Muscles are attached to bones and bones have joints which allow the body to move. A muscle is attached to bones via a tendon. Muscles that work in pairs are known as antagonistic muscles. When muscles contract, they pull the bone to which they are attached closer. As one muscle contracts, the other relaxes.
Muscles are effects which respond to nervous impulses.
Peristalsis is the movement of muscles to force food along the gut. This happens without our control. Move in one direction like a hinge. Up and down.