The musculoskeletal system is made up of bones, joints, and muscles. This system gives the body form and support, and protects the body while allowing it to move. Basically, the muscles in this system perform three important body functions: the movement of body parts, maintenance of body parts, and production of body heat. These muscles all consist of a mass of protein fibers grouped together, and most are of mesodermal origin. And almost all of the muscle fibers you will ever have or need were present at birth. Nearly half of your body mass ....