1. A tendon is a strong, fibrous connective tissue that attaches muscle to bone.
2. An extensor is a muscle that straightens a joint or extends a body part.
3. A flexor is a muscle that bends a joint or flexes a body part.
4. There are about 600 muscles in the human body.
5. Tendons attach muscles to bones, while ligaments connect bones to other bones at joints.
6. Muscles must contract (shorten) and relax to move a bone.
7. Muscles work together in pairs or groups; when one contracts to move a bone, its opposing muscle relaxes, allowing controlled movement.
8. The biceps muscle of the arm is a flexor.
9. The triceps muscle of the arm is an extensor.
10. Muscles are attached to bones and contract to pull on them; they cannot push, so they are always relaxed when their opposing muscle contracts to move the bone in the opposite direction.
Skill Challenge:
2. The triceps at the back of the upper arm is actually a group of three muscles. This arrangement allows for greater force generation and more precise control over the extension of the elbow joint, enabling powerful and coordinated movements like pushing or throwing.
3. Ball-and-socket joints have a team of many muscles surrounding them. This is necessary because these joints allow movement in multiple directions (flexion, extension, abduction, adduction, rotation). A single muscle can only pull in one direction; therefore, multiple muscles are required to control movement in all possible directions around the joint.
Parent Tip: Review the logic above to help your child master the concept of muscle system worksheet.
