2. Some bones are long, some round, and some flat. All are hard and springy.
3. Some bones are hinged together. The hinge is a joint.
4. The ends of bones in joints are rounded and smooth, and are oiled with a liquid like the white of an egg.
5. Some bones are bound together by springy pads, as in the backbone.
6. Bones can be broken. They will grow together again themselves.
7. Joints can be put out of place; then we must put them back.
8. If joints or bones are kept in wrong positions they will grow into bad shapes. Tight shoes deform the feet.