Across
- 3. Involuntary muscle lining internal organs
- 5. Specialized muscle making up the heart
- 7. Hard, dense connective tissue storing calcium
- 8. Produces red and white blood cells
- 9. Animals with an internal skeleton
- 10. Animals without an internal skeleton
- 12. Voluntary muscle attached to bones
- 13. Condition causing brittle bones
- 15. Tough tissue connecting bones at joints
Down
- 1. Hard outer frame of some invertebrates
- 2. System made of bones and muscles
- 4. Muscle that flexes the elbow
- 6. Flexible, low-friction tissue between bones
- 11. Connects muscles to bones
- 14. Muscle that straightens the elbow