how many muscles work together to move a bone

Dear Student,
Bones don't work alone and they need help from the muscles and joints. Muscles pull on the joints, allowing us to move.

Muscles move body parts by contracting and then relaxing. Muscles can pull bones, but can't push them back to their original position. That is why they work in pairs of flexors and extensors. 

For example, the biceps muscle is a flexor, and the triceps is an extensor.

• To lift the forearm, the biceps contracts and the triceps relaxes.
• To lower the forearm, the triceps contracts and the biceps relaxes.

The arm is flexed by the contraction of the biceps muscle. The triceps muscle relaxes as the biceps contracts and the arm bends at the elbow. The biceps muscle becomes thicker and shorter as the arm bends at the elbow joint.

 
Regards