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DictionarySeemyoneural junctionEncyclopediaSeeneuromuscular junctionmotor endplate
mo·tor end·platethe large and complex end formation by which the axon of a motor neuron establishes synaptic contact with a skeletal muscle fiber (cell); several terminal branches of a motor axon end in irregular, club-shaped synaptic end formations, each of which is bedded in its own troughlike depression of the muscle fiber's surface; the postsynaptic membrane, the sarcolemma that forms the bottom of the trough, is greatly increased in surface area by deep infoldings protruding into the underlying cytoplasm of the muscle fiber; the subsynaptic interval between the plasma membrane of the axon terminals and the sarcolemma is filled with an amorphous substance; the trough is closed off toward the surface by the Schwann sheath, which peels away from the axons as the latter enter the trough and thus forms a lid over the trough; the slight bulge of this closure plate corresponds to Doyère eminence. Synonym(s): sole-plate endingmo·tor end·plate (mō'tŏr end'plāt) The large and complex end-formation by which the axon of a motor neuron establishes synaptic contact with a striated muscle fiber (cell). motor endplate The point of junction of a motor nerve fibre and a muscle fibre. The motor endplate is a modified area of the muscle fibre membrane at which a synapse occurs. A motor nerve axon ending may have up to 50 synaptic knobs (boutons) but a single muscle fibre has only one endplate. The neurotransmitter is acetylcholine.motor endplate see ENDPLATE, MOTOR.mo·tor end·plate (mō'tŏr end'plāt) The large and complex end-formation by which the axon of a motor neuron establishes synaptic contact with a striated muscle fiber (cell). |