| Term | Definition |
| skeleton | The inner framework made up of all the bones of the body. |
| ligament | Strong connective tissue that holds bones together in movable joints. |
| compact bone | Hard, dense bone tissue that is beneath the outer membrane of a bone. |
| marrow | The soft connective tissue that fills the internal spaces of the bones. |
| vertebrae | The 26 small bones that make up the backbone. |
| cartilage | A connective tissue that is more flexible than a bone and that protects the ends of bones and keeps them from rubbing together. |
| spongy bone | Layer of bone tissue having many small spaces and found just inside the layer of compact bone. |
| osteoporosis | A condition which the body's bones become weak and break easily. |
| joint | A place in the body where two bones come together. |
| fracture | A break in a bone. |
| sprain | An injury in which the ligaments holding bones together are stretched to far and tear. |
| magnetic resonance imaging | A method for taking clear images of both bones and soft tissues of the body. |
| arthritis | A disease of the joints that makes movement painful. |
| arthroscope | A slim, tube-shaped, surgical instrument that doctors use to diagnose a problem in the joint. |
| X-ray | A form of energy that travels in waves. |
| dislocation | An injury in which a bone comes out of its joint. |