'ion Conipend:

FSSE\TIALS0FAN\T()M\

ChAS. B. NANCRhiJE , M. 13,

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The N<

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925 Walnut Street, Philadelphia.

Third Edition, Revised Complete Vocabulary

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sion of any old work, but it has been written entirely anew
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lary. Besides the ordinary dictionary terms the book contains
a wealth of anatomical and other tables. This matter is
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ESSENTIALS

OF

ANATOMY.

Since the issue of the first volume of the
Saunders Question=Compends,

OVER 175,000 COPIES

of these unrivalled publications have been sold.
This enormous sale is indisputable evidence
of the value of these self-helps to students
and physicians.

SAUNDERS' QUESTION-COMPENDS* No* 3,

ESSENTIALS OF ANATOMY

INCLUDING THE

ANATOMY OF THE VISCERA

ARKANGEU IN THE FORM OF

QUESTIONS AND ANSWERS

PREPARED ESPECIALLY FOR

STUDENTS OF MEDICINE

BY

CHARLES B. NANCREDE, M.D.

Professor of Surgery and of Clinical Surgery in the University of Michigan
Emeritus Professor of General and Orthopedic Surgery, Philadelphia Poly-
clinic; Senior Vice-President of tVie American Surgical Association;
Corresponding Member of the Royal Academy of Medicine,
Rome, Italy ; Member of the American Acad-
emy of Medicine, etc.

SIXTH EDITION, THOROUGHLY REVISED

BY

FRED J. BROCKWAY. M.D.

Assistant Demonstrator of Anatomy, Columbia University, New York

PHILADELPHIA

W. B. SAUNDERS

925 Walnut Street

1899

Copyright, 1899,
By W. 15. SAUNDERS.

C{/n2s

ISII

PRESS OF

ELECTROTVPED BY
WESTCOTT i THOMSON. PHILA. W. B. SAUNDERS. PHILA.

PREFACE TO SIXTH EDITION.

In revising " The Essentials of Anatomy " the general
outline and arrangement of the former editions have been
preserved, some new matter has been added, a few small cuts
have been discarded or replaced by larger ones, descriptions
and statements liave been corrected to accord with recent
works, and many small words have been inserted, adding to
the clearness of description. The revision has been made
with a desire to promote the aims of the book as set forth
by the author in his preface to the first edition.

Fred J. Brockway.

PREFACE TO FIRST EDITION.

The author has endeavored in this little book to embody
only those facts which have appeared to him to be really the
" essentials of anatomy ; " not that he considers it likely that
the student will master every minute detail therein contained,
but he believes that the knowledge gained by a study of this
wr)rk will enal)lo the future practitioner, during the remainder
of his ])rofessional life, to recall such general impressions as
will render intelligible current medical literature, or even the
more elaborate monographs, and will at once suggest ivhere to

11

1 2 PREFACE.

consult his anatomical text-books for such terms or facts as
may have become indistinct through lapse of time.

While this book cannot replace the larger anatomical works,
sufficient descriptive matter has been introduced to enable the
student to refresh his memory of the more numerous facts
learnt in the lecture and dissecting room, or from his " Gray "
or other text-book, differing in this respect-from most of the
works of its class, which are little more than a list of names,
without any distinctive facts connected with them to aid the
student in the difficult task of acquiring a knowledge of a
branch of medical study almost solely dependent upon the
unassisted powers of the memory.

Conciseness, rather than elegance of diction, has been the
aim, so that all words such as the articles " a," " an," " the.''
have been omitted, except where absolutely necessary.

Recognizing that a work of this kind should, as far as pos-
sible, conform to that text-book most commonly used, the last
edition of Gray's Anatomy has been chosen as the chief
authority, although free use has been made of the works of
Quain, Leidy, Bock, Allen, Morris 0)i the JouUs, Starr On
Diseases of Children (dentition). Tomes Dental Anatomy,
Potter, Frey, Holden, Politzer, H. Thompson, Astley Cooper
On the Breast, and original work of one of the author's former
students.

The author would here acknowledge his obligations and
return his thanks to Prof Joseph Leidy, of the University of
Pennsylvania, for the kind permission to reproduce numerous
cuts from the first edition of his Anatomy, and to Dr. F. M.
Varrell for much valuable assistance in the correction of
proof.

Charles B. Nancrede.

CONTENTS.

PAGE

Introduction 17

Bones of the Head 22

The Frontal Bone 22

The Parietal Bones 25

The Occipital Bone ' 27

The Sphenoid Bone 31

The Temporal Bones 35

The Ethmoid Bone 40

The Nasal Bones 43

The Superior Maxillary Bones 43

The Lacrimal Bones 48

The Malar Bones 49

The Palate Bones 50

The Inferior Turbinated Bones 52

The Vomer • 53

The Inferior Maxillary Bone 54

The Sutures and Fontanelles 57

The Cerebral Fossae 58

The Orbital Cavities 61

The Nasal Fossae 66

Bones of the Trunk 69

The Vertebral Colunm 69

The Ilyoid Bone 78

The Thorax 78

The Sternum 80

The Ribs 80

The Pelvic Bones 83

The Pelvis 88

14 CONTENTS.

PAGE

Bones of the Upper Extremity 89

Tlie Arm 95

The Forearm 97

The Hand 102

Bones of the Lower Extremity 106

The Thigh 106

The Patella 109

The Leg 110

The Foot 113

The Articulations 117

The Articulations of the Trunk 119

The Articulations of the Upper Extremity 126

The Articulations of the Lower Extremity 132

Muscles and Fasciae 140

Muscles of the Head 142

Muscles of the Neck 145

Palatal Kegion 148

Vertebral Eegion 149

Muscles of the Back 150

Muscles of the Abdomen 156

Muscles of the Thorax 159

Muscles of the Shoulder and Arm . 161

Muscles of the Forearm 163

Fascia? of the Hand 167

Muscles of the Hand 168

Muscles of the Lower Extremity 169

Muscles of the Leg 175

Fascire of the Foot 178

Muscles of the Foot 179

The Vascular System 181

The Arteries 186

Surgical Anatomy of the Arteries 211

The Veins 213

The Lymphatics 220

The Nervous System 221

The Brain 224

Cranial Topography 237

The Spinal Cord 239

The Cranial Nerves 241

CONTENTS. 15

PAGE

Tlie Spinal Nerves 248

Tlie Thoracic Nerves 252

The Sympathetic System 256

Visceral Anatomy 259

Tlie Digestive Organs * . 259

The Teeth 260

The Mouth 263

The Pharynx 267

The Esophagus 269

The Stomach 270

The Small Intestine 272

The Large Intestine 274

The Liver 276

The Pancreas 283

The Ductless Glands 284

The Spleen 285

The Thyroid Gland 286

The Thymus Gland 287

The Sui:>rarenal Capsules 288

The Abdominal Cavity 289

The Peritoneum 292

Organs of Voice and Resj)iration 295

The Larynx 295

The Trachea and Bronchi 301

The Lungs 303

The l^leurae 308

The Urinary Organs 312

The Kidneys 312

The Ureters 317

The Bladder 318

The Male Urethra 321

Tlie Female Urethra 323

The Male Generative Organs 324

The Penis 325

The Testes and their Coverings 327

The Female Organs of Generation 331

The Vagina 333

The Uterus and its A ppendages 334

The Mammary Glands 339

16 CONTENTS.

PAGE

The Organs of Sense 340

The Skin and its Appendages 340

Tlie Organs of Taste 342

The Organs of Smell 343

The Eye 345

The Appendages of the Eye 359

The Ear 363

The External Ear 303

The Middle Ear, or Tympanum 365

The Internal Ear, or Labyrinth 372

Anatomy of Inguinal Hernia 381

Femoral Hernia 383

The Perineum and Ischiorectal Regions 385

Essentials of Human Anatomy.

Give the derivation and meaning of the term anatomy.

From two (ireek words, av^i, apart, and -ziir^ivj^ to cut, literally
meaning dissection; but it is used to indicate the study of the
physical structure of organized bodies.

How is human anatomy divided ?

Into two great divisions, viz. : 1. General or descriptive anat-
omy, which deals with the separate parts of the human body.
Histology is a part of general anatomy in w^liich the structural
elements are studied, usually with the aid of a microscope. 2.
Surgical or regional anatomy describes the relations which in-
dividual parts — muscles, nerves, arteries, etc. — bear to each
other.

What is osteology ?

A subdivision of general anatomy, describing the number,
form, structure, and uses of the bones.

What is the chemical composition of osseous tissue (bone) ?

About one-third (33.3) is organic or animal matter, resolv-
able into gelatin after prolonged boiling, with traces of chon-
drigen (the proximate principle of cartilage), and two-thirds
inorganic (GO. 7), consisting of calcium phosphate (tribasic)
51.04, calcium carbonate 11.30, calcium fluorid 2, magnesium
phosphate 1.10, and sodium chlorid with traces of sodium
dioxid 1 .20. Either the organic or the inorganic matter may be
removed without affecting the form of the bone ; the former,
by exposure to heat with free access of air, after which slight
force will reduce the bone to powder ; the latter, by steeping
in dilute hyclrochloric acid, which will render a bone as pliable
as a strip of rubl^er. In rickets only about 20 per cent, of
lirae-salts are deposited and 80 per cent, of animal matter.
2 17

18 ESSENTIALS OF HUMAN ANATOMY.

Does an increase of the mineral constituents take place in old
age?

No, although this is a common statement in text-books ;
for wliile e(|ual />«//i>- of young and old bones do show marked
differences in the proportion of earthy and animal constituents,
etjual iccif/ht.s do not, so that the elasticity in youth and the
brittleness in age depend upon the greater sponginess of text-
ure in young bones.

Is bone a homogeneous substance ?

No ; for while the exterior is composed of a comjKicf (hard,
ivory) layer, the inner portions are formed of spongy or cancel-
f'>fis tissue ; the interior of long bones is hollow, forming the
medullary (^marrow) canal. The compact tissue occurs upon
the exterior or in the shaft of long bones where " cross-strain "
is greatest; whereas cancellous tissue enables the articular ends
of the bones to be large for security, yet light, this tissue being
capable of bearing enormous pressure, but incapable of bearing
much •* cross-strain." Probably all solid bone is a definite
compound.

Describe the microscopic structure of bone.

In transverse section, with a low power, a number of holes
will be observed, averaging -^^ inch in diameter, surrounded
by a series of tolerably concentric circles, con.sisting of an
interrupted series of dark spots. With high powers the holes,
called Haversian canals for the passage of vessels, are seen to
be surrounded by a series of concentric rings, termed lamellae,
while the dark spots reveal themselves as cavities in the bone,
called Incmiee, intercommunicating with each other and the cen-
tral Haversian canal by means of delicate radiating lines, called
canalicuU: this aggregation of structures is called an //ra-c/*-
sian system. The lacunae contain bone-corpuscles, processes of
which extend into the canalicnU. As each Haversian system
communicates by its canaliculi with those of its neighbor and
exterior of the bone, all portions of its most compact tissue
and the medullary canal freely intercommunicate and receive
nutrient material. As these systems are circular, they would
leave interspaces where not in contact ; but these gaps are filled
up by layers of bone with tamellst and canaliculi, which por-
tions are called interstitial lamellae. In addition to the concen-

ESSENTIALS OF HUMAN ANATOMY. lU

trie laineUce around the Haversian canals, other lamellae are
found arranged concentrically to the circumference of the
bone, called circumferential or fundamental lameUst. All lamellae
are thin plates of bone ; they are held together by \\\ki l)erforat-
i](g fbcrs of Sltarpei/.

What are the periosteum and the endosteiim ?

The periosteum is a membrane serving as a scaffolding to
enable the blood-vessels to reach all portions of the exterior of
the bone except its articular ends and the points of attachment
of strong tendons. It is composed of two portions : the outer
or fibrous layer is dense and protective ; the inner layer is vas-
cular and contains many osteoblasts, or bone-forming cells, upon
which the growth in thickness of the bone depends.

The term endosteum is applied to the delicate connective-
tissue lining of the medullary and cancellous cavities which
contains numerous bone-forming cells.

Describe the medulla or marrow.

There are two varieties, ^e/fo?c and red: yellow marrow occurs
in adult long bones, and is OG per cent, fat ; red marrow contains
72 per cent, of water and a trace of fat. It is found in all fetal
and infantile bones ; in the adult it is in the short and flat bones,
ends of long bones, vertebra), cranial bones, sternum, and ribs.
Marrow possesses five kinds of cells: fat-cells; marrow-cells
proper, resembling leukocytes ; nucleated red cells ; cells con-
taining red corpuscles ; and giant-cells.

Do bones receive blood only from vessels in the periosteum ?

Xo ; for the medullary tissue of all long bones receives a
good-sized artery (the medullary artery), whichobliquely pene-
trates the compact tissue, after which it divides into two main
branches, one ascending, the other descending, in the medullary
canal ; the veins chiefly emerge through numerous openings
near the articular ends of the bones.

Describe the process of ossification.

There are two methods, viz. : (1) in membrane and subperios-
teolly ; (2) in cortihge. The bones of the vertex of the skull
and those of the face, with few exceptions, are formed in mem-
brane ; the base of the skull and the other bones of the body
and limbs are formed in cartilage. (1) In the former the bone-

20 ESSENTIALS OF HUMAN ANATOMY.

forming cells (^osteoblasts') arrange themselves along the thick
bundles of fibrous tissue which radiate from the center of the
future bone ; by the deposition of lime-salts in these osteo-
blasts the deposit of bone shoots out in needle-like rays to-
ward the circumference. (2) A deposit of bone begins at one
spot of the cartilage, the jjrimari/ cutter. The shaft is formed
from this. Just before ossification commences the cartilage-
cells enlarge and arrange themselves in rows. Lime-salts are
deposited in the matrix between the rows, forming columns
which enclose oblong spaces containing cartilage-cells, called
the primari/ areolae. Now ossification proper commences by
the ingrowth from the periosteum of buds of young connective
tissue covered with bone-forming cells, which, after causing
absorption of the cartilage, become converted into bone.

Of how many bones is the adult human skeleton composed ?

Two hundred, including the os hyoides, but excluding the
teeth, Wormian bones, all sesamoid bones except the patellae,
and the ossicles of the middle ear.

Into what classes are bones divided ?

Long hones, as femur, tibia, etc., about 90 in number; flat,
as those of the vault of the skull, scapula, ribs, patella, about
40; irregular, as the vertebra3, usually symmetrical, about 40;
and short, such as the carpal and tarsal bones, numbering 30.

What are Wormian bones ?

Irregular fragments, developed from supplementary centers,
situated at the junction of two or more cranial sutures, where,
during infancy, a membranous interval existed, viz., a fontan-
elle. From their triangular form they are often called ossa
triqnetra.

What are sesamoid bones ?

Those developed in the substance of tendons, whereby the
muscles obtain additional leverage — /. e. power ; the patella
and pisiform are classed with these bones.

Of what parts do long bones consist, and what are their uses ?

Of a shaft (body, diaphysis), two articular extremities, and
various processes ; they are developed in cartilage, from one
principal and one or more additional (epiphyseal) centers of

ESSENTIALS OF HUMAN ANATOMY. 21

ossification ; they serve as supports and levers for power and
progression.

Where are short and flat bones employed, and why ?

In the carpus and tarsus, where strength with limited motion
is required. The flat bones consist of two layers of compact
tissue with interposed cancellous tissue, called diploe ; they
serve for protection and muscular attachment.

What facts are noted concerning the medullary arteries?

1. Medullary arteries run from the knee and toward the el-
bow. 2. The secondary center from which the artery runs is
the first to appear. 3. The epiphysis first to appear is last to
unite.

How are bony prominences and cavities named ?

Each variety offers an articular and a non-articular division.

Give the names and characteristics of the chief articular
processes.

Head^ a convex smooth projection, with a constriction or
neck beneath; found in freely moving joints.

Condyles^ double projecting processes, may have a constric-
tion or neck — i. e. neck of condyle of jaw.

Mention some of the non-articular processes, with their
meanings.

Trochanters^ short projecting levers near articulations to fa-
cilitate rotation of the bone on its long axis.

Tuhei'osities, roughened, broad prominences.

Tuhrrcles, similar to the above, but small with reference to
the size of the bone.

Spines and spinous processes, more or less pointed projections.

Apophysis^ strictly speaking, any bony process which develops
from the primary center of ossification, commonly used, how-
ever, for any process, even if an epiphysis, after it has coossi-
fied with the mass of the bone. Certain descriptive terms are
used : r^^7/yo.s■, without a fellow ; coracoid^ like a crow's beak ;
mastoid, like a nipple ; rostrum., a beak ; styloid, pen-like ; squa-
mous, like a scale ; vaginal, ensheathing ; clinoid, like a bed.

Name some of the articular cavities of bone.

Cotyloid, wlien they resemble a deep cup ; glenoid, when

22 ESSENTIALS OF HUMAN ANATOMY.

tlicy liave a shallow cup-form ; trochlear, pulley-like ; fdcet,
when smooth, like one of the surfaces of a cut iiem ; siyinoid,
when (-shaped, resembling the old Greek letter lor v"-

What are the principal non-articular cavities called ?

Fossff, shallow depressions ; sinuses, deep cavities, communi-
cating with the exterior by small openings ; c/roovrs^ long, nar-
row depressions ; Jissures, cracks ; iiofchcs, deficiencies of edges
of l)ones ; foramina, holes through bones for transmission of
nerves, etc.

What is a diaphysis ?

The main portion of a bone (shaft in a long bone, body in
an irregular one) between the epqjhi/ses.

What is an epiphysis ?

A supplementary center, usually to provide for growth in
h'iKjfli, developed in cartilage, which remains separated by a
layer of cpipliyscal cartilage until the growth of the bone is
completed, when it co"6ssifies with the eJie/phi/sis, and all further
growth ceases. Epiphyseal centers appear after birth : they
coossify in the inverse order of their appearance, except that
of the lower end of the fibula. This process of coossification
commences about puberty, and the last to unite are those of
the upper end of the tibia and the vertebral bodies — as late as
twenty-five years.

BONES OF THE HEAD.

Name the bones composing the skull.

They are twenty-two in number: eight of which (cranial)
compose the brain-case, viz., one frontal, two parietal, two tem-
poral, one sphenoid, one occipital, and one ethmoid ; fourteen
are facial, two superior maxillary, two malar, two nasal, two
lacrimal, two palatal, two inferior turbinated, one vomer, and
one inferior maxillary, or mandible ; the ethmoid of the cra-
nium also enters largely into the formation of the nasal
cavities.

The Frontal Bone.

Of what parts does this bone consist ?

Of a vertical and a horizontal portion, meeting at an angle
of 60°.

THE FRONTAL BONE.

23

Describe the points on the outer surface of the vertical
portion (Fig. 1).

On each side of the median line are two fronfdl eminences^
between which are the remains of, or the obliterated (jnetoplc)
frontal suture, leaving a slight linear dejiressiou, which, above
the root of the nose, terminates in a rounded, projecting nasal

A^asal process
Fig. 1.— Frontal bone, outer surface (Gray).

eminence (glabella). Extending from this on each side arc two
curved, rounded supprciliari/ ridgrs, situated behind which, be-
tween tliG two tables of the skull, lie the frontal siimsrs (Fig.
2). The junction of the vertical and horizontal portions forms
on each side a curved margin, the supra-orhit<tl arrJi, notched
or perforated toward its m\\(\v part by the supra-orhital iiotr/i,
or foramen, transmitting the artery ;ind nerve of the same
name. Each orbital margin terminates by two stout processes,
calhsd internal anf/ular and external <in(jnl<(r processes. Hcitween
the two inner projects tin; n(fsal process, in the rough, uneven
space, (•all(!d the nasal notrJi ; the under surface of the nasal
process presents a median ridge, nasal spine, between two

24

ESSENTIALS OF HUMAN ANATOMY.

grooves. The inargin of the external angular process ex-
tends upward as the iiifnior temporal ridge (Fig. 1).

Describe the points on the cerebral surface.

In the median line a frordid sulcus (Fig. 2) (for the longi-
tudinal sinus) exists, whose edges coalesce below to form the

iiy\?^<^i^W^^

J || ' Fipn r<iiJ b^tf of No*'
TiiUuJaT rlaU qf Mli-^.uy J J jrrnunj v-iH if IfocrT -'

nut
Na*r ' process

with PerprTL.-i

Fig. 2.— Frontal bone, inner surface (Gray).

frontal cr^.?^, which terminates as a notch, or perhaps complete
foramen csecmn (blind), which when pervious transmits a small
vein.

Describe the horizontal portion.

This consists of two orbital ^^lates of a triangular outline,
separated by a quadrilateral ethmoidal notch (for articulation
with the ethmoid). A shallow lacrimal fossa (for the gland) ex-
ists at the outer part of the orbit, also a trochlear fossa or some-
times a small tuhercle at the anterior inner part for the pulley
of the superior obli((ue muscle. Several half cells are seen
along the margins of the ethmoidal notch, which complete the
ethmoidal cells when the ethmoid is in position, as well as two

THE PARIETAL BONES. 25

grooves^ which are likewise converted into the anterior and^^os-
terior ethmoidal canals^ the former for the nasal nerve and an-
terior ethmoidal vessels, the latter for the posterior ethmoidal
vessels. On each side of the nasal process open the frontal
sinuses (absent in infants), a part of the nasal cavities, into
which each opens by the infiuuUhiihim. The cerebral surfaces
of both vertical and horizontal portions present numerous de-
pressions for the convolutions of the brain, and branching
grooves for the anterior meningeal arteries.

What centers of ossification has this bone ?

Two develop near the orbital arches, in membrane, at the
seventh or eighth fetal week.

With what bones does it articulate ?

With two parietal, the sphenoid, the ethmoid, two nasal, two
superior maxillary, two lacrimal, and two malar— twelve in all.

What muscles arise from it ?

The corrugator supercilii, orbicularis palpebrarum, and tem-
poral on each side.

The Parietal Bones.

Describe a parietal bone ?

It is of a quadrilateral form, convex externally, concave in-
ternally. It presents four borders, four angles, and two sur-
faces. Its upper serrated border forms with its fellow the
sarjittal snture ; the anterior alternately bevelled margin joins
the frontal, forming part of the coronal suture; the inferior
border presents three parts, bevelled in front for the wing of
the sphenoid, next for the squama, then serrated for the mas-
toid ; the posterior serrated border articulates with the occip-
ital (lamhdoid suture). The antero-superior angle is at the
junction of the coronal and sagittal sutures ; the antero-inferior
angle fits under the wing of the sphenoid and internally pre-
sents a groove or canal for the anterior branch of the middle
meningeal artery; the postero-supi^rior angle marks the apex
of the lambdoid suture; the postero-inferior angle articulates
with the mastoid aiid internally shows a groove for part of
the lateral sinus.

The external surface shows near its center the parietal emi-

26

ESSENTIALS OF HUMAN ANATOMY.

uencc or />o.s'.s-. Curving across the middle of the bone are the
upper and Jnin-r frmporal Unca or ridges, for attaelnnent of the
temporal I'ascia and muscle ; and near the posterior superior
angle is often a pdiiital foramni transmitting a small vein to
the superior longitudinal sinus (sometimes a small branch of
the occipital artery).

The inner surface is concave, and its deepest part is the parietal

<^tem.J}o>-ci.l 6o/ue TT^i^

Fig. o. — Left parietal bone, external surface.

fossa. It is marked with numerous smooth digital depressions
for the brain convolutions, with a shallow h«df groove (Fig. 4)
along the superior border for the superior longitudinal sinus,
and several Pacchionian depressions. There are furrows for
arteries and often the opening of the parietal foramen.

How is it developed ?

In membrane, from two centers which coalesce at the emi-
nence, appearing at the fifth to sixth fetal week.

THE OCCIPITAL BONE.

27

Give muscular attachments and articulations.

Temporal muscle : artieuhites with five bones, the opposite
parietal, occipital, temporal, frontal, and sphenoid.

The Occipital Bone.

Of what parts does this bone consist ?

The occipital bone is a curved, trapezoidal plate situated at
the posterior part aud base of the skull. It is convex posteriorly
and concave anteriorly. At birth the bone consists of fonr

Anal"

^,Ani Sup.
Aualc

Ant. LfcT.AneiU

Fig. 4.— Left parietal bone, internal surface (Gray).

pieces. At its lower and anterior part i's tlie foramen mairnum.
I'ehind this is a fahiilar j^oj'fion (squarao-occij»ital ). the upper
part of which may be separate, the iiifrrjxirirfd/ fxttir (bone of
the Tricas) ; the lower part is i<iipr(i-orrip!f(t]. On either side
of the foramen are c/mdijlnr porfionsi (ex-oocipitals), and in front
is tlu; basilar porfion fbnsi-occipital). The bone may be de-
scribed by its fetal divisions or as a whole; in the latter ease
it presents two surfaces, four borders, and four anf:;lcs. The
cxtfrnal surface (V\^. 5) presents midway between the sum-

28

ESSENTIALS OF HUMAN ANATOMY.

iiiit and foramen magnum the external occipitnl protuher-
(tiice (inion) for attachment of the ligamentiim nuchas and
biventer cervicis muscle. Descending from it to the fora-
men is tlie median external occipital crest. The ligamentum
nuchas is attached to it also. Passing outward from the pro-
tuberance on each side to the lateral angle is the s(q)erior curved
line, or superior nuchal line. Internally and above this line

1^ Surfare for Occp f^^.

' oramtn,

M<i.

r.lrs ,
a, J. lig '.

H^^

suptnion

iONSTBlCTOa

Fig. 5.— Occipital bone, outer surface (GrajO-

is often the supreme curved line for attachment of the mid-
dle portion of the occipito-frontalis aponeurosis. Between
these two lines the bone is smooth and dense, the torus trans-
versus (transverse bulge). From the middle of the external
crest a semicircular inferior curved line runs outward on each
side and bends sharply downward to the jugular process. To
the superior curved line is attached internally the trapezius and
externally the occipitalis and sterno-mastoid muscles. Below
this line internally is a large impression for the complexus ;
then come the superior oblique and splenius capitis above and
externally. To the inferior line and depressions below it are
attached the rectus posticus minor internally and the major

THE OCCIPITAL BONE.

29

externally. The foramen mafjnum is an oval aperture, 30 to
35 mm. in its long axis. It transmits the medulla and its mem-
branes, the spinal part of the spinal accessory nerves, vertebral
and spinal arteries, and occipito-axial ligaments. It is broader
behind than in front, and bevelled internally. The condyles are
on either side of the foramen for articulation with the atlas.
They converge in front, are reniform, with smooth, oblong, ar-
ticular surfaces looking downward and outward. Internally is
a depression for the insertion of a check ligament. Behind the
condyle is tha posterior condj/hir fossa . often containing the jjos-
terior condylar foramen for transmission of a vein. External
to the condyle is the jugular process^ presenting ajugidar notch
in front, which forms a part of the jugular fossa. The under
surface presents an eminence (paramastoid), the attachments
of the rectus capitis lateralis muscle and of a lateral ligament ;

S a fie Pi

Fig. 6.— Occipital bone, inner surface (Gray).

the outer surface is a rough, cartilaginous facet for articulation
with th(; tcmponil bone. The basilar process projects forward
and upward in t'nmt of the foramen. It is narrow and thick

30 1:^^SE^T1ALS OF HUMAN ANATOMY.

in front. Below it presents the pharyugaal spine for the attach-
ment of the superior constrictor of the pharynx, and impres-
sions for the rectus capitis anticus major and minor muscles.

Describe the cerebral surface of the bone (Fig. 6).

It is deeply concave, divided into fuar fossae, by a crucial
grooved ridge,, crossing at a prominent iittevnal occipital protuber-
ance ; the two upper fossae lodge the occipital lobes of the cere-
brum, the two lower, the hemispheres of the cerebellum ; the
two lateral and superior grooves lodge, respectively, between
the layers of the tentorium cerebelli and the falx cerebri, the
lateral and part of the superior longitudinal sinuses ; the inferior
groove, or intrmal occipital crest, has attached the Jalx cerebelli,
and lodges in two grooves, the occipittd sinuses. Between the
sinuses is the vermiform fossa. Perforating the base of the
condyle downward and outward is the canalis hypoglossi, some-
times double, ending in the anterior condylar foramen transmit-
ting the hypoglossal nerve, emissary veins, and a branch of the
ascending pharyngeal artery. The upper surfaces of the jugu-
lar processes are deeply grooved for the lateral sinuses. The
upper surface of the basilar process shows the basilar groove
for the medulla, and laterally a half groove for the inferior
petrosal sinus.

Angles.— The superior angle is the apex of the tabular por-
tion; the inferior angle is the end of the basilar process; the
laf( rid angles correspond to the ends of the superior curved

liiu's.

Borders. — The superior borders between the upper and lateral
angles form the lambdoid suture, occipito-parietal ; the upper
part of an inferior border extends from the lateral angle to the
jugular process, masto-occipital ; the lower part articulates with
the petrous portion of the temporal, petro-occipital suture, which
presents posteriorly the Jugular fossa (foramen lacerum pos-
terius).

Attachment of muscles.

Thirteen pairs, as mentioned above.

With what bones does it articulate ?

Two parietal, two temporal, sphenoid, and atlas ; six in all.

THE SPHENOID BONE.

31

What centers of ossification has it ?

Four in the tabular portion ; upper pair in lueuibrane (eighth
fetal week), one for the basilar, and one for each condyloid
portion in cartilage (seventh or eighth fetal week) ; in four
pieces at birth, in the sixth year it forms one bone.

The Sphenoid Bone.

What are its divisions and where is it situated ?

A hody^ two lessi'i- icinys^ two greattr iciiiys, two pttryyoid
plates, two sjmLoiis 2)i'0cesses,a,nd six cUmnd processes ; it is situ-
ated at the base of the cranium, articulating with all the other
cranial bones, and five or seven of the face. Named from a
Greek word meaning ivedge; in the process of development this
is its function. It also somewhat resembles a bat with extended
wings.

Describe the body of the sphenoid.

It is large, cuboidal, hollowed out (in adult) into the sphenoi-
dal sinuses (Fig. 8). ISuperiurly, in front, is a sharp projecting

Uiddlo CUiioid procci • j t c

Fu^tcruir CU.Twid proccst \ _ ^ • '

-~^ -^ V V Croovt Jat

lo'rtf.

lorarmn OpUcu

Ant., 9V S^u.TU»eialFCift

J*t/ravuin JJctu uJu rn

, OuaU

0 S^.iuaivi,

Fig. 7.— Sphenoid bone, superior surface (Gray).

ethmoidal spine for the ethmoid ; behind this, a smooth surface
with a longitudinal cnninence producing two shallow (plf<trf<>ri/
yrooves^ bounding which bc^hind is a transverse optic groove ( Fig.
7), lodging the commissure of the optic nerves, terminating in

32 ESSENTIALS OF HITMAN ANATOMY.

two optic f ova mi iia for the optic nerves and ophthalmic arteries.
Behind the groove is tlie projecting olicari/ procrss^ forming the
anterior boun(hiry of a marked depression, the aclla turcica,
lodging the pituitary gland and circular sinus. On each side,
in front, are two small projecting middle clinoid proca^afs, while
behind is a square-shaped plate, dorsum scJIac, terminating at the
superior angles by the posterior clinoid processes, and to them
are attached portions of the tentorium cerebelli. The sides
of this bony plate are notchi.d for the sixth pair of nerves, and
the superior surface, or dorsnni. with a broad, shallow depres-
sion, slopes obliquely downward and backward, becoming con-
tinuous with the basilar j)ortion of the occipital bone ; it sup-
ports the pons Varolii. A broad cavernous groove for the
carotid artery and cavernous sinus exists on either side of the
body. Posteriorly to the outer side of the groove is the liugida,
and internally the petros(d process. The posterior rough quad-
rilateral surface articulates with the basilar portion of the
occipital bone.

A vertical plate, the sphenoidal crest (Fig. 8), projects from
the anterior surface of the body, forming part of the nasal sep-
tum, having the irregular openings of the sphenoidrd sinuses on
either side (absent in child), which open either into the poste-
rior ethmoidal cells or directly into the nasal cavities. Two
thin curved sphenoidal turhinated bones narrow these orifices
to a round opening at their upper part ; these plates articulate
with the palate and ethmoid bones.

The inferior surface presents in the center the rostrum for
the vomer, having on either side a thin plate, the vaginal
process, articulating with the ala; of the vomer, and the pterijgo-
palatine grooves, which by articulation Avith the sphenoidal
processes of the palate bones are converted into the pterygo-
palatine canals for the pterygo-palatine vessels and pharyngeal
nerve.

Describe the greater wings.

Two strong processes arising from the sides of the body,
curving upward, outward, and backward. The concave c^r^-
br(d surface of each wing forms part of the middle fossa of the
skull, presenting a circular opening at its antero-internal part,
the foramen rotundum for the second branch (superior maxillary)
of the fifth pair of nerves ; a second larger ovoidal foramen,

THE SPHENOID BONE.

33

the foramen ovale (Figs. 7 and 8), transmitting the third (infe-
rior maxillary) division of the same nerve (sometimes the small
petrosal nerve) and small meningeal artery, while piercing the
sharp, pointed, posterior extremity of the wing, or spinous
process^ is seen a short canal (sometimes double), the foramen
.sjjinosum, for the passage of the middle meningeal artery, its
venae comites and the nervus spinosus, a recurrent branch of
the inferior maxillary nerve. Occasionally the foramen Vesalii^
on the inner side of the oval foramen, is present, transmitting
a small vein.

The external surface presents the infratemporal ridge divid-
ing the temporal from the zygomatic fossa ; at its posterior

p-terygoU, Midyt

InterTutl Ttt

ncfmtilu,r /i/foc

Fig. 8.— Sphenoid bone, anterior surface (Gray).

part the spinous process (Fig. 8) gives origin to the tensor tym-
pani muscle and the internal lateral ligament of the lower jaw.
The anterior or orhital surface, smooth, quadrilateral, forming
part of the outer orbital wall, is bounded above by a serrated
edge for articulation with the frontal, below by a rounded bor-
d(;r which enters into the formation of the splicno-mdxillnri/
Jissure ; internally it aids in the formation of the sjihrnoidol
fissure and has a notch at the upper part of the inner border
for a bran(;]i of tin; lacrimal artery ; a small spine at its lower
part, for part of the origin of the external rectus muscle ; ex-

34 ESSENTIALS OF HUMAN ANATOMY.

ternally it presents a serrated articular margin for the malar
bone, and (at times) one or more external orbital forarnina.
The circumference has been described above.

Describe the lesser wings.

These (processes of Ingrassias) two thin, triangular proc-
esses arise from the upper and lateral parts of the body, and
project transversely outward, to terminate internally in the an-
terior clinoid processes (Fig. 7), externally in sharp points. By
their anterior borders they articulate with the orbital plates
of the frontal bone, while by their posterior free margins they
divide the anterior from the middle cerebral fossa. Between
their roots on each side is the optic foramen for the optic nerve
and ophthalmic artery. Each inferior surface forms on either
side the back part of the orbital roof, and the upper boundary
of the sphenoidal fissure, or foramen lacerum anterius. which is
bounded internally b}' the .sphenoid body, and inferiorly by the
orbital margin of the greater wing, externally by the frontal,
transmitting the third, fourth, ophthalmic branch of the fifth,
and sixth nerves, with the ophthalmic veins, filaments from the
cavernous sympathetic plexus, also branches of the lacrimal
and middle meningeal arteries, with a process of the dura
mater.

Describe the pterygoid processes.

These, consisting of an internal and external plate separated
behind by a notch — the ptrrygoid fossa for the internal ptery-
goid muscle — descend on each side perpendicularly from the
junction of the greater wing with the body. At the base of
the internal plate is the scaphoid fossa, giving origin to the
tensor palati muscle, above which is the orifice of the Vidian
canal. Internal to these is the pterygoid tubercle., below that a sul-
cus and a processus tubff: for the Eustachian tube, and then a con-
cave edge for the superior constrictor ; this plate terminates by
a curved hamidar process^ around which plays the tendon of
the tensor palati muscle. The external pterygoid plate has
arising from its outer surface the external pterygoid muscle.
The triangular notch below has fitting into it the tuberosity of
the palate bone.

Name the bones with which the sphenoid articulates.

The other seven cranial bones and five facial, viz., the two

THE TEMPORAL BONES. 35

palate, two malar, and vomer, and sometimes the two superior
maxillae.

By how many centers of ossification is this bone developed ?

By fourteen centers : two for the internal pterygoid plates
in memhmne, two for the greater wings and external pterygoid
plates, two for the lesser wings, two for the anterior part of
the body, two for the sphenoidal turbinated bones, two for the
posterior part of the body, two for the Ungvlse, appearing from
the second fetal month to the third year in cartilage. The
bones completely unite by the twentieth year.

What muscles have their origin from the sphenoid bone?

The temporal, external and internal pterygoids, superior
phar3nigeal constrictor, tensor palati, levator palpebrae, ob-
liquus superior, superior, internal, external, and inferior recti.

The Temporal Bones.

Where are they situated?

At the sides and base of the skull.

What parts does each bone present for examination?

A squamous (scale-like), a mastoid (nipple-like), and 2b petrous
(stony hard) portion.

Describe the squamous portion.

The main portion is an irregularly semicircular, smooth
plate, grooved posteriorly for the deep temporal arteries, con-
vex externally, concave internally, and here grooved for the
middle meningeal artery, with digital drpressions for the cere-
bral convolutions. Posteriorly, a curved ridge (part of tem-
poral) is seen. Springing from its lower part is the long,
twisted, arched zygomatic process., arising by three roots, viz.,
a posterior, forming part of the temporal ridge, one running
directly inward in front of the glenoid fossa, convex, covered
with cartilage, forming the emiiicntia articularis., and a middle,
the outer margin of the glenoid fossa. The obli((uely trans-
verse, glenoid fossa for the condyle of the lower jaw, is divided
into two parts by the Glaserian fssurr (Fig. 0), which trans-
mits the tympanic artery, and lodges the processus gracilis of

36

ESSENTIALS OP^ HUMAN ANATOMY.

the malleus : part of the parotid gland occupies that portion
posterior to the fissure. Parallel to this fissure, in the retiring
angle between the squamous and petrous portions, is the open-
ing of the canal of Huguier for the chorda tympani nerve. At

lUiifot

Fig. 9.— Left temporal bone, outer surface (Gray).

the junction of the articular eminence with the zygomatic
process is the tubercle for the external lateral ligament of the
lower jaw.

Describe the mastoid portion.

This projects, rough, and perforated by numerous foramina,
from the postero-inferior portion of the bone — one foramen,
tlie mastoid, transmits a vein from the lateral sinus and a small
branch of the occipital artery. The interior portion of the
bone contains the mastoid cells, lined with mucous membrane
continuous with that of the tympanum. The conical tip is
termed the mastoid process, upon whose inner side a deep
grooved digastric fossa (Fig. 11) exists for the digastric muscle,
while parallel, but more internal, lies the occipital groove (Fig.
11), lodging the artery of the same name. A deep sigmoid

THE TEMPORAL BONES.

37

fossa (Fig. 10) exists on the inner surface of the mastoid
portion for part of the lateral sinus, in which can be seen
the inner orifice of the mastoid foramen.

p fl, rt ^ fi« /

Diprettiun fci Dura-inattr
Bieattu AudUurin* vrttfpnuj

1 niiuuu for ^uperiar S c^mUiTcuLir C'u^Ji

\^JIiatt^f J'aUopii

L ^'^O^o-nirtq for S-nfaUr.r PctTVtsi^Ntf^
Vevnsiufn fax CtctterLan ganglion
SrUtU passed tiraufA Carotid Canal

Fig. 10.— Left temporal bone, hmer surface (Gray).

Describe the petrous portion.

This is a dense pyramidal mass, wedged in between the
sphenoid and occipital bones, containing the organs of hear-
ing. Its long axis is directed from without inward, forward;
and a little downward. Its apex, three surfaces, and three
borders must be studied. The apex (Fig. 10) lies in the angle
formed by the posterior border of the greater sphenoidal wing
and the basilar process of the occipital, forms the posterior
and external boundary of the foramen lacerum, and presents
the internal orifice of the carotid canal.

The base, its upper half covered by the squamous and mas-
toid portions, presents the oval, expanded orifice of the niratvs
awJiforins exfc/rnvs, its upper margin smooth, but surrounded
for the greater part of its circumference by the rough-edged
(f(»r the cartilage of the external ear), curved plate of bone
called the external auditory process.

38 ESSENTIALS OF HUMAN ANATOMY.

The anterior surface forming the posterior part of the middle
cerebral fossa presents an eminence, eminent ia arcnata (Fig. 10),
near the center, indicating the situation of the vertical semi-
circular canal of the ear ; external to this a depression over the
tympanum, tegmen tympani ; a shallow groove leading back-
ward and outward to an oblique opening, the hiatus Fallopii,
for the great superficial petrosal nerve and the petrosal branch
of the middle meningeal artery ; a smaller groove and opening
external to the latter for the small superficial petrosal nerve ;
the termination of the carotid canal near the apex ; above this
canal a shallow depression for the Gasserian ganglion of the
fifth nerve ; six points of interest.

The posterior surface forms the anterior part of the posterior
cerebral fossa, presents about its center the large orifice of the
short (about four lines) meatus auditorius internus directed out-
ward (closed by a vertical perforated plate, lamina cribrosa),
which transmits the facial and auditory nerves (seventh and
eighth cranial), the auditory artery, and is lined by the dura
mater ; behind the meatus is a small slit leading to the aqiise-
ductus vestibuli, transmitting a small artery and vein, and lodg-
ing a process of the dura mater. Above and between these
points is the suharcuate fossa, which lodges a process of the dura
mater and transmits a small vein.

The inferior (basilar) surface, from apex to base, presents a
rough quadrilateral surface for the origin of the tensor tym-
pani and levator palati muscles ; the circular orifice of the
carotid canal (Fig. 11) ascending vertically, then abruptly
passing horizontally forward and inward for the passage of the
internal carotid artery with its sympathetic nerve plexus; to
the inner side of this — a small, triangular opening, the aquse-
ductus cocJdese, transmitting a vein from the cochlea to the in-
ternal jugular; behind these openings a deep depression, the
Jugular fossa (Fig. 11), which with the jugular notch of the
occipital bone forms the Jugular foramen, transmitting the in-
ferior petrosal and lateral sinuses and between them the ninth,
tenth, and eleventh cranial nerves; a ^maW foramen for Jacob-
sons ne7've, a branch of the glosso-pharyngeal, in front of the
bony ridge separating the carotid canal from the jugular fossa ;
on the outer wall of the jugular fossa a small foramen for
Arnold's nerve ; posterior to the jugular fossa, a square-shaped,
smooth facet for articulation with the jugular process of the

THE TEMPORAL BONES.

39

occipital ; a broad, sheath-like, bony plate extending from the
carotid canal to the mastoid process, the caginal procaas. which,
splitting into two lamime, partially encloses the base of a long,
sharp spine, the styhid process, from which arise the stylo-
pharyngeus, stylo-hyoideus, and stylo-glossus muscles, and the
stylo-hyoid and stylo-maxillary ligaments ; between this process
and the mastoid, a large orifice, the stylo-mastoid foramen, for
the exit of the facial nerve, and the entrance of the stylo-mas-
toid artery ; and, finally, between the vaginal and mastoid proc-

Ciinalspr Elista eJiian tithe
alii/' Tcnsaf-tymf/qnimasclc

LEVATOR PAL

Rcni^h QutuLrilaUral Surface
0£fninq of caroUJ- canal
Canal/for Jacolfon'a nerve
Aijuf'diicrus Corhlcic
Cajuilfor A mold's verve
Ju^ultLr fossa,
\agi na I jfraccss
JSlyJnid p raeess
Sti/lo-mastoi/J, foramen
tTiiytitnr Si' r face
Auricular fisturc

STVLO -PM A^rNOCUS

Fig. 11.— Petrous portion, inferior snrftice (Gray).

esses, the miricidar fissure for the exit of Arnold's nerve, a
branch of the pncumogastric.

At the angle formed by the junction of the petrous and
squamous portions two camds exist, separated by a thin, bony
septum, the septum tnhae, often incorrectly called the processus
ror/df'(trif>nin's, the Upper lodging the tensor tympani muscle,
the lower being the bony Knsfiiehiiin fuhe.

40 ESSENTIALS OF HUMAN ANATOMY.

What additional points of interest do the borders present?

The superior is grooved for the superior petrosal sinus, and
has attached to it the tentorium cerebelli ; the posterior has a
half-groove which, with another on the occipital, accommodates
the inferior petrosal sinus.

From how many centers is this bone developed?

From ten : one for the squamosal and zygoma (in mem-
brane), four for the petrous, two for the mastoid, two for the
styloid, and one for the tympanic plate (all the latter in carti-
lage), from the eighth fetal week to the sixth fetal month —
bone cobssities in the first year, except the styloid process.

With what bones does each temporal articulate?

The occipital, one parietal, sphenoid, one malar, and the
inferior maxillary : five bones.

What muscular attachments has it?

Sipiamoscd, the temporal ; zygoma^ the masseter ; the mastoid
portion and process^ the occipito-frontal, sterno-mastoid, sple-
nius capitis, trachelo-mastoid, digastricus, and retrahens aurem.
Sti/Ioid, the stylo-pharyngeus, stylo-hyoideus, stylo-glossus.
Petrons, the levator palati, tensor tympani, tensor palati, and
stapedius ; fifteen in all.

The Ethmoid Bone.

Of what parts does this bone consist?

Of a horizontal cribriform plate^ (sieve-like), of two lateral

masses^^ of cells depending from this on either side (Fig. 12),
between which lies i\iQ p>erpendicular p)late'^
forming part of the septum of the nose ;
the whole bone is of a cuboidal form.

Describe the cribriform plate.

Springing from the upper surface is the
crista galli^ (cock's-comb), a vertical plate
running from before backward, whose an-
terior border is notched to complete the
bo^„'?,p,i?edo?v"w'." foramen ea-eum of the frontal bone^ Two
deep, longitudinal olfactory grooves, for the
olfactory bulbs, lie on either side, their floors perforated by three
rows of small foramina, for filaments of the olfactory nerves ;

THE ETHMOID BONE.

41

and on each side in front is a small slit for the nasal branch
of the ophthalmic nerve ; the crest gives attachment to the
falx cerebri.

Describe the perpendicular plate (Figs. 12 and 14).

It is thin, usually deflected to one or other side, forms part
of the nasal septum, and has upon each side numerous grooves
and canals to accommodate the olfactory nerve filaments.

Of what are the lateral masses formed? (Figs. 12 and 13).

Of thin-walled cavities, the ctlimoidal cells, three sets, whose
outer limits make the os j^lcinum^, while their inner walls form
part of the nasal fossae ; above they are grooved to form with
grooves on the frontal the two ethmoidal foramina. The upper
outer margins of each mass present a number of half-cells com-

Ufit/t infMurbiiuiteJ 6,

Fig. 13.— Ethmoid bone, outer surface of ri},'ht lateral mass (enlarged) (Gray).

pletely closed in when articulated with the ethmoidal notch of
the frontal bone ; posteriorly are also half-cells completed by
the sphenoidal turbinated and palate bones ; again, in front
and below, the cells are completed by the lacrimal and su-
perior maxillary bones; inferiorly an irregular hook-liko plate
projects, the unciform procena'', which closes in the upper part

42

ESSENTIALS OF HUMAN ANATOMY.

of the orifice of the antrum. A narrow, oblique fissure, the
anpcn'or nasal mfutns, su])divides the inner surface, bounded
above by the thin curved anperior turhuiated hone^, below by
the convex scroll-like middle turbinated hone''] the posterior

Fig. 14.— Perpendicular plate of ethmoid (enlarged), shown by removing the

right lateral mass.

celh open into the upper part of this fissure, the anterior and
middle open into the frontal sinus above, and into the middle
nasal meatus below, by the flexuous infnndibulum. The mid-
dle meatus is bounded above by the middle turbinated bone.

How many centers of ossification has this bone ?

Three : one for each lateral mass (fourth to fifth fetal
month) ; one for the perpendicular and cribriform plates in
cart Huge during the first year ; the ethmoidal cells, completing
the bone, form about the fourth or fifth year.

With how many bones does it articulate?

Fifteen : the sphenoid, two sphenoidal turbinated, frontal,
two nasal, two superior maxillary, two lacrimal, two palate,
two inferior turbinated, and the vomer. No muscles are at-
tached.

THE SUPERIOR MAXILLARY BONES.

43

The Nasal Bones.

Describe them.

They are of oblong form, their outer surfaces concave from
above downward, convex from side to side, marked by many
small arterial furrows and usually presenting at their centers
a single or double venous foramen. Their inner surfaces are

fronVsci oone

/aroouefor ^

Fig. 15 —Right nasal bone, outer Fig. 16.— Left nasal bone, inner

surface. (Gray.) surface.

convex from above downward and concave from side to side,
traversed longitudinally by a groove^ sometimes a canal, for a
branch of the nasal nerve which escapes by a notch about the
middle of the lower thin margin. Each bone presents four
borders.

With what bones does each nasal bone articulate ?

With the frontal, ethmoid, its fellow nasal, and the superior
maxillary. It has no muscular attachments.

How is each developed?

From one center in membrane (eighth fetal week).

The Superior Maxillary Bones.

Describe them.

Th(;y ( acli consist of a hollow body and four processes ; to-
gether they form the whole upper jaw.

Describe the body.

It is ciiboidal in form and hollowed out into a pyramidal
cavity, ihc (tnfrinn of IJiyhniorr. (Fig. IS). Of its four svr-

44

ESSENTIALS OF HUMAN ANATOMY.

faces, the external (facial), directed forward and outward, pre-
sents, just above the incisor teeth, the incisive (myrtiform)
/oss(t (Fig. 17), more externally the larger canine fossa, sepa-
rated from the former by the canine eminence formed by the
socket of the canine tooth ; above this is the infra-orbital fora-
men, giving egress to the infra-orbital artery and nerve ; and
above this surface is the margin of the orbit.

The posterior surface is convex, forms part of the zygomatic
fossa, has about its center several apertures of the posterior
dental canals for the dental vessels and nerves; at its lower
part (especially after the wisdom tooth is formed) is a rounded

Ineisivf fossor

Posterior Hfntal Canah

£laxilloLru Tulerositii,

•"'""■• Micicsiiids.

Fig. 17.— Left superior maxillary bone, outer surface (Gray).

eminence, the maxillar?/ tuherosifi/ (Fig. 17), which articulates
by its rou2:h inner surface with the tuberosity of the palate
bone ; and just above the rough surface is an oblique groove
running down on the inner side, which by the apposition of
the palate bone forms the posterior palatine camtl (Fig. 18).
The superior (orbital plate) surface, thin, smooth, and trian-
gular, forms part of the floor of the orbit, articulates internally
by an irregular margin (from behind forward) with the palate
bone. OS planum of the ethmoid and lacrimal ; externally, by

THE SUPERIOR MAXILLARY BONES.

45

its smooth, rounded edge, it helps to form the spheno-maxilhxry
fissure (sometimes articulating in front with the orbital plate
of the sphenoid) ; anteriorly it forms part of the orbital mar-
gin. At the middle of the outer border of this surface is the
deep infra-orbital groove (Fig. 17), which in front becomes a
canal of the same name, opening by the infra-orbital foramen ;
small canals branching from this pass into the substance of the
anterior wall of the antrum — the anterior and middle dental
canals; at the inner forepart of this orbital surface are a lacri-
mal notch and a minute depression for the origin of the inferior
oblique muscle of the eye.

The internal surface^ unequally divided horizontally into two
parts by the palate process (Fig. 18), forms above this part of

Ethmoid

Infnuif TariinaUd

Palate

i*ii^«d

Ani. N^asal Spilt*

Bristle

paused ihrouak
Ant- palat. Canal

Fig. 18.— Left superior maxillary bone, inner surface ^Gray).

the outer wall of the nasal fossae ; below, a portion of the
mouth. The nasal surface presents a large irregular opening
into the antrum, above which are irregular cellular cavities
closed in, when articulated, by the ethmoid and lacrimal
bones. B(;h)W the opening is the smooth surface forming part
of the inferior meatus of the nose; behind, a ronc/li surface for
the ])ahite bone with a groove passing from above downward
and forward, the posterior palatine, which, closed in by the

4G ESSENTIALS OF HUMAN ANATOMY.

palate bone, forms the posterior palatine canal ; in front, a
deeper vertical groove, which by the apposition of the lacri-
mal and inferior turbinated bones forms the lacrimal canal for
the nasal duct ; and still more anteriorly the well-marked horiz-
ontal, inferior turbinated crest, for the inferior turbinated bone.

Describe the antrum of Highmore (maxillary sinus).

It is triangular, with its apex directed outward formed by the
malar process, its base forming the outer nasal wall, and opens, in
the fresh state, by a small orifice of the size of a probe point into
the middle nasal meatus. In the non-articulated bone there is
a large irregular opening, which is narrowed when articulated
by portions of the palate, ethmoid, inferior turbinated, and
sometimes the lacrimal bones. On its posterior walls are the
posterior dental canals, while its floor presents several conical
prominences, produced by the fangs of the first and second
molar teeth ; sometimes the floor is actually perforated. The
walls are very thin.

Describe the malar process.

It is a rough, triangular eminence, concave on its facial and
zygomatic surfaces, and roughly serrated above for the malar
bone.

Describe the nasal process.

This is thick and triangular, rising upward, inward, and back-
ward, witli an external concave smooth surface, an internal
surface articulating with the frontal above and by a rough sur-
face with the ethmoid ; below this is the transverse ridge-like
superior turbinated crest for the middle turbinated bone. Next
comes a smooth, concave surface, part of the middle nasal
meatus; then the inferior turbinated crest (see antf^-, and,
most inferior of all, the concavity forming part of the inferior
nasal meatus. The anterior border is thin and serrated for
articulation with the nasal bone ; the jxjsterior border is thick,
and grooved for the lacrimal duct, which is directed backward
and a little outicard; where the outer margin of the groove
joins the orbital surface is the lacrimal tvbercle.

Describe the alveolar process.

This is thick and spongy, with eight cavities of varying
depth, that for the canine tooth being deepest, and those for
the molars widest and subdivided.

THE SUPERIOR MAXILLARY BO^'ES.

47

Describe tlie palate process.

It is a horizontal plate (Figs. IS and VJ), thickest in front,
forms most of the roof of the mouth and floor of the nostril ;
has an upper and a lower concave surface. In front, upon the
upper surface, is the upp(;r orifice of the anterujr palatine canal,
which leads to a fossa formed between the two bones, trans-
mitting" the anterior palatine vessels through the forantlna of

J'^or ft rnc'^v
of' St^nsetv^

of ScOJ'pCtt

Post.jjtilaHne (irjittl^

Accessory jjeilatino.

Fig. 19.— The palate and alveolar arch (Gray).

Stensen, the naso-palatine nerves passing through the inter-
maxillary suture by i\\G foramina of Scarpa; upon the under
surface is a longitudinal groove (sometimes a canal), leading
from the posterior palatine canal, for the posterior palatine
vessels and nerve, while in front is seen the lower orifice of
the anterior palatine foana presenting four openings ; the iniier
border is thickened into a ridge on the upper surface, forming
the nasal crest, which rnns higluir in front, called the incisor
crest, and then forms the anterior nasal spine.

4:6

ESSENTIALS OF HUMAN ANATOMY.

How is this bone developed?

Probably by four centers ; it develops so early, immediately
after the clavicle and mandible, that its number of centers is
uncertain. There seem to be the malar j^ortion, orbito-facial,
palatine, and a premaxillary carrying the incisor teeth. The
antrum commences at the fourth fetal month.

With what bones does it articulate?

With the frontal, ethmoid, nasal, malar, lacrimal, inferior
turbinated, palate, vomer, with the other superior maxillary,
and sometimes with the sphenoid.

Give the muscular attachments.

Orbicularis palpebrarum, obliquus oculi inferior, levator
labii superioris alseque nasi, levator labii superioris, levator
anguli oris^ compressor nasi, depressor alae nasi, dilator naris
posterior, masseter, buccinator, internal pterygoid, and orbic-
ularis oris.

The Lacrimal Bones.

What is their shape and where are they situated?

They are two small bones situated at the front part of the

inner wall of the orbit, resembling in form, thinness, and size
u.'ii\rrc7iM a finger-nail, hence called os unguis.

The external orbital surface presents
a vertical ridge giving origin to the
tensor tarsi muscle, in front of which
is a concave longitudinal groove form-
ing part of the lacrimal canal below,
lodging the lacrimal sac above. Be-
low is the hamular process articulating
with the superior maxillary bone, as-
sisting to form the lacrimal canal. A
depressed furrow is seen on the nasal
sin-face corresponding to the ridge ex-
ternally ; the surface in front forming
part of the middle nasal meatus, the
posterior closing in the anterior eth-
This bone also presents foio' horders.

With what bones does it articulate?

With the frontal, ethmoid, superior maxillary, and inferior
turbinated.

In^fi'^-

Fig. 20.— Left lacrimal
bone, external surface (en-
larged) (Gray).

moidal cells

THE MALAR BONES.

49

How is it developed?

From one center in membrane, at the eighth fetal week.
Tlie tensor tarsi muscle of Horner is attached to it.

The Malar Bones.

Describe them.

Two small quadrangular bones placed at the upper outer
part of the face, forming the prominence of the cheek, and
parts of the orbital, temporal, and zygomatic fossa3. The ex-
ternal surface (Fig. 21) is convex, smooth, and perforated by
one or more malar foramina; just below the center the malar
tuberositij gives origin to the two zygomatic muscles. The in-

Busle: f:jzj3ed through /g»'-
i tntpoTO' Mular (h.7iaZs r^^

Fig. 21.— Left malar bone, outer Fig. 22.-Left malar bone, inner

surface. (Gray.) surface.

ternal swface looks into the temporal and zygomatic fossa and
articulates with the superior maxilla (Fig. 22). Superiorly a
thick serrated fro}ifal process articulates with the external an-
gular process of the frontal bone ; a thick, plate-like orbital
process projecting backward, smooth and concave internally,
forms part of the floor and outer w\all of the orbit ; convex
below, it forms part of the temporal fossa. It bounds the
anterior extremity of the spheno-maxillary fissure. Its upper
surface shows the orifices of one or more temporo-malar canals
for filaments of the orbital Ijranch of the superior maxillary
nerve. Externally, projecting ])ackward is the zygomatic process^
articulating with the zygomatic process of the temporal bone
V^y a serrated margin. The maxillari/ process points downward
and articulates wnth the superior maxilla.

50

ESSENTIALS OF HUMAN ANATOMY.

The aiitcro-sHpcrlor border^ smooth and arched, forms the
outer and inferior margin of the orbit ; the ((iitenf-infeilor bor-
der^ roughly bevelled, articulates with the superior maxilla ;
the poatcro-^iiipcrtor border^ like an italic /* is continuous above
with the temporal ridge, below with the up})er border of the
zygoma; the postero-inferior b<jider^ thick and rough, gives
origin to the masseter muscle.

How is it developed?

From three centers, which unite at the fourth fetal month.
It articulates with the frontal, sphenoid, temporal, and superior
maxillary bones.

What muscles arise from it?

The levator labii superioris, zygomaticus major and minor,
masseter, and temporal.

The Palate Bones.

Describe them.

These two bones, situated at the back part of the nasal

Ji£/iiTia. J'ula.ti

%^ Maa^iila ry
Process

Fig. 23.— Left palate bone, internal view (Gray).

fossae, assist in the formation of the floor and outer wall of
the nose, the roof of the mouth, the floor of the orbit, and the
inner wall of the antrum, and aid in forming the spheno-max-
illary and pterygoid foss<T and the spheno-maxillary fissure.

THE PALATE BONES.

51

tS^ihenoitlal /iroeesi.

ylrtieuUrfrort.

Of what parts does each bone consist?

Of a vertical platCi a liorizontal plate^ and three processes,
the pterygoid., .s2)henoidaJ^ and orhital (Figs. !^3 and 24).

Describe the points on the vertical plate.

This thin oblong plate, directed upward and a little inward,
presents internally at its upper part the superior turbinated
crest; lower, a second ridge, the
inferior turhiuated crest., for the
middle and inferior turbinated
bones, between which lies the
groove for the middle nasal
meatus ; below the inferior
crest is another groove., for the
inferior meatus. The posterior
harder articulates with the
pterygoid process of the sphe-
noid ; on the external surface is
a deep groove forming the pos-
terior palatine canal by articu-
lation with the superior max-
illa, transmitting the vessels and
nerve of the same name ; the
upper and back part of this sur-
face helps to form the inner
wall of the spheno-maxillary fossa. The anterior border sends
forward a small lamina of bone opposite the inferior turbi-
nated crest, the tnaxillary process, which narrows the orifice
of the antrum. The posterior border at the lower portion is
pyramidal, forming the pterygoid jrrocess, which is deeply
grooved, forming part of the pterygoid fossa, with a V-shaped
rough margin for articulation with the pterygoid plates.

The superior border., deeply notched by the sphenopalatine
foramen (or notch), presents two processes. The orbital jyrocess
in front articulates anteriirrly with the maxilla, posteriorly with
the sphenoid (its cells here usually opening into the sphenoidal
sinus), internally with the ethmoid, and has a free orbital and
zygomatic surface, the latter looking into the zygomatic fossa,
with a rounded border forming part of tlie spheno-maxillary
fissure ; behind, projecting upward and inward, is the sphenoidal
jrroeess, grooved on its upper surface ])y a ptery go-palatine

'""k'.

Fig. 24.— Left palate bone, posterior
view (Gray).

52 ESSENTIALS OF HUMAN ANATOMY.

groove to help to form the same-named canal ; articulating
here with the sphenoid bone externally and posteriorly with
the pterygoid process, and having an internal concave surface
forming part of the outer wall of the nasal fossa.

Describe the horizontal plate.

This, completing the nasal floor and hard palate, presents on
its inferior surface a transverse rulgc for the tensor palati apo-
neurosis, a deep groove assisting in the formation of the pos-
terior palatine canal ; near this the orifices of one or two acces-
sory posterior palatine canals; an anterior border^ serrated
and bevelled for the palate process of the superior maxilla ; a
smooth concave posterior horder for the attachment of the
soft palate, terminating in the median line by a projection,
which with its fellow on the other bone forms the posterior
nasal spine for the azygos uvuloe muscle ; and an internal
thick horder^ whose upper edge is raised to form with its fellow
a crest articulating with the vomer.

How is this bone developed?

By one center in membrane at the angle of junction of the
two plates (seventh to eighth fetal weekj.

With what bones does it articulate ?

The sphenoid, sphenoidal turbinated, ethmoid, superior max-
illary, inferior turbinated, vomer, and opposite palate.

Give the muscular attachments.

Tensor palati. azygos uvulae, internal pterygoid, and superior
constrictor of the pharynx.

The Inferior Turbinated Bones.

Describe them (Figs. 25 and 26).

They are two thin, scroll-shaped bones, extended horizon-
tally along the outer walls of the nasal fossae, just below the
orifice of the antrum, and are attached to the inferior turbi-
nated crests of the superior maxillary and palate bones, and
present three processes for study : a lacrimal, in front of the
upper border, forming part of the lacrimal canal by its junc-
tion with the lacrimal and superior maxillary bones ; further
back, the ethmoidal j)Tocess, joining the unciform process of the
ethmoid ; and from the lower border of this process the maxil-

THE VOMER.

63

lari/ 2)rocess projects, curving downward and hooking over and
narrowing the orifice of the antrum. The outer surface (from

KiG. 25.— Riofht inferior turbinated bone, Fig. 26.— Right inferior turbinated
internal surface. (Gray.) bone, external surface.

the median plane of the head) is concave ; its inner, convex,
roughened, and grooved for arteries and veins.

Name the bones with which it articulates, and its method
of development.

It articvlatpii with the ethmoid, hicrimal, palate, and supe-
rior maxillary bones ; it is developed by one center in cartilage
(fifth fetal month). No muscles are attached.

The Vomer.

Describe it.

It is a single bone shaped like a plowshare, placed vertically
in the nasal fossae (usually deviated to one side), and forms part

ALX

Fig. 27.— The vomer (Gray).

of the nasal septum. Its siiprrior hordrr is deeply grooved for
the ro.strum of the sphenoid, with lateral loings (ahx)), each of
which meets the vaginal process of the pterygoid process. The

54

ESSENTIALS OF HUMAN ANATOMY.

anterior hoixler is grooved for the vertical plate of the ethmoid
and the nasal septal cartilage. The inffrior harder is received
in the groove formed by the nasal crest of the superior maxil-
lary and palate bones. The pnaterior harder is free, concave,
thick above and thin below, and separates the nasal fossae be-
hind. On each lateral surface is the naso-palatine groove (some-
times a canal) for the nerve of the same name, and also small
furrows for the lodgement of blood-vessels.

Name the bones with which it articulates, and its centers
of ossification.

The sphenoid, ethmoid, both superior maxillary, and both
palate bones. It has two centers (eighth fetal week in mem-
hrane)^ which unite below, but form two laminae above ; ossifi-
cation is not completed until after puberty. No muscles are
attached.

The Inferior Maxillary Bone, or Mandible.

Enumerate its general characteristics.

It consists of a hody, with two rami^ which are surmounted
on either side by a thin triangular coronoid process in front,

Fig 28.— Inferior maxillary bone, outer surface, side view (Gray).

and an articular condyloid process posteriorly ; the constricted
portion beneath the condyle is termed the neck of the condyle ;
the depression separating these two processes is called the sig-
moid notch, crossed by the masseteric vessels and nerve.

THE INFERIOR MAXILLARY BONE.

55

Describe the body of the bone (Fig. 28).

It is Iiorseshoe-shaped, and presents a triangular eminence
in front, the mental jyrocess, with a mental tnl/erde on each side ;
extending upward is a median vertical ridge, the ayinphyak,
marking the junction of the two halves of the bone ; on either
side, just below the roots of the incisor teeth, is the incisor
fossa, giving origin to the levator menti ; and more externally,
below the interval between the two bicuspid teeth, the mental
foramen for the exit of the mental vessels and nerve. Ex-
tending outward from the base of the mental process is a dis-
tinct ridfff. the external oblique line, continuous posteriorly with
the anterior border of the ramus ; to it are attached anteriorly
the depressor labii^nferioris and the depressor anguli oris. The
lower border, just in front of the attachment of the masseter,
is grooved for the facial artery. The internal surface (Fig. 29)

C£NIO-HVO-CLOSSUS
CCKIO-HYOIOeuS

Myh-hycitl Rid^t

B o dij
Fig. 29.— Inferior maxillary bone, inner surface, side view (Gray).

presents an indistinct linear depression, indicating the point of
junction of the two halves of the bone, on eitlicr side of the
center of which are two prominent genial tvhercles, disposed in
pairs, sometimes blended into two, or even one irregular mass,
the upper giving origin to the genio-hyo-glossi, the lower pair
to the genio-hyoidei muscles. Upon each side of these tuber-
cles is the oval stihlingnal fossa for the gland similarly named,
and beneath each is a rough depression for the origin of the

56 ESSENTIALS OF HUMAN ANATOMY.

digastric muscle. Extending obliquely upward and backward
from the sublingual fossa is the internal ohlique line (mylo-
hyoid ridge) for the same-named muscle ; beneath its edge is
the oblong suhmaxillari/ fos.sa for the submaxillary gland ;
above it is the alveolar portion, hollowed into alveoli (sockets)
for sixteen teeth in the adult, ten in the child.

Describe the rami.

These ascending, flattened, quadrilateral plates present in
front the curved coronoid process^ giving attachment to the
temporal muscle by its apex, margins, and inner surface ; next
come the sigmoid notch and the condyle surmounting its nar-
row neck, in front of which is a depression for the tendon of
the external pterygoid muscle, and externarHy a small tubercle
for the external lateral ligament. The articular surface is ob-
long, with its long axis transversely oblique from behind for-
ward and outward, and is convex from behind forward and
from side to side. Upon the inner surface of the coronoid
process commences a longitudinal ridge, with a groove, for the
temporal above, the buccinator muscle below. The outer sur-
face of the ramus has various ridges for the attachment of the
masseter muscle ; its inner surface presents a central oblique
aperture, that of the inferior dental canal (communicating with
each alveolus and terminating at the mental foramen) for the
vessels and nerve ; in front of this opening is a prominent ridge,
terminating behind in a sharp sjyine, or lingnla, for the long in-
ternal lateral ligament ; below the spine is the mi/lo-hyoid
groove for the same-named vessels and nerves ; and behind the
groove is a rongli surface for the internal pterygoid muscle.

At the junction of the posterior and the inferior margins of
the ramus is the angle, marked with rough oblique ridges, ex-
ternally for the masseter, internally for the internal pterygoid
muscle.

With what bones does the inferior maxillary articulate?
With the two temporals.

What ossific centers has it?

It is the second bone of the skeleton to ossify (clavicle first),
and is probably developed by several centers for each lateral
half, chiefly in menihrane, partly in cartilage, which coiissify
about the first year.

THE SUTURES AND FONTANELLES. 57

Compare the forms of the old and the adult jaw.

Ill old age, the alveolar portion being absorbed, the angle
formed by the ramus with the body is very obtuse, and the
dental canal is near the upper surface (important surgically m
operating for neuralgia) ; in adult age the ramus is almost ver-
tical, and the dental canal lies about the middle of the bone.

Give the muscular attachments.

Fifteen pairs : to each ramus, the masseter, temporal, internal
and external pterygoid ; to the mner surface of the hody, the
genio-hyoglossus, genio-hyoid, mylo-hyoid, digastric, and supe-
rior pharyngeal constrictor ; to the outer surface of the body
the levator menti, depressor labii inferioris, depressor anguh
oris, orbicularis oris, platysma myoides, and buccinator.

The Sutures and Fontanelles.

What is a suture ?

A line of interlocking, tooth-like processes, projecting from
the external tables of Ue skull bones (the inner tables are
merely apposed). Sutures are joints of the immovable class,
synarthrosis, and subclass syndesmosis, being united by close
ligaments. They are nineteen in number.

Name those at the vertex.

The interparietal (sagittal), the fronto-parietal (coronal), and
the occipito-parietal (lambdoid).

Name those at the sides.

The spheno-parietal, the squamo-parietal, and the masto-

parietal.

Name those at the base.

One basi-sphenoidal, two petro-occipital. two masto-occipital,
two petro-sphenoidal, and two squamo-sphenoidal. The points
of junction of the sphenoid with the frontal and ethmoid, and
of the frontal with the ethmoid, are not usually described as
sutures.

Which only of the facial sutures has received a name ?

The traasrerse, that extending from one external angular
process of the frontal to the other, joining that bone with the

58 ESSENTIALS OF HUMAN ANATOMY.

malar, sphenoid, ethmoid, lacrimal, superior maxillary, and
nasal bones.

Why does the skull consist of so many pieces?

To admit of continuous growth of the bones at their edges,
pari passu with the growth of the brain ; hence premature co-
ossification of all the sutures results in idiocy. Obliteration
of the sutures occurs at variable periods after maturity.

What are the fontanelles?

They are membranous intervals in the infant's skull, corre-
sponding to the junction of the four angles of the parietal with
the contiguous 'bones. They number six, viz., the anterior, of
lozenge-shape, at the junction of the sagittal and coronal su-
tures, usually closed not later than the second year; the poste-
rior ^ triangular, at the junction of the sagittal and lambdoid
sutures, closed a few months after birth ; and the lateral, one
at the antero-inferior angle, another at the postero-inferior
angle of each parietal bone, which are closed soon after birth.

How are these spaces closed?

By a gradual extension of the ossifying process, or by the
development of additional centers, forming the so-called
Wormian hones.

THE SKULL AS A WHOLE.

The Cerebral Fossae.

Describe the general characteristics of the anterior fossa with
its foramina (Fig. 30).

Formed by the orbital plates of the frontal, the cribriform
plate of the ethmoid and crista galli, the lesser wings and part
of the body of the sphenoid, it is convex on either side and
concave in the median line. The foramina are one median,
the foramen csecinn, which, if pervious, transmits a vein from
the superior longitudinal sinus to the nose ; one slit on each
side of the crista galli for the nasal nerve ; three rows of olfac-
tory foramina on each side for the olfactory filaments; on the
outer side of each olfactory groove the anterior and the poste-
rior ethinoidal foramina, the former transmitting the anterior
ethmoidal artery and the nasal nerve, the latter, the posterior
ethmoidal artery and vein.

THE CEREBRAL FOSS.E.

59

Groove pr Sn^e-r. tmgituJ.SinKs
Graavu3 fjr Aittir MeninijtalA''

Cri^tn GnMi
Slit far A> m/

AnUriMT JEOimoidalS,/;

Or ifiott far OlfaeHmj iieT.f.
^os^-ctiof E Jnnaidul fo

Ethmoidal Sj>ins

Olfactory CramtJ-—

Opfi' Toinmcji-

Ojiti^ OTOove—

Olifanj yraor-

Ajitnriar Clirwid ■pror—

MiJi/U Cluwid jjToe

PoaterloT CUnniJ, j^rroa

Creovt for 6'i 7<in-o

Tor^ Jnctruni mfdium.

Cyifiee of Ca-ratid Canal

Oepttuvtn. fir UaSJeriav, Cavrjlion

Mcatiii Auditin-. Iltternus

Slit fjr I)u.ra-Mafcr

^up. Petrosnl grca-iv

Fnr. laeerum pjiUrius

Anterior CotidylcLd Ti^-n

Aquidu-ct. Veitibuli

"PestcrUir Condyloid Firr.

Mastoid Fai:
Fast. MevXnqeal Groove*.

I

\

Fig. 30.— Base of the skull, inner or cerebral surface (<?ray).

60 ESSENTIALS OF HUMAN ANATOMY.

Give the boundaries and the foramina of the middle fossa.

In front it is bounded by the posterior margins of the lesser
wings of the sphenoid, the anterior clinoid processes, and the
anterior margin of the optic groove ; behind, by the upper bor-
ders of the petrous portions of the temporal bones and dorsum
sella) ; externally by the squamous plates of the temporals and
anterior inferior angles of the parietals. The foramiria are on
each side, the optic for the optic nerve and the ophthalmic
artery. The i^plLenoidal Jissure transmits the third, fourth, three
branches of the ophthahnic division of the fifth and sixth cranial
nerves, and filaments of the sympathetic, the ophthalmic veins,
branches of the lacrimal and middle meningeal arteries with
a process of the dura mater ; immediately behind this, the
foramen rotundum^ for the superior maxillary division of the
fifth cranial nerve ; more posteriorly, x\\q foramen ovale^ for the
inferior maxillary division of the fifth nerve, the small menin-
geal artery, and the small petrosal nerve ; between the two,
internally, the /oramr/i Vesalii (often absent), for a small vein ;
piercing the posterior inferior angle of the greater sphenoidal
wing, the foranwa spiuoHiim^ for the middle meningeal artery,
meningeal veins, nervus spinosus, a recurrent branch from the
inferior maxillary nerve, and the sympathetic branches from
the cavernous plexus ; on the inner side of the oval foramen
the foramen lacernm, (medium,') (filled in below by a plate of
cartilage in the fresh state), for the internal carotid artery,
carotid sympathetic plexus. Vidian nerve, and a small menin-
geal branch from the ascending pharyngeal artery ; on the an-
terior surface of the petrous portion of the temporal is seen
the eminence caused by the superior semicircular canal, emi-
nentia arcuata ; outside this the roof of the middle ear, tegmen
tympani ; the groove leading to the hiafus Fallopii ; a smaller
groove and foramen for the small superficial petrosal nerve ; a
depression for the Gasserian ganglion ; and the orifice of the
carotid canal.

Describe the posterior fossa.

It is deeply concave and formed by the occipital, petrous,
and mastoid portions of the temporal, the posterior inferior
angle of the parietal, and part of the body of the sphenoid.
It presents the meatus auditorins internus for the facial and
auditory nerves and the auditory artery ; the aquaednctus vesti-

THE ORBITAL CAVITIES. 61

huli for a small artery and vein ; the suhai'cuate fossa ; the
foramen lacerum posterius transmitting the glosso-pharyngeal,
pneumogastric, and spinal accessory nerves, the inferior petrosal
and lateral sinuses, and the meningeal branches of the ascend-
ing pharyngeal and occipital arteries ; the mastoid foramen, for
a vein and artery ; i\iQ posterior condyloid foramen (inconstant)
for a vein ; the anterior condyloid foramen for the hypoglossal
nerve, and a meningeal branch from the ascending pharyngeal
artery : and in the floor of the fossa in the median line is the
foramen magnum, accommodating the medulla oblongata and
membranes, the spinal accessory nerves, and the vertebral
arteries.

What additional foramina or openings are found at either
side of the base of the cranium (Fig. 31)?

The orifice of the Eustachian tuhe, admitting air to the mid-
dle ear. The canal for the tensor tympani muscle above the
former, separated from it by the sep>tnm tubse, the posterior
end of which is the processus cochlear if or mis. The posterior
orifice of the Vidian canal, for the Vidian nerve and vessels.
Glaserian fissure for the processus gracilis of the malleus,
and the tympanic branch of the internal maxillary artery.
The orifice of the caned of Huguier, transmitting the chorda
tympani nerve. The canal for Jacohson^s nerve, the tym-
panic branch of the glosso-pharyngeal. The aqusednctvs
cochlese, for a small artery and vein running to and from the
cochlea. The canal for Arnold's nerve, the auricular branch of
the pneumogastric. The auricular fissure, for the exit of Ar-
nold's nerve. The stylo-mastoid foramen, for the exit of the
facial nerve and the entrance of the stylo-mastoid artery.

The anterior and the posterior foramina of the palatal region
have already been sufficiently described, and this region does
not properly belong to the base of the cranium ; while those
opening (externally at the base and upon the face have been
d('scrib(!d sufficiently under the temporal bone and the supe-
rior and inferior maxillary bones.

The Orbital Cavities.

Describe them (Figs. 82 and 33).

Tluey are two (quadrilateral pyramidal cavities, with bases '
outward, their long axes directed from the front inward and

62

ESSENTIALS OF HUMAN ANATOMY.

Ant pnlflintfosm

JTmiismtti Irfe Naso-yalat.-n.
Tmnstiuts Ant yalat rcss
Transmits right, NasofalM.t,.

'fees sory palatitia

Faramina.

PottNtctiil Sjiiiir.
^zvooe uvuix

■ Ha mulit r jt rue

Vjf/tciioiU.proc. cf Palo/te.
-TltTt/gn-faU,ttne C.

TENSOR PALATI
■PJuiTi/Tufeal, Spiru.fvT ivt. CONCTDlCa

-A^utduct. CoihUa-
'FoT. la^etrit. m.jx>rt*riu »
Catuil firrArnolU'l 3h,

Fig. 31.— Base of the skull, external surface (Gray).

THE ORBITAL CAVITIES.

63

backward, in such directions that if prolonged they would
meet about the sella turcica of the sphenoid. Seven bones
contribute to the formation of each, viz . the frontaP, the eth-

FiG. 32.— Anterior region of the skull (Leidj-).

moid", the sphenoid^^, the lacrimaP*, the superior maxillary^,
the palate'^', and the malar"; each communicates with the
ciudiial cavlfij behind by the optic foramen ^^ and the sphenoidal
fissure ^^, with the nasal fosna through the canal of the nasal
duct, and below externally by the spheno-maxillary fissure '^^
with the temporal., zijgoinatic, and sphcno-inaxlUari/ /os.sse.

What bones compose the roof, and what is its form?

Tlie orbital j)late of the frontal anteriorly, the lesser sphe-
noidal wing behind ; it is concave and directed downward and
forward, presenting internally a df'pressiou'^** for the fibro-carti-
laginoiis pnlh;y of tbe superior oblicpie muscle of the eye, and
externally the lacrunal Joasa^' for the lacrimal gland.

64 ESSENTIALS OF HUMAN ANATOMY.

Describe the floor.

Nearly flat, formed chiefly by the orbital plate of the supe-
rior maxillary'^, and to a less extent by the orbital processes
of the malar ^'^ and palate bones; it presents just external to
the lacrimal canal a depression for the inferior oblique muscle ;
externally, the malo-maxlUary suture; near the middle, the
iiifra-orhital groove; and posteriorly, the 'palato-maxillary
suture.

Name the bones forming, and the points of interest upon the
inner wall.

It is flattened, formed by the nasal process of the superior
maxillary, the lacrimal^*, os planum of the ethmoid", and the
sphenoidal body. It presents in front the Jacrhtal groove''^ ^
bounded behind by the lacrhnal crest; further back respec-
tively the lacrimo-ethmoidal and ethmo-sphenoidal sutures.

What forms the outer wall?

The orbital plate of the malar and the greater wing of the
sphenoid, and on it are seen the openings of one or two malar
caiiah^^ and the s])heno-malar suture.

Describe the superior external angle of the orbit.

Posteriorly, the splienoidal fissure (foramen lacerum ante-
rius)^^ for the entrance of the third, fourth, three branches of
the ophthalmic division of the fifth and sixth nerves, and
branches of the middle meningeal artery, a process of the dura
mater, sympathetic nerve filaments, and the exit of the oph-
thalmic veins, and a recurrent branch from the lacrimal artery.
This angle also shows the fronto-malar and the fronto-splienoi-
dal sutures.

What points does the superior internal angle present?

The suture between the lacrimal, ethmoid, and frontal bones ;
between the junction of the two latter bones the anterior eth-
moidal foramen'^ for the anterior ethmoidal vessels and nasal
nerve, and the j^osterior ethmoidal foramen^' for the posterior
ethmoidal vessels.

What points does the inferior external angle present?

The splieno-maxiUari/ Jissure~^ transmitting the infra-orbital
vessels and superior maxillary nerve, the ascending branches

THE ORBITAL CAVITIES.

65

from the spheno-palatinc ganglion, and the orbital branch of
the superior maxillary nerve.

How is the inferior internal angle formed?

By a HufHif, the union of the lacrimal and os planum of the
ethmoid with the superior maxillary and palate bones.

TCNDO OCULt

Ant. Ndscd Sjpine
Incisi've fossa

ii}j^;"y^l, _y:$^0^^^'^^ arccvePr racial af

Fig. 33.— Anterior region of the skull (Gray).

What foramen does the orbital margin present?

Tlie siipr(i-(/r/jif(ii^ at the junction ol" the inner and middle
thirds, transmitting the supra-orbital artery, veins, and nerve.

(j6

ESSENTIALS OF HUMAN ANATOMY.

What foramen opens at the apex of the orbit?

The optlc^''^ between the two roots of the lesser wing of the
sphenoid, transmitting the optic nerve and the ophthalmic
artery.

Mention the nine openings communicating with the orbit.

The optic'", sphenoidal fissure"' (foramen laccrum anterius),
spheno-maxillary fissure'^*', infra-orbital canal', anterior^ and
posterior'^ ethmoidal foramina, malar foramina^", supra-orbital
foramen, and lacrimal canal ■■^° (occasionally, in addition, one or
more external orbital foramina in the wing of the sphenoid).

The Nasal Fossae.

Describe them.

They are two irregular cavities, extending from the base of
the cranium above to the roof of the mouth below, separated
in the median line by a thin osseo-cartilaginous septum, open-

Roof

NouaZ ,
Jfiual S^inc vf frontal £one
BBtaonulFlatc <rf£t}niwid,

Prole poited thrmLgh
Nato-lnehiymal Caiutl

SrittU vatstd through
IrifundCiaium ■

Fh

JLnt. Natal Sjnne

Palate /"roc. of Suri-Max.

FalaCo Broc. cfFalaU

foit. Nasal Spittt

Ant. PalaUiu CaTUtL

Oaur Wall

''Nasa.k Broc. (TfSuptTaX

i4-^ r-tJ.„vu

h-1 Vticifoiml^oe if Eth.

Inf<.Ttor TurbLTia-Udf
Caiatt

Sxijarwr Meatus
Mi/idU. Mtatui
Inferior Keatut

Fig. 34.— Roof, floor, and outer wall of the left nasal fossa (Gray).

ing upon their facial aspect by two large apertures, the anterior
nares, and into the pharynx by the posterior nares. Each fossa
communicates with four sinuses and four cavities (Fig. 34).

THE NASAL FOSSiE. 67

Of what parts is the nasal septum composed ?

In front the crest of the nasal bones and the frontal nasal
spine ; its middle portion, the vertical plate of the ethmoid ;
behind, the rostrum of the sphenoid, the vomer, and the
sphenoidal crest ; below, the crests of the superior maxillary
and palate bones.

What points does the roof of each fossa present ?

In front the dit for the nasal nerve; wwiwevowfi foramina for
the olfactory filaments ; the ^pheno-ethmoidal recess, and most
posteriorly the opening of the sphenoidal sinus.

The floor?

In front the anterior nasal sjmie ; behind this the opening
of the anterior j^cilatine canal and the palate processes of the
superior maxillary and palate bones ; internally, the nasal and
the incisor crest; posteriorly, the posterior nasal spine.

Describe the chief points in the outer wall of each fossa.

This presents three irregular longitudinal passages, formed
by three projecting bony plates, called the siijyerior, middle,
and inferior meatuses.

Describe each meatus.

The superior occupies the posterior third of the wall, lies
between the superior and middle turbinated bones (processes
of the ethmoid), and has opening into it two foramina, the
sphenopalatine posteriorly and the posterior ethmoidal cells in
the front part of the upper wall.

The middle occupies the posterior two-thirds of this wall,
lies between the middle and the inferior turbinated bones, and
has opening into it in front the infnndihidam ; in its center,
the antrum, of Highmore.

The inferior lies between the inferior turbinated bone and
the nasal floor, extends along the whole length of the outer
wall, and has opening into it, in front, the lower orifice of the
canal for the nasal duct (and the anterior palatine canal in the
macerated bone, not in the natural state).

Describe the position and boundaries of the temporal fossa.

Situated at the lateral region of the skull, each fossa is

08 ESSENTIALS OV HUMAN ANATOMY.

marked out upon the Kkull-cap by the femporal ridge^ which
extends in a curved line first upward and backward from the
external angular process of the frontal bone, then downward
behind to form the posterior root of the zygomatic process.
Its aaterior boandtuU'n are the frontal, malar, and greater wing
of the sphenoid ; ahoiyi and bfJiind^ the temporal ridge ; hdow^
the pterygoid or infra-temporal ridge on the greater wing of
the sphenoid ; (ixtji-imllij. the zygomatic arch ; it opens below
into the zygomatic fossa, is filled by the temporal muscle, and
is traversed by grooves for branches of the deep temporal
artery.

Describe the zygomatic fossa, its boundaries and communi-
cating fissures.

It is bounded anteriorly by the tuberosity of the superior
maxilla and the ridge descending from its malar process ; hu-
jferlorhj^ by the infra-temporal ridge of the greater sphenoidal
wing and under part of the squamous plate of the temporal ;
behind, by the posterior border of the pterygoid process ; belov),
by the alveolar border of the superior maxilla ; iidcrnaJh/, by
the external pterygoid plate ; and cxteraallj/. by the ramus of
the lower jaw and the zygoma. The spheno-niaxillary and the
pterijfjo-raaxiUarij fimiiren open into its upper part.

What does it lodge?

1'he internal and the external pterygoid and part of the tem-
poral muscle, the internal maxillary artery, and the inferior
maxillary nerve, and their branches.

Describe the spheno-maxillary fissure.

It runs horizontally, opens into the outer back part of the
orbit, lying between the lower orbital border of the greater
wing of the sphenoid and the outer border of the orbital plate
of the superior maxilla and a small part of the palate bone ;
externally is a small part of the malar, while internally it joins
the pterygo-maxillary fissure at a right angle ; it transmits the
infra-orbital vessels, the superior maxillary nerve, with its or-
bital branch, ascending branches from Meckel's ganglion, and
serves to connect the orbit with the spheno-maxillary, tem-
poral, and zygomatic fossae.

THE VERTEBRAL COLUMN. 69

What are the boundaries of the ptery go-maxillary fissure,
and what passes through it?

It is bounded in front by the maxillary tuberosity ; behind,
by the pterygoid plate of the sphenoid ; descends at right
angles from the inner extremity of the splieno-maxillary fis-
sure, transmits branches of the internal maxillary artery, and
connects the zygomatic and the spheno-maxillary fossae.

Describe the spheno-maxillary fossa.

Situated at the junction of the spheno-maxillary and the
pterygo-maxillary fissures, it is bounded ((hove by the under sur-
face of the body of the sphenoid ; in front by the superior maxil-
lary bone ; behind, by the pterygoid process and the lower part
of the anterior surface of the great wing of the sphenoid ; inter-
nally, by the vertical plate of the palate with its orbital and
sphenoidal processes. In this fossa terminate the i^phenoidal,
spheno-maxillary, and pteri/go-niaxillary Jissures. Four fossae
communicate with it, the orbital, nasal, zygomatic, and the
middle cranial fossae.

How many foramina open into it?

Five (sometimes seven or eight) ; three in the back wall,
viz. above, the foramen rotnndnm ; more internal and inferior,
theVidian ; and lowest and most internal, t\\e ptery go-palatine ;
on the inner wall is seen the spheno-palatine foramen ; below,
the upper orifice of the posterior jndatine canal, and sometimes
two or three accessory posterior palatine canals. This fossa is
thus connected with three fissures, four cavities, and five fora-
mina.

BONES OF THE TRUNK, AXIAL SKELETON.
The Vertebral Column.

How are the vertebrae divided?

Into five regions, viz. cervical (7) ; thoracic (12) ; lumbar (5) ;
sacral (5) ; and coccygeal (4) ; 33 in all.

What are the sacral and coccygeal vertebrae called to dis-
tinguish them from the remaining bones?

p^ahr or fixijd vertebrae, the others being called true or
movable vertebrae.

70

ESSENTIALS OP HUMAN ANATOMY.

What parts are common to all vertebrae?

A hody^; posteriorly on each side -d p>didr'\ supporting two
lamiiide^, which, joining behind, form the neural arch and en-

FiG. 35.— A type-vertebra (Leidy

close the spinal foramen^. The arch supports seven processes,
one spinous^ where the laminae join, two transverse'^, and four
articular^.

Describe a vertebral body.

It is composed of cancellous bone, with a thin, compact layer
externally ; its sides are concave from above downward, while
its upper surface is in the cervical region, concave laterally,
forming a lip at either side, while the lov:er surface is convex
from side to side and concave from before backward, forming an
anterior lip ; in the thoracic region it is flat above and below ;
and in the lumbar region flattened, or slightly concave above
and below. Articular facets and demi-facets for the heads of
the ribs mark the thoracic bodies, neither the lumbar nor the
cervical bodies having these.

Describe the pedicles.

They project backward in all but the cervical vertebrae, where
they are directed obliquely outward. They present vertehral
notches above and below (deepest ahove in the cervical verte-
brae; heloiD in the thoracic and lumbar spine), forming, when
articulated, intervertehral foramina for the exit of the spinal
nerves and the entrance of vessels.

THE VERTEBRAL COLUMN.

71

What are the laminae?

Two broad plates closiiii; in the spinal foramen, roughened

AnteTiorTultTcle of Tram.Froc.

Foramen f„ Vertebral ArT y,
rattevflrTulcrtU ofTrant.Proc

Trantversc Praeest.

S^eriirr Articular Frarean
nfenffrArlicularFriictss

Fig. 36.— Cervical vertebra (Gray).

at their upper margins and at the inferior part of their anterior

surfaces for the ligamenta subflava.

Describe the transverse processes.

They are bifid in the cervical and perforated by the verte-
bral foramen for the vertebral vessels and plexus of nerves ;
thick and strong, with articular facets in the thoracic ; long and
slender in the lumbar; they spring from the junction of the
pedicle and lamina, and also from the side of the body in the
cervical region.

Describe the articular processes.

Two are superior and two inferior, projecting from the junc-
tion of the lamina) and pedicles. The upper pair look h<icl'-
ward and vpicard in the cervical region ; hackirard and out-
inard in the thoracic ; Ixickjrard and iuicnrd slightly in the
lumbar; the lower pair are exactly the reverse of the upper
in each region.

Describe the spinous processes.

Kifid, short, and horizontal in the cervical ; long, triangular,
and din^cted ((blicpicly downward in the thoracic; and thick,
broad, and (luadrilah^ral in tlic; liinil)ar.

72 ESSENTIALS OP HUMAN ANATOMY.

Describe the spinal foramen.

It is largest and triangular in tlie cervical, smallest and round
in the thoracic, medium and triangular in the lumbar.

Name the peculiar vertebrse of each region, and describe
them.

The first cervical, or atlas (Fig. 37) ; the second cervical, or

Traiu.Proct

Forai7ten /or
'ertebral artery

GTOoi/efcr YerceS, Arty
ajid If." Cerv.N£rii£

Spin, pToc.

Fig. 37.— First cervical vertebra or atlas (Gray).

axis ; the seventh cervical, or vertebra prominens ; the first,
tenth, eleventh, and twelfth thoracic, and the fifth lumbar.

The aflaa supports the head, and is formed of two lateral
masses joined by an anterior and a jjosterior arch ; the former

OionUil Pros,

Ajrti>

"j^-ArUe. Surf foi Atlas

-i\-Pody
spin. I'Toe..

1^ T rant. Pro
ZnffT^Tlie.t'roe.

Fig. 38.— Second cervical vertebra or axis (Gray).

presents a facet posteriorly for the odontoid process. Upon
the upper surface of each lateral mass is an articular facet

THE VERTEBRAL COLUMN.

73

looking upward, inward, and backward for the occipital con-
dyles, while the inferior facet looks downward and slightly in-
ward ; a small tubercle represents the spinous process. Devel-
opment is by one center for the anterior arch (first year) ; one
for each lateral mass (seventh fetal week).

The axis (Fig. 38) has surmounting the body the odontoid
process^ with a facet in front for articulation with the atlas,
another behind for the transverse ligament, with a roughened apex
to which are attached the check ligaments ; on each side of the
odontoid, facing upward and outward, are the superior articular
processes. Development is like
other vertebrae, except three
additional centers for the odon-
toid, two appearing at the sixth
fetal month, making six.

The vertebra jyrominens (Fig.
39) is so called because of its
long spinous process, to which
is attached the ligamentum
nuchae. Development is like
other vertebrae, except one ad-
ditional center for the anterior
part of the transverse process.

Fig. 39.— Seventh cervical vertebra,
The peculiar thoracic vertebrae or vertebra prominens (Gray).

(Fig. 41).

The first has an entire facet and a demi-facet on the body ;
the ninth usually has no peculiarity ; the tenth has a demi-
facet on the ped'icle and one facet on the transverse process ;
the eleventh and twelfth have one facet on the pedicle, none
on the transverse processes, the latter also closely resembling
those of a lumbar vertebra.

The fifth lumbar has a markedly wedge-shaped body, with
the base forward.

How are the ordinary vertebrae developed?

By two centers for the body and one for each lamina (sixth
to eighth fetal week) ; at sixteen years one center for the tip of
each transverse, and two for the spinous process ; and at twenty-
one years a plate upon the upper and the lower surfaces of the
body, making ten in all ; the lumbar vertebriX) have two addi-

iSsinam J^LOCfA.

74

ESSENTIALS OF HUMAN ANATOMY.

Dtn'i facet for /irai of Sii

Sa^rricT Artie, troceii /,' \

DemiJacetforluaA Cfjiii

Infer. Artie .Proc.

Fig. 40. — A thoracic vertebra (Gray).

tional centers tipping the superior articular processes ; cobssi-
fication at thirty years.

{An entire facet above.
A demi-facet below.

— A detni-facet above.

(An entire facet.
X No facet on trans, proc,
( ivhich is rudimentary.

(An entire facet.
\ No facet on trans, proc.
(Infer, artic. proc, con-
< ziex and turned out-
(^ 7vard.

Fio. 41.— Peculiar thoracic vertebrae.

Describe the sacrum.

It is composed of five consolidated vertebrae, is of triangular
form with broad base and blunted apex and lateral expanded

THE VERTEBRAL COLUMN.

75

masses or alas ; its anterior surface is concave, its posterior
convex, and with the coccyx it forms the posterior wall of the

Stqjer, Artie. Proc

Fig. 42.— Lumbar vertebra (Graj-).

true pelvis. Its anterior surface (Fig. 43) is marked by four
transverse ridges^ indicating the lines of junction of the seg-

Tromontorii

Fig. 43.— .Sacrum, anterior surface (Gray).

ments ; ei^rht (lutpvior sacral foramina with broad shallow
groovf's for the anterior sacral nerves open on this surface;

76

ESSENTIAL^ OF HUMAN ANATOMY.

the point of junction with the last lumbar vertebra forms the
promontory (sacro-vertebral angle) ; and upon each side are
the alse — the expanded portions of the bone. Posteriorly
(Fig. 44) are three or four median tubercles (rudimentary
spinous processes) ; externally are the laminae, those of the
fifth and sometimes the fourth being deficient ; outside these
is a row of rudimentary articular processes; On each side of
the spine is a broad sacral groove^ lodging the origin of the

upper half of 5th
sacral foramen

Fig. 44.— Sacrum, posterior surface (Gray).

erector spinae muscle; externally are the four j90s/enor mcral
foramma on each side ; at the posterior inferior portion of the
bone are the two cornua — articulating surfaces for the coccyx ;
each lateral surface has on its anterior upper part an auricular
surface for articulation with the ilium ; on each side of the
apex below is a deep notcli^ for the fifth sacral nerve; the hase
resembles the upper surface of a lumbar vertebra, with the
last of which it articulates ; the apex^ directed downward and
forward, has an oval concave articular surface for the coccyx ;
the sacral canal runs the whole length of the bone, triangular
above, small and flattened below, and deficient in its posterior

THE VERTEBRAL COLUMN. 77

wall at the lower part ; it lodges the sacral nerves, and into it
open the anterior and posterior sacral foramina.

What centers of ossification has the sacrum?

Thirty-five or forty, appearing from the eighth fetal week
to the twentieth year, coossification being complete from the
twenty-fifth to the thirtieth year. The bodies have each
three or four centers : each lamina one center ; the lateral
masses three centers each; the lateral surfaces two each.

Give the muscular attachments.

The pyriformis, coccygeus, and iliacus in front ; the gluteus
maximus, latissinms dorsi, multifidus spina), erector spinas, and
sometimes the extensor coccygis behind — seven pairs.

Describe the coccyx (Fig. 45).

It is usually composed of four rudimentary vertebrae, more
or less cobssified ; it forms a triangular bone whose base^ artic-
ulates with the sacral apex. The first piece
presents two cornua'^, projecting upward from
either side of the base for articulation with
the sacral cornua, their junctions completing
the fifth sacral foramina for the posterior
branches of the fifth nerves. The apex^ is
rounded and occasionally bifid or turned to
one side ; rudimentary bodies, transverse and
articular processes may be seen on the first
two segments. Fig. 45.-Coccyx.

Describe its development.

From four centers : one for each segment, the first piece
commencing at birth; second, five to ten years; third, ten to
fifteen years ; fourth, fifteen to twenty years ; coossification
varies as to time and manner.

Give the muscular attachments.

Laterally the coccygeus; behind the gluteus maximus and
extensor coccygeus (inconstant) ; apex, sphincter ani ; in front,
the levator ani.

78

ESSENTIALS OF HUMAN ANATOMY.

The Hyoid Bone.

Describe this bone and its development (Fig. 46).

It coii!5it?ts of a body and two yndtcr and two ItHHer coriiua ;
the greater cor una project backward from the lateral surfaces

Thyro-hyoii.
Slyto-hyoid.
Oiiw-hyoid.
-hyoid.

Gpciio-JiyDid

Steruo-hyoid.

Fig. 46. -Hyoid bone, anterior surface (Gray).

of the body, and have attached to their tubercular ends the
thyro-hyoid ligaments ; the lesser cornna, attached to the junc-
tion between the body and the greater cornua, give attach-
ment by their apices to the stylo-hyoid ligaments ; it is devel-
oped by five centers : one for the body, one for each greater
horn toward the end of fetal life, and one for each lesser horn
some months after birth.

Give the muscular attachments.

The sterno-hyoid, thyro-hyoid, omo-hyoid. digastric, stylo-
hyoid, mylo-hyoid, genio-hyoid, genio-hyo-glossus. chondro-
glossus, hyo-glossus, middle pharyngeal constrictor, and some-
times the lingualis.

The Thorax.

Give its structure, form, and boundaries.

It is conical in form, and its osseo-cartilaginous framework
is formed by the thoracic vertebral bodies behind, the ribs later-
ally, and the costal cartilages and sternum in front ; its base is
formed by the diaphrajim. Through its apex pass the great
cervical vessels, the pneumogastric, phrenic, and sympathetic
nerves, the trachea, esophagus, thoracic duct, and apices of the
lungs covered by pleura.

THE STERNUM.

79

Fig. 47.— Sternum and costal cartila^'t-s. Vm. 18.— Posterior surface of sternum.

(Gray.)

80 ESSENTIALS OF HUMAN ANATOMY.

What are the most important structures this cavity contains ?
The trachea, priuiitive bronchi and lungs, the heart, aorta
and its primary branches, the internal mammary vessels, the
venae cavae, bronchial and azygos veins, the pneumogastric,
phrenic, and splanchnic nerves, the esophagus, thoracic duct,
lymphatic vessels and glands, thymus gland or its remains.

The Sternum.

Describe it (Figs. 47 and 48 j.

The breast-bone consists of three segments, viz. the manu-
brium (handle), the gladiolus (sword), and the ensiform (xi-
phoid) cartilage. Upon the upper border of the manubrium is
the interclavicular notch, upon either side of which is the facet
for the clavicle ; lower, another for the first rib ; below, a demi- -
facet for the second rib.

The gladiolus has a demifacet above for the second rib, an-
other below for the seventh ; and between, facets for the third
fourth, fifth, and sixth ribs.

The ensiform cartilage has a demi-facet above for the carti-
lage of the seventh rib.

How is this bone developed?

By six centers : one for the manubrium, four for the gladi-
olus, one for the ensiform cartilage (fifth fetal month to eigh-
teenth year) ; the three pieces rarely coossify.

What muscles are attached to this bone?

Above, the sterno-cleido-mastoid, the sterno-hyoid, and the
sterno-thyroid ; below, the rectus abdominis, the external and
internal oblique, the transversalis, and the diaphragm ; in front,
the pectoralis major ; behind, the triangularis sterni.

The Ribs.

What is their number, and how are they divided ?

Twelve on each side, seven of which are true, or those artic-
ulating with the sternum by a separate cartilage ; five false,
three of which indirectly articulate through the medium of the
seventh cartilage ; while the two lowest, having their anterior
extremities free, are called floating ribs.

THE RIBS.

81

Of what parts does a rib consist ?

A head, neck, shaft, angle, and tuberosity, except the eleventh
and twelfth ribs.

Describe these parts (Fig. 49).

The liead^ (except the first, eleventh, and twelfth ribs, which
each have only one facet) is divided into two facets by a ridge
for the interarticular ligament. The neck"-^ is flattened, rouyli-
ened upon its upper border for the anterior, and upon its poste-
rior surface for the middle costo-transverse ligaments ; in front

Fig. 49.—^ and B, typical ribs ; C, first rib ; D, twelftli rib.

it is smooth. The tuherosity^ {vih^Qwi in the eleventh and twelfth),
placed at the base of the neck, presents a facet for the trans-
verse process of the next lower vertebra, and a rongh surface
for the posterior costo-transverse ligament. The shaft'' is
twisted on its long axis (except the first and second), ex-
ternally convex, its upper border rounded, its lower grooved^
for the intercostal vessels and nerve, and presents at its ante-
rior extremity an ov(d depression^' for the costal cartilage. The
angle, at a variable distance in front of the tuberosity, is indi-
cated by a rougli line.

How are the ribs developed?

By three centers (except the eleventh and twelfth, two cen-
ters), one each for the head, shaft, and tuberosity (for tlie shaft,
sixth fetal week) ; for the head and tul)erosity (sixteenth to
the twentieth year) ; cotissifies at the twenty -fifth year.

6

82

ESSENTIALS OF HUMAN ANATOMY.

Describe the peculiar ribs.

Tliey are the first, second, eleventh, and twelfth ribs (Figs. 49
and 50).

First rll)% broad, short, flat, one facet on the head, angle ab-
sent ; on the upper surface two parallel grooves, the anterior for

<,^'<i^.

Usually two articular facets

Single articular facet

Single articular facet

Fig. 50. — Peculiar ribs.

the subclavian vein, the posterior for the artery, and between
them a tubercle'^ (Lisfranc's) for the anterior scalene muscle, a
guide to the suhdavian artery.

Second rih, also flattened, the tuberosity and angle nearly
coincide, and presents near its middle a rough eminence for the
attachment of the second and third digitations of the serratus
magnu's and for the scalenus posticus.

THE PELVIC BONES. 83

Tenth rib, usually two facets on the head, hence not peculiar.

Eleventh rib, one facet on the head ; no tuberosity, no neck,
slight angle.

Ticelfth rib'^, one facet on the head ; neither neck, angle, nor
tuberosity.

Describe the costal cartilages.

The costal cartilages (Fig. 47) prolong the ribs to the ster-
num and greatly increase the elasticity of the chest-wall ; they
gain in length to the seventh, and then become shorter ; their
breadth decreases from above down ; their directions vary : the
first descends, the second is horizontal, the third ascends, and
the others (except the last two) descend in the line of the rib
for a short distance and then ascend. Each presents two sur-
faces, two borders, and two extremities ; the anterior surfaces
are convex and give attachment in part to the thoracic and
abdominal muscles ; the j^^^sterirjr surfaces are concave, giving
attachment to the diaphragm and triangularis sterni ; the bor-
ders give attachment to the intercostal muscles and fasciae ; the
outer ends are continued into the osseous tissue of the ribs ;
internally, the cartilages of the true ribs unite w^ith the ster-
num (see page 80) ; those of the first three false ribs (eighth,
ninth, and tenth) become slender and pointed, and unite with
the one above ; the eleventh and twelfth are pointed and free.
The sixth, seventh, and eighth (sometimes the fifth and ninth)
have a series of interchondral articulations by means of a
broad cartilaginous band. All are prone to ossify in old age.

The Pelvic Bones.

What are they?

The ossa innominata, the sacrum, and the coccyx.

Describe the innominate bone (Figs. 51 and 52).

It is formed by the union, about puberty, of three bones,
the ilium, ischium, and pubes (Fig. 51). At their point of
junction is the acetahidum (cotyloid cavity) for the head of
the femur — the pubes forming one-sixth, the ilium three-sixths,
and the ischium two-sixths. A rough central depression at the
bottom of the acetabulum lodges a vascular mass of fat covered
with synovial membrane, while the anterior lower margin is in-
terrupted by the cotyloid notch, bridged across by the trans-

84

ESSENTIALS OF HUMAN ANATOMY.

verse ligament, beneath which pass the nutrient vessels and
ligament uni teres, which latter arises from either side of the
notch externally ; the whole margin has attached to it the

BCKCLLUS SUPCRiOR

SECELCJS WCERJOS

Spine or Ful,$
far Fnupart's LlC/tMCDT

:Tts AooowyritS
rrUMiSALis

Fig. 51. — Right os innomiuatum, external surface (Gray).

cotyloid ligament. Between the pubes and the ischium, on the
anterior surface, is the ohfura tor foramen (thyroid), closed by
the membrane of the same name, except above externally,
where the obturator vessels and nerve escape ; the foramen is

THE PELVIC BONES. 85

a large ovoidal opening in the male, a smaller and triangular
one in the female.

Describe the ilium.

This is the upper expanded portion of the bone (Fig. 51),
presenting along its upper border the crest with its outer
and inner lips, terminating in front by the anterior superior
spinovs process^ giving origin to Poupart's ligament, the sarto-
rius and tensor fasciae femoris muscles, and behind by the
posterior siqyerior spiuous process^ to which are attached part of
the erector spinae muscle and the oblique band of the sacro-
iliac ligament. Below both the anterior and posterior spines
is a process called, respectively, the anterior (for the straight
tendon of the rectus femoris muscle) and j^osterior inferior spin-
ous (for the great sacro-sciatic ligament) ; by these projections
a notch is formed in front and behind, the former giving partial
origin to the sartorius muscle and transmitting the external
cutaneous nerve. Between the posterior inferior spine and the
spine of the ischium is situated the greater sacro-sciatic 7iofch,
giving exit to the pyriformis muscle, the greater and lesser
sciatic, superior and inferior gluteal and pudic nerves, also one
to the obturator internus muscle, and the sciatic, gluteal, and
pudic vessels. About two inches from the posterior superior
spine, passing downward and outward from the crest, is the
svj^erior gluteal line, from the surface back of which arise the
gluteus maximus muscle and a few fibers of the pyriformis ;
about an inch behind the anterior superior spine, passing from
the crest downward and backward to the upper part of the
great sacro-sciatic notch, is the middle gluteal line, the gluteus
medius arising from the space between these two lines ; pass-
ing downward and backward, from the upper part of the ante-
rior inferior spine to the front of the sacro-sciatic notch, is the
inferior gluteal line, between which and the middle arises the
gluteus minimus. Above the acetabulum is a groove for the
reflected tendon of the rectus femoris muscle. The inner sur-
face presents (Fig. 52) in front the iliac fossa for the iliacus
muscle and a broad groove for the psoas-iliacus tendon ; pos-
teriorly is seen — 1, a smooth surface below the ilio-pectineal
line in the true pelvic cavity ; 2, an auricuhtr surface for the
sacrum ; 3, a rough surface for the sacro-iliac ligaments; 4, a
rough surface for the muscles of the back.

S6

ESSENTIALS OF HUMAN ANATOMY.

Describe the ischium.

It consists of a hodj/^ fuherosify, and ranuis, and forms the
lowest part of the innominate bone. The external surface of
the bod^ forms two-sixtlis of the acetabulum ; below this is a

f^ \ : ..■■■■ ^

w ■

^'*/*.' , •' , f — <>" (Lt^— * — llio-ischiadic Junction

Fig. 52.— Right os innominatum, internal surface (Gray).

groovp for the obturator externus tendon ; its inner surface
forms the lateral boundary of the true pelvis ; from the poste-
rior border, below the center, projects the f^pine of the ischium^
above and below which are the greater and lesser sacro-sciatic
notches, the latter giving egress to the obturator internus mus-
cle and ingress to its nerve and to the pudic vessels and nerve.
The lowest portion presents a tuberosity^ with an outer and an

THE PELVIC BONES.

87

inner lip — to the latter being attached the greater sacro-sciatic
ligament ; to the outer is attached the quadratus femoris and
adductor magnus muscles. Passing upward and inward from
the tuberosity to join the ramus of the pubes, and bounding
the obturator foramen in front, is the thin, flattened ascending

ramus.

Describe the pubes.

This bone (also called pectineal) consists of a hody^ a horizon-
tal and a descending ramus. The outer end of the horizontal
ramus forms one-sixth of the acetabulum ; above, a rough dio-
pcctineal eminence indicates the point of junction with the
ilium ; the inner end is the oval symphysis with eight or nine
ridges for attachment of the fibro-cartilage ; the upper triangu-

*^

^

^

*

4

^

$

1^

^

X

^

Fig. 53.— Plan of ihe (levclopment of the os innominatum.

lar surface presents posteriorly the pectineal portion of the ilio-
pectincid line ; the anterior surface presents the cres^ ending
externally in the ]>nhic spine giving attachment to Poupart's
ligament, internally in the angle; below is a groove for the

88 ESSENTIALS OF HUMAN ANATOMY.

obturator vessels and nerve ; the descending ramus, thin and
flat, joins that of the ischium, completing the anterior bound-
ary of the obturator foramen.

How are these bones developed?

By three primary centers (Fig. 53), one for each bone (from
the eighth fetal week) ; and five secondary centers : one for the
crest, one for the tuberosity, one for the anterior inferior spine,
one for the symphysis, and one Y-shaped, joining the three pieces
forming the acetabulum, appearing about puberty ; bone coos-
sifies completely about the twenty-fifth year. (For order of
junction, see Gray.)

What muscular attachments has the innominate bone?

Those of the abdomen, some of the thigh, those of the peri-
neum and pelvic floor.

The Pelvis.

Describe the pelvis.

Formed by the two innominate bones, the sacrum and the
coccyx, all above the ilio-pectineal lines is called \\\e false pelvis^
consisting of the two iliac fossst ; all below, the true pelvis.

Describe the true pelvis.

Its brim., or inlet, somewhat heart-shaped, is formed by the
linea ilio-pectinea at the sides, completed in front by the spine

Fig. 54.— Diameters of the pelvis.

and crest of the pubes, behind by the anterior margin of the
base of the sacrum and promontory of the sacrum. Its aver-

BONES OF THE UPPER EXTREMITY. 89

age diameters in the female are, antero-posterior'^, four inches;
the oblique"'', four and one-half inches; transverse"", five
inches ; its long axis, if extended, would pass from the middle
of the coccyx to the umbilicus ; in the male these measure-
ments are diminished by at least one-half inch.

Describe the cavity.

This is bounded in front by the symphysis pubis, behind by
the concavity of the sacrum and coccyx, on either side by the
broad, smooth inner surface of the ischium and by the lower
part of the ilium, forming a curved canal wider in the middle
than at its outlets, measuring in depth of the symphysis one
and one-half inches, three and one-half inches in the middle
axial line, and four and one-half inches posteriorly, perhaps as
much as five and one-half inches in males.

Describe the lower circumference of the pelvis.

This is called the outlet, is bounded on each side by the tu-
berosity of the ischium, the pubic arch in front and tip of the
coccyx behind. Its diameters, antero-posterior, oblique, and
transverse, measure respectively five, four and one-half, and
four inches, being the reverse of the diameters of the inlet,
explaining the rotation of the fetal head ; in the male the
diameters average three and one-half inches.

What are the chief differences between the male and the
female pelvis?

The strength of the bones, distinctness of the muscular im-
pressions, the depth and narrowness of the cavity, and large
obturator foramina mark the male pelvis ; the lighter bones,
broader iliac fossae, the less-curved sacrum, the wider pubic
arch, and the universally greater diameters distinguish the
female pelvis.

BONES OF THE UPPER EXTREMITY.

Name the bones.

The clavicle, scapula, humerus, radius, ulna, scaphoid, semi-
lunar, cuneiform, pisiform, trapezium, trapezoid, os magnum,
unciform, five metacarpal, and fourteen phalangeal bones.

Describe the clavicle.

It is a long bone, curved like the italic letter/", its outer third

90

ESSENTIALS OF HUMAN ANATOMY.

flattened from above downward, and concave anteriorly ; the
inner two-thirds is cylindrical and convex anteriorly ; it extends
almost horizontally between the sternum and scapula, the two
extremities being respectively termed the sternal and the
acromial.

Describe the chief points presented by the clavicle, com-
mencing at the outer extremity.

The upper surface (Fig. 55) has impressions^ that in front for
the deltoid, that behind for the trapezius ; at the outer end is

Sternal extremity

Acromial exircviity

Fig. 55.— Left clavicle, superior surface (Gray^i.

a facet articulating with the acromial process of the scapula ;
at the po.sterior border, beneath, is the conoid tvhercle (Fig. 56),

Fig. 56.— Left clavicle, inferior surface (Gray).

just above the coracoid process of the scapula, for the conoid
ligament ; extending from the tubercle, forward and outward,
nearly to the outer end of the anterior border is the ohlique
line for the trapezoid ligament ; occasionally at the center of
the anterior border of the outer third is the deltoid tubercle.
The under surface of the middle portion presents the subclavian
groove for the same named muscle — either here or on the pos-
terior surface appears the medullar?/ foramen directed outward ;

BONES OF THE UPPER EXTKEMITY. 91

the inner third of the superior border bears an impression for
the sterno-mastoid muscle (Fig. 55), while the inner half of
the anterior margin has another impression for the pectoralis
major muscle. Beneath the posterior border of the sternal
end is the rhomboid impression^ for the rhomboid or chondro-
clavicular ligament. The sternal end is triangular in form, its
inner surface for articulation with the sternum, this surface
being continuous with a facet beneath, for articulation with
the first costal cartilage.

Give its development.

By two centers : one for the shaft earliest in the body Tthirtieth
day) ; one for the sternal end (eighteenth to twentieth year) ;
uniting about the twenty-fifth year.

Give the muscular attachments.

The sterno-cleido-mastoid, trapezius, pectoralis major, deltoid,
subclavius, sterno-hyoid, and usually the sterno-thyroid ; six or
seven in all.

Describe the scapula.

The shoulder-blade, a large, flat, triangular bone, extends
from the second to the seventh rib or seventh space on the
back and side of the thorax, its posterior margin lying nearly
parallel to and one inch from the spinous processes of the
vertebrae.

The venter (anterior surface) or subscapular fossa is concave,
presents some transversely oblique ridges (Fig. 57) for the
tendinous insertions of the subscapular muscle, and a mar-
ginal surface along the inner border — triangular above and
below, linear between — for the serratus magnus muscle. The
suhscapmlar angle is the transverse depression at its upper part
where the fossa is deepest.

The dorsum (posterior surface) (Fig. 58) is divided by a
prominent bony ridge, the spine^ affording attachment to the
deltoid and trapezius muscles and ending in the acromion
process, into the supra- and inf rasp! nous f(jssf£, for the origin of
similarly named muscles; in the latter is a nutrient foramen.
The lower fossa presents a marrjinal surface, divided by an
ohlique line at the junction of the lower and middle thirds, into
two surfaces, the lower for the teres major, the upper for the

92

ESSENTIALS OF HUMAN ANATOMY.

teres minor muscles ; about the junction of the middle and
upper thirds of this border is a groove for the dorsalis scapulae
vessels. The spine internally presents a triangular surface^
over which plays the ascending part of the trapezius muscle.
The acromion procesfy (summit of the shoulder) is a triangular
flattened process, curving outward, forward, and upward, to

Fig. 57.— Left scapula, anterior surfoce or venter (Gray).

overhang the glenoid fossa ; giving attachment along its outer
margin to the deltoid; its inner margin, the trapezius; by its
a/9e.T, to the coraco-acromial ligament ; and having on its inner
margin, behind the apex, an articular facet (Fig. 57) for the
clavicle.

BONES OF THE UPPER EXTREMITY.

93

Describe the coracoid process of the scapula.

The coracoid process (Figs. 57, 58) (like a crow's beak) rises
by a broad base from the upper part of the neck of the scapula,

,p J*

Ce ra cat'cg j^

Fig. 58.— Left scapula, posterior surface or dorsum (Gray).

curvinjj^ over the inner part of the glenoid cavity. To the
anterior inarfi:;in, near tlie tip, is attached the p(!ctoralis minor
muscle, and from its apex arise the short head of the biceps
and the coraco-brachialis muscle. To the inner side of the

94 ESSENTIALS OF HUMAN ANATOMY.

root is a rough iinpressioii for the conoid ligament, whence
runs obliquely forward and outward on its upper surface a
ridge for the trapezoid ligament. The coraco-acromial liga-
ment is attached externally.

Describe the scapular borders.

The superior border — the shortest — presents at the base of
the coracoid the suprascapular notch (Fig. 58), becoming a
foramen when the transverse ligament is in situ, through which
passes the suprascapular nerve, above wdiich passes the supra-
scapular artery ; from the border just internal to the notch
arises the omo-hyoid muscle. The axillary border — the
thickest — presents just below the glenoid fossa a rough sur-
face for the long head of the triceps muscle, succeeding which
is a longitudinal groove for part of the subscapular muscle.
The vertebral border — the longest — presents an anterior lip for
the serratus magnus muscle, a iwsterior lip for the supra and
infraspinatus muscles, and an interinediate space for the levator
scapula) above, for the rhomboideus minor from the edge of
the triangular apex of the spine, and for the fibrous arch of
the rhomboideus major muscle below.

Give the points of interest connected with the angles.

The superior angle (Fig. 57) affords partial attachment to
the serratus magnus, to the levator scapulae, and supraspi-
natus muscles. The inferior angle (Fig. 58) affords attach-
ment to the teres major muscle, part of the serratus magnus,
and (often) a few fibers of origin of the latissimus dorsi. The
external angle, or head, presents a shallow pyriform glenoid
fossa (Fig. 57) for the head of the humerus, deepened, in the
fresh state, by the glenoid ligament, from the upper part of
which and from the su-praglenoid tubercle the long head of the
biceps flexor cubiti arises. The nech (Fig. 58) is the slightly
depressed surface surrounding the head ; the surgical neck is
well posterior to the head, passing through the suprascapular
notch (Fig. 58).

How is this bone developed?

By seven centers : one for the body (second fetal month) ;
two for the coracoid (one at the first year, one at the fifteenth
to the seventeenth year) ; two for the acromion ; one for the
vertebral border ; one for the inferior angle (all these last,

THE ARM. 95

fifteenth to seventeenth year) ; coossification (twenty-second
to twenty-fifth year). The acromion may not unite with the
spine by bony union, but by a gliding joint with synovial
membrane.

Give the muscular attachments.

The subscapular, supra and infraspinatus, deltoid, trapezius,
omo-hyoid, serratus magnus, levator scapulae, rhomboideus
minor and major, triceps, teres minor and major, biceps, coraco-
brachialis, pectoralis minor, occasionally the latissimus dorsi.

The Arm.

Describe the chief processes and the general characteristics
of the humerus.

This, the only arm bone, articulates above with the scapula,
below with the ulna and radius. The upper extremity, the head
(Fig. 59), nearly hemispherical, facing upward, inward, and
slightly backward, forms with the glenoid fossa of the scapula
the shoulder or scapulo-humeral joint. Best marked supe-
riorly is the constriction called the anatomical neck, indi-
cating the capsular attachment ; external to the head is the
greater tuherouty, with three facets for the supra- and infra-
spinatus and the teres minor muscles ; in front, directed
inward and forward, is the lesmr tiiheroslty for the subscapular
muscle ; commencing between these two projections, and
extending for the upper third of the bone, is the bicipital
grooce, passing obliquely downward and inward, lodging the
long head of the biceps muscle ; into the anterior lip of this
groove is inserted the pectoralis major muscle, into the poste-
rior lip the teres major, and into the floor the latissimus dorsi.
The constriction beneath the tuberosities is called the sur-
gical nech. The sjiaft, cylindrical above, prismoid and flat-
tened below, presents upon the middle of its outer surface a
roughness for the deltoid muscle, and below it, winding from
behind forward and downward, on the back of the bone ( Fig. 60),
is the spiral groove for the musculo-spiral nerve and superior pro-
funda artery, internal and external to which arise the inner and
outer heads of the triceps muscle. At about the center of the
inner bor'ler of the bone is an impression for the coraco-brachialis
muscle, just below which is the medullury canal, directed down-
ward. The lower half of the anterior border, the lower half

y6

ESSENTIALS OF HUMAN ANATOMY.

of the external and the internal sur-
faces, and the internal supracon
dylar ridge give origin to the bra-
chialis anticus. The lower extremity
presents an iiiatr (very proniinent)
and an outer epicotidyle., extending
from each of which, upward on the

iurgical Xt

luruiiTsi tuiftt

>4

>

h"

^.

/.

,>\"' rock It

Fig. 59.— Left humerus, anterior Fig. 60.— Left humerus, pos-

view. (Gray.> terior view.

THE FOREARM. 97

shaft, are the internal and the external supracondylar rldyes ;
from the external ridge and epicondyle arise the external lat-
eral ligament and the extensor diwH sujn n afo r musc\eii ] from the
inner epicondyle and ridge arise the internal lateral ligament and
the flexor muscles and round pronator. Projecting from the
lower front portion of the outer condyle is the radial head
(capitellum), for articulation with the radius ; while internal to
this, extending from the anterior to the posterior surface of the
hone, is the pulley-like trod dear surface for the greater sigmoid
cavity of the ulna. The coronoid fossa in front of the trochlea
receives the coronoid process of the ulna during flexion of the
forearm, while the olecranon fossa, similarly placed behind,
accommodates the tip of the olecranon during extension.

How is the humerus developed?

By seven centers : one for the shaft (fifth fetal week) ; one
for the head (first to second year) ; one (sometimes two; for
the tuberosities (second to third year ; by the fifth year the cen-
ters for the head and the tuberosities have coossified) ; one for
the radial head (second year) ; one for the internal epicondyle
(fifth year) ; one for the trochlea (twelfth year) ; one for the
external epicondyle (thirteenth to fourteenth year). The lower
centers are all cobssified with the shaft by the sixteenth or
seventeenth year except that for the inner epicondyle, which
unites at the eighteenth year, while the head unites at the twen-
tieth year.

Give the muscular attachments.

The supra and infraspinatus, teres minor, subscapularis,
pectoralis major, latissimus dorsi, teres major, deltoid, coraco-
brachialis, brachialis anticus, triceps, subanconeus, pronator
teres, flexor carpi ulnaris. palmaris longus, flexor digitorum
sublimis, flexor carpi radialis. supinator hjngus. extensor carpi
radialis longior and brevior, extensor communis digitorum, ex-
tensor carpi ulnaris, anconeus, supinator brevis, and extensor
minimi digiti (sometimes).

The Forearm.

Describe the ulna.

'j'liis, the inner forearm bone (Fig. (51), longer than the
radius, forms the greater part of the articulation vyith the

7

98

ESSENTIALS OF HUMAN ANATOMY.

F"»9II eiCITORUM
SUBLIMIS

eeffiriorjj ortgCn-
OF run* laNcui poliic

RaJiaZ Orurtft

FLCXOR DICITORUM
SUBLIMIS

Styloid J'rocna

urmATOR LSMOUC

'OLiieis
Groove fur extensor
brevi» poUicia

StyUcJ Ifrtent

Fig. 61.— Bones of the left forearm, anterior surface (Gray).

THE FOREARM. 99

humerus, while it is excluded from the wrist-joint by the inter-
articular fibro-cartilage. Its upper extremity forms the point
of the elbow. The olecranon process presents upon its anterior
part a saddle-shaped articular surface which, with its con-
tinuation on the coronoid process, is the greater sigmoid cavity
for the trochlea of the humerus ; continuous with this upon
the outer side is the lesser sigmoid cavity for the head of the
radius; to the superior surface is attached the triceps tendon,
and the apex is accommodated by the olecranon fossa of the
humerus during extension. Projecting forward below the ole-
cranon is the coronoid process, fitting into the same named
fossa of the humerus during flexion, its upper surface forming
part of the greater sigmoid cavity ; it presents, where it joins
the shaft, a tubercle for the oblique ligament and a rough im-
jwcssion for the brachialis anticus muscle above and internally.
At the front is a small eminence for the flexor sublimis digi-
torum, whence descends a ridge for the pronator teres. The
shaft, large and prismatic above, smaller and rounded below,
has on its anterior surface the medullary foramen, directed
upward, and gives attachment to the flexor profundus digito-
rum and pronator quadratus muscles ; the bdernal surface gives
attachment to the flexor profundus ; the posterior surface (Fig.
62) gives attachment from above downward to the anconeus,
supinator brevis, extensor ossis metacarpi pollicis, extensor
longus pollicis, and extensor indicis. The jjosterior border gives
attachment by a common aponeurosis to the flexor and exten-
sor carpi ulnaris and to the flexor profundus digitorum. The
external sharp border aflbrds attachment to the interosseous
ligament. The lower carpal extremity, or head, articulates by
its outer surface with the sigmoid cavity of the radius, and by
its lower with the triangular fibro-cartilage ; projecting inter-
nally and behind is the styloid proces^i, to whose apex is attached
the internal lateral ligament, to a depression at its base the
fibro-cartilage ; upon the posterior surface is a groove for the
tendon of the extensor carpi ulnaris.

How is this bone developed?

By three centers : one for the shaft (eighth fetal week) ;
one for the head (fourth year) ; one for the olecranon (tenth
year, joining the shaft at the sixteenth year) ; head coossified
with the shaft by the twentieth year.

100 ESSENTIALS OF HUMAN ANATOMY.

Give the muscular attachments.

The triceps, anconeus, flexor carpi ulnaris, brachialis anticus,
pronator teres, flexor siiblimis and profundus digitorum, flexor
longus pollicis (very often), pronator quadratus, flexor and ex-
tensor carpi ulnaris, supinator brevis, extensor ossis metacarpi
and longus pollicis, and extensor indicis.

Describe the radius.

Shorter than the ulna, situated upon the outer side of the
forearm, with a small upper extremity, forming only a small
part of the elbow-joint, its lower end is large, forming the chief
part of the wrist-joint. It is slightly curved and of a pris-
matic form. The head (upper extremity) (Fig. 61) is cylin-
drical, with a slightly cupped upper surface, articulating with
the radial head of the humerus, by its side* with the lesser
sigmoid cavity of the ulna and the orbicular ligament by which
it is embraced ; the constriction beneath the head is the neck ;
below and to the inner side is the tvherosiiij. rough toward its
posterior margin for the biceps tendon, smooth in front for a
bursa ; the shaft is prismoid, curved outward, smaller above
than below, having a sharp internal inferosseons harder for the
interosseous ligament, with the med.idlary foramen directed
upward at the junction of the middle and upper thirds of the
anterior surface. This surface gives attachment to the flexor
longus pollicis and pronator quadratus, and by an oblique line
to the radial head of the flexor sublimis. The external surface
gives attachment to the supinator brevis and pronator teres.
The 'posterior surface (Fig. 62) gives attachment to the supi-
nator brevis, extensor ossis metacarpi pollicis, and extensor
brevis pollicis.

The lower carpal extremity has on its lower face an articular
surface divided by a slight ridge into two facets for the semi-
lunar and scaphoid bones ; upon its inner side the shallow
sigmoid cavity for the ulnar head ; externally the styloid j^rocess
giving attachment by its apex to the external lateral ligament,
by its base to the supinator longus muscle ; and on its posterior
and external convex surfaces are five grooves for the extensor
tendons.

How is this bone developed ?

By three centers : one for the shaft (eighth fetal week) :

THE FOREARM.

101

Ulna

/./ V,\V liiiiis digi-
tornm.

For extensor carpi iilnaris.
'-1-hr rjttnsor minimi digiii.

For ezl. carpi rod. longio, .
Extejisor carpi riidi-tli.i hrevin. .
Exlf.iisor lonyus pollicis.

Fi<;. Ci'l. — Ii<jn<'s of the left foroarin, postorior siirfnre

/ • / KxU-naor ivAicis.

( Extensor communis digitorum.

102

ESSENTIALS OF HUMAN ANATOMY.

one for the carpal extremity (second year) ; and one for the
head (fifth year, joins the shaft at puberty) ; bone coossified
by about the twentieth year.

Give the muscular attachments.

The biceps, the supinator brevis, flexor digitorum sublimis
and longus pollicis, pronator quadratus, the extensor ossis
metacarpi and brevis polUcis, pronator teres, and supinator
longus.

The Hand.

Into what segments is the hand divided ?

Into the carpus (eight bones), metacarpus (five bones), and
phalanges (fourteen bones) ; total, twenty -seven bones.

Describe the arrangement of the carpal bones.

They are placed in two rows of four each ; thus, enumerat-
ing from the radial to the ulnar side, with palm upward ; first,

or proximal row: scaphoid^, semi-
lunar \ cuneiform °, pisiform p; sec-
ond, or distal row : trapezium', tra-
pezoidVj OS magnum', unciform**.

With how many bones does each
articulate ?
Scaphoid, five ; semilunar, five ;
cuneiform, three; pisiform, one;
trapezium, four; trapezoid, four;
OS magnum, seven ; unciform, five.

Describe the chief peculiarities of
each bone (Figs. 68, 64, and

65).

The scaphoid^ (boat-shaped) has
on the anterior surface a tuberosity ;
a transverse groove on the dorsum
parallel to the convex articular sur-
face for the radius ; facets for the os magnum and semilunar
bones on its inner surface ; on its lower surface are facets for
the trapezium and trapezoid.

The semihinar^ (half-moon) presents a convex facet above
for the radius and a part of the triangular fibro-cartilage ; on

Fig. 63.— Right carpal bones,
dorsal surface (Leidy).

THE HAND.

103

«,' «'.t>t»^

Carpui

Metacarpus

Z^Rovf

i r.Rotir

Fig. 01.— Bones of the left huinl, dorsal surfufe (tiray).

its outer face a semilunar facet for the scaphoid ; on its lower,
a concave one for the os magnum and apex of the unciform ;
a (jiiadrilateral one on the inner face for the cuneiform.

Tile ciuu'jform.^ (wedge-shaped) has an oval facet in front for

104 ESSENTIALS OF HUMAN ANATOMY.

the pisiform ; one external for the semilunar ; an inferior con-
cavo-convex facet for the unciform ; a superior convex facet
f(jr the triangular fibro-cartilage.

The pisiform '' is rounded, with one ovoida) facet for the
cuneiform.

The trapezium^ is obliquely grooved on its palmar surface
for the tendon of the flexor carpi radialis ; superiorly is a con-
cave facet for the scaphoid ; below, a saddle-shaped one for the
first metacarpal : internally, one large concave facet for the
trapezoid, and a smaller one for the second metacarpal.

The trapezrjicV^ is wedge-shaped, apex palmar, has four artic-
ular surfaces touching, separated by sharp edges, the external
for the trapezium ; inferior (like a ridge-roof), for the second
metacarpal ; internal, for the os magnum ; superior for the
scaphoid.

The OS magnum ' has superiorly a convex head for the sca-
phoid and semilunar, a neck and body ; below, facets for three
metacarpal bones ; externally, one for the trapezoid ; internally,
one for the unciform.

The unciform'' is triangular, has a sigmoid internal articular
facet for the cuneiform ; two facets below for the fourth and fifth
metacarpals ; one, external, for the os magnum ; by apex with
the semilunar; from the palmar surface projects the curved
unciform process.

When do these bones ossify?

Os magnum and unciform, during the first year ; cuneiform,
third year ; trapezium and semilunar, fifth year ; scaphoid,
sixth year; trapezoid, during the eighth year; pisiform, about
the twelfth year.

(The muscular attachments to the carpal and tarsal bones
will be given under the Muscular System.)

Describe the metacarpal bones.

They are five long bones, with shaft, head, and base. The
first metacarpal (sometimes considered a phalanx) is shorter,
has only one facet on the base, and has one ossific center for
the shaft (eighth fetal week) and one for the haae (third year).
The second metacarpal has four facets on the base for the tra-
pezium, trapezoid, os magnum, and third metacarpal; it, in
common with the rest, has one ossific center for the shaft

THE HAND.

105

Car fins

rLE»OR,CMlFI Ul."

FLCXOR BSEVIS MlNIMi OICIT

FLtHOB 05SIS METACIRP
MINIMI DICITI

Me.facar/ius

FLCX

DREVIS

&

ABOU

CTOB

RAINIMI

OICITl

^

<%V

9

f^

«

$

^ c

X

Fig. 65.— Bones of the left hand, palmar surface (Gray).

(eighth fetal week) and one for the head (third year ; they
coiissify by the twcritictli year). The third incffirdrjHfJ articu-
lates with tlu' o.s iMaixnuiii ; on the ulnar side it has two small

106 ESSENTIALS OF HUMAN ANATOMY.

facets for the fourth metacarpal, and a single facet on the radial
side for the second metacarpal ; the outer angle of its base is
the styloid process. The fourth metacarpal has two facets for
the unciform and the os magnum, a single fjK-et on the ulnar
side for the fifth metacarpal, and two small ones on the radial
side for the third metacarpal. The Ji/th metacarpal articulates
with the unciform by a concavo-convex facet, has only a lateral
facet on the radial side for the fourth metacarpal, and on the
ulnar side a prominent tubercle for the extensor carpi ulnaris
tendon.

Describe the phalanges.

They are fourteen in number — three for each finger, and two
for the thumb — they are long bones, having a shaft, base, and
cond3^1es, except those of the distal row. The bases of the
first row. cup-shaped, articulate with the heads of the meta-
carpals ; those of the second and third have a double concavity,
separated by a median ridge, and articulate with the condyles
of the row above ; the distal extremities of the ungual phal-
anges have rough, horse-shoe shaped tubercles, ungual proce.^ses,
on their palmar surfaces for attachment of the pulp of the fin-
ger ; they ossify by one center for the shaft (eighth fetal week),
and one for the base (third to fifth year) ; uniting in from
eighteen to twenty years.

BONES OF THE LOWER EXTREMITY.

They include those of the hip, f^'f'ff^i, ^^ff, andyoo^

The Thigh.

Describe the femur.

It is the longest bone of the skeleton, and inclines toward its
fellow to bring the knee-joint near the center of gravity dur-
ing walking, this obliquity being greater in the female, from
the breadth of the pelvis, and in a short person than in a tall
one of either sex.

The head (Fig. GO), forming rather more than a hemisphere,
directed upward, inward, and forward, has behind and below its
center the fossa capitis for the ligamentum teres. The neck,
joining the head with the shaft, is flattened and pyramidal ; in
the adult male it forms an obtuse anirle with the shaft of about

THE THIGH.

107

mvtftr tenihm

•1? »»fL-.Tiy»

Fig. 06.— Ki^ht femur, anterior
surface.

Fig. (17.— Kifcht femur, posterior
(Gray.) surface.

108 ESSENTIALS OF HUMAN ANATOMY.

125°. After ossification is completed, twenty years, this angle
does not change nor does the neck become liorizontal.

The great trocJuinter is a large, irregular, quadrilateral emi-
nence, directed upward, outward, and backward, marked on its
external surface by a diagonal line for the gluteus medius ;
below and behind this is a smooth surface for a bursa beneath
the gluteus maximus ; in front is inserted the gluteus minimus ;
superiorly is the pyriformis ; and upon its inner surface is the
digital fossa for the tendon of the obturator externus muscle ;
and above that the internal obturator and gemelli muscles are
inserted.

The lesser troclianter (Fig. 67), small and conical, projects
from the lower back part of the base of the neck, receiving
the insertion of the psoas muscle above and the iliacus below.

The anterior B,nd jxjsterior intertrochanteric lines connect these
processes, the latter being the more prominent, while to the
former is attached the anterior portion of the capsular liga-
ment. At the middle of the posterior intertrochanteric line is
a tubercle for the quadratus femoris muscle, sometimes a Unea
qiiadrati.

The shaft^ broad arid cylindroid at either extremity, narrow
and triangular in the center, slightly curved forward, has its
meduUary foramen at the junction of the middle and lower
thirds of its posterior surface, directed upward ; and from its
anterior surface arise the crureus and subcrureus muscles.

The Unea aspera, a prominent longitudinal ridge occupying
the middle third of the posterior surface, has an external and
an internal lip, and an intermediate space ; above, it divides
into three lines, one directed upward to the base of the greater,
one to the base of the lesser trochanter, a third, the most inter-
nal, continuous with the anterior intertrochanteric line, forming
with it the spiral line, while below the linea aspera bifurcates
to inclose the smooth popliteal space, the inner division grooved
for the femoral vessels. In general terms, this line and its
subdivisions have attached the following muscles : the vastus
internus and externus, the pectineus, the three adductors, the
short head of the biceps, and the gluteus maximus.

Of the two condf/les, the internal is the longer by about half
an inch, to bring both condyles on the same horizontal plane
in the normally oblique position of the femur; above each con-
dyle, behind, is a depression for the gastrocnemius (above the

THE PATELLA. 109

external the plantaris muscle also originates) ; separating them
is the iiitcrconch/loid notch ^ to whose sides are attached the cru-
cial ligaments ; in front, the condyles form a continuous artic-
ular surface, the trochlea ; the outer, as well as the inner, con-
dyle presents an epicondyle upon its free surface for the lateral
ligaments, beneath which, on the outer condyle, is a groove for
the tendon of origin of the popliteus muscle ; above the inter-
nal condyle is a small adductor tahercle for the tendon of the
adductor magnus.

Give the development of the femur.

By five centers : one for the shaft (fifth fetal week) ; one
for the condyles (ninth fetal month) ; one for the head (end
of the first year) ; one for the greater trochanter (fourth year) ;
one for the lesser trochanter (thirteenth to fourteenth year);
all coossified by the twentieth year in the reverse order of their
appearance.

Give the muscular attachments.

The three glutei, pyriformis, two obturators, gemelli,
quadratus, psoas, iliacus, two vasti, short head of biceps, pecti-
neus, three adductors, crureus, subcrureus, gastrocnemius,
plantaris, and popliteus.

The Patella.

Describe the patella (Fig. 68).

It is flat, triangular, placed at the front of the lower end
of the femur, and, being developed in the quadriceps tendon,

11. h

Fio. 68.— Right ijatella : a, anterior surface ; 6, posterior surface.

iitf probably a sesamoid bone ; the convex anterior surface is
roughened ; the posterior mrface is divided by a vertical ridge
into two smooth facets for the trochlea, the outer being the

110 ESSENTIALS OF HUMAN ANATOMY.

broader and deeper ; the apex ^ives attachment to the liga-
mentum patellae ; and the superior and lateral borders to the
rectus fenioris. crurcus, and vasti muscles. It is developed by
one center (about the third year) ; the muscular attachments
have been already given.

The Leg.

Describe the tibia.

The shin-bone, situated at the inner front part of the leg, is
only second in length to the femur ; the head^ or upper ex-
tremity, is large and expanded on each side into two lateral
tuberosities^ bearing upon their upper surfaces smooth concave
ovoidnl facets for the femoral condyles, between which is the
vertical, bifid spine for the extremities of the semilunar fibro-
cartilages, the depressions in front and behind its base giving
origin to the crucial ligaments. Below, in the mid-line, in
front of the head, is the tubercle for the ligamentum patellae
(Fig. 60) ; separating the tuberosities behind is the popliteal
notch, giving attachment to the posterior crucial ligament ; on
the posterior surface of the inner tuberosity is a transverse
groove for the insertion of the semimembranosus tendon ; upon
the back of the outer tuberosity, facing downward, is a facet
for the head of the fibula ; running obliquely from this facet,
downward and inward, on the posterior surface (Fig. 70), is the
oblique line for the popliteal fascia and muscle, part of the soleus,
flexor longus digitorum, and tibialis posticus muscles ; just
below the line, directed downward, is the medullary canal, the
largest in the skeleton. The external surface (Fig. 69) gives
attachment to the tibialis anticus. The internal surface is
largely^ subcutaneous ; it gives attachment above to the sarto-
rius, gracilis, and semitendinosus.

The prismoid shaft has three borders, the anterior, called the
crest or sliin. and the external or interosseous ridge, for the inter-
osseous membrane, and the internal for the soleus and flexor
longus digitorum. The loioer extremity, smaller than the upper,
has an inferior concave surface for the astragalus, an external
rough triangular surface for articulation with the fibula ; it is
grooved posteriorly for the flexor longus hallucis tendon ; has
projecting downward internally the internal malleolus, which
articulates by its outer surface with the side of the astragalus,
is grooved behind for the tibialis posticus and flexor longus

THE LEG.

Ill

Bead

-/^^x

i-'f' Jij,' .

\ V^- !■

* TIBIA

■UiUUtU^

'tt/lmd frttess

Fig. 69.— Bones of the right leg, ante- Fig. 70.— Bones of the right leg, poste-
rior .surface. (Gray.) rior surface.

digitorum tendons, and has attached to its tip the internal
lateral ligament.

112 ESSENTIALS OF HUMAN ANATOMY.

How is this bone developed?

By three centers : one for the shaft (seventh fetal week) ;
one for the head (before or at birth) ; one for the lower end
(second year) ; bone coossified by the twenty-first or twenty-
second year.

Give the muscular attachments.

Semimembranosus, tibialis anticus and posticus, biceps, ex-
tensor and flexor longus digitorum. sartorius, gracilis, semi-
tendinosus, popliteus, soleus, and quadriceps femoris by the
ligamentum patellae.

Describe the fibula (peroneal bone).

It is long, slender, and is placed externally nearly parallel to
the tibia.

The head or upper end articulates by a flattened facet with
the external tibial tuberosit3\ and is prolonged upward behind
into the styloid process for the short external lateral ligament ;
below and behind is attached the long external lateral liga-
ment and the biceps tendon.

The shafts triangular and twisted (Figs. 69 and 70), has
four borders and four surfaces ; the borders are antero-external,
antero-interncd (interosseous), poster o-external^ and postero-
internal; the surfaces are anterior^ external^ posterior, and
internal. To the anterior surface are attached the extensor
longus hallucis. extensor longus digitorum and peroneus tertius
muscles ; to the external surface, the peroneus brevis and
longus ; to the posterior surface, the soleus and flexor longus
hallucis ; to the internal surface, the tibialis posticus. The
external malleolus forming the lower extremity, longer than the
internal, articulates by its inner surface with the outer side of
the astragalus ; is grooved behind for the peroneus longus and
brevis tendons ; to its summit is attached the middle, and to
rough depressions in front and behind, the anterior and poste-
rior fasciculi of the external lateral ligament of the ankle.

Describe its development.

By three centers: one for the shaft (eighth fetal week);
one for the malleolus (second year) ; one for the head (fourth
year) ; bone coossified by the twenty-fifth year, but, contrary to
ride, the lower epiphysis unites frst.

THE FOOT.

113

Give the muscular attachments.

Biceps, soleus, three peroneals, the extensor and flexor of the
great toe, the extensor longus digitorum, and tibialis posticus.

The Foot.

Into what segments are the bones of the foot divided?

Into the tarsus (7) ; inetafdrsiis (5j ; and pkalanyes (IJ:; ;
total, 26 bones (Figs. 71, 72 and 73).

Name the tarsal bones.

Oalcaneum'^ (os calcis), astragalus ^ cuboid^, navicular^, in-
ternal, middle **, and external' cuneiform.

Give the chief peculiarities of each tarsal bone.

The astragalus^ has a large rounded licad'^ a neck^ a hody^^
superiorly a trochlear surface broader in front than behind, for
the tibia, and continuous with it on either
^\([q facets for the internal and external mal-
leolus ; the under surface presents two
articular facets, separated by a groove for
the calcaneo-astragaloid ligament, running
obliquely forward and outward ; that behind
for the calcis, that in front partly for the cal-
cis, but chiefly for the calcaneo-navicular liga-
ment ; it articulates with the tibia, fibula, os
calcis. and navicular, and is developed by one
center (seventh fetal month).

The OS calcis'^, tbe largest tarsal bone,
forms by its tuherositif^ the heel, has a
groove on its upper surface to correspond to
that of the astragalus ; behind and in front
of which are two articular facets for the
same bone : on the inner side projects the
sustentaculum tali supporting the internal
articular surface ; beneath this process the
innt^r surface of the bone is deeply concave
for the flexor tendons, plantar vessels, and
nerves ; its anterior c(nicavo-convex surface
articulates with the cul>oid ; on the under
surface arc an inner and an outer tuhercle ;
it articulates with the astragalus and cuboid, and is dc^'clopcd

Fk;. 71.— Bones of
tlu' rif^lit foot, dorsal
surface (Leidy).

114 ESSENTIALS OF HUMAN ANATOMY.

from two cc'iiter.s, one for the main mass (sixth fetal months
and one for tlie tuberosity (tenth year); union alter puberty.

The cuhoiil lias one articular surface each ior the os calcis,
external cuneiiorm. the fourth and fifth metatarsals, and some-
times lor the navicular; upon the under surface is a deep
groocc for the peroneus longus tendon, and behind this a ridge
terminating externally in a tubcrosit)/ ; it is developed from one
center (ninth fetal monthj.

The navlciihtr^ situated internally, is concave behind for the
head of the astragalus ; is convex in front with {\\yq,q facet s for
the three cuneiform bones ; externally there may be di. facet for
the cuboid ; and internally, below, is the tuberosity for part of
the posterior tibial tendon ; it is developed from one center
(fourth year).

The internal cuneiform^ the largest, is placed at the inner side
of the foot, has its base downward, upon which is the tuberosity
for partial insertions of the tibialis posticus and anticus ten-
dons ; in front is a kidney-shaped y«ct'? for the first metatarsal ;
externally are two /r/tr^.s for the second metatarsal in front, the
middle cuneiform behind ; posteriorly 2^ facet for the navicular ;
it is developed by one center (third year).

. The middle cuneiform, the smallest, has its base upward, a
triangular facet in front for the second metatarsal, another be-
hind for the navicular, along the posterior and superior borders
of the inner face 2l facet for the internal cuneiform ; and exter-
nally a smooth facet for the external cuneiform ; it is developed
by one center (fourth year).

The external cuneiform is intermediate in size with its base
upward, has an anterior triangular facet for the third meta-
tarsal ; another posterior for the navicular ; two upon the in-
ternal surface for the second metatarsal and middle cuneiform ;
and two upon the outer surface for the fourth metatarsal and
for the cuboid : it is developed by one center (first year).

Describe the metatarsal bones.

These five long bones have prismoid shafts^, anteriorly a
head for articulation with the phalanges, posteriorly a base
articulating with the tarsus and wnth one another.

The ///-.s^ metatarsal \ii, .shorter, much stouter than the others,
and articulates with the internal cuneiform : developed by one

THE FOOT.

115

Civot" /-» tnJtn cf
iLUui L«ilCS> HALLUCIS

Tarsus

Iniurmca UaJm ^

2f^t»T «Rt»H OrtlTORUMI

I'Aalanjes

l«T igNSuS HALLUCIS

Fin. 72.-Bones of the ri>,'ht foot, dorsal surfiicc (<iray).

IKJ ESSENTIALS OF HUMAN ANATOMY.

ABDUCTOR

lUienh of
A'avicutar

Two aeaa-
moid bones

TER HEAD OF ACCESSORY

FLEXOR BREVIS HALLUCIS

rLcioA finrvis

t JlBOUCTOe
mHiMl OICITI

FLEXOR LONGU:
DIGITORUM

Fig. 73— Bones of the right foot, plantar surface (Gray).

THE ARTICULATIONS. 117

center for the shaft (seventh fetal weekj ; one for the hase
(third year), united by the twentieth year.

The second metatarsal^ the longest, articulates posteriorly
with the middle cuneiform, internally with the internal cunei-
form, externally with the external cuneiform and third meta-
tarsal, four bones in all : developed by one center (seventh fetal
week) for the shifty one for the head (third year), united at
twenty years.

The third metatars<d has ^ facet on the base for the external
cuneiform, two on its inner side and one on its outer for the
contiguous metatarsal : developed like the second.

The fourth me.tatarscd articulates behind with the cuboid,
has a facet on the inner side divided into an anterior portion
for the third metatarsal, a posterior for the external cuneiform,
and externally one facet for the fifth metatarsal, under which
is a deep groove : developed like the second.

The ffth metatarsid has a triangular oblique surface for the
cuboid, continuous internally with one for the fourth meta-
tarsal ; externally a tubercular eminence : developed like the
second.

Describe the phalanges.

They resemble closely those of the hand, except that they
are strongly compressed from side to side, instead of from be-
fore backward : ossification also similar, but later. Thus, the
shaft centers appear from the second to the fourth month, and the
epiphyses appear at the bases in the fourth to the eighth year.

THE ARTICULATIONS.

How are the articulations classed?

In three divisions : 1. Synarthrosis^ immovable, as most of the
cranial articulations; 2. I/emiarthrosis, yielding (limited mo-
tion), as that between the vertebral bodies, or at the pubic
symphysis ; 8. Diarfhrosis, freely movable.

Into what classes are the synarthroses divided?

1. S//iiehondrosis, union by cartilage, as sacro-iliac joint;
2. Sf/ndesmosis, union by ligament, as sutures ; 3. ^Synostosis,
union by bone, as spheno-occipital. Sutures are true and false.

1. iSnfifra vera, including three sub-classes — S. dentata,

118 ESSENTIALS OF HUMAN ANATOMY.

tooth-like, as the interparietal suture ; S. sfrrafa, like saw
teeth, as the interfrontal ; JS. Umbosa^ when bevelled in addi-
tion to dentation, as the fronto-parietal. The S. notlia (false
suture) includes *S'. squamosa^ formed by two overlapping bev-
elled edges, as the squamo-parietal suture ; and the ^S'. har-
monia, mere apposition of roughened surfaces, as the two su-
perior maxillary bones.

2. SchinJj/lesis, where a thin edge is received into a cleft or
groove, as the vomer between the superior maxillary and pal-
ate bones.

3. Gompliosis^ the insertion of a conical process into a socket,
as teeth in their alveoli (not really a bony articulation, as teeth
are not bones).

How are diarthroses classed?

As arthrodia^ gliding joints in tarsus and carpus ; enarthroses,
ball-and-socket joint — hip- or shoulder-joints ; ginglymns, hinge-
joint — elbow-joint; frochoides, or lateral ginglymus^ a pivot
turning within a ring, as the superior and inferior radio-ulnar
and central atlanto-axial ; condyloid where surfaces are ellipti-
cal, as radio-carpal (wrist) ; reciprocal reception, or saddle-
shaped surfaces, as first carpo-metacarpal (base of thumb).

Motions. — Flexion, extension, adduction, abduction, circum-
duction (a combination in succession of the four), rotation, and
gliding.

What structures are essential to the formation of each of the
three classes of articulations?

For synarthroses, two or more bones, an interposed layer of
fibrous tissue (sutural ligament) or, perhaps, cartilage (base of
the skull) ; syinjyhyses, an interposed bond of fibro-cartilage,
with strong bands of white fibrous tissue, i. e. ligaments (liga-
ments are sometimes composed of yellow elastic tissue, as the
ligamenta subflava or ligamentum nuchae) ; diarthroses, two or
more cartilaginous-coated surfaces (reducing friction), some-
times interarticular fibro-cartilages to deepen joint-surfaces, as
those of the knee and temporo-maxillary joints, a complete fi-
brous capsule, and often additional ligamentous bands, some in-
terarticular, i.e. within the joint-cavity, and a synovial (serous)
membrane lining the interior of the capsule, but not extending
upon the cartilages ; a similar membrane also forms sacs

THE ARTICULATIONS OF THE TRUNK. 119

(bursae) outside the joints, with which they often communi-
cate, serving to reduce friction of the tendons, ligaments, etc.;
the layer of bone beneath the articular cartilage is the denser
articular lamella; it contains neither Haversian canals nor
canaliculi, but has larger lacunae.

What is the rule as regards the nerve-supply of joints ?

The interior of the joint, the muscles moving it, and the
skin over their insertions, are supplied by the same trunk or
trunks of nerves (this explains the reflex contractions of dis-
eased joints.

The Articulations of the Trunk.

Describe the vertebral articulations.

Formed by the contiguous surfaces of the bodies, Limin.ie,
articular, spinous, and transverse processes ; their ligaments
are :

An iRtervcrtehral connecting fihro-cartilage^ or rZ/'sA:, between
the bodies of all true vertebrae, except the atlas and axis.

An anterior common, ligament^ passing medianly over the
fronts of the vertebral bodies, most firmly attached to their
margins.

A posterior common ligament^ similarly disposed behind the
bodies.

Short or lateral vertehral ligaments, fibers running at most
over three vertebrae, firmly uniting the bodies where the ante-
rior and the posterior common ligaments are deficient.

Ligamenta suhjlava, of yellow elastic tissue, connecting the
laminae from an internal surface above to an upper edge below.

Capsular^, enclosing the articular processes, and lined with
.synovial membrane.

Supra- and inferspinovs, the former connecting the tips, the
latter being interposed between the spinous processes.

Intertransverse, connecting transverse processes; nerves, spinal
in each region; arifer/V?.?, vertebral, pharyngeal, and ascending
cervical arteries in the neck, intercostal arteries in the thoracic
region, and lumbar arteries in the loin.

Describe the occipito-atlantal articulation.

A pair of ginglijnio-arthrodial Joints formed by the con-

120

ESSENTIALS OF HUMAN ANATOMY.

dyles of the occipital bone and the superior articular proc-
esses of the atlas. Its ligaments are :

Two anterior occipito-atlantaP (Fig. 74), extending from the
anterior margin of the foramen magnum to the anterior arch
of the atlas, blending on either side with the capsular liga-
ments ; the second ligament is a rounded cord in the middle
line.

A posterior occipifo-atlantal, much broader, from the poste-
rior margin of the foramen magnum between the condyles, to
the postero-superior border of the posterior arch of the atlas,
and is incomplete on each side for the ingress of the vertebral
artery and egress of the suboccipital nerve.

Two capsular ligaments'' ^ lined with synovial membrane, sur-
rounding the articular surfaces.

Two lateral (or anterior ohli<pie^, passing upward and inward
from the transverse process beyond the vertebral foramen to
the jugular process of the occijjital bone; nerve, suboccipital ;
arteries, from the vertebral.

Describe the atlanto-axial articulation.

The lateral joints are arthrodia, that between the atlas and
odontoid process is trochoides. The ligaments of the lateral

joints and arches are :

Two anterior atlanto-axial*,
membranous, passing between
the lower front border of the
atlas to the front of the axis
with a central rounded cord.

The ])osferior atlaiito-axiid,

stretching between the postero-

inferior edge of the ring of the

. atlas to the superior edge of

the arch of the axis behind ; it

is pierced on each side by the

second cervical nerve.

The anterior^'^ common liii'ament is continued over the

median portions of the above to the occiput, as rounded cords.

Two capsidar^^, synovial-lined, surrounding the articular

processes.

The ligaments of the central atlanto-axial joint are:

The transverse'^ (Fig- 75), extending between the tubercles

Fro. 74.— Occipito atlantal and at
lanto-axial ligaments, anterior view

THE ARTICULATIONS OF THE TRUNK.

121

on the inner surface of each lateral mass of the atlas ; it holds
the odontoid process in* place, and between the two is a synovial
membrane surrounded by a capsule^ the transverso-odonfoid
Joint ; between the odontoid process and the posterior surface
of the anterior arch of the atlas is the atlanto-odontoid articu-
lation, surrounded by a aipside lined with synovial menibrane;
passing upward and downward from the transverse ligament
are two bands, attached above to the basilar margin of the
foramen magnum ; below, to the upper half of the body of the
axis, forming a cross : hence the transverse ligament may be
called the crucial ligamerd ; nerves^ all these joints are supplied
by the second cervical or the loop between it and the suboccip-
ital ; arteries, are branches of the vertebral.

What ligaments connect the axis and occiput?

The posterior common ligament^ extends upward, to be
attached far up the basilar process ; this ligament is usually
regarded as

The occipito-axial or occipito-ccrvical ligament, attached
above to the basilar groove of the occiput, below, to the third

Fig. 73.— Occipito-uxial and atlaiito-axiul Fig. 76.— Temporo-maxillary artic-
ligaments, posterior view. illation, external view.

cervical body and that of the axis (next comes the vertical
part of the crucial already described) ; deepest of all are the
three odontoid ligaments — two lateral occipi to-odontoid, or
check^, extending from the sides of the apex of the odontoid
to the inner edge; of the occipital condyles, while stretching
between the odontoid tip and the under surface of the basilar

122 ESSENTIALS OF HUMAN ANATOMY.

process, close to the foramen magnum, is the central ocdpito-
odontoid^ or ligamentum svspensoriuni.

Describe the tempore -maxillary articulation.

The upper compartment is (n'throdi(d^ formed by the glenoid
fossa and eminentia articularis of the temporal bone and the
upper surface of the fibro-cartilage ; the lower is guighjmoid^
between the under surface of the fibro-cartilage and the condyle
of the lower jaw. The ligaments are capsular^ passing between
the maxillary and temporal bones near their margins, consisting
of ligamentous fibers, which are thicker at certain parts and are
described as :

The external lateral ligament''^ attached above to nearly the
whole length of the lower edge of the zygoma and its tubercle,
below to the outer side of the neck of the condyle of the jaw.

The short internal lateral ligament^ extending between the
spine of the sphenoid and inner edge of the glenoid fossa, and
a ridge on the innqr side of the neck of the condyle.

The long interned latercd ligament (spheno-mandibular liga-
ment), stretching between the spine of the sphenoid and the
forepart of the tip of the inferior dental foramen, the lingula.

The inter eirticular fibro-cartilage^ concavo-convex on the upper
surface, concave transversely below, dividing the joint into two
separate synovial cavities.

The stylo-maxillary ligament^, extending from the styloid
process to the angle of the jaw, is really a process of the deep
fascia ; nerves^ the masseteric and auriculo-temporal branches of
the inferior maxillary nerve; etrteries, temporal, middle
meningeal, ascending pharyngeal, posterior auricular, tympanic
branch of the internal maxillary, and ascending palatine.

Describe the costo-vertebral articulations.

These are each formed (1) between the head of a rib and the
bodies of two adjoining vertebra? (except the first, tenth,
eleventh, and twelfth, which articulate with but one vertebra
e?iQ\i)^hQ\n^ginglymo-art]irrjdifd ; and (2) between the tuberosity
of each rib (except the eleventh and twelfth) and the trans-
verse process of a vertebra, and is artJirodial.

Describe the costo-central articulations.

The ligaments are :

A capsidar ligament*, attached all around each articular

THE ARTICULATIONS OF THE TRUNK.

123

Fig. 77. -Costo-vertebral lig-
aments, autcrior view.

surface, the synovial lining being sub-
divided into two cavities by the

Inter<irticul(ir liganient*, passing be-
tween the ridge on the head of the
rib to the intervertebral fibro-carti-
lage.

The stellate ligament^, or anterior
costo-central, arising from the ante-
rior surface of the head of the rib,
whence the fibers radiate to the ver-
tebra next above, and below to the
adjoining vertebra, and to the inter-
vertebral disk ; nerves^ anterior branches of the spinal nerves ;
arteries, the intercostals.

Describe the costo-transverse articulations.

Arthrodial, ten in number, their ligaments are :

Capsular, attached beyond the margins of the articular facets.

Superior costo-transverse'^ has two sets of fibers: the anterior
passing between the upper border of the neck of the rib to the
transverse process of the vertebra above ; the posterior to the
articular and transverse processes.

Middle costo-transverse, connecting the back of the neck of
the rib with the contiguous transverse process ; it has three
parts, upper and lower and a conjugal ligament passing through
the spinal canal.

Posterior costo-transverse^ stretching from the tip of the trans-
verse process to a rough projection beyond the facet on the
tuberosity of the rib ; nerves^ posterior branches of the thoracic
nerves ; arteries, intercostals and posterior spinal.

Describe the (1) chondro-sternal articulations, i2i the con-
nection between the ribs and costal cartilages,
and (3) the interchondral joints.

(1) The first, sixth, and seventh are synarthrodial, the other
joints are arthrodial. The first, sixth, and seventh have no
synovial membrane; the third, fourth, and fifth have one; the
second has two. The ligaments are capsidar ; the anterior and
posterior thicker segments are described as

Anterior and posterior chondro-sternal ligaments. Occasion-
ally there is an inter articular ligament, notably in the second
chondroid joint, dividing the synovial cavity into two.

124

ESSENTIALS OF HUMAN ANATOMY.

(2) The coiifal cartilages are firmly attached to the cup-like
depression at the end of each rib. and by the periosteum con-
tinued over to form the perichondrium.

(3) The intercliondral articulations^ arthrodlal^ are found
between the edges of the cartilages of the sixth, seventh, and
eighth ribs, sometimes the fifth and ninth, having each a cajiside
lined with synovial membrane. In addition there is an anterior
and a posterior cltondro-xiplioid ligament which binds the
xiphoid cartilage and the sixth and seventh cartilages together ;
nerves^ intercostals ; arteries^ internal mammary or its branches.

Describe the ligaments of the sternum.

The njanubrium and gladiolus are bound together by the
anterior and posterior intersternal ligaments, with a layer of
cartilage between them (an ampliiarthrodial joint ^ sometimes
a diarthrrjdial) ; that between the ensiform cartilage and the
gladiolus is synarthrodial.

Describe the sacro-vertebral articulation.

Similar to other vertebral articulations, but has, in addition,
The sacrodumhar ligament, extending from the transverse

process, pedicle, and body of the fifth lumbar vertebra to the

non-articular portion of the base of
the sacrum and periosteum of the ilium,
and anterior sacro-iliac ligament.

The iliodnmhar ligament^ (Fig. 78),
extending from the front surface and
tip of the transverse process of the
fifth, and lower edge and front sur-
face of the transverse process and
pedicle of the fourth lumbar verte-
bra, to the inner lip of the iliac crest;
nerves, fourth and fifth lumbar, sympa-
thetic ; arteries, ilio-lumbar, last lum-
bar, and lateral sacral.

Describe the sacro-iliac articulations.

They are synarthrodial, formed be-
tween the auricular surfaces of the
ilium and sacrum, and have the fol-
lowing ligaments upon each side, in addition to the symphy-
seal cartilage :

Fig. T8.— Ligaments of pelvis
and hip, posterior view.

THE ARTICULATIONS OF THE TRUNK. 125

The anterior sacro-iliac^ (Fig- 81), from the three first pieces
of the sacrum to the ilium on their pelvic surfaces.

The poster lor sacro-lUac'^ (Fig. 78), very strong, extending
between the back of the sacrum and the posterior two inches
of the iliac crest, including the posterior superior iliac spine.

An otjUtpie Ugrimeiit^ stretching between the third articular
tubercle of the sacrum to the po.sterior superior iliac spine.

Superior and inferior bands of fibrous tissue closing in the
joint above and below, belong to the anterior sacro-iliac.

The interosseous ligament^ strongest of all, consists of numer-
ous ligamentous bands passing between the contiguous rough
surfaces of the sacrum and ilium ; nerves^ from the superior
gluteal, posterior sacral, and lumbo-sacral cords; arteries, t\iQ
gluteal, ilio-lumbar, and lateral sacral.

Describe the ligaments connecting the sacrum and ischiatic
bones on each side.

They are the :

Greater sacro-sciatic^, thin, triangular, passing from the pos-
terior inferior iliac spine, fourth and fifth articular sacral tu-
bercles and lower lateral margin of the sacrum , and from the
coccyx to the inner margin of the ischiatic tuberosity, forming
here the falciform process.

The lesser sacra-sciatic*, anterior to the former, of same shape,
stretching between the lateral margins of the sacrum and
coccyx and the spine of the ischium. It is blended with
the coccygeus muscle.

These ligaments convert the two sacro-sciatic notches into
the greater (by lesser ligament) and the lesser (by greater
ligament) sacro-sciatic foramina, described under the iliac and
ischiatic bones.

Describe the sacro-coccygeal articulation.

AnrjtliiartlirodiaL its ligaments are :

An inter articular fihro-cartilage, like that between vcrtebn\}.

An anterior sacro-coccygeal, a continuation of the anterior
common vertebral.

A posterior sacro-coccygeal, a continuation of the posterior
common, of the supraspinous and intcrspinous ligaments and
the filum terminal''.

IritprconiiKil ;ind intertransverse bands, connecting jiarts of

120 ESSENTIALS OF HUMAN ANATOMY.

the same name ; nerves, anterior and posterior branches of the
fifth sacral and coccygeal, posterior division of the fourth, and
probably the second and third sacral ; arteries, lateral and
median sacral.

Describe the pubic articulation.

Ampliuirthrudial, between the two pubic bones ; its liga-
ments are :

An interosseous Jib ro-cartilage, or interpuhic disk.

A suprapubic, extending along the crest of the pubes on
each side, blendino; with the fibro-cartilao-e.

K posterior, little more than periosteum.

An anterior, thick, strong, decussating, attached to the con-
tiguous portions of the body and rami.

An inferior, or subpubic, arched, filling up the angle between
the pubic rami ; nerves and arteries of no special moment.

The obturator iij((nie/it^ is a fibrous membrane filling the
same named foramen, except at the upper and outer part.

The Articulations of the Upper Extremity.

Describe the stemo-clavicular articulation.

An arthrodial joint formed between the sternal end of the
clavicle and the sternum and cartilage of the first rib, having
an interarticular fibro-cartilage usually dividing the joint into
two distinct synovial sacs ; its ligaments are :

A capsular, passing between the articular margins and firmly
connected with the fibro-cartilage. Its strengthening bands are
the anterior and posterior stemo-clavicular ligaments.

The inter clavicidar, passing from the posterior superior angle
of the inner extremity of each clavicle, and attached to the
sternum between.

The rhomboid, or chondro-clavicular, stretching from the
upper border of the first costal cartilage to the rhomboid
impression of the clavicle ; nerves, from the descendens cervicalis
and from the nerve to the subclavius ; arteries, contiguous
muscular branches.

Describe the acromio-clavicular articulation.

An arthrodial joint formed by the outer extremity of the
clavicle and the acromion process of the scapula ; it rarely has
complete interarticular fibro-cartilage and two synovial sacs,

ARTICULATIONS OF THE UPPER EXTREMITY. 127

otherwise there is only one sac ; its ligaments are, the capsular^
attached to the anterior and posterior borders, upper and lower
surfaces of the acromion and clavicle ; the superior and inferior
acromio-clavicular ligamentii.

The cor((co-clavicul<ir'\ composed of the couoicP, conical, at-
tached by its apex to the base of the coracoid process, by its
base to the conoid tubercle of the clavicle and a line internal
to it (Fig. 79).

The trapezoid, broad and thin, quadrilateral, stretching be-
tween a ridge on the upper surface of the coracoid to an ob-
lique line on the under surface of the clavicle ; iwrves, supra-
scapular and circumflex ; arteries, suprascapular, anterior cir-
cumflex, acromio-thoracic.

What are the proper ligaments of the scapula?

The coraco-acromiai\ a triangular flat band, attached by its
apex to the summit of the acromion, by its base all along the
outer border of the coracoid process. Its anterior and poste-
rior edges are thick and its center thin. The superior transverse
ligament bridges the suprascapular notch. It has two bands.
The inferior transverse, or spina-glenoid, is near the base of the
spine in the infraspinous fossa. The glenoid belongs properly
to the scapula, but is described with the shoulder-joint.

Describe the shoulder-joint (Fig. 79).

An enartlirodiid joint formed by the head of the humerus
and glenoid fossa of the scapula. Its synovial membrane is
reflected upon the tendons of the biceps and subscapularis, and
the joint has numerous bursae in its vicinity, with some of
which it communicates, notably the subcoracoid and subscapu-
lar ; the ligaments are, capsular^, from the margin of the gle-
noid fossa above, to the anatomical neck of the humerus below.
Strengthening bands are outside and inside the capsule ; the
former are coraco-]nrnier<d^. transverse hmneral ligaments, and
surrounding tendons. Within the joint-cavity are three gleno-
hnmeral ligaments ; the ni>i>er one, or Flood's, is just below and
parallel to the biceps tendon ; the middle one, or internal of
Sehlenmi, is oblirjue ; the inferior gleno-himeral is the inferior
or hroad ligament of Scldemm.

The glf'iioid is a dense fibro-cartilage, triangular in cross-sec-
tion, attached to the circumference of the fossa, deepening the

128

ESSENTIALS OF HUMAN ANATOMY.

socket, and continuous above with the long head of the biceps
muscle', which really serves as one of the cldef ii(/amenfs ;
nerves, suprascapular, circumflex, subscapulars ; arteries, supra-
scapular, subscapular, dorsalis scapulae, anterior and posterior
circumflex.

Describe the elbow-joint iFig. 80).

Ginglymoid, formed by the lower end of the humerus,
greater and lesser sigmoid cavities of the ulna and head of the
radius ; its ligaments are :

Fig.

79 —Left shoulder-joint and scap-
ular ligaments

Fig. 80.— Left elbow-joint,
antero-internal aspect.

A capsule^, large, capacious, and usually described as show-
ing (interior, posterior, intenuiK and external ligaments.

The anterior ligament ^ extends from the humerus, above the
articular surface and coronoid fossa, to the front of the coronoid
process of the ulna and orbicular ligament.

The posterior ligament extends from the back of the humerus,
from condyle to condyle, and through the olecranon fossa, to
be attached all around the olecranon process, close to its articu-

ARTICULATIONS OF THP: UPPER EXTREMITY. 129

lar margin, a few fibers to the back of the neck of the radius
and to the orbicular ligament.

The external hiteral radiates from the lower part of the con-
dyle to end in the orbicular ligament, sending a few fibers to
the neck of the radius and interosseous border of the ulna.

The internal lateral'^ triangular, rises from the anteroinferior
aspect of the inner epicondyle, and is attached to the inner side
of the coronoid and olecranon processes. There are three
sets of fibers : humero-coronoid, humero-olecranon^ and ( a trans-
verse set) olecrano-coronoiil ; nerves, musculo-cutaneous, ulnar,
median, musculo-spiral ; arteries, the two profunda arteries,
anastomotica magna, anterior and posterior ulnar recurrent,
posterior interosseous recurrent, radial recurrent, and some
muscular branches.

Describe the superior radio-ulnar articulation.

It is a diarthrosis rotatoria, or tvoclioideii, formed by the
head of the radius and lesser sigmoid cavity of the ulna, its
synovial membrane being continuous with that of the elbow-
joint ; its only ligament is the

Orhicular^, surrounding the head of the radius, forming only
four-fifths of a circle by most of its fibers, but some, continued
below the sigmoid cavity, form a complete circle ; nerves and
arteries as above. This ligament and articulation belong to the
elbow-joint.

Describe the inferior radio-ulnar articulation.

A lateral ginglyraus, formed by the ulnar head and sigmoid
cavity of the radius ; its synovial membrane is so loose as to be
called the niendjrana sacciformis ; the ligaments are :

The triangular Jibro-cartilage attached by its apex to the
fossa at the base and to the apex of the styloid process of the
ulna, by its base to the margin of the radius below the sigmoid
cavity.

The anterior radio-ulnar stretches between the anterior edge
of the sigmoid cavity of the radius to the rough surface above
the articular surface of the ulna.

The posterior radio-idnar is similarly attached behind ; nerves,
anterior interosseous of the median and posterior interosseous
of the musculo-spiral ; arteries, anterior and posterior inter-
osseous and carpal arches.
9

130 ESSENTIALS OF PIUMAN ANATOMY.

What other ligaments bind the radius and ulna together?

The interoaseous membrane^, passing obliquely downward
and inward from the interosseous ridge of the radius to
that of the ulna.

The ohllqw'\ attached to the tubercle at the base of the
coronoid process of the ulna above, and below to the shaft of
the radius a little below its tuberosity ; nerves and arteries are
from the anterior interosseous nerve and artery.

Describe the wrist-joint.

It is a amdijloid articulation with elliptical surfaces. Its
motions are flexion and extension, adduction and abduction, a
combination of these producing circumduction. It has no rota-
tion ; this is accomplished by supination and pronation of the
bones of the forearm. It is formed between the radius and
triangular fibro-cartilage above, and the scaphoid, semilunar,
and cuneiform below ; its ligaments are, cajysnlar^ with four
strengthening bands, an anterior radio-carpal^ passing between
the radius, the styloid process of the ulna, and the fibro-carti-
lage to the first and second rows of the carpal bones.

A posterior radio-carpal is similarly disposed, passing from
the radius to the first three carpals.

An internal lateral, fan-shaped, passing from the styloid
process of the ulna to the pisiform, and the side and back of
the cuneiform bone.

An external lateral, radiating from the tip and front of the
styloid process of the radius to the scaphoid, os magnum, and
trapezium ; the posterior annidar ligament also assists the wrist-
ligaments proper; nerves, ulnar, median, and posterior inter-
osseous ; arteries, anterior and posterior carpal arches, anterior
and posterior interosseous.

Describe the carpal articulations.

Arthrodial, they consist of (1) the joints between the bones
of the first row ; (2) those between the bones of the second ;
and (3) those between the two rows, the medio-carpal.

(1) The pisiform has a separate capsular ligament, with two
bands connecting it with the unciform and base of the fifth
metacarpal, and a separate synovial membrane ; the other three
bones of this row are connected by

ARTICULATIONS OF THE UPPER EXTREMITY. 131

Two interosseous ligaments^ between the scaphoid and lunar,
and the lunar and cuneiform ; and

Two dorsal and tioo palmar ligaments, binding together the
same bones.

(2) The four bones of the second row have

Two or three interosseous ligaments^ connecting the os mag-
num with the trapezoid externally (inconstant), the unciform
internally ; a third between the trapezium and trapezoid ; and

Three dorsal and tltree palmar ligaments, passing between
the contiguous bony surfaces.

(3) The two rows are united by the dorsal and palmar liga-
ments and two lateral, continuous with those of the wrist-
joint ; the anterior annular ligament, passing from the hook of
the unciform and from the pisiform to the trapezium and
scaphoid bones, is an important carpal ligament. The synovi<d
membrane is common to all the carpal joints, except the
pisiform ; nerves, posterior interosseous, median and ulnar ;
arteries, anterior and posterior carpals of the radial and ulnar,
carpal of the anterior interosseous, carpal of the deep palmar
arch, and terminal twigs of the anterior and posterior inter-
osseous.

Describe the carpo-metacarpal articulations.

That of the thumb is one of reciprocal reception, and enjoys
all movements but rotation of the metacarpal on its own axis ;
it possesses a distinct synovial sac, and its only ligament is the

Capsule attached around the articular surfaces of the trape-
zium and first metacarpal.

The other four metacarpals from arthrodial joints with the
adjacent carpal bones, with three dorscd ligaments passing
from the trapezium, trapezoid, and os magnum to the second
bone ; tvxj ligaments from the os magnum to third ; two liga-
ments— one from the magnum, the other from the unciform
— to fourth ; one ligament connecting with the fifth metacarpal
and unciform.

One palmar ligament passes from the trapezium to the
second metacarpal ; 'one ligament each from the trapezium,
magnum, and unciform to the third ; one ligament connects the
unciform and fourth bone ; one ligament passes from the
unciform to the fifth metacarpal.

An interosseous ligament connects the contiguous inferior

132 ESSENTIALS OF HUMAN ANATOMY.

angles of the os magnum and uiiciforni with the adjacent sur-
faces of the third and fourth metacarpal bones ; the mjuovial
membrane is that common to intercarpal joints, sometimes the
joint formed between the fourth and fifth metacarpals and
unciform forms a separate synovial sac ; nerves and arteries are
the same as those for the medio-carpal joint.

Describe the union of the metacarpal bones with one
another.

That of the thumb is isolated ; the bases of the others are in
contact, forming artlirodtal joints, lined by prolongations of
the synovial sac of the carpus, and are bound together by j)al-
mar^ dorsal^ and interosseous ligaments ; the deep transverse
ligament binds together their heads ; it is a part of the
palmar fascia.

Describe the metacarpo-phalangeal and interphalangeal
articulations.

They are glnghjmo-arthrodlal^ connected by tiro lateral liga-
ments and an anterior Jihro-cartllage, or glenoid ligament^
except for the thumb, where this is replaced by two sesamoid
bones, while behind an expansion of the extensor tendon and
some loose areolar tissue completes each little synovial capsule ;
nerves and arteries are from the digitals ; the Interphalangeal
joints resemble the metacarpo-phalangeal in regard to liga-
ments ; they are true hinge-joints (^glngli/mus).

The Articulations of the Lower Extremity.

Describe the hip-joint.

An enarthrodlal, but not so freely moving joint as that of
the shoulder ; it is formed by the head of the femur and the
acetabulum of the os innominatum ; the ligaments are (Fig. 81):

The cajw?</ar^, arising near to the acetabular margin, and
from the outer surface of the transverse ligament ; it is attached
to the femur in front to the trochanter major and spiral line,
and behind to the neck about half an inch from the posterior
intertrochanteric line ; it is thence reflected like a tube up to
the head of the femur. The capsule has accessory ligaments
from the three bones of the os innominatum, lllo-femoral, illo-
trochanterlc. pubo-femoral, ischio-capsular.

The illo-femoraP^ or Y-llgament, arising from the anterior infe-

ARTICULATIONS OF THE LOWER EXTREMITY. 133

rior iliac spine to be attached to the spiral line, the outer and
inner margins so well marked as to seem like distinct liga-
mentous bands showing the capsule between.

The Hgamentum terea^^, arising by separate heads from each
side of the cotyloid notch externally, passes beneath the trans-
verse ligament rising from it and the fossa acetabuli covered
by the synovial membrane, and is attached to the fossa capitis
of the femur.

Cotyloid, a marginal fibro-cartilage attached all around the
acetabular margin, forms the transverse ligament below, deepen-
ino- the socket.

Transverse, is a ligamentous band of the cotyloid bridging
the cotyloid notch, converting it into a foramen ; nerves, from
the anterior crural by branch to rectus, obturator, accessory
obturator, nerve to the quadratus femoris, great sciatic or

Fig. 81.— Hip-joints, anterior view.

lower part of the sacral plexus ; arteries, internal and external
circumflex, obturator, gluteal, and sciatic. The synovial mem-
brane commonly communicates with the bursa beneath the
ilio-psoas muscle.

Describe the knee-joint.

(iinffJymoid, formed by condyles of the femur, upper surface
of the tibial head, and patella, it has the largest synovial sac o^

134 ESSENTIALS OF HUMAN ANATOMY.

any joint, sending a prolongation beneath the popliteus muscle
and another two or three inches up the front of the femur,
beneath the quadriceps tendon, the snhcrural bursa or pouch;
the bursa between the semimembranosus and internal head of
the gastrocnemius and inner condyle usually communicates
with the joint, and often one or more of the remaining bursae
near the articulation ; its ligaments consist of

An anterior or ligamentum patdla:,^ (Fig. 83), a continuation
of the quadriceps tendon attached to the tubercle of the tibia
below, which, wn'th the fibrous hood formed by the two vasti
tendons attached to the patellar margins and the oblique lines
on the head of the tibia extending upward from the tubercle,
cover in the joint in front blending with the lateral ligaments.

The posterior or ligamentum ]yinslowii^j formed of dense,
interlacing fibers, having incorporated with it part of the semi-
membranosus tendon ^ (Fig. 82), extends from the femur to the
tibia and from the external to the internal lateral ligaments.
The popliteal oblique ligament passes from the back part of the
inner tuberosity of the tibia, connected with the semimem-
branosus upward and outward, within the intercondyloid notch,
to the back part of the external condyle of the femur. The
ligamentum arcuatum is sometimes present below the oblique
ligament convex inferiorly.

The internal lateral^, a strong flat band passing from the
depression on the inner femoral epicondyle to the inner border
and surface of the shaft of the tibia for two or three inches
(5—8 cm.) below the articular surface; it is attached to the
internal semilunar fibro-cartilage.

The external lateral ligaments are two in number :

The long^^ a rounded cord attached above to external epi-
condyle of the femur, below to the outer part of the head of
the fibula, splitting the tendon of the biceps ;

The sliort^ behind and parallel to the above, attached above
to the lower part of the outer femoral condyle, below to the
summit of the styloid process of the fibula ; it joins the
arcuate above when that is present. All the preceding liga-
ments are accessory to and strengthen the

Capsular ligament, within which are the internal liaauients
(Fig. 83).

The anterior crucial-, from the inner side of the depression
in front of the spine of the tibia, passes upward, backward, and

ARTICULATIONS OF THE LOWER EXTREMITY. 135

outward to the inner siirikce of the back part of the outer con-
dyle of the femur.

The posterior crucial \ from back part of the depression
behind the tibial spine and popliteal notch to the outer fore
part of the inner condyle— both crucial ligaments are attached
to the respective extremities of the external semilunar fibro-

FiG 82.— Riffht knee-joint, posterior Fig. 8.3.— Right knee-joint show-
view. (Leidy.) ing internal ligaments.

cartilage. The tibers from the external cartilage to the poste-
rior crucial are called the third crucial or ligament of Wrisberg.

Tiro semilunar Jiljro-carfilageH\\ attached by the extremities
to the depressions in front and behind the spine of the tibia ;
they serve to deepen the sockets for the femoral condyles, and
are attached to the head of the tibia by the coronary ligaments,
short bands passing between their outer margins and the tibial
head ; they are also connected to one another, in front, by the
small band-like fransrrrsc ligament *.

Stretching from the front of the joint, below the patella, to
the front of the intercondyloid notch, is the triangular fold of
the synovial membrane calltMl the ligamentum. miicosum, from
whose sides extend ujtward and outward to the sides of the
patella the fringe-like folds termed ligameuta alaria.

Nerves, internal and external poplitOMl. anterior crural, ob-

136 ESSENTIALS OF HUMAN ANATOMY.

turator ; arteries^ five articular from popliteal, aiiastomotica
magna from femoral, two recurrents from anterior tibial, ex-
ternal circumflex, and fourth perforating of profunda. The
InivHsc in relation to the joint are numerous : three prepatellar,
three pretibial, one subcrural, four placed externally and five
internally.

Describe the superior tibio-fibular articulation.

Arthrodial, formed between the facets on the fibular head
and outer tuberosity of the tibia, its ligaments are really a
ccq^side. described as

Anterior superior tthw-jihular ^° (F^g- S*^)? directed obliquely
upward and inward from the fibula to the tibia.

Posterior superior tibio-jihular ^^ (Fig. 82), similarly disposed
behind ; the synovial membrane communicates with that of the
knee in one out of eighty specimens ; nerves, from the external
popliteal ; arteries, inferior external articular, anterior and
posterior tibial recurrent.

Describe the so-called middle tibio-fibular articulation.

The contiguous borders of the bones are connected by the
interosseous memhrane^^ (Fig. 88), deficient above for the
passage of the anterior tibial vessels, below it is perforated by
the anterior peroneal vessels; its fibers pass from the tibia
downward and outward to the fibula.

Describe the inferior tibio-fibular joint.

Syndesmosis, like a suture, formed superiorly by the rough
surfaces of the contiguous bones, below by small cartilage-
coated surfaces ; its limited synovial membrane is part of that
of the ankle.

The ligaments are :

Inferior interosseons, which is really part of the interosseous
membrane, passing between the rough surfaces of the two
bones.

Anterior and posterior inferior tihio-Jihidar, oblique fibrous
bands binding together the contiguous bony surfaces in front
and behind.

Transverse, a narrow band passing from the external malle-
olus to the tibia behind the joint; nerves, those of the ankle;
arteries, anterior and posterior peroneal and external malleolar.

ARTICULATIONS OF THE LOWER EXTREMITY. 137

Describe the ankle-joint.

Guiglymoid, formed by the lower end of the tibia with its
malleolus and the external malleolus, and the upper surface
and sides of the astragalus ; its ligaments are the

Anterior'* (Fig- 8-1), connecting the articular margins of the
tibia and fibula with the rough upper surface of the astragalus.

Posterior'^ (Fig- 84), thin and imperfect, extends between

Fig. 84.— Right ankle-joint, in-
ternal view.

(Leidy.)

Fig. 85.— Right ankle-joint, ex-
ternal view.

the external malleolus, lower end of the tibia and posterior tibio-
fibular ligament above ; below, to the posterior surface of the
astragalus from one lateral ligament to the other.

Interned lateral^ (Fig- 84), (deltoid) radiates from the lower
border of the inner malleolus to the astragalus behind, in front
to the navicular, and between to the os calcis. It has a deep
set of fibers from the malleolus to the astragalus.

External lateral'^^^ (Fig. 85), composed of three fa.sciculi
from the anterior margin, apex, and back of the external mal-
leolus; it is attached to the astragalus and the os calcis ; nerves,
internal saphenous, anterior and posterior tibial ; arteries, ante-
rior and posterior tibial, anterior and posterior peroneal.

Describe the tarsal joints.

Those of the first rcnv are arthrodial ; the astragalus and
calcis have three ligaments:

ErJernal rdlcaneo-astrnrfdloid, from the outer surface of the
astragalus to the outer surface of the calcis.

The posterior calcaneo-astraffaloid connects the posterior tu-
bercle of the astragalus with the upper surface of the calcis.

138 ESSENTIALS OF HUMAN ANATOMY.

The internal caJcaneo-astragahtid connects the back of the
astragalus to the sustentaculum tali.

The interosseous, the chief bond, filling up the groove on the
under surface of the astragalus and upper one of the calcis ;
there are two synovial sacs, one posterior, the other anterior,
continued between the astragalus and navicular ; nerves, poste-
rior tibial or plantar; arteries, posterior tibial, tarsal, external
malleolar (from anterior tibial), and terminal twigs of the
peroneal.

Joints of the second row, navicular, cuboid, and cuneiforms,
have

Dorsal ligaments, small bands connecting the contiguous
bones, and

Plantar ligaments, similarly disposed ; also four

Interosseous ligaments, connecting the sides of the navicular
and cuboid, the internal and middle cuneiform, the middle and
external cuneiform, the external cuneiform and cuboid; nerves,
anterior tibial, internal and external plantar ; arteries, meta-
tarsal and plantars.

Joints between the two rows, or medio-tarsal : (1) The cal-
caneo-cuhoid, artltrodial, has

The superior calcaneo-cuhoid ligament, connecting the dorsal
surfaces of the calcis and cuboid.

The internal (^interosseous) calcaneo-euhoid, connecting the
inner part of the front of the calcis with the postero-internal
angle and contiguous part of the cuboid.

The long calcaneo-cuhoid (plantar) arises from the under
surface of the calcis between the posterior tubercles and the
anterior tubercle, to be attached to the oblique ridge of the
cuboid and bases of the second, third, fourth, and fifth meta-
tarsal bones, completing a canal for the long peroneal tendon.

The short plantar arises from the anterior calcaneal tubercle
and the bone in front, to be attached to the under surface
of the cuboid behind the ridge, except at the outer angle ;
the synovial sac is distinct from that of the other tarsal
joints.

(2) The astragalo-navicula r articulation is the only enarthro-
dial (ball-and-socket) joint of the tarsus; its only ligament is
th'3 superior astragalo-navicular.

The ligaments connecting the os calcis and navicular are

The superior calca nco-navicular , dense and thick, extending

ARTICULATIONS OF THE LOWER EXTREMITY. 139

from the anterior iiiternal extremity of the calcis to the outer
surface of the navicular.

The inferior cdlcanco-iuiviciflar, passing ol)liquely forward
from the sustentaculum tali to the under surface of the navic-
ular ; nerves of the medio-tarsal joint are the external branch
of the anterior tibial, sometimes the musculo-cutaneous or
external plantar; arteries, anterior tibial, tarsal, metatarsal,
external, and internal plantar.

Describe the tarso -metatarsal articulations.

ArtJiro(/i(/l, between the three cuneiforms and the cuboid,
and the bases of the five metatarsals ; their ligaments are :

Dorsal, one between the first metatarsal and internal cunei-
form ; one from each cuneiform to the second ; one each from
the external cuneiform to the third and fourth ; one each from
the cuboid to the fourth and fifth metatarsals.

Plantar, more irregularly disposed ligamentous fibers.

Interosseous, one connecting the outer extremity of the inner
cuneiform to the adjacent angle of the second metatarsal ; one
between the outer cuneiform and the adjacent angle of the sec-
ond metatarsal; one connecting the outer angle of the external
cuneiform with side of the third metatarsal ; nerves, anterior
tibial and plantars ; a7-teries, from the dorsalis y)edis })y the
metatarsal, deep plantar arch, and internal plantar.

Describe the articulations of the metatarsal bones with each
other.
Except the first, their bases are bound together by tlx; dor-
sal, plantar, anil interosseous ligaments; tlie distal extremities
are united by the deep transverse metatarsal ligament.

Describe the metatarso-phalangeal and the interphalangeal
articulations.

They resem})le in all respects tliose of the liand (which see).

How many distinct synovial sacs have the tarsus and the
metatarsus ?
Six, viz.: (1) between the calcis and the astragalus, poste-
rior to the inteross(!OUH ligament; (2) in front of the same
ligament, between the calcis and the astragalus, also betwcsen
the astragalus and navicular; (8) between the calcis and the
cuboid ; (\) })etween th(! navicular, cuboid, nnd the cuneiforms.

140 ESSENTIALS OF HUMAN ANATOMY.

communicating between tlie middle and the external cunei-
forms with the joints formed between those bones and the bases
of the second and third metatarsals ; (5) between the sides
and bases of the fourth and fifth metatarsals and the cuboid ;
(()) between the base of the first metatarsal and the internal
cuneiform.

MUSCLES AND FASCI/E.

What is a muscle ?

It is a structure connected with bones, cartilages, ligaments,
or skin, directly or through the medium of a tendon or apo-
neurosis ; the structure is capable of shortening when irritated
mechanically or by nerve-stimulus, this property being called
muscular coatractUity or irritahiHty.

How are muscles divided?

According to their form, into narrow, broad, penniform (when
their fibers converge like the plumes of a pen to one side of the
tendon) ; hipenniform when so arranged on both sides of a ten-
don, radiated; also named from situation, direction, use, size,
or attachments.

What are the varieties of muscular tissue ?

There are two^ one variety consisting of prismatic fasciculi
about 4^oth of an inch in diameter, marked by transverse
striae, each bundle surrounded by a sheath ov perimysium ; each
fasciculus is formed of a number of Jihrillse,, Ts^io^o^^^ ^^ ^" '\i\Qh.
in diameter, surrounded by a tubular, transparent elastic mem-
branous sarcolemma. Every fibril presents alternating dark
and light zones ; the former is the frausverse disk ; in its center
is a transverse lighter band, Flensen's line. The light zone is
divided into two lateral disks by a dark line called the inter-
mediate disk, or Kranse's memhrane. A sarcous element of Bow-
man is the part included between two lines of Krause. This
variety of tissue forms the vohiutary, striped mnscles, or those
of animal life, being under the control of the will ; the invol-
untary, nnstripcd, or the muscles of organic life, are not under
the control of the will, and consist of elongated, spindle-shaped,
flattened, nucleated cells, R-Jo^th to gj^th of an inch long,
-j^T^j-Qth to Tj ^Q^th broad, and are held together in bundles by a
cement-substance containing a few connective-tissue corpuscles,

MUSCLES AND FASCIA. 141

the bundles being further collected into larger fasciculi, or
flattened bands, bound together by ordinary areolar tissue ; this
kind of muscle is that found forming the contractile coats of
the stomach, intestines, bladder, arteries, veins, lymphatics,
ureters, urethra, iris, ciliary body, etc. ; when irritated a part
contracts and slowly relaxes, while another contiguous portion
is contracting, which action being continued produces the
vermicular (worm-like), peristaltic movements of the intestines.
The spontaneously coagulable albuminous substance composing
muscle is called myoi^in ; so-called ayntonin is a modification
produced by chemical agents.

What are tendons and aponeuroses ?

Tendons are glistening cords or bands, of white inelastic
fibrous tissue, almost without blood- or nerve-supply, and con-
nect the muscular tissue with the part to be moved ; aponeu-
roses are membranous expansions of the same tissue serving
similar purposes.

What are the fasciae?

They are laminae of fibrous or fibro-areolar tissue investing
the soft tissues ; the superficial fascic^- are usually fibro-areolar,
lie beneath the skin, and are loaded with fat ; the deep fasciaB
resemble aponeuroses, are dense and inelastic, ensheathing mus-
cles, or serving for their attachment, and tend to preserve the
form of the part, since partitions descend between various mus-
cles to become attached to the periosteum of the osseous frame-
work.

To what are the tendons attached?

To the periosteum and perichondrium with which they
become blended, to the subcutaneous tissue, and to ligaments.

What are meant by the origin and the insertion of a muscle ?
The orupn is the most fixed and central point from which the
muscle acts ; the insertion is the movable point to which the
muscular force is directed ; but in many muscular acts the
part usually described as the insertion becomes the fixed point,
and the oriuin the movable one. Some muscles have double
origins and single insertions, as the occipito-frontalis, digastric,
or omo-hyoid.

142 ESSENTIALS OF HUMAN ANATOMY.

Muscles of the Head.

Describe the origin, insertion, action, and nerve-supply of
the following muscles (Fig. 86j.

The facial nerve supplies motion to all the muscles of ex-
pression ; the inferior maxillary division of the fifth, to all
muscles of mastication except the buccinator.

Occipito-frontalis ^ : origin^ occijntal portion, outer two-thirds
of the superior curved line of the occipital bone and mastoid
process, insertion into the epicranial aponeurosis ; frontal por-
tion rises from the epicranial aponeurosis and blends below with
the eyebrow, continuous with the pyramidalis nasi, interlacing
with the corrugator supercilii and orbicularis palpebrarum ;
action, raises the eyebrows and transversely wrinkles forehead;
nerves, facial, by its posterior auricular and temporal branches.

Attolens aurem*: origin, epicranial aponeurosis; insertion,
superior portion of the pinna of the ear ; action, raises the
pinna ; nerve, temporal branch of the facial.

Atrahens aurem: origin, lateral margin of the epicranial
aponeurosis ; insertion, a projection on front of the helix ;
action, draws the pinna forward and upward ; nerve, facial.

Retrahens aurem ^: origin, mastoid portion of the temporal
bone ; insertion, lower part of the concha ; action, draws ear
backward ; nerve, posterior auricular branch of the facial.

Orbicularis palpebrarum "^ : origin, internal angular process of
the frontal, nasal process of the superior maxillary bone, and the
anterior surface and margins of the tarsal ligaments ; insertion,
skin of the eyelids and contiguous portions of the forehead,
temple, and cheek, blending with the occipito-frontalis and
corrugator supercilii muscles; action, closes eyelids; nerve,
facial.

Corrugator supercilii: origin, inner end of the superciliary
ridge ; insertion, upward and outward to the under surface of the
orbicularis palpebrarum ; action, draws the eyebrow downward
and inward ; nerve, facial.

Tensor tarsi (Horner's muscle) : origin, crest of the lacrimal
bone ; insertion, by two slips into the tarsal cartilages near the
puncta ; action, compresses the lacrimal sac and keeps the
puncta in contact with the globe ; nerve, facial. (For occu-
lar muscles, see p. 355.)

Levator palpebrae superioris^: origin, lesser wing of the sphe-

MUSCLES OF THE HEAD.

143

noid ; insertion, upper border of the superior tarsal cartilage
and into the skin ; action, elevates the upper lid ; nerve, third
cranial (motor oculi).

Fig. 86.— Muscles of the head, face, and neck (Leidy).

Pyramidalis nasi "^ : origin, occipito-frontalis ; insertion, into
the compressor naris ; action, depresses the inner angle of the
eyebrow ; nerve, facial.

Levator labii superioris alseque nasi ^ : origin, upper part of the
nasal process of the superior maxillary bone ; insertion, the
cartilage of the ala of the nose, and into the upper lip blending
with the orbicularis and levator labii ; action, draws upward
the upper lip and dilates the nostril ; nerve, facial.

Dilator naris anterior: origin, cartilage of the ala; insertion,
integument near its margin ; action, dilates the nostril ; nerve,
facial.

Dilator naris posterior: origin, margin of the nasal notch of
the superior maxilhi and the sesamoid cartilages; insertion,

144 ESSENTIALS OF HUMAN ANATOMY.

skin near the margin of the nostril; action^ dilates the nos-
tril ; nerve, facial.

Compressor nasi'': oritjiii^ above and external to the incisive
fossa of the superior maxilla ; fnf;erfion, fibro-cartilage of the
nose, and is continuous with its fellow and the aponeurosis of
the pyramidalis nasi; r^c^^V>;^ depresses cartilage, compresses
alee, dilates nostril, and wrinkles skin; nerve, facial.

Compressor narium minor : origin, alar cartilage ; insertion,
skin of tip of the nose; action, dilates the nostril; nerve,
facial.

Depressor alse nasi : origin, incisive fossa of the superior
maxilla ; insertion, septum and back part of the ala ; action,
narrows the nostril ; nerve, facial.

Levator labii superioris ^ : origin, lower margin of the orbit
above the infraorbital foramen ; insertion, muscular substance
of the upper lip ; action, elevates the lip ; nerve, facial.

Levator anguli oris ^^ : origin, canine fossa of the superior
maxilla ; insertion, angle of the mouth ; action, elevates angle of
the mouth ; nerve, facial.

Zygomaticus major ^^ : origin, malar bone; insertion, angle of
the mouth : action, elevates angle of the lip ; nerve, facial.

Zygomaticus minor '^ (inconstant): origin, malar bone ante-
riorh^ ; insertion, angle of the mouth; action, same as major;
nerve, facial.

Levator labii inferioris (levator menti) : origin, incisive fossa
of the lower jaw ; insertion, skin of the chin ; action, elevates
the chin and the lower lip ; nerve, facial.

Depressor labii inferioris ^^'^ (quadratus menti): origin, ex-
ternal oblique line of the lower jaw ; insertion, skin of the
lower lip; action, depresses the lower lip; ?ie?'?;e. facial.

Depressor anguli oris ^* : origin, external oblique line of the
lower jaw ; insertion, angle of the mouth ; action, depresses
angle of the mouth ; nerve, facial.

Orbicularis oris ^^ : origin, nasal septum and superior and in-
ferior maxillary borders by accessory fibers called accessorii
orbicularis superioi'is and inferioris, and naso-lahialis ; insertion,
the buccinator and other muscles converging to the mouth ;
action, closes the mouth ; nerve, facial.

Buccinator '=«: origin, behind, from the pterygo-maxillary liga-
ment, above and below the external surfaces of the alveolar
processes of the three molar teeth ; insertion^ orbicularis oris ;

MUSCLES OF THE NECK. 145

action^ compresses the cheek ; nerve, facial and buccal branch
of the inferior maxillary, the latter being sensory.

Risorius (Santorini) : origin, fascia over the masseter muscle-
insertion, skin at angle of the mouth ; action, laughing muscle ;
nerve, facial.

Masseter 1-: origin, the superficial portion from the malar
process of the superior maxilla and the anterior two-thirds of
the lower border of the zygomatic arch, the deep portion from
the posterior third of the lower border and the inner surface
of the zygomatic arch; insertion, into the outer surface of the
ramus, angle, and coronoid process of the lower jaw ; action,
raises, protracts, and retracts the lower jaw, a masticatory
muscle ; nerve, inferior maxillary.

Temporal: origin, temporal fossa and fascia; insertion, into
anterior border, apex, and inner surface of the coronoid process
of the lower jaw ; action, raises and retracts the lower jaw, a
muscle of mastication ; nerve, inferior maxillary.

Internal pterygoid: origin, by two heads from the inner surface
of the external pterygoid plate and grooved surface of the pal-
ate bone, and by a second slip from the tuberosity of the palate
and superior maxillary bones; insertion, lower back part of the
inner side of the ramus and angle of the jaw as high as the
dental foramen ; action, raises and draws the lower jaw for-
ward, a muscle of mastication ; nerve, inferior maxillary.

External pterygoid: origin, by two heads, one from the infra-
temporal ridge on the greater wung of the sphenoid, and from the
bone included between it and the base of the pterygoid process,
the other from the outer surface of the external pterygoid plate ;
insertion, depression in front of the neck of the condyle of the
lower jaw and interarticular fibro-cartilage ; action, depresses
and draws the jaw forward, a triturating masticatory muscle ;
nerve, inferior maxillary. Usually the internal maxillary artery
passes between the two heads of this muscle : sometimes pierces
it ; often lies below it.

Muscles of the Neck.

Platysma myoides : origin, deep fascia over the pectoral, deltoid,
sterno-niastoid, and trapezius muscles; insertion, lower jaw be-
neath the oblirjue line, angle of the mouth, cellular tissue, and
some muscles of the face; ac^<o?<, wrinkles skin of the neck and
10

146

ESSENTIALS OF HUMAN ANATOMY.

depresses the jaw and angle of the mouth ; iicj-ccs, facial, by
the inframaxillary branches.

Sterno-cleido-mastoid " (Fig. 87): origin, upper front part of

Fig. 87. — Muscles of the neck, anterior view (Leidy).

the sternum, inner third of upper border of the clavicle; inser-
tion, mastoid process of the temporal and outer two-thirds of the
superior curved line of the occipital bone ; action, acting sinffb/,
flexes head sideways, and rotates chin to the opposite side, both
actins: flex the head on the neck, and the neck on the chest ;
nerves, spinal accessory, second and third cervical nerves, ante-
rior branches.

Sterno-hyoidi^: origin, ribbon-like, from the posterior surface
of the sternum and inner end of the clavicle ; insertion, body
of the hyoid bone ;. action, depresses the hyoid bone ; nerves,
filaments from the loop between the descendens and the com-
municans cervicalis.

Sterno-thyroid'': origin, posterior surface of the sternum and
cartilage of the first rib, sotiietimes from the clavicle ; i^iser-
tion, oblique line on the ala of the thyroid cartilage ; action,
depresses the larynx ; nerves, same as the sterno-h3^oid.

Thyro-hyoid'*': origin, oblique line of the thyroid cartilage;
insertion, lower border of the body and greater cornu of the

MUSCLES OF THE NP]CK. 147

hyoid bone ; action^ may elevate the larynx or depress the
hyoid ; iwrvc^ descendens cervicalis.

Omo-hyoid'^: orighi^ from the upper border of the scapula
near the suprascapular notch, perhaps, also, from the trans-
verse ligament ; insertion^ body of the hyoid bone, its central
tcnduioiis imrtloii being held down by a process of the deep
cervical fascia prolonged down to be attached to the cartilage
of the first rib ; action^ depresses the hyoid bone and larynx,
and draws them backward to one or the other side ; nerves, from
the loop between the descendens and the communicans cervi-
calis.

Digastric'- 2; origin, has two fleshy bellies with an interme-
diate rounded tendon, the posterior' is attached to the digas-
tric groove of the mastoid process of the temporal, the ante-
rior^ to the depression on the inner side of the lower border of
the jaw near the symphysis ; insertion, tendon perforates the
stylo-hyoid, and is held to the side of the body and greater
cornu of the hyoid bone by an aponeurotic loop lined with
synovial membrane ; action, raises the hyoid bone ; if this be
fixed by its muscles, depresses the lower jaw ; nerves, posterior
belly by the facial, anterior by the mylo-hyoid branch of the
inferior dental. ^

Stylo-hyoid*: origin, middle of the outer surface of the sty-
loid process of the temporal ; insertion, body of the hyoid at its
junction with the greater cornu ; it is perforated by the digas-
tric tendon; action, same as the posterior belly of the digastric;
nerve, facial.

Mylo-hyoid^: onym, mylo-hyoid ridge of the lower jaw; in-
sertion, body of the hyoid bone and median raphe; action,
same as the digastric and stylo-hyoid ; nerve, mylo-hyoid branch
of the inferior dental ; it forms with its fellow the muscular
floor of the mouth.

Genio-hyoid''': origin, inferior genial tubercle of the lower jaw ;
insertion, body of the hyoid bone ; action, same as the digastric;
nerve, descendens cervicalis.

Genio-hyo-glossus^: origin, superior genial tubercle of the
lower jaw ; insertion, body of the hyoid bone, side of the
pharynx, and tongue from the base to apex ; action, protrudes
the tongue by the posterior and inferior fibers, retracts it by the
anterior fibers, both muscles acting render tongue concave from
side to side, as in sucking ; nerve, hypoglossal.

148 ESSENTIALS OF HUMAN ANATOMY.

Hyo-glossus^: oriyiii, body, lesser, and wliole length of the
greater cornu of the hyoid bone ; insertion^ side of the tongue ;
the parts niay be called /x/.s/o-, choudrtf-^ and licnifo-yhjusas ;
action^ draws down the sides of the tongue, making it convex ;
nerve ^ hypoglossal.

Stylo-glossus ■* : origin^ near the center of the antero-external
surface of the styloid process and stylo-maxillary ligament ;
insertion^ side of the tongue and hyo-glossus muscle ; action.,
draws the tongue upward and backward ; nerve., hypo-
glossal.

Lingualis forms the bulk of the tongue lying between the
hyo-glossus and genio-hyo-glossus on each side ; it has four sets
of fibers, superior., inferior., transverse^ and vertical lingualis.

Palatal Region.

Levator palati: origin^ under surface of the apex of the pe-
trous portion of the temporal bone and contiguous portion of the
cartilaginous Eustachian tube ; insertion., into the posterior sur-
face of the soft palate ; action, elevates the soft palate ; nerve
was said to be facial ; it is probably the spinal accessory through
the pharyngeal plexus.

Tensor palati: origin., scaphoid fossa, outer side of the Eus-
tachian tube, spine of the sphenoid, edge of the tympanic plate :
insertion., after reflection around the hamular process, into the
forepart of the aponeurosis of the soft palate and the under
surface of the palate bone; action, renders the soft palate tense;
nerve, branch from the otic ganglion.

Azygos uvulae: origin, posterior nasal spine and palatal apo-
neurosis ; insertion, uvula ; action, raises the uvula ; nerve, same
as for the levator palati ; it is not a single muscle, as the name
implies.

Palato-glossus (anterior pillar of fauces): origin, anterior sur-
face of the soft palate external to the uvula ; insertion, side and
dorsum of the tongue ; action, as one of its names implies, con-
strictor isthmi faucium ; nerve, spinal accessory through the
pharyngeal plexus.

Palato-pharyngeus (posterior pillar of fauces ) : origin, soft
palate ; insertion, posterior border of the thyroid cartilage and
side of the pharynx ; action, closes the posterior fauces; nerve,
same as for the palato-glossus.

VERTEBRAL REGION. 149

Vertebral Region.

Rectus capitis anticus major: origui, by four tendinous slips
from the anterior tubercles of the transverse processes of the
third, fourth, fifth, and sixth cervical vertebrae ; msertio)i, bas-
ilar process of the occipital bone; action, flexes the head and
slightly rotates; nerves, suboccipital, and from a loop formed
by it and the second cervical.

Rectus capitis anticus minor : origin, front of the lateral mass
of the atlas and root of its transverse process ; insertion, basilar
process of the occipital bone behind the preceding muscle ; ac-
tion, flexes the head ; nerve, suboccipital.

Rectus lateralis : origin, upper surface of the transverse
process of the atlas; insertion, jugular process of the occipital
bone ; action, draws the head laterally when one acts, flexes
when both act ; nerve, suboccipital. These muscles belong to
the series of intertransverse muscles.

Longus colli: origin, superior oblique jjortion from the ante-
rior transverse tubercles of the third, fourth, and fifth cervical
vertebrae ; insertion, tubercle on the anterior arch of the atlas ;
the inferior oblique portion arises from the bodies of the first two
or three thoracic vertebrae, insertion, transverse processes of
the fifth and sixth cervical vertebrae ; vertical portion extends
between the bodies of the three upper thoracic and three lower
cervical, and those of the second, third, and fourth cervical
vertebrae ; action, flexes and slightly rotates the cervical
spine ; nerves, anterior branches from the lower cervical
nerves.

Scalenus anticus'" (Fig. 87) : origin, anterior tubercles of the
transverse processes of the third, fourth, fifth, and sixth cer-
vical vertebrae ; insertion, tubercle on the upper surface of the
first rib; action, lateral flexion of the cervical spine or eleva-
tion of the ribs ; nerves, anterior branches of the fourth, fifth,
and sixth cervical nerves before the plexus is made.

Scalenus medius ^' : origin, posterior tubercles of the trans-
verse processes of the six lower cervical vertebne ; insertion,
upper surface of the first rib behind the; subclavian groove ;
«c;/Vy/?, similar to the preceding; nerves, anteri(»r branches from
the cervical.

Scalenus posticus : origin, posterior tubercles of the two or
three lower cervical vertebrae ; insertion, outer surface of the

150 ESSENTIALS OF HUMAN ANATOMY.

second rib ; action, flexes neck laterally, or elevates the second
rib ; nerves, anterior branches from the three lower cervical.

Muscles of the Back.

first layer (Fig. 88):

Trapezius ' : origin, inner third of the superior curved line of
the occipital bone, ligamentum nuchas, spinous processes of the
seventh cervical and of all the thoracic vertebrae, and correspond-
ing portion of the supraspinous ligament ; insertion, outer third
of the posterior border and upper surface of the clavicle, inner
margin of the acromion process, the superior lip of the crest of
the spine of scapula, and the tubercle at its inner extremity ;
action, one acting draws the head to its own side, both acting draw
the head backward, and with the head fixed elevate the point
of the shoulder ; middle and lower fibers partially rotate the
scapula on the chest ; nerves, spinal accessory, third and fourth
cervical from anterior divisions.

Ligamentum nuclise (a thin band of condensed cellulo-fibrous
membrane): c»r/^/«, external occipital protuberance; insertion,
spinous processes of all the cervical vertebrae except the atlas ;
a rudiment of a strong elastic ligament sustaining the head in
the lower animals.

Latissimus dorsi* : origin, by an aponeurosis from the spinous
processes of the six lower thoracic vertebras, those of the lumbar
and sacral vertebras and supraspinous ligament, also external lip
of the iliac crest behind the external oblique, from the three or
four lower ribs, and often from the inferior angle of the
scapula ; insertion, floor of the bicipital groove of the humerus ;
action, draws the humerus downward and backward while
rotating inward ; with fixed arms, raises the lower ribs in
forcible inspiration, assists the greater pectorals and the ab-
dominal muscles in drawing the trunk forward, as when climb-
ing, or using crutches, etc. ; nerve, long subscapular nerve.

Second layer:

Levator scapulae '° : origin, by three or four tendinous slips
from the posterior tubercles of the transverse processes of the
three or four upper cervical vertebrae ; insertion, posterior bor-
der of the scapula between the superior angle and triangular
surface at the apex of the spine ; action, raises the scapular

MUSCLES OF THE BACK. 151

angle, extensor and lateral flexor of the neck ; nerves, from the
anterior divisions of the third, fourth, and fifth cervical.

Rhomboideus minor " : origin, ligamentuni nuchte, and spinous
processes of the seventh cervical and first thoracic vertebrae ;

Fig. 88.— Muscles of the back (Leidy).

insertion, margin of the triangular surface at the apex of the
spine of the scapula ; act ion, draws the inferior angle back-
ward and upward ; nerve, fifth cervical.

Rhomboideus major ''^ : origin, spinous processes of the four or

152 ESSENTIALS OP HUMAN ANATOMY.

five upper thoracic vertebrtnc and supraspinous ligament ; inser-
tion, tendinous arch stretched from the triangular surface at
the apex of the spine of the scapula to the inferior angle, the
arch being connected with the vertebral border by a thin
membrane ; action, draws the inferior angle backward and
upward ; nerve, fifth cervical.

Third layer:

Serratus posticus superior : origin^ by a thin aponeurosis from
the ligamentum nuchae and spinous processes of the seventh
cervical and two or three upper thoracic vcrtebme and the
supraspinous ligament; insfrrtion, by fleshy digitations into the
upper borders of the second, third, fourth, and fifth ribs a lit-
tle beyond their angles ; action, elevates the ribs during in-
spiration ; nerves, branches of the upper intercostals.

Serratus posticus inferior"': origin, by a thin aponeurosis
from the spinous processes of the two last thoracic and two
or three upper lumbar vertebme and supraspinous ligament ;
insertion, by four digitations into the lower borders of the four
lower ribs, beyond their angles ; except the last rib, which has
no angle ; action, depresses the ribs in expiration ; nerves,
branches of the lower intercostal nerves.

Splenius capitis et colli ^^' ^* : origin, tendinous from the lower
half of the ligamentum nuchae, the spinous processes of the
last cervical and of the six upper thoracic vertebrae, and supra-
spinous ligament; insertion (S. capitis^^), mastoid process and
rough surface beneath the superior curved line of the occipital
bone ; (S. colli^*), posterior tubercles of the transverse processes
of the two or three upper cervical vertebrae ; action, together,
draw the head directly backward, singly, flex the head laterally
and slightly rotate it to the same side ; nerves, external poste-
rior branches of the spinal nerves, the cervical and thoracic.

Fourth layer :

Erector spinas '• '■ ^' *■ ^' '^ (Fig. 89) : origin, the sacro-iliac
groove, the anterior surface of the lumbo-sacral tendon, which
is attached internally to the spines of the sacrum, the spinous
processes of the lumbar and three lower thoracic vertebrae and
supraspinous ligament externally, the back part of the inner lip
of the iliac crest, with the rudimentary transverse processes

MUSCLES OF THE BACK.

153

of the sacrum and great sacro-sciatic ligament; this muscle oppo-
site the last rib divides into the ilio-costalis and longissiraus
dorsi muscles ; action, maintains the spine erect and bends the
body backward ; nerves, external posterior branches of the
lumbar and thoracic nerves.

Ilio-costalis '' - : origin, is part of the erector spina? ; insertion, by
six or seven tendons into the angles of the sixth to the eleventh
and border of the twelfth ribs ;
action, same as the erector spinae;
nerves, same as the erector spinge.

Musculus accessorius ad ilio-cos-
talem : origin, by flattened tendons
from angles of the seventh to the
eleventh and back of the last rib ;
insertion, angles of the six upper
ribs ; action and nerves, same as the
erector spinas.

Cervicalis ascendens: orv^i??, backs
of four or five upper ribs ; insertion,
posterior tubercles of the trans-
verse processes of the fourth,
fifth, and sixth cervical vertebrae ;
action, keeps the neck erect ;
nerves, external posterior branches
of the cervical and thoracic nerves.

Longissimus dorsi ^: origin, is
part of the erector spinae ; inser-
tion, posterior surface of the lum-
bar transverse processes and ac-
cessory tubercles of articular proc-
esses, tips of transverse processes
of all the thoracic vertebras, and
from the nine to the ten lowest ribs
between their tuberosities and an-
gles; action and nerves, same as
the erector sy»in;ie.

Transversalis colli'*'-': o/vV////, ten-
dinous from the summits of the . , . ,

, , . , Fio. 89.— Muscles of the back,

Six upper thoracic transverse pro- deep layers (Leidy).

cesses ; insertion, posterior tuber-
cles of the transverse processes from the second to the sixth

154 ESSENTIALS OF HUMAN ANATOMY.

cervical vertebra) ; action^ keeps the neck erect ; nerves^ exter-
nal posterior branches of the cervical and thoracic nerves.

Trachelo-mastoid ' : origin., by tendons from the transverse proc-
esses of the third, fourth, fifth, and sixth thoracic vertebra3 and
articular processes of the three or four lower cervical ; tuserfiou,
posterior margin of the mastoid process ; action, flexes the head
laterally ; nerves, external posterior branches of the cervical and
thoracic nerves.

Spinalis dorsi: origin, by tendons from the spinous proc-
esses of the two last thoracic and the first two lumbar ver-
tebrae ; insertion, by separate tendons into the spinous proc-
esses of from four to eight thoracic vertebrae ; action, erects
the spine ; nerves, external posterior branches of the thoracic
nerves.

Spinalis colli: origin, fifth, sixth, and seventh cervical spinous
processes, also sometimes those of the first and second thoracic
(this muscle is sometimes absent); insertion, spinous process
of the axis, occasionally those of the two vertebra3 below ;
action, extends the cervical spine ; nerves, external posterior
branches of the cervical nerves.

Complexus^: origin, by tendons from the tips of the transverse
processes oi the six or seven upper thoracic and seventh cervical
vertebras, and articular processes of the three cervical vertebrae
above this ; insertion, internally between the curved lines of the
occipital bone ; action, both draw the head backward, singly,
lateral flexion with rotation turning the face to the opposite
side ; nerves, internal posterior branches of the cervical, sub-
occipital, and great occipital (the hiventer cervicis, being usu-
ally blended with this muscle on its inner side, will receive no
separate description).

Fifth layer:

Semispinalis dorsi ^°: origin, by small tendons from the trans-
verse processes of the thoracic vertebrae, from the sixth to the
tenth inclusive; insertion, by five or six tendons, into the spi-
nous processes of the four upper thoracic and two lower cervical
vertebrae ; action, erects the spinal column ; nerves, internal
posterior branches of the thoracic nerves.

Semispinalis colli" : origin, tendinous and fleshy from the five
or six upper thoracic transverse processes ; insertion, second,
third, fourth, and fifth cervical spinous processes, the highest

MUSCLES OF THE BACK. 155

being the thickest ; action, erects the cervical spine ; nerves^ in-
ternal posterior branches of the cervical nerves.

Multifldus spinse "' : ur'ujiii^ back of the sacrum, aponeurosis of
the erector spinas (sacral region) ; posterior superior iliac spine,
posterior sacro-iliac ligaments (sacro-iliac region) ; mammil-
lary processes (lumbar region) ; transverse processes (thoracic
region) ; articular processes (four lower cervical vertebrae) ; in-
sertion^ spinous process of the third or fourth vertebra above
(most superficial), second or third above (middle layer) ; two
contiguous vertebrae (deepest layer) ; it extends i'rom the last
lumbar to the axis ; keeps the spine erect and rotates it ; nerves,
internal posterior branches of the cervical, thoracic, lumbar, and
sacral nerves.

Rotatores spinas (eleven pairs in the thoracic region only) :
origin each from the upper back part of the transverse proc-
ess ; insertion, lower outer part of the lamina of the vertebra
above ; action, as name implies ; nerves, internal posterior
thoracic branches.

Interspinales : origin, variable in number, there are usually six
cervical pairs commencing between the apices of the second and
third spinous processes ; two, occasionally three thoracic pairs,
between the first and second, eleventh and twelfth, sometimes
second and third vertebrae ; four lumbar pairs ; sometimes a
pair between the last thoracic and the first lumbar, and the fifth
lumbar and sacrum; (yc/ />>/?, extend the spine ; nerves, internal
posterior nerves of the regions.

Extensor coccygis is rarely found : origin, last bone of the
sacrum, or first of the coccyx ; insertion, lower part of the
coccyx, behind ; action, as named ; nerves, posterior divisions
of tlie fourth and fifth sacral and coccygeal.

Intertransversales''' : origin and insertion, double muscles be-
tween the anterior and the posterior tubercles of the trans-
verse processes in the cervical, occupy the intertransverse
spaces in other regions (three or four thoracic and four lum-
bar) ; action, lateral flexion singly, steady spine when both
sidi's act; verves, posterior spinal branches of each region.

Rectus capitis posticus major'': origin, spinous process of the
axis; insertion, inferior curved line of the occipital bone and
the surface below ; rotates and extends the head ; nerve, sub-
occipital.

Rectus capitis posticus minor ''^: origin, tub(!rcle on the poste-

15(5 ESSENTIALS OF HUMAN ANATOMY.

rior arch of the atlas; insertiou, rouuli .surface beneath the in-
ferior curved line, internal to the major, nearly as far as the
foramen maunum ; <ictio}i^ extends the head ; nerce, suboccipi-
tal.

Obliquus capitis inferior''^: origin^ apex of the spinous process
of the axis ; uis( rtion^ lower and back part of the transverse
process of the atlas; action^ rotates the atlas and head; nerve.,
suboccipital.

Obliquus capitis superior'^: origin^ tendinous from the upper
part of the transverse process of the atlas; insert ion., between
the curved lines of the occipital bone external to the com-
plexus ; action., extends the head, flexes laterally ; nerve, sub-
occipital.

Muscles of the Abdomen.

External oblique''' (Fig. DO) : origin, by eight fleshy digitations
from the external surface and lower borders of the eight infe-
rior ribs; in.sertion, anterior half of the outer lip of the iliac
crest, by an aponeurosis joining its fellow of the opposite side
it forms the lined alba, a median tendinous raphe, connected
above with the ensiform cartilage, below with the symphysis
pubis ; this aponeurosis is continuous above with the aponeu-
rosis of the pectoralis major, below it forms a broad infolded
band, continuous with the fascia lata, stretching from the an-
terior iliac spine to the pubic spine — /. e. Ponpart's ligament —
reflected from which, into the pectineal line, is a portion called
Ginihernaf's ligamenf ; above the crest of the os pubis is the tri-
angular external abdominal ring, its external border being Pou-
part's ligament, its inner, aponeurotic fibers, both called piUars
of the ring ; action, compresses the viscera, flexes the thorax on
the pelvis, or flexes the pelvis on the thorax, according to which
is the fixed point, also assists expiration ; nerves, lower inter-
cost als.

Internal oblique'^: origin, fleshy from the outer half of Pou-
part's ligament, anterior two-thirds of the middle lip of the iliac
crest, and posterior lamella of the lumbar fascia ; insertion, crest
and pectineal line of the os pubis with the transversalis muscle —
forming the conjoined tendon, a part of the posterior boundary
of the external abdominal ring — cartilages of the three lower
ribs, and by an aponeurosis, which splits for its upper three-
fourths to enclose the rectus muscle, into the linca alba ; the

MUSCLES OF THE ABDOMEN.

1

0(

anterior layer blends with the aponeurosis of the external ob-
lique, the posterior with that of the transversalis muscle, the
undivided lower fourth passing in irout of the rectus; action,

Fig. WJ.— Muscles of the thorax and the abdomen (Leidy).

same as the external oblique ; nerves, lower intercostals, ilio-
hypof^astrir*. arxl ilio-in<ininal.

Transversalis : oriyin, fleshy from the outer third of I'oupart's
li^amerjt, anterior three-fourths of the inner lip of the iliac crest,
inn(!r surface; of the six lower costal cartilages, and by a broad
apoiHMirosis, the InnilKtr J'dscin. from the lumbar transverse proc-

158 ESSENTIALS OF HUMAN ANATOMY.

esses ; inscrfion, with the internal oblique as the conjoined tendon
into the pubic crest and pectineal line, by its aponeurosis into
the linea alba, the upper three-fourths passing behind, the rectus
abdominis, the remainder in front of that muscle ; fiction and
nerves similar to the internal oblique.

Lumbar fascia : the vertebral aponeurosis of the transversalis
divides into an anterior thin layer attached to the front of the
lumbar transverse processes and to the lower margin of the last
rib, thus forming the ligeunentiim arcuatum cxferniun ; a middle,
stronger layer, attached to the apices of the transverse proc-
esses ; and a posterior layer attached to the apices of the
spinous processes ; the quadratus lumborum lies between the
anterior and the middle layers, the erector spinas between the
middle and the posterior ; the latter receives the attachment of
the internal oblique, and blended with the aponeuroses of the
serratus posticus inferior and latissimus dorsi forms the lumbar
fascia, consisting of three layers.

Rectus abdominis'^: origin, hy ivio tendons from the pubic
crest and ligaments over the symphysis pubis ; insertion, carti-
lages of the fifth, sixth, and seventh ribs; this muscle is
enclosed in a sheath, the upper three-fourths in front formed
by the aponeurosis of the external oblique and half of that of
the internal oblique, behind for the same extent the trans-
versalis aponeurosis with the posterior division of that of the
internal oblique ; at the lower fourth the aponeuroses of all
three muscles pass in fremt of the rectus ; three or four tendi-
nous intersections traverse the muscle called the linese trans-
versa, while the Iine?e semiJunares. two curved tendinous lines
corresponding to the outer border of the recti muscles, extend
on either side from the eighth costal cartilage to the pubes ;
action, flexes the thorax on the pelvis, and vic^j versa, also com-
presses the abdominal viscera ; nerves are the lower intercostals
and perhaps the ilio-hypogastrie.

Pyramidalis : origin, from front of the pubic crest and anterior
pubic ligament, lying in front of, but in same sheath with the
rectus ; insertion, linea alba midway between the pubes and the
umbilicus ; action, a tensor of the linea alba ; nerves, two lower
intercostals and sometimes the ilio-hypogastric.

Quadratus lumborum'^ (Fig. 89) : origin, ilio-lumbar ligament,
adjacent two inches of the iliac crest, and upper borders of the
transverse processes of the three or four lower lumbar vertebrae ;

MUSCLES OF THE THORAX. 150

insertion, one-half of* the lower border of the last rib, apices of
the transverse processes of the four upper lumbar vertebrae ;
action, flexes the trunk — both acting : flexes laterally — one
acting; depresses the ribs with fixed pelvis and is then an ex-
piratory muscle, but by fixing the last rib and opposing the
diaphragm it is an assisfrfjit to inf>pir<itioa ; neny^s, anterior
branches of the last thoracic and upper lumbar.

Muscles of the Thorax.

External intercostals ' ^ (Fig. 90) (eleven pairs): origin, each
from the outer lip of the groove on the lower border of each
rib from the tuberosity to the costal cartilage ; iuHcrtion, pass
obliquely downward and forward to the upper border of the
rib below for same distance ; action, raise and evert the ribs in
inspiration ; nerves for each group are the intercostals.

Internal intercostals (eleven pairs) : origin, each from the
inner lip of the groove on the lower border of the rib reaching
from the angle to the sternum ; insertion, passing downward
and backward to the upper border of the rib below ; action,
depress and invert the ribs in expiration ; probably the two
sets of interco.stals act together in inspiration and in expiration,
depending upon a fixed point above or below.

Infracostales or subcostales are placed posteriorly where the
internal intercostals cease; they vary in number, and are most
common between the lower ribs ; origin, from the inner surface
of one rib ; insertion, inner surface of the first, second, or third
rib below, passing obliquely downward and backward ; action,
same as the internal intercostals; nerves, intercostals.

Triangularis sterni : origin, lower part of the side of the ster-
num, inner surface of the ensiform cartilage, and sternal ends
of the co.stal cartilages of the two or three lower true ribs; in-
sertion, by fleshy digitations into the lower border and inner
surfaces of the costal cartilages of the second to the sixth
ribs inclusive; action, draws down the costal cartilages in ex-
piration ; nerves, intercostals.

Levatores costarum : origin ftw(;lve pairs), extremities of
seventh cervical and eleven upper thoracic transverse proces.ses ;
insertion, rough surface between the tuberosity and angle of the
rib b(;low ; action, assist the external intercostals in raising
the ribs in in.spiration ; nerves, intercostals.

160

ESSENTIALS OF HUMAN ANATOMY.

Diapliragm (Fig. 91) : oriyin. arched and convex toward the
chest, from the ensiform cartilage in front, on either side, inner
surfaces of the cartilages and bony portions of the six or seven
lower ribs, behind, from the ligamentum arciiatum externum ^
and internum ", and by its crura *, ^, the left from bodies of the
two upper, the right, from those of the three or four upper
lumbar vertebrae; iuscrfion, into the central cordiform ten-
don \ '", '^ ; action, chief respiratory muscle, increasing capacity
of the chest by becoming flattened when contracted ; also aids
all eff"orts of expulsion ; nerves, two phrenics and phrenic
plexuses of the sympathetic.

Fig. 91.— The diaphragm, inferior surface (Leidy).

Openings of the diaphragm: the aortic^, median, in front of
the vertebral bodies — really behind the diaphragm — for the
aorta, vena azygos major, thoracic duct, sometimes the left
sympathetic nerve ; the esophageal^, elliptical, muscular,
formed by the crura, for the esophagus and pneumogastric
nerves; the opening for the vena cava^*^, highest, quadrilateral
bounded by four tendinous bundles meeting at right angles ;
the right eriis^ transmits the sympathetic, greater and lesser
splanchnic nerves ; the fe/f cms * the left greater and lesser
splanchnic nerves and the vena azygos minor.

MUSCLES OF THE SHOULDER AND ARM. 161

Muscles of the Shoulder and Arm.

Pectoralis major ^ (Fig. 90): origin, anterior surface of the
inner half of the clavicle, half the breadth of the anterior sur-
face of the sternum as low as the sixth or seventh cartilage, from
the front of the second to the sixth cartilage, from the sixth
rib, and from the aponeurosis of the external oblique ; in-
sertion, fibers converge and overlap, the lower being folded
back upon themselves, to be attached by a flat tendon to the
anterior lip of the bicipital groove of the humerus ; action,
draws the arm forward and inward ; with fixed arm, an acces-
sory muscle of forced inspiration ; nerves, two anterior thoracics.

Pectoralis minor ^ (Fig. 90) : origin, tendinous from the upper
margin and the outer surface of the third, fourth, and fifth ribs
near the cartilages, often from the second, and aponeurosis over
the intercostal muscles ; insertion, inner border and upper sur-
face of the coracoid process of the scapula ; action, depresses the
point of the shoulder, elevates the ribs during inspiration when
the scapula is fixed ; nerve, internal anterior thoracic.

Subclavius ^ : origin, tendinous from the first costal cartilage
and rib ; insertion, groove on the middle third of the under sur-
face of the clavicle ; action, draws the clavicle down and in,
steadies the sterno-clavicular articulation ; nerve, branch from
the trunk formed by the fifth and sixth cervical.

Serratus magnus * (Fig. 90) : origin, by nine fleshy digitations
from the outer surface and upper border of the eight upper
ribs (second rib has two) and aponeurosis covering the upper
intercostal spaces ; insertion, whole length of the anterior
aspect of the posterior border of the scapula ; action, carries the
scapula forward and is used in pushing, also raises the point of
the shoulder by rotating the bone on the chest-wall ; nerve,
posterior thoracic.

Deltoid - (Fig. 90) : origin, outer third of the anterior border
and upper surface of the clavicle, outer margin and upper sur-
face of the acromion process, and the whole length of the lower
border of the spine of the scapula ; insertion, tendinous into
the rough prominence on the middle of the outer side of the
shaft of the humerus ; action, raises the arm to a right angle,
also draws it forward by the anterior fibers, or slightly back-
ward by the posterior portion; nerve, circumflex.

Subscapularis * (Fig. 92) : origin, inner two-thirds of the sub-
U

162

ESSENTIALS OF HUMAN ANATOMY.

scapular fossa; msertt'on, lesser tuberosity and neck of the
humerus; action, rotates the humerus inward and adducts ;
)ierves, upper and lower subscapular.

Supraspinatus ^' (Fig. 88): origin, internal two-thirds of the
supraspinous fossa and the fascia covering it ; insertion^ highest
facet on the greater tuberosity of the humerus ; action, assists
the deltoid, fixes the head of the humerus in its socket ; nerve,
suprascapular.

Infraspinatus ** (Fig. 88) : origin, internal two-thirds of the
infraspinous fossa ; insertion, tendinous, middle facet of the
greater tuberosity of the humerus ; action, rotates the humerus
outward, acts with neighboring tendons as a ligament of the
shoulder-joint ; nerve, suprascapular.

Teres minor ^^ (Fig. 88) : origin, upper two-thirds of the dor-
sal surface near the axillary border of
the scapula and intermuscular septa ; in-
sertion, lowest facet on the greater tuber-
osity of the humerus and a small surface
of the shaft below ; action, rotates the
humerus outward ; nerve, circumflex.

Teres major"-*' (Fig. 88): origin, lower
third of the external border of the infra-
spinous fossa and intermuscular septa
between it and the teres minor and in-
fraspinatus ; insertion, internal lip of the
bicipital groove ; action, draws the hu-
merus downward and backward when
raised, also rotates it inward ; nerve,
lower subscapular.

Coraco-bracliialis ^ (Fig. 92) : origin,
fleshy from the apex of the coracoid proc-
ess of the scapula ; insertion, into the
rough ridge at the middle of the inner
border and surface of the humerus ; ac-
tion, draws the humerus forward and
inward, also elevates it ; nerve, special
branch from the outer cord of the brachial
plexus from the seventh cervical.

Biceps flexor cubiti ^ (Fig- 92): origin,
short head, tendinous, in common with the coraco-brachialis
from the tip of the coracoid process of the scapula, long head,

Fig. 92.— Anterior hum-
eral region (Leidy).

MUSCLES OF THE FOREARM. 163

upper margin of the glenoid cavity by a rounded tendon
continuous with the glenoid ligament ; insertion^ tendinous into
the back part of the tuberosity of the radius (a bursa is inter-
posed in front), and by a broad aponeurosis opposite the elbow,
into the fascia of the forearm ; action^ supinates and flexes the
forearm, renders the forearm fascia tense ; nerve, musculo-cuta-
neous.

BracMalis anticus " : origin, lower half of the outer and inner
surfaces of the shaft of the humerus, embracing the insertion
of the deltoid ; insertion, tendinous into the inferior surface of
the coronoid process of the ulna; action, flexes the forearm;
nerves, musculo-cutaneous and musculo-spiral.

Triceps extensor cubiti ^^ : origin, scapular or Jong head from
the rough triangular depression below the glenoid fossa, the
external head from the posterior surface of the shaft between
the upper part of the spiral groove and the insertion of the
teres minor, the internal head from the posterior surface below
the spiral groove ; insertion, tendinous, back part of the upper ■
surface of the olecranon process of the ulna ; action, extends
the forearm and arm ; nerve, musculo-spiral.

Subanconeus : origin, humerus above the olecranon fossa ; in-
sertion, posterior ligament of the elbow ; action, prevents the
loose capsule from being pinched during extension ; nerve,
musculo-spiral.

Muscles of the Forearm.

Anterior, or flexor and pronator group : All take origin from
the internal epicondyle, except the deep layer.

Superficial layer.

Pronator teres ^ (Fig. 93) : origin, double, above from the in-
ternal supracondylar ridge and common tendon, fascia of the
forearm and intermuscular septum, below from the inner side of
the coronoid process of the ulna ; insertion, tendinous into the
oblique line and rough ridge on the middle of the outer surface
of the shaft of the radius ; action, pronates the forearm and
aids flexion ; nerve, median.

Flexor carpi radialis ^ : origin, internal epicondyle by the
common tendon, forearm fascia, and intermuscular septa; in-
sertion, tendinous, into the base of the index metacarpal bone
and usually of the third ; action, flexes the wrist, then the
forearm ; also pronates the forearm ; nerve, median.

164

ESSENTIALS OF HUMAN ANATOMY.

Palmaris longus^: origin^ inner epicondyle by the common
tendon, fascia, and intermuscular septa; insertion^ tendinous
into the anterior annuhir ligament and palmar fascia, espe-
cially that over the thenar eminence ; action^ tightens the
palmar fascia, flexes the wrist ; nerve, median.

Flexor carpi ulnaris "^ : origin, double, by the common tendon
from the inner epicondyle and from the
inner margin of the olecranon by an apo-
neurosis, and from the upper two-thirds
of the posterior border of the ulna and
intermuscular septum ; insertion, tendi-
nous into the pisiform bone, annular liga-
ment, unciform, and base of the fifth meta-
carpal by means of ligaments ; action,
flexes the hand on the forearm and ad-
ducts ; then flexes the forearm on the
arm ; nerve, ulnar.

Flexor sublimis digitorum ' (perforatus) :
origin, by three heads, one from the inner
epicondyle by the common tendon and
from the internal lateral ligament and
the intermuscular septa, a second from
the inner side of the coronoid process
of the ulna, the third from the oblique
line of the radius ; insertion, by four
tendons, each of which splits for the pas-
sage of the deep flexor tendon, each half
becoming attached to the middle of the
lateral margins of the second phalanges ;
action, flexes the fingers, then the hand
on the forearm, then the forearm on the
arm ; nerve, median.

Fig. 93.— Muscles of the
anterior region of the
right forearm and hand
(Leidy).

Deep layer.

Flexor profundus digitorum (perforans) :

origin, upper three-fourths of the anterior
and internal surfaces of the ulna, inner side of the coronoid proc-
ess, by an aponeurosis from the upper three-fourths of the pos-
terior border of the ulna and ulnar half of the interosseous
membrane ; insertion, into bases of the last phalanges by four
tendons, which pass between the two slips of the flexor sub-

MUSCLES OF THE FOREARM.

165

limis tendons ; action^ flexes the fingers, then the wrist on the
forearm ; nerves, ulnar and anterior interosseous of the median.

Flexor longus pollicis : origin, anterior surface of the radius
from the oblique line to the pronator quadratus, adjacent inter-
osseous membrane, usually a second head
from the base of the coronoid process or
in common with the flexor sublimis from
the inner epicondyle ; insertion, base of
the lapt phalanx of the thumb ; action,
flexes the last thumb-phalanx and wrist ;
nerve, anterior interosseous of the median.

Pronator quadratus : origin, oblique line
on the lower fourth of the anterior sur-
face of the ulna, the bone below this line,
the anterior border of the ulna and apo-
neurosis over the muscle ; insertion, lower
fourth of the anterior surface and exter-
nal border of the radius ; action, pronates
the radius upon the ulna ; nerve^ anterior
interosseous of the median.

Radial region:

Nearly all the extensors and supinators
arise from the external epicondyle and
supracondylar ridge of the humerus.

Supinator longus (brachio-radialis)'

: om-

gin, upper two-thirds of the external su-
pracondylar ridge and anterior surface of
the external intermuscular septum ; in-
sertion, base of the styloid process of the
radius ; action, supinates forearm after it
has been pronated, pronates after supina-
tion, flexes the forearm on the arm ; nerve,
musculo-spiral.

Extensor carpi radialis longior^ (^^ig-
94) : origin, lower third of the external supracondylar ridge
and anterior surface of the external intermuscular septum ;
ivsrrfion, radial side of the })ase of the metacarpal bone of the
index fini^er ; action, extends and abducts the wrist and flexes
the elbow ; nerve, musculo-spiral.

Extensor carpi radialis brevior " : origin, external condyle by

Fig. 91.— Muscles ofthe
j)()steri<)r region of the
right forearm and hand
(Leidy).

166 ESSENTIALS OF HUMAN ANATOMY.

the common tendon, external lateral ligament, the covering
aponeurosis, and the intermuscular septa ; insertion, contiguous
sides of the bases of the second and third metacarpal bones ;
action, extends the wrist and weakly extends the elbow ; nerve,
posterior interosseous.

Posterior radio-ulnar region ; superficial layer :

Extensor communis digitorum*: origin, external epicondyle by
the common tendon, deep fascia, and intermuscular septa ; insei^-
tion, tendon expands over the first phalanx, divides into three
parts: the middle part goes to the second phalanx, the two
lateral unite on the last ; action, extends the fingers, wrist, and
elbow-joint ; nerve, posterior interosseous.

Extensor minimi digiti^: origin, intermuscular septa, rarely
reaches the common tendon ; insertion, by two tendons which
join the common extensor into the phalanges of the little
finger ; action, extends the little finger ; nerve, posterior inter-
osseous.

Extensor carpi ulnaris ^° : origin, by the common tendon from
the external epicondyle, from the deep fascia, intermuscular
septa, with a second head from the posterior border of the
ulna ; insertion, ulnar side of the base of the fifth metacarpal ;
action, extends and adducts the wrist ; extends the elbow ;
nerve, posterior interosseous.

Anconeus : origin, back of the outer condyle of the humerus ;
insertion, side of the olecranon and upper fourth of the poste-
rior surface of the shaft of the ulna above the oblique line ;
action, extends the forearm ; nerve, musculo-spiral.

Deep layer:

Supinator brevis^': origin, external condyle of the humerus,
external lateral ligament and orbicular ligament of the radius,
supinator ridge of the ulna, triangular depression in front of it
and aponeurosis covering the muscle ; insertion, encircling the
neck of the radius posteriorly, it is attached to the upper third
of the shaft, the bicipital tuberosity, and the oblique line;
action, supinates and extends the forearm ; nerve, posterior
interosseous, which pierces it.

Extensor ossis metacarpi poUicis^' : origin, posterior surface of
the shaft of the ulna below the anconeus, interosseous membrane,
and middle third of the posterior surface of the shaft of the

FASCIA OF THE HAND. 167

radius ; insertion, radial side of the base of the first metacarpal,
often a second slip to the trapezium or to the abductor poUicis ;
action, extends the first metacarpal; )ierve, posterior interosseous.

Extensor brevis poUicis^^ : origin, posterior surface of the shaft
of the radius and interosseous membrane ; insertion, base of the
first phalanx of the thumb ; action, extends the phalanx on the
metacarpal, abducts the wrist ; nerve, posterior interosseous.

Extensor longus poUicis^* : origin, posterior surface of the shaft
of the ulna and interosseous membrane below the extensor ossis
metacarpi ; insertion, last phalanx of the thumb ; action, extends
the thumb, abducts the wrist ; nerve, posterior interosseous.

Extensor indicis : origin, posterior surface of the shaft of the
ulna below the extensor longus ; insertion, with the tendon of the
common extensor into the phalanges of the index finger on the
ulnar side; action, extends the index finger and wrist; nerve^
posterior interosseous.

Fasciae of the Hand.

The anterior annular ligament is stretched between the emi-
nentia carpi, which are the pisiform bone and the unciform
process on one side, and the tuberosity of the scaphoid and the
ridge of the trapezium on the other ; it is continuous with the
deep fascia of the forearm and the palmaris longus tendon, and
is pierced by that of the flexor carpi radialis ; beneath it pass
the median nerve and, in one synovial sheath, the tendons of
the flexor sublimis and profundus digitorum, and in a single
sheath the tendon of the flexor longus pollicis.

The posterior annular ligament, continuous with the forearm
fascia, is attached internally on the dorsum to the ulna, cunei-
form, and pisiform bones and palmar fascia externally, to the
ridges on the back of and margin of the radius. Six separate
synovial compartments exist for the extensor tendons ; from
without inward they are: (1) outer side of the styloid process,
for the extensor ossis metacarpi and extensor brevis pollicis ;
(2) behind same process, for the extensor carpi radialis longior
and brevior ; (3) next for the extensor longus pollicis ; (4) more
internally still, for the extensor communis digitorum and ex-
tensor indicis ; (J)) opposite the interval between the radius and
ulna, for the extcn.sor minimi digiti ; and (6) back of the ulna,
for the extensor carjM ulnaris.

TIh' palmar fascia^ ('''c?- •^'^)i <'onsisting of a central and two

168 ESSENTIALS OF HUMAN ANATOMY.

lateral portions, invests the muscles of the hand, forming their
common sheath ; the central segment is triangular, attached to
the })alniaris longus and anterior annular ligament above, below
dividing into four slips opposite the metacarpal heads, each slip
dividing again to enclose the flexor tendons and be inserted on
the sides of the first phalanges ; strong transverse fibers con-
nect the separate processes, and vertical septa, continuous on
each side with the interosseous aponeurosis, separate the middle
from the lateral palmar groups of muscles ; beneath is the su-
perficial palmar arch, median and ulnar nerves ; the lateral por-
tions of this fascia thinly invest the muscles of the thenar and
hypothenar eminences.

Muscles of the Hand.

Abductor poUicis'^ (l^ig- 93): origin, ridge of the trapezium
and annular ligament ; iiii^ertion^ tendinous into the radial side
of the base of the first thumb-phalanx ; action^ draws the thumb
from the median line — i. e. abducts it ; nerve, median.

Opponens pollicis : origin, palmar surface of the trapezium
and annular ligament ; insertion, whole length of the radial
side of the thumb-metacarpal ; action, flexes the metacarpal ;
nerve, median.

Flexor brevis pollicis''' (Fig. 93): origin, by two heads, the
external from the trapezium and outer two-thirds of the an-
nular ligament ; the internal rises from the inner side of the
base of the first metacarpal between the abductor indicis and
adductor obliquus pollicis ; insertion, sides of the base of the
first thumb-phalanx by two tendons, each containing a sesa-
moid bone ; action, as name implies ; nerves, median and ulnar.

Adductor obliquus pollicis rises from the os magnum, bases of
the second and third metacarpals, and tendon-sheath of the
flexor carpi radialis ; insertion, ulnar side of the base of the first
thumb-phalanx and internal sesamoid bone, and sends a fas-
ciculus under the flexor longus tendon to the outer side of the
base of the first phalanx ; action, draws the thumb inward to-
ward the median line ; nerve, ulnar.

Adductor transversus pollicis: origin, lower two-thirds of the
third metacarpal ; insertion, ulnar side of the base of the first
phalanx of the thumb ; action, flexes the phalanx, adducts the
thumb; nerve, \\\\\i\r.

The preceding muscles form the thenar eminence.

MtJSCLES O^ THE LOWER EXTREMITY. 169

Palmaris brevis "^ : origin, tendinous from the annular liga-
ment and palmar fascia ; insertion^ skin on the inner border of
the palm ; action, wrinkles the skin on the inner palmar side ;
nerve, ulnar.

Abductor minimi digiti: origin, pisiform bone and expansion
of the tendon of the flexor carpi ulnaris ; insertion, ulnar side
of the base of the first phalanx of the little finger; action,
draws the little finger from the median line and flexes the
metacarpo-phalangeal joint ; nerve, ulnar.

Flexor brevis minimi digiti: origin, tip of the unciform process
and from the annular ligament; insertion, base of the first pha-
lanx of the little finger with the abductor; action, flexes the
first phalanx ; nerve, ulnar.

Opponens minimi digiti : origin, beneath the preceding, from the
unciform process and annular ligament ; insertion, whole length
of the fifth metacarpal ; action, flexes the fifth metacarpal, and
draws forward to deepen the hollow of the palm ; nerve, ulnar.

The four preceding muscles form the liypotlienar eminence.

Lumbricales: origin, tendons of the deep flexor; insertion, on
radial side into the expansion of the extensor communis tendon
over the dorsum of each finger; they are four in number; action,
flex the first and extend the last two phalanges ; nerves, two
outer by the median, two inner by the ulnar.

Dorsal interossei (four in number) : origin, by two heads from
adjacent sides of the metacarpal bones ; insertion, into bases of
the first phalanges and aponeurosis of the common extensor ;
action, flex the first and extend the last two phalanges, ab-
duct the fingers from a line passing through the center of the
middle finger ; nerve, ulnar.

Palmar interossei (three in number) : origin, by single heads,
from the palmar surface of the second, fourth, and fifth meta-
carpals; insertion, into three fingers as above; action, flex the
first, extend the last two phalanges, and adduct the fingers
toward the middle finger; nerve, ulnar.

Muscles of the Lower Extremity.

Psoas magnus" (Fig. i>5) : origin, margins of the bodies, in-
tervertebral siibstances and bases of the transver.sc processes
of the last thoracic and all the lumbar vertebrae ; insertion, ten-
dinous, with the iliacus, into the lesser trochanter ; action, flexes

170 ESSENTIALS OF HUMAN ANATOMY.

the thigh on the pelvis, or vice versa ; also rotates the femur
outward ; nerves, anterior branches of the second and third
lumbar.

Psoas parvus (often absent) : origin, margins of the bodies
and intervertebral substance between the last thoracic and the
first lumbar vertebrae ; insertion, tendinous into the ilio-pecti-
neal eminence and iliac fascia ; action, tensor of the iliac fascia ;
nerve, anterior branch of the first lumbar.

Iliacus^'^: origin, upper half of the iliac fossa and inner mar-
gin of the iliac crest, ilio-lumbar ligament and base of the sa-
crum, anterior superior and inferior iliac spines, the notch be-
tween them ; insertion, with the tendon of the psoas magnus
into the lesser trochanter; actio)i, same as the psoas magnus;
nerve, anterior crural.

The fascia lata, or deep fascia, is attached above to Poupart's
ligament and the iliac crest, behind to the margins of the sacrum
and coccyx, internally to the pubic arch and linea ilio-pectinea,
and below to the condyles of the femur, tuberosities of the
tibia, and head of the fibula ; three intermuscular septa pass
from its inner surface to the whole length of the linea aspera ;
numerous smaller septa provide separate sheaths for each mus-
cle ; just below Poupart's ligament, at the upper inner aspect
of the thigh, is the large oval sajyhenous opening, formed by the
margins of the pubic and iliac portions of the fascia lata ; Pou-
part's ligament is an artificial production, being in reality the
thickened lower portion of the external oblique aponeurosis
where the fascia lata becomes continuous with it.

Tensor fasciae femoris*: origin, anterior part of the outer lip
of the iliac crest and anterior superior iliac spine ; insertion,
fascia lata one-fourth down the thigh, whence the fascia is con-
tinued down to the tibial head as the ilio-tihial hand ; action,
tensor of the fascia lata and internal rotator of the thigh ; nerve,
superior gluteal.

Sartorius^: origin, anterior superior iliac spine and upper
half of the notch below it ; insertion, aponeurotic into the
upper inner surface of the shaft of the tibia ; action, flexes the
leg upon the thigh, the thigh upon the pelvis, and rotates out,
at the same time drawing the limb inward, thus crossing one
leg over the other ; nerve, anterior crural.

Rectus femoris^: origin, by two tendons, the straight from the
anterior inferior iliac spine, the rejiected from the groove above

MUSCLES OF THE THIGH.

171

the acetabulum ; insertion^ patella in common with the three
next muscles ; action., extends the leg and flexes the hip-joint ;
nerve., anterior crural.

Vastus externus ' : origin., tubercle of the femur, great tro-
chanter, rough line leading thence to the linea aspera, upper

Fig. 9". — >ruscles of the iliac and Fir,. %— Muscles of tlie gluteal

anterior femoral regions. , . , . and posterior femoral regions.

half of the outer lip of the linea aspera, and external inter-
muscular septum ; insertion, aponeurotic into the outer bor-
der of the patella ; action, extends the leg ; nerve, anterior
crural.

172 ESSENTIALS OF HUMAN ANATOMY.

Vastus Internus and crureus^: origin^ line leading from the
inner side of the neck of the femur to the linea aspera and its
whole inner lip, lower half of the outer lip, internal inter-
muscular septum, internal, anterior, and external surfaces of
the shaft of the femur between the anterior intertrochanteric
line and the lower fourth of the bone ; insertion, aponeurotic,
into the inner side of the patella, blending with other portions of
the quadriceps tendon ; action, extends the leg ; nerve, anterior
crural. The preceding four muscles are called the quadriceps
femoris^, \ ®, whose tendon contains the patella^, and is inserted
into the tubercle of the tibia by the ligamentum patellae.

Subcrureus : origin, often by two heads from the lower part
of the shaft of the femur ; insertion, upper part of the synovial
pouch of the knee-joint ; action, draws up the synovial sac ;
nerve, anterior crural.

Gracilis ^^i origin, aponeurotic from the inner margin of the
body and descending ramus of the os pubis ; insertion, upper
inner surface of the shaft of the tibia above and behind the
sartorius ; action, flexes the leg, rotates it in, and adducts the
thigh ; nerve, obturator.

Pectineus ^"^ : origin, linea ilio-pectinea, the bone in front of it,
and from fascia covering it ; insert io)i, rough \me passing from
the lesser trochanter to the linea aspera ; action, flexes, adducts,
and rotates the thigh outward ; nerves, anterior crural, obtu-
rator, and accessory obturator in order of frequency.

Adductor longus '^ : origin, body of the os pubis just below
the angle ; insertion, middle third of the linea aspera ; action,
adducts and flexes thethigh and rotates out; nerve, obturator.

Adductor brevis : origin, the body and outer surface of the
descending ramus of the os pubis; insertion, upper part of the
linea aspera ; action, adducts and flexes the thigh ; nerve, ob-
turator.

Adductor magnus^*: origin, descending ramus of the os pubis,
ascending ramus, outer margin and under surface of the tuber-
osity of the ischium ; insertion, rough line running from the
great trochanter to the linea aspera, whole length of the linea
aspera, and by a tendon into the tubercle above the inner con-
dyle of the femur ; between two portions of the muscle is an in-
terval for the passage of the femoral vessels from Hunter's canal
into the popliteal space ; action, adducts and rotates the thigh
outward, the long fibers to the tubercle may rotate in ; nerves,

MUSCLES OF THE THIGH.

173

obturator and great sciatic ; the portion of tlie muscle attached
to the femur presents four apertures for the perforating arteries.

Gluteus maximus '^ (Fig. 96) : origin^ superior gluteal line of
the ilium and portion of the bone and crest just behind it,
posterior surface of the last two pieces of the sacrum, side of the
coccyx, aponeurosis of the erector spinse muscle, and the great
sacro-sciatic ligament ; insertion, the fascia lata and rough line
runnino; from the great trochanter to the linea aspera between
the vastus externus and the adductor magnus ; action, main-
tains the trunk erect upon the thigh, extends, abducts, and
rotates the thigh outward, is a tensor of the fascia lata ; nerve,
inferior gluteal.

Gluteus medius^ (Fig. 96) : origin, outer surface of the ilium be-
tween the superior and the middle gluteal lines, outer lip of the
crest between the lines, and the
gluteal aponeurosis ; insertion,
tendinous into the oblique line
on the great trochanter ; action,
supports the trunk ; the poste-
rior fibers rotate the thigh out-
ward and extend ; the anterior
fibers flex and rotate the thigh
inward ; the middle fibers ab-
duct ; nerve, superior gluteal.

Gluteus minimus ^ (Fig. 97) :
origin, outer surface of the
ilium between the middle and
the inferior gluteal lines and
margin of the sciatic notch ;
insertion, anterior border of the
great trochanter ; action, flexes,
abducts, and rotates the thigh
inward, aids in maintaining the
trunk erect ; nerve, superior
gluteal.

Pyriformis ■* : origin, by three
fleshy digitations from the sa-
crum between the first, second, third, and fourth anterior sacral
foramina, from grooves leading from them, from the ilium below
the posterior inferior spine, and great sacro-sciatic ligament;
insertion, passing out of the pelvis by the great sacro-sciatic

Fig. 97. — Muscles of the hip,
posterior view (Leidy).

174 ESSENTIALS OF HUMAN ANATOMY.

foramen, is attached to the upper border of the great tro-
chanter; action^ an external rotator of the thigh after ex-
tension, and abductor after flexion ; also draws the pelvis for-
ward when tixed below ; nerves, branches of the sacral plexus.

Obturator internus '^ : o/-/^//<, internal surface and tendinous
arch of the obturator membrane, margins of the obturator fora-
men, broad surface of the bone behind foramen ; insertion,
inner surface of the great trochanter after leaving the pelvis by
the lesser sacro-sciatic foramen ; four or five tendinous bands
pass in the substance of the muscle from its origin to its in-
sertion ; action, similar to the pyriformis ; nerve, branch of the
sacral plexus.

Gemellus superior ^^ : origin, spine of the ischium ; insertion,
with the tendon of the obturator internus into the inner surface
of the great trochanter ; action^ rotates the thigh outward ;
nerve, from the branch to the obturator internus.

Gemellus inferior'"^: origin, tuberosity of the ischium; in-
sertion, great trochanter with the obturator internus ; action,
an external rotator of the thigh ; nerve, twig from the branch
to the ([uadratits femoris.

Obturator externus : origin, inner anterior margin of the ob-
turator foramen and inner two-thirds of the outer surface of
the obturator membrane ; insertion, digital fossa of the femur ;
action, an external rotator of the thigh, may flex and adduct;
nerve, deep branch of the obturator.

Quadratus femoris^'': origin, outer border of the tuber ischii ;
insertion, a tubercle at the center of the posterior intertro-
chanteric line ; action, external rotator of the thigh and an
adductor : nerve, branch of the sacral plexus.

Biceps ^"^ *,^ (^ig- ^6); (Fig. 97) : origin, by two heads, the
long ^^ from the lower inner facet on the tuber ischii by the tendon
common to it and the semitendinosus and from the great sacro-
sciatic ligament, the sliort head^ (Fig. 96), from the linea aspera
between the adductor magnus and the vastus externus, and
from the intermuscular septum ; insertion, outer side of the
head of the fibula, the tendon splitting to embrace the long
external lateral ligament of the knee, one band extending to the
outer tuberosit}^ of the tibia ; this muscle forms the outer
hamstring ; action, extends the hip, flexes the leg, after which
it slightly rotates it outward ; nerve, great sciatic.

Semitendinosus^ (Fig. 96),^^ (Fig. 97): origin, by the com-

MUSCLES OF THE LEG. 1V5

mon tendon with the biceps to the length of three inches from
the tuberosity of the ischium and adjacent aponeurosis ; iuHfr-
tion^ upper inner surface of the shaft of the tibia, behind the
sartorius and below the gracilis ; action^ extends the hip, flexes
the leg on the thigh, rotates it in; nerve, great sciatic.

Semimembranosus^ (Fig- 96): origin, tendinous from the
upper outer facet on the tuberosity of the ischium ; insertion,
groove on the inner tuberosity of the tibia, connected with the
popliteal oblique ligament and with the fascia covering the pop-
liteus muscle, a few fibers forming the short internal lateral
ligament of the knee-joint ; action, extends the hip, flexes the
leg on the thigh, rotates it in ; nerve, great sciatic ; the tendons
of the semimembranosus and semitendinosus form the inner
hamstrings.

Muscles of the Leg.

Tibialis anticus^ (Fig. 08) : origin, outer tuberosity and upper
two-thirds of the external surface of the shaft of the tibia, ad-
jacent interosseous membrane, deep surface of the fascia, and
intermuscular septum ; insertion, inner and under surface of
the front part of the internal cuneiform bone, base of the first
metatarsal ; action, flexes the ankle-joint, rotates the foot in-
ward, adducts the forefoot ; nerve, anterior tibial.

Extensor longus ballucis^: origin, middle two-fourths of the
anterior surface of the fibula, and to the same extent from the
interosseous membrane ; insertion, base of the last phalanx of the
great toe, usually with a slip to the base of the first phalanx ;
action, extends the great toe, otherwise same as the tibialis an-
ticus ; nf^rre. anterior tibial.

Extensor longus digitorum*: origin, outer tuberosity of the
tibia, upper two-thirds of the anterior surface of the fibula,
interosseous membrane, deep surface of the fascia, and inter-
muscular septa; insertion, divides into four tendons, which are
attached to the three phalanges of the four lesser toes ; action^
extends the toes, flexes the ankle, everts the foot, abducts the
forefoot ; nerve, anterior tibial.

Peroneus tertius'': origin, lower third of the anterior surface
of the fibula, interosseous membrane, and intermuscular sep-
tum ; insertion, upper part of the bases of the fourth and fifth
metatarsals ; nerve and action on the foot same as those of
the long extensor.

176

ESSENTIALS OF HUMAN ANATOMY.

Gastrocnemius •'' : origin^ by two heads from the upper back
part of the condyles of the femur and supracondyLar ridges ;
insertion^ with the tendons of the soleus and pUmtaris to form
the tendo AchilHs, which is inserted into the middle part of the

Ivi

Fig. 98.— Anterior muscles of the Fig. 99.— Posterior muscles of the

right leg. (Leidy.) left leg, deep layer.

tuberosity of the os calcis ; action., extends the foot and slightly
rotates it in ; nerve., internal popliteal.

Soleus^/: origin, tendinous, from the back of the head and
upper third of the posterior surface of the fibula, from the ob-
lique line of the tibia, and from the middle third of its inner
border ; imertion, tuberosity of the os calcic by the tendo

MUSCLES OF THE LEG. 177

Achillis ; action^ as above ; nerves, internal popliteal and poste-
rior tibial.

Plantaris: origin, lower part of the outer bifurcation of the
linea aspera and posterior ligament of the knee-joint; insertion,
posterior surface of the os calcis with the tendo Achillis, into
the tendo Achillis, or into the plantar fascia ; action, accessory
to the gastrocnemius ; nerve, internal popliteal.

Popliteus*^ (Fig. 99) : origin, within the knee-joint from the
depression on the outer side of the external condyle of the
femur, and from the arcuate ligament or posterior part of the
capsule; insertion, trianguhir surface above the oblique line of
the tibia posteriorly, and tendinous expansion covering the
muscle ; action, flexes the leg upon the thigh, then rotates the
tibia inward, and draws the capsule backward ; nerve, internal
popliteal.

Flexor longus hallucis^ (Fig. 99) : origin, lower two-thirds of
the posterior surface of the fibula, except its lowest inch,
lower part of the interosseous membrane, intermuscular septum,
deep fascia, and fascia covering the tibialis posticus; insertion,
base of the last phalanx of the great toe ; in the foot always
giving a tendon to the flexor longus digitorum ; action, flexes
the great toe, then extends the foot ; nerve, posterior tibial.

Flexor longus digitorum" (Fig. 99): origin, posterior surface
of the tibia below the oblique line internal to the tibialis pos-
ticus, except the lower three inches, deep fascia, also the inter-
muscular septum ; its tendon passes behind the malleolus in the
groove with the tibialis posticus, but in a separate synovial
sheath ; insertion, bases of the phalanges of the lesser toes by
four tendons, each passing through a fissure in the tendon of
the flexor brevis ; action, flexes the phalanges, and then extends
the foot ; nerve, posterior tibial. With this muscle are connected
the lumbriealcs and the accessorius.

Tibialis posticus'' (Fig. 99): origin, hy two pointed processes,
between which pass the anterior tibial vessels, from the whole
of the posterior surface of the interosseous membrane exce|>t the
lowest part, posterior surface of the tibia, external to the flexor
longus, between tli(! o})li(nie line above and the middle of the ex-
ternal bonier Ixilow, and from the whoh; of tlie internal surface
of tli(! fibula; insertion, tuberosities of the navicular and inter-
n;il (Mirieiform, and sends oftsets to the middle and external cunei-
form, cuboid, sustentaculum tali, and bases of the second, third,
12

178 ESSENTIALS OF HUMAN ANATOMY.

and fourth metatarsals ; action^ extends the foot, adducts and
rotates in : iim-c. posterior tibial.

Peroneus longus' (Fig. 98): origin, outer tuberosity of the
tibia, head and upper two-thirds of the outer surface of the
fibula, deep surface of the fascia, and intermuscular septa,
then it grooves the outer malleolus with the peroneus brevis",
then the os calcis and cuboid ; insertion, outer side of the base
of the first metatarsal and internal cuneiform ; action, extends
and everts the foot; neive, musculo-cutaneous.

Peroneus brevis'' (Fig. 98): origin, lower two-thirds of the
outer surface of the shaft of the fibula, intermuscular septa ;
insertion, passes with the preceding muscle behind the external
malleolus in a groove lined with a common synovial sheath, to
be attached to the dorsum of the base of the fifth metatar.sal,
and sends a slip to the long extensor of the little toe ; action
and nerve, same as the peroneus longus.

Fasciae of the Foot.

The anterior annular ligament consists of (1) an upper verti-
cal portion binding down the extensor tendons, attached to the
lower ends of the tibia and fibula, continuous above with the
deep fascia, and containing only one synovial sheath situated
internally for the tendon of the tibialis anticus ; the exten-
sor longus digitorum. peroneus tertius. and extensor longus
hallucis tendons, the anterior tibial vessels and nerve pass be-
neath it without a distinct sheath ; and (2) a horizontal portion
attached externally to the upper surface of the os calcis, and
internally are two diverging arms, one to the inner malleolus
and one to the plantar fascia, containing three sheaths, that in-
ternal for the tendon of the tibialis anticus, the next for the
extensor longus hallucis. and that most external for the ex-
tensor longus digitorum and peroneus tertius.

The internal annular ligament is a strong band extending from
the inner malleolus to the inner margin of the os calcis. convert-
ing the bony grooves on its surface into canals for the flexor
tendons and the tibial vessels and nerves ; it is continuous with
the deep fascia of the leg, plantar fascia, and the origin of the
abductor hallucis muscle. Its three fibro-osseous canals trans-
mit, enumerated obliquely from within outward, the tendons of
the tibialis posticus, flexor longus digitorum. posterior tibial

MUSCLES OF THE FOOT. 179

vessels and nerve — through a broad space beneath the liga-
ment— and the tendon of the flexor lono-us hallucis.

The external annular ligament stretches between the extremity
of the outer malleolus to the outer surface of the os calcis,
forming a common sheath for the peroneal tendons.

The plantar fascia, the densest of all fibrous membranes, con-
sists of a central and two lateral parts; the former, thick and
narrow behind, arising from the inner tubercle of the os calcis,
divides into a process for every toe. each again splitting oppo-
site the metatarso-phalangeal joint into two slips — over which
passes the flexor tendon — to be attached to the sides of the
metatarsal bone and transverse metatarsal ligament ; two chief
and several subordinate intermuscular septa are given off", sepa-
rating the muscular layers ; the outer and inner segments are
thin, the outer has one strong band giving origin in part to the
abductor minimi digiti.

Muscles of the Foot.

Dorsal region.

Extensor brevis digitorum: origin, outer surface of the os cal-
cis. external calcaneo-astragaloid ligament, and annular liga-
ment ; insertion^ by four tendons, the first into the first phalanx
of the great toe, and is named the extensor hrevis halhtcis ; the
other three into the outer sides of the long extensor tendons
of the second, third, and fourth toes; action, accessory to the
extensors on the four inner toes ; nerve, anterior tibial.

Plantar region. First layer.

Abductor hallucis^ (Fig. 100) : origin, inner tubercle of the os
calcis, internal annular ligament, navicular bone, plantar fascia,
and intermuscular septum; insertion, with inner tendon of the
flexor brevis hallucis into the inner side of the base of the first
phalanx of the great toe ; action, abducts the great toe ; nerve,
internal plantar.

Flexor brevis digitorum '^ : origin, tendinous from the inner
tubercle of the os calcis, central part of the plantar fascia
and the intermuscular septa ; insertion, by four tendons to the
four lesser toes, perforated opposite the middle of the first
ph;ihing(!s by the tendons r>f the long flexor; Iteyond the per-
forations the tendons split to be inserted into the sides of the

180

e>sp:ntials of human anatomy.

second phalanges ; action^ flexes the lesser toes ; nerve^ internal

plantar.

Abductor minimi digiti * : origin, outer tubercle of the os cal-

cis, the bone in front of both tubercles, plantar fjiscia, and

intennuscular septum ; insertion, with
the short flexor of the little toe into the
outer side of the base of the first pha-
lanx ; action , abducts the little toe ; nerve,
external plantar.

Second layer.

Flexor accessorius : origin, by two heads,
from the concave surface of the calcis
and inferior calcaneo-navicular ligament,
from the os calcis in front of the outer
tubercle, and from the long plantar liga-
ment ; insertion, outer margin and upper
and under surfaces of the tendon of the
long flexor of the toes; action, modifies
the oblique pull of the long flexor ; nerve,
external plantar.

Lumbricales ^ : origin, tendons of the
long flexor ; insertion, expansion of the
long extensor over the first phalanges ;
action, flex the first phalanx, extend the
last two ; nerves, the innermost lumbri-
calis by the internal, the three outer by
the external plantar nerve.

Third layer.

Flexor brevis hallucis : origin, inner border of the cuboid and
contiguous portion of the external cuneiform, and prolongation
of the tibialis posticus tendon ; insertion, inner and outer side
of the base of the first phalanx of the great toe by two
tendons, each containing a sesamoid bone, the inner tendon
blending with that of the abductor hallucis, the outer with that
of the adductor obliquus and the adductor transversus hallucis :
action, flexes the great toe ; nerve, internal plantar.

Adductor obliquus hallucis: origin, tarsal extremities of the
second, third, and fourth metatarsal bones and sheath of the
tendon of the peroncus longus ; insertion, with outer portion of

Fig. 100— :>ruRcles of
the sole of the foot, first
layer (Leidy).

THE VASCULAR SYSTEM. 181

the short flexor into the outer side of the base of the first
phahinx of the great toe ; action^ adducts the great toe ; nerve,
external plantar.

Adductor transversus hallucis : ryrigin, inferior metatarso-
phalangeal ligament.s of the three outer toes and transverse
metatarsal ligament ; insertion, with the adductor obliquus
hallucis into the outer side of the first phalanx of the great toe ;
action, adducts the great toe; nerve, external plantar.

Flexor brevis minimi digiti : origin, base of the fifth metatar-
sal and sheath of the peroneus longus tendon ; insertion, outer
side of the base of the first phalanx of the little toe. often to
the head of the fifth metatarsal ; action, flexes and abducts
the first phalanx ; nerve, external plantar.

Fourth layer.

Dorsal interossei (four) : origin, each by two heads from the
adjacent sides of the metatarsal bones ; insertion, tendinous into
the bases of the first phalanges and aponeuroses of the common
extensor ; action, flexes the first phalanx, extends the last two,
abducts toes from an imaginary line passing through the center
of the second toe ; nerves, external plantar and anterior tibial.

Plantar interossei (three) : origin, single heads from the base
and inner sides of the shaft of the third, fourth, and fifth
metatarsal bones ; insertion, inner sides of the bases of the
phalanges and extensor aponeuroses of the same toes; action,
flex and extend as above, and adduct the toes toward a line
passing through the middle of the second toe ; nerve, ex-
ternal plantar.

THE VASCULAR SYSTEM.

What is the pericardium?

A closed fibro-serous sac of conical form, its apex surround-
ing the great ves!?els for about two inches above their origin,
its base downward, attached to the central tendon of the dia-
phragm. The outer fibrous coat is continued as tubular pro-
longations, lost upon the external coats of the roots of all the
great vessels except the inferior vena cava, and is finally trace-
able as continuous with the deep layer of tlie cervical fascia ;
the serous coat lines the sac, forming a ])(rrl<'t(il layer, and is
reflected over the heart and great vos.sels, forming a visceral
layer ; its function is the secretion of a thin fluid in sufficient

182 ESSENTIALS OF HUMAN ANATOMY.

amount to moisten the surfaces, thus lessenin<r friction during
the heart s movements.

Describe the heart and its position.

It is a hollow, conical muscle, with four distinct cavities,
situated obliquely between the lungs, the base upward, back-
ward, and to the right, the apex '^ (Fig. 101) downward, for-
ward, and to the left, corresponding to the fifth intercostal
space, three and a half inches from the middle line of the
sternum. The upper limit of the heart is represented by a line
passing from the lower border of the second left costal cartilage
to the upper border of the third on the right side. The anricido-
ventricular groove is shown by a line drawn obliquely from the
sternal end of the third left cartilage to the upper border of
the sternal end of the seventh on the right side. The right
border is represented by a line from the third right to the
seventh right chondro-sternal articulation, arching outward one
and a half inches from the middle line ; the lovser limit, by a
line from the seventh right articulation to the apex in the fifth
space ; the le/t border, from the second left cartilage to the
apex.

The pulmonary valve is covered by the sternal end of the
third left cartilage ; the aortic valve is a little below and inter-
nal to this, behind the sternum, on a level with the third space,
between the mid-sternal and left sternal lines. The auriculo-
ventricular openings are lower than the arterial. The mitral is
at the sternal end of the third left space (behind the sternal
end of the fourth left costal cartilage. Quain). Draw a hori-
zontal line between the two sternal ends of the fifth cartilages ;
where this line intersects the one marking the auriculo-ven-
tricular groove is the spot indicating the tricuspid valve, behind
the sternum.

Give the size and weight of the heart.

In adults it measures five inches long, three and one-half
broad, and two and one-half thick ; weighs in the male ten to
twelve ounces, in proportion to the body 1 to 169 ; in females,
eight to ten ounces, 1 to 149.

What are the four cavities of the heart called?

The right auricle^ and the right ventricle*, the left auricle
and the left ventricle, separated by a longitudinal septum — indi-

THE VASCULAR SYSTEM. 183

cated externally in front and behind by the interventricular
grooft'ii — dividing the heart into lateral halves, the right or
venous heart, the left or arterial heart ; an oblique anricnlo-
veatricidar groove on the exterior corresponds to the division
between the auricles and the ventricles.

Describe the right auricle.

Larger than the left auricle, with a capacity of about two
fluid ounces; its walls are about one line thick; the venous
blood is poured in by the superior ^ and the inferior venae
cavae '^ and the coronary sinus ; note the following points :

The sinus or atrium, the large quadrangular cavity between
the two venae cavae ; the appendix auricidse, a conical pouch
with dentated edge, projecting forward to the left over the root
of the aorta *^ ; openings of the two venae cavae, also that of the
coronary sinus ^", its orifice guarded by a semicircular fold
called the coronary valve — sometimes two unequal segments are
found; the tubercle of Lou-cr'', a small projection on the right
upper wall directing blood from the superior cava toward the
auriculo- ventricular opening, not marked in man ; the foramina
Thehesii, the mouths of numerous minute veins returning
blood from the heart-muscle ; openings of a few anterior cardiac
veins; the semilunar Eustachian valve ^' hety^e^n the anterior
margin of the inferior vena cava and auriculo-ventricular open-
ing— it is larger in the fetus, serving to direct the blood of the
inferior cava through the foramen ovale; the fossa ovalis^\ an
oval depression at the lower part of the auricular septum, the
site of the oval foramen in the fetus ; the aniiulus oralis, the
prominent margin of the fossa ovalis ; the musculi pectinati,
small prominent muscular columns running across the inner
surface of the appendix and adjoining wall r^f the sinus ; the
oval auriculo-ventrlcidar orifice, about one inch in diameter,
communicating with the right ventricle, its margins formed by
a fibrous ring covered by the lining membrane, and guarded by
the tricuspid valve.

Describe the right ventricle.

Tt is triangular, with the apex downward, not quite reaching
that of the heart, forming with the right auricle the anterior,
rather than the right side of the heart ; its capacity is about

184 ESSENTIALS OF HUMAN ANATOMY.

three fluid ounces ; it presents the following points for ex-
amination :

Above is the conical prolongation called the conits (irten'osus,
from which opens the piiInioiK(ri/ artenj placed to the left of
the auriculo-ventricular orifice, which is surrounded by a fibrous
ring; the pulmonary semihoiar vfdces guard the pulmonary
orifice; the fricusjnd valve^, ^', ^", formed of three triangular
segments — the largest on the left side — by a reduplication
of the lining membrane with interposed fibrous tissue ; the
flaps are called the left, ric/ht, and posterior or septal ; they
are prevented from being forced into the auricle by the

Chordde, tendiaese^", fine tendinous cords stretching from (1)
the columnge carnese to the attached margins of the leaflets,

(2) to their centers, and (3) to their free margins.

The cohminse carnese'^', three varieties of muscular columns,
(1 ) simple ridges, (2) bands attached by both extremities, and

(3) two muscnU j^^^pdlares, muscular eminences from which
arise the chordae tendineae. The anterior muscle is larger and
more constant than the posterior, which may be represented by
two or three smaller muscles.

The three pulmonari/ semilunar valves*^ two anterior, a right
and a left, and one posterior, formed by a reduplication of the
lining membrane with interposed fibrous tissue, with their free
margins strengthened by a bundle of fibrous tissue, whose fibers
radiate from a fibro-cartilaginous nodule — corpus Arantii — to
all parts, except to two narrow lunated portions ( lunulde) on
either side of the nodule, which are forced into contact when
the valves are closed ; above and behind each valve is a dilata-
tion, the sinus of Valsalva.

Describe the left auricle.

Resembles the right in having a principal cavity or sinus
and an appendix, but its walls are thicker, measuring about
one and one-half lines. The following points should be studied :

The openings of the pulmonary veins, usually four in number,
two emptying into the right and two into the left side ; fre-
quently the latter terminate by a common opening.

The oval auriculo-ventricular opening, surrounded by a fibrous
ring, smaller than the right ; the mnsculi pectinati fewer and
smaller than on the right side ; a depression over the site of
the fossa ovalis of the right auricle.

THE VASCULAR SYSTEM.

185

Describe the left ventricle.

Larger and more conical than the right, it forms but little
of the anterior surface, most of the inferior surface and all the
apex" of the heart, its walls being three times as thick as
those of the right ventricle ; its inner surface presents, for
examination :

The circular aortic opening^ with the usual fibrous ring, in
front and to the right of the auriculo-ventricular opening, be-
tween tliem intervenes one of the segments of the mitral valve,
its mouth being guarded by three semilunar valves ; the mitral
valve, composed of two irregular segments — the larger in front

Tig. 101.— The heart, with right auricle and right ventricle laid open (Leidy).

— similar to those of the tricuspid valve, but larger and thicker,
the leaflets being provided with chordjie tendine^ie, whose mode
of attachment is identical with those of the right side. The
firmiliinar aortic valves resemble those of the pulmonary artery,
but are larger and stronger ; two are anterior and one poste-

186 ESSENTIALS OF HUMAN ANATOMY.

rior in the fetal condition. l)ut in the adult one is anterior and
two are posterior, right and left ; the stiluses of V(ihah:a are like
those of the pulmonary artery, and are found behind the aortic
valves.

The columnse earnest are more numerous, but smaller than on
the right side, while there are only two musculi papillares.

What is the endocardium?

The delicate lining membrane of the heart continuous with
the intima of the great vessels, by its reduplications forming
the various valves.

Describe the he art- structure.

It consists of striated anastomosing muscular fibers taking
origin from the fibrous rings surrounding the aortic, pulmo-
nary, and auriculo-ventricular openings, disposed in the auricles
in a deep layer composed of looped and annular fibers, and a
superficial transverse layer ; in the ventricles numerous layers
have been described, the deepest of which run circularly, the
more superficial spirally, curving round the apex to form the
whorl or vortex, those fibers from in front curving around to
enter posteriorly, and vice versa ; the most superficial fibers,
especially those behind, pass across the septum from one ven-
tricle to the other.

The Arteries.

What are the arteries?

(Cylindrical, tubular vessels conveying blood from both ven-
tricles to all parts of the body ; the blood they carry is called
arterial, except in the case of the pulmonary artery conveying
venous blood to the lungs, and the four pulmonary veins re-
turning arterial blood to the left auricle, constituting the lesser
or pulmonic circulation, while the aorta arising from the left ven-
tricle carrying blood to the body generally, and the veins return-
ing it, finally emptying by the two venae cavae into the right
auricle, form the greater or systemic circulation. In their dis-
tribution the arteries freely communicate with one another,
the large branches as well as the small forming what are called
collateral anastomoses or inosculations, permitting the establish-
ment of a collateral circulation after obliteration of a main
artery.

THE ARTERIES.

187

Describe the structure of the arteries.

They possess tliree coats: (Ij an interiutl (serous) or intima ;
(2) a middle (^iiiedi(f), composed in small vessels almost purely
of circular muscular fibers, in the
larger chiefly of yellow elastic tissue ;
this prevents the arteries from col-
lapsing when cut across ; (3) an ex-
teriud (^adventitial, composed of con-
nective tissue. Every vessel, except
the intracranial vessels, is included
with its vein or veins in a fibro-areolar
sheath.

How are the arteries nourished and
their caliber regulated?

The larger vessels are supplied by
minute vasa vasormn, blood-vessels
distributed in a fine network to their
external coats ; while intricate nerve-
networks (plexuses), chiefly derived
from the sympathetic, partly from the
spinal system, supply the two outer
coats of the large vessels — the smaller
are usually supplied only with single
filaments.

What are capillaries?

The intermediate vessels between
the arteries and veins, disposed in the
form of a network, of an average di-
ameter of one-three-thousandths of an
inch, formed of a fine transparent layer
of endothelial cells united by a ce-
ment-substance.

Describe the pulmonary artery.

It is a wide vessel conveying ven-
ous 1)100(1 from the; right ventric](; to
the lungs, about two irich(;s long, and
springs, in front of the aort;i. from the; l(;f"t side of the base of
the right V('ntri(;l(!, lying within tin; pericardium, passing ob-
liquely U) the left, upward and backward, dividing at the under

Fin. 10'_'. - The aorta' and
tliuir branches (Leidy).

188 ESSENTIALS OF HUMAN ANATOMY.

surface of the aortic arcli into a riijlif and a left pulmonary
artery^ the former the longer; each vessel pierces the pericar-
dium and passes horizontally outward to its respective lung,
where it divides into two main branches, one of those of the
right subdividing to supply the third lobe ; these vessels sub-
divide to terminate in the pulmonary capillaries.

Describe the aorta', \^ (Fig. 102).

This, the main trunk of the systemic arteries, arises from the
upper part of the left ventricle, ascends and then arches back-
ward to the left over the root of the left lung to descend within
the thorax on the left side of the vertebral column, entering
the abdominal cavity by the aortic opening** behind the dia-
phragm, where it terminates opposite the fourth lumbar verte-
bra in the two common iliac arteries ^^; the aorta is divided for
convenience of study into the ascending aorta, arch of the aorta,^
thoracic'^, and abdominal aorta^. The branches of each sub-
division are :

From the ascending aorta < Two coronary,

i Innominate,
From arch of the aorta I Left common carotid,

( Left subclavian.

r Pericardiac, Posterior mediastinal.
From the thoracic aortal Bronchial^, Intercostal",^^,

(^ Esophageal

10

From the abdominal aorta are three groups with three in each :

r Gastric '^,
Celiac axis ^ Hepatic ^^,
Visceral ^ ( Splenic '^.

I Superior mesenteric ^^,

1^ Inferior mesenteric ^'.

( Two renal "^°,
Glandular I Two suprarenal *'',

(^ Two spermatic ''^", or ovarian.

r Ten lumbar '^'\
Parietal I Two inferior phrenic '',

( One middle sacral ^\

THE ARTERIES. 189

Give the relations of the aorta in the thorax.

Ascending aorta : a)d<nior^ pulmonary artery, right auricular
appendix, pericardium ; posftrrlor^ right pulmonary artery,
right bronchus, left auricle, pericardium ; right side, superior
vena cava, right auricle ; left side, pulmonary artery.

Arcli of tJie aorta : anterior, pleura and lungs, remains of
the thymus gland, left pneumogastric nerve, left phrenic nerve,
left superior cardiac nerves, left superior intercostal vein ;
jjosterior, trachea, deep cardiac plexus, esophagus, thoracic
duct, left recurrent nerve ; above, left innominate Tein, innomi-
nate artery, left carotid, left subclavian ; beloic, bifurcation of
the pulmonary artery, ligamentum arteriosum, superficial car-
diac plexus, left recurrent nerve, left bronchus, bronchial
glands.

Thoracic aorta: anterior, left pulmonary artery, left
bronchus, pericardium, esophagus (below) ; jxjsterior, vertebral
column, vena azygos minor ; right side, esophagus, vena azygos
major, thoracic duct, right pleura and lung ; left side, left
pleura and lung, esophagus (below j.

Describe the coronary arteries.

The right arises from the aorta above the free margin of the
anterior semilunar valve, passes in the groove between the
right auricle and ventricle to the posterior interventricular
groove, where, dividing into two branches, one continues
onward anastomosing with the left coronary, the other descends
along the interventricular groove to the apex of the heart,
anastomosing with the descending branch of the left coronary ;
the left coronarij. the larger, arises above the free edge of the
left posterior semilunar valve, passes forward between the pul-
monary artery and the left appendix, thence obliquely to the
anterior interventricular groove, where it divides, one branch
passing around to join the right vessel, the other descending in
the groove to anastomose at the apex with the descending
branch of the right vessel.

Describe the innominate artery *.

Arising from the commencement of the arch of the aorta, it
is from one and a half to two irjches long and bifurcates at the
upper border of the right sterno-clavicular articulation into the
right common carotid'' and subclavian"; sometimes it sends off

190 ESSENTIALS OF HU^FAN ANATOMY.

a tliyroldeu una branch ; occasionally no innominate exists, the
right carotid and subclavian springing directly from the aorta.
Rdations of the innominate artery are : in front, sternum,
sterno-hyoid and sterno-thyroid muscles, remains of the thy-
mus gland, left innominate vein, right inferior thyroid vein,
inferior cervical cardiac branch of the right pneumogastric
nerve ; right side, right innominate vein, right pneumogastric
nerve, pleura; left side, remains of the thymus gland, left
carotid artery, left inferior thyroid vein, trachea; behind,
trachea.

Describe the common carotid^, ^

The right common carotid artery^ arises opposite the right
sterno-clavicular joint from the innominate, the left from the
summit of the aortic arch. In the neck their course corre-
sponds to a line passing from the sterno-clavicular joint to a
point midway between the mastoid process and the angle of
the lower jaw ; below, the trachea only separates them, above
there is a wide interval ; a common sheath of deep fascia en-
closes the internal jugular vein, the pneumogastric nerve
(posterior to both) and artery, enumerated from icithout
inicard, while upon the sheath lies the branch of the first
and second cervical nerves (descendens cervicalis).

The anterior relations of the vessel for the most of its course
are the anterior margin of the sterno-cleido-mastoid muscle, while
about its middle it is crossed by the omo-hyoid muscle, the
anterior jugular and middle th^^roid veins, while above the
omo-hyoid muscle, the stern o-mastoid artery, and the superior
thyroid vein cross it ; at the lower part of the neck the right
internal jugular vein diverges from the artery, but the left
often crosses the lower part of the corresponding artery ; it is
also in relation anteriorly to the sterno-hyoid, sterno-thyroid,
and platysma muscles, to the deep and superficial fasciae and
skin. Internally lie the trachea, the thyroid gland, recurrent
laryngeal nerve, inferior thyroid artery, larynx, and pharynx.
Posteriorly are the longus colli and rectus capitis anticus
major muscles, sympathetic and recurrent laryngeal nerves,
and inferior thyroid artery. Opposite the upper border of the
thyroid cartilage each vessel divides into the internal ?Lnd. the ex-
ternal carotid. The common carotid arteries have no branches.

The left common carotid artery has, in addition to the above

THE ARTERIES. 191

description, a fhoracic portion which presents the following
relations: in front, sterno-hyoid and sterno-thyroid muscles,
left innominate vein, remains of the thymus gland ; behind^
trachea, esophagus, thoracic duct, left subclavian artery, its

Fig. 103.— The arteries of the face and scalp (Leidy).

thoracic portion ; infprnall)/, innominate artery, inferior thyroid
veins, and remains of the thymus gland ; externally, left pneumo-
gastric nerve, left pleura and lung, and left subclavian artery.

Name the branches of the external carotid artery, with their
subdivisions.

1. Superior tlii/roixV (Fig. 103), arising below the greater
cornu of the hyoid^bone; its branches are:

Muscular, Hyoid, Superior laryngeal,

Superficial descending (sterno-mastoid), Crico-thyroid.

2. /y/y/y/zr// ;iris(!s between the superior thyroid and the facial
running })eneath the hyoglossus muscle to the under surface of
the tongue ; its branches are :

Ilyoid, Dorsalis linguic, Sublingual, Ranine.

192 ESSENTIALS OF HUMAN ANATOMY.

3. Facial^ arises just above the lingual to cross the lower jaw
just anterior to the masseter muscle ; its branches are :

Muscular '^
Inferior labial **,
Inferior coronary^,

Muscular,
Inferior or ascend-

Cervical ^ m '^n ' Facial

lonsillar,

Submaxillary,

Submental \

Superior coronary
Lateralis nasi ",

Angular ^'\

4. OccijyitaP^ arises posteriorly opposite the facial, lies in
the occipital groove of the temporal bone ; its branches are :

Muscular, Sterno-mastoid, Mastoid, Auricular,

Princeps cervicis. Meningeal, Terminal or Cranial.

5. Posterior auricular ^^ arises opposite the styloid process,
ascends beneath the parotid gland to the groove between the
cartilage of the ear and the mastoid process ; its branches are :

Muscular, Parotid, Stylo-mastoid,

Auricular, Mastoid or Occipital.

6. Ascending pharyngeal^ running between the carotid and
the side of the pharynx, its branches being very numerous
and inconstant, and divided into three sets — .

Pharyngeal, Meningeal, and Prevertebral.

7. Svperficial femp07'al, terminal branch, commences in the
substance of the parotid gland, crosses the root of the zygoma,
two inches above which it divides into the anterior '^* and ^poste-
rior'^^ femjwral; its other branches are :

Parotid, Articular, Masseteric, Anterior auricular,

Transverse facial ^°, Middle temporal ^^, and Orbital ^'^

8. Internal maxillari/^, the larger terminal branch, passes
inward at right angles to the carotid at fhe inner side of the
neck of the condyle of the lower jaw ; it is divided into three
portions : (1) maxillary^ (2) pterygoid, and (3) spheno-maxil-
lary (Fig. 104) :

(1) Deep auricular. Small meningeal,

Tympanic, ( Mylo-hyoid,

Middle meningeal. Inferior dental X Incisor,

( Mental.

THE ARTERIES.

(2) Deep temporal -I . • ' at

^ -^ r 1 ^ posterior, iMasseteric,

Pterygoid, Buccal.

(3) Alveolar, Vidian.
Infraorbital, Pterygo-palatine,
Superior or Descending Nasal or Spheno-palatine.

palatine.

193

/mJJ/e Menivffeal
^Icwnyca Parva

Ti/m/ianic-
l-nfiritT Denial-

Fig. 104.— Plan of the branches of the internal maxillary artery (Gray).

Relations of the external carotid arte)?/ : antero-external,
skin, superficial and deep fascia, platysma, anterior border of
the sterno-mastoid, hypoglossal nerve, lingual and facial veins,
posterior belly of the digastric and stylo-hyoid muscles, parotid
gland with branches of the facial nerve, temporo-maxillary
vein, lymphatic glands, and internal carotid artery ; posterior,
superior laryngeal nerve, stylo-glossus and stylo-pharyngeus
muscles, glosso pharyngeal nerve, pharyngeal branch of the
pneumogastric, stylo-hyoid ligament and parotid gland ; the
latter six of this group separate the external from the internal
carotid artery ; internal, hyoid bone, pharynx, superior laryn-
geal nerve, parotid gland, ramus of the jaw, stylo-maxillary
ligament.

Describe the internal carotid artery.

It runs in front of the tran.^ verse processes of the three
upper cervical vertebrae in contact with the pharynx and ton-
sil to the carotid canal of the temporal bone, enters the skull,
passes through the cavernous sinus and pierces the dura mater
near the anterior clinoid process, where it divides into the ante-
rior and the middle cerebral arteries.

13

194

ESSENTIALS OF HUMAN ANATOMY.

Name its branches.

Tympanic (deep), from the artery in the carotid canal, anas-
tomosing with the tympanic branch of the internal maxillary,
stylo-mastoid, and Vidian arteries.

Arterise receptacull, small vessels supplying the cavernous
and inferior petrosal sinuses, pituitary body, and Gasserian
ganglion ; some to the dura mater anastomosing with the mid-
dle meningeal are called the anterior meningeal.

Ophthalmic., from the cavernous portion, enters the orbit by
the optic foramen, dividing at the inner angle of the eye into
two terminal divisions, the frontal and the nasal ; its branches
are :

Orbital
group

Lacrimal,

Supraorbital,

Posterior ethmoidal,

Anterior ethmoidal,

Palpebral,

Frontal,

Nasal.

Ocular
group

[ Muscular,

I Anterior ciliary,

I Short ciliary.

Long ciliary,

Arteria centralis re-
tinae.

Anterior cerebral passes forward in the great longitudinal
cerebral fissure, and communicates with its fellow by the ante-,
rior communicating artery, a vessel about two lines long.

Middle cerebral, the largest branch, is lodged in the Sylvian
fissure and divides into the antero-lateral ganglionic branches^
which enter the anterior perforated space ; the external., inferior,
and ascending frontal, and the ascending parietal , supplying the
parts indicated ; the parieto-temporal ^ to the convolutions around
the horizontal limb of the Sylvian fissure.

Anterior choroid^ to the hippocampus major, corpus fim-
briatum, velum interpositum, and choroid plexus.

Posterior commnnicating runs back to anastomose with the
posterior cerebral, a branch of the basilar artery.

Describe the circle of Willis.

It consists of a vascular anastomosis at the base of the brain,
between the branches of the carotids and basilar artery, whereby
pressure on or blocking of any two of the main trunks will
not prevent both sides of the brain from receiving a supply of
blood. Its formation is as follows : the two vertebrals by
their junction form the basilar, which divides into two paste-

THE ARTERIES. 195

rior cerehrals, these latter being connected with the back part
of the internal carotids on each side by a poster if/r commimi-
cating^ while the anterior terminals of the carotids, viz., the
anterior cerebral on each side, are connected in front by the
short anterior communicating artery before mentioned.

Describe the subclavian artery.

On the right side it springs from the innominate, on the left
directly from the aortic arch. It is divided into three portions,
viz., that internal to the anterior scalene muscle, that behind
the muscle, and that external to the scalene, this muscle inter-
vening between the artery and the subclavian vein ; it ceases to
be called subclavian at the lower border of the first rib. then
being termed axillary. The branches arise from the first por-
tion, except the right superior intercostal, which comes from
the second; the posterior scapular or suprascapular often comes
from the third portion.

Relations of the right subclavian artery: first portion; anterior^
skin, superficial and deep fasciae, platysma, clavicular origin of
the sterno-mastoid. the sterno-hyoid, and sterno-thyroid muscles,
beginning of right innominate vein, internal jugular and verte-
bral veins, pneumogastric, cardiac, and phrenic nerves ; poste-
rior, recurrent laryngeal nerve, sympathetic, apex of the lung
and pleura, longus colli, neck of the first rib; inferiorhj are
the pleura and lung.

Second portion ; anterior, skin, two layers of fascia, platysma,
sterno-mastoid, phrenic nerve, scalenus anticus, subclavian vein;
posterior, pleura, lung, and scalenus medius ; above is the
brachial plexus, and below, the pleura and lung.

Third portion ; anterior, skin, two layers of fascia, platysma,
descending branches of the cervical plexus, nerve to the sub-
clavius, subclavius muscle, suprascapular artery and vein,
external jugular and transverse cervical veins, clavicle ; behind
is the scalenus medius ; above is the brachial plexus, omo-hyoid
muscle ; belov) is the posterior groove on the first rib.

Relaiions of the first portion of the left subclavian artery : in
front, left pleura and lung, left carotid artery, left internal
jugular, vertebral, and innominate veins, vagus, phrenic, and
cardiac nerves ; superfici(dly, the sternohyoid, sterno-thyroid,
and sterno-mastoid muscles ; internally, trachea, esophagus, and
thoracic duct ; externally, pleura ; behind, esophagus, thoracic

196 ESSENTIALS OF HUMAN ANATOMY.

duct, inferior cervical ganglion of the sympathetic, and the
longus colli separating .it from the vertebral column.

The hranches are :

Vertfhral. which passes through the foramina in the cervical
transverse processes except that of the seventh, enters the
skull through the foramen magnum, joining its fellow at the
lower border of the pons A^arolii to form the basihr artery ;
its branches are :

( Lateral spinal, ( Anterior spinal,

^ • 1 j Muscular. ^, . ,

Cervical < t> . • • Lranial

I rosterior menin-

Posterior spinal.
Posterior inferior
cerebellar.

I geal.
Basilar, formed by the vertebrals, gives off the following:

Transverse. Superior cerebellar,

Internal auditory. Posterior cerebral.

Anterior, Inferior cerebellar.

Thyroid axis divides almost at once into the

1. Inferior thyroid, to the same named gland, giving off the

Inferior laryngeal, Esophageal,

Tracheal, Muscular. Asc-ending cervical.

2. Svprascapidar. chiefly to the shoulder-joint and supra-
spinous fossa ; it anastomose? with the acromio-thoracic, pos-
terior circumflex, the posterior and subscapular arteries.

3. Transversalis colli, larger than the preceding, passes trans-
versely outward to the trapezius, beneath which it divides into
the

Superficial cervical. Posterior scapular.

Internal mammary arises from the under surface of the first
portion, opposite the thyroid axis, descends behind the costal
cartilages half an inch from the sternum to the sixth interspace,
where it divides into the muscido-phrenic and the superior epi-
gastric., the latter anastomosing with the deep epigastric and
its fellow ; the branches are :

Superior phrenic, or Anterior intercostal.

Comes nervi phrenici, Perforating.

Mediastinal, Lateral infracostal,

Pericardiac, Musculo-phrenic.

Sternal, Superior epigastric.

Superior intercostal passes in front of the neck of the first

The arteries. 197

rib, giving off the deep cervical, and two Intercostals which have
posterior muscular and sjiiiial branches.

Profunda cervicis supplies the posterior cervical muscles and
anastomoses with the deep branch of the princeps cervicis from
the occipital.

Describe the axillary artery.

It extends from the lower border of the first rib to the lower
border of the tendon of the teres major muscle, where it takes
the name of the brachial ; it is divided into three parts by the
crossing made by the pectoralis minor muscle.

Relations of the first portion : anterior^ skin, two layers of
fascia, platysma, pectoralis major, costo-coracoid membrane,
external anterior thoracic nerve, acromio-thoracic and cephalic
veins ; external, brachial plexus ; internal^ axillary vein ; pos-
terior^ fir.st intercostal space, and intercostal muscle, second
and part of third serrations of the serratus magnus, posterior
thoracic, and internal anterior thoracic nerves.

Second portion : in front., integument, fasciae, pectoralis
major and minor ; external^ outer cord of the brachial plexus ;
internal, axillary vein, inner cord of the plexus ; behind, sub-
scapularis, posterior cord.

Third portion : anterior, integument, fasciae, pectoralis
major, inner head of the median nerve, outer brachial vena
comes ; posterior, subscapularis, tendons of the latissimus
dorsi and teres major, musculo-spiral and circumflex nerves;
external, coraco-brachialis, median and musculo-cutaneous
nerves ; internal, ulnar, internal cutaneous, and lesser inter-
nal cutaneous nerves, axillary vein.

The frst portion is 2.5 cm. (1 inch) long, and gives off the
superior thoracic branch ; the second portion is 3 cm. (1-1- inch)
long, and gives off the acromio-thoracic and long thoracic ; the
third portion is 7.5 cm. {?> inches) long, and gives oft" the alar
thoracic, subscapular, posterior circumflex, anterior circumflex,
and often the accessory external mammary.

The branches are :

Superior thoracic, supplying the pectoral muscles and the
thoracic wall.

Acromio-thoracic, supplying the deltoid by acromial branches,
the serratus magnus and pcctorales by the thoracic, the descend-
ing, or humeral, which runs with the cephalic vein between the

198 ESSENTIALS OF HUMAN ANATOMY.

deltoid and the pectoralis major, and the clavicular to the sub-
clavius muscle.

Long thoracic (external mammary), to the chest-muscles and
mammary gland.

Alar thoracic, supplies the axillary glands.

Subscapular, anastomosing with the supra and posterior
scapular arteries, and giving oft' the dorsalis scapulst branch.

Posterior circmn.flf'x, to the deltoid muscle and shoulder-joint ;
it anastomoses with the anterior circumflex, suprascapular,
acromio-thoracic, and superior profunda arteries.

Anterior circumjlex, to the shoulder-joint and deltoid.

Accessory external mammary , often is a branch from the third
portion, runs downward and inward, and supplies the skin and
fascia on the side of the thorax.

Describe the brachial artery.

A continuation of the axillary, extending from the lower
border of the teres major tendon to its bifurcation into the
radial and ulnar, usually opposite the neck of the radius ; the
median nerve crosses it from without inward about midway in
its course.

Its relations are : in front, integument, fasciae, bicipital
fascia, median basilic vein, and median nerve ; externally,
vena comes, median nerve (above), coraco-brachialis, and bi-
ceps ; internally, vena comes, internal cutaneous and ulnar
nerves, median nerve (below), basilic vein; behind, middle and
inner heads of the triceps, musculo-spiral nerve, superior
profunda artery, insertion of the coraco-brachialis, brachi-
alis anticus. Its branches enumerated from above down-
ward are :

Superior profunda, descending with the musculo-spiral nerve,
giving off" a posterior articular branch, which anastomoses with
the interosseous recurrent and anastomotica magna, while the
anterior terminal twigs of the main trunk inosculate with the
radial recurrent.

Medullary artery, to the humerus.

Inferior profunda, anastomosing with the posterior ulnar re-
current and anastomotica magna.

Anastomotica magna, anastomosing with the posterior artic-
ular of the superior profunda, inferior profunda, and posterior
ulnar recurrent.

THE ARTERIES. 199

Muscular, to the arm -muscles ; special ones to the biceps and
deltoid.

Describe the radial artery.

It appears to be a continuation of the brachial, but is much
smaller, extending from the bifurcation at the elbow along the
radial side of the forearm to the wrist, where, winding around
the thumb, it passes between the two heads of the first dorsal
interosseous muscle to the palm, there inosculating with the
deep or communicating branch of the ulnar to form the deep
palmar arch.

Its relations are : in front, skin, fasciae, supinator longus mus-
cle ; internally, pronator teres and flexor carpi radialis ; exter-
nally, supinator longus, radial nerve ; behind, tendon of the
biceps, supinator brevis, flexor sublimis digitorum, pronator
teres, flexor longus pollicis, pronator quadratus, radius.

The branches of the radial are in the

Forearm Wrist

Radial recurrent. Posterior carpal,

Muscular, First dorsal interosseous,

Superficialis volae, Dorsales pollicis,

Anterior carpal. Dorsalis indicis.

Hand
Princeps pollicis,
Radialis indicis.
Three superior perforating,
Three palmar interosseous.
Palmar recurrent.

The last three are branches from the deep palmar arch.

Describe the ulnar artery.

J^arger than the i)receding, it passes from the bifurcation
obliquely inward to the middle of the forearm, thence runs
along its ulnar border, across the annular ligament to the radial
side of the pisiform })one, curving across the palm, where, either
anastomosing with the superficialis volae, princeps pollicis, or
radialis indicis of the radial, it forms the

SuiH'rJicial p<dniar arcli, whose branches are the four digitals.

Relations : in front, fascia), superficial layer of the flexor

200

ESSENTIALS OF HUMAN ANATOiMY.

muscles, median nerve ; internalhj, flexor carpi ulnaris, ulnar
nerve ; exienudhj, flexor sublimis digitorum ; behliul^ brachialis
anticus. flexor profundus digitorum.
The branches of the ulnar are in the

Forearm

Anterior ulnar recurrent,
Posterior ulnar recurrent,

_, . ( Anterior interosseous

Common interosseous

Muscular.

I Posterior interosseous

Median,

Muscular,

Medullary to
the radius,

Medullary to
the ulna,

Anterior com-
municating,

Terminal.

Wrist
Anterior carpal.
Posterior carpal.

Hand
Deep, or communicating branch.
Superficial palmar arch — four digitals.

Describe the thoracic aorta.

Commencing at the left side of the lower border of the
fourth thoracic vertebra, it terminates at the aortic opening, in
the diaphragm in front of the body of the last thoracic ver-
tebra.

RrJdfions : in front ^ left pulmonary artery, left bronchus,
pericardium, esophagus (below) ; right side, esophagus, vena
azygos major, thoracic duct ; left side, left pleura and lung,
esophagus (below) ; hehind, vertebral column, vena azygos
minor.

Its branches are visceral and parietal.

Peric(irdi(d. variable in number and origin, for the pericar-
dium.

BroncJu'rd. variable in number and origin, usually one right
and two left, for the lung-tissue proper.

Esophageal, commonly numbering four to five, anastomosing
around the esophagus with branches of the inferior thyroid,
phrenic, and gastric arteries.

THE ARTERIES. 201

Posterior mediastinal^ numerous and small to the glands,
areolar tissue, and vertebral portion of the diaphragm.

Infercosfais, usually nine on either side, each dividing into
an anterior and a posterior branch, the former subdividing into
two at the angle of the rib, one branch running in the groove
at the lower border of the rib above, the other running along
the upper border of the rib below, in front both anastomosing
with the anterior intercostal branches of the internal mammary,
with the thoracic branches of the axillary, with the epigastric,
phrenic, and lumbar arteries ; the posterior division supplies
the vertebrae, spinal cord, dorsal muscles, and skin.

Subcostal J or the ticdfth thoracic artery^ passes along the
lower border of the twelfth rib.

Describe the abdominal aorta.

It commences at the aortic opening of the diaphragm in
front of the body of the last thoracic vertebra, whence descend-
ing a little to the left of the vertebral column it terminates on
the body of the fourth lumbar vertebra by dividing into the
common iliacs.

Relations : anterior^ lesser omentum and stomach. Spigelian
lobe of the liver, lower end of the esophagus, celiac axis and
branches, inferior mesenteric, spermatic or ovarian arteries^
splenic vein and commencement of the vena portse.^ left renal vein,
aortic and soljtr plexuses, j^ancreas, 2'>'>'^f^^^f't'c diiodemmi, small
intestines, mesentery, transverse mesocolon, lymphatic glands and
vessels ; of the above the parts in it(dics are in contact with the
aorta; posterior, left lumbar veins, left crus of the diaphragm,
beginning of the thoracic duct, vertebral column ; right side,
right crus of the diaphragm, inferior vena cava, vena azygos
major, thoracic duct, right semilunar ganglion, right great
splanchnic nerve, Spig(!lian lobe of the liver ; left side, loft crus
of the diaphragm, left great splanchnic nerve, left semilunar
ganglion, tail of the pancreas.

Its branches are :

Celiac axis, arises opposite the margin of the diaphragm,
passes for half an inch forward to divide into the

(iastrie or coronary, passing upward to the left to the cardia ;
it turns sharply froT)i the left to the right along the; lesser cur-
vature c»f the stomach, anastomosing with the aortic esophageal,
splenic, and hepatic arteries.

202 ESSENTIALS OF HUMAN ANATOMY.

Hepatic, dividing in the transverse fissure into the right
and left terminal branches for the same lobes of the liver ;
its branches are —

Pancreatic,

Pyloric,

/-, , 1 T 1. ( Gastro-epiploica dextra,
(jrastro-duodenalis < ^ .• i i i-

( rancreatico-duodenaiis superior,

Cystic,

whereby it supplies the parts indicated by the names, and
anastomoses with the splenic, gastric, and superior mesenteric
arteries.

Splenic, the largest branch, passes behind the upper border
of the pancreas to the spleen, giving oiF five or six splenic
branches, and the

Pancreaticae parvae, Gastric (vasa brevia),
Pancreatica magna, Gastro-epiploica sinistra.

Inferior phrenic, one on each side (sometimes one from the
celiac axis instead of the aorta, or by a common trunk) to the
under surface of the diaphragm. Each gives off a superior
suprarenal artery.

Superior mesenteric comes off about one-quarter inch below
the celiac axis, arching forward and downward to the left, sup-
plying all of the small intestine, except the first part of the
duodenum, also the cecum, ascending, and transverse colon,
giving off the

Inferior pancreatico-duodenal, Ileo-colic,

Vasa intestini tenuis, Colica dextra,

Colica media.

Inferior mesenteric, arising from the left side of the aorta
two inches above the bifurcation, passes down into the left
iliac fossa and pelvis, supplying the descending colon, sigmoid
flexure, and greater part of the rectum, anastomosing above
with the middle colic of the superior mesenteric, supplying the
transverse colon in part ; its branches are :

Colica sinistra, Sigmoid, Superior hemorrhoidal.

Middle supraroial, each arises opposite the superior mesen-
teric to supply the suprarenal body.

Renal, spring nearly at right angles from the sides of the

THE ARTERIES. 203

aorta below the superior mesenteric, the right longer and lower
than the left ; each divides into four or five branches before
entering the hilum, intervening between the renal vein in front
and the ureter behind and below. It gives off the inferior
suprarenal artery^ making three for that body.

Spermatic (ovarian in the female), spring from the front of
the aorta on each side, a little below the renals, run behind the
peritoneum to pass in the male through the abdominal ring to the
testis, in tha female between the laminae of the broad ligament
to the ovary, Fallopian tube, uterus, and to the round ligament
and inguinal canal.

Lumbar., commonly four on each side corresponding to the
intercostals, and like them dividing into :

Dorsal branches to the vertebrae, spinal cord, and back mus-
cles, and abdominal branches, passing forward to anastomose
with twigs from the epigastric, internal mammary, intercostals,
ilio-lumbar, and circumflex iliac.

Middle sacral.) springs from the bifurcation of the aorta,
descends along the middle of the sacrum and coccyx, sending
branches to the rectum, anastomosing with the hemorrhoidal
and lateral sacral arteries, terminating in the coccygeal gland.

Describe the common iliac arteries.

They extend from the aortic bifurcation at the left of the
umbilicus, corresponding to a line touching the highest points
of the iliac crests, to divide opposite the intervertebral disk
between the last lumbar vertebra and the sacrum, into the in-
ternal and the external iliac ; the right vessel is somewhat the
longer, both being about two inches long, and each at its bifur-
cation is crossed by the ureter.

Relations of the right common iliac: in front ^ peritoneum,
small intestine, sympathetic nerves, ureter; outer side, vena
cava, right common iliac vein, psoas muscle ; behind, two last
lumbar vertebra3, right and left common iliac veins.

Reldfions (f the left common iliac : in front, same as for the
right, with the superior hemorrhoidal artery added ; inner side,
left common iliac vein ; outer side, psoas muscle ; behind, two
last lumbar vertebrae, left common iliac vein.

Describe the internal iliac artery.

It measures about one and a half inches, arising at the point

204 ESSENTIALS OF HUMAN ANATOMY.

of bifurcation of the common iliac, to divide at the upper
mari^in of the great sacro-sciatic foramen into the anterior and
the posterior trun/:. In the adult it is smaller than the exter-
nal, the reverse in the fetus. A partially obliterated cord, the
fetal hypogastric artery^ extends from its bifurcation to the
bladder.

Relations: in front, peritoneum, ureter; outer side, psoas
magnus ; inner side, internal iliac vein, peritoneum; behind,
external iliac vein (above), internal iliac vein, lumbo-sacral
nerve, sacrum.

Branches of the anterior division : Superior vesical, part of
the fetal hypogastric artery- ; it gives off the artery of the vas
deferens and supplies the ureter, as well as the bladder.

Middle vesical, usually a branch of the former to the bladder
and vesiculae seminales.

Inferior vesical (vaginal in the female), arising in common
with the middle hemorrhoidal, is distributed to the base of the
bladder, prostate gland, and seminal vesicles.

Middle hemorrhoidal, supplies the rectum.

Uterine, anastomoses with the ovarian ; gives twigs to the
bladder and ureter.

Ohturator, passes through the obturator canal to the thigh,
there dividing into an internal and an external branch, anasto-
mosing with twigs of the internal circumflex ; inside the pelvis
its branches are :

Iliac, to the same named bone and muscle anastomosing with
the ilio-lumbar ; a vesiad, to the bladder ; and a pubic, inosculat-
ing back of the pubes with the epigastric and its fellow ; in
two out of three cases the obturator springs from the internal
iliac, in one in three and a half cases from the epigastric,
in one in seventy-two cases it has two roots.

Internal pudic. the smaller terminal of the anterior division,
is distributed to the external organs of generation ; giving off
the following branches :

Inferior hemorrhoidal, Muscular,

Superficial perineal. Artery of the bulb,

Transverse perineal. Artery of the corpus cavernosum,

Dorsal artery of the penis.

tSciatic, the larger terminal, supplies the muscles on the back
of the pelvis ; its branches are :

THE ARTERIES. 205

Muscular, Coccygeal, Comes nervi ischiadici,

Inferior gluteal, Anastomotic, Cutaneous,

Articular (hip).

Branches of the posterior division : Ilio-lumhar^ dividing into
an iliac and a lumbar branch supplying the muscular, spinal,
and nutrient branches, anastomosing with the last lumbar,
external circumflex, gluteal, epigastrics, deep circumflex iliac,
and obturator.

Lateral sacral^ superior and inferior on each side emerge
from the posterior sacral foramina, anastomosing with the glu-
teal and sciatic arteries.

Gluteal ends the posterior division, divides into a superficial
and a deep branch, the latter giving off" a superior and an in-
ferior branch.

It has muscular, cutaneous, nutrient (to the ilium), and artic-
idar branches, anastomosing with the circumflex iliac, external
circumflex, and sciatic arteries.

Describe the external iliac artery.

Passes along the inner border of the psoas muscle from the
bifurcation of the common iliac to Pouparts ligament ; a line
drawn from the left side of the umbilicus to the midpoint
between the symphysis pubis and the anterior superior iliac
spine (in female's a little nearer the former), indicates the
course of the common and external iliac.

Rdations : in front, peritoneum, intestines, and fascia,
lymphatic vessels and glands; near Pouparts ligament arc the
spermatic vessels, genital branch of the genito-crural nerve,
deep circumflex iliac vein ; externalli/, psoas magnus, iliac
fascia ; internally, external iliac vein and vas deferens ; behind,
external iliac vein, psoas magnus, iliac fascia.

Its branches are :

Muscular, Lymphatic (to glands).

Deep epigastric. Deep circumflex iliac.

Deep epigastric, usually coming off" just above Poupart's
ligament, passing between the peritoneum and transversalis
fascia, pierces the fascia and enters the sheath of the rectus
muscle under the semilunar fold of Douglas; it anastomoses

206 ESSENTIALS OF HUMAN ANATOMY.

with the internal mammary and inferior intercostal arteries ;
its branches are :

Cremasteric, Pubic, Muscular, Superficial.

Deep circumflex iliac, arises externally nearly opposite the
epigastric, running along the inner side of the iliac crest, there
to pierce the transversalis and anastomose with the ilio-lumbar
and gluteal arteries. An ascending branch joins the lumbar
and epigastric arteries.

Describe the femoral artery (Fig. 105).

Extending from Poupart's ligament, where the letters N. A.
V. indicate its relation with the anterior crural nerve and
femoral vein, it terminates at the opening in the adductor
magnus (the end of Hunter's canal) ; the upper two-thirds of
a line drawn from the midpoint between the anterior superior
iliac spine and symphysis pubis to the inner side of the internal
condyle of the femur indicates its course. The artery and
vein are enclosed in a strong fibrous sheath, but separated by a
partition from each other, and lie very superficially above, in
Scarpa's triangle, bisecting it.

The femoral artery has three parts : common femoral is one
to two inches long, dividing into the superficial and the deep
femoral (^profunda femoris).

What is Scarpa's triangle ?

It is a space bounded above by Poupart's ligament, inter-
nally by the outer edge of the adductor longus, externally by
the inner edge of the sartorius, the floor being formed by the
iliac, psoas, pectineus, and part of the adductor brevis muscles.

Relations of the common femoral artery : anterior, skin, super-
ficial fascia, superficial inguinal glands, iliac portion of the
fascia lata, anterior part of the femoral sheath from the
transversalis fascia, crural branch of the genito-crural nerve,
superficial circumflex iliac and superficial epigastric veins ;
posterior, posterior part of the femoral sheath from the iliac
fascia, pubic portion of the fascia lata, nerve to the pectineus,
psoas muscle and tendon, pectineus, capsule of the hip-joint ;
internal, femoral vein ; external, anterior crural nerve and
psoas muscle.

Relations of the superficial femoral artery in Scarpa's tri-

THE AKTEKIES.

207

l<m^^

'mdi

#

y/j*p

Fig. 105.— The femoral artery and the side- Fig. 106.— The anterior tibial and
view of the popliteal artery. (Leidy.) the dorsalis pedis arteries.

208 ESSENTIALS OF HUMAN ANATOMY.

angle and Hnntcrs canal: antcrwr^ skin, superficial and deep
fasciae, internal cutaneous and saphenous nerves, sartorius.
aponeurotic covering of Hunter's canal ; po^fcrior. femoral
vein, profunda artery and vein, pectineus, adductor longus and
magnus muscles ; external., long saphenous nerve, nerves to
the vastus internus, vastus internus muscle, and femoral vein ;
internal^ adductor longus, magnus, and sartorius liiuscles.

The femoral artery gives off the following branches :

Snperficial epigastric*^ ^ to the inguinal glands, fascia, and skin,
anastomosing with the superficial branches of the deep epi-
gastric.

Snperficial circumjiex iliac^^ to the skin of the groin, glands
etc., anastomosing with the deep circumflex, iliac, gluteal, and
external circumflex arteries.

Superior external pudic^, to the skin of the genitals, anasto-
mosing with the terminal branches of the internal pudic, its
fellow, the inferior pudic, and the cremasteric arteries.

Inferior external p)vdic^, to the skin of the genitals and peri-
neum, anastomosing with the superficial perineal and superior
external pudic arteries.

Muscular ", to the sartorius and vastus internus.

Anastomotica magna^'\ arises just above Hunter's canal, and
divides into a superficial (cutaneous) and a deep branch,
anastomosing with the internal and superior external articu-
lar, and the anterior tibial recurrent arteries'*.

Profunda femoris"^ ^ springing from the oi ter back part of
the femoral from one to two inches below Poupart's ligament,
terminating at the lower third of the thigh by the small fourth
perforating artery ; it gives off:

External^ and Internal Circumflex^ Four perforating'".

Describe the popliteal artery.

It commences at the opening in the adductor magnus, and
passing obliquely downward and outward behind the knee-
joint, divides opposite the lower border of the popliteus mus-
cle into the anterior and the po.s^mo?- tibial arteries.

Relations : in the upper part of the popliteal space, the three
chief structures are arranged from behind forward and without
inward in a certain order ; first comes the internal popliteal
nerve, next the popliteal vein, deepest and most internal the
popliteal artery ; anterior^ are the femur, posterior ligaments

THE ARTERIES. • Wd

of the knee-joint, a bit of the head of the tibia, popliteal
fascia, and muscle ; posterior, skin, fasciae, semimembranosus,
popliteal vein, internal popliteal nerve, sometimes a twig from
the obturator nerve, inner head of the gastrocnemius, plantaris,
arch of the soleus ; internal, semimembranosus, adductor mag-
nus tendon, internal condyle, inner head of the gastrocnemius,
internal popliteal nerve (below), popliteal vein (below); exter-
nal, biceps, outer condyle, outer head of the gastrocnemius,
plantaris, internal popliteal nerve (above), popliteal vein
(above). Its branches are :

Superior muscular, Superior external articular,

Inferior muscular or sural, Superior internal articular.

Cutaneous, Inferior internal articular,

Azygos articular. Inferior external articular.

These anastomose with the perforating terminal branch of
the profunda, descending branch of the external circumflex,
anastomotica magna, anterior tibial recurrent, and with each
other, except the muscular; the azygos articular enters the
back of the joint to supply the synovial membrane and inter-
articular ligaments.

Describe the anterior tibial artery (Fig. 106).

Commencing at the lower border of the popliteus muscle, pass-
ing between the two heads of the tibialis posticus by the defect
at the upper part of the interosseous membrane, lying upon its
anterior surface and that of the lower third of the tibia, it ter-
minates at the front of the bend of the ankle in the dornaHs
pedis artery ; the anterior tibial nerve lies externally ; branches
are the posterior and anterior tibial recurrent, superior Jibular,
muscular, internal and external malleolar ; the posterior recur-
rent and superior fibular rise from the artery before it pierces
the membrane.

liclations: in front, skin, fasciae, anterior tibial nerve,
tibialis anticus, extensor longus digitorum, extensor longus
hallucis, anterior annular ligament; internally, tibialis anticus,
extensor longus hallucis; r'x^^r//^/////, anterior tibial nerve, ex-
tensor longus digitorum, extensor longus hallucis; behind,
interosseous membrane, tibia, anterior ligament of the ankle-
joint.

14

210 ESSENTIALS OF HUMAN ANATOMY.

Describe the dorsalis pedis artery ^

It extends from the front of the bend of the ankle to the
back part of the first intermetatarsal space, where it divides
into the first dorsal tiifei-osseous^ (dorsalis hallucis), supply-
ing both sides of the great toe and adjoining side of the second;
the plantar digital branch (communicating), dipping down
between the heads of the first dorsal interosseous muscle to
reach the sole of the foot, and form with the external plantar the
plantar arch ; it gives oil" tico digit(d branches^ one for the inner
side of the great toe and one which divides for the contiguous
sides of the great and second toes ; the other branches are the

Tarsal, arching outward across the tarsus.

Metatarsal^, runs anterior to the preceding over the bases of
the metacarpal bones, giving ofi" the second, third, and fourth
dorsal interosseous, from which arise seven dorsal digitals for
the outer three and a half toes. This artery lies upon the
astragalus, navicular, and middle cuneiform bones, and is crossed
by the innermost tendon of the extensor brevis digitorum.

Describe the posterior tibial artery.

It extends as a large vessel obliquely downward from the
lower border of the popliteus muscle along the tibial side of
the leg to the midpoint of the depression between the inner
ankle and heel, where, beneath the abductor hallucis muscle, it
divides into the internal and the external plantar ; the posterior
tibial nerve lies first to its inner side, but soon crosses it, to
remain close to the outer side ; it gives off the

Perone(tl, along the back of the fibular side of the leg,
brandies of which are muscular, medidlary to the fibula, com-
municating, anterior peroneal, posterior p)Groneal, and external
calcaneal. The anterior peroneal anastomoses with the exter-
nal malleolar, tarsal, and posterior peroneal arteries. The pero-
neal artery is enveloped by the flexor longus hallucis muscle.

The posterior tibial also gives off" muscular branches, medid-
lary to the tibia, cutaneous, communicating, and internal malle-
olar; internal calcane(d u^ViSiWy covciQ ^vom. the external plantar.

Communicating, to the peroneal, passing transversely across
the back of the tibia about two inches above the ankle.

Relations : in front, tibialis posticus, flexor longus digi-
torum, tibia, ankle-joint; internally/, posterior tibial nerve
(upper third) ; externally, posterior tibial nerve (lower two-

THE ARTERIES. 211

thirds) ; behind, skin, fasciae, gastrocnemius, soleus, deep trans-
verse fascia, posterior tibial nerve.

Describe the internal plantar artery.

The smaller terminal of the posterior tibial runs along the
inner side of the foot and great toe, giving off muscular, cuta-
neous, and articular branches.

Describe the external plantar artery.

It passes obliquely outward and forward to the base of the
fifth metatarsal, whence it curves inward to the interval be-
tween the bases of the first and second metatarsal bones, there
anastomosing with the plantar digital branch of the dorsalis
pedis, completing the plantar arch ; the branches given off in
its course to the fifth metatarsal bone are the internal calcaneal,
muscular, and cutaneous.

Internal calcaneal, several large branches to the inner mus-
cles of the sole, fat and skin of the heel, anastomosing with the
peroneal, internal malleolar, and external calcaneal.

The branches of the plantar arch are :

Three posterior perforating, passing up the three outer inter-
metatarsal spaces to anastomose with the interosseous from
the metatarsal.

Four digitals, by division supplying both sides of the three
outer toes, and the outer side of the second — both sides of the
great and the inner side of the second toe being supplied by
the plantar digital branch of the dorsalis pedis.

The digitals give off three anterior j^erf orating arteries near
their bifurcations into the collateral digitals.

Surgical Anatomy of the Arteries.

The student must remember that while all the anastomosing
vessels coming off above and below the site of ligature enlarge,
and should, therefore, be carefully impressed upon the mind
whore enumerated in the preceding pages, yet the blood, by
dissection, has been found to pass chiefly by the vessels men-
tioned under each caption.

Describe the collateral circulation after ligature of the com-
mon carotid.
The chi(!f coniniunications are between the superior and
inferior thyroids, the profunda cervicis of the subclavian, and

212 ESSENTIALS OF HUMAN ANATOMY.

princeps cervicis of the occipital, the vertebral taking the place
of the internal carotid within the cranium.

After ligature of the subclavian (third part).

Between the suprascapular and the posterior scapular with
the subscapular, the internal mammary, and the long and supe-
rior thoracic and subscapular.

After ligature of the axillary.

If below the acromio-thoracic, chiefly between the subscapular
and the other scapular arteries of the subclavian and long
thoracic, through the intercostals with the internal mammary ;
if below the subscapular, the posterior circumflex anastomosing
with the suprascapular and acromio-thoracic, and-inosculations
between the subscapular and the superior profunda.

After ligature of the brachial.

(1) Upper third, by anastomoses between the circumflex and
subscapular and superior profunda ; (2) below the profunda
arteries, by branches of the profundae anastomosing with the
recurrents of the ulnar, radial, and interosseous arteries.

When the thoracic aorta is obliterated.

The internal mammary anastomosing with the intercostals ;
phrenic with the musculo-phrenic, comes nervi phrenici and
deep epigastric, superior intercostal and first aortic intercostal ;
inferior thyroid with the first aortic intercostal ; trans versalis
colli with the posterior branches of the intercostals ; axillary
and subclavian branches to the side of the chest with the lateral
branches of the intercostals.

When the abdominal aorta is tied.

The deep epigastric communicating with the internal mam-
mary, the intercommunications of the superior and inferior
mesenteric, or the latter with the internal pudic, and the
anastomoses of the lumbar with the branches of the internal
iliac.

After the common iliac is tied.

The anastomosis of hemorrhoidal branches of the internal
iliac with the superior hemorrhoidal from the inferior mesen-
teric, the inosculations of the uterine and ovarian, and of the

THE VEINS. 213

vesicalsof opposite sides, that of the lateral sacral with the middle
sacral, of the epigastric with the internal mammary, intercostal
and lumbar, of the ilio-lumbar with the last lumbar, of the
obturators with one another and the deep epigastrics, of the
gluteal with the lateral sacral branches.

After the internal iliac is tied.

Same as above, except that the obturator also communicates
with the internal circumflex, the circumflex and perforating
branches of the profunda with the sciatic, and the circumflex
iliac with the ilio-lumbar and gluteal.

After the external iliac is tied.

The anastomoses between the ilio-lumbar and the circumflex
iliac ; the gluteal and external circumflex ; the obturator and
internal circumflex ; the sciatic with the superior perforating
and the two circumflex arteries ; the internal pudic with the
external pudic and internal circumflex.

After the common femoral is tied.

Anastomoses of gluteal and circumflex iliac with the exter-
nal circumflex ; obturator and sciatic with internal circumflex ;
ilio-lumbar with the external circumflex ; comes nervi ischiadici
with the muscular branches of the popliteal.

After the superficial femoral is tied.

Branches from the profunda anastomosing with the superior
and inferior articular of the knee, anastomotica magna, mus-
cular, and origins of the anterior and posterior tibial.

(The popliteal is never tied except for a wound, when the
articular arteries, anastomotica magna, recurrent tibials, per-
forating and muscular branches would convey the blood.)

The Veins.

Describe the veins.

They are vessels returning venous blood — /. e. blood sur-
charged with carbonic acid gas — to the heart, and have 4^he
same coats as arteries, but not so thick, especially the middle,
in consefjuence collapsing when divided. One set of veins only
carries other than venous blood, viz. the pulmonary convey-
ing arterial blood from the lungs to the left auricle. Certain of
the veins, usually the superficial, have their lining membrane

214 ESSENTIALS OF HUMAN ANATOMY.

forming semilunar redujilications or valves, arranged in pairs
opposite one another, which prevent any reflux of blood. The
large arteries are accompanied by deep veins of the same
name, generally included in the same sheath, while such ves-
sels as the brachial, radial, ulnar, etc. have two veins each,
called vense comites. The superficial veins run between the
layers of the superficial fascia, terminating in the deep veins,
and are not usually accompanied by arteries. All veins freely
anastomose, and even those dignified with special names have
very irregular origins and distributions.

What are sinuses?

A'enous channels, found only within the skull, formed by a
separation of the layers of the dura mater, and lined with
endothelium continuous with that of the veins.

How are the veins classed?

As belonging to the pulmonary , systemic, and portal systems,
the latter an appendage of the systemic.

Name the principal veins which have no valves.

The venfe cav93, hepatic, portal, renal, uterine, ovarian,
cerebral, spinal, and pulmonary.

Name the veins of the head and neck.

(1) Frontal. Facial, Temporo-maxillary,
Supraorbital, Temporal, Posterior auricular.
Angular, Internal Occipital.

maxillary,

(2) Those which return the blood from the head and face :
External jugular, Anterior jugular,
Posterior external jugu- Internal jugular,

lar. Vertebral.

(3) Veins of the cranium : Sunerfie^'al and
Veins of the diploe, Cerebral { Deep,or Venje Galeni.
i^ereDeiiar,

Name the sinuses of the dura mater.

Above and behind, one superior and one inferior longitudinal,
straight, two lateral, two occipital; at the base are two cavernous,
circular^ transverse, two snp>erior and two inferior petrosal.

Eight or nine emissary veins of Santorini aiford communi-

THE VEINS.

215

cation between the sinuses of the dura and the external veins
by the following foramina : mastoid, parietal, j^osterior condylar,
through the external occipital protuherance, foramen ovale,
foramen lacerum, foramen Vesalii, carotid canal, anterior con-
dylar foramina.

How is the internal jugular^ formed (Fig. 107)?

By the junction of the lateral and inferior petrosal sinuses
just outside the jugular foramen ; at the base of the neck the
internal jugular unites with the subclavian vein to form the
innominate vein — at or above the junction is a pair of valves;
into the jugular empty the common facial, lingual, pharyngeal,
superior and middle thyroid veins.

Where do the following veins empty?

The external jugular^, into the subclavian vein external to
the internal jugular ; th.Q posterior external jugular, into the ex-
ternal jugular ; the anterior Jngidar, into the termination of the
external jugular or the subclavian vein ; the vertebral descends
through the vertebral foramina in the transverse processes of
the cervical vertebrae to empty into the back of the innominate
vein, valves guarding the orifice.

Describe the veins of the upper extremity.

They are superficial and deep, the latter being the vense
comites of the arteries ; commencing as digitals, these empty
into the interosseous, these into the palmar until the radial and
idnar comites are formed, which, uniting, form the brachial
venae, comites, consisting of two veins with transverse anasto-
moses. The superficial veins running in the superficial fascia
are called :

Radial

Median

Anterior and
Posterior ulnar

Median cephalic
Median has ilia

Cephalic
Brachial
Basilic

Axillary

Describe the axillary vein.

It is a continuation of the basilic, receiving the brachial and
veins of corresponding names with the arteries of the axilla,
and is continued beneath the clavicle under the name of the
suhclam'an vein^ ; it has valves opposite the lower border of the

216

ESSENTIALS OF HUMAN ANATOMY.

subscapular muscle, also at the mouths of the cephalic and
subscapular veins.

Describe the subclavian vein**.

It extends from the lower border of the first rib to the back
of the sterno-clavicular joint, there uniting with the internal
jugular to form the vena innominata — the subclavian vein lies

in front of the artery with the scalenus
anticus muscle interposed at its second
part ; its tributaries are the external and
the anterior jugular and a tributary of
the cephalic ; on the right side the right
lijmpliatic duct empties at the junction
of the subclavian^ and internal jugular
veins, and at the same point on the left
side the tlioracic duct.

How are the venae innominatse^-^
formed ?

Each by the subclavian and internal
jugular, which unite just below the first
costal cartilage to form the superior vena
cava*; the riglit iimominate is about
one and a half inches long, receiving
blood by the right vertebral, internal
mammary, inferior thyroid, often the
right superior intercostal vein ; the left
vein is larger and about two and one-half
inches long ; the left vertebral, internal
mammary, inferior thyroid, superior in-
tercostal, and occasionally some thymic
and pericardiac veins empty into it.

Describe the superior vena cava*.

It measures from two and a half to
three inches and is formed by the union
of the two innominate veins ^'*'' is half
covered by the pericardium and enters
the upper part of the right auricle ; it returns the blood of
the upper half of the body and receives the vena azygos major
and small mediastinal and pericardiac veins.

Fig. 107.— The veiipe cavse
and azygos veins (Leidy).

THE VEINS. 217

Describe the azygos veins.

They connect the superior and the inferior venae cavae, tak-
ing the place of those vessels in that part of the chest occupied
by the heart.

The right azygos^^ (vena azygos major) commences opposite
the first and second lumbar vertebrae by a tributary from the
right lumbar or renal vein, or from the inferior vena cava,
enters the thorax by the aortic opening, passes to the level
of the fifth rib, and arches over the root of the right lung to
empty into the superior cava, receiving in its course the nine
or ten right lower intercostal veins, the vena azygos minor,
esophageal, mediastinal, and right bronchial veins; also it is
usually connected with the right superior intercostal vein.

The left lower azygos^^ (vena azygos minor) commences by a
tributary from the left lumbar or renal vein, enters the thorax
through the left crus of the diaphragm, passes across from the
left side of the vertebral column at about the ninth thoracic
vertebra to enter the right azygos vein, receiving veins from
three or four lower intercostal spaces, also mediastinal and
esophageal tributaries.

The left upper azygos^' is formed by veins, usually three or
four, from the intercostal spaces between the left superior in-
tercostal and the highest branch of the left lower azygos — ^. e.
from the fourth space to the seventh or eighth inclusive— and
empties into the right azygos or left lower azygos ; it receives
mediastinal tributaries and the left bronchial vein; it is soma-
times absent, its place being taken by the left superior inter-
costal.

Name the other principal veins of the base of the neck ant
of the thorax.

Internal mammary, Mediastinal,

Inferior thyroid, Pericardiac,

Liter costals. Bronchial.

Briefly describe the spinal veins.

They are the dorsi-.y>i,i(tl on the exterior of the spinal col-
umn, forming plexuses around the vertebral spines, laminae,
and processes, emptying into the vertebral, intercostal, lumbar,
and sacral veins respectively.

218 ESSENTIALS OF HUMAN ANATOMY.

The meningo-racMdian, lying between the vertebrae and theca
spinalis, forming plexuses, one running along the posterior sur-
faces of the vertebral bodies, forming two anterior loiic/Ltadiual
veins receiving the venae basis vertebrarum,the other on the inner
surfaces of the lamina, forming two posterior longitadiiial veins,
both extending the whole length of the spinal canal ; the pos-
terior emptying into the dorsi-spinal, the anterior into the ver-
tebral, intercostal, lumbar, and sacral veins respectively.

The vense basis vertehrarum lie in the vertebral bodies and
empty into the anterior longitudinal veins.

The medidli-spinal, those of the cord itself, form a minute
plexus over the cord between the pia mater and the arachnoid,
and near the base of the skull converge to form two or three
trunks terminating in the inferior cerebellar veins or petrosal
sinuses.

Describe the chief veins of the lower extremity.

They are deep and superficial ; the former commence as the
venae comites of the digitals, which form the interosseous ; these
form the anterior^ posterior tibial, and peroneal comites of the
same named arteries, which uniting, form the popliteal, in the
thigh to be called the femoral, being joined by the profunda
femoris and the internal saphenous veins, which again changes
its name to the external iliac above Poupart's ligament ; into
the external iliac empty the deep epigastric and deep circum-
flex iliac veins.

The superficial veins are the

Internal or long saphenous, commencing on the inner side of
the dorsum of the foot, running up in front of the inner mal-
leolus on the inside of the leg and thigh to enter the femoral
vein after passing through the saphenous opening of the fascia
lata ; its tributaries are :

Cutaneous, Superficial circumflex iliac,

Com.municating, External pudic,

Superficial epigastric, Anterior and posterior vein.

External or short saphenous commences at the outer side of
the dorsum of the foot, passes behind the external malleolus,
and up the middle of the leg posteriorly to empty into the pop-
liteal vein between the heads of the gastrocnemius.

THE VEINS. 219

Describe the internal iliac vein.

It is formed by the venae comites of all branches of the in-
ternal iliac artery except the umbilical, and unites opposite the
sacro-iliac articulation with the external iliac vein to form the
common iliac vein; it receives the following veins:

Gluteal, Lateral sacral,

Sciatic Uterine and vaginal plexuses,

Dorsal vein of penis or clitoris, in female,

Internal pudic, Vesico-prostatic pdexus, in male,

Obturator, Hemorrhoidal pdexus.

The portal and general venous systems meet in the hemor-
rhoidal plexus.

Describe the common iliac veins.

Formed by the junction of the external and internal iliac
veins, and receiving the ilio-lumbar, occasionally the lateral
sacral, the left iliac receiving the middle sacral vein, they
unite at an angle upon the intervertebral substance between
the fourth and fifth lumbar vertebrae to form the inferior vena
cava.

Describe the inferior vena cava^

It runs upward from the junction of the two common iliacs,
along the riaht side of the aorta, grooves the liver, pierces the
central tendon of the diaphragm, and terminates at the back
and lower part of the right auricle, being enclosed by the
serous layer of the pericardium ; it returns the blood from all
parts below the diaphragm, and receives the following tribu-
taries :

Tjiimlmr, RenaP,^ Hepatic,

Right spermatic. Right suprarenal, Right common iliac,

Right ovarian, Inferior jdirenic, Left common iliac.

Describe the portal system of veins.

Formed by the union behind the head of the pancreas of the
superior and inferior mesenteric, splenic, and gastric veins, col-
lecting the blood from the viscera of digestion ; the resulting
ported vein divides in the transverse fissure of the liver into a
branch each for the right and left lobe, which ramify to form a
venous plexus in the liver-tissue; the hepatic artery sends

220 ESSENTIALS OF HUMAN ANATOMY.

branclies within the liver to the portal vein, and external to
the organ the vein receives the pyloric and the coronary veins ;
the portal blood is returned to the inferior vena cava by the
hepatic veins.

Name the cardiac veins.

Anterior or ffreat cardiac vein, Right or small coronary sinus,
Middle cardiac vein, Left or great coronary sinus,

Left or posterior cardiac veins, Venae Thehesii.
Right or anterior cardiac veins,

What is the coronary sinus?

A dilatation of about one inch of the anterior cardiac vein
in the posterior part of the left auriculo-ventricular groove,
covered by the left auricle, receiving the posterior and middle
cardiac veins, right sinus, and an oblique vein of Marshall from
the back of the left auricle ; its cardiac orifice is guarded by
the coronary valve.

Describe the pulmonary veins.

Commencing in the lung capillaries they form a main vein
for each lobule, which unite into two trunks for each lung,
opening separately into the left auricle ; at times there are
three veins on the right side, or the two left may terminate
by a common opening.

The Lymphatics.

What are the lymphatics?

Delicate vessels with transparent walls formed of the same
three coats as the arteries and found in all parts of the body
probably, except the nails, cuticle, hair, and cartilage ; they
have numerous valves, producing their characteristic beaded
appearance ; they are supplied with nutrient arteries, but not
with nerves.

What are the iacteals?

The lymphatics of the small intestine, conveying chyle
during digestion, lymph at other times.

Describe the lymphatic glands.

They are small, solid, round, or oval glandular bodies, situated
Id the course of the absorbent vessels which previous to enter-

THE NERVOUS SYSTEM. 221

ing a gland break up into several afferent vessels^ form a plexus
within, and 'emerge by several efferent vessels which soon unite
to form a single trunk ; each gland is surrounded by a fibrous
capsule which sends partitions inward, forming alveoli in which
lies the gland-pulp, or lymphoid tissue, consisting of a rete whose
meshes are filled with lymph-cells. The glands are chiefly
found in the mesentery, along the great vessels, in the medi-
astinum, axilla, neck, at the front of the elbow, groin, and
popliteal space, being usually named from their locality, as
axillary or inguinal.

Describe tlie thoracic duct.

This conveys the bulk of the lymph and chyle into the blood,
being the common lymph-trunk except for the right upper
extremity, right side of the head, neck, and thorax, right lung,
right side of the heart, and convexity of the liver. It commences
(sometimes) by the triangular recepta<uliun chyli, on the front
of the body of the second lumbar vertebra, enters the thorax
by the aortic opening, crosses behind the aorta at the fourth
thoracic vertebra, and opposite the upper border of the seventh
cervical vertebra it curves downward to empty into the junc-
tion of the left internal jugular and subclavian veins. It is
from fifteen to eighteen inches long in the adult.

Describe the right lymphatic duct.

It is about one inch long, receiving lymph from those parts
excepted in the account of the thoracic duct, and empties at the
junction of the right internal jugular and subclavian veins;
both ducts have double semilunar valves at their orifices, pre-
venting regurgitation of blood.

THE NERVOUS SYSTEM.

What are the two divisions of the nervous system ?

The cerehro-spinrd, or that presiding over animal life, and the
sympathetic^ that regulating organic life.

Describe the structure of nerve-tissue.

It is compo.sed chiefly of two structures : the gray or vesicn-
l(ii\ originating impulscH and receiving impressions ; and the
white or yt7y/-c»i<s, conducting impressions; in the sympathetic

222 ESSENTIALS OF HUMAN ANATOMY.

system is found a third structure, gelatinous nerve-tissue ; 75
per cent, of nerve-tissue is composed of water, the remainder
being albumin, phosphorized fat, and salts.

Describe the microscopic structure of white nerve-tissue.

It is formed of tubular fibers, each consisting of a central
axis-cylinder, surrounded by the icliite substance of ScJncaiin,
the whole enclosed by the tubular membrane ov primitive sheath.
A bundle of these fibers invested by a fibro-areolar membrane,
the perineurium (neurilemma', constitutes a nerve, receiving
a special blood-supply by the vasa nervorum ; the gelatinous
variety consists of finely granular fibrillae enclosed in a sheath
— by some these are not considered to be nerves.

Describe gray or vesicular nerve-tissue.

This consists of large granular cells containing nuclei and
nucleoli, ovoid, or with one or many processes (^unipolar, multi-
polar), some of which become continuous with an axis-cylinder.

How do nerves terminate ?

Peripherally sensor}' nerves end in minute plexuses, end-
bulbs, tactile corpuscles, and Pacinian corpuscles; in the special
organs they end in cells and in other not well-ascertained ways;
motor nerves end peripherally in plexuses or by " motorial encl-
plates.^^ The central terminations are not well understood.

What organs compose the cerebro-spinal system?

The brain, spinal cord, and the cranial and spinal nerves.

The membranes of the spinal cord and brain are the dura
mater, the arachnoid, and pia mater.

Describe the cerebral dura mater with its processes.

It is a dense fibrous membrane lining the interior of the
skull, constituting the internal periosteum, is continuous with
that of the spinal cord, and is prolonged to the outer surface
of the skull through the various foramina ; by separation of
its layers the cerebral sinuses are formed ; its smooth under
surface is covered with endothelial cells ; its processes, three
in number, are the

Falx, cerebri, a sickle-shaped layer occupying the longitudi-
nal fissure of the brain : along the upper and lower border
respectively run the superior and inferior longitudinal sinuses.

THE NERVOUS SYSTEM. 223

Tentorium cerehelli^ covering the upper surface of the cere-
bellum ; it supports the weight of the posterior lobes of the
cerebrum ; it is attached to the horizontal arms of the occipital
cross, enclosing the lateral sinuses, to the upper margins of the
petrous bones, including the superior petrosal sinuses, whence
it extends to the anterior and posterior clinoid processes; to
the mid-line above the falx cerebri is attached antero-poste-
riorly, and below medianly is the base of the

Ftdx cereheUi^ a small triangular process passing vertically
between the cerebellar lobes behind.

What are the Pacchionian bodies ?

Numerous aggregations of small whitish granulations of un-
known function found upon the outer surface of the dura
mater near the superior longitudinal sinus, lying in depressions
in the bone, in the superior longitudinal sinus, on the inner
surface of the dura, and on the pia mater ; unknown in infancy,
rare before the third year ; they are enlargements of normal
villi of the arachnoid.

Describe the arachnoid.

It is a delicate membrane lying between the pia mater and
the dura mater, being separated from the latter by the suhdnral
space; it bridges over the convolutions, forming |)rrr/ of the
siiharachnoidean space, and at the base, by being stretched
between the middle lobes, the anterior siibarachnoulean space
is left ; while between the cerebellar hemisphere and the medulla
oblongata lies the p)Osterior siihavftclnioidean space, the two com-
municating across the crura cerebri, and by an opening in its
lower boundary with the fourth ventricle ; these spaces con-
tain the cerebro-spinal fluid, forming an elastic water-cushion
for the encephalon : it consists of interwoven bundles of fibrous
and yellow elastic tissue covered with a layer of endothelium.

What is the pia mater?

It consists of a minute plexus of blood-vessels derived from
the internal carotid and vertebral arteries, held together by
fine areolar tissue; it dips between the convolutions, helps to
form the vclnm intcrpositum and choroid phsxuses of the third
and fourth ventricles, and contains nerves and lymphatics.

224

ESSENTIALS OF HUMAN ANATOMY.

Anterior pri-
mary vesi-
cle, or fore-
brain

' First secondary vesi-
cle (^proseitcepJia-
loii)

The Brain.

The cerebral part of the cerebro-spinal system includes the
medulla oblongata, pons Varolii, cerebellum, and cerebrum. The
upper end of the neural tube develops into three iwlmary
vesicles; next the anterior and posterior vesicles subdivide
and five secoiidari/ vesicles result, each having a cavity and
special derivatives.

The brain should be described in its five parts :

( Anterior end of the
third ventricle, fora-
mina of Monro, lat-
eral ventricles, cere-
bral hemispheres,
olfactory bulbs and
tracts, corpora stri-
ata, corpus callo-
sum, fornix.
Third ventricle, optic
nerves and retinae,
optic thalami, pit-
uitary and pineal
bodies.
Aqueduct of Sylvius,
corpora quadri-

gemina, crura cere-
bri.

Cerebellum.
Pons.

Second secondary
vesicle (jthalameii- <
cephaloii)

Middle pri-
mary vesi- J Third secondary vesi-

cle, or mid-
brain

cle {inesencephaloii)

3. Posterior pri-
mary vesi-
cle, or hind-
brain

Fourth secondary
vesicle (epeit-
cep)lialo\i)

Fifth secondary

vesicle (jneten-
ceplialo)i)

Fourth
ventri-
cle

Medulla ob-
longata.

What is the weight of the brain?

Forty-nine and a half ounces, on the average, in males, and
forty-four ounces in females ; heaviest male brain recorded,
sixty-eight and three-eighths ounces ; lightest, thirty-four
ounces; female brain, heaviest fifty-six ounces, lightest thirty-
one ounces ; idiots' brains seldom weigh more than twenty-
three ounces.

THE BRAIN,

225

Name the fissures and lobes of the cerebrum (Fig. 108).

Each half, or hcmisjjJwre, has its external surface subdivided
into five lobes by three fissures :

Fissure of Sylvius, beginning at the anterior perforated space,
passes to the external surface of the hemisphere and sub-
divides : one arm ascends toward the frontal lobe, and one passes
nearly horizontalli/ backward into the parietal lobe.

The fissure of Rolando commences at or near the middle of
the longitudinal fissure, running downward and forward to a
point a little above the horizontal branch of the Sylvian fissure.

The external parieto-occipital fissure commences about mid-
way between the posterior extremity of the brain and fissure of
Rolando, running downward and forward for a few millimeters.

The frontal lobe lies in front of the fissure of Rolando, and
above the ascending part of the Sylvian fissure ; it has three
surfaces ; its under surface is called the orhital lohe.

Snd. nf CcUioSO

ocafiita.L

^fissure

Fig. 108.— Convolutions and fissures of the outer surface of the cerebral hemi-
sphere.

Tlie parietal lohe is bounded in front by the fissure of Ro-
lando, behind by the external parieto-occipital ^fissure, and
below by the liorizontal limb of the Sylvian fissure,
15

22t) ESSENTIALS OE HUMAN ANATOMY.

The occipital lohc lies behind the external parieto-occipital
fissure.

The teinjmro-sphenoidal lohe occupies the middle cerebral
fossa of the skull, and is limited above and in front by the
Sylvian fissure.

The central lohc^ or island of Reil, lies in the fisisure of
Sylvius at the base of the brain ; the lobes overlapping it are
called opercula.

The inner or median surface of each hemisphere presents
five fissures and about nine gyri or convolutions :

The calloso-inaryiiial fissure (Fig. 109), separating the mar-
ginal convolution from the gyrus fornicatus.

The internal pmrieto-occiprital fissure, a continuation of the
external on the outer surface of the hemisphere.

The calcarine fissure runs from the back of the hemisphere
horizontally forward to the postero-inferior extremity of the
gyrus fornicatus; it is joined by the internal parieto-occipital
fissure.

The collateral fissure runs below and nearly parallel to the
preceding, separated by the infracalcarine or fifth temporal
gyrus.

The dentate fissure commences below the posterior extremity
of the corpus callosum, running forward to end at the recurved
part of the hippocampal gyrus, the uncus. It separates the
dentate gyrus from the hippocampal gyrus.

The transverse fissure, between the temporal lobes and crura
cerebri, fornix, and optic thalami, admits the pia mater into the
lateral ventricles.

Mention the principal convolutions of the brain.

The convolutions, or ff^ri, are elevated ridges covered with
gray matter, separated by deep furrows, or sulci, thus securing
a great extent of gray matter ; while not uniform in all brains,
nor symmetrical, certain principal convolutions are constant,
such as

The gyrus fornicatus, that lying over the corpus callosum.

The marginal, forming the antero-superior margin of the
great longitudinal fissure on the mesial surface of the hemi-
sphere.

The uncinate gyrus includes the hippocampal and infra-
calcarine gyri.

THE BRAIN.

227

The limbic lobe nearly forms a ring around the corpus callo-
sum, its ends being separated by the anterior perforated space ;
the structures forming it are the gyrus fornicatus, hippocampal
gyrus, peduncles of the corpus callosum, fascia dentata, fornix,
the anterior and posterior pillars of the fornix, and one layer of
the septum lucidum. Its boundaries are the calloso-raarginal,
collateral, and post-limbic fissures.

The ascending frontal (Fig. 108), forming the anterior
boundary of the fissure of Rolando.

The ascending parietal, at the posterior boundary of the
same fissure.

The angular gyrus is a part of the inferior parietal convolu-
tion, curving around the extremity of the superior temporal
sulcus.

The supramarginal gyrus lies behind the lower end of the
intraparietal sulcus, arching over the posterior extremity of
the fissure of Sylvius.

Fig. 109.— Convolutions and fissures of the inner surface of the cerebral

hemisphere.

Other convolutions are indicated by the names on the dia-
grams.

Where are the quadrate, cuneate, and paracentral lobes

(Kig. 109) ?

The former is on the mesial surface between the calloso-mar-

228

ESSENTIALS OF HUMAN ANATOMY.

ginal fissure in front and the internal parieto-occipital behind ;
the cuneate lies between the parieto-occipital and the calcarine
fissures ; the paracentral is on the mesial surface around the
upper end of the fissure of Rolando.

Mention structures seen on the under surface of the brain,
in the middle line, and on each side.

Longitudinal Jissure* (Fig. llOj, partially separating the
hemispheres.

3 - 3

Fig. no.— Base of the brain (Leidy).

Rostrum and peduncles of the corpus callosum, which is the
transverse commissure connecting the cerebral hemispheres.

Lamina cincrea -passes forward from the tuber cinereum over
the optic chiasma, turns upward anterior to the third ventricle

THE BRAIN. 229

as the lamina fermi'nalis. and joins the anterior end of the corpus
callosum. The angle at the upward bend is the ojytic recess.

Optic commissure'* J union of the optic tracts, with their par-
tial decussation.

Tuber ctuereum, an eminence of the gray matter, part of the
floor of the third ventricle.

Jn/iincUbulum^, a hollow conical p-rocess of the gray matter
projecting from the middle of the under surface of the tuber
cinereum, communicating with the third ventricle, joining the
posterior lobe of the pituitary body.

Pituitary hody^ a vascular, two-lobed body projecting from
the apex of the infundibulum into the sella turcica of the
sphenoid.

Corpora alhicantia^, are two rounded terminations of the an-
terior crura of the fornix, and of the columns of Yicq d'Azyr
from the optic thalami.

Posterior perforated space^^, between the corpora albicantia
in front, the pons Varolii behind, and the cerebral crura on
either side, forms part of the floor of the third ventricle, and
gives passage for vessels to the optic thalami. It is the ante-
rior part of the substantia nigra.

Tuber annulare of the pons^' and the ventral surface of the
medulla follow.

Laterally are seen the frontal lobe, olfactory bulb, tract, roots,
and the optic tract.

Fissure of Sylvius*, separating by its horizontal limb the
frontal and the parietal lobes from the temporo-sphenoidal ;
its ascending limb passes upward into the inferior frontal con-
volution.

Anterior jyerforated space'', between the roots of the olfactory
nerve on each side for the passage of vessels into the corpus
striatum.

Crus cerebri^^ (|)e<:/?/?tc7e of the cerebrum) connects the cere-
brum with the cerebellum, medulla oblongata, and spinal cord.

Then follow the lower surfaces of the temp>oral lobe and of
the cerebellum..

Name and describe the basal ganglia of the hemispheres.

Tlicy arc near the island of Jicil and form the oldest part of
the brain. They consist of the eorjxn-a sfrifffa, the clausfra, and
amygdaloid nuclei, the optic thalami belonging to the thalamen-

230 ESSENTIALS OF HUMAN ANATOMY.

cephalon, tsenia semicircular is, external and internal capsules,
and anterior commissure.

Corpora striata, chief part of the motor tract, lying in the
lateral ventricles, the intraventricular gray portion called the
caudate nucleus, the extraventricular, the lenticular nucleus, the
internal capsule dividing the two.

The lenticular nucleus is bounded externally by the external
capsule, and that externally by the gray matter called the
claustrum. The caudate nucleus runs downward and forward
in the roof of the descending cornu, and terminates in the nu-
cleus amygdalse in the apex of the temporal lobe.

Each optic thalamus has two rounded extremities, the ante-
rior and the posterior tubercles, the latter being called j^^dvinar,
and four surfaces ; the inferior surface rests on the tegmentum
of the crus cerebri ; the external is in contact with the internal
capsule ; the internal forms the lateral boundary of the third
ventricle ; the upper surface presents a groove for the margin
of the fornix ; the part external to the groove is on the floor
of the body of the lateral ventricle; the part internal is covered
by the velum interpositum. Posteriorly are the external and
internal geniculate bodies.

The tsenia semicirailaris lies in a depression between the
nucleus caudatus and the optic thalamus. In front it joins
the anterior pillar of the fornix ; behind, it enters the nucleus
amygdalae.

What is the internal capsule ?

A large tract of white matter belonging to the pyramidal
tract, consisting of two limbs, the anterior, lying between the
anterior part of the lenticular nucleus and the caudate nucleus,
and the posterior, lying between the posterior part of the len-
ticular nucleus and the optic thalamus, which, by their junction,
form a projection inward, the knee or genu.

What is the external capsule ?

A small tract of white matter lying between the outer part
of the lenticular nucleus and the claustrum.

What are the commissures?

Connecting bands of white or gray matter. Those of white
matter have three sets — 1 , project ion- fibers, which pass from
the mid-brain to the hemispheres and form the corona radiata ;

THE BRAIN. 231

2, transverse or commissural, connecting the hemispheres ; 3,
associatwii-Jibers, on one side of the middle line, which may con-
nect near or distant parts ; short and long fibers are present,
The long fibers are the

Superior longitudinal fasciculus. Uncinate fasciculus,

Inferior longitudinal fasciculus, Fillet of the gi/r us for mea-

tus, or Cingulum,
Perpendicular fasciculus , Fornix.

Other longitudinal bands may be mentioned, not properly
association-fibers — olfactory tracts, taenia semicircularis, crura
cerebri, peduncles of the pineal gland, superior .peduncles of
the cerebellum, gyrus fornicatus.

The transverse Jibers of the white matter are two in number
— 1, transverse fibers of the corpjis callosum ; 2, antenor com-
missure. In addition are the middle, posterior, and optic com-
missures, pons, and fornix.

What are the ventricles of the brain ?

Five serous cavities, four of which intercommunicate ; they
are two lateral, a third, ^fourth, and 2^ fifth.

Describe the lateral ventricles.

The corpus callosum roofs them in ; each has a hody, an an-
terior cornu, curving outward and forward into the frontal lobe,
a middle cornu passing into the temporal lobe /backward, out-
ward, f/ownward, /orward, and mward (J>odfi'), containing the
curved hippocampus major, and a jxjsterior cornu curving back-
ward and inward into the occipital lobe, containing the hippo-
campus minor ; the floor from before backward is formed by
the corpus striatum, tffuia semicircularis, optic tladamus, cho-
roid plexus, corpus fimJyriatuin, half of the hodij and the pos-
terior jn7/«r of the fornix. The septum lucidum is internal.

What are the pes hippocampi and the pes accessorius ?

The former consists of elevations of the lower extremity of
the hippocatnpus major in the floor of the descending cornu.

P<s accessorius, or «minenfia collatcralis, is a white eminence
external to the hippocampus major; it is near the junction of
the nii<l(ll(; and \\\v. posterior horns, and is formed by the inter-
nal projection of the collateral fissure.

232 ESSENTIALS OF HUMAN ANATOMY.

What is the fascia dentata?

It is a free edge of the gray substance of the dentate convo-
lution, seen hy raising the edge of the corpus fimbriatum.

Describe the following parts.

Ol/dctorij ljulbs''\ the ganglia of the sense of smell, lie in the
olfactory grooves of the cribriform plate of the ethmoid, and arise
by two white roots : the ontn- root crosses the fissure of Syl-
vius coming from a nucleus of gray matter in the hippocampal
gyrus ; the inner root comes from the lower end of the gyrus
fornicatus; and the middle or gray root comes from the under
surface of the same lobe.

The corjfiiH ca/fosimi is a thick arched layer of transverse
fibers at the bottom of the longitudinal fissure, anteriorly
curving upon itself, giving off two peduncles to the entrance
of the Sylvian fissure; posteriorly is the spleninm continuous
with the fornix ; a median linear depression on its upper sur-
face is called the raphe, parallel to which on each side run two
or more elevated longitudinal bands, the strise, hngitudinales or
nerves of Lancisi.

Choroid plexus is the vascular margin of the velum inter-
positum, communicating with that of the opposite side just
behind the anterior pillars of the fornix, through the foramina
of Monro; posteriorly, it descends into the middle horn,
becoming there continuous with the pia mater through the
transverse fissure.

Corpus fimhriatum (Jpfmia hipjpjocarnjn) is the lateral edge
of the posterior pillar of the fornix, forming a white band just
behind the choroid plexus ; it is attached to the hippocampus
major and ends at the uncus.

The fornix, continuous with the corpus callosum behind,
consists of two halves forming a triangular hodi/, two anterior
pillars, curving downward to the base of the brain, there to
end in the corpjora alhicantia and not in the optic thalami, and
two p)osterior p)illars, running down the middle cornua of the
lateral ventricles, joining the hippocampn majores and fmhi^ise ;
on the back under surface of the corpus callosum, between the
posterior pillars of the fornix, certain transverse, longitudinal,
and oblique lines have been termed the l?/ra.

The septum lucid inn is a vertical septum, attached above to
the under surface of the corpus callosum. below to the anterior

THE BRAIN. 233

part of the fornix and prolonged portion of the corpus callosum ;
it is triangular in form, and consists of two lamina of white
nerve-matter lined internally with gray matter, the space
between forming the Jifth ventricle, not communicating with
the other ventricles.
Describe the corpora quadrigemina.

These are four rounded projections placed just behind the third
ventricle and the posterior commissure, beneath the posterior bor-
der of the corpus callosum, resting on the lamina quadrigemina,
beneath which in the median line is the aqueduct of Sylvius.
Two white bands on each side connect them with the geniculate
bodies and ojyfic tract; that passing from an anterior quadri-
geminal tubercle, the anterior brachiuni, goes between the inter-
nal geniculate hodij and the posterior extremity of the optic
thalamus to the external geniculate hodij and thence to the optic
tract. The posterior hrachium passes from a posterior quadri-
geminal tubercle and loses itself under the internal geniculate
body. These tubercles seem to be connected with the cerebel-
lum"^ by the superior peduncles, which pass to the optic thalami
through the tegmenta of the crura.

What is the valve of Vieussens ?

A thin lamina of nerve-tissue, stretching from the vermiform
process of the cerebellum from one superior peduncle to the
other, forming the roof of the upper half of the fourth ven-
tricle ; a little ridge descending upon the upper part from the
corpora quadrigemina is the fr;£nuli an, and on either side is the
fourth nerve ; on the upper surface is a grooved lobule of gray
matter — the lingula.

What is the pineal gland?

It is a small reddish body, epiphysis cerebri, behind the poste-
rior commissure, above and between the upper pair of corpora
quadrigemina ; it is attached on each side by a st<dk made of a
dorsid and a ventral lamina separated by the pineal recess : the
former belongs to the posterior commissure; the latter is pro-
longed as the stria pine<dis to the anterior pillar of the fornix.
Laterally the stalk merges into the trigonuin habemdse, a
depression on the upper surface of the optic thalamus.

Describe the third ventricle.

Narrow and oblong, the lateral walls being the optic thalami

234 ESSENTIALS OF HUMAN ANATOMY.

and peduncles of tlie pineal gland ; above, the under surface
of the velum iuterpositum roofs it in, containing the choroid
plexuses of this ventricle; the lamina cinerea, tuber cinereum,
infundibulum. corpora albicantia. posterior perforated space,
and tegmenta form its floor ; it is limited in front by the ante-
rior crura of the fornix and the lamina cinerea ; behind, by the
posterior commissure, beneath which opens the aqueduct of
Sylvius; while in front, b}" the foramina of Monro, it com-
municates with the lateral ventricles ; the cavity is crossed by
an anterior and a posterior white commissure and by a middle
gray commissure.

Describe the fourth ventricle.

It is the space between the posterior surface of the medulla
oblongata and the pons in front and the cerebellum behind.
Its roof is the superior medullary velum or valve of Vieussens,
the tent and the inferior medullary velum ; the lateral boundaries
on each side are above, the superior peduncle of the cerebellum,
below, the clava of the funiculus gracilis, funiculus cuneatus, and
restiform body ; the floor is diamond-shaped, made of two tri-
angles, the lower belongs to the medulla, the upper to the pons ;
below it is continuous with the central canal of the cord, above,
with the aqueduct of Sylvius ; on each side is a lateral recess ;
the lower end is called the calamus scriptorius. and the edge of
epithelium on the margins is the liyula, and at the calamus is
the obex. The floor is bisected by a median groove, from the
middle part of which arise the stri^ medullares, running trans-
versely outward. Below them are three triangles on each side:
internally the trigonum hypogloasi, or fasciculus teres; exter-
nally the trigonum acustici, its base pointing upward; and be-
tween these the trigonum vagi with its apex above. This apex
is the inferior fovea ; the floor and base are the ala, cinerea
and the eminentia cinerea ; from it arise the ninth, tenth, and
eleventh cranial nerves. Above the striae is the superior fovea,
to its inner side is the fasciculus teres continued ; above the
fovea is a groove, the locus coeruleus — the color is due to the
presence of pigmented nerve-cells, the substantia ferrvginea.

Describe the pons Varolii.

It is the ventral portion of the hind-brain, the cerebellum
being the dorsal ; it connects the medulla below with the
crura cerebri. It is about one inch long ; its width is a little

THE BRAIN. 235

greater; it is three-fourths of an inch thick. It has four sur-
faces, the svprrior and the inUrior seen after section, the ven-
tral and the dorsal ; the dorsal forms the upper half of the floor
of the fourth ventricle ; the ventral surface rests on the dorsum
sellae and is grooved by the basilar artery ; it shows well-marked
transverse fibers, which are the middle peduncles of the cere-
helium, or the tuber annulare. The pons has gray matter and
four sets of white fibers, transverse and longitudinal, with
superficial and deep sets in each. The gray matter contains
the nuclei pant is, superior olivary nucleus^ nucleus of the seventh,
two n uclei of the Ji/th, and nuclei of the auditory and sixth nerves.

Describe the medulla oblongata.

The medulla or spinal bulb is the after-Irani connecting the
spinal cord with the pons Varolii and cerebellum. It lies in the
vallecula between the cerebellar hemispheres and rests on the
basilar groove of the occipital bone. It is about one inch long,
three-c^uarters of an inch wide, and three-fifths of an inch thick ;
it has two extremities and four surfaces. It is divided into
symmetrical lateral halves by the anttrior and posterior median
fissures (Figs. 110 and 111). Each lateral surface is marked
oif by a dorso-lateral Siud a ventro-lateral groove.

The lower half of the ventral surface is made up of the crossed
pyramidal tracts of the cord, decussation of the j^yramids. and
laterally by the direct pyramidal tracts. Above, in the upper
half, are the two ^i^ramjWs ; behind each pyramid is the
ventro-lateral groove.

The lateral surface presents, above, the olivary body with its
dentate nucleus ; below is the lateral tract, containing the antero-
lateral ground bundle, antno-lafered ascending and descending
cerebellar tracts of the cord. Supeificial arciform JiLers wind
back over this surface.

The dorsal surface is divided below by the posterior median
fissure and separated from the lateral tract by the dorso-lateral
groove ; it receives the direct cerrhellar tract of the cord pass-
ing into the restiform body. Three columns are between this
tract and the median fissure : externally is the funiculus of
Rohmdo; next, the funiculus cunratus ; 'iBnermost, the funiculus
gracilis. The upper half of the dorsal surf\\ce is the lower half
of the floor of the fourth ventricle, bounded laterally by the res-
tiform bodies, which are the infrior prd uncles of the cerebellum.

236

ESSENTIALS OF HUMAN ANATOMY.

Describe the cerebellum.

It is that portion of the hiiid-hraia contained in the inferior
occipital fossffi composed of lamluse covered with gray matter ;
in the middle line is the worm, laterally are two hemispheres.
It is four inches wide, two inches long, and about two inches
thick ; it weighs five ounces ; its proportion to the cerebrum
is as 1 to 8|-. Above is a median ridge, the superior vermi-
form process ; below is a median fossa, the vallecula, contain-
ino- the inferior vermiform process. In front and behind is a
notch, the incisura cerehelli, anterior and posterior ; the great
horizontal fissure surrounds the cerebellum.

Describe the lobes and sulci of the cerebellum.

Hemisphere.

Worm.

Worm and
Hemisphere.

Sulcus preoentralis
Sulcus postcentralis
Sulcus precllvalis .
Sulcus postclivalis .

Lobus lingulse.

Frsenulum lingulse. Lingula.

Ala lobuli centralis. Lobulus cen- ) Lobus cen-

tralis, r trails.

Lobus lunatus ante- Culmenmon- I Lobus cul-

rior (crescentic). ticuli. ( minis.

Lobus lunatus poste- Clivus nion- t Lobus clivi
rior (crescentic). ticuli. (

Lobus postero-supe- Folium cacu

.1

Sulcus horizontalis ) "'^^-
magnus /

1- Lobus cacu-
I minis.

Lobus semilunaris ^ Tuber val-
inferior. b vulse.

Sulcus postgracilis .

Sulcus intragracilis

Lobulus gracilis o
posterior. S-

Lobulus gracilis 2
anterior. ;;•

Sulcus pregracilis, \ .'^

s. postpyramidalis; -^^— — — — ^-^^— ^-^— — ^

Sulcus prepyrami da- Lobus blventralis Pyramis.
lis . . . .* (digastric).

Lobus tuberis.

(^ Lobus pyrami-
( dis.

Sulcus postnodularis

Amygdala (tonsil). Uvula.

•Lobus uvulse.

Flocculus.

Nodulus.

^ Lobus noduli.

The surfaces of the cerebellum present lohes and interlohular
fissures; the upper surface has five lobes and four fissures ; from

CRANIAL TOPOGRAPHY. 237

before backward, on thp superior worm, they are the lingida, loh-
iilas centralis, cidmen, clivis, and folium cacuminis ; correspond-
ing lobes of the hemisphere are the JriBiiulum, ala, anterior and
posterior crescentic, and poster o-superior. The interlobular fis-
sures are the precentral, postcentral, preclival, and postclivaL On
the lower surface are four lobes and three fissures ; from be-
hind forward on the inferior icorm are the tuber valvulse,, pyra-
mis, uvula, and nodulus ; on the hemisphere are the jyostero-in-
ferior, divisible into the inferior semilunar, posterior and ante-
rior slender, the biventral or digastric^ the amygdala^ and the^oc-
culus. The fissures are the postp)yraniidal, prepyraniidal, and
postnodular. The complete arrangement is a combination of
three lobes, one on each hemisphere and one on the worm,
separated from similar groups by fissures.

How many peduncles has the cerebellum?

Three : the transverse fibers of the pons Varolii, or middle
peduncle; on each side the restiform bodies of the medulla
oblongata, or inferior 2)eduncles ; the superior peduncles run to
the corpora quadrigemina, and help to form the roof of the
fourth ventricle, the valve of Vieussens lying between.

Describe the arrangement of the gray matter of the cere-
bellum.

A vertical section reveals a central stem of white matter
containing a pouch of gray matter, the corpus dentatnm. From
the central white stem ten or twelve plates, or hmiinse, spring,
covered externally by a layer of gray matter, so that the cut
surface presents the appearance called arbor vitse. Special nu-
clei are the nucleus emboliformis, globosus, fastigii, or nucleus of
the roof.

Cranial Topography.

Certain important advances have recently been made in cere-
bral surgery ; the student of anatomy should note some of the
contributing causes, such as the localization of brain-centers
and their relations to cranial surfaces. Certain guide-points are
agreed upon, as the glabella, the smooth eminence between the
ridges for the eyebrows; nasion, the center of the naso-frontal
suture; inion, the external occipital protuberance ; landxla, at
the superior angle of the occipital bone, 6 cm. (nearly 2^
inches) above the inion ; orbital arch, external angular process,
mastoid process, external auditory meatus, superior nuchal

238 ESSENTIALS OF HUMAN ANATOMY.

(curved) line^ parietal eminence, zygoma^ sutures, are all used
as landmarks.

The middle meningeal artery is opposite a point in the tem-
poral fossa at equal distances, one inch, one and a half, or two
inches above the zygoma and the same distance behind the ex-
ternal angular process of the frontal bone.

The mastoid antrum and site of operation on the same is
one-third to one-half inch behind, and the same distance above
the center of the external auditory meatus.

Fissure of Rolando : draw a line from the naso-frontal
groove, nasion, to the inion ; a point taken on this line 1 cm. (^
inch) behind its center, or 55.6 per cent, of the distance from
the glabella, will indicate the superior Rolandic point. Draw the
Rolandic line downward and forward for a distance of 8.6 cm.
(o|- inches), at a Rolandic angle of 71.5'^ with the mesial line,
often given as 67°, but it varies from 6-1:° to 75°. If the inion
cannot be easily felt, the upper end of the llolandic line may be
practically found by measuring back from the nasion 18 cm.
in case of large heads, 17 cm. in small ones. The fissure of
Rolando is not quite so long as the Rolandic line, and the ends
of the fissure do not quite correspond with the superior and
the lower Rolandic points. The precentrcd and postcentral sulci
are nearly parallel with this fissure, and 15 mm. distant.

Another method is Reid's : he first marks the longitudinal
fissure and horizontal limb of the fissure of Sylvius ; Reid's
base-line passes from the infraorbital margin, and is continued
through the middle of the external auditory meatus ; it is hor-
izontal ; from it are (Jrawn two perpendicular lines to the top
of the cranium , one from the preauricular j^oint, which is a
depres.sion between the tragus of the ear and the condyle of
the jaw, and one from the posterior border of the base of the
mastoid process. A four-sided figure is thus formed and a
diagonal from its postero-superior angle downward to the an-
terior perpendicular line where it crosses the fissure of Sylvius
will represent the fissure of Rolando.

The supjerior Rolandic point may be found, of course, by the
first method, and only one vertical line of Reid, the preauricu-
lar, be used to determine the lower Rolandic point.

The fissure of Sylvius ('Reid's description) may be marked
by a line drawn from a point one and one-fourth inches behind
the external angular process of the frontal bone to a point

THE SPINAL CORD. 239

three-fourths of an inch below the most prominent part of the
parietal eminence ; the first three-fourths of an inch represents
the main fissure, and the rest the horizontal limb ; the bifurca-
tion of the fissure is therefore two inches behind and slightly
above the level of the external angular process.

Another description (Quain) difiers somewhat from the above
in regard to measurements : carry a horizontal line backward
from the fronto-malar junction (external angular process; for
35 mm. (1|^ inches), and from the outer end of this draw a
vertical line upward for 12 mm. (i inch) ; the upper end of
the latter marks the Sylvian j^oinf, the bifurcation of the Syl-
vian fissure ; it lies under the posterior part of the sphenoparietal
suture. A straight line drawn from the fronto-malar junction
through the Sylvian point goes to the lower part of the parie-
tal eminence and about overlies the posterior limb of the fis-
sure ; it is called the Sjjlvian line. The ascending limb is
marked by a line 2 cm. long, starting from the Sylvian point
directed upward and forward, at a right angle to the Sylvian
line, crossing the coronal suture obliquely ; the undivided main
fissure passes horizontally forward beneath the spheno-parietal
suture in the region of the pterion.

The lower Roland ic point is on the Sylvian line, 25 mm. be-
hind the Sylvian point; it is 5.5 cm. (4 to 7 cm.) above the
zygoma and on the vertical preauricular line. The fissure of
Rolando ends about 1 cm. above this spot.

The parallel fissure of the temporo-sphenoidal lobe is indi-
cated by a line drawn from the marginal tubercle on the pos-
tero-superior border of the malar bone to the lambda.

The parieto-occipital fissure is one-fifth of an inch above the
lambda, or 6.5 cm. (more than 2\ inches) above the inion;
draw a transverse line of 2 cm. to represent it.

The Spinal Cord.

What is the spinal cord?

The elongated cylindrical part of the cerebro-spinal axis con-
tained in the vertebral canal, measuring sixteen and one-fourth
to seventeen and one-half inches in length, extending from the
lower margin of the foramen magnum to the lower border of the
first lumbar vertebra, presenting a cervical enlargement from the
third cervical to the first or second thoracic vertebra, and a
lumbar enlargement opposite the two or three last thoracic ver-

240 ESSENTIALS OF HUMAN ANATOMY,

tebn« ; it becomes the conns medullaris and ends by a filament,
Jilnni tcrniinale. The white matter is disposed externally, the
gray internally in the form of two crescents joined by a trans-
verse commissure, the anterior thicker extremities forming the
anterior cornna, or horiia, the posterior forming the i^ostcrior
coriiua.

Describe the membranes of the cord.

Three : the dura mater, continuous with that of the brain,
but separated from the bony walls by loose areolar tissue, con-
taining a plexus of veins ; the arachnoid, continuous with the
cerebral arachnoid, also having a snhdural and a suharach-
noidean space, the latter communicating with the general
ventricular cavity of the brain by the foramen of 3Iajemlie, an
aperture in the pia mater of the fourth ventricle — this space
contains an abundant serous secretion, the cerehro-spmal flnid;
and the pm mater, sending a fold down into the anterior
median fissure, not posterior, having medianly in front a
fibrous band, the linca splendent, and on each side another, the
ligamentum doiticulatiim, whose outer border presents twenty-
one serrations, the apices of each being attached to the inner
surface of the dura mater, serving to support the cord.

Describe the fissures.

They are the anterior and the posterior median, dividing the
cord into two lateral halves, joined by a white and a gray com-
missure ; on each side of the anterior fissure is a series of
foramina for the exit of the anterior roots of the nerves ; this
line of openings is called the anterodateral groove ; a postero-
lateral groove runs parallel to the posterior median fissure on
each side for the entrance of the posterior roots; a delicate
groove between the postero-lateral groove and the posterior
median fissure exists, the posterior mtermediate furrow, most
marked in the cervical region.

Name the columns of the cord marked off by these fissures.
One plan is to make three columns for each half — anterior,
lateral, and posterior. It is better to disregard the antero-
lateral groove, making three columns — antero-lateral, postero-
lateral, and posterior median. The antero-lateral column
includes more than two-thirds of the surface, passing from the
anterior median fissure to the postero-lateral groove ; the

THE CRANIAL NERVES.

241

postero-laferal column includes the part between the postero-
lateral groove and the posterior intermediate furrow ; the j^oste-
rior median column is between the posterior intermediate fur-
row and the posterior median fissure.

What is the ventricle of the cord ?

The fetal central canal, usually obliterated, runs in the gray
commissure the whole length of the cord, enlarged below,
and opens into the fourth ventricle above.

The Cranial Nerves.

Describe them.

The cranial nerves number twelve pairs, named in the order
of their passage through the cranial foramina; other names
are given according to their
function or distribution.
Each has its superficial ori-
gin, but also some special cen-
ter, called the nucleus : this
is the deep or real origin.

First, Olfactory' (Fig.
Ill), nerves of smell ; super-
ficial origin, from the olfac-
tory bulb, a lobe of the brain,
which is the termination of
the olfactory tract, having
three roots (p. 232) , one from
the temporal lobe, one from
the frontal, and one from the
gyrus fornicatus ; twenty
non - medullated filaments
pass in three groups through
the foramina in the cribri-
form plate to the upper part
of the nasal mucous mem-
brane, to the cells of Schvltze.

Second, Optic", nerve of
sight ; deep origin Jvmn the ^^^ ^^^ ,^.,_^, ^^^^.^^^ ,^^.^^.^,^ ^^ ^^^^ ^^^^
optic tracts " , winch arise of the brain (Lcidy).

from the optic thai ami, cor-
pora geniculata; and superior pair of the corpora quadrigemina ;

16

242

ESSENTIALS OF HUMAN ANATOMY.

is also attached to the cms cerebri and receives fibers from the
tuber cinereum and lamina cinerea ; in front of the tuber cine-
reum lies the optic chiasma or commissure, formed of six sets of
fibers, viz. a set crossing from the right side of the brain to the left
eye ; a second pursuing the same course from the opposite side,
decussating fibers ; a third, anterior, connecting the two retinae,
interretiiial fibers ; a fourth and fifth, lateral, cerebro-retinal,
connecting the hemisphere of one side with the retina of the
eye of the same side ; a sixth intercerehral set, Gudden's com-

FiG. 112.— The distribution of the three divisions of the fifth nerve (Leidy).

missure, which connects the internal geniculate bodies and the
inferior rjuadrigeminal tubercles; distribution, retina.

Third'". Motor oculi ; superficial origin, inner surface of the
crus cerebri ; eleep origin., a nucleus in the floor of the aque-
duct of Sylvius ; escapes in two branches by the sphenoidal
fissure ; distribution, to all eye-muscles, including the iris and
ciliary mu.scle. except the external rectus and superior oblique.

Fourth ''■, Trochlear, Patheticus. motor ; superficial rjrigin,
valve of Vieussens ; deep origin, floor of the aqueduct of Syl-

THE CEANIAL NERVES. 243

vius ; escapes through the sphenoidal fissure ; distribution^ to
the superior oblique of the eye.

Fifth '■, Trigeminus or Trifacial, nerve of general sensation,
motion, and perhaps taste ; superjicial origin^ by a motor and a
sensory root from the side of the pons Varolii ; deep origin^
sensory root from the nucleus in the pons just below the floor
of the upper half of the fourth ventricle ; the Gasserian gan-
glion formed on this root lies on the apex of the petrous por-
tion of the temporal bone ; the motor root arises from a mass
of gray cells to the inner side of the nucleus of the sensory
root; escapes^ ophthalmic^ division (Fig. 112), by the sphe-
noidal fissure, superior maxillary * by the foramen rotundum,
inferior maxillary ° by the foramen ovale.

Ophthalmic division^ (Fig. H-), purely sensory, supplies
the eyeball, ciliary muscle, iris, lacrimal gland, nasal and
ocular mucous membrane, skin and muscles of the eyebrow,
forehead and nose, ciliary ganglion and dura ; its branches are :

Frontal, Lacrimal, Nasal,

Meningeal or (nervus tentorii).

Superior maxillary division* (Fig. 112), sensory, is dis-
tributed to the temple, cheek, lower ej^elid, nose, upper lip and
teeth, and, by ^leckel's ganglion connected with this nerve, to
the palate and pharynx ; its branches are :
Meningeal^ Two sjyheno-jmlafine,

Orbital or temporo-malar, C Palpebral,

C Anterior, Infraorbital < Nasal,

Superior dental I Middle, (^ Labial.

(^ Postei'ior.

Inferior maxillary division ^ (Fig. 112), nerve of common
sensation and motion ; supplies the muscles of mastication,
teeth, gums, skin of the temple and of the external ear, lower
part of the face and lower lip, the tongue, otic and sub-
maxillary ganglia ; its branches are :

Meningeal (iiervus spmosus), Auricnlo-temporal,

Masseteric, Lingual,

Tliree deep temporal, ( Mi/lo-Jnjoid,

Buccal (sf')iHor?/), r r • T A i\ Dental,

rr, . - -7 Inferior dental

Iwo pterygoids, -'

hici^or,
Mental.

244 ESSENTIALS UF HUMAN ANATOMY.

Describe the cranial and facial ganglia.

The Gassf ridii gan(/liiin is convex anteriorly, rests between
two layers of the dura in the cavum M( ckdli on the apex of
the petrous portion ; under it are the motor root and the large
superficial petrosal nerve ; it gives off meningeal branches and
three divisions of the fifth nerve, the inferior one joining the
motor root.

The ciliarij or oplitludmic ganglion is in the orbit.

The sjjJieno-palatuie ganglion (Meckel's) is in the spheno-
maxillary fossa.

The otic ganglion (Arnold's) is on the inner side of the infe-
rior maxillary nerve below the foramen ovale.

Ganglia are occasionally found on the middle meningeal,
lingual, temporal, and pharyngeal arteries, receiving the name
of their location or discoverer, as Bidder or Cloquet.

The ganglion of Bochdalek is situated in the external wall of
the antrum, at the junction of the middle and anterior superior
dental nerves from the infraorbital ; the ganglion of Valentin is
at the junction of the middle and posterior superior dental.

The suhmaxillary ganglion lies above the deep portion of the
submaxillary gland.

Describe the ciliary ganglion.

Situated in the orbit between the optic nerve and the external
rectus muscle ; its roots are : sensor ij^irom. the nasal branch of
the ophthalmic (fifth pair) ; motor, branch of the tLird nerve to
the inferior oblique muscle ; sympathetic, cavernous plexus ; its
hranches are : short ciliary in two bundles of twelve to twenty
twigs to the ciliary muscle, iris, and cornea.

Describe the spheno-palatine ganglion.

Deeply placed in the spheno-maxillary fossa ; its roots are
sensory, from the superior maxillary ; motor, facial, through
the large superficial petrosal ; sympathetic, from the carotid
plexus, through the large deep petrosal ; its branches are :

Ascending, Pharyngeal, or Pterygo-palatine,

Anterior palatine, Superior nasal (^anterior).

Posterior palatine, Su2:>erior nasal (posterior),

External palatine, Naso-palatine.

Describe the otic ganglion.

It lies beneath the foramen ovale, internal to the inferior

THE CRANIAL NERVES. 245

maxillary nerve, external to the Elustachian tube and in front
of the middle meningeal artery. Its motor and senmrij roots
come from the nerve to the internal pterygoid, sympathetic
from the middle meningeal plexus ; it connects with the facial
and glosso-pharyngeal, and gives a sjyhenoidid twig to the A idian.
Branches pass to the auriculo-temporal, chorda tympani, and
buccal nerves, to the internal pterygoid, tensor palati, and ten-
sor tympani muscles.

Describe the submaxillary ganglion.

Situated above the deep portion of the submaxillary gland ;
its roots are : sensory, from the lingual nerve ; motor, facial,
through the chorda tympani ; sympathetic, from the facial
plexus ; its branches go to the mucous membrane of the
mouth, to the submaxillary gland, and to its duct.

Describe the petrosal nerves.

The great petrosal (large superficial petrosal) may be de-
scribed as a branch of the splieno-palatine ganglion passing
through the Vidian canal, distributing twigs to the mucous
membrane of the back part of the nose, septum, and p]ustachian
tube, passing longitudinally through the foramen lacerum
medium, where it divides into the large superficial petrosal,
which enters the hiatus Fallopii, receives a twig from Jacob-
son's nerve, and terminates in the geniculate ganglion of the
facial nerve, and the carotid (large deep petrosal) joining the
carotid plexus.

Small superficial jietrosal connects the geniculate ganglion of
the seventh nerve and the tympanic plexus with the otic gan-
glion.

External jyetrosal (external superficial petrosal) passes from
the geniculate ganglion of the seventh nerve to the middle
meningeal plexus.

More correctly, the large superficial petrosal and the large
deep petrosal may be said to form the Vidian nerve, which
runs forward through the same named canal to join the spheno-
palatine ganglion, supplying it with motor and sympathetic
fibers. According to this description, the twigs said to be
given off by the \'idian nerve to the nasal mucous membrane
must be considered branches of the ganglion running back in
the same sheath.

246 ESSENTIALS OF HUMAN ANATOMY.

Sixth, Abducens"'' (Fig. Ill), motor; sitperfjcial origin^ he.-
tween the anterior pyramid and the pons Varolii ; deep origin^
from the nucleus in the fasciculus teres on the upper half of
the floor of the fourth ventricle ; escapes, by the sphenoidal
fissure ; distribution, external rectus muscle.

Seventh, Facial^" (Fig. HI), or portio dura of the seventh
nerve, the motor nerve of all muscles of expression, of the
platysma, buccinator, the muscles of the external ear, posterior
belly of the digastric, stylo-hyoid, stapedius, through the chorda
tympani the lingualis, according to some through the great
superficial petrosal, the levator palati, and the azygos uvulae
muscles ; supei-Jicial or igin jmeduWsi, from the groove between the
olivary and restiform bodies ; deep origin, from the nucleus in
the formatio reticularis of the pons below the floor of the fourth
ventricle arching over the nucleus of the sixth nerve ; escapes
by the internal auditory meatus to the aqu^eductus Fallopii,
and thence by the stylo-mastoid foramen ; distribution, to mus-
cles already mentioned ; its branches are :

Tympanic (to stapedius), ( Temporal,

Chorda tympani, Temporo-facial X Malar,

Posterior auricular, {^Infraorbital,

n* /.• (Buccal,

u. 1 I '-7 Cervico- facial < Suprar}iaxillary ,

l^atylo-hyoid, '' I r r -n

^ ^ ' {^InjramaxiUary.

The communications of the facial are :

With the auditory nerve : Meckel's ganglion by the large
superficial petrosal ; otic ganglion by the small superficial
petrosal ; sympathetic on the middle meningeal by the external
petrosal nerve ; with the pneumogastric, glosso-pharyngeal,
carotid plexus, auricularis niagnus, auriculo-temporal, and with
the three divisions of the fifth nerve.

Eighth, Auditory ''", portio mollis, nerve of hearing ; it begins
by two roots, the mesial (anterior) emerges from the groove
between the olivary and restiform bodies at the lower border
of the pons; deep origin, dorsal auditory nucleus under the tri-
gonum acustici ; the lateral root (posterior) passes around the
outer side of the restiform body and appears to be continuous
with the striae medullares ; escapes by the internal auditory
meatus ; distribution, to the internal ear ; its branches are :

THE CRANIAL NERVES, 247

Vestibular, to the vestibule,
Cochlear, to the cochlea (see p. 374).

Ninth, Glosso-ph.aryngeaP"''' (Fig. Ill), nerve of common
sensation and taste; superjicial or/^/y^, medulla in the groove
just behind the olivary body ; deep origin, gray nucleus at the
inferior fovea in the lower half of the floor of the fourth ven-
tricle ; escapes at the central part of the jugular foramen, after
which it presents two gangliform enlargements, the Jngular and
petrosal ganglia; distribution, to the muscles of the pharynx,
mucous membrane of the pharynx, fauces, tonsil, tongue, and
the middle ear ; its branches are :

Tympanic (Jacobson's), Pharyngeal, Tonsillar,

Carotid, Muscular, Lingual.

Tenth, Pneumogastric'^ (Fig- HI), nervus vagvs, has an ex-
tensive distribution both motor and sensory ; superficial origin,
from the lateral tract of the medulla oblongata behind the
olivary body and below the glosso-pharyngeal ; deep origin,
ala cinerea in the lower part of the floor of the fourth ventricle
— the motor filaments probably come from the spinal accessory ;
escaj)es by the jugular foramen, presenting a gangliform en-
largement, ganglion of the root, and lower another, ganglion of
the trunk; distrihution, to the organs of the voice and respira-
tion, the pharynx, esophagus, stomach, and heart ; the branches
are :

Meningeal, Thoracic cardiac,

Anricidar, Anterior pidmonary,

Pharyngeal, Posterior pulmonary^

Superior laryngeal, Esophageal,

Recurrent laryngeal, Gastric,

Cervical cardiac. Abdominal p>lexuses.

Eleventh, Spinal accessory"', is a motor nerve, spinal part to
two muscles, accessory part to the vagus ; superficial origin,
lateral tracts of the medulla oblongata below the roots of the
vagus, and from the same part of the spinal cord to the fifth
or sixth cervical vertebra ; deep origin, gray matter below the
nu(;]('us of the vagus and int(!rmedio-lateral tract of the cord ;
it sends filaments to the ganglion of the root of the vagus, to
the pharyngeal and superior laryngeal branches of the same

248 ESSENTIALS OF HUMAN ANATOMY.

nerve ; escapes by the jugular foramen, the spinal portion first
entering the skull through the foramen magnum ; disfri/nifion,
to the sterno-mastoid and trapezius, muscles of the larynx, of
the soft palate, except the tensor palati, constrictors of the
pharynx, inhibitory fibers to the heart.

Twelfth, Hypoglossal''" (Fig. Ill), motor nerve of the
tongue ; Hiipcrjicidl origin^ groove between the pyramid and oliv-
ary body in the line of the anterior nerve-roots ; deep origin., tri-
gonum hypoglossi on the floor of the fourth ventricle ; escapes
by the anterior condyloid foramen ; branches are meningeal,
vascular, muscular ; latter to the intrinsic fibers of the tongue,
lingualis, hyo-, stylo-, and genio-hyoglossus ; it communicates
with the tenth, lingual, three upper cervical, and sympathetic
nerves ; the descendens cervicalis from the first and second cer-
vicals runs in the sheath of the hypoglossal ; the communicans
cervicalis, rising from the second and third cervicals meets the
descendens in a loop, ansa cervicalis; these three cervicals
supply the genio-hyoid and the infrahyoid group of muscles.

The Spinal Nerves.

How many pairs of spinal nerves are there ?

Eight cervical, twelve thoracic, five lumbar, five sacral, and
one coccygeal — thirty-one in all.

Describe their origin.

Each nerve arises by an anterior motor root, emerging from
the antero-lateral groove, and a posterior sensory entering the
postero-lateral groove ; these perforate the dura, the posterior
develops a ganglion, and they unite to pass through the inter-
vertebral foramina — except the first cervical, which emerges
above the atlas — after which they break up into anterior and
posterior divisions, the latter, the smaller, supplying the spine,
dorsal muscles, and integument, while the anterior larger
divisions form plexuses whence the remainder of the trunk
and the limbs receive their nerve-supply.

Describe the cervical plexus with its branches.

It is formed by the anterior divisions of the four upper cer-
vical nerves lying upon the levator scapulae and scalenus
medius muscles ; its branches are the superfcial and deep :

THE SPINAL NERVES.

249

Ascending
Descending

Svperjicialis colli,
Auricular is mag-

uus,
Occijjif ((lis minor. Internal ^
Suprasterrud,
Supraclavicula /•,
Supra-acromial.

External

'' Communicating ,
Muscular.
Communicans cer-
vical is.
Descendejis cervi-

calis,
Phren ic.
j Communicating,
I Muscular.

Describe the phrenic nerve.

It arises cliiefly from the fourth cervical nerve with branches
from the third and fifth, runs obUquely over the scalenus
anticus muscle, passes between the subclavian artery and
vein, enters the chest anterior to the internal mammary artery,
to be distributed to the pericardium, pleura, and under surface
of the diaphragm and phrenic plexus; Luschka describes
twigs to the peritoneum, inferior vena cava, and right auricle
of the heart; it is joined by filaments from the sympathetic,
from the nerve to the subclavius muscle, and one from the
union of the descendens cervicalis with the spinal nerves.

Describe the brachial plexus with its branches.

It is formed by the union of the anterior trunks of the four
lower cervical and first thoracic nerves ; four special names are
used— anterior nerves form trunks, trunks form divisions or
branches and these form cords. The fifth and sixth cervical
nerves join and form an upjyer trunk ; the eighth cervical and
first thoracic unite and form a loicer trunk ; the seventh remains
single and forms a middle trunk ; each trunk divides into an ante-
rior find a posterior division; the anterior divisions of the upper
and middle trunks unite and form the oiiter cord; the anterior
division of the lower trunk forms by itself the inner cord, and
the posterior divisions of all three form the posterior cord;
sometimes the posterior division of tlie lower trunk does not
meet the other two, but runs lower down into the musculo-
spiral nerve. From the outer cord arise the external anterior
thoracic nerve, nerve to the coraco-bracbialis, musculo-cutaneous,
and the outer head of the median ; from the inner cord arise the
internal anterior thoracic, lesser internal cutaneous, internal
cutaneous, ulnar, and inner head of the median ; from the ^>as-

/

250 ESSENTIALS OF HUMAN ANATOMY.

terior coy(/ arise three subscapular nerves, the circumflex, and the
musculo-spiral. Branches of communication are with the fourth
cervical, second thoracic, phrenic, and sympathetic system ;
hrancJiea of clistrihutioa are (I) to the muscles of the trunk,
(II) of the shoulder girdle, and (III) of the upper extremity.

(I) Mmcular to the longus colli and three scaleni ; lower
part of scalenus anticus and medius ; whole of scalenus posticus.

(II) 1. Twig to the rhomboidei from the fifth cervical.

2. Posterior or long thoracic^ from the fifth, sixth, and
seventh nerves, to the serratus magnus muscle.

3. Suprascapular, from the upper trunk ; to the supra and
infraspinatus muscles and shoulder-joint.

4. Nerve to the subclavius from the upper trunk, mainly from
the fifth.

5. External and internal anterior thoracic, the former from
the outer cord, the latter from the inner cord ; both to the
pectoralis major, the internal to the pectoralis minor.

6. Three subscapular, the upper from the communicating
branch from the outer to the posterior cord, the other two
from the posterior cord ; to the subscapularis, teres major, and
latissimus dorsi muscles.

7. Circumflex, from the posterior cord with the musculo-
spiral ; to the deltoid and teres minor, the shoulder-joint, and
skin of the lower deltoid region.

8. Xerve from the outer cord to the coraco-hrachial is.

(III) There are five anterior arm-nerves, one posterior ; mus-
culo-cutaneous, from the outer cord pierces the coraco-brachialis ;
to biceps, brachialis anticus, and elbow-joint, and skin of the
outer surface of the forearm ; internal cutaneous, from the inner
cord to the skin over the biceps and that of the inner half of the
forearm in front and behind ; lesser internal cutaneous (nerve of
Wrisberg), from the inner cord alone, or a branch from this
joined with the intercosto-humeral, the lateral cutaneous
branch of the second intercostal nerve ; or, again, the intercosto-
humeral may entirely replace it; to the skin of the inner side of
the arm ; median, from the outer and inner cords by two roots
that embrace the axillary artery, uniting in front or to its outer
side, first lying external to the brachial artery, then crossing to
its inner side, passing between the two heads of the pronator
teres muscle to run between the deep and superficial flexors
of the fingers to near the wrist, where it becomes superficial ;

THE SPINAL NERVES. 251

its branches are articalm- to the elbow, wrist, metacarpus, and
fingers ; mascidar^ to all anterior superficial forearm-muscles
except the flexor carpi ulnaris ; anterior interosseous, to the deep
forearm-muscles except the inner half of the flexor profundus
digitorum ; palmar cutaneous, piercing the fascia above the wrist
to the skin of the thenar eminence ; branches to the abductor,
opponens, and outer head of the flexor brevis pollicis ; Jive digi-
tals, supplying both sides of the thumb, index, middle, and radial
side of the ring fingers.

Ulnar, from the inner cord runs behind the inner epicondyle,
passing into the forearm between the heads of the flexor carpi
ulnaris to run some distance from the ulnar artery at the upper
third, but clo.se to it for the rest of its extent ; it supplies both
sides of the little and ulnar side of the ring finger and skin in-
ternally of the forearm and hand ; its branches are articular
for the elbow, wrist, metacarpus, and hand ; muscular, to the
flexor carpi ulnaris, inner half of the flexor profundus digito-
rum, the little finger muscles, the interossei and inner two
lumbricals, palmaris brevis, adductores pollicis, and inner head
of the flexor brevis pollicis.

Names of branches in the forearm are : Articular, muscular,
cutaneous, dorsal cutaneous ; in the \i\}in^\, superficial and deep
palmar.

Musculo-spiral, from the posterior cord, runs in the spiral
groove with the superior profunda vessels to divide in front of
the external condyle of the humerus into the radial and poste-
rior interosseous ; its branches are :

Radial, Muscular,

Posterior interosseous. Cutaneous,

Articular (elbow and wrist).

Radial, to the skin of the ball of the thumb, to back of the
thumb as far as the nail, back of first phalanx of the index
finger, arnl back of the radial half of the first phalanx of the mid-
dle finger; posterior interosseous, supplying the wrist-joint and
all muscles on the back of the forearm except the anconeus,
supinator longus, and extensor carpi radialis longior; muscular,
to the triceps, anconeus, supinator longus, exten.sor carpi radialis
longior, and brachialis anticus ; cutaneous, to the skin of the
outer and Ijack part of the arm and forearm.

252 ESSENTIALS OF HUMAN ANATOMY.

The Thoracic Nerves.

Describe them.

Twelve in number on eacli side, the first escapes between
the first and secund thoracic vertebrc^, the last between the
last thoracic and first lumbar ; they divide into an ante-
rior and a posterior division, the latter supplying the spine,
extensor muscles of the back, and the dorsal integument ;
the former (anterior) are the intercostal nerves^ the twelfth
being called subcostal, each connected by one or two filaments
with the adjacent sympathetic ganglion : the anterior division
of the Jirst nerve aids in the formation of the brachial plexus;
its intercostal branch is small and gives ofi" no lateral cutaneous
branch ; the lateral branch of the second nerve is the intercosto-
humeral ; the nerves give off lateral and anterior cutaneous
branches supplying the skin of the front and sides of the
thorax and abdomen, while they give muscular branches to the
intercostal and abdominal muscles.

Describe the lumbar nerves.

The posterior branches resemble in origin and arrangement
those of the thoracic region, while their anterior branches form
the lumbar and part of the sacral plexuses ; there are five
pairs.

Describe the lumbar plexus and branches.

It is formed by loops of communication between the anterior
divisions of the four upper lumbar nerves in the substance of
the psoas muscle, thus the first lumbar is joined by a branch
from the last thoracic, dorso-lumhar, and gives off the ilio-
hijpogastric and ilio-inguinal and a branch to the genito-crural ;
the second goes to the genito-crural and external cutaneous and
gives a descending branch to the anterior crural and obturator ;
the third gives off three branches, one to the extermd cutaneous,
a large one to the anterior crural, and one to the obturator ;
the fourth has three branches, to the anterior crural, to the
obturator, and one to join the fifth, forming the lumbosacral
cord ; the fourth is called the nervus furcalis, splitting like a
fork for the two plexuses ; the accessory obturator when
present comes from the third and fourth nerves.

Branches of the plexus are: 1. Of communication with the
twelfth thoracic, fifth lumbar, and sympathetic. 2. Of disti-i-

THE SPINAL NERVES. 253

button, short set to the quadratus lumborum. to the psoas magnus
or parvus ; long set to the abdomen and to the thigh, viz. the
ilio-hi/pogastric^illo-ingiiinal, genital part of the genito-crural to
the abdomen ; the anterior crural, external cutaneous, crural
part of the genito-crural and obturator to the thigh.

llio-hypogastric supplies the skin of the gluteal region, skin
and two muscles of the hypogastrium, the internal oblique and
trans versalis ; Uio-inguinal, to the internal oblique and trans-
versalis muscles and skin of the scrotum (labium in the
female), and the upper inner part of the thigh ; external cuta-
neous, to the skin of the antero-external and posterior surfaces
of the thigh ; genito-crural, to the cremaster muscle and skin
of the front of the upper part of the thigh ; obturator, to the
obturator externus and adductor muscles, hip- and knee-joints,
also sometimes to the skin of the thigh and leg.

The accessory obturator is usually lacking ; when present it
comes from the third and fourth lumbar nerves, crosses the
horizontal ramus of the pubes, and divides into three branches :
one to the hip-joint, one to the pectineus, and one to join the
obturator nerve.

Anterior crural, from the third and fourth, with a communi-
cating branch from the second lumbar nerve. It descends
beneath Poupart's ligament external to the femoral artery be-
tween the psoas and iliacus muscles, and divides into an ante-
rior and a posterior division : its branches are, within the pelvis,

Muscular to iliacus, and to the walls of the femoral artery ;
external to the pelvis,

. , . C Middle cutaneous, t> ^ • C Long saphenous,

Anterior ) j , j ^ ' Posterior ) 4 .■ j^

,. • • < J nternat cutaneous, j- • • i Articutar,

division. ] ^r 1 division. ] ,. , '

(^ Muscular. [^ Muscular.

It supplies all the anterior thigh-muscles, except the tensor
fasciae femoris, and the skin of the front and inner side of the
thigh, leg, and foot.

The muscular branches of the anterior division supply the
pectineus and sartorius ; the muscular branches of the poste-
rior division supply the quadriceps femoris ; the nerve to the
rectus sends a filament to the hip-joint, the nerves to the vasti
•send filaments to the knee-joint.

Describe the sacral plexus.

It is formed l^y the lumbo-sacral cord (the anterior division

254 ESSENTIALS OF HUMAN ANATOMY.

of the fifth lumbar nerve with a branch of the fourth), and
anterior divisions of the three upper sacral nerves and part of
that of the fourth ; it rests upon the anterior surface of the
pyriformis muscle, giving off the

Superior gluteal, from the lumbo-sacral cord, passing out
through the greater sacro-sciatic foramen, to the gluteus medius
and minimus and tensor fasciae femoris muscles; the inferior
gluteal nerve supplies the gluteus maximus.

Muscular hranches to the pyriformis, obturator internus and
superior gemellus, to quadratus femoris and inferior gemellus.

Pndic passes out of the pelvis by the greater sacro-sciatic
foramen, to re-enter it by the lesser sacro-sciatic foramen ; its
branches are :

Inferior hemorrhoidal. Perineal, Dorsal of peiLis.

Muscular, to the transversus perinei, accelerator urinae,
erector penis, compressor urethras, levator ani, and external
sphincter : the preceding branches supply analogous muscles
and parts in the female.

Smcdl sciatic escapes by the greater sacro-sciatic foramen, to
the skin of the scrotum, lower part of the buttock, back of the
leg and thigh ; its branches are the gluteal cutaneous, femoral
cutaneous, and inferior pudendal ; no muscular branches.

Great sciatic is a continuation of the main part of the sacral
plexus, forming the largest nerve in the body. Escaping by the
greater sacro-sciatic foramen below the pyriformis muscle, it lies
in a groove between the great trochanter and the tuber ischii,
covered by the gluteus maximus, resting on the obturator in-
ternus, gemelli. and quadratus femoris : its branches are articu-
lar to the hip, muscular to the biceps, semitendinosus, semimem-
branosus, and adductor magnus, and it divides into the internal
and the external popliteal nerves.

Name the branches of the internal popliteal nerve.

Articular to the knee, three in number.

Muscular to the gastrocnemius, plantaris, soleus, and pop-
liteus.

External or sliort saphenous is formed by the junction of a
cutaneous branch, communicans tibialis or poplitei, and another
cutaneous branch of the external popliteal, the communicans
fbularis or peronei.

THE SPINAL NERVES. 255

Describe the posterior tibial nerve.

It is a continuation of the former, runs down the middle of
the back of the leg beneath the calf-muscles to divide between
the inner malleolus and point of the heel into the internal and
external plantar ; its branches are :

Mascnlur^ to the tibialis posticus, flexor luiigus digitorum,
flexor longus hallucis, and the soleus muscles ; articular^ to
the ankle-joint.

Plantar cutaneous^ to the skin of the heel and inner side of
the sole of the foot.

Fibular branchy to the vessels, periosteum, and medullary
canal of the fibula.

Internal plantar, supplying the skin of the sole, tarsal and
metatarsal joints, one or two inner lumbricals, abductor hallu-
cis, flexor brevis hallucis, and digitorum, four digital branches
to both sides of the first, second, and third toes, and inner half
of the fourth.

External plantar, smaller than the preceding, supplying the
flexor accessorius, abductor, and flexor brevis minimi digiti, all
the interossei, two or three outer lumbricals, adductor obliquus,
and transversus hallucis. and the skin of the little toe and the
adjoining side of the fourth toe.

Describe the external popliteal nerve.

It descends obliquely along the outer side of the popliteal
space close to the tendon of the biceps, giving off

Three articular branches to the knee ; a cutaneous branch to
the skin of the postero-external surface of the leg, and a branch,
the communlcans peronel,^ovu\m<^^[)iTt of the external saphenous
nerve : it divides into the

Anterior tibial, about one inch below the head of the fibula,
giving mnscular branches to the tibialis anticus, extensor longus
digitorum, peroneus tertius, extensor longus hallucis, and ex-
tensor brevis digitorum ; articular to the tarsal and metatarsal
joints, and cutaneous to the skin of the adjacent sides of the
great and second toes.

Musculo-cutaneous, giving off muscular branches to the pero-
neus longus and brevis, and ciitaneons to the skin of the
lower part of the leg, and dorsum of the foot and toes, except
the outer side of the little and adjoining sides of the great and
second toes.

256 ESSENTIALS OF HUMAN ANATOMY.

Describe the sacral and coccygeal nerves.

They arc six in number, their long roots forming the
Cauda equina in the spinal canal ; each divides into an ante-
rior and a pos^eno?" division, the latter escaping by the
posterior sacral foramina, except the fifth, which emerges
between the sacram and coccyx, and supplies the multifidus
spinaB muscle and the skin of the posterior gluteal region ; a
branch goes from the third and fourth nerves to the bladder ;
the two lower nerves join with the coccygeal, forming loops,
which supply the skin over the coccygeal region and the coccy-
geus, levator ani, and sphincter ani muscles.

The Sympathetic System.

What is the sympathetic nerye or system?

It consists of (1) a series of ganglia with intervening longi-
tudinal bands, forming two cords, ono on each side of the spinal
column connected above according to some by the ganglion of
RiheSj and below by the ganglion impar or coccygeal ganglion,
in front of the coccyx ; (2) three prevertebral plexuses, one
each for the thorax, abdomen, and pelvis; (3) small ganglia;
(4) nerve-fibers of communication with the cerebro-spinal
nerves, of distribution supplying the viscera and vessels.

Describe the cervical ganglia.

There are three on either side, viz. the

Superior cervical ganglion. It is placed opposite the second
and third cervical vertebrae behind the carotid sheath, and
gives off a

Superior branch to the internal carotid artery, forming by
its division the cavernous plexus and carotid plexus (with
their subdivisions) ;

Descending branch, connecting the superior with the middle
ganglion ;

External branches to the cranial and spinal nerves, and an-
terior branches forming plexuses on the external carotid and its
branches ;

Pharyngeal, forming with branches from the spinal acces-
sory, pneumogastric, glosso-pharyngeal, and external laryn-
geal nerves, the pArn^/^^ec// p/f'x^^s ; laryngeal, uniting with
the superior laryngeal nerve and its branches ;

Superior cardiac, connected with other branches of the sym-

THE SYMPATHETIC SYSTEM. 257

pathetic, and with some of the pneumogastrie, passes to the
back of the aorta, the right joining the deep, and the left
(usually) the superjicidl cardiac plexus.

Middle cervical ganglion is placed opposite the sixth cervical
vertebra ; and by its

Superior and inferior branches it communicates respectively
with the superior and the inferior cervical ganglia ; the exter-
nal filaments join the fifth and sixth cervical nerves, the internal
are the thyroid to the inferior thyroid artery and thyroid gland,
and the middle or great cardiac nerve, communicating with other
sympathetic branches and the recurrent laryngeal, to terminate
in the deep cardiac plexus.

Inferior cerviccd ganglion is placed between the base of the
transverse process of the seventh cervical vertebra and neck
of the first rib on the inner side of the superior intercostal
artery ; its superior and inferior branches connect it respectively
with the middle cervical and the first thoracic ganglion ; the
external branches join the spinal nerves, others form a plexus
on the vertebral artery ; its chief branch is the

Inferior cardiac nerve, communicating with the recurrent
laryngeal and middle cardiac nerves, terminating in the deep
cardiac plexus.

What is the carotid plexus?

It is a plexus situated on the outer side of the internal caro-
tid artery communicating with the Gasserian and spheno-pala-
tine ganglia, the sixth nerve, and the tympanic branch of the
glosso-pharyngeal ; it supplies the carotid artery and dura mater.

What is the cavernous plexus?

It is one situated below and internal to that part of the in-
ternal carotid artery running alongside of the sella turcica, in
the cavernous sinus; it communicates with the third, fourth,
fifth, and sixth nerves, and ophthalmic ganglion, and supplying
the carotid, it, with the carotid plexus, forms plexuses embrac-
ing the cerebral and ophthalmic arteries.

What are the other ganglia of the sympathetic system?

I'sually cluvun thoracic, four lumbar, four or five sacral,
ganglion impar, and numerous ganglia connected with the
various viscera, whence! ])lexuses are formed named from their
locality or the organ involved.
17

258 ESSE>'TIALS OF HUMAN ANATOMY.

What are the branches of the thoracic portion ?

Contiiuniicafiiif/. witli one uiiutlier luid the thoracic spinal
nerves, fihinients to the aorta aud its divisions and to the pos-
terior pulmonary plexus, and

The (/rrdf uphincJuiic nerve, formed by the internal branches
from the thoracic ganglia between the fifth or sixth and ninth or
tenth inclusive : it perforates the crus of the diaphragm to ter-
minate in the semilunar ganglion, sending branches to the renal
plexus and suprarenal capsule.

The snidU aphi aclinic, springing from the ninth and tenth,
or from the tenth and eleventh ganglia and cord communicat-
ing with the great splanchnic, pierces the diaphragm with the
preceding, to join the celiac plexus.

Smalksf, or renal splanc/uu'c, arises from the last ganglion,
occasionally communicates with the preceding, pierces the dia-
phragm, and terminates in the renal aud lower part of the
celiac plexus.

Describe the solar plexus.

It supplies all the abdominal viscera, consisting of a network
of nerves and ganglia lying in front of the aorta and crura of
the diaphragm, surrounding the celiac axis and root of the
superior mesenteric artery, extending below to the pancreas,
and laterally to the suprarenal capsules. The great splanchnic
and part of the small splanchnic nerves of both sides and the
termination of the right pneumogastric form this plexus, in
conjunction with the two semilunar ganglia, these latter being
large, irregular gangliform masses, composed of smaller ganglia
separated by interspaces, placed by the side of the celiac axis
and superior mesenteric artery, close to the suprarenal capsules,
that on the right lying beneath the vena cava. From this are
derived the following plexuses accompanying the same named
arteries to the various organs :

Phrenic, or diaphragmcitic, Sujyi-arenul,

C Gastric, Renal,

Celiac < Hepatic, Superior inesentericy

(^ Splenic, Spermatic,

Aortic, Inferior mesenteric.

Name some of the more important plexuses.
Tymjninic (see page 370).
Great, or deep cardiac is placed in front of the bifurcation

THE DIGESTIVE ORGANS. 259

of the trachea, and above that of the pulmonary artery, be-
hind the aortic arch, and is formed by all the sympathetic car-
diac nerves (except the left superior) and cardiac branches of
the recurrent laryngeal and pneumogastric (except the left supe-
rior cardiac and the left inferior cardiac of the pneumogastric).

SuperJiciaJ cardiac lies beneath the aortic arch in front of
the right pulmonary artery, and is formed by the left superior
cardiac of the sympathetic, left inferior cardiac of the pneumo-
gastric, and branches from the deep cardiac plexus.

Coronary^ the posterior^ chiefly from the deep, the anterior
from the superficial cardiac plexus.

Aortic^ on the sides and front of the aorta between the
origins of the superior and inferior mesenteric arteries.

Hypogastric, lying in front of the sacrum, between the com-
mon iliac arteries, supplies the pelvic viscera, and is formed by
filaments from the aortic plexus, and from the lumbar and first
two sacral ganglia, contains no ganglia, and divides into two
lateral portions, forming the inferior hypogastric or pelvic
plexuses.

Pelvic plexnms. two in number, lie upon each side of the
rectum and bladder (rectum, vagina, and bladder in females;,
and each is formed by a continuation of the hypogastric plexus
and branches from the second, third, and fourth sacral nerves,
and a few filaments from the sacral ganglia ; the branches
accompany those of the internal iliac artery, and are distributed
to all the pelvic viscera ; their branches are :

Inferior hemorrhoidal plexus^

Vesical plex us, Vaginal plexus,

C Small and large
Prostatic plexus I cavernous nerves Uterine nerves.

(^ to penis.

VISCERAL ANATOMY.

The Digestive Organs.

What is a viscus?

Any of the internal organs with their appendages, contained
within the four cavities, cranial, thoracic, abdominal, or pelvic.

Of what does the digestive apparatus consist ?

or the alimentary canal, a musculo-membranous tube, lined

260

ESSENTIALS OF HUMAN ANATOMY.

with mucous membrane, a])out thirty feet long, extending from
the mouth to the anus, and certain accessory organs.

Name the subdivisions of the alimentary canal.

Mouth, pharynx, esophagus, stomacli, small intestine (duo-
denum, jejunum, ileum), large intestine (cecum, colon, sig-
moid flexure, rectum).

What are the accessory organs?

The teeth, salivary glands (parotid, submaxillary, sublin-
gual), liver, pancreas, and spleen.

The Teeth.

What is their function?

To reduce the food to fragments, thus enabling the digestive
fluids to act to the best advantage. There are two classes :

Temporary^ or milk teefli^ ten in each jaw, viz. four incisors,
two canines, and four molars ;

Permanent teeth^ sixteen in each jaw, viz. four incisors, two
canines, four bicuspids or premolars, and six molars.

The surface of a tooth turned toward the lips or cheeks is
called lahial^ or buccal; toward the tongue is Ungnal ; toward

the mesial line is proximal ; and away
from it is distal.

Of what parts does every tooth consist ?

Of a crojcn, or hocli/ (Fig. 113), that
part projecting above the gum.

JVeck, the constricted portion between
the crown and the fang.

Fang^, or root., that part occupying the
alveolus, held there by the dental perios-
teum lining the socket and investing the
fang ; teeth are steadied by the gums,
composed of dense fibrous tissue covered
with mucous membrane.

Pulp-cavity'^., an interior cavity filled
with the tooth-pulp, a vascular connec-
tive tissue with numerous nerves, both
arteries and nerves reaching the pulp by
a canal opening at the apex of the fang.

Fig. 113.— Vertical sec-
tion of a molar tooth.
(Leidy.)

THE TEETH. 261

Describe the characteristics of each of the four varieties of
teeth.

Incisor, or cutting teeth. The crown is wedge-shaped, convex
111 front, bevelled and slightly concave behind ; the fang is
single, long, conical, and transversely flattened ; the lingual
surface shows a hasal ridge, or cingulum.

Canines. Crown is large, conical, convex in front, rises
above the level of the other teeth ; fang long, conical, com-
pressed laterally ; upper pair are called in common parlance
eye-teeth," the lower " stomach-teeth."

Bicuspids. Crown has two projecting cusps, fang generally
is single, laterally grooved with a bifid apex ; they are also
called premolars; the upper are larger than the lower.

Molars (grinders). Crown nearly cubical, with four cusps
in the upper, and five in the lower molars ; fangs, usually three
for the first two upper, and two for the first two lower molars;
the third molar is called the '' wisdom tooth " (dens sajnenfise),
from its late appearance, and usually has but one fang with
grooves indicating a tendency to the formation of three fangs
in the upper, and two in the lower jaw.

The second temprjrary molar is the largest milk tooth, and is
succeeded by the second permanent bicuspid.

Describe the structure of a tooth.

Each is formed chiefly of

Dentine, or ivory'^, composed of minute, wavy, branching
tubes, called dentinal tuhes, embedded in a hard, homogeneous
tissue, the intertuhular suhstance. The tubules are about 4-5^00"
of an inch in diameter, dividing dichotomou.sly, giving the
wavy appearance of the cut surface, and open into the pulp-
cavity. Chemically dentine consists of twenty-eight parts of
animal and seventy-two of earthy matter.

EnameP forms a thin crust over the crown, is the densest of
all animal tissues, containing only 3.5 per cent, of animal mat-
ter, and is composed of minute parallel hexagonal rods, or
enanu'l columns, about -^-V^ of an inch in diameter, pursuing
a wavy course.

Cement, or crusfa petrosa*, is a layer of true bone commenc-
ing at the neck, covering the fang, and becoming thicker to-
ward its apex.

Pulp, filling the pulp-cavity', consisting of soft, very vascu-

262

ESSENTIALS OF HUMAN ANATOMY.

lar connective tissue, with numerous nerves and cells, the lat-
ter being of two kinds, columnar, called odontohlnsts — arranged
in a layer lining the pulp-cavity — some stellate and fusiform
cells wedged in between these permeate the pulp, having fine
processes, prolonged into the dentinal tubules ; certain fila-
ments in the tubules are Tomes filers.

Whence do teeth obtain their blood- and nerve-supply?

From the alveolar and infraorbital branches of the internal
maxillary, and from the inferior dental artery ; the nerves
come from the anterior and posterior dental branches of the
superior maxillary, and from the inferior maxillary division of
the fifth nerve.

When do the temporary teeth appear?

The time is variable, but, according to the latest authority,
they erupt as follows, expressed in months :

a5

u

C

u

C

OJ

u

tH

C3

o

o

o

o

C

fH

u

e3

OS

m

x

ai

m

(A

03

C

o

C

O

o

O

'S

S

o

o

S

g

o

1— 1

B
8-10

1^

fl
^

6

%

§

Upper

20-24

15-21

16-20

8-10

8-10

8-10

16-20

15-21

20-24

Lower

20-24

15-21

16-20

15-21

6-9

6-9

15-21

16-20

15-21

20-24

The order of their appearance is, first, the lower central in-
cisors ; then the upper central incisors, closely followed b}" the
laterals ; then the lower laterals ; next the upper anterior mo-
lars followed by the lower ; then the upper canines followed by
the lower; finally, the lower back molars, followed by the
upper.

Describe the order of appearance of the permanent teeth.

The first to appear are the first molars at the end of the sixth
year, the lower teeth usually preceding the upper ; thus, ex-
pressed in years., these teeth erupt as follows :

a

o

'CS

'6

-d

i

13

iL

0)

(-

X

0^

^

X

p.

CO

-7^

o

s

c;

"S

O

c

(3

O

o

"r

O

Oi

%

§

7

11

PQ

6

1— 1

5

t— 1

6

10

PQ
11

'^

S

^

Upper .

18-30

13-16

10

11-13

9

8

8

9

11-13

7

13-16

18-30

Lower .

17-25

12-13

6

10

9

11-12

8

7

7

8

11-12

9

10

6

12-13

17-25

THE MOUTH. 263

Describe the development of the teeth.

The enamel is derived from the ectoderm ; the dentin, ce-
mentum. and pulp from the mesoderm. A lineur tliickf^nuig of
oral epithelium appears before the sixth week ; next follows a
lateral (labial) projection, the dental ridge., growing into the
mesoderm, forming a furrow on the oral surface, the dental
groove of Goodsir. The positions of the future teeth are
marked by local thickenings under the ridge, the dental bidbs,
which become the enamel organs of the temporary teeth ; the
dental ridge atrophies ; these primitive enamel organs become
invaginated like an epithelial cap over a mesodermic dental
jjajidl'i^ embracing about two-thirds of it ; the cap shows three
layers — the external, of one or two rows of low columnar cells,
the outer enamel cells; they are reflected to form the inner in-
vaginated layer of the organ, the inner enamel cells. These two
layers are separated at first by a middle layer, which undergoes
great changes : a network is formed, reduced to thin plates,
fluid collects (enamel j^'dp), and finally all disappears. At the
sides of the primitive organs the second enamel organ develops
the permanent teeth. The inner layer above produces enamel,
enamel membrane. The top and sides of the dental papillae are
covered -by odontoblasts, whose processes are dentinal fibers ;
the canals left are dentinal tubules, homologues of the canaliculi
of bone. The central part of a dental papilla remains as pnlp-
tissue. The cementnm is formed last of all from an epithelial
sheath, but not in fetal life, and increases to old age. By the
gradual growth of the fang the crown produces absorption by
pressure upon the overlying bone and mucous membrane, when
eruption occurs.

The Mouth.
What is the mouth?

It is an ovoid cavity in which food is masticated, bounded
by the lips in front, by the cheeks and alveolar processes of
both jaws with their contained teeth at the sides, by the hard
palate above, by the tongue and floor of the mouth below, and
behind by the soft palate and the anterior pillars of the fauces
where it opens into the pharynx ; it is lined by mucous mem-
brane covered by scaly stratified epithelium containing numer-
ous racemose glands, continuous with the skin at the free mar-
gin of the lips; it presents for examination

The hard palate^ formed by the palatal processes of the supe-

264 ESSENTIALS OF HUMAN ANATOMY.

rior maxillary and palate bones covered by the intimately
adherent periosteum and mucous membrane furnished with
palatal glands.

The 8oft palate, consisting of a fold of mucous membrane
depending from the posterior border of the hard palate, en-
closing muscular tissue, an aponeurosis, adenoid tissue, mucous
glands, etc. ; the muscles on each side are five, the levator and
tensor palati. palato-glossus, palato-pharyngeus, and azygos
uvulffi — the latter with its fellow forming the median pro-
jecting conical uvula.

Anterior and posterior jnllars of the fauces., the former con-
taining within a fold of mucous membrane the palato-glossus
muscle on each side, arching downward and forward from the
palate to the base of the tongue ; the latter, the palato-pharyn-
gei muscles, passing backward and downward to the sides of
the pharynx.

Isthmus fauciuui is the space bounded by the pillars of the
fauces and tonsils, base of the tongue, and free margin of the
soft palate.

Tonsils' (Fig. 114). situated between the anterior and the
posterior pillars on each side, consisting of glandular tissue
containing twelve to fifteen openings leading into crypts lined
with mucous membrane, external to which is a layer of closed
capsules analogous to those of Peyer's glands ; the tonsil is
only separated from the internal carotid artery by the superior
constrictor muscle.

Openings of the ducts rf Stensen. opposite the second upper
molar tooth on each side, delivering the secretion of the parotid
glands.

Openings of the ducts of Wharton, one on either side of the
frenum of the tongue, delivering the secretion of the submax-
illary glands.

Openings of the ducts of the suhlingiial gland {ducts of Ri duns'),
from eight to twenty in number ; they open on an elevated
crest of the mucous membrane on each side of the frenum
linguae, one or more joining in a tube opening into Wharton's
duct called the dnct of Bartholin.

What are the salivary glands?

Three compound racemose glands on each side. The parotid,
the largest, lies below and in front of the ear between the

THE MOUTH.

265

zygoma above, mastoid behind, and ramus of the jaw in front
— its duct is Stenseiis; the submaxt'llari/ Vies below the jaw
in the anterior part of the submaxilhiry triangle — its duct is
Wharton's ; the siihlingiud lies beneath the mucous membrane
of the floor of the mouth against the jaw, close to the sym-
physis— its ducts are those of Rivinns.

Describe the tongue.

Its base is attached to the hyoid bone and lower jaw by
muscles, to the epiglottis by two lateral and one median^

Fk;. 111.— Dorsum of the tongue (Lcidy).

266 ESSENTIALS OF HUMAN ANATOMY.

glosso-epiglottic folds of mucous membrane, and to the soft
palate by the anterior pillars; its tip, sides, dorsum, and part
of the under surface are free ; a median raphe and fibrous
septum divide the organ into halves ; its mucous membrane
reflected over the floor of the mouth to the gums forms in
front an antero-posterior fold, the freiiinn lingua ; the tongue
is formed by certain intrinsic muscular fibers, viz. those of the
lingualis, and by extrinsic muscles, the stylo-glossus, hyo-
glossus, genio-hyo-glossus, and palato-glossus (see p. 148).
The mucous membrane of the tongue presents the

CircumvaUdte papillae, numbering eight to ten, arranged on
the back part of the dorsum in two lines converging behind
like a letter V ; just behind the junction is a little recess, the
foramen csecum'\ prolonged in the fetus by the tliyro-glossal
duct to the pyramidal process of the thyroid gland.

Fungiform papillae^, scattered over the dorsum, but chiefly
found at the sides and apex.

Filiform or conical papillse, *, with secondary papillae project-
ing from their apices, arranged in lines cover the anterior two-
thirds of the dorsum of the tongue.

Racemose lingual glands'^, situated along the sides, but
chiefly over the posterior third of the dorsum ; some secrete
mucus, others serum.

Lymphoid tissue, collected into masses or folliclfs, exhibits
crypts ; one collection far back is called the lingual tonsil.

Name the blood-supply.
This is from the :

r Dorsalis linguse, Facial, by the submental
Lingual < Suhlingual, branch anastomosing with

(^ Ranine, the sublingual.

Ascending pharyngeal,

Describe the nerve-supply.

The lingual branch of the fifth is distributed to the papillse
at the front and sides to the extent of two-thirds of its surface,
endowing these parts with general sensation ; the chorda
tymj)ani has the same distribution, and seems to be the nerve
of taste to this region.

Lingufd branch of the glosso-pharyngeal , supplying the
mucous membrane of the base and sides and circumvallate

THE PHARYNX. 267

papilhTS or posterior third ; it is the nerve of taste and sensa-
tion for these parts.

Hypoglossal^ to the muscles ; tlie motor nerve.

Superior laryngeal sends a few filaments to the base near the
epiglottis from its internal branch ; thus, five nerves supply
each side.

What anatomical points of surgical interest does the palate
present in the vicinity of the last molar tooth ?
Just behind this tooth the liamular process and the mfernal
pterygoid plate can be felt, the point for division of the tensor
palati aponeurosis in the operation for cleft palate ; and in front
of this to the inner side of the last molar tooth is the posterior
jKilatine artery as it emerges from the canal, sometimes re-
quiring plugging after a cleft-palate operation ; in resection of
the inferior dental nerve, locate the last molar tooth, enter the
mucous membrane and find the lingula on the ramus of the
jaw which is just above and anterior to the nerve.

The Pharynx.

What is the pharynx ?

A conical musculo-membranous sac, about five inches long,
extending from the under surface of the base of the skull to a
point corresponding to the cricoid cartilage or sixth cervical
vertebra. It is widest opposite the aperture of the larynx,
narrowest below, where it terminates in the esophagus ; it is
bounded ahove by the basilar process and body of "the sphe-
noid; is connected posteriorly with the cervical vertebrae,
longus colli and recti capitis antici muscles ; anteriorly it is
incomplete, opening into the mouth, being attached to the
internal pterygoid process, pterygo-maxillary ligament, lower
jaw, tongue, hyoid bone and larynx ; since it lies behind the
nose, mouth, and larynx, it should be described in three parts
— nasal, oral, laryngeal; laterally, it is attached to the styloid
processes and muscles arising from them, while the common
and internal carotid arteries, the intermil jugular veins, ninth,
tenth, twelfth, and syni])athetic nerves hen; lie in contact with
it. The cavity \\^i!> seven openings: the two posterior nares,
two Eustachian tubes, mouth, larynx, and esophagus. A con-
sider;ibl<; mass of lymphoid tissue extends across tlie back of
the pharynx, between the orific<!S of the Eustachian tubes,

268

ESSENTIALS OF PIUMAN ANATOMY.

called the jiharyngeal tonsil ; a recess in the mucous membrane
always exists in the fetus, the j>h(in/ii(jr(il hnrsfi. which passes
u}» tu the pharyngeal spine ; behind the opening of the Eusta-
chian tube is the fossa of Rosenmiiller ; from the end of the
tube descends a salpingo-plKivijiif/rdl fold of mucous mem-
brane, covering in the salpingo-pltaryiigeus muscle.

Of how many coats does it consist ?

Three : an internal mucous, continuous with that lining: the
mouth, etc., covered with ciliated epithelium down to the level
of the floor of the nares, below by squamous epithelium, con-
taining racemose glands most plentiful around the orifices of
the Eustachian tubes, and much lymphoid tissue surrounding
crypts, called the tubal tonsils ; a middle fibrous coat (^pharyn-
geal ffjioneiirosis), thick above, where the muscular fibers are
wanting; and an external muscular coat composed of the supe-
rior, middle, and inferior constrictors, stylo-pharyngeus. palato-
pharyngeus. and salpingo-pharyngeus muscles.

Describe the pharyngeal muscles Fig. 115).

Inferior constrictor*^: origin, side of the cricoid and thyroid

cartilages; //z>v//'/o/^ unites with its fellow; action, constricts

the pharynx during swallowing ;
nerves, pharyngeal plexus, from
glosso-pharyngeal. external laryngeal,
recurrent laryngeal, spinal accessory.

Middle constrictor": origin, greater
and lesser cornua of the hyoid bone
and stylo-hyoid ligament ; insertion,
unites with its fellow ; action, same
as above ; nerves, glosso-pharyngeal,
spinal accessory through the pharyn-
geal plexus.

Superior constrictor ^"^ : origin, lower
third of the margin of the internal
pterygoid plate and hamular process,
contiguous surface of the palate bone^
reflected tendon of the tensor palati
muscle, pterygo-maxillary ligament,
alveolar process above the posterior
end of the mylo-hyoid ridge and side

of the tongue; insertion, posterior median raphe and pharyn-

FiG. llo.— Muscles of the
pharynx, posterior view.

THE ESOPHAGUS. 269

geal spine of the occipital bone; action, same as the other
constrictors; nerve, spinal accessory through the pharyngeal
plexus.

Stylo-pharyngeus *^ : (jvlglii, inner side of the base of the sty-
loid process; insertion, blends with the constrictor muscles,
and is also inserted into the posterior border of the thyroid
cartilage; action, draws the sides of the pharynx upward and
outward ; nerve, glosso-pharyngeal.

What arteries supply the pharynx?

Superior tlujroid, Tonsillar,

Ascending pharyngeal, Ptery go-palatine, ^

Ascending pjalatine, Descending palatine.

What are its nerves?

Branches from the pharyngeal plexus, formed by the phar-
yngeal branches of the glosso-pharyngeal, pneumogastric, ex-
ternal laryngeal, all derived from the spinal accessory and
sympathetic nerves.

The Esophagus.

Describe it with coats, vessels, and nerves.

It is a muscular canal, nine or ten inches long (23-26 cm.),
joining the pharynx and stomach, commencing at the lower
border of the cricoid cartilage, passing through the esophageal
opening of the diaphragm, to terminate at the cardiac orifice
of the stomach, opposite the eleventh thoracic vertebra; it has
three parts : the cervical, to the opening of the thorax ; the thor-
acic, from the second thoracic vertebra to the tenth ; the ahdom-
inal, about one inch long below the diaphragm ; it has three
curves, one antero-posterior and two lateral ; in the neck it lies
between the trachea and the spinal column and longus colli
muscle, at the lower part inclining to the left, having on either
side the common carotid artery, with the lateral lobes of the
thyroid gland — the recurrent laryngeal nerves ascend between it
and the trachea ; in the thorax, after passing behind the aortic
arch, it runs to the right of the vessel, to pass in front and to
the left again before piercing tlie diapliragm.

It has three coats : internal mucous, when empty thrown into
longitudinal folds, containing numerous glands, its surface being

270 ESSENTIALS OF HUMAN ANATOMY.

studded with small papilla), and covered by squamous epithe-
lium ; at its lower end the next coat is the niuscalarts mucome ;
a middle areolar coat loosely connects the mucous and the
succeeding coat; a niuscnhir, composiid of an external longi-
tudinal and internal circular layer, the fibers ahoce consisting
chiefly of the striated, but below almost entirely of the unstriped
involuntary variety.

The arteries are from the inferior th^Toid, thoracic aorta, left
inferior phrenic, and coronary of the stomach ; they have a
ongitudinal direction.

The veuLS empty into the inferior thyroid, azygos minor, and
coronary of the stomach ; the portal and the general system
meet on the esophagus.

The nerves are from the esophageal plexus, formed by the
pneumogastric and recurrent laryngeals, with some sympathetic
filaments.

The Stomach.

Describe it.

The stomach is a pear-shaped dilatation of the alimentary
canal connecting the esophagus with the small intestine. Its
larger end points above and to the left ; its smaller, below and
to the right. The mouth of the stomach receiving the esopha-
gus is called the eardia. To the left and below this is the
fundus, forming about one-fifth of the stomach ; this continues
on the right into the hod?/ of the stomach, which has two sur-
faces included between two borders ; the anterior surface looks
upward and forward, the posterior, downward and backward ;
the lesser curvature is concave above and to the right, and is
attached to the liver by the lesser omentum ; the greater curva-
ture is convex, turned to the left and downward, and gives
attachment to the great omentum. At the right and lower
end of the stomach the body contracts into the pyloric jwrtion,
which presents two or three bulging parts, each one called the
pyloric antrum ; these pouches are caused by the ^\iori pyloric
ligaments. The external constriction between the stomach and
the duodenum is the pyloric sulcus, made by a muscular ring, the
pyloric sphincter ; an internal projection of the mucous mem-
brane is produced, called the pyloric Vfdve or pylorus. The
peritoneum related consists of the lesser, great, and gastro-
splenic omenta, and a gastro-phrenic ligament.

THE STOMACH. 271

Dimensions and Position. — Length, ten to twelve inches ;
vertical diameter, four to five inches ; antero-posterior, three
and one-half inches ; distance between the two orifices, three
to six inches. ]juschka's measurements of the same lines are :
3-t cm., 15 cm., 3.7 to 11.5 cm. Weight is four and one-half
ounces ; capacity, five to eight pints.

The stomach lies in the epigastrium and the left hypo-
chondrium ; five-sixths are to the left of the median line ; only a
small part of the pyloric portion is on the right side. It lies
under the liver and diaphragm, above the jejunum, ileum, and
colon, and extends from the spleen to the gall-bladder.

The cardia lies one inch (2-3 cm.) below the esophageal
opening in the diaphragm, 11 cm. from the anterior body-wall ;
this point is also opposite the seventh left chondro-sternal
junction or the eleventh thoracic vertebra — three landmarks.
The fundus is 3-5 cm. higher up, at the sixth left chondro-
sternal junction. Pylorus reaches the upper border of the
first lumbar vertebra on the right side. Lowest edge of the
greater curvature in the median line reaches a point two
fingers' breadth above the umbilicus.

Relations: above and anferiorbj, diaphragm, anterior parts
of the seventh, eighth, and ninth ribs, thoracic and abdominal
walls, left part of the under surface of the liver ; posteriorly^
diaphragm and its left crus, aorta, inferior vena cava, celiac
axis, lesser sac of the peritoneum, transverse colon, and splenic
flexure, transverse meso-colon (upper layer), part of the spleen,
splenic vessels, pancreas, left kidney and capsule; at the left
end are the spleen and diaphragm.

How many coats has the stomacli ?

Four, as follows :

Serous, derived from the peritoneum covering all parts
except along the greater and lesser curvatures, where the
omenta leave triangular spaces, along which pass the vessels
and nerves.

Muscular, consisting of three sets of fibers: the longitudinal^
continuous with the longitudinal coat of the esophagus and
small intestine, more distinct along the lesser curvature ; the
circular fihers form a continuous layer beneath the former set,
most abundant at the pyloric end, forming the sphincter; the
oblieiue fibers, some passing obli({uely from left to right, others

272 ESSENTIALS OF HUMAN ANATOMY.

vice versa, around the cardiac orifice ; the submucous coat con-
sists of areolar tissue supporting tlie vessels.

Mucous, covered with columnar epithelium, and thrown into
longitudinal folds or rug;ie when the stomach is empty, covered
by small, shallow, polygonal-shaped alveoli from 0.12 mm. to
0.25 mm. in diameter ; they are the mouths of the tubular
glands.

The gastric glands are of three kinds : the cardiac (not called
peptic) are lined throughout with columnar epithelium, con-
sisting of a duct into which open two or three cecal tubes;
beneath the epithelium lie large, spheroidal, granular, jjarietal
cells ; these glands are found in all parts of the stomach.

Pyloric glands, found in greatest numbers at the pyloric end,
resemble the preceding, but are without the large parietal cells,
and the cecal tubes are shorter and more numerous.

Lenticular glands or lymphoid follicles exist in early life,
consisting of masses of lymphoid tissue like a solitary gland.

Give the blood- and nerve-supply.

The five arteries are : coronary, pyloric, right gastro-epiploic
of the hepatic, left gastro-epiploic, and vasa brevia from the
splenic.

The veins end in the splenic, superior mesenteric, gastric,
and portal veins.

The nerves are the terminal branches of both pneumogastrics
and numerous branches from the sympathetic of the solar
plexus.

The Small Intestine.
Describe it (Fig. 116).

It is the narrowest part of the digestive tract, is a convo-
luted tube twenty-two feet long, occupying the central and
lower parts of the abdominal and pelvic cavities, and is sus-
pended from the spine by a fold of peritoneum called the mes-
entery ; its three divisions are the

Duodenum'^, ten to twelve inches long, with three types, cir-
cular, or infantile, \}-shaped, and y-shap>ed, passing upward and
backward to the right to the under surface of the liver and
gall-bladder — superior curve — then descending in front of the
right kidney — descending portion — thence running transversely
across the third or fourth lumbar y^xX^hxix^transverse portion —

THE SMALL INTESTINE.

273

to endin the jejunum on the left side of the first or second lum-
bar vertebra — ascending portion — a fifth portion is sometimes
described, about one inch long, which arches forward to join the
jejunum. It is only partially covered by peritoneum, has no
mesentery, and surrounds the
head of the pancreas ; into the
descending portion, to the inner
side, pass obliquely the common
bile and pancreatic ducts.

Jejunum^ ^ so called because
usually empty after death, in-
cludes the upper two-fifths of
the remainder of the small intes-
tine, and lies chiefly in the um-
bilical region and left iliac fossa.

Ueura^ includes the remainder
(three-fifths) of the small intes-
tine, is named from its numerous
coils, occupies chiefly the umbil-
ical, hypogastric, right iliac, and
occasionally pelvic regions, and
opens into the inner side of the
commencement of the large in-
testine in the right iliac fossa ;
the orifice is guarded by a two-
leaved ileo-cecal valve, or valve of
Bauliin.

What coats has the small intes-

tme . Yio. 116.— The intestinal canal.

J he same as the stomach — (Lei.iy.)

mucous, submucous, muscular, and serous.

The mucous memhrane is covered with columnar epithelium,
and forms transverse folds encircling the tube for one-half or
two-thirds of its circumference, forming the

I'alculfn conniventes ; they are absent in the first two inches
of the duodenum and almost disappear in the lower part of the
ileum ; villi cover the surface, formed of a central lacteal ves-
sel accompanied by unstriped muscular tissue, an encircling
plexus of ca[)illaries, lymphoid tissue, and granular corpuscles,
all enclosed by a basement-membrane supporting columnar
epithelium: their number is estimated at four million; the

18

274 ESSENTIALS OF HUMAN ANATOMY.

Si(hmiicoiis coat connects the mucous with the muscular coat,
and contains the intestinal vessels and nerve-plexuses ; the

Muscular coat externally is composed of longitudinal and
internally of circular libers, Ibrming complete rings.

Describe the glands of the small intestine.

They are :

BrunnerH ghuuh, resembling the salivary in structure, are
limited to the duodenum and commencement of the jejunum.

Ci'i/pts, or glaiuh of Licbcrk'dliii^ are minute tubular depres-
sions lined with columnar epithelium, found in both intestines,
small and large.

Solltari/ glanth^ most numerous in the lower part of the
ileum, but found in all parts, consist of masses of lymphoid
tissue like a l^mph-node, O.G mm. to 3 mm. in diameter.

Pcyers glands or patclics are twenty to thirty ovoidal patches
composed of numerous solitary glands (hence named agminated
glands), situated opposite to the mesenteric attachment, their
lonu' axis leno-thwise, and are lariiiest and most numerous in the
ileum, although occasionally seen in the jejunum and duo-
denum ; the valvulae conniventes and villi cease at the margins
of the patches.

Name the blood-vessels and nerves.

The arteries are the pyloric and from the gastro-duodenal
of the hepatic and superior mesenteric ; the veins chiefly
empty into the portal system ; the nerves are from the supe-
rior mesenteric plexus of the sympathetic.

The Large Intestine.

Describe it^^^ MFig- H^)-

It extends from the ileum to the anus, is five or six feet
long, large and sacculated, and has the same coats as the small
intestine; the mucous coat is destitute of villi, but is thrown
into crescentic folds by the longitudinal muscular fibers, which
are disposed in three bands (taenia), shorter than the other
coats, so forming them into pouches.

Describe the subdivisions of the colon.

They are the cecum^, or cajmt coll, the dilated commence-

THE LARGE INTESTINE. 275

ment of the large bowel situated in the right iliac fossa, and
usually wholly covered by peritoneum.

The appendix vermi/ormis'^, a narrow, blind-ended, worm-
like tube, from three to six inches long, springing from the
lower back part of the cecum, held in no set position by a
peritoneal fold.

The ileo-cecal valve (or Bauhin's) is formed by two hori-
zontal semilunar folds of mucous membrane at the termination
of the ileum in the cecum, opening toward the large intestine
and guarding against reflux from the large into the small
bowel ; the mucous folds are reinforced by circular muscular
fibers, and the surfaces toward the ileum are covered with
villi, while these are absent on the cecal side.

The ascending colon '' extends up from the cecum in front of
the right kidney, to the under surface of the liver to the right
of the gall-bladder, where, abruptly bending to the left, it forms
the h'pafic flexure; it is almost — sometimes entirely — en-
veloped in peritoneum, in which latter event it has an ascend-
ing meso-colon (26 per cent.).

The transverse colon ^ traverses the abdomen from right to
left, just below the liver, stomach, and spleen, to the left hypo-
chondriac region, where it curves downward beneath the lower
end of the spleen, forming the splenic flexure ; it has a- wide
transverse meso-colon^ attaching it to the spine and pancreas.

The descending colon "^ passes down in front of the left kid-
ney to the left iliac fossa and is only partially covered with
peritoneum, its posterior surface usually being free; the de-
scending meso-colon is rare.

The sigmoid flexure^^^ the narrowest part, lies in the left
iliac fossa extending from the descending colon at the crest of
the ileum to the left sacro-iliac synchondrosis ; it is curved like
an S, and is held in place by a loose peritoneal fold, the sig-
moid meso-colon.

The rectiun^^ extends from the left sacro-iliac articulation to
the anus, is from six to eight inches long, curves slightly to
the right and then adapts itself to the sacral curve, and at the
apex of the prostate gland inclines backward to the anus; it is
non-.?acculated, but just above the anus presents a dilatation,
or ampulla ; it is only covered with peritoneum to its second
portion, forming a meso-rectuni ; it leaves it wholly, to be re-
flected upon the bladder or uterus, three and one-half inches

276 ESSENTIALS OF HUMAN ANATOMY.

(8 cm.) from the anal orifice. The rectum has three parts :
the Jint continues from tlie sigmoid to the tliird sacral vertebra ;
the second from there to the apex of the prostate gland ; the
f/n'rd poifum is the <iu(d canal ^ one inch long.

The appendices epiploicrX are little peritoneal pouches filled
with fat placed along the colon and upper part of the rectum.

What guards the anal orifice?

The sphincter aui, a voluntary muscle, and the internal
sphincter, the continuation of the circular muscular coat.

What are the folds of Houston ?

Three semilunar folds of mucous membrane, one on the
right side of the rectum or third sphincter ; two more are on
the left side, one above the level of the right fold, and one below.

Name the glands of the large intestine.
Crypts of Lieberk'dhn and sulitart/ gkuids.

Give the blood- and nerve -supply of the large intestine
and rectum.

The arteries are branches of the superior and inferior mesen-
teric^ the middle hemorrhoidal from the internal iliac, and the
inferior hemorrhoidal from the internal pudic, and a few more
from the sciatic.

The veins empty into the portal system, except the inferior
hemorrhoidal.

The nerves come from the sympathetic plexuses around the
mesenteric arteries, and, in the case of the rectum, the fourth
anterior sacral nerve and internal pudic supply the sphincter
ani muscle.

The Liver.

Describe it (Figs. 117 and 119).

It occupies the right hypochondrium extending across the
epigastrium into the left hypochondrium to the mammary line.
It is the largest gland in the body, weighing from three to four
pounds; its transverse diameter is eleven inches (28 cm.), its
antero-posterior eight (20 cm.), its greatest vertical five to
seven inches. Covered by peritoneum, except at the attach-
ments of the ligaments, it possesses sl fibrous coat, covering the
whole organ continuous with the capsule of Glisson at the trans-

THE LIVER.

277

verse fissure ; there are three surfaces, an anterior border, right
and left ends, five fissures, five lobes, five ligaments, and five
sets of vessels.

Superior surface is convex, smooth, lying in contact with the
diaphragm above, and below with a small portion of the ab-
dominal wall ; it is divided into two unequal lobes by a peri-
toneal fold, the suspensory, hroad, or falciform ligament; the

Inferior surface is concave, is in relation with the stomach.

Gastric
surfiice / /■
Tuber pupil- l^r

Inre
Tuber omen- J
tcUe

Xon-periioneal

surface
Im}>. snpra-ren.
(non-perit.)

Imp. supra -ren.
Tiiipressio renalls
Imp. duodenalis

Impressio celica

Impressio pylorica
Fig. 117— Posterior and inferior surfaces of the liver.

duodenum, hepatic flexure of the colon, right kidney, and su-
prarenal capsule, and is divided by the left longitudinal fssure^,^,
into a right and a left lobe.

The posterior surface^;'' is rounded and grooved, presents a
margin of the left lobe, a groove for the esophagus, the liga-
mentum venosum in the fissure of the ductus venosus^ the
Spigelian lobe, a fossa for the vena cava, a small non-peritoneal
surface for part of the right suprarenal capsule, and a large one
for the diaphragm.

Anterior border^ is thin, sharp, and deeply notched at the
site of the round ligament and of the gall-bladder at the ninth
costal cartilage ; it correspctnds usually with the margins of the
ribs in males, projecting a little lower in women and children.

Describe the ligaments.

Tlicy are five in number (really ten), four being composed
of folds of the peritoneum ; the fifth is the obliterated umbilical
vein ; the

278 ESSENTIALS OF HUMAN ANATOMY.

Sufipensory or broad Ugament (falciform) is a falciform an-
tero-posterior peritoneal fold, with its apex backward, attached
to the liver from the notch on the anterior border to the coro-
nary ligament — its anterior free edge enveloping the round liga-
ment— and to the diaplivagm and sheath of the right rectus
muscle as low as the umbilicus ; the

Coronary Ujomeuts consist of two layers reflected from the
diaphragm on the upper and lower margins of the posterior
surface of the organ, between which firm areolar tissue binds
the liver to the diaphragm ; the

Lateral ligaments^ right and left triangular^ are prolongations
on each side of the two layers of the coronary, which unite
and extend from the diaphragm to the adjacent posterior sur-
face of the liver.

Round ligament^ a fibrous cord, ascends from the umbilicus
in the anterior free maro;in of the broad liirament to the lono-i-
tudinal fissure, traceable back to the vena cava ; the posterior
portion is the remains of the ductus venosus, the anterior of
the umbilical vein.

Describe the fissures.

They are five in number, dividing the posterior and inferior
surfaces of the organ into five lobes ; they resemble the letter
H.

Left longifiidlnal Jissnre^^^ extends from the notch on the
anterior border, inferiorly and posteriorly to the posterior mar-
gin of the superior surface, separating the right and left lobes,
and is joined by the f ran sverse fissure ^'^ ; the anterior portion of
the fissure is called the nmhilical fissure from lodging the fetal
umbilical vein ; posterior portion, the y7S.s?<re of the ductus veno-
sus, lodging the obliterated fetal vessel ; either part is often
partially bridged over by the pons hepatis.

Transverse fissure^'^, porta, hepatis, or hihmi, is two inches long
and one-half inch wide, passing transversely across the under
surface of the right lobe between the two longitudinal fissures ;
here enter the portal vein, hepatic artery, and nerves, and the
bile-ducts and lymphatics emerge.

Fissure of the gall-bladder^*, fossa vesicalis, lies parallel and
to the right of the umbilical fissure reaching back nearly to
the transverse fissure.

Fossa for the vena cava is short and deep, sometimes con-

THE LIVER. 279

verted into a canal ; it separates the Spigelian from the right
lobe, and is separated from the transverse fissure by the cau-
date lobe ; the hepatic veins here empty into the vena cava.
These two fossae form an interrupted right longitudinal fissure.

Describe the lobes of the liver.

They are five in number ; the

Right lobe^, the largest, of a quadrilateral form, its surfaces
being superior, inferior, and posterior, marked by three fissures,
viz. transverse, one for the gall-bladder, and one for the inferior
cava, which separate three more lobes ; four impressions are
seen on the under surface ; posteriorly, the renal and supra-
renal; anteriorly, one for the colon; internally, one for the
duodenum.

Left lohe}, smaller and flattened, resting by its inferior con-
cave surface on the stomach, presenting a prominence, the tuher
omejitale.

Lohus quadrafus^ is marked oif from the under surface of the
right lobe by the transverse fissure behind, by that for the
gall-bladder on the right, and anterior part of the longitudinal
fissure on the left.

Lohus Spigelii^ projects from the posterior surface of the
right lobe, bounded in the front by the transverse fissure, on
the right by that for the vena cava, and on the left by the
fissure of the ductus venosus.

Lohus caiidatus^ is a small elevation running obliquely out-
ward from the base of the lobus Spigelii to the under surface
of the right lobe ; it intervenes between the right end of the
transverse fissure and the commencement of that for the vena
cava.

Describe the vessels of the liver.

They number five, hepatic artery, portal vein, hepatic veins,
hepatic duct, and the lymphatics ; the first three are enveloped
in loose an^olar tissue called the capsule o/ 6V/.s-.so», which ac-
companies the vessels through the p)ort<d canals in the interior
of the organ.

rortal rriii^^ (vein of the gate), about four inches long, col-
lects blood from the viscera of digestion ; it is formed by the
junction of the superior mesenteric and splenic veins, the lat-
ter receiving the bhxxl returned ])y the inferior mesenteric

280

ESSENTIALS OF HUMAN ANATOMY.

vein, while the cystic and two gastric veins empty into the
portal vein itself. Entering the transverse fissure it divides
into branches for the right and the left lobes, which receive the
vaginal and capsular veins, and subdividing form the interlobu-
lar veins^ (^'ig- 118),w^hich send branches to the interior of

^:^/W ijW

Fig. 118.— Cross-section of a lobule of the liver (Leidy).

each lobule, forming a plexus converging to empty into the
central intralohular vein'' running at right angles to other ves-
sels ; the intralobular vein empties into a auhlohidar vein, a
radicle of the hepatic vein ; the

Uejyatic veins commence in sublobular veins as just described,

THE LIVER. 281

which unite to form three large and several smaller branches
terminating in the inferior vena cava in the fissure for that
vessel.

Hepatic artery^'' springs from the celiac axis, enters the
transverse fissure, and divides into branches which ramify in
the capsule of Glisson ; vugiiud, supplying nutriment to the
vessels, ducts, etc. ; capmlar to terminate in the external fibrous
coat ; inferhhular pass to the interlobular plexus on the outer
surface of each lobule; doubtful if any branches enter the
capillary network between the cells.

Hepatic duct^^ is formed by the union of two bile-ducts of
nearly equal size which emerge from the transverse fissure, one
from the right, the other from the left lobe ; it passes down-
ward to the right for one to two inches, to be joined by the
cystic duct from the gall-bladder, forming the ductus communis
choledochus.

Lymphatics consist of a superficial or subperitoneal and a deep
or interlobular set accompanying the blood-vessels, emerging
with the hepatic veins and at the portal fissure.

Whence do the nerves of the liver come ?

From the solar plexus of the sympathetic and from the left
pneumogastric ; the phrenics supply part of the external
surface.

Describe the liver structure.

It is composed of numerous lobules from one-twentieth to
one-tenth of an inch in diameter, of irregular form in the human
liver, polygonal in pigs, their bases clustered round the sub-
lobular vein, to which each is connected by its intralobular
vein ; the lobules are bound together by loose areolar tissue ;
each lobule consists of nucleated hepatic ce/ls, spheroidal or
many-sided, with nucleoli, measuring from one two-thousandth
to one one-thousandth of an inch, containing granular yellow
coloring-matter and globules, which cells lie in the meshes of
the dense capillary network occupying its interior; spaces be-
tween the cells form the interceUn/ar Miliary passages", bile-
canaliculi, the radicles of the bile-ducts.

What is the capsule of Glisson ?

The areolar tissue which surrounds the three vessels in the
right free margin of the lesser omentum, entering the trans-

282 ESSENTIALS OF HUMAN ANATOMY.

verse fissure, forms poit<d canals for the same vessels to their
ultimate ramifications, and is continuous with the fibrous coat
of the organ. In a section of liver-tissue the portal may be
distinguished from the hepatic veins by the fact that the
former are collapsed, being surrounded by the capsule of Glis-
son, while the hepatic are held open, being closely connected
with the liver-substance.

Describe the gall-bladder^*.

It is a pear-shaped, fibro-muscular receptacle for the bile ; its
fundus and under surface of the body and neck are covered by
peritoneum, while its interior is lined with a cylindrical-celled,
epithelial-coated mucous membrane, presenting a honeycombed
appearance from the confluence of numerous minute rugae ; its
length is from three to four inches, its capacity from eight to
twelve fluidrachms, and it lies in a fossa on the under surface
of the liver, its fniulus — most dilated portion — projecting
slightly beyond the anterior border, touching the abdominal
wall just below the ninth costal cartilage ; the narrow neck
curves upon itself like an italic _/', to terminate in the c?/sh'c
f7?/c^, which is one to three inches long, and is lined by mucous
membrane so disposed in a series of creseentic folds as to
present the appearance of a spiral valve^ which is called the
valve of Heister ; the cystic duct joins the hepatic duct to
form the common bile-duct.

Describe the ductus communis choledochiis ^^ (Ficr. ]]7).

It is about three inches long, three-sixteenths of an inch in
diameter, and is formed by the junction of the hepatic and
cystic ducts ; it opens usually by a common orifice with the
pancreatic duct, from a small sac of mucous membrane and
papilla Vateri a little below the middle of the inner side of the
descending portion of the duodenum; its walls are composed
of fibrous with a little muscular tissue, its mucous membrane
is covered with columnar epithelium, and it runs between the
layers of the gastro-hepatic omentum.

What are the relations of the liver ?

Aufcro-siiperiorlf/, diaphragm, right and left lyngs. peri-
cardium and heart, anterior abdominal wall, six or seven right
lower ribs ; iiiferiorly^ right kidney and capsule, hepatic flexure
of colon, duodenum, gall-bladder and cystic duct, vessels at the

THE PANCREAS.

283

transverse fissure, stomach ; posteriorly, diaphragm and crura,
tenth and eleventh thoracic vertebrae, esophagus, aorta, inferior
vena cava, thoracic duct.

The Pancreas.

Describe the pancreas'* (Fig. 119).

It is a compound racemose gland, of pyramidal shape, about
six inches long, one and a half inches wide, and one inch thick.

Fio. 119.— View of duodenum and pancreas.

is indicated by dotted lines (Testut) . ^.quadrate lobe; B, ri
right and left suprarenal capsules; A left kidney ; A, pancri

The part of stomach removed
[' lobe; B, right kidney; (\( ' ,

reas; /', U])per i>art

17, ve'na'cava inferior; IK, inferior mesenteric vessels; ]".♦, spermatic vessels.

lying behind the stomach and in front of the second lumbar
vertebra. It is compo.sed of lobules connected by areolar
tissue, each lobule consisting of an ultimate branch of the

284 ESSENTIALS OF HUMAN ANATOMY.

duct lined with columnar epithelium, terminating in cecal
pouches or acini, also lined with cylindrical epithelium, outside
of which is a line capillary network ; the

Pancreatic duct (canal of WirsiiJi(/) extends the whole length
of the gland and opens into the descending part of the duode-
num, to the inner side, with the common bile-duct; the

Head, or n'(/ht extremity, is embraced by the concavity of the
duodenum, the common bile-duct lying behind, the superior
and inferior pancreatico-duodenal arteries in front. A part of
the head may curve behind the superior mesenteric vessels and
be partially detached, the lesser pciucreas. The ta'di or left
extremity^ reaches the spleen either across the upper end of
the left kidney and capsule or across the center of the kidney,
touching same part of the spleen in each case. The neck is one
inch long, constricted between the first and last portions of the
duodenum. The hady is triangular on section, with its apex
forward, placed at the point of separation of the two layers of
the transverse mesocolon ; it presents three surfaces, anterior,
2)oster{or, and a narrow inferior^ and three borders, superior,
anterior, and inferior. Relations : above, first part of the
duodenum, celiac axis, solar plexus, splenic and hepatic arte-
ries, left lobe of the liver; in front, lesser sac, stomach, pan-
creatico-duodenal arteries, transverse colon, upper layer of the
transverse mesocolon; heloic, duodenum, -jejunum, transverse
colon, lower la3'er of the transverse mesocolon, superior
mesenteric vessels, inferior mesenteric vein, mesentery ;
behind, second lumbar vertebra, pancreatic and common bile-
ducts, aorta, vena cava, origin of the thoracic duct, vena
portae, crura of the diaphragm, solar plexus, superior mesen-
teric artery, right and left renal vessels, left kidney and cap-
sule ; spleen at the left end, curve of the duodenum at the
right end.

The arteries are derived from the hepatic, splenic, and supe-
rior mesenteric ; I'ejns are of the same names and empty into
the portal system ; nerves come from the solar plexus. In
structure the pancreas resembles the parotid gland.

The Ductless Glands.

What are the ductless glands ?

The spleen, suprarenal capsules, thyroid and thymus glands,
bodies whose functions are uncertain and which have no ducts.

THE SPLEEN. 285

The spleen and suprarenal capsules lie in the abdominal
cavity, but the glands Avill be for convenience described after
the spleen.

The Spleen (Figs. 116 and 119).

Describe it.

It is a soft, brittle, very vascular, oblong, flattened organ
embracing the fundus of the stomach, to which it is attached
by the gastro-splenic omentum, which completely invests the
spleen, except at the hilum and where the suspensory liga-
ment is attached ; the organ lies deeply in the left hypochon-
drium, and has three surfaces, ^jA/'e«/c, Lki.s(iI, and iiifcnial, and
three borders.

Outer phrenic surface is convex, smooth, lying in contact
with the diaphragm, Avhicli separates it from the ninth, tenth,
and eleventh ribs ; the

Inner surface is concave, presents the hilnni and intermediate
border separating a posterior renal surface^i'rom an anterior
gastric surface.

Hilum is a vertical fissure pierced by blood-vessels, lym-
phatics, and nerves.

Basal surface bounds the lower end of the spleen, touches
the pancreas, rests on the splenic flexure of the colon and
on the phreno-colic ligament.

Anterior border is often notched ; the j^^sterior border is
rounded and in relation with the left kidney ; the

Suspensory ligament.^ a peritoneal fold, connects it with the
under surface of the diaphragm.

Tlic sustentaculum lienis (supporter of the spleen) is the
phreno-colic ligrrment, which passes from the diaphragm oppo-
site the anterior ends of the tenth and eleventh ribs to the
splenic flexure of the colon.

Jldations: externallg and <djove, peritoneum and diaphragm,
ninth, tenth, and eleventh ribs, costo-phrenic sinus, left lung
and pleura, left lobe of the liver (at birth), muscles of the
back ; internallf/, stomach, left kidney and capsule, tail of
the pancreas ; inferiorly^ tail of the pancreas sometimes, splenic
flexure of the colon, phreno-colic ligament.

Fibro-clastic voat^ l)en(!ath the serous, wliich intimately ad-
heres to it, forms the franuiwork of tlu^ spleen, jiassing inward
at the hilum with the vessels as sheaths, from which, and the

286 ESSENTIALS OF HUMAN ANATOMY.

inner surface of" the capsule, numerous bands or trahecnlbe pass,
uniting to form numerous small spaces or uitolyt filled with
the splenic pulp.

Describe the spleen-pulp and Malpighian bodies.

It is of a dark reddisli-bruwn culur, and under the microscope
is seen to consist of a network of branched connective-tissue
cells, containing pigment-granules (broken-down blood-cor-
puscles), granular matter, nucleated cells, free nuclei, and red
blood-cells in all stages of disintegration ; the

Splenic artery'"^ (l^'ig- H^) is large, tortuous, and divides at
the hilum into five or six branches wdiich do not anastomose to
any extent, each branch breaking up again and again into
smaller ones, until they terminate in bundles of straight ves-
sels which open into the interstices of the reticulum formed
by the branched connective-tissue cells.

The Molpiglikui bodies are small, rounded, expanded masses
of the lymphoid tissue of the external coat of the small splenic
arteries, from one one-hundredth to one twenty-fifth of an inch
in diameter, usually surrounding the vessel, but sometimes
projecting from one side ; they are composed of a delicate
reticulum packed with lymph-corpuscles and pervaded by
capillaries ; the

Splenic vein, arises from the lacunar spaces in the pulp, has
free anastomoses, and empties into the portal vein ; the

Kerves are derived from the right pneumogastric nerve, the
right and left semilunar ganglia, the solar plexus, and attend
the arteries.

Lynipliatics form two sets, trabecular and perivascular.

The Thyroid Gland.

Describe it.

It con.sists of two lateral lobes situated at the sides of the
upper portion of the trachea, connected at about their lower
thirds by a narrow transverse portion, the isthntus. which is
occasionally absent. A third lobe, the pyramid, sometimes
springs from the left upper side of the isthmus, or the left
lobe, and extends to the hyoid bone ; it is at times detached ;
occasionally a slender muscular band — the levator glandidse
tltyroidesf: — extends from the hyoid bone to the isthmus or the
pyramid. Structurally, the gland consists of a connective

THE THYMUS GLAND. 287

tissue capsule, sending in septa subdividing the organ into
lobes, each of which is formed of numerous closed vesicles
filled with a viscid yellowish fluid embedded in connective
tissue containing a dense vascular plexus surrounding the
vesicles.

Two jmnifJiT/rold ffkuids are desGYihed as constant in man and
other mammals, each lying near a lateral lobe of the thyroid.

What arteries supply this gland ?

The superior and the infrrior thyroid branches respectively
of the external carotid and the thyroid axis, and at times the
thijroidea ima, springing either from the innominate artery or
the aortic arch itself, to pass up on the front of the trachea.
These vessels are remarkable for their size and frequent
anastomoses.

Describe the veins of the thyroid gland.

They form a plexus on the surface of the gland, whence
arise the

Superior- thyroid vein, ) ^ ^ . • ^ ^i • ^ i • i
ar- 7 77 ^7-7 • ' V r-imptying into the internal lugular vein.
Mid die thyroid veni, \ i J n j o

Inferior thyroid vein opening into the innominate vein.

Name the nerves.

Branches of the middle and inferior cervical ganglia.

The Thymus Gland.

Describe it.

It is a temporary organ of unknown function, reaching its
full development at the end of the second year, after which it
gradually atrophies, having nearly disappeared at puberty.
When fully developed it extends from the fourth costal carti-
lage to the lower border o{' the thyroid gland, consisting of two
lateral lobes in close contact along the middle line, while some-
times an intermediate lobe exists ; the sternum and origins of
the sterno-hyoid and sterno-thyroid muscles cover it, as it lies
in the neck behind these muscles upon the front and sides of
the trachea; it rests, in the mediastinum, upon the pericar-
dium, the thoracic fascia separating it froni the aortic arch and
great vessels. Its dimensions arc : length, two inches; breadth,
one and a half inches; thickness, one-quarter of an inch; at
birth it weighs about half an ounce.

288 ESSENTIALS OF HUMAN ANATOMY.

Describe its structure.

It is formed of numerous lobules bound together by delicate
areolar tissue, all being ineloscd by a fibrous capsule ; the
lobules are composed of a cortiad lymphoid tissue, and a
mrdnlldfij portion containing a few lymphoid cells, but toward
the center granular cells and concentric corpuscles exist. Each
follicle is surrounded with a capillary plexus.

Describe the arterial and nerve-supply.

The <iit( rif'S are derived from the internal mammary, supe-
rior and inferior thyroid, subclavian and carotid.

The veins empty into the thyroids and left innominate.

The li/mphatics are large and arise from an interlobular
plexus in the substance of the gland, and are said to empty
into the internal jugular veins.

The nerccs are very minute, coming from the pneumogastric
and sympathetic ; the descendens cervicalis and phrenic prob-
ably reach the capsule.

The Suprarenal Capsules.

What are they?

Two triangular or semilunar flattened bodies, situated behind
the peritoneum, immediately above and in front of the upper
part of each kidney ; the right one is triangular, the left, cres-
centic and larger. They consist of a thin, closely adherent
Jibrous capsule, which sends numerous communicating partitions
inward, a corf real strid a medullar?/ portion ; the former contains
columns of finely granular polyhedral cells, with channels be-
tween them and the fibrous portions, believed to be lymph-
sinuses ; the medullar?/ p)ortioii is formed of stout connective-
tissue bundles between which lie coarsely granular columnar
and branched cells, which have been thought to communicate
with a very fine nerve-plexus found in the medulla.

With what parts do these organs lie in contact?

The anterior surface of the riglif capsule touches the under
and back surfaces of the right lobe of the liver, is partly
covered by the inferior vena cava, and at the internal inferior
angle is crossed by the hepatic curve of the duodenum ; poste-
riori?/ it lies on the diaphragm.

The left capsule has iii /ront the peritoneum of the lesser

THE ABDOMINAL CAVITY. 289

sac, stomach, spleen, upper border of the pancreas, splenic
artery ; poateriorli/ is the left crus of the diaphragm. They are
related by their inner margins to the great splanchnic nerves
and semilunar ganglia, on the right side touching the inferior
vena cava, and on the left side the left crus of the diaphragm.

Name its vessels and nerves.

The arteries are from three sources : the suprarenal and
branches of the inferior phrenic and renal arteries forming a
dense capillary network in the interior ; the

Venous capillaries return blood from the medullary venous
plexus by a single suprarenal vein which empties into the in-
ferior cava on the right side, and on the left into the renal vein.

Nerves are very numerous, chiefly distributed to the medulla,
and are derived from the solar and renal plexuses and the
phrenic and pneumogastric nerves, having developed upon
them numerous small ganglia, hence the opinion held by some
that these bodies belong to the sympathetic nervous system.

The Abdominal Cavity.

What is the abdomen ?

An ovoidal cavity, limited above by the diaphragm, below by
the brim of the true pelvis ; in front and at the sides by the
lower ribs, abdominal and iliac muscles ; behind, by the verte-
bral column, psoas, and quadratus lumborum muscles; it is
lined with peritoneum — a serous membrane — which is reflected
to form partial or complete investments for the contained
organs or viscera.

Name the abdominal viscera.

Stomach, Suprarenal capsules,

Intestines, Aorta,

Liver, Inferior vena cava,

Gall-bladder, Thoracic duct.

Spleen, Ileceptaculum chyh,

Pancreas, Bladder if distended.

Kidneys,' Uterus if enlarged.

Describe the openings in its walls.

They are the umlnliad for the fetal umbilical vessels, ob-
literated after birth, leaving a depression, the innhihcusj
openiufj for the inferior vena' cava in the diaphragm; aortic

19

290 ESSENTIALS OF HUMAN ANATOMY.

opening^ behind the diaphragm between the crura, for the
aorta, vena azygos major, thoracic duct, and sometimes the
left sympathetic nerve ; esopluigml opening in the diaphragm
for the esophagus and pneumogastric nerves ; internal abdomi-
nal ring, on each side, for the spermatic cord in the male,
round ligament in the female ; lacuna vascularis, on each side
below Poupart's ligament for the transmission of the femoral
vessels and crural branch of the genito-crural nerve, showing
internally the femoral or crural ring, the site of the femoral
hernia.

Into what regions is the abdomen artificially divided?

Into nine, by two imaginary parallel lines encircling the
body on a level with the ninth costal cartilages and summits of
the iliac crests, and two other parallel lines drawn from the
cartilage of the eighth rib on each side to the center of Pou-
part's ligament.

Quain takes as the upper horizontal line, infracostal, between
the lowest points of the thoracic border, usually the tenth
costal cartilages ; the inferior horizontal line, hi-iliac, unites
the most prominent (not highest) points of the iliac crests ;
this line cuts the fifth lumbar vertebra and is one and one-
quarter inches below the summits of the crests ; vertical lines
are mid-Poupart. Morris advises the same line above and the
interspinous line below, connecting the anterior superior spinous
processes of the ilia, also the vertical mid-Poupart lines.
Joessel's horizontal lines are infracostal and interspinous;
vertical, ascend to the upper horizontal line from the ilio-
pectineal eminences (Fig. 120). This marks ofi' three hori-
zontal zones, epigastric, mesogastric, and hypogastric.

The right lateral regions are, from above downward (see
cut), the

Right hypochondriac, which contains the right lobe of the
liver, gall-bladder, hepatic flexure of the colon, and upper part
of the right kidney.

Right lumbar, contains the ascending colon, lower part of the
right kidney, and some coils of the small intestine (ileum).

Right inguinal (^iliac), contains the cecum, often the appen-
dix vermiformis, and end of the ileum.

The median regions are :

Epigastric^ contains part of the right lobe of the liver, greater

THE ABDOMINAL CAVITY.

291

part of the left lobe, part of the gall-bladder, stomach, middle
and pyloric portions, both orifices, first two parts of the duo-
denum, duodeno-jejunal junction, pancreas, except the tail,
upper part of the spleen, part of the kidneys, suprarenal cap-
sules.

Umhilical, contains the transverse colon, part of the great
omentum and mesentery, transverse portion of the duodenum,

Fig. 120.— Regions of the abdominal cavity, anterior view (after Joessel).

and some coils of the jejunum and ileum, part of both kidneys
with ureters, and the receptaculum chyli.

IfypofjaHtrlc^ contains coils of the small intestine, the bladder
in children, or when distended in adults, ureters, the uterus
during the latter months of pregnancy, often the cecum,

292

ESSENTIALS OF HUMAN ANATOMY.

appendix vermiformis. sigmoid flexure of the colon, and the
upper part of the rectum.

The left lateral regions from above downward are :

Left liypocliondrlac^ contains the fundus of the stomach,
greater part of the spleen, tail of the pancreas, splenic flexure
of the colon, upper part of the left kidney, and part of the
left lobe of the liver.

Left lumbar, contains the descending colon, part of the omen-
tum, sigmoid flexure, lower part of the left kidney, and some
coils of the jejunum.

Left inguinal (iliac), contains the sigmoid flexure of the
colon and convolutions of the jejunum and ileum.

The Peritoneum.

Describe it (Fig. 121).

A serous membrane, forming a closed sac (in the 7nale), the
layer covering the walls being called the parietal, and that

reflected over the viscera the
^ .„ {v=j(. viscend \2iyeY ; it is coated with

a layer of flattened endothe-
lium, its attached surface being
connected with the subjacent
parts by the subperitoneal areo-
lar tissue or fascia.

Does the peritoneum always
form a closed sac?

No ; in the female the Fal-
lopian tubes open into its cavity.

How is the peritoneum divided
for convenience of de-
scription ?

Into the greater sac^^, or that
covering the upper anterior por-
tion of die liver^, the stomach^
in front and above, descending

FIG. i2i.-Diagrain to illustrate over the ileum forming the an-
the reflections of the peritoneum m terior layer of the great omen-
thefen^aiebody (Leidy). ^^^^^^,5^ t],^ under layer of the

mesocolon"'^", the mesentery'', and reflections^^ upon and be-

THE PERITONEUM. 293

tween the rectum ^\ the uterus in the female'", and the bladder'^,
then lining the antero-lateral abdominal walls to reach, from
the under surface of the diaphragm ^^, the upper surface of the
liver, the starting-point of this description (see Fig. 121).

The lesser cavity, or cavity of the great omeiifam^^^ starting
from the diaphragm behind, passes over the Spigelian lobe of
the liver '^, then covers the back and under surface of the stom-
ach^, forms the inner layer of the great omentum''', passes
over the colon'' completing the mesocolon ■^°, and thence passes
over the pancreas'*' and great vessels to line the posterior ab-
dominal wall, reaching the point started from ; the two cavities
communicate throuo'h the foramen of Winslow.

Describe the foramen of Winslow '^

It is the orifice of communication between the greater and the
lesser sacs, admitting two fingers ; bounded above by the cau-
date lobe of the liver, below by the first part of the duodenum
and hepatic artery, in front by the right free border of the
lesser omentum, containing the hepatic artery, common bile-
duct, and vena porti^ ; behind by the inferior vena cava.

What are the omenta?

They are folds of peritoneum connecting the stomach with
the other viscera, four in number, viz. the

Gasfro-hepatiCy or lesser omentum^^^ extending between the
transverse fissure of the liver, lesser curvature of the stomach,
and beginning of the duodenum, consisting of two layers, the
anterior belonging to the greater, the posterior to the lesser
sac, which enfold at the right free border of the omentum,
the hepatic artery^ common hile-dnct^ portal vein, lymphatics,
and hepatic nerve-plexus ; this border is called the hepato-
duodenal ligament.

The great omentum^'* is formed of four layers, two descend-
ing, one from the anterior, the other from the posterior wall
of the stomach, and uniting below to pass as low as the pelvis,
when they ascend to the transverse colon, separate and em-
brace this part of the bowel, and pass to the pancreas as the
transverse mesocolon. At about the age of two years the
two anterior layers of the great omentum become adherent
to the transverse colon ; the part between the stomach and
colon is then called the gasfro-colic omentum.

294 ESSENTIALS OF HUMAN ANATOMY.

Gasfro-splcuic omentum is a double fold connecting the spleen
with the stomach, contains the vasa brevia of the splenic artery,
and is continuous below with the great omentum.

What are the mesenteries?

Double layers of peritoneum embracing various portions of
the intestinal tube connecting them to the vertebral column or
posterior abdominal walls ; between the folds run the vessels
of the part attached. They are called the

Mesentery'^^ ^ mesocecmn, mesocolon'^'^, mesorectunij mesogas-
trimn.

What are the ligaments?

Ligament is a term applied to the folds connecting the vis-
cera usually not belonging to the intestinal canal and abdom-
inal walls, such as

The gastro-2)hrenic to the cardia of the stomach from the
diaphragm.

The longitudinal^ two lateraP"^, and coronary ligaments of the
liver.

The vesical, five so-called false ligaments.

Two vesico-uterine'^^, two recto-'uterine'^'^ two hroad ligaments
of the uterus.

Suspensory ligament of the spleen connecting this organ with
the diaphragm ; also the supporting ligament or phreno-colic.

Mention the viscera wholly (M and partially (^) covered with
peritoneum, and those totally deficient (^) in such in-
vestment.

(1) The spleen, small intestine^, cecum, transverse colon\ sig-
moid flexure, ovaries, ufervs, stomach^ and liver^ practically,
duodenum (first part), rectum^^ (first part).

(2) Duodenum^ (descending Rectum (second part"),

and transverse), Vagina^'- (upper part),

Ascending colon, Bladder ^^ (posterior surface).

Descending colon,

(3) Rectum^^ (lower part), Pancreas^^,
Bladder ^^ (base, ante- Kidneys,

rior surface). Suprarenal capsules,

Vagina (lower and anterior portion).

THE LARYNX. 295

ORGANS OF VOICE AND RESPIRATION.

The Larynx.

What is the larynx^ (Fig. ]22)?

The voice-organ, formed of cartilages united by ligaments,
the segments enjoying movement upon one another, which is
effected by numerous muscles.

Mention the component cartilages.

There are nine, three being single and three in pairs :

Thyroid cart ilage^ ^ Two arytenoid cartilages'^^

Cricoid cartilage ^, Two cuneiform cartilages^

Epiglottis^ Two cornicnla laryngis.

Describe the thyroid (shield-like) cartilage.

It consists of two alst^^ or lamellae, united at an acute angle
in front, forming a vertical ridge, whose more prominent upper
portion is called the j30Wi7^?7i Adami^^ or Adam's apple; the

Inner surfaces of the alae are smooth, giving attachment in
front, at the receding angle formed by their junction, to the
epiglottis, true and false vocal cords, thyro-arytenoid and thyro-
epiglottidean muscles.

The outer surface affords attachment along an oblique ridge
to the sterno-thyroid and thyro-hyoid muscles, below and behind
to the inferior constrictor muscle.

The upper harder presents a deep, median notch\ and is
slightly concave on either side.

The lower harder is connected medianly with the cricoid car-
tilage by the crico-thyroid membrane, and on each side by the
cri co-thyroid muscle.

The posterior borders are thick, rounded, and terminate above
and below on each side in cornua^ the two superior'^ having
attached to their apices tlic lateral thyro-hyoid ligaments,
while the inferior* articulate internally by an oval facet with
the cricoid cartilage ; to this border are also attached the stylo-
pharyngoiis nrid palato-]>haryngeus muscles.

Describe the cricoid f ring-like) cartilage.

It is placed with its narrow portion'', annulus, in front and
the broad lamina'' behind, has on (nwh side two articular fleets,

296

ESSENTIALS OF HUMAN ANATOMY.

BpiglottiS

one on the upper margin behind for the arytenoid cartilage, one
externally near the lower margin for the inferior cornu of the
thyroid cartilage.

The upper harder gives attachment in front and at the sides

to the crico-thyroid mem-
brane ; at the sides to the
lateral crico-arytenoid
muscles and inferior con-
strictor of the pharynx.

The loicer horder is hori-
zontal and connected with
the first tracheal ring by a
fibrous membrane.

The posterior surface
presents a median vertical
ridge ^ the Jinea eminens,
for the attachment of the
longitudinal fibers of the
esophagus, and on each
side a fovea for the at-
tachment of the posterior
crico-arytenoid muscle.

Chr/rt
Cuneiform. /P y\

0 ^^ „^^ „

Jri/lenoicl. \\/9rMerLOid^iiS\ our/ace

Ceiwu6eu.i -yiyifnoi'd Cxrtiiafreij ^ase^
fiost/cus ft ^tztpra^'S „

Cricoid.

/4iti ctU.^etfcr
/4ruCeKOld Cart.

/4lfica/ Jacetfor
jkf. Coz-nu. of
Tft^rotd Cart,

Describe the two aryte-
noid (pitcher-like) car-
tilages ^

They are pyramidal in
form, and are placed on
the upper border of the
cricoid ; each has three
surfaces and three bor-
ders, a base, and an apex.
Posterior surface of each
is triangular and concave,
and affords attachment to
the arytenoideus muscle ;
Antero-external surface
is convex, presents the fossa triangularis^ and has attached the
thyro-arytenoid muscle and false vocal cord ;

Internal surfaces face each other, covered by mucous mem-
brane ;

Fig. 122.— The cartilages of the larj-nx ;
posterior view.

THE LARYNX. 297

Base presents a concave, smooth articular facet for the
cricoid cartilage and two prominent angles ;

External angle has attached to it the posterior and lateral
crico-arytenoid muscles; it is called the muscular procesa ;

Anterior angle, the vocal process, has attached to it the true
vocal cord ;

Apex curves backward and inward and articulates with a cor-
niculum laryngis.

Describe the cornicula laryngis^ (cartilages of Santorini).

They are two small conical cartilaginous nodules surmount-
ing the apices of the arytenoid cartilages, affording attachment
to the aryteno-epiglottic folds.

Describe the cuneiform cartilages^ (cartilages of Wrisberg).
They are elongated cartilages contained in the free borders
of the aryteno-epiglottic folds just in front of the cornicula.

Describe the epiglottis '^

It is a thin, leaf-shaped lamella of fihro-cartilage, attached
by its apex to the reentering angle of the thyroid cartilage
just below the median notch ; it lies at the base of the tongue,
in front of the upper opening of the larynx, and during deglu-
tition shuts like a lid over the laryngeal orifice. Its

Base is free, rounded, curving forward toward the base of
the tongue.

Apex is attached to the receding angle of the thyroid by
the tliyro-epi glottic ligament.

Anterior surface is covered with mucous membrane reflected
on to the sides and base of the tongue, forming three glosso-
epi glottic folds ; externally on each side maybe a pliaryngo-
epiglof tic fold; a median elastic structure connects this surface
with the posterior surface of the hyoid body, the hyo-epiglottic
ligament.

Posterior surface shuts down over the laryngeal opening
during deglutition ; it presents a prominence called the tubercle
or cushion.

Lateral margins give attachment to the aryteno-epiglottic
folds.

How are the ligaments of the larynx divided ?

Into extrinsic, or those connecting the tliyroid cartilage and

298 ESSENTIALS OF HUMAN ANATOMY.

epiglottis with the hyoid bone, and cricoid cartilage with the
trachea ; and intrinsic, those binding the various cartilages
together.

Name the extrinsic ligaments.

TInjro-lujoid mcmhrane, middle and tico lateral thyro-hyoid
ligaments, containing a small cartilaginous or bony nodule,
cartilago triticea ; thyro- and liyo-epi glottic ligaments, crico-
tracheal membrane.

Name the intrinsic ligaments.

The intrinsic articulations of the larynx are four : crico-tliy-
roid below, crico-arytenoid above, each possessing a ligamentous
capsule and synovial sac. The strengthening bands of the
crico-thyroid joint are the anterior, j^ostero-sujwrior, and postero-
inferior herato-cricoid ligaments. The strengthening band of
the crico-arytenoid joint is the posterior crico-arytenoid passing
from below, upward and outward. Other ligaments are the
two superior and two inferior thyro-arytenoid and crico-thyroid
membrane.

What are the vocal cords?

The superior or false vocal cords, on each side, are two folds
of mucous membrane enclosing the superior thyro-arytenoid
ligaments composed of elastic tissue, stretching between the
angle of the thyroid cartilage below the epiglottis and anterior
surfaces of the arytenoid cartilages; the lower margin forms
the upper free crescentic margin of the ventricle of the larynx.

The true or inferior vocal cords are two strong, yellow elas-
tic fibrous tissue bands, the inferior thyro-arytenoid ligaments,
covered by thin, tightly adherent mucous membrane, which
pass from the receding angle of the thyroid to the anterior
angles of the arytenoid cartilages, the upper border forming
the lower margin of the ventricle of the larynx, the lower con-
tinuous with the lateral portion of the crico-thyroid membrane
each has the thyro-arytenoid muscle lying parallel externally
these cords or membranes produce sound by their vibrations
the false cords do not, although they indirectly influence vocal-
ization.

What are the glottis and the rima glottidis?

The glottis is the narrow triangular interval between the true

THE LARYNX. 299

vocal cords in front, and between the arytenoids and the vocal
processes behind ; the rima is the boundary of the space.

Describe the ventricle of the larynx.

It consists of an oval depression or simm on each side, be-
tween the true and the false vocal cords leading upward, ex-
ternal to the superior cord, into a cecal pouch, the sacculus
laryngis^ or laryngeal pouch.

Describe the sacculus laryngis.

It is a slightly curved conical membranous sac, situated be-
tween the inner surface of the thyroid cartilage and false vocal
cord on each side ; internally lined with mucous membrane,
perforated by orifices of the ducts of sixty to seventy follicu-
lar glands lying in the submucous tissue ; it is strengthened
externally by a fibrous capsule continuous below with the su-
perior thyro-arytenoid ligament, and has its inner (laryngeal)
surface covered by the inferior aryteno-epiglottideus, and its
external by the tliyro-epiglottideus and thyro-arytenoid mus-
cles, which compress the sacculus ; the pouch is probably a
remnant, and the function is resonance. '

What kind of epithelium has the mucous membrane ?

Above the false vocal cords squamous epithelium is found,
except in front, where it is covered by ciliated columnar cells
as high as the middle of the epiglottis ; below the false cords
only ciliated columnar epithelium is found.

Describe the muscles of the larynx and epiglottis.

Crico-thyroideus - (Fig. 123): origin^ hnver border of the
thyroid and anterior border of the lower cornu ; insertion, tri-
angular into the antero-lateral surface of the cricoid cartilage ;
action, increases tension of the vocal cords by lifting the cricoid
cartilage upward ; nerve, superior laryngeal.

Crico-arytenoideus posticus : origin, lateral half of the poste-
rior surf;ic(; of the cric(jid ; insertion, outer angle of the base
of the arytenoid cartilage ; action, the two muscles by rotating
the arytenoid cartilages outward open the glottis and tighten
the cords; nerve, recurrent laryngeal.

Crico-arytenoideus lateralis: origin, upper border of the side
of the cricoid ; insertion, outer angle of Lhe base of the aryte-

300 ESSENTIALS OF HUMAN ANATOMY.

noid ; action^ by rotating the arytenoid inward it closes the
glottis ; verve, recurrent laryngeal.

Thyro-arytenoideus : cyrigin, lower half of the receding angle
of the thyroid and crico-thyroid membrane ; wsei-tion, by an
outer and an inuer port ion into the base, two angles, anterior sur-
face of the arytenoid, and into both vocal cords ; action, relaxes
the vocal cords and compresses the sacculus laryngis ; nerve,
as above.

Arytenoideus has a firinsverse and two oblique portions ; passes
from the back surface and outer border of one arytenoid to the
same part of the other cartilage ; action, approximates the ary-
tenoids closing the back of the glottis ; nerves, superior and
recurrent laryngeal.

Kerato-cricoideus, near the posterior crico-arytenoid : origin,
from the lower border of the cricoid cartilage ; insertion, inferior
cornu of the thvroid cartilage ; action, possiblv steadies one
cartilage upon the other; only occasionally found, and usually
on one side.

Triticeo-glossus : origin, cartilage of the same name in the
lateral thyro-hyoid ligament; insei't ion, tongue v^ith. the hj^o-
glossus muscle ; occurs on one or both sides ; action, unknown.

Describe the muscles of the epiglottis.

Thyro-epiglottideus : origin, inner surface of the thyroid carti-
lage ; insertion, ar3"teno-epiglottic fold, margin of the epiglottis,
outer surface of the sacculus laryngis ; this may be described
as a part of the thyro-arytenoid muscle; action, depresses the
epiglottis ; nerve, recurrent laryngeal.

Arjrteno-epiglottideus superior: origin, apex of the arytenoid
cartilage; insertion, aryteno-epiglottic fold; action, narrows
the upper laryngeal orifice ; nerve, recurrent laryngeal.

Aryteno-epiglottideus inferior: origin, arytenoid cartilage above
the superior vocal cord ; insertion, part of the epiglottis and
inner surface of the laryngeal pouch ; action, compresses the
sacculus laryngis ; nerve, recurrent laryngeal.

Mention the arteries and veins of the larynx.

The arteries are laryngeal branches of the superior and infe-
rior thyroids, and dorsalis linguae for the epiglottis.

The veins empty into the superior, middle, and inferior thy-
roids, and the lingual.

THE TRACHEA AND BRONCHI. 301

What nerves supply the larynx?

The superior^ and inferior or recurrent laryngeal^ branches of
the pneumogastrie, the former derived largely from the acces-
sory part of the spinal accessory and superior cardiac sympa-
thetic nerves.

Superior laryngeal is chiefly a nerve of sensation, supplying
the laryngeal mucous membrane and arytenoid muscles by its
internal laryngeal branch, after piercing the thyro-hyoid mem-
brane ; and the crico-thyroid muscle by its external laryngeal
branch ; the

Recurrent laryngeal is the motor nerve supplying all the lar-
yngeal muscles except the crico-thyroicl ; the right nerve de-
scends in the neck to pass from before backward under the
subclavian artery ; the left winds in the same direction under
the aortic arch, and both nerves ascend in the groove between
the trachea and esophagus to their distribution, giving off in
their course cardiac, esophageal, tracheal, and pharyngeal
branches, and anastomosing with the superior laryngeal
nerves.

The Trachea and Bronchi.

What is the trachea^ (Fig. 123)?

It is a membranous, cylindrical air-tube, flattened posteriorly,
of a transverse diameter of three-quarters to one inch (2 to 2^-
cm.), length, four and one-half inches (10 to 11 cm.), extend-
ing from the lower part of the larynx (corresponding to the
sixth cervical vertebra) to the disk between the fourth and
fifth thoracic vertebrae, where it bifurcates to form the right and
left bronchus; it is composed of sixteen to twenty imperfect
cartilaginous rings surrounding two-thirds of the cylinder, en-
closed in a double elastic fibrous membrane connecting the
rings with one another, while the space behind has, within the
membrane, a layer of longitudinal and another of transverse
unstriped muscular fibers, the transverse being called the tra-
cJiealia munch' ; the last ring, by a triangular hooked process
curving backward between the bronchi, forms two imperfect
rings on either side for the right and left bronchus ; the lining
mucous membraiK! contains much lyni})hoid tissue and elastic
fibers, and is covered by several layers of epithelium, the most
superficial is columnar ciliated; mucous glands Vio in the poste-
rior part of the fibrous layer.

302 ESSENTIALS OF HUMAN ANATOMY.

Give the relations of the trachea in the neck.

It is covered in front from above downward by
Anastomoses between the an- Posteriorly^ it lies upon the

terior jugular veins, Esophagus,

Isthmus of the thyroid gland. Laterally^ are
Inferior thyroid veins, The common carotid arteries'*,

Arteria thyroidea iraa, Lobes of the thyroid gland,

Cervical fascia, Inferior thyroid arteries,

Sterno-hyoid muscle, Recurrent laryngeal nerves.

Sterno-thyroid muscle.

Describe its relations in the thorax.

It is covered from before backward by the
Manubrium of the sternum, Sterno-hyoid muscle,
Remains of the thymus gland, Sterno-thyroid muscle,
Left innominate vein, Posteriorly^ lies the

Arch of the aorta. Esophagus,

Innominate artery, Laterally^ on each side, the

Left carotid artery ^^, Pneumogastric nerve and

Deep cardiac plexus, pleura.

What are the bronchi?

Two tubes, structurally like the trachea, extending from its
bifurcation into the lungs, dividing and subdiving to form the
bronchial tubes, in whose walls only scattered cartilaginous
plates exist until the diameter .2 mm. (y^-g- of an inch) is reached,
when they become wholly membranous, while the muscular coat
and the elastic fibrous coat then form a continuous circular layer
around the smallest tubes ; the mucous membrane is covered
with ciliated columnar epithelium ; the right bronchus is wider,
shorter, and more horizontal than the left ; it is one inch long
(2.4: cm.), diameter, 2.2 cm., has five or six rings ; the left
bronchus is smaller, more oblique, and longer, two inches long
(5.1 cm.), diameter, 2 cm., and has nine or ten rings.

Describe the relations of each bronchus.

The right begins opposite the fourth thoracic disk, enters the
lung opposite the fifth thoracic vertebra, lying behind the supe-
rior vena cava and right auricle of the heart, having the right
pulmonary artery at first below, then anterior to it, and the
vena azygos major arching over it from behind.

THE LUNGS. 303

The left bronchus^ commencing at the same point as the right,

passes in front of the esophagus, thoracic duct, and descending
aorta beneath the aortic arch, the left pulmonary artery lying
at first above, then in front of it to enter the lung opposite
the sixth thoracic vertebra.

The left bronchus is Ivj parte rial ; the right gives off the
eparterial branch, then each gives four ventral and four dorsal
branches ; the right has in addition an azygos branch. On the
right the eparterial bronchus goes to the upper lobe, the first
ventral to the middle lobe, the three lower ventral and all the
dorsal to the lower lobe. On the left side the hyparterial
bronchus, which is the first ventral, goes to the upper lobe ;
the other ventral and all the dorsal pass to the lower lobe.

What vessels and nerves supply the trachea and bronchi ?

The arteries are tracheal branches of the inferior thyroid
arteries and the bronchials from the aorta ; the

Veins empty into the thyroid plexus and bronchial veins.

Lympliaticii empty into the mediastinal glands.

Nerves are branches from the pneumogastric, recurrent
laryngeal, and sympathetic.

The Lungs.

Describe them (Fig. 123).

They are the two organs of respiration, occupying the greater
part of the thoracic cavity, separated by the heart and other
contents of the mediastinum, covered by the pleura?, of a
specific gravity of 0.34.5 to 0.746, the right weighing twenty-
two ounces, the left, twenty; in the ratio of 11 to 10. They
are pinkish-white at birth, but irregularly marked by slate-
colored patches as age advances from the deposit of carbona-
ceous matter in the lung-tissue (a condition called anthracosis) ;
they are divided into lobes, the right lung having three *, ^, *,
the left two^^; each lung has an apex, four surfaces, and two
borders.

Apex, extending into the root of the neck above the first rib,
about one to one and a half inches, where it is in relation with
the first and second part of the subclavian artery, separated
by pleura ; the

Bfme or phrenic surface is broad and concave, resting upon
the diaphragm, its thin margins extending lower down exter-
nally and behind than in front ; the

304

ESSENTIALS OF HUMAN ANATOMY.

External or costal surface is smooth, convex, miirked by the
interlobular fissures, and conforms to the shape of the thorax.

Inner or mediastinal surface is concave, and the left lung
presents a depression in front for the heart ; above and behind

Fig. 123— Anterior view of the larynx, trachea, lungs, and heart (Leidy).

the center each presents the hilum pulmonis, for the attach-
ment of the root of the lung ; the

Root"^^ consists of a bronchus, pulmonary and bronchial arte-
ries, pulmonary and bronchial veins and lymphatics, bronchial
glands, anterior and posterior pulmonary plexuses, all con-
nected by areolar tissue and enclosed by pleura ; in front of
each lies the phrenic nerve and anterior pulmonary plexus;
behind, the pneumogastric nerve and posterior pulmonary
plexus.

THE LUNGS.

305

In what order are these various structures arranged?

From before backward ;

Both lungs :

Pulmonary veins,
Pulmonary artery,
Bronchus, etc. )

From above downward ;

may be recalled by letters,

y. A, B.

Right luns: :

Bronchus, ^ , •

T-> I ^ f anterior

Pulmonary artery, V

Pulmonary veins, j

■

B

A I
V

posterior

Left lung :

Pulmonary artery,
Bronchus,
Pulmonary veins.

anterior

A

B
V

posterior

The j)osterior surface, often described as the border, is thick,
rounded, and fits into the sulcus pulmonalis on each side of the
vertebral column ; this surface on the left lung shows a groove
for the thoracic aorta, on the right lung a groove for the vena
azygos major. A low ridge lies parallel to and behind the
hiluin, and anterior to the groove ; this may be called the
jyosterior border (Joessel). The anterior border is sharp and
thin, overlaps the pericardium, and the left one presents a notch
or cardiac incisure. The inferior border is the sharp margin sur-
rounding the base of the lung, the greater part of which dips into
a pleural recess above the costal attachments of the diaphragm.

The left lung is divided by the left interlobular incisure or
fssure into two lobes ; this fissure passes from the upper and
back part of* the hilum, upward and backward through the
posterior surface, descends through the outer surface to the
inferior border, a thumb's breadth from the anterior border,
then passes up through the inner surface to the lower part of
the hilum. The linffual lobule is included between this and the
cardiac incisure. The right lung has two fissures and three
hjbes ; the rirfht interbtbubir incisure starts like the left one, is
more vertical and reaches the inferior )>order a hand's breadth
from the anterior border and passes up through the inner sur-
20

306

ESSENTIALS OF HUMAN ANATOMY.

face to the hilum ; this main fissure separates the lower lobe
from the upper and middle lobes. An additional fissure extends
from about the center of the above nearly horizontally forward

Upper lohr

Upper lobe

Sinus
phrenico-
co^tali

Sinus me-
'ladino-
costalis

J II ci sura

'iiterlob.

sinistra

Incis. car-

diaca
Siniisperi-
mrdiaco-
costdlis

Lob. lin-
giialis

L wer lobe

Line < inainmilUwis

Ltnea parasternalis

Linea sternal is

Liiiea mammillaris
Linea parastenudis

J'lace where pericardium is in direct con-
tact with sternum.

Fig. 124.— Relations of the lungs to the anterior chest-wall (after Joessel).

to the anterior border and thence on the inner surface to the
hilum.

Describe the structure of the lungs.

They have externally a serous coat, a subserous areolar tissue

THE LUNGS.

307

penetrating between the lobules ; lung-tissue is composed of
tlie pulmonary substance or parenchyma, which is formed of an
aggregation of lohules^ each composed of a terminal bronchial
tube with its air-cells, and ramifications of pulmonary and
bronchial vessels, lymphatics, and nerves, thus forming a lung
in miniature ; they are pyramidal and large upon the surface,
smaller and irregular in the interior ; the ahroli, or air-cells,
are small polyhedral alveolar recesses measuring about 0.25
mni. (-j-^o inch) in diameter. The bronchi divide bipinnately
into smaller and smaller bronchioles or lohulnr hronchial tuhes
which never anastomose; when the diameter is reduced to
about 0.2 mm. their walls and mucous membrane change, little
alveoli appear on a wall and finally cover it. At its end in a
lobule, it divides into parts named from the plan of a Roman
house (Fig. 125); first the atrium (entry) or alveolar jx^^^saye,

Fig P5 —Diagrammatic representation of the termination of a bronchial
tube in a group of infundibula: iJ, bronchial tube ; Zi?, bronchiole ; ^.atnum;
I, infundibulum ; C, alveoli.

from which arc given off blind pouches, infamUhnla, every-
where closely beset with air-cells ; they are separated from one
another by delicate membranous septa, between the layers of
which lies the plexus formed by the pulmonary artery, thus
exposing the blood to air on two surfaces; they are lined with
a layer of squamous epithelium.

What are the vessels and nerves of the lungs ?

They receive blood by the bronchial arteries for their own
nutrition, and venous blood by the pulmonary artery for aera-
tion— /. r. absorption of oxygen and emission of carbonic di-
oxid ; the vessels are:

308 ESSENTIALS OF HUMAN ANATOMY.

Bronchud arteries, branches of the aorta. Pnhnonari/ artery,
from the right side of the heart. The Itranchial vein empties
on the right side into the vena azygos major, on the left into
the superior intercostal vein. The pnlinoiiari/ veins, four in num-
ber, carry arterial blood to the left auricle.

Lymphatics, a superficial and a deep set, empty into the
bronchial glands ;

Nerves are derived from the anterior and posterior pulmo-
nary plexuses, formed chiefly by branches from the sympa-
thetic and pneumogastric nerves.

The Pleurae.

Describe the pleura.

They are two closed serous sacs, not communicating with
each other and wholly separated except anteriorly, leaving a
space called the mediastinum. The right sac is shorter and
wider than the left one.

The membrane reflected over the lungs to the roots is the
visceral layer, or pleura pidmonalis ; the part continuous with
this and lining the inner surface of the thorax is the parietal
layer, named, according to XoddXion, pleura costalis, Siho phrenic,
mediastinal, cervical, d^ndi pericardial pleura ; between the pari-
etal and visceral layers is the pleur(d cavity, which does not
exist unless made artificially or by disease, as the two layers
lie in contact. Descending vertically along the inner surface
of the lung from its root to the diaphragm is a double fold of
pleura, the broad pulmonary ligament {ligamentum latum pul-
monis^.

In certain regions two parietal portions of the pleura may
form a sharp angle or recess, into which the margin of the lung
may or may not enter ; it is a region between the extreme lung-
limit and extreme pleural limit, called pleural sinus, or com-
plemental space; sinus phrenico-costalis, or costo-phrenic, is the
angle where the costal and phrenic pleurae meet ; sinus niedias-
tino-phrenicus is antero-posterior on the upper surface of the
diaphragm, near the middle line, and most marked where the
pericardial pleura meets the phrenic; sinus mediastino-costalis
is more or less vertical, is anterior and behind the sternum ;
sinus pericardiaco-costalis is between the pulmonary and pleural
limits on the left side between the fourth and sixth costal car-
tilages, where the heart is not covered by the lung.

THE PLEURA. 309

Describe the mediastinum.

It is the median space between the two pleural sacs, extend-
ing from the sternum to the vertebral column, containing all
the thoracic viscera except the lungs.

It is divided into four parts, regarding the pericardium as a
center: iha middle medidsfu nun contains the pericardium and
contents ; the anterior is in front of it, posterior behind, and
superior above.

The superior mediastinum is bounded below by a plane
passing through the junction of the manubrium and gladiolus
to the lower border of the fourth thoracic vertebra; "in front
of it are the manubrium and origins of the sterno-hyoid and
sterno-thyroid muscles ; behind are the four upper thoracic
vertebrae and part of the longus colli muscles. It contains the
trachea, esophagus, thoracic duct, arch of the aorta, innomi-
nate artery, thoracic parts of the left common carotid and left
subclavian arteries, innominate vein, left superior intercostal
vein, upper half of the superior vena cava, phrenic, pneumo-
gastric, left recurrent, and cardiac nerves, lymphatic glands,
and remains of the thymus gland.

The anterior mediastimim^ placed obliquely, narrow above, is
bounded in front by the gladiolus, triangularis sterni muscle,
sometimes by the fifth, sixth, or seventh left costal cartilage;
behind is the pericardium. Its contents are areolar tissue,
lymphatic vessels, and two or three lymphatic glands.

The middle mediastiinrni contains the pericardium, heart,
ascending aorta, pulmonary artery, lower half of the superior
vena cava, arch of the vena azygos major, phrenic nerves and
attendant arteries, bifurcation of the trachea, roots of the
lungs, and the bronchial glands.

The posterior mediastimim lies between the pericardium,
roots of the lungs and diaphragm in front, and the thoracic
vertebral column behind, beginning at the fourth vertebra ;
it contains the thoracic aorta, esophagus, pneumogastric and
splanchnic nerves, azygos veins, some right intercostal arteries,
thoracic duct, and lymphatic glands.

Describe the topographical anatomy of the lungs and pleurae.
The surface of the chest is marked off by certain transverse
and vertical lines. Three levels are used for taking measure-
ments of circumferences of the chest-wall : (1) at level of the

310 ESSENTIALS OF HUMAN ANATOMY.

highest points of the axillae; (2) at level of the nipples; (3) at
level of the sterno-xiphoid articulation (Fig. 124). Vertical
lines are (1) the Unea mediana, ov mid-sternal line; (2) the
linea steriialis^ along each edge of the sternum ; (3) the linea
mammi/larix, or pdpiUftris, through the nipple; (4) the linea
parasternalis, midway between sternal and mammillary lines ;
(5) the Unea axWaris to the highest point of the axilla, also
the anterior and jioaferior axiU<iri/ lines from the anterior and
posterior folds respectively ; (6) the linea scapvlaris, drawn
through the inferior angle of the scapula ; (7) the mid-dorsal
or vertebral line, drawn through the spinous processes of the
vertebrae; (8) the linea sterno-costalis (costoclavicular line),
drawn from a sternoclavicular articulation to the tip of the
eleventh rib on the same side.

3Ieasurements of the Tliorax (Joessel).

Perimeters.
Male. Female.

At the level of the highest points of the axilla- . 89. o2 cm. 81 .90 cm.

At the level of the nip})les 86.64 cm. 81.00 cm.

At the level of the sterno-xiphoid articulation . 81.88 cm. 78.00 cm.

Diameters: transverse, through the eighth or ninth ribs, 28
cm. ; antero-posterior , at the base of the ensiform process, 20
cm. ; vertical along the posterior wall, 31.5 cm. ; vertical along
the anterior wall, 15.5 cm.

The internal sagittal diameter is 1 cm. more than half the
external, or 11 cm. ; the internal transverse diameter is \^ to
2 cm. less than the external.

Pleimd limits : anteriorly the right and the left pleural mar-
gins pass from the sterno-clavicular articulations and meet be-
hind the sternum at the junction of the manubrium and gla-
diolus ; from the second to the fourth or fifth cartilages they are
in contact or overlap ; here the left layer usually deviates, and
at the level of the sternal end of the fifth costal cartilage is 1.5
cm., at the sixth 2 cm., and at the seventh 3.5 cm., external
to the left margin of the sternum ; on the right side it descends
to the level of the sixth costal cartilage in the midline ;

At the sternal line the pleura on the right side crosses the
upper margin of the seventh costal cartilage ;

At the parasternal line it crosses the middle of the seventh
costal cartilage ;

THE PLEURA. 311

At the mammiUari/ line it crosses tlie lower margin of the
seventh costal cartilage ;

At the middxilhiry line it crosses the ninth rib ;

In the vertebral region it reaches the twelfth rib or the trans-
verse process of the first lumbar vertebra. The limit on the left
side may be a little lower than on the right, but clinically there
is no difference.

Surface form of the lungs : the anterior borders of the lungs
approach from the sterno-clavicular articulations, and almost
meet behind the sternum on a level with the second costal
cartilages ; thence they descend together to the level of the
fourth cartilages ; the right margin passes nearly straight
behind the sternum to the level of the sixth chondro-sternal
articulation. The lowest lung-limits on the right side are :

At the sternal line, upper margin of the sixth costal carti-
lage;

At i\\Q parasternal line, lower margin of the sixth costal car-
tilage ;

At the mammillary line, upper margin of the seventh rib ;

At the midaxillary line, lower margin of the seventh rib ;

At the scapular line, the limit crosses the ninth rib ;

In the vertehral region, it reaches the eleventh rib.

At the fourth costal cartilage the anterior margin of the left
hnig slopes outward under its lower edge, crosses behind the
fifth cartilage, and reaches a spot in the fifth space correspond-
ing to the apex of the heart ; the margin then curves inward,
but not to reach the sternal line again. This space uncovered
by the lung is the " area of superficial cardiac dulness."

The lower edge of the Ungual lobule touches the sixth costal
cartilage in the parasternal line and then the lowest lung-
limit runs, as on the right side, to the eleventh rib. The
height of the costo-phrenic sinus in quiet respiration is 2 cm.
ffour-fifths of an inch) at the sternal, parasternal, and mam-
millary lines, 6 cm. at the axillary, and 2.5 cm. in the vertebral
region.

The line of projection of the left intrrhthuhir incisure on the
chest-wall begins opposite the inner end of the spine of the
scapula on the level of the spinous process of the third thoracic
vertebra, then passes obliquely downward and forward to the
outer end of the sixth costal cartilage. This marks the separa-
tion between the two lobes of the left lung.

312 ESSENTIALS OF HUMAN ANATOMY.

The riglit infrrJoJnilnr incisure starts on the same level as
that which marked the left one, descends obliquely over the
posterior axillary line, crosses the inferior angle of the scapula,
and reaches the inferior border of the lung at the mammillary
line on the seventh rib.

The middle incisure starts at the point of intersection of the
posterior axillary line with the " projection-line " of the main
incisure just mentioned ; it passes forward horizontally to the
sternum, ending at the upper part of the sternal end of the
fourth intercostal space. Above this line is the upper lobe
of the right lung, between the fourth and sixth ribs is the
middle lobe, and below the sixth rib is the lower lobe.

THE URINARY ORGANS.

Where are the kidneys situated?

Deeply in the loins, one on each side of the vertebral col-
umn, each kidney reaching from the upper border of the twelfth
thoracic to the third lumbar vertebra, the right a little lower than
the left ; they lie embedded in a mass of fat behind the perito-
neum, and enter four regions — the hypochondriac and epigastric
above, the lumbar and umbilical below.

What are their size and weight ?

Each measures about four inches in length, two and one-
half in breadth, and one and one-quarter or one and one-half
in thickness; they weigh, in the male, from four and one-half
to six ounces ; in the female, four to five and one-half ounces.

Describe their relations.

The anterior surface of the right Mdney is in relation with
the right lobe of the liver, descending duodenum, ascending
colon, and the hepatic flexure.

T\\Q^ anterior surface of the left kidney^ with the great end of the
stomach, lesser sac, tail of the pancreas, and descending colon.

The jiosterior surface of each rests upon the crus of the dia-
phragm and the anterior layer of the lumbar fascia separating
it from the quadratus lumborum and psoas magnus.

The superior extremity is embraced by the suprarenal capsule
and the liver on the right side ; by the capsule and the spleen
on the left side.

The inferior extremities are two inches above the iliac crests.

THE URINARY ORGANS. 313

The right external bonier is covered by the liver, the left by
the spleen.

A fissure, or hihim, one inch long at the central portion of
the internal border, opens into a cavity, the shuts; through it
pass the lymphatics^ also the renal vein in front, the renal
artery next, and the ureter, or excretory duct, behind and
below.

Describe the naked-eye appearances of a longitudinal sec-
tion of a kidney (Fig. 126).

The kidney proper consists of a

Cortical substance'^, composed of convoluted and straight
uriniferous tubules, blood-vessels, nerves, lymphatics, con-
nective tissue, and Malpighian bodies, and is prolonged down
between the pyramids, forming the cohmins of Berlin ; a fibrous
capsule envelops the organ, passes into the sinus which it lines,
blending with the sheaths of vessels, nerves, and the calices ;
the

Medvllary substance'^ consists chiefly of straight tubuli
uriniferi, " Henle's loops," and blood-vessels, arranged in eight
to eighteen piyramids of Malpiglii'^' , whose apices are embraced
by the calices of the pelvis of the ureter ; the

Pelvis consists of eight calices, cup-like tubes, embracing
the apices of eight to eighteen Malpighian pyramids, con-
■ verging to form two infnidibnla, these again joining to form
the jfclvis, which gradually contracts into the 7ireter or ex-
cretory duct.

Describe the tubuli uriniferi'^ (Fig. 127).

They commence in a dilatation called the cajisule of Bow-
man^, which encloses a vascular Malpifjhian fnff, and terminate
by opening on the free surfaces of the papillae '^ Next follows
the neclc, and the

Proximal convoluted tubule^, the much convoluted portion
after leaving the capsule of Bowman and situated in the corti-
cal portion.

The spiral tubule of Schachowa\ next succeeding, where the
tubule approaches the medullary portion in a spiral manner ;
now entering the medullary portion, the tubule suddenly be-
comes smaller, (juite straight, dipping down into the pyran)ids,
as the descending limb of llenles loop; forming a hjop ^ it

314

ESSENTIALS OF HUMAN ANATOMY.

enlarges, ascends spirally, diminislics its caliber, and reenters
the cortical substance, ascending limb of Uenlen loop' ^ ; next

ret

Fig. 126— a longitudinal section of the kidney (Leidy).

it becomes angular, the irregular tubule, then convoluted, called

the

Distal convoluted tubule^^, '\ which terminates in a narrow

Curved or Junctional tubule '^ and finally joins the

Straight collecting fubule^'\ ^\ terminating on the summit

of one of the papillae.

Describe these straight tubules ^'\ ^\

Traced into the pyramids from the papillae, they run from

THE URINARY ORGANS. 315

tlie apex to the base, dividing dichotomously, receiving the
curved tubules, to enter the cortex much increased in number,
where they form conical masses, called the pyramids, of Fer-
rein, with their bases toward the medullary portion.

Describe the epithelium of the uriniferous tubules.

It varies in different portions, being flattened, polyhedral,
angular, striated, and columnar.

Describe the Malpighian tufts, or vascular glomeruli.

Each is formed by a renal afferent^ (Fig- 128) arteriole,
which, after piercing the capsule — a pouch-like commencement
of a tubulus uriniferus lined with flattened epithelium ^ —
breaks up into a tuft of vessels forming a plexus, from which
arises the efferent ^ vessel or vein. These vessels are opposite
the neck of the tubule, emerging from the capsule near the
point of entrance of the afferent arteriole. The Malpighian
tuft or glomerulus, surrounded by the capsule of Bowman,
forms the two parts of the Malpigldan body or corpuscle.

Describe the renal circulation.

Renal artery^from the aorta, gives small branches to the supra-
renal capsule, ureter, and surrounding tissue ; two renal arteries
on one side are frcfjuent ; it divides just external to the hilum
into four or five primary branches, which subdivide to form the

Arterise 2^rf^J>''i^^ rencdes, lying in the columns of Bertin ;
two of these run along the sides of each Malpighian pyramid,
giving off afferent branches to the Malpighian tufts, and,
bending between the bases of the pyramids and cortex, send
off the (1) mferlobular bi-anches and (2) arteriolse rectse :

(1) Tntcrlobvlar arteries., passing outward between the pyra-
mids of Ferrein to the capsule, terminating in .stellate plexuses
beneath it (stars of Verheyen), and also supplying afferent
art<'rioles to the Malpighian tufts of the cortex, whence issue
effer(;nt vessels, forming a dense venons plexus around the
adjacent uriniferous tubules ;

(2) Arteriohi', rectn .^ or desee^idine/ brandies., passing from the
bases to the apices of the pyramids, there to terminate in the
venous plexuses.

The blood is collected by the stellate venous 2>lcxiises beneath'

;i6

ESSENTIALS OF HUMAN ANATOMY.

the capsule, forming vensa infcrlohnlarea^ which pass between
the pyramids of Ferrein, are joined by branches emptying the
plexuses around the convoluted tubes of the cortex, and join
the venae recta) at the bases of the Malpighian pyramids ; these
vense rcctse being branches from ^>/f.T?<.sr.s at the apices of the med-
ullary pyramids formed by the arteriolae rectae. The junction

'^ PuTioapsiilar layer
witluiut >ial-
pi^'hian corpus-
cles.

^) Cortex.

Inner stratum of cortex, without
Malpighian corpuscles.

Fig. 127— Uriniferous tubule (Leidy).

of the ven^ rccf^ and vcnse iiiterlohularrs forms the vcnx proprise
renales, accompanying the arteries of the same name, which
receive venous twigs from the IMalpighian tufts of the cortex
and unite in the sinus to form the

Renal, or cmnlgevt vein, which passes out of the hilum to
empty into the inferior vena cava, the right vein being the
shorter.

THE URETERS. 317

Describe the nerves of the kidney.

They are small, about fifteen in number, have ganglia de-
veloped upon them, and come from the solar plexus, lower and

Fig. 128.— a Malpighian body or corpuscle (Leidy).

outer part of the semilunar ganglia, and from the lesser and
smallest splanchnic nerves, forming the renal i^lexus^ com-
municating with the spermatic plexus.

The Ureters.

What is the ureter?

It is the tubular, cylindrical, excretory duct of the kidney,
of the size of a goose-quill, fourteen to sixteen inches long,
extending from the sinus of the kidney to the base of the
bladder, into which it opens by a constricted orifice, after
having passed obliquely for nearly an inch between its muscu-
lar and mucous coats ; it has a Jihrous coat continuous with the
capsule of the kidney and fibrous tissue of the bladder, a
mnsryJar coat composed of two longitudinal layers and a
middle circular layer, a mucous coat covered with several layers
of many-shaped epithelial cells, "transitional" epithelium.

Describe its course and relations.

It passes obliquely downward along the posterior abdominal

318 ESSENTIALS OF HUMAN ANATOMY.

wall beneath the peritoneum, over the iliac arteries, behind the
ileum on the riylit side, and sigmoid flexure on the le/f, enters
the posterior false ligament of the bladder in the male, with
the vas deferens between it and the bladder, and enters the
bladder obli({uely about one and one-half inches behind the
prostate, and two inches from its fellow ; the internal openings
are 20 mm. apart ; in the female it passes along the upper })art
of the vagina and the side of the cervix uteri, being about
three-fifths of an inch distant from the latter ; the right ureter
lies close to the outer side of the inferior vena cava.

The Bladder.

What is the bladder?

The musculo-membranous reservoir for the urine, situated
between the os pubis and rectum in the male, or between the
OS pubis, cervix uteri, and part of the vagina in the female ;
moderately distended its dimensions are from above downward
and backward 14 cm.; breadth, 12 cm.; antero-posterior diam-
eter, 10 cm.; capacity, about one pint; in the child it is an
abdominal organ and conical ; in the adult, w^hen empty, it may
be Y-shaped, when distended, ovoid. The bladder has a summit
and five surfaces, superior, postero-inferiov or hcise, antero-infe-
rior or pubic, and two lateral surfaces or sides.

Summit'^^ (Fig. 131) is connected with the umbilicus by a
fibro-muscular cord, the uraclius, and by two fibrous cords, one
placed on each side, the obliterated fetal hypogastric arteries;
the antero-iu fieri or surface lies against the posterior surface of the
pubes, triangular ligament, internal obturator muscles, and —
when distended — abdominal walls ; the superior surfiace, being
covered by peritoneum, has some coils of small intestine inter-
posed between it and the rectum and uterus in the female ; the
obliterated hypogastric arteries cross its sides obliquely from
below, upward and forward, all below them being uncovered
with peritoneum ; the vas deferens curves from before back-
ward along each side to reach the base of the bladder passing
across the obliterated hypogastric vessels and along the inner
side of the ureter ; the

Fundus or base (Figs. 129 and 131") is directed downward
and backward, resting in the male upon the second portion of the
rectum, in the female upon the lower part of the cervix uteri,

THE BLADDER.

319

being adherent to the upper part of the vagina, but separated
from the cervix by a fold of peri-
toneum which is reflected so as to
cover a small portion of its base ;
in the male the peritoneum passes
from the rectum to the same portion
of the base.

The bladder has no proper neck
or cervix.

Fig. 129.— Posterior surface of
the bladder ; vasa deferentia
and vesiculse seminales ( Leidyj.

How is the bladder held in place ?

By five true and five false liga-
ments; the true, being made of
fascia, are

Anterior.^ or puho-prostatic,
formed by two folds of the recto-
vesical fascia extending from
either side of the pubic symphysis
to the pubic surface of the bladder over the upper surface of
the prostate gland ;

Lateral, of the same tissue, passing between the lateral sur-
faces of the prostate gland and sides of the base of the bladder
to the pelvic wall ;

Urachiis'^'^ (Fig. 131), a fibro-muscular cord covered with
peritoneum, stretching from a point 4 to 20 mm. anterior to
the apex of the bladder to the umbilicus.

The false ligaments are :

Ty:o posterior, folds of peritoneum passing, in the male from
the sides of the rectum, in the female from the sides of the
uterus, to the postero-lateral aspect of the bladder, and con-
tain the obliterated hypogastric arteries, the ureters, vessels,
and nerves.

Two lateral, peritoneal folds passing from the iliac fossa) to
the sides of the bladder.

Superior '^^ (Fig. IIU), a peritoneal fold passing over the
uracil us, plica nrachi, from near the apex of the bladder to
the umbilicus.

What is the urachus" (Fi<?. 131)?

The remains of a tubular canal connecting the bladder with
the allantois : it has a stalk and may enclose a hollow space.

320

ESSENTIALS OF HUMAN ANATOMY.

Describe the structure of the bladder.

It has four coats, viz. a

FcritoneaP^^ '^^ (Fig. 131), covering the superior surface
from the entrance of the ureters at the base to its summit,
pas.sing on to the sides, whence it is reflected to the abdominal
and pelvic walls : a

Muscular, consisting of fibers spirally arranged, forming
figure-of-eight loops, the more superficial being nearly longi-
tudinal, the deeper nearly circular, and finally a thin internal
longitudinal layer ; these form several more or less distinctly
marked layers, the loops directed toward, and embracing the
urachus and urethra respectively, the aggregation of these
loops around the beginning of the urethra forming the
sphincter vesicse ; the fibers passing in all directions are con-
tinued into the prostatic urethra (Pettigrew) : the

Submucous coat is a layer of areolar tissue intimately blended
with mucous membranes binding it to the muscular coat ; a

Mucous coat, covered by transi-
tional epithelium, the superficial
layer of polyhedral cells, below club-
shaped and smaller spindle-celled ; it
contains a few mucous follicles and
numerous racemose glands lined with
columnar epithelium near the neck ;
it is thrown into folds or rugi£ when
the bladder is empty.

What are the muscles of the ure-
ters?

Two oblique bands rising behind
the orifices of the ureters which con-
verge, to be inserted bv a fibrous
process into the middle lobe of the
prostate gland.

What is the trigonum vesicse or
trigone vesical- (Fig. 130)?

A triangular smooth surface at
the base of the bladder, with apex
forward, of a paler color than the re-
mainder of the mucous membrane,
which is intimately adherent to the subjacent tissue : the

Fig. 130.— The bladder and
urethra laid open (Leidy).

THE MALE URETHRA. 321

Lateral boundaries are two slightly marked ridges on each
side passing backward and outward from the apex, formed by
the urethral opening, to the orifices of the ureters ■^, correspond-
ing to the muscles of these ducts, the openings being placed
one and one-half inches apart (some say 20 mm.) and one and
one-half inches behind the urethral opening ; a line of mucous
membrane connecting the two forms the base of the trigone,
called the plica ureterica.

What is the uvula vesicae* (Fig. 130)?

A slight elevation of the mucous membrane projecting from
the lower anterior portion of the floor of the bladder into the
orifice of the urethra.

Mention the vessels connected with the bladder.

Syperior, middle, and inferior vesical, and small twigs from
the obturator and sciatic arteries in the male, with additional
branches from the uterine and. vaginal in the female ; the veins
form intricate plexus'es around the neck, sides, and base, empty-
ing into the internal iliac vein ; the lymphatics accompany the
ves.sels.

Give the nerve-supply of the bladder.

It is bilateral, coming from the hypogastric plexus of the
sympathetic and third and fourth sacral nerves, sometimes the
second sacral nerve.

The Male Urethra.

Describe this canal.

It extends from the neck of the bladder* to the meatus
urinarius, measuring eight to nine inches ("20.4 cm.), present-
ing a double curve if the penis is flaccid, but a single one with
the convexity downward during erection.

Name and describe each of its divisions.

They are the prostatic ^ \ membranous, and spongy.

The prostatic portion \^ (Y'lQ. 130), that portion passing
from the base to the apex of the prostate gland, running nearer
the upper surface, measuring one and a (juarter inches long, is
the widest and most dihitable section of the urethra and is
spindle-shaped ; upon the median aspect of the floor is a nar-

21

322

ESSENTIALS OF HUMAN ANATOMY.

row longitudinal ridge eiglit or nine lines long, three-quarters
of an inch, the vertimontanum or caput gaUinagiids^, containing
muscular and erectile tissue ; on either side is a slight fossa,
called the prostatic sinus, its floor presenting the openings of
the lateral prostatic ducts ; the ducts of the middle lobe open
above the vermnontanum.

The sinus pocularis, or vtn-ns masculinus ^, is a depression
extending about a quarter of an inch upward and backward
beneath the middle lobe of the prostate in the median line at
the forepart of the verumontanum, upon or within whose mar-
gins are the slit-like orifices of the seminal or ejaculatory ducts^.

The membranous ])ortion^ is th^t portion, three-quarters of
an inch long, extending between the apex of the prostate and
bulb of the corpus spongiosum, which is included between the
layers of the triangular ligament about one inch beneath the
pubic arch ; it is surrounded by the compressor urethral mus-
cle, and is the narrowest portion of the urethra, except the
meatus.

The spongy portion'^, ^, the longest, measuring about six
inches, is so called from being contained in the corpus spongio-
sum ; it extends from the membranous portion to the meatus
urinarius, and presents a posterior dilatation, that of the bulb ^
(Fig. 131), and one anterior, the fossa navicularis^^ (Fig. 131),

Fig. 131.— a vertical section of the bladder, penis, and urethra (Leidy).

the former having opening into it the ducts of Cowper's glands,
the latter fossa being situated within the glans penis, having an

THE FEMALE URETHRA. 323

opening directed forward in its roof, hiciuia magna, the orifice
of a large mucous crypt ; there are also here numerous other
scattered openings of glands and follicles similarly directed,
glands of Littre.

What is the meatus urinarius ?

The anterior orifice of the urethra, a vertical slit about three
lines long, bounded on each side by a small labium ; it is the
narrowest portion of the canal.

Describe the structure of the urethra.

It possesses four coats, viz. a mucous, forming a part of the
genito-urinary membrane internally and continuous with the
skin externally, having numerous mucous glands imbedded in
its submucous tissue, which open on its free surface ; it is
covered with columnar epithelium except near the meatus,
where it is squamous.

The suhmucons coat is a thin layer of vascular erectile tissue,
surrounding especially the prostatic and membranous portions.

External to this is the muscular coat (muscularis mucosae) ;
in the prostatic portion it consists of an inner longitudinal and
an outer circular layer of unstriatcd muscle-fibers ; they are
directly continuous with the muscle-layers of the bladder.
Both layers are present in the membranous portion and aid
the sphincteric action of the striated urethral muscles. Both
layers gradually cease in the spongy portion, the circular layer
disappearing first; a few oblique and longitudinal fibers remain
in the anterior part of this portion.

A variable y?^>Y>»s tunic surrounds the muscular layer, giving
support and strength to the canal.

The Female Urethra.

Describe this canal.

It is about one and one-half inches long, extends from the
]>ladder to the meatus urinarius above the anterior vaginal wall,
pierces the triangular ligament, and is embraced by the com-
pressor nrcthnii muscle as in the male ; its structure is similar to
that of the rmile urethra; it is lined with laminated squamous
epithelium merging into spheroidal near the bladder; it is a
quarter of an inch in diameter, but is capable of much greater

324 ESSENTIALS OF HUMAN ANATOMY.

dilatation ; the anterior opening (meatus) is situated near
the anterior margin of the vagina, about one inch behind the
clitoris, surrounded by a prominence of mucous membrane.

THE MALE GENERATIVE ORGANS.

Where is the prostate gland situated (Fig. 130)?

It surrounds the neck of the bladder and commencement of
the urethra, lying in the pelvic cavity posterior to the deep
perineal fascia, behind and below the symphysis pubis upon the
rectum ; through it pass the urethra and ejaculatory ducts.

Describe its form and size.

It resembles a horse-chestnut in form, measures one and a
half inches transversely, one inch antero-posteriorly, three-
quarters of an inch in depth, and weighs four and a half to
four and three-quarters drachms ; the base is directed backward
toward the bladder ; it consists of two equal-sized lateral lobes
and a middle lobe, which is a small band or rounded triangular
eminence placed between the lateral lobes immediately in front
of the base of the bladder and below the commencement of the
urethra.

Describe its structure.

It is composed of numerous follicular pouched glands open-
ing into elongated canals which join to form twelve to twenty
excretory ducts imbedded in the interstices of a stroma formed
of interlacing bundles of unstriped muscle, the whole being
inclosed in a fibrous capsule. Muscular tissue predominates
over the glandular.

What retains the gland in place ?

The pubo-prostatic ligaments, posterior layer of the deep peri-
neal fascia, and anterior portions of the levator ani muscles.

Describe the situation and structure of Cowper's glands.

They are two small lobulated glands of the size of peas,
lying between the two layers of the deep perineal fascia in
front, close behind the bulb of the urethra, surrounded by the
compressor urethrae muscle, and opening by ducts one inch
long which pass obliquely forward beneath the mucous mem-
brane, on the floor of the bulbous portion of the urethra.

THE PENIS. 325

The Penis.

Describe the penis.

It has a root, body ^ (Fig. 131), and extremity or glans
penis ^, and consists of three elongated cylindrical masses of
erectile tissue, composed of a fibrous sheath which sends
inward numerous interlacing bands (trabeculae), forming nu-
merous meshes in which lie the blood-vessels. The upper two
cylindrical bodies lying side by side, like a double-barrelled
gun, are called the corpora cavernosa ^ ; the third, much smaller,
lying in the median line beneath, like the ramrod of a gun, is
the corpus spongiosum.'^

Describe the corpora cavernosa.

Situated as just described, they are intimately connected in
their anterior three-fourths, where they are in contact, present-
ing a median dorsal groove for vessels and nerves, and an inferior
median groove for the corpus spongiosum, while their posterior
fourths diverge, forming the crura *, which are attached to the
rami of the pubes and to the ischia anterior to the tuber-
osities ; near their point of junction with one another they
become slightly enlarged, forming on either side the bulb of
the corjnis cavernosum.

What other structure secures the root of the penis ?

The sxspensior}/ ligament, a band of fibro-elastic tissue, con-
nected with the symphysis pubis and superficial fascia, which
runs to the dorsum of the penis.

What is the septum pectiniforme ^ ?

It is the anterior portion of the vertical septum between the
corpora cavernosa which is incomplete, the fibrous bands re-
sembling the teeth of a comb ; the septum and fibrous sheath
contain numerous elastic and muscular fibers in addition to the
white fibrous tissue.

Describe the corpus spongiosum.

It incloses the urethra '^ lying mcdianly below at the junc-
tion of the corpctra cavernosa, commencing beliind in front of
the deep perineal fascia between the crura of the corpora caver-
nosa as a rounded enlargement, the bulb **, which is surrounded

326 ESSENTIALS OF HUMAN ANATOMY.

by tlie accelerator urini© muscle. Anteriorly it forms a coni-
cal enlargement, flattening from above downward, which caps
the blunted end formed by the corpora cavernosa, the glans
jyenis^, the margin of whose base is called the corona glandis^
and the constriction behind, the cervix.

What other parts of importance does the penis present ?

The medtaa nrinarias, the external orifice of the urethra, is a
vertical opening at the summit of the glans penis.

The prepuce., a portion of the skin of the penis prolonged
forward so as either completely or partially to cover the glans
penis, lined with modified skin which covers the glans and
joins the mucous membrane at the meatus.

Frenum preputii^ a median fold of integument passing from
behind the meatus at the bottom of a depressed raphe to
become continuous with the under margin of the penis.

Glaiidnlse TysonU odoriferse,, numerous small lenticular se-
baceous glands upon the corona and cervix of the glans,
secreting sebaceous matter with a peculiar odor.

What is meant by erectile tissue ?

An intricate venous plexus formed by the interspace between
the fibrous trabeculse, the blood being delivered in the follow-
ing ways : (1) by arteries terminating in ordinary capillaries —
this is the arrangement in the corpus spongiosum and glans ;
(2) by fine convoluted arterial twigs opening directly into the
venous network by funnel-shaped extremities.

What are the helicine arteries?

Convoluted, tendril-like arterial branches opening directly
into the intertrabecular spaces, as just explained, most
abundant in the back parts of the spongy and cavernous
bodies.

Name the vessels, lymphatics, and nerves of the penis.

The arteries are all branches of the internal pudic, viz.
Artery of the bidh, on each side, to the corpus spongiosum.
Arteries of the corpora caver)iosa, to these bodies.
Dorsal arteries of the jjenis, to the corpora cavernosa, glans,
prepuce, and skin. The veins return the blood by the dorsal

THE TESTES AND THEIR COVERINGS. 327

vein, prostatic and pudic venous plexuses ; also by the pudic
and obturator veins.

The superficial lymphatics end in the inguinal glands, the
deep join the deep pelvic lymphatics.

The nerves are branches of the internal pudic and hypo-
gastric plexus of the sympathetic.

The Testes and their Coverings.

What are the testes or testicles (Fig. 132)?

They are the procreating glands, those which secrete the
spermatozoa, are of ovoid form compressed laterally, and are
each obliquely suspended in the scrotum by the spermatic cord.
They measure in length one and a half inches (o7 mm.), one
inch in breadth (24 mm.), and one and a quarter inches antero-
posteriorly (28 mm.), weighing from six to eight drachms, the
left being slightly the larger.

What is the scrotum?

A cutaneous pouch containing the testicles and part of the
spermatic cords, formed of integument externally and beneath
this of a reddish contractile layer, the dartos, continuous with
the contiguous superficial fascia and sending inward a parti-
tion, the septum scroti, dividing the scrotum into two compart-
ments.

Describe the coats of the testis.

They are, the tunica vaginalis, a serous coat originally derived
from the peritoneum, consisting of a portion investing the testis
and epididymis, the visceral layer, or tunica vagin((lis propria,
and a parietal layer, or tunica vaginalis reflexa ; the

Tunica alhuginra is formed of white fibrous tissue surround-
ing tlie gland and reflected into its interior at its postero-supe-
rior border to form an incomplete vertical partition, the meili-
astinum testis, or corpus Jfigliniori, from which filtrous septa
pass, frahecuhe, separating the glandular lo])ul('S ; the

Tunica vasculosa, or pia mater testis, consists of a plexus of
blood-vessels bound together by areolar tissue, which invests
the inner surface of the tunica albuginea and sends off proc-
esses between the lobules.

328 ESSENTIALS OF HUMAN ANATOMY.

What is meant by the coverings of the testis?

The structures with which the testes become invested in
their passage, previous to birth, from the abdomen along the
inguinal canals into the scrotum.

Name these coverings.

J. ' [■ scrotum, closely adhering to each other.

Inter columnar^ or external spermatic fascia, derived from the
margins of the external abdominal ring.

Cremaster muscle and fascia^ derived from the lower border
of the internal oblique muscle (some authors deny this).

Infundihuliform, or fascia 2)rojwia, a downward continuation
of the infundibuliform process of the transversalis fascia.

Subperitoneal areolar tissue comes next, then the tunica vag-
inalis, derived from the peritoneum.

Describe the structure of the testis.

It consists of some eight hundred to nine hundred seminif-
erous tubules, one-two-hundredths to one-one-hundred and fifti-
eth of an inch in diameter, convoluted so as to form three hun-
dred conical lobules, with apices toward the mediastinum ; the
tubes then unite to form twenty or thirty larger ducts, one-
one-fiftieth of an inch in diameter, called the vasa recta", which,
passing upward and into the mediastinum, form a close network
of anastomosing tubules, the rete testis; these at the upper end
of the mediastinum terminate in twelve to twenty vasa effer-
entia\ perforate the tunica albuginea, and become enlarged and
convoluted, forming coni vasculosis, W'hich aggregated compose
the globus major of the epididymis ; the tubules consist of a
membrana propria lined with a layer of polyhedral cells, with
two or more inner layers of spheroidal cells, which divide into
epithelial cells ultimately to become converted into spermatozoa;
the vasa recta and tubes of the rete testis have thin w^alls lined
with one layer of squamous cells ; the vasa eifercntia and epi-
didymis have thicker walls, containing muscular tissue, and are
lined with columnar epithelium.

What is the epididymis?

A convoluted tube, some twenty feet long, lying along the
posterior border of the testis, commencing on the testicle side

THE TESTES AND THEIR COVERINGS. 329

by a convergence of the tubes of the coni vasculosis and ending
in the single vas deferens beyond.

Describe its various parts.

The glohiis major ^ is formed by the coni vasculosi, or efferent
dticfs, which open at intervals into the single duct forming the
epididymis ; the

Bodij^ is the central portion, formed by the convolutions of
the tube bound together by delicate areolar tissue ; the

Globus minor ^ is the lower enlarged portion, composed as the
body is, and connected to the testis by fibrous bands and areo-
lar tissue ; the

Vas aherrans is a narrow tube, occasionally extending up into
the cord for two or three inches, and ending in a blind ex-
tremity, connected with the lower part of the tube of the epi-
didymis, or commencement of the vas deferens ; the

Hydatids of Morgagni are small bodies attached to the globus
major or upper portion of the testicle by pedicles ; they are
probably the remains of the duct of M'dller ; one is very con-
stant.

Describe the vas deferens'^.

It is the excretory duct of the testis, and is a continuation
of the epididymis, commencing at the globus minor ^ to ascend
along the posterior side of the testis and epididymis, back of
the spermatic cord, through the inguinal canal to the internal
abdominal ring, whence, passing into the pelvis, it crosses the
external iliac, curves around the epigastric artery to reach the
side, then by a curve downward and backward, the base of the
bladder internal to the ureter^ (Fig. 129) ; here it lies between
the bladder and the rectum, coursing along the inner border of
the seminal vesicle^, becoming enlarged and sacculated, the am-
pulla, but narrowing at the base of the prostate, where, joined
by the duct of the vesicula seminalis^, it forms the ejaculatory
diict^. It is one foot long, or two if unravelled, is about one
and a quarter lines in diameter, its lumen but one-third line
(0.7 mm.) ; it has thick, rigid walls, presenting a hard, cord-
like sensation when rubbed between the fingers.

What are the vessels of the testis and its coverings ?

The gland itself is supplied by the spennatic artery"" (Fig-

330

ESSENTIALS OF HUMAN ANATOMY.

132), the coverings receive blood from the siipprftcial external

pmlic and the deep external
puilic from the femoral, super-
ficial perineal from the inter-
nal pudic, cremasteric from the
epigastric, and artery of the vas
deferens from the superior
vesical.

The veins leave the back of
the testicle, forming the jiam-
piniform p)lexus^ which ends
in a single trunk emptying on
the right side into the inferior
vena cava, on the left into the
left renal vein.

Veins of the same name as
the arteries supplying the cov-
erings, return blood to the fem-
oral, external, and internal
iliac veins.

Fig. 132.— Vertical section of the
testicle (Leidy).

What nerves go to each testi-
cle and its coverings ?

Branches from the spermatic plexus of the sympathetic to
the testicle itself, to the coverings and cord the ilio-iuguinal,
ilio-liypogastric^ tiro superjicial perineal, inferior pudendal, and
genital branch of the genito-crural nerve.

What are the component parts of the spermatic cord ?
Vas deferens, Spermatic nerve-jdexus,

Spermatic artery, Branch of the ilio-inguinal nerve,

Cremasteric artery, Branch of the genito-crural nerve,

Artery of the vas deferens, Vas aherrans (inconstant),

Lymphatics,

Remains of the peritoneal jwnch.

These form a cord bound together by connective tissue, in-
vested by fascine brought down by the testicle, about four
inches long, extending from the globus minor to the internal
abdominal ring.

Describe the vesiculse seminales.

They are two lobulated membranous receptacles for the

Spermatic veins,
Areolar tissue,

THE FEMALE ORGANS OF GENERATION. 331

semen, which they dilute with their own secretion. They are
pyramidal in form, are about two inches (50 mm.) long by five
lines broad, by two to three lines thick, and lie in contact
with the base of the bladder, diverging from each other from
the base of the prostate to near the entrance of the ureters ;
they join by their anterior pointed extremities with the vas
deferens, forming on each side the ejaculatory diict'^ (Fig. 129),
terminating in the prostatic urethra by a slit-like orifice on each
side, just upon or within the margin of the sinus poadaris^
(Fig. 130) at the front of the verumontanum.

Describe the descent of the testes.

During early fetal life the testes lie at the back part of the
abdomen, behind the peritoneum, just below and in front of
the kidneys ; attached to the lower end of the epididymis, and
attaining its full development from the fifth to the sixth fetal
month, is the gubeniacnlmn testis, vi\\\Q\\ contains muscular tis-
sue ; this divides below into three portions, passing to Pou-
part's ligament, to the os pubis and rectus muscle, and to the
dartos at the bottom of the scrotum ; the gubernaculum is
supposed to contract and so cause descent of the testicle, but
this is a moot point. Between the fifth and sixth months each
testis reaches the iliac fossa, by the seventh it enters the inter-
nal abdominal ring, by the eighth month it has reached the
scrotum, invaginating from behind the preformed peritoneal
sac, jJ7'oc*:^s.s>/.s vaginalis, the upper part of which usually
becomes obliterated just before birth, the lower portion then
forming the tunica vaginalis testis completely cut off from the
abdominal cavity ; the other structures in front of the testis
are likewise carried onward, forming its covering, as already
described.

THE FEMALE ORGANS OF GENERATION.

What is the vulva (Fig. VA?,)?

The term includes the following organs :

Lahia 7ninora '^ Vaginal orifice ^^,

Mons Veneris*, Clitoris^,

Lahia majora ^, Meatus vrinarius '*.

These parts are also called the ^mdendmv and external
organs of generation.

332

ESSENTIALS OF HUMAN ANATOMY.

Describe the mons Veneris*.

It is a rounded eminence surmounting tlie vulva in front of
the symphysis pubis, formed by a collection of fatty tissue,
and at puberty becomes covered with hair.

Describe the labia majora^ and minora '\

The labia majora^ 2Lxe two prominent longitudinal cutaneous
folds passing downward from the mons Veneris to the anterior
part of the perineum, enclosing the common urogenital space.
Each labium is formed externally of hair-covered skin, inter-
nally of skin, enclosing between these hiyas fatty areolar tissue
and a structure resembling the dartos of the scrotum, to which
they correspond; the junction of the labia in front constitutes
the anterior commissure ; the posterior commissure isafold of skin.

The labia minora, or nymphse,'^^, are two thin cutaneous folds
containing numerous sebaceous glands, inside the labia majora,
running from the clitoris'' — where they form a hood-like pre-
puce and frenum — obliquely downward for about one and a
half inches on each side of the vaginal orifice, to be lost in the
labia majora.

Describe the remaining structures forming the vulva.

The clitoris^ is a small penis with root, body, and glans,
composed of two corpora cavernosa formed of erectile tissue

attached to the rami of the pubes and
ischium by two crura ^; it has a sus-
pensory ligament and two erectores
clitoridis muscles.

The vestibuleis the triangular smooth
surface below the clitoris, bounded on
each side by the labia minora.

The meatus iirinarius^* is placed at
the back part of the vestibule, about
one inch below the clitoris, near the
vaginal margin, surrounded by a
prominence of mucous membrane.

The vaginal orifice ^^ is of an ellipti-
cal form, usually more or less closed
in the virgin by the hymen, and is
surrounded by the sphincter vaginae
Fig. 133.— The vulva, or muscle, the analogue of the male ac-
external generative organs ^pi„„„^„_ urinv mil sole

THE VAGINA. 333

The hymen is a thin fold of mucous membrane, variously
shaped, but usually that of a ring broadest behind, or semi-
lunar, with its concavity upward, stretched across the lower
part of the vaginal orifice ; it may occasionally form a com-
plete occluding membrane, the condition being then known
as imperforate hymen; it may be practically absent in the
virgin, and again may persist after copulation, but at that
time is usually ruptured ; after parturition it gives rise to
small, rounded elevations surrounding the vaginal outlet, called
carunculse myrtiformes.

^ The glands of BarthoUn^^ arc small, oblong, reddish-yellow
bodies, lying on each side of the commencement of the vagina,
each opening by a long single duct external to the hymen on
the inner side of each labium majus ; they correspond to
Cowper's glands in the male.

The halbi vestibuU^'^ are two oblong masses — a venous plexus
enclosed in a fibrous envelope — extending from the clitoris
along each side of the vestibule, a Httle behind the labia
majora.

The pars intermedia '^ is another small venous plexus imme-
diately in front of the preceding, with which it is continuous as
well as with the glans clitoridis ; these plexuses correspond to
the corpus spongiosum.

The fourchette is a small transverse cutaneous fold, just
within the posterior commissure ; it is the junction of the
labia minora.

The fossa navicidaris is the space between the fourchette
and the hymen ; it is generally artificial, not normal.

The Vagina.

Describe it.

It is a cylindrical membranous canal flattened from before
backward, lying between the rectum and the bladder, extending
from the vulva to the uterus, curved backward and upward,
conforming to the axis of the pelvis and of the outlet. Narrow
at its orifice, it is larger above, its anterior wall measuring
about two and a half inches, its posterior three and a half, being
attached higher up on the cervix uteri behind than in front.

Describe its structure.

It is formed of an external layer of fibrous tissue, a muscu-

334 ESSENTIALS OF HUMAN ANATOMY.

lar coat, and a lining mucous membrane with a median anterior
and a posterior raphe or ajhinins of the cayina^ which give oflF
transverse rugae ; mucous glands are absent ; the epithelium
is squamous.

Give the relations of the vagina.

Its anterior surface is in relation with the base of the bladder
and urethra ; the jwsterior surface is in relation with the rec-
tum, its lower four-fifths being separated from it by the peri-
neum and connective tissue, its upper fifth by a recto-uterine
fold of peritoneum, forming Douglass cul-cle-sac ov jjouch.

Laterally^ above it gives attachment to the broad ligaments
of the uterus, below to the levatores ani muscles and recto-
vesical fascia.

The Uterus and its Appendages.

Describe the position and parts of the uterus (Fig. 134).

It is the organ of gestation, situated in the pelvic cavity
between the rectum and bladder, opening below into the vagina,
which is attached around its cervix. It is pear-shaped, flat-
tened from before backward, is about three inches long, two
inches in breadth at the upper part, and one inch thick, weigh-
ing from one to one and a half ounces (33 to 41 gm.) ; it pre-
sents for examination the

Funchis"^^ which is convex, covered with peritoneum, and
placed below the level of the brim of the pelvis ; the

Body gradually narrows from the fundus to the neck, with
the anterior flattened surface covered with peritoneum as far as
the internal os. and a posterior peritoneum-covered convex sur-
face, while each lateral margin is concave, afi'ording attachment
to the Fallopian ^ tube above, to the round ligament in front
and below this, and to the ovarian ligament below and behind
both ; the

Cervix'^ \'^ the lower, rounded, constricted portion of the
uterus, which lies partly above the vagina and partly within
it ; it consists of three zones, upper, lower, and middle ; supra-
vagincd^ intravagincd, the middle zone affording attachment to
the vaginal walls.

Cavity of the body is small, triangular, flattened from before
backward, its upper extended lateral angles being funnel-

THE UTERUS AND ITS APPENDAGES.

335

shaped, at the apex of which each opens by a minute orifice
into the Fallopian tube ; at the inferior angle is the small open-
ing into the cavity of the cervix called the os interauni or inter-
nal OS uteri ; the

Fig. 134.— Anterior view of the internal generative organs (Leidy).

Cavity of the cervix is spindle-shaped, flattened antero-pos-
teriorly, and opens into the cavity of the uterus above by the
internal os uteri, and below into the vagina by the external os
uteri ; a median longitudinal crest of mucous membrane on the
back and front walls, from which proceed obliquely upward
other smaller ones, forms the arbor vitse uterina, hardly notice-
able after the first labor ; the

Os externum or external os uteri (also os tineas)* is a trans-
versely ovoidal opening from the cervix into the vagina, which
presents an anterior and a posterior lip, both in contact with the
posterior vaginal wall.

Describe the ligaments of the uterus.

Six are peritoneal folds, viz.

Anterior or vesico-uterine. two crescentic folds passing be-
tween the uterine neck and the back of the bladder ; the

Posterior or recto-uterine pass from the uterus and vagina to
the sacrum and rectum ; the peritoneal pouch thus formed be-
tween the rectum, the uterus, and the upper fifth of the vagina
being called Douglas s or the recto-uterine pouch ; the

Tu-f) lateral or hroad lif/aments"^ (^ij?- 134), stretched between
the sides of the uterus and the lateral walls of the pelvis, dividing
this cavity into two portions, each containing between its folds
the Fallopian tube", the round ligament'', ovary and its liga-
ment, parovarium, and connective tissue.

336 ESSENTIALS OF HUMAN ANATOMY.

Describe the round ligaments of the uterus ^

They are two muscular cords, four or five iiiclies long, com-
mencing at the superior angles of the uterus to pass forward
and outward through the internal abdominal ring into the in-
guinal canal, to become lost in the labia majora and in the fatty
tissue of the mons Veneris ; they consist of dense fibrous tissue
and unstriped muscle, enclosed, in the fetal state, by a process
of the peritoneum extending a short distance into the inguinal
canal, the so-called canal of Nuck^ usually obliterated in the
adult, but sometimes pervious throughout life ; this corre-
sponds to the processus vaginalis of the male.

Describe the structure of the uterus.

The womb has three coats, viz.

A serous, derived from the peritoneum, covering the fundus
of the organ, its posterior surface, and posterior part of the
cervix ; also the whole of the anterior surface of the body to
a point opposite the internal os.

A muscular, forming the bulk of the uterus, composed of
bundles of unstriped muscular tissue interspersed with areolar
tissue, blood-vessels, lymphatics, and nerves. The fibers are
disposed in three layers, viz. external, in front of and behind the
fundus ; middle la3''ers, passing longitudinally, obliquely, and
transversely ; and internal, arranged in two hollow cones whose
apices surround the orifices of the Fallopian tubes, whose bases
fuse in the middle of the uterine body ; at the internal os these
fibers are circular and sphincteric.

A mucous, thin, smooth, and closely adherent to the subjacent
parts, covered with columnar ciliated epithelium, and contain-
ing numerous tubular follicles, most numerous in the cervix ;
when their ducts become obliterated their secretion is retained,
forming small vesicular elevations within the os and cervix,
called ovula Nahotlii. The epithelium loses its cilia at the
lower third of the cervix.

Name the uterine vessels and nerves.

The arteries are the iifen'ue. from the internal iliac, and ova-
rian. from the aorta, which pursue a very tortuous course and
freely anastomose.

The veins accompany the arteries and terminate in uterine
plexuses ; during pregnancy they are called uterine sinuses,

THE UTERUS AND ITS APPENDAGES. 337

consisting of the lining membrane of the vein adhering to the
walls of canals channelled through the uterine substance ; the
Lymphatics terminate in the pelvic and lumbar glands ; the
Nerves are branches of the inferior hypogastric and sper-
matic plexuses, and of the third and fourth sacral nerves.

What are the Fallopian tubes?

They are the oviducts^ two tubes four to five inches long, ex-
tending between the layers of the broad ligament on each side
from the superior angle of the uterus, passing out for one inch
to the side of the pelvis, then upward, backward, and down-
ward to the inner surface of the ovary. Each has an isthmus,
ampulla, neck, and Jimhriated extremiti/ ; the isthmus is the inner
constricted third of the tube, opening into the uterine cavity
by a bristle-sized orifice ; the amp>ulla is larger, tortuous, curves
over the ovary, and includes one-half of the total length, pass-
ing from the isthmus to the neck. The ovarian end expands
like a trumpet into the Infundlbidum , with its ostium ahdomi-
7iale^^ surrounded by fringe-like Jimhriae, hence the term fim-
briated extremity^^; one band is attached to the ovary, ovarian
fimbria, and has a longitudinal groove. Their walls are formed
of a serous or peritoneal coat, a muscular, formed of longitudi-
nal and circular fibers, and a mucous coat covered with ciliated
columnar epithelium, continuous on one side with the uterine
mucous membrane, on the other with the peritoneum.

Describe the ovaries".

They arc two flattened, ovoid bodies suspended by their an-
terior margins from the back of the broad ligaments^ in loops
of the Fallopian tubes ; they have mesial and lateral surfaces,
posterior and anterior borders, upper and lower extremities
(His) ; they are attached by their lower extremities to the
uterus, by the ovarian ligaments and by their upper ends to
one of the fimbria? of the Fallopian tube ; their dimensions
are: leiuffh, one and a half inches; uidth, three-fourths of an
inch ; thickness, one-half inch.

Describe the structure of the ovaries.

Tlicy consist of numerous (iraafian follicles embedded in a
fibrous stroma, covered extermilly by modified peritoneum, hav-

22

338 ESSENTIALS OF HUMAN ANATOMY.

inf; columnar instead of squamous cells of a dull white appear-
ance.

The stroma consists of numerous spindle-cells with con-
nective tissue and abundant blood-vessels ; a condensed periph-
eral layer under the epithelium was formerly described as the
tunica albuglnea. The stroma has elastic and muscular tissue.

What are the Graafian follicles?

Ovisacs, minute vesicles, 70,()()0 at birth, diameter from y^^
inch (0.25 mm. ) to the size of a currant when ready to rupt-
ure ; microscopically they are seen to consist of an external
Jihro-vascular coat connected with the stroma by a vascular
network, and an internal coat, or ot'icajjsule, lined with a layer of
nucleated cells, the membraiia gramdosa^ which are heaped up
around the ovum at that part of the Graafian follicle nearest
the ovarian surfiice. forming the discus jyroligerus ; the follicle
contains also a transparent, albuminous fluid, liquor follicuU,
supporting the ovum.

Describe the human ovum.

It is a spherical mass of protoplasm, yl-g- inch (0.2 mm.) in
diameter, just visible to the naked eye, and consists of the

Vitelline membrane, zona pellncida, or. best, zona radiata, as
it possesses strij» thought to be pores ; it surrounds the

Vitellus, or ?/olk, a fluid containing granules, protoplasm, deu-
toplasm, and a nucleus ^-I-q inch (0.05 mm.) in diameter; the
nucleus is the

Germinal vesicle, containing a smaller body, or nucleolus, the

Germinal spot, -^-^-^ inch in diameter.

What is a corpus luteum?

An irregular y tallow spot in the ovary at the site of a rupt-
ured Graafian follicle, which diff"ers in appearance according as
it is a true or false corpus luteum.

Describe the differences between these two kinds.

The true corpus luteum is that of pregnancy ; it is single and
increases up to a certain point, at the fifth month occupying
sometimes the greater part of the ovary, and usually does not
entirely disappear until one or two months after delivery.

The false corpus luteum is that following ordinary menstrua-
tion ; it is much smaller and disappears in about two months.

THE MAMMARY GLANDS. 339

Name the ovarian arteries, veins, and nerves.

The arteries are the ovarian, from the aorta, anastomosing
with the uterine artery ; these vessels also supply the Fallo-
pian tubes ; the

Veins follow the arteries and form a plexus near the ovary,
called the pampiniform plexus.

The nerves are derived from the inferior hypogastric or pelvic
plexus, and from the ovarian plexus ; the Fallopian tubes re-
ceive branches from the uterine nerves.

What is the parovarium?

It is also called the organ of Rosenmiiller ; it is the remains
of a fetal structure, and in the adult consists of a few closed
convoluted tubes lined with epithelium, one commonly ending
in a bulbous hydatid-like swelling ; at its tubal end the parova-
rium is connected with the remains of the Wolffian duct — the
duct of Gartner.

THE MAMMARY GLANDS.

Describe the mammae.

They exist in both sexes, being in the male only rudimen-
tary, but in the female are two large hemispherical eminences
situated toward the lateral aspect of the pectoral region, reach-
ing from the midaxillary line to the sternum, and from the sec-
ond to the sixth or seventh ribs ; just below the center at the
fourth rib projects a conical prominence, the nij^j^le, surrounded
by a light-colored areola, in which are numerous prominent
sebaceous glands, which enlarge during pregnancy ; the color
of both nipple and areola darkens during pregnancy, and the
latter also extends its area.

Describe the structure of the mammary glands.

They are composed of gland-tissue, of fibrous tissue connect-
ing the lobes, and fatty tissue in intervals between the lobes ;
the lobes consist of lobules formed of a number of rounded
vesicles grouped about a small lactiferous tube into which their
ducts open, and by their union finally form fifteen or twenty
excretory ducts, or tnhidi lactiferi, which converge toward the
areola, dilating beneath it into the ampullar at the base of the
nippl(!, wh(;re they contract into straight tu})OS perforating the
summit of the nipple ; the lobules are surrounded by a dense

340 ESSENTIALS OF HUMAN ANATOMY.

capillary network during lactation, as is also the nipple, which
becomes erected when irritated, partly from fulness of blood,
partly from contraction of its muscular tissue.

Name the vessels and nerves of the mammae.

The arteries are derived from the thoracic branches of the
axillary, intercostal, and internal mammary arteries; the

Veins form an anastomotic circle around the base of the nip-
ple, called the circnlus venosus, from which large vessels radiate
to terminate in the axillary and internal mammary veins ; the

Lymphatics chiefly run along the lower border of the pectoralis
major to the axillary glands, a few pass through the intercostal
spaces to the anterior mediastinal glands ; the

Nerves come from the anterior and lateral thoracic cutaneous.

THE ORGANS OF SENSE.
The Skin and its Appendages.

Of what parts does the skin consist ?

(a) Stratum corneiim,

^ m .1 . ^.7 (b) Stratum, hicidimi,

1. Lpiaermis, or cuticle, ^ < ci^ ^ 7

^ n \ o r (c) Stratum gramdosnm.

formed 01 \ ) i\ a^ ^ * nr 1

I (d) Stratum mucosum^ or rete 3lat-

J J) iff Mi.

2. Dei-ma, cutis vera^ or ] (a) Stratum papillare,

corium, formed of j (b) Stratum reticulare.

3. Stratum suhcutaneum.

Enumerate the accessory structures contained in the skin.

The tactile corpuscles., in the papillae of sensitive parts.

Ducts of the sebaceous^ . ^r i, n - v i r ^i

1 -^ ^ 7 7 I passing through all the layers ot the

and siceat-g lands ^ h V

Hair-follicles^ j

JVails, hairs ^ sebaceous fflands, sudoriferous or sweat-ylands.

Where do sweat- and sebaceous glands with the hair-fol-
licles lie?

Chiefly in the subcutaneous fatty tissue, but sometimes in
the deepest layers of the corium.

THE SKIN AND ITS APPENDAGES. 341

Describe the epidermis.

It is composed solely of epithelial cells, tlie deepest layer
being columnar, more rounded in the middle portions, and flat,
scaly, and horny on the free surface ; the deepest, softest layer
is accurately moulded upon the papillary layer of the derma,
and contains the skin-pigment ; it is called the stratum muco-
r,iim.

Describe the derma.

It is a tough, flexible, and highly elastic tissue, protecting
subjacent parts, and is the chief organ of the sense of touch ;
excretion is effected by its various glands, and absorption also
takes place from its surface. The derma consists of the

Pdpillarij layer^ situated upon its free surface, presenting
innumerable, minute, vascular, conical eminences, averaging in
length one one-hundredth of an inch by one two-hundred-and-
fiftieth of an inch in diameter at their bases, scattered irregu-
larly in slightly sensitive parts, but arranged in parallel curved
lines, forming ridges, in highly sensitive regions ; each papilla
contains one or more capillary loops, and one or more nerve-
fibers, some terminating in oval-shaped bodies, the tactile cor-
puscles, where touch is most highly developed ; Pacinian cor-
puscles lie in the subcutaneous tissue.

Reticular layer contains interlacing bands of white fibrous
tissue, with some yellow elastic fibers, unstriped muscular
fibers wherever hair exists, lymphatics, blood-vessels, and
nerve-plexuses.

What are the nails ?

Flattened, horny structures of modified epithelium, covering
the dorsal aspects of the derma of the distal phalanges of the
fingers and toes. They are convex externally, and have a root,
embedded in a groove of skin, whence comes the growth in
length ; a matrix, that portion of the derma beneath, by which
the nail grows in thickness ; the lunula, the white crescentic
portion next to the root, its color due to diminution in size,
number, and vascularity of the papillfc, which are disposed in
longitudinal rows elsewhere in the matrix.

What are the hairs?

They are also modified epidermis, found everywhere in the

342 ESSENTIALS OF HUMAN ANATOMY.

skin, except the palms of the hands and the soles of the feet,
but vary in size. Each has a root and hair-bulb on a hair-
papilla in a hair-follicle.

The root, bulbous in form, springing from a vascular papilla
at the bottom of an involution of the epidermis and corium,
called a hair-follicle, which sometimes extends into the sub-
cutaneous cellular tissue ; into the hair-follicle open two to five
sebaceous glands ; hairs are raised by smooth muscle-fibers.
Mm. arrectores pilar urn.

The shaft consists of a central pith or medulla, a Jibrons por-
tion or cortical substance, and a cuticle of thin flattened scales ;
the medulla is commonly absent in fine hairs.

The 2^(^i"f is formed only of the cuticle and cortical portions.

Describe the sebaceous glands.

Most abundant in the scalp, face, armpits, around the anal,
nasal, and oral apertures, and in the external auditory canal ;
the largest are the Meibomian glands of the eyelids. They are
small sacculated glands, lodged in the stratum papillare of the
corium of nearly every part, except the palmar and plantar
surfaces ; the ducts usually open into the hair-follicles, but
sometimes on the general surface of the skin.

Describe the sweat-glands (coil glands).

Each has a single excretory duct and coil, situated either in
the deepest portion of the corium, or more usually in the sub-
cutaneous cellular tissue, and opening on the free surface by a
spiral duct between the papilhT3 ; the tubes are formed of an
external fibro-cellular coat, continuous with the superficial
layer of the corium, and a lining of epithelial cells continuous
with the epidermis. They are found mostly in the palms and
soles.

What are their estimated number and area ?

Nearly two and a half millions, forming an evaporating area
of about eight square inches.

The Organs of Taste.

Where does the sense of taste reside?

In the mucous membrane of the dorsum and sides of the
tongue, upper portion of the pharynx, soft palate, and fauces.

THE ORGANS OF SMELL. 343

Are there any special taste-organs?

Certain taste-buds, flask-like bodies, are supposed to com-
municate with special nerves of taste ; no such continuity
has been positively demonstrated. The taste-buds con-
sist of spindle-shaped, flattened sustentacnlar cells externally ;
the central gustatory cells have a bulging body and two
processes, the inner may be continuous with a nerve-fibril, the
outer passes to a gustatory pore on the mucous surface and ends
in a cilium, taste-hair ; these bodies are found in the circum-
vallate and fungiform papilloe, at the sides of the base of the
tongue, anterior surface of the soft palate, posterior surface of
the epiglottis, anterior surface of the anterior pillar of the
fauces. Special nerves of taste are probably the glossopharyngeal
by (1) lingual branches from the posterior third and by (2)
the chorda tympani, which communicates with this pair from
the anterior two-thirds.

The Organs of Smell.

Where does the sense of smell reside ?

In the mucous membrane lining the upper portion of the
nasal fossae, where the olfactory nerve-filament s are distributed.

Describe the nasal mucous membrane.

It is also called the Schneiderian or pituitary membrane,
and is continuous with that of the pharynx, Eustachian tube,
tympanum, and mastoid cells, and with that of the accessory
nasal cavities, the frontal, ethmoidal, and sphenoidal sinuses
and antrum ; also through the lachrymo-nasal duct with the
conjunctiva. Its epithelium is squamous below in the vestibule,
in the respiratory region ciliated and columnar, in the olfactory
columnar ; it contains numerous mucous glands ; above, certain
nucleated bodies arc found, the olfactory cells of Schvltze, with
two processes, one running between the epithelial cells to the
free surface, the other inward, to connect with a terminal nerve-
fiber.
What vessels supply the exterior of the nose ?

La/rr(dis nasi, from tlu; lacial to the ahc of the nose; the
Artery of the septum., from tin; superior coronary ; the
Nasal br<rnr.hes of the ophthalmic and infraorbital to the
dorsum and sides of the nose ; the

Veins terminate in the facial and ophthalmic.

344

ESSENTIALS OF HUMAN ANATOMY,

What are the vessels of the nasal fossae?

Anterior and jxjstcn'or cflunoidiU IVoiii the ophthalmic to the
ethmoidal cells, frontal sinuses, and roof; the

Spheno-palatiue and a twig of the mnall ineidngeal from the

Fig. 135.— The sphenopalatine ganglion and its branches ; the nerve-supply
of the left nasal fossa (Leidy).

internal maxillary to the membrane over the spongy bones,

meatuses, and septum ; the

Alveolar from the internal maxillary to the antrum ; the
Veins usually accompany the arteries, terminating in the

facial and ophthalmic veins, and in the cranial sinuses.

What nerves supply the exterior of the nose ?

Branches of the facial^ infraorhital, infratrochlear^ and nasal
branch of the ophthalmic.

Describe the nerve-supply of the nasal fossae (Fig. 135).

The olfactory^ is distributed to the mucous membrane over
the upper third of the septum and superior spongy bones ; the

Nasal branch of the ophthalmic'^ supplies the upper anterior
part of the septum and outer wall ; then it emerges to the skin
of the ala.

Anterior dental branch of the superior maxillary supplies the
inferior turbinated bone and inferior meatus : the

THE EYE. 345

Spheiw-palntine gmiglion^, by the nam-jialatine branch '', sup-
plies the middle of the septum ; by the anterior j^a^ufine, the
middle and inferior spongy bones.

The Vklhui^^ supplies the upper back part of the septum and
superior spongy bones, parts to which are also distributed the
upper anterior nasal branches of the spheno-palatine ganglion ^

(For the bones forming the nasal fossae, see p. 66.)

The Eye.

Describe the eyeball.

It is a spherical organ, with the segment of a smaller trans-
parent sphere, the cornea, forming its anterior portion, lying in
the orbit in a cushion of fat, and held in position by the ocu-
lar muscles, the optic nerve, conjunctiva, and eyelids. The
following points should be studied :

The eyeball is flattened from before backward, so its trans-
verse diameter is the longest of the three ; it measures almost
one inch (y^-^; 24.5 ram.) ; a:ntero-j)osterior diameter^ -f^^ inch
(24.0 mm.) ; vertical diameter^ -f^ inch (23.5 mm.).

Anterior and posterior jwles, the centers respectively of the
cornea and the fundus oculi.

Axes o/ei/ehalls, or ocular axes which pass through the poles
of each eye and are nearly parallel, not corresponding to the
axes of tlic orhits, which diverge.

Visual axis passes from the yellow spot through the center
of the curvature of the refracting media, so that these axes
Q.onverge.

Nodal pointy the center of the curvature of the refracting
media.

Equatorud plane, that passing through the center of the
eyeball at right angles to the axis, dividing the globe into two
segments, an anterior and a posterior hemisphere.

E(pmtor^ the line where the above-mentioned plane cuts the
surface of the eyeball.

Meridional jdanes, planes coinciding with the ocular axis.

Meridians, the lines where the meridional planes cut the sur-
face of the eyeball.

What is the capsule of Tenon?

Tlie tunica vaginalis ocvli, and consists of a thin membranous
sac isolating the eyeball jhhI allowing free movement, arising
from the optic foramen behind to become lost upon the scler-

346

ESSENTIALS OF HUMAN ANATOMY.

otic and conjunctiva in front, having a visceral layer for tWO-
thirds of the globe, a parietal layer lining the fatty cushion in
which the eye rests, both layers being lined by flattened endo-
thelial cells : the two layers enclose a lymph-space, sjyace of
Tenon, into which open the lymphatics of the sclerotic, lymph-
space of the sheath of the optic nerve, and the perichoroidal
space. The straight and oblique ocular muscles pierce it and
receive sheaths from it ; it is strengthened by elastic and fibrous
bands. Below and in front of the inferior rectus a strengthen-
ing band of fibrous tissue runs from the lacrimal to the malar
bone like a sling, ligamentum suspenson'um oculi.

What are the tunics or coats of the eye (Fig. 136)?

The sclerotic and cornea^ the most external, protective tunic.

sCLrROTir

CHOaotO
RETINA

HYALOrO KEMERANC

CILIA rv mitrssts

CIRCULAR SINUS
CAMAL or PETIT

Fig. 136.— Section of the eyeball.

The choroid, iris, and ciliary processes, the middle or vascular
tunic.

The retina, the innermost, nervous tunic.

What are the humors of the eye ?

The refracting media are three in number, viz.

The aqueous, filling the anterior chamber ;

The crystalline, or crystalline lens and capsule;

The vitreous, filling the posterior four-fifths of the globe.

THE EYE. 347

Describe the sclerotic.

It is a firm, unyielding fibrous membrane, maintaining the
form of the posterior five-sixths of the globe, thicker behind
than in front, with a smooth white external surface except where
tendons are attached, covered in front by the conjunctival
membrane, and having an inner rough brown-stained surface,
lamina fnsca. Posteriorly and to the nasal side it is pierced by
the optic nerve with whose sheath it is continuous, the sclerotic
at this point forming a thin

Lamina cribrosa^ through whose openings the nerve-filaments
pass, the most central orifice, called the poms opticus, transmit-
ting the arteria centralis retinaj. Surrounding the cribriform
lamella are numerous small openings for the ciliary vessels and
nerves ; four venae vorticosae emerge from it, and the anterior
ciliary vessels pierce it near the corneal border. The sclerotic
is formed of white fibrous tissue, mingled with fine elastic fibers
and fusiform nucleated cells. The following should be noted :

Thickness, 2V inch posteriorly (1. mm.), ^L- inch anteriorly
(0.4 mm.), about 6 mm. from the cornea.

Lamina fasca, the pigmented tissue connecting the sclerotic
with the choroid by fine threads which traverse a lymph-space.

Siihconjuncfival tissue, loose areolar tissue binding the con-
junctiva to the sclerotic ; the

Arteries are few, coming from the ciliary, and forming a
coarse network ; the

Anterior vascular zone, surrounding the cornea, is formed by
the subconjunctival branches of the anterior ciliary vessels;
the existence of

Nerves is very doubtful.

Describe the cornea.

It is the transparent, projecting, anterior sixth of the exter-
nal tunic. Tt is not quite circular, being a little broader iti the
transverse than in the vertical diameter, and is set in the sclerotic
somewhat like a watch-crystal in its case ; its thickness, one-
thirty-second of an inch to one-twenty-second of an inch, is
nearly the same throughout except toward the outer margin,
where it is thinner ; it is non-vascul<ir, the capillary vessels end-
ing in loo[)S at its circumference ; the nerves are numerous, from
twenty-four to forty-five, and an; d(;riv(Ml from the ciliary and
form the subepithelial and intraepitJielial plexuses.

348 ESSENTIALS OF HUMAN ANATOMY.

Describe the structure of the cornea.

It consists, from without inward, of the following five layers :

Layer of anterior epitheliimi, deepest cells columnar, next
polyhedral, most superficial several layers of scaly cells; the

Anterior limiting memhrane, membrane of Boioman^ 2tVo
inch (0.01 mm.) to jyVo ^'^^^ (0.02 mm.) thick, forming a thin,
firm, elastic layer consisting of extremely closely interwoven
fibrils similar to those of corneal tissue proper, but with no cor-
neal corpuscles ; it differs wholly from the posterior elastic lamina.

The suhstance j^roper is fibrous, tough, unyielding, contin-
uous with the sclerotic and composed of sixty superimposed,
flattened lamella3 made up of fibrillar connective tissue con-
tinuous with fibers of tl>e sclerotic ; the layers are held together
by a cement-substance in which are corneal spaces^ stellate in
form, communicating with adjacent spaces by processes, each
space containing a similarly shaped but smaller corneal cor-
puscle which does not entirely fill it ; the

Posterior elastic lamina (ineinhrane of Descemet or Demours)
is a structureless, elastic, brittle, extremely thin membrane, not
rendered opaque by water, alcohol, or acids; its chief pecu-
liarity is the tendency to roll upon itself with the attached
surface innermost, when separated from the cornea proper ; at
its circumference it breaks up into bundles of fibers forming
the liyamcntnm pectinatum Jridis, and leaving little intervals
or spaces between the bundles ; the

Posterior endothelial layer is a single layer of polygonal,
transparent, nucleated cells, like those lining other serous
cavities.

Describe the choroid (Fig. 137).

It is a thin, dark-brown, vascular membrane investing the
posterior five-sixths of the globe, terminating in front at the
ciliary muscle, there bending inward to form the ciliary proc-
esses ; externally it is loosely connected by a non-vascular
elastic layer, the lamina snpraclioroidea, with the lamina fusca
of the sclerotic ; each has an endothelial coat, thus forming a
lymph-space.

Choroid proper consists of two layers; the external layer is
formed of the larger branches of the ciliary arteries and the
venae vorticosae^ interspersed with stellate pigment-cells, by
the union of whose processes a delicate network is formed.

THE EYE. 349

Internal layer, tunica Rut/schiana, or choriocapillaris, con-
sists of a fine capillary plexus formed by the short ciliary ves-
sels, which is separated from the pigmentary layers of the
retina by the

Lamina vitrea, membrane of Bruch, a thin, glassy layer.

Between the two layers of the choroid proper is a thin bound-
ary zone of fibers, tapetum Jibrosum, producing a metallic luster.

The arteriefi of the choroid are the short, posterior, ciliary,
and the recurrent branches from the long posterior and the
anterior ciliary.

The veins form four or five vense vorficosse (Fig. 137), which
pierce the sclerotic midway between the corneal margin and
the entrance of the optic nerve.

The nerves are the long and short ciliary nerves.

What are the ciliary processes?

Sixty to eighty folds form a circle by the plaiting and folding
of the choroid at its anterior margin, which are received between
the corresponding folds of the suspensory ligament of the lens;
they consist of large and small processes, irregularly alternat-
ing ; the former are about one-tenth of an inch long. They
contain ciliary glands.

What is the ciliary body ?

It is that portion of the middle tunic between the choroid
and the iris formed of the ciliary muscle and ciliary processes.

Describe the ciliary muscle^.

A grayish triangular band of unstriped muscular fibers about
one-eighth of an inch broad, thickest in front, thinnest behind,
consisting of radiating and circular fibers, the former the more
numerous, arising from near the sclero-corneal junction to pass
backward to the choroid opposite the ciliary processes ; the
latter are internal, and pursue a circular course around the in-
sertion of the iris; they are called the circular ciliary muscle,
and were formerly described as the ciliary ligament.

Describe the circulus arteriosus major and minor.

The former is an anastomotic ring formed by the long ciliary
arteries at the outer margin of the iris ; the latter, a second
anastomotic circle, is formed by transverse ofisets from ,the con-
verging branches passing forward to the pupil from the circulus
major.

350 ESSENTIALS OF HUMAN ANATOMY.

Describe the iris<= (Fig. 137).

It is a thin, circular, perforated, contractile curtain, suspended
behind the cornea in tlic aqueous humor in front of the crys-
talline lens, forming the anterior portion of the middle ocular
tunic. It is formed of radiating and circular muscular fibers,
and of a fibrous stroma. AnteriorJij it is covered by a layer
of polyhedral cells resting on a fine hascmcnt-memhrane, being
continuous with the membrane of Descemet ; the posterior
sur/ice is pigmented epithelium.

Pujjil, the nearly central opening in the iris placed a little
to the nasal side of the center; diameter ranges from 1 mm. to
8 mm.

Ligamentum pectinatuni iridis,a, reticular tissue, connecting

Fig. 137.— The choroid and iris.

the iris with the cornea, derived from the membrane of Des-
cemet, which sends fibrous prolongations to the iris and sclero-
corneal junction.

Spaces of Fontaiia, the intervals between the reticulated
fibers of the ligamentum pectinatum at the outer angle of the
anterior chamber, which communicate with a larger space in
the sclerotic close to the sclero-corneal junction and with the
anterior chamber.

Canal of Schlemm, or sinus circularis iridis, lined with en-
dothelium, a venous sinus, containing two or three plexiforra
veins receiving blood from the sclerotic and ciliary plexuses
and communicating with the anterior ciliary veins.

Uvea, a layer of purplish-hued pigment-cells on the posterior

THE EYE. 351

surface of tlie iris continuous with the retinal pigment-layer of
the ciliary processes.

Spliincter pupillst^ the narrow hand of circular muscular
fibers surrounding the pupil on its posterior surface, one-fiftieth
of an inch wide (0.5 mm.), supplied by the third nerve through
the ophthalmic ganglion

Dilator pupillx^ consisting of the radiating muscular fibers
converging from the circumference of the iris toward the
pupillary margin, where they blend with the circular fibers ; it
is supplied by sympathetic fibers from the ophthalmic gan-
glion.

Memhrana pnpiJlaris^ a delicate, transparent, vascular mem-
brane which occluded the pupil in the fetus, usually disap-
pearing about the eighth fetal month, but occasionally per-
sisting ; it is nourished by many small vessels continued from
the margin of the iris to those on the front part of the lens-
capsule.

Arteries are branches of the long and anterior ciliary form-
ing the circulus iridis major and minor (see p. 194).

Veins empty into those of the ciliary processes and into the
anterior and long ciliary veins, and communicate with the canal
of Schlemm.

Nerves are branches of the ciliary ganglion, from the nasal
branch of the ophthalmic division of the fifth, the third nerve
going to the sphincter pupillae (circular fibers), the sympathetic
to the dilator pupillae (radiating fibers), and the fifth supplying
common sensation.

What is the retina ?

The innermost ocular tunic, forming a delicate, grayish,
transparent, nervous membrane, pars optica retinae^ ending near
the ciliary body by a ragged margin, the ora serrata ; its
fibrous stroma, covered by the pigment-layer, passes forward to
the ciliary margin of the iris as the pars ciliaris retinse ; behind
the iris is the jxns iridica retinse.

Macula lutea, or yellow spot of Sommerhig, is an elliptical,
elevated spot exactly in the center of the retina posteriorly,
which corresponds ttt the axis of the eye ; here vision is most
perfect, the retina being thin and crowded with nerve-elements,
but destitute of rods and the nerve-fiber layer ; the diameter
is 1 to 2 mm.

352

ESSENTIALS OF HUMAN ANATOMY.

Fovea centralis is a minute central depression at the summit
of the yellow spot ; the diameter is 0.2 mm. to 0.4 mm.

Porus opticua is a disk at the point of entrance of the optic
nerve, centrally pierced by the arteria centralis retinae, lying
about jig- inch (3 mm.) to the inner side of the yellow spot
and 1 mm. below its level ; it is the only portion of the retina
where the sense of vision is wanting, the hlind spcA ; the margin
of the disk is elevated, called the colh'cidus nervi optici.

Pars cilians retinei: consists of the fibrous and pigmented por-
tions of the retina, destitute of nerve-elements, continued over
the ciliary processes from the ora serrata to the iris ; the

Arteries of the retina spring from the arteria centralis retinae,
a branch of the ophthalmic, which after piercing the optic

nerve divides into four or five
branches, which soon enter the
nervous layer of the retina to
form a fine capillary plexus not
extending beyond the inner nu-
clear layer ; no vessels exist in
the fovea centralis, very few in
the macula lutea ; there are no
anastomoses.

Describe the structure of the
retina.

It is exceedingly complex,
being composed from within out-
ward of ten layers, or properly
eight, two being boundary lines
(Fig.' 138).

Membrana limitans interna^ a
transparent membrane formed of
retinal connective tissue, lying in
contact with the hyaloid mem-
brane of the vitreous humor.

1. Xerve-Jiher layer, composed
of continuations of optic fibers
deprived of their medullary
sheaths, forming radiating bun-
FiG. 138.-The^l^ayers^of the rcti.ia ^j^^ ^^ plexuses joining the next

layer.
2. Ganglionic layer, a single layer of large ganglion-cells,

THE EYE. 353

except at the macula lutea, where there are several layers ; they
have one process prolonged into the fibrous layer, becoming con-
tinuous with a nerve-fibril, and one or more extending into the
inner molecular layer, or (according to some) passing through
it to terminate in the nuclear layer.

8. Inner molecnlar or reticular layer ^ made up of a reticulum
of fibrils, mingled with processes of the ganglion-cells and those
of the next layer, containing in the interstices minute clear
granules.

4. Inner nuclear layer^ containing (1) bipolar cells with oval
nuclei, one process passing to the inner molecular layer,
believed to become continuous with the processes of the gan-
glion-cells, and another passing into the outer molecular layer,
there bifurcating and (according to some) communicating with
rod and cone fibers ; (2) nucleated cells without branches ;
(3) cells connected with the fibers of Miiller.

5. Outer molecular layer is thinner, resembles the inner molec-
ular layer, but contains branched stellate cells — probably
ganglion-cells.

6. Outer nuclear layer consists of (1) rod-granules^ trans-
versely striated cells, with an external fine process connected
with a single rod of Jacob's membrane, and an internal pro-
longation which enlarges, then breaks iq) into minute fibrils
entering the outer molecular layer; and (2) cone-granules,
closely connected with the cones of Jacob's membrane, with a
thick process passing inward, becoming bulbous (cone-foot) and
terminating by numerous fibrillge, which enter the outer molec-
ular layer.

External limiting memhrane, a membrane formed of retinal
connective tissue, perforated by numerous openings.

7. JacoVs memhrane or rods and cones, composed of rods ar-
ranged perpendicularly to the surface, each composed of an outer
and an inner portion joined by cement-substance ; and cones,
with apices directed toward the choroid, formed of two portions,
and like the rods having their outer segments transversely
striated ; this is probably the perceptive layer of the retina.

8. Pigmentary layer, formerly considered a part of the cho-
roid, consisting of a single layer of hexagonal, pigmented epi-
thelial cells.

The connective tissue uniting the layers is a fenestrated,
sponge-like structure, the membrane of MUller,
23

354 ESSENTIALS OF HUMAN ANATOMY.

The Humors.

What is the aqueous humor?

A small amount of clear alkaline fluid composed of water,
96.7 per cent. ; albumin, U.l ; sodium chlorid and extractive,
3.2 ; filling the anterior and posterior aqueous chambers of
the eye.

What are the anterior and the posterior aqueous chamhers ?

The anterior chamber is a space filled with aqueous humor
bounded in front by the cornea, behind by the front of the iris,
and communicating through the pupil with the

Posterior chamber, also tilled with aqueous humor ; it is only
a narrow chink between the peripheral portion of the iris, the
suspensory ligament, and the ciliary processes ; the chambers
are separate in the fetus.

Describe the vitreous body.

This forms about four-fifths of the entire globe, is trans-
parent, of the consistence of thin jelly, composed of water, 98.5
per cent., a few salts, and a trace of albumin, and is enclosed
everywhere in a delicate hyaloid membrane, beneath which are
small, granular, ameboid cells ; it possesses neither vessels nor
nerves, and has the fonsa imtcllaris in front, where the crystal-
line lens reposes. Running from the entrance of the optic
nerve to the posterior surface of the crystalline lens is the
canal of StiUinr/, or liyaloid canal, filled with fluid and lined
with hyaloid membrane ; it once carried a fetal artery.

Describe the crystalline lens with its ligaments.

It is a transparent double convex body, more convex pos-
teriorly than in front, enclosed in a capsule, and is lodged in a
depression of the hyaloid membrane, where it is retained by its
suspensory ligament. It lies immediately behind the pupil
surrounded and slightly overlapped by the ciliary processes,
measuring about one-third of an inch transversely by one-
fourth of an inch antero-posteriorly, and is composed of water,
albuminous matter, fat, and cholesterin. The center of each
surface is the pole; the surfaces meet in a rounded border,
the equator.

Capsule is transparent, very elastic, and brittle, measuring
2^L_ inch in front, g-gVo ^^^^^ behind, and is attached anteriorly

THE HUMORS. 355

to the lens by a single layer of polygonal cells ; posteriorly be-
tween the lens and the capsule this layer is lacking ; here fluid
may collect post mortem, liquor Moryagni.

At the ora serrata the hyaloid membrane splits into two
layers ; one passes behind the lens in front of the vitreous
humor, which is completely invested ; the other layer continues
over the ciliary body and pars ciliaris retinae, and is called the
zonula of Zinu ; its free part extends from the ciliary body to
the leUvS-capsule, and is called the suspensori/ Ugrnnent of the
lens.

Due to plications of the ciliary body over which the zonula
is reflected there are two sets of fibers in the suspensory liga-
ment; one comes from the zonula as it lies on the summif.s of
the ciliary processes, and goes to the periphery of the lens and
adjoining part of its posterior capsule ; the set arising from the
vallet/s between the ciliary processes passes to the anterior cap-
sule of the lens. These sets partially cross each other at their
origins.

Canal of Petit, triangular on section, passes around the cir-
cumference of the lens, bounded in front by anterior fibers of
the suspensory ligament, behind by the hyaloid membrane,
mesially by the capsule of the lens ; when inflated it becomes
sacculated.

What is the structure of the crystalline lens ?

It is formed of numerous laminae, composed of six-sided
fi^^^'^ 5 0^0 0 ^^^^ broad (0.005 mm.), with serrated margins,
those of contiguous fibers accurately fitting one another ; the
lens is also divisible into three triangular segments with their
bases outward. Each surface shows three r«y.s of a star at
angles of 120°. The central harder portion is called the nucleus^
the peripheral portions the cortex ; it possesses neither vessels
nor nerves.

Describe the muscles of the eyeball (Fig. 139).

Rectus superior^: origin, upper margin of the optic foramen
and sheath of the optic nerve ; insertion, sclerotic coat three or
four lines from the cornea ; action, turns the eyeball upward
and inward ; nn-ve, third cranial.

Rectus inferior ^ : origin, ligament of Zinn ; insertion, sclerotic,
three or four lines from the cornea ; action, turns the eye down-
ward and inward ; nerve, third cranial.

356

ESSENTIALS OF HUMAN ANATOMY.

Rectus internus : origin, ligament of Zinn at the inner side of
the optic foramen ; insertion, the sclerotic, three or four lines
from the cornea ; action, turns the eye inward ; nerve, third
cranial.

Rectus externus^: origin, by two heads, the upper ^ from the
outer margin of the optic foramen, the lower ^ from the liga-
ment of Zinn, and a pointed bony process at the lower margin of
the sphenoidal fissure ; insertion, sclerotic, as the other recti ;
action, turns the eye outward; nerve, sixth cranial (abducens) ;
between the two heads pass the ophthalmic vein, the third,
the nasal branch of the fifth, and the sixth cranial nerves.

Obliquus superior ^ : origin, one line above the inner margin
of the optic foramen, terminating in a rounded tendon which
plays through a fibro-cartilaginous ring or pulley ^ beneath the
internal angular process of the frontal bone, whence it passes
beneath the superior rectus ; insertion, sclerotic between the
superior and the external recti, midway between the cornea
and the entrance of the optic nerve ; action, rotates the eye on

Fig. 139.— Muscles of the right orbit (Leidy).

its antero-posterior axis and corrects inward deviation of the
inferior rectus ; nerve, fourth cranial (patheticus).

Obliquiis inferior^": origin, orbital plate of the superior max-

THE HUMORS. 357

ilia ; insertion, sclerotic between the superior and the external
recti ; action, rotates the eyeball outward and corrects inward
rotation of the superior rectus ; nerve, third cranial.
(For the muscles of the lids see p. 142.)

Recapitulate the nerve-supply of the ocular muscles.

Third cranial, or motor oculi, supplies the superior, internal,
and inferior recti, and the inferior oblique muscles.

Fourth cranial, or patheticiis, supplies the superior oblique
muscle.

Sixth cranial, or ahducens, supplies the external rectus
muscle.

Describe the vascular supply of the eyeball and its appendages.

(All branches of the vessels not supplying these parts iiill
he omitted, having been already described on pages 191 to 194.)

Ophthalmic, arising from the cavernous portion of the inter-
nal carotid, entering the orbit by the optic foramen, giving off
the

Lacrimal to the lacrimal gland, conjunctiva, and upper eye-
lid, and inosculating with the palpebral arteries.

Supraorhit(d supplies the levator palpebrse and superior
rectus muscles.

Superior and inferior palpchral supply the eyelids.

Nasal supplies the lacrimal sac.

Short ciliary, six to twelve in number, penetrate the sclerotic
around the optic nerve entrance to supply the choroid and
ciliary processes.

Long ciliary, two in number, penetrate the sclerotic, pass
forward between it and the choroid to supply the iris, forming
the circnlm iridis major near the ciliary margin, and the cir-
cidns iridis minor near the margin of the pupil.

Anterior ciliary, six to eight, spring from the muscular
branches, perforate the sclerotic, and join the circulus iridis
major.

Arteria centralis retinse obliquely traverses the optic nerve
to be distributed to the retina.

Mnscnlar branches, one superior, one inferior, to the ocular
muscles.

Infraorhital, from the internal maxillary, supplies the inferior
rectus and inferior oblique muscles and lacrimal gland.

358 ESSENTIALS OF HUMAN ANATOMY.

What are the chief lymph-spaces of the eyeball ?

Anterior and poderiur aqueous chambers^ spaces of Fontana,
Schlemnis and Fetit's canals, If/mph-spaces of the cornea and
iris, hyaloid canal, perivascular canals of the retina, jierichoroidal
space between the choroid and the sclerotic, cavity of the cap-
sule of Tenon between the eyeball and the capsule, supravaginal
and intervaginal spaces of the optic nerve.

What veins return the blood from the eye ?

The superior and inferior ophthalmic, emptying usually by a
short common trunk into the cavernous sinus ; they also freely
anastomose with the angular vein of the face.

Name the nerves of the eye.

Optic or second craniid, nerve of the special sense of sight.

Motor nerves, the third, fourth, and sixth cranial.

The ophthalmic division of the fifth supplies general sensa-
tion by the

Lacrimal, to the same named gland, conjunctiva, and skin of
the upper eyelid ; also the following branches : frontal, which
gives the supratrochlear, and supraorhital, nasal with its gan-
glionic, long cdiary, and infratrochlear branches. Orbital or
temporo-malar nerve from the second division of the fifth also
enters the orbit.

The sympathetic arises from the cavernous and carotid plexus,
receiving communicating filaments indirectly from the spinal
nerves, and sending branches to the third, fourth, fifth, and
sixth nerves ; the dilator fibers (radiating) of the iris, ciliary
ganglion, muscles of the orbit and lids, with the walls of the
arteries, receive their sympathetic nerve-supply from this
source ; the

Short ciliary, numbering six or eight, arise from the ciliary
ganglion, subdivide into twelve to twenty fine filaments and
pierce the sclerotic posteriorly in two bundles, to ramify in the
sheath of the optic nerve, choroid, ciliary muscle, iris, and
cornea.

Ascending branches of the spheno-pahttine (^MecheVs) ganglion,
reaching the orbit by the spheno-maxillary fissure, usually
supply the periosteum, send a twig to the optic nerve (Arnold),
to the sixth nerve (Bock), to the ciliary ganglion (Tiedemann).

THE APPENDAGES OF THE EYE. 359

Give a brief description of the optic tracts.

The deep origins of the nerve-fibers of these tracts are the
optic thalami, corpora genicuhita, upper pair of the corpora
quadrigemina; which, forming two flattened bands, wind around
the crura cerebri, to which they are sHghtly attached, as well
as to the lamina cinerea and tuber cinereum, and joining in
front of the latter they form the optic commissure (see pages
241 and 242 for illustration and more elaborate description).

What are the origin and course of the optic nerves ?

They arise on either side from the optic commissure ; each
passes into the orbit through the optic foramen with the cen-
tral artery of the retina, which pierces it, and enters the eyeball
through the lamina cribrosa yL inch (3 mm.) to the nasal side
of the yellow spot and 1 mm. below it ; these nerves are sur-
rounded with a sheath derived from the dura mater, between
which and the nerve is a lymph-space communicating with
the subarachnoid and subdural spaces.

The Appendages of the Eye.

(Tutamina Oculi.)

Name these.

Eyebrows^ or mpercilia^ L(tcrim(d gJand^ and diicfs,
Eyelids^ or jjrdpebr^, Lacrimal sac and caiialiculi,

Conjunctiva'^, a mucous Nasal duct.
membrane,

What are the eyebrows ?

The arched eminences of skin surmounting the upper mar-
gins of the orbits on each side, from which grow several rows
of short, obliquely placed hairs ; by the attached muscles the
eyebrows can partially shut off light from the eyes.

What are the eyelids ?

Two movable; curtains protecting by their closure the eyes
from injury ; the upper lid is the larger and more movable,
having its own csbivator niuscl(\ levator p^ilpchnr ; the

l^dljx'hrid Jissurc. is th(! elliptical space ])etween the margins
of the lids when opened, the internal and external angles being
called, respectively, the infrrual and tlu^ rxtrruai cauflnts, the

360 ESSENTIALS OF HUMAN ANATOMY.

former being prolonged inward, leaving a triangular space be-
tween the lids, the htaia lacrimalis, at the commencement of
which is a small elevation on each lid, the lacrimal jxqnlla^,
whose, summit is pierced by a minute opening, the pinic^wm
lacrimale^, the commencement of the lacrimal canal.

What structures form the eyelids ?

Externally the skin, beneath which is much loose areolar
tissue, separating it from the fibers of the orhicidaris pa/^>e-
hraruin muscle. The lids retain their shape by means of the
so-called tarsal cartilages — in reality dense connective tissue
icithout cartilage-cells — that for the upper lid being half-oval
and the larger, that for the lower lid narrower ; these struct-
ures are connected at their orbital margins with the circumfer-
ence of the orbit by fibrous membranes, the tarsal ligaments ; the
internal palpehral {tarsal) ligament, or tendo ocvli, passes from
the inner angle of each to the nasal process of the superior
maxilla ; the external palpehralligament passes to the malar bone.

Embedded in the ocular surface of the cartilages are sebace-
ous glands, the Meihomian^ discharging their secretion upon the
free edge of the lids, preventing their adhesion ; they number
thirty or forty in the upper lid, are fewer in the lower lid.

Attached to the free margins of the lids is a double or triple
row of stifi" hairs, curved in each lid so that their convexities
meet, preventing interlacing; these are the cilia., or eyelashes;
just within this line is a row of modified sweat-glands, the
glands rjf Moll.

The arteries are two internal palpebrals from the ophthalmic,
two external palpebrals from the lacrimal, the transverse facial,
and the superficial temporal.

The nerves are the third, seventh, and the sympathetic to the
muscles, the ophthalmic branch of the fifth to the skin and the
conjunctiva.

Describe the conjunctiva.

It is a mucous membrane lining the inner surfaces of the
eyelids and reflected thence, _/o?vnx conjuneficae. upon the ante-
rior segment of the sclerotic, its epithelial layer passing over
the cornea.

T\i& palpehral conjunctiva is thick, opaque, vascular, and cov-
ered with papillae, containing numerous glands; at the inner

THE APPENDAGES OF THE EYE. 361

angle of the eye it forms a vertical semilunar fold, the plica
semilunar^*. The folds formed by the passage of the conjunc-
tiva from the lids to the eyeball are called the superior and in-
ferior p)a^pebral folds, the former being the deeper ; they con-
tain numerous convoluted mucous glands, some of which
resemble lymphoid follicles.

The ocular conjunctiva is thin, transparent, possesses few
vessels in health, and is loosely attached to the globe by the
subconjunctival areolar tissue.

The corneal conjunctiva consists only of epithelium.

What is the caruncula lacrimalis^ (Fig. 141)?

It is a small, conical, reddish body, at the inner canthus,
occupying the space called the lacus lacrimalis, and is formed
of a group of follicles, sebaceous and sweat-glands, covered
with skin ; from the caruncle project a few slender hairs.

Describe the lacrimal apparatus.

It consists of the lacrimal gland with its ducts, the canali-
culi, the lacrimal sac. and the nasal duct. The

Lacrimal ghuuP (Fig. 140) is an oval, compound racemose
gland of the size and shape of an almond, lodged in a depres-
sion at the upper, outer portion of the orbit, its concave under
surface resting upon the globe of the eye, the conjunctiva,
superior and external recti muscles intervening ; it is held in
contact with the orbital periosteum by a few fibrous bands ; it
has two parts, the smaller one called the inferior lacrimal
gland. It has never more than twelve

Ducts'^, opening by minute orifices in a row on the upper and
outer part of the conjunctival fornix.

Tears are taken up by the puncta, thence passing through
the canaliculi into the lacrimal sac and nasal duct, thus reach-
ing the inferior meatus of the nose.

Describe the canaliculi.

They are two minute canals^ about one-half a line in diam-
eter, commencing at the puncta ; the superior passing upward,
then bending acutely to pass inward to the lacrimal sac ; the
inferior passing downward, then upward and inward ; they are
lined with mucous membrane continuous with the conjunctiva,
and are one-third of an inch long (8 to 9 mm.).

362

ESSENTIALS OF HUMAN ANATOMY.

What is the lacrimal sac- iFig. 141)?

It is the tlattouL'cl. uvoidal, sacciform dilatation of the upper
part of the nasal duct, lodged in the groove formed by the lac-
rimal bone and nasal process of the superior maxillary ; its
walls are formed of tibrous tissue covered internally by the

Fig. 140. — The lacrimal gland and
Meibomian glands, seen from the
inner surface of the eyelids (Leidy).

Fig. 141.— The lacrimal apparatus,
left side (Leidy).

tensor tarsi muscle, and in front is the tendo oculi attached to
the ridge of the lacrimal bone. When distended it is 15 mm.
long and 5 or 6 mm. wide.

Describe the nasal duct\

It is a membranous canal about three-fourths of an inch long
(12 to 24 mm.), extending from the termination of the lacri-
mal sac through the osseous nasal duct to the inferior meatus
of the nose, passing in a direction downward, backward, and
slightly outward, its lumen being narrowest about the mid-
point : externally it is composed of fibro-areolar tissue ; inter-
nally, of mucous membrane continuous with that of the nose
and lacrimal sac : the epithelial coating of the sac and duct
is columnar and ciliated only in spots ; squamous in the cana-
liculi.

What is the valve of Hasner?

An imperfect valve of mucous membrane guarding the some-
what expanded terminal opening of the duct into the inferior
meatus of the nose : other valvular folds are less constant.

THE EXTERNAL EAR. 363

The Ear.

Where is the auditory apparatus lodged?

In the petrous, mastoid, and tympanic portions of the tem-
poral bone.

Enumerate the divisions.

m , 7 • • f Auricle, or pinna.

ine ex^erwrt/ ear, compnsinor . { rr ^ i i-^ ?

T ^ ^ y^ tiXtemal auditory canal.

C Memhrana fympani^
CnvitU of ft/mvanum

The middle ear, or tympanum. \ Cavity of tympanum^

comprising ^ Mastoid celh^

[^ Eustachian tuhe.

^ Vestibule^
The internal ear. or lahyrinth, J Semicircular canals^

comprising | Cochlea ^

\^ Auditory nerve.

The External Ear.

What is the auricle or pinna?

Its foundation is an expanded layer of fibro-cartilage. so dis-
posed in ridges as to concentrate and direct the waves of sound
into the external auditory meatus, to which it is attached : the
cartilage is deficient at certain points where it is connected by
fibrous tissue : it is covered with perichondrium, outside of
which is thin, firmly adherent skin, containing sweat- and se-
baceous glands, and provided with short downy hairs. The
various ridges and depressions are as follows : the

Concha, the deep cavity leading into the meatus; the

Tragus, the pointed prominence in front of the concha pro-
jecting back over the meatus, bearing on its under surface tufts
of hair ; the

Antifififjus, a small tubercle opposite the tragus, separated
by a deep notch, the incisura intertragica ; the

Jlflis, the external prominent margin of tho auricle rising
near the tragus ; the

Antihelix, a parallel prominence anterior to the former,
rising below at the antitragus. bifurcating above to form the

Foss/t of the aiitihelix, a triangular depression ; the

Fossa of the helix, the narrow, curved depression between
the heli.K and the antihelix (fossa scaphoidea).

364 ESSENTIALS OF HUMAN ANATOMY.

An ear-pouif, or tubercle of Dane in, is occasionally seen on
the postero-superior margin of the helix pointing forward ;
it is constant in the human embryo, and permanent in many
monkeys.

The inferior, soft pendulous portion, formed of fat and con-
nective tissue enclosed by integument, is the lobule of the ear.

Describe the muscles of the external ear.

The attollens aurem, attrahens aurem, and retrahens aurem
have been described on page 142 ; these are extrinsic ; the in-
trinsic are the muscles of the auricle, but slightly developed in
man : their motor nerve is the facial.

Helicis major: a narrow, vertical band on the anterior border
of the helix ;

Helicis minor: an oblique band at the root of the helix from
the concha ;

Tragicus : a short, vertical band on the outer surface of the
tragus ;

Antitragicus : stretching from the outer part of the antitragus
to the lower part of the helix ; these four muscles are anterior.

Transversus auriculae : radiating from the posterior surface of
the convexity of the concha to the prominence caused by
the groove of the helix ;

Obliquus auris : a few fibers passing from the upper back
part of the concha to the convexity immediately above.

Give the vascular and nerve-supply to the auricle.

The arteries are Posterior eiuricuhir, from the external carotid.

Anterior auricular, branch of the temporal.

Auricular, branch of the occipital.
The veins accompany the corresponding arteries.
The nerves are Anricularis 7)iagnus, from the cervical plexus.

Posterior auricular, from the facial.

Auricular branch (Arnold's) of the pneumo-
gastric.

Aiiriculo-temporal, from the inferior maxil-
lary division of the fifth nerve.

Occipitalis major and minor.

What is the external auditory canal ?

It is an osseo-cartilaginous, oval, cylindrical canal, w^th its
greatest diameter vertical at the external orifice, but reversed

THE MIDDLE EAR OR TYMPANUM. 365

at the tympanic end ; it is narrowest at the middle. About
one inch long (25 mm.), it is directed obli({uely forward and
inward, and slightly curved with its convexity upward, and is
lined with thin adherent skin, containing hair-follicles and
sebaceous and ceruminous glands in its cartilaginous portion.
A narrow groove for the membrana tympani is at the inner
end, called the sulcus tympaaicus^ interrupted above by the
notch of Rivinus between the anterior and the posterior tym-
panic spines.

What are the arteries and nerves ?

The arteries are branches of the posterior auricular, internal
maxillary, and temporal.

The nerves come chiefly from the auriculo-temporal branch
of the third division of the fifth nerve and from the auricular
branch of the vagus.

The Middle Ear or Tympanum.

Describe the membrana tympani.

It forms the outer wall of the tympanum, and is an oval,
translucent membrane placed obliquely at the bottom of the
external auditory meatus, with its internal surface facing
downward, forward, and inward at an angle of 55°,with its long
axis directed downward and inward ; it inclines toward the an-
terior and lower part of the canal ; at its upper anterior border
is a white, pointed tubercle^ formed by the short process of the
malleus, while a yellowish-white stripe passing from this down-
ward and backward toward the center indicates the handle of
the malleus. During life, when illuminated, the membrana
tympani presents a triangular light spot or " cone of light^' hav-
ing its apex at the end of the malleus handle, whence it spreads
downward and forward ; a darker central portion is the mnho.,
or shadow. The upper anterior part bridging a small notch
in the bony ring to which the membrane is attached (the notch
of Rivinus), is thin, consisting of loose connective tissue, ves-
sels, and nerves, covered with skin and mucous membrane, and
has received the name of the membrana flaccida^ or Shrap-
nelVs membrane.

Of what tissues is the membrana tympani composed ?

Of the skin, which is derived from the lining of the meatus;

36G ESSENTIALS OF HUMAN ANATOMY.

of a fibrous layer, some of whose fibers radiate from near the
center to the circumference, others form a dense ring around
the attached margin ; and of mucous membrane, derived from
that lining the tympanum. The handle of the malleus passes
between the inner and the middle layers — according to von
Troltsch, it is received between the circular and the radiating
fibers of the middle coat ; an anterior and a posterior pouch
have also been described upon the external surface opening
downward. The radial fibers are slightly bowed outward, so
that between the depressed umbo and the attached border the
membrane is convex externally, due to annular fibers.

Describe the arterial supply of the membrana tympani.

The deejj auricular branch of the internal maxillary sup-
plies the external layers, forming a plexus which communicates
at the periphery with one in the mucous membrane formed
from the

Tympanic hranches of the internal maxillary and internal
carotid arteries, and by the

Tynqjanic branch of the Vidian^ from the internal maxillary,
and the

Stylo-mastoid^ from the posterior auricular.

Mention the nerves supplying the membrana tympani.

To the upper portion run filaments from the auriculo-tem-
poral branch of the fifth, to the lower portion, the auricidar
branch of the vagus, while the mucous layer is supplied by
the tympanic plexus.

The Tympanum.

Describe it.

It is an irregular cavity, measuring about one-half inch an-
tero-posteriorly, one-third inch vertically, and one-fifth inch
transversely, situated in the petrous bone, compressed from
without inward, being placed above the jugular fossa, having
the carotid canal in front, the mastoid cells behind, the external
meatus externally, and the labyrinth internally ; it communi-
cates in front with the pharynx by the Eustachian tube, and
presents for examination the following points : the

Roof, a very thin plate of bone, indicated on the cranial sur-
face by a depression on the anterior surface of the petrous
portion of the temporal bone, the tegmen tympani ; the

THE TYMPANUM. 367

Floor ^ narrow, corresponding to the jugular fossa, and pre-
senting near the inner wall a small foramen for Jacohsons
nerve ; the

Outer icall, the membrana tympani and bony ring to which
it is attached, presenting three small orifices, the

Iter chordae poster ixs, opening in the angle of the junction
between the posterior and external walls, just behind the
membrana tympani on a level with its center, for the entrance
of the chorda tympani nerve ; the

Glaserian fissure^ 'petro-tym'pamc^ just above and in front
of the bony ring, giving passage to some tympanic vessels,
the tympanic branch of the internal maxillary artery, and
lodgment of the long process of the malleus ; the

Iter chordse aiiterius, or canal of Huguier^ opening just above
the preceding, for the escape of the chorda tympani nerve ; the

Inner wall is vertical, looking directly outward, and presents
the

Fenestra ovalls or oval window, a kidney-shaped opening
leading into the vestibule, closed by the base of the stapes
with its ligament ; the

Fenestra rotunda or round im'ndow, below, at the bottom of a
funnel-shaped depression, opening into the scala tympani of
the cochlea, closed by the membrana tympani secundaria,
having mucous, fibrous, and serous layers.

Promontory, a rounded hollow eminence — the first turn of
the cochlea — situated between the oval and the round win-
dows, and presenting grooves lodging branches of the tym-
panic plexus ; the

Eminence of the aqnsedvctus Fallopii passes above the oval
window, along the inner tympanic wall, to curve behind that
opening nearly vertically downward along the posterior wall ;
the

Posterior wall presents the opening of the mastoid antrum.

Pyramid, a hollow conical projection, behind the oval win-
dow and in front of the vertical portion of the aquacductus
Fallopii, contains the stapedius muscle, whose tendon escapes
from its summit ; a minute canal communicates with the aquae-
ductus Fallopii, transmitting a twig of the facial nerve to the
stapedius muscle ; the

Ojteniny of the mastoid antrum is above the pyramid in
the attic.

368 ESSENTIALS OF HUMAN ANATOMY.

The (interior wall is wider above than below, is related to
the carotid canal, the thin bony partition being perforated
by the tympanic branch of the internal carotid artery ; it pre-
sents two openings : the

Orifice of tlie canal for the tensor tympani muscle, which is
situated above, close to the Eustachian tube, on the summit
of a small conical eminence, the processus cochlearifjrniis; the

Opening (f the Uusfachian tube is immediately below the
preceding, separated partially by a thin bony plate, the sep)tum
tubse.

What are the ossicles of the tympanum ?

Three bones forming a movable chain, passing between the
membrana tympani and the oval window (Fig. 142), called the

Malleus or hammer, consisting
of an oval head articulating with
the incus, a nech, a manubrium
or handle, affording attachment
near its root to the tensor tym-
pani muscle, a short ])Yocess, proc-
essus brevis, coming in contact with
the membrana tympani, and a
processus gracilis or long process,
}^o^ici^a.ri lodged in the Glaserian fissure,

and fastened by bony or liga-

T?r^ T.o rru nu ^*i, mentous attachment ; the
Fig. 142.— The small bones of the ^ .# i • 77

left ear; external view (enlarged) Incus or anvil, having a bocii/

(after Gray). articulating with the malleus, a

long process terminating in a rounded end, the os orbiculare,
or lenticular process, which articulates with the head of the
stapes, and a short process attached to the margin of the open-
ing into the mastoid cells ; the

Stapes or stirruj) consists of a head articulating with the os
orbiculare, a neck receiving the insertion of the stapedius mus-
cle, two branches or crura joining the oval base, which latter is
connected with the margins of the oval window by ligamentous
fibers.

Describe the ligaments of the ossicles.

The suspensory ligament of the malleus, passing between the
tympanic roof and the head of the malleus ; the anterior liga-

THE TYMPANUM, 369

ment of the mallens goes from its neck to the anterior wall near
the Glaserian fissure ; the external ligament of the malleus, fan-
shaped, converges from the margin of the notch of liivinus to
the processus brevis.

The posterior lujament of the ineiis, passing between the pos-
terior tympanic wall near the margin of the opening into the
mastoid cells and end of the short process of the incus; the
suspensor)/ ligament of the incus, descending from the tympanic
roof to the incus, near its articulation with the malleus ; the

Annular ligament of the stapes, connecting the circumference
of its base to the margins of the oval window ; the

Capsular ligaments, around the articulations between the
incus and the malleus, os orbiculare and stapes, these joints
having their surfaces coated with hyaline cartilage and being
provided with synovial membranes.

Other ligaments have been described under special names, as
accessory anterior and inferior ligaments of the malleus, and
the obturator ligament of the stapes, this latter being a mem-
brane filling up the opening between the crura of the stapes.

Describe the muscles of the tympanum.

Only two are well recognized. Sommering described four,
others have mentioned still more ; but further research proves
them to be ligamentous or fascial ; the major and minor laxator
tympani muscles are now described as ligaments of the malleus.

Tensor tympani : origin, under surface of the petrous bone, ad-
joining portion of the cartilaginous Eustachian tube, its own
osseous canal ; it makes a sharp bend outward around the end
of the processus cochleariformis ; insertion, handle of the mal-
leus near the root ; action, draws the membrana tympani in-
ward— /. e. increases tension ; nerve, by a twig to the internal
pterygoid muscle through the otic ganglion.

Stapedius: origin, from the interior of the pyramid ; insert i(m,
neck of the stapes; its tendon may contain a bony spine; ac-
tion, compresses the contents of the vestibule; it pushes the
hinder part of the base of the stapes into the vestibule and
draws the fore part from it ; nerve, filament of the facial.

Describe the arterial supply of the tympanum.

These arteries are about six in number ; two are large, and
form a vascular circle on the margin of the membrana tym-
2t

370 p:ssentials of human anatomy.

pani. The ti/mpanic hranch of the internal maxillary enters
by the (llaserian fissure and is distributed to the niembrana
tympani, joining the

Sff/I(>-ni(t.'ifoi(/, from the posterior auricular to the back part
of the tympanum and mastoid cells. This enters by the stylo-
mastoid foramen. Other small branches are the 2:>etrosaI, from
the middle meningeal, entering through the hiatus Fallopii ;
the

Tj/mpanic, from the internal carotid, perforating the thin
bony wall ; the

Tympanic hranch of tlic Vidian, from the internal maxillary
and a

Branch from the ascending pharyngeal, both by the Eusta-
chian tube.

What nerves supply the tympanum?

The tympanic hranch of the gl<n:i>(>-p>]air}jn(jcal (Jacobson's
nerve), which pierces the floor of the tympanum, and aids in
forming the tympanic ph-xus, which supplies the fenestras,
mucous membrane, and Eustachian tube ; the

Tympanic hranch of the facial, supplying the stapedius
muscle ; the

Branch from the otic ganglion, supplying the tensor tympani
muscle.

(The chorda tympani from the facial, passing into the tym-
panum by the iter chordae posterius, emerging by the iter
chordae anterius, arching across the cavity between the handle
of the malleus and the long process of the incus ; it is covered
with mucous membrane and gives off no branches.)

Describe the formation of the tympanic plexus.

The plexus occupies shallow grooves on the inner wall of
the middle ear, especially on the promontory, and is formed by
(1) Jacohsons nerve from the petrosal ganglion of the glosso-
pharyngeal ; (2) the small deep petrosal (carotico-tympanicns
snperior^ runs in the processus cochleariformis, enters the
foramen lacerum (middle lacerated), and joins the sympathetic
plexus on the carotid artery ; (3) a branch joins the great
superficial petrosal nerve in the hiatus Fallopii ; (4) the small
superficial petrosal receives a filament from the geniculate gan-
glion of the facial and passes to the otic ganglion ; (5) the

THE TYMPANUM. 371

carotico-tympanicus inferior is a sympathetic twig (or twigs)
passing up from the carotid plexus to the tympanic plexus.

Describe the Eustachian tube.

It is about one and one-half inches (36 mm.) long, passing
downward at an angle of 30° from the horizontal, forward and
inward at an angle of 45°, the passage by which the air in the
middle ear freely communicates with that in the pharynx, thus
permitting equal pressures on the tympanic membrane. It con-
sists of about one-third bone and two-thirds fibro-cartilage and
fibrous tissue ; their point of junction is the narrowest part of
the tube, the isthmus tiibae.

The osseous 2^0 ft ion is one-half inch long, commencing at the
lower part of the anterior tympanic wall, gradually narrowing
to terminate at the angle of junction of the petrous and
squamous portions of the temporal bone.

The cartilaginous portion is about one inch long, formed by
a triangular plate of elastic fibro-cartilage curved upon itself
into a partial tube ; but inferiorly the margins are not in con-
tact, the defect being filled by fibrous and muscular tissue.

The mucous membrane is continuous with that of the phar-
ynx, and is covered with ciliated epithelium, thick below and
thin above.

Where is the pharyngeal orifice situated?

At the upper lateral portion of the pharynx behind the in-
ferior turbinated bone, above the level of the nasal floor.

Has this tube any special muscles?

Spheno-staphylinus : origin, spine of the sphenoid and the car-
tilaginous tube ; insrrfion, pharyngeal aponeurosis, or soft palate,
palate bone near the posterior nasal spine, or hamular process;
nerve, probably the pharyngeal plexus through the spinal ac-
cessory ; acfioii, lifts the palate or dilates the tube.

Salpingo-pharyngeus : a thin layer bcnieath the mucous mem-
brane, rising from the cartilage of the tube, passing to the
palato-pharyngcus muscle ; nerrc. and action as given above.

Jiare niusc/rs : pterygo-salpingoideus, petro-stujdiylinus, pal-
ato-staphylinus, glosso-staphylinus. The levator and tensor
palati muscles dilate the tube.

372 ESSENTIALS OF HUMAN ANATOMY.

Give the arterial and nerve-supply of the Eustachian tube.

Tlie <(scciuh'u(/ pluLi\ijn<j<'al^ iVoiu the external carotid.

Branches of the middle ineiiiiujeal^ from the internal maxil-
lary.

Branch from the sf^lo-rn/istoid artery.

The nerves are, in addition to those supplying the muscles
of the tube (supra), from the Ji/th and seventh pairs and the
spinal accessory.

The Internal Ear, or Labyrinth.

Name its divisions.

m 1 1 • ,1 • . C Vestibule^ (Ficr. 143),

ihe osseous laounnth, consist- \ ci • • ? i ((i^

(} X ^semicircular canals ,'

ing of

(^ Cochlea*

^ Utricle,

rr,, , 7 7 • ,7 31embranous semicircular

Iha membranous labyrinth, con- ,

• ^- n ^ canals.

sisting of

^Saccule,
Membranous cochlea.

The internal auditory canal, at the bottom of which is the
lamina cribrosa, for the passage of the auditory nerve and ves-
sels and the facial nerve.

The auditory nerve., eighth cranial ( portio mollis), is the spe-
cial nerve of hearing, distributed only to the internal ear.

The organ of Corti is what the retina is to the eye, viz. the
terminal and receptive apparatus.

Describe the internal ear.

It is formed by a series of cavities excavated in the petrous
bone, communicating externally with the middle ear by the
round and oval windows, internally, with the internal auditory
canal ; within the osseous labyrinth, surrounded by the peri-
lymph, is the

Membranous labyrinth — filled with endolymph — upon which
the auditory nerve-filaments are distributed.

Describe the various subdivisions of the osseous labyrinth.

The vestibule is the common central cavity with which all
parts of the internal ear communicate, placed behind the coch-

THE INTERNAL EAR, OR LABYRINTH.

373

lea, in front of the semicircular canals, at the inner side of the
tympanum ; it is ovoid, measuring about one-fifth of an inch
(5 mm.) from before backward, as well as from above down-
ward, less from without inward, and presents

The fenestra ovah's, on its outer wall, closed in the fresh
state by the base of the stapes and its ligament.

The fovea heinisjiherica'^, a small circular depression on its
inner wall, perforated antero-inferiorly by several minute
foramina for the auditory nerves to
the saccule ; the perforated plate is
called the macula cribrosa.

The crista vestibuli is a vertical
ridge behind the macula cribrosa ; its
anterior part is the pyramidal emi-
nence; below, the crista divides and
encloses the fossa cocldearis pierced
by nerve-fibers.

The aqvseductas vestihnli, at the
back part of the inner wall, trans-
mitting a small vein, and the ductus
endolymphaticus. a tubular prolonga-
tion of the lining membrane of the vestibule, ending in a
pouch in the cranial cavity between layers of the dura mater.

The fovea hemielliptica^, a transversely-oval depression on
the roof, separated by the crista vestibuli from the fovea hemi-
sph erica.

The orifices of the semicircular canals^, five in number, open
behind.

The apertura scalse vestihidi cocldese is situated anteriorly.

Fig. 143.— The left osseous
labyrinth laid open ; exter-
nal" view (enlarged) (Leidy).

Describe the semicircular canals S''',^

They are three curved bony tubes, each describing the greater
part of a circle or ellip.sc, of unequal lengths, of a diameter of
-^^ inch (1.5 mm.), each lying at a right angle to the other two
and presenting at one end a dilatation, or ampulla, nearly
double the diameter of the tube (2.5 mm.) ; the

Superior semieircuhir c<tnal^ is vertical, describes about two-
thirds of a circle, passes nt right angles to the posterior surface
of the petrous bone, and forms a projection upon its anterior
surface; it is 20 mm. long; its outer end is its ampulla., open-

374

esse:ntials of human anatomy.

ing separately into the vestibule ; its inner undilated extremity
joins with that of the

Pitsferior aemicircnlar caiuiP^ opening by a common orifice
at the back of the vestibule ; this canal is also vertical, is nearly
parallel to the posterior surface of the petrous bone, and is the
longest (22 mm.), the dilated extremity opening at the lower
back part of the vestibule ; the

External^ or horizoufal semicircular canal\ is the shortest
(15 mm.), and is directed outw^ard and backward ; its ampullated
end opens into the vestibule just above the oval window, its
other extremity by a separate orifice at the upper back part of
the vestibule.

Describe the cochlea.

The cochlea^ (Fig. 144) is conical, somewhat resembles a snail-
shell, and forms the anterior part of the labyrinth ; it is placed

almost horizontally in front of the
vestibule, its apex directed out-
ward, forward, and downward, its
base corresponding to the internal
auditory meatus ; its length is 5
mm., and breadth at base 9 mm.
A^iewed from its base, the right
cochlea is coiled clockwise ; it
presents the

Modiolus^ a central conical
axis, perforated by numerous
canals for filaments of the coch-
lear branch of the auditory nerve,
its apex terminating in a delicate
expanded lamella, like a funnel divided longitudinally, called
the in/undihidiim ; extending from base to apex is a canal, the
canaJis ccnfralis modioli, for a small nerve and artery. Making
two and one-half (two and three-fourths, Quain) spiral turns
around the modiolus is the

iSpiral canal^, about one-twelfth of an inch (2 mm.) in diam-
eter, and one and one-third inches (33 mm.) long, narrowing
from base to apex, there forming the cupola, where the scala
tympani and scala vestibuli, formed by the lamina spiralis,
communicate by the helicotrema.

Fig. 144.— The left cochlea laid
open (enlarged) (Leidy).

THE INTERNAL EAR, OR LABYRINTH. 375

The coclilea presents three openings : the fenestra rotunda,
connecting the scala tympani with the middle ear, an oval
opening from the scala vestibuli into the vestibule, and that
of theaqucneductiis cochleae ^ for an emissary vein; projecting
from the modiolus is the

Lamina spiralis" (Fig. 144), a process formed of two bony
lamella?, between which are numerous canals for nerve-fibers,
defective in the last half turn of the cochlea, leaving an aperture,
the helicotrema, and terminating by the hook-like hamiilar
2)rocess''] winding around the modiolus at the point of attach-
ment of the lamina spiralis is the canalis spiralis modioli, lodg-
ing the enlargement of the cochlear nerve containing ganglion-
cells, called theffanglion spirale, whence come the nerve-branches
to the organ of Corti.

What is the scala vestibuli '" (Fig. 144)?

It is that portion of the canal of the cochlea above the lamina
spiralis and membrane of Reissner, communicating with the
vestibule below and the scala tympani above, by the helico-
trema ; it is filled with perilymph.

Describe the scala tympani «^

It is that portion of the spiral canal below the lamina
spiralis and the membranous cochlea, terminating below
at the round window— which is closed by a membrane, the
memhrana tympani secundaria — and communicating above
with the scala vestibuli at the helicotrema ; it is filled with
perilymph.

What is the aquseductus cochleae '^ ?

A small canal transmitting a vein from the cochlea to the in-
ferior petrosal sinus, commencing at the lower wall of the scala
tympani, and ending to the inner side of the carotid canal on
the inferior surface of the petrous bone.

Describe and name the subdivisions of the membranous
labyrinth (Fig. 145).
It consists of a series of closed membranous sacs containing

eiidolympli ; its various parts are called

_-,' „ , , . r. ,1 ( Utricle, ] two membra-

The vestihnle, consisting of the | ^v,v,^.^.„^,^ | ^^^^ .^es,

with the former of which communicate the three

376 ESSENTIALS OF HUMAN ANATOMY.

Memhranons semicircular cannh.

The utricle and saccule are separate, but are indirectly con-
nected by a minute canal passing from the saccule to a similar
one from the utricle, forming the endolymphatic duct which
passes along the aquaeductus vestibuli to end by a blind pouch
on the posterior surface of the petrous bone ; the saccule com-
municates with the scala media by the caiiah's reimiens. The
endolymph in all parts thus communicates freely.

Describe the utricle.

It is an oblong, laterally compressed sac, filled with endo-
lymph, placed in the upper back part of the vestibule in the fovea
hemielliptica, communicating behind w^ith the membranous semi-
circular canals by five openings, and has distributed, chiefly at
one part of its walls, numerous branches of the auditory nerve,
at which point is a round mass of minute crystals of calcium
carbonate, bound together by delicate fibrous tissue forming
the otolithic, otoconia^ or ear-stohes ; the thickening of the wall
both of the utricle and saccule, where the nerves penetrate,
is called the mucvla acustica.

.^

Ductus
£fido-iynij>AatieaS

C^

Fig. 145.— The right membranous labyrinth ; external view (enlarged) (Gray).

What are the membranous semicircular canals ?

They are three canals of the same shape, but one-fifth to one-
third the diameter of the containing osseous canals, to which
they are fastened by numerous fibrous bands ; their five ori-
fices open into the utricle. Each has three coats, Jihrons^ tunica
propria, and an epithelial lining.

THE INTERNAL EAR, OR LABYRINTH.

^77

Describe the saccule.

It is a globular sac, smaller
than the utricle, to which it
is attached at one point, and
lies in the fovea hemispherica;
it is surrounded with peri-
lymph, and indirectly com-
municates by a short canal
with the utricle and with the
membranous cochlea or scala
media by the caualis reiiniens
of Hensen, a funnel-shaped
duct, 1 mm. long, and 0.5 mm.
wide. The saccule is 3 mm.
d 2 mm. broad ; it

Fig. 146.— Section of the first turn of
the cochlea, showing the three scalse
(enlarged;. (Leidy;

an

contains a small bundle of otoliths ; numerous nerves open on
its floor upon a macula.

What is the membranous canal of the cochlea" (Fig. 146)?

More usually called the scala iiiedia^ caualis coclilese^ or the
ductus cochlearis^ it begins by a blind extremity at the lower
anterior portion of the vestibule, enters the cochlea, where it
forms in cross-section a triangular canal, its base being the
outer wall of the cochlea, its lower wall the memhrana hasil-
ori'.s'', its upper the membrane of Reissner'^ \ it is filled with
endolymph and contains the organ of On-ti"", covered by the
delicate memhrana. tectorial parallel with the basilar membrane**.
The periosteum on the upper surface of the osseous spiral
lamina forms an elevation, the

Limhus lamina, spiralis "% which presents an upper and a lower
margin called respectively the lahiam vestihnlare and lahium
tijmpanicum, the groove formed between these being termed
the sulcus spiralis^, shaped like the letter C.

What is the membrane of Reissner '' ?

A delicate membrane stretched between the outer wall of
the cochlea and the periosteum of the vestibular surface of the
osseous spiral lamina near the commencement of the Umbus
lamin;« spiralis"', forming the upper wall of the scala media.

378 ESSENTIALS OF HUMAN ANATOMY.

What is the membrana basilaris '' ?

A thin membrane passing from the labium tympanicum to
the wall of the cochlea, where it expands into the triangular
llgamoitum sptrult^"^. It forms a part of the floor of the scala
media, supporting on its upper surface the organ of Corti ''".

Describe the membrana tectoria or membrane of Corti '.

A delicate membrane rising from the upper surface of the
limbus near the attachment of the membrane of Ileissner "",
passes over the superior labium, and dips down into the spiral
groove like a pad ; it runs nearly parallel with the basilar mem-
brane**, rests upon the organ of Corti'"", and ends in the outer
hair-cell region.

Describe the organ of Corti'' (Fig. 147).

It consists of a complex body formed by a series of some
three thousand arches roofing over a space called the zona
arcuata. formed of rods and epithelial hair-cells, lying upon
the membrana basilaris*" and covered by the membrana tectoria' ;
the

Rods of Corti are disposed in two rows, the inner ^^ and
outer ^^ ?-ofZ.s, each rod with its swollen base resting upon the
basilar membrane'', and its expanded upper end inclined toward
and in contact with the opposite one, forming an arched canal ;
the upper end of the inner rod resembles the upper end of the
human ulna ; the same end of the outer rod resembles a swan's
head ; there are about 5600 inner rods, 4000 outer rods ;
hasilar celh occupy the angle between the base of each rod
and the basilar membrane.

Fig. 147.— a pair of rods of Corti, from the rabbit (highly magnified) (Leidy).

Hdir-cens"^ (Fig. 148) are epithelial cells with stiff hair-like
cilia /5 ; outer hair-cells, external to the outer rods"', present four
rows, numbering about 12,000 ; inner hair-cells present a single

THE I^TER^:AL EAR, OR LABYRINTH.

379

row internal to the inner rods*"^, numbering about P>500. Each
hair-cell, outer or inner, has about 20 hairlets. Beneath and
between the hair-cells are the cells of Dieters^ each expanding
into 2l phalangeal process ; the

Lamiaa reticularis is formed of several rows of small
fiddle-shaped cuticular structures called phalanges^ con-
nected together and to the heads of the
outer rods, forming rings °'°'', through
which project the hairs of the outer hair-
cells.

Describe the auditory nerve.

Its snperjjcial origin is by two roots,
wcs/«/, from the groove between the olivary
and restiform bodies at the lower border
of the pons (page 246) ; the other, lateral,
winds around the restiform body appar-
ently connected with the auditory stri^.
It enters the internal auditory canal with
the facial nerve, and at its end divides
into an upper vestihular portion which
comes from the mesial root only, and a
loirer portion which belongs wholly to
the lateral root and passes through the
foramina below the crista falciform is ; it
gives off a posterior brancli and the coch-
lear nerve.

It is here necessary to mention some of
the bony parts involved. The end of the internal auditory
canal is the lamina cribrosa, transmitting the nerves as seen'
in the diagram (Fig. 149).
Crista falcifonnis runs across
the l((min(f, separating a small
superior fossa from a large in-
ferior one. The upper fossa is
the frrea crihrosa superior ; ante-
rior to it is the orifice of the
aquoL'ductus Fallopii for the en-
trance of the facial nerve. The inferior fossa shows posteriorly
(1) area crihrosa media, (2) foramen singnlare, anteriorly (X»)

Fig. 148.— View of a
small partofthelnnnan
organ of (orti, from
above (highlj* magni-
fied).

CristaFcdcif -
/br.Cent.CocA

SpirHr

Jr.CriUufe.

■Jr.CrikMecL
for.Sinq.

Fro. 149.— Fnndu.s of the riglit in-
ternal anditory meatus ((iuain).

380 ESSENTIALS OF HUMAN ANATOMY.

tractus spiraJii^ foramiituleufus, ending in the foramen centrale
cocldesfL for the cochlear nerve.

The vestibular division of the auditory nerve splits into fila-
ments which pass through the area cribrosa superior^ and enter
the vestibule through the macula cribrosa, to be distributed to
the utricle and the ampullae of the external and superior semi-
circular canals.

The inferior division by its posterior branch sends twigs
through the area cribrosa media and the openings of the
fovea hemispherica to supply the saccule ; it sends another
branch through the foramen singidare to the ampulla of the
posterior semicircular canal ; the

Cochlear nerve divides into numerous filaments at the base
of the modiolus which enter its canals, pass between the two
plates forming the lamina spiralis, forming a plexus which con-
tains ganglion-cells, and sends branches to supply the inner and
outer hair-cells ; the

Intumescentia ganglioformis Scarpse is on the vestibular
branch in the internal auditory canal ; the two ganglia of
Corti are on the nerve to the posterior ampulla.

The ganglion sjyirale is on the cochlear nerve in the canalis
sjiira/is modioli.

The branches of the auditory nerve and the apertures by
which they leave the meatus are shown in the following table :

o . J. . . TTo utricle ") . .,

feuperior division or i rp • n f Area cribrosa

^^•11 ^ Lo superior ampulla y

vestibular nerve . j m i i n I superior.

(^ io external ampulla J ^

Inferior
division

r rr 1 f Area cribrosa

. T^ ^ . io saccule < -,•

J Posterior J ( media.

1 branch ] m , • n f Foramen sin-

'^ io posterior ampulla < ,

^ ( gulare.

n ■l^ ( Tractus spiralis foraminu-
Cochlear i i , i x»

■s lentus and toramen cen-
nerve j . ^ ^ ^

(^ trale cochlea.

Give the arterial supply of the labyrinth.

The internal auditory, a transverse branch of the basilar,
enters with the nerve the internal auditory canal, there to di-
vide into a vestibuhr and a cochlear branch ; the sti/Io-mastoid,
from the posterior auricular ; occasionally branches from the
occipital.

THE ANATOMY OF INGUINAL HERNIA. 381

THE ANATOMY OF INGUINAL HERNIA.

What is the inguinal canal?

The canal passing downward and inward fur one and one-half
inches (3.5 cm.), which lodges the spermatic cord in the male,
the round ligament in the female, pursuing a course nearly
parallel to Poupart's ligament through or between the abdom-
inal muscles, commencing at the internal abdominal ring and
terminating at the external abdominal ring*^ (I'ig- 150).

Describe the internal abdominal ring.

It is an ovoidal opening in the transversalis fascia ^^ midway
between the anterior superior iliac spine and the symphysis

■'" iiKi'i'jfcv \\\\«ii«i>; W/u','"^'!AJ '/'/'■

Fig. 150.— The anatomy of inguinal and femoral hernia (Leidy).

pubis, about half an inch above Poupart's ligament*^. It is
bounded above and externally by arched fibers of the trans-
versalis muscle"*, below and internally by the epigastric ves-
sels''*; from its circumference passes the iii/nndibuUf arm fascia
on to the spermatic cord or round ligament.

What is the external abdominal ring"?

An obli((uely triangular ojxining in the aponeurosis'^ of the
external oblifjue muscle', just above the crest and to tlie inner
side of the spine of the piibes; from base to apex it averages one
inch, by half an inch transversely. It is bounded below by the

382 ESSENTIALS OF HUMAN ANATOMY.

crest of the pubes, above and in front by the curved interco-
lumiuir jihcrs'' and on each side by the free borders of the apo-
neurosis called the internar" and external columns^ or pillars of
the ring ; from the margins of the ring passes on to the cord
or round ligament, the inf ercol inu nar fascia .

Give the boundaries of the inguinal canal.

Anteriorly, the skin, superticial fascia, the aponeurosis of the
external oblique throughout, and the outer third of the internal
oblique muscles.

Posteriorly, the triangular fascia of the abdomen, conjoined
tendon ^^ of the internal oblique and transversalis muscles,
transversalis fascia ^^, subperitoneal tissue, and peritoneum.

Superiorly, the arched fibers of the internal oblique^" and
transversalis muscles.

Inferiorly. the union of the transversalis fascia ^^ with Pou-
part's and Gimbernat's ligament*'.

What is Poupart's ligament^?

The infolded, thickened margin of the aponeurosis of the ex-
ternal oblique, extending from the anterior superior iliac spine ^
to the spine of the pubes, from which it is reflected a short
distance along the pectineal line, forming Gimhernat' s ligament ;
an oblique band of fascia or tendinous fibers arises from the
external oblique aponeurosis of one side to be inserted into the
pubic crest and the pectineal line of the opposite side, passing
inward beneath the spermatic cord behind the inner pillar, in
front of the conjoined tendon ; it is called the triangular fascia
of the abdomen ; the lower part of Poupart's ligament forms
the external pillar of the external abdominal ring*.

Describe the relations of the epigastric artery and the inter-
nal abdominal ring.
It passes between the transversalis fascia and the peritoneum
along the lower inner margin of the internal ring beneath the
spermatic cord.

What is the cremasteric fascia?

A series of muscular loops connected by areolar tissue in-
vesting the spermatic cord, supposed to have been derived from
the internal oblique muscle during the descent of the testicle,
and, of course, absent in the female.

FEMORAL HERNIA. 383

What is Hesselbach's triangle ?

A triangular space at the lower part of tlie inner surface of
the abdominal wall, bounded externally by the epigastric artery,
and a fold of the peritoneum covering it, the j}/ica epigastricd;
internally by the margin of the rectus muscle, and below by
Poupart's ligament ; the conjoined tendon stretches across the
inner two-thirds of this space.

What is an external or oblique inguinal hernia?

A protrusion of an abdominal viscus, usually of the bowel,
omentum, or both, following the course of the spermatic cord
in the inguinal canal through both the internal and external
rings (icheii complete), the neck of the sac being to the outer
side of the epigastric artery.

What are the coverings of an oblique inguinal hernia?

Skin; superjickd fascia ; intercolainnar fascia; cremasteric
fascia ; infundihuliform fascia^ modified transversalis fascia ;
subserous cellular tissue; and peritoneum forming the sac.

Where is the seat of stricture most apt to be?

(1) At the internal ring, (2) the inguinal canal by fibers of
the internal oblique or transversalis muscles, (3) at the exter-
nal ring, provided it is not at the thickened neck of the sac,
the most usual site in old hernise.

What is an internal or direct inguinal hernia?

One wliere the protrusion passes through some part of Hes-
selbach's triangle, passing directly through the external ab-
dominal ring, the neck of the sac being internal to the epi-
gastric vessels.

What coverings has a direct hernia?

The same as an oblique, except that the transversalis fascia
takes the place of the iufandihuliform fascin , and the con joined
tendon is substituted for the cremasteric fascia ; the fibers of
the tendon may be forced apart or distended as an investment.

FEMORAL HERNIA.

Describe the femoral or crural canal (Fig. 150).

ft lies beneath Foupart's ligament", to the inner side of the
femoral vein'^, extending from the femoral ring above to the

384 ESSENTIALS OF HUMAN ANATOMY.

S((j}Jt('itoi(s opcniuy^' below ; it is about half an inch long, closed
above by the sej)tnm cj-ura/c, formed of* condensed areolar tissue,
and below by the ci'tbri/orm fascia, derived from the deep layer
of the superficial fascia, or from the fascia lata, covering the
saphenous opening.

The femoral or crural ring is an oval space between the
femoral vein and (rim])eriiat's ligament, three-fifths to one inch
in diameter, larger in the female than in the male, situated be-
low and internal to the internal abdominal ring ; it is closed
by the septum crurale and a lymphatic gland ; the

Saplicnous opciiing^\ fossa ovalis, is an ovoidal opening one
and a half inches long by half an inch wide, below the inner
portion of Poupart's ligament'^, formed by the pubic portion ^^
of the fascia lata passing behind the femoral vessels, while contin-
uous with it by the inferior cornn is a stroug falciform process of
Barns ^^, the iliac portion of the fascia lata, ])assing in front of the
vessels, its narrow pubic portion blending with the attachment
of Poupart's and Gimbernat's ligaments ; this is called Ileifs
ligament^^ or the superior cornu ; the opening is covered in by
the cribriform fascia.

Bound the crural canal.

Anteriorh/ lie the transversalis fascia^\ Poupart's ligament^,
and the falciform process of the fascia lata^'' ;

Posteriori}/^ iliac fascia, covering the pubic portion of the
fascia lata ;

External It/, the fibrous septum separating it from the femoral
vein ;

Internall//, the junction of the processes of the transversalis
and iliac fasciae fonning the femoral sheath lying against the
outer concave edge of Gimbernat's ligament.

Describe the position of parts around the ring.

The spermatic cord in the male, the round ligament in the
female, lie just above the anterior margin ; the

Femond vein^^ lies upon its outer side ; the

Epigastric artery crosses the upper outer angle of the ring;
the

Obturator artery once in three and a half cases arises in
common with the epigastric, when it may closely skirt around
the upper and inner margins of the ring.

THE PERINEUM AND ISCHIO-RECTAL REGIONS. 385

Describe the septum crurale.

It is a layer of condensed cellular tissue upon which lies a
small lymphatic gland, closing the femoral ring.

What is the crural sheath ?

It is a continuation downward of the fascia transversalis in
front, and of the iliac fascia behind the femoral vessels forming
their sheath, divided by two septa into three compartments for
the femoral artery externally, the femoral vein next, and leav-
ing a third internally, the femoral oanal, or opportunity for ic.

Describe the deep crural arch.

When present it is a band of fibers derived from the trans-
versalis fascia, crossing the front of and adherent to the crural
sheath, passing from the center of Poupart's ligament, the
superficial crural arch, to the pectineal line behind the con-
joined tendon.

Where is the seat of stricture most apt to be ?

At (1) the junction of Hey's and Gimbernat's ligaments,
(2) the margin of the saphenous opening, (3) the neck of the
hernial sac.

What are the coverings of a femoral hernia?

They are skin, siq^er/icial fascia, cribriform fascia, crural
sheath, sejytum crurale, subserous areolar tissue, and peritoneum
forming the sac.

THE PERINEUM AND ISCHIO=RECTAL REGIONS.

Perineum (Fig. 151) includes the outlet of the pelvis from
the apex of the subpubic arch to the tip of the coccyx, between
the ischial tuberosities ; breadth, three and a half inches
(9 cm.) ; length, four inches (10 cm.). A transverse line just
in front of the anus marks an anterior urethral part, true per-
iueum, and a posterior anal jxirt, the ischio-rectal region.

Ischio-rectal fossa^, of a triangular shape, between the end
of the rectum" and the tuberosity of the ischium" on each side;
its base corresponds to the skin, and apex to the point of
division of the obturator fascia and the origin of the anal
fascia ; its base is about one inch broad, its depth two inches,
being deepest behind, and is bounded internally, by the

25

386 ESSENTIALS OF HUMAN ANATOMY.

sphincter ani^. levator ani^, and coccygeus® muscles ; externally^
by the tuberosity of the ischium" and obturator fascia ; in
froiit^ by the line of junction of the superficial and deep
perineal fasciae; and hr/u'nd, by the margin of the gluteus
maximus muscle'^ and the great sacro-sciatic ligament.

Internal pudic ve.ssrh and nerve run about one and a half
inches above the margin of the ischiatic tuberosity, in Alcock's
canal.

Inferior hemorrhoichd vessels, occasionally large enough to
give trouble after lithotomy, traverse the center of each fossa.

What is the perineum ?

It is the anterior portion of the pelvic outlet, in front of the
ischio-rectal region ; it is of a triangular form, bounded, deeply,
by the rami of the pubes and ischia, forming, superiorly, the
pubic arch, and behind, by a line drawn between the ischiatic
tuberosities ; lateral boundaries measure three to three and a
half inches. The central point of the perineum is one inch,
membranous urethra one and a half inches, in front of the
anus.

Describe the muscles of the perineum.

External sphincter ani "^ : origin^ the tip of the coccyx'' by a
tendinous band and superficial fascia ; insertion, the tendinous
center of the perineum'^; action, closes the anus ; nerve, the fourth
sacral and the inferior hemorrhoidal of the pudic.

Internal sphincter ani : consists of an aggregation of the
involuntary circular fibers of the intestine, forming a muscular
ring around the anal canal two lines thick and one inch broad.

Sphincter tertius (p. 276) : a transver.se fold extending into
the rectum on the right .side three inches above the anus.

Accelerator urinse^ bulho-cavernosus : it has symmetrical halves
with a median raphe ; origin, central tendon of the perineum'-^ and
the median raphe in front ; insertion, fibers spread over the
front of the triangular ligament, encircle the bulb and corpus
spongiosum, spread over the sides of the corpora cavernosa, to
which they are partly attached and partly terminate in a tend-
inous expansion covering the dorsal vessels of the penis ; action,
empties the urethra after the bladder ceases to contract, per-
haps aids in the erection of the penis ; nerve, perineal branch
of the pudic,

THE PERINEUM AND ISCHIO-RECTAL REGIONS. 387

Erector penis'*, ischio-cavernosus : origin^ inner surface of the
tuberosity of the ischium, and the adjacent portion of its
ramus {erector ditoridis in the female arises from the ischial
tuberosity ; utserted on the side of the crus clitoridis) ; inser-
tion^ by an aponeurosis covering the crus penis into the outer

Fig. 151.— The muscles of the perineum (Leidy).

side and the under surface of that body ; action^ maintains
erection ; nerve, perineal of the pudic.

Transversus perinei^ : origin, inner front side of the tuberosity
of the ischium ; insertion, tendinous center of the perineum
meeting its fellow, external sphincter, and accelerator urinae ;
action, steadies the perineal center ; nerve, perineal of the pudic.

Levator anr : origin, posterior surface of the body of the
OS pubis, spine of the ischium, from the " white line," which
is the angle of division between the obturator and recto-
vesical layers of the pelvic fascia; insertion, sides of the apex
of the coccyx**, opposite muscle by a median fibrous raphe,
extending from the coccyx to the anal margin, the side of
the rectum (or vagina) blending with the s])hinctcr muscles,
and the side of the prostate gland, uniting beneath it with the
opposite muscle mingling with the external sphincter and trans-

388 ESSENTIALS OF HUMAN ANATOMY.

versus perinei muscles at the perineal center ; action, supports
tlie rectum, vagina, and pelvic viscera, and with its fellow helps
to form the floor of the pelvis, a muscle of forced expiration ;
nerves, perineal of the ])udic and the fourth sacral.

Compressor or constrictor uretlirse : oriyln. aponeurotic, from
the ischio-pubic rami on each side, from layers of the triangu-
lar ligament; insertion, each muscle divides, surrounding the
urethra from the prostate gland to the bulb of the urethra,
uniting with the opposite muscle above and below this tube
by a tendinous raphe: action, shut-off muscle; nerves, dorsal
nerves of the penis from the pudic.

Coccygeus^ : origin, from the spine of the ischium, lesser sacro-
sciatic ligament, or obturator fascia ; insertion, into the margin
of the coccj'x and the side of the lowest segment of the sac-
rum ; action, raises the coccyx; completes the pelvic floor;
iierif. anterior branch of the fourth and fifth sacral.

Sphincter vaginae surrounds the vaginal orifice, and is homolo-
gous with the accelerator urinaB in the male ; origin, central ten-
don of the perineum ; insertion, corpora cavernosa of the clitoris.

Erector clitoridis : it replaces the erector penis muscle.

Describe the perineal fasciae.

The siijx rjiciaJ layer ejf the superficial fascia is thick, loose,
loaded with fat. and continuous with the fasciae of the ischio-
rectal and crural regions ; it has no bony attachments ; the

Deep layer of the superficial fascia, sup>erficial perineal fascia,
Colles fascia, are three names for an aponeurotic layer, con-
tinuous in front with the dartos of the scrotum, is firmly at-
tached to the margins of the ischio-pubic rami, external to the
crura of the penis as far back as the ischial tuberosities, and
passes behind the transversus perinei muscles to become the
anterior layer of the deep perineal fascia.

The anterior layer of the deep perineal fascia is attached
above and laterally to the pubic arch, subpubic ligament and
rami of the ischium and pubes beneath the crura of the penis,
forming a dense membranous lamina, extending and attached
to the tendinous perineal center becoming continuous with the
deep layer of the superficial fascia behind the transverse peri-
neal muscles ; it embraces the anterior extremity of the mem-
branous urethra, which passes through it one inch below the
symphysis pubis, and is continued forward upon it.

THE PERINEUM AND ISCHIO-RECTAL REGIONS. 389

The posterior layer of the deep perineal fascia is attached like
the preceding, but more posteriorly, embraces the back of the
membranous urethra, and is continued backward over the outer
surface of the prostate gland, the two layers forming the tri-
angular ligament ; the portion of the urethra embraced between
these layers is the membranous urethra.

The p>^^vic fascia shows a white line passing from the lower
part of the symphysis pubis to the spine of the ischium ; this
marks the line of division into two layers, obturator and recto-
vesical fasciie. The former covers the lower part of the obtu-
rator internus, gives off anal fascia to the under surface of the
levator ani ; passing across the subpubic arch it forms the pos-
terior layer of the triangular ligament.

The recto-vesical fascia, or visceral layer of the pelric fascia.,
descends into the pelvis upon the upper surface of the levator
ani muscle, investing the prostate, bladder, and rectum.

Describe Buck's or Colics' fascia.

It is a moderately dense fascia investing the penis as far as
the glans, being a prolongation downward of the deep layer of
the superficial abdominal fascia, forming the dartos of the
scrotum ; it directs the urine forward into the scrotum, penis,
and upon the abdomen in rupture of the urethra.

What layers of fascia form the triangular ligament ?

The superficial and deep layers of the (hep perineal fascia^
or the anterior and posterior layers of the triangular ligament
(body horizontal), or the inferior and superior frianguhir liga-
ments (body erect) ; there are three names for each layer.

What structures lie between the layers?

Memhranons urethra, Cowpers glands and ducts,

Compressor vrethrse. muscle, Internal pud ic vessels,
Subpubic ligament, Pudic nerves,

Dorsid vessels of the penis. Arteries and nerves of bulb,
Dorsal nerves of the jyejiis, Venous plexus.

What structures are exposed by the removal of the deep
layer of the superficial fascia?
The erector penis muscles covering the crura of the j)enis.
The accelerator urinae muscle covering the corpus sjiongiosiim

and bulb,

390 ESSENTIALS OF HUMAN ANATOMY.

Transversns pcrlnci mitscles,
Transverse perineal arteries^
Superficial perineal vessels.

What parts are divided in lateral lithotomy ?
Skin,

Superficial and Colics'' fascia,
Inferior hemorrhoidal vessels and nerves,
Posterior fibers of the accelerator urinse muscle,
Transversus perinei muscle and vessels,
Stiperficud perineal vessels and nerves.
Triangular ligament, two layers.
Anterior filters of the levator ani.
Part of the compressor urethrse.
Membranous and prostatic portions of the urethra,
Lateral lobe of the prostate gland.

What structures must be avoided in this operation?

In front, the bulb and its artery.

Externally, the internal pudic vessels and nerve.

Toiuard the median line and posteriorly, the rectum or neck
of the bladder, the entire division of the lateral lobe of the
prostate, venous plexus, or pelvic fascia.

Briefly describe the special points of interest connected with
the female perineum.

The perineal body is the point of junction of all the muscu-
lar and aponeurotic structures of the perineum, forming a
pyramidal mass of tissue extending for some distance up be-
tween the rectum and vagina, upon the integrity of which de-
pends the proper support aiforded to the pelvic viscera by the
fioor of the pelvis.

The length of the female perineum is only about one inch,
extending from the posterior commissure to the verge of the
anus; the accelerator urinpe muscle is replaced by the sphincter
vaginse encircling the vaginal outlet ; the triangular ligament,
formed essentially as in the male, and perforated by the ure-
thra and vagina, is much smaller and weaker.

INDEX.

Abdomen, 289

muscles of, 156

openings in, 289

regions of, 290
Abdominal aorta, 201

surgical anatomy, 212

regions, 290

ring, external, 381
internal, 381

viscera, 289
Abflucens nerve, 246
Abductor hallucis, 179

minimi digiti, 169, 180

pollicis, 168
Accelerator urinse, 386
Acetabulum, 83

Aci-omio-clavicular articulation, 126
Acromion process, 92
Acromio-thoracic artery, 197
Adductor brevis, 172

longus, 172

magnus, 172

obliquus hallucis, 180
pollicis, 168

transversus liallucis, 181
pollicis, 168

tubercle of femur, 109
Agminated glands, 274
Alar thoracic artery, 198
Alim(!ntarj' canal, subdivisions of,

260
Alveolar artery, 344

process, 46
Alv(!oli of lungs, 307
Ainpulla of labyrinth, 373
Ampullsr' of maiinna, 339
Amygdala of ccrchcllum, 237
Anal canal, 276
Anastomotica magna, 198, 208
Anatomical neck of humerus, 95

Anatomy, definition of, 17

descriptive, 17

regional, 17

surgical, 17
Anconeus, 166
Angle of jaw, 56

subscapular, 91
Angular gyrus, 227

processes of frontal bone, 23
Anlile-joint, 137
Annular ligament, anterior, 167
of foot, 178
posterior, 167
of stapes, 369
of wrist, 130
Annulus ovalis, 183
Anterior fossa of skull, 58
j Antihelix, 363
j Antitragicus, 364
j Antitragus, 363
Antrum of Highmore, 46
Anus, 276
Anvil, 368
Aorta, 188

abdominal, 201

relations of, in thdrax, 189

thoracic, 200
Aortic plexus, 259

valve, 182
Apex of lung, 303
Ai)oneuroses, 141
Apoi>hysis, 21
Api)endages of eye, 359
Appendices ejiiploicee, 276
Appendix aiiricula', 183

vermiformis, 275
Aqujeductus cochleip. 38, 375

vestihuli, 38, 60, 373
Aqueous cliamhers, 354

humor, 354

392

INDEX.

Aiacbnoifl, 223, 240
Arbor vitte uterina, 335
Arch, supra-orbital, 23
Area cribrosa, 379
Areola of nii)i)le, 339
Arm, bones of, 95

nuiscles of, IGl
Arnold's ganglion, 244
Arrectores pi lorn ni, 342
Arteria centralis retinse, 357
Arteriae proprijc renales, 315

receptaculi, 194

rectse, 315
Arteries, 186

of ankle-joint, 137

of auricle, 364

of bladder, 321

cerebral, 194

of choroid, 349

coronary, 189

of elbow-joint, 129

of esophagus, 270

of Eustachian tube, 372

of eyeball, 357

of eyelids, 360

helicine, 326

of hip-joint, 133

interlobular, 315

of iris, 351

of kidney, 315

of knee-joint, 136

of labyrinth. 380

of larynx, 300

of liver, 282

of lungs, 307

of mammfe, 340

of ruembrana tvmpaui, 366

of nose, 343, 344

of ovaries, 339

of pancreas. 284

of penis, .326

of pharynx, 269

of retina, 3.52

of sclerotic, .347

of shoulder-joint, 128

of stomach, 272

structure of, 187

surgical anatomv of, 211

of testicle, 329

of trachea, .303

of tympanum, .369

of uterus, .3.36

of wrist-joint, 130
Artery, acromio-thoracic, 197

Artery, alar thoracic, 198
alveolar, 344
auricular, posterior, 192
ax i liar V, 197
basilar,' 196
brachial, 198
bronchial, 200
carotid, common, 190

internal, 193
celiac axis, 201
ciliary, .357

circumflex, posterior, 198
coronary, of stomach, 201
cremasteric. 3.30
dorsalis pedis, 210
epigastric, deep, 205

circumflex, 206

superficial, 208

superior, 196
esophageal, 200
facial, 192
femoral, 206
gastric, 201
gluteal, 205
hepatic, 202, 281
hypogastric, 204
iliac, 204

common, 203

external, 205

internal, 203

superficial circumflex, 208
ilio-lumbar, 205
infraorbital, .3.57
innominate, 189
intercostal, 201

superior, 196
lacrimal, 357
lingual, 191
lumbar, 203

mammary, internal, 196
maxillary, internal, 192
medullary, 19, 198
mesenteric, inferior, 202

superior, 202
metatarsal, 210
musculo-phrenic, 196
obturator. 204
occipital, 192
ophthalmic, 194, 357
ovarian, 203, 336
palpebral, 3.57
pericardial, 200
peroneal, 210
pharyngeal, ascending, 192

INDEX.

393

Artery, phrenic, inferior, 202

plantar, external, 211
internal, 211

popliteal, 208

profunda, inferior, 198
superior, 198

pudic, internal, 204

pulmonary, 187

radial, 199

renal, 202, 315

sacral, lateral, 205
middle, 203

sciatic, 204

spermatic, 203, 329

splenic, 202, 286

subclavian, 195

subcostal, 201

subscapular, 198

supraorbital, 357

suprarenal, inferior, 203
middle, 202

suprascapular. 196

tarsal, 210

temporal, superficial, 192

thoracic, long, 198
superior, 197

thyroid, 196

superior, 191

tibial, anterior, 209
posterior, 210

tympanic, 194, 370

ulnar, 199

uterine, 204, 336

vertebral, 196

vesical, 204
Arthrodia, 118
Articular cavities of bone, 21

nerve of internal po])liteal, 254

processes of vertebra, 71
Articulations, 117

acrornio-clavicular, 126

astragalo-navicular, 138

atlanto-axial, 120

carpal, 130

carpo-metacarpal, 131

chondro-sternal, 123

costo-central, 122

costo-transvcrse, 123

costo- ventral, 122

ijitcrfboridral, 124

int( rplialangcal, 132. 139

of btwcr extremity, 1.32

metacari»o-pbaIan;i('aI, 132

mctatarsd-plialanfrcal, 1.39

Articulations, occipito-atlautal, 119

radio-ulnar, 129

sacro-coccygeal, 125

sacro-iliac, 124

sacro-vertebral, 124

sterno-clavicular, 126

tarsal. 138

tarso-metatarsal, 139

temporo-maxillary, 122

tibio-fibular, 1.36 "

vertebral, 119
Aryteno-epiglottideus inferior, 300

superior, 300
Arytenoid cartilages, 296
Arytenoideus, 300
Ascending colon, 275

frontal convolution, 227

parietal convolution, 227
Astragalus, 113

Atlanto-axial articulation, 120
Atlas. 72

Attolens aurem, 142
Attrahens aurem, 142
Auditory canal, external, 364

nerve, 246, 379
Auricle, 363

arteries of, 364

left, 184

right, 183
Auricular artery, posterior, 192

fissure, 39 "

surface of sacrum, 76
Auriculo-ventricular groove, 182, 183

orifice, 183
Axillary arterj-, 197

surgical anatomy, 212

vein, 215
Axis, 72, 73
Axis cylinder, 222
Azygos uvulae, 148

veins, 217

Back, muscles of, 150
Bartholin, duct of, 264

glands of, 333
Basal ganglia, 229
Ba.silar arterv, 196

cells, 378

groove, 30

process of occipital, 29
Basi-occipitals, 27
Basi-sphenoidal suture, .57
Baubin, valve of, 273
Bic(!ps, 174

394

INDEX.

Biceps, flexor cubiti, 162
Bicipital groove, 95
Bicuspid teeth, 261
Bladder, 318

ligaments of, 319

nerve-supply of, 321

structure of, 320

vessels of, 321
Blind spot, 352
Body, ciliary, 349

perineal, 390

pituitary, 229

restiform, 235

of vertebra, 70

vitreous, 354
Bone, astragalus, 113

atlas, 72

axis, 73

chemical composition of, 17

clavicle, 89

coccyx, 77

cuboid, 114

cuneiform, 103, 114

ethmoid, 40

femur, 106

fibula, 112

frontal, 22

humerus, 95

hyoid, 76

ilium, 85

of the Incas, 27

incus, 368

innominate, 83

ischium, 86

lacrimal, 48

malar, 49

malleus, 368

maxillary, inferior, 54
superior, 43

microscopic structure of, 18

nasal, 43

navicular, 114

occipital, 27

OS calcis. 113

OS maguum, 104

palate, 50

parietal, 25

patella, 109

pelvis, 88

phalanges of foot, 117
of hand, 106

pisiform, 104

pubes, 87

radius, 100

Bone, sacrum, 74

scaphoid, 102

scapula, 91

semilunar, 102

sphenoid. 31

stapes, 368

sternum, 80

temporal, 35

tibia, 110

trapezium, 104

turbinated, 42
inferior, 52

ulna, 97

unciform, 104

vomer, 53
Bones of arm, 95

classification of, 20

of foot, 113

of forearm, 97

of hand, 102

of head, 22

of lower extremity, 106

of trunk, 69

of upper extremity, 89

long, 20

number of, 20

pelvic, 83

sesamoid, 20

Wormian, 20
Bowman's capsule, 313

membrane, 348
Brachial artery, 198

surgical anatomy, 212

plexus, 249
Brachial is anticus. 163
Brachio-radialis, 165
Brain, 224

convolutions of, 226

fissures of, 225

ventricles of, 231

weight of, 224
Brim of pelvis, 88
Broad ligament of liver, 277, 278
pulmonary. 308
of uterus, 335
Bronchi, 302
Bronchial artery, 200
Bronchioles, 307
Bruch, membrane of, 349
Brunner's glands, 274
Buccinator, 144
Buck's fascia, .389
Bulb of corpus callosum, 325

of corpus spongiosum, 325

INDEX.

395

Bulbi vestibuli, 333
Bulbs, olfactory, 232
Burns, falciform process of, 384
Bursa, pharyngeal, 268
subcrural, 134

Calamus scriptorius, 234
Calcarine fissure, 226
Calices of kidney, 313
Calloso-marginal fissure, 226
Canal, alimentary, 260
anal, 276

for Arnold's nerve, 61
auditory, external, 364
carotid, 38
central, of cord, 241
crural, 383
dental, 44, 56
femoral, 383
Haversian, 18
of Huguier, 36, 367
hyaloid, 354
infraorbital, 45
inguinal, 381
for Jacobson's nerve, 01
malar, 64

medullarv, of humerus, 95
of neck, 336
palatine, 52
of Petit, 355
portal, 282
sacral, 76
of Sclilemm, 350
semicirciihir, 373
spiral, 374
of Stilling, 354
for tensor tvmpani muscle,
of tibia, 110
Vidian, 34
of Wirsung, 284
Canal iculi of bone, 18

lacrimal, 361
Canalis centralis modioli, 374
cochlea', 377
hypoglossi, 30
rcuniens, 377
(Cancellous tissue of bone, 18
Canine teeth, 261
Can Hi us of eye, 359
Capillaries. 187
Capsular ligament. 119
of hip, 1.32
of ossicles, 369
Capsule «»r I'.owman, 313

61

Capsule of Glisson, 276, 279, 281
of lens, 3.54
of Tenon, 345
Capsules, suprarenal, 288
Caput coli, 274

gallinaginis, 322
Cardia of stomach, 270
Cardiac incisure, 305
nerve, inferior, 257

superior, 256
plexus, great, 258

superficial, 2.59
veins, 220
Carotid artery, common, 190

surgical anatomy, 211
internal, 193
canal, 38
plexus, 2.57
Carpal articulations, 130

bones, 102
Carpo-metacarpal articulations, 131
Cartilage arytenoid, 296
cricoid, 295
thyroid, 295
Cartilages, costal, 83
cuneiform, 297
of larynx, 295
of Santorini, 297
tarsal, 360
of Wrisberg, 297
Caruncula lacrimalis. .361
Carunoulfe myrtiformes, .333
Cauda ec^uina, 2.56
Caudate nucleus. 2.30
Cavernous groove, 32

plexus, 2.57
Cavities of bones, 21, 22

orbital, 61
Cavity, sigmoid, 99, 100
Cavum Meckelii, 244
Cecum, 274
Celiac axis, 201
Cells of Dieters, 379

gustatory, 343
Cement of tooth, 261
Center of ossification, 20
Central loJ>e, 22()
Cerebellum. 23fi

arrangement of grav matter of,

237
lobes of, 236
peduncles of, 235, 237
sulci of. 23(»
Cerebral arteries, 194

396

INDEX.

Cerebral fissures, 225

fossa, ]ioslerior, 60

Ibssai, ry6

lobes, 225
Cerebrospinal fluid, 240
Cervical ganglia, 25G, 257

plexus, 248
Cervicalis ascendens, 153
Cervix uteri, 334
Chambers of eye, 354
Check ligament, 121
Chondrigen, 17

Chondro-sternal articulations, 123
Chorda tympani, 2(i(), 370
Chorda; tendine?e, 184
Choriocapillaris, 349
Choroid, 348

plexus, 232
Cilia. 360
Ciliary arteries, 357

body, 349

ganglion, 244

muscle, 349

nerve, 358

processes, 349
Circle of Willis, 194
Circulus arteriosus, 349

venosus, 340
Circumferential lamellfe, 19
Circumflex artery, anterior, 198
posterior, 198

nerve, 250
Circum vallate papillae, 266
Clavicle, 89

development of, 91

muscular attachmeuts of, 91
Clinoid processes, 32
anterior, 34
Clitoris, 332
Clivis, 237
Coccygeal ganglion, 256

nerves, 256
Coccygeus, 388
Coccyx, 77
Cochlea, 374

membranous canal of, 377
Cochlear nerve, 379, 380
Collateral fissure, 226
Colles' fascia, 388, 389
Colliculus nervi optici, 352
Colon, 274

ascending, 275

descending, 275

transverse, 275

Columnfc carncpe, 184
(Jolumns of liertin, 313

of spinal cord, 240

of vagina, 334
Commissures, cerebral, 230
Communicans fibularis, 254

peronei, 254, 255
Comjjact tissue of bone, 18
CompU'XUS, 154
Compressor narium minor, 144

nasi, 144

urethra, 388
Concentric lamella^, 18
Concha, 363

Condylar foramen, anterior, 30
l)osterior, 29

fossa, posterior, 29
Condvles, 21

of femur, 108
Condyloid foramen, anterior, 61
posterior, 61

process, 54
Con e-gran u 1 es, 353
Cone-foot, 353
Cone of ligbt, 365
Coni vasculosi, 328
Conjoined tendon, 156
Conjunctiva, 360
Conoid tubercle, 90
Constrictor muscles of pharynx, 268

urcthrfe, 388
Con us arteriosus, 184

medullaris, 240
Convolutions of brain, 226
Coraco-bracbialis, 162
C'oracoid process of scapula, 93
Cornea, 347, 348
Cornicula laryngis, 297
Cornua of cord, 240

of hyoid bone, 78
Corona glandis, 326
Coronal suture, 25, 57
Coronary arteries, 189

artery of stomach, 201

ligaments of liver, 278

plexus, 259

sinus, 270

valve, 183
Coronoid fossa, 54, 56, 97

process, 99
Corpora albicantia. 229

cavernosa, 325

quadrigemina, 233

striata, 230

INDEX.

397

Corpus Arantii, 184

callosum, 231, 232

dentatum, 237

fimbriatum,232

Highmori, 327

luteuiu, 338

S{)ongiosum, 325
Corpuscles, Paciuian, 341

tactile, 341
Corrugator supercilii, 142
Corti, ganglia of, 380

membrane of, 378

organ of, 378

rods of, 378
Cortical substance of kidney, 313
Costal cartilages, 83
Costo-central articulations, 122
Costo-clavicular line, 310
Costo-transverse articulations, 123
Costo-vertebral articulations, 122
Cotyloid cavity, 83

ligament. 133

notcb, 83
Cowper's glands, 324
Cranial ganglia, 244

nerves, 241

topography, 237
Cranium, bones of, 22
Cremaster muscle, 328
Cremasteric artery, 330

fascia, 382
Crest of the ilium, 85

of tibia, 110
Cribriform plute of ethmoid bone,

40
Crico-arytenoideus lateralis, 299

posticus, 299
Cricoid cartilage, 295
Crico-thyroideus, 299
Crista falciformis, 379

galli, 40

vestibuli, 373
Crown of tooth, 200
Crucial ligament, 121, 134, 135
Crura of penis, 325
Crural arch. 385

canal, 383

boundaries of, 384

nerve, anterior, 253
parts around, 384

ring, 384

sheath, 385
Crureus, 172
Crus cerel)ri, 229

Crypts of Lieberkuhn, 274
Crystalline lens, 354

structure of, 355
Cuboid bone, 114
Culmen, 237
Cuneate lobe, 228
Cuneiform bone, 103, 114

cartilages, 297
Cupola of cochlea, 374
Curvatures of stomach, 270
Curved line, 28
Cutaneous nerves of arm, 250
Cuticle, 341
Cystic duct, 282

Daetos, 327
Darwin, tubercle of, 364
Decussation of pyramids, 235
Dtitoid, 161

tubercle, 90
Demours, membrane of, 348
Dental canal, 44

inferior, 56

groove of Goodsir, 263

papilla, 263

ridge, 263

fissure, 226
Dentate nucleus, 235
Dentinal fibers, 263

tubes, 261

tubules, 263
Dentine, 261
Dej^ressor alje nasi, 144

anguli oris, 144

labii inferioris, 144
Derma, 341

Descemet, membrane of, 348
Descending colon, 275
Diagonal line, 108
Diameters of pelvis, 89
Diai)hragni, 160
Diaplivsis, 22
Diartlirosis, 117, 118
Digastric fossa, 36

muscle, 147
Digestive organs, 259
Digital depressions, 35

fossa, 108
Dilator naris anterior, 143
posterior, 143

pupilhe, .351
Discus ])roligerus, .338
Dorsal is pedis artery, 210
Dorsi-spinal veins, 217

398

INDEX.

Dorso-lumbar nerve, 2o2
Dorsum sclhe, .'W
Douglas's poucl), ;>.'>4
Duct of Biutholin, 2G4

common bile-, 282

cystic, 282

ejaculiitory, 331

of Gartner, 339

hepatic, 281

lacrimal, 361

lymphatic, right, 221

nasal, 362

pancreatic, 284

of Eivinus, 265

Stensen's, 265

thoracic, 221

thj'^ro-glossal, 266

Wharton's, 265
Ductless glands, 284
Ductus cochlearis, 377

communis choledochus, 282

endolymphaticus, 373
Duodenum, 272
Dura mater, 240

cerebral, 222

sinuses of, 214

Ear, 363

external, 363

internal, 372

middle, 365
Ear-point, 364
Ear-stones, 376
Eighth nerve, 246
Ejaculatory duct, 331
Elbow-joint, 128
Eleventh nerve, 247
Eminence of aqueductus Fallopii,
367

ilio-pectineal, 87
Eminentia arcuata, 38, 60

articularis, 35

collateral is, 231
Emissary veins of Santorini, 214
Emulgent vein, 316
Enamel cells, 263

columns, 261

membrane, 263

organs, 263

pulp, 263

of tooth, 261
Enarthroses, 118
Endocardium, 186
Eudolymph, 375

Endosteum, 19
Ensiform cartilage, 80
Epenceidialon, 224
Epicondyle of femur, 109

of humerus, 96
Epidermis, 341
Epididymis, 328
Epigastric artery, deep, 205
superficial, 208
superior, 196
region, 290
Epiglottis, 297

muscles of, 300
Epiphysis, 22

cerebri, 233
Equator of eye, 345

of lens, 354
Equatorial plane of eye, 345
Erectile tissue, 326
Erector clitoridis, 387
penis, 387
spinse, 152
Esophageal artery, 200
Esophagus, 269
Ethmoid bone, 40

articulations of, 42
centers of ossification of, 42
cells, 41

process of inferior turbinated,
52
Ethmoidal canals, 25
foramen, 64
foramina, 58
notch, 24
spine, 31
Ethmo-sphenoidal suture, 64
Eustachian tube, 371

opening of, 368
valve, 183
Exoccipitale, 27
Extensor brevis digitorum, 179
hallucis, 179
pollicis, 167
carpi radialis longior, 165

ulnaris, 166
coccygis, 155

communis digitorum, 166
indicis, 167
longus digitorum, 175
hallucis, 175
pollicis, 167
minimi digiti, 166
ossis metacarpi pollicis, 166
External capsule, 230

INDEX.

399

External ear, 363

oblique muscle, 156
Eye, 345

appendages of, 359

coats of, 346

nerves of, 358
Eyeball, 345

muscles of, 355
Ej'ebrows, 359
Eyelashes, 360
Eyelids, 359

Facial artery, 192

nerve, 246
Falciform ligament of liver, 277,278

process of Burns, 384
Fallopian tubes, 337
False pelvis, 88

ribs, 80

vertebrae, 69
Falx cerebelli,223

cerebri, 2:22
Fang of tooth, 260
Fascia, Buck's, 389

Colics', 3«8, 389

cremasteric, 382

dentata, 232

infundibuliform, 328

intercolumnar, 328

lata, 170

lumbar, 158

palmar, 167

pelvic, 389

plantar, 179

recto-vesical, 389
Fasciae, 141

of foot, 178

of hand, 167

perineal, 388
Fasciculus teres, 334
Fauces, pillars of, 264
Female generative organs, 331

perineum, 390

urethra, 323
Femoral artery, 206

common, surgical anatomy,
213

canal, 383

hernia, anatomy of, 383
coverings of, 385

ring, 384

superficial, surgical anat-
omy, 213
Femur, lOG

Femur, development of, 109

muscular attachments of, 109
Fenestra oval is, 367, 373

rotunda, 367
Fibula, 112
Fibular nerve, 255
Fifth nerve, 243

ventricle, 233
Filiform papillae, 266
Filum termiuale, 240
Fimbriae of oviduct, 337
First nerve, 241
Fissure, auricular, 39
calcarine, 226
calloso-marginal, 226
collateral, 226
dentate, 226
Glaserian, 35, 61, 367
of liver, 278
longitudinal, 228
of liver, 278
palpebral, 359
parieto-occipital. external, 225

internal, 226
petro-tympanic, 367
pterygomaxillary, 69
of Eolando, 225

location of, 238
sphenoidal, 60. 64
spheno-maxillary, 64, 68
of Sylvius, 225

location of, 238
transverse, 226

of liver, 278
umbilical, 278
Fissures, cerebral, 225
of spinal cord, 240
Flat bones, function of, 21
Flexor accessorius, 180
brevis digitorum, 179
hallucis, ISO
minimi digiti, 169, 181
pollicis, 168
carpi radialis, 163

ulnaris, 164
longus digitorum, 177
hallucis, 177
pollicis, 165
]»rofundus digitorum, 164
siiblimis digitorum, 164
Fhmting ril)S, 80
Flocculus, 2'.i7
Fhjod's ligament, 127
Folds of Houston, 276

400

INDEX.

Folium cacuniinis, 237
Fontana, spaces of, 350
Fontanels, 58
Foot, bones of, 113

muscles of, 179
Foramen for Arnold's nerve, 38

caicum, 58, 2UG

of frontal bone, 24

centrale cocbleai, 380

condj'lar, anterior, 61
posterior, 29

condyloid, posterior, 61

ethmoidal, 58, 64

intervertebral, 70

for Jacobson's nerve, 38, 367

jugular, 38

lacerum medium, 60
posterius, 30, 61

magnum, 29, 61

of Majendie, 240

malar, 49

mastoid, 36, 61

medullary, 90, 99
of femur, 108
of radius, 100

mental, 55

of Monro, 232

obturator, 84

optic, 34, 66

ovale, 60

of sphenoid, 33

parietal, 26

rotundum, 32, 60

sacral, 75, 76

of Scarpa, 47

singulare, 379

spheno-palatiue, 51, 67

spinal, 72

spinosum, 33, 60

of Stensen, 47

stylo-mastoid, 39, 61

supra-orbital, 23, 65

thyroid, 84

Vesalii, 33, 60

of Winslow, 293
Foramina Thesbesii, 183
Forearm, bones of, 97

muscle of, 163
Fornix, 232

conjunctivfe, 360
Fossa, anterior, of skull, 58

of antihelix, 363

canine, 44

capitis, 106

Fossa, cerebral, 58

coronoid, 97

digastric, 36

digital, 108

glenoid, 94

of helix, 363

iliac, 85

incisive, 44

infraorbital, 45

infraspiuous, 91

ischio-rectal, 385

jugular, 30

lacrimal, 24, 63

nasal, 66

uavicularis, 322
female, 333

olecranon, 97

ovalis, 183, 384

patellaris, 354

pterygoid 34

of Rosenmiiller, 268

scaphoidea, 363

of skull, anterior, 58
middle, 60

sphenomaxillary, 69

subarcuate, 61

sublingual, 55

submaxillary, 56

subscapular, 91

suprasjtinous, 91

temporal, 67

triangularis, 296

trochlear, 24

vesicalis, 278

zygomatic, 68
Fourchette, 333
Fourth nerve, 242

ventricle, 234
Fovea centralis, 352

hemielliptica, 373

hemispherica, 373
Frenum linguae, 266

preputii, 326
Frontal bone, 22

articulations of, 25
centers of ossification of, 25
muscles from, 25

crest, 24

eminences, 23

lobe, 225

process, 49

sinuses, 23, 25

sulcus, 24
Fron to-malar suture, 64

INDEX.

401

Fronto-parietal suture, 57
Frouto-sphenoidal suture, 64
Fuudameutal laniellai, 19
Fungiform pai>illa?, 266
Fuuiculus cuueatus, 235

gracilis, 235

of Rolando, 235

Gaertnek, duct of, 339
Gall-bladder, 282
Ganglion, Arnold's, 244

of Bochdalek, 244

cervical, 256, 257

ciliary, 244

coccvgeal, 256

of Corti, 380

Gasserian, 243, 244

impar, 256

otic, 244

of Ribes, 256

spheno-palatine, 244

spirale, 375, 380

submaxillary, 245

of Valentin^ 244
Gangli<mic layer of retina, 352
Gasserian ganglion, 243, 244
Gastric artery, 201
Gastrocnemius, 176
Gastro-colic omentum, 293
Gastro-hepatic omentum, 293
Gastro-splenic omentum, 294
Gemellus inferior, 174

superior, 174
Generative organs, female, 331

male, 324
Genial tubercles, 55
Geniobyoglossus, 147
Geniobyoid muscle, 1 17
Genitocrural nerve, 253
Germinal spot, 338

vesicle, '.V.iH
Gimbernat's ligament, 156
Ginglvmus, 118
GhibeJbi, 23, 237
(iladiolus, 80
(iland, lacriinal, 361

lingual, 2(56

mammary, 339

l>arotid, 264

j)n)statc, 324

sublingual, 265

submaxillary, 2()5

tbymiis, 287

thyroid, 286

20

Glands of Bartholin, 333

Brunner's, 274

Cowper's, 324

ductless, 284

of Littre, 323

Meibomian, 360

of Moll, 360

parathyroid, 287

Peyer's, 274

salivary, 264

sebaceous, 342

solitary, 274

sweat-, 342

Tyson's, 326
Glandulse Tysonii odoriferae, 326
Glans penis, 326
Glaserian fissure, 35, 61, 367
Glenoid fossa, 35, 94

ligament, 127
Glisson, capsule of, 276, 279, 281
Glosso-ei)iglottic folds, 297
Glosso-pharyngeal nerve, 247
Glottis, 298
Gluteal artery, 205

lines, 85

nerves, 254
Gluteus maximus. 173

medius, 173

minimus, 173
Gomphosis, 118
Graafian follicles, 337, 338
Gracilis, 172

Groove, auriculo-veutricular, 182,
183

bicipital, 95

infraorbital, 64

sacral, 76

spiral, 95

sub(;lavian, 90
Gubernaculum testis, 331
(Gustatory cells, 343

pore, 343
Gyri 226
Gyrus fornicatus, 226

HAiR-bulb, :i42

H<air-('(lls of ('orti's organ, 378

Hair-follicle, 312

Hair-pa|)illa, 342

Hairs, 341

Hammer, MM

Hamstring, inner, 175

outer, 174
Hamular process, 34, 48, 375

402

INDEX.

Hand, bones of, 102

iasciaj of, 1(J7

muscles of, 1G8
Hard palate, 2t)3
Hasiier, valve of, 3(32
Haversian canals, 18

system, 18
Head, hones of, 22

of bone, 21

of femur, 10()

of fibula, 112

of humerus, 95

muscles of, 142

of radius, 10©

of rib, 81

of tibia, 110

veins of, 214
Heart, 182

structure of, 186

veins of, 220
Helicine arteries, 326
Helicis major, 364

minor, 364
Helicotrema, 374
Helix, 363
Hemiarthrosis, 117
Henle's looj), 313
Hensen's line, 140
Hepatic artery, 202, 281

duct, 28l"

veins, 280
Hepato-duodenal ligament, 293
Hernia, femoral, anatomy of, 383

inguinal, anatomy of, 381
Hesselhach's triangle, 383
Hey's ligament, 384
Hiatus Fallopii, 38, (JO
Highmore, antrum of, 43, 46
Hilum of kidney, 313

of liver, 278

of lung, 304

of spleen, 285
Hii)-joint, 132
Hippocampus major, 231
Histology, definition of, 17
Horizontal i)late of palate bone, 52
Horner's muscle, 142
Houston's folds, 276
Huguier, canal of, 86, 367
Humerus, 95

development of, 97

muscular attachments of, 97
Humors of eye, 346, 354
Hunter's canal, 172

Hyaloid canal, 354

membrane, 354
Hydatids of Morgagni, 329
Hymen, 333
Hyoglossus, 148
Hyoid bone, 78

Hypochondriac regions, 290, 292
Hypogastric artery, 204

plexus, 259

region, 291
Hypoglossal nerve, 248, 267

Ileo-cecal valve, 273
Ileum, 273
Iliac artery, 204

common, 203

surgical anatomy, 212
deep circumflex, 206
external, 205
internal, 203

surgical anatomy, 213
superficial circumflex, 208

fossa, 85

vein, common, 219
internal, 219
Iliacus, 170
Ilio-costalis, 152
Ilio-fcniorul ligament, 132
Ilio-hypogastric nerve, 252, 253
Ilio-inguinal nerve, 253
Ilio-lumbar, artery, 205
Ilio-pectineal eminence, 87

line, 87
Ilio-tibial band, 170
Ilium, 85

Impression, rhomboid, 91
Incisive fossa, 44
Incisor crest, 47

fossa, 55

teeth, 261
Incisura cerebelli, 236

intertragica, 363
Incus, 368

Inferior curved line, 28
Infracostales, 159
Infraorbital artery, 357

groove, 45, 64
Infras|)inatus, 162
Infraspinous fossa, 91
Infratemporal ridge, 33
Iiifnndibula of lungs, 307
Infundibuliform fascia, 328
Infundii)ulum, 229

of cochlea, 374

INDEX.

403

Inguinal canal, 381

boundaries of, 382
hernia, anatomy of, 381
external oblitjue, 383
internal or direct, 383
regions, 290, 292
Inion, 237

Innominate artery, 189
bone, 83
veins, 216
Insertion of muscle, 141
Interclavicular notch, 80
Intercolumnar fascia, 328
Intercostal arteries, 201
superior, 196
muscles, external, 159
internal, 159
Interlobular arteries, 315

veins, 280
Intermediate disk, 140
Internal capsule, 230
ear, 372

oblique muscle, 156
Interossei, dorsal, 169
of foot, 181
palmar, 169
plantar, 181
Interosseous border, 100
ligament, 125

of carpus, 131
membrane of arm, 130

of leg, 136
nerves of arm, 251
ridge, 110
Interparietal bone, 27

suture, 57
Interphalangeal articulations, 132
Inters])inales, 155
Interstitial lamellse, 18
Intertransversalcs, 155
Intertrochanteric lines, 108
Intertubular substance, 261
Intervertebral fibrocartilage or disk,
119
foramina, 70
Intestine, large, 274

blood- and nerve-supply of,
276
small, 272

blood-vessels of, 274
coats of, 273
glands of, 274
iM'rv(!S of, 274
Intumescentia gangliaformis, 380

Iris, 350

Ischio-cavernosus, 387
Ischiorectal fossa, 385
Ischium, 86
Isthmus faucium, 264

of thyroid, 86

tubfe, 371
Iter chordai anterius, 367
posterius, 367

Jacob's membrane, 353
Jacobson's nerve, 370
Jejunum, 273

Joints, nerve-supply of, 119
Jugular foramen, 38

fossa, 30, 38

notch, 29

process, 29

veins, 215

Kerato-cricoideus, 300
Kidney, 312

nerves of, 317

relations of, 312

size and weight, 312
Knee-joint, 133
Krause's membrane, 140

Labia majora, 332

minora, 332
Labyrinth, 372

membranous, 375

osseous, 372
Lacrimal appa vatus, 361

artery, 357

bones, 48

canal, 46, 48

canaliculi, 361

ducts, 361

fossa, 24, 63

gland, 361

nerve. 358

notcli, 45

papilla^ 360

process of inferior turbinated,
52

sac, 362

tubercle, 46
Lacrimo-ethmoidal suture, 64
Lac teals, 220
Lacuna magna, 323
Lacunic of l)one, 18
Lacus hicrimalis, 360
Laml)da, 237

404

INDEX.

L:iiub(l(»i(l suture, 25, 57
Lamellct; of bone, 18

circuuiferential, 19

concentric, IW

fundamental, 19

interstitial, 18
Lamina cinerea, "228

cribrosa, 38, 347, 372, 379

fossa, 347

recticularis, 379

spiralis, 375

suprachoi'oidea, 348

terminal is, 229

vitrea, 349
Lamime of vertebra, 71
Large intestine, 274
Laryngeal nerve, 256. 301

'poucb, 299
Larynx, 295

arteries and veins of, 300

cartilages of, 295

ligaments of, 297

muscles of, 299

nerve-supply of, 301

ventricle of, 299
Lateral ligaments of liver, 278

masses of ethmoid bone, 41

ventricles, 231
Latissimus dorsi, 150
Left auricle, 184

ventricle, 185
Leg, muscles of, 175
Lens, crystalline, 354
Lenticular nucleus, 230
Levator anguli oris, 144

ani, 3S7

glandulpe thyroidese, 286

labii inferioris, 144
superioris, 144

alseque nasi, 143

palati. 148

palpebrse superioris, 142

scapulae, 150
Levatores costarum, 159
Ligament, annular, anterior, 167
of foot. 178
external, of foot, 179
internal, of foot, 178
posterior, 167
of wrist, 130

anterior, of ankle. 137
common. 119
of elbow, 128

atlanto-axial, 120

Ligament, Vjroad, of liver, 277

of uterus, 3.35
calcaneo-astragaloid, 137
calcaneo-cuboid, 138
calcaneo-navicular, 138, 139
capsular, 119

of hip, 132

of ossicles, 369
check, 121

chondro-clavicular, 126
cbondro-sternal, 123
chondro-xiphiod, 124
coraco-acromial, 127
coraco-clavicular, 127
coraco-humeral, 127
coronary, of liver, 278
cotyloid, 133
crucial, 120. 134, 135
deltoid, 137

falciform, of liver, 277, 278
Flood's, 127
Gimbernat's, 156
gleno-humeral, 127
glenoid, 127
hepato-duodenal, 293
Key's, 384
ilio-femoral, 132
ilio-luniV»ar, 124
infraspinous, 119
interclavicular, 126
interosseous, 125

of corpus, 131
intertransverse, 119
long internal lateral, 122
oblique, of arm, 130
obturator, 126
occipito-atlantal, 120
occi pi to-axial. 121
occi pi to-cervical, 121
occipito-odontoid, lateral, 121
orbicular, 129
phreno-colic, 285
posterior, of ankle, 137

common, 119

of elbow, 128
Pou part's, 156, 170, 382
pubo-prostatic, 319
radio-carpal, 1.30
radio-ulnar, 129
r(>cto-uterine. 335
rhomboid, 126
round, of liver, 278

of uterus, 336
sac lo coccygeal, 125

INDEX.

405

Lij^ament, sacro-iliac. 125
sacro-luin])ar, 124
sacro-sciatic, 12.")
short internal lateral, 122

vertebral, 119
spheno-mandibular, 122
spino-glenoid, 127
stellate, 123
stylo-maxillary, 122
suprapubic, 126
supraspinous, 119
suspensory, of incus, 369
of lens, 355
of liver, 277, 278
of malleus, 368
of penis, 325
of si)leen, 2S5
thyro-epis^lottic, 297
tibio-fibular, 136
transverse, of hip, 133
of knee-joint, 135
trapezoid, 127
triangular, 389
vesico-uterine, 335
of Wrisberg, 135
Y-, 132
Ligamenta alaria. 135
Ligaments of bladder, 319
intersternal, 124
lateral, of liver, 278
of larynx, 297
of ossicles, 368
palmar, 131
of scapula, 127
of Schlemin, 127
of sternum, 124
tarsal, 360
of uterus. 335
Ligamentum arcuatum, 134
externum, 158
denticiilatnm, 240
latum pulmonis, 308
mucf)sum, 135
nuclue, 150
patellfE, 134

pectinntum iridis, 348, 350
spirale, 378
subflavum, 119
suspensorium, 122

oculi, 346
t'-ris. 133
Winslowii. 134
I>iml)ic IoIk;, 227
Limbus laminte spiralis, 377

Line, diagonal, 108
Hensen's, 140
ilio-pectirieai, .'-7
intertrochanteric, 108
Linea alba, 156
aspera, 108
axillaris, 310
eminens, 296
niammillaris. 310
mediana, 310
parasternalis 310
quadrat i, 108
scapularis, 310
splendens, 240
sternalis, 310
stern o- costal is, 310
Lingual arterv, 191
glands, 206
lobule, 305
nerves, 266
tonsil, 266
Lingualis, 148
Lingula, 233, 237
Liquor folliculi, 338

Morgagni. 355
Lisfranc's tubercle, 82
Lithotomy, i)arts divided in, 390
Liver, 276

blood-vessels of, 279
lobes of, 279
nerves of, 281
relations of, 282
structure of, 281
Lobes of cerebellum, 236
of cerel)rum, 225
of liver. 279
Lobus caudatus, 279
centralis, 237
quad rat us, 279
Spigelii, 279
Locus cffruleus, 234
I Long bones, 20
, Longissimus dorsi, 153
I Longitudinal fissure, 228
' Longus colli, 1 19

Lower extremity, veins of, 218
' Lower, tubercle of, 183
j Lumbar arterv, 203 .
t fjiscia, 158

I nerves, 252

plexus, 252
I regions, 290, 292

Liimbo-sacral cord, 252
Lumbricales, l(i9, 180

406

INDEX.

Lungs, 303

structure of, 300

toi)ognii)hical anatomy of, 309

vessels and nerves of, 307
Lunula of nail, 341
Lvni]>liatic duct, right, 221

glands, 220
Lynii)liatics, 220
Lvniph-spaces of eyeball, 358
Lyra, 232

Macula acustica, 376

lutea, 351
Malar bone, 49
canal, (J4
foramina, 49
process of superior maxillary,

46
tuberosity, 49
Male generative organs, 324

urethra, 321
Malleolus, external, 112

internal, 110
Malleus, 368

Malo-maxillary suture, 64
Malpighian bodies, 236
body, 315
tuft, 313, 315
Mam m 06, 339

Mammayy artery, accessory exter-
nal, 198
internal, 196
glands, 339

vessels and nerves of, 340
Mandible, 54
Manubrium, 80

of malleus, 368
^larginal convolutions, 226
Marrow of bone, 19
Masseter, 145

Mastoid antrum, location of, 238
cells, 36
foramen, 36, 61
portion of temporal bone, 36
process, 36
Masto-occipital suture, 57
Masto-parietal suture, 57
Matrix of nail* 341
Maxillary bane, inferior, 54

articulation of, 56
centers of ossification

of, 56
muscular attachment
of, 57

Maxillary bone, superior, 43

articulations of, 48
centers of ossification

of, 48
muscular attachments
of, 48
nerve, inferior, 243

superior, 243
process, 49, 51

of inferior turbinated, 52
sinus, 46
tuberosity, 44
Meatus auditorius externus, 37
internus, 38, 60
of nose, inferior, 67
middle, 67
superior, 67
urinarius, 323, 326
female, 332
Meatuses of the nose, 67
Median nerve of arm, 250
Mediastinal artery, posterior, 201
Mediastinum, 303

testis, 327
Medulla of bone. 19

oblongata, 235
Medullary artery, 19, 21, 198
canal of bone, 18
of humerus, 95
of tibia, 110
foramen, 90, 99
of femur, 108
of radius, 100
substance of kidney, 313
Medulli-spinal veins, 2i8
Meibomian glands, 360
Membrana basilaris, 377, 378
fiaccida, 365
granulosa, 338
limitans interna, 352
pupillans, 351
tectoria, 378
tympani, 365

secondaria, 367
Membrane of Bowman, 348
of Bruch, 349
of Descemet, 348
hyaloid, .354
. of Corti, 378
interossous, 130
Jacobs', 353
Krause's, 140
of Miiller, 353
of Reissuer, 377

INDEX.

407

Membrane, Schneiderian, 343

Schrapiieirs, 365

vitelline, 338
Membranous canal of cochlea, 377

labyrinth, 375

urethra, 322
Meningeal artery, middle, location

of, 238
Meningo-rachidian veins, 218
Mental foramen, 55

process, 55

tubercle, 55
Meridional plane of eye, 345
Mesencephalon, 224
Mesenteric artery, inferior, 202

superior, 202
Mesenteries, 294
Mesocecum, 294
Mesocolon, 294
Mesogastrium, 294
Mesorectum, 275, 294
Metacarpal bones, 104
Metacarpo-phalangeal articulations,

132
Metatarsal artery, 210

bones, 114
Metatarsus, synovial sacs of, 139
Metencephalon, 224
Middle ear, 365

fossa of skull, 60
Milk teeth, 260
Mitral valve, 182, 185
Modiolus, 374
Molar teeth, 261
Moll, glands of, 360
Monro, foramina of, 232
Mons Veneris, 332
Motor oculi, 242
Mo to rial end-plates, 222
Mouth, 263

Miiller, membrane of, 353
Multifidus spinai, 155
Muscle, 140

ciliary, 349

Homer's, 142

intercostal. 159

origin and insertion of, 141
Muscles of abdomen, 15()

of ba<;k, 150

of ei)iglottis, .300

of Eustachian tube, .371

of fixternal ear, 364

of cvcball, .355

of foot, 179

Muscles of forearm, 163
of hand, 168
of head, 142
of larynx, 299
of leg, 175

of lower extremity, 169
of neck, 145
of perineum, 386
of shoulder and arm, 161
of thorax, 1.59
of tympanum, 369
of ureters, 320
vertebral, 149
Muscular nerve of brachial plexus,
250
of internal popliteal, 254
of posterior tibial, 255
of sacral plexus, 254
tissue, varieties of, 140
Musculi papillares, 184

pectinati, 183
Musculo-cutaneous nerve of arm,

250
Musculo-phrenic artery, 196
Musculo-spiral nerve, 251
Musculus accessorius ad iliocosta-
lem, 1.53
of leg, 255
Mylohyoid groove, 56
muscle, 147
ridge, .56
Myrtiform fossa, 44

Nails, .341
Nares, 66
Nasal bones, 43

crest, 47

duct, 362

eminence, 23

fossae, 66

blood-vessels of, 344

meatus, 42

mucous membrane, 343

notch, 23

process, 23

of superior maxillary, 46

septum, 67

spine, 23

anterior, 47
l)osterior, 52
Nasi on, 237

Naso-|)aIatine groove, .54
Navicular bone, 114
Neck of femur, 106

408

INDEX.

Neck, muscles of, 145

of rib, 81

of tooth, 260

veins of, 214

Nerye, abducens, 24G

articular, of internal popliteal,

254
auditory, 246, 379
cardiac, inferior, 257

superior, 256
ciliary, 358
circumflex, 250
cochlear, 380, 379
crural, anterior, 253
cutaneous, of arm, 250
dorso-lumbar, 252
eighth, 246
eleventh, 247
facial, 246
fibular, 255
fifth, 243
first, 241
fourth, 242
genito-crural, 253
glosso pliaryngeal, 247
gluteal, 254
hypoglossal, 248, 267
ilio hypogastric, 252, 253
ilio-inguinal, 253
interosseous, of forearm, 251
Jacobson's, 370
lacrimal, 358
laryngeal, 256
lingual, 266
maxillary, inferior, 243

superior, 243
median, of arm, 250
muscular, of internal jtopliteal,
254

of posterior tibial, 255
musculo-cutaneous, of arm, 250

of leg, 255
musculo-spiral, 251
ninth, 247
obturator, 253
olfactory, 24 J. 344
ophthalmic. 243
optic, 241, 358
petrosal, 245
pharyngeal, 256
phrenic, 249
plantar, 255
pneumogastric, 247
popliteal, external, 255

Nerve, popliteal, internal, 254

pudic, 254

radial, 251

sacral, 256

sciatic, 254

second, 241

seventh, 246

sixth, 246

spinal accessory, 247

splanchnic, 258

subscapular, 250

suprascapular, 250

sympathetic, 256

tenth, 247

third, 242

tibial, anterior, 255
posterior, 255

trifacial, 243

trochlear, 242

twelfth, 248

tympanic, 370

ulnar, 251

vagus, 247

vestibular, .380

Vidian, 345

of Wrisberg, 250
Nerve-fiber layer, .3.52
Nerve-tissue, structure of, 221
Nerves, coccygeal, 256

cranial, 241

of auricle. 364

of bladder, 321

of choroid, 349

of Eustachian tube, 372

of eye, .358

of eyelids, .360

of iris, 351

of kidney, 317

of Lancisi, 2.32

of larynx, 301

luuibar, 2.52

of lungs, .308

of mamma". 340

of membrana tympani, 366

of nose, 344

of ocular muscles, 357

of penis, 327

spinal, 248

of testicle. .3.30

tlioracic, 2.52

of trachea. .303

of tympanum, .370

of uterus, .337
Nervous system, 221

INDEX.

409

Nervus fuscalis, 252

Xeuri lemma, 222

Ninth nerve, 247

Nipple, 339

Nodal point, 345

Nodulus, 237

Nose, blood-vessels of exterior, 343

nerves of, 344
Notch, cotyloid, 83

interclavicular, 80

popliteal, 110

of Rivinus, 3(J5

sacro-sciatic, greater, 85

supra-orbital, 23

suprascapular, 94
Notches, vertebral, 70
Nucleus amygdalse, 230

caudate, 230
Nymphse, 332

Obex, 234

Oblique line of clavicle, 90
external, 55
internal, 56
of scapular, 91
Obliquus auris, 304

capitis inferior, 156

superior, 156
inferior, 356
superior, 356
Obturator artery, 204
externus, 174
foramen, 84
internus, 174
ligament, 120
nerve, 253
Occipital artery, 192
bone, 27

articulations of, 30
centers of ossification of, 31
crest, internal, 30
groove, 36
lobe, 220
protuberance, external, 28

internal, 30
sinuses, 30
Occipito-atlantal articulation, 119
Occipto-frontalis, 142
Ofr'ii»ito-pari(!tal suture, 57
Odontoblasts, 202
Olecrajion fossa, 97

process, 99
Olfactory l)ulbs, 232

cells of Scliultze, :i43

Olfactory grooves. 31, 40

nerve, 241, 344
Olivary body, 235

process, 32
Omentum, gastro-colic, 293

gastro-hepatic, 293

gastro-splenic, 294

great, 293

lesser, 293
Omo-hyoid muscle, 147
Opercula, 226
Ophthalmic artery, 194, 357

nerve, 243
Opponens minimi digiti, 169

poUicis, 108
Optic chiasm, 242

commissure, 228

foramen, 32, 34, GG

groove, 31

nerve. 241, 358

origin and course of, 359

thalamus, 230

tracts, 359
Ora serrata, 351
Orbicular ligament. 129
Orbicularis oris, 144

palpebrarum, 142, 360
Orbital cavities, 01

foramina, external, 34

lobe, 225

plates, 24

process, 49
Organ of Corti, 378

of Rosen raiiller, 339
Origin of muscle, 141
Os calcis, 113

magnum, 104

orbiculare, 308

planum, 41

unguis, 48

uteri, externum. 335
internum. 335
Osseous labryinth, 372
Ossicles, ligaments of. 308

of tymi)anum. 3(iS
Ossification, center of. 19, 20
Osteoblasts, 19. 20
Osteology, definition of. 17
Ostium abdominale, 337
Otic ganglion, 244
Otocojiia, 370
Otoliths. 370
Outh't of jMdvis. 89
Oval window, 367

410

INDEX.

Ovarian arteries, 339

artery, 203, 33G

nerves, 339
Ovaries 337
Ovicapsule, 338
Oviducts, 337
Ovisacs, 338
Ovoidal facets, 110
Ovula Nabothi, 336
Ovum, 338

Pacchionian bodies, 223

depressions, 26
Pacinian corpuscles, 341
Palatal muscles, 148
Palate bone, 50

center of ossification of, 52

hard, 263

process of superior maxillary,
45, 47

soft, 264
Palatine canal, accessory posterior,
52
anterior, 47
posterior, 44

fossa, anterior, 47
Palato-glossus, 148
Palato-maxillary suture, 64
Palato-pharyngeus, 148
Palinur fascia, 167
Palniaris brevis, 169

longus, 164
Palpebral arteries, 357

fissure, 359
Pampiniform plexus, 330
Pancreas, 283

lesser, 284
Pancreatic duct, 284
Papilla Vateri, 282
Papillfe of tongue, 266
Papillary layer, 341
Paracentral lobe, 228
Parallel fissure, location of, 239
Paramastoid, 29
Parathyroid glands, 287
Parietal bone, 25

development of, 26

eminence, 25

foramen, 26

fossa, 26

lobe, 225
Parietooccipital fissure, external,
225
internal, 226

Paricto-occipital fissure, location of,

23!)
Parotid gland, 264
Parovarium, 339
Pars ciliaris retina, 351, 352

intermedia, 333

iridica retina;, 351

optica retinae, 351
Patella, 109
Patheticus, 242
Pectineus, 172
Pectoralis major, 161

minor, 161
Pedicles of vertebra, 70
Peduncles of cerebellum. 235, 237
Pelvic bones, 83

development of, 88

fascia, 389

plexuses, 259
Pelvis, 88

diameters of, 89

differences between male and
female, 89

of kidney, 313
Penis, 325

blood-vessels and nerves of, 326
Perforated space, anterior, 229

posterior, 229
Perforating fibers of Sharpey, 19
Pericardial arterj", 200
Pericardium, 181
Perilymph, 372
Perimysium, 140
Perineal fasciae, 388
Perineum, 385, 386

female, 390
Perineurium, 222
Periosteum, 19
Peritoneum, 292
Permanent teeth, 260

appearance of, 262
Peroneal artery, 210

bone, 112
Peroneus brevis, 178

longus, 178

tertius, 175
Perpendicular plate of ethmoid

bone, 41
Pes accessor i us, 231
Petit, canal of, 355
Pctro-occipital suture, 57
Petrosal nerves, 245

process, 32
Petro-sphenoidal suture, 57

INDEX.

411

Petro-tym panic fissure, 367
Petrous portion of temporal bone, 37
Fever's glands or patches, 274
Phalangeal processes, 379
Plialaijges, 106

of foot, 117
Pharyngeal artery, ascending, 192

bursa, 268

muscles, 268

nerve, 256

spine, 30

tonsil, 268
Pharyngo epiglottic fold, 297
Pharynx, 267

arteries of, 269

constriction of, 268

nerves of, 269
Phrenic artery, inferior, 202

nerve, 249
Phreno-colic ligament, 285
Pia mater, 223, 240

testis, 327
Pigmentary layer of retina, 353
Pillars of fauces, 264
Pineal gland, 233
Pinna, 363
Pisiform bone, 104
Pituitary body, 229

membrane, 343
Plantar artery, external, 211
internal, 211

fascia, 179

nerves, 255
Plantaris, 177
Platvsma mvoides, 145
PleuVfe, 308 '

topographical anatomy of, 309
Pleural cavity, 308

sinus, 308
Plexus, aortic, 259

})rachial, 249

cardiac, great, 258
superficial, 259

carotid, 257

cavernous, 257

cervical, 248

coronary, 259

hypogastric, 259

lutn1);ir, 252

panipinifonu, 330

renal, :)17

sacral, 253

solar, 25H

tympanic, 370

Plexuses, pelvic, 259
Plica epigastriea, 383

semilunaris, 361

uracil i, 319

ureterica, 321
Pneumogastric nerve, 247
Pons hepatis, 278

Varolii. 234
Popliteal artery, 208

nerve, external. 2.55
internal, 254

notch, 110

space of femur, 108
Popliteus, 177
Porta hepatis, 278
Portal canals, 282

system of veins, 219

vein, 279
Porus opticus, 352
Poupart's ligament, 156, 170, 382
Prtpuce, 326

Primary areolae of ossification, 20
Process, acromion, 92

alveolar, 46

angular, of frontal bone, 23

auditorv, external, 37

basilar,' 29

clinoid, 32

condyloid, 54

coracoid, 9.3

coronoid, 54, 56, 99

ethmoidal, of inferior turbi-
nated, 52

of fibula 112

frontal. 49

hamular, 48. 375

of Ingrassias. 34

laci-imal, of inferior turbinated,
52

malar, 46

mastoid, 36

maxillary. 49, 57

mental, 5.5

nasal, 46

of frontal bone, 23

olecranon, 99

olivary, .32

orbital, 49

palate, 47

pterygoid. 34, 51

si>h('noidal, 51

styhiid, .39. 99, 100

unciform. 41

/.vgoniatic, 35, 49

412

INDEX.

Processes of bone, 21
ciliary, 349
phalangeal, 379
nngnal, 106
vermiform, 23G
of a vertebra, 71
Processns brevis of mallens, 368
cochleariformis, 39, 61, 368
gracilis of malleus, 368
tubae, 34
Profunda cervicis, 197
femoris, 208
inferior, 198
superior, 198
Promontory of sacrum. 76

of tympanum, 364
Pronator quadratus, 165

teres, 163
Prosencephalon, 224
Prostate gland, 324
Pi'ostatic sinus, 322

urethra, 321
Psoas magnus, 169

parvus, 170
Pterygoid fossa, 34

muscle, external, 145

internal, 145
processes, 34, 51
tubercle, 34
Pterygo-maxillary fissure, 69
Pterygo-palatine canals, 32

grooves, 32, 52
Pubes, 87
Pubic spine, 87
Pubo-prostatic ligament, 319
Pudendum, 331

Pudic artery, inferior external, 208
internal, 204
superior external, 208
nerve, 254
Pulmonary artery, 187
semilunar valves, 184
valve, 182
veins, 220
Pulp-cavity, 260
Pulp of tooth, 261
Punctum lacrimale, 360
Pupil, 350
Pylorus, 270
Pyramid of tbyroid, 286

of tympanum, 367
Pyramidal eminence, 373

tracts, 235
Pyramidalis, 158

Pyramidalis nasi, 143
Pyramids of Fi;rrein, 315

of Malpighi, .il'.i

of medulla oblongata, 235
Pyramis, 237
Pyriformis, 173

Quadrate lobe, 227
Quadratus femoris, 174

lumborum, 158
Quadriceps femoris, 172

Radial, artery, 199

nerve, 251
Radio-ulnar articulations, 129
Radius, 100

development of, 100
muscular attachments of, 102
Rami of inferior maxillary bone, 56
Ramus of ischium 87
Recto-uterine ligament, 335

pouch, 335
Recto-vesical fossa, 389
Rectum, 275
Rectus abdominis, 158

capitis anticus minor, 149
posticus major, 155
minor, 155
ex tern us, 356
femoris, 170
inferior, 355
in tern us, 356
lateralis, 149
superior, 355
Red marrow, 19
Regions, abdominal, 290
Reissner, membrane of, 377
Renal artery, 202, 315
circulation, 315
plexus, 317
vein, 316
Restiform bodv, 235
Rete testis, 328
Reticular layer of derma, 341

of retina, 353
Retina, 351

structure of, 352
Retrabens an rem, 142
Rhomboid impression, 91

ligament, 126
Rliomboideus major, 151

minor, 151
Rib, parts of, 81
Ribs, 80

INDEX.

413

Ribs, develoimieut of, SI

false, 80

lloatiug, 80

peculiar, 82

true, 80
Eidge, interosseous, 110

sui)racoudylar, 97
Eight auricle, 183

ventricle, 183
Einia glottidis, 2UU
Eiug, abdominal, external, 381
internal, 381

femoral, 384
Eisorius, 145
Eivinus, ducts of, 265

notch of, 365
Eod-granules, 353
Eods of Corti, 378
Eolandic angle, 238

line, 238
Eolando, fissure of, 225

funiculus of, 235
Root of tooth, 260
Rosenmiiller, organ of, 339
Rostrum, 32
Rotatores spinae, 155
Round ligament of liver, 278
of uterus, 336

window, 367
Rugte of bladder, 320

Sac, lacrimal, 362
Saccule, .377
Sacculus laryngis, 299
Sacral arterv, lateral, 205
middle, 203

canal, 76

foramina, 75, 76

groove, 76

nerves, 256

plexus, 253
Sacro-coccygeal articulation, 125
Sacro-iliac articulation, 124
Sacro-sciatic ligament, 125

notch, greater, 85
Sacro-verti'bral articulation, 124
Sacrum, 74

ccMiters of ossification of, 77

muscular attachments of, 77
Sagittal sutur(% 25, .57
Salivary glands, 264
Sal|iiniio-|iliarvngeal fold, 268
Salpin^o-iiliaryngeus, 371
Santorini, emissary veins of, 214

Saphenous opening, 170, 384

veins, 218
Sarcolemma, 140
Sartorius, 170
Scala media, 377

tympani, 375

vestibuli, 375
Scalenus anticus, 149

mcdius, 149

posticus, 149
Scaphoid bone, 102

fossa, 34
Scapula, 91

angles of, 94

borders of, 94

development of, 94

ligaments of, 127

muscular attachments of, 95
Scarpa, foramen of, 47
Scarpa's triangle, 206
Schachowa, spiral tubule of, 313
Schindylesis, 118
Schlemm, canal of, 3.50

inferior ligament of, 127

internal ligament of, 127
Schneiderian membrane, 343
Schwann, white substance of, 222
Sciatic artery, 204

nerves, 2.54
Sclerotic, 347

arteries of, 347
Scrotum, .327
Sebaceous glands, .342
Second nerve, 241
Sella turcica, 32
Semicircular canals, .373

membranous, .376
Semilunar aortic valves, 185

bone, 102

fibrocartilages, 135

valves, 184
Semimembranosus, 175
Seminiferous tubules, 328
Semispinalis colli, 154

dorsi, 1.54
Semitendinosus, 174
Sense, organs of, 340
Septum crurale. .385

lucidum, 232

nasal, 67

j)ec(inif((rme, 325
scroti, ;)27

tul)iP, 39, 61,:«i8
Serratus magnus, 161

414

INDEX.

fcjcrratus posticus, inferior, 152

superior, 152
Sesamoid bones, 20
Seventh nerve, 240
Sharpey's perforating fibers, 19
Sheath, crural, 385
Shin, 110

Short bones, function of, 21
Shouhler-joiut, 127

muscles of, ItJl
Shrapnell's membrane, 365
Sigmoid cavities, 99

cavity, 100

flexure, 275

fossa, 30

notch, 54, 56
Sinus circularis iridis, 350

coronary, 220

definition of, 214

frontal, 25

mediastino-costalis, 308

mediastino-})hrenicus, 308

I)hrenico-costalis, 308

pocularis, 322, 331

of Valsalva, 184
Sinuses of dura mater, 214

frontal, 23
Sixth nerve, 346
Skin, 340
Skull, bones of, 22
Small intestine, 272
Smell, organs of, 343
Soft palate, 264
Solar plexus, 258
Soleus, 176
Solitary glands, 274
Sommering, yellow spot of, 351
Space of Tenon, 346
Spaces of Fontana, 350
Spermatic arterv, 203, 329

cord, 330
Spheno-ethmoidal recess, 67
Sphenoid bone, 31

articulations of, 34
body of, 31

centers of ossification of, 35
greater wings of, 32
lesser wings of, 34
Sphenoidal crest, 82

fissure, 33, 34, 60, 64

process, 51

sinuses, 31

turbinated bone, 32
Spheno-malar suture, 64

Spheno-maxillary fissure, 33, 64, 68

fossa, 69
Spheno-palatine foramen, 51, 67

ganglion, 244
Spheno-parietal suture, 57
Spheno-stai)liy linns, 371
Sphincter ani, external, 386
internal, 380
tertius, 386

pupilla?, 351

vagina% 388, 390

vesicae, 320
Spinal accessorv nerve, 247

cord, 239

columns of, 240
fissures of, 240
membranes of. 240
ventricle of, 241

foramen, 72

nerves, 248

veins, 217
Spinalis colli, 154

dorsi, 154
Spine of ischium, 86

of scapula, 91

of tibia, 110
Spinous process of bones, 21
of sphenoid, 33
of vertebra, 71
Spiral canal of cochlea, 374

groove, 95

line of femur, 108

tubercle of Schachowa, 313

valve, 282
Splanchnic nerves, 258
Spleen, 285
Spleen -pulp, 286
Splenic arterv, 202, 286

vein, 286
Splcnius capitis et colli, 152
Spongj' tissue of bone, 18

urethra, 322
S(|uamo-occipital portion. 27
S(|uamo-parietal suture, 57
S(|uamo-sphenoidal suture, 57
Squamous portion of temporal

bone, 35
Stapedius. 369
Stapes. 368

Stars of Verhayen, 315
Stellate ligament, 123

venous plexuses, 315
Stensen, foramen of, 47
Steusen's duct, 265

INDEX.

415

Stensen's duct, openings of, 264
Steruo-clavicular articulation, 126
Sterno-cleido-niastoid muscle, 146
Sterno-hyoid muscle, 14()
Sterno-thyroid muscle, 146
Sternum, SO

ligaments of, 124
Stilling, canal of, 354
Stirrup, 368
Stomach, 270

blood- and nerve-supply of, 272

coats of, 271

dimensions and position of, 271

relations of, 271
Straight tubules, 314
Stratum mucosum, 341
Striae longitudiuales, 232

medul lares, 234
Stylo-glossus, 148
Stylo-hyoid muscle, 147
Stvloid'process, 99, 100
of fibula, 112
of temporal, 39
Stylo-mastoid foramen, 39. 61
Stylo-pharyugeus muscle, 269
Subanconeus, 163
Subarachnoidean space, 223, 240
Subarcuate fossa, 3rf, 61
Subclavian artery, 195

surgical anatomy, 212

groove, 90

vein, 216
Subclavius, 161
Subcostal artery, 201
Subcostales, 159
Subcrural bursa, 134
Subcrureus, 172
Subdural space, 240
Subcpitluilial plexuses, 347
Sublingual fossa, 55

gland, 2(i5
Sublobular vein, 280
Submaxillary fossa, 56

ganglion, 245

gland, 265
8ul)s<;apular angle, 91

artery, 198

fossa, 91

nerves, 250
Subscapnlaris, 161
Sulci (»f ccrrbclium, 236
Sulcus spiralis, 377

tubfe, 31

tympanic us, 365

; Superciliary ridges, 23
! Sui)erior curved line, 28
Supinator brevis, 166

longus, 165
Supracondylar ridges, 97
Supraglenoid tubercle, 94
Supramarginal gyrus, 227
Supra-occipital bone, 27
Supra-orbital arch, 23
artery, 357
foramen, 65
notch, 23
Suprapubic ligament, 125
Suprarenal arterv, inferior, 203
middle, 202
capsules, 288
Suprascapular artery, 196
nerve, 250
notch, 94
Supraspinatus, 162
Supraspinous fossa, 91
Supreme curved line, 28
Suspensory ligament of incus, 369
of lens, 355
of liver, 277, 278
of malleus, 368
of penis, 325
of spleen, 285
Sustentaculum lienis, 285
Sutura dentata, 118
harmonia, 118
limbosa, 118
notha, 118
serrata, 118
squamosa, 118
vera, 117
Suture, basi-sphenoidal, 57
coronal, 57
ethmo-sphenoidal, 64
fronto-malar, 64
fronto-parietal, 57
fronto-si)hcnoidal, 64
interparietal, 57
lacrimo-ethmoidal, 64
lambdoid, 57
malo-maxillary, 64
masto-occipital, 57
masto-parit'tal, 57
occipito-parictal, 57
l»aIato-ma.\illary, 64
|)etro-occipital, 57
ptitro-sphenoiiJal, 57
sagittal, 57
of the skull, 57

416

INDEX.

Suture, spbciKi-niular, (j4

spheuo-purietal, 57

squauKJ-parietal, 57

squaiuo-sjiliL-uoidal, 57

transverse, 57
Sweat-glauds, 342
Sylviau line, '2'SU

point, 2'.i[)
Sylvius, fissure of, 225
Sympathetic nerve, 256
Symphysis of mandible, 55

of pubes, 87
Synarthroses, 117
Synchondrosis, 117
Syndesmosis, 117
Synostosis, 117

Tactile corpuscles, 341
Taenia hippocampi, 232
semieircularis, 230
Tapetum fibrosum, 349
Tarsal artery, 210
bones, 113
cartilages, 360
joints, 137
ligaments, 360
Tarso-metatarsal articulation, 139
Tarsus, svnovial sacs of, 139
Taste-buds, 343
Taste-hair, 343
Taste, organs of, 342
Tears, 361
Teeth, 260

blood- and nerve-supply of, 2G2
development of, 263
structure of, 261
varieties of, 261
Tegmen tympani, 38, 60, 366
Temiioral artery, superficial, 192
bone, 35

articulations of, 40
centersof ossification of, 40
mastoid portion, 3(5
muscular attaclnnents of,

40
petrous portion, 37
squamous portion, 35
fossa. 67
muscle, 145
ridges. 26, 68
inferior, 24
Temporary teeth, 260

a])]iearance of, 262
Temporo-malar canals, 49

Temporo - maxillary articulation,

122
Temporo-sphenoidal lobe, 226
Tendo oculi, 3(50
Tendon, conjoined, 156
Tendons, 141
Tenon, capsule of, 345

s])ace of, 346
Tensor fasciae femoris, 170

palati, 148

tarsi, 142

tympani, 369
Tenth nerve, 247
Tentorium cerebelli, 223
Teres major, 162

minor, 162
Testes, 327

descent of, 331

structure of, 328

vessels of, 329
Testicles, 327

nerves of, 330
Thalamencephalon, 224
Third nerve, 242

ventricle, 233
Thoracic aorta, 200

surgical anatomy, 212

artery, alar, 198
long, 198
superior, 197

duct, 221

nerves, 2.52
Thorax, measurements of, 310

muscles, 159

structure, form, and boundaries
of, 78

structures contained in, 80

veins of, 217
Thymus gland, 287

blood-suj)ply of, 288
Thyro-arytenoideus, 'SOB
Tliyro-epiuh)ttie ligament, 297
Thyro-epiglottideus, 300
Tliyro-glossal duct, 266
Tliyro-hyoid muscle, 146
Thyroid artery, superior, 191

axis, 196

cartilage, 195

foramen, 84

gland, 286

arteries of, 287
nerves of, 287

structure of, 288

veins of. 287

INDEX.

417

Thyroidea ima, 190
Tibia, 110

development of, 112

muscular attachments of, 112
Tibial artery, anterior, 209
posterior, 210

nerve, anterior, 255
posterior, 255
Tibialis anticus, 175

posticus, 177
Tibio-fibular articulation, 136
Tomes' fibers, 262
Tongue, 265

blood-supply of, 266

nerve-supply of, 266
Tonsil, 264

lingual, 266

pharyngeal, 268

tubal, 268
Tooth, parts of, 260
Torus transversus, 28
Trachea, 301

blood- and nerve-supply of, 303

relations of, in neck, 302
in thorax, 302
Trachealis muscle, 301
Trachelo-mastoid muscle, 154
Tractus spiralis foraminulentus, 380
Tragi cus, 364
Tragus, 363
Transversalis, 157

colli, 153, 196
Transverse colon, 275

disk, 140

fissure, 226

processes of vertebra, 71

suture, 57
Transversus auriculae, 364

perinei, 387
Trapezium, 104
Trapezius, 158
Trapezftid bone, 104

ligaTn<'nt, 127
Triangular ligament, 389

notch, 34
Triangularis sterni, 159
Tric('j)s (!xt(;nsor cubiti, 163
Triciisi.id valve, 1H2, 184
Trifacial nerve, 243
Trigeminus, 243
Trigonuni acustici, 234

habcmbr', 233

hypoglossi, 234

vagi, 234

27

j Trigonum vesicae, 320
Triticeo-glossus, 300
Trochanters, 21
I of femur, 108

; Trochlea of femur, 109
Trochlear fossa, 24
nerve, 242

surface of humerus, 97
Trochoides, 118
True pelvis, 88
ribs, 80
vertebrae, 69
Tubal tonsils, 268
Tube, Eustachian, 371
Tuber annulare, 235
of pons, 229
cinereura, 229
valvulae, 237
Tubercle, conoid, 90
of Darwin, 364
deltoid, 90
Lisfranc's, 82
of Lower, 183
supraglenoid, 94
Tubercles of bones, 21
Tuberosities of bones, 21
of humerus, 95
of tibia, 110
Tuberosity of ischium, 86
of radius, 100
of rib, 81
Tubular membrane, 222
Tubuli lactiferi, 339

uriniferi, 313
Tunica albuginea testis, 327
Ruyschiana, 349
vaginalis, 327
oculi, 345
l)ropria, 327
reflexa, 327
testis, 331
vasculosa, 327
Turbinated bones, 42
inferior, 52
crest, inferior, 46, 251
superior, 46
Tutamina oculi, 359
Twelfth nerve, 24H
Tympanic artery, 194, 370
n«'rve, 370
plexus, 370
sjiines, 365
Tympanum, 365, 366
ait(!ries of, 369

418

INDEX.

Tympanum, muscles of, 369

nerves of, 370
Tyson's glands, 326

Ulna, 97

development of. 99

muscular attachments of, 100
Ulnar artery, 199

nerve, 251
Umbilical fissure, 278

region, 291
Umbo, .365
Unciform bone, 104

process of ethmoid, 41
Uncinate gyrus, 226
Ungual processes, 106
Upper extremity, veins of, 215
Urachus, 319
Ureter, 317

muscles of, 320
Urethra, female, 323

male. 321

structure of, 323
Urinary organs, 312
Urogenital space. 332
Uterine arterv, 204, 336
Uterus. 3.34

blood-vessels of, 336

ligaments of, 3.35

masculinus, 322

nerves of, 337

structure of, 336
Utricle, 376
Uvea, 350
Uvula of cerebellum, 237

vesicfe, 321

Vagina, 333
Vaginal orifice, 332

process, 32

of temporal bone, 39
Vagus nerve, 247
Valsalva, sinus of, 184
Valve, aortic, 182

of Bauhin, 273, 275

coronary, 183

Eustachian, 183

of Hasner, 362

of Ileister, 282

ileo-cecal, 273, 275

mitral, 182, 185

pulmonary, 182

semilunar, 184

spiral, 282

Valve, tricuspid, 182, 184

of Vieussens, 2.33
Valves, pulmonary semilunar, 184

semilunar aortic, 185
Valvula? conniventes, 273
Vas abcrrans, 329

deferens, 329
Vasa etferentia, .328

nervorum. 222

vasorum, 187

vesta, 328
Vascular system, 181
Vastus externus. 171

internus, 172
Vein, axillary, 215

azygos, 217

emulgent, 316

iliac, common, 219
internal, 219

jugular, 215

portal, 279

renal, 316

saphenous, 218

splenic, 286

subclavian. 216

subglobular, 280

vertebral, 215
Veins, 213

of auricle, 364

of choroid. 349

dorsi-spinal, 217

of eye, 358

of head, 214
■ of heart, 220

hepatic, 280

interlobular, 280

of iris, 351

of kidney, 315

of larynx, .300

of lower extremity, 218

medulli-spinal, 218

meningo-rachidian, 218

of neck, 214

pulmonary, 220

spinal, 217

of testicle, 330

of thorax, 217

of upper extremity, 215
Vena cava, inferior, 219

superior, 216
Vena? basis vertebrarum, 218

comites, 214

innominatae, 216

interlobulares, 316

INDEX.

419

Venae proprife venales, 316

rectse, 316

vorticosre, 349
Ventrifde of cord, 241

fifth, 233

fourth, 234

of larvnx, 299

left. 185

risht, 183

third, 233
Ventricles of brain, 231

lateral, 231
Vermiform fossa, 30

processes, 236
Vertebra, articular processes of, 71

body of, 70

development of, 73

lamina; of, 71

pedicles of, 70

prominens, 73

spinous processes of, 71

transverse processes of, 71
Vertebrae, false, 69

true, 69
Vertebral artery, 196

articulations, 119

column, 69

line, .310

muscles, 149

notches, 70

vein, 215
Vertical plate of palate bone, 51
Verumontanum, 322
Vesical arteries, 204
Vesico-uterine lifjament, 335
Vesiculae seminales, .330
Vestibular nerve, 380
Vestibule of labyrinth, .372

of vagina, 3.32

Vidian canal, 34

nerve, 345
Viscera, abdominal, 289
Viscus, definition, 259
Vitelline membrane, 338
Vitellus, .3.38
Vitreous body, 354

humor, .346
Vocal cords, 298
Vomer, .53
Vulva, 331

Wharton's duct, 265

openings of, 264
White substance of Schwann, 222
Willis, circle of, 194
Wings of sphenoid, greater, 32
lesser, 34

of vomer, 53
Winslow, foramen of. 293
Wisdom teeth, 261
Worm, 236
Wormian bones, 20
Wrisberg, cartilages of, 297

ligament of, 135
Wrist-joint, 130

Y-LIGAMEXT, 1.32

Yellow maiTow, 19

spot of Sommering, 351

ZiXN, zonula of, .355
Zona arcuata, 378

pellucida. 338

radiata. 338
Zonula of Zinn, .355
Zygomatic fossa, 68

process, .35, 49
Zygomaticus minor, 144

Catalogue the Medical Publications

OF

W. B. SAUNDERS & COMPANY

PHILADELPHIA .j8 jt .jt .ji .Jt LONDON

925 Walnut Street ji .Jt .ji .Jt .jt 161 Strand, VV. C.

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sent in any other way is at the risk of the sender.

SPECIAL To physicians of approved credit books will be sent, post-paid, on the following
OFFER terms : $5.00 cash upon delivery of books, and monthly payments of 555.00 there-
after until full amount is paid. Any one or two volumes will be sent on thirty days' time

to those who do not care to make a larger purchase.

AN AMERICAN TEXT=BOOK OF APPLIED THERAPEUTICS.

Edited by James C. Wilson, M. D., Professor of Practice of Medi.ir.e ar.d
of Clinical Medicine, Jefferson Medical College, Philadelphia. Handsome
imperial octavo volume of 1326 pages. Illustrated. Cloth, $7.00 net ;
Sheep or Half Morocco, $8.00 net. Sold by Subscription.

AN AMERICAN TE.\T=BOOK OF THE DISEASES OF CHIL=
DREN. Second Edition, Revised.

Edited by Louis Starr. M. D., Consulting Pediatrist to the Maternity Hos-
pital, etc'; assisted by THOMPSON S. Westcott. M. D., .Attending Physi-
cian to the Dispensary for Diseases of Children, Hospital of the University
of Pennsylvania. Handsome imperial octavo volume of 1244 pages, pro-
fusely illustrated. Cloth, $7.00 net ; Sheep or Half Morocco, $8.00 net.
Sold by Subscription.

AN AMERICAN TEXT=BOOK OF DISEASES OF THE EYE,
EAR, NOSE, AND THROAT.

Edited bv G. E. DE SCHWEIMTZ, M. D. Professor of Ophthalmology.
Jefferson 'Medical College, Philadelphia; and B. .ALE.VANDER Randall.
M. D.. Clinical Professor of Diseases of the Elir, University of Pennsylvania.
Imperial octavo, 1251 pages; 706 illustrations, 59 of them in colors. Cloth,
^7,00 net ; Sheep or Ha.f .Morocco, $3.oo net. Sold by Subscription.

MEDICAL PUBLICATIONS

AN AMERICAN TEXT=BOOK OF QENITO=URINARY AND

SKIN DISEASES.

Edited by L. Boi.'lON Bangs, M. D., Professor of Gcnito-Urinury ?urgery,
University and Bellevue Hospital Medical College, New York ; and W. A.
Hardaway, M. D., Professor of Diseases of the Skin, Missouri Medical
College. Imperial octavo volume of 1229 pages, with 300 engravings and
20 full-page colored plates. Cloth, $7.00 net ; Sheep or Half Morocco,
^8.00 net. Sold by Subscription.

AN AMERICAN TEXT=BOOK OF GYNECOLOGY, MEDICAL
AND SURGICAL. Second Edition, Revised.

Edited by j. M. Baldv, M. D., Professor of Gynecology, Philadelphia
Polyclinic, etc. Handsome imperial octavo volume of 718 pages; 341 illus-
trations in the text, and 38 colored and half-tone plates. Cloth, ^6.00 net ;
Sheep or Half Morocco, $7.00 net. Sold by Subscription.

AN AMERICAN TEXT=BOOK OF LEGAL MEDICINE AND

TOXICOLOGY.

Edited by Frederick Peterson, M. D., Chief of Clinic, Nervous Depart-
ment, College of Physicians and Surgeons, New York ; and Walter S.
Haines, M. D., Professor of Chemistry, Pharmacy, and Toxicology, Rush
Medical College, Chicago. In Preparation.

AN AMERICAN TEXT=BOOK OF OBSTETRICS.

Edited by RICHARD C. NoRRis, M. D ; Art Editor, Robert L. Dickinson,
M. D. Handsome imperial octavo volume of 1014 pages ; nearly 900 beau-
tiful colored and half-tone illustrations. Cloth, ^7.00 net ; Sheep or Half
Morocco, $8.00 net. Sold by Subscription.

AN AMERICAN TEXT=BOOK OF PATHOLOGY.

Edited by LUDWIG Hektoen, M. D., Professor of Pathology in Rush
Medical College, Chicago ; and David Riesman, M. D., Demonstrator of
Pathologic Histology in the University of Pennsylvania. Handsome im-
perial octavo, over 1200 pages, profusely illustrated. By Subscription.

AN AMERICAN TEXT=BOOK OF PHYSIOLOGY. Second Edi=
tion. Revised, in Two Volumes.

Edited by WILLIAM H. HoWELL, Ph. D., M. D., Professor of Physiology,
Johns Hopkins University, Baltimore, Md. Two royal octavo volumes of
about 600 pages each. Fully illustrated. Per volume: Cloth, ^3.00 net;
Sheep or Haff Morocco, $3.75 net.

AN AMERICAN TEXT=BOOK OF SURGERY. Third Edition.

Edited by William W. Keen. M. D., LL.D., F. R. C. S. (Hon.); and
y. William White, M. D., Ph. D. Handsome octavo volume of 1250
pages ; 496 wood-cuts and 37 colored and half-tone plates. Thoroughly
revised and enlarged, with a section devoted to "The Use of the Ront-
gen Ravs in Surgery." Cloth, $7.00 net; Sheep or Half Morocco,
fi8.oo net.

OF W. B. SAUNDERS 6- CO.

THE NEW STANDARD THE NEW STANDARD

THE AMERICAN ILLUSTRATED MEDICAL DICTIONARY.
Second Edition, Revised.

For Practitioners and Students. A Complete Dictionary of the Terms used
in Medicine, Surgery, Dentistry, Pharmacy, Chemistry, and the kindred
branches, including much collateral information of an encyclopedic character,
together with new and elaborate tables of Arteries, Muscles, Nerves, Veins,
etc. ; of Bacilli, Bacteria, Micrococci, Streptococci ; Eponymic Tables of
Diseases, Operations, Signs and Symptoms, Stains, Tests, Methods of Treat-
ment, etc., etc. By W. A. Newman Dorland, A. M., M. D., Editor
of the " American Pocket Medical Dictionary." Handsome large octavo,
nearly 8oo pages, bound in full flexible leather. Price, ^4.50 net; with
thumb index, $5.00 net.

Gives a Maximum Amount of Matter in a Minimum Space and at the Lowest

Possible Cost.

This Revised Edition contains all the Latest Terms.

" I must acknowledge my astonishment at seeing how much he has condensed within
relatively small space. I find nothing to criticise, very much to commend, and was in-
terested in finding some of the new words which are not in other recent dictionaries." —
RoswELL Park, Professor of Principles and Practice of Surgery and Clinical Surgery,
University of Buffalo.

" I congratulate you upon giving to the profession a dictionary so compact in its structure,
and so replete with information required by the busy practitioner and student. It is a
necessity as well as an informed companion to every doctor. It should be upon the desk
of every practitioner and student of medicine." — John B. Murphy, Professor of Surgery
and Clinical Surgery, Northwestern University Medical School, Chicago.

THE AMERICAN POCKET MEDICAL DICTIONARY. Third
Edition, Revised.

Edited by W. A. NEWMAN DoRLAND., M. D., Assistant Obstetrician to the
Hospital of the University of Pennsylvania; Fellow of the American Acad-
emy (jf Medicine. Containing the pronunciation and definition of the prin-
cipal words used in medicine and kindred sciences, with 64 extensive tables.
Handsomely bound in flexible leather, with gold edges. Price $1.00 net;
with thumb index, $1.25 net.

THE AMERICAN YEAR=BOOK OF MEDICINE AND SURGERY.

A Yearly Digest of Scientific Progress and Authoritative Opinion in all
branches of Medicine and Surgery, drawn from journals, monographs, and
text-books of the leading American and Foreign authors and investigators.
Arranged with editorial comments, by eminent American specialists, under
the editorial charge of George M. Gould, M. D. Year-Book of 1901
in two volumes — Vol. I. including Cieneral Medicine ; Vol. IL, General Sur-
gery. Per volume : Cloth, $3.00 net ; Half Morocco, $3.75 net. Sold by Sub-
scription.

ABBOTT ON TRANSMISSIBLE DISEASES. Second Edition,
Revised.

The Hygiene (jf Transmissible Diseases: their Causation, Modesof Dissem-
ination, and .VIetiiods of IVevention. By A. C. AhhoTI', M. D., I'rofcssor
of Hygiene and Fiacteriology, University of Pennsylvania. Octavo, 351
pages, with numt^rous illustrations. Cloth, ^2.50 net.

MEDICAL rURLlCA TlUNS

ANDERS' PRACTICE OF MEDICINE. Fifth Revised Edition.

A Text-Book of the Practice of Medicine. By J AMES M. ANDERS, M. D..
Ph. D., LL. D.. Professor of the Practice of Medicine and of Clinical Med-
icine, Medico-Chirurgical College, Philadelpliia. Handsome octavo volume
of 1292 pages, fully illustrated. Cloth, $5.50 net; Sheep or Half Morocco,
$6.50 net.

BASTIN'S BOTANY.

Laboratory Exercises in Botany. By Edson S. Bastin, M. A., late Pro-
fessor of Materia Medica and Botany, Philadelphia College of Pharmacy.
Octavo, 536 pages, with 87 plates. Cloth, ^2.00 net.

BECK ON FRACTURES.

Fractures. By CARL BECK, M. D., Surgeon to St. Mark's Hospital and
the New York German Poliklinik, etc. With an appendix on the Practical
Use of the Rontgen Rays. 335 pages, 170 illustrations. Cloth, $3.50 net.

BECK'S SURGICAL ASEPSIS.

A Manual of Surgical Asepsis. By Carl Beck, M. D., Surgeon to St.
Mark's Hospital and the New York German Poliklinik, etc. 306 pages; 65
text-illustrations and 12 full-page plates. Cloth, $1.25 net.

BOISLINIERE'S OBSTETRIC ACCIDENTS, EMERGENCIES,

AND OPERATIONS.

Obstetric Accidents, Emergencies, and Operations. By L. Ch. BOISLIN-
IERE, M.D., late Emeritus Professor of Obstetrics, St. Louis Medical Col-
lege. 381 pages, handsomely illustrated. Cloth, ^2.00 net.

BOHM, DAVIDOFF, AND HUBER'S HISTOLOGY.

A Text-Book of Human Histology. Including Microscopic Technic. By
Dr. a. a. Bohm and Dr. M. von Davidoff, of Munich, and G. Carl
Huber, M. D., Junior Professor of Anatomy and Director of Histological
Laboratory, University of Michigan. Handsome octavo of 501 pages, with
351 beautiful original illustrations. Cloth, $3.50 net.

BUTLER'S MATERIA MEDICA, THERAPEUTICS, AND
PHARMACOLOGY. Third Edition, Revised.

A Text-Book of Materia Medica, Therapeutics, and Pharmacology. By
George F. Butler, Ph.G., M. D., Professor of Materia Medica and of
Chnical Medicine, College of Physicians and Surgeons, Chicago. Octavo,
874 pages, illustrated. Cloth, $4.00 net ; Sheep or Half Morocco, fc.oo net.

CERNA ON THE NEWER REMEDIES. Second Edition,
Revised.

Notes on the Newer Remedies, their Therapeutic Applications and Modes
of Administration. By David Cerna, M. D., Ph. D., Demonstrator of
Physiology, Medical Department, University of Texas. Rewritten and
greatly enlarged. Post-octavo, 253 pages. Cloth, $1.00 net.

OF W. B. SAUNDERS &- CO.

CHAPIN ON INSANITY.

A Compendium of Insanity. By JOHN B. Chapin, M. D., LL.D., Phy-
sician-in-Chief, Pennsylvania Hospital for the Insane; Honorary Member
of the Medico-Psychological Society of Great Britain, of the Society of
Mental Medicine of Belgium, etc. i2mo, 234 pages, illustrated. Cloth,
^1.25 net.

CHAPMAN'S MEDICAL JURISPRUDENCE AND TOXICOLOGY.
Second Edition, Revised.

Medical Jurisprudence and Toxicology. By Henry C. Chapman, M. D.,
Professor of Institutes of Medicine and Medical Jurisprudence, Jefferson
Medical College of Philadelphia. 254 pages, with 55 illustrations and 3
full-page plates in colors. Cloth, $1,50 net.

CHURCH AND PETERSON'S NERVOUS AND MENTAL D1S=
EASES. Third Edition, Revised and Enlarged.

Nervous and Mental Diseases. By ARCHIBALD CHURCH, M. D., Pro-
fessor of Nervous and Mental Diseases, and Head of the Neurological
Department, Northwestern University Medical School, Chicago ; and
Frederick Peterson, M. D., Chief of Clinic, Nervous Department, Col-
lege of Physicians and Surgeons, New York. Handsome octavo volume of
875 pages, profusely illustrated. Cloth, $5.00 net ; Sheep or Half Morocco.
^6.00 net.

CLARKSON'S HISTOLOGY.

A Text-Book of Histology, Descriptive and Practical. By Arthur Clark-
SON, M. B., C. M. Edin., formerly Demonstrator of Physiology in the Owen's
College, Manchester ; late Demonstrator of Physiology in Yorkshire College,
Leeds. Large octavo, 554 pages ; 22 engravings and 174 beautifully colored
original illustrations. Cloth, ^4.00 net.

CORWIN'S PHYSICAL DIAGNOSIS. Third Edition, Revised.

Essentials of Physical Diagnosis of the Thorax. By ARTHUR M. CORWIN,
A. M., M. D., Instructor in Physical Diagnosis in Rush Medical College,
Chicago. 219 pages, illustrated. Cloth, ^1.25 net.

CROOKSHANK'S BACTERIOLOGY. Fourth Edition, Revised.

A Text-Book of Bacteriology. By Edgar M. Crookshank, M. B., Pro-
fessor of Comparative Pathology and Bacteriology, King's College, London.
Octavo, 700 pages, 273 engravings and 22 original colored plates. Cloth,
$6.50 net ; Half Morocco, $7.50 net.

DACOSTA'S SURGERY. Third Edition, Revised.

Modern Surgery, Cencral and 0|icrativc. By JoHN CHALMERS DaCoSTA,
M. D., Professor of l^rincipk-s of Surgery and Clinical Surgery, Jefferson
Medical College, Philadelphia ; Surgeon to the Philadelphia Hospital, etc.
Handsome octavo volume of 11 17 pages, profusely illustrated. Cloth, ^5.00
net; Sheep or Half Morocco, ^'^•oo net.

Enlarged by over 200 Pages, with more than 100 New Illus-
trations.

MEDIC A L PUBL ICA TIOXS

DAVIS'S OBSTETRIC NURSING.

Obstetric and Gynecologic Nursing. By Edward P. Davis, A. M., M. D.,
Professor of Obstetrics in Jefferson Medical College and the Philadelphia
Polyclinic ; Obstetrician and Gynecologist to the Philadelphia Hospital.
i2mo volume of 400 pages, fully illustrated. Crushed buckram, $1.75 net.

DE SCHWEINITZ ON DISEASES OF THE EYE. Third Edi-
tion, Revised.

Diseases of the Eye. A Handbook of Ophthalmic Practice. By G. E.
DE SCHWEINITZ, M. D., Professor of Ophthalmology, Jefferson Medical
College, Philadelpliia, etc. Handsome royal octavo volume of 696 pages ;
256 fine illustrations and 2 chromo-lithographic plates. Cloth, $4.00 net ;
Sheep or Half Morocco, $5.00 net.

DORLAND'S DICTIONARIES.

[See American Illustrated Medical Dictionary and American
Pocket Atedical Dictionary on page 3.]

DORLAND'S OBSTETRICS. Second Edition, Revised and
Greatly Enlarged.

Modern Obstetrics. By W. A. NEWMAN DORL.A.ND, M. D., Assistant
Demonstrator of Obstetrics, University of Pennsylvania ; Associate in Gyne-
cology, Philadelphia Polyclinic. Octavo volume of 797 pages, with 201
illustrations. Cloth, 54.00 net.

EICHHORST'S PRACTICE OF MEDICINE.

A Text-Book of the Practice of Medicine. By Dr. Herman Eichhorst,
Professor of Special Pathology and Therapeutics and Director of the Medi-
cal Clinic, University of Zurich. Translated and edited by AUGUSTUS A.
ESHNER, M. D., Professor of Clinical Medicine, Philadelphia Polyclinic.
Two royal octavo volumes, 600 pages each, 150 illustrations. Per set :
Cloth, S6.00 net; Sheep or Half Morocco, $7.50 net.

FRIEDRICH AND CURTIS ON THE NOSE, THROAT, AND
EAR.

Rhinolog)', Laryngology, and Otolog\\ and their Significance in General
Medicine. By Dr. E. P. Friedrich, of Leipzig. Edited by H. HoLBROOK
Curtis, M. D., Consulting Surgeon to the New York Nose and Throat Hos-
pital. Octavo, 348 pages. Cloth, $2.50 net.

FROTHINGHAM'S GUIDE FOR THE BACTERIOLOGIST.

Laboraton,' Guide for the Bacteriologist. By Langdon Frothingham,
M. D. v.. Assistant in Bacteriology and Veterinary Science, Sheffield Scien-
tific School, Yale University. Illustrated. Cloth, 75 cts. net.

GARRIGUES' DISEASES OF WOMEN. Third Edition, Re=

vised.

Diseases of Women. By Henry J. Garrigues, A. M., M. D., Gynecolo-
gist to St. Mark's Hospital and to the German Dispensary, New York City.
Octavo, 756 pages, with 367 engravings and colored plates. Cloth, ^4.50
net; Sheep or Half Morocco, $5.50 net.

OF IV. B. SAUNDERS <^ CO.

GOULD AND PYLE'S CURIOSITIES OF MEDICINE.

Anomalies and Curios ties of Medicine. By Geokge M. GoL'LD, M. D.,
and Walter L. Pyle, M. D. An encyclopedic collection of rare and ex-
traordinary cases and of the most striking instances of abnormality in all
branches of Medicine and Surgery, derived from an exhaustive research of
medical literature from its origin to the present day, abstracted, classified,
annotated, and indexed. Handsome octavo volume of 968 pages ; 295 en-
gravings and 12 full-page plates. Popular Edition. Cloth, $3.00 net ; Sheep
or Half Morocco, S4.00 net.

GRAFSTROM'S MECHANO=THERAPY.

A Text-Book of Mechano-Therapy (Massage and Medical Gymnastics).
By Axel V. Grafstrom, B. Sc, M. D., late House Physician. City Hos-
pital, Blackweli's Island, New York. i2mo, 139 pages, illustrated. Cloth,
^i.oo net.

GRIFFITH ON THE BABY. Second Edition, Revised.

The Care of the Baby. By J. P. Crozer GRIFFITH, M. D., Clinical Pro-
fessor of Diseases of Children, University of Pennsylvania ; Physician to the
Children's Hospital, Philadelphia, etc. i2mo, 404 pages, 67 illustrations
and 5 plates. Cloth, $1.50 net.

GRIFFITH'S WEIGHT CHART.

Infant's Weight Chart. Designed by J. P. Crozer Griffith, M. D.,
Clinical Professor of Diseases of Children, University of Pennsylvania. 25
charts in each pad. Per pad, 50 cts. net.

HART'S DIET IN SICKNESS AND IN HEALTH.

Diet in Sickness and Health. By Mrs. Ernest Hart, formerly Student
of the Faculty of Medicine of Paris and of the London School of Medicine
for Women ; with an Introduction by Sir Henry Thompson, F. R. C. S.,
M. D., London. 220 pages. Cloth, $1.50 net.

HAYNES' ANATOMY.

A Manual of Anatomy. By IRVING S. Haynes, M. D., Professor of Prac-
tical Anatomy in Cornell University Medical College. 680 pages ; 42 dia-
grams and 134 full-page half-tone illustrations from original photographs of
the author's dissections. Cloth, $2.50 net.

HEISLER'S EMBRYOLOGY. Second Edition, Revised.

A Text-Book of Embryology. By John C. Heisler. M. D., Professor of
Anatomy, Mcdico-Chirurgical College, Philadelphia. Octavo volume of 405
pages, handsomely illustrated. Cloth, $2.50 net.

HIRST'S OBSTETRICS. Third Edition, Revised and Enlarged.

A Text-Book of Obstetrics. By liAkfoN CooKE Hirst, M.D., iVofessor
of 01)stetrics, University of Pennsylvani i. H.indsome octavo volume of
873 pigf-'S, 704 illustrations, 36 of them in colors. Cloth, $5.00 net ; Sheep
or Half Morocco, $6.00 net.

MEDIC A L PUBLIC A TIONS

HYDE & MONTGOMERY ON SYPHILIS AND THE VENEREAL
DISEASES. 2d Edition, Revised and Greatly Enlarged.

Syphilis and the Venerea! Diseases. By James Nevins Hyde, M. D., Pro-
fessor of Skin and Venereal Diseases, and Frank H. Montgomery, M. D.,
Associate Professor of Skin, Genito-Urinary, and Venereal Diseases in Rush
Medical College, Chicago, 111. Octavo, 594 pages, profusely illustrated.
Cloth, ^4.00 net.

THE INTERNATIONAL TEXT=BOOK OF SURGERY. In Two
Volumes,

Bv American and British Authors. Edited bv J. COLLINS Warren, M. D.,
LL. D., F. R.C. S. (Hon.), Professor of Surgery, Harvard Medical School,
Boston ; and A. Pearce Gould, M. S., F. R. C. S., Lecturer on Practical
Surgery and Teacher of Operative Surgery, Middlesex Hospital Medical
School, London, Eng. Vol. L General Surgery. — Handsome octavo, 947
pages, with 458 beautiful illustrations and 9 lithographic plates. Vol. IL
Special or Regioial Surgery. — Handsome octavo, 1072 pages, with 471
beautiful illustrations and 8 hthographic plates. Sold by Subscription.
Prices per volume : Cloth, 35.00 net: Sheep or Half Morocco, $6.00 net.

" It is the most valuable work on the subject that has appeared in some years. The
clinician and the pathologist have joined hands in its production, and the result must be a
satisfaction to the editors as it is a gratification to the conscientious reader." — Annals 0/
Surgery.

" This is a work which comes to us on its own intrinsic merits. Of the latter it has
very many. The arrangement of subjects is e.xcellent, and their treatment by the different
authors is equally so. What is especially to be recommended is the painstaking endeavor
of each writer to make his subject clear and to the point. To this end particularly is the
technique of operations lucidly described in all necessary detail. And withal the work is up
to dite in a very remarkable degree, many of the latest operations in the different regional
parts of the body being given in full details. There is not a chapter in the work from which
the reader mav not learn something new." — Medical Record, New York.

JACKSON'S DISEASES OF THE EYE.

A Manual of Diseases of the Eye. By Edward Jack.son, A.M., M. D..
Emeritus Professor of Diseases of the Eye, Philadelphia Polyclinic and Col-
lege for Graduates in Medicine. i2mo, volume of 535 pages, with 178 illus-
trations, mostly from drawings by the author. Cloth, $2.50 net.

KEATINQ'S LIFE INSURANCE.

How to Examine for LTe Insurance. By John M. Keating, M. D., Fellow
of the College of Physicians of Philadelphia; Ex-President of the Association
of Life Insurance Medical Directors. Royal octavo, 211 pages. With
numerous illustrations. Cloth, $2.00 net.

KEEN ON THE SURGERY OF TYPHOID FEVER.

The Surgical Complications and Sequels of Tvphoid Fever. By Wm. W.
Keen, M. D., LL.D.. F, R. C. S. (Hon.), Professor of the Principles of Sur-
gery and of Clinical Surgery, Jefferson Medical College, Philadelphia, etc.
Octavo volume of 386 pages, illustrated. Cloth, $3.00 net.

KEEN'S OPERATION BLANK. Second Edition, Revised Form.

An Operation Blank, with Lists of Instruments, etc. Required in Various
Operations. Prepared by W. W. Keen, M. D., LL.D., F. R. C.S. (Hon.),
Professor of the Principles of Surgery and of Clinical Surgery, Jefferson
Medical College, Philadelphia. Price per pad, of 50 blanks, 50 cts. net.

OF W. B. SAUNDERS d- CO.

KYLE ON THE NOSE AND THROAT. Second Edition.

Diseases of tlie Nose and Throat. By D. Braden Kvle, M. D., Clinical
Professor of Laryngology and Rhinology, Jefferson Medical College, Phila-
delphia. Octavo, 646 pages ; over 150 illustrations and 6 lithographic plates.
Cloth, $4.00 net; Sheep or Half Morocco, $5.00 net.

LAINE'S TEMPERATURE CHART.

Temperature Chart. Prepared by D. T. Laine, M. D. Size 8 x 131^
inches. A conveniently arranged Chart for recording Temperature, with
columns for daily amounts of Urinary and Fecal Excretions, Food, Re-
marks, etc. On the back of each chart is given the Brand treatment of
Typhoid Fever. Price, per pad of 25 charts, 50 cts. net.

LEVY, KLEMPERER, AND ESHNER'S CLINICAL BACTERI=
OLOQY.

The Elements of CUnical Bacteriolog\^ By Dr. Ernst Lew, Professor
in the University of Strasburg, and Dr. Felix Klemperer, Privatdocent
in the University of Strasburg. Translated and edited by AUGUSTUS A.
Eshner, M. D., Professor of Clinical Medicine, Philadelphia Polyclinic.
Octavo, 440 pages, fully illustrated. Cloth, $2.50 net.

LOCKWOOD'S PRACTICE OF MEDICINE. Second Edition,
Revised and Enlarged.

A Manual of the Practice of Medicine. By GEORGE ROE LoCKWOuD,
M. D., Professor of Practice in the Women's Medical College. of the New
York Infirmary, etc.

LONG'S SYLLABUS OF GYNECOLOGY.

A Syllabus of Gynecology, arranged in Conformity with "An American
Text-Book of Gynecology." By J. W. LONG, M. D., Professor of Dis-
eases of Women and Children, Medical College of Virginia, etc. Cloth,
interleaved. Si. 00 net.

MACDONALD'S SURGICAL DIAGNOSIS AND TREATMENT.

Surgical Diagnosis and Treatment. By J. W. Macdoxald, M. D. Edin.,
F. R.C. S. Edin., Professor of Practice of Surgery and Clinical Surgery,
Hamline University. Handsome octavo, 800 pages, fully illustrated. Cloth,
$5.00 net; Sheep or Half Morocco, $6.00 net.

MALLORY AND WRIGHT'S PATHOLOGICAL TECHNIQUE.
Second Edition, Revised and Enlarged.

Pathological Technique. A Practical Manual for T^aboratory Work in
Pathology, Bacteriology, and Morbid .Anatomy, with chapters on Post-
Mortem Technique and the Performance of Autopsies. By FRANK B.
MaLI.ory, a. M., M. D., Assistant Professor of Pathology, Harvard Uni-
versity .Medical School, l^>oston ; and jAMKs H. Wrigiit. A. M., M.D.,
Instructor in Pathologv, Harvard University Medical School, Boston.

McFARLAND'S PATHOGENIC BACTERIA. Third Edition,
increased in size by over 100 Pages.

Text-Book upon the Pathogenic Bacteria. By JosKI'H .McFarland,
M. D., Professor of Patiiology and Fiacteriology, Mcdico-Chirnrgical Col-
Irge of Philadelphia, etc. Octavo volume (jf 621 pages, finely illustrated.
Cloth, $3.25 net.

lo MEDICAL PUBLICATIONS

MEIGS ON FEEDING IN INFANCY.

Feeding in Early Infancy. By ARTHUR V. Meigs, M. D. Bound in limp
cloth, flush edges, 25 cts. net.

MOORE'S ORTHOPEDIC SURGERY.

A Manual of Orthopedic Surgery. By James E. Moore, M. D., Professor
of Orthopedics and Adjunct Professor of CHnical Surgery, University of
Minnesota, College of Medicine and surgery. Octavo volume of 356 pages,
handsomely illustrated. Cloth, ^2.50 net.

MORTEN'S NURSES' DICTIONARY.

Nurses' Dictionary of Medical Terms and Nursing Treatment. Containing
Definitions of the Principal Medical and Nursing Terms and Abbreviations;
of the Instruments, Drugs, Diseases, Accidents, Treatments, Operations,
Foods, Appliances, etc. encountered in the ward or in the sick-room. By
HONNOR Morten, author of" How to Become a Nurse," etc. i6mo, 140
pages. Cloth, ^i.oo net.

NANCREDE'S ANATOMY AND DISSECTION. Fourth Edition.

Essentials of Anatomy and Manual of Practical Dissection. By CHARLES
B. Nancrede, M. D.', LL.D., Professor of Surgery and of Clinical Surgery,
University of Michigan, Ann Arbor. Post-octavo, 500 pages, with full-page
lithographic plates in colors and nearly 200 illustrations. Extra Cloth (or
Oilcloth for dissection-room), |l2.oo net.

NANCREDE'S PRINCIPLES OF SURGERY.

Lectures on the Principles of Surgery. By CHARLES B. NANCREDE, M. D.,
LL.D,, Professor of Surgery and of Clinical Surgery, University of Michigan,
Ann Arbor. Octavo, 398 pages, illustrated. Cloth, ^2.50 net.

NORRIS'S SYLLABUS OF OBSTETRICS. Third Edition,
Revised.

Syllabus of Obstetrical Lectures in the Medical Department of the University
of Pennsylvania. By Richard C. Norris, A.M., M. D., Instructor in
Obstetrics and Lecturer on Clinical and Operative Obstetrics, University
of Pennsylvania. Crown octavo, 222 pages. Cloth, interleaved for notes,
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OGDEN ON THE URINE.

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NOTHNAGEL^S ENCYCLOPEDIA

VOLUMES JUST ISSUED AND IN PRESS

VOLUME I

Editor, William Osier, M. D.,

F.R.CR

Professor of Medicine in Johns Hopkins
University

CONTENTS

Typhoid Fever. By Dr. H. Cukschmann,
ul" Leipsic, Typhus Fever. By Dr. H.
Cukschmann, of Leipsic.

Handsome octavo volume of about 600 pages.
Just Issued

VOLUME n

Editor, Sir J, W. Moore, B. A., M. D.,

F.R.CP.L, of Dublin

Professor of Practice of Medicine, Royal
College of Surgeons in Ireland

CONTENTS

Erysipelas and Erysipeloid. By Dr. H.
Lenhartz, of Hamburg. Cholera Asi-
atica and Cholera Nostras By Dr
K. V(jn Liecermeistek, of lijbingen
Whooping Cough and Hay Fever. By
Dk. (t. Sticker, of Giessen. Varicella
By Dr. Th. vo.n Jurgense.n, of Tiibingen
Variola (including Vaccination). B\
Dr. H. Immekmann, of Basle.

Handsome octavo volume of over 700 pages.
Just Issued

VOLUME vn

Editor, John H. Musser, M. D.

Professor of Clinical Medicine , L'>iiversity
of Pennsylz'u)iia

CONTENTS

Diseases of the Bronchi. By Dr. F. A.
Hoffmann, of Leipsic. Diseases of the
Fleura. By Dk. Rosenbach, of Berlin.
Pneumonia. By Dk. E. Alfrecht, of
Magdeburg.

VOLUME VIU
Editor, Charles G. Stockton, M. D.

Professor of Medicine, University of Buffalo

CONTENTS

Diseases of the Stomach. By Du. F.
RiEGEL, of Giessen.

VOLUME EX
Editor, Frederick A. Packard, M. D.

Physician to the Pennsylvania Hospital and
to the Children's Hospital, Philadelphia

CONTENTS
Diseases of the Liver. By Drs. H.

fjLINCKE and Cj. HrippE-SEVLER, of Kiel.

VOLUME m
Editor, William P. Northrup, M. D.

Professor of Pediatrics, University and
Bellevue Medical College

CONTENTS
Measles. By I)k. In. von Jurcensen, of
Tiibingen. Scarlet Fever. By the same
author. Rotheln. I'.y the same author.

VOLUME VI
Editor, Alfred Stengel, M. D.

J'rofessor of Clinical Medic i>ie. University
of Pennsyh'ania

CONTENTS

Anemia. I'>y Dk. I'. Kiiki.k ir, of Frank-
lort-on-the-.\Iain, and I)k. A. Lazaris, of
Cjharloitenburg. Chlorosis. By \)\<. K.
V'>N Nf)ORi)F.N, of Fr.-inklorl-on the-.\Iain.
Diseases of the Spleen and Hemor-
rhagic Diathesis. By Dk. AL Litien,
ot Berlin.

VOLUME X
Editor, Reginald H. Fitz, A, M., M.D.

Hct sey Professor of the Theory and Prac-
tice of Physic, Harvard University

CONTENTS

Diseas s of the Pancreas. By Dr. L.
(JsER, of Vienna. Diseases of the Supra-
renals. By Dk. K. Nfissei, of \ ienna.

VOLUMES IV, V, and XI

Editors announced later

Vol. IV. — Influenza and Dengue. By Dr.
<). Lekhtenstein, of Cologne. Malarial
Diseases. By Dr. J. Mannaiserc;, of

\ iciina.

Vol. v.— Tuberculosis and Acute General
Miliary Tuberculosis. By Dk. (1. Cor-
Ni:r, (jf I'erlin.

Vol. X I. -Diseases of th- Intestines and
Peritoneum. By Dk. H. Nothnauel,
of N'ienna.

19

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ANATOMY, EMBRYOLOGY, HIS-
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Bohm, Davidoff, and Huber — A Text-
Book of Histology, 4

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Haynes — A Manual of Anatomy, ... 7

Heisler — A Text-Book of Embryology, . 7

Leroy — Essentials of Histology, .... 15

Nancrede — Essentials of Anatomy, . . . 15
Nancrede — Essentials of Anatomy and

Manual of Practical Dissection, .... 10

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Frothingham — Laboratory Guide, . . . 6

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Levy and Klemperer's Clinical Bacte-
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Technique, 9

McFarland — Pathogenic Bacteria, ... 9

CHARTS, DIET-LISTS, ETC.

Griffith — InfaHt's Weight Chart, .... 7

Hart — Diet in Sickness and in Health, . 7

Keen — Operation Blank, 8

Laine — Temperature Chart, 9

Meigs — Feeding in Early Infancy, ... 10

Starr — Diets for Infants and Children, . 12

Thomas — Diet-Lists, 13

CHEMISTRY AND PHYSICS.
Brock way — Essentials of Medical

Physics, 15

Wolff — Essentials of Medical Chemistry, 15

CHILDREN.
An American Text-Book of Diseases

of Children, i

Griffith — Care of the Baby 7

Griffith— Infant's Weight Chart, .... 7
Meigs — Feeding in Early Infancy, ... 10
Powell — Essentials of Diseases of Chil-
dren, . 15

Starr — Diets for Infants and Children, . 12

DIAGNOSIS.

Cohen and Eshner — Essentials of Diag-
nosis 15

Corwin — Physical Diagnosis, 5

Vierordt — Medical Diagnosis, 14

DICTIONARIES.
The American Illustrated Medical

Dictionary 3

The American Pocket Medical Dic-

3

Dictionary, 10

tionary, . . . .
Morton — Nurses'

EYE, EAR, NOSE, AND THROAT.

An American Text-Book of Diseases

of the Eye, Ear, Nose, and Throat, . . i
De Schweinitz— Diseases of the Eye, . 6
Friedrich and Curtis — Rhinology, Lar-
yngology, and Otology, 6

Gleason — Essentials of the Ear, .... 15
Gleason — Essentials of Nose and Throat, 15
Gradle — Ear, Nose. and Throat, .... 22
Grunw^ald and Grayson — Atlas of Dis-
eases ot the Laryn.v, 16

Haab and de Schweinitz — Atlas of Ex-
ternal Diseases of the Eye, i6

Jackson — Manual of Diseases of the Eye, 8
Jackson — Essentials Diseases of Eye, . 15
Kyle — Diseases of the Nose and Throat, 9

GENITO-URINARY.

An American Text-Book of Genito-
urinary and Skin Diseases, 2

Hyde and Montgomery — Syphilis and
the Venereal Diseases, 8

Martin — Essentials of Minor Surgery,
Bandaging, and Venereal Diseases, . . 15

Mracek and Bangs — Atlas of Syphilis
and the Venereal Diseases, 16

Saundby — Renal and Urinary Diseases, 11

Senn — Genito-Urinary Tuberculosis, . . 12

Vecki — Sexual Impotence, 14

GYNECOLOGY.

American Text-Book of Gynecology, . a

Cragin — Essentials of Gynecology, ... 15

Garrigues — Diseases of Women, . ... 6

Long — Syllabus of Gynecology, .... 9

Penrose — Diseases of Women, 10

Pryor — Pelvic Inflammations, 11

Schaeffer and Norris — Atlas of Gyne-
cology, jj

HYGIENE.

Abbott — Hygiene of Transmissible Dis-
eases, 3

Bergey — Principles of Hygiene, .... 22
Pyle — Personal Hygiene, 11

MATERIA MEDICA, PHARMA-
COLOGY, and THERAPEUTICS.
An American Text-Book of Applied

Therapeutics, i

Butler — Text-Book of Materia Medica,

Therapeutics, and Pharmacology, . . 4
Morris— Ess. of M. M. and Therapeutics, 15
Saunders' Pocket Medical Formulary, . 11

Sayre — Essentials of Pharmacy 15

Sollmann — Text-Book of Pharmacology, 22
Stevens — Modern Therapeutics, .... 13
Stoney — Materia Medica for Nurses, . . 13
Thornton — Prescription-Writing, ... 13

20

MEDICAL PUBLICATIONS

21

MEDICAL JURISPRUDENCE AND
TOXICOLOGY.

Chapman— Medical Jurisprudence and
Toxicology 5

Golebiewski and Bailey — Atlas of Dis-
eases Caused by Accidents, 17

Hofmann and Peterson— Atlas of Legal
Medicine, 16

NERVOUS AND MENTAL DIS-
EASES, ETC.

Brower — Manual of Insanity, 22

Chapin — Compendium of Insanity. ... 5
Church and Peterson — Nervous and 5

Mental Diseases 5

Jakob and Fisher — Atlas of Nervous

System, 17

Shavvr — Essentials of Nervous Diseases

and Insanity, 15

NURSING.
Davis — Obstetric and Gynecologic Nurs

ingj

Griffith— The Care of the Baby, . .
Hart — Diet in Sickness and in Health,
Meigs — Feeding in Early Infancy, .
Morten — Nurses' Dictionary, . . .
Stoney — Materia Medica for Nurses,
btoney — Practical Points in Nursing, .
Stoney — Surgical Technic for Nurses,
Watson — Handbook for Nurses, . . .

OBSTETRICS.

An American Text-Book of Obstetrics,
Ashton — Essentials of Obstetrics, .
Boisliniere — Obstetric Accidents
Dorland — Modern Obstetrics, .
Hirst — Text-Book of Obstetrics,
Norris — Syllabus of Obstetrics, .
Schaeffer and Edgar — Atlas of Obstet-
rical Diagnosis and Treatment, ...

17

PATHOLOGY.

An American Text-Book of Pathology, 2
Durck and Hektoen — Atlas of Patho-
logic Histology, 16

Kalteyer — Essentials of Pathology, . . 15
Mallory and Wright — Pathological

Technique, 9

Senn — Pathology, and Surgical Treat-
ment of Tumors, 12

Stengel— Text-Book of Pathology, ... 12
\A/arren — Surgical Pathology, .... 14

PHYSIOLOGY.

American Text-Book of Physiology, . 2

Budgett — I'.sscntials of Physiology, . . 15

Raymond — Text-Book of Physiology, . 11

Stewart — Manual of Physiology, . . 13

PRACTICE OF MEDICINE.

)f Medic

An American Year-Book

and Surgery

Anders— Practice of Mcflirinc. . .
Eichhorst —Practice of Medicine,
Lockwood -Prai til o f)f Medicine,
Morris — l-'ss. iS Pr;icti<:f of Mi-dicine,
Salinger & Kalteyer— Mod. Medicine, 11
Stevens l'r.-i< lii <• i.l Mcdii Inf, . . . i^

SKIN AND VENEREAL.

An American Text-Book of Genito-
urinary and Skin Diseases, 2

Hyde and Montgomery — Syphilis and
the Venereal Diseases, 8

Martin — Essentials of Minor Surgery,
Bandaging, and Venereal Diseases, . . 15

Mracek and Stelwagon— Atlas of Dis-
eases of the Skin, 16

Stelwagon— Essentials of Diseases of
the Skin, 15

SURGERY.

An American Text-Book of Surgerj*, 2
An American Year-Book of Medicine

and Surgery, . . 3

Beck— Fractures, 4

Beck — Manual of Surgical Asepsis, . . . 4

Da Costa— Manual of Surgery-, 5

International Text-Book of Surgery, . 8

Keen— Operation Blank, 8

Keen — The Surgical Complications and

Sequels of Typhoid Fever, 8

Macdonald — Surgical Diagnosis and

Treatment, 9

Martin — Essentials of Minor Surgery,

Bandaging, and Venereal Diseases, . . 15

Martin — Essentials of Surgeiy, 15

Moore — Orthopedic Surgery, 10

Nancrede — Principles of Surgery, ... 10

Pye — Bandaging and Surgical Dressing, 11

Scudder — Treatment of Fractures, ... 12

Senn — Genito-Urinary Tuberculosis, . . 12

Senn— Practical Surgery, 12

Senn — Syllabus of Surgery, 12

Senn — Pathology and Surgical Treat-
ment of Tumors, ... 12

\Varren — Surgical Pathology and Ther-
apeutics, 14

Zuckerkandl and Da Costa — Atlas of

Operative Surgery, 16

URINE AND URINARY DISEASES.

Ogden — Clinical Examination of the

Urine, 10

Saundby — Renal and Urinary Diseases, 11
Wolf — Handbook of Urine Examination, 22
Wolff — Examination of Urine, 15

MISCELLANEOUS.

Abbott— Hygiene of Transmissible Dis-
eases, 3

Bastin — Laboratory Exercises in Bot-
any, 4

Golebiewski and Bailey— Atlas of Dis-
eases Caused by Accidents, . . . . 17
Gould and Pyle — Anomalies and Curi-
osities of .\Iedicine, 7

Grafstrom — Massage, 7

Keating — Examination for Life Insur-
ance, 8

Pyle — .V .Manual f)f Personal Hygiene, . \x
Saunders' .Medical Hand-Atlases, . 16, 17
Saunders' i'ocket Medical Formulary, . 11
Saunders' (Jiicstion-Compends, . . 14, 15
Stewart and Lawrence — Essentials of

Medical l-^lectricity, 15

Thornton — Dose-Bf>ok and Manual of

Prescriptifin-Writing 13

Van Valzah and Nisbet— Diseases of
tlx- Sioma< h 13

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ATLAS AND EPITOME pF SPECIAL PATHOLOGICAL HIS=
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By Dr. H. Durck, of Munich. Edited by LUDWIG Hektoen, M. D..
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