on
the outer side of the base of the coronoid; it is concave from

o

THE ULNA 89

before backward, with its long axis in the same direction,
for the head of the radius.

The shaft, or body, tapers from above, is three-sided in its
upper three-fourths, slender and cylindrical in its lower fourth.
The upper three-fourths is convex backward; it is also convex
externally above and internally below. The anterior border
passes from the inner edge of the coronoid to the front of
the styloid; it is thick and rounded, and gives attachment to
the flexor profundus digitorum, and in the lower fourth to the
pronator quadratus.

The posterior border begins below the olecranon, and runs
with a sinuous curve to the back of the styloid. It is ill defined
below and subcutaneous throughout, and affords attachment
to an aponeurosis common to three muscles—the flexor carpi
ulnaris, extensor carpi ulnaris, and flexor profundus. The
external or interosseous border is a sharp edge in the middle
three-fifths of the shaft. Below it is faintly marked. The
upper fifth is continued by two lines passing to the extremities
of the small sigmoid notch; the posterior line is the prominent
supinator ridge, for the supinator brevis muscle.

The anterior surface is concave above, and gives origin to
the flexor profundus digitorum; the lower third is marked
off by the oblique pronator ridge, directed downward and up-
ward, limiting above the origin of the pronator quadratus.
Above the middle is a medullary foramen directed upward.

The internal surface is smooth, and gives attachment to
the flexor profundus digitorum muscle; it is subcutaneous
in the lower third.

The posterior surface looks outward and backward; an oblique
line descending from the supinator ridge to the posterior border
at the junction of its upper and middle thirds marks .off a
triangular area for the anconeus muscle. The ridge itself
gives attachment to the supinator brevis. Below this is a
longitudinal ridge dividing the surface into a smooth inner
portion covered by the extensor carpi ulnaris, and an outer
part giving attachment from above downward to the extensor
ossis metacarpi pollicis, extensor secundi internodii pollicis,
or extensor longus pollicis, and extensor indicis.

The inferior extremity presents a rounded head; from its
inner and back part the styloid process projects downward,
giving attachment to the internal lateral ligament and to the

90 OSTEOLOGY, OR ANATOMY OF OSSEHOUS SYSTEM

triangular fibrocartilage. Posteriorly between the head and
styloid process is a groove for the tendon of the extensor carpi
ulnaris.

The head has two articular surfaces—an inferior one, upon
which the triangular fibrocartilage plays, and an outer narrow
convex one, for the sigmoid cavity of the radius. With the
hand supine the styloid process projects at the inner and back
part of the wrist; if pronated, the outer and forepart of the
ulnar head is prominent between the tendons of the extensor
carpi ulnaris and extensor minimi digiti.

The Radius

The radius is the outer and smaller of the two bones of
the forearm. It articulates with the humerus, ulna, scaphoid,
and semilunar bones, and presents for examination a shaft
and two extremities.

The superior extremity, or head (eminentia capitata), is
disk-shaped. On its summit is a shallow depression for the
capitellum of the humerus. Its circumference is convex,
broadest internally, where it rotates in the small sigmoid cavity
of the ulna within the orbicular ligament. The head is sup-
ported by a neck, round and smooth, which presents behind
a perpendicular ridge for part of the insertion of the supinator
brevis.

The shaft is larger below than above, slightly curved, and
convex outward and backward. Anterointernally below the
neck is the bicipital tuberosity, rough posteriorly for the inser-
tion of the biceps, and smooth in front for a bursa. Below
this tuberosity the shaft has three surfaces and three borders.

The anterior border extends from the tuberosity to the base
of the styloid; its upper part runs downward and outward
to the middle of the bone, being called the anterior oblique
line, and gives attachment to the supinator brevis, flexor
longus pollicis, and flexor sublimis. The pronator radii teres
is attached at the middle of the border, which from this point
descends vertically.

The posterior border runs from the back of the neck to the
posterior part of the base of the styloid. It is well marked
only in its middle third.

The internal or interosseous border becomes prominent below,

THE RADIUS 91

and at its lower part divides into two ridges, which include
the margins of the sigmoid cavity, analogous to the division
of a like border of the ulna.

The anterior surface is grooved longitudinally for the flexor
longus pollicis muscle; at the lower end to the extent of about
a quarter of the surface is an impression for the pronator
quadratus. A medullary foramen is above the middle of this
surface passing upward.

The posterior surface shows at the junction of the upper
and middle thirds the posterior oblique line, running downward
and outward to the posterior margin; below this, the entire
width of the surface, is attached the extensor ossis metacarpi
pollicis, and below that, by a long, narrow impression con-
tiguous to the interosseous margin, the extensor primi internodii
pollicis (extensor brevis pollicis).

The eaternal surface is convex, and marked near the middle
by an impression for the pronator radii teres; above this, on
the area between the anterior and posterior oblique lines,
is inserted the supinator brevis.

The lower extremity of the radius, broad and quadrilateral,
presents a carpal articular surface and an ulnar articular
surface. The former is divided by a line into a quadrilateral
inner part for the semilunar, and a triangular outer part for
the scaphoid. The articular surface for the ulna or sigmoid
cavity is at right angles to the inferior surface, and concave
from before backward. To the smooth border between these
two articular surfaces is attached the base of the triangular
fibrocartilage. Externally the styloid process projects downward.
Anteriorly a transverse ridge forms the lowest limit of the
pronator quadratus impression, which is continued into a
vertical ridge external to that impression; between this ridge
and the scaphoid facet is a triangular area for a strong band
of the anterior ligament. ‘The external and posterior aspects
are marked by the following grooves from without inward;
a flat groove for the extensor ossis metacarpi pollicis and
extensor primi internodii or extensor brevis pollicis (next
descends the styloid process); a broad groove, subdivided
by a slight ridge, for the extensor carpi radialis longior and
brevior; an oblique narrow groove, directed downward. and
outward, bounded externally by a tubercle,-for the extensor

secundi internodii pollicis (extensor longus pollicis); a broad

92 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

groove for the extensor indicis, extensor communis, and exten-
sor minimi digiti. Just above the first groove is an impression
for the supinator longus.

THE BONES OF THE HAND

The skeleton of the hand consists of three segments—wrist
bones, bones of the palm (metacarpal), and bones of the
fingers (phalanges).

The carpus, or wrist bones, are composed of eight short
bones arranged in two rows: the upper row, from the radial to
the ulnar side, comprises the scaphoid, lunar (semilunar),
pyramidal (cuneiform), and pisiform; in the inferior row are
the trapezium, trapezoid, os magnum, and unciform.

THe ARTICULATIONS OF THE CARPAL BONES

| Superior. | External. Inferior. | Internal. “Hor pao ee
es es
Scaphoid Radius | Free Trapezium | Os magnum| Free | Free 5
) trapezoid | semilunar
Semilunar Radius Seaphoid | Os magnum | Cuneiform | Free Free 5
. unciform |
Cuneiform Triangular) Semilunar | Unciform Free | Pisi- Free 3
fib. cart. | | | form
Pisiform Free | Free Free Free | Free pris 1
; orm
Trapezium Scaphoid __ Free First meta- | Trapezoid | Free Free 4
) carpal second met-.
acarpal
Trapezoid | Seaphoid | Trapezium| Second NaF Os magnum) Free’ Free
carpa |
Os magnum! Scaphoid Trapezoid |Second, third,, Unciform | Free Free
_ semilunar | and fourth .
metacarpals
Unciform Semilunar Os mag- Third and | Cuneiform | Free Free
. num ‘fourth meta-|

| carpals | | |

The metacarpus, or bones of the palm, support the fingers,
and consist of five long, slightly divergent bones, which articu-
late with the carpus as follows:

The first metacarpal articulates at its base with:one bone.

The second metacarpal articulates at its base with four bones.

The third metacarpal articulates at its base with three bones.

The fourth metacarpal articulates at its base with four bones.

The fifth metacarpal articulates at its base with two bones.

THE ILIUM 93

It is interesting that the corresponding metatarsals articu-
late with exactly the same number of bones of the tarsus.

THE BONES OF THE LOWER EXTREMITY

The lower limb consists of the haunch, or hip, thigh, leg,
and foot. In the haunch is the hip bone; in the thigh, the
femur; in the leg, the tibia and fibula; at the knee, a large
sesamoid bone, the patella; in the foot, the tarsus, metatarsus,
and phalanges.

THE BONES OF THE PELVIS (PELVIC GIRDLE)

The Hip Bones (Ossa Innominata)

The hip or innominate bone (os core), with its fellow, the
sacrum, and coccyx form the pelvis. This bone is constricted
in the middle and expanded above and below. In early life
it is made up of three bones, the ilium, pubes, and ischium,
and for the sake of description the adult bone is said to be
made up of these portions.

The Ilium

The aliwm (lium, flank) is the superior expanded portion, and
forms less than two-fifths of the acetabulum. This portion is
limited anteriorly and posteriorly by margins which diverge at
right angles from each other, and superiorly by the arched crest
of the cium. In front the crest is concave inward, and behind
it is concave outward. It is much wider near its extremities
than in its middle, and there is often a marked external projec-
tion in its anterior third. On the crest are external and internal
lips and a median ridge.

The anterior extremity projects as the anterior supervor spine;
below it is a concavity, the lesser lac notch, and below that
the anterior inferior spine. Behind, the projecting extremity
of the crest is called the posterior superior spine, separated by
a small notch from the posterior inferior spine, below which is
the great sciatic (iliosciatic) notch.

94 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

To the external lip, from before backward, are attached the
tensor vagine femoris, external abdominal oblique, latissimus
dorsi, and gluteus maximus; and throughout its entire length
the fascia lata. To the internal lip, from before backward,
are attached the transversalis abdominalis, quadratus lum-

Fia. 19

POSTERIOR SUPE-
RIOR SPINE ANTERIOR SUPE-

RIOR SPINE

Ur

ANTERIOR IN-

POSTERIOR IN--®% FERIOR SPINE

FERIOR SPINE

Z
i hi ACETABULU

The right hip bone, outer surface. (Testut.)

7

borum, and erector spine, and to that part of this lip corre-
sponding to the internal iliac fossa the iliacus and iliac fascia.
To the middle ridge is attached the internal abdominal oblique
muscle. The anterior-superior spine has attached externally
the tensor vaginee femoris, in front the sartorius, and internally

THE OS PUBIS 95

Poupart’s ligament. The straight head of the rectus femoris
arises from the anterior-inferior spine of the ilium.

The external surface, or dorsum ilit, presents three curved
gluteal lines. The posterior or swpertor one commences 2 inches
in front of the posterior superior spine, and curves down and
forward to the back part of the iliosciatic notch. The middle
gluteal line begins in front about 14 inches behind the anterior
superior spine, and arches back and down to the upper part
of the notch. The inferior gluteal line, less strongly marked,
commences just above the anterior inferior spine, and passes
back to the forepart of the notch. Behind the posterior line
is a semilunar surface, rough above for the gluteus maximus;
the sickle-shaped space between the posterior and middle
lines and iliac crest is occupied by the gluteus medius; the
gluteus minimus is between the middle and inferior lines.
Just above the acetabulum is an elongated mark for the re-
flected head of the rectus femoris. ?

The internal surface is divided into two unequal parts. The
anterosuperior part is much the larger, and is called the diac
fossa, or venter ilii. It is concave and smooth, giving attach-
ment to the- iliacus muscle, excepting at its anteroinferior
portion. It is separated from ‘the true pelvis by the iliac portion
of the iliopectineal.

To the inner side of the anterior inferior spine is a shallow
groove, the greater iliac notch, which lodges the iliopsoas muscle
as it passes under Poupart’s ligament; the inner boundary of
the groove is the iliopectineal eminence, making the junction of
the pubis and ilium. The posteroinferior part is again divided,
presenting from below upward (1) a smooth curved surface
in the true pelvis, giving attachment in part to a portion of
the obturator internus, separated from the iliac fossa by the
iliac portion of the iliopectineal line; (2) the auricular surface,
for articulation with the sacrum; (3) depressions for the pos-
terior sacroiliac ligament; (4) a rough surface giving origin
to the erector and multifidus spine muscles.

The Os Pubis

The os pubis forms the anterior wall of the pelvis, and bounds
the thyroid foramen above and partly in front. It consists
of a body and two rami. At the inner extremity of the body

96 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

facing inward is a long oval surface marked by transverse
ridges or nipple-like processes for articulation with the opposite
bone; the junction is the symphysis pubis. The part passing
down and out from the symphysis is the descending ramus;
the upper part is the superior or ascending ramus; and the
flat portion between the rami is the body. The pelvic surface
of the body is smooth, the anterior surface rough. Anteriorly
at the upper extremity of the symphysis is the angle; extending
out from this on the superior border is the crest, terminating
in the spine. The descending ramus is thin and flat, and joins
that of the ischium at a point a little more than half-way from
the body of the pelvis to the tuberosity of the ischium. The
superior ramus becomes prismatic, ending externally at the
acetabulum, of which it forms about one-fifth; its superior
border is the pubic portion of the iliopectineal line, running
from the spine of the pubis to the internal aspect of the ilio-
pectineal eminence. The triangular surface in front of this
line gives origin to the pectineus muscle; below is the obturator
crest, extending from the pubic spine to the margin of the
acetabulum. Behind the outer part of this crest on the inferior
surface of the ramus is the obturator groove, directed from behind
forward and inward.

The pubic crest gives origin to part of the conjoined tendon,
the pyramidalis and rectus abdominis. To the pubic spine
are inserted Poupart’s ligament and the outer pillar of the
external abdominal ring. From the front of the pubis, in the
angle between the crest and the symphysis, arises the adductor
longus muscle, and below this the adductor brevis and part
of the adductor magnus. Internal to these the gracilis is
attached, and external the obturator externus. Posteriorly
the pubis gives attachment to the obturator internus; above
this is sometimes a faint line passing from the upper margin
of the obturator foramen to the lower end of the symphysis;
the levator ani muscle is attached to it, and the obturator and

rectovesical fascize.

The Ischium

The ischium forms the lower and back part of the hip bone,
bounds the thyroid foramen below, and forms over two-fifths
of the‘acetabulum. It presents a body, and below this a tuber-

THE ISCHIUM 97

osity continued forward into the ramus. The body has three
surfaces, external, internal, and posterior, and three borders.

The external surface helps form the acetabulum; here it
is smooth and concave; below this and above the tuberosity
is a horizontal groove for the tendon of the obturator externus
muscle.

The internal surface is roughly quadrilateral, slightly con-
cave and smooth, and forms part of the wall of the true pelvis.
It is limited above by the ridge marking the junction of the
ischium and ilium, in front by the junction with the pubis
and by the obturator foramen, and behind by the anterior
margin of the great sciatic notch. Below it is continuous with
the tuberosity. It gives attachment to a part of the obturator
internus muscle. ; |

The posterior surface is quadrilateral, getting narrow below,
and continuous with the tuberosity. It is limited in front by
the margin of the acetabulum, behind by the posterior margin
of the bone; above it is continuous with the ilium, below with
the tuber ischii. Below it presents a part of the groove for
the obturator externus, and supports the pyriformis, the two
gemelii, and the obturator internus.

On the posterior border, a little below its middle, is the
spine, projecting back and in, and forming the inferior limit
of the iliosciatic notch. Internally it gives attachment to the
levator ani and coccygeus muscle, and externally to the gemellus
superior. The small sciatic notch is between the spine and
tuberosity of the ischium.

The external border is that part of the acetabular rim formed
by the ischium. The internal border is thin, and forms the
outer boundary of the obturator foramen.

The tuberosity presents three surfaces—external, internal,
and posteroinferior.

The external surface is continuous above with the groove
for the tendon of the obturator externus and below with the
ramus. In front it is limited by the posterior margin of the
obturator foramen, and externally by a prominent margin
which separates it from the posteroinferior surface. Close
in front of this margin a portion of the quadratus femoris is
attached, while in front of it is a part of the obturator externus,
and below is the adductor magnus.

The internal surface is smooth and slightly concave. It

7

98 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

is limited in front by the margin of the obturator foramen;
behind and below by a sharp ridge for the attachment of the
falciform prolongation of the great sciatic ligament.

The posteroinferior surface of the tuberosity presents two
lips and an intermediate space. The external lip gives attach-
ment to the quadratus femoris and adductor magnus; the
inner lip to the falciform portion of the great sacrosciatic
ligament. The intermediate space is divided into two por-
tions; the anterior part attaches the adductor magnus externally
and the great sacrosciatic ligament internally; the posterior
part has two facets, an upper and outer for the semimembra-
nosus, a lower and inner for the biceps and semitendinosus.

The ramus joins the descending ramus of the pubis at the
inner side of the thyroid foramen. Its outer surface is rough,
and gives attachment to the obturator externus, adductor
magnus, and gracilis. The crus penis and transversus peronei
are attached to the inner border. :

The acetabulum, or cotyloid cavity, is cup-shaped, and looks
out, down, and forward. It is formed by portions of the ilium,
pubis, and ischium. Scant two-fifths is ilium, a little more
than two-fifths is ischium, and a little more than one-fifth pubis.
It is nearly surrounded by a prominent rim which presents
three depressions—a slight one anteriorly and _ posteriorly,
and the cotyloid notch below. In the lateral and upper parts
of the cavity is a broad horseshoe-shaped articular surface.

The central part. of the cup and the notch are depressed
(fossa acetabuli), and contain fat and the interarticular liga-
ment (ligamentum teres or round ligament). This non-articular
surface belongs mostly to the ischium.

The thyroid or obturator foramen (foramen ovale) is internal
to and below the acetabulum. It is nearly oval in the male,
more triangular in the female. It is closed by fibrous mem-
branes, except in the region of the obturator groove in its upper
margin.

The Pelvis as a Whole

The pelvis (basin) is composed of four bones: two ossa
innominata, the sacrum, and coccyx. It is divided into two
parts by a plane passing through the sacral promontory, ilio-
pectineal lines, and upper border of the symphysis. This
circle is the inlet or brim of the true pelvis; the space above it

THE FEMUR 99)

really belongs to the abdomen, but is called the false or upper
pelvis. The pelvic outlet presents three large prominences,
the cocecyx and the tuberosities of the ischia. Beneath the
symphysis and between the puboischiatic rami is the subpubic
arch; behind the ischial tuberosities are the sacrosciatic notches.

Position of the Pelvis—In the erect attitude, with the
heels together and toes turned out, the plane of the brim forms
an angle of 60 degrees with the horizontal, that of the outlet
16 degrees. ‘The base of the sacrum is about 33 inches above
the upper margin of the symphysis, and the tip of the coccyx
about 4 inch above the apex of the subpubic arch. The sacrum
looks down and forward, and is the inverted keystone of an
arch, as its pelvic surface is broader than the dorsal; it is held
in place chiefly by ligaments and by a slight bony projection
into the iliae articular surface.

Differences in the Pelvis According to Sex.—In the female
the bones are more slender and the muscular impressions less
marked; the height is less, breadth and capacity greater; but
the false pelvis is relatively narrower than in the male. The
sacrum is wider and flatter, less prominent; the subpubic arch
is wider, about 90 degrees (male is 75 degrees); and the space
between the ischial tuberosities is greater. The thyroid fora-
men is broader and more triangular in the female, nearly oval
_ in the male.

The sacrum and coccyx have been described as the false
vertebrae (page 28).

THE BONE OF THE THIGH,

The Femur

The femur (thigh bone) is the largest, longest, and strongest
bone of the skeleton. In the erect position it inclines inward
and slightly backward. It is divisible into a superior extremity,
including head, neck, and two trochanters; shaft; and inferior
extremity, expanded into external and internal condyles and
epicondyles.

The neck extends upward, inward, and slightly forward,
iaice set upon the shaft at an angle of 125 degrees. It
is compressed from before backward, is broad at its base,

100 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

becomes rounded at its summit, and enlarged as it joins the
head. It is shorter above and in front than below and behind.
Posteriorly it usually shows a shallow groove for the obturator
externus tendon. Its junction with the shaft behind is marked
by the posterior intertrochanteric line. The capsule of the
hip-joint is attached to the neck about half an inch internal
to and above this line.

The head is joined to the shaft by the neck. It forms more
than a half-sphere, and articulates with the acetabulum. A
little below and behind the centre of its surface is a depres-
sion (fossa capitis), the forepart of which gives attachment
to the interarticular ligament (ligamentum teres) of the joint.
In this hollow are one or two vascular foramina.

The great trochanter (to turn) is a thick process prolonged
upward in a line with the external surface of the shaft to a
level about 5 or 3 inch below the head. In front it is marked
by a broad depression for the gluteus minimus. Externally
an oblique line runs downward and forward, indicating the
inferior border of the gluteus medius insertion. Lower down
is a horizontal line continued to the tubercle of the femur, which
is situated in front at the junction of the neck with the great
trochanter; the tubercle is the meeting-place of five muscles—
vastus externus, gluteus minimus, obturator internus, and
two gemelli. Internally, at the base of the trochanter and
rather behind the neck, is the digital fossa, giving attachment
to the obturator externus tendon. Above and in front of
this is the insertion of the obturator internus and gemelli
muscles.

The upper border of the trochanter is narrow, and presents
an oval mark for the pyriformis. The posterior border is
prominent, and continuous with the posterior intertrochanteric
line, limiting the neck posteriorly. Above the centre of this
line is the tubercle of the quadratus, for attachment of the upper
part of the quadratus femoris; sometimes a linea quadrati
passes vertically down from the tubercle.

The small trochanter is a pyramidal eminence projecting
inward and backward from the posterointernal aspect of the
bone at the junction of the neck with the shaft. Its apex
gives attachment to the iliopsoas tendon.

Anteriorly the neck is separated from the shaft by the anterior
intertrochanteric line, which is the upper part of the spiral

THE FEMUR 101

line (does not connect the trochanters); it commences at the
tubercle of the femur, and runs down and in a finger’s breadth
in front of the small trochanter; it gives attachment to the
capsular ligament, the united crureus and vastus internus
muscles.

The shaft is arched with its convexity forward; toward the
middle it is partly cylindrical, and expanded below. It presents
anterior and lateral surfaces without definite lines of demarca-
tion. All these surfaces are covered by the crureus and vasti
muscles. Behind, the lateral surfaces are separated by the
linea aspera. This is a prominent ridge extending along the
middle third of the shaft, bifureating above and below. The
external lip is prolonged up to the great trochanter; its upper
end is strongly marked for the gluteus maximus, constituting
the gluteal ridge. The inner lip winds around below the small
trochanter, merging into the anterior intertrochanteric line
and forming the lower part of the spiral line; rising from the
inner lip, a third line passes up to the small trochanter and
gives attachment to the pectineus.

Inferiorly the two lips are prolonged to the condyles as the
internal and eaternal swpracondylar lines, enclosing the flat
popliteal surface of the femur. The inner line is interrupted
where the femoral vessels lie against the bone, and terminates
below in the adductor tubercle. Above the centre of the linea
aspera is the medullary foramen, directed upward; a second
may exist near the lower end of the bone.

To the inner lip of the linea aspera is attached the vastus '
internus, to the outer lip the vastus externus, and diagonally
between the two the adductor magnus. Between the adductor
magnus and vastus externus are the gluteus maximus and
short head of the biceps; between the adductor magnus and
vastus internus are the iliacus, pectineus, adductor brevis,
and adductor longus. At the lower part of the popliteal space
above each condyle is the origin of one head of the gastroc-
nemius, and externally of the plantaris.

The inferior extremity presents two rounded condyles, united
in front, but separated behind by the intercondylar notch; the
external is broader and more prominent in front, the internal
longer and more prominent internally. The inner aspect of
this condyle and the head of the femur face nearly the same
direction.

102 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

The inferior surfaces of the two condyles are on the same
level in the natural position of the femur. Opposite in front
of the intercondylar notch the whole articular surface is divided
by a faint transverse groove on either side into three parts—
a convex surface on either condyle for the tibia and a grooved |
anterior surface for the patella.

The patellar surface is trochlear in form, marked by a vertical
hollow and two lips; the external portion is wider, more prom-
inent, and rises higher. The tibial surfaces are nearly parallel,
but the internal one turns outward anteriorly to meet the
patellar surface. The exposed lateral surface of each condyle
presents a tuberosity or epicondyle for ligamentous attachment.
The external is the smaller; above it is the impression for
the outer head of the gastrocnemius; below and behind it is
an oblique groove ending inferiorly in a pit from which rises
the popliteus muscle; its tendon sinks fully into the groove
only when the knee-joint is flexed. The inner head of the
gastrocnemius rises from the upper part of the inner condyle.

The intercondylar fossa presents two impressions for crucial
ligaments; that for the anterior ligament is on the posterior
part of the inner surface of the external condyle; that for the
posterior ligament is on the forepart of the external surface
of the inner condyle.

The angle of the neck with the shaft is open in the fetus and
child, then lessens under the weight of the body, but under-
goes no change after growth is completed. The upper part
of the gluteal ridge may form a third trochanter.

The Patella

The patella, or knee-pan, is a sesamoid bone developed
in the tendon of the quadriceps extensor cruris. It is some-
what triangular, with its apex below. Its anterior surface
is convex and striated, and pierced by vascular foramina.
The superior border is broad and sloped from behind down-
ward and forward, and gives attachment to the rectus and
crureus portions of the quadriceps extensor.

The posterior surface of the bone presents two vertical and
two transverse ridges; one vertical ridge is close to the inner
margin; the other is distinct and divides the surface into two
parts, the external of which is the larger and transversely
concave, the inner smaller portion is convex.

THE TIBIA 1038

The faint transverse ridges divide the articular surface
into an upper two-sixths, a middle three-sixths, and a lower
one-sixth. In usual extension the lower one-sixth is in contact
with the femur, in mid-flexion the middle three-sixths, and
in extreme flexion the upper two-sixths; also in extreme flexion
the thin marginal facet is the part in contact with the inner
condyle. Below the articular surface is a rough triangular
area; the ligamentum patellz springs from the apex.

Place the patella upon a plane surface, its apex away from
you and its anterior surface up. It will tip to the side to which
it belongs.

THE BONES OF THE LEG

The Tibia

The tibia (flute), or shin bone, is the inner and anterior of
the two bones of the leg, and transmits the weight of the trunk
to the foot. It articulates with the femur, fibula, and astragalus;
has a shaft and two extremities.

The superior extremity, or head, is thick and broad trans-
versely. It forms on each a tuberosity. These are continuous
in front, but separated behind by a notch, the popliteal.

On the upper aspect of each tuberosity is a concave articular
surface for the condyles of the femur. The internal tuberosity
is larger than the external, and marked posteriorly and internally
close below the articular surface by a horizontal groove for
the semimembranosus.

The condylar surface is oval, more hollowed than the external,
and longer.

The external tuberosity at the junction of the anterior and
outer surfaces forms a prominent tubercle for the insertion of
the iliotibial band; below this are often attached a few fibers
of the extensor longus digitorum and of the biceps. At the
posterior and under part is a flat articular surface for the
fibula, looking down, out, and back. The external condylar
surface is nearly circular, concave from side to side, and more
or less convex from before backward; it is prolonged a little
posteriorly where the popliteus glides. The periphery of each
articular surface is flattened for the semilunar fibrocartilage.

104 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

Between the condylar parts is an interval which is depressed
in front and behind for attachment of crucial ligaments, and
elevated in the middle, forming the spine, the summit of which
presents two compressed tubercles with an intervening hollow.
The depression behind the spine is continued into the popliteal
notch, which separates the tuberosities posteriorly. Anteriorly,
at the junction of the head and shaft, is the tubercle or anterior
tuberosity, the lower half of which gives attachment to the
ligamentum patelle.

The shaft is three-sided, diminishing in size as it descends
for about two-thirds of its length, and then increasing again.
It presents three borders and three surfaces.

The anterior border runs sinuously from the tubercle to the
front of the inner malleolus; its upper two-thirds is the crest of
the tibia; its lower third is smooth. It separates the internal
and external surfaces.

The internal border, which is most distinct in the middle
third of the bone, commences above at the back part of the
inner tuberosity, ending below at the posterior border of the
internal malleolus. It separates the internal and posterior
surfaces.

The external border, or interosseous ridge, is thin and sharp
in its middle portion. It separates the external and posterior
surfaces, and gives attachment to the interosseous membrane.

The internal surface is convex and nearly subcutaneous.
At the inner side of the tubercle are the insertions of the gracilis,
semitendinosus, and double insertion of the sartorius. The
external surface is hollowed in its upper two-thirds, where it
lodges the tibialis anticus; below this the surface runs forward
and is covered by the extensor tendons. The upper third
of the posterior surface is crossed obliquely by. the popliteal
or oblique line, running down and inward; it gives origin to
the soleus. Above it is a triangular area occupied by the |
popliteus; below it, in the middle third of the shaft, is a longi-
tudinal ridge marking off two portions, an inner for the flexor
longus digitorum, and an outer for the tibialis posticus. Below
the oblique line a large medullary canal runs downward.

The inferior extremity is broad from side to side, and pro-
jects downward internally to form the inner malleolus. This
malleolus is marked posteriorly by a groove for the tibialis
posticus tendon, and more externally by a depression for the

THE FIBULA 105

flexor longus pollicis. The external surface of the extremity
is hollowed for the fibula, and rough for ligaments except
along the lower border. Below is an articular surface, quadri-
lateral, concave, narrower behind than in front. It shows a
slight median elevation separating two lateral depressions.
Internally the cartilaginous surface is continued upon the inner
malleolus.

The Fibula

The fibula (clasp), or peroneal bone, nearly equals the tibia
in length; its purpose in the leg is mainly for elasticity. Its
shaft is convex backward, and its lower extremity is placed
a little in advance of the upper.

The upper extremity, or head, is prolonged upward at its
back part into the styloid process; inside this is a facet looking
upward, inward, and forward for articulation with the tibia;
more externally is a slight excavation for the biceps; the pero-
neus longus is attached in front and the soleus behind. A
somewhat constricted part below the head is the neck.

The lower extremity, or external malleolus, is pyramidal and
longer than the internal malleolus; internally it shows a tri-
angular, smooth, articular surface for the astragalus, and
behind this a depression for the posterior band of the external
lateral ligament.

Posteriorly is a shallow groove for the peroneus longus
and brevis tendons. Externally this extremity is convex and
subcutaneous.

The shaft presents four surfaces—anterior, posterior, internal,
and external; and four borders—anteroexternal, anterointernal,
posteroexternal, and posterointernal. (Gray.)

The anteroexternal border begins in front of the head and
bifureates below to embrace the triangular subcutaneous
surface of the external malleolus; this border is between the
peroneal and extensor muscles.

The anterointernal border, or interosseous ridge, is close to
the preceding and parallel with it in the upper third. It ter-
minates below at the apex of a rough surface just above the
articular facet. The attached interosseous membrane separates
the extensors in front from the tibialis posticus behind.

The posteroexternal border commences at the base of the
styloid process and terminates below in the posterior border

106 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

of the external malleolus. It is directed out above, then back,
then slightly inward below. It separates the peronei from the
flexor muscles. The posterointernal border, or oblique line,
commences inside the head, and ends by joining the interosseous
ridge in the lower fourth of the bone.

The anterior surface is very narrow above, besades and
grooved below; to it are attached the extensor proprius pollicis
pedis (extensor proprius hallucis), the extensor longus digi-
torum, and the peroneus tertius.

The external surface is directed outward above and back-
ward below, and is occupied by the peroneus brevis and longus
muscles. |

The internal surface between the anterointernal and postero-
internal borders is grooved for the tibialis posticus.

The posterior surface looks backward above and directly
inward below. Its upper third attaches the soleus muscle; its
lower part is rough for interosseous ligaments; to the rest of the
surface is attached the flexor longus pollicis. The medullary
canal opens on this surface and is directed downward.

THE BONES OF THE FOOT

The tarsus is composed of seven bones—the calcaneum, or
os calcis, and the astragalus, the navicular, or scaphoid, three
cuneiform, and cuboid,

The Os Calcis

The os calcis (heel) is the largest bone of the foot; it articulates
with the astragalus above and cuboid in front. The bone
presents six surfaces. The posterior extremity, or tuberosity,
presents inferiorly two tubercles; the inner is the larger. Its
posterior surface presents three districts—a smooth one above
for a bursa, a ligamentous one for the tendo Achillis, and a_
lower convex part for the pad of the heel. The part in front
of the tuberosity forms a slightly constricted neck.

The internal surface is deeply concave, and surmounted
above by the sustentaculum tal (support of the talus, 2. e.,
ankle bone or astragalus); this projects inward on a level
with the upper surface, and is grooved beneath for the flexor

THE ASTRAGALUS 107

longus hallucis. The superior surface has two articular facets,
separated by a groove which runs forward and outward for
.the interosseous ligament. The anterior facet, often subdivided
into two, is on the sustentaculum, and is concave longitudinally ;
the other one is convex. At the forepart of the groove is a
roughness for the- extensor brevis digitorum. Behind the
articular surfaces is a region convex from side to side and
concave from before backward; above it is placed adipose
tissue in front of the tendo Achillis.

The anterior surface is concavoconvex for articulation with
the cuboid.

The infertor surface, in front of the tuberosity, projects in
an anterior tubercle with a transverse groove in front, and
gives attachment to an inferior caleaneocuboid ligament.

The eaternal surface is usually flat, and presents near the
centre a tubercle for the middle fasciculus of the external
lateral ligament, and anteriorly often a peroneal spine, separat-
ing two grooves—the upper for the peroneus brevis tendon,
the lower for that of the peroneus longus.

The Astragalus

The astragalus (a die), or talus, receives the weight of the
body from the leg. It articulates with four bones—the tibia
above and internally, the fibula externally, os calcis below,
and scaphoid in front. Its long axis is forward and inward.
The main part is the body, the convex anterior portion the
head, just behind which is the neck.

The superior articular surface occupies the whole of the
upper surface of the body and sends a prolongation down on
either side. The trochlear part is convex from below back-
ward, and slightly concave from side to side, wider in front
than behind; its outer margin is longer than the inner, and
curved, while the inner is straight. The inner lateral part is
sickle-shaped for the internal malleolus; the outer lateral part
is concave and triangular, and articulates with the external
malleolus. IJnfervorly there are two articular surfaces for the
caleaneum; the posterior one is concave,’ separated by the
interosseous groove from the anterior one, which is convex.
The head articulates anteriorly with the scaphoid; at the lower
and inner part, between this and the anterior articulation for

108 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

the os calcis, is a facet resting upon the inferior caleaneoscaphoid
ligament, the three forming one continuous surface.

The posterior surface is small and narrow, and marked by
a groove for the flexor longus pollicis. Bounding the groove
are two tubercles, the external more prominent and giving
attachment to the posterior band of the external lateral liga-
ment.

The Cuboid

The cuboid (os cuboideum) is found on the lateral aspect
of the tarsus, between the os calcis and the fourth and fifth
metatarsal bones, external to the scaphoid and external cunei-
form bones. It is pyramidal in shape, its base directed inward
and its apex outward. It presents for examination six surfaces,
three non-articular—dorsal, plantar, and external; three articular
——posterior, anterior, internal.

Articulations.—The posterior surface with the os calcis,
the anterior surface (two facets) with the fourth and fifth
metatarsal, the internal surface with the external cuneiform,
(occasionally) the scaphoid.

Attachments of Muscles.—Part of the flexor brevis hallucis
and a slip from the tendon of the tibialis posticus. It also
receives the attachments of several ligaments.

Scaphoid or Navicular

Is situated at the inner aspect of the tarsus, between the
astragalus and the three cuneiform bones. It presents for
examination anterior, posterior, dorsal, plantar, internal, and
external surfaces.

Articulations.—Astragalus and three cuneiform bones.

Attachment of Muscle.—Part of tibialis posticus.

The Cuneiform

The cuneiform bones are three in number—internal, middle,
and external—found between the scaphoid behind, the first,
second, and third (sometimes the fourth) metatarsal bones
in front, the cuboid externally.

THE METATARSAL BONES 109

_ The internal cuneiform presents for examination—internal,
external, anterior, posterior, plantar, and dorsal surfaces.

Articulations.—Scaphoid, middle cuneiform, first and second
metatarsal bones.

Attachments of Muscles.—Tibialis anticus and posticus and
peroneus longus. Also receives attachments of ligaments.

The middle cuneiform presents the same surfaces as_ the
preceding bone.

Articulations.—Scaphoid, internal, and external cuneiform,
and second metatarsal.

Attachment of Muscles.—A slip from the tibialis posticus.

The external cuneiform is situated between the scaphoid
behind, the third metatarsal in front, the middle cuneiform
internally, and the cuboid externally. It presents the same
surfaces as the former bone.

Articulations.—Scaphoid, middle cuneiform, cuboid, and
second, third, and fourth metatarsal bones.

Attachments of Muscles.—Part of tibialis posticus and flexor
brevis hallucis. Also receives attachments of ligaments.

The reader is referred to the standard anatomies for a more
detailed description of the tarsal bones (Author).

The Metatarsal Bones

The metatarsal bones are one to five in number; they articu-
late with the tarsal bones behind and the respective phalanges
in front. They present for examination a shaft, a proximal
extremity, or base, a distal extremity, or head.

The first is the shortest and thickest, the second is the
largest, and the fifth the thinnest. Each bone has a nutrient
canal on its plantar surface.

Articulations.—

Iirst bone (proximal extremity) internal cuneiform, second meta-
tarsal (occasionally).

heen middle, external cunei-

tee sy form.
Second bone peed and (occasionally) first meta-
tarsal.
Third bone fs external cuneiform, second and
fourth metatarsal.
Fourth bone ‘ e external cuneiform, cuboid, third

and fifth metatarsal.
Fifth bone y at cuboid and fourth metatarsal.

110 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM

The distal extremity of each bone articulates with the
corresponding proximal extremity of the first phalanx.

Attachment of Muscles.—

First bone. Part of tibialis anticus, peroneus longus, and first dorsal
interosseous.

Second bone. Adductor obliquus hallucis, first and second dorsal
interosseous, a slip from the tibialis posticus; occasion-
ally a slip from the peroneus longus.

Third bone. Adductor obliquus hallucis, second and third dorsal
and first plantar interossei, and a slip from the tibialis
posticus.

Fourth bone. Adductor obliquus hallucis, third and fourth dorsal
and: second plantar interossei, and a slip from the
tibialis posticus.

Fifth bone. Peroneus brevis, peroneus tertius, flexor brevis minimi
digiti, adductor transversus hallucis, fourth dorsal
and third plantar interossei.

The Phalanges of the Foot

The phalanges are fourteen in number for each foot, allowing
three (Ist, 2d, and 3d) for the second, third, fourth, and fifth.
toes; while the first has only two (Ist and 2d).

The first or proximal phalanx is long and thin and presents a
proximal extremity for articulation with the metatarsal bone;
and a distal extremity for articulation with the second phalanx.

The second phalanx is shorter and smaller and articulates
with the proximal and distal phalanges.

The third or distal phalanx is still smaller, and more flattened
than the others, articulating by its proximal extremity with
the second phalanx, and its expanded dorsal extremity sup-
ports the nail and the end of the toe. 3

Attachment of Muscles.—To first phalanges:

Great toe. Innermost tendon of extensor brevis digitorum, abductor
hallucis, adductor obliquus hallucis, flexor brevis
hallucis, adductor transversus hallucis.

Second toe. First and second dorsal interossei; first lumbrical.

Third toe. Third dorsal and first plantar interossei; second lumbrical.

Fourth toe. Fourth dorsal and second plantar interossei and third
lumbrical.

Fifth toe. Flexor brevis minimi digiti, abductor minimi digiti, third
plantar interosseous, and fourth lumbrical.

THE PHALANGES OF THE FOOT 111

To second phalanges:

Great toe. Extensor longus hallucis, flexor longus hallucis.

‘Other toes. Flexor brevis digitorum, one slip of the common tendon of

the extensor longus and brevis digitorum.

To third phalanges: Two slips from the common tendon
of the extensor longus and brevis digitorum, and the flexor
longus digitorum.

QUESTIONS ON OSTEOLOGY

What is the anatomical position?

What is the periosteum?

Into how many and what classes are bones divided?
The skeleton is composed of what structures?

THE BONES OF THE TRUNK

How many vertebre are there?

How many vertebre in each region?

Describe a typical vertebra of each region.

By what characteristics may the vertebre of the different regions be
distinguished?

What are the atypical cervical vertebrze?

Of what is the atlas composed?

Why has the atlas no real spinous process?

Describe the atlas.

Describe the axis.

How many separate articular surfaces or facets has the axis?

What motion takes place between the atlas and axis?

How does the vertebra prominens differ from the type of its
region?

What are the atypical thoracic vertebre? Describe each.

What thoracic vertebre have no articular facets on their transverse
processes?

What is the sacral angle?

With what does the sacrum articulate?

What ligaments are attached to the sacrum and coccyx?

What are the surfaces of the hyoid bone?

THE BONES OF THE HEAD

Name in order the articulations of the occipital bone.

Describe the external surface of the occipital, giving muscular
attachments.

What is just in front of the jugular process?

What do the anterior and posterior condylar foramina transmit?

What Sp through the foramen magnum?

What lodges the occipital sinus?

Name in order the articulations of the parietal, frontal, temporal,
sphenoid, malar, nasal, and lachrimal bones. _

Where is the parietal foramen, and what does it transmit?

In what general direction do the grooves for the meningeal arteries
run in the parietal bone?

What and where is the parietal boss?

What are the fontanelles?

Between what borders of what bones is the sagittal suture?

Describe the lambdoid and coronal sutures.

Into what portions is the frontal divided?

What do the internal angular processes articulate with?

What do the ethmoidal canals transmit?

Where is the supraorbital notch?

Into what portions is the temporal bone divided?

Describe minutely the articulations of the squamous portion,
including the glenoid fossa.

Describe the zygomatic process, giving the direction of its articula-
tion and its muscular attachment.

ca is the vaginal process of the temporal, and what is attached
to it

What is the direction of the petrous portion of the temporal?

What foramina are seen entering it?

Where is the depression for the Gasserian ganglion?

What does the petrous portion articulate with?

Describe the mastoid process.

Where is and what passes through the stylomastoid foramen?

Describe the superior surface of the body of the sphenoid?

Where are the middle clinoid processes?

What passes through the optic foramen?

What is the lingula of the sphenoid?

What are the surfaces of the great wing of the sphenoid?

Give the articulation of the orbital plates of the sphenoid in order.

Name the structures passing through the sphenoidal fissure and
give its relations.

Name the foramina piercing the greater wing of the sphenoid, and
tell what they transmit. /

Describe the roots of the lesser wing.

What does the posterior margin of the lesser wing mark?

heed what part of the sphenoid do the pterygoid processes
arise? . |

On what plate of the pterygoid process is the hamular process?

To what does the posterior margin of the inner pterygoid plate give
attachment?

With what does the rostrum of the sphenoid articulate?

Describe the cribriform and perpendicular plates of the ethmoid,
giving articulations.

Which turbinated bones belong to the ethmoid?

Describe the lateral masses.

Describe the malar, nasal, and lacrimal bones.

What are the surfaces of the superior maxillary bone?

Describe the surfaces of the superior maxilla.

Into which nasal fossa does the antrum of Highmore open?

Where is the apex of this antrum found?

Give the articulations of the orbital plate of the superior maxilla.

Describe the infraorbital groove.

How many teeth are there in each superior maxilla?

Describe the palate process of the superior maxilla.

Into what fossze does the palate bone enter?

What are the processes of the palate bone?

What does the vomer separate behind?

With what does the vomer articulate?

Describe the inferior turbinated bone.

Into what portions is the inferior maxilla divided?

What are the muscular attachments of the rami?

Describe the nasal fosse, orbital fosse, zygomatic fosse, spheno-
maxillary fosse, pterygoid fosse, and temporal fossz.

THE THORAX

How many true ribs are there?

How many false ribs are there?

In what direction do the surfaces of the ribs look in front of and
behind the angle?

With how many and what structures does the head of a rib articulate?

Describe the first rib.

What structures pass between the clavicle and the first rib?

Of how many parts is the sternum composed?

What ribs articulate with each, and how?

Describe the sternum as a whole.

THE BONES OF THE UPPER EXTREMITY

Into what two portions is the clavicle divided?
Which aspect of the inner portion is concave?
Describe the sternal extremity of the clavicle.
Describe the clavicle as a whole, giving precisely the muscular
attachments.
Name the angles of the scapula.
Name the margins of the scapula, and tell what is attached to each.
What is attached just above and what below the glenoid fossa?
Describe the glenoid fossa.
What are the borders of the acromion process, and with what are
they continuous?
In what directions do the surfaces of the acromion process look?
Just where does the coracoid process arise?
Nib borders does it present, and what structures are attached to
them .
What is attached to the apex of the coracoid process?
What are the surfaces of the humerus? Name and trace its borders.
What is the direction of the musculospiral groove?
What does the anatomical neck separate?
Describe the head of the humerus.
Name the muscles attached by the common extensor tendon to the
external epicondyle (condyle).
Name muscles with an attachment on the internal epicondyle
(condyle).
Describe the capitellum and trochlear surface.
What are the surfaces of the radius?
What surfaces has the ulna that the radius has not?
Name the borders of the radius and ulna. -
Describe the extremities of the ulna and radius.
Name the muscles having attachment on the radius, stating the
position and extent of each.
Into what divisions is the posterior surface of the ulna divided, and
what is attached to each of these divisions?
Po muscles receive partial origin from the posterior margin of the
ulna?
Name the tendons which pass over the distal extremity of the
radius, and point out the grooves for them.
Name the carpal bones.
Take each carpal separately and tell in order all the bones articu-
lating with it.

THE BONES OF THE LOWER EXTREMITY

Of what bones is the os innominatum made up?

Describe the crest of the ilium, giving muscular attachments.

Describe the dorsum ilii.

Describe the internal iliac surface.

What portion of the ilium forms part of the true pelvis?

What structures are attached to the antero-inferior iliac spine?

Describe the three surfaces of the body of the ischium.

What is attached to the apex of the spine of the ischium?

What are the surfaces of the tuberosity of the ischium?

How is the postero-inferior surface of the tuber ischii subdivided,
and what are attached to these subdivisions?

What fraction of the acetabulum is formed by the ischium?

Into what portions is the pubis divided?

Describe the body of the pubis.

Describe the superior ramus of the pubis.

What stretches between the anterior superior iliac spine and the
pubic spine?

In what direction does the head of the femur look?

Describe the neck of the femur.

Where is the digital fossa?

Describe the great trochanter, giving muscular attachments.

What is the direction of the lesser trochanter?

What is the quadrate line?

Describe precisely the linea aspera with its muscular attachments. |

What are the surfaces of the femur?

Describe the lower extremity of the femur.

What is the direction of the groove for the popliteus tendon?

Describe the patella.

How may you tell to which side a fibula belon

What is the lowermost portion of the fibula called?

To which border of the fibula is the interosseus membrane attached?

What are the surfaces of the tibia? Give the arrangement of their
muscular attachments.

Where is the popliteal notch?

Where is the spine of the tibia?

Describe the tuberosities of the tibia.

Describe the tubercle of the tibia.

Describe the distal extremity of the tibia.

What tendons groove the lower end of the tibia?

What bones form the ankle-joint?

Name the tarsal bones, and give the articulations of each.

What structures does the peroneal spine separate?

Describe the os calcis.

PA Lt

ARTHROLOGY, OR THE ANATOMY OF THE
ARTICULATIONS

THE GENERAL STRUCTURE OF JOINTS

Bonss, cartilage, ligaments, and synovial membrane enter
into the formation of joints.

The articular portions of bones are enlarged to form a joint
of suitable size, and so that muscles passing over the joint
can act at a greater angle. The layer of bone beneath the
cartilage is a compact articular lamella. There are three varieties
of cartilage—hyaline, fibrocartilage, and yellow elastic. The
hyaline and fibrocartilage are utilized in the structure of a
joint.

The ligaments are mainly white fibrous tissue; some are
yellow elastic tissue.

The synovial membrane is like a short wide tube covering
the inner surface of the ligaments; its secretion is synovia,
95 per cent. water, 3.51 per cent. albumin and salts. There
are three kinds of synovial membrane—articular, bursal, and
vaginal. ‘The former in the fetus is said to cover the articular
cartilages as well as ligaments.

The burse are mucous as between integument and bone
(subcutaneous synovial burs), and synovial between muscles
or tendons and bone (subtendinous synovial burse).

Vaginal synovial membranes are sheaths for tendons.

114 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

THE CLASSIFICATIONS OF JOINTS

GRAY’S CLASSIFICATION OF JOINTS

Gray classifies them as synarthrodial, immovable; amphi-
arthrodial, mixed; and diarthrodial, movable.

Synarthrodial, |
immovable

Amphiarthro- |

dial, mixed

Diarthrodial,
movable

| dentata—e. g., interparietal.
vera serrata—e. g., interfrontal.
(true) | limbosa—e. g., frontopari-
L etal. |
Sutura - squamosa—e. g., squamo-
notha | parietal.
(false) | harmonia—e. g., intermax-
illary.

Schindylesis—e. g., rostrum of sphenoid and

vomer.

Gomphosis—e. g., tooth in alveolus.

(1) Surfaces connected by fibrocartilage, not
separated by synovial membrane—e. 4.,
bodies of vertebree.

(2) Surfaces covered by fibrocartilage and
partially lined with synovial membrane—
e. g., pubic symphysis.

Arthrodia, gliding (not referable to any axis)—

e. g., carpal and tarsal articulations.

Enarthrosis, ball-and-socket—e. g., shoulder and

hip.

Ginglymus, hinge—c. g., elbow, knee; no lateral

motion.

Trochoides, or pivot-joint, or lateral ginglymus,

a pivot within a ring—e. g., altoaxoid.

Condyloid, ovoid head in elliptical cavity—e. @.,

wrist.

Reciprocal reception, saddle-shaped—e. g., carpo-

metacarpal joint of thumb.

The apposition of joint surfaces is accomplished by (1)
atmospheric pressure—e. g., hip-joint; (2) synovial fluid; (3)

THE LIGAMENTS OF THE BODIES — 115

ligaments to a small extent; (4) muscles, to the greatest extent.
A short muscle may act on more than one joint; the gluteus
maximus extends the hip and also the knee through fascia
lata which overlies the rectus femoris.

The limitation of joint motion is due to (1) extent of articular
surfaces; (2) bony contact; (8) approximation of soft parts;
(4) manner of articulation; (5) anatomical separation of joint
into two, as the joints of a vertebra.

ARTICULATIONS OF THE TRUNK

THE ARTICULATIONS OF THE VERTEBRAL COLUMN

Articulations of the vertebral column comprise five sets:
(1) Those between the bodies of the vertebrae; (2) between
the lamine; (3) between the articular; (4) the spinous; (5) and
the transverse processes (the last four varieties being known as
interneural).

The Ligaments of the Bodies

Anterior common, posterior common, and _ intervertebral
substance.

The antertor common ligament extends along the front of
the bodies, filling the concavities of the vertebree from axis
to sacrum; it is broader below than above, and thicker oppo-
site the front of the body, where it is loosely connected, than
opposite the intervertebral disk, where it is closely connected.
It consists of several layers of fibers, the superficial set extend-
ing from a given vertebra to the fourth or fifth below it; the
middle or second set extend between two or three vertebre;
and the third or deep set from one to another. The ligament
splits for the passage of vessels to the vertebral body.

The postertor common ligament is inside the spinal canal,
along the posterior surface of the bodies, and extends from
the axis to the sacrum. It is broader above than below, and
laterally presents a series of dentations over the intervertebral
disks, and concavities over the centres of the bodies, from
which it is separated by the vene basis vertebre. It has

116 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

denser fibers than the anterior ligament, which are similarly
divided into sets, and attached in a similar manner.

The intervertebral substances are disks of fibrocartilage placed
between the bodies of the vertebre from the axis to the sacrum.
They vary in size and thickness in the different regions, being
thicker behind than in front in the lumbar and cervical regions,
and uniformly thick in the dorsal region. ‘They form about

Fig. 20

POSTERIOR
COMMON

im,
ANTERIOR COMMON LIGAMENT. ; TEI y
‘| PX
Noni ZN

LIGAMENT.
s aN
Ay —

PP eo

——
ap aes rae
WN Wy '\

MLL,

ne

Vertical section of two vertebre and their ligaments, from the lumbar region.

one-fourth of the spinal column or one-third of the lumbar
region, one-fourth of the cervical and one-fifth. of the dorsal.
They are connected with the anterior and posterior common
ligaments, and in the dorsal region with the heads of ribs.
They are composed at the circumferenee of laminze 7}, to
+5 inch (| to $ mm.) broad, of fibrous and fibroelastic tissue
and fibrocartilage arranged concentrically one within the other,

THE LIGAMENTS OF THE PROCESSES 117

and surrounding in the centre a soft, pulpy mass. The lamine
are not composed of different materials, but owe their differ-
ence in appearance to the fact that they are obliquely placed,
crossing each other like an X, and the light strikes them differ-
ently; some fibers run horizontally. The most external fibers
resemble those of a tendon. 3

The central part is pulpy, soft, and yellow, containing cells
in a fibrous matrix; it rises up conically when pressure is
removed. The. intervertebral disks are compressible, and,
according to one set of measurements, a man is 4 inch taller

in the morning than at night.

The Ligaments of the Lamine

Those connecting the laminz are the ligamenta subflava,
of yellow elastic tissue attached to the anterior surface of
the lamina above and the posterior surface and upper margin
of the lamina below. They are analogous to the intervertebral
substances in front. Each ligament consists of two lateral
portions, which commence on each side of the root of either
articular process and pass to the convergence of the lamine.
They do not exist between the occiput and atlas, atlas and
axis; they take the place of active material and help muscles
pull back the flexed column.

The Ligaments of the Processes

The ligaments of the articular processes are capsular, thin,
loose sacs attached to their margins and completed internally
by the ligamenta subflava. They are lined by synovial mem-
brane.

The «wterspinous ligaments are thin and membranous,
interposed between the spinous processes, each extending from
near the root to the summit of each spinous process. They
are slightly developed in the neck, narrow in the dorsal region,
and thicker in the lumbar.

The supraspinous ligament is a strong cord connecting the
apices of the spinous processes down from the seventh cervical.
Its most superficial fibers connect three or four vertebrae and
its deepest neighboring vertebre.

The ligamentum nuche continues the supraspinous ligament

118 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

upward in the neck, and is attached to the external occipital
protuberance. In the human subject it is only an intermuscular
septum between the two trapezii. A fibrous slip is given off
from its anterior surface to each cervical spinous process.

The intertransverse ligaments are interposed between the
transverse processes. ‘They are scattered fibers in the cervical
region, rounded cords in the dorsal, and membranous in the
lumbar.

The Movements of the Spinal Column

The movements of the spinal column are flexion, extension
lateral movement, circumduction, and rotation—all on three
axes, one transverse, one anteroposterior, and one vertical.
Flexion is the freest of all movements; it compresses the disks
in front and stretches the posterior common ligament and
ligamenta subflava. Extension is not marked, and is limited
by the anterior common ligament and spinous processes.

Flexion and extension are most free in the lumbar region
and least in the upper dorsal; extension is greater in the neck
than flexion. Lateral movement is most free in the cervical and
lumbar regions, limited by the approximation of transverse
processes. Circumduction is limited. Rotation is free in the
upper dorsal and absent in the lumbar region. So the cervical
region enjoys the greatest extent of each variety; the dorsal
has greatest rotation, while the lumbar has none. The head
and trunk may be turned through 180 degrees on either side,
head and neck through 79 degrees—three-fifths of it is between
atlas and axis; back and loins through 28 degrees; and in joints
below this through 73 degrees.

The movements are due largely to the shape of the disks,
which limit the extent of motion, but not the direction; it
is proportional to their height and inversely as their area.

The vertebral articulations are supplied by the spinal nerves
in each region; by the vertebral and ascending cervical arteries
in the neck, the intercostal and lumbar below.

The Articulations of the Axis with the Atlas

The ligaments connecting the atlas and axis are two anterior
atloaxoid, the posterior atloaxoid, transverse, and two capsular.
The two anterior atloavoid (anterior obturator) comprise a

ARTICULATIONS OF THE AXIS WITH THE ATLAS 119

superficial rounded cord in the median line, a continuation
up of the anterior common ligament to the occiput, and a
deeper portion on either side from the anterior arch of the atlas
to the base of the odontoid and front of the body of the axis.
In front of them are the recti capitis antici majores muscles.

The posterior atloaxoid (posterior obturator) ligament is
broad and thin, connecting the posterior arches of the two
bones and supplying the place of the ligamenta subflava;
it contains a little elastic tissue. Behind it are the inferior
oblique muscles.

Fia. 21

Bie

The vertical portion of
ODONTOID LIGAMENTS.

eRe Ke: and synovial

occiprto { CAPSULAR LIGAMENT
membrane.

CAPSULAR LIGAMENT
ATLANTO- p
aaa! 1 and synovial

memobrane..

OCCIPITO-AXOID LIGAMENT, divided and turned back.

Occipitoaxial and atlantoaxial ligaments. Posterior view, obtained by removing
the arches of the vertebre and the posterior part of the skull.

The transverse or cruciform ligament passes across the ring
of the atlas behind the odontoid. It holds the odontoid in
place, but not with such firmness as is often described; it is
broad and firm in the middle, and in it is often developed a
cartilaginous nodule; on each side it is attached to the lateral
mass of the atlas. A small process passes up (superior crus)
from its upper border to the basilar process, and another
down (inferior crus) to the root of the odontoid posteriorly.

120 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

The capsular ligaments are thin and loose, strongest in front
and externally; there is also a capsule for the anterior odonto-
atloid articulation. The synovial membranes are four in
number—one for each capsular ligament, one for the anterior
articular surface of the odontoid, and one for its posterior
surface, a sort of bursa which may communicate with the
occipitoatloid joints. The atloaxoid joint possesses great
mobility, the greater part of the rotation of the head occurring
here, and none in the occipitoatloid joints. When the bones
are covered by articular cartilage, a sagittal section shows a
convexity upon a convexity. With the head equipoised and
eyes to the front, the muscles are at rest and ligaments tense.
When the head is rotated the point of the atlas sinks down
off the axis and a part projects; otherwise an already tense
ligament would become more tense in rotation did not the
points of attachment approach each other.

The spinal column is connected to the cranium by ligaments
from the occiput to the atlas, from the occiput to the axis.

The Articulations of the Atlas with the Occipital Bone
(Articuloatlantooccipitalis)

There are anterior occipitoatlantal and posterior occipito-
atlantal, and two capsular ligaments.

The anterior occipitoatlantal passes from the anterior
margin of the foramen magnum to the anterior arch of the
atlas; behind it are the odontoid ligaments. Laterally, it is
continuous with the capsular ligament. In the middle line
in front it is strengthened by a strong, narrow, rounded cord,
which is attached above to the basilar process of the occiput,
and below to the tubercle on the anterior arch of the atlas,
which is a continuation of the anterior common ligament.

The posterior occipitoatlantal is membranous and blended
with the dura mater of the cord; it passes from the posterior
margin of the foramen magnum to the posterior arch of the
atlas. Laterally, it is pierced by the vertebral’ artery and
suboccipital nerve.

The capsular ligaments are loose, and enclose a synovial
membrane, which usually communicates with that between
the posterior surface of the odontoid and transverse ligament.

ARTICULATIONS OF THE RIBS AND VERTEBRA 121

This is a double condyloid joint. The movements in the
joint are flexion and extension, a nodding movement through
about 45 degrees; there is a slight lateral motion.

The Ligaments Connecting the Axis with the Occipital
Bone

There are the occrpitoaxial and three odontoid. To expose
these the spinal canal must be opened. The occipitoaxial
ligament prolongs the posterior common ligament of the spine
to the front of the foramen magnum, and there blends with
the dura. This is the broad ligament of the axis, and shows
three sets of fibers; the posterior blends with the dura, the
next is the continuation of the posterior common, and the
most anterior or deepest set is confined to the back of the
odontoid and body of the axis; this deepest layer also joins
the upper part of the posterior surface of the transverse liga-
ment, and is called the superior appendix of the transverse
ligament. A bursa is often between the broad and the trans-
verse ligament.

From either side of the apex of the odontoid process an
alar or check ligament passes up and out to the inner side of
the condyle of the occiput. They limit the extent of rotation.
From the apex of the odontoid a middle band passes to the
front of the foramen magnum.

Nerves of these joints are from the suboccipital and second
cervical; arteries are from the vertebral.

THE ARTICULATIONS CONNECTING THE RIBS WITH
THE VERTEBRA:

There are two sets: (1) Connects heads of the ribs with the
bodies—costocentral; (2) connects necks and tubercles with
the transverse processes—costotransverse.

1. Costocentral.— Anterior costovertebral or stellate capsular, and
interarticular. The costocentral consists of three bundles of
fibers radiating from the head of the rib; the upper bundle
passes to the vertebra above, the lower to the vertebra below,
and the middle to the intervertebral substance. The first rib
articulates with one vertebra, sends up a slip to the seventh

122 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

cervical, a middle one to the first dorsal, but not a lower one;
there is a similar arrangement with the tenth, eleventh, and
twelfth ribs. On the under edge of the stellate ligament a
deep fasciculus passes from the side of the body to the under
surface of the head of the rib.

The stellate ligament is continued into the cervical and
lumbar regions; a slip from a next higher vertebral body and
one from the adjacent intervertebral disk or body run to the
root of the transverse process.

The capsular ligament is a loose bag, most distinct above
and below, and firmly connected with the stellate ligament.

The interarticular ligament is a flat horizontal band of fibers
passing from the intervertebral substance to the crest on the
head of the rib; it divides the joint into non-communicating
cavities, each lined with a separate synovial membrane. The
first, eleventh, and twelfth ribs do not possess this ligament.

2. Costotransverse.—Articulations of necks and_ tubercles
with the transverse processes—superior, middle (interosseous),
and posterior costotransverse and capsular ligaments.

The superior ligaments are two in number: The anterior
passes from the upper border of the neck of each rib up and
out to the lower border of the transverse process and neck
of the rib above. Its inner border completes an aperture be-
tween it and the articular process, corresponding to an anterior
sacral foramen. Its external border is continued in a thin
aponeurosis over the external intercostal muscle. The first
rib does not possess this ligament. The posterior band is less
regular, and extends from the neck of the rib up and into the
transverse and lower articular process next above.

The middle costotransverse is very short, and connects the
neck of the rib to the front of the adjacent transverse and
articular process. This is lacking in the case of the eleventh
and twelfth ribs.

The posterior costotransverse passes obliquely from the summit
of the transverse process to the tubercle of the adjacent rib
and is accessory to the capsule behind—wanting on the eleventh
and twelfth ribs. The joint has a thin capsular ligament
enclosing a synovial membrane.

Nerves are anterior branches of spinal BeNveRs arteries, the
intercostals.

THE INTERCOSTAL ARTICULATIONS 123

Action of these joints is elevation and depression of ribs on
a transverse axis through the head of a rib and its articular
process—. e., lengthwise through its neck; there are also ever-
sion and inversion of ribs on an axis connecting their sternal
and vertebral ends. No movement on a vertical axis.

THE ARTICULATIONS OF THE COSTAL CARTILAGES
WITH THE STERNUM (COSTOSTERNAL)

They are anterior chondrosternal, posterior chondrosternal,
capsular, and an intraarticular chondrosternal. The anterior
one is a broad radiating band with the superior, middle, and
inferior fasciculi. They intermingle with those of the opposite
side and with the origin of the pectoralis major, forming a
membrane over the sternum—membrana sterni. The posterior
chondrosternal ligaments are less distinct, and are composed
of radiating fibers blending with the periosteum. The capsular
ligaments are very thin, and connected with the anterior and
posterior ones. ‘The intraarticular chondrosternal ligament
is found between the second costal cartilage and the sternum,
attached by one extremity to the cartilage of the second rib,
and by the other to the cartilage which connects the first
and second portions of the sternum. Sometimes the third
rib has the same ligament situated as above, only located
between the second and third pieces of the sternum. This
joint has two synovial membranes.

Synovial Membranes.—The first cartilage has none, and the
sixth and seventh usually have none; the third, fourth, and
fifth have one; the second has two and an interarticular cartilage
resembling a vertebral articulation. In old age most of these
articulations disappear.

From the sixth and seventh cartilages chondroxiphoid (costo-
xiphoid) ligaments pass down and into the ensiform, strengthen-
ing the sheath of the rectus and limiting the aponeurosis of
the external oblique.

THE INTERCOSTAL ARTICULATIONS (INTERCHONDRAL)

There are external and internal intercostal ligaments. The
former, ligamenta intercostalia externa, lie in the nine or
ten upper spaces between the anterior end of the external

124 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

intercostal muscle and the sternum. The fibers are partly
oblique, vertical, and transverse. The vertical and oblique
fibers constitute the ligamentum corruscans (shining), and
seem to be undeveloped bundles of the external intercostal
muscle; they are strongest in the third to the seventh spaces.
The transverse fibers are present in the first to the seventh
spaces.

The internal intercostal ligaments, ligamenta intercostalia
interna, are tendinous fasciculi of the triangularis sterni
muscle, passing from rib to rib over one or two spaces; in the
seventh and eighth. spaces, sometimes sixth and ninth, they
are nearly transverse.

The cartilages of the sixth, seventh, and eighth ribs, some-
times of the fifth and ninth, articulate by their lower borders
with the margins of the adjoining cartilage; each articulation
has a capsule and synovial membrane. All these articulations
may be wanting.

In articulations of ribs with cartilages the cartilage is held
in a depression in the sternal end of the rib by periosteum.

THE, ARTICULATIONS OF THE STERNUM

The gladiolus is united to the manubrium by an interposed
fibrocartilage, synarthrodial (Henle), or it may be, diarthrodial,
with a synovial membrane in 33 per cent. of cases—rarely
so in childhood—and probably results from absorption. The
ligaments are anterior and posterior intersternal; both consist
of longitudinal fibers blending with the chondrosternal liga-
ments, the anterior with the pectoralis major.

The Temporomaxillary Articulation

The ligaments are capsular, interarticular fibrocartilage,
external lateral, internal lateral, and stylomandibular.

The capsule is very thin and loose; it passes from the edge
of the glenoid fossa to the interarticular cartilage, thence

to the neck of the condyle.
The interarticular disk, or fibrocartilage (articular meniscus),
is placed horizontally between the jaw and temporal bone,
concavoconvex above and concave below. It is connected

THE TEMPOROMAXILLARY ARTICULATION 125

in front with the external pterygoid muscle; it is composed
of concentric fibers; its circumference is thick, and its centre
may be perforated.

There are two synovial membranes: the upper is the larger
and prolonged in front, while the lower is smaller and pro-
longed behind.

The external lateral ligament (ligamentum accessorium
laterale) passes from the outer surface of the zygoma and
‘tubercle; their lower borders down and back to the posterior
surface of the neck of the lower jaw. Externally it is in rela-
tion with the temporal fascia, and internally with the joint
capsule.

Vertical section of the temporomandibular articulation.

The internal lateral ligament (ligamentum accessorium
mediale) has two parts: One passes from the inner margin
of the glenoid fossa to the neck of the condyle behind the
insertion of the external pterygoid muscle; this is in immediate
relation to the capsule, and is known as the short internal
lateral ligament. ‘The other passes from the spine of the sphenoid
to the lingula and inner margin of the dental foramen (spheno-
mandibular). Between these two ligaments are the internal
maxillary artery and veins, and lower down the auriculotemporal
and inferior dental nerves; internal to the long band is the
internal pterygoid muscle. Between the short internal lateral
and the synovial membrane is a pad of soft elastic connective

126 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

tissue united to the periosteum of the posterior half of the
glenoid fossa; this is compressed or stretched according to
the position of the condyle.

The stylomandibular ligament has nothing to do with this —
articulation; it is a band of cervical fascia connected at one
end by aid of the styloglossus muscle to the styloid process,
and by the other to the angle and posterior border of the
lower jaw. It separates the parotid from the submaxillary
gland.

Nerves of the joint are the auriculotemporal and masseteric
from the inferior maxillary.

Arteries are temporal, the deep auricular, and tympanic
branches of the internal maxillary.

Actions of the joint are protrusion and retraction, elevation
and depression, or a rotation when one side acts. The move-
ments in the superior and inferior compartments are of different
kinds; in the upper the fibrocartilage glides forward and back-
ward, and in the lower the condyle rotates against it on
a transverse axis. Elevation and depression take place on a
transverse axis through the centres of the rami—some say
through the interarticular cartilages. If the depression be
considerable, the condyle also has a gliding motion, carrying
the cartilage with it. Rotary movement to one or other side
takes place on an axis through the opposite condyle. Depres-
sion is produced by the weight of the jaw, platysma, digastric,
mylohyoid, and geniohyoid muscles; elevation by the temporal,
masseter, and internal pterygoid; protrusion by the external
pterygoid, internal pterygoid, and superficial fibers of the
masseter; retraction by the deep fibers of the masseter and
posterior fibers of the temporal. It is a ginglymoarthrodial
joint.

THE ARTICULATIONS OF THE VERTEBRAL COLUMN
WITH THE PELVIS

The ligaments connecting the lumbar vertebra with the
sacrum are the continuation of the ligaments which connect
the processes of the lumbar vertebra with each other. They
are the lumbosacral and iliolumbar ligaments.

The lumbosacral ligament is attached above to the trans-

LIGAMENTS BETWEEN SACRUM AND ISCHIUM 127

verse process of the last lumbar vertebra, in front, passing
down and outward it is attached to the base of the sacrum;
blending with the anterior sacroiliac and iliolumbar ligaments.

The iliolumbar ligament is attached to the tip of the trans-
verse process of the last lumbar vertebra and passes horizontally
outward to be inserted into the crest of the ilium, just in front
of the sacroiliac articulation.

THE ARTICULATIONS OF THE PELVIS

The ligaments connecting the bones of the pelvis with each
other are: (1) Those connecting the sacrum and ilium; (2)
the sacrum and ischium; (3) the sacrum and coccyx; and (4)
between the pubic bones (Gray).

1. Articulation of the Sacrum and Ilium

This is an-amphiarthrodial joint, formed between the lateral
surfaces of the ilium and sacrum. The anterior portion of
each articular facet is covered by a thin plate of hyaline car-
tilage. These are in contact and partially united together by
irregular patches of ‘softer fibrocartilage, and at the upper
and back portion by interosseous fibrous tissue.

The ligaments are the anterior and posterior sacroiliac.

The anterior sacroiliac ligament is attached to the front of
the sacrum and ilium. The posterior sacroiliac ligament
consists of an upper part (short sacroiliac) passing horizontally
from the first and second transverse tubercles on the posterior
surface of the sacrum, to the rough, uneven surface at the
posterior part of the inner surface of the ilium. The lower
part passes obliquely, and is attached to the third tubercle
on the posterior surface of the sacrum and the posterior superior
spine of the ilium; it is sometimes called the oblique sacroiliac
ligament.

2. The Ligaments Passing between the Sacrum and
Ischium

There is no joint. The ligaments are the great and small sacro-
sciatic.

128 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

The great sacrosciatic ligament (posterior) is triangular, and
attached to the posterior inferior spine of the ilium, by its
broad base, to the fourth and fifth transverse processes of the
sacrum, and to the lower part of the lateral margin of that
bone and the coccyx. Then passes obliquely downward,
outward, and forward to the inner margin of the tuberosity
of the ischium. Some of the fibers pass to the inner margin
of the pubic bone (falciform ligament).

This hgament is united to the small sacrosciatic ligament.
Its outer border forms the posterior boundary of the great
sacrosciatic foramen, and below, the posterior boundary of
the lesser sacrosciatic foramen. It gives attachment to some
of the fibers of origin of the gluteus maximus muscle.

The small sacrosciatic ligament (anterior) is shorter and
smaller than the great sacrosciatic ligament. It is attached
by its apex to the spine of the ischium, then passes internally
to be inserted by its base into the lateral margin of the sacrum
and coccyx, anterior to the attachment of the great sacrosciatic
ligament, with which it blends.

3. Articulation of the Sacrum and Coccyx

This is an amphiarthrodial joint, formed by the oval surface
at the base of the sacrum and coccyx. The ligaments are
the anterior and posterior sacrococcygeal, lateral sacrococcygeal,
and interarticular fibrocartilage.

The anterior sacrococcygeal ligament is attached to the
anterior surface of the sacrum and coccyx, blending with the
periosteum. It is a continuation of the anterior common
ligament.

The posterior sacrococcygeal ligament is divided into a
deep and superficial portion. The deep is a continuation of
the posterior common ligament. It arises from the lower
orifice of the sacral canal, and passing downward is inserted
into the posterior surface of the coccyx. It completes the
lower, back part of the sacral canal. The superficial extends
from the middle sacral ridge to the posterior surface of the
coccyx; and encloses, partly, the sacral canal. The lateral sacro-
coccygeal ligament connects the transverse process of the coceyx
to the lower lateral angle of the sacrum. ‘The interarticular fibro-

THE STERNOCLAVICULAR ARTICULATION 129

cartilage is a thin articular disk, smaller than the ones between
the vertebree. It is placed between the adjoining articular
facets of the sacrum and coccyx.

4. The Articulation of the Pubic Bones

It is an amphiarthrodial joint formed by the junction of
the two pubic bones to form the symphysis. The ligaments
are the anterior, posterior, superior, and inferior pubic.

Interpubic disk.—The ligaments pass from the contiguous
surfaces of the bones. ‘The interpubic disk consists of fibro-
cartilage placed between the two articulating surfaces. Each
surface is covered by hyaline cartilage, attached to the bony
surfaces. |

ARTICULATIONS OF THE UPPER EXTREMITY
The Sternoclavicular Articulation

The ligaments are capsular, anterior and posterior sterno-
clavicular, interarticular fibrocartilage; interclavicular and costo-
clavicular.

The capsule for this joint is made up mostly of strengthening
bands; it is weakest at the lower anterior angle. It completely
surrounds the joint. In front a band called the anterior sterno-
clavicular ligament passes from the inner extremity of the
clavicle obliquely down and into the upper part of the manu-
brium; the posterior sternoclavicular ligament passes in a similar
direction, and is related behind with the sternothyroid and
sternohyoid muscles.

The interarticular cartilage is attached above to the upper
and posterior border of the inner extremity of the clavicle,
and below to the junction of the first costal cartilage with the
sternum, and by its circumference to the capsule; thus the
cartilage of the first rib is partly within this joint. Its cir-
cumference is thicker than its centre, which may be perforated;
in size and shape it varies greatly. It lessens the inequalities
of the two bony surfaces, and divides the joint into two parts,
each provided with a synovial membrane. In young bones
the interclavicular notch on the sternum'is covered by hyaline
cartilage.

9

130 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

The interclavicular ligament is a flat band passing in a curved
direction between the inner extremities of the clavicles, and
is closely attached to the upper border of the sternum. Some
of its fibers are connected with the periosteum of the posterior
surface of the sternal end of the clavicle, and some with the
back of the capsule. So if we follow the course of the connec-
tive tissue from the upper border of the clavicle, some goes
to the interarticular cartilage, some to the capsule, and some
forms the interclavicular ligament.

The costoclavicular or rhomboid ligament ascends obliquely
from the inner part of the cartilage of the first rib back to
the depression on the under surface of the sternal end of the
clavicle. To its outer side is the subclavian vein. This lga-
ment encloses the tendon of insertion of the subclavius muscle,
but most of the ligament is behind the muscle, its anterior
part being continued as fascia over it. Between the muscle
and the posterior part of the ligament is sometimes developed
the “bursa of Monro.” Cruveilhier describes this ligament
and bursa as the costoclavicular articulation.

Nerves, second and third cervical by descendens noni.
Arteries, neighboring muscular branches. Motion is not a
gliding, but axial on the fibrocartilage. Elevation and depres-
sion of the shoulder produce movement here on a transverse
axis through the costoclavicular ligament; movement of shoulder
forward and backward, on a vertical axis through the same
point. It is an arthrodial joint.

THE ACROMIOCLAVICULAR ARTICULATION

The acromioclavicular is an arthrodial joint formed by the
outer extremity of the clavicle and the inner margin of the
acromial process of the scapula.

Ligaments are capsular (superior and inferior acromio-
clavicular), interarticular fibrocartilage; coracoclavicular, con-
sisting of the trapezoid and conoid ligaments.

There is a weak capsule to this joint, really a fibrous covering
of the synovial membrane; it is strongest above, being
strengthened above and below by bands designated by some
as the superior and inferior acromioclavicular ligaments. ‘The
interarticular cartilage is usually present in some form, either

THE PROPER LIGAMENTS OF THE SCAPULA 131

hanging from the edge of the clavicle in the upper part of the
joint or covering the whole articular surface of the acromion,
or in 3 out of 400 cases wholly dividing the joint into two
cavities.

The coracoclavicular ligaments connect the clavicle more
firmly with the scapula; there are three. The posterior coraco-
clavicular comprises the trapezoid and conoid. The trapezoid
is external, and attached below to the upper surface of the
coracoid, and above to the oblique line passing forward and
outward on the under surface of the clavicle. Its outer border
is free, and its internal border unites with the conoid, forming
an angle projecting backward. This checks forward move-
ment of the clavicle.

The conoid is posterior and internal, and attached by its
apex to the base of the coracoid, and by an expanded base
to the conoid tubercle and a line internal to it on the under
surface of the clavicle. This checks backward movement of
the clavicle. Between these two ligaments a bursa may be
developed, and between them is also the extremity of the sub-
clavius muscle.

The synovial membrane is usually single, or double when
the interarticular cartilage is complete.

Nerves, suprascapular and _ circumflex. Arteries, supra-
scapular and acromial thoracic. Movements of joint, gliding
and rotation.

THE PROPER LIGAMENTS OF THE SCAPULA

They pass between portions of the scapula, the coracoid
and acromial processes, but are not parts of a joint.

The ligaments are coracoacromial, superior, and inferior
transverse.

The coracoacromial is attached by its apex to the summit
of the acromion, and by the base to the whole length of the
outer border of the coracoid process of the scapula. The
superior transverse ligament is attached to the base of the
coracoid process and the inner margin of the suprascapular
notch. The inferior transverse (spinoglenoid) is attached to
the outer border of the spine and the margin of the glenoid
cavity. It is not always present..

132 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

The Shoulder-joint

The ligaments are capsular, glenoid, coracohumeral, trans-
verse humeral.

This is a ball-and-socket joint, peculiar (1) in the large
size of the head of the humerus and shallowness of the glenoid
cavity; (2) looseness of the capsule; (3) intimate relation of
the muscles with the capsule; (4) relation of the biceps tendon
to the joint. The glenoid articular cartilage is thinnest at
its centre—,% inch (2 mm.).

Fria. 23

) SUPERIOR GLENO-
HUMERAL LIGAMENT

Shoulder-joint, rear view. The hind part of the capsular ligament and most of the
head of the humerus bave been removed. (Testut.)

The capsule encircles the articulation, attached above to.

the margin of the glenoid cavity, beyond the glenoid ligament,
and below to the anatomical neck of the humerus. It allows
the bones to be separated more than an inch; it is strengthened
by tendons of muscles which may be reckoned as ligaments,
viz., above by the supraspinatus and tendon of biceps, externally

THE SHOULDER—JOINT 133

by the infraspinatus and teres minor, below by the long head
of the triceps, and internally by the subscapularis. There
is a weak place in the capsule uncovered by muscle between
the edges of the teres major and subscapularis; vessels and
nerves enter here.

The superficial fibers of the capsule are longitudinal, and.
deeper ones are circular, forming a truncated cone, with its
narrow end toward the scapula. Below are folds in the capsule
which become straight in raising the arm.

The glenoid ligament is a fibrocartilaginous rim attached
to the margin of the glenoid fossa to form a deeper cavity;
it is triangular on section, and ;'; inch (8 mm.) broad at its
base. It is partly formed by the biceps tendon above as it
bifureates at its attachment, and by the triceps below, the
fibers being arranged in concentric rings. Its intrinsic fibers
are fused with the capsule. ;

The synovial membrane lines the capsule and covers the outer
side of the glenoid ligament, and is continued a short distance
over the cartilage on the head of the humerus. The long tendon
of the biceps passing through the capsule is enclosed in a tubular
sheath of synovial membrane, and so does not really enter the
synovial cavity. A rounded protrusion of the synovial mem-
brane, bursa intertubercularis, clothes the upper part of the
bicipital groove as far as the insertion of the pectoralis major
and latissimus dorsi. From within the tube of synovial mem-
brane there passes to the tendon of the biceps a retinaculum
of longitudinal bundles of connective tissue.

The joint cavity communicates with a large’ bursal sac
beneath the subscapularis tendon, and occasionally with that
under the tendon of the infraspinatus muscle.

The deltoid muscle is separated from the capsule by a large
bursa which does not communicate with the joint.

Among the strengthening bands of the capsule is the coraco-
humeral ligament, rising from the outer border of the coracoid,
spreading out upon the upper and posterior wall of the capsule,
and inserted into the great tuberosity of the humerus.

The ligamentum coracoglenoidale is a part of the coraco-
humeral, rising with it and passing backward and outward at
right angles on the surface of the capsule to the upper margin
of the glenoid cavity.

134 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

The transverse humeral ligament is a part of the capsule
between the tuberosities.

When the joint is viewed from the inside, there are three
supplementary bands seen on the anterior part of the capsule.
The highest is the glenoideohumeral or Flood’s ligament, which
passes from the upper part of the anterior margin of the glenoid
cavity to the upper end of the bicipital groove. The middle
band is the internal glenoideobrachiale of Schlemm. It is a
thin fold arising from the same point as the preceding ligament.
It descends obliquely outward to be lost on the capsule beneath
the subscapular tendon, passing to the small tuberosity (Quain).
The lowest band is the ligamentum glenoideobrachiale inferior,
or broad ligament of Schlemm, which rises from the middle
of the anterior margin of the glenoid cavity and passes down
and out parallel to the internal ligament of Schlemm to the
under portion of the neck of the humerus.

The head of the humerus is held in place by the subscapularis,
supraspinatus, infraspinatus, deltoid, biceps, and _ triceps
muscles, and also by atmospheric pressure.

The nerves supplying the joint are circumflex and supra-
scapular.

The arteries are anterior and posterior circumflex and supra-
scapular.

The movements of the joint are in every direction.

Flexion is possible to 45 degrees without involving other
joints, produced by the pectoralis major, anterior fibers of
the deltoid, coracobrachialis, and by the biceps if the elbow
is fixed. ‘This occurs on a transverse axis through the great
tuberosity and glenoid cavity. Flexion is limited by tension
of the posterior part of the capsule and by the small tuberosity
abutting against the coracoid; the movement is continued
by rotation of the scapula.

Extension through 15 degrees is produced by the latissimus
dorsi, teres major, posterior fibers of the deltoid, and the triceps
if the elbow is fixed. Extension is hindered by superior muscles
and approximation of the great tuberosity and acromion.

Abduction through 90 degrees is performed by the deltoid,
aided by the supraspinatus, on an anteroposterior axis through
the anatomical neck of the humerus; further motion calls into
play accessory joints, viz., the upper portion of the trapezius
elevates the peak of the shoulder, and the lower fibers of the

THE ELBOW-—JOINT 135

serratus magnus pull the inferior angle of the scapula forward,
rotating that bone, which raises its external angle. Two other
joints share the motion—the acromioclavicular until its yielding
is stopped by the coracoclavicular ligaments, next the sterno-
clavicular joint until its motion is checked by the costoclavicular
ligament. So three chief muscles are concerned in raising the
hand above the head, and ‘two joints besides the shoulder-
joint. Freest motion is up and forward. The angle between
the scapula and clavicle changes to secure adaptation of the
former to the chest wall.

Adduction is accomplished by the subscapularis, pectoralis
major, latissimus dorsi, and teres major. ‘Total rotation is
through 90 degrees, limited by capsule and muscles; it is freest
-externally and backward; rotation in is produced by the sub-
scapularis, latissimus dorsi, and teres major; rotation out by
the infraspinatus, supraspinatus, and teres minor. Circum-
duction is a combination of all the angular movements in
succession.

The Elbow-joint

The elbow is a hinge-joint formed by the trochlea of the
humerus resting in the greater sigmoid cavity of the ulna;
while the capitellum or radial facet of the humerus articulates
with the lesser sigmoid cavity of the ulna.

The ligaments are capsular, with thickened bands and the
orbicular ligament; the thickened bands are known as anterior
and posterior, internal lateral and external lateral.

The capsule includes the coronoid and part of the olecranon
fossee, a part of the internal epicondyle, but not the external,
the tips of the coronoid and olecranon processes. The anterior
thickened portion of the capsule passes from the point of the
inner epicondyle and from the front of the humerus above
the coronoid fossa to the anterior margins of the coronoid
process, and externally into the orbicular ligament. Super-
ficially is an oblique band passing down and out from the
internal epicondyle to the orbicular ligament. The fibers
under these are vertical, the anterior ligament of Barkow, and
the deepest are transverse. The posterior part of the capsule
passes from the lower end of the humerus, leaving the upper
part of the olecranon fossa exposed to the posterior and external
margins of the olecranon process, a little behind the articular

136 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

surface. ‘The lowest fibers are transverse, bridging over part
of the olecranon fossa; the upper fibers are vertical, thickest
in the median line, and pass through a fatty pad in the upper
part of the fossa. These vertical fibers are Barkow’s posterior
straight cubital ligament; on either side of it the capsule is as
thin as a bursa.

The internal lateral ligament is fan-shaped, rises from the
lower and back part of the root of the inner epicondyle, and
consists of three portions: (1) A posterior humeroolecranon
part, helping form the groove for the ulnar nerve; (2) an anterior
humerocoronoid part; and (8) an olecranocoronoid portion,
deepening the sigmoid cavity.

The external lateral ligament is not so distinct as the internal;
it is attached above to a depression below the external epi-
condyle, and below to the orbicular ligament and to the upper
part of the interosseous border of the ulna (not into the radius,
or its rotation would be impaired). It gives some strengthening
bands to the anterior ligament, forming a cruciform arrange-
ment. ‘The supinator brevis arises from this ligament in part.
The brachialis anticus muscle inserts a band into the anterior
ligament, the triceps a band into the posterior. The anconeus
arises partly from the capsule between the external condyle
and external border of the olecranon.

The orbicular ligament is described under the superior radio-
ulnar articulation.

The synovial membrane is extensive, lines the capsule and
orbicular ligament, and enters into the articulation between
all three bones.

There are inequalities between the sigmoid fossa and trochlea
which are filled in with synovial membrane or fatty pads;
there is another pad in the small sigmoid cavity. The capsule
is reinforced by intracapsular and extracapsular pads, both
in the coronoid and olecranon fosse. This allows free gliding
of muscles. The triceps pulls up the wrinkled capsule in
extension, the brachialis anticus in flexion.

The muscles in relation to the joint are, in front, the brdcltislis
anticus; behind, the triceps and anconeus; externally, the
supinator brevis and supinatoextensor group; internally, the
pronatoflexor group.

The burse related to the joint are: (1) Superficial olecranon
bursa between the tendon of the triceps and the skin; (2) deep

THE ELBOW-JOINT 137

olecranon, Setwoen the tendon of the triceps and the bone;
(3) at the inner margin of the brachialis anticus; (4) bicipital
bursa, between the tendon of the biceps and the bone; (5)
epicondylar bursz, subcutaneous; (6) sometimes a retro-
epitrochlear behind the inner epicondyle, related to the ulnar
nerve.

Nerves are from the ulnar, median, musculospiral, internal
cutaneous, and nerve of Cruveilhier (from the branch of the
musculocutaneous to the biceps).

Arteries are derived from an anastomosis between the inferior
and superior profunda, anastomotica magna, anterior and
posterior ulnar recurrent, interosseous recurrent, and radial
recurrent.

Action.—The bimienoutnas joint possesses flexion and exten-
sion, no lateral movement or rotation.

F lecion of 150 degrees is possible, produced by the supinator
longus, biceps, brachialis anticus, and muscles from the inner
condyle; it is checked by contact of soft parts, posterior part
of the capsule, and posterior part of the internal and external
lateral ligaments, not by bone.

Extension (after flexion) goes through 150 dewrees by the
triceps, anconeus, extensors of the wrist, and common extensors
of the fingers; it is checked by the anterior part of the capsule
and anterior parts of the external and internal lateral liga-
ments, not by bone.

Supination (rotation out) and pronation (rotation in) occur
through 90 degrees in the radioulnar and radiohumeral joints
on an axis through the head and neck of the radius and styloid
process of the ulna. Supination is performed by the biceps
strongly, by the supinator longus and brevis and extensors
of the thumb; pronation by the pronator radii teres and pro-
nator quadratus; in this last motion there is a “winding up”
of the biceps and supinator brevis. These rotary movements
are checked by the oblique ligament, orbicular, and capsular,
by the interosseous membrane, by the inferior articulation,
and by muscles. If sliding of the soft parts on the ulna is
hindered, pronation and supination are largely checked.

138 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

THE RADIOULNAR ARTICULATION

It is divided into superior, middle, and inferior radioulnar
articulations.

The Superior Articulation

This is a trochoid or pivot joint, formed by the inner side
of the head of the radius rotating within the lesser sigmoid
cavity of the ulna.

The orbicular ligament surrounds. the head of the radius;
it forms about + of an osseofibrous ring and is attached to the
lesser sigmoid cavity of the ulna.

The synovial membrane lines the smooth, inner surface,
and is continuous with that which lines the elbow-joint.

The Middle Radioulnar Articulation

The oblique ligament (chorda transversalis) is a flatly rounded
cord running from the tubercle of the ulna on the coronoid
process down and out to a point on the radius a little below
the bicipital tuberosity. Its fibers have an opposite direction
to those of the interosseous ligament. The oblique may be
wanting, or may exist as a tendinous slip to the flexor longus
pollicis; it may be double, the upper band passing from the
small sigmoid notch and orbicular ligament to a point above
the bicipital tuberosity.

The interosseous ligament (membrane) connects the inter-
osseous ridges of the radius and ulna. The fibers pass down
and into the ulna in such a direction that if the hand press
against resistance the radius would drag the ulna after it.
The lgament is divisible here and there into several layers,
some fibers coming from the anterior surface. of the radius.
It is deficient above, commencing on the radius at the insertion
of the oblique ligament, leaving a space between the two for
the posterior interosseous vessels. Just above its lower end
is an oblique opening between two layers of the ligament for
the passage of the anterior interosseous vessels. The lower
edge is almost vertical, the fibers ending higher on the ulna
than on the radius and running in a direction opposite to the

THE RADIOCARPAL OR WRIST-JOINT 139

fibers above; this lowest split between the ligament and ulna
is filled with fat and covered by the pronator quadratus muscle.
Some fibers go to the posterior annular ligament.

The Inferior Radioulnar Articulation

This is a lateral ginglymus joint between the head of the
ulna and sigmoid cavity of the radius.

The ligaments are the anterior and posterior radioulnar and
triangular fibrocartilage ‘The anterior and posterior ligaments
are narrow bands passing transversely over the joint, as indi-
cated by their names.

The triangular ligament is placed beneath the ulna, attached
by its apex to the base of the styloid process; its under surface
articulates with the cuneiform.

The synovial membrane is very extensive, the membrana
sacciformis.

Actions are supination and pronation.

THE ARTICULATIONS OF THE WRIST AND CARPUS
The Radiocarpal or Wrist-joint

This is a condyloid articulation between the radius and
triangular cartilage above, the scaphoid, semilunar, and cunei-
form below.

The ligaments are external and internal lateral, anterior and
posterior. ‘The first two are rounded cords passing respectively
from the styloid process of the radius and ulna to the end
carpal bones of the first row. The anterior ligament is a broad
membranous band connecting the anterior surfaces of the
bones forming the articulation. The posterior ligament is
less strong than the anterior, and passes from the radius to
the dorsum of the first three carpals.

Nerves are from the ulnar and posterior interosseous.

Actions are flexion, extension, abduction, adduction, and
circumduction,

140 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

Fra. 24

» had |
* 9 Na
¥

Vertical section through the articulations at the wrist, showing the five synovial
membranes.

The Ligaments of the Carpus

They are in three sets: (1) articulations of the first row have
two dorsal, two palmar, and two interosseous ligaments; (2)
articulations of the second row have three dorsal, three palmar,
and three interosseous ligaments; (38) articulations of the two rows
with each other have anterior, posterior, external lateral, and
internal lateral ligaments.

The Carpometacarpal Ligaments

The first metacarpal bone and the trapezium have a capsule
and separate synovial membranes. The joints between the

THE HIP-JOINT 141

carpus and four inner metacarpals have dorsal, plantar, and
interosseous ligaments. -

The synovial membranes of all the joints in the carpus and
wrist proper are five in number (Fig. 24).

‘The Remaining Ligaments of the Metacarpus and
Phalanges

Of the metacarpals with each other, there are the dorsal,
palmar, and interosseous ligaments; their digital extremities
are connected by a narrow band, the transverse ligament,
presenting four grooves for tendons.

The metacarpophalangeal articulations have anterior and two
lateral ligaments. The interphalangeal articulations also have
anterior and two lateral ligaments.

Actions are flexion, extension, and very limited abduction,
adduction and circumduction.

ARTICULATIONS OF THE LOWER EXTREMITY
The Hip-joint

It is an enarthrodial or ball-and-socket joint. ‘lhe articular
surface of the head of the femur is more than a hemisphere;
any section of the bony acetabulum through its centre is less
than 180 degrees.

The ligaments are cotyloid, transverse, teres, capsular;
accessory are orbicular zone, iliofemoral, iliotrochanteric, pubo-
femoral, ischiofemoral, and ischiocapsular.

The cotyloid consists of connective tissue arranged circularly;
it is strengthened and fastened to the edge of the acetabulum
by short fibers rising at different points and interlacing at
acute angles. It is prismoid on section, and embraces the
head of the femur so tightly that air does not enter the joint.
Both its sides are covered with synovial membrane. Inferiorly
the cotyloid becomes flat and bridges over the acetabular
notch at the transverse ligament; it turns one surface upward
and one down; one edge looks within and limits a split through
which, enveloped in fat, bloodvessels enter the socket; the
other edges pass uninterruptedly into the cotyloid ligament.

142 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

The articular cartilage of the acetabulum is 2 mm. thick,
a little thinner toward the centre; that on the head of the
femur is thickest at the centre, + inch (4 mm.). The fossa
acetabuli contains a fat pad.

Fig. 25

Hip-joint, showing inverted Y-ligament. (Bigelow.)

The ligamentum teres is misnamed, being neither hgamentous
nor round; it is somewhat triangular. It is planted by its
apex into the fossa on the posterior inferior quadrant of the
‘head of the femur, and rises from the notch and fossa acetabuli.
Unoccupied space around it is filled with synovia. A cross-
section of it discloses an outer firm and an inner loose part;

THE HIP-JOINT 143

it is made up of transverse fibers limited by the transverse
ligament and longitudinal fibers, which arise from the acetabu-
_ lar fossa, and some pass in from the capsule under the transverse
ligament. Its function may be (1) to check movement; (2)
a remnant from lower animals; (3) to carry synovia and vessels
(this is most probable). The motion it checks is a most un-
natural one, viz., is tense, with thigh flexed, adducted, and
rotated in. Sometimes it is a mere synovial fold, and some-
times is wanting.

The capsule springs from the outer surface of the base of
the cotyloid ligament, from the edge of the acetabulum and
margin of the transverse ligament; below it is attached to
the anterior intertrochanteric line and to the back of the neck
of the femur in a line parallel to the posterior intertrochanteric
and about 4 inch above it. The digital fossa is outside the
capsule; it is impossible to have a true extracapsular fracture
of the neck of the femur. At the attachment to bone the
innermost layer of the capsule is reflected in smooth or longi-
tudinal folds (retinacula) up the neck to the articular cartilage
of the head, with which it fuses. This layer of the capsule
lined with epithelium is a thin but firm membrane, seen by the
microscope to be formed of parallel, transverse, or circular
bands; outside this are connective-tissue layers separating it
from the accessory bands.

The accessory ligaments are either circular or longitudinal.
The circular bands form the zona orbicularis, which is most
distinct on the under wall of the capsule, because less covered
here by the longitudinal bands. It occupies the middle third
of the capsule, and continues upon the upper and lower thirds
as transverse or scattering bands of connective tissue.

The accessory longitudinal bands spring from each of the
three bones forming the acetabulum, and are only lacking in
that part of the capsule which rises from the transverse liga-
ment. They go between the circular fibers, over them, or end
in them.

The iliofemoral ligament extends obliquely across the front
of the capsule, attached above to the lower part of the anterior
inferior spine, and from a point behind this, just above the
acetabulum, and below to the whole length of the anterior
intertrochanteric line. It is covered by a fine layer of circular
fibers, and pierced by some fibers of origin of the outer head

144 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

of the rectus femoris. At its insertion it is divided into two
bands—one to the lower part of the line and base of the small
trochanter, and one to the upper part. Sometimes it does
not divide, forming then a triangular barfd. It is called the
inverted Y-ligament of Bigelow and ligament of Bertin. It
is of great importance in maintaining the erect position of
the body, and requires 250 to 750 pounds for its rupture.

Fic. 26

RECT. FEM.

Tleo-fem. ligament

Bursa

Isch, caps. __Z78
ligament. ZX

Pub. fem. ligament

Relation of the muscles to the hip-joint. (Henle.)

The iliotrochanteric ligament rises from beneath the anterior
inferior spine, and may be considered as the upper arm of the
Y-ligament or as fibers parallel to it, and inserted into the
anterior part of the base of the great trochanter. —

THE HIP-JOINT 145

The pubofemoral ligament may be described in three parts
at its origin: The first is a continuation of the fascia over
the pectineus muscle, and goes from the iliopectineal eminence
_down between the iliopsoas and pectineus muscles to the
lowest part of the capsule; a second fasciculus (pubofemoral
of Barkow) comes beneath the pectineus from the whole length
of the obturator crest, and joins the first set outside that muscle;
a third set comes from the upper ramus of the pubis and upper
obturator spine and joins the others; it gives origin to some
fibers of the obturator externus.

The ischiocapsular ligament rises from the lower part of
the edge of the acetabulum and neighboring portion of the
ischium, and ends in the lower and outer portion of the orbicular
zone.

The <wschiofemoral ligament (Macalister) rises from the
upper part of the ischial tuberosity, passes over the groove
between this tuberosity and the acetabulum, and is attached
to the back of the neck at a point midway between the two
trochanters. It is often fused with the capsule.

Synovial processes occupy the joint outside the fatty pad of
the fossa acetabuli and in the region of the neck of the femur;
broad flaps hang from the capsular covering of the neck, or
thin tufts give a velvety appearance to the inner surface of
the capsule.

The iliopsoas bursa opens into the joint anteriorly, and is
analogous to the subscapular bursa of the shoulder; it may act
as an accessory pouch for synovial supply as needed. Where
the capsule is thin, muscles strengthen it; in front is the ilio-
psoas; above, the rectus and gluteus minimus; internally, the
obturator externus and pectineus; behind, the pyriformis, two
obturators, two gemelli, and quadratus femoris.

Nerves are from the sacral plexus, great sciatic, nerve to
quadratus femoris muscle, obturator, accessory obturator,
and anterior crural.

The arteries are from the obturator, sciatic, gluteal, internal
and external circumflex.

Movements are in every possible direction. Flexion and
extension pass through 139 degrees on the dead subject, about
86 degrees on the living; abduction or adduction through 90
degrees, and rotation through 51 degrees. Flexion is checked
by soft parts and by hamstring muscles (with knee extended),

10

146 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

by posterior part of the capsule and the ischiocapsular ligament;
extension is checked by the anterior part of the capsule and the
iliofemoral ligament; rotation out, by the upper arm of the
iliofemoral; rotation in, by the ischiocapsular and ischiofemoral
ligaments; abduction, by the pubofemoral ligament and the
lower and inner parts of the capsule and impact of the head
of the femur; adduction, by the upper arm of the Y-ligament,
by the iliotrochanteric ligament, and by soft parts.

Iliofemoral ligament checks extension and tendeney to tip
backward, rotation out, and adduction. Pwbofemoral checks
abduction. Ischiofemoral checks rotation in, extraordinary
flexion.

The Knee-joint

This is a double condylar joint, really consisting of three
articulations, one between each condyle and the tibia, one
between the patella and femur which is partly arthrodial.
The ligamentum mucosum indicates the original separation
of the synovial sac into two.

The bones are covered by hyaline cartilage to the average
depth of { inch (4 mm.). On the anterior part of the condylar
surface is a transverse groove caused by indentation of the
fibrocartilages; the part above this groove articulates with
the patella.

The ligaments are: Capsular, anterior or ligamentum patelle,
posterior, internal lateral, two short external lateral, anterior or
external crucial, posterior or internal crucial, two semilunar
fibrocartilages, transverse, and coronary.

The capsular ligament consists of thin but strong fibrous
membrane, which is strengthened by heavy bands, inseparately
connected with it. In front it blends with and forms part
of the lateral patellar ligaments and fills in the space between
the anterior and lateral ligaments, blending with them. Above
it is deficient. Behind it the fibers are mostly vertical, and
are attached above to the condyles and intercondyloid notch
of the femur; below they are attached to the posterior part
of the head of the tibia, uniting with the origins of the gastroc-
nemius, plantaris, and popliteus muscles. It is connected to
the posterior ligament.

THE KNEE-JOINT 147

The anterior or ligamentum patelle is the central portion
of the common tendon of the extensor muscles of the thigh.
It is a strong, ligamentous band, about three inches long,
attached above to the apex and the rough posterior surface
of the patella; below, to the lower part of the tubercle of the
tibia. The lateral portions of the extensor tendon blends
with the fascia later to form the lateral patellar ligaments. The
posterior surface is separated above from the synovial mem-
brane by a fold of fat; below, a synovial bursa separates it
from the tibia.

The posterior ligament is a broad, flat band attached above
to the upper margin of the intercondyloid notch of the femur;
below, to the posterior margin of the head of the tibia. Passing
superficially, from the back part of the inner tuberosity of the
tibia, obliquely upward and outward to the posterior part
of the outer condyle of the femur, is the strong fasciculus
derived from the tendon of the semimembranosis. This is
called the posterior ligament of Winslow. It blends with the
posterior and internal lateral ligaments.

The internal lateral ligament is a broad, flat, membranous
band, attached above to the internal tuberosity of the femur;
below, to the inner tuberosity and surface of the tibia to the
extent of about two inches. It is crossed at its lower part
by the tendons, from before backward, of the sartorius, gracilis,
and semimembranosus muscles. The external lateral ligaments
are divided into long and short external lateral ligaments.
The long external lateral arises from the external tuberosity
of the femur and passes to the head of the fibula. Its outer
surface is in relation with the tendon of the biceps femoris
muscle, which it splits.

The short external lateral is attached above to the back part
of the external tuberosity of the femur, and behind and running
parallel with the long external lateral ligament is inserted
into the styloid process of the fibula. The popliteus muscle
and the inferior external articular. vessels and nerves pass
beneath both the long and short ligaments.

The crucial ligaments are two interosseous ligaments found
within the intercondyloid portion of the joint—the anterior
or external and posterior or internal arcuate ligaments.

The anterior or external is attached to the depression in

148 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

front of the spine of the tibia and the external semilunar car-
tilage, and passes obliquely upward, backward, and outward to
be inserted into the inner and back part of the intercondyle of
the femur.

The posterior or internal is attached to the depression behind
the spine of the tibia, to the popliteal notch, and to the external
semilunar cartilage; passing upward, forward, and inward it is
inserted into the outer and forepart of the internal condyle
of the femur. It is in relation with the anterior ligament in
front; the capsule, behind. These two ligaments cross each
other to resemble the letter X.

The semilunar fibrocartilages are two in number—internal
and external. They are lamelle which serve to deepen the
articular surfaces of the head of the tibia for the condyles of
the femur. They rest on the head of the tibia; their upper
concave surfaces are in relation with the condyles, except
at the inner third, where they blend with the crucial ligaments;
their outer surfaces are convex, and attached to the inner
surface of the capsular ligament.

The internal semilunar fibrocartilage is nearly a semicircle,
is broader behind than in front; its anterior, thin extremity
is attached to the depression on the anterior margin of the
tibia, in front of the anterior crucial ligaments; its posterior
extremity is attached to the depression behind the spine of
the tibia and the posterior crucial ligament. The external
semilunar fibrocartilage forms nearly an entire circle. The
anterior extremity is attached in front of the spine of the
tibia and behind and external to the anterior crucial ligament,
with which it blends; the posterior extremity is attached behind
the spine of the tibia, anterior to the posterior extremity of
the internal cartilage. This cartilage gives off a strong fas-
ciculus, the ligament of Wrisberg, which passes upward and
outward to the inner condyle of the femur.

The transverse ligament passes between the anterior margins
of the internal and external cartilages; sometimes it is absent.

The coronary ligaments connect the cartilages with the
margins of the head of the tibia. They are essentially por-
tions of the capsular ligament.

THE KNEE-JOINT 149
The Burse related to the Joints are arranged as follows:

I. Anterior Burse

PREPATELLAR PRETIBIAL

1. Subcutaneous. 1. One in front of the
. tubercle of the tibia.

2. Subfascial. 2. One between the liga-

mentum patelle and_ the
tubercle of the tibia.

3. Subaponeurotic. 3. Subpatellar. |
TT. Suberural Bursa
III. Lateral Burse
EXTERNALLY INTERNALLY
1. Beneath the outer head 1. Beneath the inner head
of the gastrocnemius. of the gastrocnemius.
2. Beneath the tendon of 2. Beneath the semimem-
the popliteus. branosus.
3. Between the tendon of '3. Between the semimem-

the popliteus and the external _branosus and semitendinosus.
* lateral ligament.
4. Bicipital, between the
biceps, fibula, and external
lateral ligament.

The nerves are from the obturator, anterior crural, by
branches to the vastus externus, internus, and crureus, external
and internal popliteal, three branches from each, and some-
times the great sciatic.

The arteries are: The anastomotica magna of the femoral,
five articular of the popliteal, anterior tibial recurrent, posterior
tibial recurrent, and a descending branch from the external
circumflex,

Movements to be considered are those between each condyle
and tibia, between the femur and patella. It is a hinge, and
owes its special motions to pecypliarity of ligaments rather
than to conformation of bone, as in the case of the elbow.
Flexion and extension have a maximum of 140 degrees; flexion

150 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

is arrested mostly by the anterior crucial ligament; the anterior
fibers of the posterior ligament are also stretched. At the
beginning of flexion both crucial ligaments become relaxed;
both are stretched in extension, especially the posterior short
fibers of the posterior crucial. In extension the lateral liga-
ments are tense, and do not allow any motion but flexion.
Flexion and extension do not occur in a purely hinge-like
manner; the same part of one articular surface is not always
applied to the same part of another; the axis of motion is
not a fixed one. The motion of the femur on the tibia is likened
to that of a carriage wheel on the ground; it advances or recedes
while it rotates.

The semilunar cartilages are loosely attached, and move
forward in extension and backward in flexion of the joint
like movable wedges; as the condyles roll and present different
curvatures, each cartilage contracts or expands to fit the surface
above. ‘The actual contact of the femur with the tibia is hardly
more than linear.

In extension the anterior capsular wall is raised by the
subcrural muscle; in flexion the posterior wall has two muscles
to prevent its bulging into the joint. The semimembranosus
acts through its oblique ligament when the flexors from the
thigh and pelvis are in operation; the popliteus, through the
arcuate ligament when the plantaris and those attached to
the os calcis act.

As flexion increases, rotation is possible, and increases to
a total of 39 degrees, due to a relaxation of the lateral and —
crucial ligaments. Rotation out (supination) is most extensive,
as the external lateral ligaments are more loose than the internal;
this occurs on an axis through the inner condyle and inner
tuberosity of the tibia. This motion is checked by the internal
lateral ligament and the winding of the posterior crucial around
the spine of the tibia. Rotation in (pronation) on an axis
through the outer condyle and outer tuberosity of the tibia
is never more than 5 to 10 degrees; this motion is checked by
the anterior crucial ligament and by the twisting of these
crucial ligaments around each other.

At the close of full extension there is a movement of adapta-
tion, or gliding back of the inner condyle upon the tibia; this
axis is through the external condyle. At the beginning of
flexion a reverse motion takes place.

THE UPPER TIBIOFIBULAR ARTICULATION 1051

The movements of the patella are partly gliding and partly
those of eoaptation. In extension only the lower sixth of the
patellar articular surface is in contact with the femur; in semi-
flexion, the middle three-sixths; in full flexion, the upper two-
sixths, as the ligamentum patelle pulls it down in front of
the joint.

The Synovial Membrane.—It encloses the articular cavity of
the knee-joint. It is the largest and most extensive synovial
membrane in the body, consisting of a cul-de-sac beneath
the quadriceps extensor tendon, which communicates by a
small orifice with a synovial bursa between the patella and
femur (bursa subpatellaris). It extends beneath the vastus
internus and externus muscles, and is separated from the
anterior ligament by the capsule and adipose tissue (infra-
patellar pad). In this region it gives off a triangular pro-
longation containing a few ligamentous fibers, the ligamentum
mucosum, which extends from below the patella to the inter-
condyloid notch; the latter gives off two thin folds, ligamen-
tum alaria, which extend laterally between the femur and
patella. The membrane covers the internal surfaces of the
ligaments, surrounds the crucial ligaments and cartilages. The
portion between the quadriceps extensor muscle and the femur
is supported during the movements of the knee by the sub-
crureus muscle, which is inserted into the upper part of the
capsular ligament. It forms a cul-de-sac between the groove
on va back of the external semilunar cartilage and the popliteus
muscle.

THE LIGAMENTS BETWEEN THE BONES OF THE LEG

The Upper Tibiofibular Articulation

The capsule rises from the tibia about + inch (5 mm.) above
the articular surface, elsewhere from its edge; it passes to the
contiguous margins of the fibular surface, and generally en-
closes a little space at the lower part of the joint, covered
weed by periosteum, where the tibia and fibula rest upon each
other.

Accessory bands are anterior and posterior ligaments (liga-
menta capituli fibule anteria et posteria). The former consists
of one or more bands from the front of the head of the fibula

152. ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

to the front of the outer tuberosity of the tibia; some fibers
of the peroneus longus and extensor longus digitorum arise
from it. The posterior ligament connects the bones in a similar
manner, and is covered by one head of the soleus. This joint
cavity may communicate with the knee-joint. Fat fills the
space between the capsule and interosseous membrane.

The joint surfaces move in a transverse and sagittal direc-
tion, more in the former; the purpose of the movement is
to allow a gliding at the lower ends of the bones. This is an
arthrodial joint.

The Interosseous Membrane

Between the bones is the interosseous ligament or membrane,
its fibers passing down and out to the fibula; it separates the
flexor from the extensor muscles. Above is an opening for
the anterior tibial vessels, and below another for the anterior
peroneal. Close to the upper tibiofibular joint is a band of
fibers analogous to the oblique ligament of the forearm, running
in a direction opposite to that of the fibers of the rest of the
membrane. If the forearm be pronated and compared with
the leg, the two interosseous ligaments run in parallel directions.

The Inferior Tibiofibular Joint

The inferior tibiofibular joint presents interosseous, anterior,
posterior, and transverse ligaments. The interosseous is con-
tinuous with the interosseous membrane above. The anterior
and posterior ligaments connect corresponding surfaces of the
two bones. The transverse is under the posterior ligament,
projects below and connects the margins of the bones, and
forms part of the articulating surface for the astragalus. This
is an arthrodial joint.

The Ankle-joint

The tibiotarsal articulation is a ginglymus, or hinge joint,
formed by the lower extremity of the tibia and its malleolus
and the external malleolus of the fibula, the former articulating
with the upper convex surface and internal articular facet of
the astragalus; the latter, with the external articular facet of the
astragalus.

THE ARTICULATIONS OF THE TARSUS 153

The ligaments are anterior tibiotarasl, posterior tibiotarsal,
internal lateral, and external lateral.

The anterior is broad and thin, and connects the tibia and
astragalus. The posterior consists mostly of transverse fibers
between the tibia and astragalus.

The internal lateral, or deltoid, has a superficial and a deep
layer; the former rises from the apex, anterior and posterior
borders of the internal malleolus, and passes forward to the
scaphoid and inferior caleaneoscaphoid ligament, downward to
the posterior edge of the sustentaculum tali, and backward
to the astragalus, all to different bones; the deep layer is strong
-and thick, and passes from the apex of the malleolus directly
to the inner surface of the astragalus.

The external lateral ligament has three fasciculi—one from
the anterior part of the external malleolus to the astragalus,
a middle one from the apex of the malleolus to the os calcis,
and a posterior one from the back of the malleolus to the
astragalus.

THE ARTICULATIONS OF THE TARSUS

The calcaneoastragaloid articulation is an arthrodial joint,
formed by the astragalus and os calcis connected by a capsule
which is thickened at certain points, forming five ligaments—
internal and external calcaneoastragaloid, anterior and posterior
calcaneoastragaloid, and interosseous.

The articulation of the os calcis with the cuboid is an arthrodial
joint, the two surfaces being connected by four ligaments—
superior or dorsal calcaneocuboid, internal calcaneocuboid, two
plantar, divided into long and short calcaneocuboid.

The superior connects the upper surfaces of the two bones.

The internal is somewhat interosseous, blending with the
superior calcaneoscaphoid ligament.

The long plantar or calcaneocuboid is the longest of all the
ligaments of the tarsus; it is attached to the under surface
of the os caleis, from near the tuberosities, as far as the anterior
tubercle; its fibers passing forward to be attached to the ridge
on the under surface of the cuboid bone, some of the more
superficial fibers passing to the second, third, and fourth meta-
tarsal bones. .

This ligament passes over the groove on the under surface

154 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS

of the cuboid bone, converting it into a canal for the tendon
of the peroneus longus.

The short plantar or calcaneocuboid’extends from the anterior
tubercle of the os calcis to the cuboid bone behind its peroneal
groove.

The Articulation of the Os Calcis and Scaphoid.—These bones
do not, as a rule, articulate; the ligaments are superior or
external calcaneoscaphoid, inferior or internal calcaneoscaphoid.
The superior ligament blends with the internal caleaneocuboid
ligament to form the ligamentum bifurcatum.

The articulation of the astragalus with the scaphoid is an
arthrodial joint; the only ligament is the superior astragalo-
scaphoid.

The following tarsal articulations are connected by dorsal,
plantar, and interosseous ligaments—the scaphoid with the
three cuneiform bones; the scaphoid with the cuboid; the
cuneiform bones with each other; the external cuneiform with
the cuboid.

Synovial Membranes.—The calcaneoastragaloid articulation has
two—one for the posterior calcaneoastragaloid articulation,
another for the anterior calcaneoastragaloid articulation;
the latter synovial membrane is continued forward between
the contiguous surfaces of the astragalus and scaphoid bones. -
The calcaneocuboid ligaments are lined with a distinct mem-
brane. The astragalus and scaphoid bones are lined by a mem-
brane continued forward from the caleaneoastragaloid articula-
tion. The following tarsal joints and their ligaments are
lined with a membrane which is part of the great tarsal synovial
membrane—the scaphoid with the cuneiform bones; the
scaphoid with the cuboid; the cuneiform bones with each
other; the external cuneiform bone with the cuboid.

The Remaining Ligaments of the Foot

The tarsometatarsal joints have dorsal, plantar, and inter-
osseous ligaments; the latter are three in number.,

The intermetatarsal articulations have dorsal, plantar, and
interosseous ligaments; the digital extremities are united by a
transverse metatarsal ligament which connects the great toe to
the others.

Metatarsophalangeal and interphalangeal articulations have
each plantar and two lateral ligaments.

QUESTIONS ON ARTHROLOGY

THE ARTICULATIONS OF THE TRUNK AND HEAD

What are the ligaments of the vertebrae?

Name and describe the special ligaments of the rotation vertebra.
Name and describe the ligaments binding the ribs to the vertebre.
Describe the temporomaxillary articulation.

THE ARTICULATIONS OF THE UPPER EXTREMITY

How many synovial sacs are there in the sternoclavicular and
sternoacromial joints?

What are the ligaments of the shoulder-joint?

Is the shoulder-capsule taut or lax?

What are the strengthening bands of the shoulder-capsule?

Is the long tendon of the biceps within the shoulder synovial cavity?

What bursz communicate with the shoulder-joint’s synovial cavity?

Name the tendons in relation to the shoulder-joint, stating the
relation of each.

To what is the external lateral ligament of the elbow attached below?

To what part of the olecranon process is the outer portion of the
posterior ligament of the elbow attached?

What are the ligaments of the wrist?

THE ARTICULATIONS OF THE LOWER EXTREMITY

What are the ligaments of the hip-joint?

Where is the capsule of the hip-joint attached to the femur?

Describe fully Bigelow’s inverted Y-ligament.

Give the relations of tendons and muscles to the hip-joint.

Mention what limits the various motions at the hip-joint.

To what degree is extension possible at the hip?

What are the internal ligaments of the knee-joint? What the
external?

Describe the posterior oblique fasciculus, the crucial ligaments, the
semilunar cartilages, and the ligamentum mucosum

What relation does the popliteus tendon bear to the external lateral
lateral ligaments?

What are the fasciculi of the external lateral ligament of the ankle?

Describe the deltoid ligament.

Paw EE

MYOLOGY, OR THE ANATOMY OF THE
MUSCULAR SYSTEM

THE MUSCLES IN GENERAL

Myology is the branch of anatomy which treats of the muscles.
Muscles are divided into voluntary striated, under the control
of the will; involuntary non-striated, not under the control
of the will. Between these two groups we have the cardiac
muscle, which is an involuntary striated muscle.

In the description of a muscle is included the origin, mean-
ing its more fixed point or central attachment; and the insertion,
the movable point to which the force of the muscle is exerted.

THE FASCIA IN GENERAL

These fibrous structures are arranged in two layers, super-
ficial and deep, each with its subdivisions.

The superficial fascia is subcutaneous all over the body;
its web contains subcutaneous fat, the panniculus adiposus,
and often superficial muscles, the panniculus carnosus. ‘There
is no fat in this layer in the eyelids, penis, and scrotum. Be-
neath the fatty layer is usually another, devoid of fat, for the
support of vessels and nerves.

The deep fascie or aponeuroses are made of strong fibrous
tissue covering the body more or less, forming aponeuroses of
investment or of insertion for muscles. Near some joints it
is strengthened by transverse bands, forming retinacula or
annular ligaments to hold tendons close to bones.

156 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

Tendons are pearl-colored, fibrous cords, differing in length
and thickness; they are round or flat, of considerable strength,
and devoid of elasticity. Their structure consists of fibrils
of white fibrous tissue which run in an undulating parallel
course. Very few arteries or veins are found in the tendons.

THE MUSCLES AND FASCIZ OF THE NECK

The neck muscles are mostly vertical, a superficial or anterior
group, somewhat resembling the recti abdominis; a deep or
posterior group corresponding to the intercostals and serratus
anticus.

I. THE ANTERIOR NECK MUSCLES

Long Muscles.—1. Platysma myoides (M. subcutaneus colli)
is a pale thin muscular sheet over the front and side of the
neck and lower part of the face. Origin, the skin and sub-
cutaneous tissue over the deltoid, pectoral, and trapezius
muscles in a line from the anterior end of the second rib to
the acromion; fibers pass up and in over the clavicle, and are
inserted into the lower jaw; the two muscles meet at the hyoid,
and the right overlaps the left one; the posterior fibers blend
with the depressor anguli and orbicularis muscles and fasciz.
The muscle does not rise from bone; but is inserted into bone,
muscle, and fascia.

Nerves.—Inframaxillary branch of the facial, but as this
unites with the superficial cervical nerve, it may get some
spinal innervation.

Action.—Draws angle of the mouth down and out; may
depress the lower jaw; being curved, it tends to redress itself,
carries skin of the neck forward, and is said to be useful in
singing by removing pressure from the great vessels; used in
swallowing and expressing sudden terror; some authorities say
propels saliva from the parotid.

The Deep Cervical Fascia (Anteriorly)

This passes from the trapezius muscle beneath the platysma
over the posterior triangle of the neck, invests the sterno-
mastoid, and passes over the anterior triangle to the median
line. It is attached below to the clavicle, and perforated by

THE DEEP CERVICAL FASCIA 157

the external jugular vein; attached above to the lower jaw,
and becomes the parotid fascia and stylomandibular ligament.
In front it is attached to the hyoid bone, and splits below the
thyroid gland; the anterior layer goes to the anterior surface

Wf

: wh
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yf Ml
A

A " Y)

Muscles of the neck and boundaries of the triangles.

of the sternum, and the posterior, covering the sternohyoid
and thyroid muscles, is attached to the interclavicular ligament;
between these two layers is the swprasternal space, extending
a short distance on either side behind the sternomastoid as
the supraclavicular recess. Prolonged from the deeper layer,

158 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

a fascia invests the posterior belly of the omohyoid and holds
it down to the first rib, there connected with the costocoracoid
membrane. A process (pretracheal portion) also passes behind
the depressors of the hyoid, invests the thyroid body, passes
to the trachea, forms the carotid sheath, and extends to the
pericardium. Deepest of all is the prevertebral fascia. Inside
the pharyngeal muscles is the pharyngeal aponeurosis, outside
them their proper fascial layer (buccopharyngeal), connected
to the prevertebral fascia by areolar tissue, forming the retro-
pharyngeal space. A prolongation of the prevertebral fascia
forms the avillary sheath.

2. M. Sternocleidomastoideus (its full name should penton
its insertion into the occipital bone).—Origin, sternal head,
thick and round, from anterior surface of the manubHeiis.
clavicular, from the inner third of the upper surface of the
clavicle. The two portions meet, pass up and back, and insert
into the anterior border and outer surface of the mastoid
and outer half or more of the superior curved line of the
occiput, to meet the trapezius. Spinal accessory nerve pierces
the under surface of the external portion.

Nerves.—Both by the spinal accessory, offsets of which
are joined by the second cervical.

Actions.—The two sternomastoids draw the head and neck
forward toward the sternum; one, acting slightly, flexes the
head (extends, Henle) and flexes laterally and rotates, so
that the face looks up and toward the opposite side. Fixed
above, the muscles elevate the thorax in forced inspiration.

3. Digastriec muscle (M. biventer mandibule) has two bellies
united by a rounded tendon; the posterior belly rises from
the digastric fossa on the mastoid portion of the temporal
bone, passes down, in, and forward toward the hyoid bone.
The anterior belly is attached close to the symphysis of the
lower jaw, on its inner surface close to the inferior margin,
and directed down, back, and slightly outward; the inter-
vening tendon is attached to the body and great cornu of
the hyoid by an aponeurosis and by the stylohyoid muscle,
which is pierced by the digastric tendon. The anterior bellies
of the two muscles are connected by a dense aponeurosis.

Nerves.—Anterior belly by the mylohyoid branch of the
inferior dental from the third division of the fifth nerve; pos-
terior belly by the facial.

ee

THE HYOID BONE MUSCLES 159

Actions.—Either an elevator of the hyoid or depressor of
the lower jaw, according to which is fixed; its insertion is not
close enough to the hyoid to allow independent action of either
belly.

The Hyoid Bone Muscles

1. BETWEEN THE BASE OF THE SKULL AND THE Hyorp.—
M. Stylohyoideus—Origin, by narrow tendon from the back
of the styloid process near its root; insertion, usually divided
for transmission of the digastric tendon, and the two portions
pass ununited to the hyoid at the junction of the great cornu
and body; almost always a slip ends in the digastric tendon.

May be wanting, may be double; inserted into the digastric
tendon; fibers continued to the omohyoid, thyrohyoid, or
mylohyoid muscles. M. stylohyoideus alter (stylochondro-
hyoideus or stylohyoideus profundus), from styloid process
to the small cornu, accompanying or replacing the stylohyoid
ligament.

Il. Between THE THORAX AND THE Hyorp.—First Layer.—
1. M. Sternohyoideus.— Origin, posterior surface of manu-
brium sterni and sternoclavicular joint, or from joint and
clavicle, from clavicle only, sometimes from the first costal
cartilage; insertion, inner half of the lower border of the hyoid
body. Its inner border approaches its fellow; are far apart
below.

2. M. omohyoideus, ribbon-shaped, has two bellies and an
intermediate tendon. Origin, upper border of the scapula
near the notch or from, the transverse ligament; passes forward
under the trapezius across the scaleni, beneath the sterno-
mastoid, then vertically to the lower border of the hyoid, -
partly beneath and partly in front of the sternohyoid insertion.
Its tendon beneath the sternomastoid at the level of the cricoid
cartilage is enclosed in the deep cervical fascia, which is pro-
longed down to the sternum and first costal cartilage, while
the fascia investing its posterior belly descends to the clavicle.

Second Layer.—1. M. sternothyroideus lies behind the sterno-
hyoid, and rises from the posterior surface of the manubrium
internal to the sternohyoid, variably from the first and second
costal cartilages, diverges from its fellow; inserted into the
oblique line of the thyroid cartilage, covering some fibers of
the inferior constrictor.

160 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

Ill. MuscLes BETWEEN THE LOWER JAW AND THE Hyorp
BoneE.—First Layer.—M. Mylohyoideus.—Origin, from the mylo-
hyoid ridge of the lower jaw, extending from the last molar
tooth nearly to the symphysis; fibers pass inward, back, and
downward, the larger number into the median raphe between
the two muscles which extends from near the symphysis to
the hyoid, hinder ones to the body of the hyoid, on the lower
part of the anterior surface; the posterior border is free; the
two muscles form the “diaphragm of the mouth.”’

Second Layer.— MM. geniohyoideus has a narrow origin from
the inferior mental spine; fibers pass straight back to the
anterior surface of the body of the hyoid, and frequently send
a small slip to the small cornu over the hyoglossus or another
to the great cornu. It may be blended with its fellow or
doubled.

Nerves.—Stylohyoid by facial, mylohyoid by mylohyoid
branch of the inferior dental of the third division of the fifth;
all the others of this group attached to the hyoid bone appar-
ently by the hypoglossal, but really by the first, second, and
third cervical nerves via the communicans or ansa and descend-
ens hypoglossi. }

Actions.—Sternohyoid and omohyoid depress the hyoid bone;
the sternothyroid depresses that cartilage, may make the vocal
cords tense, but with the thyrohyoid depresses the hyoid bone;
the latter also draws up the larynx; may relax the vocal cords,
and produces descent of the epiglottis. ‘These muscles restore
the larynx and hyoid after the act of swallowing, and depress
them in utterance of low tones. The infrahyoid muscles may
act in forced inspiration.

The mylohyoid and geniohyoid elevate the hyoid and draw
it forward, or depress the lower jaw, depending upon which
is fixed; the former raises the floor of the mouth and forces
food back. The stylohyoid acts only on the hyoid bone; aided
by the middle constrictor, it draws it up and back.

The Muscles of the Tongue

M. geniohyoglossus, fan-shaped, is placed vertically in con-
tact with its fellow. Origin, superior mental tubercle; its
lower fibers pass to the superior surface of the body of the
hyoid and side of the pharynx, the superior to the tip of the

THE MUSCLES OF THE PHARYNX 161

tongue, and the intermediate to the whole length of the tongue,
some decussating across the median line.

M. hyoglossus is flat and quadrate. Origin, whole length
of the great cornu and lateral part of the anterior surface of
the hyoid body; insertion, posterior half of the tongue, where
fibers spread forward and inward over the dorsum, joining
the styloglossus. The fibers from the hyoid body may be
called the basioglossus, those from the great cornu the kerato-
glossus.

The chondroglossus is often described as a part of the above,
but is separated from it by the pharyngeal fibers of the genio-
hyoglossus. Origin, inner side of the base of the small cornu
and from part of the superior surface of the hyoid body; its
fibers end on the dorsum of the tongue near the middle line.

M. Styloglossus—Origin, front of the styloid process near
the apex, and largely from the stylomaxillary ligament; insertion,
side and under part of the tongue as far as the tip, decussating
and blending with the hyoglossus and palatoglossus.

The lingualis is the intrinsic tongue muscle, presenting
inferior, superior, transverse, and vertical fibers, with a median
fibrous septum.

Nerves.—Motor supply by the hypoglossal.

Actions.—Geniohyoglossus, hinder part protrudes the tongue,
front part retracts, middle part or nearly whole muscle depresses
and makes dorsum concave; in hemiplegia the sound fibers
push apex over to the paralyzed side. The hyoglossus and
chondroglossus retract, depress, and make the dorsum convex;
the styloglossus draws the tongue back, elevates the base, and
makes the dorsum concave.

The Muscles of the Pharynx

There are two layers—an outer, called the constrictors,
three in number, with a transverse direction; an inner, called
the elevators, two in number, with a longitudinal direction.

Inferior Constrictor (laryngopharyngeus).—Origin, cricoid
cartilage at the lower and back part, the inferior cornu, oblique
line, and upper tubercle of the thyroid cartilage; some fibers
continue into it from the sternothyroid and cricothyroid muscles.
It unites with its fellow in the median line; its inferior fibers
are horizontal, and a few enter the longitudinal layer of the

11

162 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

esophagus, and the highest end on a raphe about 1 inch below
the basilar process. Superficial fibers of one side become deep
in the other, or may join the fibers of another constrictor.
This covers the middle constrictor; the superior laryngeal

Fia, 28

Muscies of the pharynx. External view.

nerve and vessels enter the larynx above its upper border,
and the inferior nerve and vessels beneath its lower border.

Middle Constrictor (hyopharyngeus).—Origin, large and
small cornua of hyoid, from the stylohyoid ligament; fibers
diverge greatly, covering nearly the whole length of the pharynx,

*

”

THE MUSCLES OF THE PHARYNX 163

and meet behind in the median line; the lowest are beneath

the inferior constrictor, the highest overlap the superior con-
strictor, the intermediate ones are transverse. The stylo-
pharyngeus muscle separates this from ‘the superior constrictor.
_ Fibers may come from the hyoid body, tongue, or mylohyoid
ridge; a frequent slip from the lateral thyrohyoid ligament
is the M. syndesmopharyngeus.

Superior Constrictor (cephalopharyngeus).—Origin, side of the
tongue, mucous membrane of the mouth, alveolus at the end
of the mylohyoid ridge, pterygomaxillary ligament, hamular
process, and lower third of the posterior margin of the internal
pterygoid plate; the fibers curve back and insert by blending
with the opposite muscle or end in the aponeurosis which
fixes the pharynx to the basilar process. Of all the constrictors,
only the upper half of this muscle ends in a raphe (linea alba).
The upper margin curves around the levator palati and Eus-
tachian tube; the space intervening, closed by fibrous membrane
is the sinus of Morgagni.

These muscles are covered externally by dense connective
tissue, which is prolonged forward to the pterygomaxillary
ligament, and is continuous with the membrane over the
buccinator muscle; hence it is called the buccopharyngeal fascia.
Next come the muscular layers, next the pharyngeal aponeu-
rosis, and next the mucous membrane.

The M. stylopharyngeus rises from the inner surface of the
styloid process near the root, passes down and in under cover
of the middle constrictor, joined by the palatopharyngeus,
and ends on the superior and posterior borders of the thyroid
cartilage and lateral wall of the pharynx.

The M. palatopharyngeus will be described with the palatal
muscles.

Varieties.—Splitting or doubling or a division into three
parts; supernumerary elevators are common, passing to the
constrictors or fibrous wall of the pharynx; from the petrous
portion or vaginal process = petropharyngeus, from the spine
of the sphenoid = sphenopharyngeus, from the hamular pro-
cess = pterygopharyngeus externus, from the basilar process =
occipitopharyngeus, from the mastoid process (rare) = pharyngo-
mastoideus; a small slip to the raphe from the pharyngeal
spine = azygospharyngeus.

\

164 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

Nerves.—Pharyngeal plexus and motor fibers from the
bulbar part of the spinal accessory nerve, glossopharyngeal
also for middle constrictor; inferior constrictor has in addition
fibers from the external and inferior laryngeal nerves. Stylo-
pharyngeus is supplied by the glossopharyngeus.

The Muscles of the Soft Palate

The soft palate (velum pendulum palati) is continued back
from the hard palate, pendulous posteriorly, prolonged in the
middle into the wvula, and laterally into the posterior pillars
of the fauces, which run to the side of the pharynx; another
fold in front is the anterior pillar of the fauces, descending
to the tongue; between them is the tonsil, and the constricted
part between the anterior pillars is the zsthmus of the fauces.
There are five pairs of muscles—two superior, one intermediate,
and two inferior.

The palatoglossus (constrictor isthmi faucium) occupies the
anterior pillar of the fauces; at its origin in the anterior surface
of the soft palate it is below all the other palatal muscles,
and continuous with its fellow; inferiorly it enters the side of
the tongue and joins the transverse fibers.

The palatopharyngeus (pharyngostaphylinus) rises by two
layers which embrace the levator palati and azygos uvule;
the superficial (posterior) layer is thin, the deep (anterior)
layer is stronger, meets its fellow, and rises in part from the
hard palate and aponeurosis of the velum; it receives one or
two fibers from the cartilage of the Eustachian tube (salpingo-
pharyngeus). It passes down in the posterior pillar, mingling
with the stylopharyngeus, is inserted into the upper and hinder
borders of the thyroid cartilage and fibrous layer of the pharynx,
passing to or crossing the median line.

The azygos uvule (palatostaphylinus), supposed to be single,
consists of two slips which rise from the soft palate and pos-
terior nasal spine and descend into the uvula, separated above,
united below.

Levator Palati.—Origin, petrous portion .of the temporal
bone in front of the carotid canal, from the lower margin of
the cartilage of the Eustachian tube, passes forward over the
superior constrictor, and is inserted by its forepart into the

ki

THE MUSCLES OF THE PHARYNX 165

aponeurosis of the palate, and posteriorly it meets its fellow
under cover of the azygos uvule.

Circumflex, or Tensor Palati.—Origin, scaphoid fossa at the
root of the internal pterygoid plate, spine of the sphenoid, and
outer side of the Eustachian tube; descends vertically and
internally to the internal pterygoid muscle; its tendon turns
around the hamular process, where there is a bursa, then passes
horizontally to its insertion into the transverse ridge of the
palate bone and aponeurosis of the soft palate.

From before backward in the soft palate are the palato-
glossus, tensor palati, anterior part of the palatopharyngeus,
levator palati, azygos uvule, posterior part of the palato-
pharyngeus, and mucous membrane.

Nerves.—Sources not fully determined; tensor palati through
otic ganglion from the third division of the fifth; levator palati,
azygos uvulz, palatoglossus, and palatopharyngeus probably
by the bulbar portion of the spinal accessory nerve through
the pharyngeal plexus.

Actions.—The constrictors are nearly immovable behind,
and so earry back the anterior wall, the hyoid bone and larynx
being carried up and back by the obliquity of the two lower
constrictors. The upper part of the superior constrictor can-
not act directly upon the food, as it is attached at both ends
to immovable parts. The stylopharyngeus is the chief elevator
of the pharynx and larynx; the palatoglossi depress the soft
palate, elevate the tongue, and shut off the mouth cavity
from the pharynx; the palatopharyngei depress the soft palate,
raise the pharynx, and bring the posterior pillars together;
the azygos uvyule raises and shortens the uvula; the levator
palati raises the palate; the tensor palati tightens and sup-
ports the palate against the pull of other muscles and opens
the Eustachian tube in deglutition. Some hold that the tube
is closed in deglutition by the levator palati pressing its floor
against its upper and outer wall. The first stage of deglutition
is effected by the mylohyoid, styloglossus, and palatoglossus
pressing the tongue against the palate; the hyoid is also raised
by its elevators; the larynx is then carried up beneath the
hyoid by the thyrohyoid and stylopharyngeus, the root of
the tongue is drawn back by the styloglossi and the epiglottis
pressed down; at the same time the soft palate is raised and
fixed by its proper muscles; the posterior pillars and uvula

166 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

shut off the posterior nares, and the food is guided into the
lower pharynx, where it is grasped by the constrictors in suc-
cession and forced into the esophagus.

Il. THE DEEP NECK MUSCLES

These are divided by the transverse process into two groups.
The outer from the processes to the ribs corresponding to the
intercostals, those from the processes to the shoulder blade
corresponding to the serratus magnus; the inner group passes
from one process to another, long or short.

OutTEeR Group (four in number).—1. M. Scalenus Anticus.—
Origin, anterior tubercle of the transverse process of the third,
fourth, fifth, and sixth cervical vertebree; insertion, by a thick
flat tendon into the scalene tubercle of the first rib; the pleura
is attached to the lower part of the inner surface of this muscle.

2. M. Scalenus Medius.—Origin, tendinous above, muscular
below, from posterior tubercle of transverse process of all
the cervical vertebrae (sometimes not of the atlas); insertion,
upper edge and outer surface of the first rib from the tuberosity
to the subclavian groove.

3. M. Scalenus Posticus (smaller than the others).—Origin, by
two or three tendons from the posterior tubercles of the lower
two or three cervical vertebre; insertion, by an aponeurotic
tendon into the second rib external to the serratus posticus
superior.

Some regard the scalenus mass as one muscle with three
insertions.

4. M. Levator Scapule (levator anguli scapule).—Origin,
by distinct slips from the transverse process of the upper
four cervical vertebrae between the attachments of the splenius
and sealeni; insertion, posterior border of the scapula from the
spine to the superior angle.

Vertebral attachments various; a slip to it from the occipital
bone or mastoid process; parts from the vertebree may remain
separate to their insertion. In quadrupeds it unites with the
serratus anticus (magnus), and forms one muscle; may send
a slip to the scaleni, trapezius, serrated muscles, or first and
second ribs.

InNER Group.—Long Muscles.—1. M. longus colli rests on
the front of the vertebral column from the atlas to the third

_——

THE DEEP NECK MUSCLES 167

dorsal vertebra. There are three sets of fibers: (a) Vertical
part, from the bodies of the lower two cervical and upper. two

Fie, 29

The prevertebral muscles.

fe
fi

or three dorsal; on its outer border it receives slips from the
lower three or four cervical transverse processes; inserted into
the bodies of the second, third, and fourth cervical vertebra;

168 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

(b) lower oblique part, from the bodies of the upper two or three
dorsal into the anterior tubercles of the fifth and sixth cervical
transverse processes; (c) wpper oblique part is the musculus
longus atlantis of Henle. Origin, anterior tubercle of the
transverse process of the third, fourth, and fifth cervical verte-
bree; inserted into the vertical portion and lateral and lower
part of the anterior tubercle on the arch of the atlas.

2. M. Longus Atlantis (see preceding muscle).

3. M. Longus Capitis, p. n. (rectus capitis anticus major).—
Origin, anterior tubercle of the transverse process of the third,
fourth, fifth, and sixth cervical vertebrie; insertion, basilar
process of the occipital in front of the foramen magnum; it
may show a tendinous intersection anteriorly; the pharynx is
closely attached to it.

Short Muscles—1. Mm. Intertransversarw Anteriores.—
Anterior intertransverse muscles pass as little fasciculi between
the anterior tubercles of the transverse processes of the cer-
vical vertebree; they are in front of the nerve trunks. The
one for the axis is inserted broadly into its transverse process.
They may be lacking for the two upper vertebree.

M. Rectus Capitis Anticus, p. n. (rectus capitis anticus
minor).—Origin, front of root of the transverse process of the
atlas; insertion, basilar process, between foramen magnum and
rectus major, > inch from its fellow.

Nerves.—Rectus anticus minor by the first cervical nerve;
scaleni and long prevertebral muscles by neighboring nerves;
the levator scapule by the third, fourth, and fifth cervical

- nerves.

Actions.—The scalene muscles are elevators of the ribs,
muscles of inspiration; fixed at the ribs are lateral flexors
of the neck, or both sides together bend it forward; the recti
antici flex the head and throw forward the pharynx; the longus
colli flexes the neck, and its oblique parts may rotate; the
levator scapula elevates the superior angle and base of the
scapula, counteracting the rotation of the trapezius; fixed
below, draws the neck back and to one side.

THE MUSCLES OF THE HEAD

These belong to the skull and face; those of the face are
in three groups and in three layers.

THE EPICRANIAL MUSCLES 169

THE EPICRANIAL MUSCLES

M. Epiecranius, p. n. (occipitofrontalis), comprises the
occipital and frontal muscles on either side, united by the
galea aponeurotica, p. n. (epicranial aponeurosis). This covers
the upper surface of the skull without division, closely attached to
integument and loosely to pericranium. Behind, it is attached
to the occipitales muscles, to the occipital protuberance, and
supreme curved lines; it terminates anteriorly in the frontales;
laterally has no distinct margin, but beneath it a thin fascia
springs from the superior temporal line and passes under
the auricular muscles to the pinna. The frontalis muscle (mus-
culus epicranialis frontalis) rises from the aponeurosis between
the coronal suture and the frontal eminence; inferiorly it ends in
subcutaneous tissue at the root of the nose (pyramidalis nasi
is a part of it, Henle), inner canthus of the eye, and whole
length of the eyebrow, continued into the pyramidalis nasi
and interlacing with the corrugator supercilii and orbicularis;
the margins of the right and left are united near the root of
the nose, but separated higher up.

The occigitalis muscle (musculus epicranialis occipitalis)
is attached to the outer two-thirds of the superior curved line
and to the mastoid process; its fibers, 1 to 2 inches long, ter-
minate in tendon, and that in aponeurosis; an interval between
the muscles is occupied by aponeurosis.

Henle describes the auricular muscles as a part of the epi-
cranius; the musculus epicranialis temporalis is the auricularis
anterior of Quain; rises from the root of the zygoma and bony
external auditory meatus; connected with the helix and cap-
sule of the lower jaw, its fibers pass up and forward to the
edge of the frontalis muscle and orbicularis oculi, and meet
the platysma below.

The musculus (epicranialis) auricularis superior rises from
the galea aponeurotica, and converges to the helix by one
tendon, and by another to an eminence on the inner surface
of the pinna.

The musculus (epicranialis) auricularis peas rises from
the mastoid, sternomastoid aponeurosis, and outer part of
the superior curved line, and is inserted into the vertical ridge

170 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

at the back of the concha. All of the ear muscles are more
or less connected. .

Actions.—The frontales elevate the eyebrows, draw the
scalp forward, and wrinkle the forehead transversely; occipi-
tales draw the scalp back or may alternate with the frontales.
Most persons have only partial control, best in case of frontales.
The actions of the ear muscles are slight or nil; the anterior
makes tense the temporal fascia, and has no effect on the
ear; they may enlarge the entrance to the external ear.

THE MUSCLES OF THE EYELIDS AND EYEBROWS

M. orbicularis oculi, p. n., has three parts, is thin and elliptical,
covers the eyelid, and extends some distance on the forehead,
temple, and cheek.

The pars palpebralis, p. n., is contained in the eyelids, rises
from the upper and lower margins of the internal tarsal liga-
ment, and passes out in a slight curve to the external tarsal
ligament. A thicker fasciculus along the free margin of each
lid is the ciliary bundle.

The pars orbitalis, p. n., is larger and stronger, attached to
the nasal process of the superior maxilla, inner part of the
orbital arch, and externally to the cheek, forming a series of
concentric loops. The musculi malaris of Henle are the lower
converging fibers of the orbital part, passing to the skin of
the cheek and muscles.of the upper lip.

The pars lacrymalis, p. n. (tensor tarsi or Horner’s muscle),
extends from the lacrymal crest behind the sac, and divides into
two slips behind the lacrymal canals for the ciliary bundles
of the orbicularis.

The internal palpebral ligament (tendo oculi) is 2 lines long
and attached to the nasal process of the superior maxilla in
front of the lacrymal groove; thence it passes to the inner
commissure of the eyelids, splitting and terminating on the
tarsi; it crosses the lacrymal sac in front, and gives off a pro-
cess which passes behind the sac to the crest of the lacrymal
bone.

The external palpebral ligament is weaker, and attaches the
lid to the malar bone.

The corrugator supercilit (described by Henle as a part of

THE MUSCLES OF THE ORBIT 171

the orbicularis) rises from the glabella, and passes up and
out to end at the middle of the orbital arch in the orbicularis
and skin of the eyebrow.

The levator palpebre superior will be described with the
orbital muscles.

Actions.—Palpebral part closes the lids; upper half of the
orbital part depresses the eyebrow and opposes the frontalis,
used in forcible closure of the lids; in common winking the
palpebral part carries forward the internal palpebral ligament
and anterior wall of the lacrymal sac, and sucks in tears; the
pars lacrymalis (tensor tarsi) probably alternates with the
palpebral part, draws back the palpebral ligament, and com-
presses the sac. ‘The corrugator produces vertical wrinkles at
the inner end of the eyebrow.

THE MUSCLES OF THE FACE

Only one of these, the buccinator, will be described. All
the others are unimportant.

M. buccinator (trumpet muscle), a flat layer forming 4 large
part of the wall of the mouth; attached at the upper and lower
margins to the alveoli of the maxillary bones opposite the
molar teeth, posteriorly to the pterygomaxillary ligament,
separating it from the superior constrictor of the pharynx,
fibers become thickened at the angle of the mouth and join
the orbicularis; higher and lower fibers are directed to corre-
sponding lips, middle ones decussate, the upper to the lower
lip, the lower to the upper lip.

Nerve supply is from the facial.

Action is to flatten the cheek, keep food between the teeth,
and to expel air from the mouth.

THE MUSCLES OF THE ORBIT

There are seven for description. The M. levator palpebre
superiors (origin, above the optic foramen and superior rectus)
ends in a membranous expansion; inserted into the fibrous
tarsus of the upper eyelid.

The four straight muscles have a continuous tendinous origin

172 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

at the apex of the orbit from a ligamentous ring which encircles
the optic foramen and crosses the sphenoidal fissure; most
of the fibers spring from two common tendons; the upper one
rises from the inferior root of the small wing of the sphenoid,
and is prolonged into the internal, superior, and external
recti; the lower (Zinn) rises from the body of the sphenoid
and divides into three slips for the internal, inferior, and external
recti. All the recti are inserted into the sclerotic 3 or 4 lines
from the cornea; the external has two heads, between which
pass the third, nasal branch of the fifth, the sixth nerve, and
ophthalmic vein. The external and inferior recti are the longest,
internal broadest, and superior smallest.

The superior oblique, or trochlearis, is internal to the levator
palpebre, rises just in front of the optic foramen, and passes
forward to a round tendon which plays through a fibrocartilagi-
nous ring attached to the trochlear fossa of the frontal; it is
there bent out, back, and down between the superior rectus
and eye, and is inserted beneath the outer edge of the superior
rectus midway between the cornea and optic nerve. The
pulley is lined with a synovial sheath.

The inferior oblique rises from the orbital plate of the superior
maxilla close outside the orifice of the nasal duct; the muscle
passes out, back, and up between the inferior rectus and floor
of the orbit, and is inserted under cover of the external rectus
at the back part of the eyeball, nearer the optic nerve than
at the cornea.

Nerves.—External rectus by the sixth nerve, superior oblique
by the fourth, and the other five by the third nerve.

Actions.—Levator palpebre is the elevator of the upper
lid and antagonist of the palpebral part of the orbicularis.
The eyeball seems to move on a central fixed point without
shifting its place as a whole within the orbit; four movements
are possible: (1) Lateral; (2) elevation and depression; (3)
oblique niovements of elevation and depression; (4) rotation
about a sagittal axis. The eaternal and internal recti produce
only lateral movements; the swperior and inferior rectt have
their line of direction internal to the centre of motion, and
so produce not only elevation and depression, but also inward
direction and slight rotation; this is corrected by the oblique
muscles, the inferior oblique being associated with the superior
rectus, and superior oblique with the inferior rectus; the superior

THE MUSCLES OF MASTICATION 173

oblique turns the cornea down and out, the inferior up and
out.

Around the orbit are soft fat and the capsule of Ténon, form-
ing a socket attached in front to the ocular conjunctiva; a

Fia. 30

ee = :

Wy \\ x (A =

z\

Muscles of the right orbit.

large lymph space is between it and the eye; it is pierced by
the eye muscles and sends a tubular prolongation upon each.
The suspensory ligament of the eye is a thickening of the lower
part of the capsule, attached at each end to the orbital margins
and supporting the eye in its socket.

, THE MUSCLES OF MASTICATION

There are four pairs, two outside and two inside the jaw
bone. The masseteric fascia is a part of the deep cervical,
covers the masseter muscle, invests the parotid gland (parotid
fascia), and forms the stylomaxillary ligament.

1. M. masseter, a quadrate muscle with two parts; the super-
ficial part is the larger and rises by an aponeurosis from the

174 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM —

malar process of the superior maxilla, and lower border of the
zygomatic arch for its anterior two-thirds by tendinous bundles
which project between the muscular fasciculi; it passes down
and back to the lower half of the jaw from the angle to the
third molar tooth; the deep part is triangular, and passes yearly
vertically from the posterior third of the zygoma, lower border,
and from all the deep surface of the arch; inserted, after unit-
ing with the superficial part, into the upper half of the ramus
and coronoid; this is almost wholly covered by the superficial
portion.

There may be a bursa between these two parts.

The buccal fat pad is between the forepart of the masseter
and the buccinator, and is prolonged into the zygomatic fossa;
it is well developed in the infant, and inappropriately called
the “sucking pad.”

The temporal fascia is a dense aponeurosis covering the
temporal muscle above the zygoma; it is attached to the tem-
poral crest of the frontal and upper temporal line, and below
divides into two layers attached to the inner and outer sur-
faces of the zygomatic arch; it is separated from integument
by a lateral projection of the galea aponeurotica, and by the
superior and anterior auricular muscles.

2. M. temporalis rises, fan-shaped, from the whole of the
temporal fossa (not its anterior malar wall), which is covered
with fat, from the deep surface of the temporal fascia, and
may blend with some deep fibers of the masseter. The anterior
fibers are nearly vertical, the posterior nearly horizontal;
all converge to a tendon which is inserted into the posterior
and anterior borders of the coronoid process, and deeper fibers
have a fleshy insertion into its inner surface as far as the union
of the ramus and body of the jaw.

3. M. pterygeideus externus occupies the zygomatic fossa,
and rises by two heads, the upper and smaller from the zygo-
matic surface of the great wing of the sphenoid and infra-
temporal crest or pterygoid ridge; the lower and larger from
the outer surface of the external pterygoid plate. The fibers
from both pass back, converging to a fossa on the front of the
neck of the lower jaw, to the interarticular cartilage and capsule.
A venous plexus is between its upper surface and base of the
skull.

THE MUSCLES OF THE NECK AND BACK 175

4. M. pterygoideus internus arises also by two heads—one
from the pterygoid fossa, the greater portion from the inner
surface of the external plate, from the tuberosity of the palate
bone between the two plates; a second small slip outside of
the external pterygoid muscle from the tuberosities of the
palate and superior maxilla; the fibers pass downward, back-
ward, and outward to be inserted into the inner surface of
the ramus of the mandible, between its angle and dental fora-
- men; it is disposed in a way corresponding to the insertion
of the masseter on the outer surface of the mandible near
the angle.

Nerves.—All from the inferior maxillary division of the
fifth cranial.

Actions.—Masseter, temporal, and internal pterygoid elevate
the lower jaw; the external pterygoid protrudes the lower
jaw, or alternately produces a grinding of the molar teeth;
it may also assist in opening the mouth when the condyles
are carried forward upon the articular eminences. The back
part of the temporal and the deep part of the masseter retract
the jaw.

THE MUSCLES AND FASCLZ OF THE TRUNK

THE MUSCLES OF THE NECK AND BACK

The fascia covering the first layer of muscles is divided into
a superficial and deep layer.

The superficial fascia is found beneath the skin. Contains
considerable adipose tissue and is continuous with the super-
ficial fascia covering the rest of the body.

The deep fascia is a thick fibrous layer, which covers over
and forms sheaths for the muscles. It is attached to the oc-
cipital bone, the crest of the ilium, the spines of the vertebre,
and the spine of the scapula. In the neck it forms the posterior
portion of the deep cervical fascia; in the thorax it blends
with the axillary fascia and deep fascia of the thorax; it is
continuous with abdominal fascia surrounding the muscles;
forms the dorsal layer of the lumbar fascia, and covers the
erector spins mass of muscles. In the back of the thorax it
is called the vertebral aponeurosis.

176 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

First Layer.—1. Trapezius (cucullaris), or hood muscle.—Origin,
inner third superior curved line of occipital bone, ligamentum
nuchee, spinous processes of the seventh cervical, and of all
the dorsal vertebree and supraspinous ligament; insertion,
fibers converge to shoulder girdle; superior ones to outer third
or half of posterior border of clavicle; middle fibers horizontally
to inner margin of acromion and superior lip of scapular spine;
inferior fibers up and out to a triangular tendon gliding over
the inner extremity of the spine of the scapula and inserted
into a tubercle on its upper lip. The aponeuroses of the two
muscles form an ellipse widest at the seventh cervical spine.

2. M. Latissimus Dorsi, broad and flat at its origin, narrow
at its insertion.—Origin, spinous processes of the lower six or
seven dorsal vertebre, posterior layer of the lumbar aponeu-
rosis which attaches it to the lumbar and sacral spines and
iliac crest, from the external lip of the iliac crest in front of
the lumbar aponeurosis; from the last three or four ribs by
digitations interposed between those of the external oblique;
often by a slip from the inferior angle of the scapula. Its
upper fibers are nearly horizontal, middle oblique, and the
lower vertical; it winds around the teres major and in front
of it, and is inserted by a tendon 1% inches wide into the floor
of the bicipital groove, a little higher than the teres major,
and by its upper edge into the inner lip of the groove limiting
the insertion of the subscapularis.

Second Layer.—1. M. Rhomboideus Minor. —Origin, seventh
cervical and first dorsal spines and ligamentum nuche of
that region; insertion, vertebral margin of scapula opposite
triangular surface at commencement of the spine.

2. M. Rhomboideus Major.—Origin, spinous processes of
four or five upper dorsal vertebrze and supraspinous ligament;
insertion, vertebral margin of scapula between the spine and
the inferior angle. The greater part of its fibers are not fixed
directly to bone, but.end in a tendon attached to the lower
angle of the scapula, so that the muscle acts more especially
upon this angle.

3. Levator Angulis Seapult.—Origin, by tendinous slips
from the transverse process of the atlas, the posterior tubercles
of the transverse processes of the second, third, and fourth
cervical vertebre; insertion into the posterior border of the

THE MUSCLES OF THE NECK AND BACK 177

scapula, between the superior angle and the triangular smooth
surface at the root of the spine.

Fig. 31

o

p

Mh,

ba

afi

Cc
ta|

Muscles in the second layer of the back and on the dorsum of the shoulder. (Testut.)
12

178 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

Third Layer.—Serratt Muscles—1. M. Serratus Posticus
Supervor.—Origin, by a thin aponeurosis from two, rarely
three, upper dorsal spines, supraspinous ligament, ‘seventh
cervical spine, lower part of ligamentum nuchee; fibers pass
down and out; inserted by four slips into the upper border
and outer surfaces of the second, third, fourth, and fifth ribs
cp bdae: their angles.

M. Serratus Posticus Inferior (broader than the above).—
peli by part of the lumbodorsal aponeurosis from first two
lumbar and last two or three dorsal spines; passing up and
out; inserted by four slips into the lower borders of the last
four ribs up to the origin of the latissimus dorsi.

3. Mm. Splenii.—Named from strap-like action binding
down underlying parts; rise from lower half of neck and upper
half of back.

(a) M. Splenius Capitis. —Origin, ligamentum nuche over
third, fourth, fifth, and sixth cervical spines, from seventh
cervical and first two dorsal spines; insertion, outer surface
and posterior margin of mastoid process, outer part of superior
curved line to insertion of trapezius.

(b) M. Splenius Cerrmers (colli) —Origin, below the above
from the third, fourth, fifth dorsal spines, not lower than the
sixth; insertion, with slips of the levator anguli scapule into
the tips of the transverse process of the first and second, often
third, cervical vertebre.

The splenii are covered in part by the trapezius, rhomboidei,
and superior serratus; the complexus comes to view internal
to them.

Nerves.—Trapezius by the spinal accessory, third, and fourth
cervical nerves; rhomboidei by the fifth cervical nerve; teres
major by the lower subscapular nerve (sixth and seventh
cervical); latissimus dorsi by the long subscapular nerve
(seventh and eighth cervical); the serrati by the intercostals
or the upper slip of the serratus posticus superior by the cervical
plexus; the splenii by the posterior spinal nerve.

Actions.—7'rapezius, upper part supports shoulder, raises
point of the shoulder by rotation of the scapula, acts in forced
respiration; middle part adducts the scapule, helps elevate
the shoulder, throws the chest out; inferior part would alone
depress and carry the scapule in, but in concert with the
upper two-thirds of the muscle it raises the acromion and

Wit wee ee Try OE

THE MUSCLES OF THE NECK AND BACK 179

carries the lower angle out and up. Fixed below, one acting,
draws the head back and rotates the face to the opposite side;
both acting, draw the head back. The rhomboidei are special
antagonists of the serratus magnus; they elevate the superior
angle of the scapula and counteract the rotation of the trape-
zius; combined with the trapezius, the scapula is raised without
rotation or drawn back and in. Levator anguli scapuli raises
the angle of scapula, and assists the trapezius in bearing weights
and shrugging the shoulders. If the shoulder be fixed the
levator anguli inclines the head to the same side, also rotating
it in a similiar direction. Latissimus dorsi, fixed at humerus,
draws the body forward as in using crutches or climbing,
feebly in forced respiration; fixed below, carries the elevated
arm down, back, and rotates in; draws the shoulder down and
back, is used in swimming; keeps the inferior angle of scapula
close to the chest wall.

Serratus posticus superior, muscle of forced inspiration;
serratus posticus inferior, muscle of forced expiration (Quain
says of inspiration, as it holds the lower ribs fixed when the
diaphragm tends to draw them up).

Spleni of one side draw the head and neck back and rotate
the face to the same side; help keep the head erect.

The vertebral aponeurosis consists of longitudinal and trans-
verse fibers; above, it passes beneath the serratus posticus

’ superior and splenius muscles, to blend with the deep cervical

fascia; below, it is continuous with the intercostal fascia;
internally attached to the spinous processes of the thoracic
vertebree; externally, to the angle of the ribs.

The lumbar fascia is the same as the posterior aponeurosis
covering the transversalis abdominis muscle and is divided into
three layers: The dorsal layer is attached to the spines of the
lumbar and sacral vertebree, and their supraspinous ligaments;
the middle layer to the tips of the transverse processes, and
intertransverse ligaments of the lumbar vertebrae; the ventral
layer, to the roots of the transverse processes of the lumbar
vertebre.

Fourth Layer.—M. Sacrospinalis, p. n.' (erector spinz).—
Origin, lowest two or three dorsal, all the lumbar and sacral

1A commission of anatomical nomenclature has suggested for universal use names
here marked p. n. (proposed name). It is practically the nomenclature of Henle.

180 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

spines, posterior fifth of inner lip of the iliac crest, lower and
back part of the sacrum, anterior surface of the lumbar fascia;
opposite the last rib this mass divides into the middle and
outer columns, and an inner one, spinalis dorsi, separates
from the middle in the upper dorsal region. The outer and
middle portions subdivide.

I
(a) Middle column. (b) Outer column.
Longissimus dorsi (Longissi- Sacrolumbalis (Iliocostalis
mus dorsi, p. 7.). lumborum, p. 7.).
Transversalis cervicis (Longis- Musculus Accessorius (llio-
simus cervicis, p. 7.). costalis dorsi, p. n.).
Trachelomastoid (Longissimus Cervicalis ascendens (Ilio-
capitis, p. n.). costalis cervicis, p. n.).
(c) Inner column. :
Spinalis dorsi. Spinalis colli or cervicis.
II
Complexus.

M. iliocostalis lwumborum (sacrolumbalis) from the outer

and superficial portion of the common mass into the angles —

of the lower six or seven ribs.

M. ilhocostalis dorsi (accessorius), from ribs into which the
preceding is inserted, but internal to it, into the angles of the
upper six ribs and transverse process of the seventh cervical
vertebra.

M. iliocostalis cervicis (cervicalis ascendens) continues the
series from the angles of the upper four or five ribs into the
posterior tubercles of the fourth, fifth, and sixth cervical trans-
verse processes.

M. longissimus dorsi rises from the common mass, has two
sets of insertions—the inner row of round tendons into all the
dorsal transverse processes and lumbar accessory processes; an
outer row to the lowest nine ‘or ten ribs between the angles and
tuberosities, and to the whole length of the lumbar transverse
processes and into the lumbar fascia.

M. longissimus cervicis (transversalis cervicis), from the
highest four or five dorsal transverse processes into posterior

THE MUSCLES OF THE NECK AND BACK 181

tubercles of the transverse processes of the five cervical vertebrie,
second to sixth inclusive.

M. longissimus capitis (trachelomastoid), by four tendons
from the upper dorsal transverse process, and from the articular
process of the lower three or four cervical vertebre, into the
posterior margin of the mastoid process under the splenius
capitis and sternomastoid. It shows a tendinous intersection
near its insertion; it is the only muscle between the splenius
and complexus. |

Muscula spinales, spinous muscles, have an arched direction.
1. M. spinalis dorsi, close inside the longissimus dorsi and
connected with it; origin, lowest two or three dorsal spines
and from tendons passing from the upper lumbar spines to
the longissimus dorsi; inserted by four to nine slips into the
upper dorsal spines.

2. M. spinalis cervicis, inconstant or different on the two
sides from the ligamentum nuche and _ seventh cervical
spine, and one or two above or below this; inserted into
the spine of the axis or also into the third and fourth cervi-
cal spines.

Complexus Muscle.—Origin, from the tips of the transverse
processes of the upper six or seven thoracic and the last cervical
vertebrze, and from the articular processes of the fifth, sixth,
and seventh cervical vertebrae; forming a broad muscle, which
is inserted into the innermost depression between the two
curved lines of the occipital bone.

Fifth Layer.—(a) Mm. Semispinalis (half-spinous).—(1) M.
semispinalis dorsi, by five or six tendons from the trans-
verse process of the dorsal vertebra, from the sixth to the
tenth inclusive; inserted by just as many tendons into the
spines of the upper four dorsal and lower two cervical vertebra.
(2) M. semispinalis cervicis, covered by the complexus, rises
nearly from the insertion vertebrae of the preceding, viz.,
upper five or six dorsal transverse processes; inserted into the
cervical spines from the second to the fifth, inclusive, being
thickest into the axis. (3) M. semispinalis capitis (complexus)
rises by two sets of heads; the inner, or biventer cervicis, rises
from three or four dorsal transverse, processes between the
second and sixth; its superficial fibers are inserted into the
external occipital protuberance beside the ligamentum nuche;
its deeper fibers join the external head. The outer head rises

182 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

from the upper dorsal and Jower three or four cervical verte-
bree, on the dorsal and seventh cervical from the transverse
process, on the remaining cervical vertebree (fourth, fifth, or
sixth) by two slips from each, one from the posterior tubercle
of the transverse process, and one from the lower articular
process. These fibers unite, join part of the inner head, and
are inserted into the inner impression between the two curved ~
occipital lines. A tendinous inscription crosses the muscle
near the spine of the axis; another crosses the biventer lower
down.

(b) M. multifidus spine occupies the groove beside the spinous
processes from the sacrum to the axis; rises from the deep
surface of the erector spine, from the back of the sacrum as
low as the fourth foramen, posterior extremity of the ilium,
and posterior sacroiliac ligament; in the lumbar region from
the mammillary processes; in the dorsal, from the transverse
process; in the cervical, from the articular processes of the four
lower vertebree. The bundles pass up and in, to be inserted
into the whole length of the spines from the last lumbar to
the axis; some fibers go to the fourth vertebra above, others
to those nearer.

(c) Mm Rotatores—1. Mm. rotatores longi, really a part
of the multifidus, only in the dorsal region, from the upper
edge of a transverse process into the lateral edge of the root
of the second or third spinous process above.

2. Mm. rotatores breves (rotatores dorsi of Quain), eleven
in number, dorsal region, nearly horizontal, from the upper
edge of a transverse process into the lower edge of the lamina
above.

Of Flexion Vertebre.—Mm. interspinales, vertical sets of
fibers in pairs between contiguous spinous processes; in the neck
they are round, in the back are usually absent, in the loins are
flat from side to side.

Mm. Intertransversales (posteriores, as there is also an anterior
set in the neck).—In the lumbar region there are two parts—
an inner, ¢ntertransversalis posticus medialis, from a mammillary
process into an accessory or mammillary process next above;
an external, intertransversalis posticus lateralis, between two —
contiguous transverse processes. In the back the inner por-
tion is supplied by the intertransverse ligaments, the outer
portion by the levator costarum; in the neck and upper dorsal

THE MUSCLES OF THE NECK AND BACK 188

region they are single bands between the transverse process
and behind the cervical nerves.

Short Muscles of Rotation Vertebre and Occiput.—Five on
each side; two rise from the axis and three from the atlas.
(1) M. rectus capitis posticus major.—Origin, spine of the axis,
upper border; insertion, into and below the middle third of the
inferior curved line of the occiput. (2) M. obliquus capitis
inferior, strongest of these muscles.—Origin, upper and pos-
terior part of the arch of the axis (Henle); insertion, back part
of the transverse process of the atlas. (3) M. rectus capitis
posticus minor.—Origin, posterior tubercle of the atlas; insertion,
into and beneath the inner third of the inferior curved line
of the occiput, covered partly by the major muscle. (4) M.
obliquus capitis superior —Origin, upper surface of transverse
process of the atlas; insertion, impression between the outer
parts of the occipital curved lines. (5) M. rectus capitis lateralis.
—Origin, anterior surface of the apex of the transverse proces
of the atlas; passes nearly straight up to the jugular process
of the occiput.

The two oblique muscles, with the rectus capitis posticus
major, form the suboccipital triangle, in which are found the
vertebral artery and the posterior primary branch of the sub-
occipital nerve (Quain).

The extensor coccygeus is a slender fasciculus, occasionally
present, which extends over the lower part of the posterior
surface of the sacrum and coccyx. It arises by tendinous
fibers from the last bone of the sacrum or first piece of the
coccyx, and passes downward to be inserted into the lower
part of the coccyx. It is a rudiment of the extensor muscle
of the caudal vertebrae of the lower animals (Gray.)

Nerves.—All of the foregoing muscles of the neck and back
are supplied by posterior primary branches of the spinal nerve.

Actions.—The longitudinal muscles extend the back with
a force of 200 to 400 pounds; some of the lower muscles may
depress the ribs and aid in forced expiration; some of the upper,
if fixed above, may act in forced inspiration. The muscles
of one side produce lateral flexion of the spinal column. The
complexus and transversospinalis rotate the head and spine
to the opposite side. The rectus minor and superior oblique
chiefly extend the head; the rectus major and inferior oblique
rotate the atlas and skull on the axis; the major also extends

184 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

the head. The levatores costarum have but little action on the
ribs; are regarded as muscles of forced inspiration. The rectus
lateralis bends the head to one side.

THE FASCIZ AND MUSCLES OF THE ABDOMEN

The fascia of the abdomen is divided into a superficial, and
a deep aponeurosis. ‘The superficial fascia is subdivided into a
superficial layer and a deep layer.

The superficial layer of the superficial fascia (Camper’s
fascia) is continuous with the fascia over the thorax, back,
and thighs, and in the male it passes over the penis and outer
surface of the cord to the scrotum, helping to form the dartos;
from here it is traced backward as the superficial layer of the
superficial fascia of the perineum;.in the female it passes to the
labia majora. The deep layer of the superficial fascia (Scarpa’s
fascia) is continued above with the superficial layer of the
superficial fascia; it is adherent internally to the linea alba and
symphysis pubis; below it forms the suspensory ligament of the
penis and laterally passes over Poupart’s ligament to blend with
the fascia lata of the thigh; at the root of the penis it passes
over the latter organ and the scrotum and cord to help form
the dartos. At the margin of the dartos it is continuous
with the deep layer of the superficial fascia of the perineum
(Colles’ fascia); in the female it is continuous with the labia
majora.

The deep abdominal fascia covers the aponeurosis of the
external oblique muscle, but is so closely adherent that it is
difficult of demonstration.

1. M. rectus abdominis, separated from its fellow by the
linea alba.—Origin, cartilage of the fifth, sixth, and seventh
ribs, and usually bone of the fifth, by three slips, sometimes
from the ensiform; insertion, by two tendons, the inner smaller
one into the front of the symphysis pubis, crossing its fellow
of the opposite side, passing down and out to the adductor
fascia, down and in to the fascia of the penis; the outer head
into the pubic crest or space in front of it if the pyramidalis
is lacking. (Henle considers the insertion as below, as it passes
into so much movable fascia.) The fibers are interrupted
by zigzag transverse tendinous intersections, linea transverse.

THE FASCIA AND MUSCLES OF THE ABDOMEN 185

2. M. pyramidalis rests on the lower part of the rectus inside

its sheath, separated from it by a special fascia. Origin, front
of the pubis below the insertion of the outer tendon of the
rectus, passes over the lower third of the space between the
umbilicus and pubis; inserted into the linea alba. Its inner
fibers are vertical, outer ones oblique.

The linea alba is a fibrous structure from the ensiform to
the pubis, formed by the union of the oblique and transverse
aponeuroses, broadest above, + inch (4 to 7 mm.), and a little
below its middle is the cicatrix of the wmbilicus. At the lower
end it passes in front of the recti, and here is detached pos-
teriorly a band of longitudinal fibers = adiminiculum linee
albe, spreading out triangularly behind the outer heads of
the recti.

The linea semilunaris is a depression seen on the outer side
of each rectus abdominis muscle, and corresponds to the line
of fusion of the aponeuroses of the oblique and transversalis
muscles, as they blend to pass in front and behind the recti
muscles to form the sheath of the latter muscles. It extends
from opposite the ninth costal cartilage to the spine of the
pubic bone.

Linez transverse are depressions seen along the recti muscles,
and correspond to the attachment of the aponeuroses of the
abdominal muscles to the rectus. They are usually three—
one below the ensiform cartilage, one between the ensiform and
the umbilicus, and one opposite or below the umbilicus.

1. M. obliquus externus, or descending oblique, is muscular
on the side, aponeurotic in front.—Origin, outer surfaces and
lower borders of the lower eight ribs (seven, Henle) by slips
in a serrated series, five interdigitating with the serratus mag-
nus, the lower three with the latissimus dorsi, from the lumbo-
dorsal aponeurosis connected with first lumbar vertebree. ‘The
slip from the eighth rib is broadest, the others diminish above
and below that; upper and lower digitations rise from near
the costal cartilages, the intermediate ones at some distance
from them. |

The fibers from the last two ribs pass nearly vertically down
to insert the anterior half of the outer lip of the iliac crest;
all the rest incline down and forward to the aponeurosis. This
is wider below than above, meets its fellow in the linea alba,
is connected with the costoxiphoid ligament, gives origin to

186 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

the lowest fibers of the pectoralis major, or is covered by a
fascia derived from it; below it extends from the anterior
superior spine of the ilium to the spine of the pubis as a
thickened border called Poupart’s ligament. Poupart’s ligament
affords attachment throughout its entire length to the
aponeurosis of the external oblique muscle; its outer half
gives attachment to the internal oblique and transversalis |
muscles. |

The aponeurosis is perforated by a large opening near the
pubis for the spermatic cord in the male and round ligament
in the female; this is the external abdominal ring (annulus
inguinalis cutaneus, p. n.). It is oval or elliptical, 1 inch long,
> inch wide in the male, with its base at the pubic crest; its
sides are the pillars (crus superius and crus inferius, p. 7.);
the wpper or inner is flat and straight, attached to the anterior
surface of the pubis, decussating with its fellow or passing to
the adductor fascia and dorsum of the penis; the lower or
external is thin above, and below is formed by the inner end
of Poupart’s ligament, attached to the spine of the pubis.
The intercolumnar fibers are seen passing across the two pillars
of the external abdominal ring, and gives off a thin aponeurosis,
which passes on to the spermatic cord, called the intercolumnar
fascia.

The deepest fibers of Poupart’s ligament are sent back to
the inner part of the iliopectineal line for 2 inch, forming a
layer called Gimbernat’s ligament, presenting upper and lower
surfaces and a concave margin toward the femoral ring and
vein. Some of the fibers of Gimbernat’s ligament or of the
outer pillar are reflected up and in, under the spermatic cord,
behind the inner pillar, in front of the conjoined tendon, cover-
ing the posterior wall of the external ring, and pass to the
sheath of the linea alba or interlace with the opposite external
oblique muscle; this is the reflected Gimbernat’s ligament, or
triangular fascia.

Cooper’s ligament, described first by Sir Astley Cooper.
It extends from the base of Gimbernat’s ligament along the
iliopectineal line, to which it is attached. It is strengthened
by the fascia transversalis, the iliopectineal aponeurosis, and
by a lateral expansion from the lower attachment of the linea
alba (adminiculum lines albze) (Gray).

Generally the external oblique and latissimus dorsi leave

THE FASCIZ AND MUSCLES OF THE ABDOMEN 187

a triangular space between them on the iliac crest, forming
Petit’s triangle. ‘Thirty or forty cases of lumbar hernia pro-
truding through this space have been recorded.

2. M. Obliquus Internus.—Origin, outer half of Poupart’s
ligament, anterior two-thirds of the middle ridge of the iliac
crest, from the lumbar fascia; insertion, lower margins of the
cartilages of the last three ribs, its aponeurosis, and by con-
joined tendon (with transversalis) arching over the inguinal
canal to the front of the pubis and inner part of the iliopec-
tineal line behind Gimbernat’s ligament. Sometimes the con-
joined tendon divides into an outer portion, the ligament of
Hesselbach; and an internal portion, the ligament of Henle. The
aponeurosis splits at the outer border of the rectus; the anterior
layer unites with the external oblique aponeurosis, the posterior
‘ with the transversalis aponeurosis, which reunite and form
the sheath of the rectus; the posterior layer is attached above
to the ensiform, seventh and eighth rib cartilages. This divi-
sion of aponeurosis stops a little above half-way between the
umbilicus and pubis, and below this point the internal oblique
aponeurosis and transversalis aponeurosis pass wholly in front
of the rectus. This deficiency in the posterior wall of the
sheath is marked by a lunated edge, concave downward, the
semulunar fold of Douglas (linea Douglasii, p. n.); here the
rectus is separated from the abdominal contents by perito-
neum, subperitoneal tissue, transversalis fascia, and a thin
connective tissue which continues the transverse aponeurosis.
(Note a difference between the transversalis fascia and the
aponeurosis. )

The cremaster muscle, peculiar ‘is the male, is attached
externally to the inner portion of Poupart’s ligament, and is
continuous with the internal oblique fibers; its internal attach-
ment (inconstant) is the spine and crest of the pubis; it descends
in folds in front of the spermatic cord to the level of the testis,
and spreads out in a cremasteric fascia. Some regard this
muscle as a part of a fetal structure called gubernaculum testis.
There are some remains of it in the female.

3. M. Transversalis Abdominis.—Origin, inner surface of
the lower six rib cartilages, interdigitating with the diaphragm,
from the lumbar transverse process by a posterior aponeurosis,
from the anterior three-fourths of the inner margin of the
iliac crest, outer third of Poupart’s ligament. This muscle

188 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

nearly surrounds the abdomen, and is inserted into the anterior
aponeurosis and conjoined tendon. This aponeurosis com-
mences for the most part about 1 inch from the outer border
of the rectus in the linea Spigelii (p. n.), but muscular fibers
nearly meet behind the rectus above; the lower third of this
aponeurosis passes in front of the rectus.

The posterior aponeurosis is the middle layer of the lumbar
fascia or lumbocostal ligament (Henle), between the erector
spine and quadratus lumborum muscles. The highest part
of this muscle is continuous with the triangularis sterni.

Nerves.—Supplied in general by the lower intercostal nerve;
internal oblique and transversalis, also by the iliohypogastric
and the ilioinguinal nerves; the cremaster by the genital branch
of the genitocrural nerve. :

Actions.—Upon the thorax, viscera, or vertebral column;
pelvis and thorax fixed, they aid vomiting, expulsion of fetus,
feces, and urine; vertebral column fixed, they raise the dia-
phragm by pressing up the viscera, and so aid expiration; flex
the thorax to the front or laterally, or rotate it if the vertebral
column be not fixed; thorax fixed, draw up the pelvis in climb-
ing. Pyramidales make the linea alba tense.

THE LINING FASCLZ OF THE ABDOMEN

The transversalis fascia covers the inner surface of that
muscle, and is continued upon the under surface of the dia-
phragm; along the inner margin of the iliac crest it is attached
to the periosteum; for about 2 inches internal to the anterior
superior iliac spine it is attached to the back of Poupart’s
ligament and the iliac fascia; next internally it passes down
over the femoral vessels as the anterior portion of their sheath;

as it passes under Poupart’s ligament it is strengthened by —

the deep crural arch (arcus cruralis), a band of fibers inserted
into the pubic spine and iliopectineal line behind the con-
joined tendon; it includes beneath it, between. the femoral
vein and Gimbernat’s ligament, the femoral ring, through
which a femoral hernia may descend.

The internal abdominal ring is situated in the transversalis
fascia, midway between the spine of the ilium and the crest
of the pubic bone. It is $ inch above Poupart’s ligament,

and is the internal opening of the inguinal canal. It trans-

THE FASCIZ OF THE PERINEUM 189

mits the spermatic cord in the male, and the round ligament
in the female. From its circumference a thin, funnel-shaped
membrane is given off, to continue on to the cord and testes,
as a distinct covering. It is called the infundibuliform or
internal spermatic fascia. The ring is bounded above and
externally by the arched fibers of the transversalis muscle,
below and internally by the deep epigastric vessels and
Hesselbach’s ligament. In front by the internal oblique muscle.

The inguinal or spermatic canal contains the spermatic
cord in the male, and the round ligament in the female. It
is 1} inches in length, parallel to and 4} inch above Poupart’s
ligament. It is bounded in front by the aponeurosis of the
external oblique muscle, throughout its whole length, and by
the internal oblique muscle over its outer third; behind, from
within outward, are the triangular fascia (when present),
the transversalis fascia and conjoined tendon; above by the
arched fibers of the internal oblique muscle; below by Gimber-
nat’s ligament near the external ring, and Poupart’s ligament.
The deep epigastric vessels and Hesselbach’s ligament lie -
behind the middle of the canal.

Hesselbach’s triangle is the interval within the transversalis
fascia, bounded internally by the outer border of the rectus
muscle, externally by deep epigastric artery, and the base is the
inner third of Poupart’s ligament.

The iliac fascia covers the iliopsoas muscle, stretched from
the iliac crest to the iliac portion of the iliopectineal line; it is
continued up on the psoas, attached to the sacrum, inverte-
bral disks, internal arched ligament of the diaphragm, and
externally to the iliolumbar ligament (anterior layer of the
lumbar fascia). Below it passes beneath the femoral vessels,
forming the hinder part of the femoral sheath; outside the
vessels it unites with the transversalis fascia on Poupart’s
ligament and with the external inguinal ligament, which pro-
longs it to the fascia lata (iliac portion); internally it joins the
pubic portion of the fascia lata. A strong band is attached
to the iliopectineal eminence between the psoas and pectineus,
called the zliopectineal ligament.

THE FASCIA OF THE PERINEUM

Superficial.—tIn the anterior half of the perineum, continuous
with the dartos, is the superficial perineal fascia, or fascia of

190 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

Colles, bound to the ischiopubic rami as far back as the ischial
tuberosities; on a line from this tuberosity to the central point
of the perineum it turns around the transversus perinei muscle
and becomes deep perineal fascia. There is an incomplete
median septum, so that extravasated urine distends one side
of the scrotum beneath the dartos, then penetrates to the other
side, then to the front of the abdomen beneath the superficial
fascia, but does not pass to the posterior half of the perineum
nor down upon the thighs. Buck’s fascia is the continuation
forward of Colles’ fascia, investing the penis as far as the
glans, continuous with the dartos, and directing the urine as
already stated.

The deep perineal or subpubic fascia or triangular ligament
of the urethra is stretched across the subpubie arch on the
deep surface of the crura and bulb, and consists of two layers;
the inferior layer extends back to the central point of the
perineum, attached to the ischiopubic rami, connected at its
base with the other layer, and continuous with the recurved
margin of the superficial perineal fascia. This layer, meeting
from below the arcuate pubic ligament (subpubic), forms an
aperture for the dorsal vein of the penis. It is perforated by
the urethra, arteries of the bulb and of the corpora cavernosa,
and ducts of Cowper’s glands.

The swperior (deep) layer consists of right and left lateral
halves, separated in the middle line by the urethra close to the
prostate, and continuous on each side with the fascia covering
the obturator internus muscle. The levator ani is between
this layer and the rectovesical fascia.

Between the two layers of the triangular ligament are the
membranous portion of the urethra, the compressor urethree
muscle, Cowper’s glands, pudic vessels, and dorsal nerves
of the penis.

THE FASCIZ OF THE PELVIS

This consists of two parts, obturator and rectovesical fascia.
The obturator fascia covers the inner surface of thé obturator
internus muscle; it is attached to the iliac portion of the ilio-
pectineal line, to the body of the pubis, to the great sacrosciatic
notch and great sacrosciatic ligament, and upper edge of the
obturator membrane; below it joins the falciform process of

THE ANAL MUSCLES 191

the great sacrosciatic ligament and bounds the ischiorectal
fossa externally. Near its upper margin it gives off the anal or
ischiorectal fascia, which covers the levator ani externally and
bounds the ischiorectal fossa internally.

The fascia of the pyriformis is continued back from the
obturator in front of the pyriformis muscle and sacral plexus.

The rectovesical fascia is attached in front to the back of
the pubis, and laterally separates from the obturator fascia
along a curved line from the upper part of the obturator fora-
men to the ischial spine; this is the posterior part of the white
line which extends from the pubis to the ischial spine. The
fascia, covering the upper surface of the levator ani muscle,
passes to the prostate gland, bladder, rectum, and from side
to side across the median line. The part to the prostate and
neck of the bladder from the pubis consists largely of involun-
tary muscular fibers, the anterior true ligaments of the bladder,
or puboprostatic ligaments; outside them are the lateral true
ligaments, and. the part going to the rectum is the ligament
of the rectum. ‘The anterior part of the fascia meets the bladder
along its junction with the prostate, and divides into two
layers; the upper (ascending) unites with the muscular coat
of the bladder, and is attached just outside the vesiculee semi-
nales; the inferior layer (descending) forms the sheath of the
prostate, and at its apex is continued into the upper layer of
the triangular ligament; it also passes between the bladder
and rectum and forms the front of the sheath of the latter.
The vagina receives the rectovesical fascia in a manner similar
to the prostate.

THE MUSCLES OF THE PERINEUM IN THE MALE

Two groups—anal and genitourinary, comprising a super-
ficial and a deep set in each.

I. The Anal Muscles

The internal or circular sphincter is a thick ring of unstriped
muscle continuous with the circular fibers of the rectum.

The external sphincter, one inch in depth, is elliptical, attached
by a small tendon to the coccyx, encloses the anus, and superficial

192 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

fibers end in skin; some decussate across the median line; a
few deep ones are continuous from side to side, but a large
part blend with the muscles at the “central point.”

The central point of the perineum is the median part of a
tendinous septum in which several muscles meet; it is one inch
in front of the anus, behind the bulb of the urethra; may be
absent.

The levator ani rises from the pubic body, adherent to and
between the obturator and rectovesical fascie, from the “ white
line,’”’ spine of the ischium, and the upper layer of the tri-
angular ligament.

Insertion.—The hinder fibers pass down and in to the coccyx.
The foremost run almost directly back to the “central point,”’
the intervening ones to the lower end of the rectum and median
aponeurosis between the coccyx and anus, common to the two
muscles.

The coccygeus, or levator coccygeus, rises by its apex from the
ischial spine and obturator fascia, and is inserted by its base
into the margin of the coccyx and lower part of the sacrum.
This with the above muscle, on both sides, constitutes the
pelvic diaphragm.

II. The Genitourinary Muscles

Three on each side and a central deep one.

Transversus Perinei.—Origin, low down on inner margin
of the ischial ramus passes forward and inward to unite with
its fellow, the external sphincter, and bulbocavernosus at the
“central point.”

Ischiocavernosus, or Erector Penis.—Origin, inner margin
of the ramus of the ischium, behind and on each side of the
attachment of the crus penis; its tendon spreads over the
crus, and is inserted into the outer and under sides of that
body at its forepart.

Bulbocavernosus, or ejaculator urine, unites with its fellow
in a median raphe continued forward from the “central point,”
the two covering the bulb and part of the corpus spongiosum.
Its fibers ascend from the raphe and end on the dorsum of
the corpus spongiosum by joining its fellow; at the forepart
some pass to the outer side of the corpus cavernosum and
send an expansion over the dorsal vessels; some of the pos-

~>- as
.

—

MUSCLES OF THE PERINEUM IN THE FEMALE 1938

terior fibers unite with the under surface of the triangular
ligament. 7

The above three muscles and enclosed triangular space are
between the superficial and the deep perineal fasciz, 7. e.,
below the lower layer of the triangular ligament.

The constrictor, or compressor urine, rises from the ischio-
pubic rami, from the two layers of the triangular ligament,
between which it is placed, and surrounds the membranous
portion of the urethra, forming a kind of sphincter. A median
raphe sometimes divides the muscle. Its hindermost fibers
have been described as the transversus perinei profundus.

Most of the fibers pass transversely, others obliquely, others
circularly around the urethra, and on the inferior surface is
a longitudinal slip from the base to the apex of the triangular
ligament.

Nerves.—External sphincter by the fourth sacral and inferior °
hemorrhoidal of the pudic, levator ani by the fourth sacral
and perineal branch of the pudic; coccygeus by the fourth
sacral; the three superficial genitourinary muscles by the
perineal branch of the pudic; constrictor urethre by the dorsal
nerve of the penis.

Actions.—Internal sphincter wholly involuntary, eaternal
usually involuntary, but made firmer by act of the will; the
levator ant and coccygeus support and raise the floor of the
pelvis, and thus have to do with forced expiration; the levator
also assists in emptying the lower rectum, raising and expand-
ing its aperture, but some of its fibers act with the external
sphincter in closing the anus; the ftransversi fix the “central
point” and give support to the ejaculator muscles; the zschio-
cavernost compress the crus and help produce and maintain
erection of the penis; the bulbocavernosi forcibly eject fluid
mostly voluntarily at the end of micturition, involuntarily in
the emission of semen; they also are supposed to aid erection
of the penis; the constrictor wrethre assists the bulbocavernosi
in clearing the urethra and erects penis. (Henle).

THE MUSCLES OF THE PERINEUM IN THE FEMALE

In the female, the transversus perinet, eaternal sphineter,
levator ani, erector clitoridis (ischiocavernosus) correspond
13

194 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

to similar muscles of the male, the sphincter vagine to the
bulbocavernosi. The constrictor urethre is the transversus
perinei profundus, and differs from that of the male by being
divided into lateral halves by the vagina.

The Diaphragm (Midriff)

A partition between the abdomen and thorax, rising by
muscular fibers as vertebral, costal, and sternal portions.

The crura, or pillars of the vertebral portion, connected with
the anterior common ligament, rise from the bodies and inter-
vertebral substance of the lumbar vertebrae, the right from
the second, third, and fourth, the left from the second and
third; they arch over the aorta from right to left, and meet
behind it from left to right. The muscular fibers from them
form a figure 8, leaving an opening for the esophagus. ‘The
internal arcuate ligament passes over the psoas muscle from
the outer side of the first lumbar body to the second trans-
verse process. The external arcuate ligament passes over the
quadratus lumborum from the second transverse process to
the last rib; they are the upper margins of fascia covering
those muscles; an arched ligament may pass over both muscles;
muscular fibers of the diaphragm rise from both.

The costal portion rises from the lower six cartilages, inter-
digitating with the transversalis abdominis. The sternal
portion is very short—a single muscular slip, sometimes two,
from the ensiform cartilage.

The central tendon, trefoil, forms the highest part, convex
above, concave below; has three lobes, the right being the
largest, the left the smallest; the tendinous fibers are inter-
woven in every direction.

There are three foramina: The hiatus aorticus, in front of
the first lumbar, transmitting the aorta, thoracic duct, and
vena azygos magnus; the foramen for the esophagus, opposite
the tenth dorsal vertebra, entirely surrounded by muscle,
oval, transmits the esophagus, pneumogastric nerves, and
branches of the coronary artery; the foramen quadratum for
the vena cava is in the highest part of the central tendon, at
the level of the disk between the eighth and ninth dorsal ver-
tebree; its sides are firmly attached to the vein. A sterno-
diaphragmatic ligament passes to this foramen.

FASCIZ AND MUSCLES OF THORACIC REGION 195

Small foramina are in the crura for the splanchnics on both
sides, for the small azygos vein on the left side; the sympathetic
cord perforates the crus or passes under the internal arched
ligament.

There are four weak places: (1) Between the costal and
vertebral portions near the quadratus lumborum; (2) between
the costal and sternal portions = Larrey’s spaces; (3) the
esophageal opening; (4) where the sympathetic cords pierce
the crura. Left side, as a whole, is the weaker; at Larrey’s
space is peritoneum below, then areolar tissue, then pericardium
on the left side and pleura on the right side.

Highest point of the diaphragm on the right side in the
dead body is the level of the fifth rib cartilage with the sternum;
on the left side, of the sixth cartilage with the sternum (Quain);
the midportion is flat, supports the heart, and is nearly immov-
able. A considerable extent of the origin of the diaphragm
is in contact with the thoracic wall.

Relations are, above, pleurze and pericardium, lungs, and
heart; below, peritoneum, liver, stomach, pancreas, spleen,
and kidneys.

Nerves.—Phrenics, lower intercostals, and sympathetic.

Actions.—By its contraction and descent the viscera are
pushed down and thorax lengthened; it elevates the ribs when
its vault is supported by the abdominal viscera; its anterior
fibers oppose forward movement of the sternum.

THE FASCLZ AND MUSCLES OF THE THORACIC REGION

Fascia of Pectoral Region.—Swperficial contains the mammary
gland, sending septa into it and supporting it. These were
called by Sir Astley Cooper the suspensory ligaments. The
deep fascia is thin, covering the surface of the pectoralis major
muscle; it is attached to the middle of the front of the sternum,
above to the clavicle, and below is continuous with the fascia
over the shoulder, axilla, and thorax.. It encloses the space
between the pectoralis major and latissimus dorsi muscles;
it is called in this region the axillary fascia. This latter fascia
sends a prolongation upward under cover of the pectoralis
major muscle, called the deep pectoral fascia.

The costocoracoid membrane or clavipectoral fascia lies beneath

196 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

the clavicular portion of the pectoralis major, bridging in the
interval between the upper border of the pectoralis minor
muscle and the subclavius muscles. Above it splits, and is
attached to the clavicle, one layer in front of the subclavius
muscle, the other layer behind it. Internally it blends with
the fascia covering the first two intercostal spaces, and is
also attached to the first rib, internal to the origin of the sub-
clavius muscle. Externally it is attached to the coracoid
process. This latter portion of the membrane is called the
costocoracoid ligament, extending from the first rib to the
coracoid process and blended with the subclavius muscle.
Below, the costocoracoid membrane splits at the upper border
of the pectoralis minor muscle, invests it, and from the lower
border the single layer is continued downward to join the fascia
covering the biceps muscle and axillary fascia. The cephalic
vein, acromiothoracic vessels, superior thoracic artery, and
external anterior thoracic nerve pierce the costocoracoid mem-
brane. It also sends a slip upward behind the clavicle to
blend with the deep cervical fascia and the sheath of the
axillary vessels.

The Anterior Thoracic Region

M. pectoralis major, two portions, clavicular and sternocostal;
the clavicular portion rises from the inner half of the anterior
surface of the clavicle and sternoclavicular capsule, the sterno-
costal from the sternum (superficial part, Henle), from the
upper six rib cartilages (deep part, Henle) and from the anterior
sheath of the rectus and external oblique aponeurosis. ‘The
fibers converge to be inserted by two tendons, united along
the lower margin, into the external bicipital ridge; the clavic-
ular and upper sternocostal parts form one tendon with straight
fibers; the lower sternocostal part twists so that its lowest
fibers are’ inserted highest; a bursa separates this from the
other anterior tendon. ‘This posterior layer also gives off
three expansions—one over the biceps tendon to the capsule
of the shoulder-joint, one lining the bicipital groove, and one
to the deep fascia of the arm.

1. M. subclavius rises from the groove on the under surface
of the clavicle and recess between the conoid and trapezoid

ee ae ee eae” Ae

THE LATERAL THORACIC REGION 197

ligaments; inserted into the junction of the first rib with its
cartilage between the fibers of the costoclavicular ligament.

2. M. pectoralis minor from three ribs near their cartilages,
usually the third, fourth, and fifth, often the second, third,
and fourth or fifth, and from the intercostal aponeuroses;
insertion, inner border and upper surface of the coracoid;
a bursa is under its insertion (1 in 40 cases).

The Lateral Thoracic Region

M. serratus magnus, placed between the ribs and scapula.
Origin, first eight or nine ribs by’ as many slips; the first slip
is attached to two ribs; insertion, posterior border of the scapula
and into the flat surfaces or anterior aspects of the upper and
lower angles, not in the subscapular fossa. There are three
sets of fibers: (1) First digitation from the first and second
ribs, passes up to the flat area at the upper angle; (2) second
and third digitations, from the second and third ribs, pass
down in a thin triangular layer to the whole line between the
| upper and lower angles; (8) the remaining five or six digita-
m tions converge, some up and some down, to the flat surface
: in front of the lower angle.

Nerves.—The pectoralis major by the two anterior thoracics;
the minor by the internal anterior thoracic nerve; the sub-
clavius by the fifth and sixth cervical; serratus magnus by the
posterior thoracic, upper division by the fifth cervical, middle
by the sixth cervical (often fifth cervical also), lower by the
sixth and seventh cervical.

Actions.—Pectoralis major.

Arm abducted to 90
Arm at side. degrees, Arm raised high.

First part of the Draws the arm for- Draws the arm for-
muscle draws the = ward and rotates ward to horizontal,

arm up and in. in. and no farther.
Second part of the Draws the arm Adducts, and draws

muscle draws the down, in, and down.

arm down and rotates in.

rotates in.

’ It assists the latissimus dorsi in adduction, opposes it in flexion;
the lowest fibers are the best adductors; succeeding ones draw

198 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

forward; used in swimming. Fixed above the _pectorales,
draw the body forward; the major does not draw up the ribs,
the minor does not seem to, so that they have no inspiratory
action.

The subclavius depresses the clavicle or steadies it; may
act in inspiration; supports the sternoclavicular joint. The
pectoralis minor draws the coracoid down and forward, depresses
the shoulder, throws the lower angle of the scapula backward,
acts with the levator and rhomboidei in rotating the scapula.
The scapula is slung by the serratus magnus and rhomboidei,
is kept in equilibrium by them; the lower portion of the serratus,
combined with the trapezius, rotates the scapula on an axis
near its superior angle and elevates the shoulder; the upper
fibers bring the scapula forward and down, assisted by the
pectoralis minor; the whole muscle brings the scapula forward,
acts in all movements of pushing, keeps the scapula pressed
to the ribs; of no importance in respiration; the middle fibers
only might pull ribs down.

THE MUSCLES OF THE THORAX

Mm. intercostales externi, thicker behind than in front,
are directed obliquely downward and forward between the
external lips of the borders of two ribs; they extend from the
tuberosities to the outer ends of the cartilages, not quite reach-
ing them above, but continued along their borders in the lower
two spaces. They are continued to the sternum as anterior
intercostal aponeuroses or ligamenta intercostalia externa.

Mm. intercostales interni, thicker in front, incline down and
back, but less obliquely than the external set; are attached to
the ridge on the inner surfaces of the upper rib and to the
internal lip of the upper border of the lower rib to which it
is attached. Anteriorly they reach the sternum, and the
last two are continuous with the internal oblique muscle;
posteriorly they go to the angles or a little beyond. Their
deficiency behind is supplied by the posterior intercostal apon-
euroses, which merge on one side into the anterior costo-
transversalis ligament, and on the other into a thin fascia
between the muscles.

Mm. infracostales (subcostales) consist of muscular and
aponeurotic fibers, which are attached to the inner surface

THE MUSCLES OF THE THORAX 199

of one rib (usually the lower ribs), and inserted into the inner
surface of the first, second, or third rib below. They are placed
on the inner surface of the ribs, where the internal intercostal
muscles cease.

M. Transversus Thoracis Anticus (triangularis sterni).—
Muscular and tendinous fibers behind the costal cartilages
rise from the ensiform, lower part of the sternum, and the
cartilages of the lower two or three true ribs; the fibers pass
up and out; the lowest are horizontal, the middle oblique,
and the upper ones nearly vertical; inserted to the inner sur-
faces and lower borders of the sixth to the second costal
cartilages, inclusive. It is a continuation upward of the trans-
verse oblique muscle; it may be lacking on one side or both
sides.

Gray includes the diaphragm under the muscles of the thorax
(see page 194).

Nerves.—All by the intercostal nerve.

Actions.—The external intercostals elevate the rib below.
The action of the internal intercostals is not definitely settled
Haller early taught that they were accessory muscles of inspira-
tion. Others that they are expiratory muscles. During
operations for removal of the breast, when they can be seen
under forced respiration, their actions seemed to be negative so
far as accessory muscles of respiration were concerned. (Little.)
Costal and diaphragmatic respiration are normally combined;
the thorax is increased anteroposteriorly by a forward move-
ment of the sternum, transversely by elevation and eversion
of the ribs, vertically by the descent of diaphragm; extension
of the vertebral column is alsoan agent. ‘There are three views
‘as to the action of the intercostals: Hamberger’s, that the
external elevate and the internal depress the ribs; Hutchinson’s,
that the external and anterior parts of the internal elevate, and
the rest of the internal depress ribs; Haller’s, that (1) the ribs
are not joined as by a pivot to the vertebral column; (2) are not
parallel bars, but curved arches; (3) no two ribs can move as
they please, being connected above and below, but all move as
a system; if fixed point be above, both the external and internal
intercostals elevate the ribs and are inspiratory muscles; fixed
below, they both depress and assist expiration.

-

200 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

MUSCLES AND FASCIA OF THE UPPER
EXTREMITY

MUSCLES AND FASCLH OF THE SHOULDER AND ARM

The Acromial Region

The deep fascia is strong and tendinous over the back of
the deltoid and infraspinatus; the infraspinatus fascia covers
the teres minor and splits at the posterior border of the deltoid,
a deep layer passing to the shoulder-joint under that muscle, a
superficial layer to the spine of the scapula over the muscle.

M. Deltocdeus—Origin, in three portions; an anterior from
the front of the outer third of the clavicle, a middle from the
point and outer edge of the acromion, a posterior from the
lower border of the scapular spine and triangular surface
at its inner end, and from the infraspinatus fascia. These
converge into the tendon of insertion into the deltoid tubercle
of the humerus. The anterior and posterior parts run by
long fasciculi into the marginal parts of the tendon; in the
acromial portion most fibers rise in a bipenniform manner
from the sides of four tendinous septa; the oblique fibers are
inserted below into three septa which come up from the humerus
to alternate with those above. Some fibers pass from the tip
of the acromion to the tips of the lower septa, and some from
the tips of the upper septa directly to the humerus.

The Posterior Scapular Region

1. M. supraspinatus, from inner part of the supraspinous
fossa to region of the notch, from supraspinous fascia and
transverse ligament; adherent to capsule and infraspinatus
tendon; inserted into the upper of the three facets on the great
tuberosity of the humerus.

2. M. infraspinatus, rises from the inner two-thirds of the
infraspinous fossa, from the infraspinatus fascia, and under
surface of the spine; fibers converge to a tendon concealed
within the muscle and inserted into the middle facet of the
great tuberosity. It may be inseparably connected with the
teres minor.

THE ANTERIOR SCAPULAR REGION 201

3. M. Teres Minor.—Origin, from narrow grooved surface
or dorsum of the scapula close to the axillary border, from
septa between it, the teres major, and infraspinatus; inserted
into the lowest facet on the great tuberosity and into the
shaft for a short distance below.

May be a bursa under its insertion. It is behind the long
head of the triceps and capsule; the dorsal scapular artery
passes between it and bone.

4. M. Teres Major.—ls a thick somewhat flattened muscle.
Origin, from the oval surface on the back part of the inferior
angle of the scapula, and the fibrous septa common to it, and
the teres minor and infraspinatus; inserted, by a flat tendon
into the inner ridge of the bicipital groove of the humerus.

The Anterior Scapular Region

M. Subscapularis.—Origin, by muscular and_ tendinous
fibers from the venter of the scapula and groove along the
axillary border; insertion, small tuberosity of the humerus
and into the shaft for a short distance. As in the deltoid, this
muscle contains two sets of septa—one from the origin, and
one from the insertion for attachment of the oblique muscular
fibers. ‘Some fibers from the axillary border of the muscle
are usually inserted into the capsule, known as the subscapularis
minor. ;

There is a bursa between the muscle and the capsule, and
often another on its anterior surface (bursa coracobrachialis).

Nerves.—Supraspinatus and infraspinatus by the supra-
scapular nerve from the fifth and sixth cervical; others from
the posterior cord of the brachial plexus, deltoid, and teres
minor from the fifth and sixth cervical through the circum-
flex nerve; subscapularis by the fifth and sixth cervical through
the upper and lower subscapular nerves.

Actions.—Deltoid abducts arm to 90 degrees, posterior
fibers said to abduct only to 45 degrees; insertion of the trape-
zius corresponds to origin of the deltoid, so that the two are
continuous in action; anterior part of the deltoid draws the
humerus forward and rotates in; of both deltoids crosses the
arms over the chest; posterior part draws the humerus back-
ward and rotates out; supraspinatus, infraspinatus, and sub-
scapularis steady the capsule while the deltoid acts. The

202 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

supraspinatus only abducts. The infraspinatus rotates out
and carries the arm back when it is raised. The subscapularis
rotates in and carries the arm forward when it is raised. The
-teres minor rotates the raised humerus out and depresses it.
All act as accessory ligaments to the joint. The teres major
assists the latissimus dorsi in lowering the humerus, when
raised, also acting as an internal rotator of the shoulder-joint.

THE MUSCLES AND FASCIA OF THE ARM

The aponeurosis of the arm (deep fascia) is thin over the
biceps, strong over the triceps, and is attached to the humerus
intermuscular septa (ligamenta intermuscularia). The external
intermuscular septum extends from the outer epicondyle and
supracondylar ridge to the deltoid insertion; it is pierced by
the musculospiral nerve and superior profunda artery. The
internal intermuscular septum extends from the inner epicondyle
and inner supracondylar ridge to behind the coracobrachialis;
it is pierced by the anastomotica magna artery.

The internal brachial ligament of Struthers is a fibrous band
below the teres major insertion to the inner epicondyle; the
ulnar nerve and inferior profunda artery pass between this
band and the internal intermuscular septum.

The Muscles of the Anterior Humeral Region

M. Biceps Flexor Cubiti (brachii).—Its short or inner head
rises with the coracobrachialis from the tip of the coracoid
process; the long head, from the upper end of the glenoid cavity
within the capsule by a tendon continuous on each side with
the glenoid ligament; these two heads form a belly in the
middle and lower part of the arm. ‘The tendon of insertion is
slightly twisted and attached to the back part of the tuberosity
of the radius, separated from the forepart by a bursa. A
second bursa may be between the tendon and ulna. From
the inner side of the tendon a part branches off as an aponeurotic
band or bicipital fascia, p. n., and blends with the. deep fascia
of the forearm stretched across the brachial vessels and median
nerve.

M. Coracobrachialis.—Origin, tip of the coracoid between
the pectoralis minor and short head of the biceps, conjoined

MUSCLES OF THE POSTERIOR HUMERAL REGION 208

with the latter; insertion, inner border and inner surface of
the humerus near its middle, between the triceps and the
brachialis anticus; higher up some of its fibers are often inserted
into a fibrous band arching over the latissimus dorsi and teres
major tendons, and attached close to the small - tuberosity.
It is usually pierced by the musculocutaneous nerve.

Many varieties which seem to indicate it are formed of three
parts, viz.: (1) A superior short part, from the coracoid to
small tuberosity (M. coracocapsularis) to the capsule; (2)
middle part, corresponding to the muscle usually seen; (3)
inferior part, to the inner epicondyle or supracondylar process
(coracobrachialis minor). The middle part is most constant
in man, but is usually accompanied by a part of the third,
with the musculocutaneous nerve between them. It may
send a slip to the brachialis anticus or internal septum or
internal brachial ligament.

M. brachialis anticus (brachialis internus, p. n.) rises from
the lower half of the front of the humerus, nearly the whole
of the internal intermuscular septum, and upper part of the
external; it embraces the deltoid insertion by two processes,
the outer of which is in the spiral groove as far as the upper
limit of the deltoid tubercle. It is adherent to the capsule of
the elbow-joint, and often sends a slip into it, and is inserted
into the inner part of the rough surface at the junction of the
coronoid process with the shaft of the ulna and to a part of
the tubercle of the ulna.

The Muscles of the Posterior Humeral Region

M. extensor or triceps extensor cubitt occupies the whole
posterior brachial region. ‘Three heads are inserted into a
common tendon occupying the posterior surface of the muscle
from the middle of the arm to the elbow. The middle or long
head (anconeus longus—anconeus was a term applied to any
muscle attached to the olecranon) rises from the inferior glenoid
tubercle of the scapula and adjacent portion of the axillary
border; this forms the middle and superficial part of the muscle
and ends on the inner margin of the tendon. The eaternal
head (anconeus brevis) rises above the spiral groove and from
an aponeurotic arch of the external intermuscular septum
as it crosses it, extending to the teres minor insertion above,

204 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

and inserted into the upper end and outer border of the tendon.
The internal or deep head (anconeus internus) rises from the
whole posterior surface of the humerus below the spiral groove,
from the lower part of the external intermuscular septum,
from the whole of the internal, as high as the teres major;
some of its fibers are inserted directly into the olecranon,
but most join the deep surface of the tendon. The common
tendon is inserted into .the tuberosity of the olecranon, and
externally a band is prolonged over the anconeus to the fascia
. of the forearm and posterior border of the ulna; it may send
a slip to the capsule.

On removing the triceps a few muscular slips are sometimes
found from the bone to the capsule, analogous to the sub-
crureus, and described by some as distinct from the triceps,
called the subanconeus.

There is a bursa between the tendon and olecranon or in
the tendon, sometimes one between the integument and tendon,
rarely one between the tendon and ulnar nerve (retroepitroch-
lear).

Nerves.—Coracobrachialis and biceps by the musculocuta-
neous (fifth and sixth cervical), the brachialis anticus by the
musculocutaneous, triceps by the musculospiral (seventh and
eighth cervical).

Actions.— Biceps flexes the arm at the shoulder and the
forearm at the elbow; after pronation of the forearm it is a
powerful supinator and makes tense the fascia of the forearm;
its inner head and coracobrachialis draw the arm in as well
as up. The brachialis anticus is a simple flexor at the elbow.
Triceps, internal and external heads are extensors at the elbow; |
the long head extends the arm on the scapula, keeps the head
of the humerus in place, and assists in extending the forearm.
These muscles may act from distal fixed points, as in climbing.

MUSCLES AND FASCLE OF THE FOREARM

The superficial fascia is most distinct at the elbow, contains
- the superficial veins, and below connects the skin with the
palmar fascia.

The aponeurosis of the forearm (deep fascia) is composed
largely of transverse fibers, strengthened by expansions from

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THE ANTERIOR RADIOULNAR REGION 205

the condyles of the humerus, olecranon, and fascia over the
biceps and triceps. The anterior part is weaker than the pos-
terior,“and continuous below into the anterior annular ligament
(ligamentum carpi volare, p. n.); it sends in a thin layer between
the superficial and deep muscles. The posterior portion sends
off septa between the muscles and forms the posterior annular
ligament (ligamentum carpi dorsale, p. n.). The tendon of
the palmaris longus muscle is the only one passing in front
of the anterior annular ligament.

The Anterior Radioulnar Region

Eight muscles, five superficial and three deep.

Superficial Layer.—All from a common tendon in the follow-
ing order from without in:

1. M. pronator teres rises by two heads, the larger from the
upper part of the inner condyle above the common tendon
and from the common tendon and intermuscular septum;
second head, thin and deep, from the inner margin of the
coronoid process; insertion, by a flat tendon on the middle
of the outer surface of the radius. The ulnar artery is beneath
this muscle, and the median nerve between its heads.

2. M. flexor cary radialis (M. radialis internus) rises from
the common tendon and septa between it and the pronator
teres, palmaris longus, and flexor sublimis; tendon begins
below the middle of the foréarm, passes through a special
compartment of the anterior annular ligament through a groove
in the trapezium; inserted into the base of the second meta-
carpal bone, anterior surface, and usually by a small slip to
the base of the third.

3. M. palmaris longus is placed between the ulnar and radial
flexors of the carpus, resting upon the flexor sublimis; rises
from the common tendon, fascia, and septa, forming a short
muscular belly ending in a slender tendon, inserted into the
palmar fascia, and sends a slip to the abductor pollicis, some-
times one to the little finger muscle.

Most variable muscle of the body, lacking on both sides
in one-third of the cases, on one side in one-half of the cases

‘(Hallett). Muscular belly may occupy the middle of the ten-

don, lower end, both ends, or be absent; may be double or
have additional origin from the coronoid or the radius. Inserted

206 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

Fra. 32

(Testut.)

Superficial muscles of front of right forearm.

THE ANTERIOR RADIOULNAR REGION 207

into the fascia of the forearm, flexor carpi ulnaris, pisiform,
scaphoid, or little finger muscles. This muscle with the central
part of the palmar fascia was a superficial flexor of the fingers,
but has been reduced by the development of the other flexors.

4. M. flexor carpi ulnaris (M. ulnaris internus) is the inner-
most of the superficial group; rises by two heads, one from the
common tendon, and one from the inner side of the olecranon
and upper two-thirds of the posterior border of the ulna by
an aponeurosis common to it, the flexor profundus digitorum
and the extensor carpi ulnaris; muscular fibers end in a tendon
which occupies the anterior margin of the lower half of the
muscle; posteriorly the muscular fibers continue down to within
an inch of its insertion; inserted into the pisiform, by a small
band to the anterior annular ligament, and prolonged by the
pisometacarpal and pisouncinate ligaments to the fifth meta-
carpal and unciform.

The ulnar nerve and posterior ulnar recurrent artery pass
between its two heads; the pisiform throws this tendon for-
ward, so that the ulnar pulse connot be felt so well as the
radial.

5. M. flexor sublimis digitorum (perforatus), placed behind
the preceding, rises by three heads: (1) Inner condyle by
the common tendon, fibrous septa, and internal lateral liga-
ment; (2) internal margin of the coronoid; (3) anterior oblique
line of the radius; divided below into four parts ending in
tendons inserted into the mesial phalanges of the four inner
digits. Through the annular ligament they are placed in pairs;
the anterior pair are for the ring and middle fingers, the posterior
for the index and little fingers. In the palm they diverge and
enter a sheath with the flexor profundus; opposite the bases
of the proximal phalanges the tendon divides and folds around
the deep flexor, and is reunited behind it; the two portions
again separate and pass on each side to the middle of the lateral
border of the second phalanx.

The Deep Muscles.—1. M. flexor profundus digitorum (per-
forans).—Origin, the upper three-fourths of the inner and
anterior surface of the ulna, from not quite the ulnar half
of the interosseous membrane for the same distance, and
from an aponeurosis attached to the posterior border of
the ulna, common to it, the flexor and extensor carpi
ulnaris. Only one tendon (for the index finger) separates

208 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

above the wrist; in the palm, as the tendons diverge, they
give origin to the lumbricales; over the proximal and mesial
phalanges the tendon is bound down by an osseoaponeurotic
sheath, and opposite the proximal phalanx it passes through

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MEDIAN NERVE

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Synovial membranes of tendons in the palm, Tendon of flexor sublimis
artificially distended. (Testut.) perforated by tendon of
flexor profundus. (Testut.)

an opening in the flexor sublimis tendon, and is finally inserted
by an expanded end into the base of the distal phalanx; over
the middle and distal phalanx its tendon is marked by a longi-
tudinal furrow or cleft.

THE ANTERIOR RADIOULNAR REGION 209

The index finger portion is usually separate throughout,
and comes mostly from the interosseous membrane; between
the ring and little finger portions a considerable part of the
inner surface of the ulna is free from muscular attachment.

The sheaths of the flexor tendons are opposite the proximal
and middle phalanges, and formed of strong transverse bands,
ligamenta vaginalia; opposite the joints the bands change into
a thin membrane, strengthened by oblique decussating fibers,
so that there are annular or transverse fibers, and crucial or
oblique. ‘The sheath has a synovial lining containing small
folds, vincula tendinum or ligamenta mucosa, passing between
the tendons and bones. There are two sets—ligamenta brevia,
broad, four-sided, and membranous, passing between both
the superficial and the deep tendons near their insertions
and the lower part of the phalanx just above the joint capsule;
the ligamenta longa, less constant, join the tendons at a higher
level. Contained in the ligamentum breve of the deep flexor
. is a small band of yellow elastic tissue, ligamentum subflavum,
passing from the tendon to the head of the second phalanx.

2. M. flexor longus pollicis rises from the anterior surface
of the radius, below its oblique line to the edge of the pronator
quadratus, and from the adjacent part of the interosseous
membrane, and usually (27 out of 36 cases) receives a slip
(fasciculus exilis) from the inner epicondyle or coronoid. The
tendon passes between the sesamoid bones of the thumb and
enters a canal similar to that of the other flexors, to be inserted
into the base of the distal phalanx of the thumb. Its com-
plete separation from the flexor profundus is characteristic
of man.

3. M. pronator quadratus, just above the wrist, close to the
bones behind the last two muscles, quadrilateral and flat,
arises from the pronator ridge and inner part of the anterior
surface of the ulna for the lower fourth, and from the inferior
from the radiocarpal joint; inserted into the anterior surface
and anterior margin of the shaft of the radius for a little less
than its fourth.

Nerves.—Six and one-half of the above muscles by the
median nerve, one and one-half by the ulnar. Pronator teres,
flexor carpi radialis, palmaris longus, and condyloulnar head -
of the flexor sublimis receive median branches near the elbow;
radial head of the flexor sublimis and belly for the index finger

14

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210° MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

have separate twigs; the flexor longus pollicis, pronator quad-
ratus, and outer half of the flexor profundus by the anterior
interosseous branch of the median. Flexor carpi ulnaris and
inner half of the flexor profundus by the ulnar.

The Radial Region

Three in number, from the lower third of the arm and upper
third of the forearm in an almost continuous row.

1. M. supinator longus (brachioradialis) rises from the
upper two-thirds of the external supracondylar ridge of the
humerus and external intermuscular septum, limited above
by the spiral groove; thin fleshy belly ends at the middle of
the forearm in a flat tendon which expands at its insertion
into the outer side of the radius at the base of the styloid
process; its inner edge is united by fascia to the flexor carpi
radialis; it sends some fibers to the aponeurosis on the back
of the forearm.

2. M. extensor carpi radialis longior rises from the lower
third of the external supracondylar ridge and external inter-
muscular septum and a few fibers from the common tendon;
inserted into the radial half of the dorsal surface of the base
of the second metacarpal.

3. M. Ezatensor Carm Radialis Brevior—Origin, by the
common extensor tendon from the outer condyle, septa, external
lateral ligament, fascia, and a fibrous arch over the radial
nerve and radial recurrent vessels; insertion, into the radial
half of the dorsal surface of the base of the metacarpal bone
of the middle finger.

These tendons are crossed by the tendons of the first two
thumb extensors a little above the wrist.

The Posterior Radioulnar Region

Two layers, muscles of the superficial layer inserted into-

the ulnar edge of the forearm and hand and into the fingers
from the fifth to the second inclusive; of the deep layer into
the radial edge of the forearm and hand and two outer fingers.

SuPERFICIAL LAyEeR.—1. M. Eatensor Communis Digitorum.
—Origin (from neither ulna nor radius), common extensor

tendon from the external condyle of the humerus, orbicular

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RID SPY

THE POSTERIOR RADIOULNAR REGION 211

ligament, fascia, and septa; there are three fleshy bellies, the
innermost divided into two, four passing under the posterior
annular ligament; the first and second pass to the index and
middle fingers connected by a weak band, always transverse;
the first is joined by the extensor indicis tendon at the meta-
carpophalangeal joint; the third runs to the ring finger and
sends a slip to the middle finger tendon; the fourth divides,
the outer larger part going to the ring finger, the inner part
joining the outer division of the extensor minimi digiti tendon;
this fourth is the smallest tendon, and receives muscular fibers
as far as the wrist.

Opposite the metacarpophalangeal joints the tendons are
bound down by transverse fibers from the front of the joint,
ligamenta dorsalia; the tendon expands, is joined by a slip
from the interossei, and on the radial side by the insertion of
a lumbrical muscle, forming a broad aponeurosis, which divides
at the lower part of the first phalanx into three slips—a central |
thin one for the base of the second, while the two lateral parts
join and are inserted into the base of the last phalanx.

2. M. extensor minimi digiti (extensor digiti quinti proprius)
rises from the superficial and deep fascia of the forearm, from
the orbicular ligament, from the septa between it and common
and ulnar extensors; its tendon is in a groove between the
radius and ulna, and splits into two on the back of the hand,
the outer being joined by a slip from the fourth common ex-
tensor tendon, and both parts end on the little finger, like
the other extensor tendons.

3. M. Extensor Carpi Ulnaris (ulnaris externus).—Origin,
common tendon, orbicular ligament, septa, fascia of the fore-
arm, which is connected with the elbow-joint capsule, and
anconeus; its belly in its middle third is bound to the posterior
border of the ulna by aponeurosis, and may receive fibers from
this fascia; insertion, tuberosity of the base of the fifth meta-
carpal. A bursa is under its tendon of origin in one-fourth
of the cases.

In 52 per cent. of the cases a slip is continued anteriorly
over the opponens minimi digiti to the fascia over that muscle,
to the metacarpal bone or first phalanx of the little finger
(analogue of the peroneus brevis of the little toe).

4. M. anconeus (quartus) fills the space between the triceps
and extensor carpi ulnaris; is flat and triangular, covered by

212 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

fascia connected with the triceps; rises by a narrow tendon
from a fossa on the inner and posterior part of the external
condyle; upper fibers are transverse, the rest pass obliquely
down and in to the radial aspect of the olecranon and adjacent
upper third of the ulna. As a rule, its superior fibers are con-
tinuous with those of the internal head of the triceps. A
bursa is found under its tendon of origin, not in children.

Deep Layer.—l. M. Supinator Brevis —Origin, external
lateral ligament, orbicular ligament, supinator ridge, oblique
line of the ulna, and for a short distance on the outer border
of the ulna, from the fascia covering it, which is connected
with the external condyle; it regularly consists of two layers
separated by the posterior interosseous nerve; the superficial
one rises by aponeurotic fibers, the other by muscular. The
fibers pass sling-like around the upper part of the radius to
_ be inserted into a third of its length, limited by the anterior
and posterior oblique lines, to its neck and elbow-joint capsule.

Anterior fibers may have insertion into the biceps tendon
or tuberosity of the radius.

2. M. Extensor Ossis Metacarpi Pollicis (abducens pollicis
longus).—Origin, upper part of the outer division of the pos-
terior surface of the ulna below the supinator brevis, from
the middle third of the posterior surface of the radius and inter-
osseous membrane between. Its tendon passes over those of
the radial extensors, and is inserted into the radial side of the
base of the metacarpal bone of the thumb, and commonly by a
slip into the trapezium, its tendon usually splitting.

3. M. extensor longus pollicis (extensor securidi internodii
pollicis) rises below the extensor ossis on the middle third of
the ulna and from the interosseous membrane for about 1
inch; its tendon passes over the radial extensors, and is inserted
into the dorsal aspect of the base of the distal phalanx of the
thumb. There is a tendency for it to divide into three parts,
as in case of the extensor communis tendons, but all three
converge to the base of the distal phalanx.

4. M. Extensor Indicis Proprius (M. indicator).—Origin,
from the ulna below the extensor longus pollicis, and slightly
from the interosseous membrane and fascia over the extensor
carpi ulnaris; unites with the common extensor tendon for
the index, and forms the usual insertion. This and the extensor

THE POSTERIOR RADIOULNAR REGION 213

ininimi digiti tendon are always on the ulnar side of the respec-
tive common extensor tendons.

Fig. 35

ANTERIOR
ANNULAR
LIGAMENT, y
FLEXOR LONGUS POLLICIS. Median nerve.
FLEXOR CARP! RADIALIS. Ulnar vessels.
MUSCLES OF THUMB. PALMARIS BREVIS.

SSE FES |] Mets. Sree eS BH //EXT. CARPI
EXTENSOR SS@ WY 42 i mE /7~ ULNARIS.

Trapezium.

EXT. CARP. RAD. LONG EXTENSOR

Trapezoid, COMMUNIS
DIGITORUM
EXTENSOR CARP! RADIALIS cXTERAOR INDICS.
BREVIOR.

Os magnum.

Transverse section through the carpus, showing the relative positions of the
tendons, vessels, and nerves. (Henle.)

5. M. Extensor Brevis Pollicis (extensor primi internodii
pollicis).—Origin, small part of the interosseous membrane
and radius below the middle, next below the extensor ossis;
insertion, proximal end of the proximal phalanx of the thumb
on its dorsal aspect. .

Nerves.—For the radial and posterior groups wholly by the
‘musculospiral; the anconeus, supinator longus, and extensor
carpi radialis longior by that nerve before it divides; all the
others by its posterior interosseous branch.

Three nerves, therefore, supply all the muscles of the fore-
arm—median and ulnar anteriorly (flexor carpi ulnaris and
inner half of the flexor profundus by the ulnar), musculospiral
externally and posteriorly.

214 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

THE MUSCLES AND FASCLE OF THE HANDS

Fascia of the dorsum is a thin layer prolonged from the
posterior annular ligament and blending with the extensor
expansions over the fingers; deeper than this the interossei
are covered by thin aponeuroses.

Fascia of the palm (volar aponeurosis) consists of a strong
central part and two lateral portions which cover the short
muscles of the thumb and little finger. The céntral portion
is the part commonly called the palmar fascia; it consists of
fibers mostly prolonged from the palmaris longus, some from
the annular ligament, thus forming two superficial layers
with vertical fibers, between which is the palmaris brevis
muscle; there is a deep layer of transverse fibers. Below, the
fascia divides into four processes to join the digital sheaths;
offsets are sent back to the deep transverse ligament at the
heads of the metacarpals, forming a short canal above each
finger for the flexors. Between the processes the transverse
layer of fascia covers the lumbrical muscles, digital vessels,
and nerves, passing over to the thumb and forefinger. At the
clefts of the fingers a transverse band is called the superficial
transverse ligament, or Gerdy’s fibers. The interossei muscles
also have a separate fascia continued below into the deep
transverse ligament.

The Muscles of the Dorsal Surface

Extensor tendons already described.
Derr Muscies.—Median Carpal Bures.—As the super-

ficial and deep flexors and flexor longus pollicis enter the hollow '

of the hand they are bound into one tube lined by synovial
tissue; a loose synovial sac is formed, passing up to the level
of the radiocarpal joint and prolonged down the inner tendons
to the digital sheath of the little finger, opening into it generally.
The sheath for the tendon of the thumb is generally separated
from the large sac by a sagittal septum behind the median
nerve; the bursa extends but a short distance on the index
and middle finger tendons.

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THE RADIAL REGION 215

The Radial Region

The following muscles constitute the thenar eminence and have
a great variety of description. (See Quain and Henle.)

1. M. Abductor Pollicis (brevis).—Origin, front of the annular
ligament, ridge of the trapezium or tuberosity of the scaphoid;
insertion, base of the proximal phalanx of the thumb, radial
border, and sends a slip to the extensor tendons. (Henle
calls this one belly, and what is described below as the outer
head of the flexor brevis he calls the other belly of the abductor.)

2. M. Flexor Brevis Pollicis—Outer or superficial head
rises from the outer two-thirds of the annular ligament,
inserts on the outer side of the base of the proximal phalanx,
having a sesamoid bone developed in it; inner or deep head
is very small, and between the adductor obliquus and outer
head of the first dorsal interosseous; rises from the ulnar side
of the first metacarpal; inserted into the inner side of the base
of the proximal phalanx.

3. M. adductor pollicis Quain describes in two parts, separated
by the radial artery as it enters the palm. The adductor
obliquus pollicis (caput obliquum, p. n.), largest of the thumb
muscles, rises from the upper ends of the second and third
metacarpals, os magnum, anterior carpal ligaments, and
sheath of the flexor carpi radialis; it passes on the inner side
of the long flexor tendon to insert on the inner side of the base
of the proximal phalanx, uniting with the adductor trans-
versus and deep head of the flexor brevis. The inner sesamoid
bone is developed in it. A considerable fasciculus passes behind
the long flexor to join the superficial head of the flexor brevis
and outer sesamoid bone. (This muscle is usually described
as the inner head of the flexor brevis.)

4. The adductor transversus pollicis (caput transversum,
p. n.) rises from the lower third of the front of the third meta-
carpal bone; inserted into the inner side of the base of the
proximal phalanx of the thumb, and the common insertion
sends a slip to the long extensor.

5. M. opponens pollicis beneath the abductor, rises from
the annular ligament and outer side of the ridge of the trape-
zium; inserted by an upper layer into the whole length of the
first metacarpal bone, radial border, and by its deeper layer
into the head of the bone and radial part of its palmar surface.

216 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

The Ulnar Region

The following muscles constitute the hypothenar eminence.

1. M. abductor minima digiti (abductor digiti quinti) rises
from the lower border and inner surface of the pisiform, almost
a continuation of the flexor carpi ulnaris; insertion, base of
the proximal phalanx of the little finger, ulnar side, and into
a sesamoid bone, sending a slip to the extensor tendon.

2. M. flexor brevis minimi digiti is separated from the abductor
by deep branches of the ulnar nerve and artery, and rises
from the annular ligament and tip of the unciform process;
inserted into the base of the proximal phalanx by means of
a tendinous arch passing over the flexors, attached to the radial
and ulnar borders of the base. May be absent or fused with
abductor.

3. M. opponens minimi digiti rises from the annular liga-
ment and unciform process to insert on the whole length of
the ulnar side of the fifth metacarpal and anterior surface of
its head.

4. Palmaris brevis is a thin quadrilateral muscle placed
beneath the integument on the ulnar side of the hand. It
arises by tendinous fasciculi from the anterior annular liga-
ment and palmar fascia; passing inward it is inserted into the
skin on the inner border of the palm of the hand.

The Middle Palmar Region

The dorsal interossei are four in number, one for each space,
not rising above the level of the bones, and numbered from
without inward. Each rises from the two bones between which
it is placed, most extensively from that supporting the finger
upon which it acts. The tendon is inserted partly into the
base of the proximal phalanx and partly into the extensor
tendon. Each abducts its finger from the middle line; two
are inserted into the middle finger, one on either side, one
into the radial side of the index, and one into the ulnar side
of the ring. The first dorsal interosseous is larger than the
others, called the abductor indicis; its outer head comes from
the proximal half of the ulnar border of the first metacarpal,
its inner from the whole length of the radial border of the
second metacarpal.

THE MIDDLE PALMAR REGION 217

The palmar interossei are three in number, are adductors,
and each rises from the lateral surface of the metacarpal of
the finger on which it acts. They terminate like the dorsal
tendons. ‘The first belongs to the ulnar side of the index,
the second and third to the radial sides of the ring and little
fingers.

The lumbricales are four small muscles, not always wells
defined. ‘They rise from the tendons of the flexor profundus
digitorum; the first and second, from the radial side and palmar
surface of the tendons of the index and middle fingers respec-
tively; the third from the adjoining sides of the tendons of
the middle and ring fingers; and’ the fourth from the adjoining
sides of the tendons of the ring and little finger. They pass to
the radial side of the corresponding fingers and opposite the
metacarpophalangeal articulation; each tendon is inserted into
the tendinous expansion of the extensor communis digitorum,
covering the dorsal aspect of each finger.

Nerves of Hand Muscles.—Abductor pollicis, opponens pollicis,
outer head of the flexor brevis pollicis, and outer two lumbri-

_cales are supplied by the median nerve. The palmaris brevis,
muscles of the little finger, inner two lumbricales, all the inter-
ossel, adductores pollici, inner head of the flexor brevis pollicis,
are supplied by the ulnar nerve.

Actions of Muscles of the Forearm and Hand.—Pronation
by the pronator teres and quadratus and flexor carpi radialis
slightly; pronator teres flexes the forearm; can only pronate
when the radius is intact.

Supination by the supinator brevis, biceps, and supinator
longus; the latter is a flexor of the elbow and brings the forearm
into midsupination. Radial extensors of the wrist flex the
elbow; others from the external condyle extend. Flexion
of the wrist by the flexor carpi ulnaris and radialis, by the
flexors of the fingers and palmaris longus.

Extension of the wrist by the extensor carpi ulnaris, the two
radial extensors, and extensors of the fingers.

Abduction of the wrist by the radial flexor and radial extensors
and extensors of the thumb.

Adduction of the wrist by the flexor and extensor carpi ulnares.
The flexor carpi radialis and extensor carpi ulnaris act on the
radiocarpal joint; the flexor carpi ulnaris and radial extensors on
the midecarpal joint.

918 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM 4

The extensors of the wrist are moderators of the long flexors
of the fingers; the flexors of the wrist are modérators of the
extensors of the fingers.

The dorsal interossei abduct the fingers from the middle
one; the palmar adduct; the interossei and lumbricales flex
the first phalanx and extend the last two.

Flexion in the Fingers. Extension in the Fingers:
First phalanx, by the inter- By the extensor communis.
ossei and lumbricales.
Second phalanx, by the flexor By the interossei and lumbri-

sublimis. cales.
Third phalanx, by the flexor - By the interossei and lumbri-
profundus. cales.

When we flex the fingers they tend to approach, due to lateral
ligaments and obliquity of the tendons.

The palmaris longus makes tense the palmar fascia, feebly
flexes the forearm and wrist; all the muscles from the condyle
feebly flex the forearm.

Palmaris brevis wrinkles the skin over the hypothenar emi-
nence and protects the ulnar vessels and nerve from pressure
when a foreign body is grasped.

Extension in the thumb is in the plane of abduction of the
fingers, and its abduction is a movement forward. The action
of its muscles and those of the little finger are indicated by
their names; the flexors of the first phalanx in either case
also extend the last, as the interossei would. The ulnar extensor
and flexor of the carpus are moderators of the thumb extensors.
There are three flexors of the wrist (including the palmaris
longus) and three extensors, three flexors of the fingers and
three extensors, three flexors of the thumb and three extensors.

THE MUSCLES AND FASCLE OF THE LOWER ©
EXTREMITY

FASCIZ OF THE THIGH

The superficial fascia is continuous with that of other parts
of the body. Thick over gluteal region, passes over Poupart’s

Tee ae

PASCIA OF THE THIGH 219

ligament to the abdomen and inward above into the dartos
of the scrotum and superficial fascia of the perineum. A deep
layer of this fascia is continued across the saphenous opening,
perforated by vessels and lymphatics, eribriform fascia.

The deep fascia or fascia lata is a strong membrane forming
a continuous sheath around the limb; it is attached above to
the back of the sacrum and coccyx in the median line, to the
crest of the ilium, Poupart’s ligament, body and rami of the
pubis, ramus and tuberosity of the ischium, and lower margin
of the great sacrosciatic ligament. It descends on the gluteus
medius as far as the upper border of the gluteus maximus,
which muscle it encases, and over the great trochanter a great
part of the muscle is inserted between its layers. Fr-m the
forepart of the iliac crest to the outer tuberosity of the tibia
is the ilotibial band, which receives the tensor vaginze femoris
and gluteus maximus insertions.

The fascia is thinnest at the inner part of the thigh over
the abductors, and strengthened on each side of the patella
by expansions from the vasti. Posteriorly it is continuous
over the hamstrings and popliteal space.

On the front of the thigh, below the inner end of Poupart’s
ligament, is the saphenous opening, bounded externally by
the faleiform border (ligament of Burns), more distinctly curved
above and below as the swpertor and inferior cornua. The
inner extremity of the superior cornu passes to the inner side
of the femoral sheath and to Gimbernat’s ligament; it is the
femoral ligament (Hey).

‘The parts external and internal to the saphenous opening
are the iliac and pubic portions; the line is connected above
with Poupart’s ligament and the deep layer of superficial
fascia (of Scarpa), and internally forms the falciform margin
of the saphenous opening.

The pubic portion, or pectineal fascia, is attached above
to the iliopectineal line, passes behind the femoral vessels,
closely connected with the sheath, and merges into the iliac
fascia and capsule of the hip.

The fascia lata has various deep processes; one is internal
to the tensor vagine femoris on the surface of the vastus _
externus.

There are external and internal intermuscular septa inserted
_into the linea aspera.

220 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

The common femoral vessels are surrounded by the funnel-
shaped crural sheath, made of transversalis fascia in front and
iliac fascia behind; it is divided into three compartments—
outermost for the artery, middle one for the vein, and inner-
most contains a lymphatic gland and fat, and when distended
by a femoral hernia is the crural canal, $ to 12 inches (14 to
34 mm.) long. The crural ring (upper opening of the canal)
is closed by the septum crurale.

THE ILIAC REGION

1. M. Quadratus Luwmborum.—A quadrilateral muscle placed
between the last rib and the pelvis. Origin, iliolumbar liga-
ment, external lip of the crest of the ilium for 2 inches, from
two, three, or four lumbar transverse processes by fleshy slips
passing up anteriorly (Gray says this is a separate portion);
insertion, inner half of last rib and upper four lumbar trans-
verse processes.

Nerves.—Last dorsal and upper lumbar.

Actions.—Lateral flexor or both may extend the spine.
Draws down the last rib, giving fixed point for the diaphragm,
and aids inspiration (Quain); muscle of forced expiration
(Henle). Fixed above, draws pelvis to one side, or both draw
it forward.

2. M. Ilwopsoas.—It has a broad outer head, iliacis, and
a narrow inner head, psoas magnus.

Iliacus.—Origin, upper half of the iliac fossa down as far
as the anterior inferior spine, posteriorly from ala of the sacro-
iliac and iliolumbar ligaments. Inserted mostly into tendon
of the psoas; outermost fibers pass to the femur in front of
and below the small trochanter.

Psoas Magnus (or Major).—Origin, by five fleshy slips from
anterior surfaces and lower borders of the lumbar transverse
process, and by a series of processes, each from a disk and
contiguous margins of two bodies; the highest is attached
to the last dorsal and first lumbar, and lowest to’ the fourth
and fifth lumbar and intervertebral substance between them;
fibers also come from the sacroiliac joint and sacrum. These
attachments are connected with arches passing over the middle
of the vertebrae. The fibers all unite to a thick, long muscle

THE GLUTEAL REGION 221

running along the brim of the pelvis, passing under Poupart’s
ligament, and inserted by a tendon into the small trochanter;
separated by a bursa.

The common tendon is also separated from the capsule
of the hip by a bursa.

3. M. Psoas Parvus (or Minor).—Placed on the surface
of the psoas magnus; rises from the bodies of the last dorsal
and first lumbar vertebrae and disk between; ends in a flat
tendon merged into the iliac fascia and inserted into the ilio-
pectineal line and eminence. When present its origin is variable;
was absent on both sides in 40 per cent. of cases.

THE GLUTEAL REGION

M. Gluteus Maximus.—A quadrilateral, very coarse muscle.
Origin, posterior fourth of the external lip of the iliac crest and
rough surface between it and the posterior gluteal line, back of
the last two pieces of the sacrum and first three of the coccyx,
great sacrosciatic ligament, and aponeurosis of the erector
spine.

The upper half and superficial fibers of the lower half are
inserted into the fascia lata and continued into the iliotibial
-band; the deeper portion of the lower half into the gluteal
ridge on the upper third of the shaft of the femur.

Between this and the great trochanter are a multilocular
bursa and one or two small ones, another between it and the
vastus externus; may be another between it and the tuber
ischii.

M. Gluteus Medius.—Origin, ilium between the crest, the
posterior, and middle curved lines, and from the fascia cover-
ing it, and from a band attached to the anterior posterior
spine; fibers converge to an oblique impression going downward
and forward to insert on the outer surface of the great trochanter;
a small bursa between the bone and tendon. There may be
a separate tendon to the upper part of the trochanter.

M. gluteus minimus is covered by the preceding, and arises
from the whole surface on the ilium between the middle and
inferior curved lines, and by a second head from the anterior
superior spine; fibers converge into an aponeurotic tendon
the outside of the muscle, inserted into an impression on the

222 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

front of the great trochanter. ‘Tendon is bound down by a
band of capsule of the joint from the iliofemoral ligament;
bursa between tendon and tubercle.

M. Pyriformis——Origin, in pelvis by three digitations
from the second, third, and fourth pieces of the sacrum, be-
tween and outside the anterior sacral foramina, from the
hinder border of the ilium below the posterior inferior spine,
and from the great sacrosciatic ligament. Emerges from the
pelvis by the great sacrosciatic foramen; inserted into the
upper border of the great trochanter.

May be divided by the external popliteal nerve (high divi-
sion of the sciatic); inserted into a capsule or absent. May
be a bursa under its insertion.

M. Obturator Internus.—Origin, deep surface of the
obturator membrane, except below; from the fibrous arch,
completing the canal for the obturator vessels and nerve;
from the hip bone between the thyroid foramen and sacroiliac
notch up to the iliopectineal line, and internally between the
foramen and subpubic arch; from the obturator fascia. Emerges
by the small sacrosciatic foramen, changes its direction, and
passes around the trochlear surface of the ischium; inserted
with the gemelli into the forepart of the inner surface of the
great trochanter. It shows four or five tendinous bands on
the surface turned toward the bone, which receive pinnate
fibers. A layer of cartilage covers the grooves on the ischium
and a large synovial bursa. Another may be between the
capsule and tendon. Henle describes the gemelli (gemini)
as parts of this muscle, calling them its outer head.

The gemellus superior, usually the smaller. Origin, outer
and lower part of the ischial spine. Gemellus infertor.—Origin,
upper part of the tuber ischii below the obturator internus;
inserted with obturator internus into the great trochanter.
They usually meet at origin beneath the obturator; they over-
lap it at the insertion. The superior gemellus may be absent
or very small; inferior gemellus is more constant.

M. Quadratus Femoris—Origin, outer border of the
tuber ischii, and from the adjacent part of the external surface
of the tuberosity; insertion, its fibers pass horizontally out-
ward into the quadrate tubercle and back of the femur to
the level of the small trochanter. Bursa between it and the

THE GLUTEAL REGION 223

small trochanter; it may be absent or replaced by the gemellus
inferior. .

M. Obturator Externus.—Origin, inner half of the superficial
surface of the obturator membrane, body of the pubis, rami
of the pubis and ischium; passes out in a groove between the
acetabulum and tuber ischii, then up and backward, close
to the lower and posterior surface of the neck of the femur to
the bottom of the digital fossa. Sometimes bursa is between
it and capsule.

Nerves.—lIliopsoas by the second and third lumbar; those
for the iliacus are given off by the anterior crural; gluteus
maximus by the inferior gluteal nerve; gluteus medius and
minimus by the superior gluteal nerve; obturator internus
gemelli, pyriformis, and quadratus femoris by the sacral plexus;
obturator externus by the obturator nerve.

_ Actions of the glutei on the lower limb:

Flexion. Extension.
Glut. med., anterior fibers. Glut. maximus.
Glut. min., anterior fibers. Glut. med., posterior fibers.

Glut. min., posterior fibers.

Adduction. Abduction.
Glut. med., anterior fibers (in Glut., max., slight.
sitting posture). _ strong, whole
Glut. min., anterior fibers Glut. med., muscle, espe-
(in sitting posture). Glut. min., cially mid-
portion.
Rotate in. Rotate out.
Glut. med., anterior fibers. Glut. max.
Glut. min., anterior fibers. Glut. med., posterior fibers.

Glut. min., posterior fibers. .

The gluteus maximus extends the trunk on the thigh as in
ascending stairs; in walking it is not used, as the erect position
is maintained by ligaments; steadies and supports the knee
by the iliotibial band. |

The iliopsoas flexes the thigh and rotates out; flexes the

224 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

body on the thigh; the psoas bends the lumbar spine forward
and laterally.

Psoas parvus makes tense the iliac fascia.

Pyriformis, obturator internus, and gemelli are external
rotators after extension, abductors if the thigh is flexed.

Quadratus femoris is an external rotator, and may assist
adduction.

Obturator externus is an external rotator; may. flex and adduct.

THE THIGH MUSCLES

These are arranged in three sets—anterior, posterior, and
internal—with superficial and deep layers, the former passing
over two joints, the latter over one.

The Anterior Femoral Region

1. M. tensor vagine femoris (tensor fasciz) lies in a groove
between the gluteus medius, rectus, and sartorius. Origin,
anterior part of the external lip of the iliac crest, notch between
the two spines, fascia over the gluteus medius; insertion, be-
tween the two layers of the fascia lata 3 or 4 inches below the
great trochanter, and from the insertion fibers are prolonged
into the iliotibial band; the outer of the two laminz covers
the muscle; the deeper is connected with the origin of the
rectus.

2. M. Sartorius (tailor muscle).—Origin, anterior superior
spine of the ilium and small part of the notch immediately
below; insertion, inner surface of the tibia near the tubercle,
sending an expansion from the upper border to the capsule,
one from the lower border to the fascia of the leg, and one to
the tibia behind the tendons of the gracilis and semitendinosus.
It is oblique at first, then vertical to the knee, and then curves
forward.

M. Quadriceps Femoris, p. n.—Largest muscle of the body,
four parts closely united. (a) Rectus femoris, inva straight
line from the pelvis to the patella. Origin, by two heads;
anterior one from the anterior inferior spine, and posterior
from the impression just above the acetabulum; they join
at an angle of 60 degrees close below the acetabulum; the

THE ANTERIOR FEMORAL REGION 995

tendon is anterior above, then in centre of the muscle. From
this are pinnate fibers ending in an inferior tendon covering
the lower two-thirds of the posterior surface of the belly, and
leaving a median cleft in the muscle. The lower tendon becomes
free 3 inches above the patella; is attached to the upper margin
of that bone, and helps form the common tendon.

(b) The vastus externus (vastus lateralis, p. n.) is the outer
part of the quadriceps. Origin, narrow and aponeurotic from

the upper half of the anterior intertrochanteric line, outer

part of the root of the great trochanter, outer side of the gluteal
ridge, upper half of the outer lip of the linea aspera, from
external intermuscular septum, and a strong aponeurosis
extending over the upper two-thirds of the muscle. It rises
in a succession of layers, the upper overlapping the lower.
Aponeurosis of insertion occupies the deep surface of the muscle,
joins the common tendon, and sends expansion to the lateral
patellar ligaments and rectus tendon. :

(cand d) Vastus internus (vastus medialis, p. n.) and crureus
(femoralis, p. n.) seem to form one mass, but turn the rectus
tendon well down, and above the patella is an interval which
can be followed up between the two tendons on a line with
the lower end of the anterior intertrochanteric line.

The vastus internus rises from a superficial aponeurosis
and deeper fibers from the spiral line, inner lip of the linea
aspera, and from tendons of the adductor longus and magnus;
they end in a deep aponeurosis which enters the common
tendon. Its muscular fibers pass lower than those of the exter-
nus, and are inserted into the inner margin of the patella,
some into the rectus tendon.

Crureus, rises from upper two-thirds of the anterior surface
of the femur, outer surface of the femur in front of and below
the vastus externus, lower half of the external intermuscular
septum; fibers end in a superficial aponeurosis which forms
the deepest portion of the common tendon. They rise from
a series of transverse arches with intervening bare spaces on
the front of the femur. Between the crureus and the vastus
internus most of the internal surface of the bone is free.

The common or suprapatellar tendon is inserted into the
forepart of the upper border of the patella, and a few fibers
are prolonged over its anterior surface into the ligamentum
patellee.

15

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226 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

M. subcrureus (articularis genu, p. n.) is the name of a few
fibers which may be regarded as the deepest layer of the crureus.
Origin, anterior surface of the femur in the lower fourth;
insertion, separated by a fat layer from the vasti into the
synovial membrane of the knee-joint.

These muscles may be bilaminar.

Hunter’s canal is a three-cornered passage in the middle
two-fourths of the thigh, in the angle between the adductors
magnus and longus and vastus internus. It is made a canal
by a bridge of fascia, and contains the femoral artery, vein,
and internal saphenous nerve.

Nerves.—Anterior crural for the quadriceps and sartorius;
superior gluteal for the tensor vaginze femoris.

Actions.— Sartorius flexes the hip and knee with eversion
of the thigh; rotates the leg inward.

Quadriceps femoris extends the leg; not necessary for the
maintenance of the erect attitude.

Rectus femoris also flexes the hip; its posterior head is tense
when the thigh is bent. Lower fibers of the vastus internus
draw the patella in.

Tensor vagine femoris rotates in and abducts, assisted by
the gluteus maximus; counteracts the gluteus maximus, which
tends to draw the iliotibial band backward.

The Posterior Femoral Region (Hamstrings)

1. M. Biceps Femoris.—Origin, long head by a tendon
common to it and semitendinosus from inner impression on
the lower part of the ischial tuberosity, and from the sacro-
sciatic ligament; short head from the middle third of the outer
lip of the linea aspera and external intermuscular septum;
fibers from both heads end in a tendon inserted into the upper
and outer part of the head of the fibula by two portions em-
bracing the external lateral ligament; some fibers pass forward
and inward to the external tuberosity of the tibia and to the
fascia of the leg.

2. M. Semitendinosus.—Rises from the tuberosity of the
ischium and tendon common to it and biceps for 3 inches.
Terminates in the lower third of the thigh in a long, slender
tendon, and curves forward in an expanded form to insert
on the upper part of the inner surface of the tibia or anterior

Si whine Gs

ae

Muscles in the dorsum of the right thigh.
(Testut.)

Adductores magnus and brevis of the right
side. (‘Testut.)

228 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

crest of the tibia, and sends a process to the fascia of the leg.
It is below the gracilis tendon, covered by the sartorius, and
a bursa separates the three from the internal lateral ligament.
It has a thin, oblique intersection in the middle of its belly.

3. M. Semimembranosus.—Origin, tuber ischii above and
outside the tendon of the biceps and semitendinosus, and
its tendon is grooved posteriorly for the common tendon of
those two muscles. Tendon of origin is on the outer side of
the muscle for three-fourths the length of the thigh; tendon
of insertion, on the opposite side of the muscle, and turns
forward and is inserted by four parts (1) into horizontal groove
on the back of the inner tuberosity of the tibia; (2) expansion
is sent up and in as the posterior oblique ligament of the knee-
joint; (8) down to the fascia over the popliteus muscle; (4)
to form the short internal lateral ligament of the knee-joint.

The hamstring muscles descend mostly in contact with
each other and are bound down by the fascia lata; inferiorly
they diverge the biceps to the outer side, semimembranosus
and semitendinosus to the inner side, forming the upper borders
of the popliteal space, the inferior margins of which are formed
by the heads of the gastrocnemius.

V arieties.—Great reduction in size of the semimembranosus
or absence.

Nerves.—Great sciatic, from its internal popliteal division,
except that to the short head of the biceps, which is from the
external popliteal division.

Actions.—F lex the knee, and then can rotate the tibia and
drag it back under the femur; biceps outward, other two
inward. Powerful extensors of the hip, and limit flexion of
that joint when knee is extended.

The Internal Femoral Region ©

1. M. Pectineus—Origin, iliopectineal line from the ilio-
pectineal eminence and spine of the pubis, and slightly from
bone in front of this, and from the fascia over the muscle;
insertion, femur behind the small trochanter and upper part
of the line passing from this trochanter to the linea aspera.
At origin surfaces are frontal, at insertion are sagittal.

2. M. Adductor Longus (adductor femoris longus).—Flat
and triangular, internal to the pectineus, on same plane.

THE INTERNAL FEMORAL REGION 229

Origin, short tendon from the body of the pubis below the crest
and near the angle; insertion, inner lip of the linea aspera,
united to the vastus internus in front and adductor magnus
behind. :

3. M. Gracilis, or adductor gracilis.—Origin, inner margin
of pubic bone and whole length of its inferior ramus, thin
and flat, then narrow and thicker. A round tendon in the
lower third of the thigh, curving forward below, inserted into
the inner side of the tibia just above the semitendinosus, and
covered by the sartorius. .

M. Adductor Brevis.—Origin, body and inferior ramus of
the pubis below the adductor longus, between the gracilis
and obturator externus; insertion, into the whole line from the
small trochanter to the linea aspera behind the pectineus.
It lies between the adductor magnus and longus.

1. M. Adductor Femoris Minimus.—This is what is described
with the adductor magnus, usually as its anterior and superior
portion. Origin, body of the pubis and ischiopubic rami;
insertion, femur, in a line from the quadratus femoris to the
upper end of the linea aspera, and a short distance along it.

2. M. Adductor Magnus—Origin, ischial ramus internal
to the above muscle and outer half of the triangular space
on the posteroinferior surface of the tuber ischii; fibers pass
in two layers, one to the inner lip of the linea aspera, and the
line extending from the great trochanter to the linea aspera, and
the other on the inner side of the opening for the femoral vessels
by a distinet rounded tendon to insert on the adductor tubercle
on the inner condyle of the femur. The femoral attachment
is interrupted by three or four tendinous arches for the per-
forating arteries.

Adductor longus may extend to knee, inseparable from the
adductor magnus.

Adductor brevis may consist of two or three parts.

Adductor magnus, condylar part may be distinct; usual in
apes.

Nerves.—Adductors by the obturator nerve, but adductor
magnus also by the great sciatic; pectineus regularly by a
branch from the anterior crural, an offset from the obturator
and accessory obturator nerve, only occasionally present.

Actions.—All adduct the thigh. Pectineus, adductor longus
and brevis flex the hip, while part of adductor magnus from

pen ee

230 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

the ischial tuberosity to the condyle may extend the thigh
and rotate in. Giracilis flexes the knee and rotates the leg
inward, Adductors and opponens, the gluteals, balance the
body in walking.

(1) Anterior fibers of the gluteal medius (2) and minimus;
(3) tensor vagine femoris; and some say (4) the condylar
part of the adductor magnus, rotate the thigh inward.

THE MUSCLES AND FASCIA OF THE LEG

There are three groups, as in the forearm; the extensors
are on the anterior side and the flexors on the posterior. The
number of muscles passing over two joints is less in the leg;
no muscle on the anterior and fibular side springs from a point
above the knee.

Fasciz.—The aponeurosis of the leg is not continued over
the subcutaneous surface of the bones, but immediately blends
with the periosteum. It is dense at the upper and front part.
Posteriorly it is continuous with fascia lata, and receives
accessions from the biceps, sartorius, gracilis, and semitendi-
nosus and membranosus tendons. Over the popliteal space
are transverse fibers. It gives off intermuscular septa. In
front of and on the sides of the ankle the aponeurosis is
strengthened by strong bands, forming the annular ligaments.

The anterior annular ligament i is composed of an upper and
a lower band. The upper band, ligamentum annulare, p. n.,
is transverse between the anterior borders of the fibula and
tibia. The tibialis anticus tendon alone has a synovial sheath
under it. The lower band, ligamentum cruciatum, p. n., re-
sembles the letter Y placed on its side, one arm being external
and two internal. The outer portion springs from the hollow
of the os calcis, forming a strong loop, “fundiform ligament
of Retzius,” surrounding the peroneus tertius and extensor
longus digitorum. The horizontal and most constant internal
band passes to the internal malleolus over the extensor proprius
hallucis; and practically beneath the tibialis anticus tendon;
the lower band (oblique) crosses both these tendons, and

becomes continuous with the plantar fascia on the inner side —

of the sole.
There are three synovial sheaths in all—a common one

THE ANTERIOR TIBIOFIBULAR REGION 231

for the peroneus tertius and extensor longus, one for the extensor
proprius hallucis, and one for the tibialis anticus; may be a
bursa between the fundiform ligament and neck of the
astragalus.

- Internal annular ligament (ligamentum laciniatum, p. n.)
covers the flexor tendons, completing canals; it is attached
to the inner malleolus and posteriorly to the inner side of the
os calcis.

The external annular ligament (retinaculum peroneorum
superius, p. n.) forms sheaths for the long and short peroneal
tendons, passing from the outer malleolus to the os calcis.
May be subcutaneous burs over the malleoli and over the
lower end of the tendo Achillis.

The Anterior Tibiofibular Region (Extensors) ©

1. M. Tibialis Anticus (“chain-muscle’’).—Origin, external
tuberosity of the tibia, upper half of the outer surface of that
bone, and adjacent interosseous membrane, fascia of the leg,
and intermuscular septum; insertion, oval mark on the inner
and lower part of the internal cuneiform and first metatarsal,
dividing into two slips. A small bursa may be under its near
insertion. |

A part may be inserted into the astragalus, also a slip may
go to the head of the first metatarsal or base of first phalanx.

2. M. Extensor Longus or Proprius Hallucis.—Origin, middle
two-fourths of the narrow anterior surface of the fibula and
contiguous portion of the interosseous membrane; insertion,
base of the terminal phalanx of the great toe on ‘the dorsal
aspect. It spreads in an expansion on each side over the meta-
tarsophalangeal articulation, and almost always sends a slip
to the base of the proximal phalanx.

3. M. Extensor Longus Digitorum Pedis.—Origin, external
tuberosity of the tibia, head and upper two-thirds of the
anterior surface of the fibula, very largely from the septa
and fascia and interosseous membrane above the origin of
the extensor proprius hallucis. Tendon divides into four slips
for the outer four toes. They are continued into expansions
which are joined on the proximal phalanx by processes from
the interossei and lumbricales. They divide into three parts—
the middle inserted into the middle phalanx; the lateral parts

252 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

unite, and are inserted into the base of the terminal phalanx,
as in the case of the extensors of the fingers.

Tendons to the second and fifth toes may be doubled; extra
slips from one or more tendons to the metatarsal bones, to
short extensor, or to interossei; a slip to the great toe. Slip
for the little toe may be separable to origin.

4. M. Peroneus Tertius.—Origin (below the extensor longus
digitorum, and united -with it), lower third or more of the
anterior surface of the fibula, from the interosseous membrane,
from the septum between it and the peroneus brevis; insertion,
upper surface of the base of the fifth metatarsal, sometimes
the fourth. This muscle is peculiar to man.

Nerves.—All by the anterior tibial nerve.

The Fibular or Peroneal Region

1. M. Peroneus Longus.—Origin, few fibers from the outer
tuberosity of the tibia, head and upper two-thirds of the
external surface of the fibula, fascia of the leg, and septa on
each side. It has an anterior and a posterior head with pero-
neal nerve between. ‘Tendon begins in the lower half of the
leg, passes behind the external malleolus; then forward on the
outer side of the os calcis, winds around the tuberosity of the
cuboid, and enters its groove, crosses the sole obliquely, and
is inserted into the outer side of the tuberosity of the first
metatarsal, and slightly into the internal cuneiform; a frequent
offset to the base of the second metatarsal and first dorsal
interosseous.

Both peroneal tendons are in the same sheath under the
annular ligament, but on the os calcis each has its own sheath,
separated by the peroneal spine, when it exists, and a fibrous
septum. A single synovial sac sends two processes down into
the special sheaths.

A second synovial membrane is in the cuboid groove. A
sesamoid fibrocartilage or bone is on the tendon, playing over
the cuboid tuberosity. The special fascia binding down the
peroneal tendons is the retinaculum peronworum inferius, p. Nn.

2. M. Peroneus Brevs.—It lies deeper than the peroneus
longus. Origin, lower two-thirds of the external surface of
the fibula from the septa and a flat tendon on the surface
turned toward the bone; insertion, tuberosity at the base of

THE POSTERIOR TIBIOFIBULAR REGION 233

the fifth metatarsal, sending a small slip to the outer edge
of the extensor of the little toe or forepart of the metatarsal
bone.

Nerves.—Musculocutaneous branch of the external popliteal
or peroneal nerve.

The Posterior Tibiofibular Region (Flexors)

Superficial Muscles—1. Mm. Gastrocnemius and Soleus (m.
triceps sure).—Gastroecnemius has two large heads from the
femur, terminating at the middle of the leg in a common tendon.
Outer head from the depression on the outer side of the external
condyle above the tuberosity, and from the posterior surface
of the femur just above that condyle. Inner head from the
upper part of the internal condyle behind the adductor tubercle,
and lower end of the supracondylar ridge. The two heads
enlarge, and soon meet, do not join, separated superficially
by a groove and deeply by a thin band.

The inferior tendon is broad and aponeurotic, and on the
deep surface.

The lower edge of each muscular part is convex downward;
the inner head is the broader and thicker, and descends the
lower in its insertion into the common tendon. A bursa is
between it and the semimembranosus, and another between
it and the femur.

Outer head may develop a sesamoid fibrocartilage or bone
over the condyle of the femur.

Soleus.—Origin, externally from the posterior surface of
the head and upper third of the shaft of the fibula; internally,
oblique line and inner border of the tibia to its middle, and
from a tendinous arch over the popliteal vessels and nerve;
fibers rise to a large extent from two tendinous laminze which
descend in the muscle, one from the fibula and one from the
tibia. Fibers from the anterior surfaces of these laminze con-
verge to a median septum; fibers from their posterior surfaces
pass down and back to an aponeurosis covering the back surface
of the muscle. The tendon of insertion is prolonged from this
aponeurosis, joined by the median septum. Muscular fibers
are continued down on the deep surface of the tendo Achillis
near to the heel. The tibial head is almost peculiar to man.

_ > te!

234 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM |

Tendo Achillis, broad at first, contracts to within 15 inches
of the heel, then expands, and is inserted into the middle and
lower parts of the posterior surface of the tuberosity of the
os calcis, a bursa having all the characters of a synovial mem-
brane, with vascular and fatty synovial tufts, separating it
from the upper part of this surface. . |

2. M. Plantaris.—Origin, femur above the external condyle
and from the posterior ligament of the knee-joint. Muscular
belly 3 to 4 inches long, and the long, slender tendon turns
in between the gastrocnemius and soleus to the inner border
of the tendo Achillis, and inserted by its side into the caleaneum

May join tendo Achillis, end in fascia of the leg or internal
annular ligament, or be enclosed in the tendo Achillis. Absent
in 7.5 per cent. It is the remains of a superficial flexor of the
digits, like the palmaris longus.

3. M. Popliteus.—Origin, round tendon, 1 inch long, from
the groove on the outer surface of the external condyle of
the femur, within the capsule of the joint, in contact with the
semilunar cartilage, and by muscular fibers from the ligamen-
tum popliteus arcuatum. Fibers pass down and are inserted
into the triangular surface of the tibia above the oblique line,
and into the aponeurosis over the muscle. ‘The tendon is
in the groove on the femur only in full flexion. Henle gives
origin below and insertion above. |

The Deep Muscles (Flexors)

1. M. Flexor Longus Digitorum Pedis (Perforans).—Origin,
inner portion of the posterior surface of the tibia for the middle
two-fourths of its length, from the aponeurosis over the tibialis
posticus. Descends behind the internal malleolus, passes
forward and obliquely outward, having crossed the tibialis
posticus tendon in the leg, and now crossing that of the flexor
longus hallucis, in each case superficially. It divides into four
parts for terminal phalanges of the four lesser toes. The whole
arrangement of the vincula accessoria, etc., is as for the fingers.

2. M. Tibialis Posticus, beneath the two long flexors.
Origin, posterior surface of the interosseous membrane, outer
part of the posterior surface of the tibia below the oblique
line to the middle of the bone, whole inner surface of the fibula,
and from the aponeurosis over it. Tendon along the inner

ee | alles i AT
7 nate

MUSCLES AND FASCIZ OF THE FOOT 239

border of the muscle, free at the level of the lower tibiofibular
articulation, passes behind the inner malleolus; inserted into
the tuberosity of the scaphoid, with offsets to the three cunei-
form, to cuboid, to bases of the second, third, and fourth
metatarsals, and to the transverse tarsal ligament and flexor
longus hallucis tendon, and sends a thin process back to the
sustentaculum tali.

3. M. Flexor Longus Hallucis—Origin, lower two-thirds
of the posterior surface of the fibula, septum between it and
the peronei;.aponeurosis common to it and flexor longus digi-
torum. Tendon at the posterior surface of the muscle traverses
groove on the back of the astragalus and under surface of the
sustentaculum, gives slip to the flexor longus digitorum in
the sole of the foot, and proceeds to the base of the terminal
phalanx of the great toe.

Nearly always a slip from the flexor hallucis to the flexor
digitorum, and (1 in 5) another from the flexor digitorum to
the flexor hallucis.

Slip from the flexor hallucis passes to the second and third
toes, 52 per cent.; to the second only, 28 per cent.; to the second,
third, and fourth, 19 per cent.; or rarely to all four.

Nerves.—Gastrocnemius, plantaris, and popliteus by the
internal popliteal nerve. Soleus by the internal popliteal
and posterior tibial. Flexor longus digitorum, flexor longus
hallucis, and tibialis posticus by the posterior tibial nerve.

MUSCLES AND FASCIZ OF THE FOOT

Fascia of the dorsum is a thin layer over the extensor ten-
dons, with deeper layers over the short extensors and interossei.

Superficial fascia of the sole forms a thick cushion of fatty
lobules bound down by bands passing vertically from the
skin to deep fascia. Small burse over the heel and first and
fifth metacarpals.

Deep Fascia of the Sole.—Plantar fascia, central and two
lateral portions. The inner is thin and loose, covers the abductor
hallucis, and is continuous with the dorsal fascia and internal
annular ligament. Outer part covers the abductor minimi
digiti, and forms a thick band, especially between the outer
tubercle of the os calcis and tuberosity of the fifth metatarsal,

236 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

continuous with the dorsal fascia, and sends a_ prolongation
forward over the short flexors of the little toe.

Central portion has dense white, glistening fibers, from the
inner tubercle of the os calcis to the roots of the toes; divides
into five processes in front. ‘Thin transverse fibers cover the
lumbricals and digital nerves. Identical arrangement as in
the palmar fascia; fibers to the digital sheaths, superficial
transverse ligament, and:skin, and deep processes to the trans-
verse metatarsal ligament.

Two intermuscular septa are between the middle and lateral
portions, giving partial origin to muscles.

Superficial transverse ligament of the toes is in folds of’ skin
‘at the interdigital clefts, connected to the tendon sheath
beneath. Connects all five digits.

The Dorsal Region ‘

1. M. Extensor Brevis Digitorum Pedis.—Rises from fore-
part and upper and outer surface of the os calcis, in front
of the groove for the peroneus brevis tendon, and from the
anterior ligament of the ankle. The tendon has several vertical
leaflets from which muscular fibers rise, dividing into three
bellies which unite with the outer border of the long extensors
for the second, third, and fourth toes.

2. M. Extensor Brevis Hallucis (often described with the
above).—Origin, two heads—outer from the upper surface
of the os calcis close by the anterior edge, and connected with
the extensor brevis digitorum; inner head from the lower
arm of the annular ligament. Tendon is free at the tarso-
metatarsal joint, passes under the tendon of the extensor
longus hallucis, and is expanded and inserts on the dorsum
of the proximal phalanx.

The Plantar Region

None corresponding to the palmaris brevis; three groups
as in the hand, middle group richer than that of the hand.
Great toe, fewer than the thumb group. Little toe group,
like number and arrangement.

THE PLANTAR REGION AT

The Central Group.—l. M. Flexor Brevis Digitorum (per-
foratus).—Origin, inner tubercle of the os calcis, plantar fascia,
septa, and calcaneocuboid ligaments. Terminates in four
slender tendons inserted into the sides of the mesial phalanges
of the four outer toes; each divides and gives passage to the
long flexor, as does the flexor sublimis of the hand.

2. Flexor Accessorius (m. quadratus plante, p. n.).—Henle
ealls it the “plantar head of the flexor longus digitorum.”’
Flat quadrilateral muscle. Origin, two heads—internal and
larger from the inner surface of the os calcis; external, narrow
and tendinous, from the under surface of the os calcis just
in front of the outer tuberosity and from the long plantar
ligament; insertion, external border and upper surface of the
flexor longus digitorum tendon.

3. Mm. Lumbricales—Four in number. Origin, at points
of division of the flexor longus digitorum tendon, each attached
to two tendons, except the most internal one; they pass to
the inner side of the four outer toes; inserted into the bases
of the proximal phalanges (Henle).

The Internal Group.—1. M. Abductor Hallucis.—Origin, inner
tubercle of the os calcis, internal annular ligament, septum,
plantar fascia; insertion, inner border of the base of the proximal
phalanx of the great toe, inner sesamoid bone, and tendon of
the extensor longus hallucis. Slip to the proximal phalanx
of the second toe. May have a second head from the scaphoid.

2. M. Flexor Brevis Hallucis.—Origin, flat process from the
cuboid inner border, from the slip of the tibialis posticus tendon
to the two outer cuneiform bones, from the sheath of the flexor
longus digitorum; inserted by two heads into the inner and
outer borders of the base of the proximal phalanx, in connec-
tion with the abductor hallucis and adductors. Sesamoid
bone in each head.

Origin from the os calcis or long plantar ligament. Sends
slip to the second toe, first phalanx. Inner head regarded by
some as belonging to the abductor.

3. M. adductor hallucis has two heads, as in hand, an oblique
and transverse, only more separated.

Caput Obliquum, p. n.—Origin, tarsal extremities of the
third and fourth metatarsals, sheath of the peroneus longus,
caleaneocuboid ligament, and third cuneiform; insertion,

238 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

outer side of the base of the first phalanx of the great toe,
somewhat above the tendon of the peroneus longus.

Caput transversum (transversus pedis) is covered by flexor
tendons. Origin, inferior tarsometatarsal ligaments of the
three outer toes and transverse metatarsal ligaments; inserted
with the oblique head and flexor brevis into the first phalanx
of the great toe and extensor tendon. —

The External Group.—1l. M. Abductor Minima Digiti.—Origin,
both tubercles of the os calcis, external septum, band of the
plantar fascia between the external tubercle and base of the
fifth metatarsal; inserted into the base of the fifth metatarsal
and outer side of the base of the first phalanx of the little
toe. The tendon usually receives muscle fibers from the base
of the fifth metatarsal.

2. M. Flexor Brevis Minimi Digiti.—Origin, base of the fifth
metatarsal, and calcaneocuboid ligament, sheath of the peroneus
longus; insertion, base and external border of the first phalanx
of the little toe; deeper fibers generally end on the anterior half
of the fifth metatarsal.

The Interossei Muscles

Mm. interossei, as in the hand, are seven in number, four
dorsal and three plantar. The dorsal project downward as
low as the plantar, and alternate with them.

Each dorsal interosseous has two heads and a central tendon,
which is inserted partly into the base of the proximal phalanx
and into the aponeurosis of the corresponding slip of the
common extensor tendon. The first two are inserted, one on
either side of the second toe, the third and fourth into the
outer sides of the third and fourth. Inner head of the first is
small, and rises from the first metatarsal and internal cunei-
form; the third and fourth receive fibers from the sheath of
the peroneus longus.

Plantar interossei, rise from the inner and under surface
of the third, fourth, and fifth metatarsals, one-headed, and
from the sheath of the peroneus longus. Inserted into the
inner side of the proximal phalanges of the third, fourth, and
fifth toes, and into the aponeurosis of the corresponding slip of
the common extensor tendon,

ee
e _ caer
>

THE INTEROSSEOUS MUSCLES 239

Nerves.—Extensor brevis by the anterior tibial. Flexor
brevis digitorum, abductor and flexor brevis hallucis, and
innermost lumbricalis by the internal plantar; all the others
by the external plantar.

Actions.—Popliteus flexes the knee and rotates the leg in,
pulls on the capsule of the joint, and keeps the popliteal bursa
open. The dorsum of the foot and anterior surface of the leg
is the extensor surface; the opposite side is the flexor surface,
so that raising the foot on the front of the leg is really extension,
and depressing it is flexion; it is customary to apply reverse
terms to these acts.

Gastrocnemius flexes the knee, extends the ankle, combines
with the soleus and lifts the heel or raises the body on toes.

Tibialis anticus and peroneus tertius flex the ankle; the
former rotates in, adducts, raises the first metatarsal bone.

Tihialis posticus, peroneus longus and brevis are extensors.
Tibialis posticus and flexors of the toes rotate the foot in.
The three peronei and extensors of the toes rotate out.

Peroneus longus strengthens the transverse arch, lifts the
outer border of the foot in walking, extends the foot, depresses
the first metatarsal, abducts the forefoot, rotates out.

Flexors and extensors of the toes, interossei, and lumbricales
act as do the corresponding muscles of the hand.

Flexor accessorius modifies the action of the flexor longus
digitorum, as those tendons cannot enter the foot in a straight
line.

The extensor brevis digitorum does the same for the extensor
communis, though here they are not so much needed, and their
function is not so evident.

Extensors of the foot slightly rotate in; flexors of the foot
slightly rotate out; plantaris indirectly pulls up the capsule
of the ankle-joint and slightly aids the gastrocnemius.

Flexors of the Foot. Extensors of the Foot.
Tibialis anticus. Tendo Achillis.
Extensor communis digitorum. Peroneus longus and brevis.
Extensor proprius hallucis. Tibialis posticus.
Peroneus tertius. Flexor longus digitorum and

hallucis,

ee

240 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM

Adduction. Abduction.
Tibialis posticus (strongly). Peroneus brevis.
Tendo Achillis (weakly). Peroneus longus.

Perhaps tendons behind the inner
malleolus, perhaps the tibialis

anticus.
Rotation in. ° Rotation out.
Tibialis anticus (strongly). Peroneus longus.
Tendo Achillis. Extensor communis digitorum.

Peroneus tertius.

Nore.—The following are included under Muscles of Thorax,
page 198. é

Levatores costarum muscles are twelve in number, one on
each side. They arise by small tendinous and fleshy -bundles
from the extremities of the transverse processes of the seventh
cervical and the eleven upper thoracic vertebrae. Pass obliquely
downward and outward to be inserted into the upper border,
between the tubercle and the angle, of the rib, adjacent to its
vertebre of origin, below. Each of the inferior levatores divides
into two fasciculi, one of which is inserted as above described;
the other fasciculus passes to the second rib below its origin;
thus each of the lower ribs receives fibers from two vertebre.

QUESTIONS ON .THE MUSCLES AND FASCLE

THE MUSCLES AND FASCLE OF THE NECK

What structure lies on the Scalenus anticus?
Give the nerve supply of the Sternomastoid.—
What muscles form the boundaries of the triangles of the neck?

THE MUSCLES AND FASCIA OF THE TRUNK

From what vertebrz does the Latissimus dorsi arise?

Give the nerve supply of the Trapezius.

What muscles form the boundaries of the suboccipital triangle?

Describe the arrangement of the aponeuroses of the Internal
abdominal oblique and Transversalis with reference to the Rectus
abdominalis,

What forms Poupart’s ligament? Gimbernat’s ligament?

Describe the inguinal canal.

ee do the fibres of the clavicular portion of the Pectoralis major
insert

where do the fibres of the lowest part of the Pectoralis major
insert?
’ What is the relation of the Pectoralis major tendon to the biceps?

THE MUSCLES AND FASCL# OF THE UPPER
EXTREMITY

Take each muscle of the upper extremity, state its shape and loca-
tion, and minutely its origin, its insertion, the direction of its fibres, its
innervation, and its relation to important structures.

What structure passes through the Coracobrachialis?

What connection is there between the glenoid head of the Biceps
and the glenoid ligament?

Which of the Teres muscles is behind the tendon of the scapular
head of the Triceps?

What nerve supplies the Teres minor?

What limits the Supinator longus above?

What separates the origins of the internal and external heads of
the Triceps?

What passes between the heads of the Pronator radii teres?

From how many bones does the Flexor sublimis digitorum arise?

From how many bones does the Flexor profundus digitorum arise?

What structures pass between the heads of the Flexor carpi ulnaris?

What passes between the planes of the Supinator brevis?

Which tendons are the more superficial where they cross, those of
the short extensors of the thumb or those of the Extensores carpi
radialis longior and brevior?

What arises just below the Extensor longus pollicis?

To which side of the common extensor tendon to the index finger is
the tendon of the Extensor indicis?

Has the Extensor minimi digiti one or two tendons?

oY a a

Beginning with the Supinator longus in the upper third of the fore-
arm, name in order the muscles found in passing completely around .
the forearm.

What is the nerve supply of the Flexor digitorum profundis?

What is the nerve supply of the Flexor brevis pollicis?

THE MUSCLES AND FASCIZ OF THE LOWER ~—
EXTREMITY

Take each muscle separately, state its shape and location, and give
precisely its origin, insertion, direction of fibres, innervation, and
relation to important structures. ;

What is the nerve supply of the Pectineus, the Tensor vaginz femoris,
and Adductor magnus?

A ney is the relation of the Obdurator externus to the neck of the
emur

What angle does the part of the Obturator internus within the
pelvis make with the part without the pelvis?

What relation does the Semimembranosus bear to the Biceps and
Semitendinosus just below the tuber ischii?

Draw the linea aspera with its upper and lower extensions, marking
the muscular attachments.

What is the order of the deep layer of the posterior leg muscles
from within outward, and what is the relation of their tendons behind
the internal malleolus?

Which of the Peronei muscles is superficial, then posterior, and then
inferior to the corresponding portion of the other?

Describe the femoral canal.

-

:
:

bn

Z I

Pe PART IV

THE VASCULAR SYSTEMS

THE PERICARDIUM

THE pericardium is a fibroserous membrane which invests the
heart and the great vessels at their origin for about two inches.
Below, it is attached to the diaphragm and its central tendon;
in front it is separated from the sternum by the thymic remains,
some areolar tissue, and overlapped by the margins of the lungs,
especially, of the left; behind it are the esophagus, bronchi, and
descending aorta; laterally it is covered by the pleurz, with the
phrenic nerve and vessels running between the two membranes.

The pericardium consists of a fibrous and a serous layer.
The fibrous layer is attached below to the diaphragm and its
central tendon. Above, it forms a tubular investment for the |
great vessels which is lost on the external coat, and may be
traced above into the pretracheal portion of the deep cervical
fascia, and in front is attached to the posterior surface of the
sternum by the superior and inferior sternopericardial ligaments
(Luschka). The vessels invested are the aorta, superior vena
cava, both pulmonary arteries, and all the pulmonary veins.

The serous iayer invests the heart and is reflected to the
fibrous layer. It also invests the great vessels for about two
inches. The aorta and pulmonary artery are completely in-
vested, thus between them and the auricles posteriorly is the
transverse pericardial sinus. The pulmonary veins and both
the venz cavee are only partially invested.

THE HEART

The heart is a hollow muscular organ, of somewhat conical
form, lying between the lungs and enclosed by the pericardium,
16

249 THE VASCULAR SYSTEMS

It contains four chambers, an auricle and a ventricle on each
side.

It lies obliquely, the base being directed upward, backward,
and toward the right, and extending from the level of the fifth
to that of the eighth dorsal vertebra, and the apex looking
downward, forward, and to the left, its impulse against the
chest wall being felt in the fifth left interspace, about 3% inches
from the middle of the’sternum. The heart lies more in the left
than in the right side of the chest, its base being held in position
by the great vessels which are connected with it; its posterior
or posteroinferior surface is flat, formed chiefly by the left
ventricle, and rests on the diaphragm; and its anterior surface,
formed chiefly by the right ventricle, but also partly by the left,
is convex and covered to some extent by the lungs. Of the
borders, the right is long and thin, and the left is shorter and
thick. The length of the heart is about 5 inches; its greatest
breadth is 33 inches; its thickness is about 25 inches. Its weight
is 10 to 12 ounces in the male, 8 to 10 in the female, and it
increases with age.

Externally it presents a deep transverse groove, the auriculo-
ventricular, which marks off an upper or auricular and a lower
or ventricular portion; this latter part presents a longitudinal
furrow on the front and back, the former being somewhat to
the left, the latter to the right, marking off the right and left
ventricles.

The interior of the heart is divided by a longitudinal septum
into a right and a left part, and these, in turn, are divided into
an auricle and a ventricle.

THE RIGHT AURICLE

The right auricle is larger than the left, its wall being about
one line in thickness and its capacity 2 ounces. Its cavity is
divided into two parts, the sinus venosus and the appendix
auricule, the former lying between the entrances of the two
ven cavee, the latter overlapping the commencement of the
aorta.. Within the auricle the following parts present them-
selves for examination:

1. The orifice of the superior vena cava, looking downward and
forward. ,

THE RIGHT VENTRICLE 243

2. The ortfice of the inferior vena cava, at the lowest part, near
the septum, looking upward and inward.

3. Between the two caval openings a projection, the tuber-
culum Lowert.

4. The opening of the coronary sinus, between the inferior
cava and the auriculoventricular opening, and protected by
the fold of endocardium forming the coronary valve.

5. Numerous small openings (foramina Thebesir) of the ven
cordis minime.

6. The auriculoventricular opening.

7. The Eustachian valve, between the front of the inferior
vena cava and the auriculoventricular orifice. It is semilunar
in form, the free concave margin sending one cornu to join the
front of the annulus ovalis and the other to the auricular wall.

8. The fossa ovalis, at the back of the septum, in the situation
of the fetal foramen ovale, its prominent margin being known
as the annulus ovalis.

9. The museuli pectinati, small elevated columns which trans-
verse the appendix and the adjacent part of the sinus.

The auriculoventricular bundle of His is situated in the median
septum between the auricles and ventricles. It commences
near the opening of the coronary sinus, where the fibers con-
verge, forming a node (node of Tawara), and continues as a
compact bundle which passes forward in the lower part of the
pars membranacea septi to the upper part of the muscle portion
of the ventricular septum, and divides into right and left
fasciculi. Each limb passes to the papillary muscles surrounded
by a layer of connective tissue, embedded within the muscle
of the septum, but in the lower parts of the ventricles each
fasciculus divides into several strands, which pass to the papil-
lary muscles and entire internal surface of the ventricular
surfaces and forms there histological connections with the cells
of the heart muscle fibers (Gray).

THE RIGHT VENTRICLE

The right ventricle is pyramidal, and extends nearly to the
apex of the heart. It is bounded internally by the convex sur-
face of the septum ventriculorum, and prolonged above and
internally into a pouch, the infundibulum, or conus arteriosus,

244 THE VASCULAR SYSTEMS

from which springs the pulmonary artery. Its cavity has a
capacity of three ounces. On opening the ventricle the following
“parts are presented for examination:

1. The auriculoventricular orifice, oval in form and placed
near the right side of the heart. Around its circumference is a
fibrous ring, and it is guarded by the tricuspid valve.

ANNULUS
OVALIS Z

TUBERCLE...
OF LOWER

y

OVALIS~ a
ANNULUS...
OVALIS _RIGHT CORO-

“NARY ARTERY

EUSTACHIAN |
VALVE

VALVE OF _
THEBESIUS

ath ya {TRICUSPID
OPENING OF; VALVE
CORONARY SINUS

Right auricle and part of right ventricle, the front wall having been removed.
(Testut.)

2. The opening of the pulmonary artery, circular in form, at
the summit of the conus arteriosus, near the septum; is guarded
by the pulmonary valve (semilunar).

3. The tricuspid valve consists of three triangular flaps formed
of fibrous tissue covered by endocardium. They are continuous

j | 3 THE LEFT AURICLE 245
r:
b

with one another at their bases, and their free margins and
ventricular surfaces give attachment to the chorde tendinee.
Their central part is thick and strong, the lateral margins
thinner and flexible.

4. The chorde tendinee are attached as follows: several to the
attached margin of each flap, blending with the fibrous ring;
several to the strong central part; and the finest and most
numerous to the margins. of each curtain.

5. The columne carnee are projecting bundles of muscular
substance found all over the ventricular wall excepting the
conus arteriosus. They are of three classes: the first are mere
ridges, attached by one side and both extremities; the second
are attached only by both extremities; the third (musculi
papillares) are two in number, an anterior and a posterior,
attached by only one extremity, the free end having chordee
tendinez attached to it.

6. The three semilunar valves guard the pulmonary orifice.
They are semicircular, their free margins being thick and ten-
dinous and presenting at the middle a small fibrous nodule, the
corpus Arantii. On each side of this body, just behind the free
margin, the valve presents a small thinned-out interval, and
when the valves are closed during diastole these valves (lunule)
are in contact, and so also are the three nodules. These latter
prevent any leakage from the triangular space which would
otherwise be left. |

7. At the commencement of the pulmonary artery are three
pouches, the sinuses of Valsalva, placed one behind each valve.
They resemble those of the aorta, but are smaller.

THE LEFT AURICLE

The left auricle is smaller and thicker walled than the right,
and consists, like the right, of a sinus and an appendix. The
latter overlaps the pulmonary artery. Within it presents the —
following features of interest:

The orifices of the pulmonary veins, opening two into the right
and two into the left side; the auriculoventricular orifice; and
a few musculi pectinati on the inner side of the appendix.

246 THE VASCULAR SYSTEMS

THE LEFT VENTRICLE

The left ventricle is longer than the right, and forms the apex
of the heart. Its walls are three times as thick as those of the
right. Within it presents for examination:

1. The auriculoventricular orifice, which is smaller than the
right and guarded by the mitral or bicuspid valve; and the
aortic opening, in front and to the right of the preceding,
guarded by the semilunar valves.

2. The mitral valve is attached, like the tricuspid, on the right
side. It consists of two curtains which are larger and thicker
than those of the tricuspid, and of two smaller segments, one
at each angle of junction of the former. ‘They are furnished
with chord tendinex. —

3. The aortic semilunar valves are similar to but larger and
stronger than the pulmonary valves.

4. Columne carnee are found as in the right ventricle, and
the musculi papillares are very large; one is attached to the
anterior wall, the other to the posterior.

The Endocardium.—The inner surface of the heart is lined by
a thin membrane, the endocardium, continuous with the inner
lining of the great bloodvessels, and helping to form by its
folds the various valves.

Blood and Nerve Supply.—The heart is supplied with blood by
the coronary arteries, and with nerves by the cardiac plexuses,
formed by branches of .the pneumogastric and sympathetic
nerves.

The muscle fibers of the heart are attached to cartilaginous
rings which surround the auriculoventricular and arterial orifices.

THE ARTERIES

There are two great arterial systems—(1) the pulmonary,
(2) the corporeal.

THE PULMONARY ARTERIAL SYSTEM

The pulmonary artery is a short, wide vessel, 2 inches in length.
Commencing at the base of the right ventricle, it curves upward

THE ARCH OF THE AORTA 247

and backward, to end under the transverse aorta by dividing
into a right and a left branch.

Relations.—J/n front, second left intercostal space and cartilage,
left border of the sternum; behind, origin of the aorta, left
auricle; above, transverse aorta, remains of the ductus arteriosus;
to the right, right appendix and coronary artery, ascending aorta;
to the left, left appendix and coronary artery.

This vessel, with the ascending aorta, is enclosed in a sheath
of pericardium. It winds around the aorta, being at first in
front, and later to the left side, of the ascending portion. In
fetal life the ductus arteriosus connects it a little to the left
of its bifurcation with the transverse aorta.

Each branch enters the root of the corresponding lung; the
right, the larger, passing behind the ascending aorta and
superior vena cava; the left, in front of the descending aorta.
The left divides into two branches for the lobes of the left lung;
the right also divides into two primary branches for the upper
and lower lobes. From the lower one of these is sent a branch
to the middle lobe.

THE CORPOREAL ARTERIAL SYSTEM

The Aorta

The aorta is the main trunk from which spring the systemic
arteries. From the base of the left ventricle it runs upward,
forward, and to the right as far as the second right cartilage;
then backward and to the left, over the root of the left lung,
to the fourth dorsal vertebra; thence, along the spine, it descends
through the thorax and abdomen, to divide, at the fourth lumbar,
into the common iliacs.

It has been divided, for convenience of description, into the
arch and the descending aorta. The arch is subdivided into
the ascending, transverse, and descending parts; the descending
aorta, into the thoracic and abdominal portions.

The Arch of the Aorta

The ascending part of the arch runs upward, forward, and to
the right, from a point opposite the lower border of the third

248 THE VASCULAR SYSTEMS

left cartilage, to the upper border of the second right cartilage.
Close to its origin it presents three small dilatations, the sinuses
of Valsalva, indicating the situation of the semilunar valves.

Relations.—In front, pulmonary artery, right appendix, thoracic
fascia, right pleura, pericardium, remains of the thymus gland;
be hind, root of the right lung, including right pulmonary ves-
sels, left auricle; to the right, right auricle, superior vena cava;
to the left, pulmonary artery.

The transverse part of the arch passes backward and to the
left as far as the left side of the body of the fourth dorsal
vertebra.

Relations.—In front, lungs and pleura, thymic remains, left
vagus, phrenic and superficial cardiac nerves, left superior
intercostal vein; behind, trachea, esophagus, thoracic duct, deep
cardiac plexus, left recurrent nerve; above, left innominate vein
and the branches of this portion of the aorta, viz., innominate,
left carotid, and subclavian arteries; below, left bronchus, bifur-
cation of the pulmonary artery, ductus arteriosus, left recurrent
nerve.

The descending part of the arch descends to the lower border
of the fifth dorsal vertebra, ending in the thoracic aorta.

Relations.—In front, root of the left lung covered by pleura;
behind, left side of the body of the fifth dorsal vertebra; right
side, esophagus, thoracic duct; left side, left lung, covered by
pleura.

The Branches of the Arch of the Aorta

The branches of the arch are five—coronary, right and left,
from the ascending part; and the innominate, left carotid, and
left subclavian, from the transverse part. The descending part
gives off no branches.

The coronary arteries supply the heart and the coats of the
great vessels. They emerge on either side of the pulmonary
artery, between it and the corresponding appendix auricule.
Each arises from a sinus of Valsalva, just above the free margin
of the corresponding semilunar valve, and is distributed to the
muscular substance of the heart, its valves and septa, running
along the grooves on its surfaces, and anastomosing freely with
the other, and, by means of twigs to the aorta and pulmonary
artery, with the pericardiac and bronchial vessels. Each

d
;

THE BRANCHES OF THE ARCH OF THE AORTA 249

Fig. 39°

_\ Thyroid gia DYNE

PRR \ Left vagus.
ight vagus. — Left phrenic.

Recurrent laryngeal.
i Th
Oe i\\\.

Thoracic duct.
»

Plan of the
Branches.

>
Q
2,
&.

Subelaria,,

buypuaosed

Right Coronary
Artery

/
/

| Left Cor
Art

}.10F |

The arch of the aorta and its branches.

250 THE VASCULAR SYSTEMS

divides into two primary branches, the right vessel running in
the posterior and the left in the anterior, interventricular, and
auriculoventricular grooves.

The innominate (brachiocephalic) artery is the largest branch.
It arises in front of the left carotid, and runs obliquely to the
right sternoclavicular joint, where it divides into the right
common carotid and right subclavian.

Fia. 40
Vein azygos major.

Right Sm,
pulmonary veins.) go) <i ie

Right’

\

4 “ord
- 5 - Left common carotid.

Left innominate vein. f

Relation of great vessels at base of heart, seen from above. (From a preparation
in the Museum of the Royal College of Surgeons of England.)

Relations. —Jnfront, manubriumsterni, sternohyoid and thyroid
muscles, thymic remains, left innominate and right inferior
thyroid veins, inferior cervical cardiac nerve from the right
vagus; behind, trachea and pleura; right side, pleura, right
vagus, right phrenic nerve, and the right innominate vein; left
side, remains of the thymus and trachea. The left carotid
artery as it leaves the arch is behind and to the left of this vessel.
The innominate regularly gives off no branches. Occasionally,

THE BRANCHES OF THE ARCH OF THE AORTA 251

however, a thymic or bronchial branch or the arteria thyroidea
ima arises from it.

The common carotid arteries are identical in course, branches,
and relations in the neck, but differ in their origin. Thus, the
right i is a branch of bifurcation of the innominate, while the left
is a primary branch of the transverse aorta. From its origin
the left carotid passes obliquely upward and outward to the
left sternoclavicular joint, and from that point follows a course
corresponding to that of the right carotid. A thoracie portion
of the left carotid artery is therefore described.

Relations.—Jn front, sternum, sternohyoid and _ thyroid,
thymie remains, left innominate vein; behind, trachea,
esophagus, thoracic duct; left side, left subclavian artery, left
vagus; right side, inferior ‘thyroid veins and innominate artery,
which is also somewhat in front.

In the neck each carotid ascends from the sternoclavicular
joint to the level of the upper border of the thyroid cartilage,
there dividing into the external and internal carotids. Each is
enclosed, with the internal jugular vein and vagus, in a sheath
of deep cervical fascia, the several structures being partitioned
from one another within the sheath. The artery is internal,
the vein external, the nerve between them, but in a posterior
plane.

Relations.—In front, integument, fascia, platysma, sterno-
mastoid, hyoid, thyroid, and omohyoid muscles, descendens and
communicans hypoglossi nerves, sternomastoid artery, superior,
middle thyroid, and anterior jugular veins, and a branch con-
necting anterior jugular with facial; behind, longus colli, rectus
anticus major, spinal column, inferior thyroid artery, sympathetic
and recurrent laryngeal nerves; outer side, internal jugular vein,
vagus; inner side, trachea, esophagus, larynx, pharynx, thyroid
gland, inferior thyroid artery, andrecurrent nerve. In the lower
part of the neck the internal jugular diverges from the artery on
the right side, but approaches, and may cross it, on the left.
The common carotid regularly gives off no branches, but a
vertebral, thyroid, or laryngeal branch may arise from it on
either side.

The external carotid artery runs from the bifurcation of the
common carotid to the space between the neck of the condyle
of the mandible and the auditory meatus, and there divides into
the superficial temporal and internal maxillary. At its origin

252 THE. VASCULAR SYSTEMS

it is anterior and internal to the internal carotid, and at its
termination is embedded in the parotid gland. :

Relations.—I/n front, integument and fascie, sternomastoid,
digastric, and stylohyoid muscles, part of the parotid gland,
facial and hypoglossal nerves, lingual, facial, and temporomaxil-
lary veins; behind, styloid process with its remaining muscles,
part of the parotid gland, and the glossopharyngeal nerve;
internally, pharynx, hyoid bone, part of the parotid, separat-
ing it from the lower jaw and stylomaxillary ligament, stylo-
glossus, and stylopharyngeus muscles, and the superior laryngeal
nerve.

The branches of the external carotid, besides those given off
directly to the muscles in its course and to the parotid gland,
are the following: Anterior branches, superior thyroid, lingual,
facial; posterior branches, occipital, posterior auricular; internal
branch, ascending pharyngeal; terminal branches, superficial
temporal and internal maxillary. |

I. The superior thyroid runs beneath the omohyoid and sterno-
hyoid and thyroid muscles to the gland, uniting with its fellow —
and with the inferior thyroid. It supplies the gland, the muscles
in its course, and the following named branches:

(a) Hyoid, to lower border of the bone, joins its fellow.

(b) Superficial descending or sternomastoid crosses the common
carotid to the sternomastoid muscle.

(c) Superior laryngeal, beneath the thyrohyoid, pierces mem-
brane to interior of the larynx with the superior laryngeal nerve.

(d) The cricothyroid runs across that membrane and joins its
fellow.

II. The lingual ascends to the great cornu of the hyoid bone,
runs forward parallel with it, ascends to the tongue, and runs
along its under surface to the tip. It is at first superficial, lying
on the middle constrictor; later covered by the digastric and
stylohyoid, resting on the same muscle. It then ascends be-
tween the hyoglossus and genioglossus; finally, as the ranine
artery, it runs on the lingualis to the tip of the tongue, along
with the gustatory nerve, covered only by mucous membrane.
The first part is crossed by the hypoglossal nerve. , The second
part is in the triangle formed by the diverging bellies of the
digastric below and the hypoglossal nerve above. The artery
lies above the central tendon of the digastric, below the nerve,
and beneath the hyoglossus. Branches:

THE BRANCHES OF THE ARCH OF THE AORTA 2538

(a) Hyoid, to upper border of the hyoid bone, joins its fellow.

(b) Dorsalis lingue, from beneath the hyoglossus, joins its
fellow, and supplies the tonsil, epiglottis, and soft palate, be-
sides the tongue.

(ec) Sublingual runs on genioglossus to the gland. Branches
supply the mylohyoid and gums, and a twig joins its fellow
across the middle line.

III. The facial runs below the lower jaw upon the mylohyoid,
and grooves the upper and back part of the submaxillary gland.
It then crosses the jaw at the anterior border of the masseter,
runs over the cheek by the angle of the mouth, and alongside
of the nose to the inner canthus of the eye, ending in the
angular artery, which anastomoses with the nasal branch of
the ophthalmic. Its course is very tortuous. |

This vessel lies at first beneath the digastric and stylohyoid,
but is covered only by the platysma where it crosses the jaw.
In the face it lies on the buccinator, levator anguli oris, and
levator labii superioris. covered by the platysma, risorius, and
zygomatici. The vein is external and at some distance from the
artery, and pursues a straight course. Branches of the facial
nerve cross, and the infraorbital nerve is under, the artery.

The branches of the facial artery are the following: A cervical
group, including the ascending palatine, tonsillar, submaxillary,
submental; and a facial group, the inferior labial, coronary
upper and lower, lateralis nasi, and the angular and the mus-
cular branches.

IV. The occipital artery is at first covered by the digastric
and stylohyoid muscles and crossed by the hypoglossal nerve.

~ It then crosses the internal carotid sheath and spinal accessory
nerve to the interval between the atlas and mastoid process,
lying here in the occipital groove of the mastoid process, and

- then pierces the origin of the trapezius to ramify in the scalp
as high as the vertex. Branches: Muscular, the sternomastoid,
the mastoid, princeps cervicis, and the meningeal.

V. The posterior auricular artery, resting on the styloid pro-
cess, passes beneath the parotid to the groove between the
mastoid and auricle, and divides into two branches, the auric-
ular and the mastoid, the latter supplying the scalp. This artery
crosses the spinal accessory and is crossed by the facial nerve.

VI. The ascending pharyngeal ascends between the pharynx
and internal carotid to the base of the skull, giving off branches

254 THE VASCULAR SYSTEMS

which may be divided into three sets, viz., (1) three or four
pharyngeal, to the constrictors, the lower joining branches of
the superior thyroid, and the largest to the superior constrictor,
supplying also the palate and tonsil. (2) Several meningeal
branches entering the foramen lacerum medium, jugular, and
anterior condylar foramina. (3) The prevertebral branches, to
the muscles and glands in its course and to the vagus and sym-
pathetic nerves, anastomosing with the ascending cervical.

The external carotid divides into the superficial temporal and
internal maxillary while embedded in the parotid gland, the
former being the smaller.

VII. The superficial temporal ascends about 2 inches above
the zygoma, and divides into the anterior and the posterior
tempora'. The former supplies the muscles, pericranium, and
skin over the forehead, joining the supraorbital and frontal;
the latter runs upward and backward over the side of the head,
anastomosing with its fellow, the occipital, and posterior auri-
cular. ‘The temporal supplies the articulation of the jaw, the
parotid, and the muscles in its course, and gives off the following
named branches: (a) The transverse facial, (b) the middle
temporal, and (c) the anterior auricular.

VIII. The internal maxillary is described in three portions—
viz., maxillary, pterygoid, and sphenomaxillary. The first
portion runs between the jaw and internal lateral ligament.
The second runs forward and upward upon the external ptery-
goid. The third enters the sphenomaxillary fossa between the
two roots of the external pterygoid.

Branches.—From the first or maxillary portion the tympanic,
middle and small meningeal, inferior dental; from the second or
pterygoid part the deep temporal, pterygoid, masseteric, buccal;
from the third or sphenomaxillary part the alveolar, infra-
orbital, superior or descending palatine, Vidian, pterygopalatine,
sphenopalatine.

(a) The tympanic, through the Glaserian fissure, joins the
stylomastoid and the tympanic arteries, and supplies a deep
auricular branch.

(b) The middle meningeal ascends between the roots of the
auriculotemporal nerve, through the foramen spinosum, and
divides on entering the cranium into an anterior and a posterior
branch. ‘These ramify on the inner surface of the calvaria as
far as the frontal and the occipital bones, uniting with the

THE BRANCHES OF THE ARCH OF THE AORTA 255

posterior and anterior meningeal. Branches pass to the Gas-
serian ganglion and dura mater; through the sphenoidal fissure
to the orbit; and through the hiatus Fallopii a petrosal branch
passes to join a branch of the stylomastoid artery.

(c) The small meningeal enters the foramen ovale, sometimes
arising from the preceding.

(d) The inferior dental traverses the dental canal, escaping
at the mental foramen. It sends forward an incisor branch in
the bone, gives off to the groove a mylohyoid branch, and unites
with its fellow and with the submental and labial arteries.
It supplies the teeth by small twigs to the roots from below.

(e) The two deep temporal anterior and posterior, join other
temporal branches. The anterior sends twigs through the
malar bone to unite with the lacrymal.

(f) The pterygoid branches supply the muscles of that name.

(g) The masseteric crosses the sigmoid notch to the deep
surface of the muscle.

(h) The buccal, on the buccinator, joins branches of the facial.

(4) The alveolar sends branches through the posterior dental
canals to the molar and bicuspid teeth, the antrum and gums.

(7) The infraorbital arises with the preceding, traverses the
canal, supplying the orbital muscular branches and an anterior
dental, and, escaping at the infraorbital foramen, supplies the
lacrymal sac, sending branches all over the face. It joins
branches of the facial and ophthalmic arteries.

(k) The descending palatine enters the posterior palatine
canal, and runs along the hard palate to the anterior palatine
foramen, thence through Stenson’s foramen to join the naso-
palatine artery. -It sends branches through the accessory pala-
tine canals to the soft palate.

(l) The Vidian passes through its canal to the pharynx and
Eustachian tube, and gives a branch to the tympanum.

(m) The pterygopalatine, through its canal to the sphenoidal
sinus and pharynx.

(n) The nasal, or sphenopalatine, through that foramen to
the spongy bones, ethmoidal cells, and antrum. One large
branch, the artery of the septum or nasopalatine, unites with
the termination of the descending palatine artery.

The internal carotid artery is a very tortuous vessel, and at
its origin is farther from the median line than the external
carotid, deriving the name “internal” from its distribution.

256 THE VASCULAR SYSTEMS

For description it is divided into four parts; the first, or cervical,
extends from the bifurcation of the common carotid to the caro-
tid canal; the second, or petrous, is in the carotid canal; the
third, or cavernous, runs in the cavernous sinus; and the fourth,
or cerebral, is the terminal portion.

Relations.—Cervical portion in front, external carotid artery
and its occipital and posterior auricular branches; hypoglossal,
glossopharyngeal nerves, and pharyngeal branch of the vagus;
behind, rectus capitis anticus major, sympathetic and superior
laryngeal nerves; eaternally, skin and fasciz, sternomastoid,
digastric, and thie styloid process with its muscles, internal
jugular vein and vagus, both being in the same sheath with the
artery, but having each a separate investment, the nerve being
posterior to, and between, the artery and vein. Near the base
of the skull the spinal accessory, glossopharyngeal, the vagus,
and hypoglossal nerves emerge between the vein and artery.
Internally the pharynx and tonsil, ascending pharyngeal artery,
superior and external laryngeal nerves.

The petrous portion is at first in front of the tympanum and
internal ear, and then runs forward and inward to the inner
side of the foramen lacerum medium, and ascends, accompanied
by the sympathetic, to the cavernous sinus.

The cavernous portion lies on the floor of the sinus, surrounded
by the sympathetic, the sixth nerve being external. _

The cerebral portion pierces the dura mater internal to the
anterior clinoid process, lying at the inner extremity of the
Sylvian fissure, between the second and third nerves.

The Branches of the Internal Carotid Artery.—The first portion
gives no branches. The second sends a tympanic branch through
a foramen in the carotid canal. The third gives off the arterie
receptacula to the pituitary gland, Gasserian ganglion, the
cavernous and inferior petrosal sinuses. One of these branches
is the anterior meningeal. It also gives off the ophthalmic.

The ophthalmic artery passes through the optic foramen,
below and external to the nerve, then crosses the latter, and
runs beneath the superior oblique muscle to the inner angle
of the eye, and divides into the frontal and nasal: It gives off
two sets of branches, viz., orbital and ocular.

The orBITAL branches are the following:

(a) The lacrymal runs above the external rectus to the
gland, sending several malar branches through the bone to the

Tse

THE BRANCHES OF THE ARCH OF THE AORTA 257

temporal fossa and cheek, a branch back through the sphenoidal
fissure to join the middle meningeal, and several to the con-
junctiva and upper lid to join other palpebral vessels.

(b) The supraorbital, through the notch, joining the temporal

and facial branches.
Fia, 41

Nasal. Palpebratl.
Frontal. Supra-orbital.
! |

Anterior ethmoidal.

we. AES 7 a Temporal branches

Posterior ethmoidal. of lachrymal.

Muscular.

i Pl —— Internal carotid
PA

The ophthalmic artery and its branches, the roof of the orbit having been removed.

(ec) The ethmoidal branches, posterior and anterior, run
through the ethmoidal canals to the ethmoidal cells. The former
supplies also the roof of the nose; the latter runs with the nasal
nerve, and divides into a meningeal and a nasal branch.

(d) The palpebral branches, superior and inferior, form arches
on the lids between the orbicularis muscle and tarsal cartilages,

17

258 THE VASCULAR SYSTEMS

the inferior sending a branch to the nasal duct. They anas-
tomose with the orbital branch of the temporal and with the
infraorbital artery.

(e) The frontal, at the inner angle of the orbit, unites with
the supraorbital.

(f) The nasal crosses the tendo oculi to the lacrymal sac, and
gives off the dorsalis nasi branch. It joins the angular artery.

(g) The muscular branches supply the muscles of the eyeball.
They are superior and inferior, and belong to the ocular group.

The other OcULAR branches are:

(h) The arteria centralis retine, within the optic nerve to the
retina.

(1) The ciliary pierce the sclerotic to supply the iris, ciliary
body, and choroid. They are derived from the ophthalmic
directly or from some of its branches, and are divided into the
anterior set, six to eight in number; the short, ten to fifteen;
and the long, two in number.

The fourth portion of the internal carotid supplies the follow-
ing branches:

(a) The anterior cerebral, along the front part of the great
longitudinal fissure, and is joined, by the anterior communicating,
with its fellow. The two vessels then, side by side, curve
around the front of the corpus callosum and run back over its
upper surface, breaking up into terminal branches which supply
the anterior cerebral lobes, anterior locus perforatus, and the
optic nerves.

(b) The middle cerebral, along the Sylvian fissure to the island
of Reil, supplying the pia mater over the anterior and middle
lobes, as well as the anterior perforated space.

(c) The posterior communicating, running back to join the
posterior cerebral.

(d) The anterior choroid, to the descending horn of the lateral
ventricle, sending branches to the choroid plexus, velum, and
hippocampus major.

The subclavian arteries are divided into three parts: the first
running to the inner margin of the scalenus anticus; the second,
behind that muscle; the third, from its outer border.to the lower
border of the first rib, where it becomes the axillary artery.
The right and left vessels differ only in their first portions,
the right arising behind the sternoclavicular joint, from the
innominate; the left, from the aorta as a primary branch.

THE BRANCHES OF THE ARCH OF THE AORTA 259

First Portion of the Right Subclavian.—Relations.—In front,
the sternomastoid, hyoid, and thyroid muscles; deep cervical
fascia; internal jugular, vertebral, and right innominate veins;
and superficially, the anterior jugular vein, some loops of the
sympathetic nerve and its cardiac branches, the vagus and
phrenic nerves; behind, the transverse process of the seventh
cervical or first dorsal vertebra, longus colli, recurrent laryngeal,
and sympathetic nerve and pleura; below, the pleura and recur-
rent nerve. -

First Portion of the Left Subclavian.—Relations.—In front, the
left lung and pleura, left carotid artery; internal jugular, verte-
bral, and left innominate veins; vagus, phrenic, and cardiac
nerves; and superficially, the sternothyroid, hyoid, and mastoid
muscles; behind, the sympathetic nerve, esophagus, and thoracic
duct, the longus colli separating it from the spine; externally,
the pleura; internally, the trachea, esophagus, and thoracic duct.

Second Portion of the Subclavian.—Relations.—In front, the
scalenus anticus, phrenic nerve, and the vein; behind and below,
the pleura.

Third portion of the Subclavian.—Relations.—In front, the
clavicle, subclavius, cervical fascia, suprascapular artery, ex-
ternal jugular, suprascapular, and transverse cervical veins,
supraclavicular nerves from the cervical plexus, and the nerve
to the subclavius; behind, the scalenus medius; above, the
omohyoid, brachial plexus; below, the first rib.

The branches of the subclavian are the vertebral, thyroid axis,
internal mammary, and superior intercostal. They are all
derived from the first portion on the left side; on the right the
superior intercostal arises from the second portion.

I. The vertebral, the first and largest branch, comes off from
the upper and back part of the first portion and enters the trans-
verse foramen of the sixth cervical vertebra, ascends through
those of the other cervical vertebre, and, grooving the upper
border of the atlas from without, backward, and inward, around
the superior articular process, pierces the dura mater. It then
ascends to the front of the medulla through the foramen mag-
num, uniting at the lower border of the pons with its fellow to
form the basilar. The thoracic duct crosses the left artery.
It is at first behind the internal jugular and its own vein; then
between the scalenus anticus and longus colli. In the foramina

260 THE VASCULAR SYSTEMS

it is accompanied by a sympathetic plexus, it is in front of the
spinal nerves, and it crosses the suboccipital nerve on the atlas.

Branches.—The cervical branches are muscular, to the deep
cervical region, joining the occipital and deep cervical; and the
lateral spinal, entering the intervertebral foramina.

The cranial branches include:

(a) The posterior meningeal, to the falx cerebelli and cerebellar
fossee.

(b) The anterior spinal, along the front of the medulla, joins
its fellow to form the upper part of the anterior median artery
of the cord. This is a small vessel which runs in the anterior
median fissure of the cord, beneath the pia mater, as far as the
cauda equina. 3

Fig. 42

Plan of the branches of the right subclavian artery.

(c) The posterior spinal descends along the posterior nerve
roots to the cauda equina. It is formed in a similar manner to
the anterior, but it is bilateral. |

(d) The posteroinferior cerebellar divides under the cerebellum
into two branches. The inner runs to the notch between the
hemispheres; the outer, to their under surface and the choroid
- plexus of the fourth ventricle, joining the superior cerebellar.

The basilar artery, formed by the two vertebrals, runs to the
upper border of the pons, and divides into the two posterior
cerebrals. ‘It gives off the following branches;

THE BRANCHES OF THE ARCH OF THE AORTA 261

(a) Several transverse arteries on each side. One, the auditory,
enters the internal meatus; another, the anteroinferior cerebellar,
to the anterior border of the cerebellum.

(b) The superior cerebellar, to the upper surface, joining the
inferior cerebellar.

(c) The posterior cerebrals, to the under surface of the posterior
lobes, receiving the posterior communicating. They give off the
posterior choroid branches and supply the posterior perforated
space.

The circle of Willis is situated at the base of the brain, it is
an anastomosis formed by the bloodvessels of the brain. The
arteries entering into its formation are: Jn front, the two anterior
cerebral arteries, branches of the internal carotid, which are
connected by the anterior communicating artery; behind, by
two posterior cerebral arteries, branches of the basilar, and these
communicate laterally with the internal carotids through the
posterior communicating arteries. The parts of the brain
included within this arterial circle are: The lamina terminals,
the chiasm of the optic nerves, tuber cinereum, corpora albi-
cantia, and the posterior perforated substance. .

II. The thyroid axis arises from the forepart of the subclavian,
and divides close to its origin into the inferior thyroid, supra-
scapular, and. transverse cervical.

1. The inferior thyroid, to the gland behind the sympathetic
and the common carotid, joins its fellow and the superior thyroid,
giving off the following branches:

(a) Inferior laryngeal, runs with the recurrent nerve; (b)
tracheal, joining the bronchial arteries; (c) esophageal; (d) to
the inferior constrictor and hyoid depressor muscles and the
scaleni; and (¢) the ascending cervical.

The last named runs between the scalenus anticus and the
rectus anticus major, joining the vertebral and giving other
branches which, with the lateral spinal of the vertebral, help
form the anterior median artery of the cord.

2. The suprascapular runs at first between the scalenus anticus
and the sternomastoid, crosses the subclavian, and runs behind
the clavicle to cross the transverse ligament of the scapula.
In the supraspinous fossa it runs beneath the muscle, which it
supplies, and crossing the neck of the scapula terminates in the
infraspinatus, where it joins the dorsal and posterior scapular
artery. A supraacromial branch joins the acromiothoracic

262 THE VASCULAR SYSTEMS

artery; a branch supplies the shoulder-joint, and another the
subscapular fossa.

3. The transverse cervical divides at the anterior border of the
trapezius into a superficial cervical branch, ascending beneath
and supplying that muscle, and a posterior scapular running
along the posterior border of the scapula to join the subscapular
artery at its inferior angle.

III. The internal mammary descends from the under surface
of the subclavian opposite the thyroid axis along the hinder
surface of the costal cartilages, } inch from the sternum, as far
as the sixth interspace, and divides into the musculophrenic and
superior epigastric. At first, behind the subclavian vein and the
phrenic nerve, it lies against the pleura, but separated from it
below by the triangularis sterni.

Branches.—(a) Comes nervi phrenici, to the diaphragm along
with the nerve, joins the phrenic arteries; (b) mediastinal; (c)
pericardiac; (d) sternal; (e) anterior intercostal; (f) anterior or
perforating; (g) musculophrenic; (h) superior digastric.

IV. The superior intercostal crosses in front of the neck of the
first rib, and supplies the first and part of the second interspace.

Its profunda cervicis branch passes backward between the
seventh cervical vertebra and the first rib, ascends under the
complexus to the axis, and joins the princeps cervicis and ver-
tebral arteries.

THE ARTERIES OF THE UPPER EXTREMITY

The Axilla

The axilla is a four-sided pyramidal space, of which the sides
are unequal, situated between the upper lateral aspect of the
chest and the arm. Its apex is between the first rib, the clavicle,
and the upper margin of the scapula. The base is directed down-
ward and outward, and is formed by the skin and fascia stretch-
ing across between the pectoralis major and the latissimus dorsi.
The anterior wall is formed by the pectoral muscles, the costo-
coracoid membrane, the clavicle, and the subclavius muscle.
The postertor wall extends lower than the anterior, and is formed
by the subscapularis above, the teres major and latissimus below.
The inner wall is convex. It is formed by parts of the first four

THE AXILLARY ARTERY 263

ribs, the portions of the intercostal muscles corresponding, and
a part of the serratus magnus. The outer wall is narrow, be-
cause of the convergence of the anterior and posterior walls.
It is formed by the humerus, coracobrachialis, and coracoid
head of the biceps.

This space contains the axillary vessels and brachial plexus,
with their branches, some branches of the intercostal nerve, and
_a large number of the lymph nodes and vessels and much fat.

The Axillary Artery

The axillary artery is the continuation of the subclavian. It
extends from the lower border of the first rib, where it is deeply
placed, to the lower border of the teres major tendon, where it
is superficial, and there becomes the brachial. It is described
in three parts—the first, above the pectoralis minor; the second,
behind it; and the third, below it.

First Part.—Relations.—In front, pectoralis major, subclavius,
costocoracoid membrane, acromiothoracic and cephalic veins,
external anterior thoracic nerve; behind, first intercostal muscle,
first digitation of the serratus magnus, posterior thoracic nerve;
externally, brachial plexus; internally, axillary vein, internal
anterior thoracic and posterior thoracic nerves.

Second Part.—Relations.—In front, pectoralis major and minor;
behind, subscapularis and posterior cord of the brachial plexus;
internally, vein and inner cord; externally, the outer cord.

The posterior cord of the plexus is behind it, the outer cord
outside, and the inner cord to its inner side. The plexus thus
surrounds the second portion of the artery.

Third Part.—Relations.—Infront, ntegument, fasciz, pectoralis
major, median nerve, its inner head, internal cutaneous nerve;
behind, subscapularis, tendons of the latissimus dorsi and teres
major, musculospiral and circumflex nerves; externally, coraco-
brachialis, musculocutaneous, and median nerves; internally, the
vein, brachial venze comites, ulnar and lesser internal cutaneous
nerves.

Branches.—First part, superior and acromial thoracic: second
part, long and alar thoracic; third part, subscapular and cir-
cumflex, posterior and anterior.

The subscapular runs along the lower border of the subscapu-
laris, joining branches with the intercostal and posterior scapular

264 THE VASCULAR SYSTEMS

arteries. Its dorsalis scapule branch passes through a triangle
formed by the two teres and the triceps, and divides into three
sets, viz., dorsal, to the infraspinous fossa; ventral, to the
subscapular fossa; and descending, to run between the teres
muscles.

The circumflex arteries encircle the neck of the humerus.
The posterior, with the nerve and veins, passes through the
quadrangular space formed by the triceps, teres, and humerus,
and ends in the deltoid and shoulder-joint. The anterior,
beneath the biceps and coracobrachialis, to end under the del-
toid, sends a twig to the shoulder-joint along the bicipital groove.

The Brachial Artery

The brachial artery extends from the end of the axillary,
at the lower border of the teres major, to $ inch below the elbow
joint, dividing into the radial and ulnar arteries.

Relations.—In front, integument and ‘fascia, bicipital fascia,
median basilic vein, and median nerve; behind, triceps, coraco-
brachialis, brachialis anticus, musculospiral nerve, and superior
profunda artery; externally, coracobrachialis, biceps, median
nerve above; internally, basilic vein, venze comites, internal
cutaneous, ulnar nerve, and median nerve below.

The branches of the brachial artery are:

(a) The superior profunda, along the musculospiral groove,
sends a branch of the shoulder-joint, anastomosing with the
circumflex; the posterior articular artery, to the back of the
elbow, joining the interosseous recurrent; branches to muscles;
and, finally, the continuation of the vessel joins the radial
recurrent in front of the outer condyle.

(b) The nutrient artery, to the humerus, enters the foramen.

(c) The inferior profunda, on the inner head of the triceps,
accompanies the ulnar nerve, and divides into a branch to the
front of the inner condyle and another to the back of it. The
former joins the anterior, and the latter the posterior ulnar
recurrent artery.

(d) The muscular branches, to the coracobrachialis, biceps,
and brachialis anticus.

(e) The anastomotica magna comes off about 2 inches above the
elbow and runs on the brachialis anticus inward to form an

THE RADIAL ARTERY 265

arch with the posteroarticular under the triceps. This artery
forms anastomoses with all the vessels around the elbow,
excepting only the radial recurrent.

The brachial divides, about 4+ inch below the elbow, into the
radial and ulnar arteries.

The antecubital space or fossa is situated at the bend of the
elbow. It is triangular in shape, the base corresponds to a line
drawn between the internal and external condyles of the
humerus; externally, the inner border of the brachioradialis or
supinator longus; internally, the inner border of the pronator
radii teres; its floor is covered by the supinator brevis and
brachialis anticus, and tendon of insertion of the biceps brachii;
it is enclosed by the deep fascia, a part of the bicipital fascia,
superficial fascia, and the integument. It contains the brachial,
radial, and ulnar arteries, and accompanying veins; the median
and musculospiral nerves. The median basilic vein is sepa-
rated from the brachial artery by the deep fascia of the
forearm, and the bicipital fascia beneath the latter.

The Radial Artery

The radial artery runs from the bifurcation of the brachial
along the radial side of the forearm to the wrist, and winds back
to its posterior surface. It then enters the palm through the
first dorsal interosseous, and runs across the hand to form the
deep palmar arch by joining the deep branch of the ulnar.

In the Forearm.—Relations.—I/n front, integument, fascia, and
supinator longus overlapping it; behind, from above downward,
it lies on the tendon of the biceps, supinator brevis, pronator
teres, flexor sublimis, flexor longus pollicis, pronator quadratus,
and radius; on the ulnar side, flexor carpi radialis and pronator
teres; on the radial side, supinator longus and radial nerve
(its middle third).

In the wrist it lies on the external lateral ligament, scaphoid,
and trapezium, and is covered by the extensors of the thumb,
cutaneous veins, and by filaments of the radial and musculo-
cutaneous nerves.

In the hand it lies on the metacarpal bones and interossei,
covered by the flexor tendons, opponens, flexor brevis minimi
digiti, and flexor brevis pollicis.

="

266 THE VASCULAR SYSTEMS

The branches of the radial artery are divided into three groups:

I. In the forearm: (a) The radial recurrent, between the supi-
nator longus and the brachialis anticus, joins the superior
profunda.

(b) The muscular, to the radial side of the forearm.

(c) The superficialis vole, through the muscles of the thumb;
sometimes it ends in them, or it may be very large, or may
complete the superficial arch. ,

(d) The anterior carpal runs inward to join in the anterior
carpal arch with the ulnar branch.

Il. In the wrist: (e) The posterior carpal joins the ulnar
branch, forming the posterior carpal arch. This arch gives off
the third and fourth dorsal interosseous branches.

(f) The metacarapl runs on the second dorsal interosseous
muscle, and joins, by branches, the first superior perforating
and palmar digital arteries. It divides into two dorsal digital
branches for the index and middle fingers, their adjacent sides,
and it also gives off an inferior perforating artery to the corre-
sponding palmar digital.

(g) Two dorsales pollicis, along the sides of the thumb.

(h) The dorsalis indicis, along the radial side of the index
finger.

III. In the hand: (i) The princeps pollicis, along the ulnar
side of the first metacarpal to the proximal phalanx, where it
divides into two branches for the palmar sides of the phalanges.

(j) The radialis indicis, along the radial border of the palmar
surface of the index finger.

(k) The superior perforating arteries pass back between the
heads of the last three dorsal interossei muscles to join the
dorsal interosseous arteries.

(l) Three or four palmar interosseous branches join the palmar
digital arteries at the finger clefts.

The Ulnar Artery

The ulnar artery runs along the inner side of the forearm to
the wrist, crosses the annular ligament and the palm of the hand,
and joins the superficialis vole to form the superficial arch.

In the Forearm.—Relations.—In front, integument, fascia, and
superficial flexor muscles, median nerve, and palmar cutaneous
branch of the ulnar nerve; behind, brachialis anticus, flexor

THE THORACIC AORTA 267

profundus digitorum; ulnar side, flexor carpi ulnaris, median
nerve above and ulnar nerve below; radial side, flexor sublimis.

At the wrist the nerve is internal to the artery, and the pisiform
bone is internal to the ulnar nerve.

In the hand, as the superficial arch, it is covered by the skin,
palmaris brevis, and palmar fascia. It rests on the annular
ligament, superficial tendons, and divisions of the median and
ulnar nerves.

The branches of the ulnar artery are divided into three groups:

I. Forearm: (a) The anterior ulnar recurrent, to front of the
inner condyle, joins the anastomotica magna and _ inferior
profunda.

(b) The posterior ulnar recurrent, beneath the flexor sublimis
to the back of the inner condyle, and between the heads of the
flexor carpi ulnaris along the ulnar nerve; joins the posterior
interosseous recurrent and inferior profunda arteries.

(c) The interosseous, to the upper border of the interosseous
membrane, where it divides into the anterior and posterior
interosseous arteries. ‘The anterior runs on the front of the
membrane, which it pierces above the pronator quadratus, to
_ join the posterior branch and the posterior carpal arch. It
supplies the median artery to the nerve, muscular branches, and
the nutrient vessels of the radius and ulna. A branch joins the
anterior carpal arch. The posterior interosseous descends along
the back of the forearm, between the superficial and deep
muscles, and joins the anterior. It gives off the interosseous
recurrent, which ascends beneath the anconeus to join, behind
the olecranon, in the anastomosis at the elbow-joint.

(d) The muscular, to the ulnar side of the forearm.

Il. Wrist: The anterior and posterior carpal join similar
branches of the radial to form the carpal arches, the posterior
giving a metacarpal branch to the little finger, ulnar side.

Ill. Hand: (a) The deep branch joins the radial to form the
palmar arch.

(b) The digital branches from the superficial palmar arch are
four, going to the little, ring, middle, and ulnar side of the index
finger.

The Thoracic Aorta

_ The thoracic aorta descends from the lower border of the fifth
to the front of the last dorsal vertebra.

268 THE VASCULAR SYSTEMS

-Relations.—I/n front, root of the left lung, pericardium, and
esophagus; behind, azygos minor vein and spinal column; fo the
left, left lung and pleura, and, below the esophagus; to the right
esophagus above, vena azygos major, thoracic duct.

The branches of the thoracic aorta:

(a) The PERICARDIAC.

(b) The BRONCHIAL, to the bronchial glands and the esophagus;
they are also the nutrient vessels of the lung. The right some-
times arises from the first aortic intercostal.

(c) Four or five: ESOPHAGEAL, joining the inferior thyroid
above, the gastric and phrenic below.

(d) The POSTERIOR MEDIASTINAL.

(e) The INTERCOSTAL. These are nine or ten, the superior
intercostal from the subclavian supplying the upper space or
two. They cross obliquely to the edge of the rib above, running
at first on the external, and then between the two sets of inter-
costal muscles.

Each divides into two branches running along the contiguous
borders of the two ribs, and each uniting anteriorly with the
corresponding branch of the anterior intercostals from the
internal mammary.

A posterior branch runs from each, and divides into a spinal
branch to the cord and a muscular branch.

The Abdominal Aorta

The abdominal aorta runs from the last dorsal to the left side
of the middle of the body of the fourth lumbar ‘vertebra, there
dividing into the two common iliacs.

Relations.—In front, lesser omentum, stomach, pancreas, trans-
verse duodenum, left renal and splenic veins, peritoneum form-
ing mesentery, aortic, and solar plexuses; behind, receptaculum
chyli, thoracic duct, left lumbar veins, and spine; to the right,
crus of the diaphragm, vena cava, great azygos vein, thoracic
duct, right semilunar ganglion, splanchnic nerve; to the left,
splanchnic nerve, left semilunar ganglion.

The branches of the abdominal aorta:

(a) Parietal and (6) visceral.

The parietal branches are: I. The phrenic, a right and a
left. Their origin is inconstant, from the aorta separately or
in common, or from one of its branches. They run across the

iad a. ee ee

THE ABDOMINAL AORTA 269

crura to the under surface of the diaphragm. Each supplies
suprarenal capsular branches, the right sending branches to the
liver and vena cava; the left, to the spleen and esophagus.

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The celiac axis and its branches, the liver having been raised and the lesser
omentum removed.

Il. The lumbar, five on each side, pass behind the psoas and
sympathetic, and divide into a dorsal branch to the baek, and
an abdominal branch running between the abdominal muscles,
joining branches of the epigastric, intercostal, iliolumbar, and
internal mammary. .

Ill. The middle sacral, along the middle of the front of the

sacrum to the coccyx, joining the lateral sacral and entering
Luschka’s gland,

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270 THE VASCULAR SYSTEMS

The visceral branches: I. The celiac axis, $ inch long, divides
into the gastric, hepatic, and splenic. It is covered by the lesser
omentum, rests below on the pancreas; on each side is a semi-
lunar ganglion, and on the right the lobus Spigelii, on the left
the stomach.

Branches.—(a) The gastric artery runs to the cardiac orifice,
thence to the right, along the lesser curvature, in the lesser
omentum as far as the pylorus. It supplies both surfaces of the
stomach and the esophagus, anastomosing with the splenic,

pyloric branch of the hepatic, and esophageal arteries.

(b) The hepatic artery passes below the foramen of Winslow
to the pylorus, then ascends in the lesser omentum, anterior to
that foramen, and to the left of the gall duct, to the transverse
fissure of the liver, and divides into a right and a left branch.
Its pyloric branch passes along the lesser curvature to meet the
gastric. Its cystic branch from the-right division’ ascends on
the neck of the gall-bladder and supplies it by two branches.
The other branch of the hepatic, the gastroduodenalis, divides
behind the lower part of the duodenum into a superior pancre-
aticoduodenal branch, descending between the pancreas and
duodenum to join the inferior artery of the same name; and the
gastroepiploica dextra, passing into the omentum toward the
left, along the great curvature, to meet the sinistra.

(c) The splenic runs tortuously to the left, along the upper
border of the pancreas, and divides near the spleen into branches
which enter at the hilum, some passing to the stomach.

Branches.—Pancreatic, numerous, small; and one larger, the
pancreatica magna, accompanies the duct of Wirsung.

Five to seven vasa brevia, in the gastrosplenic omentum, to the
great end of the stomach, joining the gastric and gastroepiploic
vessels.

The gastroepiploica sinistra runs to the right, along the great
curvature, to join the dextra.

II. The superior mesenteric supplies the small intestine except
the first part of the duodenum, as well as the cecum, and
ascending and transverse colon. Emerging from between the
transverse duodenum and pancreas, it crosses the former, and
descends in the mesentery to the right iliac fossa with its veins
and a plexus of nerves. It ends by anastomosing with its own
iliocolic branch.

me aoe

THE ABDOMINAL AORTA 271

Branches.—(a) The inferior pancreaticoduodenal, joining the
superior from the hepatic artery.

Superior mesenteric artery. (Testut.)

'(b) Twelve to fifteen vasa intestint tenuis to the jejunum and
ileum, running parallel within the mesentery, each vessel bifur-

272 THE VASCULAR SYSTEMS

cating. These divisions, uniting on each side with their fellows,
complete a series of arches from which are formed, similarly,

Fig. 45

Arteries of the stomach, liver, and great omentum. (Testut.)

THE ABDOMINAL AORTA 273

secondary arches. The terminal arches send numerous straight
vessels around the gut.

(c) The iltocolic divides near the right iliac fossa into two
branches. The inferior joins the termination of the superior
mesenteric; the upper joins the colica dextra. It supplies the
ileum, cecum, appendix, and ascending colon.

(d) The colica dextra, to the middle of the ascending colon,
divides into a lower branch joining the iliocolic, and an upper
which joins the colica media. These branches form arches from
which is supplied the colon.

(e) The colica media, to the transverse colon, divides into a
right branch joining the dextra; a left, the sinistra.

III. The inferior mesenteric supplies the descending colon and
its continuation. Arising from the left side of the aorta an inch
or two above the bifurcation, it passes to the left iliac fossa,
ending in the pelvis as the superior hemorrhoidal. It gives off
the following branches:

(a) The colica sinistra, to the descending colon, dividing into
an upper branch joining the media; a lower, the sigmoid artery.

(b) The sigmoid, to the flexure, joins the colica sinistra above
and the superior hemorrhoidal below.

(c) The superior hemorrhoidal, in the mesorectum, crosses the
left common iliac artery and vein. It divides into two branches,
one on each side of the rectum, which finally join the middle
and inferior hemorrhoidal arteries.

IV. The suprarenals, to the under surface of the suprarenal
capsules, join branches of the phrenic and renal arteries.

VY. The renal, to the hilum, enters by four or five branches
into which each vessel divides close to the kidney. They lie
between the veins in front and the ureters behind. Branches
pass to the suprarenal bodies and ureter. There may be more
than one renal on each side.

VI. The spermatic, the ovarian in the female, to the testicles
or ovaries respectively. Passing behind the peritoneum, they
cross the ureter and psoas, and in front of the vena cava on the
right, each crossing also the external iliac vessels. In the male
the vessel then runs through the inguinal canal to the testis,
joining the artery of the vas deferens. In the female it runs
in the broad ligament to the ovary, and sends branches to the
broad ligament, the tubes, and uterus.

18

274 THE VASCULAR SYSTEMS

The Iliac Arteries

The common iliac arteries run downward and outward from
the division of the aorta to the lumbosacral joint, and divide
into the external and internal iliacs.

Relations.—Each has in front the peritoneum, small intestine,
ureter, and sympathetic nerve; the left is crossed by the superior
hemorrhoidal artery; behind and to the inner side of each is its
vein, the right having both its own and the left vein between it
and the last lumbar vertebra, and external to each is the psoas
magnus. The right at its upper part has also the beginning
of the inferior vena cava posteriorly.

Branches.—Small twigs to the psoas, ureters, and lymphatic
glands.

The internal iliac artery descends to the upper part of the
great sacrosciatic foramen, and divides into an anterior and a
posterior trunk.

Relations.—Jn front, the ureter and peritoneum; behind, the
sacrum, lumbosacral cord, companion vein, and the external iliac
vein at its upper part; eternally, the vein; externally, the psoas
muscle. The posterror trunk gives off the following branches;

(a) the iliolumbar; (b) the lateral sacral; (c) the gluteal, passes.

through the great sciatic foramen, and divides into a superficial
and a deep branch.

The anterior trunk of the internal iliac gives off the following
branches:

(a) The superior vesical represents the pervious part of the

fetal hypogastric artery. It runs to the apex and body of

‘the bladder and to the ureter, joins its fellow, and gives off the
artery of the vas deferens, which accompanies that structure to
the testis. It also generally gives off the (6) middle vesical to
the base of the bladder.

(c) The inferior vesical—vaginal in the female—joins its fellow.
It supplies the bladder, prostate gland, and seminal vesicles;
in the female, vagina and rectum.

(d) The middle hemorrhoidal arises with the preceding, and
runs to the rectum to join other hemorrhoidal arteries.

(e) The uterine in the female ascends in the broad ligament
from the cervix along the side of the uterus and gives off a branch
to the ovary, which anastomoses with the ovarian artery;

4’

THE ILIAC ARTERIES 275

branches to the cervix of the uterus, cervicouterine, and a
branch which descends on the vagina, cervicovaginal, and, join-
ing with branches from the vaginal arteries, form a median
longitudinal vessel both in front and behind; these continue on
the anterior and posterior surfaces of the vagina, and are called
the azygos arteries of the vagina.

(f) The obturator runs forward below the pelvic brim, between
the peritoneum and pelvic fascia below the nerve, then through
the upper part of the obturator foramen, dividing beneath the
obturator externus into an external and an internal branch.
Skirting the edges of the foramen, they join below with each
other and the internal circumflex. The external also joins the
sciatic, and sends a branch along the ligamentum teres, through
the cotyloid notch, to the joint.

The termination of the anterior trunk of the internal iliac then
divides into two branches, the sciatic and the internal pudic
arteries. |

(g) The internal pudic escapes from the pelvis through the
great sciatic foramen, crosses the ischial spine, and re-enters the.
pelvis by the lesser foramen, then runs along the outer wall of
the ischiorectal fossa an inch and a half above the tuberosity,
and upon the rami of the ischium and pubes, to the subpubic
arch, where it divides into the artery of the corpus cavernosum
and the dorsal artery of the penis.

This vessel is at first in front of the pyriformis, the sacral
plexus intervening, and external to the rectum. On the ischial
spine it lies beneath the gluteus maximus, the pudic nerve
internally. In the ischiorectal fossa it lies on the obturator
internus, ensheathed by the obturator fascia, then between the
layers of the perineal fascia.

Branches,—(a) Two or three inferior hemorrhoidal, to skin and
muscles around the anus.

(b) The superficial perineal runs over or under the transversus
perinei to the back of the scrotum, sending branches to the
skin and muscles of the perineum.

(c) The transverse perineal, to the parts between the anus and
bulb, joins its fellow.

(d) The artery of the bulb runs in the constrictor urethree,
pierces the bulb, and sends a branch to Cowper’s gland.

(e) The artery of the corpus cavernosum runs forward in the
centre of that body after piercing the crus penis.

276 THE VASCULAR SYSTEMS

(f) The dorsal artery of the penis runs between the symphysis
and the penis to the glans and prepuce. Here it is superficial,
and lies upon the crus penis, pierces the suspensory ligament,
and runs along the dorsum between the median vein and the
corresponding nerve.

In the female the pudic artery is smaller, but has analogous
branches. The superficial perineal artery runs to the labia;
that of the bulb to the bulbus vestibuli; that of the corpus
cavernosum to the corresponding part of the clitoris; and the
dorsal artery to the glans clitoridis.

(g) The sciatic accompanies the pudic, resting on the pyri-
formis muscle and the sacral plexus, escapes by the great fora-
men, and descends, midway between the tuber ischii and the
trochanter major, with the sciatic nerves.

The branches are: (a) the coccygeal, (b) the muscular, (c) the
comes nervi ischiadici, (d) the anastomotic, (e) the articular
branches.

The external iliac artery extends from the division of the com-
mon iliac to the mid-point between the symphysis of the pubis
and the anterior superior spine of the ilium, behind Poupart’s
ligament.

Relations.—/n front, the peritoneum, subperitoneal fascia, sig-
moid flexure on the left, ileum on the right side, lymphatic
vessels and glands, spermatic or ovarian vessels, deep circum-
flex iliac vein, genital branch of the genitocrural nerve and, at
times, the ureter; behind, psoas muscle and iliac fascia and its
vein; internally, its vein and the vas deferens; externally, psoas
and iliae fascia.

The branches of the external iliac artery: (a) The deep epi-
gastric descends to Poupart’s ligament, then ascends, internal
to the deep ring, between the transversalis fascia and the peri-
toneum. It then pierces the fascia and enters the sheath of the
rectus, ascending on the posterior surface of the muscle, and
dividing into branches which join the superior epigastric. The
vas deferens in the male, round ligament in the female, cross the
vessel on its outer side at the internal ring.

Branches.—The cremasteric, to the cord; the abi to the
back of the pubis, joining the pubic of the ‘obturator; and the
muscular.

(b) The deep circumflex iliac passes to the anterior superior
spine in a sheath of the transversalis and iliac fascia, thence

THE FEMORAL ARTERY 277

along the inner margin of the crest. On a line with the anterior
superior spine of the ilium it ascends between the transversalis
and internal oblique muscles.

THE ARTERIES OF THE LOWER EXTREMITY

The Femoral Artery

The femoral artery continues the external iliac artery down
into the thigh to end at the opening in the adductor magnus
at the junction of the upper three-fourths and lower one-fourth
of the femur. From its beginning to the point where the pro-
funda femoris is given off, it is called the common femoral,
below this the superficial femoral. Its upper part lies in Scarpa’s
triangle, bounded above by Poupart’s ligament, the inner side
formed by the inner margin of the adductor longus, the outer
by the sartorius. Its floor, from without inward, is made up
of the iliacus, psoas, pectineus, and adductor brevis. The lower
part runs in Hunter’s canal, a depression between the vastus
internus and the adductores magnus and longus, covered by a
strong fascia passing between them, the latter covered by the
sartorius muscles.

Relations.—I/n front, fascia lata, crural sheath, fascia covering
Hunter’s canal, sartorius, internal cutaneous and long saphenous
nerves, nerve to the vastus internus, and filaments of the
crural branch of the genitocrural nerve, and a few superficial
veins; behind, psoas magnus, pectineus, adductores brevis,
longus and magnus, femoral vein and profunda vessels, branch
of the anterior crural nerve to the pectineus; outer side, anterior
crural nerve, vastus internus, and femoral vein below; inner side,
sartorius, adductor longus, femoral vein above.

The branches of the femoral artery are: (a) The superficial epi-
gastric rises about half an inch below Poupart’s ligament and
passes through the sphenous opening, ascends in the superficial
fascia over the abdomen, joining other epigastrics.

(b) The superficial circumflex iliac.

(c) The superior external pudic comes off from the inner side
of the common femoral a little below the preceding and passing
through the saphenous opening crosses to the lower abdomen

278 THE VASCULAR SYSTEMS

over the cord, supplying the penis and scrotum (the labium in
the female).

(d) The inferior external pudic arises close to the superior,
crosses the pectineus, pierces the fascia lata at the margin of
the groin, and supplies the perineum and scrotum ithe labium
in the female).

(e) The muscular branches all along its course.

(f) The anastomotica magna arises close to the adductor open-
ing, and divides into two branches: a deep, to the inner side of
the knee, joins the recurrent tibial and articular arteries, and a
superficial, which runs with the long saphenous nerve.

(g) The profunda artery arises from the femoral at its outer
and back part, one to two inches below Poupart’s ligament. It
at first runs outward, but afterward behind the femoral, then
beneath the adductor longus, terminating at the lower third
of the thigh by piercing the adductor magnus, becoming the
lowest perforating artery.

Relations.—Jn front, adductor longus, femoral and profunda
veins; behind, iliacus, pectineus, adductores magnus and brevis;
externally, vastus internus.

Branches.—The external circumflex runs beneath the sartorius
and rectus, and divides into—ascending branches, under the
tensor vaginze to join the gluteal and deep circumflex iliac
arteries; descending branches, running upon the vasti, some
passing beneath to the knee, to join the articular arteries;
transverse, piercing the vastus externus to the back of the femur,
and joining the superior perforating.

The internal circumflex runs between the psoas and pectineus,
and supplies the adductor and obturator muscles and an artic-
ular twig to the hip-joint, under transverse ligament. It then
joins in the crucial anastomosis, which is situated in. the upper
part of the thigh posteriorly, covered by the gluteus maximus.
It is formed by the joining of this artery with the sciatic from
above, the superior perforating below, and the external circum-
flex to the outer side.

The perforating pierce the short and great adductor muscles
close to the femur, to the back of the thigh, anastomosing freely
with each other and with the popliteal below. ‘The superior
enters into the crucial anastomosis. ‘The first arises above the
adductor brevis, the second opposite, the third below it. The
second or third gives the nutrient artery to the femur. The ter-
mination of the profunda is called the fourth perforating.

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THE POPLITEAL ARTERY 279

The Popliteal Space

The popliteal space is lozenge-shaped, being widest at the
back part of the knee-joint and deepest above the articular
end of the femur. It is bounded externally, above the joint, by
the biceps, and below the joint by the plantaris and external
head of the gastrocnemius; internally, above the joint, by the
semitendinosus, semimembranosus, 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.

The Popliteal Artery

The popliteal artery runs from the adductor opening to the
lower border of the popliteus, where it divides into the anterior
and posterior tibial.

Relations.—/n front, femur, ligamentum posticum, popliteus;
behind, semimembranosus, fascia, gastrocnemius, plantaris, and
soleus, popliteal and short saphenous veins, and the internal
popliteal nerve; outer side, external condyle, outer head of the
gastrocnemius, plantaris, internal popliteal nerve above; inner
side, inner condyle, inner head of the gastrocnemius, semi-
membranosus, popliteal vein, and the internal popliteal nerve
below.

The branches of the popliteal artery are:

(a) Muscular superior, three or four, to the lower part of the
hamstring muscles to join the inferior perforating; inferior
(sural), to the upper part of the gastrocnemius, plantaris, and
soleus.

(b) Cutaneous to the skin of the calf.

(c) Articular superior, two in number, an external and an
internal, wind around above the condyles to the front. The
external gives a branch to the external vastus and one to the
joint, and also forms an arch with the anastomotica. The in-

280 THE VASCULAR SYSTEMS

ternal gives a branch to the internal vastus, joining anastomotica
and inferior articular, and another to the knee-joint, and also
unites with the inferior articular.

(d) The azygos articular pierces the posterior ligament to the
joint.

(e) Articular inferior wind around the tibia below the joint.
They are external and internal, and anastomose with the tibial
recurrent, anastomotica, and other articular branches.

The anterior tibial artery runs from the lower border of the
popliteus, between the heads of the tibialis posticus and above
the interosseous membrane, to the front of the leg, then descends
as far as the ankle, ending in the dorsalis pedis.

Relations.—J/n front, integument, fascia, tibialis anticus, exten-
sores proprius pollicis and longus digitorum, anterior tibial
nerve; behind, interosseous membrane, tibia, anterior tibiotarsal
ligament; outer side, extensores proprius pollicis and longus
digitorum, anterior tibial nerve; inner side, tibialis anticus,
tendons of extensor proprius pollicis below.

Its branches are:

(a) The recurrent tibial, through the tibialis anticus to the
knee, joins other articular arteries.

(b) The muscular, to the muscles and skin: very numerous.

(c) The malleolar, to the ankle-joint. Internal joins corre-
sponding branches of the posterior tibial; external joins the tarsal
and anterior peroneal.

The dorsalis pedis is the continuation of the anterior tibial,
and runs from the bend of the ankle to the first interosseous
space, where it divides into the dorsalis hallucis and plantar
digital.

Its branches are:

(a) The tarsal.

(b) The metatarsal, over the bases of the metatarsal bones,
joins the tarsal and external plantar, and gives off three dorsal
interosseous arteries which run in the outer three intermetatarsal
spaces, each dividing opposite the metatarsophalangeal joint
into two dorsal digital branches. These arteries anastomose at
back part of spaces with the posterior perforating, and at front
part with the anterior perforating.

(c) The dorsalis hallucis lies along the first intermetatarsal
space, and supplies both sides of the great toe and the inner side
of the second dorsally.

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THE POPLITEAL ARTERY 981

(d) The plantar digital passes between the heads of the first
dorsal interosseous, joins with the external plantar to form the
plantar arch, and after supplying the inner-side of the great
toe divides into two branches for the adjacent sides of the
great and second toes.

The posterior tibial artery runs from the lower border of the
popliteus to divide, between the inner malleolus and heel, into
the eaternal and internal plantar arteries.

Relations.—I/n front, tibialis posticus, flexor longus digitorum,
tibia, and ankle joint; behind, skin, fascia, gastrocnemius, soleus,
deep transverse fascia, posterior tibial nerve. This nerve is
internal in its upper part, but lower down it is external to the
artery.

Its branches are:

(a) The peroneal runs from one inch below the popliteus to the
lower third of the leg, and divides into the anterior and posterior
peroneal. It is covered by the soleus and deep transverse fascia;
in front of it are the tibialis posticus and interosseous membrane:
external to it, the fibula; and externally, as well as behind, the
flexor longus pollicis.

The peroneal gives off muscular branches and a nutrient artery
to the fibula. The anterior peroneal passes beneath the inter-
osseous membrane to the front of the leg, and runs to the outer
ankle to join the tarsal and external malleolar. The posterior
peroneal passes down behind the external malleolus, and termi-
nates in branches (eaternal calcaneal) which anastomose with
the external malleolar.

(b) The nutrient artery for the tibia.

(c) The muscular branches.

(d) The communicating.

(e) Several internal malleolar.

The plantar arteries are the terminal branches of the posterior
tibial. The internal is at first under cover of the abductor
pollicis, and then between it and the flexor brevis digitorum,
anastomosing at the inner border of the great toe with its
digital artery.

The external, the larger, passes to the base of the fifth meta-
tarsal, then to the space between the first and second meta-
tarsals, and joins the plantar digital, from the dorsalis pedis,
to form the plantar arch.

The plantar arch supplies the muscles, fascia, and skin of the

282 THE VASCULAR SYSTEMS

sole of the foot, and gives off the posterior perforating. These
pierce the three outer spaces between the heads of the dorsal
interossei and join. the dorsal interosseous arteries.

Fia. 46

Communicating
branch of

dorsalis pedis.
Its digital
branches.

The plantar arteries. Deep view.

The digital, four in number, supply the three outer toes and
the outer half of the second toe; the first runs to the outer side
of the little toe, the others bifurcate to the adjacent sides of the
fourth and fifth, fourth and third, third and second toes. At
the point of bifurcation each sends a small branch to join the
dorsal interosseous arteries (anterior perforating).

5
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;

THE SYSTEMIC VEINS | 288

THE VEINS

The veins, like the arteries, are of two great systems, the
pulmonary and the systemic.

THE PULMONARY VEINS

These are four large trunks, two on each side, which return
the blood from the lungs to the left auricle. On the right side
they pass behind the right auricle and superior vena cava; on
the left, in front of the descending aorta. The upper right vein
receives the branch from the middle lobe.

THE SYSTEMIC VEINS

The veins of the heart are:

The great cardiac vein ascends in the anterior interventricular
groove from the apex of the heart to the left auriculoventricular
groove; along this latter it runs to the posterior surface of the
heart, to end in the coronary sinus. At its termination it is
provided with a valve.

Three or four posterior cardiac veins ascend on the left
ventricle to the sinus.

The middle cardiac vein ascends in the posterior interven-
tricular groove to the sinus.

The right (small) coronary vein in the right auriculoventric-
ular groove to the sinus.

The coronary sinus, one inch long, is placed at the back part of
the auriculoventricular groove, on the left side, and opens into
the right auricle in front of the inferior vena cava. Besides the
foregoing veins, it receives the oblique vein of Marshall, which
drains the back of the left auricle. Its opening is guarded by the
Thebesian valve.

The other cardiac veins are several small vessels from the
front of the right ventricle, the anterior cardiac veins, opening
directly into the auricle, and the ven Thebesii, in the muscular
substance, which open by minute orifices, the foramina Thebesii,
near the septum auricularum.

284 _. THE VASCULAR SYSTEMS

The Superior Vena Cava and Innominate Veins

The superior vena cava is a large trunk formed by the union
of the two venz innominate, and returns the blood from the
head and neck, the thoracic walls, and the upper extremities.
It is about three inches long, and descends from the junction of
the first right costal cartilage with the sternum to its termin-
ation in the right auricle, opposite the upper border of the third
right cartilage.

At first it is external to the innominate artery and internal
to the right phrenic-nerve, partly covered by the pleura. It
then pierces the pericardium external to the ascending aorta,
having descended in front of the right division of the pulmonary
artery. It receives the azygos major and small pericardiac
and mediastinal veins.

The innominate veins, formed by the union of the subclavian
and internal jugular of each side, behind the inner end of the
clavicle unite to form the superior vena cava. The right vein,
one inch long, descends vertically on the right side of the innomi-
nate artery, while the left, more than two inches in length,
descends slightly, running to the right, behind the sternohyoid
and thyroid muscles and upper part of the sternum. The
transverse aorta lies below it.

Each receives the vertebral, inferior thyroid, and internal
mammary veins. The left vein also receives the superior inter-
costal and some small thymic, mediastinal, and pericardiac veins
and the thoracic duct, while the right is joined at its origin by
the right lymphatic duct.

The vertebral vein descends with the artery of the same name
through the foramina in the transverse processes of the upper
six cervical vertebree, crosses the subclavian artery, and opens
into the back part of the vena innominata.

The inferior thyroid veins arise by tributaries from the lateral
lobes of the thyroid gland, and descend on the trachea beneath
the sternothyroid muscles. The left joins the innominate on
its own side, sometimes in common with the right. The latter
may empty into the junction of the two ven innominate or
join the right vena innominata.

The internal mammary veins are two on each side, and accom-
pany the artery, receiving corresponding tributaries, finally

THE VEINS OF THE HEAD AND NECK 285

uniting to form a single trunk which joins the corresponding
innominate.

The superior intercostal vein drains the two or three spaces
below the first, and enters on the right side the large azygos;
on the left side it communicates with the left upper azygos and
joins the innominate.

THE VEINS OF THE HEAD AND NECK

The facial vein runs from the inner angle of the eye to the
anterior border of the masseter muscle, then backward below
the jaw, joining the anterior division of the temporomaxillary
trunk to form the common facial, which joins the internal
jugular. It sends a communicating tributary along the front of
the sternomastoid to the anterior jugular. At its origin it is
continuous with the angular, a vein formed by the union of
the frontal and supraorlital.

The temporomaxillary vein (posterior facial) is a short trunk,
formed by the temporal and internal maxillary veins, runs from
opposite the condyle of the lower jaw to the angle of the jaw,
and divides into an anterior branch joining the facial and a
posterior branch running backward to form with the posterior
auricular the external jugular. This vein is embedded in the
parotid gland external to the external carotid artery.

The temporal vein is formed by the union of the superficial
with the middle temporal vein, and crosses over the zygoma and
under the parotid to join the internal maxillary vein. It
receives the anterior auricular, parotid, and transverse facial veins,
and tributaries from a plexus around the articulation of the
jaw.

The internal maxillary vein arises from the pterygoid plexus
and runs in company with the first part of the artery, joining
the temporal vein behind the ramus of the jaw.

The posterior auricular vein descends over the mastoid process
and sternomastoid and ends in the external jugular.

The occipital veins, two or three, join the deep cervical vein.

The emissary vein in the mastoid foramen connects the lateral
sinus with the most external of the occipital veins.

The external jugular vein is formed by the union of the pos-
terior auricular and the posterior division of the temporo-

986 THE VASCULAR SYSTEMS:

maxillary trunk. It descends obliquely across the sterno-
mastoid, lying between the platysma and fascia. Above the
clavicle it pierces the fascia and joins the subclavian at the outer
border of the scalenus anticus; sometimes it joins the internal
jugular. It receives the posterior external jugular, anterior
jugular, transverse cervical, and swprascapular veins. The two
latter correspond to the arteries of the same name.

The posterior external jugular drains the occipital and pos-
terior cervical regions.

The anterior jugular descends along the front of the neck
from the submaxillary region, pierces the fascia near the inner
end of the clavicle, and joins the external jugular, sometimes
the subclavian. This vein and its fellow are joined by a cross-
branch just above the sternum, and it receives tributaries of
communication from the submental, external jugular, and facial.

The internal jugular vein commences at the jugular foramen
just below the junction of the inferior petrosal with the lateral
sinus, and descends with the external carotid, then with the
common carotid, to join at a right angle with the subclavian vein
behind the clavicle, thus forming the innominate vein. It is
placed external to the carotid vessels, lying in the same sheath
with each in turn.

It receives the following tributaries:

The common facial (vide antea) and the middle thyroid.

The superior thyroid.

The pharyngeal veins.

The lingual veins, including the ranine, dorsal vein of the tongue,
and the vene comites of the lingual artery.

The inferior petrosal sinus is Reape by some anatomists as
the first tributary.

The cerebral veins. These are divided into two sets, the
superficial and the deep.

Superficial Veins.—The superior, ten to twelve on each side,
consist of the anterior, middle, and posterior veins which run
in the sulci, and, joining with branches from the mesial aspect
of the brain, empty into the superior longitudinal sinus. The
inferior consists of the middle cerebral vein, in the Sylvian
fissure, which joins the cavernous sinus, and the great anasto-
motic vein, in the posterior branch of the same fissure, communi-
cating with the middle meningeal veins and joining the superior
petrosal sinus.

—_ See.

ti). Ba

ee es ee Le Se eee ee a a a ee
St tS als iad ’
1 7 ; a '

THE VEINS OF THE HEAD AND NECK 287

Deep Veins.—They finally converge to two trunks, the vena
Galent. ‘These run backward in the velum interpositum, the
right and left, lying side by side, and unite into the vena magna
Galeni, which joins the straight sinus. Each vena Galeni is
formed by the union of the choroid vein and the vena corporis
striati, and is joined by the basilar and other small veins, while
the vena magna receives tributaries from the occipital lobes
of each side and from the upper surface of the cerebellum.

The cerebellar veins are divided into two sets, the superior
and the deep.

The superior join the straight sinus and the vena magna
internally, and the superior petrosal and lateral sinuses exter-
nally.

The wferior enter the inferior petrosal, lateral, and occipital
sinuses along with branches from the medulla and pons.

1. The Cranial Sinuses.—The superior longitudinal sinus is
contained in the upper border of the falx cerebri, and extends
from the crista galli to the torcular Herophili. Its section is
triangular, and its cavity is crossed by several fibrous bands,
the chord Willisii, and contains some Pacchionian bodies.
It grooves the frontal, parietal, and occipital bones. In front
a small vein in the foramen cecum connects it with the nasal

‘veins, and through the parietal foramen it communicates with

the veins of the scalp. The superior cerebral veins open into
the sinus, looking forward contrary to the direction of the blood
current. At its termination it enlarges and becomes continuous
with the right (usually) or left lateral sinus. From this dilata-
tion (the torcular Herophili) a cross-branch passes to join the
straight sinus.

2. The inferior longitudinal sinus, in the lower border of the
falx cerebri, runs back to join the straight sinus.

3. The straight sinus continues the inferior longitudinal along
the line of junction of the falx with the tentorium backward,
and joins the lateral sinus opposite to that in which the superior
longitudinal ends. It receives the vena magna Galeni, some
superior cerebellar veins, and a cross-branch from the torcular
Herophili.

4. The lateral sinuses run in the attached margin of the ten-
torium from the internal occipital protuberance to the jugular
foramen, grooving, in order, the occipital, parietal, mastoid
portion of the temporal and the occipital a second time. Each

288 THE VASCULAR SYSTEMS

sinus receives the superior petrosal sinus and emissary veins
from the mastoid and posterior condylar foramina, as well as
some cerebellar, diploic, and posterior cerebral veins.

5. Occipital sinus, small, sometimes double, is contained in the
falx cerebelli, and opens into the torcular above and the lateral
sinus below by a branch on each side of the foramen magnum.
It receives some cerebellar veins and branches from the posterior
spinal veins.

qgittal SUHUS re
: AAA,
Falx cerebri,’

a

- ZZ
Z WW WS 3
\ WL XS YM = ~$ Vj
\\S We

Foramen cecum.

Me
nv" tr.
y

Torcular herophili.

Vertical section of the skull, showing the sinuses of the dura mater.

6. The cavernous sinuses, one on each side of the body of the
sphenoid, run from the sphenoidal fissure to the apex of the
petrous portion of the temporal, receiving the ophthalmic veins
in front and joining the petrosal sinuses behind. It receives the
sphenoparietal sinus, some inferior cerebral veins, and is joined
with the opposite vessel by the circular sinus.

7. The circular sinus consists of the anterior and _ posterior
intercavernous sinuses, which join at each end the cavernous
sinuses, thus surrounding the pituitary body.

8. The superior petrosal sinus runs from the cavernous sinus,
along the upper border of the petrous portion of the temporal,

Ta eT

een

Dura mater lining

THE VEINS OF THE HEAD AND NECK 289

to end in the lateral sinus at the fossa sigmoidea, It receives
the inferior cerebral, superior cerebellar, and some tympanic
veins.

9. The inferior petrosal, in the groove between the basilar
process and petrous portion, runs from the cavernous to join
the lateral sinus at the jugular foramen, completing the internal
jugular vein. (See under Internal Jugular Vein.) It receives
the auditory and some inferior cerebellar veins.

Fia, 48
Lining membrane of sinus.

Third nerve.

pituitary fossa.
fi Fourth nerve.

y First division of fifth nerve.
Sixth nerve.

Internal carotid.

Showing the relative position of the structures in the right cavernous sinus,
viewed from behind.

10. The transverse (basilar) sinus is a plexus in the dura mater
over the basilar process. It joins the anterior spinal veins below
and the two inferior petrosal sinuses laterally.

The ophthalmic veins are superior and inferior.

The superior passes back from the root of the nose with
the ophthalmic artery through the sphenoidal fissure to the
cavernous sinus.

The inferior runs back, near the floor of the orbit, to open into
the cavernous sinus, sometimes joining the superior.

The diploic veins run between the tables of the skull and open
into the dural sinuses or externally.

The emissary veins are small veins connecting the cranial
sinuses with the veins outside by means of foramina i in the bones.
These are the principal: one each—

(a) Through the mastoid foramen, from the lateral sinus to
the outermost occipital vein.

(b) Through the posterior condylar foramen, from the lateral
sinus to the cervical venous plexus.

19

290 THE VASCULAR SYSTEMS

(c) Through the parietal foramen, from the superior longitu-
dinal to the veins of the scalp.

(d) Through a foramen in the external occipital protuberance
to the occipital veins.

(e) Through the foramen ovale, from the cavernous to the
pterygoid plexus.

(f) Through the foramen lacerum medium, from the cavernous
sinus to the pharyngeal plexus.

(g) Through the carotid canal, a small plexus from the
cavernous sinus to the internal jugular.

(h) Through the anterior condylar foramen, a plexus from the
occipital sinus to the deep cervical veins.

THE VEINS OF THE UPPER EXTREMITY

The superficial veins commence from a plexus on the dorsum
of the hand mostly, but to some extent from the palm. They
comprise the following:

The ulnar, anterior and posterior, uniting above in the common
ulnar.

The radial vein is situated on the outer side, and the median
ascends mesially, receives a deep median vein, and divides at
the bend of the elbow into the median basilic and median
cephalic.

The median basilic joins the common ulnar to form the basilic.
The bicipital fascia separates it from the brachial artery.

The median cephalic crosses the external cutaneous nerve,
and joins the radial to form the cephalic.

The basilic runs along the inner side of the biceps, pierces the
fascia, and is continued upward into the axillary vein.

The cephalic runs along the outer side of the biceps, and be-
tween the pectoralis major and deltoid, piercing the costocora-
coid membrane to join the axillary vein below the clavicle.

The deep veins of the upper extremity are the venze comites.
They run one on each side of its artery from the digital to the
brachial arteries. The vene comites of the latter vessel, at
the lower border of the subscapularis muscle, empty into the
axillary vein.

The axillary vein begins where the venze comites of the brachial
artery and the basilic vein unite. It runs internal to the artery,

—-

THE VEINS OF THE TRUNK 291

and receives veins corresponding to its branches, as well as the
cephalic.

The subclavian vein is the Scnihvaatioh upward of the axillary,
and runs at a lower level than its artery, from which it is sepa-
rated by the phrenic nerve and scalenus anticus, to the inner
border of that muscle, to join the internal jugular, forming the
innominate. It receives the external jugular, and occasionally
the anterior. ,

THE VEINS OF THE TRUNK

The azygos veins are three in number.

I. The right, or vena azygos major, commences by the right
ascending lumbar vein. Ascending to the thorax through the
aortic opening and on the bodies of the dorsal vertebre to
the fourth, it arches over the root of the right lung and joins
the superior vena cava above the pericardium. It receives the
roght superior intercostal vein and the remaining right intercostal
veins save the first, the left azygos, the right bronchial, and
some esophageal, posterior mediastinal, and pericardiac veins.
Below it communicates with the common iliac by means of the
ascending lumbar.

II. The vena azygos minor inferior vein commences as the left
ascending lumbar, and ascends through the left crus and along
the spine to the ninth dorsal vertebra. It then crosses to the
right, behind the aorta, and joins the vena azygos major. It
receives the lower three or four intercostals and some mediastinal
veins.

III. The vena azygos minor superior vein is formed by the ©
fourth intercostal to the eighth inclusive, and joins the large
azygos. It receives the medvastinal tributaries, left bronchial
vein, and communicates above with the left superior intercostal.

The intercostal veins lie above the arteries.

The bronchial veins return part of the blood from the bron-
chial arteries. The right joins the vena azygos major; the
left, the left upper azygos.

The spinal venous system is made-up as follows: (a) The
dorsal spinal veins; (>) the ven basis vertebre; (c) the anterior
longitudinal spinal veins; (d) the posterior longitudinal spinal
veins, and (e) the veins of the cord, which run tortuously in pia
mater, one larger vein along the anterior fissure.

bo
leo)
bo

THE VASCULAR SYSTEMS

The Inferior Vena Cava

This large trunk arises at the fifth lumbar by the union of
the two common iliacs. It ascends to the right of the aorta,
grooves the posterior border of the liver, pierces the diaphragm,
is enclosed by the serous layer of the pericardium, and empties
into the right auricle. The Eustachian valve guards its orifice.
It receives the following tributaries:

(a) The lumbar, corresponding to the arteries.

(b) The spermatic forms within the spermatic cord a plexus,
the spermatic or pampiniform, which runs with the spermatic
artery through the inguinal canal, ending in several vessels
uniting into a single trunk. This vein, the spermatic, ascends
on the psoas behind the peritoneum, and joins the vena cava
on the right, the renal vein on the left side.

In the female its analogue, the ovarian vein, forms the pam-
piniform plexus in the broad ligament and runs with the artery.

(c) The renal veins run from the hilus of the kidney, in front
of the arteries, to join the vena cava at a right angle. The
left is longer and crosses the aorta. This vein receives some
small suprarenal branches and also the spermatic and supra-
renal veins.

(d) The suprarenal run from the suprarenal bodies to the
vena cava on the right, the renal on the left side.

(e) The inferior phrenic.

(f) The hepatic veins, two or three, join the vena cava at
the groove in the liver through which the latter passes.

The common iliac veins are formed by the junction of the
external and internal iliacs; they run from the base of the
sacrum to the upper part of the fifth lumbar vertebra, and
unite to form the inferior vena cava. The right is the shorter,
and is at first behind, later to the right, of its artery, while
the left is internal to its own artery, then behind the right
iliac artery. The common iliacs receive the following tribu-
taries:

The iliolumbar.

The two middle sacral, one on each side of the artery, anasto-
mose with the lateral sacral and hemorrhoidal veins, and unite
into a single vessel which joins the left common iliac vein,

THE VEINS OF THE LOWER EXTREMITY 293

THE VEINS OF THE LOWER EXTREMITY

The superficial veins begin on the dorsum of the foot in a
plexus which receives the digital veins, and forms an arch
from which emerge the internal or long and the external or
short saphenous veins.

The long (internal) saphenous, from the inner part of the
plexus, runs in front of the inner malleolus, along with the
long saphenous nerve, behind the inner border of the tibia
and condyle of the femur; thence up along the anterointernal
part of the thigh to join the femoral vein at the saphenous
opening. It communicates with the deep plantar, both tibial,
and the femoral veins, and receives superficial plantar and
cutaneous tributaries, and the swperficial circumflex iliac,
epigastric, and eaternal pudic veins.

The short (external) saphenous vein ascends behind the outer
malleolus, and external to the tendo Achillis, with the external
saphenous nerve, and pierces the deep fascia in the popliteal
space to join the popliteal vein. It receives branches from the
heel and back of the leg and from the deep veins and the long
saphenous. '

The deep veins are the vene comites of the arteries. The
posterior tibial veins receive the peroneal, and join the anterior
tibial to form the popliteal. This vessel then ascends, crossing
superficial to the artery, from the inner to the outer side, and
becomes the femoral at the adductor opening. It receives
the external saphenous and veins corresponding to the arterial —
branches.

The femoral vein accompanies the artery, and becomes the
external iliac at Poupart’s ligament. It is at first outside,
then behind, and at its termination internal to the artery. It
receives, in its lower part, veins corresponding to the branches
of the superficial femoral artery; the long saphenous, and the
profunda vein. ‘The latter is formed by the union of the vene
comites of the offsets of the profunda artery.

The external iliac runs to join the internal iliac near the
lumbosacral articulation, being at first internal to, later behind,
the artery. It receives the deep circumflex iliac, the deep epi-
gastric, and a pubic vein.

294 THE VASCULAR SYSTEMS

THE VEINS OF THE PELVIS

The internal iliac vein accompanies the artery, lying behind
and to its inner side, to join the external at the base of the
sacrum, forming the common iliac. Its tributaries correspond
to the branches of the artery in a general way. Thus it receives
the following tributaries:

The gluteal, sciatic, and the obturator; the lateral sacral,
which form a plexus on the sacrum and open into the internal
iliac at several points; the znternal pudic, which receives branches
corresponding to the perineal branches of the artery and com-
mences as the vein of the corpus cavernosum.

The dorsal vein of the penis, at first two veins, these uniting
into one, which runs back between the two dorsal arteries
in a median groove, passes below the subpubic ligament and
divides into two veins, joining each side of the prostatic plexus,
and each division communicating with the obturator and
pudic veins of each side.

The visceral veins are larger than the arteries, and communi-
cate freely with one another, so as to form a series of plexuses,
as follows:

The prostatic plexus, continuous above with the vesical
plexus, is formed by the dorsal vein of the penis and branches
from the prostate and its vicinity. It communicates with the
radicles of the pudic vein. This plexus has its analogue in
~ the female around the urethra, which receives the dorsal vein
* of the clitoris.

The vesical plexus extends over the body and base of the
bladder, and communicates with the prostatic and hemorrhoidal
plexuses; vaginal in the female.

The hemorrhoidal plexus, in the wall of the lower rectum,
beneath the mucous coat, sends out superior, middle, and
inferior hemorrhoidal veins, which follow the corresponding
arteries, and communicate freely with the other plexuses.

The vaginal plexus surrounds the lower part of the vagina,
and communicates with the vesical and hemorrhoidal plexuses,
and the uterine plexus empties into the ovarian vein.

ae <>.

)
7
q

THE PORTAL SYSTEM 295

THE PORTAL SYSTEM

The portal system consists of the veins which drain the gall-
bladder, stomach, spleen, pancreas, duodenum, jejenum, ileum,
cecum, colon, and upper portion of the rectum; these tributaries
usually bear the same names as the arteries, which they accom-
pany. However, the portal vein is found, directly, by the
splenic and superior mesenteric veins joining behind the neck
of the pancreas, also the gastric, pyloric, cystic, and parum-
bilical veins open into it before reaching the transverse fissure
of the liver.

The portal vein, 3 inches long, ascends behind the duodenum
and between the layers of the lesser omentum. Here it runs
behind the hepatic artery and bile duct. Accompanied by the
hepatic plexus of nerves and lymphatics, all enclosed in Glisson’s
capsule, it then enters the transverse fissure, forming near
the right end the “sinus,” and divides into: A right branch,
to the right lobe, which distributes branches entering the
hepatic substance with the hepatic arterial branches and ducts;
and a left branch distributed like the right.

The superior mesenteric, corresponding to the artery of the
same name, receiving also the right gastroepiploic vein, besides
branches accompanying those of the artery. It joins the
splenic vein. :

The splenic arises by five or six vessels uniting after leaving
the hilum, and runs to the right below the artery, joining the
above at a right angle to form the vena porte. It receives
the vasa brevia, left gastroepiploic, and pancreatic branches, and
the inferior mesenteric vein.

The inferior mesenteric vein corresponds in branches and
course to the artery, and empties into the angle of junction
of the two preceding.

The gastric vein accompanies the gastric artery and runs
along the lesser curvature of the stomach between the two
layers of the gastrohepatic omentum, it receives some esopha-
geal veins near the esophageal end of the stomach and then
runs from left to right posterior to the lesser peritoneal cavity
to open into the portal vein.

The pyloric runs with the pyloric branch of the hepatic
artery, and joins the vena porte.

296: THE VASCULAR SYSTEMS

The cystic vein drains the gall-bladder and accompanies the
gall-duct to open into the right branch of the portal vein.

The parumbilical veins are small veins found in the urachus
and ligamentum teres, which establish an anastomosis between
the anterior abdominal wall and the portal and iliac veins.
They are best seen from the umbilicus upward, running along
the round ligament, then between the layers of the falciform
ligament, to end in the left branch of the portal vein.

THE ABSORBENT OR LYMPHATIC SYSTEM

The absorbent system consists of vessels resembling thin-
walled veins, the lymphatics, interrupted at intervals by the
lymphatic nodes. The lymphatics of the alimentary canal
are called lacteals. All these vessels converge to two principal
trunks, the thoracic duct and the right lymphatic duct, which
open into the large veins at the root of the neck.

The Thoracic Duct

The thoracic duct is the common trunk of all the lymphatic
vessels of the body, excepting those which drain the right
side of the head and neck, the right upper extremity, the right
lung, right side of the heart, and part of the convex surface
of the liver. It is from 15 to 18 inches in length, in the adult,
and begins as the receptaculum chyli. The duct extends from
the second lumbar vertebra to the root of the neck, where it
empties into the angle of junction of the left internal jugular and
subclavian veins. It is placed in front of the dorsal vertebree
and passes to the thorax through the aortic opening between the
aorta and vena azygos major. It then runs upward toward the
left, behind the arch of the aorta (at the fourth dorsal vertebra),
then between the esophagus and left subclavian artery, and
at the seventh cervical vertebra it arches over the pleura to ~
join the angle of union between the left subclavian and internal
jugular veins.

The right lymphatic duct collects the lymph from the parts
just mentioned above. It is only one-half inch or less in length,
and empties on the right side, at a point corresponding to that
where the thoracic duct empties on the left side.

THE THORACIC DUCT

Thoracic duct, azygos and intercostal veins.

297

UPPER END OF
THORACIC DUCT

(Testut.)

298 THE VASCULAR SYSTEMS

THE LYMPHATIC VESSELS AND NODES OF THE LOWER
EXTREMITY

The lymphatics of the lower limb are arranged in a super-
ficial and a deep set. The former open, in general, into the
superficial inguinal nodes; the latter into the deep inguinal
nodes. The superficial follow, in a general way, the course
of the long saphenous vein; the deep accompany the deep
bloodvessels, and in the leg enter the popliteal nodes; in the
gluteal and adductor region some enter the internal iliac nodes.

The superficial lymphatics of the lower part of the trunk
also join the superficial inguinal nodes. The superficial lymph-
atics of the penis enter the superior set of superficial inguinal
nodes; the deep run under the pubic arch to join the internal
iliac nodes. ‘The superficial lymphatics of the scrotum join
the superficial inguinal nodes. In the female external genitalia
a similar disposition obtains.

The superficial inguinal nodes, eight or ten, consist of a
superior or oblique set in the line of Poupart’s ligament, and
an inferior or vertical set lying around the upper part of the
saphenous vein. Efferent vessels join the deep inguinal and
external iliac nodes.

The four or five popliteal nodes surround the vessels, and
receive the deep and some superficial absorbents of the leg.

The deep inguinal glands lie around the femoral vessels;
one at the crural ring is constant.

THE LYMPHATIC VESSELS AND NODES OF THE PELVIS
AND ABDOMEN

These include the following:
Six or more external zliac nodes surround these vessels.

Numerous internal iliac nodes, and sacral glands on the ©

face of the sacrum.

The lymphatics of the bladder enter the internal iliac nodes
with the prostatic branches.

The lymphatics of the uterus, with those of the vagina, to
the internal iliac nodes.

The lymphatics of the rectum enter the sacral node.

LYMPHATIC VESSELS AND NODES OF ABDOMEN 299

The lumbar nodes comprise a middle and two lateral groups.
The former lie around the aorta and vena cava, the latter
beneath the psoas. Most of the efferent vessels join to form,
on each side, the lumbar lymphatic trunk, which runs into
beginning of the thoracic duct.

The lymphatics of the kidney, deep and superficial, join the
middle lumbar set after receiving the suprarenal lymphatics
and some from the ureter.

The lymphatics from the testicles, superficial and deep,
through the inguinal canal, in the cord, to join the lumbar
nodes.

The deep lymphatics of the abdominal wall receive others
from the spinal canal and muscles, and join the lateral lumbar
nodes. At the upper part they enter the sternal nodes.

About one hundred and fifty mesenteric nodes lie between
the layers of the mesentery in the arterial arches and around
the superior mesenteric artery.

The lacteals form one plexus beneath the mucous membrane
and one in the muscular coat, and leave the intestine at the
attachment of the mesentery to enter the mesenteric nodes,
and, emerging, join the efferent vessels from the celiac nodes
and form a single trunk. This intestinal lymphatic trunk
joins the thoracic duct.

Sixteen to twenty celzac nodes, around the celiac axis and
adjacent aorta, receive the lymphatics from the stomach,
spleen, pancreas, and a large part of the liver.

The lymphatics of the stomach traverse the gastric nodes
at the greater and lesser curvature and join the celiac nodes.
From the left end they join the splenic lymphatics.

The lymphatics of the spleen, superficial and deep, enter
the celiac nodes after receiving the pancreatic vessels.

The lymphatics of the liver are superficial and deep. The |
superficial on the upper surface are arranged in four groups:
(1) The mesial, from both lobes, run through the diaphragm
to the anterior mediastinal nodes; (2) the lateral of each lobe to
the celiac nodes; (3) the posterior, through the diaphragm to the
nodes around the inferior vena cava; (4) an anterior group
joins those on the inferior surface.

The superficial lymphatics on the lower surface run to the
transverse fissure, for the most part, to join with the deep
lymphatics. Some join the gastric lymphatics.

300 THE VASCULAR SYSTEMS

The deep hepatic lymphatics accompany the portal and
hepatic veins. The former join the other vessels from the
under surface at the transverse fissure, and traverse some
small hepatic nodes to join the celiac nodes. Those accom-
panying the hepatic veins form five or six trunks piercing
the diaphragm, and join the glands around the vena cava.

THE LYMPHATIC SYSTEM OF THE THORAX

This is composed of six to ten internal mammary or sternal
nodes along the course of the vessels.

Along the line of the heads of the ribs, on each side of the
spine, are the intercostal nodes. ‘They send vessels to both
the thoracic and right lymphatic ducts.

Several anterior mediastinal nodes lie between the sternum
and the pericardium.

Eight or ten superior mediastinal or cardiac nodes, around
the great vessels, receive the lymphatics of the heart and
thymus gland.

Numerous bronchial nodes, between the bronchi and along
their primary divisions, receive the lymphatics of the lung.
They deepen in color as age advances.

Ten or twelve posterior mediastinal nodes, along the esophagus
and aorta.

The deep lymphatics of the chest wall are an anterior set,
in the intercostal spaces, joining the internal mammary nodes,
and a posterior or intercostal set, along with the intercostal
vessels, joining the intercostal nodes.

The cardiac lymphatics run toward the base of the heart,
and form a trunk on each side. Of these, the right enters a
node above the aortic arch—the left, the nodes behind that
vessel.

The pulmonary lymphatics, superficial and deep, end in the
bronchial nodes.

The esophageal lymphatics form a plexus between the muscular
and mucous coats and join the posterior mediastinal nodes.

The thymic lymphatics enter the superior mediastinal nodes.

ABSORBENT SYSTEM OF THE HEAD AND NECK 3801

THE LYMPHATICS OF THE UPPER LIMB

These consist of a superficial and a deep set, both converging
to the axillary glands. The former have a somewhat similar
distribution to that of the veins, some entering the infracla-
vicular glands; the latter correspond to the deep bloodvessels,
communicate with the superficial lymphatics near the wrist,
traverse the glands around the brachial artery near the elbow,
and end in the axillary.

The axillary nodes are ten to twelve in number, and lie
mostly along the axillary vessels; but some, the pectoral, sub-
scapular, and infraclavicular, occupy the positions indicated
by their names. The efferent vessels from all these glands
run along the subclavian vein, and may unite into a single
axillary lymphatic trunk. They finally reach the thoracic
or right lymphatic duct respectively; or they may enter the
subclavian vein directly.

The superficial lymphatics of the chest drain the bet phi from
the pectoral muscles, skin, and mamma, and together with
some superficial abdominal lymphatics enter the axillary glands.
Those from the back converge from all parts to reach the axillary
glands.

THE ABSORBENT SYSTEM OF THE HEAD AND NECK

This consists of the following:

One or more suboccipital nodes on the complexus send
branches to the cervical nodes.

Several mastoid nodes over the insertion of the sternomastoid.

Some parotid nodes, beneath the parotid fascia and embedded
in the node, receive superficial temporal lymphatics, and send
branches to the submaxillary and superficial cervical nodes.

The internal maxillary nodes, deep beneath the ramus of the
jaw, around the artery and side of the pharynx, with branches
to the deep cervical nodes.

Kight or ten submaxillary nodes beneath the base of the
jaw drain the lymph from the floor of the mouth and the
salivary glands and from the parotid lymphatic nodes. The
efferent vessels join the superficial and deep cervical nodes.

i ae

302 THE VASCULAR SYSTEMS

The superficial cervical nodes, four to six, along the external
jugular beneath the platysma, receive the auricular lymphatics,
efferent trunks from the suboccipital, mastoid, and some
from the parotid and submaxillary nodes. The efferent vessels
enter the inferior deep cervical nodes.

The deep cernmcal, twenty to thirty, consist of an upper and
a lower set. The former run along the internal jugular vein;
the latter around the lower part of the vein and into the supra-
clavicular fossa, and join the superior mediastinal and axillary
nodes; they receive afferent trunks from all the other cervical
nodes and the lymphatics of the lower part of the neck, and
send out branches which unite into a jugular lymphatic trunk.
This trunk then joins the thoracic or right lymphatic duct,
or may open into a large vein. )

The lymphatics of the scalp join the suboccipital, mastoid,
and parotid nodes.

The lymphatics of the face follow the course of the facial
vein to the submaxillary nodes, but there are others externally
which join the parotid nodes. The deep lymphatics from the
orbit, nasal cavity, palate, and cheek join the internal maxillary
nodes.

The cranial lymphatics form a network in the pia mater,
and run along the internal carotid, vertebral, and internal
jugular veins to the deep cervical nodes.

The lingual lymphatics run with the ranine vein, traverse
several lingual nodes, and join the upper deep cervical nodes.
‘One or two join the submaxillary.

The retropharyngeal nodes are found in the buccopharyngeal
fascia behind the pharynx and in front of the arch of the atlas,
however, separated from the latter by the rectus capitis anticus
major. They drain the nasal fosse, the nasopharynx, and the
Eustachian tube, as far as the tympanum; then their efferents
pass to the upper set of deep cervical modes.

QUESTIONS ON ANGIOLOGY

Which auricular appendix is the more anterior?
Which ventricle forms the apex of the heart?
Which surface of the heart rests on the diaphragm?

THE ARTERIES

Of what are the bronchial arteries branches?

Of what are the coronary arteries branches?

Name in order the branches of the transverse aortic arch.

How do the subclavians differ from each other?

Of what are the vertebral arteries branches?

Opposite what point does the common carotid divide?

nee relation does the external carotid bear to the internal in the
neck. ;

Of what’is the lingual artery a branch, and where does it come off?

Describe precisely the course and relations of the lingual artery.

Name the branches of the inferior thyroid artery.

Of what is the posterior scapular artery a branch?

What structure loops around the occipital close to its origin?

Describe the relation of the internal maxillary artery to the external
pterygoid muscle.

How is the basilar artery formed?

Describe the circle of Willis.

Describe the ophthalmic artery and its branches.

How is the facial artery situated with reference to its vein?

Where can the facial artery be readily felt and compressed?

Describe the origin and course of the internal mammary arteries.

Where does the axillary artery begin and end?

Which division of the axillary artery is in relation to the cords of the
brachial plexus, and what is that relation?

Describe the axillary space, giving location and direction of apex
and base, and describe its walls.
* Describe the relation of the lower division of the axillary artery and
the brachial artery to the median nerve.

What structures does the radial artery lie upon above the wrist?

What separates the radial artery from the skin?

What separates the ulnar artery from the skin?

Of what is the common interosseous artery a branch?

To which side of the radial artery is nerve of same name?

To which side of the ulnar artery is the nerve of that name?

Of what artery is the superficial palmar arch principally formed?

Locate both palmar arches on your own hand.

Of what are the superior intercostal arteries branches?

To which side of the external abdominal ring is the deep epigastric
artery!

Opposite what point of the anterior abdominal wall does the aorta
bifurcate?

What position does the hepatic artery occupy in the lesser omentum?

Where does the common femoral artery end?

Of what are the circumflex arteries branches?

State the boundaries of Scarpa’s triangle, and give in order the
muscles in its floor.

What muscles enter into the formation of Hunter’s canal?

What muscles is the profunda femoris in relation with?

What arteries form the crucial anastomosis?

What are the branches of the popliteal artery?

Is the anterior tibial artery in direct relation with the interosseous
membrane?

How does the anterior tibial artery get to an anterior position, and
what ASemOn does it bear, in its upper part, to the anterior tibial
nerve?

Is the posterior tibial artery on the interosseous membrane; if not,
where is it?

Give the courses and relations of the internal and external plantar
arteries.

THE VEINS

How many pulmonary veins are there?

What forms the superior vena cava?

What are large veins in the dura mater called?

Where and how is the internal jugular vein formed?

How is the axillary vein formed?

Where does the cephalic vein empty?

Where does the inferior vena cava enter the pericardium, and how
long a portion of it is above the diaphragm?

Into what does the left spermatic vein empty?
Mali is the internal saphenous found in the leg? Where in the
thig

To which side of the common femoral artery is its vein?

What forms the portal vein?

How long is the portal vein, and what is its position in the lesser
omentum?

THE LYMPHATICS

Where is the thoracic duct formed?

How does it enter the thorax?

What are its relations in the thorax, and where does it empty?

Is there anything on the right side to at all correspond to the thoracic
duct?

Name the places where the lymphatic nodes principally appear in

groups.

PART V

NEUROLOGY, OR THE ANATOMY OF THE
NERVOUS SYSTEM

THE CEREBROSPINAL AXIS

THE SPINAL CORD

THE spinal cord is enclosed by three membranes, the dura,
arachnoid, and pia.

The spinal dura is a loose fibrous envelope which is attached
closely to the margin of the foramen magnum above, but
only loosely to the circumference of the vertebral canal below
blending with the periosteum on the dorsum of the coccyx,
where it is called the coccygeal ligament. Its inner surface
is covered by a layer of epithelium, and it presents on each
side a series of double orifices for the exits of the anterior
and posterior roots of the spinal nerves. The dura is pro-
longed on to these nerves as a tubular investment. |

The arachnoid is a very delicate membrane which invests
the cord between the dura and pia. It is continuous above
with the cerebral arachnoid, and is connected by meshes of
fibrous tissue with the pia, and to some extent also with the
dura, from which it is separated by the subdural space. The
subarachnoid space contains the subarachnoid fluid, which
separates it from the pia mater. This space, by means of the
foramen of Magendie, is continuous with the cavity of the
ventricles of the brain.

The pia is closely connected to the cord, and sends a pro-
longation down into the anterior, and a very delicate process

004 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

into the posterior median fissure. It ensheathes the spinal
nerves, and ends below in the filum terminale, which joins the
dura at the upper limit of the sacral canal.

Along the anterior median surface of the pia runs a prominent
fibrous band, the linea splendens, and between the two nerve
roots on each side is a serrated band, the ligamentum denticu-
latum, the points of the serrations, about twenty on each side,
being attached to the dura between the pairs of nerve roots.

The spinal cord is about 18 to 20 inches long, weighs about
an ounce, and occupies about the upper two-thirds of the spinal
canal, viz., from the foramen magnum to the lower border
of the first lumbar vertebra. It ends in a narrow cord of gray
substance which runs in the midst of the filum terminale.

The enlargements of the spinal cord are two—an wpper or
cervical, extending from the third cervical to the first or second
thoracic vertebra, and a lower or lumbar, from the tenth thoracic
to about the first lumbar. These enlargements correspond
to the origin of the nerves which supply the upper and lower
extremities respectively. The surface of the cord presents
several fissures, which will now be described.

The fissures of the spinal cord are an anterior and a posterior
median, and laterally on each side are several grooves called
fissures.

The anterior median fissure extends through about one-
third the thickness of the cord, as far as the anterior white
commissure, and contains a fold of the pia.

The posterior median fissure extends about halfway through
its substance to reach the posterior or gray commissure. It
is not a real fissure, being filled up by connective tissue.

The anterolateral fissure is merely the line of origin of the
anterior nerve roots, while the posterolateral is in reality a
groove, and runs along the line of origin of the posterior nerve
roots.

Lastly, a slight groove, the posterior paramedian fissure,
marks off the posterior intermediate column on either side of
the posterior median fissure.

The columns of the spinal cord are divisions made by these
fissures, three on each side.

The anterolateral column, between the anterior median and
posterolateral fissures. The posterior column, between the
posterolateral and posterior median fissures, becomes divided,

THE SPINAL CORD 305

by the slight groove above mentioned, into the posterior lateral
and posterior median columns.

The columns of the spinal cord are divided into three chief
columns or funiculi: the ventral, dorsal, and lateral.

The ventral is subdivided into the following tracts: Descend-
ing—direct pyramidal tract, sulcomarginal tract, ventral ves-
tibulospinal tract (Léwenthal’s; anterior cerebellospinal tract) ;
associating—association axones between spinal centres and
several cranial nerve nuclei, fasciculus ventralis proprius.

Location of the tracts as regards their distribution within
the cord: the direct pyramidal tract extends through the
cervical and lower portion of the thoracic, and rarely as low
as the lumbar region of the cord; the sulcomarginal tract is
found chiefly in the cervical portion of the cord; the ventral
vestibulospinal fibers terminate about the ventral horn cells,
and have been traced as low as the sacral region.

The dorsal column is subdivided into the following tracts:
Ascending—fasciculus gracilis, or tract of Goll, the fasciculus
cuneatus, or tract of Burdach; descending—the comma tract
of Schultze, the median oval tract of Flechsig; associating—
the fasciculus: dorsalis proprius, dorsal cornucommissural
tract, septomarginal tract of Bruce, the fasciculus marginalis
of Spitzka and Lissauer, the latter is usually described as
belonging to the lateral column, but functionally it is more
intimately related to the sensor neurone system of the dorsal
column.

The lateral column is subdivided into the following tracts:
Ascending—dorsolateral spinocerebellar tract of Flechsig,
superficial ventrolateral spinocerebellar tract of Gowers,
spinothalamic tract, spinomesencephalic tract; descending—
crossed pyramidal tract, rubrospinal tract, cerebrospinal
tract (Marchi and Léwenthal), lateral. vestibulospinal tract,
olivospinal tract of Helwig; associating—fasciculus lateralis
proprius.

The posterior cornu is constricted at its base (cervix cornu),
and then expands (caput cornu) before narrowing to its extremity
(apex cornu). Around the latter the neuroglia forms the sub-
stantia gelatinosa. /

The gray matter of the cord consists of nerve fibers, nerve
cells, and connective tissue (neuroglia). The nerve cells are
for the most part arranged in columns. Of these columns,

20

306 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

one, at the inner side of the cervix cornu, is called the posterior
vesicular column of Lockhart Clarke; a second, at the con-
cavity of the gray matter, the tractus intermediolateralis;
and a third is found along the anterior part of the anterior
cornu.

THE BRAIN (ENCEPHALON)

The encephalon, or brain, is that part of the cerebrospinal
axis which, with its membranes, is contained in the cranium.
It is composed of the cerebrum, cerebellum, pons Varolii, and
medulla oblongata.

The membranes of the brain are the dura, the pia, and the
arachnoid.

The dura is similar in structure to the dura of the cord, but
differs from it in being closely attached to the cranial bones,
forming, in fact, their inner periosteum. It is continuous
with that of the cord at the foramen magnum, and with the
external periosteum of the cranial bones by means of its pro-
longations into the many foramina. It sends in various processes
to support and separate the different parts of the brain, and
its layers separate to form the cranial sinuses. In the vicinity
of the superior longitudinal sinus are to be found, on its outer
surface, several glandule Pacchionii. They may also be seen
on its inner surface and within the sinus, as well as on the
pia mater.

The processes include the falces cerebri et cerebelli and the
tentorium cerebelli.

The falx cerebri separates the cerebral hemispheres. In
front it is narrow, becoming broader behind. Its upper convex
margin is attached to the vault of the cranium from the crista
galli in front to the internal occipital protuberance behind.
Its lower margin is free and concave anteriorly, while it is
attached posteriorly to the upper surface of the tentorium.
Above it lodges the superior, below the inferior longitudinal
sinus and part of the straight sinus.

The falx cerebelli is triangular, and separates, inferiorly,
the lateral cerebellar lobes. It is attached above to the under
and posterior part of the tentorium, behind to the internal
occipital crest, below the torcular Herophili, and to the foramen
magnum, where it often divides into two parts, which are
attached to its margins.

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THE MEDULLA OBLONGATA 307

The tentoriwm covers the upper surface of the cerebellum.
Its posterior border, where it is attached to the. transverse
ridges of the occipital bone, encloses the lateral sinuses; along
the superior border of the petrous portion it forms the superior
petrosal sinus, and at the junction of its upper surface with
the falx cerebri is the straight sinus. Besides these points,
it is attached to the anterior and posterior clinoid processes.
Its anterior concave edge is free, and with the dorsum selle
forms a large oval opening. This is called the incisura tentorii
and transmits the mesencephalon.

The pia is a very vascular delicate membrane which dips
into the sulci and forms the various choroid plexuses and also
the velum of the third ventricle. The vessels of the brain
run in the pia mater before entering the brain.

The arachnoid is a similar membrane to that of the cord,
and is separated, as in the cord, by the subarachnoid fluid
from the pia. It does not dip into the sulci. In front it leaves
a space between it and the pia mater, viz., along the pons and
interpeduncular region, the anterior subarachnoidean space;
and behind, between the medulla and the cerebellum, is a
second interval called the posterior subarachnoidean space.
Both are connected with the ventricles of the brain by the
foramen of Magendie in the pia mater covering the fourth
ventricle.

The subarachnoid fluid is a clear alkaline fluid containing
1.5 per cent. of solids, animal and mineral.

Parts Derived from the Hind-brain (Rhombencephalon)

The hind-brain and the parts included therein—the medulla
oblongata, the pons, and the cerebellum.

The Medulla Oblongata

The medulla oblongata is a pyramidal body, 2 to 1 inch
long, along its ventral surface, and 2 inch thick. Its larger
extremity is continuous with the pons; its smaller extremity,
directed downward and backward, blends with the spinal

-cord. The anterior surface lies on the basilar groove of the

occipital bone.

308 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

In front and behind it is marked by the continuation of
the anterior and posterior median fissures of the cord, the
former, with its process of pia mater, ending in a cul-de-sac
just below the pons, the foramen cecum. The posterior expands
into the fourth ventricle.

Each lateral half of the medulla is divided into areas.

The areas of the medulla oblongata are: (1) Ventral area; con-
taining the pyramid. (2) Lateral area; containing the lateral
tract olive. (3) Dorsal area; containing the funiculus gracilis,
funiculus cuneatus, funiculus lateralis and tuberculum cinereum.
(Gray.)

The restiform body succeeds the gracile and cuneate nuclei
in the dorsolateral part of the medulla oblongata. Its fibers
converge from various sources and ultimately enter the cere-
bellum as its inferior peduncle. (Gray.)

The Decussation of the Pyramids. It is a term applied to
the interlacing bundles seen on the ventral aspect of the medulla,
at the junction of the medulla and the spinal cord. Ninety
per cent. of the fibers cross the median line in this decussation
to continue as the crossed pyramidal tract.

SUMMARY OF THE GRAY MASSES IN THE MEDULLA
OBLONGATA

Central tubular gray (in “closed” part).
Gray floor of fourth ventricle (in “open”’ part).
Gelatinosa Rolandi, or gliosa.

Nucleus funiculi gracilis.

Nucleus funiculi cuneatus.

Nucleus funiculi cuneati accessorius.
Nucleus lateralis.

Nucleus olivarius inferior.

Nucleus olivarius accessorius dorsalis.
Nucleus olivarius accessorius medialis.
Nucleus arcuatis.

Nucleus nervi hypoglossi.

Nucleus intercalatus.

Nucleus postremus.

Nucleus vagi (ala cinerez).

Nucleus vestibularis (spinal division).

THE PONS 309

Nucleus funiculi teretis.

Nucleus ambiguus.

Nucleus tractus solitarii.

Nucleus tractus spinalis nervi trigemini.
Formatio reticularis. (Gray.)

The Pons

The pons is a white mass on the anterior aspect of the brain
stem placed between the medulla oblongata and the crura
cerebri. It is convex from side to side, containing mostly
transverse and longitudinal fibers. The transverse’ fibers
are collected into rounded bundles, to continue as the middle
peduncles into the white substance of the corresponding cere-
bellar hemispheres. ‘The middle peduncles are commissural
paths consisting of axones coursing in opposite directions
connecting the nuclei pontis with the cerebellum; then some
axones pass into the opposite middle peduncle, forming un-
interrupted commissural systems; again, a few fibers communi-
cate with nuclei in the brain stem, notably the oculomotor,
trochlear, and abducent cranial nerves.

The basilar surface is in relation with the basilar process
of the occipital and the dorsum selle of the sphenoid. In a
shallow central groove (basilar groove) is lodged the basilar
artery. The large sensor and small motor root of the trigeminal
nerve pierces the prelateral portion of the pons, near its anterior
pontile border; the abducent nerve passes forward and upward
around the posterior pontile border (prepyramidal part); the
facial and acoustic nerves arise further external in the latter
border.

The pars dorsalis pontis, or tegmental part. The dorsal
surface is continuous with that of the oblongatal ventricular
surface, and will be described under the description of the
rhomboid fossa or the floor of the fourth ventricle.

THE SUMMARY OF THE GRAY MASSES IN THE Pars DoRSALIS
PonrtIs

Nucleus of abducent nerve.
Nucleus of facial nerve.

310 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

Afferent and efferent nuclei of trigeminal nerve.

Nucleus of spinal root of trigeminal nerve.

Nuclei of Acoustic Nerve.—Cochlear division: Dorsal
nucleus; ventral nucleus. Vestibular division: Medial nucleus;
lateral nucleus; superior nucleus.

Superior olivary nucleus.

Nucleus of trapezium.

Reticular ganglionic formation.

Nucleus incertus.

Nucleus of lateral lemniscus. (Gray.)

The Cerebellum

The cerebellum is the largest portion of the hind-brain.
It lies in the posterior fossa of the skull, separated from the
occipital lobes of the cerebrum by the tentorium cerebelli.
It is behind the pons and medulla oblongata, connected with
the former through the middle peduncles, and partly embracing
the latter; and connected with the restiform body by means
of the inferior peduncles; the superior peduncles contain fibers
which pass from the cerebellum to the tegmentum of the mid-
brain, ventrad of the inferior corpora quadrigemina, the latter
bundle of fibers pass to the red nucleus of the opposite side,
some continue to enter the thalamus.

The cerebellum is divided into a medial segment, the vermis,
or worm; two lateral hemispheres; a ventral and dorsal notch;
and a superior and inferior surface; and is subdivided into
lobes and fissures.

The lobes and fissures seen on the superior surface of the
vermis or prevermis are from before backward, alternately;
lingula, precentral fissure; lobulus centralis, postcentral fissure;
culmen monticuli, preclival fissure; clivus monticuli, post-
clival fissure; folium cacuminis, peduncular fissure. Inferior
surface of vermis; tuber vermis, postpyramidal fissure; pyramis,
prepyramidal fissure; uvula, postnodular fissure; nodulus.
The hemispheres present on their superior and inferior surfaces
the same fissures as mentioned under the vermis. The lobes
are, the superior surface from before backward; the vincula
lingulze, ala lobuli centralis, anterior crescentic, posterior cres-
centic, superior semilunar; inferior surface, inferior semilunar
and gracile lobes are lateral prolongations of the tuber vermis;

THE FOURTH VENTRICLE 311

the postgracile fissure separates the former two lobes, which
are called sometimes the posterior inferior lobules; they com-
prise at least two-thirds of the inferior surface of the cerebellum.
The biventral, tonsilla (amygdala), and flocculus lobes are
found on the inferior surface of the cerebellar hemispheres.

The ventral notch is in relation with the brain stem (teg-
mental part of the pons and corpora quadrigemina); the
dorsal notch is smaller and narrower and lodges the falx cere-
belli, which separates the hemispheres as they project beyond
the inferior vermis.

The arbor vite is the name given to the arrangement of the
white substance of the cerebellum, seen on a median section.
The cerebellum weighs 5.8 ounces in the male, and 5.4 ounces
in the female. The proportion between the cerebellum and
cerebrum is | to 7.5 in the adult; 1 to 8.5 among eminent men;
1 to 20 in the newborn. (Gray.)

SUMMARY OF THE GRAY MASSES IN THE CEREBELLUM

Embedded in the white substance are the following—four
on each side:

Dentate nucleus or dentatum.

Nucleus emboliformis or embolus.

Nucleus globosus or globulus.

Nucleus fastigi or fastigium. (Gray.)

The Fourth Ventricle

The fourth ventricle (or fossa rhomboidea) is an irregularly
pyramidal shaped cavity, with a lozenge-shaped base and
ridge-like apex; found between the medulla oblongata and
the pars dorsalis pontis in front and the cerebellum behind.
It is divided into a roof and a floor. The roof is formed by
the valvula (of Vieussens), the superior peduncles, tela choroidea,
ventricula quarti, and fastigium of the cerebellum. ‘The floor
is divided into a larger cephalic (pars superior), and a
smaller caudal (pars inferior) triangle by white, transverse
strie, the strie acustice, termed the pars intermedia by His.
The pars superior is separated into two halves by a longitudinal
groove, the fovea mediana. On each side of the fovea mediana,

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PARTS DERIVED FROM THE MID-BRAIN 313

above and external to the latter and the eminentia abducentis
is the fovea and area trigemini; the area vestibularis is the
smooth surfaces above and below the striz acusticz and laterad
of the lateral furrow, connecting the .superior and inferior
fovea. The pars inferior presents in the centre a longitudinal
furrow dividing it into two small triangles, with their bases
placed cephalad. They present just adjacent to the furrow
and below the striz acustice the eminentia hypoglossi and
the nucleus intercalatus; external to and below the latter is a
depression, the fovea inferior, and below the fovea inferior
is an eminence, the trigonum vagi, or ala cinerea, which is sepa-
rated from the area postrema, by the funiculus separans.
The convergence of the median and lateral furrows at the
caudal apex of the rhomboidal fossa forms the calamus
scriptorius, which resembles an ancient writing reed or quill
pen (Gray); hence the name. Caudad the fourth ventricle is
continuous with the small central canal of the cord and post-
oblongata (in part); cephalad it communicates with the third
ventricle by means of the aqueduct, or mesocele. The fourth
ventricle has an opening through the tela choroidea, which
permits of communication with the subarachnoid space, and it
is called the foramen of Majendie; also, the extremities of the
lateral recesses permit of a tidal flow of the cerebrospinal
fluid, through the foramina of Luschka. The locus ceeruleus
is continued upward from the superior fovea and extends
well up into the aqueduct; it owes its color to the refraction
of the pigmented cells, the substantia ferruginea.

Parts Derived from the Mid-brain (Mesencephalon) —

The mid-brain and the parts included therein—the crura
cerebri, corpora quadrigemina, the internal geniculate bodies, and
the aqueduct (mesocele) and central aqueduct gray.

The crura cerebri are seen, after separating the temporal
lobes, as two white bundles, which emerge above the pons;
diverging, they pass forward and outward to the inner and
under part of each hemisphere; beneath the optic tract. Be-
tween them is seen the intercrural (interpeduncular or posterior
perforated space); near the inner border of each crura are the
roots of the motor oculi nerves passing forward from the sulcus
oculomotorius.

314. NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The corpora quadrigemina are seen on the dorsal surface of
the mid-brain, after the greater portion of the cerebral hemi-
spheres and other overlying structures have been removed.
They are four rounded eminences, placed in pairs, demarcated
by a crucial depression. The cephalic pair, the superior quad-
rigeminal bodies (pregemina or superior colliculi), are the
larger, and the pineal body lies between them. They are oval,
and of a yellowish-gray color. The superior quadrigemina
bodies, pass lateroventrad to end in the prebrachium, the latter
being continuous cephaloventrad between the overhanging
pulvinar, and the internal geniculate body. The inferior corpora
quadrigeminal bodies (postgemina or inferior colliculi) are lighter
in color than the former and passes lateroventrad to end in the
postbrachium, the latter continuing upward and forward to
pass beneath the internal geniculate body.

The internal geniculate body, or postgeniculum, is a small
oval eminence of the lateral surface of the mid-brain in which
the. internal fibers of the optic tract appear to terminate.
The inferior brachium or postbrachium runs into this body.
It is supposed to be a way station for auditory impulses in
their course to the cerebrum, also being the origin and terminus
of the arched commissure of Gudden.

The aqueduct and central aqueduct gray are best seen on
a (microscopic) cross-section of the mid-brain through the
level of the superior quadrigeminal bodies. The aqueduct is a
narrow canal connecting the third with the fourth ventricle.
It demarcates the lamina quadrigemina dorsad from the
tegmental zone, and is surrounded by the central aqueduct
gray, which contains the nuclei of origin of the oculomotor,
trochlear, and the mesencephalic root of the trigeminal nerves.

SUMMARY OF THE GRAY MASSES IN THE MID-BRAIN

Central aqueduct gray: (a) Oculomotor nerve nucleus.
(b) Trochlear nerve nucleus.

Nucleus radicis descendentis nervi trigemini.

Nucleus of medial longitudinal bundle and postcommissure.

Formatio reticularis.

Substantio nigra (intercalatum).

Red nucleus (rubrum).

PARTS DERIVED FROM THE FORE-BRAIN 315

Stratum cinereum of superior corpora quadrigemina.
Nucleus of inferior corpora quadrigemina.
Interpeduncular nucleus. (Gray.)

Parts Derived from the Fore-brain (Prosencephalon)

The prosencephalon is subdivided into the diencephalon,
or thalamic portion, and the telencephalon.

The parts found under a description of the diencephalon
include the thalamus, the pineal body or epiphysis, the external
geniculate body and ganglion habenule the posterior commissure,
the pars mammillaris hypothalami, the corpora albicantia and
posterior perforated space.

The thalami (optic thalami) are two ovoid ganglionic masses;
consisting externally of white and internally of gray. They
are best seen after the removal of the overlying structures—
the corpus callosum, the fornix, and velum interpositum—
and rest upon (ventral surface) the tegmentum of the crura;
and the central gray substance of the third ventricle.

The mesial surfaces have between them the third ventricle;
the middle commissure fuses each with the other in 90 per
cent. of the cases; these surfaces are covered by ependyma.
Its dorsal limit is marked by an ependymal ridge the tenia
thalami, fortified by a subjacent narrow band of fibers called
the stria medullaris, which may be traced to the habenular
nucleus and habenular commissure (of the pineal body). Caudad
is a depression triangular area—the trigonum habenule, situated
cephalad of the superior corpora quadrigeminal body. The
dorsal surface (a portion) is in relation with the reflection
of the ependyma of the lateral ventricle before it enters into
the formation of the plexus of the lateral ventricle; the velum
interpositum is in relation with the rest of this surface not
lined by ependyma. This surface is of a faint, whitish color
due to a thin layer of white fibers, the stratum zonule. The
tenia semicircularis is seen laterally separating this surface
from the caudate nucleus. Three eminences are seen—the
tuberculum anterius, medialis, and lateralis. The anterius
is bulged and forms the boundary of the foramen of Monro,
the aperture of communication between the lateral and third
ventricles. The caudal extremity is rounded and overhangs
the brachia of the corpora quadrigemina and is called the

316 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

pulvinar. The lateral surface is in contact with the internal
capsule.

The Connections of the Thalamus.—The thalamus is a gan-
glion interposed between the sensor tracts in the tegmentum
and the cerebral cortex as well as an important link in the
optic radiation path. Also motor tracts concerned with instine-
tive movements of an emotional nature. It is a relay station
for the various tracts which convey sensations of touch, tem-
perature, and pain from the body, extremities, head and neck,
of muscle sense, and of the special senses. It transmits these
to and receives in turn impulses from the cerebral cortex. As
an “emotional” centre it is also under the inhibitory influence »
of the cerebral cortex, which, if the emotion be not too strong,
prevents its external manifestation. (Gray.)

The pineal body is small, reddish-gray in color, found
between the caudal ends of the thalami, and occupying the
depression between the two superior corpora quadrigeminal
bodies. Above is the velum interpositum, which intervenes
between it and the splenium of the corpus callosum. Its
attached base is a hollow peduncle divided into a ventral and
dorsal stalk by the intrusion of the epiphyseal recess of the
third ventricle. The dorsal stalk continues on either side and
upon both thalami as the stria medullaris; it is also reinforced
by fibers joining the habenule of the two sides; it is some-
times called the habenular commissure. The ventral stalk is
folded over the posterior commissure.

The external geniculate body, or pregeniculum, are found on
the inferior and external aspect of the thalamus and its posterior
extremity—the pulvinar. They contain fibers which are
received in front from the outer division of the optic tract,
and behind connect with the superior quadrigeminal bodies
through the prebrachium; other fibers end in the thalamus.

(NotE.—The external and internal geniculate bodies are
generally included under the head of metathalamus.)

The nidus, or ganglion habenule, is placed in the depression
(the trigonum habenulz) between the pineal body and the
caudal end of the thalamus. They are in relation with each
other through the habenular commissure, which .is connected
with the dorsal stalk of the pineal body.

The posterior commissure is a white band of fibers crossing
from side to side in the ventral stalk of the pineal body, bridg-

. 2 i

PARTS DERIVED FROM THE FORE-BRAIN 317

ing the aqueduct at its continuation into the third ventricle.
It contains decussating and connecting fibers (1) for the median
longitudinal bundle; (2) the two thalami;. (3) the habenula nidi;
and (4) the superior quadrigeminal bodies.

(Norte. —The habenule, pineal body, and posterior com-
missure are generally included under the head of epithalamus.)

The hypothalamic tegmental substance is continuous with
the mid-brain tegmentum. It is found between the ventral
face of the thalamus, the red nucleus, and a continuation of
the substantia nigra known as the corpus hypothalamicus, or
body of Luys. The fibers contained within the hypothalamic
tegmentum communicate with the medial lemniscus, of the
superior peduncle of the cerebellum, and from the red nucleus
to end in relation with the thalamic cells. The corpus hypo-
thalamicus lies frontad to the lateral part of the substantia
nigra, and, like it, is situated between pes and tegmentum.
Its fibers decussate in the floor of the third ventricle with
those of the opposite side, dorsocaudad of the corpora albi-
cantia.

The corpora albicantia are two bodies placed side by side
in the intererural space, cephalad of the posterior perforated
substance, at a point where the floor of the third ventricle
becomes decreased in thickness to form the tuber cinereum.
They are white in color, due to a superficial layer of fibers
derived from the fornix. The fibers of the fornix terminate
in the corpora albicantia.

The posterior perforated substance marks the situation of
the interpeduncular ganglion. From it arise the fiber tracts
called the tenia pontis. It occupies the interval between the
copora albicantia, the pons, and the crura cerebri.

(Nore.—The corpora albicantia and the posterior per-
forated substance are generally included under the head of
the Pars Mammillaris Hypothalami.)

The parts found under a description of the telencephalon
include the pars opticus hypothalami, consisting of the tuber
cinereum, the pituitary body, or hypophysis, the infundibulum,
the lamina terminalis, the optic chiasm, and the optic tract.

The tuber cinereum is an elevation of gray matter between
the optic tracts and the corpora albicantia, and forms part
of the floor of the third ventricle. Its apical portion is atten-
uated, and forms the stalk of the pituitary body; the latter is

318 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

called the infundibulum; it is hollow, and its funnel-shaped
diverticulum is called the infundibular recess of the third ven-
tricle. The gray lamina composing the tuber communicates
with the central ventricular gray, and, therefore, with the
lamina cinerea, or terminalis.

Fia. 51

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Posterior
“+ division
NWA OF Sylvian
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i M\__ Tem poro-
sphenoidal
lobe.

1__ Occipital
lobe.

Base of the brain. (Gray.)

The pituitary body, or hypophysis, occupies the fossa hypo-
physeos of the sphenoid. It is composed of a_prehypo-
physeal and posthypophyseal portion. The former is developed
from the buccal cavity; the latter of a neural origin, develop-

THE CEREBRUM | 319

ing as a ventral diverticulum from the primitive neural tube.
The prehypophysis is the larger.

The lamina cinerea, or terminalis, is a thin, easily torn lamina
between the optic chiasm and anterior commissure, bounded
laterally by the cerebral hemispheres.

Optic tract (see Optic Nerve).

Optic chasm (see Optic Nerve).

The Third Ventricle

The third ventricle is derived from the primitive fore-brain
vesicle, except that portion which also enters into the forma-
tion of the lateral ventricles. It is a narrow space between
the two thalami and hypothalamic gray, limited in front by
the terma, behind continuous with the aqueduct (Sylvian),
and laterally is continuous with the lateral ventricles through
the foramen of Monro. The roof is covered by an ependymal
layer, fused with the teenia thalami, and the ependymal layer
is reinforced by a vascular fold of pia mater, the two together
constituting the velum interpositum; also the fornix. . The
floor is formed by the tuber cinereum, corpora albicantia,
and posterior perforated substance, as well as the optic chiasm
and a portion of the tegmentum of the crura cerebri.

In its cavity are three commissures: the anterior, in front of
the anterior pillars of the fornix, piercing on each side the corpus
striatum; the middle, or soft, of gray matter, connecting the
thalami; and the posterior, also connecting the optic thalami
behind, and lying in front of and beneath the pineal gland.

In front are the two openings, one on each side, of the fora-
men of Monro.

The Cerebrum

The cerebrum is the largest part of the brain, and consists
of two lateral halves, or hemispheres, separated by the great
longitudinal fissure and connected to each other by a great
commissure, the corpus callosum. The latter constitutes a
great system of association fibers for the bilateral codrdination
of corresponding cortical parts. The hemispheres are sub-
divided into lobes, and the latter present over their entire
surfaces convoluted eminences, the gyres, or convolutions, sepa-
rated by depressions, the sulci or fissures.

.

NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

320

Its

s convex from before backward

i

3

side, narrower in front than behind.

The cerebrum, as a whole

and from side to

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THE CEREBRUM 321

inferior surface is flattened and overlaps the mid-brain and
cerebellum, from which it is separated by the tentorium cere-

F,= FISSURE

G.= GYRE

(Gray.)

ROSTRAL_©

Fie. 53

PARACENTRAL F.

CENTRAL F.

PRECUNEUS
Fissures and gyres of the mesal surface of the left hemicerebrum.

CUNEUS

belli. ‘The outer surface, the cortical substance, including the
gyri, is composed of gray, while the interior is of white.
21

—

322 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The lobes are the frontal, the parietal, the occipital, the temporal
and the central lobe, or island of Reil.

Fig. 54
INTERCEREBRAL F.

=
m
n
O
Bs)
es
—!
>
xe
&

F,=FISSURE
G.=GYRE

Fissures and gyres of the basal surface of the cerebrum. (Gray.)

The frontal lobe, the lateral surface, is separated behind,
from the parietal lobe, by the central fissure or the fissure
of Rolando, and below, from the temporal lobe by the Sylvian

THE CEREBRUM O20

fissure, in part, and rests on the orbital plate of the frontal
bone. The gyres are the precentral, superfrontal, medifrontal,
and subfrontal. The fissures are the precentral, superfrontal,
and subfrontal. The orbital surface of the frontal lobe is marked
by the olfactory fissure, which lodges the olfactory bulb and
tract, and separates the mesorbital gyre from the preorbital
and postorbital gyre fields. The latter are subdivided by the
transorbital fissure. Sometimes the postorbital limbus may
be seen on this surface. It consists of a curved, welt-shaped
eminence demarcated by an incisure created by the lesser
wing of the sphenoid, and due, apparently, to the intrusion
of the postorbital portion into the middle fossa of the skull.
(Gray.)

The mesal surface of the frontal lobe presents the paracentral
gyre, limited by the caudal and cephalic limbs of the paracentral
fissure; the superfrontal and callosal gyre, separated by the
supercallosal fissure and the rostral fissure is found in the
inferior region of this surface.

The parietal lobe, lateral surface, is bounded in front by the
central fissure, below by the Sylvian fissure, above by the
dorsimesal border; it is only partially separated from the occipital
lobe by the occipital fissure, merging gradually into the tem-
poral lobe. The gyres are the postcentral, the parietal, the
subparietal the marginal, the angular, the postparietal; the
paraoccipital is the gyre connecting the parietal and occipital
gyres. The marginal connects the postcentral and super-
temporal gyres; the angular connects the supertemporal and
meditemporal gyres. The fissures are the postcentral, the
subcentral, the parietal; the paraoccipital (anterior portion).
The less constant fissures are the transparietal and the inter-
mediate fissures. In the subparietal region terminate the
upturned ends of the Sylvian (2. e., episylvian ramus), and the
supertemporal and meditemporal fissures.

The mesal surface of the parietal lobe. The precuneus
gyre is found, separated in front and above from the paracentral
gyre by the paracentral fissure, below and above, from the cuneus
by the occipital fissure; while below and in front it is demar-
cated.from the callosal gyre by the precuneal fissure.

The occipital lobe, the lateral surface is bounded anteriorly
by the occipital fissure, which partially separates it from the

324 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

parietal lobe, also the paraoccipital and exoccipital fissures are
seen extending into the lobe. °

The mesal surface presents the cuneus embraced by the
occipital and calcarine fissures; a small fissure is seen near the
posterior third of this surface, and is called the cuneal.

The temporal! lobe, the lateral surface is bounded by the basi-
sylvian and Sylvian fissures and by the ventrolateral border;
posteriorly, it merges into the adjacent parietal and occipital

lobes. The gyre are the supertemporal, the meditemporal, and

subtemporal. The fissures are the supertemporal and medi-
temporal.

The tentorial or ventral surface of the temporal lobe: The
gyre are the subcalcarine, the subcollateral, and part of the
subtemporal; near the dorsimesal part of the ventral surface
is found the hippocampal, and the uncinate gyre is found
toward the temporal pole. The fissures are the subtemporal,
collateral, and the occipitocalcarine stem, the hippocampal, and
the postrhinal. ,

The dorsal or opercular surface of the temporal lobe enters into
the formation of the Sylvian cleft. The transtemporal fissures
and transtemporal gyres are found upon this surface.

The island of Reil (central lobe or insula) is seen after separating
the lips of the Sylvian cleft, and is overlapped by the opercula;
the latter removed, the island of Reil is seen as a tetrahedral-
shaped mass with its apex directed ventrocephalad. Its borders
are sharply outlined by the circuminsular fissure, except in
the depths of the basisylvian cleft, where the insular cortex
is continuous with the gray substance of the anterior per-
forated substance or lumen insule (belonging to the rhin-
encephalon). The transinsular or central fissure divides this
area into a larger preinsular and a smaller postinsular part.
The preinsular shows four to five preinsular gyres; the postinsular
presents a single long gyre (the gyrus longus insule).

The rhinencephalon, or olfactory lobe, constitutes the central
olfactory structures, as distinguished from the rest of the
fore-brain (pallium). It comprises: (1) Peripheral parts;
(2) central or cortical portions; the former is divided into
pre- and postolfactory portions.

HORIZONTAL SECTIONS OF THE BRAIN 3020

The Peripheral Part

Bulbus olfactorius.

Tractus olfactorius.

Tuberculum olfactorium and trigonum.
Area parolfactoria (Broca).

Stria (gyrus) olfactorius medialis.
Stria (gyrus) olfactorius intermedialis.
Stria (gyrus) olfactorius lateralis.

Preolfactory lobe {

ee ee

L

8. Anterior perforated substance.
Postolfactory lobe| 9. Gyrus subcallosus and Broca’s diagonal
band.

The Cortical and Central Part

- 1. The hippocampus.!
2. The uncus.
3. Gyrus dentatus.
. 4. Fasciola cinerea.
Wehbe 5. Indusium, medial and lateral longitudinal striz
upon the corpus callosum.
6. Gyri Andree Retzii.
~ 7. Gyri subcallosi.
{ §. Fornix and fimbria.
Central | 9: Corpus albicans and albicanothalmic tract.
10. Part of anterior commissure (precommissure).
| 11. Part of septum pellucidum. (Gray.)

Horizontal Sections of the Brain

Horizontal section of the hemispheres about one-half inch
above the corpus callosum brings into view the white matter
constituting the centrum ovale minus. This is dotted with
the puncta vasculosa, due to the divided bloodvessels. A
section at the level of the corpus callosum is called the centrum
ovale magus of Vieussens.

1 Not to be confounded with the hippocampal gyre of the pallium.

326 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The anterior part of the corpus callosum forms in front a
bend, the genu, and this extends back along the base of the
brain up to the lamina cinerea as the rostrum. Here it sends
off the peduncles of the corpus callosum. Behind it forms a
thick border, the splenvwm, or pad. The under surface of the
corpus callosum is connected behind with the fornix and for
the rest of its extent with the septum lucidum. It forms the
roof of the lateral ventricles.

The corpus callosum is a mass of transverse fibers seen on
separating the hemispheres of the cerebrum. It is best studied
from a view of a mesial section. The mass of radiating fibers
pass transversely, connecting almost every part of one cere-
bral hemisphere with the corresponding part of the other.
They radiate in various directions within the hemispheres,
and are divided into a pars frontalis, a pars parietalis, and a
pars occipitalis.

A portion of the dorsal surface is free for a width of about
1 cm. on either side of the mesial plane, partly covered by the
indusium, and overlapped by the callosal gyres, a fold of pia
intervening.

It is a long, thick, somewhat flattened arch of white, bend-

ing upon itself anteriorly to form the genu, while its posterior
extremity is rounded and somewhat folded to form the splenium.
The genu becomes reflected to form the rostrum, which ends
in a flattened portion called the cupola, which in turn joins
the lamina terminalis in front of the anterior commissure.

The Lateral Ventricles

The lateral ventricles are serous cavities, have a thin lining
membrane, covered by a layer of epithelium cells (ependyma),
which secrete a serous fluid. They are contained one in each
hemisphere, separated by the septum lucidum, and each is
divided into a body and three cornua, an anterior, posterior,
and middle. The foramen of Monro connects them with the
third ventricle.

The central cavity, or body, is roofed by the corpus callosum,
and in the floor, from without inward, are found the caudate
nucleus of the corpus striatum, tenia semicircularis, part of
the optic thalamus, choroid plexus, and part of the fornix.

THE LATERAL VENTRICLES 327

The anterior cornu projects into the anterior lobe and runs
outward around the nucleus caudatus. Above and in front of
it is the corpus callosum.

The posterior cornu, or digital cavity, runs back into the
posterior lobe, its direction being backward, outward, and
lastly inward. Its floor presents the eminence of the hippo-
campus minor, or calear avis. At the junction of the posterior
and middle cornua is the eminentia collateralis, or pes accessorius.

The middle or descending cornua curves around the back of
the optic thalamus, descending at first backward and out-
ward. It then runs downward, forward, and lastly inward.
In its floor are the hippocampus major and pes hippocampi,
corpus fimbriatum, and choroid plexus; the fascia dentata
lies within the hippocampal or dentate fissure, and the trans-
verse fissure runs along the inner side of the cornu.

The fornix is an arched longitudinal commissure of white
matter below the corpus callosum, its lateral margins forming
part of the floor of the body of the lateral ventricles. In front
its two lateral halves are divergent, and form the anterzor
pulars; behind they diverge into the two posterior pillars;
the central part is the body. The body is triangular, attached
above to the corpus callosum and septum lucidum; below
the velum interpositum separates it from the third ventricle
and optic thalami. From under each side project the choroid
plexuses.

The anterior pillars descend through the gray matter on the
sides of the third ventricle and form the anterior boundaries
of the foramen of Monro. Then they emerge at the base of
the brain to form the corpora albicantia, from which each
pillar turns upward and ends in the corresponding optic thala-
mus. In their course each communicates with the peduncle
of the pineal gland and the teenia semicircularis.

The posterior pillars are connected with the corpus callosum,
then enter the dscending cornua, and are partly prolonged
into the upper surface of the hippocampus major and partly
into the corpus fimbriatum.

The foramen of Monro is a foramen connecting each lateral
ventricle with the anterior part of the third. In front it is
bounded by the anterior pillar of the fornix; behind, by the
anterior part of the optic thalamus; above, by the anterior
_ extremity of the body of the fornix.

328 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The velum interpositum is a process of the pia mater which
occupies the great transverse fissure, and hence separates
the fornix from the third ventricle. In front it sends a process
through the foramen of Monro to each lateral ventricle. From
its under surface it supplies the two vascular processes which
form the choroid plexuses of the third ventricle, and on each
side the choroid plexuses of the lateral ventricles are found.

The Third Ventricle

This is the expanded interval into which the Sylvian aqueduct
opens, and which lies between the optic thalami. The velwm
interposittum, with the choroid plexuses, connected on each
side with the peduncles of the pineal gland, forms its roof to-
gether with the posterior commissure. Its floor presents the
lamina cinerea, tuber cinereum, infundibulum, corpora albi-
cantia, posterior perforated space, and tegmentum of crura.
In front it is bounded by the anterior commissure and the
lamina cinerea. Behind is the opening of the aqueduct of
Sylvius.

The corpus striatum is a mass of gray matter, and consists
of an extraventricular portion embedded in the hemisphere,
and called the lenticular nucleus, and an intraventricular
part in the body and anterior cornu, the nucleus caudatus.

The caudate nucleus is pyriform, projecting into the body
and anterior cornu by its broad end, and by its smaller end
into the roof of the middle cornu nearly to its tip.

The lenticular nucleus is divided into three zones, visible
on transverse vertical section. It is separated from the caudate
nucleus by the internal capsule, and the eaternal capsule separates
it from the claustrum. This nucleus and the caudate are joined
together .in front, being continuous with the gray matter of
the anterior perforated space.

The claustrum is a gray lamina marked externally by ridges
and furrows corresponding to the gyres and sulci of the island
of Reil.

The nucleus amygdale is a small gray mass projecting into
the apex of the middle cornu, and continuous with the cortical
part of the apex of the temporal lobe.

~ » sda

THE BASE OF THE BRAIN 329

The teenia semicircularis lies in a groove between the caudate
nucleus and the optic thalamus. In front it joins the anterior
pillar of the fornix; behind it enters the nucleus amygdale.
Beneath it is the vena corporis striati.

The choroid plexus is a very vascular fringe covered with
epithelium continuous with that of the ependyma, and forms
the border of the velum interpositum. It extends from the
foramen of Monro, where it is continuous with the other,
across the floor of the body of the ventricle and into the middle
cornu.

The corpus fimbriatum is the narrow band of white matter
on the hippocampus major into which is prolonged the posterior
pillar of the fornix.

The hippocampus major is a curved white prominence in
the floor of the middle horn. Its lower part presents the appear-
ance of a paw from its grooves and eminences, hence called
the pes hippocampi. The hippocampus major is caused by
the dentate fissure, and the gray matter contained in this
fissure (dentate convolution) projects as a free margin—the
fascia dentata.

The eminentia collateralis (pes accessorius) is formed by the
collateral fissure.

The great transverse fissure of Bichat, separating the cere-
brum and cerebellum, lies between the fornix and the splenium
of the corpus callosum above and the corpora quadrigemina
below; laterally, it lies between the back part of the optic
thalamus below and the corpus fimbriatum and fascia dentata
above: It is really a cleft into the ventricle, produced by
pulling out the pia forming the velum interpositum.

The septum lucidum separates the lateral ventricles. It
is composed of two layers, a small space containing fluid being
left between them called the fifth ventricle. It is attached
above to the corpus callosum, below to the anterior pillars
of the fornix and the reflected portion of the corpus callosum.

The Base of the Brain

On the under surface of the encephalon are found the base
of the frontal, resting on the orbital plate of the frontal bone
and the temporal lobe, of which there are a middle and a pos-

330 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

terior portion; the former lying in the middle fossa of the
skull and the posterior lying on the upper surface of the ten-
torium cerebelli.

From before backward the following parts come into view:
Longitudinal fissure, corpus callosum, lamina cinerea, olfactory
bulb and tract, fissure of Sylvius, anterior perforated space,
optic commissure, tuber cinereum, infundibulum, pituitary body,
corpora albicantia, posterior perforated space, crura cerebri, pons,
medulla, and cerebellum.

The great longitudinal fissure completely separates the right
and left hemispheres, and at the bottom of it is the corpu
callosum. .

The corpus callosum is placed nearer the front than the
back of the hemispheres, being convex from before backward
above, concave below; the fibers run transversely, but along
the middle line is a longitudinal raphé with a white band on
each side, the mesial longitudinal striez, and near the margin
some lateral longitudinal strie.

The lamina cinerea is a thin layer of gray matter lying be-
tween the chiasma and the corpus callosum, and continuous
with the gray matter of the anterior perforated space on each
side. It forms part of the floor and anterior boundary of the
third ventricle.

The olfactory tract runs in a groove close to the great longi-
tudinal fissure on the under surface of the frontal, and ends
in an enlargement, the bulb, from which the olfactory nerve
descends through the cribriform plate. Behind, the tract
divides into two roots. The outer runs back along the margin
of the anterior perforated space to the Sylvian fissure; the
inner to the longitudinal fissure. The triangular space between
the two roots is occupied by gray matter forming part of the
tuber olfactorium, which lies in a depression on the frontal lobe,
and is composed internally of white matter.

The fissure of Sylvius lodges the middle cerebral artery.
At its inner part is the fasciculus unciformis, connecting the
frontal and temporal lobes.

The anterior perforated space is a triangular depression at
the inner side of the Sylvian fissure, of a grayish color, and is
pierced by many small vessels passing to the corpus striatum,
under which it lies.

The optic commissure, or chiasma (see Optic Nerve), is formed

2" o) eee ees

THE BASE OF THE BRAIN dol

by. the union of the two optic tracts. It lies below the lamina
cinerea and in front of the tuber cinereum.

Between the optic tracts and the crura cerebri is a diamond-
shaped area, the interpeduncular space. ‘This space includes
the tuber cinereum, infundibulum, pituitary body, corpora
albicantia, and the posterior perforated space.

The tuber cinereum is an elevation of gray matter between
the optic tracts and corpora albicantia, and forms part of the
floor of the third ventricle. From its under surface the infundib-
ulum runs down to the pituitary body. The former is hollow
and of a conical form, its cavity communicating with the
third ventricle.

The pituitary body, or hypophysis cerebri, is a reddish-gray
mass occupying the sella turcica. Its weight is from 4 to 10
grains. It consists of two lobes, the anterior and larger of
which encloses the posterior. The former is of a yellowish-
gray color; the latter in fetal life contains an aperture which
communicates with the infundibulum.

The corpora albicantia are two bodies placed behind the
tuber cinereum. They are composed of white matter, are
about the size of a pea, and contain each a gray nucleus which
is connected with its fellow across the median line. Each
is formed by the corresponding anterior pillar of the fornix.

The posterior perforated space forms part of the posterior
portion of the floor of the third ventricle, and is pierced by
small vessels for the optic thalami. It occupies the interval
between the corpora albicantia, the pons, and the crura
cerebri.

The crura cerebri are broader in front than behind and less
than one inch in length. They run from the upper border of
the pons to the hemispheres of the cerebrum, under the optic
tracts, which cross: them. The fourth nerve crosses the outer
side, and the third issues from the inner side of each.

Each crus is composed of two parts separated by gray matter,
the locus niger. The ventral part, or crusta, is a continuation
of the pyramidal fibers from the medulla and pons, while the
dorsal part, or tegmentum, is the continuation of the deep
longitudinal fibers of the pons. The crustz of the two sides
are entirely separate, but the tegmenta are connected at the
median line.

3382 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

Cortical Localization of Function

Motor Area.—Comprises the precentral gyre and parts of
the frontal gyres adjacent thereto, together with the para-
central, and the adjacent portion of the superfrontal gyre on
its mesal aspect. This area comprises the centres for the
muscle control of the following parts of the body located as
follows:

le. eee

Mesal view of left cerebral hemisphere, showing localization of functions.

Lower limbs.—Dorsal part of precentral and paracentral
gyres.

Trunk.—Frontad both on the mesal aspect and in the dorsal
superfrontal gyre.

Upper Limb.—Midportion of precentral gyre.

Facial.—Ventral part of precentral gyre.

Tongue, Larynx, Muscles of Mastication, Pharynx.—Frontal
opercular part. ;

Movements of Head and Eye.—Medifrontal gyre, adjacent
to precentral gyre.

Owing to a decussation of the pyramidal (motor) tracts
in their course to the primary motor centres, the motor centres

CORTICAL LOCALIZATION OF FUNCTION 3090

in one cerebral hemisphere control the movements of the
opposite side of the body.

Sensor Areas.—Tactile and temperature impressions. Post-
central gyre, in corresponding order with the neighboring pre-
central motor area; the postcentral (sensor) and precentral
(motor) gyres are so closely associated in the highest category of
the reflex are system represented in the cerebral cortex that
they are included under the term of sernesthetic or sensomotor
area, devoted to the registration of cutaneous impressions,
impressions from the muscles, tendons, and joints; in short, the
sense of movement.

Lateral view of left cerebral hemisphere, showing localization of functions. (Gray.)

Stereognostic Sense Area (concrete perception of the form
and solidity of objects).—Parietal gyre, and its extension in
the precuneus on the mesial aspect.

Auditory Area.—Middle third of supertemporal and adjacent
transtemporal gyres in the Sylvian cleft.

Visual Area.—Calcarine fissure, and cuneus as a whole.

Olfactory Area.—Uncus, frontal part of hippocampus, indu-
sium, subcallosal gyre, parolfactory area, and anterior perforated
substance. ;

334 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

Gustatory Area.—Probably in region of the olfactory area
in the temporal lobe (uncinate and hippocampal gyre?) (not
definitely settled).

Language Areas.—Emissive (articular) centre for speech (con-
trol of muscles used in speech; larynx, tongue, jaw muscles).
Junction of subfrontal gyre with the precentral gyre.

Auditory perceptive centre (word deafness) also the lalognostic
(word understanding) centre.—Marginal gyre and adjacent parts
of super- and meditemporal gyre.

Visual receptive centre (word blindness).—Angular gyre.

Emissive “Writing”? Centre-—Medifrontal gyre, in front of
motor area for the upper limb (this has not been definitely
proved or accepted).

Language Arrangement Centre.—Island of Reil or insular
association area serving to connect the various receptive sense
areas relating to the understanding of the written and spoken
word with the somesthetic emissary centre related to articulate
speech and writing.

Association Areas.—Under this heading are included the
frontal association area concerned, as far as is known, with
the powers of thought in the abstract, creative, constructive,
philosophic. The parieto-occipito-temporal area were concerned
with the powers of conception of the concrete, for the com-
prehension of analogies, comparing, generalizing, and system-
atizing things heard, observed, and felt. (Gray.)

THE PERIPHERAL NERVOUS SYSTEM
THE CRANIAL NERVES

The cranial nerves consist of twelve pairs, as follows:

I. Olfactory (fila). VIII. Acoustic,
II. Optie. 1. Cochlearis.
III. Oculomotor. 2. Vestibularis.
IV. Trochlear. IX. Glossopharyngeal.
V. Trigeminal. X. Vagus.
VI. Abducent. XI. Spinal accessory,
VII. Facial, 1. Accessory to vagus.
Nervus intermedius. 2. Spinal part.

XII. Hypoglossal.

THE OPTIC NERVES O00

These nerves have each a superficial and a deep origin.
The former corresponds to its point of attachment at the
surface of the brain; the latter to certain nuclei or collections
of nerve cells in the structure of the brain.

; The Olfactory Nerves

The olfactory nerves, or fila, are the special nerves of the
sense of smell. Twenty in number on each side. They are
distributed to the olfactory region in the upper part of the
superior turbinated process of the ethmoid and corresponding
portion of the nasal septum. ‘These filaments represent the
axones of the olfactory cells and pass through the cribriform
plate of the ethmoid to join the under surface of the olfactory
bulb, which rests on the cribriform plate, and is the oval
mass of a grayish color that forms the anterior extremity of
a slender process of brain substance called the olfactory tract.
The olfactory nerves differ in structure from the other nerves,
containing only amyelinic fibers.

The Optic Nerves

The fibers of the optic nerves, the special nerves of the sense
of sight, are situated in the retina; they start as the central
processes of the ganglion cells, which converge and pierce the
choroid and sclera as a cylindric cord. The point of emergence
is situated a little internal to the posterior pole of the globe.
Passing through the orbital fat, in an inward and backward
direction, it passes through the optic foramen to end in the
optic chiasm. The optic chiasm is somewhat quadrilateral
in shape, rests on the olivary eminence and the diaphragma
sella, being bounded above by the lamina terminalis; behind,
by the tuber cinereum; on either side by the anterior perforated
substance. Within the chiasm the fibers decussate as follows:
Those from the nasal side of the left and right halves of the
retina cross in the centre, to the opposite optic tract; those
from the temporal side of the right and left eyes pass back-
ward without decussating, to end in the optic tract. In the
posterior portion of the chiasm is Gudden’s commissure, which
contains fibers, completing an are with the medial geniculate
bodies on either side. The fibers from the temporal sides of

336 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

both eyes after leaving the chiasm send fibers to the pulvinar,
the lateral geniculate bodies, and an inner set which pass to
the superior quadrigeminal bodies. The fibers from the nasal

Fic. 57

\|
Infratrochlear §
nerve.

OQ 1d UWLOLT GIG

prowyas fo

» z \ ? %
x
jj \

AEN. (l
\ Recurrent filament’
to dura mater.

Motor root.
Sensory root.

Nerves of the orbit. Seen from above. (Gray.)

side of both retina, after decussating in the chiasm, pass to
the pulvinar and lateral geniculate bodies, through an outer
set of fibers, and communicate also with the superior quad-

THE TROCHLEAR 337

rigemina bodies, by means of an inner set of fibers. The bond
of union between the cuneus and the pulvinar and lateral
geniculate bodies is by means of fibers, called the optic radiation.
The latter transmit visual impulses to the cortex. The inner
set of fibers in the optic tract pass to the superior quad-
rigeminal bodies, then-to the nuclei of the third, fourth, and
sixth nerves, at the same time receiving fibers from the cortical
centre (corticifugal tract) contained within the optic radiation.
Thus through the superior quadrigeminal bodies reflex paths
pass to the eye-muscle centres and in their turn are influenced
by the cortical centres through the corticifugal tract.

The Oculomotor

The oculomotor arises superficially from the crus anterior
to the pons, its deep origin being a gray nucleus in the floor
of the aqueduct of Sylvius. It runs to the outer side of the
posterior clinoid process, enters the cavernous sinus, runs
above the other nerves in its outer wall, and divides into two
branches, which enter the orbit between the two heads of the
external rectus. It is joined in the sinus by sympathetic fila-
ments. The superior branch crosses the optic nerve to supply
the superior rectus and levator palpebre. The inferior divides
into three parts—one for the inferior oblique, one to the inner,
and one to the lower rectus. The first supplies the motor root
of the lenticular ganglion.

The Trochlear

The trochlear nerve has an apparent origin laterad of the
frenulum veli, immediately behind the posterior quadrigeminal
body, and a deep from the floor of the aqueduct of Sylvius.
The two nerves communicate by a transverse band on the
valve of Vieussens. The nerve pierces the dura after crossing
over the crus, enters the cavernous sinus, in whose outer
wall it lies between the ophthalmic and third nerves, then
crosses the latter to enter the orbit through the sphenoidal
fissure above the external rectus, and enters the superior
oblique after crossing over the levator palpebree. It receives
sympathetic filaments in the sinus, and sends a recurrent
branch into the tentorium.

22

308 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The Fifth Nerve °

The fifth or trifacial is the largest of all the cranial nerves, 7
and arises by two roots, a motor and a sensor. ‘The former .
: q

Fie. 58 }

Sensory root.
Motor_root.
eS

) f

a ,
FANSSHINS g@
Sain a Inf ez
\

U

Distribution of the second and third divisions of the fifth nerve and submaxillary
ganglion. (Gray.) ;

is small, and the latter has the Gasserian ganglion upon it.
Both arise from the side of the pons superficially, the smaller

:
4
j

Internal carotid artery
and carotid plexus.

‘2004 LOsuay

"7004 LOOT,

.
THE FIFTH NERVE | 339

root above the larger, some transverse fibers of the pons separat-
ing the two. This nerve confers both motion and sensation.
At the apex of the petrous portion of the temporal the large
root forms the Gasserian ganglion; the smaller does not join in
the ganglion, but runs below it to join, just below the foramen
ovale, the lowest trunk proceeding from the ganglion.

Fia. 59

Upper division
of third nerve.

Orbital
nerve.

uowrmrp LanoT

Nerves of the orbit and ophthalmic ganglion. Side view. (Gray.)

The Gasserian ganglion lies in a hollow near the apex of the
petrous portion of the temporal, the large superficial petrosal
nerve, and the motor root lying below it. It receives branches
from the carotid plexus. Small twigs pass to the dura mater.
This ganglion sends off three large branches, viz., the ophthal-
mic, superior maxillary, and inferior maxillary.

The first two confer sensation, the third, motion and sensa-
tion.

The ophthalmic nerve, or first division of the fifth nerve,
is sensor, and the smallest branch of the ganglion. It is
flattened, about one inch long, and runs in the outer wall of the

340 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

cavernous sinus, being the lowest of the nerves. It receives
filaments from the cavernous plexus, and gives off filaments
to the third and sixth, and sometimes to the fourth nerve,
and a recurrent branch running in the tentorium with the
_ fourth. Finally, it divides into the frontal, lacrymal, and
nasal nerves, which pass through the sphenoidal fissure into
the orbit.

The lacrymal, the smallest, runs with the lacrymal artery
above the external rectus muscle to the gland, which it supplies,
as well as the conjunctiva, communicating with the superior
maxillary nerve. It then pierces the palpebral ligament to
end in the upper lid, joining branches of the facial.

The frontal, the largest branch, enters the orbit through
the widest part of the sphenoidal fissure, just below the peri-
osteum, and divides about the middle of the orbit into the
supratrochlear and supraorbital nerves. The former runs in
over the pulley of the superior oblique, and leaves the orbit
between it and the supraorbital foramen. It then ascends
beneath the muscles and ends in the skin of the forehead. It
communicates in the orbit with the infratrochlear nerve.
The frontal nerve continues as the supraorbital, which passes
through the supraorbital foramen, supplies the upper lid, and
divides into an inner and an outer branch. These ascend on
the forehead and supply the pericranium and skin, the outer
reaching nearly to the lambdoid suture.

The nasal enters the orbit between the two divisions of the
third nerve, and between the heads of the external rectus,
and then crosses over the optic nerve and runs to the anterior
ethmoidal foramen. In the orbit it gives off a branch to the
ophthalmic ganglion, one long ciliary to the eyeball, and an
infratrochlear branch. It then reénters the cranial cavity
through the anterior ethmoidal canal. In the cranium it
runs in a groove on the cribriform plate, and through a slit
on the side of the crista galli into the nose, where it gives
off an external and an internal branch. The latter supplies
the mucous membrane of the septum, and the external the
outer wall of the nasal fossa. The nerve then runs in the
groove on the nasal bone to end as the anterior branch in the
integument of the tip of the nose, joining facial branches.

The ophthalmic ganglion is found at the back of the orbit,
between the optic nerve and the external rectus. It has three

Se a!

THE FIFTH NERVE 341

roots, viz., the long or sensor, from the nasal branch of the
ophthalmic; a short or motor, from the branch of the third
to the inferior oblique; and the sympathetic root, from the
cavernous plexus.

Branches.—Six or eight short ciliary, which run with the
ciliary arteries above and below the optic nerve, and are joined
by a branch from the long ciliary of the nasal. They pierce
the sclerotic to supply the ciliary muscle and iris.

The second division of the fifth nerve (superior maxillary) is
sensor and enters the foramen rotundum, crosses the spheno-
maxillary fossa, and, as the infraorbital, traverses the canal,
emerges from the foramen to end on the face in palpebral,
nasal, and labial branches—the first set, to lower lid; the second,
to side of nose; and the third, to upper lip. These branches
join with the facial to form the infraorbital plexus. The superior
maxillary nerve also gives off two branches to Meckel’s ganglion,
an orbital and alveolar branch, and a recurrent branch to the
dura mater.

The orbital or temporomalar branch enters the orbit by the
sphenomaxillary fissure, and divides into two branches, which
pierce the malar bone. The malar branch supplies the skin
of the cheek, and joins the facial. The temporal branch, after
piercing the malar bone, enters the temporal fossa, and ends
in the skin over the forepart of the temporal region, joining
the facial and auriculotemporal nerves.

The alveolar or superior dental nerves are three: The pos-
terior divides into two, which run on the zygomatic surface
of the superior maxilla, supplying the gum and the mucous
membrane of the cheek, and enter the posterior dental canals
to the molar teeth. The middle runs to the bicuspids along
a canal in the antrum. The anterior descends in its canal,
and gives a nasal branch to the pituitary membrane, and
dental branches to the canine and incisor teeth.

Meckel’s ganglion is also called the sphenopalatine, and
lies in the sphenomaxillary fossa, close to the sphenopalatine
foramen and below the superior maxillary nerve. Its motor
root comes from the facial through the large superficial petrosal
from the geniculate ganglion (see Vidian Nerve), its sensor root
from the two ganglionic branches of the superior maxillary
nerve, and the sympathetic root from the carotid plexus through
the large deep petrosal. Its branches are as follows:

342 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM
7

Ascending.—Several through the sphenomaxillary fissure to
the orbit. They may supply the periosteum.

Descending.—The small or posterior runs with a small artery
in the lesser palatine canal. It supplies the levator palati
and azygos uvule.

The large or anterior runs in the posterior palatine canal,
thence in branches to the incisor teeth along grooves in the
hard palate, and one joins the nasopalatine nerve. It gives
off inferior nasal branches, through canals in the palate bone,
to supply the spongy bones.

The external to the outer part of the soft palate, through
the external palatine canal.

The internal branches include the nasopalatine and the
upper nasal nerves. The latter run through the sphenopalatine
foramen to the spongy bones and septum. The nasopalatine
nerve proceeds with the above, and then descends on the
septum nasi, beneath the pituitary membrane, and through
the mesial divisions of the anterior palatine canal, called the
foramina of Scarpa, the left anterior to the right. They supply
the mucous membrane behind the incisor teeth.

The Vidian is formed by the large superficial petrosal and the
large deep petrosal nerves. The former is a motor branch from
the geniculate ganglion of the facial in the aqueductus Fallopii;
it passes through the hiatus canalis facialis, enters the cranial
cavity, runs in a groove on the anterior surface of the petrous
portion of the temporal bone, beneath the dura. It then
pierces the cartilaginous substance enclosing the foramen lacerum
medium, and joins the large deep petrosal. The large deep
petrosal is given off from the carotid plexus, passing external
to the internal carotid artery. It pierces the cartilaginous sub-
stance of the foramen lacerum medium, and joins the large
superficial petrosal. The Vidian begins from the cartilaginous
substance of the foramen lacerum medium, then passes through
the Vidian Canal, with the artery of the same name, and is
joined by a branch from the otic ganglion. It ends in Meckel’s
ganglion.

Posterior Branches.—The pharyngeal nerve passes through
the pterygopalatine canal to the mucous membrane of the
pharynx. |

The inferior maxillary nerve (third division of the fifth) is
the largest branch, and arises by two roots—a large sensor

:
|

eo ee

mie @

THE FIFTH NERVE 343

root from the Gasserian ganglion and the motor root of the
fifth. This nerve divides into two trunks, anterior and posterior.
The anterior gives off the masseteric, the buccal, the deep
temporal, and the two pterygoid nerves.

The masseteric runs above the external pterygoid, crosses
the sigmoid notch to the masseter, supplying also filaments to
the jaw.

The deep temporal are thscs. the posterior, middle, and

anterior.
_ The buccal is a sensory nerve, and runs along the inner sur-
face of the coronoid process to divide, on the buccinator, into
branches to the muscles and skin joining the facial, and extend-
ing as far as the angle of the mouth.

The pterygoid, internal and external, supply thine muscles
respectively.

The posterior trunk of the inferior maxillary is mostly sensory.
It divides into the auriculotemporal, gustatory, and inferior
dental.

The auriculotemporal runs beneath the external pterygoid,
the middle meningeal artery passing up between its two roots
of origin to the inner side of the neck on the lower jaw. It
then passes up under the parotid gland, and along with the
temporal artery over the zygoma, and divides into temporal
branches to the skin of the temporal region, joining the facial.
This nerve communicates at its origin with the otic ganglion,
and gives off the following branches:

Auricular, the inferior to the external meatus, the superior
to the tragus and pinna.

Articular, one or two to the articulation of the jaw; several
to the parotid, and the branches to the external auditory meatus
send a filament to the membrana tympani.

The inferior dental nerve runs along with the artery, enters
that canal, supplies the teeth, and at the mental foramen
divides into an incisor and'a mental branch. The former supplies
the canines and incisors, the latter the skin of the chin and
lower lip. The nerve is at first under the external pterygoid;
later, between the ramus of the jaw and the internal lateral
ligament. Its branches are the mylohyoid and dentals. The
mylohyoid runs in the groove to supply the mylohyoid and
anterior belly of the digastric muscles. The dentals supply
the molars and bicuspids, interlacing to form a fine plexus,
the inferior dental.

344 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The gustatory or lingual nerve lies at first beneath the
external pterygoid, internal to the dental nerve. Here a branch
from the dental may cross the internal maxillary to join it.
The chorda tympani also joins it. The nerve now runs along
the inner side of the ramus of the jaw, and crosses the upper
constrictor to the side of the tongue above the deep part of
the submaxillary gland; lastly, it runs below Wharton’s duct,
and superficially along the side of the tongue to its apex. It
communicates with the facial through the chorda tympani,
the submaxillary ganglion, inferior dental, and hypoglossal.
It supplies the mucous membrane of the mouth and tongue
(anterior two-thirds), the gums, sublingual gland, and the
filiform and fungiform papillee.

The submaxillary ganglion is placed above the deep part of
the gland, and receives filaments from the gustatory and: from
the inferior maxillary nerve through the chorda tympani; also
filaments from the sympathetic plexus around the facial artery.

Branches.—Five or six to gland, Wharton’s duct, and the
mucous membrane of the mouth.

The otic ganglion is of a reddish color, oval and flattened
in form, and ¢ inch in diameter. It lies on the inferior maxillary
nerve (deep surface) below the foramen ovale, and behind it
is the middle meningeal artery. It communicates with the
inferior maxillary through its internal pterygoid branch, with
the glossopharyngeal (possibly sensor) and facial (possibly
motor) through the small superficial petrosal nerve, continud
from the tympanic plexus, and with the plexus on the middle
meningeal artery.

Branches.—One to the tensor tympani, to tensor palati,
to chorda tympani; and to the auriculotemporal nerve two,
and sphenoidal branch to the sphenopalatine ganglion.

The Sixth Nerve

The sixth or abducens has an apparent origin in the groove
between the pons and medulla, and a deep origin from the
fasciculus teres. It runs to the lower and outer part of the
dorsum sellz, and traverses the floor of the cavernous sinus
external to the carotid artery, and, receiving branches from
the cavernous and carotid plexuses, enters the orbit by the

eee ee er eg Oe ere

ee

THE SEVENTH NERVE 345

sphenoidal fissure between the two heads of the external rectus;
it receives a branch from the ophthalmic nerve, and supplies
the above-named muscles.

Fie. 60

Lacrimal
Frontal. Ase dala

Trochlear.

Inferior division of oculo-motor.
Abducent.

Relations of structures passing through the sphenoidal fissure. (Gray.)

The Seventh Nerve

The seventh or facial has a superficial origin from the depres-
sion between the olivary and restiform bodies, and a deep
from the fasciculus teres. Between it and the eighth is the pars
intermedia, which joins the facial in the auditory canal. The
nerve runs outward to the internal meatus, where it runs in a
groove on the auditory nerve, enters the aqueductus Fallopii,
and emerges at the stylomastoid foramen. It presents within
the aqueduct, near the hiatus Fallopii, a reddish enlargement,
the genttulate ganglion. Outside the cranium it runs forward
in the parotid gland, and divides behind the ramus into the
cervicofacial and temporofacial divisions. In the parotid and
vicinity the radiating branches form the pes anserinus.

Communicating Branches.—In the internal auditory meatus,
one or two, communicating with auditory nerve.

In the aqueduct it communicates with Meckel’s ganglion by
means of the large superficial petrosal; with the otic ganglion by
a small branch to the small superficial petrosal; with the sym-
pathetic, on the middle meningeal, by the external petrosal; and
with the pneumogastric (auricular branch).

346 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

Outside the cranium: it sends branches to the glossopharyn-
geal, carotid plexus, auricularis magnus, auriculotemporal], and
facial nerves.

Branches of Distribution.—In the aqueduct: a tympanic branch
to the stapedius, and the chorda tympani. The latter arises close
to the stylomastoid foramen, ascends in a small canal to the
posterior wall of the tympanum, and then passes over the upper
part of the membrane between the handle of the malleus and
the incus, finally emerging through the canal of Huguier; it
then descends on the inner side of the internal lateral ligament
of the jaw, and joins the gustatory nerve, through which its
fibers reach the submaxillary ganglion and lingualis muscle. It
receives a branch from the otic ganglion before joining the
lingual.

Outside the Cranium.—The posterior auricular ascends between
the ear and the mastoid, receives a branch from the vagus, one
from the auricularis magnus, and one from the occipitalis minor,
and divides into an auricular branch to the back of the auricle
and retrahens, and an occipital branch to the occipitofrontalis.

The digastric branches, to the posterior belly of the digastric,
one joining the glossopharyngeal nerve; and a stylohyoid branch
to the muscle, joining the carotid plexus.

The temporofacial division crosses the external carotid artery
and the temporomaxillary vein in the upper part of the parotid,
receives filaments from the auriculotemporal nerve, and divides
into three sets of branches, viz., temporal, malar, and infra-
orbital.

The temporal branches supply the attolens and attrahens,
occipitofrontalis, orbicularis, and corrugator supercilii. They
communicate with the auriculotemporal, temporal branch of
the superior maxilla, and supraorbital nerves. ’

The malar branches run to the outer angle of the orbit, supply
the orbicularis and:corrugator, joining the lacrymal and supra-
orbital, and some, to lower lid, join with the superior maxillary
nerve (palpebral branches).

The infraorbital group, to the space between the orbit and
mouth. They supply the buccinator, orbicularis oris, the
levator labii superioris, the levator anguli oris, and nasal
muscles. They unite with the cervicofacial branches, the nasal,
infratrochlear, and with the superior maxillary nerve. The
latter forms the infraorbital plexus.

=~

THE SEVENTH NERVE 347

Terminations
of supratrochlear.

' of infratrochlear
of nasal.

nV} | Here A TINS
ee \ /\ oWs2 Hi): Hh
\

| Now

The nerves of the scalp, face, and side of the neck. (Gray.)

348 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The cervicofacial division descends through the parotid,
joining branches of the great auricular, and divides, near the
angle of the jaw, into buccal, supramaxillary, and inframaxillary
branches. ;

The buccal cross the masseter, supply the’ buccinator and
orbicularis oris, and join the infraorbital nerves and the buccal
nerve from the inferior maxillary.

The supramaailary, beneath the depressor anguli oris,
supplies the inferior labial muscles, and joins branches of the
inferior dental.

The inframazillary pierces the deep cervical fascia, supplies
the platysma, and forms arches in the suprahyoid region,
joining the superficial cervical nerve.

The Auditory Nerve

The eighth or auditory is the special nerve of the sense of
hearing. Superficially it appears at the lower border of the
pons, external to the facial. It has two roots—one from the
inner side of, and one from the front of, the restiform body.
It runs to the internal auditory meatus with the facial nerve,
the two being separated by the pars intermedia and the audi-
tory artery. The nerve in the meatus divides into a cochlear
and a vestibular branch, whose distributions within the ear
are described under the special sense of hearing.

The Ninth Nerve

The ninth or glossopharyngeal arises superficially by several
filaments from the dorsolateral groove at the upper part of the
medulla; deeply through the lateral tract to a gray nucleus in
the floor of the fourth ventricle.

The nerve runs in front of the flocculus to pass through the
middle part of the jugular foramen with the vagus and spinal
accessory, in a separate sheath, and here presents two succes-
sive ganglionic enlargements, the jugular and the petrous
ganglia. Outside the cranium it passes between, the jugular
vein and the internal carotid artery, descending in front of
the latter, and beneath the styloid process and its muscles,
to the lower border of the stylopharyngeus. It then crosses

THE NINTH NERVE 349

this muscle and divides into branches beneath the hyoglossus.
In the jugular foramen it grooves the lower border of the
petrous portion of the temporal.

The upper or jugular ganglion is of small size, and is formed
in the outer part of the nerve, some fibers passing over but
not joining it.

The petrous ganglion is larger, and lies in a groove in the
petrous bone, involving the entire trunk of the nerve. From
it pass the tympanic nerve and branches of communication
to the vagus and sympathetic. That to the sympathetic
joins the upper cervical ganglion. To the vagus, one joins
its auricular branch and one its upper ganglion. Another
branch perforates the posterior belly of the digastric, from a
point just below the petrous ganglion, to join the facial close
to the stylomastoid foramen.

The tympanic (Jacobson’s nerve) runs in a canal in the
petrous portion to enter the tympanum through an aperture
in its floor close to the inner wall, and divides into branches
which groove the promontory and form the tympanic plexus.
It gives a branch to the fenestra rotunda, fenestra ovalis, and
to the Eustachian tube. The nerve finally emerges from the
tympanum by a cana! at its upper and back part, as the small
superficial petrosal nerve. This latter enters the cavity of the
skull by a small foramen on the anterior surface of the petrous
portion external to the hiatus Fallopii, and escapes by a small
foramen in the great wing of the sphenoid, sometimes the
foramen ovale, to join the otic ganglion.

The tympanic nerve sends a communicating branch to the
carotid plexus, the small deep petrosal.

Branches in the Neck.—The carotid branches run on the internal
carotid to its commencement at the common carotid, joining the
pharyngeal branches of the vagus and the sympathetic.

The pharyngeal, three or four, pierce the superior constrictor
to the mucous membrane of the upper pharynx.

The muscular, to the stylopharyngeus.

The tonsillitic, to the tonsil and soft palate, form the circulus
tonsillaris and join the palatine nerves.

The lingual are the two terminal branches. One supplies
the mucous membrane of the posterior third of the tongue
and the cireumvallate papillae; the other, to the side of the
tongue, joins the gustatory.

300 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The Pneumogastric Nerve

The tenth, vagus, or pneumogastric is both motor and sen-
sory. Its apparent origin is by twelve to fifteen filaments
from the groove between the olive and restiform bodies,
below, and in the line of the origin of the ninth; its deep origin
is from a nucleus in the lower part of the fourth ventricle. It
passes through the jugular foramen in the same sheath with
the spinal accessory, a partition separating them from the
ninth, and develops the ganglion of the root of the vagus. Emerg-
ing from the foramen, it forms the ganglion of the trunk of the
vagus.

The ganglion of the root (ganglion jugulare) is gray in color
and spherical, its diameter about two lines. It has branches
of communication with the accessory part of the spinal acces-
sory, with the petrous ganglion of the ninth, with the facial,
and with the superior cervical ganglion of the sympathetic.

The ganglion of the trunk (ganglion cervicale) is larger, of
a reddish color and cylindrical form. Its surface is crossed
by the accessory portion of the eleventh, and it communicates
with the hypoglossal, the upper two cervical, and the sym-
pathetic nerves.

The vagus then descends between the internal carotid artery
and the jugular vein to the thyroid cartilage, then between
the vein and the common carotid to the root of the neck.

On the right side the nerve crosses the first part of the sub-
clavian artery, descends behind the right innominate vein
and alongside of the trachea, and spreads out into the posterior
pulmonary plexus behind the root of the lung. Below, two
cords emerge from this plexus and ramify on the esophagus,
forming, with branches from the left, the esophageal plexus.
Again, forming a single trunk, the nerve descends on the back
of the esophagus to ramify’ on the posterior surface of the
stomach.

On the left side the nerve runs behind the left innominate
vein, between the left carotid and subclavian arteries, and
crosses the arch of the aorta. It forms the left posterior pul-
monary plexus, assists to form the esophageal plexus, and as
a single trunk descends on the front of the esophagus to ramify
on the anterior surface of the stomach.

. 1

THE PNEUMOGASTRIC NERVE Bol

Branches.—(a) In the jugular foramen: An auricular branch
(Arnold’s), from the jugular ganglion, receives a branch from

Fia. 62

Hypoglossal nerve.
Vagus nerve.
Glossopharyngeal nerve.

\ \yreahe..

Uh
ee >,

Hypoglossal nerve, cervical plexus, and their branches. (Gray.)

the petrous ganglion of the ninth, traverses a small canal in the
petrous portion of the temporal, crosses the aqueeductus Fallopii,

302 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

and communicates with the facial. It escapes through the
auricular fissure, then divides into a branch to the auricle,
and a second which joins the posterior auricular. A recurrent
branch from the jugular ganglion supplies the dura mater
in the posterior fossa.

(b) In the neck: A pharyngeal branch from the cervical
ganglion, deriving its fibers mainly from the spinal accessory,
crosses the internal carotid, and joins with the glossopharyngeal
and sympathetic in the pharyngeal plexus. This plexus supplies
the muscles and mucous membrane of the pharynx.

The superior laryngeal, from the lower ganglion, runs internal
to the internal carotid vessels, receiving branches from the
pharyngeal plexus and sympathetic, and divides into the
external and internal laryngeal nerves.

The eaternal runs beneath the sternothyroid to supply the
cricothyroid. It supplies the inferior constrictor, and sends
branches. to the pharyngeal plexus and superior cardiac nerve.

The internal branch pierces the thyrohyoid membrane to
supply the mucous membrane of the larynx, and by a long
branch joins a similar offset from the recurrent nerve behind
the ala of the thyroid cartilage. A twig supplies the aryte-
noideus.

The inferior or recurrent laryngeal on the right side arises
in front of the subclavian artery and winds backward around
that vessel; on the left it rises in front of the arch of the aorta
and winds backward around it. Both nerves ascend between
the trachea and esophagus, behind the common carotid and
inferior thyroid arteries, to the lower border of the cricoid
cartilage. They enter the larynx beneath the inferior con-
strictor, supplying all its intrinsic muscles excepting the crico-
thyroid, and join the superior laryngeal. Each gives off cardiac
nerves which join those from the vagus and sympathetic;
tracheal and esophageal branches, and one to the inferior con-
strictor.

The cervical cardiac nerves, two or three, are divided into
the superior, joining the cardiac branches of the sympathetic,
and the inferior, one on each side. The right lies in front of
the innominate artery, and joins the deep cardiac plexus. The
left, in front of the arch of the aorta, joins the superficial cardiac
plexus.

yo Ree a ae as i

THE HYPOGLOSSAL 300

(c) In the chest: The thoraeic cardiac branches, the right
from the trunk of the vagus and from the recurrent branch,
the left from the latter only. They join the deep cardiac
plexus.

Pulmonary nerves, two or three anterior, join the sympathetic
and form the anterior plexus on the root of the lung. The
posterior, larger and more numerous, join branches from the
second, third, and fourth thoracic ganglia to form the posterior
plexus. Offsets from these nerves accompany the bronchi
throughout the lung.

The esophageal, above and below the preceding. The lower
and larger branches come from the esophageal plexus.

_ (d) Gastric branches: These are the terminal branches of

the vagi. The right, to the posterior surface, join the celiac,
splenic, and left renal plexuses. The left, to the anterior
surface and lesser curvature, join the right nerve, the sympa-
thetic, and the hepatic plexus.

The Eleventh Pair

The eleventh, or spinal accessory, consists of a spinal portion
and an accessory part to the vagus. The latter part arises as
five or six filaments from the lateral tract of the medulla,
below the origin of the vagus. It sends some filaments into
the ganglion jugulare of the vagus, and joins that nerve below
the ganglion cervicale, being continued, for the most part,
into the pharyngeal and superior laryngeal branches.

The spinal portion arises from the lateral column of the cord
as low as the sixth cervical nerve, the fibers being connected
with the anterior horn of gray matter. This part then ascends,
between the posterior nerve roots and the ligamentum den-
ticulatum, through the foramen magnum, then out again by
the jugular foramen, lying in the sheath of the vagus, and
here communicates with the accessory portion. After its
exit from the skull it crosses the internal jugular vein and
pierces the sternomastoid to end in the trapezius.

The Hypoglossal

The twelfth, or hypoglossal, nerve arises by ten to fifteen
filaments from the groove between the pyramidal and olivary
23

354 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

bodies. The deep origin is from a nucleus in the floor of the
fourth ventricle. The filaments form two bundles which pierce
the dura separately and unite in the anterior condylar foramen.
The nerve descends behind the internal carotid artery and
internal jugular vein, closely bound to the vagus, then passes
forward between the artery and vein, and becomes superficial
below the digastric, curving around the occipital artery. It
now crosses the external carotid and lingual arteries, runs
between the mylohyoid and hyoglossus, communicates with -
the gustatory nerve, and, after piercing the genioglossus,
breaks up into filaments to the substance of the tongue.

Branches of communication pass to the vagus, superior
cervical ganglion of the sympathetic, to the loop between the -
first and second cervical, and to the gustatory nerves.

Branches of Distribution.—Descendens hypoglossi leaves the
nerve as it crosses the occipital artery, descends within or in
front of the carotid sheath, and, joining the ansa hypoglossi,
forms a loop from which the sternohyoid and thyroid and
both bellies of the omohyoid are supplied. Its origin may be
traced to the first and second cervical nerves.

The thyrohyoid branch crosses the great cornu of the hyoid
bone, to supply the muscle.

Muscular branches pass to the styloglossus, hyoglossus,
geniohyoglossus, and geniohyoid muscles.

Meningeal branches run to the posterior fossa, leaving the
nerve at the foramen.

THE SPINAL NERVES

The spinal nerves consist, on each side, of eight cervical,
twelve dorsal, five lumbar, five sacral, and one coccygeal,
in all thirty-one pairs, which arise from the cord by two roots,
anterior and posterior. The latter are the larger and are supplied
with ganglia. The suboccipital or first cervical nerve has no
ganglion. The two roots unite just beyond the ganglion,
and the resulting trunk divides into two divisions, anterior
and posterior, each containing fibers from both roots. The
posterior division divides into an external and an internal branch.
The anterior divisions in the dorsal region remain separate, but
elsewhere they unite into plexuses. They are larger than the
posterior. Each division is connected with the sympathetic.

j THE CERVICAL PLEXUS 355

The Cervical Nerves

Of the posterior divisions, that of the first or suboccipital
does not divide into an external and internal branch. It crosses
the atlas to the suboccipital triangle, and supplies the com-
plexus (in part), the obliqui, and posterior recti, a branch
joining the second nerve. Of the other nerves, the external
branches supply the splenius, transversalis colli, cervicalis
ascendens, and trachelomastoid. The internal, except that of
the second, run inward; those of the third, fourth, and fifth,
between the complexus and semispinalis, supply them and
the multifidus and the skin over the trapezius. The internal
branches of the sixth, seventh, and eighth run beneath the
semispinalis, and supply no cutaneous branches. The internal
branch of the second, known as the great occipital nerve, pierces
the trapezius and complexus (in part), supplies the latter,
and runs with the occipital artery supplying the back of the
head, and sends a branch to the small occipital.

The Cervical Plexus

The cervical plexus is formed by the anterior divisions of
the upper four cervical nerves, which emerge between the
scalenus -medius and rectus anticus major. It lies upon the
scalenus medius and levator anguli scapule, beneath the
sternomastoid. Each nerve except the first divides into a
branch for the nerve above and one for the nerve below. The
anterior division of the first (suboccipital) nerve grooves the
atlas beneath the vertebral artery, and joins the second, supply-
ing the rectus lateralis and recti antici. It communicates
with the sympathetic, vagus, and hypoglossal nerves.

Its branches are superficial and deep.

The superficial are divided into ascending and descending.

1. AscEnDING BrancHES.—(a) The superficialis colli, from the
second and third nerves, crosses the sternomastoid, and divides
under the platysma into two branches, an upper and a lower,
which ramify in the skin of the front of the neck, from the
maxilla to the stefnum.

(b) The auricularis magnus, from the second and _ third,
runs over the sternomastoid to the parotid region, and supplies

/

356 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

facial branches to the skin over the parotid, a mastoid branch
to the skin in that region, and auricular branches to the lobule
and back of the auricle. By these branches the nerve also
communicates with the facial and small occipital.

(c) The occipitalis minor, from the second and third (some-
times only the second), runs along the posterior border of the
sternomastoid to the head and supplies the scalp. It com-
municates with the great occipital and the great and posterior
auricular nerves, and gives a branch to the auricle.

Fia. 63

Neuraxis of Peripheral
Sensory Neurone

Spinal Ganglion

Dendrite of Anterior Horn of Gray Matter
Peripheral Sensory of Spinal Cord
Neurone

Neuraxis of Peripheral Motor Neurone

* set [ormmonnat Ganglion

Diagram to show the composition of a peripheral nerve trunk.
(B6hm and Davidoff.)

Nerve Trunk Neuraxis of

Sympathetic Neurone

2. DrescENDING BrancuEes.—These are the supraclavicular
nerves. They arise from the third and fourth cervical, and
divide into the suprasternal, supraclavicular, and supraacromial
branches, which descend between the trapezius and sterno-
mastoid to supply the skin over the regions indicated by their
names.

The deep branches consist of an eaternal and an internal
series.

The EXTERNAL include muscular, to the sternomastoid
(from the second); trapezius, scalenus medius, and levator
anguli scapulee (from the third and fourth), and communicating,

2

ee EE

ae a + ;
Se Es Se

es

THE BRACHIAL PLEXUS 357

which join the spinal accessory within the sternomastoid and
trapezius, and also between these two muscles.

The INTERNAL are: Communicating, from the loop between
the first and second, to the vagus, hypoglossal, and sympa-
thetic, and a branch from the fourth to the fifth.

Muscular, to the lateral and anterior recti muscles (from
the first and second).

Communicantes hypoglossi, generally two, one from the second
and one from the third, pass under or over the internal jugular
to join the descending branch from the hypoglossal nerve.

Phrenic, from the third, fourth, and fifth, descends on the
scalenus anticus, then between the subclavian artery and
vein, and crosses the internal mammary artery. It then crosses
in front of the root of the lung and runs between the peri-
cardium. and mediastinal pleura to the diaphragm; it com-
municates with the sympathetic, descendens noni, and the
nerve to the subclavius. The right is deeper than the left. It
runs external to the innominate vein and superior vena cava.
The left crosses the front of the aortic arch and the left vagus.
Both phrenies supply the diaphragm, pleura, and pericardium.
Filaments from the right, with the phrenic branches of the
solar plexus, form a ganglion, which sends branches to the
suprarenal capsules and inferior vena cava and to the hepatic
plexus; on the left side there is no ganglion.

The Brachial Plexus

The brachial plexus is formed by.the anterior divisions of
the lower four cervical and first dorsal, as follows: The fifth
and sixth form an upper; the seventh, a middle; and the eighth
cervical with first dorsal, a lower trunk. Each of these trunks
then separates into an anterior and a posterior branch.

The anterior branches of the upper and middle trunks form
the outer cord of the plexus; the anterior branch of the lower,
the inner cord; of the posterior cord it is variously stated that
the posterior branches of all three trunks form it, or that the
posterior branches of the upper and middle trunks form it,
while the posterior branch of the lower trunk joins the musculo-
spiral nerve. It is altogether a matter of dissection.

The plexus is at first between the anterior and middle scaleni,
then above and external to the subclavian artery. It passes

308 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

behind the clavicle and subclavius, lying on the subscapularis
and serratus magnus. The cords lie external to the first part
of the axillary artery, but on three sides of the second part
of that vessel.

BRANCHES ABOVE THE CLAVICLE.—A branch from the fifth
joins the phrenic, and muscular branches supply the scaleni,
longus colli, rhomboidei, and subclavius. The branch to the

Fia. 64

From 4th

V Cervical

VIL Gffrical

Branches to Longus
Colli and Sealeni >

VIIL Cervical IS
Anterior division \)
of Middle Trunk peat Led

I Dorsal

Circumflex
Lower Trunk 7 Se : >

Posterior division of Middle Trunk

External Anterior Thoracie
Posterior division of Upper Trunk
Upper Sub-seapular

Middle and Lower
Sub-scapular

Posterior Thoracie

Anterior division of Lower Trunk
Posterior division of Lower Trunk
Internal Anterior Vhoracic

Lesser Internal Cutaneous Musculo-cutaneous
Internal Cutaneous

Ulnar Median

Musculo-spiral

Plan of the brachiai plexus. (Gray.)

subclavius, from the trunk formed by the fifth and sixth cervical,
crosses the subclavian artery, its third part, and sends a branch
to the phrenic nerve.

The posterior thoracic nerve, from fifth and sixth cervical,
runs out of the scalenus medius and descends behind the clavicle
upon the serratus magnus, which it supplies.

The suprascapular nerve, from the fifth and sixth, enters

the supraspinous fossa by the notch, supplies an articular —

|
:
|

a

d
7
»

THE BRACHIAL PLEXUS 309

branch and one to the muscle, also a branch to the infraspinous
fossa and muscle.

BRANCHES BELOW THE CLAVICLE.—The three cords give
off the following nerves: The outer, the musculocutaneous,
outer head of the median, external anterior thoracic; the inner,
the internal anterior thoracic, inner head of median, internal
and lesser internal cutaneous, and the ulnar; the posterior,
the musculospiral and circumflex, and subscapular.

The anterior thoracic nerves supply the pectoral muscles.
The external comes off from the outer cord, crosses the axillary
artery, and gives a branch to the inner nerve, and ends in the
pectoralis major, to which it is distributed. The internal
comes off from the inner cord, runs forth between the artery
and vein, and joins the branch from the external, forming
a loop around the artery. It supplies the pectoralis minor, a
portion of it passes on through this muscle to the great pectoral,
completing its nerve supply.

The subscapular: The wpper (from the posterior branch of
the upper trunk) supplies the subscapularis at its upper part;
the middle or long accompanies the subscapular artery to the
latissimus dorsi; and the lower (from posterior cord) supplies
the subscapularis, entering its axillary margin, and teres major.
_ The internal cutaneous (from inner cord), on the inner side
of the axillary artery, divides at the middle of the arm into
an anterior branch, crossing over or under the median basilic
vein, which supplies the forearm as far as the wrist, and a
posterior, which winds above the inner condyle to back of
humerus, and runs to lower part of forearm. ‘This nerve com-
municates with the lesser nerve and the ulnar, and supplies
the skin over the biceps.

The lesser internal cutaneous (of Wrisberg), from the inner
cord, runs behind and then internal to the axillary vein and
joins the intercostohumeral nerve. It then runs along the
inner side of the brachial artery, and supplies the skin as far
as the olecranon and internal condyle.

The intercostohumeral bears a complementary relation,
in point of size, to the lesser nerve, and may even replace it
altogether.

The circumflex nerve, from -the posterior cord, is at first
behind the axillary artery. It winds back through the space
bounded by the triceps, humerus, and the two teres muscles,

360 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

gives a filament to the shoulder-joint, and divides into two
branches, an wpper and a lower. The former winds around
the humerus to the anterior border of the deltoid, supplying
it and the skin, and the latter supplies the skin over the lower
two-thirds of the deltoid as well as. the muscle, and gives a
branch to the teres minor, upon which a ganglion is developed.

The external or musculocutaneous nerve arises from the
outer cord opposite the lower border of the pectoralis minor,
and runs through the coracobrachialis and over the brachialis
anticus to pierce the fascia at the outer border of the biceps,
a little above the elbow. It then runs behind the median
cephalic vein and divides into two branches, anterior and
posterior.

In the arm it supplies the three muscles mentioned above,
a filament to the elbow-joint, and one to the humerus.

The anterior branch crosses the radial artery at wrist and
joins a branch of the radial nerve and the palmar cutaneous
branch of the median. It supplies the skin over the radius
and twigs to the artery. The posterior branch descends along
the back of the forearm to the wrist and joins branches of the
radial and musculospiral nerves.

The median nerve arises by two roots, an outer from the
outer cord and an inner from the inner cord, which unite in
front of or to the outer side of the axillary artery. It lies to
the outer side of the brachial artery above and crosses over
(or under) it to its inner side. It passes between the two heads
of the pronator teres, running on the flexor profundus and
beneath the annular ligament into the hand. At the wrist
it lies behind and to the ulnar side of the palmaris longus.

BRANCHES.—1. In the arm, none.

2. In the forearm it supplies all the superficial flexor muscles
except the flexor carpi ulnaris; some filaments to the elbow-
joint; some of the filaments to the muscles may come off a
little above the elbow.

The anterior interosseous nerve comes off a little below the
elbow and runs along the interosseous membrane with the
artery of that name. It supplies the flexor longus pollicis
and the outer half of the flexor profundus digitorum muscles,
between which it lies, and also the pronator quadratus, in
which it ends.

The palmar cutaneous branch pierces the fascia above the

THE BRACHIAL PLEXUS 361

annular ligament, and supplies the skin over the ball of the
thumb and the palm. It communicates with branches of the
ulnar and external cutaneous nerves.

3. In the palm the nerve lies on the flexor tendons,
covered by the annular ligament, and becomes larger and
reddish in color. It divides into two branches—the eaternal,
supplying some of the muscles of the thumb and digital branches
to the thumb and index finger; and the internal, supplying
digital nerves to the index, middle, and ring fingers.

The muscular branches supply the abductor, opponens,
and outer head of the flexor brevis pollicis. The first digital,
with the second, supplies the thumb, the former joining a
branch of the radial. The third, along the radial side of the
index finger, supplies it and the first lumbricalis. The fourth
supplies the adjacent sides of the index and middle fingers
and the second lumbricalis. The fifth, to the adjacent sides
of the middle and ring fingers, joins a branch of the ulnar.
Each digital nerve divides at the tip of the finger into a branch
to the pulp and one to the matrix of the nail. At the base
of the first phalanx each sends a branch to the back of the
second and third phalanges.

The ulnar nerve from the inner cord runs internal to the
axillary and brachial arteries as far as the middle of the arm.
It then passes on the inner head of the triceps to the groove
between the olecranon and internal condyle with the inferior
profunda artery, and runs between the two heads of the flexor
carpi ulnaris with the posterior ulnar recurrent artery, lying
beneath the muscle above and to the radial side of it below.
In the lower two-thirds of the forearm the ulnar artery is
external. The nerve then crosses the annular ligament between
the artery and pisiform bone, and divides into a SH Rial
and a deep branch.

BrancHEs.—1. In the arm, none.

2. In the forearm, several articular to the elbow. Muscular,
-to the flexor carpi ulnaris and inner half of the flexor profundus.
Two cutaneous by a common trunk. One joins a branch of
the internal cutaneous, and the other, the palmar cutaneous,
runs on the ulnar artery to the palm, joining branches of the
median nerve.

The dorsal cutaneous comes off about two inches above the
wrist, runs backward beneath the flexor carpi ulnaris, and

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Deep nerves of the front of the right arm, (Testut.)

THE BRACHIAL PLEXUS 363

supplies dorsally the little and inner half of the ring finger.
The latter communicates with the contiguous branch of the
radial.

3. In the palm are the superficial and deep branches. The
former supplies the skin and palmaris brevis and digital branches
to the little and inner half of the-ring fingers, the latter join-
ing a branch of the median. The latter, passing between flexor
brevis and abductor minimi digiti, supplies all the muscles
of the hand except those supplied by the median nerve, and
sends filaments to the wrist-joint.

The musculospiral nerve is from the posterior cord and runs
behind the axillary and brachial vessels, and, later, in the
musculospiral groove with the superior profunda artery, pierces
the external intermuscular septum to the anterior aspect of
_ the arm, then between the brachialis anticus and supinator
longus. In front of the outer condyle it divides into the radial
and posterior interosseous nerves.

BrancuEs.—Muscular and cutaneous.

Muscular Branches.—These leave the nerve, as their names
imply, at the inner, posterior, and outer parts of the arm.
The internal supplies the inner and middle heads of the triceps;
the posterior supplies the outer head of the triceps and the
anconeus; the external supplies the supinator longus, extensor
carpi radialis longior, and the brachialis anticus.

Cutaneous Branches.—The internal arises before the nerve
enters the musculospiral groove, supplies the inner side of the
posterior aspect of the arm; the two external pierce the outer
head of the triceps close to its origin. The wpper supplies the
lower part of the upper arm; the lower, the lower half of the
arm, forearm, and wrist dorsally, joining the posterior branch.
of the musculocutaneous.

The radial nerve is a purely sensory nerve, it is sversapal
by and runs parallel with the supinator longus, finally runs
backward beneath its tendon, just above the wrist, pierces
the fascia, and divides into two branches. Of these, the external
supplies the radial side and ball of the thumb, and joins a
branch of the musculocutaneous; the internal, after communi-
eating with the musculocutaneous, supplies dorsally digital
branches to the thumb and index, index and middle, middle
and outer half of the ring fingers.

This last joins with the contiguous branch of the dorsal

364 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

cutaneous of the ulna, and they all terminate at the base of the
second phalanx.

The posterior interosseous passes between the planes of the
supinator brevis, around the outer side of the neck of the
radius, and runs beneath the superficial muscles on the back
of the forearm and on the lower part of the interosseous mem-
brane. It supplies all the muscles of the back and outer part
of the forearm except the supinator longus, extensor carpi
radialis longior, and the anconeus, and terminates at the
wrist in a ganglion from which are supplied the carpal liga-
ments and joint.

The Dorsal Nerves

The posterior divisions in the dorsal region: The external
branches increase in size from above downward, pierce the
longissimus dorsi to supply the erector spine group, and those
of the lower six, the skin. The internal branches of the six
upper supply the multifidus and semispinalis dorsi and the
skin. The six lower internal supply the multifidus, but not
the skin.

The Anterior Divisions of the Dorsal Nerves

First Dorsal.—The anterior division in part joins the brachial
plexus, and the remainder of the nerve forms the first inter-
costal, which has no lateral cutaneous branch.

The UppER stIx are called the pectoral intercostal nerves,
and lie below the vessels. At first they run between the pleura
and the external intercostal muscles, then between the two
planes of muscles to the middle of the rib, here giving off the
lateral cutaneous nerves. The nerves now enter the substance
of the internal intercostals as far as the cartilages, where they
lie between the muscles and the pleura. Finally they cross
the internal mammary vessels and the triangularis sterni,
pierce the internal intercostals and pectoralis major, and end
in the skin of the chest, as the anterior cutaneous nerves of the
thorax. .

Branches.—Muscular, to the intercostals, triangularis,
levatores costarum, and serratus posticus superior.

The lateral cutaneous are given off about midway to the

THE LUMBAR NERVES 365

sternum, pierce the serratus magnus and external intercostals,
and each divides into two branches, anterior and posterior.

The anterior runs to the skin over upper part of the external
oblique, mamma, and skin; the posterior, to the skin over the
scapula and latissimus dorsi.

The lateral cutaneous of the second dorsal crosses to the
arm, joins the nerve of Wrisberg, pierces the fascia, and supplies
the skin of the upper half of the inner and back part of the
upper arm, joining the cutaneous branch of the musculospiral
nerve. This nerve is generally called the intercostohumeral.
It has no anterior division.

The LOWER six, or abdominal intercostals, run from the
intercostal spaces behind the cartilages, between the internal
oblique and transversalis, to the rectus, which they enter.
They supply the intercostals, serratus posticus inferior, abdom-
inal muscles, and end in the skin, as the anterior cutancous
nerves of the abdomen.

The lateral cutaneous branches have a similar distribution
to those in the chest.

The LAST DORSAL nerve is altogether abdominal. It crosses
the quadratus lumborum and runs into the abdominal wall
like the lower intercostals. It communicates with the ilio-
hypogastric and with the first lumbar nerve (dorsolumbar).
Its lateral cutaneous branch supplies the skin of the forepart
of the gluteal region as low as the great trochanter.

Each dorsal nerve is joined by short communicating branches
from the sympathetic.

The Lumbar Nerves

The Posterior Division.—In the lumbar region the internal
branches end in the multifidus. The eaternal supply the inter-
transverse muscles and erector spine, and the upper three
a portion of the skin over the gluteal region.

The Anterior Divisions of the Lumbar Nerves.—The first unites
with a branch from the last dorsal, the dorsolumbar nerve,
and then proceeds, together with the second, third, and fourth,
to form the lumbar plexus. The fifth joins the sacral plexus.
They are joined by the sympathetic filaments, and furnish
branches to the psoas and quadratus muscles.

366 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The Lumbar Plexus

The lumbar plexus is formed in the substance of the psoas
muscle, in the following manner: Each of the first four lumbar
nerves divides into an wpper and a lower branch. Just before
dividing the first receives the dorsolumbar nerve, and the third
and fourth send each a branch to the nerve below.

The upper branch of the first subdivides into the zlohypo-
gastric and wliinguinal nerves. The lower branch of the first
passes downward and subdivides into two branches, one of
which unites with the wpper branch of the second to form the
genttocrural nerve. The other unites with the lower branch
of the second to form a cord. This cord passes downward,
and gives off the eaternal cutaneous nerve and a branch to
the obturator, after which it unites with the upper branches
of the third and fourth to form the anterior crural nerve. The
lower branches of the third and fourth unite to form the
obturator nerve.

The iliohypogastric escapes at the upper part of the psoas,
crosses the quadratus, pierces the transversalis at the iliac
crest, and divides, between it and the internal oblique, into
two branches. The zliac branch supplies the skin over the
glutei, behind the lateral cutaneous of the last dorsal; the
hypogastric branch communicates with the ilioinguinal, and
pierces the oblique muscles to supply the skin of the pubic
and hypogastric regions.

The ilioinguinal crosses the quadratus and iliacus below
the preceding, pierces the transversalis, communicating with
the iliohypogastric, and runs in the inguinal canal, supplying
the skin of the groin, scrotum, and penis (the labium in the
female).

The genitocrural runs downward through and on the psoas
muscle, and divides some distance above Poupart’s ligament
into a genital and a crural branch. The former lies on the
external iliac artery, sending filaments around it, and runs
with the cord through the inguinal canal to the cremaster
muscle; in the female it runs on the round ligament. The
crural branch runs under Poupart’s ligament into the thigh,
sending filaments around the femoral artery, and lying super-
ficial to the artery in the femoral sheath. It supplies the
skin of the upper thigh, and joins the middle cutaneous.

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THE LUMBAR PLEXUS 367

The external cutaneous crosses the iliacus and enters the
thigh through the notch below the anterior superior spine of
the ilium, superficial to the sartorius, dividing into an anterior
and a posterior branch. The former runs in a canal within the
fascia lata, and becomes cutaneous four inches below Poupart’s
ligament. It supplies the front and outer part of the thigh
to the knee, sometimes joining in the patellar plexus. The
posterior branch supplies the skin of the outer and back part
of the thigh halfway to the knee.

The obturator nerve emerges from the inner border of the
psoas at the pelvic brim. It runs above the obturator vessels
to escape at the upper part of the obturator foramen, dividing
into two branches separated by the adductor brevis. The
anterior runs beneath the pectineus and adductor longus,
joining at the lower part of the latter with branches of the
long saphenous and internal cutaneous nerves to form a plexus.
A branch supplies the hip-joint; muscular branches to gracilis
and adductor longus, sometimes to the adductor brevis and
pectineus; the terminal branch to the femoral artery.

The posterior branch pierces the obturator externus and
runs behind the adductor brevis on the adductor ‘magnus,
and supplies these muscles (the adductor magnus only in
part). A branch to the knee-joint pierces the magnus, lies
on the popliteal artery, sending branches to it, and _ pierces
the ligamentum Winslowii to supply the synovial membrane.

The accessory obturator is inconstant; when present it arises
by branches from the second, third, and fourth nerves, or is
a branch of the obturator. It runs along the inner border
of the psoas, and, crossing the pubes, divides beneath the
pectineus into three branches—one to the anterior branch
of the obturator, another to the hip-joint, and a third to the
pectineus. It is not constant.

The anterior crural nerve is the largest branch of the lumbar
plexus. It enters the thigh between the psoas and iliacus,
external to the femoral artery, and divides into an anterior
(mainly cutaneous) and a posterior (mainly muscular) portion.

BRANCHES.—Within the abdomen, three or more branches
to the iliacus, and a branch to the femoral artery.

ANTERIOR Portion.—(a) The middle cutaneous pierces the
- fascia lata four inches below Poupart’s ligament, and divides into
two branches which run on the front of the thigh to the patella.

368 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

It joins the crural branch of the genitocrural and the internal
cutaneous nerves.

(b) The internal cutaneous crosses the femoral artery and
divides into two branches, anterior and posterior. It supplies
several cutaneous filaments which follow the course of the
long saphenous vein, one reaching to the knee. The antervor
branch runs to the knee, perforating the fascia lata low down,
and, crossing the patella to its outer side, communicates with
a branch of the long saphenous nerve. The posterior branch
runs along the posterior border of the sartorius, communicates
with the internal saphenous nerve, and supplies the skin of
the inner side of the thigh (lower part) and leg. It perforates
the fascia lata at inner side of knee. It also joins branches
of the obturator beneath the fascia.

(c) Branch to the pectineus passing behind the femoral
vessels.

(d) Branches to the sartorius from the middle cutaneous.

PosTERIOR Portion.—(a) Branch to the rectus femoris; also
sends a twig to the hip-joint.

(b) Branch to the vastus externus.

(c) Branches to the crureus: One of these sends a filament
to the knee-joint.

(d) Branch to the vastus internus accompanies the saphenous
nerve and sends a filament to the knee-joint.

(e) The internal saphenous nerve accompanies the femoral
vessels, being at first external to and later crossing the artery.
It then runs beneath the sartorius to the inner side of the
knee, pierces the fascia, and accompanies the saphenous vein
along the inner side of the leg. Passing in front of the inner
ankle, it ends on the inner side of the metatarsus. It commu-
nicates with the obturator and internal cutaneous nerves.

Branches supply the skin of the leg. The terminal branches
communicate with the musculocutaneous, and a patellar branch
spreads out over the knee and joins in the patellar plexus.

The Sacral and Coccygeal Nerves

The Posterior Divisions.—In the sacral region, of the wpper
three, the internal branches end in the multifidus spine, and
the eaternal anastomose with the fourth sacral and last lumbar.
They send off filaments over the great sciatic ligament, finally
ending in the skin by two branches.

-

THE SACRAL PLEXUS 369

The last two do not divide, but join the coccygeal nerve.

The posterior division of the coccygeal nerve ends with the
above, and supplies the skin over the coccyx.

The Anterior Divisions.—The anterior division of the fifth
lumbar receives a branch from the fourth, and, under the
name of the /wmbosacral cord, joins the first sacral.

The anterior divisions of the first four sacral nerves escape
by the anterior sacral foramina; the fifth, between the sacrum
and coecyx; all join with filaments from the sympathetic.

The first three, with a branch from the fourth, enter into
the formation of the sacral plexus.

The fourth, its remaining portion, sends branches to the
bladder and adjacent viscera, and supplies the levator ani,
coccygeus, external sphincter (see Perineal and the Hemor-
rhoidal Nerve), and skin of the perineum. It also sends a
branch to the fifth sacral. The visceral branches unite with
occasional branches from the third sacral and with the sym-
pathetic. ,

The fifth sacral pierces the coccygeus, supplying it and the
skin over the coceyx. Branches from the fourth sacral and
the coccygeal nerve join it.

The anterior division of the coccygeal nerve, very small,
pierces the coceygeus and sacrosciatic ligaments, and termi-
nates by uniting with the fifth sacral.

The Sacral Plexus

The sacral plexus is formed by the anterior divisions of the
first, second, third, and part of the fourth sacral nerves, together
with the lumbosacral cord.

The lumbosacral cord, with the first, second, and part of the
third sacral nerve, is continued into the upper great branch
of the plexus, and the remainder of the plexus forms the lower
or smaller branch.

Branches.—Besides these two principal branches, which
are, respectively, the great sciatic and the pudic nerves, the
upper nerves of the plexus give off the nerves of the pyriformis,
quadratus, femoris, obturator internus, and gemelli, as well
as the superior and inferior gluteal, small scvatic, and a per-
. forating cutaneous branch.

24

370 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The muscular branch to the obturator internus crosses the
spine of the ischium and enters the small sciatic foramen to
the inner surface of the muscle. It also supplies the swperior
gemellus. That to the quadratus femoris runs beneath the
tendon of the obturator internus, and supplies also the inferior
gemellus and hip-joint. Lastly, the py yriformis receives several
filaments from the sacral nerves previous to the formation
of the plexus.

The superior gluteal emerges above the pyriformis, through
the great sciatic notch, and divides into an upper branch,
to the gluteus medius, and a lower, larger branch, which sup-
plies both the medius and minimus, piercing the latter to end
in the tensor vaginee femoris. It arises from the lumbosacral
cord and first sacral nerve.

The inferior gluteal emerges below the pyriformis, dividing
into numerous branches for the gluteus maximus. It sends
a branch to join the small sciatic. It arises from the lumbo- |
sacral cord and first and second sacral nerves.

The small sciatic is purely sensor; it appears below the
pyriformis, and runs beneath the gluteus maximus upon the
great sciatic nerve, thence beneath the fascia lata, which it
pierces just below the knee. It communicates with the external
saphenous nerve. It arises from the second and third sacral
nerves.

Branches.—Cutaneous, to the calf of the leg, to the inferior
gluteal region, and to the back and inner part of the thigh
(femoral cutaneous); and the inferior pudendal nerve, derived
below the tuber ischii, to the scrotum or labium majus and
the skin of the upper and inner part of the thigh.

The perforating cutaneous nerve, from the fourth sacral
nerve, pierces the great sciatic ligament and turns over the
lower border of the gluteus maximus to supply the skin over
its lower part. |

The pudic nerve emerges between the coccygeus and pyri-
formis, and crosses the ischial spine to re-enter the pelvis by

*the lesser sacrosciatic foramen. It divides, in the ischiorectal
fossa, into the inferior hemorrhoidal, perineal, and dorsal nerve
of the penis or clitoris.

The inferior hemorrhoidal supplies the external sphincter
(in part) and the skin of the back part of the perineum, com-
municating with the pudendal and perineal nerves.

THE SACRAL PLEXUS | 371

The perineal runs in a sheath of the obturator fascia along
the outer wall of the ischiorectal fossa, and divides into swper-
ficial and deep branches. The latter supply the external sphincter
(in part, see Fourth Sacral) and the muscles of the perineum,
sending a branch to the mucous membrane of the urethra,
which pierces the corpus spongiosum.

The superficial branches are external and internal. The
former supplies the scrotum and inner side of the thigh, and
the latter runs nearer to the middle line and supplies the skin
of the scrotum. Both the superficial perineal nerves communi-
cate with the pudendal and hemorrhoidal branches, and in
the female end in the labia majora.

The dorsal nerve of the penis (in the female, of the clitoris)
accompanies the pudic artery, and runs along the dorsum to
the glans. It supplies branches to the constrictor urethre
to the integument of the penis, and to the corpus cavernosum.
On the penis it receives branches from the sympathetic. In
the female the analogue of this nerve is smaller, with a like
distribution.

The great sciatic nerve is the largest nerve in the body, and
includes fibers from the greater part of the sacral plexus. From
the lower border of the pyriformis it descends on the gemelli,
obturator internus, and quadratus, then on the adductor
magnus, being covered by the gluteus maximus and long head
of the biceps, and accompanied by the small sciatic nerve and
the sciatic artery. It divides at the lower third of the thigh
into the external and internal popliteal nerves. It supplies the
biceps, semitendinosus and semimembranosus, adductor magnus
(in part), and hip-joint (in part).

The internal popliteal nerve is the larger branch of bifurca-
tion of the great sciatic. It runs along the middle of the popliteal
space to the lower border of the popliteus, where it becomes
the posterior tibial. It is at first external to, then behind,
and lastly internal to, the popliteal artery.

Branches.—Three articular, one accompanying the azygos
articular artery, and one each to the upper and lower articular
arteries on the inner side of the knee-joint.

Muscular.—One to each head of the gastrocnemius, to the
plantaris, to the soleus, and to the popliteus. The latter
gives filaments to the tibia and interosseous membrane, and
turns beneath the lower border of the muscle.

372 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

-Cutaneous.—The tibial or popliteal communicating. It
runs between the two heads of the gastrocnemius, pierces the
fascia about halfway down the calf, and receives the peroneal
communicating nerve from the external popliteal. It then
runs in company with the short saphenous vein, along the
outer border of the tendo Achillis and below the outer malleolus,
to end in the skin of the outer side of the foot and little toe,
communicating with the musculocutaneous nerve.

The posterior tibial nerve is the continuation of the internal
popliteal from the lower margin of the popliteus. It runs
down between the superficial and deep layers of muscles and
is successively internal, behind, and external to the artery,
and divides between the inner ankle and heel into the two
plantar nerves.

Branches.— Articular, to the ankle.

Muscular.—One each to the tibialis posticus, flexor longus
digitorum, flexor longus pollicis, and the soleus.

A cutaneous branch pierces the internal annular ligament
to supply the skin of the heel and back part of the sole.

The internal plantar nerve runs beneath the abductor pollicis,
then between it and the flexor brevis pollicis, and divides
into its digital branches. It corresponds to the median in the
hand.

Branches.—Muscular, to the abductor pollicis and flexor
brevis digitorum.

Cutaneous, to the skin of the sole.

Digital branches as follows: The first; to the inner side of
the great toe, supplies the flexor brevis pollicis; the second,
to the great and second toes, supplies the first lumbricalis;
the third, to the second and third toes, supplies the second
lumbricalis; and the fourth, to the third and the inner side
of the fourth toe, communicating with the external plantar.
Each digital nerve supplies cutaneous and articular branches
and terminates as in the hand.

The external plantar runs between the flexor accessorius
and the flexor brevis digitorum, dividing between the latter
and the abductor minimi digiti into a superficial and a deep
branch. Before dividing it supplies the flexor accessorius and
abductor minimi digiti. It corresponds to the ulnar in the hand.

The superficial gives a digital branch to the outer side of
the little toe, which supplies its short flexor and sometimes

i ae Ye 4

=

THE SACRAL PLEXUS 373

also the interossei of the fourth space, and another digital
branch to the adjacent sides of this toe and the fourth.

The deep branch dips under the accessorius and flexor muscles,
and supplies all the dorsal and plantar interossei except, occa-
sionally, those of the fourth space; it also supplies the outer
two lumbricales, the adductor pollicis, and the transversus
pedis.

The external popliteal or peroneal nerve runs between the
biceps muscle and outer head of the gastrocnemius, turns
round the fibula just below its head and beneath the peroneus
longus, and divides into the anterior tibial and the musculo-
cutaneous nerves.

Branches.—Articular, with the upper and lower external
articular arteries, and occasionally a recurrent articular branch,
with the recurrent tibial artery, reaches the joint.

Cutaneous, two in number, supply the skin of the outer and
back part of the leg; and another, arising from its lower part,
the peroneal communicating, crosses the outer head of the
gastrocnemius and passing obliquely downward joins the
popliteal communicating to form the short saphenous nerve.

The musculocutaneous nerve runs between the extensor
longus digitorum and the peronei, and pierces the fascia at
the lower part of the leg, dividing into two branches, external
and internal, for the toes.

Branches.— Muscular, to the peroneus longus and _ brevis;
cutaneous, to the lower part of the leg.

The terminal branches: . Of these, the internal runs on the
dorsum of the foot and supplies the adjacent sides of the second |
and third toes and the inner side of the great toe. It com-
municates with the long saphenous and anterior tibial nerves.

The eaternal supplies the fourth toe, together with the con-
tiguous sides of the third and fifth. It communicates with
a branch of the short saphenous nerve.

The anterior tibial nerve, from between the peroneus longus
and fibula, runs along the front of the interosseous membrane
with the artery to the ankle, where it divides into an external
and an internal branch. It is at first external, then in front,
and below again external to the artery.

Branches.— Muscular, to the tibialis anticus, extensor longus
digitorum, extensor proprius, and the peroneus tertius; artic-
ular, to ankle; and its terminal branches. Of these—

374 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The external runs under the extensor brevis digitorum, and
supplies it as well as the neighboring joints.

The internal accompanies the dorsal artery of the foot to
the first interosseous space, and supplies the skin of the great
and second toes, joining a branch of the musculocutaneous.
Both these nerves send interosseous branches to the metatarso-
phalangeal joints.

THE SYMPATHETIC NERVOUS SYSTEM

The sympathetic nervous system consists of a series of ganglia,
cords, and plexuses, with their communicating and distrib-
uting nerve fibers. Its nerves supply all the viscera and the
coats of the bloodvessels.

There are two principal gangliated cords, lying one on each
side of the spine from the base of the skull to the coccyx. They
consist of a series of ganglia connected by short single or
double cords. The number of the ganglia corresponds 1 in general
to that of the vertebre in the several regions, except in the
neck, where there are but three.

Below, these cords end on the front of the coceyx by a loop
on which is the ganglion impar, and above they are connected
with the carotid plexus in the carotid canal.

The ganglia are connected with the spinal nerves by gray and
white fibers, the former passing from the ganglia to the spinal
nerves, and the latter vice versa. The ganglia are also connected
together by gray and white fibers, the latter being continuous
with the fibers of the spinal nerves prolonged to the ganglia.

There are three great plexuses, consisting of nerves and
ganglia. They are single and lie in front of the spine in the
thoracic, abdominal, and _ pelvic regions, and each is named,
from above downward, the cardiac, epigastric, and hypogastric
plexus.

THE SYMPATHETIC NERVES OF THE NECK

The cervical part consists of three ganglia, named superior,
middle, and inferior, on each side.
The superior ganglion, opposite the second and third cervical

ee

THE SYMPATHETIC NERVES OF THE NECK 375

vertebree, is reddish gray in color, fusiform in shape, and lies
on the rectus anticus major behind the internal carotid vessels.

Branches.—An ascending branch runs alongside the internal
carotid artery, and in the canal separates into an outer division,
forming the carotid plexus, and an inner, forming the cavernous
plexus. ¥

The carotid plexus lies external to the artery. It sends one
or more filaments to the sixth nerve as it lies alongside the
artery, and some to the Gasserian ganglion; to the spheno-
palatine ganglion it sends the large deep petrosal nerve, which
joins the large superficial petrosal to form the Vidian; it also
sends the small deep petrosal, which communicates with
Jacobson’s nerve by joining the tympanic plexus.

The cavernous plexus, in the cavernous sinus, lies below and
internal to the internal carotid. It sends a branch to the
third nerve, one to the fourth, several to the ophthalmic divi-
sion of the fifth, the sympathetic root to the ophthalmic ganglion
and filaments to the pituitary body.

Both these plexuses supply terminal filaments which form
plexuses on the ophthalmic and cerebral arteries and sub-
branches. © :

A descending branch to the middle cervical ganglion.

External branches to the first four spinal nerves, to the
ganglia of the vagus, the petrous ganglion of the glossopharyn-
geal, and to the hypoglossal.

Three internal branches, viz., pharyngeal. laryngeal, and
the superior cardiac nerve. The pharyngeal runs to the pharynx
and unites with the branches of the ninth and tenth cranial,
forming the pharyngeal plexus.

The laryngeal branch joins the superior and external laryn-
geal nerves.

The superior cardiac nerve descends on the longus colli behind
the common carotid sheath, and crosses the inferior thyroid
artery and recurrent nerve.. It rises from the upper ganglion,
and receives filaments from a communicating branch between
it and the middle ganglion. On the right side it crosses the
subclavian, and runs along the innominate artery to join
the deep cardiac plexus behind the aorta. It receives many
branches from the vagus and sympathetic. The left descends
along the left carotid to enter the superficial cardiac plexus
in front of the aorta.

376 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The anterior branches of the superior ganglion pass to the
bloodvessels, viz., to the external carotid and its branches—
forming gangliated plexuses named lingual, facial, temporal,
meningeal, ete. They communicate with the submaxillary
and otic ganglia and with the geniculate ganglion of the facial
nérve (external petrosal nerve). .

The middle (thyroid ganglion) lies in front of the sixth cervical
vertebra, on the inferior thyroid artery. It is connected with

the superior and inferior ganglia and with the fifth and sixth —

cervical nerves. It also gives off the thyroid branches and
middle cardiac nerves.

The thyroid branches run along the inferior thyroid artery
to the gland, and join the recurrent and external laryngeal
nerves. On the artery they connect with the upper cardiac
nerve.

The middle cardiac nerve (deep or great), on the left side,
descends between the carotid and subclavian arteries to join
the deep cardiac plexus; on the right it runs in front of or behind
the subclavian artery, then along the trachea, to join the
deep cardiac plexus. In its course it joins the recurrent branch
of the vagus and the upper cardiac nerve.

The inferior cervical ganglion lies between the transverse

process of the seventh cervical vertebra and the neck of the °

first rib, behind the vertebral artery, and communicates with
the seventh and eighth cervical nerves by gray rami communi-

cantes. It sends branches to the middle cervical; one of these ~

forms a loop around the subclavian artery, called the ansa
subclavii (Vieussenii), also the first thoracic ganglion (these
branches may be derived from the middle cervical ganglion),
and some along the vertebral artery, forming a plexus. It also
sends off the inferior cardiac nerve. This descends behind the
subclavian artery and along the trachea, and, after communi-
cating with the middle cardiac and recurrent nerve, ends in the
deep cardiac plexus.

THE SYMPATHETIC NERVES OF THE THORAX

In the thoracic portion ganglia lie in a line along the heads
of the ribs, beneath the pleura and in front of the intercostal
vessels. They communicate with the spinal nerves. The

THE SYMPATHETIC PLEXUSES 377

upper five or six supply the aorta, the vertebree and their
ligaments, and enter into the posterior pulmonary plexus.
The lower six or seven unite to form the splanchnic nerves.
The large splanchnic arises from the fifth or sixth to the
ninth or tenth, descends obliquely along the spine, and pierces
the crus of the diaphragm to end in the semilunar ganglion,
sending branches to the renal plexus and suprarenal capsule.
The lesser splanchnic arises from the tenth and eleventh,
and, piercing the crus, ends in the celiac plexus, communicating
with the preceding and the renal plexus.
The least splanchnic arises from the last ganglion, and pierces
the crus, joining the renal plexus and sending branches to the
celiac plexus. :

THE SYMPATHETIC NERVES OF THE LUMBAR REGION

In the lumbar portion the ganglia lie in front of the spine,
along the inner side of the psoas. They communicate with
the ganglia above and below, and by two branches with each
of the spinal nerves.

Branches. Some cross the aorta to join the aortic plexus;
some cross the common iliacs and enter the hypogastric plexus;
others supply the vertebree and their ligaments.

THE SYMPATHETIC NERVES OF THE SACRAL REGION

In the sacral portion the ganglia lie internal to the anterior
sacral foramina, sending branches to the ganglia above and
below, and two branches each to the sacral nerves. The re-
maining branches join together and send filaments, some to
enter the pelvic plexus and others to form a plexus on the
middle sacral artery. The two lowest ganglia on each side
are joined by a loop over the coecyx, on which is the ganglion
umopar.

THE SYMPATHETIC PLEXUSES

The cardiac plexus lies at the base of the heart, and consists
of a superficial and a deep part.

378 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The superficial cardiac plexus lies between the aorta and the
right pulmonary artery. It is formed by the left superior
cardiac nerve and the lower cervical cardiac branch of the
left vagus, a small ganglion (Wrisberg’s) being found at their
point of union. It forms a great part of the right coronary
plexus, and sends filaments to the anterior pulmonary plexus,
and sends branches to the deep cardiac plexus.

The deep cardiac plexus lies in front of the trachea at its
bifurcation, above the point of division of the pulmonary artery
and behind the aorta. It receives all the cardiac branches of
the sympathetic, excepting the left superior cardiac; and of the
vagus and its recurrent branches, excepting the lower cervical
cardiac branch of the left side.

From the left side of the plexus branches pass to the super-
ficial cardiac plexus and to the left coronary plexus. From
the right, the branches in part join those from the superficial
plexus to form the right coronary plexus; some pass to the
left coronary plexus, others to the right auricle. Both sides
of the plexus furnish filaments to the anterior pulmonary
plexuses.

The left coronary plexus surrounds the left coronary artery
and its branches, and supplies the cardiac muscle. The right
surrounds the right coronary artery in a similar way. The
former receives its filaments from the deep plexus, the latter
from both superficial and deep.

The epigastric (solar) plexus is placed in front of the aorta
and crura of the diaphragm, behind the stomach, and between
the suprarenal bodies. It receives the great splanchnic nerves,
and the vagi send branches to it. It consists of a collection
of nerves and ganglia, and its branches accompany the vessels
to the principal viscera of the abdomen.

The largest of its ganglia are the semilunar, one on each
side. They lie near the suprarenal bodies, in front of the
crura, the right one beneath the inferior vena cava. They
receive the great splanchnic nerves. The lower portion of each
semilunar ganglion is detached, and is called the aorticorenal
ganglion.

The branches of the solar plexus form secondary plexuses,
and are the following:

The phrenic plexus, on the artery of the same name, to the
diaphragm, supplies also the suprarenal capsules. It joins

THE SYMPATHETIC PLEXUSES 379

with branches from the phrenic nerve, and at the point of
junction on the right side is a small ganglion, the diaphragmatic,
on the under side of the diaphragm.

The suprarenal plexus receives branches from the phrenic
plexus and great splanchnic nerves. At the point where the
latter join is a ganglion.

The renal plexus receives filaments from the aortic plexus
and the small and smallest splanchnics. The branches run
along the renal artery, and send filaments to the spermatic
plexus and to the inferior cava.

The spermatic plexus is derived from the renal and aortic
plexuses, and runs on the spermatic vessels. In the female
(ovarian) it supplies the uterus and ovaries.

The celiac plexus surrounds the celiac axis, and divides
into the gastric, hepatic, and splenic plexuses, which accompany
the corresponding vessels. It receives splanchnic branches;
on the left side it receives also filaments from the right vagus.

The gastric plexus receives filaments from the vagi.

The hepatic plexus receives branches from the left vagus,
and sends nerves to the right suprarenal plexus, and forms
secondary plexuses, which follow the branches of the hepatic
artery.

_ The splenic plexus is reinforced from the left semilunar
ganglion and the right vagus.

All the above plexuses run along with the arteries, and sub-
divide into secondary plexuses, corresponding to the arterial
branches, which form complex communications with one
another. The same applies to the following:

The superior mesenteric plexus is reinforced by a branch
from the union of the celiac axis and right vagus.

The aortic plexus, on the abdominal aorta, is reinforced by
filaments from the solar plexus and lumbar ganglia, renal
plexuses and semilunar ganglia. It ends in the hypogastric
plexus.

The inferior mesenteric plexus arises from the preceding,
and runs on the artery, joining superior mesenteric branches
and the pelvic plexus.

The hypogastric plexus is formed by lateral prolongations
from the aortic plexus and lumbar ganglia. It lies between
the two common iliac arteries. Below it bifurcates into the
two pelvic plexuses.

380 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The pelvic plexuses (inferior hypogastric) lie one on each side of
the rectum, and in the female, the vagina. They receive
filaments from the second, third, and fourth sacral nerves,
and where these join the plexus small ganglia are developed.
The nerves from the plexus supply all the pelvic viscera, accom-
panying the branches of the internal iliac artery and forming
the following secondary plexuses:

The hemorrhoidal plexus joins the superior hemorrhoidal
branches (from the inferior mesenteric plexus) to supply the
rectum.

The vesical plexus contains many spinal nerves, runs with
the vesical arteries, and sends nerves along the vas deferens.

The prostatic plexus consists of large nerves from the lower
part of the pelvic plexus, which supply the prostate, seminal
vesicles, and cavernous bodies. These latter are divided into
the small and large cavernous, and join the pudic branches.
The small pierce the fibrous coat near the root of the penis
and end in the erectile tissue. The large (single) runs forward
on the dorsum, and supplies the corpora spongiosa and corpora
cavernosa.

The vaginal plexus runs in the vaginal walls and mucous
membrane.

The uterine plexus sends some branches along the uterine
artery, and others which directly pierce the cervix and lower
part of the body. Branches pass also to the ovarian plexus and
fundus uteri.

THE ORGANS OF SPECIAL SENSE

THE EYE

The eyeball lies in the fat of the orbit, surrounded by a
tunic of fascia, the capsule of Tenon. It is composed of seg-
ments of two spheres, an anterior smaller and a_ posterior
larger, the junction of the sclerotic and cornea indicating their
limits. -It measures one inch transversely and vertically, and
somewhat less from before backward. Behind it receives
the optic nerve, and in front are the eyelids, eyebrows, etc.,
which comprise the so-called appendages of the eye.

Es BY oe et wn, gens diy

PE Ae 6 | «ek ag

eg ee! Gaels Ss Pe

THE EYE 381

The appendages of the eye include the eyebrows, eyelids,
conjunctiva, the lacrymal gland and sac, and the nasal duct.
The last three belong to the “lacrymal apparatus.”

The eyebrows (supercilia) are two prominent tracts of integu-
ment above the orbit, covered by thick hairs. They are
connected with the orbicularis, corrugator supercilii, and
occipitofrontalis muscles. :

The lids (palpebree) protect the eyeball. Each is composed
of thin integument, areolar tissue, muscular fibers, the tarsal
cartilage and ligament, Meibomian glands, and conjunctiva;
the upper lid, which is also the more movable, contains, in
addition, the aponeurosis of the levator palpebree.

The lids are separated, when opened, by a space, the fissura
palpebrarum, and are united at the angles (canthi). The
outer canthus is sharp, and the inner is more obtuse. At
the inner canthus, on each lid, is found the lacrymal tubercle,
pierced by the punctum lacrymale, the upper opening of the
lacrymal canal.

The tarsal cartilages (tarsi) are two plates of dense fibrous
tissue, one in each lid. Into the anterior surface of the upper
the levator palpebre is inserted. Each is attached at the
inner angle to the tendo oculi or internal tarsal ligament;
at the outer angle to the external tarsal ligament, which is
inserted into the malar bone.

The tendo oculi or palpebrarum is Y-shaped. The stem is
attached to the nasal process of the superior maxilla, and
each arm to one of the tarsal cartilages.

The palpebral ligament is a fibrous membrane attached to
the tarsal cartilages and to the corresponding margin of the
orbit.

The Meibomian glands (sebaceous) lie on the inner surface
of the lids, between the tarsal cartilages and the mucous mem-
brane. In the upper lid there are about thirty; in the lower,
fewer.

The lashes (cilia) are short, thick hairs forming a double
row on the free margin of each lid. Above they are longer and
more numerous.

The conjunctiva is the mucous membrane of the eye. The
palpebral portion is very thick and vascular, and forms at
the inner canthus a fold known as the plica semilunaris. The
ocular portion is loosely connected to the sclerotic, but over

382 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

the cornea consists only of the conjunctival epithelium. ‘The
line of reflection from the lid on to the eyeball is called the
fornix conjunctivee.

Near the inner canthus there is also a collection of follicles
constituting the caruncula lacrymalis, and external to this is
the plica semilunaris.

The lacrymal apparatus includes the gland, the two canals,
the sac, and the nasal duct. ~

The gland is about the size and shape of a small almond,
and lies in a depression in the orbital plate of the frontal bone
just inside the external angular process. Above it is attached
to the periosteum, and below it rests on the eyeball and the
upper and outer recti. In front it is closely connected to the

upper lid and is covered by conjunctiva. Its ducts, ten or -

more in number, run beneath the conjunctiva and open sepa-
rately at the outer part of the fornix.

The lacrymal canals commence by small orifices, the puncta,
on the margin of each lid, and empty close together into the
sac. The upper and longer ascends at first, then runs down-
ward and inward; the lower ones downward, then inward.

The lacrymal sac is the upper dilated part of the nasal ‘duct,
and lies in a depression formed by the lacrymal and superior
maxillary bones; it is invested by an aponeurosis derived from
the tendo oculi, and is crossed by the tensor tarsi.

The nasal duct is contained in a canal formed by the superior
maxilla, laerymal and inferior turbinated bones, and runs
from the lacrymal sac to the inferior meatus. It is lined with
a mucous membrane continuous with the conjunctiva, is
narrowest in the middle, and at its lower expanded orifice
is the valve of Hasner. Its direction is downward, backward,
and outward. Its epithelium 1 is ciliated.

The eyeball consists of three coats enclosing the refractive
media or humors. They are the sclerotic and cornea outside,
the retina internally, and the choroid between them.

The sclerotic coat is a dense fibrous membrane, white and
smooth externally, excepting where it receives the insertion
of the recti and obliqui. Internally it is brown, grooved by
the ciliary nerves, and united by a connective tissue, the
lamina fusca, to the choroid beneath. It covers the posterior
five-sixths of the eyeball. Behind it receives the optic nerve
at a point just internal to the centre, the fibrous sheath of

<u
Te ae Dene thet ae

THE EYE 389

the former being continuous with the sclerotic. Here there is
a number of small apertures (lamina cribrosa) for the funiculi
of the optic nerve, and outside of these smaller foramina for
the passage of vessels.

The cornea forms the anterior sixth of the external coat.
It is transparent and projecting, and nearly an arc of a true
sphere, the anterior surface being convex and the posterior

surface concave.

Fie. 66

DP
r . aS 2. Red,
Puncta lacrimalia.< | Be eo Y Sate f

ye

aC Yl

. The lacrymal apparatus. (Gray.)

The choroid or intermediate coat is continued into the choroid,
prolonged into the iris anteriorly, and forming the ciliary

processes.

It is a chocolate-colored vascular structure lying between
the sclerotic and retina and investing the posterior five-sixths
of the eyeball, blending in front with the iris after forming
a number of folds, the ciliary processes. Behind it is pierced
by the optic nerve. It is smooth internally, and is connected
to the lamina fusca of the sclerotic externally.

The ciliary processes, seventy or more in number, consist
of a circle of folds or thickenings of the choroid received into
pits in the vitreous and suspensory ligament of the lens. They

384. NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

are divided into a larger and a smaller set, the former being
about one-tenth inch in Jength. ‘Their inner surface is covered
by the layer of hexagonal pigmented cells of the retina.

The choroid is really a plexus of fine bloodvessels. Externally
it presents a membrane, the lamina suprachoroidea, between

Fia. 67

Canal of Schlemm.

; Anterior chamber.
Posterior

chamber. yy
Citiary oh

External {i Cavity occupied
rectus Wi \
. Internal
muscle, by vitreous humor. i rectus
muscle

Retina.

Choroid
coat.

Canal for
central artery.
Sclerotic coat. | i AN
Nerve sheath. A \\ Optic nerve.

A horizontal section of the eyeball. (Allen.)

which and the lamina fusca is a lymph-space which commu-
nicates with the capsule of Tenon through apertures in the
sclerotic.

The ciliary muscle is a circular plane of unstriped muscle
placed between the choroid and sclerotic at its anterior part.

we

) THE EYE — 885

It consists of circular and radiating fibers. The latter arise
near the union of the sclerotic and cornea, and are inserted
into the choroid opposite the ciliary processes; the former
surround the insertion of the iris.

The iris gives to the eye its color. It is a thin, contractile,
circular membrane presenting, at about its centre, a circular
aperture, the pupil. It is suspended in the aqueous humor
behind the cornea and in front of the lens. Its circumference
is continuous with the choroid, and, through the lagamentum
pectinatum, with the cornea. Its posterior surface is covered
by dark pigment resembling that of a ripe grape; hence the
term “uvea.’’ ‘The edges of the pupillary orifice are in con-
tact with the lens, the size of the pupil varying from 35 to 3
inch across.

The muscle fibers are radiating and circular. The latter
form a sphincter for the pupil; the former constitute the dilator
muscle.

The arteries are supplied from the long and anterior ciliary.
The nerves are branches of the lenticular ganglion and the
long ciliary from the nasal branch of the ophthalmic. They
form a plexus around the circumference of the iris, and end
in the muscular fibers and in a network on the front of the:
iris. The nerves to the circular fibers come from the motor
oculi; those to the radiating, from the sympathetic.

The retina is a delicate nervous membrane on which the
image of perceived objects is formed. It lies between the
choroid and the hyaloid membrane of the vitreous, and is
composed of ten layers. Behind, the optic nerve expands into
it, and in front it terminates in a dentated margin, the ora
serrata, at the outer edge of the ciliary processes. It then
sends off a thin, non-nervous membrane, the pars ciliaris
retine, to the tips of the ciliary processes. The inner surface
of the retina presents at its centre an elliptical spot about
zy inch across, the macula lutea. In the centre of this spot
is a depression, the fovea centralis, which, on account of the
extreme thinness of the retina, shows the pigmentary layer of
the choroid, and hence presents the appearance of a foramen.
About ;'5 inch to the inner side of the yellow spot is the porus
opticus, at which point the’ optic nerve enters, the nervous -
matter being heaped up here so as to form the colliculus. Pass-
ing through nearly the entire thickness of the retina, supporting

25

386 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

its layers and binding them together, are the radiating fibers,
or fibers of Miiller. They form at one extremity the membrana
limitans interna, and at the other the externa.

The vitreous body is a transparent gelatinous fluid enclosed
in a transparent membrane, the hyaloid, and fills about four-
fifths of the eyeball. In front it is hollowed out to receive the
lens and its capsule, being adherent. to the back of the latter.
In the centre of the vitreous from the entrance of the optic
nerve to the back of the lens runs a canal. It contains fluid,
is about ;/; inch in diameter, and is called the canal of Stilling.

The crystalline lens is a solid transparent biconvex body
which lies, enclosed in its capsule, in front of the vitreous
and behind the iris. The greater convexity is behind, and the
lens measures anteroposteriorly + inch and transversely 4 3 inch.
It consists of concentric laminze which ¢ are progressively harder
from without inward.

The capsule is an elastic, transparent, structureless mem-
brane, in contact anteriorly with the iris and held in place by
the suspensory ligament.

The suspensory ligament is a thin, transparent membrane
placed between the vitreous humor and the ciliary processes,
and presents externally a number of folds which receive those
of the ciliary processes. It is really a part of the hyaloid mem-
brane, which runs forward to the front of the margin of the
lens. It is also called the zonula of Zinn, and is covered exter-
nally by the pars ciliaris retine. Between its back part and
the lens is a space, the canal of Petit. This canal is bounded
in front by the suspensory ligament (zonula of Zinn), behind
by the vitreous, and at its base is the capsule of the lens.

The aqueous humor is the fluid which fills the space between
the suspensory ligament and capsule behind and the cornea
in front. That part of this space which lies in front of the
iris is called the anterior chamber; the part behind the iris is
the posterior chamber. The latter is really only the small
interval between the iris, suspensory ligament, and ciliary
processes.

For a more complete description of the minute structure
of the eye the reader is referred to the standard books on
anatomy and histology.

THE EAR 387

THE EAR

The ear is divided into the external ear, the middle ear, or
tympanum, and the internal ear, or labyrinth.

The external ear, the projecting part, or pinna, and the
external auditory canal and meatus. The pinna or auricle is
ovoid in outline, concave externally, and facing outward and
somewhat forward, presenting eminences and depressions
to which various names have been given. ‘Thus, the most
external ridge is the helix; parallel and internal to this is the
antiheliz, a ridge which divides above to enclose the fossa of
the antihelix; between these two ridges is the fossa of the helix
(fossa scaphoidea); in front of the antihelix is a deep depres-
sion, the concha, which presents above and in front the com-
mencement of the helix; in front of the concha is a small process,
the tragus, which points backward; and behind this is the
antitragus, a deep notch, the incisura intertragica, separating
the two; and lastly, below these is the lobule.

The pinna consists of a plate of yellow fibrocartilage covered
by skin and some adipose tissue. It enters also into the forma-
tion of the external meatus, being attached to the external
auditory meatus of the temporal bone. The lobule contains
only fat and strong fibrous tissue.

The external auditory canal is 1% inches long, and runs from
the concha to the membrana tympani. It is directed obliquely
forward, inward, and downward, and presents an eminence
in the floor of the osseous part, which makes the direction of
the canal at first upward, then downward. It is narrowest
at its middle. Its floor is longer than the roof, on account of
the oblique position of the membrana tympani. It opens
externally by means of the external auditory meatus.

The middle ear, or tympanum, is a cavity in the petrous portion
of the temporal bone, extending from the membrana tympani
to the outer wall of the labyrinth. Its width varies from 3’;
to 4 inch. It contains the ossicles of the ear, with their liga-
ments and muscles, and certain nerves. It is filled with air,
and communicates by means of the Eustachian tube with the
pharynx.

The roof of the tympanum is formed of very thin bone, which
separates it from the cranial cavity. The floor is also of bone

388 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

and separates it from the jugular fossa beneath and the carotid
canal in front. The outer wall is formed by the membrana
tympani and the ring of bone into which this is inserted, and
presents, just in front of the bony ring, the Glaserian fissure,
which lodges the processus gracilis of the malleus and trans-
mits some tympanic vessels; at the back part, the iter posterius
for the entrance of the chorda tympani, and the iter anterius,
anteriorly, for its exit. The former leads to the aqueeductus
Fallopii, the latter to the canal of Huguier. .

Fria. 68

Cartilage of
the pinna

Promont.

Int. carot, a.
Membrana
tympani “1
Cartilage of the ext. A
auditory meatus |

Transverse section of external auditory meatus and tympanum. (Gegenbaur.)

The membrana tympani is a thin membrane inserted into
a ring of bone at the bottom of the external canal, which is
grooved for its reception. It is:ovoid in form and directed
obliquely downward and inward. On its inner surface is the
handle of the malleus, which extends from about the middle
of its roof to a little below its centre, covered by mucous mem-
brane where it is attached. This process draws the membrane
inward, making its outer surface concave and its inner convex.
Externally, the membrane is covered by skin, continuous
with that of the meatus; internally, with mucous membrane,
continuous with that of the tympanum; and between these
two is a fibrous layer, some of its fibers radiating from the

THE EAR 389 .

handle of the malleus, others being circular and placed near
the circumference. At the anterosuperior part of the membrane
is a notch in the bony ring, the notch of Rivini. That part
of the membrane occupying it is called the membrana flaccida.

The inner wall of the tympanum is vertical and uneven.
It presents the following: (a) The fenestra ovalis, leading
into the vestibule, and occupied in the recent state by the
base of the stapes and its annular ligament. (b) Fenestra
rotunda, in a conical fossa leading into the cochlea, a rounded
eminence. (c) The promontory, separating it from the preceding.
It is closed, in the recent state, by the membrana tympani

View of inner wall of tympanum. (Gray.)

secundaria. This is composed of three layers, and is concave
_toward the tympanum. The middle layer is fibrous, the outer
and inner being continuous with the lining membrane of the
two cavities. The promontory indicates the first turn of the
cochlea, and is grooved for branches of the tympanic plexus. .
(d) The ridge of the aqueductus Fallopii, running above the
fenestra ovalis and descending on the posterior wall. (e)
The pyramid, a hollow eminence containing the stapedius,
the tendon of the muscle escaping through a foramen in its
summit. A minute canal containing the nerve to this muscle
runs from the aquzeductus Fallopii to the cavity of the pyramid.

390 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The posterior wall of the tympanum presents above one
large and several small apertures leading to the mastoid cells.

The anterior extremity opens into two canals separated by
a process of bone, the processus cochleariformis. The upper of
these canals is the smaller and transmits the tensor tympani;
the lower contains the Eustachian tube, and osteocartilaginous
passage 13 inches long, leading to the pharynx. Both of these
canals run in a direction downward, forward, and inward.

The osseous part of the Eustachian tube is } inch long, and
to its lower end is attached the triangular piece of fibrocartilage
forming the remainder of the tube. The edges of the cartilage
are not in contact, but are joined by fibrous tissue. The tube
is wide at its lower extremity, and opens at the upper and
lateral part of the pharynx, above the hard palate and behind
the lower turbinated bone. It is lined by epithelium continuous
with that of the pharynx.

The ossicula are three small movable bones, named the
malleus, incus, and stapes. The first is attached to the mem-
brana tympani; the second is between the other two; the
last named is attached to the fenestra ovalis.

The malleus (a hammer) consists of a head, neck, and three
processes, viz., the processus gracilis, the processus brevis,
and the manubrium. The head articulates with the incus.
The neck is below it, and rests on a prominence which is con-
nected with the three processes. The manubrium tapers to
its extremity, which is flattened, and it is connected with
the membrana tympani. The tensor tympani is attached to
its inner side near its upper end, and from its root springs
the processus bres. The processus gracilis is long and slender,
and is connected by bone and fibrous tissue with the Glaserian
fissure. .

The incus (an anvil) has a body and two processes. The
body presents a saddle-shaped articular surface for the malleus;
the short process is conical, looks backward, and is attached to
the opening which leads to the mastoid cells; the long process
descends behind the manubrium of the malleus, to end in
the os orbiculare, or lenticular process, which articulates with
the head of the stapes.

The stapes (a stirrup) presents a head, which articulates
with the os orbiculare; a neck, to which is attached the stapedius
muscle; and two crura, diverging from the neck, and connected

THE EAR 391

at their extremities by the base, which fills up the fenestra
ovalis.

The articulations between the several bones are provided
with synovial membranes; their surfaces are covered with
cartilage and are connected by capsular ligaments. The
following ligaments connect the bones with the walls of the
tympanum:

The anterior ligament of the malleus is attached to the neck
of the malleus at one end, and at the other to the anterior wall
of the tympanum close to the Glaserian fissure, and its sus-
pensory ligament runs from the roof of the tympanum to the
head of the bone. An external ligament runs from the notch
of Rivini to the body and lesser process, and the accessory
anterior ligament is the thickened front portion of the sheath
of the tensor tympani, which runs from the anterior wall to
the manubrium and neck. An inferior ligament runs from the
end of the handle to the outer wall of the tympanum.

The base of the stapes is fixed to the margin of the fenestra
ovalis by an annular ligament.

The ineus is provided with a posterior ligament, running
from the short process to the posterior wall, and a suspensory
ligament, from the roof of the tympanum to the upper part
of the bone near its articulation with the malleus.

The Muscles of the Middle Ear.—The tensor tympani runs in
the canal previously mentioned. Arising from the under surface
of the petrous portion, the cartilage of the Eustachian tube,
and the margins of its own canal, its tendon is reflected over
the processus cochleariformis and is inserted into the handle
of the malleus near its root. It pulls on the malleus, thus
drawing inward and making tense the membrana tympani.
Its nerve comes from the otic ganglion.

The stapedius arises from the sides of its containing cavity
within the pyramid, and, emerging from the apex, is inserted
into the neck of the stapes. It draws the head of the stapes
backward, thus pressing the base against the fenestra ovalis
and compressing the contents of the vestibule. Its nerve is
the tympanic branch of the facial.

The mucous membrane of the tympanum is pale and thin
and its epithelium ciliated. It invests the contents of the
cavity, the inner surface of the membrana, and covers the
fenestra rotunda. It is continuous with that of the mastoid
cells, Eustachian tube, and pharynx.

392 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

The tympanic arteries come from the internal maxillary,
the stylomastoid branch of the posterior auricular, the petrosal
branch of the middle meningeal, the Eustachian branch of
the ascending pharyngeal, and from the internal carotid. The
veins reach the internal jugular by means of the middle menin-
geal and pharyngeal veins.

The nerves of the tympanum are the muscular, already men-
tioned; the nerves to the mucous membrane from the tympanic
plexus; the communicating, viz., between Jacobson’s nerve,
the sympathetic, and branches of the geniculate ganglion of
the seventh; and the chorda tympani.

Jacobson’s nerve (tympanic branch of the ninth) enters
the tympanum in the floor and passes to the promontory.
It forms the tympanic plexus, from which are supplied the
fenestre, Eustachian tube, and lining membrane, and sends
off two communicating branches—one to the carotid plexus,
one to the great superficial petrosal. It then receives a fila-
ment from the geniculate ganglion of the facial, and proceeds
to join the otic ganglion as the lesser superficial petrosal nerve.

The chorda tympani arises from the facial near the stylo-
mastoid foramen, enters at the base of the pyramid, crosses
the tympanum between the long process of incus and handle
of malleus, and runs through the iter chorde anterius to the
canal of Huguier.

The internal ear is the essential part of the hearing apparatus,
since here the auditory nerve is distributed. It is contained
in a cavity in the petrous bone, and is made up of the osseous
labyrinth and of the membranous labyrinths.

The osseous labyrinth contains the membranous labyrinth,
and is divided into three parts: the vestibule, semicircular
canals, and cochlea. It communicates in the dry state with
the tympanum by means of the fenestrae. Between the osseous
and membranous labyrinth is a space occupied by a clear
fluid, the perilymph, and within the membranous labyrinth
is the endolymph. .

The vestibule is the central cavity lying between the cochlea
in front and the semicircular canal behind, the tympanum
being external. Its outer or tympanic wall presents the fenestra
ovals.

Its inner wall has in front a depression, the fovea hemispheriea,
pierced by several minute holes for the auditory filaments,

THE EAR 393

and, behind this, a ridge, the crista vestibuli. Behind this
ridge is the opening of the aqgueductus vestibuli. In the roof
is a depression, the fovea hemielliptica. .

Behind, the vestibule presents five foramina leading into
the semicircular canals, and in front a larger foramen leading
into the seala vestibuli of the cochlea.

The semicircular canals are three bony tubes of unequal
length lying above and behind the vestibule, each forming
about two-thirds of a circle. Their general diameter is 5
inch, but at one end is a dilatation, the ampulla, ;5 inch in
diameter. They empty into the vestibule by five apertures,
in one of which two tubes join.

The superior is vertical and is set transversely, forming
an eminence seen on the upper surface of the petrous bone.
The ampulla of this tube opens into the upper part of the
vestibule, the other end opening by a foramen into the back
part, in common with the posterior canal.

The posterior is also vertical, but is set anteroposteriorly
and is longer than the others, its ampulla being at the postero-
inferior part of the vestibule, the other extremity joining with
the preceding canal, as described.

The eaternal is horizontal and the shortest, its ampulla
being at the outer part, above the fenestra ovalis, and the
other end at the upper and back part of the vestibule.

The cochlea resembles a snail shell. Its apex looks forward
and outward, and its base toward the internal auditory meatus.
Within is a centre piece, the modiolus, or columella, around
which the canal runs spirally for two and a half turns.

Within the canal, and attached to the modiolus, is the
lamina spiralis. ‘This plate of bone partially divides the spiral
canal into two compartments, or scale, the division being
completed by a membrane (see below) which reaches the
outer wall of the cochlea. The upper scala is known as the
scala vestibuli; the lower is the scala tympani.

The modiolus, or columella, the centre piece of the cochlea,
runs from base to apex. It is conical in form, the base corre-
sponding to that of the cochlea, and is pierced by foramina
for the cochlea branches of the auditory nerve and for the
vessels which pass to the lamina and spiral canal. One of
these, larger than the rest, is the opening of the canalis modtolt
centralis. Diminishing gradually in size, the modiolus termi-

394. NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

nates above in a bony process, the infundibulum, which blends
with the cupola or last half turn of the spiral canal. Here
the two scale communicate by a small opening, the helicotrema.
Around the modiolus, along the attachment of the lamina
spiralis, is the spiral canal of the modiolus, containing a gan-
gliated portion of the cochlear nerve, the ganglion spirale.

The spiral canal is 14 inches long and ;5 inch in diameter
at its widest part, eyes is below. The scala vestibuli com-
municates with the vestibule by the foramen above mentioned,
and a part of it, marked off by a membrane, is called the scala
media (see below). The scala tympani commences at the
fenestra rotunda, and close to its commencement is the opening
of the aqueductus cochlee, by which it communicates with the
subarachnoid space, and in which there is transmitted a small

vein to the internal jugular. The spiral lamina ends above,

in a hook-like process, the hamulus, which partly bounds the
helicotrema.

The membranous labyrinth is contained within the osseous
labyrinth, having a similar form, though smaller and separated
from it by the perilymph. It contains the endolymph and
receives the distribution of the auditory nerve. In the vestibule
it consists of the utricle and the saccule.

The utricle is in the upper and back part, its cavity com-
municating by five apertures with the membranous semicircular
canals. It is in contact with the fovea hemielliptica.

The saccule is in the fovea hemispherica, and communicates
with the utricle by means of a small tube which passes into
the aqueductus vestibuli, and there joins a canal (saccus endo-
lymphaticus), which canal is prolonged from the utricle and
ends in a blind extremity; and with the scala media by means of
the canalis reuniens.

The membranous semicircular canals are similar in shape
to but are only from one-fifth to one-third the diameter of
the bony canals; the ampulle, however, are relatively large.
Two small masses of calcium carbonate are found in the utricle
and saccule. They are called the otoliths.

In the cochlea the membranous labyrinth is represented
by the scala media and the parts therein, which are formed
as follows:

Along the edge of the spiral lamina the periosteum on its
upper surface is raised up like a C to form the limbus lamine

»
ee ee oe

THE EAR 395

spiralis. Thus there is a groove (the sulcus spiralis), the upper
and lower lips of this sulcus being called respectively the labium
vestibulare and tympanicum. From the latter the membrana
basilaris extends to the outer wall, along the latter attach-
ment forming the ligamentum spirale. Above the limbus
to the outer wall stretches another membrane, Reissner’s.
The space below the osseous lamina and the membrana basilaris
“is the scala tympani; above the membrane of Reissner is the
scala vestibuli; and that space bounded by the two membranes
and the outer wall of the cochlea is known as the scala media,
or canal of the cochlea, which ends at the apex of the cochlea
- in a blind pointed extremity, and opens below into the saccule,
as described above. Between the two membranes mentioned
a third stretches across in the scala media to the outer wall.
This is called the membrane of Corti, or membrana tectoria.
Between the membrana basilaris and the last-named mem-
brane is a space which contains the organ of Corti.

The organ of Corti lies on the basilar membrane. The central
part is composed of two rows of peculiarly shaped cells called
the rods of Corti, outer and inner. These rods meet above
by their extremities, and enclose an angular tunnel between
them and the basilar membrane, the zona arcuata. The inner
rods run close to the labium tympanicum, and along their
inner side is a series of epithelioid cells continuous with the
cubical epithelium of the sulcus spiralis. These present a
row of short, stiff hairs, forming a sort of brush. External
to the outer rods are several rows of similar cells. These are
called the outer and inner hair cells.

The reticular lamina is a delicate structure composed of
small segments called phalanges arranged side by side and
separated by holes, through which the hairs of the outer hair
cells project. The whole organ thus described is covered by
the membrane of Corti (membrana tectoria).

The arteries of the internal ear are the auditory branch of
the basilar, the stylomastoid branch of the posterior auricular,
and branches occasionally from the occipital. The first named
divides into a cochlear and a vestibular branch.

The auditory nerve divides at the bottom of the internal
auditory meatus into a swpervor and an inferior branch. The
former divides into branches, which are distributed to the
utricle and to the ampulle of the superior and external semi-

396 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM

circular canals; the latter sends branches to the saccule, to
the ampulla of the posterior canal, and to the cochlea.

The cochlear branch sends its filaments through the canals
of the modiolus, and these form the ganglion spirale. This
ganglion sends other filaments to the sulcus spirale and organ
of Corti.

THE NOSE

The nose is the organ of smell, and consists of an eaternal
part, the nose, and an internal, the nasal fosse.

The nose is pyramidal, and is formed by the nasal bones
and nasal processes of the superior maxillary bones, and of
five cartilages, viz., the two upper and the two lower lateral
cartilages, and the cartilage of the septum. The two open-
ings, the anterior nares, are directed downward, and just
inside of them are some short, stiff hairs, the vibrissz. The
bones and cartilages are covered by skin on the outer side
and by mucous membrane on the inner. Between the anterior
nares is a fold of skin, the columna nasi, which continues the
septum. ‘The two lateral parts join in front to form the dorsum
and this ends below in the rounded lobe of the nose.

The upper lateral cartilages lie one on each side, below the
nasal bones, and are triangular in form. The anterior margin
joins its fellow above and the edge of the cartilage of the sep-
tum below. The inferior edge joins the lower lateral cartilage
by means of fibrous tissue, and the posterior edge the nasal
and superior maxillary bones.

The lower lateral cartilages are thin, and are curved so as
to form the front and both walls of the nostrils. Behind it is
attached to the superior maxilla, above to the upper cartilage.

Between it and the former several smaller cartilages may be

seen. It also joins a small part of the cartilage of the septum.
In front it joins its fellow to form the tip of the nose.

The cartilage of the septum is quadrilateral, and thinner at
the centre than at its borders. It forms the anterior part of
the septum, and is joined superiorly to the nasal bones, and
to the upper and lower lateral cartilages by its anterior margin.
Its posterior margin is attached to the front of the perpendicular
plate of the ethmoid, and its lower margin to a groove on the
vomer and the ridge between the superior maxillee.

THE NOSE | 397

The nasal fosse (for the osseous part, see Bones) open in
front by the anterior nares, and into the pharynx behind by
the posterior nares. The mucous membrane is called the
pituitary, or Schneiderian membrane, and is attached directly
to the periosteum or perichondrium. It is continuous with
that of the pharynx, conjunctiva, tympanum, and mastoid
cells, antrum of Highmore, and with that of the different
canals which connect these parts.

The epithelium is squamous near the nostril, columnar
where the olfactory nerves are distributed, and columnar and
ciliated elsewhere.

The nasal fossze in the recent state present a different appear-
ance from that seen in the skeleton. They are narrowed, and
their component parts appear thicker, their turbinated bones
being very prominent. The apertures of the various foramina
are narrowed; or even closed, by the lining membrane.

The arteries of the nasal fosse are the anterior and posterior
ethmoidal from the ophthalmic, supplying the ethmoidal cells and
frontal sinuses and roof of the nose; the sphenopalatine from the
internal maxillary, to the mucous membrane covering the spongy
bones, meatuses, and septum; the inferior artery of the septum,
from the superior coronary of the facial, and the infraorbital and
alveolar branches of the internal maxillary, which supply the
lining membrane of the antrum.

The veins empty into the ophthalmic and facial, and through
the foramen cecum communicate with the cranial sinuses.

The nerves are the olfactory filaments distributed to the
upper third of the septum and the surfaces of the superior
and middle turbinated bone (these filaments do not reach
the middle or inferior meatus), the nasal branch of the oph-
thalmic, the anterior dental of the superior maxillary, the
Vidian, nasopalatine, anterior palatine and nasal branches of
the sphenopalatine ganglion.

The lymphatics from the external surface drain into the sub-
maxillary and those from the fosse into the retropharyngeal
nodes.

Fef aux

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MAT
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ae ‘, Sao “ey

QUESTIONS ON NEUROLOGY

THE CEREBROSPINAL AXIS

What are the enlargements of the cord? To what are these enlarge-
ments due?

eceme speaking, what form does the gray matter of the cord
take? — .

Name the fissures and columns of the cord.

What are the membranes of the cord and brain?

What is the lowest part of the cord called and how low does it extend?

What are the peduncles of the cerebellum?

Name the main lobes of the cerebellum.

Name in order the lobules and interlobular fissures of the upper
surface of the cerebellar worm and hemispheres.

Describe the fourth ventricle, giving its location, boundaries, roof,
and the markings of its floor.

What are the nuclei of the optic thalami?

Describe the fissures on the convex surface of each hemisphere,
giving the names of the lobes thus divided off.

Describe the fissures and lobes of the median surface.

What is the corpus callosum?

Where is the island of Reil?

Describe the lateral ventricles.

Describe the hippocampus major.

THE PERIPHERAL NERVE SYSTEM

Give in order the names of the twelve cranial nerves.

Tell how each of the cranial nerves makes its exit from the skull.

Describe the optic chiasm.

What muscles does the third nerve supply?

What are the three branches of the ophthalmic division of the fifth
cranial nerve?

Why is the sixth cranial called abducens?

weer does the facial nerve enter the skull? Where does it come
out

What are the main divisions of the facial nerve?

Describe precisely the course and branches of the pneumogastrics.

How do the right and left recurrent laryngeal nerves differ in origin?

Where do you look in the neck for the recurrent laryngeals?

What muscle does the spinal accessory often pass through?

What muscles does the spinal accessory supply in part?

Describe the course and relations of the hypoglossal.

What muscles does the hypoglossal supply?

Where and how is the phrenic nerve formed?

Is the phrenic in front of or behind the root of the lung?

Draw the plan of the brachial plexus.

How and where is the median nerve formed?

Give the course and relations of the median nerve.

How may the median nerve be located opposite the wrist?

Name the digital branches of the median nerve.

What muscles of the hand does the median nerve supply?

What nerve supplies all the other muscles of the hand?

From what cord does the musculospiral nerve come?

How and where does the musculospiral nerve end below?

What does the radial nerve supply?

How does the posterior interosseous nerve get to a posterior position?

What are the muscular relations of the ulnar nerve in the forearm,
and what muscles does it supply there?

Between what muscles is the anterior crural nerve just below
Poupart’s ligament?

whe separates the anterior crural nerve from the common femoral
artery!

What structures pass between the anterior and posterior groups
of the branches of the anterior crural nerve?

What relation does the external cutaneous nerve bear to the sar-
torius muscle just after leaving the abdominal cavity? .

What structure separates the branches of the obturator nerve?

Where does the obturator nerve leave the pelvis?

To which side of the great sciatic nerve is the small sciatic?

Upon what muscles does the great sciatic nerve lie?

Into what does the great sciatic divide?

Between what muscles does the peroneal nerve lie, opposite the
knee-joint?

Where is the peroneal nerve subcutaneous, and where does it divide?

What various relations does the anterior tibial nerve bear to the
anterior tibial artery?

Where does the anterior tibial nerve terminate?

At what point does the popliteal nerve become the posterior tibial?

What are the articular branches of the popliteal and peroneal nerves,
and what vessels do they accompany?

Of what nerve are the internal and external plantar nerves branches,
and to what nerves of the hand do they very closely correspond?

THE SYMPATHETIC NERVE SYSTEM

Is the sympathetic system directly connected with the cerebro-
spinal system? ; ;
What are the principal trunks of the sympathetic system?

THE ORGANS OF SPECIAL SENSE

Describe the eyeball

What and where are the Meibomian glands?
Describe the lachrymal apparatus .

What do the chambers of the eye contain?

Just where is the lens, and what holds it in place?
Locate and describe the tympanum!

Describe the Eustachian tube.

Describe the nasal fossze.

PART VI

SPLANCHNOLOGY, OR THE ANATOMY OF
THE VISCERA

THE ORGANS OF RESPIRATION

THE LARYNX

THE larynx is the organ of the voice, and is placed at the
upper and forepart of the neck, between the trachea and base
of the tongue.

Relations.—It has on each side of it the great vessels, and
behind it the pharynx. In front are the pretracheal portion
of the cervical fascia and the upper end of the thyroid gland,
and on each side the sternohyoid and thyroid and the thyro-
hyoid muscles. It consists of various cartilages held together
by ligaments, and is lined internally by mucous membrane.

The cartilages are nine: Three pairs, the arytenoid, cornicula
laryngis, and cuneiform; and three single, the thyroid, cricoid,
and epiglottis.

The thyroid cartilage is the largest, and consists of two lateral
parts or ale uniting in front to form the projection of the
pomum Adami. ‘This is subcutaneous, more distinct above
and in the male. Each ala is quadrilateral, and presents
externally a tubercle from which a ridge descends obliquely
forward. This ridge gives attachment to the sternothyroid
and thyrohyoid, and the surface behind it to the inferior con-
strictor muscle. Internally it is smooth, and in the angle the
epiglottis, true and false vocal cords, and the thyroarytenoid
and thyroepiglottidean muscles are attached. The upper
border is concavoconvex, and in front is notched over the

400 SPLANCHNOLOGY, OR. ANATOMY OF THE VISCERA

pomum Adami, giving attachment throughout to the thyro-
hyoid membrane. ‘The lower border is joined to the cricoid
cartilage by the middle portion of the cricothyroid membrane;
and on either side, affords attachment to the cricothyroid
muscle. The posterior borders end in the wpper and lower
cornua; to the upper are attached the lateral thyrohyoid liga-
ments, and the lower, which are shorter and thicker, present
internally a facet for articulation with the side of the cricoid car-
tilage. The stylopharyngeus and palatopharyngeus is attached
also to the posterior border.

The cricoid cartilage resembles a signet ring, is narrow in
front, and gives attachment to the cricothyroid muscle, and
behind it to some of the fibers of the inferior constrictor. It
is broad behind, with a vertical ridge for the attachment of
the longitudinal fibers of the esophagus, separating two hollows
for the cricoarytenoideus posticus, and presents at about the
middle of the lateral surface a prominence on each side which
articulates with the corresponding inferior cornu of the thyroid
cartilage. The lower border is joined to the upper ring of the
trachea; the upper border gives attachment in front and laterally
to the cricothyroid membrane and the lateral cricoarytenoideus
muscle. Behind, at each end of its upper border, is an oval
surface for the corresponding arytenoid cartilage, with a notch
between. The inner surface is smooth and lined with mucous
membrane.

The arytenoid cartilages are pyramidal in form, presenting
three surfaces, an apex and base, and rest by their bases on
the highest part of the upper border of the cricoid cartilage
behind, their curved apices approximating. ‘To the posterior
surface is attached the transverse portion of the arytenoid
muscle. The anterolateral surface is somewhat convex and
rough. From the colliculus, near the apex, starts a ridge
(crista arcuata) which passes backward then forward and
downward into a sharp pointed process, the vocal process.
The latter separates a deep depression above, the fovea tri-
angularis, from a broader and_ shallower depression below,
the fovea oblongata. To a small tubercle just above the base,
on the anterior border, is attached the origin of ligament of
the false vocal cord, the superior thyroarytenoid ligament.
To the outer part of the ridge, as well as the surface above
and below, is attached the thyroarytenoid muscle.

THE LARYNX 401 |

The cornicula laryngis (cartilages of Santorini) are two
small, cervical nodules, of yellow elastic tissue, which articulate
with the summits of the arytenoid cartilages and serve to
prolong them backward and inward. ‘They are lodged in the
arytenoepiglottic fold.

The cuneiform cartilages (Wrisberg’s) are two small, yellow
bodies of elastic cartilage, which stretch between the arytenoid
cartilage and the epiglottis. They are situated in the aryteno-
epiglottic fold.

The epiglottis is a fibrocartilaginous lamella, shaped like a
leaf, lying behind the tongue and in front of the upper orifice
of the larynx. Above it is broad, below narrow and prolonged
to the notch above the pomum Adami by the thyroepiglottic
ligament, or rather, to the angular interval just below the
notch, and is attached to the upper border of the body of the
hyoid bone by the hyoepiglottic ligament. Laterally are
attached the arytenoepiglottic folds of mucous membrane
extending back to the apices of the corresponding arytenoids.
They contain areolar tissue and a few muscular fibers. The
anterior surface is connected with the tongue by the lateral
and median glossoepiglottic folds. The posterior surface is
concave transversely, convex longitudinally.

_ The ligaments of the larynx are extrinsic and intrinsic. The
former connect it to the hyoid bone; the latter connect its
parts together.

The extrinsic ligaments are the middle thyrohyoid ligament,
the two lateral thyrohyoid ligaments, and the hyoepiglottic
ligament.

The middle thyrohyoid ligament is a fbiealaciie structure
attached to the entire border of the notch of the thyroid cartilage
and to the upper border of the posterior surface of the body
of the hyoid bone. The lateral thyrohyoid ligaments run between
the upper cornua of the thyroid and the greater cornua of the
hyoid bone. ‘They sometimes enclose the cartilago triticea,
a small cartilaginous nodule occasionally ossified. The hyo-
epiglottic ligament runs from the front of the epiglottis near
its apex to the upper border of the body of the hyoid bone.
The middle and lateral thyrohyoid ligaments are thickened
portions of the thyrohyoid membrane, due to the contained
elastic fibers. The cricotracheal ligament connects the cricoid
cartilage to the first ring of the trachea. It resembles the

26

402 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

fibrous membrane which connects the cartilaginous rings of
the trachea.

The intrinsic ligaments connecting the thyroid and cricoid
cartilages are the cricothyroid membrane, two capsular liga-
ments. The cricothyroid ligament is of yellow elastic tissue,
triangular, and consists of a central thicker portion connecting
the adjacent borders of the two cartilages, and two lateral
portions running from the upper border of the cricoid to be
continuous with the inferior thyroarytenoid ligaments (true
vocal cords). They extend from the vocal processes of the
arytenoid cartilages to the receding angle of the thyroid cartilage
near its centre. The lateral portions of the membrane are
lined internally by mucous membrane, and are separated from
the thyroid cartilage by the cricoarytenoideus lateralis and
thyroarytenoideus muscles. In the subcutaneous interval
there is a sort of plexus from the junction of the two crico-
thyroid arteries. The lower cornua of the thyroid are connected
with the sides of the cricoid by two ligamentous capsules
each lined by a synovial membrane.

The cricoid and arytenoid cartilages are connected by loose
capsular ligaments lined by synovial membranes, and by a
posterior cricoarytenoid ligament running ‘from the cricoid
to the inner and back part of the base of the arytenoid. The
movements between the inferior cornu of the thyroid and the
cricoid cartilage on either side is a diarthrodial one, and per-
mits of rotary and gliding movements. The movements
between the arytenoid cartilages and the cricoid is also a
diarthrodial one—gliding and rotary.

The interior of the larynx (cavum laryngis) is divided into
an upper and a lower part by the rima glottidis. The upper
opens into the pharynx by the wpper aperture of the larynx,
between which and the rima glottidis are the ventricles and
their saccules and the false vocal cords. The lower aperture
is continuous with the trachea.

The swperior aperture is cordiform in shape, widest in front
and narrow behind. In front it is bounded by the epiglottis,
behind by the arytenoid cartilages (together with the fold of
mucous membrane between them) and cornicula, and laterally
by the arytenoepiglottic folds.

The rima glottidis is the space between the true vocal cords
and the bases of the arytenoid cartilages. It is somewhat

THE LARYNX 403

less than 1 inch long, and according to its degree of dilatation,
from 3 to 3 inch wide. In easy respiration its form is triangular,
with the base posterior, and when fully dilated it is lozenge-
shaped.

The superior or false vocal cords are two mucous folds, each
enclosing the corresponding superior thyroarytenoid ligament.
This latter is a thin band running between the angle of the
thyroid and the anteroexternal surface of the arytenoid cartilage.

The inferior or true vocal cords are two strong bands, the
inferior thyroarytenoid ligaments, covered by mucous mem-
brane and attached to the depression between the ale of the
thyroid cartilage in front and the anterior angle of the base
(vocal process) of the arytenoid cartilages behind. Below,
each is continuous with the lateral part of the cricothyroid
ligament or membrane. Part of the thyroarytenoidei is external
and parallel to them. .

The ventricles of the larynx lie one on each side, between the
upper and lower vocal cords, bounded externally by the thyro-
arytenoidei. At the front a narrow opening leads into a blind
pouch, the laryngeal saccule.

The saccule of the larynx is a space on each side, between the
false vocal cord and the inner surface of the thyroid cartilage,
reaching upward as high as the upper border of that cartilage,
and its mucous membrane presents the orifices of sixty or
seventy glands. This space has a fibrous capsule. Its laryngeal
surface is covered by the inferior arytenoepiglottic muscle,
or compressor sacculi laryngis, and its external surface by the
thyroarytenoideus and thyroepiglottic muscles.

The muscles of the larynx are divided into extrinsic and
intrinsic—the former will be found under the muscle system
(p. 159). The latter are:

The cricothyroid arises from the front part and sides of the
cricoid cartilage, and is inserted into the lower border of the
thyroid cartilage and the front of its lower cornu. Separating
the inner borders of these two muscles is the central part of
the cricothyroid membrane. The action of the two muscles
is to approximate the cricoid to the thyroid and thus tense the
vocal cords. The nerve supply is from the superior laryngeal.

The thyroarytenoid is divided into two parts, outer and inner.
It arises in front from the angle of the thyroid at its lower
part, and its inner part is inserted into the vocal process and

404. SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

outer surface of the arytenoid cartilage; its outer part, into
the outer border and muscular process of the same cartilage,
above the internal part. The internal part is adherent and
parallel to the true vocal cord; the outer is external to the
sacculus laryngis. ‘Their action is to advance the arytenoid
cartilages and thus relax the vocal cords. The nerve comes
from the inferior laryngeal.

The thyroepiglotticus muscle consists of a considerable number
of the fibers of the thyroarytenoideus prolonged into the aryteno-
epiglottic fold, where some of them become lost, others pass
on to the margin of the epiglottis.

The posterior cricoarytenoid arises from the broad depres-
sion occupying each lateral half of the posterior surface of
the cricoid cartilage; its fibers pass upward and outward, con-
verging to be inserted into the outer angle (muscular process)
of the base of the arytenoid cartilage. The upper fibers are
nearly horizontal, the middle, oblique, and the lower almost
vertical.

The lateral ecricoarytenoid arises from the upper border of the
side of the cricoid cartilage, and is inserted into the muscular

process of the arytenoid cartilage in front of the posterior’

cricoarytenoid muscle.

The arytenoid is a ‘single muscle occupying the posterior
concave surface of the arytenoid cartilage, and is inserted
into the corresponding parts of the opposite cartilage. It
consists of an oblique and transverse set of fibers, the former
arranged like the limbs of the letter X, the latter fibers pass
transversely across. A few of the oblique fibers are continued
around the outer margin of the cartilage, and blend with the
thyroarytenoid muscle in the arytenoepiglottic fold, and are
called the aryepiglotticus muscle.

Actions of the intrinsic muscles: (1) Those which open
and close the glottis. (2) Those which regulate the degree
of tension of the vocal cords.

1. The two posterior cricoarytenoids open the glottis; and
the arytenoid and the two lateral cricoarytenoids close it.

2. The two cricothyroids regulate the tension of the vocal
cords, and elongate them by the same action; the two thyro-
arytenoids relax and shorten them.

The posterior cricoarytenoids separate the vocal cords,
and consequently open the glottis, by rotating the arytenoid

ae tS eee

__

'. THE LARYNX 405

cartilages outward around a vertical axis passing through the
cricoarytenoid articulations, so that their vocal processes and
cords attached to them become widely separated. The lateral
cricoarytenoids by rotating the arytenoid cartilages inward,
close the glottis, and so approximate their vocal processes.
The arytenoids approximate the arytenoid cartilages, and
thus closes the opening of the glottis, particularly at its back
part. The action of the cricothyroids is to raise the anterior
portion of cricoid cartilage—while the extrinsic muscles fix
the thyroid cartilage—this action depresses the back of the
ericoid cartilage, carrying downward the arytenoid cartilages
with it, and thus produce tension and elongation of the vocal
cords.

The thyroarytenoid shorten the vocal cords by drawing
forward the arytenoid cartilages toward the thyroid cartilage.
But, owing to the connection of the internal portion with the
vocal cord, this part, if acting separately, is supposed to modify
its elasticity and tension, and the outer portion being inserted
into the outer part of the anterior surface of the arytenoid
cartilage, may rotate it inward, and thus narrow the rima
glottidis by bringing the two cords together. (Gray.)

The vessels of the larynx are derived from the superior
laryngeal artery a branch of the superior thyroid artery, and
the inferior laryngeal artery, a branch of the inferior thyroid
artery. The veins are the superior thyroid, which’ empties
into the internal jugular vein, and the inferior thyroid, which
empties into the left innominate vein. The lymphatics of
the larynx are divided into superior and inferior set. The
superior accompany the superior laryngeal artery, pierce the
thyrohyoid membrane and pass the nodes located at the bifurca-
tion of the common carotid artery; the inferior empty into
the deep cervical nodes, a node anterior to the cricothyroid
membrane, and the nodes along the inferior thyroid artery.
The nerves are the internal and external branches of the superior
laryngeal (a branch of the pneumogastric), the inferior or
recurrent laryngeal, a branch of pneumogastric, and sympathetic
filaments, which accompany the laryngeal nerves. The internal
branch of the superior laryngeal supply the mucous membrane,
the external branch of the superior laryngeal innervates the
cricothyroid muscle. The inferior or recurrent laryngeal
nerve innervates all the intrinsic muscles of the larynx except
the cricothyroid and a portion of the arytenoid.

406 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

THE TRACHEA

The trachea is a membranocartilaginous tube, flattened
behind, continuous above with the larynx, and below dividing
into the two bronchi.

The trachea consists of sixteen to twenty incomplete car-
tilaginous rings connected by a fibrous membrane. ‘Their free
ends, which are directed posteriorly, are united similarly and
by plain muscular tissue. Its upper limit is at the sixth cervical,
its lower, opposite the body or upper border of the fifth thoracic
vertebra, and it measures about 45 inches in length; trans-
versely, $ to 1 inch.

The relations are: In front, in the neck, the isthmus of the
thyroid, the sternohyoid and thyroid muscles and the cervical
fascia between them, the arteria thyroidea ima, the inferior
thyroid veins, and the communicating branches between the
anterior jugulars; in the thorax, the manubrium sterni, thymic
remains, the left innominate vein, arch of the aorta, innomi-
nate and left carotid vessels, and the deep cardiae plexus.
Behind is the esophagus. Laterally in the neck, the common
carotids, the lateral lobes of the thyroid, the inferior thyroid
arteries, and the recurrent nerves (in the angles between esopha-
agus and trachea); in the chest, the pleura of each side and the
vagus. The trachea is supplied with blood by the inferior
thyroid arteries, branch of the thyroid axis. The veins empty
into the thyroid venous plexus. The nerves are derived from
the vagus, recurrent laryngeal, and the sympathetic.

THE PLEURA AND MEDIASTINUM

The pleure are two separate serous sacs which invest each
lung to its root and are reflected on to the thoracie walls and
pericardium. That portion of the serous membrane invest-
ing the surface of the lung and extending into the fissures
between the lobes is called the visceral layer of the pleura
(pleura pulmonalis), while the portion lining the inner surface
of the thorax is called the parietal layer of the pleura (pleura
parietalis). The latter is subdivided into the cervical, the
costal, the diaphragmatic, and the mediastinal portions. ‘The

- ‘ > .
Ss eS ee eee,

THE PLEURHZ AND MEDIASTINUM 407

space between the visceral and parietal layers is the pleural
cavity (cavum pleurz), and contains a small amount of clear
fluid. Their is no cavity when the pleure are in a healthy
condition, the two layers being in contact.

The two pleure are distinct from each other, and do not
meet in the median line except behind the second piece of the
sternum. At the root of the lung the visceral and parietal
layer of the same side are continuous, and at the lower part
of the root, a fold, the ligamentum latum pulmonis, runs down
to the diaphragm.

The blood supply of the pleura is derived from the inter-
costal, the internal mammary, the musculophrenic, thymic,
pericardiac, and the bronchial. The veins correspond to
the arteries. The nerves, are the phrenic and sympathetic.
(Luschka.) The lymphatics of the visceral layer empty into
the superficial pulmonary trunks; the lymphatics of the parietal
pleura empty into the intercostal, the diaphragmatic trunks
and the posterior mediastinal nodes.

The structure of the pleura is composed of a fibroelastic
connective tissue, its free surface covered with a single layer
of flat endothelial cells. Subserous tissue fastens the pleure
to the parietes and the lung respectively.

The mediastinum is the space between the two pleural sacs,
and extends anteroposteriorly from the sternum to the spine;
it is divided into a superior mediastinum, above the upper
level of the pericardium; the anterzor, in front of the pericardium;
the middle, containing the pericardium; and the posterior
mediastinum, behind the pericardium.

The superior mediastinum is bounded by the manubrium
sterni in front, the upper four dorsal vertebree behind, and
below by a plane passing from the lower border of the manu-
brium to the lower part of the fourth dorsal vertebra. It
contains the lower part of the sternohyoid and thyroid and
longus colli muscles, the transverse aorta, innominate, left
carotid, and subclavian arteries, the superior cava (upper half),
the two innominate and the left superior intercostal veins,
the vagus, cardiac, phrenic, and left recurrent nerves, trachea,
esophagus, thoracic duct, thymic remains, and lymphatics.

The anterior mediastinum is bounded by the sternum and
the pericardium before and behind, by the pleure laterally.
It runs toward the left, is broader below than above, and

408 SPLANCHNOLOGY, OR* ANATOMY OF THE VISCERA

contains the origins of the triangularis sterni, the left internal
mammary vessels, some areolar tissue containing lymphatics,
and the anterior mediastinal glands.

The middle mediastinum contains the heart and pericardium,
ascending aorta, superior vena cava (lower half), inferior
vena cava (upper part), bifurcation of trachea, pulmonary
vessels, the phrenic nerves, the deep cardiac plexus, the vena
azygos major vein, as. it arches over the right bronchus to
open into the superior vena cava. Some bronchial lymph
nodes are also found in this space. )

The posterior mediastinum is behind the pericardium and
roots of the lungs, and in front of the lower eight dorsal vertebre,
the pleuree bounding it on each side, the posterior surface of
the diaphragm below. It contains the descending part of the
arch, the thoracic aorta, the azygos veins, and vagi, and the
splanchnic nerves, esophagus, thoracic duct, and some lymphatic
glands.

THE LUNGS (PULMONES)

The lungs are the essential organs of respiration; they are
situated in the right and left sides of the thorax, covered by
the visceral portion of the pleura; filling the cavity, with the
exception of the intervening mediastinum, containing the
heart, surrounded by the pericardium, the aorta, pulmonary
artery, esophagus, thoracic duct, precava and posteava, and
the nerves, arteries, and veins, which pass toward and away
from the interlying structures.

Each lung presents for examination an apex, a base, dia-
phragmatic, costal, mediastinal surfaces, and anterior, posterior,
and inferior borders. It is suspended within the cavity, by
the root and the ligamentum pulmonale. During respiration
the lung, covered by the visceral pleura, is pressed against the
walls of the thorax interlined by the parietal pleura, and friction
is prevented by a small amount of fluid, within the pleural
cavity which continually bathes the approximating surfaces.

The apex (apex pulmonis) is rounded, and extends about one
inch to two inches above the anterior end of the first rib.
It is grooved by the subclavian artery on the left side, but
on the right side the impression of the innominate vein is the
most prominent groove seen.

7-7". =a

THE LUNGS 409

The Surfaces.—The base (facies diaphragmatis) is concave,
broad, and surrounded by the sharp inferior border. It lies
in relation with the superior surface of the diaphragm, which
separates the right lung from ‘the convex surface of the right
lobe of the liver, and the left lung from the superior surface
of the left lobe of the liver, the fundus of the stomach, and
the spleen. Laterally and behind the thin sharp margin of
the lung projects for some distance into the costophrenic sinus
of the pleura, found between the lower ribs and the diaphragm.
The costal or thoracic surface is convex and smooth. ‘The
right lung presents a a Y-shaped fissure, which divides it into
three lobes; the left lung is crossed by a single fissure, dividing
it into two lobes.

The Inner or Mediastinal Surface.—The left surface pre-
sents the cardiac depression, which receives the left ventricle,
covered by the pericardium; above this is the hilum (root of
the lung), and passing down around the margins of the latter,
two layers of pleura fuse and form the ligamentum pulmonale,
extending from the lower aspect of the hilum to the inferior
border, one to two inches posterior to the interlobar fissure.
Immediately above the hilum is seen a large furrow for the
transverse portion of the arch of the aorta, and extending
upward from this toward the apex is a groove for the left
subclavian artery; a slight impression anterior to the latter
and approaching the margin of the lung lodges the left innomi-
nate vein. Behind the hilum and extending downward and
slightly backward is the groove for the descending portion
of the thoracic aorta, and in front of this is a slight impres-
sion for the esophagus, near the base of ite: lung, showing
that the esophagus is anterior and to the left of the aorta,
just before the former pierces the diaphragm. The right
surface shows, anterior to the hilum, the cardiac depression,
which receives the right ventricle of the heart, covered by the
pericardium. Immediately above the hilum is an arched
furrow for the vena azygos major vein; as it arches forward
above the right branches to empty into. the superior vena
cava, then running upward and outward below the apex is
a wide groove for the superior vena cava and right innominate
vein; and nearer the apex and behind the vein is a second
depression for the innominate artery. Sometimes a slight

410 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

impression is seen for the esophagus song the pectauee part
of the internal surface.

_ Borders.—The posterior border Gnae oonen tenes is convex
and broad, and much longer ‘than the anterior border, and

fits into the deep grooves on either side of the spinal column. -

The inferior border (margoinferior) is sharp and separates
the costal and diaphragmatic surfaces. It extends behind
into the costophrenic sinus of the pleura.

The anterior border is thin and sharp, overlaps the peri-
cardium and extends in front into the costomediastinal sinus
of the pleura. The anterior border of the right lung is almost
vertical; that of the left shows, at the anterior part of the
cardiac ‘depression, an angular notch, the incisura cardiaca,
into which the left ventricle of the heart, covered by the peri-
cardium is received. Just below this notch a projection of
the upper lobe of the lung comes forward overlying the apex
of the heart; it is called the lingula pulmonis.

Fissures and Lobes.—The left lung is divided into two lobes,
an upper and a lower, by an oblique fissure, which extends
from the outer to the inner surface of the lung both above
and below the hilum. The right lung is divided into three
lobes, an upper, middle, and lower, by an oblique fissure,
separating the lower and middle lobes, a horizontal fissure
separating the upper and middle lobes. The oblique fissure
corresponds to the left fissure with the exception that it cuts
the inferior border of the lung three inches behind its anterior
inferior angle, whereas the left cuts the border an inch behind
its extremity. The horizontal fissures cuts the anterior border
of the lung at the level of the sternal end of the fourth costal
cartilage, on the inner surface, and extends backward to the
hilum of the lung.

The right lung is heavier and larger, also shorter and not
so broad as the left.

The Root of the Lung (Radix Pulmonis) lies a little above the
centre of the mediastinal surface, and approaches nearer to the
posterior than its anterior border. It transmits the bronchus,
the pulmonary artery, the two pulmonary veins, usually, the
bronchial arteries and veins—the former supply the bronchi and
lungs with blood—the pulmonary plexus of nerves, lymphatics,
the bronchial lymph nodes, and areolar tissue, surrounded
by a reflection of the pleura which fuses with the pericardium

THE BRONCHI 411

at this point. The relations of the structures within the root
are: From above downward, on the right side, the bronchus,
the pulmonary artery, pulmonary veins; the left side, pulmonary
artery, bronchus, pulmonary veins. On the right side only the
eparterial branch of the bronchus lies above the pulmonary
artery.

The true weight of the human lungs as ascertained in the
bodies of criminals executed by electricity, in which the mode
of death is attended by a nearly bloodless condition of the
lungs, is 215 grams (73 ounces) for the left lung and 240 grams
(83 ounces) for the right lung (EK. A. Spitzka, Amer. Jour.
of Anat., ili, i, p. v). Ordinarily, with the vascular channels
more or less filled with blood and serum, the two lungs to-
gether weigh about 42 ounces, the right lung being 2 ounces
heavier than the left, but much variation is met with according
to the amount of blood or serous fluid they may contain. The
lungs are heavier in the male than in the female. The specific
gravity of the lung tissue varies from 0.345 to 0.746. (Gray.)

The color of the lungs at birth is a pinkish white; in adult
life, a dark slate color, mottled in patches; and as age advances
this assumes a black color. (Gray.)

The lungs are composed of an external serous coat, sub-
serous areolar tissue, and parenchyma, consisting of the lobules
($ inch to 14 inches in size), the terminal bronchioles ending
in the alvei, air sacs, or infundibula and the alveoli or saccules;
the ramifications of the bronchial and pulmonary arteries,
lymphatics and nerves. These are connected by fibroelastic
tissue... The blood supply of the lungs is received from the
bronchial artery, a branch of the thoracic aorta, and the pul-
monary arteries, which are the nutrient vessels of the respiratory
epithelium. The bronchial arteries supply the bronchi, bron-
chioles, and interlobular tissues, as well as the walls of the
pulmonary vessels. The right bronchial veins empty into the
vena azygos major, the left bronchial veins empty into the left
superior intercostal vein or the vena hemiazygos accessoria vein.

THE BRONCHI

The Right.—Enters the hilum of the lung. About one inch
from the trachea it gives off a branch above the pulmonary

412 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

artery, and is, therefore, named the eparterial, which ramifies
through the superior lobe. The hyparterial branches are
given off below the pulmonary artery and hence the name.
Ventral and dorsal branches are given off from the main bronchi,
increasing in number and decreasing in size, like the branches
of a tree, to end in the bronchioles throughout the lobules of
the lung.

The Left.—Has no eparterial branch. The first hyparterial
branch is given off 2 inches from the bifurcation of the trachea,
and has the same distribution poeas its branches as the
right side.

The right bronchus lies belsint the superior cava and the
ascending portion of the arch of the aorta, has the vena azygos
major vein above and the pulmonary vessels below. The
left bronchus passes in front of the descending aorta, has the
pulmonary artery above it and the vein below. The phrenic
nerves pass in front of the right and left bronchus, and the
vagus (pneumogastric) nerves pass behind them.

The bronchi are innervated by nerves derived from the
sympathetic and vagi nerves, through the pulmonary plexus.

Their structure resembles the trachea, only that the cartilagi-
nous rings become thinner and are replaced by an increase in
the muscular coat, as they approach the terminal bronchioles.
The alveoli rest on a basement membrane of elastic tissue,
surrounded by a capillary plexus formed by the pulmonary
arteries and veins.

THE ORGANS OF DIGESTION
THE MOUTH. ORAL OR BUCCAL CAVITY (CAVUM ORIS)

The mouth is the upper part of the alimentary canal. It
is bounded by the lips, cheeks, tongue, hard and soft palate,
alveolar processes of both jaws, with their contained teeth,
and opens behind, through the isthmus faucium, into the
pharynx. It is lined by mucous membrane continuous in
front with the skin, behind with that of the fauces, its epithe-
lium being stratified.

The teeth in the human subject are erupted in two sets,
a temporary or deciduous, or milk teeth, and a permanent

THE MOUTH 413

or succedaneous set. The former are 20 in number, 10 in each
jaw; the latter, 32, 16 each above and below. Each tooth is
made up of three parts: the root, consisting of one or more
fangs, contained in the alveolus; the crown, or body, above
the gum; and the neck, between the two. The alveolar peri-
osteum is reflected on to the fang as far as the neck.

The twenty temporary teeth are divided into 4 incisors, 2
canines, and 4 molars above and below. The 32 permanent
teeth are, 4 incisors, 2 canines, 4 bicuspids, and 6 molars in
each jaw. The temporary teeth are similar to but smaller
than the permanent; of the temporary molars, the hinder one
is the largest of all, and its place is afterward taken by the
second permanent bicuspid.

Of the permanent teeth the incisors are the 8 central cutting
teeth, 4 each above and below, the former being the larger.
They are bevelled at the expense of the posterior surface.
The canines (cuspidati) are 2 in each jaw, being situated 1
behind each lateral incisor, the upper and larger being called
the eye teeth: The bicuspids (premolars or false molars),
4 in each jaw, lie 2 each behind the canines, the upper being
the larger. The molars (true molars or multicuspidati) are
the largest teeth, and number 6 in each jaw, 3 each behind the
posterior bicuspids above and below. They présent 4 tubercles
on the upper, 5 on the lower crowns, and the root is subdivided
into from 2 to 5 fangs. The first molar is the largest and
broadest, the second smaller, and the third (wisdom tooth)
the smallest.

A vertical section of a tooth shows it to be hollow, the cavity
being continuous with th® aperture in the fang and filled up
with the soft dental pulp, and is hence called the pulp cavity.
The pulp is sensitive, highly vascular, and consists of con-
nective tissue, with cells, vessels, and nerves. The hard
substance of each tooth consists of three parts: the wory,
or dentine, the enamel, and the crusta petrosa, or cement.

Eruption.—The teeth are erupted by the absorption of the
bone between them and the gum, as well as that covering the
labial side of the crown. Thus they are not an upward growth
of the tooth, but appear as a result of the absorption of the
bone around the crown. The bone covering the lingual surface
is more slowly absorbed, as it protects the permanent tooth
germ beneath.

414 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

The eruption of the temporary teeth commences at the
end of the seventh month, and is Beier Fn: about the end
of the second year.

The period of eruption of the tonapeeiey teeth are (C. S
Tome):

Lower central incisors. . .. 6 to 9 months.
Upper incisors .. 8 to 10 months.
Lower lateral incisors aid frat: molars 15 to 21 months.
CaO oa), Sse ee ae 16 to 20 months.
Second molars . . . .... . 20 to 24 months.

The period of eruption of the permanent teeth are:

First amolars: "> ux meee ae > years.
Two middle incisors . . ... 7th year.
Two lateral incisors . . ... Sth year.
Firstbicuspid rin ek: ae Re 9th year.
Second bicuspid . . . . . 10th year.
Canine... 25 0) po. Se eto
Second molars ... . . . . 12th to 13th year.
Third molars >). ln ss) OS. ee eee

THE TONGUE (LINGUA)

The tongue is the organ of the special sense of taste, also

assisting in insalivation, mastication, and deglutition. It

is situated in the floor of the mouth, in the interval between
the horizontal rami of the mandibf. It is attached to the
hyoid bone at the base by the genioglossus and hyoglossus
muscles and the hyoglossal membrane; with the epiglottis
by three folds, the glossoepiglottic folds, of mucous membrane;
with the soft palate by means of the anterior pillars of the
fauces; and with the pharynx by the superior constrictor
muscles and the mucous membrane.

The muscles controlling the tongue are the extrinsic, which
are inserted into the tongue, their terminal fibers contained
within the substance, namely: The styloglossus, the hyo-
glossus, the palatoglossus, the genioglossus, and part of the
superior constrictor of the pharynx (pharyngoglossus). The
intrinsic muscles of the tongue are: The superior lingualis,

THE TONGUE 415

the chondroglossus, the transverse lingualis, the vertical
lingualis, and the inferior lingualis. ‘These muscles are invested
by a submucous fibrous layer, covered by a mucous membrane.
It consists of symmetrical halves, separated from each other
by a fibrous septum. Each half of muscular fibers is arranged
in various directions, containing many glands, and fat, and
supplied by vessels and nerves. For purposes of description
the tongue is divided into, a body, base, apex, dorsum, margins,
and inferior surface.

The body (corpus lingue) is composed of striated muscle
and forms the greatest bulk of the organ.

The base, or root (radix linguse), is directed backward, is
convex and held to the hyoid bone by the hyoglossus and
geniohyoglossi muscles and membrane; with the epiglottis
by the glossoepiglottic folds, also attached to the soft palate
by the anterior pillars of the fauces, and to the pharynx by
the palatopharyngei muscles, and the mucous membrane.

The apex (apex linguz) is thin and narrow, resting against
the inner surface of the lower incisor teeth.

The dorsum (dorsum linguze) is convex from before back-
ward, when at rest. It presents for examination a median
longitudinal raphé (sulcus medianus linguz), which ends in
a depression at the posterior part; the foramen cecum (foramen
cecum lingue Morgagni), from which a _ shallow groove
passes outward and forward on each side to the lateral margins;
this is called. the sulcus terminalis of His. The projections
of papillze are seen through the stratified squamous epithelial
cells. They are: (1) The filiform (papille filiformes), small
and scattered over the apical two-thirds (dorsum and margins)
of the tongue; (2) the fungiform papille (papillee fungiformis),
scattered (but less numerous than the filiform) over the
dorsum, and are more numerous at the sides and apex (they
are readily recognized by their large size and deep red color);
(3) the cireumyallate papille (papille vallate) are large,
but only eight to twelve in number. They are arranged in
a V-shaped manner just in front of the foramen cecum, and
the sulcus terminalis.

The arteries of the tongue are derived from the lingual,
the facial, ascending pharyngeal (all branches of the external
carotid artery). The veins open into the internal jugular.
The lymphatic vessels from the anterior half of the tongue,

416 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

drain into the submaxillary nodes. Those draining the posterior
half end in the deep cervical nodes; along the internal jugular
vein. Across the anterior two-thirds of the tongue there
is no lymphatic connection between the two sides; in the
posterior one-third .there is free connection, due to absence
of the septum here.

The nerves of the tongue are five in number in each half—
the lingual, a branch of the inferior maxillary division of the
trigeminal innervates the papillze on the sides and anterior
part of the tongue; it is the nerve of ordinary sensibility for
the anterior two-thirds. The chorda tympani is the nerve
of taste for the same region, and accompanies the lingual
enclosed in the same sheath; the lingual branch of the glosso-
pharyngeal innervates the mucous membrane of the base,
sides, and circumvallate papille, supplying them with sensor
and gustatory filaments; the hypoglossal nerve is distributed
to the muscular substance of the tongue, supplying them
with motor filaments. Sympathetic filaments are furnished
from the nervi molles on the lingual and other arteries to the
tongue. Some of the nerves end free between the cells of
epithelium; others terminate as end organs (Meissner’s cor-
puscles and the end bulbs of Krause), and in taste buds as
sensor dendrites. (Gray.)

The palate forms the roof of the mouth, at consists of a
front part or hard, and a back part or soft palate. The peri-
osteum of the hard palate (see Bones) is covered by and
intimately connected with the mucous membrane of the mouth.
In the middle line is a raphé ending in front at a small papilla,
which marks the anterior palatine fossa which receives the
terminal part of the anterior palatine and nasopalatine nerves.
The mucous membrane is pale and corrugated, covered with
squamous epithelium, and furnished with a number of palatal
glands which lie between it and the bone.

The soft palate partially separates the mouth and pharynx.
It consists of muscular, connective, and adenoid tissue, with
vessels, nerves, and mucous glands, all enclosed in a fold of
mucous membrane. Above it is joined to the back of the
hard palate; laterally it blends with the pharynx; below it
is free; in front it is concave, with a median ridge; and behind
it is convex. Its mucous membrane is continuous with that
of the roof of the mouth and of the posterior nares.

oe

SS SS SL eT Cl eelUCU

‘

THE SALIVARY GLANDS 417

From its lower border a conical process depends, the woula,
from whose base descend the pillars of the soft palate, the
anterior, formed by the palatoglosst muscles, to the sides of
the base of the tongue; the posterior, formed by the palato-
pharyngei, to the sides of the pharynx. These pillars are covered
by mucous membrane and separated below by the tonsil, the
space being called the isthmus of the fauces. The muscles of
the soft palate are five on each side, and lie in the following
relative position from before backward: The palatoglossus,
tensor palati, anterior fasciculus of palatopharyngeus, levator
palati, azygos uvule, and lastly the posterior fasciculus of the
palatopharyngeus.

The tonsils (tonsilla palatina) are two in number, situated
on each side of the fauces, and lie between the anterior and
posterior palatine pillars, and are about 3 inch long and 4
inch wide and thick, but vary much in size. Externally they
are separated by the superior constrictors from the internal
carotid artery, which is about 1 inch away from it, also lies
to the outer side, and ascending pharyngeal arteries; internally
they project into the fauces, and present 12 or more orifices
which lead into the crypts in their substance. Around the
crypt walls are numerous lymphoid follicles consisting of
adenoid tissue. The arteries supplying the tonsil are: The
dorsalis linguee, a branch of the lingual; the ascending palatine
and tonsillar from the facial; the ascending pharyngeal from
the external carotid; the descending palatine, a branch of the
internal maxillary, and a small meningeal branch. ‘The veins
empty into the internal jugular or facial vein, after passing
from the tonsillar plexus (on the external surface of the tonsil),
to the pharyngeal plexus, then the pterygoid plexus. The
lymphatic vessels drain into the submaxillary and retro-
pharyngeal nodes and thence to the deep carotid nodes. The
nerves of the tonsil are the filaments derived from the tonsillar
plexus, formed by branches from the glossopharyngeal joining
with branches of the pharyngeal plexus.

THE SALIVARY GLANDS

There are three pairs, parotid, submavillary, and sublingual.

The parotid gland, the largest, weighs $ to 1 ounce, and

lies on the face below and in front of the ear. Its outer surface,
2d

418 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

lobulated, is covered by the skin and fascia, and partly by the
platysma and several lymphatic glands; in front it runs over
the masseter, is grooved for the ramus of the lower jaw, and
extends beneath it, between the two pterygoids; above it is
bounded by the zygoma; below, by the-angle of the jaw and a
line joining it with the mastoid process; behind, by the external
meatus, mastoid process, and sternomastoid. The internal
surface sends two processes into the neck—one behind the
styloid process and beneath the mastoid process and sterno-
mastoid; another in front of the styloid process, into the back
of the glenoid cavity behind the jaw. Embedded in the gland
are found the external carotid, posterior auricular, temporal,
transverse facial, and internal maxillary arteries, the temporo-
maxillary vein and a branch from it to the internal jugular,
the facial nerve with its branches, and the auriculotemporal
and great auricular nerves. The internal carotid artery and
internal jugular vein lie under its deep surface.

The duct (Stenson’s) is about 23 inches long and 4 inch
in diameter, and opens opposite the second molar tooth, thence
runs backward beneath the mucous membrane, through the
buccinator, and across the masseter to the front of the gland.
It commences by numerous branches, and on the masseter
receives the duct of a detached part of the gland, the socia
parotidis, which sometimes is found beneath the zygomatic
arch. Its epithelium is columnar.

The submaxillary gland is of an irregular form, weighs about
2 drams, and lies below the jaw and above the digastric muscle.
It is covered by the skin, platysma, and fascie, and grooves
the inner surface of the lower jaw. It lies on the mylohyoid
(partially embracing this muscle), hyoglossus, and styloglossus,
and has in front of it the anterior belly of the digastric. Behind,
the stylomaxillary ligament separates it from the parotid,
and the mylohyoid (its superficial part) from the sublingual
gland in front. The facial artery grooves its upper and back
part.

The submaxillary duct (Wharton’s) is 2 inches long, and
opens at the top of a papilla close to the frenum lingue. Thence
it runs back between the sublingual gland and the geniohyo-
glossus, then between the mylohyoid and the hyoglossus and
geniohyoglossus.

The sublingual gland, the smallest of the salivary glands,

THE PHARYNX 419

lies at the side of the frenum linguz and against the inner
surface of the lower jaw, beneath the mucous membrane.
It is almond-shaped, weighs 1 dram, and its ducts (of Rivinz),
ten to twenty in number, open separately, one or two joining
to form the duct of Bartholin, which joins Wharton’s duct.
It is in relation below with the mylohyoid; in front, with its
fellow and the lower jaw; behind, with the submaxillary gland;
internally the gustatory nerve and Wharton’s duct separate
it from the geniohyoglossus.

The arteries supplying the parotid gland, are derived from
the external carotid, and the branches given off within its
substance; the blood supply of the submaxillary gland is from
the facial and lingual; the sublingual gland from the sublingual
artery, a branch of the lingual, and the submental, a branch
of the facial artery. The veins of the parotid empty into the
external jugular; those from the submaxillary gland open into
the facial and lingual; the veins from the sublingual gland
open into facial and lingual through the submental and sub-
lingual veins. The lymphatics of the parotid drain into the
external jugular and the upper deep cervical nodes; the sub-
maxillary into the submaxillary nodes; the sublingual lymphatics
drain into the submental nodes, and the efferents pass to the
submaxillary nodes. The nerves of the parotid gland are the
auriculotemporal, nervus intermedius, great auricular, and
from the sympathetic plexus found on the external carotid
artery; the innervation of the submaxillary is from the chorda
tympani and lingual (a branch of the inferior maxillary divi-
sion of the trigeminus), through the submaxillary ganglion
and its sympathetic filaments; the sublingual is supplied by
branches from the lingual nerve, and sympathetic filaments,
derived from the chorda tympani through the sublingual
plexus. The sympathetic filaments are all efferent.

THE PHARYNX

- The pharynx is a musculomembranous tube, conical in
shape, between the oral cavity and the esophagus; communi-
cating with the posterior nares, the oral cavity, the larynx,
the two Eustachian tubes, the esophagus. It is attached above
to the periosteum of the petrous portion of the temporal bone

420 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

and the basilar process of the occipital bone. The raphé of
the constrictor muscles is attached to the pharyngeal tubercle
of the basilar process of the occipital bone. It is bounded above
by the body of the sphenoid and basilar process of the occipital;
below, it is continuous with the esophagus; anteriorly, it is
incomplete, and is attached to the Eustachian tube, the internal
pterygoid plate, the pterygomandibular ligament, the posterior
portion of the mylohyoid ridge, the mucous membrane of the
mouth, the base of the tongue, the hyoid bone, the thyroid
and cricoid cartilages; posteriorly, the prevertebral fascia,
and the areolar tissue connects it to the cervical portion of
the vertebral column, anterior to the longus colli and rectus
capitis anticus muscles, areolar tissue is contained in the
retropharyngeal space; laterally, it is connected to the styloid
process and its muscles. The internal jugular veins; the internal
and common carotid, the ascending pharyngeal arteries, and
the glossopharyngeal, the vagus, hypoglossal, and sympathetic
nerves, lie externally above, with a small portion of the internal
pterygoid muscles. The constrictor muscles surround it and
aid in deglutition. It is 45 inches long, and for purposes of
studying, divided into a nasal, oral, and laryngeal portion.

The nasal part, or nasopharynx, lies posterior to the nares
and above the soft. palate. In front are the posterior nares
(choanee); behind, the pharyngeal tonsil, consisting of lymphoid
tissue, seen above the orifices of the Eustachian tubes in the
median line. Below the vault of the pharynx is an irregular
flask-shape depression of the mucous membrane, called the
pharyngeal bursa, a possible vestige of the pharyngeal tonsil.
The floor of the nasopharynx is continuous with the nasal
fossee, anteriorly, and behind is the sloping portion of the soft
palate. On its lateral wall is the orifice of the Eustachian
tube, level with the inferior turbinated bone and one-third to
one-half inch posterior to its dorsal extremity. Behind the
Eustachian tube is the Eustachian cushion, caused by the
inner extremity of the cartilage of the tube, which elevates
the mucous membrane. Extending from the lower portion of
the cushion is the salpingopharyngeal fold, and from the upper
part passes the salpingopalatine fold. The deep recess behind
the cushion is called the fossa of Rosenmiiller (recessus
pharyngeus).

The oral part, or oralis pharyngis, extends from the soft

a

:

THE ESOPHAGUS 421

palate to the level of hvoid bone. It opens into the oral cavity,
through the fauces, bounded on either side by the anterior °
and posterior pillars, between which are the tonsils.

The laryngeal part is continuous with the oral portion
above, and below at the level of the cricoid cartilage is con-
tinuous with the esophagus. Anteriorly, it presents the
aperture of the larynx, bounded in front by the epiglottis,
and laterally by the arytenoepiglottic folds. On either side of
the aperture is the sinus pyriformis, bounded internally by the
arytenoepiglottic folds and laterally by the thyroid cartilage
and thyrohyoid membrane.

The pharynx is lined with mucous membrane continuous
with that lining the Eustachian tube, the nasal fosse, the
mouth, and the larynx. In the nasopharynx it is covered by
stratified ciliated epithelium; in the buccal and laryngeal
portions it is of the stratified squamous variety.

The arteries are derived from the ascending phary ngeal,
ascending and descending palatine, the tonsillar. The veins
empty into the pharyngeal and facial plexuses. The lymphatics
drain into the retropharyngeal nodes in the retropharyngeal
space and the upper deep cervical nodes.

THE ESOPHAGUS

The esophagus is the tube connecting the pharynx with
the stomach, and extends from the level of the sixth cervical
vertebra through the diaphragm, entering the stomach oppo-
site the tenth or eleventh dorsal vertebra, a distance of 9 or
10 inches, and from the incisor teeth to the beginning of the
esophagus is about 6 inches; thus making the distance from
the incisor teeth to the cardiac opening of the stomach 15 to
16 inches. At first in the median line it runs to the left as
far as the root of the neck, becomes again mesial, and lastly
turns toward the left to pass through the esophageal orifice
in the diaphragm. It. also corresponds to the cervical and
dorsal curves of the spine. It is the narrowest part of the
alimentary canal, and presents two constrictions, one at its
commencement, the other at the diaphragm.

IN THE NECK it is in relation, in front, with the trachea; behind
with the longus colli and spinal column; laterally, with the

422 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

common carotid arteries and part of the thyroid gland. Between
it and the trachea ascend the recurrent laryngeal nerves.

IN THE CHEST it is in relation, in front, with the trachea,
left bronchus, arch of the aorta and left carotid artery, and
pericardium; behind, with the spine, longus colli, thoracic duct,
and a portion of the descending thoracic aorta, where the
esophagus crosses from right to left before piercing the dia-
phragm; laterally, with the pleure, and on the right side the
large azygos vein, and on the left the aorta except near the
diaphragm, where the aorta lies to the right side. The right
vagus is behind and the left in front of the esophagus, but at
first each is on the corresponding side.

The arteries are derived from the inferior thyroid, a branch
of the thyroid axis of the subclavian; from the esophageal
and bronchial arteries, branches of the descending thoracic
aorta; the gastric from the celiac axis, and the left inferior
phrenic of the abdominal aorta. The veins form a plexus
on the outer side of the esophagus, emptying into the thyroid,
vena azygos major, and the gastric vein. Thus the portal
vein can communicate with the systemic veins. The lymphatics
drain into the inferior left cervical nodes, and the nodes of
the posterior mediastium. ‘The nerves are derived from the
vagus and sympathetic system. They form the anterior and
posterior esophageal plexuses.

THE PERITONEUM

The peritoneum is a closed serous sac, which invests more
or less completely the contents of the abdominal and pelvic
cavities, sending in processes or diverticula between the adjacent
viscera. These processes are attached to the surfaces of the
viscera, forming their investment, and serving also to separate
and allow a free movement between them without friction.
Moreover, they confine the viscera to their proper relative
positions.

The peritoneum is very thin, the attached surface being
rough, the free, smooth and moist, and covered with a layer
of mesothelium. That part which is attached'-to. the inner
surface of the abdominal walls is called the parietal layer,
while that investing the viscera constitutes the visceral layer.

:

THE PERITONEUM 423

(Norre.—The adult peritoneum will never be fully under-
stood until the student acquires a thorough knowledge of the
development of the intestinal canal in the embryo, and the
books on embryology should be carefully studied on this
subject.)

The General Arrangement of the Peritoneum.—Starting from
the anterior abdominal wall, in the median line, the peritoneum
passes around on the right side to invest completely the lower
part of the cecum and the vermiform appendix, but only parti-
ally investing the rest of the cecum, covering its front and sides,
the back part being very often uncovered. It partially invests
the entire ascending colon in a similar manner. Quite often,
however, the back part of the cecum is also covered by the
peritoneum, which thus forms a mesocecum. It now covers
the lower part of the front of the right kidney and the front
of the third portion of the duodenum, excepting a transverse
zone, passes thence to the spine, and forming the right side
of the mesentery invests the jejunum and ileum, and returns,
as the left layer of the mesentery to the spine, tl us completing
the structure. The peritoneum now crosse. *ge lower part
of the left kidney, invests the descending colon in a manner
similar to that on the right side, forms a long sigmoid meso-
colon, and returns to the front of the abdomen.

Starting in the median line behind at the sacral angle we

-may trace the peritoneum downward to invest completely the

rectum in its upper part and partially invest it in its second
portion, covering it in front, and laterally, and lower down,
only in front, and at a point about 6 to 8 cm. above the anus
leaves the gut altogether. It is then reflected on to the base
and upper part of the bladder in the male, forming the recto-
vesical pouch. This pouch presents on each side a fold, the
plica semilunaris. From the apex of the bladder it ascends,
investing the urachus and obliterated hypogastric artery. on
each side. In the female it passes from the rectum to the upper
part of the vagina, forming the rectovaginal pouch (or cul-de-
sac of Douglas), which presents plicze semilunares similar to
those found in the rectovesical pouch in the male. It then
covers both surfaces of the uterus, and forms the broad liga-
ments, investing the Fallopian tubes to the fimbriated ends,
where it becomes continuous with their mucous membrane.

Above, the peritoneum runs on the under surface of the

-_ = ee

424. SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

diaphragm as far back as the esophageal opening, and near
that opening meets the process of the lesser sac, which lies on
the posterior surface of the liver. It passes to the liver, forming
the superior layers of the lateral and coronary ligaments.
At the anterior border of the liver it is reflected on to its under
surface, and at the transverse fissure it meets the posterior
layer of the lesser or gastrohepatic omentum from the lesser
sac, and passes with it to the lesser curvature of the stomach
as the anterior layer, thus completing the lesser omentum.
Thence it passes over the anterior surface of the stomach
to the greater curvature, then down to the greater omentum.

To the right from the quadrate lobe it invests the gall-
bladder to a variable degree, the under surface of the right
lobe of the liver passing back to the posterior surface of the
liver as far as the coronary and right lateral ligaments, of
which it forms the lower layer (the layers are separated by
a considerable space).. It then turns down over the diaphragm
to the front of the second portion of the duodenum, and the
upper part of the right kidney, forming here the fold known
as the hepatorenal ligament. Lastly, it invests the hepatic
flexure of the colon, and proceeds to the right colon in the
manner previously described.

To the left it covers the entire under surface of the left
lobe of the liver back to the left lateral ligament, of which it
forms the inferior layer; there it turns down on the diaphragm,
to the left of the esophageal opening.

Tracing to the left the anterior layer of the lesser omentum,
the peritoneum covers the front and left side of the esophagus
and left end of the stomach, passing thence to invest the spleen,
and forming the anterior layer of the gastrosplenic omentum.
Passing from the diaphragm to the stomach to the left of the
gullet, there is formed the gastrophrenic fold or ligament,
and between the diaphragm and splenic flexure the costocolie
ligament.

The lesser sac of the peritoneum is a process which lines the
space bounded by the posterior and inferior surfaces of the
Spigelian lobe of the liver and the posterior wall of the stomach
and the upper surface of the transverse colon. It commnuni-
cates with the greater sac by means of the foramen of Winslow,
which is bounded in front by the lesser omentufh, with the
portal vein and hepatic artery and duct between its layers,

*

THE PERITONEUM 425

behind by the vena cava inferior and right crus of the dia-
phragm, above by the lobus caudatus, below by the duodenum
and hepatic artery. From this point the lesser sac lines the
posterior abdominal wall, and adheres to the back of the
greater sac except where the stomach comes between. Above
it passes behind the liver, between the Spigelian lobule and
the back part of the diaphragm, to meet the process from the
greater sac already described. Here it is attached to the
transverse fissure and the fissure of the ductus venosus, cover-
ing the esophagus behind and on the right. At the transverse
fissure it passes to the lesser curvature of the stomach, forming
the posterior layer of the lesser or gastrohepatic omentum,
the anterior layer coming from the greater sac.

It then invests the back of the stomach, and descends from
the great curvature in front of the transverse colon and small
intestine to a variously greater or less extent. Turning upon
- itself, it ascends, thus forming the internal layers of the great
omentum, as far as the transverse colon, whose upper surface
it invests, and passes thence to the spine, thus forming the -
upper layer of the transverse mesocolon. It now passes up-
ward over the front of the pancreas, celiac axis and its branches,
upper part of left kidney, the left suprarenal capsule, and
that part of the diaphragm between the aortic and caval
openings, and is continuous with that part of the lesser sac
lining the space back of the liver, already described. Traced
to the left over the pancreas, the peritoneum is reflected to
the hilum of the spleen, and thence to the stomach, forming
the posterior layer of the gastrosplenic omentum. Traced
to the right, it is reflected from the extreme end of the pan-
creas on to the back of the first portion of the duodenum, and
becomes continuous with that covering the posterior surface
of the stomach.

The anterior layer of the lesser omentum invests the front
of the stomach to the greater curvature, from which it descends
in front of and with the posterior layer, and thus down in
front of the transverse colon and small intestine to a variable
degree. These two layers are closely adherent to each other
in adults and turn backward upon themselves to ascend to
the transverse colon, thus completing the great omentum.
Those layers, therefore, of the great omentum, which are con-
tributed by the lesser sac, are continued within those from the

426 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

greater sac. At the transverse colon the layers of the greater
omentum separate and enclose the gut, meeting behind and
completing the transverse mesocolon, which extends to the
lower border of the pancreas. Here the inferior layer (from
the greater sac) runs down along the posterior abdominal
wall and blends with the mesentery as described, and the
superior layer (from the lesser sac) proceeds as already men-
tioned.

The peritoneum forms certain pouches or cul-de-sacs, which
are essential to the surgeon, owing to their being sites for
the possible occurrence of retroperitoneal or intra-abdominal
hernia. They are the lesser sac; through the foramen of
Winslow, the duodenal fossz; the pericecal fosse; and the
intersigmoid fosse.

The duodenal folds, or fosse: (1) The inferior duodenal
fossa, or fossa of Treitz, is present in from 70 to 75 per cent.

of cases. It is found opposite the third lumbar vertebra .

on the left side of the ascending or fourth portion of the
. duodenum; and is bounded by a thin free fold of peri-
toneum, called the inferior duodenal fold. (2) The superior
duodenal fossa is present in about 40 to 50 per cent. of the
_ eases. It is found to the left of the duodenum, bounded by
the thin free edge of the superior duodenal fold; to the right
it is blended with the peritoneum covering the ascending
duodenum, and on the left with the peritoneum covering the
perirenal tissues; behind is the second lumbar vertebra. (3)
The duodenojejunal fossa, or mesocolic fossa, is seen by pulling
the jejenum downward and to the right, after raising upward the
transverse colon. It is circular in shape, bounded above by
the free margins of peritoneum, called right and left duodeno-
mesocolic ligaments. Above is the body of the pancreas, to
the right the aorta, and to the left lies the left kidney, behind
the left renal vein. It is present in about 15 to 20 per cent.
of the cases. (4) The paraduodenal fossa, or fossa of Laudzert,
is very seldom seen, and usually in the infant when present.
It is found to the left of the ascending duodenum, the fold
of peritoneum bounding it above is formed by the inferior
mesenteric vein. Its lower boundary is a free edge, called the
mesentericomesocolic fold. (5) The retroduodenal fossa is a
peritoneal cul-de-sac, first described by Jonesco in 1893, and

ee Bb

THE STOMACH 427

is found between the ascending and transverse portions of the
duodenum.

Pericecal folds and fosse are found in the region of the
cecum. (1) The superior iliocolic fossa is found between the
iliocolic fold in front, the mesentery of the small intestine,
the ileum, and a small portion of the cecum behind. It is
a very narrow space. (2) The inferior ileocecal fossa (or ilio-
appendicular) is found behind the angle of junction of the
ileum and cecum. It is bounded by the ileocecal fold, or “ blood-
less fold” of Treves, which is attached by its upper extremity
to the ileum, opposite its mesenteric attachment, while the
lower extremity, passing over the ileocecal junction, is attached
to the mesoappendix, and sometimes the appendix; it is thus
called the ileoappendicular fold. ‘The ileocecal fossa is bounded
above by the posterior surface of the ileum and its mesentery;
in front and below by ileocecal fold, and behind by the upper
part of the mesoappendix. (3) The retrocecal fossa is found
behind the cecum; seen only on raising the cecum. It is the
space found between the superior cecal fold, on the right side,
one edge is attached to parities and extends from the lower
pole of the kidney to the iliac fossa and by the other to the
posteroexternal aspect of the colon and cecum, on the left
side by the inferior cecal fold, which is essentially the insertion
of the mesentery into the iliac fossa.

The intersigmoid fossa is constant in the fetus and during
infancy, seldom seen in the adult. After raising the sigmoid
flexure of the colon it will be seen on the left surface of the
sigmoid mesocolon; a small recess lying on the external iliac
vessels, in the interspace between the psoas and iliacus muscles.
This is the orifice leading to the fossa intersigmoidea, which
lies behind the sigmoid mesocolon, and in front of the parietal
peritoneum.

THE STOMACH (GASTER)

The stomach lies in the epigastrium, left hypochondrium,
and sometimes the mesogastrium. It is the most dilated por-
tion of the alimentary canal. Its shape is pyriform; the left
or larger portion is called the cardia, and below this is the
fundus; the right end is termed the pylorus. The right opening
of the stomach is called the pyloric orifice, and the left the

428 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

esophageal orifice; the former opens into the duodenum, and
the latter into the esophagus. It is 10 to 12 inches in length,
4 to 5 inches in the vertical direction, and weighs 4 to 5 ounces.
Its capacity is from 3 to 6 pints.

The cardiac orifice is the highest part of the stomach, and
lies behind the seventh costal cartilage 1 inch to the left of
the sternum. The pyloric orifice lies about 2 inches to the
right of the mid-line, on a level with the upper border of the
first lumbar vertebra; it is guarded by a valve, the pylorus.
Between the two orifices the stomach is sickle- shaped and
presents an upper concave border, the lesser curvature, and
a lower convex border, the greater curvature. The former
gives attachment to the gastrohepatic or lesser omentum,
the latter affords attachment to the great omentum. The
upper end of the stomach is enlarged 2 to 3 inches to the left
of the cardiac orifice, to form the fundus or great cul-de-sac,
which is connected to the spleen by the gastrosplenic omentum.
The pyloric orifice is anterior and inferior to the fundus, and
is in relation with the quadrate lobe of the liver and belly
wall. The stomach presents two surfaces, an anterosuperior and
posteroinferior.

The relations of the anterosuperior surface are: Diaphragm,
under surface of left lobe of liver (pylorus), quadrate lobe of
liver, abdominal wall, thoracic wall, formed by the correspond-
ing seventh, eighth, and ninth ribs. Posteroinferior surfaces
are: Diaphragm, the gastric surface of the spleen, the left
suprarenal gland, the upper part of the front of the left kidney,
the anterior surface of pancreas, the splenic flexure of colon, and
the upper layer of the transverse mesocolon. These structures
form a shallow cavity on which the stomach rest, and is termed
the stomach bed. The stomach is entirely covered by peri-
toneum, except over a small area close to the cardiac orifice,
on the posteroinferior surface; this area is limited by the lines
of attachment of the gastrophrenic ligament.

The stomach has a serous (peritoneal) coat, a muscular
coat comprising a longitudinal, circular, and oblique layer,
an areolar coat of loose tissue (submucous coat), and a mucous
coat. The latter is thickest near the pylorus, thinnest at the
fundus, and presents, in the empty condition’ of the organ,
numerous ridges, or rug@, which run longitudinally along the
great curvature. Studded over its surface are many small

a

THE STOMACH 429

polygonally-shaped depressions, which are the enlarged mouths
of the gastric tubular glands. These are of two kinds, called
pyloric and peptic glands; some are simply tubular, while
others have several branches opening into a common duct.
The pyloric glands are most numerous at the smaller end,
but the peptic glands are found all over the stomach, the ducts
of the latter being shorter. In the latter, between the base- -
ment membrane and the lining epithelium, are numerous
peptic or parietal cells, the others being known as the central
or chief cells. Between the glands the mucous membrane
contains lymphoid tissue, collected here and there into little
masses resembling the solitary intestinal glands, and called
the lenticular glands. -Beneath the membrane is a muscularis
mucose. The arteries are: To the lesser curvature and part
of the anterior and posterior surfaces, the gastric artery from
the celiac axis, the pyloric from the hepatic; to the greater
curvature and anterior and posterior surfaces, the gastro-
epiploica dextra, from the gastroduodenal, a branch of the
hepatic; the gastroepiploica sinistra from the splenic. The
gastric gives off a branch to the esophagus at the cardiac orifice,
and passing. along the lesser curvature anastomoses with the
pyloric artery. The gastroepiploica arteries anastomose along
the greater curvature, supplying the great omentum. The
vasa brevia, 4 or 5 in number, are derived from the splenic
and pass to the fundus of the stomach, anastomosing thereon,
with the gastric and gastroepiploica sinistra arteries. The
veins accompany the arteries. The gastric and pyloric open
into the portal vein; the gastroepiploica sinistra into the splenic;
the gastroepiploica dextra, the superior mesenteric vein. The
nerves are derived from the vagus, the left supplying the antero-
superior surface, the right the posteroinferior surface. The
sympathetic filaments from the celiac plexus (solar plexus)
join with the vagus to form the plexus of Auerbach and
Meissner; the former is found in the muscular coats, the latter
in the submucous coat. Auerbach’s plexus is formed by fibers
from Meissner’s plexus (Gray).

The lymphatics of the stomach are divided into: (1) The
gastric nodes, which drain the lower end of the esophagus
and the cardiac end of the stomach, emptying into the celiac
nodes; (2) a set that drain the fundus, draining the area supplied
by the vasa brevia and left gastroepiploica sinistra arteries,

430 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

and empty into the splenic nodes, situated around the hilum
of the spleen; (3) a set which drains the greater curvature and
ends in the right gastroepiploic nodes, the efferents of which
pass to the subpyloric nodes; (4) those draining the pylorus
empty into the hepatic and subpyloric nodes.

SMALL INTESTINE

The Duodenum

The duodenum is about 10 inches long, and runs in a curved
direction from the pylorus to the jejunum, which it joins on
the left side of the second lumbar vertebra. The concavity
of the curve looks toward the left and embraces the head of
the pancreas. It is divided, for description, into four parts
or portions.

The first portion of the duodenum is almost completely sur-
rounded by peritoneum, derived from the two layers of the
lesser omentum, except a small space, posteriorly, near the
neck of the gall-bladder and the vena cava. The second portion
is covered by peritoneum anteriorly, except where it is in rela-
tion with the transverse colon. The third portion is covered
by peritoneum anteriorly, except where the superior mesenteric
vessels cross, about its middle aspect. The fourth portion is
fixed by peritoneum to the abdominal wall, which covers it
anteriorly.

The first portion extends from the pylorus to the neck of
the gall-bladder. Its length varies in different subjects, and
its direction changes with the degree of distention of the
stomach. :

The second portion extends from the neck of the gall-bladder
down along the right side of the vertebral column, usually
to the body of the fourth lumbar vertebra. It is 3 or 4 inches
long.

The third portion begins where the second ends and passes
from right to left over the great vessels and crura of the dia-
phragm in front of the third or fourth lumbar vertebra. It
is 2 or 3 inches long.

The fourth portion ascends along the left side of the vertebree
and aorta upon the left crus of the diaphragm and ends at the

Se ee UPC
4

THE DUODENUM 431

left side of the second lumbar vertebra. It is about 2 inches
long. ‘This portion ends in the duodenojejunal flexure, being
held in position by the peritoneum, and the duodenojejunal
flexure is further bound down by the suspensory muscle of the
duodenum or the suspensory ligament of Treitz. This con-
sists of a few non-striated muscle fibers fused with connective
tissue. It arises from around the celiac axis and left crus,
to be inserted into the duodenojejunal flexure, and a portion
of the ascending portion of the duodenum.

The Relations of the Duodenum.—The first or superior portion
has above and in front the gall-bladder, the quadrate lobe
of the liver; behind is the gastroduodenal artery, the common
bile duct, the portal vein; below is the head of the pancreas.
It helps to form the lower boundary of the foramen of Winslow.

The second or descending portion is crossed by the transverse
colon, which is attached to it by connective tissue; above
and in front is the right lobe of the liver; behind is the inner
part of right kidney, the renal vessels, and the inferior vena

cava; to the inner side is the common bile duct and the head

of the pancreas; outerside is the hepatic flexure of colon.
The transverse colon divides the duodénum in this portion,
into a supracolic and infracolic region.

The third portion is crossed in front by the superior mesenteric
vessels and the mesentery; behind it rests on the inferior vena
cava, the aorta, and crura of the diaphragm. Above is the
head of the pancreas.

The fourth or ascending portion has behind the aorta, the
left renal vessels, the left psoas muscle; to the right is superior
mesenteric vessels and the uncinate process of the head of the
pancreas; to the left and posterior are the duodenojejunal
folds and fossze.

The arteries are the pyloric, the superior pancreaticoduodenal
from the hepatic, and gastroduodenal respectively; the inferior
pancreaticoduodenal, a branch of the superior mesenteric.
The veins correspond to the arteries. The superior pancreatico-
duodenal opens into the gastroduodenal, the inferior pan-
creaticoduodenal into the superior mesenteric vein. The nerves
are derived from the solar plexus. The lymphatics empty
into the celiac nodes of the preaortic group.

/ = ~ i ‘

432 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

The Jejunum and Ileum

The jejunum includes the first two-fifths of the remaining
part of the small intestine, running from the left side of the
first or second lumbar vertebra to the beginning of the ileum,
and occupying the umbilical and left lumbar and iliac regions.
_ Its coats are thicker and more vascular, and is of a deeper
color and larger caliber than the ileum.

The arteries supplying the jejunum are derived from the
superior mesenteric and are called the arteria intestine tenuis.
They are arranged in loops between the mesentery; single
loops near the beginning, then double and even tertiary loops
are seen as the ilium is approached. The veins correspond
to the arteries and empty into the superior mesenteric vein,
which unites with the splenic to form the portal. There are
no valves in the mesenteric veins.

The nerves are derived from the celiac axis (sympathetic)
and some from the vagus. The plexus of Auerbach is found
in the muscular coat, and Meissner’s plexus is situated in the
submucous coat, and is made up from filaments of the celiac
plexus and vagus. The lymphatics pass to the mesenteric
nodes, between the layers of the mesentery.

The remainder of the small intestine is the zlewm, which
ends by opening into the inner side of the commencement
of the large gut in the right iliac fossa. Its coils oceupy the
hypogastric, umbilical, and right lumbar and iliac regions.

THE LARGE INTESTINE

The large intestine is that part of the alimentary canal
which extends from the end of the ileum to the anus; it is
about 53 feet long. It commences by a dilated part, the cecwm,
in the right iliac fossa, ascends to the under surface of the
liver, then runs transversely across the abdomen to the vicinity
of the spleen, descends to the left iliac fossa, and forms the
sigmoid flexure, and finally passes along back of the pelvis
to end at the anus.

The cecum is the large cul-de-sac which is the beginning of |
the large intestine, and is about 3 inches broad and 2% inches :
long. It is variously situated, being found on the psoas, external

Sie. 5 F
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4

THE LARGE INTESTINE 433

to it, on the iliacus, internal to it, on the pelvic brim, or entirely
within the pelvis. In any of these positions it is entirely sur-
rounded by peritoneum.

The vermiform appendix comes off from the inner and back
part of the cecum, near its lower end, and extends upward
and inward behind it. This is a piece of gut of the diameter
of a goose-quill, varying from 3 to 6 inches in length, curved
upon itself, and ending in a blind extremity. It tapers gradually
to its end, which is blunt, is completely invested by the peri-
toneum, which forms for it a mesentery (mesoappendix), and
at its connection with the cecum is guarded by an imperfect
valve (valve of Gerlach). This is not always constant.

The ileocecal valve guards the opening of the small intestine
into the large gut. This junction is oblique and situated about
25 inches above the lower extremity of the cecum. It is a
double fold lying transversely to the long axis of the colon.
Each fold of the valve is made up of the mucous and submucous
coats, reinforced by some circular fibers from the muscular
coat, of each portion of the gut, and is covered on the side
toward the ileum with villi. At each end of the opening these
folds run together and are prolonged some distance around
the gut, forming the retinacula.

The ascending colon runs from the cecum, above the ileo-
cecal valve, upward to the under surface of the liver on the
right side of the gall-bladder, and then turns forward and
to the left to form the hepatic flexure. The peritoneum rarely
forms for it a mesocolon; generally it covers only the front
part and the sides. It occupies the right lumbar and hypo-
chondriae regions.

The transverse colon arches across the abdomen, the con-
vexity looking toward the belly wall, and makes a sudden
turn backward and downward beneath the spleen, forming
the splenic flexure, and is completely invested by the peri-
toneum, which holds it to the anterior aspect of the pancreas
and second portion of the duodenum; by two layers of peri-
toneum called the transverse mesocolon, the upper surface of
which fuses with the posterior layer of the great omentum.
It oceupies the right hypochondriac, upper part of umbilical,
and left hypochondriae regions. At the splenic flexure is
attached the phrenocolic ligament, a fold of peritoneum extending
to the diaphragm opposite the tenth or eleventh rib.

28

434 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

The descending colon descends from the splenic flexure, to
end at the left iliac fossa in the sigmoid flexure. It is covered
in front and laterally by the peritoneum. It occupies the
left hypochondriac and lumbar regions. .

The Relations of the Cecum.—It lies in the right iliac fossa,
resting on the ileopsoas muscle, immediately behind the abdom-
inal wall. The appendix, the first lumbar nerve, the genito-
crural, and external cutaneous branches of the lumbar plexus
are in relation with it behind. Internal at the brim of the
pelvis are the external iliac vessels and the ureter, as it crosses
the bifurcation of the common iliac.

The arteries of the cecum are: The anterior and posterior
cecal arteries, branches of the iliocolic. They are given off
at the ileocecal junction. The veins are the same as the arteries
and open into the superior mesenteric vein through the ileo-
colic. They are radicles of the portal system. The nerves
are derived from the sympathetic system, through the superior
mesenteric plexus. The lymphatics drain into the superior

mesenteric nodes through the channels of the ileocecal nodes.
' The Relations of the Ascending Colon.—In front, the coils of
the ileum and abdominal wall; behind, the quadratus lumborum
muscle, the lower thoracic intercostal nerves, the anterior
and lower surface of the right kidney; above, the hepatic
flexure of the colon rests against the inferior surface of the
right lobe of the liver in the impressiocolica and the gall-bladder.
Internally, the second portion of the duodenum touches the
hepatic flexure.

The Relations of the Transverse Colon.—It describes an arch
with its concavity directed backward and upward to the verte-
bral column. Above, it is in touch with the liver and gall-
bladder, the greater curvature of the stomach, the lower end
of the spleen; below with the small intestines; by its anterior
surface with the layers of the great omentum and the abdominal

wall; posteriorly it rests, the right side, on the second portion

of the duodenum and head of the pancreas, and on the left
side is in relation with coils of the jejunum and ileum.

The splenic flexure is in relation with the posteroinferior surface
of the stomach, the tail of the pancreas, and the diaphragm

opposite the tenth and eleventh ribs. The phrenocolic liga- -

ment attaches it to the diaphragm.

a a

THE LARGE INTESTINE 435

The Relations of the Descending Colon.—Passes to the iliac
fossa, to the left of the left kidney and psoas muscle; in front
are the coils of the jejunum and ileum; behind, is the quadratus
lumborum muscle and the twelfth thoracic nerve.

The sigmoid flexure ends in the rectum. From the end of
the descending colon it forms an S-shaped curve, ending oppo-
site the left sacroiliac joint. In front of it are the belly wall
and some coils of small intestine. The peritoneum forms a
loose mesocolon for it. It is the narrowest part of the colon.

The Relations of the Sigmoid Flexure of the Colon.—Anteriorly,
it is covered by the coils of the jejunum and ileum; behind,
in the iliac fossa, it passes over the psoas, and iliacus, muscles,
the branches of the lumbar nerves, except the obturator, the
ureter, the spermatic artery and vein. At the brim of the
pelvis it curves over the internal and external iliac vessels,
and behind and below, are the left common iliac artery and
vein.

The rectum is the lowest part of the large intestine, and
extends from the sigmoid flexure to the anus. It has been
divided into three parts: The first part extends from the
left sacroiliac joint to the centre of the third piece of the sacrum;
the second part, to the tip of the coccyx; and the third part,
to the anus.

The rectum is about 8 inches long and somewhat cylindrical
in form, narrower above than the sigmoid flexure, but it en-
larges as it descends, and just above the anus is remarkably
dilated, forming the ampulla. The first part has a mesorectum;
the second part is covered by peritoneum in front and laterally;
the third part has no peritoneal covering.

The Relations of the Rectum.—Behind, the upper part of the
rectum is in relation with the superior hemorrhoidal vessels,
the left pyriformis muscle, and left half of the sacral plexus
of nerves, which lie between it and the sacrum; its lower part
rests on the sacrum, coccyx, and levatores ani muscle, a dense
fascia intervening; in front, it is in relation with the posterior
surface of the bladder, in the male, and the posterior aspect
of the uterus and its left appendages, the coils of the intestines
intervening. The extremity of the rectum is in relation in
front with the triangular portion of the bladder, the seminal
vesicles, the vas deferens, and more anteriorly with the prostate
in the male; in the female, with the posterior wall of the vagina.

436 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

The cul-de-sac of Douglas (rectovaginal pouch) is the space in
front of the rectum and behind the cervix and upper fourth
of the vagina. It is formed by the peritoneum reflected over
the rectum to the vagina and uterus. In the male it is the
space formed between the rectum and bladder, and is called
the, rectovesical space, or pouch.

The Arteries to the Colon.—The ascending colon by the right
colic; the hepatic flexure, by the branches of the anastomosing
loop formed by the right and middle colic; the transverse colon,
by the branches of the anastomosing right, middle, and left
colic arteries; the splenic flexure, by the branches derived
from the anastomosing loop of the middle and left colic; the
descending colon is supplied by branches from the left colic;
the sigmoid flexure, by the sigmoid artery. The right and
middle colic arteries are derived from the superior mesenteric,
the left and sigmoid branches are from the inferior mesenteric
artery. The arteries to the rectum are the superior hemor-
rhoidal, a branch of the inferior mesenteric; the middle hemor-
rhoidal, a branch of the anterior division of the internal iliac,
and the inferior hemorrhoidal, from the internal pudie.

The veins of the large intestines correspond to the arteries
and open into the portal vein, through the superior and inferior
mesenteric veins; the former joins with the splenic to form
the portal, the latter opens into the splenic vein. Veins of the
rectum drain, into the inferior mesenteric, by the superior
hemorrhoidal vein, the middle hemorrhoidal, into the internal
iliac, and the inferior hemorrhoidal into the internal pudie.
These veins form the hemorrhoidal plexus, which communi-
cates with the portal and systemic circulations, the former
by means of the inferior mesenteric, receiving the superior
hemorrhoidal, and the latter the middle and inferior hemor-
rhoidal opening into the internal iliac, and internal pudie
veins respectively.

The lymphatics of the cecum, ascending and _ transverse
colon drain into the mesenteric nodes; the descending colon
and sigmoid flexure into the lumbar nodes. The rectal and
anal lymphatics drain into the preaortic nodes. The skin
around the margin of the anus is drained by the radicles which
pass into the superficial inguinal nodes.

The nerves of the large bowel and rectum are derived from
the sympathetic system, the former through the superior

a i i ee

ee ee eT en Fee

THE LIVER 437

mesenteric and inferior mesenteric plexuses, the latter through
the superior hemorrhoidal and the pelvic plexuses. The spinal
centres for the nerves of the anus and rectum are situated in
the first and second sacral segments of the spinal cord. (Gray.)

THE LIVER (HEPAR)

The liver is the largest gland of the body, and fills the entire |
hypochondrium, the greater portion of the epigastrium, some-
times extending into the left hypochondrium. It weighs from
50 to 60 ounces in the male; 40 to 50 ounces in the female.
Constitutes one-eighteenth of the body weight in the adult, and
one thirty-sixth of body weight in the fetus. It measures,
transversely, from 8 to 9 inches; anteroposterior, 4 to 5 inches,
and vertically, near its right surface, about 6 or 7 inches.
Its specific gravity is 1.05.

The liver presents a superior surface, which includes the right
and left lobes; an inferior surface, including the right, left,
caudate, Spigelian, and quadrate lobes: anterior and posterior
surfaces, comprising the right and left ‘lobes ; a lateral surface
of the right lobe only.

It has an inferior border, or margin, which is thin and sharp,
and notched opposite the falciform ligament, for the round

-ligament (umbilical notch), and opposite the cartilage of the

ninth rib by a second notch for the fundus of the gall-bladder.

The left extremity of the inferior margin of the liver is thin
and flattened from above downward.

The ligaments of the liver are all peritoneal folds excepting
the round ligament, which is a fetal remnant of the umbilical
vein. The falciform ligament (ligamentum falciforme hepatis)
is broad and thin, runs from before backward, and is attached
above to the diaphragm and the posterior surface of the sheath
of the right rectus muscle as far as the umbilicus; below to
the superior surface of the liver, from the posterior border
to the notch in the anterior border. The free anterior border
has between its layers the round ligament. It runs along the
longitudinal fissure from the umbilicus to the vena cava.
The lateral ligaments are peritoneal folds which extend between
the diaphragm and the corresponding borders of the liver,
the left being to the left of the esophageal opening. - The
coronary ligament is a process of peritoneum which is reflected

438 SPLANCHNOLOGY, OR ANATOMY OF THRE VISCERA

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THE LIVER 439

to the posterior surface of the liver in the situation of its appo-

‘sition with the diaphragm. It is continuous with the lateral

ligaments on each side and with the suspensory in front.

The fissures of the liver are five. The longitudinal separates
the right and left lobes. It is joined by the transverse fissure,
or fossa, the part in front of that point being called the wmbilical
fissure, and lodging the umbilical vein or its remains, the round
ligament. The fissure of the ductus venosus is the part of the
longitudinal fissure behind the transverse. It lodges the
ductus venosus or its remains. The transverse or fossa or
portal fissure is the point of exit and entrance of the vessels,
nerves, and ducts. It lies between the quadrate and Spigelian
lobes. The fissure for the gall-bladder is on the under surface
of the right lobe, parallel to the longitudinal fissure, separated
from it by the quadrate lobe. The fissure for the inferior vena
cava, sometimes a complete canal, lies to the right of the
Spigelian lobule.

The lobes of the liver are also five in number. The right is
the largest, being six times as large as the left, and is separated
from the left by the suspensory ligament and longitudinal
fissure respectively, and in front by the interlobar notch.
Its under surface is marked by the transverse fissure and that
of the gall-bladder, and its posterior surface by that of the
inferior vena cava, and anteriorly is the impressio colica for
the hepatic flexure, behind another, the impressio renalis,
for the right kidney, and just to the right of the neck of the
gall-bladder, the impressio duodenalis. The left lobe is flattened,
lies in the epigastrium, and is in relation below with the stomach.
The lobus quadratus is on the under surface of the right lobe,
and is bounded in front by the free surface of the liver, behind
by the transverse fissure, on the right by the fissure for the
gall-bladder, on the left by the umbilical fissure. The Spigelian
lobe lies behind and above the preceding, and is bounded in
front by the transverse fissure, on the right by the fissure
of the vena cava, and on the left by the fissure for the ductus
venosus. The caudate lobe, or tuberculum caudatum, runs
outward from the base of the Spigelian lobe to the under surface
of the right lobe, lying between the transverse fissure and that
for the inferior vena cava.

The Structure of the Liver.—It is covered by a serous layer
derived from the peritoneum, except the posterior surface

440 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

for about 3 inches, included between the reflections of the
coronary ligaments. Beneath this serous covering is a fibrous’
or areolar capsule (capsule of Glisson), which passes into the
transverse fissure around the vessels and blends with the
areolar tissue which holds the liver lobules together.

The vessels of the liver are:

The hepatic artery and portal vein, with nerves and lymphatics,
pass to, and the hepatic ducts pass out from, the transverse
‘fissure. These are all situated between the layers of the lesser
omentum, lying in the following relative position: The duct
to the right, the artery to the left, and the vein between them
and on a posterior plane. They are all enclosed in some loose
areolar tissue. The hepatic artery is derived from the celiac
axis, and divides into a right and left branch. Entering the
transverse fissure they pass between the lobules (interlobular
branches), and give off small twigs which pass into the
lobules and end in the capillary plexus between the cells.

The portal vein divides into interlobular veins, then form
a plexus, which gives off intralobular capillaries, ramifying
around and in the cells. Thus bringing the blood directly
in relation with the cells to form the bile. The hepatic veins
are three large trunks, opening into the inferior vena cava.
The ducts start as minute passages between the cells (biliary
passages, bile capillaries), then radiating to the circumference
of the lobules empty into small interlobular ducts. ‘These
pass into the portal canals and form two large ducts, a right
and left, which accompany the hepatic arteries and portal
vein to the transverse fissure of the liver, to become the single
hepatic duct. The nerves of the liver are derived from the
left vagus and sympathetic system. |

The lymphatics end in the celiac group, some to the hepatic
nodes at the transverse fissure, and the efferents from the
nodes beneath the capsule of Glisson, pieree the diaphragm
to empty into the nodes about the inferior cava. A few pass
to the nodes about the abdominal portion of the esophagus.,

THE GALL-BLADDER

This is a pear-shaped sac lying in the impression of the
right lobe, from the right end of the transverse fissure to the
anterior free margin. It is 4 inches long and 13 inches broad,

7

LS rl lh e,llU eee. lh

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THE PANCREAS 441

holding 8 to 12 drams, and is held in place by areolar tissue
and the peritoneum. ‘The fundus looks downward, forward,
and to the right; the body and neck upward, backward, and
to the left. Its relations are as follows: Above, liver; below,
ascending duodenum, pyloric end of stomach, hepatic flexure
of colon; in front, abdominal wall (ninth or tenth costal cartil-
ages). The hepatic duct is formed by the junction at an obtuse
angle of a branch from each lobe, and runs downward and to
the right for nearly 2 inches, and joins the eystie duct to form
the common bile duct. The cystic duct is 13 inches long, and
descends toward the left and joins the above as described.
The common bile duct is nearly 3 inches long and 3 lines in
diameter. It runs along the right border of the lesser omentum
behind the first part of the duodenum, and between the pan-
creas and descending duodenum, then to the right of the
pancreatic duct, with which it opens by a common orifice
(ampulla of Vater) at the summit of.a papilla just below the
middle of the inner wall of the second portion of the duodenum.
The eystic artery and vein comprise the blood supply.

THE PANCREAS

The pancreas is a compound racemose gland, of a reddish-
white color. Situated at the back of the epigastrium and left
hypochondrium; connected to the posterior abdominal wall
by connected tissue and lies retroperitoneal. It is 5 to 6 inches
long; its breadth is 13 inches; its thickness 4 to 1 inch, being
greater at its right extremity and upper border. The pancreas
is divided into a head, a neck, a body, and a tail.

The Relations of the Pancreas.—The head is flattened from
before backward, and is lodged within the curve of the duo-
denum. Above, is the first portion of the duodenum and the
gastroduodenal artery and vein; below, it overlaps the third
portion of the duodenum; in front, in the groove between
the right lateral and lower borders, are the anastomosing pan-
creaticoduodenal arteries, the transverse colon and _ inferior
layer of the transverse mesocolon, and coils of intestines.
The uncinate process has passing over it the superior mesenteric
vessels, the vein lying to the right of the artery. Behind,
is the inferior vena cava, the renal vein and artery, the right

442 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

crus of the diaphragm, the vena azygos major vein, the thoracie
duct, and the junction of the splenic and superior mesenteric
veins to form the portal vein, near the upper border. To the
right is the second portion of the duodenum, which it over-
laps, and the common bile duct; to the left it passes behind
the fourth portion of the duodenum.

The neck is about 1 inch long, flattened from before back-
ward. Its anterosuperior border is in relation with the pylorus;
the posteroinferior surface, the commencement of the portal
vein.

Fia. 71

The pancreas and its relations. (Gray.)

The Body.—In front the anterior surface is in relation with
the posterior inferior surface of the stomach, the lesser peri-
toneal sac intervening. The posterior surface is devoid of
peritoneum, and rests on the aorta, the left kidney and its
vessels, suprarenal gland, splenic vein, near its upper border,
the crura of the diaphragm, and the origin of the superior
mesenteric artery, the inferior mesenteric vein, as it passes
up to open into the splenic vein. Below the inferior surface
is the duodenojejunal fold, and to the left the splenic flexure
of the colon. The superior border is in relation with the celiac
axis, its hepatic branch to the right, and splenic artery on the

r

ee a er ee a ee
\

THE KIDNEYS 443

left side. The inferior border has emerging beneath it from
above downward the superior mesenteric vessels; from below
upward the inferior mesenteric vein. The anterior border
gives attachment to the transverse mesocolon.

The tail is in relation with the spleen and the splenic flexure
of the colon.

The duct of the pancreas is called the pancreatic duct, or
canal of Wirsung. It extends transversely through the sub-
stance of the gland to drain the lobules by means of small
ducts, which open into it. Increasing in size it reaches the
neck, passes downward, backward, and obliquely to the right,
piercing the muscular and mucous coat of the second portion
of the duodenum where it opens into the ampulla of Vater,
common to it and the bile duct; the latter opens into the canal
of the duodenum. 7
' The arteries of the pancreas are the superior pancreatico-
duodenal, a branch of the gastroduodenal; the inferior pan--
creaticoduodenal, a branch of the superior mesenteric; small
and large panereatic arteries, branches of the splenic. The
veins are: The inferior pancreaticoduodenal, opening into the
superior mesenteric and superior pancreaticoduodenal draining
into the gastroduodenal vein, and the pancreatic veins draining
the body and tail pass to the splenic. The nerves are derived
from the celiac, superior mesenteric, and splenic plexuses. The
lymphatics empty into the splenic, preaortic (Sappey), superior
mesenteric, and pancreaticoduodenal nodes.

The pancreas lies in front of the second lumbar vertebra.
When the stomach and colon are empty it can be felt about
3 inches above the umbilicus.

THE URINARY ORGANS

The urinary organs include the kidneys, which secrete the
urine; the ureters convey it to the bladder, where it is retained
until voided; then the urethra, which discharges it from the
body.

THE KIDNEYS (RENES)

The kidneys are situated on each side of the vertebral column,
resting on the psoas magnus and the quadratus lumborum

444 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

muscles. They are retroperitoneal and correspond to the
space included between the upper level of the twelfth thoracic

Fie. 72

HEPATIC
VEINS

ee

INFERIOR PHRENIC
ARTERIES

CESOPHAGUS

Mi
\"

SUPERIOR
MESENTERIC—
ARTERY

CELIAC
ARTERY

INFERIOR
MESENTERIC
ARTERY

COMMON INTERNAL
ILIAC ARTERY SPERMATIC
AND VEIN ARTERY
AND VEIN
INTERNAL

ILIAC ARTERY
AND URETER

Posterior abdominal wall, after removal of the peritoneum, showing kidneys,
suprarenal capsules, and great vessels. (Corning.)

THE KIDNEYS 445

above, and opposite the third lumbar vertebra below. The
right kidney is lower than the left. In the female they are a
little lower than in the male.

Each is bean-shaped, measures about 4 to 43 inches in length,
2} in breadth, and 1 to 13 inches in thickness, and weighs
about 4 to 6 ounces. They lie in the right and left hypochon-
drium, the epigastrium, and the right and left lumbar regions.

The anterior surface of the kidney is convex and looks forward
and somewhat outward.

The posterior surface is flatter than the anterior and is em-
bedded in fatty areolar tissue.

The external border is convex, directed outward and back-
ward.

The internal border is concave, directed forward and a little
downward, and presents a deep longitudinal fissure, the hilum,
for the passage of vessels and nerves.

The superior extremity is directed upward and slightly inward,
is thick and rounded, supporting the suprarenal capsule.

The inferior extremity is directed downward and slightly
outward. It is smaller and thinner than the upper, and extends
down to within about two inches of the iliac crest.

The relations of the right kidney are in front, about three-
fourths of its surface rests in the impressio renalis of the inferior
surface of the right lobe of the liver; internally with the second
portion of the duodenum; the lower part is covered by the
ascending colon; the small intestines are also in relation. Behind
it rests on the psoas, the quadratus lumborum, the transversalis
muscles, the crus of the diaphragm, the anterior layer of the
lumbar aponeurosis, the internal and external arcuate liga-
ments, the lumbocostal ligaments, the last thoracic and first
lumbar nerves. The twelfth rib makes an impression in the
right kidney. Externally, its outer border rests on the abdom-
inal wall. Internally, the renal vessels and ureter, and the
inferior vena cava. Above, it is capped by the suprarenal
gland. Below, it extends to within 2 inches of the crest of
the ilium. The left kidney, in front, is covered along the upper
part by the suprarenal gland, the renal impression of the spleen
near its outer border, the body of the pancreas overlies its
middle area, and between the splenic and pancreatic relation
is a small space in contact with the posteroinferior surface
of the stomach, also the descending colon and the intestines

446 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

touch it. The lesser peritoneal sac extends over the left kidney
and suprarenal. The external border is in relation with the
spleen above. ‘The posterior, internal, superior relations
are the same as the right kidney, except that posteriorly it

Fig. 73

COLUMN OF
BERTIN .

_.MEDULLARY
PYRAMID ~

MEDULLARY
PYRAMID
COLUMN OF
BERTIN

URETER

Vertical section of kidney, showing the secreting portion, the vessels, and the
beginnings of the ureter. (Testut.)

is grooved by the eleventh and twelfth ribs. The areas in
relation with the liver, the spleen, and intestines are covered
by peritoneum.

Fixation of the Kidney.—The kidney is embedded in a mass
of fatty tissue (capsule adiposa) surrounded by a fibrous sheath

ee ef ee ee ee et eer we

THE URETERS 447

named the fascia renalis, continuous with the subperitoneal
fascia. Its anterior -portion passes inward over the renal
vessels, and blends with the same layer from the opposite
side. Its posterior layer passes behind and fuses with the
fascia over the quadratus lumborum and psoas muscles; passing
to the vertebral column. At the upper extremity the two
layers fuse with the fascia of the diaphragm.: Below they
remain separate and are lost on the subperitoneal fascia of
the iliac fossa. The fascia renalis is attached to the kidney
capsule by numerous trabecule. Behind the fascia renalis
is the pararenal fat, or body. The kidney is held also by the
attachments to adjoining viscera, by the means of peritoneal
folds or ligaments, as the lienorenal ligament.

The renal arteries divide into three or four branches before
entering the hilum. They give off a branch to the suprarenal
gland, the ureter, and surrounding muscles. The arteries
lie behind the vein and in front of the ureter. The left renal
vein receives the left phrenic and spermatic veins and opens
into the inferior vena cava.

The nerves of the kidney are derived from the sympathetic
through the renal plexus.

The lymphatics’ drain from three locations: From the
perirenal fat, which drains directly into the upper lateral
aortic nodes; from beneath the capsule, which joins at the
hilum with the third set, from the substance of the kidney, and
pass along the renal vessels to empty into the lateral aortic
nodes. The subcapsular and perirenal lymphatics communicate
freely with each other.

THE URETERS

The ureters are two in number and convey the urine from
the kidney to the bladder. The urine is collected from several
minor calices, ten to twenty in number, which open into the
major calices, the latter by their junction form the pelvis,
or dilated portion of the ureter. It is on a line with the first
lumbar vertebra.

The ureter proper is divided into an abdominal portion (pars
abdominalis) and a pelvic portion (pars pelvina). They are
10 to 12 inches in length and § of an inch in diameter. The

448 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

walls are from 1 to 2 mm. thick. It has 4 main constrictions:
(1) At the junction with its pelvis; (2)-as it passes over the
brim of the pelvis; (3) as it enters the bladder; (4) at its termi-
nation.

Relations of the Right Ureter (Abdominal Portion).—It is retro-
peritoneal, and lies on the psoas magnus muscle and crosses
the genitocrural nerve. The spermatic artery or ovarian
passes over it from within outward; the spermatic vein from
without inward. At its origin it lies behind the second portion
of the duodenum, the right colic vessels, and near the brim
of the pelvis, the end of the ileum. It crosses the common
iliac artery at its bifurcation into the internal and external
iliac at the brim of the pelvis.

The Pelvic Portion.—It lies on the lateral wall of the pelvis,
behind the peritoneum; in front of the internal iliac vessels;
passing downward and forward it enters the bladder, piercing
the wall and within which it runs for about ~ of an inch to
terminate in a slit-like aperture into the cavity of the bladder.
When the bladder is distended, the ureters are two inches apart;
when empty, about one inch nearer each other. It is crossed
in front by the vas deferens, in the male, which passes down-
ward, backward, and inward on a level with the upper margin
of the seminal vesicle. In the female it lies behind the ovarian
fossa, forming its posterior boundary. ~ Passes forward and
inward, on a line with the cervix of the uterus, lying { of an
inch external. It is accompanied for about 1 inch by the
uterine artery, a branch of the anterior division of the internal
iliac. The uterine artery crosses above the ureter from with-
out inward to ascend between the two layers of the broad
ligament.

The relations of the left ureter are the same as the right side,
except that the sigmoid flexure of the colon passes over it,
in front, at the lower part of the abdominal portion.

The arteries are derived from the renal, spermatic, internal
iliac, and inferior vesicle. The veins correspond to the arteries.
The nerves are filaments from the inferior mesenteric, sper-
matic, and pelvis plexuses. The lymphatics, upper portion,
drain into the efferent branches from the kidney; the abdominal
portion, into the lateral aortics; near the pelvis, the common
iliac nodes; and within the pelvis, the internal iliac nodes.

THE URINARY BLADDER 449

THE URINARY BLADDER (VESICA URINARIS)

The bladder is situated in the pelvic cavity, but in infancy
and when distended in the adult, extends into the hypogastrium.
It measures when moderately distended 5 to 54 inches in
length, 43 in width, and 3 inches from before backward. It
holds a pint of urine without discomfort. The bladder presents
a superior, anteroinferior, and two lateral surfaces; a base or
fundus, and an apex, or summit.

The interior of the bladder shows the mucous membrane
thrown into ruge, the orifices of the ureters, and the trigone.
The ureteral orifices are about 2 inches apart, when the bladder
is moderately distended. The trigone, or trigonum vesical, is a
smooth, triangular surface, paler than the rest of the mucous
membrane. It is bounded at the basal angles to. the orifices
of the ureters, and the apex to the urethral orifice. The ureteral
folds are the prolongations extending beyond the ureteral
orifices, of the transverse ureteral fold containing muscle
fibers covered by the mucous membrane. The urethral open-
ings are surrounded by a circular fold of mucous membrane,
called the annulus urethralis.

The ligaments of the bladder are true and false. ‘The true
are the two anterior, two lateral, and the urachus. The false
are five, and consist of folds of peritoneum.

The two anterior true or puboprostatic ligaments extend from
back of the pubic bone, one on each side of the symphysis,
to the front of the neck of the bladder, over the anterior
surface of the prostate gland. The two lateral true ligaments
arise from the pelvic wall, being formed by the pelvic fascia,
(rectovesical fascia), and are inserted into the sides of the
base of the bladder and the lateral surfaces of the prostate
gland. The urachus is the impervious remains of the allantois,
an embryological structure, which helped to form the bladder.
It is attached to the apex of the bladder and passes to the
umbilicus, between the transversalis fascia and peritoneum,
forming the plica umbilicalis media. ‘The two posterior false
ligaments are folds of peritoneum, passing from the sides
of the rectum, in the male to the outer and posterior aspect
of the bladder (the rectovesical folds); in the female these
folds are called (the vesicouterine folds) and pass from the

29

450 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

sides of the uterus to the lateral and posterior aspect of the
bladder; they form in the male the lateral boundaries of the
rectovesical pouch; in the female, the lateral boundaries of the
rectovaginal pouch, or cul-de-sac of Douglas. The two lateral false
ligaments and the superior false ligaments are folds of peritoneum
reflected from the walls of the pelvis, on to the obliterated
hypogastric arteries, and the urachus respectively.

The Relations of the Bladder.—The superior surface is covered
by peritoneum and is in relation with the uterus in the female,
the intestines, and sometimes the sigmoid flexure of the colon.
Near its posterior aspect the vas deferens is in contact with
it. When the bladder is relaxed, this surface shows a trans-
verse fold of peritoneum, called the plica vesicalis transversa.
The anteroinferior surface is devoid of peritoneum, when
empty, and lies in relation with the obturator internus muscles,
the puboprostatic ligaments and rectovesical fascia. When
distended the upper part of this surface is covered by peri-
toneum. Between the bladder and the pubes is a triangular
space, containing areolar and adipose tissue, called the pubo-
vesical, or space of Retzius. During distention this space is
increased, and the anterior-inferior surface lies in contact
with the abdominal wall. The lateral surfaces are covered
by peritoneum behind and above, the impervious -hypogastric
arteries, below, and in front of these, the bladder is uncovered

by peritoneum and is separated from the pelvic walls and ©

levatores ani muscles by areola tissue and contained fat. The
vas deferens crosses the ureter and lies between it and the
posterior portion of this surface. When the bladder is empty,
the peritoneum sinks down to the sides of the bladder and
form the paravesical fosse. ‘The fundus is covered by peri-
toneum to within 13 inches of the prostate gland, and forms
the anterior boundary of the rectovesical and vesicouterine
pouches in the male and female respectively. Below the

reflection of peritoneum, the bladder is in relation with the

second portion of the rectum, the seminal vesicles, and the
vasa deferentia. The ureters open into the fundus, about
1} inches above the base of the prostate gland. The neck
is the commencement of the urethra, and is surrounded by
the prostate gland. The apex, when empty, is ‘on a level with
the upper border of the symphysis pubis.

The arteries are derived from the superior, middle, and

—s =. “a

fe < Me .
—

’
.

THE PROSTATE GLAND 451

inferior vesical branches of the anterior division of the internal .
iliac, with additional branches from the uterine and vaginal
in the female. The veins drain into the prostatic plexus around
the neck and sides of the bladder, and then pass to the internal
iliac veins.

The nerves are branches from the pelvic plexus of the sympa-
thetic system, and the third and fourth sacral nerves.

The Lymphatics.—The lymphatics from ‘the anterior surface
pass to the external iliac nodes; the posterior surface to the
internal iliac and hypogastric nodes, and a few nodes at the
promontory of the sacrum.

THE ORGANS OF REPRODUCTION (MALE)

THE PROSTATE GLAND

The prostate gland is immediately in front of the so-called
neck of the bladder and around the commencement of: the
urethra. It rests against the rectum behind, and lies on the
subpubic fascia (posterior layer of triangular ligament). It
resembles a chestnut in form, and measures transversely
1% inches, from base to apex 1% inches, and nearly 1 inch in
thickness, its weight being 6 drams. The base looks toward
the neck of the bladder, its apex touches the deep perineal
fascia (triangular ligament), the posterior surface is joined to—
the rectum by areolar tissue, and its pubic surface, grooved
longitudinally, lies { inch from the pubic symphysis. It is
supported in its position by the puboprostatic ligaments,
posterior layer of the deep perineal fascia, and the front of
each levator ani (the levator prostate).

~The prostate consists of two lateral lobes and a middle
lobe. ‘The lateral lobes are separated behind by a deep notch,
and are continuous in front of the urethra. The middle is
smaller, lying posteriorly between the lateral lobes.

The urethra and common seminal ducts pierce the prostate.
The gland has a dense, firm, fibrous capsule, which is derived
from the rectovesical fascia and the posterior layer of the.
triangular ligament, and it consists of glandular and muscular
tissue in about equal amounts.

452 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA .

THE PENIS

The penis consists of a root, a body, and an extremity, or
glans penis.

The body is made up of three cylindrical masses of erectile
tissue united together, the two upper of which, lying side by
side and called thé corpora cavernosa, form the, chief bulk
of the organ, and the lower, the corpus spongiosum, contains
part of the urethra. —

The root is attached to the pubic rami by the crura, and to
the symphysis by the suspensory ligament.

The body is cylindrical when flaccid, triangular with rounded
border and sides when erect, the upper side being the dorsum.
It is covered by a very thin skin, which is dark in color and
devoid of adipose tissue, being loosely connected to the organ.
This skin folds upon itself in front to form the prepuce, the
under layer of which joins the cervix and becomes very like
a mucous membrane, covering the glans and blending into
the mucous membrane of the urethra at the meatus. Around
the cervix and corona glandis are small glands, the glandule
Tysoni odoriferee.

The glans (see Corpus Spongiosum) is conical and points
anteriorly, its summit presenting a vertical slit, the meatus
urinarius, from the lower part of which a fold of mucous mem-
brane runs back to join the prepuce, and is called the frenuwm
preputiw. The base of the glans projects at its circumference,
forming the corona glandis, behind which is a constriction,
the cervia.

The corpora cavernosa are closely connected for the anterior
three-fourths, being flattened mesially, while behind they
separate, and enlarging at first to form the bulb of the corpus
cavernosum, gradually taper, and under the name of crura
penis are attached to the rami of the pubes and ischium. In
front they form a single blunt extremity, which is joined by
fibrous tissue to the base of the glans. Below them is a groove
for the corpus spongiosum, and above one for the dorsal vein
of the penis.

The fibrous envelope is composed of longitudinal fibers
common to both corpora, and circular fibers which are internal
and belong to one corpus only. Mesially, where the circular

4 rer Jom

THE MALE URETHRA 453

fibers of both sides meet, they unite to form a septum. This
septum is thick and complete behind, but in front many vertical
slits allow of communication between the two bodies, and have
given to the septum the name septum pectiniforme. From the
inner surface of this envelope numerous fibrous trabecule
pass in all directions. These trabeculz support and enclose
the arterial branches, which form a capillary network opening
directly into the cavernous spaces, some of them forming
convoluted vessels, the helicine arteries, which project into
the trabecular spaces. ‘The blood is returned by the dorsal
vein, prostatic plexus, and pudendal veins.

The corpus spon giosum commences behind, between the
two crura, and in front of the deep perineal fascia, as the
bulb, and in front expands to form the glans. The bulb receives
an investment from the anterior layer of the deep perineal
fascia and is surrounded by the accelerator urine muscles.
The urethra runs through the upper part of the corpus spongio-
sum, surrounded by a layer of erectile tissue, the part within
the bulb being called the bulbous portion of the urethra. The
fibrous envelope is white, thinner than that of the corpora
cavernosa, and encloses a similar trabecular structure. Just
beneath it, forming part of the outer coat, is a layer of muscular
fibers, and a second muscular layer lies beneath the urethral
mucous membrane.

THE MALE URETHRA

The male urethra extends from the neck of the bladder to
the end of the penis, is about 83 inches long, and is lined through-
out by mucous membrane supported by a submucous tissue
and connected by it with the subjacent tissues in its three
parts, viz., the prostatic, membranous, and spongy. Part
of the submucous tissue is composed of a longitudinal muscular —
layer internally and a circular externally.

The prostatic portion is the widest part of the canal, and
traverses the prostate gland, being about 1% inches long,
widest at the middle, and lying above the middle lobe. It
is very dilatable. On its floor is a slight longitudinal elevation
at the back part, which passes back to the uvula vesice, and
is placed in the median line, measuring { inch long and about
s inch at its maximum height. This ridge has been variously

454 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

named the crista urethre, colliculus seminalis, verumontanum,
and caput gallinaginis. On each side of it is a groove, the
prostatic sinus, the floor of which presents the orifices of the
numerous prostatic ducts.

In the forepart of the verumontanum is a depression, which ~
leads into the sinus pocularis, or uterus masculinus, upon or
within the margins of which are the orifices of the ejaculatory
ducts. This sinus forms a cul-de-sac running in the verumon-
tanum and beneath the middle lobe of the prostate.

The membranous portion lies between the apex of the prostate
and the bulb of the corpus spongiosum, and is the narrowest
part of the canal. It is # inch long. It pierces, lies between,
and is invested by the anterior and posterior layers of the

deep perineal fascia, and is surrounded by the compressor
~ urethra, one of Cowper’s glands lying on each side.

The spongy portion of the urethra is enclosed by the corpus
spongiosum, and is about 63 inches long. The bulbous portion,
or sinus, is dilated, but beyond the bulb the urethra is of
uniform caliber as far as the glans, in which it is again dilated,
forming here the fossa navicularis, and its long axis becomes
vertical instead of transverse. At the meatus it is much con-
tracted.

The mucous membrane presents the orifices of many small
racemose glands (glands of Littre) and of many lacune. One
of these latter, in the upper part of the fossa navicularis, is
considerably dilated, and is called the lacuna magna.

Cowper’s glands are yellowish, lobulated bodies, of the size
of a pea, lying between the two layers of the deep perineal
fascia, behind the membranous urethra, and between the
arteries of the bulb above and the transverse fibers of the
compressor urethree below. The lobules are made up of acini
and joined together by fibrous tissue. The ducts from the
‘lobules unite outside the gland into a common duct, which
runs forward beneath the mucous membrane for about an
inch and opens on the floor of the bulbous portion of the
urethra.

THE SCROTUM

The scrotum is a pocket which contains the testicles and
part of the spermatic cords, and is marked superficially by

ae, “aS ee ciate 7 = ll a Rl iat eT are

ee SS

a

THE TESTICLE AND EPIDIDYMIS 455

a median ridge, the raphé, which runs from the penis along
the scrotum and perineum to the anus. The scrotum con-
sists of a layer of skin and the dartos. :

The skin is thin and dark, and presents folds or rug, is
covered with hairs thinly scattered, and is furnished with
sebaceous glands.

The dartos is a thin contractile tunic, of a reddish color,
continuous with the superficial fascia of the groin and peri-
neum; it is very vascular, and is composed of loose areolar
tissue and unstriped muscle. It sends in a partition, the septum
scroti, which separates the two testes, and is attached to the
under surface of the penis and to the raphe.

The testicle is covered from without inward by the following
structures: The scrotum, composed of skin and dartos; the
intercolumnar or external spermatic fascia; cremasteric fascia;
infundibuliform fascia, or internal spermatic fascia; tunica
vaginalis.

The intercolumnar fascia, separated by loose areolar tissue
from the dartos, is attached to and descends from the margins
of the pillars of the external ring.

The cremasteric fascia consists of scattered muscular loops
or bundles (cremaster muscle), connected together by areolar
tissue, the former being continuous with the lower border of
the internal oblique.

The infundibuliform fascia is continuous above with the
fascia transversalis and the subserous areolar tissue of the
peritoneum, These two together, the latter being underneath,
form the fascia propria. It invests the surface of the cord and
sends in septa between its component parts.

The tunica vaginalis (see Testicle proper).

THE TESTICLE AND EPIDIDYMIS

Each testicle is ovoid, flattened from side to side, and sus-
pended obliquely (the left being somewhat the lower), its
upper end being directed forward, outward, and upward,
the lower in the opposite direction. Each is 14 inches long,
1+ inches wide, and less than 1 inch thick, and weighs 3 to 1
ounce.

The front, sides, and both ends of the testis are free, smooth,

456 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

and covered by the tunica vaginalis. At the posterior border
the vessels and nerves enter and emerge, and to this border

as well is attached the epididymis.

The epididymis is a long, narrow structure, made up of a

body, a head, or globus major, and a tail, or globus minor.

Fria. 74

Hernia. The relations of the femoral and internal abdominal rings, seen from
within the abdomen; right side. (Gray.)

The globus major is large, and joined to the upper end of
the testicle by the efferent ducts; the minor is small and pointed,
and is joined to the lower end of the testicle by a reflection
of the tunica vaginalis and some cellular tissue. The convex
surface and anterior border of the epididymis are free and
covered by the tunica vaginalis, as is also the concave or
attached surface (except at the ends), the serous membrane
here forming the digital fossa. On the front of the globus
major are one or more small pedunculated bodies called the
hydatids of Morgagni, believed to be the remains of Miiller’s

rei. wees

THE TESTICLE AND EPIDIDYMIS 457

duct. The epididymis is a convoluted canal whose lumen is
continuous with that of the vas deferens.

The tunica vaginalis is a closed serous sac, and consists of
a visceral layer and a parietal layer.

The visceral layer adheres to the outer surface of the tunica
albuginea, surrounding the testis and epididymis, and joining
them together by a fold. It forms between them the pouch
known as the digital fossa.

The parietal layer is reflected to the inner surface of the
scrotum at the posterior border of the testicle.

The tunica albuginea is the fibrous coat which surrounds
the soft substance of the testis and is reflected at the posterior
border into its interior, forming a sort of septum, the corpus
Highmort or mediastinum testis. This septum, wider above
than below, extends from the upper nearly to the lower end
of the gland, and sends off numerous trabeculee which join
the inner surface of the tunica albuginea. These divide the
organ incompletely into lobules. The tunica vasculosa (pia
mater testis) is a vascular plexus supported by areolar tissue
which covers the inner surface of the tunica albuginea and its
trabeculee.

The gland substance consists of seminiferous tubules, which
are contained within the lobules above mentioned, each lobule
containing two or three seminiferous tubules. Each of these
latter is lined by several layers of epithelial cells, from which,
by a process of division (karyokinesis), are finally developed
the spermatozoa.

The lobules are conical, their bases being turned toward
the circumference, their apices toward the mediastinum. In
the latter situation the tubules become straighter, and unite
to form twenty to thirty large ducts, the tuwbulz rectt. These
tubula rectt open into a vascular network, the rete testis, which
lies in the substance of the mediastinum, and from this issue
twelve to twenty vasa efferentia, which pierce the tunica
albuginea and enter the globus major of the epididymis, where
they now become tortuous and form conical masses, the con
vasculosi.

The vas deferens, the continuation of the epididymis, is
the excretory duct of the testicle. From the globus minor
it runs along the inner side of the epididymis and back of the
testis, and in the spermatic cord to the internal ring; here

458 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

it descends, crossing the external iliac vessels, and curving
around the outer side of the deep epigastric artery. It now
passes beneath the peritoneum to the side of the bladder, and
runs downward, backward, and inward to its base, internal to the
ureter and across the obliterated hypogastric artery. At the
base of the bladder it lies between it and the rectum, internal
to the seminal vesicle, the duct of which it joins (close to the
base of the prostate), after having enlarged and again narrowed,
forming with it the. ejaculatory duct. Its length is about
2 feet and its diameter about 3/5 inch. It has an external
areolar coat, a middle muscular coat of two layers, longitudinal
and circular, and an internal mucous coat covered with columnar
epithelium.

The vesiculz seminales, conical in form, the wider end looking
backward, lie between the rectum and the base of the bladder,
and are the reservoirs for the semen. ‘They are 2 inches long
and 4 inch wide. In front they converge, and each joins the
corresponding vas deferens at the base of the prostate to form
the ejaculatory duct. The vesicle is a single tube 4 to 6 inches
long, coiled up and giving off diverticula. It ends behind in
a blind extremity, and is 2 inches long in its natural condition.

Each ejaculatory duct is ~ inch long, and runs, one on each

side, forward and upward within the prostate, between its .

middle and lateral lobes, and along the walls of the sinus
pocularis, close to the opening of which they empty. Each
has an areolar, a muscular, and a mucous coat.

The semen is a whitish fluid composed of liquor seminis,
seminal granules, and spermatozoa. The granules are z55
inch in diameter. The spermatozoa consist of a head, formerly
the nucleus of a spermatoblast, a body, and a tail. The sperma-
toblasts constitute one of the layers of epithelial cells lining
the seminiferous tubules.

The spermatic cord extends from the internal ring to the
back of the testis. Its various parts are connected together
by areolar tissue, and are invested by the various processes
of the fascia, which descends with the testicle. In its course
through the inguinal canal it lies at first between the internal
oblique and the fascia transversalis, the former at times arching
over it; then between the aponeurosis of the external oblique
and the conjoined tendon; and Poupart’s ligament is below.
The left cord is the longer.

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THE VULVA 459

Each cord is composed of the spermatic artery, artery of
the vas deferens, and cremasteric artery, the spermatic veins
from the back of the testis, which receive the veins from the
epididymis to form the pampiniform plexus, a number of
large lymphatics, and the spermatic plexus of the sympathetic,
together with the vas deferens, the layers of fascia which cover
the testicle, and the remains of the peritoneal testicular process.

The inguina! canal (see p. 189 for description) is bounded
behind by the fascia transversalis and the conjoined tendon;
in front by the transversalis and internal oblique above, and the
external oblique aponeurosis below; its floor is formed by the
curving back of: Poupart’s ligament; its roof by the arched
fibers of the internal oblique in apposition with the aponeurosis
of the external oblique.

THE EXTERNAL ORGANS OF REPRODUCTION
(FEMALE)

THE VULVA

The term vulva, or pudendum, includes the mons veneris and
labia, the nymphee and clitoris, the hymen or its remains,
the meatus urinarius, and the vaginal orifice.

The mons veneris is a fatty cushion covering the front of
the pubes, and after puberty is plentifully supplied with hairs.
Below, it divides into the.two labia majora, which, diminishing
in size as they pass downward and backward, unite an inch -
in front of the anus. The two extremities are joined, and form
the anterior and posterior commissures. Between the latter
and the anus is the perineum, and just within the posterior
commissure is a transverse fold, the frenulum pudendi, or
fourchette. Between this fold and the posterior commissure
is a triangular space, the fossa navicularis.

The nymphe, or labia minora, smaller than the above,
run from the middle of the labia majora upward to the clitoris,
each dividing into two folds, the upper pair of which join to
form a prepuce for that organ, and the lower two to form its
frenum. They are continuous externally with the labia majora,
internally with the vagina. The mons veneris is composed

460 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

interiorly of fatty and fibrous tissue; the labia, of areolar
fatty and dartoid tissue with vessels and nerves; the nymphe,
of a plexus of vessels covered by mucous membrane.

The clitoris is the analogue of the penis, consisting, like it,
of two corpora cavernosa united by a septum pectiniforme
and prolonged behind into two crura attached to the pubic
and ischial rami. It also has a suspensory ligament and a
glans enclosed by the nymph. Two erectores clitoridis muscles
are attached to the crura. It has no corpus spongiosum or
urethra. |

Between the clitoris and the vagina, bounded on each side
by the nymphee, is the vestibule, a triangularsspace, in which,
just above the vagina, is the meatus urinarius, one inch below
the clitoris.

The hymen is a mucous fold which more or less completely
occludes the orifictum vagine. It is generally semilunar in
form, concave above, or it may be a complete membrane,
perforate or imperforate, or it may be absent. After labor
its remains form the caruncule myrtiformes.

The glands of Bartholin, the analogues of Cowper’s glands
in the male, are two yellowish bodies on each side of the vaginal
opening, each of which discharges by a single duct between
the hymen and the nymphe.

On each side of the vestibule, behind the nymphe, is a
leech-shaped mass, the bulbus vestibuli. Each consists of a
venous plexus enclosed by a fibrous capsule, and is about one
inch long. In front of these, and connecting them with the
vessels of the clitoris, is a small venous plexus, the pars inter-
media of Kobelt.

THE URETHRA

The female urethra is a mucous canal, 15 inches long, running
downward and forward in the anterior vaginal wall from the
neck of the bladder to the meatus. As in the male, it pierces
the triangular ligament, and is surrounded by the compressor
urethre muscle. It consists of a muscular, a mucous, and
between them an erectile coat. It is supplied with numerous
glands, and just within the meatus near the floor are two
ducts which extend upward for about ? inch. These are called
Skene’s tubules.

—_—

THE UTERUS 461.

THE VAGINA

The vagina extends from the vulva to the uterus, lying
behind the bladder and in front of the rectum, and is about
4 inches long on its anterior wall, 5:to 55 on its posterior, and
is directed from the uterus downward and forward.

Above, it embraces the cervix uteri, and its walls are flattened
from before backward.. It is narrowest at the introitus, or
orificium vagine. Jn front it is in relation with the urethra
and base of the bladder; behind, it is connected with the anterior
wall of the rectum by its lower three-fourths, the cul-de-sac
of peritoneum (Douglas’) separating them above; laterally,
the broad ligaments are attached above, and the levatores
ani below, as well as the rectovesical fascia. Its inner surface
presents a mesial ridge or raphé on the front and back walls,
the columne rugarum, and from them on both sides run out
transverse folds or rugze.

The vaginal mucous membrane is squamous, with papille
here and there. The submucous coat holds many large veins
and some muscular fibers, making a sort of erectile tissue.
The veins form a sort of plexus. The muscular coat comprises
an internal circular and an external longitudinal layer. At
the lower part is the sphincter vaginz, a muscle composed
of striped fibers.

The internal organs include the uterus, tubes, and ovarves.

THE INTERNAL ORGANS OF REPRODUCTION
(FEMALE)

THE UTERUS

The uterus, or womb, is a hollow muscular organ lying in
the pelvis between the bladder and rectum. In the virgin
it is pear-shaped, flattened from before backward, its upper
end looking forward and upward, its lower downward and
backward, forming an angle with the vagina. Above, it is
invested by the peritoneum, which covers its body before
and behind; it covers also the cervix behind, but in front the

462 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

peritoneum is reflected on to the bladder before reaching the
cervix. Its upper and back part is in contact with the small
intestine, its lower and front part with the bladder, the peri-
toneum separating them. The two folds of peritoneum after
investing the uterus are applied to each other, reaching across
to the lateral pelvic walls forming the broad ligaments.

The uterus is 3 inches long, 2 wide, and 1 thick, and it weighs
about 1 ounce. It is divided into a body, fundus, and neck.
The fundus is the convex part above the entrance of the tubes;
the body is the part between this and the neck. In front of

Fia. 75
TUBAL VESSELS
———

ANASTOMOSIS OF FALLOPIAN
UTERINE AND
OVARIAN ARTERIES

HELICINE

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“SUPERIOR VAGINAL
ARTERIES

VAGINAL VENOUS PLEXUS -\

OS UTERI VAGINA CUT OPEN BEHIND

Vessels of the uterus and its appendages, rear view. (Testut.)

the Fallopian tubes, at the upper part of the lateral borders,
the round ligaments are attached, and below and behind them
are the ligamenta ovarica. The cervix is the lower constricted,
rounded part, and around it is attached the vagina. At its
vaginal end is a round opening, the os uteri.

The cavity of the uterus is small; that part within the body
is triangular, flattened anteroposteriorly, and presents at the
superior angles the openings of the Fallopian tubes; also,
at its junction with the neck it is constricted to form the os
internum or isthmus. The cavity of the cervix is barrel-shaped
and flattened anteroposteriorly, presenting on each wall a

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THE UTERUS 463

longitudinal column sending off oblique rugz on each side;
hence its name, arbor vitze uterinus.

The walls of the uterus consist of an outer serous coat (already
described), an inner mucous, and an intermediate muscular.
The muscular coat forms the bulk of the uterus, and consists
of bundles and layers of unstriped fibers which interlace, and
of some areolar tissue supporting them, and of bloodvessels,
lymphaties, and nerves. Three layers are described—an
external transverse layer, some of the fibers being continued
on to the Fallopian -tubes, etc.; a middle layer of intermixed
longitudinal, oblique, and transverse fibers; and an internal
layer, which is circularly arranged at the cervix, forming the
so-called external and internal sphincters. This layer is the
muscularis mucosz of the mucous membrane.

The mucous membrane of the body differs from that of the
eervix. ‘The former is smooth, reddish, with columnar cells,
and presents the ducts of a number of tubular glands which
end by blind, sometimes forked, extremities. In the cermx
it is firmer, and presents numerous saccular and tubular glands
between the ruge of the arbor vite, and below, numerous
papille. The glands are sometimes distended by their secre-
tion, the ducts being choked, and present the appearance of
vesicles; hence their name, ovules of .Naboth. At the upper
part of the cervix the cells are columnar and ciliated; below,
stratified. ,

The ligaments of the uterus are the round ligaments and
several peritoneal folds, namely, two each in) front, behind,
and laterally.

The round ligaments are two cord-like bundles of areolar,
fibrous, and plain muscular tissue, with vessels and nerves,
covered by peritoneum, which run from the upper angle of
the uterus to the internal ring. Each then runs through the
corresponding inguinal canal to end in the mons veneris and
labia. Each measures about 4 or 5 inches in length, and their
direction is upward, forward, and outward. The peritoneum
which invests them is sometimes prolonged (as in the fetus)
for some distance into the inguinal canal, and forms the canal
of Nuck. Generally this canal is obliterated.

The anterior or vesicouterine ligaments stretch between the
bladder and the uterus; the posterior, between the uterus

464. SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

and rectum, hence called the rectowterine, forming a pouch,
the cul-de-sac of Douglas.

The two lateral or broad ligaments pass from the sides of the
uterus to the sides of the pelvis, thus dividing the latter into
two parts. They are formed by the coalescence of the peritoneal
layers investing the anterior and posterior surfaces of the
uterus, and contained between the two layers—the Fallopian
tube at the upper margin; the round ligament below and in
front of the tube; the ovary and its ligament enfolded by the
posterior layer; and the uterine bloodvessels, lymphatics, and
nerves.

THE FALLOPIAN TUBES

The Fallopian tubes, or oviducts, run from the upper angles
of the uterus toward the sides of the pelvis, and near their
termination bend downward, backward, and inward. They
are 3 to 4 inches long, are at first narrow, then enlarge near
the extremity (ampulla), and end in a fimbriated margin, one
of the fimbriz being attached to the ovary. The canal is very
narrow at the uterine end (ostium uterinum), begins to widen
in the outer half to form the ampulla, and at its termination
again narrows (ostium abdominale).

The tubes consist of a peritoneal coat, a muscular coat com-

posed of internal circular and external longitudinal fibers,
and a mucous coat. The latter is continuous with that of the
uterus and with the peritoneum, the epithelium being ciliated
columnar, and it is thrown into longitudinal wrinkles, more
marked in the outer half of the tube.

THE OVARIES

The ovaries are analogous to the testes, and are flattened,
oval bodies, measuring 13 inches long, ? inch wide, and 4
inch thick, each weighing 60 to 100 grains. Of each, the two
sides are free as well as the convex border, the straight border
(hilum) being attached to the broad ligament and admitting
the vessels, ete. Its outer end is attached by the fimbria
ovarica to the Fallopian tube, its inner end to the uterus by
the ligament of the ovary, a dense, fibromuscular cord attached
to the uterus below and behind the tube.

4 » Fo

THE MAMMARY GLANDS 465

The ovary consists of a stroma in which are embedded the
Graafian follicles, and of a covering of columnar cells, the
germinal epithelium. The stroma is invested beneath the
epithelium by a dense fibrous layer, the tunica albuginea,
and consists of connective tissue with numerous cells, as well
as of elastic fibers, With some muscular tissue and bloodvessels.

The Graafian follicles consist of an external fibrous coat,
and beneath it a coat called the ovicapsule, lined internally
with a layer of cells, the membrana granulosa. Within this
last-named layer is the ovum, invested by the discus proligerus,
a layer of cells derived from the membrana granulosa, together
with the liquor folliculi.

THE PAROVARIUM

The parovarium, organ of Rosenmiiller, is a fetal remnant
lying in the broad ligament between the ovary and Fallopian
tube. It consists of several vertical tubes, lined with epithelium,
whose lower ends run toward the hilum of the ovary, and
whose upper ends are united by a horizontal tube, the duct
of Gaertner.

THE MAMMARY GLANDS

These are accessory to the generative system and secrete
the milk. They are two rounded eminences, one on each side
of the thorax, between the sternum and axilla and the third
and seventh ribs. Just below the centre is a conical eminence,
the nipple, which is dark, and is surrounded by a pinkish
areola which darkens in pregnancy. It presents the orifices
of the lactiferous ducts, and consists of vessels mixed in with
plain muscular fibers, and by friction may be made to undergo
erection.

The mamma consists of a number of lobes separated by
fibrous tissue and some adipose tissue. The lobes are divided
and subdivided into smaller lobules, which are in turn made
up of alveoli. Each lobe has an excretory (galactophorous)
duct, and these, about sixteen in number, converge to the
areola, there dilating into ampulle, or sinuses. They then

30

466 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

become smaller again, and surrounded by areolar tissue and

vessels, pass through the nipple to empty on the surface by

separate orifices.

THE DUCTLESS GLANDS
THYROID GLAND

The thyroid gland is a very vascular organ, situated at the
front of the neck, overhanging the upper rings of the trachea
and laterally extending as high as the oblique line on the ala
of the thyroid cartilage, and as low as one inch above the upper
border of the sternum, when the head is extended. It weighs
about one ounce; slightly heavier in the female. It has three
lobes—two lateral connected by an isthmus; and one third
or middle lobe—presenting (the former) two surfaces, and an
anterior and posterior border. It is firmly attached to the
cricoid cartilage and posterior fascia of the trachea by two
lateral or suspensory ligaments, and its lobes and isthmus are
enclosed within a fibrous capsule derived from the pretracheal
portion of the deep cervical fascia.

The external surface of the lateral lobes is covered by the
skin, superficial fascia, a portion of the platysma muscle,
deep fascia, sternomastoid, anterior belly of omohyoid, sterno-
hyoid, and sternothyroid muscles. The internal surface is
moulded over the thyroid and cricoid cartilages, the trachea,
inferior constrictor muscle, and posterior part of cricothyroid
muscles, the esophagus (mostly on the left), the superior and
inferior thyroid arteries, and recurrent laryngeal nerves.

The anterior borders are thin, and incline obliquely from
above downward and inward to the median line. The posterior
borders are réunded and rest on the carotid sheath.

The middle lobe arises from the upper part of the isthmus
and left lobe, extending as high as the middle of the hyoid
bone in front of the thyroid cartilage.

The isthmus lies on the second and third ring of the trachea,
and measures about 4 inch in breadth and depth. It has the
cricothyroid artery and vein above it, and the lower border
is in relation with the inferior thyroid veins. Care should
be taken during tracheotomy not to injure these structures.

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THYMUS GLAND 467

The superior and inferior thyroid arteries, sometimes a
_ thyroidea ima branch from the innominate artery, supply the
gland. ‘The veins are the superior and inferior accessory
thyroids, a transverse, and sometimes a middle thyroid vein.
The lymphatics drain into the superior and inferior set of deep
cervical nodes, and the nodes in front of the bifurcation of the
trachea; also an ascending trunk passes to the node in front
of the larynx. The nerves are derived from the inferior laryngeal
and the middle and inferior cervical ganglion of the sympathetic.
The accessory thyroids are small isolated masses of thyroid
tissue sometimes present, found about the lateral lobes of the
thyroid gland in the sides of the neck or just above the hyoid
bone.

PARATHYROID GLANDS

The parathyroid glands are small reddish-brown bodies,
composed of masses of cells, arranged in a more or less reticular
manner, with numerous intervening bloodvessels. They are
usually found one on either side (the superior) at the level of
the lower border of the cricoid cartilage, behind the junction
of the pharynx and esophagus, and in front of the prevertebral
fascia. The lower are just below the lower edge of the lateral
lobe one on either side. There are usually four, but may be
only three, or, again, as many as six or eight. Their location
is variable.

THYMUS GLAND

The thymus gland is a temporary organ, attaining its full
size at the end of the second year and gradually shrinking
until puberty, when it entirely disappears. Consists of two
lateral lobes placed in close contact along the median line. It
is found in the superior mediastinum, covered by the sternum
and the origins of the sternohyoid and sternothyroid muscles;
below, it rests upon the pericardium, and separated from the
arch of the aorta and great vessels by fascia. In the neck it
lies on the front and sides of the trachea beneath the sterno-
hyoid and sternothyroid muscles. It is pinkish gray in’ color.
About 2 inches in length, 14 inches in breadth, below, and
about ¢ inch in thickness.

468 SPLANCHNOLOGY, OR ANATOMY OF THE VISCERA

SPLEEN

The spleen is the largest of the ductless glands. It is found
in the left hypochondrium, entirely surrounded by peritoneum,
except around the hilum, which attaches it to the fundus
of the stomach (the gastrosplenic omentum). It is purplish
in color, oblong, flattened, tetrahedral form, soft, of a very
friable consistency, and highly vascular. It measures 5 inches
in length, 2 to 3 inches in width, and 1 to 14 inches in thickness
at the centre. It weighs 65 ounces.

The Relations.—The external or phrenic surface is in rasta

with the under surface of the diaphragm, which separates —

it from the ninth, tenth, and eleventh ribs on the left side,
and the intervening lower border of the lung and pleura above.
The gastric surface is concave, and is in relation with the pos-
terior part of the fundus of the stomach and the tail of the
pancreas. It presents near its inner border a long fissure,
the hilum, in which are several openings for the splenic vessels
and nerves to enter and leave the organ. The renal surface
is flattened somewhat and is in relation with the outer and
upper surface of the left kidney, and sometimes the suprarenal
capsule.

The spleen is attached to the stomach by the gastrosplenic
omentum; between its layers pass the vasa brevia and left
gastroepiploic arteries and veins. ‘The lienorenal ligament
is a peritoneal fold which attaches it to the upper pole of the
left kidney, and the phrenocolic assists to support it by its
attachment to the diaphragm.

The arteries are the splenic from the celiac axis. The vein
is the splenic, which drains into the portal system.

The lymphatics drain into the splenic nodes, and the latter
empty into the celiac nodes. The nerves are derived from the
splenic plexus of the sympathetic system.

SUPRARENAL GLANDS

The suprarenal glands are two flattened bodies, of a yellowish
color, found in the epigastrium, lying behind the peritoneum,
and above and in front of the upper extremity of each kidney.

COCCYGEAL GLAND 469

They are triangular in shape, 13 to nearly 2 inches in length,
less in width, and } of an inch in thickness.

The relations of the right suprarenal gland. It lies behind
the inferior vena cava and the right lobe of the liver, and in
front of the diaphragm; below is the kidney. The left, slightly
larger than the right, lies on the left crus of the diaphragm;
below is the kidney.

The arteries are the suprarenal from the abdominal aorta,
a branch from the renal and one from the phrenic artery.
The veins empty into the inferior vena cava on the right side,
and into the renal vein on the left side. The lymphatics drain
into the nodes at the corresponding sides of the aorta. The
nerves are derived from filaments of the celiac and renal plexuses.
The accessory suprarenal glands are often to be found in the
tissue around the suprarenals.

CAROTID GLANDS

The carotid glands or bodies are small reddish-brown bodies,
oval in shape, their long diameter measuring 4 of an inch.
They are found in the cervical region, at the bifurcation of
the common carotid artery into the internal and external
carotid trunks.

COCCYGEAL GLAND

The coceygeal gland, or body, or Luschka’s gland, is as
large as a millet seed, found at the tip of the coccyx. It is
connected with the middle sacral artery.

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QUESTIONS ON SPLANCHNOLOGY

THE ORGANS OF RESPIRATION

Describe each of the cartilages of the larynx.

Of what are the true vocal cords composed?

To what part of the arytenoid cartilages are the true vocal cords
attached?

Name the branches of each bronchus.

What is the lowest point the pleure reach?

Which lung is the larger?

Describe the fissure of each lung.

Locate the apices of the lungs in the neck.

THE ORGANS OF DIGESTION

Name the salivary glands, giving the location of each.

Give the names of the ducts of the salivary glands, and tell where
they enter the mouth.

How long is the esophagus?

Give the relations of the esophagus in the neck and in the thorax.

Into what regions is the abdomen divided?

At what place are the greater and lesser sacs of the peritoneum
continuous?

Trace the peritoneum in the median line from above downward
and back again to the starting point. .

Trace the peritoneum transversely at the level of the foramen of
Winslow.

Where can the pancreas be reached by cutting only one layer of
peritoneum after the belly is opened?

Describe the peritoneal relations of the duodenum, rectum, and
bladder.

Name the pouches or cul-de-sacs formed by the peritoneum.

Give the relations of the stomach.

Trace the duodenum through its various curves, from the pylorus
to the jejunum.

How are the large and small intestines to be distinguished?

Describe the appendix vermiformis.

bie does the sigmoid flexure of the colon begin, and where does
it en

What are the relations of the duodenum?

Describe the ileocecal valve.

What is the cul-de-sac of Douglas?

What are the lobes of the liver?

Which lobe is between the gall-bladder and longitudinal fissure?

What are the surfaces of the liver?

How low down does the free margin of the liver normally extend?
hs Give the structures in relation with the inferior surface of the

ver.

Where does the gall-duct empty?

Locate the gall-bladder on the abdominal wall.

Give the relations of the pancreas.

THE URINARY ORGANS

Just where do the kidneys lie?

How can you tell to which side a kidney belongs?
Give the relations of the ureters.

What are the ligaments of the bladder?

THE ORGANS OF REPRODUCTION

Where is the prostate located? |
Describe the male urethra.
- Name the coverings of the testicle.
Locate the internal abdominal ring.
Describe precisely the inguinal canal.
What is the relation, as to position, of the epididymis to the testicle?
What part of the vaginal wall is in contact with the peritoneum?
Describe the broad ligaments of the uterus, giving the relations of
the contained structures.
How far down does the peritoneum come anteriorly on the uterus?
Describe the Fallopian tubes.
How large is an ovary?

THE DUCTLESS GLANDS

Of what parts is the thyroid gland composed, and just where are
they situated?

What are the surfaces of the spleen?

Opposite what ribs in the midaxillary line should the spleen lie?

Does the spleen vary much in size?

Give the relations of the spleen.

A SELECTED LIST OF STATE BOARD -
EXAMINATION QUESTIONS

The following questions are taken from recent examinations held
by the Medical Examiners of the several States, and are given here as
additional assistance to the student preparing himself in the subject.

The references in black type indicate the pages where information
will bé found supplying correct answers to questions.

1. Describe the shoulder-joint. Pages 132-135.

2. Describe the appendix vermiformis and give its relations.
Page 433.

3. Describe the prostate gland and give its relations. Page 451.
ieee the tibia and give in detail its articulations. Pages
ae Describe the fascia lata and give its regional anatomy. Page

6. Describe the female perineum and the relations of its muscles
and fascie. Pages 189 and 193.

7. Describe the gross anatomy of the stomach and give its relations.
Pages 427-429.

8. Describe the distribution of the peritoneum. Pages 423-425.

9. Locate the following bony. points: (a) Mastoid process, (b)
olecranon, (c) external malleolus, (d) acromion, (e) spine of ischium.
Pages 42, 80, 86, 97, and 105.

10. State the names and give the attachments of the muscles of
mastication. Pages 173-175.

11. Describe the femoral artery as to (a) origin, (b) course, (c)
branches. Page 277.

12. Describe the inferior vena cava. Page 292.

13. State the origin and give the course of the musculospiral nerve
(nervous radialis) and mention the names of two of its terminal
branches. Page 363.

14. Describe the spleen and give its relations to surrounding struc-
tures and organs. Page 468.

15. State origin, course, and distribution to the stomach of the left
vagus (pneumogastric) nerve. Page 350 and 353.

rte the minute anatomy of the lobules of the liver. Pages 439
an

17. What are the muscles attached to (a) the posterior border of:
the ulna, (b) the spine of scapula? Pages 176, 200, 203, 204, 207,
211, and 212.

18, Give the topographic anatomy of (a) the internal abdominal
ring, (b) the external abdominal ring. Pages 186 and 188.

_ 19. Describe the articulation of the head of a rib, in the middle
of the series, with the vertebre. Pages 121-122.

20. Give a detailed description of the rectum. State the blood
supply and the nerve supply of the rectum. Pages 435, 436,
and 437.

21. Give the articulations of the inferior turbinate bone. Page 62.

22. Where are the medulla oblongata, the pons Varolii, and the
cerebellum located, and how are they separated from the cerebral
hemispheres? Pages 307, 309, and 310.

23. Name the nerves that supply the muscles of the forearm and
hand. Pages 360, 361, 363, and 364.

24. Where does the internal carotid artery commence? Where does
it terminate and into what does it divide? Pages 256 and 258.

25. What bones form the articular surface of the knee-joint? Name
the ligaments of the knee-joint. Page 146.

26. Name the tunics or coats of the eye from without inward; also
the refracting media, or humors, of the eye. Pages 382, 383, and 386.

27. Name the branches of (a) the ascending aorta; (b) arch of the
aorta. Page 248.

28. Give origin, insertion, action, and nerve supply of the Brachialis
anticus muscles. Pages 203 and 204.

29. Where does the right lymphatic duct empty its contents? What
part of the body does it drain? Page 296.

a Describe in detail the movements of the knee-joint. Pages
149-151.

31. What is the nerve supply of the flexor group of muscles of the
forearms? Page 209.

32. What are the surface points for the following: Bifureation of
the trachea; gall-bladder; spleen; termination of the spinal cord;
kidney? Pages 304, 406, 440, 444-446, and 468.

33. Describe the course of the portal vein, and give its relations.
Page 295.

34. Describe the venous and arter ial blood supply of the ovaries.
Pages 273 and 292.

35. What are the surface spelen of the liver? Pages 437 and
439.

36. Describe the pleural sac, including attachments and contents.
Pages 406-407, 408-410.

37. Describe the arrangement of the dura mater and state functions.
Page 306-307.

38. Give the anatomical relations of the stomach. Page 428.

39. What is Poupart’s ligament? State origin and insertion, and
the structures which pass under it. Pages 185, 186, 188, 221, 227,
293, and 367.

40. State origins of vertebral, internal mammary, and _ basilar
arteries. Pages 259, 260, and 262.

41. Name the largest cranial nerve. How many roots has it, and
what is its superficial origin? Why is it called a compound nerve?
Pages 338-339.

42. Describe the second nerve, giving its course and position. What
is its exclusive distribution? Pages 335-337.

43. Locate and give the gross anatomy of the medulla oblongata.
Pages 307-308.

44. Describe the occipital bone. Pages 33-36.

45. Name the carpal bones. Page 92.

ie Name varieties of articulations. Give example of each. Page
114.

47. Give origin and distribution of great sciatic nerve. Page 371.

48. Give origin, insertion, and nerve supply of Quadratus lumborum,
Brachialis anticus, Orbicularis oculi, and Sartorius. Pages 170, 203,
204, 220, 224, and 225.

49. Describe the epithelium of the pharynx. Page 421.

50. What arteries form the circle of Willis? Page 261.

51. What and where is the pituitary body? Page 318.

52. Describe the upper third of the femur. Page 99.

53. Give the class of joint, the articulation, and ligaments of the
shoulder joint. Page 132.

54. Trace blood from the heart by way of the subclavian artery to
the circle of Willis, naming the arteries uniting to form the circle.
Pages 258-261.

55. Name the muscles of the anterior chest, and give origin and
insertion of the largest one of them. Page 196.

56. Name the main superficial venous trunks of the upper arm,
describing one of them. Page 290.

57. Describe the gall-bladder and the bile-ducts. Pages 440 and

58. Describe the great sciatic nerve. Page 371.

59. Describe the rectum. Page 435.

60. Name the bones of the lower extremity. Page 93.

61. Name and locate the valves of the heart. Pages 243-246.

62. Locate the spleen and describe its gross anatomy. Page 468.

63. Describe in full the pulmonary veins. Page 283.

64. Describe the contents in Scarpa’s triangle and give their rela-
tions. Page 277.

65. Name the lobes and ventricles of the brain. Pages 310-328.

66. Name the ligaments supporting the uterus and describe its
blood supply. Page 273, 274, 463, and 464.

67. Give the general classification of bones. Page 17.

68. Name the bones of the upper extremity. Page 77.

69. Describe the diaphragm, giving origin, insertion, nerve supply,
and action. Pages 194 and 195.

INDEX

A

ABDOMEN, fascize of, 184
muscles of, 184
Abdominal aorta, 268
ring, external, 186
internal, 188
Abductor hallucis muscle, 237
minimi digiti, 238
pollicis muscle, 215
Accessorius muscle, 237
Acetabulum, 98
Acromioclavicular articulation, 130
Acromion process, 80
Adductor brevis muscle, 229
hallucis, 237
longus muscle, 228
magnus muscle, 229
minimus muscle, 229
obliquus pollicis muscle, 215
pollicis, 215
transversus pollicis muscle, 215
tubercle, 101
Air sinuses, 71
Alar ligaments, 121
Alveolar nerve, 341
Anconeus muscle, 211
-Angeiology, 241
Antecubital space or fossa, 265
Antrum of Highmore, 54
Aorta, 247
Appendix, vermiform, 433
Aqueduct of Fallopius, 44
of vestibule, 44
Aqueous humor, 386
Arachnoid, 303, 307
Arbor vite, 311, 463
Arch, subpubic, 99
Arcuate ligaments, 194

Arm, fascize of, 200
Arteries, alveolar, 255

anastomotica magna, 264
aorta, 247
abdominal, 268
thoracic, 267
arteria centralis retinze, 258
auricular, anterior, 254
posterior, 253
axillary, 263
basilar, 260
brachial, 264
brachiocephalic, 250
bronchial, 268
of bulb, 275
carotid, common, 251
external, 251
internal, 255
celiac axis, 720
cerebral, 258
choroid, anterior, 258
ciliary, 258
circle of Willis, 261
circumflex (of axillary), 264
external, 278
iliac, deep, 276
superficial, 277
internal, 278
colica, 273

communicating, posterior, 258

coronary, 248
of corpus cavernosum, 275
dental, inferior, 255
dorsal, of penis, 276
dorsalis pedis, 280
epigastric, deep, 276
superficial, 262
esophageal, 268
ethmoidal, 257

472

Arteries, facial, 253
transverse, 254
femoral, 277
frontal, 258
gastric, 270
gastroépiploica, dextra, 270
sinistra, 270
gluteal, 274
hemorrhoidal, middle, 274
superior, 273
hepatic, 270
hyoid, 252
ileocolic, 273
iliac, 274
external, 276
internal, 274
innominate, 250
intercostal, 268
superior, 262
interosseous, 267
lacrymal, 256
laryngeal, inferior, 261
superior, 252
lingual, 252
lumbar, 269
mammary, internal, 262
maxillary, internal, 254
medullary, 18, 19
meningeal, middle, 254
small, 255
mesenteric, inferior, 273
superior, 270
nasal, 258
obturator, 275
occipital, 253
ophthalmic, 256
ovarian, 273
palatine, descending, 255
pancreatic, 270
perineal, 275
peroneal, 281
pharyngeal, ascending, 253
phrenic, 268
plantar, 281
arch, 281
digital, 282
popliteal, 279
profunda, femoris, 278
inferior, 264
superior, 264
pterygoid, 255

INDEX

Arteries, pterygopalatine, 255
pudie, internal, 275
pulmonary, 246, 247
pyloric, 270
radial, 265
renal, 273
sacral, lateral, 274

middle, 269
sciatic, 276
sigmoid, 273
spermatic, 273
splenic, 270
subclavian, 258
subscapular, 263
superficialis vole, 266
supraorbital, 257
suprarenal, 273
suprascapular, 261
temporal, 254, 255
thyroid axis, 261
inferior, 261
superior, 252
tibial, 280, 281
transverse, cervical, 262
triangle, Scarpa’s, 277
tympanic, 254, 256
ulnar, 266
uterine, 274
vaginal, 274
vasa brevia, 270
intestini tenuis, 271, 272 -
vertebral, 259 -
vesical, 274 -
Vidian, 255 -
Articulations, acromioclavicular,
130
ankle-joint, 152
axis with atlas, 118
with occipital bone, 121
carpus, 140
classification of .114
costal cartilages and sternum,

elbow-joint, 135
hip-joint, 141
intercostal, 123
knee-joint, 146

of lower extrentity, 141
occiput and atlas, 120
of pelvis, 127
radioulnar, 138, 139

ait
ap alee ae I a

PS Sa ee al ie fs eal ~s a

INDEX 473

Articulations, ribs with vertebra, ; Bones, fibula, 105

121 | flat, 18
sacrum and coccyx, 128 | of foot, 106
and ilium, 127 of forearm, 86
and ischium, 127 frontal, 38
scapula, proper ligaments of, 131 = of hand, 92
shoulder-joint, 132 | of head, 33
sternoclavicular, 129 humerus, 82
of sternum, 124 hyoid, 31
temporomaxillary, 124 ilium, 93
two pubic bones, 129 incus, 390
of upper extremity, 129 irregular, 18
of vertebral column, 115 ischium, 96
of wrist, 139 lacrymal, 60
Arytenoid cartilage, 400 of leg, 103
Astragaloscaphoid ligament, 154 long, 18
Astragalus, 107 of lower extremity, 93
Auditory nerve, 348 malar, 58
Auerbach, plexus of, 429 malleus, 390
Auricular arteries, 253, 254 maxillary, inferior, 62
. muscle, 169 superior, 52
Axilla, 262 metacarpals, 92
Axillary artery, 263 nasal, 60
nodes, 301 occipital, 33
veins, 290 os calcis, 106
Axis, ligaments of, 118 innominata, 93
Azygos uvule muscle, 164 magnum, 92
veins, 291 pubis, 95
palate, 54
ee parietal, 36
patella, 102
Barkow, ligament of, 135 of pelvis, 93
Bartholin’s glands, 460 pisiform, 92
Basilar artery, 260 radius, 90
Basilic veins, 290 | Tibs, 73
Biceps cubiti muscle, 202 sacrum, 28
femoris muscle, 226 scaphoid, 92
Bicipital tuberosity, 90 scapula, 79
Bladder, 449 short, 18
ligaments of, 449 skull as a whole, 64
lymphaties of, 298 sphenoid, 46
Bones, astragalus, 107 stapes, 390
atlas, 21° sternum, 72
axis, 22 temporal, 39
carpal, 92 tibia, 103
clavicle, 78 | trapezium, 92
coccyx, 28 turbinated, 51, 61
costal cartilages, 73 ulna, 86
ethmoid, 50 unciform, 92
of face, 52 | of vertebral column, 19

femur, 99 ; | vomer, 57

474. ' INDEX

Bones, Wormian, 64
Brachial artery, 264
ligaments, 202
plexus, 357
Brachialis anticus muscle, 203
Brachiocephalic artery, 250
Brachioradialis muscle, 210
Brain. See Encephalon.
ventricles of, 326
Bronchi, 411, 412
Bronchial artery, 268
Buccal nerve, 3438
Buccinator muscle, 171
Bulbocavernosus muscle, 192
Bulbus vestibuli, 460
Bursa above knee, 151
prepatellar, 151
subcrural, 151

C

Crcum, 432
Calcaneoastragaloid ligament, 154
Calcaneocuboid ligament, 154
Caleaneoscaphoid : ligament, 154
Calcarine fissure, 324
Camper’s fascia, 184
Canals, crural, 220
dental, 53
ethmoidal, 51
of Huguier, 40
Hunter’s, 226
inguinal, 189
palatine, 53
spinal, 31
Vidian, 50
Capitellum, 85
Carotid arteries, 251, 255
tubercle, 23
Carpal bones, articulations of, 92
Carpus, articulations of, 140
Cartilages, arytenoid, 400
cornicula laryngis, 401
costal, 73
ericoid, 400
cuneiform, 401
epiglottis, 401
of nose, 396
of Santorini, 401
semilunar, 148

et Weed thyroid, 399
of Wrisberg, 401
_Caudate nucleus, 328
| Cavernous sinus, 288
| Cavity, cotyloid, 98
sigmoid, 88
Celiac axis, 270
Cephalic veins, 290
Cerebellar veins, 287
Cerebellum, 310
lobes of, 310
peduncles of, 310
Cerebral arteries, 258
_ veins, 286
Cerebrospinal axis, 303
'Cerebrum, 319
Cervical artery, transverse, 262
nerves, 355
nodes, 301
plexus, 355
Cerviculis ascendens
180
Chassaignac’s tubercle, 23
Chondroglossus muscle, 161
Choroid, 383
plexus, 329
Ciliary artery, 258
muscle, 384
Circle of Willis, 261
Circular sinus, 288
Cireumflex arteries, 264, 278
iliac arteries, 276, 27 7
nerve, 359
Claustrum, 329
Clavicle, 78
Clinoid processes, 47, 48
Clitoris, 460
Clivus, 45
Coccygeal nerves, 368
Coccygeus muscle, 192
Coccyx, 28
Cochlea, 393
Collateral fissure, 324

muscle,

Colon, 483

Columns of cord, 304, 305
Compressor urinz muscle, 193
Condyles of humerus, 84, 85
Conjunctiva, 381

_Conoid ligament, 130

ae triangular ligament of, 184,
190

INDEX

Constrictor urine muscle, 193
Coracobrachialis muscle, 202
Coracoclavicular ligament, 131
Coracoglenoid ligament, 133
Coracohumeral ligament, 133
Coracoid processes, 80
Cord, spermatic, 458
spinal, 303
Coronoid process, 63, 86
Corpora albicantia, 317
quadrigemina, 314
Corpus callosum, 326
fimbriatum, 329
striatum, 328
Corti, organ of, 391
Costal cartilage, 43
Costoclavicular ligament, 130
Costocoracoid ligament, 196
Cotyloid cavity, 98
ligaments, 141
notch, 98
Cowper’s glands, 454
Cranial nerves, 334
Cranium, interior of, 68
fossa of, 68, 69
Cremaster muscle, 187
Cremasteric fascia, 187
Crest, obturator, 96
Cricoid cartilage, 400
Crucial ligaments, 147, 148
Crura cerebri, 313, 325
of diaphragm, 194
Crural nerves, anterior, 367
ring, 220
sheath, 220
Crureus muscle, 225
Crusta of crus cerebri, 313, 325
Crystalline lens, 386
Cuboid bone, 108
Cuneiform bones, 108, 109
cartilage, 401
Cutaneous nerves, 359
external, 367

D

DeE.ToIpEvs muscle, 200

Dental artery, inferior, 255
nerves, inferior, 343

Dentate fissure. See Hippocampal.

475

| Diaphragm, muscles of, 194

_Diencephalon, parts included un-
der, 315
| Digastric muscle, 158
_Diploic vein, 289
Dorsal artery of penis, 276
fascize, 178, 179
nerve, 364
| vein, 294
_Dorsalis pedis artery, 280
Douglas, cul-de-sac of, 423, 436
Duct, ejaculatory, 458
common, 441
cystic, 441
hepatic, 441
nasal, 382
pancreatic, 443
thoracic, 296
Duodenum, 430
Dura mater, 306

E

Ear, 387
cochlea, 393
internal, 392
labyrinth, 392
organ of Corti, 391
semicircular canals, 393
spiral canal, 394
vestibule, 392
Kjaculator urine muscle, 192
Ejaculatory duct, 458
Eminence, iliopectineal, 96
Eminentia articularis, 40
collateralis, 329
Emissary veins, 289
Encephalon, 306
Epididymis, 456
Epiglottis, 401
Epiphysis cerebri. See Pineal gland.
Erector penis muscle, 192
spine muscle, 179

-| Ethmoid bone, 50

Ethmoidal artery, 257
canals, 69
Extensor brevis digitorum, 236
hallucis, 236
pollicis, 213
carpi radialis, 210

476 } INDEX

Extensor carpi radialis longior, | Fascie, obturator, 190
210

ulnaris, 211
communis digitorum, 210
indicis, 212
longus digitorum, 231
pollicis, 212
minimi digiti, 211

ossis metacarpi pollicis, 212

proprius hallucis, 231
Eye, 380

aqueous humor, 386

choroid, 383

ciliary muscle, 384

cornea, 383

crystalline lens, 386

iris, 385

retina, 385

sclerotic, 382

vitreous body, 386
Eyeball, 382
Eyebrows, muscles of, 170, 381
Eyelid, muscles of, 170

F

Factau artery, 253
transverse, 254
nerve, 345
veins, 285
Fallopian tubes, 285
Falx cerebelli, 306, 464
cerebri, 306
Fasciz, 155
of abdomen, 184
of arm, 202
Camper’s, 184
Colles’, 184, 190
cremasteric, 187
dorsal, 178
of foot, 235
of forearm, 204
of hand, 214
iliac, 189
infundibuliform, 189
ischiorectal (anal), 191
lata, 219
of leg, 230
lumbar, 179
of neck, 156

palmar, 214
of pelvis, 190
| of perineum, 189, 190
| plantar, 235
| prevertebral, 158
_ of pyriformis, 191
| rectovesical, 191
| of Searpa, 184
temporal, 174
of thoracic region, 195

_ transversalis, 188

of upper extremity, 202
| | Rates, pillars of, 164
_ Femoral artery, 277 :

ring, 188

veins, 293
' Femur, 99

fossa of, digital, 100

tubercle of, 100
Fibula, 105

styloid process of, 105

Glaserian, 40

longitudinal, great, 330
precentral, 323
pterygomaxillary, 66
of Rolando, 323
sphenoidal, 66
sphenomaxillary, 66
of spinal cord, 354
of Sylvius, 322, 323
Flexor accessorius, 237
brevis digitorum, 237
hallucis, 237
minimi digiti, 216
pollicis, 215
carpi radialis, 205
ulnaris, 207
longus digitorum, 234
hallucis, 235
pollicis, 209
profundus digitorum, 207
* sublimis digitorum, 207
Flood’s ligament, 133
Fontanelles, 37
Foot, bones of, 18 .
fascize of, 235
muscles of, 235
Foramen lacerum, 69

Fissures, cerebral, 322, 323, 324
great transverse of Bichat, 329

| ee es Se

Re eT ee ee ee

4
y
:

INDEX

Foramen of Monro, 319 )
obturator, 98 |
| Gastric artery, 270

optic, 47

ovale, 69

rotundum, 49

spinosum, 50

thyroid, 98

of Vesalius, 50

of Winslow, 424
Foramina, intervertebral, 31

of Scarpa, 54

of Stenson, 54

Thebesti, 243 )
Forearm, bones of, 86 |

fascia of, 204

ligaments of, 138, 139
Fore-brain, parts derived from, 315
Fornix, 327
Fossa capitis, 100

coronoid, of humerus, 85

digital, of femur, 100

glenoid, 40

nasal, 69

olecranon, 86

ovalis, 248 -

pituitary, 47

radial, 85

sigmoidea, 42
_ sphenomaxillary, 67

temporal, 66

zygomatic, 66
Frontal nerve, 340

G

GALL-BLADDER, 440
Ganglion, cervical, inferior, 376
middle, 376
superior, 374
Gasserian, 338
geniculate, 341, 342, 345
impar, 374
jugular, 349
lenticular (ciliary), 341
Meckel’s, 341
ophthalmic, 340
otic, 344
petrous, 349
of root, 350

submaxillary, 344

477

Ganglion, thyroid, 376
of trunk, 350

vein, 295
'Gastrocnemius muscle, 233

' Gemelli muscle, 222

Geniculate bodies, 314, 316

_Geniohyoglossus muscle, 160
~Geniohyoideus muscle, 160

Genitocrural nerve, 366
Gimbernat’s ligament, 186
Glands, Bartholin’s, 460
Cowper’s, 454
Luschka’s, 469
mammary, 465
Meibomian, 381
parathyroid, 467
parotid, 417
pineal, 315
prostate, 451
salivary, 417
sublingual, 418
submaxillary, 418
suprarenal, 468
‘thymus, 467
thyroid, 466
Glaserian fissure, 40
Glenoid cavity, 81
fossa, 40
Glossopharyngeal nerve, 398 »
Gluteal artery, 274
lines, 95
nerves, 370
ridge, 101
vein, 294
Gluteus maximus evict, 221
medius muscle, 221
minimus muscle, 221
Gracilis muscle, 229
Groove, optic, 46
Gyres, cerebral, 322, 323, 324

H

HAanp, bones of, 92
fascize of, 214
Head, bones of, 33
lymphatics of, 301
veins of, 285
Heart, 241

478 . INDEX

Heart, veins of, 283
Hemorrhoidal arteries, 273, 274
plexus, 294
Hepatic artery, 270
veins, 292
Hiatus Fallopii, 43
Highmore, antrum of, 54

|
/

)

| Interclavicular ligament, 130
Intercondylar notch, 101

_Intercostal artery, 268

superior, 262
articulation, 123
nerve, 364
veins, superior, 285

Hind-brain, parts derived from, Intercostales muscle, 198 »

307
Hippocampus major, 329
Huguier, canal of, 40
Humerus, 82

condyles of, 84, 85
Hunter’s canal, 226
Hymen, 460
Hyoglossus muscle, 161
Hyoid artery, 252

bone, 31
Hypoglossal nerve, 353
Hypophysis cerebri, 318

I

ILEOCECAL valve, 433
Ileocolic artery, 273
Ileum, 432
Iliac arteries, 274
fascia, 189
veins, external, 293, 294
lliacus muscle, 220
lIliocostalis cervicis muscle, 180
dorsi muscle, 180
lumborum muscle, 180
lliofemoral ligament, 143
Ilohypogastric nerve, 366
Ilioinguinal nerve, 366
Iliolumbar ligament, 127
Ilopectineal eminence, 95
line, 96
Iliopsoas muscle, 220
lliotibial band, 219
lliotrochanteric ligament, 144
Ilium, 93
Incus, 390
Infraspinatus muscle, 200
Infundibuliform fascia, 189
Inguinal canal, 189
nodes, 298
Innominate artery, 250
vein, 284

_Interosseous artery, ‘267
nerve, posterior, 364

_Interspinales muscle, 182

_Interspinous ligaments, 117
_Intertransversales muscle, 182
_Intertransverse ligaments, 118

-Intertrochanteric line, antares 101

posterior, 100
Intervertebral foramina, 31
Intestine, large, 432

small, 430

“Tris, 385
_Ischiocavernosus muscle, 179
_Ischiofemoral ligament, 145

/

Ischium, bones of, 96

J

| JEJUNUM, 432
Joints, ankle-, 152
apposition of surfaces of, 114
classifications, 114
elbow-, 135
of foot, 153
general structure of, 113
hip-, 141
ilosacral, 127
knee-, 146
limitation of motion of, 115
radiocarpal, 139
sacroiliac, 127
shoulder-, 132
symphysis pubis, 129
tibiofibular, inferior, 152
upper, 151
wrist-, 139
Jugular veins, 285, 286

K
KOpNeys, 443

lymphatics of, 299
Knee, burs above, 149

eee he eee

L

LABIA majora, 459
Labyrinth of ear, 392, 394
Lacrymal apparatus, 382
artery, 256
bones, 60
nerve, 340
Lacteals, 299
Lamina cinerea, 319

Laryngeal artery, inferior, 261

superior, 252

nerves, 352
Larynx, ligament of, 401, 402

muscles of, 402

saccule of, 403

ventricles of, 403
Latissimus dorsi muscle, 176
Legs, bones of, 103

fasciz of, 230
Lenticular nucleus, 328
Levator anguli scapule, 166

ani muscle, 192

palati muscle, 164

Levatores costarum muscle, 240

Ligamenta alaria, 151
brevia, 209
longa, 209
mucosa, 209

Ligaments, alar, 121
of ankle, 153
arcuate, 194
astragaloscaphoid, 154
-atlas, 118
axis, 118
of Barkow, 135, 145
of Bertini, 144
of Bigelow, 144
of bladder, 449
calcaneoastragaloid, 153
caleaneocuboid, 153
caleaneoscaphoid, 153
check, 121
conoid, 130
Cooper’s, 186
coracoclavicular, 131
coracoglenoid, 133
coracohumeral, 133
coronary, 148
costoclavicular, 130
costocoracoid, 196

INDEX . 479

|
/

.

Ligaments, costosternal, 123
cotyloid, 141
crucial, 147, 148
Flood’s, 133
Gimbernat’s, 186
glenoid, 133
glenoideobrachiale, internal, 134
glenoideohumeral, 134
Henle’s, 187
Hesselbach’s, 187
Hey’s, 219
iliofemoral, 143
iliolumbar, 127
of iliosacral joint, 127
iliotrochanteric, 144
interclavicular, 130
intercostal, 123
interosseous, of forearm 138,
interspinous, aa
intertransverse, 118
ischiofemoral, 145
of larynx, 401, 402, 403
of liver, 437
oblique of forearm 138
obturator, 98
occipitoatlantal, 120
occipitoaxial, 121
odontoid, 121
orbicular, 138
palpebral, 170
plantar, long, 154
- Poupart’s, 186

pterygomaxillary, 163
pubofemoral, 145
rhomboid, 130
sacrosciatic, 128
of scapula, 131
Schlemm’s, 133
spinoglenoid, 131
of Struthers, 202
stylohyoid, 32
stylomandibular, 126
supraspinous, 117
suspensory, of penis, 184
tarsus, 153
transverse, humeral, 134

inferior, 131

of knee, 148

superior, 131
trapezoid, 130
triangular, of Colles, 184

480

ee triangular, of urethra,
19
at wrist, 139
of uterus, 463
. of Zinn, 172
Ligamentum mucosum, 151
nuche, 117
patelle, 147
subflavum, 117
Linea alba, 185
aspera, 101
quadrati, 100
semilunaris, 185
transverse, 185
Lines, gluteal, 95
iliopectineal, 96
intertrochanteric, 100
popliteal, 104
Lingual artery, 152
nerve, 344
veins, 286
Lingualis muscle; 161
Lingula pulmonis, 410
Liver, 4387
ligaments of, 437
lymphaties of, 299
Lobes of brain, 322
of cerebellum, 310
insula, 324
island of Reil, 324
of liver, 439
of lungs, 410
occipital, 323
parietal, 323
temporal, 324
Locus niger, 325
Longissimus capitis muscle, 181
cervicis muscle, 180
dorsi muscle, 181
Longitudinal fissure, great, 181
sinuses, 287
Longus atlantis, 168
capitis, 168
colli, 166
Lumbar artery, 269
fascia, 179
nerves, 365
plexus, 366
veins, 291, 292
Lumbosacral cord, 369
Lungs, 408

INDEX

Lymphatic duct, right, 296
system, 296
vessels and nodes of lower

extremity, 298

Lymphatics of abdomen, 298

of bladder, 298

of head and neck, 301, 302

of kidney, 299

of liver, 299

of pelvis, 298

of rectum, 298

of spleen, 299

of stomach, 299

of testicles, 298

of thorax, 300

of upper extremity, 301

of uterus, 298

of vagina, 298

M

MAJENDIB, foramen of, 313
Malar bones, 58
Malleolus, external, 105

internal, 104
| Malleus, 390
_Mammary artery, internal, 262
| glands, 465

veins, internal, 284 |
Mandible, 62
Marshall, oblique vein of, 283
Masseter muscle, 173
Masseteric nerve, 343
Maxilla, inferior, 62
Maxillary artery, internal, 254

bones, superior, 52

nerves, 341

sinus, 54

veins, internal, 245
Meckel’s ganglion, 341
Median nerve, 360
Mediastinum, 406
Medulla oblongata, 307
Medullary artery, 18, 19
Meibomian artery, 381
Meissner, plexus of, 429
Membrana tympani, 388
Membrane, obturator, 98
Membranes of brain, 3067

of cord, 303

Membranes, synovial, 95
Meningeal arteries, 254, 255
Mesencephalon, 313

Mesenteric artery, inferior, 273

superior, 270
veins, inferior, 295
superior, 295
Metacarpal bones, 92
Metatarsal bones, 109, 110

Midbrain, parts derived from, 313

Mitral valve, 246
Monro, foramen of, 319
Mons veneris, 459

Motor oculi nerve, 337
Mouth, 412

Multifidus spins muscle, 182

Muscle or muscles, 155
of abdomen, 184
abductor hallucis, 237

minimi digiti, 216, 238

pollicis, 215
acecessorius, 180
adductor brevis, 229

hallucis, 237

longus, 228

magnus, 229

minimus, 229

obliquus pollicis, 215

pollicis, 215

transversus, 215

anal, 191

sphincter, external, 191

internal, 191

anconeus, 211
auricular, 169
azygos uvule, 164
biceps femoris, 226

humerus, 202
brachialis anticus, 203
brachioradialis, 210
buccinator, 171
bulbocavernosus, 192
cervicalis ascendens, 180
chondroglossus, 161
ciliary, 384
coccygeus, 192
complexus, 181
compressor urine, 193
constrictor urine, 193

INDEX | 481

‘Muscle or muscles, corrugator

|

constrictors of pharynx, 161, 162
|

coracobrachialis, 202
31

supercilii, 170
cremaster, 187
erureus, 225
deltoideus, 200
diaphragm, 194
digastric, 158
ejaculator urine, 192
epicranius, 169
erector penis, 192
spinze, 179
extensor brevis digitorum, 236
hallucis, 236
pollicis, 213
carpi radialis brevior, 210
longior, 210
ulnaris, 211
coccygeus, 183
communis digitorum, 210
indicis, 212
longus digitorum, 231
pollicis, 212
minimi digiti, 211
ossis metacarpi pollicis, 212
proprius hallucis, 231
triceps, 203
of eyebrows, 170
of eyelids, 170
flexor accessorius,’ 237
brevis digitorum, 237
hallucis, 237
minimi digiti, 46, 238
pollicis, 215
carpi radialis, 205
ulnaris, 207
longus digitorum, 234
hallucis, 235
pollicis, 209
profundus digitorum, 207
sublimis digitorum, 207
gastrocnemius, 233
gemelli, 222
geniohyoglossus, 160
geniohyoideus, 160
gluteus maximus, 221
medius; 221
minimus, 221
gracilis, 229
hyoglossus, 161
iliacus. See Iliopsoas, 220
iliocostalis cervicis, 180

482 INDEX
Muscle or muscles, iliocostalis,; Muscle or muscles, pectoralis
dorsi, 180 major, 196 oe
lumborum, 180 minor, 197

iliopsoas, 220
infracostales, 198
infraspinatus, 200
insertion of, 155
intercostals, 198
interossei of foot, 238
of hand, 216
interspinales, 182
intertransversales, 182

intertransversarii anteriores, 168 |

ischiocavernosus, 179
of larynx, 403
latissimus dorsi, 176
levator (anguli) scapulz, 166
ani, 192
palati, 164
palpebre superioris, 171
levatores costarum, 240
lingualis, 161
longissimus capitis, 181
cervicis, 180
dorsi, 180
longus atlantis, 168
capitis, 168
colli, 166
lumbricales of foot, 237
of hand, 217
masseter, 173
multifidus spins, 182
mylohyoideus, 160
obliquus capitis inferior, 183
superior, 183
externus abdominis, 185
internus abdominis, 187
obturator externus, 223
internus, 222
occipitofrontalis, 169
omohyoideus, 159
opponens minimi digiti, 216
pollicis, 215
orbicularis palpebrarum, 170
of orbit, 171
origin of, 155
palatoglossus, 164
palatopharyngeus, 164
palmaris brevis, 216
longus, 205
pectineus, 228

of perineum, 191
female, 193
male, 191
peroneus brevis, 232
longus, 232
tertius, 232
of pharynx, 161, 162, 163
plantaris, 234
platysma myoides, 156
popliteus, 234
pronator quadratus, 209
teres, 205
psoas magnus, 220
' parvus, 221
pterygoideus externus, 174
internus, 175
pyramidalis, 185
pyriformis, 222
quadratus femoris, 222
lumborum, 220
quadriceps femoris, 224
recti, 172
rectus abdominalis, 184
capitis anticus minor, 168
ateralis, 183
posticus major, 183
minor, 183
femoris, 224
ae ne oe: major and minor,
rotares brevis, 182
longi, 182
sacrolumbalis, 180
sacrospinalis, 179
sartorius, 224 .
scalenus anticus, 166
medius, 166
posticus, 166
semimembranosus, 228
semispinalis, 181
capitis, 181
cervicis, 181 _
dorsi, 181
semitendinosus, 226
serratus magnus, 197
posticus inferior, 178 »
superior, 178
of soft palate, 164

ee

stat tits cee tata

IN DEX

Muscle or muscles, soleus, 233
spinalis cervicis, 181
dorsi, 181
splenius capitis, 178
cervicis (colli), 178
stapedius, 314
sternocleidomastoideus, 158
sternohyoideus, 159
sternothyroideus, 159
styloglossus, 161
stylohyoideus, 159
stylopharyngeus, 163
subclavius, 1 Eek
subcostales, 198
_subcrureus, 226
subscapularis, 201
supinator brevis, 212
longus, 210
supraspinatus, 200
temporalis, 174
tensor palati, 164
tympani, 314

vagine (fascie) femoris, 224

teres major, 201
minor, 201

tibialis anticus, 231
posticus, 234

trachelomastoid, 181

transversalis abdominalis, 187

cervicis, 180
transversus perinei, 192
- trapezius, 176
triangularis sterni, 199
triceps, 203
trochlearis, 171
vastus externus, 225
internus, 225
Musculi pectinati, 243
Musculocutaneous nerve, 360
Musculospiral nerve, 363
Mylohyoid ridge, 63
Mylohyoideus muscle, 156
Myology, 135 -

N

Nargs, posterior, 69, 70
Nasal bones, 60 —
cavities, 69
ducts, 382

(N
iN

N

483

asal fossze, 69
nerves, 340, 397
avicular bone, 108
eck, fascize of, 156
lymphatics of, 301
sympathetic nerves, 374
veins of, 285 -
erves, abducens (sixth), 344
alveolar, 341
ansa hypoglossi, 354, 357
auditory (eighth), 348
auricular (vagus), 351
auricularis magnus, 355
auriculotemporal, 343
buceal, 343
cardiac, 375, 376
cervical, 352
cervical, 355
chorda tympani, 344
ciliary, 341 .
circumflex, 359
coceygeal. See Sacral.
communicans hypoglossi, 354
cranial, 334
crural, anterior, 367
cutaneous, external (lumbar),
367
internal (of arm), 359
lesser internal, 359
dental, inferior, 343
superior, 341
dorsal, 364
epigastric (solar) plexus, 378
esophageal, 353
facial (seventh), 345
frontal, 340
genitocrural, 366
glossopharyngeal (ninth), 348
gluteal, 370
gustatory, 344
hypoglossal (twelfth), 353
iliohypogastric, 366
ilioinguinal, 366
infraorbital, 341

- intercostal, 364

intercostohumeral, 365
interosseous, posterior, 364
Jacobson’s, 349

lacrymal, 340

laryngeal, 352

lingual, 344

484 INDEX

Nerves, lumbar, 365
plexus, 366
lumbosacral cord, 369
masseteric, 343
maxillary, inferior, 342
superior, 341
median, 360
musculocutaneous, 360
musculospiral, 363
nasal, 340
nasopalatine, 342
obturator, 362
accessory, 367
occipital, great, 355
small, 356
oculomotor (third), 337
olfactory (first), 335
ophthalmic, 339
optic (second), 335
orbital, 341
palatine, 342
pars intermedia (nervus inter-
medius), 345, 348
peroneal, 373
petrosal, 345
deep, large, 342, 375
small, 375
external, 345
superficial, large, 342, 345
small, 344, 345
pharyngeal, 349, 352
phrenic, 357
plantar, 373, 374
pneumogastric (tenth), 350
popliteal, external, 373
internal, 371
pterygoid, 343
pudic, 370
radial, 363
sacral and coccygeal, 368
plexus, 369
saphenous, internal, 368
sciatic, great, 371
small, 370
solar plexus, 304
spinal, 354
accessory (eleventh), 353
splanchnic, 377
suboccipital, 355
subscapular, 359
superficialis colli, 355

Nerves, suprascapular, 358
Cee ap of lumbar region,
377
of neck, 374
plexuses, 377
of sacral region, 377
of thorax, 376
temporal, deep, 343
thoracic, 358, 359
tibial, 372, 373
| trifacial (fifth), 338
| trochlear (fourth), 337
/

tympanic, 349
ulnar, 361
Vidian, 341, 342
' Nose, 396
| cartilages of, 396
| Notch, cotyloid, 98
iliosciatic, 93
intercondylar, 101
popliteal, 104
sciatic, great, 93
small, 97
Nymphe, 459

Oo

OBLIQUUS capitis muscles, 183
Obturator artery, 275

crest, 98

externus muscles, 223

fascia, 190

foramen, 98

groove, 98

internus muscle, 222

ligament, 98

membrane, 98

nerves, 367

vein, 294
Occipital artery, 253

bone, 33

lobes, 323

sinus, 288

veins, 285
Occipitoatlantal ligament, 120, 121
Occipitoaxial ligament, 121
Occipitofrontalis muscle, 169
Odontoid ligament, 121
Olecranon fossa, 86
| process, 86

2, ey Oe Oe eee os

INDEX

Olfactory bulb, 335
fila, 335
groove, 51
nerve, 335
tract, 335
Omentum, gastrosplenic, 424
great, 424
lesser, 424, 425
Ophthalmic artery, 256
ganglion, 340
nerve, 339
vein, 289
Gee. minimi digiti muscle,
21
pollicis muscle, 215
Optic chiasm. See Optic nerve.
commissure. See Optic nerve.
foramen, 47
groove, 46
nerves, 335
thalami, 315
Orbicular ligament, 138
Orbital fossa, 65
nerve, 341
Os calcis, 106
magnum, articulation of, 92
pubis, 95
Ossicula, 313
Ossification, 18
Otic ganglion, 344
Ovarian artery, 273
veins, 292
Ovaries, 464

PaxatE, 416
bone, 54
soft, muscles of, 164
Palatine artery, descending, 255
canal, posterior, 55
Palatoglossus muscle, 164
Palatopharyngeus muscle, 164
Palmar fascia, 214
Palmaris brevis muscle, 216
Palpebral ligaments, 170
Pancreas, 441
Pancreatic artery, 270
Parietal bones, 36
lobes, 323

-

485

Parotid glands, 417
Parovarium, 465
Parumbilical veins, 296
Patella, 102
movements of, 151
Pectineus muscle, 228
Pectoralis muscle, major, 196
minor, 197
Peduncles of cerebellum, 310
Pelvis, bones of, 93
differences according to sex, 99
false, 99 ;
fascia of, 190
position of, 99
true, 98
veins of, 294
as a whole, 98
Penis, 452
Perforated space, anterior, 317
posterior, 331.
Pericardium, 241
Perineal arteries, 275
Perineum, central point of, 192
fascize of, 189
muscles of, 191
Peritoneum, 422, 423
Peroneal arteries, 281
nerves, 373
spine, 107
Peroneus brevis muscle, 232
longus muscle, 232
tertius muscle, 232
Pes accessorius. See Eminentia
collateralis.
Petit’s triangle, 187
Petrosal process, 67
sinuses, 288, 289
Phalanges, 110
Pharyngeal arteries, ascending, 253
Pharynx, 416
muscles of, 161, 162, 163
Phrenic artery, 268
nerve, 349, 352
vein, inferior, 292
Pia, 303, 307
Pineal body (epiphysis), 315
Pisiform bone, articulation of, 92
Pituitary body, 318
fossa, 47
Plantar artery, 281
fascia, 235

486

. Plantar ligaments, long, 154
nerves, 373, 374
Plantaris muscle, 234
Platysma myoides muscle, 156
Pleuree, 406
Plexus, brachial, 357
cervical, 355
coccygeal, 368
lumbar, 366
sacral, 369
sympathetic, aortic, 379
“cardiac, 378
carotid, 375
cavernous, 375
celiac, 379
epigastric, 378
gastric, 379
hemorrhoidal, 380
hepatic, 379
hypogastric, 379
mesenteric, inferior, 379
superior, 379
pelvic, 380
phrenic, 378
prostatic, 380
pulmonary, 378
solar, 379
spermatic, 379
splenic, 379
suprarenal, 379
tympanic, 392
uterine, 380
vaginal, 380
vesical, 380
Pneumogastric nerve, 350
Pons varolii, 309
Popliteal artery, 279
lines, 104
nerves, 371, 373
~ notch, 104
space, 279
veins, 293
Popliteus muscle, 234
Portal veins, 295
Postcentral fissure, 323
Postglenoid process, 40
Poupart’s ligament, 186
Precentral fissure, 323
Prepatellar burs, 151
Prevertebral fascia, 158
Process, acromion, 80

INDEX

Process, clinoid, 47, 48
coracoid, 80
coronoid, 63, 86
hamular, 49
olecranon, 86
petrosal, 47
postglenoid, 40
styloid, of fibula, 105
of radius, 91
of ulna, 89
tubarius, 49
uncinate, 51
Profunda arteries, 264, 278
Pronator quadratus muscle, 209
radii teres, 205
Prosencephalon, 315
' Prostate gland, 451
Prostatic plexus veins, 294
_Psoas magnus muscle, 220
| parvus muscle, 221
Pterygoid artery, 255
nerve, 343
| Pterygoideus muscles, 174, 175
| Pterygomaxillary fissure, 66
ligament, 163
Pubofemoral ligament, 145
Pudic artery, internal, 275
nerve, 370
| Pulmonary artery, 246, 247
| veins, 283
| Pylorie artery, 270
| veins, 295 .
| Pyramidalis muscle, 185
Pysiformis muscle, 222

Q

QuapRatus femoris muscle, 222
lumborum muscle, 220
Quadriceps femoris muscle, 224

R
RADIA artery, 265
| fossa, 85
/ nerve, 369
___ veins, 290

| Radiocarpal joints, 139
Radioulnar articulations, 138, 139

oe ee as ee

te tet i el

INDEX

Radius, 90
styloid process of, 91
Rectovesical fascia, 191
Rectum, 435
lymphatics of, 298
Rectus abdominalis muscle, 184
capitis anticus minor, 168
lateralis muscle, 183
posticus muscle, 183
femoris muscle, 224
Reil, island of, 324
Renal artery, 273
veins, 292
Reproductive organs, 451, 459
Retina, 385
Retzius, space of, 450
Rhinencephalon, 324
Rhombencephalon, 307
Rhomboid ligament, 130
Rhomboideus muscle, major, 176

Ridge, pluteal, 101
mylohyoid, 63

Ring, abdominal, external, 186

internal, 188
femoral, 188
Rolando, fissure of, 323
Rotares brevis muscle, 182
longi muscle, 182

Sac, greater peritoneal, 423, 424

lesser peritoneal, 424
Saccule of larynx, 403
Sacral artery, lateral, 274

middle, 269

nerves, 368

plexus, 369

veins, middle, 292
Sacrolumbalis muscle, 180
Sacrosciatic ligaments, 128
Sacrospinalis muscle, 179
Sacrum, 28
Salivary glands, 417
Santorini, cartilage of, 401
Saphenous opening, 219

veins, 293

Sartorius muscle, 224 -

Scalenus anticus, 166
medius, 166
posticus, 166

Seaphoid bone, articulation of, 92,

108
Scapula, 79
Scapular ligaments, 131
Searpa, fascia of, 184
foramina of, 54
triangle of, 277
Schlemm, ligament of, 133
Sciatic artery, 276
nerves, 370, 371
notch, great, 93
small, 97
vein, 294
Sclerotic, coat, 382
Scrotum, 454
Sella turcica, 47
Semen, 458
Semicireular canals, 393
Semilunar bone, 92
cartilages, 148
fold of Douglas, 187
valve, 245, 246
Semimembranosus muscle, 228
Semispinalis capitis muscle, 181
cervicis muscle, 181
dorsi muscle, 181
Semitendinosus muscle, 226
Septum crurale, 220
lucidum, 329
tube, 44
Serratus magnus muscle, 197
posticus muscle, inferior, 178
superior, 178
Sigmoid artery, 273
cavities, 88
flexure, 485
Sinus, cavernous (venous), 288
cranial, 287. See Veins.
maxillary, 54
of Valsalva, 245
Skeleton, 17
Skull as a whole, 64
' base of, 67,68 -
external surface, 65
Soleus muscle, 233
Spermatice artery, 273
cord, 458

487

488 INDEX

Spermatic veins, 292
Sphenoid bone, 46
fissures, 49
Sphenoidal fissure, 66
Sphenomaxillary fissure, 66
fossa, 67
Sphincter muscle, 191
Spinal accessory nerve, 353
canal, 31
column, movements of, 118
cord, 303
columns of, 304
fissures of, 304
nerves, 354
Spinalis cervicis muscle, 181
dorsi muscle, 181
Spine, peroneal, 107
Spinoglenoid ligament, 131
Spiral canal, 394
Splanchnic nerves, 377
Splanchnology, 399
Spleen, 468
lymphatics of, 299
Splenic artery, 270
veins, 295
Splenius capitis muscle, 178
cervicis muscle, 178
Stapes, 390
Stenson, foramina of, 54
Sternoclavicular articulations, 129
Sternocleidomastoideus muscle,
158
Sternohyoideus muscle, 159
Sternothyroid muscle, 159
Sternum, 72
articulations of, 124
body, 73
ensiform, 73
manubrium, 72
Stomach, 427
lymphatics of, 299
Struthers, ligament of, 202
Styloglossus muscle, 161
Stylohyoid ligament, 32
Stylohyoideus muscle, 159
Styloid process of radius, 91
of ulna, 89
Stylomaxillary ligament, 126
Subclavian artery, 258
muscle, 196
veins, 291

Subcrural burse, 151
Subcrureus muscle, 226
Sublingual glands, 418
Submaxillary glands, 418
Suboccipital triangle, 183
Subpubic arch, 99
Subscapular artery, 261
nerve, 359
Subscapularis muscle, 201
Supinator brevis muscle, 212
longus muscle, 210
Supraorbital artery, 257
Suprarenal artery, 273
capsules, 468
veins, 292
Suprascapular artery, 261
nerve, 358
Supraspinatus muscle, 200
Suspensory ligament of penis, 184
Supraspinous ligaments, 117
Sustentaculum tali, 106
Sylvius, fissure of, 322, 323
Sympathetic nervous system, 374
Symphysis pubis, 96
Synovial membranes, 113

T

T2NIA semicircularis, 329
Tarsus, ligaments of, 153
Teeth, 412
Telencephalon, parts included un-
der, 317
Temporal artery, deep, 255
middle, 254
superficial, 254
bones, 39
fossa, 66
lobes, 259
veins, 285
Temporalis muscle, 174
Temporomandibular articulation,
124
Temporomaxillary articulation,124
veins, 285
Tendo Achilles, 234
oculi, 381 :
Tenon, capsule of, 380
Tensor palati muscle, 164
Tentorium cerebelli, 307

————S =

+
——e—EEeE , =

a ti tein ae

INDEX

Testicle, 455
lymphatics of, 298
Thebesii foramina, 243
Thoracic aorta, 267
duct, 296
nerves, 358, 359
Thorax, 71
lymphatics of, 300
sympathetic nerves of, 376
Thymus glands, 467
Thyroid artery, inferior, 261
superior, 52
axis, 261
cartilage, 399
foramen, 98
glands, 466
veins, inferior, 284
Tibia, 103
Tibial arteries, 280
nerves, 372, 373
Tibialis anticus muscle, 231
osticus muscle, 234
Tibiofibular joints, 151, 152
Tongue, 414
Tonsils, 417
Trachea, 406
Trachelomastoid muscle, 181
Tracts of spinal cord, 305
Sai eae abdominalis muscle,
18
cervicis muscle, 180
fascia, 189
Transverse ligaments of knee, 148
sinus, 289
Transversi thoracis muscle, 199
Transversus perinei muscle, 192
Trapezium bone, articulation of,

Trapezius muscle, 176
Trapezoid bone, articulation of, 92

ligament, 130
Treitz, ligament of, 431
Triangle, Petit’s, 187

Searpa’s, 277

suboccipital, 183
Triangularis sterni muscle, 199
Triceps muscles, 203
Tricuspid valve, 244
Trifacial nerve, 338
Trochanter, great, 100

small, 100

489

Trunk, muscle of, 175
Tubarius process, 49
Tuber annulare, 309
cinereum, 317
Tubercle, adductor, 101
carotid, 23
Chassaignac’s, 23
of femur, 100 —
of quadratus, 100
Tuberculum Loweri, 2438
Tuberosity, bicipital, 90
Turbinated bones, inferior, 51, 61
middle, 51
superior, 61
Tympanic artery, 254, 256
plexus, 392
Tympanum, 387

U -
ULNA, 86
Ulnar artery, 266
nerve, 361
veins, 290

Unciform bone, articulation of, 92
Uncinate process, 51
Ureters, 447
Urethra, 453, 460
triangular ligament of, 190
Urinary organs, 443
Uterine artery, 274
Uterus, 461
ligaments of, 463
lymphatics of, 298

V

Vaaina, 461
lymphatics of, 298
Vaginal artery, 274
plexus, 294
Valsalva, sinuses of, 245
Valve, ileocecal, 433
mitral, 246
semilunar, 245, 246
tricuspid, 244
of Vieussens, 311
Vas deferens, 457

490

Vastus externus muscle, 223
internus muscle, 225
Veins, axillary, 290

auricular, posterior, 285

azygos, 291

basilar sinus, 289

basilic, 290

cardiac, 233.

cavernous sinus, 288

cerebellar, 287

cerebral, 286

circular sinus, 288

clitoris, dorsal, 294

cystic, 296

coronary, 283

diploic, 289

emissary veins, 289

facial, 285

femoral, 293

gastric, 295

gluteal, 294

of head and neck, 285

of heart, 283

hemorrhoidal plexus, 294

hepatic, 292

iliac, common, 292
external, 293
internal, 243, 294

iliolumbar, 292

inferior longitudinal sinus, 287

petrosal sinus, 288, 289
innominate, 284
intercostal, superior, 285
internal maxillary, 285
jugular, anterior, 286

external, 285

internal, 286
posterior, external, 286
lateral sinuses, 287
lingual, 286
of lower extremity, 293

lumbar, 291, 292
mammary, internal, 284
median basilic, 290

cephalic, 290
mesenteric, inferior, 295

superior, 295
obturator, 294
occipital, 285

sinus, 288
ophthalmic, 289

|

INDEX

Veins, ovarian, 292 .

parumbilical, 296

of pelvis, 294 —

of penis, 294

- petrosal sinus, 288, 289 —

pharyngeal, 286 .

phrenic, inferior, 292.

portal, 295

prostatic plexus, 294.

pulmonary, 283
pyloric, 295

radial, 290

ranine, 286

renal, 292

sacral, middle, 292

saphenous, 293

sciatic, 294

spermatic, 292

spinal, 291

splenic, 295

straight sinus, 287

subclavian, 291

superior longitudinal sinus, 287

- guprarenal, 292
_ temporal, 285
temporomaxillary, 285
Thebesii, 283
thyroid, inferior, 284
superior, 286
transverse sinus, 289
ulnar, 290
of upper extremity, 290
vaginal plexus, 294
vena cava, inferior, 292
superior, 284
magna Galeni, 287
vesical plexus, 294
vertebrae, 284
Velum interpositum, 328
Ventricles, fourth, 311
of larynx, 403
lateral, of brain, 320
third, 328
Vermis, 310
Vertebree, cervical, 20
characteristics of, 19
lumbar, 26
rotation, 21
atlas, 21
axis, 22
prominens, 23

INDEX

Vertebre, sacral, 28
thoracic or dorsal, 24
Vertebral aponeurosis, 179

artery, 259
column, 19
articulation of, 115
of rotation vertebre, 118
as a whole, 30
. ligaments of bodies of, 115
of lamin of, 117
of processes of, 117
- movements of, 118
veins, 284
Vesalius, foramen of, 50
Vesical arteries, 274
_ plexus, 380
Vesicule seminales, 458
Vestibule, 460
aqueduct of, 44
of ear, 392
Vidian canal, 50
Vieussens’ valvula, 311

Vitreous body, 386
Voeal cords, 403
Vomer, 57

Vulva, 459

WwW

Wits, circle of, 261
Winslow, foramen of, 424
Wirsung, canal of, 443
Wormian bones, 64
Wrisberg, cartilage of, 401
Wrist, articulations of, 139
triangular ligament of, 139

Z

ZINN, ligament of, 172
Zygomatic fossa, 66

491

MA

Little, John. Forsyth

natomy

University of Torento
Library

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