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The human skeleton (Lewis).

STRUCTURE AND FUNCTIONS

THE BODY

A HAND-BOOK OF ANATOMY AND PHYSIOLOGY FOR

NURSES AND OTHERS DESIRING A PRACTICAL KNOWLEDGE

OF THE SUBJECT

ANNETTE FISKE, A. M.

GRADUATE OF THE WALTHAMXTRAINING SCHOOL FOR NURSES

ILLUSTRATED

PHILADELPHIA AND LONDON

W. B. SAUNDERS COMPANY

1911
K V\

PRINTED IN AMERICA

PRESS OF

V. 8. SAUNDER8 COMPANY
PHILADELPHIA

~JT4

Mil

TO MY FATHER

and •
TO DR. ALFRED WORCESTER

as those who have perhaps most helped me in

the formation and realization of my ideals

this book is affectionately dedicated

PREFACE.

ALTHOUGH there are already in existence many books
on anatomy and physiology for nurses, none with which
I am acquainted has seemed to me to provide in concise
form just the knowledge needed by the nurse in her
profession. Most of them, moreover, separate the anat-
omy from the physiology and all treat the different sys-
tems of tissues separately, first the bones, then the
muscles, and so on. These defects, as they seem to me,
I have attempted to correct not only by weaving the
physiology in with the anatomy, but by treating first
the general structures found throughout the body and
then describing the structure and function of each part
in detail. Thus, the first chapter is devoted to a descrip-
tion of the general structure of all the tissues, a separate
chapter being devoted, however, to the skin, its appen-
dages, and function, including the sense of touch. Then
the head with its bones, muscles, and organs of special
sense is described, while the brain is treated with the
rest of the nervous system, thus forming the connecting
link between the head and the body. In the same way
the back, chest, abdomen, pelvis, and extremities are
taken up in turn and the bones, muscles, blood-vessels,
nerves, and special organs of each, together with their
functions, described.

Although written more particularly for nurses I am
in hopes that this book may prove useful to any others
who may desire to acquire a practical knowledge of
anatomy and physiology.

Besides the usual text-books, I am much indebted
for material to notes taken in lecture courses given by

6 PREFACE.

Dr. Fred R. Jouett and Dr. F. J. Goodridge of Cambridge,
Mass., at the Cambridge School of Nursing, and by Dr.
Vivian Daniel of Watertown at the Waltham Training
School for Nurses.

I wish particularly to express my gratitude and ap-
preciation for the kind and helpful criticism given me
by Dr. Eugene A. Darling, Assistant Professor of
Physiology, Harvard College.

ANNETTE FISKE.

May, 1911.

CONTENTS.

CHAPTER I.

PAGE

COMPOSITION AND GENERAL STRUCTURE OF THE BODY ... 11
Chemical Constitution of the Body, 11— The Cell, 12—
The Fundamental Tissues of the Body, 13 — Epithelial
Tissue, 14 — Connective Tissue, 15— Structure of Bone,
17 — Bone Formation, 18 — Chemical Composition of
Bone, 18 — Classification and Function of Bones, 19 —
Joints, 20 — Muscle, 21 — Action of the Muscles, 23 —
Physiology of Muscle, 24 — Cilia, 27 — The Blood, 27—
Arteries, 27 — Veins, 28 — Capillaries, 28 — Lymphatic
System, 29 — Lymphatic Vessels, 31 — Lymphatic
Glands, 32— Lymph, 32— Glands, 35— Ductless Glands,
36 — Nervous Tissue, 36.

CHAPTER II.

THE SKIN, ITS APPENDAGES AND ITS FUNCTION 39

The Skin, 39 — Appendages of the Skin: Nails, 40 — Hair,
40— Sebaceous Glands, 41— Sweat Glands, 42— Sweat,
42 — Temperature Regulation, 43 — Fever, 45 — Sense of
Touch, 45— Touch Corpuscles, 46.

CHAPTER III.

THE CRANIUM AND FACE 48

The Cranial Bones, 48— Frontal Bone, 49— Parietal Bones,
49 — Occipital Bone, 50 — Occipito-frontalis Muscle,
51 — Temporal Bones, 51 — Sphenoid or Wedge Bone,
52 — Ethmoid Bone, 53 — Turbinated Bones, 53 —
Ossification of Sutures, 53 — Bones of the Face, 53 —
Superior Maxillary Bones, 54 — Antrum of Highmore,
54 — Malar or Cheek Bones, 54 — Lachrymal Bones, 54 —
Palate Bones, 54 — Nasal Bones, 55 — Vomer, 55 — In-
ferior Turbinated Bones, 55 — Inferior Maxillary Bone
or Lower Jaw, 55 — Sublingual Gland, 56 — Submaxil-
lary Gland, 56.

CHAPTER IV.

THE ORGANS OF SPECIAL SENSE 57

The Nose, 57 — The Sense of Smell, 58 — The Mouth,
59 — The Hyoid Bone, 60 — The Teeth, 60 — The Sense

8 CONTENTS.

PAGE

of Taste, 61 — Salivary Glands, 61 — The Tonsils, 62 —
The Ear, 63 — Eustachian Tubes, 63 — Sensation of
Hearing, 65 — The Eye, 66 — Lachrymal Gland, 68 —
Coats of the Eye, 68 — Light Rays and Sight, 70 — Ac-
commodation, 72 — Color Perception, 73.

CHAPTER V.

THE NERVOUS SYSTEM 75

The Cerebrum, 75— The Cerebellum, 78— Pons Variolii,
78— Medulla Oblongata, 78— Spinal Cord, 79— Brain-
centers, 81 — Motor Tract, 82 — Sensory Tract, 82 — Re-
flex Action, 83 — Cranial Nerves, 83 — Spinal Nerves, 84
— Brachial Plexus, 85 — Sacral Plexus, 85 — The Sym-
pathetic System, 87 — The Sympathetic Nerves, 87.

CHAPTER VI.

THE BACK 83

The Spine, 88— The Vertebrae, 88— Muscles of the Neck,
92— Muscles of the Back, 93.

CHAPTER VII.

THE CHEST 98

The Sternum, 97 — The Ribs, 97 — Costal Cartilage *,
98 — Muscles of the Chest, 98 — Diaphragm, 98 —
Mammary Glands, 100.

CHAPTER VIII.

THE HEART AND CIRCULATION 101

The Heart, 101 — The Pericardium, 101 — Cavities of the
Heart, 103 — The Endocardium, 103 — The Valves of
the Heart, 103 — Circulation, 105 — Circulation in the
Fetus, 106 — Arteries, 107 — Veins, 109 — Portal Circu-
lation, 109 — Pulmonary Circulation, 110 — Nerves of the
Heart, 110 — Heart Sounds, 111 — The Heart Beat,
111 — Factors Affecting Circulation, 112 — The Pulse,
113 — Blood Pressure, 114 — Nerve Supply of the Blood-
vessels, 115 — The Blood, 116 — Composition of the
Blood, 116— Coagulability of the Blood, 117— Blood-
corpuscles, 118.

CHAPTER IX.

THE LUNGS AND RESPIRATION 121

The Larynx, 121— The Trachea, 123— The Thyroid
Gland, 124— The Thymus Gland, 124— The Bronchi,
125— The Lungs, 125— The Pleura, 125— The Medias-
tinum, 126 — Respiration, 127 — Air, 129 — Respiratory
Sounds, 129 — Changes in Air in Lungs, 129 — Effect of
Respiration on Blood, 130 — Nervous Mechanism of
Respiration, 130 — Variations in Respiration, 131.

CONTENTS. 9

CHAPTE]

PAGE

THE ABDOMEN AND THE ORGANS OF DIGESTION AND EX-
CRETION IV *T^ • • 132

The Abdominal Cavity, 132 — Muscles of the Abdomen,
132 — The Peritoneum, 134 — Abdominal Regions, 134
—Salivary Digestion, 136— The Pharynx, 136— The
Esophagus, 138— The Stomach, 138— Gastric Diges-
tion, 139 — Vomiting, 140 — Intestinal Canal, 141 — The
Small Intestine, 142 — Intestinal Digestion, 143 — Ab-
sorption in Intestine, 144 — The Large Intestine, 145 —
Food and Metabolism, 147— The Liver, 149— The Gall-
bladder, 152— The Pancreas, 153— The Spleen, 153—
The Suprarenal Capsules, 154 — The Kidneys, 155 —
The Urine, 156— The Ureters, 159— The Bladder and
Urethra, 159.

CHAPTER XI

THE PELVIS AND THE GENITAL ORGANS 161

The Pelvis, 161— The Male Generative Organs, 164— The
Prostate Gland, 164— The Testes, 165— The Penis,
165 — The Female Generative Organs, 165 — The
Ovaries, 165 — The Fallopian Tubes, 166 — The Uterus,
167 — The Vagina, 168 — The External Genitalia in the
Female, 169 — The Vulva, 169 — The Mons Veneris,
169 — The Labia Majora, 169 — The Labia Minora, 170
— The Clitoris, 170 — The Meatus Urinarius, 170 —
The Hymen, 170 — The Fourchette, 170 — The Perineal
Body, 170 — The Perineum, 170.

CHAPTER XII.

THE UPPER EXTREMITIES 171

The Shoulder Girdle, 171— The Clavicle, 171— The
Scapula, 173 — Shoulder Muscles, 174 — The Humerus,
175— Upper Arm Muscles, 176— The Ulna, 177— The
Radius, 178— The Wrist, 180— The Hand, 181— Meta-
carpals, 181 — Phalanges, 181 — Muscles of the Forearm,
182 — Muscles of the Hand, 184 — Joints of the Upper
Extremity, 185 — Blood Supply of the Upper Extrem-
ity, 185 — Nerves of the Upper Extremity, 186.

CHAPTER XIII.

THE LOWER EXTREMITIES 187

The Femur, 187 — Thigh Muscles, 189 — The Patella, 192 —
Joints of the Lower Extremity, 192 — The Tibia, 194
—The Fibula, 194— The Ankle, 195— The Foot, 195
— Metatarsals, 195 — Phalanges, 195 — Muscles of the
Leg, 196 — The Blood Supply of the Lower Extremity,
198 — Nerves of the Lower Extremity, 199.

INDEX . . 201

STRUCTURE AND
FUNCTIONS OF THE BODY.

CHAPTER I.

COMPOSITION AND GENERAL STRUCTURE OF THE

BODY.

Anatomy is the study of the physical structure and
physiology the study of the normal functions of the
human body.

Chemical Constitution of the Body. — In the body only
twenty elements have been found. These include car-
bon, oxygen, hydrogen, nitrogen, sulphur, phosphorus,
calcium, magnesium, manganese, chlorin, potassium, and
fluorin. For the most part they appear in very complex
and highly unstable combinations, though oxygen and
nitrogen may be said to exist uncombined in the blood,
alimentary canal, and lungs. Hydrogen also occurs in
simple form in the alimentary canal, but as the result
of fermentation, not as an element of the body.

Of the organic compounds some contain nitrogen and
some do not. The most important of the former are the
proteins, which are found only in living bodies and consist
of carbon, hydrogen, oxygen, nitrogen, and sulphur
combined in very similar proportions. The important
proteins in the body are the serum albumen and fibrin
found in the blood, myosin in muscle, globulin in the
red blood-corpuscles, and casein in the milk. Similar to
the proteins but capable of passing through membranes

12 GENERAL STRUCTURE OF THE BODY.

are the peptones, the final result of protein digestion,
from which the albuminoids differ in that they contain
no sulphur. Ferments containing nitrogen exist in all
the cells of the body, though more particularly in those of
the digestive organs, and the coloring matters, as the
bilirubin of the bile, are nitrogenous.

The organic substances that do not contain nitrogen
are the carbohydrates or starches, the hydrocarbons or
fats, and the acids, of which the most important is cnr-
bon dioxide, given off by the lungs.

The inorganic substances are water, which forms a
large percentage of all the tissues and from one-fourth
to one-third of the whole body weight, sodium chloride
or common salt, which plays an important part in keep-
ing substances in solution, potassium and magnesium
chloride, and hydrochloric acid, found in the stomach.

The Cell. — Although the body is a very complex organ-
ism, the cell is its unit or foundation. In fact, the body
begins life as a single protoplasmic cell, the ovum, which
is frequently compared to the amoeba, a microscopic
animal consisting of a single cell of protoplasm or living
substance — a substance not well understood as yet — but
possessing practically all the functions of the human body.
For, although it has no organs and is homogeneous in
structure, the amoeba can move by throwing out a pro-
cess, and can surround and absorb food, which it builds
up into new tissue, discarding the waste. The ovum,
however, differs' from the amceba in that it has a trans-
parent limiting membrane and contains a darker spot,
the nucleus. This in turn contains another smaller spot,
the nucleolus, while through the protoplasm, which is
semi-fluid, extends a fine network that seems to hold it
in place.

The ovum is very small, about y^-y inch in diameter,
and after fertilization grows by segmentation, the nucleus
dividing in two and the protoplasm grouping itself anc\v
about the two nuclei. This division continues, each cell
dividing and forming two, or sometimes four, new cells,

GENERAL STRUCTURE OF THE BODY. 13

all of which at first appear alike. By degrees, however,
differentiation takes place and different groups of cells
assume different characteristics. Thus the various
tissues are gradually developed, each with a structure
and a function of its own, and are distributed among the
various organs, each organ consisting of several tissues.
During the process of growth and even after full growth
of the body is attained old cells are continually dying and
being replaced by new ones.

The typical cell is circular, but through being squeezed
together in the tissues or for some other reason the cells
vary in shape in different parts, being at times hexagonal,
spindle-shaped, or columnar. Yet, whatever their differ-
ences in shape or other characteristics, they all live the
same sort of life. All protoplasm absorbs oxygen when
it comes in contact with it and in the process of combin-
ing with it is in part burned or oxidized, with the conse-
quent setting free of heat and other forms of energy and
the formation of carbon dioxide. So long as the body
is alive, therefore, whether it -is in a state of activity or of
rest, it is the seat of constant chemical change through-
out all its cells, and to these chemical changes are due all
the forms of energy manifested by the body. For energy
is never destroyed, though it may appear in a different
form, and the elements of the human body are so com-
bined that their energy may be liberated and manifested
in the different functions the body exhibits.

The fundamental tissues of the body are the epithelial
tissues, the connective tissues, including the cartilagin-
ous and bony tissues, and the muscular and nervous
tissues. Of these the epithelial tissues serve as a protec-
tion to the surface of other tissues; the connective tissues
together form a framework for the support and general
protection of the other tissues; while energy is expended
by muscular and nervous tissue, the latter directing the
former in its movements. All the tissues are inter-
dependent and the organs work together. Besides cells
every tissue contains a certain amount of lifeless matter,

14 GENERAL STRUCTURE OF THE BODY.

the intercellular substance, which was at some time pro-
duced by the cells.

In epithelial tissue there is little intercellular substance,
the cells being close together and arranged generally as a
skin or membrane covering external or internal surfaces.
When there are several layers of cells, the deepest are
columnar in shape and the others become more and more
flattened and scale-like as they approach the surface,
where they are gradually rubbed off and replaced by the
growth of new cells from below. This stratified epithe-
lium, as it is called, is found wherever a surface is exposed

FIG. 1. — Epithelium: 1, pavement epithelium; 2, columnar epithelium; 3,
ciliated epithelium; 4, stratified epithelium.

to friction, as in the skin and in the mucous membrane of
the mouth, pharynx, and esophagus, and in that of the
vagina and the neck of the uterus. In simple epithelium,
where there is only a single layer of cells, the cells may be
pavement or hexagonal, columnar, glandular, or ciliated,
according to their different functions. The flat pave-
ment cells occur where a very smooth surface is required,
as in the heart, lungs, blood-vessels, serous cavities, etc.
None of these surfaces communicate directly with the
external surface of the body and the name endothelium is
substituted for epithelium. The columnar form of cell in
the intestine facilitates the passage of leucocytes between
the cells. In glandular epithelium the cells vary accord-
ing to the gland in which they occur, their protoplasm

^. HOSp/7>

GENERAL STRUCTURE Qt\JHE BODY. 15

TRAINING SCHC

being filled with the material the gland secretes. Finally,
ciliated epithelium is composed cH^columnar cells with
cilia or little hair-like processes upo
which serve to send secreted fluids and other matters
along the surfaces where they occur, as in the air pas-
sages, parts of the generative organs, the ventricles of
the brain, and the central canal of the spinal cord.

Connective tissue has a great deal of intercellular sub-
stance. One form, areolar tissue, is composed of a loose
network of fine white fibers with a few yellow elastic
fibers interspersed and with cells lying in the spaces

Pavement cell.
Pear-shaped cell.

Interstitial cell.

FIG. 2. — Section of bladder epithelium. (Hill.)

between the fibers. It connects and surrounds the differ-
ent organs and parts, holding them together, yet allowing
free motion, and is one of the most extensively distrib-
uted of the tissues. It is continuous throughout.

Closely allied to the areolar is the fibrous tissue, in
which the white fibers lie close together and run for the
most part in one direction only. This is found in liga-
ments, joints and tendons, as also in such fibrous pro-
tective membranes as the periosteum, dura mater, the
fascia of muscles, etc. Fibrous tissue is silvery white in
appearance and is very strong and tough, yet pliant.
It is not extensile.

Elastic tissue, on the other hand, has a large predomi-
nance of yellow elastic fibers and is very extensile and
elastic, though not so strong as the fibrous. It is found
in the walls of the blood-vessels, especially the arteries,

16 (iKXKKAl. 8TBUCTURE OF THE BODY.

in the walls of the air tubes, in (lie ligaments of the
spine, etc.

Fiiltij or W///JO.XT ttNtiuc is formed by the deposit of fat
in the cells of the areolar tissue and is found in most
pails where the areolar tissue occurs, though it varies
largely in amount in different parts. It is found pretty
generally under the skin, fills in inequalities about vari-
ous organs and about the joints, and exists in large quan-

d-^ :-i^V-'^. ' -'

FIG. 3. — Adipose tissue (Leroy): a. Fibrous tissue; 6, fat cells; c, nucleus of
fat cells; d, fatty acid crystals in fat cells.

titles in the marrow of the long bones. In moderate
amounts it gives grace to the form and constitutes an
important reserve fund.

Cartilage consists of groups of nucleated cells in inter-
cellular substance. It is very firm, yet highly elastic, and
serves in the joints to break the force of concussion of the
harder and less elastic bones. Except when it occurs at
the end of a bone, it is covered with a membrane called
the perichondrium, which carries its blood supply. In
the nose, ear, larynx and trachea it serves to give shape,
to keep the passages open, and to afford attachment for

GENERAL STRUCTURE OF THE BODY.

muscles. Most of the skeleton of the fetus consists of
cartilage, which later develops into bone.

Bone. — In bone the intercellular tissue is rendered
hard by the deposit of mineral salts, the resulting material
being of great strength and rigidity. The texture may
be close and dense like ivory or open and spongy, the
difference lying merely in the fact that the one has fewer
spaces between the solid particles than the other. There
is usually a hard, compact layer on the exterior of the
bone, as that is where the greatest cross-strain comes,
especially in the long bones, while within is the cancellous
or spongy tissue, which gives lightness to the bone and
is capable of withstanding enormous pressure, though
it can bear little cross-strain.

Structure of Bone. — The hard substance in bone is
always arranged in lamellae or bundles of bony fibers,

Haversian canal.

Lacuna and canaliculi.

FIG. 4. — Cross-section of compact bone tissue. (After Sharpey.)

which in cancellous tissue meet to form a kind of lattice-
work, while in the dense tissue they are generally ar-
ranged in rings about the Haversian canals, channels
through which the blood-vessels pass through the bone
longitudinally. Between the lamellae are spaces called
lacunce, in which lie branched cells, the spaces being
connected with each other and with the Haversian
canals by numerous tiny canals or canaliculi, by which
2

18 GENERAL STRUCTURE OF THE BODY.

nutrient material finds its way from the Haversian canals
to all parts of the bone.

Within the bone is the medulla or marrow, which is of
two varieties: the yellow, which is largely fat and is found
in the long bones of adults, and the red, which is nearly
three-fourths water and is found in most of the other
adult bones and in the bones of the fetus and of the
infant.

Lining the medullary and cancellous cavities is a
delicate connective tissue lining, the endosteum, which
contains many bone-forming cells, while on the outside
of the bone, except at the articular ends, is the perios-
teum with its outer protective layer and its inner vas-
cular layer containing osteoblasts or bone-forming cells.
The periosteum is essential for the growth of new bone
where the old bone has died, and if the periosteum is
removed from healthy bone the part beneath is liable to
die, as it is by the constant growth of the osteoblasts
that the bone grows and is renewed. In the repair of
broken bones tissue is formed between and around the
broken ends.

Bone Formation. — Most of the skull and face bones
begin as membranes of connective tissue, that is, are
formed in membrane. Bones are also formed in carti-
lage, the bone formation in this case beginning from
centers of ossification, where the deposit of lime salts in
the intercellular substance begins, the salts coming to
the centers dissolved in the plasma. Such a center of
growth in a bone is called the epiphysis and is separated
from the main part of the bone or diaphysis by cartilage
until full growth is attained, when ossification becomes
complete. So in surgery, in working on the bones of
children, part of the epiphysis should always be left for
the sake of future growth. The outer shell of compact
tissue is deposited by the periosteum.

Chemical Composition of Bone. — Chemically bone is
composed of about one-third organic or animal matter,
largely gelatine, and two-thirds inorganic matter, includ-

GENERAL STRUCTURE OF THE BODY. 19

ing various salts of calcium, magnesium, and sodium.
In young children the animal matter predominates and
the bones are soft and often bend instead of breaking,
only the outside shell on one side giving way, as in " green-
stick" fracture. In rickets there is a deficiency of lime
salts, but the increased brittleness of the bones in old
age is due, not to increase of mineral matter, but to the
less spongy texture of old bones.

Classification and Function of Bones. — There are in the
body some two hundred bones, which may be classified
as long, short, flat, and irregular. Occasionally an ir-
regular bone develops in a fontanelle, the membranous
opening at the juncture of the sutures of the skull.
This is known as a Wormian bone. It is not, however,
included in the two hundred, as are not the sesamoid
bones or bones developed in tendons, with the exception
of the patella or knee-cap.

Long bones are developed in cartilage and consist of a
shaft, two extremities, and various processes. They are
more or less curved to give them strength and grace.
They serve as supports and act as levers for purposes of
motion and the exercise of power. Since a hollow cyl-
inder is just as strong as a solid one of the same size, the
weight coming only on the outer shell, the great bones
which are accountable for weight and which need to be
light themselves have hollow shafts, composed chiefly of
compact tissue with a central medullary canal. The
ends, however, are expanded in order to make better
connection at the joints and to afford broad surfaces
for muscular attachment-, cancellous tissue being used
in them for lightness and strength. The large spongy
ends also give elasticity and lessen jar, and by bringing
the tendons to the bone at a greater angle increase their
effectiveness. Blood is brought to the long bones not
only by the vessels of the periosteum but by the medul-
lary artery, which penetrates the compact tissue by the
nutrient foramen and divides into an ascending and a
descending branch.

20 GENERAL STRUCTURE OF THE BODY.

Short bones are spongy throughout. They are used
for strength and where little motion is required.

Flat bones are composed of two thin layers of compact
tissue with a varying amount of cancellous tissue be-
tween, and are for protection and muscular attachment.
The cancellous material between the two layers or tablets
of the skull is called the diploe.

Eminences and depressions occur on bones and when
they are not articular are for the attachment of ligaments
and muscles. If they are articular, they help to form
joints.

As a whole the bony framework serves to keep the
soft parts in place, to support and protect them, and to
aid in locomotion. The bones of the head and trunk
support and protect organs; those of the arms are for
tact and prehension; those of the lower extremities are
for support and locomotion.

Normally bones have little sensibility, but when in-
flamed they are extremely sensitive and painful.

Joints. — The bones are connected with and move upon
one another by means of joints. These joints are of
three kinds: 1. Immovable, where the adjacent margins
of the bones are closely applied, with little fibrous tissue
between, as in the sutures of the head; 2. those with
limited motion, which are very strong, the parts being
connected with tough fibre-cartilage; and 3. freely mov-
able. In this last group the articulating surfaces are
covered with cartilage, which again is lined with a deli-
cate synovial membrane which secretes a small amount
of lubricating fluid, the synovial fluid, to reduce friction.
Their surfaces are also sometimes deepened by the pres-
ence of interarticular fibro-cartilages. Bursse or sacs of
synovial membrane occur outside the joints under ten-
dons and ligaments to reduce friction.

The nature and extent of the motion of a joint is
defined and the bones are held together by strong bands
of fibrous tissue or ligaments, these ligaments being more
fully developed in joints where there is great freedom of

GENERAL STRUCTURE OF THE BODY. 21

motion or where there is great weight to be supported.
In a ball-and-socket joint, such as the hip, there is a
ligament in the form of a strong capsule which surrounds
the joint on all sides and limits its motion, while hinge
joints, like the elbow, and pivot joints, such as that
formed by the atlas on the axis, have lateral ligaments
that allow of freer motion. In the shoulder-joint, which
is the most freely movable joint in the body, the capsular
ligament is very lax.

In general the kinds of motion possible in joints may
be said to be flexion, extension, abduction, adduction,
circumduction, and rotation.

When much violence is applied to a joint and no dis-
location results, as in a sprain, there is often much
stretching and even laceration of the ligaments.

Muscle. — The flesh, which forms a large proportion of
the weight of the body, consists of muscular tissue. Of
this two kinds are found: 1. The striated or striped
muscle of animal life, which is under the control of the will
and so is known as voluntary muscle, and 2. the unstriped
or smooth muscle of organic life over which we have no
control, that is, the involuntary muscle. Each fiber of
striped muscle has an elastic, membranous sheath, the
sarcolemma, and consists of rod-shaped cells with a
nucleus along the edge, set end to end and having cross-
wise striations. In unstriated muscle the fibers, which
have no sarcolemma, consist of oval or spindle-shaped
cells, with a nucleus much smaller than that of striped
muscle and situated in the middle. In both kinds of
muscle the fibers are bound together with connective
tissue and blood-vessels into fasciculi or bundles, and
many bundles go to make up a muscle. The muscle in
turn has a connective tissue envelope or sheath, the
fascia. These fasciae are found throughout the body, the
superficial ones being just beneath the skin, while the
deep ones not only form sheaths for the various mus-
cles but form partitions between them and serve to
strengthen their attachments. The striped muscles are

GENERAL STRUCTURE OF THE BODY.

those of motion, while the unstriped occur in the hollow
organs, surrounding the cavity and in some cases lessen-
ing its capacity by their contraction.

An intermediate form of muscle known as cardiac
muscle occurs in the heart. Here the fibers have stria-
tions but the nucleus is generally in the middle of the
cell and the fibers branch and run together.

FIG. 5. — Voluntary muscle (Leroy). A, Three voluntary fibers in long sec-
tions: a, three voluntary muscle fibers; 6, nuclei of same ;c, fibrous tissue between
the fibers (endomysium) ; d, fibers separated into sarcostyles. B, Fiber (diagram-
matic): a, dark band; b, light band; c, median line of Hensen; d, membrane of
Krause; e, sarcolemma; /, nucleus. C: a, Light band; b, dark band; c, contract-
ing elements; d, row of dots composing the membrane of Krause; e, slight
narrowing of contracting element aiding in production of median line of Hensen.

In life muscle appears more or less translucent and
is contractile and alkaline, but in death it loses its trans-
lucency and becomes rigid, at the same time giving off
in decomposition much carbon dioxide, so that its re-
action is acid. This phenomenon of the muscles be-
coming rigid in death is called rigor mortis and occurs
generally a few hours after death, though it may come

GENERAL STRUCTURE OF THE BODY. 23

at once or be considerably delayed. It may last any-
where from a few moments to several days but gener-
ally lasts from twenty-four to thirty-six hours. It is
probably due to the formation in the muscle of myosin,
a substance which probably comes from myosinogen
in the living muscle and which is closely akin to the
fibrin of blood. Probably the myosin or what precedes
it causes clotting of the muscle just as fibrin or what
precedes it causes clotting of the blood.

The muscles vary in shape in different parts of the
body, being long and slender in the limbs and broad and
flat in the trunk. They are attached chiefly to bones

FIG. 6. — Three voluntary muscle fibers from an injected muscle, showing
network of blood capillaries. (Hill.)

but also to cartilages, ligaments, and skin, either by
means of tendons, which are cords or bands of white
inelastic fibrous tissue, or by means of aponeuroses,
membranous expansions of the same nature. Most
voluntary muscles consist of a belly and two ends or
tendons. The origin is the fixed point from which it
acts while the movable^ point upon which it acts is
known as its insertion.

Action of the Muscles. — When attached to bones, mus-
cles are distributed in three ways: 1. When it is neces-
sary to produce much motion rapidly, a short muscle is
used. 2. When a part needs to be moved far and
much contraction on the part of the muscle is, there-
fore, needed, the muscle is very long, as in the case of
the sartorius muscle, which shortens half its length. 3,

24 GENERAL STRUCTURE OF THE BODY.

Finally, where less distance has to be covered but
greater power is required, tendons are used, as in this
case the contraction is powerful but does not carry
the part far.

In performing the mechanical work of the body the
muscles are aided by the fact that the bones, to which
they are largely attached, are set together loosely and
form a set of levers, on which the muscles act to perform
certain definite acts. All three classes of levers occur:
1. where the fulcrum is between the weight and the
power, as in the case of the head, which is balanced by
the muscles of the neck on the vertebrae; 2. where
the weight is between the fulcrum and the power, as
when a person raises himself upon his toes; and 3.
where the power is between the fulcrum and the weight,
as when the biceps is used to raise a weight held in the
hand. The erect position of the body is difficult to
maintain because the center of gravity is high up, and it is
by the contraction of many muscles in the legs, thighs,
back, abdomen, and neck that the body is balanced
upright upon the feet.

Physiology of Muscle. — Irritability or sensitiveness to
stimulation and contractility or the power to contract
are the two most important functions of muscle. Con-
traction occurs in response to nervous energy brought
by the nerves, a nerve filament going to each muscle
fiber, into which it plunges, its substance being lost and
its sheath becoming continuous with that of the mus-
cle fiber. Any irritant, as heat, electricity, etc., when
applied to the nerve, causes the muscle to contract.
Moreover, muscle has an irritability of its own and
can contract independently of the nervous system. In
contracting it shortens and thickens, bringing the two
ends closer together, and becomes firm and rigid. The
amount of contraction depends upon the strength of the
stimulus and the irritability of the muscle. The mini-
mal stimulus is the least stimulus that will cause a con-
traction and the maximal is one that will cause the great-

GENERAL STRUCTURE OF THE BODY. 25

est contraction. The work done depends in like manner
upon the strength of the stimulus. During contraction
certain sounds are given off called muscle sounds, which
can be heard with the stethoscope but have no special
significance.

The muscles which have the greatest power of rapid
contraction are generally attached to levers. Indeed,
striated muscle is characterized by the rapidity and
strength with which it works, though its rhythmic mo-
tion is slight. Smooth muscle, on the other hand, is
characterized by its great force, considerable rhythm,
considerable tone, and slight rapidity, that is, its con-
traction is slower and lasts longer than that of striated
muscle. Cardiac muscle is characterized by great rhythm
and force, fair rapidity, and slight tonicity, tonicity
being the amount of tone or readiness to work. For
even in sleep muscle is always in tone, that is, ready to
do its work. It is this that makes the difference in ap-
pearance between a living and a dead person and en-
ables one to spring to his feet at night if he hears a noise,
a thing he could not do if his muscles were wholly re-
laxed. Thus, rapidity is the great function of striated,
tonicity of smooth, and rhythm of cardiac muscle. In
paralysis the muscles droop and lose their tone. Mus-
cles are frequently the seat of rheumatic disorders.

When set free, potential energy accomplishes work.
In muscle there is a good deal of potential energy,
which is set free as heat and as work accomplished.
Even when the muscles are at rest, chemical changes are
going on and heat is being produced, though more heat
is produced when they are functioning. If the body de-
pended upon its gross motions for all its heat it would
grow cold while a person rested. The respiratory or-
gans, however, and the heart are always working and
chemical changes are constantly taking place.

Ordinarily a muscle has some object in contracting,
such as the raising of a load, and it contracts voluntarily
more or less according to the weight of the load. The

26 GENERAL STRUCTURE OF THE BODY.

amount of work done is calculated in foot-pounds or
gram-meters, that is, the energy required to raise one
pound one foot or one gram one meter. As a rule the
muscles with the longest fibers, as the biceps, do the
most work and those with a large number of fibers do
more than those with less. It has been calculated that
whereas an engine gives back one-twelfth of the energy
of the coal consumed, muscle liberates one-fourth of the
energy brought to it in the form of food. During ac-
tivity the glycogen or sugar in the muscle is used up and
the muscle becomes more acid, owing to the lactic acid
that is formed. The carbon is taken in and carbon di-
oxide given off. Nitrogen puts the muscle in condition
to do its work but is not so much used up in the work as
is the carbohydrate material. So it is the non-nitrogen-
ous matter that does the work and any increase in urea,
the end-product of protein metabolism, is mere wear and
tear.

Sudden heat or cold causes muscular contraction and
moderate heat favors both muscular and nervous irri-
tability. Moderate cold, however, lessens the force of
contraction and below zero muscle very largely loses
its irritability without necessarily becoming rigid.

While well supplied with blood, muscle will contract
without fatigue, but if the blood supply is shut off, it
soon loses its irritability and becomes rigid. The more
a muscle is used in moderation the more it develops, but
after it has done a certain amount of work it becomes
exhausted, losing its irritability or power to respond to
stimuli and later becoming rigid. Such fatigue is due
to the production of certain poisonous waste products
which have a paralyzing effect on the nerves and which
are ordinarily gradually carried away in the blood, but
which sometimes, if produced to excess, accumulate
too fast for the blood wholly to remove them. Usually
the nerve becomes exhausted first and the muscle sub-
stance later. So long as it is connected with the nervous
system a muscle will respond to stimuli, but when the

GENERAL STRUCTURE OF THE BODY. 27

nerve becomes tired, degeneration is more rapid. In
fact, the degree of exhaustion is determined by several
factors, as by relation to the central nervous system,
variations in temperature, blood supply, and functional
activity, the process being more rapid in warm than in
cold blooded animals.

Cilia. — A few motions are accomplished by tissue that
is not muscular, as in the case of the cilia attached to the
cells of the respiratory tract, which lie flat on the free
surface and then lash forward, serving in the air cells to
keep the air in motion and in the tubes to send secretions
from below upward and outward and to keep out for-
eign bodies. Cilia are also found in the female genital
tract, where they aid the passage of the ovum from the
ovary to the womb. They act together, though appar-
ently not governed by the nervous system. As in the
white corpuscles of the blood, whose motion also is not
muscular, the changes that take place in ciliated epithe-
lium are probably about the same as those in muscular
tissue, that is, contractile.

The Blood. — To most of the tissues just described
nourishment is brought in the blood, which cir-
culates through the body in a system of hollow tubes,
the arteries and veins, whence it is distributed through
the agency of the lymphatic system. There are no blood-
vessels, however, in the epidermis, epithelium, nails,
hair, teeth, nor in the cornea of the eye. The vessels
that carry the blood from the heart are called arteries,
those that return it veins. The former begin as large
vessels and gradually decrease in size; the latter begin
as small vessels and form larger and larger trunks as
they approach the heart.

The arteries have three coats: 1. a thin, serous coat,
the internal or intima; 2. a middle or muscular coat, and
3. an external coat of connective tissue. The middle
coat is the thickest and is the one that prevents the walls
from collapsing when cut across. Except in the cra-
nium, each artery is enclosed in a sheath with its vein

28 GENERAL STRUCTURE OF THE BODY.

or veins, the venae comites. Usually the arteries occupy
protected situations and are straight in their course.
Where a vessel has to accommodate itself to the move-
ments of a part, however, it may be curved, as in the case
of the facial artery which is curled on itself to allow for
movements of the jaw. They anastomose or communi-
cate freely with one another, thus promoting equality of
distribution and pressure and making good circulation
possible even after the obliteration of a large vessel.

The veins have three coats like the arteries, but they
are not so thick and the muscular coat is not so highly
developed, so that the walls collapse when cut and have
no elasticity. There are constrictions on the surface
of many of the veins due to the presence of valves.
These valves are formed of semi-lunar folds of the lining
membrane and are arranged in pairs. They serve to
prevent the blood, whose circulation in the veins is
sluggish, from flowing back.

There are two sets of veins, the superficial and the
deep, which communicate with each other. In fact,
all the veins, large and small, anastomose very freely,
especially in the skull and neck, where obstruction
would result in serious trouble, throughout the spinal
cord, and in the abdomen and pelvis. The deep veins
accompany the arteries in their sheath, while the
superficial ones have thicker walls and run between the
layers of the superficial fascia under the skin, terminating
in the deep veins. In the skull the venous channels
take the form of sinuses, formed by a separating of the
layers of the dura mater, with an endothelial lining that
is continuous with that of the veins.

The capillaries are intermediate between the arteries
and the veins, the final division of the arteries and the
first source of the veins. They are tiny vessels with
but a single coat, continuous with the innermost coat
of both arteries and veins and consisting practically of
one layer of cells with a small amount of connective tis-
sue between. They spread in a great network through-

GENERAL STRUCTURE OF THE BODY. 29

out the tissues, forming plexuses and being especially
abundant where the blood is needed for other purposes
than local nutrition, as in the secreting glands. Their
diameter is so small that the red corpuscles have to pass
in single file and may even then be squeezed out of shape.
As they have no muscular tissue in their walls, they have
no power of contracting. Their walls, however, like
those of the smaller arteries and veins, are porous and by
virtue of this quality they play an important part in the
economy, since in them the exchange takes place be-
tween the tissues and the blood.

The arteries in general carry freshly oxidized blood
and the veins blood from which the oxygen has been
largely used up and which contains waste material.
In the pulmonary system, however, the case is re-
versed, the pulmonary arteries conveying venous blood,
as it is called, from the heart to the lungs to be oxi-
dized and the veins returning the blood after it has
received its new supply of oxygen.

The pumping of the blood through the arteries is as-
sisted by the contractions of the muscular coat, while
the elastic tissue, of which it contains a certain amount,
gives elasticity to the walls and enables them to stretch
and so to accommodate the larger blood supply forced
into them at each beat by the heart. The walls of the
veins have not the power of contracting and the blood
is pushed through more by gravity and the action of the
arteries than by any action of their own.

The walls of all the vessels are nourished by tiny
blood-vessels in the outer^ coat, known as vasa vasorum,
and the nerves that regulate the action of the arteries
are the vasomotor nerves from the vasomotor center
in the medulla. Sufficient impulse goes from this cen-
ter to the blood-vessels all the time to keep them some-
what contracted, in a state of tone, that is, which is
increased or diminished as the blood supply is to be
diminished or increased.

Lymphatic System. — The lymphatic system also ex-

30 GENERAL STRUCTURE OF THE BODY.

tends throughout the body and consists of a system of
channels, spaces, and glands very closely related to the
circulatory system and containing a fluid called lymph.
There are three principal parts to the system: 1. the
lymph spaces, which are open spaces, with no definite
walls, in the connective-tissue framework of the body,
more frequent near arteries and veins and especially so

FIG. 7. — Diagram showing the course of the main trunks of the absorbent
system: the lymphatics of lower extremities (D) meet the lacteals of the intestines
(LAC) at the receptaculum chyli (R.C.), where the thoracic duct begins. The
superficial vessels are shown in the diagram on the right arm and leg (s), and the
deeper ones on the left arm (D). The glands are here and there shown in groups.
The small right duct opens into the veins on the right side. The thoracic duct
opens into the union of the great veins of the left side of the neck (T). (Yeo.)

among the capillaries; 2. the lymph capillaries or small
vessels which connect the lymph spaces; and 3. the
lymphatic vessels, of which there is a deep and a super-
ficial set, the latter accompanying the superficial veins
on the surface of the body, the former accompanying
the deep blood-vessels.

The lymph spaces are generally small, though there

GENERAL STRUCTURE OF THE BODY.

are some large serous cavities, such as the abdomen,
that may be considered as extended lymph spaces.

The lymphatic vessels have delicate, transparent walls,
with three coats like the arteries, though much thinner,
and anastomose even more freely than the veins. They
have a beaded appearance due to the presence of numer-

a.l.

FIG. 8. — Diagram of a lymphatic gland, showing afferent (a. Z.) and efferent
(e. Z.) lymphatic vessels; cortical substance (C); medullary substance (M)\ fi-
brous coat (c) ; sending trabeculse (tr) into the substance of the gland, where they
branch, and in the medullary part form a reticulum; the trabeculse are sur-
rounded by the lymph path or sinus (Z. s.), which separates them from the
adenoid tissue (Z. h.). (Sharpey.)

ous valves, which form constrictions on their surface.
The right lymphatic duct, which is only about an
inch long, drains all the lymphatics of the right half of
the upper part of the trunk, the head, and the neck ap-
proximately, while the thoracic duct drains those of the
rest of the body. The latter, which is the largest vessel
of the system, begins opposite the second lumbar ver-

GENERAL STRUCTURE OF THE BODY.

tebra with a bulb-like reservoir for the lymph or chyle,
the receptaculum chyli, and extends up along the spi-
nal column for a distance of about eighteen inches to the
seventh cervical vertebra, where, with the right lym-
phatic duct, it empties into the left subclavian vein at its
junction with the internal jugular, thus establishing direct
communication between the lymph spaces and the ve-
nous system. The orifices of both vessels are guarded
by semi-lunar valves to prevent regurgitation of the
blood.

The lymphatic glands are small oval glandular bodies
and occur here and there along the course of the lymph-

skin reflected.
Pectoralis major.
Central group of glands

Cephalic vein.

Basilic vein.
Intercostohumeral nerve.

Auxiliary fascia.
Long thoracic vein.

FIG. 9.— Central (superficial) lymphatic glands of the axilla. (After Leaf.)

atics. Before entering one of them the vessel breaks
up into several afferent vessels which form a plexus
within and then emerge again as several efferent vessels
which soon unite to form one trunk. These glands oc-
cur chiefly in the mesentery, along the great vessels,
and in the mediastinum, axilla, neck, elbow, groin, and
popliteal space.

The lymph varies in character with the locality, being
a little thicker and more opalescent in the lacteals, as
the lymphatics of the small intestine are called, especi-

GENERAL STRUCTURE OF THE BODY. 33

ally during digestion, when fat is present. Here it is
called chyle. Otherwise it is generally a clear, trans-
parent and slightly opalescent fluid, which, owing to
the presence of fibrin, clots when drawn from the body
and allowed to stand. In fact, it resembles blood
plasma very closely in composition and, as it also con-
tains a certain number of corpuscles or leucocytes that
just correspond to the white corpuscles of the blood,
it is practically blood without the red corpuscles.
These leucocytes have considerable power of amoeboid
movement and are thought by some to play an im-
portant part in the absorption of food.

Owing to intracapillary pressure, the lymph trans-
udes into the lymph spaces and bathes the tissues, being
carried away again by the lymphatics. The amount of
transudation is determined by the blood pressure — the
greater the pressure, the greater the amount of trans-
udation— and is increased by some organic action of the
cells in the walls of the vessels. In the process of transu-
dation a certain amount of solid matter goes through the
wall of the vessel and it is probable that certain protein
elements can be carried thus from the blood-vessels to
the lymphatics, though they do not pass through the
capillary wall as readily as other substances. Some
lymph is also probably formed by the action of the tis-
sues themselves, though the process is not understood.

All muscular movements, active or passive, includ-
ing the respiratory movements, tend to drive the lymph
on its way by pressure, the valves of the vessels keep-
ing it from flowing back. Moreover, its flow is from the
capillaries to the veins or from a region of high pressure
to one of less pressure. There is probably also some con-
traction in the walls of the vessels themselves, and the
continual formation of lymph helps to drive it along. If
an obstruction to the circulation occurs, however, back-
pressure results and causes too great transudation. In
that event a limb becomes swollen, pale, and generally
cool. It pits on pressure, the pressure driving the lymph

34 GENERAL STRUCTURE OF THE BODY.

out and there being no circulation to bring it back.
This condition is called oedema and occurs in liver,
kidney, and heart troubles, being generally first ob-
served at the ankles. In ascites, hydrothorax, hydro-
cephalus, and pericardial and pleural effusions the fluid
corresponds to lymph in its composition and the large
amount is due to excessive formation of the fluid, which
is normally present in small quantities.

Lymph gives the tissues substances from the blood
that they need and carries off those they do not, whether
waste or substances of use to other tissues. Because
they thus absorb certain materials not needed by the
tissues and convey them to the circulation, the lymph-
atics have also been called absorbents. Indeed, lymph
may be spoken of as the middleman between the blood
and the tissues.

Another function of the lymph is to lubricate. Thus,
the synovial fluid of the joints is lymph and the pleurae
and the pericardium contain lymph or serum to reduce
the friction between the adjoining surfaces as much as
possible. The brain and spinal cord do not quite fill
the cavities of the cranium and the spinal column but
float on a cushion of lymph, the cerebro-spinal fluid.
When the brain, which is subject to increase and dimi-
nution in size, increases in size, it drives the lymph out,
and when it diminishes, the lymph returns.

The lymph glands serve as a protection to adjacent
parts and when it leaves the gland the lymph is purer
and richer in leucocytes than when it entered. In fact,
they filter harmful matter from the lymph and appar-
ently also form white corpuscles. Normally they can
with difficulty be felt, but in disease, if the leucocytes
are unable to destroy or carry off the poison, the lymph
carries it along to the glands, which swell and become
tender. If the infection is not severe the swelling goes
down and the tenderness passes after a short time, but
if it is severe, there may be suppuration and abscess for-
mation and the gland even perhaps be' destroyed, giving

GENERAL STRUCTURE OF THE BODY. 35

its life for the health of the part. Thus a wound in the
foot, if infected, may cause irritation and enlargement
of the glands at the knee and in the groin.

The lymphatic glands are frequently the seat of tu-
bercular infection, especially in the neck, and are en-
larged in scarlet fever, tonsillitis, and diphtheria. In
syphilis there is general glandular enlargement, and the
glands in the groin become enlarged in all diseases of
the genital organs. In malignant growths, such as can-
cer, the extension of the disease is often along the lines
of the lymphatics.

Glands. — Of glands in general a word might now be
spoken. They are of two kinds, excreting and secret-
ing, and, when simple, are formed by the folding in of
a free surface, as in the case of the salivary, gastric, and
sebaceous glands, the cells at the gland becoming so
modified as to be able to perform the function of excret-
ing or secreting. In racemose glands the gland is
broken up into many pockets. Excreting glands take
from an organ or from a part substances which have out-
lived their usefulness and are to be cast out of the body,
while the secreting glands form from the blood sub-
stances that did not exist in it before, but which are of
use to the body, as the ptyalin of the saliva. A strict
line cannot, however, be drawn between the two kinds
of glands, most glands partaking more or less of both
functions, though the sebaceous and sweat glands are
probably purely excreting glands and the salivary glands
are almost purely secreting. The glands, moreover,
are more or less interchangeable in their functions, that
is, they have vicarious function, and one gland can take
up and do for another what that other is for some reason
unable to do. In jaundice, where there is stoppage of
the bile duct, the kidneys help out the liver by excret-
ing the bile. If one kidney is removed the other does
work for both, and the glands of the skin may help out
the kidneys or vice versa. Hemorrhage from the lungs
sometimes occurs in suppression of the menses.

36 GENERAL STRUCTURE OF THE BODY.

In a general way the function of glands is chemical.
They filter out by osmosis, selecting the useful parts
for secretion and the useless for excretion. In the chem-
ical action that goes on considerable energy is given off,
as is shown by the amount of pressure in the glands and
by the fact that their temperature is higher than that
of the blood. They all work in a reflex manner, being
under the control of the central nervous system. Thus,
what is eaten affects the nerve terminals in the mouth,
the sensation passes to the nervous system, and an im-
pulse is carried by the motor nerves to the salivary
glands.

Most of the glands have ducts to convey away their
secretion to other parts of the body or to send excretions
out of the body, but there are also ductless glands, which,
though they seem to have some important function in the
process of metabolism, are not well understood. Most of
them seem to manufacture some substance that is
absorbed by the tissues and that plays an important
part in the bodily metabolism, though nothing is se-
creted by them externally. They are said to have an
internal secretion, whereas the glands with ducts have
an external secretion. The liver has both forms of se-
cretion, the bile which is sent out and the glycogen that
is stored. The ductless glands are the thymus and thy-
roid glands, the suprarenal capsules, and the pituitary
body in the brain.

Nervous Tissue. — Presiding over all the organs, mus-
cles, and blood-vessels, as the source of all action and
all sensation, are the nerves. Nervous tissue is of two
kinds: 1. the gray or vesicular, which originates im-
pulses and receives impressions, and 2. the white or fi-
brous, which conveys impressions. The gray matter
consists of large granular cells of protoplasm containing
nuclei, which give off many branches or dendrites.
From the under surface there usually comes one main
branch, the axis-cylinder process. These processes
sometimes give off branches and sometimes not, but

GENERAL STRUCTURE OF THE BODY.

they form the nerve fibers and carry impulses away from
the nerve cells. The cells of the processes are elongated
in shape, have a nucleus, and are placed end to end, with
a definite constriction between them.

Each axis-cylinder process is surrounded by a sheath
called the medullary sheath, while each
nerve fiber consists of a central axis-cylin-
der process surrounded by the white sub-
stance of Schwann and enclosed in a
sheath. A bundle of these fibers invested
in a fibro-areolar membrane called the
neurilemma constitutes a nerve, and of
these the white matter is formed. The
blood supply is brought by minute vessels,
the vasa nervorum.

The nerves of the cerebro-spinal system
preside over animal life and have to do
with voluntary acts, while those from the
sympathetic system regulate organic life
and are quite independent of the will.
Both sensory and motor nerves extend all
over the body, accompanying the arteries
in a general way. The sensory nerves
end on the surface in plexuses, in end
bulbs situated in the papillae of the skin,
or in tactile corpuscles, these last occur-
ring more especially where there is no medullary sheath

,° c, neurilemma; a,

hair. The motor nerves end peripherally nucleus; e, node of

! i i i , mi 1 Ranvier. (Leroy.)

in plexuses or by end plates. The central
terminations of the motor nerves and the terminations
of sensory nerves in special organs, except where they
end in a cell, are not well understood.

Like muscles, nerves are probably never at rest, for
through them the muscles get their tone. When a nerve
acts, no heat is produced and there is no change in the
nerve afterward, as there is in muscle. Probably nerve
impulse is the transmission of physical rather than chem-
ical changes along the fiber, the atoms of the nerve being

38 GENERAL STRUCTURE OF THE BODY.

set in vibration and the vibrations being transmitted
along its length. Stimulation is produced by physical
injury, by chemical influence, by electricity, by heat,
and the message is always referred to the nerve termi-
nation. Thus, if the nerve at the elbow, over the
"crazy bone," is touched, a tingling is felt in the fingers
rather than at the point of pressure. A person who has
had an arm or leg amputated will frequently speak of
his fingers or toes on that side being cold, or complain
of pain in them, because the scar below the point of am-
putation tightens around the nerves and pinches them.
It is through the nerves that people get in touch with
the outer world and that they judge of size, weight, etc.
All careful adjustment of the muscles is under the
control of the nervous system.

CHAPTER II.
THE SKIN, ITS APPENDAGES AND ITS FUNCTION.

The whole exterior surface of the body is covered by
the skin, an excreting and absorbing organ, which serves
as a protection to the parts beneath and is also the or-
gan of touch. It has two layers, a superficial and a

Hair.

Hair follicle.
Sweat gland.

FIG. 11. — Vertical section of skin.

deep. The superficial layer, the epidermis or cuticle,
is composed wholly of epithelial cells, of which the deep-
est layer is columnar and moulded upon the papillary
layer of the derma, while the intermediate layers
are more rounded and the surface ones flat. The
deepest layer also contains the skin pigment, which
causes the variation in shade between the Indian, the
negro, and the white man. Below the epidermis, which
is chiefly protective, is the tough, elastic, and flexible
tissue of the derma or true skin, in which are vested
most of the activities of the skin. Its surface is covered
with papillae, which are more numerous in the more
sensitive parts. Each papilla contains one or more
capillary loops and one or more nerve fibers, while some
terminate in an oval body known as a tactile cor-
puscle. Beneath the papillae is the reticular layer, com-
posed of interlacing bands of fibrous tissue and contain-

40 THE SKIN, ITS APPENDAGES AND ITS FUNCTION.

ing blood-vessels, lymphatics, and nerves, as well as un-
striped muscle fibers where hair is present.

At the apertures .of the body the skin stops and is
replaced by mucoiis membrane, an integument of greater
delicacy but which consists fundamentally of the same
two layers, a superficial, bloodless epithelium and a
deep fibrous derma. It is continuous with the skin,
but is much redder and more sensitive and bleeds
more easily. The passages and cavities that it lines,
unlike those lined by serous membranes, communicate
with the exterior of the body and are for that reason
protected against contact with foreign substances by
mucus, which is thicker and more sticky than the
lymph that moistens the endothelium found on serous
surfaces. Mucous membrane is found in the alimentary
canal, the respiratory tract, and the genito-urinary tract.
In cavities, like the stomach and intestines, which are
subject to variations in capacity, it is thrown into folds
or rugae. The mucus is secreted by small glands in the
membrane.

Appendages of the Skin. — The skin has various ap-
pendages. On the dorsal surface of the last phalanges
of the fingers and toes are flattened and horny modi-
fications of epithelium, the nails. They have a root
embedded in a groove of skin by which they grow in
length and a vascular matrix of derma beneath them
which gives growth in thickness. To their growth
in length there seems to be no limit.

The hairs also, which occur all over the body, ex-
cept on the palms of the hands and the soles of the
feet, are a modification of the epithelium. Each hair
has a bulbous root springing from an involution in the
epidermis and derma called the hair follicle, into which
one or two sebaceous glands empty. It is raised by
involuntary muscle fibers and grows by constant ad-
ditions to the surface by which it is attached. This
growth seems, however, to be limited, and when its
term is reached the hair falls out and is replaced by

THE SKIN, ITS APPENDAGES AND ITS FUNCTION. 41

another. The horny epithelial cells that go to form
the hair contain the pigment that gives it its color.
Like the hairs, the sebaceous glands are situated in all
parts of the body except the palms of the hands and the
soles of the feet. They lie in the papillary layer and

FIG. 12. — Skin and longitudinal section of hair: a, Epidermis; b, corium; c,
sebaceous gland; d, fibrous root-sheath; e, glassy membrane;/, outer root-sheath;
g, inner root-sheath; h, expanded bulbous end of hair; i, papilla of hair; ;',
arrector pili; k, adipose tissue. (Leroy)

empty into the hair follicles, except occasionally, when
they empty directly upon the surface of the skin. They
secrete an oily substance, sebum, the debris resulting
from the degeneration of the epithelial cells of the
gland itself, which serves to keep the hair glossy and
the skin soft and flexible.

42 THE SKIN, ITS APPENDAGES AND ITS FUNCTION.

The sweat glands, on the other hand, are more fre-
quent on the palms and soles and though sometimes
found in the derma are usually situated lower down in
the subcutaneous cellular tissue. They are least nu-
merous on the back and neck. Coiled up in the lower
layers of the skin, they discharge the sweat through a
spiral excretory duct upon its free surface.

The sweat is a clear, colorless, watery fluid with a
salty taste, an alkaline reaction, and a characteristic
odor that varies with the individual. If very scanty,
it may be acid in reaction. Besides water it contains
a small percentage of solids, as inorganic salts, especi-
ally sodium choloride, fatty acids, neutral fats, and
at times, especially in some diseases of the kidneys,
urea, that is, the end-products of the metabolism of
starches and fats chiefly. There is usually also some
carbon dioxide, whence the expression cutaneous respi-
ration.

The sweat serves to keep the skin moist and in good
condition, to remove outworn and poisonous or ir-
ritating matters, and to regulate the temperature. As
a rule it evaporates upon reaching the surface, in which
case it is known as invisible or insensible perspiration,
but if conditions of the atmosphere are not favorable
to prompt evaporation, as when the air is damp, the
skin becomes damp and there is visible perspiration.

Though an abundant supply of blood increases the
action of the sweat glands, they are regulated by defi-
nite secretory nerves rather than by the vasomotor
nerves. In a cold sweat the action is probably due
to some disturbance of the nerve supply without in-
crease of the blood supply. Ordinarily perspiring is
a reflex act due to the stimulation of the afferent cu-
taneous nerves, as by the application of heat, but some-
times, as in cases of strong emotions, involuntary im-
pulses are sent from the brain to the spinal centers and
so arouse the action of the glands. Atropin has the
power of preventing the secretion of sweat by paralyz-

THE SKIN, ITS APPENDAGES AND ITS FUNCTION. 43

ing the terminations of the secretory nerves, while
pilocarpin produces an opposite effect in a similar way.

On account of these sweat glands the skin becomes
next in importance after the kidneys in the excretion
of waste products. The quantity of sweat excreted
varies greatly and is hard to measure. It is influ-
enced by the temperature and humidity of the sur-
rounding air, by the nature and quantity of food and
drink consumed, by the amount of exercise, the rela-
tive activity of other organs, especially the kidneys,
and by certain mental conditions. The hotter it is,
the greater the amount of perspiration. In damp
weather there may be less perspiration, but it does not
evaporate and is therefore more in evidence.

Ordinarily man has a temperature of 98.6°. The
source of this body heat or temperature is the general
body metabolism, muscular activity, and activity of
the glands, especially of the liver, which is constantly
active, the blood in the hepatic vein being warmer than
that in any other part of the body. The tissue of the
brain also is said to be warmer than the surrounding
blood, and the heart and respiratory muscles, which
are in constant activity, are responsible for much of
the body heat. The amount of heat generated in the
body, therefore, varies at different times, according as
a person is awake or asleep, quiet or active.

Temperature Regulation. — The temperature is reg-
ulated by variations in the production and loss of heat,
less being known of its production than of its loss. It
has been calculated that four-fifths of the energy of
the body is converted into heat, one-fifth into work.
As the minimum amount of heat produced in twenty-
four hours is sufficient to raise 10 gallons of water from
0° to boiling-point, it is evident that if there were not
some way for the escape of much of this heat the body
would become hotter and hotter and finally destroy itself.
The temperature, however, except on the surface, is
uniform, heat being lost as fast as it is produced. For,

although oxidation at any point raises the heat of the
blood at the point, this heat is carried by the blood to
other parts, to which the surplus is given up, while blood
cooled in the skin goes to the hotter inward parts to cool
them and be warmed itself. In fact, heat is expended by
conduction and radiation, through respiration, perspira-
tion, and heat given to the urine and faeces. It is,
therefore, largely, 75 to 80 per cent., carried off through
the skin and the lungs; 60 to 70 per cent, is lost by
radiation to the air and other bodies with which the body
comes in contact; 20 to 30 per cent, is lost by the evap-
oration of sweat, 4 to 8 per cent, by the warming of ex-
pired air, urine and feces, and 1 to 2 per cent, by cold
food that is taken in. Radiation acts more favorably
where the surroundings are cool and the air in motion,
as on a breezy day. Conduction is carried on best where
the surrounding air is cool, especially if it is moist, for
moist air is a better conductor of heat than dry air.
Evaporation is very important in hot weather or where
men work in hot air.

Even in health the temperature may range from 98.6°
to 99.5°, and a degree or two below or above is not danger-
ous. When a person first gets up in the morning his
temperature is apt to be subnormal, but after food and
exercise have been taken it becomes normal and stays so
till the end of the day, when, if the person is tired, it may
go up a little. If a person is tired out, the temperature
is apt to be subnormal. There is also in the body what
is called the vital tide, which is highest afternoon and
evening and lowest in the morning.

The rate of production of heat varies greatly in differ-
ent people. One person uses a certain amount of tissue
more quickly than another, that is, he lives faster. More-
over, size makes a difference in that a small body has
more surface to its weight than a large one and so has
to produce the same amount of heat at a faster rate in
order to maintain the right temperature. Taking food
increases heat, probably because of the muscular effort

THE SKIN, ITS APPENDAGES AND ITS FUNCTION. 45

needed to eat it. Muscular work is another factor. And
finally the whole matter of heat production seems to be
under the control of the nervous system. Not much is
known on this point except that there is a heat center in
the medulla which plays an important part in heat pro-
duction and whose influence is seen where the tempera-
ture shoots way up in disease just before death. It is
now thought that fever is due to a disturbance of this
nervous mechanism, though just what the disturbance
is is not known.

Fever is a condition of increased bodily temperature,
due to increased production or to decreased loss of heat.
As a rule, in all fevers the metabolic changes in the body
are increased. Hence the patient becomes emaciated
in a long fever. The frequent increase in the amount of
urea during fever shows an increase in protein metabo-
lism. The temperature in fevers rises as high as 106°
and in sunstroke sometimes to 110°. Except in sun-
stroke a higher temperature than 106° generally means
death. Subnormal temperature is due to a decrease in
the bodily metabolism and so to lessened heat production.
As a rule, if the functions are all active, especially that of
the sweat glands, a person can be exposed to severe heat
without the temperature being affected, though some-
times on a hot summer day it may be up half to one
degree. The cause of heat-stroke with its high fever is
unknown, but probably it is due to some effect on the
heat center in the brain. Heat prostration is also due
to prolonged exposure to heat, but is generally accom-
panied by a subnormal temperature. The effect of cold,
as in freezing, is to diminish all the metabolic activities
of the body. The temperature can be artificially regu-
lated more or less by variations of food, varying amounts
of exercise, by drugs, etc.

Sense of Touch. — Before passing on to a discussion of
the individual parts, a few words might well be said of the
sense of touch, since that is general and resides largely
in the skin, whose other functions have just been de-

scribed. It may be regarded as the form from which all
the other special senses have developed, certain portions
of the body having become more sensitive than others
to certain vibrations, as the eye to those of light. The
internal organs probably have little sense of touch.

Touch is useful only within arm's reach but there
gives one a sense of space that sight does not give. It is
practically determined by the touch corpuscles, which are
found in the skin over almost the entire body, though

.»v« :•*_-«_-. .1 Nerve fiber.

— j- — Nerve fiber.

Capsule.

\«KV

„_ Nerve fiber.

Nerve fiber.

FIGS. 13, 14. — Meissner's corpuscle from man; X750. (Bohm, Davidoff, and
Huber.)

they are more numerous in some places than in others,
the distribution of the corpuscles determining the
sensitiveness of the skin. These touch corpuscles are
protoplasmic bodies containing nuclei, about which are
entwined filaments from the cutaneous nerves. Where
the corpuscles are absent the filaments of the cutaneous
nerves themselves play an important part. The finger
tips have a very delicate sense of touch and the tip of the
tongue is the most sensitive part of the body. Hence
spaces in the mouth seem larger than elsewhere. By the

transmission of sensations of touch to the brain the sen-
sation is localized and the tactile sensation becomes a
tactile perception.

There are three main divisions of the sense of touch: 1.
sensations of touch proper or tactile sensation; 2. sen-
sations of temperature, and 3. sensations of pain. The
temperature sense is the transmission by the skin of sen-
sations not so much of a certain degree of heat or cold as
of the difference between the temperature of an object
and that of the skin. The longer an object is in contact
with the skin, the less conscious the person is of it, not
only because it becomes of the same temperature, but
also because he becomes accustomed to it. There also
seem to be in the skin, besides the touch corpuscles, two
other terminal organs with separate nerve fibers, the one
for detecting heat, the other cold; for there are places on
the body where heat can be detected and cold cannot,
and vice versa.

Sensations of pain may be merely an exaggeration of
tactile sensation, as in too hard pressure or too great heat,
but there seems to be also a sensation of pain in the skin.
All organs are said to have common sensibility to pain
and any exaggeration of this sensibility causes a sensa-
tion of pain. All the special senses require a certain
amount of judgment in the interpretation of the sensa-
tions they convey.

CHAPTER III.
THE CRANIUM AND FACE.

The intelligence and all the special senses, except the
sense of touch already spoken of, are gathered together
compactly in the head, where they are carefully protected
with bony tissue. Covering the brain is the skull or cra-
nium, which is made up of eight bones, the frontal, the
occipital, two parietal, two temporal, the sphenoid, and
the ethmoid, while the bones of the face are fourteen in
number, two nasal, two superior maxillary, two lachry-
mal, two malar, two palate, two inferior turbinated, the
vomer, and the inferior maxillary. For the most part
the bones are arranged in pairs, one on either side.

The Cranial Bones. — The cranium or skull is especially
adapted for the protection of the brain and the bones are
flat and closely fitted to its surface. They have two
layers of bone, the outer and the inner tables, of which
the outer is the thicker, and between these is a tissue
filled with blood-vessels, the diploe. In the infant, whose
brain has not yet attained its full size, opportunity must
be left for growth and the skull therefore consists of a
number of bones with interlocking notched edges, where
growth takes place, but in the adult it forms one solid
covering of bone.

The line where the edges of two cranial bones come
together is called a suture. The suture between the
frontal bone and the forward edges of the two parietal
bones is called the coronal suture, that between the two
parietal bones at the vertex of the skull is known as the
longitudinal or sagittal suture, and that between the
occipital bone and the back edges of the parietal bones
as the lambdoidal suture.

THE CRANIUM AND FACE. 49

Where the coronal and sagittal sutures meet is a
membranous interval known as the anterior fontanelle,
while the posterior jontanelle is at the juncture of the
sagittal with the lambdoidal suture. These fontanelles
— so called from the pulsations of the brain that can be
seen in them — close after birth either by the extension of
the surrounding bones or by the development in them
of small bones known as Wormian bones , the posterior
one closing within a few months, the anterior by the end

FIG. 15. — Cranium at birth, showing sutures and fontanelles.

of the second year. In rickets, however, the anterior
fontanelle remains open a long time, sometimes into the
fourth year.

The frontal bone, as its name implies, forms the fore
part of the head or forehead. It joins the parietal bones
above and the temporal bones on either side. At the
lower edge are the supra-orbital arches, each with a
supra-orbital notch or foramen on its inner margin for
the passage of the supra-orbital vessels and nerve, the
nerve most affected in neuralgia. Just above the
arches on either side are the superciliary ridges, behind
which, between the two tables of the skull, lie the frontal
sinuses. On the inner surface the frontal sulcus for the
longitudinal sinus runs along the median line.

The parietal bones are the side bones of the skull.
They meet each other in the sagittal suture at the median

THE CRANIUM AND FACE.

line above and join the frontal and occipital bones at
either end, while below they touch upon the temporal
bones, the temporal muscles being attached in part along
their lower surface. These muscles are inserted into the
coronoid process of the lower jaw, which they thus help
to raise and to retract.

The occipital bone is at the base of the skull and at
birth consists of four pieces. In the lower, anterior part

FIG. 16. — Front view of the skull. (After Sobotta.)

is the foramen magnum, an oval opening through which
the spinal cord passes from the skull down into the spinal
canal. Half way between the foramen and the top of
the bone is the external occipital protuberance for the
attachment of the ligamentum nuchse which holds the
head erect. The inner side of the bone is deeply concave
and is divided by a cross-shaped grooved ridge into four
fossae, the internal occipital protuberance being situated

THE CRANIUM AND FACE. 51

where the arms of the cross meet. The occipital lobes
of the cerebrum lie in the two upper fossae and the hemi-
spheres of the cerebellum in the two lower ones. In the
grooves upon the ridge are the sinuses which collect the
blood from the brain.

The occipital and frontal muscles, united by a thin
aponeurosis, cover the whole upper cranium and are
known as the occipito-frontalis muscle. At the back this
is attached to the occipital bone, while in front it inter-
laces with various face muscles. It is a powerful muscle
and raises the brows, wrinkles the forehead, and draws
the scalp forward. Long hair grows on the skin over it
as a further protection against blows upon the skull and
sudden variations in temperature.

The temporal bones — said to be so named because the
hair over them is the first to turn with age — are situated
at the sides and base of the skull and are in three portions :
the squamous or scale-like, the mastoid or nipple-like,
and the petrous or stony portion. The squamous is
the upper portion and has projecting from its lower part
the long arched zygomatic process, which articulates
with the malar bone of the face and from which arises the
masseter muscle, one of the chief muscles of mastication,
' which has its insertion in the ramus and angle of the lower
jaw. Just above the zygomatic process the temporal
muscle has its origin in part, while below is the glenoid
fossa for articulation with the condyle of the lower jaw,
the posterior portion of the fossa being occupied by part
of the parotid gland.

The rough mastoid portion of the temporal bone is
toward the back and affords attachment to various mus-
cles, of which the most important are the occipito-
frontalis and the sterno-cleido-mastoid. Within it are
the mastoid cells, which communicate with the inner ear
and are lined with mucous membrane continuous with
that of the tympanum. They probably have something
to do with the hearing. In children they often become
the seat of inflammation (mastoid abscess) in infectious

52 THE CRANIUM AND FACE.

diseases and the mastoid bone has to be cut to let out pus
that has collected. As the lateral sinus is directly behind
the mastoid bone, there is very great danger of going
through into the sinus and causing a fatal hemorrhage.

The petrous portion, which contains the organ of hear-
ing, is between and somewhat behind the other two por-
tions, at the lower edge of the temporal bone, wedged
between the sphenoid and the occipital bones. On its
outer surface is the external auditory meatus, and from

Vlrtlf

FIG. 17.— Side view of the skull. (After Sobotta.)

below projects a long sharp spine called the styloid pro-
cess, to which several minor muscles are attached. In
the same angle between the petrous and squamous por-
tions lies the bony Eustachian tube.

The sphenoid or wedge bone, so called because in the
process of development it serves as a wedge, lies at the
base of the cranium, forming as it were the anterior part
of the floor of the cavity containing the brain. It is a

THE CEANIUM AND FACE. 53

large, bat-shaped bone and articulates with all the cranial
and many of the facial bones, binding them all together.
It has a body, two large wings, and two lesser wings and,
appears on the outside of the skull between the frontal
and the temporal bones behind the zygomatic process.
In the adult the body of the sphenoid is hollowed out into
the sphenoid sinuses, in which pus sometimes forms.

The Ethmoid Bone. — In front of and below the sphe-
noid and extending forward to the frontal bone is the
ethmoid, the last of the cranial bones. It consists of a
horizontal cribriform or sieve-like plate, from either side
of which depend lateral masses of ethmoid cells. To
the inner side of these masses are attached the thin
curved turbinated bones, superior and middle, while be-
tween them is a vertical plate that forms the bony sep-
tum of the nose. • Rising from the upper surface of the
cribriform plate is another vertical plate, the crista galli,
with the olfactory grooves on either side for the reception
of the olfactory bulbs, filaments of the olfactory nerve
passing down through the perforations of the cribriform
plate to the nose. For the brain, which fills almost the
entire cavity of the cranium, is supported by the sphenoid
and ethmoid bones internally, as it is protected externally
by the other cranial bones.

Ossification of Sutures. — If premature ossification of
all the sutures occurs, idiocy results, while in cephalocele
there is a gap in the ossifying of the bones so that the
membranes or brain protrude. In rickets the forehead
is high and square and the face bones poorly developed,
so that the head looks larger than it really is. In Paget's
disease the bones enlarge and soften. This affects the
head but not the face and often the first thing noticed is
that the hat is too small. Craniotabes is thinning of the
bone in places, the bone becoming like parchment and
being easily bent. It is generally caused by pressure of
the pillow or the nurse's arm.

Bones of the Face. — The facial bones serve to form the
various features of the face, which after all are merely

54 THE CRANIUM AND FACE.

organs of special sense. Many delicate muscles control
the facial expression which, consciously or unconsciously.
reflects the character of their owner.

Surgically the most important of the facial bones are
the two superior maxillary bones, because of the number
of diseases to which they are liable. They meet in front ,
together forming the upper jaw, and with the malar bone
help form the lower part of the orbit of the eye. They
are cuboid in shape and are hollowed out into a pyramidal
cavity called the antrum of Highmorc, which opens by a
small orifice into the middle nasal meat us and which
sometimes becomes infected and has to be tapped. The
nasal process for articulation with the frontal and nasal
bones has, at its lower edge, a crest for the inferior turbin-
ated bone, and close beside this on the inside, extending
down from the upper edge, is a deep groove which, with
the lachrymal and inferior turbinated bones, help-
form the lachrymal canal for the nasal tear duct. The
bones give attachment to many small muscles, connected
for the most part with the nose and mouth, of which the
masseter is the only important one.

The two malar or check bones are small quadrangular
bones, which form the prominences of the cheeks and
help form the orbits of the eyes. Projecting backward
from each is a zygomatic process for articulation with the
zygomatic process of the temporal bone, while a maxil-
lary process extends downward for articulation with the
superior maxillary. Here again the most important
muscle attached is the masseter. If the malar boi;
crushed great deformity results.

The lachrymal bones are two small bones, about the size
and shape of a finger-nail, situated at the front of the
inner wall of the orbit. At the external edge is a groove
which lodges the lachrymal sac above and forms part of
the lachrymal canal below.

The two palate bones are at the back of the nasal
and help to form the floor of the nose, the roof of the
mouth, and the orbit. Each has a vertical and a hori-

THE CRANIUM AND FACE. 55

zontal plate, and it is these last that by their juncture
form the hard palate. Oftentimes in cases of hare-lip
clejt palate also occurs, the result of incomplete develop-
ment. To remedy the consequent opening in the roof
of the mouth, which makes articulation difficult, opera-
tion is generally resorted to, though sometimes a plate
is fitted over the opening by a dentist.

The nasal bones are two small oblong bones which
articulate with the frontal and superior maxillary bones
and with each other. They form the bridge of the nose,
the rest of the nose being wholly of cartilage, except
for the vomer, a bone shaped like a plough-share, which
forms part of the nasal septum, articulating along its
anterior edge with the ethmoid and the triangular
cartilage.

The two inferior turbinated bones lie along the outer
walls of the nasal fossa?. They are thin scroll-like bones
covered with mucous membrane and serve to heat the
air as it passes in. Sometimes when one has a cold, the
membrane and the bone too swell up and close the nares.
Loss of the sense of smell in a bad cold may be due to
such swelling and the consequent impeding of the en-
trance of odoriferous particles — a condition that would
likewise interfere with the sense of taste. Part of the
bone is sometimes removed, to enlarge the passage,
enough being left to warm the air.

Lastly, there is the inferior maxillary bone or lower jaw.
This has a horseshoe-shaped body and two rami, one at
either end. Each ramus has a pointed process in front
called the coronoid process, into which is inserted the
temporal muscle. At the back, and separated from the
coronoid process by the sigmoid notch, is the condyle,
which articulates with the glenoid fossa on the temporal
bone. The rami also give attachment to the masseter
muscle at its point of insertion. In adult age the ramus
is almost vertical but in old age the portion of the jaw
hollowed out into alveoli for the teeth becomes absorbed
and the angle of the jaw becomes very obtuse. On the

56 THE CRANIUM AND FACE.

inner side of the jaw near the middle on either side is the
fossa for the sublingual gland, while the submaxillary
gland lies in a fossa farther back on either side.

Sometimes the lower jaw is dislocated and when once
this has occurred it is liable to occur again, the ligaments
becoming stretched.

CHAPTER IV.
THE ORGANS OF SPECIAL SENSE.

The Nose. — The nose, the organ of the sense of smell,
is composed of a framework of bones and cartilages, the
bridge being formed by the two nasal bones, and the
septum by the vomer and the triangular cartilage. It
consists of two parts, the external nose and the internal
or nasal fossce, which open to the face by the anterior
nares or nostrils and into the pharynx by the posterior
nares. Externally it is covered with skin, internally
with ciliated mucous membrane. The jossce have the

FIG. 18.— The nasal cavity. (After Sobotta.)

inferior turbinated bones along their outer walls and are
divided into three parts known as the superior, the
middle, and the inferior meatus, the middle one connect-
ing with the antrum of Highmore, while into the inferior
meatus the lachrymal canal empties. There are many
small muscles of which little use is made, although in

58 THE ORGANS OF SPECIAL SENSE.

forced respiration, as in pneumonia, where every aid to
breathing is called into play, even the alse nasi or nos-
trils are made to exert what muscular power they pos-
sess in order to supply more air.

Not only is most of the air breathed in through the nose
and warmed in its passage through, but the nose is the
organ of smell and by means of the peculiar property of
its nerves protects the lungs against deleterious gases and
helps the taste discriminate. The olfactory or first cranial
nerves, after emerging from the brain, lie on the under sur-
face of the frontal lobe and rest on the ethmoid bone in
what is known as the olfactory tract. Each nerve ends
in a bulb-like termination called an ol/actory bulb, which
rests on the cribriform plate and sends little terminal
fibers down through to be distributed to the nasal cavities,
especially to the upper half of the septum of the nose, the
roof of the nose, and the anterior and middle turbinated
bones. For in the mucous membrane of the upper nasal
cavity are specially modified epithelial cells called
olfactory cells, which play an important part in the con-
duction of smell. Hence when one wishes to smell any-
thing especially well he sniffs it up.

Probably the sensation of smell is caused by odorifer-
ous particles in the atmosphere being breathed into the
nose, where they affect the olfactory cells, which transmit
the impulses to the olfactory nerve and so to the brain.
Whereas a certain amount of moisture in the nasal cavity
seems to be essential for accuracy of smell, the presence of
too much or too little interferes with it. The mucous
membrane has a certain power also of distinguishing
different smells at the same time, though this power
varies greatly in different people, one smell often wholly
overpowering all others.

The cartilage below the bridge of the nose is sometimes
attacked in syphilis and cancer, and lupus often begins
on the nose. Deviation of the septum may occlude all air
from one side of the nose, an effect also produced by
polypi, generally of the turbinated bone. Either condi-

THE ORGANS OF SPECIAL SENSE. 59

tion is easily remedied. Nosebleed, though generally un-
important, may be serious in adults.

The Mouth. — The mouth is of great importance as an
entrance for fresh air to the lungs when the nasal passages
are for any reason impeded and as the resonant chamber
from which proceeds the voice, man's chief means of
communication with his fellows. Its chief value may be
said, however, to reside in the fact that it is the vestibule
of the alimentary canal. It is an ovoid cavity lined with
mucous membrane and is bounded in front by the lips,
at the sides by the cheeks, below by the floor and tongue,

FIG. 19.— The hyoid bone. (Toldt.)

and above by the hard palate anteriorly and by the soft
palate posteriorly, the uvula depending from the latter
like a curtain between the mouth and the pharynx.
Shape is given to the mouth by the bones of the upper
and lower jaw and its -size is altered by the lowering and
raising of the latter, which is quite freely movable.

At the back of the mouth, at the entrance to the phar-
ynx, are the anterior and posterior pillars of the fauces,
which contain muscular tissue, and between which on
either side are thick masses of lymphoid tissue, the tonsils.
The floor of the mouth is formed largely by the tongue,
which completely fills the space within the lower teeth.

60 THE ORGANS OF SPECIAL SENSE.

Its base or root is directed backward and downward and
is attached by muscles to the hyoid bone and the lower
jaw, the hyoid bone being a horseshoe-shaped bone lying
just below and as it were within the inferior maxillary.
The base of the tongue is attached also to the epiglottis
and at the sides to the soft palate by the anterior pillars.
Except at its base and the posterior part of its under
surface the tongue is free, but a fold of mucous membrane,
thefrenum, holds it somewhat in front. Thus it possesses
great versatility of motion and serves as an auxiliary in
articulation, mastication, and deglutition.

The Teeth. — Securely embedded in either jaw are the
teeth, nature's instrument for the first preparation of the
food for digestion through tearing and grinding. The
incisors, which are in front, have wide sharp edges for
cutting the food. Next come the canine teeth with a
sharp point for tearing it, while at the back are the molars
with a broad flat top for grinding.

There are two sets of teeth: 1. the temporary or milk
teeth, twenty in number — four incisors, two canines, and
four molars in each jaw — which appear at from six
months to two years, and 2. the permanent teeth, thirty-
two in number — four incisors, two canines, known as eye
teeth in the upper jaw and as stomach teeth in the lower
jaw, four bicuspids, so-called because they have two
cusps where the molars have four or five, and six molars
in each jaw — which come from the sixth to the twenty-
first years. The first to appear are the two lower middle
incisors, which come at the age of six months. The last
to appear are the wisdom teeth, the farthest back of the
molars, which come at the age of twenty-one years or
thereabouts.

Each tooth consists of a crown or body above the
gum, a neck, and a fang or root within the gum. The
body is of dentine or ivory with a thin crust of enamel
and contains the pulp, a vascular connective tissue
containing many nerves. Beginning at the neck and
covering the fang is a layer of cement or true bone.

THE ORGANS OF SPECIAL SENSE. 61

The Sense of Taste. — The sense of taste lies chiefly in
the taste buds as they are called which are filled with
gustatory cells and are found in the papillae of the tongue,
principally in the circumvallate papillce at the back of the
tongue, which are few in number and arranged in a V-
shape. There is also a certain power of taste in the tip
and sides of the tongue but little in the upper surface or
dorsum. Only five special tastes can be distinguished:
bitter, sweet, acid, sour, and salt, but sometimes more
than one can be distinguished at a time, as bitter and
sweet. Every one can distinguish between different
tastes but the power varies in different people and
with different conditions. Certain tastes seem to be
better distinguished in certain places, as sweet at the
tip and bitter at the back of the tongue. Moreover,
the sense of taste is very dependent upon the sense
of smell, especially in the case of aromatic and savory
substances, which one really does not taste but smell.
If one held his nose and closed his eyes he would not
know from the taste whether he was eating onion or
apple. This leads to the habit of pinching the nose
when taking nauseous medicines.

To be tasted a substance must be in solution. Friction
against the tongue, lips or cheek increase the sense of
taste. A temperature of 100° Fahrenheit favors taste,
while both great heat and great cold impair it.

There are probably at least two nerves of taste, the
lingual branch of the trifacial or fifth cranial and the
gustatory branch of the glosso-pharyngeal.

Along with the sense of taste there are other senses in
the mouth which play an important part, such as
pressure and the sense of heat and cold, and it is often hard
to distinguish them from the pure sensation of taste,
which indeed is always accompanied by them.

Salivary Glands. — On either side of the mouth are
three racemose glands for the secretion of the saliva,
which serves to soften and lubricate the food and parti-
ally to digest starches by means of its ferment, ptyalin.

62 THE ORGANS OF SPECIAL SENSE.

The parotid gland is the largest and is below and in front
of the ear, opening by Stensen's duct. The submaxillary
gland is below the jaw toward the back on either side
and its duct is Wharton's duct. The sublingual gland lies
beneath the mucous membrane of the floor of the mouth
and opens by eight to twenty tiny ducts beside the fre-
num, the ducts of Rivinus. The activity of the glands
depends upon the blood supply; the more blood the
greater their activity.

FIG. 20. — Dissection of the side of the face, showing the salivary glands: a,
Sublingual gland; b, submaxillary gland, with its duct opening on the floor of the
mouth beneath the tongue at d; c, parotid gland and its duct, which opens on the
inner side of the cheek. (After Yeo.)

The Tonsils. — The tonsils vary in size and in tonsillitis
swell and may even meet in the median line. They are
frequently removed. When they are enlarged one often
gets a third tonsil or adenoids, a lymphoid growth at the
back of the pharynx which causes mouth-breathing by
day and snoring by night. A child with adenoids is
starved for air and what air is breathed in is not warmed.
The growth should be removed.

A short frenum produces tongue-tie, which may be
remedied by snipping. Cancer of the tongue is fairly
common and necessitates a radical operation. In
mumps the parotid glands are inflamed and enlarged.

THE ORGANS OF SPECIAL SENSE. 63

The Ear. — The special organ of hearing is the ear, to
which there are three parts, the external, the middle,
and the internal ear.

The external ear consists of the pinna or expanded car-
tilaginous portion, for the concentration and direction
of sound waves, and the external auditory canal, partly
cartilage, partly bone, which is directed forward, inward,
and downward and conveys sound to the middle ear.

The middle ear or tympanum is an irregular cavity in
the petrous portion of the temporal bone. Its outer wall
is formed by the membrana tympani or drum, an oval
translucent membrane placed obliquely at the bottom of

l-Os articular*,
CrLra.,

FIG. 21. — The small bones of the ear; external view (enlarged). (After Gray.)

the external auditory canal. The middle ear communi-
cates with the inner ear through the fenestra ovalis or
oval window and contains the ossicles, the malleus or
hammer, the incus or anvil, and the stapes or stirrup,
which are arranged in a movable chain from the drum to
the oval window. The malleus, which is connected with
the membrana tympani, articulates by its head with the
body of the incus, while the stapes articulates with the
incus by its head and is connected by its base with the
margin of the oval window. Connection is made be-
tween the middle ear and the pharynx and the pressure
of the air upon the drum made equal on either side by
means of the Eustachian tubes. These tubes are about
an inch and a half long, have cilia, and convey wax and

64 THE ORGANS OF SPECIAL SENSE.

other matter from the ear to the pharynx. Occasionally
in a cold or for some other reason they become stopped
up and trouble results in the middle ear. Some of the
mastoid cells also connect with the middle ear and may
become infected, causing mastoid disease.

The internal ear consists of various chambers hollowed
out in the petrous portion of the temporal bone. There
is an osseous labyrinth, consisting of a central cavity
known as the vestibule, three semicircular canals, and the
cochlea, and within the osseous labyrinth, surrounded by

FIG. 22. — Interior view of left bony labyrinth after removal of the superior
and external walls: 1, 2, 3, the superior, posterior, and external or horizontal
semicircular canals; 4, fovea hemi-elliptica ; 5, fovea hemispherical 6, common
opening of the superior and posterior semicircular canals; 7, opening of the aque-
duct of the vestibule; 8, opening of the aqueduct of the cochlea; 9, the scala
vestibuli; 10, scala tympani; the lamina spiralis separating 9 and 10. (From
Quain, after Sommerring.)

perilymph, is the membranous labyrinth, of like form, filled
with the endolymph. Communication exists externally
with the middle ear by the round and oval windows and
internally with the internal auditory canal, through which
passes the eighth cranial or auditory nerve, the special
nerve of hearing, which is distributed to the inner ear
only. When the auditory nerve enters the ear through
this internal auditory meatus it divides into two branches,
of which one goes to the vestibule and the other to the

THE ORGANS OF SPECIAL SENSE. 65

organ of Corti, a group of specially modified epithelial
cells in the cochlea of the membranous labyrinth, which
is very important in transmitting the impulses to the
brain. The nerve also breaks up into very small
branches and is distributed practically throughout the
wall of the labyrinth.

The sensation of hearing is the result of impulses trans-
mitted to the auditory nerve and so conveyed to the
auditory center in the brain. It is caused by sound
waves which travel through the air from their point
of origin and enter the external ear. This collects and
selects the waves of sound and helps one to a certain
extent to determine the direction from which the sound
comes. As they pass through the external meatus the
sound waves are collected into a comparatively small
area for transmission to the middle ear, where, by means
of the drum, they set in vibration the chain of ossicles.
Through these the vibrations are in turn transmitted
to the oval window, being intensified in the process.
Here again they are taken up by the perilymph, from
which they pass through the wall of the membranous
labyrinth to the endolymph, affecting the epithelial
lining of the labyrinth in such a way that the impulses
are transmitted to the auditory nerve, more particu-
larly in the vestibule, from which the vibrations
enter the cochlea. They also affect the cells of the or-
gan of Corti in like manner as they pass from the peri-
lymph to the endolymph. The membrane that covers
the fenestra rotunda or round window relaxes and
expands as the vibrations strike it, thus serving to
eliminate the shock of impact.

Musical sounds are caused by rhythmical or regu-
larly repeated vibrations, while irregular vibrations
give rise to noises. In musical sounds loudness is deter-
mined by the height or amplitude of the vibrations,
pitch by the length of the wave, and quality by the
number of so-called partial tones. A sensation of sound
cannot be produced by less than 30 vibrations a second

66 THE ORGANS OF SPECIAL SENSE.

and the ordinary person cannot hear more than 16,000
vibrations a second. Different sounds can be distin-
guished when they follow each other as closely as by
one one-hundredth of a second.

All sound does not come through the canal of the
ear. The bones of the head vibrate and carry sound.
So there are instruments for the deaf which are put in
the ear and others which are placed between the teeth.

The semicircular canals are not essential to hearing
but have something to do with a person's power of
maintaining his equilibrium. Injury to them may
cause dizziness and loss of equilibrium.

The Eye. — One more feature, perhaps the most ex-
pressive, remains to be described, the eye. The senses
are all modifications of the original cutaneous sensi-
bility and the nerve of sight is no more sensitive to light
than any other nerve. It therefore needs an end
organ that is sensitive to the motions of the ether in
order to give impressions of light. This organ is pro-
vided in the eye, which is not only itself capable of be-
ing moved in every direction, but is placed in the most
movable part of the body, the head, which can be
turned in almost a complete circle. The eyeball is
spherical and lies in the cavity of the orbit upon a cush-
ion of fat, where it has a large range of sight but is
securely protected from injury by its bony surroundings.
The sunken eyes following protracted illness are due to
the using by the system of the fat on which the eye-
ball ordinarily rests.

Each orbital cavity is formed by the juncture of some
seven bones and communicates with the cavity of the
brain through the optic foramen and through the sphe-
noidal fissure. Above the orbits are arched eminences
of skin, the eye-brows, from which several rows of
short hairs grow longitudinally and which serve to pro-
tect the eyes and to limit the amount of light to a
certain extent, as in frowning.

Still further protection is afforded by the eyelids,

THE ORGANS OF SPECIAL SENSE.

longitudinal folds of skin, the one above, the other be-
low, which close like curtains over the eye. Beneath
the external layer of skin in the lids is fatty tissue and
then the orbicularis palpebrarum muscle by means of
which they are closed. They are kept in shape by the
tarsal plates or cartilages, in whose ocular surface are
embedded the Meibomian glands, whose secretion pre-
vents the free edges of the lids from sticking together.
Along these edges grows a double or triple row of stiff
hairs, the eye-lashes, which curve outward so as not to
interfere with each other and also to prevent the en-
trance into the eye of foreign bodies. Lining the
inner surface of the lids and reflected thence over

Levator of the upper eyelid

Superior rectus.
External rectus.
Inferior rectus.

Superior oblique.
Internal rectus.

Inferior oblique.

FIG. 23.— The external ocular muscles. (Pyle.)

the anterior surface of the sclerotic coat of the eye
is a mucous membrane, the conjunctiva, which is thick,
opaque, and vascular on the lids but thin and transpar-
ent on the eye-ball. The angles between the lids are
known as the internal a-nd the external canthus.

Muscles and Nerves. — The eyeball is held in posi-
tion by the ocular muscles, the conjunctiva, and the
lids, while surrounding it, yet allowing free movement,
is a thin membranous sac, the tunica vaginalis oculi.
The superior and inferior recti muscles at the upper
and lower edges of the ball turn the eye up and down;
the internal and external recti at the inner and outer

68 THE ORGANS OF SPECIAL SENSE.

edges turn the eye inward and outward; and the superior
and inferior oblique rotate the eye. The nerves supply-
ing these muscles are the third or motor oculi, the fourth
and the sixth.

The lachrymal gland, which is about the size and
shape of an almond, is situated at the upper and outer
part of the orbit. It secretes a fluid which keeps the
anterior surface of the eye bathed in moisture and is
ordinarily drained away through the lachrymal sac in
the inner canthus, whence it passes by the lachrymal
ducts into the nose. When the amount secreted is
excessive, it overflows the lower lid as tears.

Lacrimal gland.
Tarsal cartilage.

Nasal or tear-duct.

Canaliculus.
FIG. 24. — Diagram of the lacrimal apparatus. (Pyle.)

Coats of Eye. — The membranes or coats of the eye
are three in number: an outer or sclerotic, a middle or
vascular, and an inner or sensitive.

The sclerotic coat is a rather thick, fibrous, protect-
ive membrane. Where it passes in front of the iris,
however, it is thinner and transparent and is known
as the cornea. The cornea projects somewhat and, as
it were, resembles a segment of a smaller sphere set into
the rest of the sclerotic.

The middle or vascular coat, known as the choroid,
carries blood-vessels for the retina or sensitive coat in
its inner layer and has an outer layer of pigment cells
that excludes light and darkens the inner chamber of
the eye. The folds of the choroid at its anterior mar-

THE ORGANS OF SPECIAL SENSE.

gin contain the ciliary muscles and are known as the
ciliary processes, while the name iris is given to the little
round pigmented, perforated, curtain-like muscle just
in front of the crystalline lens. The posterior sur-
face of the iris is covered with a thick layer of pig-
ment cells to prevent the entrance of light except
through the central opening or pupil, and its anterior
surface also has pigment cells that give it its color,
though the difference in the color of people's eyes is due

Ocular muscle.

Retina.

Sclera.
Choroid.-

Ciliary muscle.
Iris.

Conjunc. cul-de-sac.

Ant. chamber and

aqueous humor.

Crystalline lens. /

Posterior chamber.

Angle of ant. chamber.

Suspensory ligament

of the lens.

Cornea. Vitreous chamber.

FIG. 25.— Vertical section through the eyeball and eyelids. (Pyle.)

rather to the amount of pigment present than to its
color, a small amount of pigment being present in blue
eyes and a large amount in brown and black eyes.
Variations in the size of the pupil are brought about by
contractions of the circular and radiating fibers of the
iris, contraction of the circular fibers making it smaller
and those of the radiating larger. The pupil is con-
stricted for near objects and during sleep, and is dilated
for distant objects. In a dull light also it dilates to let
in more light, and in a bright light it contracts. The
appearance of the pupil is often important as a means
of diagnosis and in etherization.

Lastly there is the innermost sensitive coat or retina,
which has eight layers, the outer one containing some
pigment cells and the next the rods and cones, in which

70 THE ORGANS OF SPECIAL SENSE.

the power of perception is supposed to lie, branches of
the optic nerve being distributed over it in all directions.
In fact, the retina is formed by a membranous expan-
sion of the optic or second cranial nerve, the special
nerve of sight, which passes into the orbit through the
optic foramen at the back and enters the eye-ball close
to the macula lutea or yellow spot. The exact spot where
the optic nerve enters the retina is not sensitive and is
known as the blind spot. In the center of the macula
lutea, however, which is in the middle of the retina pos-
teriorly, is a tiny pit, the fovea centralis, in which all
the layers of the retina except the rods and cones are
absent, and at this point vision is most perfect. It is,
therefore, always turned toward the object looked at,
and when one wishes to see an object distinctly, he must
keep moving his eyes over it that the rays from each
part may fall in turn upon the fovea centralis.

Directly behind the pupil is the crystalline lens,
a rather firm gelatinous body enclosed in a capsule,
which is transparent in life but opaque in death. The
lens is doubly convex and is held in place by the sus-
pensory ligaments, which arise from the ciliary pro-
cesses. In front of it is the anterior chamber of the
eye, filled with a thin watery fluid called the aqueous
humor, while the larger space back of it, occupying
about four-fifths of the entire globe, is filled with a
jelly-like substance known as the vitreous humor.

The chief artery of the eye is the ophthalmic.

Light Rays. — The eye is practically a camera and its
principal function is to reflect images. Although there
are several refracting surfaces and media, for practical
purposes the cornea alone need be considered. Ex-
cept for those rays which enter the eye perpendicu-
larly to the cornea, whose line of entrance is called the
optic axis, all rays are refracted when they enter the eye
and the point at which they meet and cross each other
behind the cornea is called the principal focus of
the eye. To focus properly, all the rays from any one

THE ORGANS OF SPECIAL SENSE.

point on an object must meet again in a common point
upon the retina, their conjugate focus. In the normal
eye all the rays from an object are focused on the ret-
ina and form upon it an image of the object which, as
in the camera, is inverted, because of the crossing of
the rays behind the cornea. Once focused on the ret-

Fio. 26. — Diagram showing the difference between (.4) emmetropic, (B) myopic
and (C) hypermetropic eyes. (American Text-book of Physiology.)

ina the light traverses the various layers to the layer of
rods and cones, where chemical action takes place and
affects the little filaments of the optic nerve, by which
the message is carried to the brain.

When the eye is at rest the pupil and lens are in their
normal condition and at such times the eye sees only

72 THE ORGANS OF SPECIAL SENSE.

distant objects. The ability of the eye to focus upon
objects at different distances is called accommodation
and to accomplish it three things are necessary: 1.
change in the shape of the lens; 2. convergence of the
axes of the eyes, and 3. narrowing of the pupils.

When the eye is directed toward distant objects, the
muscle fibers in the ciliary processes relax, causing
tightening of the suspensory ligaments and consequent
flattening of the surface of the lens. Otherwise an im-
age would be formed in front of the retina; for the
greater the convexity of the lens, the greater the angle
of refraction. Such accommodation is passive and so
not fatiguing. To look at nearby objects, on the con-
trary, the ciliary muscles contract, drawing the cho-
roid forward and allowing the suspensory ligaments
to relax, so that the lens bulges in front. This is an
exertion.

In order to accommodate properly, moreover, both
eyes must work together and the axes of both eyes must
be directed toward the object. Therefore, in looking
at near-by objects the axes of the eyes converge, drawn
by the internal recti muscles. In strabismus or cross
eye, where the axes of both eyes cannot be directed
toward the object at the same time, the rays fall upon
one part of one eye and upon a different part of the
other eye and two separate images are seen.

Finally there is concentric narrowing of the pupil
by contraction of the circular fibers of the iris, by
which means various side rays that would come to a
focus outside the retina are excluded.

All the muscles of accommodation, the ciliary mus-
cles, the internal recti, and the spincter pupillse, are
under the control of the third nerve.

Connected with this power of accommodation and de-
pendent on it are the two conditions of near-sighted-
ness or myopia and far-sightedness or hypermetropia.

The normal eye is emmetropic and is almost per-
fectly spherical, but in the near-sighted or myopic eye

THE ORGANS OF SPECIAL SENSE. 73

the ball, instead of being round, is flattened from above
down and so bulges in front. Consequently, owing to
the greater distance from the lens to the retina, images
are formed in front of the retina. Only nearby
objects can be seen clearly, because the farther the
object from the eye the farther in front of the retina
the image is formed. Concave glasses are worn to en-
able near-sighted people to see at a distance. Hyper-
metropic or far-sighted eyes are flattened from be-
fore backward and can see only objects at a distance
clearly, as those nearby form images behind the retina.
For such eyes convex glasses are worn.

As the ordinary person approaches middle life, he be-
comes able to see better at a distance than near to.
This presbyopia, as it is called, which is practically
far-sightedness, is due to a partial loss of the power of
accommodation in the lens, the result of a general loss
of elasticity in the parts.

Another very common defect is astigmatism, a fail-
ure of the rays to focus upon a point, owing generally
to a flattening in the surface of the cornea.

Color perception is also an important function of the
eye. The waves of hyperluminous ether when of a cer-
tain rate of vibration give the sensation of heat and
when their vibrations are more rapid they give the sen-
sation of light. Each of the primary colors of the spec-
trum gives off a pretty definite number of light rays
which travel through the air and enter the eye, the num-
ber of rays determining the color thrown upon the ret-
ina and the velocity determining the intensity of the
color. Occasionally when light is passing through into
the eye it is broken up as in a prism and the person gets
a sensation as of all sorts of colors, chromatic aberra-
tion. Total or partial absence of sensitiveness to color
is called color blindness. It is commonest in the form
of inability to distinguish between red and green and
is probably due to a defect in the retina.

Sometimes a hair follicle on the lid becomes infected

74 THE ORGANS OF SPECIAL SENSE.

and a sty is formed. Pink eye is conjunctivitis or in-
flammation of the conjunctiva. A Meibomian duct
may become stopped and cause bulging, or there may
be a sagging down or ptosis of the upper lid in certain
diseases, as meningitis, apoplexy, and more especially
syphilis. Rodent ulcer often begins by the eye or on the
cheek.

CHAPTER V.
THE NERVOUS SYSTEM.

The nervous system, which regulates all the vital pro-
cesses of the body, physical and chemical, and which is
situated partly in the head and partly in the trunk, may
well form the connecting link between the description of
the head and that of the trunk. It has two divisions,
the cerebro-spinal system and the sympathetic system.
The former consists of the cerebrum or brain proper, the
cerebellum or little brain, the pons Varolii, the medulla
oblongata, the spinal cord, and the cranial and spinal
nerves; the latter of a series of ganglia or aggregations
of nerve centers. The brain, which includes the cere-
brum, cerebellum, pons, and medulla, occupies the cran-
ium and the spinal cord is contained within the bony
framework of the spinal column. In the male the brain
weighs about 49 ounces and in the female 44, while in
an idiot it seldom weighs more than 23 ounces.

The cerebrum or brain proper has two parts or hem-
ispheres, roughly oval in shape, each of which has five
lobes separated by fissures, the frontal, parietal, occip-
ital, and temporo-sphenoidal lobes, and the central lobe
or island of Reil at the base of the brain. The chief
fissures are the longitudinal fissure, the fissure of Syl-
vius at the base of the brain, and the fissure of Rolando
between the frontal and parietal lobes. There are also
five serous cavities called ventricles, the two lateral and
the third, fourth, and fifth ventricles, of which the first
two, one in either hemisphere, are the most important.
Around these cavities is the brain substance, which is
made up of two tissues, the white and the gray, the latter
forming the outer part of the brain to the depth of

76 THE NERVOUS SYSTEM.

perhaps half an inch, and the white matter forming the
rest. The outer or gray part is called the cortex and
is largely made up of nerve cells. It might be called
the active part of the brain. The white part consists
largely of nerve fibers which are given off from the nerve
cells and are carried down into the spinal cord.

The surface of the brain is convoluted, the ridges
being separated by deep furrows or sulci, by which means
a great extent of gray matter is secured. The furrows
contain fluid from the subarachnoid spaces and vary
in number and depth according to intelligence. While
the convolutions are not uniform in all brains, the prin-
cipal ones are constant.

Both the brain and the spinal cord are covered by
three membranes, the dura mater, the arachnoid, and
the pia mater. The dura mater is dense and fibrous
and lines the interior of the skull, being firmly adherent
to it at many points. In fact, it constitutes the internal
periosteum of the cranial bones. The arachnoid is a
delicate serous membrane, with two layers, lubricated
to prevent friction, which divides the space between
the dura mater and the pia mater, bridging over the
convolutions and enclosing the subdural and subarach-
noid spaces which are connected with lymphatics and
contain a serous secretion, the cerebro-spinal fluid.
This fluid forms an elastic water cushion, on which the
brain rests, and prevents concussion. The pia mater
is vascular, containing blood-vessels, lymphatics, and
nerves, and is closely attached to the surface of the
brain, dipping down into all the sulci.

At the base or under surface of the brain are some
very important structures. The olfactory bulbs lie be-
neath the frontal lobe and projecting back is the olfac-
tory tract, through which the olfactory nerves come from
the brain. Back of the olfactory tract is the optic com-
missure where the optic nerves coming from the brain
cross each other. And back of the commissure again
is the optic tract, where the optic nerves emerge from

THE NERVOUS SYSTEM.

the brain. At the base of the brain are also the exits
of the twelve cranial nerves.

Upon entering the brain the arteries run a tortuous
course, the tortuosity breaking the force of the blood

FIG. 27. — Base of brain. (Leidy.) 1, 2, 3, cerebrum; 4 and 5, longitudinal
fissure; 6, fissure of Sylvius; 7, anterior perforated spaces; 8, infundibulum; 9,
corpora albicantia; 10, posterior perforated space; 11, crura cerebri; 12, pon8
Varolii; 13, junction of spinal cord and medulla oblongata; 14, anterior pyramid;
14X, decussation of anterior pyramid; 15, olivary body; 16, restiform body; 17,
cerebellum; 19, crura cerebelli; 21, olfactory sulcus; 22, olfactory tract; 23, olfac-
tory bulbs; 24, optic commissure; 25, motor oculi nerve; 26, patheticus nerve;
27, trigeminus nerve; 28, abducens nerve; 29, facial nerve; 30, auditory nerve;
31, glossopharyngeal nerve; 32, pneumogastric nerve; 33, spinal accessory nerve;
34, hypoglossal nerve.

stream in the small vessels where congestion would be
with difficulty relieved. The basilar artery, which is
formed by the juncture of the two vertebrals, divides
into the two posterior cerebrals, each of which joins one

78 THE NERVOUS SYSTEM.

of the anterior cerebrals by a posterior communicating
artery. The two anterior cerebrals also are joined by
an anterior communicating artery, thus completing the
circle. The circle thus formed at the base of the brain
is called the circle of Willis and provides for a good
supply of blood in event of an accident to any vessel.
The blood is returned to the general circulation through
the cerebral veins and sinuses formed by the separation
of the dura mater into two layers.

The cerebellum is about one-seventh the size of the
cerebrum and weighs about 5 ounces. It lies in the
lower occipital fossae of the skull and is oblong in shape
and divided into two lateral hemispheres by a trans-
verse fissure. It is made up of both white and gray mat-
ter, of which the former predominates, the gray being
external as in the cerebrum. The cells are about the
same as in the cortex and its surface is traversed by
queer furrows. Of its function little is known but it
probably plays a most important part in the coordi-
nation of the nervous and muscular acts by which the
movements of the body are carried on.

At the back of the cerebrum and below the cerebel-
lum is the pons Varolii, which forms a connecting link
with the medulla oblongata or bulging part of the cord.
It is made up essentially of white matter or nerve
fibers, though there is a small amount of gray matter
in which are found the nuclei of some of the cranial
nerves.

In the medulla oblongata, which is about 1 inch long
and extends from the pons Varolii to the upper border
of the atlas or first cervical vertebra, the gray matter
is not necessarily external to the white but is found in
patches in the white. The gray matter here corresponds
more or less to that of the spinal cord and the white
matter is continuous with that of the cord. From the
medulla arise the fifth to twelfth cranial nerves and the
vasomotor nerves. The cardiac nerve has its center here
and here too are the centers of respiration, phonation,

THE NERVOUS SYSTEM. 79

deglutition, mastication, and expression. In the med-
ulla the nerves that arise in the cerebrum cross over
from one side of the body to the other on the crossed
pyramidal tracts. The importance of this crossing of
the nerve fibers is seen in apoplexy, when a blood-vessel
is ruptured in the brain and hemorrhage causes pres-
sure, generally on the motor tract. Paralysis of the
nerves and of the muscles to which they go results.
The paralysis is generally of one side of the body, the
opposite side from that on which the injury occurred.
The seat of injury in the brain or cord can frequently
be determined by the situation and extent of the
paralysis.

Spinal Cord. — Extending down from the medulla
through the spinal column is the cord. Its length
from the foramen magnum, where it begins, down
through the vertebrae to the lower border of the first
lumbar vertebra, where it ends in a very fine thread-
like process with no special function, called the filum
terminate, is 17 to 18 inches. Just before it ends a
number of nerves are given off in a tail-like expansion
known as the cauda equina or horse's tail. It is not
uniform throughout its length but presents two enlarge-
ments, a cervical enlargement in the lower cervical re-
gion, and a lumbar enlargement in the lower dorsal re-
gion, where the nerves are given off to the arms and
legs respectively. The membranes are the same as
those of the brain and are continuous with them, but
here the dura mater is not attached to the bony walls
enclosing it. For the cord does not fit closely into the
canal but is as it were suspended in it. The subarach-
noid space communicates with the ventricles of the
brain by the foramen of Majendie and is filled with
cerebro-spinal fluid for the protection of the cord. In
cerebro-spinal meningitis or spotted fever this fluid is
infected and for diagnosis lumbar pucture is performed.

If a cross-section of the cord is made, it is found to
have a pretty definite structure. It is roughly cir-

THE NERVOUS SYSTEM.

cular and is divided by certain fissures, of which the
most important are the anterior and posterior median,
the latter being rather a dividing line or septum. By
them it is divided into halves connected by a small
band in the middle called the commissure. The white
matter is exterior to the gray and is divided by it into
four columns, which again are divided into tracts ac-
cording to certain groups of nerves that travel through

FIG. 28.— Different views of a portion of the spinal cord from the cervical
region, with the roots of the nerves. In A the anterior surface of the specimen
is shown, the anterior nerve root of its right side being divided; in B a view
of the right side is given; in C the upper surface is shown; in D the nerve roots
and ganglion are shown from below: 1, the anterior median fissure; 2, posterior
median fissure; 3, anterior lateral depression, over which the anterior nerve roots
are seen to spread; 4, posterior lateral groove, into which the posterior roots are
seen to sink; 5, anterior roots passing the ganglion; 5', in A, the anterior root
divided; 6, the posterior roots, the fibers of which pass into the ganglion, 6; 7, the
united or compound nerve; 7', the posterior primary branch seen in A and D to
be derived in part from the anterior and in part from the posterior root. (Allen
Thomson.)

them. The most important tract is the direct pyram-
idal tract in the anterior column. The gray matter is
arranged in the form of a letter H practically, consist-
ing of two lateral halves, more or less crescentic in out-
line, connected by a narrow band, the gray commissure.
Each half is divided into two horns, the anterior, to-
ward the front of the cord, and the posterior, toward
the back, the former being generally much thicker and
heavier than the latter. The structure of the gray and

THE NERVOUS SYSTEM.

of the white matter is essentially the same as in the
brain, but the proportion varies in different parts of
the cord, the white predominating in the cervical re-
gion and the gray being much better developed in the
lumbar region, where the nerve cells for control of the
lower extremities occur. The gray is least well devel-
oped in the dorsal region. Through the center of the
cord runs a small hole or canal filled with cerebro-spinal
fluid, the central canal of the cord.

FIG. 29. — Functional areas of the cerebral cortex, left hemisphere.
(A. A. Stevens.)

The brain is the seat of intelligence and will, the cen-
ter of all voluntary action. Molecular change in some
part of the cerebral substance is the indispensable
accompaniment of every phenomenon of conscious-
ness. Indeed, -the brain is never in a state of complete
repose, there being dreams even during sleep. The
brain is not sensitive to injury in the sense of pain. It
can be lacerated without much pain.

Various centers exist in the brain, of which the most
important perhaps is the motor center. The visual
center is in the occipital lobe, the auditory center in the

82 THE NERVOUS SYSTEM.

temporal lobe, the speech center in the third left frontal
convolution. Thus the impulses of the senses have
been located, though the function of many parts, the
so-called silent areas, are still in obscurity.

The motor center, that is, the center for motion of the
skeletal muscles, is situated about the fissure of Rolando
and is divided into three parts, one for the legs, one for
the face, and one for the arms, the one for the legs being
uppermost and the others below in the order mentioned.
Fibers from these cells extend down through the brain
and cord to the muscles, the fibers being collected into
well-recognized bundles and the whole known as the motor
tract. There may be one long fiber from a cell in the
brain down through most of the cord or there may be a
succession of shorter fibers that are not actually con-
nected but are in close contact with each other. In the
upper pons the fibers for the face cross to the opposite
side, while the rest keep on down through the medulla,
and as they emerge from the medulla they too cross to
the other side and keep on down in the crossed pyramidal
tract. A few fibers do not cross but come down the
direct pyramidal tract, which, however, disappears part
way down. The crossed pyramidal tract is the true motor
tract and in it the fibers are continually sending branches
to the cells in the gray matter, where they connect with
the anterior horn.

The anatomy of the sensory tract is not so well under-
stood. By it impulses are sent to the brain by the
peripheral organs, practically the surface of the body.
The sensory fibers connect with the sensory cells in the
posterior horn, from, which fibers are sent to the brain,
practically the reverse of motor action. There are
three chief sensory tracts, which are supposed to trans-
mit different sensations, one pain, one muscular sensa-
tions, and the third sensations of touch. All these
tracts, of which the chief is the direct cerebellar tract,
in passing up the cord pass to the opposite side at dif-
ferent levels and then go on to the cortex of the brain.

THE NERVOUS SYSTEM. 83

The action of the nerves is similar to reflex action, only
that an effort of will is needed to send an impulse from
the brain. It is by the help of the brain along this line
that an infinity of artificial reflexes or habits is acquired,
for which volition is needed in the beginning but which
are later done unconsciously. Herein lie the possibilities
of all education.

The brain and spinal cord work together, the cord
acting as a medium between the brain, in which all the
higher psychical processes, such as will, thought, etc.,
originate, and the muscular apparatus. The cord,
however, has some action entirely independent of the
brain, as is seen in reflex action. This action is entirely
involuntary, so that the cord is sometimes spoken of as
the seat of involuntary action, commonly called reflex
action. All unconscious acts are reflex acts, as when
the hand is drawn away from a hot iron. If an impulse
is sent along one of the sensory fibers, it enters the cord
through the posterior horn, where its nerve cell is found.
Then, through some connection between the nerve cell
of the sensory fiber and that of the motor fiber the im-
pulse is transmitted to the motor cell and another impulse
is sent out of the cord along the motor fiber of the nerve
to the muscle. One of the commonest reflexes is the
knee-jerk. Reflex action is important because the re-
flexes are interfered with, delayed, destroyed, or in-
creased in different diseases. The time normally re-
quired for a reflex act is very brief, that for the knee-jerk
being about three one-hundredths of a second.

The nerves of the head, known as the cranial nerves,
arise from the brain, while the rest of the body is sup-
plied by the spinal nerves, which come off at intervals
from the spinal cord. The cranial nerves consist of
twelve pairs: (1) The olfactory or nerve of smell, (2)
the optic or nerve of sight, (3) the motor oculi, (4) the
patheticus, which controls the eye, (5) the trigeminus
or trifacial, a nerve of general sensation, motion, and
taste, (6) the abducens, a motor nerve, (7) the facial

84 THE NERVOUS SYSTEM.

nerve of the face, ear, palate, and tongue, (8) the au-
ditory or nerve of hearing, (9) the glosso-pharyngeal,
nerve of sensation and taste, (10) the pneumogastric
or vagus, which is both motor and sentory and governs
respiration, the heart, and the stomach, (11) the spinal
accessory, to the muscles of the soft palate, and (12)
the hypoglossal, the motor nerve to the tongue.

The spinal nerves also are arranged in pairs: Eight
cervical pairs, twelve dorsal or thoracic, five lumbar, five
sacral, and one coccygeal, these titles denoting their
point of origin near the vertebra of the same name.
Each of these nerves arises by two roots, an anterior
motor root from the anterior horn of gray matter and a
posterior sensory root from the posterior horn, the latter
having a ganglion upon it. After emerging from the
cord the two roots unite to form the nerve, that the
nerve may contain both motor and sensory fibers. The
motor fibers are called efferent because they carry im-
pulses from the cord, while the sensory are called afferent
because they carry impulses back to the cord. After
leaving the cord the nerves unite to form plexuses, which
again divide into various nerve trunks and are distrib-
uted to the muscles.

The first cervical nerves pass out of the spinal column
above the first cervical vertebra and the other cervical
nerves below that and the succeeding vertebrae, while
the other spinal nerves emerge each below the corre-
sponding vertebra, as the first dorsal below the first
dorsal vertebra, etc. After emerging they break up
into a large anterior division and a small posterior
division, the posterior branches supplying the spine and
the dorsal muscles and skin, the anterior the rest of the
trunk and the limbs. The cervical plexus is formed by
the anterior divisions of the first four cervical nerves,
the brachial plexus by the last four cervical and the first
dorsal or thoracic nerves, the lumbar plexus by the four
upper lumbar, and the sacral plexus by the last lumbar
and the four upper sacral nerves.

THE NERVOUS SYSTEM. 85

The only important branch of any of the four upper
cervical nerves, which in general supply the neck and
shoulders, is the phrenic, which is distributed to the
pericardium, the pleura, and the under surface of the
diaphragm.

The brachial plexus, as its name implies, supplies
the arms and has a number of important branches, as
the circumflex to the shoulder, the musculo-cutaneous
to the upper arm, the elbow-joint, and the outer sur-
face of the forearm, the internal cutaneous to the inner
side of the arm, the median to the pronators and
flexors and the fingers on the radial side, and the ulnar
to the elbow and wrist-joint. The musculo-spiral runs
down the spiral groove to the external condyle of the
humerus or upper arm bone, where it divides into the
radial and the posterior interosseous, the former going
to the thumb and two adjacent fingers and the latter to
the wrist-joint and the muscles on the back of the fore-
arm. Sometimes, in fracture of the humerus the callus
thrown out pinches the musculo-spiral and causes pain.

The dorsal or thoracic nerves supply the back with their
posterior divisions and their anterior divisions are the
intercostal nerves.

The lumbar nerves supply the abdomen, pelvis, and
thigh, the chief branches being the ilio-hypogastric to
the abdomen and gluteal region, the ilio-inguirial to the
inguinal region and scrotum, the external cutaneous and
genito-crural to the thigh, and the obturator to the thigh
and the hip and knee-joints. The anterior crural de-
scends beneath Poupart's ligament and divides into an
anterior and a posterior division which supply the thigh
muscles, its branches going to the pelvis.

The sacral plexus supplies the organs of the pelvis,
the thigh, and the leg. Its chief branches are the great
sciatic, the largest nerve in the body, and the small sci-
atic, which go to the buttocks and thigh. The great
sciatic runs down the back of the thigh and divides at
the lower third of the thigh into the internal and external

THE NERVOUS SYSTEM.

popliteal nerves, the former of which passes along the
back of the thigh to the knee, where it becomes the

FIG. 30. — Diagrammatic view of the sympathetic cord of the right side, show-
ing its connections with the principal cerebro-spinal nerves and the main preaortic
plexuses. (Reduced from Quain's anatomy.)

posterior tibial, which in turn divides at the ankle into
the internal and external plantar. The external popli-

THE NERVOUS SYSTEM. 87

teal descends along the outer side of the popliteal space
and divides an inch below the head of the fibula into
the anterior tibial, which supplies the flexors and skin
of the ankle-joint, and the musculo-cutaneous, which
sends branches to the skin of the lower leg and the dor-
sum of the foot.

The Sympathetic System. — Joined to the cerebro-spinal
system by intervening cords is the sympathetic system.
This is made up of two series of ganglia, one on either
side of the spinal column, connected by longitudinal
bands and extending from the base of the skull to the
coccyx. They do not form an independent nervous
system, each ganglion, which seems to resemble the
motor cells of the spinal cord, being connected by motor
and sensory fibers with the cerebral system.

The sympathetic nerves are mostly gray, non-medul-
lated fibers and are distributed to viscera, secreting
glands, and blood-vessels, whose movements are in-
voluntary and feelings obtuse. They form networks
upon the heart and other viscera and send branehes to
the cranium to the organs of special sense. There are
three main plexuses: The solar plexus behind the stom-
ach, which supplies the abdominal viscera; the hypo-
gastric plexus in front of the prominence of the sacrum,
whose nerves go to the pelvic organs; and the cardiac
plexus behind the aortic arch for the thoracic viscera.

Over these nerves one has no control. A blow in the
region between the costal cartilages and below the ster-
num is a solar plexus blow and is very upsetting.

The sympathetic system serves to maintain vitality
in all the important portions of the system and one of
its important functions is to keep up communication
between one part and another, so that when any organ
is affected the others will act accordingly and help out
to the best of their ability.

CHAPTER VI.
THE BACK.

The Spine. — The trunk may be roughly
divided into the back, the chest or thorax,
the abdomen, and the pelvis. By the
back is denoted the spinal column with its
muscles, blood-vessels, etc., and the spinal
cord already described. The spine or
vertebral column, which serves the double
purpose of holding the body erect and of
protecting the cord, is usually about two
feet, two inches in length. In its course
there occur several curves, which serve to
give springiness and strength and, with
the intervertebral cartilages, to mitigate
the force of concussion from blows and
falls. The curve is convex forward in the
cervical region, convex backward in the
dorsal, forward in the lumbar, and back-
ward again in the sacral region. There is
most freedom of motion in the cervical
region.

As is the case with the other bones, the
vertebrae are specially adapted in shape and
size to the needs they are called upon to
fill. Strength and flexibility, with a mini-
mum bulk, a channel for the cord, and
passages for the numerous nerves and
blood-vessels are some of the requirements
which, in combination, they meet to an
astonishing degree. They are thirty-three
in all, and are divided into groups according
Fio 31 _The to the region in which they occur: seven cer-
spinai column, vical in the neck, twelve dorsal or thoracic,
' five lumbar, five sacral, and four coccygeal.
88

THE BACK. 89

Although the vertebrae of the different groups differ
more or less in size and shape in accordance with the
various demands of their positions, they all have certain
general characteristics. Each has a body, two laminae, two
pedicles, two transverse processes, and one spinous pro-
cess. The pedicles extend back from the body on either
side and support two broad plates of bone, the lamince,
whose juncture at the back completes the spinal foramen
for the passage of the cord. At their juncture is the
spinous process, which can be felt beneath the skin, while
the transverse processes project from the juncture of the

FIG. 32.— A type of vertebra. (Leidy.) 1, Body; 2, pedicle; 3, lamina; 4,
spinal foramen; 5, spinous process; 6, transverse process; 7, articular process.

laminae with the pedicles. All the processes are for the
attachment of muscles that move the spine. The body
is formed of cancellous bone with a compact layer outside.
Transversely it is slightly oval, while its upper and lower
surfaces are flat, except in the crevical region, where the
upper surface is concave laterally and the under convex
laterally and concave from before back. Between the
bodies are disks of fibro-cartilage, which increases motion
and springiness. The spinous process or spine is short
in the cervical region, long and directed downward in the
dorsal region, thick and projecting almost straight out in
the lumbar region. The pedicles are notched above and
below so that when articulated the notches of two verte-

90 THE BACK.

brae join to form the intervertebral foramen for the out-
ward passage of nerves and the inward passage of blood-
vessels.

The distinguishing mark of the cervical vertebra is the
foramen in each transverse process, through which the
vertebral arteries run to the skull. They are also smaller
than the dorsal and lumbar vertebrae. The dorsal vertebra
are distinguished by having on the transverse processes
and on the body smooth articular surfaces called facets
and demi-f acets for articulation with the ribs. The lumbar

FIG. 33.— The sacrum, from before. (Drawn by D. Gunn.)

vertebrce are the largest and heaviest and have the thickest
spine. By the time the sacral region is reached, however,
the vertebrae have only a rudimentary spinous process.
Moreover, in adult age the sacral bones grow together
and form one triangular bone, the sacrum, which has a
broad base called the promontory of the sacrum and a blunt
apex. It is concave in front and convex behind and has an
articulating surface for joining the pelvic bones. In the
case of the coccyx also the four original bones, all rudi-
mentary in character and supposed to be the survival of a
tail, grow together to form one bone. Together the sacrum
and coccyx form the posterior wall of the true pelvis.

THE BACK. 91

Some of the dorsal vertebrae are peculiar in the arrange-
ment of their facets and derm-facets, while among the
cervical vertebrae are several whose peculiarities should be
more carefully noted. Thus, the first cervical vertebra
or a^as supports the head and has practically no body,
the place of the body being taken by a narrow anterior
arch of bone and an opening, continuous with the spinal
foramen, into which the odontoid process of the axis fits,
being held in place by ligaments. At either side on top
is a facet for articulation with the occipital bone. There
is almost no spine. The second vertebra or axis has
surmounting the body the odontoid process, with a facet
in front for articulation with the atlas and one behind
for the transverse ligament to move over. The seventh
cervical vertebra or vertebra prominens has a very long
spinous process — hence name — to which is attached the
liyamentum nuchce. It can be felt very distinctly on
the living.

Running from the skull down through the spinal
column into the sacral vertebrae and formed by the join-
ing of the spinal foramina of the individual vertebras is an
opening called the spinal canal, which holds the cord.
The cord, however, stops practically at the first lum-
bar vertebra, where it splits up into the cauda equina,
only the filum terminate extending farther down.

Occasionally the laminae do not form completely and
the membranes of the cord may bulge out and form a
tumor, or the cord itself may come out also. This
generally occurs in the lumbar region, where it is known
as spina bifida. If in case of fracture of a vertebra there
is paralysis of the parts below due simply to the pressure
of a fragment of bone upon the cord, it may be completely
cured by remoyal of the fragment. If, however, the
cord suffers injury, the paralysis will remain. Humpback
or Pott's disease is caused by the tubercle bacillus, which
eats away the bodies of the vertebra? so that the column
caves in and the spinous processes are thrown out in a
hump or kyphos.

92 THE BACK.

Muscles of the Neck. — Before speaking of the muscles
of the back a few of those of the neck had best be taken
up. They are numerous but mostly of minor importance.
Largest and most important is the sterno-cleido-mastoid
muscle, which has its origin on the upper part of the
sternum and the inner third of the clavicle and is in-
serted into the mastoid process of the temporal bone.
It passes obliquely across the side of the neck and

FIG. 34. — Muscles of the right side of the head and neck: 1, Frontalis; 2, supe-
rior auricular; 3, posterior auricular; 4, orbicularis palpebrarum; 5, pyramidalis
nasi; 6, compressor naris; 7, leyator labii superiqris alseque nasi; 8, levator labii
superioris; 9, zygomaticus major; 10, orbicularis oris; 11, depressor labii in-
ferioris; 12, depressor angulioris; 13, anterior belly of digastric ;14, mylohyoid;
15, hyoglossus; 16, stylohyoid; 17, posterior belly of digastric; 18, the masseter;
19, sternohyoid; 20, anterior belly of omohyoid; 21, thyrohyoid; 22, 23, lower
and middle constrictors of pharynx; 24, sternomastoid; 25, 26, splenius; 27, leva-
tor scapulae; 28, anterior scalenus; 29, posterior belly of omohyoid; 30, middle
and posterior scalenus; 31, trapezius. (Borland's Dictionary.)

serves to flex the head to the side and to draw the face
in the opposite direction. When both muscles contract
the head is flexed on the neck and the neck on the
chest. In wry neck or torticollis this muscle is constantly
contracted. The platysma myoides arises from the fascia
over the pectoral, deltoid, and trapezius muscles and is
inserted into the lower jaw, the angle of the mouth, and
the loose tissue in the lower part of the face. It

THE BACK. 93

wrinkles the skin of the neck and depresses the lower
jaw. In the cow and horse it is so highly developed
that by it the skin can be contracted all over the body to
drive off flies. The rectus capitis anticus major arises
from the third to the sixth cervical vertebrae and is in-
serted into the occipital bone, serving to flex the head.
The scalenus muscles have their origin on the lower cer-
vical vertebrae and are inserted into the first and second
ribs, thus aiding in the elevation of the ribs as well as in
lateral flexion of the neck. The head is held upright by
the ligamentum nuchce, which rises from the external
occipital protuberance and is inserted into the spinous
processes of all the cervical vertebrae except the first.

Muscles of the Back. — The chief back muscles are the
trapezius and the latissimus dorsi, which together cover
in the back pretty thoroughly. The trapezius arises
from the occipital bone, the ligamentum nuchae, and the
spinous processes of the seventh cervical and all the
dorsal vertebrae and is inserted into the outer third of the
clavicle or collar bone and the acromion process and spine
of the scapula or shoulder blade. It is thus triangular in
shape and covers in the neck and shoulders, serving to
draw the head back and to the side. It overlaps the
latissimus dorsi.

The latissimus dorsi has its origin by aponeurosis from
the spinous processes of the six lower dorsal and all the
lumbar and sacral vertebrae, from the crest of the ilium or
hip bone, and from the three or four lower ribs, swings
across the side, dwindling in size, and is inserted by a
small tendon into the bicipital groove of the humerus or
upper arm bone, thus covering in the part of the back
not covered by the trapezius. It draws the arm down
and back, raises the lower ribs, and draws the trunk for-
ward, as in climbing. The flat muscles of the back and
abdomen have a tendency to flatten out into aponeuroses,
such as occurs in the origin of the latissimus dorsi.

The levator scapulas, from the transverse processes of
the upper cervical vertebrae to the posterior border of the

THE BACK.

scapula, serves to raise the angle of the scapula, and the
rhomboideus major and minor, from the ligamentum
nuchae, the seventh cervical, and the upper dorsal verte-

FIG. 35. — Muscles of the trunk from behind (left side, superficial; right side,
deep): 1, Sternomastoid ; 2, splenius; 3, trapezius; 4, latissimus dorsi; 5, infra-
spinatus; 6, teres minor; 7, teres major; 8, deltoid; 9, external oblique of abdomen;
10, gluteus medius; 11, gluteus maximus, 12, levator anguli scapulae; 13, rhomboi-
deus minor; 14, rhomboideus major; 15, part of longissimus dorsi; 16, tendons of
insertion of iliocostalis; 17, supraspinatus; 18, inf raspinatus ; 19, teres minor; 20,
teres major; 21, serratus magnus; 22, upper, and 22', lower part of serratus posti-
cus inferior; 23, internal oblique; 24, gluteus medius; 25, pyriformis and superior
and inferior gemelli; 26, 26', portions of obturator interims; 27, tendon of obtu-
rator in tern us; 28, quadratus femoris. (Borland's Dictionary.)

brae to the root of the spine of the scapula, draw the in-
ferior angle back and up.

The blood supply in the cervical region and about the
shoulders comes from branches of the subclavian artery,
such as the suprascapular and the transversalis colli.

THE BACK. 95

Lower down the supply comes from the posterior
branches of the intercostals, dorsal branches of the lum-
bar, and branches of the internal iliac.

The muscles of the back are supplied by the spinal
nerves, the spinal accessory also going to the trapezius
muscle.

CHAPTER VII.
THE CHEST.

The chest or thorax occupies the upper part of the
trunk in front and is a dome-shaped cavity containing
and protecting the heart and lungs. Its walls are formed
by the dorsal vertebrae at the back, the ribs at either side,
and the sternum and costal cartilages in front, all well

Circumference of apex of thorax.

First rib.

Second rib.

Third rib.

Seventh rib.

Eighth rib.

Ninth rib.-
Tenth rib

Eleventh rib,

Manubrium
sterni.

Costal cartilages.
Gladiolus.

Ensiform carti-
lage or xiphoid
appendix.

Eleventh rib.

Circumference of base.
FIG. 36. — Thorax (anterior view.) (Ingals.)

covered with muscles. The floor is formed by the
diaphragm. Through the upper opening of the chest
pass the trachea, the esophagus, and many important
vessels and nerves.

The shape of the chest may vary in disease. Thus, in

THE CHEST.

rickets there is the prominent "pigeon" breast and the
rosary, that is, a bead at the juncture of each rib with
the costal cartilage, while in emphysema the chest is
enlarged in all directions and barrel-shaped. In severe
cases of lateral curvature it is distorted but may be im-
proved by exercises.

The Sternum. — The sternum or breast-bone is a long
narrow bone and has three parts, the manubrium or han-
dle above, the gladiolus or sword, and the ensiform
cartilage at the lower end. On either side are notches
for the costal cartilages; for the first seven ribs as well as
the clavicle articulate with it. Except for some muscles
along the edges it lies directly under the skin and the
ridge between the manubrium and the gladiolus can be
felt in the living, a fact which assists in determining the
position of the different ribs in cases of fracture, as the
second rib articulates at this point.

FIG. 37.— A and B, typical ribs; C, first rib; D, twelfth rib. 1, head; 2, neck;
3, tuberosity; 4, grooved edge; 5, shaft; 6, oval depression for costa cartilage.

The Ribs. — The ribs are twenty-four in number,
twelve on each side, of which the upper seven, which
articulate with the sternum by individual cartilages, are
called true ribs, the other five false ribs. Of the false ribs
the upper three articulate indirectly with the sternum
through the seventh cartilage, with which their cartilages
unite, while the other two have their anterior extremities
free and are called floating ribs. All the ribs slope down
7

98 THE CHEST.

toward the front and are by nature more freely movable
in women than in men. Most of the ribs have a head
divided by a little ridge into two facets for articulation
with the dorsal vertebrae, a flattened neck, a tuberosity at
the base of the neck with a facet for articulation with the
transverse process of the vertebra below, an angle, and
a shaft, which is externally convex and is grooved on its
lower edge for the intercostal vessels and nerve. The
first and second, eleventh and twelfth ribs, however, are
somewhat peculiar, the first two being shorter, flatter
and rather broader than the rest and the first having only
one facet on the head, while the last two have only one
facet on the head and no neck or tuberosity.

The costal cartilages serve to prolong the ribs and
greatly increase the elasticity of the chest wall. They
grow longer down to the seventh and then decrease again
in length.

The ribs, except the first and second, which are pro-
tected by the clavicle, are frequently broken. Such a
break causes pain in breathing and sometimes the end of
a rib pierces the lung tissue and swelling all over the
body results, due to the presence of air. Caries or death
of the rib is also frequent. Fracture of the sternum occurs
occasionally, generally from direct force, as from a blow
with the knee in foot-ball, and there may be dislocation
between the manubrium and gladiolus.

Muscles of the Chest. — The spaces between the ribs,
from the tubercle of the rib behind to the cartilage in
front, are filled by the external intercostal muscles, which
pass downward and forward from the lower border of
one rib to the upper border of the one below. There
are, therefore, eleven pairs of these muscles. There are
also eleven pairs of the internal intercostals , which com-
mence at the sternum and extend back to the angle of
the rib. These extend downward and backward. The
external intercostals raise and evert the ribs in inspira-
tion, the internal depress and invert them in expiration.

The chief respiratory muscle, however, is the dia-

THE CHEST. 99

phragm, a somewhat fan-shaped muscle that forms the
floor of the chest cavity. It takes its origin from the
ensiform cartilage, the six or seven lower ribs and their
cartilages, and from the upper three or four lumbar
vertebrae, that is, from the whole of the internal circum-
ference of the thorax, and is inserted into the central
cordiform tendon. It has several large and several
small openings for the aorta, the esophagus, the venae
cavse, the thoracic duct, and various nerves, and its

FIG. 38. — Interior view of the diaphragm. (Leidy.) 1-3, The three lobes
of the central tendon, surrounded by the fleshy fasciculi derived from the inferior
margin of the thorax; 4, 5, the crura; 6, 7, the arcuate ligaments; 8, aortic orifice;
9, esophageal orifice; 10, quadrate foramen; 11, psoas muscle; 12, quadrate
lumbar muscle.

surfaces are covered by serous membranes, by the two
pleurae and the pericardium above and by the peritoneum
below. It partially supports the heart and lungs. Con-
vex toward the chest, it becomes flattened in contraction
and so increases the capacity of the chest. It aids in all
expulsive acts, as sneezing, coughing, laughing, urinat-
ing, defecating, vomiting, and childbirth. Hiccough is
spasm of the diaphragm.

The arteries of the chest are the intercostal branches

100 THE CHEST.

of the subclavian and the thoracic aorta, the phrenic,
mediastinal, and intercostal branches of the internal
mammary, and the thoracic branches of the axillary.

The nerves are the intercostals and phrenics.

Mammary Glands. — On the outside of the chest walls,
lodged in the fascia of the pectoral muscles, are the
mammary glands, accessory organs of the generative
system. They exist in both sexes but are only rudimen-
tary in the male. In the female they are small before
puberty but enlarge as the generative organs become
more completely developed, forming two hemispherical
eminences, one on either side, between the third and
seventh ribs. During pregnancy they increase once more
in size preparatory to the secretion of the milk, and in
old age they atrophy. From the middle projects a small
pinkish-brown conical eminence, the nipple, surrounded
by a paler area, the areola. After the second month of
pregnancy both nipple and areola become darker in color,
a point of great diagnostic value in early pregnancy.

The mammary glands themselves consist of lobules of
gland tissue with a central lactiferous tubule, the lobules
being gathered into lobes with fatty tissue between.
From the juncture of these tubules result fifteen or
twenty excretory ducts, the tubuli lactiferi, which con-
verge toward the areola. Beneath the nipple they dilate,
forming the ampullce, and then contract again to pass out
through the nipple as straight tubes.

Breast abscess occurs most commonly in nursing
mothers, as where a part is most active there is most dan-
ger of abscess. Many benign tumors of the breast, as the
fibrous tumors, occur and are especially common in
young women. If a fibrous tumor is allowed to develop
it may become cancerous. Cancer, however, generally
occurs after the age of forty and is usually due to some
irritation, as to a blow from a ball.

The arteries of the breasts are the thoracic branches of
the axillary, the intercostal, and the internal mammary.

The nerves are from the thoracic cutaneous.

CHAPTER VIII.
THE HEART AND CIRCULATION.

The Heart. — Shielded within the chest are, as has been
said, the heart and lungs. The heart lies on the left side
behind the sternum and the cartilages of the fourth to
seventh ribs in a closed, conical, membranous sac, the

FIG. 39.— The heart. (Stoney.)

pericardium, which is attached by its base to the central
tendon of the diaphragm, and whose point extends up
between the pleurae of the lungs. This sac has an exter-
nal fibrous layer and an internal serous layer that is re-
flected back over the heart itself, forming a closed sac,

101

TH-3 HP ART. .AND CIRCULATION.

within which a thin fluid is secreted that serves to reduce
friction during the movements of the heart, the two inner
surfaces sliding over each other with every beat.

The heart itself is a hollow conical organ composed of
cardiac muscle, a combination of smooth and striated
fibers found nowhere else in the body. It lies obliquely,

FIG. 40.— Left auricle and ventricle, opened and part of their walls removed
to show their cavities: 1, Right pulmonary vein cut short; 1', cavity of left auricle;
3, 3', thick wall of left ventricle; 4, portion of same with papillary muscle
attached; 5, the other papillary muscles; 6. 6', the segments of the mitral valve;
7, in aorta is placed over the semilunar valves; 8, pulmonary artery; 10, aorta
and its branches. (Allen Thomson.)

base up, between the lungs, suspended by the great blood-
vessels and with the apex directed downward, forward,
and to the left, the apex beat being normally felt in the
fifth intercostal space, one inch inside and two inches
below the left nipple. In size it varies in different peo-
ple and is generally smaller in women than in men. On
the average it is five inches long, three and a half

THE HEART AND CIRCULATION. 103

inches broad, and two inches thick. A man's heart
usually weighs about eleven ounces and that of a woman
nine ounces. It never leaks except from disease and
such leakage is fatal.

The Cavities. — The heart contains four cavities, two
auricles above and two ventricles below, with a longi-
tudinal septum between the auricle and ventricle on the
right and those on the left. The posterior surface is
largely made up of the left ventricle and the anterior of
the right ventricle. The right auricle, which receives
the blood from the general circulation, has a capacity
of about two fluid ounces and is larger than the left,
which receives the blood returning from the lungs,
though its walls are thinner. Of the ventricles the left

IVJ.

lV3 \

RAV

FIG. 41. — Orifices of the heart, seen from above, both the auricles and the
great vessels being removed: PA, Pulmonary artery and its semilunar valves;
Ao, aorta and its valves; RAV, tricuspid, and LAV, bicuspid valves; mv, seg-
ments of mitral valve; Iv, segment of tricuspid valve. (Huxley.)

is the larger and its walls are about three times as thick
as those of the right, for it has to send the blood all over
the body. All the cavities are lined with smooth, trans-
parent, serous membrane, the endocardium, which is con-
tinuous with the intima of the great vessels.

The Valves. — The opening from the auricle into the
ventricle on either side is guarded on the ventral side by
a valve formed of folds of endocardium. The valve on
the right side has three flaps or cusps and is called the

104 THE HEART AND CIRCULATION.

tricuspid valve, while that on the left has two flaps, larger
and thicker than those of the tricuspid, and is known as
the bicuspid or mitral valve. The flaps of either valve are
kept from being forced into the auricle in closing by fine
tendinous cords, the chordce tendinece, which are attached
to the columnce carnece, muscular bands or columns pro-
jecting from the walls of the ventricle, which contract
and hold the chordae tendineae taut. The opening into
the pulmonary artery is from the posterior part of the
right ventricle and is guarded by the semilunar or pulmo-
nary valve, while the aortic opening from the left ventricle
is guarded by a similar valve, the aortic valve, the most
important valve in the body. All these valves are planned
primarily to prevent regurgitation of the blood during
contraction of the heart muscle. Pressure in the ven-
tricle must exceed that in the arteries before the semi-
lunar valves will open and the blood can be driven out,
just as the auriculo-ventricular valves remain closed until
the pressure in the auricles exceeds that in the
ventricles.

The heart beat is caused by the twisting of the heart
upon its axis during contraction of the muscle. Nor-
mally it beats rhythmically and regularly, whatever a
person does, at a rate of about seventy-two contractions
to the minute in the adult. To the regular cardiac cycle,
as it is called, there are two periods, the systole and the
diastole, the former representing the period of contraction
of the ventricles, when the blood is sent to the lungs and
over the body, and the latter representing the period of
rest following the emptying of the ventricles, during
which they are refilled. Contraction of the heart occu-
pies one-fifth of the time of one beat, dilatation two-fifths,
and the pause two-fifths. There are really two systoles,
one of the auricles and one of the ventricles, but they
come so close together that they are practically simul-
taneous so far as sound is concerned, though they can be
distinguished by sight. During systole the tricuspid
and mitral valves close sharply to prevent regurgitation

THE HEART AND CIRCULATION.

105

into the auricles, while the semilunar valves open to let
the blood out. The cardiac cycle is, therefore, as follows:
Circulation. — The blood, after it has given off its oxy-
gen and collected carbon dioxide, returns to the heart
through two main channels, the superior and inferior vence
cavce, the former bringing the blood from the upper part of

Pulmonary
artery

Superior
vena cava

Right auricle
Inferior
vena cava
Right
ventricle

Pulmonary
capillaries

-* Left ventricle

Portal
circulation

Systemic
capillaries

FIG. 42. — Diagram of the circulation. (After Kirke.)

the body, including the head, neck, and arms, and the lat-
ter from the lower part below the diaphragm. The two
vessels empty along with the coronary sinus, which is
guarded by the coronary valve, into the right auricle. At
the same time that they empty into this auricle the four
pulmonary veins, the only veins that carry arterial or
oxygenated blood, are emptying the fresh blood from the
lungs into the left auricle. When both auricles are full,

106

THE HEART AND CIRCULATION.

they contract and send the blood into the ventricles, the
auricular systole. As the blood comes through into the
ventricles it probably comes around by the walls and
closes the auriculo-ventricular valves, though just how
the valves close is not certain. When the two ventricles
are full they in turn contract, the ventricular systole,
and the blood is forced out, that in the right ventricle
passing to the lungs for its new supply of oxygen through
the pulmonary artery, the only artery to carry venous
blood, and that from the left ventricle entering the aorta
for general distribution through the body. Following
the systole is a pause, the diastole, while the heart fills
again.

Circulation in Fetus. — In the fetus there is direct com-
munication between the two auricles through the
foramen ovale, which normally
closes at birth, though occa-
sionally it remains open. There
is also communication between

arch of the aorta through the
ductus arteriosus. The freshly
oxidized blood comes to the
fetus through the placenta, from
which it is brought along the
umbilical cord in the umbilical
vein to the liver and thence to
the inferior vena cava, where it
mixes with the blood from the
lower extremities. By the in-
ferior vena cava it is carried to the right auricle, where
the Eustachian valve — a valve between the inferior vena
cava and the auriculo-ventricular opening, larger in the
fetus than in later life where it serves no special purpose
— guides it across the auricle and through the foramen
ovale to the left auricle. From this auricle, together with
a small amount of blood from the lungs, it goes to the left
ventricle and is distributed by the aorta almost entirely

FIG. 43. — The fetal circulation.

THE HEART AND CIRCULATION. 107

to the head and upper extremities. Hence their large size
and perfect development at birth. Returned from the
upper extremities by the superior vena cava, the blood
enters the right auricle again and, passing over the
Eustachian valve this time, descends to the right ven-
tricle, from which the greater part passes by the pul-
monary artery and the ductus arteriosus to the descend-
ing aorta, though a small amount keeps on through the
pulmonary artery to the lungs. In the aorta it mixes
with the blood from the left ventricle and part goes to
supply the lower extremities, though the greater part is
carried back to the placenta through the two umbilical
arteries. The fact that the greater part of the blood
traverses the liver accounts for its large size at birth,
while the lower extremities, which receive for the most
part blood that has already circulated through the upper
extremities, are of small size and imperfectly developed.

Arteries. — After birth the arterial blood for the gen-
eral circulation leaves the heart by the aorta, the main
distributing artery of the body. Through this and
its branches it is carried throughout the body in what,
with the return of the venous blood by the venae cavae
and other smaller veins, is known as the systemic circula-
tion. The aorta ascends from the left ventricle and
arches backward to the left over the root of the left
lung to descend along the spinal column at the left to
the fourth lumbar vertebra, about opposite the umbilicus,
where, considerably diminished in size by the branches
it has given off, it divides into the two common iliacs.
For convenience its different parts are named, according
to their position, the ascending aorta, the arch of the
aorta, and the descending aorta, the last being subdivided
into the thoracic and the abdominal aorta.

From the ascending aorta come off the coronary
arteries which supply the heart muscle itself, as the cor-
onary sinuses carry off the venous blood from the
heart. . From the arch are given off the left common
carotid and left subclavian and the innominate, which

108

THE HEART AND CIRCULATION.

divides into the right common carotid and right sub-
clavian.

The common carotids pass up the neck behind the
sterno-cleido-mastoid muscles in a line from the sterno-
clavicular joint to a point mid-
way between the mastoid process
and the angle of the lower jaw
and divide opposite the upper
border of the thyroid cartilage
into the internal and external
carotids, of which the former with
its branches supplies the anterior
part of the brain, the eye and
forehead, and the latter the neck
and face.

The subclavian is the artery of
the upper extremity but its
vertebral branch goes to the
brain, where with its fellow it
forms the basilar artery, whose
branches together with the
branches of the internal carotid
form the circle of Willis at the
base of the brain. Other branches
of the subclavian are the thyroid
axis, with branches to the neck
and shoulders; the internal mam-
mary, with branches to the chest
walls, mediastinum, and dia-
phragm, such as the musculo-
phrenic and superior epigastric;
and the superior intercostal. At
FIG. 44.— The aortjB and their the lower border of the first rib,
over which it passes, the name

axillary is substituted for subclavian, while at the lower
border of the axilla, where it starts down the arm, it
is called the brachial artery. At the elbow the brachial
divides into the radial and ulnar arteries. The axillary

THE HEART AND CIRCULATION. 109

artery sends branches to the chest and shoulder and is
more frequently injured than any other artery except
the popliteal. Aneurism may occur in it and is very
likely to occur in the thoracic aorta.

From the thoracic aorta branches go to various of the
chest contents, while the abdominal aorta supplies the
abdominal viscera. Among the branches of the abdomi-
nal aorta are: the celiac axis, which has a gastric, an
hepatic, and a splenic branch; the superior and inferior
mesenteric to the intestines; the renal; the suprarenal;
the spermatic or ovarian; the inferior phrenic; and the
lumbar.

The common iliacs divide at the upper edge of the sa-
crum into the external and internal iliacs, of which the
latter with its branches supplies the walls and viscera of
the pelvis and the inner part of the thigh. The external
iliac and its branches go to the thigh, leg, and foot.

Veins. — Of the veins few need be mentioned by name.
The deep veins have the same names as the arteries they
accompany, though there are two innominate veins where
there is only one innominate artery, the subclavian and
internal jugular veins on either side joining to form an in-
nominate vein and the two innominates in turn forming
the superior vena cava. Of the superficial veins the
external and internal jugular correspond to the common
carotid arteries and return the blood from the head and
face. The external jugular vein is important because it
is the largest superficial vein in the neck and is often cut
in suicide. The median vein is found at the bend of the
elbow and is used in letting blood and in giving salt
solution, while the basilic is on the inner side and the
median cephalic on the outer side of the upper arm.
Varicosity often occurs in the internal or long saphenous
. and the external or short saphenous in the leg. The in-
ferior vena cava is formed by the juncture of the two
common iliac veins.

Portal Circulation. — The portal system of veins includes
four large trunks which collect the blood from the viscera

110 THE HEART AND CIRCULATION.

of digestion, the superior and inferior mesenteric veins
from the intestines, the splenic vein from the spleen, and
the gastric from the stomach. These join together to
form the portal vein, the only vein that breaks up into
capillaries. This divides and ramifies through the liver,
whence it emerges as the hepatic veins. The whole is
known as the portal circulation.

Pulmonary Circulation. — Of the pulmonary circulation
and its vessels a few words might also be said. The pul-
monary artery, which carries the blood from the right
ventricle to the lungs, is only about two inches long and
divides into a right and a left pulmonary artery, which
pierce the pericardium and go to their respective lungs.
The right one is the larger and longer, for it has farther to
go and gives off a branch to supply the third lobe of the
right lung. The vessels finally divide and subdivide,
terminating in the pulmonary capillaries. The venous
capillaries then gather together to form a main vein in
each lobule, these veins uniting into two trunks for each
lung, the pulmonary veins, which empty into the left
auricle.

Nerves of Heart. — The muscular fibers of the heart
have the power of rhythmical contraction. Independent
nerve centers or ganglia are also found in the muscular
walls and influence the mechanism of the heart, especi-
ally the acceleratory mechanism. Thus, in some of the
lower animals the heart can be removed from the body,
and if placed in normal salt solution will go on beating
for some time. The heart is controlled, however, by two
nerves, the vagus or pneumogastric and the sympathetic.
Of these the vagus is the inhibitory mechanism. It acts
as a check and makes the heart's action regular and
rhythmic. If it is cut, the action of the heart becomes very
rapid and irregular. The sympathetic is the acceleratory
mechanism. When the vagus alone is stimulated, it
first slows, then stops the heart, for it weakens the systole
and prolongs diastole. Acceleration follows stimulation
of the sympathetic, both the rapidity and the force of the

THE HEART AND CIRCULATION. Ill

beat being increased. When a person faints from a blow
in the abdomen, it is because the pneumogastric is
affected and inhibits the action of the heart. The work
of the heart is very dependent upon its nervous condition
and functional diseases of the heart are practically wholly
due to nervous derangement.

Heart Sounds. — Through the stethoscope two heart
sounds may be heard. They are known as the first and
second sounds. The first is a soft, rushing sound, stronger
and louder than the other, and is caused in part by the
contraction of the muscle itself when the blood is forced
out and in part by the closure of the auriculo-ventricular
valves. The second sound is shorter and sharper, a snap,
and is caused by the closure of the semilunar valves
when the contraction of the ventricles ceases and they
begin to refill. In certain diseased conditions, where
the edges of the valves are roughened, they do not snap
properly and the sound varies from the normal.

The Heart Beat. — The rate of the heart beat is propor-
tionate to the size of the person and increases in rapidity
as the size diminishes. If the ear is placed over the abdo-
men of a pregnant woman, the heart of the fetus can be
heard beating very rapidly. In prolonged labor it may
become more rapid or very faint and warn the doctor
that something should be clone. The usual rate of the
pulse in the fetus is 140 to 150 times a minute, though it
varies with size and sex. At birth it drops to 140 to 130;
for the first year it is 130 to 115; for the second year 115
to 105; for the third year 105 to 95; from the seventh to
the fourteenth years 80 to 90; from the fourteenth to the
twenty-first years 75 to 80; from twenty-one to sixty 60
to 75. In old age it rises a little and is 75 to 80. The rate
is higher in the average woman than in the average man
and increases with exercise, with increase of temperature,
and in high altitudes, where the atmospheric pressure is
less.

At each beat of the heart from four to six ounces of
blood are expelled into the plumonary artery and the

112 THE HEART AND CIRCULATION.

aorta, and in 22 or 23 beats all the blood in the body
passes through the heart. The power exerted by the
heart every minute in thus driving the blood upon its
course has been estimated as sufficient to raise its own
weight, three-quarters of a pound, the height of the
Washington monument or 150 meters; for the ventricles
have to force the blood into vessels already full.

Factors Affecting Circulation. — There are three main
factors in the circulation: 1. the systole, which gives the
blood its first impulse; 2. the peripheral resistance in the
capillaries, which serves to hold it in check, slowing the
circulation and doing away with its rhythmic character,
and 3. the elasticity of the walls of the arteries.

If a ligature is tied about an artery, there is a swelling
on the side toward the heart, while in the case of a vein,
the swelling is on the side away from the heart, that is,
the swelling is in either case on the side from which the
blood comes. When an artery is cut, however, the blood
comes out rhythmically in spurts, though from a cut vein
it oozes slowly and regularly. For the blood is pumped
out by the heart rhythmically and its rhythmic beating
against the walls of the artery is felt in the pulse, which
follows slightly after the beat of the heart itself. The
pulse is due to the fact that the vessels into which the
blood is forced are already full. This causes a local
dilation at the beginning of the artery which passes with
diminishing force along its entire length, the distention
being due to the fact that more force is needed to drive
the blood through the small arteries and capillaries
than to stretch the elastic walls of the aorta and the large
arteries. It is this elastic character of the arteries that
makes the blood flow constant, for otherwise the blood
would come intermittently in jets, as it is pumped from
the heart. The elastic walls of the vessels, however,
offer a certain resistance to the pumping of the fluid
through them and at the same time, by relaxing between
whiles, allow a certain amount of fluid to be retained in
them, so that they continue full and the flow is more or

THE HEART AND CIRCULATION. 113

less constant. The insufficient outlet also helps to make
the flow constant.

By the time the blood reaches the veins its rhythmic
character has been done away with, but though there are
no elastic walls in the veins, it still has force enough after
the slowing in the capillaries to return to the heart.
In this it is aided to a certain extent by the valves and
by the action of the skeletal muscles as they contract and
expand, especially in the arms and legs, where the blood
runs perpendicularly and there is a high column to be
supported There are also more veins than arteries, each
large artery having two large veins, the venae comites, to
help get the blood back to the heart, and the veins anas-
tomose freely. Thus, if the blood cannot get back by one
channel it does by another. In parts like the brain, where
it is very important that there should be no compression,
since any disturbance of circulation would lead to serious
results, the vessels are enclosed in thick walls, and in the
liver, through which all the blood passes and where com-
pression is sure to cause trouble, the veins are simply
caverns carved out in the organ and have no walls.
They lie open when the organ is opened. Varicose
veins are the result of valves giving way through inherited
weakness or disease so that others have an unduly large
weight to support.

The Pulse. — The pulse wave is characterized by a
quick rise and a slow fall, though this cannot ordinarily
be distinguished by the finger. In some slow fevers, how-
ever, the fall is very long and distinct ripples can be felt.
This is known as the dicrotic pulse. With age the
arterial walls grow stiffer and more rigid and less adapted
to their work. In certain cases of heart disease the heart
does not transmit all the beats to the pulse and to get the
true rate the heart must be listened to.

The rate at which the pulse wave travels varies with
the size of the artery and the force of the heart beat
but is about 15 to 20 feet a second. The flow is most
rapid in the arteries because they are nearest the heart,

114 THE HEART AND CIRCULATION.

where the pressure is greatest, and slowest in the capil-
laries, where the area is greatest, the sectional area of
the capillaries, known as the peripheral area because it
is farthest from the heart, being larger than that of the
large arteries. Thus rapidity of flow varies with pres-
sure and with area.

Blood Pressure. — Liquids, moreover, are incompres-
sible and exert pressure on the walls of the tubes through
which they pass. The amount of pressure depends
upon the inflow and outflow, increasing directly with the
inflow and inversely with the outflow, that is, the smaller
the outlet the greater the pressure, and vice versa. The
pressure is also greatest nearest to the inflow and grad-
ually decreases with distance until at the point of out-
flow there is practically no pressure. So, in the arteries
the blood pressure is greatest in the large vessels nearer
the heart and gradually decreases as they branch into
smaller and smaller vessels. In passing through the
capillaries, owing to their small size and resultant in-
creased friction, the blood meets with more resistance,
the peripheral resistance, and this resistance usually
regulates the pressure in the arteries. The greater
the peripheral resistance, as a rule, the greater the ar-
terial pressure. The pressure in the capillaries is very
slight and in the veins there is practically no pressure.
In fact, in the large veins near the heart the pressure
is negative and the blood is almost sucked into the
heart.

Pressure, then, is greatest in the arteries and least in
the veins, while the rate of flow is fastest in the arteries
— 300 to 500 millimeters a second — and slowest in the
capillaries — 75 millimeters a second — being a little
faster again in the veins — 200 millimeters a second.

Blood pressure is gauged by opening a vessel and in-
serting a manometer, the pressure being determined
by the height to which the mercury is raised. In man
the pressure in the arteries is 120 to 160 millimeters.
It is considerably heightened during inspiration by

THE HEART AND CIRCULATION. 115

the increased pressure of the lungs on the heart and
great vessels. In pericarditis the opposite is true.

When the blood pressure is high, the pulse is small and
travels fast, because the wall of the artery is already
highly stretched. Such a pulse is hard and incompress-
ible. A large pulse occurs where the heart is strong
and the pressure is low, owing to peripheral dilatation.
A low-pressure pulse is soft and compressible if the
heart beat is weak. A slow pulse is generally stronger
than a rapid one.

The nerve supply of the blood-vessels comes from the
spinal cord through the vasomotor nerves, which are
connected with the sympathetic system and are distrib-
uted to the smooth muscle fibers of the vessels. They
are of two classes, the vasoconstrictors, which diminish
the lumen of the vessels, and the vasodilators, which
increase the size of the vessels. By these nerves the
general tone of the arteries is kept up. They are dis-
tributed chiefly to vessels in the skin and in the abdom-
inal organs and the constrictors are probably the more
important. When the constrictors are stimulated,
three phenomena occur: 1. diminished flow through
the vessel, due to its diminished size; 2. increased gen-
eral arterial pressure, and 3. increased flow through
the other arteries. When the dilators are stimulated
the opposite effect is produced: 1. the flow through the
vessel is increased; 2. there is decreased arterial pres-
sure, and 3. there is decreased flow through the other
arteries. The palor of fright is due to the action of
the vasoconstrictor nerves of the face and blushing
to the action of the vasodilators. Heat stimulates
the vasodilators so that more blood goes to the skin,
perspiration begins, and the body is cooled by evapo-
ration. Cold stimulates the vasoconstrictors and the
blood is kept within the body, where it cannot cool.
If a part has too much blood, an impulse passes by
the vasoconstrictors to lessen the supply, while if
more blood is needed a message goes to the central ner-

116 THE HEART AND CIRCULATION.

vous system and an impulse passes by the vasodilators
to flush the organ. The more active a part is in func-
tioning the greater the number of capillaries, except
in the brain, which has only large vessels. The vessels
of the intestines contain much blood and are capable
of containing all the blood in the body.

The Blood. — The blood itself, which thus circulates
through the body, carrying nutrition to the tissues and
removing waste, is a complex fluid of a bright red color.
Its amount has been calculated to be about one-thir-
teenth of the body weight. One-fourth of it is gener-
ally in the heart, lungs, and large arteries and veins,
one-fourth in the liver, one-fourth in the skeletal mus-
cles, and one-fourth variously distributed through the
other organs. If there is too little blood, the vital pro-
cesses cannot go on as they should, while too great a
supply causes weakness rather than strength. So the
tendency is to keep the amount constant and any blood
added is disposed of and any blood lost is replaced. In
starvation it is the last tissue to be used up, for on it
the life of the other tissues depends.

Composition. — In composition the blood is practi-
cally the same in all arteries and fundamentally the same
everywhere, but in passing through certain organs cer-
tain substances are added to or taken from it, so that
its character changes more or less. Thus it varies some-
what in composition in different parts of the body, as
in the liver and kidneys. It has five main functions:
1. the conveying of fuel from the digestive tract to the
tissues, or force production; 2. the carrying of oxygen
to the tissues; 3. the carrying of tissue-building mate-
rials, or tissue building; 4. the distribution of heat; and
5. the removal of waste products.

The blood is slightly alkaline in reaction, of a saltish
taste, and has a specific gravity of 1^55. Its temper-
ature is about 100° Fahrenheit or 37.8° Centigrade. It
is made up of two parts, the plasma or fluid portion and
the corpuscles or solid portion. The plasma, again,

THE HEART AND CIRCULATION. 117

which is transparent and almost colorless, consists of
two materials, the blood serum and fibrin. Fibrin does
not exist as such in the body nor in freshly shed blood,
but there is a substance named fibrinogen which is worked
on by another substance, the fibrin ferment, to form
fibrin. Both fibrin ferment and fibrinogen can be iso-
lated from the blood.

Coagulability. — In the body the blood is perfectly
fluid and under normal conditions does not coagulate.
But, though fluid when first shed, upon standing it
gradually becomes viscid, that is, in two or three minutes,
then jelly-like, in five to ten minutes, and grows firmer
and firmer until there finally appears around this jelly-
like mass or clot a yellowish fluid, the serum. The
clot is made up of the corpuscles and fibrin. If some
blood is drawn and set on ice until the corpuscles settle,
the plasma can then be drawn off, and after it has stood
awhile in a warm place coagulation will take place, a mass
of fibrin forming in the middle. It takes from one to
two hours for clotting to be complete. In very slow
clotting at a low temperature the white corpuscles ap-
pear in a layer on top of the clot, the buffy coat.

Of fibrin little is known, but its formation is the
most important step in clotting, as its presence is ab-
solutely essential. If it is removed by whipping, the
blood will not clot. It is a delicate, stringy material,
elastic and contractile, and contains certain salts of lime
and magnesium, upon whose presence its power of coagu-
lation depends. The coagulability of blood differs in
different people and is occasionally so little as to make
operation dangerous.

The most favorable temperature for clotting is that
of the body, extreme heat preventing it and cold delaying
it. That the blood does not clot in the body must be due
to some relation between the blood and the walls of the
arteries and veins that prevents it, just as the walls of
the stomach are not digested by the juices secreted.
Though coagulation does not normally take place in the

118 THE HEART AND CIRCULATION.

body, it does take place when a blood-vessel is injured or
when the blood comes in contact with the air, a wise pro-
vision of nature, as otherwise the tendency would be for
bleeding to go on indefinitely after injury. The greater
the surface with which the blood comes in contact
the more quickly it clots. Injury to the vessel wall
itself is necessary; the endothelium must be cracked.
Under extreme injury the muscular coat of the vessel
undergoes spasmodic contraction and partially closes
it. Hence a wound caused by tearing is less likely to
bleed than one due to cutting.

The valves of the heart, which are covered with en-
dothelium, are frequently the seat of fibrin coagulation,
bits of the fibrin thus formed giving rise to conditions
in various kinds of heart trouble. Or the bits of fibrin
float in the blood and perhaps lodge in the small ves-
sels of the brain and cause apoplexy. Pus in various
parts of the body will set up coagulation in nearby
arteries. In fact, the presence of any foreign sub-
stance in the blood causes clotting.

FIG. 45. — Cells of blood: a, Colored blood-corpuscles seen on the flat; 6, on
edge; c, in rouleau; d, blood platelets. (Leroy.)

Blood-corpuscles. — The solid parts of the blood are the
red corpuscles, the white corpuscles, and the blood plaques
or plates. It is to the red corpuscles, or erythrocyles
which number about 5,000,000 to the cubic milli-
meter of blood, that the color of the blood is due.
Under the microscope they appear as small, spher-
ical, biconcave discs with a slightly greenish-yellow

THE HEART AND CIRCULATION. 119

color, which have a tendency to form in rouleaux.
They are homogeneous, with no limiting membrane,
and are made up of a fine network of tissue, the stroma,
in which is embedded the hemoglobin or coloring mat-
ter. This hemoglobin is a crystalline body and the
most complex substance known to chemists. The cor-
puscles are very flexible and can squeeze through small
apertures, as in the tiny capillaries, and regain their
shape. They are probably formed chiefly in the red
bone marrow at the ends of the bones, which under the
microscope shows red corpuscles in various stages of
growth, and also in the spleen, for which no other use
is known. Their function is to carry oxygen, which
forms a chemical combination, though an extremely
loose one, with the hemoglobin. As the tissues are
more greedy of oxygen than is the hemoglobin, they
rob the corpuscles of it.

FIG. 46. — Various forms of leucocytes: a, Small lymphocyte; 6, large lympho-
cyte; c, polymorphonuclear neutrophile; d, eosinophile. (Leroy.)

The white corpuscles or leucocytes are much fewer in
number, about one to from 300 to 700 of the red, the
average number being 5,000 to 10,000 to the cubic milli-
meter. They are larger than the red corpuscles, color-
less, and spherical when at rest. Their structure is more
definite, there .being a definite cell substance or proto-
plasm and one or more nuclei, which vary more or less
in shape and size. The corpuscles are classed in accord-
ance with these variations in the nuclei. They are
most numerous during digestion and are probably formed
in the lymphatic system, constantly passing from the
lymphatics to the arteries and veins. For they have

120 THE HEART AND CIRCULATION.

the function of amoeboid movement by which they not
only wander from place to place in the blood, keeping
close to the sides of the vessels, but pass through the
walls of the capillaries, probably between the cells
which form their lining, into the lymph spaces. This
is known as migration of the white corpuscles. In in-
flammation they collect in the inflamed area to assist
in allaying the inflammation by absorbing and carry-
ing off its products. Fof they carry waste products
and destroy poisons, acting as scaven^ rs and pro-
tectors of the body. When they are unsuccessful and
the inflammation gets the better of them, they become
pus corpuscles.

Besides the corpuscles there are seen floating in the
blood small disk-like substances with no special char-
acteristics, the blood plaques or plates, whose function
is unknown.

In anemia the red corpuscles are diminished and the
white corpuscles and blood plaques increased in number.
After excessive bleeding normal salt solution is in-
jected, subcutaneously or by rectum, as being nearly
equivalent to blood serum in composition, and the re-
newal of the solid elements is left to time. The length
of time needed for their restoration is about a week,
except in the case of the hemoglobin, which takes
longer.

CHAPTER IX.
THE LUNGS AND RESPIRATION.

Besides the heart and the great vessels the chest
contains the lungs, the chief organ of respiration, which,
with the rest of the respiratory system, will now be
treated. The nose and mouth, through which the air
first enters the body, have already been spoken of.
From them the air passes through the larynx to the
trachea, thence to the bronchi, and so to the lungs,
where the supply of oxygen for the tissues is taken from
the air by the hemoglobin, of the blood.

The Larynx. — The larynx lies in front of the pharynx
at the upper and fore part of the neck, where it causes
a considerable projection, k'lown as Adam's apple.
It is a triangular box, base up, flattened at the back,
in front, and at the sides, but becoming cylindrical be-
low. Above it opens into the bottom of the pharynx
and below into the trachea. It is lined with mucous
membrane. Its opening at the base of the tongue is
closed during swallowing by a little door-like valve of
fibre-cartilage, the epiglottis, to pre , ent the" entrance
of food.

Nine cartilages go to make up the larynx, of which
the most important are the thyroid and cricoid car-
tilages and the epiglottis already mentioned. The
thyroid is the largest and is open behind, its two alae
or wings meeting in an acute angle in front and forming
the Adam's apple, always more prominent in the male
than in the female. It is attached above to the hyoid
bone and has cornua or horns on either side, top and
bottom. The cricoid or ring-like cartilage resembles
a seal ring with the stone placed posteriorly. It is
stronger than the thyroid and forms the lower part of

121

122 THE LUNGS AND RESPIRATION.

the cavity of the larynx. Inside and resting on the
upper border of the cricoid are the two smaller arytenoid
or pitcher-like cartilages, pyramidal in shape, and sur-
mounting these again the two cornicula laryngis. The
two cuneiform cartilages are in the free borders of the
folds of mucous membrane which extend from the apex
of the arytenoids to the sides of the epiglottis. Numer-
ous small muscles serve to bind these various cartilages
together.

At the angle of the thyroid cartilage in front are at-
tached the epiglottis at the top and just below that the
superior or false vocal cords, two folds of mucous mem-
brane enclosing the superior thyro-arytenoid ligaments.
Lower still are found the inferior or true vocal cords,
which are formed by the inferior thyro-arytenoid lig-
aments covered with a thin, tightly fitting mucous mem-
brane. Both sets of vocal cords as well as the epiglot-
tis may be seen by means of a head and a throat mir-
ror. Between the true vocal cords is a narrow tri-
angular interval called the glottis. It is by means of the
vibrations of these cords that sound is produced. The
false vocal cords cannot produce sound, though they
can modify it indirectly. Quality of voice, as treble,
base, etc., depends upon the size of the larynx and the
length and elasticity of the vocal cords. Modulation
is produced by changing the form of the cavity of the
mouth and nose. In whispering the lips take the
place of the vocal cords and produce sound by the
vibration of their muscular walls.

Instead of tracheotomy laryngotomy is sometimes
done in the depression between the thyroid and the
cricoid, which may be felt on the living. Foreign bodies
sometimes get into the larynx and have to be removed,
or the mucous membrane may become inflamed, caus-
ing laryngitis. Syphilis attacks the larynx, and tuber-
culosis and cancer of the larynx occur, these last two
being generally fatal. Edema of the glottis may also
occur.

THE LUNGS AND RESPIRATION.

123

The Trachea. — The trachea is a membranous tube ex-
tending down from the larynx for about four and a
half inches to the fourth or fifth dorsal vertebra, where
it divides into the right and left bronchi. It is formed
of sixteen to twenty imperfect cartilaginous rings,
open behind, enclosed in a double elastic fibrous

FIG. 47. — The larynx, trachea and bronchi. (After Sobotta.)

membrane, and is lined with ciliated mucous mem-
brane. The rings are for strength and in the interval
at the back where they are wanting there is one layer
of longitudinal and another of transverse unstriped
muscle fibers. The passage is kept clear by the action
of the cilia, which sweep up and out any particles of
dust that become entangled in the mucus. Trache-
otomy is generally done about one inch below the cri-

124

THE LUNGS AND RESPIRATION.

coid, just above the sternal notch, incision being made
through the cartilage.

Extending up on either side of the upper trachea in
the neck are the two lobes of the thyroid gland, the
isthmus, which connects the lobes, covering the trachea
below anteriorly. The function of the gland is ob-
scure, but it has an internal secretion of great im-
portance in the metabolic processes. Its removal or

Thyreoict cartilage

Thyreoliyoiileus
Right common carotid artery

Right internal jugular vei,

Scalentti anterior

Cricothyreoideus

Fio. 48. — The upper thorax of a child eight years old, 'showing the thyroid and
thymus glands. (Sobotta.)

disease is followed by general disturbances of mind and
body. The injection of thyroid extract has proved
effective as treatment. In goiter the gland becomes
enlarged. The thymus gland lies below the thyroid
gland at birth, in front of and at the sides of the trachea,
and runs down behind the sternum. It is largest at
the end of the second year, after which it atrophies,
being almost absent at puberty. It, too, is ductless and
its function is not well understood.

THE LUNGS AND RESPIRATION.

125

The Bronchi. — The two bronchi, of which the right is
the larger and shorter, resemble the trachea in struc-
ture. As they enter the root of the lung they divide,
the right into three and the left into two branches, one
for each lobe, after which they divide and subdivide,
the bronchioles becoming smaller and smaller and finally
ending in the infundibula, pouch-like places lined with
air cells, in which cilia keep the air in motion. As they
grow smaller the bronchioles gradually become wholly
membranous.

The Lungs. — The lungs themselves, two in number,
lie each in a serous sac or pleura, similar in structure

Right common

carotid artery.

Subclavian

arteries .

Innominate
artery.

Arch of aorta
Right lung.

Superior vena

cava.
Right auricle.

Larynx.

Trachea.
Subclavian
arteries.

Pulmonary
artery.

FIG. 49. — Relation of lungs to other thoracic organs. (Ingals.)

to the pericardium and serving a like purpose. The
outer layer of the pleura is reflected back over the tho-
racic wall and 'diaphragm. There is no pleural cavity
in health between the two layers of the pleura, the two
surfaces being in close contact, though moistened with
lymph to prevent friction during respiration. In in-

126 THE LUNGS AND RESPIRATION.

flammation of the pleurae or pleurisy, they become thick-
ened and roughened and friction results, as is shown
by the sounds heard through the stethoscope. Fric-
tion causes effusion and fluid collects. This generally
absorbs again, but occasionally the serous fluid becomes
pustular and empyema results.

In front, between the two pleurae, which are wholly
separate, is the mediastinal space or mediastinum, which
extends from the sternum to the spinal column and con-
tains all the thoracic viscera except the lungs and heart,
that is, the trachea, esophagus, thoracic duct, and many
large vessels and nerves.

FIG. 50. — Diagrammatic representation of the termination of a bronchial
tube in a group of infundibular B, Bronchial tube; LB, bronchiole; A, atrium;
/, infundibulum; C, alveoli, (de Nancrede.)

Roughly speaking, the lungs begin at the sterno-
clavicular articulation above, the apex coming up above
the level of the first rib, and extend downward together
to the fourth cartilage, where the lower margins gradu-
ally separate, the lowest lung limit being the eleventh
rib in the vertebral region. Each lung is conical. The
apices extend upward and the bases, which are broad
and concave, rest upon the diaphragm. The right lung
is divided by a fissure into three lobes, the left into
two. The root consists of a bronchus and pulmonary
arteries, veins, lymphatics, and nerves. The tissue
itself is composed of an aggregation of lobules, each
consisting of a terminal bronchiole with its alveoli or
air cells, blood-vessels, and nerves, a lung in miniature.

THE LUNGS AND RESPIRATION. 127

The blind pouches which the air cells surround are
called infundibula and are separated by delicate mem-
branous septa in which lie the capillaries of the pulmo-
nary artery, thus exposing the blood to the air on two
sides. The lung itself is supplied by the bronchial
arteries from the thoracic aorta and by branches of the
sympathetic and pneumogastric nerves.

At birth the lungs are pinkish-white in color but in
later life they are marked with slate-colored patches,
due to the deposit in the lung tissue of particles of dirt
breathed in. They are light, spongy, and highly elas-
tic, and will float in water, crepitating upon pressure
owing to the air in the tissue.

At birth, also, the lungs are solid, so that the first
air has to overcome adhesions between the collapsed
walls of the bronchioles and air sacs, but after they
are thus gradually unfolded, in that they are of exten-
sible material and open to the air above, atmospheric
pressure from within keeps them distended to the full
extent of the chest, which is air tight. They never col-
lapse afterwards unless puncture of the chest wall, as
in stabbing, causes collapse, in which case the lung
shrivels into a small ball.

Respiration. — That the organic materials used by the
body as food may give up their energy they must be
broken up, and for this oxygen is needed. The supply
of oxygen for the purpose is brought to the tissues by
the blood, which acquires it in the lungs, and the waste
product of combustion, carbon dioxide, is carried off
in the same manner. The lungs are, therefore, adapted
to take in large quantities of air and to keep up a rapid
exchange of oxygen and carbon dioxide in the blood.
This process of supplying oxygen to the tissues and
of removing carbon dioxide and other waste is ordi-
narily an involuntary act, though it can be regulated
temporarily, and is known as respiration or breathing.

There are two periods to respiration; 1. inspira-
tion or the drawing in of air, and 2. expiration or the

128 THE LUNGS AND RESPIRATION.

expulsion of air from the lungs, the former process being
a little shorter than the latter. A pause follows each
expiration before there is another inspiration. At
birth the normal rate of respiration is 42, but it grows
slower as the child grows older, being 26 at the age of
five or six, while in the adult it averages 17 to 20 times
a minute. It is slower during sleep and more rapid
during physical activity. The average amount of air
taken in with every inspiration is 30 cubic inches and
the minimum air space per individual should be 3000
cubic feet per hour.

Breathing is of two kinds, diaphragmatic or abdom-
inal and chest or rib breathing, the former usually being
more pronounced in men than in women, probably be-
cause of centuries of tight dressing on the part of the
latter. As a rule, however, both diaphragm and ribs
come into play; for in inspiration, which is an active
movement, the thorax becomes enlarged from before
backward, laterally, and vertically. The ribs are raised
by the external intercostals chiefly, though the internal
intercostals aid somewhat, and swinging out upon the
vertebrae, widen the chest as well as deepen it. The
diaphragm, which is dome-like when relaxed, becomes
flattened in contraction and so increases the size of
the chest from above downward. As the chest enlarges,
the lungs expand, the air in them becomes rarefied, and
more air rushes in. When the lungs are full they re-
lax and the muscles relax after their contraction, so that
expiration is a passive movement, due largely to the
elastic relaxation of lungs and muscles, the air being
driven out by the lessened capacity of the lungs.

Difficult Breathing. — In heart and lung troubles,
where too little oxygen is carried to the tissues, dys-
pnoea or difficult breathing results and may even ad-
vance to asphyxia, a condition in which no air is ob-
tained. In difficult or labored respiration the pectoral
muscles are used in inspiration and the scaleni, which
pass from the vertebrae of the neck to the sternum,

THE LUNGS AND RESPIRATION. 129

develop and become powerful. The levatores of the
ribs may also assist, and even the muscles of the neck
and arms may help out, while in forced expiration the
abdominal muscles are called into play. The glot-
tis opens and closes rhythmically as the air enters and
leaves the lungs, and the nostrils add their mite in the
struggle for oxygen. Finally there may be scarcely
a muscle in the body that is not striving to aid the res-
piration, and general convulsions may result, followed
by exhaustion and death.

Air. — In ordinary breathing the lungs are not used
to their full capacity and the air ordinarily used is
known as tidal air. In forced inspiration the lungs
are filled to their fullest extent and the air then taken
in in excess of the tidal air is known as complemen-
ted air. In like manner, the difference between the
air ordinarily breathed out and that breathed out
in forced expiration is known as supplemental air.
The sum of these three is the vital capacity of the
lungs, while beyond this there is probably some air
that is never expelled, the stationary or residual air.

Respiratory Sounds. — The entrance and exit of the
air is accompanied by respiratory sounds or murmurs,
which vary according to their position in the trachea,
the bronchi, or the bronchioles and are modified in
diseases of the lungs and bronchi, when they are
often called rales.

Changes in Air in Lungs. — In passing through the
nose and the rest of the respiratory tract the air is
warmed to body temperature and saturated with
moisture. After its entrance into the lungs various
changes take place in it through the mingling of the
tidal with the residual air. Thus, it gives up about 4 or
5 per cent, of its oxygen and acquires some 4 per cent,
additional carbon dioxide, while the amount of nitro-
gen remains about the same. By its giving up more
oxygen than it receives carbon dioxide, its volume
is slightly diminished. Exhaled air also contains

130 THE LUNGS AND RESPIRATION.

traces of ammonia and certain organic matters, gen-
erally the results of decomposition, which give a bad
odor to the breath and are more dangerous in a close
room than the mere lack of oxygen or the presence of
carbon dioxide. Indeed, the amount of oxygen may
be very much diminished, being reduced even to 5 or
6 per cent, instead of the normal 21 per cent., without
being noticed or giving rise to any immediate bad re-
sults. Yet the import? nee of ventilation is very
evident.

Effect on Blood. — Respiration causes changes also in
the blood, the venous blood being purple and the ar-
terial bright red. This difference in color is due to the
absence or presence of oxygen, which is not absorbed
or dissolved by the blood but forms a rather unstable
compound, oxy hemoglobin, with the hemoglobin of
the blood. As the oxgen is removed in the passage
of the blood through the body, there results in venous
blood reduced hemoglobin, which is of a purplish
color. Upon exposure to the air, however, it absorbs
oxygen once more and resumes its scarlet color. If
carbon monoxide gets into the blood, as in cases of
gas poisoning, it drives off the oxygen and forms a
more stable compound with the hemoglobin, whence
the difficulty in restoring a person so poisoned.

Nervous Mechanism. — Nervously, respiration is con-
trolled in three ways: 1. by the phrenic nerve to
the diaphragm; 2. by some fibers of the vagus or
pneumogastric, and 3. by the respiratory center in the
bulbous portion of the spinal cord. Injury to the res-
piratory center means the ceasing of respiration and
death. Stimulation of the respiratory center seems
to depend upon the character of the blood. If it is
well oxygenized, the breathing is slow and quiet; if
there is a lack of oxygen, dyspnoea results. Probably
certain chemical substances in the blood, which are
ordinarily rapidly burned up by the oxygen but which
accumulate in its absence, serve to stimulate the

THE LUNGS AND RESPIRATION. 131

respiratory center, thus adjusting the effort to get oxy-
gen to the need of it. Respiration may be stopped
by stimulating the mucous membrane of the nose, as
with strong ammonia.

Variations. — Certain variations from the ordinary
respiration might be mentioned here. A deep inspira-
tion followed by a long expiration is known as a sigh
and a very deep inspiration through the mouth only as
a yawn. Hiccough results from a sudden inspiratory con-
traction of the diaphragm during which the glottis is
suddenly closed. In sobbing the inspirations are short
and rapid with a prompt closing of the glottis be-
tween. Both coughing and sneezing consist of a deep
inspiration followed by complete closure of the glot-
tis and then its sudden opening and the forcible ex-
pulsion of air. Coughing, however, is generally caused
by an irritation or obstruction of the larynx or trachea
and the air is expelled through the mouth, while sneez-
ing is caused by irritation of the nasal passages and the
air is driven out through the nose. Laughing and
crying also resemble one another in that each is an in-
spiration followed by a series of short, spasmodic ex-
pirations, during which the glottis is open and the
vocal cords in characteristic vibration. They differ,
however, in rhythm and in the facial expression that
accompanies them.

CHAPTER X.

THE ABDOMEN AND THE ORGANS OF
DIGESTION AND EXCRETION.

The Abdominal Cavity. — Below the diaphragm and
separated from the lowest cavity of the trunk, the
pelvis, only by an invisible plane drawn through the
brim of. the true pelvis, is the abdominal cavity, which
may be said in a general way to contain the organs
of digestion and the kidneys. It is protected behind
by the vertebrae and anteriorly by the lower ribs above
and below by muscular walls, which make possible the
complete bending of the body. These muscles are
for the most part large and very strong and the greater
number are inserted, in part at least, into a median
tendinous line, the linea alba, which passes from the
ensiform cartilage of the sternum above to the sym-
physis pubis below.

Muscles. — The external obligue muscles form the outer-
most layer of the abdominal wall. They rise from
the external surface of the eight lower ribs on either
side and are inserted in the anterior half of the iliac
crest as well as by aponeurosis in the linea alba, where
each joins its fellow from the opposite side, the fibers
running downward and inward like the fingers in the
trouser's pocket. Along the lower border of the apo-
neurosis is a broad fold, Poupart's ligament. The in-
ternal oblique rises on either side from the outer half
of Poupart's ligament and the anterior part of the crest
of the ilium and is inserted into the crest of the os pubis,
the cartilages of the lower ribs, and the linea alba.
Its fibers run at right angles to those of the external
oblique. These oblique muscles serve to compress the
viscera, to flex the body, and also assist in expiration.

132

THE ABDOMEN.

133

The deepest of the abdominal muscles is the trans-
versalis, which rises from the outer third of Poupart's
ligament and the adjoining part of the crest of the
ilium, from the six lower costal cartilages, and by a

FIG. 51. — Muscles of the trunk from before (left side, superficial; and right
side, deep): 1, Pectoralis major; 2, deltoid; 3, portion of latissimus dorsi; 4,
serratus magnus; 5, subclavius; 6, the pectoralis, sternocostal portion; 7, serratus
magnus; 12, rectus abdominis; 13, internal oblique; 14, external oblique; 15,
abdominal aponeurosis and tendinous intersections of rectus abdominis; 16, over
symphysis pubis; 17, linea semilunaris; 18, gluteus medius; 19, tensor vaginse
femqris; 20, rectus- femoris; 21, sartorius; 22, femoral part of iliopsoas; 23,
pectineus; 24, adductor longus; 25, gracilis. (Borland's Dictionary.)

broad aponeurosis, the lumbar fascia, from the lumbar
vertebrae. It is inserted into the pubic crest and by
aponeurosis into the linea alba. There is one of these
muscles on either side.

The rectus abdominis is also really two muscles and

134 THE ABDOMEN.

extends from the symphysis pubis to the cartilages
of the fifth, sixth, and seventh ribs. At first it passes
back of the oblique and transversalis muscles, but about
a fourth of the way up it passes in front of the trans-
versalis and between two layers of the internal oblique,
which thereafter forms its sheath. Its chief duty is to
flex the chest on the pelvis, though it also compresses
the abdominal viscera.

One other muscle, a small one, is found in front, the
pyramidalis , which rises from the pubic crest and is in-
serted into the linea alba midway to the umbilicus.

At the back the open space over the kidneys, between
the lower ribs and the os innominatum, is closed in on
either side by the quadratus lumborum, which extends
from the three or four lower lumbar vertebrae and the
adjacent iliac crest to the last rib and the upper four
lumbar vertebrae. It flexes the trunk laterally or forward
according as one muscle or both are used, and may aid
in either expiration or inspiration.

The nerves of the abdominal muscles are chiefly the
internal intercostals.

The Peritoneum. — Lining the abdominal cavity is a
serous membrane, the peritoneum, which is reflected
back over the viscera within in such a way as to cover
each one wholly or in part. Folds of peritoneum, the
omenta, connect the stomach with the other viscera, the
most important being the great omentum, which has one
layer descending from the anterior and another from the
posterior wall of the stomach. The mesenteries are
double layers of peritoneum which hold the intestines
to the vertebrae and posterior wall. Between their folds
run the blood-vessels.

Abdominal Regions. — For convenience of description
the abdominal cavity has been divided into nine regions
by means of two transverse paralled lines, the one through
the ninth costal cartilages and the other just over the
iliac crests, and two perpendicular parallel lines through
the cartilage of the eighth rib and the middle of Poupart's

THE ABDOMEN. 135

ligament on either side. These nine regions have been
named as follows: The right and left hypochondriac
regions up under the ribs with the epigastrium between,
the right and left lumbar regions next below with the
umbilical between, and the right and left inguinal with

FIG. 52. — Diagram showing the nine regions of the abdominal cavity:
1, Right hypochondriac; 2, epigastric; 3, left hypochondriac; 4, right
lumbar; 5, umbilical; 6, left lumbar; 7, right iliac; 8, hypogastric; 9, left
iliac. (Ashton.)

the hypogastric between. Others divide it into quad-
rants by one line drawn across and another down through
the umbilicus. The contents of the abdomen in full are
the stomach, intestines, liver, gall-bladder, spleen, pan-
creas, kidneys, suprarenal capsules, and the great vessels,
that is, the organs of digestion and excretion. When dis-

136 THE ABDOMEN.

tended the bladder extends up into the abdominal cav-
ity, as does the uterus also when enlarged.

Salivary Digestion. — Although most of the digestive or-
gans are situated in the abdomen, the food enters the body
through the mouth, where its prehension is a voluntary
act. Here digestion also begins and from the first the
process is a double one, mechanical and chemical, me-
chanical digestion consisting largely of muscular move-
ments by which the food is ground up and carried through
the digestive tract. Thorough mastication or grinding
of the food by the teeth is necessary, while the tongue
assists by moving the food about and by mixing it
thoroughly with the saliva, a viscid fluid composed of
water and salts and having a slightly alkaline reaction.
The saliva is secreted by the parotid, sublingual, and
submaxillary glands, and serves to soften and dissolve the
food and by virtue of its unorganized ferment, ptyalin, to
convert starch into sugar. Upon proteins and fats it has
practically no digestive action. Moderate warmth and
an alkaline medium favor its action, while extremes of
heat or cold or an acid medium hinder it. There is little
absorption in the mouth, though starch, nicotine, and
alcohol may be absorbed in small quantities.

The Pharynx. — When the food is ready for deglutition
or swallowing, it is thrust back into the pharynx, a some-
what conical, musculo-membranous sac, situated, base
upward, behind the nose and mouth and behind, but
somewhat above, the larynx. The pharynx is about four
and a half inches long and ends on a level with the
cricoid cartilage in the esophagus or gullet. It is at-
tached to the vertebrae at the back and opens in front
into the mouth. The posterior nares, the Eustachian
tubes, and the larynx also open into it, the last being pro-
tected by the epiglottis, which closes during deglutition
to prevent food from entering the air passages, just as
the soft palate is drawn back to prevent regurgitation of
food into the nose. There are three coats to the
pharynx; 1. a mucous coat continuous with that of the

THE ABDOMEN.

137

mouth and ciliated down to the floor of the nares; 2. a
fibrous coat, and 3. a muscular coat containing among
others the constrictor muscles which serve to carry the
food down to the esophagus. Its arteries are branches

FIG. 53.— Position of the thoracic and abdominal organs, front view
(Morrow.)

of the external carotid and its nerves come from the
spinal accessory and the sympathetic. Occasionally a
foreign body gets lodged in the pharynx just out of reach
of the finger and threatens strangulation. Retropharyn-
geal abscess on the posterior wall occurs rarely.

138 THE ABDOMEN.

The Esophagus. — From the pharynx the food passes to
the cardiac orifice of the stomach, opposite the tenth
dorsal vertebra, through the esophagus, a muscular tube
about nine inches long, which collapses when empty, its
lumen then appearing as a transverse slit. It, too, has
three coats: 1. an inner mucous coat; 2. an areolar coat,
and 3. a muscular coat, the muscles being arranged in two
sets, an outer longitudinal layer and an inner circular
layer. By a series of ryhthmic contractions, especially
of the circular fibers, the food is pushed along, though
sometimes with liquid food there is no peristaltic action
of the esophagus, the pharyngeal muscles alone sending
it to the stomach. At the lower end of the esophagus an
especially strong band of circular muscle fibers form a
sort of sphincter, which prevents the regurgitation of
food. The whole act of swallowing is a reflex, not a
voluntary, act and is due to irritation set up by the
stimulus of the foreign body, the food. Stricture of the
esophagus is common and may be of three kinds: 1. spas-
modic, occurring in nervous women; 2. fibrous, due to
scar tissue, or 3. malignant, due to cancer.

The Stomach. — The stomach is a pear-shaped dilata-
tion of the alimentary canal, lying under the liver and
diaphragm in the epigastrium and left hypochondrium
and connecting the esophagus with the small intestine.
It lies largely behind the ribs, but the greater curvature
is only two fingers' breadth above the umbilicus and can
be manipulated through the skin. The cardiac end, into
which the esophagus enters, is the larger and points
upward to the left. The lesser and lower end, known as
the pylorus, is at the right and its opening into the small
intestine is guarded by the pyloric sphincter. The lesser
curvature is concave and on the upper surface; the greater,
convex and on the under surface. The great omentum
is attached to the latter.

In size the stomach varies more or less, that of a man
generally being larger than that of a woman, but it is
usually about ten inches long and four or five inches

THE ABDOMEN. 139

across. It has a capacity of about five pints and serves
as a storehouse for food.

The stomach has four coats: 1. a serous coat derived
from the peritoneum; 2. a muscular coat of three layers
with longitudinal fibers continuous with those of the
esophagus, circular fibers, and oblique fibers; 3. an areolar
coat, and 4. a mucous coat, which, when the stomach is
empty, is thrown into longitudinal folds or rugce, and
whose surface is covered with glands, the gastric glands,
for the secretion of the digestive fluids.

The arteries come from the celiac axis and the nerves
from the pneumogastric and the solar plexus.

Ulcer and cancer of the stomach are both rather com-
mon. In the former there is apt to be hyper-acidity and
in the latter %jw>-acidity, but the rule does not always
hold. In cases of ulcer there may be hemorrhage and
even perforation. Such hemorrhage can be distinguished
from hemorrhage from the lungs by its slightly acid odor
and by the frothy character of hemorrhage from the
lungs. There is much irritation at the pylorus and where
there is irritation there is liable to be cancer.

Gastric Digestion. — In the stomach the food is churned
and thoroughly mixed with the gastric juices, and it is
also subjected to a propulsive movement that drives it on
to the intestine. When it comes to the stomach it is semi-
solid and when it has become fluid or semi-fluid, in which
state it is known as chyme, it is ready to pass on. Before
it can do so, however, it must overcome the strong pyloric
sphincter, and this it does by the muscles about the
sphincter pushing it constantly on until the sphincter
gives way. Probably most of the propulsive movements
take place within a few inches of the pylorus.

The gastric juice is secreted by glands in the wall of the
stomach and poured out through little tubules which
project from the surface. It is a thin, almost colorless
fluid with a sour taste and odor due to the presence of free
hydrochloric acid, an important element in digestion.
Probably when the stomach is empty and for some twenty

140 THE A&DOMEN.

minutes after the appearance of food there is no hydro-
chloric acid present and, the food being alkaline, salivary
digestion continues. Then, called forth by the presence
of the food, the hydrochloric acid appears and salivary
digestion ceases in the acid medium. Little digestion
of starches or fats takes place, the chief action being on
proteins, which are converted into soluble peptones.
For besides hydrochloric acid the gastric juice contains
two ferments: 1. pepsin, which is particularly active in
aiding the digestion of proteins, and 2. rennin, which
especially affects milk. Neither hydrochloric acid nor
pepsin seems capable of digesting food alone, but each
is essential to the other. They are secreted by different
types of cells, secretion depending upon the nerve supply
and upon the presence of food. Gastric digestion is
favored by minute subdivision of the food and by the
right proportion of hydrochloric acid, which should be
0.2 per cent. Body temperature is also advantageous.
Except that proteins are put in solution and partly di-
gested, little digestion goes on in the stomach, and though
the rugae afford a large absorbing surface, little absorption
takes place, although more takes place than in the mouth
and in time most foods, except fats, can be absorbed.
The time of digestion varies with different foods and in
different poeple, but probably three to five hours are
necessary. The food leaves the stomach as chyme, a
fluid of about the consistency of pea soup.

Vomiting is more or less the reverse of swallowing and
is generally preceded by a feeling of nausea, which starts
up retching, a more or less involuntary effort of the stom-
ach to throw off its contents. To relieve the retching a
long breath is taken, followed by a deep expiration that
opens the cardiac end of the stomach and allows the
abdominal muscles to force the food out. After much
vomiting and prolonged retching the pyloric end of the
stomach may be affected and bile will then appear in the
vomitus. Artificial vomiting may be produced by irrita-

THE ABDOMEN. 141

tion of the gastric nerve center in the brain or by irrita-
tion of the stomach itself.

Intestinal Canal. — From the stomach the food passes
into the intestinal canal, a convoluted tube which extends
from the stomach to the anus and in which, more partic-
ularly in the upper portion, the greater part of the diges-

FIG. 54. — The intestinal canal: 1, Stomach; 2, duodenum; 3, jejunum; 4,
ileum; 5, cecum; 6, vermiform appendix; 7, ascending colon; 8, transverse
colon; 9, descending colon; 10, sigmoid flexure; 11, rectum. (Leidy.)

tion and absorption of food takes place. This tube,
which is about six times the height of its possessor, con-
sists of two parts, the small and the large intestines, the
first four-fifths, or about 25 feet, being small intestine.
It occupies the central and lower parts of the abdominal
cavity and a small portion of the pelvic cavity, and is
attached to the spine by the mesentery, which, however,

142 THE ABDOMEN.

allows great freedom of motion, so that there is little
fixation to the loops of the small intestines.

The Small Intestine. — The small intestine opens out of
the stomach and has three divisions: 1. the duodenum,
which is only about ten to twelve inches long; 2. the jeju-
num, so called because it is generally empty after death,
which is about two-fifths of the remainder and lies chiefly
in the umbilical region and the left iliac fossa, and 3. the
ileum or curved intsstine, the remaining three-fifths, which
gets its name from its numerous coils and which lies in
the middle and the right side of the abdomen. There is
no direct division between the jejunum and the ileum, but
the first part of the former and the last part of the latter
are quite different in character. At its entrance into the
large intestine the ileum is guarded by the ileo-cecal
valve.

The same coats continue in the small intestine as were
found in the stomach, but they are here much thinner and
the inner coat is shaggy, like velvet, with innumerable
minute processes called mlli, which greatly
increase the absorbing surface. In fact,
the great length of the intestine as well as
the presence of the villi is aimed to pro-
vide a large surface to absorb the food as
it passes, an even greater increase of sur-
face being provided by the fact that the
tr^i10' licteai-' °e2 intestinal wall is thrown into folds, the
capillary network! valvulce conniventes. Each villus is covered

3, columnar cells. . ., , r> i «ji T i n i

with a layer of columnar epithelial cells and
has within connective tissue, in which are found a fine
capillary network and open lymph spaces from which
leads a single lacteal vessel.

Closely connected with the lymphatic vessels are the
solitary glands, small round bodies the size of a small pin's
head. Peyer's glands or patches are patches of solitary
glands opposite the mesenteric attachment and are
largest and most numerous in the ileum. In typhoid
fever they are involved and may become the seat of

THE ABDOMEN. 143

ulcers. There are also the glands of Lieberkiihn which
secrete the succus entericus.

The arteries of the small intestine, which include the
superior mesenteric, are from the celiac axis and the
nerves are from the superior mesenteric plexus of the
sympathetic. The veins empty chiefly into the portal
system.

The movements of the intestine, like those of the
esophagus, are peristaltic, but the action is complicated
by the fact that the tube is not straight but in coils.

Intestinal Digestion. — The food, which enters the duo-
denum as chyme, there comes in contact with the bile and
the pancreatic juice, which together but unmixed enter the
duodenum from their respective ducts by a common orifice.
As in the stomach, the digestive juices are called forth by
the presence of food. The bile is secreted in the liver, from
which it flows away through the hepatic duct, which joins
the cystic duct from the gall-bladder to form the common
bile duct. Through this it flows into the intestine during
digestion, but between whiles it passes up into the gall-
bladder, where it is stored for future use and whence it is
expelled when needed. When pure it is a thick, viscid
liquid, varying from a bright red to a greenish-yellow in
color according to the pigments present, and of an alka-
line reaction. It consists chiefly of the bile pigments,
biliverdin, which gives the green color, and bilirubinf
which gives the red color, and of bile salts in solution.
cholesterin, which probably forms the basis of many gall
stones, is also present. Bile is a disinfectant to the bowel
and a lubricant for the feces. How much digestive
action it has is a question, but it affords the necessary
alkaline medium for the pancreatic juice to act in.

The pancreatic juice is secreted by the pancreas, from
which it enters the intestine through the pancreatic duct,
and is probably the most important fluid in the digestive
process. It is clear, practically colorless, slightly viscid
or gelatinous, and quite strongly alkaline in reaction,
owing to the presence of sodium carbonate. It contains

144 THE ABDOMEN.

three ferments, amylopsin for the digestion of starch,
trypsin for the digestion of proteins, and steapsin for tho
digestion of fats. By it, as by the saliva, starch is turned
into sugar or maltose, in which form it is absorbed, while
proteins are converted into peptones, as they are in the
stomach. Since, however, fats are acted on nowhere else,
the chief function of the pancreatic juice may be con-
sidered to be the digestion of fats. Having broken
through their albuminous envelope, it divides them into
glycerine and fatty acids and then emulsifies them with
the assistance of the bile.

The food also comes in contact with the succus enteri-
cus, a juice secreted by the glands of Lieberkiihn in the
small intestine, whose chief action is the conversion of
sugar into glucose.

Absorption. — As the food is absorbed from the intes-
tine it is liquid and entirely digested and is known as
chyle. Practically all absorption takes place from the
small intestine, though there is a little in the large in-
testine. It takes place in two ways: 1. through the por-
tal vessels and 2. through the lacteals, which are the
lymphatic vessels of the small intestine. Fats are ab-
sorbed practically entirely by the lacteals. They enter
the cells covering the villi, travel thence to the lymph
spaces, and so into the lacteal or main lymph channel,
whence they are carried to the thoracic duct and the
general circulation. From the blood they are absorbed
as fat and stored up as adipose or fatty tissue, which is
found throughout the body in connective tissue about
the organs. Organic salts and water are for the most
part absorbed by the portal system, which they reach
through the capillaries of the villi and through which
they go to the liver. Starches, in the form of sugar,
pass between the cells of the villi into the lymph spaces,
from which they are taken up by the capillaries. On the
way to the liver maltose becomes dextrose. Proteins,
in the form of peptones, pass through the layer of
epithelial cells to the lymph spaces and then to the

THE ABDOMEN. 145

capillaries, an active part being taken by the cells. By
the time they reach the liver the peptones have been
changed back into proteins. In fact, peptones seem to
have some poisonous effect upon the blood if they get
into it as such.

The Large Intestine. — The large intestine differs from
the small in size and in fixity of position, lying curved in
horseshoe shape above and around the small intestine.
It is five or six feet long, large in caliber, and is thrown
into crosswise folds. It has the same four coats as the
small intestine, but the mucous coat is pale and smooth,
without villi. Its glands are the crypts of Lieberkiihn
and the solitary glands. The arteries are branches of the
superior and inferior mesenteric and the nerves come
from sympathetic plexuses.

The blind sac lying in the right iliac fossa, with which
the large intestine begins, is called the cecum, and into
this the ileum opens, the ileo-cecal valve preventing
regurgitation. Just below the ileo-cecal opening is the
vermiform appendix, a narrow, worm-like tube with a
blind end, varying in length from one to nine inches, but
generally about four and one-half inches long, which, so
far as is known, is functionless as well as dangerous.
People have been born without an appendix and it has
in rare instances grown again after operation. Its base
is located in the living by McBurney's point, a point two
inches from the anterior superior spine of the ilium on
a line drawn from the spine to the umbilicus.

From the cecum the intestine ascends in what is known
as the ascending colon along the abdominal wall at the
right to the under surface of the liver, where it turns
in the hepatic flexure abruptly across the body to the
left, passing below the liver, stomach, and spleen in
the transverse colon. In the splenic flexure it turns down
the left abdominal wall, the descending colon passing to
the crest of the ilium, where there is another curve,
the sigmoid flexure, leading to the rectum, which passes
for six or eight inches down along the vertebrae, a little
10

146 THE ABDOMEN.

to the left, to the anus, the external opening. This
opening is guarded by two sphincter muscles, about an
inch apart, the internal and external sphincters. The
coils of the small intestine lie below the transverse colon,
covered mostly by the omentum. The splenic flexure is
behind the stomach and below the spleen and is slightly
higher than the hepatic flexure. The sigmoid flexure
can be felt in the left inguinal region in thin people.

The fact that the rectum is somewhat to the left is of
importance in childbirth because if the rectum is packed,
it may turn the child's head in the wrong direction.

No digestion goes on in the large intestine, the func-
tion being to dry by absorbing water. The movements
are practically the same as those of the small intestine
except that they are much less active. Fermentation
makes the contents acid. By the time food reaches the
rectum it has been thoroughly digested and has given up
its nourishment. It is then expelled as waste matter or
feces. Defecation combines the involuntary movements
of peristalsis and relaxation of the sphincters with the
voluntary aid of the abdominal muscles. The ano-spinal
reflex, by which movements of the bowel are regulated,
is in the lumbar enlargement of the cord.

The hemorrhoidal veins in the lower rectum are con-
nected with both the systemic and the portal veins and
have no valves so that, as they are subjected to much
strain, they often become varicose and dilated. This
condition is called hemorrhoids or piles. Obstruction of
the intestine may be caused by the growth of a con-
stricting band, by intussusception or telescoping of the
intestine on itself, especially at the ileocecal valve, or by
volvulus or twisting. Foreign bodies are sometimes found
in the appendix but they are not usually the cause of
appendicitis. Cancer of the intestine is common and its
mass is apt to cause obstruction with all its attendant
symptoms. It may necessitate an artificial anus.
Hernia or rupture may also occur and the hernia may
become strangulated.

THE ABDOMEN. 147

Food and Metabolism. — Anything serves as food that
replaces or hinders the loss to which the component parts
of the body are liable. Proteins, carbohydrates, fats,
some mineral matters, as salt and perhaps iron, and water
are needed. The energy once expended by plants or
animals in the formation of the materials which serve as
food is set free in the body by the breaking up of these
complex substances into their original elements, which
are then recombined into the complex materials needed
for the body's life and growth. This process of building
up complex materials from simple ones is known as
anabolism and that of breaking them down as katabolism,
while the two combined form the complete cycle of
metabolism. Those foods have the best value that give
up their energy most readily. For their combustion,
heat, oxygen, and water are needed. Hunger indicates
that the supply of material for katabolism has been used
up and that more is needed, just as thirst indicates the
need of the system for more fluids.

The proteins or nitrogenous foods include all animal
foods except fats, fish, crustaceans, eggs, milk and its
products, certain vegetables, especially the lentils, that
is, peas and beans, and gelatine. The fats include various
fats and oils commonly eaten. The carbohydrates are
the starchy foods, as cereals, sugars, fruits, and most
vegetables, in fact, practically all except the lentils.
Various beverages and condiments have no great nutri-
tive value but serve to stimulate the appetite and to
excite the secretion of the digestive juices. Coffee, tea,
and alcohol are stimulants.

The different classes of foods have different functions
in the nourishment of the body. The proteins are pri-
marily tissue-builders and also help somewhat in force
production. The fats are essentially heat-producers,
though they too help in force-production. The carbo-
hydrates are chiefly important as force-producers,
though they also produce heat and to a certain extent
save protein oxidation. Fat is formed by all three but

148 THE ABDOMEN.

only in small amount by proteins. So no one food can
form the whole diet but there must be. variety. Carbo-
hydrates and fats are not sufficient for life, some protein
is necessary. Carbohydrates are more digestible than
fats but have less potential energy. Gelatine saves waste
of nitrogen, though it does not increase the supply.
Water and salts are not nutritive but they aid the body
processes, the water helping to dilute and dissolve
substances for digestion.

The end-product of the consumption of protein is
urea, which is eliminated by the kidneys. Just where it
is formed is unknown, but many think in the liver. A
trifling amount of urea is also eliminated in the sweat and
in the breath as well as in the feces. Proteins increase
nitrogenous metabolism and also the metabolism of
other foods, but the amount of nitrogen eliminated is just
equal to that taken in. Probably some comes from the
tissues themselves and not from the food. The oxida-
tion of carbohydrates and fats is measured by the amount
of carbon excreted. At first as much is given off as is
taken in, but after a while the carbohydrate is stored up
as glycogen in the liver and the fats are stored as fat.

The amount of food needed varies with the person's
size and occupation, less being needed for a child than for
an adult and more for a hard-working man than for one
who is doing less work. In general, 100 to 130 grams of
protein, 40 to 80 grams of fat, 450 to 550 grams of carbo-
hydrates, 30 grams of salts, and 28,000 grams of water
is a fair amount.

Foods are cooked to make them more digestible and to
develop their flavor, so that they will taste better. Cook-
ing also kills germs and parasites that might be harmful.
Meats should be cooked rapidly on the outside to coagu-
late the surface albumen and keep in the juices. The
heat, besides coagulating the albumen, turns the tough
parts to gelatine. In cereals the tough envelope of
cellulose is broken up and in vegetables the tough fibrous
parts are softened and made more digestible.

THE ABDOMEN. 149

The Liver. — Below the diaphragm on the right and
extending across above the stomach, resting in a way
upon the transverse colon and the small intestine, is the
liver, the largest gland in the body. It is dark reddish-
brown in color and is larger in proportion in the child than
in the adult. The upper surface is convex and lies in
contact with the diaphragm, while the lower surface is
concave to fit over the organs beneath. With a full

FIG. 56. — The liver, seen from below. 1, Inferior vena cava; 2, gall-bladder.

(Morrow.)

breath it comes downward and forward, with the edge
against the abdominal wall, and can be easily felt.
Numerous strong ligaments, including the suspensory
ligament from the diaphragm, hold it in place, and it is
more firmly fixed than any other of the abdominal organs,
probably on account of its large size. It is divided by
fissures into five lobes, of which the most important are
the right and left, the right one being the largest and con-
taining the gall-bladder in one of its fissures.

The liver tissue contains a large number of cells collected

150 THE ABDOMEN.

into lobules, in the center of each of which is a blood-
vessel, the intralobular vein, from which a network of
capillaries extends to the edge of the lobule, there being
a capillary on either side of each row of cells. Between
the cells also are the intercellular biliary passages, roots of
the bile ducts which exist in the connective tissue between
the lobules and which join to form two main ducts, one
from the right and the other from the left lobe. By the
union of these two ducts the hepatic duct is formed, which,
after a course of one or two inches, joins the cystic duct
from the gall-bladder to form the ductus communis or
common bile duct.

The liver has a double blood supply, the hepatic artery
from the celiac axis bringing nourishment to the connect-
ive tissue and the walls of the blood-vessels, while the
capillaries between the cells come from the portal vein,
which, being formed by the junction of the superior and
inferior mesenteric, the splenic and the gastric veins,
contains the proteins and carbohydrates absorbed during
digestion. After its passage through the liver this blood
from the portal vein is collected once more into the
hepatic veins, which convey it to the inferior vena cava.
During its passage, however, various changes take place,
for the liver plays an important part in the metabolic
processes of the body.

The liver has two principal functions, the secreting of
bile and the storing up of glycogen. The secretion of
bile, which is a very important aid to digestion, is prob-
ably a reflex act, the presence of peptones in the portal
blood after meals acting as a stimulant to the liver cells.
For food at once increases the secretion of bile, which is
poured from the cells into the small bile ducts and finally
passes into the hepatic duct and so to the gall-bladder,
where it is stored until needed. Although the flow from
the liver is constant, the .amount secreted reaches its
maximum when the food gets down into the small in-
testine, that is, four or five hours after eating, there being
a lull before that. Apart from the process of secretion,

THE ABDOMEN. 151

the manufacture of the bile pigments, bilirubin and bili-
verdin, which are made from the hemoglobin of the
blood, seems to require some special action on the part of
the liver cells.

The glycogen, which is manufactured and stored in the
liver cells, is a clear hyaline substance, akin to starch and
capable of being converted into sugar by the starch fer-
ment. Probably there is some such ferment in the blood
which converts the glycogen into sugar as soon as it passes
from the liver into the blood, though what it is, is not
known. Neither is it known just how glycogen is formed,
but it is manufactured chiefly after a mixed meal in which
carbohydrates predominate, proteins having little and
fats no effect upon its formation. It is undoubtedly
formed from the sugar in the portal blood and the pro-
cess requires some work on the part of the liver cell itself.
Probably there is always some sugar in the circulating
blood which, as it is used up, must be made good. If
there it not enough in the diet, the liver supplies the
deficiency from its store of glycogen.

Glycogen is found also in the muscles, in the placenta
as food for the fetus, in leucocytes, and to a slight extent
in cartilage. In fact, it is the form in which carbohydrate
material is supplied to the tissues as needed. Normally,
much of the sugar is used up by the blood and its cells in
metabolism, giving rise to heat and energy. In muscles
glycogen is probably digested as lactic acid, as before
action muscle is neutral or slightly alkaline and after
action acid.

When the liver is deranged and allows the glycogen to
pass out into the blood too freely, or when the glycogen is
not held as such but turned to sugar and passed out in
large quantities, sugar in the urine or diabetes mellitus
results.

Besides its secreting function the liver has an elimina-
tive function and plays an important part in purifying the
blood, removing from it many poisonous and narcotic
substances. It is thought by some, though it has not

152 THE ABDOMEN.

been proved, that urea, the end-product of protein
metabolism, which is brought by the blood to the kidneys
and there excreted, is formed in the liver. At any rate,
urea is formed not only from the nitrogenous food eaten
but from the metabolism of protein substances in the
tissues, being purely a waste product, from which the
nutritious substances have been absorbed. The amount
thrown off is an accurate gauge of the amount of protein
metabolism going on. The process of its manufacture
is doubtless very complex.

Ptosis or dropping of the liver sometimes occurs and is
due to the stretching of the ligaments. Rupture is
common, generally as the result of a fall from a height,
on account of its size and friability. The liver is also
subject to many diseases. Cirrhosis occurs in people
who drink a good deal and in its later stages is accom-
panied by ascites, an accumulation of fluid in the ab-
dominal cavity. When there is a general accumulation of
fluid throughout the body it is known as anasarca.
Syphilis causes enlargement of the liver. Abscesses
occur, perhaps oftener in the tropics than farther
north, and may break into the lungs, stomach, or
intestine.

The Gall-bladder. — The gall-bladder, which is simply
a reservoir for the bile, is a pear-shaped organ three inches
long and one inch broad. It lies in a fossa on the under
side of the liver, with the large end or fundus touching
the abdominal wall just below the ninth costal cartilage.
Here it can be felt as a small mass in empyema of the
gall-bladder. Normally it holds a little over one ounce,
but with occlusion it may become stretched. Its duct
is the cystic duct, which joins the hepatic duct in the
common bile duct, but bile only passes up into the gall-
bladder when the opening into the duodenum is closed,
that is, between meals.

If one of the bile ducts is stopped up by a stone or
cancer or for any other cause, the bile backs up in the
liver, the pigments are absorbed into the circulation,

THE ABDOMEN.

153

and jaundice results. In this condition operation is
dangerous, as the time of coagulation of the blood, nor-
mally five minutes or less, is much delayed. Gall-stones,
formed largely of bile pigments and cholesterin, some-
times collect in the gall-bladder, where they cause irrita-
tion and may give rise to empyema of the gall-bladder.
The stones vary in size from a pea to a hen's egg and
when small may be very numerous.

The Pancreas. — Another accessory organ of diges-
tion is the pancreas, the abdominal salivary gland, as

Head of Tc

FIG. 57. — The pancreas, spleen, gall-bladder, etc., showing their relations.
(After Sobotta.)

it is sometimes called on account of its close resem-
blance to the parotid gland. This is a grayish-white
racemose gland, six and a half inches long by one and
a half inches wide and one inch thick, lying behind
the stomach on a level with the first and second lumbar
vertebrae and shaped like a pistol with its handle toward
the right. In an emaciated person it can be felt. The

154 THE ABDOMEN.

pancreatic duct runs the whole length of the gland from
left to right and conveys the pancreatic juice from vari-
ous little glands in the substance of the organ to the
duodenum, into which it empties along with the com-
mon bile duct by a common orifice. The arteries are
from the celiac axis and superior mesenteric, the veins
belong to the portal system, and the nerves come from
the solar plexus.

Surgically the pancreas is of no special importance,
though acute pancreatitis does occasionally occur and
is a very serious condition and one hard to diagnose.

The Spleen. — The largest and most important of
the ductless glands is the spleen, an oblong, flattened
organ lying deep in the left hypochondriac region be-
tween the stomach and diaphragm above the descend-
ing colon, and corresponding to the ninth, tenth, and
eleventh ribs. It is soft, brittle, and very vascular. Its
artery is a branch of the celiac axis and the vein belongs
to the portal system. Its nerves are the pneumogas-
tric and branches from the solar plexus. The function
is not well understood but probably it is connected
with or related to the vascular system in some way.
Perhaps it manufactures blood corpuscles.

The spleen varies more in size than any other organ.
Normally it cannot be felt, but in typhoid it usually
can. It is generally atrophied in old age and hyper-
trophied in almost all acute infectious diseases, especi-
ally in typhoid fever and malaria. In leukemia it is
often greatly enlarged. Sometimes in violent falls it
is ruptured and there is considerable hemorrhage.

The Suprarenal Capsules. — The other ductless glands,
the suprarenal capsules, yellowish triangular bodies,
are situated just above and in front of the kidneys.
Their function is important but not well understood.
Death, accompanied by great muscular weakness, follows
the removal of both, and when they are diseased, similar
weakness is observed and the skin becomes bronzed.
Injection of the extract of the suprarenals stimulates

THE ABDOMEN.

155

the muscular system. So probably they secrete into the
blood minute quantities of a substance or substances
beneficial to the body, especially to the muscular system.
The Kidneys. — The two kidneys lie on either side of
the vertebrae at the back of the abdominal cavity and
behind the peritoneum, between the last dorsal and
the third lumbar vertebrae, their inner edge being about
one inch from the spinous processes. They are bean-
shaped, four inches long, two inches wide, and one inch

FIG. 58. — Diagram of the relation of kidney to viscera, spine, and surface
points. (American Text- Book of Surgery.)

thick, and are embedded in a mass of fat and loose areolar
tissue. They can be felt only when misplaced or when
enlarged, as by tuberculosis or malignant disease.

The whole kidney is enveloped in a fibrous capsule
which normally may be peeled off but which in some
diseases becomes adherent. On the internal border is
a fissure or hilum, through which pass the blood ves-
sels and the ureter. Upon entering, the ureter dilates
into a sac, the pelvis of the kidney, into which project
the Malpighian pyramids of the medullary substancef
a substance made up of the straight uriniferous tubules

156

THE ABDOMEN.

and blood-vessels. Outside the medullary substance
and just under the capsule is the cortex, containing
the Malpighian bodies, blood-vessels, and the con-
voluted tubules or loops of Henle. Each Malpighian
body contains within a capsule a plexus of capillaries,
the glomerulus} with an afferent arteriole and an effer-
ent vein. The renal artery is a branch of the aorta and
the nerves are from the solar plexus.

Fie. 59. — A longitudinal section of FIG. 60. — A Malpighian body or

the kidney. (Leroy.) a, Renal ar- corpuscle. (Leidy.) a, Afferent
tery; c, cortex; TO, medulla; u, ureter. artery; e, efferent vessel; c, capil-
laries; k, commencement of urinif-
erous tubule; h, uriniferous tubule.

The Urine. — As the blood passes through the glom-
eruli, the urine is filtered off as it were, probably by
a process of transudation rather than simple filtration.
The cells lining the tubules also play an important
part in its formation, not by secreting new substances
but by taking up those brought by the blood and dis-
charging them into the convoluted tubules, from which
the urine passes through the straight tubules of the
medulla to the pelvis, to be carried thence by the ure-
ter. The process of the formation of the urine, there-

THE ABDOMEN. 157

fore, is not purely a process of secretion but requires
some action on the part of the kidney, though no new
substances are secreted in the kidney.

The passage of the urine down through the ureters
is assisted by a kind of peristaltic action in the walls
of the ureters and it is expelled from the body by the
act of micturition, which is mostly voluntary, though
a certain amount of nervous mechanism controls it.
The seat of this nervous mechanism is in the lum-
bar enlargement of the spinal cord. In some nervous
conditions, especially where there is injury to the spinal
cord, there is involuntary micturition.

The urine is a watery solution containing many waste
products, especially urea. It is generally amber in
color, varying in shade with circumstances, with an
aromatic, characteristic odor when fresh. It is acid
in reaction and has a specific gravity of about 1020,
though this too varies with circumstances. Besides
water, which is its chief constituent, it contains urea,
uric acid, organic acids, urates, inorganic salts, includ-
ing sodium chloride and phosphates of calcium and
magnesium, a certain amount of ammonia, and certain
pigments. Its acidity is due to acid sodium phosphate
in solution but varies with the food, and in disease the
urine may become alkaline when passed. After stand-
ing a few hours in a warm place it decomposes and be-
comes alkaline.

The quantity, which is normally three pints or fif-
teen hundred cubic centimeters in twenty-four hours,
varies with the amount of fluid drunk, the amount of
perspiration, etc. The amount secreted depends chiefly,
however, upon the flow of the blood through the kidneys;
the greater the flow of blood, the larger the amount of
urine formed; and the blood flow is determined by blood
pressure and by vasomotor action. Secretion also seems
to be increased by the presence of urea, which apparently
serves as a stimulant to the kidney cells.

The excretion of waste materials takes place by three

158 THE ABDOMEN.

main channels, the lungs, skin, and kidneys, and the
materials are of four kinds, urea, carbon dioxide, salts,
and water. The lungs carry off carbon dioxide and
water chiefly, the skin these and inorganic salts, while
the kidneys eliminate practically all the urea as well
as inorganic salts and water. When the kidneys are
not working the skin carries off much urea. In fact,
a close relationship exists between the kidneys and the
skin in the matter of excretion. Thus, with increased
perspiration in warm weather comes decreased urine,
while in cold weather the blood is sent in and the
urine increased in amount.

To incite action of the kidneys drugs known as
diuretics may be used. These act in two ways, by stim-
ulating the kidney cells directly and by acting on the
general circulation or nervous system. Any emo-
tional or nervous excitement increases the flow of
urine.

There are certain abnormal constituents of urine,
of which the two most important are albumen and
sugar. The former is found only when there is some
disturbance of the kidneys, ureters, or bladder, and its
presence usually denotes some change in the cells lining
the urinary tract. It may occur in congestion of the
kidney as well as in disease. Sugar is found only in dia-
betes, the amount varying with the severity of the dis-
ease. In jaundice certain bile pigments are present in
the urine, giving it a dark brown color and to the foam
a greenish-yellow color. Even normal urine has some
sediment upon standing, consisting of cells from the
urinary tract and mucus. In very acid urine after
standing a heavy sediment, whitish or pinkish, i.e., brick
dust, in color, is thrown down. It does not necessar-
ily denote disease, but shows the urine is acid and con-
centrated. In alkaline urine there is a sediment due
to phosphates.

Rupture of the kidney occurs but is not so serious as
rupture of the liver or spleen because the kidney is sit-

THE ABDOMEN.

159

uated outside of the peritoneum. It necessitates the
removal of the kidney, however, and when for any rea-
son one kidney is removed the other increases in size
and does double work to compensate for the loss. Re-
moval of both kidneys means death. Sometimes the
kidney becomes loose and moves about, a condition
known as floating kidney. Perinephritic abscess is ab-
scess in the loose fatty tissue about the kidney.

The Ureters, one for each kidney, are tubes the size
of a goose quill and about fourteen inches long, extend-
ing from the hilum of the kidney to the base of the blad-

iJnev

'thro.
FIG. 61. — The urinary organs viewed from behind.

der. They have three coats, an internal mucous, a
muscular, and an external fibrous coat, this last being
continous with the cortex of the kidney and the fibrous
tissue of the bladder. In the female the ureters may
be felt through the wall of the vagina as they come into
the bladder. In tubercular disease of one kidney the
ureter becomes inflamed and enlarged and through the
vagina feels almost like a lead pencil, a sure diagnostic
sign.

The Bladder and Urethra. — In their course to the
bladder the ureters pass from the abdominal into the

160 THE ABDOMEN.

pelvic cavity, but before describing the pelvis itself it
will be well to complete the account of the urinary or-
gans by considering the bladder and urethra. The
bladder is the reservoir for the urine and has muscular
walls lined with mucous membrane. A peritoneal coat
covers the upper surface and is reflected to the walls of
the abdomen and pelvis. It is situated back of the os
pubis, the front bone of the pelvis, with its base or
fundus directed downward and backward. Normally it
is in the pelvis, but when much distended it mounds up
into the abdominal cavity, where it can be felt in front
as a tumor. It rests on the rectum in the male and on
the cervix in the female and is held in place by numer-
ous ligaments. When empty it may be Y-shaped, but
it becomes oval when distended. Its capacity is about
one pint.

The lower abdominal wall and the anterior wall of
the bladder may be wanting congenitally. In paralysis
of the sphincter at the neck of the bladder distention
results. Stones may be found in the bladder.

From the neck of the bladder the urine passes out of
the body through the urethra. This in the male passes
down through the. penis and is about ten inches long.
Except when urine is passing it is a transverse slit with
the upper and under surfaces in contact, while at the
end of the penis the slit of the meatus urinarius is vertical.
When the penis is flaccid, the urethra describes a sharp
curve before its entrance into the bladder, but it be-
comes approximately straight when the penis is raised
at right angles to the body — an important point to re-
member in catheterization.

In the female the urethra is straight and much shorter,
being only about one and a half inches long. The
meatus urinarius is in the anterior vaginal wall about
one inch behind the clitoris.

Sometimes the urethra is ruptured in a fall. Strict-
ure of the urethra occurs sometimes after gonorrhoea,
owing to the formation of scar tissue following ulcer.

CHAPTER XI.
THE PELVIS AND THE GENITAL ORGANS.

The Pelvis. — Before taking up the pelvic organs, the
pelvis itself should be described. The name pelvis has
been given to the bony ring which is interposed between
the spine and the femurs on account of its resemblance
to a basin. At the back of this basin or pelvis are the
sacrum and coccyx, already described in connection with

FIG. 62. — Front view of the pelvis, with its ligaments. (Borland.) a, Anter-
ior sacro-iliac ligament; 6, iliofemoral ligament; c, obturator membrane ;d, sym-
physis pub is; e, sacroseiatic ligament.

the back, and at the sides and meeting in the median
line in front are the two ossa innominata or nameless
bones, so called on account of their peculiar and inde-
scribable shape. At birth each os innominatum is made
up of three bones, the ilium, ischium, and pubes, but
about the age of puberty the three become welded into
11 161

162

THE PELVIS AND THE GENITAL ORGANS.

one. At their point of junction is the cavity of the
acetabulum for articulation with the head of the femur
or thigh bone.

The upper, expanded portion of the os innominatum
is the ilium, whose upper border is known as the crest
and which has two spinous processes front and back, a
superior and an inferior, the superior spine being in each

Crest of ilium.

Anterior gluteal line.

Ala of ilium. ^ .J^^jjjj jj|!j |i ?,y •&£? "- Anterior superior spine.

ill

Iliac portion.

Semilunar

surface.

Acetabular fossa

Cotyloid notch. -
Ischiatic portion.

Tuberosity of ischium. —

-" Iliopectineal eminence.

Pubic portion.

-Spine of pubes.

Ramus of pubes.

Obturator foramen. Ramus of ischium.

FIG. 63.— The right innominate bone. (After Toldt.)

case the larger. These spines, especially the anterior
superior spines, and the crest give attachment to many
muscles, and to the outer surface of the bone the glu-
teal muscles are attached. The anterior superior spine
is also important in making measurements to ascer-
tain whether both legs are of equal length.

Below the ilium posteriorly is the body of the isch-

THE PELVIS AND THE GENITAL ORGANS. 163

ium, which has on its lower edge a tuberosity, the promi-
nent bone on which one sits. Near the upper edge
is the spine of the ischium, between which and the pos-
terior inferior spine of the ilium is the greater sacro-sciatic
notch for the passage of vessels and nerves, including
the sciatic nerves. From the tuberosity the ramus ex-
tends forward below the obturator foramen, a large open-
ing between the ischium and the pubes, also for the
passage of vessels and nerves, to meet the pubes, the
last and smallest of the three bones which go to make
up the os innominatum.

The anterior surface of each pubes presents a crest,
ending externally in a spine, and the two pubic bones
join in front in the symphysis pubis. The bone gets
its name from the growth of pubic hairs over this region
at puberty.

FIG. 64.— Diameters of the pelvis: d, antero-pos tenor; ob, oblique;
t r, transverse, (de Nancrede.) '

Anteriorly the ossa innominata support the external
organs of generation, while within are the internal or-
gans of generation. On the inner surface of the ilium,
slightly above the level of the acetabulum, is the ileo-
pectineal line, above which lie the iliac fossce. A plane
drawn through the prominence of the sacrum, the ileo-
pectineal lines, and the upper margin of the symphysis
pubis serves to divide the upper or false pelvis from
the lower or true pelvis. The false pelvis, which is
the larger, serves to support the intestines and to

164 THE PELVIS AND THE GENITAL ORGANS.

take part of the weight from the abdominal walls,
while the true pelvis, being more surrounded by
bone and so capable of affording more protection,
guards the internal organs of generation. The lower
circumference of the pelvis is known as the outlet. In
the female the bones are lighter, the sacrum less curved,
and the diameters greater than in the male.

On the whole, the pelvic bones are well covered in with
muscles. The anterior superior spine, however, is easily
felt in front and the whole crest can be felt back to the
posterior superior spine. The tuberosity of the ischium
also can be felt, especially when the thigh is flexed,
for it is largely uncovered of muscles. The spine of
the os pubis can always be felt, on a level with the great
trochanter, and the relation of its position to that of
a hernia shows whether the rupture is above or below
Poupart's ligament, that is, whether it is inguinal or
femoral.

Occasionally there is lack of development of the pubic
bones for two or three inches and the bladder is exposed.
Fracture of the pelvis may occur, perhaps with injury
to the viscera. The acetabulum may be fractured
or the sacrum broken, with injury to the sacral plexus
of nerves, causing paralysis of the lower extremities
and of the sphincters, with resultant involuntary pas-
sage of urine and feces, and in childbirth the coccyx
is often broken. In rickets there may be great deform-
ity of the pelvis, causing trouble in childbirth later in
life. Osteomalacia is a disease of adults, in which the
bones are soft and the weight pushes the promontory
of the sacrum forward and approximates the sides of
the pelvis.

The Male Generative Organs. — The male generative
organs consist of the prostate gland, testes, and penis.

The prostate gland is shaped like a small horse-chest-
nut and is composed of numerous glands from which
come a dozen or more excretory ducts. It surrounds
the neck of the bladder and the beginning of the urethra

THE PELVIS AND THE_GENITAL ORGANS. 165

and is next to the rectum, through which an examina-
tion may be made to determine its size. For it
often enlarges in elderly men, the frequent passage of
urine in small amounts being a symptom of enlarged
prostate.

The procreating glands, which secrete the spermatozoa
or semen, are two in number, the testes or testicles, and
are homologous to the ovaries in the female. They are
ovoid in form and are suspended by the spermatic cords
in a sac, the scrotum, back of the penis. During early
fetal life they are in the back of the abdomen near the
kidneys, but before birth they descend along the in-
guinal canals into the scrotum. The excretory duct
of the testis is called the vas deferens. It passes up by
the spermatic cord through the inguinal canal into the
pelvis to the base of the bladder and at the base of the
prostate joins the duct of the vesicula seminalis to
form the ejaculatory duct. The two vesiculce seminales
are small receptacles for the semen lying in contact with
the base of the bladder and secrete a fluid with which
they dilute the semen. The ejaculatory duct terminates
near the prostate in the urethra by a slit-like orifice on
each side, the spermatozoa being finally excreted through
the urethra.

The penis is the external organ of generation in the
male and is attached to the pubes and the anterior part
of the ischium. It is composed of erectile tissue and
encloses the urethra, the meatus urinarius appearing
at its end as a vertical slit. Toward the end the skin
of the penis is loose and is prolonged forward in what
is known as the prepuce or foreskin. It is this that is
clipped away in circumcision.

The Female Generative Organs. — The female genera-
tive organs include the ovaries, Fallopian tubes, uterus,
vagina, and the external genitalia or vulva.

The ovaries, which are homologous to the testes in
the male, are two flattened oval bodies, grayish pink
in color, suspended from the lateral or broad ligaments

166 THE PELVIS AND THE GENITAL ORGANS.

which fasten the uterus to the walls of the pelvis. They
are one and a quarter inches long, three quarters of
an inch wide, and half an inch thick and are attached at
the upper end to one of the fimbrise of the Fallopian
tubes. They consist of numerous Graafian follicles em-
bedded in a fibrous stroma, each follicle containing an
ovum about TJT inch in diameter and just visible to the
naked eye. When a follicle ruptures and discharges an

FIG. 65. — View of the pelvis and its organs. (Savage.) B, Bladder; U, uterus
(drawn down by loop e); F, Fallopian tubes; O, ovaries; L, round ligaments;
g, ureter; a, ovarian vessels, often prominent under their peritoneal covering; R,
rectum; V, vertebra.

ovum, an irregular yellow spot, the corpus luteum, ap-
pears at the point of rupture. After ordinary menstru-
ation it is known as the false corpus luteum and after
conception as thejrue one, this one being larger and last-
ing longer.

The Fallopian tubes are the oviducts and convey
the ova from the ovaries to the uterus. They are four
inches long and lie between the layers of the broad
ligaments, opening into the uterus by an orifice the
size of a bristle, while the end next to the ovary spreads

THE PELVIS AND THE GENITAL ORGANS.

167

out trumpet-like and is edged with fimbrioe as with a
fringe, the fimbriated extremity. There are three
coats: a serous coat which is continuous with the perito-
neum, a muscular coat, and, within, a mucous coat
covered with cilia, continuous with the mucous mem-
brane of the uterus. One fimbria is attached to the

FIG. 66. — Sagittal section of the female pelvis. (Dickinson.)

ovary and as the ovum is given off it finds its way into
the tube and thence to the uterus.

The uterus is a pear-shaped organ, about three inches
long, two inches broad above, and one inch thick, situated
in the pelvic cavity between the rectum and the bladder.
The wide part or fundus is above and the narrow

168 THE PELVIS AND THE GENITAL ORGANS.

neck or cervix below, lying partly within the vagina.
The whole is held in place by ligaments. These in-
clude the broad ligaments, which extend from the sides of
the uterus to the lateral walls of the pelvis, and the
round ligaments, two muscular cords, about four inches
long, which pass out through the abdominal ring into
the inguinal canal and so to the mons veneris and labia,
thus corresponding to the spermatic cords in the male.
The cavity of the body of the uterus is small and
flattened and opens into the cervix by the internal os
uteri, the external os being at the opening of the cervix
into the vagina. There are three coats: a serous coat
derived from the peritoneum, a muscular coat of un-
striped fibers which forms the bulk of the whole organ,
and a mucous coat covered with ciliated epithelium.

The uterus is always enlarged during menstruation
and is enormously enlarged in pregnancy. It receives
the fecundated ovum, retains and supports it during
the development of the fetus, and is the chief agent of
expulsion. In tubal or extra-uterine pregnancy the ovum
becomes attached in the tube instead of in the uterus,
and develops there, rupturing the tube and causing
serious hemorrhage.

The passage from the cervix out of the body is the
vagina, a membranous canal, curved upward and back-
ward to conform to the axis of the pelvis, and attached
above to the cervix. Ordinarily the sides are in con-
tact.

The arteries of the internal organs of generation are
the uterine from the internal iliac and the ovarian from
the aorta in the female, the pudic branches of the in-
ternal iliac and the spermatic from the aorta in the
male. The nerves are largely from the sympathetic
system.

Abscess formation occurs frequently in the tubes and
gonorrheal infection may spread up the vagina and
through the uterus to the tubes, and even to the ab-
dominal cavity itself, The tubes may also be tubercular,

THE PELVIS AND THE GENITAL ORGANS.

169

Salpingectomy or removal of the tubes is the commonest
operation after that for appendicitis. Cancer of the
uterus may necessitate panhystercctomy or removal of
the uterus and all its appendages.

The external genitalia in the female, as in the male,
are situated over the pubic arch. They are known as

FIG. 67. — Virginal vulva. (Modified from Tarnief.) 1, labia majora; 2,
fourchet; 3, labia minora; 4, glans clitoridis; 5, meatus urinarius; 6, vestibule; 7.
entrance to the vagina; 8, hymen; 9, orifice of Bartholin's gland; 10, anterior
commissure of labia majora; 11, anus; 12, blind recess; 13, fossa navicularis;
14, body of clitoris.

the vulva and include the mons Veneris, the labia ma-
jora and minora, the vaginal orifice, the clitoris, and the
meatus urinarius.

The mons Veneris is a rounded eminence composed
of fatty tissue, which surmounts the pubic bones and
is covered with hair at puberty. From it two promi-
nent longitudinal folds of skin, covered with hair on
the outside, the labia majora, extend backward, form-

170 THE PELVIS AND THE GENITAL ORGANS.

ing the lateral boundaries of the vulva. Within these
labia again are two thin cutaneous folds, the labia minora
or nymph(K, which run back from the clitoris for about
one and a half inches and enclose the vaginal orifice.
The clitoris corresponds to the penis and is just above
the upper part of the labia minora. Between it and the
vagina is the meatus urinarius. The orifice of the vagina
is partly closed in the virgin by the hymen, a thin fold of
mucous membrane, which occasionally closes it com-
pletely, imperforate hymen. The fourchette is a small trans-
verse fold of skin at the junction of the labia minora
posteriorly. Between the vagina and the rectum is the
perineal body, a somewhat triangular structure made up
of many small muscles. Its surface is known as the peri-
neum. It is frequently torn wholly or in part during
childbirth and has to be sewed up.

CHAPTER XII.
THE UPPER EXTREMITIES.

The upper extremities include the shoulders, arms,
forearms, wrists, and hands and contain each thirty-
two bones. The bones of the two shoulders taken to-
gether are called the shoulder girdle and consist of the
two clavicles or collar bones and the two scapulae or shoul-
der blades, which together make an almost complete
girdle of the shoulders.

The clavicle is a long slender bone extending almost
horizontally from the sternum to the scapula and can
be felt for its whole length in the living. For the inner
two-thirds it is convex anteriorly, for the outer third
concave. In woman it is generally less curved, smoother,
and more slender than in man, and as bone is rough
when the muscles attached are powerful, the right clav-
icle, being used more, is generally rougher and thicker
than the left. Among the muscles attached are the
large neck muscle, the sterno-cleido-mastoid, whose
tendons form the presternal notch, the trapezius, the
pectoralis major, and the deltoid.

Being slender and superficial the clavicle is most
frequently broken of any bone in the body, generally
by indirect violence, as by falling with the hand out,
though old people in such a case are apt to get Colles'
fracture at the wrist. The bone generally gives way
at the juncture of the outer and middle thirds, with
displacement of the parts inward, so that the fracture
is seldom compound. Since, however, the main ves-
sels of the upper arm, with their nerves, lie beneath the
clavicle, there is danger of their being punctured. Such
serious injury is guarded against by the presence of

171

172

THE TIPPER EXTREMITIES.

Humerus-

Radius.
Interosseous space..

Scapula.

Pronator quadratus.

Carpus.
Metacarpus.

^".~5? Phalanges.

FIG. 68.— Bones of the upper extremity. (Toldt.)

THE UPPER EXTREMITIES.

173

the subclavius muscle. The clavicle is occasionally re-
moved for sarcoma.

The scapula or shoulder blade, so called from its shape,
is a large, flat, triangular bone with a prominent ridge,
the spine, crossing its dorsum or posterior surface near its
upper edge. It extends from the second to the seventh rib,
with its posterior margin parallel to and about one inch
from the dorsal vertebrae. The head, in which is situated

Coracoid process.

Spine.

Superior angle
Supragpinous fossa. "

Acromion.

~~* Neck of scapula .

Infraspinous fossa.

Axillary border.

Inferior angle.

FIG. 69.— Left scapula, posterior surface (after Toldt).

the glenoid cavity for articulation with the humerus
or upper arm bone, is surrounded by a slight con-
striction, the neck. Above it projects the coracoid
process, so calledjrom its fancied resemblance to a crow's
beak. This can usually be felt about one inch from
the juncture of the outer and middle thirds of the clav-
icle and from it arise the short head of the biceps and
the coraco-brachialis muscle. The acromion process
at the end of the spine extends out beyond the glenoid
cavity posteriorly and affords attachment to the del-

174 THE UPPER EXTREMITIES.

toid and trapezius muscles. It forms the sunlmit of
the shoulder. Numerous other muscles are attached
to the surface of the scapula, the only parts
which are truly subcutaneous being the whole length
of the spine and the acromion process, though the
lower angle and the cqracoid process can generally be
felt. The muscles bulge so much that the spine in
the living appears as a slight depression extending back
almost to the vertebrae. The large number of the
muscles on the shoulder and arm is due to the great
flexibility and strength required for the various uses to
which the arms are put.

Shoulder Muscles. — The most important shoulder mus-
cle is the deltoid, a large triangular muscle, which sur-
rounds and protects the shoulder-joint and gives the
shoulder its rounded form. It rises from the outer third
of the clavicle, from the acromion process, and from the
whole length of the spine of the scapula, and is inserted
by a tendon into a rough prominence on the middle of the
outer side of the humerus. It serves to raise the arm
and to draw it somewhat forward or back, according as
the anterior or posterior fibers are used. The pectoralis
major rises from the inner half of the clavicle, the front
of the sternum, and the cartilages of the true ribs and its
fibers converge to form a fan-shaped muscle, which is in-
serted by a flat tendon into the edge of the bicipital
groove on the humerus. It draws the arm forward and in-
ward and helps considerably in forced inspiration. The
serratus magnus rises from the outer surface and upper
border of the eight upper ribs and from an aponeuro-
sis covering the upper intercostal spaces, and is inserted
along the whole length of the posterior border of
the scapula. It carries the scapula forward and is used
in pushing.

The scapula is seldom broken because it is quite mov-
able and is covered with large muscles and because
it lies on the chest, which serves as an elastic cushion.
The acromion process is the part most frequently

THE UPPER EXTREMITIES. 175

broken and occasionally the neck is fractured. Tumors
occur and may necessitate the amputation of the whole
upper extremity.

The Humerus. — The bone of the upper arm, the hu-
merus, is the largest bone in the upper extremity and
articulates with the scapula above and with the ulna
and radius below. At its upper end are the head and
the anatomical neck, with the greater tuber osity external
to and the lesser tuberosity in front of them. The con-
striction of the surgical neck is below the tuberosities,
and extending from between them downward and in-
ward along the upper third of the bone is the bicipital
groove for the long head of the biceps. Though round
above, below the shaft becomes flattened from before
backward and curves slightly forward, terminating in
the internal and external condyles, from the former of
which the flexors and the round pronator arise and
from the latter the extensors and supinators. From
the external condyle also there projects in front the ra-
dial head or capitellum for articulation with the radius.
Internally to the capitellum in front and in a corre-
sponding position on the back of the bone are the troch-
lear surfaces for articulation with the ulna, there be-
ing a depression in front called the coronoid fossa for the
reception of the coronoid process of the ulna in flexion
of the forearm, and another depression behind, the
olecranon fossa, to receive the tip of the olecranon
process during extension. On the lower half of the
humerus at the back is the spiral groove for the musculo-
spiral nerve and the superior profunda artery, while the
ulnar nerve runs in a groove back of the internal condyle.

The humerus is almost completely covered with mus-
cles, the only part that is subcutaneous being a small
portion of the external and internal condyles. The
head can be felt under the muscles and the greater
tuberosity forms the point of the shoulder. When the
arm is at the side, the biceps appears at the front and
inner side and the brachialis anticus on either side be-

176

THE UPPER EXTREMITIES.

low, while on the back of the arm, with its largest swell-
ing above, is the triceps.

Upper Arm Muscles. — The biceps is the most important
arm muscle. It rises by a short head from the coracoid
process of the scapula and by a long head from a tubercle

FIG. 71.

FIG. 70. — Superficial muscles of shoulder and arm (from before): 1, Pectoralia
major; 2, deltoid; 3, biceps brachii; 4, brachialis anticus; 5, triceps; 6, pronator
radii teres; 7, flexor carpi radialis; 8, palmaris longus; 9, flexor carpi ulnaris;10,
supinator longus; 11, extensor ossis metacarpi pollicis; 12, extensor brevis
pollicis; 13, flexor sublimis digitorum; 14, flexor longus pollicis; 15, flexor pro-
fundus digitorum; 16, palmaris brevis; 17, abductor pollicis. (Borland's Dic-
tionary.)

FIG. 71. — Superficial muscles of shoulder and arm (from behind) : 1, Trapezius;
2, deltoid; 3, rhomboideus major; 4, infraspinatus; 5, teres minor; 6, teres major;
7, latissimus dorsi; 8, triceps; 9, anconeus; 10, brachialis anticus; 11, supinator
longus; 12, extensor carpi radialis longior; 13, extensor carpi radialis brevior; 14,
extensor communis digitorum; 15, extensor carpi ulnaris; 16, flexor carpi ulnaris;
17, extensor ossis metacarpi pollicis; 18, extensor brevis pollicis; 19, tendon of
extensor longus pollicis. (Borland's Bictionary.)

on the upper margin of the glenoicl cavity, the tendon
arching over the head of the humerus and descending
in the bicipital groove. It is inserted into the back of
the tuberosity of the radius and by a broad aponeurosis
into the fascia of the forearm. It flexes and supinates
the forearm and renders the fascia tense. Its inner

THE UPPER EXTREMITIES. 177

border forms a guide in tying the brachial artery, as this
artery runs along its inner side.

The brachialis anticus rises from the lower half of the
outer and inner surfaces of the humerus and is inserted
into the coronoid process of the ulna, thus covering and
proiecting the elbow-joint anteriorly. It is a flexor of
the forearm.

Another smaller muscle on the anterior arm, which
also aids in flexion, is the coraco-brachialis , which ex-
tends from the coracoid process of the scapula to the
middle of the inner surface of the humerus.

Extending the entire length of the posterior surface
of the humerus is the triceps, similar to the quadriceps
extensor in the thigh and direct antagonist to the bi-
ceps and brachialis anticus muscles. It rises by a long
head from below the glenoid fossa, by the external head
from the upper third of the posterior surface of the
humerus, and by the internal head from the middle
and lower thirds of the posterior surface. It is inserted
in the olecranon process of the ulna and serves to extend
the forearm and arm.

The humerus is more often fractured by muscular
action than any other bone. Usually the fracture oc-
curs in the lower half of the bone and sometimes the
musculo-spiral nerve is involved. There is a great ten-
dency to non-union, probably due to interposition of
soft parts. Sometimes the break is across and down
between the condyles, T-fracture. Involvement of the
elbow-joint is more serious than fracture of the humerus
alone. Sarcoma of the humerus does occur and may
require the removal of the clavicle and scapula as well
as of the arm bone itself. In amputation of the hum-
erus in children a long skin flap is left to allow for growth
of the bone, as it is liable to grow again.

The Ulna.— In the forearm there are two bones, the ulna

and the radius, of which the former is the longer. The

ulna is on the inner side of the forearm and its upper end

forms the greater part of the articulation with the humerus,

178 THE UPPER EXTREMITIES.

as most of the articulation at the wrist is formed by the
radius and the inter-articular fibro-cartilage. The head
of the ulna is at the lower extremity of the bone and
articulates on the outer side with the radius and below
with the triangular fibro-cartilage. From its inner side
projects the styloid process. The olecranon process
forms the upper extremity and presents anteriorly an
articular surface, the greater sigmoid cavity, for articula-
tion with the trochlea of the humerus, where it fits into
the olecranon fossa during extension. The same articu-
lating surface also covers the coronoid process, a smaller
projection below and in front of the olecranon, which
fits into the coronoid fossa during flexion. Continuous
with the greater sigmoid cavity on the outer side is the
lesser sigmoid cavity for articulation with the head of the
radius. Under the triceps tendon, which is inserted into
the olecranon, is a bursa or sac of synovial membrane,
such as occurs in parts where much force is brought to
bear.

The Radius. — The radius, or spoke of the wheel, is
on the outer side of the forearm and gets its name from
the way it turns upon the ulna in pronation. The
shaft is larger below than above and is slightly curved
longitudinally for greater strength. The upper extrem-
ity or head is small and has a slightly concave upper
surface for articulation with the radial head of the hu-
merus. It articulates by its sides with the lesser sig-
moid cavity and is bound to the ulna by the orbicular
ligament, which runs over a smooth articular surface.
Below the head is the constriction of the neck with the
tuberosity for the biceps tendon to the inner side below.
The lower extremity is large and forms the chief part of
the wrist-joint, articulating with the semilunar and
scaphoid bones of the wrist. From the lower extremity
the strong conical styloid process projects externally.

In the living the olecranon process of the ulna is always
felt at the elbow and the posterior border of the ulna
forms the prominent ridge down the forearm, leading

THE UPPER EXTREMITIES.

179

to the styloid process. The head of the radius is felt
just below the external condyle and often makes a dim-
ple in the muscles of the forearm. The rest of its

Tuberosity.

Arterial foramina. -.=:--- -

Radius. ...

Interosseous space. „

.- .Ulna.

FIG. 72. — Bones of the right forearm in a position of supination. (Toldt.)

upper half is concealed with muscles, but the lower half
is easily felt as there are only tendons over it. The
styloid process is felt externally. Normally that of the
radius is a little lower than that of the ulna, so that

180 THE UPPER EXTREMITIES.

in cases of fracture their relative position is of consid-
erable importance as showing the amount of deformity.

The two forearm bones are more frequently broken
together than separately and generally by direct vio-
lence, the lower fragment being usually drawn up by
the action of the flexor and extensor muscles and pro-
ducing a swelling on the palmar surface of the forearm.
Indirect violence usually causes fracture of the radius
only. In both cases, but especially in fracture of both
bones, there is a tendency for membrane to get between
the fragments, so the arm is put up in splints with the
hand midway between pronation and supination in
order to separate the bones as far as possible. Care
must be taken not to have the bandage too tight or gan-
grene of the fingers may result. In most fractures of
the arm it is put up bent, but in fracture of the olecranon
it is put up fully extended, as the fragment is sure
otherwise to be displaced by the pull of the triceps. In
fact, the olecranon is sometimes fractured by the mus-
cular force of the triceps, though usually its fracture,
which is frequent, is due to direct violence. The ulna
is also often fractured in the middle by direct violence
or the styloid process may be broken. Fracture of the
neck or shaft of the radius is very common, the most
important arm fracture being that of the lower end
of the radius or Colles' fracture. This and the corre-
sponding fracture in the leg, Pott's fracture, are two of
the commonest fractures. In dislocation of the wrist
the normal relation of the two styloid processes remains
unchanged, but in Colles' fracture the lower fragment
often projects on the back of the hand, making a typical
deformity called the silver fork deformity.

The bones of the wrist and hand had best be de-
scribed before the forearm muscles are taken up, as the
muscles of the forearm are distributed largely to the
fingers.

The Wrist. — The wrist or carpus is made up of eight
bones arranged in two rows of four each. In the first

THE tJPPER EXTREMITIES. 181

row are the scaphoid and semilunar bones, on the outer
side, articulating with the radius, the cuneiform artic-
ulating with the fibro-cartilage of the wrist-joint, and
the pisiform. In the second row, in corresponding posi-
tions, are the trapezium, trapezoid, os magnum, and
unciform. The eminence felt on the radial side of the
wrist is the protuberance of the scaphoid, while the
pisiform is generally felt on the ulnar side.

FIG. 73.— Right carpal bones, dorsal surface. T, trapezium; T', trapezoid;
7, os magnum; U, unciform; S, scaphoid; L, semilunar; C, cuneiform, P, pisiform.

The Hand. — The hand contains nineteen bones, five
metacarpal bones, one for each finger and the thumb,
whose bases articulate with the lower row of wrist bones,
and fourteen phalanges, three for each finger and two
for the thumb, of which the first row articulate with the
metacarpal bones. They are all long bones and are
slightly concave anteriorly. When the hand is flexed it
is the heads of the metacarpal bones, not the bases of
the phalanges, that are so prominent, the head of the
third metacarpal being most prominent.

The metacarpals are seldom fractured, though bad
fractures occasionally occur. In comminuted fracture
nothing can be done but remove the bone. If the peri-
osteum is left the bone will grow again. Two diseases

182 THE UPPEK EXTREMITIES.

sometimes affect the metacarpals and the phalanges,
tuberculosis and syphilis. Both cause swelling of the
bones.

Muscles of the Forearm. — The chief groups of muscles
on the forearm are the flexors and pronators on the an-
terior surface and the extensors and supinators on the
posterior surface. In general the flexors and pronators
take their origin from on or around the internal con-
dyle, while the extensors and supinators arise on or
around the external condyle. Where not otherwise
stated it will be understood that such is their origin.
In a general way they may by grouped as follows:

ANTERIOR SURFACE.

[ flexor carpi radialis

Flexors of wrist j flexor carpi ulnaris

( palmaris longus

f flexor sublimis digitorum
Flexors of fingers . ,

[ flexor profimdus digitorum

Flexor of thumb flexor longus pollicis

f pronator radii teres
Pronators of hand

[ pronator quadratus

POSTERIOR SURFACE.
Extensor of forearm anconeus

{extensor carpi radialis longior
extensor carpi radialis brevior
extensor carpi ulnaris
extensor ossis metacarpi pollicis

Extensors of thumb

extensor primi internodii pollicis

extensor secundi internodii pollicis
Extensor of fingers extensor communis digitorum

Extensor of index finger extensor indicis
Extensor of little finger extensor minimi digiti

f supinator longus

Supinators of hand .

[ supmator brevis

THE UPPER EXTREMITIES. 183

Of the flexors of the wrist the flexor carpi radialis is
inserted into the base of the index and usually of the
third metacarpal bone, the flexor carpi ulnaris into the
fifth metacarpal, the pisiform and the unciform bones,
while the palmaris longus goes to the anterior annular
ligament of the wrist and the palmar fascia of the hand.
The flexor sublimis digitorum is inserted by four tendons
into the second phalanges of the fingers, while the flexor
profundus digitorum arises from the upper part of the
ulna and is inserted into the last phalanges of the fingers.
The flexor of the thumb arises from the middle of the
radius and is inserted into the last phalanx of the thumb.
Which joint is flexed by a muscle depends upon the
origin and insertion of the muscle, all those included be-
tween being affected. Thus, the flexor sublimis digi-
torum, which has its origin in part at least from the
condyle and is inserted in the second phalanges of the
fingers, flexes the forearm, wrist, and all the finger-joints
but the last, while the flexor profundus digitorum, arising
from the ulna, though it flexes the wrist and fingers, has
no power of flexing the forearm.

The pronator radii teres, besides arising from the supra-
condylar ridge, rises from the coronoid process of the
ulna. It is inserted into the middle of the outer sur-
face of the radius and serves to pronate the forearm.
The other pronator, the pronator quadratus, is a small
quadrilateral muscle extending transversely across
the radius and ulna just above their carpal extremities.
It rises from the anterior surface of the ulna and is
inserted into the anterior external border of the radius.

On the back of the forearm the anconeus serves to
extend the forearm only, being inserted into the upper
part of the posterior surface of the ulna. The exten-
sors of the wrist are inserted into the bases of the various
metacarpal bones and have some power to extend the
forearm as well as the wrist. The extensors of the thumb,
as their names imply, go one to the metacarpal bone
and one to each of the phalanges, the longest one ex-

184 THE UPPER EXTREMITIES.

tending the whole thumb, the others only a part. They
rise from the ulna and radius, not the condyle. The
extensor communis digitorum goes to all the phalanges
of all the fingers, the extensor minimi digiti to those of
the little finger only, and the extensor indicis to those
of the index finger, the last two arising short of the
condyle.

Of the supinators the longer one is inserted into the
styloid process of the radius, while the shorter one, the
supinator brevis, is inserted into the upper part of the
same bone, both thus serving to turn the radius on the
ulna.

Where the tendons of the various muscles pass over
the wrist, both front and back, they are covered with a
synovial sheath and are held down by a broad ligament,
which some of them perforate, the annular ligament.
The strong fibrous band of the anterior annular ligament
arches over the carpal bones in front. Beneath it pass
the median nerve and the tendons of the flexors of the
fingers and thumb. The posterior annular ligament is of
less importance.

The deep palmar fascia forms a sheath for the muscles
of the hand. In carpenters there sometimes occurs
Dupuytren's contraction of the palmar fascia, which
draws the fingers up. As operation is not always suc-
cessful, it is quite a serious matter.

The muscles of the hand itself include various abduc-
tor, adductor, and short flexor muscles of the thumb
and little finger. There also extend between the meta-
carpal bones the lumbricales, four small muscles that
aid the deep flexor muscles; likewise seven interossei,
of which four are dorsal and three palmar. The dorsal
interossei arise by two heads from the adjacent sides
of the metacarpal bones and are inserted into the bases
of the first phalanges, thus abducting the fingers; while
the palmar interossei, arising from the palmar surface
of the second, fourth, and fifth metacarpals, are inserted
into the three corresponding first phalanges and adduct

THE UPPER EXTREMITIES. 185

the fingers toward an imaginary line drawn through
the middle finger.

Joints of the Upper Extremity. — The joints of the upper
extremity, with the exception of the wrist-joint, are the
most freely movable of any in the body, probably be-
cause the hand has the finest work to do and a greater
number of motions are required. Even the wrist has
much greater freedom of motion than the corresponding
joint in the lower extremity.

The shoulder- joint is rather a deep joint, to allow of
the varied motion required, and has a capsular ligament
from the margin of the glenoid fossa above to the neck
of the humerus below. The elbow, which is a hinge
joint, has an anterior and a posterior ligament and
two lateral ligaments, as is practically the case in all such
joints. The wrist has several ligaments which, taken
together, are capsular in nature.

Blood Supply of the Upper Extremity.— The blood
supply of the upper extremity comes through the sub-
clavian artery, which, on the right, springs from the
innominate artery and on the left from the aortic arch. It
remains one trunk as far as the elbow, though different
names have been given to different parts. Thus, as
it passes over the lower border of the first rib, it becomes
the axillary, and at the lower border of the axilla,
where it starts down the arm, the brachial. At the el-
bow it divides into the ulnar and radial arteries.

In its upper part the brachial artery lies internal to
the humerus but below it is in front of the bone. The
radial runs in a line from the middle of the elbow an-
teriorly to the inner side of the styloid process of the
radius and is much exposed to injury in the lower third
of its course, as when the hand is thrust through glass.
On it at the wrist the pulse is counted. It is much
smaller than the ulnar and winds around the outer side
of the thumb to the palm, where, with the deep branch
from the ulnar, it forms the deep palmar arch. The
ulnar artery passes obliquely inward to the middle of the

186 THE UPPER EXTREMITIES.

forearm and thence aiong its ulnar border to the palm
of the hand, where it divides into the deep branch and
the superficial palmar arch which supplies the four
digital arteries.

From the axillary artery branches go to the chest
wall and shoulder, the most important being the two
circumflex arteries to the deltoid. The brachial has only
two branches of any importance, the superior and in-
ferior profunda, both on the upper arm, of course.

In case of hemorrhage compression can frequently
be applied with the fingers where the subclavian crosses
the rib or in the axilla, where the artery can be pressed
up against the humerus.

Nerves. — The nerve supply of the shoulder comes
chiefly from the anterior and posterior thoracic, the
suprascapular , and the circumflex, these last going to
the deltoid. The biceps is supplied by the musculo-
cutaneous, the triceps by the musculo-spiral , and the
brachialis anticus by both. Most of the flexor and
pronator muscles are supplied by the median, while the
posterior interosseous and the musculo-spiral nerves go
to the extensors and supinators. The ulnar nerve sup-
plies the hand largely.

CHAPTER XIII.
THE LOWER EXTREMITIES.

The lower extremities resemble the upper very closely
in the arrangement of the bones, muscles, arteries, and
nerves, though modifications occur, due to the difference
in function of the lower limbs. There is one long bone
in the upper part or thigh, the femur, and two in the
lower part or leg, the tibia and fibula, while over the
knee-joint is the patella or knee cap. The ankle has
seven bones and the foot nineteen like the hand.

The Femur. — The femur is the longest bone in the
body, being about one-fourth the height of the person.
It inclines toward its fellow at the knee in order to
bring the knee-joints near the center of gravity in walk-
ing, the amount of inclination varying with the width
of the hips and the height of the person. On account
of the greater width of hip the tendency to knock-
knee is greater in women than in men.

The shaft of the femur is enlarged at the extremities
and is slightly curved forward, the concavity being
strengthened at the back by a longitudinal ridge, the
linea aspera, along part of which the gluteus maximus
muscle is attached. The head, which is covered with
cartilage, except for an oval depression for the attach-
ment of the ligamentum teres, one of the ligaments of
the hip joint, and which articulates with the hollow of
the acetabulum in the os innominatum, projects consid-
erably upward, inward, and forward from the shaft,
the neck varying much in length and angle. It is gen-
erally more horizontal in women than in men and in
rickets the great weight on the softened bone tends to
press the head down, causing the deformity known as

187

188

THE LOWER EXTREMITIES.

Innominnte bone. —

Femur.

Tibia.

Fibula.

Interosseous space —

Patella.

Metatarsus.

Tarsus.

M fin tarsus.

-T.""» Phalanges.
Fro. 74.— Bones of the lower extremity. (Toldt.;

THE LOWER EXTREMITIES. 189

" coxa vera" , in which the neck is almost horizontal.
Extending upward, outward, and backward from the
shaft at the base of the neck, about three quarters of an
inch lower than the head and about on a level with
the acetabulum and the spine of the os pubis, is the
greater trochanter. This large;, irregular prominence and
the smaller one of the lesser trochanter, which is at the
lower part of the base of the neck posteriorly, are for
the attachment of muscles and to assist in rotating the
bone. The lower extremity of the femur is larger than
the upper and is flat from before backward. Between
its two large eminences, the external and internal con-
dyles, is a smooth depression in front, the trochlear
surface, for articulation with the patella. The external
condyle is more prominent in front, the internal infe-
riorly, the latter being the longer of the two by about half
an inch. The epiphysis at the lower end of the femur
is the only one in which ossification has begun at birth.
Therefore, if ossification is found there, the child is known
to have arrived at full term.

So many large muscles are attached to the femur
that the shaft cannot be detected in the living unless
the person is very thin and poorly developed. The
outer surface of the greater trochanter, however, and
the condyles can be felt.

A string stretched from the anterior superior spine
of the ilium to the tuberosity of the ischium passes in
the middle just over the upper edge of the greater tro-
chanter. The line thus drawn is known as Ntlaton's
line and is of considerable importance in many condi-
tions of the hip. Thus, if the hip is dislocated, the tro-
chanter will be thrown above Nelaton's line, and in os-
tcomalacia the pelvis sinks and the trochanter is again
a hove the line.

Thigh Muscles. — Of the thigh muscles only a few need
be mentioned. One large muscle is the psoas magnus,
which has its origin on the front of the last dorsal and
all the lumbar vertebrae, passes down across the brim of

190 THE LOWER EXTREMITIES.

the pelvis and under Poupart's ligament, gradually di-
minishing in size, and terminates in a tendon that is
inserted into the lesser trochanter. It serves to flex the
thigh on the pelvis and to rotate it outward. The
psoas parvus rises from the last dorsal and the first
lumbar vertebrae and does not go out of the pelvis.

The sartorius or tailor muscle is flat and ribbon-like
and is the longest muscle in the body. It rises from
the anterior superior spine of the ilium and is inserted
into the upper inner surface of the shaft of the tibia.
B}' it the legs are crossed. It also forms the outer
side of an important landmark, Scarpa's triangle, whose
base is formed by Poupart's ligament and the inner side
by the adductor magnus muscle, which passes from the
ramus of the os pubis and the tuberosity of the ischium
to the linea aspera. The femoral artery bisects the tri-
angle and runs into its apex.

The bulk of the anterior portion of the thigh is formed
by the quadriceps extensor, which is really made up
of four muscles, the rectus femoris, whose origin is on
the anterior inferior iliac spine and above the acetab-
ulum; the vastus externus, which comes from the greater
trochanter and the upper linea aspera; and the vastus
internus and crureus, which rise from the neck of the
femur and the linea aspera. It is inserted into the tu-
bercle of the tibia by the ligamentum patella, in which
the patella lies. Its action is to extend the leg.

At the back and forming the buttocks are the three
glutei muscles, the glutens maximus, medius, and mini-
mus. All these rise from the outer side of the ilium
and have their insertion on or about the great troc-
hanter. They serve to hold the trunk erect and to
extend, abduct, and rotate the thigh.

Lower down and forming the back of the thigh are
the biceps and the semitendinosus and semimembrano-
sus muscles. The biceps rises by two heads from the
tuberosity of the ischium and the linea aspera and is
inserted into the head of the fibula. It is on the outer

THE LOWER EXTREMITIES.

191

side of the thigh and its tendon, which embraces the
external lateral ligament of the knee-joint, forms the
outer hamstring. On the inner side are the semitendi-
nosus and the semim.embranosus muscles. These rise

FIG. 75.

FIG. 76.

FIG. 77.

FIG. 75. — Superficial muscles of hip and thigh (from behind): 1, Gluteus me-
dius; 2, gluteus maximus; 3, vastus externus; 4, biceps flexor cruris; 5, semiten-
dinosus; 6, semimembranpsus ;7, gracilis; 8, sartorius; 9, adductor magnus; 10,
11, gastrocnemius; 12, origin of plantaris. (Borland's Dictionary.)

FIG. 76. — Muscles of the inner side of thigh and interior of pelvis: 1,
Iliacus; 2, psoas magnus; 3, obturator internus; 4, pyriformis1; 5, erector spinse;
6, gluteus maximus; 7, sartorius; 8, adductor longus; 9, gracilis; 10, adductor
magnus; 11, semimembranosus; 12, semitendinosus; 13, rectus femoris; 14, vas-
tus internus. (Borland's Dictionary.)

FIG. 77. — Superficial muscles of front of thigh: 1, Insertion of external oblique
into iliac crest: 2, aponeurosis of external oblique; 3, external abdominal ring;
4, gluteus medius; 5, tensor vaginae formoris; 6, sartorius; 7, iliopsoas; 8, pecti-
neus; 9, adductor longus; 10, gracilis; 11, adductor magnus; 12, vastus exter-
mus; 13, rectus femoris; 14, vastus internus; 15, biceps flexor cruris. (Dorland'a
Dictionary.)

from the tuberosity of the ischium and are inserted,
the one into the upper inner surface of the shaft of the
tibia and the other into the internal tuberosity of the
tibia. Their tendons form the inner hamstring. Like
the biceps they serve to extend the thigh and flex the

192 THE LOWER EXTREMITIES.

leg on the thigh, but where the biceps rotates the leg
out they, being attached to the inner side of the leg
bones, rotate it in.

The patella, or small pan, is a flat, somewhat triangular
bone developed in the quadriceps extensor tendon. Four
muscles are attached to it as well as the ligamentum
patellae, which holds it to the tibia and gives increased
leverage by making the quadriceps extensor work at a
greater angle. It articulates with the condyles and
serves to protect the joint. One bursa, the prepatella
bursa, separates it from the skin and another, surrounded
by adipose tissue, from the head of the tibia. The ex-
ternal surface can be seen and felt on the front of the
knee and the bone can be moved from side to side when
the leg is straight.

Joints of the Lower Extremity. — The hip-joint is a
ball-and-socket joint but is not so freely movable as
the shoulder-joint, the head of the femur being held in
the acetabulum by many strong ligaments, of which the
most important is the capsular ligament.

The knee-joint is largely a hinge-joint, but in some
positions it has some rotation. It is formed by the con-
dyles of the femur, the head of the tibia, and the patella,
and has fourteen ligaments, including the ligamentum
patella? and the crucial ligaments. Its synovial sac
is the largest found in any joint. Two semilunar
cartilages, placed on the head of the tibia, serve to deepen
the socket for the condyles, changing somewhat in shape
and thickness as the joint moves. The interval between
the thigh and the leg bones can be felt at the knee.
When the leg is extended the juncture of the bones is
slightly above the patella, while in flexion a knife passed
below the apex of the patella will pass into the joint.

Congenital dislocation of the hip occurs. Separation of
the epiphysis of the femur may occur and sometimes the
neck, rarely the lower part of the shaft, is fractured.
Either condyle may be fractured off or there may be a
T-fracture, in which case the popliteal artery may be

THE LOWER EXTREMITIES.

193

injured. In dislocation the head may be behind or in
front of the acetabulum. Impacted hip, where the neck
of the femur has, in a fall, been driven into the head, is
common in old people. Sometimes, especially in young
children, the bone is infected, osteomyelitis. Sarcoma
occurs. Most tubercular disease of the hip originates at
the upper extremity of the femur, tuberculosis generally

FIG. 78.

FIG. 79.

Fro. 78. — Right knee-joint, posterior view. (Leidy.)

FIG. 79.— Right knee-joint, showing internal ligaments: 2, anterior crucial
ligament; 3, posterior crucial ligament; 4, transverse ligament; 6, 7, semilunar
fibroeartilages. (Leidy.)

starting in the head and then attacking trie capsule and
the soft parts of the joint. If neglected, shortening of
the leg may result, in which case the bone has to be
broken and set at an angle in order to enable the child to
walk.

Occasionally a bit of cartilage gets broken off in the
knee-joint and wedged between the bones, so that the
joint cannot be straightened. This is dislocation of the
semilunar cartilage and necessitates an operation for
removal of the piece. The cartilage will eventually be
replaced by fibrous tissue and in a few months the leg

194 THE LOWER EXTREMITIES.

will be all right. Dislocation of the knee is rare, though
it may occur in any direction. Often the bursae of the
joint are irritated, as by kneeling to scrub floors, and
bursitis or housemaid's knee results. Fracture of the
patella may be caused by muscular traction or by direct
violence, and is generally repaired by making an incision
and sewing the parts of the bone together. Tumor albus
or white swelling is tuberculosis of the knee and is fairly
common in children. Specific knee means syphilis of the
knee and generally occurs in both knees.

The Tibia. — The tibia or shin bone is next longest
to the femur and is on the inner side of the leg, corre-
sponding to the ulna in the arm. The shaft is prismoid
and is more slender for the lower quarter, where fracture
is consequently most frequent. The anterior border
forms the crest or shin and can be felt for its upper two-
thirds. The lower extremity, which is smaller than
the upper, articulates with the astragalus bone of the
ankle and with the fibula. Its head or upper extremity
is expanded into two lateral tuberositis for articulation
with the femur and for muscular attachment, both of
which can easily be felt just below the bend of the knee.
Their upper surfaces are smooth and concave, with a
vertical bifid spine in the middle and a prominent
tubercle for the attachment of the scmilunar cartilages
on either side. On the anterior surface of the head,
below, is a rough eminence or tubercle, which also can be
felt. The lower part of this is for the attachment of the
ligamentum patellae, while the upper part, which is
smoother, is for the bursa that is placed under the tendon
to prevent friction. On the back of the outer tuberosity
is a facet for the head of the fibula. At the lower end
there projects downward on the inner side, overhanging
the arch of the foot, the internal malleolus, the prominent
part of the ankle. It is on a higher level and somewhat
farther forward than the external malleolus.

The Fibula. — The fibula is the most slender of all the
bones in proportion to its length and is on the outer side

THE LOWER EXTREMITIES. 195

of the leg. Its head is small and placed toward the
back of the tibia below the knee-joint, from which it is
excluded. The head articulates with the external
tuberosity and has extending upward from it the styloid
process. To it is attached the biceps tendon or outer
hamstring. At the lower extremity of the shaft is the
external malleolus, which articulates with the astragalus
and forms the outer ankle. The only parts of the fibula
that can be felt, besides the malleolus, which is very
prominent, are the head and the lower external surface
of the shaft.

In fracture of the leg both bones are usually broken,
though either may be broken separately. Pott's fracture
is fracture of the lower fibula, and may be caused by
stamping hard when stepping on to the sidewalk. In
rickets the tibia becomes bowed outward and forward,
causing bow leg, a condition which in very young children
may be rectified by manipulation. Later on braces are
needed and after five years the bones have to be broken
and set straight.

The Ankle. — The ankle or tarsus has but seven bones
where the wrist has eight. They are the os calcis or
heel bone, which is the largest and strongest and forms
the tuberosity of the heel; the astragalus, which is next
largest and helps to form the ankle-joint; the cuboid; the
navicular (boat-like) or scaphoid; and the internal, mid-
dle, and external cuneiform bones. The astragalus is
above and partially in front of the os calcis, to which is
attached the tendo Achillis. The cuboid is on the outer
side of the foot, in front of the os calcis and behind the
metatarsals. It is noticeable in congenital club-foot, in
which condition the tarsal bones may be distorted in
shape and misplaced. The navicular or scaphoid is on
the inner side of the foot, between the astragalus and
the three cuneiform bones.

The Foot. — There are five metatarsal bones in the foot,
corresponding to the five metacarpals in the hand, and
the toes have the same number of phalanges as the

196 THE LOWER EXTREMITIES.

fingers, though they are shorter and stronger. The big
toe corresponds to the thumb.

Fracture of the os calcis and the astragalus are most
commonly caused by a fall from a height, while the
metatarsals and phalanges are generally broken by some-
thing heavy falling upon them. Because of their delicate
structure, their distance from the heart, and the differ-

FIG. 80. — Bones of the right foot, dorsal surface: 1, Astragalus; 3, os calcis,
4, navicular; 5, internal cuneiform; 6, middle cuneiform; 7, external cuneiform;
8, cuboid; 9, metatarsus; 10-14, phalanges. (Leidy.)

ences of temperature to which they are subjected, the
tarsal bones are especially liable to become tubercular,
amputation of the feet even becoming necessary at times.
In diabetes there may be a perforating ulcer on the sole
of the foot and the bone may become diseased.

Muscles of the Leg. — The greater part of the calf of the
leg is formed by the gastrocnemius , a large bulging mus-
cle, which rises from the condyles of the femur and is
inserted along with the soleus, whose origin is on the

THE LOWER EXTREMITIES.

197

back of the upper fibula, and the plantaris, which comes
from the linea aspera, into the os calcis by a common ten-
don, the tendo Achillis, the largest and strongest tendon
in the body. Its action is to extend the foot and to

FIG. 81.

FIG. 82.

FIG. 83 .

FIG. 81. — Superficial muscles of the leg from inner side: 1, Vastus internus; 2,
sartorius; 3, gracilis; 4, semitendinosus ; 5, semimembranosus; 6, inner head of
gastrocnemius; 7, soleus; 8, tendon of plantaris; 9, tendon of tibialis posticus; 10,
flexor longus digitorum; 11, flexor longus hallucis; 12, tibialis anticus; 13, ab-
ductor hallucis. (Borland's Dictionary.)

FIG. 82. — Muscles of leg and foot (from before): 1, Tendon of rectus femoris;
2, vastus internus; 3, vastus externus; 4, sartorius; 5, iliotibial band; 6, inner
head of gastrocnemius; 7, inner part of soleus; 8, tibailis anticus; 9, extensor
proprius hallucis; 10, extensor longus digitorum; 11, peroneus longus; 12, pero-
neus brevis; 13, peroneus tertius; 14, origin of extensor brevis digitorum.
(Borland's Dictionary.)

FIG. 83. — Superficial muscles of leg (from behind) : 1, Vastus externus; 2, biceps
flexor cruris; 3, semiteTidinosus; 4, semimembranosus; 5, gracilis; 6, sartorius; 7,
outer, and 8, inner, head of gastrocnemius; 9, plantaris; 10, soleus; 11, peroneus
longus; 12, peroneus brevis; 13, flexor longus digitorum; 14, tibialis posticus; 15,
lower fibers of flexor longus hallucis. (Dorland's Dictionary.)

rotate it slightly inward. Other extensors of the foot,
which also evert it, are the peroneus longus and the
peroneus brevis at the upper and outer part of the leg, the
former rising from the outer tuberosity of the tibia and

198 THE LOWER EXTREMITIES.

the upper fibula and being inserted into the first metatar-
sal and the internal cuneiform, the latter arising from the
lower fibula and being inserted into the fifth metatarsal.
The foot is flexed, adducted, and rotated inward by
means of the tibialis anticus, which rises from the outer
tuberosity and the upper two-thirds of the outer surface
of the tibia and is inserted into the internal cuneiform
bone.

In the foot, and corresponding to the palmar fascia in
the hand, is the plantar fascia, the densest of all fibrous
membranes. There are also various annular ligaments,
and the foot muscles are arranged similarly to those in the
hand.

The Blood Supply of the Lower Extremity.— The
blood supply of the lower extremity comes from the
external iliac artery , a branch of the common iliac,
which passes obliquely downward and outward along
the border of the psoas muscle to Poupart's ligament,
where it enters the thigh and becomes the femoral artery.
Its only important branches are the deep epigastric,
which goes up along the internal abdominal ring, and the
deep circumflex iliac. As the femoral artery it passes
down the inner side of the thigh to the internal condyle
of the femur, being very superficial at Scarpa's triangle,
where it can be compressed with the thumb to stop
hemorrhage below. If a tourniquet is applied, it should
be applied a little lower down. The first and most
important branch of the femoral is the profunda femoris.

About two-thirds of the way to the knee the artery
takes the name popliteal. It lies superficially in the
popliteal space back of the knee, but above and below it
is covered with muscles. Its branches supply the knee-
joint and nearby muscles and are unimportant. At the
lower border of the popliteus muscle, a small muscle at the
knee, it divides into the anterior and posterior tibial
arteries. The course of the former of these may be marked
by a line from the inner side of the head of the fibula to
midway between the malleoli at the front of the ankle,

THE LOWER EXTREMITIES. 199

where it terminates in the dorsalis pedis artery for the
back of the foot. By this last the pulse is sometimes
taken and its pulsation is a guide in determining how
high up to amputate in gangrene of the foot. The
posterior tibial extends obliquely down the back of the
leg to the heel, where it divides into the internal and
external plantar arteries which go to the sole of the foot.
Its most important branch is the peroneal.

Besides the deep veins accompanying the arteries
there are the superficial veins, the internal or long saphen-
ous on the inner side of the leg and thigh and the external
or short spahenous on the middle of the leg posteriorly
and emptying into the popliteal vein. Varicosity often
occurs in these veins.

Nerves. — The nerves of the muscles about the hip are
branches of the lumbar nerve. The anterior crural sup-
plies the anterior part of the thigh, the gluteal the
muscles of the same name, and the great sciatic the large
muscles of the back of the thigh. Below the knee the
anterior tibial goes to the tibialis anticus and the in-
ternal popliteal to the muscles of the calf, while the
peroneus muscles are supplied by the musculo-cutaneous.

NDEX.

ABDOMEN, 132

muscles, 132, et seq.

nerves, 134

regions, 134, 135

contents, 135, 136
Abdominal aorta, 107, 109
Abducens nerve, 83
Abscess, 34, 51, 52, 100, 137,

152, 159, 168

Absorbent vessels or lymph-
atics, 34

Absorption of food, 33
in intestines, 144
in mouth, 136
in stomach, 140
Accommodation of eye, 72
Acetabulum, 162, 187
Acromion process, 173
Adam's apple, 121
Adductor magnus muscle, 190
Adenoids, 62
Adipose tissue, 16
Air, changes by breathing, 129,
130

complemental, 129

residual, 129

supplemental, 129

tidal, 129
Air cells, 27
Albumin in urine, 158
Albuminoids, 12
Alimentary canal, 136, et seq.
Alveoli of lungs, 126

Amoeba, 12

Ampulla3 of mamma or breast,

100

Amputation, 177
Amylopsin, 144
Anabolism, 147
Anasarca, 152
Anatomy, 11

Anconeus muscle, 182, 183
Anemia, 120
Aneurism, 109
Ankle, 195

Annular ligaments, 184, 198
Ano-spinal reflex, 146
Antrum of Highmore, 54, 57
Anus, 141, 146
Aorta, 99, 107, 109
Aortic valve, 104
Aponeuroses, 23
Apoplexy, 79, 118
Appendages of the skin, 40
Appendix, vermiform, 145
Aqueous humor, 70
Arachnoid, 76
Areola, 100
Areolar tissue, 15
Arteries, 27, 28, 29, 107

nerves, 29

of back, 94, 95

of brain, 77

of breast, 100

of chest, 99

of heart, 107

201

202

INDEX.

Arteries of intestine, 143, 145
of kidney, 156
of lower extremity, 198, 199
of organs of generation, 168
of pancreas, 153
of spleen, 153
of stomach, 139
of upper extremity, 185, 186
structure, 27
Artery, axillary, 99, 100, 108,

185

basilar, 77, 108
brachial, 108, 177, 185
carotid, common, 107, 108

internal and external, 108,

137

celiac axis, 109, 143, 150, 153
cerebral, 77
circumflex, 186
coronary, 107
communicating, 78
digital, 186
dorsalis pedis, 199
epigastric, deep, 198
facial, 28
femoral, 190, 198
gastric, 109
hepatic, 109, 150
iliac, common, 107, 109

internal and external, 95,
109, 198

circumflex, 198
innominate, 107
intercostal, 95, 97, 100, 108
lumbar, 95, 109
mammary, internal, 99, 100,

108

mediastinal, 99
mesenteric, 109, 143, 145, 153
ophthalmic, 70
peroneal, 199
phrenic, 99, 109

Artery, plantar, internal and

external, 199

popliteal, 198

profunda, superior and in-
ferior, 175, 186
femoris, 198

pudic, 168

pulmonary, 106, 110

radial, 108, 185

renal, 109

spermatic or ovarian, 109, 168

splenic, 109, 153

subclavian, 94, 99, 107, 108
185

suprarenal, 109

suprascapular, 94

thyroid axis, 108

tibial, 198

transversalis colli, 94

ulnar, 108, 185

umbilical, 107

uterine, 168

vertebral, 77
Arytenoid cartilages, 122
Ascending aorta, 107

colon, 145
Ascites, 34, 152
Asphyxia, 128
Astigmatism, 73
Astragalus, 195
Atlas, 91
Auditory meatus, 52

canal, external, 63
internal, 64

center, 81

nerve, 64, 65, 84
Auricles of heart, 103
Axilla, 32
Axillary artery, 99, 100, 108,

185

Axis, 91
Axis-cylinder process, 36, 37

INDEX.

203

BACK, 88, et seq.

muscles, 93, 94

arteries, 94, 95

nerves, 95

Basilar artery, 77, 108
Basilic vein, 109
Biceps of arm, 175, 176

of leg, 190, 191
Bicipital groove, 175
Bicuspid or mitral valve, 104

teeth, 60
Bile, 36, 143, 150
Bilirubin, 12, 143, 151
Biliverdin, 143, 151
Bladder, 160
Blind spot, 70
Blood, 27, 116, et seq.

amount, 116

arterial and venous, 29

circulation of, 29, 105, et seq.

coagulation, 117, 118

coloring matter, 119

composition, 116, 117

corpuscles, 116, 118, et seq.

fibrin, 117

functions of, 116

plaques, 120

plasma, 33, 116, 117

pressure, 114, 115

serum, 117

vessels, 27, et seq.
Bone, 17

astragalus, 195

atlas, 91

axis, 91

canaliculi, 17

cancellous or spongy, 17

carpal, 180, 181

chemical composition, 18

clavicle, 171

coccyx, 90, 161

compact, 17, 18

Bone, cuboid, 195
cuneiform, 181, 195
endosteum of, 18
ethmoid, 48, 53
femur, 187
fibula, 194, 195
formation of, 18
frontal, 49

Haversian canals of, 17
humerus, 175
hyoid, 60
ilium, 161, 162
incus, 63

innominate, 161, 162
ischium, 161, 163
lachrymal, 48, 54
lacunae of, 17
lamellae of, 17
malar, 48, 54
malleus, 63
marrow of, 18
maxillary, inferior, 48, 55

superior, 48, 54
metacarpal, 181
metatarsal, 195
nasal, 48, 55
navicular, 195
occipital, 48, 50
os calcis, 195
os innominatum, 161, 162
os magnum, 181
palate, 48, 54
parietal, 48, 49
patella, 19 , 192
pelvis, 161
periosteum of, 18
phalanges, of foot, 195

of hand, 181
pisiform, 181
pubes, 161, 163
radius, 178, 179
ribs, 97, 98

204

INDEX.

Bone, sacrum, 90, 161

scaphoid, 181, 195

scapula, 173

semilunar, 181

sphenoid, 48, 52

stapes, 63

sternum, 97

structure of, 17

tarsal, 195

temporal, 48, 51

tibia, 194

trapezium, 181

trapezoid, 181

turbinated, 53

inferior, 48, 53, 54

ulna, 177, 178

unciform, 181

vertebrae, 88

vomer, 48, 55
Bones, classification of, 19

flat, 20

function of, 19, 20

long, 19

of back, 88

of chest, 97, 98

of cranium, 48, et seq.

of face, 53, et seq.

of lower extremity, 187, etseq.

of upper extremity, 171, et seq.

pelvic, 161, et seq.

sesamoid, 19

short, 20

Wormian, 19, 49
Bow leg, 195
Brachial artery, 108, 177, 185

plexus, 84, 85
Brachialis anticus, 175, 177
Brain, 75, et seq.

areas, 81, 82

arteries, 77

function, 80, et seq.

parts, 75

Broad ligaments of uterus, 165,

166, 168

Bronchi, 123, 125
Buffy coat, 117
Bursse, synovial, 20, 178
Bursitis, 194
Buttocks, 190

CANAL, alimentary, 136, et seq.

auditory, 63, 64

central, of cord, 81

Haversian, 17

semicircular, 64, 66
Canaliculi of bone, 17
Cancellous tissue of bone, 17
Cancer, 35, 58, 62, 100, 122,

139, 146, 169
Canine teeth, 60
Canthus of eye, 67, 68
Capillaries, 28, 29
Capitellum, 175
Capsular ligament of hip, 193
Carbohydrates, 12, 26, 147, 148,

151
Cardiac cycle, 104

muscle, 22, 25

nerve, 78

plexus, 87
Caries, 98
Carotids, common, 107, 108

internal and external, 108,

137

Carpal bones, 180, 181
Carpus or wrist, 180, 181
Cartilage, 16
Cartilages, arytenoid, 122

costal, 98

cricoid, 121

thyroid, 121

triangular, 57
Casein, 11
Cauda equina, 79, 91

INDEX.

205

Cecum, 145

Celiac axis, 109, 150, 153

Cells, 12, 13

Central canal of cord, 81

Cephalocele, 53

Cerebellum, 51, 78

Cerebral arteries, 77

veins, 78

Cerebro-spinal fluid, 34, 76, 79
meningitis, 79
nervous system, 75, et seq.
Cerebrum or brain proper, 51,

Cervical nerves, 84
plexus, 84
vertebrae, 90, 91
Cervix of uterus, 168
Chemical composition of the

body, 11
of bone, 18
Chest or thorax, 96
arteries, 99
bones, 97, 98
muscles, 98, 99
nerves, 99
Cholesterin, 143
Chorda tendineae, 104
Choroid, 68

Chromatic aberration, 73
Chyle, 32, 33, 144
Chyme, 139, 140
Cilia, 15, 27
Ciliary muscles, 69, 72

processes, 69, 72
Circle of Willis, 78, 108
Circulation of the blood, fetal,

106, 107
portal, 109, 110
pulmonary, 110
systemic, 105, 106, 107,

et seq., 112, 113
Circumflex artery, 186

Circumflex nerve, 85, 186
Circumvallate papilhe, 61
Cirrhosis of liver, 152
Clavicle, 171
Cleft palate, 55
Clitoris, 170

Clotting of blood, 23, 117, 118
of lymph, 33
of muscle, 23 .
Club-foot, 195
Coccygeal nerve, 84

vertebra, 90
Coccyx, 90, 161
Cochlea, 64, 65
Colics' fracture, 171, 180
Color blindness, 73

perception, 73
Coloring matters, 12

of bile, 143, 151

of blood, 119
Colon, ascending, 145
descending, 145
transverse, 145
Columnar carnese, 104
Commissures of cord, 80
Common bile duct, 150
Communicating arteries, 78
Compact tissue of bone, 17, 18
Condyles, humerus, 175

femur, 189
Conjunctiva, 67
Conjugate focus, 71
Convolutions of brain; 76
Connective tissue, 15, et seq.

areolar, 15

bony, 17

cartilaginous, 16

elastic, 15

fatty or adipose, 16

fibrous, 15

Coraco-brachialis, 177
Coracoid process of scapula, 173

206

INDEX.

Cordiform tendon, 98
Cornea, 27, 68, 70
Cornicula laryngis, 122
Coronary artery, 107

sinus, 105

valve, 105
Coronal suture, 48
Coronoid fossa, 175

process, 178
Corpus luteum, 166
Corpuscles of blood, 116, 118,
et seq.

tactile, 37, 39, 46
Corti, organ of, 65
Costal cartilages, 98
Coughing, 131
"Coxa vera," 189
Cranial nerves, 77, 78, 83, 84
Craniotabes, 53
Cranium, bones of, 48, et seq.
Cribriform plate of ethmoid

bone, 53

Cricoid cartilage, 121
Crista galli, 53
Cross eye, 72

Crossed pyramidal tract, 82
Crucial ligaments, 193
Crural nerves, 85, 199
Crureus, 190
Crying, 131
Crypts of Lieberkuhn, 143, 144,

145

Crystalline lens, 69, 70
Cuboid bone, 195
Cuneiform bones, ankle, 195

wrist, 181
cartilages, 122
Cutaneous nerves, 46, 85
Cystic duct, 143, 152

DELTOID, 174
Dendrites, 36

Derma, 39
Descending aorta, 107

colon, 145

Diabetes mellitus, 151, 196
Diaphragm, 98, 99, 128
Diaphysis, 18
Diastole, 104, 106
Differentiation of tissues, 13
Digestion, in mouth, 136

in small intestine, 143, 144

in stomach, 139, 140

of fats, 144

of proteids, 140, 144

of starch, 136, 144
Digital arteries, 186
Diphtheria, 35
Diploe, 20, 48
Direct cerebellar tract, 82

pyramidal tract, 80, 82
Dislocation, 180, 193, 194
Diuretics, 158

Dorsal or thoracic nerves, 84,
85

vertebra?, 90, 91
Dorsalis pedis artery, 199
Duct, common bile, 150

cystic, 143, 152

ejaculatory, 165

hepatic, 143, 150

lachrymal, 68

of Rivinus, 62

pancreatic, 153

right lymphatic, 31, 32

Stensen's, 62

Wharton's, 62
Ductless glands, 36
Ductus arteriosus, 106, 107

communis choledochus or

common bile duct, 150
Duodenum, 142
Dupuytren's contraction, 184
Dura mater, 15, 76, 79

INDEX.

207

EAR, 63, et seq.

external, 63
function of, 65

internal, 64
function of, 65

middle, 63

function of, 65
Edema, 33, 34, 122
Eighth nerve, 64, 84
Ejaculatory duct, 165
Elbow, 32

joint, 185
Elastic tissue, 15
Eleventh nerve, 84
Emmetropic eye, 72
Emphysema, 97
Empyema of gall-bladder, 152,
153

of lungs, 126
End bulbs, 37
Endocardium, 103
Endolymph, 64, 65
Endosteum, 18
Endothelium, 14, 40
Ensiform cartilage, 97
Epidermis, 27, 39
Epigastric artery, 198
Epigastrium, 135
Epiglottis, 60, 121, 136
Epiphysis, 18, 189, 193
Epithelium, 14, 27

ciliated, 15, 27

columnar, 14

glandular, 14

pavement, 14

simple, 14

stratified, 14
Erythrocytes, 118, 119
Esophagus, 138
Ethmoid bone, 53
Eustachian tubes, 52, 63

valve, 106, 107

Excreting glands, 35
Extensor carpi radialis longior,

182, 183

brevior, 182, 183
ulnaris, 182, 183
communis digitorum, 182,

184

indicis, 182, 184
minimi digiti, 182, 184
ossis metacarpi pollicis, 182,

183
primi internodii pollicis, 182,

183
secundi internodii pollicis,

182, 183
Eye, 66, et seq.

accommodation, 72

coats of, 68

color of, 69

formation of image in, 70,

et seq.

humors of, 70
muscles of, 67
nerves of, 67, 68
teeth, 60
Eyeball, 66
Eyebrows, 66
Eyelashes, 67
Eyelids, 66, 67

FACE, bones of, 53, et seq.
Facial artery, 28

nerve, 83, 84
Fallopian tubes, 166, 167
Far-sightedness, 72, 73
Fat or adipose tissue, 16
Fats, 12, 147, 148

absorption, 144

digestion, 143, 144
False pelvis, 163

ribs, 97
Fascia, lumbar, 133

INDEX.

Fascia, palmar, 184

plantar, 198
Fasciae, 15, 21
Fasciculi, 21
Fauces, pillars of, 59
Feces, 146
Female generative organs, 163,

165, et seq.

Femoral artery, 190, 198
Femur, 187
Fenestra ovalis, 63, 65

rotunda, 65
Ferments, 12, 136, 144
Fetal circulation, 106, 107
Fetus, 111
Fever, 45
Fibrin, 11,23,33,117

ferment, 117
Fibrinogen, 117
Fibrous tissue, 15
Fibula, 194, 195
Fifth nerve, 83
Filum terminale, 78, 91
Fimbria?, 167
First nerve, 83
Fissure of Rolando, 75, 82

of Sylvius, 75

Flexor carpi radialis, 182, 183
ulnaris, 182, 183

longus pollicis, 182, 183

profundus digitorum, 182, 183

sublimis digitorum, 182, 183
Floating ribs, 97
Follicles, Graafian, 166
Fontanelles, 19,49
Food, 147

amount, 148

classes of, 147

cooking, 148

function, 147, 148
Foot, bones of, 195, 196

muscles of, 198

Foramen, intervertebral, 90

magnum, 50

nutrient, 19

obturator, 163

of Majendie, 79

optic, 66, 70

ovale, 106
Foreign bodies, 118, 122, 137,

146
Fossa, coronoid, 175

glenoid, 51

iliac, 163

nasal, 55, 57

olecranon, 175
Fourchette, 170
Fourth nerve, 68, 83
Fovea centralis, 70
Fractures, 98, 164, 171, 174, 175,

177, 180, 181, 193, 194, 195,

196

Frenum of tongue, 60
Frontal bone, 48, 49

GALL-BLADDER 143, 152, 153

stones, 143
Ganglia, 87, 110
Gangrene, 180, 199
Gastric artery, 109

glands, 35

juice, 139

vein, 110, 150
Gastrocnemius, 196
Generative organs, female, 163,

165, et seq.
male, 163, 164, 165
Genito-crural nerve, 85
Gladiolus 97
Glands, 32, 35, 36

ductless, 36

excreting, 35

functions, 36

gastric, 35

INDEX.

209

Glands, lachrymal, 68

lymphatic, 32, 34, 35

mammary, 99, 100

Meibomian, 67

of Lieberkuhn, 143, 144, 145

parotid, 51, 62

Peycr's, 142

procreating, 165

prostate, 164, 165

racemose, 35

salivary, 35, 61, 136

sebaceous, 35, 40, 41

secreting, 35

solitary, 142, 145

sublingual, 56, 62

submaxillary, 56, 62

sweat, 35, 42

thymus, 124

thyroid, 124
Glenoid cavity, 173

fossa, 51
Globulin, 11
Glosso-pharyngeal nerve, 61,

Glottis, 122, 129
Gluteal nerves, 199
Glutei muscles, 190
Glycogen, 26, 36, 150, 151
Goiter, 124
Gonorrhea, 160, 168
Graafian follicles, 166
Gray matter of brain and cord,

36, 75, 76, 78, 80, 81
Green-stick fracture, 19
Groin, glands of, 32, 3~5
Gustatory cells, 61

HAIR, 27, 40

follicle, 40
Hamstring, inner, 191

outer, 191
Hard palate, 55, 59
14

Haversian canals, 17
Hearing, sense of, 65
Heart, 101, el seq.

beat, 102, 104, 111, 112

nerves, 110, 111

position, 102

sounds, 111

structure, 103, 104
Heat center, 45

production, 44

prostration, 45

stroke, 45

Hemoglobin, 119, 130
Hemorrhage, 139, 186
Hemorrhoidal veins, 146
Hemorrhoids, 146
Henle's loops, 156
Hepatic artery, 109, 150

duct, 143, 150

flexure, 145, 146

veins, 110
Hernia, 146, 164
Hiccough, 99, 131
Highmore, antrum of, 54, 57
Hilum of kidney, 155
Hip joint, 192
Housemaid's knee, 194
Humerus, 175
Humors of eye, 70
Humpback or Pott's disease, 91
Hydrocarbons, 12
Hydrocephalus, 34
Hydrochloric acid, 139, 140
Hydrothorax, 34
Hymen, 170
Hyoid bone, 60

Hypermetropia or far-sighted-
ness, 72, 73

Hypochondriac regions, 135
Hypogastric plexus, 87

region, 135
Hypoglossal nerve, 84

210

INDEX.

IDIOCY, 53

Ileo-cecal valve, 142, 145
Ileo-pectineal line, 163
Ileum, 142

Iliac artery, common, 107, 109
deep circumflex, 198
external and internal,

95, 109, 198
fossae, 163

Ilio-hypogastric nerve, 85
Ilio-inguinal nerve, 85
Ilium, 161, 162
Impacted hip, 193
Incisor teeth, 60
Incus, 63

Infundibula of lung, 125, 127
Inguinal regions, 135
Innominate artery, 107
bone, 161, 162
veins, 109
Inorganic compounds in body,

12
Intercostal arteries, 95, 97, 100,

108

muscles, 98, 128
nerves, 85, 97, 99, 134
Intercellular substance, 14, 17
Interossei muscles, 184
Interosseous nerves, 85, 186
Internal secretion, 36
Intervertebral foramen, 90
Intestines, 141, et seq.
large, 141, 145
function, 146
glands, 145
nerves, 145
structure, 145, 146
small, 141, 142, et seq.
blood-vessels, 143
function, 143, 144
glands, 142, 143
nerves, 143

Intestines, small, structure, 142
Intima, 27

Intralobular vein, 150
Intussusception, 146
Involuntary muscle, 21
Iris, 68, 69, 72
Ischium, 161, 103
Island of Reil, 75

JAUNDICE, 35, 152, 153, 158
Jejunum, 142
Joints, 15, 20

classes of, 20, 21

ankle, 195

elbow, 21, 185,

hip, 21, 192

knee, 193

motion of, 20, 21

shoulder, 21, 185

wrist, 185
Jugular veins, 109
Juice, gastric, 139

pancreatic, 143, 144, 153

KATABOLISM, 147
Kidneys, 155, et seq.

floating, 159

function, 156, et seq.

position, 155

structure, 155, 156,
Knee-jerk, 83
Knee joint, 193

LABI A majora, 169

minora or nympha?, 170
Labyrinth, membranous, 64, 65

osseous, 64
Lachrymal bones, 48, 54

canal, 54, 57

duct, 68

gland, 68

sac, 54, 68

INDEX.

211

Lacteals, 32, 144
Lacunae of bone, 17
Lambdoidal suture, 48
Lamellae of bone, 17
Laminae of vertebrae, 89
Large intestine, 141, 145
Laryngitis, 122
Laryngotomy, 122
Larynx, -121
Latissimus dorsi, 93
Laughing, 131
Lens, crystalline, 69, 70
Leucocytes, 33, 34, 119, 120
Levator scapulae, 93
Levatores of ribs, 129
Lieberkiihn, glands of, 143, 144,

145
Ligaments, 15, 20, 21

annular, 184, 198

broad, of uterus, 165, 166,
168

capsular, of hip, 21, 193

crucial, of knee, 193

orbicular, 178

Poupart's, 132

round, of uterus, 168

suspensory, of liver, 149

thyro-arytenoid, 122
Ligamentum nuchae, 50, 91,
93

patellae, 190, 192, 193, 194

teres, 187

Line, Nelaton's, 189
Linea alba, 132

aspera, 187
Liver, 36, 149, et seq.

blood-supply, 150

diseases of, 152

function, 150, et seq.

position, 149

structure, 149, 150
Loops of Henle, 156

Lower extremities, 187, et seq.
Lumbar artery, 95, 109

fascia, 133

nerves, 84, 85

plexus, 84

regions, 135

vertebrae, 90
Lumbricales, 184
Lungs, 125, et seq.

function, 127, et seq.

nerves, 127

position, 126

structure, 126, 127
Lupus, 58
Lymph, 30, 32

capillaries, 30

character, 32, 33

flow of, 33

function, 34

spaces, 30

transudation of, 33
Lymphatic glands, 32, 34, 35

system, 27, 29, et seq.

vessels, 30, 31

valves of, 31, 32, 33

MACULA lutea, 70

Malar or cheek bone, 48, 54

Malaria, 154

Male organs of generation, 163,

164, 165
Malleolus of fibula, 194, 195

of tibia, 194
Malleus, 63
Malpighian bodies, 156

pyramids, 156

Mammary artery, internal, 99,
100, 108

glands, 99, 100
Manubrium, 97
Marrow of bone, 18
Masseter, 51, 54

212

INDEX.

Mastoid abscess, 51, 52

cells, 51, <il

portion of temporal bone, 51
Maxillary bone, inferior, 48, 55

superior, 48, 54
Me Burney's point, 145
Meatus, auditory, 52, 65

nasal, 57

urinarius, 160, 165, 170
Median, cephalic vein, 109

nerve, 85, 186

vein, 109

Mediastinal artery, 99
Mediastinum, 32, 126
Medulla or marrow, 18
Medulla oblongata, 78, 79, 82
Medullary artery, 19

canal, 19

sheath, 37
Meibomian duct, 74

glands, 67

Membrana tympani or drum, 63
Membranous labyrinth, 64, 65
Mesenteric arteries, 109, 143,
145, 153

veins, 110, 150
Mesenteries, 32 134
Metabolism, 45, 147, 151, 152
Metacarpal bones, 181
Metatarsal bones, 195
Micturition, 157
Milk teeth, 60
Mitral valve, 104
Molar teeth, 60
Monometer, 114
Mons Veneris, 169
Motor areas, 81, 82

center, 81, 82

oculi nerve, 68, 83

tract, 82

Mouth, 59, et seq.
Mucous membrane, 40

Mucus, 40
Mumps, 62
Muscle, 21, et seq.

action, 23, 24

cardiac, 22, 25

characteristics, 22, 23, 24, 25

classes of, 21

fatigue of, 26, 27

function of, 24

smooth, 21, 25

sounds, 25

striated, 21, 23, 25

work, 25, 26
Muscles of abdomen, 132, et seq.

of arm, 175, 176, 177

of back, 93, 94

of chest, 98, 99, 128

of foot, 198

of forearm, 182

of hand, 184

of head, 50, 51, 54, 55, 58,
67, 69

of leg, 196, et ssq.

of neck, 51, 92, 93, 129

of shoulder, 174

of thigh, 189, et seq.
Musculo-cutaneous nerve, 85,

186, 199
Musculo-spiral nerve, 85, 175,

186

Musical sounds, 65
Myopia or near-sightedness, 72,

Myosin, 11, 23
Myosinogen, 23

NAILS, 27, 40
Nares, 57
Nasal bones, 55

duct, 68

fossae, 55, 57

meatus, 57

INDEX.

213

Nasal septum, 55
Navicular or scaphoid bone, 195
Near-sightedness, 72, 73
Neck, glands of, 32

muscles of, 51, 1)2
Nekton's line, 189
Nerve, 37

action of, 37, 38, 83

cell or gray matter, 36

fiber or white matter, 36

function, 37

ganglia, 87, 110

motor, 82

plexus, 29, 84, et seq.

sensory, 82, 83

terminations, 37
Nerves, 24, 36

abducens, 83

auditory, 64, 65, 84

cardiac, 78

cervical, 84

circumflex, 85, 186

coccygeal, 84

cranial, 77, 78, 83, 84

crural, anterior, 85, 199

cutaneous, 46, 85

dorsal or thoracic, 84, 85

eighth, 64, 84

eleventh, 84

facial, 83

fifth, 83

first, 83

fourth, 68, 83

genito-crural, 85

glosso-pharyngeal, 61, 84

gluteal, 199

hypoglossal, 84

ilio-hypogastric, 61, 85

ilio-inguinal, 85

intercostal, 85, 97, 99, 134

interosseous, 85, 186

lumbar, 84, 85

Nerves, median, 85, 186
motor oculi, 68, 83
musculo-cutaneous, 85, 186,

199

musculo-spiral, 85, 175, 186
ninth, 84
obturator, 85
olfactory, 53, 58, 83
optic, 70, 71, 76, 83
patheticus, 83
phrenic, 85, 99, 130
plantar, 85
pneumogastric, 84, 110, 111,

127, 130, 153
popliteal, 85, 199
post-tibial, 85
radial, 85
sacral, 84

sciatic, 85, 163, 199
second, 70, 83
seventh, 83
sixth, 68, 83
spinal, 84, 95

accessory, 84, 95, 137
suprascapular, 186
sympathetic, 87, 110, 127, 137,

143, 145, 168
tenth, 84
third, 68, -72, 83
thoracic, 186

cutaneous, 100
tibial, 86, 87, 199
trifacial, 61, 83
twelfth, 84
ulnar, 85, 175, 186
vagus, 84, 110, 111, 127,130,

153
vasoconstrictors, 115

dilators, 115

motor, 29, 78, 115
Nervous system, 38, 75, et seq.
tissue, 13, 36

214

INDEX.

Neurilemma, 37
Ninth nerve, 84
Nipple, 100
Nose, 57, 58
bleed, 59
Nucleolus, 12
Nucleus, 12
Nutrient foramen, 19
Nymphae, 170

OBLIQUE muscles of abdomen,

132

of eye, 68
Obturator foramen, 163

nerve, 85

Occipital bone, 48, 50
Occipito-frontalis muscle, 51
Odontoid process of axis, 91
Olecranon fossa, 175

process, 178
Olfactory bulbs, 53, 58, 76

cells, 58

grooves, 53

nerves, 53, 58, 83

tract, 58, 76
Omenta, 134, 146
Ophthalmic artery, 70
Optic axis, 70

commissure, 76

foramen, 66, 70

nerve, 70, 71, 76, 83

tract, 76

Orbicular ligament, 178
Orbicularis palpebrarum, 67
Orbit of eye, 54, 66
Organ of Corti, 65
Organic compounds in body, 11,

12
Os calcis, 195

innominatum, 161, 162

magnum, 181

uteri, 168

Osseous labyrinth, 64
Ossicles of ear, 63, 65
Osteoblasts, 18
Osteomalacia, 164, 189
Osteomyelitis, 193
Oval window, 63, 64, 65
Ovaries, 165
Ovum, 12, 166, 168
Oxyhemoglobin, 130

FACET'S disease, 53
Pain, sensation of, 47, 81
Palate, bones of, 48, 54

cleft, 55

hard, 55, 59

soft, 59, 60, 136
Palmar, arch, 186

fascia, 184

Palmaris longus, 182, 183
Pancreas, 153
Pancreatic duct, 143, 153

juice, 143, 144, 153
Pancreatitis, 153
Panhysterectomy, 169
Papillae of skin, 37, 39

of tongue, 61
Paralysis, 79
Parietal bone, 48, 49
Parotid gland, 51, 62
Patella or knee-cap, 19, 192
Patheticus nerve, 83
Pectoral muscles, 99, 128
Pectoralis major, 174
Pedicles of vertebrae, 89
Pelvis, 132, 161, et seq.

false, 163

of kidney, 156

true, 163, 164
Penis, 160, 165
Pepsin, 140
Peptones, 12, 140, 150
Pericardium, 34, 101, 102

INDEX.

215

Perichondrium, 16
Perineal body, 170
Perineum, 170
Perilymph, 64, 65
Periosteum, 15, 18, 19, 76
Peripheral resistance, 112, 114
Peristaltic movements, 138,143,

146

Peritoneum, 134
Permanent teeth, 60
Peroneal artery, 199
Peroneus brevis, 197

longus, 197
Petrous portion of temporal

bone, 51, 52

Peyer's patches or glands, 142
Phalanges of foot, 195

of hand, 181
Pharynx, 59, 136, 137
Physiology, 11
Phrenic artery, 99, 109

nerve, 85, 99, 130
Pia mater, 76
Pigeon breast, 97
Pillars of the fauces, 59, 60
Pink eye, 74
Pinna, 63
Pisiform bone, 181
Pituitary body, 36
Placenta, 106, 107
Plantar artery, 199

fascia, 198

nerve, 86
Plantaris, 197

Plasma of blood, 33, 116, 117
Platysma myoides, 92
Pleurae, 34, 125
Plexus, 29

brachial, 84, 85

cardiac, 87

cervical, 84

hypogastric, 87

Plexus, lumbar, 84

sacral, 84, 85

solar, 87, 153
Pneumogastric nerve, 84, 110,

127, 153
Polypi, 58
Pons Varolii, 78
Popliteal artery, 198

nerves, 86, 199

space, 32, 198
Popliteus muscle, 198
Portal circulation, 110

vein, 110, 150
Pott's disease, 91

fracture, 180, 195
Poupart's ligament, 132
Prepatella bursa, 192
Prepuce, 165
Presbyopia, 73
Presternal notch, 171
Procreating glands, 165
Profunda artery, 175, 186

femoris artery, 198
Promontory of the sacrum, 90
Pronator quadratus, 182, 183

radii teres, 182, 183
Prostate gland, 164, 165
Proteins, 11, 26, 33, 140, 144,

147, 148

Protoplasm, 12, 13
Psoas magnus, 189, 190

parvus, 190
Ptosis of liver, 152

of upper lid, 74
Ptyalin, 61, 136
Pubes, 161, 163
Pudic artery, 168
Pulmonary artery, 106, 110

circulation, 110

valves, 104

veins, 105, 110
Pulse, 112, 113, 114, 115

216

INDEX.

Pulse, causes, 112

dicrotic, 113

rate, 111, 113, 114
Pupil of eye, 69, 72
Pus corpuscles, 120
Pylorus, 138
Pyramidalis muscle, 134
Pyramids, Malpighian, 156

QUADRATUS lumborum, 134
Quadriceps extensor, 190

RADIAL artery, 108, 185

nerve, 85

Racemose glands, 35
Radius, 178, 179
Rales, 129

Receptaculum chyli, 32
Recti muscles of eye, 67, 72
Rectum, 145, 146
Rectus abdominis, 133, 134

capitis anticus major, 93

femoris, 190

Red corpuscles, 118, 119
Reflex action, 83
Regions, abdominal, 134, 135
Renal artery, 109
Rennin, 140
Respiration, 121, 127, et seq.

center of, 78, 130

effect on air, 129, 130

effect on blood, 130, 131

forced, 128, 129

kinds of, 128

rate, 128

sounds, 129

variations in, 131
Retching, 140
Retina, 68, 69, 70
Rheumatism, 25
Rhomboideus muscles, 93
Rickets, 19, 49, 53, 97, 164, 195

Ribs, 97, 9S

Right lymphatic duct, 31, 32

Rigor mortis, 22,, 23

Rivinus, ducts of, 62

Rodent ulcer, 74

Rods and cones, 69, 70

Rolando, fissure of, 75, 82

Rosary, 97

Round ligament of uterus, 168

Round window, 64, 65

Rupture, 146, 164

of kidney, 158

of liver, 152

of spleen, 154

of urethra, 160

SACRAL nerves, 84

plexus, 84, 85

vertebrae, 90
Sacro-sciatic notch, 163
Sacrum, 90, 161
Sagittal suture, 48
Saliva, 61, 136
Salivary glands, 35, 61, 136
Salpingectomy, 169
Saphenous veins, 109, 199
Sarcolemma, 21
Sarcoma, 173, 177, 11)3
Sartorius muscles, 23, 190
Scalenus muscles, 93, 128
Scaphoid bone, ankle, 195

wrist, 181
Scapula, 173
Scarlet fever, 35
Scarpa's triangle, 190, 198
Schwann, white substance of,

Sciatic nerve, 85, 163, 199
Sclera or sclerotic coat, 68
Scrotum, 165

Sebaceous glands, 35, 40, 41
Sebum, 41

INDEX.

217

Second nerve, 70, 83
Secreting glands, 35
Segmentation, growth by, 12
Semen, 165

Semicircular canals, 64, 66
Semilunar bones, 181

cartilages, 193, 194

valves, 28, 32, 104
Semimembranosus muscle, 191
Semitendinosus muscle, 191
Sense, organs of, 57, et seq.

of hearing, 65

of sight, 70, et seq.

of smell, 55, 57, 58, 61

of taste, 55, 61

of touch, 45, et seq.
Sensory nerves, 82, 83

tract, 82
Septum of nose, 55

deviation of, 58
Serous membrane, 40
Serratus rnagnus, 174
Serum albumin, 1 1

of blood, 117
Sesamoid bones, 19
Seventh nerve, 83
Shin, 194
Shoulder girdle, 171

joint, 185
Sighing, 131

Sight, sense of, 70, et seq.
Sigmoid cavities, 178

flexure, 145, 146
Silent areas in brain, 82
Silver fork deformity, 180
Sinuses, 28, 49, 51, 52, 78, 105
Sixth nerve, 68, 83
Skin, 39, et seq.
Skull, bones of, 48, et seq.
Small intestine, 141, 142, et seq.
Smell, sense of, 55, 57, 58, 61
Smooth muscle, 21, 25

Sneezing, 131

Sobbing, 131

Soft palate, 59, 60, 136

Solar plexus, 87, 153

Soleus, 196

Solitary glands, 142, 145

Sounds, 65, 66

Special senses, 57, et seq.

Speech, 122

center, 82

Spermatic or ovarian artery,
109, 168

cords, 165
Spermatozoa, 165
Sphenoid bone, 48, 52
Sphincter of anus, 146

of pupil, 72

of pylorus, 138
Spina bifida, 91

Spinal accessory nerve, 84, 95,
137

canal, 91

column, 88

cord, 79, et seq.

foramen, 89

nerves, 84, 95
Spine, 87
Spinous process of vertebrae,

Spleen, 153, 154
Splenic artery, 109, 153

flexure, 145, 146

vein, 110, 150
Sprain, 21
Squamous portion of temporal

bone, 51
Stapes, 63

Starches, 12, 136, 144
Steapsin, 144
Stensen's duct, 62
Sterno-cleido-mastoid muscle,

51, 92, 171

218

INDEX.

Sternum, 97
Stimuli, 24
Stomach, 138

arteries, 139

digestion in> 139, 140

glands, 139

position, 138

structure, 139
Stomach teeth, 60
Strabismus, 72
Striated or striped muscle, 21,

23, 25
Stricture of esophagus, 138

of urethra, 160
Sty, 74

Styloid process of fibula, 195
of radius, 178, 179
of temporal bone, 52
of ulna, 178, 179
Subarachnoid space, 76, 79
Subclavian arteries, 94, 9'), 107,

108, 185

veins, 109

Subclavius muscle, 173
Subdural space, 76
Sublingual gland, 56, 62
Submaxillary gland, 56, 62
Succus entericus, 143, 144
Sugar in urine, 151, 158
Superciliary ridges, 49
Supinator brevis, 182, 184

longus, 182, 184
Supraorbital foramen or notch,
49

vessels and nerve, 49
Suprarenal artery, 109

capsules, 36, 154
Suprascapular artery, 94

nerve, 186
Suspensory ligament of lens, 70,

72
of liver, 149

Sutures, 48, 53

coronal, 48

lambdoidal, 48

sagittal, 48
Sweat, composition, 42

functions, 42

glands, 35, 42

nervous control of, 42

quantity, 43
Sylvius, fissure of, 75
Sympathetic nerve, 87, 110,
127, 137, 143, 145, 168

system, 75, 87
Symphysis pubis, 163
Synovial fluid, 20, 34

membrane, 20
Syphilis, 35, 58, 122, 152, 182,

194
Systemic circulation, 105, 106,

107, et seq., 112, 113
Systole, 104, 106, 112

T-FRACTURE, 177, 193
Tablets of skull, 20, 48
Tactile corpuscles, 37, 39, 46
Tarsus or ankle, 195
Taste buds, 61

nerves of, 61

sense of, 55, 61
Tears, 68
Teeth, 27, 60
Temperature of body, 43

regulation of, 43

sensation of, 47

variations in, 44
Temporal bone, 48, 51

muscle, 50, 51, 55
Temporary or milk teeth, 60
Tendo Achillis, 195, 197
Tendons, 15, 23
Tenth nerve, 84
Testes or testicles, 165

INDEX.

210

Third nerve, 68, 72, 83
Thoracic aorta, 99, 107, 109

duct, 31

nerves, 186

Thoracic cutaneous nerve, 100
Thorax, 96

Thymus gland, 36, 124
Thyro-arytenoid ligaments, 122
Thyroid axis, 108

cartilage, 121

gland, 36, 124
Tibia or shin bone, 194
Tibial artery, 198

nerve, 76, 87, 199
Tibialis anticus, 197
Tissues, areolar, 15

bony, 13, 17

cartilaginous, 13

connective, 13, 15

differentiation of, 13

elastic, 15

epithelial, 13

fibrous, 15

muscular, 13

nervous, 13, 36
Tongue, 46, 59, 60

tie, 62

Tonsillitis, 35, 62
Tonsils, 59, 62
Torticollis, 92
Touch, corpuscles, 37, 39, 46

sense of, 45, et seq.
Trachea, 123
Tracheotomy, 123
Transudation of lymph, 33
Transversalis muscle, 133

colli artery, 94
Transverse colon, 145

processes of vertebrae, 89
Trapezium, 181
Trapezius, 93, 171
Trapezoid bone, 181

Triangular cartilage, 57
Triceps, 176, 177
Tricuspid valve, 104
Trifacial nerve, 61, 83
Trochanters, 189
Trochlear surface of femur,

189

of humerus, 175
True pelvis, 163, 164

ribs, 97
Trypsin, 144
Tuberculosis, 35, 122, 155, 159,

168, 182, 193, 194, 196
Tuberosities of humerus, 175

of tibia, 194
Tuberosity of ischium, 163

of radius, 178
Tubuli lactiferi, 100
Tumor albus, 194
Tumors, 100, 175
Tunica vaginalis oculi, 67
Turbinated bones, 48, 53, 54
Twelfth nerve, 84
Tympanum, 51, 63
Typhoid fever, 142, 154

ULCER, 139

Ulna, 177, 178, 185

Ulnar artery, 108

nerve, 85, 175, 186
Umbilical artery, 107

region, 135

vein, 106

Unciform bone, 181
Unstriated or unstriped muscle,

21, 22, 25

Upper extremities, 171, et seq.
Urea, 148, 152, 158
Ureters, 155, 156, 159
Urethra, 159, 160, 165
Urinary apparatus, 155, et seq.
Urine, 156, et seq.

220

INDEX.

Uterine artery, 168
Uterus, 167, 168
Uvula, 59

VAGINA, 168

Vagus or pneumogastric nerves,

84, 110, 111, 130
Valves, 103

aortic, 104

bicuspid or mitral, 104

coronary, 105

Eustachian, 106, 107

ileo-cecal, 142, 145

of lymphatic vessels, 31, 32,
33

of veins, 28

pulmonary, 104

semilunar, 28, 32, 104

tricuspid, 104
Valvulse conniventes, 142
Varicose veins, 109, 113, 199
Vas deferens, 165
Vasa nervorum, 37

vasorum, 29
Vasoconstrictor nerves, 115

dilator nerves, 115

motor nerves, 29, 78, 115
Vascular system, 107. et seq.
Vastus externus, 190

internus, 190
Veins, 27, 28, 29, 109

basilic, 109

deep, 28

gastric, 110, 150

hemorrhoidal, 146

hepatic, 110, 150

iliac, common, 109

inferior vena cava, 105, 109,
150

innominate, 109

intralobular, 150

jugular, 109

Veins, median, 109
cephalic, 109

mesenteric, 110, 150

portal, 110, 150

pulmonary, 105, 110

saphenous, 109, 199

splenic, 110, 150

subclavian, 109

superficial, 28

superior vena cava, 105, 109

umbilical, 106

valves, 28

varicosity, 109, 113, 199
Vena cava, inferior, 105, 109,

150

superior, 105, 109
Venae comites, 27, 113
Ventricles of brain, 75, 79

of heart, 103

Vermiform appendix, 145
Vertebra prominens, 91
Vertebras, 88, et seq.
Vertebral arteries, 77
Vesiculae seminales, 165
Vestibule of labyrinth, 64, 65
Vicarious function of glands,

Villi, 142

Viscera, abdominal, 135, et seq.
Visual center, 81
Vital capacity, 129
Vitreous humor, 70
Vocal cords, 122
Volvulus, 146
Voluntary muscle, 21, 23
Vomer, 48, 55
Vomiting, 140
Vulva, 169

WHARTON'S duct, 62
White corpuscles or leucocytes,
27,33,34,119,120

INDEX. 221

White substance of Schwann, Wrist, 180

37 joint, 185

matter of brain and cord, 75, Wry neck or torticollis, 92

76, 78, 80, 81 YAWNING, 131
Willis, circle of, 78, 108

Wisdom teeth, 60 ZYGOMATIC process of temporal

\\ormian bones, 19, 49 bone, 51, 54

SAUNDERS' BOOKS
FOR NURSES

PAGE

Aikens' Clinical Studies for Nurses 3

Aikens' Hospital Management 3

Aikens' Primary Studies for Nurses 3

Aikens' Training School Methods and the Head Nurse . 3

Beck's Reference Handbook for Nurses 4

Boyd's State Registration for Nurses ... 4

Davis' Obstetric and Gynecologic Nursing 5

DeLee's Obstetrics for Nurses 5

Borland's Medical Dictionaries 7, 8

Fiske's Anatomy and Physiology for Nurses 4

Fowler's Operating Room and the Patient ... . . 4

Friedenwald and Ruhrah on Diet 6

Galbraith's Four Epoch's of Woman's Life 6

Galbraith's Hygiene and Physical Training for Women 6

Grafstrorn's Mechanotherapy (Massage) 8

Griffith's Care of the Baby 8

Hoxie's Medicine for Nurses 8

Lewis' Anatomy and Physiology for Nurses

Macfarlane's Gynecology for Nurses 5

Manhattan Hospital Eye, Ear, Nose and Throat Nursing 6

McCombs' Diseases of Children for Nurses 7

McKenzie's Exercise in Education and Medicine .... 5

Morris' Essentials of Materia Medica 8

Morrow's Immediate Care of Injured 8

Nancrede's Essentials of Anatomy 8

Paul's Materia Medica for Nurses 8

Paul's Nursing in the Acute Infectious Fevers = . . . . 8

Pyle's Personal Hygiene 8

Stoney's Bacteriology and Surgical Technic 2

Stoney's Materia "Medica for Nurses 2

Stoney's Nursing 2

Wilson's Reference Handbook of Obstetric Nursing . . 7

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