How does muscle contraction take place?

First of all an action potential reaches the end of a motor neuron and the neurotransmitter acetylcholine is then released into the synapse. An action potential is initiated in the muscle cellSarcoplasmic reticulum releases calcium ions into the sarcoplasm. Calcium ions bind to troponin on actin.The activated troponin reacts with tropomyosin at the binding sites on actin exposing the binding sites. This allows myosin heads to form cross bridges by binding with actin. ATP attaches to the myosin head causing them to break the cross bridges detaching them from the binding sites.ATP is hydrolysed to ADP and phosphate causing the myosin heads to change their angle. The heads are now said to be cocked. The heads attach to binding sites on the actin that are further for the centre of the sarcomere than the previous site.The ADP is release and the heads push the actin filament inwards towards the centre of the sarcomere.