Body movement is controlled by skeletal muscle. About 650 skeletal muscles move the arms, legs, fingers and toes.
The muscle is attached to the bones via flexible cords, called tendons. The series of ridges across the muscle show its two interlocking proteins, actin and myosin. When the actin slides over myosin, the muscle contracts. The darker areas show actin and myosin overlapping, while the paler areas show actin alone. When skeletal muscle contracts, its tendon pulls on bone to make the body move.
Muscles are ennervated by motor neurons. A motor neuron and the muscle fibers ennervated by it form a motor unit. Size of motor units varies in the body, depending on the function of the muscle. Fine movements (eyes) have fewer muscle fibers per neuron to allow for fine movement. Muscles that require a lot of strength have many muscle fibers per unit. The body can control strength by deciding how many motor units it activates for a given function.
Picture Credit : Google
