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HANDBOOK

OF

ANATOMY

BEING A

COMPLETE COMPEND OF ANATOMY

INCLUDING THE ANATOMY OF THE VISCERA, A CHAPTER ON
DENTAL ANATOMY, NUMEROUS TABLES, AND INCORPO-
RATING THE NEWER NOMENCLATURE ADOPTED
BY THE GERMAN ANATOMICAL SOCIETY,
GENERALLY DESIGNATED THE BASLE
NOMENCLATURE, OR BNA.

BY

JAMES K. YOUNG, M.D., F.A.O.S.

Professor of Orthopaedic Surgery, Philadelphia Polyclinic; Associate Professor

of Orthopaedic Surgery, University of Pennsylvania; Orthopaedic Surgeon

to the Philadelphia General Hospital: Fellow of the College of

Physicians, of Philadelphia; Fellow of the Philadelphia Academy

of Surgery; Fellow of the American Orthopaedic Association;

Member of the American Medical Association, etc., etc

FIFTH EDITION, REVISED AND ENLARGED

WITH 154 ENGRAVINGS, SOME IN COLORS

PHILADELPHIA

A. DAVIS COMPANY, Publishers
English Depot
Stanley Phillips, London

1918

Copyright, 1889
Copyright, 1905
Copyright, 1909
Copyright, 1913
Copyright, 1917

BY
F. A. DAVIS COMPANY

Copyright, Great Britain. All Rights Reserved

Philadelphia, Pa., U. S. A.

Press of F. A. Davis Company

1914-1916 Cherry Street

PREFACE TO FIFTH EDITION.

The demand for a new edition of the author's Handbook
of Anatomy has afforded him an opportunity to revise certain
portions of the volume, made necessary by recent advances in
anatomical studies since the publication of the fourth edition.

In order to enhance still further any value that the work
may possess, there have been some eliminations, many altera-
tions and a large number of additions. These changes, together
with the replacement of the older cuts in the chapter on Osteol-
ogy by clearer and far superior illustrations, that comprised an
osteologica] atlas in former editions, necessitated a recasting
of the entire hook.

A special "chapter devoted to Dental Anatomy, comprising
the Anatomy of the Face. Teeth and daws, properly illustrated,
lias been prepared by Joseph L. Appleton, dr.. B.S., D.D.S., of
The Thomas W. Evans .Museum and Institute of Dentistry,
I Fniversity of Pennsylvania.

In order to make the work thoroughly accurate and mod-
ern, it wa- deemed advisable to incorporate throughout the
volume the Basle nomenclature or UNA as formulated and
adopted by the German Anatomical Society. Each anatomical
name has been critically examined and its UNA equivalent
added. This is, perhaps, the only medium-sized anatomical work
that fully include- the newer terminology.

This arduous labor ha- been successfully prosecuted by Dr.
Samuel Lewald, medical and historical writer, without whose
valuable assistance this portion of the work could not haw been
accomplished.

The author trusts that these numerous changes will meet
with the approval of professors and teachers in the leading

medical and dental colleges, and that it may appeal to the

-tudeiit body in general, for whom this labor has been under

taken.

d. K. Y.
222 S... Sixteenth Street.

run

PREFACE TO FOURTH EDITION.

Although for over twenty years the book has been in con-
stant use by large numbers of students and approved by professors
and teachers in leading medical colleges and in Nurses' Training
Schools generally, comparatively few errors or omissions of im-
portance have been discovered; but in the present edition these
have all been noted and corrected. The appreciative thanks of
the author are extended to Dr. A. C. Pole, of Baltimore, for
several pertinent suggestions in the preparation of this edition.

J. K. Y.

(iv)

PREFACE TO THIRD EDITION.

In the preparation of this new edition, the author has taken
advantage of the opportunity to correct the few clerical errors
which must necessarily lie round in a comprehensive though
condensed work upon Anatomy, and to make such changes as
have become necessary through the advances of the science since
the publication of the last edition.

In the section upon the Nervous System the greatest changes
will be found, the first part having been rewritten.

In the description of the Muscular System, the regional
grouping has been retained, because it is more practical for the
student.

Attention is directed to the original colored plates of the
Arterial System which offer the most complete classification of
all the arteries in the smallest space, ami also to the original
diagrams of the sensorj tracts from spinal cord to brain, and
the motor tracts from brain to spinal cord.

The author desires to express his gratitude to the student
body of America tor their continued confidence in this early
literary effort of his, and express the hope that the present edit ion
may he as well received as the others.

J. K. V.

(v)

PREFACE TO SECOND EDITION.

The demand for a new edition has afforded an opportunity
to thoroughly revise the text and illustrations, and to add such
changes of description and nomenclature as have been intro-
duced into modern methods of teaching.

Whenever it seemed necessary or advisable sections have
been entirely rewritten, but the same attention to conciseness and
accuracy has been observed as in the former edition.

The size of the pages has been considerably enlarged and
increased in number, and the illustrations increased from 76 to
171. Many improved cuts replace those used in the former edi-
tion and full-page engraved plates have been inserted in the text
where they will be most serviceable.

In its preparation, the last editions of both Morris and Gray
have been freely consulted, so that it can be Used with either of
these standard works.

As in the former edition, although prepared particularly
for students, sufficient descriptive matter has been added to
render it valuable to the busy practitioner, particularly in the
sections upon the Yiscera, Special Senses, Vascular System, the
Nervous System, and Surgical Anatomy.

Special attention has been given to the anatomy of the brain
and nervous system, which will be found to compare favorably
with the descriptions in larger works.

The author has been much gratified to observe the tenacity
with which students and physicians have retained the work for
reference.

The author would acknowledge his obligation to Dr. Eichard
F. Gerlach, who has distinguished himself by his careful and
accurate work upon Deaver's "Surgical Anatomy," for valuable
assistance upon the revision.

J. K. Y.

(vi)

PREFACE TO FIRST EDITION.

The object of this little book is. as its title indicates, t<>
furnish a concise though complete synopsis of human anatomy
for the use of students of medicine and others.

Appreciating, from a personal contact with students, the
limited time at their disposal and the unlimited amount of
medical material to be digested, the author has endeavored, by
well-selected wood-cuts, typographical arrangement, and numer-
ous tables, to facilitate the acquisition of a subject as difficult as
it is essential, and elegance of diction has therefore been sacri-
ficed to conciseness and accuracy.

In its preparation the last edition of Gray's "Anatomy"
[edited by Keen], as the work most largely employed, has been
selected as the standard, but Leidy, Quain, Allen, Holden, Eenle,
Schaffer, Klein, Brown Aids, and others, have been freely used,
and on the special subjects Link, Spiegelberg, Savage, Sehroeder,
Budin, Treve's "Surgical Applied Anatomy." and the "Ameri-
can System of Dentistry" have been consulted. Although pre-
pared particularly for students, sufficient descriptive matter has
been added to render it valuable to the busy practitioner, par-
ticularly the section- on the Viscera, Special Senses, Vascular
System, ami Surgical Anatomy. The aim throughout has been
to make it as thoroughly complete and accurate as possible, and
at the same time readily accessible for reference or study.

The writer would acknowledge hi- obligations to Messrs.
S. X. Durborow and C. W. Holly, medical -Indents at the Uni-
versity, for assistance in the correction of proof.

.1. K. V.

(vii)

CONTENTS.

PAGE

T NTRODUCTORY 1

( >STEOLOGY 3

The Frontal Bone 8

Parietals 10

The < tecipital Bone 12

Temporals 15

The Sphenoid 20

The Ethmoid 24

The Lachrymal 26

The Malar 27

The Superior Maxilla 29

Palate Bones •'■-

The Inferior Turbinated Bonea ;{-l

The Vomer 35

The Inferior .Maxilla :!:>

The Sutures and Fontanelles 39

Fossae of skull 40

The Orbits 42

Foramina at the Base of the Skull 46

The Sternum •'-

The Ribs •v-

The Spine 5fl

The Upper Extremity (i:i

The Ann ~_[)

The Forearm '-

The Hand 7,i

The Lower Extremity sl

The Thirii

86

Th<- Patella sn

The Log w

The Fool n:<

Table of Ossification "

Abticulatioks uid Ligaments In|

The Thors i "'!l

The Pelvis "-

x CONTENTS.

PAGE

The Muscular System 128

Muscles of the Head 129

Muscles of the Neck 133

Vertebral Region 136

Muscles of the Back 138

Muscles of the Abdomen 143

Muscles of the Upper Extremity 147

Muscles of the Forearm 140

Muscles of the Hand 153

Muscles of the Lower Extremity 155

Muscles of the Leg 160

Muscles of the Foot 163

The Fascias 165

The Heart and Vascular System 170

The Circulation of the Blood 176

The Arterial System 178

Table of the Arterial System 202

The Venous System 209

The Lymphatic System 218

The Alimentary Apparatus 223

The Teeth 224

The Pharynx 230

The (Esophagus 231

The Abdomen 232

The Peritoneum 235

The Stomach 238

The. Small Intestine 240

The Large Intestine 242

The Pancreas 245

The Liver 246

The Ductless Glands '. 250

Vocal and Respiratory Apparatus 254

The Larynx 254

The Trachea and Bronchi 259

The Lungs 261

The Pleura? 264

The Mediastinum 264

The Genito-Urinary' Apparatus 266

The Kidneys 266

The Bladder 270

Male Organs . . 273

Female Organs ; 283

The Mammary Gland 292

CONTENTS.

\i

PAGE

The Nervous System 294

The Brain 298

The Cranial Nerves ;;_»:;

The Spinal ( 'ord 332

The Spinal Nerves :;.!2

Table of Spinal Nerves :;4::

The Sympathetic Nervous System 350

Organs of Special Sense 355

The Nose 355

The Eye 356

Appendages <>i the Eye ■ 372

The Ear 375

Tlic Tongue •. 388

Tlic Skin and Appendag ■ • 389

Surgical Anatomy :>!>l

Triangles <>f the Neck .' 391

Triangle in Front of Elbow-joint :!'.i4

Scarpa's Triangle 394

Axilla 395

Anatomy of I ternia 396

[schio-rectal Region and Perineum 4o-_!

Anatomy of Lateral Lithotomy 407

Dental Anatomy 4i)'.)

Index 42;;

ILLUSTRATIONS.

FIG. PAGE

1. Frontal bone, outer surface 7

2. Frontal bone, inner surface 9

3. Parietal bone, outer surface 10

-1. Parietal bone, inner surface 11

5. Occipital bone, outer surface 12

u. Occipital bone, inner surface 13

7. Left temporal bone, outer surface 15

8. Left temporal bone, inner surface 16

9. Left temporal bone, inferior surface of the petrous portion 17

10. Section of the temporal bone through the middle car, etc 19

11. Sphenoid bone, upper surface 21

12. Sphenoid bone, anterior surface 22

13. Ethmoid bone 25

14. Lachrymal bone 26

15. Xasal bone 27

16. Malar bones 2S

17. Superior maxillary bone 29

18. Superior maxillary, inner surface ' 30

19. Palate bone (viewed posteriorly) 32

20. Palate bone (inner surface) 32

21. Inferior turbinated bones 34

22. Vomer 35

23. Inferior maxillary bone 3G

24. Left half of inferior maxillary bone, inner surface 37

25. The hvoid bone 38

26. Fossae of skull 41

27. Facial portion of skull 43

28. Nasal meatuses 45

26 I'.ase of skull, external surface 47

30. Floor of the cranium 49

31. Sternum and costal cartilages 51

32. The peculiar ribs 53

33. The vertebral column, or spine 55

34. A dorsal vertebra 56

35. A cervical vertebra 57

36. The atlas 57

37. The axis 58

38. Seventh cervical, or vertebra prominens 58

39. Peculiar dorsal vertebra? 59

40. A lumbar vertebra , 60

41. The sacrum, anterior surface 61

42. The sacrum, posterior surface 62

43. The left clavicle, upper surface 64

41. The left clavicle, under surface 65

45. The scapula, anterior surface 66

46. The scapula, posterior surface 67

47. The humerus, anterior surface 69

is. The humerus, posterior surface 69

!!>. Flna and radius, anterior aspect 73

50. Radius and ulna, posterior aspect 75

51. Carpus, metacarpus, and phalanges, dorsal surface 77

Carpus, metacarpus, and phalanges, palmar surface 79

innominatum, outer -'nine. 82

54. Ok innominatum, Inner surface 83

."..",. The femur, anterior surface 87

56. The femur, posterior surface 87

.".7. The tibia and fibula, anterior surfac 91

58. The tibia and fibula, posterior Burfaci 91

50. The tarsus, metatarsus, and phalanges. Mi Si lirfai 95

60. The tarsus, metatarsus, and phalanges, plantai surface !<7

(Xi

i)

x}v ILLUSTRATIONS.

FIG. PAGE

61. The thorax Ill

62. The pelvis 112

63. The shoulder 115

64. The elbow 117

65. The knee 123

66. The knee 123

67. Muscles of the back 139

68. Muscles of the abdomen 144

69. The diaphragm 145

70. Muscles of the shoulder and arm 149

71. Triceps muscles 149

72. Posterior superficial muscles of the forearm 151

73. Muscles of the anterior femoral region 157

74. Muscles of the posterior femoral region 157

75. Anterior muscles of the leg 161

76. Posterior muscles of the leg 161

77. Right side of heart 171

78. Diagram of the foetal circulation 177

79. Arteries of the face 182

80. Internal maxillary artery 184

81. The arteries of the head and neck. (Colored) Pacing 184

82. The arteries of the upper extremity. (Colored) Facing 186

83. Abdominal aorta 195

84. The arteries of the trunk. (Colored) Facing 196

85. The arteries of the lower extremity. (Colored) Facing 198

86. Temporary teeth 226

87. Permanent teeth 227

88. Pharynx, laid open from behind 231

89. Regions of the abdomen 232

90. Abdominal viscera 235

91. The peritoneum 236

92. The liver 247

93. Transverse section of lobules of liver 24S

94. Vertical section of larynx •. 256

95. Heart and lungs 263

96. Longitudinal section of kidney : ■ 267

97. Diagram of the course of the uriniferous tubules 269

98. Male organs of generation 275

99. The testicles and epididymis 277

100. Vertical section of testicle 279

101. Internal female genitals 283

102. Female organs of generation ' 285

103. Section of an ovary 287

104. External female genitals 289

105. Surface anatomy of the myelencephalon 300

106. Left side of human cerebrum 303

107. Convolutions and fissures of the median and tentorial surfaces of the

right cerebral hemisphere 305

108. Inferior aspect of cerebral hemisphere 307 '

109. The lateral ventricles and choroid plexus 309

110. Mesial section of brain and brain stem 313

111. Interior of mesencephalon 317

112. Diagram of sensory tracts from spinal cord to brain 319

113. Diagram of motor tracts from brain to spinal cord 321

114. Scheme of the nuclei and root-fibers of the cranial nerves 323

115. Base of brain and cranial nerves 324

116. Optic, oculomotor, trachlear, and trifacial nerves Facing 324

117. Facial and auditory nerves 327

118. Glossopharyngeal, pneumogastric, spinal accessory, and hypoglossal

nei-ves 329

119. Cervical plexus and branches 333

120. Section of the spinal cord and membranes .... 334

121. Brachial plexus and branches " 335

122. Lumbar plexus and branches Facing 338

123. Sacral plexus and branches Facing 342

124. The sympathetic system Facing 350

125. The olfactory nerves and nerves of common sensation to the nose 355

126. Nasal meatuses and accessory cavities 357

127. Inner wall of orbit and adjacent parts 358

128. Horizontal section of right orbit 359

129. Anteroposterior section of eyeball 360

130. Vessels of the eye 363

ILLUSTRATIONS. xv

FIG. PACE

131. The structure of the human retina 365

132. Diagram of the retinal vessels 366

133. The orbital muscles :',Tn

1114. The ophthalmic artery and branches ::71

135. The lachrymal apparatus 374

136, External, middle, and internal ear 377

1'. The auditory ossicles 381

138. Organ of corti ::s)

139. Triangles of the neck 393

140. The axilla 395

141. Dissection of the inguinal canal ::;i7

142. Deep femoral region — the femoral vessels, etc. (McOrath) 399

143. Male perineum, superficial dissection 402

144. Male perineum, deep dissection in:!

1 15. Female perineum 405

146. Maxillary and mandibular process of first visceral arch and fronto-

nasal process 409

147. Sutures of the hard palate 410

148. Four mandibles ranging from birth to eighteen months 411

149. Muscles of expression 412

150. Tooth development 413

151. Tooth development 414

152. Root growth 417

153. Occlusal surfaces of teeth 420

154. Cross section through roots of teeth in xitu 421

Chart of cranial nerves Facing 422

INTRODUCTORY.

The term ''anatomy/' derived from the Greek dva,
"through," and T€/Ave<u, m "to cut," signifies dissection, but has
been appropriated under the general term Morphology, to the
science which treats of the apparent properties of organized
bodies. It is the science of organization and of form. Anatomy
is divided into vegetable, which treats of the structures and prop-
erties of vegetal bodies ; comparative, which treats of the anatomy
of animals; human, which treats of the anatomy of man in
a physiological or healthy state; pathological, which treats of
the anatomy of the diseased human body, etc.

Human anatomy is subdivided into general, descriptive, and
surgical.

General anatomy treats of the minute structure or physical
elements of the organs of the body. It is also called micro-
scopical anatomy, or histology. It comprises four distinct
elementary tissues : —

Epithelial, including mucous membranes, epidermis, glands, etc.
Muscular, including striated and nonstriated muscles.
Nervous, including the proper nerve elements.

Connective, including white fibrous, elastic, adipose, cartilage, and
bone.

Descriptive or special anatomy treats of the various proper-
ties of the organs arranged into systems; hence the name
systematic. It includes: —

Osteology, the anatomy of the bones.

Syndesmology, the anatomy of the joints.
Myology, the anatomy of the muscles.
Angiology, the anatomy of the vessels.
Neurology, the anatomy of the nerves.
Splanchnology, the anatomy of the viscera, etc., etc.

Surgical <»r topographical anatomy treats of the relative
position of organs to our another and to the surrounding parts
in special regions of the body, as the axilla, neck, or o-roin.

(1)

OSTEOLOGY.

The framework of the body is composed of bones, which
constitute the skeleton. This in the adult consists of 206 bones,
including the ossicula auditus: Excluding the ear ossicles, the
number is 200, or excluding also the two patella' and the hyoid
bone the muni)*']' is 197. Spine (including coccyx and sacrum)
".V>. cranium 8, face 14, ribs, sternum, and os hyoideum 26, upper
extremity 64, lower extremity 62, ear ossicles 6.

The hones of the head number 22, consisting of

Eight cranial hours-, the frontal, 2 parietal, occipital, 2 temporal,
the sphenoid and ethmoid hones; 14 facial bones, 2 lachrymal, 2 nasal,
2 malar. 2 superior maxilla'. 2 palate. 2 turbinal, 1 vomer, and 1 in-
ferior maxilla.

The hones of the trunk number 52, comprising

Twenty-six vertebrae, 7 cervical, 12 dorsal. ."> lumbar, 1 sacrum and

1 coccyx.

Twenty-six of the thorax, 7 pairs of true ribs, •"> pairs of false rilis.

2 pairs of floating ribs, the sternum and os hyoideum.

The bones of the skull, face, thorax, and vertebral column
arc known as the axial skeleton, and consist of 74 segments.

The bonea of the npper extremity number 64, comprising
on either side : —

Two shoulder, clavicle and scapula; 1 arm. humerus; 2 forearm,
radius and ulna: 8 wrist (carpus), scaphoid, semilunar, cuneiform, pisi-
form, trapezium, trapezoid, os magnum and unciform; 1!) hand, 5 meta-
carpal and 14 phalanges.

The bones of the lower extremity number 62, comprising

on either side : —

One hip, divided into 3 portion-, the ilium, ischium and pubes;
1 thigh, the femur; 2 le<_r, tibia and fibula; 1 knee, the patella; 26 foot,
7 tarsal hone-, the astragalus, os calcis, scaphoid, cuboid, external.
middle, and internal cuneiform; 5 metatarsal hones, and 14 phalanges.

The hones of the shoulder-girdle, npper extremities, pelvic
girdle, and lower extremities are known as the appendicular
skeleton, and consist of 126 Fegments. They are divided into
long, Bhort, llat or tabular and irregular.

Long bones, smcli a femur, humerus, or radius, consisl of
-hafi or diaphysis, and two extremities or epiphyses.

(3)

4 HUMAN ANATOMY.

The shaft or diaphysis is a cylindrical tube composed ex-
ternally of compact tissue and internally of cancellous tissue,
the center being hollowed out by the medullary canal.

The epiphyses, or extremities, are expanded for articulation,
and are composed of a mass of solid cancellous tissue with a
thin coating of compact tissue.

The short bones, asi tarsus or carpus, are small, compact,
irregular cubes.

Flat bones\, as those of skull and shoulder-blade, afford
extensive surfaces for protection or muscular attachment.

Under irregular or mixed bones are classed the vertebral,
sphenoid, maxillary bones, and such that could not be placed
under either of the other heads.

The surfaces of the bones are marked by certain eminences
and depressions, which have received the following names: —

An apophysis is a prominent excrescence formed directly upon
a bone, and is distinguished from

An epiphysis, which has been formed from a distinct center and
separated by cartilage, but afterward united to the bone.

A head is a rounded, smooth, articular eminence for articulation.

A condyle is an irregular prominence for muscular attachment.

A trochanter is a large prominence for the attachment of rotator
muscles.

A tuberosity is a broad, uneven eminence.

A tubercle is a small tuberosity.

A spine is a sharp-pointed eminence.

A line, or ridge, is a rough, narrow elevation, extending some
distance.

Others, from their fancied resemblance to ordinary objects,
have received the following names: —

Coronoid, like a crown; coracoid, like a crow's beak; unciform
or hamular, hook-like; malleolar, like a mallet; mastoid, nipple-like;
zygoma, yoke-like; pterygoid, wing-like; odontoid, tooth-like; spinous,
thorn-like; styloid, pen-like; rostrum, a beak; vaginal, ensheathing;
squamous, scaly; conoid, cone-like.

The cavities of bones are divided into the articular and the
non-articular.

The articular are named acetabulum, measure-like ; glenoid,
hollow; cotyloid, cup-like; facet, smooth; trochlear, pulley-
like ; alveolar, socket-like.

The non-articular cavities are named notches, fissures,
grooves, furrows, fossae, hiatus, foramina, canals, sinuses, aque-
ducts, cells, depressions, meatuses, etc.

Composition of Bone. — Adult human bones have a specific
gravity of 1.92, and are composed of about one-third (33.30)

OSTEOLOGY. 5

organic or animal matter, principally gelatin, and two-thirds
inorganic or mineral matter, as follows: —

Gelatin and blood-vessels, 33.30; phosphate, carbonate, and
fluoride of calcium, 64.34; soda, sodium chloride, and mag-
nesium phosphate. 2.36 ; total, 100.

Structure of Bone. — In structure they consist of an ivory-
like compact substance (substantia compacta) inclosing a lamel-
lar, recticular cancellous substance; also designated loose or
spongy bone (substantia spongiosa) .

They are covered with periosteum, and their cavities are
lined with endostenm and filled with medulla, or marrow.

Periosteum is a fibrovascular membrane, composed of two
layers, the outer formed chiefly of connective tissue, the inner
composed of several layers of elastic fibers, the deepest of which
is the "osteogenic/' or bone-producing layer. The tendons and
ligaments are attached to the periosteum by a mutual interlace-
ment of the fibers.

Endosteum, medullary membrane or internal periosteum, is
a delicate, highly vascular membrane lining the cylindrical
cavity of long bones.

Medulla, or bone-marrow, is of two kinds, the red in the
flat and irregular bones, and the yellow in the shafts of adult
long bones. The red marrow (medulla ossium rubra) has few
blood-vessels, but many corpuscular elements. These may be
divided into three groups: (1) red, nucleated, true "marrow-
cells," or myelocytes; (2) large, pinkish cells, "myeloplaques"
of Robin, supposed to be the source of the red blood-corpuscles or
erythroblasts ; and (3) giant cells, or "osteoclasts."

The yellow marrow (medulla ossium ftavo) or myelocytes
contains numerous blood-vessels, a few "marrow-cells," and a
large quantity of fat which imparts to it its color.

Blood-vessels of Bone. — The arteries consist of three sete:
The arteries of the (1) compact and (2) cancellous tissue are
derived chiefly from the periosteum, the latter being larger and
Less numerous. The medullary canal of long bones has (3) one
or more nutrient arteries, which penetrate tbe compaci tissue
obliquely and divide into two branches, one passing upward, the
other downward, in tbe canal. All the arteries anastomose
freely with each other.

The veins consist of three sets also: 1. Tbe veins of the
compact substance are small and join the periosteum. 2. The
veins of the cancellous 1 issue do not accompany the arteries, but
in certain Localities form large, tortuous channels, as in the
diploic jreins of ilie cranium. In the long bones they emerge

.(3 HUMAN ANATOMY.

at the ends, near the articular surfaces. 3. The nutrient arteries
are accompanied by one or more large veins, which emerge at
the nutrient foramen.

Lymphatics and nerves are numerous in the periosteum and
are also found in the substance of the bone.

Microscopic Appearance. — Microscopically, bone-tissue con-
sists of concentric layers or lamella, arranged, about the course
of a vascular or Haversian canal /4eooo mcn i11 diameter. In
and between these plates of bone-tissue are minute cavities, or
lacuna?, each containing a bone-cell, or "osteoblast/' and from
which diverge in every direction minute canals, or canaliculi,
connecting the lacunas with each other and with the Haversian
canals. Each canaliculus contains an artery, vein, and lym-
phatic (Schaffer). In this manner every part of the osseous
substance communicates.

Development. — The development of bone is effected in two
ways: (1) from cartilage, the intracartilaginous; (2) from
membrane, the intramembranous ; the former occurring at the
base of the skull for the protection of vital centers, or m the
extremities to secure rigidity of the parts.

In the intracartilaginous the parts are first formed in
cartilage and then converted into bone. The process is as fol-
lows: The cartilage cells at the "center of ossification" become
enlarged and arranged in rows. The cartilaginous matrix also
increases and separates the cells. Lime salts are deposited be-
tween the rows of cells, inclosing them in oblong spaces called
primary areola'. -

Blood-vessels from the dee}} or osteogenic layer of the peri-
osteum, carrying numerous osteoblasts (bone-forming cells)
and osteoclasts (bone-absorbing cells) pass into the area of
calcified cartilage (center of ossification). The osteoblasts re-
place the calcified cartilage, which is absorbed, with new bone,
which latter is absorbed in part (tunneled) by the osteoclasts to
form the medullary spaces or marrow cavity.

■The walls of the spaces are gradually thickened by suc-
cessive layers of osteoblasts, forming lamellae of bone, till noth-
ing remains but a channel — the Haversian canal.

The perichondrium having been in the mean time con-
verted into periosteum, the osteogenic, or vascular, layer of this
membrane furnishes a layer of osteoblasts that form enveloping,
circumferential layers of bone.

Thus, from the osteoblasts all the structures of bone are
produced; the remains of a group of cells constitute an Haver-
sian canal, the layers deposited by them and the adjacent cells,

OSTEOLOGY. 7

the lamella1, and the isulated, persistent cells (osteoblasts) form
the contents of the lacunae, or "true bone-cells/' with their nu-
trient canaliculi diverging from them.

In the intramembranous form the parts are first formed in
membrane, and from one or more centers of ossification lime
salts are deposited in radiating spiculae, or osteogenic fibers, in-
closing the osteoblasts.

From these fibers the process spreads, and vessels from the
neighboring parts pass into it and form Haversian canals.

Fig. L
Frontal bone, outer surface.

The formation of the lamella! and the lacunae is essentially
the same as in the intracartilaginous, and in most bones both
processes go on simultaneously.

Ossification appears first in the clavicle and inferior maxilla
(from fifth to seventh week) and last in the pisiform bone
(twelfth year). The epiphyses ossify from birth and unite from
the age of puberty on to maturity, in reverse order to the ap-
pearance of ossification, being regulated, apparently, by the
direction of the nutrient artery in the upper extremity toward
the elbow and in the lower extremity from the knee. The only
exception to this rule ie the lower end of the fibula, which ossifies
and also becomee united before the upper (vide Table of <K-ili

8

HUMAN ANATOMY.

cation). In bones with only one epiphysis the artery is directed
toward the other extremity.

Growth of Bones. — Long bones grow in thickness from the
periosteum and in length from the cartilage between the epiph-
yses and the shaft near the extremities. The medullary cavity
is at first solid and grows by absorption of the cancellous tissue
by the giant cells, or osteoblasts.

Flat bones grow in thickness from the periosteum and in
surface from the borders. Short bones grow from the center
or centers of ossification in all directions.

THE CRANIAL BONES.

The cranial bones are eight in number : —

1 Frontal, 2 Temporal,

2 Parietal, 1 Sphenoid,
1 Occipital, 1 Ethmoid.

The frontal bone (os frontal e) forms the anterior por-
tion of the cranium, and consists of two portions, a vertical or
frontal portion and a horizontal or orbitonasal portion.

The vertical portion consists of two surfaces, external and
internal.

The external surface {fades frontalis) is convex, and pre-
sents the frontal eminence {tuber frontale) on either side of the
median line, the superciliary ridges (arcus superciliaris) pro-
duced by the frontal, sinuses, beneath, below which is the
supraorbital arch {mar go supraorbitalis) , forming the upper
boundary of the orbit, and terminating on either side in the
external angular process {processus zygomaticus), articulating
with the malar bone, and the internal angular process, articulat-
ing with the lachrymal bone, and having at its inner third a
notch or foramen, the supraorbital foramen, for passage of
supraorbital artery, nerve and vein.

Ascending from the external angular process is the tem-
poral riclge {Unea temporalis) for attachment of temporal fascia.
Between the internal angular processes is the nasal notch, for
articulation with the nasal bone, and nasal process of superior
maxilla, terminating below in the nasal spine {spina nasalis or
frontalis) , and above it projects the nasal eminence, or glabella,
marking the location of the frontal sinuses.

The posterior or internal surface (cerebral surface, or
fades cerebralis) is concave and lodges the anterior lobes of
the brain.

OSTEOLOGY.

9

In the median line is the frontal crest (crista frontalis),
which gives attachment to the J'alx cerebri and terminates he-
low in a foramen, the foramen caecum, for passage of a small
vein from the nose to the longitudinal sinus. The crest is
grooved for longitudinal sinus, and has on either side of it
depressions for the Pacchionian hodies. This surface is also
grooved for anterior meningeal arteries.

The horizontal portion or orbital portion (pars orbitalis)
consists of an external and internal (cerehral surface, fades
cerehralix) surface.

vitA Sup.MaxiU

FrontaX Si%u*

I Ko-jm ndtd 6tu« »f Xrual SpVTtPf
J^rmin.j p*H tf jfcf tf Rett

Pig. 2.
Frontal bone, inner surface.

The external surface (fades orbitalis) is concave, to form
the roof of the orbit, and separated from the opposite side by
tin- ethmoidal notch.

To the outer side is a deep depression for the lachrymal
gland, the Lachrymal fossa (fossa glandula lacrimalis) , and to
the inner side a slight one, the trochlear fossa (fovea tro-
chlearis), for the pulley of superior oblique.

On the margin of the orbital plate are two notches con-
verted into foramina by articulation with the ethmoid, the an-
terior ethmoidal canal (foramen, ethmoidal e anterius), for
passage of nasal nerve and anterior ethmoidal vessels, and the
posterior ethmoidal canal (foramen ethmoidals postervus), for
passage of posterior ethmoidal vessels.

10

HUMAN ANATOMY.

The internal surface is marked by the convolutions of the
anterior lobes of the brain.

Between the two plates of the vertebral portion are the
frontal sinuses, two irregular cavities lined with mucous: mem-
brane and opening into the middle meatus of the nose on either
side by the infunclibulum (infundibulum ethmoidal e).

It articulates with twelve bones: two parietal, sphenoid,
ethmoid, nasal, superior maxillary, lachrymal, and malar.

%§$0^

Fig. 3.
Parietal bone, outer surface.

Its muscular attachments are three pairs : corrugator super-
cilii, orbicularis palpebrarum, and temporal.

It is. developed from membrane by two ossific centers, one
for each lateral half.

Parietals (os parietale). — These are two quadrilateral
bones forming the superior and lateral walls of the cranium.
Each bone consists of two surfaces, four borders, and four
angles.

The external surface (fades parietalis) is convex and pre-
sents the parietal eminence (tuber parietale) "a little above the
middle, marking the original center of ossification, the temporal
ridge (linea temporalis) , crossing about the center for attach-
ment of the temporal fascia, and the parietal foramen (foramen

OSTEOLOGY

11

parietdle), near the superior border or sagittal suture, for pass-
a vein, the emissary vein of Santorini, to the longi-
tudinal sinus.

The internal surface or cerebral surface (fades cerebralis)
is concave, and presents furroivs for the branches of the menin-
geal arteries, depressions | foveolce granulares \ Pacchioni] ) foT
cerebral convolutions, and Pacchionian bodies.

A half-groove (sulcus sagittalis) along the superior border
for longitudinal sinus, and

Anal*

\ A*t. Sup.

AniTiifcnXnyle

FlO. 4.
Parietal bone, inner surface.

A groove (sulcus transversus) near the posterior inferior
angle for the lateral sinus.

The superior border or sagittal margin (margo sagittalis)
articulates with its fellow of the opposite side, forming the
Bagittal suture;

The inferior border — also called the squamous margin
(margo squamosus) — articulates from before backward with the
sphenoid, squamous and mastoid portions of temporal bonee ;

The anterior border -also called frontal margin (margo
frontalis) — forms with the frontal hone the coronal suture, and

The posterior border or occipital margin (margo occip-
italis) form- with the occipital hone the lainhdoid suture.

12

HUMAN ANATOMY.

Of the angles, the anterior inferior (angulus sphenoidalis)
is the only important one, being longer and grooved internally
by the middle meningeal artery.

It articulates with five bones — frontal, sphenoid, temporal,
occipital, and opposite parietal bones.

It has but one muscle attached — the temporal.

It is developed from an ossific center.

The occipital bone (os occipitalis) forms the posterior
inferior portion of the cranium. It presents two surfaces, four
angles-, and four borders.

Fig. 5.
Occipital bone, outer surface.

The external and posterior surface is irregularly convex,
and presents

The occipital protuberance or inion (protuherantia occip-
italis externa), for insertion of ligamentum nucha, descending
from which to the foramen magnum is

The occipital crest {crista occipitalis externa) for tendin-
ous attachment, and diverging on either side, above and below,
are

The superior curved or superior nuchal line (linea nuchte
suprcema) for attachment of occipitofrontalis, trapezius, and
other muscles; and

OSTEOLOGY

13

The inferior curved or interior nuchal line (linea nucha'
inferior) for attachment of rectus capitis posticus, major and
minor.

Anteriorly it presents a large aperture,

The foramen magnum (foramen occipiMe magnum), trans-
mitting the medulla oblongata and its coverings, the vertebral
arteries, and the spinal accessory nerves.

On either side of the foramen magnum are the condvlic or
lateral portions (paries laterales) hearing the condyles (con-

Sufierier Ati^lt

J»f'r,J A„slf V*V

Fig. 6.
Occipital bone, inner surface.

dylus occipitalis) for articulation with the atlas, the inner bor-
deT of each condyle presenting a tubercle for the check liga-
ment.

Externally to each condyle are the jugular processes
(processus jugularis) affording attachment for the rectus capitis
lateralis, and forming by its articulation with the fibrous portion
.,(' ihc temporal bone the jugular foramen, or foramen lacerum
posterius, transmitting the internal jugular vein, glossopharyn-
geal, pneumogastric and spinal accessory nerve-, and menin-
geal branches of the ascending pharyngeal and occipital arteries.

In front of the condyles on either side are the openings of

14- . HUMAN ANATOMY.

the anterior condyloid foramen (canalis hypoglossi), for pass-
age of hypoglossal nerve and meningeal branch from the
ascending rmaryngeal artery; and behind, the posterior con-
dyloid foramen (canalis condyloideus) , for passage of a small
vein to the lateral sinus.

In front of the foramen magnum is the basilar process
(pars basilaris), articulating with the sphenoid bone, and
grooved on its under surface by the pharyngeal spine (tuber-
culum pliaryngeum) for the insertion of the tendinous raphe
and superior constrictor of the pharynx.

The internal or cerebral surface is irregularly concave and
divided by a crucial ridge, or occipital cross, into four fossae,
the upper, for the posterior lobes of the cerebrum, and the lower,
for the lateral lobes of the cerebellum. Its center is marked by
an eminence, the internal occipital protuberance (protuberantia
occipitalis interna), which is hollowed out to correspond to the
torcular Herophili, or confluence of the sinuses.

The upper division of the crucial ridge affords attachment
for the falx cerebri, being grooved for the great longitudinal
sinus; the lower extremity, called also the internal occipital
crest (crista occipitalis interna), affords attachment for the falx
cerebelli, being grooved for the occipital sinus; and the lateral
divisions afford attachment for the tentorium cerebelli and are
grooved for the lateral sinuses.

The internal surfaces of the jugular processes are grooved
for the lateral sinuses.

In front of the foramen magnum is the basilar groove
(clivus) lodging the medulla oblongata and part of 'the pons
Varolii. Its lateral borders (the basilar process) are grooved
(sulcus petrosus inferior) for the inferior petrosal sinus.

The superior angle articulates with the parietal bones, the
inferior angle articulates with the sphenoid, and the lateral
angles are wedged in between the mastoid portion of the tem-
poral and the posterior inferior angle of the parietal.

This bone has four foramina — foramen magnum, anterior
and posterior condyloid, and foramen lacerum posterius.

It articulates with six bones — two parietal, two temporal,
the sphenoid and the atlas.

The muscular attachments are twelve (12) : occipitofron-
talis, trapezius, sternomastoid, complexus, splenitis capitis, ob-
liquus superior, rectus capitis posticus major and minor, rectus
lateralis, rectus antieus major and minor and constrictor
pharyngis superior.

It is developed from seven (7) ossific centers: four for

OSTEOID h,y

15

the tabular, or supraoccipital, or occipital portion proper; one
for each condyloid, or external occipital portion, and one for the
basilar, or basioccipital port ion.

Temporals (os temporale). — These are situated at the side
and base of the cranium, and consist of three portions — the
squamous, mastoid and petrous.

The squamous portion (squama temporalis) is scale-like,
and overlaps the parietal bone. Its external surface (fades
temporalis), convex behind, concave in front, presents from be-
fore backward the following: —

Fig. 7.
Left temporal bone, outer surface.

The zygoma, or zygomatic process (processus zygomaticus),
an arched process of bone articulating with the zygomatic proc-
ess of til.- malar bone, affording attachment above to the
temporal fascia and below to the masseter muscle. It is con-
nected to the body of the bone by three roots, the anterior root
of which ends in the eminentia articularis (tuberculum arhc-
idare), a process of bone in front of the glenoid cavity, and
presents »i its junction a tubercle for the external lateral liga-
ment; the middle root, also called the postglenoid process or
tubercle, terminates at the Glaserian fissure (fissura petro-
tympanic [Glasen]), and the posterior root forma the posterior
portion of temporal ridge and gives attachment to the retrahens
aurem,

16

HUMAN ANATOMY.

The glenoid fossa (mandibular) is a marked depression
hollowed out for articulation of the condyle of the lower jaw.
It is bounded in front by the eminentia articularis, to the outer
side by the middle root, and behind by the vaginal process
(vagina processus styloidei). It is divided into two portions by
the Glaserian fissure, the anterior being separated from the
auditory process by the postglenoid tubercle — rudimentary in
man — and the posterior being formed by the tympanic plate, a
thin plate of bone forming the front wall of the tympanum.

Beprcenun far Dara-malrr
BtaBUfi AueUtvrutM vntnnvu*

"n,i (Jr«»6 ...

'E-miwute for Superior J£mc/v^tra^lar t«aw
^\^* Hiatus FaUopil
^ ^^Ojicnijui for SitfaMer Pctross&lforif*

Dcnresaum far Cwstert^an gaitglum

UrutU vasztd Uu-ouyh Caraud OiMal

Fig. 8.
Left temporal bone, inner surface.

The Glaserian fissure communicates with the tympanum,
transmits the tympanic branch of the internal maxillary artery,
and lodges the processus gracilis of the malleus.

In the angle between the squamous and petrous portions the
chorda tympani nerve passes from the tympanum through the
canal of Huguier (canaliculus clwrdce tympani).

The internal surface (cerebral surface, fades cereoralis) of
the squamous portion presents the markings of the convolu-
tions, and grooves for the ramifications of the middle meningeal
artery. The mastoid portion (pars mastoidea) is convex, rough,
and nipple-like, and presents, externally, the following: —

The mastoid foramen (foramen mastoideum) near the pos-

OSTEOLOGY.

17

terior border, transmits a branch of the occipital artery to the
dura mater and a small vein to the lateral sinus;

The mastoid process (processus mastoideus) , a prominent
projection, composed of the mastoid cells (celluke mastoid ew) ,
and affording insertion for the splenitis capitis, stemomastoid
and trachelomastoid muscles.

To its inner side is a groove, the digastric groove, also
called digastric fossa (incisura mastoidal), for attachment of

(TYLO-PMAKYNOCOt

Rough Quadrilateral 'Sulfate
Vpt^una of carotid cm,ol
Canaljbr Jacobxon't nerx't
Anus/bic.rus Corhlatz
Canal for Arnold'* nerve
Jvg>u7ar fuasa
Vagi naT jjroceti
Styloid prueeet
jStylo-'masroi-a7 foramen
Jxiavlnr Si'rfaee
Auricular future

FIG. 9.
Left temporal bone, inferior surface of the petrous portion.

the digastric muscle, and still more internally the occipital
groove (sulcus a. occipitalis) for the accommodation of the
occipital artery.

The internal surface is concave, and presents a groove, the
fossa ngmoidea (sulcus si'jmoideus) for the lateral sinus, in the
bottom of which is the opening of the mastoid foramen (foramen
mastoideum ) .

The petrous portion (pars petrosa pyramis) is pyramidal
in shape, intensely hard, and contains the internal ear. It pro-

2

18

HUMAN ANATOMY.

jects downward, forward and inward, and presents for exami-
nation a superior, posterior and inferior surface.

The superior or anterior surface (fades anterior pyramidis)
is united to the squamous portion by the temporal suture and
presents the following- : —

An eminence (eminentia arcuata), marking the position of
the superior semicircular canal;

A depression, forming the roof of the tympanum;

The hiatus Fallopii (hiatus canalis facialis), transmitting
a branch of the middle meningeal artery and the petrosal branch
of the A^idian nerve to the aqueduct of Fallopius;

Foramen (apertura superior canaliculi tympanici) for the
smaller petrosal nerve;

Orifice of the carotid canal, transmitting the carotid plexus
of the sympathetic and the internal carotid artery; and

Depression (impressio trigemini) for Gasserian ganglion
of the trifacial nerve.

The posterior surface (fades posterior pyramidis) presents
about its middle

The meatus auditorius internus (meatus acusticus inter-
ims), at the bottom of which is the lamina cribrosa, a perpendic-
ular plate of bone, and numerous foramina for the exit of the
auditory nerve and the auditory branch of the basilar artery,
one of which is the commencement of the aquaeductus Fallopii
(canalis facialis) for the facial nerve.

Posteriorly to the internal meatus is the aquaductus ves-
tibidi, lodging a process of dura mater, and transmitting an
artery and vein, and between them another small depression for"
the same purpose.

The inferior or basilar surface (fades inferior pyramidis)
presents, from within outward, the following : —

A rough, quadrilateral surface, for attachment of the tensor
tympani and levator palati muscles;

The opening of the carotid canal (foramen caroticum ex-
ternum), transmitting the carotid plexus of the sympathetic
and the internal carotid artery;

Aqiuzductus cochlece (apertura externa canaliculi cochlea),
transmitting a vein to the internal jugular vein from the
cochlea ;

Jugular fossa (fossa jugularis), forming the jugular fora-
men (foramen lacerum posterius) by articulation with the
occipital bone, and transmitting the internal jugular vein, the
glossopharyngeal, pneumogastric, and spinal accessory nerves.

OSTEOID >GY.

19

and meningeal branches "J' the ascending pharyngeal and occip-
ital aiter - .

Foramen for Jacobsons nerve, the tympanic branch of the
_ ssopharyngeal (ft. tympanicus) ;

Foramen for entrance of Arnold's nerve, the auricular
branch of the pneumogastric ;

Jugular surface for articulation with jugular process on oc-
cipital bone ;

The vaginal process (vagina processus styloidea), extend-
ing from the mastoid process to the carotid canal, and ensheath-
ing

Fig. 10.

Section of the temporal bone (natural size) through the middle
<-ar. Fallopian canal, mastoid antrum, and cells, showing dense bone
between the antrum and cells, with no communication between them:
1, drumhead: L'. tip of the mallet handle; 3, anvil, showing the long
crus at the right for articulation with the stirrup, and the short proc-
t the left which serves the purpose of an anchor to the bone; 4,
head of the mallet; '■>. tensor tympani muscle and tendon; 6, dense
bone where pneumatic spaces are usually found; 7, pneumatic cells in
the tip of the mastoid process: 8, Fallopian canal, for the facial nerve;
9, the Btirrup. At the right of 9 and at the left of the anvil is the
aditus ad antrum, connecting the tympanum with the antrum.

The styloid process (processus styloideus), affording at-

lacluiiciit for the stylomaxillary and stylohyoid ligaments and

bylohyoideus, stylopharyngeus and styloglossus muscles;

The stylomastoid foramen (foramen stylomasioideum) , for
exit of facial nerve;

The auricular fissure (fissura tympanomastoidea) , for the
exil of Arnold's aerve, the auricular branch of the pneumo-

ric.

The base of the petrous port ion presents

The- external auditory meatus (meatus acusticus externus),

• anal leading into the t) mpanum, and

20 HUMAN ANATOMY.

The auditory process, a lamina of bone forming the greater
part of its walls.

Borders. — The superior border (angulus superior pyram-
idis) affords attachment to the tentorium cerebelli, and has a
groove for the superior petrosal sinus. The posterior border
{angulus posterior pyramidis) forms part of the jugular fossa
(fossa jugularis). The anterior border (angulus anterior py-
ramidis) articulates with the spinous process of the sphenoid.
Between the squamous and petrous portions may be seen the
opening of the canalis musculotubarius; this canal is found
either completely or partially divided by an osseous lamina,
separated by the processus cochleariformis (septum canalis mus-
cuiotuharii), for the tensor tympani muscle above and the
Eustachian tube below.

Muscular attachments are fifteen: —

To the squamous portion, 2 — the temporal and masseter;
to the mastoid portion, 6 — -sternomastoid, occipitofrontal!?,
splenitis capitis, trachelornastoid, retrahens aurem, and digas-
tricus; to the styloid portion, 3— stylohyoideus, stylopharyn-
geus and styloglossus; and to the petrous portion, 4 — levator
palati, tensor palati, tensor tympani and stapedius.

Its ossific centers are ten (10), 1 for the squamous portion,
including the zygoma, 1 for auditory process, 6 for' petrous and
mastoid portions, and 2 for the styloid process.

The sphenoid (os sphenoidale) is wedged in between the
bones at the base of the skull anteriorly and resembles a bat
with extended wings. It consists of

A body, 2 Lesser wings, and

2 Greater wings, 2 Pterygoid processes.

It presents

12 Foramina, 12 Pairs of muscles, and

12 Articulations, 14 Centers of ossification,

and is in every respect the most important bone of the cranium,
entering into the formation of

5 Cavities — (2) Zygomatic,

(1) Anterior cerebral, (3) Sphenomaxillary,

(2) Middle cerebral, (4) Nasal, and

(3) Orbital, 3 Fissures —

.(4) Pharyngeal, (1) Sphenomaxillary,

(5) Nasal, (2)' Pterygomaxillary, and

4 Fossce — (3) Sphenoidal or foramen
( 1 ) Temporal, lacerum anterior.

OSTEOLOCY.

21

The body (corpus) is a hollow cube and presents upper,
lower, anterior and posterior surfaces.

The upper surface (fades cerebralis) of the body presents
from before backward the following points: —

Ethmoidal spine (s/rina ethmoidalis) , for articulation with
the cribriform plate of the ethmoid ;

Optic groove (sulcus chiasmal is), lodging the optic com-
missure and terminating in the optic foramen;

Olivary process (iuuerculum sella'), a small, olive-like
eminence behind the optic groove;

Pituitary fossa or sella turcica (fossa hypohyseos), for the
pituitary body;

tliidlt Ck^ld prxcj

P^/CTzrr CUiwutprocCM \ •M™^ •T/'W
~"-^_^^_^ ** \ , \ Groove jar

Fig. 11.
Sphenoid bone, upper surface.

Middle clinoid processes (processus dinoidei medii), one
on either side bounding the pituitary fossa;

Dorsum sella, or dorsum ephippii, a quadrilateral plate of
bone, bounding the pituitary fossa behind, and notched on either
side for the passage of the sixth cranial nerves;

Posterior clinoid processes (processus clinoideus posterior)
are the terminations of the dorsum sella1 on either side and
afford attachment to the tentorium cerebelli;

Declivity, or clivus Blumenbachii (clivus), supporting the
upper part of the pons Varolii;

Carotid or cavernous groove (sulcus caroticus), lodging the
cavernous -inns and the internal carotid artery;

Lingula (lingtUa sphenoidalis) , a ridge of bone to the outer
side of the cavernous sinus.

22

HUMAN ANATOMY.

The lower surface presents : —

Rostrum {rostrum sphenoidalis) , the continuation down-
ward of the ethmoidal crest, for articulation with the ala? of
the vomer;

Vaginal processes, a thin plate of hone on either side artic-
ulating with the edges of the vomer; and

Groove (sulcus pterygopalatinus), converted into the
pterygopalatine canal by articulation with the sphenoidal
process of the palate bone for transmission of the pharyngeal
nerve and pterygopalatine vessels.

Jtery>joid R

LAXATOR TYMPANI

Internal Pterygoid, yilate

HumuJxi.r Uroctst

Fig. 12.
Sphenoid bone, anterior surface.

The anterior surface presents : —

Ethmoidal crest or sphenoidal crest (crista sphenoidalis),
a thin plate of bone articulating with the ethmoid;

Openings of sphenoidal cells or sinuses (sinus sphenoidal 'es)
partially closed by the sphenoidal turbinated bones or pyramids
of Wistar (conchce sphenoid ales), two curved plates of bone ab-
sent in infancy, but derived as a pair of cones from the ethmoid;
The sphenoidal cells open into the superior meatus of the nose,
but occasionally into the posterior ethmoidal sinuses.

The posterior surface articulates with the basilar process of
the occipital and becomes united to it between the eighteenth
and twenty-fifth year.

OSTEOLOGY. 23

GEEATEK OR TEMPORAL WINGS OF THE SPHENOID
(AL.K MAiiX.E).

The superior surfaces (facie* cerebralis) of the great wing,
deeply concave, forms part of middle fossa of skull, and pre-
sents the following : —

Foramen rot and urn, for second division of fifth nerve; fora-
men ocale, for third division of fifth, small meningeal artery,
and small petrosal nerve; foramen Vesalii, for small vein, and
foramen spinosum, for passage of middle meningeal artery.

The exterior surface is convex and presents: —

Pterygoid ridge or infratemporal crest (crista infratem-
poral^), dividing the hone into two portions;

Spinous process, for attachment of tensor palati muscle, and
the internal lateral ligament of the lower jaw.

The anterior or orbital surface (fades orbitalis) enters into
the formation of the orbit and presents numerous external
orbital foramina for passage of branches of the deep temporal
arteries.

The circumference of the greater wing forms part of the
sphenoidal fissure and articulates with the frontal bone in front
and laterally with the parietal, squamous and petrous portions
of the temporal bone.

The lesser or orbital wings (alee parvce), or processes of
Ingrassias, project on either side from the superior surface of
the body, to which they are attached by two roots.

The upper surface forms part of the anterior fossa of the
skull. The lower surface forms part of the orbit and the upper
border of the sphenoidal fissure, or foramen lacerum anterius
{fissiira orbitalis superior), transmitting the third", fourth and
ophthalmic divisions of the fifth and the sixth cranial nerve,
orbital branch of the middle meningeal artery, a recurrent
branch of the lachrymal artery, the ophthalmic vein, and fila-
ment- from the cavernous plexus.

The anterior clinoid process (processus clinoideus anterior)
i- formed by the inner extremity of the posterior border.

Between the two roots is the optic foramen (foramen
opticum), transmitting the optic nerve and ophthalmic artery.

The pterygoid processes (processus pterygoidei) are two
wing-like processes descending from the junction of the greater
wings with the body.

Each process presents the following: —

An externa] pterygoid plate (luminu lateralis processus

pterygoidei)} for attachment oi the external pterygoid muscle;

g4 HUMAN ANATOMY.

The pterygoid fossa (fossa pterygoidei) lies between the
two plates and affords attachment for the internal pterygoid
muscle.

The internal pterygoid plate (lamina medialis processus
pterygoidei), terminating below in a hook-like process — the
hamular process (hamulus pterygoideus) — for the tendon of the
tensor palati nrascle.

The scaphoid fossa (fossa scaphoid ea) , at the base of the
internal plate, affording origin for the tensor palati muscle and
presenting just above it, the posterior opening of the Vidian
canal (canalis pterygoideus [Vidii]) for the Vidian vessels and
nerves.

An angular interval between the two plates articulates with
tuberosity or pterygoid process of the palate bone.

The foramina are: Opticum, lacerum anterius, rotundum,
Vesalii, ovale, spinosum, and two canals — Vidian and pterygo-
palatine; articulates with twelve bones — two malar, two palate,
vomer, and all of cranium. Its muscular attachments are
eleven pairs — external and internal pterygoid, temporal, tensor
palati, superior constrictor, levator palpebral, obliquus superior;
superior, inferior, internal and external recti. Its ossific cen-
ters are fourteen, as follows: Body, 2 anterior and 2 posterior;
external pterygoid plates and greater wings, 2 ; internal ptery-
goid plates, 2; lingula, 2; lesser Avings, 2; sphenoturbinals, 2.

The ethmoid (os etlimoidale) is a spongy, cubical bone,
consisting of a perpendicular lamella, a horizontal or cribri-
form, plate, and two lateral masses.

The horizontal or cribriform plate (lamina cribrosa) pre-
sents from before backward the following points: —

Two projections (processus alares) completing the foramen
coBCum, the commencement of the longitudinal sinus;

Crista galli, affording attachment to the falx cerebri;

Foramina cribrosa, three rows, transmitting filaments of
the olfactory body;

Fissure for passage of the nasal branch of the ophthalmic
nerve.

The perpendicular plate (lamina perpendicularis, or mes-
ethmoid) assists in forming the nasal septum, articulating in
front with the crest of the nasal bones and the frontal bone and
behind with the sphenoid and vomer. It is usually inclined
to one side.

The lateral masses — labyrinth (labyrinthus etlimoidalis) —
are composed of the ethmoidal cells.

OSTEOLOGY.

The upper surface presents two notches, converted into fo-
ramina by articulation with the frontal bone —

The anterior ethmoidal foramen (caimUs ethmoidalis an-
teriiis), transmitting the anterior ethmoidal artery and nasal
nerve, and

The posterior ethmoidal foramen (canalis ethmoidalis pos-
terius), transmitting the posterior ethmoidal artery and vein.

The outer surface presents

The os phi mi tit (lamina papi/racea), a smooth plate of bone
forming the inner wall of the orbit, and projecting downward
from it is

toitk mf.'turbinateJ 6.

Fig. 13.
Ethmoid bone.

The unciform process (processus uncinatus), a hook-like
plate of bone closing the upper part of the opening of the
antrum.

The inner surface forms part of the nasal fossa, and presents

The superior turbinated bone (concha nasalis superior),
forming the upper boundary of the superior meatus (meatus
nasi superior), into which open the sphenoidal and posterior
ethmoidal cell-, and the

.Middle turbinated bone or the inferior ethmoidal turbinate
bone (concha nasalis media), forming the upper boundary of
the middle meatus of the nose, into which open the anterior
ethmoidal cells, the frontal cells through the infundibulum
(infundihuluni ethmoidale) and the antrum Eighmorianum
| imi.s in n. i iHuris).

26 HUMAN ANATOMY.

It articulates with fifteen bones — -two sphenoidal turbinated,
sphenoid, frontal, and eleven of the face, the two nasal, two
lachrymal, two superior maxilla?, two palate, two inferior turbi-
nated and the vomer.

It has no muscular attachments.

Its ossific centers are three — one for the lamella and one for
each lateral mass.

BONES OF THE EACE (OSSA FACIEI).

The bones of the face are fourteen in number — six pairs and
two single bones: Two lachrymal, two nasal, two malar, two

viihFrontdl

Fig. 14.
Lachrymal bone.

superior maxillary, two palate, two turbinal, one vomer and one
inferior maxillary.

The lachrymal (os lacrimale) are two small, thin bones
forming part of the inner wall of the orbit and the lachrymo-
nasal duct, and named, from their resemblance to a finger-nail,
the ossa" unguis.

Each presents externally : —

The lachrymal crest (crista lacrimdlis posterior) affords
attachment for the tensor tarsi and separates the anterior sur-
face from the groove;

The groove forms part of the lachrymal groove and lodges
the lachrymal sac;

The hamular process (hamulus lacrimalis), or, when sep-
arate, called the lesser lachrymal bone, projects downward and
articulates with the lachrymal tubercle of the superior maxilla.

OSTEOLOGY

v;

Internally : —

A furrow, corresponding to the lachrymal crest on the ex-
ternal surface ;

The internal surface enters into the formation of the middle
meatus, closing in the anterior ethmoidal cells.

It articulates with four bones — the frontal, ethmoid, supe-
rior maxilla and inferior turbinated.

The only muscular attachment is the tensor tarsi.

It is developed from one ossific center.

The nasal hones (ossa nasalia) are two irregularly quad-
rate bones forming together the bridge of the misc.

The outer surface, covered by the compressor nasi and pyr-
amidalis nasi muscles, presents

A foramen (foramen nasale), transmitting a small vein.

The inner surface presents

u-iiA Frontal B.

—Ojjpoiit* bone.

(Outer surface.)

Fig. 15.
Nasal bones.

with

Tro ntaZ Szn7te.

orest

<wifh
'RrpendicuZar

jPlaU rfEthmoid,

groove for natal nervo

(Inner surface.)

A groove or canal lor a branch of the nasal nerve.

The inferior border, the most important, has attached to it
the lateral cartilage of the nose, and presents

A spine, forming, with its fellow, the nasal angle, a notch
for exit of the branch of the nasal nerve which grooves the pos-
terior surface.

It articulates with four hones — frontal, ethmoid, superior

maxilla, and it- fellow.

It has no muscular attachments. It is developed from one
center.

Tin; malar bones (08 zygomaticum) are two quadrilateral
bonee forming the prominence of the cheek. They enter into
the formation of the orbit and the zygomatic and temporal fossa'.

Each hone ha.- four processes — zygomatic, maxillary, fron-
tal and orbital.

28

HUMAN ANATOMY.

The external or malar surface (fades malaris) has attached
to it the zygomatic muscles (major and minor), and presents

A foramen (foramen zygomaticofaciale) to its outer side
for the malar branch of the temporomalar nerve and a fora-
men to its inner side for the temporal branch of the temporo-
malar.

The internal or temporal surface (fades temporalis) artic-
ulates with the superior maxilla, has attached to it the masseter
and temporal muscles, and presents the internal openings of the
foramen given above.

The zygomatic process (processus temporalis) forms, with
the zygomatic process of the temporal bone, the zygoma.

£r£^*-E£

(Outer surface.)

Pig. 16.
Malar bones.

(Inner surface.)

The maxillary process is triangular and roughened for ar-
ticulation with the superior maxilla.

The frontal process (processus frontosphenoidalis) is artic-
ulated with the external angular process of the temporal bone.

The orbital process, the most important, articulates by its
upper and inner surface, or supero-internal surface (fades or-
oitalis) with the greater wing of the sphenoid, forming part of
the outer wall of the orbit; the under surface forms part of the
temporal fossa, while the posterior margin forms part of the
sphenomaxillary fissure. The superior surface presents two
temporomalar foramina (foramen zygomatico-orbitale) , trans-
mitting temporomalar branches of the superior maxillary nerve.

It articulates with four bones. — the frontal, sphenoid, tem-
poral and superior maxilla.

Its muscular attachments are five — the masseter, temporal,
zygomaticus major and minor, and the levator labii superioris.

It is developed from one ossific center.

OSTEOLOGY.

20

The superior maxilla is the largest bone of the face,
excepting the lower jaw, and one of the most important, assist-
ing in the formation of three cavities, the mouth, nose and
orbit; two fissures, the sphenomaxillary and pterygomaxillary ;
and two fossa?, the sphenomaxillary and zygomatic. It consists
of a body and four processes — the nasal, the malar, the palatine
and the alveolar (Fig. 17).

The body (corpus maxilla) is excavated to form the maxil-
lary sinus or antrum Highmorianam (sinus maxillaris) , a large,

Incithe fotta

Posterior Dtnial CanaL

Ma.silla.ru Tultrositu.

"""»• Jiicutiad*.

Fig. 17.
Superior 'maxillary bone.

irregular triangular cavity, with its base directed inward, its
apex upward and outward, projecting into the malar process.

It- posterior wall (fades infratemporal^:) presents the 'pos-
terior dental canals, transmitting the posterior dental vessels
and nerves.

.The external or facial surface (fades anterior) (Fig. 17)
of the body presents the following points: —

Incisive fossa, or myrtiform fossa, for the origin of the
depressor alae nasi :

Canine fossa (fossa, canina) , for origin of Levator anguli
oris; • ■••*

Canine eminence, over the position of the canine tooth;

30

HUMAN ANATOMY.

Infraorbital foramen (foramen infraorbitals), for the exit
of the infraorbital nerve and artery.

The internal surface (fades nasalis) of the body presents : —

Palate process (processus palatinus) separating the mouth
from the nasal fossa?;

An irregular opening, the maxillary hiatus (hiatus maxil-
laris), leading to the antrum Highmorianum, before alluded to;

Groove completing the posterior palatine canals behind;

Hones partu&y closing 'Orrftee efAmtra-m

Inferior Twrliitatsd
■Potato

Ant. Natal Spt.

Bristle
pasted rJiToutjU
Ant. pa-lat. Canal

FIG. 18.
Superior maxillary, inner surface.

Deep groove An front, forming, with the inferior turbinated
bone and lachrymal, the lachrymal canal (canalis nasolacri-
malis) for lachrymonasal duct;

Inferior turbinated crest (crista conclialis) for the turbi-
nated bone.

The superior orbital surface (fades orbitalis) presents: —

Infraorbital groove (sulcus infraorbitaUs) about the mid-
dle for the infraorbital artery and nerve;

Anterior dental canal, one of the divisions of the infra-
orbital canal, transmitting the anterior dental vessels and nerve.

The posterior or zygomatic surface (fades infratemporalis)
presents : —

Posterior dental canals (foramina alveolaria), transmitting
posterior dental nerves and vessels;

OSTEOLOGY.

31

Maxillary tuberosity {tuber maxUlare), articulating with

the tuberosity of the palate bone;

Groo ve, converted into posterior palatine canal by the palate
bone for posterior palatine vessels and nerves.

The nasal process (processus frontalis) projects upward to
articulate with the frontal bone, its external surface smooth,
affording attachment to several muscles, its internal surface
forming part of the outer wall of the nose. It presents the
following : —

Superior turbinated crest (crista ethmoidalis) , for the
middle turbinated bone of the ethmoid;

Inferior turbinated crest (crista conchalis) below, for the
inferior turbinated bone;

Groove at the posterior margin, forming part of the lachry-
mal canal;

LacJin/ma/ tubercle, at the junction of the nasal process
with the orbital surface.

The malar process (processus zygomaticus) projects up-
ward and outward to articulate with the malar bone.

The palatine process (processus palatinus) projects from
the internal surface of the bone to form part of the roof of the
mouth and the floor of the nose. It presents: —

Anterior palatine canal or fossa (foramen incisivum),
divided into four canals ;

Foramina of Stenson, one on either side, transmit the an-
terior branch of the descending palatine artery;

Foramina of Scarpa, one in front and behind, transmit the
nasopalatine nerves;

Suture in the anterior pari showing original separation of
the incisive or intermaxillary bone (os incisivum) ;

Posterior palatine groove for the posterior palatine vessels,
and anterior palatine nerves from Meckel's ganglion;

Nasal crest (crista nasali*) for the vomer, and

Anterior nasal spine (spina nasalis anterior), projecting
from the anterior extremity of the crest.

The alveolar process (processus alveolaris) forms the
curved, spongy portion for the insertion of the upper teeth.
It presents

The alveoli or Bockets {alveoli d-entales) of varying depths,
eight in the adult, live in the child.

" articulates with nine (9) bones— the ethmoid, frontal,
lachrymal, nasal, malar, inferior turbinated, palate, vomer, and

its fellow of the opposite side.

32

HUMAN ANATOMY.

Its muscular attachments are nine — the levator labii supe-
rioris alaeque nasi, levator labii superioris proprius, levator
anguli oris, compressor naris, depressor alae nasi, orbicularis
palpebrarum, inferior obliquus, masseter and. buccinator.

It is developed from four centers : one for incisive bone, or
premaxilla ; one for palate process, or prepalatine ; one for
the maxillary portion, including the orbital and facial portion;
and one for the malar portion.

Each palate,' bone (os palatinum) is a thin, -shaped
bone, consisting of an inferior or horizontal plate and a
superior or vertical plate.

fl*J^S

0* ..-I $""L

S/iJi£/w£t?>aZ JiroeesM.

"""fty

Fig. 19.
Palate bone (viewed posteriorly).

HORIZONTAL f IAT!

Fig. 20.
Palate bone (inner surface).

Each bone assists in forming three cavities — the outer wall
and floor of the nose, the roof of the mouth and floor of the
orbit; two fossae — the pterygoid (fossa pterygoid ea) and spheno-
maxillary (fossa pterygopalatina) , and one fissure — the spheno-
maxillary (fissura oroitalis inferior).

The horizontal plate (pars liorizontalis) is quadrilateral.
Its inferior surface (fades palatina) presents

A ridge for the aponeurosis of the tensor palati muscle ;

A groove (sulcus pterygopalatinus) entering into the for-
mation of the posterior palatine canal;

Accessory palatine foramina (canal es palatini) for poste-
rior descending palatine nerves.

Its posterior border (spina nasalis posterior) presents

The posterior nasal spine (crista nasalis) for the azygos
uvulae muscles.

OSTEOLOGY. 33

The infernal border articulates with its fellow and presents

A crest for the vomer.

The vertical or perpendicular plate (.pars perpendicularis)
projects upward and inward, terminating above in two well-
marked processes — the orbital and sphenoidal processes.

The internal or nasal surface (fades nasalis) forms part
of the outer wall of the nasal fossa, and presents

An inferior turbinated crest (crista conchalis) for the in-
ferior turbinated bone;

A superior turhinated crest (crista ethmoidalis) for the
middle turbinated bone, separating the middle from the in-
ferior meatus of the nose.

The external or maxillary surface (fades maxillaris) forms
part of the sphenomaxillary i'ossa and covers part of the orifice
of the antrum.

It presents at the posterior part
• A groove, converted by the superior maxilla, into a canal,
the posterior palatine, for the passage of the descending palatine
vessels and the descending palatine branches from Meckel's gan-
glion.

The anterior border presents

The maxillary process (processus maxillaris), closing part
of the orifice of the antrum.

The pterygoid process (processus pyramidalis), or tuberos-
ity of the palate, at its lower part wedged in between the ptery-
goid plates of the sphenoid, and giving origin to part of the
superior constrictor and the internal pterygoid muscle.

Foramina of accessory descending palatine canals, for pos-
terior descending branches from Meckel's ganglion.

The obbital process (processus orbitalis), a large, hollow,
triangular process, is so called from its forming part of the
orbit.

It presents

The anterior or maxillary articular surface for superior
maxilla ;

The- posterior or sphenoidal articular surface for sphenoid;

The internal or ethmoidal articular surface, for ethmoid;

A superior or orbital surface, a smooth portion entering into
the format ion of the orbit ;

An external or zygomatic surf ace], also smooth, forming part
of the zygomatic fossa.

Tin. sphenoidal pbocess (processus sphenoidalis) is a

-mall, thin plate of hone which articulates by its upper surface
with the -phenoidal turbinated hone; its inner surface forms

:',

34

HUMAN ANATOMY.

part of the nasal fossa, and its outer surface articulates with the
pterygoid process of the sphenoid and forms part of the spheno-
maxillary fossa.

The anterior border forms a part of the sphenopalatine fora-
men, which passes between the orbital process and the sphenoidal
process.

It articulates with six (6) bones. — ethmoid, sphenoid, supe-
rior maxillary, vomer, inferior turbinated, and fellow of the
opposite side.

Its muscular attachments are azygos uvula?, tensor palati,
internal and external pterygoid and superior constrictor. It
has one ossific center at the junction of the plates.

The inferior turbinated bones (concha nasalis inferior)
are small, scroll-like bones, situated on the outer wall of the

(Inner surface.)

Fig. 21.
Inferior turbinated bones.

(Outer surface.)

nasal fossa, separating the middle from the inferior meatus.
Each presents two surfaces and three processes — the lachrymal,
ethmoidal and maxillary.

The internal surface is lined in the recent state with the
mucous membrane of the nose.

The external surface is attached to the superior maxilla and
palate bone, and presents above the three processes.

The lachrymal process (processus lacrimalis) forms part
of the lachrymal canal, articulating with the superior maxilla
and the lachrymal bone.

The ethmoidal process (processus ethmoidal is) articulates
with the hook-like process of the ethmoid bone.

The maxillary process (processus maxillaris) projects out-
ward and downward from the ethmoidal process, and narrows
the orifice of the antrum.

It articulates with four bones — ethmoid, palate, superior
maxillary and lachrymal.

Muscular attachments, none. It has one ossific center.

OSTEOLOGY.

35

The vomer is a thin, triangular plate of bone, contributing
to form part of the septum nasi. It is usually bent to one side,

The superior border presents a groove with overlapping
lamina?, or vaginal processes (alw vomeris) for articulation with
the rostrum and vaginal processes of the sphenoi I.

The inferior border articulates with the crests of the supe-
rior maxilla? and palate-bones.

The posterior border is smooth and free, forming the pos-
terior nasal septum.

The hi I end surfaces present

Furrows foT blood-vessels, and

Nasopalatine grooves for the nasopalatine nerves, which
descend to the foramina of Scarpa.

az*

It articulates with six hones — the ethmoid, sphenoid, two
palate and two superior maxilla?.

It has no muscular attachments. It is developed from a
single ossific center, although it begins as two cartilaginous
laminae, which coalesce.

The infebiob maxilla, or mandible (mandibula), is the
largesl bone in the face, it consists of a body and two rami.

The body (corpus mandibular) is the horizontal, horseshoe-
like portion, containing the lower teeth.

The external surface presents from before backward: —

Symphysis, a vertical median line indicating the junction
of the vaginal halves ;

.Mental process ( prot uberan I in mentalis), a triangular
prominence cons! ituting the chin ;

Incisive fossa, for the origin of the Levator labii inferioris;

Mental foramen (foramen mentale), for the exit of the

menial nerve and artery ;

36

HUMAN ANATOMY.

External oblique line (linea obliqua), running backward
and upward from the mental process, for the attachment of the
depressor anguli oris and depressor labii inferioris.

The internal surface presents, from before backward : —

Genial tubercles (spina? mentales), four in number, for at-
tachment of the geniohyoglossi muscles above and the genio-
hyoidei below;

Sublingual fossa (fovea sublingualis), for the sublingual
gland ;

Internal oblique line or mylohyoid ridge (linea mylo-
hyoidea), for the attachment of the superior constrictor, the
mylohyoid muscles, and the pterygomaxillary ligament;

i^v-4

Fig. 23.
Inferior maxillary bone.

Submaxillary fossa (fovea submaxillar is) , for the submax-
illary gland.

The superior or alveolar border (pars alveolaris) presents
sixteen cavities (ten in childhood) for the teeth.

The inferior border, or basilar portion (basis mandibular)
is grooved posteriorly for the facial artery.

The ramus, or perpendicular portion (rami mandibular),
on either side is somewhat quadrilateral, and presents the fol-
lowing points : —

The internal surface of ramus;

Foramen (foramen mandibulare) of inferior dental canal
(canalis mandibular), for inferior dental vessels and nerve;

Mylohyoidean groove (sulcus mylohyoideus) , described
above ;

OSTEOLOGY.

37

Spine, for attachment of the internal lateral ligament of
the lower jaw.

The upper border is surmounted by two processes, the coro-
noid and the condyloid processes, separated by the sigmoid notch.

The coronoid process (processus coronoideus) is in front,
and affords attachment for the temporal muscle.

The condyloid process (processus condyloid eus) articulates
with the glenoid fossa of the temporal bone, being supported
upon a constricted portion, the neck (collum- mandibular) , which
receives the insertion of the external pterygoid muscle, and

MIO'UVO-CLOSSUS
CtNIO-HVOIDIU*

jfyjcly'J R'fy

B a dy

Fig. 24.

Left half of inferior maxillary bone, inner surface.

presents to its outer side a tubercle for the external lateral
ligament of the lower jaw.

The sigmoid notch (incisura mandibula>) is crossed by the
masseteric vessels and nerve.

The lower border presents : —

Angle of the jaw (angulus mandibulce) , the point of junc-
tion of the ramus with the body ;

Rough surface,, for attachment of the stylomaxillary liga-
ment, and on its inner side the internal pterygoid muscle, and
on its outer side the masseter.

It articulates with the two temporal bones.

The muscular attachments are fifteen pairs; to the external
surface, sis — depressor anguli oris, depressor labii inferioris,
levator labii inferioris, orbicularis oris, platysma myoides and
buccinator; from the interna] Burface of the body, five — the

38 HUMAN ANATOMY.

geniohyoglossus, geniohyoid, mylohyoid, digastric and' superior
constrictor; and to the ramus, four — the masseter, internal and
external pterygoids and temporal.

It has two ossific centers, one for each lateral half, devel-
oped partly from membrane, partly from cartilage, being pre-
ceded in time only by one bone — the clavicle.

Changes in Lower Jaw. — Certain changes occur in the size
and shape of the lower jaw as age advances.

At birth the body is shell-like, containing sockets for the
ten temporary teeth, the mental foramen is large and opens
beneath first molar, and the coronoid process is large and at
right angles to base.

Thyrohyoid*
Slijlo-hyoid.
^Omo-hyoid,
Mylo-hyoidi
Sterno-hyoid:

Fig. 25.
The hyoid bone.

In adults the base and alveolar process are equal in size,
the mental foramen opens midway between upper and lower
borders, and the rami are at nearly right angles to base.

In advanced age the loss of the teeth and alveolar borders
greatly reduces the body, the mental foramen opens near the
alveolar border, and the rami are united at very obtuse angles
with the base.

The hyoid bone, or lingual bone (os liyoicleum) is a small,
U-shaped bone' situated at the base of the tongue, consisting of
a body ( corpus ossei hyoidei) ; two greater and two lesser cornua.

It is supported by the stylohyoid ligament from the styloid
processes of the temporal bones.

The anterior surface is divided by a crucial ridge into four
depressions for muscular attachments, and its center presents a
tubercle.

The posterior surf ace is in relation with the epiglottis, being
separated by the thyrohyoid membrane.

OSTEOLOGY. 39

The upper and hirer borders afford attachment to muscles,
and the lateral surfaces are mounted with cartilage for articula-
tion with the greater comua.

The greater comua, or thyrohyals (comua majora), pro-
ject backward, afford attachment to the hyoglossus, thyrohyoid,
and middle constrictor of the pharynx, and terminate behind
m a tubercle for the attachment of the thyrohyoid ligament.

The lesser comua, or ceratohyals (comua minora), are two
tuber-like projections attached at the junction of the body with
the greater comua, and receiving the insertion of the stylohyoid
ligaments. They do not articulate with any bone.

Its muscular attachments are ten — the Hngualis, hyoglossus,
geniohyoglossus, middle constrictor, stylo-, mylo-, genio-, sterno-
thyro-, omo- hvoid; also aponeurosis of digastric and stylo-
hyoid ligament.

Os,sific centers, five — one for body and one for each horn.

The Sutures and Fontanelles. — The sutures are divided
into three sets, those of the vertex, side, and base of the skull.

At the vertex of the skull there are three : —

Sagittal, or interparietal (sutura sagittalis) ;
Coronal, or frontoparietal (sutura coronalis) ;
Lambdoid, or occipitoparietal (sutura lambdoid ea) .

At the side of the skull are three : —

Sphenoparietal (sutwa sphenoparietalis) ;

Squamoparietal, or squamous {sutura squamosa);
Mastoparietal (sutura parietomastoidea) .

At the base of the skull are nine:—

Basilar, in center (fissura spheno-occipitalis) ,
Petro-occipital ( fissura petro-occipitalis) , ~\

Maato-oecipital | sutura occipitomastoidea) , Lon either side.
Petrosphenoidal (fissura sphenopetrosa) ,
Squamosphenoidal (sutura sphenosquamosa) , J

The sutures of the face are very numerous, but the most
important are : —

Zygomatic, at tin- temporomalar junction;

Transverse, posses from one external angular process to the other,
and connects the frontal with the malar, ethmoid, sphenoid, lachrymal,
superior maxillary and nasal bones;

intermaxillary, the median suture between the superior maxillae;

Symphysis, Hie remains of a fetal suture.

The fontanelles (fontieuli) are six membri us intervals in

the infant's skull corresponding to the four angles of the parietal
bones. The anterior or bregmatic (fontwulus frontalis), larger

40 HUMAN ANATOMY.

and lozenge-shaped, is at the junction of sagittal and coronal
sutures; the posterior (fonticulis occipitalis) , smaller and tri-
angular, is at the junction of sagittal and lambdoid sutures; and
the four lateral are at anterior and posterior inferior angles of
parietal bones (fonticulus sphenoidalis et fonticulus mastoideus) .

The Wormian, supernumerary, sutural or epactal bones
(ossa triquetra) are irregular bones interposed in intervals be-
tween the cranial bones, chiefly in the course of the lambdoid
suture.

Congenital fissures from an arrest of ossification also occur,
the most common being the parietal and sagittal fissures
(Treves).

FOSSAE OF SKULL.

The fossa? at the lateral region of the skull are temporal,
zygomatic, or infratemporal, and sphenomaxillary or pterygo-
palatine fossa.

The temporal fossa (fossa temporalis) is deeply concave in
front, convex behind ; it is formed by parts of five bones — frontal,
malar, sphenoid, temporal and parietal. It is bounded above
and behind by temporal ridge; in front by the sphenoid, malar
and frontal; below and externally by zygoma, and pterygoid
ridge on greater wing of sphenoid. It is crossed by six sutures —
sphenomalar, sphenoparietal, squamoparietal, squamosphenoidal,
coronal and transverse facial. It opens below into the zygo-
matic fossa, is filled by the temporal muscle, and lodges the deep
temporal vessels.

The zygomatic or infratemporal fossa (fossa infratem-
poralis) is an irregular cavity containing parts of temporal, ex-
ternal and internal pterygoid muscles, and is bounded above
by pterygoid ridge of sphenoid and squamous portion of tem-
poral, below by alveolar border of superior maxilla, in front
by tuberosity of superior maxillary, behind by border of ptery-
goid process, externally by zygoma and ramus of lower jaw and
internally by external pterygoid plate. It is traversed by two
fissures — sphenomaxillary and pterygomaxillary.

The sphenomaxillary fissure (fissura orbitalis inferior)
connects the zygomatic, temporal and sphenomaxillary fossa?,
and transmits the infraorbital artery, ascending branches of
Meckel's ganglion, the superior maxillary nerve and its orbital
branch.

It is bounded above by great wing of sphenoid, below by
superior maxilla and part of palate bone; internally it opens into
pterygomaxillary fissure and externally part of malar bone.

OSTEOLOGY.

41

The pterygomaxillary fissure connects the zygomatic and
sphenomaxillary fossa1, passing vertically between pterygoid
process of sphenoid and superior maxillary bone, and transmits
branches of internal maxillary artery.

The sphenomaxillary or pterygopalatine fossa (fossa ptery-
gopalatina) is a triangular cavity, bounded above by body of

Fig. 26.

1. median suture; 2, anterior palatine foramen; 3, posterior pala-
tine foranif-n: 4, posterior nasal spine; ;j, vomer; 6, hamular process;
7, pterygopalatine canal; 8, external plate; 9, scaphoid fossa; 10,
foramen ovale; 11, foramen spinosum; 12, foramen lacerum medium;
13, zygoma; 14, basilar suture; 15, gienoid fossa; 16, external audi-
tory meatus; 17, mastoid process; 18, styloid process; 1!», carotid
foramen; 20, foramen lacerum posterius; 21, occipital condyles; 2'1.
i- process; 23, foramen magnum; 24, occipital crest; 25, Inferior
curved lines.

sphenoid and orbital plate of palate-bone, within by vertical
plate of palate, in front by superior maxillary, and behind by
pterygoid process of Bphenoid. Jt lias communicating with it

42

HUMAN ANATOMY.

Three f ossse — orbital, nasal and zygomatic ;
Three fissures — sphenoidal, sphenomaxillary and pterygo-
maxillary ;

Two cavities — cranial and buccal; and

TENDS OCULI

Ant. Wdsal Spine
IneLrive fossa,.

Grew* far Taci'ai Cft

Fig. 27.
Facial portion of skull.

. Five foramina — foramen rotundum, Vidian and pterygo-
palatine posteriorly; sphenopalatine, on inner wall, and pos-
terior palatine canal, and (sometimes) accessory posterior pala-
tine canals below. It contains internal maxillary artery, superior
maxillary nerve and Meckel's ganglion.

The orbits are two pyramidal cavities, situated between
the nose and external angular processes, the forehead and face,
their bases outward and forward, their apices converging toward

OSTEOLOGY. 43

the body of the sphenoid bone. They contain the eye and its
appendages, and are each formed by seven bones — frontal, eth-
moid, sphenoid (entering into both cavities), superior maxil-
lary, lachrymal, malar and palate (separate in each). The
loof (paries superior), concave, presents: —

Externally, depression for lachrymal gland ;

Internally, depression for pulley of superior oblique;

Posteriorly, a suture between lesser wing and frontal bone.

It is formed by the orbital plate of frontal and lesser wing
of sphenoid.

The floor (paries inferior) is short and flat, and presents: —

Internally, a depression for inferior oblique muscle;

Middle, the infraorbital groove for nerve and artery;

Externally, suture of superior maxillary and malar ;

Posteriorly, suture between palate and superior maxillary.

It is formed by orbital processes of malar and superior
maxilla and orbital surface of palate.

Inner wall (paries mediaiis) presents crest of lachrymal
bone, lachrymal groove, sutures between ethmoid and sphenoid
and ethmoid and lachr}'mal.

It is formed by Lachrymal, parts of ethmoid, and sphenoid
and nasal process of superior maxilla.

The outer wall (paries lateralis) presents suture between
malar and sphenoid and orifices of malar canals. It is formed
by orbital plate of sphenoid and orbital process of malar.

The angles of the orbit are four — superior internal anil
external, inferior internal and external.

They present the following:- —

Superior internal angle:

Foramen ethmoidal anterior, transmitting anterior eth-
moidal vessels and nasal nerve;

Foramen ethmoidal posterior, transmitting posterior eth-
moidal artery ami vein;

Suture between frontal and ethmoid, and frontal and lach-
rymal ;

Superior external angle:

Sphenoidal fissure, or foramen lacerum anterius, transmit-
ting third, fourth, ophthalmic division of fifth and sixth nerves;
orbital branch of middle meningeal artery, filaments of cavern-
ous plexus of sympathetic, recurrenl branch id' lachrymal artery,
and ophthalmic vein and process of dura mater.

Su/urr between greal wing of sphenoid and malar bone,
Inferior internal angle:

44 HUMAN ANATOMY.

Suture between superior maxillary and palate bones,
uniting with lachrymal and os planum of ethmoid;

Inferior external angle:

Sphenomaxillary fissure, for passage of superior maxillary
nerve and its orbital branch, infraorbital vessels, and ascending
branches from Meckel's ganglion.

The circumference is bounded : —

Inner side by nasal process of superior maxilla and internal
angular process of frontal;

Outer side by external angular process of frontal and malar
bone;

Above {mar go supraorbitalis) by supraorbital arch;

Below {margo infraorbitalis) by lachrymal, superior max-
illa and malar.

It presents sutures malomaxillary below;

Sutures frontomalar . to outer side ;

Sutures frontomaxillary to inner side;

Supraorbital notch or foramen above, for passage of supra-
orbital nerve, artery and vein, and forms part of lachrymal
groove.

The apex presents : — •

Optic foramen, for passage of optic nerve and ophthalmic
artery.

Each orbit presents nine (9) openings, as follows: — -

1. Supraorbital foramen for passage of supraorbital artery,
vein and nerve;

2. Infraorbital canal for infraorbital nerve and artery;
'3. Anterior ethmoidal foramen for anterior ethmoidal ar-
tery, vein, and the nasal nerve;

4. Posterior ethmoidal foramen for posterior ethmoidal ar-
tery and vein;

5. M'alar foramina, for malar and temporal branches of
temporomalar nerve ;

6. Lachrymal canal, for lachrymonasal duct;

7. Sphenomaxillary fissure, for infraorbital vessels, supe-
rior maxillary nerve and its orbital branches, and ascending
branches from sphenopalatine (Meckel's) ganglion;

8. Foramen lacerum anterius (or sphenoidal fissure), for
third, fourth, ophthalmic division of fifth and sixth nerves, oph-
thalmic vein, branches of lachrymal and meningeal arteries, fila-
ments of the sympathetic nerve and a process of dura mater for
ensheathing of the nerve ;

9. Optic foramen, for optic nerve and ophthalmic artery.

OSTEOLOGY.

45

The nasal fossae (cavum nasi) consist of two large cavi-
ties separated from each other by the septum nasi (septum nasi
osseum), and opening in front by the anterior nares (apertura
piriformis), and behind into the pharynx by the posterior nares

(choanal).

They are formed by fourteen bones — the frontal, ethmoid,
sphenoid and all the bones of the face except the lower jaw
and malar.

Aoof

Ratal
Jfatal .J/iiie of Frontal But*
BcramulFUu •f£tiwtad
SjJmmJ

Prolt paticJ Amiga
HatO'ltwhrymal Co-Mat

MnmtU pmtttJi&tmjk
/itfunJtla/um ■

Ouur Wall

■fawn.!, Pre.: trfSuptfa
J.nrKrynuiL

L',uif<nmIyoa <f ditto
fnfcner I'urbxiuilcS

PalaU
Sujxru/r Hcatu*
Muidll Meat**
Inferior Keatut

floor

Anl.Xa-tal Sp

Palatr troc of Sup Man-

Palate Proc. efTalaU-

Post. Natal Spin*

int. PalaUiit Canal

Fig. 28.
Nasal meatuses.

They have each four sinuses opening into them — the eth-
moidal and antrum of Highmore (maxillary) on either side, the
sphenoidal behind and the frontal above, and communicate with
the mouth by the anterior palatine canal, with the orbit by the
lachrymal canal, with the sphenomaxillary fossa by the spheno-
palatine foramen, and with the cranium by the olfactory fo-
ramina.

They arc each hounded by an outer, inner, upper and lower

wall.

The outer wall is divided by the, middle turbinated process
of the ethmoid and the inferior turbinated bone into the superior.

middle and inferior meat uses of the uosr.

The superior meatus (meatus nasi superior), the smallest,
has three orifices opening into it: —

46 'HUMAN ANATOMY.

The posterior ethmoidal cells;

The sphenoidal sinuses, opening behind the superior tur-
binated bone and

The sphenopalatine foramen, for transmission of spheno-
palatine vessels and superior nasal and nasopalatine nerves.

The middle meatus (meatus nasi medius) has two ori-
fices : —

The infundibulum (infundibulum ethmoidal e), communi-
cating with the frontal sinuses, and through them with the an-
terior ethmoidal cells and the orifice of the antrum or maxillary
sinus.

The inferior meatus (meatus nasi inferior), the smallest,
has two orifices : —

The lachrymal canal, for lachrymonasal duct and the an-
terior palatine canals, for anterior branches of descending pala-
tine arteries (foramina of Stenson) and nasopalatine nerves
(foramina of Scarpa).

The inner wall (septum nasi) is formed by the vomer,
vertical plate of the ethmoid and the triangular cartilage of the
nose, with portions of the following bones : nasal spine of the
frontal, rostrum of the sphenoid, and the crests of the nasal,
palate and superior maxillary bones. It is grooved by the naso-
palatine and other nerves.

The upper wall or roof presents the following from before
backward : —

The nasal slit in the cribriform plate, for passage of nasal
nerve, a branch of ophthalmic ;

The olfactory foramina, for olfactory filaments and

Openings or orifices posteriorly of the sphenoidal sinuses.

The lower wall or floor presents from before backward : —

The anterior nasal spine;

The anterior palatine canals, given above ;

Crest or ridge for vomer;

Suture between superior maxillary and palate-bone and

Posterior nasal spine.

FORAMINA AT THE BASE OF THE SKULL.

Anterior fossa (fossa cranii anterior) presents one single
foramen and four in pairs : —

Foramen ccecum transmits a small vein to the superior
longitudinal sinus;

Ethmoidal fissure transmits nasal branch of ophthalmic
nerve ;

OSTEOLOGY.

47

Ant pattrftne fotJT

t* It ft Nttto-pattxt.

Transmit* Ant palat vest.
mmU* rigJttNatopalat.r

toxy palatini

Frrtxtmtta.

!Sj>It61tQL<t.prOC. of P*l*t0.

Tterygo-paUtiJi* C.

FMryTu/eal Spin* for MP- CONCTKlfA

Fig. 29.
Base of skull, external surface.

48 HUMAN anatomy.

Olfactory foramina, for filaments of olfactory bulb;

Anterior ethmoidal transmit anterior ethmoidal artery and
nasal nerve;

Posterior ethmoidal transmits posterior ethmoidal artery
and vein.

Middle fossa (fossa cranii media) presents nine (9)
pairs : —

Optic foramen transmits the optic nerve and ophthalmic
artery ;

Foramen lacerum anterius, or sphenoidal fissure (fissura
orbitalis superior), transmits third, fourth, three branches of
the ophthalmic division of the fifth and the sixth nerve, orbital
branch of the middle meningeal, recurrent branch from the
lachrymal arter}^, filaments of the sympathetic nerve, and
ophthalmic vein;

Foramen rotundum transmits second division of fifth or
superior maxillary ;

Foramen Vesalii transmits a small vein;

Foramen ovale transmits third division of fifth or inferior
maxillary nerve, small petrosal nerve and small meningeal
artery ;

Foramen spinosum transmits middle or great meningeal
artery ;

Foramen lacerum medium transmits the internal carotid
artery, carotid plexus, a branch of ascending pharyngeal artery
and the Vidian or large petrosal nerve;

Foramen for lesser petrosal nerve, and

Hiatus Fallopii transmits petrosal branch of middle menin-
geal artery and petrosal branch of the Vidian nerve.

Posterior fossa (fossa cranii posterior) presents six pairs
and one single one :—

Meatus auditorius intemus transmits auditory artery, facial
and auditory nerves;

Aquceductus vestibuli transmits small artery and vein and
lodges a process of dura mater ;

Foramen lacerum posterius, or jugular foramen, transmits
inferior petrosal sinus and lateral sinus, forming the internal
jugular vein, glossopharyngeal, pneumogastric, spinal accessory
nerves and meningeal branches of ascending pharyngeal and
occipital arteries;

Mastoid foramen transmits small vein to the lateral sinus
and small artery from occipital to the dura mater;

Anterior condyloid foramen transmits meningeal branch
from ascending pharyngeal artery and hypoglossal nerve ;

OSTEOLOGY.

49

Viprtl

Creevt fr* Super l-iaituj.fftmtt
Oromtfar AlOsr. M.rSnytalA
F'mmtn Cxtur*-
Crista- CniU
m Slit ft

Anterior Xthmoidnl £,
Or if lets for ^factory ne
Fom+xtxov Edimoldal Ft

Ethmoidal Spins

Olfactory Cr,

Ofti* Foramen

Opt Co Qtqov*. — . t^

OL

Aftter/or Clirwid proa.

KiJJU CUnoi'J j? rev

Fotterior Cliwrid proa

Greov* f** 6* «+n>m

Far- Lirrrurti medium

Crifiot of Carried Canal

<wi t?r Catterum Gavalcon

Mtafut Auditor. Interim*

Slit for DuT*-M*t*r

Sup. FttTosttl yrvorv

Fit. loeerum paattruu

Anterior Condyloid Ton

Aqurduoe. VetttbmU

Voct+rior Condyloid Fom

Meutotd Fox

JjMt. JKsnlnqsal GrewiM.

Ida. 30.

Floor of the cranium.

50 HUMAN ANATOMY.

Posterior condyloid foramen transmits posterior condyloid
vein;

Foramen magnum transmits vertebral arteries, medulla ob-
longata and its membranes and the spinal accessory nerves.

OTHER FORAMINA OF SKULL.

The external surface of the base, or basilar surface, pre-
sents seven pairs : —

Palatal portion: —

Incisive foramina transmit nerves and vessels to the incisor
teeth ;

Foramina of Stenson transmit the anterior branch of the
posterior palatine vessels;

Foramina of Scarpa transmit the right and left nasopala-
tine nerve;

Posterior palatine foramina transmit posterior palatine ves-
sels and descending palatine nerve;

Accessory palatine foramina transmit posterior palatine
nerves ;

Pterygopalatine canals transmit pterygopalatine vessels,
and the

Pterygoid or Vidian canal (canalis pterygoideus) transmits
the Vidian artery and nerve.

Lateral portion presents nine pairs : —

Opening of the Eustachian tube;

Opening of the tensor tympani canal transmits the tensor
tympani muscle;

Glaserian fissure transmits the tympanic branch of the in-
ternal maxillary artery and lodges the processus gracilis of the
malleus ;

Canal of Huguier transmits chorda tympani nerve;

Foramen for Jacobsons nerve, the tympanic branch of the
glossopharyngeal nerve ;

Foramen for Arnold's nerve, the auricular branch of the
pneumogastric nerve ;

Opening of aquaductus cochlea transmits a vein from the
cochlea to internal jugular vein;

Auricular fissure gives exit to Arnold's nerve;

Stylomastoid foramen transmits the facial nerve and stylo-
mastoid artery.

Anterior region presents three pairs: —

Supraorbital foramen, or notch, transmits supraorbital ar-
tery, vein and nerve;

OSTEOLOGY.

51

Fie 31.
8t< rnum and costal <artilages.

52 HUMAN ANATOMY.

Infraorbital foramen transmits infraorbital artery and
nerve, and

Mental foramen transmits mental nerve and artery.

BONES OF THE TRUNK.

The sternum, or breast bone, is a long, narrow, sword-like
bone occupying the anterior part of the thorax and consisting
of three portions: manubrium (manubrium sterni or pre-
sternum— handle), gladiolus (mesosternum or corpus sterni —
blade), xyphoid or ensiform appendix (processus xiphoideus or
metasternum — point). Its anterior surface is irregularly flat,
posterior surface slightly concave.

Manubrium sterni (presternum) is thick and triangular,
and presents above the interclavicular notch, on either side of
which are facets for articulation of clavicles. Laterally it pre-
sents an articular facet for the cartilage of the first rib and a
half facet for part of second costal cartilage.

Gladiolus or corpus sterni (mesosternum) is the longest,
narrowest portion and presents about its center, between the
third and fourth segments, the sternal foramen, laterally facets
for half of the second and for the third, fourth, fifth and sixth
costal cartilages.

Ensiform appendix (processus xiphoideus or metasternum)
is cartilaginous in youth and varies much in size and shape.

It articulates with the clavicles and seven costal cartilages
on side.

Its ossiflc centers are six — one each for the manubrium and
appendix and four for the gladiolus, or body.

Its muscular attachments are ten— sternomastoid, sterno-
hyoid, sternothyroid, pectoralis major, triangularis sterni, ob-
liquus externus and interims, transversalis, rectus and dia-
phragm.

The ribs (costce), twelve on each side, form a series of nar-
row elastic arches on each side of the thorax, constituting the
chief part of the thorax. They are divided into seven vertebro-
sternal, true or sternal ribs (costce vera.), each of which joins the
sternum by a separate costal cartilage; three vertebrochondral,
or false (costm spurice), the cartilages of which join each other
and with the seventh before uniting with the sternum, and two
vertebral, free or floating, which have no sternal attachment.

Each rib consists of a head, neck, tubercle and body.

The head (capitulum costm) presents facet (except the first,
tenth, eleventh and twelfth) for articulation with the bodies of

OSTEOLOGY.

53

the contiguous dorsal vertebra1,, separated by a ridge (crista
capituli) for the interartienlar ligament.

The neck (collum costce) or constricted portion is smooth
in front and presents a rough surface behind for the middle cos-
totransverse ligament and a rough crest (crista colli costce)
above for the anterior costotransverse ligament.

Sfifjttfy

Sinjh urttcular faett —

SinyU »rtit. /Lett —

Jinglt artit. fae.

Fig. 32.
The peculiar ribs.

The tubercle or tuberosity (tuberculum costce) (wanting in
eleventh and twelfth), presents an articular surface (fades art ic-
ularis tuberculi) for articulation with the transverse process of
the vertebra below, and a non-articular surface foT attachment
of the posterior costotransverse ligament.

54 HUMAN ANATOMY.

The shaft or body (corpus costce) is flat, thin and twisted
on itself. Its anterior extremity presents an oval depression for
costal cartilage.

The internal surface is smooth, concave, and presents in
front of the angle a ridge, forming the side of the groove on the
inferior border.

The external surface is rough, convex and presents a little
in front of the tubercle, a bend or angle (angulus costce) marked
by a prominent line, and near the sternal extremity another
bend, the anterior angle, marked by an oblique line.

The superior border^ is round and thick and presents an
external and internal lip for external and internal intercostal
muscles.

The inferior border, at its posterior third, presents a groove
(sulcus costai) for the intercostal vessels and nerve, and at its
anterior two-thirds is sharp and thin.

Peculiar Ribs. — The peculiar ribs are the first, second,
tenth, eleventh and twelfth.

The first is short, broad, has no angle, and but one facet
on the head. Its upper surface is marked by two parallel
grooves, the anterior for the subclavian vein, the posterior for
the artery separated by a tubercle (tubercidum scaleni) for in-
sertion of scalenus anticus muscle, — an important guide in liga-
tion of the subclavian artery.

The second resembles the first in being flattened and not
twisted. The tubercle and angle are slight and almost coincide
in position. The outer surface of the shaft presents near its
middle a rough eminence for the second and third portions of the
serratus magnus.

The tenth rib has but one facet for articulation with the
tenth dorsal vertebra.

The eleventh has single facet on head, slight angle, but no
tubercle or neck.

The twelfth, single facet, but no angle, tubercle, or neck.

The ribs articulate with twelve vertebrae behind and twelve
costal cartilages in front.

Muscular attachments are twenty — scalenus anticus, medius
and posticus, pectoralis minor, intercostals, serratus magnus, ob-
liquus externus, transversalis, quadratus lumborum, diaphragm,
latissimus dorsi, serratus posticus, superior and inferior; sacro-
lumbalis, musculus accessorius ad iliocostaleni, levatores costa-
rum, longissimus dorsi, cervicalis ascendens, and infracostales.

Each rib has one center for its head, shaft and tubercle,
except the eleventh and twelfth, which have but two centers,
that for the tubercle being wanting.

OSTEOLOGY.

55

O

c

2-

•3

Fio. 33.
The vertebral column, or spine.

56

HUMAN ANATOMY.

VERTEBRA.

The spine, or vertebral column (columna vertebralis) ,
is a flexible column composed of twenty-six bones ( thirty- three
vertebrae), as follows: seven cervical, twelve dorsal, five lumbar,
sacrum and coccyx. Each vertebra consists of a body or cen-
trum (corpus vertebrae), and an arch (arcus vertebra), com-
posed of two pedicles and two laminae, supporting seven processes
— one spinous, two transverse and four articular.

The body (centrum — corpus vertebra), the large, solid,
anterior portion, is generally half-cylindrical, concave behind,
convex in front and sides. Its upper and lower surfaces are

ffiuftrui? Artie, true,

Demi .facet tor /lead of Rib

Taeet^r Tuhnh of Sib

Demijacetfir7ua.il of Rih
Infer. Artie. Proe*

Fig. 34.
A dorsal vertebra.

broad and rough, for attachment of interarticular cartilages.
Its posterior surface has large foramen for exit of veins.

The pedicles (radix arcus vertebra) project backward (ex-
cept the cervical, which project obliquely outward), and present
four intervertebral notches (incisura vertebralis superior et in-
ferior), two each, above and below. These, when articulated,
form interarticular foramina (foramina intervertebral) for
exit of spinal nerves and passage of blood-vessels.

The lamina are two broad, flat plates of bone, projecting
backward and inward from the pedicles to complete the verte-
bral arch and inclose the spinal foramen. Their upper and
lower margins are rough for attachment of the ligamenta sub-
flava.

The spinous processes vary much in size and shape in the
different regions. .They project backward from the junction
of the laminae and afford attachment for muscles.

OSTEOLOGY.

57

The transverse processes (processus transversi) project one
on each side, from the junction of the laminae with the pedicles.
•and in the cervical region from the sides of the body also, in-
closing the foramen for the vertebral artery.

AiiUritrTubircli of TraniTrtc.

lorami* f„ Virttbrtl Art *.

fortrirrTulcrtlt *f TrantPi

rdiavertc JPtvc/sa

JUP/fiOT- Articular PmH&
nfcrwrAlticular SractO

Fig. 35.
A cervical vertebra.

The articular processes (zygapophyses) , four in number,
project one above and below on each side, from the junction of
the lamina and pedicles. The two superior (processus articu-
lar /'.-■ superior) project upward and more or less backward, the

Tuberc/f

Trani.Proc,

J" or am -a /or
Vertebral ArtX

'ovefer Vert of. Art J
and 1" Cerv.Norva

inferior (processus arlicu/aris inferior) downward and more or
lese forward, articulating with the corresponding processes of
the adjoining vertebra.

The Bpinal foramen (foramen vertebrate) is a large, tri-
angular canal, inclosed by the body in front, the pedicles later
ally and the lamina' behind, f<»r the passage of the spinal cord
and it- membranes.

58 HUMAN ANATOMY.

The ceevical vertebra (vertebrce cervicales) are char-
acterized by small body, concave above, convex below, the an-
terior margin overlapping the one below; short and bifid trans-
verse process, perforated at base by foramen for vertebral artery :

Artie. Surf.firJUU*

Gb&tfove,

Treni.frcf

Fig. 37.
The axis.

oblique articular processes — superior convex directed upward and
backward, inferior concave downward and forward; short spin-
ous process, bifid, placed horizontally; long and narrow lamina,
inclosing large, triangular spinal canal (canalis vertebralis) .

Fig. 38.
Seventh cervical, or vertebra prominens.

The peculiar cervical vertebrce are first, second and seventh.

The first or atlas is ring-like, without either body or spinous
process, and consists of an anterior arch (arcus anterior), a
posterior arch (arcus posterior) and two lateral masses (massce
laterales). The anterior arch, convex in front, presents tubercle
for longus colli muscles and behind articulates with odontoid

OSTEOLOGY.

59

process of axis. The ggstejioT arch is deeply grooved above for

transmission of vertebral artery and suboccipital nerves and
terminates behind in a rudimentary spine. It articulates above
with condyles of occipital, below with axis. The transverse
process is short and contains a foramen.

The axis (epistropheus), so called from the pivot-like odon-
toid process (dens), which projects from the upper part of its
hodv to articulate with the anterior arch and transverse ligament
of atlas.

*nnr*/tu*t
"fir Artie fm.

Fig. 39.
Peculiar dorsal vertebrae.

The seventh resembles the dorsal series; its spinous process
being long, not bifid, and prominent; bence its name, "vertebra
|.roiiiiii<-ii-.'" To ii is attached die ligamentum nucha1.

Tin: i)oi;s.\i> vi:i;ti;i:i;.i-; (vertebra thoracales) have large,
lie;irt-.dia|icd bodies, Hat above and below. Laterally have demi-
articular facets (fovea costalis superior et inferior) for heads
of ribs; long, strong, transverse processes, marked by Facel for
tubercle of rib (fovea costalis vertebralis) ; vertical articular
processes, superior backward, inferior forward; long, triangular,
overlapping spinous proems; small, and nearly circular, spinal
canal.

60

HUMAN ANATOMY.

The peculiar dorsal vertebra? are : first, which resembles
cervical, and has distinct facet for head of first rib, and half-
one for half of second head; tenth, eleventh and twelfth; one
facet for head of rib; and eleventh and twelfth, no facet on
transverse processes for tubercle of rib.

The lumbar vertebra (vertebra? lumbales) are the
largest, and have transverse oval body, flat above and below;
long, thin, transverse processes, representing ribs; vertical proc-
esses interlocking with adjacent vertebrae; large, triangular
spinal canal.

The last lumbar is peculiar in having body thicker in front,
shorter and stronger transverse process, and inferior articular
processes wider apart, and directed forward.

Super. Artie. Proc.

Fig. 40.
A lumbar vertebra.

Muscular attachments to atlas, ten — rectus anticus minor,
rectus lateralis, rectus posticus minor, obliquus superior and
inferior, splenius colli, levator anguli scapulas, interspinous and
intertransverse. To axis, ten — the last five of preceding, and
obliquus inferior, rectus posticus major, semispinalis colli, mul-
tifidus spinas, scalenus posticus and transversalis colli.

To the remaining vertebras are attached anteriorly ten (10)
muscles, and posteriorly twenty- two (22) [vide Spinal Muscles,
p. 107].

Development. — The ossific centers for each vertebra are
three primary, one for the body and one for each side, and five
secondary epiphyses, as follows : one for tip of each spinous and
transverse process, and the remaining two are thin plates, on
articular surfaces.

The exceptions to this rule are : atlas, with two primary
centers and one epiphysis ; the axis, with three extra centers for

OSTEOLOGY.

61

odontoid process; the seventh cervical, with one extra center for
each transverse process, and the lumhar vertebras, two additional
centers for tubercles.

The sackum (os sacrum) is a large, wedge-shaped bone,
base above, apex below, with expanded lateral masses and alse,
composed of five consolidated sacral vertebra?, and forming the
posterior wall of pelvis.

The base (basis oss. sacri) articulates with the last lumbar
vertebra. Its anterior edge forms the promontory or sdcrover-

FromontoTy

Fig. 41.
The sacrum, anterior surface.

tebral angle (promontoriam) on each side of which is a smooth
triangular surface, the ala (ala sacral is). Behind the artic-
ulating surface is the sacral canal (canalis sacfaUs), ami on
either side are the superior processes.

The apex (apex oss. sacri) is small and articulates with the
coccyx.

The anterior concave surface (fades pelvina) presents four
ridges (lineaz transversa;) indicating the original separations,
which terminate externally in eight anterior sacral foramina

(foramina SOCralia anlcrinra ) . with wide, shallow i/ronrcs, for
the exit of the anterior sacral nerves. To the outer side of these
foramina i- the lateral mass (pars lateralis) for origin of pyri-
formifl muscle.

62

HUMAN ANATOMY.

The posterior surface (fades dor sails) presents rudimen-
tary spinous articular and. transverse processes, the lamina? of
the last two segments being deficient.1 On the other side of the
spinous process is a broad, shallow concavity, the sacral groove,
for the origin of the erector spinse muscle, and external to the
articular processes are four posterior sacral foramina (foramina
sacralia posteriora) for the exit of posterior sacral nerves.

The lateral surfaces have each a rough articular surface for
articulation, with ossa innominata, and below presents a deep

Pig. 42.
The sacrum, posterior surface.

notch on each side of the apex, which is converted by articulation
with the transverse process of the coccyx into the fifth sacral
foramen, for exit of anterior division of the fifth sacral nerve.

The sacral canal (canalis sacralis), continuous above with
the spinal foramen of. the vertebrae, runs through the center.
Large and triangular above, small and flattened below, its lower
posterior wall is deficient (hiatus sacralis). It lodges the sacral
nerves, and out of it pass the anterior and posterior sacral
foramina.

i The articular processes of the fourth and fifth unite to form the
sacral cornua for articulation with the cornua of the coccyx.

OSTEOLOGY. (53

It articulates with four bones, — two os,sa innominata, last
lumbar vertebra and coccyx.

Muscular attachments are seven — iliacus, piriformis, coc-
cygeus, gluteus niaximus, latissimus dorsi, multifidus spinae and
erector spina?.

Its ossific centers are thirty-five, as follows: bodies, includ-
ing interarticular plates, three each (15) ; arches, two each (10) ;
lateral masses, six (6) ; epiphyseal plates of lateral surfaces,
four (1). Total, 35.

The coccyx (os coccygis) is a small' triangular bone, re-
sembling a cuckoo's beak, and composed of four rudimentary
vertebra? more or less co-ossified (vertebra coccygece).

•The base articulates with the sacral apex, being prolonged
upward into two cornua to complete the fifth posterior sacral
foramen for exit of posterior Branch of fifth sacral nerve.

Laterally the base is prolonged into rudimentary transverse
processes, completing with the notch of the sacrum the fifth
anterior sacral foramina for exit of the anterior branch of fifth
sacral nerve.

The anterior concave surface supports the rectum and gives
attachment to levator ani muscle and anterior sacrococcygeal
ligament.

The posterior convex surface presents rudimentary, artic-
ular processes and transverse grooves.

The apex is roimded, occasionally bifid, or deviated to one
side, and affords attachment to the levator ani and sphincter
ani muscles.

The muscular attachments are coccygei, gluteus maximus,
extensor coccygeus (occasionally present), levator and sphincter
ani.

Its ossific centers are four — one for each segment.

THE UPPER EXTREMITY.

The upper extremity consists of the arm, forearm and
hand. It is attached to the trunk by the shoulder-girdle formed
by the clavicles, and scapulae and contains the following bones:
Clavicle, scapula, humerus, radius, ulna, eight carpus, five meta-
carpus and fourteen phalanges.

Tin: CLAVICLE (clavicula) , or collar- or key- bone, is a long
bone, curved horizontally like the italic letter /, extending almost
horizontally between the sternum and acromial process of scap-
ula. Its inner two-thirds are cylindrical and convex in front, its
outer third flattened from above downward and concave in front.

64 HUMAN ANATOMY.

It consists of a body, or shaft, and outer, or acromial, and
inner, or sternal extremities.

The shaft presents in its outer third the following points : —

Superior surface, rough impression in front for deltoid mus-
cle, rough impression behind for trapezius;

Anterior border, occasionally deltoid tubercle about the
center for attachment of deltoid;

Inferior surface, conoid tubercle (tuberositas coracoidea)
at the posterior border for conoid ligament; oblique line ex-
tending outward and forward from this for attachment of
trapezoid ligament.

The inner two-thirds is prismatic and presents three sur-
faces and three borders: —

AeraLiiulUxtV

Si 'e mih t Ej.-tr

FIG. 43.
The left clavicle, upper surface.

Anterior surface, divided by line into upper rough surface
for sternomastoid muscle and lower for pectoralis major;

Posterior or cervical surface gives attachment to sterno-
hyoid muscle and presents foramen (foramen nutricium) for
nutrient artery.

Inferior or subclavian surface presents : —

Facet, continuous with sternal articular surface, for car-
tilage of first rib ;

Rhomboid impression (tuberositas costalis) for costoclavic-
ular or rhomboid ligament;

Subclavian groove for attachment of subclavian muscle;

Longitudinal line, frequently dividing the groove into two
parts, for intermuscular septum of the muscle.

Anterior border separates the anterior and posterior sur-
faces and limits the attachment of the pectoralis major.

Superior border gives attachment to the sternomastoid
muscle.

Posterior or subclavian border is short and concave, extend-
ing from the rhomboid impression to the conoid tubercle and
giving attachment to the subclavian fascia.

OSTEOLOGY.

65

The acromial extremity {ex/ rem Has acromialis) presents an
oval facet (fades articularis acromialis) for articulation with
the acromial process of the scapula and a rough circumference
for acromioclavicular ligaments.

The sternal extremity (extremitas sternalis) is triangular,
and presents a facet (fades articulans sternalis) for cartilage
of sternal articulation and rough circumference for sternoclavic-
vdar ligaments.

The clavicle articulates with three hones — the sternum,
scapula, and first costal cartilage.

The muscular attachments are seven — subclavius, platysma,
sternohyoid, sternomastoid, trapezius, pectoralis major and del-
toid.

Fig. 44.
The left clavicle, under surface.

end.

Its ossific centers are two — one each for bodv and sternal

The scapula, or shoulder Hade, is a large, flat, triangular
bone situated on the upper posterolateral aspect of the thorax
from the second to seventh rib, inclusive.

It consists of a body, head, neck, acromion and coracoid
processes, and presents two surfaces, three borders, and three
angles.

The anterior surface, venter or costal surface (fades cos-
tal is) presents: —

Subscapular fossa (fossa subscapularis) , a concave tri-
angular surface for attachment of subscapular muscles,
marked by

Oblique ridges (linen' musculares) for the tendinous inter-
sections of the muscle ;

Marginal warfare, for attachment of serratus magnus;

Subscapular angle (angvlus subscapularis) , a transverse
depression at the upper pari for the thickest pari <>r the muscle.

The posterior surface, or dorsum (fades dorsalis),
presents : —

5

66

HUMAN ANATOMY.

Spine (spina scapulae), a bony ridge passing upward, for-
ward, and outward, dividing it unequally into two fossae, afford-
ing attachment to the trapezius muscle above and the deltoid
below, and terminating above in the acromion process;

Supraspinous fossa (fossa supraspinata) above the spine,
for the origin of the supraspinatus muscle;

Infraspinous fossa (fossa infraspinata) below, for the
origin of the infraspinatus muscle;

Fig. 45.
The scapula, anterior surface.

Nutrient foramen, near the upper part of the infraspinous
fossa, for nutrient artery.

The marginal surface extends from the glenoid cavity down-
ward and backward to an inch above inferior angle, its inner
side formed by

An elevated ridge, for the attachment of the aponeurosis
between the infraspinatus and two teres muscles; its outer side

OSTEOLOGY.

67

by the axillary border. It is divided by an oblique line into two
parts, the upper for the teres minor and the lower for the teres
major muscles, and crossed by a groove near the upper part for
the dorsalis scapulas vessels;

>*'/

Co r a cot' &

Fir,. 46.
The scapula, posterior surface.

A smooth, triangular surface at the root <>f the spine over

which the trapezius glides.

The superior border (marf/o superior), shortest, presents: —
Suprascapular ootch (incisura scapula') at the base of the

coracoid process, converted into a foramen [suprascapular] by

the transverse ligament, for the passage of the suprascapular

nerve ( the artery passing above) ;

08 HUMAN ANATOMY.

Origin of omohyoid muscle from this border just internal
to notch.

External or axillary border (mar go axillaris), thickest,
presents : —

Eough impression, the infraglenoid tubercle (tuberositas
infraglenoidalis), just below glenoid cavity, for origin of long
head of triceps muscle, and below

Longitudinal groove, for origin of part of subscapulars.

Internal, veretebral border — base (mar go vertebralis) , long-
est, presents : —

Anterior lip, for insertion of serratus magnus;

Posterior lip, for attachment above of supraspinatus, below
infraspinatus.

•The superior angle (angulus medialis) gives attachment to
part of levator anguli scapulas;

The inferior angle (angulus inferior), for attachment of
teres major, and sometimes part of latissimus dorsi.

The anterior or external angle (angulus lateralis) is thick-
est, and forms the head.

The head is connected to the body of the scapula by a con-
stricted portion, the neck (collum scapulae), from the anterior
surface of which arises the coracoid process. It presents

The glenoid cavity or fossa (cavitas glenoidalis) , a shallow,
pyriform, articular depression, deepened in the recent state by
the glenoid ligament, for the head of the humerus. To its upper
part or apex is attached the long head of the biceps muscle.

The acromion process (acromion), forming the summit
of the shoulder, is a triangular process, projecting forward, out-
ward and upward, to overarch the glenoid cavity. It gives at-
tachment by its upper surface to the platysma and deltoid and
by its inner margin to the trapezius. It presents

An apex, for attachment of coracoacromial ligament;

Articular facet, just behind the apex for the clavicle.

The coracoid process (processus coracoideus) — like a
crow's beak — arches forward, upward, and inward above the
glenoid cavity. It presents

Attachment for pectoralis minor muscle from the anterior
border near the tip;

Apex, for attachment of coracobrachialis and short head of
biceps ;

Rough impression at the inner side of the root for the
conoid ligament, and from it

A ridge running outward and forward for the trapezoid
ligament.

OSTEOLOGY.

69

r--.a

FIQ. 47.

The humerus, anterior
surface.

Fig. 48.

The humerus, posterior
surface.

70 HUMAN ANATOMY.

It articulates with the clavicle and humerus.

Its muscular attachments are 18 : platysma, supra- and
infra- spinatus, subscapular, deltoid, trapezius, omohyoid, ser-
ratus magnus, levator anguli scapulge, rhomboideus major and
minor, triceps, teres major and minor, biceps, coracobrachialis,
pectoralis minor and latissimus dorsi.

Its ossific centers are seven — one each for body, posterior
border, and inferior angle, and two each for acromion and cora-
coid processes.

The humerus, or arm bone, the largest and longest bone
of the upper extremity, consists of a shaft, head, neck, greater
and lesser tuberosities and lower extremity.

The shaft (corpus humeri), cylindrical above, flattened and
prismoid below, becomes twisted in the middle, and presents

A rough triangular surface about the middle of its outer
surface (tuberositas deltoidea) for insertion of the deltoid
muscle, and a

Musculo spiral groove for the musculospiral nerve and supe-
rior profunda artery, on each side of which arise the external and
internal heads of the triceps muscle.

The upper extremity presents

The head (caput humeri) forming nearly a sphere, project-
ing upward, backward and inward, articulating with the glenoid
cavity ;

The anatomical neck (collum anatomicum) , immediately
beneath, is slightly grooved for the attachment of the capsular
ligament ;

Greater tuberosity (tuherculum ma-jus), external to the
head and lesser tuberosity, with three facets from before back-
ward for attachment of supraspinatus, infraspinatus and teres
minor muscles;

Lesser tuberosity (tuherculum minus), smaller but more
prominent than greater, is anterior to head, for the subscajmlar
muscle ;

Bicipital groove (sulcus intertubercularis) , passes down-
ward and inward between the two tuberosities and lodges the
long tendon of biceps;

The anterior bicipital ridge (crista tuberculi minoris),
bounds the groove in front and receives insertion of pectoralis
major muscle;

The posterior bicipital ridge (crista tuberculi majoris), re-
ceives the latissimus dorsi and teres major;

The surgical neck (collum chirurgicum) , including the
head, neck and both tuberosities;

OSTEOLOGY. 71

A rough impression near the center of the inner border for
the coracobrachial muscle ;

Nutrient canal, below and directed toward the lower ex-
tremity.

The lower extremity presents from within outward the fol-
lowing1 : —

Internal condyloid ridge, extending upward from the con-
dyle ;

Internal condyle or epicondyle (epicondylus medialis),
more prominent than external, gives origin to the flexors and
pronator radii teres;

EpitrocMea, an eminence separating the trochlea from the
internal condyle;

Trochlea {trochlea humeri) a pulley-like articulating sur-
face for greater sigmoid cavity of ulna;

Coronoid fossa (fossa coronoidea) a small depression bound-
ing the trochlea in front, and receiving the coronoid of the ulna
in flexion ;

Olecranon fossa (fossa olecrani), a larger depression behind,
and receiving the olecranon process of ulna in extension;

Supratrochlear foramen, sometimes formed by perforation
of one fossa into the other;

Radial head, or eapitellum (capitulum humeri), a smooth,
rounded eminence articulating with cup-like depression on head
of radius :

External condyle or epicondyle (epicondylitis lateralis), less
prominent, gives origin to the extensors and supinators;

External condyloid ridge, extending upward on the shaft
from the condyle.

It articulates with three bones — scapula, radius and ulna.
Its muscular attachments are twenty-five — subscapulars,
supra- and infra- spinatus, teres major and minor, pectoralis
major, latis&imns dorsi, deltoid, coraeobrachialis, brachialis an-
ticus, triceps, pronators and flexors to inner condyle, pronator
radii teres., flexor carpi radialis, palmaris Longus, flexor sublimus
digitorum, flexor carpi ulnaris, supinators and extensors to outer
condyle, supinator Longus, extensor' carpi radialis longior and
brevior, extensor communis digitorum, extensor minimi digiti.

i Some confusion exists in anatomical works because of the loose.
employment of the terms condyle, epicondyle, ami epitrochlear. tt
should lie borne in mind, however, thai many anatomists use Hie terms
external condyle and external epicondyle synonymously, while others
designate the inner condyle ;i- the internal epicondyle or epitrochlea.

72 HUMAN ANATOMY.

extensor carpi ulnaris, anconeus and subanconeus, supinator
brevis.

Its ossific centers are seven — one each for head, shaft, tu-
berosities, condyles, radial head, and trochlear portion.

The ulna, or elbow bone, is a long bone to the inner side
of the forearm, and consists of a shaft and an upper and lower
extremity. It forms the greater part of the articulation with the
humerus, but does not enter into the formation of the wrist-
joint, being excluded by the interarticular fibrocartilage.

The shaft (corpus ulnce) is prismatic above, smooth and
rounded below, and presents : —

Anterior or palmar surface (fades volaris), gives attach-
ment to the deep flexors and pronator quadratus;

Nutrient foramen (foramen nutricium) on anterior sur-
face, directed upward toward the elbow-joint;

Posterior or dorsal surface (faeies dorsalis) marked above
by an oblique line for part of supinator brevis, above which is
smooth triangular surface for anconeus muscle, and the lower
third for extensor muscles of the thumb;

External or interosseous border (crista inter ossea) , sharp
in middle two-thirds, for attachment of interosseus membrane.

The upper extremity is large and irregular, and presents : —

Olecranon process (olecranon — head of elbow), projects
upward and forward, its apex being received into the olecranon
fossa of the humerus in extension of the forearm; its upper
border has rough impression for the triceps muscle; its lateral
borders are grooved for external and internal lateral ligaments;

Coronoid process (processus coronoicleus) , smaller than
olecranon, projects forward from anterior surface, being re-
ceived into coronoid fossa of humerus in flexion.

Its upper surface forms part of the great sigmoid cavity.

Its under surface has rough impression for insertion of
brachialis anticus, and has, at its junction with the shaft, the
tubercle of the ulna (tuberositas ulnce) for the oblique ligament.

Its outer surface is the lesser sigmoid cavity.

Its inner surface gives> attachment to the internal lateral
ligament, and the flexor digitorum sublimis, flexor profundus
digitorum, and one head of pronator radii teres.

Greater sigmoid cavity (incisura semilunaris) is a large,
semilunar depression between the olecranon and coronoid proc-
esses, divided into two unequal lateral parts by an elevated
ridge. It is continuous on the outer side with the lesser sig-
moid cavity and articulates with the trochlear surface of the
humerus.

OSTEOLOGY.

73

tICTdJI DICITORU
1UBLIMII

ccrnrioiutZ orig.

Styloid freer u

Stylotd£rct4St

Fig. 49.
Ulna and radius, anterior aspect.

74 HUMAN ANATOMY.

Lesser sigmoid cavity (incisura radialis) is an oval, con-
cave, articular depression, external to the coronoid process, for
articulation with the head of the radius. Its prominent ex-
tremities give attachment to the orbicular ligament.

The lower extremity is small and cylindrical and presents : —

Head (capitulum ulnce), an external, rounded, articular
process, for the triangular flbrocartilage below and the sigmoid
cavity of the radius externally ;

Styloid process {processus styloideus) projects from the
posterior and internal part of the extremity, its apex gives at-
tachment to the internal lateral ligament of the wrist, and it is
marked at its root by a depression between it and the head, for
attachment of the fibrocartilage ;

Groove, upon the posterior surface, for passage of extensor
carpi ulnaris.

It articulates with two bones — humerus and radius.

Its muscular attachments are sixteen — brachialis anticus,
triceps, anconeus, flexor and extensor carpi ulnaris, pronator
radii teres, flexor sublimus and profundus digitorum, pronator
quadratus, supinator breyis, extensor indicis, extensor ossis
metacarpi, extensor secundi internodii pollicis and flexor longus
pollicis.

Its ossific centers are three — one each for shaft, olecranon
and inferior extremity.

The radius is a long bone, shorter than the ulna, situated
on the outer side of the forearm, the upper end small, the shaft
slightly curved, and the lower end expanded to form part of the
wrist joint. It consists of shaft, upper and lower extremity.

The shaft (corpus radii) is prismoid, slightly curved, and
presents

An internal or interosseous border (crista interossea) ,
sharp and prominent, for. interosseous membrane;

An anterior or palmar border (mar go volaris) marked at
its upper third by an oblique line, for attachment of flexor
longus pollicis, supinator brevis and flexor sublimis digitorum;

Anterior, palmar, or flexor surface (fades volaris), affords
attachment above for flexor longus pollicis, below for pronator
quadratus, and presents at the junction of middle and upper
two-thirds a nutrient foramen directed upward;

Posterior, dorsal, or extensor surface (fades dorsalis) gives
attachment at upper third to supinator brevis, and at middle
third to extensors of thumb.

The upper extremity presents: —

OSTEOLOGY.

75

ft* 1XT. CAJIPI IAD.

l/T.CMH KAO
1ST. tUUMM MTtftN

J|£: '.""«

Bto. 50.

Radius and ulna, posterior aspect.

76 HUMAN ANATOMY.

Head (capitulum radii) — a cup-like cylindrical cavity, for
articulation with capitellum of humerus, and on its side an ar-
ticulating surface for lesser sigmoid, cavity of ulna and orbicular
ligament, which nearly surrounds it;

Neck (collum radii), the constricted portion below the
head;

Bicipital tuberosity (tuberositas radii), below and to inner
side, divided by a vertical line into a rough surface posteriorly,
for attachment of biceps tendon, and smooth surface anteriorly
for bursa.

The lower extremity, large, expanded and quadrilateral
presents : —

Carpal articular surface (fades articularis carpea), smooth,
concave, triangular depression divided by an anteroposterior
ridge into an outer facet for scaphoid bone and inner for
semilunar ;

Sigmoid cavity (incisura ulnaris), a shallow concavity at
inner side of carpal end, for articulation with ulnar head ;

Styloid process (processus styloideus), projects obliquely
downward from the external surface, for attachment by its apex
to external lateral ligament of wrist joint, and by its base to
insertion of supinator longus muscle. Its outer surface is
marked by two grooves for extensors of thumb ;

The posterior surface of the lower extremity is also marked
by three grooves from without inward for the following: ext.
carpi radialis longior and brevior in first, ext. secundi internodii
in second, and ext. indicis, ext. communis digitorum, and ext.
minimi digiti in third innermost. This surface has also attach-
ment of posterior ligament of wrist.

It articulates with four bones — humerus, ulna, scaphoid
and semilunar.

Its muscular attachments are nine — biceps, supinator longus
and brevis, flexor digitorum sublimis, flexor longus pollicis,
pronator quadratus, extensor ossis metacarpi pollicis, ext. primi
internodii pollicis and pronator radii teres.

Its ossific centers are three — one each for shaft and each
extremity.

The Hand. — The bones of the hand consist of eight carpus,
five metacarpus, and fourteen phalanges; total, twenty-seven
bones.

The carpus (ossa carpi) consist of eight small bones ar-
ranged in two rows — first, or proximal row, from the radial side
inward are scaphoid, semilunar, cuneiform and pisiform; the

OSTEOLOGY.

77

second, or distal row, in same order are trapezium, trapezoid, os
magnum and unciform.

Scaphoid (os naviculare mantis — boat-shaped), largest of
first row, convex above, concave below, articulates with five bones,

Phal,

Cafpni

taearpa*

2* Aw

?Jtem

Fig. 51.
Carpus, metacarpus, and phalanges, dorsal surface.

as follows: superior surface, with radius; inferior, with
trapeziuln and trapezoid; internal, with semilunar above and os
magnum beneath. The external surface has attachment of ex-
ternal lateral ligament of wrist.

78 HUMAN ANATOMY.

Semilunar (os hmatum — half-moon), crescentic in out-
line, presents articulating surfaces for five bones, as follows:
superior convex surface with radius, inferior concave facet with
os magnum and unciform, quadrilateral internal facet with
cuneiform, and external with scaphoid.

Cuneiform (os triquetrum) is wedge-shaped, the base, di-
rected outward, articulates with the semilunar, apex with the
interarticular fibrocartilage of wrist joint, inferior surface with
unciform, and anterior with pisiform ; in all, three bones.

Pisiform (os pisiforme — pea-like) is a small, pea-shaped
bone articulating with anterior surface of cuneiform, and afford-
ing attachment to annular ligament and two muscles, flexor
carpi ulnaris, abductor minimi digiti.

Trapezium (os muXtangulum — a table), a very irregular
bone, articulates above by concave surface with scaphoid ; below,
by surface concave from side to side, convex from before back-
ward, with first metacarpal ; by internal surface with trapezoid,
inferior with second metacarpal. Its dorsal surface is rough;
its palmar grooved by flexor carpi radialis tendon. Muscular
attachments are three — flexor ossis metacarpi, flexor brevis pol-
licis and abductor pollicis.

Trapezoid (os multangulum minus), smallest of second
row, is wedge-shaped, apex palmar ; articulates with four bones —
superior surface with scaphoid, inferior with second metacarpal,
external with trapezium, internal with os magnum and inter-
osseous ligament.

It has one muscular attachment for flexor brevis pollicis.

Os magnum, or capitate (os capitatum), the largest car-
pal bone, consists of a body, neck, and head. The latter projects
from the superior surface and articulates with the scaphoid and
semilunar. The inferior surface articulates with second, third,
and fourth metacarpal bones; the external with trapezoid, and
internal with unciform; in all seven bones.

Muscular attachment for flexor brevis pollicis.

Unciform (os hamatum — hook-like), a wedge-shaped
bone, so named from the hook-like process (hamulus ossis
hamati) projecting from its anterior surface, below its' "articu-
lation with fourth and fifth metacarpals, and above its articula-
tion with semilunar. This process gives attachment to annular
ligament, flexor brevis minimi digiti, flexor ossis metacarpi
minimi digiti, and is grooved for passage of other flexor ten-
dons. External surface articulates with os magnum and inter-
nal with cuneiform.

OSTEOLOGY.

79

Muscular attachments are those to unciform process. Each
carpal bone is developed from a single ossific center.

Fig. 52.
Carpus, metacarpus, and phalanges, palmar surface.

Table of Articulations of Carpal Bones. — Scaphoid; 5;
semilunar, 5 ; cuneiform, 3 ; pisiform, I ; trapezium, I ; trapezoid,
I ; oa magnum, ', ; unciform, 5.

80 HUMAN ANATOMY.

The metacaepus (ossa metacarpalia) are five long bones,
resembling each other, and presenting a shaft (corpus) and two
extremities. Anterior surface is concave, posterior convex;
superior, carpal or proximal extremity or base (basis), irregular
for articulation with carpal bones and with the adjoining bones;
inferior, digital or distal extremity or head (capitulum) , pre-
sents rounded head for articulation with phalanges. The first
metacarpal (os metacarpale I), for thumb is supported on
trapezium, articulates with first phalanx, and has four muscles
attached— first dorsal interosseus, flexor, and extensor ossis
metacarpi pollicis and the flexor brevis pollicis; the second
metacarpal (os metacarpale II) by three, trapezium, trapezoid
and os magnum, articulates also with third metacarpal and
second phalanx, and has six muscles attached — first and second
dorsal interosseus, first palmar interosseus,. flexor carpi radialis,
and extensor carpi radialis longior and the adductor obliquus
pollicis; the third metacarpal (os metacarpale III) supported by
os magnum, articulates also with second and fourth metacarpal
and third phalanx, and has six muscles attached — flexor carpi
radialis, adductor obliquus pollicis, extensor carpi radialis
brevior, adductor pollicis, and second and third dorsal inter-
osseus. The fourth metacarpal (os metacarpale IV) is supported
on os magnum and unciform, articulated with third and fifth
metacarpal and fourth phalanx, and has three muscles attached —
second palmar and third and fourth dorsal interosseus. The
fifth metacarpal (os metacarpale V) supported on unciform,
articulates with fourth metacarpal and fifth phalanx, and has
five muscles attached — flexor ossis metacarpi minimi digiti,
flexor and extensor carpi ulnaris, and fourth dorsal and third
palmar interosseus.

Ossific centers are two for each bone, one each for shaft
and head, except thumb, which has one each for shaft and
base, resembling the phalanges.

Phalanges of the Hand (phalanges digitorum manus).
— Each finger has three phalanges (intemodia), except the
thumb, which has but two. Palmar surface concave, dorsal con-
vex; the superior extremity articulates with head of metacarpal,
and the inferior, concave from side to side, convex from before
backward, articulates with second phalanx, which presents an
opposite arrangement, except in the thumb, where it articulates
with ungual or terminal phalanx.

[Phalanges as a generic term is translated, intemodia;
when applied to the phalanges of the hand, phalanges digitorum

OSTEOLOGY. 81

manus, in contradistinction to the phalanges of the foot, pha-
langes digitorum pedis.]

The second phalangeal articulation is the same, and the
ungual phalanx presents a rough, arrow-shaped extremity.

The muscular insertions to the first row are : to thumb four,
flexor brevis, abductor and adductor pollicis, and extensor primi
internodii; to index two, first palmar and dorsal interosseus; to
middle two, second and third dorsal interossei; to ring, two,
second palmar and fourth dorsal interosseus; to little three,
flexor brevis and abductor minimi digiti and third palmar inter-
osseus.

The insertions to second row are: extensor secundi inter-
nodii and flexor longus pollicis; and to each of the others four,
extensor communis digitorum, flexor sublimis digitorum, with
the addition of extensor indicis to index and extensor minimi
digiti to little.

The insertions to third row are: extensor communis digi-
torum and flexor profundus.

Ossific centers are two for each bone, one each for shaft
and base.

THE LOWER EXTREMITY.

The lower extremity consists of the thigh, leg, and foot. It
is connected to the trunk by the pelvic girdle formed by the hip
bones and sacrum, and contains the following bones : os innom-
inatum, femur, patella, tibia, fibula, seven tarsus, five meta-
tarsus and fourteen phalanges.

The os inxominatum, or hip bone, is a large, irregular
bone forming the lateral and anterior walls of the pelvis, and
consisting of three bones, ilium, ischium and pubes, united
about puberty. It presents

The acetabulum or cotyloid cavity, a deep, cup-shaped cav-
ity, for articulation of the head of the femur — the ischium
forming a little more than two-fifths, the ilium a little less than
two-fifths, and the pubes one-fifth. The bottom of the cavity
presents a circular depression (fossa acetabuH), lodging a mass
of Eat, and giving attachment by its edges to the ligamentum
teres, and continuous below with a deep notch, the cotyloid
aotch {inciswra acetabidi), for attachment of cotyloid and part
of Ligamentum teres, converted into a foramen by the trans-
verse ligament for (he entrance of the nutrient vessels and
nerves. The margin of the acetabulum is deepened by a. fibro-
cartilaginous ring.

The obturator, or thyroid, foramen (foramen obiuratvm) is

82

HUMAN ANATOMY.

an aperture large and ovoidal in the male, small and triangular
in the female, situated on the anterior inferior surface between
the ischium and pubes. It is closed, in the recent state, by a
strong membrane attached to its margins except above exter-
nally, where, a foramen exists for obturator vessels and nerve.

OESCLUII WffUUBI

Fig. 53.
Os innominatum, outer surface.

The ilium (os ilium), broad, flat, and triangular, forms
the greater part of the bone, its base above, its apex at the
acetabulum.

The external surface, or dorsum, concave in front and be-
hind, presents from below upward

OSTEOLOGY. y;{

A groove, just above the acetabulum, for the reflected ten-
don of the rectus femoris muscle;

The inferior curved line, or inferior "luteal line (linea
glutecB inferior), marking the lower border of the gluteus
minimus ;

The middle curved line, or anterior gluteal line (linea

Fig. 54.
Os innominatum, inner surface.

glutem anterior), the longest of the three, marking the lower
border of the gluteus medius ; and

The superior curved line, or posterior gluteal line (linea
glutecB posterior), the shortest, marks the lower anterior border
of the glutens maximus. and from the Burface below which
a i ise a few fibers of the pyriformis.

The upper expanded border forms the- cresl of the ilium

ta Uiaca \ , terminal ing in fronl in

§4 HUMAN ANATOMY.

The anterior superior spinous process {spina iliaca anterior
superior);, giving origin to the sartorius and tensor vaginas
femoris muscles and Poupart's ligament, below which is

The anterior inferior spinous process (spina iliaca anterior
inferior), for the iliofemoral ligament, and the straight tendon
of the rectus femoris muscle; and behind in

The posterior superior spinous process (spina iliaca pos-
terior superior), for the oblique band of the sacroiliac ligament,
and part of the multifidus spina? muscle, below which is

The posterior inferior spinous process (spina iliaca pos-
terior inferior) , for attachment of the great sacrosciatic ligament.

Between the superior and inferior spinous processes, both
anteriorly and posteriorly, is a notch, the former for partial at-
tachment of the sartorius and passage of the external cutaneous
nerve.

The internal concave surface, or venter, presents

The internal iliac fossa (fossa iliaca), lodging the iliacus
muscle, and having a nutrient foramen at its lower part;

Iliopectineal line (linea arcuata), limiting the fossa below,
and separating the false from the true pelvis;

Rough surface, divided into two parts — the posterior por-
tion (tuberositas iliaca), for posterior sarcoiliac ligaments, and
lower auricular or anterior surface (fades auricularis) for ar-
ticulation with sacrum.

The ischium (os ischii) forms the outer back part of pel-
vis, and consists of a body, tuberosity, and ascending ramus.

The external surface of the body forms a little more than
two-fifths of the acetabulum, and presents

A groove (sulcus obturatorius) below, for the tendon of
the obturator externus.

The internal surface is concave and smooth, and forms the
lateral wall of the true pelvis.

The posterior border presents

The spine (spina ischiadica) of the ischium^ projecting
downward, backward, and inward, from below the center for
attachment of the gemellus superior, coccygeus, and levator ani
muscles, and lesser sacrosciatic ligament;

Great sacrosciatic notch (incisura ischiadica major), a deep
notch above the spine converted into a foramen (foramen
ischiadicum majus), by the lesser sacrosciatic ligament, trans-
mitting the pyriformis muscle, superior gluteal nerve, gluteal
vessels, sciatic vessels and nerves, and the internal pudic vessels
and nerves ;

OSTEOLOGY. 85

Lesser sacrosciatic notch (incisura ischiadica minor), be-
low the spine, and between it and the tuberosity, converted into
a foramen (foramen ischiadicum minus) by the great sacro-
sciatic ligament, transmitting the obturator internus muscle and
nerve, the internal pudic vessels and nerves. The lowest por-
tion of the body presents

Tuberosity (tuber ischiadicum), with

Outer lip, for attachment of part of adductor magnus and
quadriceps f emoris ;

Inner tip, for part of great sacrosciatic ligament, erector
penis, and transversus perinaei;

Groove, on inner lip, for internal pudic vessels and nerve;

Intermediate surface, for semimembranosus, semitendino-
sus, biceps, adductor magnus, gemellus inferior and great sacro-
sciatic ligament.

The ascending or inferior ramus (ramus inferior ossis
ischii) passes upward and inward from the tuberosity to join
the descending ramus of the pubes, forming part of the inner
margin of the obturator foramen. It gives attachment to
gracilis, obturator externus, part of adductor magnus, erector
penis and transversus perinaei;

The pubes (os pubis) forms the anterior part of the pelvis
and consists of a body, horizontal ramus, and descending ramus.

The body (corpus ossis pubis) is quadrilateral, and presents

An anterior surface, for attachment of adductor longus and
brevis, and part of gracilis, adductor magnus and obturator ex-
ternus ;

Posterior surface, forming anterior wall of true pelvis and
giving attachment to levator ani and part of obturator internus ;

Spine (tuberculum pubicum) , upon the upper border, for
Poupart's ligament and outer pillar of external abdominal ring;

Iliopectineal line (linea arcuata), continuous with that on
ilium ;

Crest, along the upper border, internal to the spine;

Angle, at the junction of the inner border with the crest
and giving attachment to internal pillar of external ring;

Symphysis, the internal oval border roughened by several
ridges for articulation with opposite bone.

The ascending or superior ramus (ramus superior ossis
pubis) joins t lie ilium, forming the upper part of the obturator
foramen, ami presents at its lower border a

Qroove, for the obturator vessels and nerve.

The descending or Inferior ramus (ramus inferior ossis

gg HUMAN ANATOMY.

pubis) is flat and thin, and joins the ascending ramus of the
ischium.

Each innominate bone articulates with three bones — the sa-
crum, femur, and its fellow of the opposite side.

Its muscular attachments are thirty-three — [ilium], latissi-
mus dorsi, tensor vaginas femoris, obliquus externus, erector
spinas, transversalis, quadratus lumborum, gluteus minimus,
medius, and maximus, rectus, piriformis, iliacus, multifidus
spinas, sartorius — [ischium], obturator externus and intern us,
gemellus superior, coccj^geus, levator ani, semimembranosus and
semitendinosus, biceps, quadratus femoris, adductor magnus,
gemellus inferior, erector penis and transversus perinasi — ■
[pubes], pyramidalis, obliquus internus and externus, psoas par-
vus, pectineus, adductor longus and brevis, gracilis and com-
pressor urethras.

Its ossific centers are eight — one primary for each division
and five epiphyses, one each for crest of ilium, symphysis, tuber-
osity of ischium, anterior spinous process, and acetabulum.

The femur, or thigh bone, is the largest, longest and
strongest bone in the body. In the erect position it inclines
toward its fellow at the knee, being widely separated above,
forming the sides of a triangle, the base of which isi greater in
females from the greater breadth of the pelvis. It consists of
a shaft, an upper and lower extremity.

The shaft (corpus femoris) expanded above and below,
curved and twisted, convex in front, concave behind, is nearly,
cylindrical throughout, and presents

Smooth anterior surface, for origin of crureus and sub-
crureus muscles;

Lateral surfaces, covered by the vasti externus and internus ;

The posterior surface, rough and prominent, has its

Nutrient foramen between the middle and lower two-thirds
directed upward;

Linea aspera, a rough, prominent, longitudinal crest de-
scending from the trochanters along the middle third, bifur-
cating and diverging at the inferior extremity to the condyles,
inclosing

The popliteal space (planum popliteum) , a smooth, trian-
gular space, on which rests the popliteal artery, and which is

Grooved at its inner margin by the femoral artery.

The outer (labium laterale) and inner (labium mediate)
lip of the linea aspera give attachment to the vasti externi and
interni, three adductors, pectineus, biceps and gluteus maximus.

The upper extremity presents the following: —

OSTKOLOOY.

87

ifirUud^

Fio. 66.

The femur, anterior
surface.

Fig. 56.

The femur, posterior
surface.

gg HUMAN ANATOMY.

The head {caput femoris), forming two-fifths of a sphere,
articulates with the acetabulum, having a central oval depression
(fovea capitis femoris) for the ligamentum teres;

Neck (collum femoris), pyramidal, with excavated surfaces,
connects the head with the shaft, the angle of its obliquity to the
shaft varying much from puberty to old age, being, in the adult,
about 130 degrees;

The great trochanter (trochanter major), a large, rough,
quadrilateral eminence, directed upward, outward, and back-
ward, its external surface marked by a diagonal line for inser-
tion of gluteus medius tendon, its outer surface smooth for the
passage of the gluteus maximus tendon, separated by a bursa,
and its superior surface marked by three impressions, from be-
hind forward, for pyriformis, obturator internus and gemelli
muscles. The gluteus minimus is attached to the anterior
border ;

Digital or trochanteric fossa (fossa trochanterics), to the
inner side of the great trochanter, for insertion of obturator
externus tendon;

The lesser trochanter (trochanter minor), a small, conical
projection at the base of the neck posteriorly, and giving attach-
ment to the tendon of psoas magnus muscle, the iliacus being
inserted below;

Anterior intertrochanteric line (linea intertro chant erica)
connects the trochanters in front and gives attachment at its
upper part to the capsular ligament;

Posterior intertrochanteric line (crista intertro chanterica) ,
a much more prominent ridge, connects them behind ;

Tubercle of the femur, a prominence at the junction of the
neck with the great trochanter, is the meeting-place of five mus-
cles— two gemelli, obturator internus, gluteus, minimus and
vastus externus;

Tubercle of the quadratus, about the center of the posterior
intertrochanter line, for the quadratus femoris;

Linea quadrati, passes vertically downward from the mid-
dle of the posterior line, and gives attachment to part of
adductor magnus and quadratus femoris.

The inferior extremity, large and cuboidal in form, pre-
sents : —

External condyle (condylus lateralis), shorter and broader
than the internal, has behind its center the outer tuberosity for
the external lateral ligaments of the knee, and a groove below
the tuberosity for the tendon of the popliteus muscle. It also

OSTEOLOGY. 89

gives origin to the outer head of the gastrocnemius, above which
arises the plantaris muscle ;

The internal condyle (condylus medialis), longer by half
an inch and more prominent (so as to bring them on the same
horizontal plane owing to the obliquity of the shaft), has on
the inner surface the inner tuberosity for the internal lateral
ligament;

Adductor tubercle, at the summit of the internal condyle,
marks the termination of the inner ridge of the linea aspera, and
gives attachment to tendon of adductor magnus;

Depression, above the articular surface of the internal con-
dyle posteriorly, for the origin of the inner head of gastrocne-
mius;

Intercondyloid notch (fossa intercondyloidca) , separates
the condyles behind, and lodges the crucial ligaments;

Trochlear (fades patellaris) is a smooth surface between
the condyles in front and articulates with the patella in front.
The inferior surfaces of both condyles are smooth, continuous
in front, covered with cartilage in the recent state, for articula-
tion with the head of the tibia. The femur articulates with
three bones — innominatum, tibia and patella.

Its muscular attachments are twenty-three (23) — two vasti,
three adductors, gluteus maximus, medius and minimus, pyri-
formis, obturator externus and interims, two gemelli, quadratus
femoris, psoas magnus, iliacus, biceps, pectineus, crureus, sub-
crureus, gastrocnemius, plantaris and popliteal.

its ossific centers are five — three primary, one each for
shaft and each extremity, and one epiphysis for each trochanter.

The patella is a flat, triangular bone, sesamoid in origin,
developed in the tendon of the ^quadriceps extensor, forming the
knee-cap, and entering into the formation of the knee-joint.

The convex anterior surface is roughened by apertures for
nutrient vessels.

The posterior or internal surface (fades articularis) is
divided by a vertical and transverse ridge into three surfaces —
two smooth, articular facets for either condyle of femur above,
the outer being deeper and broader, and a rough surface below,
the apex (apex pateUce) for ligamentum patellae.

The superior border (basis patella') gives attachment to the
rectus and CTureus muscles, tbe internal and external lateral bor-
ders to the vasti internus and externus.

It articulates with the femur.

[ta muscular attachments are four muscles — rectus Eemoris,
crureus, vastus externus and vastus internus.

90 ' HUMAN ANATOMY.

It is developed from a single ossific center.

The tibia, or shin bone, extends on the internal aspect of
the leg from the knee to ankle, and consists of a shaft, upper and
lower extremity.

The shaft (corpus tibia?) is triangular, prismoid, with the
base above.

Its anterior border and internal surface are subcutaneous,
the former forming the shin or crest of the tibia (crista
anterior) .

The posterior surface (fades posterior) presents above an
oblique line (linea popiitea) for the lower border of the pop-
liteal muscle and fascia, and origin of the soleus, and parts of
flexor longus digitorum and tibialis posticus muscles.

It presents just below the oblique line a nutrient canal
(foramen nutricium), the largest in the skeleton, directed
downward.

Its external border, or interosseous ridge (crista interossea)
is thin, for attachment of interosseous membrane.

The external surface and internal borders are covered by
muscles.

The superior expanded surface presents: —

Head, consisting of two tuberosities, internal and external
(condylus medialis and condylus lateralis), each having upon
their upper surfaces a smooth, concave, ovoidal articulating facet
(fades articularis superior) for the condyles of the femur,
separated by

The spinous process (eminentia intercondyloidea) of the
tibia, in front and behind which is impression for crucial liga-
ments, and laterally tubercles for the extremities of the semi-
lunar cartilages;

Tubercle (tuberositas tibial), on the anterior surface of the
head, between the tuberosities, for the insertion of ligamentum
patellae ;

Popliteal notch (incisura popiitea), separating the tuber-
osities posteriorly, for attachment of the posterior crucial
ligament ;

Transverse groove, on the posterior surface of the inner
tuberosity, for insertion of semimembranosus tendon;

Facet (fades articularis fibularis), upon the posterior sur-
face of the outer tuberosity, for articulation of the head of the
fibula.

The inferior extremity, smaller than the superior, is quadri-
lateral, and presents in front a smooth surface for extensor ten-
dons ; behind, a groove for flexor longus pollicis tendon ; exter-

OSTEOLOGY.

91

jtfro*

■^''"/^H.

TrtTTB

I H'U.~.t

Fig. 57.

The tibia and fibula, anterior
surface.

'tyUiSfmem

FIG. 58.

The tibia and fibula, posterior
surface.

92 HUMAN ANATOMY,

nally, a rough, triangular, articular surface, for fibula, and in-
ternally

The internal malleolus (malleolus medialis), which projects
downward, and articulates by its outer surface with the as-
tragalus.

Its inner surface is smooth and subcutaneous; its posterior
border is grooved (sulcus malleolaris) for the tendons of the
tibialis posticus and flexor longus digitorum muscles, and to its
tip is attached the internal lateral ligament.

It articulates with three bones — femur, fibula and as-
tragalus.

Its muscular attachments are twelve — ligamentum patellae,
popliteus, soleus, flexor longus digitorum, tibialis posticus, semi-
membranosus and tendinosus, gracilis, sartorius, tibialis anticus,
extensor longus digitorum and biceps.

It is developed from three ossific centers, one each for shaft,
upper and lower extremities.

The fibula, peroneal, or calf-bone, is a long, slender bone
on the outer aspect of the leg, and consists of a shaft, upper and
lower extremity.

The shaft (corpus fibulce) is prismoidal, four-sided, twisted
on itself, and arched backward. Its antero-internal border, or
interosseous ridge (crista interossea), gives attachment to the
interosseous membrane. The postero-internal border (crista
medialis), called also oblique line, and the other surface and
borders give attachment to all the muscles except the biceps.

Nutrient foramen, about the middle of the anterior-internal
surface, is directed downward.

The superior extremity presents a neck, supporting a
rounded, irregular head (capitulum fibula), which articulates
by a flattened facet on its inner surface with the tibia, and is
prolonged upward on its outer side by the styloid process (apex
capituli fibula), giving attachment to the biceps tendon and the
external lateral ligament of the knee.

The inferior extremity expands into the external malleolus
(malleolus lateralis), with its convex internal surface for ar-
ticulation with astragalus, outer convex surface subcutaneous,
and posterior border deeply grooved (sulcus malleolaris) for
tendons of peroneus longus and brevis muscles.

To the summit is attached the middle fasiculus of the ex-
ternal lateral ligament, and to rough depressions in front and
behind the anterior and posterior fasciculi.

It articulates with two bones, tibia and astragalus.

OSTEOLOGY. 93

Its muscular attachments are nine : soleus, biceps, three
peronei, tibialis posticus, flexor longus ballucis, extensor longus
digitorum and extensor longus hallucis.

It is developed from three ossific centers, one each for shaft,
head and malleolus.

THE FOOT.

The bones of the foot consist of seven tarsus, five metatar-
sus, and fourteen phalanges.

The tarsal bones (ossa tarsi) are: calcaneum, astragalus,
cuboid, scaphoid, and internal, middle, and external cuneiform.

They may be arranged into two series, anterior and poste-
rior; the calcis and astragalus behind, and all the others in
front of the calcaneocuboid and astragaloscaphoid joints [Cho-
part's].

Calcaneum, or os calcis, the largest, is irregularly cuboidal.

The superior surface presents two articular surfaces for
the astragalus, separated by a groove for the calcaneoastragaloid
ligament, and internally a projecting process, the sustentaculum
tali, fur calcaneocuboid ligament. The inferior surface, rough
and excavated, presents two tubercles, an outer and inner
tubercle, for muscles and ligaments.

Internal surface is concave, for passage of flexor longus
and tibialis posticus tendons, and plantar vessels and nerves.

External surface presents tubercle {processus trocldearis)
for external lateral ligament of ankle and grooves for peroneal
tendons.

Posterior surface, projecting behind {tuber calcanei), pre-
sents a smooth surface above for bursa and rough below for
attachment of tendo Achillis.

It articulates with astragalus and cuboid.

Muscular attachments are eight: tendo Achillis, plantaris,
tibialis posticus, abductor hallucis, a. minimi digiti, flexor brevis
digitorum, accessorius and extensor brevis digitorum.

Astragalus (tales) is an irregular, short bone, consisting
of body (corpus tali), neck (collum tali), and head (caput tali).
The quadrilateral body presents four articular surfaces, above
for lower extremity of tibia and internal malleolus and external
malleolus; below, two surfaces for os calcis, separated by deep
groove for interosseous calcaneoastragaloid ligament; posteriorly
it presents a deep groove (sulcus m. flexor hallucis longi) for
flexor Longue ballucis tendon; and anteriorly, the rounded con-
vex head supported on neck articulates with scaphoid, and rests
upon calcaneoscaphoid ligament.

94 HUMAN ANATOMY.

It articulates with four bones : tibia, fibula, scaphoid and
os. calcis. It has no muscular attachments.

Cuboid (os cuboideum—cuhe-like) is a small, pyramidal
bone, between the os calcis and the fourth and fifth metatarsal
bones on the outer side of the foot. *

The upper or dorsal surface is rough for ligamentous at-
tachment; the lower or plantar surface is grooved (sulcus m.
peronwi longi) for tendon of peroneus longus, behind which is
a ridge for the long calcaneocuboid ligament, terminating ex-
ternally in the tuberosity of the cuboid (tuberositas ossis
cuboidei).

The external surface has a deep notch, the outer extremity
of the peroneal groove.

The posterior surface has triangular facet for os calcis, the
anterior has two facets, separated by a ridge for the fourth and
fifth metatarsals, and the internal surface has broad, square
facet for external cuneiform, and sometimes a smaller facet for
scaphoid.

It articulates with four and occasionally with five bones.

It has one muscular attachment — part of flexor brevis pol-
licis.

Scaphoid, or navicular bone (os naviculare pedis), is a
boat-like bone placed between astragalus and three cuneiform
bones.

Its posterior concave surface articulates with head of as-
tragalus, its anterior convex surface has three facets for cunei-
form bones; its internal border presents the tuberosity of the
scaphoid (tuberosit as ossis navicularis) for insertion of tibialis
posticus, the only muscular attachment. Its other borders are
roughened for ligamentous attachment.

It articulates with four bones : astragalus and three cunei-
forms.

The cuneiform bones are named from their position the
internal, middle and external.

The internal cuneiform (os cuneiforme primum), the
largest, has its base below, and articulates anteriorly with first
metatarsal, posteriorly with scaphoid, and externally with
second metatarsal and middle cuneiform. The plantar surface
presents tuberosity for insertion of part of tibialis posticus and
anticus tendons, the only muscular attachments. It articulates
with four bones: scaphoid, middle cuneiform, first and second
metatarsals.

The middle cuneiform (os cuneiforme secundum), the
smallest, has its base upward, and articulates posteriorly with

OSTEOLOGY.

95

Tn„trmas$ UruL,n tf-
S\% DICITORWtt

Fig. 59.
The tarsus, metatarsus, and phalanges, dorsal surface.

gg HUMAN ANATOMY.

scaphoid, anteriorly by a triangular facet with second metatar-
sal, and laterally with internal and. external cuneiforms. It has
no muscles attached.

The external cuneiform (os cuneiforme iertium), in-
termediate in size, and more regular, articulates posteriorly with
scaphoid, anteriorly with third metatarsal, internally with
middle cuneiform and second metatarsal, and externally with
cuboid and fourth metatarsal.

Muscular attachments are for flexor brevis pollicis and
tibialis posticus.

The metatarsal bones (ossa metatarsalia) have the same
general form, as the metacarpal bones of hand, each consisting
of shaft, head and base.

The shaft (corpus) is prismoid and curved, with concavity
below, convexity above.

The head (capitulum) is rounded for articulation with
phalanges, and has tubercles laterally for ligaments and a groove
below for tendon of long flexor.

The base (basis) is wedge-shaped for articulation with the
tarsus and with each other.

The first (os metatarsale I) and strongest articulates at
base with internal cuneiform, at head with phalanx and second
metatarsal, and has three muscular attachments : for tibialis
anticus, peroneus longus and first dorsal interosseous.

The second (os metatarsale II) is wedged in by base be-
tween three cuneiform bones, articulates with second phalanx,
first and third metatarsi, and has three muscular attachments :
for adductor hallucis, first and second interosseous.

The third (os metatarsale III) articulates with external
cuneiform below and second and third metatarsi and third
phalanx, and has four muscular attachments : for adductor hal-
lucis, first plantar, and second and third dorsal interossei.

The fourth (os metatarsale IV) articulates at base with ex-
ternal cuneiform and cuboid and at extremity with 'third and
fifth metatarsal and fourth phalanx, and has four muscular at-
tachments: for adductor hallucis, third and fourth dorsal, and
second plantar interossei.

The fifth (os metatarsale V) has marked tubercle on outer
side. It articulates with cuboid, fourth metatarsal, and fifth
phalanx, and has five muscular attachments : for flexor brevis
minimi digiti, peroneus brevis and tertius, fourth dorsal and
third plantar interosseus.

The phalanges of the foot (phalanges dig it o rum pedis)
have same general characteristics as in hand, but are compressed

OSTEOLOGY.

97

ku*a mi.) rtuiohf

Fig. 60.
The tarsus, metatarsus, and phalanges, plantar surface.

98 HUMAN ANATOMY.

from side to side instead of from before backward ; and have the
following nomenclature applied : first or proximal phalanx
(phalanx prima) ; second phalanx (phalanx secunda) ; ungual
or distal phalanx (phalanx tertia) . The muscular insertions to
first row are : to great toe, transversus pedis, extensor brevis
digitorum, adductor, abductor and flexor brevis hallucis; to
second, first and second dorsal interosseus; to third, third dor-
sal and first plantar interosseus; to fourth, fourth dorsal and
second plantar interosseus; to fifth, abductor and flexor brevis
minimi digiti and third plantar interosseus. To second row :
to great toe, flexor and extensor longus hallucis; to remaining
toes, extensor longus and brevis digitorum, flexor brevis digi-
torum and lumbricales. To third row, or ungual phalanges:
flexor longus and extensor longus and brevis digitorum.

The ossific centers are one each for the tarsus, excepting the
os calcis, which has an epiphysis for posterior part, and two
each for metatarsals and phalanges. These latter are arranged
in phalanges, one each for shaft and base, and in metatarsals,
one each for shaft and head, excepting great one, which has one
each for shaft and base.

Sesamoid bones (ossa sesamoidea) are small, osseous
masses, cartilaginous in early life, developed in the tendons to
relieve pressure. They are of two kinds — -those over articular
surfaces of joints, as patella; and those applied to the surfaces
of bones, as in tendon of peroneus longus in the groove of
cuboid bone.

OSTEOLOGY.

99

Name.

Yertebr.e.

Atlas (3).
Axis (6).

Seventh Cervical.

Lumbar Verte-
brae (2).

Sacrum (35).
15.

10.

6.
4.

Coccyx (7).

f'KANIAl,

Bones.
Occipital (7).

Parietal (1),

TABLE OF OSSIFICATION.

Centers.
Primary: —
1 for each lamina.
1 for each process.
1 for body.
Secondary Centers: —

1 for each transverse process.

2 for end of spinous process.
Additional Plates: — ■

1 epiphyseal plate on upper and
under surface of bod v.

1 for each lateral mass.

1 epiphysis for anterior arch.

1 for lower part of body.

1 for each lamina.

2 for lateral processes.

1 for apex of odontoid process.
1 for anterior and costal part of
transverse process.

1 for each tubercle of superior
articular process.

3 — 1 each for body

and upper and lower epiphys-
eal plate.

2 — 1 for each arch.

2 for eacli lateral mass of the fust
three vertebrae.

Each lateral surface has one epi-
physeal articulation and ad-
joining edge.

1 for each piece.

1.

2.

3.

4.

4 for tabular or epi-oceipital.
1 for each condylar portion.

1 for basilar portion.
From membrane.

^iiiL'le center at parietal eminence

Time of
Appearance.

6th week.
8th week.
16th year.

21st year.

All unite by 30th

year.
8th week.
1st year.
6th month.

6th fetal month.

6th fetal month :
joins 5th or
6th rear.

8th or 9th week.
16th year, and

un'tes 18th or

20th vear.
6th or 8th month;

joins 2d to 6th

vear.

18t.li
year,

to 25th

Birth.

5th to 10th year.
10th to 15th year.
15th to 20th vear.

8th fetal week.

-1 tli in 6th year:
joined In sphe-
noid 18th to
25t'i year.

7th to 8th fetal

week.

100

HUMAN ANATOMY.

"Name.
Frontal (2).

Temporal (10).
Sphenoid (14).

Centers.
1 for each lateral portion.
From membrane.

1 for squamous process.

1 for auditory process.
6 for petromastoid.

2 for styloid process.
8 for postsphenoid.

1 for each greater wing and ex-
ternal pterygoid plate.

1 for each internal pterygoid plate.

2 for posterior part of body.

1 for each lingula.
6 for presphenoid: —

1 for each lesser wing.

2 for anterior portion of body.
1 for each sphenoturbinal.

Ethmoid (3),

1 for each lateral mass.
1 for lamella.

Face.
Nasal. 1 for each bone.

Superior Maxillae

(4). 1 premaxilla.

1 prepalatine portion.

Lachrymal.
Malar.
Palate.

Inferior Turbi-
nated.

1 maxillary portion.

1 malar portion.

A single center.

Single center.

Single center at junction of plates.

Single center.

Vomer. Single center, but two laminae.

Inferior Maxilla. Probably several centers; at birth
consists of two halves.

Body.
Hyoid (5).

1 for body and for each cornu.

Time of
Appearance.

7th to 8th week.

United by 4th
year.

2d month.

Later.

5th or 6th month.

1 for base ap-
pears before
birth and one
after birth.

Appear from 8th
week to third
year, and union
of all parts is
accom p 1 i s h e d
by the 20th
year, and with
occipital, 18th
to 25th year.

4th to 5th fetal
month.

Unite about 2d
year.

6th week.

Very early.

Antrum appears
about fourth
fetal month.

7th week.
6th week.
2d fetal month.

Middle of fetal
life.

8th week.

Very early, be-
ing second in
order.

3 months after
birth.

OSTEOLOGY.

101

Name.
Sternum (6),

Ribs (3).

Upper
Extremity.

Clavicle (2).
Scapula ( 7 ) .

Humerus ( 7 ) .

Ulna (3).
Radius (3).

Carpus.

Centers.

1 for manubrium.

4 for gladiolus.

1 for ensiform appendix.

1 for each shaft, head, and tuber-
cle, excepting the last two,
which have but 2, the tuber-
cles being absent.

1 for shaft.

1 for sternal extremity.

1 for body.

2 for coracoid process.

2 for acromion process.

1 for posterior border.

1 for inferior angle.

1 for shaft.

1 for head.

1 for tuberosities.

1 for radial head.

1 trochlear portion.

1 for each condyle.

1 for shaft.

1 for olecranon.

1 for lower extremity.

1 for shaft.

1 for upper extremity.

1 for lower extremity.

Each lias single center: —
I •- magnum.
I 'nciforni.
Cuneiform.

Trapezium and semilunar.
Scaphoid.
Trapezoid.
1'isiform.

Time of
Appearance.
Middle of fetal
life.

Before vertebrae.
Epiphysis for
tubercle ap-
pears from
16th to 20th
year, and
unites about
25th.

About 30th day.
2d month.

Completed be-
tween 20th and
25th year.

!-'tli week.

Upper extremity
ossifies 2d to
4th year.

Complete about

20th year.
8th week.
10th year.
4th year.
Soon after hu-
merus.
5th year; unites

17th to 18th

year.
2d year; unites

20th year.
Upper extremity

joins 16th year;

lower, 20 th

year.

1st year.
1st year.
3d year.
5 tli year,
fitll year.
8th year.
12th year.

102

HUMAN ANATOMY.

Name.
Metacarpus ( 2 ) .

Phalanges ( 2 ) .

Centers.
Centers for each: —
1 for shaft and

1 for each distal extremity ex-
cept thumb, which has one
each for shaft and base.
1 each for shaft and base.

Time of
Appearance.

8th or 9th week.
3d year, and

unites about

20th year.
8th week, and

unites 18th to

20th year.

Lower

Extremity.

Os Innominata

(8).

3 Primary: —

Ilium.

Same as verte-
• brse, 6th week.

Ischium.

3d month.

Pubes.

4th or oth month.

5 Secondary: — •

1 crest of ilium.

Puberty.

1 anterior inferior

spinous proc-

ess.

"

1 tuber ischii.

it

1 symphysis pubis.

"

1 acetabulum.

13th or 14th year;
completed 25th
year.

Femur (5).

1 for shaft.

5th week.

1 for lesser trochanter.

End of 1st year

1 for great trochanter.

9th fetal month.

1 for lower extremity.

4th year.

1 for upper extremity.

13th or 14th year.

Inferior extrem-

ity. The last

is not united

before the 20th

year.

Patella.

Single center.

3d to 6th year;
completed
about puberty.

Tibia (3).

1 for shaft.

7th week.

1 upper extremity.

Birth ; unites
20th year.

1 • lower extremity.

2d year ; unites
18th year.

Fibula (3).

1 for shaft.

8th fetal week.

1 upper extremity.

4th year.

1 lower extremity.

2d year ; the
lower unites
first — about
20th year.

OSTEOLOGY.

103

Name.

Tarsus.

Metatarsus.

Centers.

os calcis: —

1 for body and

1 for posterior extremity.

each for the following: —

Cuboid.

Astragalus.

Scaphoid.

Internal cuneiform.

Middle cuneiform.

External cuneiform.

1 each for shaft

and digital extremity,
except great toe, which is
same as thumb.
Phalanges (2). 1 each for shaft and proximal ex-
tremity.

Time of
Appearance.

6th fetal month.

9th month.
7th month.
4th year.
3d year.
4th year.
1st year.
7 th week.
3d year.

ARTICULATIONS AND LIGAMENTS.

The bones of the skeleton are connected together by articu-
lations or joints.

These consist essentially of the expanded extremities of
bones, covered with cartilage, often separated by interarticular
fibrocartilage, held together by ligaments, and lined by synovial
membrane.

The bone entering into the articular lamella differs from
ordinary bone by its extreme density, without Haversian canals,
its lacunae being much larger, and without canaliculi. It is not
perforated by blood-vessels.

Cartilage is a whitish, highly elastic, non-vascular struc-
ture, forming in the fetus the greater part of the skeleton, and
found in the adult chiefly in the joints, the walls of the thorax,
and certain orifices, as the nostrils, ears, etc.

It is either temporary, becoming ossified later, or perma-
nent, remaining unossified. The latter is divided into three
varieties: articular., in joints covering the ends of the bones;
costal, forming part of the thorax; and reticular, arranged in
plates or lamellae to maintain the shape of parts.

Fibrocartilage consists of a mixture of cartilaginous with
white fibrous tissue. There are four varieties: —

(a) Inter articular, interposed between the joint surfaces;

(b) Connecting, binding bones together as in pubes;

(c) Circumferential, deepening cavities, as glenoid cavity of
shoulder; and

(d) Stratiform, lining grooves for tendons.

Synovial membranes are of three kinds: articular, lining
the cavities of movable joints throughout except the surface of
the cartilage; bursal, irregular cavities interposed at convenient
positions to alleviate friction; from their contents they may be
either mucous or synovial; and vaginal synovial membranes, or
sheaths, surrounding tendons and diminishing friction.

Synovia is a transparent, viscid liquid, albuminous in its
nature.

The articulations consist of three (3) classes: diarthrosis,
movable; synarthrosis, immovable; and amphiarthrosis, mixed.

(104)

ARTICULATIONS AND LIGAMENTS. I(j5

1. The diarthrosis are subdivided into: —

Arthrodia, gliding joint, as superior tibiofibular;

Enarthrosis, ball-and-socket joint, as shoulder and hip;

Ginglymus, hinge-joint, as knee and ankle;

Troehoides, a ring surrounding a pivot, as atloaxoid joint and
superior radioulnar.

Condyloid, elliptical cavity receiving an ovoid head, as wrist joint.

Reciprocal reception, a concavoconvex articulation, as carpometa-
carpal joint of thumb.

8. Synarthrosis, surface immovably connected by fibrous
membrane without synovial membrane.
They are divided into: —

Sutura, bones interlocking with one another;

Schindylesis, a fissure in one bone receiving a plate of bones, as
between vomer and sphenoid;

Gomphosis, a socket with a pivot inserted, as in alveolar cavities
for teeth.

Synchondrosis, a temporary joint in which the connecting medium
is cartilage.

The sutura may be either true, sutura vera, or false, sutura
notha, the former having three divisions : dentata, tooth-like
processes, as interparietal suture; serrata, saw-like edges, as
interfrontal suture; limbosa, dentated processes and beveled
margins, as frontoparietal ; the latter two divisions : —

Squamosa, overlapping beveled margins, and

Harmonia, by union of roughened surfaces, as intermaxillary
suture.

3. AmpliiartJirosis, bony surfaces connected by fibroearti-
lage, with or without synovial membrane, as between vertebral
bodies, and pubic symphysis.

MOTIONS IN Joints. — Joints admit of four (4) distinct
varieties of motion: —

(a) Gliding movement, between contiguous surfaces;

(6) Angular movement, as flexion, extension, adduction and ah
duction;

[c) ( ircumduction, as in true enarthrosis;

(d) Rotation on its own axis, as between the atlas and axis.

Ti;.m I'Oito.M axi LLARY, or 1 em | M n'oiiuiiid ibular articulation
(articulatio mandibidaris) , is formed by condyle of lower jaw,
below articulating with glenoid cavity of the temporal bone and
eminentia articularis above. It is a double arthrodial joint.

Ligaments. — External Lateral (ligamentum t'emporomm-
dibulare). Origin, tubercle on outer edge of zygoma ; insertion,
outer Bide of neck of condyle.

106 " HUMAN ANATOMY.

Internal Lateral (ligamentum sphenomandibulare) . — -
Origin, spinous process of sphenoid; insertion, lower circumfer-
ence of inferior dental foramen.

Capsular (capsula articularis) . — Origin, circumference of
articulation; insertion, neck of condyle.

Interarticular fibrocartilage (discus articularis) is within
cavity; external pterygoid muscle attached to its inner edge.

Synovial membrane is divided into two by cartilage.

Intermaxillary ligament passes from external pterygoid
process to coronoid.

Styloniaxillary or Stylomandibular Ligament (ligamentum
stylo mandibular e) . — Origin, styloid process; insertion, inner
surface of angle of jaw. Nerves are derived from the auriculo-
temporal and masseteric branches of the inferior maxillary.

Articulations of Vertebral Column. — These are formed
between the contiguous surfaces of the vertebral bodies and
articular processes, inclosed in capsular ligaments, and con-
nected with the following ligaments : —

The anterior common ligament (ligamentum longitudinale
anterius) extends from the front of the body of the axis down
the anterior surface (ventral) of the spine to the sacrum, being
expanded opposite, and attached to each intervertebral connect-
ing fibrocartilage;

The posterior common ligament (ligamentum longitudinale
posterius) descends along posterior surfaces (dorsal) of bodies
from axis to sacrum within spinal canal. It also expands
opposite and adheres to intervertebral substance;

Intervertebral substance (fibrocartilagines intervertebrales) ,
disks of varying size, twenty-seven in number, composed of
decussating fibers of fibrocartilage, arranged in crescentic
laminge with central, semipulpy substance, separate the verte-
bras;

Ligamenta subflava (ligamenta flava, ligamenta ihtercru-
ralia) descend in pairs, twenty-three on either side, from one
lamina to another, from axis to sacrum, inclosing spinal canal;

Supraspinous ligament (ligamentum supraspinal^) strong
cord descending from one vertebra to another, from vertebra
prominens (seventh cervical) to sacrum. Its continuation in
cervical region forms ligamentum nucha;

Interspinous (ligamenta inters pinalia) stretch between
spinous processes throughout dorsal and lumbar regions;

Intertransverse (ligamenta mtertransversaria) , between
transverse processes in lower dorsal and lumbar regions.

ARTICULATIONS AND LIGAMENTS. 107

The arteries are derived from ascending cervical and verte-
bral in cervical, intercostals in dorsal, and lumbars in lumbar
regions.

The nerves are from spinal nerves in each region.
Atloaxoid or atlaxtoaxoideax articulation (articula-
tio atlantoepistrophica) consists of of four joints, the two lateral
joints being arthrodia, and that between the odontoid process
and arch of atlas and transverse ligament — a diarthrosis rota-
toria being double, one in front, atlo-odontoid, and one behind,

bdontotransverse. The ligaments are: —

Anterior atloaxoid, or anterior atlantoaxial, two — super-
ficial and deep, connecting anterior borders together;

Posterior atloaxoid, or posterior atlantoaxial, connecting
the arches of the atlas and axis posteriorly, and pierced laterally
by the second spinal nerve;

Capsular (eapmlce articulares) , two, connecting the articu-
lating processes laterally, and lined with synovial membrane;

Transverse, or cruciform (ligamentum transversum atlan-
tis), arises from the tubercle on one side of the lateral mass,
passes across the back of odontoid process to be inserted into
the opposite tubercle.

The arteries are from vertebral, nerves from second cervical,
or from loop between it and suboccipital.

Occipitoatlotd (articulatio atlanto-Oi ipitalis). — Anterior
occipitoatloid (membrana atlanto-occipitalis anterior) — two,
superficial and deep, connecting the tubercle and upper border
of anterior arch or atlas with basilar process and margin of
foramen magnum of occiput.

Posterior occipitoatloid, or occipitoatlantal ligament (mem-
brana atlanto-occipitalis posterior — membranous), connects the
upper border of posterior arch of atlas with posterior margin
of foramen magnum.

Lateral ligaments, two bands connecting transverse process
of atlas with jugular process of occipital.

Capsular ligaments (capsules articulares) connect the artic-
ular processes of atlas with condyles of occiput.

The arteries are from rertebral; nerves, from suboccipital.
OCCIPITOAXOID. — Occipitoaxoid is a broad hand, the con-
tinuation of posterior common ligament, extending from the
body of the axis to basilar groove of occipital.

odontoid, or check (ligamentum alaria), pass upward and
outward from the summit of tin,' odontoid process, to he inserted
into the inner side of the occipital condyles.

108 HUMAN ANATOMY.

Ligamentum suspensorium, or central occipito-odontoid
{ligamentum apices dentis), arises from the center of the trans-
verse ligament at the apex of the odontoid process, and passes
upward, to be inserted into the anterior margin of the foramen
magnum.

Occipitocervical, or cervicobasilaris {membrana tectoria,
apparatus ligamentosus colli, posterior occipitoaxoid ligament),
arises from the bodies of the third cervical and axis, and is
inserted into the basilar groove of occipital.

The arteries are from vertebral; the nerves from suboc-
cipital.

Capsular Ligaments. — Throughout the spine the articula-
tions between the facets of the articular processes are surrounded
by capsular ligaments, making twenty-five pairs in all.

Costovertebral Articulations {articulationes costoverte-
brales). — The costovertebral have each a double arthrodia be-
tween the head of the rib and the bodies of the two adjacent
vertebrae, except the first, tenth, eleventh and twelfth ribs,
which have each but a single joint.

Anterior Costovertebral, or Stellate Ligament {ligamentum
capituli costm radiatum). — Origin, head of the rib; insertion,
into body of vertebra above and below, and interarticular carti-
lage between.

Interarticular costovertebral {ligamentum capituli costw
interarticulare) is within the capsular ligament, from the crest
on the head of the rib to the intervertebral substance.

Capsular ligament {capsula articularis) surrounds the artic-
ular surfaces.

Costotransverse articulations are united by three ligaments
— anterior, middle, and posterior costotransverse ligaments —
extending between the tubercles of the ribs to the transverse
process below. Arteries, the intercostals ; nerves, anterior
branches of spinal.

Costosternal Articulations (articulationes sternocos-
tales). — These are connected by arthrodia excepting the first,
which is a synarthrodia.

Anterior chondrosternal ligaments {ligamentum sternocos-
tal radiatum) connect the chondral and sternal surface in
front ;

Posterior chondrosternal {ligamentum sternocostal^ radia-
tum) connect them behind.

Capsular ligaments {capsula articularis) surround all, and
synovial membranes are present in all but the first, while the
second has an interarticular cartilage interposed.

ARTICULATIONS AND LIGAMENTS. 1Q9

The chondroxiphoid (Ugamentum costoxiphoidea) ligament

connects the cartilage of the seventh and sometimes the sixth
rib with the xiphoid appendix.

Interchondral and Costochondral Articulations (articula-
tiones interchondrales) . — The ribs are connected with their car-
tilages by the periosteum covering them. The cartilages of the
sixth, seventh, and eighth ribs, and sometimes the fifth and
ninth, are connected by external and internal interchondral
ligaments (ligamenta intercostalia externa et interna), held
together by capsular ligaments and lined with synovial mem-
brane.

Ligaments of Sternum. — The first and second portions
of the sternum are articulated by an amphiarthrodial joint,
sometimes a diarthrodial joint, connected by the external inter-
sternal and internal intersternal ligaments, and lined with
synovial membrane.

The third portion, or enisform cartilage, is united to the
gladiolus by a synarthrodia! joint.

THE THORAX.

The thorax is a conical osteocartilaginous framework,
formed by the dorsal vertebrae behind, the ribs, intercostal mus-
cles, and costal cartilages laterally, and the sternum in front.

The apex, or superior opening (apertura thoracis superior),
is bounded behind by the first dorsal vertebra, laterally by the
first rib, and in front by the npper border of the sternum.

It transmits the following structures: —

Esophagus, trachea, thoracic duct (on the left side), lymphatic
vessels of right side of chest and of surface of liver, innominate artery
(right side), left common carotid artery, left subclavian artery, right
and left superior intercostal arteries, right and left internal mammary
arteries, thyroidea ima artery (if present), right and left inferior thy-
roid veins, right and left innominate veins, right and left phrenic nerves,
right and [eft pneumogastric nerves and their cardiac branches, left
recurrent laryngeal nerve, right and left first dorsal nerves, right and
left sympathetic nerves and their cardiac branches, apices of lungs and
pleurae, remains of thymus, and deep cervical fascia passing to peri-
cardium.

The longus colli, Bternohyoides and sternothyroides on both Bides
also pass I trough it.

The inferior opening {apertura thoracis inferior) is formed
by the last dorsal vertebra behind, the last rib laterally, and the
ensiform cartilage in front. It Is filled in by the diaphragm.

The cavity (carum thoracis) of the thorav contains the
following structures: the heart and great vessels, trachea, hron-

110 HUMAN ANATOMY.

chi and lungs, azygos and bronchial veins, internal mammary
arteries, pneumogastric, phrenic and splanchnic nerves, thoracic
duct, esophagus, lymphatic vessels and glands (vide medias-
tinum).

Spine and Pelvis. — Sacrovertebral articulation. In addi-
tion to those of the spine, given above, there are two ligaments
connecting the last lumbar vertebra with the sacrum : —

Lumbosacral ligament, arising from the transverse process
of the last lumbar vertebra, and inserted into the base of the
sacrum ;

Iliolumbar ligament (lig amentum Violumbale), arising
from the apex of the transverse process of the last lumbar verte-
bra, and inserted into the crest of the ilium. The arteries are
from last lumbar, iliolumbar and lateral sacral. The nerves
are branches of fourth and fifth lumbar and sympathetic.

Sacroiliac articulation (articulatio sacroiliaca) , between the
articular surfaces of the sacrum and ilium, is an amphiarthrodial
joint connected by

The anterior sacroiliac ligament (ligamenia sacroiliaca on-
teriora), crossing between anterior surfaces of the two bones;

Posterior sacroiliac ligament (ligamentum sacroiliacum
posterius) , the stronger, passes in different directions between
the posterior surfaces of the two bones, firmly binding them
together. One of these, stronger than the others, passes from
the posterior superior spinous process to the third sacral trans-
verse process. It is called

The oblique sacroiliac ligament (ligamentum sacroiliacum
posterius longum).

The arteries are from gluteal, sacral, spinal and iliolum-
bar; the nerves from lumbosacral and posterior sacral cords.

Sacroiscliiatic Articulation. — -The os innominatum and sa-
crum are united by two important ligaments — the great sacro-
sciatic (posterior) ligament,^ and the lesser sacrosciatic (anter
rior) ligament.

The great sacrosciatic ligament (ligamentum' sacrotubero-
sum) arises from the fourth and fifth transverse tubercles of
the sacrum, from spine of ilium, sacrum and coccyx, and passes
downward, outward and forward, to be inserted into the inner
margin of the tuberosity of the ischium, being prolonged for-
ward as the falciform ligament (processus fahiformis) protect-
ing the internal pudic veins and nerves.

It converts the sacrosciatic notch into the lesser sacro-
sciatic foramen, transmitting the obturator internus muscle and
nerve, the internal pudic vessels and nerves.

ARTICULATIONS AM) LKiA.M K.X'I'S.

Ill

The lesser sacrosciatic ligament (ligamentum sacrospino-

sum) arises from the lateral margin of the sacrum and coccyx,
and is inserted into the spine of the ischium. It converts the
sacrosciatic notch into the greater sacrosciatic foramen (foramen
i xhiadicum majus), transmitting the pyriformis muscle, gluteal
vessels, superior gluteal nerve, sciatic vessels and nerves, and the
internal pudic vessels and nerves.

Sacrococcygeal articulation (symphysis sacrococcygea) is
an amphiarthrodial joint, resembling the vertebral, having an
interarticular fibrocartilage, and connected together by

Pig. 61.

1, manubrium; 2, gladiolus; ?,, xiphoid appendix; 4, first dorsal
vertebra; 5, last dorsal vertebra; 6, first rib.

An anterior sacrococcygeal ligament (ligamentum sacra-
coccygeum anterius), and

A posterior sacrococcygeal ligament (ligamentum sacro-
coccygeum posterius), continuations respectively of the anterior
and posterior common ligament.

Lateral sacrococcygeal, intertransverse (ligamentum sacro-
coccygeum laterale), and intercornual ligaments connecting the
rudimentary tran verse processes and the cornua together.

The arteries are from lateral and median sacral:

Tin- nerve branches of coccygeal, fifth sacral, and posterior
<li\i-ions of fourth sacral.

112 HUMAN ANATOMY.

Pubic Articulation. — This is an amphiarthrodial joint,
known also as the symphysis pubis (symphysis ossium pubis) .

It is connected by the

Anterior pubic ligament (Jig amentum pubicum anterius)
in front;

Superior pubic ligament (Jigamentum pubicum superius)
above ;

Posterior pubic ligament (Jigamentum pubicum posterius)
behind ;

Subpubic ligament (lig amentum arcuatum pubis) below,
forming the boundary of the pubic arch.

FIG. 62.

A A, anteroposterior diameter; B B, transverse diameter; C C,
oblique diameter; 1, sacroiliac ligament; 2, anterior or lesser sacro-
sciatic ligament; 3, posterior or great sacrosciatic ligament.

Within the joint an interposed fibroeartilage, or interpubic
disk (lamina fibrocartilaginea interpubica) , separates the bones.

The obturator membrane, or ligament, closes the obturator
foramen, and affords attachment for the external and internal
obturator muscles and allows passage at its upper outer part,
for the obturator vessels and nerves.

THE PELVIS.

The pelvis is a strong, bony basin, formed at the lower end
of the vertebral column by the articulation of the sacrum and
coccyx posteriorly with the ossa innominata laterally.

It is divided into a false and true pelvis by the iliopectineal
line.

The false pelvis (pelvis major) is situated above the ilio-
pectineal line, and corresponds to the expanded iliac fossae,

ARTICULATIONS AND LIGAMENTS. 113

being bounded laterally by the ossa ilii, and having in front and
behind wide intervals.

The true pelvis (pelvis minor) includes all that portion
below the linea iliopeetinea, and presents a cavity, superior cir-
cumference or inlet, and an inferior circumference or outlet,

The inlet (apertura pelvis superior) is heart-shaped, being
bounded behind by the promontory of the sacrum, laterally by
the linea iliopeetinea, and in front by the crest and spine of
the pubes.

Its principal diameters in the female are : —

Anteroposterior or conjugate (conjugata) , from symphysis to
vertebral angle, four and three-fourths inches; transverse (diameter
transversa) across the widest part, five and one-fourth inches; and ob-
lique (diameter obliqua) , from the iliopectineal eminence in front to
the sacroiliac sympnysis behind, five inches; the anatomical conjugate
(conjugata anatomica) from the sacrovertebral angle to the top of the
symphysis and measures about four and three-fifths inches; the true,
available or obstetric conjugate (conjugata gyiurcologica) is taken from
the sacrovertebral angle to the nearest point upon the symphysis, and
in the female averages about four and three-eighths inches. In the
male, these measurements are about three-fourths of an inch less in
every diameter.

It transmits the following structures: —

Viscera and Ducts.

1. Small intestines. -3. Urachus and obliterated hypo-

2. Rectum. gastric arteries.

3. Vasa deferentia (in male), 6. Uterus (pregnant).

round ligaments (in female). 7. Bladder (distended).

4. Ureters. 8. Peritoneal coverings.

Vessels.

1. Superior hemorrhoidal. 6. Obturator (from deep epigas-

2. Internal iliac. trie).
:>,. Sacra media. 7. Ovarian.

4. Iliolumbar. 8. Pubic branches from external

.">. Brancb.ee of vasa intestini ten- epigastric arteries.

uia. 9. Lymphatic vessels.

Nerves.

1. Sympathetic :5. Obturator.

1. Branches from hypogastric 4. Lumbosacral cord.

pleXUS.

The cavity of the pelvis is bounded behind by the sacrum
and coccyx, in' fr-mf by the symphysis, and laterally by the body
of the ischium, forming a curved canal, widest in the middle.

8

H4 HUMAN ANATOMY.

It contains, in the recent state, the organs of generation, rectum,
bladder, and their vessels, nerves, ducts, etc. Its axis corre-
sponds to the concavity of the sacrum and coccyx.

Its depth in front, at the symphysis, is about one and a
half inches in the middle axial line, three and a half behind, in
males four and a half to possibly five and a half.

The outlet of the pelvis (apertura pelvis inferior) is
bounded by three prominences, the tuber ischii laterally and the
coccyx behind ; separated by three notches, the subpubic arch in
front and the sacrosciatic notches posteriorly.

Its principal diameters are : transverse, three and a half
inches in male, four and three-fourths in female; anteropos-
terior, three and three-fourths in male, four and one-half in
female.

In the erect position the pelvis is placed at an angle of
from sixty to sixty-five degrees with the ground.

Differences of Sex. — The male pelvis is characterized by
the strength of the bones, by prominent muscular impressions,
by the depth and narrowness of the cavity, the large obturator
foramen, and the acute angle of the subpubic arch.

The female pelvis is characterized "liytlfe lightness of the
bones, the slight muscular impressions, by the shallow, expanded
iliac fossae, the increased size of the cavity in every diameter,
and the obtuse angle of the subpubic arch.

ARTICULATIONS OF THE UPPER EXTREMITY.

The sternoclavicular articulation (articulatio sternodavicu-
laris) is an arthrodial joint, formed between the sternal end of
the clavicle and the sternum and first rib, being divided into
two cavities by an interarticular fibrocartilage. Its ligaments
are: —

Anterior sternoclavicular (ligementum sternoclavicular ~e)
is a broad band passing between the articular margins, attached,
to the interarticular cartilage and two synovial membranes, and
forming the front part of the capsular ligament;

Posterior sternoclavicular passes over the posterior aspect of
the joint and corresponds to the former ;

Interclavicular {ligamentum inter claviculare) passes from
the sternal end of the clavicle on one side across the suprasternal
notch to the clavicle of the opposite side ;

Costoclavicular, or rhomboid (ligamentum costo clavicu-
lare), passes from the rhomboid impression on the inferior sur-

ARTICULATIONS AM) LIGAMENTS.

115

face of the clavicle to the upper surface of the first costal
cartilage.

The synovial membranes form two sacs separated by the
interarticular cartilage.

The arteries are from muscular branch of suprascapular
and contiguous muscular branches;

The nerves, from descendens noni.

Acromioclavicular articulation {articulatio acromio-
clavieularis) is an arthroidal joint formed between the acromial
extremity of the clavicle and the acromial process of the scapula.
Its ligaments are : —

1, superor acromioclavicular ligaments; 2, eoracoclavicular liga-
ments; 3, coracoacromial ligaments; 4, transverse ligament; 5, cap-
sular ligament; 6, coracohumeral ligament; 7, tendon of biceps.

The superior acromioclavicular (ligamentum acromio-
claviciUare) connect the adjoining parts of the superior surfaces
of the clavicle and acromion process;

Inferior acromioclavicular, connecting the inferior surfaces;

Coracoclavicular (lijamentum coracoclaviculare) consists of
two parts : —

Trapezoid ( ligamen I h m trapezoideum) } broad, square,
arises from upper surface of coracoid process, and is inserted
into oblique line on under surface of clavicle; and

Conoid {ligamentum conoideum), behind and internal,
arises from base of coracoid process, and is inserted into conoid

tubercle on under side of clavicle and a line infernal to it.

The ligaments surrounding the joint form a capsule.

116 HUMAN ANATOMY.

The arteries are from anterior circumflex, acromial thora-
cic and suprascapular.

The nerves are anterior circumflex and suprascapular.

The scapula has, also,

The coracoacromial (ligamentum coracoacromiale) , arising
from the outer border of the coracoid process and inserted into
.the summit of the acromion, and

Transverse (lig amentum transversum scapula superius), a
ligamentous band bridging the suprascapular notch, converting
it into a foramen for suprascapular nerve.

The si-iouldee joint (articulatio humeri) is an enar-
throdial joint, formed above by the glenoid cavity of the scapula
and below by the head of the humerus. Its ligaments are :
glenoid, coracohumeral and capsular.

The glenoid (labrum glenoidale) surrounds the edge, deep-
ens the glenoid cavity, and is continuous above with the long
head of the biceps tendon.

The capsular ligament (capsula articularis) , extensive and
loose, arises above it from circumference of glenoid cavity be-
hind the ligament, is attached below to the anatomical neck of
humerus, and is pierced by tendons of two or three muscles.

The coracohumeral, or accesory (ligamentum coracoJiu-
merale), is a fibrous band which extends obliquely downward
and outward from the coracoid process to the anterior part of
great tuberosity, strengthening the capsular ligament.

The synovial membrane is extensive and reflected upon the
tendon of biceps, which is inclosed in a tubular sheath of syno-
vial membrane (vagina mucosa intertubercularis) , and upon the
infraspinatus, and subscapularis muscles.

Its arteries are derived from the subscapular, suprascapular,
dorsalis scapulas, anterior and posterior circumflex;

Its nerves, from the subscapular, suprascapular and cir-
cumflex.

The 'elbow joint (articulatio cubiti) is a ginglymoid
articulation formed above by the lower extremity of humerus,
below by upper extremities of ulna and radius. Its ligaments
are external and internal lateral, anterior and posterior liga-
ments.

External lateral (ligamentum collaterale radiale) arises
from external condyle of humerus and is inserted into outer
margin of ulna. Internal lateral (ligamentum collaterale ul-
nare), much stronger, consists of two portions; anterior arises
from fore part of internal condyle to be inserted into coronoid

ARTICULATIONS AXD LIGAMENTS.

Ill

process, and posterior from back part of condyle to inner mar-
gin of olecranon.

Anterior ligament arises above coronoid fossa, and is
inserted into coronoid process of ulna and orbicular ligament.

Posterior ligament, attached above olecranon fossa, and
below to olecranon process of ulna. The anterior and posterior
ligaments become continuous with the lateral to encircle the
joint.

The arteries are derived from superior and inferior pro-

FlG. 64.

1, anterior ligament: 2 and 2, anterior and posterior portions of
internal lateral; 3, orbicular ligament; 4, oblique; 5, interosseous
membrane.

funda. anaatomotiea magna, posterior interosseous recurrent,
anterior and posterior ulnar recurrent and radial recurrent.

The nerves, from median, ulnar, musculocutaneous and
musculospiral.

Tilt; RADIOULNAR ARTICULATIONS (articula I i<i nul ioiilna ris )

are three: the superior, middle and inferior.

The superior radioulnar (articulatio radioulnar^ proxi-
malie) ie a diarthrosis rotatoria, formed by the inner side of
the head of radius and lesser sigmoid cavity of ulna. Its
synovial cavity communicates with the elbow joint, and it is

118 HUMAN ANATOMY.

held together by the orbicular, or annular ligament (ligamen-
tum annulare radii), attached in front and behind to the lesser
sigmoid cavity and surrounding the head of radius. Its arteries
and nerves are the same as for elbow.

The middle radioulnar articulation consists of the oblique,
or round ligament (chorda obliqua), passing from tubercle of
ulna to below tuberosity of radius, and the interosseous (mem-
brana interossea antibrachii) passing between the bones, deficient
above for passage of posterior interosseous vessels, and perfo-
rated below for anterior vessels. Its arteries are from anterior
interosseous ; its nerves, from anterior and posterior interosseous.

Inferior radioulnar (articulatio radioulnaris distal is) con-
sists of anterior and posterior radioulnar ligaments, passing
from one to the other in front and back of wrist, and triangular
interarticular fibrocartilage (discus articularis) , interposed be-
tween head of ulna and cuneiform bone, and binding the radius
and ulna firmly together. Its arteries are from anterior and
posterior interosseous and carpal; its nerves, from median and
posterior interosseous.

The eadiocarpal (articulatio radio car p ea) , or wrist joint,
is a condyloid joint consisting of an elliptical cavity formed by
the radius and triangular cartilage, into which fits the convex
surfaces of the scaphoid, semilunar and cuneiform below. Its
ligaments are external and internal lateral, anterior and pos-
terior radiocarpal.

External lateral (ligamentum collaterale carpi radiate)
passes from the styloid process of radius to the scaphoid, os
magnum and trapezium.

Internal lateral (ligamentum collaterale carpi ulnare)
passes from the styloid process of ulna to the cuneiform, pisi-
form and annular ligament.

The anterior radiocarpal, or volar ligament (ligamentum
radiocarpeum volare), is a broad membrane attached above to
the anterior margin of the radius, its styloid process and ulna,
and below to cuneiform, semilunar, scaphoid and os magnum,
strengthened by a band extending from styloid process of ulna
to semilunar and cuneiform.

The posterior radiocarpal, or dorsal ligament (ligamentum
radiocarpeum dorsale), is attached to dorsal margin of radius,
and below to cuneiform, semilunar and scaphoid. The anterior
and posterior radiocarpal belong to the annular ligament {vide
fascias).

Its arteries are the anterior and posterior carpal, derived

ARTICULATIONS AM) LIGAM KNTS. 119

from the radial and ulnar, anterior and posterior interosseus,
and ascending branches from the deep palmar arch.

Its nerves are derived from the median, ulnar and pos-
terior interosseous.

The carpal articulations (articulatio intercarpea) are ar-
throdial, and consist of three sets. The first row is held together
by two palmar, two dorsal and two interosseous; the second row
by three dorsal, three palmar and three interosseous; and the
two rows are held together by a palmar, dorsal, internal and
external lateral ligament.

First bow. — The palmar, or volar (ligamenta intercarpea
volaria), and dorsal ligaments (ligamenta intercarpea dorsalia),
connect the scaphoid and semilunar, and semilunar and cunei-
form together on the front and back.

The interosseous (ligamenta intercarpea interossea) con-
nect the semilunar with the scaphoid and cuneiform.

The pisiform bone has a separate capsular ligament and an
interosseous ligament connecting it to the fifth metacarpal bone
and cuneiform.

Second Eow. — The palmar (ligamenta intercarpea vol-
aria), and dorsal ligaments (ligamenta intercarpea dorsalia),
connect the trapezium with the trapezoid, and the os magnum
with the trapezoid and unciform, on the front and back of the
wrist.

The interosseus (ligamenta intercarpea interossea) connect
the adjacent surfaces of the trapezium and trapezoid, and the
os magnum with the trapezoid and unciform.

Two Hows Together, — The palmar (ligamenta intercar-
pea volaria) and dorsal (ligamenta intercarpea dorsalia) con-
nect the bones of the first with the second rows on the front and
back of the wrist. The internal lateral passes on the ulnar side
between the cuneiform and unciform. The external lateral,
stronger, passes on the radial side between the scaphoid and
trapezium.

The anterior annular ligament (ligamenlum carpi trans-
versum ) contributes strength to these joints.

The arteries are: Carpal of anterior interosseus, anterior
and posterior carpals of radial and ulnar, carpal of deep palmar
arch, Interosseous recurrent, and terminal branches of anterior
and posterior interosseus.

The nerves are from i linn, ulnar anil posterior inter-

osseus.

Till-; CABFOMETACARPAL ARTICULATIONS (ar/iciihilioiii's car-
pomclticarpea') are each arthrodial joints, held, together by dor-

120 HUMAN ANATOMY.

sal, palmar, interosseous and capsular ligaments, except the
thumb, which has only capsular.

The capsular ligament (capsula articularis) of the thumb
surrounds the margins of the articular surfaces of the first
metacarpal and trapezium, and is lined by a separate synovial
sac.

The palmar, or volar ligaments (ligamenta carpometa-
carpea volaria), and dorsal carpometacarpal (ligamenta carpo-
metacarpea dorsalia) , connect the carpus and metacarpus on
the palmar and dorsal surface.

The interosseus connect the adjoining inferior angles of
os magnum and unciform with the contiguous surfaces, fourth
and fifth metacarpal bones.

The synovial membranes of the wrist consist of five distinct
sacs: First, membrana sacciformis lines lower end of ulna, sig-
moid cavity of radius and upper surface of triangular cartilage;
second, lower surface of radius and cartilage and upper surface
of first row of carpus; third, between margins of carpus and
carpometacarpal joints; fourth, between carpometacarpal joint
of thumb ; and fifth, between pisiform and cuneiform.

Intermetacarpal Articulation. — The bases of the metacarpal
bones, except the thumb, articulate with one another by arthro-
dial joints, lined by synovial membrane continuous with the
carpal sac and connected together by palmar [ligamenta basium
oss. metacarp. volaria), dorsal (ligamenta basium oss. meta-
carp. dorsalia), and interosseous (ligamenta basium oss. meta-
carp. interossea) ligaments. The digital extremities are con-
nected by a transverse ligament (lig amentum capitulorum oss.
metacarpalium transversum) across the anterior surface, con-
tinuous with anterior metacarpophalangeal ligament.

The metacarpophalangeal (articulationes metacarpo-
phalangeal) and phalangeal are of the condyloid variety, like
the wrist joint, allowing of motion in every direction except
laterally. They are each connected by one anterior palmar, or
vaginal ligament (glenoid ligament of Cruveilhier, ligamentum
vaginale), and two lateral, or collateral ligaments (ligamenta
collateralia) , the posterior ligament being substituted by the
extensor tendon, which crosses the dorsum of the joint.

The arteries and nerves are from the digitals.

ARTICULATIONS OF THE LOWER EXTREMITY.

The hip joint (articulatio coxa?) is a true enarthrodial
articulation, formed above by deep cup-like cavity of acetabu-

ARTICULATIONS AND LIGAMENTS. 121

mm, below by prominent spherical head of femur. Its liga-
ments are the capsular, iliofemoral, teres, cotyloid and trans-
verse.

The capsular ligament (capsida articularis) , dense and
strong, is attached above to margin of acetabulum and cot-
yloid ligament, and below to the spiral line in front and to
the neck behind. It is strengthened by several accessory bands,
the pubofemoral (ligamentum pubocapsulare), iliotroehan-
teric, ischiocapsular (ligamentum iscliiocapsulare) , and ilio-
femoral (ligamentum iliofe morale). Of these the latter is the
most important, arising above from anterior inferior spine, and
attached below to spiral line, and has received the name of
Y -ligament of Bigelow.

The ligamentum teres {ligamentum teres femoris), or
round ligament, is a strong triangular band, its base arising
from the bottom of acetabulum and margins of cotyloid notch
externally, its apex inserted below and behind center of head of
femur.

The cotyloid ligament (labrum glenoidale) encircles and
deepens the acetabulum, and at the inner side, under the name
of the transverse ligament (ligamentum transverswm acetabuli),
it bridges over the cotyloid notch, converting it into a foramen
for the passage of nutrient vessels to the joint.

There are numerous bursa about the joint, with one of
which, beneath the iliopsoas muscle, the synovial membrane
often communicates.

Its in levies are derived from the sciatic, internal and exter-
nal circumflex, obturator and gluteal.

Its nerves are derived from the great sciatic, obturator.
accessory obturator and the sacral plexus.

The knee . joint (articulatio genu) is a ginglymoid artic-
ulation, formed above by condyles of femur, below by head of
tibia, and in front by patella.

It- ligaments are divided into two sets, the external, con-
sisting of anterior, posterior, internal lateral, two external
laterals and capsular; and internal, consisting of anterior,
posterior, two semilunar fibrocartilages, transverse, coronary,
ligamentum mucosum and ligaments alaria. Its joint surface
i- the most extensive in the body.

External Set. — Anterior, or ligamentum patella, is the
tendinous portion of extensors of thigh between patella and
tul.enle of tibia. The posterior (ligamentum popliteum obli-

ijiinm). or ligamentum, poslirum Winsloirii, derived principally
from the tendon of semimembranosus, arises from inner tuber-

122 HUMAN ANATOMY.

osity of tibia, passes upward and outward to be inserted into
external condyle of femur.

The internal lateral (ligamentum collaterale tibiale) is a
flat and broad ligament arising from back part of inner condyle
of femur, descends forward to be inserted into inner tuberosity
of tibia, covering in its course the inferior internal articular
artery and nerve, part of tendon of semimembranosus, and
attaching itself to the internal semilunar fibrocartilflge,

The long external lateral ligament (ligamentum collaterale
fibular e), round and strong, arises from tuberosity on outer part
of external condyle, and descends forward to the' head of fibula.
The short external lateral ligament {ligamentum laterale exter-
num breve sen posticum) is an accessory, not very constant,
band, descending posteriorly to the preceding.

The capsular ligament (capsula articularis) fdls up the
intervals between the preceding ligaments, and is strengthened
by bands from fascia lata, vasti, crureus, semimembranosus,
biceps and sartorius tendons.

Internal Set. — Crucial ligaments (ligamenta cruciata genu)
are two strong, short, interosseous, crossing each other from
before backward. The anterior, or external (ligamentum cru-
ciatum anterius), arises from inner posterior part of condyle
of femur, and descends forward and inward to be inserted into
front of spine of tibia and internal semilunar cartilage.

The posterior, or internal (ligamentum cruciatum pos-
terius), arises from outer fore part of inner condyle of femur,
descends downward, backward and outward to spine of tibia.

The semilunar fibro 'cartilages (menisic) consist of two cres-
centic laminae of interarticular cartilage, resting upon the upper
articular surface of tibia, which serve to deepen its surface.

The internal (meniscus medialis) is attached by its inner
border to internal lateral ligament and to head of tibia by
coronary ligaments, its extremities attached in front of anterior
crucial ligament and behind the spine.

The external (meniscus lateralis), more circular, is con-
nected to edge of tibial head by coronary ligaments, its extremi-
ties being inserted behind and in front of the tibial spine.

In other words, the ends of the semilunar cartilages are all,
except the anterior end of internal, attached to the tibia between
the crucial ligaments.

A band of fibers passing from the anterior margin of exter-
nal cartilage to the internal has received the name of transverse
ligament (ligamentum transversum genu).

ARTICULATION AND LIGAMENTS.

123

The knee is lined by the most extensive synovial membrane
in the body, covering both surfaces throughout and extending
up between quadriceps tendon and surface of femur.

Below the patella in front is a duplicative of synovial mem-
brane, inclosing some adipose tissue, which has received the
name of ligamentum mucosum (plica synovialis patellaris) , and
extending from it are two fringes — the ligamenta alaria (plicce
alares).

On either side in the popliteal space behind are bursa?,
which often communicate with the joint.

There are also bursas over the patella?, above and beneath

Fig. 65.

2, anterior crucial ligament; 3,
posterior crucial ligament; 4, trans-
verse ligament; 6, 7, internal and ex-
ternal semilunar cartilages; 8, liga-
menta patellae; 9, bursa patellae; 10,
anterior superior tibiofibular liga-
ment.

Fig. 66.

2, quadriceps extensor; 3, patella;
4, ligamentum patellae; 6. bursa; 7,
8, 9, synovial membrane of knee joint;
10, anterior crucial ligament.

the ligamentum patellae, and between the inner hamstring and
head of tibia.

The arteries of the knee joint are derived from the anasto-
motic magna, the articular branches of the popliteal (five), and
the recurrent branch of the anterior tibial.

[tfl nerves are derived from the anterior crural, obturator,

trial and internal popliteal nerves.

The TIBIOFIBULAR ARTICULATIONS (articulatio tibiofibu~
la/ris) are three— superior, middle ami inferior. The superior
ie an arthrodiai joint between fibular head and outer tuberosity
of tibia, and consists of anterior superior and posterior superior

124 HUMAN ANATOMY.

ligaments1 stretching on either side of the outer tuberosity,
downward and backward, to the head of the fibula. The arteries
are same as the knee; the nerves, from, external popliteal.

The middle consists of an interosseous membrane (mem-
brana interossea cruris) between the bones, connecting- them
firmly together, deficient above, for passage forward of anterior
tibial artery and below for anterior peroneal vessels.

The inferior (syndesmosis tibiofibularis) is an arthrodial
joint between contiguous inferior surfaces of tibia and fibula,
•and consists of four: the interosseus, continuous with that
above; the anterior, inferior tibiofibular (ligamentum malleoli
lateralis anterius), extending downward and outward between
tibia and fibula in front; the posterior inferior tibiofibular (liga-
mentum malleoli lateralis posterius), occupying a similar posi-
tion behind; and the transverse, a long narrow band, passing
between external malleolus and tibia. The synovial membrane
is continuous with that of ankle-joint. The arteries and nerves
are the same as those to the ankle.

The ankle-joint (articulatio talocruralis) is a gingly-
moid articulation, formed between the lower extremity and
malleolus of tibia on the inner side, the malleolus of the fibula
on the outer side, and the astragalus below. Its ligaments are
anterior, posterior, external and internal lateral.

The anterior tibiotarsal ligament (ligamentum talotibiale
anterius) consists of a broad set of irregular fibers, attached
above to lower margin of tibia, below to astragalus. The pos-
terior tibiotarsal ligament (ligamentum talotibiale posterius)
passes transversely between back part of tibia and astragalus.

The internal lateral, or deltoid (ligamentum calcaneotibial
or ligamentum deltoideum), has two layers — the superficial
triangular, its apex arising from malleolus, its base spread out
from before backward to be attached to scaphoid and inferior
calcaneoscaphoid ligament, the sustentaculum, and inner side of
astragalus; and the deep, a short, round cord passing from
internal malleolus to astragalus.

The external lateral ligament (ligamenta talofibularia et
calcaneofibulare) consists of three distinct fasciculi, anterior
(ligamentum talofibular ~e anterius), middle (ligamentum cal-
caneofibidare) , and posterior (ligamentum talofibulare pos-
terius), arising from near summit of external malleolus, and

1 The new anatomical nomenclature (BNA) [inserted through-
out the present edition of this volume] considers the anterior superior
and the posterior superior tibiofibular ligaments as one ligament [liga-
mentum capituli fibulas).

ARTICULATIONS AND LIGAMENTS. 125

being inserted respectively into the front of astragalus, the outer
surface of os calcis, and the back1 of astragalus.

The arteries of the ankle-joint are derived from the malleo-
lar branches of the peroneal and anterior tibial.

Its nerves are branches of the anterior and posterior tibial
nerves.

The articulations of the tarsal bones (articulationes
intertarsece) consist of those of the first row, those of the second
row. and of the two rows with each other.

First Eow. — The astragalus articulates with the calcaneum
by two distinct surfaces separated by the interosseous groove,
and firmly connected by the external (ligament um talocalcaneum
laterale), and posterior (ligamentum talocalcaneum posterius)
calcaneoastragaloid ligaments, and the interosseus (ligamentum
talocalcaneum interossmm) . The external calcaneoastragaloid
ligament passes vertically downward from the outer surface of
astragalus to outer surface of calcaneum. The posterior is a
short, narrow, oblique band connecting the posterior border of
astragalus to the os calcis.

The interosseus (ligamentum talocalcaneum interosseum)
is a strong, short ligament passing vertically and obliquely
downward between the two bones, the principal bond of union.
' The arteries of the first row are tarsal from dorsalis pedis,
external malleolar from anterior tibial, and branches of peroneal
from posterior tibial.

Nerves, from posterior tibial, or plantar.

The second eow is firmly held together by dorsal, plan-
tar and interosseous ligaments. The two former unite the dor-
sal and plantar surfaces and the interosseous, four strong bauds
connect the scaphoid and cuboid (articulatio cubonavicularis) ,
the internal and middle, the middle and external cuneiform,
and the external cuneiform and cuboid.

The arteries of the second row are from plantars and meta-
tarsals. Nerves, from anterior tibial, and internal and external
divisions of posterior tibial nerves.

The two bows of the taesus (articulationes intertarseos)
are connected with each other by three sets of ligaments, first
between os calcis and cuboid, consisting of superior (ligamen-
tum calcaaieocuboideum dorsale) and internal calcaneocuboid
[pars oalcaneocuboidea ligamenti bifurcati), long (ligamentum
plan fare longum) , and short calcaneocuboid (ligamentum cal-
caneocuboid earn plantare) ; second, between os calcis and sca-
phoid, consisting of superior or external, or calcaneonavicular
(pars calcaneonavicularis ligamenti bifurcati), and inferior

126 HUMAN ANATOMY.

calcaneoscaphoid, or internal or calcaneonavicular (ligamentum
calcaneonavicular 'e plantare) ; and third, between astragalus and
scaphoid (artimlatio talonavicularis) , consisting of a single
superior astragaloscaphoid ligament, a band passing from neck
of astragalus to upper surface of scaphoid.

Calcaneocuboid, — The superior (lig amentum calcaneocu-
boideum dorsale) passes between dorsal surfaces of os calcis and
cuboid. The internal (pars calcaneocuboid ea ligamenti bifur-
cati) passing from os calcis to inner side of cuboid, is one of
the main bonds of union between the two rows of tarsus.

The inferior firmly connects the bones below, the lig amen-
tum longce plantce passing from os calcis forward to the plantar
surface of the cuboid, and sending fibers forward to bases of
second, third and fourth metatarsal bones; the lig amentum
breve plantce passing from fore and under surface of os calcis to
under surface of cuboid. The two preceding are important in
preserving the arch of the foot.

The superior and inferior calcaneoscaphoid pass above and
below these bones, firmly connecting them.

The arteries of the mediotarsal joints are derived from the
anterior tibial, tarsal, metatarsal, or external plantar.

Nerves, from external branch of anterior tibial.

The tarsometatarsal articulations (articulationes tar-
sometatarsew) are firmly held together by dorsal (lig amenta
tarsometatarsea dorsalia) and plantar (Kgamenta tarsometa-
tarsea plantaria) ligaments, and connected with one another
by interosseous bands (ligamenta cuneometatarsea interossea),
three in number, passing between internal cuneiform and second
metatarsal bone, external cuneiform and second metatarsal, and
external cuneiform and third metatarsal.

The arteries are from metatarsal, dorsalis pedis, and deep
plantar arch;

The nerves are from anterior tibial and external plantars.

Intermetatarsal Articulations- (articulationes inler-
metatarsew) . — The bases of all except the first are connected
by dorsal (ligamenta basium [oss. metatars.~\ dorsalia), plantar
(ligamentum basium [oss. meiatars.'] plantaria), and the inter-
osseous ligaments (ligamenta basium [oss. metatars.'] interos-'
sea), and the distal extremities are connected by the transverse
metatarsal ligament.

The synovial membranes concerned in these articulations
are six: (1) between the calcaneoastragaloid articulation, pos-
terior to interosseous membrane; (2) anterior calcaneoastraga-

ARTICULATIONS AND LIGAMENTS. 127

loid and astragaloscaphoid ; (3) calcaneocuboid; (-1) between
the middle and the external cuneiform, scaphoid and three cunei-
form, middle and external cuneiform, and second and third
metatarsal, and between the cuboid and the external cuneiform
and the scaphoid ; ( 5 ) between the internal cuneiform and first
metatarsal; and (6) between the cuboid and the fourth and
fifth metatarsal.

The metatarsophalangeal articulations (articula-
tion es metatarsophalangeal) are each connected by two lateral
(ligamcnta collateralia), and a plantar ligament or glenoid
ligaments of Cruveilhier (ligamenta accessoria plantaria) and
the phalangeal articulations are the same, the extensor tendons
acting as dorsal ligaments. They resemble in every respect the
articulations in the hand (vide Hand).

THE MUSCULAR SYSTEM.

The muscles constitute 45 per cent, of the body weight and
are the active agents of locomotion.

They consist of two kinds — -the non-striated or involun-
tary, and the striated, or voluntary. The latter, being usually
under the control of the will (the heart being' a notable excep-
tion), have also received the name of voluntary, and the former,
not under the control of the will, involuntary.

Microscopically, their structure is as follows: —

Non-striated muscular tissue is made up of elongated, con-
tractile, nucleated fiber-cells. They consist of minute fibers in
bundles, inclosed in extremely delicate sheaths of connective
tissue.

They are held together by an albuminous cement and col-
lected by connective tissue into groups or masses one-tenth to
one five-hundredth of an inch in length.

Non-striated muscular tissue is highly vascular and is sup-
plied with nerves from the sympathetic.

Striated muscular tissue is made up of spindle-shaped fibers
of from one and a half to two inches in length and one-two-
hundredth to one-six-hundredth of an inch in diameter. They
are held together in bundles by the endomysium, a delicate fibro-
connective tissue. These bundles are collected into groups by
the perimysium, a stronger connective-tissue band, forming the
fasciculi of the fully formed muscle. Striated muscular tissue
is also highly vascular.

The parts of an individual fiber are — first, the sarcolemma,
a very delicate, transparent, elastic sheath; second, the mem-
branes of Krause, which appear as dark lines stretching across
the fiber at regular intervals, forming the third, or the com-
partments of Krause, which contain the muscular substance.
The latter contain the multinucleated muscle-cells.

The striated muscular fibers of the heart differ somewhat
from the preceding, being branched, and dividing and subdivid-
ing longitudinally to form an intricate network.

The muscles are connected to cartilages, ligaments, bones
and skin, either directly or by aponeuroses or tendons.

(128)

THE MUSCULAR SYSTEM. 129

Aponeuroses are dense, white, fibrous membranes, serving
to connect the muscles with the structures to be acted upon.

Tendons are white, fibrous, glistening! cords. They are
composed of white, fibrous tissue, arranged into bands or
bundles. They are attached to the perichondrium, periosteum,
ligaments and subcutaneous tissue by a mutual interlacement
of fibers.

Classification. — Muscles are classified according to region
of the body, their physiological action, or from their embryo-
logical development. The former arrangement is retained here
for practical purposes.

Names of Muscles. — They have received their names: —

1. From the arrangement of their fibers they are designated
radiated, penniform, bipenniform, etc.

2. From their uses they are called extensors, adductors, etc.

3. From their direction, oblique, rectus, transversalis, etc.

4. From the number of insertions, as triceps, biceps, etc.

5. From their form, as rhomboid, deltoid, etc.

6. From their attachment, as oceipitofrontalis, sternohyoid, etc.

The origin refers to the fixed extremity, or head (caput) ;
the insertion, to the movable point.

Muscles of the Head.

cranial region.

OcciPiTOFitoxTALis (m. epicra nius) . — Origin, by two bel-
lies, one from outer two-thirds of superior curved line of the
occipital bone and base of the mastoid process of the temporal,
the other from corrugator supercilii, orbicularis palpebrarum
and pyramidalis nasi fibers; insertion, into fibrous aponeurosis
covering the vertex of the skull ; action, raises the eyebrows and
used chiefly as a muscle of facial expression; nerves, supraor-
bital, small occipital, facial and posterior auricular branch of
facial.

AURICULAR REGION.

Attollens Aurbm (m. auricularis superior). — Origin, from
aponeurosis of occipitof frontalis \ insertion, into the surface of
the pinna; action, raises the ear; nerve, occipitalis minor.

Attrahens Aurem (m. auricularis anterior). — Origin,
from edge of oceipitofrontalis aponeurosis; insertion, into an-
terior part of helix; action, draws the ear upward and forward;
nerve, facial.

I*i -'i B \ it ia's Aum.nt (ra. auric uh ris posterior). — Origin,
from mastoid portion of temporal bone; insertion, info lower

130 HUMAN ANATOMY.

part of concha; action, draws the ear backward; nerve, posterior
auricular branch of facial.

PALPEBRAL REGION.

Orbicularis Palpebrarum (m. orbicularis- oculi). — Origin,
from nasal process of superior maxilla, internal angular process
of frontal, and from front and sides of tendo palpebrarum;
insertion, into skin of the cheek, eyelids, forehead and temple,
blending with the corrugator supercilii and the occipitofron-
talis; action, sphincter of the eyelids; nerve, facial.

Tendo Palpebrarum (Tendo Oculi), or internal tarsal
ligament (ligamentum palpebrale mediate). — Origin, nasal proc-
ess of superior maxilla ; insertion, inner part of tarsal cartilage.

Corrugator Supercilii. — Origin, superciliary ridge ; inser-
tion, into orbicularis about the middle of the orbital arch;
action, draws eyebrows inward and downward and wrinkles the
forehead; nerve, facial.

Tensor Tarsi, or Horner's muscle (pars lacrimalis of the
orbicularis palpebrarum). — Origin, from crest and orbital sur-
face of lachrymal gland; insertion, into tarsal cartilages near
the puncta lachr}mialia ; action, draws the lachrymal canals
inward and against the globe of the eye; nerve, facial.

ORBITAL REGION.

Levator Palpebr^: Superioris. — Origin, from lesser wing
of the sphenoid, near the optic foramen ; insertion, superior bor-
der of tarsal cartilage; action, elevates the upper eyelid; nerve,
third cranial, or motor oculi.

Pectus Superior (m. rectus superior). — Origin, sheath of
the optic nerve and upper margin of optic foramen; insertion,
into upper surface of sclerotic coat; action, rotates the eyeball
upward ; nerve, third cranial.

Pectus Inferior (m. rectus inferior). — Origin, from lower
and inferior part of optic foramen (ligament of Zinn) ; inser-
tion, into lower surface of sclerotic; action, rotates the eyeball
downward; nerve, third cranial.

Rectus Internus. — Origin, same as rectus inferior; inser-
tion, into inner surface of sclerotic; action, rotates the eyeball
inward; nerve, third cranial.

Pectus Externus (m. rectus lateralis). — Origin, by two
heads — lower from ligament of Zinn and lower margin of
sphenoidal fissure, upper from outer margin of optic foramen;
insertion, into outer surface of sclerotic; nerve, abducens, or

THE MUSCULAE SYSTEM. 131

sixth cranial. Passing between the two heads are the ophthal-
mic vein, the third, nasal branch of fifth, and sixth nerves.

Superior Oblique (m. obliquus superior). — Origin, from
inner margin of optic foramen : its tendon passes through a
pulley near the internal angular process of the frontal bone;
insertion, into sclerotic, between external and superior recti,
midway between entrance of optic nerve and the cornea; action,
rotates the eyeball on its axis; nerve, fourth, or pathetieus.

Inferior Oblique (m. obliquus inferior). — Origin, orbital
plate of superior maxilla ; insertion, near that of superior
oblique, between external and superior recti; action, rotates the
eyeball on its axis; nerve, third cranial.

NASAL REGION.

Pyramidalis Nasi or Procerus. — Origin, from the occipi-
tofrontalis; insertion, into the compressor nasi; action, lowers
the inner angle of the eyebrows ; nerve, facial.

Levator Labii Supebioris Al.eque Xasi. — Origin, nasal
process of superior maxilla; insertion, the ala of the nose and
upper lip. blending with the levator labii oris proprius and
orbicularis ; action, dilates the nostril and elevates the upper
lip; nerve, facial.

Dilator Naris Posterior. — Origin, nasal notch, of su-
perior maxilla; insertion, into skin at the margin of the nostril.

Dilator Naris Anterior. — Origin, from cartilage of the
ala; insertion, into the skin of nose; action, dilates the nostrils;
nerve, facial.

Compressor Nasi. — Origin, superior maxilla, near the
incisive fossa; insertion, into iibrocartilage of the nose, con-
tinuous with the pyramidalis nasi aponeurosis and its fellow;
action, dilates the nostril; nerve, facial.

Compressor Nabium Minor. — Origin,, from alar cartilage;
insertion, into the skin of the end of the nose; action, dilates
the nostril ; nerve, facial.

Depressor Ai.j. Nasi (depressor septi\. — Origin, incisive
fossa of superior maxilla; insertion, into the ala of the nose;
ii'lion. contracts the nostril; nerve, facial.

maxillary region.

Levator Labii Si perIobis (proprius). — Origin, above in-
fraorbital foramen to malar and superior maxilla; insertion,
into the npper lip; action, elevates the upper lip; nerve, facial.

132 HUMAN ANATOMY.

Levator Anguli Oris (m. caninus). — Origin, from canine
fossa; insertion, into the angle of the mouth, blending with the
depressor anguli oris, orbicularis, and zygomatici; action, draws
the angle inward and raises it; nerve, facial.

Zygomaticus Major (m. zygomaticus). — Origin, from
malar bone; insertion, into angle of mouth, blending with
depressor anguli oris and orbicularis.

Zygomaticus Minor. — Origin, from malar bone; inser-
tion, at the angle of the mouth, blending with the levator
superioris; action, draws the lip. outward and upward; nerve,
facial.

Levator Labii Inferioris (m. mentalis). — Origin, from
incisive fossa of lower jaw; insertion, into the skin of the chin;
action, raises the lower lip; nerve, facial.

Depressor Labii Inferioris, or quadratus menti (m.
quadratus labii inferioris). — Origin, from external oblique line
of lower jaw; insertion, into skin of lower lip^ blending with
its fellow and the orbicularis; action, lowers the angle of the
mouth; nerve, facial.

Depressor Anguli Oris, or triangularis menti (m. trian-
gularis).— Origin, external oblique line of lower jaw; insertion,
into the angle of the mouth, continuous with the orbicularis and
risorius at its insertion and the platysma at its origin; action,
depresses the angle of the mouth ; nerve, facial.

Orbicularis Oris. — Origin, by accessory fibers (accessorii
orbicularis superioris and inferioris and nasolabials), from
superior and inferior maxillary borders and nasal septum ; inser-
tion, into the buccinator and adjoining muscles, forming the
sphincter of the mouth ; action, closes the lips ; nerve, facial.

Buccinator. — Origin, from pterygomaxillary ligament and
the posterior alveolar processes of the upper and lower jaw;
insertion, into orbicularis oris; action, compresses and contracts
the cheeks; nerves, facial and buccal branch of the inferior
maxillary nerve.

EisORius (m. risorius) (Santorini). — Otigin, from fascia
of masseter muscle; insertion, at angle of the mouth; action,
draws back the angles of the mouth, — the "smiling" muscle;
nerve, facial.

Masseter: Superficial Portion. — Origin, inner surface
of zygoma and malar process of superior maxilla ; insertion, into
the ramus and angle of the lower jaw.

Deep Portion. — Origin, posterior border and inner sur-
face of the zygoma; insertion, into the ramus and coronoid
processi of the jaw ; action, raises the lower jaw, and the super-

THE MUSCULAR S VST KM. 133

ficial portion assists in drawing it forward; nerve, inferior
maxillary.

Temporal (m. temporalis). — Origin, from the temporal
fascia and the temporal fossa; insertion, into the coronoid
process of the lower jaw; action, raises and draws backward the
lower jaw; nerve, inferior maxillary.

Internal Pterygoid (m. pterygoideus internm). — Origin,
from pterygoid fossa and the tuberosity of the palate-bone;
insertion, into the inner side of the ramus and angle of the
lower jaw; action, draws forward and raises the lower jaw; the
accessory triturating muscle of mastication; nerve, inferior
maxillary.

External Pterygoid (m. pterygoideus externus). — Origin,
by two heads — the lower from the tuberosities of the palate and
superior maxilla and from the external pterygoid plate, the
upper from the pterygoid ridge on the greater wing of the
sphenoid; insertion, into the front of the neck of the lower jaw
and inner side of interarticular cartilage; action, draws the
jaw forward; triturating muscle of mastication; nerve, inferior
maxillary.

Muscles of the Ear (vide Ear).

Muscles of the Neck.

superficial cervical region.

Platysma Myoides (m. platysma). — Origin, from the
deep fascia over the trapezius, deltoid, and pectoral muscles,
and from the clavicle and acromion; insertion, into the lower
jaw and skin of the face; action, wrinkles the skin of the neck
and protects the air-passages and blood-vessels from external
pressure. — rudimentary in man; nerves, branch of superficial
cervical plexus and the facial.

Stei;xocleidomastoid( m. sternocleidomastoideus) . — Origin,
by two heads — sternal portion from the fore and upper part of
the manubrium sterni, the clavicular portion from the inner
third of the upper border of the clavicle, leaving a triangular
interval; msertwrij into t he mastoid process and outer two-
thirds of the superior curved line of the occipital bone; action,
rotates and depresses the head; nerves, spinal accessory and
branches of the cervical plexus.

•

infrahyoid region.

Sternohyoid (m. sternohyoideus) . — Origin, from upper
and back part of the manubrium sterni and inner extremity of

134 HUMAN ANATOMY.

the clavicle; insertion, into the lower border of the os hyoides;
action, depresses the hyoid bone; nerve, branch from the loop of
communication between the deseendens and communicans noni.

Sternothyroid (m. sternothyroideus) . — Origin, posterior
surface of manubrium sterni; insertion, into oblique line of the
surface of the thyroid cartilage; action, depresses the larynx;
nerve, branch from the communicating loop above.

Thyrohyoid (m. tliyreohyoideus) . — Origin, from the ob-
lique line on the surface of the thyroid cartilage ; insertion, into
the greater cornu and body of the hyoid bone; action, elevates
the larynx; nerve,, hypoglossal.

Omohyoid (m. omohyoideus). — Origin, from the upper
border rv£ the scapula and the transverse ligament ; insertion,
into the jwer border of the os hyoides; its center is tendinous
and bound clown to the cartilage of the first rib by a process of
the deep cervical fascia; action, depresses the hyoid bone and
draws it backward; nerve, from the communicating loop above.

SUPRAHYOID REGION.

Digastric (m. digastricus) . — Origin, by two bellies — pos-
terior from digastric groove' of mastoid process of the temporal
bone, anterior from a depression in the lower border of the jaw
near the symphysis; the tendon is held to the hyoid bone by an
aponeurotic loop and pierces the stylohyoid ; action, raises the
tongue and hyoid bone ; nerve, mylohyoid branch of the inferior
dental and facial.

Stylohyoid (m. stylohyoideus) . — Origin, from outer sur-
face of styloid process; insertion, into the body of the hyoid
bone; action, retracts and elevates the hyoid bone; nerve, facial:
near its insertion it is perforated by the tendon of the digastric.

Mylohyoid (m. mylohyoideus) .—Origin, from the mylo-
hyoid ridge of the inferior maxilla from last molar to sym-
physis; insertion, into a fibrous raphe in the median line,
extending from the hjroid bone to the chin and into the body
of the hyoid bone ; action, draws forward and elevates the hyoid.
bone and forms part of the floor of the mouth ; nerve, mylohyoid
branch of the inferior dental.

Geniohyoid (ra. genioliyoideus). — Origin, from inferior
genial tubercle of the internal surface of the symphysis of the
jaw; insertion, into the front of the body of the hyoid bone;
action, same as the mylohyoid; nerve], hypoglossal.

THE MUSCULAR SYSTEM. I35

MUSCLES OF THE TONGUE.

GtENIOHYOglossus (111. genioglossus) . — Origin, from supe-
rior genial tubercle of the internal surface of the symphysis of
the jaw: insertion, by fanlike expansion into the whole length
of the inferior surface of the tongue, the side of the pharynx,
and the body of the hyoid bone; action, retracts and protrudes
the tongue; nerve, the hypoglossal.

Hyoglossus (111. hyoglossus). — Origin, body and greater
corrni of the hyoid bone; insertion, between the lingualis and
styloglossus into the side of the tongue; action, renders the
tongue convex from side to side; nerve, hypoglossal.

Styloglossus (m. styloglossus). — Origin, from stylomax-
illary ligament and styloid process of tbe temporal ; m< lertion,
into the side of- the tongue, blending with the hyogii sSus and
lingualis; action, retracts and elevates the tongue; nerve, hypo-
glossal.

Lixgualis. — Consists of four portions: superior lingualis
(in. longitudinal is superior), very superficial from base to apex,
just beneath the mucosa of the dorsum; inferior lingualis (m.
iuiiijitudinalis inferior), two muscle-bands from base to apex
on inferior surface; transversa ''n'gualis (m. transversus lin-
gua), and the vertical lingualis („ . verticeuis Imgum), as indi-
cated by their names, send transverse fibers between the superior
and inferior muscles, the latter sending muscle-fibers from dor-
sum to mucosa and interlacing with the other muscles. Action,
renders the tongue convex from before backward'; nerve, the
chorda tympani.

Palatoglossus (Constrictor [sthmi Faucium).
Vide Palatal Region.

PHARYNGEAL AND PALATAL REGION.

I !ons 1 htctor Superior (m. constrictor pharyngis superior).
— Origin, from margin of internal pterygoid plate and its
hamulai process; from pterygomaxillary ligament, part of the
alveolar process of the lower jaw and side of the tongue, tendon
of the tensor palati, and part of the palate bone; insertion, into
the median raphe and the pharyngeal spine of the basilar process
of the occipital hone; action, constricts the pharynx; nerves,
pharyngeal plexus and glossopharyngeal.

Constrictor Medius (m. constrictor pharyngis medius).
Origin, from the stylohyoid ligament, greater and Lesser cor-
ona of the hyoid hone; insertion, into the median fibrous raphe,

136 HUMAN ANATOMY.

blending with its fellow of opposite side; action, constricts the
pharynx; nerves, pharyngeal plexus and glossopharyngeal.

Constrictor Inferior (m.. constrictor pharyngis inferior).
— Origin^, from the sides of the thyroid and cricoid cartilages;
insertion, into the fibrous raphe of the pharynx; action, con-
tracts the pharyngeal canal; nerves, external laryngeal, glosso-
pharyngeal plexus.

Stylopharyngbus (m. stylopharyngeus) . — Origin, from
base of the styloid process; insertion, into the constrictor mus-
cles, palatopharyngeus, and posterior border of the thyroid
cartilage ; nerves, pharyngeal plexus and glossopharyngeal.

Levator Palati (m. levator veli palatini). — Origin, carti-
laginous portion of Eustachian tube and apex of the petrous
portion of the temporal bone; insertion, into the back part of
the soft palate, blending with its fellow of the opposite side;
action, elevates the soft palate ; nerve, descending palatine from
Meckel's ganglion, from the facial.

Tensor Palati, or Circumflexus (m. tensor veli pala-
tini).— Origin, from spine of the sphenoid, vaginal portion of
temporal bone, cartilage of Eustachian tube, and scaphoid fossa
at base of internal pterygoid plate; insertion, into the palate
bone and the soft palate; action, renders tense the palate; nerve,
a branch from the otic ganglion.

Azygos Uvulae (m. uvulce). — Origin, from aponeurosis of
soft palate and posterior nasal spine; insertion, into the uvula;
action, raises the palate; nerves, descending palatine branches
and Meckel's ganglion, from the facial.

Palatoglossus (m. glossopalatinus) — Constrictor Isth-
mi Faucium). — Origin, from soft palate on either side of
the uvula; insertion, into the dorsum and side of the tongue,
blending with the fibers of the styloglossus — this muscle forms
the anterior pillar of the fauces; action, constricts the fauces;
nerves, palatine branches of Meckel's ganglion.

Palatopharyngeus (m. pliaryngopalatinus). — Origin, by
two portions, from soft palate; insertion, into posterior border
of thyroid cartilage and pharynx; this muscle forms the pos-
terior pillar of the fauces; action, closes the posterior nares;
nerves, palatine branches from Meckel's ganglion.

VERTEBRAL REGION.

Pectus Capitis Anticus Major. — Origin, by four ten-
dons from transverse processes of the third, fourth, fifth and
sixth cervical vertebrae; insertion, basilar process of occipital

THE MUSCULAK SYSTEM. 137

bone; action, flexes the head; nerves, suboccipital and deep
internal branches of cervical plexus.

Rectus Capitis Anticus Minoe. — Origin, from root of
transverse process and anterior part of the lateral mass of the
atlas; insertion, basilar process of occipital, behind the former;
action, flexes the head; nerves, suboccipital and deep branches
of the cervical plexus.

Rectus Lateralis. — Origin, superior surface of the trans-
verse process of the atlas; insertion, inferior surface of the jugu-
lar process of the occipital; action, draws the head laterally;
nerves, suboccipital and deep internal branches of the cervical
plexus.

Longus Colli. — Origin, from three portions, superior ob-
lique portion from anterior tubercles of the transverse processes
of the third, fourth and fifth cervical ; insertion, tubercle on
the anterior arch of atlas ; inferior oblique portion, origin, from
anterior surface of the bodies of the first two or three dorsal
vertebras; insertion], anterior tubercles of the transverse proc-
- - of the fifth and sixth cervical; vertical portion, origin,
from the anterior surface of the bodies of the lower three
cervical and upper three dorsal bodies of the second, third and
fourth cervical vertebras; action, rotates and flexes the cervical
portion of the vertebrae; nerves, anterior branches of the lower
cervical nerve.

Scalenus Anticus (m. scalenus anterior). — Origin, from
the tubercle of the first rib; insertion, into the anterior tuber-
cles of the transverse processes of the third, fourth, fifth and
sixth cervical vertebrae; action, flexes and rotates the vertebral
column; nerves, anterior branches of the lower cervical nerve.

Scalenus Medius. — Origin, upper surface of the first rib,
behind the groove for the subclavian artery; insertion^ into the
transverse processes of the lower six cervical vertebrae; action,
rotates ami flexes the vertebral column; nerves, the anterior
branches of the lower cervical nerve: the posterior thoracic,
long thoracic nerve, or external respiratory nerve of Bell, has
itfl origin in the substance of this muscle, by union of two roots
from fifth and sixth cervical nerves.

x LLENU8 Posticus (m. scalenus posterior) . — Origin, from
the outer Burface of the second rib, behind the serratus magnus;
insertion, into the posterior tubercles of the transverse processes

of the lower two or three cervical vertebrae; ad inn. Ilexes and
rotates the -pine; nerves, anterior branches of the lower cervical
nerves.

138 HUMAN ANATOMY.

Of these muscles the scalenus medius is the longest and
largest, and the scalenus posticus the smallest.

Muscles of the Larynx and Epiglottis (vide Larynx).

Muscles of the Trunk.

muscles of the back.

First Layer.

Trapezius. — Origin, from inner third of superior curved
line of the occipital bone, the ligamentum nucha?, the spinous
processes of the seventh cervical, and all the dorsal vertebrae;
insertion, into the outer third of the posterior border of the
clavicle, the inner margin of the acromion process, and the
crest of the spine of the scapula ; action, with head fixed elevates
point of shoulder, with shoulders fixed together draws head
backward, or singly draws head to corresponding side; adducts,
rotates inward and depresses humerus; nerves, cervical plexus
and spinal accessory.

Ligamentum Nuchze. — Origin, from external occipital
protuberance; insertion, spinous processes of the cervical verte-
brae, from the second to the seventh. This ligament is rudi-
mental in man, and in the lower animals sustains the head.

Latissimus Dorsi. — Origin, by an aponeurosis from the
spinous processes of the six lower dorsal, the lumbar and sacral
vertebrae, the supraspinous ligament, the crest of the ilium, and
the three or four lower ribs; insertion, into the inner lip of the
bicipital groove of the humerus, in front of the teres major, and
a little above the pectoralis major; the tendon of this muscle
twists completely on itself, so that the superior fibers become
the inferior ; action, draws the arm backward and downward, or,
fixing the arm, raises the lower ribs and draws the trunk for-
ward; nerve, subscapular.

Second Layer.

Levator Anguli Scapulae (m. levator scapulce). — Origin,
from three to five tendons from the posterior tubercles of the
transverse processes of the three or five upper cervical vertebrae ;
insertion, into posterior border of the scapula, at the root of the
spine; action, elevates the angle of the scapula; nerve, anterior
division of the third and! fourth cervical nerves.

Ehomboideus Minor. — Origin, from spinous processes of
seventh cervical and first dorsal vertebrae and the ligamentum
nuchas; insertion, into root of the spine of the scapula; action,

THE MUSCULAE SYSTEM.

139

draws the inferior angle upward and backward; nerves, branches
from the fifth cervical nerve.

Rhomboidbus Major. — Origin, from supraspinous liga-
ment and spinous processes of four or five upper dorsal verte-
brae; insert wn. by a tendinous arch attached above near the

Fig. 67.

Muscle3 of the back: 1, trapezius; 2, 4, latissimus dorsi; 10. leva-
tor anguli scapulae; 11, rhomboioVus minor; 12. rhomboideus major;
13, 14, splenius capitis et colli; 15, vertebral aponeurosis; 1G, serratus
posticus inferior.

-pine and below to the inferior angle of the scapula: action,
draw- the inb-rior angle upward and backward; nerves^ branches
i.f the fifth cervical.

Third Layer.

Serrati - Postk i a Supebiob (//'. serratus posterior supe-
rior). Orujiii. from spinous processes of the two or three upper

140 HUMAN ANATOMY.

dorsal and last cervical vertebras, and from the ligamentum
nuchas; insertion, into upper borders of the second to the fifth
ribs inclusive; action, assists in respiration; nerves, external
branches of' the posterior division of the cervical.

Serratus Posticus Inferior (m. serratus posterior infe-
rior) .—Origin, from spinous processes and interspinous liga-
ments of two or three upper lumbar and two lower dorsal
vertebrae; insertion, into lower borders of the four lower ribs,
external to their angles; action, elevates the ribs; assists in
respiration; nerves, external branches of the posterior divisions
of the lower dorsal.

Splenius. — Origin, from spinous processes of last cervical
and six upper dorsal vertebra?, the lower half of the ligamentum
nuchas, and the supraspinous ligament ; insertion, by two heads —
splenius capitis (m. splenius capitis) into the occipital bone,
just below the superior curved line and the mastoid process of
the temporal bone; splenius colli (m. splenius cervicis) into pos-
terior tubercles of the transverse processes of the three or four
upper cervical vertebras; action, separately, rotates the head and
draws it to the other side; together, draw the head back-
ward; nerves, external branches of the posterior divisions of the
cervical.

Fourth Layer.

Erector Spin^e (m. sacrospinalis) . — Origin, from sacro-
iliac, groove and from a broad tendon attached internally to the
spinous processes of the lumbar and two or three lower dorsal
vertebrae and supraspinous ligament; externally, the crest of the
ilium and the posterior part of the sacrum; insertion, by two
parts — (1) sacrolumbalis or iliocostalis (m. iliocostalis lum-
borum), inserted into the angles of the six or seven lower ribs;
this muscle has two accessory portions (a) musculus acces-
sorius ad iliocostalem (m. iliocostalis dorsi) : origin, from
angle of six lower ribs; insertion, angles of six upper ribs;
(&) cervicalis ascendens: origin, angles of the four or five
upper ribs ; insertion, into the posterior tubercles of the fourth
to the sixth cervical vertebras, inclusive; (2) longissimus dorsi;
insertion, into the transverse processes of all the dorsal vertebras,
and from the seventh to the eleventh ribs, inclusive, between
their angles and tubercles; action, bends the trunk backward
and erects the spine; nerves, external branches of the posterior
divisions of the lumbar and dorsal.

TplAnsversalis Colli, or cervicis (m. longissimus cervi-
cis).— Origin, transverse processes of six upper dorsal vertebras;

THE MUT3CULAK SYSTEM. 141

insertion:, into the posterior tubercles of the transverse proc-
esses of the second to the sixth cervical vertebra? inclusive;
nerves, external branches of the posterior divisions of the
cervical.

Trachelomastoid (m. longissimus capitis). — Origin, from
articular processes of three or four lower cervical, and from the
transverse processes of the third to the sixth dorsal vertebrae;
insertion, into the posterior margin of the mastoid process, below
the sternomastoid and the splenitis; action, steadies the head;
nerves, external branches of the posterior divisions of the
cervical.

Spinalis Dorsi. — Origin, spinous processes of last two
dorsal and first two lumbar vertebrae; insertion; into spinous
processes of the dorsal vertebrae, blending with the semispinalis
dorsi; action, erects the spinal column; nerves, external branches
of the posterior divisions of the cervical.

Spinalis Cervicis, or spinalis colli (to. spinalis cervicis).
— Origin, from the spinous processes of the fifth to the seventh
cervical vertebrae ; insertion, into the spinous process of the axis ;
action, steadies the neck; nerves, same as above; this muscle is
absent in 20 per cent, of the subjects.

Com plexus or Semispinalis Capitis (to. semispinalis
capitis). — Origin, by seven tendons from transverse processes
of the upper three dorsal and seventh cervical and articular
processes of the fourth, fifth and sixth cervical; insertion, into
the occipital bone, between the curved lines; action, separately,
rotates and draws the head to one side; together, draw the head
directly backward; nerves, suboccipital, great occipital, and in-
ternal branches of the posterior divisions of the cervical.

Fifth Layer.

Semisi'Inales Dorsi. — Origin, from transverse processes
from the fifth to eleventh dorsal vertebra1; insertion, into the
spinous processes of the lower two cervical and upper four dor-
saJ vertebrae; action, erects the spinal column; nerves, internal
branches of the posterior divisions of the cervical.

Semispinalis Ceevicts, oe Colli (to. semispinalis cervir
ris). — Origin, from transverse processes of lower four cervical
and upper four dorsal vertebrae; insertion, into spinous proc-
esses of the -••■oiid to the fifth cervical vertebra?; action, erects
the spinal column; nerves, same as above.

.Mi I/mini s Si-in.k (m. mvltifidus) . — Origin, from the
transverse processes in the dorsal region, the articular. processes

142 HUMAN ANATOMY.

ill the cervical and lumbar region, the posterior superior spine of
the ilium, posterior sacroiliac ligaments, and from the aponeu-
rotic arch of the erector spinas; insertion, each fasciculus is
attached to the laminae and spinous process of the vertebras above ;
action, preserves the erect condition of the spine ; nerves, internal
branches of the posterior divisions of the cervical, dorsal, lum-
bar and sacral nerves,

Botatores Spiislze (mm. rotatores). — Eleven on either side.
Origin, from upper part of transverse process; insertion, into
outer surface and lower border of the laminae of the vertebrae
above, from, the first and second dorsal to the eleventh and
twelfth; action, rotates the spinal column; nerves, anterior
branches of the posterior divisions of the dorsal.

Supraspinales. — Origin and insertion, the spinous proc-
esses in the cervical region of the vertebrae; action, extends
cervical spine; nerves, internal branches of the posterior divi-
sions of the cervical.

Interspinales. — Consist of muscular bands in pairs be-
tween the spinous processes of the adjoining vertebrae : six pairs
in the cervical region, three pairs in the dorsal, four or five' in
the lumbar; action, extend the spine; nerves, internal branches
of the posterior divisions of the cervical dorsal and lumbar.

Extensor Coccygis. — Origin, from the first piece of the
coccyx, or last bone of the sacrum; insertion, into the lower
extremity of the coccyx; action, rudimental in man.

Intertransversales (mm. intertransversarii) . — Are small,
muscular bands between the transverse processes : in the cer-
vical regiom seven pairs, in the dorsal twelve pairs, in the lum-
bar region four pairs; action, flex the spine laterally; nerves,
internal branches of the posterior division of the cervical, dor-
sal and lumbar.

Bectus Capitis Posticus Major (m. rectus capitis pos-
terior major). — Origin, from the spinous process of the axis;
insertion, into inferior curved line of the occipital bone; action,
rotates the atlas and the cranium ; nerve, the suboccipital.

Bectus Capitis Posticus Minor (m. rectus capitis pos-
terior minor). — Origin, from the tubercle of the posterior arch
of the atlas; insertion, below the inferior curved line of the
occipital bone; action, draws the head backward; nerve, sub-
occipital.

Obliquus Capitis Inferior.- — Origin, spinous process of
the axis; insertion, lower back portion of the transverse process
of the atlas; action, rotates the atlas and the cranium; nerves,
suboccipital and great occipital.

THE MUSCULAR SYSTEM. 143

Obliquus Capitis Superior. — From upper surface of the
transverse process of the atlas; insert ion, between the curved
lines of the occipital bone to the outer side of the complex us ;
action, rotates the atlas; nerves, suboccipital and great occipital.

MUSCLES OF THE ABDOMINOTHORACIC REGION.

Obliquus Externus {m. obliquus externus abdominis).' —
Origin, lower borders of the eight lower ribs; insertion, the
lowermost muscular fibers, into the anterior half of the iliac
crest ; the other muscular fibers, by a broad aponeurosis, which
joins the anterior half of the aponeurosis of the internal oblique
to form the anterior walls of the sheath of the rectus, above
into the ensiform cartilage, below into the symphysis pubis. In
the median line it blends with its fellow of the opposite side to
form the linea alba. A slit in its lower portion above the pubic
spine is called the external abdominal ring. The lower, thick-
ened portion of the aponeurosis stretching between the anterior
superior iliac spine and the pubic spine is called Poupart's liga-
ment, or the ligament of Fallopius. A reflection from it to the
iliopectineal line is called Gimbernat's ligament; action, flexes
the pelvis on the thorax, or vice versa, and compresses the
viscera : nerves, lower intercostal, iliohypogastric and ilioin-
guinal.

Obliquus Internus, or internal or ascending oblique (m.
obliquus internus abdominis). — Origin, from the outer half of
Poupart's ligament, from the anterior two-thirds of the crest
of the ilium, and the posterior lamellae of the lumbar fascia;
insertion, above to the lower four costal cartilages, below, con-
jointly with the tendon of the transversalis, into the os pubis
ami linea il iopeei inea, to form the conjoined tendon | the outer
portion of this tendon being termed the ligament of Ilesselbach
(ligamentum interfoveolare; the inner part, the ligament of
Benle], and into the median line (linea alba) by an aponeurosis
e tending from the sternum and seventh and eighth costal carti-
iu the pubis. This aponeurosis at its lower fourth consists
of two united lamina' passing in front of the rectus muscle, but
in its upper three-fourths M. divides, one lamina passing in front
of the rectus and joining the aponeurosis of the externa! oblique,
ther passing behind and joining the aponeurosis of the
transversalis; action, same as the externus; nerves, same as
externus.

Transversalis (m. fransversus abdominis) . Origm, from
outer third of Poupart's hgamenl and anterior three-fourths of

144

HUMAN ANATOMY.

the crest of the ilium, from the inner surface of the cartilages
of the six lower ribs, and from the spinous and transverse proc-
esses of the lumbar vertebras ; insertion, by the conjoined tendon
into the linea iliopectinea and crest of the os pubis; action and
nerves, same as the externus.

Fig. 68.

Muscles of abdomen: 12, external oblique; 16, rectus abdominis; 18,
internal oblique; 17, pyramidalis; 19, quadratus lumborum.

Rectus Abdominis. — Origin, by two tendons — the outer
from the crest of the pubis, the inner interlacing with its fellow
of the opposite side; insertion, into the cartilages of the fifth,
sixth and seventh ribs; action, depresses the thorax, flexes the
vertebral column, and, acting from above, flexes the pelvis upon
the vertebral column.

Pyramidalis. — Origin, from the os pubis and anterior
pubic ligament; insertion, into the linea alba, midway between
the os pubis and umbilicus.

THE MUSCULAR SYSTEM.

145

Quadratus Lumboeum. — Origin, by two portions — pos-
terior portion, from crest of the ilium and iliolumbar ligament ;
insertion, into lower border of the last rib and transverse proc-
esses of the three lower lumbar vertebrae; origin, anterior por-
tion, from upper border of the transverse processes of the
lumbar vertebra?, from the third to the fifth; insertion, into
one-half the lower margin of the last rib and apices of upper
four lumbar vertebras; action, draws down and fixes the last rib
and assists in inspiration and expiration.

Fig. 69.

Diaphragm: 1, 2, 3, central eordiform tendon; 4, middle leaflet;
5, ligamentum arcuatum externum; 6, ligamentum arcuatum inter-
num; 8, right crus; 10, left crus; 11, aortic opening; 12, esophageal
opening; 13, opening for vena cava; 14, psoas magnus; 15, quadratus
lumborum.

MUSCLES OF THE THORAX.

[ntebcostales Externi (mm. intercostales externi). —

Eleven pair- ou either side. Origin, from the outer bonier of
roove on the lower border of each rib, from the cartilage
to the tubercle; insertion, into upper border of the rib below;
nit ion, rai-es the ribs; nerve, intercostal.

[ntercostales Ixtkum (mm. intercostales interni). —
Origin, inner lip of the groove on the lower border of each rib;
insert ion, into tbe upper border of the rib below; action, pulls

the ribs upward; nerve, intercostal.

10

146 HUMAN ANATOMY.

Infracostales — Subcostales (mm. subcostales). — Origin,
inner surface of rib ; insertion, into the inner surface, from the
first to the third rib below; action, inspiratory muscles; nerve,
intercostal.

Triangularis Sterni (m. transversus thoracis). — Origin,
lower part of the back of the sternum and back of ensiform
cartilage and inner surface of sternal end of the costal cartilages
of the three or four lower ribs; insertion, into the border and
inner surfaces of the costal cartilages, from the second to the
sixth rib inclusive (it is continuous below with transversalis
abdominis muscle); action, draws down the costal cartilages;
nerve, intercostal.

Levatores Costarum. — Twelve on either side. Origin,
from transverse processes of seventh cervical and eleven upper
dorsal vertebrae; insertion, into upper surface of the rib below,
between the angle and tubercle; action, raises the ribs; nerve,
the intercostal.

diaphragmatic region.

Diaphragm (diapkragma) . — Origin, inner surface of ensi-
form cartilage, cartilages and bony portions of six or seven lower
ribs in front, and from two aponeurotic arches, the ligamentum
arcuatum externum (arcus lumbocostalis lateralis) and inter-
num (arcus lumbocostalis medialis) , and the lumbar vertebra?
behind (pars lumbalis) ; insertion, into the circumference of
the central or cordiform tendon (centrum tendineum) ; action,
the principal muscle of inspiration and expulsion; nerves, the
phrenic, and phrenic plexus of the sympathetic.

the openings in the diaphragm.

The aortic opening is placed posteriorly between the two
crura, in front of the spine. It transmits the aorta, thoracic
duct, and vena azygos major, and sometimes the left sympa-
thetic nerve.

The esopliageal opening is in front of the decussation of
the crura, a little to the left and in front of the aortic opening
(hiatus aorticus) . It transmits the esophagus and pneumogas-
tric nerves.

The foramen quadratum, or opening (foramen vena cava})
for the vena cava., is placed at the highest part of the central
tendon, a little to the right. It transmits the vena cava and
maintains its jpatencx. The cms on each side transmits the
sympathetic and greater and lesser splanchnic nerves, and in
addition the left transmits the vena azygos minor,

THE MUSCULAK SYSTEM. U*

Muscles of the Perineum (vide Perineum).

Muscles of the Upper Extremity.

muscles of the shoulder.

Pectoralis Major. — Origin, from the sternal half of the
clavicle (clavicular portion) and anterior surface of the sternum
and costal cartilages from the second to the sixth or seventh
rib (sternocostal portion) ; insertion, into the anterior bicipital
ridge of the humerus; action, draws the arm across the chest;
nerves, external and internal anterior thoracic.

Pectoralis Minor. — Origin, upper and outer surface of
the third to the fifth rib, inclusive, and the aponeurosis of the
intercostal muscles; insertion, into anterior border of the cor-
acoid process of the scapula; action, draws the scapula inward
and downward; nerve, the anterior thoracic.

Subclavius. — Origin, from cartilage of the first rib ; inser-
tion, under surface of the clavicle, about its middle third ;
action, depresses the shoulder, and draws clavicle forward and
downward; nerve, branch from the union of the fifth and sixth
cervical.

Serratus Magnus (to. serratus anterior). — Origin, by
nine muscular portions, from the outer surface of the eight
upper ribs (two divisions being from the second rib) and from
the upper intercostal aponeurosis; insertion, by three divisions —
upper portion into superior angle of the scapula, middle portion
into posterior portion of the scapula between the inferior and
superior angles, lower portion into the inferior angle of the
scapula; action, raises the vertebral bonier and carries the
scapula forward; nerve, the posterior thoracic.

Deltoid (to. deltoideus). — Origin, from the outer third of
the clavicle and from the outer part of the acromion process and
the lower border of the scapular spine; insertion, into the outer
side of the -luit't of the humerus, about its middle into the del-
toid tubercle; action, raise- the arm; nerve, the circumflex.

Si BSCAJP1 LABIS. — Origin, from the internal two-thirds of
the subscapular fossa; insertion, into the lesser tuberosity of the
humerus; at lion, rotates the bead of the humerus inward;
nerves, upper and lower subscapular.

Supraspinatus. — Origin, from inner two-thirds of supra-
spinous fossa; insertion, into the uppermost facet of the greal
tuberosity of the humerus; action, assists in raising the arm
and fixing the head of the humerus; nerve, the suprascapular.

148 HUMAN ANATOMY.

Infraspinatus. — Origin, from the inner two-thirds of the
infraspinous fossa; insertion, into the middle facet of the great
tuberosity; action, rotates the head of the humerus outward;
nerve, suprascapular.

Teres Minor. — Origin, posterior surface of the upper two-
thirds of the axillary border of the scapula ; insertion, into the
lowest facet of the great tuberosity; action, rotates the head of
the humerus outward; nerve, the circumflex.

Teres Major. — Origin, posterior surface of the inferior
angle of the scapula ; insertion, into the posterior bicipital ridge
of the humerus ; action, draws the humerus backward and down-
ward, assisting the latissimus dorsi; nerve, the lower sub-
scapular.

HUMERAL REGION

CoRACOBRAcniALis. — Origin, from apex of the coracoid
process of the scapula; insertion, into the inner side of the
middle of the shaft of the humerus, between the origin of the
brachialis anticus and short humeral head of the triceps ; action,
draws the humerus inward and forward; nerves, the musculo-
cutaneous and a branch of the musculospiral.

Biceps — Flexor Cubiti (to. biceps bracliii). — Origin, by
two heads; short head from the apex of the coracoid process,
along with the coracobrachialis ; the long (glenoid) head {caput
longum) from the upper margin of the glenoid cavity of the
scapula; insertion, into the posterior part of the tuberosity of
the radius; action, flexes the forearm; nerve, the musculocu-
> ianeous.

Brachialis Anticus (to. brachialis) . — Origin, inner and
outer surfaces of the shaft of the humerus, embracing the inser-
tion of the deltoid; insertion, into the anterior surface of the
coronoid process of the ulna; action, flexes the forearm; nerve,
\ the musculocutaneous.

Triceps — Extensor Cubiti (to. triceps bracliii). — Origin,
r by three heads — middle, or scapular head (caput longum), below
the glenoid cavity of the scapula; external head (caput laterale),
from the posterior aspect of the shaft of the humerus, between
the upper part of the musculospiral groove and the insertion of
the teres minor, and from the external intermuscular septum ;
the internal head (caput, mediale), from the posterior aspect of
the shaft of the humerus, below the insertion of the teres major,
and below the groove for the musculospiral nerve; insertion, by
a common head, into the posterior part of the under surface of

THE MUSCULAR SYSTEM.

14D

the olecranon process of the ulna; action, extends the forearm;
nerve, the musculospiral.

Subanconeus (m. anconceus) . — Origin, from the posterior
surface of the humerus, above the olecranon fossa; insertion,
into the posterior ligament of the elbow-joint; action, draws up
the posterior ligament of the elbow-joint during extension of
the forearm; nerve, the muscnlospiral.

Fig. 70.

Muscles of shoulder and arm; 4,
subscapulars; 5, teres major; G,
coracobrachial is; 7, biceps.

Fig. 71.

Triceps muscle: 1, external head;
2, scapular head; 3, internal head;
4, insertion.

MUSCLES OF THE FOREARM.

Anterior Superficial Layer.

Phonatob Radii Teres (w. /initiator tens). — Origin, by
two heads — the smaller from the coronoid process of the ulna,
the ulnar head {caput ulnare), the larger from the humerus,
the internal condyle, the humeral head (caput numerate),
and from the common tendon of this group of muscles, and
intermuscular Beptum; insertion, into the outer aspeel of the

150

HUMAN ANATOMY.

shaft of the radius; action, pronates the hand; nerve, the
median.

"Flexor Carpi Radialis. — Origin, by the common tendon
from the inner condyle, and from the intermuscular septum
between it and the pronator teres; insertion, into the base of
the metacarpal bone of the index finger ; action, flexes the wrist ;
nerve, the median.

Fig. 72.

Muscles of forearm: 1, biceps; 2, brachialis anticus;
supinator longus; 5, extensor carpi radialis longior; 6,
radialis brevior; 8, extensor communis digitorum; 12,
ulnaris; 13, 14, extensors of thumb.

3, triceps ; 4,
extensor carpi
extensor carpi

Palmaris Longus. — Origin, from the inner condyle of the
humerus by the common tendon and the intermuscular septum
and the deep fascia; insertion, into the annular ligament,
spreading out in the palmar fascia; action, renders tense the
palmar fascia; nerve, the median.

Till: MUSCULAR SYSTEM. i;,l

Fuexob Caepi Ulnabis. — Origin, by two heads — one by
the common tendon from the inner condyle of the humerus, the
other from the inner margin of the olecranon, the intermuscular
septum, between the ulna and the flexor suhlimis digitorum, and
from the upper two-thirds of the posterior aspect of the ulna;
insertion^, pisiform hone; action, flexes the wrist; nerve, the
ulnar.

Flexor Sublimis Digitorum — Perforates (m. flexor
digitorum sublimis). — Origin, by three heads — one from the
coronoid process of the ulna, the ulnar head (caput vlnare),
above the pronator radii teres, another from the common tendon
from the internal condyle of the humerus, the humeral head
(caput humerale), and the third, the radial head (caput radiale)
from the oblique line of the radius, from the insertion of the
pronator radii teres, to the tubercle; each tendon divides at the
base of the first phalanges (chiasma tendinum) to allow the
passage of the tendon of the flexor profundus digitorum; inser-
tion, into the lateral margins of the second phalanges by four
tendons; action, flexes the second phalanges; nerve, median.

Anterior Veep Layer.

Flexor Profundus Digitorum — Perforaxs (m. flexor
digitorum profundus). — Origin, from the inner side of the
coronoid process, and from the upper two-thirds of the front
ami inner aspect of the shaft of the ulna, between the brachialis
anticus above and the pronator quadratus below; insertion, by
four tendons into the bases of the last phalanges, perforating
the tendons of the flexor sublimis; action. Hexes the phalanges;
nerves, the anterior interosseous and the ulnar.

Plexob Longus Pollicis (»'. flexor pollicis longus). —
Origin, from the upper two-thirds of the shaft of the radius and
from tin' interosseous membrane; insertion, into the base of the
last phalanx of the thumb; action, ilexes the phalanges; nerve,
the anterior interosseous.

Pronator Quadbatus. — Origin, anterior border of the
ulna and from the oblique line of the lower fourth of the
anterior aspeci of the ulna; insert inn , into the lower fourth of
the front and outer border of the shaft of the radius; action,
pronates the hand ; nerve, anterior interosseous.

Radial Region,

- pii ltob Lovers (in. Iivaeliinniiliiitis) . Origin, from
the upper two-thirds of the external condyloid ridge of the

152 HUMAN ANATOMY.

humerus and the external intermuscular septum; insertion, into
the base of the styloid process of the radius; action, supinates
the hand ; nerve, musculospiral.

Extensor Carpi Eadialis Longior (m. extensor carpi
radialis long us). — Origin, from the lower third of the external
condyloid ridge of the humerus, from the common tendon of
the extensor muscles of the forearm from the external condyle,
and the intermuscular septum; insertion, into the radial side of
the base of the metacarpal bone of the index finger; action,
extends the wrist; nerve, musculospiral.

Extensor Carpi Eadialis Brevior (m. extensor carpi
radialis brevis). — Origin, from the common tendon from the
external condyle of the humerus, the external lateral ligament,
and the intermuscular septum; insertion, into the base of the
metacarpal bone of the middle finger on its radial side; action,
extends the wrist; nerve, posterior interosseous.

Posterior Superficial Layer.

Extensor Communis Digitorum (m. extensor communis
digitorum) . — Origin, from the external condyle of the humerus,
the deep fascia, and the intermuscular septa; insertion, by four
tendons into the second and third phalanges of all the fingers
(at the first phalanx they receive the insertion of the lum-
bricales and interossei) ; action, extends the fingers; nerve, pos-
terior interosseous.

Extensor Minimi Digiti (m. extensor digiti quinti pro-
prius). — Origin, from the common tendon from the external
condyle and the intermuscular septum; insertion, into the sec-
ond and third phalanges of the little finger ; action, extends the
little finger; nerve, posterior interosseous.

Extensor Carpi Ulnaris. — Origin, from the middle third
of the posterior border of the ulna, from the common tendon
from the external condyle of the humerus, and from the fascia
of the forearm; insertion, into the base of the metacarpal bone
of the little finger, on the ulnar side; action, extends the wrist;
nerve, posterior interosseous.

Anconeus (m. anconams). — Origin, from the outer con-
dyle of the humerus; insertion, into the upper fourth of the
posterior aspect of the shaft of the ulna and the side of the
olecranon; action, extends the forearm; nerve, musculospiral.

THE MUSCULAE SYSTEM. i;,;;

Posterior Deep Layer.

Supinator Eadii Brevis (///. supinator). — Origin, from
the external lateral Ligament of the elbow-joint, from the exter-
nal condyle of the humerus, from the ulna below the lesser sig-
moid cavity, and from the orbicular ligament of the radius;
insertion, into the neck, bicipital tuberosity and oblique line of
radius; the posterior interosseous nerve pierces this muscle;
n< Hun, supinates the hand; nerve, posterior interosseous.

Extensor Ossis Metacaepi Pollicis (m. abductor pollicis
longus). — Origin, middle third of posterior surface of radius,
posterior surface of lower three-fourths of shaft or ulna, ami
interosseous ligament; insertion, into base of metacarpal of
thumb; action, extends metacarpal of thumb; nerve, posterior
interosseous.

Extensor Longus Pollicis (rn. extensor poll icis longus).
— Origin, from the interosseous membrane and from the pos-
terior aspect of the shaft of the ulna ; insertion, into the base of
the last or terminal phalanx of the thumb; action, extends the
thumb; nerve, posterior interosseous.

Extensor Brevis Pollicis (m. extensor pollicis brevis).—
Origin, from the posterior aspect of the shaft of the radius and
from the interosseous membrane; insertion,, into the base of the
first phalanx of the thumb ; action, extends the thumb ; nerve,
posterior interosseous.

Extensor Indicis (m. extensor indicis proprius). — Origin,
from the posterior aspect of the ulna and from the interosseous
membrane; insertion, into the second and third phalanges of
the index linger, along with the tendon of the extensor com-
munis: action, extends the index finger; nerve, posterior inter-
osseous.

MUSCLES OF THE HAND.

These are divided into three groups — the radial region, the
ulnar region, and the palmar region.

Radial Region.

Abductob Pollicis (/». abductor pollicis brevis). — Origin.
from the annular ligamenl and ridge of the trapezium; inser-
tion, into base of the first phalanx of the thumb on its radial
side; action, abducts the thumb from the median line; nerve,
median.

0PPONEN8 I'oi.l.n is. Origin, from annular ligament and

palmar surf ace of the trapezium; insertion, into metacarpal bone

154 HUMAN ANATOMY.

of the thumb throughout the whole length of its radial side;
action, flexes the first metacarpal bone ; nerve, median.

Flexok Brevis Pollicis (m. flexor pollicis brevis) . — This
muscle consists of two portions., divided by tendon of flexor
longus pollicis; origin, superficial portion from outer two-thirds
of annular ligament and trapezium, deeper portion (by some
called adductor obliquus pollicis) from sheath of flexor carpi
radialis, the trapezoid, os magnum, and base of first, second,
and third metacarpal bones ; insertion, into either side of base
of first phalanx of thumb, the inner portion joining the adduc-
tor and the outer portion the abductor; each tendon has a sesa-
moid bone developed in it; action, adducts thumb toward median
line; nerves, ulnar and median.

Adductor Pollicis (Adductor Transversus Pollicis).
— Origin, from lower two-thirds palmar surface of middle meta-
carpal bone; insertion, into ulnar side of base of first thumb
phalanx and internal sesamoid bone ; action, adducts thumb ;
nerve, ulnar.

Ulnar Region.

Palmaris Brevis. — Origin, from palmar fascia and annu-
lar ligament; insertion, into skin of palm of hand; action,
wrinkles skin of hand; nerve, ulnar.

Abductor Minimi Digiti (m. abductor cligiti quinti). —
Origin, from pisiform bone and from tendon of flexor carpi
ulnaris; insertion, into base of first phalanx of little finger on
its ulnar side; action, abducts little finger from median line;
nerve, ulnar.

Flexor Brevis Minimi Digiti (m. flexor digiti quinti
brevis). — Origin, from annular ligament and tip of unciform
process of unciform bone; insertion, into the first phalanx of
little finger; action, flexes little finger; nerve, ulnar.

Opponents Minimi Digiti (m. opponens digiti quinti). —
Origin, from annular ligament and from unciform process of
unciform bone; insertion, into ulnar border of whole length of
metacarpal bone of little finger; action, flexes little finger;
nerve, ulnar.

Palmar Region.

Lumbricales. — Origin, by four fleshy tendons from the
tendons of the deep flexors — the first and second from the pal-
mar surface and radial side of the tendons of the index and
middle fingers, the third from the adjoining sides of the ten-
dons of- the middle and ring fingers, and the fourth from the

THE MUSCULAR SYSTEM. 155

adjoining sides of the tendons of the ring and little fingers ;
insertion, on dorsal aspect of each finger into the expansion of
the extensor communis digitorum ; action, abduct the fingers to
either side of the median line; nerves, ulnar and median.

Ij&EROSSEI -muscles consist of two groups, the dorsal and
palmar.

Dorsal Inteeossei (mm. interossei dorsales). — Origin,
from two heads from the adjacent sides of the metacarpal bones,
four in number; insertion, the first into the radial side of the
base of the first phalanx of the index finger, the second into the
radial side of the middle finger, the third into the ulnar side
of the middle finger, and the fourth into the ulnar side of the
ring finger, the middle finger having two, one 011 either side;
action, abduct the fingers from the median line; nerve, ulnar.

Palmar Interossei (mm. interossei volares). — Three in
number. Origin, the first from the entire length of the meta-
carpal bone of the index finger on its ulnar side, the second from
the ring linger on its radial side, and the third from the little
finger on its radial side; insertion, into the base of the first
phalanx and into the expansion of the extensor communis ten-
don of the same finger from which they arise; action, adduct the
fingers toward the median line; nerve, ulnar.

Muscles of the Lower Extremity,
iliac region.

Psoas Magnus (m. psoas major). — Origin, from the sides
and anterior surfaces of the transverse processes and bodies of
the last dorsal and all the lumbar vertebrae and the interver-
tebral substances between them; insertion, into the lesser tro-
chanter of the femur, unting with the tendon of the iliacus;
this muscle is in relation behind with the capsular ligament of
the nip, being separated from it by a synovial bursa; act inn.
and rotates the femur inward, and also flexes the trunk
and pelvis on the thigh; nerves, anterior branches of the lum-
bar nerves.

Psoas Pabvus (m. psoas minor). — Origin, from the lateral
Burfacee of the bodies of the Las! dorsal and first Lumbar vertebrae
and from the intervertebral substances between them; insertion.
into tin* iliopectinea] eminence, joining the iliac fascia; action .
assists the psoas magnue and renders tense the iliac fascia;
nerves, anterior branches of the lumbar.

[liacus. Origin, from the base of the sacrum and the ilio
lumbar Ligament behind, from, the iliac fossa and inner margin

156 HUMAN ANATOMY.

of the crest of the ilium and the anterior superior and! ante-
rior inferior spinous processes of the ilium; insertion, into the
oblique or intertrochanteric line of the femur to the outer side
of the insertion of the psoas; action, flexes and rotates the
femur inward and flexes the trunk and pelvis on the thigh;
nerves, anterior crural and the anterior branches of the lumbar.

FEMORAL AND GLUTEAL REGION.

Tensor Vaginae FEmoris, or tensor fasciae femoris (m.
tensor vagina? femoris, or m. tensor fascia? femoris) . — Origin,
from the anterior superior spinous process between the sartorius
and the gluteus medius, and from the fore part of the outer lip
of the crest of the ilium; insertion, into the fascia lata, about
the upper fourth of the outer side of the thigh ; action, renders
tense the fascia lata; nerve, superior gluteal.

Sartorius. — Origin, from the anterior superior spinous
process of the ilium and the upper part of the notch below;
insertion, into the inner and upper part of the shaft of the
tibia; action, flexes the leg upon the thigh and the thigh upon
the pelvis; nerve, branches of the anterior crural.

Quadriceps Extensor (to. quadriceps femoris). — This
extensive muscle covers the front and sides of the femur and
consists of four portions — the rectus femoris, the vastus exter-
nus, the vastus interims and the crureus.

Rectus Femoris. — Origin, by two heads — one, the long
head, from the groove above the brim of the acetabulum; the
other, the short head, from the anterior inferior spinous process
of the ilium ; insertion, by the common tendon into the patella ;
action, extends the leg upon the thigh ; nerves, branches of the
anterior crural.

Vastus Externus (m. vastus lateralis). — Forms the
greater part of the quadriceps extensor. Origin, by an exten-
sive aponeurosis extending from the tubercle of the femur along
the anterior border of the great trochanter and the whole length
of the outer lip of the linea aspera; insertion, into the outer
portion of the patella, joining the common tendon; action,
extends the leg on the thigh; nerves, branches of the anterior
crural.

Vastus Internus and Crureus (m. vastus medialis el m.
vastus intermedins) .■ — Origin, by a tendinous aponeurosis ex-
tending from the neck of the femur throughout the whole length
of the inner lip of the linea aspera ; insertion, into the common
tendon, together with the rectus femoris and the vastus exter-

THE MUSCULAR SYSTEM.

157

mis; action, extends the leg on the thigh; nerves, branches of
the anterior crural.

Subcrureus (m. articularis genu). — Origin, from the an-
terior aspect of the lower part of the shaft of the femur ; inser-
tion, into the synovial sac behind the patella.

Fig. 73.

Anterior femoral re-
gion ; 4, tensor vaginae
femoris; 5, sartorius; 6,
rectus; 7, vastus exter-
nus; 8, vastus internus;
10, iliacus; 11, psoas; 12,
pi i t ineus; 13, adductor
longus; 14, adductor mag-
nus; 16, gracilis.

Fig. 74.

Posterior femoral re-
gion; 1, gluteus medius;
2, gluteus rnaximus; 3,
vastus externus; 4, bi-
ceps; 0, semitendinosus;
7, semimembranosus; s,
gracilis.

GRACILIS. — Origin , from the inner margin of the ramus ->l
the ischium and the pubes ; insertion, into the innei asped "I'
the -haft <»f the tibia, below the tuberosity; action, flexes the

158 HUMAN ANATOMY.

leg and draws it inward, assisting the sartorius; nerve, the
obturator.

Pectineus. — Origin, from the tendinous prolongation of
Gimbernat's ligament and the linea iliopectinea ; insertion, into
the rough line leading to the linea aspera from the lesser tro-
chanter ; action, adducts the thigh ; nerves, obturator, the acces-
sory obturator, and branches of the anterior crural.

Adductor Longus. — Origin, from the front of the os pubis
below the crest; insertion, into the middle third of the linea
aspera, between the adductor magnus and the vastus internus ;
action, adducts the thigh; nerve, obturator.

Adductor Brevis. — Origin, from the outer aspect of the
descending ramus of the pubes, between obturator externus and
the gracilis; insertion, into the upper part of the linea aspera;
action, adducts the thigh; nerves, branches of the obturator.

Adductor Magnus. — Origin, from the tuberosity of the
ischium, the ascending ramus of the ischium, and from the
descending ramus of the pubes; insertion, into the rough line
leading to the linea aspera from the great trochanter to the
inner side of the gluteus maximus and into the adductor tuber-
cle above the inner condyle of the femur {vide page 64) ; action,
adducts the thigh; nerves, the obturator and a branch from the
great sciatic.

Gluteus Maximus (m. glutceus maximus). — Origin, from
the superior curved line of the ilium, the posterior aspect of the
last segment of the sacrum, the border of the coccyx, and the
surface of the great sacrosciatic and posterior sacroiliac liga-
ments ; insertion, into' the rough line leading to the linea aspera
from the great trochanter, between the adductor magnus and
the vastus externus, and into the fascia lata; action, it is a ten-
sor of the fascia lata, and .an external rotator and extensor of
the thigh; nerves, the inferior gluteal and a branch from the
sacral plexus.

Gluteus Medius (m. glutceus medius). — Origin, from the
outer lip of the crest and the outer aspect of the ilium, between
the middle and superior curved lines, and from the gluteal apo-
neurosis; insertion, into the oblique line on the outer surface of
the great trochanter; action, rotates the thigh outward; nerve,
from the superior gluteal.

Gluteus Minimus (m. glutceus minimus). — Origin, from
the border of the great sacrosciatic notch and between the infe-
rior and middle curved lines of the outer aspect of the ilium;
insertion, into a depression on the front border of the great

THE MUSCULAR SYSTEM. i.v.i

trochanter; action, rotates the thigh inward; nerve, superior
gluteal.

PYEIFORMIS (in. piriformis). — Origin, from the anterior
surface of the sacrum, between the first to the fourth anterior
sacral foramen, and from the margin of the great sacrosciatic
foramen, and from the anterior aspect of the great sacrosciatic
ligament; insertion , into the upper border of the great tro-
chanter, with the tendon of the obturator interims; action.
rotates femur outward; nerve, obturator.

Obturator Intbenus. — Origin, from the inner side of the
obturator foramen and the internal surface of obturator mem-
brane and the anterior and external wall of the pelvis; it passes
out of the pelvis through the lesser sacrosciatic notch and
receives the tendons of the gemelli muscles; insertion, into the
upper border of the great trochanter in front of the pyriformis;
action, rotates the thigh outward; nerves, branches from the
sacral plexus.

Gemelli consist of two muscles — gemellus superior and
gemellus inferior.

G-emellus Superior. — Origin, from the outer aspect of
the spine of the ischium; insertion, into the tendon of the
obturator interims.

Gemellus Inferior. — Origin, from the outer border of
tuberosity of the ischium; insertion, into the lower portion of
the tendon of the obturator interims ; action, rotates the thigh
outward; nerves, branches of the sacral plexus.

Quadrattjs Femoris. — Origin, from the external border of
the tuberosity of the ischium; insertion, into the upper part of
the linea quadrati, on the posterior aspect of the trochanter
major; action, rotates the thigh outward; nerves, branches of
the sacral plexus.

Obturator Exterxus. — Origin, from the inner two-thirds
of the anterior aspect of the obturator membrane and the ten-
dinons arch covering the canal for the obturator vessels and
nerves, and the descending ramus of the pubis and the ascend-
ing ramus of the ischium; insertion, into the digital fossa of the
femur; action, rotates the thigh outward; nerve, the obturator.

Bn EPS, or biceps flexoT cruris(wi. l>i<<-jis femoris). — Origin,
arises by two heads — the long head [caput longum), from the
lower and inner facet of the tuberosity of the ischium by a
'•oiiiiiion tendon to the long head of the seinitendinostis ; the
short bead (caput breve), from the outer lip of the linea aspera,
tween the vastus externue ami the adductor magnus; insertion,

outer ?-id<j of head of fibula, by two portions, on either side of

160 HUMAN ANATOMY.

the external lateral ligament of the knee joint, sending a band
forward to the outer tuberosity of the tibia. This tendon forms
the outer hamstring; action, flexes the leg upon the thigh ; nerve,
the great sciatic.

Semitendinosus. — Origin, from a common tendon, to-
gether with the long head of the biceps, from the tuberosity of
the ischium; insertion, into the inner and upper part of the
shaft of the tibia; action, rotates the leg inward; nerve, the
great sciatic.

Semimembranosus. — Origin, from the outer and upper
facet of the tuberosity of the ischium to the outer side and above
the origin of the semimembranosus and the biceps ; insertion,
into the posterior inner aspect of the inner tuberosity of the
tibia, under the internal lateral ligament by three portions — the
internal portion into the inner side of the internal tuberosity,
the posterior portion into the posterior part of the outer con-
dyle of the femur, forming the principal part of the posterior
ligament of the knee joint, and middle portion into the poste-
rior aspect of the inner tuberosity; action, flexes the leg upon
the thigh; nerve, the great sciatic.

These two tendons (semimembranosus and semitendino-
sus), together with the gracilis and sartorius, form the inner
hamstring.

MUSCLES OF THE LEG.

Anterior Set.

Tibialis Anticus (m. tibialis anterior). — Origin, from
the upper and outer two-thirds of the shaft of the tibia, the
interosseous membrane, and the intermuscular septum between
it and the extensor longus digitorum; insertion, into the lower
and inner aspect of the internal cuneiform bone and base of the
first metatarsal bone; action, flexes the foot; nerve, the anterior
tibial.

Extensor Proprius Pollicis (to. extensor liallucis lon-
gus).— Origin, from the anterior aspect of the fibula and the
interosseous membrane and the intermuscular septum between
it and the extensor longus digitorum; insertion, into the base
of the last phalanx of the great toe; action, extends the great
toe; nerve, the anterior tibial.

Extensor Longus Digitorum (m. extensor digitorum. lon-
gus).— Origin, from the upper two-thirds of the anterior aspect
of the shaft of the fibula and the outer tuberosity of the tibia,
from the deep fascia of the interosseous membrane and the

THE MUSCULAR SYSTEM.

161

intermuscular septum, between it and the perinei on the outer
and the tibialis anticus on the inner side; insertion, by three
tendons into the bases of the first and second phalanges of the
four lesser toes, the innermost tendon dividing into two; each
tendon (except the fourth) is joined opposite the metatarso-

FiG. 75.

Anterior muscles of leg; 3, tibialis
anticus; 4, extensor longus digi-
torum; 5, extensor proprius pollicis;
6, i" roneus tertius; 7, peroneus lon-
gus; 8, peroneus brevis.

Fig. 76.

Posterior muscles of leg; 4, pop-
liteus; 5, gastrocnemius; 6, tenda
Achillis; 8, tendons of peroneus lon-
gus and brevis; 9, tibialis posticus
and flexors.

phalangeal joint by the tendon of the extensor brevis digitorum,
and receives an expansion from the lumbricales and inteiossei;
at the first interphalangeal articulation the tendons divide into
three slips — the middle one for insertion into the second pha-
lanx, and the olhcr two uniting to be inserted into the base

11

162 HUMAN ANATOMY.

of the third; action, extends the phalanges and, continuing,
flexes the foot npon the leg; nerve, the anterior tibial.

Peroneus Tertius (ra. peronams tertius). — Origin, from
the lower front part of the fibula on its outer side, from the
interosseous membrane, and the intermuscular septum between
it and the peroneus brevis; insertion, into the metatarsal bone
of the little toe; action, flexes the tarsus upon the leg; nerve,
the anterior tibial.

Posterior Superficial Set.

Gastrocnemius. — Origin, from the upper and back part
of the external and internal condyles of the femur on either
side, above the origin of the popliteus, and from the supracon-
dyloid ridges; insertion, by joining with the tendon of the soleus
to form the tendo Achillis ; action, extends the foot ; nerve), from
the internal popliteal.

Soleus. — Origin, from the oblique line of the tibia, from
the middle third of the internal border, and from the posterior
surface of the head of the fibula; insertion, by joining with the
tendon of the gastrocnemius to form the tendo Achillis ; action,
extends the foot; nerve, the internal popliteal.

Tendo Achillis (tendo calcaneus). — Origin, from the
union of the gastrocnemius and soleus; is the largest and strong-
est tendon in the body; it is inserted into the inferior surface
of the posterior tuberosity of the os calcis, having a synovial
bursa (bursa tendinis calcanei [Achillis]) between it and the
bone.

Plantaris. — Origin, from the posterior ligament of the
knee-joint and the lower portion of the outer division of the
linea aspera; insertion, into the posterior part of the os calcis
to the inner side of the tendo Achillis; action, the rudiment of
a muscle intended to render tense the plantar fascia ; nerve, the
internal popliteal.

Posterior Deep Set.

Popliteus. — Origin, from the outer side of the external
condyle, from the posterior ligament of the knee-joint; inser-
tion, above the oblique line on the posterior aspect of the shaft
of the tibia; action, assists in flexing the leg; nerve, the internal
popliteal.

Flexor Longus Hallucis (ra. flexor hallucis). — Origin,
from the lower two-thirds of the internal surface of the fibula,
from the lower part of the interosseous membrane, fascia cov-

THE MUSCULAR SYSTEM.

163

ering tibialis posticus, and from the intermuscular septum; n
passes behind the internal malleolus; insertion, into the base of
the last phalanx of the great toe; nerve, posterior tibial.

Flexor Long us Digitorum — Pereorans (ra. flexor digi
torn in longus) . — Origin, from the posterior aspect of the tibia.
below the oblique line; it passes behind the internal malleolus-
insertion, into the bases of the last phalanges of the four lesser
toes, passing- through the division in the tendons of the flexor
brevis digitorum; action, flexes the phalanges and. continuing,
extends the foot on the leg; inrrr, the posterior tibial.

Tibialis Posticus (m. tibialis posterior) .—Origin from
the posterior aspect of the shaft of the tibia, and from the upper
two-thirds of the shaft of the fibula, and from the whole length
of the interosseous membrane and the intermuscular septa on
either side of it; it passes behind the inner malleolus; insertion,
into the internal cuneiform bone and the tuberosity of the sca-
phoid ; it contains a sesamoid bone in its tendon; action, extends
the tarsus upon the leg; nerve, the posterior tibial.

Fibular Region.

Peroneus Longus (m. peronceus longus). — Origin from
the upper two-thirds of the shaft of the fibula, the head of the
fibula, the intermuscular septa, and the deep fascia; it passes
behind the outer malleolus along with the peroneus brevis-
insertion,, into the base of the metatarsal bone of the great toe;
this tendon changes its course twice, first at the external mal-
colu-, second at the cuboid bone, and usually has a sesamoid
bone developed in its tendon; action, extends and everts the foot
upon the leg; nerve, musculocutaneous branch of the external

popliteal.

Peroneus Brevis (m. peronmis brevis) .—Origin, from the
outer. and middle third of the m,„la :lnd the intermuscular septa
on either sid,.; insertion, into the upper surface of the base of
the metatarsal bone of the little toe; action, extends the foot
"1"") the leg; nerve, musculocutaneous branch of the external
popliteal.

MUSCLES of THE FOOT.

Dorsal Region.

Extbnsob Brevis Digitorum (m. extensor digitorum
brevw) Origin, from the external calcaneoastragaloid liga-
ment, Iron, the annular ligament, and from the oilier side' of

164 HUMAN ANATOMY.

the os calcis; insertion, by four tendons — the first one into the
first phalanx of the great toe, the other three into the long
extensor tendons of the second, third, and fourth toes on their
outer sides; action, extends the phalanges of the four inner toes
and the first phalanx of the great toe ; nerve, the anterior tibial.

Plantar Region.
The muscles of this region are divided into four sets.

First Set.

Abductor Hallucis. — Origin, from the internal annular
ligament, from the inner tubercle of the os calcis, from the
intermuscular septum on its outer side and plantar fascia ; inser-
tion, into the base of the first phalanx of the great toe on its
inner side; action, abducts the great toe; nerve, branch of the
internal plantar.

Plexor Brevis Digitorum — Perforatum (ra. flexor digi-
torum brevis). — Origin, from the inner tubercle of the os calcis,
from the plantar fascia and the intermuscular septa between it
and the muscles on either side; insertion, into the second
phalanges by a process on either side, allowing the passage of
the tendon of the flexor longus digitorum; action, flexes second
phalanges upon first and continuing may flex first phalanges
bringing toes together; nerve,, from the internal plantar.

Abductor Minimi Digiti (m. abductor digiti quinti). —
Origin, from the plantar fascia, from the os calcis in front of
the tubercle, and from the intermuscular septum on its inner
side; insertion, into the first phalanx of the little toe on its
outer side; action, abducts little toe; nerve, external plantar.

Second Set.

Flexor Accessorius (m. quadratus plantar). — Origin, by
two heads, one from the os calcis in front of the outer tubercle,
the other from the inner surface of the os calcis and the cal-
caneoscaphoid ligament; insertion, by a common tendon into
the tendon of the flexor longus digitorum; action, accessory to
the long flexor; nerve, external' plantar.

Lumbricales. — Four small muscles. Origin, from the ten-
dons of the flexor longus digitorum, after their division, each
one arising from two tendons; insertion, into, the base of the
first phalanx of the same toe and the tendinous expansion of
the extensor longus digitorum; nerves, the external plantar
nerve supplies the two external, the internal plantar nerve the
two internal, muscles.

THE -MUSCULAR SYSTEM. 165

Third Set.

Flexor Brevis Hallucis (m. flexor hallucis obliquus).—
Origin, from the external cuneiform bone, and the internal bor-
der of the cuboid bone, and the tendinous expansion of the
tibialis posticus; insertion, into the first phalanx of the great
toe on either side; action, flexes first phalanx of great toe;
nerves, the internal plantar and sometimes a branch from the
external plantar.

Adductor Hallucis. — Origin, from the bases of the sec-
ond, third, and fourth metatarsal bones and from the sheath of
the tendon of the peroneus longus; insertion, into the base of
the first phalanx of the great toe on the outer side; nerve, exter-
nal plantar.

Flexor Brevis Minimi Digiti (m. flexor digiti quinti
brevis). —Origin, from the sheath of the peroneus longus and
the base of the metatarsal bone of the little toe; insert ion, into
the outer side of the base of the little toe; nerve, external
plantar.

Adductor Transversus Hallucis (m. transversus pedis).
— Origin, from the inferior metatarsophalangeal ligaments of
the three outer toes, or at other times from the third and fourth,
and also from the transverse ligament of the metatarsus; inser-
tion, into the outer side of the first phalanx of the great toe;
nerve, external plantar.

Fourth Set.

Dorsal Interossei (m. interossei dorsal es). — Four in
number. Origin, by two heads from the adjoining bases of, the
metatarsal bones; insertion, into the bases oi' the first phalanges
of the second, third and fourth toes, the second having two,
one on either side, and the third and fourth on their outer side";
action, abduct the toes from the middle line of the second toe'
nerve, external plantar.

PLANTAR I\Ti:i;ossr;r (m. interossei plan tares). —Three in
number. Origin, from the bases of inner side of the third,
fourth and fifth metatarsal bones; insertion, into the bases of
the first phalanges on the same side; action, adduct the toes
toward a middle line, which would pass through the sec.nd toe-
/" rve, the external plantar.

The Pasoias ( Eascls).

'I'Im' fasciae are strong, fibrous (fibroareolar) investments

protecting and binding together l he muscles, and m places form-

1(36 HUMAN ANATOMY.

ing ligaments and intermuscular septa. They consist, for the
most part, of two layers, a superficial and a deep.

Fascias of the Cranium and Face. — The superficial fas-
cia of the head and face is everywhere intimately connected to
the skin, except over the temporal region, where it forms a dis-
tinct lamina, inclosing the superficial temporal vessels and auric-
ular muscles.

The deep temporal fascia (fascia temporalis) is a dense,
fibrous membrane, attached to the margins of the temporal fossa
and zygoma, and from which, in part, the temporal muscle
arises.

Fascias of the Neck. — The superficial fascia is continu-
ous below with that covering the pectoral muscles and deltoid,
and blends above with the superficial facial muscles and fascia.

The deep fascia (fascia colli) adheres below to the clavicle
and sternum, and is continuous with the thoracic fascia. As it
ascends the neck it ensheathes the great vessels of the neck,
sends processes to the larynx, trachea, pharynx and esophagus,
and above ensheathes the submaxillary and parotid glands, and
forms the stylomaxillary, or stylomandibular ligament (liga-
mentum stylomandibular e) .

Fascias of the Trunk. — The superficial fascia may con-
sist of two or more layers in places. It is continuous above
with the fascias of the neck and upper extremity, and below
with the thigh. Over the pectoral region the mammary glands
are inclosed between its layers (ligamenta suspensoria) ; below
the level of the umbilicus it again divides into two layers, the
superficial of which is continuous with the superficial layer of
the superficial fascia in the thigh, while the deep layer is
attached to the crest of the ilium and Poupart's ligament.

The deep fascia forms intermuscular septa and aponeuroses.

The lumbar fascia divides into three layers, inclosing the
quadratus lumborum, multifidus spinas and erector spina? mus-
cles, and gives attachment to the internal oblique and trans-
versalis muscles. Its anterior and middle layers are attached
to the transverse processes, and its posterior layer to the spinous
processes. Above, its anterior layer is attached to the lower bor-
der of the last rib, forming the ligamentum arcuatum externum
'(arcus> lumbocostalis lateralis). The ligamentum arcuatum in-
ternum (areas lumbocostalis medialis) extends from the body
of the first or second lumbar vertebra to the transverse process,
inclosing the psoas magnus muscle.

Abdominal and Pelvic Fascia. — The transversalis fascia
is a thin aponeurosis between the peritoneum and transversalis

THE MUSCULAR SYSTEM. 167

muscle. It is attached below to the pubes, pectineal line, Pou-
partfs Ligament and the femoral vessels, and becomes continu-
ous with the iliac and pelvic fascia. The pelvic fascia (fascia
pelvis) lines the pelvic cavity throughout, attached to the sym-
physis pubis, margin of obturator foramen, and the sacrum and
becomes continuous with the iliac and transversalis fascias.
[Below it forms the arcus tendinece, for the origin of muscles and
the division into the rectovesical and obturator fascias (vide
Perineum).

The iliac fascia (fascia iliaca) is a thin, fibrous mem-
brane investing the psoas and iliacus muscles. Above it is
attached to the Ligamentum arcuatum internum, laterally, with
the bodies of the vertebras and sacrum, and below it is attached
to Poupart's ligament, the femoral vessels, pectineal eminence,
and the capsule of the hip-joint.

Upper Extremity. — The superficial fascia is a thin mem-
brane, inclosing the parts throughout, and adherent to the deep
fascia beneath.

The deep fascia is very dense and strong. It gives off
numerous intermuscular septa, and is attached to the olecranon
and back part of ulna, and becomes continuous below with the
anterior and posterior annular ligaments of the wrist-joint, both
of which it forms.

The anterior annular ligament (ligamentum carpi trans-
versum) is attached to the ridge of the trapezium, the tuberosity
of the scaphoid, the unciform process of the unciform, and the
pisiform hone, forming a strong, iibrous arch, under which the
flexor tendons of the lingers pass.

The posterior annular ligament (ligamentum- carpi dorsale)
is attached to the radius, ulna, cuneiform and pisiform hones,
and the palmar fascia, forming a fibrous arch for the passage
of the extensors of the fingers.

The palmar fascia (aponeurosis palmaris) is an exceedingly
dense, triangular mass of adipose and fibrous tissue, attached

behind to the anterior annular lip 'lit, and in front divides

into tour fasiculi, each of which subdivides into two, inserted
into the lateral ligaments of the metacarpophalangeal articula-
tion-. These digitatione allow the passage of the flexor digi-
toruni tendons, the digital vessels and nerves. It is attached
above to the skin, and laterally gives off vertical septa, which
separate the middle from the lateral groups of palmar muscles.

168 HUMAN ANATOMY.

EASCTAS OF THE LOWER EXTREMITY.

The superficial fascia- resembles that in other localities,
except that, in the front of the thigh, it consists of two or
more layers between which are found the superficial vessels,
nerves and lymphatic glands. The under layer is attached to
the margins of the saphenous opening, where it is perforated by
numerous lymphatic vessels and blood-vessels ; hence its name,
cribriform fascia {fascia cribrosa).

The deep fascia of the thigh, or fascia lata, is a dense
fibrous aponeurosis attached to the pubes, Poupart's ligament,
crest of the ilium, sacrum and coccyx, inclosing the gluteus
maximus and tensor vaginae f emoris between its layers, attached
to the linea aspera, and below to all the bony points about the
knee joint, being attached to the head of the fibula and tuber-
osities of the tibia by the iliotibial band (trnctus ilioiibialis
[M aissiati] ) .

The saphenous opening (fossa ovalis) is a large opening in
the fascia lata at its upper and inner part closed by the crib-
riform fascia. Through it pass the internal or long saphenous
vein, the superficial epigastric and external pudic arteries, and
lymphatics. It is formed by the iliac and pubic portions of the
fascia lata. The iliac portion becomes continuous at the pec-
tineal line with Gimbernat's ligament, and its free border forms
the falciform border (vide Femoral Hernia).

The pubic portion is continuous behind the femoral vessels
with the femoral sheath and the iliac and psoas fascia. At the
lower border of the saphenous opening it is continuous with the
iliac portion of the fascia lata.

The deep fascia of the leg (fascia cruris) is attached above
to the bony points about the knee, continuous with the fascia
lata, invests the leg completely, except the inner surface of the
tibia, sends in a deep transverse fascia between the superficial
and deep muscles on the posterior aspect of the leg, and below
becomes continuous with the annular ligament of the ankle-
joint.

The annular ligament of the ankle joint consists of three
portions — the internal, external and anterior. It is attached
to the bony points about the ankle joint, the external and inter-
nal malleoli, surfaces of the os calcis, and allows the passage
of the muscles to the foot.

The dorsal aponeurosis of the foot (fascia dorsalis pedis)
covers the back of the foot, uniting with the plantar fascia at

THE MUSCULAR SYSTEM. 1G9

the sides, and terminating anteriorly at the heads of the meta-
tarsal hones.

The plantar aponeurosis (aponeurosis plantaris) consists of
three portions, a central and two lateral portions.

The middle portion commences at the inner tubercle of the
os calcis and proceeds, gradually becoming broader, to the heads
of the metatarsal bones, where it divides into four branches,
each of which nearly surrounds the corresponding flexor tendon
to which it gives passage, and is inserted into the edges of the
dorsal expansion of the first phalanges.

The inner portion arises from the internal annular liga-
ment, covers the abductor pollicis muscle, and joins the dorsal
aponeurosis internally and the internal septum externally.

The outer portion, much stronger, arises from the os calcis,
covers the abductor minimi digiti muscle, and joins the external
plantar septum internally and dorsal aponeurosis externally, and
is firmly attached to the base of the fifth metatarsal bone.

Numerous septa pass from the upper surface of the plantar
fascia between the plantar muscles and tendons to be inserted
into the metatarsal and tarsal bones.

THE HEART AND VASCULAR SYSTEM.

The pericaedium is a conical, membranous, closed sac,
surrounding the heart and the roots of the great vessels. It
occupies the greater part of the middle mediastinum, its apex
upward, its base downward and attached to the central tendon
of the diaphragm. It is a fibroserous membrane, consisting of
an outer fibrous coat and an inner serous coat. The latter is
composed of a visceral layer (epicardvum) reflected over the
heart and vessels, and a parietal layer lining the inner surface
of the fibrous sac. It secretes a thin, serous fluid.

The fibrous coat becomes continuous above with the deep
layer of the cervical fascia, being prolonged upward on the
outer surfaces of all the great vessels, except the inferior vena
cava.

The Heart (Cor).

The heart is a hollow, muscular organ, placed obliquely
within the chest, and inclosed within the pericardium. Its base
(basis cordis) is directed upward and backward, opposite the
fifth to eighth dorsal vertebrae; its apex (apex cordis) down-
ward to the left, opposite the interspace between the fifth and
sixth costal cartilages. Its weight is about ten to twelve ounces
in male, eight to ten in female ;, length five inches, breadth three
and a half inches, thickness two and a half inches.

It is divided into four parts : —

Right auricle, Left auricle,

Right ventricle, Left ventricle,

an auricle and ventricle on each side. This division is indicated
on both surfaces of the organ by two grooves crossing each other
and named, from their position, the longitudinal or the inter-
ventricular (sulci longitudinalis) , the transverse or the auric-
uloventricular (sulcus coronarius) grooves.

Eight Auricle. — The right auricle (atrium dextrum)
consists of two portions — a sinus or atrium and an appendix
auriculce, which projects to the right side of the origin of the
aorta. The walls at the fore and outer part and in the auricu-
lar appendage are thickened by musculi pectinati. The mus-

(170)

THE HEART AND VASCULAR SYSTEM.

171

cular tissue of the auricles is connected with that of the
ventricles by a small band of fibers, the auriculoventricular
fasciculus, or "bundle of His."

This smooth ridge is known inside the auricle as the crista
terminate of His, and outside the groove is called the sulcus
terminalis of His. Its interior presents the following parts:—

Openings of the superior and inferior vena' cava', neither
of which are protected by valves :

Opening of coronary sinus {sinus coronarius), protected by
a valve of two unequal segments— the coronary valve;

Fig. 77.

Right side of heart: a, apex; 6, right ventricle; d, pulmonary
artery; e, f, chords tendineas; p, aorta; 3, superior vena cava; 5,
inferior vena cava.

Foramina Thebesii (foramina vcnarum minimarum), mi-
nute foramina returning the blood from the heart-muscle;

stachiap valve (valvula rcmr n,r,r info-ions [Eu-
rtachW]), the remainfi of a fetal structure, extending from the
right Of the orifice Of the inferior vena cava to the outer border

of the oval foramen ;

Fossa oralis, the obliterated foramen ovale of fetal lite:
AnnuTui ovalis {limbus fossm oralis | VieussenU]) , the oval

margin of the preceding structure;

Tubercle of Lower (tuberculwn intervenosum \Lowen\),Q

small rudimental projection on the right wall, directing the

blood toward the annciilo\eiit ri.ular opening;

172 HUMAN ANATOMY.

Musculi pectinati, elevated muscular columns before re-
ferred to;

Auriculoventricular opening (ostium venosum dextrum),
an oval aperture about one inch in diameter, surrounded by a
fibrous ring, and protected by the tricuspid valve.

The Left Auricle (atrium sinistrum). — The left auricle
is smaller, and its walls somewhat thicker than the right, and
consists of a cuboidal sinus and an elongated appendix auriculae.
Its interior surface is smooth, except the auricular appendage,
which is provided with musculi pectinati, and presents the fol-
lowing openings : —

Pulmonary veins, four in number, two on either side; they
are without valves;

Auriculoventricular opening (ostium venosum ventriculi
sinistri), an oval aperture, rather smaller than the right, and
protected by the bicuspid or mitral valve.

The Eight Ventricle (ventriculus dexter). — The right
ventricle is triangular, with thick walls (one-quarter inch), and
occupies the anterior part of the organ. Its capacity is about
three fluidounces. It presents the following: —

Infundibulum (conus arteriosus), a conical pouch, from
which the pulmonary artery arises ;

Columnse carneae (trabecular carnece), muscular columns
projecting from the inner surface, three or four of which (mus-
culi papillares) give attachment to the chordae tendineae;

Chordce tendinew, delicate tendinous cords, connecting the
margins and central portions of the tricuspid valve with the
columns carneae;

Tricuspid valve (valvula tricuspidalis) , consists of three
segments or cusps (cuspides) which consist of triangular dupli-
cations of endocardium, strengthened by fibrous tissue; they are
attached by their bases to the auriculoventricular orifice (an-
nulus fibrosis dexter) and their free margins give attachment to
the chordae tendineae (ostium venosum ventriculi dextri).

Semilunar valves (valvular sem.ilunares a. pvlmonalis) con-
sist of three semicircular folds, guarding the orifice of the pul-
monary artery; their free margins are thickened by nodules, the
corpora Arantii (nodulus valvules semilunaris [Arantii~\) ;

Opening of the pulmonary artery (ostium- arteriosum) , at
the apex of the conus arteriosus, is circular in outline and pro-
tected by the semilunar valves;

Sinuses of Valsalva^ three pouches, situated one behind each
semilunar valve.

THE HEART AND VASCULAR SYSTEM. 173

The Left Ventricle (ventricutus sinister). — The left
ventricle is longer, more conical, and its walls three times as
thick a< the right. It forms the apex {apex cordis) and most
of the posterior and inferior (facies diaphragmatica) portion of
the heart. It presents the following parts in its interior :—
Col urn iter carnece, and

Chorda tendinece, much the same as the right; _

Uiriculoventricular opening {ostium venosum ventnculi
sinistri), a little smaller than the corresponding orifice on the
right side, similarly formed, and protected by the mitral valve;
' The mitral valve {valvula bicusptdalis) consists of two
unequal segments, attached the same as the tricuspid, and also
affording attachment to the chordae tendmese;

Aortic opening {ostium arteriosum), a circular opening to
the right of the auriculoventricular opening;

The semilunar valves {valvule semilunares aorta'), three
in number, surround the aorta, and are larger and stronger than
those on the right side ; .

Sinus aortici (sinuses of Valsalva) are depressions situated

behind each valve. . „

Structure of the Heart. — The heart is composed 01
finely striated muscular walls, with external serous covering
from the pericardium and internal serous lining the endo-
cardium the latter continuous with that of blood vessels. The
endocardium is a thin, translucent membrane, consisting ot
endothelium and a fine basement membrane, beneath which is
a fibrocystic layer. The doublings of these layers constitute the
valve< The tricuspid and mitral valves, as well as the aortic
and pulmonary, are surrounded by a fibroelastic ring {annulus
fibrosa), which furnishes a "puctum fixuur for the varying
musculature of the heart. . .

The muscular structure consists of an intricate interlace-
ment of fibrous Lands. Of these there are two groups— those
of the auricles and those of the ventricles.

The former consist of a superficial transverse set and the
internal or deep set, of which there are the looped and the
circular.

The fibers of the ventricles consist of seven layers m a gen-
era] oblique and circular manner, ami terminating in a whorl
,„. ,.,„•/,,,. a1 the apex, some of the abers fern, mating m the
oolumnse carnese, musculi pectinati, while others ascend, torm-
ina i„ their course a twisted loop like the figure s. The arteries
of the Lean are i he ri-ht and left coronarv. The veins are the
anterior or great, middle <>r posterior cardiac, the left auricular,

174 HUMAN ANATOMY.

the right auricular and venge Thebesii. The lymphatics end in
thoracic and right lymphatic ducts. The nerves are derived
from the cardiac plexus of pneumogastric, spinal and great
sympathetic.

The Vascular System.

The vascular system consists of four sets of vessels — ar-
teries, capillaries, veins and lymphatics. Anastomoses are
common.

The vessels that convey blood to and from the tissues of
the body generally constitute the general system.

Those that carry blood to and from the lungs form the
pulmonary system.

The vessels passing to the liver form the portal system.

The arteries, for the most part, are composed of three
coats : —

Tunica adventitia, or external coat, consists of fibrous tis-
sue, thinnest on the largest trunks, and disappears in those
which merge into capillaries.

The tunica media,, or middle coat, is thickest in the large
trunks, and consists mainly of elastic tissue, together with some
unstriated muscle and some connective tissue; in smallest arter-
ies it consists alone of muscular tissue.

The tunica intima, or internal coat, thinnest, most trans-
parent and elastic, is composed of lining endothelium, basement
membrane, and layers of elastic tissue. The elastic tissue in
layers forms nets, constituting so-called perforated or fenestrated
membrane. It becomes continuous with capillaries. The walls
of larger arteries are supplied by blood vessels from neighboring
arteries. Nutrient arteries form a network of capillaries, and
returning veins empty into contiguous veins. The nerves are
both medullated and non-medullated and chiefly pass to the
muscle-fibers.

Arteries dilate and contract with the action of the heart,
constituting the ptdse.

The veins. — Larger, more numerous, and more capacious
than the arteries, with one exception (the portal vein) they
convey blood to the heart. The large veins emptying into the
heart are : —

Four pulmonary ;

Superior and inferior vense cavse;

Coronary veins from walls of the heart through the coronary
sinus.

THE HEART AND VASCULAR SYSTEM. 175

The larger arteries have, each, one companion vein, the
medium arteries two. In some positions they form venous
plexuses, corresponding to arterial anastomoses.

Many large veins have valves, usually in pairs, attached by
convex border.

There are, however, no valves in the pulmonary, superior
and inferior cavae, azygos, portal vein and branches, hepatic,
renal, uterine, and spinal, and most of those of head or neck.

In certain membranes and organs channels exist, lined by
internal coat of blood vessel, termed venous sinuses, as in the
dura mater, bones and uterus.

The coats of the veins are similar to those of the arteries.
and differ chiefly in the weakness of the middle or muscular
coat, which allows them to remain open.

The external fibrous coat has also longitudinal, unstnated
muscular tissue in veins of abdominal cavity: —

The middle, unstriated muscular and fibrous tissue;
The internal, no fenestrated membrane.
The walls have nutritive vessels, and are well supplied with
non-medullated and medullated nerves, which pass to the mus-
cular coat. _ ,

Both arteries and veins are insensitive m healthy
Tin: capillaries communicate with the terminations of
the arteries and veins, and do not communicate with tissue
proper which is supplied by imbibition. They vary in size in
different organs from y2ooo to Vsooo inch in diameter, but all
permit the passage of blood corpuscles. Their form is depend-
ent on the form of tissue supplied.

Composition of the Blood. — Blood within the vessels is
a perfect fluid, alkaline reaction, saline taste, average specific
gravity 1060, and of feeble, peculiar odor. Within the arterial
jselfl it is bright red in color, becoming in the veins (partic-
ularly the venae portae and pulmonary arteries) a deep maroon
or reddish-black color.

It constitutes about Vi - or 1/u of the body-weight, an. I con-
sists <-f the Liquor sanguinis and the corpuscles, red, white, etc.
The red corpuscles or erythrocytes are elastic, specific
gravity L088, Don-nucleated, and average about Hooo "M "'
diameter. A cubic millimeter of blood contains, m the male.
5,000,000 red blood-cells, and, in the female, 4,500,000. On
evaporation they become stellate, and swell up with water. They
vary much in size and Bhape in differenl animals, and contain
hemoglobin, which carries oxygen to the tissues an. I C02 to the
bin.

Clot.

176 HUMAN ANATOMY.

The colorless corpuscles or leucocytes are free nucleated
protoplasmic masses, capable of ameboid movement. They con-
tain fat-corpuscles, myosin, cholesterin, protagon, glycogen and
nuclein. There is about 1 white corpuscle to every 600 red
corpuscles, or in 1 cubic millimeter of blood there are present
about from 5000 to 10,000 white corpuscles, an average of 7500.
According to Ehrlich and others, by means of a "tri-acid stain,"
five varieties of colorless cells may be distinguished as fol-
lows : —

1. Small lymphocytes,

2. Large lymphocytes or mononuclear leucocytes,

3. Transitional leucocytes,

4. Polymorphonuclear leucocytes, and

5. Eosinophiles.

The liquor sanguinis is a pale, amber-colored fluid, holding
the corpuscles in suspension, and very prone to coagulate. The
coagulation of the blood results in the formation of a clot, or
crassamentum, and the serum, in the following manner : —

C Cornuscles / White corPuscles
corpuscles, j Red corpuacle8-

Fluid blood J ,,,

I P1fsma°r 1 Fibrin.

! eLl(luor \ Serum. J-Q

i Sanguinis J berum.

THE CIRCULATION OP THE BLOOD.

Fetal Circulation. — The fresh arterial blood returning from
the placenta through the umbilical vein enters the fetus at the
umbilicus, passes along the suspensory ligament to the under
surface of the liver, where a portion passes directly into the
inferior vena cava by the junction of the ductus venosus with
the left hepatic vein, a portion enters the liver and reaches the
inferior vena cava through the hepatic veins, and the larger por-
tion mixes with the portal venous blood before reaching the vena
cava through the hepatic veins. It ascends in the inferior vena
cava along with the venous blood from the trunk and lower
extremities to enter the right auricle of the heart (Fig. 78).
Here it is directed by the Eustachian valve through the foramen
ovale into the left auricle, into the left ventricle, and so through
the aorta, chiefly to the head and upper extremities, a small por-
tion only entering the descending aorta. It is returned by the
superior vena cava to the right auricle, passes over the Eu-
stachian valve to the right ventricle, and so through the pulmo-
nary artery toward the lungs, but (the lungs being almost

THE HEART AND VASCULAR SYSTEM.

177

Fig. 78.

Diagram of the fetal circulation: 1, umbilical cord, with veins and arteries;
2, placenta; :', divisions of umbilical vein; 4, hepatic branches; 5, ductus
venosus; 6. inferior vena cava; 7, portal vein; 8, right auricle; 9, left auricle;
10, left ventricle; 11, arch of aorta; 14, superior vena cava; 15, right ventricle;
10, pulmonary artery; 17, ductus arteriosus; 18, descending aorta; 19, umbilical
arteries.

12

178 HUMAN ANATOMY.

impervious) most of it passes through the ductus arteriosus into
the descending aorta (mixing with the small quantity from the
left ventricle before mentioned) to supply the lower extremities,
abdominal and pelvic viscera, and as venous blood to return
through the umbilical arteries to the placenta.

Circulation After Birth and in Adult. — The dark venous
blood from the entire body is received through the superior and
inferior venae cavse and coronary sinus into the right auricle,
whence it passes into the right ventricle, to be sent through
the pulmonary artery into the lungs. Here it becomes oxygen-
ated, and as bright arterial blood it returns to the left auricle
by the pulmonary veins, and passes into the left ventricle,
whence it is distributed through the aorta and its branches to
the entire body.

AORTA (ARTERIA MAGNA ) .

This is the main trunk of the systemic arteries. Com-
mencing at the upper part of the left ventricle, it ascends for
a short distance, arches backward over the right pulmonary
artery, the root of the left lung, to the left side of the body of
the fourth dorsal vertebra, where it passes downward through
the diaphragm and becomes the abdominal aorta. It then
descends to the lower border of the fourth lumbar vertebra,
where it terminates by dividing into the left and right common
iliac arteries. In its course it is divided into the arch, the
thoracic aorta, and the abdominal aorta, the arch being sub-
divided into the ascending, transverse and descending portion.

Relations. — The ascending portion of the arch is in relation on the
right side with the superior cava and right auricle; on the left side
with the pulmonary artery; in front, with the pulmonary artery, the
pericardium, the right appendix auriculae and the thymus gland; and
behind, with the root of the right lung and the right pulmonary vessels.

The transverse portion of the arch is in relation in front with the
left lung and pleura, the left pneumogastric and phrenic nerves, the
superficial cardiac nerves, the left superior intercostal vein, and the
thymus gland; behind, with the trachea, the esophagus, the thoracic
duct, the deep cardiac plexus, and the left recurrent nerve; above, with
the arteria innominata, the left innominate vein, the left subclavian,
and the left carotid; and below, with the left bronchus, the bifurcation
of the pulmonary artery, the left recurrent nerve, and the remains of
the ductus arteriosus.

The descending portion of the arch is in relation in front with the
root of the left lung and the pleura ; behind, with the left side of the
body of the fifth dorsal vertebra; on the right side with the thoracic
duct and esophagus; and on the left side with the pleura.

THE HEART AND VASCULAE SYSTEM. 179

The branches of the aorta are, from the arch: —

Two coronary, Left common carotid.

Innominate, Left subclavian.

The coronary arteries supply the heart and are two in
number — the right and the left (a. coronaria cordis dextra et

sinistra). The right arises from the aorta, above the right semi-
lunar valve, and passes downward in a groove between the right
auricle and ventricle on its posterior surface, dividing into two
branches, one of which anastomoses with the left coronary. The
left coronary arises above the left semilunar valve and descends
in the anterior interventricular groove, where it divides into
two branches, one of which anastomoses with the right coronary.
Arteria Innominata (a. anonyma). — This is the largest
branch from the arch of the aorta. It ascends to the upper
border of the right sternoclavicular articulation, where it divides,
into the right common carotid and the right subclavian arteries.
It is a short vessel, from one and a half to two inches long.

Relations. — It is in relation in front with the sternum, the sterno-
hyoid and sternothyroid muscles, the left innominate and right inferior
thyroid veins, the thymus gland, and the cardiac branch from the right
pneumogastric ; behind, with the trachea; on the right side, with the
pleura and right vena innominata and right pneumogastric nerve; on
the left side, with the left carotid and the thymus gland.

The Common Carotid Arteeies (a. carotis communis) . —
The left common carotid, arising directly from the arch of the
aorta, is longer and ascends more obliquely and is more deeply
placed than the right.

From the sternoclavicular articulation to their division at
the upper border of the thyroid cartilage the common carotid on
either side pursues the same course. At the lower part of the
neck the two vessels are separated by a very short interval,
which is occupied by the trachea, but at the upper part they
diverge widely; the larynx, pharynx, thyroid body, and several
muscles being interposed between them. It ascends the neck in
a direction indicated by a line drawn from the sternoclavicular
articulation to midway between the mastoid process and the
angle of the lower jaw.

Relations. —It is in relation in front with the sternomastoid,

sternothyroid, sternohyoid and omohyoid scles, the anterior jugular

and the superior ami middle thyroid veins, the sternohyoid artery, and
the descendens and communicans noni nerves; behind ii rests upon the
longus colli and rectus e;i|>iii> anticus major muscles and is in relation
with the sympathetic nerve, the recurrent laryngeal nerve, and the
inferior thyroid artery; on the Outer side, with the pneumogastric and

180 HUMAN ANATOMY.

the internal jugular vein; to the inner side, the larynx, trachea, pharynx,
thyroid gland, inferior thyroid artery and the recurrent laryngeal
nerve.

THE EXTERNAL CAROTID ARTERY (A. CAROTIS EXTERNA).

From its commencement at the superior border of the thy-
roid cartilage it passes upward and forward and then backward,
beneath the anterior margin of the sternomastoid muscle, in a
direction indicated by an imaginary line drawn from the supe-
rior border of the thyroid cartilage to a point midway between
the meatus and the neck of the condyle of the lower jaw. It
ascends through the space known as the superior triangle of the
neck.

Relations. — It is in relation in front with the parotid gland and
the facial nerve and tempo romaxillary vein passing through it, covered
by the skin, superficial fascia, platysma, and deep fascia, and is crossed
by the digastric and stylohyoid muscles, hypoglossal nerve, lingual and
facial veins; behind it is separated from the internal carotid by the
parotid gland, styloglossus and stylopharyngeus muscles, and the glosso-
pharyngeal nerve, and at its lower part the superior laryngeal nerve
ascends behind it; to its inner side it is in relation with the pharynx,
hyoid bone, superior laryngeal nerve, and the ramus of the lower jaw,
from which it is separated by the parotid gland.

The branches of the external carotid are eight: —

1. Superior thyroid, 5. Posterior auricular,

2. Lingual, 6. Ascending pharyngeal,

3. Facial, 7. Temporal,

4. Occipital, 8. Internal maxillary.

1. Superior thyroid (a. thyreoidea superior) arises below
the great cornu of the hyoid bone, passes beneath the sterno-
hyoid, omohyoid and sternothyroid muscles to the upper part
of the thyroid gland, where its terminal branches anastomose
with its fellow of the opposite side. Its branches are : —

(a) Hyoid (ramus hyoideus) , to the lower border of the hyoid
bone ;

(b) Superficial descending branch {ramus sternocleidomastoideus) ,
crosses the common carotid artery to supply the skin and sternomas-
toid muscle;

(c) Superior laryngeal (a. laryngea superior), passes beneath the
thyrohyoid muscle with the superior laryngeal nerve;

(d) Cricothyroid (ramus cricothyreoideus) , crosses the crico-
thyroid membrane.

2. The lingual artery (a. lin gualis) arises from the ante-
rior part of the external carotid, between the superior thyroid
and the facial. It passes inward and upward to the greater

THE HEART AND VASCULAR SYSTEM. 181

cornu of the hyoid bone, and, descending, reaches the under
surface of the tongue and runs along its under surface as far
as its tip, where it terminates as the ranine.

In its course it passes through a triangle hounded on two
sides below by the two bellies of the digastric, and above by the
hypoglossal nerve, passing under the hyoglossus muscle. Its
branches are : —

Hyoid (ramus hyoideus) , to the hyoid bone;

Dorsalis linguae (ramus darsalis Ungucc), supplies the epiglottis,
soft palate, tonsil, and the mucous membrane of tongue;

Sublingual (a. sublingualis), supplies mylohyoid and geniohyo-
glossus muscles and sublingual gland;

Ranine (a. profunda, lingua'), the terminal branch, ends at the
tip of the tongue.

3. The facial artery (a. ma.villaris externa) arises from
the anterior portion of the external carotid artery above the
lingual. It ascends forward through the submaxillary gland,
crosses the lower jaw at the anterior border of the masseter
muscle, and crosses the cheek to the angle of the mouth and
the side of the nose, where it terminates as the angular artery
(a. angularis). Its branches in the neck are: —

Inferior or ascending palatine (a. palatine ascendens) , supplies
the soft palate, palatine glands, tonsil and Eustachian tube;

Tonsillar (ramus tonsillaris), supplies the root of the tongue
and tonsil;

Submaxillary {rami glandular es) , supplies the submaxillary
gland and neighboring lymphatics, muscles, and skin;

Submental [a. submentalis ) , supplies the chin, lower lip and
neighboring structures;

Muscular, to the buccinator, masseter and internal pterygoid
muscles.

In the face: —

Muscular, to the same muscles as given above;

Inferior labial (a. labiaMs inferior), to the skin of the lower lip;

Inferior coronary, to the mucous membrane, muscles and glands
of the lower lip;

Superior coronary (a. labialis superior), to the structures of the
Upper lip and nasal septum;

Lateralis nasi, to the skin of the nostrils, anastomoses with the
nasal branch of ophthalmic;

Angular I", angularis), supplies lachrymal sac and skin. All of
these branches anastomose freely with the neighboring arteries.

4. The occipital artehy (a. arteria occipitalis) arises
from the posterior portion of the external carotid, about tin'
lower border of the digastric muscle. It passes beneath the
stylohyoid muscle, the digastric muscle, and part of the parotid

182

HUMAN ANATOMY.

gland, and, ascending, grooves the internal surface of the mas-
toid portion of the temporal bone and distributes itself over the
occiput as high as the vertex. Its branches are : —

Muscular (rami musculares) , to splenius, digastric, stylohyoid,
etc;

Sternomastoid (a. stemocleidomastoidea) , crosses the hypoglossal
to the sternomastoid muscle;

Auricular (ramus auricularis) , is distributed to the back part
of the concha;

12 10

Pig. 79.

Arteries of face and head: 1, common carotid; 2, internal carotid;
3, external carotid; 4, occipital; 5, superior thyroid; 7, lingual; 9,
facial; 10, temporal; 11, submental; 12, transverse facial; 13, infe-
rior labial; 15, 17, inferior and superior coronary; 19, lateral nasal;
21, angular.

Meningeal (ramus meningeus) , passes through the foramen
lacerum posterius to the dura mater;

Arteria princeps cervicis ( ramus descendens ) . Its superficial
branch anastomoses with the superficial cervical, and its deep branch
with the deep cervical branch from the superor intercostal.

THE HEART AND VASCULAB SYSTEM. ^3

Cranial branches are distributed to the scalp over the
occiput.

5. The posterior auricular artery (a. auric ularis pos-
terior) arises from the posterior portion of the external carotid,
on a level with the apex of the styloid process. It ascends
beneath the parotid gland to a point between the mastoid process
and the cartilage of the ear, where it divides into two branches,
one going to the ear and the other to the occiput. Its branches
are: —

Stylomastoid (a. stylomasioidea) , supplies the mastoid cells,
tympanum and semicircular canals, entering the cranium through the
stylomastoid foramen;

Auricular (ramus am inilaris ) , supplies the cartilage of the ear;

Muscular, supply the sternomastoid, digastric and stylohyoid
muscles;

Glandular, to parotid gland.

C. The ASCENDING PHARYNGEAL ARTERY (a. pharyngea OS-

cendens) arises about the commencement of the external carotid
artery and ascends to the base of the skull upon the rectus
capitis antieus major. Its branches are: —

Pharyngeal (rami pharyngei), supplies the three constrictors of
the pharynx and the stylopharyngeus muscles;

External, to the neighboring muscles, glands, and hypoglossal and
pneumogastric nerves;

Meningeal, enter the skull through the posterior and middle lacer-
ated foramina and the anterior condyloid foramen.

7. The superficial temporal artery (a. temporalis su-
perficialis) is the smaller of the two terminal branches. It
arises in the parotid gland, crosses the root of the zvgoma,
ascends forward a couple of inches, and divides into the anterior
temporal and the posterior temporal. Its branches are: —

Transverse facial (a. transversa faciei), supplies the masseter
muscle, parotid gland and skin;

Middle temporal (a. temporalis media), crosses the face to supply
the temporal muscle and fascia;

Anterior auricular (rami auriculwres anteriorcs) , supplies the
lobule, external meatus and front part of pinna.

The ENTEENAL maxillary (a. maxillaris in tenia) is the
larger of the two terminal branches of the external carotid. It
arises in the parotid gland about the level of the lower part of
the lobe of the car. passing close to the inner side of the m
of the condyle of the lower jaw to be distributed to the deep
structures of the face. Its course is divided into three portions:
the maxillary portion, passing inward and forward between the

184

HUMAN ANATOMY.

internal lateral ligament and the ramus of the jaw; the ptery-
goid portion, passing upward and forward upon the external
pterygoid muscle; and the third part, or sphenomaxillary, enters
the sphenomaxillary fossa. Its branches are, from the maxillary
portion : —

Tympanic (anterior) (a. tympanica anterior), supplies the tym-
panum through the Glaserian fissure, forming a capillary plexus on the
tympanic membrane;

Middle meningeal ( a. meningea media ) , enters the cranium
through the foramen spinosum, supplies the dura mater, and gives off

Fig. 80.

Internal maxillary artery: A, third portion; B, second portion; C,
first portilon.

a petrosal branch (ramus petrosus super ficialis) to facial nerve in
hiatus Fallopii;

Small meningeal (ramus meningeus accessorius) , or meningea
parva, enters foramen ovale to supply dura mater and Gasserian
ganglion ;

Inferior dental (a. alveolaris inferior), accompanies the dental
nerve through the inferior dental canal to the mental foramen, supply-
ing the jawbone, teeth, chin and mouth.

The pterygoid portion : —

Deep temporal (aa. temporalis profunda anterior et posterior),
supply the temporal muscle;

Pterygoid (rami pterygoidei) , to pterygoid muscles;
Masseteric (a. masseterica) , to the masseter muscle;
Buccal (a. ljuccinatoria) , to the buccinator muscle.

POSTEROMEDIAN GANGLIONIC

POSTERIOR TEM1VRAI
ANTERIOR TEMPORAL
SUPERFICIAL TEMPORAL
ANTERIOR AURICULAS
MIDDLE TEMPORAL
ORBITAL

Po-TERIOR AURICULAR
INTERNAL MAXILLARY
ARTERU PRINCEPS CERV1CIS
OCCIPITAL
SUP BR. PRINCEPS CERVICIS'
DEEP BR. PRINCEPS CERVICIS
ASCENDING CERVICAL
DEEP CERVICAL
SUPERFICIAL CERVICAL
SUPRASCAPULAR
R. SUBCLAVIAN
POST SCAPULAF

SUP \ ENA CAVA

B. PULMONARY A
R I'l I.MONARV VEIN
R AUBICLE

• '.AKY
INK VENA CAVA
IHOBACII AORTA

ANTERIOR _CI IMMUNICATING
ANTERIOR
CEREBRAL —

MIDDLE CEREBRAL "

OPHTHALMIC .

TEMPORAL .

POST COMMUNICATING

POST CEREBRAL -

SUPERIOB CEREBELLAR.

SUP STERN0-MAST0ID.

BASILAR -
ANT. INFERIOR
CEREBELLAR -

L. INT CAROTID .
FACIAL _

FIG. 81.

'I'lio art'Tiis o!' the head and neck,

THE HEART AND VASCULAR SYSTEM. 185

Sphenomaxillary portion : —

Alveolar or posterior dental branch (a. aheolaris superior poste-
rior), supplies the upper molar and bicuspid teeth, antrum and gums;
its principal branch is the superior dental;

Infraorbital (a. infraorbitaUs) , passes through infraorbital canal
to face:

Posterior or descending palatine («. palatina descendens),
descends posterior palatine canal and runs forward to foramen of
St<'iison;

Vidian (or. canalis pterygoidea) , accompanies the Vidian nerve;

Pterygopalatine, supplies Eustachian tube and pharynx;

Nasal, or sphenopalatine (a. sphenopalatine/,), descends through
sphenopalatine foramen to antrum, sphenoidal and ethmoidal cells.

THE INTERNAL CAROTID ARTERY (A. CAROTIS INTERNA)

arises about the upper border of the thyroid cartilage from the
bifurcation of the common carotid. It ascends in front of the
transverse processes of the cervical vertebrae to the carotid fora-
men in the petrous portion of the temporal bone to supply the
anterior part of the brain, the eye with its appendages, and send
branches to the nose and forehead. It gives no branches until
it passes through the carotid canal, where, after piercing the
dura mater at the anterior clinoid process, it divides into its
terminal branches — the anterior and middle cerebral.

Relations. — The internal carotid artery in the neck is in relation
in front with the parotid gland, the glossopharyngeal nerve, the stylo-
glossus and stylopharyngeal muscles, and is covered by the skin, super-
ficial and deep fascia'; behind it rests upon the rectus capitis anticus
major and has resting upon it the superior laryngeal nerve and the
sympathetic; internally it is in relation with the pharynx, tonsil,
superior laryngeal nerve and descending pharyngeal artery; externally
ii is in relation with the internal jugular vein and the pneumogastric
nerve.

Its branches arc, from the petrous portion: — ■

Tympanic, internal or deep [ramus caroticotympamcus) , sup-
plies tympanum.

From the cavernous portion : —

Artiriiv rrr-< [ttaciili, supply the Gasserian ganglion and pituitary
body;

Anterior meningeal ('/. menigea anterior), a branch from the pre-
oeding v—el to the dura.

Ophthalmic ('/. ophthalmica) arises about tbe position of
the anterior clinoid process and passes through the optic fora-
men to the outer side of tin- optic ner\e jo reach the orbit. At
the inner angle of the eye it divides into its two terminal

186 HUMAN ANATOMY.

branches — the frontal and the nasal. It supplies the muscles
and the globe of the eye, and its branches may be divided into
two groups — the orbital and the ocular.
Orbital group : —

Lachrymal (a. laohrimaUs) , supplies the lachrymal gland and
gives off a malar branch which passes through the malar bone to the
temporal fossa;

Supraorbital (a. supraorbitals) , passes out through the supra-
orbital foramen to supply the surrounding structures;

Posterior ethmoidal (a. ethmoidalis jjosterior) , descends through
the posterior ethmoidal foramen to the cells and adjacent parts;

Anterior ethmoidal (a. ethmoidalis anterior) } through the ante-
rior ethmoidal foramen to the nose;

Internal palpebral (aa. palpebrales mediales) , supply the eyelids.

Frontal (a,, frontalis), supplies the skin and muscles of the fore-
head.

Nasal (a. dorsalis nasi), supplies the lachrymal sac and bridge of
the nose.

Ocular group : —

Muscular, supply the muscles of the eye;

Anterior ciliary {aa. ciliares anteriores) , supply the iris, piercing
the sclerotic near the cornea ;

Short ciliary (aa. ciliaris posteriores breves), supply the choroid
and ciliary processes, piercing the sclerotic near the optic nerve;

Long ciliary (aa. ciliares posteriores longw), enter with the short
ciliary, but run forward to the iris;

Arteria centralis retinae, supplies the optic nerve and the retina.

From the cerebral portion : —

Anterior cerebral (a. cerebri anterior), supplies the ante-
rior part of the cerebrum, the optic and olfactory nerves, and com-
municates with its fellow by the anterior communicating;

Middle cerebral, or Sylvian artery ( a. cerebri media ) , ascends in
the Sylvian fissure, and supplies the middle lobes of the cerebrum;

Posterior communicating (a. communicans posterior) , runs back-
ward to join the posterior cerebral;

Anterior choroid (a. choroidea) , supplies the choroid plexus.

THE CIRCLE OF WILLIS (CIRCULUS ARTERIOSUS [wiLLISl] )

is an anastomotic circle formed at the base of the brain about
the pituitary body, between the branches of the internal carotid
and the vertebral arteries, for the purpose of equalizing the
cerebral circulation. The anterior cerebrals, from the internal
carotids, pass forward and are united in front by a short trunk,
the anterior communicating. The posterior communicating
unites the internal carotid with the posterior cerebral, the latter
being the terminal branches of the basilar, which in its turn
is formed by the union of the two vertebrals.

Acromial thoracic

M fl KJ"H I HoRai |c

LONG THORACIC

HAUIAI. ISDICIB

nL^K PALMAH DIGITALS

Fig. 82.
The arteries of thr» upper extremity.

THE HEART AND VASCULAR SYSTEM. 18?

TIIK SUB< LAVIAX AKTERY (A. srBCLAVIA)

on the right side arises from the arteria innominata, hehind the
right sternoclavicular articulation, and on the left side directly
from the arch of the aorta. They pass outward to the outer
margin of the first rib, where they become the axillary, being
divided in their course by the scalenus anticus muscle into three
portions — the first portion to the inner side of the muscle, sec-
ond portion behind it, and the third portion between its outer
margin and the lower border of the first rib. The vessels differ
only in their first portions, the left ascending more vertically.

Relation The first portion of the right subclavian is in relation

in front to the internal jugular and vertebral veins, the sternohyoid and
sternothyroid and the clavicular portion of the sternomastoid muscles
and the* pneumogastric, phrenic, and cardiac nerves; behind it is in
relation with the longus colli muscle, the transverse process of the
first dorsal or seventh cervical vertebrae, the sympathetic nerve, and
the recurrent laryngeal nerve beneath with the pleura.

The first portion of the left subclavian artery is in relation in
front with the left internal jugular and innominate veins, the left
carotid artery, the sternothyroid, sternohyoid, and sternomastoid
muscles, the "pleura and left lung, the pneumogastric, phrenic and
cardiac nerves; behind, with the vertebral column and longus colli
muscle, the esophagus, thoracic duct, and the inferior cervical
ganglion of the sympathetic; on the inner side with the esophagus,
thoracic duct, and trachea, and on the outer side with the pleura. The
second portion of the subclavian artery on either side is in relation with
the subclavian vein, the scalenus anticus muscle and the phrenic
nerve; behind with the middle scalenus muscle and pleura; above by
brachial plexus, and below by the pleura. The third portion of the
subclavian artery on either side is in relation in front with the exter-
nal jugular vein and its branches, the clavicle, subclavius muscle and
suprascapular artery, the descending branches of the cervical plexus
and the cervical fascia; behind with the scalenus medius, above with
the omohyoid muscle and the brachial plexus, and below with the first
rib.

[te branches are: —

1. Vertebra] i". oertebraUs) . 5. Transverse cervical, or

2. Thyroid axis [truncus thy- transversal is colli (a.

1 1 <>c< i rifiilis) . transversa colli).

:;. Inferior thyroid (a. thy- 0. Internal mammary (a.
/■<',»/<</ inferior). mammaria interna).

4. Suprascapular [a. trans- 7. Superior intercostal [trim-
versa 8cajnilrp). cm oostocervioalis).

These branches are all given off from the first portion.
pi the Buperior intercostal, which arises on the right side,
from the second portion.

188 HUMAN ANATOMY.

1. The vertebral artery (a. vertebralis) passes upward,
enters the foramen in the transverse process of the sixth cervical
vertebra, and ascends through the foramina until it reaches the
atlas, when it runs backward, pierces the posterior occipito-
atloid ligament and dura mater to enter the skull through the
foramen magnum. After entering the cranium it passes for-
ward to the lower border of the pons Varolii where it unites
with its fellow of the opposite side to form the basilar artery.
Its branches are —

. Cervical branches : —

Lateral spinal (rami spinales) , supply the spinal cord and its
membranes, entering the spinal canal through the intervertebral
foramina;

Muscular, supply the deep muscles of the neck.

Cranial branches: —

Posterior meningeal (ramus meningeus) supply the falx cerebelli ;

Anterior spinal (a. spinalis anterior), supplies the cord; uniting
with branches from the inferior thyroid, intercostals, and lateral sacral,
descend to the cauda equina;

Posterior spinal (a. spinalis posterior), descends in the same
manner as the anterior;

Posterior inferior cerebellar (a. cerebelli inferior posterior) , sup-
plies the inferior surface of the cerebellum and the choroid plexus of
the fourth ventricle.

The branches of the basilar artery (a. hasilaris) are: —

Transverse (rami ad pontem), to the pons Varolii and inferior
surface of the cerebellum;

Anterior inferior cerebellar (a. cerebelli inferior anterior), a
branch of the transverse;

Superior cerebellar (a. cerebelli superior), supplies pia mater,
pineal gland and velum interpositum.

Posterior cerebral (a. cerebri posterior'), to posterior lobes of
cerebrum and choroid plexus.

2. The thyroid axis {truncus tliyreocervicalis) consists of
three branches — the inferior thyroid, the suprascapular and the
transversalis colli.

3. The inferior thyroid artery (a. thyreoid 'ea inferior) is
distributed to the thyroid gland, its branches being: —

Inferior laryngeal (a. laryngea inferior), to muscles and mucous
membrane of larynx;

Tracheal (rami tracheales) , to the trachea, anastomosing with the
bronchial arteries;

Esophageal (rami cesophagei) , to esophagus;

Ascending cervical ( a, cervicalis ascendens ) , supplies the spinal
cord and membranes, vertebrae, and muscles of neighborhood;

Muscular (rami muscular e s) , to inferior constrictor of pharynx,
scalenus anticus, and other muscles.

THE HEART AND VASCULAR SYSTEM. 189

-i. The suprascapular artery — transversal is humeri (a.
transversa scapula) passes beneath the posterior belly of the
omohyoid to the upper border of the scapula, passing over the
transverse ligament of the scapula to the supraspinous fossa,
where it is distributed to the supraspinatus, sternomastoid, and
other muscles, and by means of the supra-acromial branch to
the skin over the acromion, anastomosing with the posterior
circumflex and acromial thoracic arteries.

In about 50 per cent, of bodies tbis artery will be found to arise
from tbe third portion of tbe subclavian.

5. The transversalis colli (a. transversa colli) passes out-
ward to the trapezius muscle, where it divides into

The (a) superficial cervical (ramus ascendens), an important
branch passing beneath the trapezius to anastomose with the superficial
branch of the arteria princeps cervieis;

And the (b) superficial posterior scapular (ramus descendens),
the larger passing to and along the upper and posterior border of the
scapula, beneath the levator anguli scapulae, rhomboidei, latissimus
dorsi and trapezius, to anastomose with the subscapular, suprascapular,
and posterior branches of the interoostals.

G. The internal mammary (a. mammar'm interna) arises
from the subclavian, opposite the thyroid axis, and descends
upon the internal surfaces of the costal cartilages to a point
in the sixth intercostal space, where it divides into the musculo-
phrenic and the superior epigastric. Its branches are: —

Tomes nervi phrenici — superior phrenic (a. pericardiacophrenica) ,
supplies diaphragm, passing between the pleura and pericardium;

Mediastinal (aa. mediastinalrs ante) iores) , to the anterior
mediastinum ;

Pericardiac, to upper portion of pericardium;

Sternal (rami 8ti males) , to posterior surface of sternum;

Anterior intercostal (rami inter cost ales) , to fifth or sixth upper
intercostal spaces;

Perforating (rami perforantes) , perforate the intercostal spaces
to Bupply the mammary gland;

Musculophrenic (a. musculophrenica) , supplies lower part of peri-
cardium, diaphragm, and upper part of abdominal muscles;

Superior epigastric (a. epigastrica superior), supplies the rectus
muscle, and anastomoses with the deep epigastric from the external
iliac.

7. The superior intercostal artery (truncus costocervicalis)

arises from the subclavian, behind the anterior scalenus muscle,

and descends behind the pleura and anastomoses with the firsi
aortic intercostal artery. It gives off branches in the intercostal

190 HUMAN ANATOMY.

spaces to the spinal cord and its membranes and the posterior
spinal muscles. Its principal branch is the deep cervical (pro-
funda cervicis).

THE AXILLARY ARTERY (A. AXILLARIS)

is the continuation of the subclavian, extending outward from
the lower edge of the first rib to the lower margin of latissimus
dorsi and teres major muscles, where it becomes the brachial.
It is divided by the pectoralis minor into three parts — the first
portion above, the second portion behind, and the third portion
below that muscle. It passes through the space known as the
axilla (vide Regions).

Relations. — First portion: The first portion of the axillary is in
relation in front with the subclavius and pectoralis major muscles,
costocoracoid membrane, acromial thoracic and cephalic veins and the
external anterior thoracic nerve; the axillary vein to its inner side,
the brachial plexus to its outer side, and the posterior thoracic nerve
and serratus magnus behind. Second portion: The relations of the
second portion are niuch the same as the first, with the addition of the
pectoralis minor in front and the division of the brachial plexus sur-
rounding the vessels. Third portion: The third portion is in relation in
front with the inner head of the median nerve and the pectoralis major
muscle; to the inner side with the axillary vein, internal cutaneous and
ulnar nerves; to the outer side, the median and musculocutaneous
nerves and coraeobrachialis muscle; and, behind, the circumflex and
musculospiral nerves and the subscapulars, latissimus dorsi and teres
major muscles.

Its branches are: —

Superior thoracic (a. thoracalis supremo), supplies the
pectoralis major and minor muscles;

Acromial thoracic (a. thoracoacromialis) , gives off three
branches — acromial, thoracic and descending, supplying the
pectoralis major and minor, serratus and deltoid;

Long thoracic (a. thoracalis lateralis), follows the lower
border of the pectoralis minor to supply the serratus, pectoralis
major and minor, and mammary glands;

Alar thoracic supplies the axillary glands;

Subscapular (a. subscapulars), arises from the axillary
artery about the level of the lower border of the subscapularis
muscle. It passes backward and downward to the inferior dor-
sum of the scapula. Its branches anastomose with the posterior
scapular and the suprascapular. They are : —

Subscapular (a. subscapularis) , supplies the subscapularis muscle;

Dorsalis scapulae (a. circurnflexa scapula'), is distributed to the
infraspinous fossa, anastomosing with the posterior scapular and supra-
scapular arteries;

THE HEART AND VASCULAR SYSTEM. 191

Median branch, descends the axillary border of the scapula to
supply teres muscles.

Posterior circumflex (a. circumfiexa> humeri posterior), en-
circles the neck of the humerus to supply the shoulder joint and
the deltoid muscle;

Anterior circumflex (a. circumfiexa humeri anterior), de-
scends beneath the short head of biceps and coracobrachial
muscles to supply the shoulder joint.

THE BRACHIAL ARTERY (A. BRACHIALIS)

commences at the lower border of the latissimus dorsi and teres
major muscles and descends on the front and inner aspect of
the arm to half an inch below the middle of a line drawn
through the condyles of the humerus, where it terminates by
dividing into the radial and ulnar artery.

Relations. — It is covered in front by the skin, superficial and deep
fascia, and is crossed by the median nerve; behind it rests upon the
triceps, brachialis anticus and coracobrachial muscles;

And is in relation with the musculospiral nerve and the superior
profunda artery ; to the outer side above it is in relation with the
biceps and coracobrachialis muscles and the median nerve; and on
the inner side with the internal cutaneous and ulnar nerve, and the
basilic vein and median nerve below.

At the bend of the elbow it is crossed by the bicipital fascia.
Its branches are: —

-Superior profunda (a. profunda brachii), accompanies the
musculospiral nerve to supply the triceps, deltoid and coraco-
brachialis muscles;

Nutrient artery (a. nutricia humeri), supplies the shaft of
the humerus;

Inferior profunda {a. eollateralis ulnaris superior), accom-
panies the ulnar nerve to supply the triceps muscle and struc-
tures about the internal condyle ;

Anastomotica magna (a. eollateralis ulnaris inferior),
forme as anastomosis on the lower posterior aspect of the arm,
with branches from the inferior profunda and recurrent ulnar
-'.•Is. It supplies the triceps;

Muscular (rami iinisiiilares), supply the muscles on the
anterior aspect of the arm.

THE BADIAL ARTERY (A. RADIALIS)

:ds from the bifurcation of the brachial below the bend
of the elbow to the wrist, where it winds around the carpus

192 HUMAN ANATOMY.

beneath the extensor tendons of the thumb, passes between the
two heads of the first dorsal interosseous muscle and into the
palm of the hand, where it forms the deep palmar arch, anasto-
mosing with the deep branch of the ulnar artery. Its branches
are, in the forearm : —

Radial recurrent (a. recurrens radialis) , supplies the braehialis
anticus and supinator longus and brevis;

Muscular {rami musculares) , supply the radial muscles;

Superficialis volse (ramus volaris superficialis) , supplies the
muscles of the thumb and anastomoses with the ulnar to form the
superficial palmar arch;

Anterior radial carpal (ramus carpeus volaris), supplies the
wrist-joint.

In the wrist: —

Posterior radial carpal (ramus carpeus dorsalis) , supplies the
wrist-joint, forms the posterior carpal arch, and gives off the dorsal
interosseous arteries;

Metacarpal, is called the first dorsal interosseous; it supplies the
index and middle finger;

Dorsales pollicis, supply the back of the thumb;

Dorsalis indicis, supplies the outer and dorsal side of the index
finger.

In the hand: —

Princeps pollicis (a. princeps pollicis), supplies the sides of the
palmar aspect of the thumb;

Radialis indicis (a. volaris indicis radialis), supplies the radial
side of index finger;

Perforating (rami perf or antes) , anastomose with dorsal interos-
seous arteries;

Interosseous (aa. metacarpew volares) , anastomose with digital
branches of superficial palmar arch.

THE ULNAR ARTERY (A. ULNARIS)

descends from the bifurcation of the brachial below the bend
of the elbow to the ulnar border of the wrist, passing beneath
all the superficial flexors excepting the flexor carpi ulnaris,
crosses over the annular ligament at the radial side of pisiform
bone, and enters the palm to form the superficial palmar arch,
anastomosing with the superficialis volse from the radial. Its
branches are, in the forearm : —

Anterior ulnar recurrent (a. recurrentes ulnaris anterior), sup-
plies the pronator radii teres and braehialis anticus muscles;

Posterior ulnar recurrent (a. recurrentes ulnaris posterior), sup-
plies the joint and neighboring muscles, and anastomoses freely;

Interosseous (a. interossea communis), passes backward to the
upper border of the interosseous membrane, where it divides into

THE HEART AND VASCULAR SYSTEM.

193

Anterior branch (a. mterossea volaris), descends on the front of
the interosseous membrane;

Posterior (a. intcrossea dorsalis) , descends on the posterior as-
pect of the foramen and gives off a recurrent interosseous branch-

Muscular {rami musculares), to muscles on ulnar side of forearm.

In the wrist: —

Anterior carpal (ramus carpeus volaris), supplies the front of
wrist and anastomoses with the carpal branches of radial artery-

Posterior carpal (ramus carpeus dorsalis), passes beneath the ten-
don ot flexor carpi ulnaris and forms posterior carpal branch.

In the hand : —

Deep, or communicating branch (ramus volaris profundus) passes
between the flexor and abductor minimi digiti to form part of deen
palmar arch; * x

«i l« Dlgfi1tal',.!"Pply- the Ul!\a,r Skle of the little finSer and adjoining
sides of the little, ring, middle and index Angers.

THE DESCENDING AORTA.

The thoracic aorta (aorta thoracalis) extends from the
.wer border of the fifth dorsal vertebra on the left side to about
the last dorsal vertebra, where by passing through the aortic
opening m the diaphragm it becomes the abdominal aorta.

Relations— It is in relation in front with the left bronchus esoph-
agus pericardium and left pulmonary artery; behind it rests uj'xuxe
vertebral column and is ,n relation with the vena azygos minor; on the
right side it is m relation with the thoracic duct; the esophLms at
its upper part and the vena azygos major; on the left side with 'the
left lung, the pleura, and the esophagus below.

The branches of the thoracic aorta are :

Pericardiac (rami pericardiaci) , supply the pericardium-
Bronchial (aa. bronchioles), two or three in number, sup-
ply the bronchi ; ' l
Esophageal (aa. a> so phage®), supply the esophagus •
Posterior mediastinal (rami mediastinales) , supply the
neighboring pleura and lymphatic glands;

Intercostal (aa. intercostal es), ten on each side, supply the
intercostal spaces. They divide into— anterior branch, to inter-
costal and pectoral muscles; posterior branch, to spinal column
and dorsal muscles.

THE ABDOMINAL AORTA (AORTA ABDOMINALIS)

descends from the Inst dorsa] vertebra at the aortic opening of
the diaphragm, to opposite the fourth lumbar vertebra, a little

194 HUMAN ANATOMY.

to the left of the median line, where it divides into the two
common iliac arteries.

Relations. — Th" abdominal aorta is in relation in front with the
pancreas, transverse duodenum, stomach, and lesser omentum, the mes-
entery, splenic vein, left renal vein, celiac, solar and aortic plexuses;
behind, it is in relation with the vertebral column, the thoracic duct,
the left lumbar veins and the receptaculum chyli; on the right side
with the inferior vena cava, vena azygos, thoracic duct, the right crus
of the diaphragm above, and the right semilunar ganglion; on the left
side with the left semilunar ganglion and the sympathetic nerve.

The branches of the abdominal aorta are : —
Phrenic, two in number, supply the diaphragm;
Celiac axis (a. ccdiaca), divides into three large branches,
the gastric, hepatic and splenic;

1. Gastric, or coronaria ventriculi (a. gastrica sinistra), is
the smallest, and supplies the lesser curvature of the stomach ;

2. Hepatic (a. hepatica), enters the transverse fissure of
the liver, and divides into two branches to supply the lobes of
the liver. It gives off : —

Pyloric (a. gastrica dextra), to lesser curvature of stomach;

Gastroduodenalis, which descends behind the pylorus, and divides
into

Pancreaticoduodenalis superior branch to supply the pancreas and
duodenum ;

Gastroepiploica dextra, along the greater curvature of the
stomach from right to left.

Cystic ( a. cystica ) , supplies the gall-bladder.

3. Splenic (a. lienalis), the largest of the three, supplies
the spleen and gives off the

(a) Pancreatic (rami pancreatici) — to the pancreas;

(b) Gastroepiploica sinistra, runs from left to right, along the
greater curvature, to join the gastroepiploica dextra;

(c) Gastric — vasa brevia (aa. gmtricw brevis), supply the fun-
dus of the stomach.

Superior mesenteric (a. mesenterica superior), supplies the
small intestine (except first part of the duodenum) and the
large intestine as far as the splenic flexure, and part of the
descending colon. It gives off: —

(a) Inferior pancreaticoduodenal (a. pancreaticoduodenalis infe-
rior), supplies duodenum and pancreas;

(b) Vasa intestini tenuis (aa. intestinales) , supply nearly the
whole length of the small intestine (ileum and jejunum) ;

(c) Ileocolic (a. ileocolica) , descends to the right iliac fossa, be-
tween the layers of the mesentery, and divides into two branches;

(d) Right colic artery (colica dextra), passes to the middle of the
ascending colon, to divide into two branches;

THE HEART AND VASCULAR SYSTEM.

195

(«) Middle colic artery (colica media), ascends in the layers of
the transverse mesocolon, to divide into two branches.

Suprarenal (a. suparenalis media), supply the suprarenal
bodies ;

Renal (aa. renales), supply the kidneys, a large trunk on
each side springing directly from the aorta;

Spermatic (aa. spermatica} interna'), descend to supply the
testicles, and in their passage form one of the constituents of
the spermatic cord;

Fig. 83.

Abdominal aorta: 1, phrenic; 2, celiac axis; 3, superior mesen-
t« ri<- ; 4, suprarenal: 5, renal; G, spermatic; 7, inferior mesenteric;
8, lumbar; 9, sacra media.

Inferior mesenteric (aa. mesenterica inferior), gives off: —

(a) l.cfi colic [coUca amisira), supplies the descending colon;
3igmoid (aa. aigmoidece), supplies the sigmoid flexure of the
colon ;

(c) Superior hemorrhoidal (». h<r»i<>rrh<>i<l(ilis superior) , the con-
tinuation of tin- inferior mesenteric, supplies the mucous and muscular
coate "i the rectum <>n it- posterior aspect.

Lumbal branches («". Iwmbales), four or five on each side.
tackward and outward and divide into the

196 HUMAN ANATOMY.

Dorsal branches (rami dorsales), supply the spinal cord,
muscles, and skin of back ;

Spinal branches (rami spinales), divide within the spinal
canal, ascend and descend, and form an arterial network
throughout the whole length of the spinal canal;

Abdominal branches (rami parietales), supply the abdom-
inal walls;

Middle sacral (a. sacralis media), is the continuation of
the abdominal aorta, descending in the middle of the sacrum
to the upper part of the coccyx.

THE COMMON ILIAC ARTERIES (AA. ILIAC.E COMMUNES)

descend from the bifurcation of the abdominal aorta, opposite
the body of the fourth lumbar vertebra, to a point midway
between the last lumbar vertebra and the sacrum, where they
divide into the external and internal iliac arteries. The right
common iliac is a little larger than the left, and passes more
obliquely outward.

Relations. — The right common iliac is in relation in front with the
small intestine, the ureter, the peritoneum and the sympathetic nerves;
behind, with the left and right common iliac veins, and to its outer
side it rests upon the psoas musole, and is in relation with the vena
cava and the right common iliac vein. The left common iliac is in
relation in front with the ureter, the peritoneum, the superior hemor-
rhoidal artery and the sympathetic nerves; behind, with the left com-
mon iliac vein, to its outer side the psoas muscle, and to its inner side
the left common iliac vein.

The common iliac arteries give off a few unimportant
branches to the ureters, peritoneum, etc.

the internal iliac or hypogastric artery
(a. hypogastrica)

is about an inch and a half in length, extending from the bifur-
cation of the common iliac, about the sacrolumbar junction, to
the upper border of the great sacrosciatic foramen, where it
divides into the anterior and posterior trunks.

The branches from the anterior trunk are: —
Superior vesical (a. vesiculis superior), is the pervious
remains of the fetal hypogastric artery. It supplies the apex
and body of bladder, ureter and vas deferens;

Middle vesical (a. vesiculis medialis), supplies the base of
the bladder and part of vesiculae seminales ; it may be given off
from the superior vesical;

r jit. suprarenal
cystic

R. MID SUPRARENAL.
INK. PAXCREATICO DUODE.XAI
GASTRO-DUODEN U.
R. INF. SUPRARENAL
SUP PAXCREATICO DUODENAL.
R. GASTROEPIPLOIC
R. RENAL
MIDDLE COLIC
RIGHT COLIC
LUMBAR
SPERMATIC
ABDOMINAL AORTA
INF. MESENTERIC
MIDDLE SACRAL
R. COMMON ILIAC
SUP HEMORRHOIDAL
ILIO LUMBAR
R INT ILIAC
R. EXT. ILIAC
POST. TRUNK OF INT ILIAC
ANT TRUNK OF INT. ILIAC.
SUPERIOR VF-I. n
OBLITERATED I) I
OBTURATOR
INFERIOR VESICAL
MIDDLE VESICAL
MID BiCMOKRHOTDAJ

INTERNAL II HI
SCIATIC

MIDDLE VESICAL

DEEP EriUASTRIC

Fig. 84.

The arteries of the trunk.

THE HEART AND VASCULAR SYSTEM. 197

Inferior vesical (a. vesicalis inferior), supplies the prostate
gland, base of bladder and vesiculae seminales ;

Middle hemorrhoidal (a. hcemorrhoiddlis media), supplies
part of the rectum ;

Obturator (a. obiuratoria), passes along the side of the
pelvis to the obturator foramen, through which it passes. It
gives off within the pelvis the iliac (ramus ifiacus), vesical
1 ram us vesicalis), and pubic (ramus pttbicus) branch;

Internal pudic (a. pudenda interna), supplies the external
organs of generation. It passes out of the pelvis through the
great sacrosciatic foramen, winds around the ischial spine, and
re-enters the pelvis through the lesser sacrosciatic foramen.

It gives off the following branches in the perineum : —

(a) Inferior hemorrhoidal (a. hcBmorrhoidalis inferior), supplies
the muscles and skin of the anus;

(b) Superficial perineal (a. perinei) , supplies the erector penis
and accelerator urinae muscles and the scrotum;

(c) Transverse perineal, crosses the perineum on the transversus
muscle, which, together with the structures between the bulb and anus,
it supplies;

(d) Bulbourethral, artery of the bulb (a. bulbi urethras), sup-
plies the bulb of the spongy body and Cowper's gland;

(e) Cavernous [a. profunda penis), supplies the corpus caver-
nosum, and is one of the terminal branches:

{f) Dorsal artery of penis, or clitoris (a. dorsalis penis), runs
forward on the dorsum and supplies the glans and prepuce.

In the female the internal pudic artery is of smaller size,
but its course and distribution is quite analogous to its study
in the male subject, i.e., the superficial perineal artery supplies
the labia pudendi ; the artery of the bulb, the vestibule, and the
vaginal erectile tissue, the artery of the corpus cavernosum, the
clitoris; the arteria dorsalis clitoridis, the dorsal surface of the
clitoris, being distributed to the membranous fold in the glans
clitoris, the analogue of the male prepuce.

Sciatic artery supplies the muscles at the back of the pelvis,
coccygeug, pyriformifl and levator ani, and passes out of the
greal sacrosciatic foramen to follow the course of the sciatic
Its branches external to the pelvis are: —

Coccygeal, supplies back part of coccyx;

Inferior gluteal [a. gluteal inferior), to the gluteus maximus
muscle :

< omes nervi iachiadici ('/. lomilaiis ». ixchiadici), runs in the
rabctance of the great sciatic nerve;

Mii-enlar, to the back part of the hip;
Articular, to supply the capsule of the hip-joint.

198 HUMAN ANATOMY.

Uterine (a. uterina), is distributed to body of uterus,, giv-
ing branches to the ureter and bladder ;

Vaginal (a. vaginalis), supplies the mucous membrane of
the vagina, giving branches to the rectum and neck of the blad-
der. It is analogous to the inferior vesical, in the male.

From the posterior trunk

Iliolumbar (a. iliolumbalis) gives off two branches: —

Lumbar {ramus lumbalis), supplies quadratus lumborum
and psoas muscles;

Iliac {ramus iliacus), supplies iliacus, gluteal and abdomi-
nal muscles.

Lateral sacral {a. sacralis lateralis), are two in number —
the superior and inferior, supplying the contents of the sacral
canal ;

Gluteal {a. glutece superior), gives a superficial and deep
branch to supply the gluteus maximus, medius and minimus
muscles.

THE EXTERNAL ILIAC ARTERY (A. ILIACA EXTERNA)

extends from the bifurcation of the common iliac to Poupart's
ligament, under which it passes to become the femoral.

Relations. — It is in relation in front with the peritoneum and
intestines, circumflex iliac vein, spermatic vessels, genitocrural nerve
and the lymphatic vessels and nerves; behind, it rests upon the psoas
muscle, and is in relation with the external iliac vein, which, together
with the vas deferens, is also in relation to it, on its inner side, beneath
Poupart's ligament. On its outer side it is in relation with the psoas
inagnus and iliac fascia.

Its branches are : —

The deep epigastric {a. epigastrica inferior), arises above
Poupart's ligament and ascends obliquely inward between the
transversalis fascia and peritoneum to the rectus muscle, in
which it ascends to anastomose with the termination of the
internal mammary artery. It gives off: —

Cremasteric {a. spermatica externa [male]; a. ligamenti teretis
uteri [female] ) branch, to supply the cremasteric muscle;

Pubic ( ramus pubicus ) , crossing Poupart's ligament to descend
to the inner side of the femoral ring, and

. Muscular, to supply abdominal muscles and the peritoneum.

The deep circumflex iliac {a. circamflexa ilium profunda)
ascends outwardly behind Poupart's ligament to the crest of the
ilium, where it gives off : —

Muscular branches, to supply the abdominal muscles.

ILIOLl MPAR

1MTEKNAI Hue

01 m i mi bi 'i roi

]'•[<:. 86.
The arteries of the lower extremity.

THE HEART AND VASCULAR SYSTEM. 199

THE FEMORAL ARTERY (A. FEMORALIs)

extends- from Pouparfs ligament down the inner side of the
thigh to the opening in the adductor magnus — Hunter's canal
■ lis adductorius | llunteri]), where it becomes the popliteal.
Its course corresponds to a line drawn from a point midway
between the anterior superior spine of the ilium and the sym-
physis pubis to the inner tuberosity of the internal condyle. In
the upper part of its course it is superficial, where it passes
through Scarpa's triangle (trigonum femorale), but in the lower
part it passes backward and becomes very deep. Where it passes
under Pouparfs ligament the femoral vein is to the inner side,
and the anterior crural nerve to the outer side; thus, from
within outward, Y. A. N.

Relations. — It is in relation in front with, the sartorius, the long
saphenous nerve, a branch of the anterior crural nerve, and is covered
liv the fascia lata; behind, it is in relation with the psoas magnus,
adductor longus, adductor magnus and pectineus and the profunda
vein, and about the middle with the femoral vein; at its inner side it
is in relation with the sartorius and adductor longus muscles, and at
its upper part with femoral vein; on the outer side, with the vastus
internus, and at its lower part, the femoral vein.

The branches of the femoral artery are: —

Superficial epigastric (a. epigastrica superficialis) , descends
through the saphenous opening in the fascia lata, and ascends
in abdomen, supplying the skin, inguinal glands and superficial
fascia;

Superficial circumflex iliac (a. circumflexa ilium superfi-
cialis), passes outward to the skin of the groin and over crest
of ilium ;

Superficial external pudic (a. pudenda externa superfi-
cialis), supplies the skin on the lower part of the abdomen;

Deep external pudic (a. pudenda externa profunda), sup-
plies the scrotum in the male, the labia pudendi in the female;

Profunda femoris, arises about two inches below Pouparfs
Hi, and passes beneath the adductor longus, giving off
the following: —

External circumflex («. circumflexa femoris lateralis), gives
off ascending, transverse and descending branches, supplying the
muscles on the front of the thigh as low as the knee;

Internal circumflex (a. circumflexa femoris medialis),
internally, supplying the adductor muscles and the hip
joint;

Thn-c perforating (ua. perforans prima, secunda, tertia),
the adductor magnus and brevis, and supply the flexor

200 HUMAN ANATOMY.

muscles of the thigh, and give off the medullary nutrient artery
(a. nutricia femoris). The- vessel terminates by a fourth per-
forating.

Muscular (rami muscular es), vary in number, and supply
the sartorius and vastus internus;

Anastomotica magna (a. genu supremo), gives off two
branches — superficial, accompanying the long saphenous nerve,
and deep branch, to the inner side of knee, and supplies knee
joint.

THE POPLITEAL ARTERY (A. POPLITEA)

descends! from the opening in the adductor magnus to the lower
border of the popliteus muscle, passing behind the knee joint,
where it divides into the anterior and posterior tibial arteries.
Its branches are : —

Muscular, gives off two principal branches : —

Superior, to flexors of thigh and vastus externu's muscles ;

Inferior, or sural (aa. swales), to heads of gastrocnemius
and plantaris.

Cutaneous, supplies the skin of the calf;

Superior external articular (a. genu superior lateralis),
supplies knee joint and vastus externus ;

Superior internal articular (a. genu superior medialis),
supplies knee joint and vastus) internus;

Azygos articular (a. genu media), supplies the synovial
membrane and ligaments of joints ;

Inferior external articular (a. genu inferior lateralis), sup-
plies knee joint and fibular head;

Inferior internal articular (a. genu inferior medialis), sup-
plies knee joint and head of tibia.

THE ANTERIOR TIBIAL ARTERY (A. TIBIALIS ANTERIOR)

descends from the bifurcation of the popliteal at the lower bor-
der of the popliteus muscle ; passes over the upper border of the
interosseous membrane, between the two heads of the tibialis
posticus,- and descends on the anterior part of the interosseous
membrane and lower part of the tibia to the ankle joint, where
it terminates as the dorsalis pedis.

In the upper third of its course it lies between the tibialis anticus
and extensor longus digitorum, resting upon the interosseous membrane,
in the middle third, between the tibialis anticus and extensor proprius
pollicrs, and at the lower third it becomes more superficial, and lies
between the extensor proprius and extensor longus digitorum tendons.

THE HEART AND VASCULAR SYSTEM. 201

Its branches are : —

Anterior recurrent tibial (a. recurrens tibialis anterior),
ascends to supply the front and sides of the knee joint and
anastomose with the anastomotica magna and popliteal;

Posterior recurrent tibial (a. recurrens tibialis posterior),
is an inconstant artery that is given off from the anterior tibial,
before the latter passes through the interosseous space. It sup-
plies the popliteus muscle, and anastomoses with some of the
articular filaments of the popliteal artery;

Muscular, supplying the muscles and skin of the neighbor-
ing parts;

Internal malleolar (a. malleolaris anterior medialis), arises
two inches above the ankle joint, and supplies it and the struc-
tures on its inner side;

External malleolar (a. malleolaris anterior lateralis), sup-
plies the outer side of the ankle.

The doiisalis pedis artery (a. tlorsalis pedis) extends
from the bend of the ankle, where it is continuous with the
anterior tibial, to the first interosseous space, where it divides
into the dorsalis hallucis and the communicating. Its branches
are: —

Tarsal (a. tarsea lateralis), supplies the tarsal articulations
ami the extensor brevis digitorum muscle;

.Metatarsal (a. arctiata), passes to the outer side of the foot,
and gives off three interosseous branches to supply the adjacent
sides of the toes;

Dorsalis pollicis (a. dorsalis hallucis), passes along the
outer border of the great toe, supplying it;

Communicating (ramus plantaris profundus), descends be-
tween the two heads of the first dorsal interosseous to complete,
with the external plantar, the plantar arch;

Interosseous, branches of the tarsal branch, three in num-
ber.

THE POSTERIOR TIBIAL ARTERY (a. TIBIALIS POSTERIOR)

begins at the lower border of the popliteus muscle and descends
along the posterior and tibial side of the leg to the space between
the- heel and the inner ankle, where it passes beneath the abduc-
tor pollicis and divides into the internal and external plantar
arteries.

Relatione. — In tin- upper |>art of its course it lies deeply, being
covered by the gastrocnemius and aoleus muscle, but in the lower part
it becomes more superficial, being covered only by the skin and the
fascia.

202

HUMAN ANATOMY.

Its branches are : —

Peroneal (a. peroncea), descends the inner border of the
fibula, supplying the muscles and skin of that region and the
back of the ankle ;

Anterior peroneal (ramus perforans), a branch of the pero-
neal, pierces the lower part of the interosseous membrane to
supply the dorsum and outer side of the tarsus; „

Muscular, supplies the posterior muscles;

Nutrient (a. nwtritia fib idee), supplies the tibia, being the
largest nutrient artery in the body;

Communicating (ramus communicans) , passes to the pero-
neal;

Internal calcanean (rami calcanei mediates), supplies the
inner side of the sole and heel.

The internal plantar artery (a. plantaris medialis),
the smaller of the two, passes along the inner side of the foot
between the abductor pollicis and the flexor brevis digitorum to
the inner border of the great toe, anastomosing with its digital
branch.

The external plantar artery (a. plantaris lateralis)
passes across the foot to the base of the fifth metatarsal bone,
where it turns inward and crosses the foot to the first inter-
osseous space, where it anastomoses with the communicating
branch of the dorsalis pedis to form the plantar arch. Its
branches are : —

Posterior perforating (rami perforant.es posteriores) , are
three branches which pass between the heads of the dorsal
interossei muscles;

Digital branches (aa. metatarsece plantares) — these are
four branches which supply the adjacent sides of the three outer
toes, and the outer sides of the second and little toes.

Arch

of
aorta,

TABLE OF THE ARTERIAL SYSTEM.

Aorta.

Right coronary.
Left coronary.

Innominate,

Left common carotid,
Left subclavian.

(Right common f External carotid,
carotid, \ Internal carotid.

Right subclavian.

/ External carotid,
I Internal carotid.

THE HEART AND VASCULAR SYSTEM.

203

r Ilyoid,

Superiot i Superficial descending branch,

thyroid, 1 Superior laryngeal,

I Cricothyroid.

External

carotid,

External

carotid -
continued,

Lingual,

Ilyoid,
Dorsalis linguse,

i Sublingual,
I Ranine.

Facial,

In the
aeckj

On the
face,

Inferior or ascending palatine,
tonsillar, submaxillary, sub-
mental, muscular.

Muscular, inferior labial, inferior
coronary. superior coronary,
lateralis nasi, angular.

Occipital, J

p Muscular.

[ Sternomastoid,

Auricular,

Meningeal,

Arteria princeps cervicis,

Cranial branches.

r Stylomastoid,
Posterior j Auricular,
auricular, 1 Muscular,

I Glandular.

Ascending 1 Pharyngeal, external meningeal,
pharyngeal /•'"»' &

Pi

Temporal,

Transverse facial,
Middle temporal,
Auricular,
Anterior temporal,
Posterior temporal.

Internal
maxillary,

Maxillary
portion,

' Tympanic ( anterior ) ,
Deep auricular,
Middle meningeal,
Small meningeal,
Inferior dental.

i Deep temporal,

Pterygoid J Pterygoid,

portion. 1 Masseteric,

I Buccal.

Spheno-
maxillary
pari ion.

Alveolar,
Infraorbital,
. Tost, or ascending palatine.

j Vidian,
Pterygopalatine,

N'asal or splicnopalatal.

204

HUMAN ANATOMY.

i

o

-a

X

ortion9 } Tympanic -( internal, or deep).

Cavern-
ous
portion,

Arterise receptaculi,
Anterior meningeal.

Ophthalmic,

Orbital
group,

Ocular
group,

Lachrymal,

Supraorbital,

Post, ethmoidal,

Ant. ethmoidal,

Palpebral,

Frontal,

Nasal.

Muscular,
Ant. ciliary,
Short ciliary,
Long ciliary,
Arteria centralis
retinae.

Cerebral
portion,

Verte-
bral,

r Anterior cerebral,
j Middle cerebral,
I Anterior choroid,
L Posterior communicating.

Cervical Branches,

Thyroid
axis,

Lateral spinal,
Muscular. .

Cranial Branches,

, A .

Posterior meningeal,
Anterior spinal,
_ Posterior spinal.

Inferior thyroid,

Superior scapular,

( Transversalis humeri ) ,

Transversalis colli,

Transverse,
Anterior inferior
Basilar, <j cerebellar,

Sup. cerebellar,
Post, cerebral.

' Laryngeal,
Tracheal,
Esophageal,
Ascend, cervical,
Muscular.

/ Muscular,

\ Supraacromial,

/ Superfic. cervical,
\ Post, scapular.

f Comes nervi phrenici (superior phrenic),
j Mediastinal,
Pericardiac,
Internal! sternal,
mam- -s Anterior intercostal,
mary, | Perforating,

| Musculophrenic,
[ Superior epigastric.

Superior
inter-
costal.

• Deep cervical branch (profunda cervicis),

THE HEART AND VASCULAR SYSTEM.

205

Axillary, <

Acromiothoraeic,

Superior thoracic,
Thoracica longa,
Thoracica alaris.

f Dorsalis scapulae,
Subscapular, j Median branch.

Anterior circumflex,
Posterior circumflex.

' Superior prof unda,
Nutrient artery,
Inferior profunda,
Brachial, \ Anastomotica magna,
Muscular,
Radial,
Ulnar.

Radial,

In foramen,

In the wrist,

In the hand,

C Radial recurrent,
i Muscular,

Superficialis volse,

L Anterior carpal

r Posterior carpal,
J Metacarpal,
\ Dorsalis pollicis,

i. Dorsalis indicis.

r Princeps pollicis,
J Radialis indicis,
\ Perforating,
[_ Interosseous.

Ulnar.

In the forearm,

\ In the wrist,

i

I In the hand,

.-Anterior ulnar recurrent,
J Posterior ulnar recurrent,
i Interosseous,

I Muscular.

J Anterior carpal,
\ Posterior carpal.

f Dee]), or communicating branch,
\ Digital.

206

HUMAN ANATOMY.

Thoracic
aorta,

Descending Aorta.

Pericardiac,
Bronchial,
Esophageal,
Posterior mediastinal,
Intercostal.

Abdominal
aorta

Two phrenic.

Celiac axis, ..

Gastric.

f Pyloric.

f Pancreatico-
duodenalis
Hepatic, J Gastro- I superior,

1 1 duodenalis, j Gastro-

! epiploica

[_ dextra.

Cystic.

Splenic

f Pan

, -I Gas
(. Gas

Pancreatic,

troepiploica sinistra,
Gastric (vasa brevia).

Superior
mesenteric,
Suprarenal, ■<
Renal,

Pancreaticoduodenal inferior,
iVasa intestinalis tenuis,
Ileocolic,
Colica dextra,
Colica media.

Spermatic.

Inferior
mesenteric,

Colica sinistra,

Sigmoid,

Superior hemorrhoidal.
Lumbar (four or five branches),
Dorsal branch,
Spinal branch,
Abdominal branches,
Middle sacral,

THE HEART AND VASCULAR SYSTEM.

207

c i

I

z
O

Branches to
ureter, peritoneum etc.

Internal
iliac,

Anterior
trunk.

External
iliac,

Femoral
i continuation i ,

Posterior
trunk,

Superior vesical,

Middle vesical,
Inferior vesical,
Middle hemorrhoidal.

( Ibturator,

Within
pelvis,

Without

pelvis,

Iliac,

Vesical,

Pubic.

r External

and
j internal
t branches.

Internal
pudic,

C Inferior hemorrhoidal,
| Superficial perineal,
J Transverse ])erineal,
1 Bulbourethral,

Cavernous,

Dorsal art'y of the penis.

Sciatic,

In the

Coccygeal,

Inferior gluteal,

Comitans nervi ischiadici,

Muscular,

Articular.

female.

Uterine,
Vaginal.

iliolumbar,
Lateral sacral,
Gluteal.

_, f ( remasteric,

,)"']1. Pubic,
epigastric! MuBCular<

Deep f

circumflex -I

iliac, (

Muscular branches.

Superficial epigastric,
Superficial circumflex iliac,
Superficial external pudic,
Deep external pudic.

Profunda.

External circumflex,
[nternal circumflex,
Three perforating.

Muscular,

\n;i stomol ica magna,
Popliteal i oonl inuation),

208

HUMAN ANATOMY.

Popliteal,

Anterior
tibial,

f Superior,

Muscular,

(_ Interior.

Cutaneous,

Superior external articular,

Superior internal articular,

Azygosi articular,

Inferior external articular,

Inferior internal articular,

Anterior tibial,

Posterior tibial,

> Bifurcation.

Recurrent tibial,
Muscular,
Internal malleolar,
External malleolar.

Dorsalis pedis
( continuation ) ,

Tarsal, 1 Three

Metatarsal, J interosseous.
Dorsalis pollicis or hallucis,
Communicating,
Interosseous.

Posterior
tibial,

Peroneal,
Muscular,
Nutrient,
Communicating,
Internal calcanean,

Anterior peroneal.

Internal plantar, j Bifurcation.
External plantar, J

(fromexteraal 1 Three Posterior perforating,
( plantar) J F°Ur ****

Pulmonary Artery (a. pulmonalis). — The pulmonary
artery carries venous blood from the right ventricle to the lungs.
It 'is about two inches in length, passes upward and backward
to the left side to the under surface of the transverse portion of
the arch of the aorta, where it divides into the right and left
pulmonary arteries. It is attached to the under portion of the
arch by a fibrous cord, the remains of the ductus arteriosus of
fetal life (lig amentum arteriosum). The right pulmonary
artery (ramus dexter a. pulmonalis) is larger and longer than
the left (ramus sinister a. pulmonalis), and passes behind the
ascending aorta and superior vena cava to the root of the right
lung, where it divides into two branches. The left pulmonary
artery passes in front of the descending aorta and left bronchus
to the root of the left lung, where it divides into two branches.

THE HEART AND VASCULAR SYSTEM. 209

THE VENOUS SYSTEM.

The venous system, like the arterial, consists of two dis-
tinct sets, the systemic and pulmonary. It is composed of seven
{ J ) main trunks and their branches : —

Systemic. Pulmonary.

1. Coronary vein; Four pulmonary veins.

2. Superior vena cava;
3. Inferior vena cava.

The systemic veins return the venous blood from the body,
head and extremities to the right auricle.

The portal vein, with its branches and capillaries, is an
appendage to the systemic set, collecting the venous blood from
the organs of digestion, i.e., stomach, intestines and the pan-
creas ;*and also from the spleen, and carrying it to the liver,
where it breaks into capillaries, and finally reaches the inferior
vena cava by means of the hepatic veins.

The pulmonary veins (v. pulmonales) are peculiar in carry-
ing arterial blood from the lungs to the left auricle.

Systemic Veins. — The coronary sinus (sinus coronarius)
returns all the blood from the substance of the heart, except that
returned directly from the walls of the right auricle by the vena
Thehesii | venoe cordis minima). It is a dilatation of the great
cardiac vein, about one inch in length, situated in the posterior
part of the left auriculoventricular groove. It opens into the
right auricle, its orifice being protected by the coronary valves,
and receives the following : —
Great cardiac, or left coronary Right cardiac or small coronary

vein [v. cordis magna); vein {v. cordis parva.) ;

Anterior cardiac (vv. cordis an- Left cardiac vein ( r. posterior ven-

t, , lores) ; triculi simstri I ;

Middle cardiac or posterior (v. Oblique vein of Marshall (v. ob-

cordis media) ; /'7»« «*r" sinistn).

The superior vena cava (v. cava superior) is a short trunk
formed by the union of the right and Left innominate wins. It
receives the vena azygos major (v. azygos), has no valves, and
is smaller in size than the aorta. It ends in the right auricle,
receiving the blood from the whole upper half of the body and
the right Lymphatic and thoracic duets. The left innominate

anonyma sinistra) passes to join the superior cava m front
of the greal arteries of the arch. The inferior thyroid, the
internal mammary and vertebra! veins follow closely the courses
0f the corresponding art. Tie., and terminate in the innominate

Vein.

u

210 HUMAN ANATOMY.

The internal jugular vein (v. jugularis interna) is formed
by the lateral and thq superior petrosal sinuses, descends at the
outer side of the common carotid behind the anterior border of
the sternomastoid muscle, and joins the subclavian vein to form
the innominate. At its junction with the subclavian the left
internal jugular vein receives the thoracic duct and the right
internal jugular vein the right lymphatic duct.

The Sinuses of the Dura Matek (sinus dwrce matris) . —
These are venous channels analogous to veins between the
layers of the dura mater. They are destitute of valves, follow
no vessels, and their inner coat is continuous with the lining
membrane of the veins. They are divided into two sets; those
at the back and upper part of the skull are : —

Superior longitudinal, Lateral sinuses (2),

Inferior longitudinal, Occipital sinus.

Straight sinus,

And those of the base : —

Cavernous (2), Superior petrosal (2),

Circular, Transverse (anterior occipital,

Inferior petrosal (2), Leidy ) .

The superior longitudinal sinus (sinus sagittalis superior)
arises at the foramen cecum, passes backward along the margin
of the falx cerebri to the crucial ridge of the occipital bone,
where it terminates in the torcular Herophili or confluence of
the sinuses.

The inferior longitudinal sinus (sinus sagittalis inferior)
passes in the free margin of the falx cerebri.

The straight sinus (sinus rectus) passes backward from the
junction of the tentorium with the falx cerebri to enter the
confluence of the sinuses.

The lateral sinuses (sinus transversus) pass horizontally
outward from the torcular Herophili, along the temporal bone
to the jugular foramen, where they terminate in the internal
jugular vein.

The occipital sinus (sinus occipitalis), the smallest of all
the sinuses, commences at the margin of the foramen magnum
on either side and passes backward to the torcular Herophili.

The cavernous sinuses (sinus cavernosus) pass from the
sphenoidal fissure along either side of the sella turcica to the
apex of the petrous portion of the temporal bone, where they
join the petrosal sinuses. They are crossed by fibrous bands or
offsets of the dura mater, and inclose the pathetic, motor oculi,

THE HEART AND VASCULAR SYSTEM. gH

abducens and ophthalmic nerves, and the internal carotid artery,
from which they are separated by the lining membrane.

The circular sinus (sinus circularis) is formed by two small
vessels (sinus intercavernous anterior et sinus intercavernous
posterior) passing in front of and behind the pituitary body,
and connecting the cavernous sinuses.

The inferior petrosal sinus (sinus petrosus inferior), on
each side, runs in a groove between the petrous portion of the
temporal bone and the basilar portion of the occipital, connect-
ing the cavernous sinuses with the lateral sinuses.

The superior petrosal sinus (sinus petrosus superior), on
each side, passes along the upper border of the petrous portion
of the temporal bone, connecting the cavernous with the lateral
sinuses* above.

The transverse or basilar (plexus basilaris) is a small,
straight sinus, connecting the inferior petrosal and cavernous
sinuses.

Sphenoparietal sinus (sinus sphenoparietal) runs in a
groove on the under surface of the lesser wing of the sphenoid.
It takes origin from the middle meningeal veins, runs inward.
passes through a fold of dura mater, and usually receives the
anterior temporal veins1 from the diploe.

Cerebral Yeixs (vence cerebri). — The cerebral veins con-
sist of two sets — the superficial, on the surface, and the deep,
within the substance. They include: —

Superficial (vence cerebri externa) —

Superior cerebral veins (vv. cere- Inferior cerebral veins (re. cere-
bri superior es) , bri inferiores).

Deep — ■

Ventricular veins, or venae Galeni Veni corporis striati and choroid

i //•. (inh iii ; it. cert bri interna} | , vein (v. choroidca).

The cerebellar veins consist of the superior superficial cere-
bellar veins (vv. cerebelli superiores) , and the inferior super-
ficial cerebellar veins (vv. cerebelli inferiores) ; blood is brought
from the interior to these superficial veins through the deep
cerebellar veins.

Diploic and Meningeal Yeixs. — The diploic veins (vence
diploica), five in number, — frontal (v. diploica frontalis), an-
terior temporal (v. diploica temporalis anterior), posterior tem-
poral (v. diploica temporalis posterior), occipital (v. diploica
occipitalis superior) -communicate with the sinuses of the brain

and with the vein- of the dura mater, the scalp and orbit.

212 HUMAN ANATOMY.

The meningeal veins (vv. meningeal) follow the course
of the corresjDonding arteries, two accompanying each vessel
through its course, and open into the sinuses of the dura mater.

The great meningeal veins terminate either in the cavern-
ous sinuses or by emptying into the internal maxillary vein.

The ophthalmic superior vein (v. ophthalmica superior)
commences at the internal canthus of the eye in an anastomosis
with the facial, passes backward along the inner part of the orbit,
through the sphenoidal fissure, to empty into the cavernous
sinuses.

The inferior ophthalmic vein (v. ophtlialmica inferior)
arises from the veins of the eyelids and the lachrymal sac. It
runs backward along the floor of the orbit and joins the superior
to form a common trunk, or else it enters the cavernous sinus
by a single opening'.

The external jugular vein (v. jugularis externa), smaller
than the internal jugular, is formed by the union of the pos-
terior auricular with the temporomaxillary veins; or it may be
formed by union with the facial. It descends beneath the
platysma muscle from the angle of the jaw to the middle of the
clavicle, where it terminates by emptying into the subclavian.
It receives the following veins : —

Anterior jugular, Suprascapular,

Posterior jugular, Transverse cervical.

The anterior facial vein (v. facialis anterior) commences
as the angular at the internal canthus of the eye, where it anas-
tomoses with the ophthalmic vein, and receives the frontal vein.
About the angle of the jaw it usually ends in the internal
jugular, but sometimes empties into the external jugular or
unites with the temporomaxillary (v. facialis posterior), to
form the common facial vein.

The common facial vein (v. facialis communis), formed by
the union of anterior facial and the anterior division of the
temporomaxillary vein, runs backward beneath the sternomas-
toid muscle, crosses the external carotid artery, and empties into
the internal jugular. It receives: —

Supraorbital {v. supmorbitalis) Labial,

and superior palpebral, Submental,

Nasal veins, Submaxillary,

Inferior palpebral, Palatine.
Buccal and masseteric,

The temporal vein, which is known, as far as the zygoma,
as the superficial temporal vein {vv. temporaries superficiales) , is

THE HEART AND VASCULAR SYSTEM. 213

formed by the anterior temporal, which anastomoses with the
frontal, and the posterior temporal, which anastomoses with the
occipital. It penetrates the parotid gland and forms the tem-
poromaxillary vein by uniting with the internal maxillary. It
receives : —

Articular veins, Transverse facial,

Anterior auricular, Parotid.

Middle temporal [v. temporalis
media ) ,

The internal maxillary vein follows the course of the
corresponding artery, and receives veins corresponding to the
branches of that vesssl. Some of these branches form the
pterygoid plexus. It passes backward and unites with the tem-
poral vein to form the temporomaxillary.

The temporomaxillary vein (v. facialis posterior), formed
by the junction of the internal maxillary in part or whole with
the temporal, passes through the parotid gland and receives the
posterior auricular, to form the external jugular vein.

The occipital vein (v. occipitalis) follows the course of the
artery, and terminates, usually, in the internal jugular; occa-
sionally, in the external jugular. The mastoid vein, passing
through a foramen in the mastoid portion, connects it with the
lateral sinus.

Veixs of the Tongue and Throat. — The veins of the
tongue empty into the internal jugular. The lingual veins (vv.
linguales) begin near the tip of the tongue under the name of
the ranine; they commence on the dorsum, sides and under sur-
face, and pass backward, receiving the dorsal lingual vein, and
also the sublingual vein, as well as two small veins (vena'
comites), and terminate in the internal jugular.

The pharyngeal (vv. pharyngece) , commencing in the
pharyngeal plexus (plexus pharyngeals), receives branches from
the brain, and terminates about on a level with the hyoid bone
in the internal jugular.

The superior thyroid (v. thyreoidea superioris) conveys the
Mood from the larynx, trachea and thyroid gland to the interna]
jugular.

Veins of the Upper Extremity. — Superficial and deep.

The subclavian vein (v. subclavia), the continuation of the
axillary, unites with the interna] jugular to form the innomi-
nate. In its passage over the first rib it is separated from the
artery by the Bcalenue anticufi muscle.

214 HUMAN ANATOMY.

Deep Set. — The deep veins accompany the corresponding
arteries and form the venae comites, one on either side, except
the axillary, which has a single vein. The valves are more
numerous in the deep set. About the middle of the arm one
of the brachial veins receives the basilic vein, one of the larger
veins of the superficial set. The two brachial veins unite with
the basilic to form the axillary vein, which in turn becomes the
subclavian vein, receiving in its course beneath the clavicle the
cephalic vein, a branch of the superficial set.

Superficial Set. — The anterior ulnar vein (v. ulnaris ante-
rior) commences on the inner surface of the hand and wrist,
and terminates by uniting with the posterior ulnar (v. ulnaris
posterior) or the median vein. The posterior ulnar vein com-
mences on the inner back portion of the hand, anastomosing
with the radial cutaneous vein, and ascends to the bend of the
elbow, where it becomes the basilic vein;

The basilic vein (v. basilica), from its formation at the
bend of the elbow, ascends the inner side of the biceps, pierces
the fascia, to join the brachial vein.

The radial (v. radialis) commences on the radial, dorsal
aspect of the hand, and at the bend of the elbow unites with
the median cephalic, to become the cephalic.

The cephalic vein (v. cepnalica) ascends along the outer
border of the biceps, and above in the groove between the deltoid
and pectoralis major, and passes beneath the clavicle, to end in
the axillary.

The median vein (v. mediana cubiti) receives the blood
from the palmar surface of the hand and the front of the fore-
arm, and usually divides into two branches — the median ce-
phalic, passing outward to join the cephalic, and the median
basilic, passing inward to join the basilic. The median basilic
vein, the larger, is the one usually selected for phlebotomy.

Veins of the Trunk. — The vena azygos major (v. azygos)
commences in the abdomen, opposite the first or second lumbar
vertebra, as a continuation upward of the right ascending lum-
bar vein. It communicates with the right renal and the inferior
vena cava. Through the lumbar veins it establishes communi-
cation with the right common iliac vein. It passes through the
aortic opening of the diaphragm, or through an aperture in the
right crus, ascends on the dorsal vertebras, arches over the root
of the right lung, and empties into the superior vena cava. It
is in relation on its left side with the aorta, thoracic duct and
esophagus. It receives

THE HEART AND VASCULAR SYSTEM/' 215

Vena azygos minor ( v. hernia- Lower 8 or 9 intercostal veins,

zygos), Right superior intercostal vein.

Left upper azygos vein ( vena liemi- Right subcostal vein,

azygos accessoria), Esophageal (vv. nsophagea) ,

Lower end of left superior inter- Right bronchial,
costal vein,

The hemiazygos veins are two in number : —

The vena azygos minor (v. hemiazygos) arises on the left
side, similarly to the azygos major, and passes through the left
eras of the diaphragm and about the eighth dorsal vertebra
crosses beneath the aorta to join the vena azygos major;

Left upper azygos vein (vena hemiazygos accessoria) com-
municates with the upper left intercostal vein, and terminates
either in the vena azygos minor or the azygos major.

The ascending or inferior cava (v. cava inferior), formed
by the junction of the common iliac veins, at the sides of the
fourth lumbar vertebra, ascends on the right of the aorta,
grooves the posterior border of the liver, and passes through the
quadrate foramen in the central tendon of the diaphragm, and
ends in the right auricle, where it is provided with the Eusta1
chian .valve (valvula v. cavce inferioris [Eastachii]) . It
receives

Middle sacral, Renal veins (vv. renales) — the left,

Lumbar (vv. lumbales), the longer, crosses in front of

Spermatic (vv. spermatica') , from the aorta,

spermatic plexus (plexus pam- Suprarenal (vv. suprarenales) ,

piriformis), Phrenic (vv. phrenica') ,

Ovarian (vv. ovmica) , from Hepatic (2 or 3) (vv. hepaticrr) .

ovarian plexus (plexus arteries

ovariece) .

The portal vein (vena porta?), about three inches in length,
is formed by the inferior and superior mesenteric, the gastric,
splenic and pancreatic veins. It ascends in the right border of
the lesser omentum to the transverse fissure of the liver, where
it divides into the right and left. Its blood is distributed
through the liver, mixing with the arterial blood from the
hepatic artery, to be returned to the inferior cava by the hepatic
veins. It receives

The superior mesenteric (v. mesen- Cystic (v. cystica),

terioa superior), Inferior mesentery (v. mesenterica

Splenic (v. Uenalis), inferior),

Ctoronary (v. coronaria ventric- iliglit gastroepiploic.

uli) .

216 HUMAN ANATOMY.

The portal vein and its branches are destitute of valves.

Veins op the Vertebral Column. — 1. The dorsi-spinal
veins (plexus venosi vertebrates externi) commence in an intri-
cate network surrounding the vertebral arches and their proc-
esses. They communicate with the intercostal, vertebral, intra-
spinal plexus, lumbar, sacral and the superficial veins of the
back.

2. The intraspinal or meningorachidian veins (plexus ve-
nosi vertebrates interni) form an intricate plexus between the
vertebras and dura mater within the spinal canal. They coiit
sist of four longitudinal veins — two in front and two behind.
The anterior longitudinal spinal veins (sinus vertebrates long-
tudinales), two in number, extend along the sides of the verte-
bral bodies and opposite the bodies communicate by transverse
trunks, which, in their passage beneath the vertebral ligament,
receive the diploic veins, or venae basis vertebras (v. basiverte-
bralis), from the interior of the body. The posterior longitu-
dinal veins, also two in number, smaller than the anterior,
extend down the vertebral arches and are connected by trans-
verse branches opposite the latter.

They receive the veins from the spinal cord and its mem-
branes.

3. The venae basis vertebrae (v. basivertebral^) return the
blood from the bodies of the vertebrae into the anterior intra-
spinal plexuses.

The venae medulli spinalis (vv. spindles) are the essential
veins of the cord, situated between the arachnoid and pia mater.

Common Iliac Veins (v. iliaca communis) .

Formed by the internal and external iliac veins uniting
opposite the sacroiliac articulation, pass beneath the right com-
mon iliac artery to a point a little to the left of the body of
the last lumbar vertebra, where they unite to form the inferior
vena cava. The right is shorter and more vertical in its course,
and both are without valves.

The internal iliac or hypogastric vein (v. iliaca in-
terna or v. hi/pogastrica) corresponds to the distribution of the
corresponding artery.

It receives the following venae comites: —

Gluteal (vv. glutece), Lateral sacral (vv. sacrales lat-

Sciatic, erales) and

Obturator (v. obturatoriw) , Middle sacral;

Internal pudic (vv. pudendce in-
ternee),

THE HEART AND VASCULAR SYSTEM. 217

and the following plexuses: —

EZS2SS? f»—« EST- }.■»*-*

The lateral and middle sacral form a small plexus — the
plexus saeralis.

The veins of the rectum, bladder, and generative organs
anastomose freely and form three plexuses : —

1. Hemorrhoidal plexus (plexus hamorrhoidalis) encircles
the lower part of the rectum, communicates with the sacral and
prostatic plexuses, and veins from it join the inferior mesen-
teric, internal iliac and. pudic veins.

2. Vesica prostatic plexus surrounds the membranous por-
tion of the urethra, neck of bladder, prostate body and seminal
vesicles. It communicates behind with the hemorrhoidal.

3. Uterovaginal plexuses (plexus utero vaginalis) . — These
correspond in the female with the prostatic, and communicate
with the vesical and hemorrhoidal plexuses, the ovarian, pudic,
and. through the uterine veins join the internal iliac veins.

During pregnancy these veins or plexuses become greatly
distended and enlarged, forming the uterine sinuses, but retain
a straight course.

The pudic vein follows the same course as the artery, com-
municates with the prostatic and hemorrhoidal plexuses, and
terminates in the internal iliac vein.

In the female it originates from the clitoris and perineum,
and communicates with the vaginal plexus.

The dorsal vein of the penis (v. dorsdlis penis) returns the
blood from the body of that organ. It commences as two venae
comites of the dorsal artery, which unite on the dorsal surface
of the root of the penis, perforates the triangular ligament, and
again divides to terminate in the prostatic plexus.

The veins of the corpus cavemosum emerge at the lower
groove, and turn round their outer side to join the dorsal vein.

The dorsal vein of the clitoris has a corresponding origin
and course, and empties into the vaginal plexus.

The EXTERNAL iliac vein (v. iliaca externa,), the con-
tinuation of the femoral, lies internal to the artery beneath
Pouparfs Ligament, and joins the interna] iliac opposite the
sacroiliac symphysis, to form the common iliac vein, it runs
along the brim of the pelvis. It receives at its commencement
the \ <n;t- comites of the epigastric artery and the circumflex

iliac.

218 HUMAN ANATOMY.

Lower Extremity. — The deep veins of the lower extrem-
ity pursue the exact course of the corresponding arteries, anas-
tomosing across the vessels they accompany, except the femoral,
which has but one vein.

The popliteal vein (v. poplitea), formed by the junction of
the anterior and posterior tibial veins, ascends) to the lower mar-
gin of Hunter's canal, where it becomes the femoral. It receives
the articular veins, sural veins and the external saphenous. At
its commencement it lies internal and superficial, at the middle
of the space directly behind, and, in the upper part of its course,
external to the artery.

The femoral vein (v. femoralis) , at first behind the artery,
inclines to the inner side as it ascends^ and at Poupart's liga-
ment becomes the external iliac. It receives the profunda
femoris, the internal saphenous vein, and numerous muscular
veins.

The superficial veins of the lower extremity consist of two
principal trunks: the external short saphenous (v. saphena
parva) commences on the dorsum of the foot, passes behind the
outer malleolus, ascends the leg, and pierces the deep fascia in
the popliteal space, to terminate in the popliteal vein. The
long saphenous vein (v. saphena magna), the larger, arises
from the dorsum and inner side of the foot, ascends the front
and inner side of the leg and thigh, and passes through the
saphenous opening to join the femoral vein.

The; Pulmonary Veins (v. pulmonales) . — The pulmonary
veins are four short, venous trunks, two from the base of each
lung passing to the left auricle, returning arterial blood.

They differ from other veins in the following respects : —

1. They are without valves;

2. They carry arterial blood;

3. They accompany the arteries singly;

4. They are a little larger than their arteries.

The right are longer than the left, ano\ pass from the root
of the lung, on a lower level than the artery, behind the aorta,
superior cava and right auricle, to enter the left auricle.

The Lymphatic System.

The lymphatic system includes the lymphatic vessels,
glands and the lacteals, and forms an important accessory to
the blood-vascular system, collecting the transuded, unappro-

THE HEART AND VASCULAR SYSTEM. 219

prfated fluids of the body, and the nutritive material derived
from the food, and conveying it into the venous system.
It- consists of two main trunks : —

(a) Thoracic duct {ductus thora- (b) Right lymphatic duct (ductus
us) • lymphaticus dexter) ;

and five smaller trunks: —

1. Jugular lymphatic trunk;

2. Subclavian lymphatic trunk:

3. Bronchomediastinal lymphatic trunk;

4. Lumbar lymphatic trunk;

5. Intestinal lymphatic trunk.

Lymphatics have been found in nearly every organ and
texture in the body except the brain, the spinal cord, cartilage,
tendon, eyeball, placenta, umbilical cord, membranes of the
ovum, hair, cutis and the labyrinth of the ear. They appear
to originate as a fine capillary network interwoven among the
blood vessels and proper elements of the tissues, or, more
minutely, in the lymph, perivascular, and perineural spaces. In
the villi they commence as closed, club-like tubes.

The lymphatic capillaries are somewhat larger than the
vascular capillaries and destitute of valves. Their main trunks
pass through lymphatic glands lying in their course; before
doing which, however, they divide into afferent vessels, which.
on emerging, nnite into a smaller number of large vessels, the
efferent.

In structure, they are composed of three coats — the exter-
nal fibroareolar, middle muscular, and internal or endothelial
and elastic.

The lymphatic glands (lymphoglandula) are generally sit-
uated in the course of the blood vessels, lymphatic vessels, or
Lacteal vessels, being accumulated together in certain localities,
as the neck, abdomen, axilla, etc.

The lymphatic glands and vessels are named from the
regions they occupy or the vessels they accompany, and consist
usually of a superficial and deep set. Thus, we have cervical,
axillary, mediastinal, lumbar, inguinal, etc., and the lymphatic
vessels corresponding.

The lacteals, or clujliferous vessels, are the lymphatic ves-
sels of the small intestine, and differ only from the others in
carrying chyle during digestion from the intestines to the
thoracic duct.

The thorai i< di ct (ductus thoradous) is formed by the
junction of the two Lumbar Lymphatic trunks with the intestinal

220 HUMAN ANATOMY.

lymphatic trunk, in front of the second lumbar vertrebra,
between the aorta and inferior vena cava, as the receptaculum
chyli, or cistern of Pecquet (cistema chyli). This receptacle
is about one to two inches long and a quarter of an inch wide.
From its. origin the thoracic duct ascends through the abdomen,
passes through the aortic orifice in the diaphragm, and ascends
behind the esophagus between the aorta and azygos vein to the
fourth dorsal vertebra, where it passes to the left beneath the
aorta, and ascends between the esophagus and the left sub-
clavian artery to the last cervical vertebra, where it arches for-
ward, outward and downward to enter the junction of the
subclavian and the left internal jugular vein at its posterior
aspect. Its orifice is protected by a pair of- valves. It receives
all the lymphatic vessels below the diaphragm, those of the left
side of the head, neck and left upper extremity.

The eight lymphatic duct (ductus lymphaticus dexter)
is about half an inch long and one-twelfth inch wide. It empties
in a corresponding manner on the right side to the thoracic
duct. It receives all the lymphatics of the right side of the
thorax, neck, head and right upper extremity.

Lymphatics op the Head and Neck. — The substance of
the brain is probably destitute of lymphatics, but they are very
numerous in the pia mater and choroid plexuses of the lateral
ventricles, and pursue the same course as the principal veins, to
emerge at the base through the various foramina, to terminate
in the deep cervical glands. The occipital lymphatic vessels
terminate in the posterior auricular, or retroauricular or mas-
toid glands (lympho glandules auriculares posteriores) , and occip-
ital or suboccipital glands (lympho glanduke occipital es) . The
temporal lymphatic vessels terminate in the anterior or auric-
ular glands. The lymphatics of the face are superficial and
deep. The superficial lymphatics are numerous, and terminate
in the submaxillary glands, six or more in number; the deep
lymphatics accompany the branches of the internal maxillary
artery, and terminate in the deep cervical and deep parotid
glands about the ramus of the jaw.

Lymphatics of the Upper Extremity. — Lymphatics of
the upper extremity are composed of two sets, the superficial
and deep. The superficial lymphatic glands are few in num-
ber, one or two only being situated at the internal condyle of
the humerus. The deep lymphatic glands lie along the course
of the vessels, and communicate with the axillary glands. All
of these glands unite in the deep axillary glands (lympho-
glandulw axillares), about eight to ten in number, which com-

THE HEART AND VASCULAB SYSTEM. -j-j]

municate with the deep cervical glands, and through them
empty into the subclavian lymphatic trunk, to end finally in
the thoracic or" right lymphatic duct. The superficial and deep
vessels of the thorax, the former in the skin, the latter from
the mammary glands, pectoral and other muscles, for the most
part, pass to the axilla, a few only terminating in the glands
below the clavicle.

The Cavity of the Thorax.- — The intercostal lymphatic
vessels, derived from the side of the abdomen and thorax,
pleura?, diaphragm, spinal canal, muscles of the back, etc., fol-
low the course of the veins, traverse fifteen to twenty intercostal
glands (tymphoglandulw intercostales) near the heads of the
ribs, and terminate in the thoracic duct. The posterior medias-
tinal glands {lymphoglandvlm mediastinales posteriores) are
between the intercostal glands, and communicate with them,
receiving vessels from the pericardium, esophagus and
diaphragm. Some of the efi'erent vessels end in the bronchial
glands, others in the thoracic duct. The anterior mediastinal
lymphatic vessels (lymplioglandulm mediastinales anteriores)
are derived from the anterior wall of the abdomen and thorax,
the diaphragm, pericardium, upper surface of the liver, heart
and thymus gland. They traverse about eighteen to twenty
anterior mediastinal glands, situated in the course of the inter-
nal mammary vein, pericardium, and great vessels of the heart,
and terminate in thoracic and right lymphatic ducts. The
pulmonary lymphatic vessels consist of a superficial and deep
set, traversing in the last part of their course the pulmonary
glands. The bronchial glands are twenty or more glands at the
bifurcation of the trachea and root of the lungs, and receive the
lymphatic vessels of the lungs and bronchi. They become pig-
mented, and are often the seat of disease. Their efferent vessels
terminate on the right side in the right lymphatic duct, either
directly or by forming the bronchomediastinal trunk, and on
the left side in the thoracic duct.

Lowes Extremity and Pelvis. — The superficial lym-
phatic vessels from the back of the foot follow the course of
the long saphenous vein, passing to the superficial inguinal
glands {lymplio'.itnmlnbi' in/j/dnales supcrficiales) ; and (hose
from the sole of the* foot follow the short saphenous vein, join-
ing the deep set in the popliteal space. The deep lymphatic
vessels follow the; deep veins, traverse two to four popliteal
glands {lymphoglandutcB />ni<lile<r) . and join flic dec]) inguinal
glands (lymphoglandulce inguinales profunda*!). The deep lym-
phatic glanda in the pelvis consist of three sets: the external

222 HUMAN ANATOMY.

iliac, around the external iliac vessels; the internal iliac, around
the internal iliac vessels ; and the sacral glands, on the anterior
surface, and in the mesorectal folds.

Lymphatics of the Abdomen. — The lymphatic vessels of
the external and internal iliac glands enter the lumbar glands,
twenty-five or more in number, situated upon the vertebrae, the
origin of the diaphragm, the psoas and quadratus lumborum
muscles and the great blood vessels. They receive vessels from
the kidneys, ureters, loins, suprarenal bodies, ovaries and testi-
cles, and form lumbar lymphatic trunks, which ascend to join
the thoracic duct or receptaculum chyli. The lymphatic vessels
of the stomach follow the general course of the blood vessels,
They consist of three groups : the first, along the lesser curva-
ture, passing to the glands along the pylorus ; the second, at the
great end of the stomach, passing to the splenic lymphatic
glands ; and the third, at the greater curvature, passing to one
of the principal lacteal vessels. The lymphatics of the small
intestine are called also lacteals. They pass between the layers
of the mesentery and traverse a large number of mesenteric
glands, arranged irregularly into three rows. The lymphatic
vessels of the large intestine traverse the mesocolic glands, about
thirty in number, and pass into the superior mesenteric glands.
The vessels from the spleen and pancreas follow the course of
the splenic vein, traverse a number of the glands, to end in the
celiac glands. The lymphatics of the liver consist of superficial
and deep,' and are very extensive, both on the upper and lower
surfaces. They terminate in the right lymphatic duct, the
glands of the gastrohepatic omentum, the anterior mediastinal
glands, the esophageal glands, the glands of the lesser curvature
and of the thoracic duct. The deep lymphatics follow the
course of the portal vein and hepatic artery and duct, and,
emerging, join, one of the lacteal vessels before it enters into
the thoracic duct. The celiac glands, fifteen or twenty in num-
ber, are situated behind the pancreas and duodenum, the aorta,
portal vein, celiac and superior mesenteric vessels. Their effer-
ent vessels form the intestinal lymphatic trunk and empty into
receptaculum chyli.

THE ALIMENTARY APPARATUS.

The alimentary apparatus consists of the alimentary canal
and of certain accessory organs.

The former is a musculo-membranous canal about thirty feet
in length, extending from the mouth to the anus, and comprises :
first, the organs of deglutition, consisting of the mouth, pharynx,
and oesophagus; and, second, the organs of digestion, consisting
of the stomach and small and large intestines. 'It is lined
throughout by mucous membrane. The accessory organs com-
prise the teeth, salivary glands, liver, and pancreas.

Alimentary
canal,

Alimentary Apparatus.

-{

Mouth,
' Organs of deglutition, -j Pharynx,

(Esophagus.

_ Organs of digestion,

Stomach,

Duodenum,
Small intestine, -j Jejunum,

Ileum.

' Teeth,

tine, <
tine, -I

Caecum,
__ Large intestine, ■{ Colon,
Rectum.

Accessory
organs,

Salivary glands,

Liver,
Pancreas.

f Pa

\ Su
( Su

Parotid,

bmaxillary,
Sublingual.

The mouth (cavum oris) is an oval cavity in which mas-
tication takes place preparatory to deglutition. It is placed at
the entrance of the alimentary canal, is bounded laterally by
the alveolar processes of the upper and lower jaws and cheeks;
above by the upper teeth and hard palate; below by the tongue,
the lower j;iw, the mucous membrane between, and the lower
teeth ; in front by the lips; and behind by fauces and soft palate.
It terminates posteriorly at the anterior pillars of the fauces,
through the fauces into the pharynx.

(223)

224 HUMAN ANATOMY.

It is invested throughout (except on the teeth) with highly
vascular mucous membrane covered with stratified squamous
epithelium containing conical papillae.

It presents for examination the following parts: —

The Teeth (dentes). — The teeth are firmly implanted
within the alveoli of the jaws (alveoli dentales) and surrounded
by the gums.

The gums (gingiva) are composed of dense fibrous tissue,
covered by smooth, vascular, mucous membrane of slight sen-
sibility. This fibrous tissue is continuous with the periosteum
of the jaws, and forms about the neck of the teeth a constricted
ring — the dental ligament.

There are four kinds of teeth — incisors, canines or cuspids,
premolars or bicuspids, and molars. Man is provided with two
sets of teeth, the temporary, deciduous, or milk teeth, which
appear in childhood, and the permanent, which appear after
the shedding of the milk teeth, and last until old age.

The temporary or deciduous teeth (dentes decidui) are
twenty in number, ten in each jaw; or five in each side of each
jaw:—

Two incisors,, one canine, and two molars.

The permanent teeth (dentes permanentes) are thirty-two
in number, sixteen in each jaw, or eight in each side of each
jaw (arcus dentalis superior or areas dentalis inferior) :—

Two incisors, one canine, two bicuspids, three molars.

Each tooth consists of three parts : —

Crown, or body (corona dentis), the enameled portion
above the gum; neck (collum dentis), the constricted portion
between the crown and root; root, or fang (radix dentis),
within the alveolus, and covered with cement.

Characteristics. — Incisors (dentes incisivi), or cutting, are
so-called from their wedge-shaped, chisel-like crown, being
adapted for biting or cutting the food. The fang is long, single,
conical and compressed at the sides.

Cuspids, or canines (dentes canini), have been so named
from their conspicuous character in the canine or dog tribe.

The crown is large, conical, convex in front, and beveled
behind. The fang is single, longest and thickest of all the
teeth.

Bicuspids, or premolars (dentes premolares). The crown
has a pair of projecting tubercles or cusps. Fang is conical,
single, but deeply grooved, indicating a disposition to bifurcate.

Molars (dentes molares), commonly known as grinders or
'jaw teeth. Crown, broad, quadrilateral, with four cusps in

THE ALIMENTARY APPARATUS. 225

upper, five in lower molars. Lower molars have usually a pair
of fangs placed laterally; the upper, three fangs, two external
and one internal.

The last or third molar has but one fang (with a tendency
to divide into the same number of roots as the other molars),
and is known as the dens sapiential, or "wisdom tooth" {dens
serotini), from its late appearance.

Structure. — On section a tooth consists of two portions, the
pulp cavity (vavum dentis) and the solid portion surrounding it.

The solid portion consists of three structures, dentine or
ivory, which forms the principal mass of the tooth; enamel,
which covers the crown, and cement, which covers the surface
of the fang.

Dentine or ivory {substantia? eburnea), resembles bone, but
differs from it in composition and structure, consisting of
twenty-eight parts animal and seventy-two parts mineral mat-
ter, and being made up of minute tubuli held together by the
intertubular substance.

The dental tubuli {canaliculi dental es) are minute cylin-
drical canals /4soo °f an inch m diameter. They pass in a
spiral direction from the pulp cavity to the periphery.

Enamel {substantia adamaniina), the hardest and densest
of all organized bodies, contains but 3.5 per cent, animal matter,
and is composed of minute hexagonal rods {prismata adaman-
iina) %-,oo of an inch in diameter, placed at right angles to
the surface of the dentine. The external surface of unworn
enamel can be separated as a thin, homogeneous membrane,
Nasmyth's membrane {cuticula dentis).

Cement, or crusta petrosa {substantia ossea), is a thin
layer of true bone with canaliculi and lacunas, disposed on the
surface of the fang.

The pulp cavity {cavum dentis) is a cavity within the base
of the crown, continuous with a canal in the center of the fang,
and open at the apex of the fang {canal radicis dentis) for the
entrance of vessels and nerves. It is filled with dental pulp
{put pa dentis).

Den I a / pulp consists of two kinds of cells, the fusiform and
the columnar, or odontoblasts of Waldeyer, held together by
loose connective tissue. It is soft, vascular and highly sensi-
tive. The nerves are both medullated and non-medullated, and
form a rich plexus beneath the odontoblastic layer. The ter-
minal fibrils probably unite with these cells, but the exact dis-
tribution is still unsettled.

15

226

HUMAN ANATOMY.

Development — Temporary. — They are formed very early,
seven to eleven weeks, in the primitive dental groove by an
involution of the epithelium of the oral cavity covering the
maxillary arches into the blastema or corium and connective
tissue below, the former giving the enamel, the latter the cement
and dentine.

The enamel comes from the enamel germ, a mass of epi-
thelial cells, descending into the dental groove until it meets
the dentine papilla (papilla dentis), a vascular growth extend-
ing upward from the connective tissue, upon which it forms a

C.In.
6-8

Fig. 86.

Temporary teeth.

cap. A vascular membrane inclosing the enamel germ then
extends itself — as the dental sac — upon the united papilla and
enamel germ and cuts the latter off from its earlier epithelial
structure. The cells become differentiated and finally calcify.

The dentine is formed by the development of odontoblasts
in the periphery of the papilla in a similar manner to the
development of osteoblasts in bone.

The cement is developed from the wall of the dental sac
by the intramembranous process of ossification.

Permanent.- — The successional permanent teeth, or those
replacing the temporary, are developed in a different manner
from the superadded, or three molars in each side of each jaw.

The former are developed similarly to the temporary teeth,
but in a secondary dental groove, from which, after their for-
mation, they recede behind the germs of the temporary teeth,

THE ALIMENTARY APPARATUS.

227

inclosed in sacs. The molars, or superadded teeth, however, are
formed by extensions backward of a portion of the enamel germ
of the tooth immediately in front.

Eruption, or "cutting of the teeth," takes place by the
growth of the fang, the gums being absorbed by the pressure
of the advancing crown. The development of the fangs of the
permanent causes the ahsorption of the fangs of the temporary
teeth through the agency of the odontoclasts*, multinucleated
cells corresponding to the osteoclasts of bone.

16-20

Fig. ST.
Permanent teeth.

The eruption of the temporary teeth takes place in months
in the order shown in Fig. 86, the lower preceding by a short
time the upper (according to Dr. C. X. Pierce, in "American
m of Dentistry"). The order of the eruptions is: first
the lower central incisors, the upper central incisors, lateral
incisors, upper and lower, first molars, followed by the canines
or cuspids, and ending with the second molars.

The eruption of permanent teeth takes place in years as in
Fig. 87, the order of the eruptions being, firs! the "flrsl or sixth
pear molar/' followed by Hie firs! central incisors, four lateral
incisors, four first bicuspids, four second bicuspids, the first
canines or cuspids, the four second molars, and ending with the
four third molars or "wisdom teeth.'''

228 HUMAN ANATOMY.

About the sixth year the jaws contain the temporary teeth
fully erupted, and the crowns of all the permanent teeth except
the four wisdom teeth, in all forty-eight.

It should be noted that the first permanent or "sixth-year"
molar is erupted before any of the permanent teeth, and that
the second bicuspid takes the place of the second temporary •
molar.

Vessels and Nerves of the Teeth. — The arteries of the upper
teeth are derived from the anterior dental branches of infra-
orbital and posterior or alveolar dental branches of the internal
maxillary; of the lower teeth, from the inferior dental branch
of the internal maxillary.

The nerves are distributed to the upper teeth from the
anterior and posterior dental branches of the superior maxillary
(second division of fifth cranial nerve), and to the lower teeth
from the inferior maxillary (third division of fifth cranial
nerve).

Soft palate (palatum molle) is a movable fold of mucous
membrane suspended from the posterior border of the hard
palate, and' inclosing an aponeurosis, vessels, nerves, glands and
the following muscles on each side ; tensor palati, levator palati,
palatoglossus, palatopharyngeus and azygos uvulse, the latter
uniting with its fellow to form the uvula (uvula palatina).

Hard palate (palatum durum) is formed by the palatal
process of the superior maxillary and the palate bone, and cov-
ered by a thick, dense structure composed of mucous membrane
and periosteum combined. It forms the roof of the mouth, and
presents a median raphe (raphe palati) and corrugated surface
(plicce palatina? transversa?) .

Anterior pillar of the fauces (arcus glossopalatinus) is a
fold of mucous membrane arching downward and forward from
the base of the uvula to the base of the tongue, and inclosing
the palatoglossus muscles.

Posterior pillar of the fauces (arcus pliaryngopalatinus)
is a similar fold arching downward and backward from the base
of the uvula to the sides of the pharynx, and inclosing the
palatopharyngei muscles.

The tonsils (tonsilla palatina), or amygdalae, are small,
almond-shaped, glandular bodies situated on each side of the
fauces between the anterior and posterior pillars. They rest
upon the superior constrictor of the pharynx, which separates
them from the ascending pharyngeal and internal carotid ar-
teries. They are composed of numerous follicles (fossulm ton-
sillares) (lined by closed capsules containing adenoid tissue),

THE ALIMENTARY APPARATUS. 229

which contain a thick, grayish secretion and open on the surface
of the gland by a dozen or more orifices.

The arteries to the tonsil are from the tonsillar and as-
cending palatine of the facial, dorsalis linguae from, the lin-
gual, ascending pharyngeal from external carotid, branch from
small meningeal, and descending palatine branch of internal
maxillary.

The nerves are from glossopharyngeal and Meckel's gan-
glion.

The Salivary (i lands. — The salivary glands communi-
cating with the month are three: the parotid, submaxillary
and sublingual.

The parotid gland (glandules parotis), so called from its
location near the ear, is the largest, weighing from a half to
one ounce. It occupies the space in front of the ear, bounded
below by the angle of the jaw, and a line extended from it to
the mastoid process, above by the zygoma, in front by the
masseter muscle, and behind by the mastoid process, the exter-
nal meatus and the digastric muscle. The external carotid
artery, the temporomaxillary vein, the facial nerve and the
great auricular nerve pass through it.

The duct of the parotid gland (ductus parotideus [Steno-
nis~\), Steno's or Stenson's duct, empties its secretion into the
mouth. It is about two and a half inches in length, of the
diameter of a crow's quill, and crosses the face upon the mas-
seter muscle, through the substance of the buccinator muscle,
in the direction of an imaginary line drawn about a finger's
breadth below the zygoma, from the lower part of the ear to
midway between the ala of the nose and the margin of the upper
lip, to open about the position of the second molar tooth of the
upper jaw.

Its arteries are branches of the external carotid. The
veins empty into the external jugular. The lymphatics empty
into the superficial and deep cervical glands, and the nerves are
derived from the facial, from the superficial temporal branches
of the great auricular, the auriculotemporal ami sympathetic.

The submaxillary gland (glandula submaxillaris) occupies
the submaxillary fossa on the inferior surface of the inferior
maxilla, within the submaxillary triangle of the neck. Tbc
facial artery grooves itfl upper and posterior border, ami if is

separated behind from the parotid .gland by the stylomaxillary
ligament. The dud of the submaxillary gland, or Wharton's
dud (ductus submaxUlarw [Whartoni]), aboul two inches in
length, passes forward between the hyoglossus, geniohyoglossue

230 HUMAN ANATOMY. .

and mylohyoid muscles, to open at the side of the frsenum linguae
in a small papilla {caruncula sublingualis).

Its arteries are from the facial and lingual; the veins fol-
low the course of the corresponding arteries; the nerves are
from the submaxillary ganglion, the sympathetic and the my-
lohyoid branch of the inferior dental.

The sublingual gland (glandula sublingualis) , the smallest,
lies on the floor of the mouth, at the side of the frsenum linguae,
beneath the mucus membrane. Its ducts, called the ducts of
Eivinus (ductus sublingualis minor es), from eight to twenty,
open on the mucous membrane. One of them, the longest,
called the duct of Bartholin (ductus sublingualis major), joins
Wharton's duct. Its arteries are from the submental and sub-
lingual. The nerves are branches from the gustatory.

Besides these glands, the mucous membrane of the mouth
is plentifully supplied with mucous glands.

The pharynx is a musculomembranous sac, extending
from* the basilar process of the occipital bone above to the level
of the fifth cervical vertebra or the cricoid cartilage below. It
is about four and a half inches in length. It has communicat-
ing with it seven openings : —

Two posterior nares, Larynx,

Two Eustachian tubes, Esophagus,

Mouth.

It is composed of three coats :— .

1. Fibrous coat, or pharyngeal aponeurosis, attached above
to the pharyngeal spine of the basilar jtrocess of the occipital
bone ; it affords attachment in the median line to the constrictor
muscles of the pharynx.

2. Mucous coat (tunica mucosa), continuous with that of
the various openings. It is covered in its upper part with
columnar ciliated epithelium, as low as the floor of the nares,
below which it is squamous. It contains numerous racemose
glands (glandules pharyngeal), crypts, and" lymphoid structure
similar to the tonsils, a mass of which, between the Eustachian
tubes, has been called the "pharyngeal tonsil."

3. Muscular coat (tunica muscularis pharyngis), consists
of the three pharyngeal constrictors, the palatopharyngeus and
the stylopharyngeus. (Vidje Muscles.)

Arteries are from the inferior palatine, pharyngeal and
thyroid arteries. Nerves are branches of the pneumogastric,
glossopharyngeal and sympathetic.

THE ALIMENTARY APPARATUS.

231

The esophagus, or cili.ht. is a museulomembranous tube
about nine inches long and less tban one inch in diameter, flat-
tened from before backward, and extending from the pharynx to
the stomach or from the level of the fifth cervical to the ninth

dorsal vertebra.

Relations. — In the nock the trachea is in front, the common carot-
ids on either side, and in the chest the pericardium, the left carotid,

Fig. 88.

Pharynx laid open from behind: 1, styloid process; 2, body of

; Ital bone; :;, septum nasi; 1, middle turbinated bone; 5, posterior

naris; f,. inferior turbinated bone; 7, soft palate; !t, uvula; 10, tonsil;

11, bach ol tongue; 12, epiglottis; 13, arytenoepiglottidean fold; 14 tip

of arytenoid cartilage; 15, esophagus; 16, back of cricoid, cartilage.

lefl subclavian, the aorta ami the lefl bronchus are in front; the longua

'"Hi mUBCle and the intercostal vessels and the vertebra] column are

behind. The pleura covers it laterally, the descending portion of the
arch of the aorta tying on the left ami the vena azygos major on the
right.

It- structure consists of three coats: —
Muscular cat (tunica muscularis) , consisting of two layers,
the longitudinal and the circular, continuous with the inferior
! rictor:

232

HUMAN ANATOMY.

Areolar or fibrous coat (tela submucosa), connecting the
two;

Mucous coat (tunica mucosa), covered with stratified pave-
ment epithelium, and having beneath it some non-striated mus-
cular fibers, the muscularis mucosae. It also contains numerous
compound racemose glands, namely, the esophageal glands.

1, left hypochondriac region; 2, epigastric; 3, right hypochon-
driac; 4, left lumbar; 5, umbilical; 6, right lumbar; 7, left iliac;
8, hypogastric; 9, right iliac.

THE ABDOMEN.

The abdomen, the largest cavity in the body, is bounded
in front and laterally by the abdominal muscles, the lower ribs,
the ilii, above by the diaphragm, below by the brim of the pelvis,
and behind by the vertebral column, quadratus lumborum and
psoas muscles. It is lined throughout by peritoneum, inclosing
the greater portion of the alimentary canal. It has six openings,
as follows: —

Aortic opening, for the vena azygos, aorta and thoracic duct;
Esophageal opening, for the esophagus and pneumogastric nerves;
Quadrate opening, for the vena cava inferior;

THE ALIMENTARY APPARATUS.

233

Umbilicus, in front, for the fetal umbilical vessels;
Femoral canal [vide femoral hernia);

Inguinal canal, for the round ligament in the female, and the sper-
matic cord in the male.

Regions of the Abdomen. — For convenience of study, the
cavity of the abdomen is divided into nine regions by four
imaginary lines, two circular lines drawn around the body, one
at the lower margin of the thorax (Leidy) or on a level with
the cartilages of the ninth rib, the second at the highest point
of the crest of the ilium; and two vertical lines, drawn from
the cartilage of the eighth rib on each side through the center
of Poupart's ligament, or from the anterior inferior spinous
process of the ilium, drawn upward (Leidy). These regions
arc named as follows: —

Right hypochondriac,

Right lumbar,

Right inguinal (iliac),

High t Hypochondriac.
Hepatic flexure of
colon, right lobe of
liver, gall-bladder and
upper part of right
kidney.

Right Lumbar.
Greater part of right
kidney, ascending co-
lon and portions of

the small intestine.

Right Inguinal (Iliac).
Right ureter, cecum,
•pelmatic vessels and
appendix ceci.

Epigastric region,
Umbilical region,
Hypogastric region,

Contents of Regions.

Umbilical.
Left lobe of liver,
lobulus Spigelii,
greater part of stom-
ach, duodenum, pan-
creas, portions of the
kidneys and supra-
renal capsules, vena
cava, aorta, thoracic
duct, semilunar gan-
glia.

Um bilical.
Transverse portions
of colon and duode-
num, jejunum, and
ileum, part of mesen-
tery and great omen-
tum, receptaculum
chyli and portions of
both kidneys.

Hypogastric.

Portions of the small
intestine under cer-
tain circumstances,
the uterus ( preg-
nant), bladder (dis-
tended), sometimes
the cecum, sigmoid

flexure and appendix.

Left hypochondriac,

Left lumbar,

Left inguinal (iliac),

Left Hypochondriac.
Splenic flexure of
colon, spleen, tail of
pancreas, splenic end
of stomach and upper
part of left kidney.

Left Lumbar.
Part of left kidney,
descending colon, some
convolutions of small
intestine and part of
the omentum.

Left Inguinal (Iliac).
Left ureter, sigmoid
flexure "t' colon and
spermatic vessels.

234 HUMAN ANATOMY.

Peritoneum (tunica serosa). — The peritoneum is a closed
serous sac, its parietal layer (perilotmum parietale) lining the
cavity of the abdomen, its visceral layer (peritonceum viscerale)
inclosing more or less completely all the abdominal and pelvic
viscera. It is not in all cases a closed sac, for in the female it
is continuous with the mucous membrane of the Fallopian tubes.
It consists essentially of two sacs of unequal size, the greater
and lesser peritoneal sacs, united by a central constriction — the
foramen of Winslow: —

The greater sac is located in front of the viscera, one layer
lining the internal abdominal wall, the other reflected upon the
viscera. Its cavity is known as the greater peritoneal cavity.

The lesser sac covers the upper part of the posterior abdom-
inal wall, and is reflected upon the posterior surface of the liver
and stomach. Its cavity is called the lesser peritoneal cavity.
It also gives off three processes, one of which is a broad, loose
fold, — the great omentum (omentum majus), — passing down-
ward from the greater curvature of the stomach between the
two layers of the greater sac, and is reflected upon itself back
to the under surface of the transverse colon.

The foramen of Winslow (foramen epiploicum [Winsloivi])
is a narrow canal, large enough to admit one finger, between
the greater and ksser peritoneal cavities, located behind the
right border of the lesser omentum, and formed by the hepatic
and gastric arteries, constricting the sac at this point as they
ascend from the celiac axis. It is bounded as follows : —

In front, by the lesser omentum, containing the hepatic artery,
portal vein, duodenum and the ductus communis choledochus;

Behind, by the right crus of the diaphragm and the inferior vena
cava;

Above, by the lobus Spigelii;

Below, by the hepatic artery.

Reflections. — The reflections of the peritoneum viewed in
an anteroposterior section (the greater and lesser sacs together)
may be traced as follows : From the diaphragm it is reflected to
the upper surface of the liver. Enveloping this organ it then
presents a doubling or fold — the gastrohepatic omentum — ex-
tending downward from the transverse hepatic fissure to the
lesser curvature of the stomach. Inclosing the stomach, it is
reflected upon itself in front of the intestines as a broad apron
■ — the great omentum (omentum majus) — making a quadruple
fold off peritoneum.

The two layers then embrace the transverse colon, unite
and pass back to the vertebral column, forming the transverse

THE ALIMENTARY APPARATUS.

235

Fig. 90.
The abdominal viscera. {Schley.)

236

HUMAN ANATOMY.

mesocolon (mesocolon transversum) . From here the layers
separate, the upper one ascending in front of the pancreas to
the starting point. The lower layer descends in front of the
duodenum, incloses the small intestine — forming the mes-
entery proper — (mesenterium) , is reflected upon the rectum —

Fig. 91.

D, diaphragm,; L, liver; S, stomach; P, pancreas; D, duodenum;
C, colon; I, small intestine; B, bladder; R, rectum; 3, posterior
surface of liver; 4, foramen of Winslow; 5, great omentum; 6,
lesser omentum; 7, mesocolon; 8-9, lesser cavity of peritoneum; 10,
mesentery; 11, rectovesical fold.

forming the mesorecrum — and upon the bladder, and ascends
upon the anterior abdominal wall to the starting point.

In the female, from the rectum it envelops the uterus and
upper part of the vagina before reaching the bladder.

In addition to the folds seen in the anteroposterior section,
the peritoneum passes between the various organs, and also lat-
erally to the sides of the abdominal and pelvic cavities. In this

THE ALIMENTARY APPARATUS. 237

manner are formed the right lateral (ligamentum triangulare
dextrum), left lateral (ligamentum triawgulare sinistrum) , and

suspensory ligaments of the liver (ligamentum falciforme hep-
atis), the suspensory ligament of the spleen (ligamentum
phrenicolienale) , the broad ligament of the uterus (ligamentum
latum uteri), and the three ligaments or omenta of the stomach
— the gastrohepatic (omentum minus), gastrosplenic (ligamen-
tum gastrolienale) , and gastrocolic (omentum majus) (already
described) and the mesenteries.

The latter, the mesenteries, include the mesentery proper,
mesocecum ; ascending (mesocolon ascendens) , transverse (meso-
colon transversum ) . and descending mesocolon (mesocolon
descendens), sigmoid mesocolon (mesocolon sigmoideum) and,
mesorectum.

The mesentery proper (mesenterium) is a broad fold, re-
flected from the vertebras around the jejunum and ileum. Its
base, attached obliquely from the left side of the second lumbar
vertebra to the right iliac region, measures about six inches,
while its expanded extremity is quite considerable.

In the male the rectovesical folds, one on each side, pass
from the rectum to the bladder, including between them the
rectovesical pouch (excavatio rectovesical) . In the female,
however, this pouch is divided into two — the rectouterine and
vesicouterine pouches (excavatio vesicoaterina), the rectovesical
folds being called rectouterine and vesicouterine folds (plica
rectouterine^) . Folds of peritoneum (superior false ligaments
of the bladder) (plicce umbilicalis media) ascend from the blad-
der to the umbilicus, inclosing the remains of the fetal urachus
(ligamentum umbilicale medium) and hypogastric arteries, and
also a fold on each side follows the course of the epigastric
arteries toward the umbilicus, dividing the inguinal region into
the internal, middle and external inguinal fossa?. The peri-
toneum at the external inguinal fossa (corresponding to the
internal abdominal ring) is continuous in the male fetus with
the tunica vaginalis testis, and in the female forms a blind sac
about the round ligament — the canal of Nuck.

Viscera Partly Invested by Peritoneum.

Vagina upper part;

Bladder posterior wall;

Duodenum — descending and transverse portions;

Cecum :

Colon ascending and descending;

Bed inn — middle porl ion.

238 HUMAN ANATOMY.

Viscera Entirely or Almost Entirely Covered.

Stomach, Sigmoid flexure,

Spleen, Rectum — upper part,

Ileum, Liver,

Jejunum, Uterus,

Colon — transverse Ovaries.

Viscera Without Peritoneal Investment

Bladder — except posterior wall;

Rectum- — lower third;

Vagina — lower part of posterior wall;

Pancreas,

Suprarenal capsules, J- partly covered anteriorly.

Kidneys,

THE STOMACH.

The stomach (ventriculus) is a musculomembranons sac,
pyriform in shape, situated below the diaphragm in an oblique
position across the upper abdomen, where it is held in position
by the lesser omentum and the gastrosplenic ligament. It
measures about nine to twelve inches in length, four to five
inches in its greatest diameter, and has a capacity of from one
to two quarts. It occupies the epigastric, right and left hypo-
chondriac regions, and is in relation above with the diaphragm
and liver, below with the transverse colon, in front with the ab-
dominal walls, and behind with the pancreas. When distended
the stomach rotates on its long axis and the greater curvature
points somewhat forward. It presents for examination a greater
and lesser extremity, greater and lesser curvatures, anterior and
posterior surfaces, and cardiac and pyloric orifices.

The greater extremity, or fundus (fundus ventriculi), oc-
cupies the left hypochondriac region, in contact with the spleen,
with which it is attached by the gastrosplenic omentum, and
behind the lower rib.

The lesser or pyloric end is smaller and lies in contact with
the under surface of the liver and the wall of the abdomen in
the right hypogastric region.

The greater curvature (curvaturd ventriculi major) extends
between the pyloric and esophageal orifices, along the lower
border of the stomach, and to it is attached the great omentum.

The lesser curvature (curvatura ventriculi minor) extends
between the same two points along the superior border of the
organ.

THE ALIMENTARY APPARATUS. 339

The esophageal or cardiac orifice occupies the highest part
of the stomach, behind the seventh left costal cartilage, and
receives the esophagus.

The pyloric orifice occupies the right extremity, and opens
into the duodenum, being protected by a muscular valve, the
pylorus, or pyloric valve (valvula pylori).

The anterior, upper or parietal surface (paries anterior) is
in contact with the under surface of the left lobe of the liver,
the abdominal walls and the diaphragm.

The posterior, lower or visceral surface (paries posterior)
is in contact with the peritoneum of the diaphragm, solar
plexus, the pancreas and the abdominal vessels.

The structure of the stomach consists of four coats, a se-
rous, muscular, fibrous or areolar and mucous.

The serous coat (tunica serosa) is derived from the peri-
toneum, which completely covers it, except along the lesser and
greater curvatures, where the vessels and nerves enter.

The muscular coat (tunica muscularis) consists of three
sets of fibers :— -

The longitudinal (stratum longitudinale) , the most super-
ficial, are continuous with the longitudinal fibers of the small
intestine below, and the esophagus above;

The circular fibers (stratum circulare), the second layer,
are most abundant at the pyloric extremity, where they form
the pyloric valve (valvula pylori).

The oblique fibers (fibres obliques) are distributed over both
surfaces, passing obliquely from right to left and left to right.

The areolar or submucous coat (tela submucosa) connects
the muscular with the mucous layer, and is sometimes named
the vascular coat.

The mucous membrane (tunica mucosa) is of a pale pink-
ish-ash color, thickened toward the pylorus, where it presents
numerous rugae, or pleats (plica mucosal), and at the pyloric
end it helps to form the pyloric valve. It is lined throughout
with columnar epithelium, and is studded with three kinds of
minute tubes, the gastric follicles and lenticular glands. The
gastric follicles consist of two kinds, the pyloric (glandulcB
pyloricce) and the peptic glands (glandular gastricoB propria),
the former most abundant at the pyloric end and the latter
distributed all over the surface of the Btomach.

The pyloric or mucous glands (glandvlm pyloricce) each
consisl of from two to lour blind tubes opening into a common
duct, and lined throughout by columnar epithelium.

240 HUMAN ANATOMY.

The peptic glands {glandular gstricce proprice) are similar
in structure, but have a much shorter duct, and contain in addi-
tion peculiar large, spheroidal, granular peptic cells.

The lenticular or simple solitary glands {nocluli lymphatici
solitarii) are small masses of lymphoid tissue scattered through-
out the connective-tissue framework of the stomach between the
gastric follicles.

The arteries are derived from the gastric, pyloric, right
gastroepiploic branches of the hepatic artery, and the left gas-
troepiploic and vasa brevia branches of the splenic artery {vide
Arterial System).

The veins terminate in the portal, superior mesenteric and
splenic veins.

The nerves are derived from the gastric plexuses (A.uer-
bach's and Meissner's plexuses, in the muscular and submucous
coats, respectively), formed by the terminal branches of the
right and left pneumogastric, and the branches of the celiac
plexus, an offshoot of the solar plexus of the sympathetic.

THE SMALL INTESTINE (iNTESTINUM TENUE).

The small intestine is a convoluted tube about twenty to
twenty-five feet in length, for the chylification of the food,
occupying the lower and central portions -of the abdominal and
pelvic cavities, and held in position to the spinal column by the
mesentery. It is divided into three portions — the duodenum,
jejunum and ileum.

The duodenum, so called from being in length about
twelve fingers' breadth, is about eight to ten inches long. It
consists of four portions, from the position of its course —
ascending, descending, transverse and terminal ascending: —

The first, ascending or superior portion {pars superior) is
about two inches in length, and ascends to the neck of the gall-
bladder. It is completely invested by peritoneum for about an
inch.

The second or descending portion {pars descendens) , about
three inches in length, descends in front of the right kidney as
far as the third or fourth lumbar vertebra, and is overlapped
in front by the head of the pancreas, and into its posterior
aspect, the duct of the pancreas and the common biliary duct
open by a common orifice.

The third,' preaortic, horizontal or transverse portion is
attached to the crura of the diaphragm and the vessels in front
of the vertebral column, passes behind the transverse mesocolon,

THE ALIMENTARY APPARATUS. 341

and has the pancreas above it, while the superior mesenteric
blood vessels cross from beneath the latter between the two, or
over the duodenum.

The fourth or terminal ascending portion (pars ascendens)
runs upward and forward to the duodenojejunal flexure.

The arteries are derived from the inferior pancreatico-
duodenal branch of the superior mesenteric and the superior
pancreaticoduodenal branch of the gastroduodenal, a branch of
the hepatic. The veins terminate in the superior mesenteric
and splenic veins. The nerves are from the solar plexus.

The jejunum (intestinum jejunum), named from jejunus^
empty, includes the upper two-fifths of the small intestine, is
continuous above with the duodenum and below with the ileum.
It occupies chiefly the left iliac and umbilical region.

The ilki'.m (intestinum ileum), so called from its twisted
appearance, includes the remaining three-fifths, is continuous
above with the jejunum and below with the caput cecum of the
large intestine. It occupies the right iliac, hypogastric and
umbilical regions.

The structure of the small intestine consists of four coats —
the serous, muscular, fibrous or areolar and mucous : —

The serous coat (tunica. serosa) is the peritoneal covering;

The muscular coat (tunica muscularis) consists of two sets
— a Longitudinal and a circular;

The areolar or submucous coat (tela submucosa) connects
the muscular with the mucous coat;

The mucous coat (tunica mucosa) is thinner and redder
than that of the stomach, and is thrown into numerous trans-
verse folds — the valvulae conniventes — most numerous in the
upper part; they diminish as it descends and finally disappear
in the ileum. They increase the secreting and absorbing surface
of the mucous membrane and retard the passage of the food.

The mucous membrane also contains the villi and four
kinds of glands: —

Simple follicles, or crypts of Lieberkiihn;
Duodenal glands, or Brunner's glands;
Solitary glands;
Agminate, or Fever's glands.

The villi (villi iulcsliiinles) are minute vascular projec-
tion- of the mucous membrane scattered throughout the surface
of the small intestine. Their structure consists of a pouch-like
termination of a lacteal in the center, surrounded by a minute
plexus of capillary vessels, inclosed in a basement membrane ami
covered with columnar epithelium.

ie

24:2 HUMAN ANATOMY.

The simple follicles, or crypts of Lieberkiihn (glandules
intestinales [Lieberkiihnt]) , are scattered throughout the mu-
cous membrane of the entire small intestine. They consist of
minute tubes of basement membrane, lined with columnar epi-
thelium and surrounded by a capillary network.

The duodenal or Brunner's glands (glandulce duodenales
[Brunneri] ) are distributed to the doudenum and jejunum
only. They are largest and most numerous in the vicinity of
the pylorus. They are composed of tubular alveoli, lined by
epithelium, and having a small duct opening on the mucous
membrane.

The solitary glands (noduli lymphatici solitarii) are dis-
tributed throughout the small intestine, being most numerous
in the last portion of the ileum. They consist of lymph folli-
cles, and communicate with the lacteal system by means of
lymph spaces.

Peyer^s glands, or Peyer's patches (noduli lymphatici ag-
gregati [Peyeri] ) , consist of an aggregation of the solitary
glands into oval groups of twenty or thirty, along the small
intestine at a point opposite the attachment of the mesentery.
The patches are about fifteen to thirty in number, each meas-
uring about one-half to two inches in length and one-half inch
in breadth. Their axes are parallel with the length of the
intestine. In the duodenum they are few and small in size, and
the mucous membrane of the valvulse conniventes over them is
reduced in size and much distorted.

The arteries are derived from the pyloric, pancreatico-
duodenal and superior mesenteric. They reach the intestines
inclosed in and along the course of the mesenteries. In the
intervals of the coats they form three vascular nets, which sup-
ply the serous, muscular and mucous coats. The veins accom-
pany the arteries and join the portal vein.

The lymphatics follow the course of the superior mesenteric
vessels to enter the mesenteric glands.

The nerves are derived from the solar plexus of the sym-
pathetic.

THE LARGE INTESTINE (iNTESTINUM CRASSUM).

The large intestine is about five feet long and extends from
the ileum to the anus.

It commences in the right iliac fossa, ascends through the
right lumbar and right hypochondriac regions, passes trans-
versely between the epigastric and umbilical regions to the left

THE ALIMENTARY APPARATUS. 243

hypochondriac region, where it descends through the left hypo-
chondriac, lumbar and iliac regions, and through the pelvis on
its posterior wall to terminate at the anus.
It consists of three divisions: —

1. Cecum.

f Ascending,
9 pi j Transverse,

Descending,
[ Sigmoid flexure.

3. Rectum.

The cecum (in-testinum cn'cum) is a blind pouch measur-
ing about two and one-half inches in every diameter, lying free
in the right iliac region.

It has opening into its lower back part the appendix vermi-
formis, and into its inner back part the ileum, guarded by the
ileocecal valve.

The appendix vermiformis {processus verm-iformifi) is a
long, narrow, twisted tube, the rudiment of the prolonged cecum
in all mammalia. It terminates in a blunt extremity. Its
mucous membrane is continuous with that of the cecum, and
contains many solitary glands.

The ileocecal valve (vulvula coli), or valve of Bauhin, pro-
tects the opening of the ileum into the cecum, and consists of
two valve-like semilunar folds of mucous membrane, strength-
ened by bands of circular fibers. The upper one is attached to
the junction of the ileum with the colon, the lower one to the
junction of the ileum with the cecum. On each side where the
folds coalesce, a ridge of mucous membrane, continuous for a
short distance around the canal, forms, the frenulum or retinac-
ulum (frrniini valvules coli) of the valve. The mucous mem-
brane on either side of the valves corresponds to that of the
large and small intestines respectively, being covered with villi
on the side toward the ileum, and being destitute of villi, and
containing numerous tubular glands or crypts of Lieberkiibn, on
the Bide toward the cecum. This difference occurs abruptly at
the free margin of the valves.

The COLON consists of four portions — ascending, trans-
verse, and descending colon and sigmoid flexure: —

The ascending portion (colon ascendens) begins opposite
the ileocecal valve, ascends through the right lumbar and hypo-
chondriac regions, and terminates beneath the under Burface of
the liver at the hepatic flexure (flexura coli dextra) in the
transverse portion. Its posterior surface is destitute of peri-

244 HUMAN ANATOMY.

toneum, and is attached to the quadratus luniborum muscle by
loose areolar tissue.

The transverse portion, or transverse arch of the colon
(colon transversum) , passes from the hepatic flexure, through
the adjoining portions of the epigastric and umbilical regions,
to terminate at the splenic flexure (flexura coli sinistra) in the
descending portion. It is attached by transverse mesocolon, and
is the most movable portion of the colon.

The descending portion (colon descendens) begins at the
splenic flexure, descends through the left lumbar and iliac
regions to terminate in the sigmoid flexure. Like the ascending
colon, its posterior surface is destitute of peritoneum.

The sigmoid flexure — omega loop — (colon sigmoideum) is
a narrow, twisted portion of the colon, occupying the left iliac
fossa, between the descending portion of the colon and 'the rec-
tum. It is held in position by the sigmoid mesocolon. It
terminates opposite the third sacral vertebra.

The rectum (intestinum rectum) — the terminal portion
— extends from the sigmoid flexure to the anus. It is four to
six inches in length, not sacculated, but club-shaped, with its
large extremity downward, and consists of two portions — supe-
rior and inferior: —

The lower four inches, formerly described as the upper por-
tion of the rectum, rest upon the sacral plexus of nerves and
the pyriformis muscle;

The superior portion, about three and three-quarters inches,
is in relation in the male with the bladder, prostate gland and
vesiculse seminalis; in the female with the uterus and vagina,
being adherent to the latter ;

The inferior portion, about one and one-quarter inches,
turns backward and terminates in the anus. It is supported by
the levator ani muscle, and is surrounded by the internal and
external sphincters of the anus. The structure of the large
intestine consists of four coats — serous, muscular, cellular and
mucous : —

The serous coat (tunica serosa), derived from the perito-
neum, invests completely the transverse and sigmoid portions of
the colon, but only partially the others, being absent in the pos-
terior surfaces of the ascending and descending portions, and
on the superior part of the rectum. The inferior surface of the
rectum is without peritoneal covering. The appendices epi-
ploicce are folds of serous membrane filled with fat and attached
chiefly to the transverse colon.

THE ALIMENTARY APPARATUS. 245

The muscular coat (tunica muscularis) consists of longi-
tudinal fibers arranged into three flat bands, shorter by nearly

one-half than the intestine itself, and the circular, distributed
more evenly, but accumulated at points, producing with the
former a sacculated condition.

The cellular coat connects the mucous with the muscular
coat beneath.

The mucous coat (tunica mucosa) is smooth, destitute 01
villi and valvulae conniventes, and thrown into numerous folds,
two to four of which, situated in the rectum, have_ received the
name of Houston's valves (plica? transversal es recti).

It contains crypts of Lieberkulm, more numerous here than
in the small intestine, and solitary glands scattered throughout,
but most numerous in the appendix and cecum, where some of
them are accumulated into Peyer's patches.

The arteries of the cecum and colon are from the mesen-
teric. The lymphatics empty into the mesenteric glands, and
the nerves are derived from the mesenteric plexus of the sym-
pathetic system.

The arteries of the rectum are the hemorrhoidal branches
of the inferior mesenteric, internal iliac and internal pudic.
The veins form the hemorrhoidal plexus, and empty into the
inferior mesenteric and internal iliac veins.

The lymphatics go to the sacral and lumbar glands, and the
nerves are from the hypogastric plexus of sympathetic and con-
tiguous spinal nerves.

THE PANCREAS.

The pancreas is an oblong, compound, racemose gland,
about six to eight inches in length, one and one-half inches in
breadth, and one-half to one inch in thickness, situated across
the back part of the epigastric and left hypochondriac regions.
In weight varies from two to six ounces.

It consists of a head, body and tail : —

The head (caput pancreatic), or right extremity, is received
int., the concavity of the duodenum. The 'lesser pancreas, a
detached portion of the gland, lies behind it.

The tail, or lesser nnl, terminates above the left kidney
and suprarenal capsule, in contact with the spleen.

The body (corpus paw-real is) is in relation in front with
the stomach ami transverse mesocolon; behind it rests upon the
first lumbar rertebra, having interposed the crura of (he dia-
phragm, \ena cava, left renal win, aorta, superior mesenteric

2^6 HUMAN ANATOMY.

artery and vein, the inferior mesenteric vein and commence-
ment of portal vein.

The splenic artery and vein are lodged in a groove on its
upper border.

The pancreatic duct, or canal of Wirsung (ductus pan-
creations [Wirsungi~\) , runs throughout the substance of the
organ, to emerge at the head, and open into the duodenum by
an orifice in common with the ductus communis choledochus.
The lesser pancreas, when it exists, empties by the ductus pan-
creaticus minor.

The structure resembles that of the salivary glands, but is
softer and looser.

Arteries are from the splenic and pancreaticoduodenal
branches of the hepatic and superior mesenteric.

The veins join the splenic or superior mesenteric.

The nerves are from splenic plexus of the sympathetic.

The lymphatics empty into the lumbar glands.

THE LIVER (HEPAR).

The liver is the largest gland in the body, measuring in
its transverse diameter from ten to twelve inches, and its antero-
posterior six to seven, and its thickest part about three inches,
and weighing about from three to four pounds. It occupies
the upper part of the abdominal cavity, and the right hypo-
chondriac, epigastric, and a portion of the left hypochondriac
regions. Its upper surface is convex and rests against the dia-
phragm and a small portion of the abdominal parietes in front.
Its lower, or visceral surface (fades inferior), is in contact with
the duodenum and stomach, the right kidney and suprarenal cap-
sules, and the hepatic flexure of the colon. It is divided by the
longitudinal fissure into the right and left lobes (lobuli hepatis) .
The liver has five fissures, five lobes, five ligaments, five sets of
vessels, and is inclosed in a fibrous coat, continuous at the trans-
verse fissure with the capsule of Glisson. It is also invested by
the peritoneum, except at the attachment of the coronary liga-
ment.

Structure. — The liver is made up of lobules, which are
small, granular bodies about one-fifteenth of an inch in diam-
eter, held together by delicate connective tissue and the branches
of the five sets of vessels (to be described) and nerves, the whole
being inclosed in a serous and fibrous coat.

Each lobule is made up of a mass of polyhedral, nucleated
fells, inclosed in a capillary plexus derived from the hepatic

\

THE ALIMENTARY APPARATUS.

;m;

artery and portal vein, and giving origin to the hepatic vein
and biliary duct.

The five fissures of the liver are all situated on its under
surface. They separate the five lobes from one another. They
are : —

1. Longitudinal fissure (fossa longitudinalis sinistra) ex-
tends from before backward, from the notch in front to the
posterior border. It is sometimes called the umbilical fissure
(fossa vencB umbilicalis) , and lodges the round ligament, the
remains of the fetal umbilical vein.

2. Fissure for the ductus venosus (fossa ductus venosi) is

u

^#\

x_

Fig. 92

1, left lobe; 2, right lobe; 3, quadrate lobe; 4, caudate _lflhg; 5,
Spigelian lobe; 6, hepatic artery; 7, portal vein; 8, Assure of ductus
venosus; 9, gall-bladder; 10, cystic duct; 11, hepatic duct; 12, fissure
for vena cava; 13, vena cava; 14, right inferior phrenic vein; 15,
hepatic vein; 16, right renal vein; 17, left renal vein.

the posterior portion of the longitudinal fissure, and lodges the
remains of the ductus venosus of fetal life.

:;. Transverse fissure, or portal fissure (porta hepatic),
- the inferior surface of the liver transversely ami joins
the Longitudinal. It transmits the portal vein, hepatic artery
and nerves, and the hepatic duct and lymphatics.

I. Fissure for the gall-bladder (fossa vesica- frllea?) is ?
shallow depression beneath the right lobe, running parallel wit'
the longitudinal fissure in front.

Fissure for the vena cava (fossa venm cava?) runs obliq1 ly
upward along the inferior surface oear its posterior marg to

248 HUMAN ANATOMY.

the left side, joining the fissure for the ductus venosus behind,
and separated from the transverse fissure in front by the lobulus
caudatus. It lodges the inferior cava, which, within this fissure,
receives the hepatic veins.

The five lobes of the liver are : —

Eight lobe {lotus liepatis dexter), much the largest, is
somewhat quadrilateral in outline, and presents three fissures
and two depressions, the latter one for the right kidney and its
suprarenal capsule, and the other for the hepatic flexure of the
colon.

Left lobe (lobus liepatis sinister), smaller, is separated

Fig. 93.

Transverse section of lobules of liver: (a), interlobular vein; (&),
intralobular central vein.

from the right lobe by the longitudinal fissure, and is in con-
tact with the stomach.

Lobulus quadratus, or square lobe, occupies the anterior
border of the under surface of the right lobe, between the um-
bilical fissure and the fissure for the gall-bladder, and in front
of the transverse fissure.

Lobulus Spigelii {lobus caudatus [Spigeli]) occupies a
similar position to the quadrate lobe, along the posterior bor-
der, immediately back of it, from which it is separated by the
transverse fissure. It is bounded laterally by the fissures for
the ductus venosus and vena cava.

Lobulus caudatus, or tailed lobe, unites the lobus Spigelii
with the right lobe, and separates the transverse fissure from
the fit nre for the vena cava.

THE ALIMENTARY APPARATUS. 249

The five ligaments of the liver are folds of peritoneum
except one, the "round ligament, which is the remains of the
umbilical vein and ductus venosus of the fetus.

They are: —

1. Longitudinal or falciform ligament (ligamentum fahir
forme hepatis) consists of two layers of peritoneum, attached
by one margin to the under surface of the diaphragm, and the
sheath of the right rectus muscle, and is attached to the liver
along its anterior margin, from the notch to its posterior border.

2 and 3. The lateral ligaments (ligamenta triangulare dex-
trum ct sinistrum) , one on either side, are triangular layers of
peritoneum, attached to the lateral edges of the liver toward
its posterior margin.

4. The coronary ligament (ligamentum coronarium hep-
atis) is formed of two layers, continuous with the lateral liga-
ment and with the longitudinal ligament, connecting the pos-
terior border of the liver to the diaphragm.

5. The round ligament (ligamentum teres hepatis) is a
fibrous cord, the remains of the obliterated umbilical vein and
ductus venosus, extending from the umbilicus to the longi-
tudinal fissure, extending as far back as the inferior vena cava.

The five sets of vessels are the hepatic artery, portal vein,
hepatic veins, hepatic ducts and lymphatics: —

The hepatic artery, the nutrient vessel of the liver, one of
the branches of the celiac axis, enters the transverse fissure, and
after giving off branches to the capsule of Grlisson (capsula
fibrosa [Glissoni]), and to the capsule, divides into interlobular
branches, which form plexuses around each lobule, and ter-
minate in capillaries between the cells, anastomosing with the
capillaries of the portal vein.

The portal rein enters at the transverse fissure, divides into
two branches, and finally terminates in the interlobular plexuses,
already described. These all unite into one vein — intralobular
vein — -traversing the center of the lobule to join the sublobular
nil,, the latter ending in the hepatic veins. These latter finally
terminate in the inferior vena cava.

The hepatic ducta (ductus ln'/iaticus) originate between the
hepatic cells as bile capillaries, minute canals without walls, and
form a plexus between the lobules. From these plexuses ductf
eonverge and unite to finally form the hepatic duct.

The lymphatic vessels form two sefs — the superficial, th e
upon the surface of the organ; and deep, those accompaspv ug
the branches of the bepatic arteries and portal vein.

250 HUMAN ANATOMY.

The gall-bladder (vesica fellea) is a conical membranous
sac attached to the under surface of the right lobe of the liver,
and partly covered by peritoneum. It measures about four
inches by one, and has a capacity of about nine drachms. It
consists of a fundus (fundus vesicce fellece), or rounded extrem-
ity, a body (corpus vesicce fellece) and neck (collum vesicce
fellece), and has three coats — a fibrous, muscular and mucous —
the latter lined with columnar epithelium.

The neck terminates in the cystic duct, the mucous mem-
brane of which is thrown into a series of folds, forming a spiral
valve.

The ductus communis choledochus (ductus choledochus) ,
or common biliary duct, about three inches long and the diam-
eter of a goose-quill, is formed by the union of the hepatic,
about two inches in length, and the cystic (ductus cysticus),
about one inch in length. It empties into the descending por-
tion of the duodenum in common with the pancreatic duct,
about three and one-half inches below the pylorus.

THE DUCTLESS GLANDS.

The following group includes the glands without ducts1
which resemble each other in structure : —

Spleen, Thymus,

Thyroid, Suprarenal capsules,

Pituitary body, G-landula coccygea,

Glandula intercarotica.

The Spleen (Lien). — The spleen is a soft, very vascular,
sponge-like organ, situated deeply in1 the left hypochondriac
region. It varies much in size and weight, measuring about five
inches in length, three in width, one and one-half in thickness,
and weighing between seven and ten ounces.

Outer surface (fades diaphragmatica) , smooth and convex,
corresponds to the ninth, tenth, and eleventh ribs, and is
adapted to the inferior surface of the diaphragm, to which it is
connected by the suspensory ligament.

Inner surface is concave and adapted to the cardiac end of
the stomach, to which it is attached by the gastrosplenic omen-

l Formerly it was taught that these glands were enigmatic in
natiae; more recently, however, it was discovered that they elaborate
subsr ices which are added to the blood and lymph, and which are
desigi- d "internal secretions." These internal secretions play a
domin; ; role in maintaining a balance in the economy.

THE ALIMENTARY APPARATUS. 251

Hilus (hilus lienis) is a vertical fissure on the concave
inner surface, admitting the passage of blood vessels, lymphatics
and nerves. The structure consists of two coats — a serous and
fibroblastic coat, inclosing in its interior the spleen pulp.

Serous coat (tunica serosa), derived from the peritneoum,
covers the entire organ, except at the hilus, where it forms the
gastrosplenic omentum.

Fibroblastic coat, or tunica propria (tunica albuginea), sur-
rounds the organ, and from the hilus and periphery sends
numerous fibrous bands, or trabecular (trabecule lienis), into
the substance of the organ, dividing it into small trabecular
spaces, or areola?.

Splenic substance, or spleen pulp (pal pa lienis), is a soft,
reddish-brown mass, consisting of a fine reticulum of connec-
tive-tissue corpuscles, inclosing red and white blood corpuscles,
nucleated and non-nucleated cells, granular matter, etc.

Malpighian corpuscles, or bodies (noduli lymphatici lien-
ales [Malpighii]), are spheroidal hyperplasia? of lymphoid tissue
from the outer coat of the arterioles. They are not encapsuled,
vary from one-sixtieth to one-twenty-fifth of an inch, and are
visible in the fresh specimens to the naked eye.

Splenic artery, remarkable for its size and tortuosity,
divides in the hilus into four or five branches, each distributed
to a segment, terminating in a capillary plexus without anasto-
moses, or opening directly into the areola? of the splenic pulp.

Splenic rein commences in the same manner as the arte-
rioles end, and empties into the portal vein. The smaller veins
anastomose freely.

Nerves are from the splenic plexus, formed from the right
pneumogastric nerve, and the left semilunar ganglion of the
solar plexus.

Thyroid Gland (glandula thyreoidea) . — The thyroid is a
vascular, gland-like body, situated on the sides of the upper part
lit' i he trachea, and consists of two lateral lotjes connected by a
transverse portion, the isthmus (isthmus glandules thyreoidea).

A third loin — the pyramid — sometimes arises from the left
lobe or upper margin of the isthmus.

Levator glanduke thyreoidea are muscular bands sometimes
found passing from the isthmus to the body of the hyoid bone.

Structure. — This is. similar to other glands, being made w
of a capsule and radiating septa inclosing alveoli the closf
resides — each of which is lined with one layer of colunr t
epithelium, and contains more or less viscid, transparent flu
the coftoid substance. The closed vesicles are abundantly up

252 HUMAN ANATOMY.

plied with blood by meshes of capillaries, while penetrating the
septa are lymphatic networks, and lymph sinuses are found in
the tissue between the vesicles and septa.

Arteries are the superior thyroid, a branch of external
carotid, and inferior thyroid, a branch of the thyroid axis, and
sometimes a branch from the arch of the aorta or innominate
artery, the middle thyroid, or arteria thyroidea ima. All the
vessels anastomose freely.

Veins form plexus about the gland and give off the superior
and middle thyroid to internal jugular, and inferior thyroid to
innominate vein.

Nerves, from middle and inferior cervical ganglia and from
pneumogastric.

Thymus Gland. — The thymus gland is a temporary organ
which attains its full size at the end of two years and at puberty
has almost disappeared. It occupies the upper part of the an-
terior mediastinum, and is in relation in front with the sternum,
and below with the pericardium, aorta, left innominate and
trachea. It is a flat, triangular body, composed of a pair of
lateral unequal lobes, about two inches in length, one and one-
half inches at the widest part, and one-quarter inch thick, and
weighing about one-half ounce.

Structure. — It is composed of a framework of fibroconnec-
tive tissue, consiting of a capsule, septa and gland substance,
which is divided, into lobes, these into lobules, and these latter
into units or follicles.

The follicles vary in shape, present for study a cortex and
medulla, and consist of adenoid tissue.

The cortical meshes of the reticulated adenoid tissue are
filled with lymph-corpuscles, while in the medulla the meshes
are less numerous and filled with large endothelioid plates and
giant cells.

The capillary blood-vessels surrounded the follicles.

Arteries are from superior and inferior thyroid and inter-
nal mammary.

Veins join thyroid and left innominate veins.

Nerves are from sympathetic and pneumogastric.

Suprarenal Capsules (glandulce suprarenalis) . — The su-
prarenal capsules are two small, triangular bodies, situated upon
the upper and front part of either kidney. They measure from
one ;;nd one-quarter to two inches in length, and less in breadth,
two lc three lines in thickness, and weigh about two drachms.

THE ALIMENTARY APPARATUS. 253

Structure. — Like the kidneys, they consist of a cortical and
medullary portion, inclosed in a capsule which sends septa into
the substance of the body.

The cortex (substantia corticalis) is composed of three
zones of epithelial cells — outer, middle and inner — the middle
being the largest.

The medulla (substantia medullaris) consists of streaks of
small, transparent cells, separated by connective tissue and capil-
laries. These streaks are continuous with the inner zone of the
cortex. The nerve supply is rich, consisting of non-medullated
fibers connected with small ganglia.

Relations. — The inferior concave border rests upon the upper sur-
face of the kidney. The inner border rests against the inferior vena
cava on the right side, the aorta on the left, and is in relation with semi-
lunar ganglion and great splanchnic nerves.

The anterior surfaces touch on the right the under surface of the
liver, and on the left side the pancreas and spleen. The posterior sur-
face lies upon the cms of the diaphragm, about opposite the tenth dorsal
vertebra.

Arteries are suprarenal from the aorta, the renal and
phrenic arteries.

Veins on the right join vena cava, on left renal vein.

Nerves, from renal and solar plexus.

Pituitary body (hypophysis cerebri) is a small, vascular
mass on the inferior surface of the cerebrum, but resembling in
structure the ductless glands.

Structure. — The upper lobe is part of the central nervous
system. The lower and larger lobe has a fibrous capsule which
sends processes into the interior, forming minute septa ; these
divide and reunite around spaces called alveoli. The alveoli
contain epithelial cells of various shapes, between which are
small irregular cells having flattened nuclei.

The glandula coccygea (glomus coccygeum), lying near
the tip of the coccyx, and the intekcarotica, or carotid gland
or body (glomus caroticwin) , at the angle of bifurcation of the
common carotid, have been recently included among the duct-
glands. They were both discovered by Luschka. The
framework of their bodies is identical with that of other glands,

excepl that the septa contain noii-st riped muscular tissue. The

alveoli are filled with gland substance, consisting of connected
masses of epithelial cells, having in their center a twisted capil-
lary blood vessels.

VOCAL AND RESPIRATORY APPARATUS.

The lartio; is a musculocartilaginous box at the top of
the trachea, below the root of the tongue and the hyoid bone,
and is the organ of the voice. It is composed of cartilages
(cartilagines laryngis) connected by ligaments, provided with
muscles, blood-vessels and nerves, and lined with mucous mem-
brane. The cartilages are nine in number, three single and
three pairs: —

Thyroid,

Cricoid,

Epiglottis,

Two arytenoid,

Two cornicula laryngis,

Two cuneiform.

The thyroid {cartilago thyreoidea) , the largest cartilage,
consists of two quadrilateral halves, united in front in the
median line, or entering angle of the thyroid, the upper part of
which is the pomum Adami {prominentia laryngea). The outer
surface is marked by an oblique ridge (linea obliqua) for the
attachment of muscles. The inner surface is smooth and cov-
ered by mucous membrane, and has in front attached the true
and false vocal cords. The posterior angles are prolonged into
superior (cornu superius) and inferior horns (cornu inferius),
the superior giving attachment to the thyrohyoid ligament, the
inferior articulating with the sides of the cricoid cartilage.

The cricoid cartilage [cartilago cricoidea) resembles a seal
ring, narrow in front, or anterior portion {arcus cartilaginis
cricoidea), the back part of the upper border articulates with
the arytenoid cartilage, and on each side externally are two
facets for the articulation of the inferior horns of the thyroid.

The epiglottis {cartilago epiglottica) is a spoon-shaped,
fibrocartilaginous plate, large above, its narrow inferior extrem-
ity is prolonged and attached by a band of fibroelastic tissue of
thyroepiglottic ligament {ligamentum thyreoepiglotticum) to
the thyroid cartilage. It is also attached to the posterior sur-
face of the hyoid bone by the hyoepiglottic ligament {ligamen-
tum hyoepiglotticum). The anterior or lingual surface has
three reflections of mucous membrane between it and the tongue

(254)

VOCAL AND RESPIRATORY APPARATUS. 255

{plica- ^lossoepiglotticce) , called the glossoepiglottidean liga-
ments (ligaiueittum glossoepiglotticum ).

The arytenoid cartilages (cartilagines arytwnoidea) each

resembles the mouth of a pitcher, from which they are named.
They are smaller than the other two, and are situated on the
summit of the cricoid cartilage posteriorly. They are three-
sided, the apex extends backward, and is surmounted by the
supra-arytenoid, cornicula laryngis, or cartilages of Santorini
( cartilagines corniculatce) .

The posterior surface has attached to it the arytenoid mus-
cle. The anterior surface has attached to it the thyroarytenoid
muscle and the false vocal cord. The internal surfaces are
opposed to each other and supplied with mucous membrane. Of
the three angles at the base, the outer gives attachment to the
cricoarytenoid muscle, lateral and posterior. The anterior (pro-
ms vocalis) is prolonged for attachment of the true vocal
cord.

The cuneiform cartilages (cartilagines cuneiformes), or
cartilages of Wrisberg, are two small rod-shaped bodies extend-
ing upward from the arytenoid cartilages into the arytenoepi-
glottidean fold (plica aryepiglottica) .

The cartilages of the larynx, with the exception of the
epiglottis, are composed of true cartilage.

The LIGAMENTS of the LARYNX are divided into two sets —
the extrinsic, those connecting the epiglottis and thyroid car-
tilage with the hyoid bone, and the intrinsic, those which con-
nect" the various cartilages together. The extrinsic consist of
three : —

1. Thyrohyoid membrane [membrana hyothyreoidea) . connecting
the upper border of the thyroid cartilage with the inner surface of the
hyoid bone;

2 and 3. The, two lateral thyrohyoid ligaments (Ugamewtvm hyo-
thyreoideum laterale), ftbroelastic cords connecting the superior horns
the thyroid cartilage with the extremities of the great horns of the
hyoid bone. They contain a small aodule, bhe cartilago triticea.

The intrinsic ligaments are sixteen iii number, as follows: —

Hyoepiglottic ligament ;
Cricothyroid membrane;
Two cricothyroid capsular ligaments;
Two cricoarytenoid Ligaments;
Two cricoarytenoid capsular ligaments;
Two superior thyroarytenoid ligaments (in false cords);
o inferior thyroarytenoid ligaments (in true cords);
Thyroepiglotl i<- ligamenl ;
Three gloMoepiglottic folds.

256

HUMAN ANATOMY.

The hyoepiglottic ligament (ligamentum hyoepiglatticum)
is a fibre-elastic band, connecting the anterior surface of the
epiglottis with the upper border of the hyoid bone. The liga-
ments connecting the cricoid to the thyroid cartilage are three
also — the cricothyroid ligament, capsular ligaments and syno-
vial membranes.

The cricothyroid membrane (conus elasticus), a yellow,
elastic band, connects the adjacent margins of the cricoid and
thyroid cartilages, and extends from the upper border of the
cricoid cartilage to the lower margin of the true vocal cords.

Fig. 94.

Vertical section of larynx: 1, body of hyoid bone; 2, epiglottis;
3, thyrohyoid membrane; 4, great cornu of hyoid; 5, false vocal cord;
6, thyrohyoid ligament; 7, ventricle of larynx; 8, thyrohyoid mem-
brane; 9, true vocal cord; 10, arytenoepiglottidean fold; 11, thyroid
cartilage; 12, superior cornu of thyroid; 14, arytenoid muscle; 16,
arytenoid cartilage; 18, cricoid cartilage.

The two cricothyroid capsular ligaments (articulatio crico-
tliyreoidea) surround the articulations between the inferior
horns of the thyroid and the cricoid cartilage.

The synovial membrane (capsida articularis cricothyre-
oidea) lines the capsular ligaments, forming a true enarthrodial
joint.

The ligaments of the epiglottis are the thyroepiglottic
{ligamentum thyreoepiglotticum) , the hyoepiglottic (ligamen-
tum, hyoepiglotticum) , and the three glossoepiglottic folds
(plicce glossoepiglotticce) of mucous membrane before described.

VOCAL AND RESPIRATORY APPARATUS. 257

The superior aperture (ad Hits laryngis) of the larynx is a
triangular opening with the apex in front. It is hounded behind
by the apices of the arytenoid cartilages and corniculse laryngis,
in front by the epiglottis, and laterally by the arytenoepiglot-
tidean folds. From this, as its superior boundary, the cavity of
the larynx extends as low as to the lower border of the cricoid
cartilage. The true vocal cords and the thyroarytenoid muscle
divide It into two parts, the narrow fissure between the two cords
being called the chink of the glottis (rima glottidis).

The superior or false vocal cords (jdiar ventricular es) arc
two folds of mucous memhrane inclosing the superior thyro-
arytenoid Ligaments (ligamenium ventricular e) .

The inferior or true vocal cords (plica vocalis) are two
folds of mucous memhrane inclosing the inferior thyroarytenoid
Ligaments, composed of elastic tissue, from the sides of the upper
border of the cricoid cartilage, extending upward to the hases of
the arytenoid cartilages, and lower portion of the angle of the
thyroid. Their upper margins correspond to the lower edges of
the ventricles of the Larynx.

The ventricle of the larynx (vcntriculus laryngis [Mor-
gagnii]) is a deep fossa on either side of the larynx, bounded
above by the false vocal cords, below by the inferior or true
■ I cords, and externally by the thyroarytenoidens muscle.
The sacculus laryngis (appendix ventriculi), or laryngeal
pouch, is a membranous sac lined with mucous memhrane, open-
ing into the anterior portion of the ventricle of the larynx. Its
inner or laryngeal surface is covered by the arytenoepiglot-
tideus inferior (compressor sacculi laryngis [Hilton]), and the
outer side by the thyroepiglottideus and thyroarytenoideus mus-
cles. It is compressed by these muscles, discharging its mucous
secretion upon the true vocal cords.

MusciJES. — The intrinsic muscles of the larynx consist of
two sets, live connected with the vocal cords and rima glottidis,
an. I tlncc with the epiglottis. The five muscles of the vocal
cords are: —

| ricothyroid (m. cricothyreoideus) . — Origin, from the
front and Bides of the cricoid cartilage; insertion, into anterior
border of the inferior cornua, and lower margin of the thyroid
cartilage; action, elongates and renders tense the vocal cords;
nerve, superior Laryngeal.

i ricoarytcmotdeus Posticus (m. cricoarytcenoidus poste-
rior). -Origin, from the sides and posterior surface of the

cricoid cartilage; Insertion, into the outer angle of the base of
arytenoid cartilage; action, rotate- the arytenoid cartilages out-

17

258 HUMAN ANATOMY.

ward, opening the glottis, and rendering tense the vocal cords;
nerve, recurrent laryngeal.

Cricoarytcenoideus Lateralis (m. cricoarytcenoideus later-
alis).— Origin, from npper and outer side of the cricoid carti-
lage; insertion, in front of the preceding into the outer angle of
the base arytenoid; action, rotates the arytenoids inward, clos-
ing the glottis; nerve, recurrent laryngeal.

Arytcenoideus. — Origin,, from outer border and posterior
surface of one arytenoid cartilage; insertion, into the same part
of the other — its fibers are oblique (m. arytcenoideus obliquus),
and transverse (m. arytamoideus transversus) ; action, by ap-
proximating the arytenoids closes the back part of the glottis;
nerves, superior and recurrent laryngeal.

Thyroarytamoideus (to. tliyroarytanoideus) . — Origin, from
the cricothyroid membrane and lower half of the entering angle
of the thyroid cartilage; insertion, into anterior surface and
base of the arytenoid cartilage — it consists of inferior (to.
vocalis) and superior portions, the former entering into the
formation of the true vocal cords; action, mainly relaxes the
true vocal cords by drawing the arytenoids forward; nerve,
recurrent laryngeal.

The muscles of the epiglottis are : —

Thyroepiglottideus (to. tliyreoepiglotticus) . — Origin, from
the inner surface of thyroid cartilage; insertion, into the mar-
gin of epiglottis an^L arytenoepiglottidean fold; action, com-
press the sacculus laryngis and depress the epiglottis; nerve,
recurrent laryngeal.

Arytcmoepiglottideus Superior. — Origin, from apex of
arytenoid; insertion, into arytenoepiglotticlean folds; action,
constricts the superior laryngeal aperture; nerve, recurrent
laryngeal.

Aryto3noepiglottideus Inferior, or Compressor Sacculi
Laryngis of Hilton. — Origin, from middle of internal portion
of the arytenoid; insertion, into upper and inner part of epi-
glottis; action, compresses the sacculus laryngis; nerve, recur-
rent laryngeal.

The lining mucous membrane of the larynx is continuous
with that of the pharynx and trachea. It forms the glosso-
epiglottic and arytenoepiglottic folds, adheres tightly to the
epiglottis, vocal cords and the interior of the cricoid cartilage,
but is more loosely attached to other parts. It contains numer-
ous racemose glands, particularly along the posterior margin of
the arytenoepiglottidean fold, and in front of the arytenoid car-
tilages, where they are called the arytenoid glands. Its epithe-

VOCAL AND RESPIRATOR! APPARATUS. 259

Hum is of the ciliated, columnar variety below the true vocal
cords, and above this point in front as high as the middle of
the epiglottis. The other portions are covered by squamous
epithelium.

The arteries are the laryngeal branches from the superior
and inferior thyroid, and the cricothyroid branches of the supe-
rior thyroid.

The veins join the inferior, middle and superior thyroid
veins.

The lymphatics enter the deep cervical -lands.

The nerves are the inferior or recurrent laryngeal, the
superior laryngeal branches of the pneumogastric and branches
from the sympathetic nerve.

The superior laryngeal supplies sensation to the larynx. It
descends from the inferior ganglion of the pneumogastric, lie-
hind the'internal carotid at the side of the pharynx, and divides
into two branches — the internal laryngeal pierces the thyrohyoid
membrane to supply the mucous membrane and arytenoid mus-
cle the external laryngeal supplies the cricothyroid muscle.

The inferior or recurrent laryngeal, from its origin, winds
around the subclavian on the right side and around the arch of
the aorta on the left side, and ascends by the side of the trachea
to the larynx, of which it is the motor nerve, supplying all the
muscles of the larynx except the cricothyroid, giving off in its
course cardiac, esophageal, tracheal and pharyngeal branches,
and anastomosing with the superior laryngeal nerve.

TRACHEA AM) BRONCHI.

The trachea, or windpipe, is a membranocartilaginous tube,

about four and a half inches in length, three-quarters to one
inch in width, extending from the fifth -cervical to the upper
border of the lil'th dorsal vertebra. It divides into two bronchi
(hi fun alio trachea), the right (bronchus dexter), about an inch
long and nearly at right angles, passing behind the right pulmo-
nary artery on a level with the lil'th dorsal vertebra; the left
[bronchus sinister), narrower, about twice as long, passes
beneath the arch of the aorta on a. level with the fifth or Bixth
dorsal vertebra, behind the lefl pulmonary artery. The trachea.
ami bronchi are formed of a series of cartilaginous rings, incom-
,it their posterior third, connected by fibroelastic mem-
brane, and lined by columnar ciliated epithelium. The last ring
is triangular, go ;i- to tit the rings of the two bronchi. The
mucous membrane contains numerous racemose glands, the

260 HUMAN ANATOMY.

largest on the posterior surface, called the tracheal glands
(glandulce tracheales). The muscular fibers consist of two
layers^ longitudinal, the most external, and transverse, internal,
both unstriated.

Relations. — The trachea has the following relations in the
neck : —

Laterally.

Lobes of the thyroid body;
Carotid arteries;
Inferior thyroid arteries.

Anteriorly.

Skin, superficial and deep fascia;

Anterior jugular veins;

Left innominate vein;

Inferior thyroid plexus of veins;

Isthmus of thyroid body;

Arteria thyroidea ima (sometimes).

Posteriorly.
Esophagus ;
Vertebral column;
Recurrent and inferior laryngeal nerves.

5

The following in the thorax : —

Laterally.
Pleura;
Pneumogastric nerves.

Anteriorly.
Sternum ;

Remains of thymus;
Arch of aorta;

Right and left innominate veins;
Left carotid artery;
Deep cardiac plexus.

Posteriorly.
Esophagus.

The arteries are derived from the inferior thyroid and
bronchial.

The veins empty into the thyroid and bronchial plexuses.

The nerves are from the pneumogastric and sympathetic.

The lymphatics empty into the mediastinal glands.

The bronchi are the continuation of the trachea from its
bifurcation to the hilus of the lung.

VOCAL AM) RESPIRATORY APPARATUS. gul

Eight bronchus (bronchus dexter) is shorter, about one
inch in length, placed more horizontally, and wider. It divides
at the hilus into three short branches, corresponding to the divi-
sions of the right lung.

Left bronchus {bronchus sinister) is longer, nearly two
inches in length, placed more obliquely, and narrower than the
right. It divides into two long branches corresponding to the
number of lobes.

The two bronchi subdivide into the bronchial tubes, or
bronchioles, which ramify throughout the lungs, dividing and
subdividing (bronchioli respiratorii) , to end finally in the pri-
mary lobules, where they communicate with the intercellular
air-passages. Their cartilages consist of thin plates, distributed
irregularly along the tubes, and in the finer tubes disappearing
entirely. The mucous membrane of the bronchi and bronchial
tubes is lined throughout with columnar ciliated epithelium.

The arteries, veins, nerves and lymphatics are the same as
for the trachea.

THE LUNGS.

The lungs (pulmones), the organs of respiration, are two in
number, occupying the lateral cavities of the chest, separated
from each other by the heart and structures within the medias-
tinum. They accurately fill the cavity of the chest at all times,
and are covered by the pleura. They are conical in shape, pre-
senting each a base, apex, two borders, and two surfaces. The
apex {apex pulmonis) extends upward above the level of the
first rib; the base (basis pulmonis) occupies the convex surface
of the diaphragm; the external, or thoracic surface (fades cos-
talis), is accurately applied to the wall of the thorax; the inner
surface (fades mediastinalis) is in contact with the pericar-
dium, and is marked by a depression, the hilum pulmonis (hilus
pulmonalis) , at the root of the lungs. The posterior border
rests on either side of the spinal column, and the anterior border
is thin and overlaps the pericardium.

The root (radix pulmonalis) of each lung, situated near its
middle, is composed of the following structures, surrounded by
;i reflect ion of pleura : —

Bronchus ;

Pulmonary artery -,

Pulmonary rains;

Bronchia I glands ;

Bronchial vessels;

Posterior and anterior pulmonary plexuses of nerves;

I onnective I issue.

2(52 HUMAN ANATOMY,

The root of the right lung is behind the right superior
cava and the vena azygos arches over it. The root of the left
lung lies below and in front of the arch and descending aorta.
The relative positions of the pulmonary veins, pulmonary artery
and bronchus on either side are : —

Both sides, from before backward — -

V. Pulmonary veins,

A. Pulmonary artery,

B. Bronchus.

Right side, from above downward —

B. Bronchus,

A. Pulmonary artery,

V. Pulmonary veins.

Left side, from above downward —

A. Pulmonary artery,

B. Bronchus,

V. Pulmonary veins.

The weight of the lungs varies according to many condi-
tions. In the adult the approximate weight is about forty-two
ounces, the right being two ounces heavier than the left, and
their total capacity about three hundred cubic inches. The
right lung has three lobes, the left but two, of which the lower
is the larger. The lungs in infancy are of a pale rose color, but
later become of a leaden hue, variegated with dark slate and
bluish black. They are highly elastic, crackle on pressure, and
float in water, having a specific gravity of 0.345 to 0.746. In
the fetus before birth, and also in certain diseases, they sink in
water. The structure of the lung consists of an external serous
coat, the visceral layer1 of the pleura, a subserous areolar tissue,
highly elastic, and the parenchyma, or proper substance of the
lungs. The latter is made up of small polyhedral primary
lobules, which unite to form secondary lobules, the latter giving
rise to the markings on the surface. Both the primary and
secondary lobules are held together by connective tissue. A
primary, lobule represents the structure of the entire organ, con-
sisting of a bronchiole (bronchioli) and infundibula, or air-
passage, communicating with numerous air-cells.

The air-cells (infundibula) are minute polyhedral cavities,
from one-two-hundredths to one-seventieth of an inch in diam-
eter, separated from each other by a thin lamina, and communi-
cating freely with the infundibula. They vary much in size,
being largest on the surface at the thin borders and at the apices.

VOCAL AND RESPIRATORY APPARATUS.

263

Bach air-cell is composed of the basemenl membrane, lined with
squamous epithelium, and surrounded by a minute capillary
network of blood vessels, which intervene between the terminal
branches of the pulmonary artery and the commencement of the
pulmonary veins. Between the cells the capillary network forms
a single layer.

The pulmonary artery conveys the venous blood 1" the
lungs and terminates in the capillary network about the air-
cells, from which proceeds the pulmonary vein, which passes

Fio. 95.

Heart and lungs: i, right ventricle; '■'., right auricle; 5, pulmo-
nary artery; 9, aorta; 10, Buperior cava; 20, root, of lung; 21, 22, 23,
upper, middle and lower lobes of right lung; 24, 'J.',, upper and lower
lobes of l<ft lung.

along the bronchial tubes to the lefl auricle of the heart. The
bronchial arteries Bupply the structure of the lungs. They are
<Iiti'v<-<I from the aorta, and follow the course of the bronchial
tubes, tin- bronchial veins returning the blood to terminate in
the hemiazygos <<v superior intercostal rein on the left.

The lymphatics are numerous and consist of a superficial
set converging to the root and a deep sei along the course of
t!i<' tubes, and both enter the bronchial glands.

The nerves are derived from the anterior and posterior pul-
monary plexuses of the pneumogastric and sympathetic, the hit-
ter the larger. Ganglia are found upon these nervi

264 HUMAN ANATOMY.

THE PLEURAE.

Each lung is invested by a delicate serous membrane, the
pleura, which lines the internal wall of the thorax and is
reflected at the root of the lung over that organ. It consists
essentially of two layers, a parietal {pleura parietalis), or pleura
costalis, and visceral (pleura pulmonalis) . It adheres accu-
rately to the subjacent structures, and is called, from its position,
costal (pleura costalis), diaphragmatic (pleura diaphragmatica) ,
mediastinal (pleura mediastinalis) , and pulmonary. The space
between the two layers of each pleura, known as the cavity of
the pleura (cavum pleurce), contains a thin, serous secretion.

A fold extending downward from the root of the lung to
the diaphragm forms the so-called pulmonary ligament, or liga-
mentum latum pulmonis.

Each pleura is a closed sac ; the right is wider, shorter and
extends higher in the neck than the left. They do n'ot meet in
the median line, except opposite the upper part of the gladiolus,
but have a space between them known as the mediastinum.

The arteries are from the intercostal, bronchial, pericardiac,
internal mammary, musculophrenic and thymic. ml

The veins accompany the arteries.

The lymphatics are numerous, and empty into the inter-
costal and posterior mediastinal glands.

The nerves are from the phrenic and sympathetic.

MEDIASTINUM.

The mediastinum is the space left between the two pleura
in the median line b^tweejijthe sternum_and^vertebral column,
and "contains the heart _ within its pericardium and all the
thoracic viscera except the lungs. The intervals in the media-
stinum from their position are named anterior, middle, poste-
rior and superior mediastinal cavities. The boundaries and
contents of the four mediastinal cavities are as follow: —

Anterior mediastinum-, bounded in front by the sternum;
:' laterally, pleura; behind, the pericardium. It contains: —

Triangularis sterni muscle; S

Remains of thymus gland; w

Left internal mammary artery and vense comites; v^

Lymphatic vessels from convex surface of the liver ;V

Areolar connective tissue. «**"

Middlemediastinum, bounded in front by the anterior
mediastinum ; laterally, by the pleura ; behind, posterior media-
stinum. It contains: —

VOCAL AND RESPIRATORY APPARATUS.

265

Ascending portion of aorta; ■""

Superior vena cava ; •"

Heart, inclosed in the pericardium ; •**"

Bifurcation of trachea ; ^-^

Pulmonary artery and vein-;; •"-"

Phrenic nerves; -"-"*

Arterise comites nervi phrenici, from the internal mammary. "

Posterior mediastinum, bounded in front by the pericar-
dium and root of the lungs; behind, vertebral column; laterally
pleura. It contains: —

Esophagus; •—""■
Thoracic duct; "
Descending aorta ;
Lymphatic glands and vessels;

iVena azygos major; *--
Vena azygos minor; «-"*
Superior intercostal veins ;
I'lieiimun-iistric nerves; —

Great splanchnic nerves, x"

The sujierior mediastinum is that portion of the mediasti-
nal space above the upper l)order of the fifth thoracic vertebra.
Tt is hounded in front by the manubrium stern i; behind, by the
upper dorsal vertebra; laterally, by the pleura. It contains : —

Origin of sternothyroid muscle; ^
Origin of sternohyoid muscle; ^
Lower end of the longus colli

muscle; ^
Innominate artery; S
Left carotid artery; "^
Subclavian artery; ^
Transverse portion of the aorta ;-^
Innominate veins; ^-
Superior vena cava; ,/

Left superior intercostal vein; /"

Left recurrent laryngeal nerves;

Cardiac nerves; -"

Pneumogastric nerves; "

Phrenic nerves ; ^

Esophagus ;

Trachea; -**

Thoracic duct;

Remains of the thymus gland; "

Lymphatics. s

THE GENITOURINARY APPARATUS.

The genitourinary apparatus consists of the urinary organs
and the male and female generative organs.

THE URINARY ORGANS.

The urinary organs consist of the kidneys, ureters, bladder
and urethra.

The kidneys (renes) are two glandular organs, situated
deeply in the lumbar region, opposite the second or third lum-
bar vertebra and last dorsal, the right a little lower than the
left. They are surrounded by fat (capsula adiposa) and held
in position by the blood vessels and loose connective tissue. The
right kidney is in relation in front with the liver, descending
portion of the duodenum and ascending colon. The left is in
relation with cardiac end of stomach, lower end of spleen, tail
of pancreas and descending colon. Each kidney measures about
four inches in length, two in width, and one in thickness and
weighs from four and one-half to six ounces in male, four to
five and one-half in female. Their shape is characteristic. The
notch at the inner side is called the hilus (hilus renalis), and
communicates with the interior cavity, the sinus, at which the
blood vessels, nerves, and ureter have their passage: The kid-
neys have a special fibrous coat designated as the true capsule
(tunica fibrosa), slightly adherent, which extends into the hilus
and becomes continuous with the fibrous coat of the blood vessels
and ureters. The relative position of the arteries, veins, and
ureter at the hilus are, from above downward: —

A. Artery,
V. Vein,

U. Ureter; "

from before backward : —

V. Vein,
A. Artery,
U. Ureter.

The general structure of the kidney consists of a cortical
substance (substantia corticalis) and a medullary substance
(substantia medullaris), the latter arranged into conical masses

(266)

THE GENITOURINARY APPARATUS.

267

called renal pyramids, with their bases in the cortical substance.
and their apices, the renal papillae {papillae renales), projecting
into the calices (calyces renales) of the pelvis within the sinus
of the kidney (sinus renalis). The renal pyramids of Malpighi
(pyramides renales), about ten to fifteen in number, correspond-

Fig. 96.

Longitudinal section of kidney: 1, cortex: 2, medulla: 3, section
of tubulee in boundary layer; 4, fat of renal sinus; 5, renal arteriole;
A, branch of renal artery; 0, renal calyx; U, ureter.

ing to the fetal lobules, are arranged into three irregular rows.

mbstance, or parenchyma of the kidney, is composed of
uriniferoue tubulee (tvhuli renale), held together by compara-
tively little connective tissue. The terminal orifices of these,
several hundred to each papilla, open on its summit.

Course of the Tubuli Uriniferi. — Beginning at the Mal-
pighian capsule (capsvla glomeruli) within the cortex, cadi

268 HUMAN ANATOMY.

tubule pursues a very tortuous and complicated course before it
terminates in the renal papilla (papillae renales), the outline of
which is as follows (after Gray) : — ■

(a) Neck — the constricted portion below the capsule, before it ter-
minates in the renal papillae,

( b ) Proximal convoluted tube, \ Within the cortical struc-

(c) Spiral tubule of Schachowa, J ture.

(d) Descending limb of Henle's loop, \ Within the medullary

(e) Henle's loop, j structure.

... . ,. ,. , j. tt , , , f Partly in medullary and

(f) Ascendmg limb of Henle s loop, j 'partly in cortical.

(g) Irregular tubule, |

(h) Distal convoluted tubule, > Cortical structure.

(d) Curved tubule, J

(j) Straight collecting tubule — descends through the medullary
structure to open by an orifice in a renal papilla.

The straight, collecting or receiving tubes converge as they
descend, and unite and reunite until there are about one dozen,
but they vary from eight to twenty, one opening on the summit
of each papilla. In the cortical portion they form groups, or
medullary rays, giving the appearance of conical masses in the
cortical substance with their apices toward the periphery — the
so-called pyramids of Ferrein. The tubules are composed of a
basement membrane, lined with pavement epithelium. In the
neck the epithelium becomes continuous with that of the Mal-
pighian capsule, and at the glomerule the wall is reflected upon
the inclosed tuft, or Malpighian corpuscle. In other situations
the epithelium varies much in shape and size. The renal arter-
ies subdivide at the hilus, cross the sinus, and enter the renal
substance between the renal papillae. They terminate in the
renal glomerules, or Malpighian corpuscles. Each one of these
remarkable convolutions of capillaries is about one one-hun-
dredth of an inch in diameter and inclosed in a pouch-like
dilatation of the uriniferous tubules or Malpighian capsule, or
capsule of Bowman. The efferent vessels form, together with
others, a capillary network between and around the uriniferous
tubules. They are made up of three sets: (a) the plexuses
around the tubuli contorti; (&) the veins beneath the capsule;
and (c) the plexuses about the apices of the pyramids of Mal-
pighi. These form the vence interlobular 'es, which join the vence
rectce, and together form the renal veins, vence propria? renales.
Those in the sinus unite together to form the renal vein, and
open into the inferior vena cava, the left crossing in front of
the abdominal aorta.

THE GENITOURINARY APPARATUS.

269

T and 8. Ascending
limb of lleule B
loop tuba.

Subcapsular layer with-
out Mai pigbian cor-
puscles.

12. First part of col-
lecting tube.

11. Distal convoluted
tubule.

A/ A. Cortex.

10. Irregular tubule.

3. Proximal convo-
luted tubule.

9. Wavy part of as-
cending limb.

2. Constriction or

neck.

4. Spiral tubule.

1. Malpighian tuft
surrounded by

Bowman's capsule.

8. Spiral part of as-
cending limb of
Uenle's loop.

B. Boundary Zone.
6. Descending limb of
Uenle's loop tube.

15. Tubule of Bellini. 15

8. Honle s loop.

■ C. Papillary Zoijk.

Diagram of urinlferous tubules: i. Malpighian capsule; 2, proxi-
mal convoluted tubule; 2 b, distal convoluted tubule; '■'•. descending
limii of Henle's loop; i, ascending limb of Uenle's loop; 5, irregular
tubule; 6, collecting tube; a, apex of pyramid; 6, base of pyramid;
C, cortical portion.

270 HUMAN ANATOMY.

The ureter commences as a compressed pouch, the pelvis.
Within the sinus the pelvis divides, and subdivides into several
small funnels, or calices\, each one of which receives one or two
projecting renal papilla?. The calices, pelvis and ureter are all
of the same structure, consisting of a fibrous and unstriated
muscular and a mucous coat. The fibrous coat (tunica adven-
titia) becomes continuous with the capsule above and below in
the fibrous structure of the bladder. The muscular coat (tunica
muscularis) ceases at the base of the renal papillae, but the
mucous membrane becomes continuous with that of the urinif-
erous tubules. Its epithelium is of the transitional variety,
consisting of several layers of cells of varying shapes, resting
upon a basement membrane.

The nerves are derived from the renal plexus of the sym-
pathetic, formed by branches in the semilunar ganglion, the
solar plexus and the lesser and smallest splanchnic nerve.

The lymphatics communicate with the lumbar glands.

The ureter proper is a musculomembranous tube, sixteen
to eighteen inches in length, about the diameter of a goose quill,
extending from its origin in the pelvis of the kidney to the
basal or posterior angle of the vesical trigone, which it enters
by passing obliquely through the muscular and mucous walls of
the bladder.

Course- — It descends upon the psoas magnus muscle, be-
neath the peritoneum, being crossed by the spermatic vessels.
About the first division of the sacrum it crosses the external or
common iliac artery, passing behind the sigmoid flexure on the
left and the ileum on the right side, to enter the pelvis, where
it reaches the bladder within its posterior false ligament.

In the male it passes behind the vas deferens.

In the female it crosses the uterine artery one-third to one-
half inch from the cervix uteri and passes along the side and
upper part of the vagina to the bladder (vide Vagina).

Muscles of the Ureters. — Two oblique muscles. Origin.
behind the orifices of the ureters ; insertion, into the middle lobe
of the prostate gland; action, they guard the orifices of the
ureters, and prevent the reflux of urine.

Suprarenal capsules (vide Ductless Glands).

THE BLADDER.

The bladder (vesica urinaria) is a musculomembranous sac,
the reservoir for the urine, situated in the anterior part of the
pelvis, behind the pubes, in front of the uterus and vagina in
the female, and the rectum in the male.

THE GENITOURINARY APPARATUS. •>] \

It measures, moderately distended, five inches in length,
three in width, and holds about one pint. It consists of a body,
summit. base and neck.

The body {corpus vesica) is partially invested with peri-
toneum behind, but in front it is wanting, the body heing in
relation with the symphysis pubis, triangular ligament, and
internal obturator muscles.

The summit, or apex (vertex vesicce), is rounded, and
directed upward and forward, being connected to the umbilicus
by the urachus, the remains of the fetal allantois, and also by
the obliterated hypogastric arteries, one on either side.

The space hounded by the pubic surface and the sides of
the bladder uncovered by peritoneum, filled by the rectovesical
fascia, is known as the space of Eetzius.

The base, or fundus (fundus vesicae), in the male is sit-
uated upon a triangular space upon the second portion of the
rectum, it- base formed behind by the rectovesical fold, its apex
by the prostate gland, and its sides by the vas deferens and
vesiculae scminales.

In the female it is situated in contact with the cervix uteri
and anterior wail of the vagina, adhering closely to the latter.
It- upper portion has a peritoneal covering.

The neck, or cervix (collum vesicce), is the contracted por-
tion, coin unions with the urethra. It is encircled in the male
by the prostate gland, and is directed obliquely when the in-
dividual is in the erect posture.

The ligaments of the bladder consist of five true ligaments
derived from the pelvic fascia and the urachus; and five false
ligaments derived from the peritoneum.

The true ligaments are: —

Two anterior (puboprostatic) (ligamenta puboprostatica) ,
two folds of rectovesical fascia passing from the pubic symphy-
sie to the- cervix and upper surface of prostate gland;

Two lateral folds of rectovesical fascia connecting the lat-
eral surfaces of prostate gland with sides of base of bladder;

The urachus {ligamentum umbilicale medium), an obliter-
ated fetal structure, passing as a fibromuscular cord from the
apei of tin; bladder to the umbilicus.

The false ligaments are: —

Two posterior ligaments (plicce rectovesicales) are peri-
tonea] fold.- parsing between ^ides of rectum in male, sides of
uterus in female, to posterolateral surface of bladder, inclosing
obliterated hypogastric arteries, ureters, vessels and nerves;

272 HUMAN ANATOMY.

Two laterals (Ugamenta umbilicale laterales) are folds of
peritoneum passing from iliac fossge to sides of bladder;

The superior (plica umbilicalis media) is a single peri-
toneal fold inclosing the obliterated hypogastric arteries from
apex of bladder to umbilicus.

The structure consists of four coats, a serous, muscular,
submucous and mucous.

The serous coat (tunica serosa) is derived from the perito-
neum. It covers the posterior surface from the ureters to the
summit, and is reflected from the sides to the walls of the pelvis
and abdomen.

The muscular coat (tunica muscularis) is made up of
unstriated fibers arranged in three layers: —

(a) Longitudinal external layer (stratum externum),
named the detrusor urines muscle;

(b) Circular middle layer (stratum medium), forming at
the neck the sphincter vesicae;

(c) Longitudinal internal layer (stratum internum).
The submucous or cellular coat (tela submucosa) , made up

of fibrous and elastic tissue, supports the mucous coat and unites
it with the muscular.

. The mucous membrane (tunica mucosa) is smooth and of
a pale rose color. Its epithelium is continuous with that of the
ureters and pelvis of kidneys; its superficial layer, large, tessel-
lated, polyhedral cells ; its deep layer of club-shaped and spindle-
shaped cells.

The inner surface of the base presents a triangular space,
the vesical trigone, or trigonum vesica, apex in front, formed
by the orifice of the urethra, its basal angles behind about two
inches apart, and each about one and one-half inches behind the
urethral orifice, formed by the orifices of the ureters: —

U

u u

2"

The uvula vesica is an elevation of mucous membrane pro-
jecting from the floor near the apex of the trigone into the
orifice of the urethra.

The arteries are the superior, middle and inferior vesical,
with branches from the obturator and sciatic in the male, and
branches from the vaginal and uterine in the female.

The veins from the vesicoprostatic empty into the internal
iliac vein.

THE GENITOURINARY APPARATUS. 273

Lymphatics follow the course of the vessels and enter the
lumbar glands.

The nerves to the base and neck are from the third and
fourth sacral, and to the summit, from the hypogastric plexus

of the sympathetic.

GENERATIVE APPARATUS.

Male Organs.

The male organs of generation consist of the testes, vasa
deferentia. vesiculae seminales and penis.

The testicles (testes) are two glandular bodies which
secrete the spermatic fluid, and are suspended by the spermatic
cords within the scrotum, the left a little larger and lower than
the right. They are oval, compressed laterally, measure one and
a half to two inches in length, one inch in breadth, one and
one-fourth inches in their anteroposterior diameter, and weigh
from six to eight drachms.

They each consist of a body, or testicle proper, and an
epididymis. The latter consists of a head or globus major
{caput apididymidis) , body or central portion (corpus epidid-
ymides) and tail or globus minor (cauda epididymidis) .

The scrotum consists of the skin marked in the median line
by the raphe (raphe scroti), formed by the union of the genital
folds, and the dartos, a reddish, contractile tissue which sur-
rounds the testes and extends from the raphe to the under sur-
face of the penis, forming the septum scroti, which divides it
into two cavities for the testes.

The spermatic cord (funiculus spermaticus) is made up of
the following structures: —

Externa] spermatic, or intercolumnar fascia;

Cremaster muscle;

Internal spermatic fascia, or fascia propria;

Yas deferens;

Spermal ic artery •.

Deferentia] artery from superior vesicle;

Cremasteric artery, from epigastric;

Vasa Bpermatica;

Lymphatic vessels;

Spermatic plexus of nerves [from renal and aortic plexuses];

Genital branch of genitocrural;

Scrotal branch of the ilioinguinal,

Tt commences al the internal abdominal ring, passes ob-
liquely through the inguinal canal, emerges at the external
abdominal ring, descends into the Bcrotum, and terminates at
the posterior border of the testes.

18

274 HUMAN ANATOMY.

The external spermatic or intercolirmnar fascia is derived
from the aponeurosis of the external oblique muscle. This mus-
cle arises within the inguinal canal from Poupart's ligament
and pubic spine, and descends along the cord in loops. Its
fibers are striated.

The cremaster muscle, or cremasteric fascia {fascia cremas-
terica) or middle spermatic fascia, is derived from the lower
border of the internal oblique and transversalis muscle.

The internal spermatic fascia, or fascia propria, is the
infundibuliform process of the transversalis fascia.

The proper coverings or tunics of the testicle are three —
tunica vaginalis, tunica albuginea and tunica vasculosa : —

The tunica vaginalis (tunica vaginalis propria testis) is a
serous membrane surrounding the testes, and at the posterior
portion is reflected on itself to form a sac. The outer portion
of the latter is loosely attached, except at the lower part of the
testicle, where the gubernaculum testis binds it down.

The tunica albuginea is a dense, white fibrous structure,
continuous at the upper part with a similar structure on the
epididymis. At the back part it projects into the glandular
substance of the testicle to form the mediastinum testis (corpus
Tliglimori) , from which numerous imperfect septa, called
trabecule (septula testis) diverge, and with similar cords from
the tunica albuginea serve to maintain the shape of the gland
and divide it into lobules.

The tunica vasculosa (pia mater testis) lies within the
tunica albuginea, and is the source and termination of the
blood-vessels to the secretory substance of the gland, resembling
the pia mater of the brain.

The glandular structure of the testis is divided into several
hundred (two hundred and fifty to four hundred) pyramidal
lobules (lobuli testis), each one of which consists of from one
to three tubuli seminiferi contorti.

At the conical extremity of the lobules the tubules end in
straight tubes, vasa recta, which enter the mediastinum to form
the plexus retiformis. From the upper part of this the vessels
unite into from twelve to twenty vasa efferentia, which pass out
of the testicle to the epididymis. Within the epididymis these
efferent canals form a series of spermatic cones, the coni vas-
culosi. These end in a coarse, convoluted tube, about twenty
feet in length, forming the body and tail of the epididymis, and
ending in the spermatic duct, or vas deferens (ductus deferens).
These tubes are lined with columnar ciliated epithelium.

THE GENITOURINARY APPARATUS.

275

Fig. 98.

on through bladder, urethra, and testicle: A, urethral
orlfict /•' seminal vesicle; O, colliculus seminalis or verumontanum;
I), prostatic utricle; /.', orifice of ejaculatory duet; F, suspensory
ligament; ff, Cowper's gland; //. bulb of corpus spongiosum; /,
corpus spongiosum; ./, urethra; K, seminal plexus; /-. testicle; l/,
peritoneal fold; V space oi Retzius; O, corpus cavernosum; P, glans
penis; (), prepuce.

276 HUMAN ANATOMY.

The vas aberrans of Haller is a spermatic cone joining the
epididymis, but unconnected with the testicle.

The hydatids of Morgagni are one or two pedunculated
bodies attached to upper part of testis or head of epididymis,
and supposed to be the remains of Muller's duct.

Structure of the Tubules. — The tubuli seminiferi are mi-
nute convoluted tubules, closed at one extremity, consisting of a
hyaline membrana propria lined with several layers of epithelial
polyhedral cells, the seminal cells, from which the seminal or
spermatic fluid is directly elaborated.

These cells undergo a process of indirect division (Icaryo-
hinesis) to form the spermatoblasts, which are arranged into
bundles, and are converted into spermatozoids, the nuclei becom-
ing the head, and the tail, or ciliary appendages, being after-
ward developed. These cells are constantly cast off and replaced.

Descent of the Testes. — In early fetal life the testes are
placed at the back part of the abdomen, below and in front of
the kidneys, and behind the peritoneum.

About the third month a peculiar structure, the gubernacu-
lum testis, appears, attached to the lower end of the epididymis,
and extending as a cord to the bottom of the scrotum. It is
supposed to cause the descent of the testicle. It reaches its full
development between the fifth and sixth month, at which time
the testicle reaches the iliac fossa. It enters the internal abdom-
inal ring by seventh month, and the scrotum by the eighth
month, carrying before it a fold of peritoneum, which is after-
ward shut off, forming the tunica vaginalis testis. Other cover-
ings of the testicles are also derived in this manner. In the
female a structure similar to the gubernaculum forms the round
ligament.

The vas deferens has three coats — (1) an external fibrous
coat {tunica adventitia), (2) an unstriated muscular coat
(tunica muscularis), and (3) a lining membrane (tunica mu-
cosa) of columnar epithelium. It is about one and one-half
feet long and one line in diameter. From the tail of the
epididymis it ascends in the cord, forming an important part,
and lying behind the blood-vessels. It ascends through the
inguinal canal, and at the internal ring descends on the bladder,
crosses the ureter and obliterated hypogastric artery, and runs
forward to form with the duct of the seminal vesicle the ejacu-
latory duct.

The walls of the vas are very thick and the canal very small.
Its course for the most part is straight, but beneath the bladder

THE GENITOURINARY APPARATUS.

277

it becomes enlarged, tortuous, arid more capacious, but again
contracts near its termination.

The arteries of the cord are: —

The spermatic, to the testicle from the aorta:

The vas deferens, or deferent artery, from the superior vesical;

The cremasteric, from the deep epigastric.

CREMRS.TER

MUSCLE.

Fig. 99.

The testicle and epididymis: .4, testis; B, epididymis; 0, tunica
vaginalis; D, vas deferens; /•;, spermatic artery and veins; F, artery
of cord.

The veins from the testis — spermatic reins — unite with
branches from the epididymis to form the pampiniform plexus,
which terminates on the Lefl side passing beneath the sigmoid

re in the left renal vein, on the right side in the inferior

Vlia I

The lymphatics are numerous, and terminate in the lum-
bar elands.

278 HUMAN ANATOMY.

The nerves are from the sympathetic system, and form the
spermatic plexus.

The arteries of the scrotum are derived from the

Cremasteric branch of epigastric;

Superficial external pudic, from the femoral;

Deep external pudic, from the femoral;

Superficial perineal, branch of internal pudic, from internal iliac.

The seminal vesicles (vesiculce seminales) are two mem-
branous pouches, closely adhering to the under surface of the
bladder.

Their size varies, but they usually measure two and one-
half inches in length, one-half inch in breadth, and two to three
lines in thickness.

Each consists of a tube closed at one end, about four to six
inches long, the diameter of a quill, convoluted into a mass. Its
structure is analogous to that of the ducts, but thinner.

The ejaculatory ducts (ductus ejaculatorii) , two in num-
ber, are formed by the union of the vasa deferentia with the
duct of the vesiculge seminales. Each duct is three-fourths to
one inch in length, and passes through the prostate gland to
terminate at the margin of the sinus pocularis by a slit-like
orifice.

The arteries are derived from the inferior vesical and mid-
dle hemorrhoidal. The veins and lymphatics correspond to, and
accompany the arteries, and the nerves are from the hypogastric
plexus of the sympathetic.

The seminal vesicles are not only reservoirs, but secrete a
fluid to dilute the spermatic liquid.

The semen is a viscid, whitish liquid, composed of a color-
less liquid, the liquor seminis, and the spermatozoa and seminal
granules.

The seminal granules are about one-four-thousandth of an
inch in diameter.

The spermatozoa are the essential elements, and consist of
an oval head, a body or middle piece and a tail.

The penis is composed of three columnar bodies, two cor-
pora cavernosa and one corpus spongiosum, invested with skin,
and filled with a peculiar, vascular, sponge-like structure.

It is attached to the pubic arch and symphysis by its root
(radix penis), has a free expanded extremity (glans penis) or
head, and an intermediary portion, the body (corpus penis).

The upper surface is the dorsum, or back. The glans is a
blunt, cone-like body, expanded at its base, the corona, and
attached by its cervix, or neck (collum glandis).

THE GENITOURINARY APPARATUS.

379

The summit has a slit-like aperture, the meatus (orifnum
urethra externum), or orifice of the urethra.

The skin adheres loosely to the organ, and lias a loose, cup-
like fold over the glans, called the prepuce {praspiitmm) , after
which it is reflected into the cervix and glans, becoming con-
tinuous with the mucous membrane of the urethra at the meatus,
to which it is attached below by a hand or bridle, the franum
(frenulum prceputii).

Ttailem Vajl/tab*
Tunic* Afluji a M

Fig. 100.
Vertical section of testicle. (After Gray.)

The ddn covering the glans resembles mucous membrane,
La very rascular and sensitive, hut about the cervix and corona
],;l_ Qumeroufl preputial glands— gUndula Tysom odonfen
(glandndce Tysonii odoriferce), which Becrete the smegma.

The superficial fascia is thin, free from adipose tissue, and
continuous with that of the abdomen and scrotum.

The suspensory Ligamenl (ligamentum suspensorvum perns)
passes from the fronl of the pubic symphysis to the tunica al-
Unnea of the corpora cavernosa. The fundiform ligament, or
li^mentum fundiforme penis, was formerly described as the

280 HUMAN ANATOMY.

suspensory ligament; this is not strictly correct, although the
latter ligament is suspensory in character. The ligamentum
fundiforme penis passes to the penis from the lower part of the
linea alba, and at its penile attachment divides into two por-
tions, between which pass the dorsal vessels and nerves.

The corpora cavernosa (corpora cavernosa penis), or cav-
ernous bodies, constitute more than two-thirds of the bulk of
the organ. They spring as crura from the rami of the ischium
and pubis, swell out into the bulb of the cavernous body, or
corpus cavernosum, join each other in the median line, to ter-
minate in a conical extremity, which receives the glans.

They are grooved above for the dorsal vein, and below for
the corpus spongiosum.

They each have a strong outer fibrous membrane, which,
on uniting, forms a thick partition, complete behind, but incom-
plete and comb-like in front — septum pectvniforme.

From this septum fibroelastic bands diverge in all direc-
tions and form trabecules, which, with the blood-vessels occupy-
ing their intervals, form the erectile tissue of the corpora
cavernosa.

The corpus spongiosum (corpus cavernosum urethrce) com-
mences as. a bulb below the crura and in front of the triangular
ligament. It expands anteriorly into the glans penis, which fits
upon the conical termination of the corpora cavernosa.

The urethra enters above and anteriorly to the bulb (bulbus
urethra), and traverses its entire length to the summit of the
glans, opening at the meatus.

The corpus spongiosum consists of an external fibrous coat,
thinner and more elastic than that of the corpora cavernosa,
and an interior erectile tissue. A thin, muscular layer lines the
external fibrous coat, and another is found beneath the mucous
membrane of the urethra.

The corpora cavernosa get their blood from the arteries of
the corpora cavernosa, and branches from the dorsal artery of
the penis, from the internal pudic.

The corpus spongiosum is supplied by the artery of the bulb.

The arteries of all three bodies terminate finally in the
erectile tissue. Many arterial branches, especially at the root
of the penis, form short convolutions — the helicine arteries
(arteries helicince), which terminate in finer vessels, and sub-
sequently open into the spaces of the erectile tissue. Others
open directly.

THE GENITOURINARY APPARATUS. 281

From these spaces the veins begin; some wind around the
Bide of the organ to the dorsal vein, while others pass under the
pubis to join the prostatic plexus.

The lymphatics are numerous; the superficial join the
inguinal glands, the deep join the lymphatic plexus about the
prostate and other deep lymphatics of the pelvis.

The male urethra (urethra virilis) is the common canal
for the emission of semen and urine, extending from the neck
of the bladder (orificium urethra internum) to the meatus
urinarius (orificium urethral externum). It is from eight to
nine inches in length, and consists of three portions — the pro-
static, membranous and spongy.

The prostatic portion (pars prostatica) extends from the
neck of the bladder to the anterior border (apex) of the prostate
gland. It is one and one-quarter inches in length, and is the
widest and most dilatable part.

Its floor is raised, and presents: —

Yerumonatum, or caput gallinaginis (cotticulus seminalis),
an elevated ridge;

Prostatic sinus (utriculus prostaticus), on each side of the
verumontanum ;

Orifices of the prostatic ducts, in the floor of the prostatic
sinuses;

Sinus pocularis, a depression in the median line in front
of the veruniontanum, presenting the slit-like openings of the
ejaculatory ducts (ductus ejacututorii). This cul-de-sac is one-
quarter of an inch in length. It is homologous with the uterus,
and has received the name of utricle, or uterus masculinus.

The membranous portion (pars membranacea) is about
three-quarters of an inch in length, extending from the apex
of the prostate gland to the corpus spongiosum above and in
advance of the hull). It passes out of the pelvis beneath the
symphysis pubis, traversing the triangular ligament. It is the
least di lat ahle portion and has four coats: —

Fibrous, continuous with both layers of the triangular liga-
ment : erectile, continuous with that of the spongy body; an
iinstriated muscular layer and a mucous coat,

The spongy portion (pars cavernosa) extends from the
membranous portion through the corpus spongiosum to the
meatus urinarius on the summit of the glans.

The portion within the hulh has received Ihe name of tudh-
ous portion of the urethra. The spongy portion diminishes
gradually in size to near the orifice, where ii suddenly dilates
into the fossa navicularis (fossa navicularis urethra: \_Mor-

282 HUMAN ANATOMY.

gagni] ) , contracting again at the meatus, the narrowest part of
the urethra.

The mucous membrane is provided with columnar epithe-
lium, except near the meatus, where it is tessellated, a fibro-
elastic submucous layer with unstriated muscular fibers, and
numerous minute racemose glands, the glands of Littre (gland-
ules urethrales) . These latter open, forward into the urethra by
good-sized orifices, especially one in the upper part of the fossa
navicularis, called the lacuna magna. Into the bulbous portion
of the urethra the ducts of Cowper's glands open.

The prostate gland (prostata) is a glandular body which
resembles in size and form a chestnut, and surrounds the first
portion of the urethra between the neck of the bladder and the
triangular ligament. It measures one and one-half inches in
length and breadth and three-quarters in depth. Its weight,
about six drachms. Its flat under surface rests on the rectum.

It has two lateral lobes (lobus dexter et sinister), and one
middle lobe (lobus medius), which corresponds in position to
the vesicle uvula, and is held in position by the anterior liga-
ments of the bladder, by a portion of the deep perineal fascia,
and of the levator ani muscle.

It is perforated by the urethra and the common seminal
ducts.

Its structure consists of a mass of flbromuscular (unstri-
ated) tissue with imbedded follicular pouches, the whole inclosed
in a firm fibrous capsule, continuous in front with the trian-
gular ligament, behind with the posterior layer of the deep
perineal fascia.

The muscular fibers are longitudinal and circular, the lat-
ter surrounding the urethra, continuous behind with the blad-
der, in front with the fibers about the membranous portion.

The glands open into the floor of the prostatic sinuses by
twelve to twenty ducts.

The arteries are from the vesical, hemorrhoidal and inter-
nal pudic.

The veins enter into the formation of the prostatic plexus,
receive the dorsal vein of the penis, and empty into the internal
iliac vein.

The nerves are from the hypogastric plexus.

Cowpep/s glands, or suburethral glands (glandulce bulbo-
uretlirales) , are two small lobular bodies, about one-quarter of
an inch in diameter, inclosed between the two layers of the deep
fascia, situated behind the bulb of the corpus spongiosum, below
the membranous portion of the urethra. They are racemose

THE GENITOURINARY APPARATUS. 283

gland- and empty their secretion by a long duct (ductus excre-
iorms) into the bulbous portion of the urethra.

Female Organs.

The female organs of generation are divided into the exter-
nal (partes genitales external muliebres), termed the vulva, or
pudendum, consisting of the mons veneris, labia majora,
minora, clitoris, meatus urinarius and orifice of the vagina ; and
the internal (pars genitales internee muliebris) , consisting of

Fig. 101.
Internal female genitals.

the uterus, ovaries, Fallopian tubes and vagina, with certain
accessories.

The uterus is a hollow, muscular organ for the reception
of the fecundated ovum and the development and expulsion of
the fetus.

The virgin uterus holds an oblique anterior position in the
pelvis, being supported by attachments to the vagina, rectum,
bladder and sides of the pelvis.

It is in contact with the bladder in front, the rectum
behind, and above the small intestine.

Its shape is pyriform, compressed from before backward,
and measures three inches in length, two in breadth, one in
thickness, and weighs from one to one and a hall' ounce-.

J l consists of a nock, fundus and body.

284 HUMAN ANATOMY.

The month, os uteri, or os tineas (orificium uteri exter-
num), open into the vagina, being protected by two lips; an
anterior (labium anterius) thick lip, and a posterior (labium
posterius), long and narrow.

The cavity of the uterus (cavum uteri) is triangular V
from side to side, but a mere slit from before backward, and
measures two and one-half inches in its longitudinal diameter.

The two upper angles are prolonged to communicate with
the Fallopian tubes ; the lower angle forms the ostium internum
uteri (orificium internum uteri), communicating with the cav-
ity of the cervix.

Its structure consists of three coats : —

Serous coat (tunica serosa), derived from the peritoneum
and investing all but the lower anterior quarter ;

Muscular coat (tunica muscularis), about one-half inch
thick, composed of unstriated muscular fibers arranged into
three layers;

Mucous coat (tunica mucosa), has numerous tubular folli-
cles, is lined with ciliated columnar epithelium, and has no sub-
mucous coat to connect it with the muscular coat.

The mucous membrane of the cervix is thrown into folds,
or ruga}, which assume on the anterior and posterior walls a
branched arrangement, or arbor viice uterina. It is lined by
squamous epithelium, and presents numerous follicular glands —
the ovula of Naboth, or glandulce Nabothi.

The arteries are branches of the ovarian from the aorta,
and the uterine from the internal iliac, remarkable for their
tortuosity and anastomoses.

The veins form plexuses or uterine sinuses, the branches of
which correspond to the uterine arteries and terminate in the
uterine plexuses.

The lymphatics are very numerous and terminate in the
lumbar and pelvic glands.

-The nerves are from the ovarian and hypogastric plexus
of the sympathetic.

The ligaments of the uterus are foMs of peritoneum
arranged into four pairs: —

Two anterior, or vesicouterine, passing one on either side from the
posterior surface to the cervix uteri ;

Two posterior or rectouterine {plica rectouterinw) , passing be-
tween the sides of the rectum and uterus, and inclosing a cul-de-sac, the
rectovaginal pouch, or Douglas's pouch;

A prolongation of this ligament upward to the second sacral verte-
bra, with some unstriated muscular fibers derived from the uterus and
vagina, forms the so-called uterosacral ligaments j

THE GENITOURINARY APPARATUS.

285

Two lateral, or broad [Ugamentum latum uteri), extending from
the uterus to the sides of the pelvis, dividing it into two portions, and
inclosing the Fallopian tubes, ovary, ovarian ligament, uterine blood-
vessels, lymphatics and nerves, and some unstriated muscular fibers;

Two round ligaments [Ugamentum teres), are cords of unstriated
muscular and fibrous tissue, extending from the side of the fundus uteri
to the inguinal canal, where they are lost in the subcutaneous tissue of
the pubes and labia majora.

The canal of Nuck, a pouch of peritoneum, incloses the ligament in
the young subject, but is usually obliterated later.

„ UreMiro.

Fig. 102.
Female organs of generation.

The ovaries correspond to the male testicles, and are sus-
pended behind the broad ligament inclosed in its posterior layer.
.They are largest from puberty to adult age, and measure
one and one-half inches in length, three-quarters of an inch in
width, and one-third of an inch in thickness, and weigh from
one to two drachms. The inner border is attached to the fundus

uteri by the ova/nan ligament, and its outer border to the fim-
briated extremity of the Fallopian tube by a cord (tubo-ovarian
ligament).

286 HUMAN ANATOMY.

The structure of the ovary is made up of a reddish, spongy
stroma, well supplied with blood-vessels, containing numerous
ovisacs, or Graafian vesicles (folliculi obphori vesiculori
[Graafi]), inclosed in a serous covering derived from the
peritoneum.

The serous coat differs from the peritoneum in having a
single layer of columnar cells, the germinal epithelium of
Waldeyer.

The stroma of the ovary is a vascular tissue, composed of
many spindle cells and a small portion of connective tissue.
Upon the surface of the ovary, this tissue becomes niore firmly
organized and tenacious; and was formerly, but erroneously,
designated the tunica albuginea.

The Graafian vesicles, or ovisacs, containing the human
ova, vary in size from microscojfic bodies to one-quarter of an
inch in diameter, and are most abundant in the perijDhery.

In structure they consist of a fibrous coat — the ovicapsule —
lined by a basement membrane — membrana propria — and a
layer of cells, the membrana granulosa. The interior is filled
with a transparent 'albuminous fluid, liquor folliculi.

Tbe epithelial lining nearest the ovary presents an accumu-
lation of cells — the germinal eminence, or discus proligerus,
within which is the ovum or egg.

Discharge. — The Graafian vesicles approach the surface of
the ovary and burst, their contents passing into the opened aper-
ture of the tube, the fimbriated extremity apparently applying
it to the region of the bursting ovisac.1

The rupture occurs periodically and corresponds to the
menstrual flow.

The ovum is surrounded by the tunica vasculosa and some
additional epithelial structures (retinacula). It is one-tenth
line in diameter, and represents all the elements of an organized
cell, being composed of a

Cell-wall, or vitelline membrane, or zona pellucida;
Cell-contents, or vitellus ;
Nucleus, or germinal vesicle ;
Nucleolus, or germinal spot.

At the seat of the rupture the walls collapse, and the
vesicle immediately becomes filled with a blood-tinged fluid,
which, together with the hypertrophy of the walls, forms the

l The fimbriated extremity contains no erectile tissue, and the
ovum probably falls into the peritoneal cavity and is swept into the
tube by the action of the cilia. (Spigelberg.)

THE GENITOURINARY APPARATUS.

287

false corpus luteum, which remains and develops for two to
three months and gradually disappears.

Under the influence of pregnancy it enlarges for some time,
forms the true corpus luteum of pregnancy, and disappears two
lo three months after parturition.

The arteries are the ovarian from the aorta.

The veins form an intricate plexus from which emerge ves-
sels corresponding to the* arteries; they form a plexus near the
ovary — the pampiniform plexus — which communicates with the
uterine and terminates as in the male.

The lymphatics are numerous and of large size in the

FIG. 103.

Section of an ovary: e, germ epithelium; 1, large-sized follicles;
2, 2, smaller-sized follicles; 0, ovum within a Graafian follicle; r, r,
blood-vessels of the stroma; (J, cells of the membrana granulosa.

impregnated uterus, and terminate in the lumbar and pelvic
glands.

The nerves are from the ovarian and thoracic aortic plexuses
of the sympathetic.

The Parovarium, epo6phoron or organ of Etosenmuller, con-
sists of a series of tortuous tubes extending from the ovary to a
main transverse trunk, near the Fallopian tubes; and is the re-
main- of the Wolffian body of embryonic Life, and corresponds to
the origin of the epididymis in the male.

Tin- Fallopian tubes, or oviducts {tuba ulcriiia FallopU),

are the passageways for the ovum from (he ovaries to the uterus.

288 HUMAN ANATOMY.

They are trumpet-shaped tubes about four inches long, with the
largest extremity outward.

Its ovarian extremity is fimbriated; hence its name, fim-
briated extremity. It is also called morsus diaboli, from its
supposed erectile action.

One of these fimbriae extends along the border of the broad
ligament to the outer extremity of the ovary, forming the tubo-
ovarian ligament {fimbria ovarica).

The ovarian orifice — ostium abdominale, or pavilion (os-
tium abdominale tubce uterince) — is much larger than the
uterine, or ostium internum (ostium uterinum tubce).

The tube has three coats: —

Serous (tunica serosa), derived from the peritoneum;

Fibromuscular (tunica muscularis, stratum longitudinale
et stratum circular e) , from the uterine walls;

Mucous coat (tunica mucosa), with ciliated columnar epi-
thelium, continuous with the uterine.

The remains of the duct of Mtiller form the hydatid of
Morgagni (appendices vesiculosi) , a small vesicle, attached by
a long pedicle near the fimbriated, extremity.

The arteries are from the ovarian, the veins follow the
same course, and the lymphatics and nerves are the same as the
ovarian and uterine.

The vagina is a cylindrical membranous canal extending
from the vulva to the uterus. It is formed by the coalescence
of two symmetrical tubes in fetal life.

Relations. — It is in relation in front with the base of the bladder
and urethra, behind its upper fourth with Douglas's pouch, its lower
three-fourths connected loosely with the rectum, and laterally with the
broad ligaments, pelvic fascia and levator ani muscles.

On the posterior wall just below the cervix uteri the -ureters
approach each other, leaving a space of only three-quarters of
an inch between them, an important factor in lithotomy.

In the virgin adult it measures about four inches in length,
one inch in width, somewhat larger in its middle. Its anterior
(paries anterior) and posterior walls (paries posterior) are in
contact.

Its lower orifice, or entrance (orificium vagina), is con-
stricted by a crescentic or circular fold, of mucous membrane,
the hymen.

The upper extremity, or fundus, receives the cervix uteri,
extending higher up posteriorly (five to six inches), making
the anterior lip apparently the longest.

THE GENITOURINARY APPARATUS.

289

The mucous membrane has numerous transverse folds, or
rugae (rugce vaginales), passing to either side of a median ridge,
both anterior and posterior, the columnae vagina' (columnm
rugdrum anterior et posterior), formed by the coalescence of
the two tubes in fetal life. Some of these rugae present wart-

MONS VENERIS

fe?

<v

MEATUS
-URINARIUS

kJ

Fig. 104.
External female genitals. (Eckley.)

like eminences, most numerous about the entrance of the vagina,
.where they form the caruneulae myrtiformes {cwrwricvXcB liyme-
nales), the remains of the hymen after intercourse (or after
parturil ion — Budin).

The (trails of the vagina are about one line thick and con-
-i-i of three coats: —

19

290 HUMAN ANATOMY.

Muscular coat (tunica muscularis), of unstriated fibers,
elastic tissue and blood-vessels, consisting of two layers, external
longitudinal and internal circular, and about the entrance the
internal circular fibers form the sphincter vagince (vide Peri-
neum) ;

An erectile coat, largely composed of loose connective tis-
sue, imbedded in which are many large veins and unstriped
muscular fibrous tissue. This erectile coat is found between the
mucous membrane and the muscular coat.

Mucous or internal coat (tunica mucosa), containing nu-
merous conical papillae, and covered by squamous epithelium.

The arteries are from the vaginal, uterine, vesical and
internal pudic.

The veins form an intricate plexus on each side with the
returning vessels, corresponding to the prostatic plexus, and join
the internal iliac veins.

The nerves are from the hypogastric plexus of the sympa-
thetic, also the fourth and fifth sacral and internal pudic nerves.

The vulva, or pudendum (pudendum muliebre) , consists of
the mons veneris, labia majora and minora, clitoris and meatus
urinarius.

The mons veneris (mons pubis) is the prominence of skin
over the symphysis pubis, supported upon a mass of adipose
tissue, and covered with hair.

The labia majora (labia majora pudendi) are two folds of
skin bounding the vertical fissure of the labia (rima pudendi),
the junctions of which in front and behind form the anterior
(commissura labiorum anterior) and posterior (commissura
labiorum posterior) commissures. The labia correspond to the
scrotum in the male.

Within the posterior commissure is a depression, fossa na-
vicularis (fossa navicularis veslibuli vagince), which separates it
from a fold of mucous membrane — the fourchette (frenulum
labiorum pudendi) .

The triangular space between the anus and the posterior
commissure is termed the perineum.

The clitoris corresponds to the penis in the male, resem-
bling it also in form, structure and connections.

It is about one and one-half to two inches in length, and
consists of a pair of corpora cavernosa, and a double, spongy .
body (corpus clitoridis), surmounted by a free extremity (glans
clitoridis) .

The corpora cavernosa (corpus cavernosum clitoridis) arise
by two crura attached to the rami of the pubes and ischium like

THE GENITOURINARY APPARATUS. 291

the penis, and united in front by the septum pectiniforme.
They curve abruptly down, being attached to the pubic sym-
physis by a suspensory ligament. The body and crura represent
a tripod.

The free extremity (glans clitoridis) corresponds to that of
the male penis, but is not perforated by the urethra. It is
covered bv the praputium clitoridis, a hood-like fold of skin
continuous with the nymphae.

The corpus spongiosum consists of an intermediate portion
and semibulbs. The former consist of a plexus of veins, in-
closed in a fibrous membrane.

The semibulbs, or bulbi vestibuli, are about the size of large
almonds, and are situated beneath the vestibule, embracing the
orifices of the urethra and vagina. In front of the bulbs, be-
tween them and the clitoris, is a smaller plexus called the pars
intermedia.

The arteries, nerves, and veins are the same as those of the
penis.

The nymphae, or labia minora (labia minora pudendi), are
two folds of mucous membrane diverging from the praputium
clitoridis to the labia, where they are lost. At their superior
extremity they divide into two folds, the upper forming the
prceputium clitoridis, the lower ones are usually lost in women
who have borne offspring. In the non-pregnant female they
usually unite behind, forming a fold, designated the frenum
(frenulum clitoridis).

These diverging labia inclose a triangular space, the vesti-
bule (cestibuliuii vagina), at the middle of the base of which
is situated the orifice of the urethra, or meatus urinarius,
(crifi tin in urethra externum).

The bladder in the female is larger and broader than in
the male. It is situated behind the pubes, in front of the
uterus, from which it is separated by the small intestine, and
rests upon the anterior wall of the vagina and cervix uteri.

The urethra is a short but capacious canal, one and one-
half inches in length, one-quarter inch in diameter, extending
beneath the pubic symphysis from the neck of the bladder to
the externa] urinary meatus. It lies in the anterior wall of tin'
vagina, and perforates the triangular ligament precisely as does
the male urethra (vide Urethra)'.

Below the vestibule is the entrance or orifice of the vagina
(orificium vagina). The mucous membrane of the labia is
reflected continuously to the clitoris, aymphse, prepuce and
vestibule, and becomes continuous with the vagina and urethra.

292 HUMAN ANATOMY.

Its epithelium is squamous, and its glands racemose, mu-
cous and small sebaceous glands (glandulce Tysonii odoriferce).

The Bartholin or suburethral glands (glandula vestibularis
major [Bartholini]) are two racemose glands about one-third
inch in diameter, situated just behind the semibulbs of the
spongy body. The ducts, about three-fourths inch long, open
between the nymphse and the vaginal orifice, or the hymen, if
present. They secrete mucus.

The blood vessels and nerves of the vulva correspond to
those of the penis and scrotum (vide Internal Pudic Artery).

MAMMARY GLAND.

The mammae, or breasts (mamma), are the milk-secreting
organs of the female (being rudimentary in the male). They
consist of two large, hemispherical bodies (corpus mamma), in
the anterolateral region of the thorax, resting upon the pecto-
ralis major muscle, between the third and seventh ribs, inclosed
between the two layers of the superficial fascia.

The nipple (papilla mammce) - is roseate or brownish, and
surrounded by an areola (areola mamma?) of the same color,
the skin of which contains numerous sebaceous glands, the
tubercles of the areola, or the glands of Montgomery (glandulce
areolares). The skin of the nipple is thin, vascular and erectile.
On its summit are the orifices of the fifteen to twenty milk-
ducts, or lactiferous ducts.

Its structure is firm and pinkish white, consisting of fifteen
or twenty lobes (lobi mamma'), forming a racemose gland, held
together and invested with fibrous tissue.

Each lobe ends in one of the tubuli lactiferi, or galacto-
phori (ductus lactiferus) , which beneath the areola dilates into
a lactiferous sinus, or galactophorus sinus, or ampulla (sinus
lactiferans) , and terminates on the summit of nipple in an
orifice.

The arteries are, the long thoracic, with other branches of
the axillary, the internal mammary and intercostals.

The veins follow the corresponding arteries to end in the
internal mammary and axillary veins. They form about the
base of the nipple a venous circular anastomosis, the circulus
venosus.

The lymphatics terminate in the axillary glands, a few also
entering the anterior mediastinal glands.

THE GENITOURINARY APPARATUS. 293

The nerves are from the fourth, fifth and sixth intercostal*,
with sympathetic filaments from the dorsal cord.

Milk, the secretion of the mammary gland, is an emulsion,
consisting of a colorless fluid, the mil I- -plasm a, holding in sus-
pension the milk-globules. It has a specific gravity of 1.028 to
1.034, and slightly alkaline reaction.

THE NERVOUS SYSTEM.

The nervous system, for description, is divided into two
parts : central and peripheral.

The central nervous system, cerebrospinal axis, or enceph-
alospinal axis, or neuraxis, consists of the brain and spinal cord,
and also comprises certain exterior ganglia.

The peripheral nervous system consists of the cranial and
spinal nerves and ganglia, and the sympathetic nerves and
ganglia.

The nervous system may also be divided into the cerebro-
spinal system, that supplying muscles, skin, and mucous mem-
branes; and the sympathetic system, presiding over organs and
blood vessels.

Structure. — Nervous tissue consists of three distinct sub-
stances, combined in variable proportions in the different parts
of the nervous system (white, or fibrous substance; gray, cineri-
tious, or vesicular substance, and neuroglia)..

(a) White substance is found in the cortex of the cord, the
interior of cerebrum, in nerves, etc., and is made up of medul-
lated nerve fibers. These are smooth, round fibers, measuring
one-two-thousandth to one-twelve-thousandth of an inch in
diameter, and have each three parts : —

1. Axis cylinder of Purkinje is a round or bandlike striated
structure consisting of fibrillar, called the primitive fibrillar of
Schultze. There is said to be an envelope of tissue around, this
composed of a substance called neurokeratin;

2. The medullary sheath, or white substance of Schwann,
is made up of fatty matter in a fluid condition and probably
insulates the axis cylinder; and

3. The neurilemma, or sheath of Schwann, a delicate, struc-
tureless membrane, closely surrounding the medullary sheath,
and forming the surface of the nerve fibers.

Near their termination the nerve fibers lose their medul-
lary sheath and become non-medullated (Eemak's) fibers. Such
are the olfactory and most of the sympathetic nerves.

(b) Gray substance, found in the middle of the spinal
cord, in the cortex of the brain, in ganglia, etc., consists of

(294)

THE NERVOUS SYSTEM.

295

throe elements: (1) nerve fibers; (2) nerve cells; and (3)
blood vessels and connective tissue.

Nerve fibers. — The nerve fibers are the prolongation of the
nerve cells. If there be but one process it is termed the axone,
axis cylinder, or Dietrich's process. If there be more than one
there is one which is the axone and the rest: are called dendrites,
or protoplasmic processes. There are two kinds of fibers, med-
ullated and non-medullated.

Nerve cells are of three kinds, according to the number of
their processes: unipolar, bipolar and multipolar cells.

A neuron is the term given to a nerve cell with its axone,
or axis-cylinder process, and its dendritic processes. Each neu-
ron is a distinct and separate unit. According to the neuron
theory the neurons mass together to form cell groups and fiber
systems. Each neuron is not joined to the other neurons, but
is in contact with them. Process touches process or process
touches cell. The. neuron theory is as yet not firmly established
and a new theory, that of Apathy and others, claims that the
chief constituents of the nervous system are neurofibrils which
go from cell to cell.

(c) Neuroglia, the supporting framework of nerve tissue,
is made up of a matrix of delicate, fibrillar network and small
neuroglia cells, and forms an imbedding substance for the other
elements.

Nerves are round, or flattened white, shining cords, belong-
in- either to the cerebrospinal or the sympathetic systems.
They are made up of bundles of nerve fibers held together by
fibroconnective tissue, the epineurium. The individual fibers are
held together within the bundles by connective tissue, the endo-
neurium.

The nerve fibers have a twofold function — sensory and
motor.

Sensory, or afferent, transmit impressions from the periph-
ery to the centers.

Mo/or, or efferent, transmit impressions from the centers
io the periphery.

Ganglia form independent nerve centers, similar to but Less
complex than the brain. They are connected with some of the
cranial nerves, all of the spinal nerves, and form an important
part of the sympathetic system.

Terminations.- The motor uerves end in the voluntary and
involuntary muscles, the former having special endings called
the motortal end plates.

296 HUMAN ANATOMY.

The sensory nerves terminate in the peripheral organs to
which they are distributed by first becoming non-medullated,
and then dividing and joining one another to form a minute
plexus or by means of one of the five special endings, called
"peripheral end organs": (1) tactile corpuscles of Wagner; (2)
end bulbs of Krause; (3) the Pacinian corpuscles; (4) neuro-
tendinous spindles; or (5) neuromuscular spindles.

CEREBROSPINAL AXIS.

The cerebrospinal axis is divided into two grand divi-
sions : —

The encephalon, or brain and spinal cord.

Membranes of the Brain. — The membranes of the brain
(meninges encephali) are three — dura mater, arachnoid and
pia mater.

Dura mater (dura mater encephali) is a dense, white,
fibrous membrane lining the interior of the skull, and forming
its internal periosteum, to which it is tightly adherent at the
sutures.

It contains the sinuses or venous channels (already de-
scribed), and forms four partitions for the support of the
brain — the falx cerebri, falx cerebelli, tentorium cerebelli and
diaphragma sella;.

Falx cerebri is an arched or sickle-shaped process received
into the longitudinal fissure. It contains in its upper and lower
margins the superior (sinus sagittalis superior) and inferior
(sinus sagittalis inferior) longitudinal sinuses and forms by its
attachment to the tentorium the straight sinus (sinus rectus).

Tentorium cerebelli is a lamina, arched across, between the
superior borders of the petrous portion of temporal on either
side, the anterior and posterior clinoid processes in front, the
transverse , ridge of the occipital behind, for the support of
the posterior lobes of the cerebrum. It incloses the superior
petrosal (sinus petrosus superior) and the lateral sinuses (sinus
transversus) .

Falx cerebelli is a small median, triangular partition de-
scending from the tentorium to the foramen magnum, and
separating the lateral lobes of the cerebellum.

Diaphragma sella? is a horizontal process formed by a doub-
ling of the meningeal layer of the dura mater. It forms a
small circular fold which roofs the sella turcica and covers the
pituitary body, leaving a small central opening (foramen dia-
phragmatic sella:).

mi-: NERVOUS SYSTEM. 297

The arachnoid (arachnoidea encephali) is a thin, trans-
parent, delicate membrane consisting of fibrous and elastic tis-
sue, situated between the dura and pia mater. From the
former it is separated by the subdural space (cavum sub-
durale) : from the latter, by the subarachnoid space {varum sub-
arachnoideale ) .

\ nlike the pia mater, it does not dip into the sulci on the
brain surface, excepl by the Sylvian and great Longitudinal
fissure-.

The subarachnoid Bpace contains cerebrospinal fluid, and
communicates through certain foramina with the cavities of the
brain. The space is much broken up by loose connective tissue,
which connects it to the pia mater.

The three expanded portions of the subarachnoid space are
the cisterna magna, cisterna pontis and cisterna basalis.

The cisterna magna (cisterna cerebellomedullaris) , or pos-
terior subarachnoid space, is placed over the roof of the lower
portion of the fourth ventricle, and communicates with the
fourth ventricle by the foramen of Majendie and two smaller
foramina: those of Keves and Retzius.

Tlie anterior subarachnoid space (cisterna pontis) is placed
in front of the pons Varolii.

The cisterna basalis (cisterna interpeduncularis) incloses
the circle of Willis.

The Pacchionian bodies (granvlationes arachnoid eales) are
projections of the arachnoid into, but not through, the dura
mater, and are most numerous along the great longitudinal
sinus. They make impressions on the under surface of the cal-
varium. from which, however, they are separated by a thin layer
of dura mater. Their function is to allow the passing of fluid
from the subarachnoid space into the brain-sinuses when the
blood pressure in the Binusee is lower than in the subarachnoid
space.

Pia mater (pia mater encephali), the investing membrane
of the brain, is composed of a network of blood vessels derived
from the vertebral and internal carotid arteries, held together
by delicate connective tissue. It dips into the sulci, and is pro-
longed into the ventricles, forming the velum interposition
(tela chorioidea ventricidi tertvi)', or tela choroidea superior and
the tela choroidea inferior (tela chorioidea ventriculi quarti).
The former covers the third ventricle and extends into the
lateral ventricles, carrying in its margins the choroid plexus of
the lateral ;md third ventricles. It is perforated by two slitlike
foramina, one communicating with each lateral ventricle.

298

HUMAN ANATOMY.

The tela choroidea inferior (tela choroidea ventriculi
quarti) forms the roof of the lower part of the fourth ven-
tricle. It contains nerves and lymphatics.

The Beain (The Encephaixw) .

The brain (enceplialon) consists of four distinct portions:
the cerebrum, cerebellum, pons Varolii and medulla oblon-
gata. The average weight of the brain in the male adult is
forty-nine and a half ounces, in the female forty-four ounces,'
of which the cerebrum is about seven-eighths of total weight.
The maximum male brain weighs sixty-five ounces; minimum,
thirty-four ounces. The maximum female brain weighs fifty-six
ounces; minimum, thirty-one ounces. The brains of idiots sel-
dom weigh more than twenty-three ounces. Excepting the whale
and elephant, the human brain is heavier than that of all the
lower animals.

The brain is developed from the anterior portion of the
primitive neural tube. This expands and later becomes con-
stricted into three primary brain-vesicles, which are called the
fore-brain (prosencephalon), mid-brain (mesencephalon), and
hind-brain (rhombencephalon). The fore-brain becomes differ-
entiated later into the telencephalon and diencephalon ; and the
hind-brain likewise is differentiated into two parts : the meten-
cephalon and the myelencephalon.

From these brain-vesicles are developed the following: —

Brain or
Encephalon,

Rhomben-
cephalon, or
hind-brain,

Mesen-
cephalon, or
mid-brain,

'Myelenceph-
alon,

Metenceph-
alon.

(Medulla oblongata,
Lower part of fourth
ventricle.

f Cerebellum,
j Pons Varolii,
i Upper part of fourth

j ventricle.

Isthmus rhom- ~)

bencephali ] s ior cerebellar pe-
( narrow part ■

connecting
with mesen-
cephalon

y duncles,

Valve of Vieussens.

>> J

{Mesenceph-
alon, or mid-
brain,

{Corpora quadrigemina,
Crura cerebri,
Aqueduct of Sylvius.

THE NERVOUS SYSTEM.

299

Brain or
Encephalon.
[continued i

Prosen-
cephalon,
fore-brain

Thalamanceph-
alon, or dien-
cephalon,

or J

Optic thalami,
Subthalamic regions,
Pituitary and pineal

bodies.
Structures in interpe-
duncular space.
Optic nerve and retina.
Hinder part of third
ventricle.

Cerebral hemispheres,
Olfactory lobes,
Lateral ventricles,
Telencephalon < Foramina of Monro,
j Anterior portion of
i third ventricle.

The medulla oblongata (myelencephalon) is the upper
expanded portion of the spinal cord, extending between the
lower border of the pons and the upper border of the atlas. It
is divided by two fissures — the anterior (fissura mediana ante-
rior) and posterior median (fissura mediana posterior) fissures
— into two halves, each one of which is subdivided into four
columns, from before backward, the following: —

(a) Anterior pyramids (pyramis medulla? oblongata') , or
corpora pyramidalia, are two pyramidal masses of white nervous
matter, placed between the anterior median fissure and the
olivary body, and continuous with the anterior columns of the
cord below ;

(b) Lateral tract and olivary body, are continuous with
the lateral columns of the cord below;

(c) Eestiform bodies (corpus restiforme) are continuous
below with the posterior columns of the cord. They are com-
posed of the fibers of the columns of Goll and Burdach and the
direct cerebellar tract. They diverge, the interval between them
being the lower portion of the fourth ventricle.

The structure of the medulla oblongata consists of both
white and gray matter, the former arranged into four columns,
the latter contained in the interior.

The gray matter of the medulla is partly arranged into
- and partly continuous with the gray matter of the cord.
The posterior horns are called here "the tubercles of Rolando"
(tuberculum Eolandi). On the floor of the fourth ventricle
{fo<sa rhomboidea) the ganglion-cells are arranged into nuclei,
from which several of the cranial nerves have their origin.

300

HUMAN ANATOMY.

The Pons Varolii connects the cerebrum above with the
cerebellum behind and the medulla oblongata below. On its
under surface it presents a groove (sulcus basilaris) for the

Oan.

Op.ch

Suits- iri'b

Bk I-P.C.

a

V,mfty y-l^

Fig. 105.

Surface anatomy of the niyelencephalon. Roman numerals refer
to cranial nerves.) C. 1, first cervical spinal nerve; C. mam, corpus
mammillare; Op. n., optic nerve; Inf., infundibulum; Op. ch., optic
chiasm; Subs, int., substantia interpeduncugeniculate body; Sub. b.,
basilar sulcus; M. p. c, middle peduncle of cerebellum; F., flocculus;
F. h., horizontal fissure; 0., olive; T. I. s., ventrolateral sulcus; Pyr.,
pyramid; V. m. f., ventral median fissure. (Whitehead, after Van
Qehuchten.)

passage of the basilar artery. The upper surface forms a por-
tion of the floor of the fourth ventricle (fossa rhomb oidea) , and
on either side, under the name of the crus, passes, to the cere-
bellum, forming its middle peduncle (brachia pontis).

THE NERVOUS SYSTEM.

301

CEREBELLUM.

The cerebellum, ot little brain, occupies the inferior occip-
ital fossae beneath the great cerebral Lobes, from which it is

separated by the tentorium. Its average weight is a little over
five ounces in the male, and is proportioned to the greater brain
about one to twenty. It is oblong, flattened from above down-
ward, and divided into two lateral hemispheres connected by a
central portion, the vermiform process (vermis).

It is composed of gray and white matter — the former upon
the surface. It is not convoluted, like the cerebrum, but con-
>i>t> of a number of thin plates, folia, arranged in a series of
crescent ic curves, with the concavity forward.

The cerebellum consists of a central lobe (vermis), and
two lateral hemispheres (Itemisphcrria cerebelli). The latter
are separated on the inferior surface of the cerebellum by a
deep hollow, the valley or vallecula (vallecula, cerebelli), which
Lodges the medulla oblongata. The floor of the vallecula is
formed by the inferior portion of the vermis.

The incisura semilunaris (incisura cerebelli anterior) sep-
arates the hemispheres in front, and rests against the corpora
quadrigemina;

The incisura marsupialis (incisura cerebelli jiostrrior)
separates the hemispheres behind, and receives the upper por-
tion of the falx cerebelli ;

The great horizontal fissure (sulcus horizontalis cerebelli)
separates the cerebellum into a superior and an inferior surface.

The upper surface (fades cerebelli superior) shows the
superior vermis (vermis superior cerebelli), with its correspond-
ing Lobes in the hemispheres. These latter are separated from
each other by fissures. The following table gives the arrange-
ment of the lobules : —

G

beat Horizontal

ElSSIRE.

Pre-

Frsenulum

Lingula.

Frsenulum

central fissure

Post-

Ala.

rJbbus cenl ral is.

Ala.

Anterior

Anterior

crescentic

Lobus culminis.

crescent ic

I'n-

lobe.

lobe.

Posterior

Posterior

crescent i(-

Lobus cljvi.

crescenl ic

lobe.

lobe.

I'o-I

Posterior

Posterior

Great

superior
lobe

Folium cacuminis.

superior
lobe.

horizontal
fissure.

302

HUMAN ANATOMY.

The inferior surface (fades cerebelli inferior) of the cere-
bellum presents the deep depression, the vallecula, which ren-
ders the connection between the vermis and the hemispheres
less intimate. The divisions of the vermis and their correspond-
ing lobules in the hemispheres are as follows : —

Great

Post-

Pre-

Post-

Great

Slender lobe,
post-gracile,
posterior in-
ferior lobule.

Lobulus
biventer.

Amygdala.

Flocculus.

Tuber valvulse

Pyramis.

Uvula.

Nodule.

Posterior
inferior
lobule.

Lobulus
biventer.

Amygdala.

Flocculus.

horizontal
fissure.

pyramidal
fissure.

pyramidal
fissure.

nodular
fissure.

horizontal
fissure.

The cerebellum is connected with the encephalon by the
peduncles of the cerebellum,, three in number, from above down-
ward, as follows : —

Crura ad cerebrum, superior cerebellar, peduncles, or
processus e cerebello ad testes (bracliia conjunctiva cerebelli),
pass to the cerebrum ;

Crura ad posterior, middle cerebellar peduncles, or proces-
sus ad pontem (bracliia pontis), the transverse fibers of the pons
Varolii, connect the hemispheres;

Crura ad medullam, inferior cerebellar peduncles or proces-
sus e cerebello ad medullam, the restiform bodies of the medulla
oblongata (corpora restiformia), connect with medulla ob-
longata.

. The internal structure of the cerebellum consists of an
arbor vitge arrangement of gray matter, inclosing a white mass.
In center of the latter is found a grayish, dentated mass, the
corpus dentatum (nucleus dentatus), an irregular capsule of
gray matter opening anteriorly.

TITE CEREBRUM

consists of a large, ovoidal mass, divided into two lateral halves,
or hemispheres (hemisphmria cerebri), by the great longitudinal

THE NERVOUS SYSTEM.

303

fissure (fissura longitudinalis cerebri), connected by a white
Transverse commissure — the corpus callosum. The surface is
irregularly marked by convolutions, or gyri (gyri cerebri),
separated from each other by irregular depressions, fissures
( tis.<nru) . or sulci (sulci cerebri). The outer surface is com-
posed of gray matter, which, from its location, is called the
cortical substance. The interior surface, for the most part, is

white.

&?<■■ J/t. J.poste,

S.ieft/p

Lift side of human cerebrum. »S'. fr. s., superior frontal sulcus;
8. prase, precentral sulcus; 8. R., central sulcus of Rolando; 8. poste.,
Post-central sulcus; 8. Interp., interparietal sulcus; 8. p. o., parieto-

i ItaJ fissun : Hunt. post. 8., posU rior ramus of fissure of Sylvius;
8. temp. in., middle temporal sulcus; 8. temp. 8., superior temporal
sulcus; /•'. 8., fissure of Sylvius; R. ant. 08C. 8., ascending anterior
ramus of fissure of Sylvius; R. s. h. 8., horizontal anterior ramus of
fissure of Sylvius; 8. fr. inf., inferior frontal sulcus. (Whitehead,
after Van Oehuchten.)

The principal fissures of the brain are five, as follows: —

]. The great longitudinal fissure (fissura longitudinalis cerebri),
separating tin- two hemispheres from one another.

■>. The great transverse fissure of Bichal (fissura cerebri trans-
betweeen the cerebellum mid the cerebrum, admitting the pia
mater to form tin- velum interpositum.

.;. The fissure of Sylvius -fissura cerebri lateralis [Sylvii]), be-
ginning at tin- anterior perforated apace and ascending obliquely.

304 HUMAN ANATOMY.

4. The fissure of Rolando {sulcus centralis [Rolandi]), descends
from near the middle of the great longitudinal fissure to join the fissure
of Sylvius.

5. The parieto-occipital fissure {sulcus occipitoparietalis) , on the
postero-Iateral aspect of the cerebrum.

6. The callosomarginal fissure {sulcus singulus) .

7. The collateral fissure {fissura collateralis) .

8. The limiting sulcus of Reil (sulcus circularis [Reili]).

The principal lobes of the brain are six, as follows : — ■

1. Frontal lobe- (lobus frontalis) , on the outer surface of the brain;
it is bounded below by the fissure of Sylvius, and behind by the fissure
of Rolando. On the mesial surface it is bounded by the callosomarginal
fissure, and on the inferior surface it is bounded behind by the stem of
the Sylvian fissure.

On the outer surface it is divided into the

(a) Ascending frontal convolution {gyrus frontalis as-
cendens) ;

(b) Superior frontal convolution (gyrus frontalis superior);

(c) Middle frontal convolution (gyrus frontalis medius) ;

(d) Inferior frontal convolution (gyrus frontalis inferior) ;
On the mesial surface it is divided into

(a) Marginal gyrus (gyrus marginalis) ;

(b) Paracentral lobule (lobulus paracentralis) .
On the orbital surface it is divided into

(a) Internal orbital convolution (gyrus orbit alis internus) ;

(b) Anterior orbital convolution (gyrus orbitalis anterior) ;

(c) Posterior orbital convolution (gyrus orbitalis posterior) .

2. Parietal lobe (lobus parietalis) , lies between the fissure of
Rolando, the parieto-occipital, and the fissure of Sylvius, and consists
of five gyri : —

(a) Ascending parietal (gyrus

centralis posterior) ;
(6) Superior parietal (lobulus

parietalis superior) ; f Supra-marginal (gyrus supramar-

(c) Inferior parietal (lobulus I ginalis) ,

parietalis inferior ) , '■ Angular (gyrus angularis),

*- Post parietal;

3. Occipital lobe (lobus occipitalis) lies at the posterior aspect
of the cerebrum and is divided into first, second and third occipital
convolutions.

4. Temporosphenoidal lobe or temporal lobe (lobus temporalis) ,
occupies the middle fossa of the skull.

5. Island of Reil, or central lobe, lies within the fissure of Sylvius.
It consists of six convolutions — the gyri operti.

6. The limbic lobe surrounds the corpus callosum. Its extremities
are united by the roots of the olfactory tract.

The inner or median surface of the hemispheres presents
five fissures, as follows : —

1. Callosomarginal (sulcus cingulus) .

2. Parieto-occipital (sulcus occipitoparietalis).

3. Calcarine (fissura. calcarina) .

4. Occipitotemporal or collateral (fissura collateralis) .

5. Dentate fissure, or sulcus hippocampi (fissura hippocampi).

THE NERVOUS SYSTEM.

305

The lobes on the internal surface are six in number, as

follows : —

1. Callosal convolution {gyrus formcatus or gyrus cinguli), de-
scends as the gyrus hippocampi and terminates as the uncinate gyrus.

•1. Marginal (gyrus marginaUs), or first frontal convolutions.

3. Quadrate (projcuneus) .

4. Cuneus, or occipital lobule (lobus occipitalis).

5. Uncinate gyrus.

6. Temporosphenoidal lobe or temporal lobe (lobus temporalis).

Sul C.C.

Su?.ima>J-

Sulsuhf'

Sulsubp

FlS.p-Q;

..sSulcalmiy

fis. c&k.

Fig. 107.

Convolutions and ficsures of the median and tentorial surfaces of
the right cerebral hemisphere. Fis. 8., fissure of Sylvius; Sul. cat.
marg., callosomarginal sulcus; Sul. subf., subfrontal sulcus; Sul. C. 0.,
sulcus of corpus callosum; Sul. marg., marginal sulcus; Sul. subp.,
subparietal sulcus; Fis. p. o., parieto-occipital fissure: Fie. calc, cal-
carine Bssure; Fis. den., dentate Assure; Fis. col., collateral fissure.
{Whitehead, after Van Qehuchten.)

The inferior surface (fades basalis encephali) of each.
hemisphere lb divided into three lobes — the anterior, middle
and posterior. The two former occupy the anterior and middle
fossa of the skull and the posterior rests upon the cerebellum,
separated from it by the tentorium. This surface presents for
study from before backward the following points: —

The longitudinal fissure (fissura longitudinalis cerebri), separates
the two hemispheres;

Corpus calloan in. the great transverse commissure of the cerebrum,
extending bj means of its peduncles to near the Sylvian fissure;

20

306 HUMAN ANATOMY.

[Aim ina eincrca. is ;\ thin, gray layer, forming the anterior part of
the inferior boundary of the third ventricle:

Olfactory nerve, with it* bulb;

Fissure of Sylvius [fissura cerebri lateralis [Sylvii]), between the
anterior and middle lobes of the cerebrum, and lodges the middle cere-
bral artery:

Anterior perforated space (locus perforatus anticus or substantia
perforata anterior), transmits vessels to the corpus striatum:

Optic commissure [chiasma optieum). is formed by the junction of
the optic tracts;

Tuber cinaeutn. is a gray eminence between the corpora albicantia
and optic tracts, and forms part of the tloor of the third ventricle:

Infiindibuluni, is a tube of gray matter connecting the pituitary
body with the third ventricle:

Pituitary body {hypopht/sis cerebri), is a small, vascular, bilobed
body, connected by the infundibulum and occupying the sella turcica
(for histology vide '•Ductless Glands");

Corpora albicantia. or mammillaria. are two white, rounded
masses, formed by the folding of the anterior crura of the fornix, and
are sometimes called the bulbs of the fornix:

Posterior perforated space [locus perforatus posticus: or sub-
stantia perforata posterior) . allows the passage of blood-vessels to the
optic thalami;

Crura cerebri (pedunculi cerebri), or cerebral peduncles, connect
the cerebrum with the medulla, cerebellum, and spinal cord: they con-
sist of the anterior portion, or crusta. and the posterior portion, or
tegmentum, between which is a mass of gray matter — the locus niger:

Pons Varolii, covers up the posterior portion of the cerebral lobes.

Interior of the Cerebrum. — The interior of the cere-
brum, viewed above the level of the corpus eallosum. presents
a white surface — the centrum ovale minus, the margins of
which are convoluted gray matter, and are called labia cerebri.
It is studded throughout with minute blood vessels — puncta
vaseulosa.

The hemispheres, viewed on a level with the corpus eallo-
sum. present a large white mass — the centrum ovale majus — in
the center of which is the connecting band, the corpus eallosum.

Corpus Calhmim. — This connecting band forms the roof
of the lateral ventricles. It is about four inches in length and
varies from an inch and a halt' to two inches in width, present-
ing in front a bend, or genu (genu corporis caUosi). below
which it terminates in the tuber einereum through the lamina
cinerea.

Posteriorly it forms a thick, rounded fold — the splenium
(spleniutn corporis caUosi). or pad — which is continuous with
the fornix.

The peduncles of the corpus eallosum ( gyrus subcallosus or
peduncular corporis caUosi) are two reflected bundles of white
matter given off near the anterior termination of the corpus,

THE NERVOUS SYSTEM.

307

and each passing backward across the anterior perforated
space of its own side to the fissure of Sylvius.

The superior surface of the corpus callosum shows a de-

Julfitf.

Fig. 108.

Inferior aspect of cerebral hemisphrro. Bui. <>lf., olfactory sulcus;
Bui. tim/i. inf.. Inferior temporal sulcus; Fis. col., collateral fissure.
{Whitehead, after \'<m Oehuchten |

pression — tlie raphe — bounded <>u each Bide by elevated bands,
the stria longitudinales, or nerve- of Lancisi. Externa] to these
are the stria longitudinaJes laterales. On either side of the

308 HUMAN ANATOMY.

raphe are many transverse lines — the linear transversa?, which
indicate the direction of the fibers of the corpus.

The cerebral commissuees are connecting bands of gray
and white matter, pursuing either a transverse or anteroposte-
rior course.

Transverse: —

Anterior (commissura anterior cerebri), middle, gray, or soft com-
missure (massa intermedia or commissura mollis), and posterior com-
missure ;

Corpus callosum;

Optic chiasm (chiasma opticum) ;

Fornix ;

Pons Varolii;

Posterior medullary velum (velum medullare posterius).

A n tero posterior : —

Corpus callosum (nerves of Lancisi) ;

Fornix ;

Fasciculus uncinatus (uncinate fasciculus) ;

Taenia semicircularis (stria? terminalis) ;

Callosal convolution (gyrus fornicatus) ;

Inferior longitudinal fasciculus (fasciculus longitudinalis inferior) ;

Olfactory tracts (tractus olfactorius) ;

Crura cerebri (pedunculi cerebri) ;

Peduncles of pineal gland (habenula) ;

Processus e cerebello ad testes.

VENTRICLES OF THE BRAIN.

The interior of the brain contains . five distinct cavities,
named the ventricles of the brain, situated as follows: Two lat-
eral ventricles (ventriculus lateralis), in the upper part, within
the substance of the hemispheres, the third ventricle (ventriculus
tertius) between the optic thalami at the base of the brain, the
fourth ventricle (ventriculus quartus) between the medulla
oblongata and the cerebellum, and the fifth ventricle within the
septum lucidum between the two lateral ventricles.

The ventricles intercommunicate — the two lateral ventricles
with the third by means of the foramen of Monro (foramen
interventriculars) , the third with the fourth ventricle by means
of the iter a tertio ad quartum ventriculum (aquceductus cere-
bri), and, in the fetus, with the fifth, and through the infundib-
ulum with the cavity of the pituitary body.

The lateral ventricle (ventrv ulus lateralis) is bounded
as follows : —

The roof, the corpus callosum; the floor is formed by the follow-
ing parts from before backward: corpus striatum, taenia semicircu-

THE NERVOUS SYSTEM.

309

laris. optic thalamus, choroid plexus, corpus fimbriatum and fornix;
internally, by tlie septum lucidum; externally, in front and behind by
the brain-substance. Each lateral ventricle presents three cornua — the
anterior cornu, posterior cornu, or digital comity, and the middle count.

—-Antlcorr
Nud cauef

ton

_— Post. cor.

Fig. 109.

The lateral ventricles and choroid plexus. St. term., stria termin-
als; That., thalamus; Hipp., hippocampus; Fimb., fimbria; .1;// cor
anterior cornu of lateral ventricle; Nucl. caud., nucleus caudatus; Col.
for., columns of the fornix; Yd. int., velum interpositum; Ch. pi.,
choroid plexus; Cat wo., calcar avis; Post, cor., posterior cornu of
lateral ventricle [Whitehead, after '/ray.)

The anterior cornu (cornu anterius) curves outward and
forward over the corpus striatum and into the anterior lobe.

The middle cornu (cornu inferius) passes into the middle
lobe, descending to the transverse fissure at the base of the brain.

310 HUMAN ANATOMY.

Its course is backward', outward, downward, forward and inward
(B., 0., D., F., I.).

The posterior cornu (cornu posterius) runs backward into
the posterior lobe, its course being backward, outward and
inward (B., 0., I.).

Parts of Lateral Ventricle — Corpus Callosum. — Described
above.

Septum Lucidum (septum p el 'lucid him) . — Forms the inter-
nal boundary of the lateral ventricle. It consists of two layers
of white and gray matter, and is attached above to the under
surface of the corpus callosum. below to the fornix, and ante-
riorly to the prolongation of the corpus callosum.

Between the laminae forming the septum is a narrow inter-
val— the fifth ventricle.

The Corpus Striatum. — Situated in the lateral ventricle,
its broad end directed forward into the fore part of the body
and anterior cornu of the ventricle, its narrow end directed
outward and backward, and separated from its fellow by the
thalami optici.

The intraventricular portion is called the caudate nucleus
(nucleus caudatus), the extraventricular, the lenticular nucleus
(nucleus lentiformis) , the two separated by the internal capsule.

The internal capsule (capsula interna) is a large layer of
white fibers, derived from the medulla and crura cerebri, sep-
arating the lenticular nucleus from the caudate nucleus ante-
riorly, and the lenticular nucleus from the optic thalamus
posteriorly.

The external capsule (capsula externa) is a small layer of
white fibers on the outer surface of the corpus striatum, between
the lenticular nucleus and the claustrum.

The claustrum is a convoluted layer of gray fibers between
the external capsule and the island of Reil.

The Tcenia Semicircular is, or Horny Band of Tarinus
stria terminalis). — A band of medullary substance in the fur-
row between the corpus striatum and the optic thalamus. Its
anterior portion descends with the anterior pillar of the fornix,
its posterior portion passes into the descending horn. Beneath
it is the vena corporis striati.

The choroid plexus (plexus chorioideus) , a vascular mem-
brane, occupying the margin of a fold of pia mater, known as
the velum interpositum (tela chorioidea superior; or, tela
chorioidea ventriculi tertii) . It runs across the floor of the
lateral ventricle, and communicates with its fellow of the op-

THE NERVOUS SYSTEM. 3-Q

polite side through the foramen of Monro. Posteriorly it

descends into the middle horn of the lateral ventricle.

The corpus iimbriatum (tcenia hippocampi or tamia fim-
bria), a narrow white hand behind the choroid plexus. It is
the lateral edge of the posterior pillar of the fornix.

The fornix, a lamella of white tibrous matter, beneath the
corpus eallosum, continuous with it posteriorly, but separated
from it anteriorly by the septum lucidum. It consists of two
symmetrical halves which join to form the body (corpus forni-
cis), each half having an anterior and posterior crus where they
do not join.

The anterior crura (columnar fornicis) curve down to the
base of the brain, where each crus spreads out and curves upon
itself to form the corpus albicans of that side. From this point
it passes to the corresponding optic thalamus.

The posterior crura (crura fornicis), at their commence-
ment, are joined to the under surface of the corpus eallosum.
They pass downward into the descending horns of the lateral
ventricles, being continuous with the concave borders of the
hippocampi majores.

The lateral edge of the posterior crus is called the corpus
fimbriatum.

The lyra is a series of lines, some transverse, others longi-
tudinal and oblique, on the under surface of the fornix, between
the diverging posterior crura.

Optic Thalamus (thalamus). — The thalami optici are two
large ganglionic masses, situated between the diverging portions
of the corpora striata. Each thalamus rests upon the eorre-
sponding crus cerebri.

The thalamus is bounded externally by the corpus striatum
and taenia semicircularis. and internally forms the lateral
boundary of the third ventricle.

Its upper surface is partly covered by the fornix. Its
under surface forms the roof of the descending horn of the
lateral ventricle.

It- posterior and inferior part exhibits two rounded emi-
nences, the external (corpus geniculatum hiferale) and internal
(corpus geniculatum mediate) geniculate bodies. Its anterior
extremity form- the posterior boundary of the foramen of
Monro, which foramen connects the two lateral ventricles with

the third.

Velum interpositiini (tela chorioidea ventriculi tertii), a
vascular membrane, reflected from the pia mater into the inte-
rior of the brain through the transverse fissure. It passes

312 HUMAN ANATOMY.

beneath the posterior border of the corpus callosum and fornix,
and above the corpora quadrigemina, the pineal gland and the
optic thalami. It forms the roof of the third ventricle (plexus
chorioidea ventriculi tertii). Its anterior extremity passes on
each side into the corresponding lateral ventricle, forming the
anterior extremity of the choroid plexus. The vascular fringes
of the velum interpositum projecting into the third ventricle
are called the choroid plexuses of the third ventricle.

It has two veins, the venae G-aleni (w. cerebri internee),
which run along its under surface and are formed by the veins
of the choroid plexuses and the vena? corporis striata (v. cor-
poris striata). The venge Galeni unite to form a single trunk
■ — vena magna Galeni — (v. cerebri magna) and empty into the
straight sinus.

The posterior cornu (cornu postering) of the lateral ven-
tricle runs into the substance of the posterior lobe. On the floor
of this horn is an eminence corresponding to a sulcus be-
tween two convolutions, and called the hippocampus minor
(calcar avis).

Between the posterior and middle (cornu inferius) horns is
another eminence — the eminentia collateralis, or pes accessorius.

The hippocampus major, or cornu ammonis (hippocam-
pus), a white eminence running the entire length of the floor
of the middle horn. This eminence is the doubled-in surface
of the gyrus fornicatus.

The lower extremity of the hippocampus major is called
the pes hippocampus (digitationes hippocampi).

The fascia dentata (fascia dentata hippocampi) , the gray
and serrated edge of the middle lobe. It is really external to
the cavity of the middle cornu.

The third ventricle (ventriciilus tertius) is a mere
fissure in the median line of the cerebrum, situated between
the optic thalami. It communicates with the lateral ventricle
by the foramen of Monro and with the fourth ventricle by the
iter a tertio ad quartum ventriculum. The cavity is crossed by
three commissures — the anterior commissure, a white, rounded
cord ; the middle or soft commissure, composed of gray matter ;
and the posterior commissure, a white band connecting the two
optic thalami. It is bounded by the following structures : —

The roof, by the velum interpositum, suspending the choroid plex-
uses of the third ventricle, and laterally the peduncles of the pineal
gland; floor, by the parts inclosing the interpeduncular space at the
base of the brain, viz. : the lamina cinerea, tuber einereum and infundib-
ulum, corpora albican tia and the posterior perforated space; laterally,

THE NERVOUS SYSTEM.

313

by the optic tlialami; m front, by the anterior commissure and anterior
crura of the fornix; behind, the posterior commissure and the iter a
tertio ad quartum ventricuhun.

The fourth vextricle (ventriculus quartus) is a dia-
mond-shaped cavity between the cerebellum behind and the
posterior surface of the medulla oblongata and pons in front.
It is inclosed behind by the pia mater, which contains an open-
ing for the exit and entrance of the subarachnoid fluid from
the subarachnoidean space of the brain and spinal cord, and
a vascular fold of pia mater — the choroid plexus. Its lower

Ch.ro i J

/Pineil Stria
?^L /Kntal R«tess of W Vent.

P'swA^, ■

I^IIS^

\ v?

\W SM/ \"Su-P Clorp <^M.aJ.

&-'t«ofR«f:P„f Space-

^••WjNV J

"**"""— AF-Wexty-

FIG. 110.

Mesial section of brain and brain stem. 1, anterior commissure;
2, middle commissure; 3, posterior commissure; 4, pituitary body;
IV, fourth ventricle.

angle is continuous with tbe central canal of the spinal cord;
and from the resemblance it bears to a writing-pen, the name
calamus scHptorvus is applied. It communicates in front with
the tbird ventricle by tbe iter a tertio ad quartum ventriculum.
It is bounded as follows: —

Tin- roof, valve of Vieussens (rchun mrihilhirr antrrius) and the
cerebellum, containing in front the foramen of Magendie [apertura
medialia ventricuM quorti), by which it communicates with the sub-
arachnoidean -pace: the floor, of rhomboidal outline, is traversed by a
vertical median fissure [sulcus longitudinalis fossce rhomboidece) con-
tinuous with the central canal of the cord. At the broadest part of the
ventricle are a series of transverse white lines or stria' medullares, de

314 HUMAN ANATOMY.

rived from the cochlear root and nucleus. These striae divide the floor
into two triangles, a superior and an inferior. The inferior triangle
presents a groove, the fovea inferior, whose diverging limbs below form
the so-called ala clnerea, which is a darker colored, triangular space.
There are in this locality several eminences, corresponding with the
nuclei of origin of the pneumogastric, glossopharyngeal and other
cranial nerves. The superior triangle presents an elevation, produced by
underlying white fibers, the fasiculus teres (colUculus facialis). Above
and external to the fasciculus teres is a depression, the fovea superior;
and just above this is a bluish area, the locus ccc-ruleus. This mottled
appearance is caused by the presence of the substantia ferruginea, a
peculiar pigment of some of the nerve cells and in them, one of the roots
of the trifacial nerve terminates. Anteriorly, the pons Varolii and
medulla oblongata; posteriorly, the cerebellum; laterally, the processus
e cerebello ad testes, the restiform bodies, and posterior pyramids of
the medulla.

Its lining membrane is continuous with that of the third
ventricle.

The fifth ventricle (cavtim septi pellucidi) is a narrow
fissure, formed within the two lamince of the septum lucidum,
being originally a part of the great longitudinal fissure. It is
bounded : —

Above, by the under surface of the corpus callosum;
Below, by the anterior part of the fornix;

Laterally, by the lateral ventricles, from which it is separated by
the septum lucidum.

It is not lined with epithelium.

The mesencephalon includes those portions of the brain
substance which connect the cerebrum, cerebellum and medulla
oblongata together, and comprises the following structures : —

Crura cerebri, before described (ante, p. 306).

The valve of Vieussens, or anterior medullary velum, is a
thin layer of white matter stretched between the processes e
cerebello ad testes, and forming the roof of the iter a tertio ad
quartum ventriculum. It presents an elevated ridge descend-
ing on its upper part from ' the corpora quadrigemina — the
frenulum.

Corpora or tubercula quadrigemina, or optic lobes, are four
spherical eminences, placed in pairs above the valve of Vieus-
sens, and behind the third ventricle, beneath the posterior bor-
der of the corpus callosum.

The two anterior are called the nates (colliculi superiores) ,
the two posterior the testes (colliculi inferiores). The brachia
anterior — (brachium quadrigeminum superius) and posterior —
brachium quadrigeminum inferius) are two white cords con-

THE NERVOUS SYSTEM. 315

iiecting them with the optic thalamus and beginning of the
optic Bracts.

The processus e cerebello ad testes connect them with the
cerebellum.

To the outer side of the optic lobes are two small masses
called the corpus geniculatum externum (corpus genie id atum
Jul crate) and internum (corpus geniculatum mediate).

The pineal gland, or epiphysis cerebri (corpus pineale), is
a >mall reddish, conical body, resting upon and between the
nates. It represents the rudiment of a median eye of certain
extinct lizards and amphibia (Spencer). It is attached to the
cerebrum by its two peduncles (habenula), and is held in posi-
tion by a fold of the pia mater. It contains a cavity, tilled with
a viscid fluid and secretory matter composed of phosphate and
carbonate of lime, phosphate of magnesia, ammonia, and a little
animal matter — -the acervulus cerebri.

THE INTERNAL STRUCTURE OF THE MEDULLA OBLONGATA.

The anterior and lateral pyramidal tracts of the cord are
continued into the medulla oblongata as the pyramids. The
lateral pyramidal tracts decussate in the lower part of the
medulla.

The anterior ground bundle is continued upward into the
medulla as the posterior longitudinal bundle. It lies behind
the pyramids in the medulla.

The sensory columns of the cord (Goll and Burdach) are
continued into the medulla oblongata and terminate in the
funiculus gracilis and euneatis. They increase in size and each
develops a nucleus: the clava and cuneate nucleus, respectively.
These fibers partly form the restiform bodies.

The decussation of the sensory fibers takes place at a higher
plane than that of the motor fibers. It is also called the decus-
sation of the fillet and it consists of the decussating fibers de-
rived from the clava and the cuneate nucleus. These fibers are
called deep arcuate fibers. After decussating the fibers are con-
tinued upward behind the pyramids, displacing backward the
posterior longitudinal bundle {fasciculus longitudinalis me-
dialis).

In the medulla on cross-section are seen the olivary bodies
(nucleus olivaris inferior), which contain the dentate nuclei.

The restiform bodies (corpus restiforme), ot inferior cere-
bellar peduncles, are formed by the direct cerebellar tract, the
superficial or externa] arcuate fibers (.fibres arcuatce external), the

316 HUMAN ANATOMY.

internal arcuate fibers (fibrce arcuatw internee), and the cere-
bello-olivary fibers.

The formatio reticularis is seen behind the pyramids and
the olivary bodies in the medulla oblongata. It is composed of
the deep arcuate fibers, fibers of Gowers's tract and the antero-
lateral ground-bundle.

The gray matter of the cord is continued into the. medulla.
The anterior horns are cut off and displaced by the decussation
of the lateral pyramidal tract and the posterior horns are dis-
placed outward by the increase in size of the posterior sensory
tracts. The latter are known as the nucleus of Rolando and are
capped by the substantia gelatinosa Rolandi.

The central canal is expanded into the fourth ventricle.
The gray matter forms nuclei for the cranial nerves in the floor
of the fourth ventricle.

THE INTERNAL STRUCTURE OF THE PONS VAROLII.

On cross-section the pons is seen to consist of a dorsal
tegmental part, and a ventral part, or crusta (pars basilaris
pontis).

The crusta is composed of transverse fibers (fibers from
the cerebellum to the pons and from the nucleus pontis to the
cerebellum), superficial (fibrce pontis superficiales) and middle,
which go to form the middle cerebellar peduncles; longitudinal
fibers, which belong to the pyramidal tracts, much scattered;
and gray matter, which here forms a nucleus called the nucleus
pontis.

The tegmentum of the pons contains a thick layer of gray
matter, which forms the floor of the fourth ventricle, and from
which cranial nerves take their origin; formatio reticularis,
which is the continuation upward of the same from' the medulla ;
the superior olivary nucleus (nucleus olivaris superior) ; the
posterior longitudinal bundle (fasciculus longitudinalis medi-
alis) ; the fillet (lemniscus) ; the superior cerebellar peduncle
(brachium conjunctivum) ; and the corpus trapezoides.

The fillet occupies a position between the crusta and teg-
mentum, and to differentiate it from a tract that makes its
appearance above the nucleus of the third nerve is called the
mesial fillet (lemniscus medialis).

The other tract is named the lateral fillet.

The lateral fillet (lemniscus lateralis) is composed of
longitudinal fibers which take origin from the- nucleus of the
eighth cranial nerve (cochlearis) of the same side, from that

THE NERVOUS SYSTEM.

;;i;

of the opposite side, and from the superior olive. They end
in the inferior quadrigeminal body, the internal geniculate body
and a few in the superior quadrigeminal body.

Mtitcoti

nuclcaurf.

J.lint.cap.

Ext. cap.
■Is/.

■MicL lent.
'■■Claus.
■—Pl.intcap.

.'Thai.
... C.j.m.
..T.nud.caud.

■Fimb
■-M pp.

..Post, con

ule; Ext. cap., external capsule; Tat, Island of Retl; Vucl Umt
Ducleus lentiformis; Clou., elaustrum; P. /. int. cap., posterior Hrnii
o* internal capsule; Hipp hippocampus; Post, cor., „ st ,•],,•', -, .
lateral ventricle-. (Whitehead, after Landois.) 'UOL,-"UI Lor,ul 01

The mesial fillet has been described. II lakes its origiu in
the medulla i'mm the euneate and gracile nuclei of the opposite

318 HUMAN ANATOMY.

side. Some of its fibers end in the superior quadrigeminal body,
but the remainder pass through the subthalamic tegmental,
region into the posterior part of the lateral nucleus of the optic
thalamus. Some end here, while some are continued through
the thalamus, enter the corona radiata, and pass to the posterior
central gyrus of the Eolandic region.

THE STRUCTURE OF THE CEREBELLUM.

On section the gray matter of the cerebellum is found to
occupy the cortex (substantia corticalis) ; to its arborescent
appearance the term arbor vitce has been applied.

The white matter, medullary body, of each hemisphere con-
tains a nucleus of gray matter: the corpus dentatum (nucleus
dentatus).

The middle peduncles connect the cerebellum with the pons.

The inferior peduncles, or restiform bodies, or crura ad
medullam (corpora restiformia) , connect the medulla and cord
with the cerebellum.

The superior peduncles (brachia conjunctiva cerebelli) con-
nect the cerebellum with the cerebral cortex. After decussating
below the corpora quadrigemina some of the fibers pass to the
opposite red nucleus (nucleus tegmenti) in the tegmentum of
the crura cerebri passing through the optic thalamus to end in
the Eolandic region, and others end in the optic thalamus.
Each superior peduncle contains both afferent and efferent
fibers.

The cerebellar cortex consists of two layers: an outer,
molecular layer, and an inner, granular layer. Between these
two layers is a single layer of large cells, the corpuscles of
Purkinje.

THE STRUCTURE OF THE MID-BRAIN.

The mid-brain consists of a dorsal part, the corpora quad-
rigemina, and a ventral part, the crura cerebri.

It is tunneled by the aqueduct of Sylvius, which connects
the fourth ventricle with the third ventricle.

The upper end of the crura cerebri is encircled by the optic
tract.

On section the crura cerebri show a ventral and lateral
portion, — the tegmentum, — and a dorsal portion, the lamina
quadrigemina. The ventral portion contains the substantia
nigra. The fissure of Sylvius is surrounded by gray matter,
from which the third and fourth cranial nerves take origin.

THE NERVOUS SYSTEM.

319

SENSORY MOTOR AREA

INTERNAL CAPSULE

FIRST TEMPORAL

CYBU8

QUADR10BM1NATB
BODIES^- '

INFERIOR PEDUNCLE-
OF CEREBELLUM,

SENSORY DECUSSATION
(DECUSSATION OF FILLET

JWJCLEUS CUNEATIS

OOWERSB TRACT

EIGHTH NERVE
NINTH NERVE
TENTH NERVE

NUCLEUS GRACILIS

POSTEROMEDIAN COLUMN,
POSTEROLATERAL COLUMN

■DIRECT CEREBEL1.AR TRACT

POSTERIOR NERVE ROOT

Wia. 112.
Diagram of sensory tracts from spinal cord to brain (original).

320 HUMAN ANATOMY.

The inferior or posterior quaclrigeminal bodies contain the
fibers of the lateral fillet posteriorly and the brachium laterally.

The superior or anterior quadrigeminal bodies consist of
four strata: stratum zonale, stratum cinereum, stratum opti-
cum and stratum lemnisci. The mesial and upper fillet in part
end in the latter, which also contains large nerve cells.

Some fibers from the occipital lobe and fibers from the
retina, conveyed by the superior brachium, end in the superior
quadrigeminal bodies.

The superior cerebellar peduncles have been described ; they
connect the cerebellum with the cerebral cortex.

The red nucleus (nucleus tegmenti) is found in the teg-
mentum. Some of the fibers of the superior cerebellar peduncles
end there.

The posterior longitudinal bundle lies in the tegmentum
and is the continuation upward of the tract of the same name
in the medulla and pons. It is connected with the nuclei of the
motor nerves of the muscles of the eyeball.

The lateral fillet is continued upward from the pons in the
tegmentum. Its connections with the superior olivary nuclei
and the nuclei of the eighth nerve have been described.

The mesial fillet likewise is continued upward from the
pons in the tegmentum of the crura. The course of the fibers
has been described.

The crusta of the crura contains the pyramidal fibers and
the corticopontine fibers.

THE STRUCTURE OF THE CEREBRUM.

On cross-section the cut brain surface shows an outer gray
cortex and the inner white matter and cavities (centrum ovale) ,
one to each hemisphere : the lateral ventricles. The white mat-
ter contains certain masses of gray matter : the optic thalami
and the corpora striata, which latter are on each side of the
brain divided into the caudate and lenticular nuclei by the
internal capsule. Between the optic thalamus and caudate
nucleus on the inside and the lenticular nucleus on the outside
passes the broad band of white fibers known as the internal cap-
sule (capsula interna). As it nears the cortex the fibers spread
out. To this is given the name corona radiata. Between the
external capsule (capsula externa) and the cortex of the island
of Eeil is seen a thin sheet of gray matter : the claustrum.

The white matter between the claustrum and the lenticular
nucleus is known as the external capsule. On horizontal section

THE NERVOUS SYSTEM.

321

CORTEX OF THE.
«8NS0RY MOTOR AREA

CORONA RADIATA

INTERNAL CAPSULE -V j

fOURTH NERVE

P0N8

•PINAL CORD

DECUSSATION OF PYRAMIDS

ANTERIOR PYRAMIDAL TRACT

ANTERIOR COMMISSURE

CAUDATE NUCLEUS
OPTIC THALAMUS

LENTICULAR NUCLEUS

THIRD NERVR

FIFTH NERVE

— SIXTH NERVH
SEVENTH NERVE

NINTH NERVB

TENTH NERVB

ELEVENTH NERVB

TWELFTH NERVB

LATERAL PYRAMIDAL TRACT

ANTERIOR NKRVK ROOT

Fig. 113.

Diagram of motor tracts from brain to spinal cord (original).

21

322 HUMAN ANATOMY.

of the brain the internal capsule is seen to be bent upon itself,
the interval between the optic thalamus and the caudate nucleus.
This bend is called the genu (genu capsulce internee). One-
third of the capsule lies in front of this bend, and is called the
anterior limb (pars frontalis capsulce internee) ; the portion
behind the genu is called the posterior limb (pars occipitalis
capsular internee).

The anterior limb contains (1) fibers that pass from the
optic thalamus to the lenticular and caudate nucleus, (2) fibers
that pass from the optic thalamus to the cortex of the frontal
lobe, and (3) fibers that pass from the cortex of the frontal
lobe to the nucleus pontis.

The posterior limb contains (1) a continuation upward of
a portion of the mesial fillet and the superior cerebellar pedun-
cles, (2) the pyramidal tracts or motor fibers from the Eolandic
area, (3) the fibers of the optic radiation (radiatio occipito-
thalamica), (4) the fibers of the auditory radiation (radiatio
temporothalamica) , and (5) the temporopontine tract.

The opposite sides of the brain are connected by the com-
missural fibers. Convolutions on the same side are connected
by association fibers. Projection fibers are those which unite
the cerebral cortex with nuclei in lower levels. They pass prin-
cipally through the corona radiata.

The cerebral cortex consists of five layers : the stratum
zonale, the layer of small pyramidal cells, the layer of large
pyramidal cells, the layer of polymorphous cells and a layer of
fusiform cell-bodies.

CRANIAL NERVES.

The cranial nerves (nervi cerebral es) consist of twelve
pairs, as follows : —

1. Olfactory, 8. Auditory (portio mollis),

2. Optic, 9. Glossopharyngeal,

3. Motores oculorum, 10. Pneumogastric (vagus, or par

4. Pathetici, vagum ) ,

5. Trifacial, 11. Spinal accessory,

6. Abducentes, 12. Hypoglossal.

7. Facial (portio dura),

1. Olfactory nerve (n. olfactorius) , special nerve of
smell. A number of nerves (20) arise from the olfactory bulb
or lobe of the brain. Superficial origin of the tract by roots :
internal from frontal lobe, middle or gray root from the olfac-
tory tubercle (trigonum olfactorium) between the other roots

THE NERVOUS SYSTEM.

323

of the tract, and external from the middle lobe; deep origin,
from gyrus fornicatus, uncinate gyrus of limbic lobe; course,
roots unite, pass forward, and form bulbus olfactorius (from
this the olfactory nerves are given off) ; exit, foramina of crib-
riform plate of ethmoid; distribution, by three groups to mu-

FiG. 114.

Scheme of the nuclei and root-fibers of the cranial nerves.
(Whitehead, after Edinger.)

( Schneider ian) membrane of nares, inner to septum nasi,
middle to roof of nasal fossa, outer to superior turbinated bone.
2. Optic nerve (n. opticus), special nerve of sight; super-
ficial origin, optic chiasms or commissure formed by union of
the optic tracts. The commissure and tracts contain intercere-

324

HUMAN ANATOMY.

bral fibers, the cerebroretinal fibers of the same side, and the
cerebroretinal fibers of opposite sides. Deep origin, the optic
tracts arise from optic thalamus, the upper corpora quadri-
gemina and corpora geniculati; course, diverge and pass for-

FiG. 115.

Base of brain and cranial nerves; 1, olfactory bulb; 2, optic
nerves; 4, tractusi opticus; 5, crus cerebri; 6, third pair of nerves;
7, fourth pair of nerves; 8, fifth pair of nerves; 9, sixth pair of nerves;
10, pyramid; 11, olivary body; 22, pons Varolii; 24, seventh and eighth
pairs of nerves; 25, ninth, tenth and eleventh pairs of nerves; 26,
twelfth pair of nerves; 27, cerebellum.

ward; exit, optic foramen; distribution, to ganglion cells in the
retina.

3. Motor oculi (n. oculomotorius) , motor nerve; super-
ficial origin, inner surface of crus cerebri ; deep origin, from the

Forehtad ttud Stalp

'ouppa-Mytlidaad^arrh^ad

la anJ Itn-krymiil >w

[/al'tr'ilil

PIG. 116.

Optic, oculomotor, trochlear, and trifacial nerves,

THE NERVOUS SYSTEM. 325

oculomotor nucleus in floor of aqueduct of Sylvius; course, from
inner side of eras cerebri passes forward, descends along exter-
nal wall of cavernous sinus; exit, sphenoidal fissure between
two heads of external rectus muscle; distribution, by superior
and inferior divisions, to all the ocular muscles (including the
iris) except the external rectus and superior oblique.

4. Trochlear (to, trochlearis — pathetic), motor nerve;
superficial origin, from valve of Yieussens, on outer side of crus
cerebri; deep origin, from floor of aqueduct of Sylvius; course,
outer side of crus cerebri, through outer wall of cavernous sinus ;
exit, sphenoidal fissure; distribution, to superior oblique muscle.

5. Trifacial, or Trigeminus (to. trigeminus), common
sensation, taste and motion ; superficial origin, by two roots,
like a spinal nerve, from the side of the pons Varolii; deep
origin, the motor root, from (1) a nucleus in the floor of the
aqueduct of Sylvius (descending motor root), and (2) from a
nucleus in the pons (these join to form the motor root) ; the
sensory root ends in two terminal nuclei — (1) the sensory
nucleus of the fifth nerve in the pons, and (2) the substantia
gelatinosa Rolandi in the pons, medulla and the spinal cord as
far down as the second cervical nerve; course, passes forward
to apex of petrous portion of temporal bone, where the sensory
root enters Gasserian ganglion, the motor passing beneath, and
later joins a branch of the ganglion. It divides into three
branches — ophthalmic, superior maxillary and inferior maxil-
lary; exit, ophthalmic by sphenoidal fissure, superior maxillary
by foramen rotundum, inferior maxillary by foramen ovale.

Ophthalmic nerve (n. ophthalmicus), entirely sensory, sup-
plies lachrymal gland, upper eyelid, skin and muscles of fore-
head, eyebrow, aose, eyeball (ciliary muscle, iris, etc.), mucous
membrane of eyelids and nose and the ciliary ganglion.

Its branches are: —

Lachrymal (n. lacrimalis) ;
Frontal ( n. frontalis) ;
Naaal (n. nasociliaris) .

Superior maxillary nerve (to. maxillaris), entirely sensory
also; supplies sensation to upper jaw, teeth, hard and soft
palates, tonsils, gums, antrum of Eighmore, muscles, skin and
mucous membrane of lower eyelid, muscles and skin of cheeks
and upper lip, and mucous membrane of floor of nares.

326

HUMAN ANATOMY.

Middle superior den-
tal ( ramus alveo-
la/ris superior me-
dius ) ,

Anterior superior den-
tal (ramus alveo-
laris superior ante-
riores ) ,

Palpebral ( rami pal-
pebrales inferiores) ,

Nasal ( rami nasales
interni) ,

Labial (rami labiates
superiores ) .

Its branches are :-

Meningeal ( n. menin-
geus medius) ,

Orbital ( n. zygoma-
ticus ) ,

Spheno-palatine ( n.
sphenopalatine ) ,

Posterior superior den-
tal (rami alveolcures
superiores posteri-
or es ) ,

Inferior maxillary nerve (n. mandibularis) consists of two
portions: anterior or motor, and posterior or sensory, having
a threefold function, because one of its branches, the lingual, is
joined by the chorda tympani nerve (given off from the facial
nerve), which conveys gustatory fibers to the anterior two-thirds
of the tongue. It supplies motion to all the muscles of masti-
cation (except to buccinator), anterior belly of digastric and
mylohyoideus ; sensation to skin of ear, lower part of face, lower
lip and tongue/ Previous to its division, the primary trunk
gives off the recurrent (n. spinosus) and the internal pterygoid
(n. pterygoideus internus). Immediately below the base of the
skull it divides into an anterior and a posterior portion. Its
branches- are : —

Posterior Portion.

Auriculotemporal (n. auriculotem-
poral ) ,

Inferior dental (n. alveolaris in-
ferior ) ,

Lingual ( n. lingualis ) .

Anterior Portion.
Masseteric (n. mussetericus) ,
Deep temporal (nn. temporales

profundi ) ( 2 ) ,
Buccal (n. buccinatorius) ,
Pterygoid (n. pterygoideus exter-

nus ) ,

The fifth nerve has four ganglia connected with it: —

(a) Ophthalmic, or lenticular (ganglion ciliare) ■

(b) Sphenopalatine, or Meckel's (ganglion sphenopalatinum) ;

(c) Otic, or Arnold's (ganglion oticum) ;

(d) Submaxillary (vide Sympathetic System) (ganglion sub-
maxillar e) .

6. Abducens (n. abducens), motor; superficial origin,
pyramidal body and pons Varolii; deep origin, floor of fourth
ventricle; course, passes forward in cavernous sinus; exit, sphe-
noidal fissure; distribution, to external rectus muscle.

7. Facial (n. facialis), motor nerve; superficial origin,
lateral tract of medulla and pons Varolii; deep origin, from a
nucleus in the pons, deeply placed, from which the fibers ascend

THE NERVOUS SYSTEM.

337

k §.■§ &? ?s

ill

Fig. 117.

328

HUMAN ANATOMY.

close to the floor of the fourth ventricle, where they form the
eminentia teres, arch over the nucleus of the sixth nerve, and
then emerge (this nerve carries some sensory fibers, probably
gustatory fibers from the tongue, through the chorda tympani
nerve to the pars intermedia [n. intermedins], near the nucleus
of the ninth nerve) ; course, forward and outward, through in-
ternal auditory meatus, aqueductus Fallopii and inner wall of
tympanum; exit, stylomastoid foramen; distribution, to muscles
of expression, buccinator, and platysma, posterior belly of digas-
tric, stylohyoid attrahens and retrahens aurem muscles, to
laxator tympani and stapedius through tympanic branch, dorsal
surface of tongue through chorda tympani, and levator palati,
and azygos uvulae muscles through Vidian. In its course
through the temporal bone it communicates with many impor-
tant nerves; in the internal auditory meatus, with auditory
(portio mollis) ; in aqueductus Fallopii, with otic ganglion, by
the small petrosal; Meckel's ganglion, by the large petrosal
nerve ; the sympathetic of the great meningeal, by the external
petrosal nerve; and at its exit from the stylomastoid foramen,
with the glossopharyngeal, pneumogastric, auriculotemporal,
auricularis magnus and the carotid plexus. Its branches are : —

On the Face.

{Temporal (rami temporales) .
Malar (rami zygomatics).
Infraorbital (rami buccales).

In Aqueductus
Fallopii.

Tympanic
( n. stapedius ) .
Chorda tympani.

^

r Buccal (rami buccales).

r, . . . , j Supramaxillary (ramus mar-
Cervicoiacial, < £• 7- •'-,-, v 7 >

' ', gnnahs mandioukc) .

I Inframaxillary (ramus colli).

Posterior auricular,

Stylohyoid (ramus stylohyoideus) ,
Digastric (ramus digastricus) .

8. Auditory (n. acusticus), special nerve of hearing, con-
sists of two portions — (1) cochlear, or auditory portion, and
(2) vestibular, or fibers whose function is to localize position.

The former pass from the cochlea to the (1) accessory
auditory nucleus in the medulla, and (2) to the lateral acoustic
tubercle in the medulla. These fibers, by means of the lateral
fillet, communicate with the inferior corpora quadrigemina.

The vestibular fibers (fibrce vestibularis) pass from the
vestibule to the external and internal dorsal nuclei in the floor
of the fourth ventricle, and by the sensory decussation to the
nucleus cuneatus.

THE NERVOUS SYSTEM.

329

Fiu. US.

330 HUMAN ANATOMY.

Superficial origin, from groove between olivary and resti-
form bodies; course, winds around restiform body, and passes
forward to internal auditory meatus, with the facial; distribu-
tion, to internal ear by two branches : —

Vestibular, and Cochlear {vide Ear, p. 370).

9. Glossopharyngeal (n. glossopharyngeus) , or ninth,
nerve of motion, common sensation, and taste ; superficial origin,
from medulla oblongata, between olivary and restiform bodies ;
deep origin^, from motor and sensory gray nuclei in floor of
fourth ventricle; course, passes outward across flocculus; exit,
jugular foramen, in separate sheath, in front of pneumogastric
and spinal accessory, having two gangliform enlargements upon
it — jugular, and the petrous or ganglion of Andersch; dis-
tribution, to mucous membrane of fauces, tonsil, pharynx and
middle ear, muscles of the pharynx, and special sense of taste
to the base and sides of the tongue. Its branches are: —

Tympanic ( Jacobson's ) , (n. tym- Pharyngeal branches (rami phar-

pamcus ) , yngei ) ,

Carotid branches (n. caroticotym- Tonsillar branches (rami tonsil-

panicus superior et n. carotico- lares),

tympanicus inferior ) , Lingual branches ( rami linguales ) .
Muscular branches (ramus stylo-

pharyngeus ) ,

10. Pneumogastric, vagus, or par vagum (n. vagus),
tenth nerve, motor and sensory; superficial origin, from groove
between olivary and restiform bodies by a dozen filaments ; deep
origin, from nuclei in floor of fourth ventricle; course, passes
outward across the flocculus; exit, jugular foramen in a com-
mon sheath with the spinal accessory nerve; distribution (not
definitely known), motor nerve to the organs of respiration and
voice, and a motor and sensory nerve to heart, esophagus,
pharynx and stomach. It branches are : —

Meningeal (ramus meningeus) , Cervical cardiac (rami carcliaci

Auricular (Arnold's) (ramus superior es) ,

auricularis), Thoracic cardiac (rami cardiaci

Pharyngeal (ramus pharyngcus) , inferior -es) ,

Superior laryngeal, Anterior pulmonary,

Recurrent laryngeal (n. laryngeus Posterior pulmonary,

inferior), Esophageal (rami esophagei) ,

Gastric (rami gastrici) .

It also communicates with the left hepatic sympathetic
plexus.

THE NERVOUS SYSTEM. 331

11. Spiral accessory (n. accessorvus) , eleventh, motor
nerve; superficial origin, from lateral tract of medulla and
spinal cord as low as sixth cervical nerve; deep origin, spinal
portion from anterior horn of gray matter; accessory portion
from gray nucleus in floor of fourth ventricle; course, the spinal
portion enters the skull through the foramen magnum, and joins
the accessory portion in the jugular foramen ; exit, jugular fora-
men in sheath with the pneumogastric ; distribution, to sterno-
cleidomastoid and trapezius muscles, communicating with the
cervical plexus and pharyngeal and laryngeal branches of pneu-
mogastric.

12. Hypoglossal (n. lnjpoglossus) , or twelfth nerve, motor
nerve of tongue; superfii ial origin, from groove between olivary
and pyramidal bodies by about a dozen filaments; deep origin,
from gray nucleus at lowest part of floor of fourth ventricle;
exit, anterior condyloid foramen; distribution, to the omohyoid
(both bellies), sternohyoid, sternothyroid, thyrohyoid, and mus-
cles of the tongue — styloglossus, hyoglossus, geniohyoid, genio-
hvoglossus, communicating with the pneumogastric, sympa-
thetic, first and second cervical and gustatory nerves. Its
branches are: —

Descendens hypoglossi (ramus descendens) , Muscular,

Thyrohyoid '{ramus thyreohyoid-eus) , Meningeal.

Membranes of the Cord.< — The membranes of the spinal
cord are three — the dura mater, arachnoid and pia mater.

Dura mater (dura mater spinalis) is> a loose fibrous sheath,
continuous with the dura of the brain, and from which it differs
in not inclosing the venous sinuses, not dipping into the fissures
of the cord, and not being adherent to the bony canal. From
the latter it is separated by the venous plexuses (plexus venosi
vertebrates interni) and some connective tissue.

It extends the whole length of the canal, from the foramen
magnum (to which it is attached) to the top of the sacrum.

Arachnoid (araclmoidea spinalis) is a delicate serous sac,
continuous above with the cerebral arachnoid, inclosing the pia
mater, from which it is separated by an interval — the sub-
arachnoidean space (cavum subarachnoideale) . It is filled with
the cerebrospinal fluid (liquor cerebrosjnnalis). The outer sur-
face of the arachnoid is in contact with the dura, the space
between them being called the subdural space (cavum subdurale).

Pia mater (pia mater sjnnalis) is a fibrous membrane,
closely adhering to the cord and forming its neurilemma. Over
the anterior median fissure, if is strengthened by a fibrous hand

332 HUMAN ANATOMY.

— the linea splendens — .and laterally has the lig amentum den-
ticulatum. It terminates below the cord as the plum terminate
— a slender filament.

THE SPINAL CORD.

The spinal cord {medulla spinalis) is the elongated portion
of the cerebrospinal axis contained in the spinal canal. Its
length is about sixteen to eighteen inches, extending from the
medulla above to the lower border of the first lumbar vertebra
below, where it terminates in the cauda equina by a slender pro-
longation of gray substance, called the conus medullaris.

It presents two enlargements, the upper or cervical (intu-
mescentia cervicalis), extending from the third cervical to the
second dorsal vertebra, and the lower or lumbar (intumescentia
lumbalis), about the position of the second or third dorsal
vertebra. It is divided into two lateral halves by the anterior
(fissura mediana anterior) and posterior median fissures (sulcus
medianus posterior), united in center by the commissure. The
lateral portions are subdivided by anterolateral (sulcus lateralis
anterior) and posterolateral fissures (sulcus lateralis posterior)
into anterior lateral and posterior lateral columns, and poste-
riorly a narrow fissure separates the posterior median column
from the posterior median fissure. The gray substance occupies
the center of the cord, and is arranged into two crescentic
masses connected together by the gray commissure (commissura
grisea). The posterior horn (columna grisea posterior) forms
the apex cornu (apex columna grisea posterior), from which
arises the posterior root of the spinal nerves. The anterior horn
(columna grisea anterior) is thick and short, and affords origin
to the anterior root of the nerve. The gray commissure contains
throughout its whole length a minute canal — the central canal,
or ventricle of the cord (canalis centralis), continuous above
with the fourth ventricle.

SPINAL NER.VES.

The spinal nerves (nervi spinales) consist of thirty-one
pairs, arranged in the following order: cervical, eight pairs;
dorsal, twelve pairs; lumbar, five pairs; sacral, five pairs;
coccygeal, one pair.

Each of the spinal nerves arises by two roots, an anterior
(radix anterior) or motor and a posterior (radix posterior) or
sensory. The fibers of the anterior root arise from the antero-
lateral columns, originating deeply in the gray mattei of the

THE NERVOUS SYSTEM.

333

Fig. 119.

334 HUMAN ANATOMY.

cord. The posterior roots arise at the posterolateral fissure, also
originating deeply in the gray matter of the cord. The pos-
terior roots have each a ganglion (ganglia spinales) developed
upon it — except sometimes the first cervical. These roots unite
and the nerve then subdivides into two branches, both having
motor and sensory fibers. The posterior branches are small;
they supply the skin and muscles of the back.

The anterior branches supply the neck, front and sides of
the trunk, and the extremities.

Cervical Plexus (plexus cervicalis). — The cervical plexus
is formed by the anterior divisions of the first to the fourth
cervical nerves. It is covered by the sternomastoid muscle, and

Fig. 120.

Section of spinal cord and membranes: 1, dura mater; 2, arach-
noid membrane; 3, ganglion on posterior root; 4, anterior root of
spinal nerve; 5, 5, subarachnoid space; 6, posterior branch of spinal
nerve; 7, anterior branch of spinal nerve.

rests upon the scalenus medius and levator anguli scapulae mus-
cle. It gives off: —

Superficial.
Superficialis colli (n. cutaneus Occipitalis minor (n. occipitalis

colli), minor),

Auricularis magnus (n. auricu- Supraclavicular (nn. supi'aclavic-

laris magnus), ulares) .

Deep.
Deep (Internal Series) Deep (External Series)

Communicating, Communicating,

Muscular, Muscular.

Phrenic ( n. phrenicus ) ,
Communicantes hypoglossi,

The phrenic nerve,, or internal respiratory of Bell, is de-
rived from the third and fourth cervical nerves, with a branch
from the fifth. It descends into the chest between the sub-
clavian artery and vein, between the pericardium and the
pleura, to the diaphragm, to Avhich it is distributed (rami

THE NERVOUS SYSTEM.

335

Fig. 121.

336 HUMAN ANATOMY.

phrenicoab dominates) . The course of the two nerves differs in
the thorax (vide Mediastinum).

The beachial plexus (plexus brachialis) is formed by
the anterior branches of the four lower cervical and the hrst
upper dorsal nerves — the fifth, sixth and seventh forming one
cord, and the eighth cervical and first dorsal another cord.
Below the line of the clavicle (pars infracldvicularis) both
these trunks divide, the adjacent cords of the two upper uniting
to form the posterior (fasciculus posterior) , and the remaining
cords forming the outer (fasciculus lateralis) and inner (fascic-
ulus medius) cords respectively, receiving their names from
their relative position to the subclavian artery. Each of these
cords again bifurcates, the adjacent divisions at the outer end-
ing of the cords, uniting over the artery to form the median
nerve, the other divisions forming the musculocutaneous, ulnar,
circumflex and musculospiral, the two latter being the divisions
of the posterior cord. Its branches are : —

Above the clavicle (pars supraclavicularis) : —

Communicating, arises from the fifth cervical, and passes
to the phrenic;

Muscular (rami muscular es), supply the scaleni, rhom-
boidii, longus colli and subclavius;

Posterior thoracic (n. thoracalis longus), long thoracic, or
external respiratory of Bell, arises by five roots from the fifth
to seventh cervical nerves, which unite within the scalenus
medius muscle and descend to supply the serratus magnus;

Suprascapular (n. suprascapularis) , passes beneath the tra-
pezius, through the suprascapular notch, to supply the shoulder-
joint and supraspinatus muscle.

Below the clavicle (pars subclavicularis) : —

The anterior thoracic nerves (nn. thoracales anteriores) are
two in number : an external branch from the outer cord and an
internal from the inner cord. The former supplies the pec-
toralis major and the latter the pectoralis minor, and sending
branches to the pectoralis major.

The subscapular nerves (nn. subscapulares) are three in
number. The upper subscapular supplies the subscapular mus-
cle, the lower subscapular nerve supplies the teres major and
subscapularis, the middle or long subscapular supplies the latis-
simus clorsi.

The circumflex nerve (n. axillaris) accompanies the pos-
terior circumflex artery, passing through the space formed be-
tween the teres major, teres minor and long head of the triceps
to supply the shoulder joint and skin over the shoulder and the

THE NERVOUS SYSTEM. 337

neighboring muscles. It gives off two branches, an upper and
a lower branch.

The musculocutaneous nerve (n. musculocutaneus) pierces
the coracobrachial muscle and descends the arm to supply the
brachialis anticus. biceps, coracobrachial and the skin of the
forearm. At the outer border of the tendon of the biceps, above
the elbow, it becomes superficial and divides into two brandies
— the anterior descending the radial side of the forearm to the
wrist and supplying the skin of that part, the posterior branch
descending the back part of the radial side of the forearm to
the wrist. It supplies skin of lower third of forearm.

The internal cutaneous nerve (n. cvianeus antibracliii me-
dialis) descends the inner side of the arm together with the
basilic vein to about its middle, where it becomes cutaneous,
supplying the skin of this region. It has an anterior and a
posterior branch.

The lesser internal cutaneous nerve of Wrisberg (n. cuta-
neus brachii medialis) is derived from the inner cord, and
receives filaments from the eighth cervical, first dorsal and the
intercostohumeral nerve, and is distributed to the skin on the
inner side of the arm.

The median nerve (n. medianus), formed by a root from
the outer and inner cord of the brachial plexus, descends the
arm, crossing the brachial artery from its outer to its inner side
at the bend of the elbow. Its branches are : — -

Muscular (rami muscular es) branches, supply all the superficial
anterior muscles except the flexor carpi ulnaris;

Anterior interosseous (n. intcrosseus antibracMi volaris), supplies
all the 3eep anterior muscles except the inner half of the flexor pro-
fundus digiforum;

Palmar cutaneous (ramus cutan&us palmaris n. mediarri), crosses
above the annular ligament, divides into two branches to supply tha
ball <»f the thumb and the palmar surface of the hand;

Branches 10 the muscles of the thumb (r<nni musculares) , sup-
ply the opponens, outer head of the small flexor, and the abductor;

Digital branches (mi. digitales volares proprii), supply both sides
of the thumb, index and middle and the radial side of the ring finger.

The ulnar nerve (n. ulnaris) descends the inner side of the
axillary artery to the middle of the arm, where it crosses the
internal head of the triceps, and accompanies the inferior pro-
funda artery to the elbow, where it passes between the heads of
the flexor carpi ulnaris. Its branches are, in the forearm: —

Irticular (elbow), supplies tin1 elbow joint;

Muscular [rami musculares), to inner half of the deep flexors and
flexor carpi ulnaris;

22

338 HUMAN ANATOMY.

Cutaneous (ramus cutaneus palmaris), supplies the skin of the
palm;

Dorsal cutaneous (ramus dor salts manus) , supplies both sides of
the little finger and the ulnar side of the ring finger;

Articular (wrist), supply the wrist joint.

In the hand : —

Superficial palmar (ramus superficialis n. ulnaris) , supplies the
skin of both sides of the little and the ulnar side of the ring finger and
palmaris brevis muscle;

Deep palmar (ramus profundus n. uhvaris) , supplies the inter-
ossei, lumbricales, adductor pollici, and inner head of flexor brevis
pollicis.

The musculospiral nerve (n. radial is) , derived from the
posterior cord of the brachial plexus, descends the arm in front
of the teres major and latissimus dorsi muscle, accompanies the
superior profunda artery through the musculospiral groove to
the outer side of the elbow, between the supinator longus and
the brachialis anticus, where it divides into the radial and pos-
terior interosseous nerves. Its branches are : —

Muscular (rami musculmes n. radialis), supply the supinator lon-
gus, external carpi radialis longior, triceps, anconeus and brachialis
anticus ;

Radial (ramus superficialis n. radialis), descends in the course of
the radial artery to three inches above the -wrist, where it becomes super-
ficial, and supplies the adjoining sides of the thumb and index, index
and middle, middle and ring fingers.

Cutaneous, supply the outer side of the arm, elbow, and radial side
of forearm and wrist;

Posterior interosseous (ramus profundus n. radialis), passes
through the supinator brevis muscle, and supplies, as it descends, all
the posterior brachial and radial muscles, except those supplied by the
muscular branches of the ulnar. It has a ganglion upon it.

Dorsal Nerves. — The posterior divisions of the dorsal
nerves (nn. thoracales) subdivide into the external and internal
branches to supply the muscles of the skin of the back. The
anterior [rami anterior es) divisions of the dorsal nerves, inter-
costal nerves (nn. intercostales) , twelve in number, supply the
walls of the abdomen and thorax. They are divided into two
sets — the upper six, distributed for the most part to the walls
of the chest, and the lower six, to the walls of the chest and
abdomen. The upper six dorsal nerves run between' the two
sets of the intercostal muscles, accompanied by the intercostal
vessels, to supply the skin over the front of the chest and the
mammas. Their branches are : —

Lateral cutaneous (rami cutanei laterales pectorales) , divide into
two branches, anterior and posterior;

Toouta-partoffivutofl'htgli
Tofroat ol~Th,.yIi.\

To'skinoreruuurMklf.

Pig. 1X2.
Lumbar plexus aud brancbe

THE NERVOUS SYSTEM. 339

Anterior branches (rami unto ions) , to the skin of the chest and
mamma? principally ;

Posterior branches [rami posteriores) , to the skin over the scap-
ular and lower dorsal regions.

The first intercostal nerve (u. intercostalis) is not dis-
tributed to the skin, but crosses the axilla under the name of
the intercostohumeral nerve; it joins the brachial plexus. The
lower six dorsal nerves have received the name of lower, or
abdominal intercostal nerves, from their distribution. The last
dorsal one is of large size, and gives off a branch, the dorsilum-
bar nerve, to join the lumbar plexus.

Lumbab Xerves (tin. lumhales). — The posterior (rami
posteriores) divisions of the lumbar nerves have the same dis-
tribution as the other spinal nerves. The anterior divisions of
the upper four lumbar nerves unite to form the lumbar plexus.
The fifth, with a branch from the fourth, joins the sacral nerves
to form the lumbosacral cord.

The lumbar plexus (plexus lumbdlis) is formed by the
communicating loops from the anterior branches of the first four
lumbar nerves and a branch from the last dorsal.

Its branches are: —

1. Iliohypogastric (n. iliohypogastric us) , divides into two
branches : —

(a) Iliac branch {ramus cutancus lateralis), supplies the skin of
the gluteal region and the oblique muscles of the abdomen;

(6) Hypogastric braneli (ramus cutancus anterior), supplies the
skin of the hypogastric region and the oblique muscles.

2. Ilioinguinal (a. ilioinguinalis) , supplies the skin of the
inner and upper part of the thigh, the scrotum, and labium (in
Female).

3. Genitocrural (//. genitofemoralis) , passes through the
psoas muscle and divides into two branches: —

"1 Genital braneli (//. s/>< riniit icus extern us I . follows the sper-
matic cord to supply the cremaster muscle; in female] supplies round
ligamen! ;

(0) Crural branch in. I umboi ngui nalis ) , descends m the sheath
of the femoral vessels to supply the skin in front of the thigh.

1. External cutaneous (n. cutaneus femoris lateralis)
emerges below the anterior superior spine of ilium and divides
into: —

('/i Anterior braneli, i<> skin of outer and fronl aspect of thigh;
(6) Posterior branch, to skin of outer and back aspect of thigh.

340 HUMAN ANATOMY.

5. Obturator (n. obturatorius) , follows the brim and outer
wall of pelvis to foramen (obturator), which it pierces to enter
thigh.

(a) Anterior branch (ramus anterior), supplies the femoral
artery;

(b) Posterior branch (ram-us posterior), supplies the adductor
muscles;

(c) Articular branch, supplies the synovial membrane of knee
joint.

6. Accessory obturator (n. obturatorius accessorius) , sends
a branch to the hip joint and one to join the anterior branch
of the obturator nerve.

7. Anterior crural (n. femoralis), the largest branch of the
lumbar plexus, descends through the psoas muscle, beneath
Poupart's ligament, into the thigh, where it divides into an
anterior or cutaneous branch, and a posterior or muscular
branch. It supplies all the muscles and the front of the thigh,
excepting the tensor vagina? femoris, gives branches to the knee,
and supplies the skin of the inner side in front of the thigh,
and to the leg and foot. Its branches from the anterior
division are : —

(a) Middle cutaneous, to sartorius muscle and skin of front of
thigh ;

( b ) Internal cutaneous, supplies the skin in the inner aspect of
the leg;

(c) Long saphenous (n. saphenus) , or internal saphenous, passes
through Hunter's canal, accompanies the internal saphenous vein, to
supply the skin of the inner side of the foot.

From the posterior division : —

(a) Muscular, to the muscles of the anterior and lateral aspects
of the thigh;

(b) Auricular, to the knee joint.

The sacral nerves (nn. sacrales), five in number, divide
into anterior and posterior nerves. The upper four sacral
nerves, with the fifth lumbar, and a filament from the fourth,
(the latter two forming the lumbosacral cord) together make the
sacral plexus (plexus sacraUs). It lies upon the anterior sur-
face of the pyriformis muscle, and is separated from the viscera,
the sciatic and pudic branches of the internal iliac artery by
the pelvic fascia. Its branches are: —

1. Muscular (rami muscular es) , supply the obturators,
gemelli, quadratus femoris and pyriformis.

2. Superior gluteal (n. glutozus superior), supplies the
glutei muscles and tensor vaginas femoris.

THE NERVOUS SYSTEM. 341

3. Pudic (n. pudendus), accompanies the internal pudic
artery, passing out of the great sacrosciatic foramen, around
the spine of the ischium to re-enter the lesser sacrosciatic fora-
men. It gives off: —

(a) Inferior hemorrhoidal (n. hcemorrhoidalis inferior), supplies
the skin of the anus ;

(b) Perineal (n. perinei) , follows the course of the superficial
perineal artery to supply the perineal structures generally;

(c) Dorsal nerve of the penis (to. dorsalis penis), follows the
course of the corresponding artery to supply the skin of the glans,
prepuce and penis generally.

4. Small sciatic (n. cutaneus femoris posterior), supplies
the skin of the thigh, leg, perineum and the gluteus maximus
muscle. Its branches are: —

(a) Inferior gluteal, to the gluteus maximus;

(b) Internal cutaneous branches (toto. cluniuin inferiores laterales),
to the skin of the inner and upper part of the thigh, and one branch,
the inferior pudendal, supplies the skin of the scrotum in the male and
labium in the female;

(c) Ascending cutaneous branches supply the skin over the gluteus
maximus.

5. The great sciatic nerve (n. isckiadicus) , the largest in
the body, passes out of the great sacrosciatic foramen, and
descends between the tuberosity of the ischium and the great
trochanter to the lower third of the thigh, where it divides into
the internal and external popliteal. It gives off: —

(a) Muscular branches (rami musculares) , to the muscles on the
inner and posterior aspect of the thigh ;

(b) Articular branches, to the hip joint.

The internal popliteal (n. tibialis), descends through the
popliteal space to the arch of the soleus muscle, where it
becomes the posterior tibial. It gives off: —

(a) Articular branches (rami articulares) , to knee joint;
(6) Muscular branches (rami musculares), to the muscles on the
posterior aspect of the leg;

(c) Kxicrnal, or short saphenous nerve (n. suraUs), passes be-
tween the two heads of the gastrocnemius muscle, and descends the leg.
receiving the comnxunicans peronei branch from the external popliteal,
around the outer malleolus to supply the skin of the outer side of the
foot.

The 'posterior tibial nerve descends the leg in company with
the posterior tioial vessels to below Hie inner ankle, where it
divides into the external and internal plantar nerves. It gives

oil':—

342 HUMAN ANATOMY.

1. Muscular branches (rami musculares) , to the deep muscles of
the calf;

2. Internal cancaneal (rami aalctmei mediates), supplies the skin
on the inner side of the sole and heel;

3. Articular branch, to ankle joint.

The internal plantar (n. plantaris medialis) accompanies
the corresponding artery to the inner side of the foot and gives
off:—

1. Cutaneous branches;

2. Muscular branches;

3. Articular branches;

4. Four digital branches, supplying both sides of the first three toes
and the inner side of the fourth.

The external plantar (n. plantaris lateralis) supplies by a
superficial branch the outer side of the fourth and both sides
of the fifth toes, and gives off a deep, or muscular, branch.

The external popliteal or peroneal nerve (n. peronceus com-
munis) descends to the inner side of the biceps tendon, pierces
the peroneus longus about one inch below the head, and divides
into the anterior tibial and musculocutaneous. It gives off: —

1. Articular branches (rami articulares) , to knee joint;

2. Cutaneous branchesi (n. cutaneus surce lateralis), one of which
is the communicans peronei (ramus anastomoticus peronceus or com-
municans fibularis) , which joins the short saphenous.

The anterior tibial (n. perona?us profundus) accompanies
the corresponding artery on its outer side to the ankle, where,
after aivingr off an articular branch, it divides into: —

1. External or tarsal branch, to the tarsal and metatarsal joints,
and

2. Internal, to the dorsal adjoining sides of the great and second
toes.

The musculocutaneous (n. peronceus superficialis) gives
off:—

1. Internal branches, (n. cutaneus dorsaUs medialis), supply skin
of inner side of foot and ankle, and inner side of great toe;

2. External branch (n. cutaneus dorsalis intermedium) , to the dor-
sum of the adjacent sides of the second, third, fourth and fifth toes.

/*

Fig. 123.
Sacral plexus and branches.

s

First

cervical <
nerve,

Second
cervical
nerve

Third

cervical -

nerve,

Fourth

to
eighth ■{
cervical
nerves,

THE XERVOIS SYSTEM. 343

Table of the Spinal Nerves.

Complexus, recti and obliqui muscles.

Posterior

d his ion

1 suboccipital)

Anterior

division

(occipital),

Posterior
division,

Anterior
division,

Posterior
divison,

Anterior
divison.

Posterior
divisions,

Unites with the second cervical nerve,
and supplies the anterior recti and
rectus lateralis muscles.

External "> Splenitis, complexus, tra-
branch, / cheloinastoid muscles.

, ,' ! ^Yith branch from third

branch, i . . ,. ,.

(great ' cervical, supplies the

occipital), j skin of the scalP-

f Small occipital,

j Branch to superficial cervical,

I Branch to great auricular,

^ Branch to eommunicans noni.

f External ~] 0 ,

] _ and [Splenius

} internal <

[_ branches,

semispinals,
complexus, trachelomas-

toid muscles.

Branches to form the great auricular,
superficial cervical, and communican-
tes minor.

Internal
branc

11a 1 \ Miisclea of the side of the
'foes, f neck.

sternal ")
'anches, /

External
bm

Skin and larger muscles
of the neck.

[ Branch to phrenic,

Anterior division] Branches to the trapezius, scalenus

j medius, levator anguli scapulae mus-

I cles.

of fourth,

Anterior

divisions,

fifth to eighth,

, , , ( Superficial

Cervical plexus, 1 J.

branches,

Unite with the first dorsal nerve to form
the brachial plexus.

( Superficialis colli,

Ascending. - Auricularis magnus,
( < Occipitalis minor.

Descending. Supraclavicular.

1 Permed by the anterior divisions of the first to the fourth cer-
vical nerves,

344

HUMAN ANATOMY.

Table of the Spinal Nerves.— (Continued.)

Cervical plexus f
( continued ) , \

Deep
branches, \

f Internal set,
I

Brachial plexus,1 <

Above

the
clavicle,

Below

the
clavicle,

Three sub-
scapular,

Circum-
flex,

Musculo-
cutaneous,

External set,

Communi-
cating,

Muscular,

Posterior
thoracic,

Supra-
scapular,

Anterior
thoracic,

Communicating,

Muscular, < ,

t muscles.

Phrenic,

Communicans noni.

Muscular,
Communicating.

To phrenic.

Scaleni, rhomboidei, lon-
gus colli, subclavius.

Serratus magnus.
( External respiratory
nerve of Bell.)

Shoulder joint and supra-
spinatus muscle.

External
branch,

Internal
branch,

Upper,
Lower,
Middle,

Upper,
Lower,

Anterior
branch,

f Pectoralis
\ major.

f Pectoralis
J minor,

i, Pectoralis

( major.

[ Subscapular
\ muscle.

Teres major.

f Latissimus
1 dorsi.

f Shoulder
j joint, and
\ muscles and
[ skin about it.

f Integument
j of palmar sur-
i, face of the
j wrist.

f Integument
Posterior j of dorsal sur-
branch, \ face of the
| wrist.

i Formed by the anterior branches of four lower cervical and first
dorsal nerves.

THE NERVOUS SYSTEM.

345

Table of the Spinal Nkkvks.— (Continued.)

Brachial

plexus,

below the

clavicle
contirid,

Internal

f Anterior ] Integument of
a nd

internal j auu. inner side of

cutaneous, 1 posterior f the arm.
branches, J

Lesser internal [integument of the inner
cutaneous < sjcje 0f h,a arrrL
(Wrisberg's), [

Median, -

f Muscular,

Anterior

interosseous,

Palmar

cutaneous,

Branch to

the musclesi of

the thumb,

Digital

branches,

1

( Superficial anterior mus-
J cles, except flexor carpi
( ulnaris.

fDeep anterior muscles, ex-
cept the inner half of
flexor profundus digi-
torum.

J Ball of thumb and palmar
\ surface of the hand.

Opponens, outer head of
small flexor and ab-
ductor.

fBoth sides of thumb, in-
: dex and middle fingers
i and radial side of ring
[ finger.

Articular, j (Elbow)

Ulnar,
in forearm,'

f Inner half of deep flexors
Muscular, j and flexor carpi ulnaris.

Cutaneous, { Skin of the palm.

(Both sides of little finger
| and ulnar side of ring
[ finger.

Dorsal

cutaneous,

Articular, { (Wrist).

I In. ir,
in hand,

Superficial

palmar,

Deep
palmar,

f Skin of both sides of little
j linger, ulnar side of ring
\ finger and palmaria
brevia muscle.

f luicrossei lumbricales, ad
: ductor pollicis, inner

\ head of flexor brevis
pollicis.

34G

HUMAN ANATOMY.

Table of the Spinal Nerves. — (Continued.)

Brachial

plexus,

below the

clavicle,

cont'd,

Musculo-
spiral,

Dorsal

nerves,

Posterior
divisions,

Anterior
divisons,i

Lumbar
nerves,

Posterior
divisions,

Anterior
_ divisions, \

f Supinator longus, extensor
Muscular j carpi radialis longior, tri-
branches, i ceps, anconeus, brachialis

[ anticus.

f Supplies adjoining sides of
_ ,. , j thumb and index finger,

Kadial, -j index and middlej middla

[ and ring fingers.

(Inner side of arm, elbow,
radial side of forearm and
wrist.

f Posterior brachial and radial
Posterior j muscles, except those sup-
interosseous, i plied by ulnar (muscular
[ branches ) .

External
branches,

Internal
branches,

Upper six

( thoracic

intercostals ) ,

^Muscles and skin of the back.

First intercostal crosses the
axilla to join the lesser in-
ternal cutaneous ( Wris-
berg's ) .

Lateral
cutane- ■<
ous,

Ante-
rior,

Poste-
rior,

f Skin of
■j chest and
(. mamma?.

Skin over
scapula

and lower
dorsal
region.

r.

Lower six i The ]agt dorgal gWes off the

(thoracico- ^ dorsilumbar to the quad-

abdominal , ratus lumborum muscle,

intercostals ) , [_

External
branches,

Internal
branches,

I Muscles of
back.

the skin of the

f The four upper unite to form the lumbar
plexus. The fifth, with a branch from the
fourth, joins the sacral nerves to form the
lumbosacral cord.

I

l To the walls of chest and abdomen.

THE NERVOUS SYSTEM.

347

Table of the Spinal Nerves. — (Continued.)

Ilio-
hypogastric,

Lumbar
plexus.

f Skin of gluteal region, ob-
lliac, I lique muscles of abdomen.

Hypo- I Skin of hypogastric region
gastric, I

and oblique muscles.

Ilio-
inguinal,

Genito-
crural,

External
cutaneous,

( Skin of inner and upper part of thigh, scro-
ll turn, labium (in female).

f Cremaster muscle, round liga-
Genital, | ment (in femaie).

Posterior,

Anterior,

Obturator, \ Posterior,

Articular,

Crural, { Skin of front of thigh.

( Skin of outer front aspect of
Anterior, | thigh

Skin of outer back aspect of

/ Skin of

\ thigh.

I Femoral artery.
< Adductor muscles.

Is"

Synovial membrane of knee-
joint.

Accessory f Branch to hip- joint, branch to anterior
obturator, \ branch of obturator nerve.

f Sartorius
Middle j muscle,
cutaneous, \ skin of

[_ thigh (ant,).

f Skin of
Internal j inner

cutaneous, 1 aspect of
leg.

Anterior,
division,

Anterior

crural,

Skin of

-, inner side of
saphenous, j foot>

Lone

Posterior,
division]

f Muscles

j of the an-

_ _, . terior and

f Muscular. J ];it|,n||

aspect of

J [ thigh.

[_ Articular, j Knee joint.

348

HUMAN ANATOMY.

Table of the Spinal Nerves— (Continued. )_

Sacral
nerves,

! Posterior
I divisions,

External

and internal

branches,

Muscles and skin of the
back.

| Anterior f The four upper joining with the lumbosacral
[ divisions, \ cord form the sacral plexus.

Sacral
plexus,

Obturators, gemelli, quadratus femoris and
Muscular, | piriformis.

Superior j Qiu^ei muscles and tensor vaginae femoris.

Inferior f gkin of ^ anug

rhoidal, (

rineal structures.

hemor
Pudic, ■{ Perineal, < Peri

< Skin of the penis.

To hip joint.

i Gluteus maximus.

Dorsal nerve of
the penis,

Articular

{

Small
sciatic,

Inferior
gluteal,

Great
sciatic.

Internal
cutaneous,

Ascending
cutaneous,

Articular,
Muscular,

f Branch to skin of inner and
upper part of thigh.

H

Inferior pudendal, skin of

scrotum, labium in fe-
^ male.

I Skin over gluteus maximus.

-J Hip joint.

/ Muscles of inner and pos-
\ terior part of thigh.

Bifurcation, { ^Sal,' } PoPliteaL

Internal
popliteal,

Articular
branches,

To knee joint.

Muscular "1 To muscles of the posterior aspect of

branches, J the leg.

THE NERVOUS SYSTEM.

349

Table of the Spinal Nerves. — (Continued.)

Conmmnicans \ skin of outer side of the foot
poplitei, j

Internal

popliteal

[continued)

Posterior tibial
(continuation),

, ( Deep muscles of the

Muscular, j c.{,f

Plantai

cutaneou

Skin of inner side of
sole and heel.

:, {

Articular, j To ankle joint.

j Internal plantar,

Bifurca-
tion, 1 External plantar.

Internal

f Cutaneous,
Muscular,

plantar, \ Articular,

'[_ Four digital.

External
plantar,

Supplies the outer
side of the fourth
and both sides of
the fifth toes. Mus-
cular branch.

External

|H)pliteal *
( peroneal),

Articular, j To knee joint.

Two

cutaneous,

Anterior

tibial,

M usculo-
cutaneous,

Communieans peronei.

External
or tarsal
branch, J

Internal
branch.

Internal
branches,

External
branch,

1 Tarsal and metatar-
sal joints.

f Inner and dorsal, ad-
j joining sides of
\ great and second

I toes.

< To skin of inner side

\ of foot and ankle.

f To dorsum of adja-

J cent sides of third,

fourth

toes.

and fifth

350 HUMAN ANATOMY.

THE SYMPATHETIC NERVOUS SYSTEM.

The sympathetic system (sympatheticus) , like the cerebro-
spinal axis, is double, consisting of a gangliated cord {truncus
sympatheticus) on each side, extending the entire length of the
vertebral column, and numerous nerve fibers, both communicat-
ing, by which it anastomoses with the cerebrospinal axis, and
distributory, by which the blood vessels and viscera are supplied.

Branches of the gangliated cords . ascend through the
carotid canal to communicate with the ganglia of the fifth
"cranial nerve, and also with each other through the ganglion of
Ribes, situated upon the anterior communicating artery. They
also communicate below in the ganglion impar (ganglion coccyg-
eum impar), located in front of the coccyx.

The ganglia of each cord correspond very nearly in posi-
tion and number to the vertebra?, except in the cervical region,
where there are but three : cervical three, dorsal twelve, lumbar
four, sacral five.

From the gangliated cords three important plexuses are
given off — the cardiac, solar, and hypogastric — situated in the
thoracic, abdominal and pelvic cavities, respectively.

Cranial Ganglia — Ganglia Connected ivitli the Fifth Cranial
Nerve. — Besides the Gasserian ganglion upon the root there are
four — ophthalmic, sphenopalatine, otic and submaxillary — each
of which has three branches of communication or roots — motor,
sensory and sympathetic — besides several branches of distribu-
tion.

The ophthalmic, or ciliary ganglion (ganglion ciliare), is
' situated in the orbit between the external rectus muscle and
I optic nerve upon the first division of the fifth cranial nerve.

Its sensory root (radix longa ganglii ciliaris) is from the
nasal branch of ophthalmic, motor root (radix brevis ganglii
ciliaris) from the motor oculi or third, and sympathetic from
the cavernous plexus.

Its branches are the short ciliary nerves (vide Eye).

Sphenopalatine, or Meckel's (ganglion sphenopalatinum) ,
the largest, is situated in the sphenomaxillary fossa upon the
superior maxillary, or second division of the fifth.

Its sensory root is derived from the superior maxillary, its
motor root, from the facial, through means of the Vidian, and
its sympathetic from the carotid plexus. Its branches are : —

1. Ascending (rami orbitales) ;

} -Irterv

To*UtJt*\

7c TrTnptiftiehra/H'Ji
■jfolos.

From l**£trrz£aLi \W*-*
fn n

J>t tm 3 ~?i'.r> .-. j/. I 'cm >.

Ophthalmia -rtasit. It
trre

V^jryi Superficial flrf/wKz//rv/*J'asia/A*rrr

i /reuniting fc-r*0m/4r&/

, .tt./ its 6rajt&M .

..!>,.; -

RnmSfJlmtal Xern ^,

Srvmf^Jij'.a/ A'tri't "~~^*J

A^-yi.-reponyir,,! lr,iri,-Acl, .,r'

.iW..*™*,^ ^

.^

»mVtlu,„!,„r.V<r„ —»=

*

•ms*[ma*rjam -^^

A

— — ^A

^>v,

/'"

JW^Kn £^&

From. CoccfgealXerrx

Fig. 124.
The sympathetic system.

THE NERVOUS SYSTEM. 35]

f Anterior, or large palatine (». pilar
Unas and rior 1 .
2. Descending, or pala- ! Middle, or external palatine (». pala-
tine [mi. palatini \ , j /i'hi/s melius),

\ Posterior, or small palatine (». pato-
is tinus posterior) ,

f Pos
{ Na

Posterior superior nasal (rami namks
3. Internal, -{ posteriores superiores),

Fasopalatine (n. nasopaiat&nus) ,

4. Posterior,

Vidian (>i. canalis pterygoidea),
Large superficial petrosal (n. petrosus

supcrficialis major) ,
Deep petrosal (n. petrosus profundus),
Pharyngeal branch.

The Vidian nerve (n. canalis pterygoidea) passes from the
baj?k part of Meckel's ganglion through the foramen laeerum
medium, where it divides into the large superficial and deep
petrosal nerves. Jt gives off the upper posterior nasal branches
to the mucous membrane of septum, orifice of Eustachian tube.
and roof of the nose. Or, more correctly, the Vidian is formed
by the union of the great petrosal (large superficial petrosal)
from the facial and the large deep petrosal from the carotid
sympathetic, runs forward through the Vidian canal, and joins
the sphenopalatine ganglion (Meckel's). In this description,
the nerves given off to the nasal mucous membrane must be
considered branches from the ganglion inclosed in the same
sheath.

The large superficial petrosal branch (n. petrosus super-
firiahs major) enters the cranium through the foramen laeerum
medium, passes beneath the dura mater and Gasserian ganglion,
enters the hiatus Fallopii, receives a branch from the tympanic
branch of the glossopharyngeal (Jacobson's), and through the
aqueductus Fallopii to terminate in the geniculate ganglion of
the facial nerve.

The large deep petrosal branch (n. petrosus profundus)
crosses the foramen Laeerum medium to the carotid canal, where
it joins the carotid plexus of the sympathetic.

The pharyngeal or pterygopalatine nerve descends from the
back part of the ganglion through the pterygopalatine canal, to
supply the upper part of the pharynx.

Besides the Vidian and its branches there are two other

petrosal nerves (vide Facial Sfvw), the small and external

petrosaL

352 HUMAN ANATOMY.

The small petrosal connects the geniculate ganglion of the
facial;, within the aqueductus Fallopii, with the otic ganglion.

The external petrosal connects the geniculate ganglion of
the facial, within the same canal, with the sympathetic plexus
of the middle meningeal plexus.

The otic or Arnold's ganglion (ganglion oticum) is placed
below the foramen ovale upon the inferior maxillary nerve, or
third division of the fifth.

Its sensory root is derived from the auriculotemporal
branch of the inferior maxillary ; the motor root, from the inter-
nal pterygoid branch of the same; the sympathetic root,, from
the plexus on the middle meningeal artery. Branches are dis-
tributed to the tensor palati (n. tensoris veil palatini) and ten-
sor tympani (n. tensoris tympani) muscles.

The submaxillary ganglion (ganglion submaxillare) is
placed above the deep portion of the submaxillary gland.

Its sensory root is derived from lingual branch of inferior
maxillary; its motor root, from the facial nerve through a
branch of the chorda tympani; and its sympathetic, from the
plexus of the facial artery.

Besides these ganglia, situated upon branches of the tri-
facial nerve, the following are found within the cavity of the
cranium : —

Ganglion of Ribes, on the anterior communicating artery;
Ganglion of Bidder, on the middle meningeal artery;
Ganglion of Laumonier, on the internal carotid artery;
Ganglion of Cloquet, on the nasopalatine nerve in the incisor fossa;
Ganglion of Bochdaleck, near the sphenopalatine ganglion.

Cervical Ganglia. — The cervical ganglia consist of three, —
superior, middle, inferior, — of which the superior is the largest
and the middle the smallest. These are connected above with
the cranial ganglia, below with the thoracic ganglia, and com-
municate with each other.

The superior cervical ganglion (n, caroticus internus) lies
opposite the second or third cervical vertebra, behind the inter-
nal carotid artery. It is connected with the middle ganglion,
the upper four cervical, and tenth and twelfth cranial nerves,
distributes branches to the carotid (internal), cavernous (plexus
cavernosus) and pharyngeal plexuses, and gives off the superior
cardiac nerve to the cardiac plexus (plexus caroticus internus).

The middle cervical ganglion (ganglion cervical medium)
lies upon inferior thyroid artery, opposite fifth cervical vertebra.
It is connected with the upper and lower ganglia and spinal

THE NERVOUS SYSTEM. 353

nerves, and gives off the middle cardiac nerve (n. cardiacus
medius) to cardiac plexus.

The inferior cervical ganglion (ganglion cervicale inferius)
lies internal to the superior intercostal artery, below the last
cervical vertebra. It is connected to the middle ganglion, first
thoracic, lower cervical nerves, forms the vertebral plexus, and
gives off the inferior cardiac nerve (n. cardiacus inferior) to
cardiac plexus.

Thoracic ganglia (pars thoracalis) lie upon the heads of
the ribs on each side of the vertebral column. They are con-
nected with the inferior cervical ganglion above, the lumbar
ganglion below, the dorsal spinal nerves behind, and give off
internal branches divided into two sets of six each — -upper and
lower.

internal branches from upper set are distributed to the
pulmonary and aortic plexuses (plexus aorticus thoracalis), and
internal branches from lower set unite to form the three splanch-
nic nerves — great splanchnic (n. splanchnicus major), lesser
Bplanchnic (n. splanchnicus minor), renal splanchnic, — distrib-
uted respectively to the semilunar ganglion, renal and supra-
renal plexuses, and to renal and celiac plexuses.

The lumbar ganglia (pars lumbalis) lie along inner mar-
gin of the psoas muscle. They communicate above and below
with the other ganglia and with the lumbar spinal nerves, and
give off internal branches which form the hypogastric plexus.

The sacral ganglia (pars sacralis) are situated internal to
the anterior sacral foramina. They unite below in front of the
coccyx iti the coccygeal ganglion, or ganglion impar. They
communicate with the sacral nerves, join the pelvic plexus, and
scud branches on the middle sacral artery.

Cardiac Plexus (plexus cardiacus). — The cardiac plexus.
formed from the superior, middle and inferior cardiac nerves
from the cervical ganglia, and the cardiac branches from the
pneumogastric and recurrent laryngeal, consists of two portions
— the superficial and deep.

The superficial cardiac plexus, situated beneath the arch of
the aorta, is formed by the left superior cardiac nerve and the
left inferior cervical cardiac nerve, and contains the cardiac
ganglion of Wrisberg (ganglion cardiacum [Wrisbergi] ) . It
form- part of the anterior coronary plexus, and sends branches
to the left anterior pulmonary plexus.

Tin' deep cardiac plexus lies between the arch of the aorta
and trachea, and receives all the cardie nerves except the two
mentioned above. It forms part of the anterior coronary

23

354 HUMAN ANATOMY.

{plexus coronarius cordis anterior) and posterior coronary
{plexus coronarius cordis posterior) plexuses.

The solar plexus {plexus cceliacum), or "abdominal
brain," consists of ganglia and a network of nerve branches,
formed chiefly from the branches of the two great splanchnic
nerves and branches from the right pneumogastrie. It is sit-
uated between the aorta and the crura of the diaphragm and
the stomach, and surrounds the superior mesenteric artery and
celiac axis.

Its ganglia are two crescentic ganglionic masses — the semi-
lunar ganglia {ganglia coeliaca) — the largest in the body — sit-
uated in front of the crura of the diaphragm. They are com-
posed of small ganglia aggregated together. From the solar
plexus and semilunar ganglion are derived numerous branches
which are distributed as plexuses over all the abdominal arteries,
as follows: —

Cceliac {plexus cceliacus) , Spermatic (plexus spermaticus) ,

Gastric [plexus gastricus supe- Aortic (plexus (tortious abclomi-

rior) , nalis) ,

Hepatic (plexus hepaticus) , Superior mesenteric (plexus mes-

Splenic (plexus lienalis), entericus superior),

Phrenic (plexus phrenicus), Inferior mesenteric (plexus rnes-

Suprarenal (plexus suprarenalis) , entericus inferior),

Renal (plexus renalis) , Ovarian (plexus arterke ovaricce),

The hypogastric plexus {plexus hypogastricum) is sit-
uated below the bifurcation of the aorta, in front of the sacrum,
and is formed by branches from the lumbar ganglia and aortic
plexus. It divides into two parts which, with branches from
the sacral ganglia and nerves, become the pelvic plexuses.

The inferior hypogastric or pelvic plexus on each side
gives off the following branches : —

Vaginal plexus, Inferior hemorrhoidal (plexus

Tuemorrlioidalis inferior) ,

( Small cavernous "|

nerves (n. oavernosus j

Prostatic plexus/ penis minor), \

(plexus prostaticus) ,\ Large cavernous j " '

nerves (n. oavernosus I

(_ major ) , J

Vesical plexus (plexus vesicalis), Uterine plexus.

ORGANS OF SPECIAL SENSE.

T 1 1 E NOSE.

The nose (organon ol) 'actus), the special organ of smell,
consist* of two parts, — the external prominence, or nose proper,
and the internal cavities, or nasal fossae.

fc&-"NASAL

SEPTA
OF S

L branch)

UPERIOR r
ASAL 1

Fig. 125.

The olfactory nerves and nerves of common sensation
to the nose. (Ei-kley.)

The nose proper is made up of a cartilago-osseons frame-
work covered with muscles (vide Muscles) and skin, and lined
with mucous membrane. The osseous portion is formed by the
margins of the anterior meatus (vide Osteology).

The cartilaginous portion consists of an upper (cartilago
nasi lateralis) and lower lateral cartilage (cartilago alaris

major) on either side, and the nasal septum dividing the nasal

cavity into two nasal fossae durum nasi).

Vrtenes are from nasal branch of ophthalmic and infra-
orbital, nasal artery From superior coronary, and branches of
the lateralis nasi.

(355)

356 HUMAN ANATOMY.

Veins empty into the ophthalmic and facial veins.

Nerves from infratrochlear, infraorbital and facial.

The nasal fossae (cavum nasi) are the two bony cavities
already described (vide page 45). They are lined throughout
with mucous membrane (membrana mucosa nasi) called
Sclmeiclerian membrane, which is continuous with the antrum
of Highmore, frontal, ethmoidal and sphenoidal sinuses, with
the conjunctiva through the lachrymonasal duct, with the
pharynx through the posterior nares (choanal), and with cavity
of the tympanum through the Eustachian tube. Its epithelium
is columnar, ciliated in the lower part and in the. sinuses, and is
columnar, but not ciliated, in the membrane to which the olfac-
tory nerve is distributed.

Arteries are anterior and posterior ethmoidal from the
ophthalmic to the roof, frontal and ethmoidal sinuses, spheno-
palatine from the internal maxillary to the mucous membrane
of the spongy bones, septum, and meatuses, and alveolar from
the internal maxillary to the antrum.

Veins empty into facial, ophthalmic, and beginning of
great longitudinal sinus.

Nerves are : —

Olfactory, or first cranial, the special nerve of smell, is dis-
tributed over the upper third of the septum and superior turbi-
nated bones.

Anterior dental branch of superior maxillary to the inferior
turbinated bone and inferior meatus.

Nasal branch of ophthalmic, to the outer walls and septum.
Besides these, the sphenopalatine ganglion, the Vidian, the supe-
rior nasal branch, nasopalatine and anterior palatine also send
branches to the parts.

THE EYE.

The organs of sight comprise the eyeballs (bulbus oculi)
and their appendages and the optic nerves.

The eye is a spherical organ, situated in the anterior part
of the skull, protected in front by several appendages, acted
upon by muscles, and supplied by blood vessels and nerves.

Within the orbit it rests upon a bed of fat, from which it
is separated by a membranous sac — the capsule of Tenon (fascia
bulbi [Tenoni]).

It presents the following : —

Diameters. — Anteroposterior, in the adult, .950 inch;
transverse, .925; vertical, .915; oblique, .9-13.

ORGANS OF SPECIAL SENSE.

357

Fig. 126.

Nasal meatuses and accessory cavities. 1, right termination of the
left frontal sinus; 2, right frontal sinus; 3, probe extending from the
right frontal sinus through the infundibulum into the right nasal
fossa; 4, ethmoid cells; 5, large opening into the maxillary sinus; 6,
anterior antrum of the sphenoid bone; 7, posterior sphenoid antrum;
v. middle nasal meatus; 9, Inferior meatus; i<», Inferior turbinated
bone; 11, probe extending through the nasal dint. (Bishop.)

558

HUMAN ANATOMY.

Anterior and posterior poles are the geometric centers of
the cornea and fundus respectively.

Optic axis (axis optica) is a straight line passing through
the cornea and posterior pole of the eye.

Line of vision, or visual axis (linea visus) , is an imaginary
line which connects the point of fixation with the fovea cen-

81du8 front,
yifttnltia papyr. oss. ethmoid.

Foramina ethmoid,
?roc. orbit, oss. palat.
Corpus oss. sphenoid.

For. optic
ffosura orbit, eup.
Sella turcica \

Spina trochlear. j

Bars orbit, oss. front. !

Fossa sacci lacrim.

Oa nasale

'acies orbit. maxQl.
Froo. uncin. oss.
ethmoid.
Froo. ethmoid, concha*

nasal, inf.

Proo. max ill. conchae

nasal, inf.

canal, palat.

Sinus maxiliarial
PaTs perpondic. oss. palat.

Fig. 127.
Inner wall of orbit and adjacent parts. (His.) (Ball.)

tralis, through the nodal point, usually to the outer side of the
center of the pupil. It forms with, the optic axis as it cuts the
cornea, the visual angle — an angle of from 3° to 7°.

Nodal point is an imaginary point — the center of curvature
of the refracting media — where all the luminous rays pass with-
out deviation.

Equatorial plane, an imaginary plane passing through the
center of the eyeball at right angles to the optic axis, dividing
the globe into two hemispheres — the anterior and posterior.

ORGANS OF SPECIAL SENSE.

359

Equator is the line upon the surface of the glohe where the
equatorial plane cuts it.

Meridional planes are imaginary anteroposterior planes co-
inciding with the axis.

Meridians are the lines upon the surface where these merid-
ional planes cut it.

The capsule of Tenon, tunica vaginalis oculi (fascia
oculi [Tenoni]), is a fascia between the eyeball and the walls
of the orbit, isolating the eyeball and allowing free movement.

Fig. 128.

Horizontal section of right orbit. 1, Horner's muscle; 2, septum or-
bitale; '.',, fibers of the orbicularis palpebrarum muscle; 4, tarsal plate;
5, conjunctival sac; 6, outer palpebral ligament; 7, temporal muscle;
S, wall of the orbit; 9, external rectus muscle; 10, orbital fat; 11, optic
nerve; 12, internal rectus muscle; 13, inner check ligament; 14, inner
wall of the orbit; 15, attachment of the capsule of Tenon (1G) to the
conjunctiva; 17, Tenon's space; 18, outer check ligament; 19, lachrymal
gland; 20, ciliary process; 21, iris. (Ball after Gerlach.)

It i- continuous in front with the subconjunctival connective

tiss iw. and behind with the dura mater, through the sphenoidal

fissure and optic foramen, and consists of two layers — a visceral

investing the posterior portion of the eyeball, and a parietal

lining the cushion of fat on which the eye rests.

The inner aspect is lined with flattened endothelial cells,

and incloses a lymph Bpace communicating with subdural and

subarachnoidean lymph spaces of the optic nerve sheath. It sup-

360

HUMAN ANATOMY.

ports the lachrymal gland, is strengthened by numerous fibrous
bands, and is pierced by the ocular muscles, inclosing them in
imperfect sheaths.

The capsule of Bonnet is the name given to the portion
posterior to the passage of the tendons, and

The capsule of Tenon is then applied to the anterior socket-
like half.

The eyeball (biilbus oculi) is composed of a large, opaque
segment of a sphere, forming about five-sixths of the globe, for-
the protection of its contents, and a smaller transparent seg-
ment of a sphere, implanted upon and continuous with it in

Canal of Schlemm.

8S~^*^^Canal of
«s» Petit.

SlIM'A INTERNAL
' RECTUS

MUSCLE.

Canal for
central artery.

Optic nerve.

front. The optic nerves enter the eyeballs to their nasal side,
in the direction of the axes of the orbit.

It is composed of three tunics or coats : —

1. Sclerotic and cornea,

2. Choroid, iris and ciliary processes,

3. Retina;

And three humors, -or refracting media : —

1. Aqueous humor,

2. Crystalline lens (and capsule),

3. Vitreous humor, or body.

ORGANS OF SPECIAL SENSE. 331

The sclerotic coat, so called from its extreme hardness,
is thicker behind (one twenty-tilth of an inch) than in front
(one-sixtieth of an inch), and presents two surfaces for study —
the external and internal.

The external swrface is smooth and white, and has attached
to it the various muscles of the eye.

The internal surface is grooved for the passage of the
ciliary nerves, and connected to the choroid by a fine areolar
layer — the lamina fusca (laminae fascice sclerce).

Behind, and a little to the nasal side, where the optic nerve
enters, it presents a perforated appearance — the lamina cribrosa
—the larger opening of which — the poms opticus — transmits
the arteria centralis retinae; the others transmit the ciliary ves-
sels and nerves. It is continuous in front with the cornea, over-
lapping it a little on its outer margin.

In structure it is made up of white, fibrous tissue, with a
small quantity of elastic fibers and connective-tissue corpuscles.

The arteries are from the anterior and short posterior
ciliary.

The veins — venous blood removed by venas vorticosse and
the anterior ciliary.

The nerves are from the ciliary.

The cornea is the convex, transparent, nearly circular
tissue forming the anterior one-sixth of the globe. It is from
niie twenty-second to one thirty-second of an inch in thickness.
Its thickness at the periphery is 1.12 millimeters, hence its pos-
terior surface is more curved than the anterior. Its transverse
diameter is a. little greater than the vertical, owing to the over-
lapping of the sclerotic above and below. It is composed of
four layers : —

1. Conjunctival epithelium, or anterior layer {epithelium cornea;),

2. Cornea proper, or sub- f Anterior elastic lamina (lamina

stantaa propria, \ elastica anterior),

3. Posterior elastic lamina "|

I lamina elastica paste- j

' ""' 1 1 ! Cornea proper;

4. Endothelial lining (endo- (Membrane of Deseemet.

thelium camercB ante- |
i ioris) ,

The conjunctival epithelium consists of several layers of
cells (columnar, polyhedral and squamous) covering the ante-
rior surface of the cornea, continuous wiih the conjunctiva.

The anterior clastic lamina is the name given to the outer
epithelial layer of the cornea proper.

362 HUMAN ANATOMY.

The cornea proper is made up of a transparent fibrous
structure, identical with the sclerotic, and consisting of about
sixty layers or lamina, connected by a cement substance inclos-
ing corneal spaces, each of which contains a corneal corpuscle.

The posterior elastic lamina consists of an elastic homo-
geneous membrane, internal to the proper structure of the
cornea, and constituting, with the epithelial lining, the mem-
brane of Descemet, or Demours.

The structure of the cornea is non-vascular, being nour-
ished by channels representing lymphatic vessels, and continu-
ous with the corneal spaces. The nerves derived from the
ciliary nerves are numerous, and form between the outer surface
of the cornea proper and the epithelial covering the subepithelial
plexus, from which is given off* the intraepithelial plexus.

The second tunic consists of the choroid, lining the sclerotic
coat throughout; the iris, the circular curtain suspended in the
aqueous humor and perforated by the pupil; and the ciliary
ligament and muscle at the junction of the two.

The choroid (choroidea) is a dark, reddish-brown, highly
vascular membrane, lining the sclerotic coat from the optic
nerve to the ciliary ligament, where it projects backward in a
number of processes, the ciliary processes. It is in contact
externally with the sclerotic, to which it is attached by the
membrana fusca, and internally with the retina.

The structure consists chiefly of a dense capillary network.

The choroid proper consists of an external and an internal
layer, and is separated from the sclerotic by the lamina supra-
choroidea, continuous with the lamina fusca of the sclerotic, .
and from the pigmentary layer of the retina by the lamina
vitrea.

The external layer or the lamina vasculosa consists of a
capillary network, derived from the larger branches of the short
ciliary arteries, inclosing between the meshes large, star-shaped
pigment cells, which are connected together by a delicate stroma.
They, terminate in the venw vorticosce, which emerge through
the sclerotic midway between the optic nerve and the margin of
the cornea.

The internal layer is also composed of a fine capillary net-
work, derived from the short ciliary arteries> and continuous in
front with the vessels of the ciliary processes. It is called the
tunica Ruyschiana (lamina choriocapillaris) .

The lamina basalis, or membrane of Bruch, is a thin, struc-
tureless layer, separating the pigmentary layer of the retina
from the stroma of the choroid.

ORGANS OF SPECIAL SENSE.

363

The arteries are from posterior ciliary, short ciliary (prin-
cipally in the external layer), and recurrent branches of long
and anterior ciliary.

The veins converge from the vena? vorticosae to form four
or five trunks, which pierce the sclerotic midway between the
optic nerve and corneal margin to join the cavernous sinus.

The nerves are the long and short ciliary.

Fig. ISO.

Vessels of the eye. A, conjunctival vessels; B, anterior ciliary
vessels; 0, vena vorticosa; D, posterior ciliary arteries; E, central
retinal vessels. (Hall.)

The ciliary processes (processus ciliares) are a series of
sixty to eighty pigmented vascular processes arranged circularly
around the lens behind the iris, and composed of the two inter-
nal layers of the choroid folded inward. They are continuous
in front with the ins, and are connected behind with the sus-
pensory ligament of the lens.

The structure is similar to that of the choroid.

Tin: [BIS is a thin, circular curtain, suspended in the
aqueous humor, between the lens and cornea, and perforated by
a circular aperture — the pupil (pupUla).

364 HUMAN ANATOMY.

Its circumference is connected with the choroid, and also
by means of the ciliary ligament with the sclerotic and cornea.
The sclerotic contains in this position, near its junction with
the cornea, a circular canal (lymph canal, or venous sinus), the
sinus circularis iridis, or canal of Schlemm (sinus venosus
sclera?) .

The circumference of the iris is also connected in front
with the cornea by pectinate ligament (ligamentum pectinatum
iridis), derived from the membrane of Descent et.

The structure is composed of four elements : —

. 1. A basement membrane and polyhedral cells, continuous with the
membrane of Descemet;

2. Stroma (stroma iridis) consisting of bundles of fibrous tissue
and cells;

f Circular fibers (m. sphincter pupilkc) ,
,r , „, ; forming the sphincter of the pupil;

6. Muscular fibers, ^ Radiating fibers (m. dilator pupillw) ,
[ forming the dilator of the pupil;

4. Pigment, consisting of polyhedral or round pigment cells, dis-
tributed for the most part to the posterior surface, which, from its
deep-purple tint, has been called the uvea.

The arteries are from the long and anterior ciliary and
from the ciliary processes (from the short ciliary).

The veins join those of the ciliary processes and anterior
ciliary veins.

The nerves are the long ciliary from the nasal branch of
the ophthalmic (first division of fifth), and ciliary branches
from the lenticular or ophthalmic ganglion.

The circular fibers are supplied by the fibers from the
third or motor oculi, the radiating fibers are supplied by the
sympathetic.

The membrana pupiUaris is a delicate, vascular membrane,
closing the pupil in the fetus, continuous at its margin with
the iris. It usually disappears about the eighth month, but
occasionally persists.

The ciliary muscle (m. ciliaris) is a grayish, circular band
of unstriated fibers, attached to the fore part of the choroid.
It consists of two sets of fibers — the external radiating fibers
(fibrce meridianales [Bruckei]), dilator pupillce — arising from
the junction of the sclerotica and cornea, and is inserted into
the choroid opposite the ciliary processes; the internal circular

ORGANS OF SPECIAL SENSE.

365

Fig. 131.

The structure of the human retina. I, pigment epithelium layer;
II, rods and cones; III, granules of the visual cells; IV, outer plexi-
form layer; V, layer of horizontal cells; VI, layer of bipolar cells;
vil, layer of amacrine cells; VIII, inner plexiform layer; IX, gan-
glion cell layer; X, lay«r ol' nerve fibers; 1, diffuse amncrin.' cell;
2, diffuse ganglion cell; 3, centrifugal nerve fiber; l, amacrine asso-
<i;ihon fibers; .J, neuroglia cells; 6, Mullcr's radial fibers. (Ball after

Cfreeff.)

366

HUMAN ANATOMY.

fibers {fibrm circular -es [Mulleri]), sphincter pupillce, pursue a
circular course around the insertion of the iris.1

It is the muscle of accommodation, its contraction draw-
ing on the ciliar}? processes, relaxing the circular fibers described
as the ligament of the lens, and allowing the anterior surface
of the lens to become more convex by its inherent elasticity.

The retina is a delicate, white, nervous membrane, the

Fig. 132.

Diagram of the retinal vessels. 1, superior temporal artery; 2,
superior temporal vein ; 3, superior nasal vein ; 4, superior nasal ar-
tery; 5, inferior nasal vein; 6, inferior nasal artery; 7, inferior tem-
poral vein; 8, inferior temporal artery; 9, macula lutea; 10, macular
veins. (Ball.)

expansion of the optic nerve. It lines the eyeball, being in
contact externally with the choroid and internally with the
vitreous body. It terminates in front near the ciliary body in

l Quite recently it has been the consensus of opinion among
anatomists that the circular fibers are but partially attached to the
radiating fibers, pursuing a circular course around the attachment of
the iris. These circular fibers are sometimes designated the "ring
muscle" of Miiller, and were formerly described and regarded as the
"ciliary ligament."

ORGANS OF SPECIAL SENSE. ;;<;,

an irregular margin, the ova serrata, but is prolonged forward
as the pars ciliaris to the iris. Its internal posterior surface
presents at a point corresponding to the axis of the eyeball a
small, round, elevated spot of yellowish color {macula lutea),
or yellow spot of Summering, in the center of which is the
fovea centralis, a central depression, the region of most acute
vision, and about one-tenth of an inch to its nasal side, at a
point corresponding to the axis of the orbit, the entrance of
the optic nerve, an oval, bluish-white depression, with distinct,
often pigmented margins, a region destitute of vision and called
the optic disk (porus opticus). Its center presents the arteria
centralis retina1, giving branches to the upper and lower nasal
side of the macular region;

The structure of the retina is exceedingly complex, con-
sisting microscopically of ten distinct layers from within out-
ward, as follows: —

1. Membrana Urmtans interna, the most internal layer of the
retina, forms tin- base of the connective-tissue framework' of the retina,
from which it is derived.

2. Tlie fibrous layer consists'of nerve fihers, the termination of the
optic nerve liber-.

3. The vesicular layer, composed of a layer of large, flask-shaped
ganglionic cells. It is wanting in the macular region.

4. Tin- iiim >• molecular lay< r i- composed of a- layer of glandular-
like structure, forming a reticulum inclosing minute granules.

5. The vn/ner nuclear layer is composed of three sets of nuclear
bodies, the first resembling bipolar nerve cells, the second without
branches, and third continuous with the radiating fibers, or fibers of
VI filler.

G. The ouicr molecular layer resembles closely the inner molecular
layer, from which it differs only by containing branched stellate cells.

7. The outer nuclear Un/er is composed of several layers of nuclear
cells, separable into two kinds, the rod granules and cone granules, both
continuous with the rods and cones of Jacob's membrane.

s. The membrana Umitans externa is, like the internal limiting
membrane, derived from the radiating fibers, or fibers of Mailer.

'.i. Jacob's membrane, or the layer of rods and cones, consists of
two distinct kinds of cells — the rods and cones, distributed alternately
throughout this layer, the rods being much more numerous.

the rod- are solid, stand perpendicularly to the surface, and con-
-i-t of two portions — an outer striated and an inner granular.

The cone- are flask-shaped, with their pointed extremities toward
the choroid. Thej a No consist of two portion- — an outer striated and
an inner granular.

ID. The pigmentary layer was formerly described as a layer of the
choroid. It has received the name of tapetum nigrum, ('insisting of a
layer of pigmented hexagonal epithelial cells.

In main of tin' lower animal-, this layer on the posterior surface
i- destitute <<i pigment* and is called from its iridescent lustre the

!<![,</ Km hitidjnii.

368 HUMAN ANATOMY.

The radiating fibers, or fibers of Midler, consist of connective-
tissue fibers, connecting all the layers together, and forming the mem-
brana li mi tans interna and the membrana limitans externa.

The structure of the retina at the macula lutea differs in
the following manner : the cones only, of Jacob's membrane are
present; the Tesicnlar layer consists of several strata, and in
the outer nuclear layer only the cone fibers are present.

At the fovea centralis only the cones of Jacob's membrane,
the outer nuclear layer, and the internal granular layer are
present.

The arteria centralis retina? supplies only as far as the
inner nuclear layer.

THE HUMORS OF THE EYE.

The aqueous humor {humor aqueus) is a transparent,
alkaline, serous fluid, small in quantity, weighing four to five
grains, and filling the anterior and posterior chambers of the
eye. It is composed of water, 96.7; extractive matters, prin-
cipally chloride of sodium and albumin, 0.1.

The anterior chamber (camera oculi anterior) is the space
(about 2.7 millimeters in depth) between the iris and the
cornea.

The posterior chamber (camera oculi posterior) is the
space between the anterior surface of the lens and the iris. It
amounts to a space only at the circumference, the two being in
contact at the posterior surface.

The crystalline lens (lens crystallina) is a biconvex,
transparent, elastic body, suspended with its capsule (capsula
lentis), surrounded by the ciliary processes. It is more convex
on its posterior surface (anterior surface has an average radius
of 10 millimeters, the posterior 6 millimeters), and is received
into a hollow depression in the hyaloid membrane.

It measures about one-third inch in diameter, one-fourth
inch in axis, and weighs from four to four and one-half grains.

Its index of refraction increases from the periphery to the
center, with an average of 1.4371.

Its composition consists of about 60 per cent, water; solu-
ble albuminous matter, 35 per cent.; insoluble albuminous mat-
ter, 2.5 per cent. ; cholesterin and fat, 2 per cent.

The structure of the lens consists of concentric laminge,
made up of hexagonal prisms, about one-'five-thousandth inch
in breadth, united laterally by dentated margins, and curving

ORGANS OF SPECIAL SENSE. .;,;;,

round the borders of the lens. The lamina' are arranged into
three triangular segments.

The centra] portion, or nucleus, is unstratified, while the
miter layers, or cortex, each contain a nucleus, forming a
nuclear layer.

The capsule of the lens (capsula lentis) is a clear, elastic,
brittle memhrane, inclosing the lens, and held in position hv
the suspensory ligament. Its anterior layer is thicker, and is
attached to the lens by a layer of polygonal nucleated cells,
which break down post-mortem to form the liquor Morgagni.

The canal of Petit (spatia zonularia) is ahout one-tenth
inch in diameter, encircling the capsule of lens. Its hase is
formed by the capsule, and it is hounded in front by suspensory
ligament, behind by the hyaloid membrane of the vitreous
humor.

The suspensory ligament, or zonula of Zinn (zonula cili-
aris), is a thin, transparent structure, extending from the mar-
gins of the hyaloid fossa, where it is continuous with hyaloid
membrane, to the anterior margin of the lens.

Tin: vitreous humor, or body (cor/nis vitreum), is a
clear, albuminous fluid, filling the cavity of the retina, hollowed
out in front — hyaloid fossa (fossa hyaloidea) — for the lens,
and inclosed in the hyaloid membrane (membrana hyaloidea).
It is composed! of water, with a few salts and a little albumin.

Its structure is finely reticular, particularly in the fetus.

Thi' canal of Stilling, canal of Cloquet, or hyaloid canal
(canalis hyaloideus) , is a canal extending in the fetus from the
entrance of the optic nerve to the lens, containing fluid, and
lined by a fold of hyaloid membrane.

In the Ictus a canal extends parallel hut independent of
tlii-- and transmits a minute artery to the capsule of the lens.

The hyaloid membrane (membrana hyaloidea) is a delicate
capsular memhrane, investing the vitreous body, excepting its
anterior surface, sends fibrous septa into the structure of the
Vitreous, and IS continuous in front with the posterior capsule,
and with the anterior capsule through the suspensory ligament.

\l I 8< l.i:s OF Till': EYEBALL.

Recti - Si periob (m. rectus superior) .— Origin, sheath, of

the optic nerve and upper margin of optic foramen; insertion,
into upper surface of sclerotic coat, three or four lines from

corneal margin; action, rotates the eyeball upward: nerve], third

cranial.

24

370

HUMAN ANATOMY.

Eectus Inferior (m. rectus inferior). — Origin, from
lower and inferior part of optic foramen (ligament of Zinn —
annulus tendineus communis) ; insertion, into lower surface of
sclerotic; action, rotates the eyeball downward; nerve, third
cranial.

Rectus Interntjs (m. rectus internus). — Origin, same as

£?

Rl-

The orbital muscles. Lp, levator palpebrse superioris; Os, supe-
rior oblique; lis, superior rectus; Rl, external rectus; Oi, inferior
oblique; Ri, inferior rectus; Rm, internal rectus; Tr, trochlea. (Ball.)

inferior rectus; insertion, -into inner surface of sclerotic; action,
rotates the eyeball inward ; nerve, third cranial.

Eectus Exteenus (m.- rectus lateralis). — Origin, by two
heads* — lower, from ligament of Zinn and lower margin of
sphenoidal fissure ; upper, from outer margin of optic foramen ;
insertion, into outer surface of sclerotic; nerve, abducens, or
sixth cranial. Passing between the two heads are the ophthal-
mic vein, the third, nasal branch of fifth and sixth nerves.

ORCAXS OF SPECIAL SENSE.

371

Superior Oblique (m. obliqims superior). — Origin, from
iuuer margin of optic foramen. Its tendon passes through a
pulley {trochlea in. obliqm superior) near the internal angular
process of the frontal bone; insertion, into sclerotic between
external and superior recti, midway between entrance of optic
nerve and the cornea; action, rotates the eyeball on its axis;
nerve, fourth, or patheticus.

Inferior Oblique (in. obliquus inferior). — Origin, orbital
plate of superior maxilla; insertion, near that of superior

Supra-orbital

Lacrimal

Muscular and ciliary

Anterior meningeal
Ophthalmic

Superior rectus
Levator palpebral saperioris

Anterior ethmoidal
Muscular trunk

Ciliary

Arteri:\ centralis
Posterior ethmoidal

Optio nerve
Internal carotid

Fig. 134.
Ophthalmic artery and branches. (Hall, after Merkel and Kallius.)

oblique, between external and superior recti; action, rotates the
eyeball on its axis; nerve, third cranial.

The arteries oi the globe of the eye are: —

1. The short ciliary, enter through the sclerotic around the
optic nerve, to supply the choroid and ciliary processes.

2. The long ciliary arteries, two in number, pierce the
Bclerotie, ran forward between the choroid and sclerotic to the
ciliary muscle, which they Supply, and where they form an

anastomotic circle about the iris.

:;. The anterior ciliary art cries, five or six in number, enter
the sclerotic in front, supply the ciliary process, and anastomose
about the irb.

372 HUMAN ANATOMY.

4. The arteria centralis retina' supplies the retina, dividing
into four or five branches, which enter as deeply as the inner
nuclear layer.

The other arteries supplying the eye and its appendages
are derived from the ophthalmic branch of the internal carotid
(the same source as the ciliary arteries), the anterior cerebral
branch of the internal carotid, and the infraorbital branch of
the internal maxillary.

The branches of the ophthalmic are : —

Lachrymal ;

Supraorbital;

Anterior and posterior ethmoidal;

Palpebral;

Frontal ;

Nasal. (For description see Arterial System.)

The veins of the eyeball emerge as the vence vorticosce, unite
with the other veins to form two main trunks — the ophthalmic
and inferior ophthalmic veins — to terminate in the cavernous
sinus. The ophthalmic vein anastomoses freely with the angu-
lar vein, the commencement of the facial at the inner angle of
the orbit.

The nerve of special sense, the optic or second cranial, sup-
plies the eye and its appendages; motor nerves, the third and
fourth ; branches of the fifth and sixth, and filaments from the
sympathetic.

Sensory nerve, ophthalmic division. of the trifacial, or fifth
cranial {vide Cranial Nerves).

Sympathetic branches, derived chiefly from the ciliary gan-
glion, Meckel's ganglion, and the cavernous and carotid plexuses
(vide Cranial Sympathetic Ganglion).

APPENDAGES OP THE EYE.

The appendages of the eye (tutamina oculi) include: The
eyebrows (supercilia) , the eyelids (palpebrce), conjunctiva, and
the lachrymal apparatus (apparatus lacrimalis) ; lachrymal
gland, lachrymal sac, nasal duct.

The eyebrows (supercilia) are the elevated arches of skin
surmounting the upper margins of the orbits, covered with
short, thick hairs.

The eyelids (palpebrce) are two movable folds, covering
and protecting the front of the eye. The upper lid (palpebra
superior) is larger, longer; and more movable, being supplied
with a special muscle — the levator palpebra? superioris.

ORGANS OF SPECIAL SENSE. 373

The lids are separated by an elliptical fissure — the fisswra
palpebrarum — and connected at their angles of junction by the
outer (angulus oculi lateralis) and inner (angulus oculi me-
dialis) canthi.

On the nasal side the lids are separated by a triangular
space — the lacas lacrvmalis — at the outer angles of which are
the lachrymal papilla', surmounted by the panel am lacrimale,
the commencements of the lachrymal canal. The lacas lacri-
malis is filled by the caruncula lacrimdlis, a mass of follicles
resembling the "Meibomian glands, and covered by the con-
junctiva.

The structure of the eyelids, from without inward, is as
follows: —

Skin, subcutaneous areolar tissue, fibers of the orbicularis muscle,
tarsal cartilage, fibrous membrane, Meibomian glands, vessels and
nerves ;

The skin is thin, and attached by a very loose areolar tissue to the
muscle beneath;

The fibers of the orbicularis are pale, thin, and act involuntarily;

The tarsal cartilages are two plates of firm connective tissue; the
superior (tarsus superior), the larger, is semilunar in shape, the in-
ferior (tarsus inferior) is elliptical. The inner margins are fixed to the
orbit by tendo oculi;

The fibrous membrane of the litis, or tarsal Uga/ment, passes over
the anterior surface of the tarsal cartilage, being attached to its free
margin below and to the margin of the orbit externally:

The Meibomian glands (glandules tarsales [Meibomi] ), about thirty
in number in the upper, a U>\v less in the lower lid. are arranged ver-
tically on the inner surface of the cartilages; they are straight, seba-
ceous follicles, into which open a number of secondary follicles, termi-
nating above in a blunt extremity, and opening below on the free margin
of the lids by small foramina, corresponding to the number of tubules;

The eyelashes (cilia), are arranged on the free border of the lids
ill two or three rows.

The CONJUNCTIVA is the mucous lining membrane of the
front of the eye. It consists of two portions — the bulbar.
reflected over the sclerotic and cornea, and the palpebral por-
tion; lining the internal surface of the lids.

The bulbar portion {tunica conjunctiva bulbi) is loosely
connected with the sclerotic, hut over the cornea if becomes
very thin, consisting only of the epithelial layer.

The palpebral portion (I unit a conjunctiva palpebrarum) is
thick, highly vascular, and contains many papilla'. At the
inner angle of the eye it forme a semilunar fold, the plica semi-
lnnari- [plica semilunaris conjunctiva?) - the rudiment of the
nictitating membrane of birds, the membrana niclilans.

74

HUMAN ANATOMY.

The point of reflection is called the fornix conjunctivae,
and the reflected portions the superior and inferior palpebral
folds.

The lachrymal apparatus (apparatus lacrimalis) consists of
the lachrymal gland, canals-, sac and nasal duct.

The lachrymal gland (glandula lacrimalis) is an oval,
glandular body, about the shape and size of an almond, sit-
uated in a depression in the upper surface of the orbit near
the external angular process.

The anterior portion of the gland is sometimes described

ducts' of/
lachrymal,

GLAND

CARUNCLE
I CANALICULUS

LACHRYMAL SAC

NASAL DUCT

Fig. 135.
The lachrymal apparatus. (Gerrish, after Testut; EcMey.)

as a separate lobe — the palpebral portion of the gland, or
accessory gland of Eosenmiiller (glandula lacrimalis inferior) ;
the back part of the gland is designated the superior lachrymal
gland (glandula lacrimalis superior).

The gland is attached to the bony roof of the orbit by the
tarso-orbital fascia.

The ducts, seven to ten in number, open upon the con-
junctiva near its point of reflection by minute orifices arranged
in a row.

The laclirymal canals commence at the puncta lacrimalia,
at the summits of the lachrymal papilla (carunculus lacrimalis),
and descend by two canaliculi to empty into the lachrymal sac.

The superior canal (ductus lacrimalis superior) descends
obliquely inward and downward, while the inferior (ductus

ORGANS OF SPECIAL SENSE. 375

lacrimalis inferior) descends at first and then passes nearh
horizontally inward.

The lachrymal sac (saccus lacrimalis) is the oval,
dilated, upper portion of the nasal duet, lodged in a deep groove
formed by the nasal process of the superior maxilla and the
lachrymal bone. It is crossed by the tensor tarsi muscle, which
acts as a compressor, and receives a fibrous expansion from the
tendo oculi.

Its structure is made up of a fibrous elastic coat, lined bv
mucous membrane continuous with the nose and conjunctiva.

The nasal duct {ductus nasolacrimalis) is a membranous
tube about three-quarters of an inch in length, extending from
the lachrymal sac to the inferior meatus of the nose, and lining
the bony lachrymonasal canal. It passes backward, downward,
and outward, and is protected at its inferior extremity bv a
valve of mucous membrane — the valve of Hasner (plica lacri-
malis \ Hasneri]).

The mucous lining is continuous with that of the sac, hut
instead of having squamous epithelium it is ciliated in the duct,

THE EAR.

The ear (organon a ud it us) — the organ of hearing — is
contained in the petrous and mastoid portions of the temporal
hone, and consists of three divisions, — external ear, middle ear
or tympanum and internal ear or labyrinth: —

or meatus;

1. External ear, ( Auricle or pinna.

I. External auditory canal

f Membrana tympani,

2. Middle ear o'r tympanum, J Tyn.pai.ic cavity.

' ', .Mastoid sinuses.

(_ Eustachian tube;

{Vestibule,
Semicircular canals,
Cochlea ;
■>. internal ear or j

labyrinth. \ r TT, . ,

[ Utricle,

I Membranous portion. \ Saccule,

1 semicircular canals.
I Cochlea.

The external ear includes two parts, the auricle and the
external auditory canal.

376 HUMAN ANATOMY.

AURICLE (AURICULA), OR PINNA.

The external prominent portion is composed of cartilagin-
ous segments, connected together by ligaments and muscles
richly supplied with blood vessels, nerves, and lymphatics, and
covered with skin. It presents the following elevations and
depressions : —

Fossa of the helix, a depression between the helix and anti-
helix ;

Fossa of the antibelix (fossa triangularis [auricula]), a
depression above the bifurcation of the antihelix;

Tragus, the prominence in front of the concha, usually cov-
ered with hair;

Antitragus, a small, conical eminence behind the tragus,
from which it is separated by the incisura intertragica ;

Lobule (lobulus auricula), the soft, rounded portion de-
pending below the antitragus;

Concha, a deep cavity, surrounded by the helix, leading into
the external meatus.

Muscles. — The muscles of the auricle include two sets, the
extrinsic muscles, already described (vide Muscles), of which
there are three — the attolens aurem, attrahens aurem and re-
trahens aurem — and the intrinsic muscles, but slightly devel-
oped, of which there are two sets, four on the anterior surface
of the auricle-^-the tragicus (m. tragicus), antitragicus (m.
antitragicus) , helicis major (m. heHcis major), and helicis
minor (m. helicis minor) — and two on the posterior surface,
transversus auriculae (m. transversus auricula3) and obliquus
auriculae (m. obliquus auricula').

Arteries, auricular branch, from the occipital; posterior
auricular, from the external carotid; and anterior auricular,
from the temporal. The- veins correspond to the arteries.

Nerves, auricular branch, from the pneumogastric ; auric-
ulotemporal branch, from the inferior maxillary; occipitalis
major and occipitalis minor; auricularis magnus, from the
cervical plexus; and posterior auricular, from the facial.

Auditory caxal, or meatus auditorius externus (meatus
acusticus externus), is an osseocartilaginous canal, about one
and one-fourth inches in length, extending from the concha to
the tympanic membrane.

The osseous portion (pars ossea tuba auditivce, or semi-
canalis tuba, auditivce) forms about two-thirds of the passage,
and consists in greater part (anterior and lower) of a curved
plate of bone — the annulus tympanicus.

ORGANS OF SPECIAL SENSE.

377

The anterior and upper part of the ring presents two spines
— spina tympanica, major and minor — for the Ligaments of the
malleus.

The sulcus tympanicus is a furrow on the inner edge of
the ring, for the attachment of the tympanic membrane.

The cartilaginous portion (pars cartUaginea tuba' audi-
tiva ) forms about one-third of the passage, and consists of the
inverted cartilage of the tragus and concha, the upper and back
part of which is deficient, the cleft being filled with fibrous
tissue.

Fig. 136.

rnal, middle, and internal ear. 1, external ear; 2, middle ear:
•",, internal ear: 4. pinna; 5. helix; 0, antihelix; 7 fossa naviculars;
s. fossa innominata; 9, tragus; 10, antitragus: 11, concha; 12, lobe;
I .;. meatus auditorius externus; 14, tympanic membrane; 15, promon-
tory: in, foramen rotundum; 17, posterior wall of the tympanum; is,
OBSlcula auditus; 19, Eustachian tube; 20, narrow canal; 21, vestibule:
22. semicircular canals, the superior, posterior, and horizontal; 23,
ampullae, 21. cochlea; 26, prominence caused by the scala vestibuli;
20, scala tympani. (Boenning.)

The canal, including the tympanic membrane, is lined
throughout with skin, containing short hairs, vascular papilla',
sebaceous and ceruminous glands (glandvXai ceruminosw) .

Arteries — branches of the internal maxillary, posterior
auricular and temporal branches of external carotid.

Nerves from the auriculotemporal branch, the inferior
maxillary and auricular branch of the pneumogastric.

378 HUMAN ANATOMY.

MIDDLE EAR (aURIS MEDIA), OR TYMPANUM,

is an irregular cavity (cavum tympani) , situated between the
auditory canal and the labyrinth, communicating with the
pharynx through the Eustachian tube, and also with the mas-
toid cells. It contains a chain of movable bones, part of the
chorda tympani nerve, and is filled with air. Its average diam-
eters are about half an inch in height and width, and a line or
two in depth from without inward. It is lined with mucous
membrane, continuous with that of the Eustachian tube and
mastoid cells, and which is reflected over all the tympanic con-
tents. It is bounded by a roof, floor and four walls, which
present the following points : — ■

Eoof (paries tegmentalis) , a very thin plate of bone {teg-
men tympani), separates the tympanum from the cranial cav-
ity, and corresponds to a depression on the anterior wall of the
petrous bone;

Floor (paries jngularis), forms the bottom of the jugular
fossa, and presents: —

The opening for Jacobson's nerve, the tympanic branch of the
glossopharyngeal ( n. tympanicus ) .

Outer wall, formed by the tympanic membrane, Shrapnell's
membrane, and the annulus tympanicus surrounding it: —

Notch of Rivinus (incisure/, tympanica [Rivini]), incomplete upper
ring of bone;

Iter chordae posterius (canaliculus chordce tympani), gives en-
trance to chorda tympani nerve;

Iter chorda* anterius, or canal of Huguier, gives exit to same;

Glaserian fissure (fissura petrotympanica [Glaseri]), above and in
front of annulus tympanicus, receives the anterior ligament of the mal-
leus, the long process of the malleus, and the tympanic artery;

Pouches of the membrama tympani, are two or three pockets
formed by the doubling of the mucous membrane around the chorda
tympani nerve.

Inner wall (paries labyrinthica) , separates the tympanum
from the labyrinth : —

Fenestra ovalis (fenestra vestibuli) , an oval window, leading to
the vestibule, closed by the membrane to which the base of the stapes
is attached;

Fenestra rotunda (fenestra cochlea?), .a round window, leading to
the scala tympani, but closed also by a membrane — membrana tympani
secundaria.

Promontory (promontorium) , two grooves,, marking the first turn
of the cochlea, and separating the fenestras ovalis and rotunda;

ORGANS OF SPECIAL SENSE. 379

Rounded eminence of the aqueductus Fallopii (prominentia canaiis
facialis), a small conical eminence above the fenestra ovalis, which con-
tains within it the aqueductus Fallopii, the long- canal for the facial
nerve.

Posterior wall (paries mastoidea) : — ■

Openings of tfo mastoid cells, three or four in number, connect
these sinuses with the tympanum.

Anterior wall (paries carotica), is a thin plate of bone,
which separates the tympanum from the carotid canal.

Openings of the canal for tensor tympani (semicanalis m. Icnsoris
tympani), lies above and parallel with the canal for the Eustachian tube,
and transmits the tensor tympani muscle;

Opening of Eustachian tube (tuba auditiva [Eustachii ] ) , the
larger of the two, is separated from the former by a thin plate of bone,
the processus cochleariformis (septum canaiis musculotubarii) .

The tympanum is divided into two parts — the attic (re-
cessus epitympanicus) of the tympanum and the atrium. The
former is situated on a plane directly above the atrium, and is
bounded above by the tegmen, externally by auditory plate, and
internally by prominence of the tympanum. On the outer part
of the attic is a smooth surface called the scute (Leidy).

The Eustachian tube (tubce auditiva \ Eustachii]) is an
osseocartilaginous canal, one and one-half to two inches in
length, extending from the tympanum to the pharynx.

It is about one-third osseous and two-thirds cartilaginous,
and lined with ciliated epithelium continuous with the pharynx
and tympanum. Its pharyngeal orifice is trumpet-shaped, and
opens at the side of the pharynx, behind the inferior meatus.

Muscles of the Eustachian tube: —

Tensor palati (m. tensor veil palatini), the most important
has been described [vide Palatal Region). Its action is to pull
tin' anterior wall of the tube outward and downward, and widen
the canal.

Internal Pterygoid {vide Muscles). — Some fibers are in-
serted into the floor of the tube. It net- as tensor of the fascia.

lAgamenta salpingopharyngeal, arises from the superior
and middle constrictors nf the pharynx, and is inserted by three
to five tendinous cords into the pharyngeal orifice of the tube.

Action, opens the tube.

Arteries of Eustachian Tube. — Pharyngeal from the exter-
nal carotid, middle meningeal from the internal maxillari ami

-mall branches from the internal carotid.

380 HUMAN ANATOMY.

Nerves, by branches from the glossopharyngeal, inferior
maxillary, otic ganglion and facial nerve.

Membrana tympani is a thin, parchment-like membrane,
stretched upon the annulus tympanicus, forming the bottom of
the external auditory canal, and separating it from the tym-
panum. It is placed obliquely downward and inward at an
angle of 45°.

Structure. — Its three layers are :—

External or cuticular, derived from the skin of the meatus;

Middle or fibrous, consisting of two sets of fibers, radiating
and circular, the latter forming a tendinous ring around the
margin ;

Internal or mucous, continuous with the mucous membrane
of the tympanum.

Its outer surface presents : —

Manubrium of malleus, projecting downward and back-
ward ;

Processus gracilis of malleus, projecting outward above the
manubrium ;

Umbo (umbo membrance iympance), a depression of the
membrane formed by the lower end of the manubrium;

Yellow spot, the cartilaginous end of the manubrium;
pyramid of light, a triangular cone of reflected light in the
antero-inferior quadrant of the membrane.

Inner surface (vide Outer Wall of Tympanum).

Arteries, tympanic branch of inferior, branch from the
internal carotid.

Nerves, from the superficial temporal branch of the tri-
facial and from the tympanic plexus.

OSSICLES OF THE TYMPANUM (OSSICULA AUDITUS).

The small bones of the tympanum are three in number,
and connect the membrana tympani with the membrane closing
the fenestra ovalis. They are the

1. Malleus, or hammer, consists of a head (capitulum
mallei), neck (collum mallei), manubrium or handle, processus
gracilis (processus anterior \Foli%\), and processus brevis (pro-
cessus lateralis). The manubrium (manubrium mallei) is at-
tached to the membrana tympani, and has the tendon of the
tensor tympani attached. Processus gracilis is lodged in the
Glaserian fissure.

2. Incus, or anvil, consists of a body (corpus incudis) and
a long (eras longum) and short processes (crus breve). The

ORGANS OF SPECIAL SENSE. 381

bodv articulates with the malleus and the long process by means
of a rounded process. The os orbiculare (processus lenticularis)
articulates with the head of the stapes.

3. Stapes, or stirrup, has a head (capitvlwm stapedis),
neck, two branches or crura (crura anterius et crura poste-
riiis). which unite into a cross-piece or bast' (basis stapedis)
The neck has inserted into it the stapedius muscle, and the base
is fitted to the fenestra ovalis.

Fig. 137.

The auditory ossicles. A. G., external meatus; M, membrana tym-
pani ; n, handle of the malleus and its short process (p); h, head of
the malleus; a, incus; K, its short process, with its ligament; I, long
process; *, os orbiculare; »S', stapes; -lJ", Ax, the axis of rotation of
the ossicles, shown in perspective; t, line of traction of the tensor
tympani. The other arrows show the movements of the ossicles when
the tensor contracts. (Boennhnj.)

Ligaments of the ossicles (ligamenta ossiculorum audi-
tus) : —

Anterior ligament of the malleus (ligamentum mallei anterius),
extends from the neck of the malleus to the outer wall of the tympanum;

Superior Ligament of the malleus — ligamentum mallei sus|icn-
sorium [ligamentum mallei superius), suspends the head of the malleus
to tin- roof;

Posterior ligament of the incus (ligamentum incudis posterius),
attaches the shorl process to the posterior wall;

Superior ligament of the incus (ligamentum incudis superius),
]- merely ■■> told of mucous membrane; while tin- inner surface ami cir-

382 * HUMAN ANATOMY.

cuniference of the base of the stapes is connected to the margin of the
oval window by means of the annular ligament of the stapes (ligamen-
tum annulare baseos stapedis) .

Muscles. — The tensor tympani and stapedius.

Tensor t}rmpani (already described).

Stapedius (m. stapedius) arises from the hollow of the
pyramid on the inner wall, and its tendon is inserted into the
neck of the stapes. It is the smallest muscle in the human body.
Nerve from the tympanic branch of facial.

Arteries: —

Tympanic branch of internal maxillary;
Stylomastoid branch of posterior auricular;
Petrosal branch of middle meningeal;
Tympanic branch from internal carotid;
Branch from ascending pharyngeal.

Veins accompany the corresponding arteries and empty
into middle meningeal and pharyngeal.

Nerves: —

Chorda tympani, from the facial, enters the iter chorda?
posterius, crosses the tympanum between the long process of
the incus and the handle of malleus, and makes its exit at the
iter chordae anterius;

Tympanic branch of glossopharyngeal (Jacobson's nerve)
enters the floor, supplies the fenestras and mucous membrane of
tympanum and Eustachian tube ;

Tympanic branch from facial to the stapedius;

Branch from the otic ganglion to the tensor tympani.

The tympanic plexus is formed upon the surface of the
promontory, from the following nerves: — ■

Jacobson's nerve, tympanic branch of the glossopharyngeal;
Branch of the superficial petrosal, from the facial;
Branches from the carotid plexus of the sympathetic.

INTERNAL EAR, OR LABYRINTH.

The internal ear (auris interna), the essential part of the
organ of hearing, consists of three complex cavities within the
petrous portion of the temporal bone, rilled with fluid, the
perilymph, and containing a membranous sac filled also with
fluid, the endolymph, which receives the distributions of the
auditory nerve.

ORGANS OF SPECIAL SENSE. 383

Its divisions are : —

(Vestibule,
Semicircular canals,
Cochlea ;

f Utricle,

, ,. i Saccule,

Membranous portion, <j 8emicircular canals>

[ Cochlea.

Vestibule (vestibulum) , is a common cavity of communi-
cation between the bony parts of the internal ear. It is sit-
uated between the tympanum without, the cochlea behind, and
tli. semicircular canals in front, and measures one-fifth of an
inch in its anteroposterior and vertical diameters, and less from
without inward. It presents: —

Fenestra ovalis (fenestra vestibuH) on its outer wall, closed
by the stapes and its ligament;

Fovea hemispherica (recessus spharicus) , a circular de-
pression on its inner wall for the saccule, and perforated by
the macula cribrosa (macula cribrosa media), for the vestibular
filaments of the auditory nerve;

Orifice of the aqucechictus vestibular, on the inner wall for
the transmission of a small vein;

Eminent ia pyramidalis, a vertical ridge on the inner wall
separating the two fovea?.

Fovea semielliptica (recessus ellipticus), in the roof lodges
the utricle.

SemicircuIiAB canals (canales semicirculares ossei) are
three canals, forming each two-thirds of a circle, one-twentieth
of an inch in diameter, and named, from their position, the
superior, posterior and external. They are placed nearly at
right angles to each other and open into the vestibule by live
apertures — two extremities uniting to form one.

The superior (canalis semicircularis superior) and poste-
rior {canalis semicircularis posterior) arc both vertical, the
former being more anterior.

The externa] {canalis semicircularis lateralis) is placed
horizontally, its arch directed backward.

Ampulla, arc the dilated, flask-shaped extremities of the
tubes, and aro about one-tenth of an inch in diameter.

Tin: cochlea resembles closely a common snail's shell,
placed with the base corresponding to the bottom of the meatus
auditoriue internus, and its apes directed outward and forward.

It consists of two parallel tubes one and one-half incbes in

384

HUMAN ANATOMY.

length, one-tenth of an inch in. diameter, wound spirally for
two and one-half turns around a central pillar — the modiolus.

The modiolus, or columella (basis modioli), is broad at the
base, but tapers gradually toward the apex, where it terminates
within the last turn or cupola in the infundibulum, a funnel-
shaped lamina of bone. Its interior is traversed by numerous
canals for vessels and nerves, one of which — the canalis centralis
modioli — runs nearly the whole length and transmits the
arteria centralis modioli.

■ FIG. 138.

Organ of Corti. AT, cochlear nerve; K, inner and, P, outer hair-
cells; n, nerve fibrils terminating in P; a, a, supporting cells-; d, cells
in sulcus spiralis; z, inner rod of Corti; Mb, Corti, membrane of Corti,
or the memibrana tectoria; o, the membrana reticularis; H, O, cells
filling up the space near the outer wall. (Bocnning.)

Lamina spiralis, the partition between the two tubes, con-
sists of two thin laminas of bone filled with cancellous tissue —
lamina spiralis ossea — projecting from the modiolus half-way to
the outer wall, the lamina being completed by the membrana
basilaris. The osseous lamina terminates in the cupola in a
hook-like process — the hamulus (hamulus lamince spiralis).

The spiral canal, between the modiolus and the outer wall,
is divided by the lamina spiralis ossea and membrana basilaris
into two canals, or scalce — the upper scala vestibuli, and the
lower scala tympani.

ORGANS oF SPECIAL SENSE. 335

The first turn of the spiral canal presents three openings : —

1. Fenestra rotunda, a circular aperture communicating
with the tympanum, and closed by the membrana tympanum
secundaria.

'2. Fenestra oralis, an oval opening, communicating with
the vestibule.

:'.. Aquaeductus cochlearis (apertura externa canaticuli
cochlea), a Bmall foramen opening on the inferior surface of the
petrous portion of the temporal bone, and transmitting a small
vein from the cochlea to the jugular vein.

8cala vestibuli, begins at the fenestra ovalis, and ascends
in a spiral course above the lamina spiralis and membrana
basilaris, to communicate with the scala tympani, through the
helicotrema within the vestibule. It contains perilymph.

Scala tympani begins at the fenestra rotunda, and ascends,
in a spiral course below the scala vestibuli, from which it is
separated by the osseomembranous lamina. It also contains
perilymph.

11 1'licotrema is an opening within the cupola, by which the
two scalae communicate. It is formed by a deficiency of the
osseous lamina.

Canalis spiralis modioli is a small canal which winds
around the modiolus at the attachment of the osseous laminae.
Jt contains a gangliform swelling — ganglion spirale (ganglion
spiral e cochlea) — from which nerves pass to the organ of Corti.

The membranous labyrinth (labyrinthus membrana-
n us) corresponds closely to the osseous, the vestibule consisting
of two membranous sacs — the utricle and saccule — communicat-
ing with each other, and the former receiving the five openings
of the membranous semicircular canals, the latter communicat-
ing with the membranous cochlea through the canalis reuniens
(il ml us reuniens \IIenseni\). The membranous labyrinth is
Burrounded everywhere with perilymph (perilympha) } filled with
endolymph (endolympha | . and is composed of three coats — an
outer fibrous layer, middle or tunica propria and inner epithe-
lial Iay<r.

Utricle {utriculus), the larger of the two, is an elliptical
sac lodged in the fovea hemielliptica. The semicircular canals
communicate with it by five openings. Its wall is flic thickest
near tin- crista vestibuli, where the filaments of the nerve enter,
the macula acustica.

Saccule (sat ruins) . is a bcniispberical sac lodged in the

fiemispherica. It communicates with the cochlea through

a Bmall duct the canalis reunicn-.

386 HUMAN ANATOMY.

The otoliths, or otoconia, are small masses of crystals of
lime carbonate, contained in the inner wall of the ntricle and
saccule opposite the distribution of the nerves.

Semicircular Canals (ductus semicircular es) . — These are
three membranous tubes corresponding exactly in shape, num-
ber and form with the bony canals in which they are contained. <
They are surrounded everywhere with perilymph, except at the
ampullae, where they are in contact with the bony canals. The
inner, or epithelial, layer of the membrane in the ampullae is
covered with columnar ciliated epithelium — auditory hairs.

The membranous cochlea begins at the base and ascends
in a spiral course within the osseous cochlea to terminate in the
cupola. It includes only the canalis cochlea? — a part of the
scala vestibular. As before stated, the membrana basilaris ex-
tends from the margin of the lamina spiralis ossea to the outer
wall of the cochlea, dividing the cavity into the two scalas — the
scalae vestibular above, the scalae tympani below. The former is
again subdivided by the membrane of Keissner (membrana
vestibularis [Reissneri]) into two parts, the outer of which
forms the canalis cochlear, or scala media— the, membranous
cochlea proper — on the floor of which is the organ of Corti
(organon spirale [Cortii~]) covered by the membrana tectoria.
The scalae are lined with periostium and filled with perilymph.
The scala tympani ends at the fenestra rotunda, but the scala
vestibula communicates freely with the vestibula.

Limbus lamina? spiralis is the periosteal margin of the
lamina spiralis ossea, and consists of an upper lip — the labium
vestibulare — and a lower lip — the labium tympanicum — sepa-
rated by a groove — the sulcus spiralis.

Membrana basilaris extends from the labium tympanicum
to the outer cochlear wall, to which it is attached by the liga-
mentum spirale of Henle.

Membrane of Beissner arises from the middle of the vestib-
ular lamina and passes obliquely at an angle of 40 degrees to
the outer cochlear wall, separating the canalis cochleae from the
scala vestibula.

Canalis cochlea? extends as a spiral sac closed at both ends
through the osseous cochlea, and contains the most important-
part of the labyrinth — the ultimate distribution of the auditory
nerve in the organ of Corti. It is triangular on section, the
membrana basilaris forming the base, the membrane of Eiessner
the inner side, and the periosteum of the cochlea its outer side.

Membrana tectoria, or membrane of Corti, is attached to
the vestibular surface of the spiral lamina, in close proximity to

ORGANS OF SPECIAL SENSE. 387

the attachment of the membrane of Reissner, and arches over to
the outer cochlear wall, inclosing- the organ of Corti, but not in
contact with it.

Organ of Corti consists of two sets of pillars — the inner
and outer rods of Corti — extending upward upon the vestibular
surface of the membrana basilaris, and forming a series of
arches. Between the bases of the arches is the zona arcuata.
There are over three thousand arches, and within them is
formed a tunnel extending the entire length of the lamina
spiralis terminating at the hamular process.

Inner roils of < 'urfi rest upon the basilar membrane. Their
upper extremities resemble the proximal extremity of the ulna,
and each has on its inner side a row of epithelial cells — the
inner linir cells.

Outer rods of Corti are attached in a similar manner at
the bases, and their extremities each resemble the head and bill
of a swan, the former fitting into the cavity in the inner rods.
On the outer side are four rows of ciliated, cells — the outer hair
cells.

Reticular membrane, lamina reticularis or membrane of
Kolliker, is a delicate complex network of phalanges — fiddle-
shaped structures — extending from the inner rods to the ex-
ternal row of the outer hair cells.

Tut; internal auditort canal is a short canal about
one-third of an inch in length, extending outward from the
meatus auditorius interims (meatus acustiens internus), on the
posterior Burface of the petrous portion of the temporal hone.
to terminate at a vertical, perforated plate — the lamina crih-
rosa. This plate is divided by a horizontal ridge — the falciform
cresl {crista falciformis) — into a lower and upper portion. The
lower is perforated by numerous foramina for passage of the
auditory artery and branches of the auditory nerve, some of
which are arranged into a spiral-shaped depression, called the
tracius spiralis foraminosus; the upper has one large open-
ing-—the commencement of the aqueductus Fallopii (canalis
facialis) for portio dura, or seventh nerve.

Auditory Nerve (n. acusticus). — The auditory nerve enters
die internal auditory meatus in company with the facial, and
:it the bottom divides into two branches — the vestibular and

sochlear.

Vestibular nerve (n. vestibularis) subdivides into three
branches, as follow

Superior, distributed <<> the utricle and ampullae of the superior
find external semicircular canals;

388 HUMAN ANATOMY.

Middle, enters the bottom of the fovea hemispherica, and is dis-
tributed to the saccule; and the

Inferior is distributed to the ampulla of the posterior simicircular
canal.

Cochlear nerve (n. cochlearis) , ascends in the canals in the
modiolus, and divides into numerous branches which pass be-
tween the plates of the lamina spiralis ossea, forming a plexus
which contains the ganglia spirale (ganglion spirale), from
which filaments are distributed to the outer and inner hair
cells of the organ of Corti.

Arteries, of Labyrinth: —

Internal auditory, from the basilar, divides into vestibular
and cochlear branches., which accompany the corresponding
nerves ;

Stylomastoid, from the posterior auricular, enters through
the stylomastoid foramen.

THE TONGUE.1

The tongue (lingua) is the organ of the sense of taste, and
lies in the floor of the mouth. It is composed of a mass of
muscles, the free surface of which is entirely invested with
mucous membrane. It consists of three parts: —

Base, or root (radix Ungues), attached to the hyoid bone,
the epiglottis and the soft palate;

Body (corpus linguae), the back or dorsum of which is
marked by a median line or raphe, terminating behind in
a cavity— the foramen cecum (foramen caecum lingua? [Mor-
gagnii]).

Apex (apex lingua?), or tip, narrow and pointed, directed
forward.

The mucous membrane (tunica mucosa Ungual) resembles
skin, consisting of a corinm or mucosa, containing numerous
papilla?, and covered with epithelium. The papilla? (papilla?
lingua?) are most numerous over the anterior two-thirds of the
dorsum, and consist of three varieties : —

Circumvallate or papilla? maxima? (papilla? vallata?) , the
largest, about ten in number, about one-twelfth inch wide, are
arranged at the back part of the dorsum like the letter V with
the apex directed backward;

Fungiform or papilla? media? (papilla? fungiformes et
papilla? lenticulares) , the medium, are scattered over the organ,
especially at the tips and sides;

1 Vide Lingual Muscles, page 135.

ORGANS OF SPECIAL SENSE. 389

Filiform, conical or papillae minima3 (papUlce conicce et
papilla fUiformes), the smallest, are distributed over the ante-
rior two-thirds of the dorsum.

Mucous and serous glands and simple papilla?, such as are
found in the skin, are also present.

Taste buds, minute, flask-shaped bodies, about one-three-
hundredths of an inch in length, are situated in the circumval-
late and fungiform papilla.

Arteries are branches of the lingual, facial and ascending
pharyngeal.

1. Nerves. — Hypoglossal, the principal motor nerve.

2. Lingual branch of glossopharyngeal, the special nerve of
taste.

3. Lingual branch of the trifacial, to sides and anterior
part; nerve of common sensation.

4. Chorda tympani, probably nerve of special sense.

5. Superior laryngeal, filaments from its internal branch
to the base.

THE SKIN AND APPENDAGES.

The skin (integumentum commune), besides being the spe-
cial organ of the sense of touch, is an absorbing and excretory
organ, and protects the underlying structures.

It consists of two layers — the epidermis or cuticle, and the
derma or true skin. The appendages are the nails, hair, sudorif-
erous and sebaceous glands, and their ducts.

The epidermis, or cuticle, is an epithelial structure con-
sisting of four layers : —

1. Bete MalpigTm, the deepest layer, in contact, with the corium, is

composed <>f several layers of round or polyhedral epithelial cells. This
layer is pigmented in the negro and other dark races.

2. Granular layer, is a single layer of compressed, spindle-shaped
cells.

'■',. St rut am I uciilii m . is -till mure (-(impressed into scales.
4. Stratum corneum, several layers of horny scales.

The derma, corium, or true skin, has two Layers, the reticular
or deeper, and the papillary or superficial.

Reticular layer {stratum reticulare) is composed of inter-
lacing bands of white fibrous tissue, mixed with yellow elastic
libers, and some iinstrialed muscular fibers where hairs are
found, together with blood vessels, lymphatics and nerves.

Papillary layer (stratum papUlare) is covered with minute,
vascular, highly sensitive elevations- the papillae — from one-
one-hundredth to one-two-hundred-and-fiftieth of an inch in

390 HUMAN ANATOMY.

diameter. These papillae are in places arranged into parallel
curved ridges, and have in the most sensitive situations some
one of the peripheral end organs (already described) added
to their structure.

Nails (ungues) are horny plaques of modified epidermis,
firmly adapted to the derma on the dorsal surfaces of the
termiual phalanges. Each nail is firmly implanted by its root
(radix unguis) into a fold of skin.

The matrix (matrix unguis) is the derma beneath the
body, which is vascular and highly sensitive.

The lunula,, on account of its crescentic shape, is the white,
less vascular portion of the matrix near the root.

Haies (pili) are a cylindrical' modification of the epider-
mis, and consist of a root imbedded in the skin, a shaft and a
point.

Eoot (radix pili) is lodged in a pouch-like involution of
epidermis — the hair follicle (follicidus pili). This is composed
of an inner or cuticular and an outer or dermic layer, and pre-
sents at the bottom a vascular papilla, on which the hair rests,
and from which it grows.

Shaft (scapus pili) consists of a pith or medulla (sub-
stantia medullaris pili) in the center, surrounded by a fibrous
part containing pigment, and covered with a layer of scaly
epithelium.

Point contains the two latter elements, but has no medulla.

Sebaceous glands (glandulce sebacece) are minute, gland-
ular bodies, situated in the substance of the corium, and each
opening by a single duct into a hair follicle, or upon the sur-
face of the skin. They are most abundant where hairs are
found. The Meibomian glands in the eyelids are the largest.

Sudoriferous or sweat glands (glandulce sudoriferce) are
minute, reddish, glandular bodies, situated usually in the sub-
cutaneous connective tissue, each consisting of a single con-
voluted tube. Each gland opens on the surface of the skin.

SURGICAL ANATOMY.

THE TRIANGLES OF THE NECK.

The general outline of the neck is somewhat quadrilateral.
Bounded in front by the median line, behind by the trapezius
muscle, above by the lower border of the body of the maxilla
and below by the clavicle. It is divided by the sternomastoid
muscle running obliquely through it into two large triangles,
an anterior and a posterior triangle. These are again sub-
divided by the crossing of the omohyoid muscle into two smaller
triangles each. The anterior into the superior and interior
carotid triangles, and the posterior into the occipital and sub-
clavian triangles. The digastric nmscle, at the upper part ot
the anterior triangle, separates a triangular space called the
submaxillary triangle. n„«™.

The (interior triangle of the neck is bounded as follows.—
Front, median line of the neck ;

Behind, anterior border of the sternomastoid muscle ;
Vl.uve. lower border of the body of the lower jaw and a
line from its angle to the mastoid process, forming the base ot
the triangle; .

Below, the top of the sternum, forming the apex.
The floor is formed by the sternohyoideus, sternothy-
riodeus, thvrohvoideus, inferior and middle constrictors of the
pharynx, the anterior belly of the digastricus, the mylohyoideus,
stylonyoideus, and hyoglossus muscles. The roof is formed by
the skin, superficial fascia, platysma myoides, and deep iascia.

The inferior carotid triangle is the most inferior subdivi-
sion of the anterior triangle, and is bounded as follows:—
Front, median line of the neck;
Behind, anterior border of the sternomastoideus ;
Above, anterior belly of the omohyoideus;
Below, the apex of "the anterior triangle.
It contains the following structures:—
Thyroid gland and lower part of the trachea and Larynx;
Inferior thyroid and common carotid arteries;
Inferior thyroid and internal jugular reins;
Pneumogastric, recurrenl laryngeal, descendens noni, com-
municans noni and sympathetic nerves.

(391)

392 HUMAN ANATOMY.

The superior carotid triangle is the middle subdivision of
the anterior triangle of the neck, and has the following bound-
aries : —

Above, posterior belly of the digastricus;

Below, anterior belly of the omohyoideus;

Behind, anterior border of the sternomastoideus.

It contains the following structures : —

Termination of the common carotid;

The internal carotid;

The external carotid, and the following branches: —

Superior thyroid, lingual, facial, ascending pharyngeal
and occipital;

The internal jugular vein, and the following tributaries : —

Lingual, facial, superior thyroid, pharyngeal and occa-
sionally the occipital;

The pneumogastric, superior laryngeal, external laryngeal,
descendens noni, spinal accessory, hypoglossal and sympathetic
nerves.

The submaxillary triangle is the most superior of the sub-
divisions of the anterior triangle, and has the following bound-
aries : —

Above, the lower border of the body of the jaw and the
imaginary line behind ;

In front, the median line of the neck ;

Behind, the posterior belly of the digastricus.

It contains the following structures : —

External carotid, internal carotid, facial, submental, mylo-
hyoidean arteries;

The internal jugular, the commencement of the external
jugular, branches of the anterior jugular and the facial vein
and its branches;

The inframaxillary branches of the facial nerve, the ascend-
iug branches of the superficial cervical nerve, and the pneumo-
gastric and glossopharyngeal and mylohyoid nerves;

Portions of the parotid and submaxillary glands, and also
submaxillary lymphatic glands and vessels.

The posterior triangle of the neck occupies the space be-
hind the posterior border" of the sternomastoideus, and is
bounded as follows : —

Front, posterior border of the sternomastoideus;

Behind, anterior border of the trapezius;

Below, upper border of the middle third of the clavicle,
forming its base;

Above, the occiput, forming the apex.

SURGICAL ANATOMY.

393

Its floor is formed from above downward, by the following
muscles : —

Splenius capitis, levator anguli scapuli, scalenus medius,
scalenus posticus, and the upper portion of the serratus magnus.

Its roof is formed by the superficial and deep fascia and
below by the platysma myoides.

FIG. 139.
Triangles of the neck. (Bocnning.)

It contains the following structures: —

'Jdic transversalis colli artery and vein;

Spinal accessory and superficial plexus of the cervical
nerve ;

Lymphatic glands and vessels.

The subclavian triangle, or the inferior division of the
posterior triangle, is bounded —

394 HUMAN ANATOMY.

In front by the margin of the sternomastoideus, behind by
the posterior belly of the omohyoideus, below by the clavicle.

It contains the following structures : —

The subclavian, transversalis colli and transversalis humeri
or suprascapular arteries;

The transversalis colli, suprascapular and external jugular
veins ;

The descending branches of the superficial cervical plexus
and the brachial plexus of nerves ;

Lymphatic nerves and vessels.

Triangle in Front of the Elhoiu-joint.

Bounded —

Externally, by supinator longus;

Internally, by pronator radii teres;

Base, above, by a line (imaginary) drawn through the con-
dyles;

Apex, below, by crossing of supinator longus and pronator
radii teres.

It is covered in by skin, superficial fascia and bicipital
fascia; the floor is formed by oblique fibers of the supinator
brevis and lower part of brachialis anticus muscles.

It contains: —

From within outward, median nerve, brachial artery,
vense comites, biceps tendon and musculospiral nerve.

Scarpa's Triangle (trigonum femorale)

is a large triangular space situated in the upper part of the
anterior surface of the thigh, through which the femoral vessels
descend. It is bounded —

Externally by sartorius, internally by adductor longus,
above by Poupart's ligament; below, apex is formed by crossing
of bounding muscles.

It is covered in by skin, superficial fascia, cribriform fas--
cia and fascia lata, and its floor is formed by the following from
without inward : iliacus, psoas, pectineus and portion of adduc-
tor brevis muscles.

It contains: — ■

The femoral artery (with its profunda and cutaneous
branches), inclosed in the femoral sheath, femoral vein (joined
by profunda and long saphenous veins), anterior crural nerve
and its branches [from within outward being vein, artery and
nerve], deep lymphatic glands and vessels and adipose tissue.

SI RGICAL ANATOMY.

395

Axilla.

This is a pyramidal space between the upper and lateral

part of the chest and the inner side of the arm. It is bounded —

In front, by the pectoralis major and minor muscles; be-

FIG. 140.

The axilla. 1, axillary artery; 2, brachial artery; 3, acromio-
thoracic artery; 4, superior thoracic artery; 5, subscapular artery; 6,
dorsalis scapulae artery; 7, posterior circumflex atery; 8, superior pro-
funda artery; 9, posterior thoracic nerve; 10, long subscapular nerve;
11, median nerve; 12, cephalic vein; 13, musculocutaneous nerve; 14,
teres major muscle. {Boenning.)

hind, by latissimus dorsi, teres major und Bubscapularis; inter-
nally, by the upper four ribe and intercostal and upper pari of

serratlM magnilfl muscles, and ils apex i- directed upward, and

396 HUMAN ANATOMY.

is formed by the space between the first rib, clavicle and upper
border of the scapula, and its base by the skin and axillary
fascia stretched across between the lower borders of the pec-
toralis major and latissimus dorsi muscles.

It contains: —

The axillary artery and vein and their branches; the
brachial plexus of nerves and the branches given off below the
clavicle; branches of the intercostal nerves; ten or twelve lym-
phatic glands and a quantity of loose adipose and areolar tissue.

Popliteal Space.

The popliteal space is a lozenge-shaped space situated at
the back of the knee, and forms the ham. It is bounded —

Externally, above the joint, by the biceps; below the joint,
by outer head of gastrocnemius and plantaris; internally, above
the joint, semitendinosus, semimembranosus, gracilis and sar-
torius; below the joint, by inner head of the gastrocnemius.

It is covered in by the skin, superficial fascia and fascia
lata.

Its floor is formed* by the lower part of the posterior sur-
face of the femur, the ligamentum posticum Winslowi and the
popliteus muscle and its fascia.

It contains: — ■

The popliteal artery and branches; popliteal vein receiving
the external saphenous vein (vein to the outer side) ; internal
and external popliteal nerves and branches; articular branch of
obturator nerve ; branch of small sciatic nerve ; four or six
lymphatic glands, and a quantity of adipose and areolar tissue.

ANATOMY OP HERNIA.

Hernia is the protrusion of any part of a viscus from its
natural cavity through the inclosing walls of the cavity. As
usually understood, it refers to the protrusion of the intestine
or mesentery, or both, from the abdominal cavity. The most
common forms are : —

External or oblique inguinal hernia;
Internal or direct inguinal hernia;
Femoral hernia;
Umbilical hernia.

1. Oblique inguinal hernia escapes from abdominal cav-
ity at the internal abdominal ring, carrying before it a pouch

si RGICAL ANATOMY

;'.»;

of peritoneum, descends along the inguinal canal in front of
the cord, and emerges at the external opening. The anatomical
parts concerned are the inguinal canal, with its interna] and
external abdominal rings, the transversals fascia (vide Fascia),
the peritoneum (vide Peritoneum) and Poupart's ligament.

Fig. 141.

Dissection of the inguinal canal: A, external oblique; B, li, in-
ternal oblique; 0, transversalis; D, conjoined tendon; E, rectus ab-
dominis with sheath opened; G, fascia transversalis; //, cremaster;
/, infundibular fascia.

The mguvnal or spermatic canal is about one and a half
inches in length, extending from the internal abdominal ring
to the externa] abdominal ring. It serves for the passage of
the spermatic cord in the male, and the round ligament with

essele in the female. Us boundaries are: —

398 HUMAN ANATOMY.

In front, skin, superficial fascia, the aponeurosis of the
external oblique muscle, the lower border of the internal oblique,
and a small portion of the cremaster muscle;

Behind, the fascia transversalis, the conjoined tendon of
the transversalis and internal oblique muscles, the transversalis
fascia, and subperitoneal fat and peritoneum;

Above, by the arched border of the internal oblique and
transversalis muscles; r~

Below, by the connection between Poupart's ligament and
the transversalis fascia.

The internal abdominal ring (annulus ingirinalis abdomi-
nalis) is an oval opening in the transversalis fascia about half
an inch above Poupart's ligament, midway between the sym-
physis pubis and the anterior superior spinous process of the
ilium. It is bounded — •

Above and externally by the arched fibers of the transver-
salis muscle ; below and internally by the deep epigastric vessels.

It transmits a funnel-shaped fascia from its margins, the
in fun dib uliform fas cia.

The external abdominal ring (annulus inguinalis subcu-
taneus) is a triangular opening between the two pillars in the
aponeurosis of the external oblique muscle, to the outer side and
just above the spine of the pubes. It is about half an inch
wide and one inch long, and is bounded —

Above, by the intercolumnar fascia; below, by the spine
and crest of the os pubis, and on either side by the pillars or
columns of the ring formed by the free margins of the aponeu-
rosis of the external oblique.

From the margins of the external abdominal ring arises
the intercolumnar fascia.

Poupart's ligament, or the femoral arch (ligamentum in-
guinale), is the rounded lower fibrous margin of the external
oblique muscle, extending between the anterior superior spine of
the ilium and the spine of the pubes. The portion of the
aponeurosis which is inserted into the pectineal line has received
the name of Gimbernat's ligament (ligamentum lacunare).

The triangular ligament or ligament of Colles (ligamen-
tum inguinal reflexum) is the reflected inner portions of Gim-
bernat's and Poupart's ligaments attached to the sheath of the
rectus.

The epigastric artery (a. epigastrica inferior) holds a very
important anatomical relation to the inguinal canal and inter-
nal abdominal ring. It ascends between the peritoneum and
transversalis fascia to reach the sheath of the rectus muscle

M RGICAL ANATOMY.

39U

Fig. 142.

Deep Femoral Region-the Femoral Vessels, etc., cut across as
they emerge under Pouparfs ligament. AC, anttrior crural nerve;
( 7 .dge of the conjoined tendon; CK, crural ring; K, dotted line in-
dicates the course of the deep epigastric artery; FB, femoral sheath;
Q Gimbernafa ligament; TP, llio-pectineal ligament; P, Pouparfs
ligament; 'PE, pectineus muscle. This muscle rests upon the pubic
bone and is covered by its fascia— the pectineal fascia— which is some-
what thickened Immediately beneath Pouparfs ligament, where it is
known as the pubic ligament of Cooper. It will be noticed that the
femoral sheath is divided into three compartments: the outer for the
femoral artery; the middle for the femoral vein; the inner (OR) is1
ti,. . rural ring, the mouth of the crural canal. (McQrath.)

400 HUMAN ANATOMY.

along the inner and lower margin of the internal ring and
beneath the spermatic cord.

The coverings of oblique inguinal hernia are : —

(1) Skin; (2) superficial fascia ; (3) intercolumnar fascia;
(4) cremaster muscle and fascia; (5) fascia transversalis, or
infundibuliform fascia; (6) subserous connective tissue; (7)
peritoneal sac.

- 2. Direct inguinal hernia escapes through the abdom-
inal wall, within Hesselbach's triangle, internal to the epigas-
tric artery, and through the external abdominal ring, pushing
before it a pouch of peritoneum.

Hesselbach's triangle is a space situated at the lower ante-
rior part of the abdominal wall on either side. It is bounded
as follows: —

Externally, epigastric artery;

Internally, the outer margin of the rectus abdominis
muscle ;

Below, Poupart's ligament, forming its base. The struc-
tures forming the abdominal wall at this cavity are, from with-
out inward: —

1. Skin;

2. Superficial fascia;

3. Intercolumnar fascia;

4. Conjoined tendon of the transversalis and internal ob-
lique ;

5. Fascia transversalis;

6. Subserous tissue;

7. Peritoneum.

The anatomical parts concerned in direct inguinal hernia
are the same as those in the indirect, already given. The cov-
erings of direct inguinal hernia are those just enumerated.

3. Femoral, hernia escapes through the femoral ring,
carrying before it a pouch of peritoneum, descends through the
femoral canal and emerges through the saphenous opening in
the fascia lata. The anatomical parts concerned in this hernia
are: —

The femoral ring, the femoral or crural canal, the septum
crurale, crural sheath, deep crural arch and the saphenous
opening.

The femoral, or crural ring (annuhis femomlis) , is an oval
opening, about an inch and a half in diameter, larger in the
female and situated below Pou'part's ligament, between the
inner side of the femoral vein and the margin of Gimbernat's
ligament. It is the abdominal opening of the femoral canal

SURGICAL ANATOMY. 401

(canalis femoralis), and it is closed in the recent state by the
septum crurale and a small lymphatic gland. It is bounded —

In front, by the deep femoral arch and Pouparf s ligament ;

Behind, by the pubes, covered by the pubic portion of the
fascia lata and the pectineus muscle ;

Externally, by the femoral vein, from which it is sep-
arated by a fibrous septum ;

Internally, by the deep femoral arch, Gimbernat's ligament,
the transversalis fascia and the conjoined tendon.

The femoral canal (canalis femoralis) is a space from a
quarter to half an inch in length, extending from Gimbernat's
ligament to the upper margin of the saphenous opening.
Bounded above by the femoral ring and below by the saphenous
opening. It is the innermost compartment of the femoral
sheath.

Anterior wall — transversalis fascia, separated by the falci-
form process (margo falciformis) of the fascia lata;

Posterior wall — iliac fascia and pubic portion of the fascia
lata;

External wall — fibrous septum of the femoral vein;

Internal wall — Gimbernat's ligament, deep crural arch and
the junction of the iliac and tranversalis fascia.

The septum crurale (septum femorale musculus) is a layer
of dense areolar tissue, supporting small lymphatic glands and
closing in the femoral ring. It is perforated by numerous lym-
phatic vessels, and forms a barrier to the escape of hernia at
this point.

The crural or femoral sheath (fascia cruris) is a prolonga-
tion downward of the fascia lining the abdomen (transversalis
fascia in front, iliac fascia behind the vessels), closely adhering
to the femoral vessels to about an inch below the saphenous
opening (fossa ovalis). Its upper part is funnel-shaped and
it- Lower part continuous with the sheath of the vessel. It is
divided by septa into three compartments; in the outer is lodged
the femoral artery; the middle is occupied by the femoral vein;
and the innermost, the femoral canal, is empty, or occupied by
a Lymphatic gland. Its outer border is pierced by the genito-
c rural nerve, its inner by the internal saphenous vein.

The deep femoral arch is a fibrous thickening of the trans-
versalis fascia which forms the anterior Avail of the femoral
gheath. It is* also known as the deep crural arch.

The saphenous apenmg is an oval aperture of half an inch
in width, an inch and a half in length in the upper and inner
part of the fascia lata, between its two divisions, the iliac and

26

402

HUMAN ANATOMY.

pubic portions. It is bounded externally by the falciform
process of Burns, internally by the pubic portion of the fascia
lata, which curves upward behind the saphenous vein. The
opening is covered externally by the cribriform fascia (fascia
cribrosa) and the skin.

| The coverings of femoral hernia are: — ,

1. Skin;

2. Superficial fascia;

3. Cribriform fascia ;

Hnttrhrlayrref

V,., r™j *"«■♦- ~»

Fig. 143.
Male perineum, superficial dissection. (Lydston.)

4. Femoral sheath, crural sheath, or fascia propria;

5. Septum crurale;

6. Subserous connective tissue;

7. Peritoneal sac.

ISCHIORECTAL REGION AND PERINEUM.

The outlet of the pelvis is a lozenge-shaped space divided
by an imaginary line drawn in front of the anus, transversely
between the anterior margin of the tuber ischii/into two parts,
the ischiorectal region behind and the perineum in front.

The ischiorectal region contains the external (m. sphincter
ani externus) and internal sphincters (m. sphincter ani inter*

SURGICAL ANATOMY.

403

mis), the corrugator cutis ani and the ischiorectal fossa (fossa
ischwrectalis) . The latter is a pyramidal cavity, its apex
reaching to the junction of the obturator and anal fascia and
its l>ase formed by the skin. It is bounded—.

Behind, by the edge of the great sacrosciatic ligament and
gluteus maximus muscle; internally, by the levator ani, covered
by the anal fascia, sphincter ani and coccygeus muscle; exter-
nally, by the tuber ischii and obturator fascia.

Artfrj of Cerpat Cavtnnmn
0*r*at Artorg j/* Pent*

Aritry f/ Buli.
Zmttmal PaJie Arte

C*rp*r* dam

FIG. 144.
Male perineum, deep dissection. (Lytlston.)

It t O/i hi ins;

The internal pudic artery, nerve and veins inclosed in the
fa-rial canal or canal of Alcock ;

The inferior hemorrhoidal vessels and nerves;
The perineal and fourth sacral nerves; and
A mass of areolar tissue.

PEEINEUM.

The perineum is the triangular space between the amis and
Bcrotum in the male, and between the aims and vulva in the
female. The skin is dark, thin, and supplied with sebaceous
and sudoriferous glands and is marked by middle Line or raphe.

404 HUMAN ANATOMY.

Fascia of the Perineum.

The pelvic fascia {fascia pelvis) at the brim of the pelvis
is continuous with the transverse and iliac fascia; covers sac-
rum, pyriformis muscle, external iliac artery and sacral nerves.
It forms the lateral true ligaments of the bladder {ligamenta
puboprostatica lateralia) in the male, and {ligamenta pubo-
vesicalia lateralia) in the female. It also forms the anterior true
ligament of the bladder {ligamentum puboprostaticum medium)
in the male {ligamentum pubovesicale medium,) in the female.
It forms arcus tendinege {arcus tendineus fascice pelvis), or
white line, corresponding to division of pelvic fascia into .two
layers, the obturator and rectovesical {fascia diaphragmatis pel-
vis superior), extending from pubis to spine of ischium, from
which originates the levator ani muscle, with rectovesical and
ischiorectal or anal fascia? above and below the muscle re-
spectively.

The obturator fascia {fascia obturatoria) , the continuation
of the pelvic fascia, incloses the pudic vessels and nerve in a
sheath, covers the internal obturator muscle and forms the pos-
terior layer of the triangular ligament.

Bectovesical or visceral layer of the pelvic fascia, the com
tinuation of the pelvic fascia, descends into the pelvis investing
the prostate glaud and the vesicoprostatic plexus of veins, the
bladder (forming the anterior and lateral true ligaments) and
the rectum. It is perforated in the female by the vagina.

Superficial perineal fascia {fascia superficialis perinei)
consists of superficial fat layer and deep membranous layer, the
fascia of Colles. The former is continuous with subcutaneous
layer of buttocks, thigh, and labia, and posterior to anus be-
come continuous with tissue of ischiorectal fossa. The superior
laijer passes from rami of pubis and ischium to the tuberosity
of ischia, covering ischiocavernous and bulbourethral muscles,
and becomes continuous with the deep perineal fascia.

The deep perineal fascia (triangular ligament of the per-
ineum— trigonum urogenitale or diaphragma urogenitale) is a
strong triangular membrane extending between the rami ischii
et pubis, its apex attached to the under surface of the sym-
physis. It is often described as consisting of two layers, the
superior, deep or posterior layer {fascia trigoni urogenitalis
superior), and inferior, anterior or superficial layer {fascia
trigoni urogenitalis inferior) . It is pierced by the membranous
urethra, and sends a fascia surrounding the urethral glands to
the spongy body. In the female it is weaker, the urethra also
pierces it, and it is continuous with the fascia of the vagina.

si i;<;i< Al. ANATOMY.

405

Muscles of the Perineum.

Ischiocaveknosl's (erector penis) arises in the inner sur-
face of the tuberosity of the ischium, and is inserted into the
side and under surface of the cms penis. In the female there
is a similar insertion into the clitoris. It serves to maintain
the organ erect. Nerve, perineal.

Erector clitoridis (m. ischiocarernosus) corresponds to
erector penis muscle in the male, but smaller.

Female perineum: .4, anus; IS, bulbo-vaginal; C, coccyx; G, glu-
teus maximus; P, perineal body; U, urethra; V, vagina; G, vulvo-
vaginal gland; 1, clitoris; 2, its suspensory ligament; 3, crura clito-
ridis; 4, erector clitoridis; 5, bulbo-cavernosus; 7, transversus perinaei;
8, sphincter ani; 9 and 10, levator ani; 11, coccygeus; 12, obturator
externus.

Accelerator ubism or ejaculatob beminis (m. bidbo-

cavernosus) arises from central tendon of perineum and from
mediaii raphe in front. It spreads out and is inserted from

behind forward to anterior surface of triangular ligament, bull)
and adjacent part of corpus spongiosum, to join fibers of
opposite side, and to sides of corpora cavernosa ; anterior to
erector penis and in fibrOUS expansion over dorsal Mood vessels

of penis.

It accelerates the How of urine and semen and contributes

to erection of the penis. Nerve, perineal.

406 HUMAN ANATOMY.

Vaginal constrictor or sphincter vagina (to. bulho-
cavemosus) , analogous to foregoing muscle, surrounds the orifice
of vagina. It arises from the centraL^endon and passes forward
on either side of vagina to be inserted into the corpora caver-
nosa and body of clitoris. It compresses the dorsal vein of the
clitoris.

Transversus perin^ei (superficialis) arises from inner
part of ramus of ischium, and is inserted into perineal center
in male, into the side of sphincter vaginae in the female. It
steadies the perineal center. Nerve, perineal.

Compressor urethrje (to. constrictor uretlirce) arises
from the rami of pubis and ischium, passes inward and with
its fellow of the other side, unites above and below the urethra,
surrounding it from the bulbous portion to the prostate gland
in the male. In the female it is inserted into the vaginal walls.

External sphincter ani (to. sphincter ani externus)
muscle arises from the apex of the coccyx and the superficial
fascia, and is inserted into the perineal center, blending with
the levator ani, accelerator urinae and transversus perinaei. It
closes the anus. Nerve, fourth sacral.

Internal sphincter ani (to. sphincter ani internus) is
an aggregation of circular fibers of the intestine, forming a
muscular ring one inch in breadth, surrounding the lower por-
tion of the rectum.

The external sphincter ani, the two bulbocavernosi and the
two transversus perinsei unite one-half inch in front of the anus
in the median line in the so-called central tendon of the per-
ineum.

Anal elevator (levator ani) arises in front from body
and ramus of pubis and symphysis, posteriorly from spine of
ischium, and on either side from angle -of arcus tendinew (white
line). It is inserted by posterior fibers into coccyx, and ante-
rior fibers into the muscle of opposite side in a median raphe
extending from coccyx to anus ; middle fibers into rectum, join-
ing with sphincter; anterior to prostate, blending with external
sphincter and transverse fascia. In the female it is inserted
into the vagina instead of the prostate.

It helps with its fellow to form the floor of the pelvis, and
supports the vagina, rectum and pelvic viscera. Nerves, infe-
rior hemorrhoidal and fourth sacral.

Cocctgeus muscle (coccygei) , from the spine of the
ischium and lesser sacrosciatic ligament, and is inserted into
the margin of coccyx and side of lower two segments of sacrum.

SURGICAL ANATOMY. 407

It raises the coccyx and forms the posterior part of the pelvic
floor. Nerve, anterior division of the fourth and fifth sacral.
The muscles of the female perineum are : —

Superficial Set.

Sphincter vagina', or bulbocavernosus;

Erector clitoridis ;

Transversus perinaei superficial ;

Sphincter ani ;

Levator ani :

Coccygeus.

Deep Set.

Transversus perinaei (profundus) ;

( SonstrictoT vagina? ;

Compressor urethra1.

The structures beneath the deep layer of the superficial
fascia are : —

Erector penis muscle ;

Accelerator urinae muscle ;

Transversus perinaei muscle and arteries;

Superficial perineal vessels.

The structures between the two layers of the deep perineal
fascia are : —

( 'ompressor urethra? muscle;

Membranous urethra;

Subpubic ligament ;

Dorsal vein of penis;

Pudic vessels and nerves;

Venous plexus;

Cowper's glands and ducts;

Arteries and nerves of bulb.

ANATOMY OF LATERAL LITHOTOMY.

The incision is made through a triangular interval formed
by the transversus perinaei, accelerator urinae and erector penie
muscles, and divides the following structures in the order
named : —

Skin and superficial fascia :

Inferior hemorrhoidal vessels and nerves;

Accelerator urinae muscle ;

Superficial perineal vessels and nerve (sometimes);

408 HUMAN ANATOMY.

Transversus perinsei artery and muscle;
Deep perineal fascia;
Anterior part of levator ani;

Part of compressor urethras and accelerator urinse muscles;
Membranous and prostatic portions of urethra;
Left lobe of prostate gland.
The structures to be avoided are : —
In median line, rectum and bulb of corpus spongiosum ;
Externally, internal pudic artery;
Forward, artery of the bulb ;

Backward, posterior part of prostatic gland and neck of
the bladder.

DENTAL ANATOMY.

Embkyologically the oral cavity is formed by the first
visceral and the frontonasal process. The first arch distad
branches dichotomously. The superior arm is the maxillary
process, the inferior arm the mandibular process. The latter
joins with its fellow of the opposite side in the midline {sym-
physis nuutdibularis) to form the lower jaw. Between the right

Fig. 146.

Maxillary and mandibular process of first visceral arch and
frontonasal process, a, frontonasal process; b, superior arm (maxil-
lary process) of first arch; C, inferior arm (mandibular process) of
first arch; <l, primitive oral cavity.

and left maxillary processes is interpolated the frontonasal
process. This marks a place of weakness, pathologically indi-
cated by congenital clefi palate and harelip.

The bony framework of the adult oral cavity consists of
the hard palate above and the mandible (Fig. lfs) and hyoid
(Fig. 35) bones below. The bones entering into the formation
of the hard palate, from before backward, are: (1) two pre-
maxillaries (distinguishable only in very young specimens). (2)
two mamillaries, and (3) two palate bones. The hard palate
presents four sutures: (1) median, (2) premaxillary-maxillarj
(poorly marked in Hie adult), (3) maxillary-palatine, and ( I)
palatine-sphenoid. The foramina of the hard palate are: (1)
anterior palatine, at the point where the preinaxillarY-niaxillarv

(409)

410

HUMAN ANATOMY.

suture crosses the median, subdivided into four openings, (2)
two posterior palatine, and (3) twg. accessory. These last four
foramina transmit the posterior descending palatine nerves and
vessels.

The alveolar process for the implantation of the teeth is a
ridge of bone superimposed peripherally, in the upper jaw, upon
the premaxillary and maxillary bones. When fully functioning
it is not demarcated from these bones, but before the teeth come
and after they go it does not exist. Its body is spongy. Its cor-
tex is dense, and surrounding each tooth root-socket it is some-
what condensed (lamina dura, of some significance radiographic-
ally for the prognosis of pyorrhea alveolaris). In cross-section

Fig. 147.

Sutures of the hard palate, a, premaxillary bone;
maxillary bone; c, palatine bone.

it is somewhat U-shaped. It has two free surfaces, the internal
and external alveolar plates. Of these the external is much the
thinner, which fact is taken advantage of in extraction.

The mandible (Fig. 148) exhibits an alveolar process essen-
tially similar to that of the maxillary. In cross-section the
mandible is U-shaped. The cortex is dense, the interior cancel-
lated. Within its body runs the inferior dental nerve and blood-
vessels inclosed in a cribriform tube in close proximity to the
roots of the teeth. In most cases the mental canal points for-
ward into the body of the bone, and hence it is a recurrent canal.
There are two foramina in the niandible: (1) inferior dental,
situated in the midvertical axis of the ramus at the intersection
of a line continuous with the free edge of the alveolar process;
(2) mental, situated about in the midhorizontal line of the body
at the intersection of a vertical line dropped from the second

DENTAL ANATOMY.

411

premolar or between the first and second premolars. The men-
tal foramen marks one of the favorite lines of fracture of the
mandible.

Over this bony scaffolding the soft tissues of the mouth are
molded. The hard palate is covered by a mucoperiostenni. Its
pitted surface is due to many small mucous glands which it
shelters. The gums covering the alveolar processes are also of a
mucoperiosteal nature. Normally between the teeth is a little
cushion of gum-tissne. serving to keep out food debris. Around
each tooth the gum is attached at the neck (enamel-cementum

Four mandibles ranging from birth to eighteen months. A, at
birth: li. at three months; C, at six months; /), at eighteen months.
• ■Internal Anatomy of the Face," M. 11. Cryer, M.D., D.D.S.)

junction), but a little free edge exists leaving around each toot!)
;i gingival trough.

The Boft tissues over the anterior part of the hard palate
and the palatine side of the alveolar ridge is raised into a num-
ber of transverse ridges (rugae), and, in the midline, an ineisal
pad.

The SOfl palate i- ;i backward continuation of the soft tis-
sues covering the hard palate, inclosing in their substance
muscle fibers. The anterior pillars of the fauces arbitrarily
mark the posterior limit of the oral cavity. In their substance
run the palatoglossus muscles.

Laterally and anteriorly the cheeks and li|is form the walls

of the oral cavity. The -Jit between the external alveolar plate
and teeth on the one side, and the cheeks and lips on the other

is known a- the preoral cavity or vestibule. The frenum l<il>ii is

412

HUMAN ANATOMY.

a delicate fold of tissue in the midline between the gum of the
external alveolar plate and the upper lip. In artificial dentures
room has to, be provided for its free movement.

The body of the cheeks and lips is composed of the muscles
of expression (Fig. 149). Internally they are covered by
mucosa, externally by the skin.

fig. 149.

Muscles of expression. Muscles of the right side of the head
and neck. 1, frontalis: 2, superior auricular; 3, posterior auricular;
4, orbicularis palpebarum; 5, pyramidalis nasi; 6, compressor naris;
7, levator labii superioris, alaeque nasi; 8, levator labii superioris; 9,
zygomaticus major; 10, orbicularis oris; 11, depressor labii inferioris;
12, depressor anguli oris; 13, anterior belly of digestric; 14, mylo-
hyoid; 15, hyoglossus; 16, stylohyoid; 17, posterior belly of digastric;
18, masseter; 19, sternohyoid; 20, anterior belly of omohyoid; 21,
thyrohyoid; 22, 23, lower and middle constrictors of the pharynx;
24, sternomastoid ; 25, 26, splenius; 27, levator scapulae; 28, anterior
scalenus; 29, posterior belly of omohyoid; 30, middle and posterior
scalenus; 31, trapezius. ("Applied Anatomy and Oral Surgery,"
Robert H. Ivy.)

The anterior orifice of the oral cavity (rima oris) is a trans-
verse slit bounded by the projecting lips. The orbicularis oris
(page 132) has no separate existence. The sphincter action of
the lips is accomplished by a complicated interlacing of the
muscle fibers from buccinator, depressor labii inferioris, depres-
sor anguli oris, zygomaticus and risorius. The buccinator forms
the muscular body of the cheek. Its attachment to the maxilla
has to be considered in outlining upper artificial dentures.

DENTAL ANATOMY.

413

The masseter, temporal, external and internal pterygoids
all innervated by the fifth nerve, are the "muscles of mastica-
tion" (pages 132 and 133). Between the right and left halves
of the body of the mandible is the muscular floor of the mouth —
digastric, geniohyoid and mylohyoid (.page 134).

The floor of the oral cavity presents the tongue, with its
frenum; on each side of this an elevation indicating the posi-
tion of the sublingual glands, and anteriorly to the frenum, a
papilla for the orifices of the sublingual and submaxillary ducts.
For the description of the tongue see pages 135 and 388.

For the salivary glands see pages 229-230.

Tooth development. </, dental ledge or lamina; b, tooth germs of
deciduous teeth.

For the temporomandibular articulation see pages 105
and 106.

The cranial nerves of direct interest for the dentist are

fifth nerve, seventh nerve, ninth nerve and twelfth nerve. (See

pages 311-316 and Figs. 116 and 117). Especially fifth and

seventh nerves must be thoroughly mastered. (Chart facing

122.)

The external carotid artery (pages 180-185 and Figs. 79
and 81) is the most important artery for the dentist. See also
table on pages 200-204. For the venous system of special in-
terest to the dentist see pages 210-213.

The nasal cavity and its accessory sinuses not infrequently

have relations of dental interest (Figs. 125, 126 and ]~yt and

355 and 356). The relations of the roots of the upper

second premolar, first and second molars to the Hour of the

maxillary -inns (antrum of Highmore) is very intimate and

414

HUMAN ANATOMY.

important. The roots of the two last-named teeth always indent
the floor of this sinus.

The mandible is raised by the masseter, temporal, external
and internal pterygoids; depressed by the anterior belly of the
digastric and geniohyoid when the hyoid bone is fixed ; protruded
by external and internal pterygoids as well as slightly by the

Dental lamina

Epidermis

Tooth development. ("A Laboratory Manual and Textbook
of Embryology." Prentiss.)

superior portion of the masseter; retracted by the posterior
fibers of the temporal; and rotated by the fixation of one exter-
nal pterygoid with synchronous contraction of the other (the
internal pterygoid assists in rotation).

The teeth are inserted by a gomphosis joint in the alveolar
processes of the lower and upper jaws. In man tbere is a
deciduous and a permanent set. There are twenty deciduous
teeth; five in each quarter of the jaw apparatus: 2 incisors, 1
canine and 2 molars (Fig. 86, page 226).

DENTAL ANATOMY. 415

There are thirty-two permanent teeth; eight in each quar-
ter of the jaw apparatus: 2 incisors, 1 canine, 2 premolars 3

molars (Fig. 87, page 227).

The human tooth presents a crown and a root. The crown
is outside of the gum, and is covered with enamel. The root is
for the insertion of the tooth, and is covered with cementum At
the junction of the crown and root is a constriction, the neck or
cervix. The body of the tooth is formed of dentine. Within
the dentine is the pulp which in the crown is contained in a
relatively large chamber, sending out cornua roughly corre-
sponding to the cusps of the tooth; in the root the pulp is re-
stricted to the narrow canal terminating outwardly at the root
apex through one or several foramina.

In the seventh fetal week the oral epithelium thickens along
a line roughly corresponding to the future dental arch pro"
trading into the underlying jaw-mesenchvme. In each jaw at
ten points in this dental ledge, on its deep free edge, localized
thickenings become noticeable. These are the 'first signs of the
tooth-germs of the deciduous teeth. Each of these knobs be-
comes mvagmated, the cavity filled with vascular mesenchymal
tissue, the dental papilla. By progressive development the part
derived from the oral epithelium becomes the enamel-organ of
the future tooth. From the enamel-organ are formed enamel
and Nasmyth's membrane; from the dental papilla, dentine and
pulp. J he dental ledge connecting the tooth-germs with the
oral epithelium becomes fenestrated and eventually disappears.
_ Linguad and distad to each of the deciduous tooth-germs
arises, from the same dental ledge, the enamel-organ of the cor-
responding permanent tooth. The three permanent molars are
derived from a free prolongation of the dental band, extending
distad to the second deciduous molar.

Ei uption of Deciduous Teeth.

Mandibular firai incisors 0 to 8 months.

Maxillary first and second incisors .... 8 " 10
Mandibular second incisors )

-Maxillary and mandibular first molars/ 12 " 14

canines .... IS " 20 "

second molars. 28 " 32 "

416 HUMAN ANATOMY.

Eruption of Permanent Teeth.

Maxillary and mandibular first molars 6 years.

" " " " incisors 7 "

" " second incisors ....... 8 "

" " first premolars 9 "

" second premolars ... 10 "

" canines 11 "

" second molars 12 "

" " " third molars 17-25

HISTOGENESIS OF THE DENTAL TISSUES.

Enamel. — A delicate cuticular zone appears at the inner
end of the amelohlast. This*, with its fellows of adjoining cells,
becomes differentiated into rod-like segments (enamel-processes
or processes of Tomes) : these develop into the enamel prisms
and interprismatic substance. The enamel-processes gradually
become calcified by the deposition of granules and spherules,
first appearing in the axis of the prism and later extending to
its periphery. These spherules are, in chemical nature, calco-
globulin; and morphologically, are known as calcospherites.
The same ameloblasts suffice for the deposition of the entire
mass of enamel. This is formed from within outward, i.e., in
the reversed direction followed by the growth of dentin. It is
as yet undecided whether enamel is a secretion or a conversion
of the ameloblasts, but the balance of opinion would seem to be
in favor of the latter view.

Dentin. — In the formation of dentin the odontoblasts play
much the same role that is played by the osteoblasts in produc-
ing the matrix of bone. A thin homogeneous layer — membrana
prceformativa — overlying the odontoblasts is the earliest trace.
This, however, is only part of the general dentinal ground-sub-
stance— matrix — which for a time is without fibrous structure
and uncalcified.

Hopewell- Smith does not agree with the above description,
which is the one generally accepted. According to him the
classical "odontoblasts" have nothing to do with the formation
of dentin-matrix, which is formed by a calcification proceeding
from certain cells of the pulp. The walls and contents of the
tubuli are manufactured probably by the classical "odonto-
blasts."

Cementum. — This is a product of the osteoblasts (cemen-
toblasts) of the periodontal ( alveolo-dental ) ligament. The
process is almost identical with the development of subperiosteal
bone. Cementum is distinguished by the unusual number of

DENTAL ANATOMY.

417

transversely placed bundles of fibrillar — or Sharpey's fibers.
Many of these are imperfectly calcified. The cementum appears
first in the vicinity of the neck of the tooth and advances
towards the apex of the root as the radicular dentin is laved
down.

The knowledge of root-fonnation is important. The extent
of root-growth at various ages is graphically illustrated by
Fig. 152.

The dental tissues are: (1) Xasmytlvs membrane, (?)
enamel, (3) dentine, (4) cementum, (5) pulp. Nasmyth's
membrane is a pellicle 9 to 18u. thick) covering the enamel, long
persisting, of high organic content, resistant to the action of
acids. It is two-layered: (1) outer, of cornified remnants of
enamel-organ; (2) inner, structureless, consisting of the last

V*°«f.

2.SII week embryo

FKi. 152.
Root growth.

formed, imperfectly calcified portion of the enamel-prisms.
The enamel is the hardest tissue of the human body (containing
!»^ per cent, of inorganic salts). It consists of prisms (.'5.4-4.5^
in diaMeter) running approximately at right angles to the ex-
ternal surface of the tooth, in a slightly spiral course to the
dentine. Between these prisms is a cementing substance. In
the outer portions of the enamel, intercalated or accessory
prisms have been described. The margin of each enamel-rod is
straight and smooth, but may optically appear varicose, due to
the beaded nature of its more highly calcified central portion.
The brown stria- of Retzius are pigment zones running in the
general direction, of the contour of the tooth. The prism-
stripes of Schreger are alternate dark and light bands at right
;mgle- to the striae of Retzius in the enamel, cut in axial longi-
tudinal pection and examined hv reflected light.

The dentine contains about 72 per cent, of inorganic salts.
It- histologic character La principaly due to the dentinal tubuli

87

418 HUMAN ANATOMY.

(1.3-2/u- in diameter), which, running sinuously from the pulp
to the enamel, contain the dentinal fibers, the odontoblastic
processes. These tubuli branch and anastomose, some of them
ending in the enamel in the form of enamel-spindles. The
sheath of Newman is 'a delicate membranous wall of the den-
tinal tubule. The dentinal substance between the tubuli is
similar to the matrix of bone. Imperfections in the calcifica-
tion of the dentine are indicated by the interglobular spaces and
contour lines of Owen in the coronal portion, and the granular
layer of Tomes at the dentine-cementum junction in the root
portion. Schreger's lines in the dentine "are merely markings,
which, running parallel to the external edge of dentine, are pro-
duced by the coincidence of primary curvatures of the tubules."

The cementum is usually described as being composed of
relatively amorphous concentric lamellae with lacunae. There is,
however, good authority (Hopewell-Smith) for considering the
lacunae indicative of some pathological process. The cementum
increases in thickness from the gum-margin to the root-apex
and also" with age. The relation between the enamel and
cementum is variable ; inmost cases these two tissues just touch
each other-.

The pulp shows connective tissue of an embryonal type.
There are very few or no elastic fibers in it. Its nerve- and
blood-supply is abundant. Lymphatics are generally denied,
but recent work indicates their presence. The peripheral cells
are differentiated into a more or less stratified columnar ele-
ments, the odontoblasts, which send their processes into the
dentinal tubuli. The nerves accompany the blood-vessels and
from a peripheral plexus beneath the odontoblasts, sending
fibrillae between thes% cells. Any further extension of these
nerves, e.g., into dentine, has as yet not been proved.

The periodontal ligament is a collection of fibrous tissue
stretching from the dentine to the lamina dura of the alveolar
socket. The arrangement of the fibers is adjusted in general to
meet the strain of occlusion. This ligament is normally, in
youth, relatively thick in diameter, decreasing with age and
pathological conditions. It contains cell-nests or "rests," rem-
nants of the epithelial sheath of Hertwig, once described as
glands.

The deciduous teeth (Fig. 86, page 226) are smaller than,
and show a more marked cevical construction than, the per-
manent teeth. Also the roots of the milk-molars exhibit a more
marked flaring. The first and second deciduous incisors re-
semble in close detail the corresponding permanent teeth. The

DENTAL ANATOMY. 419

second milk-molar bears a greai resemblance to the first per-
manent molar. The occlusal surface of the maxillary (upper)
first deciduous molar is irregularly quadrangular in outline, and
presents three cusps ; two buccally and one lingriallv. It has three
roots. The occlusal surface of the mandibular (lower) first
deciduous molar is quadritubercular (two buccal and two lingual
cusps). It has two roots, one mesial, one distal.

The Permanent Teeth.

Maxillary first (central) incisor, chisel-shaped; labial sur-
face somewhat convex; lingual, concave; incisal edge curves over
into distal surface; incisal-mesial angle sharp; root conical.
Implanted in premaxillary bone ( Fig. ST, page 227).

Maxillary second (lateral) incisor closely resembles upper
first incisor. It is about two-thirds the size of this latter tooth.
Implanted in premaxillary bone.

Maxillary canine; convex labial surface presents a cutting
edge with a mesial and a distal slant; latter the longer; lingual
surface almost flat or slightly convex; near gingival border is a
small protuberance or cingulum; root longest in human mouth,
irregularly conical in shape, tapering from neck to apex.

Maxillary first premolar; bicuspid crown (one lingual, one
buccal cusp); latter the larger; buccal surface presents a free
mar-in with mesial and distal slant, former generally the
longer; root generally flattened and grooved on its mesial and
distal sides, or separated into a buccal and a lingual root
(Pig. 153).

Maxillary second premolar; closely /esembles above tooth;
slightly smaller; its crown is lower; distal slant on free margin
of its buccal surface slightly the longer; root slightly the longer,
rarely divided, much flattened mesiodistally.

Maxillary first molar; occlusal surface irregular rhombic in
outline with four cusps (two buccal, two lingual) ; mesiobuccal
cusp largest; distolingual cusp distinctly marked oil' from the
other cusps by a deep groove ; three roots (1) mesial or mesio-
buccal, (2) distal or distobuccal, (3) lingual; (3) largest,
conical in form, circular in cross-section; mesial root larger than
distal, oval in cross-section, with buccolingual axis the longer;
distal root also has the same eross-section (Fig. 154).

Maxillary second molar; smaller than above tooth; other-
wise greai similarity; distolingual cusp noticeably reduced;

three roots, closely resembling those of above tooth.

420

HUMAN ANATOMY.

Maxillary third molar; same structural form as the two
above teeth, but many variations; cusps more poorly marked;
distolingual cusp often absent; smallest tooth of the molar

Fig. 153.

Occlusal surfaces of teeth. ("Descriptive Anatomy of the Human
Teeth," G. V. Black, M.D., D.D.8., 8c. D.)

series ; roots may be the typical three, or these may be fused more
or less completely into one, or there may be supernumerary roots.
Mandibular (lower) first and second incisors; very similar
to maxillary second incisor, but more slender; incisal edge of
first incisor is almost at a ri°;ht ansrle to the lono- axis of the

DENTAL ANATOMY.

421

tooth: its mesio- and disto-incisal angles are sharp; second in-
cisor differs from the first by possessing an incisal t'ilge curving
at the distal angle and sharp at the mesial : roots, slender, Hat-
tended mesiodistally, oval in cross-section, with long- axis labio-
lingually.

Mandibular canine; markedly similar to maxillary canine,
slightly smaller, crown a little longer; root shorter, somewhat
flattened mesiodistally, nearly straight.

Mandibular first premolar: emallesi of the premolars; buc-
cal and lingual cusps, latter almost absent, neck much con-
stricted.

Pig. 154.

Cross sections through roots of teeth in *iln. Actual size. ("Descriptive
Anatomy of the Human Teeth," G. V. Black, M.D., D.D.8., 8c.D.)

.Mandibular second premolar; very similar to above tooth:
slightly longer; lingual cusp more marked; root, longer, larger,
generally straight.

Mandibular first molar; next to maxillary first molar the
largest; outline of occlusal surface trapezoidal; buccal margin
the longest; five-cueped (three buccally, two lingually) ; mesio-
buccal cusp largest : two root-, one mesial, one distal ; former the
larger, oval in cross-section, contains two root canals: distal
root, oval in cross-section, one root canal.

Mandibular second molar ; strikingly differed from the lirsi
in absence of distal (distobuccal) cusp: in all other respects
greai similarity.

Mandibular third inohir; two typical forms : (1) four-cus-

j"'d. similar to mandibular second molar (the more common

422 HUMAN ANATOMY.

form) ; (2) five-cusped, similar to mandibular first molar.
From these types great variation in size and form. On the
whole smaller than the two teeth immediately mesial to it;
typically two roots, relatively smaller than other molar roots,
single root also common; three roots not infrequent; however,
always three root-canals, two mesial and one distal.

The anatomy of the teeth, apart from their occlusal topog-
raphy, may be epitomized as follows : Incisors, canines and pre-
molars ; all one root with exception of maxillary first premolar,
which has two. Maxillary molars; three roots. Mandibular
molars; two roots. Incisors have a straight cutting edge;
canines and premolars have a mesial and a distal slant; mesial
slant the shorter, exce])t that the mesial slant of first maxillary
premolar is the longer. Mesiobuccal angle, acute. Eoots bend
distally; mesial root the longer.

Occlusion. — Maxillary teeth bite to the outside of the
mandibular teeth ; the buccal cusps of the mandibular premolars
and molars fit into the mesiodistal groove of the corresponding
maxillary teeth ; maxillary canine locks between mandibular
canine and first premolar. Every tooth in the human denture
opposes two teeth of the occluding set, except the mandibular
first incisor and maxillary third molar.

The point, or, better, the surface, of proximate contact is
that area on the mesial and distal surface of a tooth which ap-
poses a corresponding surface of the adjoining tooth. Eacli
tooth thereby receives mutual support from two adjoining teeth,
except the four third molars, which have only on their mesial
sides these surfaces of proximate contact.

Distribution

Termination & Function

CRANIAL NERVES.

Sommering

I. Olfaotory.

3. Motor ooull.

4. Pathetic?

(trochleares).

5. Trifacial (tri-
gemini).

6. Abducentet.

7. Facial.

8. Auditory.

9. Glosso-pharyn

10. Pneumogastrio
(vagus).

Superficial Origir

Opposite the internal
auditory meatus the
sensory root enters the

beneath and, later,
joins a branch of the
ganglion.

Pyramidal body and

r commis-
;rior white

f the opti

Optic thala
geniculate,
quadrigen

Aqueduct of Sylv
floor of fourth v

Sensory root, from 1
eral tract of the i
dulla oblongata.

Posterior part of

Gray nucleus in floor of
fourth ventricle.

Byfilnmentsfrom spinal Acressory portion from

\hout si iln/.i'ii filaments
from the space between
tiie pyramidal uud oli-
vary bodies.

Gray nucleus in floor
of fourth ventricle.

Sphenoidal between t'

Sphenoidal fissure.

Internal auditory

Internal auditory

in front of the pneu-
mogastric anil spinal
accessory.
Two gangliform en-
largements in jugular
foramen— jugular and
petrosal.

Jugular foramen in a
common sheath, with
tin- spinal accessory.

jugular

She. Ull

gastric.

t branch to the

[Nasal.

** Infra trochlear.
r ma.xillarv. three groups —

io-mnx. lossaj Splu,no_pa].ltil]C|
[ Posterior dental.

On the face 1 Nasal,
( Labial.
Inferior maxillary, two divii

Anterior, principally moti

Auric ulo- temporal 2

. Two auricular.

Communicating branches,
of distribution.

ranches before its exit are —

( Tympanic,

( i 'horda tympani.

Tempoi

c Temporal,

i-facial } Malar,

( Infraorbital.
( Buccal,
Ccrvi co-facial < Suprurnax diary,
( Inframaxillary.

Tympanic (Jacobson's

Muscular,

Tonsillar,

In jugular fossa— Auricular.

{Pharyngeal,
Superior laryngeal,
ReciiiTcnt laryngeal,
Cervical cardiac.

(Thoracic caTdiac,
Antenorpulua.nary.
Posterior pulmonary.
(Esophageal.
In abdomen — Gastric.

Accessory portion.

Spinal portion.

Distribution

Tuiht rrrniip — nasal septum.

Middle group — roof of nasal fossa.

Outer group — superior and middle tubinated bones.

Expands to form the inner layer of the retina o( the eye.

Superior — to the superior r
( 1st branch — to 1:

Inferior < 2d branch — to i:
( 8d branch— to t

r oblique or trochlcatis muscle.

Entera muscle c

Lachrymal gland, conjunctiva, in tinmen t of upper eyelid
I'orrugator supcrcillii, oceipiio-froninlis, nili-mm. nt of forehead
I'orrugator supcrcillii, orbicularis [.dpchrar'un, occlpuo-fromalis
Mucous membrane of no.-c. HI I egiliiiuii o| wings- and ti]. Of nose.
* 'tliary ganglion.
Ciliary iuusele and iris.
Integument of eyelids and
conji ' '

ncula lachrymalis, lachrymal e

"rUcularis palpebrarum, ■

Integument of temple and side of forehead.

Joins facial nerve.

Two branches to spheno-palatine ganglion.

Anterior branah to gums anil bucciintor muscle ; posterior branch to molar and second bicuspid

teeth, antrum, and gumg.
Incisor, canine, and first bicuspid teeth and inferior meatus
Orbicularis palpebrarum, con junem-ii and integument of lower
Muscles and integument of inner Bide of m
Labial glands, muscles, integument, and n
To the muscles of mastication the brinchei

, branches to parotid gland.

dealing with submaxillar! '.Miiglion ami hypoglossal ni'i
=i nn'iiibianc of tongue, mucous
2 with the hypoglossal n

emhraiie of mouth, gun

Molar and bicuspid teeth.

r belly of the digastric muscle.

. .Ties of tongue.
Retrateus uurmn. oecipito-fron!:dis (occipital portion).
Posterior belly of digastric, ril.iriso-m to glossopharyngeal r

n the submaxillary gland. Joins sub

i sympathetic or earolida.

Superficial branches to skin ami muscles of face, up branches levator muscles of mouth.

Buccinator and orbicularis oris muscles.

Platysma, muscles of chin and lip, depressors of angle of mouth.

Platysma. One branch joins tin.- superficial cervical nerve.

Cochlea.

Vestibule and semicircular canals.

Trunk of internal carotid artery, communicates with pncumogastiic and sympathetic.
Mucous membrane of pharynx.
Stylo-pharyngeus muscle.
Tonsil, soft palate, and fauces.

One branch to mucous membrane surface and base of tongue ; one branch to mucous
and papillre of sides of tongue.

ith auricular branch of facial. To integument of Pinna.
With a filament I'mm spinal ace. >sr,ry \,, pharyngeal plexus on middle constrictor.
Mucous membrane of interior of larynx and arytnioideus muscle. Exterior laryngeal i
'"' " yroid muscles, branch pharyngeal plexus.
■thyroid.

Two

ficial card:
To deep cardi

sple:

n left.

Anterior pulmonary plexUS.

Posterior pulmonary plexus.

Plexus gulfe. arouud the ccsophagus.

Stomach, communicating with solar, splenic, and hepatic plexuses.

eating branches to pharyngeal and superior laryngeal branches of the pneuuio-

id, trapezius, cervical plexus, occasionally great auricular nerve.

Omo-byoid (both bellies), sternodiyoid, sterno-thyroid.

Thyro hyoid muscle.

Styloglossus, hyoglossus, geuio-hyoid, genio hyogloesua.

With pm-uuiog's.-.trie, sympathetic, first and scpjji.l cervical and gll-talory I

Termination 0 Functio

Schneiderian muco

brane of the nosi

Nerve of special

foramen.
Nerve of special i

In the superior obliqui

(The trifacial is the large:

■gesk

In muscles. Nerve of i

Nerve of special

Nerve of motion.

Nerve of facial expression.

Internal ear.
Nerve of special si

muscle.
Nerve of special s(

In muscles, mucous r
brane, vessels, g
(thyroid).

Nerves of motion, si
tion, and sympathy.

In muscles.
Nerve of tni

INDEX.

Abdomen.

muscles of. 1-13

regions of, 2'M
Acervulus cerebri, 315
Acetabulum, 81
Alveoli of lower jaw, 36

of upper jaw. 31
Amphiarthrosis.
Anastomoses. 174
Anatomy, descriptive, 1

dental, 409

general. 1

of hernia. 396

of lateral lithotomy, 407

of teeth, 422

surgical, 391
Angle of jaw. :'.7
Anterior perforated space. 306
Annulus ovalis, 171

of subscapular fossa. 65
Antrum of Ilighmore. 29, 413

relation of roots of teeth to. 413
Anus, I'll
Aorta, 17s, 193
Appendicies epiploic*, 244
Appendix auriculae, 170, 172

ensiform, '^

vermiformis, 243
Aponeuroses. 129

pharyng. al, 230
Apophysis, 4
Aqueduct of Svlvius (iter e tertio,

etc.), 299
Aqueductus cochlea-, is

fallopii. is. ::us

vestibule, 18
Arachnoid, of brain. L"'7

of spinal cord, ::::!
Arbor vita-. 290, 285
Arch, deep palmar, 192

plantar, 202
Areola of mammae, 292
Arm, 63
Arnold's ganglion. 352

propria- renales, _•;*
Arterial anastomoses, 171
in, table of. 202
Arteries, belicine, 280

hepatic, 194, 249

lingual,

pharyngeal

sublingual, 180, isi
Arteries of the ankle-joint, 125

auditory canal. 36i, 376

auricle, 376

bom

choroid. 363

elbow |oint, 123

tcbian tube, .:7:i
::7I

hip-joint, 120

Arteries of the iris, 364
kidney, 268
knee-joint. 121
labyrinth, 382
larynx, 259
lung, it,::
mamma-, 292
mambrana tympani, 380
nasal fossa?, 356
nose, 355
oesophagus, 193
ovaries, 284
pancreas, 246
penis, 280
pharynx, 230
retina, 36S
shoulder-joint, 116
spleen, 251
stomach, 240
suprarenal capsules, 253
testicle, 278
thymus gland, 25L'
thyroid gland, 252
tympanum, 380
uterus. :!xi
wrist-joint, lis
Artery, anastomotica magna, 191, 200
aorta, 178, 193
arteria reeeptaculi, is:,
auricular, posterior, 183
axillary, 150
basilar, 188
brachial, 191
carotid, common. 17:i

external, 180

internal, 185
carotid (external I, 180
(internal I. 185
cerebral, anterior. 186

middle, anterior, 186

posterior, 186
choroid, anterior, 186
circumflex, anterior. 189, 191

posterior, 191
communicating, anterior, 186

posterior, 186
coronary, 178, 179
dental, inferior. L84
digital, 193, 202
dorsalis, hallucls, 201

pedis, 201
i -trie, deep, 198

superficial, 199
I. 181
lc, 194
femoral, L99
gluteal, 198

irrhoidal, inferior, 197

middle. 197
, 195

patlc, 194
iliac, circumflex, deep, 198

I 123)

424

INDEX.

Artery, iliac, common, 196

external, 106, 198

internal, 194, 196

superficial, 199
ilio-lumbar, 198
infraorbital, 185
innominate, 179
intercostal, 189
lingual, 180
lumbar, 195

mammary, internal, 189
maxillary, internal, 183
meningeal, anterior, 185

middle, 184

posterior, 188

small, 184
mesenteric, superior, 194

inferior, 195

obturator, 197

occipital, 181

ophthalmic, 185

palmar arches, 192

peroneal, 202
pharyngeal, ascending, 183
phrenic, 194
plantar, external, 202

internal, 202
popliteal, 200
profunda femoris, 199

inferior, 191

superior, 191
pudic, deep external, 199

superficial external, 199

internal, 197

pulmonary, 208
radial, 191
renal, 195, 268
sacral, lateral, 198

middle, 196
sciatic, 197
spermatic, 195
splenic, 194
subclavian, 187
subscapular, 190
suprarenal, 195
suprascapular, 189
temporal, 183
thoracic, acromial, 190

alar, 190

long, 189, 190

superior, 190
thyroid, inferior, 187

superior, 180
thyroidea ima, 252
tibial, anterior, 200

posterior, 201
transveralis colli, 189
tympanic, 184
ulnar, 192
uterine, 198
vaginal, 198
vertebral, 188
vesical, 196
Arthrodial joints, 105
Articulations, 104

acromioclavicular, 115
atloaxoid, 107
carpal, 119
carpometacarpal, 119
costosternal, 108
costotransverse, 108
costovertebral, 108
glenohumeral, 116
occipitoatloid, 107

Articulations, occipitoaxoid, 107

phalangeal, of foot, 127
of hand, 120

radioulnar, 117

sacrococcygeal, 111

sacroiliac, 110

sacroischiatic, 110

sacrovertebral, 110

sternoclavicular, 114

tarsal, 125

tarsometatarsal, 126

temporomaxillary, 105

tibiofibular, 123

vertebral, 106
Arytenoid cartilages, 254
Atlas, 58
Auricle, 376
Axilla, 395
Axis, 44, 58

cerebrospinal, 296

celiac, 194

optic, 358

thyroid, 188

visual, 358
Aaxis cylinder, 295
Azygos veins, 215

uvulaa, 136

Bartholin, duct of, 230

glands of, 292
Bauhin, valve of. 243
Bell, external nerve of, 336

internal nerve of, 336
Bladder, 270
Bodies, Malpighian, 268

Pacchionian, 297

geniculate, 311

restiform, 299
Body, ciliary, 363

olivary, 299

pituitary, 306

restiform, 299
Bone, astragalus, 93

calcaneum, 93

clavicle, 63

coccyx, 63

cuboid, 93

cuneiform, 78, 94

ethmoid, 24

femur, 86

fibula, 92

frontal, 8

humerus, 70

ilium, 82

incus, 380

hyoid, 38

innominate, 81

ischium, 84

lachrymal, 26

malar, 27

malleus, 380

maxillary, inferior, 35
superior, 29

nasal, 27

occipital, 12

os calcis, 93

os magnum, 78

palate, 32

parietal, 10

patella, 89

peroneal, 92

phalanges of foot, 96
of hand, 79

pisiform, 78

INDEX.

425

Bone, pubic, S5
radius. ~i
sacrum. 61_

scaphoid, 77, 94

scapula, 65

semilunar, 78

sessamoid, 98

sphenoid, 20

stapes. 3S0

sternum, 52

structure, microscopic, 5

temporal, 15

tibia, 90

trapezium, 78

trapezoid. 78

turbinated, inferior, 34
middle, 25
superior, 25

ulna, 72

unciform. 78

vomer. 35
Bones of the body, 3

of the carpus, 76

of the cranium. 8

of the face, 26

of the foot, 93

of the hand, 76

of hard palate, 409

of the lower extremity, 81

of the metacarpus, 76

of the metatarsus, 96

of oral cavity, 409

of the tarsus, 93

of the trunk. 52

of the upper extremity, 63

Wormian, 40
Bonnet, capsule of. 360
Bowman, capsule of, 268
Brain, commissures of, 308

development, 298

divisions of, 298

ventricles, 308

weights, average, 29S
Bronchi, 259

Brown stria of Retzius, 417
Brunner's gland, 242
Buccinator, 412

in artificial dentures, 412
Bulb of corpus cavernoflum, 280

of corpus spongiosum, 280
Bulbi vfstibuli, 291
Bulbs, olfactory, 323
Burns, process of, 402
Bursas of hip, 121

of knee, 122

Cecum, 243

f'alamus Bcriptorius, 313
Calices of kidney. 268
Canal, alimentary, 223

auditory external, 376
Internal, 18, 387

carotid, 18

central, of the cord, 332

crural. (00
I. 30
loral, i<m

for tensor tympani, 379

Hunter's, 199

hyaloid, 309

Infraorbital, 30

Inguinal,

DUtrii

of Huguier, :;78

Canal of Nuck, 237

of Petit, 369

of Schlemm, 364

of Stilling, 269

of the modiolus, 384

palatine, 31

pterygopalatine, 24

sacral, 61

spiral, of the cochlea, 384

Vidian, 24
Canaliculi, 374
Canalis reuniens, 385
Canals, membranous, 385

semicircular, 383
Canthus, 373
Capillaries, 175
Capsule, external, 310

internal, 310

of Bonnet, 360

of Glisson, 246

of Tenon, 360

of the lens, 369
Capsules, suprarenal, 252
Caput coli (cecum), 243

gallinaginis, 281
Carpus, 76
Cartilages of the larynx, 254

of Santorini, 255

of Wrisberg, 255

tarsal, 373
Cartilagotriticea, 255
Caruncula lachrymalis, 373

myrtiformes, 289
Cauda equina, 332
Cavity, cotyloid, 81

glenoid, of scapula, 68

orbital, 42

peritoneal, 235

preoral, 412

sigmoid, greater, 72
lesser, 74
of radius, 74
Cells, auditory, 387

ethmoid, 25

hepatic, 246

of Purkinje, 318

mastoid, 17, 378
Cement, 226
Cerebellum, 301, 318
Cerebrospinal system, 295
Cerebrum, 302, 320

convolutions of, 305

fissures of, 303

lobes of, 304
Cervix of penis, 279

of uterus, 293
Chorda; tendinse, 173
Choroid plexus, 310
Cilia, 373

Circle of Willis, 186
Circulus arteriosus iridis, 364

venosus, 292
Cisterna basolis, 297

magna, 297

pontis, 297
Claustrum, 310
Clavicle, 63
Cleft palate, 409
Clinoid processes, 21
Clitoris, 290

Clivus Blumenbacb.il, 21
Cloquct. canal of, 369
Coccyx, (;:;
Cochlea, membranous, 386

426

INDEX.

Cochlea, osseous, 383
Coeliac axis, 194
Collar-bone, 63
Colon, 243

flexures of, 243
Columnse carneas, 173

papillares, 173
Columns of spinal cord, 332
Commissures, cerebral, 308

anterior, 308

middle, 308

posterior, 308
Concha, 376
Condyles of femur, 88

of humerus, 71
Coni vasculosi, 274
Conjunctiva, 373
Conus arteriosus, 172

medullaris, 332
Convolutions of cerebrum, 305
Coracoid process, 68
Corium, 389
Cornea, 361

Cornicula laryngis, 255
Cornua of thyroid cartilage, 254

of ventricles, 308
Corona glandis, 279
Coronoid process, 37
Corpora albicantia, 306

cavernosa, 280

quadrigemina, 314

mammillaria, 306

striata, 310
Corpus Arantii, 172

callosum, 305

dentatum of cerebellum, 316

fimbriatum, 311

Highborianum, 274

luteum, 286

spongiosum, 280

striatum, 310
Corpuscles, Malpighian, 251, 268

of the blood, 175

tactile, 296
Corti, organ of, 387
Cortical substance of kidney, 267
Cotyloid cavity, 81
Coverings of the testicle, 273
Cowper's glands, 282
Crest, lachrymal, 26

nasal, 31

of the ilium, 82

of the pubes, 85

of the tibia, 90

turbinated, 31
Cribriform tube, 410
Cricoid cartilage, 254
Crista galli, 24

terminalis, 170
Crown, 415
Crura, anterior, 311

cerebri, 306

of clitoris, 290

of -penis, 280

posterior, 311
Crusta petrosa, 226 *

pontis, 316
Crypts of Lieberkiihn, 242
Cuneiform cartilages, 255
Cuneus, 305
Cupola of cochlea, 386
Cuticle, 389

Dartos, 273

Declivity, 21

Deciduous teeth, 414, 415, 418

Dental anatomy, 409

papilla, 415

ledge, 415
Dentine, 226, 415 -
Derma, 389

Descemet, membrane, 362
Diaphragm, 146
Diaphragma, sella, 296
Diaphysis, 3
Diarthrosis, 105
Digestion, organs of, 223
Discus proligerus, 286
Disk, optic, 367
Dorsum of scapula, 49, 65

sella?, 21
Douglas cul-de-sac, 237, 284
Duct, cystic, 250

hepatic, 250

lymphatic, 219

nasal, 375
Duct of Bartholin, 230

of Miiller, 276, 288

of Rivini, 230

of Steno, 229

of Wharton, 229

of Wirsung, 246

pancreatic, 246

thoracic, 219
Ducts, biliary, 250

ejaculatory, 278
Ductus cochlcaris, 373

communis choledochus, 250
Duodenum, 240
Dura mater of cerebrum, 296

of spinal cord, 332

Ear, 375

internal, 382
Earstones, 386
Embryology of oral cavity, 409

of teeth, 415

of lower jaw, 409
Emineintia articularis, 15

collaterals (pes accessorius), 312
Enamel, 226, 416
Enarthrosis, 105
Encephalon, 298
Endocardium, 173
Endolymph, 356
Endosteum, 5
Epidermis, 389
Epididymis, 273, 274
Epigastric region, 234
Epiglottis, 254
Epiphysis, 3, 4

Epethelial sheath of Hertwig, 41S
Equator of eyeball, 358
Eruption of deciduous teeth, 415

of permanent teeth, 4,16
Eustachian tube, 379
Eye, 356

appendages of, 372
Eyebrows, 372
Eyelashes, 372
Eyelids, 373

Fallopian tubes, 287
Fallopius, aqueduct of, 18

hiatus of, 18
Falx cerebelli, 296

cerebri, 296

[NDEX.

i-j;

Fascia, abdominal, 166

cremasteric, 274

cribiform, 168

denta, 312

iliac, 107

intercolumnar, 274

lata. 168

lumbar. 166

obturator, 404

of Colles, 4u4

of the head and face,

of the lower extremity, 168

of the neck. 166

of the trunk, 166

of the upper extremity, 167

palmar. 107

pelvic, 167

perineal, 404

plantar, 169

rectovesical, 4o(
Fascia-. 165
Fauces, 228
Femus, 86
Fenestra ovalis, 378

rotunda. 378
Ferrein, pyramids of, 268
Fibrocartilage, 104, 106, 124, 2.".4
Fibula, 92
Fillet, decussation of, 320

mesial. 320

lateral, 320
Fimbriae, 288

Fimbriated extremity. 288
Fissure, auricular, 19

calcarine, 304

callosomarginal, 304

collateral, 304

dentate, 304

Glaserian, 16

of Rolando, 304

of Sylvius. 304, 306

palpebral. 375

paracentral, 304

parieto-occipital, 304

pterygomaxillary, 41

sphenomaxillary, 40

sphenoidal. 23. 43

transverse, 30)
Fissures of cerebellum, 301

of cerebrum, 303

of liver, 247

of spinal cord, 332
Floor of the mouth, 413
Fetal circulation, 176

Folds, palpi bra I. 375

Fontanelles, 59

Foot

Foramen for Arnold's nerve, 19

cecum, 9

condyloid, 13, 18

ethmoidal, 24, 16

for Jacobson'8 nerve, 19

infraorbital, 24, 16

int'i rior dental, 410

int.ervi rti

lacerum anterius, 24, n

magnum, 13, ">o

mastoid. 16

mi dium, 16

III. lit;, I. 36, 110

malar. II

nutrient, .",

obtui

of Monro, 312

Foramen of Scarpa, 31
of Stenson, 31
of Winslow. 235
olfactory, 46

orbital. 24

ovale, 23

palatine, 31

posterius, 13

pterygopalatine, 22

rotundum, 23

sacral, 62

sphenopalatine, 32

spinal. 57

spinosum, 23

stylomastoid, 10

supraorbital, 8, 46

suprascapular, 67

thyroid, 81

Vesalii, 23
Foramina at the base of the skull 46

cf hard palate, 409

of mandible, 410

Thebisii, 171
Fort arm, 72, 14'.!
Fcrmatio reticularis, 316
Fornix, 31]
Fossa, canine, 20

caronoid, 71

digastric, 17

digital, 88

glenoid, 16, 68

hyaloid, 369

incisive, 20

infraspinous, 66

ischorectal, 402

jugular, 18

lachrymal, 0

navicularis of penis, 281

of vulvo, 289

olecranon, 71

ovalis, 171

pituitary, 21

pterygoid, 24

scaphoid, 24

sphenomaxillary, 44

sublingual, 36

submaxillary, 36

subscapular, 66

supraspinous, 66

temporal, 40

zygomatic, 40
Fossae, nasal, 45

of the skull, 40
Fourchette, 290
Fovea centralis. 367

hemispheric;!. 383

semielliptica. 383
Fr< nuluni, 31 1
Freiium lobii, II 1

in relation to artificial dentures,
412

preputii, 280

Call-bladder, 250
Call-duct, 250
Ganglia, 295

basic, 311

cervical, 3.",2

crania I I iO

lumbar. :::>'■'.

of fifth nerve

of the sympathetic, 350

sacra I

thoracic.

428

INDEX.

Ganglion, Arnold's, 352

Gasserian, 350

irnpar, 350

Meckel's, 350

of Ribes, 350

ophthalmic, 350

otic, 352

sphenopalatine, 350

spirale, 385

submaxillary, 352
Gasser, ganglion of, 350
Geniculate bodies, 311
Ginglymus, 105
Gingival trough, 411
Gladiolus, 52
Gland, lachrymal, 374

mammary, 292

parotid, 229

pineal, 315

prostate, 282

sublingual, 230

submaxillary, 229

thymoid, 252

thymus, 252
Glandula coccygea, 253
Glandula intercarotica, 253
Glands, Brunner's, 242

Cowper's, 282

ductless, 250

gastric, 239

intestinal, 242

lachrymal, 373

lymphatic, 219

Meibomian, 373

of Bartholine, 292

of Tyson, 279, 292

peptic, 240

salivary, 229

sebaceous, 390

solitary, 242

sweat, 390
Glans clitoridis, 290

penis, 278
Glenoid, 16, 68
Glisson's capsule, 246
Glottis, 255
Gomphosis, 105, 414
Graafian vesicle, 286
Groove, bicipital, 70

carotid, 21

cavernous, 21

infraorbital, 31

musculospiral, 70

mylohyoid, 36

nasopalatine, 35

optic, 21
Gubernaculum testis, 274
Gums, 224, 411
Gyri of brain, 305

Hairs, 390
Hamstrings, 160
Hamular process, 26
Hand, 76
Hare-lip, 409
Hard palate, 409

sutures of, 409

foramina of, 409

bones of, 409
Haversian canals, 6

system, 6
Head of the femur, 86

of the humerus, 70

of the ulna, 72

Heart, 170
Helicotrema, 385
Helix, 376

Henle, tubes of, 268
Hernia, anatomy of, 396

femoral, 400

inguinal, 396
Hiatus Fallopii, 18
Hirlus of kidney, 266
Hippocampus major, 312; minor, 312
His, bundle of, 171
Histogenesis of dental tissues, 416

of enamel, 416

of dentin, 416

of cement, 416
Hasner, valve of, 375
Houston, valves of, 245
Huguier. canal of, 16
Humerus, 70
Humor, aqueous, 368

vitreous, 368
Humors of the eyeball, 368
Hunter's canal, 199
Hydatids of Morgagni, 276, 288
Hymen, 288
Hypochondrium, 234
Hypogastrium, 234

Ileum, 241

Ilium, 82

Incisura intertragica, 376

Incisal pad, 411

Infundibulum of brain, 306

Inguinal regions, 234

Intestine, large, 242

small, 240
Internal capsule, 310
Iris, 363
Ischium, 84

Iter chordae anterius, 378
posterius, 378

e tertio ad quartum ventriculum
313
Ivory, 226

Jacob's membrane, 368
Jacobson's nerve, 3,16, 336, 365
Jejunum, 241
Joint, ankle-, 124

elbow-, 116

hip-, 120

rotators of the, 159

knee-, 121

shoulder-, 114

wrist-, 118
Joints, motions in, 105

structures of, 104

Kidneys, 266

Labia majora, 290

minora, 290
Labium tympanicum, 386

vestibulare, 386
Labyrinth, membranous, 385

osseous, 383
Lacteals, 219
Lacuna magna, 282
Lacunae, 6

Lacus lachrymalis, 373
Lamellae, 6
Lamina cinerea, 306

cribrosa (of sclerotic), 361
(of temporal bone), 18

IXDEX.

429

Lamina fusca, 361
reticularis. 387
spiralis, 3S4
Lamina of cornea, 361
Lanoisi, nerves of, 308
Larynx, 254
Layer, dermoid, 389
ganglionic, 367
molecular. 367
Leg, 90

Lens, crystalline, 36S
Lieberkiihn, crypts or follicles of.
Ligament, annular, of foot. 16S
of hand, 167
rhondroxiphoid. 109
conoid, 115
coronary, 121
cotyloid. 121

crucial, of knee-joint, 122
deltoid, 124
falciform, 401
Giiubernat's. 143, 398 400
glenoid, 116
iliofemoral or Y, 121
of Burns. 402
of Colles, 398
of Hey, 381
of Zina, 353,' 369
orbicular, 118

Poupart's. 143, 146. 398, 400
periodontal, 418
rhomboid, 114
round, of the liver, 249

of the uterus, 285
sacrosciatic, 110
stellate, 108
stylomaxillarv, 106
suspensory, of lens, 360
of liver, 249
of penis, 280
of spleen, 250

transverse, of hip-joint 121
trapezoid. 115

triangular, of perineum 104
Ligaments of the bladder, 271
broad, of uterus, 285
cheek, 107

of the knee-joint. 121
of the larynx, 255
of the liver, 248
of the ossicles, 381
of the ovaries, 285
of the sternum, 109
of the uterus, 284
peritoneal, 236-237
tarsal, 373
Ligamentum latum pulmonis 264
mucosum, 128
nuchas, 106
patella?, 121
pectlnatum iridis, 363
Buspensorium, 108
teres, 121
Winslowii, 121
Limbua lamina spiralis 385
Line, intertrochanteric, 88
Linea-aspera, 86
lliopectlnea, 81
quadrat!
Llngula, i'i
Liquor Uorgagni, 869
Lithotomy, structures affected 107
Liver 1M7

ligaments, 249

Liver, lobes of, 248

structure of, 246

vessels of, 249
Lobes of the cerebellum, 301

of the cerebrum. 302

of the liver, 248
Lobule of the ear, 375
Lobules of the liver, 246

of the lung, 262
Lobulus caudatus. 246

quadratus, 246

Spigelii, 246
Lower, tubercle of. 171
Lumbar regions. 234
Lung, broad ligament of 264
Lungs, 261
Lymphatics. 219

hepatic, 222, 249

of lung, 263

of penis, 281

of trachea and bronchi, 260

of uterus, 284
Lymph spaces of eyeball 360
Lyra, 311

Macula acoustica, 385
c.ribrosa, 383
lutea, 367
Malleolus, 92
Malpighi, bodies of, 251

pyramids of, 267
Malpighian corpuscles, 251. 268

tuft, 268
Mamma?, 292
Mandible, 410
Mandibular, canine, 421
fifth cuspid, 422
first incisor, 420
first molar, 421
first premolar, 421
fourth cuspid, 421
second incisor, 420
second molar. 421
second premolar, 421
third molar, 421
Manubrium of the malleus, 380

of the sternum. 52
Marrow of bone, 5
Masses, lateral, of ethmoid, 24
Mastoid process, 16
Maxillary, canine, 419
first, 419
first molar, 419
first premolar, 419
second, 419
second molar, 419
second premolar, 419
third molar, 420
Meatus auditorius externus 18
interims, 18, ::s;
nasi. 1:,

urinarius, 281, 291
Meckel's ganglion, 350
•Mediastinum, 264

testis, 274
Medullar, 5

oblongata, 299. 315
Medullary sheath, 294

substance, 266

Membrana basillaria 3S6
' anuloi a, 286
prseformativa, 416
puplllariB, 364
Ruyschlana

430

INDEX.

Menibrana tectoria, 387

tyrnpani, 380

secundaria, 362
Membrane, hyaloid, 369

interosseous, 119, 120, 124

Jacob's, 367

limiting, 367

of Descemet, 364

Nasrnyth's, 415, 417

of Reissner, 387

Schneiderian, 356

Shrapnell's, 378

vitelline, 286
Membranes of brain, 296

of the spinal cord, 332

synovial, 104

tarsal synovial, 126

wrist synovial, 120
Meridians of eyeball, 359
Mesencephalon, 314
Mesenteries, 236
Metacarpus, 80
Metatarsus, 96
Midbrain, 318
Modiolus, 384
Monro, foramen of, 312
Mons veneris, 290
Montgomery, glands of, 292
Morgagni, hydatids of, 276, 288

liquor, 369
Mouth, 223

Muller, duct of, 276, 288
Muscle, ciliary, 364

cremaster, 274

dilator pupillse, 364

levator glandulse thyroidea?,

of the auricle, 376

sphincter pupillas, 365
Muscles of the abdomen, 143

of Hilton, 258

of Houston, 405

of the arm, 148

of the back, 138

of the ear (external), 129

of the epiglottis, 258

of expression, 412

of the Eustachian tube, 379

of the eyeball, 369

of the face, 130

of the forearm, 149

of the foot, 163

of the hand, 153

of the head, 129

of the hip, 155

of the larynx, 257

of the leg, 160

of mandible, 414

of mastication, 413

of the neck, 133

of the palate, 135

of the perineum, 407

of the pharynx, 135

of the shoulder, 147 *

of the stomach, 239

of the thigh, 156

of the thorax, 145

of the tongue, 135

of the tympanum, 382
Muscular fiber, 128

floor of mouth, 413
Musculi pectinati, 172

Naboth ovules of, 284
Nasmyth's membrane, 415, 417

Nails, 390

Nares, 45

Nates of cerebrum, 314

Neck of femur, 88

of humerus, 70

muscles of, 133

triangles of, 391
Nerve, abducens, 326

Arnold's, 330

auditory, 328

Bell's external respiratory, 336
internal respiratory, 334

cells, 295

chorda tympani, 328

circumflex, 336

cochlear, 328

crural, anterior, 340

facial, 326

fibers, 295

genitocrural, 339

glossopharyngeal, 330

gluteal, superior, 340

hypoglossal, 331

iliohypogastric, 339

ilioinguinal, 339

intercostal, 339

intercostohumeral, 340

internal cutaneous, 337

interosseous, 337, 338

Jacobson's, 330, 382

laryngeal, 259, 330

maxillary inferior, 326
superior, 325

median, 337

motor oculi, 324

musculocutaneous, 337

musculospiral, 338

nonus or ninth pair, 330

obturator, 340

of Wrisburg, 337

olfactory, 323

ophthalmic division of fifth, 325

optic, 323

par vagum, 330

patheticus, 325

petrosal, external, 351
large deep, 351
large superficial, 351
small, 351

popliteal, 341

phrenic, 334

pneumogastric, 330

pterygopalatine, 351

pudic, 341

radial, 338

sciatic, great, 341
small, 341

spinal accessory, 331

subscapular, 336

suprascapular, 336

sympathetic, 350

tibial, anterior, 342
posterior, 341

thoracic, 336

trigeminus, 325

trochlear, 325

tympanic, 328

ulnar, 337

vestibular, 328

Vidian, 351
Nerve-fibers, optic, 323

tissue, 295
Nerves, 295

cranial, 323

INDEX.

431

Nerves, hepatic, 354
of ankle-joint, 125
of auditory canal, 377
of auricle. 370
of bladder. 273
of choroid, 363
of elbow-joint. 117
of Eustachian tube, 380
of eye, 372
of eyelids. 372

of eye-muscles, 363. 370, 371
of hip-joint. 121
of iris. 364
of Jacobson. 330
of kidney. 270
of knee-joint. 123
of Lancisi. 308
of larynx, 259, 330
of lung, 263

of membrana tymnani, 380
of nasal fossie, 356
of nose, 356
of pulp, 418
of ovaries, 287
of pancreas, 246
of pharynx, 230
of shoulder-joint, 115, 117
of spleen, 251
of stomach, 240
of suprarenal capsules, 253
of taste, 389
of testicles. 278
of thymus gland. 252
of tongue, 389

of trachea and bronchi, 260
of tympanum, 378
of uterus. _'M
of wrist-joint, 119
petrosal. 351
popliteal. 341
sciatic. :;n
spinal. 332
splanchnics, 353
table of, 343
thyroid, 252
Nervous system, 294
Newman, sheath of, 418
N« unlemma, 294
Neuroglia. 295
Neuroi
Nipple. 292
Nose, 355

Notch, cotyloid. 81
Interclavicular, 41
intercondyloid, 71

popliteal. 60

Kivinus. 378

tic, 84, 85
old, 37
supraorbital, 8
suprascapular, 67
Nuck, canal of. 237
Nucleus, red, 318
Nymphs,

<i cross, is
protuberance (i sternal) 12

' malt, 1 1

Occulsion, 122
Odont U6

L'31

Omentum, 235

Opening saphenous, 168, 401
Optic thalami, 311
Ora serrata, 365
Orbital cavities, 40
Organ of Corti, 387

of hearing. 375

of Rosenmiiller, 287

of sight.

of smell, 355
Organs of generation, female 283
male, 273

of taste, 3S9

of voice and respiration, 254

urinary, 266
Os ealcis, 93

orbiculare. 383

planum (orbital of ethnoid) 24

tinea?, 284

uteri, 284
Ossa innominata, 81

triquetra, 40
Ossification, 7

table of, 99
Ossicles of tympanum, 380
Osteology, 3
Otoliths, 386
Ovaries, 285
Oviducts, 286
Ovisacs, 286
Ovules of Xaboth, 284
Ovum, 286

Pacchionian bodies, 297
Palate, 228
Palpebrae, 373

Pampinaform plexus 277 287
Pancreas, 245
lesser. ■.'45
Papilla lachrymal, 374
Papilla? of skin, 389
Parovarium, 287
Pars cillaris retina?, 367

intermedia, of vulva 290
Peduncles of cerebellum. 302

of corpus callosum, 305 306
Pelvic girdle, 81
Pelvis, 112

of the kidney, 267
Penis, 278
Perforated space, anterior, 306

posterior. 306
Pericardium. 170
Perilymph, 385
Perineum, 403
female, 107

centn,] tendon of, 406
Periosteum. 5
P< ridontal ligament, 418
Peritoneum, 235
Permanenl teeth, 115, 416 11s
I'< ronei muscles, 163
Pes accessorius. 312
hippocampi, 312
Petit, canal of, 369
Pey< r's patchi s, 242
Phalanges of ear 370
of foot, 96
Of hand. SO
-. 230

I'ia mater oi brain, 297

Of Spinal cord, 331
Of tfie testes. 274

Pinna, or auricle, 376
Pituitary body, 253, 306

432

INDEX.

Plane, equatorial, 358

meridional, 358
Plantar arch, 169
Plate, cribriform, 24

perpendicular, 24

pterygoid, 24
Pleurae, 264
Plexus, brachial, 336

cardiac, 353

carotid, 352

cavernous, 352

cervical, 334

choroid, 310

of fourth ventricle, 310

hypogastric, 354

lumbar, 339

pampiniform, 277, 287

pelvic, 354

sacral, 340

solar, 354

splenic, 354

tympanic, 380
Plexuses of the sympathetic, 353
Plica semilunaris, 373
Point, nodal, 358
Poles of the eyeball, 358
Pomum Adami, 254
Pons Varolii, 300, 316
Portal system, 193, 215, 249
Porus opticus, 361
Pouches of membrana tympani, 378
Poupart's ligament, 143, 398, 400
Prism stripes of Schreger, 417
Preoral cavity, 412
Prepuce of clitoris, 291

of penis, 279
Process, acromion, 68

alveolar, 31, 36, 410

angular, 8

articular, 104

auditory, 20

basilar, 14

clinoid, 21

condyloid, 37, 72

coracoid, 68

coronoid, 37, 72

enamel, 416

ethmoidal, 34

falciform, 401

hamular, of cochlea, 384

Ingrassias, 23

jugular, 13

lachrymal, 34

malar, 31

mastoid, 17

maxillary, 28, 33, 34

mental, 35

nasal, 31

odontoid, 59

of pterygoid plate of sphenoid, 23

olecranon, 71

olivary, 21

orbital, 28, 33

of Tomes, 416

palate, 30

pterygoid, 23, 33

sphenoidal, 33

spinous, 4, 23, 56

styloid, 19

transverse, 57

unciform, 25

vaginal, 19, 22

vermiform, 243

zygomatic, 16, 28

Processes, ciliary, 364

clinoid, 21

of Ingrassias, 23
Processus, cochleariformis, 20

a cerebello ad medullam (inferior
peduncles), 302
ad potem (middle peduncles),

302
ad testes, 302, 315

gracilis, 380
Prominentia canalis facialis, 379
Promontory of sacrum, 61

of tympanum, 378
Prostate gland, 282
Prostatic sinus, 281

urethra, 281
Pterygoid processes, 23, 33
Pubes, 85

Punctum, lachrymale, 373 «

Pulp, 415, 418

arteries, nerves, lymphatics of, 418
Pupil, 363
Pylorus, 238
Ppramid, anterior, 299

posterior, 299

of tympanum, 378
Pyramids of Perrein, 268

of Malpighi, 267

of Wistar, 22

Radius, 74

Rami of inferior maxillary, 36

Ramus of ischium, 85

of the pubes, 85
Receptaculum chyli, 220
Rectum, 244

Regions of abdomen, 234
Reil, island of, 304
Reissner, membrane of, 387
Renal vessels, 268
Retina, 365

Ribes, ganglion of, 350
Ribs, 52
Ridge, mylohyoid, 36

pterygoid, 23

superciliary, 8
Rima glottidis, 257

oris, 412
Ring, abdominal, 398

crural, 400

femoral, 400
Rivinus, duct of, 230
Rugae, 411
Rods and cones (Jacob's), 367

of Corti, 381
Rolando, Assure of, 304
Rosenmiiller, organ of, 287
Rostrum of the sphenoid, 22

Sac, lachrymal, 375

Saccule, 385

Sacculus, laryngis, 257

Sacrum, 61

Sacs of the peritoneum, 235

Santorini, cartilages of (corniculo

laryngis), 255
Scala media, 386

tympani, 385

vestibuli, 385
Scapula, 65

Scarpa, foramen of, 31
Schindelysis, 105
Schlemm, canal of, 364
Schwann, substance of, 294

INDEX.

433

Sclerotic, 361
Scrotum. 273
Scute, 379
Sella turcica, 21
Septum, crurale, 401

lucidum, 310

nasi, 45

pectiniforme, 280
Sheath, crural, 401
Sehreger. prism stripes of, 417
Sharpey's fibers. 417
Sheath of Newman, 418
Shin, 90
Shoulder-joint, 116

blade, 65

girdle, 63
Sight, organs of, 356

Sigmoid flexure. 244
Sinus aortici or sinus of Valsalva, 173

circularis iridis, 364

of kidney, 267

of Morgagni (sacculus laryngis),
257

pocularis, 281
Sinuses, frontal, 10

of the dura mater, 210

of Valsalva. 173

sphenoidal, 22
Skin, 389

Smell, organ of, 355
Space, anterior perforated, 306

popliteal, 396

posterior perforated, 306

of Retzius. 271

subarachnoid, 297

subdural, 297
Spermatic cord, 276
Sphincter vesicae, 271
Spinal cord, 332

nerves, table of, 343
Spine, ethmoidal, 21

nasal anterior, 27

of the ischium, 84

of the pubes, 85

of the scapula, 66

of the sphenoid, 23

of the tibia, 90

pharyngeal, 14

posterior, 32
Spines of the ilium, 84
Spinous processts, 4, 23, 56
Spleen, 250

Splenic flexure of colon, 244
Splenium,
Spot, blind, 347

germinal, 286

light

yellow, 380, 365
Squamous. 15
Bteno'a ducts, 229
Stenson'8 foramina, 31
St< mum, 52
Stilling, canal of, 369
Btomach, 2.%
Styloid, 19
Substance, gray, 294

of Schwann, 294

medullar-.

white, 294
lantia gelatinosa Rolandi, 316

nipr.-i
Bulcl,
Sulcus spiralis, 886

tympanicu

Suprarenal capsules, 252
Surface, articular, 104

trochlear, 71
Sustentaculum tali, 93
Sutura, 39
Suture, basilar, 39

coronal, 39

intermaxillary, 39

laehrymoethmofrontal, 39

lambdoidal, 39

masto-occipital, 39

mastoparietal, 39

petro-occipital, 39

petrosphenoidal, 39

sagittal, 39

sphenoparietal, 39

squamoparietal, 39

squamosphenoidal, 39

zygomatic, 39
Sutures, facial, 39

of the orbit, 43

of the skull, 39

of hard palate, 409
Sylvius, fissure of, 304, 306
Sympathetic system, 335
Symphysis pubis, 85

of inferior maxillary, 29
Synarthrosis, 105
Synovial membranes, 104

Tarsus, 93

Taste, nerves of, 389
Taste goblets, 389
Tenit hippocampi, 311

semicircularis, 310
Teeth, 224, 415, 416
Tendo-oculi, 360
Tendons, 128
Tenon, capsule of, 360
Tentorium cerebelli, 296
Testes, 273

of the cerebrum, 315

descent of, 276
Thebesius, foramina of, 171
Thigh, 86
Thorax, 109
Thyroid axis, 188

cartilage, 254

gland, 251
Tongue, 388
Tonsils, 228
Trachea, 259
Tract, lateral, 388

optic, 306, 323
Tracts, olfactory, 306, 323
Tractus spiralis foraminulentus, 387
Tragus, 375

Triangle, Hesselbach's, 400
Trigonum urogenitale, 404

vesicae, 272
Trochanters of femur, 88
Trochlea, 71
Tube, Eustachian, 379
Tuber annulare (pons Variolli), 287,303

cinereum, 306
Tubercle, 4

genial, 36

lachrymal, 31

of Lower, 171

of tibia, 90
Tub' rosities, 4

of femur, 88

of humerus, 70

of ischium, 85
28

434

INDEX.

Tuberosities, maxillary, 31

Tubes of Henle (convoluted tubes), 268

spiral, of Sehachowa, 268
Tubuli lactiferi, 292

seminiferi, 274

uriniferi, 268
Tuft, Malpighian, 268
Tunica adventitia, 174

albuginea, 274

intima, 174

media, 174

Ruyschiana, 362

vaginalis, 274

vasculosa, 274
Tunics of eyeball, 360
Tutamina oculi, 356
Tympanum, 378
Tyson, glands of, 279, 292

Ulna, 72

Umbilical region, 234
Umbilicus, 234
Umbo, 380
Uraehus, 271
Ureters, 270
Urethra, 281, 291

bulb of, 281
Uterus, 283

masculinus, 281
Utricle, 281, 385
Uvea, 363
Uvula, 228

vesicae, 272

Vagina, 288

Valley of cerebellum, 301
Valsalva, sinuses of, 173
Valve, Eustachian, 171

Hasner, 375

ileocecal, 243

mitral, 173

of Baulin, 243

of Vieussens, 313

pyloric, 239

semilunar, 173

tricuspid, 172
Valves of Kirkring (valvulse conni-
ventes), 241

semilunar, 172, 173
Valvulae conniventes, 241
Vas aberrans, 276

deferens, 276
Vasa efferentia, 276

recta, 276

vasorum, 174
Vein, axillary, 214

basilic, 214

cephalic, 214

cerebral, 211

cerebellar, 211

femoral, 218

iliac, 217

median, 214

popliteal, 218

portal, 215

radial, 214

splenic, 215

subclavian, 213

suprarenal, 215

ulnar, 214

vertebral, 216
Veins, 174

azygos, 215

cardiac, 209

Veins, choroid, 211

hepatic, 215

iliac, 216, 217

innominate, 213

interlobular, 249

jugular, external, 212
internal, 210

of bone, 5 .

of Galen, 312

of head and neck, 211

of lower extremities, 218

of esophagus, 215

of suprarenal capsules, 215

of thymus, 252

of trachea and bronchi, 261

of the eye, 372

of the kidney, 268

of the larynx, 259

of the lung, 263

of the pancreas, 246

of the penis, 281

of the stomach, 240

of the thorax, 214

pulmonary, 218

saphenous, 218

spinal, 216

thyroid, 213

uterine, 284

without valves, 174
Velum, anterior medullary, 314

interpositum, 311
Vena cava, superior, 209

inferior, 215
Vena? comites, 174

proprise renales, 268

rectse, 268

vorticosse, 337
Venter of the ilium, 84

of the scapula, 65
Ventricle of the cord, 332

fifth, 315

fourth, 313

of the larynx, 257

third, 312
Ventricles, lateral, 308
Vertebra prominens, 59
Vertebras, 56
Verumontanum, 281
Vesalii, foramen, 23
Vesical, germinal, 286

Graafian, 286
Vesiculse seminales, 278
Vestibule, 291

of the ear, 383
Vidian canal, 24

nerve, 351
Vieussens, valve of, 314
Villi, 241
Viscera, covered by peritoneum, 237

partially, 237

wholly, 238
Vitellus, 286
Vocal cords, 257
Vomer, 35

Vortex of heart, 173
Vulva, 290

Walls of the tympanum, 378
Wharton's ducts, 229
Whorl of heart, 173
Willis, circle of, 186
Wings of the sphenoid, 23
Winslow, foramen of, 235
ligament of, 121

INDEX.

435

AVirsung, duct of, 246
"Wistar, pyramids of, 22
Wormian bones, -40
Wrisberg, cartilages of, 255
nerve of, 337

Zinn, zonula of, 369
Zona pellucida, 286
Zonula of Zinn, 369
Zygoma, 15, 28

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