motor unit potential
Also written as: MUP
The electrical waveform recorded from a single motor unit during needle EMG examination, reflecting the activity of all muscle fibers innervated by one motor neuron.
Full Definition
A motor unit potential (MUP) represents the summated electrical activity of all muscle fibers belonging to a single motor unit, as recorded by needle electromyography. Normal MUPs have characteristic parameters including duration (5-15ms), amplitude (200μV-2mV), and phases (2-4). Abnormal MUPs can indicate various neuromuscular disorders: short-duration, low-amplitude, polyphasic potentials suggest myopathy, while long-duration, high-amplitude potentials indicate neurogenic disorders. Clinical editors should note that MUP analysis is fundamental to EMG interpretation and requires precise documentation of morphological characteristics for accurate diagnosis.
Usage
Usage note: May be abbreviated as MUP; ensure morphological parameters are consistently reported.
In Context
- "Motor unit potentials showed increased duration and amplitude consistent with chronic denervation." — EMG report
- "The MUPs demonstrated normal morphology and recruitment pattern." — Neuromuscular assessment