Framework Of The Body
( Originally Published 1920 )
The Importance of the Bony System.—If you have ever been at the, seashore, you have probably seen jelly-fishes swimming in the water, like clear glassy bells; and you have perhaps noticed some of these same jellyfishes washed up on the sand and looking then like mere lumps of lifeless jelly. They have no bones or hard parts at all, and outside of the water they are quite helpless.
Most animals that live and move about in the air, and many of those that live in the water too, have some sort of skeleton, a system of hard parts which gives their bodies firmness. All the animals which can move quickly and powerfully must have a skeleton, for quick movement requires the shortening of strong muscles, fastened at each end to parts that are firm and rigid.
Sometimes the skeleton of an animal is on the out-side, as in the case of a beetle or an ant; sometimes inside, as in the case of the bones in our own bodies.
What the Bones are Made of.—We often think of the bones as dead things. They are made up, for the most part, of a mineral lime, which is found in limestone, but they have living matter in them too. If bones did not contain living matter, they could not grow; and if you think about it, you will see that, as a child grows, its bones must be growing too. It is important for children to drink plenty of milk, because milk contains a great deal of the lime out of which new bone is made.
The General Plan of the Skeleton.—The general arrangement of the bones in the human body is shown in Fig. 13. You will notice, if you look at this pelvis picture, that in the central part of the body (the trunk) there is a strong backbone, with the ribs attached to it in the upper part, and a pair of flattened bones which make up the pelvis below. The pelvis is a sort of bowl which helps to support the soft organs in the lower part of the trunk.
At the top of the backbone, in the head, is the skull; and down the center of the arms and legs there run rows of bones which branch out into the fingers and toes.
The Bones and the Joints.—There are about two hundred bones in the whole body. They differ very much from one another in shape and size, according to the work they have to do. Some of them are fixed firmly to each other, but at many places the bones are fastened together in such a way that they can be moved in certain directions. Such a place is called a joint. Perhaps you have seen men in the circus who could put their feet up behind their heads and almost tie themselves into bowknots. They show us how the power of bending the joints can be developed by exercise. In very old people, on the other hand, the joints sometimes become so stiff that they can hardly be moved at all. This is one reason why those who are young and strong should be ready to run errands and help old people in every way they can.
There is a great deal of difference between the kind of movements we can make with different joints, de-pending on the ways in which the bones are fitted together. Notice the kinds of movements you can make at your shoulder, your elbow, and your wrist.
The Backbone and the Ribs: The part of the skeleton which keeps the trunk erect is the backbone. It is so important to the body that it has become a symbol of strength of all kinds. We say that a person who is weak and easily influenced has "no backbone," because a person without a backbone could not stand up alone and would be almost as helpless as the jellyfish we were thinking about a little while ago.
The backbone is not a single bone, as you might think from the name, but a row of more than twenty separate bones, each one in the shape of a rather thick ring. These rings are held quite firmly together by bands of muscle, but these muscles "give" so that we can bend the body from side to side and from front to back. Some people can bend the body more easily than others. Stand with your feet together and your knees straight and your arms up over your head; then see if you can swing your arms down and touch the ground in front of you.
The curled, hoop-like ribs form a cage to protect the important organs in the upper part of the trunk. They are joined to the backbone at the back, and to a bone called the breastbone in the front. The ribs are attached to the backbone in such a way that they and the breastbone together can be raised and lowered slightly as we breathe. Breathe deeply and notice how your ribs rise and fall.
The Skull.—It is very important that the brain should be protected from any injury. The bones of the head which form the skull are specially arranged so as to do this; they are not movable like so many of the bones of the body, but are joined firmly together to make a tight case or box. There are openings below for the nerves to come in from the trunk, and openings in front for nerves from the eyes and nose.
The Bones of the Arms and the Legs.—The general arrangement of the larger bones in the arms and the legs is shown in Fig. 14. Notice that arms and legs are built very much on the same plan, the part above the elbow or knee being strengthened by a single large bone, the part below by two bones side by side. Five rows of smaller bones run out through the palm of the hand and the upper part of the foot, into fingers and toes.
Holding the Body Well: We all have the same kind of framework in our bodies; but you would hardly think so to look at the people you meet in the street, or perhaps even at the children in your schoolroom. Some are erect and strong and well-balanced on their feet so that it is a delight to look at them, while others are stoop-shouldered and slouching, with bent back and head run forward. The bones are the same in each case. It is only that one person has trained his muscles to hold the bones in place, while the other has let the muscles grow slack and loose and has become as much like the jellyfish as he possibly could.
If you hold your body correctly, a line dropped from the front of the ear should fall within the front half of the foot when you are standing still. The shoulders should be flattened, the head up, the knees straight, the feet set squarely side by side and pointing straight forward. When practicing a good position, try to "stand tall." In sitting, the body should be bent only at knees and waist, the head, neck, and trunk being in one straight line.
The habit of holding the body properly is important, not only for the general appearance of the body, but for health and strength as well. In a stooping, slouching body, the inner parts are crowded together and injured so that they cannot do their work well. Boys and girls who have the habits of clasping their hands behind their backs, folding their arms tightly in front, or placing the hands on the hips with the thumbs forward are very likely to be round-shouldered and flat-chested.
Things that Prevent Us from Holding the Body Well. Sometimes a bent or deformed body is the result of bad habits of sitting, formed perhaps in school. See if the desk and seat at school are so arranged that you can sit comfortably at your work with your back straight. If not, ask the teacher if your seat cannot be changed or the chair raised or lowered. If your chair is too high or too near your desk, so that you have to bend your shoulders over or twist your body sideways to get at your work, it may do you real harm.
Tight clothing also is bad for the body. Shoes that are too tight, and shoes that have high heels, injure the foot itself and interfere with the proper carriage of the body as a whole. It was once the rule in China to bind up the feet of girl babies tightly so that they could not grow, and it is very sad to see the women walking unsteadily, on feet so small and misshapen they hardly look like feet at all. The Chinese of to-day have for the most part given up this horrible custom, and we ought to be as sensible as they and wear shoes that are big enough to let our feet develop properly.
The Story of the Young Prince and the Robber Children.—A story is told of a young prince who was once traveling with some of his courtiers to a distant city. The party was set upon in the forest by robbers, who killed all the attendants and carried off the prince as a prisoner. They took off his fine clothing and made him pile wood and carry water and do the rest of the work of the camp, just as their own children did.
The governor of the city heard from people in the forest about the kidnapping, and he sent out soldiers, who drove off the robbers and brought all the children in the camp to the governor's palace. The young prince told the soldiers who he was and thanked them for rescuing him. The robbers' children, however, were as bad as their parents. As soon as the real prince had spoken, one of them cried out, "That is not true. He is not the prince. I am the prince." And another said, "No, I am the prince;" and another, and another.
Prince and all were dirty and clothed in rags. No, one in this city had seen the prince since he was a baby, and the soldiers were much puzzled to know what to do.
The governor of the city, however, was an old man and very wise. He had all the would-be princes brought before him. After looking at them all fora moment, he went up to the real prince and said, "Your Highness, I know that you are the prince because you hold your-self like a king; and I know that these others are the children of the robbers because they slouch and crouch like thieves, as they are."
If you were kidnapped, as the prince was, could any one tell you from one of the robber children by the way you hold yourself?