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Charles Field Mason.

A complete handbook for the sanitary troops of the U. S. army and navy and national guard and naval militia online

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as a " Pott's fracture."

The ankle joint is made up of the tibia and fibula
above and the astragalus below ; it is a strong joint,
so much so that while it is frequently subjected to
violent wrenches and strains, dislocation seldom
occurs; under such conditions the joint surfaces do
not slip entirely away from each other, but the liga-
ments and synovial membrane are torn and blood
is poured out into and about the joint, constituting
the condition known as sprain.

Beyond the ankle is the foot, composed of the
larsus, metatarsus, and phalanges. The tarsus, be-
sides the astragalus, already referred to as helping
to form the ankle joint, contains the os calcis or
heel bone, and five other small bones, making, seven
in all.

The metatarsus lies in that part of the foot just
behind the toes, and is composed of five long bones.
The phalanges or toe joints are so called because " 9 Flbuia.' a '
they are arranged in phalanx or rows; there are
three for each toe except the great toe which has only two.

To go back to the vertebral column. Connected with its dorsal
portion are twelve ribs on each side, and closing in the space between
the ribs in front so as to form the thorax is the breast bone or
sternum.

It is scarcely necessary to say that the number of ribs is the same
in man as in woman, though there is an old tradition that Adam lost
one rib in order to gain a wife. The seven upper ribs are connected
directly to the sternum in front by their cartilages and are known as
true ribs; the fire remaining are known as false ribs, and the last two
which are not connected with, those above are known as floating ribs.
The breast bone or sternum is composed of three parts and extends



THE SKELETON AND JOINTS



43



from the root of the neck to the pit of the stomach. The thorax or
chest so formed is a bony cage which encloses and protects the heart
and lungs ; it is separated from the abdomen by a broad, muscular
partition, arching upward and known as the diaphragm.

Connected with the thorax is the upper extremity composed of
the shoulder and shoulder joint, arm, elbow joint, forearm, tvrist
joint, and hand.

The shoulder is composed of the clavicle or collar bone and the
scapula or shoulder blade. The clavicle (Fig. 10) is a very strong




FIG. 10. Clavicle.

bone with a double curve like the Italic letter j. It is connected at
one end with the breast bone and at the other with a process of the
shoulder blade known as the acromion; it is the acromion process
which we feel just under the skin at the point of the shoulder. The
clavicle notwithstanding its strength
is very frequently broken owing to
its fixed position and the fact that
it receives the jars transmitted
through the upper extremity when
one tries to save himself in falling
by throwing out the arm. The
scapula (Fig. n) is a freely mov-
able flat bone connected at one end
with the collar bone to form the
arch of the shoulder; its outer
angle or head contains a shallow,
saucer-shaped depression known as
the glen oid cavity for the reception
of the head of the humerus to form
the shoulder joint. The shoulder,
like the hip, is a ball-and-socket
joint, but unlike the hip, the socket
is very shallow, so that the head of the humerus in the very free
motion permitted easily rolls over the edge and becomes dis-




FIG. 1 i. Scapula.



44



ANATOMY AND PHYSIOLOGY



located; as a matter of fact dislocation at the shoulder joint is
many times more frequent that at all the other joints of the body
put together, so that in obscure injuries to the shoulder we always
look for dislocation.

The arm is that portion of the upper extremity which lies between
the shoulder and elbow ; like the thigh it contains but one bone, the
humcrus (Fig. 12). The upper end of the humerus
consists of the head and the tuberosities, the anatomical
neck lying between the two, and the surgical neck
being the constricted portion of the shaft just below
the tuberosities; the surgical neck is so called because
it is the part most frequently broken.

The lower end of the humerus is expanded to form
the elbow joint and has a projection on each side
known as a condyle.

The elbow joint is made up of the humerus and the
two bones of the forearm, the radius
and ulna (Fig. 13).

The radius lies on the outer side of
the arm and is so called because it
radiates about its fellow in the mo-
tion of pronation, in which the palm
of the hand is turned down, and
supination, in which the palm is
turned up. The radius has a small
head which takes but little part in the
elbow joint, but a large lower end
which with the carpus forms the wrist
joint to the entire exclusion of the
ulna. It is because of the radius resisting almost
alone the force of falls upon the hand that it is
broken so much more often than the ulna. Such a
break just above the wrist joint is very common
and is known as a " Colles's fracture."

The ulna has its upper end most highly developed,
forming a projection which extends back behind the
elbow joint, protecting it in the same manner as the
patella does the knee joint. This protection forms . I3 _ Ra d; US and
the " point of the elbow " and is called the olecranon.



FIG. 12. Hu-
merus.




Ulna.



45



The wrist or carpus is composed of eight small bones in two
rows of four each, the upper row together with the lower end of
the radius forming the wrist joint. The hand is composed of the
five metacarpal bones, while the fingers have three rows of phalanges,
except the thumb which has two only.

Balanced on the top of the spinal column and forming a joint with
its uppermost vertebra is the skull (Fig. 14). The skull is usually
considered in two parts,
the cranium which con-
tains the brain, and the
face. The cranium is that
part which lies above a
line drawn from the nape
of the neck through the
ears to above the eyebrows,
and the brain here lies
everywhere in contact with
the bone so that a fracture
of the cranium like one of
the spine, derives its spe-
cial seriousness from the
accompanying injury to the
brain. In front, however,
just over the eyes, the two
plates of which the cranial
bones 'are composed separate to leave a space known as the frontal
sinuses; here fractures of the outer plate may occur without injury
to the brain. The cranium varies in thickness from about that of
paper at the temples to a quarter of an inch or more behind.

The visible portion of the cranium is composed of six bones, the
frontal in front, the occipital behind, the two parietals on the top, and
the two temporals on the sides. In the lower part of the occipital
bone is a large round hole known as the foramen magnum through
which the spinal cord makes connection with the brain.

The face is composed of fourteen bones, arranged mostly in pairs,
and forming the two orbits, the nose, and mouth. The only facial
bones necessary to remember are the two, tiny, nasal bones which
form the arch of the nose, and the two superior maxillary bones and




FIG. 14. Skull, a, Nasal bones; b, superior
maxilla; c, inferior maxilla; d, occipital bone;
e, temporal bone; /, parietal bone; g, frontal bone.



46



ANATOMY AND PHYSIOLOGY



the inferior maxillary bone which contain the teeth and enclose the

mouth.

The inferior maxillary is the only movable bone of the face; its

joints with the upper jaw lie just in front of the ear where the head

of the bone can be felt to move when the mouth is opened.

The teeth appear in two crops ; the first, ten in number in each

jaw, are known as the milk teeth; at the end of the sixth year they
begin to be replaced by the permanent teeth, six-
teen in each jaw. The second dentition is not
concluded until about the twenty-first year when
the wisdom teeth or last molars appear.

Every tooth has a crown the part above the
gum, a neck, the constricted portion just below
the crown, and a root, the part embedded in the
jaw. In structure (Fig. 15) they are composed
of enamel, the hard surface covering, the dentine
which comprises the mass of the tooth, the cement
which covers the root, and the pulp composed

of nerves and blood-vessels which nourishes the tooth and lies in its

interior. When the teeth are not properly cared for the protective




FIG. 15. Section of
Lower Molar, a. Den-
tine; b, enamel; c,
crusta petrosa; d, pulp
cavity.





Canine or Eye Second Eicus- Central Incisor Second Molar of
Tooth of Upper pid of Lower of Upper Jaw. Upper Jaw.

Jaw. Jaw.

FIG. 1 6.



Wisdom Tooth
of Upper Jaw.



enamel cover breaks down, exposing the detine which rapidly
decays, undermining the enamel and finally exposing the sensitive
pulp; pain then begins, and unless the tooth is filled death of the
pulp occurs and the tooth is lost.

The four front teeth in each jaw are adapted to cutting and are
calkd incisors; next to these on each side is a tearer or canine tooth,
and then two bicuspids; all of these usually have a single root. After
the bicuspids come three molars or grinders on each side. The up-



THE SKELETON AND JOINTS 47

per molars usually have three roots, two on the outer side and one
on the inner, while the lower molars generally have two roots. A
knowledge of the number and arrangement of the roots of the teeth
is necessary in order to select the proper pair of forceps to use in
tooth extraction (Fig. 16).



CHAPTER II



THE MUSCLES, CELLULAR TISSUE, AND THE SKIN

MUSCLES are simply lean meat. Each muscle is composed of a
number of fibers held together by connective tissue, and collected
into bundles which are enclosed in a sheath of fibrous tissue known
as fascia.

The function of muscles is to contract and thereby
move the various parts and tissues of the body;
their tendency to contract is constantly present dur-
ing life, so that if a muscle is cut the two ends at
once pull apart and a gaping wound is left. Foi
the same reason if a bone is broken the contracting
muscles on each side of the fracture have a tendency
to shorten the limb, making the ends of the bone
override each other and produce deformity (Fig.
17). It is this muscular contraction which must be
overcome in setting fractures or reducing disloca-
tions.

As muscles taper toward the ends they become
more and more fibrous until white, glistening ten-
dons or sinews are formed which finally blend with
the periosteum at the point of attachment to* bone.
Most muscles, like those of the limbs, are under
the control of the will and are known as voluntary
muscles (Fig. 18), while others, like those of the
heart and intestinal tract, are entirely involuntary.
This involuntary action of the important muscles
which preside over the necessary functions of life
is a wise provision of nature; otherwise one might
forget to breathe or make the heart beat, and sleep
would be out of the question.

The muscles in their action upon the bones produce various
special motions ; bending a limb is called flexion, straightening it is
extension; turning the palm down is pronation, turning it up supi-

(48)




muscular



MUSCLES, CELLULAR TISSUE AND SKIN 49

i

nation; motion of the limb on its long axis is rotation. Abduction is
throwing a limb out from the body, while drawing it toward the
body is adduction.




FIG. 18. Superficial Layer of Voluntary Muscles.

In a variable time after death rigor mortis sets in, a change in the
muscles by which they become rigid, and remain so until decomposi-
tion begins. When the person has undergone great muscular exer-



50 ANATOMY AND PHYSIOLOGY

tion to the point of exhaustion just before death this change takes
place almost immediately, so that the soldier killed in battle may be
found rigidly fixed in the same position in which he met his death.

The only voluntary muscles which it is necessary for you to re-
member are the stcrno-mastoid, the biceps, and the diaphragm. Im-
portant involuntary muscles are the heart, stomach, and bladder.

The stcrno-mastoid is the prominent muscle seen on each side of
the neck when the head is turned in the opposite direction and ex-
tending from behind the ear to the top of the sternum ; its front edge
is a guide to the carotid artery. The biceps is the big muscle on the
front of the arm, familiar to all, and the inner border of which is a
guide to tRe brachial artery.

The diaphragm is the great muscular partition between the thorax
and abdomen.

The connective or cellular tissue, so called because of the spaces
contained in its spongy structure, connects together all the other
special tissues, and serves as a support for the blood-vessels, nerves,
and fat.

The fat is the padding which fills in empty spaces and gives form
and pleasing outlines to the body. Its important functions are to
serve as a reserve of nutritive material for emergencies, and to act
as a blanket in retaining the bodily heat. The emaciation which
follows an exhausting illness is largely due to the using up of the
reserve fat, and everyone is familiar with the fact that a fat person
stands cold better and heat less well than a thin one.

The skin is a tough, elastic membrane which covers the entire
body and is continuous at the various orifices with the mucous
membrane. Anatomically it consists of two layers, the cuticle, and
the derma or true skin. The cuticle is that part which is raised when
a blister occurs and which peels off after scarlet fever.

The derma constitutes the greater part of the thickness of the
skin, and contains the blood-vessels, nerves, sabaceous and sweat
glands.

The appendages of the skin are the hair and the nails which are
modified cuticle (Fig. 19).

The sebaceous glands secrete an oily substance which gives to the
skin its softness and pliability ; the orifices of the ducts of the se-
baceous glands are particularly large about the face and nose, and
when plugged with dirt form the familiar black-heads.



MUSCLES, CELLULAR TISSUE AND SKIN



51



f he sweat glands are in vast numbers all over the body and their
orifices constitute what are known as the pores. They secrete a
variable amount of water, averaging about two pints a day, and the
water contains organic matter and salts, and constitutes the perspira-
tion or sweat.

The functions of the skin are to protect the underlying parts from
injury, from the invasion of bacteria, and from undue evaporation ;




FIG. 19. Perpendicular Section of the Skin, showing: a, The epidermis, cuticle, or icarf
skin; b, a layer of dark-colored cells; c, the papillae on the surface of d, the coriutn, derma,
cutis vera, or true skin, and e, the fat cells underlying it; /, a perspiratory pore or aper-
ture, g, the duct, and h, the coiled substance of a sudoriparous gland; t, the shaft of a hair,
k, its root, and /, sebaceous glands communicating with the interior of the hair follicle.

to receive the nerve ends and thereby serve as a special organ of
touch ; and through the agency of the sweat glands to act as an im-
portant excretory apparatus and a regulator of bodily temperature.

The importance of a whole skin as a protection against the bacteria
of disease is well known ; subcutaneous wounds, that is, contusions,
give us little anxiety, but if the skin is broken special dressings must
be applied to take its place. Plague frequently invades the body
through a break in the protective wall of the skin and syphilis is
contracted in the same manner.

The excretory function of the skin, by which it throws off poison-
ous waste products dissolved in the perspiration, is illustrated by
what happens in extensive superficial burns by which this function
of the skin is destroyed; the man becomes poisoned by his own
waste products and death is the result.



52 ANATOMY AND PHYSIOLOGY

As a temperature regulator its action is shown by the increased
perspiration in hot weather, the evaporation of the water serving to
cool the body ; conversely in winter perspiration is imperceptible.

The skin has also absorbing powers; thirst may be allayed by
prolonged immersion in a bath ; the vapor of mercury and even
metallic mercury may be taken up through the unbroken skin.



CHAPTER III

THE NERVOUS SYSTEM AND SPECIAL SENSES

THE nervous system consists of the brain, spinal cord, and the
nerves constituting the cerebro-spinal system, and the ganglia and
connecting nerves composing the sympathetic system.

The brain situated within the cranium is the steat of the intellect
and will, and the great headquarters telegraph office from which all
the orders for motion are sent out and to which all the reports called
sensations are forwarded. The spinal cord extends downward from
the brain through the spinal canal and is largely an aggregation of
nerves or wires connecting the brain with all parts of the body.
The ganglia (Fig. 20) are small masses of nervous matter arranged
in pairs along the spinal column and in groups about the heart and
great viscera; they are connected with each other and with the
cerebro-spinal system, and their distribution is to the heart, lungs,
blood-vessels, the gastro-intestinal tract, and the great viscera.

The nerves are composed of bundles of minute tubules enclosed
in a protective sheath, each of these tubules corresponding to a tele-
graph wire and ultimately reaching its destination without branching.

The brain (Fig. 21) consists of the cerebrum and cerebellum, and
pons and medulla. The cerebrum is the soft, pulpy, oval mass which
is seen when the top of the cranium is removed ; it is divided from
before backward by a deep fissure, almost, but not quite complete,
so that there is a bridge left connecting the two halves.

The surface of the brain presents numerous grooves or sulci, be-
tween which are the convolutions. The exterior is composed of gray
matter, and the interior of ichite matter, the latter being nothing
more than a collection of nerves connecting the various parts of the
brain with each other and with the spinal cord. In the interior of
the cerebrum are a number of cavities known as ventricles. The
gray matter is the seat of the mind.

The brain is very delicate and easily injured; injuries or even
slight pressure seriously interfere with its functions. So when a

(53)



54



ANATOMY AND PHYSIOLOGY



fracture of the skull occurs with depression of bone, or even a slight
bleeding from one of the cerebral vessels, pressure on the brain




FIG. 20. Sympathetic System of Ganglia and Nerves.

results and we have unconsciousness or paralysis or both ; this is
the condition in apoplexy which is merely a hemorrhage within the
cranium ; as the blood cannot escape it must produce pressure.



THE NERVOUS SYSTEM AND SPECIAL SENSES 55

Lining the interior of the cranium is a strong fibrous membrane
which protects and suspends the brain and is called the dura mater;
this with the pia mater and arachnoid constitute the meninges or
membranes, inflammation of which is known as meningitis.

If we lift up the back part of the cerebrum we see below it a
small mass of nervous tissue known as the cerebellum or little brain
(Fig. 22). It is chiefly concerned with the maintenance of the
equilibrium of the body.




FIG. 21. The Hemispheres of the Brain. A, The right; B, the left divided from before
backward by a, b, the longitudinal fissure, and connected by c, the bridge of transverse
fibers called the corpus callosum. On, the right side the convolutions and sulci are shown;
on the left the upper part of the convexity of the hemisphere has been cut away to show
the gray matter d, d, dipping into the sulci and; appearing as islands, e, e, in the interior
of the white matter; the elongated cavity with curved extremities is the lateral ventricle
of that side.

The pons is the connecting link between the cerebrum and me-
dulla and between the two lobes of the cerebellum.

The medulla oblongata is the enlarged upper end of the spinal
cord lying just within the cranium, and containing the important
nerve centers presiding over the action of the heart and lungs. It
is also the part in which the nerves coming from each side of the
brain cross over to the opposite side of the spinal cord, so that an
injury of the brain above this crossing causes a paralysis on the
opposite side of the body.

The spinal cord (Fig. 23), like the brain, is enclosed in mem-
branes and is a tail-like column of nervous tissue composed chiefly
of nerves but containing in its interior a central column of gray



56



ANATOMY AND PHYSIOLOGY



matter. A pair of nerves leave it opposite each vertebra, those of
the cervical region being arranged in two groups. The upper group
supplies the face and neck and the interior of the chest; one of the
most important of the branches is the phrenic, which controls the
movements of the diaphragm. The lower group is known as the
brachial plexus and supplies the upper extremity.




FIG. 22. Lower Surface of Brain. C, Cerebellum; M, medulla; P, pons.

The dorsal nerves supply the chest wall, those of the lumbar and
sacral regions go to the pelvis and lower extremities ; one great cord
which emerges from the pelvis on each side and passes down the
back of the thigh is called the sciatic nerve; it is often the seat of
the neuralgic pain known as sciatica.

As all the nerves of the body except those of the face must pass
through the spinal cord on their way to the brain it is evident that if
the spinal cord is cut completely across there must be paralysis of all
the parts below ; such a paralysis is called paraplegia. If the injury
is high enough up the nerves controlling the action of the heart and



THE NERVOUS SYSTEM AND SPECIAL SENSES 57



lungs are involved and death quickly follows. As the motor nerves
are collected in the front part of the spinal cord and the sensory
nerves in the back part, a
partial injury of the cord
may cause paralysis of mo-
tion without affecting sen-
sation, or vice versa.

There are two kinds of
nerve tubules, motor and
sensory. The former con-
vey from the brain orders
directing motion, while the
latter carry to the brain in-
formation as to sensation.
If a motor nerve is cut the
muscles supplied by it are
paralyzed because orders
from the brain can no
longer reach them; if a
sensory nerve is cut sensa-
tion is lost in the part sup-
plied by it because infor-
mation as to the sensory
condition of the part can
no longer reach the brain.
Usually nerves contain both
motor and sensory fibers,
but some nerves, like the
facial, are purely motor.

There are certain reports
and impressions which are
sent by way of the nerves
from various parts of the

body which it is not neCCS- FIG. 23. Spinal Cord and Nerves.

sary to refer to the brain for its action ; the necessary action is pro-
vided automatically by what is called reflex action.




58



ANATOMY AND PHYSIOLOGY




The quick withdrawal of the hand when it touches something
hot and the rhythmical contraction of the heart under the stimulus
of its distention with blood are instances of reflex or automatic

action originating respectively in
the gray matter of the spinal cord
and ganglia.

The special senses are touch,
taste, smell, hearing, and sight.
The three latter are presided over
by special cranial nerves, that is,
nerves coming directly from the
brain without passing through the
spinal cord.

The sense of touch is resident in
the skin generally, but is most
'^^ A nif ,-t highly developed in the ends of the

G. 24. Section of Nose. A. Olfactory J
nerves. fingers.

The sense of taste is located in the mouth, more especially in the
tongue; for its action it is necessary that the substance should be
in solution ; this is in' accordance with our knowledge that insoluble
medicines are tasteless.

The ' sense of
smell resides in the
upper nasal cavi-
ties where the fila-
ments of the olfac-
tory nerve are dis-
tributed to the
mucous membrane
(Fig. 24).

Hearing or the
perception of
sound vibrations is
provided for by
the ear through
the auditory nerve.

yyjgy

1 he ear (rig. 25)p, G 25 Section of the Ear. B, External ear; M, auditory canal;
consists of the ex- ^' t y m P !LTlum ' ?> middle ear; H, ossicles; , Eustachian tube.




THE NERVOUS SYSTEM AND SPECIAL SENSES 59

ternal ear, the auditory canal, the tympanum or drum membrane,
the middle ear, stretching across which are the small bones or
ossicles, and the internal ear. The tympanum is stretched like
a drum-head across the auditory canal, separating the external and
middle ears ; in order that the air pressure on the two sides of the
drum may be equalized there is an air tube leading from the middle



Online LibraryCharles Field MasonA complete handbook for the sanitary troops of the U. S. army and navy and national guard and naval militia → online text (page 5 of 38)