How does a sarcomere work?

A sarcomere is the basic contractile unit of muscle fibers, composed of interdigitating thick (myosin) and thin (actin) filaments. During muscle contraction, the myosin heads bind to actin filaments, forming cross-bridges that pull the actin toward the center of the sarcomere, a process powered by ATP hydrolysis. This shortening of the sarcomere results in muscle contraction. The coordinated action of many sarcomeres in sequence allows for overall muscle movement.