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Hygienic Physiology

J >> Joel Dorman Steele >> Hygienic Physiology




GROWTH OF THE BONES.--By means of this system of canals, the blood
circulates as freely through the bones as through any part of the body,
The whole structure is constantly but slowly changing, [Footnote: Bone is
sometimes produced with surprising rapidity. The great Irish Elk is
calculated by Prof. Owen to have cast off and renewed, annually in its
antlers eighty pounds of bone.] old material being taken out and new put
in. A curious illustration is seen in the fact that if madder be mixed
with the food of pigs, it will tinge their bones red.

REPAIR OF THE BONES.--When a bone is broken, the blood at once oozes out
of the fractured ends. This soon gives place to a watery fluid, which in a
fortnight thickens to a gristly substance, strong enough to hold them in
place. Bone matter is then slowly deposited, which in five or six weeks
will unite the broken parts. Nature, at first, apparently endeavors to
remedy the weakness of the material by excess in the quantity, and so the
new portion is larger than the old. But the extra matter will be gradually
absorbed, sometimes so perfectly as to leave no trace of the injury. (See
p. 271.)

A broken limb should be held in place by splints, or a plaster cast, to
enable this process to go on uninterruptedly, and also lest a sudden jar
might rupture the partially mended break. For a long time, the new portion
consists largely of animal matter, and so is tender and pliable. The
utmost care is therefore necessary to prevent a malformation.

THE JOINTS are packed with a soft, smooth cartilage, or gristle, which
fits so perfectly as to be airtight. Upon convex surfaces, it is thickest
at the middle, and upon concave surfaces, it is thickest at the edge, or
where the wear is greatest. In addition, the ends of the bones are covered
with a thin membrane, the _synovial_ (_sun_, with; _ovum_,
an egg), which secretes a viscid fluid, not unlike the white of an egg.
This lubricates the joints, and prevents the noise and wear of friction.
The body is the only machine that oils itself.

The bones which form the joint are tied with stout ligaments (_ligo_,
I bind), or bands, of a smooth, silvery white tissue, [Footnote: The
general term _tissue_ is applied to the various textures of which the
organs are composed. For example, the osseous tissue forms the bones; the
fibrous tissue, the skin, tendons, and ligaments.] so strong that the
bones are sometimes broken without injuring the fastenings.

II. CLASSIFICATION OF THE BONES.

For convenience, the bones of the skeleton are considered in three
divisions: the _head_, the _trunk_, and the _limbs_.

1. THE HEAD.

THE BONES OF THE SKULL AND THE FACE form a cavity for the protection of
the brain and the four organs of sense, viz.: sight, smell, taste, and
hearing. All these bones are immovable except the lower jaw, which is
hinged [Footnote: A ring of cartilage is inserted in its joints, something
after the manner of a washer in machinery. This follows the movements of
the jaw, and admits of freer motion, while it guards against dislocation.]
at the back so as to allow for the opening and shutting of the mouth.

THE SKULL is composed, in general, of two compact plates, with a spongy
layer between. These are in several pieces, the outer ones being joined by
notched edges, sutures (su'tyurs,), in the way carpenters term
dovetailing. (See Fig. 4.)

FIG. 4.

[Illustration: _The Skull._--1. _frontal bone;_ 2, _parietal bone;_
3, _temporal bone;_ 4, _the sphenoid bone;_ 5, _ethmoid bone;_ 6,
_superior maxillary (upper jaw) bone;_ 7, _malar bone;_ 8, _lachrymal
bone;_ 9, _nasal bone;_ 10, _inferior maxillary (lower jaw) bone._]

The peculiar structure and form of the skull afford a perfect shelter for
the brain--an organ so delicate that, if unprotected, an ordinary blow
would destroy it. Its oval or egg shape adapts it to resist pressure. The
smaller and stronger end is in front, where the danger is greatest.
Projections before and behind shield the less protected parts. The hard
plates are not easy to penetrate. [Footnote: Instances have been known
where bullets, striking against the skull, have glanced off, been
flattened, or even split into halves. In the Peninsular Campaign, the
author saw a man who had been struck in the forehead by a bullet which,
instead of penetrating the brain, had followed the skull around to the
back of the head, and there passed out.] The spongy packing deadens every
blow. [Footnote: An experiment resembling the familiar one of the balls in
Natural Philosophy ("Steele's Popular Physics," Fig. 6, p. 26),
beautifully illustrates this point. Several balls of ivory are suspended
by cords, as in Fig. 5. If A be raised and then let fall, it will transmit
the force to B, and that to C, and so on until F is reached, which will
fly off with the impulse. If now a ball of spongy bone be substituted for
an ivory one anywhere in the line, the force will be checked, and the last
ball will not stir.] The separate pieces with their curious joinings
disperse any jar which one may receive, and also prevent fractures from
spreading.

FIG. 5.

[Illustration]

The frequent openings in this strong bone box afford safe avenues for the
passage of numerous nerves and vessels which communicate between the brain
and the rest of the body.

FIG. 6.

[Illustration: _The Spine; the seven vertebræ of the neck, cervical; the
twelve of the back, dorsal; the five of the loins, lumbar;_ a, _the
sacrum, and_ b, _the coccyx, coming the nine "false vertebræ."_
(p. 3).]

2 THE TRUNK.

THE TRUNK has two important cavities. The upper part, or _chest_,
contains the heart and the lungs, and the lower part, or _abdomen_,
holds the stomach, liver, kidneys, and other organs (Fig. 31). The
principal bones are those of the _spine_, the _ribs_, and the
_hips_.

THE SPINE consists of twenty-four bones, between which are placed pads of
cartilage. [Footnote: These pads vary in thickness from one fourth to one
half an inch. They become condensed by the weight they bear during the
day, so that we are somewhat shorter at evening than in the morning.
Their elasticity causes them to resume their usual size during the night,
or when we lie down for a time.] A canal is hollowed out of the column
for the safe passage of the spinal cord. (See Fig. 50.) Projections
(processes) at the back and on either side are abundant for the attachment
of the muscles. The packing acts as a cushion to prevent any jar from
reaching the brain when we jump or run, while the double curve of the
spine also tends to disperse the force of a fall. Thus on every side the
utmost caution is taken to guard that precious gem in its casket.

THE PERFECTION OF THE SPINE surpasses all human contrivances. Its various
uses seem a bundle of contradictions. A chain of twenty-four bones is made
so stiff that it will bear a heavy burden, and so flexible that it will
bend like rubber; yet, all the while, it transmits no shock, and even
hides a delicate nerve within that would thrill with the slightest touch.
Resting upon it, the brain is borne without a tremor; and, clinging to it,
the vital organs are carried without fear of harm.

FIG. 7.

[Illustration: B, _the first cervical vertebra, the atlas;_ A, _the
atlas, and the second cervical vertebra, the axis;_ e, _the odontoid
process;_ c, _the foramen._]

THE SKULL ARTICULATES with (is jointed to) the spine in a peculiar manner.
On the top of the upper vertebra (atlas [Footnote: Thus called because,
as, in ancient fable, the god Atlas supported the world on his shoulders,
so in the body this bone bears the head.]) are two little hollows
(_a_, _b_, Fig. 7), nicely packed and lined with the synovial
membrane, into which fit the corresponding projections on the lower part
of the skull, and thus the head can rock to and fro. The second vertebra
(axis) has a peg, _e_, which projects through a hole, _c_, in
the first.

FIG. 8.

[Illustration: _The Thorax or Chest._ a, _the sternum;_ b _to_ c, _the
true ribs;_ d _to_ h, _the false ribs;_ g, h, _the floating ribs;_ i, k,
_the dorsal vertebræ._]

The surfaces of both vertebræ are so smooth that they easily glide on each
other, and thus, when we move the head side wise, the atlas turns around
the peg, _e_, of the axis.

THE RIBS, also twenty-four in number, are arranged in pairs on each side
of the chest. At the back, they are all attached to the spine. In front,
the upper seven pairs are tied by cartilages to the breastbone (sternum);
three are fastened to each other and to the cartilage above, and two, the
floating ribs, are loose.

The natural form of the chest is that of a cone diminishing upward. But,
owing to the tightness of the clothing commonly worn, the reverse is often
the case. The long, slender ribs give lightness, [Footnote: If the chest
wall were in one bone thick enough to resist a blow, it would be unwieldy
and heavy As it is, the separate bones bound by cartilages yield
gradually, and diffuse the force among them all, and so are rarely
broken.] the arched form confers strength, and the cartilages impart
elasticity,--properties essential to the protection of the delicate organs
within, and to freedom of motion in respiration. (See note, p. 80.)

FIG. 9.

[Illustration: _The Pelvis._ a, _the sacrum;_ b, b, _the right
and the left innominatum._]

THE HIP BONES, called by anatomists the innominata, or nameless bones,
form an irregular basin styled the _pelvis_ (_pelvis_, a basin).
In the upper part, is the foot of the spinal column--a wedge-shaped bone
termed the _sacrum_ [Footnote: So called because it was anciently
offered in sacrifice.] (sacred), firmly planted here between the
widespreading and solid bones of the pelvis, like the keystone to an arch,
and giving a steady support to the heavy burden above.

3. THE LIMBS.

TWO SETS OF LIMBS branch from the trunk, viz.: the upper, and the lower.
They closely resemble each other. The arm corresponds to the thigh; the
forearm, to the leg; the wrist, to the ankle; the fingers, to the toes.
The fingers and the toes are so much alike that they receive the same
name, _digits_, while the several bones of both have also the common
appellation, _phalanges_. The differences which exist grow out of
their varying uses. The foot is characterized by strength; the hand, by
mobility.

FIG. 10.

[Illustration: _The Shoulder Joint._ a, _the clavicle;_ b,
_the scapula._]

1. THE UPPER LIMBS.--THE SHOULDER.--The bones of the shoulder are the
collar bone (clavicle), and the shoulder blade (scapula). The
_clavicle_ (_clavis_, a key) is a long, slender bone, shaped
like the Italic _f_. It is fastened at one end to the breastbone and
the first rib, and, at the other, to the shoulder blade. (See Fig. 1.) It
thus holds the shoulder joint out from the chest, and gives the arm
greater play. If it be removed or broken, the head of the arm bone will
fall, and the motions of the arm be greatly restricted. [Footnote: Animals
which use the forelegs only for support (as the horse, ox, etc.), do not
possess this bone. "It is found in those that dig, fly, climb and seize."]

THE SHOULDER BLADE is a thin, flat, triangular bone, fitted to the top and
back of the chest, and designed to give a foundation for the muscles of
the shoulder.

THE SHOULDER JOINT.--The arm bone, or _humerus_, articulates with the
shoulder blade by a ball-and-socket joint. This consists of a cup-like
cavity in the latter bone, and a rounded head in the former, to fit it,--
thus affording a free rotary motion. The shallowness of the socket
accounts for the frequent dislocation of this joint, but a deeper one
would diminish the easy swing of the arm.

FIG. 11.

[Illustration: _Bones of the right Forearm._ H, _the humerus;_
R, _the radius; and_ U, _the ulna._]

THE ELBOW.--At the elbow, the humerus articulates with the _ulna_--a
slender bone on the inner side of the forearm--by a hinge joint which
admits of motion in only two directions, _i. e._, backward and
forward. The ulna is small at its lower end; the _radius_, or large
bone of the forearm, on the contrary, is small at its upper end, while it
is large at its lower end, where it forms the wrist joint. At the elbow,
the head of the radius is convex and fits into a shallow cavity in the
ulna, while at the wrist the ulna plays in a similar socket in the radius.
Thus the radius may roll over and even cross the ulna.

THE WRIST, or _carpus_, consists of two rows of very irregular bones,
one of which articulates with the forearm; the other, with the hand. They
are placed side to side, and so firmly fastened as to admit of only a
gliding motion. This gives little play, but great strength, elasticity,
and power of resisting shocks.

THE HAND.--The _metacarpal_ (_meta_, beyond; _karpos_,
wrist), or bones of the palm, support each a thumb or a finger. Each
finger has three bones, while the thumb has only two. The first bone of
the thumb, standing apart from the rest, enjoys a special freedom of
motion, and adds greatly to the usefulness of the hand.

FIG. 12.

[Illustration: _Bones of the Hand and the Wrist._]

The first bone (Figs. 11, 12) of each finger is so attached to the
corresponding metacarpal bone as to move in several directions upon it,
but the other phalanges form hinge joints.

The fingers are named in order: the thumb, the index, the middle, the
ring, and the little finger. Their different lengths cause them to fit the
hollow of the hand when it is closed, and probably enable us more easily
to grasp objects of varying size. If the hand clasps a ball, the tips of
the fingers will be in a straight line.

The hand in its perfection belongs only to man. Its elegance of outline,
delicacy of mold, and beauty of color have made it the study of artists;
while its exquisite mobility and adaptation as a perfect instrument have
led many philosophers to attribute man's superiority even more to the hand
than to the mind. [Footnote: How constantly the hand aids us in explaining
or enforcing a thought! We affirm a fact by placing the hand as if we
would rest it firmly on a body; we deny by a gesture putting the false or
erroneous proposition away from us; we express doubt by holding the hand
suspended, as if hesitating whether to take or reject. When we part from
dear friends, or greet them again after long absence, the hand extends
toward them as if to retain, or to bring them sooner to us. If a recital
or a proposition is revolting, we reject it energetically in gesture as in
thought. In a friendly adieu we wave our good wishes to him who is their
object; but when it expresses enmity, by a brusque movement we sever every
tie. The open hand is carried backward to express fear or horror, as well
as to avoid contact; it goes forward to meet the hand of friendship; it is
raised suppliantly in prayer toward Him from whom we hope for help; it
caresses lovingly the downy cheek of the infant, and rests on its head
invoking the blessing of Heaven,--_Wonders of the Human Body_.]

FIG. 13.

[Illustration: _The Mechanism of the Hip Joint._]

2. THE LOWER LIMBS.--THE HIP--The thigh bone, or _femur_, is the
largest and necessarily the strongest in the skeleton, since at every step
it has to bear the weight of the whole body. It articulates with the hip
bone by a ball-and-socket joint. Unlike the shoulder joint, the cup here
is deep, thus affording less play, but greater strength. It fits so
tightly that the pressure of the air largely aids in keeping the bones in
place. [Footnote: In order to test this, a hole was bored through a hip
bone, so as to admit air into the socket, the thigh bone at once fell out
as far as the ligaments would permit. An experiment was also devised
whereby a suitably prepared hip joint was placed under the receiver of an
air pump. On exhausting the air, the weight of the femur caused it to drop
out of the socket, while the readmission of the air raised it to its
place. Without this arrangement, the adjacent muscles would have been
compelled to bear the additional weight of the thighbone every time it was
raised. Now the pressure of the air rids them of this unnecessary burden,
and hence they are less easily fatigued--WEBER] Indeed, when the muscles
are cut away, great force is required to detach the limbs.

THE KNEE is strengthened by the patella_, or kneepan (_patella_,
little dish), a chestnut-shaped bone firmly fastened over the joint.

The shin bone, or _tibia_, the large, triangular bone on the inner
side of the leg, articulates both with the femur and the foot by hinge
joints. The kneejoint is so made, however, as to admit of a slight rotary
motion when the limb is not extended.

The _fibula_ (_fibula_, a clasp), the small, outside bone of the
leg, is firmly bound at each end to the tibia. (See Fig. 1.) It is
immovable, and, as the tibia bears the principal weight of the body, the
chief use of this second bone seems to be to give more surface to which
the muscles may be attached. [Footnote: A young man in the hospital at
Limoges had lost the middle part of his tibia. The lost bone was not
reproduced, but the fibula, the naturally weak and slender part of the
leg, became thick and strong enough to support the whole body.--STANLEY'S
_Lectures_.]

THE FOOT.--The general arrangement of the foot is strikingly like that of
the hand (Fig. 1). The several parts are the _tarsus_, the
_metatarsus_, and the _phalanges_. The graceful arch of the
foot, and the numerous bones joined by cartilages, give an elasticity to
the step that could never be attained by a single, flat bone. [Footnote:
The foot consists of an arch, the base of which is more extended in front
than behind, and the whole weight of the body is made to fall on this arch
by means of a variety of joints. These joints further enable the foot to
be applied, without inconvenience, to rough and uneven surfaces.--HINTON.]
The toes naturally lie straight forward in the line of the foot. Few
persons in civilized nations, however, have naturally formed feet. The big
toe is crowded upon the others, while crossed toes, nails grown-in,
enormous joints, corns, and bunions abound.

THE CAUSE OF THESE DEFORMITIES is found in the shape and size of
fashionable boots and shoes. The sole ought to be large enough for full
play of motion, the uppers should not crowd the toes, and the heels should
be low, flat, and broad. As it is, there is a constant warfare between
Nature and our shoemakers, [Footnote: When we are measured for boots or
shoes, we should stand on a sheet of paper, and have the shoemaker mark
with a pencil the exact outline of our feet as they bear our whole weight.
When the shoe is made, the sole should exactly cover this outline.] and we
are the victims. The narrow point in front pinches our toes, and compels
them to override one another; the narrow sole compresses the arch; while
the high heel, by throwing all the weight forward on the toes, strains the
ankle, and, by sending the pressure where Nature did not design it to
fall, causes that joint to become enlarged. The body bends forward to meet
the demand of this new motion, and thus loses its uprightness and beauty,
making our gait stiff and ungraceful. (See p. 271.)

DISEASES, ETC.--l. _Rickets_, a disease of early life, is caused by a
lack of mineral matter in the bones, rendering them soft and pliable, so
that they bend under the weight of the body. They thus become permanently
distorted, and of course are weaker than if they were straight, [Footnote:
Just here appears an exceedingly beautiful provision. As soon as the
disproportion of animal matter ceases, a larger supply of mineral is sent
to the weak points, and the bones actually become thicker, denser, harder,
and consequently stronger at the very concave part where the stress of
pressure is greatest.--WATSON'S _Lectures_. We shall often have
occasion to refer to similar wise and providential arrangements whereby
the body is enabled to remedy defects, and to prepare for accidents.]
Rickets is most common among children who have inherited a feeble
constitution and who are ill fed, or who live in damp, ill-ventilated
houses. "Rickety" children should have plenty of fresh air and sunlight,
nourishing food, comfortable clothing, and, in short, the best of hygienic
care.

2. _A Felon_ is a swelling of the finger or thumb, usually of the
last joint. It is marked by an accumulation beneath the periosteum and
next the bone. The physician will merely cut through the periosteum, and
let out the effete matter.

3. _Bowlegs_ are caused by children standing on their feet before the
bones of the lower limbs are strong enough to bear their weight. The
custom of encouraging young children to stand by means of a chair or the
support of the hand, while the bones are yet soft and pliable, is a cruel
one, and liable to produce permanent deformity. Nature will set the child
on its feet when the proper time comes.

4. _Curvature of the Spine_.--When the spine is bent, the packing
between the vertebræ becomes compressed on one side into a wedge-like
shape. After a time, it will lose its elasticity, and the spine will
become distorted. This often occurs in the case of students who bend
forward to bring their eyes nearer their books, instead of lifting their
books nearer their eyes, or who raise their right shoulder above their
left when writing at a desk which is too high. Round shoulders, small,
weak lungs, and, frequently, diseases of the spine are the consequences.
An erect posture in reading or writing conduces not alone to beauty of
form, but also to health of body. We shall learn hereafter that the action
of the muscles bears an important part in preserving the symmetry of the
spine. Muscular strength comes from bodily activity; hence, one of the
best preventives of spinal curvature is daily exercise in the open air.

5. _Sprains_ are produced when the ligaments which bind the bones of
a joint are strained, twisted, or torn from their attachments. They are
quite as serious as a broken bone, and require careful attention lest they
lead to a crippling for life. By premature use a sprained limb may be
permanently impaired. Hence, the joint should be kept quiet, even after
the immediate pain is gone.

6. _A Dislocation_ is the forcible displacement of a bone from its
socket. It is, generally, the result of a fall or a violent blow. The
tissues of the joint are often ruptured, while the contraction of the
muscles prevents the easy return of the bone to its place. A dislocation
should be reduced as soon as possible after the injury, before
inflammation supervenes.

PRACTICAL QUESTIONS.

1. Why does not a fall hurt a child as much as it does a grown person?

2. Should a young child ever be urged to stand or walk?

3. What is meant by "breaking one's neck"?

4. Should chairs or benches have straight backs?

5. Should a child's feet be allowed to dangle from a high seat?

6. Why can we tell whether a fowl is young by pressing on the point of the
breastbone?

7. What is the use of the marrow in the bones?

8. Why is the shoulder so often put out of joint?

9. How can you tie a knot in a bone?

10. Why are high pillows injurious?

11. Is a stooping posture a healthful position?

12. Should a boot have a heel piece?

13. Why should one always sit and walk erect?

14. Why does a young child creep rather than walk?

15. What is the natural direction of the big toe?

16. What is the difference between a sprain and a fracture? A dislocation?

17. Does the general health of the system affect the strength of the
bones?

18. Is living bone sensitive? _Ans_.--Scrape a bone, and its vessels
bleed; cut or bore a bone, and its granulations sprout up; break a bone,
and it will heal; cut a piece away, and more bone will readily be
produced; hurt it in any way, and it inflames; burn it, and it dies. Take
any proof of sensibility but the mere feeling of pain, and it will answer
to the proof.--BELL'S _Anatomy_. Animal sensibility would be
inconvenient; it is therefore not to be found except in diseased bone,
where it sometimes exhibits itself too acutely.--TODD'S _Cyclopedia of
Anatomy_.

19. Is the constitution of bone the same in animals as in man?
_Ans_.--The bones of quadrupeds do not differ much from those of man.
In general they are of a coarser texture, and in some, as in those of the
elephant's head, we find extensive air cells.--TODD'S _Anatomy_.




II.


THE MUSCLES.

"Behold the outward moving frame,
Its living marbles jointed strong
With glistening band and silvery thong,
And link'd to reason's guiding reins
By myriad rings in trembling chains,
Each graven with the threaded zone
Which claims it as the Master's own."

HOLMES.

ANALYSIS OF THE MUSCLES.

_
| 1. The Use of the Muscles.
| 2. Contractility of the Muscles.
_ | 3. Arrangement of the Muscles.
| 1. THE USE, STRUCTURE | 4. The two Kinds of Muscles.
| AND ACTION OF THE | 5. The Structure of the Muscles.
| MUSCLES. | 6. The Tendons for Fastening Muscles.
| | 7. The Muscles and Bones as Levers.
| | 8. The Effect of Big Joints.
| | 9. Action of the Muscles in Walking.
| |_10. Action of the Muscles in Walking.
|
| 2. THE MUSCULAR SENSE.
| _
| 3. HYGIENE OF THE | 1. Necessity of Exercise.
| MUSCLES. | 2. Time for Exercise.
| |_ 3. Kinds of Exercise.
|
| 4. WONDERS OF THE MUSCLES.
| _
| | 1. St. Vitus's Dance.
| | 2. Convulstions.
| | 3. Locked-jaw.
|_5. DISEASES. | 4. Gout.
| 5. Rheumatism.
| 6. Lumbago.
|_ 7. A Ganglion.

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