| A | B |
|---|
| skeleton | the system of bones that supports and protects the body and the organs in it |
| skull | bones of the face joined together with the bones that protect the brain |
| bone marrow | a soft material inside the long bones of the arms and legs. Old blood cells are repaired and new blood cells are made here. |
| femur | the long bone in the thigh |
| cartilage | a solf bonelike material that bends |
| joint | the place where tow or more bones are joined together |
| ligaments | strong cords of tissue that hold bones together at joints |
| ball and socket joint | the kind of joint that allows the most movement of bones |
| hinge joint | the type of joint that allows bones to move back and forth |
| pivot joint | the type of joint that allows movement from side to side |
| fixed joint | the type of joint that does not move |
| tendons | a tough cord that attaches muscles to bones |
| voluntary muscles | muscles you can control |
| involuntary muscles | muscles you cannot control |
| Skeletal muscles | voluntary muscles that move bones |
| smooth muscles | involuntary muscles that make up the blood vessels, stomach, intestines, and other organs |
| Heart muscle | a special kind of involuntary muscle that makes up the heart |
| fracture | a crack or break in a bone |
| simple fracture | a break in a bone that does not push the bone through the skin |
| compound fracture | a break in a bone in which the bone pushes through the skin |
| sprain | an injury in which a ligament is stretched or torn |
| strain | an injury caused by overstretching a muscle or tendon |
| cramp | a sudden or strong contraction of a muscle |
