Читать книгу The House We Live In; or, The Making of the Body - Vesta J. Farnsworth - Страница 6

Table of Contents

OUR FRAME

OTHER: Every building must have a foundation and a frame of some kind to make it strong and give it shape. It is the same with the house we call our body. The frames of houses which men build are made of wood or iron; but the framework of the body is built of bones. Perhaps you have noticed that in the frames of buildings some pieces of timber are short, and some are long, and they are cut into many different shapes and sizes. So it is with the bones of the body. How many do you think it takes to make our frame?

Helen: About fifty.

Percy: I guess one hundred.

Mother: Not quite right, for there are over two hundred. All the bones together are called the skeleton. The frame of a house divides it into rooms, and on it are fastened the boards, laths, and shingles. In the house in which we live the flesh is fastened to the bones, and the whole is covered with skin. This framework also protects the curious rooms inside the trunk of the body. The largest bone in our frame is the leg bone, which reaches from the hip to the knee. It is called the femur, or thigh bone.

Elmer: Are the bones solid, mother?

The thigh bone.

Mother: No; I have brought some pictures to show you how they look, for we can not see our own bones. One of them shows a bone that is sawed through lengthwise. You see the larger part at the end is full of little holes, like a sponge. This makes it light and strong. There is a hollow place in long bones filled with marrow. It also fills the spongy parts. Marrow is made of fat and cells.

You must not think that live bones look like one which has been lying out-of-doors a long time. Live bones are full of blood and have a pinkish color. They also have an outside skin, which can be peeled off, as you see in this picture.

A bone with the outside skin partly peeled off.

Amy: What are the bones made of?

End of a bone sawed open.

Mother: Of animal and earthy matter. You can take the animal matter out of a bone by burning it in the fire. It will then be white and brittle. If you soak a bone in a kind of acid, the earthy matter will come out, and it will then be so soft you can tie it in a knot like this. When children are very young, their bones are soft and easily bent. This is because there is more animal than earthy matter. Children sometimes get hard falls, and their bones bend but do not break. Some, when very young, have legs that are bent like a bow. This is caused by standing and walking before the bones are strong enough to bear the weight of the body, or by disease.

A bone tied in a knot, after the earthy matter has been removed by an acid.

In very old people the bones contain more earthy matter, and they break easily. Grand´fa-ther and grand´moth-er must be careful not to fall, for if they break a bone it will take a long time to heal.

When we take a baby, we should not lift him by his arms, and we must hold him so his bones will not grow out of shape. As he grows older, enough earthy matter will go into his bones to make them hard and strong.

Percy: But you said there was lime in the bones, mother.

Mother: Yes, the earthy matter is partly lime. The blood goes into the bones through tiny blood-vessels, and at all times of day and night the bones keep eating their breakfasts, dinners, and suppers of lime, which they find in the blood.

“We should not lift him by his arms.”

Helen: What kind of food is best for the bones?

Mother: Good whole-wheat bread will furnish them all they need. Peas and beans are also good.

Back-bone.

We will now look at the largest bones of our body frame, and see if we can learn something of their size and shape. We will not try to learn their hard names now, but will leave that till we are older.

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.

Reels of cotton.

Elmer: The boy with his hands in his pockets does not have a good figure.

Mother: No; and if he were to go into the army, the first thing he would have to learn would be to “straighten up,” and give his spinal column a chance to grow the right way.

Now we will look at the ribs. They are fastened to the spinal column at the back, and all but four are fastened to the breast-bone in front. There are twelve ribs on each side. There are two bones on the upper part of the back, which seem to dance every time you move your arm. These are the “shoulder blades.” They are thin, flat bones, which help make the shoulder joint. You can feel two bones near your neck in front, which are called “collar bones.” They are shaped much like the letter f, and serve to preserve the shape of the shoulders.

Ribs.

Amy: How many bones do we have in our arms, mother?

Bones of the arm.

Mother: There are three in each arm,—one from the shoulder to the elbow, and two from the elbow to the wrist. There are a large number of bones in the wrist and hand.

The pelvis.

The middle part of the body below the spinal column is called the pelvis. In this picture we see two curious bones. These are the hip bones. They are like the sills of a house, which, you know, are large and strong. There is a deep hole in each one as large as a toy teacup, which holds the round head of the leg bone. There are three bones in each leg, the same as in the arm, one from the hip to the knee, and two from the knee to the ankle, besides a funny little bone or cap which covers the knee. Then we come to the ankle bones and bones of the feet.

Helen: How do the bones stay in their proper places, mother? I should think they would fall apart.

Mother: They would if they were not tied together.

Elmer: But what are they tied with?

Bones of the leg and foot.

Mother: With strong white bands or cords called lig´a-ments. Perhaps you have seen them on the leg of a chicken. When a joint is “sprained,” that means the lig´a-ments are stretched or hurt in some way.

Amy: I should think the bones would get dry so they would squeak and rub hard against one another.

Wrist bones tied together.

Mother: So they would if the Maker of the body-house had not put soft cushions of gristle or car´ti-lage between them. A soft, thin skin covers them, which pours “joint water” over the ends, and keeps them oiled just right, so they bend easily, and never squeak at all. You have seen the driver of an engine oiling it so it would run easily and not wear out; but think of a machine which will mend and oil itself for seventy years without wearing out! We have a most wonderful frame. The Bible says, “Thou hast fenced me with bones and sinews,” and, “He knoweth our frame.” Sometimes if we are ill a long time “the bones that were not seen stick out;” but when we are well, flesh covers them over so we hardly know we have any bones at all.

I once read a poem which I will repeat for you. It may help you to remember how many bones we have and where they are:—

“How many bones in the human head?

Eight, my child, as I’ve often said.

How many bones in the human spine?

Twenty-six, like a climbing vine.

How many bones in the human chest?

Twenty-four ribs, and four of the rest.

How many bones in the human arm?

In each one, two in each forearm.

How many bones in the human wrist?

Eight in each if none are missed.

How many bones in the fingers ten?

Twenty-eight, and by joints they bend.

How many bones in the human hip?

One in each; like a dish they dip.

How many bones in the human knees?

One in each, the knee-pan, please.

How many bones in the ankles strong?

Seven in each, but none are long.

How many bones in the toes, half a score?

Twenty-eight, and there are no more.

And now altogether these many bones fix,

And they count in the body two hundred and six.

And now and then a bone I should think

That forms on a joint, or to fill up a chink,

A ses´a-moid bone, or a wormian, we call,

And now we may rest, for we’ve told them all.”