Describe the process of synaptic transmission at the neuromuscular junction.

The neuromuscular junction describes the chemical connection between a presynaptic nerve, and the muscle fibre membrane (sarcolemma). Depolarisation of the presynaptic nerve membrane (by propagation of an action potential) causes the release of the neurotransmitter acetyl choline (ACh) into the junctional cleft. ACh then diffuses across the cleft, binding to nicotinic ACh receptors on the adjacent muscle membrane. This binding causes the opening of cation channels, allowing the influx of sodium ions into the muscle fibre, and some (although significantly less) efflux of potassium ions into the extracellular space. This current flow results in the depolarisation of the sarcolemma, and hence the generation of the end plate potential.