Put in order Acetylcholine diffuses across synapse and

attaches to ACh receptors on sarcolemma

Myosin heads bind to actin forming crossbridges

Nerve impulse reaches the axon terminal

Calcium ions are released from sarcoplasmic reticulum

Calcium ions bind to
regulatory proteins on actin, exposing binding sites for myosin

Actin filaments are pulled toward the center of the sarcomere

ACh causes change in membrane permeability to Na+ and K+; action potential is generated

Acetylcholine is released

The sarcomere shortens and the muscle contracts