presented to

library

of tbe

of Toronto

The 0-nt^

OF KICUO HEALTH fJ'J

OF TORONTO

ANATOMY AND PHYSIOLOGY

FOR TRAINING SCHOOLS AND OTHER
EDUCATIONAL INSTITUTIONS

BUNDY

TEXT-BOOK

OF

ANATOMY AND PHYSIOLOGY

FOR TRAINING SCHOOLS AND OTHER
EDUCATIONAL INSTITUTIONS

BY

ELIZABETH R. BUNDY, M. D.

MEMBER OF THE MEDICAL STAFF OF THE WOMAN'S HOSPITAL OF PHILADELPHIA; GYNECOLOGIST

NEW JERSEY TRAINING SCHOOL, VINELAND; FORMERLY ADJUNCT PROFESSOR OF

ANATOMY, AND DEMONSTRATOR OF ANATOMY IN THE WOMAN'S MEDICAL

COLLEGE OF PENNSYLVANIA; FORMERLY SUPERINTENDENT

OF CONNECTICUT TRAINING SCHOOL FOR NURSES

NEW HAVEN, ETC.

FOURTH EDITION
REVISED AND ENLARGED

WITH A GLOSSARY AND 243 ILLUSTRATIONS
46 OF WHICH ARE PRINTED IN COLORS

PHILADELPHIA

P. BLAKISTON'S SON & CO.

1012 WALNUT STREET

COPYRIGHT, 1906, BY P. BLAKISTON'S SON & Co.

PHINTED, 1906.
REPRINTED, 1907, 1909, 1910, 1911.

SECOND EDITION.
COPYRIGHT, 1912, BY P. BLAKISTON'S SON & Co.

PRINTED, 1912.

REPRINTED WITH CORRECTIONS, 1913.
REPRINTED SEPTEMBER, 1913.

THIRD EDITION.
COPYRIGHT, 1914, BY P. BLAKISTON'S SON & Co.

PRINTED, 1914.
REPRINTED WITH CORRECTIONS, OCTOBER, 1914.

REPRINTED.

FOURTH EDITION.

COPYRIGHT, 1916, BY P. BLAKISTON'S SON & Co.

PRINTED, 1916

REPRINTED, NOVEMBER, 1916.

REPRINTED, MAY, 1917.

REPRINTED, AUGUST, 1918.

REPRINTED, MARCH, 1919.

X 11 K M A !• I. K ] • H K S S Y « > K K. !•

PREFACE TO THE FOURTH EDITION

The fourth edition of this book, like the two preceding ones,
has been prepared with the hope that by certain changes and addi-
tions, it will meet the still increasing demand for a text-book which
shall present the subject of Physiology as well as Anatomy, in a
manner both practical and available to the student.

To include these two large subjects under one cover, with the
necessary brevity and still with sufficient clearness, is a task with
difficulties of its own, but it is undertaken with the earnest en-
deavor to meet the demand created by present requirements as
well as may be with the inevitable problem of selection or omission,
which, however carefully considered, must remain a matter of
judgment and experience.

The plan has been adopted in the descriptions — to emphasize
those characteristics which are most essential and which may be
most readily grasped and, by reason of practical application,
remembered.

The original purpose of the author to provide a special text-
book of Anatomy — still remains in effect, since only by means of
a knowledge of structure -and form can an understanding of use
or function be reached.

The student is referred to the Glossary for the meaning of
unfamiliar terms, and to the lines of smaller type for various par-
ticulars which may be found useful as experience indicates the
need for reference.

The original illustrations drawn for this book are all retained
and several new ones from other sources are added.

Again the author desires to express appreciation of suggestions
and kind words from officials of schools where the book is in use.

PHILADELPHIA ELIZABETH R. BUNDY.

PREFACE AND DEDICATION TO FIRST EDITION

The pupil-nurse in a training-school has very few hours at com-
mand for the study of text-books, but it is hoped that she may
find in this "Anatomy for Nurses" an aid to the acquirement of
that knowledge of the human body which is essential to the full
understanding of her important duties.

In preparing a book of this kind, the inevitable difficulty of
selection, when dealing with a subject of such magnitude, is at once
manifest. What appears from one point of view to be of minor
interest, is from another paramount in importance; while in truth,
no detail is of itself insignificant.

The author trusts that in the present work such matters as are
not available for immediate use in the hospital ward may still be of
value, to meet the growing need of the graduate-nurse as she finds
herself developing with the practice of her profession. It was, in
part, to meet this frequently expressed need that the work was

undertaken.

*********

Concerning the use of anatomic terms, indications point to the
general adoption of the nomenclature accepted by the German
Anatomical Society at the meeting of 1895, in Basle, Switzerland.
The B. N. A., as it is called, .will soon be in use among the younger
physicians at least; therefore, many of the terms belonging to it are
here introduced, and several tables are given which include names
not found in the text.

The author gratefully acknowledges her indebtedness to Dr.
Marie L. Bauer for valuable aid in the preparation of the book,
and to Drs. Frances C. Van Gasken and J. William McConnell
for assistance in the reading of proofs and for helpful suggestions.

The original illustrations, most of which are printed in colors,
are drawn by Chas. F. Bauer.

To the members of the nursing profession, with cherished recol-
lections of labors and responsibilities shared, this Text-book of
Anatomy is dedicated.

ELIZABETH R. BUNDY.
vii

CONTENTS

INTRODUCTORY

PAGE

Plan of study; anatomic terms; muscle, nerve, and connective tissues; epithelial
tissues; gland structure; serous and mucous membranes; processes included
in metabolism of the body; chemical elements and symbols i

CHAPTER I
BONE TISSUE AND BONE CLASSIFICATION. ARTICULATIONS

Chemical composition of bone; structure of osseous tissue; marrow; medullary
and nutrient canals; shapes and surfaces; periosteum; ossification; divisions
of the skeleton; joint movements; remarks n

CHAPTER II
BONES AND ARTICULATIONS OF THE SKULL

Bones of the cranium; sutures and fontanelles; bones of the face; the mandibular
joint; the skull as a whole; four larger fossae of the skull; the teeth; dentition;
care of the teeth; clinical and obstetric notes 20

CHAPTER III
BONES AND ARTICULATIONS OF THE SPINAL COLUMN AND TRUNK

The vertebrae; ligamenta flava; ligamentum nucfuz; movements of spinal column; '
spinal curves; bones and articulations of the thorax; the pelvic girdle; sacro-
sciatic ligaments; dorsal and ventral, or neural and visceral cavities; clinical
and obstetric notes 39

CHAPTER IV
BONES AND ARTICULATIONS OF THE EXTREMITIES

Bones of the upper extremity; pronation and supination; bones of the lower
extremity; patella; Y -ligament, crucial ligaments; arches of the foot; com-
parison of extremities; articular nerves; clinical and surgical notes; special
notes 54

CHAPTER V
COMPLETION, REPAIR AND PHYSIOLOGY OF BONES

Completion of long bones; the skeleton at different ages; bones in infancy; green-
stick fracture; rachitis; spina bifida; process of repair; physiology of bone
tissues; surgical and special notes 75

ix

\ CONTENTS

CHAPTER VI

THE CONNECTIVE TISSUE FRAMEWORK AND SKELETAL MUSCLE

SYSTEM

Fascia, deep and superficial; inguinal ligament; bursae; structure of muscles;
tendon and aponeurosis; origin and insertion; muscles of expression, of neck
and thorax; abdominal muscles and linea alba; sheath of rectus, semilunar
and transverse lines. Diaphragm; surgical and clinical notes; special points . 80

CHAPTER VII
MUSCLES OF THE EXTREMITIES

Structure and action of muscles of upper extremity; axillary space; pronators and
supinators; vaginal synovial membranes; annular ligaments; palmar fascia;
muscles of lower extremity; popliteal space; annular ligaments; physiology
of muscle tissue; muscle tissue a source of heat and electricity; tetanus;
cramp ; f atigue ; clinical notes; special points; classification by action. . . . 101

CHAPTER VIII
THE ORGANS OF DIGESTION .

Alimentary tract or canal; glands of digestive apparatus; enzymes; saliva, alka-
line; the stomach; gastric juice, acid; the intestine; intestinal fluids, alkaline;
villi; ileo-colic valve; cecum and appendix; rectum and anal sphincters;
peristalsis; liver and gall bladder; bile; the porta; notes, clinical and surgical . 130

CHAPTER IX t
PHYSIOLOGY OF THE DIGESTIVE ORGANS. FOOD. ABSORPTION

Four classes of foods in dietary; air as food; food combination; reasons for cook-
ing food; digestion, mechanical and chemical; mastication, insalivation;
gastric digestion (acid), chyme; intestinal digestion chyle; peristalsis; absorp-
tion; clinical notes 153

CHAPTER X
THE BLOOD AND CIRCULATORY ORGANS

Blood-corpuscles or cells. Erythrocytes and leucocytes; ameboid movements,
diapedesis; plasma (alkaline); normal saline solution; arteries, capillaries,
veins; the heart; chambers and valves of heart; endocardium; systole and
diastole; the pulse; pericardium; course of blood through the heart; innerva-
tion of the heart; surg ical and clinical notes; important notes 171

CHAPTER XI '
THE CIRCULATION OF THE BLOOD

Pulmonary vessels; aorta and branches; arteries of the head, of the upper ex-
tremity; palmar arches; thoracic, abdominal and pelvic arteries; arteries of
the lower extremity; veins, deep and superficial; jugular veins; azygos veins;
superior vena cava; inferior vena cava; portal circulation; fetal circulation;
collateral circulation ; clinical and surgical notes 187

CONTENTS xi

Important functions of the blood; coagulation; formation of fibrin; coagulation-
time; phagocytosis; opsonins and opsonic index; antibodies; hypodermo-
clysis; transfusion; osmosis; blood pressure; hemorrhage and control of hem-
orrhages; clinical notes', important notes 213

CHAPTER XIII
THE LYMPH SYSTEM

Lymph spaces, capillaries, and vessels; lymph, origin; lymph glands or nodes;
edema, effusion; thoracic duct; right lymphatic duct; principal nodes;
the lymph stream; hyperemia, metastasis; physiology of lymph system;
clinical notes 221

CHAPTER XIV
THE RESPIRATORY ORGANS AND RESPIRATION

The respiratory tract; the nose, nares and choanae; the larynx; trachea, bronchi
and bronchial tubes; ciliated epithelium; air cells; the lungs; the pleurae;
respiratory movements; physiology of respiratory organs; ventilation;
respiration and heat production; modifications of breathing; clinical notes. 231

CHAPTER XV
ELIMINATION

Organs of elimination; the kidney; structure of the kidney; urinary bladder; ure-
thral caruncle; physiology of the kidney; urine; excretion of urine; quantity
and variations; importance of the process; nephritis; albuminuria; renal casts;
malposition of kidney;1 floating kidney 244

CHAPTER XVI
ELIMINATION (Continued)

The skin; structure of the skin; layers; epidermis and derma, or cuticle and
corium; papillae; vascularity of skin; elasticity; sensibility; panniculus adipo-
sus; glands of skin; appendages; hair; nails, structure of; physiology of skin;
protective; excretory; organ of sense of touch; importance of perspiration;
evaporation; diaphoresis 253

CHAPTER XVII
MAMMARY GLANDS. DUCTLESS GLANDS OR ENDOCRIN SYSTEM

Structure of mammary gland; milk; colostrum; mammary abscess; ductless
glands and internal secretions or autocoid substances; hormones, chalones;
the spleen, structure and blood supply; leukemia; the pancreas structure
and blood supply; adrenals, adrenalin; thyroid body; cretinism; thymus
body an infantile structure; pituitary body or hypophysis; chromaffm tissues. 260

xii CONTENTS

CHAPTER XVIII
METABOLISM \

Secretion and secreting organs; excretion and excreting organs; general metabo-
lism; uses of food; values in metabolism; calorific value; diet charts; influ-
ences effecting metabolim; animal heat; heat production; heat dissipation;

range of normal temperature; preservation of heat 269

</

CHAPTER XIX
THE NERVE SYSTEM

Two divisions of the nerve system, cerebro-spinal and sympathetic; the neuron,
cell body and nerve fiber; cerebro-spinal division; gray and white nerve
tissues; nerve centers; spinal cord and membranes; structure of spinal
nerves; surgical and clinical notes 277

CHAPTER XX
THE SPINAL NERVES

Anterior and posterior divisions; the cauda equina; cervical plexus, phrenic
nerve; brachial plexus, radial, ulnar and median nerves; lumbar plexus,
femoral nerve; sacral plexus, sciatic nerves 284

CHAPTER XXI
THE BRAIN AND CRANIAL NERVES

Structure of brain, cortex and fibers; fissures; ganglia; internal capsule; cere-
bellum; medulla oblongata; pons; crura; ventricles of brain; membranes of
brain; cranial nerves; physiology of brain and cranial nerves; cerebral
localization, surgical and clinical notes 299

CHAPTER XXII
THE SYMPATHETIC DIVISION OF THE NERVE SYSTEM

Vertebral ganglia; cardiac and splanchnic nerves; cardiac and celiac (solar)
plexuses; semilunar ganglia; functions of sympathetic nerves; vasomotor
and reflex, presiding over visceral action; functions of nerve system as a
whole; Important notes; Summary 316

CHAPTER XXIII
THE SPECIAL SENSES

General and special sensation; the sense of smell, olfactory region; the sense of
touch, touch corpuscles; the sense of taste, taste buds; the sense of hearing,
external ear and auditory canal; middle ear or tympanum and auditory
tube; internal ear or labyrinth; acoustic nerves 325

CONTENTS . xiii

CHAPTER XXIV
THE SENSE OF SIGHT. THE VOICE

The sense of sight; structure of eyeball; myopia; hyperopia; astigmatism; range
of accommodation; eyelids, lacrimal gland; associated movements; the
voice; vocal cords; organs of speech 335

CHAPTER XXV
THE PELVIC ORGANS

Organs of male pelvis; of female pelvis; the uterus; uterine or Fallopian tubes;
the ovaries, ovulation; corpus luteum; menstruation; the menopause; the
vagina and infra- vaginal portion of cervix uteri; the pudendum; the peri-
neum; the testes and spermatic cord; peritoneum of pelvis; impregnation;
decidual membranes; placenta; pregnancy; the lochia 346

CHAPTER XXVI
A BRIEF STUDY OF IMPORTANT REGIONS

The head; the neck; thorax and thoracic viscera; abdomen, abdominal viscera
and peritoneum; the ischio-rectal fossa; the axillary space; the ante-cubital
space; Scarpa's triangle or the femoral trigone; Hunter's canal or the ad-
ductor canal; the popliteal space; the inguinal rings and inguinal canal;
the femoral rings and femoral canal; hernia; the extremities compared;
review notes; points for compression of larger arteries of the body 360

CHAPTER XXVII
REFERENCE TABLES

The systemic arteries; names of systemic arteries and veins according to the

B.N. A. ..."..I.:/ 379

Glossary 389

Index 401

ANATOMY AND PHYSIOLOGY

INTRODUCTORY

Anatomy deals with the structure of the body in its different
parts; physiology teaches the uses or functions of those parts.

PLAN OF STUDY

We shall study first the framework of the body — the bones
which give support to all other structures, with the joints by
which they are held together, either loosely or firmly; and the
muscles by which they are moved and still further connected.

Afterward will be presented the organs or viscera (which are
enclosed in the two general cavities formed by the bones and
muscles) with their nerve supply, and the system of vessels by which
the entire body receives its nutriment. We shall see that all
these parts are wrapped in delicate connective tissue, and held
in place by bands and sheaths of the same substance. The mus-
cles are stretched upon the bones, the firm layers and partitions
of deep fascia bind them in place, the wrapping of superficial
fascia keeps them warm and flexible, and the skin or integument
makes an elastic and sufficient covering for the whole.

The study of the nerves by which these structures receive
their stimulus, and the action and interaction of the various
parts, will follow.

The organs of the special senses receive attention, and the last
section is devoted to a review of the several regions of the body
which, it is hoped, will prove interesting and profitable.

ANATOMIC USE OF TERMS

The anatomic position is that with the face toward the ob-
server and the palms turned forward, and the terms anterior,
posterior, right, left, etc., are to be understood with this position

2 ANATOMY AND PHYSIOLOGY

in mind. Thus, the anterior surface of the hand is always the
palm; and, if we speak of any part as situated to the right we
mean that it is nearer to the right side of the body which we are
studying (which for convenience we will call the "subject"),
but it has no relation whatever to the right side of the student.
Of course the words superior and inferior are easily understood,
but the use of the words medial and lateral (formerly internal
and external) requires special mention. Imagine a line drawn
through the middle of the head and trunk and striking the floor
between the feet, thus dividing the body into right and left
halves. This is called the median line. Any part or surface of
one-half of the body is said to be medial to another part if it is
nearer the median line while in the anatomic position, or lateral
to another part if it is farther from the median line.

All-of these terms once applied to a part of the body belong to
it always. For example, the little finger is always medial to the
others and the great toe is likewise medial, because these relations
are established once for all while the subject is in the anatomic
position. Likewise, the palm is the anterior surface of the hand
even if it be temporarily turned backward.

The words exterior 'and interior are applied to the parts of the
body which are on the surface or within, respectively.

Proximal means nearer to the head; distal, farther from the
head. Thus we may speak of the proximal end of the finger, or
the distal end of a toe, or the proximal end and distal end of an
arm or a leg.

Certain words have been so long applied in a special sense in
connection with anatomic relations and physiologic processes
that usage has made them technical, that is, they have come to
possess a professional meaning.

Hilum (literally a little thing) is applied to a place on the
surface of an organ; a depression usually, where the vessels and
nerves enter and leave it. Thus, we see the hilum of the kidney,
of the lung, of the spleen. The hilum is always found on the
medial or most protected surface of an organ. (In the case of the
liver it is on the inferior surface and is called the porta or gateway.)

Sivus (literally a hollow or indentation) is applied in anatomy
to a hollow or enlarged space within an organ, containing either air
or fluid. Air sinuses are hollow spaces (almost enclosed), con-

TECHNICAL USE OF TERMS 3

nected with the nasal passages; these are cavities in the cranial
and facial bones. Lymph sinuses are the spaces within lymph
glands. They contain lymph (in some glands — blood}. Sinuses
containing fluid are large channels in the outer membrane of the
brain — containing venous blood. Other blood sinuses are found in
the heart. The sinus of the kidney is the hollow which is reached
through the hilum which leads into it; this contains urine. In
surgery a sinus is a narrow abnormal channel through the
tissues (usually lined by or connected with an ulcerating surface).
Center and periphery are so used (technically) in connection
with the nervous system. The center is the cell or cells to which
a nerve must belong and be connected with in order to be active.
It need not necessarily be in the middle of a part — some of the
most important centers are on the surface of the brain. The
periphery is the location of the extremity of the nerve. Literally
it signifies the outer boundary or the outside of a thing, but when
used in connection with a nerve it refers to the end farthest from
the cell or center, whether within or without the body.

Centrifugal nerves transmit from center to periphery (they are efferent).
Centripetal nerves transmit from periphery to center (they are afferent).
Efferent vessels carry blood from organs; afferent vessels carry blood to
organs.

Stimulus in physiology signifies any agency which causes a
tissue or an organ to .perform its function. A natural stimulus is a
'normal exciting cause and leads to normal action or function.

An element is, in chemistry, a substance which cannot be
divided into other substances. The most important elements in
the human body are comparatively few. They will be referred to,
sometimes by name, sometimes by symbol. By agreement,
certain letters stand for certain elements (usually the initials of
their Latin names).

0 is the symbol for Oxygen

H is the symbol for Hydrogen

N is the symbol for Nitrogen

C is the symbol for Carbon

S is the symbol for Sulphur

Fe is the symbol for Iron (Ferrum)

P is the symbol for Phosphorus

K is the symbol for Potassium (Kalium)

Na is the symbol for Sodium (Natrium)

4 ANATOMY AND PHYSIOLOGY

(Combinations frequently used are CC>2 for carbon dioxide or
"carbonic acid gas," H20 for water.}

Food principles are simple or compound substances, composed
of one or several elements. They are broadly classed as, i. con-
taining nitrogen, nitrogenous, 2. without nitrogen, non-nitrogenous,
and 3. containing only mineral substances.

TISSUES AND MEMBRANES OF THE BODY

The simplest form of living matter is protoplasm. A living cell
may be nothing more than a definite quantity of protoplasm
(called cytoplasm or bioplasm] or it may be more complex, having
a nucleus, when it is said to be nucleated, and it may have a
nudeolus within the nucleus. A nucleated cell is capable of form-
ing new cells by the division of its substance, the division always
beginning in the nucleus.

Sometimes the cell is enveloped by a thin membrane called the cell wall.

Ifi

FIG. i. — CONNECTIVE-TISSUE
BUNDLES OF VARIOUS THICK-
NESSES OF THE INTERMUSCULAR
CONNECTIVE TISSUE OF MAN.
X 240. — (Lewis and Stohr.}

la

super-
posed
layers

FIG. 2. — ADIPOSE TISSUE. — (Lewis
and Stohr.)

Tissue. — Any collection of cells held together by intercellular
substance is a tissue. The various tissues of the body are com-
posed of cells (and intercellular substance) which are developed in
special ways; for example:

Muscle tissue is composed largely of cells which are highly
developed in the power to contract. Contractile tissues (list, p. 83).

CONNECTIVE TISSUE 5

Nerve tissue, of cells which are particularly sensitive to
special kinds of stimulus.

Connective tissue is the fibrous soft framework of the entire
body — the connecting structure by means of which all of its parts
are held together. (Fig. i.)

Under this heading are included the following varieties:
Fibrous tissue, a form of connective tissue containing slender

white fibers, closely packed together.
Areolar tissue, containing the same kind of fiber cells loosely

woven into a network (often called cellular tissue).
Adipose tissue, a variety of areolar tissue with cells containing
fat. (Fig. 2.)

FIG. 3. — ELASTIC FIBERS. Xs6o. Very thick elastic fibers/, from ligamentum
nuchaeof ox; b, connective-tissue bundles. — (Lewis and Stohr.)

Elastic tissue, a form of connective tissue containing many
elastic fibers, pale yellow in color. (Fig. 3.)

Osseous tissue, composed largely of cells having the power to
utilize mineral substances of the blood in the formation
of bone. (The intercellular substance is filled with min-
eral matter.) (Figs. 7 and 8.)

Cartilage, a form of connective tissue with firm white elastic
substance (intercellular substance) between its cells.
Many cartilages are covered with a thin membrane
called perichondrium, similar to the periosteum of bones
(see page 13).

ANATOMY AND PHYSIOLOGY

The principal varieties are:

Hyaline cartilage which has few cells and much intercellular sub-
stance. (Fig. 4.)
While fibro-cartilage which contains many white fibers, giving to it

additional strength.

Yellow or elastic fibro-cartilage which contains elastic fibers giving ad-
ditional elasticity.
Note.— Most bones are formed in cartilage. (See Ossification, page 14.)

i Epithelial tissue forms the surface layers

of the body both within and without. It is
^ G composed of layers of cells resting upon a base
-. of the simplest possible substance, which holds
the cells together and which bears vessels and
jr> nerves for their use. The form of epithelial
- cells varies with their location and use or func-
tion. (Fig. 5.)

CARTILAGE.— tSfr.) The epithelium oj the exterior of the body is
formed by flattened cells, arranged in few or
many layers according to the degree of friction or pressure to
which the skin of the part may be exposed. The covering thus
formed varies therefore in thickness, from that of the delicate
covering of the lips to the tough sole of the foot.

FIG. 5. — EPITHELIAL CELLS OF RABBIT, ISOLATED. Xs6o. i. Squamous cells
(mucous membrane of mouth). 2. Columnar cells (corneal epithelium) . 3. Columnar
cells with cuticular border s (intestinal epithelium). 4. Ciliated cells; h, cilia
(bronchial epithelium). — (Lewis and Stohr.)

The epithelium of interior surfaces is quite different. Its cells
may be flattened, spherical, cuboid or columnar in shape and it is
always moist. (All body surfaces are epithelial surfaces.)

In the lining of the air passages the epithelial cells are ciliated, that is,
they bear tiny hair-like projections of their substance called cilia, which are
in constant waving motion, always in the same direction, sometimes slow,
sometimes rapid. (See p. 235.)

EPITHELIAL TISSUES . 7

In the digestive organs the epithelial layer plays an important part in the
formation of digestive fluids, and also in the absorption of digested food.

In the lining of closed cavities it -assists in the formation of the fluids which
they contain (example, the pleura).

Included under this heading are (with brief notes of functions) :
Gland tissue, where a layer of cells has the power to form
a special substance from the blood. (Adenoid tissue
resembles gland tissue.) (See p. 8.)

Mucous membranes, which line all interior surfaces to which
air has access. Their special cells produce a clear thick
fluid called mucus which keeps the surfaces moist.

Serous membranes, which line the closed cavities of the body.
They are themselves closed sacs containing a clear thin
fluid called serum which prevents the surfaces from
rubbing together.

Synovial membranes, which line the interior of movable joints;
they contain a thick fluid called synovia which like serum
prevents friction.

The epithelial lining of the heart and blood-vessels, serous membranes,
and lymph vessels, is called endothelium.

Clinical notes. — Mucous membranes are well supplied with blood-vessels
and bleed freely when wounded, as seen in operations upon the nose and
throat.

An accumulation of serum- in the large serous membrane of the abdomen
causes the condition called asciles (a variety of dropsy).

The processes of secretion and excretion are carried on through
epithelial cells. (In specialized epithelial tissues.)

Secretion is the process of separating substances from the blood
(generally in fluid form). Such substances if useful to the body
are called secretions; if they are waste matters to be thrown off or
eliminated, they are called excretions.

Secreting organs — mucous and serous membranes, all glands.

Excreting organs — lungs, kidneys, liver, cutaneous glands.

To summarize the functions of epithelial tissues — they are
protective, secretory, excretory, absorptive.

An organic substance is a substance formed by living cells,
whether they are single or arranged together in organs. Organic
substances disappear in burning. Inorganic substances are mineral.

8 ANATOMY AND PHYSIOLOGY

An organ is any part of the body designed for a special func-
tion or use; it may be composed of several kinds of tissue. An
organ in the interior of the body (internal organ) is called a
viscus (pleural, viscera). Examples, heart, lungs.

A system is composed of a number of organs of similar structure.
Examples, the muscular system, the nervous system.

An apparatus is composed of a number of organs of like or
different structures, so arranged and associated that their action
together will serve a special purpose. Example, the digestive
apparatus.

Metabolism. — This term is used to express in one word the
related processes of building up and breaking down which are
constantly going on in all living cells.

The cell appropriates materials and combines them to perfect
itself; in the exercise of its function it uses up some portion of its
substance and so must be again built up, to be again pulled apart
— in endless repetition.

Cell action in some tissues results principally in liberating heat and in
body movement, as in muscles. In others it forms new compounds for other
cells to use — for example> the liver cells form glycogen; the gastric glands
secrete gastric juice, etc. Again, certain cells combine waste matters to get
them into shape for other organs to excrete, for example, the formation of
urea in the liver. In this way food materials are used for different purposes
and worked over in different tissues until waste alone remains.

These examples (and many more which might be given) illustrate the
metabolism which is constantly taking place in the body, and which will
often be referred to in the text. (See pp. 166, 271.)

Structure of Glands: Since gland tissue is so important
a factor of vital processes, a further description is warranted.
It has already been stated that the epithelial layer is the active
agent in the formation of new substances out of material derived
from the blood. For the performance of this function, the
epithelium is disposed in organs called glands.

The simplest gland is either a small lube, • or a sac. The
tubular gland may be divided into two or more portions forming
a compound tubular gland. Tubular glands exist in the stomach,
intestines, skin, etc.; in the skin they are coiled or convoluted at
the extremity. (See Fig. 166.) A modification of the saccular
gland is one which is composed of many small sacs arranged like

GLAND TISSUES 9

a bunch of grapes upon their stem — racemose gland. The salivary
and pancreatic glands resemble this form.

The secretion of a true gland is discharged through a duct
which opens upon some surface, either of the exterior or the in-
terior of the body — for instance, the sweat glands open upon the
skin, the gastric glands open upon the interior surface of the
stomach, etc. All secretions which are discharged through ducts
of glands are called external secretions. (For internal secretions
see page 263.)

Lymphoid tissues are so called because they contain lymph
cells supported in a network of retiform tissue. The faucial or

Excretory duct.

Secretory duct.

Intercalated duct.

End pieces.

FIG. 6 — DIAGRAM. OF VARIOUS FORMS OF GLANDS. — (Lewis and St&hr.)
The arrangement of ducts in D is that of the human submaxillary gland.

palatine tonsils are lymphoid in structure (page 133), as are
also the lingual and thenaso-pharyngeal tonsils (page 135). (Ade-
noids are hypertrophied naso-pharyngeal tonsils.)

Blood and lymph, although quite different in composition from
others, still conform to the definition of a tissue and are called
fluid tissues. They are each composed of an assemblage of small
cells supported by intercellular substance; in this case, the inter-
cellular substance is fluid instead of solid or semi-solid. In blood,

10 ANATOMY AND PHYSIOLOGY

the cells are blood corpuscles; in lymph, they are lymph corpuscles.
The intercellular substances are blood plasma and lymph plasma.
(Other fluids contain chemical substances only, in solution; cells
appear in them incidentally.)

These tissues will be described more at length in Chapters
X and XIII.

CHAPTER I

BONE TISSUE AND BONE CLASSIFICATION
ARTICULATIONS

Bone tissue is conspicuously a hard tissue,
due to the mineral or inorganic substances
which it contains. They are mostly phosphate
and carbonate of lime and form two-thirds of
the weight of an adult bone. The remaining
one-third is composed of organic or animal
substances, consisting of vessels, marrow, bone
corpuscles, and gelatinous matter.

The mineral portion alone may be seen in
a bone which has been burned (thus destroy-
ing the organic substances). This leaves the
bone still hard, but very brittle and easily
crushed. The pale grayish color of a burned
bone is noticeable, the result of the loss of all
the marrow and blood which it contained be-
fore, and which gave it a pinkish tinge.

The organic portion of a bone may be
shown by immersing it in dilute hydrochloric
acid for a few days. The mineral salts will
be thus dissolved out, leaving the flexible and
elastic organic portion which still retains the
shape of the bone. A long bone after the
lime salts are removed in this way is said to be
decalcified, and may be bent and twisted, or
even tied in a knot.

By these experiments it is seen that the
mineral matter gives hardness to a bone,
while the animal matter gives flexibility and
elasticity. The proportions of the two kinds
of substance vary at different ages. The
bones of a child are soft because they have not

This hardness is

J

FIG. 7. — VERTICAL
SECTION OF A LONG
BONE.— (Testut.)

12

ANATOMY AND PHYSIOLOGY

enough mineral matter to make them hard, while the bones of
an aged person are brittle, because they no longer contain suffi-
cient animal matter to keep them elastic.

The hardest part of any bone is at its surface; it is white in
color like ivory, and is called compact bone tissue. The deeper
part is porous, and is therefore called spongy tissue (also named
cancellous tissue, because its appearance suggests lattice work).
(See Fig. 7.)

Compact tissue is most abundant on the shafts of the long
bones, which by their situation in the extremities are exposed to
external violence, and therefore need especial strength for resist-
ance. Since it is important that the bones be slender as well as
strong, these two results are gained by packing the bone tissue as
closely as possible.

Periosteum

Outer ground lamella

Haversian canals

Haversian lamellae

Interstitial lamellae
Inner ground lamellae

Marrow

FIG. 8. — FROM A CROSS-SECTION OF A METACARP OP MAN. X 50. The Haversian
canals contain a little marrow (fat-cells). — (Lewis and Stdhr.)

Cancellous tissue is more abundant in the parts of bones where
extent of surface is desirable. For example, the enlarged ex-
tremities of long bones are composed of cancellous tissue covered
with a thin compact layer; thus they can give attachment to many
tendons and ligaments, while the spongy character of the bone
prevents excessive weight.

The marrow of bones is contained in the spaces of cancellous
tissue (where it is thin and red) and in little canals running through
the bone substance. Under the microscope may be seen small
channels in the compact tissue called Haversian canals, which con-
tain minute vessels and a little marrow. A large canal called the

i

PERIOSTEUM 13

medullary canal runs in the shaft of each long bone, containing
firm yellow marrow and larger vessels.

Articular surface of bone is that portion which enters into the
formation of a movable joint. It consists of a very compact
tissue called the articular layer or articular lamella.

SURFACE MARKINGS OF BONE

Any inequality of the surface of a bone, whether it be an
elevation or depression, or an opening, is called a "marking."
The most prominent elevations often occur where the muscles are
attached to the periosteum (owing partly to the calcification of
these attachments); and the greatest enlargements of bones are
at their extremities, where they form important joints.

A process is a decided projection; the larger processes are called
tuberosities, small ones, tubercles.

A spine is usually a long or a sharp projection.

A crest is a prominent border; it may be rather broad.

A condyle is a rounded articular eminence.

A fossa is a depression or concavity.

A foramen is a hole through a bone.

PERIOSTEUM

There is no such thing as bare bone in the normal state; all
bones are closely covered more or less completely with a strong
fibrous membrane called periosteum. This membrane is essential
to the life of the bone, because many blood-vessels which nourish
it lie in the periosteum until they become divided into minute
branches which then enter the bone tissue.

The articular surface of bone is the only portion which is not
covered with periosteum.

A bruise of sufficient violence will so injure the periosteum that
it no longer serves for the purpose of nutrition, and that area of
bone immediately underneath the injured membrane dies from
want of food — becomes "dead bone" (the process is called
necrosis}. The sensation imparted by a probe which touches
dead bone is that of roughness, and is distinctly different from the
feeling of sound bone with its smooth covering of periosteum.

14 ANATOMY AND PHYSIOLOGY

A similar membrane called endosteum lines the canal in the shaft
of long bones. It bears the "nutrient" artery which, in the cavity
of the shaft, divides into two branches running in the endosteum
toward the two extremities.

The deep layers of the periosteum contain bone-forming cells.
(See OSSIFICATION.)

According to differences of shape and arrangement of their
tissue, bones are classified as long, short, flat, and irregular. A
long bone has always a shaft of compact tissue,
and two enlarged extremities of cancellous tissue
with a thin compact covering. The shaft is hol-
low, containing yellow marrow, this cavity being
called the medullary canal.

A short bone has neither shaft nor extremity;
it is composed of cancellous tissue with a thin
compact covering.

A fiat bone is arranged in layers, two of compact
tissue with one of spongy or cancellous tissue be-
tween them.

An irregular bone conforms to no special defi-
nition.

REMARKS. — In no part of anatomy is it more impor-
tant that the student should learn the structures from
the actual specimens than in the division called osteology.
The bones are to be studied, not the book. It is supposed
that with the bone in the hand the student will use the
FIG. 9. — RIGHT book as a key, by means of which she will become ac-

FEMUR ANTERIOR, quainted with the names of its parts and their uses.

rrSrSa *j£S£- The habit of studying the human body itselj rather than

SES, AND SHAFT OR the description of it cannot be too soon nor too firmly

DiAPHYSis. — established.

(Morns.)

OSSIFICATION

Ossification is the formation of bone from cartilage or mem-
brane by the deposit of mineral substances, mostly salts of lime.
Flat bones develop in membrane; others in cartilage.

OSSIFICATION 15

The deposit of mineral matter begins in small spots, forming
centers of ossification which gradually increase in size until the
entire bone is completed. Long bones have always three centers
at first — one for the shaft, and one for each extremity — others
appearing later, at different dates. (The extremities are named
epiphyses, the shaft being the diaphysis) (see Fig. 9). The
principal parts of a bone are ossified separately, uniting with
each other after all are developed. Ossification begins before
birth in all bones except the coccyx, those of the carpus, and four
in the tarsus; but many bones remain in two or more pieces
during childhood and youth.

The periosteum of bone has an inner layer in which, also, the
process of ossification goes on. Consequently, when it becomes
necessary to remove a portion of bone, if it can be done without
taking the periosteum away the bone will re-form. This has
occurred many times, particularly in the case of the mandible.

The nutrition of bone. — Bones have a free blood supply from
a network of small arteries in the periosteum. One special artery,
larger than the others, enters the nutrient canal which leads to
the interior of the shaft (this vessel is called the nutrient artery).

The skeleton of the body comprises 200 bones, as follows:

In the cranium 8

In the face , 14

In the spinal column 24

In the pelvis 4

In the upper extremities 64

In the lower extremities 60

Ribs 24

Os hyoides i

Sternum. . , i

200

These are joined together or articulated to form the hard,
strong framework of the body — the natural skeleton.

In addition to these, there are four bones in each ear called ossicles, or
"little bones," malleus, incus, stapes and so-called orbicular bone.

i6

ANATOMY AND PHYSIOLOGY

According to their location in the body they are classified as
follows: Bones of the Head and Neck, Trunk, Extremities.

Head

Tarsus

Metatarsus

Phalanges

FIG. 10. — BONY SKELETON. — (Holden.)

The bones of the head form the skull, which supports the face
and the organs of special sense, and securely encloses the brain
within its cavity. The bones of the neck connect the head with
the trunk, and support the tongue and various other structures.

ARTICULATION OF BONES

The bones of the trunk assist to form a cavity, divisible into
three portions — the thorax, the abdomen, and the pelvis.

The bones of the four extremities contribute the solidity and
strength which are necessary for their uses in various positions of
the body.

ARTICULATIONS (ARTHROSES)

Articulations are formed when two or more bones are con-
nected together, or when bone and cartilage are joined. They
may be immovable or movable.

IMMOVABLE JOINTS (SYNARTHROSES)

In these the bones are held to-
gether firmly by fibrous tissue, some-
times by a thin layer of cartilage which
becomes calcified in later life.

The best examples of immovable
joints are found in the skull, where
the flat bones are joined at their edges,
forming sutures. (See page 20, Fig. 12.)

MOVABLE JOINTS (DIARTHROSES)

In these the bones are not closely
joined, but are loosely connected by
ligaments which allow freedom of move-
ment between the surfaces. They are SHOWING
best studied in the extremities, where
all varieties of movable joints are
found.

The essential structures in a movable joint are four in num-
ber: Articular bone, articular cartilage, ligaments, synovial mem-
brane -with synovia.

The surfaces of bone which are to be connected together
(articular surfaces) are made of a specially hard compact tissue
called articular bone. It is smoother than other portions of the
bone and easily recognized by the eye. It has no periosteum, but
is covered by firm white hyaline cartilage — the articular cartilage.

1 1. — ILLUSTRATION
ESSENTIAL STRUC-
IN A MOVABLE JOINT.

(Diagrammatic.)

1 8 ANATOMY AND PHYSIOLOGY

To hold the bones together, bands or cords of white fibrous
tissue are provided, strong and flexible, but not elastic. They
are called ligaments. The ligaments pass from one bone to
the other on every side of the joint, like a capsule, completely
enclosing it, and the capsule thus formed is lined by synomal
membrane, so named because it secretes a fluid called synovia
(the lubricating fluid or "joint-oil") which resembles in appear-
ance the white of egg and prevents friction.

The synovial membrane not only lines the capsule but is
attached to the margins of the articular cartilages.

Seven varieties of movement are allowed by these joints.
They are:

Flexion, or bending.

Extension, or straightening.

Rotation, or rolling.

Circumduction, a free sweeping movement of the distal end
of a limb in a circle.

Abduction, or moving away from a middle line.

Adduction, or moving toward a middle line.

Gliding (which explains itself).

Movable joints are classified according to the movements of
individual joints, or by peculiarities of structure. The most
important are the following:

Class. Motions. Example.

Hinge (ginglymus) Flexion and extension Elbow, Knee.

Ball and socket (Enar-

throsis) In all directions Shoulder, Hip.

Pivot (Trochoides) Rotation within a ring — Head of Radius.

Rotation of ring around a

pivot Atlas and axis.

Arthrodia Gliding Wrist joints.

There are other joints in which motion is so slight that they
are not classed as movable, nor do they possess a^cavity containing
synovia. They have been well described by the term yielding.
In these the bones are usually connected by fibro- cartilage discs.
Examples are found in the joints of the pelvis (page 50) and in
the spinal column (page 42). They are sometimes classified as
slightly movable.

PECULIAR JOINTS 1 9

A variety of ball and socket joint is the condyloid, where the surfaces have
an oval instead of a round outline; they allow all motions except rotation.

Another is the saddle-joint. Each surface has both a concavity and a
convexity and each receives the other. (See page 63, Surgical Note No. 2.)

CHAPTER II

BONES AND ARTICULATIONS OF THE SKULL
The skull includes the cranium and face.

BONES OF THE CRANIUM, 8

. i Parietal... . 2

Frontal i

Occipital i

Temporal 2

Ethmoid. .
Sphenoid. .

Frontal bone (os frontale) . — In the anterior part of the skull,
shaped like a cockle-shell, and consisting of the frontal part, or
forehead, the two orbital parts, and the nasal part. The frontal

CUABELLA

ANTERIOR NASAL
SPINE

GNATHIO

FIG. 12. — THE SKULL. — (Gerrish.)

part (squama frontalis) is flat in structure, and unites above with
the parietal bones. This part is bounded below by a prominent
border forming the two supraorbital margins. At the medial

FRONTAL AND OCCIPITAL BONES

21

third of each margin is a supraorbital notch (sometimes foramen)
for the supraorbital nerve, artery, and vein. Just above the
margins are the superciliary arches, which bear the eyebrows and
mark the position of spaces in the frontal bone called the frontal
sinuses. These sinuses begin to develop at the age of seven years
and grow larger as time advances. They communicate with the
nose, and contain air. The smooth space between the eyebrows
is the glabella.

The nasal part is just below the glabella.

The orbital parts (or plates) of the frontal bone are so called
because they are hi the roof of
the orbits, or eye-sockets; the
space between these parts is
occupied by the ethmoid bone
and is called the ethmoid notch.
Just underneath the lateral part
of the superior margin of the
orbit is a small fossa (the lacri-
mal fossa), containing the lacri-
mal gland, where the tears are
formed.

At birth the frontal bone is
in halves — right and left —
which become united in early
life.

Occipital bone (os occipitale). — At the back of the skull and
consisting of two portions: squamous (scale-shaped) and basal
(Figs. 12 and 21).

The squamous portion (squama occipitalis) is flat in structure,
triangular in shape, and joined to the parietal bones. The most
prominent point on the back of the skull is on this portion, and
is called the occipital protuberance or inion.

The basal portion bends forward, extending far enough toward
the front to form the roof of the throat. This portion presents a
large opening called the foramen magnum (or great foramen),
which transmits the spinal cord*. At the sides of the foramen
magnum are two smooth prominences, called the occipital condyles,
which rest upon the first bone of the spinal column, whereby the
nodding movement of the head is permitted.

FIG. \$. — FRONTAL BONE, SHOWING
THAT IT ORIGINATES IN HALVES. —
(Morris.)

22 ANATOMY AND PHYSIOLOGY

The inner surface of this bone has broad grooves for the transverse sinuses
(lateral sinuses); also one for the sagittal sinus (superior longitudinal sinus).

Temporal bones (ossa temporales). — Right and left; situated
at the sides and base of the skull. (See Figs. 12 and 14.)

Each temporal bone consists of four portions — the squamous,
the mastoid, the petrous, and the tympanic.

The squamous portion (squama temporalis) is flat, and presents
the zygomatic process in the form of a ridge running forward in front
of the ear to the cheek. Below the beginning of this process is the
canal leading into the ear and called the external auditory meatus;

FIG. 14. — PARIETAL, TEMPORAL, AND SPHENOID BONES; POSTERIOR ASPECT.
i, Body of sphenoid bone; 2, 2, greater wing and squamous portion of sphenoid
bone; 3, 3, parietal bones; 4, 4, mastoid process of temporal bones. — (Sappey.)
The occipital bone occupies the space outlined by these bones posteriorly.

just in front of that is the mandibular fossa, where the lower jaw-
bone, or mandible, is joined to the temporal bone (Fig. 12).

The mastoid portion forms the prominence behind the ear and
terminates in the mastoid process, which contains a number of
small cavities, the mastoid cells. They all communicate with
the middle ear, and mastoid disease may therefore follow an
infection of the middle ear.

The inner surface of this portion shows the sigmoid groove for the transverse
sinus.

PARIETAL AND ETHMOID BONES 23

The petrous portion is exceedingly hard, like stone, hence its
name. A slender point of bone, called the styloid process, is seen
on its lower surface; the carotid artery, on its way to the brain,
passes through the carotid canal, which is in this portion.

The petrous bone contains the greater part of the ear; the
internal auditory canal for the auditory nerve, or nerve of hear-
ing, is on its posterior surface (seen within the skull).

The tympanic portion forms the greater part of the external auditory
meatus, or canal.

Parietal bones (ossa parietales). — Right and left, situated at
the top and sides of the head, and so named because they form
the sides or walls of the skull. They are flat in structure, and
nearly square in shape; the four borders are called sagittal,
squamous, frontal, and occipital (Figs. 12 and 14).

At the extremities of the -borders are the angles — the frontal
and occipital angles above, and the sphenoid and mastoid angles
below. The most prominent point on the side of the skull is near
the center of the parietal bone and is called the parietal eminence.

On the inner surface of this bone well-marked grooves are
seen for the middle meningeal artery, and depressions for the
convolutions of the brain.

Ethmoid bone (os ethmoidale). — Situated between the orbits
and, therefore, in the upper part of the nose. (For illustration
see pages 33, 34.)

It consists principally of two lateral portions formed of spongy
bone, and containing the ethmoid cells or sinuses. These portions
are called ethmoid labyrinths. They are in the walls of the nasal
cavity and the cells open into it, therefore they contain air.
The labyrinths are attached to the borders of the horizontal
plate, which is situated in the roof of the nose and perforated for
the passage of the nerves of smell.

The upper part of the nasal septum, which divides the nasal
cavity into two parts, is formed by the vertical plate of the ethmoid,
which hangs from the horizontal plate, and is, therefore, between
the two labyrinths (Fig. 26).

Two of the turbinated bones (superior and middle) project from the
medial surface of the labyrinths (Fig. 25). (For description of inferior
turbinated bone see page 26.)

24 ANATOMY AND PHYSIOLOGY

Sphenoid bone (os sphenoidale] . — Immediately behind the
ethmoid, to which it is joined. Its shape resembles a bat with
the wings spread (Figs. 12 and 14). It consists of a body, wings,
and two pterygoid processes. The body is joined to the ethmoid
in front, and to the occipital behind. It is hollow, and its two
cavities (called the sphenoid sinuses} communicate with the nose.
The wings, two pairs — greater and lesser — extend outward from
the body at about the level of the orbits. The optic foramen,
for the optic nerve, is in the lesser wing.

The processes extend downward from the body, completing
the back part of the sides of the nose.

Note. — The lateral extremities of the greater wings may be seen at the
sides of the skull, between the frontal and temporal bones; the sphenoid is
thus wedged in behind the face, between it and the other cranial bones. (The
name sphenoid signifies wedge-like.)

ARTICULATIONS OF THE CRANIUM

The joints of the cranium are called sutures. Most of them
are formed by the interlocking of irregular edges of the bones held
firmly together by fibrous tissue between them. Sometimes the
edges resemble saw-teeth in form, and then the suture is dentated
or serrated. Sometimes the edges are smooth and overlap each
other, and sometimes one fits between two others; but they are
always immovable. (For illustration, see Fig. 12.)

The sutures which are most important for the nurse to recog-
nize are those formed with three borders of the parietal bones.
The two sagittal (or superior) borders, uniting with each other,
form the sagittal suture; the frontal borders, uniting with the
frontal bone, form the coronal suture, while the occipital borders,
uniting with the occipital bone, form the lambdoid suture.

BONES OF THE FACE, 14

Nasal 2 Palate 2

Lacrimal 2 Inferior turbinated. .. 2

Zygomatic 2 Vomer i

Superior maxillary. . . 2 Inferior maxillary, or

united, form the maxilla. mandible i

Nasal bones (os nasale, sing.). — Right and left. (Fig. 12.)
They are flat in structure and form the bridge of the nose, being

joined to each other in the median line of the face and to the frontal
bone above.

Lacrimal bones (os lacrimale, sing.). — Right and left; small
and thin, situated in the walls of the orbits, just under the ex-
tremity of the supraorbital margin (Figs. 12 and 24). In this bone
is the beginning of the canal in which the lacrimal duct runs con-
veying the tears into the nose, thus preventing them from over-
flowing the eyelids and running down the cheek.

Zygomatic bones (os zygomaticum, sing.). — Forming the promi-
nences of the cheek (Fig. 12). They are especially noticeable
in certain races, as the Chinese, for example, who have high
"cheek bones."

Maxilla (or upper 'jaw-bone). — Situated in the front of the
face, and composed of the two superior maxillary bones joined

Infraorbital foramen

Canine eminence

Articulates with zygo
matic bone

Posterior dental canals

— Tuberosity

FIG. 15. — THE MAXILLA. — (Morris.)

together below the nostrils. It supports the cheeks, helps to form
the nose and also the floor of the orbits. It consists of a body and
several processes.

The body is hollow, the space being called the maxillary sinus
or antrum of Highmore which opens into the side of the nasal
cavity. In the lower border of the body the teeth are imbedded,
the sockets of the large teeth being in the floor of the antrum,
which explains how a diseased tooth may lead to antrum trouble.

The foramen on the surface of the body just below the orbit is called the
infraorbital foramen. It is on a line with the supraorbital foramen of the
frontal bone already mentioned.

26

ANATOMY AND PHYSIOLOGY

Processes. — The frontal process extends upward along the
side of the nasal bone to join the frontal. The palate process
is in the roof of the mouth, the bony part of the roof being called
the hard palate. The alveolar process (or alveolus) is the thick
border of bone in which the upper teeth are fixed. This process
is very spongy and is sometimes broken in extracting a tooth.
The zygomatic process joins the zygomatic bone to form the
prominence of the cheek.

Foramina and in-
cisive suture

Palate process

Palatine foramina
in a palate bone

FIG. 16. — THE HARD PALATE, OR ROOF OF THE MOUTH. — (Morris.)

Palate bones (os palatinum, sing.). — Right and left; shaped like
the capital letter L, and placed behind the maxilla. The upright
portion is in the side of the nose at the back; the horizontal
portion lies in the floor of the nose, being at the same time in the
roof of the mouth, and thus completing the hard palate (Fig. 21).

Inferior turbinated bones (concha nasalis inferior, sing.). —
Right and left; situated in the right and left walls of the nasal
cavity below the superior and middle turbinated bones which
belong to the ethmoid (Fig. 25). Each is composed of a thin plate
of spongy tissue, having one edge rolled under like a shell (concha);
they extend from front to back on the lateral wall of the cavity.

Clinical note. — Hypertrophy (or overgrowth) of the inferior
turbinated bone is a frequent cause of obstruction to proper
breathing.

Vomer. — A thin bone resembling a plowshare in shape, joined
above with the vertical plate of the ethmoid, and below with the

THE MANDIBLE 27

maxilla, thus forming the lower part of the septum of the nose. It
is this part of the septum which is sometimes bent to one side, or
"deflected," and it often presents a "spur" on one of its surfaces.
(The vertical plate of the ethmoid and the vomer together form the
bony septum, Fig. 26.)

Articulates with
ethmoid

Groove for nerve , ^^

• Posterior border
Articulates with
hard palate

FIG. 17. — THE VOMER. — (Morris.)

Mandible (inferior maxillary, or lower jaw-bone, mandibula) . —
The only movable bone in the skull. It consists of a body having
on either side a ramus (or branch) which is attached by ligaments
to the temporal bone

The body is the lower portion, shaped much like a horseshoe
with a thickened border (the alveolus) which bears the lower
teeth.

FIG. 18. — THE MANDIBLE.

i, Body of bone; 2, ramus; 3, symphysis; 4, incisive fossa; 5, mental foramen; 7,
depression for passage of facial artery; 8, angle of jaw; 10, coronoid process; n,
condyle; 12, sigmoid notch; 13, alveolar border: a, incisors; b, bicuspids; c, canines;
m, molars. — (Sappey.)

On each side is an opening called the mental foramen, which is in a line
with the infraorbital and supraorbital foramina, already mentioned.

Each of these three openings transmits an important nerve, artery, and
vein, bearing the same name as the foramen. See Surgical note, p. 308.

The ramus extends upward from the body, and ends in two
processes, one of which is the condyle; it is this condyle which
articulates with the temporal bone to form the temporo-maxillary
joint.

28 ANATOMY AND PHYSIOLOGY

Clinical note. — Dislocation of this joint easily occurs if the
mouth is opened too widely.

The angle of the jaw or mandible, is the posterior extremity of the lower
border. The prominence of the angle differs in different people and at
different ages.

ARTICULATIONS OF THE FACE

The bones of the face are all irregular, and many of them are
very frail. They are fixed by sutures with one exception — that
of the mandible which moves freely. (For description of a
movable joint, see page 17.)

THE MANDIBULAR JOINT

The mandibular joint is a hinge-joint, and the only movable
joint in the skull. The action may be felt in front of the ear.

The bony surfaces are the condyle of the mandible and the
mandibular fossa of the temporal bone. They are covered with

Capsule

FIG. 19. — MANDIBULAR JOINT. — (After Morris.)

cartilage and connected by ligaments forming a capsule, which is
sufficiently loose to allow the condyle to glide freely in the fossa,
back and forth or sidewise, as in opening and closing the mouth
and masticating the food.

Surgical notes. — If the mouth be suddenly opened very
widely, as in hearty laughing, dislocation easily results — that is,

THE CRANIUM 2Q

the condyles glide too far forward and slip in front of the fossa,
making it impossible to close the mouth. To correct this con-
dition (or "reduce the dislocation") press the jaw forcibly down-
ward and backward with the thumbs placed upon the molar teeth.
(First wrap the thumbs with a napkin to protect them, as the
mouth will close suddenly.)

POINTS OF INTEREST IN CONNECTION WITH THE
SKULL AS A WHOLE

. THE CRANIUM

The cranium is a firm, strong case for the brain, composed
largely of flat bones, the layers of these flat bones being called the

B REG MA

ANTERIOR NASAL
SPINE

PHOSTHIO

CNATHIO

BELION

LAMBDA

1NION

FIG. 20. — THE VERTEX AND SIDE OF THE SKULL. — (Gerrish.)

tables of the skull. The innermost table is very brittle and may be
fractured by a blow which does not break the outer one, and
owing to this brittleness it is called the vitreous, or glassy layer.

Observing the illustrations, or better, with the skull in the
hand, the student may trace the frontal, two parietal, and
occipital bones forming the vault of the skull, or the vertex; and at

30 ANATOMY AND PHYSIOLOGY

the sides the squamous and mastoid portions of the temporal
bones and the tip of the great wing of the sphenoid.

Turning the skull upside down, observe the base. In the
median line at the back is the basal part of the occipital bone,
with the foramen magnum and the condyles on either side of it.
In front of that are the body and processes of the sphenoid, and
the roof of the mouth (or hard palate} bounded by the upper
teeth. Tracing forward from the lateral part of the occipital

HP?

FIG. 21. — BASE or SKULL.

i, 2, 3, Foramina and sutures in hard palate; 4, post-nasal spine; 5, nasal septum;
6, 7, 8, 9, 10, ii, 12, pterygpid processes, and markings on sphenoid bone; 13, zygo-
matic arch; 14, spheno-occipital suture; 15, 16, 17, 18, 19, 20, markings on tem-
poral bone; 21, 21, condyles of occipital bone; 22, basal portion of occipital bone;
23, foramen magnum; 24, 25, crest and lines of occipital bone. — (Sappey.)

bone is the petrous portion of the temporal, with its sharp styloid
process and round opening of the carotid canal; and in front of the
temporal is the great wing of the sphenoid. The ethmoid may be
seen through the posterior- nares where the turbinated bones
(better, shell-bones] are all visible.

Numerous openings or foramina pierce the base of the skull,

THE FACE

for vessels and nerves. The jugular foramen is just back of the
carotid canal; through it the jugular vein leaves the skull to pass
downward in the neck. The interior surfaces of all cranial bones
show depressions for the convolutions of the brain.

THE FACE

(See Figs. 20, 24.)

Beginning with the forehead, note the two frontal eminences,
and below these the superciliary arches with the glabella between
them. Still lower, the supraorbital arches, with the nasal notch
between them, to which the nasal bones are attached. Observe

FIG. 22. — SKULL OF NEW-BORN CHILD, FIG. 23. — OCCIPITAL FONTANZLLE.
SHOWING FRONTAL FONTANELLE. — Both cuts show moulding of the head. —
(Edgar.) (Edgar.)

the lacrimal canal at the medial side of the orbit leading to the
nasal cavity. Below the orbit, locate the infraorbital foramen on
the surface of the maxilla and the mental foramen on the body of
the mandible.

Remember that these three foramina transmit three very sensitive nerves,
as follows: — The supraorbital nerve for the Jorehead, the infraorbital nerve for
the cheek, and the mental nerve for the lower lip and chin. (Blood-vessels
bearing the same names accompany these nerves.)

The prominences at the sides of the cheeks are made by the
zygomatic bones. The openings of the nasal cavity are the
anterior nares, within which may be seen the septum, and the
middle and inferior turbinated bones (shell bones)

32 ANATOMY AND PHYSIOLOGY

THE SKULL AT BIRTH

The bones are only partially developed, a considerable space
between them being occupied by membrane (in some places,
cartilage), and the frontal bone is in two pieces.

Fontanelles. — The parietal and Jrontal bones are incomplete
at the angles where their sutures meet, leaving a diamond-shaped
space above the forehead where there is membrane only, and which
is called the anterior or frontal fontanelle. The parietal and
occipital bones also are lacking where their sutures meet, leaving
a triangular soft spot called the posterior or occipital fontanelle,
which is much smaller. These fontanelles are closed as the bones
develop; the occipital in a few months, the frontal before the end of
the second year.

Superciliary
ridge

Glabella

FIG. 24. — THE OKBIT. — (After Morris.)

Obstetric note. — Owing to the fact that the bones are not
firmly jointed, they can be made to overlap and thus adapt the
shape of the child's head to the passage which it must traverse
during birth. This is called the moulding of the head (Figs. 22
and 23).

The four large fossae of the exterior of the skull are the tem-
poral, infratemporal, orbital, and nasal.

The temporal fossa (fossa temporalis}. — The thinnest part

FOSS.E OF SKULL

33

of the skull (Fig. 20). It is bounded by the temporal ridge and
the zygomatic arch, occupied by the temporal muscle, and covered
by a strong membrane, called the temporal fascia, through which
the motion of the muscle may be felt.

Infratemporal (or zygomatic) fossa. — At the side of the skull
below the temporal fossa, from which it is separated by the zygo-
matic arch (Fig. 20). It is covered by the ramus of the mandible,
and occupied by two of the muscles oj mastication, and also by a
number of important arteries, veins, and nerves.

Concha superior
Sphenoidal sinus

Middle meatus

Palate bone
Inferior meatus

FIG. 25. — LATERAL WALL or NASAL FOSSA OR CAVITY. — (Morris.]

Orbital fossa (or orbit). — containing the eye. It is shaped
like a pyramid, the apex being at the back of the fossa. The
large opening on the face is bounded by the margins of the orbit,
having the frontal bone above, the maxilla below, and the zygo-
matic bone on the lateral side.

The orbital plate of the frontal bone is in the roof of the orbit, and the
3

34

ANATOMY AND PHYSIOLOGY

orbital plate of the maxilla in the floor. The lacrimal and ethmoid bones are
in the medial wall; the sphenoid and zygomatic bones in the lateral wall.

The lacrimal canal begins in the lacrimal bone and runs down
into the nose. The optic foramen, for the optic nerve, is at the
apex of the fossa.

Nasal fossa. — Roof formed by nasal and ethmoid bones; floor
by maxillary and palate bones; lateral wall by nasal, ethmoid,

FIG. 26. — THE BONY SEPTUM.
Body of sphenoid immediately be-
hind it. — (Morris.)

EIG. 27. — HYOID BONE, ANTERIOR

ASPECT.

i, i, Anterior or convex surface of
body; 2, 2, greater cornua; 3, 3, junc-
tion of greater cornua with body; 4,
lesser cornua. — (Sappey.)

maxillary, and palate bones; septum by ethmoid and vomer
(Fig. 26).

The openings on the face, or anterior nares, are bounded by the
maxillary and nasal bones, and separated by the vomer. The
openings into the throat or posterior nares are bounded by the
sphenoid and palate bones, and separated by the vomer. Turbi-
nated bones are seen on the lateral walls of the fossae.

Each nasal fossa communicates with four sinuses: the sphenoid, ethmoid,
frontal, and maxillary. The sphenoid sinus opens into the upper and back
part; the ethmoid, frontal, and maxillary (or antrum of Highmore) open at the
side, lower down. The lacrimal canal also opens at the side near the floor.

The nasal fossae are lined with mucous membrane (the
Schneiderian membrane) which is continued into all of the sinuses
and the pharynx.

Clinical note. — Inflammation of this membrane may extend

THE TEETH 35

into any of the sinuses, causing sinusitis. If this occurs in the
frontal region, a dull pain is felt over the eyes; if in the ethmoid
region, a pain at the side of the nose and a change in the sound of
the voice (nasal tone) are noted. The inflammation frequently
extends into the antrum of Highmore.

The sense of smell resides in the upper part of the nose, the
olfactory nerves coming down through the sieve-like plate of the
ethmoid bone in the roof of the fossa.

BONES OF THE NECK

Hyoid (os hyoides).
Seven cervical vertebrae.

The hyoid bone, or os hyoides. — Shaped like the letter U,
situated in front of neck, about on a level with the chin, and sus-
pended by ligaments and muscles from the styloid process of the
temporal bone. The hyoid is not articulated to any other bone.
It consists of a body and four cornua (or horns} , and is designed
to give attachment to the muscles of the tongue, and to others
which connect it to the mandible above and sternum and clavicle
below.

Seven cervical vertebrae. — The seven cervical vertebrae and
their articulations will be described with the spinal column.

THE TEETH

A tooth is composed of dentine or tooth-bone, and consists
briefly of a crown, a neck, and a root.

Crown. ^^ ^_

^ .Root

Cusp-

Neck- 4 -^rf 7 -Pulp
cavity

-Neck

Root— WH M!_ c.ngulum

"Crown

FIG. 28. — A MOLAK TOOTH IN SECTION AND A CANINE TOOTH. — (Morris.)

The crown is the exposed portion and is covered with hard
white enamel. The root (connected with the crown by the neck)
is concealed in the socket of the jaw and is covered with cement.
The shape of the tooth varies from that of the flat incisor or cutting
tooth, to the broad one for crushing and grinding.

36 ANATOMY AND PHYSIOLOGY

The incisors are the front teeth, four in number in each jaw.
They are used for biting and cutting the food.

The cuspids (pointed) or canine teeth are situated next to the
incisors; they also bite and masticate.

The bicuspids (two-pointed) or pre-molars, and the molars are
for purposes of mastication.

The shapes of all are shown in the illustrations.

The teeth are hollow and contain tooth-pulp. This consists of
a delicate meshwork of vessels and nerves entering at the point of
the root, wrapped in connective tissue and filling the pulp cavity.

The upper teeth are imbedded in the alveolus of the maxilla, or
upper jaw; the lower teeth in the alveolus of the mandible, or lower
jaw.

Dentition : the Eruption of the Teeth

The teeth make their appearance in two sets, called temporary
and permanent.

FIG. 29. — THE TEMPORARY TEETH.
The rudiments of the permanent teeth are seen enclosed in the bones. — (Gorgas.)

The temporary teeth are twenty in number; their eruption or
" cutting " usually begins at about the seventh month and proceeds
in following order:

Two lower central incisors at 7 months.

Two upper central incisors at 8 to 10 months.

Two upper lateral incisors at 9 to 12 months.

TEMPORARY TEETH

37

Two lower lateral incisors at 12 to 15 months.

Four first molars, i right, i left in each jaw.... at 12 to 15 months.

Four canines, i right, i left in each jaw at 16 to 22 months.

Four second molars, i right, i left in each jaw., at 24 to 30 months.

Twenty teeth in the temporary set at two and one-half years of age.

Thus, at one year of age the average child will have six teeth;
at two years, sixteen; and the full number before it is three years
old. Many exceptions occur, for example: the dentition of arti-
ficially fed children may be delayed; and it is oftenest late in
children affected by rachitis or " rickets."

The upper canines are known in the nursery as "eye-teeth"; the lower
canines as "stomach teeth."

Clinical points. — "Teething" or "cutting" of the temporary
set occurs while the digestive tract is still in process of develop-
ment and very easily disturbed; therefore special care should be

Incisors

Canine

Preraolar

Molars

Wisdom tooth

FIG. 30. — THE TEETH OF AN ADULT. — (Morris' Anatomy.)

given to the child's diet both as to quality and quantity. Like-
wise, £he always delicate nervous system is at this time most easily
irritated and excitement and fatigue should be avoided. These
two points are equally important.

Meanwhile the permanent teeth are forming (Fig. 30). They
gradually push toward the surface, cutting off the blood supply to
the temporary teeth which become loose and fall out.

38 ANATOMY AND PHYSIOLOGY

The permanent teeth are thirty-two in number. At the age
of six years the first permanent molar ("six-year molar") should
appear; the others follow in order somewhat like the following:

Four first molars, i right, i left, in each jaw. ... at 6 years.

Eight incisors, 2 central, 2 lateral, in each jaw . . at 7 to 8 years.

Eight bicuspids, 2 right, 2 left, in each jaw at 8 to 10 years.

Four canines, i right, i left, in each jaw at 12 to 14 years.

v Four second molars, i right, i left, in each jaw. . at 12 to 15 years.

Four third molars, i right, i left, in each jaw... . at 17 to 25 years.
(The third molars are called "wisdom teeth.")

Thirty-two teeth in the permanent set at twenty-five years of age.

Clinical notes. — Caries, or decay of teeth, is due to bacterial
action. This is favored by the accumulation of particles of food,
the warmth and moisture of the mouth furnishing perfect conditions
for the development of bacteria. Careful cleansing with brush or
dental floss, or both, will prevent this and thus aid in preserving
the teeth. Care is important in the use of brush or floss or
toothpick, not only that the removal of injurious particles may be
well done but in order to avoid wounding the mucous membrane
which covers the gums., thus exposing them to bacterial invasion.

Recession of the Gums. — Any irritation (as by bacteria) of the
gums may be followed by their recession, which exposes the dentine
where it is not protected by enamel.

Sudden changes of temperature, as from hot to cold liquids, is
injurious to the enamel. Acids, as ordinarily taken in food, have
no special action upon the teeth, but sweets may do harm by
their fermentation in a mouth where teeth are not kept clean.

The sockets of the teeth are lined with periosteum (dental
periosteum). It is reflected at the bottom of the socket to the root
of the tooth and covers the cement; this portion is called the
peri-cemental membrane (or periosteum). •

Bacterial invasion of the gums may extend beneath the periosteum, caus-
ing a chronic inflammation with suppuration, called pyorrhea aheolaris.
Often the condition is painful, mastication is difficult and the teeth loosen and
almost fall out of themselves.

CHAPTER III

BONES AND ARTICULATIONS OF THE
SPINAL COLUMN AND TRUNK

The bones of the spinal column are
twenty-six in number. They are irregular
and are arranged as follows, from above
downward:

f 7 cervical in the neck.

24 separate vertebrae | 12 thoracic in the back.

I 5 lumbar in the loins.

i sacrum,
i coccyx.

in the pelvis.

A vertebra consists of a body and an
arch, joined together to form a ring of
bone with a space enclosed called the
vertebral foramen, which is occupied by the
spinal cord. The bodies are composed of
spongy bone, placed one above the other
and held together by discs of fibrocartilage
between them. In this way the solid and
flexible portion of the spine is constructed.

The arch consists of two roots next to the
body, and two lamina which meet at the
back. There are seven processes on the
arch of each vertebra — four articular (two
to form joints with the bone above, two
for the bone below); two transverse (pro-
jecting from the sides), and one spinous
which projects backward. The row of
spinous processes is felt by passing the ringer
down the back in the median line; that of
the seventh vertebra is easily seen, and
this bone is called the vertebra prominens.

39

FIG. 3 i. — VERTEBRAL
COLUMN, LATERAL ASPECT.

1-7, Cervical vertebrae;
8-19, dorsal vertebrae; 20-
24, lumbar vertebras; A, A,
spinous processes; B, B,
articular facets of trans-
verse processes of first ten
dorsal vertebras; C, auricu-
lar surface of sacrum; D,
D, foramina in transverse
processes of cervical verte-
bras.— (Sappey.)

40 ANATOMY AND PHYSIOLOGY

POINTS OF SPECIAL INTEREST

The cervical vertebrae present a foramen at the base of the
transverse process, the transverse foramen, through which an artery
runs to the brain, entering the skull through the foramen mag-
num. (There are no transverse foramina in the dorsal or lumbar
regions.)

Their spinous processes are cleft or bifid.

Transverse foramen
Transverse process

Articular process

Lamina

Spinous process

Pedicle

FIG. 32. — CERVICAL VERTEBRA, SHOWING BIFID SPINOUS PROCESS. — (Morris.)

FIG. 33. — ATLAS, SUPERIOR SURFACE.
i, Tubercle of anterior arch; 2,
articular facet for odontoid process
of axis; 3, posterior arch and posterior
tubercle; 4, groove for vertebral artery
and first cervical nerve; 5, transverse
process; 6, transverse foramen; 7,
superior articular process; 8, tubercle
for attachment of transverse ligament.
—(Sappey.)

FIG. 34. — Axis POSTERO-
SUPERIOR VIEW.
i, Posterior surface ot
body; 2, odontoid proc-
'ess; 3, 3, superior articu-
lar processes; 4, 4, inferior
articular processes; 5,

5, transverse processes;

6, spinous process.
— (Sappey.)

The first is called the atlas It is a mere ring but has the usual number of
processes (Fig. 33). The atlas is so named because it bears the weight of the
skull (as Atlas, the fabled giant, bore the globe upon his shoulders).

The second is the axis. A strong process projects upward from its body
forming a pivot for the ring-like atlas to revolve around. The pivot is caUed

THE SACRUM 41

the tooth (or odontoid process) and is held in its place in the front part of
the ring of the atlas (Fig. 33) by a strong ligament, which prevents it from
pressing upon the spinal cord.

The thoracic vertebras are peculiar, in that their bodies present
marks for the heads of ribs; also, they have long transverse and
spinous processes.

FIG. 35. — A THORACIC VERTEBRA, SHOWING MARKS FOR HEAD OF 'Rrs. — (Morris.)

The lumbar vertebrae are the largest and strongest in the
column, the bodies being conspicuously thicker than in the other
regions, especially in the case of the fifth.

There are various other modifications of bones in the three regions —
cervical, dorsal, and lumbar — which need not be mentioned here.

FIG. 36. — A LUMBAR VERTEBRA IN SECTION TO SHOW THE PRESSURE CURVES. —

(Morris.)

Sacrum. — An irregular bone formed by the consolidation of
five incomplete vertebrae, and joined to the last lumbar. Its
general shape is that of a curved wedge; it is placed with the
base upward, and the concavity forward, forming the "hollow of
the sacrum." A canal extends from the base to the apex, called
the sacral canal, which is a continuation of the spinal (or neural)
canal.

There are two sets of short canals, running from front to back
through the sacrum. Seen from the front they present, the an-

42 ANATOMY AND PHYSIOLOGY

terior sacral foramina; seen from the back, the posterior sacral
foramina (both are for the passage of nerves). The angle formed
by the sacrum and the fifth lumbar vertebra projects sharply
forward and is called the promontory.

Coccyx. — The terminal bone of the spinal column, and formed
of four very rudimentary vertebrae. The base is joined to the
sacrum; the apex is directed downward and forward.

FIG. 37. — SACRUM, ANTERIOR ASPECT.
i, i, i, i, Bodies of sacral vertebrae with trans-
verse lines of union; 2, 2, 2, 2, anterior sacral foram-
ina; 3, base; 4, auricular surface of lateral aspect;
5, its inferior portion; 6, articular surface of base;
7, notch for formation of last lumbar intervertebral
foramen; 8, superior articular process of first sacral
vertebra; 9, apex of sacrum; 10, cornu; n, notch
for transmission of fifth sacral nerve. — (Sappey.)

FIG. 38. — COCCYX, ANTE-
RIOR ASPECT.
i, Base; 2, 2, cornua; 3,
second coccygeal vertebra;

4, third coccygeal vertebra;

5, fourth coccygeal vertebra;

6, fifth coccygeal vertebra. —
(Sappey.)

THE ARTICULATIONS OF THE SPINAL COLUMN

The bodies of the vertebrae are connected by discs of fibro-
cartilage which are placed between them. They serve not only
to connect the vertebrae but to give flexibility to the column, so
that it may bend in any direction, and they also make it elastic.
The bodies are further connected by fibrous bands on their anterior
and posterior surfaces. (Slightly movable 'or yielding joints.)

The arches are connected by broad thin ligaments between the
laminae, thus completing the spinal or neural canal, which contains
the spinal cord. (These ligaments are an exception to the rule,
in that they are elastic; they are called the ligamenta flava.) The
articular processes are covered with cartilage and enclosed by
capsules which are lined with synovial membrane, forming true
movable joints. These are gliding joints. (Arthrodia.)

The only independent movements of the head are provided for

THE SPINAL COLUMN

43

by the arrangement of the atlas and axis. The cup-like articular
processes of the atlas receive the condyles of the occipital bone to
allow the nodding motion of the head. The occipital bone is held
to the atlas by ligaments, arid rotation of the atlas around the tooth
of the axis turns the head also, from side to side.

The ligamentum nuchae is a name given to a thick elastic band
(not a true ligament) which stretches from
the occipital protuberance to the seventh
spinous process. It helps to sustain the
weight of the head while bending forward,
and is particularly well developed in the
larger grazing animals.

From the seventh cervical down to the sacrum
a supraspinous ligament is stretched, attached to all
the spinous processes.

The movements of the spinal column are
flexion, extension, lateral flexion, and rota-
tion. Motion is freest in the cervical re-
gion, and most restricted in the dorsal. .

Clinical note. — The limited motion be-
tween neighboring bones becomes a wide
range in the column as a whole and may
be increased by frequent and judicious ex-
ercises.

THE SPINE AND THE SPINAL
CURVES

The length of the spine is about 27 inches.
The solid portion is a flexible and elastic
column which bears the weight of the head
and its delicate organs without giving them
the full force of the jar caused by walking,
running, etc. The flexibility of the column
allows the whole body to move with freedom and grace, while the
strength of the spine makes it suitable for the attachment of the
extremities. The arches, connected by their ligaments, enclose
the spinal or neural canal, which extends through the sacrum to

FIG. 39. — SPINE
AND SPINAL CURVES.
— (Sappey.)

44 ANATOMY AND PHYSIOLOGY

the base of the coccyx. . Since the spinal canal contains the spinal
cord there must be places of exit for the spinal nerves; these are
found in the intervertebral foramina between the roots of the
arches.

The spine has/owr curves: cervical, thoracic, lumbar, and sacral.
These are normal curves.

The cervical and lumbar curves are concave posteriorly, as is
seen to a slight degree in the back of the neck, and more plainly
in the so-called "small of the back"; while the thoracic and sacral
curves are concave anteriorly, to accommodate the organs in the
thorax and pelvis.

Th^se curves are caused by variations in the thickness of the bodies and
cartilage discs. So-called "spinal curvature" is an excessive or abnormal
curve. If anterior it is lordosis; if lateral, scoliosis; if posterior, kyphosis.

A lateral curve usually exists in the upper thoracic region, but
this may be called accidental, as it is explained by the excessive
use of one or the other arm.

THE TRUNK

INCLUDES THE -THORAX, ABDOMEN AND PELVIS
BONES OF THE THORAX

Sternum i

Ribs (costae) 24

Thoracic vertebrae 12

Sternum or breast-bone. — Placed in the front of the thorax.
It is about 6 inches long, flat in shape and structure, and its two
surfaces are called anterior and posterior. It has three divisions,
the manubrium, the body, and the xiphoid appendix (Fig. 40).

The upper border of the sternum is notched — the sternal (or
jugular) notch; the lateral borders give attachment from above
downward to the clavicle and the cartilages of the first seven ribs.
The xiphoid appendix is the lowest portion of the bone and gives
attachment to some of the muscles of the abdomen. It remains
cartilaginous until middle life.

Ribs (costa). — Twelve in each side of the thorax, forming a
series of movable elastic arches. They consist of a bony portion
(the costal bone) and a flexible portion (the costal cartilage}. They
are flat in structure, curved in shape.

THE. RIBS 45

The posterior or vertebral extremity is the head, next to the
head is the neck, and the remaining bony portion is the shaft.
The inner surface of the shaft is marked by a groove at its lower
border (the costal groove) in which the intercostal nerves and ves-
sels run, being thus protected from external injury.

FIG. 40. — THE THORAX.

i, 2, Manubrium and body of sternum; 3, xiphoid appendix; 4, circumference of
apex of thorax; 5, circumference of base; 6, first rib; 7, second rib; 8, 8, third, fourth,
fifth, sixth, and seventh ribs; 9, eighth, ninth and tenth ribs, 10, eleventh and twelfth
ribs; n, n, costal cartilages. — (Sappey.)

The first seven are called "true ribs," being connected in front
with the sternum by their cartilages. The remaining five are
"false ribs"; the eighth, ninth and tenth are connected in front, each
to the one above; the eleventh and twelfth are not connected with
anything in front, and are called "floating ribs."

Thoracic vertebrae. — Twelve in number; described with the
bones of the spinal colum'n.

ANATOMY AND PHYSIOLOGY

Tubercle

The seventh rib of the left side, inferior
surface.

The costal groove is seen, to the borders
of which the intercostal muscles are at-
tached, thus completing a channel for in-
tercostal vessels and nerve.

The tubercle is at the beginning of the
shaft; the articular surface marked a is a
part of the tubercle.

FIG. 41. — THE SEVENTH -RIB.
a, articular surface for transverse process; b, neck. — (Morris.)

THE THORAX . 47

ARTICULATIONS OF THE THORAX

•

Sternum. — The three pieces (manubrium, body, and xiphoid
appendix) are connected together by fibro-cartilages and anterior
and posterior ligaments. After middle life they become united in
one bone.

Ribs (costa).* — The costal cartilages are connected in front to
the sternum, or to each other, as already mentioned. The heads
articulate with the bodies of two thoracic vertebrae. (Exceptions:
the first, eleventh, and twelfth are each connected to one body.)
Where the neck of the rib joins the shaft (marked by a tubercle)
it rests against the tip of the transverse process of a vertebra behind

Head of rib

Articular surface of
transverse process

Inter-articular liga-
ment

FIG. 42. — HEADS OF Rms ARTICULATING WITH TWO VERTEBRAE. — (After Morris.)

it, which thus forms a brace for it. All of these joints are enclosed
by capsules and lined with synovial membrane, providing for the
movements of the ribs in breathing, talking, etc. (Figs. 40, 42.)

Vertebrae.- — Their joints have been described.

By the articulation of the ribs with the spine at the back and
the sternum in front, the bony thorax is completed. It is shaped
like a cone, flattened before and behind, and shortest in front
(the sternum reaching only as low as the ninth dorsal vertebra).
The intervals between the ribs are called the intercostal spaces.

The elasticity of the ribs and cartilages and their gliding joints
give a yielding character to the thoracic walls to accommodate the
movements of the lungs within.

48 ANATOMY AND PHYSIOLOGY

BONES OF THE ABDOMEN
The five lumbar vertebrae, already described.
BONES OF THE PELVIC GIRDLE

[ Hip bones 2

The bones are j Sacrum i

1 Coccyx i

Hip-bone (os coxa}.- — Consisting of three parts which are
entirely separate in the child. They are the os ilium, the os ischii,
and the os pubis; they unite to form a cup-shaped cavity called
the acetabulum, seen on the lateral surface of the bone. The
acetabulum is the socket of the hip-joint (Fig. 43).

FIG. 43. — HIP-BONE, EXTERIOR. — (Morris.)

The os ilium is the highest part of the hip-bone and has a broad
expanded portion called the wing (or ala). The medial surface
of the wing is the iliac fossa, which is filled with the iliac muscle;
the lateral surface is crossed by three curved lines (called the pos-
terior gluteal, the anterior gluteal, and the inferior gluteal lines}.

The superior border is called the crest. It can be easily felt,
and the anterior extremity is known as the anterior superior iliac
spine, more often called the spine of the ilium.

The os pubis is the anterior division of the hip-bone. It has

os COX.E 49

a body and two branches,, or rami. The body joins the ilium, the
superior ramus has a short projection called the spine of the pubes,
and the inferior ramus extends downward and backward to join
the ischium, thus forming the upper part of the pubic arch. The
two pubic bones join each other in the median line, forming the
pubic symphysis (symphysis pubis).

Os ilium

Os pubis

Os ischii

Tubcrosity

FIG. 44. — HIP-BONE, INTERIOR, BEFORE UNION OF PARTS. — (Morris.)

The os ischii (or the ischium), the lowest part of the hip-bone,
has a sharp spine projecting backward, a tuberosity upon which
the trunk rests in the sitting position, and a ramus which joins the
pubic ramus to complete the pubic arch.

The ilium, ischium, and pubes united form the hip-bone (os coxae) .
Two large' notches are seen on the posterior border of the completed
bone, separated by the spine of the ischium and called the sciatic
notches. The upper one is the greater and the lower one is the lesser
sciatic notch. In front of the acetabulum is the obturator foramen,
the largest foramen in the skeleton. It is almost entirely closed by
the obturator membrane, which is composed of white fibrous tissue.

THE ARTICULATIONS OF THE PELVIS

The two hip-bones unite with each other in front at the pubic
symphysis, but the sacrum is between them in the back, having

ANATOMY AND PHYSIOLOGY

the coccyx attached to its apex, and thus the pelvic girdle is formed,
usually called the pelvis (or basin). These joints have no cavity,
and are only slightly movable, or yielding. There is a distinct
disc of fibre-cartilage at the pubic symphysis.

Greater sacro-
sciatic ligament

Lesser sacro-sci-
atic ligament

Tendon of biceps muscle

FIG. 45. — GREATER AND LESSER SACRO-SCIATIC LIGAMENTS AND FORAMINA. — (Morris.}

Obstetric note. — The pubic symphysis and the sacro-iliac symphysis
probably soften slightly during pregnancy. The sacro-coccygeal joint has
limited motion until middle life advances, when it may become fixed.

Sacro-sciatic ligaments (Fig. 45). — Two strong bands are stretched
between the sacrum and the ischium. They have no connection with any
joints but are called the greater and the lesser sacro-sciatic ligaments. The
greater (ligamentum sacro-tuberosum) extends from the borders of the sacrum
and coccyx to the tuber osity of the ischium; the lesser (ligamentum sacro-
spinosum) is placed immediately in front of it, extending from the sacrum
and coccyx to the spine of the ischium. Thus are formed two foramina with
the lesser ligament between them, the one above being called the greater
sciatic foramen, and the one below the lesser sciatic foramen. (The sciatic
nerves pass through the greater foramen.)

Poupart's ligament, or the inguinal ligament, may be felt like
a tight cord stretched between the spine of the ilium and the spine
of the pubis — "from spine to spine."

• THE PELVIS 51

The Pelvis or Pelvic Girdle

False pelvis. — The upper part, between the wings of the ilia.
It is broad and shallow.

True pelvis.- — The lower part, bounded by the pubes in front,
the ischia at the sides, and the sacrum and coccyx at the back. It
is deeper and narrower.

The female pelvis has lighter bones, a wider pubic arch, and

FIG. 46. — THE PELVIS. — (Morris.}

greater capacity than the male pelvis; the sacrum is less curved and
the sacral promontory less projecting.

The limiting line or boundary between the false and the true pelvis
is a curved line called the brim, and the space included is the inlet;
the lower opening is the outlet. The inlet and the outlet are also
known as the superior and inferior straits. The measurements or
diameters of these straits in the female pelvis are as follows:

INLET (Edgar's Obstetrics)

Antero-posterior n cm.

(Symphysis to promontory.)
Oblique 12$ cm.

(Ilio-pectineal joint to sacro-iliac joint.)
Transverse 13$ cm.

(Widest part of brim.)

ANATOMY AND PHYSIOLOGY

OUTLET

Antero-posterior 95-12 cm.

(Symphysis to tip of coccyx.)
Transverse 1 1 cm.

(Between tuberosities.)

P. LAC. it S.SAL.

FIG. 47. — THE PELVIS. INLET, OR SUPERIOR STRAIT. — (Sappey.)

i, Iliac fossa; 2, crest of ilium; 3, anterior-superior spine of ilium; 4, anterior-
inferior spine of ilium; 5, ilip-pectineal joint; 6, 7, body and symphysis of pubes;
8, acetabulum; 9, tuber of ischium; 10, u, pubic arch; 12, spines of ischia; 13,
coccyx; 14, sacroiliac joint; 15, is placed just above the promontory.

The nucleus for the ilium appears
early in the second month.

The nucleus for the pubis appears
about the end of the fourth month

The nucleus for the ischium appears
in the third month

FIG. 48. — THE PELVIS OF A FETUS AT BIRTH, TO SHOW THE THREE PORTIONS OF
THE COXAL BONES. — (Morris.)

THE DORSAL AND VENTRAL CAVITIES OF THE BODY

By articulation of the bones of the head and trunk a framework
is formed for two cavities, within which are situated the internal
organs or viscera. (These delicate and important parts must be
provided with surrounding structures which insure both their
safety and efficiency.)

THE VENTRAI, CAVITY 53

The cavities are called dorsal and ventral, or neural and
visceral. Briefly speaking, they may be described as situated
posteriorly and anteriorly to the solid part of the spinal column
or bodies of the vertebrae.

The spinal canal is a part of the dorsal or neural cavity which
extends into the interior of the skull, the bones of the cranium being
modified vertebrae, and the cavity within them representing the
uppermost or cranial part of the neural canal.

The dorsal or neural cavity contains the brain and spinal cord,
well protected within firm, unyielding walls.

The mouth, neck, thorax, abdomen and pelvis inclose the ventral
or visceral cavity, which is in front of the spinal column. The
bony walls are very incomplete, especially in the abdomen. They
are finished out by muscles; this arrangement allows the walls to
be flexible and yielding in character, thus securing to the organs
contained that freedom of movement which is necessary to their
perfect action. The diaphragm (page 97) divides the ventral
cavity into two portions, upper and lower; the pelvic floor (page
no) completes the boundary below.

The ventral cavity contains the organs of respiration, circula-
tion, digestion and reproduction; also the kidneys and bladder,
which are organs of elimination.

Having studied the bones of the dorsal and ventral cavities or
those of the head and trunk, we will proceed in Chapter IV to
those of the extremities.

CHAPTER IV

BONES AND ARTICULATIONS OF THE EXTREMITIES
BONES OF THE UPPER EXTREMITY

The upper extremity, as the artist sees it, begins with the arm.
The anatomist includes the shoulder as a part of the extremity.
The bones are therefore as follows:

j clavicula
I scapula
In the arm. . humerus

In the shoulder.

In the forearm.

In the wrist or carpus

In the hand. .

radius

ulna

scaphoid

semilunar

cuneiform

pisiform

ist row.. .

ad row. . .

trapezium

trapezoid

os magnum j

unciform

palm or metacarpus (metacarpal bones) 5

fingers or digits (phalanges) 14

32

The names of carpal bones are given as follows in Spalteholz's Hand
Atlas:

ist row — os naviculare manus. 2nd row — os multangulum majus.
os lunatum. os multangulum minus,

os triquetrum. os capitatum.

os pisiforme. os hamatum.

Note. — The end of a bone which is nearest to the trunk is called the
proximal extremity; the other end is the distal extremity. The same terms
are applied to surfaces.

THE SHOULDER OR SHOULDER-GIRDLE

Scapula, or shoulder-blade (Fig. 49). — Placed at the upper
part of the chest, behind the ribs (from the second to the eighth).
It is flat and irregular in structure, and triangular in shape.

54

SCAPULA, CLAVICULA

55

The margins are called the superior, the vertebral, and the axillary; the
angles, lateral, medial, and inferior. The inferior angle and vertebral border
or margin usually project a little backward, sometimes very notably, making
the so-called "winged scapula."

The anterior surface (costal surface) is called the subscapular
fossa, and is filled with the subscapular muscle. The posterior or

dorsal surface is crossed by a rough
ridge called the spine of the scapula
which terminates in an important
process, the acromion, overhanging
the shoulder-joint.

Below and in front of the acromion is
the coracoid process.

FIG. 50. — CLAVICLE, INFERIOR ASPECT.

i, Longitudinal depression for insertion
of subclavius muscle; 2, rough impression
for attachment of costoclavicular ligament;
3, 3, for attachment of coraco-clavicular
ligaments; 4, 4, posterior border; 5, s,*an-
terior border; 6, facet for articulation with
sternum; 7, facet for articulation with
acromion. — (Sappey.)

FIG. 49. — SCAPULA, POSTERO-
EXTERNAL ASPECT.

i, Supraspinous fossa; 2, infra-
spinous fossa; 3, superior or coracoid
border; 4, coracoid or suprascapular
notch; 5, axillary or lateral border;

6, anterior angle and glenoid cavity;

7, inferior angle; 8, rough impression
for long head of triceps; 9, medial or
spinal or vertebral hordes; 10, spine;
IT, smooth surface over which tra-
pezius muscle glides; 12, acromion; 13,
base of spine; 14, coracoid process. —
(Sappey.)

The lateral angle presents a shallow depression called the
glenoid cavity. This cavity forms the socket of the shoulder-joint.

Clavicula (or collar-bone, Fig. 50).— Long in shape, but having
no medullary canal. It is curved like an italic letter /and placed
horizontally across the front of the upper ribs. The medial ex-
tremity articulates with the sternum and is therefore called the
sternal extremity. The lateral extremity articulates with the
acromion process of the scapula, and is called the acromial
extremity.

Clinical note. — The weight and curves are increased by exercise,
and both bones are usually more developed in men than in women.

ANATOMY AND PHYSIOLOGY

The clavicula is easily broken, especially in children, being fre-
quently the seat of "green-stick" fracture. (See p. 77.)

The clavicula and scapula together form the
shoulder-girdle, which is open at the back,
but closed in front by the sternum placed be-
tween the two claviculae.

THE ARM OR BRACHIUM

Humerus.' — Long in structure and shape,
having a shaft with a medullary canal and two ex-
tremities.

The upper extremity (proximal extremity)
includes the head, neck and tubercles.

The head articulates with the glenoid cavity
of the scapula to form the shoulder- joint; the
short, thick, anatomic neck joins the head to the
shaft, and just below the neck are the greater and
lesser tubercles for the attachment of muscles to
abduct and rotate the arm. The lower extremity

FIG. 51.— LEFT CUrves slightly forward and presents two pro-
HUMERUS, ANTE- . ••-..,

RIOR ASPECT. jections at the sides called the medial and lateral

i, Shaft or body; epicondyles; the medial is the longer and conse-

2, head; 3, anatomic , . .

neck; 4, greater tu- quently it is more frequently broken oft. Be-
berdej o', ^T",^ tween t^ie epicondyles are the articular surfaces
markings for mus- for the elbow-joint, the trochlea for the ulna and

cles; 10, orifice for , . . . , ..

nutrient artery; n, the capitulum for the radius.

capitulum; 12 tro- The shaft has three borders and three sur-

chlea; 13, 14, lateral

and medial epicon- faces like that of all long bones (on the fibula
anTmedial borders; a fourth border and surface are described).

The Anterior and medial borders run from the greater
and lesser tubercles. In the upper part they are called
the crests of the tubercles and the groove for the long tendon of the biceps
muscle is between them (formerly called bicipital groove as the borders were
called bicipital ridges).

The broad, shallow groove containing the radial nerve winds
across the posterior surface.

Note. — The slender portion of the shaft just below the tubercles
is called the surgical neck, because it is so often fractured.

ULNA, RADIUS

57

FOREARM, OR ANTEBRACHIUM

Ulna. — A long bone in structure and form, situated in the
medial side of the forearm (the ulnar side). The upper extremity
presents two strongly marked processes — the olecranon, pro-
jecting upward from the back and curving
forward, and the coronoid, projecting forward
from, the front and curving upward. Thus
these processes curve toward each other, and
the cavity between them is the semilunar
notch. It receives the trochlea of the humerus
to form the elbow-joint. On the lateral side
of the coronoid process is the radial notch,
where the head of the radius lies.

The lower extremity is the head of the
ulna, which lies in the ulnar notch of the ra-
dius. There is a well-marked projection on
this head called the styloid process.

The posterior border of the shaft is subcutaneous
and may be traced down from the point of the elbow.
The space between the radius and the ulna is called
the interosseous space, and is occupied by an interos-
seous membrane.

Radius. — A long bone in structure and in
form, situated on the lateral side of the forearm
(the radial side).

The upper (or proximal) extremity is the
head, which is depressed at the top to fit the
capitulum of the humerus. Below the head is
the neck, and below that, in front, is the
tuberosity of the radius for the attachment of
the biceps muscle of the arm. The lower (or
distal) extremity of the radius is broad and
thick, and is the largest bone in the formation
of the wrist-joint.

On its lateral aspect is the styloid process. Run-
ning across the upper half of its anterior surface is
the oblique line, which is a part of the anterior border.

Special notes. — The head of the humerus is proximal and articulates with

FIG. 52.— LEFT
ULNA AND RADIUS,
ANTERIOR SUR-
FACES.— (Sappey.)

i, Shaft or body
of ulna; 2, semilunar
notch; 3, radial
notch occupied by
radial head; 4, olec-
ranon; 5, coronoid
process; 6, orifice
for nutrient artery;

7, interosseous bor-
ders with interos-
seous space between;

8, head of ulna; 9,
styloid process of
ulna; 10, shaft or
body of radius; n,
12, head and neck
of radius; 13, tu-
berosity of radius;
14, marking for mus-
cle; 15, 16, lower ex-
tremity and styloid
process.

ANATOMY AND PHYSIOLOGY

the glenoid cavity of the scapula. The head of the radius is proximal and
articulates with the humerus. The head of the ulna is distal.

The upper end of the ulna is its largest part, and an important bone in the
elbow-joint. The lower end of the radius is the largest part, and important in
the wrist-joint. Observe that in the long bones of the upper extremity the
nutrient foramina are in the shafts and are directed toward the elbow-joint.
They transmit nutrient arteries to nourish the bones.

CARPUS

The carpal bones (ossa carpi) are eight in number, and are
typical short bones. They are arranged in two slightly curved
rows — the first and second — with the con-
vexity of the curves turned upward to-
ward the radius, the first row articulating
with it.

FIRST Row

Navicular (os naviculare) . — On the
radial side of the wrist, named from its
shape which resembles a boat, and marked
by a tubercle.

Semilunar (os lunatum). — Well named
from its half-moon shape.

Cuneiform (os triquetrum) . — Very
slightly resembling a wedge.

Pisiform (os pisiforme). — Resembling the half of a split pea,
and placed in front of the cuneiform.

SECOND Row

Trapezium (os multangulum majus). — On the radial side,
marked by a ridge.

Trapezoid (os multangulum minus). — The smallest of the
carpal bones.

Os magnum (os capitatum). — The largest, having head, neck,
and body.

Unciform (os hamatum). — Named for its unciform or hook-
shaped process.

When the carpus is seen from the front, four prominent points
are to be noted, namely — the tubercle of the navicular and ridge

FIG. 53. — BONES OP
CARPUS, DORSAL SURFACE.
— (Sappey.)

BONES OF THE HAND

59

of the trapezium, on the radial side; the pisiform bone and hook
of the unciform on the ulnar side. These mark the boundaries of
a deep groove where the long tendons of the fingers glide.

THE METACARPUS OR PALM

The five metacarpal bones (ossa metacarpalia) are long in
shape but have no medullary canal. Each has a base, a shaft,
and a head, the head being distal. The bases are articulated with
the second row of the carpus, the heads
with the first row of the phalanges. The
first corresponds to the thumb, the second
to the index finger, the third to the middle
finger, the fourth to the ring finger, and
the fifth to the little finger.

The spaces between them are inter-
osseous spaces and are occupied by inter-
osseous muscles.

Note. — The third metacarpal bone '(of
the middle finger) is the longest, and its
head is the most prominent when the hand
is clenched, as in making a "fist."

PHALANGES

FIG. 54. — RIGHT HAND, PAL-
MAR OR VOLAR SURFACE.

mi , , , , , , r- j i-o, Carpus, and grooves

These are the bones of the fingers and for tendons; 10-10, meta-
thumb (digits). A finger has three, first, carP"f; "-". phalanges; xa,

5 C ' J ' 12, 2d phalanges; 13, 13, 3d

second, and third; the thumb has two, first phalanges; 14, 15, istand ad
and second. They are long in shape, but nges of thumb-~

without a medullary canal. Each has a
base, a shaft, and a head, the head being distal. The first row
of phalanges includes those which are next to the metacarpal
bones. The terminal phalanges (those of the third row) have
each a horse-shoe-shaped border on the anterior surface for the
support of the sensitive finger tip; because these bear the nails
they are called the ungual phalanges.1

1 This description of the metacarpal bones and phalanges follows that of standard
text-books. It would seem, however, more in accordance with the facts to con-
sider the palm as composed of four metacarpal bones — one for each finger — and to
give to the thumb three phalanges, since the bone commonly called the first metacarpal
(or the metacarpal of the thumb) resembles those of the first row of the phalanges in
both form and development.

6o

ANATOMY AND PHYSIOLOGY

Resum£. — With the limb in the anatomic position, observe the groove
for the biceps muscles on the front of the humerus, beginning between the
greater and lesser tubercles. In the forearm, note that the ulna is the bone of
the elbow-joint, while the radius makes the wrist-joint; that their shafts are
parallel and the palm is turned forward, and the carpus curved to help in
forming the hollow of the hand (or the "cup of Diogenes"), and that the
thumb is on the radial side, and free.

ARTICULATIONS OF THE UPPER EXTREMITY

Sterno-clavicular, a gliding joint (arthrodia), — This is the one
joint by which the upper extremity articulates with the trunk.

Articular surfaces; on the upper angle of the manubrium and
the sternal end of the davicula. Anterior and posterior ligaments

Inter-articu-
lar ligament

FIG. 55. — STERNO-CLAVICULAR JOINT. — (Morris.)

The inter-articular cartilage is shown in the joint of the right side; capsules shown

on the left side.

connect the bones, forming a capsule. (The joint is divided by a
disc of fibro-cartilage into two cavities and there are two synovial
membranes.}

Motions. — Gliding, by which the shoulder moves upward,
downward, backward and forward.

Ligaments not connected with the joint but useful in preventing dislocation:
— Tbecosto-clavicular, holding the clavicle to the first rib, and the conoid and
trapezoid connecting it with the coracoid process of the scapula. (See Fig. 56.)

Acromio-clavicular. — A small gliding joint between the
acromion process of the scapula and the acromial end of the davicula.
It is enclosed by a capsule.

Shoulder- joint. — A ball-and-socket joint (enar thro sis] . Artie-

SHOULDER- AND ELBOW-JOINTS

6l

ular surfaces: the head of the humerus and the glenoid jossa of the
scapula. The fossa is deepened by a rim of fibro-cartilage called
the glenoid margin. The capsule is attached to the scapula around
the margin of the glenoid fossa, and to the humerus around the
anatomic neck. It is so loose that the head of the humerus will

Superior transverse

scapular ligament

Conoid ligament

Trapezoid ligament

Coraco-acromial ligament

Short bead of bicep=
Subscapular tendon

Capsule of shoulder
Long tendon of biceps

FIG. 56. — ANTERIOR VIEW OF SHOULDER, SHOWING ALSO CORACO-CLAVICULAR AND
CORACO-ACROMIAL LIGAMENTS. — (Morris.)

fall an inch away from the glenoid fossa by its own weight, if the
surrounding muscles be removed; it contains a synovial mem-
brane which covers the glenoid margin and folds like a sheath
around the long tendon of the biceps muscle (Fig. 56).

Motions. — In every possible direction, as flexion, extension, ab-
duction, adduction, rotation, and circumduction, with greater free-
dom than any other joint of the body, because the socket is so
shallow and the capsule is so loose.

Elbow- joint. — A hinge-joint (ginglymus] (Fig. 57).

Articular surfaces: the trochlea of the humerus in the semilunar
notch of the ulna; the capitulum of the humerus in the depressed
head of the radius.

62 ANATOMY AND PHYSIOLOGY

The ligaments — anterior, posterior, medial, and lateral — to-
gether compose a large capsule. (They are attached to the
humerus above the olecranon fossa at the back, and above the coro-
noid and radial fossae in front.) The synomal membrane is
extensive.

Annular ligament
Tendon of biceps

Oblique ligament

Upper edge of inter-
osseous membrane

FIG. 57. — MEDIAL VIEW OP THE ELBOW- JOINT. — (Morris.)

Motions. — The elbow-joint proper is capable of flexion -and
extension only, like all hinge-joints.

The radius and ulna are connected together at their extremities, making
rolling joints (see p. 18); their shafts give attachment to an interosseous
membrane of white fibrous tissue which almost fills the space between the
bones.

Wrist- joint. — Between the forearm and the carpus, having a
variety of gliding motions, but used principally as a hinge-joint.
Articular surfaces: Above — the lower end of the radius and the
triangular cartilage (or articular disc) ; below — the first row of carpal
bones (not including the pisiform) . The ligaments — anterior pos-
terior, medial, and lateral — enclose the joint like a capsule.

Motions. — Flexion, extension, and slight lateral bending (or
from side to side) making abduction and adduction. (If the hand
is bent far backward or over-extended, this is dorsal flexion.)

CARPAL, METACARPAL AND PHALANGEAL JOINTS

Surgical note. — The anterior ligament of the wrist-joint is
remarkably strong and seldom torn; the lower end of the radius
breaks instead, under sudden great force, as in Colics' fracture.

Carpal. — Eight bones arranged in two rows, bound firmly to-
gether by short ligaments. Motions — Gliding only.

Metacarpal. — Five bones, articulated by their bases to the
carpus, and by their heads to the digits. Head of first, belong-
ing to thumb, is free; heads of others connected together by a
transverse band. Motions — Slight gliding, except in case of the

Ulnar radio- ulnar
ligament

Ulnar collateral lig-
ament of wrist
Flexor carpi ulnaris

Radial collateral

ligament of wrist
Volar radio carpal

ligament

Tendon of flexor
carpi radialis

Capsular ligament
of first carpo-met-
acarpal joint

FIG. 58.— ANTERIOR VIEW OF WRIST. — (Morris.)

thumb, which may be flexed or bent upon the palm; extended
or straightened; abducted from hand; adducted toward hand.

Surgical note. — In the normal hand, a dislocation of the thumb
is most difficult of reduction, because the metacarpal head and
the base of the first phalanx are interlocked in such a manner
as to form what is called a joint by reciprocal reception, or "saddle
joint."

Phalangeal. — Three bones in each ringer, two in the thumb.
Anterior, posterior, and lateral ligaments. Motions — Flexion and
extension.

64

ANATOMY AND PHYSIOLOGY

Note. — In the completed hand, the fingers and the thumb can
be moved from side to side, independently; that is, they can be
spread apart (abduction) and drawn together (adduction) (p. 18).

SUPINATION AND PRONATION

These are terms applied to certain movements of the ex-
tremities. They are best seen in the forearm where they change
the position of the hand.

The head of the radius rests in the radial notch of the ulna,
held there by a circular band called the ring ligament (orbicular),
and it can be rolled forward or backward, within the ring (a form
of pivot joint). Of course, the shaft moves at the same time, the
lower end turning forward or backward around the head of the
ulna, and the wrist and hand must accompany it. When the
radius and the ulna are placed in the anatomic position, their
shafts are parallel and the hand lies upon its back ; this is stipula-
tion. If the radius rolls forward, the shafts become crossed, and
the hand lies upon its face; this is pronation.

Surgical notes. — Supination and pronation are very important
movements. If they are prevented the hand loses much of its
usefulness, therefore fractures of the shafts should not be set in
the position of pronation, lest adhesions form between the crossed
shafts, preventing supination.

BONES OF THE LOWER EXTREMITY

In the Thigh Femur i

In the Leg { Tibia

I Fibula

Talus

Calcaneus. .

7

ad row . .

] Cuboid

In the Tarsus j Navicular bone. .

ist cuneiform.. . .

ad cuneiform. . . .

3d cuneiform. . . .

Metatarsus Metatarsal bones 5

Toes or Digits Phalanges 14

Patella . , A sesamoid bone. i

ist row. . .

THE FEMUR

As given by Spalteholtz the names of tarsal bones are: —

Talus |

Calcaneus j

(os calcis)

ist row

Os cuboideum
Os naviculare pedis
Os cuneiforme I
Os cuneiforme II
Os cuneiforme III

THE THIGH

Femur. — The largest bone in the body.

Its upper extremity presents a nearly spherical head joined
by a neck to the shaft, and resting in the acetabulum. At the

FIG. 59. — THE FEMUR, LEFT POS-
TERIOR ASPECT.

1,1, Linea aspera; 2, 2, 3, divisions
of linea aspera; 4, 4, divisions of linea
aspera; 5, 6, head, and mark for liga-
mentum teres; 7, neck; 8, 9, trochanter
major; 10, trochanter minor; n, 12, lat-
eral and medial condyles; 13, intercon-
dyloid notch; 14, 15, lateral and medial
epicondyles. — (Sappey.)

5

FIG. 60. — LEFT TIBIA AND FIBULA,
ANTERIOR ASPECT.

i, Shaft or body of tibia; 2, 3, me-
dial and lateral condyles; 4, spine or
intercondyloid eminence; 5, tubercle of
tibia; 6, crest or shin; 7, 8, lower ex-
tremity, and medial malleolus; 9, shaft
or body of fibula; 10, upper extremity
or head of fibula; n, lower extremity
and lateral malleolus. — (Sappey.)

66 ANATOMY AND PHYSIOLOGY

junction of the neck and shaft are the two trochanters — the
trochanter major on the lateral side, and the Irochanter minor on
the medial and posterior side. The lower extremity presents two
condyles projecting downward, the medial and the lateral. The
medial is slightly longer, the lateral slightly broader of the two;
the deep notch between them is called the intercondyloid notch or
fossa. There is a projection from the side of each condyle called
the medial and the lateral epicondyle.

The shaft has a prominent posterior border called the linea
aspera. This divides lower down into two lines running to the
condyles and enclosing a smooth triangular space called the pop-
liteal space, or plane of the femur. The other borders are not plainly
seen.

THE LEG (FIG. 60)

Tibia. — A long bone in the medial side of the leg. Its upper
extremity is the head, which presents two condyles, medial and
lateral, having shallow depressions on the top to bear the
condyles of the femur. Between these depressions is the inter-
condyloid eminence, or spine of the tibia. The tuberosity of the
tibia is a large elevation in front, just below the head. The lower
extremity has a projection downward from its medial surface called
the medial malleolus, which helps to form the ankle-joint.

The shaft has a prominent anterior border called the crest
or shin, which is plainly felt under the skin. This border and the
medial surface are both called subcutaneous because no muscles
cover them.

Fibula. — A long bone, in the lateral side of the leg, slender and
easily broken. Its upper extremity is the head, which has a short
styloid process pointing upward. The lower extremity is the lateral
malleolus, which helps to form the ankle-joint.

Note. — The space between the tibia and fibula is called the interosseous
space, and is occupied by interosseous membrane.

The lower extremities of these two bones form the prominences
at the side of the ankle known as the ankle-bones; they are the
medial and the lateral malleoli, which, being subcutaneous, are
especially exposed to blows.

Special notes. — Observe that the heads of all three bones are proximal;
that the fibula does not form any part of the knee-joint ; that the nutrient
foramina all run from the knee.

TALUS CALCANEUS

67

THE TARSUS (Fie. 61)

There are seven tarsal. bones arranged in two irregular rows
to form the arches of the foot, or instep.

FIRST Row

Talus (astragalus}. — On the tibial side. Has a head, a neck,
and a body; the body is received between the two malleoli to form
the ankle-joint, and the head is turned forward toward the toes.
It rests upon the calcaneus.

Calcaneus

Talus

Scaphoid, or navicular

First cuneiform

Tarsus

Metatarsus

Phalanges

FIG. 61. — BONES OF LEFT FOOT. — (Morris.}

Calcaneus (os calcis) or bone of the heel.' — The largest tarsal
bone. It is under the talus (astragalus), and bears the weight of
the entire body in the erect position. The tuberosity of the cal-
caneus projects backward beyond the ankle, and gives attachment

68

ANATOMY AND PHYSIOLOGY

to the largest tendon in the body, the tendon of Achilles (tendo
A chillis) .

SECOND Row

Navicular (os naviculare) . — On the tibial side, in front of the
talus, articulating with its head

Cuneiform bones (or wedge-shaped bones) . — In front of the
navicular. They are three in number, first, second, and third.

Cuboid (os cuboideum). — It lies in front of the calcaneus.

THE METATARSUS

The five metatarsal bones in the foot resemble the metacarpal
bones of the hand in the general characteristics, with some special
developments; the inter osseous spaces between them are occupied
by interosseous muscles.

PHALANGES

Fourteen in number, as in the hand, and arranged in a similar
manner — two for the great toe, and three for each of the other
toes.

A. B.

FIG. 62. LEFT PATELLA. FIG. 63.

A, ANTERIOR SURFACE; B, POSTERIOR SURFACE. — (Morris.)

Note.- — The great toe is in the medial border of the foot.

PATELLA

The patella is the largest sesamoid bone. It is triangular in
shape, placed in front of the knee-joint, and held to the tuber-
osity of the tibia by a strong band about three inches long — the

HIP-JOINT

69

Tendon of biceps
muscle

. Capsule

FIG. 64. — HIP-JOINT. — (Morris.)

psuie
Glenoid rim

Ca psule

FIG. 65. — LIGAMENTUM TERES. — (Morris.)

70 ANATOMY AND PHYSIOLOGY

so-called ligament of the patella. Its location while the body is
erect is in front of the condyles of the femur, but in the sitting
position it is in front of the lower ends of the condyles, and in
kneeling it is beneath them.

ARTICULATIONS OF THE LOWER EXTREMITY

Hip- joint (ball-and-socket joint) (Enarthrosis) . Articular sur-
faces: head of the femur, and the acetabulum deepened by the
glenoid rim of the acetabulum (a rim of nbro-cartilage) . The
bones are directly connected by the ligamentum teres (or round
ligament) within the joint, which is attached by one extremity near
the middle of the head, and by the other to the bottom of the
acetabulum (Fig. 65).

A capsule encloses the joint. It is strengthened by special
bands of fibers extending to surrounding bones — one, the ilio-
femoral from the ilium to the great trochanter, resembles an in-
verted letter Y, and was formerly called the Y-ligament (also the
ligament of Bigelow) . The synovial membrane not only lines the
capsule but invests the ligamentum teres.

Motions. — Free motion in every direction, like that of the
shoulder.

Knee-joint (hinge or ginglymus joint) (Fig. 66). — Articular
surfaces: the condyles of the femur, the head of the tibia, and the
posterior surface of the patella. The two surfaces on the top of
the tibia are shallow, but their depth is increased by semilunar
fibro-cartilages attached around the borders, thus forming shallow
cups for the condyles.

The femur and tibia are directly connected by two ligaments
within the joint, which cross each other and are therefore called
the crucial ligaments. (One passes from the' front of the spine to
the lateral condyle, the other passes from behind the spine to the
medial condyle.) The patella lies in front of the condyles, being
imbedded in a thick tendinous band about three inches long which
continues to the tuberosity of the tibia. (This band is really the
tendon of insertion for some thigh muscles, and is improperly
called the ligament of the patella.} It serves as the anterior liga-
ment of the joint but is at the same time the quadriceps extensor
tendon, sometimes called the patellar tendon. There are distinct

KNEE-JOINT 71

medial and lateral ligaments, and some strong oblique bands at the
back; and all are connected by a capsule which encloses the joint
cavity.

The synovial membrane is very extensive (Fig. 66) ; it covers
the crucial ligaments and semilunar cartilages.

Motions. — Flexion, extension, and very limited rotation of the
leg.

Note. — The patella cannot be drawn upward under any circumstances.
When the knee is flexed it lies against the lower ends of the condyles, and in
kneeling the condyles rest upon it. The elasticity of the great muscles to

Extension of synovial sac of kn
upon femur

Tendon of quadriceps extensor,
forming fibrous capsule of joint

Patella

Pre-patellar bursa
Condyle of femur (innei
Ligamentum mucosum

Fatty tissue

ynovial membrane re-
flected off crucial liga-
ments

;ut end of anterior cru-
cial ligament
Posterior crucial liga-
ment

Fatty tissue between
ligamentum patellae
and synovial sac

Bursa beneath ligamentum
patellae

Tibia

FIG. 66. — INTERIOR OF KNEE-JOINT. — (Morris.)

which the pateDar tendon belongs, allows very free motion and at the same
time keeps the patella always in place close to the condyles.

Burse. — There are several small cavities called bursae, the use of which is
to prevent friction in the tissue outside the knee-joint. They usually com-
municate with the joint. The largest one is, however, subcutaneous, being
in front of the patella between it and the skin. (Fig. 66 and page 82.)

72 ANATOMY AND PHYSIOLOGY

Surgical note. — This prepatellar bursa is subject to frequent
pressure and easily becomes inflamed and enlarged, making the
so-called "housemaid's knee."

Ankle-joint (Hinge- joint). — Articular surfaces on the medial
and lateral malleoli and the body of the talus. They are connected
by anterior, posterior, and lateral ligaments.

The medial is often called the deltoid ligament, from its shape A like the
Greek letter delta, and the lateral ligament is in three distinct bands, the
anterior, middle, and posterior.

Motions. — Flexion, extension, and slight abduction and adduc-

Plantar ligaments

FIG. 67. — LIGAMENTS OF THE ANKLE-JOINT AND PLANTAR REGION. — (Morris.)

tion; also lifting the medial border, or eversion, and lifting the
lateral border, or inversion.

Notes. — The transverse ligament is a special band behind the talus, connect-
ing the two malleoli, to prevent backward dislocation of the foot in jumping,
running, etc.

There is no motion of the lower extremity which corresponds to supination
in the upper, the whole extremity being in the permanently pronated position,
which brings the great toe toward the median line of the body, or on the
medial border of the foot. (The thumb is on the lateral border of the hand.)

Tarsal joints. — An inter osseous ligament connects the talus to the
calcaneus; it is the strongest one in the body. Short fibrous bands

ARCHES OF THE FOOT

73

connect the various tarsal bones to each other to complete the
instep, and there is one elastic ligament upon which the head of the
talus rests. It assists to prevent excessive jarring as the foot
strikes the ground. (This is the only ligament containing elastic
tissue in the extremities.)

Metatarsal. — Like the metacarpal, except that the heads are
all joined together by a transverse band; the great toe is not free.

Phalangeal. — Like those of the hand.

Arches of the foot. — The principal arch is from the heel to
the ball of the foot; a second one, the transverse, is equally im-

Tendo Achillia
Talus Vessels and nerve

Scaphoid
First cuneiform

First metatarsal

Calcaneus

Muscles of plantar region

PIG. 68. — MEDIAL BORDER OF RIGHT FOOT, SHOWING BONES IN POSITION. — (Morris.)

portant. The arteries and nerves in the sole of the foot are pro-
tected from pressure by these arches, which are preserved not
only by the ligaments and the shape of the bones, but by the
tendons of certain muscles.

Practical points. — In walking the weight is transmitted principally through
the talus, the navicular, and three cuneiform bones to the three medial toes,
giving the "springy" step to the well-arched foot. In standing, it falls more
upon the calcaneus, and is distributed through the cuboid to the two lateral
toes as well.

RESUME

Comparing the joints in the upper and lower extremities, note
that both the shoulder and hip are ball-and-socket joints; that

74 ANATOMY AND PHYSIOLOGY .

the elbow and knee are hinge-joints, as are also the wrist and
ankle; but whereas in the wrist extension is limited, in the ankle
it is so free as to bend the top of the foot almost against the leg,
becoming dorsal flexion, and is actually called flexion of the ankle-
joint, the term extension being used to signify the act of straighten-
ing the foot in a line with the leg.

The back of the hand and the top of the foot are both called
the dorsum; the face of the hand is the palm or volar surface, and
the sole of the foot is the plantar surface. The thumb is free; the
great toe is bound with the others.

The following table of articular nerves is inserted in this place
for convenient reference, when, in the care of painful Joint affec-
tions, the nurse may be interested to know the names of the par-
ticular nerves involved.

NERVE SUPPLY TO THE PRINCIPAL JOINTS

Temporo-mandibular. . . Fifth cranial or trifacial.

Shoulder Suprascapular, subscapular, axillary.

Elbow Musculo-cutaneous (principally).

Wrist and hand , . Ulnar, median, deep branch of radial.

Joints of spinal column. Spinal nerves.

Hip Femoral, obturators, sciatic.

Knee Femoral, obturator, tibial, peroneal.

Ankle and foot Deep branch of peroneal, two plantar nerves.

CHAPTER V
COMPLETION, REPAIR AND FUNCTIONS OF BONES

NOTES CONCERNING THE COMPLETION OF LONG BONES

In the humerus, radius, and ulna, the nutrient canals lead toward the elbow
and the bones are completed here at an earlier date than at the wrist or
shoulder. In the femur, tibia, and fibula, the nutrient canals lead away
from the knee; and the bones are completed first at the hip and the ankle.

Surgical notes. — The time of union of -the extremities and shafts of long
bones is important from a surgical viewpoint. Thus, in the ends of bones
at the elbow-joint the extremities join the shafts at about the seventeenth or
eighteenth year; therefore, injuries near the elbow-joint before this age may
cause a separation of the parts, called an epiphyseal fracture. The upper
end of the humerus and lower ends of the radius and ulna unite with their
shafts at about the twentieth year; therefore, in the case of an injury of the
shoulder or wrist before this age the same possibility is borne in mind.

In the lower extremity certain differences are noted, since the nutrient
arteries run differently. The bones are completed first at the upper end of the
thigh, at about nineteen, and at the lower end of the leg at about eighteen or
twenty years, while the knee is completed last, at between twenty and
twenty-five.

It is important for the nurse to understand something of the
nature of the baby's skeleton. The general condition at certain
periods of life is also of interest.

BRIEF SURVEY OF THE SKELETON AT DIFFERENT AGES

At birth:—

Head Skull-bones have unossified borders and angles, there-
fore, the membrane is soft at the fontanelles; the base
of the skull is largely in cartilage, and the bones are
slightly movable.

Face-bones small and very incomplete.

Spinal column Bodies of vertebrae partially ossified, with much carti-
lage between them.
Arches, each in two separate pieces or halves.

Pelvic-girdle Hip-bones (ossa coxae) in three pieces, well separated

by cartilage.

Sacrum partially ossified.
Coccyx not at all ossified.
Ribs Shafts only are bony.

75

76 ANATOMY AND PHYSIOLOGY

Sternum Presents a number of small centers, imbedded in cartil-

lage.

Upper extremity Shoulder-girdle ossified at acromial end of clavicula and

in body of scapula; other parts are cartilage.
Long bones — Shafts partially ossified.
Carpus — :all bones entirely cartilaginous.

Lower extremity . . . Long bones — Shafts partially ossified; at the knee the

ends of the femur and the tibia have begun to ossify.

Tarsus — three bones (talus, calcaneus, and cuboideum)

have begun to ossify.
The metacarpal, metatarsal and phalangeal bones have

thin lines of osseous tissue before birth.
At age of 20 years
Head

Hands

All completed.

Feet

Long bones All completed except tibia and fibula whose upper ends

are not yet united with the shafts.
Ribs

, Are in two pieces each.

Sternum J

Shoulder-girdle Clavicula, sternal end still separate. Scapula soft at

borders and processes.
Pelvic-girdle Hip-bones (ossa coxae) completed. Sacrum and coccyx

still in two or more pieces.

Spinal column All parts ossified.

At age of 25 years : . The skeleton is practically completed. The bones are

strong, and the 'proper proportions of animal and

mineral matter are preserved during adult life.
The coccyx may unite with the sacrum in middle life,

thus modifying one of the diameters of the pelvic

outlet.
In old age : There is no more growth. The supply of animal

matter decreases, and the bones become brittle so

that they may be easily broken.

POINTS OF PRACTICAL INTEREST CONCERNING THE BONES IN

INFANCY

First, the baby's bones are soft, and are still largely composed
of cartilage. Second, since the process of ossification is going on
continually, the proper shape of the cartilage should be preserved
in order that the shape of the future bone may be normal. In
infancy the skull bones are movable as well as soft, and the shape of
the baby's head may be altered by pressure. Witness the Flathead
Indians, who bind a board across the top of the infant's skull.

REPAIR OF BONE 77

The spine and the vertebral extremities of the ribs are com-
posed largely of cartilage; it is therefore evident that not only
should a young baby's back be supported, but the child should
rest in a horizontal position, the spine being so soft that it cannot
easily be held upright, even if the little muscles were strong
enough to do this without fatigue.

The pelvis and hip. — During the first year or two both the
sacrum and the coccyx are still in separate pieces, while the centers
in the three portions of the hip-bones are well separated by cartil-
age, leaving the acetabulum unossified; the head of the femur is also
soft. Consequently, a thought only is needed to explain why the
clothing about a, baby's hips should leave them free from pressure.

Note.' — An advantage is derived from the softness of the
skeleton during childhood, as the many jarrings and tumbles
incident to the child's experience are far less injurious to the jelly-
like frame than they would be to a harder one.

Green-stick fracture.- — Up to the age of four years the bones
are sufficiently soft to bend rather than break, as an older bone
would do under similar circumstances. Usually some of the
fibers do break, but not the whole bone; this is called a green-
stick fracture, because the bone behaves like a bough of green
wood when forcibly bent.

Rachitis or rickets. — In this disease ossification is delayed,
and the bones are more soft and yielding than usual until com-
pletely ossified. The extremities grow larger and the shafts are
often bent. When the mineral salts are finally deposited the bone
is permanently misshapen. Rachitis is a disease of malnutrition
from deficiency of mineral food.

Spina bifida. — In the formation of the vertebrae, the comple-
tion of the arches and spinous processes occurs latest in the lower
lumbar and upper sacral region. Sometimes it is not perfect, and
the spinal canal is then left open. This condition is known as
spina bifida and the membranes and fluid of the spinal cord pro-
trude, forming a tumor upon the child's back. Spina bifida
occurs rarely in other regions.

REPAIR OF BONE

When a bone is broken nature repairs it in her own way.
First, more blood flows to the part; then a certain amount of

7 8 ANATOMY AND PHYSIOLOGY

animal matter like cartilage, appears about the fracture, forming
a callus. This is soon hardened by deposit of mineral matter and
the callus becomes bone, but the mark of fracture and repair will
always remain. The callus will form and unite the ends of bone
even if they are not well matched, but in this case deformity will
result. If the callus does not harden the union is fibrous.

Surgical note. — " Setting" a fractured bone consists in .placing
the ends in proper position, or "apposition." This, nature can-
not do, because the muscles above and below are pulling them
out of place, therefore the skill of the surgeon is required for its
accomplishment.

Practical point. — The nursing care of a fracture is directed to
the end of keeping the bone supported in position, and as far as
may be, perfectly quiet until the callus is hardened, so that the
least possible deformity will remain. To accomplish this the
nurse must not only have a knowledge of anatomy, but must
exercise skill and judgment to an unusual degree.

PHYSIOLOGY OF BONE AND THE SKELETON

At first thought it .would appear that not much could be said
concerning the physiology of bone tissue, which is a finished prod-
uct, the changes which it undergoes being directed solely to its
own preservation. The ability of bone to repair injuries by utiliz-
ing material from the blood is, however, a physiologic process;
and the membranes which cover bony surfaces (periosteum
outside, endosteum within medullary canals) have a well-defined
function in the formation of bone tissues-, already referred to.
One of the most important functions of the body, namely: — pro-
viding an origin for cells (or corpuscles) of the blood, belongs to the
marrow of bones. Cancellous bone contains in its spaces thin red
marrow (the "red bone marrow" of clinic use) in which red cells
have their origin, while the medullary canals of long bones contain
a firmer fatty marrow where many of the white cells of the blood
have their beginning.

Taking a broad view, we find many points of interest in the
bones and the skeleton which they comprise, some of which have
already been touched upon. It is their mechanical physiology
which is conspicuous and of great importance — they afford attach-
ment to muscles; they enclose cavities; they sustain pressure.

THE ARTICULATED SKELETON 79

Their usefulness is due to their physical characteristics — for in-
stance, the hardness of bones enables the framework which they com-
pose to support the soft parts of the body, and in certain localities
enables them to protect internal organs. An important example
is the neural canal with its contents' — the brain and spinal cord.

Again, it is this same quality of hardness which enables the skel-
eton to bear direct pressure and the body weight. Osseous tissue
in certain bones — notably the femur and the os coxae — is especially
arranged in lines of pressure for this purpose; namely, that super-
imposed weight may be borne with the least strain upon the bone.

The relation between the shapes of bones and the arrangement
of their two tissues has a direct bearing upon their usefulness and
the convenience with which it is exercised. Examples are seen
in the long bones — their (comparatively) large extremities enter
into the formation of joints; they also give attachment to many
muscles which move the joints. Here, extent of surface is needed
and cancellous bone is used with but a thin covering of compact,
thus securing the necessary surface without undue weight. Their
shafts give attachment to fewer muscles, but their position in the
extremity exposes them to violence (applied transversely) and
calls for endurance of strain. Hence, for these two reasons — first,
that extent of surface is unnecessary; and second, that strength
and endurance are demanded' — the compact tissue is appropriate.
It also secures a convenient slenderness of bone where the bulk of
muscle tissue is greatest.

By far the greatest variety of functions is seen in the articu-
lated skeleton, whereby the movements necessary to the well-being
of the individual are made possible by the character of the joints.

The movements of the trunk are Iimited5 but sufficient for the
needs of the organs which it contains; while those of the extremities
are many and free. They may resist external force; they may
themselves overcome opposing forces. They may be used as
weapons of offense or defense. Facilities for transporting the body
from place to place, or locomotion, are provided by the articulated
bones of the lower extremities; and the power of the upper ex-
tremities to perform a thousand necessary acts would not exist
without a similar framework. These points have been mentioned
already, and will be dwelt upon later in connection with the study
of the muscular system.

CHAPTER VI

THE CONNECTIVE TISSUE FRAMEWORK AND THE
SKELETAL MUSCLE SYSTEM

THE FASCIAE OF THE BODY AND MUSCLES OF THE
HEAD AND TRUNK

Although present in every part of the body, the connective
tissue is so conspicuously associated with the muscle system that
a few facts of interest concerning this universal tissue are here
reviewed, before commencing the study of the muscles.

For muscles it is a veritable framework, as will be seen. In
fibrous form it is conspicuous on their surfaces as sheaths, or as
separating one from another; and in tendons. As delicate areolar
tissue it invades them, bearing tiny vessels and nerves and forming
tissue-spaces.

This it does in all organs — wrapping them, supporting their
cells, and invading them to convey vessels and nerves. It fills in
spaces between organs, and accompanies large vessels to and from
them. It connects organs to each other; and everywhere it forms
a network of tissue-spaces containing nutritive fluid obtained from
the blood-vessels for the cells of the body. .

If one could imagine that everything in the human body ex-
cept connective tissue could be destroyed, the remaining portion
would bear the same relation to the body that had been, as a
skeleton leaf bears to a fresh green one.

THE FASCIAE OF THE BODY

The word fascia is applied to the connective tissue which
surrounds various organs or lines cavities. Fascia is found in
every part of the body, and we shall study here two varieties, which
are associated with the muscles and skin. They are called the
deep and the superficial fascia.

The deep fascia. — This is a firm layer of connective tissue
with but small spaces between its fibers, therefore it is dense and

DEEP FASCIA

8l

tough. It is white and smooth, and
seldom contains any fat. The deep
fascia covers ^he muscles and binds
them down, and also separates them
into groups, thus forming inter mus-
cular sepia. (Many muscle fibers
arise from intermuscular septa.)

Special points. — The inguinal
ligament (Fig. 79) is a band of the
deep fascia between the spine of the
ilium and the tubercle of the pubes.
It feels like a cord from one bone to
the other.

The fascia lata (broad fascia) is that

FIG. 69. — DEEP FASCIA OF THIGH FIG. 7.0. — SHOWING OVAL FOSSA.
(Partial). 6, 7, 8, 10, 14, indicate por- The superficial fascia has been dissected
tions of fascia lata. — (Sappey.) away, leaving cutaneous veins lying

upon deep fascia.

portion of the deep fascia which covers the muscles of the thigh; it is thicker
and stronger than any other fascia of the body. It is attached to the hip-
bones above and the leg-bones below. A portion which is especially tense
6

82 ANATOMY AND PHYSIOLOGY

and strong may be felt on the lateral side of the thigh, above the tuberosity
of the femur, like a tight band attached to the tibia; it is called the ilio-tibial
gland. See page 113, tensor fasciae latce.

The oval fossa or saphenous opening (Fig 70) in the fascia
lata is an inch and a half below the medial portion of the inguinal
ligament. It allows the long saphena vein to pass through to the
femoral vein.

The lumbar fascia is not a part of the general deep fascia of the body,
but belongs to the transversus muscle described on p. 96. It is attached
behind to the lumbar vertebra, above to the last two ribs, and below to the
crest of the ilium.

The superficial fascia covers the deep fascia. It lies immedi-
ately beneath the skin in its whole extent and consists of loose-
meshed connective tissue, arranged somewhat hi layers, and con-
taining the subcutaneous fat. It also imbeds the superficial or
cutaneous arteries, veins, and nerves between its layers. In
places where the fascia is thin, as on the back of the hand, the
veins are easily seen. This fascia is closely connected with the
skin, and they glide together over the deeper structures.

A bursa is a sac in the fascia which contains smooth fluid
resembling synovia. Bursa are found where much pressure or
friction occurs between different structures. They act like
water-cushions, thus saving the tissues from bruising or rubbing.
The largest subcutaneous bursa is in the superficial fascia in front
of the patella. It is called the prepatellar bursa (Fig. 66).

Surgical note. — When the prepatellar bursa becomes in-
flamed and enlarged, it forms "housemaid's knee."

Sometimes bursae are placed underneath tendons or between
muscles, and these deep ones may communicate with joints.
There is a large one between the gluteus maximus and the tuber-
osity of the ischium, and another between the same muscle and
the great trochanter.

Note. — The transversalis and pelvic fasciae are found within the abdomen
and the pelvis, respectively (seepages 100 and in).

MUSCLES, THEIR IMPORTANCE

The growth of bone and fashioning of joints has but prepared
the way for more important ends to be accomplished.

The head and trunk protect and support the vital organs, but

MUSCLE STRUCTURE 83

the food and the air upon which their life depends come only
through the aid of those constant workers, the muscles. All
motion of any sort in the body, whether conscious or unconscious,
is due to their action. If the motion is voluntary it is due to
muscles which are controlled by the will, or voluntary muscles.
Muscles which cannot be controlled by the will are involuntary;
they are found in the internal organs of the body, or the viscera,
and in the coats of vessels. All other muscles are voluntary, and
since they are attached to bones they are called skeletal muscles.

Contractile tissues: — Muscular and ciliated epithelial cells.
Striped skeletal muscle.
Striped cardiac muscle.
Unstriped visceral muscle.

STRUCTURE OF MUSCLES

Muscles consist chiefly of collections of red fibers, each fiber
composed of little bundles of muscle-cells. All of these are
wrapped in connective tissue, bound together and enclosed in a
sheath.

Transition zone.

Nucleus tendon. 0 Z

FIG. 71. — LONGITUDINAL SECTION OF A PART OF A MUSCLE FIBERVFROM A
HUMAN INTERNAL INTERCOSTAL MUSCLE, SHOWING ITS TRANSITION TO TENDON.
X 750. — (Lewis and St'dhr.)

Examining a muscle with care, we can strip off the sheath of connective
tissue (epi-mysium) , and we shall find that it sends layers down into the
muscle to form septa or partitions (peri-mysium) enclosing the bundles (or
fasciculi) of which the muscle is made up.

With the aid of the microscope the fiber cells which compose the bundles
are revealed, surrounded by still more delicate connective tissue (endo-
mysium).

Also, under the microscope the fiber cells of voluntary muscle tissue ap-
pear striped, consequently voluntary muscle is said to be striped or striated.
Involuntary fiber cells are plain — involuntary muscle is unstriped or non-
striated. This sort of muscle is found in internal organs, whose work must go
on continually without our conscious supervision.

84

ANATOMY AND PHYSIOLOGY

Exception. — The heart: which acts whether we will or not, although its
muscle is striated.

In most cases the connective tissue is prolonged beyond the
muscle into a white cord or band called a tendon, if the muscle is
long and thick; or into a broad thin layer called an aponeurosis if
the muscle is flat; and by these tendons and aponeuroses the

FIG. 72. — SHOWING EXTREMITIES OF
MUSCLES. 2, Tendqn. 5, Aponeuro-
sis.— (Sappey.)

FIG. 73. — INTERCOSTAL MUSCLES. —
(Morris.}

muscles are attached to bones and other organs. Sometimes the
red fibers are attached directly to the parts which they move, but
in by far the greater number the tendons are conspicuous (Fg. 72).
Muscles are described as consisting of a body and two ex-
tremities; the body or belly being the red contracting part which
swells in action, while tendons (which are possessed by most of the

INTERCOSTAL MUSCLES - 8$

muscles) are simply strong white fibrous bands having no power to
contract and no elasticity. This is equally true of the aponeuroses.

The attachments of the extremities are spoken of as the origin
and the insertion. The extremity which is stationary while the
other end moves, is the origin; the end which moves with the
organ attached to it, is the insertion.
The insertion is always pulled toward the
origin when the muscle contracts.

The names of muscles are not applied
according to a uniform plan, being some-
times chosen because of location, as the
intercostals (between ribs) or the epicranial
muscle (upon the head), etc; or, the shape
may determine the name, as orbicularis
oris (ring muscle of the mouth) ; but of tenest
the name signifies the action of the muscle.
The original names are in the Latin tongue
but the English translation is often used.
The full Latin name includes the word
musculus (muscle) which is quite com-
monly omitted for the sake of brevity.

SKELETAL MUSCLES OF THE TRUNK*

Intercostal muscles. — In two sets, the
internal and the external, which occupy
the intercostal spaces. The fibers run

obliquely from rib to rib, the internal

., • j j f j 4.1. FlG- 74-— THE FIGURES

fibers running upward and forward, the REFER TO THE SPINAL GROUP

rnnnno- mtYMiunvr sitt/ AND THE QuADRATUS LuM-

nnmg downward and BORUM._(>oWerV Anatomy.)
forward. (Fig. 73.)

Action. — They move the ribs up and down in breathing and
the various acts associated with it.

PRINCIPAL MUSCLES OF THE BACK

In the skeleton a broad groove exists on either side of the
spinous processes, which is filled in its whole extent with many
vertical muscles of different lengths, the use of which is to hold

1 Many skeletal muscles have their origin partly from the deep fascia covering
them. The bony origins alone are given here, as a rule and only the more important
of those.

86 ANATOMY AND PHYSIOLOGY

the spine in the erect position; also they assist to move it in
various directions.

The erector spinae is the name given to this large group,
which is bound down in its place by a thin layer of fibrous tissue
called the vertebral aponeurosis. This muscle group extends from
the skull to the lower part of the sacrum (Fig. 74).

The action is most easily seen in the lumbar and dorsal regions,
where it is not deeply covered with other muscles.

Nerves. — Posterior spinal.

The latissimus dorsi (broadest of the back, Fig. 75). — This
muscle covers most of the erector spinae and a great portion of
the back of the trunk.

Origin. — The spinous processes, from the sixth thoracic down
to the end of the column. (Also the crest of the ilium and a few
fibers from the inferior angle of the scapula.) Insertion. — The
crest of the lesser tubercle of the humerus.

Action. — Principally to pull the arm backward and keep the
scapula or shoulder-blade close to the chest; brought prominently
into use in rowing a boat or when the body is suspended by the
hands and an effort is made to draw it up.

Nerves. — Posterior spinal and long subscapular. .

MUSCLES OF THE BACK OF THE NECK

These muscles move the head and neck. Only the most
important are here described.

The splenius. — This muscle is in two portions, the splenius of the head
(capitis) and the splenius of the neck (cervicis).

Origin. — The spinous processes of the last cervical and first six thoracic
vertebrae. Insertion. — Partly upon occipital and mastoid bones (splenius
capitis) and partly upon the transverse processes of the upper vertebrae
(splenitis cervicis).

Action. — The muscle of one side alone will rotate the head, twisting the
neck. The muscles of both sides acting together simply pull the head back-
ward or extend it and the neck.

Nerves. — Posterior cervical.

The trapezius covers the other muscles of the back of the
neck, and also the upper portion of the latissimus dorsi. It is one
of the largest muscles in the body (Fig. 75). The two muscles,
right and left together, make a large diamond-shaped sheet.

TRAPEZIUS 87

Origin. — The occipital bone, the ligamentum nuchae, and the
spinous processes of the thoracic vertebrae. Insertion. — The spine
of the scapula and lateral third of the clavicula.

Action. — With the shoulders stationary the trapezius acts upon
the head to pull it backward or sideways. With the head station-

FIG. 75. — SUPERFICIAL AND MIDDLE MUSCULAR LAYERS OP THE POSTERIOR ASPECT

OF THE TRUNK. — (Sappey.)

i, Trapezius; 2, latissimus dorsi; 3, aponeurosis; 4, 5, 6, 8, 19, 20, different por-
tions of latissimus dorsi; 0-12, deep muscles; 13, sterno-mastoid; 14, splenius; 15,
elevator of scapula; 16, infraspinatus; 17, teres minor; 7, 18, teres major; 21, portion
of anterior serratus; 22, 23, abdominal muscles; 24, 25, gluteus maximus; 26-30,
deep muscles; 31, deltoid; 32, triceps.

ary it can elevate the shoulder-girdle and the whole upper ex-
tremity with it. Both muscles together can draw the shoulders

88

ANATOMY AND PHYSIOLOGY

back. If the hands grasp a bar above the head these muscles
will assist to draw the body up. The largest two of the " climbing
muscles" are the latissimus dorsi and the trapezius.
Nerves. — Spinal accessory and middle cervical.

Note. — Observe in the illustration its tendinous area, which remains flat
during action of the muscle.

Frontails

Ear muscles

Sterno-mastoid

FIG. 76. — MUSCLES OF THE HEAD AXD NECK. — (Morris.)

Clinical Note. — Spasmodic action of the trapezius is often the
cause of wry-neck, or torticollis, and this may be increased by
spasm of the splenius.

MUSCLES OF EXPRESSION 89

MUSCLES OF HEAD, AND FRONT AND SIDE OF THE NECK.

The muscles of expression are those of the scalp and face.
They are closely connected with the under surface of the skin, or
with each other; they have no deep fascia over them, and there-
fore their slightest contraction is shown on the face, thus varying
the movements and lines, of expression.

Epicranial muscle. — On the forehead and the top and back
of the head — a broad thin muscle made up of two distinct parts
with an aponeurosis between them. The posterior part is the
occipitalis, taking origin from the curved line of the occipital
bone and ending in the aponeurosis on the top of the head. The
anterior part is the frontalis, having origin in the aponeurosis,
and passing down over the forehead to the insertion in the tissues
of the eyebrows.

Action. — Principally to lift the eyebrows, producing the trans-
verse wrinkles across the forehead which express surprise. The
skin is closely connected with this double muscle so that the
contraction causes movement of the scalp. (Some people can
move the scalp backward and forward by contracting the two
portions alternately.)

The aponeurosis extends in a thin layer at the side over the temporal
region, giving origin to certain small muscles which move the ear. The scalp
and ear usually move together.

Nerve. — Seventh cranial (or facial).

Levator palpebrae (elevator of the eyelid). — Within the orbit.
Origin. — At the apex of the orbit. Insertion. — In the upper lid.
Action. — It lifts the lid and opens the eye.

Nerve. — Seventh cranial. See page 343 for other Orbital Muscles.

Corrugator. — The muscle which wrinkles the eyebrow.
Origin. — The frontal bone. Insertion. — The under surface of
eyebrow.

Action. — It draws the brows downward and inward toward
each other; it is the frowning muscle.

Nerve. — Seventh cranial.

Orbicularis oculi. — The ring-like muscle of the eyelid. It is
attached to the medial border of the orbit. Some of its fibers
are in the lid — the palpebral portion — while others surround the

90 ANATOMY AND PHYSIOLOGY

lids like a broad flat ribbon, forming the circular or orbital portion,
and bearing the eyebrows (Fig. 76).

Action. — When the palpebral fibers contract the lids cover the
eyeballs lightly; when the circular fibers contract the lids are
pressed against the ball.

Nerve. — Seventh cranial.

Orbicularis oris (ring muscle of the mouth). — Surrounds the
opening of the mouth, constituting the larger portion of the lips.
The fibers have only one bony attachment — on the maxilla, below
the septum of the nose.

Action. — It closes the mouth.

The lips themselves are moved in various ways by muscles
above and below them — the elevators and depressors of the lips
(all supplied by the seventh cranial nerve}.

Special points. — Most of the changes in the expression of the face are
caused by the action of the ring muscles and of those which are attached to
them. For example, the lifting of the eyelids by the frontalis expresses sur-
prise. The wrinkling of the brows by the corrugators speaks disapproval or
bewilderment. The risorius, or grinning muscle, draws the corners of the
mouth outward. The sneering muscle lifts the nostril and lip together.
Pleasure is expressed by the lifting of the angles of the lips upward and
outward, while grief depresses them. (There are but three of the depress-
ors, or grieving muscles, on each side, and six for the manifestation of hap-
pier feelings.)

MUSCLES OF MASTICATION, FIVE IN NUMBER

The temporal muscle. — Occupying the entire temporal fossa.
Origin. — The floor of the fossa, and the temporal fascia covering
it. Insertion. — The coronoid process of the mandible.

Action. — It closes the mouth and draws the mandible or lower
jaw-bone backward.

Nerve. — Fifth cranial (or tri-facial).

The masseter. — At the side of the face (Fig. 78). Origin. —
The zygomatic arch. Insertion. — The lateral surface of the ramus
of the mandible.

Action. — It closes the mouth and moves the jaw forward
slightly.

Nerve. — Fifth cranial.

RIBBON MUSCLES 91

The internal pterygoid. — In the infra-temporal fossa covered by the
ramus of the mandible on which it is inserted.

Action. — It closes the mouth and moves the jaw forward and sideways.

External pterygoid. — Also in the infra-temporal fossa and inserted on the
mandible.

Action. — It moves the jaw forward and sideways.

Nerve. — Fifth cranial.

Buccinator. — Origin, from both the maxilla and the mandible on the
alveolar borders. The fibers approach each other, interlacing and running for-
ward; some of them join the lip muscles, constituting the insertion (Fig. 78).

Action. — It helps to close the mouth, and keeps the food between the teeth
during the act of mastication.

Nerves. — Fifth and seventh cranial.

Tempera'

Buccinato

FIG. 77. — THE TEMPORAL MUSCLE. — (Morris.')

By the action of the first four muscles the food is divided and
crushed, and also ground; the external pterygoid is especially a
grinding muscle. The function or use of these four would be
somewhat limited without the aid of the buccinator.

MUSCLES IN THE FRONT OF THE NECK

The ribbon muscles, thin and flat, connecting the larynx and
hyoid bone above, with the sternum, rib, and davicula below.

92 AX ATOMY AND PHYSIOLOGY

They are the sterno-hyoid, the sterno-thyroid, and the omo-hyoid (a
double-bellied muscle "with an intervening tendon, the inferior belly being
attached to the upper border of the scapula, the superior belly to the hyoid
bone, while the tendon between them glides through a loop of fascia attached
to the clavicula).

FIG. 78. — MUSCLES IN FRONT OF THE NECK.

i, 2, 3, Digastric muscle; 4, stylo-hyoid; 5, mylo-hyoid; 6, hyo-glossus; 7, 8, 9,
sterno-mastoid; 10, u, 12, 13, 14, ribbon muscles; 15, pharynx; 16, occipitalis; 17,
ear muscles; 18, trapezius; 19, 20, splenius; 21, levator scapulas; 22, 23, scalene; 24,
deltoid; 25, pectoralis major; 26, right platysma; 27, 28, lip muscles; 29, masseter;
30, buccinator. — (Sappey.)

Action of the three muscles. — They draw the hyoid bone and
the larynx downward, and steady them.

Nerves. — Ninth cranial, or hypoglossal.

The digastric is another double-bellied muscle (Fig. 78).

The posterior belly is attached to the mastoid process (medial surface) ;
the anterior belly to the under surface of the mandible close to the symphysis.
The intervening tendon glides through a loop of fascia connected with the
hyoid bone.

Action. — It draws the mandible downward, and opens the
mouth. (It is assisted by some other short muscles connecting the
mandible to the hyoid bone.)

Nerves. — Fifth and seventh cranial.

STERNO-CLEIDO-MASTOID 93

The mylo-hyoid (Fig. 78) is a flat muscle which forms the floor
of the mouth, being attached by one border to the inner surface of
the body of the mandible, and by the other to the hyoid bone,
which, it will be remembered, is on a level with the mandible.

Action. — It can draw the hyoid bone forward in the act of
swallowing, thus keeping the larynx out of the way of the food.

Nerve. — Fifth cranial.

The platysma. — As the muscles of the back and side of the neck are covered
by the trapezius, so those of the front and side are covered by the platysma,
which is a broad thin sheet of muscular fibers attached above to the mandible
and the fascia of the side of the face, and below to the deep fascia on the front
of the shoulder (Fig. 76). Like the face muscles, it is not covered by deep
fascia, and, since it moves the skin, it is like them a muscle of expression. It
draws the angle of the mouth downward, and strong contractions of the
muscle assist in causing an appearance as of one in a "great rage." The
action of this muscle in grazing animals is displayed when used to shake off
insects which alight upon the skin of the neck.

Nerve. — Seventh cranial.

The sterno-cleido-mastoid (Figs. 78). is the most conspic-
uous muscle in the side of the neck. Origin. — By two divi-
sions, one on the sternum (sternal, or medial origin), the other on
the clavicula (clavicular, or lateral origin). Insertion. — The
mastoid process and upper curved line of the occipital bone.

Action. — Principally to pull the mastoid process toward the
sternum and clavicula. If the right muscle contracts the right
mastoid process comes downward and forward and the chin turns
upward to the left. If the left muscle contracts the left mastoid is
pulled downward and forward and the chin goes upward to the
right. Both muscles together simply bend the head forward, or
flex it.

Nerves. — Spinal accessory (and cervical).

Clinical note. — The sterno-mastoid is another muscle which is sometimes
the seat of spasmodic contractions, causing wry-neck, or torticollis.

Levator scapulae. — The elevator of the scapula is an important muscle
in the side of the neck. Origin. — The upper three or four transverse processes.
Insertion. — The medial angle of the scapula.

Nerves. — Cervical.

94

ANATOMY AND PHYSIOLOGY

THE ABDOMINAL WALL

The abdominal wall has no bones except the lumbar vertebrae,
being mostly muscular and aponeurotic. Each lateral half is
composed of one vertical muscle in front, next to the median line;
another in the back, next to the spinal column; and three well-
developed layers having fibers of different directions, at the sides.

Rectus abdominis (Fig. 80). — This is the vertical muscle in
front. Origin. — The body of the pubes. Insertion. — The ensi-

FIG. 79. — ANTERIOR SURFACE OF THE ABDOMINAL WALL.
!> 2, 3, 7, Pectoralis major; 4, external oblique; 5, serratus anterior; 6, latissimus
dorsi; 8, xiphoid appendix; 9, 9, 15, aponeurosis of ext. oblique; 10, 14, linea alba; 1 1,
umbilicus; 12, transverse lines of aponeurosis; 13, 13, subcutaneous abdominal ring;
16, 17, 18, 19, refer to muscles of neck; 20, deltoid. — (Sappey.) Lower border of
aponeurosis is inguinal ligament.

form appendix and the cartilages of the fifth, sixth, and seventh
ribs. It is therefore narrow below and broad above, and its outer

ABDOMINAL MUSCLES 95

border is curved from the seventh rib down to the pubes. This is
indicated in the fascia over the muscle by a distinct line called
the semihmar line (linea semilunaris) .

Action. — It compresses the abdominal organs.
Nerves. — Lower thoracic and first lumbar.

Quadratus lumborum. — This is the vertical muscle at the
back (Fig. 74). Origin. — The crest of the ilium. Insertion. —
The lowest rib and transverse processes of the upper lumbar
vertebrae. It occupies the space at the back of the trunk between
the thorax and pelvis, being covered by the erector spinae and
latissimus dorsi muscles.

FIG. 80. — INTERNAL OBLIQUE AND TRANSVERSE MUSCLES.
i, Rectus abdominis; 2, 2, 3, 3, internal oblique and cut edge of its aponeurosis;
4, 4, cut edge external oblique; 5, 5, spermatic cords; 6, aponeurosis ext. oblique
turned down; 7, rectus, upper part removed; 8, 8, 9, transversus muscle; 10, umbilicus;
ii, 12, linea alba; 13, serratus anterior; 14, 15, cut edge latissimus dorsi; 17, 17,
external intercostal; 19, cut edge external oblique. — (Sappey.)

Action. — It draws the rib down and the spine to one side —
lateral flexion of the trunk.

Nerves. — Lower Thoracic.

The three layers at the side and front consist of the obliquus
externus or external oblique; the obliquus internus, or internal

96 ANATOMY AND PHYSIOLOGY

oblique; and the transversus muscles. They occupy the space
between the eight lower ribs above, and the ilium and pubes
below. Being broad and flat they do not possess tendons of the
usual kind, but many of their muscle fibers terminate in layers of
white fibrous tissue called aponeuroses, which continue to the
median line, there blending with the layers from the opposite side.
This produces a firm interlacing of white fibers called the linea
alba or -white line, stretched between the ensiform appendix above
and the body of the pubes below. It is a very strong and impor-
tant line, through which, a little below the middle, the umbilical
cord passes in the fetus; this point in the linea alba is indicated
by the umbilicus, or navel.

The external oblique (Fig. 79) is the outermost of the three
layers. Origin. — The lower eight ribs. Direction of fibers,
downward and forward. Insertion. — Some fibers on the crest
of the ilium; others in an aponeurosis which passes to the linea
alba.

Nerves. — Lower thoracic.

Special point. — The lower border of the aponeurosis of this muscle between
the spine of the ilium and the spine of the pubes is firm and unyielding, easily
felt, and important to be recognized; it is called the inguinal ligament (or
Poupart's ligament] .

The internal oblique (Fig. 80) lies underneath the external
oblique. Origin. — The lumbar fascia, crest of the ilium, and
lateral half of the inguinal ligament. Direction of fibers, upward
and forward. Insertion. — Some fibers on the lower three ribs,
others in the linea alba, and the lowest ones on the crest of the
pubes.

Nerves. — Lower thoracic and first lumbar.

The transversus (Fig. 80) is the innermost of the three layers.
Origin. — The lower six ribs, the lumbar fascia, crest of the ilium,
and lateral half of the inguinal ligament. Direction of fibers,
transversely across the side of the abdomen, toward the front.
Insertion. — In the linea alba, and the crest of the pubes. On
the pubes it is blended with that part of the internal oblique which
is attached to the same bone, making the conjoined tendon.

Nerves. — Lower thoracic and first lumbar.

Action, of the three broad muscles. — They compress the

SHEATH OF RECTUS MUSCLE 97

abdominal viscera and expel the contents of those which are
hollow.

The fibers from the inguinal ligament, of both internal oblique and trans-
versus muscles, arch downward to the pubes.

SHEATH OF THE RECTUS ABDOMINIS (FIGS. 79, 80)

In the lower fourth of the linea semilunaris, the entire thick-
ness is continued forward as one layer in front of the muscles.
In the upper three-fourths the linea semilunaris divides into two
layers which meet again in the linea alba; thus a compartment is
formed to be occupied by the rectus muscle.

This is called the sheath of the rectus, with its anterior and
posterior layers, the anterior layer being thickest and strongest in
the lower part where the greatest strain would be brought upon it.

Lineae transversae (transverse lines). — At three different levels
above the umbilicus the anterior ayer of the sheath is held down
to the rectus muscle by fibers forming transverse lines.

Note. — The location of all these markings — the semilunar line, the white
line, and the three transverse — may be seen on the surface of the body during
the action of the muscles; and in a piece of statuary representing the trunk
they should be plainly indicated (Fig. 79).

FIG. 81. — THE DIAPHRAGM.
Dotted lines indicate descent in contraction. — (H olden )

ROOF OF THE ABDOMEN

The roof of the abdomen is the diaphragm; it has no floor of
its own, the pelvic floor serving for both cavities (page no).
The diaphragm. — This is a broad, thin, dome-shaped muscle

7

98 ANATOMY AND PHYSIOLOGY

separating the abdominal and thoracic cavities. The central
portion is aponeurotic, serving for the insertion of the remaining
or muscular portion.

Origin. — i. By two vertical bundles at the sides of the lumbar
vertebrae. These vertical portions are the crura of the diaphragm.
Their fibers turn forward, crossing and interlacing before they end
in the central tendon. 2. From arches of lumbar fascia and the
lower boundary of the thorax (seventh to twelfth ribs and xiphoid
appendix).

Insertion. — In a flat central tendon, shaped like a clover leaf,
near the center of the dome. The lateral portion of the muscle arch
is higher than the central, forming a cupola on each side.

FIG. 82. — THE DIAPHRAGM, INFERIOR SURFACE.

i, 2, 3, Tendinous leaflets; 4, musele fibers; 5, 6, 7, tendinous arches; 8, 10, fibers
arising from vertebrae; n, aorta — a large artery; 12, esophagus, leading to stomach;
13, opening for vena cava. — (Potter's Compend of Anatomy.)

Action. — When the diaphragm contracts it becomes flattened,
pressing upon the abdominal organs; when it relaxes, it springs
back to its dome-shape, as high as the fourth or fifth rib, pushing
gently against the lungs. (See p. 121.)

Nerve. — Phrenic and lower intercostal.

Special points. — This muscle forms the floor of the thorax, and
at the same time the roof of the abdomen (convex floor, concave
roof). There are three openings in it at the back part for the

ILIO-PSOAS

99

passage of a large artery and vein — the aorta and vena cava, and
the esophagus.

With the muscles thus far described the walls of the cavities of
the trunk — dorsal and ventral — are completed (see page 52).

INTERIOR ABDOMINAL MUSCLES

The psoas major and iliacus. — These are two muscles within
the abdomen (on the posterior wall) which pass out over the
brim of the pelvis into the thigh.

Psoas major. Origin. — The sides of the lumbar vertebrae.
Insertion. — Trochanter minor of the femur.

4—

13

10

FIG. 83. — ABDOMINAL MUSCLES, INTERIOR.

1-5, Psoas minor and major; 6, attachment of psoas major to trochanter minor;
7, 7, 8, 8, iliacus; 9, 9, cut tendon rectus femoris; 10, 10, obturator externus; 11-13,
quadratus lumborum; 14, 14, transversus. — (Sappey.}

Iliacus. Origin. — The iliac fossa. Insertion. — With the psoas
on the trochanter minor of the femur.

Action. — They act together as one muscle, the ilio-psoas, to
flex the thigh, at the same time rotating it, so that the foot turns
outward.

100 ANATOMY AND PHYSIOLOGY

Nerves. — Lumbar and femoral.

Surgical note. — Disease of the lumbar vertebrae resulting in pus causes
psoas abscess. The pus often follows the muscle fibers downward and appears
below the inguinal ligament.

(The psoas minor is a small muscle in front of the major.)
The transversalis fascia is a layer of loose connective tissue
which completely lines the muscles of the abdomen; it is continuous
with the iliac fascia on the iliacus muscle and with the pelvic
fascia below.

CHAPTER VII
MUSCLES OF THE EXTREMITIES

The muscles of the extremities are frequently named for their
use, and they may all be grouped according to their action; as
flexors, to bend the joints over which they pass, and extensors to
straighten them; pronators and supinators; abductors and adduc-
tors; and rotators, inward or outward. Their origins are not only
from bones, but from fascia, and the fibrous septa between them.
This is true of most muscles to some extent, but particularly so
in the extremities.

The principal bony attachments only are given here.

MUSCLES OF THE UPPER EXTREMITY

SHOULDER MUSCLES

Supraspinatus. — On the dorsal surface of the scapula. Origin.
— The supraspinous fossa, the tendon passing over the head of the
humerus to the insertion on the top of the greater tubercle.

Action. — It lifts the arm away from body (abduction).

Infraspinatus. — Also on the dorsal surface of the scapula.
Origin. — The infraspinous fossa. Insertion. — The greater tu-
bercle of the humerus (below the supraspinatus).

Action. — It rotates humerus outward (the palm turns forward) .

Nerve, both muscles. — Suprascapular.

Teres minor. Origin. — The axillary border of the scapula. Insertion. —
The greater tubercle, just below the infraspinatus.

Action. — It rotates humerus outward (palm turns forward).

Nerve. — A xillary.

Teres major. Origin. — Near the ' inferior angle of the scapula (on
axillary border.) Insertion. — The shaft of the humerus (crest of lesser tuber-
cle), joining the tendon of the latissimus dorsi and acting with it (Fig. 84).

Action. — It draws the arm backward, and rotates it inward (the palm
turns backward}.

Nerve. — Subscapular (lower).

101

102

ANATOMY AND PHYSIOLOGY

10

Subscapularis (Fig. 86). Origin. — The subscapular fossa.
Insertion. — The lesser tubercle of the humerus.

Action. — It holds the head of the humerus in place and rotates
it inward (the palm turns backward}.

The deltoid (Fig. 85). — Is triangular in shape and forms a
sort of cap over the shoulder-joint. Origin. — The spine and

acromion of the scapula, and
the lateral portion of the
clavicula. Insertion. — The
lateral surface of the humerus
8 at the middle of the shaft,
2 on the deltoid tuberosity.

Action. — Principally to
.9 elevate -the humerus to a
horizontal position (acting
with the supraspinatus, an
abductor of the arm).

13

15

Nerve. — A xillary.

The serratus anterior

(Figs. 75, 85).— A large flat
and important muscle which
lies between the scapula and
the thorax. Origin. — By
...... i? separate slips from eight ribs,

on the front and side of the
thorax. Insertion.*— The ver-
tebral border of the scapula.
It lies close to the side of
FIG. 84.— MUSCLES OF THE SHOULDER. the thorax, covering a con-
i» 2. 3, 4, St Triceps; 6, attachment to siderable portion of the ribs

olecranon; 7, anconeus; 8, 8 9, deltoid (por- , intprrnstal miic:rlp<;

tion removed); 10, supraspinatus; n, infra- anc

spinatus; 12, 13, two extremities of teres Three actions. — It holds

minor (intervening portion removed); 14,

teres major; 15, latissimus dorsi; 16, 17, 18, the scapula firmly in place

I9'muslces and pulls it forward, thus

pushing the arm ahead. If the shoulders are held firmly it can
elevate the ribs, assisting inspiration. It sustains the weight of
the body when resting upon hands and knees, as in creeping.
Nerve. — Long thoracic or external respiratory.

PECTORAL MUSCLES 103

BREAST MUSCLES

Pectoralis major. Origin. — Clavicular portion, on the sternal
end of the calvicula; sterno-costal portion, on the surface of the
sternum and on six upper ribs. Insertion. — By a broad strong
tendon on the shaft of the humerus, on the crest of the greater
tubercle (Figs. 79, 85).

10 11

FIG. 85. — MUSCLES OF ANTERIOR ASPECT OF THORAX.

1-5, Pectoralis major; 6, 9, pectoralis minor; 7, subclavius; 8, deltoid; 10, anterior
portion of anterior serratus; n, external oblique; 12, 13, latissimus dorsi; 14, teres
major. — (Sappey.)

Action. — It draws the arm to the front of the thorax, opposing
the latissimus dorsi; thus it also is a "rowing" muscle.

The pectoralis minor is entirely covered by the major.

Origin. — From three upper ribs, the second, third, and fourth. In-
sertion.— The coracoid process of the scapula. Action. — It pulls the shoulder
downward. It may pull ribs upward in labored breathing or forced inspira-
tion.

Nerves of both muscles. — Anterior thoracic.

Note. — When the whole body is drawn upward by the hands,
as when hanging from a trapeze, the two pectorals, the trapezius
and the latissimus are acting together.

The subclavius is a small muscle lying in the subclavian groove between
the clavicula and first rib. It may elevate the ribs or depress the clavicula.

104

ANATOMY AND PHYSIOLOGY

ARM MUSCLES

Anterior

Biceps brachii (a two-headed muscle). Origin. — The scapula:
the long head above the glenoid fossa, and the short head on the cora-

coid process. Insertion. — By one
tendon on the tuberosity of the
radius (Fig. 86).

Nerve. — Musculo-cutaneous.

Note. — If the biceps brachii begins
to contract while the hand is pronated,
the first effect would be to pull the
radial tuberosity around and place the
hand in the supinated position, then
flexion would follow; in other words,
the biceps may act as both a supinator
and flexor.

The coraco-brachialis. — A smaller
muscle, close to the biceps. Origin. —
The tip of the coracoid process. In-
sertion.— The shaft of humerus, medial
side, opposite the deltoid.

Action. — It lifts the humerus forward.

Nerve. — Musculo-cutaneous .

The brachialis. — Is underneath the
biceps. Origin. — The anterior surface
of the humerus. Insertion. — The tu-
bercle of the ulna, just below the coro-
noid process.

Action. — With the biceps it flexes
the forearm.

Note. — This is a broad muscle and
covers the front of the elbow-joint.

N erve. — Musculo - cutaneous and
radial.

FIG. 86. — MUSCLES OF THE ARM.

*» 2i 3» S» Biceps and bicipital fas-
cia; 4, attachment of biceps to tuber-
osity of radius; 6, coracobrachialis;
7, 8, insertion of pectoralis major;
9, latissimus dorsi (insertion) ; 10, teres
major; n, subscapularis; 12, bra-
chialis; 13, 14, two heads of triceps.
— (Sappcy.)

ARM MUSCLES
Posterior FIG. 84

The triceps brachii (a three-
headed muscle). Origin. — The long head, on the scapula, just
below the glenoid fossa; the medial and lateral heads on the pos-
terior surface of the humerus, separated by the groove for the ra-

FLEXORS OF FINGERS • 105

dial nerve. Insertion. — The (top of the) olecranon process of the
ulna.

Action. — It extends the forearm (opposing the biceps).

Nerve. — Radial.

Note. — The back of the triceps is covered at its lower portion by a fibrous
layer (aponeurosis) which receives many of the muscular fibers. In action,
the three heads swell while this fibrous layer remains flat.

MUSCLES OF THE FOREARM
Anterior

The superficial flexors. — The medial epicondyle of the humerus
gives origin to a group of superficial muscles which flex the wrist
and fingers (Fig. 87).

Flexor carpi radialis, or radial flexor of the wrist. Origin. —
The medial epicondyle. Insertion. — The base of the second
metacarpal bone (that of the index-finger).

Nerve. — Median.

Flexor carpi ulnaris, or ulnar flexor of the wrist. Origin. —
The medial epicondyle and dorsal border of the ulna. Insertion. —
The base of the fifth metacarpal bone (after attachment to the
pisiform and unciform bones).

Action of the two. — To flex the wrist.

Nerve. — Ulnar.

Flexor digitorum sublimis, or superficial flexor of the fingers.
Origin. — The medial epicondyle, the upper extremity of the ulna,
and the shaft of the radius (the three long bones) Insertion. — By
four tendons, one for each finger, on the second row of phalanges.

Action. — It flexes the second joints of the fingers, but not the
finger-tips.

Nerve. — Median.

Deep flexors. — The shafts of the bones give origin to the deep
flexors of the fingers and thumb, which act upon the third row of
phalanges.

Flexor digitorum profundus, or deep flexor oj the fingers. — Is underneath
the superficial flexor. Origin. — The shaft of the ulna. Insertion. — By four
tendons, on the third or last row of phalanges.

Action. — It flexes the finger-tips.

io6

ANATOMY AND PHYSIOLOGY

16

FIG. 87. — MUSCLES OF THE FOREARM.
i, 2, 4, 4, 5, Muscles of arm; 3, tendon
of insertion of biceps; 6, round pronator;
7, radial flexor of wrist; 8, 9, palmaris
longus; 10, n, ulnar flexor of wrist; 12, 13,
brachio-radialis; 14-18, muscles and ten-
dons belonging to posterior of forearm;
19, 19, superficial flexor of fingers; 20, 20,
21, 21, tendons of the same, showing
fissure; 22,22, tendons of deep flexor com-
ing through fissure to reach the third row
of phalanges. — (Sappey.}

FIG. 88. — MUSCLES OF THE FOREARM,

DORSAL ASPECT.

i, Aponeurosis of triceps; 2, upper
end of brachio-radialis; 3, 4, long radial
extensor of wrist; 5, 6, short radial ex-
tensor of wrist; 7, 8, 8, 9, 9, extensors of
thumb; 10, 10, annular ligaments; n, 12,
12, common extensors of fingers; 13, 14,
special extensors for index and little
fingers: 15, 16, ulnar extensor of wrist;
18, ulnar flexor of wrist; 19, posterior
border of ulna; 20, olecranon process of
ulna; 21, media lepicondyle. — (Sappey.)

PRONATORS 107

Note. — Since the tendons of the superficial flexor stop at the second
phalanges, while those of the deep flexor pass to the third phalanges, there is a
fissure in each superficial tendon just before it ends, through which the deep
tendon passes forward to the bone of the finger-tip (Fig. 87).

Nerves. — Median and ulnar.

Flexor pollicis longus, or long flexor of the thumb. — Origin. — The shaft of the
radius (under flexor sublimis). Insertion. — The last phalanx of the thumb.

Action. — It flexes the tip of the thumb.

Nerve. — Median.

Note. — These tendons for the fingers and thumb lie in the
deep groove on the front of the carpus. Friction between them is
prevented by sheaths of synovial membrane — vaginal synovial
membranes.

THE Two PRONATORS, THE ROUND AND THE SQUARE

Pronator teres, or round pronator (Fig. 87).

Origin. — The medial epicondyle, and a small slip from the
ulna (coronoid process) . It passes across to the lateral side of the
radius, to the insertion at the middle of the shaft.

Nerve. — M edian .

Pronator quadratus, or square pronator.

Origin. — The shaft of the ulna. Insertion. — The shaft of the radius. It
lies just above the wrist and underneath the long muscles (close to the bones) .

Nerve. — Median.

Action of the two pronators. — They rotate the radius so as to
turn the palm downward (or backward).

One slender muscle, which is superficial to all, is the palmaris longus.
It arises on the medial epicondyle and is attached below to the palmar fascia
to keep it tense — a tensor of the palmar fascia.

Nerve. — Median.

Note. — It is understood that the muscles arising from the epicondyle
have a common tendon of origin.

Practical point. — Observe, by experimenting, that flexion and moderate
pronation are naturally performed together, and are associated in the major-
ity of the motions which are required of the upper extremity.

MUSCLES OF THE FOREARM
Posterior (Fie. 88.)

The lateral epicondyle of the humerus and the ridges above it
give origin to the muscles which extend the wrist and fingers.

108 ANATOMY AND PHYSIOLOGY

Extensor carpi radialis longus, or long radial extensor of the
wrist. Origin. — Lateral border and epicondyle of humerus.
Insertion. — The base of the second metacarpal bone.

Nerve. — Radial.

Extensor carpi radialis brevis, or short radial extensor. Origin.
—The lateral epicondyle. Insertion. — The base of the third
metacarpal bone.

Nerve. — Deep branch of radial.

Extensor carpi ulnaris, or ulnar extensor of the wrist. — Origin.
— The lateral epicondyle and dorsal border of the ulna. Inser-
tion.— The base of the fifth metacarpal bone.

Action of the three. — They extend the wrist.

Nerve.^-Deep branch of radial.

Extensor digitorum communis, or common extensor of the
fingers. Origin. — The lateral epicondyle. Insertion. — By four
tendons, on the second and third rows of phalanges, in such a way
that it can extend the bones of either row separately or both at the
same time.

The little finger has a special extensor for its tip (extensor minimi digiti).
The index finger also has a special extensor (extensor indicis), and the thumb
has three — two for its phalanges, and one for its metacarpal bone. By forci-
bly extending the thumb these three tendons are brought into view, the one for
the tip of the thumb being at a little distance from the other two; thus they
bound a little hollow which has been called the "anatomic snuff box."

Nerves of all. — Deep branch of radial.

THE Two STJPINATORS

The supinator. Origin. — The lateral epicondyle and upper
end of the shaft of the ulna. It winds around the head and neck
of the radius to the insertion on upper part of the shaft ; This is
the chief supinator; it is entirely covered by other muscles.

Action. — It rotates the radius and turns the dorstim 01 the
hand downward or backward.

Nerve. — Deep branch of radial.

The branchio-radialis (Fig. 87). Origin. — The lateral border
of the humerus. Insertion. — The styloid process of the radius.

THENAR AND HYPOTHENAR MUSCLES IOQ

Action. — It assists in both flexion and supination of the forearm.
(This muscle was formerly called the long supinator.)

Nerve. — Radial.

Annular Ligaments

These are special bands of deep fascia holding in place those
tendons which pass the wrist-joint. They include the tendons in
canals through which they glide freely. Friction is prevented by
synovial sheaths within the canals. The fascia which binds down
the extensor tendons is the dorsal ligament of the wrist; that which
confines the flexor tendons is the transverse ligament of the wrist.

MUSCLES OF THE PALM (Fio. 87)

There is a group of palmar muscles which move the thumb in
various directions (flexion, abduction, adduction, and so on).
They form the elevation called the thenar eminence, or the "ball
of the thumb." A similar group for the little finger forms the
hypothenar eminence.

They arise mostly on carpal bones and deep fascia and are inserted on first
phalanges. In the hollow of the hand between these two eminences lie the
long tendons, already described, on their way to the fingers; also some small
muscles between them and beneath them.

The interosseous muscles fill the interosseous spaces. The action of the
dorsal group is to spread the fingers apart (abduction) while that of the palmar
group is to bring them together (adduction).

Note. — A line drawn from the middle of the wrist to the tip of the middle
finger is called the median line of the hand. To abduct the fingers and thumb
is to draw them away from this line — in other words, from the middle finger.
To adduct them is to draw them toward the middle finger.

Nerves. — To the hypothenar muscles. — Ulnar. To thenar muscles. —
Median and ulnar. To inter ossei. — Ulnar.

The muscles in the palm are covered by particularly dense,
deep fascia called the palmar fascia, or palmar aponeurosis.

MUSCLES OF THE LOWER EXTREMITY

The Pelvis — Interior

False pelvis. — The iliacus is the only muscle in the false pelvis;
it is already described with the psoas major, page 99.

no

ANATOMY AND PHYSIOLOGY

True pelvis. — The piriformis and obturator interims. These
muscles arise from the interior of the pelvis and pass out through
the sciatic notches — the piriformis through the greater notch and
the obturator internus through the lesser notch. They are
inserted on the great trochanter and act to rotate it outward.

They are supplied by nerves which are branches of the sacral
plexus.

They are short muscles but thick and very strong.

The floor of the pelvis consists of two flat muscles on either side,
the levator ani and the coccygeus.

-Sacrum

pirifonnis

Coccyx

Levator ani (di-
vided below
the "white
line")

Space for obtu-
rator internus

Rectum
Prostate

Symphysis

Passage for tfu-
teal vessels
and nerve

Pirifonnis

Passage for sci-
atic and pu-
dic vessels
and nerve

Ischial spine

Coccygeus
CcJlular interval

Levator ani

Capsule of pros-
tate, arid pu-
bo- prostatic
ligaments

FIG. 89. — INTERIOR AND FLOOR OF THE TRUE PELVIS. — (Morris.)

The origin is on the interior of the pelvic wall — that is, on
the pubic bone and the spine of the ischium, and a line of fascia
between the two points. Insertion. — The muscles meet each
other in the median line, being also attached to certain pelvic
organs (bladder and rectum in the male; bladder, rectum, and
vagina in the female) and to the coccyx. Their action supports
the pelvic organs, especially the rectum, and lifts them in various
motions of the body, as in respiration.

Nerves. — From sacral nerves.

Special notes. — These two muscles form a concave floor like an inverted
dome, which is the pelvic diaphragm. When this dome contracts it rises.

There are two openings in the pelvic floor for the bladder and rectum, and
a third opening in the female pelvis for the vagina.

GLUTEUS MAXIMUS

III

The pelvic fascia is a continuation of the transversalis fascia
which lines the abdomen and of the iliac fascia which covers the
iliacus muscle. It covers the obturator muscle and its fascia and
the muscles of the floor, and forms ligaments for the pelvic viscera.

THE PELVIS — EXTERIOR

Three gluteal muscles. — From the three gluteal lines of the os
coxae and the spaces above them, arise three gluteal muscles.

Gluteus minimus. Origin. — The in-
ferior line and space above it. Insertion.
— The front of the great trochanter.

Action. — It abducts the thigh and ro-
tates the femur slightly inward (so that
the foot turns in).

Gluteus medius. Origin. — The an-
terior or middle line and space above it
up to the crest. Insertion. — The outer
surface of the great trochanter.

Action. — Abduction of the femur and
some rotation outward.

Nerve of both. — Superior gluteal.

Gluteus maximus. Origin.—
The posterior line and space behind
it to the crest (also from the back
of sacrum). Insertion. — The back
of great trochanter and the ridge
below it, also the deep fascia, or
fascia lata.

Action. — External rotation of the
femur; it is also a powerful exten-
sor of the hip-joint when one rises from the sitting position, or
in mounting steps. It also abducts the- thigh.

Nerve. — Inferior gluteal.

Obturator externus. Origin.— The obturator membrane and bone around
it. Insertion. — The fossa of the great trochanter. Action. — External rota-
tion of the femur. (Fig. 83.)

FIG. 90. — THE GLUTEUS MAXIMUS.
(Fascia removed.) — (Sappey.)

Nerve. — Obturator.

112

ANATOMY AND PHYSIOLOGY

Practical point. — Observe the number of muscles for external
rotation and note that the usual position of the foot is with the
toes turned outward.

6,

FIG. 91 MUSCLES OF THE

THIGH.

MUSCLES OF THE THIGH
Anterior

On the front and the sides of the
femur are the muscles which extend the
leg — four in number; they blend at their
insertion and therefore constitute a four-
headed muscle, the quadriceps femoris.
They are the rectus femoris, the vastus
lateralis, vastus medialis and the vastus
intermedius.

Rectus femoris. Origin. — The an-
terior inferior spine of the ilium and the
upper border of the acetabulum. The
three vasti. Origin. — On the linea as-
pera and the three surfaces of the femur.
Insertion oj the four. — By one tendon
passing in front of the knee-joint to the
tubercle of the tibia. (It encloses the
patella and has been improperly called
the ligamentum patellae.)

Action. — They extend the leg as in
walking, or with great force in kicking;
these muscles also keep the patella in
place during various positions of the
knee.

Nerve. — Femoral.

The sartorius. — The longest muscle

i, 2, Iliacus and psoas; 3,
4, tensor fascia latae: 5, sar- in the body; it passes across the front

£±! 6la.S! T&i of the quadri«Ps- Origin.-The ante-

medialis; 9, gracilis; 10, ad- rior superior spine of the ilium. Inser-

ductor longus; ii, pectineus. ,. ,„, . , , ,, ,.,.

—(Sappey.) tion. — The inner surface of the tibia,

just below the head.

Action. — Since it passes across to the medial side of the thigh,
and behind the medial epicondyle, it flexes the leg and at the

HAMSTRING MUSCLES

same time lifts it in such a way that when both legs are acted
upon together, they'' are flexed and crossed, hence the name,
signifying "tailor" muscle.
Nerve. — Femoral.

The tensor fasciae latae. — Is attached
to the anterior part of the crest of the
ilium between two layers of the fascia lata;
it makes tense the lateral portion of the
fascia which is connected with the tibia,
or the ilio-tibial band. (This is felt like
a strong cord above the lateral epicon-
dyle.) It also rotates the thigh inward
(Fig. 91).

Nerve. — Superior gluteal.

MUSCLES OF THE THIGH

Posterior

The muscles are three in num-
ber— the biceps femoris, semitendi-
nosus, and semimembranosus (Fig.

93).

The biceps femoris. Origin.—
Long head on the tuber of j the is-
chium, short head on the linea as-
pera (lateral lip). Insertion. — The
head of the fibula.

The semitendinosus and the
semimembranosus also arise on
the tuber of the ischium, and are
inserted on the tibia, medial sur-
face and back of head. (Their
names indicate their shape, one
being tendinous in half its length, Xf 2> 3> ^ IliacuS( psoas> ^

and the Other aponeuro tic, or mem- tor, piriformis; 5, gluteus maximus;
i » \ 6, sartorius; 7, gracilis; 8, semitendin-

branous .)

Action.' — These three muscles
act together to flex the knee.

Nerve to the three. — Sciatic.

Notes. — They also assist the gluteus maximus to extend the
thigh, as in rising from a chair. The biceps tendon may be felt
8

FIG. 92. — MEDIAL ASPECT OF THE
THIGH AND PELVIS.

osus; 9, semimembranosus; 10, n,
12, tendons of sartorius, gracilis, and
semitendinosus; 14, tendon of semi-
membranosus.— (Sappey.)

ANATOMY AND PHYSIOLOGY

Fascial insertion of
gluteus marimus

Biceps

Vastus lateral! s

Plantari

Gastrocnemius

oleus

Peroneus longus-

Sfmi-membranosus

Semi-tendinosus

Gracilis

Tendon of semi-membranosus

Sartorius

Flexor digitorum longus

Tendo Achillis

FlG. 93. — POSTERIOR OF THIGH AND LEG AND HAMSTRING TENDONS. — (Morris.)

POPLITEAL SPACE '

behind the lateral epicondyle; the two others, behind the medial
epicondyle, making the borders of a deep space — the popliteal
space, or ham. They are called "hamstring" tendons.

f Lateral side, biceps femoris.

Hamstring tendons.

Medial side

The popliteus is a flat muscle behind the knee-
joint, forming part of the floor of the popliteal space.

The most important muscles in the me-
dial side of the thigh are the four adductors
(Fig. 94).

The adductor longus. Origin. — From the su-
perior ramus of the pubes. Insertion. — The mid-
dle of the linea aspera.

The adductor brevis. Origin. — Upper part of
the pubic arch. Insertion. — The linea aspera be-
hind and above the longus.

The adductor minimus. Origin. — The lower
part of the pubic arch. Insertion. — The linea
aspera, behind the brevis (upper part).

The adductor magnus. Origin. — Pubic arch
and tuber of the ischium. Insertion. — Linea as-
pera (behind the others), and medial epicondyle.

Action of the four.- — They all adduct the
femur (rotating it outward) and draw the
thighs together as in horseback riding.

Nerve to the four. — Obturator, and great sciatic to
a portion of adductor magnus.

Note. — The magnus makes a broad sheet of mus-
cle between the quadriceps which extends the knee,
and the muscles on the back which flex it. The
longest and strongest fibers of the magnus run between
the tuber of the ischium and the medial epicondyle.
They rotate the femur inward.

semitendinosus.
semimembranosus.
sartorius.
gracilis.

FIG. 94. — ADDUCTORS.
i, 2, 3, Femur, ilium,
pubes; 4, external obtu-
rator muscle; 5, 6, 7, 8,
9, 10, adductor muscles;
ii, 12, openings for ves-
sels passing to back part
of thigh.— (Sappey.)

MUSCLES OF THE LEG

Anterior

These muscles flex the ankle and extend the toes.1
The muscles in the front of the leg are between the tibia and the

1 Note. — These movements are dorsal flexion.

n6

ANATOMY AND PHYSIOLOGY

fibula; the medial surface of the tibia, having no muscles upon it,
is called subcutaneous.

The tibialis anterior. Origin. — The shaft and head of the
tibia (lateral surface)^and the interosseous membrane.

Insertion. — The first cuneiform and first
metatarsal bones.

Nerve. — Deep peroneaL

The peroneus tertius. Origin. — The shaft
of the fibula (lower part). Insertion. — The
fifth metatarsal bone.

Action of the two. — To flex the ankle. The
tibialis acting alone lifts the medial border of
the foot; the peroneus lifts the lateral border.

Nerve. — Deep peroneal.

The 'extensor hallucis longus, or long ex-
tensor of the great toe. Origin. — The shaft of
the fibula and the interosseous membrane.
Insertion. — The last phalanx of the great toe.

Action. — To extend the great toe.

Nerve. — Deep peroneal.

The extensor digitorum longus, or long
extensor of the toes. Origin. — The shaft of
the fibula and interosseous membrane (a few
fibers from head of tibia). Insertion. — By
four tendons on the second and third pha-
langes of the four lateral toes, like the similar
extensor of the fingers.

Action. — To extend the toes.

Nerve. — Deep peroneal.

Note. — These two muscles, since they pass
in front of the ankle-joint, flex it.

FIG. 95. — MUSCLES
OF THE LEG, ANTERIOR.

i, Rectus femoris; 2,
tibia; 3, tibialis ante-
rior; 4, long extensor
of toes; 5, long extensor
of great toe; 6, peroneus
tertius; 7, 8, peroneus
longus, p. brevis; 9, 10,
lateral and medial
heads, gastrocnemius;
ii, short extensor of
toes; 12, annular liga-
ment. — (Sappey.)

On the dorsum of the foot the extensor digitorum brevis has four slender
tendons for the four medial toes.

Nerve. — Deep peroneal.

MUSCLES OF THE LEG

117

MUSCLES OF THE LEG

Posterior

These muscles extend the ankle and flex the toes; they all pass
behind the medial malleolus. They are covered by the calf muscles.

The tibialis posterior. Origin. — Shaft of both tibia and fibula and the
interosseous membrane. Insertion. — Navicular and first cuneiform bones.

Action. — Extension of the ankle.

Nerve. — Tibial.

The long flexor of the great toe, or flexor hallucis lon-
gus.— Origin. — Shaft of fibula. Insertion. — Last phalanx
of the great toe (Fig. 96).

Nerve. — Tibial.

Long flexor of the toes, or flexor digitorum longus.
— Origin. — Shaft of fibula. Insertion. — By four tendons
on the last phalanges of the four lateral toes (Fig. 96).

Action of these two muscles. — Flexion of the tips of
the toes.

Nerve. — Tibial.

LEG — LATERAL SIDE (FiG. 97)

Peroneus brevis. Origin. — Shaft of fibula.
Insertion. — Base of fifth metatarsal bone. The
tendon passes behind the lateral malleolus.

Peroneus longus. Origin. — Shaft of fibula.
Insertion. — In the sole of the foot, first cuneiform
and first metatarsal bones. The tendon passes DLE LAYER-
behind the lateral malleolus and crosses in the
sole to the medial border of the foot. '/« dividing into

four tendons; 3, ten-

Action of these two muscles. — They extend don of long flexor of
the ankle and lift the lateral border of the foot. |7pianSr4muscles|

9, projection of fifth

Nerve to both.— Superficial peroneal. metatarsal bone; 10,

sheath of tendon of

Note. — As the tibialis anterior and pero- peroneus longus; n,
neus tertius flex the foot, so the tibialis pos- c

FIG. 96.— Mus-
REGION, MTD-

terior and peroneus brevis extend it.

Orthopedic note. — The P. longus makes a chord for the
transverse arch of the foot, being the most important muscle to
preserve that arch from being flattened.

n8

ANATOMY AND PHYSIOLOGY

CALF MUSCLES (Fics. 93, 97)

Triceps surse, and plantaris.

The gastrocnemius. Origin. — By two heads just above the
condyles of the femur. Insertion. — On the calcaneus.

Note. — The two heads form the
lower boundaries of the popliteal
space.

The soleus is covered by the gas-
trocnemius. Origin. — Medial border
. of the tibia and lateral border of the
fibula. Insertion. — The os calcis,
with the above muscle.

Action of the two. — They join to
form one muscle, the triceps surse (or
triceps of the calf), which has the
strongest tendon in the body, the tendo
calcaneus (tendon of Achilles} by
which they are attached to the os
calcis, and, therefore, they lift the heel.
If the muscles of both legs act at the
same time, the whole body is lifted on
the toes.

Nerve to both. — Tibial.

The plantaris. Origin. — With the outer
head of the gastrocnemius. Insertion. —
With the tendo calcaneus.

Note. — The belly is short and small; the
tendon is the longest in the body.

The calf muscles constitute a group
of great power, as by them one lifts
oneself to stand upon the toes.

The sole of the foot, or plantar
region, resembles the palm of the
hand in having special groups of mus-
cles for the great and little toes, with the long flexor tendons
lying between them, and a dense fascia covering them. This is
called the plantar fascia.

The nerves are medial and lateral plantar.

FIG. 97. — LATERAL ASPECT AND
CALF OP LEG.

J» 2, 3, 4, Lateral view, mus-
cles passing in front of ankle; 5,
6, peroneus brevis and p. lon-
gus (behind ankle); 7, 8, soleus
and gastrocnemius; 9, head of
fibula; 10, biceps femoris; u,
semimembranosus; 13, tendo
Achillis; 15, annular ligament;
16, 17, insertions of peroneus
tertius and brevis; 18, short ex-
tensor of toes; 19, plantar mus-
cle; 20, patella. — (Sappey.)

PHYSIOLOGY OF MUSCtES IIQ

Annular Ligaments

The tendons which pass from the leg to the foot are kept in
place by special ligaments, anterior and lateral, and surrounded by
synovial sheaths as in the wrists.

POINTS. — Eversion of the foot, or lifting the medial border, is done by the
tibialis anterior.

Inversion. — Or lifting the lateral border, by the peroneus tertius, and
peroneus longus.

Adduction. — By deep posterior muscles of the leg.

Abduction. — By lateral muscles of the leg.

RESUMES .

Observe certain similarities and differences in the extremities.
Extension of the elbow is accomplished by the three-headed muscle,
the triceps. Extension of the knee requires a powerful four-headed
muscle/ the quadriceps.

The great toe is on the medial border of the foot, the thumb is
on the lateral border of the hand. This is so because the terms
medial and lateral are applied to the pronated position of the lower
extremity and the supinated position of the upper extremity.

In the upper extremity the joints are all flexed in one direction,
as though the limb might be rolled up. In the lower extremity
they flex and extend alternately, as though the limb were folded
back and forth.

STRUCTURE AND PHYSIOLOGY OF MUSCLES

A complete muscle is a complicated structure. It consists of:

First, the essential muscle substance in the muscle cells, p. 83.

Second, connective tissue wrappings and partitions.

Third, tendons or aponeuroses, or both.

Fourth, blood- and lymph-vessels in great abundance.

Fifth, muscle nerves.

The connective tissue supports all of the other structures and
protects the muscle, preserving its shape and stability.

The tendons and aponeuroses provide a means whereby the
attachment to other organs is kept within a small space.

EXAMPLE: The biceps of the arm contains many fibers, but the slender
tendons of this muscle occupy only small areas upon the surface of the bones.
The aponeurosis of that very powerful muscle, the quadriceps femoris, receives

I2O

ANATOMY AND PHYSIOLOGY

the insertion of the muscle fibers, and by this means only a narrow surface
is required for insertion upon the bone. But for arrangements like these,
the skeleton would of necessity be inconveniently large.

The blood-vessels bring the nutritive fluid which, in the tissue-
spaces, bathes each little fiber, and is gathered up by the lymph-
vessels. One-fourth of the blood in the body is in the muscles.

The nerves bring to each fiber its natural stimulus to action.

The work of muscle tissue is done in the fiber cell. This,
when stimulated, contracts, bringing the two ends of the fiber
nearer to each other, and naturally the fiber swells as it shortens.
So with the myriad of fibers in a muscle; when they contract, the
muscle swells and shortens (Fig. 98) illustrates the changes pro-

FIG. 98. — SHOWING CHANGE OF SHAPE IN CONTRACTION. — (Brubaker.)

duced). This results in motion, which appears as the organs
attached are moved. One-third of the body weight is muscle
tissue.

All skeletal muscles are so attached as to be tense, that is, they
are just a little stretched, so that it is easier for them to act than
not. (A cut across a muscle releases it from tension and leaves a
gaping wound.) See p. 123, tension and tonus.

The actions of muscles are regulated by their attachments, and
the function is often expressed in the name. If muscles or their
tendons pass in front of a joint, for instance, causing flexion, they
are frequently called flexors; or if they pass behind such joints,
they may be called extensors; and so with other muscles and joints.
Examples: Flexors of the wrist, extensors of the fingers, etc.
Many other examples will occur to the student, as abductors,
adductors, pronators, etc.

ACTION OF DIAPHRAGM . 121

As the location determines the function of a muscle, so it often
suggests the name, as the pectoralis major and minor, the inter-
costals, etc. Sometimes the shape is named, as the orbicularis of
the mouth or of the eyelids (orbicular muscles, or sphincters,
surround and control openings) . Shape and location may together
suggest a name sometimes, as the latissimus dorsi, the rectus
abdominis (broadest of the back and straight of the ab-
domen) and others, expressing or implying the function of the
muscle.

One of the most useful and interesting muscles in the body is the
diaphragm. Although a voluntary muscle in structure, it is asso-
ciated with visceral action. (For general description see page 98.)

The special interest attending this muscle arises from its
location as well as its structure. Situated between the great
cavities of the trunk it acts upon the organs belonging to both.
In contraction, it encroaches upon the cavity of the abdomen
pressing upon abdominal organs, and thus aids in expelling the
contents of abdominal and pelvic viscera. In this act (expulsion
from abdomen or pelvis) it is fixed in contraction (holding the
breath) so that other muscles can act efficiently. Examples:
defecation, parturition. Ceasing to contract it returns to its inac-
tive or dome-shape; and as this is accompanied by slight ab-
dominal pressure upward, the effect upon the thorax is to shorten
it, causing gentle pressure upon the lungs.

In contraction, therefore, it compresses the abdomen and
enlarges the thorax; in relaxation, it enlarges the abdomen and
compresses the thorax. This alternate enlargement and com-
pression of the thorax explains its most important function — that
of a breathing muscle, especially a muscle of inspiration.

Special points. — The lateral portions of the diaphragm are the
most movable portions, being mostly muscular. Here the lungs
rest upon the falling and rising floor, themselves alternately ex-
panding and contracting. The heart lies upon the least movable
portion — consequently the diaphragm supports the heart but does
not press against it unless pushed up from below.

Similar functions pertain to another muscle constituting the
floor of the pelvis (the levator ani and coccygeus taken together),
which rises and falls with the displacement and functionating of
abdominal organs. With the combined contraction of these two,

122 ANATOMY AND PHYSIOLOGY

and relaxation of the diaphragm, the whole body of abdominal and
pelvic organs moves upward, and vice versa.

Passing to the consideration of more complicated movements.
For respiration we must have the muscles of the thorax; for
swallowing or deglution, the muscles of the tongue and throat; for
speaking, those of the tongue and face.

The arms and hands become organs of prehension when by use
of their numerous muscles they reach out to gather things in; the
lower limbs are organs of locomotion, only because their muscles
enable them to bear and transport the body from place to place.
Even the ability to stand still is due to a balanced tension of mus-
cles, which keeps the joints quiet.

Finally, various emotions may be expressed by muscle-action
without a spoken word, both by changes of the face (referred to,
p. 88) and gestures of the body. Compare the erect posture of
the person ready and alert, with the drooping figure of despond-
ency or the lax one of indolence. Read the meaning of the firm,
quick footstep, and contrast it with the uncertain and halting
one. Note how the hand may welcome, or repel. Even the eye
would be far less expressive were the iris immovable. Indeed,
we might well see a literal meaning in the old adage — "Actions
speak louder than v words." Thus muscle action means much
more than simple movement, and it all depends ultimately upon
the specially developed attributes of the muscle cell — contractility,
extensibility, elasticity.

And thus we find that all functions of the body depend in the
beginning upon muscle action, as the heart itself is a collection of
muscles influencing the entire body, since without circulation of
blood all processes of life must cease.

Muscle Stimulus. — The action of skeletal muscles as we
ordinarily see them, expresses the result of the response of muscle
tissue to the natural and direct stimulus of nerves. (Nerve im-
pulses1 originate in the brain and spinal cord in response to sense
impressions, and will be studied in connection with the nervous
system.) Certain other stimuli cause temporary muscle action —
for example, the contact of acids (chemical} , a sharp blow (mechan-
ical}, electricity, etc.

Allusion has already been made to the tension of muscles pro-

1 An unsatisfactory term, but in common use.

MUSCLE TONE 123

duced by the slight stretching of their attachments, as though the
bones had outgrown them a very little. The tension is in itself
a stimulus, and is increased by what is called normal muscle
tone.

Slight contractions of fibers are continually going on, caused
by various delicate stimuli — so delicate that we are not always
conscious of them although the muscle is; these contractions
constitute muscle tone (tonus) which is important in several ways.
First, it holds the muscles ready for instant action, making labor
easier; second, it maintains a steady, although slight, production
of body heat; third, it assists the steady flow of circulating fluids
— blood and lymph; and fourth, it maintains favorable conditions
in internal organs for the processes of secretion and excretion.

Although unconscious of normal muscle tone, we can often
recognize the increase of tone. One example is the effect of
cold; shivering is an instance of exaggerated muscle tone (it is
however somewhat complex). Again, some emotions — as fear,
anger, joy, sorrow, surprise, etc., always increase muscle tone. The
expression "all strung up" is in a sense accurate, if not elegant.
Also, an attitude of sustained attention produces the same effect
and is often prolonged to the verge of conscious fatigue. Some
idea of the degree of energy exerted in maintaining increased tone
may be derived from the feeling of languor which follows it;
people often speak of feeling the "relaxation" after excitement.

In all of these conditions, the heart is quickened more or
less; and, in short, whatever cause, mental or physical, increases
the rapidity of the circulation, will contribute to an increase of
muscle tone, by preserving nutrition and removing waste matters.

Diminished tone is the result of overuse or of poor nutrition —
either of nerve or of muscle, or both — the effect being a tired
feeling, or manifesting itself in various ways, such as inability
to work, physical and mental inefficiency, etc. The need of a
"tonic," or to be "toned up," is a common complaint.

Rest is necessary for the restoration of muscle tissue after work,
in the ordinary activities of life, and still more after excessive
exercise, in order that the renewal of muscle plasma may
be accomplished and a store of material laid up for further
use. This cannot be brought about while the muscle is doing
visible work.

124 ANATOMY AND PHYSIOLOGY

Massage is beneficial in conditions of nerve-muscle tire, because
it improves the circulation while the patient is in a passive state,
so that better nutrition is secured and accumulated waste re-
moved, without the necessity for effort by the patient. (The
same is true of bruises and sprains.) No bad results will follow
moderate overuse, provided sufficient rest be promptly secured.
The expression "a healthy tire" is a logical one, because by
reasonable use a muscle grows, if suitable resting time is secured.
Beyond a reasonable limit, however, overuse is injurious; the
muscles work irregularly, perhaps painfully; nutrition declines;
wastes accumulate, and the will is no longer in control. Writer's
cramp is a familiar example.

The various stations and postures of the body are made
possible by properly adjusted muscle groups, which enable us to
preserve- our balance in different positions. It is here that the
extensibility and elasticity of muscle tissue are of greatest impor-
tance. Sitting and standing, as well as walking and running,
are states of activity, whereby the flexor and extensor muscles
(and associated groups) oppose each other in equilibrium. It is
truly "hard work to keep still."

The activities of muscles and nerves are so closely associated
that they cannot be well understood apart, and will be further
studied in Chapters XX and XXI.

Rigor Mortis. — It is already stated that muscle fibers are
composed of muscle cells ; the cell consists of muscle plasma
encased in a delicate substance called sarcolemma. The plasma
contains minute fibrils and various nutrient substances, mostly
proteins (page 153). Upon the death of the body coagulation of
muscle plasma occurs and certain proteins are separated from the
plasma in the form of a clot. (Myosin and Myogen fibrins.}
This coagulation results in a firm contraction of the muscle fibers,
and a general rigidity, called rigor mortis. It appears first in the
muscles of the lower jaw, and, advancing downward, gradually
involves the upper extremities and the whole body.

In the case of chronic disease, or of defective blood supply,
the rigor appears soon (it may be as early as fifteen minutes) and
passes soon. After an acute disease it appears late and lasts longer.

The disappearance of rigor mortis is due to the formation of
acids in the muscle fiber, which soften the fiber.

TETANUS, CRAMP, FATIGUE 125

MUSCLE TISSUE, A SOURCE OF HEAT AND ELECTRICITY

Thus far we have considered only one result of muscle action ;
namely, the production of motion. Muscle tissue is built up of
food derived from the blood- — contraction means a using up of its
substance, and the formation of waste products. These chemical
processes are going on continually, and all chemical action is ac-
companied by the production of heat. A muscle in action is there-
fore a machine for producing body heat, and since the muscular
system comprises so large a portion of the human body (weighing
nearly three times as much as the bones), it is one of the chief
sources of heat; for the double reason that it includes a great deal
of tissue, and that it is more constantly at work than any other
tissue in the body.

We all know that the body temperature rises during muscular
exercise; as the vessels dilate, bringing oxygen for chemical action,
heat is rapidly evolved and waste is swept away. (Blood- and
lymph vessels carry both food and waste.)

In addition to other results of muscle activity, a slight current
of electricity is produced, appreciable only by certain experiments.

MODIFICATIONS OF MUSCLE ACTION

Clinical notes. — Tetanus is a condition of the muscles in which
the contractions are so rapid that the action appears to be con-
tinuous; the stimuli come so rapidly that the fibers cannot perfectly
relax.

It may be due to various causes: to drugs, as strychnine; to
bacterial poisoning through invasion of wounds ; or to disordered
conditions of the nerve system. It may be voluntary in char-
acter; when one deliberately stiffens the body or. any portion of
it the rigidity thus occurring is tetanic.

Cramp is sudden involuntary contraction of muscle-fiber,
spasmodic in character and so violent as to be exceedingly painful.

Convulsive movements or convulsions (spasms} are due to invol-
untary and forcible action of several muscles or groups of muscles.
The movements vary with the number of muscles involved.

Fatigue of muscle tissue follows prolonged use, evidenced by
sensations of pain in the muscles themselves, probably due to an
accumulation of waste matters when the muscle is not quite equal

126

ANATOMY AND PHYSIOLOGY

to the demands made upon it; repair does not keep pace with
wear and the muscle becomes not only tired from overwork and
lack of food but burdened with the poisons of fatigue.

LARGE MUSCLES CLASSIFIED ACCORDING TO THEIR MOST
FREQUENT ACTION

REGION.

ACTION.

MUSCLES.

TRUNK

To enclose cavities and aid

in respiration

Intercostals.

To separate cavities and
aid in respiration

Quadratus lumborum.
Obliquus externus.
Obliquus internus.
Transversus.
Rectus abdominis.

Diaphragm.

Floor of 'trunk and aiding
above muscles

Levator ani.

HEAD

To move spine and trunk. .
To extend head

Coccygeus.
Abdominal group.
Erector spinae.
Ilio-psoas.
Erector spins.

To flex head

Trapezius.
S terno-mastoids.

To rotate head

Trapezius.

SHOULDER

To lift shoulder

Sterno-mastoid.
Trapezius.

To pull shoulder backward
To pull shoulder forward. .

Trapezius.
JlnJt£riQr_serratus.

ARM

To pull arm forward

Pectorals

To pull arm backward
To abduct (lift) arm

Latissimus dorsi.
Deltoid.

FOREARM

To adduct (pull downward)
To rotate arm, supination
To rotate arm, pronation
To flex forearm

Suprascapular.
Pectorals.
Latissimus dorsi.
Infraspinatus.
Teres minor.
Subscapularis.
Teres major.
Biceps brachii.

To extend forearm

Brachialis.
B rachio-radialis.
Triceps.

To rotate, supination

Supinator.

To rotate, pronation

Biceps brachii.
Brachio radialis.
Pronator teres.

Pronator quadratus.

ACTION OF MUSCLE GROUPS

127

LARGE MUSCLES CLASSIFIED ACCORDING TO THEIR MOST
FREQUENT ACTION.— (Continued)

REGION.

WRIST.

HAND.

THIGH.

ACTION.

MUSCLES.

To flex wrist

To extend wrist.

To flex fingers. .

To extend fingers.

To flex thumb....
To extend thumb .

To flex thigh

To extend thigh

(also to extend trunk)

To rotate outward.

To rotate inward.

LEG.

To abduct.
To adduct.
To flex leg.

To extend leg.

ANKLE.

FOOT.

Rotation outward.
Rotation inward. .
To flex ankle. .

To extend ankle.
To flex toes. .

To extend toes.

Flexor carpi radialis.
Flexor carpi ulnaris.
Extensor carpi radialis

(long and short).
Extensor carpi ulnaris.
Flexor digitorum (sub-

lim.).

Flexor digitorum (pro-
fund.).
Extensor digitorum

(com.).
Extensors of index and

little fingers
Thenar group.
Three extensors of

thumb.
Ilio-psoas.
Gluteus maximus.
Biceps femoris.
Semitendinosus.
Semimembranosus.
Glutei-med. and min.
Sartorius.
Four adductors.
Two obturators.
Gluteus min.
Tensor fasciae latae.
Adductor magnus (long

fibers of).
Three glutei.
Four adductors.
Biceps femoris.
Semitendinosus.
Semimembranosus.
Sartorius.
Quadriceps femoris (rec-

tus and three vasti).
Sartorius.
Biceps.
Tibialis ant.
Peroneus tertius.
Tibialis post.
Peronei (long and short).
Flexor digitorum

(longus).

Flexor pollicis (longus).
Extensor digitorum

(longus).
Extensor hallucis

(longus).

128 ANATOMY AND PHYSIOLOGY

SPINAL NERVE SUPPLY TO PRINCIPAL MUSCLE GROUPS

REGION.

MUSCLES.

NERVE.

SIDE OF NECK.

THORAX AND SHOULDER

Three scaleni muscles.
Elevator of angle of scapula

Intercostal

Diaphragm

Sacro-spinalis (erector

spinae) !

Latissimus dorsi :

Supra- and infraspinatus. .
Subscapularis.

Teres major

Teres minor

Deltoid. .

ARM, ANTERIOR

Pectoralis major and minor
Biceps.

Coracd-brachialis

Brachialis. .

ARM, POSTERIOR Triceps

FOREARM, POSTERIOR. Supinators and extensors
of wrist

Extensors of fingers

FOREARM, ANTERIOR . . Pronators and superficial
flexors ;

Flexor carpi ulnaris and
deep flexors

(The deep flexor of fingers
has also a branch from
median.)

HAND Thenar eminence (muscles

of thumb)

Hypothenar eminence
(muscles of little finger) . .

Interossei

ABDOMEN AND PELVIS. Rectus and pyramidalis.

Quadratus lumborum.

External and internal ob-
lique.

Transversus.

Psoas and iliacus

Levator ani.

Perinea! muscles

Piriformis

Gluteus maximus

Gluteus medius and mini-
mus.

Tensor fasciae latae

Obturators, external and
internal . .

Cervical branches of bra-
chial plexus.
Intercostal.
Intercostal and phrenic.

Spinal.

Long subscapular.

Suprascapular .

Subscapular.
Axillary.

Axillary and ant. tho-
racic
Ant. thoracic.

Musculo-cutaneous.
Musculo-cutaneous and
radial.

Radial (musculo-spiral).
Deep branch of radial.

Median.
Ulnar.

Ulnar and median

Ulnar.
Ulnar.

Thoracic and lumbar

Pudic.

Sacral plexus.
Inferior gluteal.

Superior gluteal.
Obturator.

NERVES OF SKELETAL MUSCLES

129

SPINAL NERVE SUPPLY TO PRINCIPAL MUSCLE GROUPS —

(Continued)

REGION.

MUSCLES.

NERVE.

THIGH • Three adductors.

Gracilis. .

THIGH, ANTERIOR — • Quadriceps.

rectus.
two vasti.
crureus..

THIGH, POSTERIOR ...• Biceps.

Semitendinosus.

Semimembranosus

LEG, ANTERIOR Anterior muscles (exten-
sors)

LEG, LATERAL.

Peroneus longus and brevis

LEG, POSTERIOR Calf muscles.

Deep muscles (flexors).. . .
FOOT Dorsum

Plantar region

Obturator (sciatic to
portion of ad. mag.).

Femoral (anterior
crural).

Sciatic.

Deep peroneal (anterior

tibial).
Superficial peroneal

(musculo-cutaneous) .

Tibial nerve.
Deep peroneal.
Medial and lateral plan-
tar.

CHAPTER VIII
THE ORGANS OF DIGESTION

MOUTH, PHARYNX, ESOPHAGUS, STOMACH, AND
INTESTINES

These, with the glands which secrete the digestive fluids, con-
stitute the digestive apparatus.

\Salivary Glatut

Esophagus

Vermiform Append,

FIG. 99. — GENERAL SCHEME OF THE DIGESTIVE TRACT, WITH THE CHIEF GLANDS
OPENING INTO IT; TOGETHER WITH THE LACTEALS ARISING FROM THE INTESTINE
AND JOINING THE THORACIC DUCT. — (Landois.)

The alimentary tract or canal is a series of channels included
within the organs named, constituting a long tube of mucous

130

DIGESTIVE FLUIDS, ENZYMES 131

membrane through which the food passes. The glands which
secrete the digestive fluids open into this tract.

The digestive fluid of the mouth is saliva.

The digestive fluid of the stomach is gastric juice.

The digestive fluids of the intestines are intestinal juice, and
pancreatic juice (assisted by bile).

Each of these fluids contains one or more of the peculiar sub-
stances called enzymes.

An enzyme is a ferment which by its presence causes certain
changes in other substances.

The enzymes of the digestive fluids cause the chemical changes
in food which are necessary for its digestion.

f Salivary, opening into the mouth.

I Peptic, " stomach.

The glands are { Intestinal, " " intestines.

I Pancreas, " " small intestine.

I Liver, " small intestine.

The tongue, teeth and glands are appendages of the alimentary canal.

THE MOUTH

The mouth, or oral cavity, is enclosed partly by muscles and
partly by bones. The muscles are the lip muscles in front, the
buccinator at the sides, and the mylo-hyoid in the floor. The bones
are the maxilla and the palate-bones above, and the mandible below.

The roof of the mouth is called the palate ; the bony portion is
the hard palate; the muscular portion attached to it is the soft
palate or the velum palati (veil of the palate). In the middle of the
soft palate is the uvula, which is a small projection downward.
All of these bones and muscles are in pairs, right and left.

Surgical note. — If, owing to lack of development they are not joined in
the middle line, cleft palate results. The cleft may be partial or complete,
and the divided upper lip is called harelip.

The oral cavity is lined with mucous membrane which is always
moist hi health. The part of the cavity between the lips and the
teeth is the vestibule.

The mouth contains the teeth and the tongue.

The teeth are already described.

The tongue lies in the floor of the mouth with its base curved
downward at the back and attached to the hyoid bone. It is
composed of muscles, and covered with mucous membrane which

132

ANATOMY AND PHYSIOLOGY

forms a special fold underneath the tip of the tongue connecting
it with the floor; this fold is called the frenum lingua. When the
frenum is short we say the tongue is "tied."

A little clip with the scissors is often sufficient to free it, but this is done
with care as an artery runs forward very near the frenum.

Septum
Nostril

Anterior naris

Hard palate

Anterior palatine

arch

Recess
Posterior palatine

arch

Tongue

FIG. 100. — THE ORAL CAVITY. — (Deaver.)

The dorsum, or superior surface of the tongue, is covered with
small projections called papilla, of three sizes — the vallate, the
largest, forming a V-shaped row at the back; the fungiform, next
in size, scattered over the surface but most numerous at the tip and
sides, and bright red in color; and the filiform, the smallest, cover-
ing the anterior two-thirds of the dorsum and borders (Fig, 101).

The tongue aids in mastication and swallowing, or deglutition.
It is also an important organ of speech and the principal organ of
taste.

THE MOUTH

133

Note. — The perception of bitter substances is plainer in the posterior
portion, while sweet, sour, and salty substances are more quickly recognized
in the anterior part and at the borders. The nerves of taste are in the papillae.

Some elevations of mucous membrane on either side of the base of the
tongue form the lingual tonsils. (These are seen only with the aid of the
laryngoscope.) They contain lymphoid tissue.

Parotid
gland

Floor of mouth and sub- ,

maxillary duct / \M\MY\ ^— . Hyoid bone

Submaxillary gland

(main portion is drawn backward)

FIG. 101. — SALIVARY GLANDS AND PAPILLA OF TONGUE. — (Morris.)

The mouth opens at the back into the pharynx, through the
passage called the isthmus of the fauces. This passage is bounded by
two folds on each side running downward from the soft palate and
called the palatine arches, or pillars of the fauces. Between the anter-
ior and posterior arch of either side is the palatine tonsil,1 a gland-
like body the use of which is not clearly understood2 (Fig. 100).

It presents small openings upon its surface leading into recesses or crypts
which are surrounded by the follicles of the tonsils.

Clinical note. — Follicular tonsillitis is an inflammation of the mucous
membrane and follicles in the crypts.

1 Feudal tonsil.

1 The student may see all of these structures by examining her own mouth with
the aid of a hand-mirror and a good light.

134 ANATOMY AND PHYSIOLOGY

Salivary glands. — The digestive fluid of the mouth is called
saliva. It is secreted by the salivary glands, three in number on
each side — the parotid, submaxillary, and sublingual (Fig. 101).

The parotid gland is situated in front of and below the ear,
and has a duct about two inches long (Stenson's duct} which runs
forward to open into the mouth opposite the second molar tooth
of the upper jaw, piercing the buccinator muscle. It secretes an
abundant watery fluid.

The surface line of Stenson's duct is drawn from the lobe of the ear to the
middle of the upper lip.

The submaxillary gland lies under the angle of the jaw, open-
ing into the floor of the mouth close to the f renum, by Wharton 's
duct. It secretes a thicker fluid than the parotid gland.

The sublingual gland lies in the (anterior) floor of the mouth
and opens under the tongue near the f renum, by several small
ducts. This.also secretes a thicker fluid.

The fluid which is constantly present in the mouth and com-
monly called saliva, is a mixture of the secretion of the salivary
glands and the mucous glands of the mouth.

The reaction of the saliva is alkaline. The enzymes of ferments
of saliva are ptyalin and maltase. The average daily quantity
of mixed saliva is 1400 gm.

THE PHARYNX

The pharynx, or throat, receives the food from the mouth. It
occupies a space in front of the spinal column from the base of the
skull to the fifth cervical vertebra, its rooj being formed by the
body of the sphenoid bone, joined to the occipital. The walls of the
pharynx consist of three pairs of muscles called the constrictors —
upper, middle, and lower, strengthened by a fibrous layer and
lined with mucous membrane.

The illustration shows that the constrictors are flat muscles attached at
the sides to the structures in front of the pharynx. Thus, from above down-
ward, their origin is on the pterygoid process, a special ligament, the mandible,
side of the tongue, hyoid bone, thyroid and cricoid cartilages. The fibers all
join a fibrous line, or raphe, at the back, which is suspended from the base
of the occipital bone. This is their insertion.

By due contraction of these muscles the food is grasped and
pressed downward into the esophagus. They are composed of
striated or voluntary muscle fibers.

OPENINGS OF PHARYNX

135

. The upper part of the pharynx is behind the nose and is called the
nasal part, ornaso-pharynx. The middle part is behind the mouth
and is called the oral part, or oro-pharynx. (It is this part which we
see when looking directly into the throat.) The lower part is behind
the larynx and is called the laryngeal part, or the laryngo-pharynx.
The openings oj the pharynx are seven in number: the two
choana (posterior nares) communicating with the nose; the two

Orbic. oris muscle
Special ligament

Mylo-hyoid muscle

Hyoid bone

Thyro-hyoid

membrane

Thyroid cartilage

Cricoid cartilage
Trachea

Esophagus

FIG. 102. — THE PHARYNX. — (Holden.)

auditory (Eustachian) tubes communicating with the ears, and the
isthmus of the fauces, communicating with the mouth. Beiow, it
communicates with the larynx (the opening being guarded by the
epiglottis) and opens into the esophagus.

The food passes through the oro-pharynx and laryngo-pharynx,
the naso-pharynx being an air-passage.

In the roof of the pharynx is a small mass of lymphoid tissue called the
pharyngeal tonsil. If hypertrophied it forms an adenoid tumor or "adenoid"

THE ESOPHAGUS

The esophagus (Figs. 102, 99) begins at the lower end of the
pharynx and extends downward in the neck in front of the spinal

136

ANATOMY AND PHYSIOLOGY

column, to pass into the thorax. It finally comes forward in
front of the aorta, passes through the diaphragm, and terminates
in the stomach. It is a tube about nine inches long, having two
layers of muscles (circular within, longitudinal without) and lined

jj

FIG. 103. — SHOWING SITUATION OF PHARYNX BEHIND NOSE, MOUTH, AND LARYNX

— (From Denver's "Surgical Anatomy.")

a, b, c, d, e, Turbinal bones and meatuses of the nose; g.i, tongue; h, posterior
'palatine arch; y, anterior palatine arch; k, hyoid bone;/, mylo-hyoid muscle (floor of
mouth); m, thyro-hyoid membrane; «, ventricle of larynx; p, q. r, sphenoid bone and
sphenoidal sinus; v, hard palate; w, soft palate; x, uvula; z, tonsil; /, naso-pharynx; «,
orifice of auditory tube; aa, oro-pharynx; dd, laryngo-pharynx; bb, epiglottis; ee,
upper portion of larynx; gg, vocal bands; if, false vocal bands; hh, lower part of
larynx: it, cricoid cartilage ;jj, trachea.

with mucous membrane. By contraction of the different muscles
from above downward the food is passed along to the stomach.

The esophagus lies at first immediately behind the trachea.
The upper part is composed of striated, or voluntary muscle like
that of the pharynx; in the lower part the muscle is non-striated,
or involuntary, like the stomach.

THE STOMACH 137

At the termination in the stomach, the circular fibers are most
numerous, forming the cardiac sphincter which prevents the return
of stomach contents.

The remaining organs of digestion are contained in the ab-
dominal cavity, which is lined with a serous sac or membrane
called peritoneum (see p. 367). These organs are developed from
an original straight tube behind the peritoneum. Therefore,
as they grow, they press forward against it and get a covering
which is called their serous layer. Their muscular coats are all
involuntary or unstriped muscle.

THE STOMACH

The stomach (gaster, Fig. 104) is in the epigastric region of the
abdomen just below the diaphragm. Shape and size: like a
curved flask, ten to twelve inches long and six to eight wide at
the larger end, which is turned toward the left side. Average
capacity: five pints in distention ; two pints when moderately filled.

The stomach has two surfaces, two borders, two orifices and two
extremities — cardiac and pyloric, with a pre-pyloric part between
them.

The surfaces are the anterior — looking slightly upward; and the
posterior — looking slightly downward.

The borders are usually called curvatures; the upper border is
the lesser curvature (about five inches in length) ; the lower border is
the greater curvature (about twenty inches in length).

The left extremity is the expanded portion called the tundus of
the stomach (also the greater cul-de-sac), and the cardiac end (from
its nearness to the heart).

The right extremity is called the pyloric extremity. It is just
below the liver.

The orifices are at the extremities. At the left is the esopha-
geal orifice, guarded by the sphincter of the cardia; at the right
is the pyloric orifice, guarded by the sphincter of the pylorus or
"gate-keeper."

The coats or tunics of the stomach are four in number —
mucous, submucous, muscular, and serous.

The mucous layer, or mucosa, is the innermost layer. It is
pink in color but becomes bright red when food is present, from the
increased blood-supply necessary for digestion. It lies in folds, or

ANATOMY AND PHYSIOLOGY

rugae, running from one extremity to the other — the longitudinal
folds. This layer contains the gastric glands which secrete the
gastric juice and pour it through their ducts into the stomach:

The submucous layer or submucosa is a network of connective
tissue next to the mucous coat. It bears fine vessels, nerves and
lymphatics, and connects the mucous and muscular tunics together
loosely, so that when the stomach is distended the longitudinal folds
simply disappear, without injury to the mucous membrane.

The muscular coat (or tunic} comprises three layers of non-
striated muscle: internal, middle and external. The internal layer

Celiac artery
Gastric artery

Artery
to duo-
denum
Head of
pancreas

\

FIG. 104. — THE STOMACH AND SPLEEN. — (Morris.}

consists of oblique fibers (it is a thin layer and is mostly con-
fined to the cardiac portion). The middle layer is a complete
layer of circular fibers. They are most numerous at the ex-
tremities of the stomach, where they form two ring-shaped
bundles. One is the sphincter of the cardia, surrounding the lower
end of the esophagus and the cardiac orifice of the stomach; the
other is the sphincter of the pylorus, which is a strong ring-muscle
diminishing the size of the pyloric orifice so that it is the narrowest
portion of the alimentary tract (a half -inch, or 3 mm.). The ex-
ternal layer consists of longitudinal fibers (fibers running length-

THE INTESTINE

139

wise) which are continued from the similar layer of the esophagus,
and pass on to those of the intestine.

The serous coat (or tunic) is a portion of the great serous mem-
brane of the abdomen, called the peritoneum (page 367). The
two surfaces of the stomach are covered by different layers of per-
itoneum which will be described elsewhere (Fig. in and p. 148).

The gastric glands are embedded
in the mucosa. They are tubular in
form, microscopic in size, and very
numerous (their number is estimated
at 5,000,000). They differ markedly
in the two portions of the stomach.
The cardiac glands secrete the diges-
tive ferments, pepsin and rennin,
while the pyloric glands secrete mucus
also (Fig. 105).

The 'reaction of the gastric juice is
acid (owing to hydrochloric acid).
This acid is a natural but not a
powerful antiseptic.

The position of the stomach is
oblique, the pyloric end being on a
lower level than the cardiac. It is also the movable end.

The location of the stomach is mostly in the epigastric region
(Fig. 235). It is below the portion of the diaphragm which
supports the heart; behind it are the largest artery and vein in the
body — the aorta and the inferior vena cava. The pyloric end ex-
tends under the liver in the right hypochondrium, while the cardiac
end is in contact with the spleen in the left hypochondrium.

Clinical notes. — When the stomach is empty it tends to a vertical position
when filled, it swings upward and forward to become again oblique. If
much distended, as with gas, it embarrasses the action of the heart by pressure.

The infant's stomach is nearly or quite vertical and easily overflows; its
capacity at birth is one ounce, reaching two ounces at about the end of a
fortnight and eight ounces at ten or eleven months.

THE INTESTINE

The intestine or bowel begins at the pyloric orifice of the
stomach and continues to the end of the alimentary tract. It is
from twenty-five to thirty feet in length (Fig. 106).

FIG. 105. — SECTION OF PYLORIC
GLANDS FROM HUMAN STOMACH.
a. Mouth of gland leading
into long, wide duct (6), into
which open the terminal divi-
sions, c. Connective tissue of
the mucosa. — (After Pier sol.) •

140

ANATOMY AND PHYSIOLOGY

Like the stomach, it is composed of four coats or tunics —
mucous, submucous, muscular and serous.

The mucous coat is the glandular coat; that is, the glands which
secrete intestinal juice are imbedded in the mucous coat, and their
ducts open on its surface.

Vessels
of large •

intestine |

Cecum

Appendix

FIG. 106. — THE INTESTINES. — (Morris.)
Large intestine thrown upward, small intestine drawn to left.

In addition, small gland-like bodies of lymphoid structure are scattered
throughout this coat. They have no ducts. They are probably lymph
nodules — the so-called solitary glands.

The submucous coat bears the fine vessels and nerves which
supply the mucous coat. It connects the mucous and muscular
coats together.

THE SMALL INTESTINE' 141

The muscular coat comprises two layers (like the esophagus),
an inner layer of circular fibers, an outer one of longitudinal
fibers.

The intestine is divided into the following parts:

Duodenum ( Cecum

Ascending

Small intestine { Jejunum Large intestine \ Colon { Transverse

[ Descending
Ileum ( Rectum

The Small Intestine

. The small intestine is about twenty feet in length, and about
two inches wide in its upper (widest) part. It extends from the
stomach to the colon, beginning with the pyloric sphincter in the
right hypochondrium and ending with the ileo-colic sphincter in
the right iliac region.

The mucous coat of the small intestine forms circular folds
(old name, valvulae conniventes) which are permanent, that is,
they never disappear however widely the bowel may be distended.
They serve to increase the area of mucous membrane for purposes
of digestion and absorption (Fig. 108). This layer contains the
intestinal glands.

The entire mucous coat is covered with tiny projections hair-
like in size (from 1/2 to i mm. long) called villi, which give it a
velvety appearance (Fig. 107).

The villi are absorbing structures or absorbents. (They may
be demonstrated in a good light by laying a piece of intestinal wall
in a shallow tray of dear water; the water will float their free
extremities.)

In the midst of each villus is a minute lymph capillary, surrounded by a
fine network of blood-vessels and lymph spaces, the whole covered by a layer
of the special epithelium of the intestine. Lymph vessels of villi are called
lacteals because during digestion they contain a milky-looking fluid.

The muscular coat is in two layers — circular within, longitudinal
without — pretty evenly distributed.

The serous coat covers all except a portion of the first division
(see duodenum) .

The duodenum is the first division of the small intestine

142

ANATOMY AND PHYSIOLOGY

(Fig. 109). It begins at the pyloric end of the stomach and
is about ten inches long; curves upward, backward, to the right
and downward, and then continues across to the left side of the

spinal column.

About four inches from the
pylorus the mucosa presents an
elevation — the bile papilla,
where the common bile and
pancreatic duct opens.

The circular folds of the
mucous coat begin in the lower
portion and are unusually large.

FIG. 108. — CIRCULAR FOLD OR VAL-
VXJLS CONNIVENTES. — (Brinton.)

FIG. 107. — SECTION OF INJECTED SMALL

INTESTINE OF CAT.

a, 6. Mucosa. g. Villi. «. Their absorbent
vessels, h. Simple follicles, c. Muscularis
mucpsae. j. Submucosa. g.6. Circular and
longitudinal layers of muscle. /. Fibrous
coat. All the dark lines represent blood-
vessels filled with the injection mass.
— (Piersolt) i

Note. — The inferior part of the duodenum is behind the peritoneum, this
part has no serous coat.

The jejunum is the second division of the small intestine —
so named because it is found empty. It possesses all of the char-
acteristic structures: villi, circular folds, intestinal and solitary
glands. It lies in the umbilical and the two lumbar regions.

The ileum is the third division of the small intestine — so
named because of its frequent twisting. There is no definite

THE ILEUM 143

separation between the end of the jejunum and the beginning of
the ileum.

The villi and circular folds are all found throughout the ileum.

The ileum ends in the right iliac region by opening into the
large intestine. This orifice is doubly guarded; first, by two folds
of mucous membrane strengthened by fibrous tissue, called the
ileo-cecal valve; second, by a circular muscle called the ileo-colic
sphincter; this is the more important of the two.

FIG. 109. — LIVER, PANCREAS, DUODENUM, SPLEEN AND KIDNEYS, i, 2, 3.
Duodenum. 4, 4, 5, 6, 7, 7, 8. Pancreas and pancreatic ducts. 9, 10, n, 12, 13.
Liver. 14. Gall bladder. 15. Hepatic duct. 16. Cystic duct. 17. Common
duct. 18. Portal vein. 19. Branch from the celiac axis. 20. Hepatic artery. 21.
Coronary artery of the stomach. 22. Cardiac portion of the stomach. 23. Splenic
artery. 24. Spleen. 25. Left kidney. 26. Right kidney. Section of pancreas
to show ducts. Liver turned upward and stomach removed to show duodenum.
— (Sappey.)

The secreting glands of the small intestine are embedded in the
mucosa, and are found in every part. They are called the in-
testinal glands or intestinal follicles, or glands o] Lieberkuhn.
They are tubular in shape, and secrete the greater portion of
the so-called intestinal juice. The ferments of the glands are erep-
sin, invertase, maltase, etc. The reaction oj the fluids is alkaline.

In addition to the above, there are small round bodies called
solitary glands. They increase in size in the lower end of the
ileum where they are grouped in oblong patches — the Peyer's

144 ANATOMY AND PHYSIOLOGY

patches (or agminated glands) the largest of which may measure
three inches in length.

Clinical note. — The solitary glands (more especially the Peyer's
patches) become inflamed and ulcerated in typhoid fever.

The Large Intestine

The large intestine is about five feet long and two and one-half
inches wide in the widest part. It begins where the small intestine
ends (in the right iliac region), ascends through the right lumbar,
crosses the abdomen in front of the small intestine, descends to
the left iliac region, and thence down through the pelvis, ending in
front of the coccyx. (See Regions of the Abdomen, p. 366.)

The mucous coat is smooth and rather pale. No folds are
present; and no villi, but the solitary and tubular glands are
numerous, like those of the small intestine.

The circular fibers of the muscular coat are evenly distributed,
but the longitudinal fibers of the cecum and colon are arranged in
three bands, placed at even distances apart. These bands are
shorter than the tube itself, therefore they gather it into puffs
which give the bowel a sacculated appearance. By this, the large
bowel may be recognized at once, even should it be really small
in actual size in some portion of its extent.

The serous coat covers the greater part of the large intestine;
the exceptions will be noted later. (See p. 146, Surgical Note,
The Rectum?)

The four divisions of the large intestine are the cecum, the
colon, the sigmoid loop, and the rectum (Figs. 106, no).

The cecum, or first division, is a short pouch hanging below the
level of the ileocolic valve and presenting the opening of the appen-
dix vermiformis or appendix ceci. The three longitudinal bands
of the muscular coat meet at the base of the appendix, which is a
small tube three or four inches long, attached to the posterior wall
of the cecum. It often turns upward, quite as often downward,
and may lie transversely. It has all four coats, with intestinal
and solitary glands, but is of no use.

Clinical note. — Owing to its small size any substance which enters the
appendix is apt to be retained, and if it is of an injurious character it will
cause appendicitis. This disease is more often caused by the action of

THE COLON

145

harmful bacteria than the celebrated cherry-stone. Small intestinal worms
have been found within the appendix.

The ilio-cecal valve consists of two folds of mucous membrane
with muscle fibers between the layers. They are placed at the end

FIG. no. — THE LARGE INTESTINE.

The small intestine and its vessels are drawn to the right to show the sigmoid colon
and the rectum. The transverse colon is thrown upward. — (Morris.)

of the ilium where it opens into the colon, and project toward each
other, leaving only a slit-like passage.

The colon begins at the ilio-cecal valve. The first part, or
ascending colon, passes upward in the right lumbar region. After
making a bend under the liver— the right colic flexure (or hepatic
flexure), it becomes the transverse colon, which hangs in a loop across
the abdomen in front of the small intestine. Another bend occurs
under the spleen, the left colic flexure (or splenic flexure) ; thence
the descending colon passes downward in the left lumbar region to
the left iliac fossa. Here it makes an S-shaped or sigmoid bend

146 ANATOMY AND PHYSIOLOGY

and becomes the so-called sigmoid colon. It then enters the pelvis
to become the rectum.

Surgical note. — The ascending colon lies so close to the posterior abdominal
wall that there is no peritoneum behind it, and the descending colon also is bare
in a narrow strip at the back, consequently the surgeon may take advantage of
this condition to open the colon without wounding the peritoneum, in the
operation called lumbo-colotomy.

The rectum is about five to seven inches long, very distensible,
and so called because it has no convolutions, but simply follows the
curve of the pelvic wall, lying in front of the sacrum and coccyx.
In the last inch or inch and a half it bends backward (perineal
flexure) to pass the tip of the coccyx. This is the anal canal, and
it ends at the opening called the anus (Fig. no).

The portion above the anal canal is the widest part — the rectal
pouch. .

The mucous membrane of the rectum is red, and usually pre-
sents two or three special folds about two or three inches above the
anus, called the rectal folds, or Houston's valves.

The largest, a permanent fold, is on the right side about two and one-half
inches above the anus and called the third sphincter. Two smaller ones, not
permanent, are on the left side, above and below the former.

The muscular coat has the two layers, circular and longitudinal.
The peritoneal coat covers the front and sides of the upper part only.

The reaction of the fluids in the large intestine is alkaline.

Sphincters of the anus. — The circular fibers around the anal
canal form the internal sphincter.

The external sphincter is a flat circular muscle just under the
skin around the anus. (Its contraction causes the radiating lines
in the skin.) The function of the sphincters is to guard and
control the anus.

Clinical note. — The point of a syringe should be passed in an upward and
forward direction through the anal canal, and then turned backward.

RJESUMJS.

The alimentary tract begins with the mouth and ends with the large in-
testine, passing through the head, neck, thorax, and pelvis. It is practically
a long tube of mucous membrane surrounded by layers of muscle and held to
them by connective tissue. The mucous membrane contains glands which
secrete the digestive fluids. The muscle layers pass the food along, that it may
be acted upon in all portions of the tract; and wherever free motion accom-

THE MESENTERY

147

panics the digestion of the food, a serous layer is added outside of all to prevent
friction.

The digestive fluid of the stomach is acid; in all other parts it is alkaline,

Peristalsis is the name given to the peculiar motion of the
stomach and intestine during the passage of their contents. The
circular fibers compress the food and at the same time the longi-
tudinal fibers shorten the tube. This action goes on from above
downward, causing a sort of worm-like movement which is de-
scribed as peristalsis, or peristaltic movement.

Epiploic foramen
Pancreas .

Duodenum

Transverse meso-colon
Aorta

Rectum

Li

Gestrohepatic omentum

Stomach —

Transverse colon

Mesentery

Small intestine

Uterus

Bladder

FIG. in — DIAGRAM OF A SAGITTAL SECTION OP THE TRUNK, SHOWING THE RELA-
TIONS OP THE PERITONEUM. — (Allen Thompson.)

The mesentery is the fold of peritoneum which holds the
jejunum and ileum in place. This fold leaves the posterior ab-
dominal wall at a line inclining downward to the right, about five
or six inches long; but it includes twenty feet of intestine, and
therefore it is like a very full ruffle twenty feet in length with a
band of six inches. The vessels and nerves of the intestine lie
between the layers of the mesenteric fold.

Any fold of peritoneum which connects a portion of intestine to the wall of
the trunk is a mesentery. The meso-colon connects the colon with the abdom-

148 ANATOMY AND PHYSIOLOGY

inal wall; the meso-rectum connects the rectum with the pelvic wall; the
large mesentery holds the ileum and jejunum to the posterior abdominal wall.

An omentum is a fold of peritoneum connected with the stomach. The
greater omentum hangs from the greater curvature; the lesser omentum connects
the lesser curvature with the liver (being called the gastrohepatic omentum) ;
and the gastrosplenic omentum connects the stomach and spleen. (Two
layers of peritoneum pass from the under surface of the liver to the lesser
curvature of the stomach, forming the lesser omentum. They then separate
to enclose the surfaces of the stomach, making its serous coat. They come
together again at the greater curvature and hang down in the shape of a large
serous sac with double walls, the greater omentum, which hangs in front of the
small intestine.)

Note. — The transverse meso-colon usually becomes adherent to the greater
omentum (Fig. 112).

THE PANCREAS

The pancreas (Figs. 109, no) is a racemose gland, behind and
below the stomach. It is about seven inches long and somewhat
resembles a hammer in shape, the head being turned to the right
and lying within the curve of the duodenum, the body crossing to
the left, and the tail reaching the spleen. It consists of lobules,
each with its duct; these unite to form the pancreatic duct which
conveys the pancreatic fluid to the duodenum. The duct opens
(with the common bile duct) into the duodenum about four inches
from the pylorus (guarded by a valve).

The three pancreatic ferments are amylopsin, trypsin and
steapsin (ior'starch, proteid and fat) (see page 161).

THE LIVER

The liver (Fig. 112) is the largest abdominal organ, and the
largest gland in the body. Its normal weight is between three
and four pounds (1300 to 1700 grams). It is underneath the dia-
phragm, in the right upper portion of the abdomen, the thin left
lobe extending across the epigastric region above the stomach.
Its general shape is that of a wedge, much thicker at the right side
than the left, and with the thin edge turned forward. The upper
surface is convex, and marked off by a ligament into two lobes,
right and left. The lower surface is divided by five fissures into
five lobes. The largest fissure is the transverse, the porta (or gate)
for the passage of vessels,1 nerves and ducts.

1 Lymph vessels and hepatic artery. Hepatic veins take a different route.

THE LIVER

149

The substance of the interior of the liver is composed of hepatic
cells, grouped in lobules, with a multitude of blood-vessels, lym-
phatics and nerves, supported by connective tissue.

FIG. 112. — THE ABDOMINAL ORGANS. — (Gerrish, ajter Testut.)
The liver is turned upward to show the inferior surface with the gall-bladder.
The vessels entering and leaving the porta are also seen, the lesser omentum having
been removed.

An hepatic lobule measures only about a millimeter (^V of an inch) in
width. Between its cells there is a fine network of hepatic and portal blood-
vessels, and lymph spaces; also bile passages. The blood-vessels empty into
hepatic veins; the lymph spaces form lymph vessels, and the bile passages
lead to small bile ducts which unite and reunite to form the hepatic ducts.

150 ANATOMY AND PHYSIOLOGY

Five ligaments of the liver hold it in place attaching it to the
diaphragm and abdominal wall — the round, the broad, the coronary,
and two lateral.

The round ligament is a cord (the remains of the umbilical vein)
inclosed in the broad, which, with the lateral and coronary, is of
peritoneum. It is the broad ligament which connects the superior
surface of the liver with the diaphragm and is therefore called the
suspensory ligament. It also marks off the right from the left
lobe on that surface. The principal support of the liver is by
its connection with the diaphragm.

The liver secretes a yellow alkaline fluid called bile which is
conveyed through the porta by two ducts, the right hepatic and
left hepatic; these unite to form one, the hepatic duct proper,
which is soon joined by the cystic duct from the gall-bladder.

The -gall-bladder occupies a fissure on the inferior surface of
the liver. It is a pear-shaped sac three or four inches long, of
fibrous tissue and muscle fibers lined with mucous membrane and
partially covered with peritoneum. It contains a variable quan-
tity of bile (or "gall") in reserve. The .only opening of the
gall-bladder is for the cystic duct, which joins the hepatic to form
the common bile-duct, or ductus communis choledochus (Figs.
109, 112).

Bile, as it flows from the gall-bladder, is a thick or viscid
yellow fluid having sometimes a brown tinge, or it may be greenish.
It is formed as a thin fluid in the cells of the hepatic lobules,
from materials brought in the portal vein (which enters the liver
at the porta). (See page 148.)

Its characteristic elements are bile salts, bile pigment, and
cholesterol — a substance which is soluble only in normal bile.
Any of these may be found in gall-stones; this is especially true
of cholesterol.

Bile is discharged from the liver by the right and left hepatic
ducts, thence into the hepatic duct proper, and the common bile
duct or ductus communis choledochus, as already stated.

Note. — The production of bile is continuous; its flow into the
intestine is intermittent. It appears in the duodenum only during
the process of digestion; in the interval it is stored in the gall-
bladder.

Notes. — The cystic duct is about i 1/2 inches long; the hepatic

THE SPLEEN 151

duct, 2 inches long; the common duct, 3 inches long. Just before
it opens into the duodenum, the common duct expands into a
little pouch called the ampulla of Vater. A gall stone may lodge
in this place.

Clinical notes. — The liver is pressed downward by the movement (con-
traction) of the diaphragm in inspiration, and can then be felt below the
costal arch in front. During expiration it slips upward with the rise of the
diaphragm.

Gall stones may form in the gall-bladder or in any of the ducts. If in the
gall-bladder they may exist for a long time without causing symptoms, the
bile flowing into the intestine without obstruction; if in the cystic duct the
symptoms are also deferred, but if in either the hepatic duct or the ductus
communis, obstruction to the outflow promptly causes jaundice and other
disorders, with distention of the gall-bladder. Inflammation of the gall-
bladder is Cholecystitis, of the liver — hepatitis.

The viscidity of the bile is increased in inflammation of the gall-bladder
and often dogs the ducts to the point of obstruction, as in jaundice.

THE SPLEEN

Although there are reasons for including the spleen in the list of duct-
less glands it is decided to include the description of this organ in the
present connection. It is a very important organ with a remarkably free
blood supply, which suggests great activity for some purpose or purposes,
and the only direct connection of the spleen with any other . organ is by
blood-vessels with the liver, but the significance of this is a matter of con-
jecture at the present time.

The spleen (or lien) is situated at the left of the stomach,
directly beneath the diaphragm by which it is entirely covered. It
is oval in shape, convex on the lateral -surface and concave on the
medial, where a depression called the hilus is seen for the passage of
vessels and nerves (Fig. 109).

The fibromuscular capsule which forms the surface of the spleen sends
numerous septa into the interior, and within the spaces of the network thus
formed the splenic pulp is contained. This consists of blood which has
escaped from the open terminals of numberless capillaries, of lymphoid cells
and broken down red cells, coloring matter and particles of waste. Small col-
lections of lymphoid cells around the capillaries may be seen upon section
of the organ; they are the Malpighian bodies of the spleen; their function is
obscure.

The splenic artery is the largest branch of the celiac axis and
the consequent large blood supply gives a dark red color to the

152 ANATOMY AND PHYSIOLOGY

spleen. The peritoneal covering completely surrounds it, except
to allow vessels and nerves to pass through the hilus.

The function of the spleen is not well understood, as both
animals and human beings have been known to live in health after
its removal, but its structure and the study of the blood of the
splenic artery and splenic vein reveal the folio whig facts:

The spleen pulp contains a vast number of white cells (chiefly
lymphocytes) and many disintegrating red cells. It has a high
percentage of iron, especially after chronic diseases. The blood in
the vein which leaves it contains many more white cells than that
in the artery which enters; also — many small red cells are present,
some of which are still nucleated (newly formed). Two enzymes
are found — one a uric-acid-forming enzyme.

From these observations the conclusions suggested are that the
spleen gives birth to leucocytes; that it stores and works over the
iron from broken-down tissues (including red cells) ; that it may
assist to form red cells and that it forms uric acid from broken-
down protein substances.

Clinical notes. — The elasticity of the capsule allows frequent variations
in size, which in health are normal; it is always larger during digestion and
smaller in fasting. In certain diseased conditions it is much increased in
size, as in malaria; and notably in leukemia, which is characterized by an
enormous increase in the number of white cells in the blood, as well as in the
size of the organ itself. The significance of these variations in size is not yet
explained.

CHAPTER IX

PHYSIOLOGY OF THE DIGESTIVE ORGANS
FOODS, DIGESTION, ABSORPTION

FOODS

The human body is a machine constantly in motion; therefore,
its cells continually use up their force, and continually need renew-
ing. The material for this renewal is supplied by the food which
we eat. Substances classed as foods must be able to "repair waste
and provide the raw materials for growth. All substances which
have this power are foods. . . . Thus, water salts and oxygen
are true foods" (Mathews). As the various parts of the body
are composed of quite different tissues, so the food is of a mixed
character.

The composition of the tissues includes four classes of food
principles, as follows:

1. Proteins. }

2. Carbohydrates (sugars and starches). [ organic.

3. Fats. J

4. Mineral salts including water. inorganic.
In the body : —

1 . Proteins are found in all tissues, but most abundantly in —
blood, as serum-albumin, fibrinogen, hemoglobin; lymph, as serum-
albumin; muscles, as myosinogin; milk, as caseinogen.

2. Carbohydrates (sugars and starches) are found principally
in — blood, as dextrose; liver and muscles, as glycogen;1 milk as
lactose.

3. Fats are found principally in — milk, as an emulsion; nerves,
lymph, blood cells; bones, as marrow; subcutaneous fascia and
adipose tissue around organs.

4. Mineral salts are found in all tissues and fluids of the body;

1 Glycogen is an animal starch formed within the body, the others are sugars.
Dextrose, grape sugar and glucose have the same composition.

153

154 ANATOMY AND PHYSIOLOGY

in — bones and teeth especially, as lime salts; muscles, nerves, and
blood, as potassium salts; all tissues, as sodium salts; red blood cells,
as iron.

In the food : —

1. Proteins exist in — meats, as myosin and albumin; eggs, as
albumin in the white, lecithin in the yolk; grains, as gluten;
vegetables: peas, beans, corn, etc., as vegetable albumin.

2. Carbohydrates (sugars and starches) exist in — fruits, as
dextrose and levulose; milk, as lactose; sugar cane, beets, etc., as
cane sugar and saccharose; vegetables: peas, beans, potatoes, etc.,
as starch.

3. Fats exist in — milk, as an emulsion; corn, oats and other
grains; eggs (the yolk) and all animal foods in varying quantities.

4. Mineral salts exist in — all foods (but must be added in bulk) ;
water, the most important; vegetable, grains and protein foods, as
phosphate of calcium; meats and all animal food, as iron; all foods,
as sodium chloride or common salt.

Proteins must be supplied to all tissues; they are the tissue
builders.

Carbohydrates (or sugars and starches) are utilized by liver
and muscle, and are sources of heat and muscle energy.

Fats are needed for the marrow of bones, as protective cover-
ings, and to fill in spaces between organs; also to preserve body
heat as well as to produce it.

Mineral salts are necessary to life.

Water constitutes nearly three-fourths of the body weight,
and is universally present, even in the hardest tissues, as the
enamel of teeth. Its most important uses are: i. To hold in
solution the nutritive principles of the food, that they may be
absorbed. 2. To sweep away waste matters to organs which
can secrete them. 3. To aid in regulating the temperature of
the body.

Sodium chloride stands next in importance to water. It is
necessary to the normal activities of the tissues. It contributes
to the formation of hydrochloric acid for gastric juice.

Phosphate of calcium is needed by bones and teeth; it is the
most abundant salt in the body, next to water.

Calcium is indispensable to normal blood.

Iron is a necessary element of red blood cells, in hemoglobin.

FOODS 155

Elements of Organic Food. — Sugar, starch and fat consist of
carbon, hydrogen and oxygen (CHO). The proteins add nitrogen
(CHNO) and a little sulphur (CHNOS). (The formulae are omit-
ted, the symbols being sufficient for our purpose.) These ele-
ments are all furnished in suitable quantities by the food as
described, except oxygen. This is obtained in great measure
from the air we breathe which consists of nitrogen and oxygen.
Nitrogen simply dilutes the oxygen, being itself inactive in this
combination.

In accordance with the definition of food given at the beginning
of this chapter, we regard atmospheric air as an important source
of food, since it provides the essential element oxygen, which
constitutes about one fifth of the bulk of the air we breathe (see
page 231). It passes from the lungs into the blood and is carried
by the red cells to the tissues at large.

With the exception of oxygen (which is introduced through
the lungs), food enters the system through the alimentary
tract, being here prepared for the uses for which it is designed,
by the process of digestion.

Different articles of food should be combined in such ways as
to secure proper adjustment of food principles to body needs.

For example: with meats, vegetables should be served rather
than milk or eggs.

Avoid a number of starchy vegetables in the same meal. For
example: to potatoes, or rice, or hominy, add green vegetables, as
string-beans, spinach, celery, etc.

There is good reason for adding butter to bread and oil to salad,
as neither flour nor green things contain fat.

Milk is well combined with starchy food, having within itself
both proteins and fat. Eggs can take the place of meat to a large
extent; they may be combined with milk.

The shell or husk of grain contains certain mineral salts which
are about our only source of silica for the hair and teeth; therefore
— give whole grains to growing children.

Whole-wheat flour, and ripe beans or peas, contain protein in a
vegetable form; ripe corn (cornmeal) contains more fat than other
cereals, and protein as well.

All vegetables contain a varying amount of fiber which is
indigestible, but which is beneficial, since it serves to prevent the

156 ANATOMY AND PHYSIOLOGY

concentration of waste matters in too small bulk for the action of
the large intestine. Three reasons for cooking food are as follows :

Cooked starch is more easily digested than raw, for the following
reasons: The change of starch into sugar requires that it should
first be hydrated, that is, combined with water. It exists in gran-
ules and each granule of starch has a covering of cellulose which is,
in saliva, indigestible. In the process of cooking, the boiling
water penetrates to the granule, uniting with it and causing it to
free itself from the envelope. At once it can be acted upon by
ptyalin if in the mouth, or amylopsin if in the small intestine.
With raw starch, hydration goes on slowly or not at all. Imper-
fectly cooked starch is unwholesome for the same reason.

Vegetables also should be thoroughly cooked both on account
of the starch which they contain, and the fibrous material, which
needs partial disintegration by heat.

Meats are more easily digested if cooked long enough to soften
their connective tissue fibers. By heat these are converted into
a gelatinous substance which can be disposed of by pepsin and
trypsin.

Another advantage secured by the cooking of food, lies in the
effect of the flavors thus developed, by means of which appetite
is encouraged and the secretion of digestive fluids is stimulated.

Clinical note. — The "scraped beef sandwich," so of ten ordered for patients,
contains the substance of the muscle cell alone, which has been scraped away
from the connective tissue fiber; it is easily digestible because it may at once
be converted into peptone without the necessity for first digesting the tougher
covering.

DIGESTION

Digestion is the process of so changing the food in the
alimentary canal that its nutritive parts may be absorbed into the
system.

The organs described in Chapter VIII are so connected and
arranged that they receive and act in consecutive order upon the
food, causing a series of changes which result in separating nutri-
ment from waste and preparing it for absorption, expelling the waste
from the system.

The process of digestion begins in the mouth and continues
throughout the small intestine. The food is first divided into

DIGESTION 157

small pieces by means of the teeth. This is mastication. At the
same time it is mixed with saliva; this is hydration and insalivation.

By the act of swallowing, the softened mass is passed into the
pharynx and down through the esophagus to the stomach. This
is deglutition. (The soft palate prevents it from going upward to
the nose, and the epiglottis prevents it from entering the larynx.)

The stomach now takes charge. The mass is compressed and
moved about by the layers of the muscular coat until it is thor-
oughly saturated with gastric juice, and becomes a pale yellowish
fluid called chyme. As fast as this is accomplished, the pylorus,
or gate-keeper, allows it to go through into the duodenum, where
it meets the intestinal and pancreatic juices, and bile.

Continuing through the small intestine it loses in increasing
measure its fluid and nutritious portions, and in the large intes-
tine it is still further reduced to waste alone, which is expelled
from the body.

Mechanical Processes of Digestion

The passage of food through the several organs, as above
outlined, represents the sum of the mechanical processes resulting
from the peristaltic action of the muscles of the tract, which are al-
ready described as consisting of layers of circular and longitudinal
fibers surrounding the tube of mucous membrane. In addition
to these, there is an entirely different set — the muscles of masti-
cation, which move the mandible or lower jaw, and keep the food
between the upper and lower teeth. Their action constitutes
the first mechanical process of digestion; this is of great importance,
because only when the food is in small fragments (or masticated]
can the digestive juices have access to the whole mass.

Chemical Processes of Digestion

The first occurrence which follows the introduction of food is
an increased flow of blood to the part and activity of the secreting
cells as the food arrives, beginning with the secretion of saliva.
In fact, the cells may begin to work beforehand, being stimulated
by the thought of food. This is true of both saliva and gastric
juice.

The chemical process of digestion is brought about by
the action of digestive fluids in the mouth, stomach and

158 ANATOMY AND PHYSIOLOGY

intestines — or saliva, gastric juice, and intestinal fluids; it is
greatly facilitated by the presence of enzymes in the fluids. En-
zymes are organic substances which are the result of cell ac-
tivity. Their composition is undetermined; we know them
only by their works. The characteristic which makes them valu-
able is their power to stimulate rapid changes in certain other
substances by their presence alone, while they themselves remain
unchanged. In this way, the smallest quantity of an enzyme
may effect changes in a large amount of material. (See p. 165.)

In the mouth the mechanical process includes mastication and
insalivation. By the teeth the food is divided, then crushed and
ground; at the same time it is softened by saliva. The parotid
saliva does most of this, being the most abundant; it is poured
into the mouth just outside the upper second molar and thus it
mixes at once with the mass as it is crushed and ground. Sub-
maxillary and sublingual saliva contain much more mucin and
lubricate as well as soften the food. The saliva also dissolves
the sapid substances, in order that the nerves of taste in the tongue
may appreciate them. One can neither taste nor swallow a per-
fectly dry substance.

In the mouth the chemical process is the conversion of starch
into sugar. The digestive fluid is saliva; the two enzymes are
ptyalin (salivary diastase} and maltase. Ptyalin does most of the
work — changing the starch molecule first into dextrin and then
into maltose (and a little dextrose). Not all the starch taken at
one time is digested in the mouth for the reason that it leaves
the mouth too soon. (If it is retained in the mouth for some
time, especially if mastication be continued, the presence of the
sugar thus formed will be evident to the taste.)

The digestion of starch requires an alkaline medium; ptyalin
cannot act in acid fluids.

Saliva is alkaline.

Being masticated, insalivated and hydrolyzed (see p. 166), the
food is now prepared for deglutition or swallowing, by which it is
passed through the pharynx and esophagus into the stomach.
The tongue presses against the hard palate, thus giving the bolus
(as the prepared mass is called) an impulse toward the isthmus
of the fauces; as it passes through this space the upper pharyngeal
constrictor muscle grasps it and passes it on — then the middle and

GASTRIC DIGESTION 159

the lower constrictors in turn — and it enters the esophagus.
(Meanwhile the soft palate has prevented it from going upward
and the epiglottis from entering the larynx.)

The muscles of the pharynx and upper esophagus, although striped,
are not absolutely under the control of the will; we may or may not
choose to swallow, but once begun the act completes itself, being beyond our
power to interrupt.

In the lower portion of the esophagus (about one-third) the
muscles are of the unstriped variety (this is the first appearance
of unstriped muscle in the alimentary tract, from this part on it
has no other kind) . The normal movements of unstriped muscle
are exactly suited to the requirements of the digestive process:
they are deliberate and slow instead of forcible and sudden, in
consequence of which they accomplish not only the passage but
the softening of the food by the admixture of mucus and water,
thus facilitating the contact of the digestive fluid with the whole
mass. Through the cardiac sphincter of the esophagus it enters
the stomach. It is first swept to the fundus, which serves as a
storehouse while successive portions of the food are acted upon.
In the stomach the mechanical process consists in the action of
the muscle coats, which move the food about that it may be
still more softened and thoroughly mixed with gastric juice. The
contractions of the muscles of the stomach go on in a wave-like
manner toward the pylorus, alternately constricting and relaxing
the walls of the cavity.

In the stomach the chemical process consists in conversion of
proteid foods into peptones and amino-acids. The digestive
fluid is gastric juice. The enzymes are pepsin and rennin. These
act upon proteins after they have been acidulated, and finally
reduce them to peptones. (Some protein food may be absorbed
as peptone but the greater part is reduced to still simpler forms,
as amino-acids, etc.)

Pepsin cannot act in alkaline fluids; gastric juice is acid (hydro-
chloric acid is essential).

In the digestion of meats, the acid softens the connective tissue
fibers (which are already partially gelatinized by cooking) and
thus prepares them for the action of the pepsin. Eggs are digested
in the same manner but more easily, having so little connective
tissue.

160 ANATOMY AND PHYSIOLOGY

Milk is first acted upon by rennin which sets free the albumin
contained and brings out the casein from the caseinogen, in the
form of a soft coagulum or curd. Pepsin then transforms both
albumin and curd into peptone.

Clinical Note. — The curdled milk which a healthy baby regurgitates is a
normal substance; the rennin has acted and it only needs the pepsin to com-
plete its digestion.

The protein of vegetables is digested in the stomach after the
cellulose fibers are softened by the acid. Starch may undergo
some slight degree of change in the stomach by the action of
the saliva which was mixed with it in the mouth, the ptyalin re-
maining active until the food becomes acidified.

Fats are freed from their connective tissue envelopes and float
as little globules; they are not digested here (to any great extent —
this is still uncertain).

Note. — The mineral salts do not require digestion. They are already
dissolved in the water for the purpose of entering into combinations in the
tissues. The same is true of grape sugar (dextrose).

When any portion of the stomach contents is Sufficiently pre-
pared by gastric digestion, the pyloric sphincter relaxes and the
rather thick yellowish fluid called chyme passes through it into the
duodenum and thence into the jejunum and ileum.

Chyme contains partially digested starch and proteins, as well
as sugars, peptones, fats, water and mineral salts, gastric juice
and some mucus.

The acidity of the chyme when it reaches the pylorus causes the con-
traction of certain muscles of the stomach which open the sphincter and allow
the flow of chyme into the duodenum, and thence into the ileum.

In the intestine the mechanical process is a continuation of the
peristaltic movement of the stomach. The circular fibers, by fre-
quent constrictions of the tube, divide the mass and force it along,
at the same time preventing a too rapid passage. The longitudi-
nal fibers assist, by a series of wave-like contractions.

The chemical process consists in the further digestion of pro-
teins, sugars and starch; also the digestion of fats.

The intestinal fluid is a mixture of intestinal juice, pancre-
atic juice and bile, therefore it contains several ferments or
enzymes. It is most active in the duodenum.

INTESTINAL DIGESTION l6l

Intestinal juice (succus entericus] completes the digestion of
proteins and sugar, also of starch. It is an alkaline fluid
secreted by the small glands of the intestine, namely — the glands
of Brunner and the follicles of Lieberkuhn or intestinal glands. It
contains several enzymes, erepsin, maltase, invertase and others.

By erepsin the continuation of protein digestion is carried on,
by maltase and invertase the maltose formed in the mouth from
starch is converted into dextrose.

Pancreatic juice is an alkaline fluid secreted by the pancreas.
Its enzymes are several in number, the most important being
trypsin, amylopsin and steapsin. Trypsin completes the digestion
of proteins already begun in the stomach, carrying it still further
by splitting those peptones which were not absorbed, into amino-
acids. (Trypsin digestion is important.)

Amylopsin (pancreatic diastase) acts like ptyalin (or salivary
diastase) converting starch into dextrose. The principal digestion
of starch is accomplished here.

Steapsin is the fat-splitting enzyme. Fats are probably
freed from their connective tissue envelopes before reaching the
intestine, and the steapsin splits them up into fatty acids and
glycerine. These fatty acids combine with the alkali of the
intestinal fluids to form soaps, which in solution are absorbable.
(Also soaps can emulsify the fats which continue to arrive, that is,
divide them into fine particles which will be suspended in the
alkaline solution.)

What becomes of the soaps? Some are absorbed as such,
some form an emulsion with other fats. An emulsion was long
believed to be the only form in which fat was absorbed, and this
is not yet disproven. At all events, fat still appears as a white
emulsion called chyle in the absorbing vessels of the small intestine.

The third important constituent of intestinal fluid is bile.
This is an alkaline fluid which enters the duodenum with the
pancreatic juice by the opening at the bile papilla.

When the chyme enters the duodenum, the acid which it contains causes
the opening of the valve of the common duct, and the bile flows into the
duodenum. As soon as the chyme is made alkaline (by bile and intestinal
fluid) the valve closes not to be again opened until another portion of acid
chyme is received from the stomach.

The bile contains no digestive enzymes.

1 62 ANATOMY AND PHYSIOLOGY

What, then, are the uses of the bile which is poured into the in-
testine with the pancreatic juice?

First, it is alkaline in reaction — the intestinal enzymes act in
an alkaline medium. Second, it holds the soaps in solution,
favoring their absorption. Third, it assists the fat-splitting func-
tion of steapsin and dissolves fatty acids so that they may be
absorbed. Fourth, it accelerates the digestion of fats. Fifth, it
delays putrefaction in the intestines, probably — in part — by assist-
ing peristalsis, and thus preventing stagnation of the whole
contents.

Clinical note. — Experiment and observation prove that the presence
of bile is necessary to nutrition. Without it a person may eat large quanti-
ties of food and still lose weight.

The work of digestion is continued in the jejunum, and to a
lesser degree in the ileum. By the absorption of digested food,
the intestinal contents are diminished in quantity and changed
in character, containing less water and approaching a firmer
consistency.

After passing through the jejunum and ileum into the large
intestine, some digestion may still go on by the action of the in-
testinal juice which was incorporated with the mass, but the
major portion of the contents of the colon consists of undigested
remnants and waste.

From the foregoing we gather the following summary:

Proteins are digested in the stomach and intestine. The
enzymes sue pepsin and rennin, trypsin, and erepsin. Products
of protein digestion, peptones and amino-acids.

Starches are digested in the mouth and the intestine. En-
zymes— ptyalin in the mouth, and amylopsin in the intestine.
Product, dextrose.

Sugars are digested in the mouth and intestine. Enzymes —
maltase in the mouth, and maltase and invertase in the intestine.
Final product, dextrose. Dextrose (glucose, grape sugar) and
levulose taken with the food, do not require to be changed; they
are already soluble and absorbable.

Fa/5 are freed from their connective tissue in the stomach,
and split or emulsified in the intestine. Products, glycerine and
fatty acids, fat-emulsion.

STIMULI OF DIGESTIVE GLANDS . 163

Vegetables are digested in the stomach so far as proteins are
concerned, their connective tissue having been previously softened.
Their starch and sugar content, and their oils — as above.

The best temperature for digestion is the normal temperature
of the interior of the body, or about 100° Fahrenheit.

Clinical note. — The reason for abstaining from ice-water during digestion
is that the various ferments cannot do their work in a temperature of much less
than 100° F. (If people will eat ice-cream after dinner they should take it
slowly, that the whole process of digestion be not too long delayed by the
necessity of waiting for the temperature to rise again to ioo°.)

Warm foods make less of a demand upon the vitality of the body than
cold ones.

The activity of the digestive glands (like that of all others) is
called forth by a stimulus of some sort conveyed to the gland cells
by sympathetic nerves.

In the case of the salivary glands this stimulus is aroused
by several things — first, by the presence of food in the mouth;
second, by the introduction of substances which have an agree-
able flavor or odor; third, by movements of the muscles of mas-
tication; fourth, by the sensation of nausea; fifth, by the thought
of food (which is a psychic stimulus'). The salivary secretion is
diminished in fevers and wasting diseases, also by certain psychic
impressions — as fear, anger, anxiety, and the like. Everyone
knows the dry mouth of strong emotion, especially if associated
with apprehension.

The gastric glands respond in a similar manner; the presence of
food in the stomach causes a strong flow, flavors and odors assist.
Small amounts of bitter flavors in food increase it, aromatic
substances have the same effect.

Clinical note. — These do not act at once; therefore aromatic or strongly
flavored medicines should be given a quarter of an hour or more before meals
in order to ensure the best result.

Water increases the flow. The habit of taking water before
meals is a good one, but if taken immediately before the quantity
should be small. Alcohol, like the bitters, also stimulates the
flow of gastric juice.

The thought of food causes the psychic flow. Strong desire
for food, or appetite, causes a psychic flow of very active juice within

164 ANATOMY AND PHYSIOLOGY

four and one-half minutes. The thought of distasteful food
inhibits the flow of gastric juice, as do nauseous flavors and odors.

Clinical note. — The sense of distaste diminishes the flow of gastric juice,
therefore it would seem wise to avoid forcing a patient to take more than
the minimum necessary quantity of food while the distaste is marked.

Pepsin is sensitive to alkalies. Alkalies and malts may favor
a flow of gastric juice, but if given during digestion, they destroy
the pepsin.

Proteins always soften when treated with water, and become
transparent before they can be dissolved; salty foods do not easily
soften — they are not easily digested. This is the reason why it
is well to precede the cooking of dry and salty foods by soaking
in water.

The presence of ordinary fat delays digestion in the stomach,
although a very finely divided fat, as in cream or the yolk of
egg, may be there partially digested by a ferment called gastric
steapsin.

An accumulation of stomach contents is embarrassing to the
gastric juice, hence the advisability of deliberation when taking
one's meals.

Note. — Hemoglobin is split by pepsin into hematin and a globin. The
hematin gives the dark color to the blood which is vomited after gas-
tric hemorrhage, and also to that which appears in feces after intestinal
hemorrhage. (Hemoglobin is contained in the red cells of the blood.)

The passage of food through the intestine is normally slow, and
thus it is fully exposed to the surfaces of the circular folds of the
mucous membrane. By the absorption of digested food the intes-
tinal contents are diminished in quantity and changed in character,
containing less water and approaching a firmer consistency. After
passing through the ileo-colic sphincter into the large intestine
there is little but waste remaining, undigested food forming the
major portion. This collection of waste, liquids, coloring matter
and undigested food is called feces. The coloring matter is derived
partly from bile, partly from food. (It may be modified by drugs ;
for example, iron and bismuth give a black color to the feces.)
(The odor is due to sulphuretted hydrogen and to skatol — it also is
modified by food.) The consistency depends upon the amounts of
water and mucus, approaching a liquid form when the intestinal

DIGESTIVE ENZYMES 165

contents are hurried through the tube before absorption can take
place.

Defecation is the act of expelling the feces. The bowel muscles
contract and the sphincter ani relaxes; the abdominal muscles
assist by compressing the organs from above. The dietary which
contains the largest proportion of waste material will leave the
greatest quantity of feces and lead to more frequent defecation
than one which is made up of digestible substances only. The
peristaltic action of the bowel is made more effective by the pres-
ence of a reasonable amount of matter to be acted upon.

Clinical notes. — Diarrhea is the passing of frequent loose or watery stools.
It occurs when the contents of the small intestine are hurried along too
rapidly by some irritating substance which causes excessive peristalsis and
a leakage of the watery portion of the blood.

Constipation is caused by a too concentrated diet and slow peristalsis.
Since bile is a natural stimulant to the muscles of the bowel, constipation is
often associated with a torpid liver; it is also caused by lack of fluids in the
bowel. Therefore this is one reason why water is an important food.

Origin of enzymes of the digestive fluids. — They are formed,
usually, within the glandular cells of the organs which secrete
the fluids. Sometimes, by the fusion of a substance derived from
the cell with another called a pro-enzyme which it meets in the
fluid.

For instance, the pancreas secretes two enzymes — amylopsin and steapsin.
It also secretes trypsinogen, a pro-enzyme which unites with a special sub-
stance in the intestine to form the enzyme trypsin. In the one case (that
of amylopsin or of steapsin) the enzyme leaves the cells already formed, in
the other (that of trypsin) it is formed outside of the cells.

As each digestive organ secretes its own fluid, so each fluid con-
tains its special enzymes for special purposes. For instance, the
enzymes or ferments of saliva cause rapid digestion of starches,
but not of eggs or meat. Those of the gastric juice assist the
digestion of eggs or meats, but not of starches.

While it would probably be possible to digest the foods by the
use of chemical substances alone, as acids or alkalies, the process
would require such a high temperature that the body could not
endure it, and it would be so slow that we might starve while
waiting. The presence of enzymes not only accelerates the process
of digestion, but allows it to go on at the body temperature, hence
their great importance.

1 66 ANATOMY AND PHYSIOLOGY

The nature of the changes which the food must undergo is, a separation
or splitting into simpler bodies. Most food substances are complex and
insoluble. The object of digestion is to convert them into simple and soluble
substances which can be absorbed. In order to accomplish this, they must
be not only mixed with water, which is a mechanical process, but combined
with it or hydrolysed which is a chemical process. The digestive enzymes
belong to the class called hydrolytic enzymes because they act by hydrolysis.

Hydrolysis means decomposing the water which is present and uniting its
elements, H and 0, with other substances (also in process of decomposition or
breaking down by the action of the same enzyme).

According to Hammarsten, no glands in the body can work
so rapidly, can produce so great a quantity of fluid in the same
time as the salivary glands, not even the kidneys. Eight to four-
teen times the weight of all the glands together may be produced
within one hour.

Saliva has the power of splitting sulphureted hydrogen from
the sulphur oils of onions, radishes, etc.

Clinical note. — Ptyalin exists in the saliva at birth but does not become
active under three or four months of age.

SUMMARY

Digestion. — Is the process of so changing the food that it may
be absorbed.

Absorption.- — Is the process of taking up certain substances
and conveying them to the blood.

Circulation. — Is the process of carrying the blood and other
substances to every part of the body.

Assimilation. — Is the process which goes on in the tissue cells
whereby they make use of the food which is conveyed to them.

We have now to study the organs which distribute the products
of digestion, and the composition of the food-bearing fluids —
blood and lymph. Assimilation is nature's own secret, not yet
revealed to the mind of man. This is a phase of metabolism.

ABSORPTION OF FOOD

Accompanying the digestion of food the absorption of nutritive
principles takes place.

It is quite possible that some portion of the sugars is taken up
by blood-vessels of the stomach, and it is probable that more or less

ABSORPTION OF FOOD 167

of the water and dissolved salts are here absorbed, but most of the
stomach contents pass through the pylorus as chyme and are re-
ceived by the duodenum to be acted upon by intestinal fluids and
prepared for absorption. The villi (Fig. 113) are the absorbents
which perform this function in the intestine. The epithelial cells
with which they are covered take up and^transmit the new sub-

FIG. 113. — SECTION OP INJECTED SMALL INTESTINE OF CAT. a. b. Mucosa.

Villi. *. Their absorbent vessels, h. Simple follicles, c. Muscularis mucosae.

Submucosa. g, 6. Circular and longitudinal layers of muscle. /. Fibrous coat.

All the dark lines represent blood-vessels filled with the injection mass. — (Piersol.)

stances into lymph spaces within the villus, from which they go
either into the blood-vessels or lymph capillaries which the villus
contains.

Water and mineral salts (dissolved in the water). — These must pass into
the blood capillaries, thence into veins, and through them to the portal vein
(page 167). By this they are taken to the liver,

Sugars pass by the same route, namely, blood capillaries and veins to
the liver from the intestine".

1 68 ANATOMY AND PHYSIOLOGY

Peptones and their products, amino-acids, also find their way in the same
manner to the portal blood and the liver, from the intestine.

Thus it appears that all proteins, sugars, water and salts pass
through the liver. There, water and salts are used for various
combinations; sugars are converted into glycjjgen to a great extent
and stored for future use; and proteins furnish tissue food and
materials for bile.

Glycogen. — This product of the action of liver cells upon carbohydrates is
stored in the liver. When needed it is returned to the blood (as sugar again)
and distributed to the tissues, notably to the muscles. Being readily oxidized
it favors the rapid changes in muscles which result in motion. Therefore, it
follows that sugar and starch are sources of muscle energy.

Lacteals

Blood vessels

FIG. 114. — LOOP OF SMALL INTESTINE WITH LACTEALS. — (Morris.)

Urea. — This is another substance which appears as a result of the activity
of the liver cell. It is one of the final forms of waste derived from the
metabolism of protein substances. It is a very poisonous waste and is; elim-
inated from the blood by the kidneys.

Having yielded materials for these functions, the remaining
food substances are carried away from the liver by hepatic veins
and finally into the general circulation, to be distributed to the
tissues of the body.

There remain the fats: These, being transferred by the epithe-
lial cells to the lymph-spaces, take the other route, in the form of
an emulsion known as chyle. They pass into the lymph capillaries

ABSORBENT VESSELS

l6Q

FIG. 115. — DIAGRAM SHOWING THE ROUTES BY WHICH THE ABSORBED FOODS
REACH THE BLOOD OF THE GENERAL CIRCULATION (G. Bachman). I. i., Loop of
small intestine; int.v., intestinal veins converging to form in part, p. v., the portal
vein, which enters the liver and by repeated branchings assists in the formation of
the -hepatic capillary plexus; h. v., the hepatic veins carrying blood from the liver
and discharging it into, inf. v. c., the inferior vena cava; int. I. v., the intestinal
lymph vessels converging to discharge their contents, .chyle, into rec. c. the receptac-
ulum chyli, the lower expanded part of the thoracic duct; th. d., the thoracic duct
discharging lymph and chyle into the blood at the junction of the internal jugular
and subdavian veins; sup. v. c., the superior vena cava. — (From Brubaker's Text-
book of Physiology.)

1 70 ANATOMY AND PHYSIOLOGY

of the intestine (so-called lacteals}, which open into the lymph
vessels in the submucous coat. By these vessels the chyle finally
reaches the thoracic duct and is carried to the blood, to be distrib-
uted to the tissues of the body by way of the general circulation.

Osmosis

The forces which regulate absorption include the process of
osmosis, which has been described as the passage of "diffusion
streams" whereby solutions of different strengths or densities
pass through animal membranes. This does not explain all that
happens; it is recognized that certain very important chemical
processes must be involved in the cell walls of the intestines, the
nature of which is beyond our present understanding. We
bid farewell to peptones and amino-acids in the intestinal canal
and greet albumins and fats in the blood-vessels which leave it;
we find solutions of soaps and fatty acids on the outside of the
villus — emulsified fat in the lymph tube within.

The same forces by which the nutritive fluids were absorbed
into the vessels, are again at work to effect their transference
from the vessels to the tissues of the body.

In the tissues. — The solution of nutritive substances, having
been carried by the blood-vessels to the minutest channels in the
body, passes into the tissue spaces as lymph, which bathes the cells
themselves, so that they may receive the material necessary for
their action and upbuilding.

Different tissues appropriate their different foods, and each
gives back the products of its own activities as tissue "wastes,
which in turn enter the blood to be carried to tissues which can
make another use of them, or to organs which can dispose of them
as excretions.

The next chapter will introduce the study of the blood, heart
and blood-vessels, or the system of circulatory organs for dis-
tributing the blood throughout the body.

CHAPTER X
THE BLOOD AND CIRCULATORY ORGANS

THE BLOOD

The blood is the most important fluid in the body. It not only
carries food to every part, but bears waste matters to those
organs which can dispose of them in the form of excretions. It
consists of a clear yellowish fluid called plasma and small round
cells (invisible to the naked eye) called corpuscles (little bodies),
which float in the plasma. The corpuscles are of two sorts, red
and white.

FIG. 1 1 6. — CORPUSCLES OF BLOOD, AS SEEN UNDER THE MICROSCOPE.
Four white ones are shown. The red ones have a tendency to form rows. — (Funke

and Brubaker.)

It is convenient to follow the usage common in clinical work and speak of
them as red and white cells.

Blood has a characteristic odor which varies in different animals.

The temperature of the blood is about 100° F.

The reaction is alkaline.

The red cells (erythrocytes) are non-nucleated, flexible and
elastic. They are very numerous, numbering 4,000,000 to
4,500,000 in a cubic millimeter. They measure about -^^ of
an inch in diameter, and their shape has been usually described

171

172

ANATOMY AND PHYSIOLOGY

as that of a flattened sphere (Fig. 116). (They are oxygen-
carriers.)

Note. — The illustration presents the appearance under the microscope
of blood which has been removed for a time from the vessels and cooled.
Careful studies under other conditions indicate that the living ceils are
slightly bell-shaped. In the early stage of formation they contain a nucleus.

The red cells are composed largely of hemoglobin held in a net-
work or stroma of protoplasm. This itself is amber colored, but
when a great number of cells are together as in a drop of blood,

FIG. 117. — WHITE CORPUSCLES PENETRATING CAPILLARY WALLS. —
(Landois and Stirling.)

it gives the red hue to the fluid. The color varies with the
quantity of oxygen in the cell, from bright scarlet with much
oxygen to bluish red with little. Hemoglobin is a protein substance
whose most important property is its power to combine with
oxygen forming oxy-hemoglobin, and to give it up. It contains
a minute quantity of iron in combination (hematiri) which is neces-
sary to life processes.

The origin of the red cells is in the red marrow of cancellous
bone.

The white cells or leucocytes are of different sizes (the average
size, about -2^00 of an inch in diameter). They move more slowly
in the plasma and are far less numerous, numbering only about
7500 in a cubic millimeter.

They are nucleated, flexible and elastic. Their shape is spher-
ical (often irregular), and they consist of a transparent material
containing one or several nuclei and many fine granules of protein
substances of several kinds. They also contain glycogen and
enzymes.

THE LEUCOCYTES 173

The white cells frequently change their shapes by means of
ameboid movements, that is, like the ameba, they thrust out portions
of their substance and draw them back. They can send out little
prolongations and draw floating particles to themselves, or they
can wrap themselves around foreign substances.

They possess also the power of slipping (squeezing) through the
walls of capillary vessels. This is called diapedesis (Fig. 117).

Of the several varieties of leucocytes the percentage of polymorpho-
nuclear cells (nuclei of many shapes) is the largest.

The polymorphonuclear cells (oftenest called polynuclear} and
the lymphocytes are called phagocytes, because they destroy
bacteria by absorbing and digesting them. This process is called
phagocytosis (to be referred to later on) (pp. 214 and 220).

The origin of the white cells is from two sources: the lymphocytes
originate in lymph glands and other lymphoid tissues; the poly-
nuclear leucocytes and others are developed from cells in the marrow
of long bones. A third form of colorless cell is called a blood plate
or platelet.

The platelets are very small, being barely one-half the size of
the ordinary cells. They are similar to leucocytes; their origin
is not understood, but they take an important part in the coagu-
lation of blood.

The plasma is a thin watery saline fluid in which the corpuscles
float. It contains both nutritive and waste matters in solution,
and certain elements from which fibrin is derived, also enzymes
(and certain extractives). Fibrin is essential to the production
of a blood-clot, without which hemorrhage would never cease of its
own accord. (Fibrin and corpuscles removed — serum remains.)

The substances dissolved in the watery portion of the plasma are:

Proteins (chiefly)

Nutritive (derived from food) . .

Serum-albumin
Paraglobulin
Fibrinogen
Prothrombin (or
Thrombogeri)

Sugars
Fats

Waste products (derived from f Urea

\ Extractives \ TT . . ,

tissue changes). ( Unc acid, etc

f Sodium

Mineral salts. Chiefly salts of \ Potassium

1 Calcium

174 ANATOMY AND PHYSIOLOGY

The serum-albumin is the great tissue builder. The fibrinogen
is a fibrin maker (paraglobulin may assist, its use is not fully
known).

Sugars and fats are tissue foods and sources of heat.

Mineral salts preserve the necessary alkalinity of the blood and
assist in the formation of certain tissues (as bone). Sodium
chloride (common salt) is the most abundant and to this is due the
salinity of the blood.1 Salinity is an exceedingly important
quality of plasma. It is essential to the interchange of fluids
between the vessels and the tissues and to the maintenance of
the rhythmic action of cardiac muscle. It is also necessary for
the preservation of blood corpuscles. Pure water invades them
(by osmosis) and so dilutes them that they swell and are de-
stroyed. The salinity of plasma is the same as that of the cells,
therefore no "diffusion streams" (or osmosis) can occur and the
cells are safe. For Coagulation of Blood see p. 217.

THE CIRCULATORY ORGANS OF THE BLOOD

This system includes the heart and blood-vessels (arteries,
capillaries and veins). They are the organs which contain the
blood.

The heart is a pump. The arteries are elastic tubes which re-
ceive the blood directly from the heart. The capillaries are small
vessels into which the arteries lead, and the veins carry the blood
from the capillaries back to the heart.

Arteries. — Vessels which convey the blood away from the heart.
They are flexible tubes whose walls consist of three layers or
coats — external, middle, and internal (or tunica adventitia, tunica
media, and tunica intima). The external coat is composed of
fibrous tissue to which the strength and toughness of the vessel is
due; the middle is composed of elastic tissue and unstriped muscle
fibers, giving to arteries their yielding and contractile chracter;
the internal is thin and smooth and is a continuation of the lining
of the heart. Arteries of medium size have most muscle tissue,
while the larger ones have most elastic tissue. It is owing to
their elasticity that arteries remain open when they are empty
or cut across.

1 A "normal saline solution" contains salt in the proportion found in blood.

CAPILLARIES — VELNS 175

Note. — The internal coat is the only one which is continuous throughout
the entire circulatory system.

Surgical note. — When a ligature is tied tightly around an artery the middle
coat may be felt to break down under the cord, while the external one remains
whole, owing to its toughness.

The arteries give off branches which divide and subdivide until
the smallest ones can be seen only with the microscope — they are
called arterioles. The arterioles lead to the vessels which are
smallest of all — the capillaries.

Capillaries. — Vessels which receive blood from the arteries and
carry it to the veins. They exist in nearly every part of the body,
except cartilages, hair, nails, cuticle, and the cornea of the eye.
Their walls have only the internal coat, a single layer of cells —
endothelium. It is through this thin wall that the work of
exchange is performed between the blood and the various tissues of
the body, nutritive material being taken from the blood and certain
waste substances being returned to it. To provide vessels for this
exchange is the function of the capillaries. They are most numer-
ous where most work is to be done, viz., in the lungs, skin, mucous
membranes, liver, kidneys and glands.

Their average diameter is WT¥ of an inch — just enough to permit the easy
passage of the corpuscles. They are uniform in size, neither increasing nor
diminishing in caliber.

Veins. — The vessels which gather the blood from the capil-
laries and carry it to the heart; they are formed by the uniting of
capillaries.

They are at first very small (called venules or venous radicles) but constantly
grow larger by uniting with each other, although they often branch and
reunite.

Veins, like arteries, have three coats, but their middle coat is
neither so elastic nor so muscular, so that they are softer, and when
empty or cut, they collapse. The inner coat of the veins presents,
at intervals, semilunar folds, making pockets called valves, which
allow the blood to flow toward the heart, but prevent it from setting
backward freely. If the veins are very well filled the location of
the valves may be recognized by an appearance of puffing out at

iy6

ANATOMY AND PHYSIOLOGY

those points where they exist (Fig. 118), as the blood fills the
pockets from above.

Blood-vessels possess nerves (the vaso-motors) which, by con-
trolling the muscular coats, regulate the amount of blood flowing
through them at a given time to the structures which they

supply. (An organ at work needs more blood

than an organ at rest.)

They also possess tiny blood-vessels in their walls,
the vasa vasorum.

All blood-vessels have sheaths of connective
tissue. In the case of the larger ones these are
quite strong and sometimes inclose a vein, an
artery, and a nerve together for protection.

THE HEART

The heart is a hollow muscular organ through
which the blood passes, placed behind the ster-
num and just above the central tendon of the
_A diaphragm. Its average size is about five

VEIN LAID OPEN TO inches long by three and one-half wide, and two
SHOW VALVES. , , ir ,,. ,

and one-half thick.

Note. — The muscle tissue of the heart is called the myocardium.

It is shaped like a cone, about five inches long and three and
one-half inches wide, with the base turned upward toward the right
shoulder and the apex pointing downward toward the left side.
It is composed of several layers of muscle fibers which are peculiar,
being involuntary and at the same time striped. teA/XrtXjjQ/^

The cavity of the heart is divided by a septum into right and
left portions, and as it lies in the body the right heart is nearly in
front of the left. Each side consists of two chambers, an auricle
(atrium) and a ventricle (ventriculum) (Fig. 120).

The auricles receive blood and pass it into the ventricles.
Their walls are thin and flabby. The right auricle, or atrium,
presents two large openings for the entrance of veins, and one for
communication with the right ventricle. The veins are the
superior vena cava from the head and upper extremities; the inferior

THE VENTRICLES

177

vena cava from the trunk and lower extremities. It also has a
transverse fold on the posterior wall called the Eustachian valve
or valve of the inferior vena cava, and a round depression on the
septum between the two auricles (atria), called the oval fossa (fossa
ovalis). The left auricle presents two large openings and several
small ones for veins, and communicates with the left ventricle.

Posterior branch of
right coronary ar-
tery

Auricular appendage
Right coronary artery

Preventricular branch
Right marginal branch

Posterior interventicu-
lar branch of right
coronary artery

Transverse branch of
right coronary artery

Left coronary artery

Anterior interventricu-
lar branch of left
coronary artery

Left marginal branch

FIG. 119. — ANTERIOR SURFACE OF HEART. — (Morris.)
The coronary arteries supply the substance -of the heart.

The ventricles expel blood from the heart. They include the
apex of the heart; their walls are thick and strong, the left one
being the thicker and larger of the two. Certain muscle-fibers in
the ventricles pass downward to wind around the apex of the heart
and then turn upward; others are transverse, still others oblique;
the arrangement causing the heart to harden in contraction, with a
twisting motion from right to left and a forcible pressure against
the chest wall. This is felt in the fifth interspace, at the left of the
sternum and is called the cardiac impulse.

The muscle band of His (auricula-ventricular bundle) is a name
given to a bundle of muscle fibers which connects the auricles and
ventricles; the contraction impulse is believed to travel from auricle
to ventricle by these fibers.

13

i78

ANATOMY AND PHYSIOLOGY

The interior of the ventricles is marked with a number of ridges
or bands of muscle fibers (the trabecultz earned), and certain of
these are attached by tendinous cords to the valves of the heart.
Each ventricle opens into a large artery, which conveys the blood
away — the pulmonary artery from the right ventricle, the aorta
from the left.

FIG. 1 20. — INTERIOR OF LEFT HEART. (Observe the difference in thickness of

the walls in auricle and ventricle.) — (Allen Thomson in Brubaker.)
i, L. atrium or auricle; 2, division between it and ventricle; 3^wall of left ventricle;
4, a band of muscle fibers severed; 5, other muscle bands; 6, a leaflet of mitral valve,
with tendinous cords; 7, aorta (a large artery) laid open to show semilunar valves; 8,
pulmonary artery (semilunar valves closed) ; 9, arch of aorta.

Note. — In the new nomenclature the name "atrium," or forechamber, is
given to the main part of the auricle, and the word auricle applies to the
auricular appendage alone.

Endocardium. — The lining of the heart. It is thin and firm,
resembling serous membrane in appearance, and is continuous
with the lining of the blood-vessels, thus making a perfectly

CARDIAC VALVES 1 79

smooth surface of endothelium throughout, for the current of blood
in heart and vessels.

THE VALVES OF THE HEART

The valves of the heart are formed by folds of endocardium
strengthened by fibrous tissue and attached to fibrous rings around
certain orifices of the different chambers — two in the right heart
and two in the left. The opening between the right auricle and
ventricle, or tricuspid orifice, is guarded by the tricuspid valve,
which is composed of three leaflets. It allows the blood to flow
down into the ventricle but prevents it from flowing back. The
opening between the left auricle and ventricle, or mitral orifice, is
guarded by the bicuspid (or mitral) valve, composed of two leaflets,

FIG. 121. — VALVES OP THE HEART.

i. Right auriculo- ventricular orifice, closed by the tricuspid valve. 2. Fibrous
ring. 3. Left auriculo-ventricular orifice, closed by the mitral valve. 4. Fibrous
ring. 5. Aortic orifice and valves. 6. Pulmonic orifice and valves. 7, 8, 9,
Muscular fibers (auricles removed). — (Bonamy and Beau.)

allowing the blood to flow down into the ventricle but not to
return. (Both the. tricuspid and mitral valves are connected to
certain muscle bands of the ventricles by tendinous cords which
control the motion of the leaflets, preventing them from flying
upward too far when the ventricles contract.) (Fig. 120.)

The opening from the right ventricle into the artery which
leaves it (pulmonary artery), is guarded by three semilunar valves,
which are half-moon shaped pockets called the pulmonary valves.
Likewise the opening from the left ventricle into its artery (aorta)
is guarded by three semilunar valves called the aortic valves
(Fig. 121).

i8o

ANATOMY AND PHYSIOLOGY

The semilunar valves allow the blood to flow in one direction
only — that is, away from the heart.

FUNCTIONS OF THE CHAMBERS OF THE HEART

The auricles, having received blood from the veins opening into
them (the right — blood from entire body; left — from lungs alone)
gently contract together to send it down into the ventricles;
quickly the ventricles contract, forcibly and together, expelling
blood into the two large arteries — the pulmonary carrying it to the
lungs, the aorta to all parts of the body. This process is' the systole
of the heart; it occupies about eight-tenths of a second,fperhaps a

FIG. 122. (DIAGRAM.)

The right auricle receiving blood and passing it through tricuspid valve into right
ventricle, which is dilated (semilunar valves closed). — (Dalton in Brubaker.)

trifle more. Then comes the resting-time when the heart is dilat-
ing and filling again, called the diastole of the heart.

One systole and one diastole together constitute a cycle of
the heart.

During the systole of the auricles, the tricuspid and mitral
valves are open and the semilunar valves are closed. During
systole of the ventricles the tricuspid and mitral valves close, and
the semilunar valves are open (Figs. 122, 123). See Heart Sounds
(closure of valves} .

The thickness of the ventricle wall is explained by the need for

THE PULSE l8l

sending blood to a distance, the greater thickness of the left being
made necessary by the far greater work required of it.

The activity of the heart is unlike that of any other organ in its
periods of working and resting. The nerve-muscle structure is so
arranged that a series of rhythmic contractions at short intervals,
goes on continuously day and night from the beginning of life to
its close.

The systole of the ventricles corresponds to the "heart-beat."
It occurs at perfectly regular intervals in health, the rate being

FIG. 123.

The right ventricle filled, contracts and expels blood through semilunar valves
(tricuspid valve closed}. — (Dalton in Brubaker.)

from sixty to seventy per minute in men, and from seventy to
eighty in women. The heart's action is more rapid in the upright
position than in sitting or lying, and is increased by any exercise,
however gentle. Excitement or emotion will quicken it at once,
and it is always faster in children, being about one hundred and
forty in the newly born and reaching an average rate of ninety
to one hundred at the age of three years; ninety in youth, sev-
enty in adults, and eighty in old age. The innervation of the
heart is described on pages 185, 186.

The Pulse. — The effect of the heart-beat upon the current of
the blood may be felt in the arteries, which are distended for an
instant by the blood forced into them as the ventricles contract.

182

ANATOMY AND PHYSIOLOGY

This gives the effect of a beating in the arteries, which is called the
pulse. The pulse-rate corresponds with the heart-beat; therefore,
the rate and force of the heart's action are judged by means of the
pulse.

The Heart Sounds

The action of the heart causes certain sounds, named the first
and second. The first accompanies the sudden closure of the tri-
cuspid and mitral valves, as the ventricles contract. It is the

UPPER ATTACHMENT
1 OF PERICARDIUM

• RANCHES OF PUL-
MONARY ARTERY

AORTA--.

BRANCHES OF
LMONARY ARTERY
..-PULMONARY
ARTERY

DIAPHRAGM PERICARDIUM

RIGHT ATTACHMENT OF
VENTRICLE PERICARDIUM
TO DIAPHRAGM

DIAPHRAGM

FIG. 124. — The heart in situ. The pericardium has been cut open in front, and

reflected.— (Testut.)

systolic sound — caused by the systole of the ventricles. The sec-
ond accompanies the sudden closure of the semilunar valves. It
is the diastolic sound, occurring with the diastole of the ventricles.
The first or systolic sound is the louder and larger, being due to
the contracting of muscle fibers as well as to closure of valves.
The second, diastolic sound is short and sharp, due to valve closure
only. The two sounds are compared to the spoken words — lubb
dupp.

THE PERICARDIUM 183

When the blood is forced into the elastic arteries by a contraction or
beating of the heart it stretches them. When the contraction is ended, the
wall of the artery recoils and there is a setting back of the blood for an instant
toward the heart, but it is stopped by the closing semilunar valves, which thus
make the second sound.

Clinical note. — If the valves of the heart are rough, the sounds are changed
by a "murmur." If they cannot close perfectly, a portion of the blood will
flow backward instead of going forward, and this is regurgitation. This, also,
changes the sound of a valve and causes a murmur.

The pericardium (Fig. 124). — A loose serous sac enclosing the
heart. The layer which closely covers the heart, or the visceral
layer, is the epicardium. It covers the aorta and pulmonary arte-
ries for about one inch, then leaves them to become the parietal
layer or lining of the fibrous sac which encloses the whole, and
which is closely attached to the diaphragm below and the great
vessels above. A small quantity of pericardial fluid prevents fric-
tion between the surfaces, as the smoothly covered heart beats in
the smoothly lined cavity; this increases in inflammation of the
pericardium, or pericarditis, and it is sometimes necessary to
remove it by tapping.

REVIEW. — PRINCIPAL POINTS OF INTEREST IN THE HEART
t RIGHT AURICLE

Openings of two large veins bringing blood from the body.
Opening of coronary sinus bringing blood from the heart itself.
Oval fossa and annulus ovalis (or oval ring).
Eustachian valve (or valve of inferior vena'cava).
Tricuspid orifice with tricuspid valve.

RIGHT VENTRICLE

Tricuspid orifice and tricuspid valve.
Opening for pulmonary artery, and pulmonary valves.
Trabeculae carneae (fleshy bands) , and the tendinous cords con-
necting them with tricuspid valve.

LEFT AURICLE

Openings of three or four pulmonary veins.
Mitral orifice with bicuspid (or mitral) valve.

1 84

ANATOMY AND PHYSIOLOGY

LEFT VENTRICLE

Mitral orifice and bicuspid valve.
Opening for aorta and aortic valves.

Trabeculae carneae and the tendinous cords connecting them
with the bicuspid valve.

THE COURSE OF THE BLOOD THROUGH THE HEART

Resume. — The blood enters the right auricle, passes down into
the right ventricle, and out through the pulmonary artery to the

Left carotid artery

Left subclavia _
artery

Aorta

Pulmonary artery

Pulmonary vans
from left lung

Left auricle

Coronary vessels'

Anonyma

Superior vena cava

Pulmonary veins
from right lung

Right auricle

Inferior vena cava

Coronary artery

FIG. 125. — POSTERIOR SURFACE OF HEART.
Pulmonary veins bringing pure blood to left auricle. — (Morris' Anatomy.)

lungs; it returns by the pulmonary veins to the left auricle, passes
down into the left ventricle, and out through the aorta to every
part of the body, from which it is returned by two large veins to
the right auricle again.

CARDIAC NERVES 185

The course from the right ventricle through the lungs and back
to the left auricle is called the pulmonary circulation (Figs. 125 and
160).

The course from the left ventricle through the entire body or
"system" and .back to the right auricle is called the systemic
circulation or main circulation (Fig. 126).

Important notes. — Pure blood is carried from the heart through the
systemic arteries to all tissues in the body to nourish them. This blood is
called arterial blood; it is bright red in color. The term pure blood and
arterial blood are used to signify one and the same thing.

Impure blood from the tissues of the body is returned to the heart by the
systemic veins. It is called venous blood; it is purple-red or blue in color and
contains waste matters. The terms impure blood and venous blood are used to
signify one and the same thing.

The venous blood from the body is poured into the right side of the heart,
from which the pulmonary artery conveys it to the lungs. Consequently the
pulmonary artery is unlike others, because it carries venous blood from the
heart; and the pulmonary veins are unlike others because they carry arterial
blood to the heart.

Innervation of the heart. — As already mentioned, p. 176, the
heart muscle or myocardium has a structure peculiar to itself.
Anatomically its fibers differ from those of other muscles in size
and arrangement; physiologically it is unlike any other striped
muscle in the body, being involuntary although striped. Cardiac
muscle responds to the stimulus brought by two sets of nerves,
called accelerator and inhibitor nerves. By the accelerator nerves
the rapidity of the heart-beat is increased; by the inhibitors it is
slowed. These nerves are branches of the pneumo gastric or vagus
nerve. A long unsettled question is, whether in the absence of
these, the heart would still beat under the chemical stimulus alone
of tissue change. Years of experimentation and observation
incline scientists to believe that this is possible.

The heart muscle of cold-blooded animals performs rhythmic contractions
for several hours after removal from the body; to insure this action it is only
necessary to keep it moistened in a mixture of calcium, potassium, and sodium
salts in solution. The chemical action between this fluid and that within the
cells is sumcient to produce contractions, following each other in rhythmic
order.

So in life, an interchange of chemical products between lymph and cell
contents may furnish a stimulus which keeps the heart in action, the

1 86 ANATOMY AND PHYSIOLOGY

function of the nerves being to accurately regulate the rate at which con-
tractions occur. This is the myogenic theory of the cause of the heart beat.
Another theory, not so generally held, is the neurogenic, which assumes a
special nerve system in the myocardium, acting automatically and regulated
or modified by accelerator and inhibitor nerves as above described.

The velocity of the normal blood current is greatest in the larger
arteries and least in the capillaries. It increases in the larger
veins but never equals that in the arteries. The time required for
the entire circuit from heart to heart again, is about twenty-eight
seconds, or approximately, in the time of twenty-six to twenty-
eight heart-beats.

The onward How of the current, as it is expelled from the heart,
is assisted by i, the elastic recoil of the arterial walls (after the
stretching caused by the blood which is pumped into them with
each systole), 2, the pressure of contracting muscles on the veins,
forcing the blood toward the heart, 3, the intake of breath (or
aspiration of the thorax) when the auricles are opened to receive
blood, and 4, the valves of the veins which allow the blood to flow
onward but not backward.

The act of aspiration is very closely associated with circulation;
deep breathing alone will promptly quicken the action of the heart
and, consequently, the velocity of the stream.

Variations due to emotion, excitement, etc., — have been al-
luded to. Blood pressure will be considered in Chapter XII.

The total quantity of blood is estimated at about one-twelfth
of the body weight Roughly speaking, it is distributed (in a
state of rest) as follows: — one-quarter in the muscles, one-quarter
in the liver, one-quarter in the heart, lungs, arteries and veins, one-
quarter in other organs. Of course, during the activity of any spe-
cial part of the body, as for example, in the digestive system — the
proportions are changed, as the most active organs require most
blood, leaving less for the others at that time.

CHAPTER XI
THE CIRCULATION OF BLOOD

THE PULMONARY CIRCULATION

This is the circulation of the blood through the lungs, that it
may become aerated or purified.

The pulmonary artery leaves the right ventricle, carrying
impure blood, and soon divides into two branches, the right and
left pulmonary arteries (one for each lung), which break up into a
capillary network around the air cells. From this network veins
arise which, by uniting, form two from each lung, making the four
pulmonary veins carrying purified blood to the left side of the heart.
They enter the left atrium.

THE SYSTEMIC CIRCULATION

This is the circulation of the blood through the entire body or
"system," that it may nourish the tissues and organs (Fig. 126).

Arteries of the Systemic Circulation1

The aorta (Fig. 127), having received pure blood from the lungs,
leaves the left ventricle, arches over the root of the left lung to the
left side of the fourth thoracic vertebra, then (gradually coming
to the front of the spinal column) passes down through the
diaphragm, and ends by dividing at the fourth lumbar vertebra
(a little below the level of the umbilicus). Thus it consists of
three portions: the arch, the thoracic aorta, and the abdominal
aorta.

The arch of the aorta extends from the heart to the body
(lower border) of the fourth thoracic vertebra. It reaches
almost as high as the sternal (or jugular) notch.

It may be felt in thin persons by pressing the finger tip down behind the
bone.

1 The names of all of the arteries are given in tabular form on page 379. Only
the principal ones are here described.

187

i88

ANATOMY AND PHYSIOLOGY

FIG. 126. — SCHEME OF SYSTEMIC CIRCULATION.
Arteries colored red; veins,9blue.

ARTERIES AND VEINS

189

RIGHT COMMON-
CAROTID

Jugular vein

Right lymph-
atic duct

A. ANONYMA

Nerves and

Superior vena
cava

LEFT COMMON
CAROTID

Vagus nerve

Thoracic duct
L. V. anonyma

Branches of

abdominal
aorta

• FIG. 127.— THE AORTA, SHOWING THE THREE PORTIONS.— (Morris.)

ANATOMY AND PHYSIOLOGY

Branches oj the arch in their order:

Two coronary (right and left), .to heart muscle (Fig. 119).

[ Right subclavian to right

upper extremity.

One anonyma, i£ inches long -r>. , ,., .

Right common carotid to

right head and neck.

One left common carotid .... to left head and neck.
One left subclavian ...... to left upper extremity.

Phrenic nerve

Subclavian artery

Subclavian vein

Anterior intercostal
branch

Branch of mammary

Common carotid

Internal jugular vein
Subclavian vein
Scalenus anterior muscle

Sternum

Perforating branches
(supplying mam-
mary gland)

Superior epigastric, running
down from internal mammary

Inferior epigastric, running
up from external iliac

FIG. 128. — SHOWING SDBCLAVIAN ARTERY AND TWO OP ITS BRANCHES
(Thyroid axis and internal mammary). — (Morris.)

THE PRINCIPAL ARTERIES OF THE UPPER EXTREMITY

The subclavian artery (Fig. 128) passes out over the first rib
and under the clavicula (therefore subclavian) to the axilla, or
armpit. The brachial plexus lies above it in the neck, and the

AXILLARY ARTERY

191

subclavian vein is in front of it. The right subclavian is a branch
of the anonyma. Both subclavians end at the lower border of the
first rib.

Branches. — The vertebral branch runs upward through trans-
verse processes of the vertebrae to the brain.

The internal mammary branch runs downward inside the chest
behind the costal cartilages in to the abdominal wall. It distributes
branches to the mammary gland and to intercostal muscles.

FIG. 129. — SUBCLAVIAN AND AXILLARY ARTERiES.-*-(r«/«/.)

The thyroid axis is a short trunk; it gives a branch to the thy-
roid gland and others to the neck and shoulder.

An axis (artery) is a short vessel dividing at once into two or three.

The axillary artery (Fig. 129) is a continuation of the sub-
clavian. It begins, therefore, where the subclavian ends — in the
apex of the axilla, at the lower border of the first rib — and con-
tinues through the axillary space.1

1 Axillary space, p. 368.

IQ2

ANATOMY AND PHYSIOLOGY

Branches (thoracic, subscapular, circumflex.} — To all structures
around the axilla. One, the lateral thoracic, gives arteries to the
mammary gland.

The brachial artery (Figs. 129, 131) begins where the axillary
ends, at the lower border of the axilla, or armpit, and extends

FIG. 130. — DEEP PALMAR ARCH.

Made by continuation of the radial artery. This is covered by the muscles of the
thenar and hypothenar eminences.

downward in front of the arm (with the biceps muscle) to the bend
of the elbow, where it divides into the radial and the ulnar arteries.
Its branches supply the muscles of the humerus and the bone
itself. (The median nerve lies next to this artery under the border
of the biceps muscle.)

RADIAL AND ULNAR ARTERIES

193

Axillary artery

Lateral cord

Pectoral

muscle

Median nerve
Brachia! artery

The radial and the ulnar arteries pass downward in the radial
and ulnar sides of the fore-
arm to the hands. The radial
supplies the muscles in front
of the radius, and winds to
the back of the wrist to find
its way to the palm by pass-
ing forward between the first
two metacarpal bones. It
forms the deep palmar arch,
which crosses the palm under
the long tendons (Fig. 130).

The ulnar supplies the
muscles in front of the ulna,
and forms the superficial pal-
mar arch, which crosses over
the long tendons in the palm
Fig. 131)-

Note. — The superficial arch
crosses the palm opposite the
level of the web of the thumb
when put "on the stretch." The
deep arch crosses about a finger-
width nearer the wrist.

The digital arteries run in the
sides of the fingers; they are
branches of the superficial arch.

Clinical note. — The pulsation
of the radial artery is easily felt
above the wrist in front, next to
the tendon of the radial flexor of
the wrist.

Surgical note. — A direct com-
munication exists between the
deep and superficial arches con-
sequently severe hemorrhage
easily occurs in the palm, since
blood will flow from radial and
ulnar arteries at one and the same
time, and it is sometimes neces-
sary to ligate both.

.Ulnar nerve and

artery

adial nerve and
artery

Branches to hand

FIG. 131. — AXILLARY, BRACHIAL, RADIAL AND
ULNAR ARTERIES. SUPERFICIAL ARCH.

194

ANATOMY AND PHYSIOLOGY

PRINCIPAL ARTERIES OF THE HEAD AND NECK

The common carotid arteries. — (Fig. 127). The right is a
branch of the anonyma; the left is directly from the arch of the
aorta. They proceed upward on either side of the trachea, with
the internal jugular vein on the lateral side and the vagus nerve
behind them. They carry the blood supply of the head and neck.

The common carotid divides at the upper border of the thyroid
cartilage into internal carotid for the interior of the head, and
external carotid for the exterior of the head and the neck.

FIG. 132. — ARTERIES OF THE BRAIN. — (Morris).
Cerebral arteries pass from the base of the brain to all parts of the surface.

The internal carotid is deep in the neck; it runs up to the
head and through the carotid canal into the cranial cavity.

Principal branches. — Ophthalmic, to eye and appendages, nose,
and forehead. (The supraorbital artery is a branch of the
ophthalmic.)

Middle cerebral to the brain, anterior cerebral to the brain
(Fig. 132).

PRINCIPAL ARTERIES OF THE HEAD 195

Note. — The internal carotid makes four sharp turns after entering the
carotid canal in the petrous bone, and by this means the force of the current
in this large vessel is modified before it reaches the delicate tissues of the
brain. The internal jugular vein and vagus nerve accompany it in the neck.

The external carotid artery supplies the face, and front of the
neck and scalp (Fig. 133).

Principal branches. — Superior thyroid, to the thyroid gland
and larynx. Lingual, to the tongue and tonsil. Facial (or external
maxillary) to the face, soft palate and tonsil. Occipital, to the
back of the head and neck.

FIG. 133. — FACIAL, TEMPORAL AND OCCIPITAL ARTERIES.

Clinical notes. — The external maxillary (facial) artery runs toward the
bridge of the nose. It sends two labial arteries to the borders of the lips;
the one in the upper lip supplies a branch to the septum of the nose, therefore,
compression of the upper lip will sometimes stop "nose-bleed."

The lingual artery ends at the tip of the tongue, in a branch (ranine) which
might be severed in cutting too freely for "tongue-tie."

Having given off its branches, the external carotid passes into
the substance of the parotid gland and divides into the temporal
and internal maxillary.

The temporal passes through the parotid gland and across the
zygoma to the side of the head, supplying temporal branches to the
scalp. The internal maxillary runs between the muscles of mas-
tication (in the infratemporal fossa) to the deep parts of the face,
including the nose and pharynx. The dental arteries are all de-
rived from this vessel.

196 ANATOMY AND PHYSIOLOGY

Collateral Circulation. — An important descending branch of the occipital
artery runs down under the deep muscles of the neck to unite with one de-
rived from a branch of the subclavian, thus making a short route between the
subclavian and the external carotid; the blood can flow in this indirect way
to the head if the external carotid be ligated.

PRINCIPAL ARTERIES OF THE TRUNK

The thoracic aorta extends from the fourth dorsal vertebra
to the diaphragm (Fig. 135).

Branches. — Intercostal, n pairs, to the intercostal spaces;
bronchial to lung tissues;1 pericardial to pericardium; esophageal
to esophagus, and mediastinal to glands and tissues between the
lungs (in the mediastinum, p. 365).

Note.-— These aortic intercostal arteries run rather more than half way to
the front, in grooves under the borders of the ribs, accompanied by inter-
costal nerves and veins to meet intercostal branches of the internal mammary

The abdominal aorta extends from the opening in the dia-
phragm to the body (lower border) of the fourth lumbar vertebra —
a little above the level of the umbilicus (Fig. 134).

Branches.— Phrenic to the diaphragm and lumbar (4 pairs) to
the abdominal wall, sacral to sacrum and rectum.

Branches to viscera: The celiac artery, dividing into gastric, for
the stomach; hepatic, for the liver;2 splenic (or lienaT), for the
spleen.

Superior mesenteric, to the small intestine and these parts of
the large intestine, namely — cecum, ascending colon, transverse
colon.

Inferior mesenteric, to the remainder of the large intestine,
namely — descending colon, sigmoid colon, rectum.

Two renal arteries, to the kidneys.

Adrenal arteries, to the adrenal bodies.

The ovarian arteries, to the ovaries, or the spermatic arteries to
the testes.

1 Bronchial arteries have very little to do with respiration; they are the nutrient
arteries of the lungs.

* The hepatic circulation is a double one: Both venous and arterial blood enter
the liver. The portal vein (with products of digestion for the liver to work over) and
the hepatic artery (with the oxygen with which this work is to be done) enter together
through the portal fissure. (The venous blood of both leaves the liver by hepatic
veins, page 209.)

ABDOMINAL AORTA

197

The ovarian artery runs downward into the pelvis and passes
between the layers of the broad ligament to the ovary (p. 201),
freely supplying it and the Fallopian tubes. It ends by anasto-
mosing with the uterine artery (Figs. 134, 138).

Cystic artery

Hepatic duct

Cystic duct

Common duct

Portal vein

rastro-duodenal branch —
uperior pyloric branch —
Hepatic artery

Right suprarenal vein

aferior suprarenal artery

Renal artery

Renal vein

Inferior vena cava
Kidney

Right spermatic vein

Right spermatic artery
Quadratus lumborum

muscle

Light lumbar artery and
left lumbar vein
Ureteric branch of
spermatic artery

Middle sacral vessels

Left lobe of liver

Esophagus ,cut
Left phrenic artery

Right phrenic artery
Superior sui rarenal
Gastric artery
Inferior suprarenal
Splenic artery

Left phrenic vein
Left suprarenal vein
Superior mesenteric
artery

Kidney

Ureteric branch of rena

Left spermatic vein

Ureter

Left spermatic or
ovarian artery

Inferior mesenteric arter
Ureteric branch of
spermatic

Ureteric branch of
common iliac

Common iliac artery

External iliac artery
'Hypogastric

FIG. 134. — BRANCHES OF THE ABDOMINAL AORTA. — (Morris.)
Note that the rig hi common iliac is longer than the left.

The spermatic artery runs downward and along the brim of the
pelvis to pass out through the inguinal canal with the spermatic
cord; it continues downward in the scrotum to supply the testes.

Special notes. — The superior mesenteric lies between the layers of the
mesentery. The inferior mesenteric lies partly in the left meso-colon; it

198

ANATOMY AND PHYSIOLOGY

terminates as the superior hemorrhoidal in the upper part of the rectum
(Fig. 137).

The gastric artery follows the lesser curve of the stomach, and is frequently
called the coronary artery. The hepatic and splenic both send large branches
to the greater curve of the stomach, and also to the'pancreas and duodenum
before reaching the liver and spleen.

Superior vena
cava

V. azygos major

Veins •

Inferior vena
cava

FIG. 135. — COURSE OF THORACIC AND ABDOMINAL AORTA. — (Morris.)

The abdominal aorta divides (bifurcates) at the lower border of
the fourth lumbar vertebra into the right common iliac and the left
common iliac (Fig. 134).

The two common iliac arteries diverge and when they reach
the sides (right and left) of the lumbo-sacral joint, each divides into
hypogastric (or internal iliac) and external iliac (see Fig. 134).

The hypogastric artery passes into the pelvis and gives off

PELVIC ARTERIES

199

branches which supply the parts within and without the pelvic
wall, including the perineum, and all of the pelvic viscera except
the ovaries. (Branches to the exterior of the pelvis pass through
the sciatic and obturator foramin.)

Visceral branches. — Middle hemorrhoidal, to the rectum.

Vesical (two) to the bladder.

Mesenteric
vein

Cedum

Appendix

FIG. 136. — SUPERIOR MESENTERIC ARTERY AND VEIN. — (Morris.)
Supplying the whole of the small intestine, and about one-half of the large intestine.

Uterine to the uterus.
Vaginal (several) to the vagina.

The uterine artery (Fig. 138) passes between the layers of the
broad ligament to the cervix of the uterus, then runs upward along

200

ANATOMY AND PHYSIOLOGY

the side of the body, supplying it freely with blood, and anastomos-
ing with the ovarian artery.

The arteries of the organs in the lower part of the pelvis are
numerous. There are: three (or four) vaginal arteries, three (or
more) vesical arteries, three or more hemorrhoidal arteries, all
derived from the hypogastric or its branches, except the superior
hemorrhoidal which is the terminal portion of the inferior mesenteric.

Aorta

Inferior vena
cava

Right iliac
artery

Middle sacral

Colic artery

Inferior
mesenteric
vessels

Hiac vein
Sigmoid vessels

Superior
hemorrhoidal

Rectum

FIG. 137. — INFERIOR MESENTERIC ARTERY. — (Morris.)
Supplying a portion large intestine only, ending as hemorrhoidal.

There are also two perineal arteries.

These all anastomose freely with each other and with other
arteries, so that a wound in this region is followed by an abundant
flow of blood from more than one vessel.

Note. — The hypogastric arteries in the fetus are large. After
giving off their branches they turn upward to the umbilicus where

EXTERNAL ILIAC ARTERY

201

they leave the body of the child, and become the two umbilical
arteries twining around the umbilical vein in the umbilical cord.
After birth, these portions of the vessels no longer transmit blood
but dwindle to fibrous cords lying close to the anterior abdominal
wall (p. 356).

Uterine Branch to round Fimbriated extremity of

branch ligament Fallopian tube

Uterine artery
.Hypogastric artery

Vaginal arteries

Azygos artery of vagina

FIG. 138. — UTERINE AND OVARIAN ARTERIES.

Uterine, a branch of hypogastric; ovarian, a branch of aorta. Note the location
of the ureter. — (Morris.)

PRINCIPAL ARTERIES OF THE LOWER EXTREMITY

The external iliac distributes its branches almost entirely to
the lower extremity. It is about four inches long and follows the
brim of the pelvis to the inguinal ligament where it becomes
femoral.

Collateral circulation. — The inferior epigastric branch of the external iliac
anastomoses with the superior epigastric branch of the internal mammary, in
the substance of the rectus muscle, thus making an indirect route from the
arch of the aorta to the iliac vessels if the abdominal aorta or iliac artery be
ligated.

202

ANATOMY AND PHYSIOLOGY

r Gluteal n

Deep

branch

Anterior tibial
nerve

[Anterior tibial
artery

Sciatic n.

• Popliteal artery
. Tibial n.

Peroneal n.

, — . Ant. tib. artery

Tibial n.
— Post. tib. artery

FIG. 139. — THE FEMORAL ARTERY. FIG. 140. — THE POPLITEAL ARTERY.

THE VEINS 203

The femoral artery (Fig. 139) is a continuation of the external
iliac, passing through the femoral trigone and the adductor canal to
the popliteal space,1 where it becomes the popliteal artery. Its
branches supply the skin and fascia of the lower abdomen and
external genital organs, and all structures of the front and sides
of the thigh. The largest branch is called the deep femoral,
which lies close to the medial side of the femur and gives three
perforating branches to pass through the adductor magnus muscle
and supply the back of the thigh.

Note. — The femoral vein is on the medial side of the femoral
artery until it reaches the popliteal space.

The popliteal artery is a continuation of the femoral, beginning
at the end of the adductor canal (the opening in the adductor
magnus) and running through the popliteal space. Its branches
supply the boundaries and floor of the space and the knee-joint;
it divides into anterior and posterior tibial arteries (Fig. 140).

The anterior tibial (Fig. 139) comes forward between the
tibia and fibula, supplying the front of the leg; it then becomes
the dorsalis pedis (upon the dorsum of the foot), ending between
the first and second toes. The anterior tibial passes in front of
the ankle-joint, with the long tendons of the toe muscles.

The posterior tibial (Fig. 140) supplies the back of the leg and
sole of the foot. It lies between the calf muscles and the deep
muscles, and runs behind the medial malleolus, dividing then into
medial and lateral plantar arteries for the medial and lateral por-
tions of the sole, or plantar region (Fig. 141).

The Veins

All veins2 run toward the heart.

Beginning as very small vessels formed by the union of capil-
laries, they unite and reunite until they make two sets of larger
vessels called the deep and superficial veins.

The deep veins accompany arteries, being enclosed in the same
sheath with them, and receiving veins corresponding to the
branches of these arteries. Arteries of medium size usually have

1 See p. 371, Popliteal Space.

1 The names of all of the veins are given in tabular form on page 370. Only the
principal ones are here described.

204

ANATOMY AND PHYSIOLOGY

two companion veins (or venae comites) ; large ones have but one,
and it sometimes bears a name differing from that of the artery.
(Example — internal carotid artery, internal jugular vein.)

The superficial veins do not usually accompany arteries.
They lie in the superficial fascia, gathering blood from skin and
fascia, and many of them are called cutaneous. Very frequently
the deep and superficial veins communicate, through short con-
necting branches.

PRINCIPAL VEINS OF THE HEAD AND NECK

Deep. — From the deep face and cranial cavity; they empty
into the internal jugular vein (Figs. 127, 145).

The internal jugular is a continuation of
the transverse sinus (a venous channel inside
the skull, which ends at the jugular fora-
men). This vein lies on the lateral side of
the internal carotid artery in the upper part
of the neck, and further down at the side of
the common carotid artery, with the vagus
nerve between and behind them. (Fig. 127.)
It ends by uniting with the subclavian vein.
Superficial. — From the scalp, ear, and
face, bearing the names of the arteries (usu-
ally) ; they empty into the external jugular
vein which opens into the subclavian.

There are many veins in the spongy bone be-
tween the compact layers of cranial bones, and these
communicate by emissary veins with the sinuses and
also with the scalp veins.

FIG. 141. — DEEP AR-
TERIES IN SOLE OF
FOOT.

i, Medial plantar;
2, lateral plantar. —
(Holden.)

PRINCIPAL VEINS OF THE UPPER EXTREMITY

Deep. — From the hand and wrist; they
form ulnar and radial veins (running with
arteries of the same name) which unite to form brachial veins.

The brachial veins in turn unite to form the axillary, and the
axillary becomes subclavian (Fig. 126).

SUPERFICIAL VEINS

205

Ulnar
vein

Lymph
nodes

FIG. 142. — SUPERFICIAL VEINS,
UPPER EXTREMITY.

FIG. 143. — SUPERFICIAL VEINS,
LOWER EXTREMITY.

206

ANATOMY AND PHYSIOLOGY

Lymph
nodes

The external jugular vein empties into the subclavian at about the middle
of the clavicula. It is easily seen through the platysma muscle.

Superficial. — From fore arm;
groups of veins, both anterior and
posterior, form two, called the basilic
and cephalic, which empty into the
axillary vein.

Median veins in front of the elbow con-
nect the basilic and the cephalic (Fig. 142).

The subclavian, having gathered
blood from the entire upper extrem-
ity, unites with the internal jugular
to form the anonyma vein; the an-
onyma veins (right and left) unite to
form the superior vena cava (Fig.
127).

The left anonyma vein is the
longer of the two, since it must
cross to the right side to join the
right vein.

The Superior Vena Cava

The superior vena cava is formed
by the union of the two anonyma
veins. It lies on the right side of
the arch of the aorta, and opens into
the right atrium of the heart
(Fig. 126).

Great

or long

saphena

vein

VEINS OF THE THORAX
Blood from all of the intercostal
veins (except in the first space)
finally reaches the great azygos vein,
which opens into the superior vena
cava (Fig. 135, azygos major).

The blood of the heart itself is
returned directly to the right atrium
by a coronary vein called the coronary
sinus. All other thoracic organs return their blood to azygos
veins and these to superior vena cava.

FIG. 144. — SUPERFICIAL VEINS,
ANTERIOR.

VEINS OF LOWER EXTREMITY

207

SUMMARY

The venous blood from all structures above the diaphragm
(except the heart) is returned through the superior vena cava to
the right heart (right atrium).

Deep. — From the dorsum of the foot the
veins form the anterior tibial veins; from the
sole of the foot, the posterior tibial.

The tibial veins run upward in the leg
and unite to form the popliteal, which con-
tinues as the femoral, and these two veins
receive others corresponding in name to
the branches of the arteries which they
accompany.

Superficial. — From the lateral part of
the foot and leg, by the small saphena vein,
to the popliteal (Fig. 143).

From the dorsum and medial part of
the foot and leg by the great saphena vein
to the femoral, passing through the oval
fossa in the fascia lata, below the inguinal
ligament (Fig. 144). The femoral vein
becomes external iliac.

VEINS OF THE PELVIS AND ABDOMEN FIG. 145. — SHOWING

FORMATION OF THE LARGE
The veins of the pelvic organs are VEINS.

lo» *A r, i» Superior vena cava; 2,

large and numerous. 3> in^0 Jnate veins; 4, right

In the vaginal walls and around the subclavian; 5, 6, int. and ext.
, , r ,, . , . , jugular veins; 8, inferior

lower end of the vagina, also in the rec- Vena cava; 14, common iliac

turn especially, they form close networks veins- <R.emai?ins Fffer:
* ' ' ences not given.). — (Holden.)

or plexuses which when wounded bleed

profusely. The veins of the anal canal are prone to become con-
gested and assume a varicose condition constituting hemorrhoids.
The pelvic veins empty into the hypogastric, and the hypo-
gastric and external iliac veins unite to form the common iliac.

208 ANATOMY AND PHYSIOLOGY

The right and left common iliac veins unite to form the
inferior vena cava (Fig. 134).

The Inferior Vena Cava

This is formed by the union of the two common iliac veins at
the right side of the bifurcation of the abdominal aorta (p. 197)

FIG. 146. — SCHEME OP FORMATION OF PORTAL VEIN, BY VEINS FROM SPLEEN
STOMACH AND INTESTINES.

(level of the lower border of the fourth lumbar vertebra). It runs
upward through the abdomen, on the right side of the aorta,

PORTAL CIRCULATION

20Q

close to the spinal column, to pass through the diaphragm and
enter the pericardium and right atrium of the heart.

From the abdominal walls the phrenic and lumbar veins open
into the inferior vena cava.

From abdominal viscera the renal and adrenal veins open into
the interior vena cava.

The right ovarian and right spermatic veins open into the in-
ferior vena cava; the left ovarian and left spermatic veins open into
the left renal vein which carries their blood to the inferior vena
cava.

The splenic (or lienal), gastric, and mesenteric veins form the
portal vein, which is four inches long and enters the liver at the
transverse fissure or porta (Figs. 112, 146).

THE PORTAL CIRCULATION

This is the circulation of venous blood through the liver. The
portal vein bears the products of digestion from stomach and
intestines; entering the liver at the porta or gate, it divides into
branches which form an extensive network in its substance.

Having been distributed through these fine capillaries, the
blood leaves the liver by the hepatic veins, which open directly
into the inferior vena cava.

Vessels passing through the porta (or
transverse fissure) of the liver:

Entering
Leaving

Hepatic artery.
Portal vein.
Two hepatic ducts.
Lymphatics.

• All of the hepatic veins leave the liver at the back, opening at once into
a larger vein running to the heart (the inferior vena cava). The great
quantity of venous blood which the liver contains gives to it its dark color.

SUMMARY

The venous blood from all structures below the diaphragm
(except upper lumbar walls) is returned through the Inferior
Vena Cava to the heart (right atrium).

THE FETAL CIRCULATION

The fetus is nourished by blood brought from the uterine
(placental) arteries of the mother, through a special vessel called
14

2IO

ANATOMY AND PHYSIOLOGY

the umbilical vein. After circulating in the body of the child
it is returned to the placenta by two special vessels called the
umbilical arteries, branches of the hypogastrics. (They shrink
to fibrous cords after birth, which may be seen on the interior
surface of the abdominal wall.)

During intrauterine life the lungs do not contain air, therefore,
the interchange of oxygen and carbon dioxid in the blood must be
accomplished elsewhere. This also is brought about by means of
the placental vessels.

Opening closed by
tricuspid valve
Foramen ovale

Coronary sinus

Location of Eu-

stachian valve

FIG. 147. — INFANT'S HEART.
Showing interior of right atrium. — (Holden.)

The plan of fetal circulation requires still other special pro-
vision, namely:

The foramen ovale. — An opening in the septum between the
two atria (Fig. 147). It closes after birth.

The Eustachian valve. — A fold of endocardium in the R.
atrium (so placed as to direct the blood from the inferior vena
cava through the foramen ovale). This remains after birth.

The ductus arteriosus. — A short trunk (1/2 inch long) which
connects the pulmonary artery with the arch of the aorta. This
shrinks to a cord after birth.

The course of the blood is as follows: Arterial blood is brought
through the umbilical vein which enters the body at the umbilicus,
runs upward under the liver (giving branches to that organ) and
terminates by opening into the inferior vena cava, just below
the diaphragm. This blood flows at once into the right atrium
of the heart, where it is guided by the Eustachian valve through

THE PLACENTA

211

FIG. 148. — THE FETAL CIRCULATION. — (Morris.)

212 ANATOMY AND PHYSIOLOGY

the foramen ovate into the left atrium; from there it passes into
the left ventriculum and through the aorta, to be distributed.

The greater portion of this current goes to the head and upper
extremities, from which it returns to the right atrium again and
passes down into the right ventriculum; thence into the pulmonary
artery, but not to the lungs (except a very small portion); it is
delivered instead by the ductus arteriosus to the aorta (at a point
where the arch begins to descend, and joins the small current
already there, to supply the trunk and lower extremities.

The greater portion of this blood leaves the fetus before the
lower extremities are reached, by way of the two umbilical arteries,
and returns to the placenta for re-oxygenation ; while that which
does go to the lower extremities is later returned to the inferior
vena cava to be again mixed with blood from the umbilical vein,
on its way to the fetal heart.

The external iliac supplies the lower extremities before and
after birth.

Notes. — The liver is the only organ to receive blood just as it comes from
the mother; the baby's liver is very large. The head and upper extremities
are next supplied, although with a slight admixture of venous blood (which
came through the inferior vena cava); they are well developed. The pelvis
and lower extremities receive but a small supply of venous with a slight
admixture of arterial blood; they are not so well developed.

The placenta. — The placenta is formed in a portion of the lining
membrane of the uterus, by an intricate arrangement of the uterine
vessels of the mother with the umbilical vessels of the fetus. It is
here that the umbilical arteries coming from the fetus end; and
the umbilical vein going to the fetus arises. Here also the inter-
change of gases and of waste and nutritive matter between fetal
and maternal blood is carried on, in blood spaces of the placenta.

The umbilical cord connects the placenta and the fetus. It
comprises the two arteries and the one vein, protected by a gelat-
inous substance or " Wharton's jelly," in which they are embedded.

CHAPTER XII
PHYSIOLOGY OF THE BLOOD

We have learned that the nutritious portions of the food are,
after digestion, poured into the blood and circulated throughout
the body; also that cell action results in waste which is returned to
the blood. Again, that tissue changes are chemical in their nature
and chemical action is accompanied by heat; this is imparted to
the blood, which can in turn convey heat to other parts.

Here, then, are three important functions of the blood :

1. To convey food (including oxygen from the lungs) to the
tissues.1

2. To convey waste (including carbon dioxide) from the tissues.

3. To equalize the body temperature. Add to these:

4. To provide water for dissolving waste substances to be
removed from the body by skin, kidneys, lungs and intestine.

5. To be a medium for transporting internal secretions (page
263).

6. To furnish its own remedy for hemorrhage by bearing the
factors of coagulation. (See page 217.)

(The blood is a source of water supply as well as food supply
for the body.)

The special functions of the blood cells have been outlined,
namely: — The oxygen-bearing property of red cells and the phago-
cytic power of the white.

Any irritation of the tissues is promptly followed by an increase
in the blood and lymph supply of the part, and (if long continued)
crowding of cells in the capillaries. The leucocytes put forth little
prolongations of their substance which penetrate the vessel wall,
and gradually the cells themselves work their way through. This
causes a hardened or indurated condition which will soon disappear if
not excessive, but with severe irritation the process goes on to inflam-
mation (the cells crowding each other to death) and pus results.

It is due to the character of the capillary walls that the blood
cells can migrate into the tissues (diapedesis) . In case of bacterial

1 It must not be forgotten that oxygen plays an important part in tissue changes
— hence the importance of the blood as an oxygen carrier.

213

214 ANATOMY AND PHYSIOLOGY

invasion, the leucocytes surround and absorb the offending organ-
isms, thus protecting the body from the effects of their toxins.
This they are doing continually because we are constantly taking
bacteria of various sorts into our systems. So long as the number
is not too great the phagocytes can take care of them; it is only
when there are too many that they cannot be overcome.

Consisting as it does of a single layer of endothelial cells, the
capillary wall also renders possible the interchange of fluids between
the blood-vessels and the tissues. This interchange is accom-
plished by the physical process of osmosis, which may be defined
as the diffusion of two liquids or solutions through an intervening
membrane.

Simple diffusion is the mixing of two liquids when poured together, to
form a uniform solution.

Filtration is the passing of a liquid through a membrane or other substance
for the purpose of removing some portion.

It is probable that all three processes go on in the tissues.

Clinical note. — Two methods of local treatment of inflammation are based
upon the above-named conditions: (i) preventive; (2) remedial. By the
application of ice to prevent the intensity of hyperemia which leads to
destruction of the tissues, or by application of heat to cause dilation of sur-
face vessels and relieve it. After tissue destruction has actually occurred ice
is no longer useful.

References have been made to the salinity of the blood and normal saline
solution, which is a solution of the same concentration as blood plasma.
Several very important things are conditioned by the normal salinity of the
blood: (i) The integrity of the corpuscles. They as well as plasma contain
substances which give them a certain density. If the plasma were a fluid of
lesser density, its watery portion would invade the corpuscle and injure or
destroy it. If the plasma were of greater density, the water of the corpuscle
would leave it and the cell would shrink. (The " diffusion streams " of osmosis
would be set in motion in the effort to equalize the densities of cell and blood,
the outer portion of cell protoplasm representing a membrane.)

The subject of osmosis is considered on page 170.

Hypodermodysis. — This is the injecting of a watery solution
of certain salines into the fascia under the skin, for the purpose
of adding fluid to the blood, by absorption from the tissue.
From the preceding paragraph one understands why the fluid
injected must be a normal — or physiologic salt solution — that
is, it must be of the same density as the blood plasma. (The
normal salt solution, better — physiologic salt solution, must con-
tain nine-tenths of i per cent, of salines.)

BLOOD TRANSFUSION 215

3. Transfusion of physiologic salt solution, or injecting directly
into a vein. A more serious measure. Here the blood stream is
invaded at once and good or bad effects are caused promptly.
Accuracy is essential, that the injected fluid should be exactly of
the right density and that nothing else whatever should enter the
vein, lest clot formation occur.

Why are saline fluids introduced into the vessels? (i) To
restore volume to the blood and maintain proper tension in the ves-
sels, thus assisting the action of the heart; (2) to secure the tis-
sues from loss of water and injuries due to disturbances in osmotic
pressure; (3) to insure the distribution of normal red cells; (4)
to dilute the poisons which are not eliminated during processes of
disease, as in uremia.

Direct transfusion of blood is accompanied by a special danger
because it is possible that the blood cells of one individual may
act injuriously upon those of another, causing disintegration or
hemolysis of red cells. (See Glossary.)

The blood of the donor (the person who gives it) may be hemolytic to
that of the patient; that is, it will cause hemolysis of the patient's cells.
Still more to be avoided is the situation where the patient's blood isLhemolytic
to that of the donor. Fortunately this accident need no longer occur, since
laboratory tests can be made which will insure the selection of a donor whose
blood will agree with that of the patient.

Blood transfusion is resorted to after severe hemorrhage, also
in certain diseases, as leukemia, in which the red cells are dimin-
ished in number.

Rapidity of heart action does not necessarily move the blood any
faster through the vessels, as the rapid heart is frequently a weak
heart. Also the short cardiac cycle signifies that the diastole is
shortened; the chambers cannot receive as much blood; conse-
quently, less is sent out.

Another effect of the weak and rapid heart is to deprive it of
proper resting time. It wears itself out.

Quite different is the normal acceleration of heart action in the
course of muscular exercise; this really sends the blood more
abundantly through the body. The auricles are well filled, the
ventricles contract forcibly and the cardiac cycle, although short,
is efficient.

Variations in the blood flow are influenced in the vessels by

2l6 ANATOMY AND PHYSIOLOGY

vaso-motor nerves. By vaso-dilators the arterioles are enlarged,
allowing a free passage of blood ; by the vaso-constrictors they are
made smaller, thus cutting down the quantity of blood in a given
area. A certain balance of tone in the blood-vessel system is neces-
sary to proper action of the heart and to the process of osmosis.

The moving blood current exerts a certain amount of pressure
upon the vessel walls; this (in health) is normal blood pressure —
estimated by the experienced touch, but far more accurately by
instruments designed for the purpose, whereby the pressure in an
accessible artery is recorded upon a graduated scale. The instru-
ment is the sphygmomanometer of which there are various designs.

Blood pressure is increased by an increase in the effort of the
heart, or in the resistance in front of it, or in the volume of the
blood. On the other hand, pressure is diminished by diminished
heart force, diminished resistance, diminished volume.

Arterial pressureis illustrated by the force of the stream spurting
from the mouth of a severed artery. In a small vessel this is an in-
terrupted force, giving the appearance of throbbing or beating in the
stream. Venous pressure causes the blood to well up in a wound
rapidly but with a steady flow. Capillary blood simply oozes.

The cause of blood pressure is the resistance in front of the
stream resulting from the constantly diminishing size of the arter-
ies, reacting to the attempt to drive the blood through them.

Clinical note. — In the processes which lead to arterio-sclerosis the middle
coat of the artery is affected, the loss of elasticity being the first element of
failure. Long-continued high pressure is a common cause of arterio-sclerosis
since it calls for increasing action of the muscle and elastic fibers in the
tunica media and at last tires them out. The elasticity of the vessel wall is
gone; it can no longer preserve normal tone; connective tissue thickening
follows and stiffens the artery. Later, a uniform hardness may be caused and
brittleness, of which a common result is rupture and hemorrhage. This may
occur at any place, often in the brain, often in the muscles of the lower
extremities.

Arterio-sclerosis also interferes with the interchange between the blood
and lymph and the normal metabolism in the tissues.

A physiologic or normal high pressure is caused temporarily by
a quickening of the circulation, as in vigorous muscle exercise:
by nervous excitement, as fright, anger, joy, etc.

Pathologic or abnormal high pressure may be caused by poisons,
either swallowed, or retained in the system from tissue waste, as

COAGULATION OF BLQOD

217

in fevers, or renal or thyroid disease. Low pressure is observed in
conditions of depression, or in muscle exhaustion, or after exhaust-
ing illness; in warm surroundings, etc., etc.

Blood pressure is easily influenced by the use of drugs. For
example, nitro-glycerin lowers it by dilating the arterioles; strych-
nia raises it by contracting them; these are familiar examples.
Many more might be cited.

Hemorrhage is the escape of blood in quantity, from an injured
' vessel. Arterial hemorrhage flows in a forcible stream, bright scar-
let in color; if from a small vessel it will be pulsating or intermit-
tent in force; if from a vessel of medium size, the blood will gush
with a sudden spurt which carries to a rather surprising distance.

Venous hemorrhage presents a steady flow of darker hue, rapidly
accumulating in a wound.

Capillary hemorrhage is persistent oozing.

Coagulation of Blood

Blood which is exposed to the air at the usual temperature is
seen to separate into distinct portions — a red, jelly-like mass and a
transparent straw-colored layer which is thinner. The dark mass

FIG. 149. — DIAGRAM TO ILLUSTRATE THE PROCESS OF COAGULATION, i. Fresh
blood, plasma and corpuscles. 2. Coagulating blood (birth of fibrin). 3. Coagu-
lated blood (clot and serum). — (W otter.)

is the coagulum, consisting of fibrin with corpuscles entangled in it.
The fibrin is essential — no fibrin, no coagulation. The straw-col-
ored layer above it is serum, which is plasma bereft of its fibrin and
corpuscles (Fig. 149). This same process may occur at the mouth
of a blood-vessel which has been cut or ruptured, if the stream
be not too forcible, and it is nature's way of stopping the flow.

The serum, or clear, alkaline layer above the clot, contains all
of the constituents of plasma except fibrin and corpuscles.
The proteins, sugars and fats in their various forms, in combina-

218

ANATOMY AND PHYSIOLOGY

tion with substances which were discarded by the tissue cells, are
all represented, dissolved in the water of the serum.

It is serum which is found in the peritoneum, pleura, pericardium and
other serous-membrane cavities, and which fills the raised cuticle when a
blister " draws." Serum is the basis of exudates and indurations. Gases are
absorbed by serum, carbon dioxide chiefly, with a little nitrogen and oxygen.

Fibrin by itself is a colorless, sticky protein substance, fibrous
and elastic. It may be obtained from freshly drawn blood by
whipping it with a glass rod or more quickly with small twigs.
(This leaves a red fluid called defibrinated blood.}

Formation of fibrin. — Fibrin is derived from the fibrinogen of
the blood by the action of an enzyme called thrombin.

Source of thrombin. — It is assumed that something has hap-
pened to so affect the leucocytes and blood plates that they have
liberated* a special enzyme, thrombokinase, which causes the split-
ting off of thrombin from the pro-thrombin of the blood. The rest
follows: — thrombin acts upon fibrinogen, fibrin is formed, the cor-
puscles are entangled, and coagulation is accomplished.

Diagram of change from fluid to coagulated blood.

Cor- | Red Red cells

puscles \ White (and platelets) . White cells
Fluid Thrombokinase

blood I f Prothrom- I- Throm-

bin.

Plasma

Fibrin

Coagu-
lum.

Coagu-
lated
blood.

Prothrom-
bin

Fibrinogin.
. Serum Serum

The formation of thrombin takes place only in the presence of calcium
salts. (Further than this, the salts are not essential to coagulation.)

For these processes to go on it is necessary that some unusual condition
be present. As has been said, normal coagulation takes place upon expos-
ure to the air. In order that the blood may be exposed to the air, the
vein or artery which contains it must be wounded, the blood flowing over
the injured tissues.

So simple a change from the normal condition as this, is evidently
" unusual " enough to cause the liberation of thrombokinase from the leu-
cocytes afld blood plates and appearance of thrombin, and the rougher the
edges of the wound or the more uneven the surface over which the blood
flows, the more rapidly does coagulation take place.

But (we are told) if an artery or vein be opened in a clean cut with a
sharp knife and the blood received in an oiled tube under oil (thus prevent-
ing any possibility of friction), no coagulation follows; while the same blood
poured into an unoiled tube can be made to coagulate rapidly.

CONTROL OF HEMORRHAGE 2 19

The time required for coagulation is a matter of some im-
portance from the clinical standpoint. The average normal co-
agulation time of undisturbed blood is from two to four minutes
for the beginning of the process and seven to eight for its com-
pletion; these figures vary under certain circumstances. If the
blood is received in a cool vessel without disturbance, coagulation
takes place slowly, the corpuscles sink in the plasma, the red cells
(being heavier) falling to the bottom while the white ones form a
reddish gray layer immediately above, or a "buffy coat," as it is
called, so that the clot appears in layers. Blood from inflamed
tissues coagulates after this manner.

Does blood ever coagulate without exposure to the air; that is,
within the vessels of the living body? Yes, in certain abnormal
conditions. If the lining of the vessel wall is diseased or rough-
ened, or injured — as by application of ligatures, or in the presence
^of bacteria, or when a foreign body is floating in the blood stream,
— these all favor coagulation within the vessels. High body
temperature and various chemical substances have a similar effect,
— the presence of oxygen as well, or the admission of air.

If air finds it way into a vessel forming an air embolus, there is danger that
it will induce coagulation uppn reaching the uneven surfaces of the heart if
not before. This is an unusual accident, but a possible one, consequently
great care should be exercised when filling and using a hypodermic syringe.
(The double accident of piercing a vein and injecting air would have to occur
in order to do harm of this sort.)

Arterial blood coagulates more easily than venous. A stationary clot within
a vessel is a thrombus; a moving clot is an embolus. A portion of a thrombus
may be swept off in the stream as an embolus and, lodging at some distant
point, will become a thrombus there.

Clinical note. — Phlebitis is inflammation of a vein. The blood within
the vein coagulates, and the vein feels like a hard cord.

Coagulation does not occur in the blood of the capillaries nor
within perfectly normal vessel walls in health, nor in blood with a
deficiency of calcium salts.

A dot within a blood-vessel resembles the true coagulum but is not
identical with it, being largely composed of platelets with fewer threads of
fibrin. The white clot found in the heart at autopsy is mostly fibrin.

Control of hemorrhage. — Nature's way is by coagulation at
the mouth of the vessel. To favor this, we seek to i. slow the
current: by rest, by elevation of the bleeding part, by compression

220 ANATOMY AND PHYSIOLOGY

of the artery from which the blood comes (as a tourniquet applied
above the wound), by compress and bandage over the wound. 2.
To cause contraction of the vessels: by applying heat — hot water
118 to 1 20 — in a rapid stream if available, otherwise in hot com-
presses, or cold — ice is best; by the use of adrenalin, and possibly
by styptic solutions which cause a coagulum by chemical action.
(Among domestic remedies, vinegar has a reputation.)

For internal hemorrhage, if of the head or upper part of the body
elevate head and shoulders moderately, command rest. If in
the pelvis or lower part of the body, elevate the foot of the bed,
protect from excitement, secure rest. If from the lungs, elevate
shoulders, forbid speaking.

In case of sudden and profuse bleeding, when the vessels are
rapidly emptying themselves, bandage limbs to secure tension
by driving the blood into a smaller area, and to lessen the demand
upon the heart; prepare for hypodermoclysis, saline transfusion
or blood transfusion.

Since capillary blood does not coagulate direct pressure and
time are required for the control of capillary hemorrhage.

Opsonins and the opsonic index. — It is believed that the phago-
cytic action of white cells is regulated by the presence in the blood
of chemical substances (still undescribed) called opsonins, by
which invading bacteria are prepared for absorption and digestion
by the phagocytes. The measure of the power thus residing in the
blood is expressed as the opsonic index. The opsonic index is high
or low, according to the number of bacteria which the opsonins
may assist the cells to dispose of.

There is some reason for thinking that a special opsonin exists
for each kind of bacterium.

In addition to opsonins the blood contains enzymes, also
various antibodies and immune bodies, which either protect the
body from specific infections, or assist in overcoming invasions
which have already occurred (see p. 214). Each separate poison
or bacterium has its own antibody. The so-called internal
secretions are also carried by the blood (p. 263).

CHAPTER XIII
THE LYMPH SYSTEM. LYMPH CIRCULATION

The lymphatic system comprises an extensive arrangement of
lymph vessels or lymphatics, and lymph nodes (or glands) — both deep
and superficial (Fig. 150).

This system pervades the entire body for the circulation of
lymph — a nutritive fluid derived from the blood. It is by this
means that foods which have been absorbed from the digestive
organs and poured into the blood are separated out for the use of
"the tissues and conveyed to them.

Lymph spaces. — Between the cells and collections of cells of
every tissue, except cuticle, hair and nails, are found minute tissue
spaces or lymph spaces, communicating freely with each other.
There are also spaces around the smallest blood-vessels and nerves
(called respectively perivascular and perineural spaces) . These all
communicate with the beginnings of lymph-capillaries (just how,
is disputed).

Lymph capillaries. — These resemble blood capillaries in that
they have but a single coat (of endothelium). They permeate the
tissues in every direction, forming a close network, from which
lymph vessels or lymphatics originate by the uniting of small
channels to form larger ones (as veins originate).

Lymph vessels. — Are delicate and transparent, but have three
flexible coats. (One elastic, two fibre-muscular.) They are pro-
vided with valves, formed by folds of the lining at very short inter-
vals, which give the appearance of beading to the vessels. This
arrangement allows the lymph to flow toward the heart but pre-
vents it from moving in the other direction.

The lymph vessels of the intestines have been called lacteals
because of their milky appearance during the process of digestion,
the whitish color being due to the presence of fat globules trans-
mitted by the lymph capillaries of the villi. This fat-bearing
lymph is called chyle.

222

ANATOMY AND PHYSIOLOGY

Within the tissues of the body the lymph vessels are too small
to be seen by the naked eye, but they unite again and again to
form larger ones (although still very small) which in some places
may be seen entering or leaving glands, until finally two remain —
the right lymphatic duct and the thoracic duct, which have a diameter
of 3 or 4 mm.

FIG. 150. — LYMPHATIC VESSELS AND NODES.
i and 2 are portions of the THORACIC DUCT. — (Sappey.)

Lymph is a transparent watery saline fluid with lymph cor-
puscles floating therein. It contains nutritive substances for the
tissues and waste matters derived from them.

The description of plasma applies very well to lymph, always keeping in
mind that lymph is more watery and carries lymph cells while plasma bears
blood cells; lymph coagulates but slowly and not so firmly, with a pale clot
because of the absence of red cells.

The origin oj lymph is primarily from the blood. The walls of
the blood-capillaries allow a transudation of thin plasma or serum

THORACIC DUCT 2 23

into the tissue spaces, and this is the source of its nutritive principles.
Waste matters are added as the result of the activities of the tissues
themselves; they represent the "tissue waste." This fluid, con-
veyed by lymph-capillaries to lymph-vessels, is carried to lymph
glands, where it gathers the lymph corpuscles which float in it.

Lymph nodes or lymph glands are small round or oval bodies
of a reddish color, varying in size from that of a pin head to a
small bean, and intersecting the lymph vessels in certain regions of
the body. They are numerous in the neck, axilla and groin, also
in the thorax and abdomen.

A lymph gland is invested with a thin but firm capsule (fibro-
muscular) which sends septa or partitions into the interior, to
support the gland substance in small compartments. The gland
(lymphoid or adenoid) substance lies loosely in this capsule and in
the compartments, leaving spaces for the passage of lymph around
the different portions and around the whole. It contains great
numbers of young corpuscles, which are added to the lymph stream
as it washes through the gland, and appear later as the lymphocytes
of the blood.

Lymph is brought to the glands by afferent lymph vessels,
usually several for each gland. After flowing through the various
spaces in and around the gland substance, it leaves by efferent
vessels, which unite to carry the stream on its way toward the
large veins.

A specimen taken from an efferent vessel and examined under the micro-
scope will show a greater number of lymphocytes than one taken from an
afferent vessel.

The largest lymph vessel is called the thoracic duct (p. 189).
It is about 1 8 inches long, having an average diameter of a small
goose-quill. It begins at the second lumbar vertebra, in a little
pouch called the receptacle of the chyle (or receptaculum chyli] and
runs up behind the aorta, through the diaphragm. It then con-
tinues upward through the thorax to the level of the seventh cer-
vical vertebra, where it arches over to open into the left sub-
clavian vein (at the junction with the left internal jugular). Thus
the lymph and chyle join the current of venous blood on its way to
the heart for circulation and distribution.

The right lymphatic duct is a short vessel, a half inch in
length, which opens into the right subclavian vein at the junction

224 ANATOMY AND PHYSIOLOGY

with the right internal jugular. Through this channel lymph
alone joins the venous blood on its way to the heart.

Note. — The cavities of serous membranes, as peritoneum,
pleura, pericardium and others, belong to the system of lymph-
spaces, but of a special kind. They are surrounded by capillaries
which communicate with them by tiny openings in the membrane,
called stomata.

Like the venous blood current, lymph flows toward the heart.
After the lymph vessels are formed and receive their contents
from the tissues, they take a fairly independent course. The
larger glands are found in the neighborhood of veins as a general
rule but not in the same sheath; knowing the situation of the
glands and bearing in mind that the actual lymph stream flows
from the tissues toward the heart, their course is easily traced and
is of interest and importance as a swollen lymph node gives a clue
to the possible location of the cause.

SITUATION OF THE PRINCIPAL GROUPS OF NODES
OR GLANDS

BELOW THE DIAPHRAGM

Lower extremity. — Popliteal, in the popliteal space, inguinal
(important) at the oval fossa and along the inguinal ligament
(Fig. 152).

Pelvis: External and internal iliac, with the external and
internal iliac vessels.

Abdomen: Mesenteric, between the layers of the mesentery
(about 150); lumbar, in front of the aorta and vena cava. These
are numerous.

ABOVE THE DIAPHRAGM

Upper extremity. — Epitrochlear, above the internal epicondyle;
axillary, under the axillary walls, and clavicular, along the sub-
clavian vessels (Fig. 150).

The axillary glands are superficial, under the borders of the muscle
boundaries; and deep around the axillary vessels. These are very important.

Head: Occipital, below the occiput; auricular, behind the ear;
parotid, upon the parotid gland; submaxillary , under the angle of
the jaw (Fig. 150).

NODES OR GLANDS.

225

Lymph-nodefc

Small sapbena
vein

Lymph-
nodes

Lymph-
nodes

FIG. 151 . — THE LYMPHATICS AND
LYMPH-NODES OP THE LOWER EX-
TREMITY, POSTERIOR.

FIG. 152. — THE LYMPHATICS AND
LYMPH-NODES OF THE LOWER EX-
TREMITY, ANTERIOR.

226 ANATOMY AND PHYSIOLOGY

Neck: Superficial cervical, near the external jugular vein;
deep cervical, with the large vessels (carotid arteries and internal
iugular vein.) (Important.)

Thorax: Mediastinal, with the vessels in the mediastinum;1
bronchial, with bronchial tubes and vessels — these are numerous.

Lacteals
Veins

FIG. 153. — LACTEALS AND MESENTERIC GLANDS. — (Morris.)

COURSE OF THE LYMPH STREAM

BELOW THE DIAPHRAGM

Knowing the location of the glands, and remembering that lymph flows
toward the heart, the course of the stream is easily understood.

From the lower extremity up through popliteal, saphenous, and inguinal
glands to the external iliac, and thence to the lumbar glands.

From the buttock and anterior parts of the genital organs to the inguinal,
external iliac, and thence to the lumbar glands.

In the deeper parts of the genital organs to the internal iliac, and thence
to the lumbar glands.

From the pelvic organs or viscera to the internal iliac, and thence to lumbar
glands.

The ovaries, tubes, and fundus of the uterus send their lymph directly to
the lumbar glands, instead of first through the internal iliac.

From the abdomen, lymph from the abdominal walls flows to lumbar
glands (sometimes indirectly), also from the kidneys and adrenals to the
lumbar glands.

1 See page 365, The mediastinum.

LYMPHATICS OF THE MAMMARY GLAND

227

From intestines through mes enteric glands to the thoracic duct; from all
remaining abdominal organs to the thoracic duct (except upper surface of
the liver).

All lymph which flows through lum-
bar glands runs to the thoracic duct, and
through it to the left subclavian vein.

Note. — The lymphatics in the mesen-
tery, coming from the small intestine,
convey not only lymph but chyle also,
which is light in color and gives to them a
milky appearance, therefore their name,
lacleals (Fig. 153).

ABOVE THE DIAPHRAGM, LEFT SIDE

From the left upper extremity through
axillary and subclavian glands to the deep
cervical glands, thence to thoracic duct.

From left head and neck, superficial :
face and scalp, to occipital, submaxillary,
superficial cervical, and then deep cervical
glands. Deep: face, throat and neck, to
deep cervical glands and thence to thoracic
duct.

From the left thorax, walls and vis-
cera (including left half of heart), to
thoracic duct.

ABOVE THE DIAPHRAGM, RIGHT
SIDE

From the right upper extremity
through axillary, subclavian, and deep
cervical glands, to the right lymphatic duct
(p. 228).

From the right head and neck through
occipital, submaxillary, superficial and deep
cervical glands, to right lymphatic duct.

From the right thorax, walls and vis-
cera (including right half of heart), to
right lymphatic duct.

Lymphatics of the mammary

gland. — Most of these empty into FlG- 154-— LYMPHATICS AND NODES

.... OF UPPER EXTREMITY.

superficial and deep axillary glands;

a few pass through the chest wall to mediastinal glands; those

228 ANATOMY AND PHYSIOLOGY

of the nipple and areola of the two sides communicate with each
other.

The right lymphatic duct gathers lymph from the right upper
extremity, right head, neck, thorax and thoracic viscera, and the
upper surface of the liver.

The thoracic duct gathers lymph from all other parts of the
body — that is, the left side above the diaphragm, and all parts
below the diaphragm, except the upper surface of the liver. The
two ducts empty into the two subclavian veins, and thus the lymph
joins the blood current.

The Flow of the Lymph Stream. — This is maintained by the
same forces which are concerned in the flow of blood in the veins —
(i) the aspiration of the thorax; (2) the intermittent pressure and
relaxation of surrounding muscles throughout the body; (3) the
constantly lowering resistance in front of the stream as the vessels
grow larger; (4) probably by the action of muscle-fibers in the walls
of lymph vessels and the assistance of the numerous valves, by
which they hold what they receive, never allowing the stream to
fall back. Add to these general forces the special influence of
the peristaltic movements of the alimentary tract; these must
cause a rhythmic closing and opening of the lymph vessels which
are the most active of any in the body, and in consequence, a large
volume of lymph containing the products of digestion, is set in
motion.

Clinical notes. — Certain conditions of disease in an organ or tissue are
followed by enlargement of the nearest glands which receive lymph from that
part. If the disease be not arrested, the glands next in order will suffer, and
the next, and the next.

Disease of the mammary gland will cause swelling, first, of the superficial
glands under the border of the pectoral muscle, and later of the deep axillary
and clavicular glands. Mediastinal glands are sometimes affected when the
upper portion of the gland is diseased.

Disease of the tonsils will affect the submaxillary and cervical glands.

Disease of the pharynx, the cervical glands.

Disease of the larynx will affect the cervical glands, and may affect the
mediastinal and bronchial glands.

Disease of the upper extremity will cause swelling of the axillary glands.

Disease of the lower extremity will affect the saphenous group and the
inguinal.

EDEMA EFFUSION. 22Q

. Disease of the external genital organs and lower end of vagina will affect the
inguinal glands along the inguinal ligament.

Disease of the neck of the womb (cervix uteri) will affect iliac glands,
while disease of the body of the womb (fundus uteri), or of ovaries or tubes,
will affect lumbar glands.

The transmission of the causes of disease from one organ to another by the
lymphatics is called metastasis; it is often seen to follow a malignant growth.

The lymph itself, as we have seen, is the medium between the
blood and the tissues. It is only through the lymph that the blood
can feed the tissues and receive the products of their metabolism.
The thinness of the capillary wall allows this interchange between
blood plasma and the lymph in the spaces around the vessels.
The one place of exception is in the lungs. There, oxygen from
the air passes directly into the capillary blood and Coz from the
blood, directly into the air of the lungs.

The process of osmosis has already been mentioned, in con-
nection with food absorption and in considering the physiology
of the blood (pages 170 and 214). It is by the forces included
under this name that the nutritive substances circulating in the
blood are delivered to the tissues and wastes are at the same
time removed from them.

Clinical notes. — Edema is an accumulation of lymph in the tissue spaces.
We have seen that an interchange between the blood and lymph capillaries is
continually going on, the blood providing lymph, the tissues receiving* it,
abstracting nutriment and adding waste. This is not all returned to the
capillaries, a portion is left in the spaces to be carried by lymph vessels to
the two lymph ducts which convey it to certain large veins.

Should this balance of interchange be disturbed, the effect is evident at
once. Whether the supply be too abundant or the outflow be obstructed
the same result would follow — the tissues would be overwhelmed with
fluid, causing edema.

Inflammation of serous membranes, if severe, results in the accumulation
of lymph or serum in their cavities — this is an effusion.

Inflammation in the tissues themselves causes a local excess of lymph
derived from the increased quantity of blood or hyperemia, induced by local
irritation. The accumulation of excess lymph constitutes induration or
hardening.

Hyperemia is evident to the eye when near the surface, by
the redness and heat which it causes. The vessels become so
crowded with cells that the blood can move with difficulty. Serum
and corpuscles make their way through the vessel walls and fill

230 ANATOMY AND PHYSIOLOGY

the lymph spaces, which are still more crowded by the lymph with
its corpuscles held back in the hardened tissues. If the invading
microorganisms which have set up all the trouble are not too
numerous, the phagocytes aided by opsonins will dispose of them.
Then they and the entire accumulation in the tissues — remnants of
cells and bacteria, fluids, etc., will be removed by way of the regu-
lar lymph channels as the swelling subsides.

Clinical note. — The nurse becomes very familiar with the treatment of
this condition of induration; for example — by the use of hot douches to
assist the removal of a pelvic "exudate" by improving the circulation in
the region and in this way favoring absorption. (A pelvic exudate is usually
situated in the broad ligaments of the uterus.)

SUMMARY OF FUNCTIONS OF THE LYMPH SYSTEM

By the lymph, to present to the tissues their proper nutriment
and to receive the waste products of their metabolism.

By the lymph spaces, to transmit the nutritive fluid from the
blood to the tissues, and waste matters from the tissues to the blood.

By lymph capillaries and vessels, to convey lymph to the blood
in the large veins.

By lymph nodes or glands, to give origin to lymphocytes, and to
filter out and retain poisonous or injurious substances from the
lymph stream.

CHAPTER XIV

PULMONARY RESPIRATION AND RESPIRATORY
ORGANS

Respiration is the term used to express the interchange of gases
between the blood and the surrounding tissues, the gases being
oxygen and carbon dioxide.

Pulmonary respiration takes place in the capillary system of the
lungs. The interchange is between the blood and the atmosphere,
or external air; hence, the process in the lungs is called external
respiration.

The exchange which takes place in the capillaries of the tissues
elsewhere is, on the other hand, called internal respiration. As this
depends entirely upon the intake of oxygen by the lungs and the
removal of carbon dioxide in the same organs, the use of the word
respiration without qualifying, has come to signify pulmonary or
external respiration, commonly termed breathing.

Inspiration is the act of drawing air into the lungs; expira-
tion is the act of expelling it. An inspiration and an expiration
together constitute a pulmonary respiration.

By air is meant the atmospheric air by which we are surrounded.
It consists principally of the two gases, oxygen and nitrogen, one
hundred parts by weight of air containing a little more than twenty
of oxygen and a little less than eighty of nitrogen, or, in the pro-
portion of one of O to four of N, roughly speaking. It is the
oxygen which is the essential part of inspired air.

The respiratory organs are the nose, pharynx, larynx, trachea,
bronchial tubes, and lungs, with the thorax and its muscles, in-
cluding the diaphragm; and the pulmonary blood-vessels. These
organs constitute the respiratory apparatus and they include the
respiratory tract, which is a series of channels or air-passages at
the termination of which the air comes into contact with the
respiratory epithelium.

The nose. — The external nose is a framework of bone, cartilage
and skin. The dorsum is formed by the meeting of the lateral

231

232

ANATOMY AND PHYSIOLOGY

surfaces in the median line. Each lateral surface terminates below
in the wing of the nose — ala nasi. The alae are flexible and move-
able. The part that is supported by the nasal bones is the bridge
of the nose. The nostrils are the expanded portion; they contain
no bones, but small plates of cartilage instead, which are moved by
little muscles, therefore, they may be expanded or contracted.

Immediately within the margins of the nostrils are the vestibules; each
vestibule terminates within the tip of the nose in a small pouch, the ventricle.
The nostrils and vestibules of the right and left sides are separated by thin
cartilages forming a mobile septum (columna).

JJ

FIG. 155. — NASAL CAVITY AND NASO-PHAEYNX. — (From Leaver's Surgical Anatomy.)
__ b, Superior turbinal; a, superior meatus; c, middle turbinal; s, middle meatus; d,
inferior turbinal; e, inferior meatus; g, i,j, tongue; k, hyoid bone; p, q, r, sphenoid
bone and sphenoidal sinus; /, naso-pharynx; t>, hard palate (floor of nose).
L_ The remaining references are explained in another chapter (p. 136).

Their internal margins are provided with stiff hairs to arrest
particles of foreign substance in the inspired air.

The cavity of the nose is divided into the right and left cavities

THE LARYNX . 233

or fossa by a partition called the septum, the anterior portion of
the septum being formed by the triangular cartilage of the nose,
the remaining portion by bones — the vomer and the vertical
plate of the ethmoid (Fig. 26). The openings upon the face are
the nares (anterior nares) and those at the back (looking into the
nasopharynx) are the choance (posterior nares).

On the lateral wall of each nasal cavity are three turbinated
bones or shells (conchae), and three spaces or passages directly
underneath them, named as follows: the superior meatus (or
passage) beneath the superior concha (or shell) ; the middle meatus
beneath the middle concha; and the inferior meatus beneath the
inferior concha (Fig. 25). The upper part of each fossa is the
olfactory part; all below that is the respiratory part.

Breath is the air from the lungs with all that it contains; breathing, then,
is producing air which has been passing through the lungs.

The nasal cavities and all of the sinuses which communicate
with them are lined with mucous membrane,
which by the mucus on its surface, prevents
the drying effect of the air upon the pas-
sages, arrests foreign particles, and moder-
ates the temperature of the air on its way
to the lungs. As an organ of respiration,
the nose is important because nasal respira-
tion moistens, filters and warms the air we FIG. 156.— CILIATED EPI-
breathe. THELIUM.— (Stirling) .

The mucous membrane of the nasal fossae is called the Schneiderian mem-
brane. It is ciliated in the respiratory part. In the olfactory part the
olfactory cells are found, which receive the impressions leading to the sense of
smell. For the nose as an organ of the sense of smell, and of voice, see
pp. 326 and 345.

THE PHARYNX

The pharynx is the space behind the nose, mouth, and larynx.
Its use is to transmit air from the nose, and food from the mouth.
As an air-passage it is included with the respiratory organs. (The
air passes from the nose through the pharynx to the larynx.)

THE LARYNX

The larynx is situated below the hyoid bone, in front of the
pharynx, and projects slightly forward in the neck. It is con-

234

ANATOMY AND PHYSIOLOGY

structed of fibre-cartilages connected with each other by ligaments
and lined by mucous membrane. The largest fibro-cartilage is the
thyroid, which forms the prominence of the larynx known as
"Adam's apple." Below the thyroid is the cricoid cartilage,
shaped like a seal ring, and placed with the broad part at the
back, where two small pyramid-shaped
cartilages rest upon it; they are the aryte-
noids. These are all connected by gliding
joints. (Other cartilages, very minute,
are not mentioned.)

The epiglottis is a leaf-shaped flexible
cartilage extending upward from the thy-
roid in front, and resting against the base
of the tongue. During swallowing this is
bent backward over the entrance of the
larynx by the action of small muscles, to
allow the food to pass over it into the
esophagus. (For the Larynx, the Organ
of the Voice, see page 344.)

FIG. 157. — INTERIOR OF
LARYNX (LEFT SIDE RE-
MOVED) . — (Sappey) .

2, Epiglottis; 5, so-called
"false vocal cord"; 9, vocal
band; 13, thyroid cartilage;
14, arytenoid cartilage.
The other figures refer to
parts not mentioned in the
text.

THE TRACHEA

The trachea is a flexible tube about
one inch in diameter and four and one-
half inches long, extending downward from the larynx to the
level of the fourth thoracic vertebra. It is fibrous and elastic,
and stiffened with rings of cartilage which are incomplete at the
back; unstriped muscle fibers take their place, constituting the
tracheal muscle.

The tracheal muscle makes the tube soft where the esophagus lies next to
it, and by the action of its fibers varies the size of the trachea.

The trachea divides into two branches called bronchi. The
right bronchus is one inch long; the left is two inches long (it
passes under the arch of the aorta).

The bronchi divide into branches called bronchial tubes which
subdivide again and again until the smallest tubes, called bron-
chioles, are formed. These lead to the spaces called alveoli, and
the air cells clustered about them.

THE LUNGS

235

The bronchi and larger bronchial tubes are like the trachea in structure,
consisting of fibrous and elastic tissue with incomplete rings of cartilage. In
the smaller tubes the rings become irregular plates or discs, and in the bron-
chioles the cartilage is absent altogether. The walls are here very thin and
contain circular muscle fibers (non-striated), the bronchial muscle.

The entire tract from the trachea down to the air cells is lined
with mucous membrane, bearing ciliated epithelium (Fig. 156) as
far as the smallest tubes.

Thyroid cartilage

Cricoid cartilage

Cartilage
rings of trachea

Left bronchus

FIG. 158. — LARYNX, TRACHEA, AND BRONCHI. — (Morris, modified from B our gery.)

The cilia of the air passages are fine hair-like projections from the surface;
they have a waving motion, exerted forcibly in a downward direction.

THE LUNGS

The lungs are two in number, right and left, situated in the
right and left sides of the thorax, occupying the space enclosed
by the ribs (not that portion between the sternum and the spinal
column). They resemble a flattened cone in shape, the apex

236

ANATOMY AND PHYSIOLOGY

extending one inch above the clavicle, the base resting upon the
diaphragm. The right lung is broader and shorter than the other,

but it has three lobes, upper, middle, and
o-wer. The left lung has two lobes.

Note. — The left lung is narrower
than the right and does not cover the
apex of the heart, otherwise it would be
exposed to the motion of the "heart
beat."

The lung substance consists of
branches of the bronchi and their divi-
sions down to the bronchioles, and the
spaces terminating in air-cells. These

_ structures are surrounded by blood-

FIG. 159. — CLUSTERS OP
AIR-CELLS*— (5 olden, from vessels, nerves, and lymphatics, grouped

together in lobules, supported by fine
fibre-elastic tissue and wrapped in pleura.

Each bronchiole terminates in a lobule.

The root of the lung
is composed of the large
bronchial tubes, blood-
vessels, and nerves (Fig.
160).

The bronchial tubes are
the primary divisions of the
bronchi; the blood-vessels
are — first, the bronchial ar-
teries for the nutrition of the
lung substance; second, the
pulmonary arteries which
form a fine network of capil-
laries around the air-cells,
third, the bronchial and pul-
monary veins. They enter
and leave the lung at the
hilum — a depression on the
medial surface.

FIG. 1 60. — THE LUNGS WITH HEART
BETWEEN THEM.

THE PLEURAE

Each lung is covered (except at the root) by a thin transparent
sac of serous membrane called the pleura. One side of this sac is

THE PLEURA

237

closely applied to the lung, forming the pulmonary pleura; the other
side fits as closely to the ribs, forming the costal pleura. Within
the sac is a small quantity of serous fluid (secreted by the endothe-
lium of the pleura), which prevents friction when the ribs move
and the lungs expand or contract.

Although the bony thorax is bounded above by the first rib,
the thoracic cavity extends an inch above the rib on each side,
bounded by an expansion of the costal pleura and lodging the apex
of the lung.

L. phrenic nerve

R. phrenic nerve

1 Vessels

FIG. 161. — THE PLEURAL SACS.

The dotted lines indicate the pleural sacs, with space between the layers.

(Balden.)

Clinical note. — If the pleura becomes inflamed the quantity of fluid
diminishes and the surfaces rub together, causing acute pain and a fine
crackling sound as of friction. This condition is pleuritis or pleurisy.

Resume. — In respiration, or the act of breathing, the inspired
air enters the nasal chambers, passes through the naso-pharynx,
oro-pharynx, larynx, trachea, bronchi, bronchial tubes, and bron-
chioles, to the alveoli and air-cells or air vesicles.

THE PHYSIOLOGY OF THE RESPIRATORY PROCESS

The function of the respiratory apparatus is first, to accom-
plish an interchange in the lungs between the oxygen of the air
and carbon dioxide of the blood, in other words — to bring nutri-
ment to the blood and to remove waste from it.

238 ANATOMY AND PHYSIOLOGY

We have seen how the blood returns from the digestive organs
laden with food which is to be distributed throughout the body,
where the products of digestion are made over in the tissues by a
series of changes in which oxygen plays an essential part. The
source of the oxygen for this purpose is the air we breathe. It
passes through the air vesicles and the capillary walls into the
blood, thence into the lymph spaces and tissue cells.

The gas called carbon dioxide (resulting from tissue action)
is brought by the blood to the lungs; passing through the capillary
walls and the air vesicles, it is exhaled in the breath and thus re-
moved from the body. Consequently, respiration is a process not
only of nutrition but of elimination as well.

This interchange is accomplished in part by the physical process of diffu-
sion of gases. (The epithelium of the air vesicles is thought to have a special
function £o this end, and is called respiratory epithelium.}

By inspiration we take air, with its oxygen, into the lungs; by
expiration we expel it with carbon dioxide, small quantities of
ammonia and organic waste matter, and moisture.

This important process is made possible by the movements of
the thorax as follows:

In inspiration. — The external intercostal muscles elevate the
ribs and spread them apart, increasing the width of the chest;1
the diaphragm contracts, pulling down its central tendon and thus
increasing the depth of the chest; the lungs expand and receive the
in-drawn air. This is the active phase of a respiration.

In expiration. — The ribs fall easily back into place, assisted
by internal intercostals and abdominal muscles; the diaphragm
relaxes, returning to its dome shape, and the air is pressed out.
This is the passive phase of a respiration.

These acts are performed, in health, with regularity, that is,
rhythmically. The number of respirations in a moment varies
from about 40 in the newly born to 18 in the adult. Normal
respiration is slowest when one is lying down or when sleeping.
The rate is increased during physical exercise or by emotion, and
in visceral inflammations, as pneumonia, pleurisy, peritonitis, etc.,
also in fevers generally.

1 The Pectoralis Major and some others assist in deep breathing or forced
inspiration.

RESPIRATION 239

Average respiratory rate at different ages:

At one year 30

" six years 25

" twelve years 20

Soon after this age, the normal proportion between the number
of respirations and the pulse rate, is as one to four.

Nasal breathing is the natural method of introducing air into
the respiratory passages; mouth breathing is obstructed breathing
and unnatural. The obstruction is oftenest found in the naso-
pharynx, due to adenoid growths or hypertrophy of the naso-
pharyngeal tonsil. Enlarged tonsils obstruct the oro-pharynx;
a deflected septum (p. 27) or hypertrophied turbinal bone may
encroach upon the nasal passages. In all of these conditions
mouth breathing is called to the aid of defective nasal breathing.

Nasal breathing favors the development of the air sinuses or
resonance chambers which communicate with the nose. (See
The Voice, p. 344.)

Important note. — Mouth breathing leaves the chambers undeveloped,
the voice has a decidedly nasal quality and, owing to the flattening of the
facial surface of the maxilla (because the antrum is small) the alveolar process
is unduly prominent. (Many bad effects of mouth breathing might be
cited if space and time were available.)

The normal respiratory sound has been well compared to the
rustling of leaves when the gentlest of breezes is blowing through
them.

The tidal volume of air is that which constitutes a respiration
without effort. The air which is added by an effort of inspiration
(or by forced inspiration) is complemental air. That which is
expelled by effort in addition to a normal expiration, is reserve air.
A certain volume always remains in the depths of the cells in order
to prevent their entire collapse— this is called residual air; it is
changed gradually and constantly.

The organs concerned in respiration must be obedient to a con-
trolling nerve center common to them all, in order that they may
act together for the one purpose. This is called the respiratory
center; it is situated in the brain (in the oblongata).

240 ANATOMY AND PHYSIOLOGY

Normal respiration is, as we have seen, a rhythmic process;
that is, the demand for oxygen is met by the act of inspiration;
this demand satisfied, the passive chest walls sink back into posi-
tion and the lungs retract, but only for an instant; another
demand is followed by another inspiration and the passive
expiration, regularly repeated ad infinitum.

What causes the respiratory center to make this demand? It
is believed that the COz in the blood, which is flowing to the lungs
from the heart, is the normal direct excitant of the center. Many
facts in our experience are explained by this theory; e.g., after
several deep breaths the blood is rich in oxygen and one is content
to suspend respiration, but after a few seconds the oxygen is con-
sumed, the blood is charged with COz and the act of inspiration is
at once stimulated.

The -same theory is advanced to explain the cause of the new-
born infant's first inspiration. With the cessation of the blood
stream from the mother, oxygen is lost, COz accumulates and
inspiration follows.

In injancy and youth the rapid tissue changes of the growing
body cause, in the same manner, a higher rate of respiration than
in adult life. So with muscle exercise, which sends the blood
coursing through the body to gather its load of CO2.

Whatever causes rapid circulation causes rapid breathing. This
is the explanation of the increased respirations of fever.

Reflex stimuli of the respiratory center are without number;
the whole sensory apparatus affects it. Exposure to cold (low
temperature of the air) or sudden contact with a cold body, for
example the chill of cold water, causes a gasp or forced inspiration,
which is soon followed by rapid breathing. (The sudden contact
of the baby's body with the surrounding air is probably a power-
ful excitant to the first respiration, perhaps the principal one, and
often has to be aided by cold sprinkling.) Sharp recurring pain,
emotions of pleasure, anger, surprise, etc., all have a similar effect.

Slowing of respiration follows an accumulation of 0; after a
few deep breaths one may refrain from inspiration for a time
(for from 40 seconds upward) according to training, the blood
using the residual air after the O of the tidal and complemental
supply is exhausted.

Warmth disposes to moderate breathing; a sense of physical

RESPIRATION AND BODY HEAT 241

comfort does the same; reflex stimuli are absent, the system is
relaxed and all processes slow down.

• The breathing of normal sleep is slow and regular. Depressing
emotions tend to diminish the frequency and disturb the rhythm of
respiration. (Witness the "long breath" and frequent sighing of
the morbidly depressed person.)

In certain cerebral and other conditions, the respiratory
center seems to be dulled, so that it responds sluggishly or irregu-
larly, as in meningitis and apoplexy •; also in disease of the
myocardium.

Action of Drugs. — Certain drugs are called respiratory stimu-
lants. Among the best known are strychnine and atropine.
Others are respiratory depressants: as opium (in sufficient dose),
ether, chloroform, and many others.

Respiration is one of those involuntary processes in the body
which we may voluntarily regulate. We may, whenever we choose,
modify the rate and depth of respirations, breathing slowly or
rapidly, deeply or superficially at will. We may even cease to
breathe for a time, because the residual air always present will sus-
tain the demand for oxygen temporarily, although soon we lose con-
trol and respiration will proceed with or without any effort of ours.

Respiration contributory to body heat by providing oxygen
for tissue change in all parts of the body.

Muscle tissue is constantly at work; by rapid oxidation the
muscles generate much heat, but only so long as the respiratory
organs keep pace with the demand for rapid breathing.

It is natural to breathe more rapidly as well as more deeply on
a cold day, because a low temperature of the surrounding air
stimulates (reflexly) the various activities of the body to meet the
call for warmth, and the respiratory process must be among the
first to respond. (The subject of body heat is considered in
Chapter XVIII.)

The tissues which are most active require most oxygen. Con-
sequently we can create a demand and obtain a supply by volun-
tary muscle exercise in good air, thus feeding the blood and through
it the viscera where also much heat is generated, and the entire
body, with this most important element for tissue change.

Summary. — Respiration is a nutritive process, an eliminative
process and a contributing source of body heat.

16

242 ANATOMY AND PHYSIOLOGY

SPECIAL MODIFICATIONS OF RESPIRATORY MOVEMENTS

Rapid breathing is called hyperpnea.

Temporary cessation of breathing is called apnea.

Labored breathing is dyspnea.

Dyspnea follows any interference with the interchange of gases
in the lungs. It may be caused by diminishing the entrance of
oxygen, or by increasing the CO2. It is usually due to imperfect
circulation in the pulmonary vessels.

Asphyxia is the condition resulting from a complete cutting
off of oxygen, or an excessive increase of carbon dioxide. It may
be sudden or gradual, but if unrelieved, ends only in death.

The change of color noted in the face of one suffering from
dyspnea, and still more from asphyxia, is due to the accumulation
of carbon dioxide in the blood.

In Cheyne-Stokes breathing, a period of apnea is followed by
respirations which are at first faint and shallow, then gradually
increase in depth and rate until they become either normal or
exaggerated, when they either cease abruptly or decline to another
period of apnea. This may occur many times in succession, but
is seldom constant. It is seen in the sleep of a patient with fatty
heart, sometimes in the sleep of children apparently well; often
in apoplexy.

Stertorous breathing is characterized by a loud snoring sound;
it is unconscious and sometimes labored.

The production of artificial respiration is attempted by imitat-
ing Nature's method. (See p. 238.) By elevating the arms the
thoracic walls are spread, the lungs follow, air is drawn in. De-
pressing the arms against the thorax presses the walls down, the
lungs are compressed, air is expelled. In this manner not only is
the air current set in motion in the lungs, but an additional stimu-
lus is created by the expanding and subsiding of the lung cells.
When expanded they call for expiration to relieve them, and when
collapsed they demand inspiration to fill them. This is a physio-
logic stimulus which is beh'eved to be constantly felt by the lung
tissue in health.

Internal respiration will be studied under Metabolism. Chapter
XVIII.

VENTILATION 243

Ventilation. — The subject of ventilation is a broad one, since
sb many factors enter into the problem of securing it. The rate
at which air should be renewed is influenced by the number of
people in a room, also by the occupations carried on therein, as
can be easily understood. Even in small rooms the quantity of
air may be sufficient, if a constant current of renewal be secured.
The well-known morning "closeness" of the air of a sleeping room
is due to the fact that in the quiet of the night the ordinary air-
currents are not present. It is the lack of oxygen rather than
the excess of carbon dioxide which is felt and which is in reality
the more serious.

Important Note. — The importance of fresh air in sufficient quantity cannot
be over-estimated. One thousand cubic feet of space for each adult (equal
to a room 10 feet in height, length and breadth), renewed about three times
hourly, is not too much.

CHAPTER XV

ELIMINATION. ORGANS OF ELIMINATION.
THE KIDNEYS

Having studied the Digestive, Circulatory and Respiratory
Organs, or organs of nutrition, we will next consider those which are
active in the removal of waste from the system or the Organs of
Elimination. They are the kidneys, skin, liver and lungs, and to a
lesser extent, the intestinal canal,

Of these, the kidneys alone are specially constructed for the
function of elimination only. The skin, although mainly an organ
of excretion (or elimination), has other uses beside (as will be seen
in succeeding pages).

The liver and the lungs are included under this heading — the
liver, because certain waste products are contained in the bile;
the lungs, because they are agents for the removal of carbon .dioxide.
The intestinal tract is the avenue by which the gross waste material
of the food is expelled, and at the same time it is the main avenue of
entrance into the system of nutritive material. Therefore the
lungs, liver, and intestine are found in both lists of organs, nutritive
and eliminative.

THE KIDNEYS

The kidneys (renes) are the most important organs of excretion.
They separate certain waste matters from the blood, in a definite
form for removal from the body; this is their special function.

They are situated for the most part in the posterior lumbar
region, just in front of the quadratus lumborum muscles, extending
from about the tenth rib to within two or three inches from the
crest of the ilium. They are shaped like a bean, about four or
five inches long and one and one-half inches wide, with the concave
border, or hilus, turned toward the spinal column; and they are
imbedded in fat behind the peritoneum. This is the fatty capsule;
outside of it a thin layer of fascia extends across both kidneys,
being attached to the fascia in front of the lumbar muscles and
lumbar spine. It is called the renal fascia.

244

STRUCTURE OF KIDNEY

245

The other abdominal organs are in front of or above and
below the kidneys, so the natural result of this arrangement is
that they are stationary, the only stationary organs in the abdomen,
the others all move in respiration, digestion, defecation, micturi-
tion, parturition.

The kidney is hollow, the cavity within being called the sinus.
It is covered by a fibrous capsule which also lines the sinus.

Left kidney

Left ureter

Right ureter

FIG. 162. — THE KIDNEYS. (Morris.)

Structure. — A kidney is a mass of minute tubes, the uriniferous
tubules lined with epithelial cells, which perform the real work of
the organ. At the beginning of each is a bulb-like enlargement,
indented to form a deep hollow (Bowman's capsule, Fig. 163)
which encloses a tuft of renal capillaries. The capsule and vessels
together constitute a Malpighian or renal corpuscle. As the
tubule leaves the bulb it twists and turns many times and is called
the convoluted tubule. It has a network of blood-vessels around it.
The convoluted tube finally becomes straight, and at last several
straight ones unite to form a collecting tube which opens into the sinus.

Malpighian corpuscles and convoluted tubes occupy most of
the portion of the kidney near the surface, forming the cortex

246

ANATOMY AND PHYSIOLOGY

(or cortical portion). The straight or collecting tubes are grouped
together into pyramids, pointing toward the interior and forming

the medullary portion . The
apex of each pyramid pro-
jects into the sinus, pre-
senting the openings of sev-
eral collecting tubes (Fig.

164).

The cells which line
this system of tubes do the
work of excreting the urine
from substances in the
blood, thus relieving it of
poisonous elements which
would surely cause death
if allowed to remain.

The urine is conducted
from the kidney to the blad-
der through the ureter, a
slender musculo-fibrous
duct about twelve inches

long, the upper end of which is enlarged and called the pelvis of

the kidney. (It occupies the sinus.) It has a thin layer of muscle

fibers and is lined with mucous membrane.

The two ureters extend into the true pelvis

to the base of the bladder, where they

terminate about one inch apart.

The Urinary Bladder is the receptacle

and reservoir for the urine and is situ-
ated in the pelvis just behind the pubic

bones; between them and the rectum in

the male pelvis, between them and the

vagina and uterus in the female pelvis.

It is a non-striated muscular sac, lined

with mucous membrane which lies in ir-
regular folds when the sac is empty, but

becomes smooth when it is filled. It has

a covering of peritoneum above and posteriorly but not in front.
The upper portion of the bladder is the summit or vertex; the

FIG. 163. — SCHEME OF THE RENAL OR
MALPIGHIAN CORPUSCLE.

i. Interlobular artery. 2. Afferent vessel.
3. Efferent vessel. 4. Outer wall. 5. Inner wall.
6. Glomerulus. 7. Neck of tubule. — (Stohr.)

FIG. 164. — SECTION OF
KIDNEY.— (Potter.}

THE URETHRA

247

lower part is the base or fundus. There are three openings in the
bladder wall, two for the entrance of urine and one for expelling it.

The urine enters through the two ureters (Fig. 162) or ducts
of the kidney, which, having reached the pelvis, proceed below
the broad ligaments (Fig. 138), to run forward and enter the base
of the bladder, there discharging the urine.

The opening for the escape of the urine is called the internal

Bladder Uterus

Urethra Vap'nal Anus (rectum distended)
orifice

FIG. 165. — PELVIC ORGANS, FEMALE PELVIS. — (Holder.)
Dotted lines indicate peritoneum.

orifice. It leads into a canal called the urethra which ends at the
external orifice (or meatus}, and through it the urine is expelled
from the body. The internal orifice is guarded by circular muscle
fibers forming a sphincter — the sphincter vesica (sphincter of the
bladder). The part where the internal orifice is located is often
called the neck of the bladder.

The openings of the ureters are about one inch from the internal
orifice, and the same distange apart, thus these three openings
mark the corners of a triangle at the base of the bladder, called
the trigone.

The urethra is a fibro-muscular canal lined with mucous mem-
brane. It begins at the internal orifice of the bladder, ends at the
external orifice or meatus urinarius, and conducts the urine from
the body.

248 ANATOMY AND PHYSIOLOGY

The length of the male urethra is from seven to eight inches.

The female urethra is about one and one-half inches long and
1/4 in wide, but is very distensible. It curves slightly downward
toward the external meatus.

Clinical note. — The catheter should pass a little upward after entering the
urethra (Fig. 165).

A urethral caruncle is an exceedingly painful little tumor
projecting from the urethral mucous membrane. It is a collection
of sensitive blood-vessels and nerves.

When empty the bladder lies entirely in the pelvis, but if it
contains more than eight ounces it begins to rise into the abdo-
men. It has been known to extend as high as the umbilicus.

Surgical notes. — Since the peritoneum covers the vertex and a portion of
the posterior surface only, the bladder may be entered in front through an
incision just above the symphysis pubis without wounding the peritoneum.

Cystitis is inflammation of the bladder.

PHYSIOLOGY OF THE KIDNEYS AND ACCESSORY

ORGANS

This consists in the removal of waste substances from the blood in the
form of urine and expelling it from the body.

The process of excretion in the kidney is one of filtration and secretion.
The kidney has a large blood supply through the renal artery, which enters
at the hilum and divides at once into several branches. The capillaries from
these arteries are very numerous. They enter first the capsule of the Mal-
pighian body as afferent vessels and form a cluster or tuft there (the glomerulus]
from which the water and salts are filtered out and pass into the tubule.
They then leave the capsule as efferent vessels and twist themselves about the
convoluted tubules, whose epithelial cells select (secrete) the organic substances
— urea, uric acid and others. These are washed down, by the watery solution
coming from the capsule, to the collecting tubes of the pyramids and there
discharged into the pelvis of the kidney, as urine; the amount of urine excreted
varies greatly, but in the adult, in health, averages 48 ounces or 3 pints daily;
it is directly affected by the quantity of fluid which the person drinks, the
amount of perspiration formed and in other ways.

Children excrete more than adults in proportion to the body
size, averaging nearly one-half of the adult quantity at the age of
five years. This is probably due to the fact that their dietary
contains more fluid, also their metabolism or tissue change is
more rapidly carried on, creating more waste material proportion-
ately, to be eliminated.

URINE 249

Clinical note. — Renal colic is caused by the attempt to pass a stone or
calculus through the ureter.

Urine is excreted more rapidly in the middle of the day, from one
to two o'clock, and after waking from sleep ; less rapidly between
two and four in the afternoon.

Micturition is the act of expelling the urine from the bladder
(clinically, it is often called urination). The contraction of
certain muscles of the bladder wall opens the sphincter vesica and
the urine escapes through the urethra.1

Although under the control of the will after a preliminary
period of education, micturition is sometimes involuntary, con-
stituting enuresis or urinary incontinence. This may be due to the
presence of irritating substances in the urine which affect the mus-
cles of the bladder, or to too great concentration, or simply to an
excessive quantity of fluid, or to lack of control by the nervous
system — or various causes of a reflex character.

Retention of urine means accumulation in the bladder owing
to inability to expel it. This may be due to one or more of several
causes: lack of muscle tone and feeble contracting power; nervous
contraction (closure) of the sphincter; impaired sensibility of
vesical nerves; loss of spinal nerve control; obstruction at the neck
of the bladder, etc. This inability may be so complete that the
bladder becomes entirely filled and the sphincter can no longer act;
the urine dribbles away and the condition is one of "retention with
overflow" from inability of the bladder to contract.

Suppression of urine means inability of the kidney to act; no
urine is excreted.

Urine is a watery fluid of amber color, somewhat heavier than
water (the normal specific gravity is 1010-1020), with a charac-
teristic odor, and having the temperature of the body at the time
of voiding. Its reaction is normally acid. This is due to the
character of the diet of man, which in most cases contains more
or less of animal food. Certain salts (acid phosphates) derived
from this mixed diet cause the acidity of the urine. It is more
marked in the morning before food is taken. With a diet of
vegetables and cereals the reaction is neutral or, perhaps, alkaline.

The coloring matter is derived from bile pigments; it is deep or

1 All sphincters are opened in this manner — by action of the walls of the cavity
which they guard.

250 ANATOMY AND PHYSIOLOGY

pale, as the urine contains less or more water. The weight is due
to the salts contained, both organic and inorganic (or mineral) and
this also is modified by the amount of water. Both water and salts
vary markedly with the dietary of the individual.

Clinical notes. — The color and odor may both be modified by drugs or by
articles of food. (For example, turpentine causes the odor of violets, while
that imparted by asparagus is well known.) Urine containing blood cells is
smoky in appearance; and every nurse knows what methylene blue will do.

The most important substance to be excreted in the urine is
urea. This represents the absolutely useless material remaining
from protein foods. It is prepared for excretion in the liver. It
is a substance which if allowed to accumulate in the system
becomes a deadly poison, causing death by uremia.

Uric acid is protein waste in another form and smaller quantity.
Phosphates of sodium, potassium and calcium are present normally,
also other mineral salts, sodium chloride (common salt) being the
most abundant.

Water is necessary for the solution of all these solids. This
varies in quantity in many systemic conditions. Increased
activity of the lungs and skin, for example, removes water from
the blood and thus makes the urine scanty but more dense and
very acid.

Two sets of causes affect the quantity of urine: i. those which increase
or diminish blood pressure in the kidney; 2. those which influence the secretory
activity of the cells which line the tubules. Increased blood pressure increases
the flow of water and salts (in the glomeruli) ; toxic substances (organic waste)
stimulate the excretory function of the cells in the tubules.

The importance of the kidneys is shown by the fact that the
daily quantity of urine normally produced, equals the excretion
of the lungs, skin and intestinal tract together.

The average amount of solids in the body (to be excreted)
does not vary greatly, but the quantity of water ingested varies
constantly and the specific gravity changes with the water supply.

The quantity and the specific gravity bear a pretty constant ratio to
each other. As a rule, the abundant urine is light in weight (low specific
gravity). Conversely, the scanty urine is dense and heavy (high specific
gravity). A notable exception is the urine of diabetes mellitns, which is very
abundant and at the same time has high specific gravity, owing it to the
sugar content.

NEPHRITIS, RENAL CASTS 251

Whatever increases blood pressure increases the amount of
urine; many diuretic medicines act in this manner. Muscle
exercise not only increases blood pressure, but stimulates the
secreting cells by the toxic substances which arise normally from
rapid metabolism and are carried to the kidney by the quickened
circulation.

Nervous excitement and hysteria cause an abundant pale urine.
Cold weather and moist air both discourage the activity of the skin
— therefore, they increase the action of the kidneys.

On the other hand, if the system rids itself of water in other
ways, as by excessive perspiration, diaphoretic medicines, hot packs,
etc., the urine will be diminished, but it will have a high specific
gravity.

Clinical notes. — i. The toxic substances which are present in the blood in
fevers are abnormal to the kidney and modify its action so that the urine is
scanty and dense.

2. Nephritis is inflammation of the kidney. In one form (acute
Bright* s disease} it causes a scanty and dense urine; in another and
chronic form an abundant dilute urine. (When waste ceases to
appear we know that the cells are not secreting.)

3. Certain poisons which are swallowed (bichloride of mercury for
example) cause such intense irritation of the cells in the tubules that
they are seriously injured and may be destroyed.

4. Renal casts. (Tube Casts.} — Irritation of the kidney struc-
ture so changes its tissue that plastic material from the blood
exudes into the tubules and is there moulded into their shape,
forming casts. Hyaline casts are transparent (being the simplest
form). Granular casts show a more advanced stage of trouble.
Epithelial casts have epithelial cells added ; urate casts are common
in rheumatism and tonsillitis, etc., etc.

5. Casts signify renal congestion, always; if persistent they
indicate inflammation.

6. Albuminuria, or the presence of albumin in the urine, is also
an evidence of congestion or of disease. It is often temporary,
disappearing with the disappearance of the cause, which may be
fever, the inhalation of ether, the use of alcohol, etc.

7. Albumin is often due to conditions outside of the kidney

252 ANATOMY AND PHYSIOLOGY

tissue. It is seen in anemia (chronic) ; with the presence of pus,
or accompanying the admixture of vaginal discharge.

Important notes. — Specimens for complete urine analysis should
represent the activity of the kidneys during twenty-four hours, as
the composition of the urine varies during exercise and rest, in
fasting or when food is taken, and so forth.

It will often be the duty of the nurse to test the chemical re-
action by the use of litmus paper. Acidity is due to kidney con-
ditions; alkalinity to bladder conditions (usually). (The reaction
is influenced by drugs.)

Polyuria is excessive secretion of urine.

Oliguria is diminished secretion — scanty urine.

Hematuria is the secretion of bloody urine.

Hemoglobinuria is the secretion of urine which contains the
colored portion (hemoglobin) of disintegrated red blood cells.

Glycosuria is the secretion of urine containing grape sugar or
glucose.

ABNORMAL POSITIONS OF THE KIDNEY

A kidney may develop in some unusual location; if it is fixed in
that position it is called a misplaced kidney.

A floating kidney is one which develops in an unusual location
but is not fixed in that position. It then has a covering of peri-
toneum (meso-nephron) like that of other abdominal organs and
moves freely.

A movable kidney is one developed in the proper place, but either
through loss of the fatty capsule, or relaxation of tissues generally,
it moves in its capsule of fascia. It makes excursions upward and
downward following the movements of the diaphragm and may
be palpated. It may become quite displaced and even fixed in the
abnormal position constituting a dislocated kidney.

During development the kidney consists of lobules which later
become fused into a uniform structure; persistence of this lobu-
lated arrangement (infantile kidney} may be observed at autopsy.
This is not important.

Occasionally one kidney may be absent. Sometimes two kid-
neys are fused into one, making an arched or horse-shoe kidney.

CHAPTER XVI

ELIMINATION

THE SKIN

The skin, or integument, is the elastic and protective covering
of the body. It covers the entire exterior surface and is continuous
at the orifices of the body with the mucous membranes of the
interior surfaces. It consists of two layers, a deep one called the

FIG. 166.

Showing the layers of the skin (greatly magnified), with the sweat glands and oil
glands, and a hair in its follicle. (Brubaker.)

corium, also the cutis vera or true skin, or derma, and a superficial
one called the epidermis or cuticle.

The corium or "true skin" (cutis vera) is a vascular, elastic and
sensitive layer, red and soft; resting upon a loose subcutaneous
tissue. Its deep portion is well supplied with vessels and nerves

254

ANATOMY AND PHYSIOLOGY

(tactile cells} supported by a fibrous and elastic network (reticular
layer) which contains non-striated muscle fibers and fat. In this
layer are the blood-vessels, nerves and lymphatics which are
exceedingly numerous.

Tiny projections called papilla rise from this network portion,
many papilla containing special nerve-endings called touch cor-
puscles. They all contain at least a single loop of blood-vessels.
Some contain several loops — these are vascular papilla. They

are arranged in rows form-
ing ridges which are circular
on the front of the finger
tips. It is a remarkable fact
that no two fingers or toes
are alike in this respect, hence
the thumb- or finger-mark is a
means of identification. Its
value is never lost, even in
old age, as these ridges are
permanent.

The papillae constitute a "papil-
lary layer." There are still other
nerve endings in the corium for different sensations. These are nerve
papillae.

The epidermis (or cuticle) completely covers the corium. It
consists of layers of cells of varying character and thickness. The
deeper cells are soft and nucleated, but near the surface they
become flat and dry, until finally they are mere tiny scales. It has
no vessels and scarcely any nerves, consequently it is not sensitive
and does not bleed. It is this which comes away after the action
of a blister.

The color of the skin depends partly upon the blood supply
and more upon pigment or coloring matter, which is deposited in
the deep layers of the epidermis (and the superficial layers of the
derma). The pigment varies in different people and races.

In all races, the color is deeper in exposed portions of the skin
(face and hands), about the arms, axillae, and the areolae of the
mammary glands. It is lighter than elsewhere on the palms
and soles of the colored races. Exposure to heat as well as light
deepens it.

FIG. 167. — TACTILE CELLS FROM SNOUT
OF PIG. a. Tactile cell. m. Tactile disc.
n. Nerve-fiber. — (Stirling.)

CHARACTERISTICS OF SKIN 255

Clinical notes. — The insensitive and bloodless character of the epidermis
or cuticle is plainly demonstrated in the dressing of a blister, when it is
incised to allow the escape of serum which has accumulated between it and
the corium or true skin. Again, the fact of the pigment deposit in the deep
layers of the epidermis is shown when the blister is on the skin of a colored
person; the pigment comes away with the elevated epidermis.

The surface of the epidermis is continually wearing away and new layers
of epithelial cells are exposed, to become dry and scaly, and to be shed in
their turn. It varies in thickness according to the degree of friction, or pres-
sure, or exposure which it encounters. Witness the palms of the hands and
the soles of the feet, the back of the neck and shoulders, the scalp, and — in
contrast — the thin skin of the flexor surfaces of joints, the groins, medial
surfaces of limbs, etc. (It is in these latter locations that inunctions are
given.)

The vascularily of the skin is evident from the free flow of
blood after the slightest cut. There are two special networks
(rete) of capillaries, one just beneath the true skin, and one at
the bases of the papillae.

The elasticity of the skin is demonstrated when a cut is made
through the corium. The edges retract and some effort is required
to bring them together again. The elasticity is due not only to the
elastic fibers in the deep layer of the corium, but to muscle fibers,
small though they be.

The sensibility of the skin is very marked. Nerve-ends exist
in the corium for various sensations, a few fibrils being connected
with the deep layer of the epidermis. (See The Skin as the Organ
of Touch, p. 327.)

The greater portion of the skin is loosely connected to the parts
beneath it by subcutaneous areolar tissue (see p. 5), so that it is
movable. When this contains fat it is called the panniculus
adiposus. There is no fat under the skin of the scrotum, eyelids
or posterior surface of the external ear.

(The skin of the scalp is not very movable, except as the entire
structure is moved by the epicranial muscle.)

The glands of the skin are in the corium; their ducts pass
through the epidermis to open upon the surface. They are of
two kinds — the sebaceous glands and the sweat glands (sudorijerous
glands} .

The sebaceous glands are found in the skin of all parts of the
body except the palms and soles. They are most numerous upon
the face. They produce an oily substance called sebum which

256 ANATOMY AND PHYSIOLOGY

renders the skin soft and pliable. Their ducts open into the de-
pressions (follicles) for the roots of hairs, consequently they pre-
serve the softness and glossiness of the hair.

Ear wax, or cerumen, is secreted by specialized glands in the
auditory canal (ceruminous glands) .

Note. — The vernix caseosa which is found upon the skin of the new-born
child is an accumulation of sebaceous matter which has served to protect the
skin from the effect of long submersion in the amniotic fluid.

The sweat glands (sudoriferous glands} are found in the skin of
the entire body. Each gland consists of a coiled tube embedded
in the corium, with a duct opening upon the surface; these ducts
open upon the ridges made by the rows of papillae. With an
ordinary magnifying glass the droplets of sweat may be seen.

The sweat or perspiration is a thin watery fluid (highly acid,
but saline to the taste), containing a number of substances in solu-
tion, derived from the vessels in the network of the corium. The
most important are salt, phosphates, urea and carbon dioxide.

It is estimated that the 2,000,000 or more glands secrete nearly
a liter of perspiration daily, in health. The process goes on con-
tinually; when the rate of excretion is moderate and uniform we
are not aware of it, because the moisture is removed in various
ways as soon as formed — this is insensible perspiration. When
the removal does not keep pace with the production, the accumu-
lation on the skin becomes sensible perspiration.

APPENDAGES OF THE SKIN

The appendages of the skin are the glands already 'described,
the nails and the hairs.

The nails are hard but elastic structures belonging to the cuti-
cle (being modifications of its epithelium). They give protection
to, and add power and ease in using the digits. The body of the
nail lies upon a bed of corium called the matrix, from which it
grows; if the matrix be destroyed the nail is lost and no new one
will grow in its place. The root of the nail is embedded in a fold of
skin; the white semicircle at the root is called the lunula (little
moon).

Clinical note. — The body of the nail adheres firmly to the true skin.
Much force is required for its removal.

THE HAIRS 257

The hairs also belong to the cuticle. They are distributed
over the greater part of the surface of the body, being conspicuous
on the scalp by their size and length.

A hair consists of a root and a shaft. The bulb or (enlargement
of the) root rests upon a minute hair papilla in the bottom of a
depression called a hair follicle.1 The nerves and blood-vessels do
not run beyond the papilla.

The shaft extends outward from the root, and contains the
pigment which decides the color of the hair.

The main body of the shaft consists of fibrous or cortical sub-
stance. In this is the pigment of dark hairs, but only minute air
spaces in white hairs. In all coarse hairs except those of the scalp,
and in the roots of most hairs, a central pith or medulla exists
within the fibrous substance. The shaft is covered with a cuticle
of flat scales which overlap each other.

The hairs lie obliquely on the skin but may be made to stand
erect by the contraction of a tiny muscle bundle placed at the root
of each one. These are the erectors of the hairs. It is their action
which gives the appearance called "goose-flesh." The softness
and the gloss of hair are due to the oil which is poured into the
follicles by the oil glands.

Note. — The fine hair on the skin of the new-born child is called lanugo.
It begins to grow at about the fifth month of mtra-uterine life, and wears
away soon after birth, although some remains permanently.

The hairs which border the eyelids are called cilia. The hairs
of the eyebrows are supercilia. Those of the nostrils are vibrissa;
of the head, capili', of the beard, barba.

PHYSIOLOGY OF THE SKIN

The skin has a triple function. It is the protective covering of
the body; an organ of excretion and an organ of the special sense
of touch. Also, it aids in regulating body temperature.

As a protective it is mechanical only; the insensitive layers
receiving first the impressions of external forces — heat, cold, blows,
etc., diminish their effects on deeper and sensitive ones.

As an organ of touch it is referred to on page 327.

1 In the case of curly hair the opening of the follicle leads inward in a curved or
spiral direction.

258 ANATOMY AND PHYSIOLOGY

Its most important function is to secrete perspiration. Per-
spiration is a clear watery fluid consisting of a solution of certain
waste products of metabolism (tissue waste), in other words, water
and solids. It is acid in reaction; saline to taste. The quantity
excreted by a healthy active person in twenty-four hours has been
estimated as one quart.

Although the amount of solids in the perspiration is small, it
is enough to relieve the system if the kidneys are disabled, or to
embarrass it if retained. Urea is one of the substances contained
in perspiration, and in diseased conditions of the kidneys the skin
is able to excrete an increased quantity of urea.

The removal of tissue waste is, however, not the only important
use of perspiration. By bringing water to the surface of the skin,
it is a most efficient agent for regulating the temperature of the body.
Muscle exercise, for example, which increases heat production, is
accompanied by increased activity of the sweat glands, and the
consequent evaporation oj water carries off the excess of heat
generated in the muscles. Again, high temperature of the sur-
rounding atmosphere causes dilatation of the cutaneous vessels,
and more perspiration and consequent evaporation. Conversely,
a cold atmosphere stimulates the cutaneous vessels to contract,
and stops the production of sensible perspiration. All of this
activity is, of course, a response to the controlling force of nerve
centers which regulate blood supply, and stimulate secretory
action.

Clinical note. — From these facts one may understand why it is so impor-
tant to conserve the surface temperature of a patient with nephritis, or with
diminution of urine from any cause, by the use of blankets and warm clothing;
and to increase it oftentimes by the use of hot baths, packs, etc.

In health the quantity of perspiration is modified by the die-
tary, particularly by the amount of liquid taken, and the kind of
liquid; also by the character of clothing, the season of the year,
temperature of the atmosphere, etc.

It may be noted that the activities of the skin and kidneys
alternate with change oj season; in summer when the skin is active
the urine is scanty. In winter, when the skin is inactive the urine
is free.

Drugs which increase the production of perspiration are called
diaphoretics. Aconite and sweet spirits of nitre are familiar exam-

ACTIVITIES OF THE SKIM 259

pies. Hot drinks and muscular effort assist diaphoresis. Nervous
excitement, as fear, pain, nausea, produces the same effect. The
toxins of certain diseases also cause excessive perspiration, as in
the nocturnal sweating of tuberculosis, the crisis of pneumonia,
and other instances.

In fevers, cutaneous vessels are dilated, but the nerve stimulus
to cell action is dulled and the skin remains dry.

Some other diseases have a similar effect; loss of water by
colliquative diarrhea (characterized by profuse liquid stools) leaves
the sic in dry. In diabetes mellitus a very troublesome symptom
is dryness of the skin with pruritus or itching (and a tendency of
the connective tissue to break down in boils).

The effect of baths upon the skin is to abstract heat, improve
the tone of cutaneous structures, and favor the action of the glands.

In renal diseases, activity of the skin is to be promoted; in fevers,
activity of the kidneys, as well as of the skin.

The skin has a slight degree of absorbent action in the areas
where it is thinnest; this power is utilized for inunctions.

Clinical note. — The skin should be well rubbed until it is warm and quite
dry of perspiration or oil before applying a medicine by inunction, in order
that the circulation of cutaneous vessels may favor absorption. Animal oils
are more easily absorbed by the skin than vegetable oils.

SUMMARY

The skin is protective, excretory, an organ of special sense, of heat
regulation and — to a moderate extent — of absorption.

CHAPTER XVII
MAMMARY GLANDS. DUCTLESS GLANDS

THE MAMMARY GLANDS

The mammary glands are placed between two layers of super-
ficial fascia in front of the thorax, occupying a space between the
third and sixth ribs, inclusive. They are covered by a layer of adi-
pose tissue and lie between two layers of superficial fascia. They

FIG. 168.
Showing enlarged milk ducts during lactation. — (Morris.)

consist of little tubes, lined with milk-secreting cells and grouped
in small lobules, held together by connective tissue imbedded in
adipose. The lobules unite to form lobes, 18 or 20, each with its
own duct, thereby constituting a complete gland in itself; these
1 8 or 20 milk ducts (lactiferous ducts) approach the nipple and open
at its summit. The nipple is surrounded by a ring of darker
modified skin called the areola. A few small elevations are seen
on the areola; they are called the glands of Montgomery.

260

COMPOSITION OF MILK 261

Frequently, prolongations of mammary tissue extend laterally from the
gland toward the border of the axilla, sometimes they are found near the
sternum.

The function of the mammary gland is the secretion of milk.
This is a true secretion; the cells of the tubules forming a new sub-
stance from materials brought by the blood, which, although not
utilized in the body where it is formed, is not only useful but
capable of sustaining life.

Note. — The presence and activity of the ovaries seem to be essential to
the proper development of the mammary gland.

Milk is a bluish-white fluid consisting of clear plasma (milk
plasma) holding nutritive substances in solution and floating
myriads of oil globules, to which it owes its white color. It is a
natural emulsion. The variety of nutritive substances contained
in it is sufficient for the development of the body of the infant.

Human milk is amphoteric.1

The contained proteins are peculiar to milk and form a soft
. flaky curd in the process of digestion. They are several in number,
the most important being caseinogen, from which casein is derived
in the process of digestion. (Cow's milk forms a tough curd in
digesting. It contains more casein but less sugar and less fat. It
is nearer acid than human milk.)

The sugar of milk is lactose (probably absorbed as such — does
not require digesting). The salts are the various salts found in
foods and the body tissues, the most abundant being compounds
of calcium, potassium and sodium.

The water and salts are derived directly from the blood by
filtration; the special proteins and lactose are secreted by the cells
of the tubules. (Lactose is found nowhere but in milk, the same
is true of lact-albumin — they are special secretions of the mammary
glands.)

Average percentage of fat, sugar and proteins in milk as given
by Holt:

Colostrum Human milk Cow's milk

Fats 2.04 3-5 3.5

Sugar 3. 74 6-7 4-3

Proteids 5.71 1-2.25 4

1 Amphoteric. Neither acid nor alkaline, acting on both red and blue litmus
paper.

262 ANATOMY AND PHYSIOLOGY

During pregnancy the areola acquires a deeper color (which is
permanent) and the glands of Montgomery are enlarged.

At this time the blood supply of the gland increases, the glands
become large, and changes occur in the lining of the tubules, which
result in the secretion of milk. This is perfected soon after the
end of pregnancy.

The first fluid which is drawn from the breast is called colos-
trum; it is yellow (from the presence of colostrum corpuscles),
alkaline, rich in proteins and salts but not in sugar nor in fat. It
contains a substance which acts as a laxative for the infant.

The secretion of milk is influenced by the diet of the mother and
may be modified in both quantity and quality by food selection.
A still greater effect is produced by the condition of her nervous
systems; it is well known that fright or anger, or intense emotion,
may so affect the milk as to make it injurious to the infant.
Fatigue, worry, loss of sleep, etc., are all to be avoided by the
nursing mother.

Human milk contains a small quantity of starch splitting
(amylolytic) enzyme; it is possible, therefore, to exert some effect
upon the starch content of barley water in the food of the young
infant so that some nourishment may be gained from it.

The milk may differ in the two breasts of the same person.

Menstruation is accompanied by a diminution of lactose and
an increase of fat and casein.

The milk of the pregnant woman is poor in quality, especially
in fat.

Clinical note. — Certain drugs taken by the mother will be
eliminated through the milk in sufficient degree to affect the
child; as beer, or bromides, salines and other cathartics; strychnia,
arsenic, etc.

Surgical note. — Mammary abscess is caused by infection
through a break or fissure in the skin of the nipple, the pus form-
ing between the lobes of the gland. Post-mammary abscess is in
the fascia behind the gland.

THE DUCTLESS GLANDS OR THE ENDOCRIN SYSTEM

This system includes the ductless glands and the chromaffin
tissues.

THE PANCREAS 263

These are the organs which resemble glands but have no ducts.
They are supplied with sympathetic nerves, and possess many
lymphatics and blood-vessels; the secretions which they produce
are internal secretions and are carried in these vessels. The most
important ductless glands are the spleen, adrenal bodies and
certain portions of the pancreas, in the abdomen; thyroid, para-
thyroid, and thymus bodies in the neck; pituitary body (or
hypophysis) in the cranial cavity. To these may be added the
ovaries (also the carotid, parasympathetic and coccygeal bodies).

The cells of the chromaffin tissues are found in the interior of
the adrenal bodies and in certain small groups which are ranged
along the abdoninal aorta.

Each of the structures of the endocrin system bears a relation
to one or more of the others which is not yet perfectly understood.

Their secretions have never been obtained for examination
but there is abundant evidence that they exist.

The name autocoid substances has been proposed for the active
agents in these secretions. It is believed that there are two kinds
of autocoid substances: the hormones, which stimulate activity
in tissues to which the blood carries them, and the chalones,
which inhibit or prevent activity where they are carried. Each
member of the endocrin system has its own special autocoid
substance.

So little is understood of the action of these various organs
that descriptions are necessarily brief.

THE PANCREAS

In addition to the digestive ferments of the pancreas it produces
another and highly important substance, which either disposes of
sugar in the blood, or is associated with the glycogenic function of
the liver, or both. This is supposed to be the special function of
groups of cells called "islands of Langerhans" which are embedded
in the substance of the pancreas. They resemble glands but
have no ducts; they are surrounded by a network of capillaries
and their internal secretion is transmitted by these vessels.

The blood supply to the pancreas is very free, being derived
from the hepatic, splenic and superior mesenteric arteries. This
indicates the importance of the gland.

264

ANATOMY AND PHYSIOLOGY

Clinical notes. — Disease of the pancreas is accompanied by the appearance
of an excessive amount of sugar in the urine, or diabetes mellitus of a severe
character.

Removal of pancreas, if complete, causes the same result which, however,
may be prevented by transplantation of a piece of pancreas tissue under the
skin.

THE SPLEEN

It is believed (but not proven) that the cells of the splenic pulp
contain an enzyme which aids in the digestion of protein foods,
through its action upon the pancreas, by furnishing hormones to
stimulate the production of protein-digesting enzymes in the pan-
creatic juice.

THE ADRENAL BODIES

The 'adrenals (suprarenal capsules), are two small gland-like
bodies resting on the upper extremities of the kidneys, hence their
name. They are triangular in shape, yellowish in color, and have
many blood-vessels and nerves. The superficial portion of the
adrenal body is the cortex or cortical portion.
It is this part which is in some way, neces-
sary to life.

The interior portion, enclosed by the
cortex, is the medulla, or medullary por-
tion; this is one of the chroma fin tissues,
and it is thought that the internal secretion
is here formed. The adrenal bodies are
important organs, as it is found that when
they are removed death follows soon, but
their use is not yet fully understood. It
has, however, been determined that the
internal secretion, epinephrin, acts through
sympathetic nerves on plain muscle fibers
and the heart; its effect is to cause contrac-
tion of small arteries, thus increasing blood pressure, at the same
time slowing the rate of the heart beat. Because of this, epinephrin
or adrenalin is an important agent in checking hemorrhage by
local application, as in operations upon the throat or nose.

A solution of epinephrin or adrenalin given by hypodermic in-
jection is used to relax the spasm of bronchiole muscle fiber in

FIG. 169. — THE AD-
BEN AL BODY is SEEN

RESTING UPON THE KlD-

NEY. — (Potter.}

THYROID BODY . 265

asthma. It will also shorten the coagulation time of blood (tem-
porarily). It inhibits contraction of the stomach and intestine,
also of bladder and uterus.

In the disease called "bronzing of the skin," or Addison's
disease, these bodies are found to be changed.

THE THYROID BODY

The thyroid body is situated in the anterior part of the neck
(Fig. 170).

It has two lateral lobes lying close to the upper portion of the
trachea and connected by a middle portion called the isthmus.

Median portion of crico-
thyroid membrane

Crico-thyroid muscle

^ Lateral lobe of thyroid body

^^K

Thyroid isthmus

FIG. 170. — THYROID BODY. — (Morris.)

These lobes are about one and one-fourth inches wide, and extend
about two inches upward along the sides of the larynx. A middle
lobe may exist, extending upward from the isthmus in front of
the larynx.

The substance of the thyroid body is made up of closed sacs
containing a thick semifluid substance (colloid substance). They
are surrounded by many capillaries; the thyroid arteries being
four in number, the blood supply is very free. It is supported in
its position by fibrous attachments to the sides of the larynx and
also to the fascia behind the trachea.

Clinical note. — If the thyroid body becomes very much enlarged it does
not freely glide upward and downward with the larynx in the act of swallow-

266 ANATOMY AND PHYSIOLOGY

ing as, normally, it should do; if it is fixed by adhesions or by excessive
growth it exerts traction upon the larynx and trachea which is visible during
the movements of swallowing.

The function of the thyroid body is important but not well
explained. It is observed that the development of both mind and
body is arrested if the thyroid be absent, or if it does not itself
develop in childhood; this condition is known as cretinism.

Degeneration or complete removal, in adult life, is followed by
excessive growth (but imperfect development) of connective tissue
and skin elements, or myxedema, and a gradual deterioration of
mental power. These effects may be prevented by leaving a
small portion of the gland in place or by transplanting it.

From these and other clinical observations it is evident that
the internal secretion of this body exercises an important influence
upon nutrition. It stimulates cardiac action, increases blood
pressure, and restrains a tendency to obesity.

Clinical notes. — Simple enlargement of the thyroid body constitutes
goiter, which is said to be frequent in certain countries where the drinking
water contains much lime.

Exophthalmic goiter is a diseased condition of the thyroid body with the
following symptoms: Enlargement and pulsation of the thyroid, rapid heart
action, tremor, and protrusion of the eyeballs.

THE PARATHYROID BODIES

The parathyroid bodies are small bodies situated above and
laterally to the thyroid, two on each side. They have an abundant
blood supply. Their function is not explained but it is now known
that their removal is soon followed by convulsive affections,
tremor, etc., suggesting the presence of an irritant in the blood
which did not exist before. Consequently it may be that their
internal secretion is able to neutralize certain toxic substances
formed elsewhere, and capable of causing death.

Both parathyroid and thyroid bodies contain iodin in combina-
tion with some other substance.

THE THYMUS BODY

The thymus body (Fig. 171) is an organ of fetal and infantile
life, situated below the thyroid, being mostly in the thorax and ex-

PITUITARY BODY

267

tending downward to the pericardium. It is two and one-half
inches long at the age of two years, but dwindles slowly from that
time on, leaving very perceptible remnants only, during adult
life. A persistent thymus is one of the features of the condition
known as infantilism. It has been thought that its secretion
lowers blood pressure.

Thyroid

Lung

Liver

Suspensory
ligament

Small intestine

Bladder

Trachea

Thymus

Lung

Right auricle

Right ventricle

Stomach

Part of transverse
colon

Hypogastric
artery

FIG. 171. — VISCERA AT BIRTH. NOTE THE THYMUS BODY, THE SIZE OF THE
LIVER AND THE LOCATION OF THE BLADDER AND THE HYPOGASTRIC ARTERIES. —
(Morris after Rudinger.)

THE PITUITARY BODY

The pituitary body (Fig. 193) (hypophysis cerebri) is included
among ductless glands. It rests in the sella turcica of the sphenoid
bone. By investigation it has been learned th&t degeneration of this
body in the adult is the probable cause of the disease called acro-
megaly, which is characterized by an overgrowth or hypertrophy
of the bones of the face and extremities. Should this occur in
young children or while the bones are still developing, over-growth
of the skeleton or gigantism will result. Certain conclusions have

268 ANATOMY AND PHYSIOLOGY

been founded upon this association, presupposing that it produces
an internal secretion which regulates the growth of bones. It also
increases the force of cardiac action and general blood pressure.
It is found to stimulate the contraction of unstriped muscle fiber,
as in the uterus, and has been used for that purpose. Its influence
upon metabolism is still under investigation. Its removal is fol-
lowed by atrophy of the generative organs.

Clinical note. — Hypertrophy or tumor of the pituitary body
or hypophysis causes blindness by pressure upon optic nerve fibers.

The carotid bodies are placed behind the common carotid artery just at
the point where it bifurcates. Use unknown. The para-sympathetic bodies
one to four in number, lie in front of the third and fourth lumbar vertebrae.
Use unknown. The coccygeal body lies in front of the lowest part of the
coccyx. Use unknown.

CHAPTER XVIII
METABOLISM

We have now studied the various organs which form secretions,
or substances which may be either devoted to a special use in the
body, or expelled as of no further use. These latter are known as
excretions.

SECRETION

Following, is an enumeration by way of review, of the principal
organs whose secretions are used in the body, with a partial list of
their functions:

First. — The epithelial cells of all surface membranes and cavities
should be included:

Those of mucous membranes, secreting mucus.

Those of serous membranes, secreting serum (as in the pleural,
pericardial and peritoneal cavities, and the subdural and sub-
arachnoid spaces of brain and spinal cord).

Those of synovial membranes, secreting synovia.
The secreting cells of glands come next.

The salivary, gastric and intestinal glands and pancreas secrete
saliva, gastric, intestinal and pancreatic juices.

The liver secretes bile (and forms glycogen).

The mammary glands secrete milk.

The lacrimal glands secrete tears.

The sebaceous glands secrete sebum.
Of the secretions of so-called ductless glands, or endocrin system.

That of the pancreas influences glycogen-processes in the liver.

That of the adrenal bodies increases blood pressure (contracting
arterioles) and retards the rate of cardiac action, also favors the
formation of sugar in the body.

That of the thyroid body influences tissue metabolism, increases
cardiac action, and diminishes obesity.

That of the parathyroids destroys toxins in the blood (or
inhibits their formation?).

269

270 ANATOMY AND PHYSIOLOGY

That of the pituitary body (or hypophysis) restrains growth of
osseous tissue and influences metabolism, establishing a tolerance
for sugars.

That of the ovary is associated with the function of the mam-
mary gland and the uterus, and influences the action of vaso-
motor nerves of the systemic circulation. This internal secretion
is furnished by the corpus luteum (p. 349).

In addition to the above may be mentioned:

The spleen and lymph glands which supply white cells to blood.

The marrow of bones which supply red cells to blood.

The testes which produce spermatozoa.

The secretions of the organs named, serve various purposes,
aiding or influencing nutrition, or assisting in the formation of
other substances.

EXCRETION

Excretions. — These are the substances which must be elimi-
nated from the body.

All tissue action uses up some material, leaving a varying rem-
nant of waste matter which cannot be utilized — like the ashes from
a fire. These wastes appear either dissolved in water as urine and
perspiration, or in the form of gas or vapor.

Tissue waste may be reduced ultimately to comparatively few
substances, the most important being urea, carbon dioxide, various
salts and water. Urea is most abundant in urine, COz in exhaled
air, and all of these in small quantity in perspiration.

Therefore, the organs of elimination are:

The kidneys, which excrete urine.

The skin, which excretes perspiration.

The lungs, which exhale carbon dioxide, organic matters, am-
monia and water.

To these may be added the liver and the intestinal canal.

The liver excretes waste matters with the bile and forms urea.

The intestinal canal excretes small quantities of tissue waste
(gases, water, mucus, etc.).

GENERAL METABOLISM

We have studied the framework of the body with its various
connections and adaptations, its coverings and its cavities, the

METABOLIC PROCESSES 271

organs by which it is fed and the wear and tear of its machinery
continually made good, as it is nourished and sustained — a
living organism.

The combined processes of up-building and breaking down — in
the living body — constitute metabolism. A well-equipped labora-
tory presents facilities for illustrating the actual chemical changes
which take place, but only in the living cell are they metabolic.

Attention has been directed to the four classes of substances
composing the body tissues, and the corresponding food-substances
supplied to them in the dietary. We have seen that these foods
are presented to the body in compounds more or less complex (most
of them insoluble) and we have traced (briefly) their changes in the
system from the time of ingestion to their disposition in the
tissues or their expulsion as excreta. It remains to review them
from the standpoint of their value in metabolism.

All foods must subserve one or more of three purposes, namely:
— to evolve heat; to release energy; to repair waste.

Proteins, being reduced by digestion to simpler forms (peptones
and amino-acids) are absorbed and appear reconstructed in muscles,
blood, lymph and milk, mainly (in all tissues actually), where by
their nitrogenous portion they contribute to the "betterment of
cell conditions" and compensate for wear and tear everywhere in
the body; by their non-nitrogenous elements they evolve heat
and create energy.

Protein wastes (or excreta) take the form of urea — uric acid and
compounds — ammonia — excreted through the kidneys.

Carbohydrates, taken as sugar or converted into that form,
are absorbed and circulated, stored in liver and muscle as glycogen
to appear when needed as sugar again— to be oxidized for the pro-
duction of heat and energy or stored as fat. Their excreta are COj
and water.

Fats, after digestion, are distributed for use in many parts,
their oxidations evolving heat and motion, or are stored in sub-
cutaneous fascia, marrow, between viscera, etc. Their excreta
are CO2 and water.

Mineral Salts and water are absorbed together in solution and
distributed to aid in the formation of various tissues throughout
the body.

It thus appears that all foods contribute to body heat and

272 ANATOMY AND PHYSIOLOGY

energy, by entering into the up-building of the tissues which are
quickly used up for those purposes; while the proteins have in addi-
tion as their principal function, the construction of body tissues of a
more permanent character.

These changes are largely dependent upon the combination of
oxygen with food or tissue compounds. "The essential source
of heat and mechanical work developed in the animal organism
is to be found in the oxidations" (Hammarsteri). But behind
these are the enzymes; in nearly all active tissue cells the changes
begin with their action. Certain oxidizing ferments make the
first splitting of complex substances, afterward the union with
oxygen follows.

In digestion processes we have seen that the first change is
associated with a splitting of and union with the elements of water
(H20). • The enzymes which set this change in motion are hydro-
lytic enzymes.

FOOD VALUES

By study and experiment it is found that the proper propor-
tions of proteins, carbohydrates and fats in the human dietary are
as follows: — proteins one-fifth, fats one-fifth, carbohydrates
three-fifths. Since in the body, heat and mechanical work are
produced in company, the degree of heat evolved by work is taken
as the measure of force to be supplied by food, or the measures of
food value.

The heat unit of measurement is called the calorie (large
calorie], which signifies the amount of heat required to raise one
kilo of water to i°C.

A food which when burned will do this has a calorific value of
one degree, that is, it is graded at one calorie in value.

The following are estimated averages of calorific values.

Proteins one gram yields 4 . to 4 . i calories.

Carbohydrates one gram yields 4.1 calories.

Fat one gram yields 9.3 calories.

The average working man of 20 kilos weight, needs a ration of 30-40
calories for each kilo.

The average resting man of 20 kilos weight, needs 30 cal. per kilo.
The average sleeping man of 20 kilos weight, needs 25 cal. per kilo.

Upon the basis of calorific values various diet tables have been

FOOD VALUES

273

made, by the use of which the needs of individual patients can be
met. The following, for typhoid patients (enteric fever), is
selected from a set of such diet charts prepared by Dr. Frances
C. Van Gasken and Dr. Mary P. Rupert for use in the Woman's
Hospital of Philadelphia.

TABLE A

Portion.

Food.

P.

F. C. Calories.

* pints. . .

. Milk (whole)

Si

20
24

8.5

5-4 66 975
.«: 80

i pint

. Meat broth

2. .

16 5 240

4 pint. .

. Lemon or orange jelly

12.* 72

? oz. . .

. Milk sugars

.

103

71 143-5 1696

TABLE B-

Admissible. Grams.

Approri-
P. F. C. mately
200 C.

8 oz

Gruel (with milk) (200)
Rice well cooked (50)

44 12

2 30

2 tablespoons. . .

4 OZ. . .

Junket -f- sugar (31)

44 ii
S3 10
57 9
5 7-5 9

3 oz

Custard (80)

2 tablespoons...

I OZ

Ice cream (25)

Cocoa. . (2?)

Cognac 25

Black coffee 225 c.c

From Tab
total calorific
reach the foil

F

Febrile F
period C

le B, articles may be se
value of food for each
swing averages:

roteids.. . . 300 cal.
ats 405 cal. Conva

lected
twent

les-
>eriod

at discretion. The
y-four hours should

Proteids 480 cal.
Fats 540 cal.

arbohy- cent f
drates i»3°o cal.

Carbohy-
drates 1,260 cal.

Total 2,005

Total 2,280 cal.

18

274 ANATOMY AND PHYSIOLOGY

Animal Heat. — An internal temperature of about 100° F. is
necessary to the normal activity of the body tissues. This, the
tissues themselves can accomplish with proper materials in the
form of food, and oxygen for the chemical work, the latter being
supplied in the air we breathe.

The great source of animal heat is in the most active tissues —
muscles and glands; the heat produced in these is equalized in
all tissues by the circulating fluids.

The kind of food which is eaten has a direct effect upon the
production of heat; protein substances yield more than starchy
foods, while fats yield more than proteins and starches together.

The ingestion of food causes a rise of temperature, due both to
the chemical and mechanical work of the digestive organs. This
rise is normal.

As the body is continually generating heat so it is continually
losing it in various ways — by radiation to the surrounding atmos-
phere, by conduction to the clothing, by evaporation from the
lungs and skin, etc., etc.

In cold weather heat production is desired. This can be accom-
plished by selecting heat-generating foods, by taking hot foods and
by muscle exercise; the heat thus generated can be conserved by
clothing the body in materials which prevent radiation and con-
duction, as wool or silk. In hot weather heat production is to be
avoided and heat dissipation is sought; this is facilitated by the
selection of starchy and protein foods, taking cool drinks and wear-
ing lighter garments, as cotton or linen.

For health and comfort it is necessary that a proper internal
relation be maintained between heat production and heat dissipation.
For this, the body possesses its own self-regulating mechanisms;
for ^example, muscle exercise produces heat, but the associated
activity of the sweat glands so favors heat escape, that the injuri-
ous effect of excessive body heat is prevented. Again, the viscera
concerned in digestion (notably the liver) generate much heat; by
the blood it is carried to the cooler extremities.

A high temperature of the surrounding atmosphere so affects
the nerve centers, that the respiratory function is stimulated
and evaporation from the lungs increased, at the same time
activity of the skin is very marked and evaporation of perspiration
follows.

RANGE OF TEMPERATURE 275

These natural processes of mutual accommodation result in
preserving a necessary uniform temperature of the body, which
makes it independent, within reasonable limits, of external sur-
roundings. The normal temperature, 98.4° F., is maintained so
long as the proper balance is preserved between heat production
and heat escape. Elevation of temperature is caused when produc-
tion is too rapid or dissipation is too slow. Very high temperature
indicates excessive metabolism and impaired dissipation. (Another
result of excessive metabolism is seen in the wasting of the body in
fevers, as typhoid fever.)

Subnormal temperature indicates diminished tissue change or
metabolism, suggesting impairment of vitality. (A temperature
of 77° F. is followed by death, as cell activity cannot go on in a
temperature so low.)

Range of normal temperature. — The normal adult tempera-
ture is 98 . 4° F. in the axilla, in the mouth slightly higher. It is a
degree higher in the rectum.

During early life when metabolism is active it is slightly higher
than in later years. In old age it is often a degree higher than in
middle life.

A difference of a degree is noted, in health, between the tem-
perature of early morning and evening, for example, at 5 A. M. and
5 p. M.

Average range of body temperature for different ages:

In infancy 99-99 . 5

At puberty 99

In adult life:

Axillary 98 . 4

Oral 98.8

Rectal 99 . 2

Practical Conclusions and Clinical Notes

The temperature of a patient should be taken before a meal,
or after digestion, not during it.

In cold weather hot foods containing fats are appropriate for
the generation of heat; in hot weather starchy foods and cool
drinks are in order.

Alcohol causes a temporary sense of warmth by quickening the
circulation, but this is followed by dilation of the surface capillaries

276 ANATOMY AND PHYSIOLOGY

and a consequent radiation of heat. The use of alcohol before
exposure to a low temperature should be avoided, unless some very
reliable measure is taken for preventing surface radiation.

Muscle exercise is accompanied by dilation of surface vessels
and escape of heat; this continues for some time after the exercise
has ceased, therefore, care should be taken to guard against too
great loss of heat and a consequent "cold" due to chilling of the
surface, especially when exposed to a draft of air.

The fact that the body loses heat rapidly by conduction, should
warn the nurse against putting cold garments on a delicate patient,
and especially against placing a patient in a cold bed. Remember
that the body of the patient must furnish the heat to warm the bed
and this makes an unnecessary demand upon vitality already
impaired by illness.

Small animals need more heat relatively than large ones
because their surface is greater in proportion to their bulk, conse-
quently they radiate more heat. During the first three days of
the infant's life its metabolism falls; it then begins to rise and
reaches the normal average for its size after about two weeks.

Practical point.- — Wrap the new-born child and the young infant
more warmly than it seems to need. Remember that it is not
yet able to manufacture sufficient heat to keep it comfortable.

Influence of work upon metabolism — it accelerates the proc-
esses, with increased consumption of oxygen and elimination of
carbon dioxide.

Influence of light — similar in effect (although slight in degree)
because light stimulates muscle and tissue tone.

Influence of darkness — It retards metabolism from absence of
surface stimuli.

CHAPTER XIX
THE NERVE SYSTEM

CEREBRO-SPINAL AND SYMPATHETIC DIVISIONS,
NERVE TISSUES AND THE SPINAL CORD

The preceding chapters have been devoted to the study of
many organs grouped into systems for different purposes. Of
some we can say that their functions are exercised consciously
and under voluntary control; others are so exercised to a partial
extent only ; as the muscles of the extremities and those of respira-
tion. Still others are absolutely beyond our control — as the heart,
the stomach and intestine, and others. We are, therefore, pre-
pared to find in the nerve centers of the body, a wonderful plan
for providing nerve force that shall stimulate the activities of
these widely differing organs, and at the same time bring them
into one harmonious whole.

The body functions are classified as voluntary and involuntary,
so the nerve system is arranged in two divisions — belonging
respectively to voluntary and involuntary processes, the first
being called the cerebro- spinal division; the second, the sympathetic
division.

NERVE TISSUES

The foundation cells of which nerve tissues are composed are
microscopic in size and called neurons. A neuron consists of a
nucleated cell body, an axon, and terminal divisions.

The cell body has short branches called dendrites, one of which
(sometimes two) grows longer to form the axon or axis cylinder
which becomes a nerve fiber.

Note. — The term nerve cell is often used to signify the cell body of a
neuron.

When the axon is invested with a sheath, or medulla, it is a
medullated nerve fiber, and such are found in voluntary muscles
and all sensitive parts of the body. Axons without sheaths are

277

278

ANATOMY AND PHYSIOLOGY

known as non-medullated nerve fibers, and such are found in in-
voluntary muscles and in the walls of internal organs.

Structures composing a medullated nerve fiber:

1. The axon or axis-cylinder.

2. Medulla or myelin (white substance of Schwann).

3. Neurilemma, a transparent membrane inclosing the myelin (sometimes
absent).

Dendrites

Nerve cell

Medullated
- fiber

Nerve cell

FIG. 172. FIG. 173.

FIGS. 167, 168. — NERVE CELLS. — (Brubaker.)

Structures composing a non-medullated nerve fiber:

1. The axon or axis-cylinder.

2. Neurilemma (sometimes absent).

Medullated nerves are found in voluntary muscles, skin, mucous ana serous
membranes, joints and special sense organs. They constitute the main
portion of the Cerebro-spinal Division.

Non-medullated nerves are found in glands, vessels, hollow viscera, and
muscle fibers at roots of hairs. They constitute the main portion of the
Sympathetic Division.

The axons or nerve fibers terminate in fine branches, which
connect them either with various organs or with the dendrites of
other cell bodies, as the case may be.

For want of more accurate language, we say that impulses are

NERVES AND NERVE CENTERS 279

transmitted through fibers either to or from cell bodies. If to the body,
the fiber and cell constitute an afferent neuron (afferent, bearing
toward) ; if from the cell body the neuron is efferent (efferent, bearing
away) . Afferent nerves are centripetal; efferent nerves are centrifugal.

Important to remember.— The cell body is necessary to the life
of the fiber; if separated from the cell body the fiber will die.

The distinguishing characteristics of nerve tissue are sensitive-
ness or irritability and conductivity.

THE CEREBRO-SPINAL DIVISION OF THE NERVE

SYSTEM

The brain and spinal cord with their nerves constitute the
cerebro-spinal system, and since the brain and cord contain the
largest and most important centers, this is often called the central
nerve system (Fig. 174).

Nerve tissues in the cerebro-spinal system appear to the eye
as of two kinds, gray and white. The gray tissue, commonly called
"gray matter," is composed of cell bodies and their branches. The
so-called "white matter" is composed of medullated fibers belonging
to the cells.

A nerve (of the cerebro-spinal system) consists of many fibers
bound together; it resembles in appearance a white cord and may
be so small as to be distinguished with difficulty, or as large as a
child's finger — like the great sciatic nerve.

A nerve is constructed after the same plan as that of a muscle. A connect-
ive tissue sheath (epi-neurium) sends partitions (peri-neurium) between
bundles of fibers, and a delicate membrane (endo-neurium) surrounds each
fiber.

Nerves divide into branches which may interlace with others or join them
in a common sheath, but no fiber ever unites with another. Each one con-
tinues throughout the length of the nerve of which it forms a part.

Nerve centers are the gray cell bodies to which nerves belong,
and which are necessary to the life of the fibers.

This term is commonly used to signify a collection of cells
whose fibers form nerves having a special function, or which pre-
side over a group of movements. (A definite collection of gray
cells is also called a ganglion.} Motor nerves transmit motor
impulses from centers to muscles, while sensory nerves transmit
1 For description of the Sympathetic Division see page 316.

280

ANATOMY AND PHYSIOLOGY

impressions from the various parts of the body to the centers which
receive them. We commonly speak of motor nerves as running
down, and sensory nerves as running up, referring them to the
spinal cord or brain.

THE SPINAL CORD

The spinal cord lies within the spinal canal in the spinal
column, being continuous with the brain. It is a round white
structure about seventeen inches long, ex-
tending from the atlas to the second lum-
bar vertebra, where it ends in a slender ter-
minal filament which continues to the end
of the canal. The thickness is about half
an inch, being greater in the lower cervical
and lower dorsal regions, making the cervical
and lumbar enlargements where nerves are
given off for the extremities. It presents
a median fissure in front and another at the
back, marking off its right and left halves.
Other fissures divide each half into anterior,
lateral, and posterior columns or tracts.

A transverse section will show that the
interior of the cord is grayish in color in-
stead of white, and this portion is largely
made up of the gray cell bodies and their
branches, arranged in masses which are con-
tinuous throughout the length of the cord.

The section will also show that the area
occupied by the gray portion roughly re-
sembles two crescents (one in either side),
connected together across the middle. The
extremities of the crescents are called the
FIG. i74^-THE BRAIN anterior and posterior horns.

A canal, called the central canal, runs
through the center of the gray portion. It
may be traced throughout the length of the cord but is easily seen
only in the upper part. It contains cerebrospinal fluid.

The white portion consists of the bundles or tracts of the cord
(often called columns, the name tract being applied to divisions of

AND SPINAL CORD. —
(Quain, after Bourgery.)

THE DURA MATER

28l

the columns). There is a general division into three in each half—
the anterior, lateral, and posterior tracts. The fibers in the anterior
and a portion of the lateral tracts are connected with the cells of
the anterior horn. They conduct motor impulses. The fibers in
the posterior and a portion of the lateral
tracts are connected with the posterior
horn, and conduct sensory impressions.

All three columns contain associating A
fibers which connect different parts of the
cord with each other. These are im-
portant.

MEMBRANES OF THE SPINAL CORD

The pia mater. — A delicate membrane
which bears the blood-vessels and is very
closely applied to the surface of the cord
(the vascular membrane of the cord).

The arachnoid (web-like). — Outside of
the pia mater, this has been classed among
serous membranes because its epithelium
secretes a fluid like serum; it is a single
fibro-serous sheet of membrane (not a
closed sac) which surrounds the cord
loosely. The fluid within it (cerebro-spi-
nal fluid) protects the cord from friction
and vibrations.

The dura mater. — A strong white
fibrous membrane, tubular in shape, in anterior
which the cord is loosely suspended. It is attached above to the
margin of the foramen magnum.

The space between the dura and the arachnoid is the subdural
space; that between the arachnoid and pia is the subarachnoid
space; they contain cerebro-spinal fluid. The subarachnoid space
is largest in the lower portion. (The fluid in this space mixes with
that of the central canal through a small opening in the pia, at the
base of the brain.)

The membranes are also called the meninges, and their blood-
vessels are the meningeal vessels. Spinal meningitis is inflamma-
tion of the meninges of the cord.

FIG. 175. — THREE SECTIONS
OP SPINAL CORD.

A, Cervical region; B,
thoracic region; C, lumbar
region; p, posterior horn; a,

282

ANATOMY AND PHYSIOLOGY

Surgical note. — The operation of lumbar puncture is for the purpose of
opening the dura and arachnoid and drawing .off a certain quantity of
cerebrospinal fluid.

SPINAL NERVES

A spinal nerve is a collection of
motor and sensory fibers connected
with the spinal cord by two roots — an
anterior root running from the motor
cells and tracts and a posterior root
running to the sensory tracts and cells.

The two roots become imbedded
in one sheath at the intervertebral
foramen which transmits the nerve
from the spinal canal.

Note. — The "ganglion of the root" is a
small ganglion on the posterior root where the
true root fibers arise.

The ganglion contains the cell-bodies of
fibers in the posterior roots; they are neces-
sary to the life of these roots. Two axons
belong to each ganglion cell; one becomes
part of a spinal nerve and ends in a sensitive
part of the body (skin, mucous membrane,
muscle tissue and lining of joints) ; the other
forms a fiber of the posterior root of the same
spinal nerve, and enters the cord to become
associated with cells of both posterior and
(The fibers of the anterior roots arise in the cells of the anterior

FIG. 177. — MEMBRANES OF SPI-
NAL COED.

i, Dura mater; 2, arachnoid;
3, post, root of nerve; 4, ant.
root of nerve, divided; 5, pia
mater; 6, linea splendens. —
(Morris, after Ellis.)

anterior horns,
horns.)

Clinical note. — Since the spinal nerves contain both motor and sensory
fibers, they are called mixed nerves; and since the antero-lateral divisions of
the cord are motor tracts, and the postero-lateral divisions are sensory
tracts, we can understand how injury in one region will cause paralysis of
motion, and injury in the other will cause paralysis of sensation; while injury
of a mixed nerve will cause loss of both motion and sensation in the parts to
which the nerve belongs. *

The next chapter will present the spinal nerves. Certain
points of interest in connection with their structure and arrange-
ment are here indicated by way of preparation for the study.

It will be noted that the spinal nerves are mixed nerves. That
is, they are connected with both ventral and dorsal columns of
the cord and contain both motor and sensory fibers until they have

TERMINAL BRANCHES OF NERVES

283

made several divisions, when certain of the sensory fibers are no
longer found in the same sheath with the others, but are grouped
into nerves which belong to sensitive surfaces.

The terminal branches of all nerve fibers differ with their func-
tion. The fibrils of motor spinal nerves end as tiny expanded
plates (end plates) which are applied to muscle fibers. (See Fig.
178.) Those of sensory spinal nerves are modified for the purpose
of receiving impressions from skin, mucous membranes, joints,
periosteum and, to a lesser extent, from muscle and bone tissues.

Sensory
nerve-fiber.

Muscle
fibers.

Motor plate.

Nerve-fiber
bundle.

FIG. 178. — MOTOR NERVE-ENDINGS OF INTERCOSTAL MUSCLE-FIBERS OF A
RABBIT. Xiso.— (Stohr.)

The terms origin and distribution are employed in the description of indi-
vidual nerves. When applied to motor nerves they are used appropriately
and are easily understood, but in connection with sensory nerves it must be
remembered that their origin or nerve beginning is by the "terminal branches. "
The impulse transmitted by sensory nerves is aroused by the stimulus
of impressions on these "branches" and received by the central cell; while
that of a motor nerve originates in the central cell, to be transmitted to a muscle
where it is really distributed.

In describing mixed nerves it is necessary to conform to custom and speak
of the whole nerve as arising by its central connections and as being distributed
at the periphery (by which is meant the place where its function is manifested).

By the above it is evident that the conductivity of the tissue is
specialized in the axon fibers; the sensibility in the terminals and
cell bodies. The chemical changes in these parts are supposed to
be the origin of nerve impulse or nerve force.

Cervical

12 Thoracic

5 Lumbar

5 Sacral

FIG. 179. — DIAGRAM OP
SPINAL NERVES.

CHAPTER XX
THE SPINAL NERVES

There are thirty-one pairs of spinal
nerves. They leave the spinal canal at
the intervertebral foramina in the differ-
ent regions and are named accordingly.

Cervical 8

Thoracic 12

Lumbar 5

Sacral 5

Coccygeal.

The first cervical, emerging above the atlas,
is called the suboccipital.

The cauda equina. — The spinal cord, being
17 inches long, reaches only to the second
lumbar vertebra, therefore the nerves emerg-
ing through the foramina below this level must
have lain in the canal for some distance before
leaving it, especially those which appear in
the lowest or pelvic region. If the canal be
opened at the back and the cord lifted out,
these long nerves are seen hanging from it in
a crowd, suggesting the appearance of a
horse's tail, the "cauda equina," which there-
fore is composed of the lumbar, sacral, and coc-
cygeal nerves while they are still in the neural
canal. The terminal filament extends down-
ward in their midst.

All spinal nerves divide at once into
posterior and anterior divisions, both di-
visions containing motor and sensory
fibers (Fig. 181).

The posterior divisions send nerves
to posterior regions of neck and trunk ;
the anterior divisions (communicate with
the sympathetic system, and then) send
nerves to anterior and lateral regions of
284

NERVE PLEXUSES

285

the neck and trunk, and to the upper and lower extremities.1
In all regions except the thoracic, the anterior divisions interlace
with each other to form plexuses before giving off nerves.
A nerve plexus is a network formed by
branches of several main nerves which have
different central connections. (See p. 296.)
From the plexus other nerves proceed to
their separate distributions.

A nerve made up of fibers which have
been part of a plexus conveys impulses to
or from several different parts of the spinal
cord.

The most important plexuses are:

The cervical plexus (formed by the upper four
cervical nerves).

The brachial plexus (formed by the lower four
cervical and first thoracic nerves).

The lumbar plexus (formed by the upper three
and part of the fourth lumbar nerves).

The sacral plexus (formed by the lower lum-
bar, and upper three and most of fourth sacral
nerves).

The larger nerves only are described in the
text. Resumes are added for reference.

For nerves supplying the joints see page 74.

FIG. 1 80. — CAUDA EQUINA. —
(Morris.)

FIG. 181. — SHOWING DIVISION OF
NERVE.

i, Dura mater; 2, arachnoid; 3,
ganglion of post, root; 4, ant. root; 5,
space containing spinal fluid; 6, post,
division of nerve. — (Holden.)

1 The communicating branches to sympathetic ganglia are of great importance,
serving to connect the cerebro-spinal and sympathetic division into one great nerve
system. (They are the white rami communicanles.)

286

ANATOMY AND PHYSIOLOGY

CERVICAL NERVES

Posterior divisions. — These send branches to the back of the
head as well as muscles and skin of the neck. Largest posterior
branch. — The great occipital (from second cervical), to supply the
scalp.

Anterior divisions. — The upper four form the cervical plexus.
The lower four enter the brachial plexus.

FIG. 182. — THE PHRENIC NERVES, RIGHT AND LEFT, RUN DOWNWARD ON EITHER
SIDE OF THE GREAT VESSELS AND THE HEART. — (After Morris.)

The cervical plexus. — Most of the branches of this plexus
supply muscles of the neck (front and side). One exception is
the great auricular (auricularis magnus) which supplies the external
ear. Another is the —

Most important nerve of this plexus, the phrenic. — It passes
downward through the thorax (between the lung and heart) to
supply the diaphragm (Fig. 182). Its importance is due to the
fact that the diaphragm is one of the principal breathing muscles,

THE BRACHIAL PLEXUS 287

and the nerve has for that reason been called the "internal respira-
tory nerve of Bell." (Sir Charles Bell was a famous anatomist in
former times.)

The brachial plexus. — This plexus is so named because most
of its branches supply muscles of the upper extremity (including
the shoulder) and those connected with it.

First important branch, given off in the neck — the long thoracic.
It passes downward along the side of the thorax to supply the an-
terior serratus muscle (p. 102). This muscle is used in forced res-
piration and the nerve has been called therefore the "external
respiratory nerve."

The greater part of the branchial plexus is situated in the
axilla; most of its branches are given off there

f supraspinatus
Branches: Suprascapular, to < *

( infraspinatus

Three large cords: Lateral, medial, posterior.
Branches of the cords:

From lateral cord: Thoracic, to pectoral muscles.

Musculo-cutaneous, to biceps and brachialis (and

their integument).
Upper root of median nerve.
From medial cord: Lower root of median nerve.

Thoracic, to pectoral muscles.
Cutaneous, to integument of forearm.
Ulnar, to ulnar muscles.

( subscapularis, teres major,
From posterior cord: Subscapular to I latissimus dorsi (the long sub-

{ scapular).

Axillary, to deltoid and teres minor.
Radial, to posterior of forearm and hand.

The three large nerves derived from the brachial plexus are:

The ulnar from the medial cord.

The median from the medial and lateral cords.

The radial from the posterior cord.

The ulnar nerve runs downward in the medial side of the arm,
passes behind the medial epicondyle into the forearm, and ends
in the palm (Fig. 183).

In the forearm it supplies: Flexor carpi ulnaris.

Flexor digitorum (profundus) partially.
In the hand it supplies: Interossei.

Little finger muscles.

Thumb muscles (one and a half).

288

ANATOMY AND PHYSIOLOGY

Axillary artery

Suprascapular nerve and artery

FIG. 183. — BRACHIAL PLEXUS AND AN-
TERIOR NERVES.

FIG. 184. — THE RADIAL NERVE.

MEDIAN AND RADIAL NERVES 289

The median nerve runs downward in the arm, close under the
border of the biceps muscle. It then passes in front of the elbow
joint into the forearm, and continues between the layers of flexor
muscles to the palm.

In the forearm it supplies: Flexor carpi radialis.

Flexor digitorum (sublimis).

Flexor digitorum profundus (partially).

Pronators.
In the hand it supplies: Thumb muscles (except one and a half).

The radial nerve passes to the back of the arm, winding across
the humerus in the radial groove, under the triceps muscle (Fig.
184).

Just above the elbow it divides into two branches, the deep and
superficial branches of the radial nerve.

The superficial branch is a cutaneous nerve. It runs downward
in the radial side of the forearm to supply integument of the hand
and fingers, posteriorly.

The deep branch passes to the back of the forearm, lying under
cover of extensor muscles, all of which it supplies.

Branches of the radial nerve:

In the arm: To the triceps.

To brachio-radialis.

To brachialis (partially).
Branches of the deep branch of the radial nerve:

In the forearm: To the extensor carpi radialis (long and

short).

To the extensor digitorum (communis).

To the extensor of index finger.

To the extensor of little finger.

To the extensors of the thumb.

To the Supinators.

Resume.' — The general distribution of the muscle nerves arising
from the brachial plexus, is to deep muscles of the neck and the
external respiratory muscle (anterior serratus); to shoulder and
axillary muscles; arm, forearm and hand.

The three long muscular nerves derived from the brachial plexus
are the ulnar nerve from the medial cord, running down behind
the medial epicondyle into the forearm and hand (supplying ulnar
muscles, little finger muscles and the interossei, and a part of the
thumb group) ; the median nerve from the medial and lateral cords,
19

290

ANATOMY AND PHYSIOLOGY

running down along the medial border of the biceps muscle into the
forearm, to end in the palm (supplying the biceps and brachial
muscle, all of the flexors of the forearm except on the ulnar side,
and most of the thumb muscles) ; the radial nerve from the pos-
terior cord, running in its groove to the front of the lateral epicon-
dyle, and dividing into the deep and superficial branches of the radial
nerve. By the radial and its deep branch all of the posterior mus-
cles of the arm and forearm are supplied.

Nerves of the skin of the hand. — Front of the thumb, index,
middle, and one-half of the ring finger, the median nerve. Back of
thumb, index, middle, and one-half of ring finger, the superficial

FIG. 185. — DORSAL SURFACE OF LEFT
HAND.— (Morris.)

FIG. 1 86. — AN INTERCOSTAL NERVE
— (Holden.)

branch of the radial nerve. Both front and back of little finger and
one-half of ring finger, the ulnar nerve.

Points of interest. — The ulnar nerve, in the arm, is with the inferior pro-
funda artery and passes behind the medial epicondyle (it may be easily felt in
the groove behind the epicondyle, where pressure causes a sensation of pain
and tingling as far as the little finger). In the forearm it is on the ulnar side
of the ulnar artery and they pass in front of the wrist.

The median nerve, in the arm, is with the biceps muscle and brachial
artery, and they pass in front of the elbow; in the forearm, it lies between the
deep and superficial muscles and passes with their tendons in Jronl of the
wrist.

The radial nerve, in the arm, lies in the groove for the radial nerve be-
tween two heads the triceps muscle, with the superior profunda artery, and
comes to the front of the elbow.

Its superficial branch, in the forearm, is on the radial side of the radial
artery; it winds around behind the wrist-joint.

THORACIC NERVES

291

The deep branch of the radial nerve is in the back of the forearm with the
dorsal interosseous artery; they do not extend below the wrist.

(For the distribution of nerves to the principal joints, see page 74.)

THORACIC NERVES (FIG. 186)

There are twelve pairs of thoracic
nerves:

Posterior divisions.' — These send
branches to muscles and skin of the
back.

Anterior divisions. — These form
the intercostal nerves; the first assists
in the formation of the brachial
plexus. All run in the grooves under
the borders of the ribs, supplying in-
tercostal muscles, also the skin over
the muscles. The lower ones also
supply upper abdominal muscles and
skin. They accompany intercostal
arteries.

LUMBAR NERVES

There are five pairs of Lumbar
Nerves.

Posterior • divisions. — These send
branches to muscles of the back; and
skin of the back, hip, and sacral region.

FIG. 187. — THE FEMORAL
NERVE.

i, Femoral nerve; 2, 3, small
nerves from lumbar plexus; 4, 5,

Anterior divisions. — I he upper three 6,7,8,9,10, u, n, branches of
and a portion of the fourth form the femoral °erve: I2« I2> '3« '4,

long saphenous nerve and its

lumbar plexus. The remainder of the branches; 15, obturator nerve; 16,
e j A.-L. i- i c j.1- .crii. r r7» J8, 19, branches of obturator

fourth and th? whole of the fifth form ne;ve;f a£ 2I> lumbo-sacral cord;

the lumbo-sacral cord (Fig. 187). 23, external cutaneous nerve.-

The lumbar plexus. — This plexus

lies within the°bdomen, in the substance of the psoas muscle. Its
branches supply abdominal walls, and front and sides of the thigh
(also in temagumef both regions). They are all given off in the

t.anoenbd

Branches: the principal are:

ANATOMY AND PHYSIOLOGY

Ilio-hypogastric, cutaneous to hypogastrium, and over the ilium (dorsum).
Inguinal, to internal oblique and transversus muscles.
Genilo-femoral, to round ligament of uterus, cremaster muscles of spermatic
cord.

Obturator, to the external obturator and the four adductors.
Femoral, to the quadriceps muscle (rectus and three vasti).

The femoral nerve (anterior crural) is the largest branch of the
lumbar plexus. It passes under the inguinal ligament, from the
abdomen, into the thigh (on the lateral side of the femoral artery),
and breaks up at once into branches — cutaneous and muscular, for
the four large divisions of the quadriceps extensor muscle and the
integument which covers them.

The long saphenous branch of the femoral nerve is the longest
nerve in the body, running nearly the whole length of the extrem-
ity; it supplies integument only, on the medial side of the leg and
foot

The lumbo-sacral cord passes into the pelvis to unite with
sacral nerves and to form the sacral plexus.

SACRAL NERVES

Posterior divisions. — These send branches to muscles and skin
of the back of the pelvis.

Anterior divisions. — The upper three, and greater part of the
fourth, join the sacral plexus.

The sacral plexus. — The branches of this plexus supply the
muscles within and around the pelvis, the posterior part of the
thigh, and the entire leg and sole of the foot.

Branches: (All leave the pelvis through the great sciatic foramen.)

Gluteal, two (superior and inferior) to glutei muscles.

Pudic, to the levator ani, rectum (sphincter ani), perineum, and external
genital organs. (Reenters the pelvis through small sciatic foramen.)

Small sciatic, to posterior thigh and external genital organs. This is a
cutaneous nerve.

Great sciatic, to posterior thigh, and entire leg and foot (except medial
border) muscles and skin.

The great sciatic nerve is the largest nerve in the body. It
leaves the pelvis by way of the great sciatic notch and runs down-
ward between posterior thigh muscles to the popliteal space,
where it divides into tibial and common peroneal nerves (Fig. 188).

SCIATIC NERVE

2Q3

The only portion of the great sciatic nerve which is not covered by muscles,
lies in the deep groove between the great trochanter of the femur and the
tuberosity of the ischium.

\feusi

Branches:

In the thigh. — To the Biceps,
Semitendinosus.
Semimembranosus.
Calf muscles.

The division of the great sciatic
nerve occurs in the upper part of
the popliteal space. The tibial
nerve (internal popliteal) runs
down through the popliteal space
(with the popliteal artery and
vein) to the leg. It then descends
under cover of the calf muscles to
the ankle; below the medial mal-
leolus it divides into medial and
lateral plantar nerves.

Branches:

In the leg. — To the Tibialis posticus.
Flexor digitorum (longus).
Flexor hallucis.

In the foot. — By medial plantar, to
great toe muscles and inter ossei.

By lateral plantar, to muscles of
little toe.

The tendons of the tibialis and two
long flexors of toes pass behind the
medial malleolus. They extend the foot.

The common peroneal nerve
(external popliteal) winds around
the neck of the fibula to the front
of the leg, and divides into the
deep peroneal and superficial pero-
neal nerves.

The deep peroneal (formerly
anterior tibial) descends to the
ankle, and ends on the dorsum of
the foot between the first and second toes.

Gluteal n.

Sciatic n.

• Popliteal artery
•Tibial n.

1 Peroneal n.

Ant. lib. artery

Tibi&l n.

Post. tib. artery

FIG. 188.— THE SCIATIC NERVE.

294

ANATOMY AND PHYSIOLOGY

Branches:

In the leg. — To the Tibialis anticus.
Extensor hallucis.
Extensor digitorum (longus).
Peroneus tertius.

In the foot. — Extensor digitorum (brevis).

The tendons of these muscles pass in front of the ankle-joint. They flex
the foot.

The superficial peroneal (musculo-cutaneous) runs downward
in the substance of the peroneal muscles to the foot.

Branches:

Muscular. — To the Peroneus longus, peroneus brevis.

Cutaneous. — To dorsum of foot.

Their tendons pass behind the lateral malleolus. They extend the foot.

Tibialis posterior
Cruciate ligament

Tibialis
posterior

Tibialis

anterior

Tendo Arcfaillis

Flexor digitorum

longus
Posterior tibial

artery
Tibia nerve

Flexor digitorum longus

FIG. 189. — RELATIONS OF PARTS BEHIND THE MEDIAL MALLEOLUS. — (Heath.)

Points of interest. — The superior gluteal nerve, with the superior gluteal
artery; the sciatic nerve, with the sciatic artery; and the pudic nerve, with the
pudic artery, all pass out from the pelvis through the great sciatic foramen; the
pudic nerve and artery return through the small sciatic foramen.

The obturator nerve and the obturator artery pass through the obturator
foramen.

The femoral nerve passes under the inguinal ligament on the lateral side
of the femoral artery.

THE COCCYGEAL PLEXUS

The remaining sacral nerves and the coccygeal nerve communi-
cate in a small plexus, which is important in that it sends branches
to the viscera of the pelvis.

NERVE REFLEXES

295

Summary

The spinal nerves are distributed to all skeletal muscles and
integument except those of the front of the head, face, and chin.
Through sympathetic connections they also supply secreting cells
of glands and walls of viscera.

FUNCTIONS OR PHYSIOLOGY OF THE SPINAL CORD
AND SPINAL NERVES

The spinal cord is so intimately connected with the brain by
conducting fibers in the tracts, that it is impossible to explain all
of its functions without referring to the brain, but certain ones

:sp.c.

FIG. 190. — DIAGRAM SHOWING THE STRUCTURES INVOLVED IN THE PRODUCTION OF

REFLEX ACTIONS. — (G. Bachman.)

r.s., Receptive surface; af.n., afferent nerve; e.c., emissive or motor cells in the
anterior horn of the gray matter of the spinal cord, sp.c; ef.n., efferent nerves^ dis-
tributed to responsive organs, e.g., directly to skeletal muscles, sk.m., and indi-
rectly through the intermediation of sympathetic ganglia, sym. g., to blood-vessels,
b.v., and to glands, g. The nerves distributed to viscera are not represented.

may be exercised independently, and a few of these will be con-
sidered briefly in this connection.

The spinal cord a center for reflex action. This is one of the
most important of its functions and the simplest form of nerve
and muscle action. Acts which may be performed without
thinking of them are reflex, also those which are performed
independently of the will although with perfect consciousness.

296 ANATOMY AND PHYSIOLOGY

For example, we shiver with cold, or tremble from excitement;
these are purely reflex acts of which we may be conscious although
we are unable to control them; the action of the heart is some-
times very evident to the senses, as in palpitation, etc., but beyond
our power to regulate.

In each lateral half of the cord the cell tissue is grouped in
crescents. Fibers in the posterior tracts transmit sensory impulses
from various parts of the body to cells in the posterior horns of the
crescents. Fibers in the anterior tracts transmit motor impulses
from cells in the anterior horns to various parts of the body (their
axons arise in cells of the anterior horns) (Fig. 190).

Here we have the simple reflex arc, or the apparatus for
reflex muscle action. A sensory or afferent nerve receives an
impression, and transmits a series of impulses to the spinal cord.
These are received by a cell which in its turn is stimulated, and
liberates energy to be conducted by a motor or efferent nerve to a
muscle, and the muscle contracts; or to a gland — the gland
secretes; or to a vessel wall — the caliber is changed. These acts
are comparatively simple.

Most muscle activities, however, are complex, requiring the
combined action of several organs; in these cases many motor cells
and nerves must be stimulated, and this is accomplished by means
of additional neurons within the cord, whose fibers associate the
activities of different regions. For instance, an unsuspected blow
upon the hand is followed instantly by a drawing back of the hand
and arm — most of the muscles of the upper extremity will have
been called into action; in other words, many motor cells (in the
lower cervical region of the cord) have been stimulated to a sudden
liberation of energy, showing the effect of one stimulus when
conducted by connecting fibers to many cells in the cord.

Walking was in the beginning a purely voluntary act, but the
centers which control it become, by education, independent, and
it takes its place among the reflexes. So with piano-playing, and
many other acts.

The complicated motor response is provided for by the arrangement known
as a nerve plexus, which is formed by interlacing branches of nerve trunks.
An illustration is seen in the brachial plexus, where five large trunks are
reduced to three while passing under the shoulder joint; then, by branching
and interlacing, the fibers are so arranged that each nerve contains fibers

TENDON REFLEXES 297

from two or three of the main trunks proceeding from the plexus and is dis-
tributed to a group of muscles acting in harmony.

Tendon reflex. — A familiar example of tendon reflex is the
"knee jerk" or patellar reflex. This may be elicited by striking
the patellar tendon when partly stretched. The impression thus
produced quickly reaches the motor cells which innervate the
quadriceps muscle, and the leg is slightly and suddenly extended.
(There are several tendon reflexes.)

Skin reflex. — Irritation of the sole of the foot causes the
plantar muscles to contract, a plantar reflex. Scratching the skin
of the side of the abdomen causes contraction of abdominal
muscles, abdominal reflex. (There are other skin reflexes.)

The spinal cord contains centers for controlling the tone of
vessel walls or vascular tone. Also for stimulating the action of
secreting glands, and for muscle action of viscera. These functions
are exercised through the sympathetic ganglia with which it is
widely connected; they will be referred to in Chapter XXII.

Finally, it contains centers which influence (or control) certain
processes of nutrition — trophic centers.

It appears at once that the spinal cord is able, from the wide
distribution of its nerves, to provide for most of the activities of
the body.

Taken as a whole it may be regarded as a great common center
of sensation and motion; and because of many connecting fibers
running upward, downward, and transversely, it can combine
and to some extent regulate the functions of many different parts,
so that systematic groups of movement, or series of movements, may
be executed by organs more or less distant in the body.

In other words, the spinal cord can to some extent coordinate
the functions of the spinal nerves and skeletal muscles.

To repeat the functions of the spinal cord, they are to preside
over:

1. Reflex action.

2. Muscle tone.

3. Vessel tone.

4. The action of secreting glands.

5. Nutrition (trophic action).

6. Coordination of skeletal muscles.

298 ANATOMY AND PHYSIOLOGY

These may all be exercised independently of the brain, by cells
in the posterior and anterior horns with their sensor and motor
nerve connections. v (Other functions will be mentioned in connec-
tion with those of the brain.)

The function of the spinal nerves is to connect all parts of the
body (except face, chin and anterior part of head) with the spinal
cord, for the purpose of conducting sensor and motor impulses to
and from the cord.

NERVE STIMULUS

In referring to motor nerves we have thus far mentioned their
natural stimulus only, that is — the impulse generated by a sensor
or motor cell. The electric current applied to a motor nerve in any
part of its course will excite its activity, showing in muscle contrac-
tion, etc. This is an artificial stimulus, and the most powerful
one known.

CHAPTER XXI
THE BRAIN AND CRANIAL NERVES

The cerebro-spinal or central nerve system comprises the
Brain and Spinal Cord with their nerves. The spinal cord and
its nerves are already described in Chapters XIX and XX.

The brain1 is ovoid in shape, composed of gray cells and white
fibers, situated within the cranial cavity and continuous through
the foramen magnum with the spinal cord.

FIG. 191. — THE EXTERNAL SURFACE OF THE BRAIN. — (Deaver.)

The surface consists of gray cells and their branches and is
called the cortex of the brain, while the interior is white, with several
ganglia imbedded within it.

The surface or cortex of a well-developed brain is marked by
many fissures, separating curved ridges called convolutions (or
gyres}, the number and depth of which correspond with the degree
of development, the brain of a new-born child being comparatively
smooth.

1 A review of pages 277 and 278 is recommended before studying the description
of the brain.

2QQ

300

ANATOMY AND PHYSIOLOGY

The white portion is composed of white fibers. They run in
many directions. Some connect the different main divisions of
the brain; others run from one part of the cortex to another;
others still, in great number, connect the brain and spinal cord
(Fig. 192). Taken together, they make up the mass of the brain
itself.

The brain has four principal parts, the cerebrum, cerebellum,
medulla oblongata, and pons Varolii.

FIG. 192.

The letters mark white fibers. They connect the cortex with other parts, also
different parts of cortex together. Many fibers are seen to pass through the basal
ganglia. The Roman numerals indicate nerves. — (Brubaker, after Starr.)

The cerebrum is the largest division and occupies nearly the
whole cranial vault. It is divided into two hemispheres, right and
left, by a longitudinal fissure. At the bottom of this fissure white
fibers are seen to pass from one side to the other, thus forming a
transverse commissure, connecting the hemispheres, and called the
corpus callosum (Fig. 193). Each hemisphere is marked off by
specially deep fissures, into lobes, the principal ones being the
frontal, parietal, occipital, and temporal. The principal fissures
between the lobes are: the fissure of Rolando between the frontal
and parietal; the parieto-occipital, between the parietal and occi-

THE BASAL GANGLIA.

301

pital; and the fissure of Sylvius, between the temporal lobe below
and the frontal and parietal above it.

Important note. — The fissure of Rolando is often called the central fissure,
and the convolutions in front of and behind it, are called the central convolutions
(anterior and posterior central).

Within the white substance of the hemispheres are the largest
ganglia in the brain, and since they are situated near the base,
they are called basal ganglia. They are the optic lhalamus, the
lentiform nucleus, and the caudate nucleus (Fig. 195). The white

FIG. 193. — MEDIAN SURFACE OF A HEMISPHERE, SHOWING THIRD AND FOURTH
VENTRICLES; ALSO THE CORPUS CALLOSUM DIVIDED, AND THE STRUCTURE OF THE
CEREBELLUM WITH THE PONS IN FRONT OF IT. THE PITUITARY BODY is SUSPENDED

FROM THE FLOOR OF THE THIRD VENTRICLE. — (

matter between the optic thalamus and the other two, constitutes
the internal capsule. Here are the fibers which connect centers in
the cortex with those in the spinal cord; hence the great importance
of the internal capsule.

The white fibers of the cerebrum are classified in three groups: i. those
which connect different parts in the same hemisphere, or association fibers;
(Fig. 201) 2. those which connect parts in one hemisphere with similar
parts in the other, or commissural fibers; 3, those which connect the
cortex with the ganglia of the brain and spinal cord, or projection fibers
(Fig. 192 shows projection fibers of the right half of the brain).

The hemispheres are not solid, but each encloses a cavity
called the lateral ventricle, shaped like the italic letter / with a

302

ANATOMY AND PHYSIOLOGY

projecting arm (laterally and downward). The extremities of the
ventricle are called horns; the anterior horn being in the frontal
lobe, the posterior horn in the occipital, and the lateral or descend-
ing horn in the temporal lobe. The great ganglia of the brain are
in the floor of the lateral ventricles (hence called basal ganglia).

The lateral ventricles are named
like the hemispheres — right and left.

(There are certain other basal ganglia
which are important, although smaller in

size.)

The cerebellum, or little brain,
also consists of white matter covered
with gray. It has two hemispheres
which are not definitely separated
like the hemispheres of the cerebrum,
but are connected by a median por-
tion called the vermis, or worm. The
convolutions are but slightly curved
and are called ridges, and the furrows
(or sulci) are very deep; a section
shows that they are so arranged as
to resemble the branches of the tree
called arbor vita (Fig. 193).

The cerebellum is situated in the
cerebellar fossae of the occipital bone.

The medulla oblongata, although

FIG. 194. — PONS AND MEDULLA,
ANTERIOR SURFACE.

i, 2, 3, Structures belonging to
cerebrum; 4, crura of cerebrum; 5,
pons Varolii; 9, 10, n, 13, 14,
lateral surface and membranes of
medulla; 7, pyramid; 8, decussa-

nerves; 28, 29, ist and 2 d spinal of the foramen magnum), is the up-

nerves. — (Sappey.) . , ,. - ,, ,

per enlarged portion of the spinal
cord and, like it, is white externally and gray within.

Its anterior columns are called the pyramids or pyramidal
tracts, and consist of motor fibers passing downward from the
brain. Most of the fibers of each pyramid cross to the opposite
side, appearing to interlace in the median fissure, the decussation
of the pyramids, to form the crossed pyramidal tract; the others
pass downward as the direct pyramidal tract and cross, a few
at a time, at lower levels in the cord. Thus it is that motor
fibers coming from one side of the brain pass to the other side

VENTRICLES OF BRAIN 303

of the cord, and this is the explanation of paralysis of one side
of the body, following injuries of the other side of the brain.

The posterior columns of the medulla contain sensory fibers
going upward to the brain, while the lateral tracts contain both
motor and sensory fibers (like the cord). Most of the sensory
fibers also cross at different levels.

The medulla contains centers for the most important nerves of
the body — respiratory, cardiac, vaso-motor, etc.

The pons Varolii, or bridge of Varolius, is situated in front of
the medulla, below the cerebrum and cerebellum, and so named
because fibers run through it from all three of the other parts of
the brain, as though it were a bridge between them. It, also, is
white externally and gray within, and is not unlike the cord,
although in a still more modified form than the medulla.

Two large nerve bundles are seen diverging from the anterior border of the
pons, the crura of the cerebrum (often called peduncles). They contain all of
the motor and sensory fibers of the cerebrum which pass between the pons
and the cord. The fibers to and from the cerebellum form peduncles oj
the cerebellum (smaller in size).

THE FIVE VENTRICLES OF THE BRAIN (Fig. 195)

The five ventricles are different portions of one cavity, which is
continuous with the central canal of the spinal cord. The two
lateral ventricles have been mentioned. The third ventricle is
between them, and the fourth ventricle is behind the third, being
in the medulla and pons; some of the most important nuclei or
centers of the body are imbedded in the floor of the fourth ventricle.

Each lateral ventricle communicates with the third through an
opening called the foramen of Munro; the third communicates with
the fourth through the aqueduct of the cerebrum (aqueduct of
Sylvius), a slender canal in the crura and pons; and the fourth
ends in the central canal of the cord. These spaces are therefore
continuous, and they contain cerebro-spinal fluid.

The so-called fifth ventricle is not a portion of the general cavity — not a
true ventricle. It is a narrow space in front of the third, having no opening
whatever.

Clinical notes. — Hydrocephalus is caused by an accumulation of fluid in
the ventricles, enlarging them and pressing upon the brain substance, and

3°4

ANATOMY AND PHYSIOLOGY

subsequently upon the bones of the skull. It is very likely to occur in
children who have rachitis, or "rickets."

By a foramen in the arachnoid membrane, the ventricular cavities and
central canal communicate with the subarachnoid space, allowing cerebro-
spinal fluid to flow through all of these parts. (See p. 281), Arachnoid.

Surgical note. — Because of this, the operation of lumbar puncture may
relieve the pressure of hydrocephalus.

A similarity in structure and arrangement of parts is plainly evident in
the brain and spinal cord. Recall the cord — a collection of nerve fibers,

FIG. 195. — THE VENTRICLES, SHOWING BASAL GANGLIA IN THE FLOOR OF THE
LATERAL VENTRICLES. — (Hirschfeld and LeveilU.)

a, Anterior portion of corpus callosum; b, caudate nucleus; c, location of lentiform
nucleus; d, optic thalamus; h,i, quadrigeminal bodies; g, third ventricle; o, fourth
ventricle; p, medulla. The fifth ventricle is in front of e.

the greater number running up or down, but with many passing from one
side to the other; a central canal surrounded by collections of "gray matter";
two lateral halves connected by transverse commissural fibers.

These parts may all be traced in the brain. The central canal extends
through the medulla and pons into the cerebrum, expanding into a general
ventricular cavity. Gray matter (ganglia) lies close to this canal, even pro-
jecting into it. The white fibers are here, but they diverge on every side, and
many take new directions; also the halves of the brain are connected by
ransverse (commissural) fibers (the corpus callosum). The brain has one

THE DURA MATER 305

part not found in the cord (and a most important part), viz., a covering of
"gray matter," or cortex.

THE MEMBRANES OF THE BRAIN

These are three in number, the pia mater, arachnoid, and dura
mater, like those of the cord, and continuous with them.

The pia mater fits closely to the brain, following all convolu-
tions and uneven surfaces; it is necessary to the life of the brain, as
periosteum is to bone, and for the same reason — it bears the blood-
vessels which nourish it.

The arachnoid lies close to the pia but stretches across the
furrows, leaving subarachnoid spaces for cerebro-spinal fluid as in
the spinal cord. The largest spaces are at the base of the brain
where the greatest irregularities of surface are found.

The dura, firm, white and tough, covers the others loosely and
lines the entire skull, taking the place of periosteum. It has a
number of meningeal arteries branching in its substance, for its
own nourishment and the nourishment of the skull bones (since it
is their internal periosteum) . It sends layers between the large
divisions of the brain — one between the hemispheres of the cere-
brum is called the falx cerebri, and one stretched over the cere-
bellum is called the tentorium cerebelli. They support the weight
of portions of the brain in different positions of the head.

The dura also presents several large veins called sinuses which
collect the blood from the brain. The largest are the sagittal
(longitudinal) running from front to back in the median line, and
the two transverse sinuses (lateral) right and left which end in the
internal jugular vein at the jugular foramen.

Surgical note. — The transverse or lateral sinus lies partly in a deep
groove on the mastoid bone (sigmoid groove) and this adds to the gravity of
operations in the mastoid region.

Clinical note. — Inflammation of the membranes is meningitis. When
affecting the dura it is pachymeningitis; when it is of the pia and arachnoid,
it is leptomeningitis.

THE CRANIAL NERVES

There are 12 pairs of cranial nerves. They are seen at the
base of the brain and leave the skull through various foramina in

306

ANATOMY AND PHYSIOLOGY

the cranial bones. Some are nerves of motion, some of sensation
and some are mixed (Fig. 196). They are named as follows:

1. Olfactory. 7. Facial.

2. Optic. 8. Acoustic or auditory.

3. Oculo-motor. 9. Glosso-pharyngeal.

4. Trochlear, or pulley nerve. 10. Vagus, or pneumo gastric

5. Trifacial, or trigeminus. n. Spinal accessory.

6. Abducens.

12. Hypoglossal.

First, olfactory

'— Second, optic

Third, oculo-motor
Fourth, pathetic

(trochlear)
Fifth, trifacial
Sixth, abducens
Seventh, facial
Eighth, auditory

Ninth, glosso-pharynxal

Tenth, vagus

Eleventh, spinal accessory

Twelfth, hypoglossal

FIG. 196. — BASE OF BRAIN AND CRANIAL NERVES, SHOWING RELATION OF THE PONS
MEDULLA, AND CEREBRUM. — (Monat and Doyen; Brubaker.)

The first, or olfactory (Fig. 196), is the nerve of smell,
sensory it is traced toward the brain.

Being

Minute nerves from the upper part of the nasal mucous membrane
(olfactory region), pass up through the sieve-like plate of the ethmoid bone and
enter the olfactory bulb; from the bulb, a soft band of fibers called the olfactory
tract proceeds to the brain; most of them finally reach the temporal lobe,
where they end in the center for the sense of smell, or olfactory center.

The second, or optic (Fig. 197), is the nerve of vision. It
begins in the retina.

The retinal fibers are gathered to form the nerve, which passes through the
optic foramen into the cranial cavity. The two optic nerves meet above the
body of the sphenoid bone and most of the fibers cross each other there

THE TRIFACIAL NERVE. 307

forming the optic commissure (or chiasm), and then proceed to certain ganglia,
from which the visual impressions are conveyed to the visual centers of
the occipital lobes. (Fig. 194, 16, optic chiasm.)

The third, or oculo-motor (Fig. 197), is the mover of the eyes.
It proceeds from the base of the brain and enters the orbit, to sup-
ply four of the muscles of the eyeball, and also the elevator of the
upper lid. (Eye muscles thus supplied: Superior, inferior, and
internal recti, and inferior oblique. See p. 343, orbital muscles.)

By the action of the first three the eye is turned upward, downward and
inward; the inferior oblique turns it upward and outward.

& 7 to «•

FIG. 197. — NERVES or THE ORBIT.

i, Optic nerve; 2, Oculo-motor (3d); 5, abducens (6th). Other figurer mark various
branches. 10, Ciliary ganglion. — (Sappey.)

The third nerve supplies also the circular fibers of the iris "which
contract the pupil of the eye, and the accommodation muscle — by
which the eye is focussed for viewing objects at different distances.

The fourth, or trochlear nerve, is so called because the tendon
passes through a loop of fascia and bends around like a rope on
a pulley or trochlea. It supplies the muscle which rolls the eye
downward and outward (the superior oblique muscle).

The fifth, or trifacial (trigeminal), is the great sensory nerve
of the face, nose and throat. Some motor fibers for muscles of
mastication accompany the sensory fibers and the nerve is
described as having two roots; sensory and motor.

The sensory root has a large ganglion, semilunar (or Gasserian) ganglion,
and in front of this it is in three divisions, called the ophthalmic, maxillary,
and mandibular nerves. The ophthalmic nerve lies in the orbit ; it is the nerve
of sensation of the structures contained therein; also of the eyelids and side
of the nose. The maxillary nerve appears at the infraorbital foramen. It
is the nerve of sensation for the upper teeth and the cheek and temple. The

308 ANATOMY AND PHYSIOLOGY

mandibular nerve is in the infratemporal fossa, and is the nerve of sensation
for the lower teeth and structures of the lower jaw. The motor root Joins this
branch to supply the muscles of mastication.

The nerve of the sense of taste, called the lingual (or gustatory), accom-
panies the mandibular nerve, from the anterior two-thirds of the tongue.

Surgical notes. — Facial neuralgia is sometimes so severe and intractable
that the semilunar ganglion is removed by the surgeon. This interferes with
sensation of the face, but not with motion.

Three sensitive points on the face where three sensory branches of the
trifacial pass through foramina are: the supraorbital foramen, for the supra -

FIG. 198. — THE DISTRIBUTION or THE THREE DIVISIONS OF THE FIFTH NERVE. —

(Leidy.)

orbital branch of the ophthalmic; the infraorbital foramen for the infra-
orbital branch of the maxillary; the mental foramen for the mental branch
of the mandibular. Section of these nerves is sometimes done for facial
neuralgia.

The sixth, or abducens, is «a motor nerve, supplying the
external rectus muscle, which turns the eye outward, or abducts
it

The seventh, or facial (Fig. 199), is a motor nerve. It passes
through the channel in the petrous bone called the facial or
Fallopian canal (which brings it close to the middle ear). Emerg-
ing from the skull it passes forward through the parotid gland,
and divides into many branches supplying all the muscles of
expression.

ACOUSTIC NERVE

3°9

Clinical note. — If this nerve is paralyzed, the side of the face supplied by
the injured nerve droops and is useless, and the eye fails to close. The face
will be drawn toward the «w-injured side by muscles supplied by the opposite
nerve; this is plainly seen if the patient smiles, or attempts to whistle.

The eighth, or auditory (acoustic), is a sensory nerve. It has
two portions — the cochlear, or proper nerve of hearing, and the
vestibular, or nerve of equilibration. Both pass from the internal
ear through the internal auditory canal to the medulla. (See p.
333, Nerves of the Internal Ear.)

FIG. 199.
The figures mark the branches of the seventh or facial nerve. — (Holden.)

The ninth, or glosso-pharyngeal, is a mixed nerve. The motor
fibers pass from the medulla through the jugular foramen and
supply the muscles of the tongue and pharynx, as its name suggests.
The sensory fibers.convey sensations of taste from the tip and back
part of the tongue. Bitter things are especially appreciated by the
glosso-pharyngeal.

The tenth, or vagus (pneumogastric), is a mixed nerve. It is
traced from the medulla through the jugular foramen.

Branches. — Laryngeal to larynx; pharyngeal to pharynx; car-
diac to the heart; pulmonary to the lungs; and others, indirectly,
to the stomach, liver, spleen, and intestines.

It regulates the action of the heart and the act of swallowing;

3io

ANATOMY AND PHYSIOLOGY

it is the sensory nerve of the air passages from the larynx down,
and of the alimentary tract from the pharynx down.

The eleventh, or spinal accessory, is traced from the medulla
through the jugular foramen, with the ninth and tenth. It
supplies the sterno-mastoid and trapezius muscles with motor
nerves. (A portion of it is accessory to the vagus.)

The twelfth, or hypo-glossal (under the tongue), supplies the
muscles of the tongue and those connecting it with the jaw and
hyoid bone; also the ribbon muscles in front of the neck.

Summary

The nerves of the cerebro-spinal system are distributed to
all voluntary muscles, and to all sensitive structures, as skin, mucous
membranes, lining of joints, and periosteum. They are the nerves
of conscious life.

CRANIAL NERVE SUPPLY TO CERTAIN MUSCLE GROUPS

Region.

Muscles.

Name.

Head.

Neck, lateral. . .
Neck, posterior.
Neck, anterior. .

Pharynx.
Larynx.

Esophagus

Pharynx and Larynx

Of scalp and face

Of tongue

Of mastication — temporal,
masseter, buccinator, two
pterygoids

The digastric assists in mas-
tication

Of the orbit — inferior ob-
lique, levator palpebrae, su-
perior rectus, inferior rectus,

internal rectus

external rectus

superior oblique

Sterno-mastoid.

Trapezius

Ribbon muscles, also the
tongue

Facial, or yth.
Hypo-glossal, or i2th.

Trigeminal, or 5th.
5th and 7th.

Oculo-motor, or 30^.
Abducens, or 6th.
Trochlear, or 4th.

S. accessory, or nth.
Hypo-glossal, or i2th.

Vagus, or loth.

Have also fibers from Glosso-pharyngeal,

9th.

or

Certain associated movements of the orbital muscles are of interest.
The central connections are so arranged that the external rectus
of one eye and the internal rectus of the other move together;

CEREBRAL LOCALIZATION

both eyes turn in the same direction — right or left. The two
internal recti, guided by a convergence nucleus, act together when
the eyes are directed toward a near object. At the same time
the pupil narrows and the ciliary muscle seeks to adjust the
range of vision (see p. 338).

FUNCTIONS OR PHYSIOLOGY OF THE BRAIN AND
CRANIAL NERVES

The cerebrum presides over all conscious acts, and recognizes
all sensations. The anterior portion of the frontal lobes is said
to be the region of mental activity or the seat of the intellect.

CONCRETE CONCEPT

FIG. 200. — THE AREAS AND CENTERS OF THE LATERAL ASPECT OF THE
HEMICEREBRUM. — (C. K. Mitts.)

The cerebrum not only is the seat of volition, directing the
purposive movements of the body, but it also exerts a controlling
force, both accelerating and inhibitory, upon many reflex acts
which originate as involuntary in their nature. The partial con-
trol of respiratory movements has been already alluded to; laugh-
ing, weeping, micturition, defecation, and many other acts may be
included in the same class.

Cerebral Localizations. — Connections between cortical areas
and certain parts of the body have been noted, and their control

312 ANATOMY AND PHYSIOLOGY

over those parts has been demonstrated (Figs. 200, 202). Among
them are the centers for face muscles and for the upper extremity, in
the anterior central convolution; the centers for articulate speech
in the lower convolutions of the frontal lobe. Likewise the centers
for the special senses are fairly well known — as for vision and
memory in the occipital lobe; for taste in temporal; for touch in the
parietal; and for hearing and smell in the temporal and frontal.

These centers are all connected directly or indirectly, by a
complicated system of association fibers (Fig. 201), so that by their
various impressions and nerve impulses they are constantly acting
with or upon each other.

Illustration. — The faculty of speech implies many previous
mental acts. The mind must know and recall the names of things
in order to mention them; it must have seen or heard things in
order 'to describe them and to have learned the words which ex-
press these conceptions. It may do all this and still be silent,
until these many factors are brought to work together under the
influence of the center for articulate speech which, as seen in the
diagram, is in close connection with those for the larynx, tongue
and face muscles. It is this center which determines when these
muscles shall be used for speaking instead of for other purposes.

The first use of the faculty of speech probably represents the attempt to
reproduce a sound; next the impression of something seen, itself having a
sound of its own or a name. Gradually a feeling may come to find expres-
sion and so on through the endless line of impressions and memories, the
education of the speech-controlling center goes on; auditory, visual, sensory-
motor and other centers all contributing to this end.

This is one illustration from many which might be cited, of
the value of association fibers. In general terms it may be stated
that the most highly organized brain has the greatest number of
association fibers, whereby the intellectual faculties of judgment,
reasoning and the will are developed.

The centers which govern skeletal muscles belong to the convolutions
marked motor and cutaneous in Figs. 20x3 and 202. Tracing from below
upward — the larynx, tongue, face, hand, arm and shoulder, foot, leg and
thigh are represented on the lateral surface, in the central convolutions border-
ing the Rolandic fissure; while other thigh centers and those for trunk, are
found on the medial surface bordering the longitudinal fissure.

Note that a large portion of the cortex is devoted to complex

THE CEREBELLUM

313

activities based upon mental pursuits and the acts or states of
mind connected with them.

Clinical notes. — These several localizations furnish a guide to the under-
standing of various disturbances of the nerve system, since irritation of a
given area may cause disordered muscle action in the part which it controls,
or, by pressure (as in hemorrhage or apoplexy) the power of motion may be
lost (paralysis). The same symptoms may follow softening of the cerebral
tissue, the growth of tumors, etc. By carefully observing the condition of
the muscles affected, one can often determine the location of a brain lesion.
Disturbances of hearing, vision, sensation, etc., likewise indicate the seat of
disease or injury.

FIBRM PROPRIJE

SUPERIOR LONGITUD-
INAL FASCICULUS
STRIA TERMINALS »
OF THALAMUS

CINGULUX

UXCINATE
FASCICULUS

INFERIOR LONGITUDINAL FASCICULUS

FIG. 201. — ASSOCIATION FIBERS. — (Morris?)

The function of the cerebellum is to associate or coordinate
the actions of muscle-groups for the accurate performance of
special movements. This is most conspicuously shown in
maintaining the equilibrium of the body, whether standing or
walking. Injury to the cerebellum results therefore in vertigo
and dizziness, in loss of the power to keep one's balance, and of the
ability to walk without staggering.

The medulla oblongata contains many important governing
centers. Among them are the circulatory and the respiratory
centers; these are situated near each other and together they

314

ANATOMY AND PHYSIOLOGY

constitute the "vital knot." Consequently this part of the nerve
system presides over processes of the body which are necessary
to life itself, and when one remembers that the motor and sensory
fibers which connect the brain and cord all pass through the
medulla, it is easy to understand that injury here produces far-
reaching results.

The pons varolii is associated with the medulla in its cranial
nerve connections; most of its fibers are conducting paths between
the other parts which lie in the cranial cavity.

FIG. 202. — THE AREAS AND CENTERS OF THE MESIAL ASPECT or THE HUMAN

HEMICEREBRira. — (C. K. Mills.)

The cranial nerves connect parts of the head and face, also
certain muscles of the neck, with the brain. Through the vagus
(or pneumogastric) nerve — the heart, lungs and digestive organs
possess cranial connections.

The vagus nerve and action of the heart. — The nerve muscle
action of the heart is peculiar to itself both in structure and
function. The fibers of its tissue, or myocardium, are without
sarcolemma and entirely involuntary in action. Again, although
involuntary, they are striped', they are also short, broad and
branched to form a muscle network — just such a structure
as will insure vigorous action within a limited range of motion.
This action is probably to a large degree independent, since

THE VAGUS NERVE AND RESPIRATION 315

the heart possesses ganglionic centers in its own substance from
which it is supplied directly with nerve force. This rhythmic
and apparently independent action is regulated by the inhibiting
or restraining influence of the vagus nerve upon the cardiac nerves.
When from any cause the heart is over-stimulated the vagus
fibers of the cardiac plexus slow it down, thus guarding it from the
exhaustion which follows overwork. The vagus also inhibits
over-action of the vaso-constrictors preventing excessively high
blood pressure. Therefore, it is an important agent for preserving
the balance of force to be exerted between the heart and blood-
vessels.

The vagus and the process of respiration. — This process is
modified by the vagus nerve, probably through its influence upon
the respiratory center in the brain. The digestive organs (from
pharynx down) contain vagus fibers; their function is not perfectly
understood, they are probably sensory.

CHAPTER XXII

THE SYMPATHETIC DIVISION OF THE NERVE
SYSTEM

We have thus far considered those nerve actions which are
associated with consciousness. Although some may be performed
in a purely reflex manner, all may be exercised voluntarily.

The Sympathetic Division is concerned with involuntary
processes only. Nerve stimulus between the central nerve system
and internal organs, and to all involuntary muscle fibers, is con-
veyed through sympathetic neroes.

The nerve tissues of this division are mostly gray, a large
majority of the fibers being non-medullated, that is, they have no
white sheath. This division of the nerve system consists of many
ganglia connected together with nerve trunks, and of nerves which
connect the ganglia with various organs.

About twenty-two pairs of sym-
pathetic ganglia are arranged in two
chains situated at the sides of the
vertebrae, and connected below in
£.0, front of the coccyx. These are the

FIG. 203.— TERMINATIONS OF vertebral or central ganglia (Fig. 204).
GLAND~ The Pre-ve™bral ganglia are situ-
A. Cells of the parotid gland of ated in tlie cavities of the body—
a rabbit. B Cells of the mam- thoracic, abdominal and pelvic; these

mary gland of a cat in gestation.

— (Doyon and Moral.) are intimately connected with the

viscera.

The vertebral ganglia are named according to their location.
They are cervical, thoracic, lumbar, sacral and coccygeal. They
all receive communicating branches from spinal nerves, and send
gray fibers to join spinal nerves and enter the spinal cord. (Gray
and white communicating branches or rami communicantes.}

The branches or nerves belonging to these various ganglia in-
terlace in close networks, forming plexuses which follow the course
of arteries, supplying their walls and the viscera to which they
run. They also supply the cells of glands.

316

SYMPATHETIC GANGLIA

317

Spinal accessory nerve

CERVICAL
PLEXUS

COCCYGEA
PLEXUS

FIG. 204. — LEFT SYMPATHETIC GANGLIA SHOWING COMMUNICATIONS WITH SPINAL

NERVES.— (Testut.)

318 ANATOMY AND PHYSIOLOGY

Special branches from cervical ganglia accompany arteries to
the head, larynx, pharynx, thyroid body, and heart.

Special branches from thoracic ganglia accompany arteries to
lungs and esophagus in the thorax; stomach, liver, spleen, and
other viscera in the abdomen. (The branches passing through the
diaphragm to the solar plexus and abdominal viscera are called
splanchnic nerves — three on each side.)

Special branches from lumbar ganglia accompany arteries to
kidneys and pelvic organs.

Special branches (or nerves) from the sacral ganglia accompany
arteries to the pelvic organs.

The most important plexuses are the cardiac and the pulmon-
ary in the thorax, the celiac (solar) in the abdomen, and the hypo-
gastric in the pelvis (Fig. 205).

The cardiac plexus lies underneath and behind the arch of the
aorta. Its branches supply the heart and lungs, following the
coronary and pulmonary arteries.

The celiac (or solar) plexus is in the abdomen, in front of
the aorta, at the beginning of the celiac artery. It contains two
large ganglia — the right and left celiac (semilunar) ganglia. This
plexus controls the vessels and the muscular coats of the abdominal
viscera; it has been called the abdominal brain. Thus it may be
understood how a severe blow over the plexus would produce a
very widespread and serious result.

The hypo-gastric plexus is in front of the fifth lumbar vertebra
and divides to form the right and left pelvic plexuses, which are
distributed to all of the pelvic viscera (along with branches from
the sacral ganglia and lumbar-spinal nerves).

Notes. — Cardiac nerves from the cervical ganglia descend to the thorax,
entering the cardiac plexuses and supplying the heart and lungs. Certain
branches from the thoracic ganglia form splanchnic nerves which descend to
the abdomen, entering the celiac plexus and celiac ganglia, and supplying
digestive organs. Certain nerves from the lumbar ganglia descend to the
hypo-gastric plexus to enter the pelvic plexuses, supplying pelvic organs.

FUNCTIONS OR PHYSIOLOGY OF THE SYMPATHETIC

NERVES

The work of organs supplied with sympathetic nerves is per-
formed involuntarily and unconsciously save in its results. Vis-

SYMPATHETIC PLEXUSES

319

fa/vital nerve

Piata aiovtVertebral off.
Plant about Sulclaviart a.

Dioracit nerve J.

S^ -[Connections with Vayus £ Gl

tojbrnt P/iaryttyeal plexus

.Superior

.Middle \ Cardiac nerves

, Connections toifA Vagus and
''\ Recurrent lartte

-> 2ef( Pulmonary plexut
CARDIAC PLEXUS

IV
I
Coccyyeal neroe

Mdominal Aortic plexu»

mPOCASJRIC PLEiUS

VUM///O? Coccyyeum impar

FIG. 205. — PRINCIPAL GANGLIA AND PLEXUSES OF THE SYMPATHETIC SYSTEM. —

(Morris.)

320 ANATOMY AND PHYSIOLOGY

ceral muscles, secreting cells, vessel walls, are all under the immediate
domain of the sympathetic ganglia and nerves, whose motor and
sensory fibers are parts of the great nerve system of the body,
through communicating branches.

Certain facts indicate a communication between the brain and
sympathetic nerves, for instance, the thought of food causes a flow
of saliva; think of a lemon — salivary cells are stimulated. Fright
or anxiety may inhibit or prevent the secretion of saliva; or inter-
fere with digestion through a similar effect upon other digestive
fluids; and it is well known that the secretion of milk is greatly
modified by mental or emotional influences.

So with general vaso-motor action. We all know the blanched
face of fright or mental shock; the flush of joyous excitement; or
the blush of embarrassment. All of these are sympathetic reflexes
of psychic origin. In the case of secretion of digestive fluids, the
psychic flow follows the thought of food at once; after that comes
the secretion caused by the presence and contact of food in the
different parts of the alimentary tract.

Again the effect of vaso-motor action may be seen when intense
cold is applied to the skin. The cutaneous vessels contract, the
blood is driven out, the skin becomes white. The opposite condi-
tion is caused by heat — the vessels dilate, the blood flows in and
the skin is red.

By alternate action of the two kinds of vaso-motor nerves
(vaso-dilators and vaso-constrictors] , the blood supply is adapted to
special and varying needs of different parts of the body, and the
balance of pressure preserved in their vessels.

When an organ has work to perform its vessels dilate and the
necessary blood is supplied. When the work is finished the vessels
return to their usual size (their vessel tone being restored by vaso-
constrictors).

The process of digestion, for example, requires that there should
be much blood in many organs; the same is true of general muscular
exercise. Consequently, to exercise violently after a full meal is a
mistake, because the muscles would deprive the digestive organs
of the extra blood which they need, and an attack of indigestion
might follow; at best, digestion would be delayed. It would be
better to delay the exercise.

Many examples might be given and will probably occur to the

FUNCTIONS OF NERVOUS SYSTEM 321

mind of the student, of the interactions of different parts of the
sympathetic system.

These are the processes which must go on more or less continu-
ously. Some may be suspended temporarily, as gland secretions,
or digestion, or the formation of excretions, but they never entirely
cease without causing the death of the individual.

SUMMARY

The sympathetic nerves supply all involuntary muscles, the
coats of blood-vessels and the cells of secreting glands. They are
the nerves of unconscious life, as the cerebro-spinal nerves are the
nerves of voluntary and conscious life.

SUMMARY OF THE FUNCTIONS OF THE NERVE SYS-
TEM AS A WHOLE

We have now concluded the study (briefly) of the entire nerve
system, and we have seen how intimately its various parts are con-
nected. Only through a knowledge of these connections can the
functions of the system be understood.

It must be remembered that all parts of the head and body
have at least two central representations.

Sensory nerves (representing visceral muscle, certain mucous
membranes, etc., and sense organs), enter the cord and proceed as
far as the posterior horns, whence another cell body and its axon
receive and carry the impulse to the cortex of the brain.

Motor cortical cells of the brain prolong their axons (nerve fibers)
only as far as the cord (the medulla oblongata is the upper portion
of the cord). There they meet certain other cells in the anterior
horns, where their message is taken to be carried by these second
axons to skeletal muscles.

Different parts of the spinal cord are associated one with
another by conduction fibers, and the cord is connected with the
brain above by many more, running upward or downward through
the medulla and pons. (On the inferior surface of the brain we
see these fibers as crura or peduncles of the cerebrum and cere-
bellum; they are finally connected with the gray cells of the
cortex.)

322 ANATOMY AND PHYSIOLOGY

In the spinal cord and its nerves we find the apparatus for reflex
action which appears in so many phases — as muscle contraction,
muscle tone, vessel tone, etc. The spinal cord, then, is a great
reflex center, a conducting pathway, and an organ of coordination of
skeletal muscles.

Included in the medulla are centers for still more important
reflexes: the respiratory center; the cardie-vascular center or center
for heart-action and vessel tone combined; the heat regulating
center; deglutition center, and others. Certain functions which
these centers control may be modified by the will; for example,
the respiratory act — we may take a long full breath or a short and
shallow one; breathe rapidly or slowly, at will. Deglutition is still
nearer to the realm of voluntary movements — only when food
reaches the esophagus, is the act of deglutition purely reflex. (Here
is the- first appearance of unstriped muscle in the digestive tract.)

Going higher we find the cerebellum presiding over the coordi-
nation of conscious and voluntary movements, through its connec-
tion with the cortex of the cerebrum on one hand, and the pons,
medulla and cord on the other. Also upon the cerebellum depends
the maintenance of body equilibrium. For this it is necessary that
the semicircular canals of the internal ear should be normal and in
perfect connection with the cerebellum. Other sensory connec-
tions also contribute to the exercise of this function; for example,
to walk unaided without vision is possible, but no£ in a straight
line; or, to walk with feet benumbed is difficult, more so to stand
motionless; showing that the cerebellum is stimulated to the
coordination by which equilibrium is maintained, by more than
one sort of stimulus, probably by many.

We balance the body in equilibrium without conscious sensa-
tion unless we voluntarily direct our attention to the subject. It
is the disturbance of equilibrium which we feel.

Going still higher, we find in the cerebrum the perfecting of
the plan for bringing the whole sentient and moving organism into
the domain of consciousness and the will. This is by means of
the connections of the cerebrum through the pons, medulla, and cord
and their nerves, with every part of the body from -which afferent
impulses come, and to which efferent impulses may be transmitted.

The importance of these connecting fibers cannot be over-
estimated; without them the body would be a disjointed affair.

NERVES OF SKELETAL MUSCLES
C. B.C.

3*3

P.O..

FIG. 206. — DIAGRAM SHOWING THE RELATION OF SKELETAL, MUSCLE AND NERVE

TISSUES — (G. Bachman.)

f.a. Bones of the forearm representing the skeletal tissue; e.j. the elbow
joint, the fulcrum of the lever formed by the bones of the forearm; W. a
weight acting in a downward direction and representing the passive force of
gravity; sk.m. a skeletal muscle acting in an upward direction and the source of the
active power to be applied to the lever; sp.c. transection of the spinal cord showing
the relation of the white and the gray matter; m.c. a motor cell in the anterior horn
of the gray matter; ef.n. an efferent nerve-fiber connecting the motor cell from which
it arises with the skeletal muscle and contained in the ventral roots of the spinal
nerves; af.n. an afferent nerve-fiber arising from the ganglion cell along its course and
connecting the skin, 5., on the one hand with the spinal cord on the other hand and
contained in the dorsal roots of the nerves; c.s.c. coronal section of the cerebrum

324 ANATOMY AND PHYSIOLOGY

Concerning the reception and originating of ideas, the exercise
of thinking — in other words, intellectual processes — we know
only that these activities certainly depend for their normal
manifestation upon a normal cerebrum. A well-developed cere-
brum has good convolutions and deep furrows, and white fibers
in good connection with its several parts. These indicate mental
power, being of more importance than the mere size of the brain.
The brain of the infant possesses all of the interior parts, as
ganglia, etc., but the cortex is almost smooth. The cortical cells
are immature and many axons have not become sheathed. With
the growth of the child and quickening of the mind, the convolu-
tions and furrows appear and develop; the cortical cells mature
and the white fibers become sheathed. (The brain fiber does not
conduct impulses before its sheath is complete.)

The number of association fibers (Fig. 201) is an index of the
mental power of a brain. Large association areas signify a large
expanse of cortex with power to register, remember and compare
a multitude of sensations from various sources — and the ability
to reason about them and form opinions concerning them.

The sympathetic division of the nerve system is the medium
of communication (through communicating branches) of nerve
impulses between the cerebro-spinal system and the organs con-
cerned in involuntary processes, notably those connected with
nutrition and growth, through control of secreting cells and vessel
tone.

showing the relation of the gray to the white matter; p.c. a volitional or motor cell;
d.a. a descending axon or nerve-fiber connecting the volitional cell from which it
arises with the motor cell in the spinal cord; s.c. a sensor cell; a.a. an ascending axon
or nerve-fiber connecting a receptive cell from which it arises (not shown in the dia-
gram) with the sensor cell in the gray matter of the cerebrum. -The nerve-fibers
which pass outward from the spinal cord to the glands, blood-vessels, and the
muscle walls of the viscera, have for the sake of simplicity been omitted from the
diagram.

CHAPTER XXIII
THE SPECIAL SENSES

GENERAL SENSATION

In studying the structure and functions of the nerve system,
we learn that sensory stimuli are received in every part of the body
by afferent nerves, and conducted to sensory cells in the spinal
cord; there they either evoke a muscle response of reflex character,
or are transmitted by connecting tracts to the brain, where the
result is conscious sensation of some sort: as, for example, of tem-
perature— whether of the surrounding air, or of bodies which we
touch; or of other conditions — whether an object is hard or soft,
wet or dry, rough or smooth, etc., etc. These are common and
definite sensations of external things and by these external sensa-
tions we gain knowledge of the world about us.1

Others there are which are definable in general terms only,
and are not definitely located, although plainly felt. For in-
stance, we are hungry, or thirsty, or tired; after pain we have a
sense of relief, etc., the route for stimulus and response in these
matters is through visceral and vaso-motor nerves and their
spinal and cerebral connections, and by these internal sensations
we gain acquaintance with our individual selves. For example,
hunger is the recognition of a lack of food in the tissues; thirst,
of a lack of fluid. Fatigue is the sensation caused by over-
loading the tissues with waste products of metabolism (fatigue
poisons) .

Other mechanisms in the body are adapted to a more definite
class of sensations, by which we learn to know still more exten-
sively, the world in which we live; these are called the organs of
the special senses.

1 We do not'now refer to cranial nerves in which the arrangement is similar but
more intricate.

325

326 ANATOMY AND PHYSIOLOGY

SPECIAL SENSATION

The special senses are: smell, touch, taste, hearing and sight.
The organs concerned are the nose, the skin, the tongue, the ear and
the eye.

It is understood that all consciousness of sensation is based
upon the final reception of sensory impressions by the brain. So
far as a "sense" may be said to reside anywhere, it resides in the
brain, for without it there are no senses as we know them.

THE SENSE OF SMELL

The nose is the organ of the sense of smell. In the nasal
chambers is a layer of special cells — olfactory cells — supported
by a basement membrane, forming the Schneiderian membrane
(or pituitary membrane). The upper part only of the nose is
the olfactory region. Here the sensory nerves arise which proceed
through the foramina in the cribriform plate or the roof of the
nose, to the brain.

In quiet respiration most of the air passes in and out through
the lower parts of the nasal chambers, diffusing gradually into the
upper parts. Although most odors are readily perceived as soon
as one comes into the atmosphere containing them, a slight odor
is better appreciated by means of an effort to draw the air through
the olfactory region, in other words, a sniff. More of the odorous
particles are thus brought into contact with the olfactory cells, and
the impressions made upon them are transmitted by the delicate
olfactory nerves through the cribriform plate to the olfactory bulbs
and thence by the olfactory tracts to the olfactory center in the
temporal lobe of the brain.

The sense of smell is valued for the pleasurable sensations
which it affords, as an adjunct to the sense of taste, and as a
sentinel to warn us of danger when in the vicinity of irritating or
poisonous gases, etc.

Clinical notes. — It may become greatly impaired in catarrhal affections
of the nasal mucous membrane, and is sometimes lost temporarily or per-
manently after an attack of influenza congestion and consequent dryness of
the olfactory membrane (as in coryza or "cold in the head") always diminish
the acuteness of smell. The degree of development of this sense in lower
animals is remarkable; they readily "scent danger."

MUSCLE SENSE

327

THE SENSE OF TOUCH

The skin and the mucous membrane of the mouth constitute
the organ of the special sense of touch (all mucous membranes
are sensitive to temperature and pain, but only that of the mouth
is sensitive to touch).

The special nerve endings are situated in the deeper layers, in-
cluding the hair follicles, and the papillae. Upon their number
and nearness to the surface depends the
acuteness of this sense. An area covered
by thick layers of epidermis is not so
sensitive as one where it is thin; and vice
versa.

There are several forms of nerve end-
ings: tactile cells, for common sensations,
found throughout the skin in the deeper
layers, hair follicles, and papillae; touch cor-
puscles, also in the papillae and especially
numerous in the palm and finger tips, where
sensation is particularly acute; other forms r—J
in muscles and tendons; others still, for the
perception of heat and cold or temperature
sense, etc., etc. These all belong to the
sensory nerves of the cerebro-spinal nerve
system.

The sense of touch includes many va- <L

rieties of impressions by means of which FIG. 207.— TOUCH-COR-
... ,. , PUSCLE OF MEISSNER AND

we may judge of surroundings, and gam WAGNER.

the necessary knowledge concerning the &. Papilla of cutis. d.
external world whereby we can adjust our- J^S^ &£$£&
selves to its conditions. Several of these touch-corpuscles, g. Cells

i j j • -- AI_ i °f Malpighian layer. —

are included in the term muscle sensa- (From Stirling.)
tions"; they constitute the muscle sense.

By this we become aware of many things, as the direction of
movements of our own bodies, whether active or passive; of the
postures of the body or its parts; (this knowledge we apply to
the maintenance of balance) . Also, by muscle sense we estimate
the degree of force felt by the impact of a moving body, or of a
blow received or given (this last is closely related to the apprecia-

328

ANATOMY AND PHYSIOLOGY

tion of weight). The faculty of stereognosis depends upon the
exercise of muscle sense (it is the recognition of articles by hand-
ling them, thus awakening memories of objects previously known) .
Simple contact evokes no sensation without a certain degree of
pressure; touch and pressure are therefore closely related; with
increased pressure comes the impression of weight. If pressure
is sufficiently increased, pain will be felt, which
is due to the disturbance of nerves more deeply
situated.

Again, a touch imparts also a sensation of
place, the place where it occurs; therefore the
sense of touch includes the place sense.

THE SENSE OF TASTE

Fi The tongue is spoken of as the organ of taste,

TASTE-BUD FROM since it bears the taste buds. The sense of taste
PAPILLAOF A^HILD mav be regarded as a specialization of the sense

The oval struc- of touch and the two mechanisms somewhat
ture is limited to the resemble each other.

epithelium (e) lining

the furrow, en- The nerve endings (belonging to the 5th
upon the adjacent and 9tn cranial nerves) which are developed

connective tissue for this purpose are scattered over the surface
(/); o, taste-pore „ , , . , . ,N . ...

through which the of the tongue, and in (certain of) the papillae,

IS? wUhC?£mmnu- also in the Palate and Palatine arches (possibly
cous surface. — sometimes in the pharynx). They are found in

small oval bodies called taste buds, which are in
direct connection with the gustatory nerves.

In order to excite the nerves of taste, substances must be either
already in solution or soluble by the saliva; a perfectly dry sub-
stance may be felt by the tongue, and its temperature, etc., will be
appreciated, but it cannot be tasted. Although all flavors may
be recognized in all parts of the tongue, some are more keenly
appreciated in one portion than another; for example: the bitter
flavors are more plainly tasted in the posterior region, while per-
ception of sweets is more marked in the anterior parts. The borders
seem to apprehend acids more quickly than the dorsum.

Touch, temperature, and smell are all associated with taste.
If a substance is too hot the sense of taste is overcome by the

THE EXTERNAL EAR 329

sense of pain. Many people who have been deprived of the sense
of smell (by disease or injury) assert that they no longer possess
the sense of taste, or that, if present, it is greatly impaired.

THE SENSE OF HEARING

The organ of the sense of hearing is the ear. It has three
divisions: external, middle, and internal (Fig. 210).

The external ear is that part which is on the outside of the
skull, it includes the auricle and the auditory tube. The expanded
portion, mostly of cartilage covered with skin, is the auricle; the

Fossa -m-fl •t~H— Fossa

Antitragus

Lobule

FIG. 209. — THE EXTERNAL EAR. — (Morris.)

deepest depression is the concha, and the opening at the bottom
of the concha leads to the external auditory canal (or meatus).

This auditory canal is one and one-quarter inches in length,
formed partly by the cartilage of the auricle and partly by the
temporal bone. It curves slightly upward, and then downward
and jorward. It is lined with skin which bears stiff hairs in the
outer portion, and contains the glands which secrete "ear wax"
(ceruminous glands}. It is important to remember the length and
direction of this canal.

The membrane at the end of the canal is called the membrana
tympani, or membrane of the drum. It is a fibrous membrane

33°

- ANATOMY AND PHYSIOLOGY

covered with very sensitive skin on the outer surface, and mucous
membrane within (Fig. 210).

The middle ear is the tympanum, or drum. It consists of a
small cavity in the petrous bone, on the inner side of the membrane
of the drum. Its height is barely half an inch, and the other
measurements are smaller still. It contains the little bones and
forms the beginning of the auditory tube.

The auditory (or Eustachian) tube begins in the wall of the
middle ear and ends as a roll of cartilage opening into the pharynx.

The tympanum is really an air chamber, since it communicates

Semicircular Wax
canals glands

.Drum membrane

Cochlea
Cavity of tym-
panum or
drum

\

Parotid gland

Styloid process

Internal
carotid artery

Auditory tube

FIG. 210. — THE EAR. — (Morris.)

with the throat by the auditory (or Eustachian) tube, and both tube
and tympanum are lined with a continuation of the same mucous
membrane. An opening at the back of the tympanum leads into
the mastoid antrum, and through this, inflammation of the middle
ear frequently extends to the mastoid cavities.

Note. — The mucous membrane of the pharynx is continued
through the auditory tube into the tympanum, and through that
into the mastoid cells. Swelling of this membrane may occlude

THE INTERNAL EAR

331

the tube and thus prevent its normal function, which is the trans-
mission of air to and from the tympanum and the equalization of
air-pressure on the two surfaces of the tympanic membrane,
(the external surface at the end of the auditory canal and the
internal surface within the tympanum).

Clinical. — Certain muscle fibers of the pharynx are so arranged
that in the act of swallowing the auditory canal is opened. This
fact is taken advantage of in passing the Eustachian catheter into
the tube.

Two openings lead from the tympanum to the internal ear —
the oval or vestibular window and the round or cochlear window.

The round window is closed by a membrane called the secondary membrane
of the tympanum. The oval window is closed by a fibrous layer and the base
of the stirrup bone (p. 333).

FIG. an. — BONY COCHLEA.

i. Ampulla of superior semi-
circular canal. 2. Horizontal
canal. 3. Junction of superior
and posterior semicircular canals.
4. The posterior semicircular
canal. 5. Foramen rotundum.
6. Foramen ovale. 7. Cochlea.
— (Brubaker.)

FIG 212. — i. Utricle. 2.
Succule. 3. Vestibular end of
cochlea. 4. Canalis reunions.
5. Membranous cochlea. 6.
Membranous semicircular
canals. — (Brubaker.)

The internal ear is a cavity more deeply situated in the
petrous bone. It is extremely complicated, consisting of semi-
circular canals, vestibule, and cochlea, and well named the
labyrinth. There are three semicircular canals placed at right
angles to each other; the cochlea resembles a snail-shell in form,
and the vestibule is between them.

The cochlea and the vestibule both communicate with the
tympanum, the cochlea by the round or cochlear window; the vesti-
bule by the oval or vestibular window.

The illustration (Fig. 211) shows the shape of the osseous
labyrinth cut from the petrous bone. Observe the three semi-

332 ANATOMY AND PHYSIOLOGY

circular canals each with bulb-like extremity, or ampulla, opening
into the vestibule. (Two are joined together at one extremity,
leaving five openings for the three canals.)

Observe the two windows, round and oval in the vestibule wall,
open in the dried bone, as in the illustration, but closed in life by
the lining membrane of the internal ear.

The cochlea is a spiral canal winding two and one-half
turns about a central stem of petrous bone (the modiolus). It is
divided into three canals or scala, reaching from base to apex of the
spiral. In one of these the membranous cochlea lies; of the two
others, one opens into the vestibule and the other ends at the
round window, separated from the tympanum by the secondary
membrane.

The internal ear has a fibro-serous lining which contains a
clear -watery fluid called perilymph.

Lying in the perilymph and bathed by it is the membranous
labyrinth having all parts and shapes of the osseous labyrinth.

Fig. 212 shows the membranous labyrinth which lies within the
bony labyrinth, surrounded by perilymph. It contains a fluid
called endolymph which bathes the fine nerve-fibers of the auditory
nerves.

Note the membranous semicircular canals, with their ampullae,
membraneous cochlea and the two portions of the membranous vesti-
bule. Within these (called the saccule and utricle), the ampullae,
and the cochlea, the terminal fibers of the auditory nerve are
distributed.

Ossicles. — A chain of three ossicles (or little bones) is sus-
pended across the tympanum — the malleus, incus, and stapes.
The malleus (or hammer) is attached by thehandle to the membrane
of the drum, the incus (or anvil) comes next, and then the stapes
(or stirrup) with its base fitting the oval window of the middle ear.
Any vibration of the membrane of the tympanum is at once trans-
mitted by this chain of bones across the tympanum, to the oval
window.

The base of the stapes occupies the oval window (fenestra ovalis);
its movements are transmitted to the perilymph and through this
to the membranous labyrinth, thence to the endolymph within it
and the auditory nerves.

AUDITORY NERVES 333

Nerves of the internal ear. — There are two distinct mech-
anisms in the internal ear; one for the sense of hearing, the other
to serve as an organ of equilibration. So there are two separate
nerves, included under the one name — auditory. Both are
auditory in the sense of being connected with the ear; both are
purely sensory and both are called into action by the stimulus of
mechanical vibration, but here the likeness ends. They differ
in their terminals and their central connections. We shall speak of
them as the cochlear nerve and the vestibular nerve.

The cochlear nerve is the true nerve of hearing. Its terminal
fibers are found in highly specialized epithelial cells in the mem-
branous cochlea (and one ampulla); there they receive impres-
sions transmitted by the vibrating chain of bones. *

By these fibers the cochlear nerve
is formed. It passes through the
internal auditory canal into the
cranial cavity and disappears in the
medulla. Its fibers end in nuclei
situated in the medulla, from which
the impressions brought by them
are conveyed finally to the auditory
area in the temporal lobe (superior FIG. 213. — BONES OF THE EAR.—
temporal convolution). (Morris.)

The terminal fibers of the vestibular nerve are found in
the special cells within the membranous vestibule and ampulla of
the semicircular canals. From thence they are gathered to form
the nerve; it leaves the petrous bone in company with the cochlear
nerve and enters the medulla. The cortical centers for this nerve
are in the cerebellum. It is not concerned in hearing but is neces-
sary to the power of preserving equilibrium in standing, walking,
etc. The person in whom this nerve has been destroyed cannot
walk steadily and is not subject to seasickness.

The vestibular nerve filaments are thought to be stimulated
when vibrations of the endolymph are caused by changes in the
position of the head. This seems to be established clinically.
Through wide association with other nerves, changes in the
position of the body also affect this nerve. The vestibular nerve
fibers end in nuclei situated in the medulla, from which impressions
brought by them are conveyed to the centers in the cerebellum-.

334 ANATOMY AND PHYSIOLOGY

SUMMARY

The function of the external ear is to gather and direct the sound
waves to the membrane of the tympanum. (The ceruminous
glands and hairs of the auditory canal protect the membrane from
foreign bodies floating in air currents.)

The function of the middle ear or tympanum is to transmit the
vibrations thus caused, by the chain of bones to the oval window.

The function of the internal ear is to receive and transmit these
impressions to the brain (the perilymph and endolymph modify
the force of the vibrations as well as transmit them) . If they are
received by the cochlear nerve, they are conducted to the auditory
area in the temporal lobe of the cerebrum. If by the vestibular
nerve, they are conducted to the cerebellum.

Associated nerves and functions. — Many coordinated move-
ments are associated with the sense of hearing.

Listening causes a local increase of tension in the muscles which
affect the position of the eyes and head; very intent listening is
accompanied by a steadying or stiffening of the skeletal muscle
system, and also an instinctive slowing or stopping of respiration.
A sudden noise at one side causes an involuntary turning of the
head toward the location of the sound.

The associations of the vestibular nerves are very wide. They
include not only the nerves of muscles which move the face and
head, but the pneumogastric or vagus, and centers in the anterior
and lateral tracts of the cord in its whole length, whereby the
muscle-sense nerves of the body are all referred to the cerebellum.
In this manner, many different muscle groups are associated and
coordinated in harmonious body movements which we are under
constant necessity to perform in the common activities of life.

CHAPTER XXIV

THE SENSE OF SIGHT. THE VOICE

The eye is the organ of sight. It is situated in the orbital
fossa resting in a collection of adipose tissue from which it is
separated by the capsule of Tenon. This is a thin fascia surround-
ing the greater part of the eyeball, and making a "flexible pocket"
or lymph space in which the ball can be freely moved. The eye
is a sphere or globe having at its surface three layers called the
coats or tunics of the eye — namely the solera and cornea (fibrous),
forming the outer coat, the choroid and iris (vascular), forming
the middle coat, and the retina (nervous) — the inner coat. They

Retina'

Sciera'

Cornea

Iris

Ciliary processes

Lymph canal
Ciliary muscle

FIG. 214. — A SECTION or THE EYE. — (H olden.)

i, Anterior chamber; 2, posterior chamber. The aqueous humor occupies the two

chambers.

contain three transparent structures — the aqueous humor, crystal-
line lens and vitreous body.

The sclera is the "white of the eye." It is dense and tough,
protecting the more delicate structures within. One-sixth of the
surface of the ball in front is occupied by the cornea instead of
the sclera, and this also is dense and tough, but transparent for
the admission of light. It contains no blood-vessels, but many
tiny lymph-spaces. It is the most prominent part of the eyeball,

335

336 ANATOMY AND PHYSIOLOGY

and its convexity may be seen by looking across an eye from the
side. The junction of the cornea with the sclera resembles the
fitting of a watch-crystal in its case.

The portion of the sclera which is visible when the eyelids are
separated, and also the cornea, are both covered by a thin mem-
brane called the conjunctiva; it is a modified mucous membrane,
bearing blood-vessels which can be seen, especially if a little
dilated.

The choroid. — The middle coat, next to the sclerotic, is neither
dense nor tough, but is made up of fine tissue fibers bearing a
very delicate and close network of blood-vessels. It is the vascular
coat of the eye, and lines the sclera only, not the cornea. Many
pigment cells are contained in the choroid coat, giving to it a
deep brown color so that it makes a dark chamber of the eye.

Sclera

FIG. 215. — THE CHOROID AND IRIS. — (Holden.)

The iris. — There is no choroid behind the cornea. Its place
is supplied by the iris, which resembles in its shape a circular
curtain attached by its edge to the choroid, and having a round
aperture in the center called the pupil or the "star of the eye."
The iris contains a network of fine vessels and pigment cells,
varying in color according to the amount of pigment. (Blue eyes
have least, black eyes most.) It has muscular fibers arranged in
two sets — circular, or ring fibers, and so-called radiating, or straight
fibers. The circular fibers surround the pupil. Thus, when they
contract, as in a bright light, they diminish its size. The straight
fibfers run from the outer border of the iris toward the pupil, and

THE OPTIC NERVE . 337

therefore when they contract they draw upon the margin to enlarge
the opening. Briefly, the pupil is contracted by the circular fibers,
and dilated by the straight or radiating fibers, thus the amount of
light admitted within the eye is regulated.

The retina is the innermost coat, of many layers, within the
choroid. This is a very delicate structure in which are the be-
ginnings of the optic nerve fibers. It is the coat which is essential
to vision — no retina, no vision. The outermost layer of the retina
is the one which contains the rods and cones, or the visual cells.
Like the sclera and choroid, the retina is incomplete in front.
When first exposed to the air (in the dissection of an eye) it is
clear and shining in appearance, presenting an opalescent play
of color with a general violet tinge, due to the "visual purple"
contained in delicate pigment cells.

From the cells in the retina delicate fibers are prolonged and
gathered together to form the optic nerve, which pierces the
choroid and the sclerotic, passes through the optic foramen of
the orbit, and thence back to the brain. The optic disc is the spot
where the optic nerve leaves the retina; it is situated a little to the
nasal side of the center of the retina (Figs. 214, 216). Of course the
optic disc is not a portion of the retina proper, and no sense of
vision is stimulated here. It is rather an area where the nerves
and vessels are transmitted through the other coats of the eyeball.

The macula lutea is a spot in the center of the retina opposite the mid-
point of the normal pupil. In the center of this spot is a depression called
ihefovea centralis which is the center of vision; only the cone-shaped visual
cells are here present.

The vitreous body is glass-like, as its name signifies, both in
appearance and transparency. It consists of a jelly-like substance
contained in a hyaloid membrane within the three coats. It trans-
mits and directs the rays of light to the retina; also it aids in pre-
serving the shape of the eyeball (Fig. 214).

The crystalline lens is situated immediately in front of the
vitreous body, in a shallow depression like a cup on the anterior
surface. It is a double convex lens with a capsule, both perfectly
transparent so that light may pass through, and it is able to converge
the rays of light so that they will fall correctly upon the retina.

The lens is behind the iris, the margin of the pupil resting

22

338 ANATOMY AND PHYSIOLOGY

lightly upon it. It is held in place by delicate fibers which form
a suspensory ligament; this is normally a little tense, exerting a
slight but constant pressure upon the eyeball.

The ciliary muscle is in the interior of the eyeball, around the junction of
the choroid and iris, thus lying a little farther forward than the border of the
lens. By its action it draws the suspensory ligament forward, releasing the
lens from pressure; thus it modifies the shape of the lens; by this arrange-
ment the eye is able to accommodate itself to the different distances of sur-
rounding objects. This is the process of accommodation. To "paralyze the
accommodation" is to make the ciliary muscle powerless, so that the eye
cannot try to see near objects, as it always does unconsciously, in its normal
condition. Atropin will do this.

Clinical notes. — Inflammation of the iris, or iritis, may cause adhesions to

Macula H-r^X jy€<£v '"3 Retinal vessel 3

FIG. 216. — THE RETINA AS SEEN WITH THE AJD OF THE OPHTHALMOSCOPE. — (Morris.')

the lens unless the margin of the pupil be drawn away. This is the reason for
the use of atropin, which weakens the circular fibers while it stimulates the
straight ones, or, in other words, dilates the pupil.

Cataract is a thickening of the lens which makes it opaque and gives it a
milky appearance. The remedy is excision or removal of the lens, after which
a convex lens of glass in front of the eye gives a good degree of vision. A
cataract is in an eye, not over it, and must be taken out, not o$.

Aqueous humor and chambers of the eye. — The space be-
tween the cornea and the lens is partially divided by the iris into
two portions — the anterior and posterior chambers of the eye.
They contain a thin clear fluid, called the aqueous humor, which
floats the iris and aids in preserving the shape of the cornea
(Fig. 214).

Note. — The rays of light which fall upon the retina must first
pass through the media (or structures which direct their course) in
the following order: the cornea, aqueous humor, crystalline lens, and

MYOPIA, HYPEROPIA- 339

vitreous body. Should any one of these media lose its transparency,
vision would be impaired or perhaps lost.

The correct retinal image is the object for which these struc-
tures are designed. In order that this may be formed, the rays of
light which are reflected from a wide area of surrounding objects
must be made to converge and meet on the retina, from which
the stimulus thus received is conveyed to the brain- by the optic
nerve. Rays of reflected light go toward the eye from every
direction and by concentrating those which enter the pupil upon
the retina, a small inverted image is formed which is recognized
by the brain as representing the objects so pictured in their proper
size and position.

This concentration of rays of light is accomplished by the
refractive (or bending) media of the eye: the cornea, aqueous humor,

A

FIG. 217. — MYOPIA. FIG. 218 — CORRECTION OF MYOPIA BY

Parallel rays focus at F, cross and A CONCAVE LENS. — (Brubaker.)

form diffusion-circles; divergent rays
from A focus on the retina. — (Bru-
baker.)

crystalline lens and vitreous body, in order. Each medium refracts
(or bends) the rays more and more toward a common center or
focus. The denser the media or the more convex the surface,
through which the light rays pass, the greater the change in their
direction (the shorter the focus).

In the normal or emmetropic eye the focus is at the retina and
a clear image is formed. In the myopic or "near-sighted" eye it
falls in front of the retina, either because some surface (cornea or
lens or both) is too convex or the eye is too long, and the rays of
light from all except near objects, converge in front of the retina.
The remedy is a concave lens of glass to counterbalance the
excessive convexity or length. (See Figs. 217 and 218.)

In the hyper o pic or "far-sighted" eye, the focus would fall
behind the retina; the surface of the cornea or lens is not convex
enough or else the eye is too short. The rays of light are not
sufficiently bent to meet upon the retina and the remedy is a

340

ANATOMY AND PHYSIOLOGY

convex lens of glass to provide for the lack of convexity. (See
Figs. 219 and 220.)

In the condition known as astigmatism, the surfaces are ir-
regularly curved and they form a distorted image; the attempt to
correct this requires a constant effort which is very injurious to
the eye. The remedy is a lens of glass with counter-balancing
irregularities.

Emmetropia is the condition of the normal eye.

Myopia is near-sightedness.

Hyperopia is far-sightedness. (This is congenital.)

Astigmatism may be described as crooked-sightedness.

Presbyopia is the far-sightedness of age (an acquired condition),
the tissues of the eyeball having lost their flexibility and resilience.

The perception of color, or color vision, has not been quite

FIG. 219. — HYPEEMETROPIA. PAR-
ALLEL RAYS FOCUSED BEHIND THE
RETINA. — (Brubaker.)

FIG. 220. — CORRECTION OF HYPER-
METROPIA BY A CONVEX LENS. —
(Brubaker.)

clearly explained; consequently, we cannot state definitely the
cause of defective color vision, or color blindness. This is not
blindness to all colors, but usually to red or green.

It is supposed that certain different chemic substances in the retina are
peculiarly sensitive to ether vibrations of different degrees of rapidity,
whereby impulses of a corresponding nature awaken in the brain the sensa-
tion of the various colors. In color blindness it is not difficult to imagine
that some of these sensitive chemic substances may be absent, thereby
making it impossible for the eye to perceive the corresponding color stimulus.

Range of accommodation. — By this is meant the distance
from the nearest to the farthest point at which an object can be
seen clearly. One can experiment for one's self with any small
object, as for example, with a pencil. By holding it very near
to the eye and gradually moving it away, the point will be found
where the image of the pencil is clear; this is the near point of
accommodation (punctum proximum of vision). Moving it still

REFRACTING MEDIA OF EYE 341

farther away, a point will be found where it can no longer be seen
clearly. This is the far point (punctum remotum}. The distance
between these points is the measure of the range of accommodation.

RESUME.

The solera is protective; the cornea is protective and refractive.
The aqueous humor preserves the shape of the cornea and flexibility
of the iris and also refracts rays of light. The iris regulates the
amount of light admitted, contracting in strong light and when
viewing near objects. It is relaxed and inactive in the absence
of light. (An active dilatation is caused in certain conditions
through stimulation of the radiating fibers.)

The crystalline lens refracts the rays of light which enter the
eye.

The ciliary muscle, by drawing the suspensory ligament forward,
releases the lens from pressure, so that it becomes more convex
and accommodates light-rays from near objects. (Ordinarily,
the lens, prevented by the ligament from assuming its greatest
convexity, is in the position to transmit light from more distant
objects to the retina.)

The vitreous body preserves the shape of the globe and is also
refractive.

The choroid and iris (uveal tract} constitute the dark chamber of
the eye.

The retina is the sensitive nerve layer.

APPENDAGES OF THE EYE

The eyebrows, resting upon the superciliary ridges, or eleva-
tions caused by the frontal sinuses (p. 21), serve to extend the
protection given by the orbit.

The eyelids (or palpebrae,) attached to the margin of the orbits
are necessary for the protection of the eye. They have five layers,
— skin, smooth and thin; fascia — thin and delicate; muscle — the
palpebral portion of the orbicular muscle; fibrous — containing a
stiff plate of connective tissue, the tarsal plate; and mucous — the
layer which lines the lid (conjunctiva}. .

The conjunctiva (or conjunctival sac} is the sensitive mucous
membrane which is attached to the margins of the lids to line them

342

ANATOMY AND PHYSIOLOGY

and to cover the front of the eyeball. The portion which lines
the lids is the palpebral conjunctiva, that which covers the ball
is the bulbar or ocular conjunctiva.

The tarsal glands are in the tarsal plates; their oily secretion

Superior lacrimal gland
Inferior lacrimal gland —

Ducts from superior
gland

Upper eyelid partly
divested of skin

Upper punctura

Lacrimal sac, near its
fundus

Common duct, formed
by junction of upper
and lower ducts

Lower punctual

Naso-lacrimal duct

FIG. 221. — LACRIMAL APPARATUS. — (Morris.)

prevents the lids from adhering to each other. (They are called
Meibomian glands.}

The angles formed by the extremities of the eyelids are the
medial and the lateral angles (inner and outer canthi). At the
medial angle, each lid presents a small elevation, the lacrimal

FIG. 222. — THE MUSCLES OF THE EYEBALL. — (Holden.)
A small section of the upper eyelid is shown.

papilla, with a minute opening (punctum) where the tears enter a
small canal which leads to the lacrimal sac; from the lacrimal sac
they flow through the nasal duct to the nasal cavity.

The eyelashes, or cilia, are kept soft and flexible by an oily

THE LACRIMAL GLAND 343

substance secreted by their own oil glands in the margin of the
lids. The cilia of the upper lid curve upward, those of the lower
lid curve downward; they never interlace. They guard the eye
from foreign bodies — as coal dust, etc., floating in the surrounding
air.

The space between the margins of the eyelids is called the
inter palpebral slit (palpebral fissure). It varies with the action
of the lids; the opening and closing of the slit is done by the
upper lid mainly, the lower one moving but very little. (Muscles
— orbicularis closes, levator palpebrce opens . (See p. 89.)

Lacrimal gland. — The gland which secretes the tears. It is
situated in the lacrimal fossa of the frontal bone, beneath the
lateral end of the orbital arch, and has several ducts for the dis-
charge of the tears under the upper eyelid. The tears flow across
the eyeball and bathe the conjunctiva, washing away the dust and
other fine particles of foreign substances, which would be injurious
if allowed to attach themselves to the conjunctiva. They are con-
ducted by tiny canals (canaliculi] into the lacrimal sac and nasal
duct (see Fig. 221) thence to the nasal fossa. Being a thin saline
solution they are unirritating to mucous membranes.

Clinical note. — The conjunctiva is supplied with blood-vessels
most of which are invisible except when they become congested.
In active inflammation or conjunctivitis they are so enlarged as to
give the membrane a bright red color.

Motions of the eyeball. — The eyeball is moved by six slender
muscles, which have their origin at the apex of the orbit and their
insertion upon the sclera at a little distance from the cornea.
These are the orbital muscles.

The superior rectus rolls the ball upward. (Third nerve.)
The inferior rectus rolls the ball downward. (Third nerve.)
The internal rectus rolls the ball inward. (Third nerve.)
The external rectus rolls the ball outward. (Sixth nerve.)
The superior oblique rolls the ball downward and outward.
(Fourth nerve.)

The inferior oblique rolls the ball upward and outward. (Third
nerve.)

Clinical note. — If these muscles are well balanced the pupil is
directed straight forward while they are at rest, but if they are of quite
unequal strength the eye will be turned habitually in some special

344

ANATOMY AND PHYSIOLOGY

direction. This condition is called squint or strabismus, or "cross-eye."
It oftenest happens with either the internal or external rectus.

The muscles of the iris and the ciliary body are the ocular
muscles.

Associated movements are of interest in connection with the
eye. The central connections are so arranged that the external
rectus of one eye moves with the internal rectus of the other;
the internal recti of the two eyes act together when they are
directed toward a near object. The act of convergence is asso-
ciated with contraction of the pupil and ac-
commodation. It is easily understood that
fixing the eye upon a near object is not a
simple act : — the circular fibers of the iris,
the ciliary muscle and the internal recti are
all called into action. (The far-sighted eye
is doing this work constantly; it is there-
fore important to reh'eve this strain of
overwork by well-fitted lenses.)

FIG. 223. — INTERIOR OF
LARYNX (LEFT SIDE RE-
MOVED).— (Sappey.)

2, Epiglottis; 5, so-called
"false vocal cord"; 9, vocal
band; 13, thyroid cartilage;
14, arytenoid cartilage.
The other figures refer to
parts not mentioned in the
text.

THE VOICE

The voice, by which we establish most
frequent communication with the outside
world, is a special endowment for the ex-
pression of ideas awakened in conscious-
ness by the senses. It is therefore not
inappropriately considered in this con-
nection.

The larynx is the organ of the voice.

(The larynx, lips, tongue and teeth are the organs of speech.}
A brief description of the larynx is given on page 234, of tongue
and teeth, pp. 132, 35.

The structures which are specially concerned in the production
of the voice, in addition to the cartilages described, are the
vocal bands (also known as vocal cords, and true vocal cords}.
These are stretched across the larynx from front to back, being
attached to the thyroid cartilage anteriorly and the two arytenoid
cartilages posteriorly, thus dividing the cavity into upper and lower
portions (Fig. 223).

ORGANS OF SPEECH 345

The arytenoid cartilages are shaped like a triangular pyramid
with a curved apex. They rest upon the cricoid cartilage and form
with it movable joints having ligaments and synovial membranes.
These are gliding joints. They allow the rotation of the arytenoids
upon the articular facets of the cricoid.

The vocal bands are composed of fibrous and muscle tissue
covered with mucous membrane. The space between them is
the glottis.

Small muscles, belonging altogether to the larynx, control the
position and tension of the vocal bands by their action on the
arytenoid cartilages to which the bands are attached, thus
producing the different tones of the voice as the breath passes
between them. Tense bands and a narrow glottis are necessary for
a high note. Lax bands and a wide glottis are the conditions for a
low note.

Above them are two membranous folds, one on either side,
formerly called false vocal cords.

Note. — It has been generally taught that the voice is caused by vibrations
of the vocal bands, but accurate observations by Miss Alice Groff, of Phila-
delphia, and other investigators, have proved that this is not the case, the
voice-sounds being like those of a horn rather than a stringed instrument.

With the aid of lips, tongue, and teeth, the voice sounds are so
modified that speech becomes possible, and with it the expression
of ideas, and communication between individuals.

The various air sinuses which communicate with the nasal
fossae act as resonance chambers. They give to the voice an agree-
able quality of tone, which is in marked contrast to the sound
produced when the air current cannot enter these chambers, as in
coryza (when the mucous membrane is so swollen as to prevent free
admission, to the sinuses, thus causing the nasal tone).

CHAPTER XXV
THE PELVIC ORGANS

IN THE MALE PELVIS. IN THE FEMALE PELVIS.

The rectum. The rectum.

The urinary bladder. The urinary bladder.

The prostate gland. The uterus.

The ovaries, and uterine tubes.
The vagina.

The Rectum is already described (page 146).

The Bladder is the receptacle and reservoir for the urine and is
situated in the pelvis just behind the pubic bones.

It is described with the urinary organs (p. 246).

In the male pelvis the bladder is in front of the rectum and in
contact with it for a short distance in the lower part. Above this
point the peritoneum dips between the two organs forming the
recto-vesical pouch (p. 352, Fig. 227).

The prostate gland is situated at the base of the bladder, im-
mediately in front of the rectum and surrounding the first portion
of the urethra.

In the female pelvis the relations of the bladder are different.
The base is immediately in front of the lower portion of the uterus
and upper portion of the vagina, the urethra lying dose to the
vaginal wall. The peritoneum which dips between the bladder
and uterus forms the utero-vesical pouch.

THE UTERUS AND APPENDAGES

These constitute the internal generative organs.
The appendages are the uterine (or Fallopian) tubes and the
ovaries.

THE UTERUS

The uterus, or womb, is situated between the bladder and the
upper part of the rectum. It is a hollow organ shaped somewhat
like a pear, about two and one-half or three inches long, and one

346

STRUCTURE OF THE UTERUS

347

and one-half inches wide at the larger end, which is called the
fundus and is placed uppermost.

The uterus is composed of non-striated muscles, arranged in
three layers and lined with mucous membrane bearing ciliated
epithelium. Its walls are about three-eighths of an inch thick.
It consists of two portions, the body and the neck or cervix, the
body being a little longer of the two.

POSTERIOR SURFACE OF BODY OF UTERUS

tttero-ovarlan ligament
I OVARY

FALLOPIAN TUBE

Broad ligament-

Infundibulurc
Fimbria
Broad ligament

Vaginal walls

FIG. 224. — UTERUS AND APPENDAGES, POSTERIOR. — (Morris.)

The body is flattened, but is more convex at the back than in
front; the cervix is round.

The tavity of the uterus corresponds to the general shape of the
organ, being triangular in the body and round in the cervix. At
the upper angles of the body are the openings which lead into the
uterine or Fallopian tubes. Between the body and the cervix is
the internal os, the opening at the lower extremity of the cervix
being called the external os, which is bordered by the anterior
and posterior lips. The uterus is covered with peritoneum, except
in front of the cervix.

348

ANATOMY AND PHYSIOLOGY

When the uterus receives an impregnated ovum its function is
exercised in protecting and nourishing the growing embryo until
it becomes a fully developed fetus. The mucous membrane
thickens to form a bed for the embryo, and becomes a part of the
placenta or "afterbirth." The muscle fibers grow in size and

number and the weight
increases from the origi-
nal ounce and a half to
one or more pounds.

The function of the
uterus is concluded with
the expulsion of the
fetus and placenta. It
then contracts rapidly,
and the process of invo-
lution softens and dis-
charges the remains of
tissue which is no longer
FIG. 225.— THE UTERUS. needed. (See p. 358,

Showing cavity and attachment of vagina. — , , . N

Morris.) lochia.)

Position. — The fundus of the uterus is normally inclined somewhat forward, while
the os externum looks downward and backward. If the fundus turns too far
forward this is anteversion; if it inclines backward, retroversion.

A bend may exist where the neck joins the body. This is flexion. When the
body is bent forward, this is anteflexion; when backward, retroflexion.

THE UTERINE TUBES (FALLOPIAN TUBES)

The uterine tubes (Fallopian tubes) two in number (Fig. 224),
extend outward from the upper angles of the uterus; they have a
fibre-muscular structure and are lined with mucous membrane.
Each tube is about four inches long. At the beginning it is only
large enough to allow the passage of a small bristle, but it becomes
larger toward the end, expanding into a trumpet-shaped extremity
called the ifnundibulum, which is fringed or fimbriated, and which
is connected with the ovary below by a slender band (or fimbria).

The function of the uterine tube is to convey the ovum from
the ovary to the cavity of the uterus.

THE OVARIES

The ovaries, two in number, lie on either side of the body of
the uterus, each one being connected to it by a short cord called

OVULATION . 349

the ovarian ligament. An ovary is about three-quarters of an
inch long, a half-inch wide, and shaped like an almond (Figs.
224, 226).

The ovaries are covered with peritoneum (except at the border
where vessels enter and leave).

Structure of the ovary. — A collection of connective-tissue
fibers enclosing many vessels and nerves, and a multitude of little
ovisacs (egg sacs) called Graafian follicles. These follicles are
at first microscopic in size, but when developed they may be seen
by the naked eye. Each one contains an ovum, or egg.

Ovulation. — As the follicle
with its ovum grows in size it
approaches the surface of the
ovary, and when it is mature
the sac ruptures and the ovum
escapes, to be taken by the uter-
ine tube to the uterus, from
which it is discharged through

the vagina, usually with a quan- FIG. 226. — OVARY WITH MATURE

GRAAFIAN FOLLICLE ABOUT READY TO

f
c

BURST— (Ribomont-Dessaignes-Lewis.)

The function of the ovary
(ovulation) begins with puberty, which is the maturing of the
pelvic organs and mammary glands. It is usually established at
about fourteen years of age (earlier in warm climates, later in
cold). From that time the development of at least one ovum
occurs in (about) every twenty-eight days until the menopause is
established.

Menstruation is the periodical discharge of blood from the
uterus. The mucous membrane thickens and sheds its superficial
cells, which are renewed after the flow ceases. This probably
accompanies ovulation. When an impregnated ovum reaches the
uterus menstruation is suspended.

The cessation of menstruation is the menopause or climacteric.
It often occurs at about forty-five years of age and may be as
late as fifty or over. It is followed by gradual atrophy of the
generative organs.

Corpus luteum is the name given to a yellow substance which forms in the
ruptured Graafian follicle. It ordinarily shrinks and disappears within a
month. Immediately after the rupture the follicle fills with blood; this
forms the corpus hemorrhagicum, changes to the corpus luteum and this in

350 ANATOMY AND PHYSIOLOGY

turn is succeeded by a whitish spot called the corpus albicans. If conception
has taken place, the corpus albicans is not formed. The corpus luteum
persists, grows larger and remains present until the end of pregnancy.

The ovary has been included in the list of ductless glands.
Its internal secretion is not discovered, but there is undoubted
clinical evidence that the corpus luteum contains at least one
autocoid substance, since many of the sequelae which follow the
removal of the ovaries are prevented by the use of extract of
corpus luteum (or lutein). By this means the system is supplied
with something of which it had been deprived. (The medicinal
extracts are made from the ovaries of swine.)

THE VAGINA

The Vagina is the muscular canal extending from the uterus to
the surface of the body, where it terminates at the vaginal orifice
(Figs. 165, 224).

It is situated between the base of the bladder in front and the
lower portion of the rectum behind, from which organs it is
separated by connective tissue septa (vesico-vaginal, and recto-
vaginal septa). It curves slightly forward, is four inches long in
its posterior wall and about two and three-quarter inches in the
anterior. It has two layers of muscles, strengthened by fibrous
tissue and lined by mucous membrane which lies in transverse
folds. The columns of the vagina are two median ridges, one on
the anterior and one on the posterior wall, extending throughout
their length.

The vagina is attached to the cervix of the uterus at a little
distance above the external os (about half an inch in front and
three-quarters of an inch at the back); therefore the examining
finger may feel the cervix projecting into the canal. This is the
infra-vaginal portion of the cervix (Fig. 224, 227). The portion
of the vagina which is attached to the cervix is ihejornix (or roof).

Note.— ^The urethra lies close to the anterior vaginal wall, feeling like a
thick cord in the septum between the two canals (the urethra -vaginal septum).

LIGAMENTS OF THE UTERUS

The uterus is sustained in the pelvis by folds of peritoneum
which connect it to the pelvic walls and to the bladder and
rectum. The principal ones are the broad ligaments (Fig. 224).

LIGAMENTS OF THE UTERUS 351

The broad ligaments are folds of peritoneum extending laterally
from the sides of the uterus, like wings, to the sides of the pelvic
cavity. Each fold encloses the uterine tube, ovary, and round
ligament of its own side.

The round ligaments are two muscular and fibrous cords,
which extend from the angle of the uterus lateralward and for-
ward through the inguinal canal, to be attached to the tissues upon
the pubic bone. They aid in preserving the normal position of
the uterus with the fundus forward. This position is still further
secured by utero-sacral ligaments, which connect the junction of
the cervix and body of the uterus with the second and third
pieces of the sacrum, thus holding the cervix back. (They pass
one on either side of the rectum.)

THE EXTERNAL GENERATIVE ORGANS

The pudendum muliebre (vulva). — The name given to the
parts situated in front of the pubic arch of the female pelvis.
They are:

The mons veneris, a cushion of adipose and fibrous tissue in
front of the body of the pubic bone.

The labia majora. — Two folds of skin containing adipose and
loose connective tissue, continuous in front with the mons, and
joined together posteriorly by a fold of skin called the posterior
commissure, about an inch in front of the anus. (The depression
in front of this commissure is the fossa navicularis.)

The space between the labia majora is the pudendal cleft.

The labia minora. — Two folds situated between the labia
majora, about one-half as long, and joined anteriorly in the hood
of the clitoris. B etween them is the space called the vestibule. (They
sometimes unite posteriorly in a thin fold called the frenulum.)

The clitoris. — A small body, somewhat less than an inch in
length, nearly covered by the hood. It contains many vessels
and nerves. The extremity is called the glans of the clitoris; the
hood is normally free from the glans and if adhesions form they
should be separated, since they are a source of nervous irritation.

The vestibule. — A triangular space below the clitoris, and
between the labia minora. In the middle of the vestibule is the
orifice of the urethra, or external meatus.

Below the vestibule is the orifice of the vagina, or vaginal orifice,

352

ANATOMY AND PHYSIOLOGY

partially closed by a circular fold of mucous membrane called the
hymen.

The ragged edges left by rupture of the hymen are called
caruncula myrtiformes. An imperforate hymen is one which
extends entirely across the vaginal orifice, closing it altogether.
A little way, laterally, from the middle of the hymen are the
openings of the ducts of the glands of Bartholin, one on either
side (or vulvo-vaginal glands). Not infrequently they become
infected and swell rapidly, forming an abscess.

THE PERITONEUM OF THE PELVIS

The peritoneum of the pelvis (Fig. 227) is a portion of the
general peritoneum. It lines the pelvic walls, covers the rectum
(except the lowest part) and other pelvic organs, and the floor.

Liver

G astro-hepatic omentum
Stomach ~

Transverse colon

Mesentery

Small intestine

Uterus

Bladder

Epiploic foramen
Pancreas

Duodenum

Transverse meso-colon
Aorta

Rectum

FIG. 227. — DIAGRAM OF A SAGITTAL SECTION OF THE TRUNK, SHOWING THE RELA-
TIONS OF THE PERITONEUM. (Allen Thompson.)

In the male pelvis it dips between the rectum and bladder
forming the recto-vesical pouch.

In the female pelvis it forms a utero-vesical pouch in front of the

THE PERINEUM

353

uterus, and a utero-rectal pouch behind it. It also extends over
the tubes, ovaries, and round ligaments at the sides, thus making
the folds called the broad ligaments, which connect the uterus with
the sides of the pelvic cavity.

The utero-rectal pouch is the pouch of Douglas (or Douglas's
cul-de-sac). It is the lowest part of the peritoneal cavity, ex-
tending down an inch or more behind the vagina.

Note. — The pelvis of the infant (see Fig. 48), is undeveloped
and the pelvic organs lie
partly in the abdomen. As
growth advances they are fi-
nally contained in the pelvis,
at about the fourteenth year.

Perineum. — The name
perineum properly signifies
the parts bounded by the out-
let of the pelvis, but we gen-
erally apply it to the portion
in front of the rectum.

In the female perineum,
the part between the lower
ends of the vagina and rectum
is the perineal body. This is
a triangular body composed
of connective tissue and adi-
pose, the base of the triangle being covered by skin and measuring
about one inch, between the vulva and the anus. It contains
several muscles, some of which are connected with the sphincter ani.

The perineum is distensible, and stretches to a remarkable
extent during labor.

From the male perineum a pouch of skin and fascia is suspended,
called the scrotum. The fascia contains scattered muscle fibers
and is called the dartos.

The scrotum contains the testes which are two in number, the
right and the left. They consist essentially of minute tubes in
which the seminal fluid is secreted, and which open into larger
ones leading to the duct of the testis, or the ductus deferens.

The function of the testis is the formation of spermatozoa (or
spermid) from the cells which line the tubes.
23

FIG. 228. — SHOWING TESTIS AND DUCTUS
DEFERENS SUSPENDED BY SPERMATIC CORD.
— (Holdtn.)

354

ANATOMY AND PHYSIOLOGY

The spermatozoon is the male germinal cell (often called the
sperm cell). It is carried by the seminal fluid through the ductus
deferens to the urethra from which the fluid is discharged.

The duclus deferens passes upward from the testis through the
subcutaneous ring and the inguinal canal, then down into the
pelvis and beneath the bladder, where it runs forward to ente the
urethra.

The spermatic cord. — The testis is suspended in the scrotum
by the spermatic cord, which reaches from the abdominal inguinal
ring to the bottom of the scrotum, and contains the cremaster
muscle. Contraction of the cremaster muscle lifts the testis and
draws it upward in the scrotum (Fig. 228).

Descent of the Testis. — During fetal life the testis is situated in
the abdominal cavity, just below the kidney, but it slowly descends
to pass through the inguinal canal, reaching the subcutaneous ring
at about the eighth month, and at birth it should be in the scrotum.
It may descend more slowly, or may be arrested at any point, but
usually finds its place in time.

In the scrotum it is surrounded by a double sheath of the peritoneum
(tunica vaginalis) which accompanied it, and which became shut off from the
great peritoneal sac as the subcutaneous ring closed around it. It is a serous
sac, having visceral and parietal layers.

In caring for the male infant it is important to note the condition of the
foreskin (or prepuce). This is a fold of skin which covers the glans penis. It
should be sufficiently loose to be easily drawn back, or retracted, in order that
careful cleansing of the parts may prevent accumulations of sebaceous mate-
rial, or smcgma. If this is not done, irritation is caused by ret ained substances
and also by adhesions which are apt to form.

Circumcision is cutting off the foreskin (literally — cutting around).

Hydrocele is a collection of serous fluid in the vaginal tunic of the testis.

Impregnation. — The entrance of the spermatozoon into the
ovum causes impregnation or conception. The spermatozoon
reaches the ovum after passing through the vagina and uterus into
the uterine tube; it is here that conception usually occurs, in an
ovum which has entered the tube on its way to the uterus. The
head (or nuclear part) of the sperm cell unites with the nucleus of
the ovum to form one new or "parent cell." By division of its
substance this cell forms many new ones (all contained within
the wall of the parent cell), each composed of the united original
elements. A series of rapid changes follows and a re-arrangement

THE DECIDUA

355

of the new cells into three layers, from which the different parts
of the body of a new being and the membranes which envelop
it, will develop. When the impregnated ovum reaches the uterus
it finds extensive preparations already made for its reception.
Instead of being washed away by menstrual fluid, it is deposited
in a soft bed of the thickened mucous lining of the uterus which
has developed an increased growth and new features for the
purpose. As this membrane will be discarded after the birth of
the child, it is called a true decidua, or decidua vera (Fig. 229.)

The impregnated ovum becomes attached to the mucous
membrane usually near the fundus (see Fig. 230). This area of

FIG. 229. — THICK-
ENED LINING OF A
PREGNANT UTERUS.

Showing decidua
vera, decidua serotina
and beginning of the
reflexa. — (Dallon.)

FIG. 230. — THICKENED
LINING OF A PREGNANT
UTERUS.

Showing decidua reflexa.
— (Dalton.)

fixation becomes the decidua serotina. A portion of the decidua
vera rises on every side of the ovum and thus forms a third decidua,
the decidua reflexa which finally encloses it. As the ovum grows
and the fetus develops to fill the uterine cavity, the decidua reflexa
becomes fused with the decidua vera and together they are dis-
charged in the lochia. The serotina becomes a part of the placenta.

RESUM£

The decidua vera is the uterine decidua.

The decidua reflexa is the ovular decidua. (Together these two
disappear in the lochia.)

The decidua serotina is the placental decidua.

356

ANATOMY AND PHYSIOLOGY

' Right innominate vein

Superior vena cava
Right pulminary artery

Inferior vena cava

Left branch of portal vein
Ductus venosus

Umbilical vein
Portal vein

Right branch of
portal vein

Umbilical vein
Umbilical arteries

Umbilical artery

Left innominate
vein

Arch of aorta
Ductus arteriosus

Left pulmonary
artery

Descending aorta

[Superior
mesenteric artery

Splenic vein

Superior
mesenteric vein

Inferior
mesenteric artery

Left common iliac
artery

Hypogastric artery

External iliac
artery

FIG. 231. — THE HEART, WITH THE ARCH OF THE AORTA, THE PULMONARY ARTERY, THE
DUCTUS ARTERIOSUS, AND THE VESSELS CONCERNED IN THE FETAL CIRCULATION. — (Morris.)
(From a preparation of a fetus in the Museum of St Bartholomew's Hospital.)

THE PLACENTA 357

The fetus is enclosed in the amniotic sac which is formed by the fusion
of two membranes (amnion and chorion) derived from layers of the original
cell. It is often called "the membranes."

It contains amniotic fluid — a clear saline solution in which the fetus
floats. The placenta is developed in the outer layer of the sac (chorion).

Clinical note. — It is sometimes possible to separate the two layers of mem-
brane to a partial extent.

The placenta is a mass of uterine and fetal blood and lymph
vessels, held loosely together. The vessels of the decidua serotina
are branches of the uterine arteries, which form thinly covered
loops called villi. These are received between similar villi of the
fetal vessels, forming the placenta. The blood of these two sets of
vessels is separated only by the thinnest of membranes, so that
the respiration (or exchange of 0 and C02) of the infant is thus
provided for,1 the impure blood arriving from the fetus by two
arteries (right and left hypogastric) and returning purified to the
fetus by one vein, the umbilical (Fig. 231).

Point of interest. — The function of these vessels is similar to that in the
lungs of extra-uterine life, where the right and left pulmonary arteries carry
impure blood to the lungs and pulmonary veins carry pure blood to the heart.

Note. — The placenta is not within the amniotic sac. The fetal surface is
smooth, a part of the sac itself; the maternal or uterine surface is irregular,
dark red and friable (easily separated into its original masses of vessels and
connective tissue called cotyledons}.

Pregnancy or gestation is the condition in which these proc-
esses are going on. It begins with conception and ends with the
expulsion of the fully developed fetus from the uterus, or
parturition.

The normal duration of pregnancy is 280 days or ten lunar
months. During the first five months the growth is very rapid;
the length of the fetus increases from one centimeter in the first
month to twenty-five in the fifth (about 10 inches). After the
fifth month the growth advances steadily but not so rapidly.
The average length at birth is about fifty centimeters, and the
average weight 2737 grams, or 7 1/3 Ibs.

The growth of the uterus to accommodate the growing fetus
has been alluded to. The great blood supply required for all
these changes is provided by the uterine and ovarian arteries which
are normally very large in proportion to the size of the organs.

1 By processes of diffusion and osmosis as in the lungs.

358 ANATOMY AND PHYSIOLOGY

Fig. 138 illustrates the way in which they are disposed in order
to provide for the increasing area to be supplied and for the
growth of the fetus. Their tortuous course provides for a greatly
increased distribution to constantly enlarging organs without
undue stretching of the vessels.

During the first three or four months (according to different
authorities) the fetus is known as the embryo.

Expulsion of the fetus during the first three months constitutes
abortion; from the fourth to the sixth months, it is called mis-
carriage. After six months it is possible for a strong fetus to go
on developing after expulsion (although exceedingly uncommon
at that date); therefore, from that time until term (the end of 280
days) expulsion constitutes premature delivery. The delivery of
the child is usually preceded by the escape of amniotic fluid.

The quantity of amniotic fluid is about one liter. Its use
is to provide against injury from sudden jars or blows during
pregnancy, to allow freedom of movement on the part of the fetus,
to preserve the flexibility of the skin of the fetus, and at the time
of parturition to aid in the dilatation of the cervix of the uterus
as it fills a pouch of the amniotic sac which is forced down by
uterine contractions.

Soon after the expulsion of the child, the placenta is separated
from its attachment to the uterus by the contracting walls and
later is expelled, with the ruptured and emptied sac.

The placental site is now bare and bleeding. Large blood
spaces or sinuses are still open, left by the detachment of the pla-
centa, although rapidly closing if the uterus becomes well con-
tracted.

Clinical note. — The great advantage of a well-contracted uterus is, that
it guards against two possible dangers: (i) That of hemorrhage from the
open vessels; (2) (and even more serious if possible) that of infection through
this wide open surface. The latter is the reason for such scrupulous care
which is demanded in the nursing of obstetric cases.

The lochia. The combined decidua vera and decidua reflexa
soften, disintegrate and come away from the uterus (with the blood
which is oozing from the interior) as lochia. The discharge is
known at first as the lochia rubra; then, when it is thinner, as the
lochia serosa. Third and lastly; when the disintegrated tissue cells

PLACENTA PREVIA- 359

and leucocytes give the discharge a creamy white appearance, it
is called the lochia alba.

Placenta previa. — Wherever the ovum attaches itself the de-
cidua serotina develops to form the maternal part of the placenta.
Should the implantation of the ovum be so low as to- encroach
upon the internal os, it causes a placenta previa.

Ectopic Gestation. — If an impregnated ovum begins to develop at any point
outside the uterus this constitutes an extra-uterine or ectopic gestation. Men-
struation ceases as in a normal pregnancy and a decidua vera begins to form,
but is often shed at two or three months. Very infrequently the develop-
ment of the ovum and fetus goes on to term, when delivery must be by abdom-
inal section, but the usual course is rupture of the containing part and inter-
nal hemorrhage, necessitating an operation of emergency.

In all extra-uterine or ectopic pregnancies the descriptive name is derived
from the abnormal location, as tubal, ovarian, etc., etc.

The child-bearing age begins at puberty or the time of develop-
ment of the generative organs and the establishment of ovulation
and menstruation. It continues until the climacteric or menopause
which marks the cessation of menstruation.

CHAPTER XXVI

A BRIEF STUDY OF IMPORTANT REGIONS
THE HEAD AND NECK

The scalp. — Observe the larger arteries — the supraorbital in
front, the temporal and posterior auricular at the sides, and occipital
at the back — that their general course is upward toward the vertex,
and therefore a bandage may be so adjusted around the head as to
cut off. the blood supply to a great extent.

The nerves have similar names and take a similar course.

The tense temporal fascia covers the temporal muscle above
the zygoma.

THE FACE

The main artery, external maxillary (or facial), runs obliquely
upward toward the side of the nose; its course is tortuous, so that
the play of the facial muscles will not interfere with the passage
of the blood current. The facial vein is lateral to the artery and
not very close to it. Pulsation of the artery may be felt where it
crosses the lower border of the mandible, about one inch in front
of the angle.

The external carotid artery bifurcates in the substance of the
parotid gland in front of the ear, forming the temporal and internal
maxillary arteries. The pulsation of the temporal is felt as it
crosses the zygoma, and both here and over the external maxillary
on the border of the mandible, the character of the heart's action
may be appreciated while the patient is under the influence of
ether.

The motor nerves (facial nerve) come through the parotid gland
and radiate on the side of the face, transversely toward the nose,
upward toward the eye and forehead, and downward toward the
neck.

Sensory nerves, branches of the trifacial (trigeminus) , appear at

360

STRUCTURES OF THE NECK 361

the three foramina mentioned elsewhere — supraorbital, infra-
orbital and mental — the three particularly sensitive spots in the
front of the face.

Practical note. — The tongue muscles and the floor of the mouth
(mylo-hyoid muscle} are both connected with the mandible.
Therefore, if the jaw be held forward and upward, it will control
the position of the tongue when the muscles are relaxed, as under
ether. Hence, the necessity for this precaution, to prevent the
tongue from falling back into the throat.

FIG. 232. — SUPERFICIAL VESSELS OF HEAD.
THE NECK

The skin of the back of the neck is very tough and the fascia
very dense. These facts account for the pain of inflammation
here, due to the consequent pressure upon the rather numerous
nerves, as in carbuncle.

The spine of the seventh cervical vertebra is always easily felt.
This is the vertebra prominens.

The two sterno-deido-mastoid muscles are conspicuous at the
side of the neck, situated near each other at their origin, and di-
verging above. The thyroid cartilage of the larynx projects in
front — the so-called Adam's apple. The external jugular vein runs
from behind the ear downward toward the middle of the clavicle,
and is covered by the platysma muscle. It is sometimes selected
for the operation of "bleeding,*' or phlebotomy, and the incision

362

ANATOMY AND PHYSIOLOGY

to expose the vein is made across the muscle fibers, because by
their retraction the vessel is well uncovered (Fig. 76).

The sternomastoid and trapezius are the muscles affected in the
commonest form of wry-neck or torticollis, which is usually due to
spasm of the muscles.

THE TRIANGLES OF THE NECK

These are spaces between certain muscles, as follows: In front
of; the sterno-mastoid is an anterior triangle divided by the superior

FIG. 233. — TRIANGLES OF THE NECK.

C, Carotid triangle; M, muscular triangle; O, occipital triangle; S, subclavian
triangle; D, digastric triangle.

belly of the omo-hyoid into two, called the carotid and muscular
triangles ; behind the sterno-mastoid is a posterior triangle divided
by the inferior belly of the omo-hyoid into two, called the occipital
and subclavian triangles.

In the nuscular triangle is the common carotid artery, with the
internal jugular vein on the lateral side of it, and the vagus nerve
behind them both.

In the carotid triangle the same structures are found, but

THE THORAX 363

here the artery divides, forming the external and internal carotid
arteries at about the level of the upper border of the thyroid
cartilage, or "Adam's apple."

Surgical note. — The carotid is called the triangle of election because, since
the vessels are near the surface, the surgeon would naturally choose, or elect,
this place for the operation of ligation. In the muscular triangle the vessels
are more deeply placed and covered by the lower portion of the sterno-mas-
toid. Ligation of the artery would be done here only under necessity, so it
is called the triangle of necessity.

Occipital triangle. — The occipital artery and nerve run through
this triangle.

Subclavian triangle. — Most important structures are sub-
clavian artery and vein, brachial plexus, and phrenic nerve.

Clinical note. — Pressure in this triangle, close to the clavicle, will be felt
by the nerves of the brachial plexus. Pressure downward and backward close
to the sterno-mastoid will compress the subclavian artery against the first
rib. Its pulsation is plainly felt.

Submaxillary triangle. — This is a small space marked off from the carotid
by the digastric muscle. It contains the submaxillary gland and external
maxillary artery.

THE THORAX AND THORACIC VISCERA

The bony thorax is narrow above and broad below, but the
proportions are reversed in the completed human body by the
presence of the large muscles_which connect the upper extremity
with the thorax.

Observe the transverse ridge on the sternum, marking the junc-
tion of the first and second pieces (the manubrium and the body).
The second rib joins the sternum at this ridge (Fig. 234).

The boundaries of the completed thorax are the spinal column
at the back, the sternum in front, and the ribs at the sides, with the
intercostal muscles in the intercostal spaces and the diaphragm in
the floor. It is covered behind by the muscles of the back, while
the anterior serratus is on the side and the pectoral muscles are in
front. The shoulder blades are placed behind the thorax.

The intercostal arteries and nerves are protected from injury by
their position under the borders of the ribs. A stab-wound would
have to be directed upward to reach them.

All muscles which are attached to the ribs are muscles of res-

364

ANATOMY AND PHYSIOLOGY

piration, the intercostals having considerable power, but the dia-
phragm being most important. When it contracts it is depressed,
increasing the depth of the thoracic cavity, while the other muscles
broaden the cavity by lifting the ribs, and thus room is made for
expansion of the lungs in inspiration. As the ribs fall and the
diaphragm ceases to contract, it rises, returning to its dome shape,
and thus the air is pressed from the lungs in expiration. These

FIG. 234. — THORACIC AND ABDOMINAL VISCERA, ANTERIOR. — (Deaver.)

two acts complete a respiration, or an act of breathing, which
occurs normally about eighteen times in a minute. If respiration
is very difficult other muscles are called into play, as in asthma,
when the struggle for breath is so great that " forced inspiration" is
necessary.

The erector spinae muscles are always on duty, to steady the
spine in order that the ribs may have a point of departure.

The cardiac impulse is felt (sometimes it may be seen) between

THORACIC AND ABDOMINAL VISCERA 365

the fifth and sixth ribs, half way between the sternum and the
nipple line.

The mammary gland covers the front part of .the spaces from
the third to the fifth ribs. It lies between layers of the superficial
fascia in front of the pectoralis major muscle.

The superior opening transmits the trachea, esophagus, and
important vessels and nerves. The floor (or diaphragm) has three
openings — one for the passage of the aorta and thoracic duct, one
for the inferior vena cava, and one for the esophagus and vagus
nerves.

The thoracic viscera are the esophagus, trachea and bronchi,
lungs, and heart. The esophagus lies close to the spinal column,
and the trachea is in front of the esophagus, dividing into the large
bronchi, whose branches are the bronchial tubes. The heart and
large vessels are in the anterior and middle part of the thoracic
cavity (Fig. 234).

The heart is wrapped in the pericardium, and each lung is
wrapped in a pleural sac which is placed between the lung and the
chest wall. An incision through that part of the wall which is
bounded by the ribs would pierce the costal pleura and open the
pleural cavity. A wound of the lung would injure the pulmonary
pleura.

The large nerves in the thoracic cavity are the vagi, lying close
to the esophagus, the sympathetic, whose branches form cardiac
and pulmonary plexus, and the two phrenic nerves, right and left,
running down on either side of the pericardium to the diaphragm.

The mediastinum is the space between the lungs. In it all of
the thoracic viscera except the lungs are situated.

THE ABDOMEN, ABDOMINAL VISCERA, AND PERITONEUM

The boundaries of the completed abdomen are the spinal
column and quadratus lumborum muscles at the back, the hip-bones
below, the rectus muscles in front, and the broad fiat muscles at the
side. The diaphragm is its roof. The transversalis fascia lines the
cavity, and the peritoneum is within the fascia, held to it by areolar
tissue called subperitoneal or subserous tissue.

On the anterior surface of the abdomen observe the outline
made by the lower ribs, between the thorax and abdomen, the two
sides meeting in the subcostal angle just below the sternum. The

366

ANATOMY AND PHYSIOLOGY

scrobiculus cortli- »\ pit «i tin- tomach, is a slight depression at
the very point of t.hc :,ul« ostal anjde, caused by a weak spot in the
attachment of the abdominal muscles. If the abdomen is greatly
distended, the depression di:-.appears. The linea alba is between
the two rectus muscles, and the semilunar lines (or linea semi-
lunares) are at the sides of the recti. The transverse lines (linea
transfer see) may be seen when the recti contract.

The subcutaneous inguinal ring is just above the tubercle of the
pubic bone; the abdominal inguinal ring is a half inch above the

'I i|: i.f MI iL, nri i .irlilage
I .,'l;il Ur.l.r

Upper liriti/niil.il |.l,iii'-

Lower horizontal tilanr A, at
level of tubercles of iliac
crcRt

I.OWrr li',n/< nl.i! I'l.inr I',. :il

cvel of ;u/i' n',r ih.it xpinet

Vriliial plane A, from middle
of Poupart'it ligun

Vertical plane B, at outer
IxMilT of rectui (irtni-
ln n.ii line)

Summit of sym|>hysix |nihii

Fio. 235. — DIAGRAM or THE ABDOMINAL REGIONS. — (Morris.)

middle of the inguinal ligament. The conjoined tendon is behind
the subcutaneous ring.

The abdominal muscles and skin are supplied by the lower
intercostal and first lumbar nerves.

The regions of the abdomen are outlined in the following
manner: Imagine a horizontal plane passing through the ab-
domen at the level of the tenth costal cartilage, and another at the
level of the anterior superior spine of the ilium. These would
divide it into three portions — upper, middle, and lower. Then
imagine two vertical planes passing through the middle point of
the inguinal ligament on either side, and dividing each of these
three portions into three regions, making nine in all.

THE PERITONEUM . 367

The middle region is called the umbilical, having the umbilicus
on the anterior surface. Above that is the epigastric, and below it
is the hypogastric. At the sides of the epigastric region are the
right and left hypochondriac. At the sides of the umbilical region
are the right and left lumbar; and at the sides of the hypogastric
region are the right and left iliac, or inguinal.

The abdominal viscera are the stomach, intestines, liver, spleen,
pancreas, kidneys, and adrenal bodies. The great vessels are at the
back. The sympathetic ganglia are at the sides of the vertebrae,
with the celiac and other plexuses situated on the large vessels.

The kidneys are behind all of the other viscera, and the
ureters run down close to the posterior wall of the abdomen on their
way to the bladder.

The receptaculum chyli, or beginning of the thoracic duct, is in
front of the second lumbar vertebra. The inferior vena cava lies on
the right side of the aorta.

The principal organ in the epigastric region is the stomach; in
the right hypochondriac, the liver; in the left hypochondriac, the
spleen. The umbilical region is occupied mostly by small intestines.
The right and left kidneys are in the two lumbar regions, with the
ascending colon in front of the right, and the descending colon in
front of the left kidney. The cecum and appendix are in the right
inguinal region; the bladder, in the hypogastric.

Each region contains portions of several viscera in addition to those named.
Scarcely any organ save the spleen and cecum can be said to belong to but one
region.

The peritoneum is a closed sac of serous membrane like a
water-bag, which is placed between the abdominal wall and
abdominal viscera. It is practically in front of the viscera, and
tucked in around them at the sides. One side of the sac is closely
applied to the abdominal wall, and is called the parietal peritoneum,
while the other side is fitted to the viscera, and called the visceral
peritoneum. Normal peritoneum is perfectly transparent, and the
viscera are plainly seen through the visceral layer. The peritoneal
cavity contains a little serous fluid and nothing else.

An incision in the abdominal wall, including the parietal per-
itoneum, opens the peritoneal cavity. An incision into one of the
organs involves also the visceral peritoneum, with these exceptions:

368 ANATOMY AND PHYSIOLOGY

The posterior surface of the liver.

The posterior surface of the ascending colon. The kidneys.

The transverse portion of the duodenum. The front of the
bladder behind the symphysis. These parts have no serous layer.

The lowest portion of the peritoneal cavity is in the pelvis,
extending down about three and a half inches in front of the
rectum. In the female this is called the recto-uterine fossa, or
pouch ol Douglas. In the male it is the recto-vesical fossa.

The folds of the peritoneum which are connected with the
stomach are called omenta (p. 148).

The folds which connect the intestines to the abdominal wall
are called mesenteries (p. 147).

The folds which connect other organs to the abdominal or pelvic
walls are called ligaments. Those for the bladder are called vesical
ligaments.

The ligaments of the liver are the broad, the round, the coronary,
and the two lateral ligaments, which connect it to the diaphragm
and the anterior abdominal wall.

Sometimes certain little pockets, or fossae, exist in the perito-
neum, behind the different portions of intestine. If a loop or
knuckle of bowel slips into one of these fossae it may press its way
through it and pass behind the peritoneal sac. This is a retro-
peritoneal hernia.

THE ISCHIO-RECTAL FOSSA

This is a space between the ischium and the rectum. It is
filled with loose connective tissue and adipose, and a few vessels
and nerves are therein contained. The skin of the buttock forms
the floor of the fossa; the lower part of the rectum is the medial
wall; the fascia of the obturator muscle forms the lateral wall.

Surgical note. — If infection occur in this region, a very large abscess
might result, the pus burrowing freely in the loose tissues. Ischio-rectal
abscess is often caused by internal fistula.

THE AXILLARY SPACE

The axilla is the armpit. Its shape is that of a pyramid, with
the apex under the shoulder-girdle at the level of the first rib, the
base of the pyramid being the floor of the space and composed of the

STRUCTURES IN AXILLARY SPACE

369

skin and fascia crossing from the thorax to the arm. The walls
of the space are formed by muscles — the serratus (principally) on
the medial wall, covering the ribs; the long tendon of the biceps
in its groove on the lateral wall; the pectoral muscles in the anterior
wall, and the subscapularis, latissimus dorsi and teres major in the
posterior wall.

The importance of this space is due to the large vessels and
nerves, and the lymph nodes, which are found in it. The vessels
are the axillary artery and vein; the nerves are the brachial plexus
and branches. A chain of superficial lymph nodes lies under the
border of the pectoralis major, and a collection of deep ones is
grouped around the large vessels; there are also a few near the
posterior wall.

Axillary artery

THE ANTE-CUBITAL SPACE

A triangular space in front of the elbow-joint

Boundaries. — The brackio-radialis, pronator teres, and an

imaginary line connecting
the two epicondyles.

Important structures. —
Biceps tendon, brachial artery
and veins, median nerve. The

Median nerve
Brachial artery

Lateral cord

FIG. 236. — AXILLARY SPACE.
Axilla laid open by division of anterior
wall.

FIG. 237. — ANTE-CUBITAL SPACE.

Pronator muscle divided to show

ulnar artery.

artery is between the tendon and the nerve, lying on the brach-
ialis muscle. Tendon on lateral side of artery — T-endon, A-rtery,
N-erve. The artery divides here.

24

370 ANATOMY AND PHYSIOLOGY

SCARPA'S TRIANGLE (TRIGONUM FEMORALE)

This triangle is on the front of the thigh. The base is formed
by the inguinal ligament, the lateral border by the upper half of
the sartorius, the medial border by the adductor longus, and the
apex by the crossing of these two muscles on the medial side of
the thigh at about the middle.

Femoral artery
Femoral nerve
Femoral vein

i
i
Deep branch

FIG. 238. — STRUCTURES IN
SCAKPA'S TRIANGLE; PORTION OF
SARTORIUS REMOVED.

FIG. 239. — POPLITEAL SPACE. — (Holden.)

a, Biceps; b, peroneal nerve; c, plantaris;

d, lateral head of gastrocnemius; e, semi-

tendinosus;/, semimembranosus; g, gracilis;

h, sartorius; i, medial head of gastrocnemius.

The most important structures in the triangle are the femoral
artery and vein lying side by side, in a line from the middle of the
base to the apex. The femoral nerve and branches are on the
lateral side of the artery.

Order of structures as they pass under the inguinal ligament.
V-ein; A-rtery, N-erve, the vein being medialward.

INGUINAL AND FEMORAL CANALS 371

HUNTER'S CANAL (ADDUCTOR CANAL)

This is a passage from the front of the thigh around the media]
side to the posterior, beginning at the apex of Scarpa's triangle and
ending in the popliteal space by an opening in the adductor magnus
muscle. The femoral artery passes through this canal, with the
femoral vein on the medial side of the artery. The long saphenous
nerve is sometimes within the canal and sometimes outside it

THE POPLITEAL SPACE

This is a deep diamond-shaped space behind the knee-joint-
Its floor is formed, from above downward, by the popliteal surface
of the femur, the posterior ligament of the joint, and the popliteus
muscle. The boundaries of the upper half of the space are made
by the biceps tendon on the lateral side, and the semitendinosus
and semimembranosus on the medial side. The boundaries of the
lower half are the lateral and medial heads of the gastrocnemius.
These muscles are all very prominent, making the space deep.
The popliteal space owes its importance to the large vessels and
nerves which it contains — the popliteal artery, the popliteal vein,
and tibial and common peroneal nerves. They are all deeply
situated, the artery being the deepest, and are imbedded in adipose
tissue and covered with strong fascia, being thus well protected.

THE INGUINAL RINGS AND INGUINAL CANAL

There is an opening in the aponeurosis of the external oblique
muscle just above the pubic bone, which is called the subcutaneous
inguinal ring, being under, the skin in the inguinal region.

There is an opening in the transversalis fascia, half an inch
above the mid-point of the inguinal ligament. This is called the
abdominal inguinal ring, opening into the abdominal cavity in
the inguinal region. The passage from one ring to the other is the
inguinal canal.

The internal oblique and transversus muscles form the conjoined
tendon immediately behind the subcutaneous ring, and their lower
muscle fibers arch over the canal, forming its upper boundary.

THE FEMORAL RING AND FEMORAL CANAL

The femoral ring (annulusfemorale) is a weak place in the pelvic
wall, under the inguinal ligament, where the femoral vessels do not

372 ANATOMY AND PHYSIOLOGY

occupy the whole of the space in their sheath. It is on the medial
side of the vein, bounded medially by Gimbernat's ligament (which
is at the medial extremity of the inguinal ligament) and closed by
transversalis fascia only, which at this spot is called the crural
septum (septum crurale).

The femoral canal extends downward from this ring about
three-quarters of an inch in the sheath of the femoral vessels.

HERNIA

Hernia is denned as a tumor formed by the protrusion of con-
tents of a cavity through its wall. This may occur at any weak
place in the wall, but is most frequent in the region of the inguinal
or femoral canals.

If any structure slips accidentally through the inguinal canal it
forms. an inguinal hernia, which most commonly contains a loop
of bowel. To replace the bowel or other structure is to reduce the
hernia. If the loop cannot be replaced, the hernia is irreducible;
and should it become so distended as to interfere with the circula-
tion, it is strangulated.

In direct inguinal hernia the contents of the tumor have passed
directly through the conjoined tendon and subcutaneous ring. In
indirect inguinal hernia the contents of the tumor have passed
through the whole length of the inguinal canal — that is, first the
abdominal ring, then the canal, then the subcutaneous ring.

Umbilical hernia occurs at the umbilicus; ventral hernia at
any other part of the abdominal wall, except one or both rings.

Diaphragmatic hernia occurs at a weak or defective point in
the diaphragm where an abdominal structure may press its way
into the thorax.

In femoral hernia the bowel or other structure passes through
the femoral ring into the femoral canal and pushes its way through
the femoral sheath at the oval fossa, or saphenous opening.

Femoral hernia is more common in women — inguinal hernia
in men.

THE EXTREMITIES COMPARED

Both extremities are servants of the head and trunk. The
lower, being fashioned for bearing weight and also for walking or
running, are organs of locomotion, transporting the body from
place to place as necessity or convenience may dictate; while the

THE EXTREMITIES COMPARED

373

Ulnar nerve and artery
Radial nerve and
artery

upper are organs of prehension, since they can reach forth and
secure various things which are required for the use of the body.

Flexion of the arm is accomplished by a two-headed muscle —
the biceps; flexion of the thigh by a double muscle, the ilio-psoas.
Extension of the elbow is accomplished by a three-headed muscle,
the triceps; extension of the knee requires a powerful four-headed
muscle, the quadriceps.

. We have learned to apply the terms medial and lateral to the
body while in the ana-
tomical position, in which
the forearm is supinated;
therefore the thumb is said
to be on the lateral border
of the hand, but the leg
cannot be supinated, and
the great toe lies on the
medial border of the foot.

Observe that the toes
of civilized man are freely
flexed and extended, but
have no other independent
motions . They are slightly
affected by the action of
plantar muscles, but the
foot has lost the suppleness
it might have had without
wearing shoes. The fin-
gers, however, can all be
moved sideways; the me-
dian line of the hand is a line drawn to the tip of the middle finger,
and the digits are said to be abducted or adducted, according as
their motion is from or toward this line.

The freedom and mobility of the thumb add very greatly to the
usefulness of the hand in grasping, carrying, etc. If the fingertips
approach each other, the hand falls into a gently curved position
forming a cup, the "cup of Diogenes." If the hand be closed
forcibly with the thumb holding the fingers against the palm, it
becomes a solid irregular mass, the "fist," and so an ever-available
weapon of offense or defense.

Branches to hand

FIG. 240. — THE FOREARM, ANTERIOR.

374

Euprascapular nerve and artery

ANATOMY AND PHYSIOLOGY

The shoulder (and whole upper extremity) is pulled forward

by the action of the anterior
serratus on the shoulder blade,
and if this motion is accom-
panied by a sudden forcible
extension of the arm and fore-
arm, that is "striking out from
the shoulder."

REVIEW NOTES CONCERNING
THE EXTREMITIES

The upper extremity —
From the shoulder down, the
anterior surface is the flexor
surface, and the posterior is
the extensor surface of the
extremity.

Arm. Anterior. — The bi-
ceps muscle, with the median
nerve and brachial vessels on
its medial border. Posterior.
— Triceps muscle, with radial
nerve in the groove between
the two humeral heads.

Forearm. Anterior (Fig.
240). — Superficial flexor mus-
cles and the round pronator
from the internal epicondyle.
Deep flexor muscles from shafts
of the radius and ulna, and
median nerve between the su-
perficial and deep groups.
Posterior. — Extensor muscles
and the short supinator from
the external epicondyle. La-
teral or radial side, brachio-
radialis from the external
epicondylar ridge.

FIG. 241. — THE ARM AND FOREARM
POSTERIOR.

STRUCTURES IN THE PALM 375

The hand. Palm. — Observe the thenar eminence of thumb
muscles; the hypothenar eminence of little-finger muscles, and
between them the hollow of the hand, where the long flexor
tendons lie. The deep palmar arch is underneath the tendons;
the superficial arch lies upon them; the strong palmar fascia holds
the tendons in a compartment lined with synovial membrane.
Dorsum. — The extensor tendons are plainly seen. The radial
artery may be felt in the "anatomic snuff-box" (between two of the
extensors of the thumb as it winds around the first metacarpal bone
to reach the deep palm).

The long flexor and extensor tendons of the fingers may be
plainly felt and seen at the wrist.

The lower extremity. — The inguinal ligament stretches from
the spine of the ilium to the tubercle of the pubes.

The femoral artery, femoral vein, and femoral nerve pass under
the ligament, the artery lying on the psoas muscle. Their order
from the medial side outward is V-ein, A-rtery, N-erve.

From the hip down, the anterior surface is alter-
nately flexor and extensor

The posterior surface is exactly the reverse.

Flexor for hip.
Extensor for knee.
Flexor for ankle.
Extensor for toes.
Extensor for hip.
Flexor for knee.
Extensor for ankle.
Flexor for toes.

Thigh. — Anterior and sides of the femur are covered by the
quadriceps muscle, which extends the knee. The sartorius muscle
crosses from the anterior spine of the ilium to the middle of the
medial side of the thigh and down to the tibia, and when it con-
tracts it makes a depression rather than an elevation, because it
binds the soft tissue under it. Posterior. — The biceps, semi-
membranosus and semitendinosus muscles flex the knee; they are
hamstring muscles, making the upper boundaries of the popliteal
space. The medial side of the thigh is occupied by the adductor
muscles, with the obturator nerve and vessels.

Leg. Anterior. — The medial surface of the tibia is called sub-
cutaneous because it is not covered by muscles; the long saphenous
nerve and vein extend the whole length of this surface.

The anterior tibial muscles occupy the neighboring surfaces of

376

ANATOMY AND PHYSIOLOGY

Sciatic nerve

Anterior tibial
nerve

Popliteal artery
Tibial nerve

Peroneal nerve

Ant. tib. artery

Tibial nerve

Post. tib. artef

FIG, 242. — THE FEMORAL ARTERY. FIG. 243. — THE SCIATIC NERVE.

FEMORAL AND SCIATIC NERVES 377

the tibia and fibula, and their tendons all pass in front of the
ankle-joint to flex it (dorsal flexion). The lateral side of the leg is
occupied by the peroneus longus and brevis whose tendons pass
behind the lateral malleolus to extend the foot. They are ac-
companied by the superficial peroneal nerve which supplies them
(ant. tibial nerve).

The long tendons for the toes are plainly visible on the dorsum
or top of the foot, and also those of the short flexor, which has four
tendons belonging to the four medial toes.

Posterior. — The calf muscles, which lift the heel, completely
cover the deep muscles whose tendons pass into the sole of the foot
behind the medial malleolus to extend the foot.

The deep, or posterior tibial muscles, lie between tibia and fibula
bound down by the deep transverse fascia of the leg.

The large nerves for the lower extremity are the femoral and
the sciatic.

The femoral comes under the inguinal ligament into Scarpa's
triangle and immediately breaks up into branches which supply
the structures of the thigh, the long saphenous nerve being the
only branch to go below the knee. It runs all the way to the
medial border of the foot.

The sciatic comes through the great sciatic notch, descending
between the great trochanter and the tuber of the ischium into
the back of the thigh, to divide at the popliteal space into the
tibial and the common peroneal nerves. The tibial nerve continues
under the calf muscles and into the plantar region. The peroneal
nerve winds around the head of the tibia to the front of the
leg, sending the deep peroneal branch to the anterior muscles, and
dorsum of the foot.

LOCATION OF LARGE VESSELS AND NERVES IN THE
EXTREMITIES

The vessels and nerves are so placed as to be in the least
possible danger from pressure or blows. For example, the axillary
vessels and brachial plexus are deep in the axilla; the brachial
vessels and median and ulnar nerves are on the least exposed side
of the arm, and they pass in front of the elbow- joint where the
motion of the joint will not interfere with them. So in the fore-

378 ANATOMY AND PHYSIOLOGY

arm, the radial and ulnar arteries and nerves are protected by
muscles. At the wrist they also pass into the hand on the flexor
surface.

The large nerve which passes behind the humerus, the radial
nerve, is covered by the thick triceps muscle and winds to the front
of the bone to pass the elbow-joint on its way to the forearm.

The femoral vessels and nerves are in the fold or flexure of the
groin, and they wind around the femur to reach the flexor surface
of the knee. Both anterior and posterior tibial arteries are well
protected by muscles — the posterior tibial especially — which is
under the calf muscles and the transverse fascia of the leg. As it
passes the ankle-joint it lies under strong ligaments on the medial
side of the joint, where it would not be put on the stretch during
any natural movement of the foot nor exposed to blows. Again,
the large arteries of the hand are in the palm, while those of the
foot are in the sole.

POINTS FOR COMPRESSION OF LARGER ARTERIES

The temporal, on the zygoma.

The external maxillary, on the lower border of the mandible.

The subclavian on the first rib, behind the clavicle (downward
and backward).

The axillary, on the humerus, in the lower part of the axilla.

The brachial, on the humerus, under medial border of the biceps
muscle.

The radial and ulnar, on the bones of same name, in the lower
part.

The femoral, against the ramus of the pubic bone, just below
the inguinal ligament.

Note. — The subclavian artery is crossed by the scalenus
anticus muscle which divides it into first, second, and third por-
tions. The axillary artery is crossed by the pectoralis minor
muscle, which divides it into first, second, and third portions. The
common carotid artery is crossed by the omo-hyoid muscle; the
portion below the muscle is in the muscular triangle of the neck ;
the portion above is the carotid triangle.

CHAPTER XXVII
REFERENCE TABLES

379

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387

GLOSSARY

Abdomen. From a word meaning to conceal. The abdomen contains or conceals the

abdominal organs.
Abduction. From a Latin word meaning to lead from. The abdncens muscle leads, or

turns, the eye from the median line.
Acetabulum. A small vessel or cup for vinegar. The name given to the round

depression or cavity of the hip bone or os coxae, for the head of the femur.
Acid. Sour. Acids redden blue litmus paper.
Accommodation. The adjusting or focussing of the eye for vision at different

distances.

Acromegaly. A disease characterized by over-growth of the face and extremities.
Acromion. From Greek words meaning summit and shoulder. The process of bone

at the highest point of the shoulder.
Adduction. Leading toward.

Adenoid. Resembling a gland or aden. A gland-like growth in the naso-pharynx.
Adipose. Fatty. Fat.

Afferent Bearing toward. Afferent vessels enter organs.
Ala. A wing. (Plural, aid).
Alimentary. Pertaining to food or aliment, as, the alimentary tract, which contains

the food until it is digested.

Alkaline. Opposite of acid. An alkali turns red litmus paper blue.
Alveolus. The border of the jaw bone, named for the cavities which contain the

teeth. (Alveolus, a little hollow.)

Ameba. A one-celled, jelly-like living being, which constantly changes its form.
Ameboid movements. Movements which cause a change of form, like those of the

ameba.

Amphoteric. Like both. Applied to fluids which possess certain qualities resem-
bling both alkalies and acids.
Amyloid. Starchy or starch like.

Amylopsin. The starch-digesting ferment of pancreatic fluid.
Anastomosis. The opening of one vessel into another. Literally — to bring to a

mouth.

Ancon. The elbow. Anconeus, a muscle of the elbow-joint.
Annulus. A little ring. (A nnulus avails, the oval little ring of the heart.)
Anonyma. Without a name.

Antebrachium. The forearm. From ante, before, and brachium, the arm.
Antecubital. Applied to the space in front of the elbow. From ante, before, and

cubit, the forearm.

Antrum. A cave. The hollow in the maxilla is called the Antrum of Highmore.
Aorta, The largest artery in the body.
Apnea. Suspension of breathing.

Aponeurosis. A layer of strong white fibrous tissue (meaning form a tendon).
Aqueous. Watery, from aqua, water.
Arachnoid. Like a spider's web, for fineness. One of the membranes of the brain

and spinal cord.
Areolar. Having little spaces.
Arterio-sclerosis. Hardening of the arteries.
Artery. A vessel carrying blood away from the heart.
Arthrosis. A joint or articulation.
Arytenoid. Shaped like the mouth of a pitcher.
Assimilation. The taking up of nutriment by the body tissues, in such a manner

that it becomes a part of them.
Asphyxia. A condition in which the blood is deprived of oxygen.

3QO GLOSSARY

Atlas. A fabled giant who bore the globe upon his shoulders. The first cervical

vertebra, upon which the skull rests.
Atrium. A hall, a chamber of the heart where blood enters.
Atrophy. Wasting. From a Greek word signifying want of nourishment.
Auricular. Shaped like, or belonging to, an ear or auricle.
Axis. The second cervical vertebra. Named because of the pivot around which the

atlas revolves (like a wheel around an axis).
Axone. An axis. The essential part of a nerve fiber.

Azygos. Without a yoke. The name of certain vessels which are not in pairs.
Biceps. Having two heads, as the biceps femoris; biceps brachii.
Bicuspid. Having two points or cusps. A bicuspid tooth.
Bone corpuscle. A formative cell of bone tissue.
Brachialis. Belonging to the arm, or brachium.
Bronchus. An air tube. (Plural, bronchi.) The smallest air tubes are called

bronchioles.

Buccinator. From a word meaning trumpet. The blowing or trumpeting muscle.
Bursa. Literally, a purse. The bursce are small sacs containing fluid and found in

the fascia under skin, or muscles, or tendons.
Calcaneus. The heel bone. The tendo calcaneus, or tendo Achillis, is attached to

the calcaneus.
Calculus. A stone-like body formed in some fluid of the body. Renal calculus, in

the kidney; biliary c., in the gall-bladder, etc.
Callus. . A thickened portion of the skin. The material thrown out (provisional

callus) for the repair of fractured bone, to become the permanent callus when

the bone is completely ossified.

Cancellous. Resembling lattice work. A cancellous or spongy bone.
Canine. Resembling a dog. Canine teeth, like a dog's teeth.
Canthus. The angle at the meeting of upper and lower eyelid; plural canthi.
Capillary. Resembling a hair in size. (Capillus, a hair.)
Capitellum, or capitulum. A little head, an eminence on the lower extremity of the

humerus.

Capsule. A structure which encloses an organ or part. (The capsule of a joint.)
Carbo-hydrate. A substance composed of carbon and water; sugars and starches.
Cardiac. Belonging to the heart or cardia.
Caries. Decay of bone. Carious, decaying.
Carotid. The name of the large arteries of the neck, once thought to cause sleep.

From a Greek word meaning to produce sleep.
Caruncle. A small soft projecting tumor. Urethral caruncle, a minute tumor of the

urethral mucous membrane, made up mostly of nerves and vessels.
Casein. The proteid or cheesy part of milk.
Cast. An albuminous structure moulded in tubular form.
Cauda equina. A horse-tail. The name given to the bundle of spinal nerves in the

lower portion of the spinal canal.

Cecum. Blind. The blind pouch at beginning of the large intestine.
Celiac (cceliac). Pertaining to the celia or belly.
Center. In the nerve system, a center is a collection of gray cells. The central

nerve system comprises the brain and spinal cord, which contain the large nerve

centers. Central convolutions contain a majority of motor centers.
Centrifugal. Referring to a force which is exerted from the center outward; a

centrifugal nerve conducts impulses from a center.
Centripetal. Applied to a force which seeks a center; a centripetal nerve conducts

impulses to a center.
Cerebellum. Little brain.
Cerumen. The wax of the ear. (Cera, wax.)
Cervix. Neck. Cervical, belonging to or resembling a neck.
Choana. A funnel. The choana are the posterior openings from the nose into the

pharynx.

Choroid. Like the chorion, which is a fetal membrane bearing blood-vessels.
Cicatrix. A scar. It is formed of fibrous connective tissue.

Cilia. Eyelashes. Ciliated, having tiny hair-like projections, as ciliated epithelium.
Ciliary. ^ The ciliary region of the eye presents radiating lines, caused by folds of the

tissues composing it (ciliary 'processes).

GLOSSARY 391

Circumduction. Leading around. This is the motion made when a part, is moved

around in a circle, one end being stationary. The extremities, the digits and

the head, may be circumducted.

Circumflex. To bend around. Circumflex arteries wind around the arm or thigh.
Circumvallate. Walled around. The circumvallate papillae at the base of the

tongue are encircled by a ridge.

Clavicle. The clavicula, which resembles a very ancient key.
Climacteric. Literally, the round of a ladder. Any time of life when the system is

believed to undergo marked and permanent changes; usually applied to the

time of the cessation of menstruation.
Coagulation. From coagulare, to curdle. The clotting of blood. Coagulum, a

blood clot.
Coccyx. A cuckoo's beak. The bone at the end of the spinal column, named from

its shape.
Cochlea. A conch-shell. A cavity of the internal ear resembling a snail-shell in

form.
Collateral. From words meaning side and together. Collateral circulation is secured

by the union of branches of two vessels, whereby the main current of fluid may

be carried by this side route if necessary.
Colliquative. Literally — a melting together. Colliquative stools are profuse and

watery.
Commissure. A placing together. A commissure connects two parts of an organ,

as the commissures of the brain.
Communis. Common. Applied to a muscle whose tendons are common to several

organs.

Concha. A shell.

Condyle. A knuckle. A rounded eminence of bone.

Conjunctiva. Connecting. The mucous membrane which connects the under sur-
faces of the eyelids.
Conoid. Shaped like a cone.
Convoluted. Twisted.
Co-ordinate. From words meaning together, and to order or regulate. Co-ordination

is the systematic acting together of several parts.
Coracoid. Like a crow's beak. The coracoid process of the scapula.
Corium. Leather. The deep portion of the skin from which leather is made.
Cornea. Horny. The tough transparent -membrane in the anterior of the eyeball.
Cornua. Plural of cornu, a horn.

Coronal or coronoid. Pertaining to, or resembling a crown.
Coronary. The coronary arteries encircle the base of the heart.
Corpus callosum. The transverse commissure of the cerebral hemispheres.
Corpuscle. A little body. A blood cell. Malpighian corpuscle, a structure in the

kidney. Lymph corpuscle, a cell formed in a lymph gland.
Corpus luteum. Yellow body. The substance formed in a ruptured Graafian

follicle of the ovary.

Cortex. Bark. The superficial layer, as the cortex of the brain.
Costal. Relating to a rib or costa.

Coxae. Plural of coxa, the hip; also the genitive form, as os coxa, the bone of the hip.
Cranium. The part of the skull which contains the brain.
Crest. A ridge of bone, either on a surface or at the border.
Cretinism. The condition of a cretin or undeveloped person, both mentally and

physically.

Cribriform. Resembling a sieve.

Cricoid. Like a ring. The cricoid cartilage of the larynx is shaped like a seal ring.
Crucial. Like a cross. The crucial iigaments cross each other.
Crural. .Belonging to or like the lower extremity, from crus, a leg; as the crural

nerve, the crura (or legs) of the diaphragm.
Cystic. Relating to a cyst, or a sac containing fluid (cystic duct). A cystic ovary has

cysts developed from its substance.
Deglutition. The act of swallowing.
Deltoid. Shaped like the Greek letter delta, A.
Dental. From dens, a tooth, belonging to a tooth.
Dentated. Having points which resemble teeth.
Dentition. The eruption or "cutting" of the teeth.

392 GLOSSARY

Diapedesis. A jumping through. The passing of blood cells through the walls of

capillaries.

Diaphoretic. A remedy which increases the amount of perspiration.
Diaphragm. A wall across a space. The muscle which separates the cavity of the

thorax from that of the abdomen.
Diaphysis. The greater part of the shaft of a bone.
Diarthrosis. A movable joint.
Diastole. A Greek word meaning a drawing apart. The dilation of the chambers of

the'heart.

Digastric. Double bellied as the digastric muscle.
Digit A finger or toe.
Distal. Farthest from the head or trunk.
Diuretic. A remedy which increases the quantity of urine.
Dorsal. Belonging to the dorsum, or back.

Duodenum. Meaning twelve. The duodenum is twelve finger-widths long.
Dura mater. Hard mother. The fibrous outer membrane of the brain and spinal

cord.

Dyspnea. Difficult breathing.

Edema. Swelling caused by effusion of serous fluid into areolar tissues.
Efferent Bearing from. Efferent vessels leave organs.

Effusion. An abnormal pouring out (or secreting) and collection of fluid in the body.
Element A substance which cannot be divided into simpler substances.
Eliminate. From words meaning without the threshold. To excrete substances

which are useless.
Embryo. The ovum and structures belonging to it constitute the embryo, until the

fourth month of intrauterine life.
Endo-. Within. Endocardium, within the heart. Endothelium, the epithelium of

the interior of circulatory organs.
Endomysium. The sheath of a muscle-fiber.
Endosteum. The lining of medullary canals in long bones.
Ensiform. Sword-shaped. The appendix of the sternum.
Enteric. Pertaining to the enter on or intestine, as enteric or typhoid fever.
Enzyme. Any ferment in a digestive fluid.
Epi. Upon, as epi-condyle, epidermis, epiglottis.
Epimysium. The connective-tissue muscle sheath.
Epiphysis. A part of a bone which is formed independently, and joined later to

complete the whole bone.
Epithelial. Pertaining to epithelium.

Epithelium. The uppermost or superficial layer of cells of a body surface.
Erythrocyte. A red cell of the blood. A red corpuscle.
Esophagus. From a Greek word meaning to carry food. The esophagus transmits

food from pharynx to stomach.

Ethmoid. Sieve-like. The ethmoid bone has many openings on its surface.
Eversion. Turning outward. To evert an eyelid is to fold it back so as to expose the

interior surface.

Excretion. A waste substance to be removed from the body. The process of re-
moving waste from the tissues.

Extension. Stretching out or extending. (Bending backward is over-extension.)
Exudate. A collection of material which has filtered through the walls of vessels into

surrounding tissues.
Falciform. Sickle-shaped.
Falx. A sickle.
Fascia. A band; plural, fascia. The tissue which binds organs or parts of organs

together.
Fauces. From the Latin word/a«#, the throat. Isthmus of, the space bounded by

the soft-palate, tonsils and tongue. Pillars of, the folds connecting the soft

palate with the tongue and pharynx. (The tonsil is between the pillars of

either side.)

Femoral. Belonging to the femur or thigh bone.
Fetus. After the fourth month, the embryo becomes the fetus.
Fibrin. A proteid substance of the blood which causes coagulation.
Filiform. Thread-like in shape, slender; as filiform papillae of the tongue.
Fimbria. A fringe; fimbriated, having a fringe-like appearance.

GLOSSARY 393

Fissure. A cleft or groove, as a fissure of the brain surface.

Fistula. A pipe. A tube-like passage caused by disease.

Flava. Plural of flavus, yellow. Applied to elastic ligaments which contain yellow

elastic tissue.

Flexion. Bending. Flexure, a bend.
Follicle. A very small sac (or bag) containing a secretion.
Fontanelle. A little spring. A membranous spot in the infant's skull; the name

suggested by the rising and falling caused by the child's respirations.
Foramen. A hole. Plural, foramina.
Fossa. A depression or concavity.
Fourchette. A little fork.
Fovea. A small pit. The fovea cenlralis is a tiny depression in the macula lutea of

the retina.
Frenum. A curb or bridle. The frenum lingua is the fold of mucous membrane

attaching the tongue to the floor of the mouth.
Fundus. The base.

Fungiform. Shaped like a fungus or mushroom.
Fusiform. Spindle-shaped.

Ganglion. A knot. (Plural, ganglia.) A collection of nerve cells.
Gaster. The stomach. Gastric, belonging to the stomach or gaster.
Gastrocnemius. The belly of the leg. The prominent muscle of the calf of the leg.
Genioglossus. Belonging to the chin and tongue.
Genu. A knee.

Glabella. A little smooth space. The smooth space between the eyebrows.
Gladiolus. A little sword. The body of the sternum.
Gland. A collection of cells which can form a secretion or an excretion.
Glans. The head of the clitoris or penis.

Glenoid. Having the form of a shallow cavity. Belonging to a cavity.
Glossopharyngeal. Belonging to the tongue and pharynx.
Glottis. The upper opening of the larynx. Epiglottis, ,the leaf-shaped cartilage

upon the upper border of the larynx.
Glucose. Grape sugar. Dextrose.
Gluteus. Belonging to the gluteus or buttock.
Glycogen. A white substance formed principally in the liver. Sometimes called

animal starch.

Gustatory. Associated with the sense of taste.
Gyre. From gyrus, a circle. A convolution (referring to the convolutions of the

brain).

Haversian. Name applied to the tiny canals in bone tissue, from the English anato-
mist Havers.

Hepatic. Belonging to the liver or hepar.
Hemoglobin. The oxygen-carrying substance of red blood cells, to which their color

is due.

Hemolysis. Destruction of red blood cells.
Hemorrhoidal. From a word meaning flowing with blood. Pertaining to a hemor-

rhoid or pile.
Hilum. Literally, a little thing. Applied to the depression where vessels enter and

leave an organ.

Hormones. Chemical substances (character unknown), formed (probably) in duct-
less glands, and conveyed by the blood to other organs, to influence their
activity.

Hyaline. Resembling glass. Hyaloid has a similar meaning.
Hydration. Saturating with water.
Hydrocephalus. A collection of fluid either within the ventricles or outside of the

brain.

Hyoid. U-shaped, as the hyoid bone.
Hypertrophy. Over-growth. Derived from two Greek words meaning too much

nourishment.
Hypochondrium. Under the cartilage. The hypochondriac region is under the

cartilages of ribs. (Hypo- under.)

Hypodermoclysis. Injection of fluid under the skin — in quantity.
Hypogastric. Under the stomach.
Hypoglossal. Under the tongue.

394

GLOSSARY

Hypothenar. Under the palm or sole. The eminence on the medial side of the

palm or the sole.
Ileum. A roll or twist; the portion of small intestine which appears rolled or

convoluted.

Ilium. The upper portion of the hip-bone or os coxat.
Incisor. A cutting instrument. The front teeth are incisors.
Index. Indicator. The first finger named from its common use.
Induration. Hardening of the tissues.
Infra. Beneath. ,

Infundibulum. A funnel-shaped space or part.
Inhibition. The restraining or stopping of normal action.
Inguinal. Belonging to or near to the thigh or inguen.
Inlet The superior opening or brim or strait of the pelvis.
Innominatum. Unnamed.
Inorganic. A term applied to certain substances, mostly mineral, found in all organs

but not produced by them.
Instep. The bend of the foot, dorsal aspect.

Inter. Between, as intercostal, between ribs; intercellular, between cells, etc.
Inversion. A turning in, as inversion of the eyelashes; inversion of the foot.
Invertin. The ferment of intestinal juice.
Involution. The changing back to a former condition, of an organ which has fulfilled

a function, as the involution of the uterus after parturition.
Iris. A circle or halo of colors. The colored circle behind the cornea of the eye.
Ischium. The lowest part of the hip-bone or os coxa.

Jejunum. Empty. The third portion of the small intestine, usually found empty.
Jugular. Belonging to the neck orjugulum.
Kidney or ren (plural, renes). An important organ of elimination or excretion, in

which the urine is formed.
Labium. A lip. (Plural, labia).

Lacrimal. Having to do with tears or lacrymce, as the lacrimal gland.
Lacteal. Like milk (from lac, milk). The lacteals are lymph- vessels which carry the

milky-looking chyle.
Lactose. Milk sugar.

Lambdoid. Resembling the Greek letter lambda, \.
Lamella. A little plate, or thin layer.
Lamina. A plate or layer.
Larynx. The part of the air-passage extending from the base of the tongue to the

trachea.

Latissimus. Broadest. Latissimus dor si, broadest of the back.
Lens. A glass or crystal curved and shaped to change the direction of (or refract)

rays of light.

Lentiform. Shaped like a lens.
Leptomeningitis. Inflammation of the thin membranes of the brain — the arachnoid

and pia mater.

Lesion. The effect of an injury, or of disease, in a tissue.
Leucocyte. A white cell of the blood or lymph. Leucocytosis, an increase in the

number of leucocytes.

Levator. A lifter. Levator palpebrce, lifter of the eyelid.
Linea. A line.
Linea alba. A white line.
Linea aspera. A rough line.
Lingual. Belonging to the tongue or lingua.
Lobule. A little lobe.
Lumbar. Belonging to the loin or lumbus.
Macula. A spot. Macula lutea, yellow spot.
Major. Greater or larger.
Malar. Belonging to the cheek or mala.
Malleolus. A little hammer. The two malleoli are the lower extremities of tibia

and fibula.

Mammary. Pertaining to the breast or mamma.
Mandible. Derived from mandere, to chew. The lower jaw-bone.
Manubrium. A handle. The first part of the sternum.
Masseter. A chewer. One of the muscles of mastication or chewing.

GLOSSARY 395

Mastitis. Inflammation of the breast.

Mastoid. Shaped like a breast.

Maxilla. The jaw-bone. Applied to the upper jaw-bone.

Meatus. A passage.

Medial. Toward the middle line.

Median. Middle, as the median line of the body.

Mediastinum. From Latin words meaning to stand in the midst. The space in the

middle of the thorax.
Medulla. Marrow.

Medullary. Pertaining to, or like, marrow. The medullary canals contain marrow.
Meninges. Membranes. Membranes of the brain and spinal cord.
Mental. From the Latin word mens, the mind.
Mental. From the Latin word mentum, the chin.
Mesentery. From two Greek words, meaning middle and bowel. (The mesentery

connects the bowel with the posterior abdominal wall.)
Metastasis. From a Greek word meaning to transpose.
Minimus. Least or smallest. Minimi digiti, of the smallest digit.
Minor. Lesser.

Mitral. Resembling a miter in outline.

Molar. Like a mill-stone or mola. The molar teeth grind the food.
Mucous. Containing or resembling mucus.

Mucus. A thick clear fluid secreted by the cells of mucous membranes.
Naris. The nostril. (Plural, nares.)
Navicular. Boat-shaped, as the navicular bone.

Necrosis. The death of a portion of tissue, while still surrounded by living structures.
NeuraL Pertaining to nerves. The neural axis is the spinal cord. The neural

canal is the spinal canal. The neural cavity contains the brain and spinal cord.
Neuron. A single nerve cell with its branches.
Nucha. The nape of the neck.

Nucleolus. A smaller nucleus within the nucleus of a cell.
Nucleus. A small round body near the center of a cell. The most important part

of a nucleated cell.
Neuron. A unit of the nerve tissues. It consists of cell body or center, axon and

terminal divisions.
Nutrient. Nourishing.

Nutrition. The process of nourishing the cells of living tissues.
Olecranon. The large process at the upper end of the ulna. The head of the elbow.
Occipital. Belonging to the back of the head, or the occiput.
Odontoid. Resembling a tooth in shape.

Omentum. A fold of peritoneum connected with the stomach.
Omos. The shoulder. Omo-hyoid, belonging to shoulder and hyoid bone, as the

omo-hyoid muscle.

Ophthalmic. Belonging to the eye or ophthalmos.
Ora serrata. The serrated or toothed margin of the retina.
Orbicular. Ring-shaped. A ligament -which resembles a little circle.
Organ. A structure designed for a particular function or use. Organic substances

are formed in, or by, organs.

Os. A bone. (Plural, ossa.) Ossicle, a little bone.
Os. A mouth. (Plural, ora.)
Osseous. Bony.

Ossification. The formation of bone.
Osteology. The science which treats of bones.

Ostium venosum. A venous door. The door or opening from an atrium to a ven-
tricle in the heart, for the passage of venous blood.
Outlet The inferior opening or strait, of the pelvis.
Ovum. An egg. (Plural, ova.)

Palpebra. An eyelid. Palpebral fissure, the Assure between the eyelids.
Pancreas. From words meaning all and flesh. Pancreatic fluid digests all foods.
Papilla. A Latin word meaning a nipple. A soft conic eminence.
Parietal. Resembling a wall (paries).

Parotid. Near the ear. The parotid gland is around the external ear.
Parturition. The act of bringing forth, or giving birth to, young.
Patella. A little pan. The sesamoid bone in front of the knee-joint; the "knee

pan."

396 GLOSSARY

Pectoral. Connected with the breast, as pectoral muscles.
Pedicle. A little foot. Peduncle has a similar meaning.
Pelvis. A basin. The cavity in the lowest part of the trunk.
Pericardium. Around the heart.
Perichondrium. Around cartilage. ,

Perimysium. The connective tissue around small bundles of muscle fibers.
Perineal. Pertaining to the perineum, that region of the body in front of the anus.
Periosteum. Around bone.

Peristalsis. From two Greek words, meaning around and constriction. The intes-
tinal movements which propel the food.
Peritoneum. From two Greek words, meaning around and to stretch. The serous

membrane around abdominal organs.
Peroneal. Relating to the fibula or perone. Peroneal nerves supply muscles on the

fibula.

Petrous. Hard, like a rock.
Phagocyte. White blood-cells having the power to take micro-organisms into their

substance and to digest them.
Phalanges. Plural of phalanx, a body of troops drawn up closely together. The

fingers and toes.
Pharynx. That part of the food passage which connects the mouth and esophagus.

The upper part is the naso-pharynx, an air passage.

Phlebotomy. Cutting a vein. The operation of bleeding or venesection.
Phrenic, Pertaining to the phren or diaphragm, as, the phrenic nerves.
Pia mater. Tender mother. The delicate membrane which bears the blood-vessels

of brain and cord.
Pigment. Coloring matter.

Plantar. Belonging to the sole of the foot or planta.
Plasma. Something moulded. The name given to the fluid portion of the blood,

from which tissues are formed. Lymph plasma, the fluid portion of lymph.

Muscle plasma, the fluid portion of the contents of a muscle cell.
Platysma. Broad. Platysma muscle.
Pleura. A side. The name of the serous membrane which lines the thorax and

covers the lungs.
Plexus. A network. An arrangement of vessels and nerves which appear to be

woven together.

Pneumogastric. Belonging to the lungs and stomach.
Pollicis. Genitive form of pollex, the thumb.
Polymorphonuclear. Having nuclei of various shapes.
Poples. The ham; a space behind the knee (popliteal space).
Popliteal. Belonging to the poples or back of the knee.
Porta. A gate. The portal vein enters the porta or gate of the liver.
Prehension. Taking hold of.

Pre-molar. Applied to the teeth which stand immediately in front of the molars.
Process. In anatomy, a projection.
Pronation. Literally, bending forward. The position of the hand when the thumb

is toward the body. The act of turning the hand face downward, or in the

prone position.
Prostate. From Greek words meaning to stand before. The prostate gland is in

front of the neck of the bladder.

Protoplasm. A simple gelatinous cell substance. Bioplasm.
Protuberance. A knob-like projection.
Proximal. Near the head or trunk.
Psychic. Pertaining to the mind.
Pterygoid. Wing-shaped.
Pubes. The anterior portion of the os coxae.
Pulmonary. Pertaining to the lung or pulmo.
Quadriceps. Four headed.
Rachitis. From two words meaning spinal column and inflammation. A disease in

which the bones are deficient in lime salts.
Radius. A rod or spoke. The lateral bone of the forearm.
Ramus. A branch, as the ramus of the mandible.
Raphe. A seam. The union of two parts in a line, like a seam.

GLOSSARY 397

Reaction. Response to a stimulus or test. The iris reacts to the stimulus of light.

Urine reacts to the litmus test.

Reflex action. The simplest form- of nerve response.

Receptaculum chyli. Receptacle of the chyle, the beginning of the thoracic duct.
Recession. Withdrawal, as the margin of the gums from the teeth.
Rectus. Straight, as rectus muscles. Rectum has the same meaning.
Recurrent. Running back. Recurrent arteries turn back.
Renal. Pertaining to the ren or kidney.
Retina. A net. The complicated nerve coat of the eye.

Rigor mortis. Rigidity of death. The muscular stiffness which occurs after death.
Rugae. Folds. (Plural of ruga.) Wrinkles.
Saccharose. Cane sugar.
Sacral. Relating to the sacrum, or bone which protects the pelvic organs which

were held sacred by the ancients.

Sagittal. Like an arrow — straight. The straight suture of the skull.
Saline. Salty.

Saliva. The mixed secretions of glands of the mouth and salivary glands.
Saphenous. Manifest or plainly seen. The large superficial vein on the medial

side of the lower extremity and the longest vein in the body.
Sartorius. From the Latin sartor, tailor. The "tailor muscle."
Sciatic. Ischiatic. Pertaining to the ischium.

Sclerotic. Hard. The sclerotic is the tough fibrous coat of the eye; the solera.
Scrobiculus cordis. Literally, pit of the heart. The little depression at the end of

the sternum. The "pit of the stomach."

Sebaceous. Applied to the glands which produce the oil or sebum of the skin.
Secretion. A substance either nourishing or useful, formed by glandular cells.
Septum. A partition. (Plural, septa.)

Serous. Of the nature of serum, a thin watery fluid derived from the blood.
Serrated. Haying teeth like the border of a saw. (The border of the terrains ant.

muscle is thus.)

Serum. A watery fluid separated from blood.

Sesamoid. Resembling a grain in form. Applied to small nodules of bone some-
times found in tendons.
Shaft. The main portion of a long bone.
Sigmoid. Curved like the letter S. As the sigmoid (or transverse) sinus; the

sigmoid colon.
Sinus. A curve, or a hollow. A bone sinus contains air. An abnormal passage

opening on the surface of the body is sometimes called a sinus.
Soluble. That which can be dissolved or made into a solution.
Specific gravity. The weight of a substance, judged in comparison with an accepted

standard. In the case of urine, the standard is an equal volume of distilled

water — at greatest density.
Sphenoid. Wedge-shaped.
Sphincter. A muscle which closes an orifice.
Splanchnic. Pertaining to the viscera or internal organs.
Squamous. Shaped like a scale.
Steapsin. The pancreatic ferment which digests fats.
Stereognosis. The faculty of recognition of objects by handling them.
Sternum. Breast bone.

Stimulus. That which excites activity or function.
Striated. Striped.

Styloid. Pointed, like the stylus, which was used in ancient times for writing.
Sub. Under.

Subcutaneous. Under the skin.
Submucous. Under mucous membrane.
Subserous. Under serous membrane.
Sudoriferous. Bearing sweat, as sudoriferous glands. (Sudoriparous has the same

meaning.)
Super. Above.

Superciliary. Above the eyelashes.

Supercilium. The eyebrow, or prominence above the eyelashes.
Supination. The attitude of one lying on the back. The position of the hand when

the little finger is next to the body, or when lying upon the back.

398 GLOSSARY

Supra. Above.

Sural. Belonging to the calf or sura, as the sural muscles.

Surgical neck. The constriction below the head of a long bone at the narrowest
portion of the shaft. The anatomic neck is the constriction (however slight)
immediately next to the head, between it and the shaft. The surgical neck
of the humerus and the anatomic neck of the femur are best examples.

Suture. A seam. (Latin, sutura.) The joints of the cranium are sutures.

Symphysis. A growing together, as the symphysis of the mandible.

Synarthrosis. An immovable joint.

Synovia. A fluid resembling the white of an egg, found in joint cavities and vaginal
synovial membranes.

Systole. A Greek word meaning contraction. The contraction of the chambers of
the heart.

Talus. The ankle bone upon which the tibia rests.

Tendo Achillis. The tendon of Achilles. The tendon of calf muscles attached to
the calcaneus or heel bone by which Achilles was held when his mother sub-
merged him in the river Styx, to render him invulnerable. Only the heel
remained un-wetted.

Tentorium. A tent. The tentorium cerebelli (of the cerebellum) covers the cere-
bellum.

Teres. Round. (Ligamentum teres — round ligament.)

Testes, or Testicles. The glandular bodies which secrete semen.

Thalamus. A Greek word meaning a bed. The optic thalamus is in the base or
bed of the brain.

Thenar. Relating to the palm or sole. Hypothenar — under the palm or sole —
applied to the eminences on the side corresponding to the little finger or toe.

Thorax. The chest. The portion of the trunk which contains the heart and lungs.

Thyroid or thyreoid. Shield shaped.

Torticollis. Twisted neck, wry neck.

Trabeculae. Little beams. (Plural of trabecula.) The cross bands of connective
tissue which support soft structures — as in the spleen.

Transudation. The passing of fluid through a membrane, as of the blood serum
through the walls of vessels.

Trapezium. A four-sided symmetrical figure. Trapezoid, resembling a trapezium,
but not symmetrical. Trapezius, applied to a muscle of the back.

Triceps. Three headed.

Trigone. A space or surface haying three angles or corners.

Trochanter. From a word signifying a wheel. (The muscles which are attached
to the trochanters roll the femurs.)

Trochlea. A pulley. A trochlear surface is a grooved convexity, as the trochlea of
the humerus.

Trypsin. The ferment of the pancreas which digests proteids.

Tuber. A swelling or bump.

Tubercle. A small projection like a swelling.

Tuberosity. A large projection on a bone.

Tumor. A welling of soft tissues.

Turbinated. Rolled, like a scroll.

Tympany. The condition caused by inflation of intestines with gas, so that they
sound hollow upon percussion, like a tympanum or drum.

Ulna. A cuoit; the elbow. The longer bone in the medial side of the forearm.

Umbilicus. From a Latin word, umbo, the name of the elevated or depressed point
in the middle of an oval shield.

UnguaL Belonging to the nail or unguis.

Urea. A substance representing the chief nitrogenous product of tissue waste.

Ureter. The duct of the kidney, which conveys urine to the bladder.

Urethra. The passage through which urine is expelled from the bladder.

Uvula. From uva, a grape, or cluster of grapes (which hangs down from the branch
where it grows).

VaginaL Like a sheath.

Vagus. From vagare, to wander.

Vallate. Situated in a cavity which is surrounded by a ridge.

Valvulae conniventes. Little valve-like folds. Seen on the mucous coat of the small
intestine.

GLOSSARY 399

Vascular. Having many blood-vessels.

Vaso-motor. Literally, vessel-mover. Applied to the nerves which dilate blood-
vessels or contract them, or vaso-dilators and vaso-constrictors.

Velum. Veil. Velum palati, the veil, or soft hanging portion of the palate or roof
of the mouth.

Vena cava. A large hollow vein.

Venesection. Cutting a vein. " Bleeding " or phlebotomy.

Ventral. Toward the front of the body, as the ventral cavity.

Ventricle. Literally, a little belly. From the Latin venter. A cavity in the brain
or in the heart.

Vermiform. Worm-shaped.

Vertebra. From a Latin word meaning to turn. Certain movements of the verte-
brae turn the body from side to side.

Vertex. The crown of the head.

Vestibule. A cavity of the internal ear through which stimulating impuses are
transmitted to auditory and vestibular nerves.

Villus. A hair (pi. villi). The villi of the intestine are hair-like in shape and belong
to the mucous coat.

Viscus. An internal organ of the head or trunk. (Plural, viscera.}

Vitreous. Glassy. The vitreous humor resembles glass in appearance. The
vitreous layers of the skull are brittle like glass.

Volar. Belonging to the palm or vola.

Xyphoid. Sword-shaped. The third piece of the sternum is the xyphoid or ensiform
appendix.

Zygoma. A yoke. The arch of bone at the side of the face formed by zygomatic
processes of frontal and maxillary bones.

INDEX

'Abdomen, abdominal organs, 365, 367

regions of, 366

Abdominal brain (Solar Plexus), 318
Abdominal wall, 94
Absorption, 166, 169
Accommodation, 338
Acetabulum, 48
Acromegaly, 267
Adipose tissue, 4, 5
Adrenal bodies, 264
Air or atmosphere, 23 1

air cells, 236

tidal volume, 239
Alimentary canal, 130
Ameboid movements, 173
Anatomic position and use of terms, i
Animal heat, 274
Antrum of Highmore, 25
Aorta, 187, 189
Apnea, 242
Aponeurosis, description of, 84

vertebral, 86
Apophysis, 15

Appendix ceci (vermiformis), 144
Aqueduct of Sylvius (of cerebrum),

303

Aqueous humor, 338
Arachnoid of brain, 305

of cord, 281

Arbor vitae, 302 (illus. 301)
Arches of foot, 73

of hand, 192, 193

of vertebrae, 39

palatine, 133

superciliary, 21

supraorbital, 20

zygoma tic, 33
Areolar tissue, 5
Arm, bone of, 56

muscles of, 104

Arterioles and arteries, 174, 175
Arterio-sclerosis, 216

26 401

Articular surface, 13
Articulations or joints, 1 7

of cranium, 24

of face, 28

of lower extremity, 70

of pelvis, 49, 50

of spinal column, 42

of thorax, 47

of upper extremity, 60
Ascites, 7
Asphyxia, 241
Assimilation, 166
Associated movements, 344
Atlas, 40

Auditory tube (Eustachian), 330
Auricle of heart, 176
Axillary space, 368
Axis (artery), 191

(bone), 40
Axon, 278

Bifurcation of aorta, 198
Bile, 150
Bioplasm, 4
Bladder, urinary, 246
Blood, 171

circulatory organs of, 174

coagulation of, 217

pressure, 216
Bone, articular, 13

markings, 13

nutrition, 15

repair of, 77

tissue, ii
Bones, completion of, 76

in infancy, 75

shapes of, 14

structure of, n
Brain, 299

fissures of, 300
Brain hemispheres, 300

lobes of, 300

4O2

INDEX

Breast (mammary gland), 260

muscles of, 103
Bronchi, 234
Bronchial muscle, 235
Bursa (plural, bur see), 71, 82

prepatellar, 72

Callus, 78

Canal, adductor, 371

anal, 146

auditory, 329

carotid, 23

central (of cord), 303

femoral, 371

Haversian, 12

Hunter's (or adductor), 371

inguinal, 371

internal auditory, 23

medullary, 14

nasal (or lacrimal), 34

neural, 53

nutrient, 15

semicircular, 331, 332

spinal (neural or dorsal), 43, 53
Cancellous or spongy tissue, 12
Capillaries, 175
Capitulum (capitellum), 56
Capsule, Bowman's, 246

internal, of brain, 301

of joints, 1 8

of lens, 337

of Tenon, 335
Carbohydrates, 153
Cardiac impulse, 177
Carpus, 58

meta, 59
Cartilage, 5

articular, 17

costal, 44

fibro-, semilunar, 70
sterno-clavic., 60
triangular, 62
Cartilages of larynx, 233
Cauda equina, 284
Cavities of body, 53

dorsal or neural, 53

ventral or visceral, 53
Cecum, 144
Cell body (nerve), 277
Cell, description, 4

Centers, brain (illus.), 311, 314

nerve, 279

of ossification, 15
Central fissure, 301
Cerebellum, 302
Cerebral localization, 311
Cerebro-spinal fluid, 280

system, 279

Cerebrum, 300, 322, 324
Cervical nerves, 286
Cervix uteri, 347
Chambers of eye, 338
Cheyne-Stokes breathing, 242
Choroid coat of eye, 336
Chyle, 161, 168, 222
Chyme, 160
Cilia, of air passages, 233, 235

of eyelids, 343
Ciliary muscle, 338
Circular folds (intestine) 142
Circulation (def.), 166

collateral, 195, 200, 380-385

fetal, 209, 211, 356

portal, 208, 209

pulmonary, 185, 187

systemic, 185, 187, 188
Circumcision, 354
Clitoris, 351

Coagulation of blood, 217
Coccyx, 42
Cochlea, 331, 333
Colon, 145
Colostrum, 262
Compact bone tissue, 12
Compression of arteries, 378
Condyle (def.), 13
Condyles, occipital, 21

of femur, 66

of mandible, 27

of tibia, 66
Conjoined tendon, 96
Conjunctiva, 336-341
Connective tissue, 5
Coordination, 297, 322
Corium of skin (cutis vera),

253

Cornea, 335

Corpus callosum, 300, 301 (Illust.)
Corpuscle of blood, 171, 172, 173
of kidney (Malpighian), 245

INDEX

403

Corpuscle of skin (touch), 254, 327

of spleen, 263
Corpus luteum, 340-350
Cortex of adrenal body, 264

of brain, 299

of kidney, 245
Cranium, 20, 29
Crest (def.), 13

of ilium, 48
Crura of cerebrum, 303

of diaphragm, 98
Crystalline lens, 337
Cutis vera (skin), 253

Dartos, 353

Decidual membrane, 355

Defecation, 165

Deglutition, 158

Dendrite, 277

Dentition (eruption of teeth), 36

Diameters of pelvis, 52

Diapedesis, 173

Diaphragm, 97, 121

of pelvis, no
Diaphysis, 15
Diastole of heart, 180
Digestion, 156
Digestive fluids, 131
Duct, common bile, 150

cystic, 150

hepatic, 149, 150

pancreatic, 148

right lymphatic, 223, 228

Stenson's, 134

thoracic, 223, 228

Wharton's, 134
Ductus arteriosus, 210

communis choledochus (or common
bile duct), 150

deferens (vas def.), 3 54
Duodenum, 141, 142
Dura mater, brain, 305

cord, 281
Dyspnea, 242

Ear, 329
Edema, 229
Elastic tissue, 5
Elimination, organs of, 244

Endocardium, 178
Endosteum, 14
Endothelium, 7
Enzymes (def.), 131, 165
Epicardium, 183
Epicondyle of femur, 66

of humerus, 56
Epidermis, 254
Epiglottis, 233
Epiphysis, 15
Epithelium, 6, 7

ciliated, 6, 233

respiratory, 230, 233
Erythrocyte (red cell), 171
Esophagus, 135, 136
Eustachian tube (auditory), 330
Excretion, 270
Expiration, act of, 238
External genital organs, 351
Extremities compared, 372
Eye, 335
Eyebrows, 341
Eyelids, 341

Face, bones of, 24

muscles of, 89, 90, 91

vessels and nerves, 360
Fallopian or uterine tubes, 348
Falx cerebri, 305
Fascia of body, deep, 80

iliac, in

lata, 8 i

lumbar, 82

palmar, 109

pelvic, in

plantar, 118

superficial, 82

temporal, 90

transversalis, 100, in

transverse of leg, 377
Fatigue poisons, 126
Fats, 153, 154
Feces, 164
Fibrin, 218
Fibrous tissue, 5
Fissure of Rolando (central), 300

of Sylvius, 301

transverse of liver (porta), 148
Floor of mouth, 131

404

INDEX

Floor of pelvis, no

of thorax, 98
Fontanelles, 32
Food, absorption of, 166

values, 272
Foods, 153

carbohydrates, fats, proteids, 153,

IS4, i5S
Foot, eversion of, 119

inversion of, 119
Foramen, infraorbital, 31

intervertebral, 44

jugular, 3 1

magnum, 21

mental, 31

Munro, 303

obturator or thyroid, 49

optic, 34

ovaJe, 210

sciatic, 50

supraorbital, 21

transverse, 40

vertebral, 39
Forearm, bones of, 57

muscles of, 105
Foreskin (prepuce), 354
Fossa (def.), 13

glenoid, 55

intercondyloid, 66

ischio-rectal, 368

lacrimal, 21

mandibular, 22

navicularis, 351

ovale (heart), 177
(thigh), 82

subscapular, 55
Fossa: of skull, 32
Frenum linguaj (bridle of tongue), 132

Gall bladder, 150
Ganglia, basal, 301

semilunar, 318

sympathetic (autonomic), 316
Ganglion, 279

Gasserian, 307

root of spinal nerve, 282
Gastric juice, 139
Glabella, 21

Gladiolus (body of sternum), 44
Glands of Bartholin, 352

Glands, ceruminous, 256, 329

digestive, 131

ductless, 262

Peyer's (or patches), 144

lacrimal, 343

lymph, 223

mammary, 260

Meibomian (tarsal), 342

prostate, 346

salivary, 134

sebaceous, 255

structure of, 8

sudoriferous, 256

tissue, 7
Glottis, 345
Graafian follicle, 349
Greenstick fracture, 56, 77
Glycogen, 168

Hair, 257

Hamstring tendons, 114, 115

Hearing, 329

Heart, 176

cycle of, 1 80

diastole of, 178

function of chambers, 180

muscle, 176

nerves of, 185

sounds, 182

systole of, 180

tendinous cords of, 178

valves of, 179
Hematin, 172
Hemoglobin, 172
Hemorrhage, 217

control of, 219

Hemorrhoidal arteries, 198, 199, 200
Hernia, 372

retro-peritoneal, 368
Hilus or hilum, 2

of kidney, 244

of lung, 236

of, spleen, 151
Hip-bone (os coxae), 48
Housemaid's knee, 82
Hydrocephalus, 303
Hymen, 352
Hyperemia, 229
Hyperpnea, 242
Hypodermoclysis, 214

INDEX

405

Hypophysis cerebri, 267
Hypothear muscles, 109

Ileum, 142, 143
Ilium (os), 48
Inflammation, 229
Inguinal rings, 371
Inorganic substances of bone, n
Insertion of muscles, 85
Inspiration, act of, 238
Instep (arches of foot), 73
Intercellular substance, 4
Intermuscular septa, 81
Interosseous spaces, 57, 66
Intestine, 139

large, 144

small, 141
Iris, 336
Isthmus of fauces, 133

Joint or articulation, 17
immovable, 17
motions of, 18
movable, 17
yielding, 18

Kidney, floating, 252
Kidneys, 244

Labia majora, 351

minora, 351

Labyrinth (ear), 331, 332
Lac teals, 168, 227
Lanugo, 257

Large vessels and nerves (location), 377
Larynx, 233
Leucocytes, 172, 173
Leukemia, 152
Ligament, annular, 109, 119

of Bigelow (Y) ileo-femoral, 69

broad, 350

crucial, 71

deltoid, 72

elastic, 42, 73

Gimbernat's, 372

inguinal (Poupart), 50, 81, 96

of liver, 150

orbicular, 64

of patella, 70, 112

sacro-sciatic, 50

Ligament, suspensory of lens, 337

transverse of ankle, 72
Ligaments of uterus, 350
Ligamentum nuchae, 43

teres, 69, 70
Linea alba, 96

aspera, 66

semilunaris, 95
Lineae transversae, 97
Liver, 148
Lochia, 358

Lumbo-sacral cord, 291
Lungs, 235
Lymph, 170, 223

capillaries, 221

corpuscles, 223

nodes (lymphatic glands), 223

origin of, 222

spaces, 221

vessels, 221
Lymphatic ducts, 223
Lymphocytes, 223
Lymphoid tissues, 9, 223

Malleolus, lateral, 65

medial, 65
Manubrium, 44
Marrow, 12
Mastication, 157
Meatus, external auditory, 329

of nose, 33, 233

of urethra, 247, 351
Median line, 2
Mediastinum, 365
Medulla (of brain), 302, 322
Medullary canal, 14
Medullated fibers, 277
Membranes, 7

of brain, 305

mucous, serous, synovial, 7

of spinal cord, 281
Menopause (climacteric), 349
Menstruation, 349
Mesentery, 147
Metabolism, 8, 270
Metastasis, 229
Micturition, 249
Milk, 261
Mons veneris, 351

406

INDEX

Motions of eyeball, 343
Moulding of head, 32
Mouth (oral cavity), 131

breathing, 239

Movable joint, description of, 1 7
Muscle band of His, 177

cell, 83, 122

tissue, 83, 119
Muscles, action of, 126

modifications, 125

of abdomen, 94-97

of back, 85

of breast, 103

of face (or of expression), 89-91

of head and neck, 86, 93

of lower extremity, 109

of mastication, 90

of pelvis, 109, no, in

of upper extremity, 101

ribbon, 92

stimulus of, 122

structure of, 83,

tension of, 120, 122
Myocardium, 176

Nails, 256
Nares, 34, 233
Nasal breathing, 239
Nasopharynx, 135
Necrosis (of bone), 13
Nerve centers, 279

cylinder, 278

plexus, 285

supply to joints, 74
to muscle groups, 128

tissue, 277
Nerves, cervical, 286

coccygeal, 294

cochlear, 333

cranial, 305

femoral, 292

lumbar, 291

motor, 279, 321

optic, 337

phrenic, 286

pneumogastric, 309

sacral, 292

sciatic, 292

sensory, 281,

Nerves, spinal, 284

thoracic, 291
Neurilemma, 278
Neuron, 277
Nose, 231
Notch, ethmoid, 21

intercondyloid, 65

radial, 57

sciatic, 49

sternal or jugular, 44

supraorbital, 21

Notes clinical, blood-vessels, 214, 216,
219

bones, 28, 34, 37, 38, 43, 56

digestive organs, 133, 139, 144
146, 151, 152

kidney, 248, 249, 250, 251

lymph system, 228, 229, 230

muscles, 88, 125 .

nerve system, 282, 303, 305, 309,

3i3

pelvic organs, 350, 357

regional, 363

respiratory, 237

skin, 255, 256, 258, 259

special senses, 326, 331, 338, 343

spleen, 152

Notes obstetric, 32, 50
Notes practical and special, blood-ves-
sels, 172, 175, 185, 193, 195, 197,

2OO, 212

bones, 57, 58, 66, 71, 73, 76, 78

muscles, Si, 90, 98, 103, 112, 121

regional, 361
Notes surgical, abscess, 100, 262

blood-vessels, 175, 193

bones, 28, 63, 72, 75, 78

digestive organs, 146

kidney, 248

muscles, 82, 117, 131, 262

nerves, 282, 304, 305, 308

regional, 363, 368
Nucleus and nucleolus, 4

caudate, 301

lentiform, 301
Nutrient artery, 15

Obturator membrane, 49
Olfactory region, 326

INDEX

407

Omentum, 148

Opsonic index, 220

Optic commissure (chiasm), 307

disc, 337

thalamus, 301
Orbit, 33

Organ and organic substance, 7, 8
Origin of blood cells, 172, 173

of muscles, 85
Os coxse or hip bone, 48
Osmosis, 170, 214, 229
Osseous tissue, 5, n
Ossicles, 332, 333
Ossification, 14
Ovary and ovum, 348, 349
Ovulation, 349

Palate, hard, 26, 131

soft, 131

Palm, or metacarpus, 59
Pancreas, 148, 263
Papilla of hair, 257

of skin, 254

tongue, 132
Parathyroids, 266
Patella, 68

Peduncles of brain, 303
Pelvic floor, no

girdle, 51

organs, 346
Pelvis, 51
Pepsin, 139
Peptones, 159, 160
Pericardium, 183
Perichondrium, 5
Perineal arteries, 200
Perineum, 353
Perineurium, 279
Periosteum, 13
Peristalsis, 147
Peritoneum, 367
Peri vascular spaces, 221
Perspiration, 258
Peyer's patches, 144
Phagocytes, 173, 214, 230
Phagocytosis, 173
Phalanges, 59
Pharynx, 134, 233
Physiology of blood, 213

Physiology of bone, 78

of brain, 311

of cord, 295

of digestive organs, 153

of kidneys, 248

of lymph system, 228, 230

of muscle, 119

of nerve system, 321

of ovary, 349

of respiratory organs, 237

of skin, 257

of sympathetic nerves, 318, 321

of uterus, 348, 357, 358
Pia mater of brain, 305

of cord, 281
Pillars of fauces, 133
Pituitary body (hypophysis), 267
Placenta, 212, 357

previa, 359
Plasma, 171, 173
Pleura, 236
Plexus, 285

brachial, 287

cardiac, 318

celiac, 318

cervical, 286

hypogastric, 318

lumbar, 291

pulmonary, 318

sacral, 292
Pons varolii, 303
Popliteal plane, 66

space, 114, 371
Porta of liver, 148
Portal vein, 209
Pouch of Douglas, 353
Pregnancy, 357
Process (def.) 13

acromion, 55

alveolar, 26, 27

articular, 39

coracoid, 5 5

coronoid, 57

frontal, 26

mastoid, 22

odontoid, 40

olecranon, 57

palate, 26

pterygoid, 24

408

[NDEX

Process, spinous, 39

styloid, 23
of fibula, 66
of radius, 57
of ulna, 57

transverse, 39

unciform, 58

zygomatic, 26
Promontory, 42
Pronation, 64
Proteids, 153 154
Protoplasm, 4
Ptyalin, 134, 158
Puberty, 349
Pubic arch, 49

symphysis, 49
Pudendum, 351
Pulse, 181
Pylorus, 138
Pyramids and tracts (medulla), 302

decussation of, 302

Rachitis, 77

Receptaculum chyli, 223
Reciprocal reception, 63
Rectum, 146
Reference tables, 379
Reflex, abdominal, 297

action, 296

patellar, 297

plantar, 297

skin, 297

tendon, 297
Rennin, 139
Respiration, 231

artificial, 242

external, 231

influence of drugs, 241

internal, 231

modifications of, 242

rate of, 238, 239

stimuli, 240, 241

variations, 240, 241,
Respiratory sounds, 239
Retina, 337
Ribs, 44
Rigor mortis, 1 24

Sacrum, 41
Saddle joint, 19, 63

Saliva, 134

Sartorius or "tailor muscle," 112

Scalp, 360

Scarpa's triangle, 370

Schneiderian membrane, 233, 326

Sclera, 335

Scorbiculus cordis, 366

Scrotum, 353

Secreting organs, 7, 269

Secretions, 7, 269

internal, 263, 269
Semilunar notch, 57
Septum, 34

intermuscular, 81

nasal, 34, 232
Serum, 217, 218
Sheath of rectus, 97
Shoulder girdle, 56
Sigmoid groove, 22, 305
Sight, 335
Sinus (def.), 2

ethmoid, 23

frontal, 21

of kidney, 245

maxillary, 25

sagittal, 22

sphenoid, 24

transverse (lateral), 22, 204
Sinusitis, 35
Skeleton, 15

at different ages, 75
Skin, 253
Skull, as a whole, 29

at birth, 32

completion of, 75

points of interest, 29
Smell, 326
Special senses, 325
Speech, 312, 345
Spermatic cord, 354
Sphincter, anal, 146

cardiac, 138

ileo-colic, 143

pyloric, 138

vesical, 247
Spina bifida, 77
Spinal canal, 42, 43

column, 43

cord, 280, 321, 322

INDEX

409

Spinal curves, 44
Spine (def.), 13

intercondyloid, 65

of ilium, 48

of ischium, 49

of pubes, 49

of scapula, 55

of tibia, 65

Splanchnic nerves, 318
Spleen, lien, 151, 264
Spongy or cancellous tissue, 1 2
Sternum, 44
Stomach (gaster), 137

of infant, 139
Straits of pelvis, 51
Summary, cerebro-spinal nerves, 310

functions of cranial nerves, 314

nerve system, 321

return of lymph, 228

return of venous blood, 207, 208

spinal nerves, 295
Supination, 64
Sutures, 24

Sympathetic (autonomic) nerves, 316
Symphysis pubis, 49, 50
System (def.), 8

Tactile cells, 327
Tables of skull, 29
Tarsus, 67

meta, 68
Taste, 133, 328
Teeth, 35

eruption of, dentition, 36
Temperature of body, 274, 275
Tendinous cords, 198
Tendon of Achilles or tendo calcaneus,

68, 118

Tendons, 84, 85
Tentorium cerebelli, 305
Terminal filament, 280
Testes, 353

Thenar eminences, 109
Thorax, 363
Thrombin, 218
Thymus body, 266
Thyroid (thyreoid) body, 265
Tissues, 4

contractile, 83

Tissues, fluid, 9
Tissue spaces, 80
Tongue, 131, 132
Tonsil, 133

lingual, 133

palatine, 133

pharyngeal, 135
Touch, 327
Trachea, 234
Triangles of neck, 362
Trigone, bladder, 247

femoral, 200, 370
Trochanters, 66
Trochlea, 56
Trophic centers, 297
Trunk, 17, 44

Tuber ischii (tuberosity), 49
Tuberosity of calcaneus, 67
Tympanum, 330

Umbilical artery, 201

cord, 212

vein, 210
Umbilicus, 96
Urea, 249
Ureter, 247
Urethra, 247
Urethral caruncle, 248
Urination (micturition), 249
Urine, 249

Uterine tubes (Fallopian), 348
Uterus, 346
Uvula, 131

Vagina, 350

Vaginal synovial membranes, 107

Valve, Eustachian, of heart, 210

Houston's, 146

ileo-cecal, 145
Valves of heart, 179

of veins, 175
Vasa vasorum, 176
Vaso motor nerves, 3 20
Vein, jugular, 204

portal, 209

umbilical, 209, 210
Veins, 203

azygos, 206

structure, 175

410 [NDEX

Velum palati, 131 Vitreous layer (cranial bones), 29

Vena cava inferior, 208 Viscera, abdominal, 367

superior, 206 thoracic, 365

Ventilation, 243 "Vital knot" (noeud vital), 314

Ventricles of brain, 303 Vocal bands and voice, 345

of heart, 177 Vola, palm, 74
Vermis (of cerebellum), 302

Vertebrae, 39, 40, 41 Wharton's jelly, 212
Vertebral aponeurosis, 86

Vertex of skull, 29 Xyphoid appendix, 44
Vestibule (ear), 331

(pudendum), 351 Y-ligament, 70
Villi, 141, 142

Vitreous body, 337 Zygoma (process), 22

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