| A | B |
|---|
| organ that contracts and gets shorter | muscle |
| tough outer covering of bone | periosteum |
| joint problem common in the US | arthritis |
| number of bones in a baby | 300 |
| number of bones in an adult | 206 |
| number of muscles in an adult | 600 |
| involuntary muscle | smooth |
| flexible strong tissue | cartilage |
| most common joint | gliding |
| white blood cell | lymphocyte |
| voluntary muscle | skeletal |
| hard, strong bone | compact |
| lightweight bone | spongy |
| destroy bones | osteoclasts |
| build bones | osteoblasts |
| holds bone to bone | ligament |
| holds muscle to bone | tendon |
| where bones meet | joint |
| heart only muscle | cardiac |
| one bone rotates around another | pivot |
| bump on one bone sits in another | ball and socket |
| joint that opens one way only | hinge |
