– Skeletal muscles are stimulated by somatic motor neurons
– Axons (long, threadlike extensions of motor neurons) travel from central nervous system to skeletal muscle
– Each axon divides into many branches as it enters muscle
– Axon branches end on muscle fiber, forming neuromuscular junction or motor end plate
▪ Each muscle fiber has one neuromuscular junction with one motor neuron
– Axon terminal (end of axon) and muscle fiber are separated by gel-filled space called synaptic cleft
– Stored within axon terminals are membrane-bound synaptic vesicles
▪ Synaptic vesicles contain neurotransmitter acetylcholine (ACh)
– Infoldings of sarcolemma, called junctional folds, contain millions of ACh receptors
– NMJ consists of axon terminals, synaptic cleft, and junctional folds
