Hinge joint of the elbow.
1 humerus 2 ulna
The shoulders and hips can be moved in every direction. The upper ends of the arm and leg bones are round like half a ball. They fit into cups on the shoulder and hip bones. They are very smooth, and are oiled like the hinge joints. The joints are made to work very smoothly and easily.
184. Bones out of joint.—When the ends of bones are torn away from each other, the bone is out of joint. Then the bone cannot be moved without great pain. It should be put back in place at once and kept there by splints and bandages. A person is less liable to have his joints out of place than he is to have his bones broken.
185. Sprains.—Sometimes a joint is turned too much. This stretches the flesh around the joint, and makes it very tender and painful. This is a sprain. When you sprain a joint, you should put it in hot water for an hour or two. Then keep it still for a few days.
186. Why bones and joints grow wrong.—While bones and joints are growing they can be made to take any shape we please. They cannot be bent all at once, but if we hold them in one way much of the time, they will keep that shape. Some boys and girls sit with their backs bent forward and lean against the desk as if they were too lazy to sit up. When they grow up, they will be bent and round-shouldered. You should sit and stand straight. Then you will grow tall and straight and strong. A soldier has square shoulders and walks erect because he is drilled until his bones and joints grow in the proper shape. As you stand straight with your feet together, your two big toes, your two ankles, and your two knees should touch each other.
If you wear tight shoes and press the toes out of shape, they will soon grow so. Nearly every one's feet are out of shape from wearing short, pointed shoes. Your toes should be straight and not cramped by the shoe. If you wear narrow shoes, you may harm your feet. It is better to have one's feet useful, even if they are large, than to make them small and useless.
WHAT WE HAVE LEARNED
1. Bones make the body stiff, and give it form.