Basically, the action potential travels down the axon of the neuron and to the axon terminal. This is the axon terminal of the presynaptic neuron cell. Now, once the action potential arrives, it indirectly causes the release of these synaptic vesicles that carry a special type of chemical known as neurotransmitter. And a specific type of neurotransmitter involved in the neuromuscular junction is acetylcholine. So acetylcholine is released into this space known as Arisynaptic cleft. And it goes on and binds to a receptor protein channel found on the muscle cell, the postsynaptic membrane.