The work is under the mind control of the somatic nervous system (SNS), so the body can force or power in mind. The function of bone to muscle action. Muscle, bone is a double contrast conditions. New antagonism that effect. So when one side muscle contraction. Another side to loosen the muscles. The contraction of the muscle tension caused by the bone movement. Because the muscle to the bone with ligaments, bones stick. Ligaments, bone tissue, toughness and tensile strength or weight.