Globular heads of myosin filaments link the thick and the thin myofilaments together during contraction, which is why they are sometimes called:

Explanation

Option D is correct. The globular heads of myosin filaments link the thick and the thin myofilaments together during muscle contraction. This is why they are sometimes called cross bridges. The globular heads of myosin have an ATP-binding site and a myosin-binding site. When the muscle contracts, ATP binds to the ATP-binding site of the myosin head. This releases the myosin head from the actin filament. The myosin head then rotates, which causes the myosin-binding site to move away from the actin filament. This exposes the ATP-binding site, which allows ATP to bind again. Cross-connection refers to the formation of a bridge between the heavy and thin filaments within a muscle sarcomere during muscle contraction. Cross-connection is a key component of muscle contraction. It is the force generated by the cross-connection that causes the thick and thin filaments to slide over each other. The cross-connection is formed when the myosin heads bind to the actin filaments. The myosin heads have two binding sites: one for ATP and one for actin. When the myosin head binds to the actin filament, it releases the ATP and uses the energy from the hydrolysis of ATP to move. This movement of the myosin head causes the cross-connection to form.