The swinging cross bridge theory for muscle contraction envisages that the myosin cross bridge binds to the actin filament in ... the crystal structure of the smooth muscle myosin motor-domain ...

seen as a cross-bridge between actin and myosin filaments in muscle, acts as the motor domain of the molecule and pulls actin filaments along by repetitive conformational changes coupled to ATP ...

When stimulated by the autonomic nervous system to contract from the release of hormones or other chemical signals, smooth muscle cells shorten via the movement of actin and myosin myofilaments.