CHAPTER XIX.BONES, SKELETON, ETC.

The bones are the frame-work of the body. Like the muscles, they are generally found in pairs, one for each side of the body. Their number is more than two hundred. When joined together, in their proper position, they make a skeleton, as shown in the picture on page115, where the names of the principal bones are given.

THE SKULL.—(1)Frontal Bone, (2)Parietal Bone, (3)Temporal Bone, (6)Superior Maxillary(Upper Jaw)Bone, (7)Malar Bone, (9)Nasal Bone, (10)Inferior Maxillary(Lower Jaw)Bone

A bone is composed of animal and mineral substance. The animal part gives it elasticity, and the mineral, hardness. In youth there is more of the animal substance, but it grows less as a person becomes older. This explains why the bones of a child do not break so readily as those of an aged person, and why,when broken, they heal much sooner. Sometimes when a very old man or woman has a limb broken, the bone will not “knit,” or heal at all.

THE CHEST.—(a)The Sternum or Breastbone, (btoc)the True Ribs, (dtof)the False Ribs, (g, h)the Floating Ribs, (itok)the Dorsal Vertebræ.

THE HAND.—(1)Radius, (2)Ulna, (4-4)Bones of the Wrist, (5-5)Bones of the Hand, (6-6)Bones of the Fingers.

The movable joints are joined by bands or ligaments, which are very strong. They often refuse to yield, when the bone to which they are fastened is broken. If a ligament is strained or hurt, a “sprain” is caused, which may be as bad as a broken bone.

Boys and girls are apt to form bad habits by which some of the bones become misshapen. You should hold your head erect, but not thrust forward; keep the chest expanded and the shoulders well back. You will find, after awhile, that this healthful posture is the most pleasant you can take, and it will give you the form which nature intends all of us to have.

What are the bones? How are they generally placed? How many bones have you? What is a skeleton?

Of what is a bone composed? What does the animal part give? The mineral? Why is the bone of a child less liable to break than that of an older person? What takes place sometimes when the bone of an old person is broken?

How are the movable joints joined? What is said of the strength of a ligament? What is a “sprain”?

What are boys and girls apt to do? What is the proper posture? What will you find?

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