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NEUROPHYSIOLOGY

Synaptic Transmission: Neuromuscular Junction

r

Acetylcholine receptor

vesides

MyofibrHs

Synaptic cleft

Postsynaptic membranę

Junctional told

Sarcoplasm

AcetylchoBne receptor sites

Myelin sheath Neurilemma Axopłasm Schwann celi MiitKhondria Basement membranę

celi

membranę

Figurę 2.S Structure of the Neuromuscular Junction

Motor axons (hal synapsę on skeletal muscle form expanded ternie nals called neuromuscular junction* (motor endplates). The motor axon loses its myelin sheath and expands into a Schwann cełl-invested synaptic terminal thal resides within a trough in the muscle fiber. Acetylcholine-containing synaptic vesides accumulate adjacent to the presynaptic membranę and, when appropriately stim-ulated, release their neurotransmitter into the synaptic defl. The transmitter then binds to receptors that modiate depolarization of the muscle sarcolemma and initiate a muscle action potential. A single muscle fiber has only one neuromuscular junction, but a motor axon can innervate multiple muscle fibers.

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