Figure 4: Diagram showing hypothetical attachment-detachment cycle between the myosin head extending from myosin filaments and the corresponding myosin-binding sites on actin filaments. The periodicity of myosin heads differs from that of myosin biding sites on actin filaments, so that the attachment-detachment cycle takes place asynchronously. The myosin head first attaches to actin filament (top diagram), changes its configuration to move actin filament to he right (middle diagram), and then detaches from actin filament (bottom diagram) [11].