motor end-plate
Specialized region of muscle fiber membrane where motor neuron terminals form synapses, constituting the postsynaptic component of neuromuscular junction.
Full Definition
The motor end-plate is the highly specialized postsynaptic region of skeletal muscle fibers where neuromuscular transmission occurs. This structure contains high concentrations of nicotinic acetylcholine receptors, voltage-gated sodium channels, and other proteins essential for excitation-contraction coupling. The end-plate region is characterized by deep synaptic folds that increase surface area and concentrate receptors opposite the presynaptic nerve terminal. Pathological changes at the motor end-plate are central to neuromuscular junction disorders, including receptor destruction in myasthenia gravis, structural abnormalities in congenital myasthenic syndromes, and degenerative changes in aging. Electrophysiologically, the end-plate generates characteristic potentials that can be recorded during needle EMG examination.
Usage
Usage note: Hyphenate 'end-plate' consistently; 'motor' can be dropped when context is clear.
In Context
- "Electron microscopy revealed simplified motor end-plate architecture in this congenital myasthenic syndrome." — Pathology report
- "End-plate noise increased during the EMG examination, suggesting neuromuscular junction irritability." — Electrophysiology report