Gross Anatomy USMLE Step 1 Practice Question
A 37-year-old woman with multiple sclerosis presents with acute diplopia. Vital signs: BP 128/82, HR 88, RR 16, Temp 37.2°C, SpO2 98%. On examination, leftward gaze reveals failure of right eye adduction with left eye abducting nystagmus; convergence remains intact. Brain MRI shows a demyelinating lesion in the pontine region. She denies vertigo. Which structure is most likely affected?
Answer choices
- AMedial longitudinal fasciculusCorrect answer
- BDorsal columns
- CCorticospinal tract
- DSpinothalamic tract
- EOptic tract
- FParamedian pontine reticular formation (PPRF)
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