Immediately following the arrival of the stimulus at the axon terminal of a motor neuron there is a short period called the period during which the neurotransmitter is released by exocytosis, diffuses across the synaptic cleft, and binds to its receptors.

latent

Explanation:

A single action potential from a motor neuron triggers a single contraction in the muscle fibers of its motor unit. There is a brief delay between the application of the stimulus and the beginning of contraction. This delay is termed the latent period.

As the stimulus arrives axon terminal of a motor neuron, the resultant muscle action potential is propagated over the sarcolemma as the neurotransmitter is released in the synaptic cleft and binds to its receptors. There is a release of calcium ions from the sarcoplasmic reticulum to trigger excitation. During the latent period, muscles do not contract. The contraction period occurs once the latent period is over.