The muscles in your body are connected to your bones by tough, fibrous tissues called tendons. When you move a muscle, the force of this movement passes from the muscle through its associated tendon. The tendon uses this force to initiate movement of the connected bone and associated joint. Together, the muscles, bones and joints involved in this process are commonly referred to as the musculoskeletal system. Most of the muscles and tendons in this system have attachments to the bones in your arms, legs, chest, abdomen, face and neck.