EDX-13 · Neuromuscular Junction Disorders

Neuromuscular Junction Disorders. Part of the Electrodiagnostics series of the Reflex PM&R Board Review podcast. Audio correction: In the audio: divide the actual end plate potential generated by the threshold required to fire — Correct: The safety factor is not a voltage ratio at all. It is quantal: the number of quanta released per impulse divided by the minimum number needed to trigger a muscle action potential, conventionally about 3 to 5. Quantal content is normally 50 to 300 per impulse and each quantum contributes 0.5 to 1.0 mV, so the endplate potential comfortably exceeds what threshold requires. Dividing an endplate potential by a threshold membrane potential is not the definition and does not yield 3 to 5. The written chapter is correct. Full correction register: https://www.reflexpmr.com/errata. The full companion chapter and a linked board-style Q-bank set for this topic are at https://www.reflexpmr.com/read/EDX-13.