According to the sliding filament model
A. Myosin cross-bridges attach to actin and pull
B. Actin cross-bridges attach to myosin and pull
C. Myosin cross-bridges push actin away
D. Actin cross-bridges push myosin away
A cross-bridge forms between actin and the myosin heads triggering contraction. As long as Ca++ ions remain in the sarcoplasm to bind to troponin, and as long as ATP is available, the muscle fiber will continue to shorten.
