Showing A thickening of flexors on front of arm, as forearm is swung forward, and B thickening of extensors on back of arm, as forearm is swung backward.
The muscles of the limbs are almost as numerous as those of the trunk of the body, and even more complex. Most of them, on both arms and legs, are in two great groups—one known as the "benders," or flexors, which, when they shorten, bend the limb; and the other, the "straighteners," or extensors, which straighten or extend it.
On the front of the arm, for instance, we have the large biceps ("two-headed") muscle, which runs from the shoulder to the bone of the forearm just below the elbow and, when it shortens, bends the elbow and lifts the arm toward the body.
On the back of the upper arm is the triceps ("three-headed") muscle, which is fastened at its lower end to a big spur of bone, the "point" of the elbow; when it shortens, acting lever fashion, it straightens or extends the arm. If this is done quickly, the fist is swung outward with force enough to strike quite a sharp blow, though, as you know, if you wish to hit really hard, you have to strike with the weight and muscles of the full arm and the body behind it, or, as we say, "from the shoulder."
Showing A thickening of flexors on front of thigh and leg, as foot is swung forward; and B thickening of extensors on back of thigh and leg, as leg is swung backward.
P, patella (knee cap); M, muscle; L, ligament; T, tendon.
In the lower limbs, the muscles are larger because they have heavier work to do, supporting and moving the whole weight of the body; but they are simpler in their arrangement since they have not such a variety of movements to carry out. The principal muscle in the thigh is the great muscle running down the front of the thigh, and fastening to the upper border of the patella, or knee cap. This muscle, when it shortens, straightens or extends the limb, or lifts the foot from the ground and swings it forward as in walking, or raises the knee up toward the body when we are sitting or lying down. You can easily tell how much it is used in walking by remembering how stiff and sore it gets when you have taken an unusually long tramp, particularly if there has been much hill-climbing in it. On the back of the thigh, runs another great group of muscles, which bend or flex the limb when they shorten. When the knee is bent, you can feel their tendons, or sinews, stand out as hard cords beneath the knee; hence, this group is called the ham-string muscles.[23]
How the Muscles are Fed. Our muscles are not only the largest, but the "livest" part of our bodies. Their contractions and movements are caused by their tiny "explosions" (like the chugging of an automobile, except that we can't hear them); and in this way they burn up the largest part of the food-fuel which we eat—mostly in the form of sugar. When they have burned up their surplus food-fuel, they call for more; and when this demand has been telegraphed to the brain, we say we are hungry, and that exercise has given us an appetite. While the muscles are at work, they demand that large supplies of fresh fuel shall be brought to them through the blood vessels; and this makes the heart beat harder and faster, and improves the circulation. As they burn up this fuel, they form smoke and ashes, or waste materials, which must be got rid of—the fluid part by perspiration from the surface of the skin, and through the kidneys, and the gas, or "smoke," through the lungs. This is the reason why, during exercise, we breathe faster and deeper than at other times, and why our skin begins first to glow and then to perspire.
If these waste-materials form in the muscles faster than the blood can wash them out, they poison the muscle-cells and we begin to feel tired, or fatigued. This is why our muscle-cells are often so stiff and sore next morning after a long tramp, or a hard day's work, or a football game. A hot bath or a good rub-down takes the soreness out of the muscles by helping them to get these poisonous wastes out of their cells.
Thus when we play or run or work, we are not only exercising our muscles and making them gain strength and skill, but we are stirring up, or stimulating, almost every part of our body to more vigorous and healthful action.
Indeed, as our muscles alone, of all our body stuffs, are under the control of the will, our only means of deliberately improving our appetites, or strengthening our hearts or circulation, or invigorating our lungs, or causing a large part of our brains and minds to grow and develop, is through muscular exercise. This is why nature has taken care to make us all so exceedingly fond of play, games, and sports of all sorts, in the open air, when we are young; and, as we grow older, to enjoy working hard and fighting and "hustling," as we say; and that is the reason, also, why we are now making muscular exercise such an important part of education.
CHAPTER XIX
THE STIFFENING RODS OF THE BODY-MACHINE
What Bones Are. The bones are not the solid foundation and framework upon which the body is built, as they are usually described. They are simply a framework of rods and plates which "petrified," or turned into spongy limestone after the body was built, to make it firmer and stiffen it for movement. All the animals below the fishes, such as worms, sea-anemones, oysters, clams, and insects, get along very well without any bones at all; and when we are born, our bones, which haven't fully "set" yet, are still gristly and soft. The cores of the limbs, as they begin to stiffen, first turn into gristle, or cartilage, and later into bone; indeed, many of our bones remain gristle in parts until we are fifteen or sixteen years of age. This is why children's bones, being softer and more flexible than those of grown-up people, are not so liable to break or snap across when they fall or tumble about; and why, too, they are more easily warped or bent out of shape through lack of proper muscular exercise and proper food.
Bones are strips of soft body-stuff soaked with lime and hardened, like bricklayer's mortar, or concrete.[24] When you know the shape of the body, you know the bones; for they simply form a shell over the head and run like cores, or piths, down the centre of the back, and down each joint of the limbs.
In turning into spongy limestone, or animal concrete, they have become one of the deadest tissues in the body. They are tools of the muscles, the levers by which the muscles move the limbs and body about; they never do anything of their own accord. On account of their lifelessness and lack of vitality, they are rather easily attacked by disease, or broken by a blow or fall. There are such a large number of bones (two hundred and six, all told), and they resist decay and last so much longer after death than any other parts of the body, that they fill our museums and text-books of anatomy, form most of our fossils, and have thus given us rather an exaggerated idea of their importance during life.
The Frame-Work of the Body. Just look at any part of the body and imagine that it has a bony core of about the same general shape as itself, and you can reason out all the bones of the skeleton. To begin at the top, the skull is a box of strong, plate-like bones, which have hardened to protect the brain as it grew; and the shape of its upper, or brain, part is exactly that of the head, as you can easily feel by laying your hands upon it. Then come bony shells, or sockets, for the eyes and nose; and, below these, two heavy half-circles of bone, like the jaws of a steel trap, to carry the teeth.
V, vertebra; C, cartilage protecting spinal cord; A, point of articulation on the right side.
The thickness of the lower jaw and the size and squareness of the angle where it bends upward to be hinged to the skull, below the ear, are what give the appearance of squareness and determination to the faces of strong, vigorous men or women. If we want to imply that a person has a feeble will, or weak character, we say he has a "weak jaw."
The skull rests upon the top of the backbone, or spinal column, which, instead of being one long solid bone, is made up of a number of pieces, or sections, known as vertebræ. Each one of these vertebræ has a ring, or arch, upon its back. These, running one after the other, form a jointed, bony tube to protect the spinal cord, or main nerve-cable of the body, which runs through it.
Although the backbone can bend forward or backward, or twist from side to side a little, by the little pieces of bone of which it is built up gliding and turning upon one another, it is really very stiff and rigid, so as to protect the spinal cord and prevent its being stretched or pinched. Most of the movements which we call bending the spine are really movements of other joints which connect the body or head with it. When we bend our necks, for instance, we hardly bend the backbone at all, as most of the movement is made in the joint at the top of it, between it and the skull. Similarly, when we bend our backs, we really bend our backbones very little; for most of the movement comes at the hip joints, between the thighs and the hip bones.
Each of the limbs has a single, long, rounded bone in the upper part, known in the arm as the humerus, and two bones in the lower part. These last are known as the radius and ulna (the "funny bone") in the forearm, and the tibia and fibula in the leg. The shoulder-joint is made by the rounded head of the humerus fitting into the shallow cup of the scapula, or shoulder-blade. It is shallower than the hip joint to allow it freer movement; but this makes it weaker and much more easily dislocated, or put out of joint,—the most so, in fact, of any joint in the body.
|
A BALL-AND-SOCKET JOINT
Hip joint. |
A HINGE JOINT
Knee joint, with the knee cap removed |
The hip joints are deep, strong, cup-shaped sockets upon each side of the hip bones, or pelvis, into which fit the heads of the femurs or thigh bones. When the hip joint does become dislocated, it is very hard to put back again, on account of its depth and the heavy muscles surrounding it. It is quite subject to the attack of tuberculosis, or "hip-joint disease."
The joints, or points at which the bones join one another, look rather complicated, but they are really as simple as the bones themselves. Each joint has practically made itself by the two bones' rubbing against each other, until finally their ends became moulded to each other, and formed the ball-and-socket, or the hinge, according to whichever the movements of the "bend" required. The ends, or heads, of the bones which form a joint are covered with a smooth, shining coating of cartilage, or gristle, so that they glide easily over each other.
Around each joint has grown up a strong sheath of tough, fibrous tissue to hold the bones together; and, inside this, between the heads of the bones, is a very delicate little bag, or pouch, containing a few drops of smooth, slippery fluid (synovial fluid) to lubricate the movements of the joint. This is sometimes called the "joint oil," though it is not really oil.
Bones are covered with a tough skin, or membrane (periosteum). They are hardest and most solid on their surfaces, and hollow, or spongy, inside. The long bones of the limbs are hollow, and the cavity is filled with a delicate fat called marrow—just as an elderberry stem or willow-twig is filled with pith. This tubular shape makes them as strong as if they were solid, and much lighter.[25]
The short, square, and flattened bones of the body, such as those of the wrist, the skull, and the hips, instead of being hollow inside are spongy; and the spaces in the bone-sponge are filled with a soft tissue called the red marrow in which new red and white corpuscles for the blood are born, to take the place of those which die and go to pieces.
CHAPTER XX
OUR TELEPHONE EXCHANGE AND ITS CABLES
The Brain. We are exceedingly proud of our brain and inclined to regard it as the most important part of our body. So it is, in a sense; for it is the part which, through its connecting wires, called the nerves, ties together all the widely separated organs and regions in our body, and helps them to work in harmony with one another. We speak of it as the master and controller of the body; but this is only partially true.
The brain is not so much the President of our Cell Republic as a great central telephone exchange, where messages from all over the body are received, sifted, and transmitted in more or less modified form, to other parts of the body. Three-fourths of the work of the brain consists in acting as "middle-man," or transmitter, of messages from one part of the body to another. In fact, the brain is far more the servant of the body than its ruler; and depends for its food supply, its protection, its health, and its very life, upon the rest of the body. The best way to keep the brain clear and vigorous is to keep the muscles of the stomach, the liver, the heart, and the entire body in good health.
What the Brain Does. The brain is the very wonderful organ with which we do what we are pleased to call our thinking, and also a number of other more important things of which we are not conscious at all. It is a large organ, weighing nearly three pounds when full grown. In shape it is like an oval loaf of bread split lengthwise by a great groove down the centre, and with a curiously wrinkled or folded surface. The two halves of the brain, called hemispheres (though more nearly the shape of a coffee-bean), are alike; and each one, by some curious twist, or freak, of nature, receives messages from, and controls, the opposite half of the body—the right half controlling the left side of the body, while the left half controls the right side of the body. Thus an injury or a hemorrhage on the left side of the brain will produce paralysis of the right side, which is the side on which a stroke of paralysis most commonly occurs.
All the nerve fibres in each half or hemisphere of the upper brain run downward and inward like the sticks of a fan, to meet in a strap-like band, or stalk, which connects it with the base of the brain and the spinal cord. A very small amount of damage at this central part, or base, of the brain will produce a very large amount of paralysis. We may have large pieces of the bones of the skull driven into the outer surface of the brain, or considerable masses of our upper brain removed, or destroyed by tumors or disease, without very serious injury. But any disease or injury which falls upon the base of the brain, where these stalks run and big nerve-knots (ganglia) lie, will cause very serious damage, and often death.
The whole upper brain is a department of superintendence, which has grown up from the lower brain to receive messages, compare them with each other, and with the records of previous messages which it has stored up, thus giving us the powers which we call memory, judgment, and thought. Unfortunately, however, long and carefully as we have studied the brain, we really know little about the way in which it carries out these most important processes of memory, of judgment, and of thought, or even of the particular parts of it in which each of these is carried out.
No part of the brain, for instance, seems to be specially devoted to, or concerned in, memory or reason or imagination, still less to any of the emotions, such as anger, joy, jealousy or fear; so all those systems which pretend to tell anything about our mental powers and our dispositions by feeling the shapes of our heads, or the bumps on them, are pure nonsense.
The most important and highest part of the brain is its surface, a thin layer of gray nerve-stuff, often spoken of as the gray matter (the cortex, or "bark"), which is thrown into curious folds, or wrinkles, called convolutions. This gray matter is found in the parts of the nervous system where the most important and delicate work is done. The rest of the nervous system is made up of what is called white matter, from its lighter color; and this is chiefly mere bundles of telephone wires carrying messages from one piece of gray matter to another, or to the muscles.
We also know that a certain rather small strip of the upper brain-surface, or cortex, about the size of two fingers, running upward and backward from just above the ear, controls the movements of the different parts of the body. One little patch of it for the hand, another for the wrist, another for the arm, another for the shoulder, another for the foot, and so on. We can even pick out the little patch which controls so small a part of the body as the thumb or the eyelids. So when we have a tumor of the brain or an injury to the skull in this region, we can tell, by noticing what groups of muscles are paralyzed, almost exactly where that injury or tumor is. Then we can drill a hole in the skull directly over it and remove the tumor, lift up the splinter of bone, or tie the ruptured blood vessel.
Three other patches, or areas, running along the side of the brain, each of them about two inches across, are known to be the centres for smell, hearing, and sight, that for sight lying furthest back. Damage to one of these areas will make the individual more or less completely blind, or deaf, or deprived of the sense of smell, as the case may be.
At the lower part of the area which controls the muscles of the different parts of the body, above and a little in front of the tip of the ear, lies a very important centre, which controls the movements of the tongue and lips, and is known as the speech centre. If this should be injured or destroyed, the power of speech is entirely lost. This, curiously enough, lies upon the left side of the brain, and is the only one-sided centre in the body. Why this is so is somewhat puzzling, except that as speech is made up both of sound and of gesture, and our gestures are usually made with the right hand, it is not unreasonable to suppose that the speech centre should have grown up on that side of the brain which controls the right hand, which is, as you remember, the left hemisphere. What makes this more probable is that in persons who are "left-handed," the speech centre lies upon the opposite or right side of the brain. So it is waste of time and does more harm than good to try to "break" any child of left-handedness.
The Spinal Cord. Running downward from the base of the brain, like the stalk of a flower, is a great bundle of nerve-fibres, the central cable of our body telephone system, the spinal cord. This, you will remember, runs through a bony tube formed by the arches of the successive vertebrae; and as it runs down the body, like every other cable it gives off and receives branches connecting it with the different parts of the body through which it passes. These branches are given off in pairs, and run out through openings between the little sections of bone, or vertebrae, of which the spinal column is made up. They are called the spinal nerves, and each pair supplies the part of the body which lies near the place where it comes out of the cord.
The spinal nerves contain nerve wires of two sorts—the inward, or sensory, and the outward, or motor, nerves. The sensory, or ingoing, nerves come from the muscles and the skin and bring messages of heat and cold, of touch and pressure, of pain and comfort, to the spinal cord and brain. The outward, or motor, nerves running in the same bundle go to the muscles and end in curious little plates on the surface of the tiny muscle fibres, and carry messages from the spinal cord and brain, telling the muscles when and how to contract.
As the spinal cord runs down the body, it becomes gradually smaller, as more and more branches are given off, until finally, just below the small of the back and opposite the hip bones, it breaks up by dividing into a number of large branches which go to supply the hips and lower limbs.
While most of the spinal cord is made up of bundles of white fibres, carrying messages from the body to the brain, its central portion, or core, is made of gray matter. The reason for this is that many of the simpler messages from the surface of the body and the movements that they require are attended to by this gray matter, or ganglia, of the spinal cord without troubling the brain at all.
For instance, if you were sound asleep, and somebody were to tickle the sole of your bare foot very gently, the nerves of the skin would carry the message to the gray matter of the spinal cord, and it would promptly order the muscles of the leg to contract, and your foot would be drawn away from the tickling finger, without your brain taking any part in the matter, though, if you had been awake, you would of course have known what was going on.
This sort of reply to a stimulus, or "stirring up," without our knowing anything about it, is known as a reflex movement. Not only are many of these reflexes carried out without any help from the will, or brain, but they are so prompt and powerful that the brain, or will, can hardly stop them if it tries, as, for instance, in the case of tickling the feet. You can, if you make up your mind to it, prevent yourself from either wriggling, pulling your foot away, or giggling, when the sole of your foot is tickled; but if you happen to be at all "ticklish," it will take all the determination you have to do it, and some children are utterly unable to resist this impulse to squirm when tickled.
This extraordinary power of your reflexes has developed because only the promptest possible response, by jerking your hand away or jumping, will be quick enough to save your life in some accidents or emergencies, when it would take entirely too long to telephone up to the brain and get its decision before jumping. When you are badly frightened, you often jump first and discover that you are frightened afterwards; and this jump, under certain circumstances, may save your life. On the other hand, like all instinctive or impulsive movements, it may get you into more trouble than if you had kept still.
As you will see by the picture, the spinal nerves, which are given off from the cord in the lower part of the neck and between the shoulder blades, are gathered together into a great loose bundle to form the long nerve-wires needed to supply the shoulders and arms. Those given off from the small of the back just above the hips also run together to form, first a network and then a big single nerve-cord, called the sciatic nerve, which many of you have probably heard of from the frightfully painful disease due to an inflammation of it, called sciatica. It is the largest nerve-cord in the body, running down the middle of the back of the thigh to supply the muscles of two-thirds of the leg.[26]
The substance of both the spinal cord and the brain is made up of millions of delicate, tiny cells, called neurons, most of which, with very long branches, are arranged in chains for carrying messages, forming the white matter; while the others lie in groups, or ganglia, for sorting and deciding upon messages, forming the gray matter.
Just at the top of the spinal cord, where it passes into the skull and joins with the brain, it swells out into a sort of knob, about the size of a queen olive or the head of a gold-headed cane, which is known as the medulla, or "pith." This is the most vital single part of the entire brain and nervous system; and the smallest direct injury to it will produce instant death, partly because all the messages which pass between the brain and the body have to go through it, and partly because in it are situated the centres which control breathing and the beat of the heart, and another quite important but less vital centre,—that for swallowing.
How Messages are Received and Sent. Now to learn how smoothly and beautifully this nerve telephone system of ours works, and how simple it really is, although it has such a large number of lines and so many telephones on each line, and such a large central exchange, let us see how it deals with a message from the outside world. Suppose you are running barefoot and step on a thorn. Instantly the tiny nerve bulbs in the skin of the sole of your foot are stimulated, or set in vibration, and they send these vibrations up the sciatic nerve, into and up the whole length of the spinal cord, through the medulla, which switches them over to the other side of the brain up through the brain stalk, and out to the part of the surface (cortex) of the brain which controls the movements of the foot. All this takes only a fraction of a second, but it is not until the message reaches the brain-surface that you feel pain. If you were to cut the sciatic nerve, or even tie a string tightly around it, you could prick or burn the sole of your foot as much as you pleased, and you would not feel any pain at all.
As soon as the surface of the brain has recognized the pain and where it comes from, it promptly sends a return message back down the same cable, though by different nerve-wires, to the muscles of the foot and leg, saying, "Jerk that foot away!" As a matter of fact, this message will arrive too late, for the centres in the spinal cord will already have attended to this part of the matter, often almost before you know that you are hurt.
However, there is plenty of other work for the brain to do; and its next step, quicker than you can think, is to wake up a dozen muscles all over the body with the order, "Sit down!" And you promptly sit down. At the same time, the brain "central" has ordered the muscles of your arms and hands to reach down and pick up the foot, partly to protect it from any further scratch, and partly to pull the thorn out of it. Next it rushes a hurry call to the muscles controlling your lungs and throat, and says, "Howl!" and you howl accordingly. Another jab at the switchboard, and the eyes are called up and ordered to weep, while at the same time the muscles of the trunk of your body are set in rhythmic movement by another message, and you rock yourself backward and forward.
This weeping and rocking yourself backward and forward and nursing your foot seem rather foolish,—indeed you have perhaps often been told that they are both foolish and babyish,—but, as you say, you "can't help it," and there is a good reason for it. The howl is a call for help; and if the hurt were due to the bite of a wolf or a bear, or the cut had gone deep enough to open an artery, this dreadfully unmusical noise might be the means of saving your life; while the rocking backward and forward and jerking yourself about would also send a message that you needed help, supposing you were so badly hurt that you couldn't call out, to anyone who happened to be within sight of you. So that it isn't entirely babyish and foolish to howl and squirm about when you are hurt—though it is manly to keep both within reasonable limits.
If the message about the thorn had been brought by your eyes,—in other words, if you had seen it before you stepped on it,—then a similar but much simpler and less painful reflex would have been carried out. The image of the thorn would fall on the retina of the eye and through its optic nerve the message would be flashed to the brain: "There is something slim and sharp in the path,—looks like a thorn." When this message reached the brain, and not till then, would you see the thorn, just as in the case of the pain message from the foot. Then the brain would take charge of the situation just as before, flashing a hasty message to the muscles of the legs, saying, "Jump!" while its message to the throat and lungs, instead of "Yell," would be merely, "Say, 'Goodness!' or 'Whew!'" and you would say it and run on.
If the thing in the grass, instead of a thorn, happened to be a snake, and you heard it rustle, then the warning message would come through your ears to the brain, and you would jump just the same; though, as it is not so easy to tell by a hearing message exactly where the sound is coming from, you might possibly jump in the wrong direction and land on top of the danger.
This is the way in which you see, hear, and form ideas of things. Your eye telegraphs to the brain the colors; your ear, the sounds; and your nose, the smells of the particular object; and then your brain puts these all together and compares them with its records of things that it has seen before, which looked, or sounded, or smelt like that, and decides what it is; and you say you see an apple, or you hear a rooster crow, or you smell pies baking. Remember that, strange as it may seem, you don't see an orange, for instance, but only a circular patch of yellowness, which, when you had seen it before, and felt of it with your hand, you found to be associated with a feeling of roundness and solidness; and when you lifted it toward your nose, with the well-known smell of orange-peel; so you called it an orange. If the yellow patch were hard, instead of elastic, to the touch, and didn't have any aromatic smell when you brought it up to your nose, you would probably say it was a gourd, or an apple, or perhaps a yellow croquet ball. This is the way in which, we say, our senses may "deceive" us, and is one of the reasons why three different people who have seen something happen will often differ so much in their accounts of it.
It is not so much that our senses deceive us, but that we draw the wrong conclusions from the sights, sounds, and smells that they report to our brains, usually from being in too great a hurry and not looking carefully enough, or not waiting to check up what we see by touching, hearing, or tasting the thing that we look at.
This message-and-answer system runs all through our body. For instance, if we run fast, then the muscle cells in our legs burn up a good deal of sugar-fuel, and throw the waste gas, or smoke, into the blood. This is pumped by the heart all over the body, in a few seconds. When this carbon dioxid reaches the breathing centre in the medulla, it stirs it up to send promptly a message to the lungs to breathe faster and deeper, while, at the same time, it calls upon the circulation centre close to it, to stir up the heart and make it beat harder and faster, so as to give the muscles more blood to work with. If some poisonous or very irritating food is swallowed, as soon as it begins to hurt the cells lining the stomach, these promptly telegraph to the vomiting centre in the brain, we begin to feel "sick at the stomach," the brain sends the necessary directions to the great muscles of the abdomen and the diaphragm, they squeeze down upon the stomach, and its contents are promptly pumped back up the gullet and out through the mouth, thus throwing up the poisons.
And so on all over the body—every tiniest region or organ in the body, every square inch of the skin, has its special wire connecting it with the great telephone exchange, enabling it to report danger, and to call for help or assistance the moment it needs it.
CHAPTER XXI
THE HYGIENE OF BONES, NERVES, AND MUSCLES
HOW TO GET AND KEEP A GOOD FIGURE
Erect Position is the Result of Vigorous Health. Naturally and properly, an erect, graceful figure and a good carriage have always been keenly desired; and much attention has been paid to the best means of acquiring them; as we say, we try to "get the habit" of carrying ourselves straight and well. But it must be remembered that an erect figure and a good carriage are the results of health and vigor, rather than the cause of them.
Stooping, round shoulders, sitting "all hunched up," or a shuffling gait, are owing partly to bad habits, or "slouchiness," but chiefly to weak muscles and a badly-fed nervous system, often due to a poor digestion and a weak circulation. If a child is not healthy and vigorous, then no amount of drilling or reminders to "sit straight" and "stand erect" will make him do so.
It is of great importance that the child should take an erect and correct position for reading and writing, and while sitting at his desk; and that the desk and the seat should fit him. But it is more important that he should not sit at his desk in a stuffy room long enough to be harmed by a cramped position.
There are few children who will "hump over" at their desks, if the muscles of their backs and necks are strong and vigorous, and their brains well ventilated. Nor will many of them bore their noses into their books, or sprawl all over their copy books when they write, unless the light is poor, or they have some defect of the eyes which has not been corrected by proper glasses. A bad position or a bad carriage in a child is a sign of ill health, and should be treated by the removal of its cause.
Curvatures—Their Cause and Cure. There are various forms of curvatures, or bendings, of the spine which are supposed to be owing to faulty positions of sitting or of carrying the body. There is wide difference of opinions as to their cause; but this all are agreed on, that they practically never occur in sturdy, well-grown, active children; and the way that they are now corrected is by careful systems of balancing, muscular exercise, open-air life, and abundant feeding, instead of using steel braces, or jackets, or schoolroom drills.
Note the pupil in the second row who evidently needs eye glasses.
Much the same is true of other deformities and defects of the body, as, for instance, round shoulders, or "flat-foot," or even such serious ones as "club-foot" and "bow-legs." Nearly all these are caused by the weakness or wrong action of some muscle, or groups of muscles. If this be long continued or neglected, the bones—which, you will remember, were made by the muscles in the first place—will be warped out of shape. When this has occurred, it is often necessary to bring back the limb, or foot, into a nearly straight position by mechanical or surgical means; but we now largely depend upon muscular exercises combined with rubbing and massage with the hand, and on building up the general vigor of the entire body, so that the muscles will pull the limb or the backbone back into proper position. Take care of the muscles, and the bones will take care of themselves! Make the body strong, vigorous, and happy, and it will "hold" and "carry" itself.
The absence of impression on the inner border of the normal footprint at A is due to the elevation of the foot by the longitudinal arch. The other arch lies across the foot in front of this.—After Schmidt.
OUR FEET
The Living Arches of the Foot. One of the most important things to look after, if we wish to have an erect carriage and a swift, graceful gait, is the shape and vigor of the feet. Each foot consists of two springy, living arches of bone and sinew, which are also used as levers, one running lengthwise from the heel to the ball of the toes, and the other crosswise at the instep. These arches are built largely of bones, but are given that springy, elastic curve on which their health and comfort depend, and are kept in proper shape and position, solely by the action of muscles—those of the lower part of the leg and calf.
The purpose of these arches is to "give," or spring, like carriage springs, and thus break the shock of each step and cause the body to "ride" easily and comfortably. In order that a spring may "give," it must expand, or spread. Far the commonest and most serious cause of a poor, easily tired gait and a bad carriage is tight shoes, which, by being too short, or too narrow, or both, prevent the arches of the foot from "giving" and expanding. Not only does this produce corns, bunions, and lame feet, but it makes both standing and walking painful and feeble, and destroys the balance of the entire body, causing the back to ache, the shoulders to droop forward, and the neck muscles to tire themselves out trying to pull the head back so as to keep the face and eyes erect. Thus one soon tires, and never really enjoys walking. If this disturbance of balance is increased by high heels, thrust forward under the middle of the foot, the result is very bad.
(1) A foot that has never worn a shoe (from a photograph); (2) A foot so cramped and bent as to prevent firmness of step and gait.
Our Shoes, an Important Factor in Health. Few more ingenious instruments of crippling and torture have ever been invented than fashionable tight shoes with high heels.
Kipling never said a shrewder or truer thing than when he made Mulvaney, the old Irish drill-sergeant, tell the new recruit, "Remimber, me son, a soljer on the marrch is no betther than his feet!" and this applies largely to the march of life as well.
Every shoe should be at least three-quarters of an inch longer, and from half to three-quarters of an inch wider, than the foot at rest, to allow proper expansion of these great "carriage-spring" arches. If children run free in the open air, either barefoot, or with light, loose, well-ventilated shoes, or sandals, they will have little trouble, not only with bunions, corns, "flat-foot," or lameness, but also with their backs, their gait, and their carriage. Easily half of our backaches, and inability to walk far or run fast in later life, to say nothing of over-fatness and dyspepsia, are caused by tight shoes.
SLEEP AND REST
Why We Need Rest. A most important element in a life of healthful exercise, study, and play is rest. Even when we are hard at work, we need frequent breathing spells and changes of occupation and amusement to keep one part of our muscles, or our brains, from poisoning itself. But after a time, in even the strongest and toughest of us, there comes a period when no change of occupation, no mere sitting still, will rest us; we begin to feel drowsy and want to go to sleep. This means partly that the fatigue poisons, in spite of fresh air and change, have piled up faster than we can burn them, so that we need sleep to restore the body.
All day long we are making more carbon dioxid than the oxygen we breathe in can take care of; while we sleep, the situation is reversed—the oxygen is gaining on the carbon dioxid. This is why the air in our bedrooms ought to be kept especially pure and fresh.
But the need goes deeper than this: sleeping and waking are simply parts of the great rhythm in which all life beats—a period of work followed by a period of rest. Continuous, never-ceasing activity for any living thing quickly means death. While externally the body appears to be at rest, the processes of growth and upbuilding probably go on more rapidly when we are asleep than when we are awake. The benefits of exercise are made permanent and built into the body during the sleep that follows it. The more rapidly young animals are growing, the more hours out of the twenty-four they spend in sleep. When you sleep, you are not stopping all the useful activities of your body and mind, you are simply giving some of the most useful and most important of them a chance to work. The only likeness between sleep and death is that in both the body is quiet and the eyes are closed. Really we are never more alive and growing than when asleep.
It is of the utmost importance that young children especially have all the sleep they need, and that is precisely all that they can be induced to take. The best rule for you, then, to follow, is to go to bed when you feel sleepy, and to get up when you wake rested. Every child under twelve should have at least ten hours of sleep, and every grown person eight, or better still, nine hours. Time spent in sound, refreshing sleep, is time well spent. If you cannot sleep well, it is a signal that something is wrong with your health, or your habits—a danger signal of great importance, which should be attended to at once. The best and only safe sleep-producer is exercise in the open air.
DISORDERS OF MUSCLES AND BONES
The Muscles and Bones Have Few Diseases. Considering how complex it is, and the never-ceasing strain upon it, this moving apparatus of ours, the nerve-bone-muscle-machine, is surprisingly free from disease. The muscles, though they form nearly half our bulk, have scarcely a single disease peculiar to them, or chiefly beginning in them, unless fatigue and its consequences might be so regarded. They may become weakened and wasted by either lack or excess of exercise, by under-feeding, or by loss of sleep; but most of their disturbances are due to poisons which have got into the blood pumped through them, or to paralysis or other injuries to the nerves that supply them.
The muscles of an arm, for instance, which has been lashed to a splint, or shut tightly in a cast for a long time, waste away and shrink until the arm becomes, as we say, "just skin and bone"; and the same thing will happen if the nerve supplying a muscle, or a limb, is cut or paralyzed.