A cross bridge is present in the overlap of thick myosin filaments and thin actin filaments in a muscle fibre. They may be present when the muscle is contracted or when the muscle is relaxed, and they occur in all types of muscle cells. A cross bridge is a link between the F - actin filament and the myosin head, and it is essential for contraction of a muscle. When the muscle is in a contracted state, the cross bridge must form and dissociate rapidly. This mechanism pulls the thin filaments towards the centre of the sarcomere and creates what is known as the sliding filament theory.
- ↑ This is a reference to: Wayne M. Becker (2009) The World Of The Cell. Pearson Benjamin Cummings : p 466- p467