A 26-year-old woman complains of early fatigue and weakness in doing strenuous activity. Her symptoms are worse near the end of the day. She appears well, muscle bulk, tone, and reflexes are normal. Handgrip strength decreases with repetitive testing.For the above patient with muscle weakness, select the most likely anatomic site for the disorder
Diurnal fluctuations and pathologic fatigue are common in disorders of neuromuscular transmission (e.g., myasthenia gravis). (Ropper, pp. 1250-1251)
anterior horn cell
peripheral nerve
neuromuscular junction
muscle
C.N.S.