Читать книгу The House We Live In; or, The Making of the Body онлайн

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We will begin with the bones of the head. They form what is called the skull. It is made of a number of bones, joined like two saws with the teeth hooked together. The “chin bone,” or jaw bone, is one of the bones of the head.

Skull.

Let me show you a picture of one of the most wonderful bones of the body. It is called the spine, or spinal column. Perhaps you can feel some little knobs or ridges in your back. The back-bone is made of twenty-four little bones piled one on top of another. Suppose you had twenty-four spools or reels of cotton, and you should run a string through them. When you hold them upright, you see you can bend them any way you wish, or keep them straight. Now if each spool had three wings like the one in the picture, they would be shaped very much like the bones that form the spine. The string is like the marrow, or “spinal cord,” which passes through the spinal column from top to bottom. The bones which make up the lower part of the spine are much larger than those at the top. Little soft cushions are placed between all these bones, something like India-rubber. These cushions are to keep the body and brain from being jarred, just as the springs in our carriage help you to ride easily. They also help us to bend the body backward or forward as we choose. You see if the spine was one long straight bone we could not bend at all. If we keep bending over while walking or working, after a time the cushions will get used to that position and we shall have a bad figure.