Stimulation of a muscle fiber by a motor neuron occurs at

The junction between a motor neuron and the sarcolemma of the muscle fibre is called the neuromuscular junction or motor-end plate. A neural signal reaching this junction releases a neurotransmitter (Acetyl choline) which generates an action potential in the sarcolemma. This spreads through the muscle fibre (through transverse tubules) and causes the release of calcium ions (from sarcoplasmic reticulum) into the sarcoplasm. Muscle fibre then undergoes contraction.