In the nervous system, calcium ions crossing the gap between these cause a release of acetylcholine
These calcium ions cause the synaptic vesicles to fuse with the cell membrane, 
... neurotransmitters are released into synaptic cleft and diffuse to... [DOC] [TLE] Neuromuscular junction - Wikipedia [PAR] A neuromuscular junction (or myoneural junction) is a chemical synapse formed 
by the contact between a motor neuron and a muscle fiber.