6.+HOW+DO+SOME+MUSCLES+WORK?

Every muscle moves in one direction. To move in another direction it needs another muscle that makes this contrary action. The muscles are usually arranged in pairs that are antagonistic.
 * The back tibialis lifts his foot to walk.
 * Stoideon pulls the head foward or turns.
 * Bicepsse contract to bend the arm.
 * More than 640 muscles move the body and maintain its position. Brachioradialis biceps helps bend the arm by pulling up the lower arm bones.
 * The triceps contract to extend the arm.
 * Pectoralis, pectoralis major pulls the arm forward and the body.
 * Quadriceps femoris group of muscles that hold the knee.