Neuroanatomy USMLE Step 1 Practice Question
A 67-year-old man with hypertension and diabetes presents to the emergency department with acute onset of right-sided weakness affecting the arm and leg equally. His wife reports he had sudden difficulty speaking and facial drooping on the right side. On neurologic examination, the patient has right facial droop sparing the forehead, right arm weakness (3/5), right leg weakness (3/5), and intact sensation throughout. His pupils are 3 mm, equal, and reactive to light bilaterally. Cranial nerve examination reveals normal extraocular movements and no ptosis. MRI with diffusion-weighted imaging shows an acute ischemic stroke in the ventromedial midbrain on the left side. Which of the following anatomic structures is most likely responsible for the patient's motor deficit?
Answer choices
- ALeft corticospinal tractCorrect answer
- BLeft superior cerebellar peduncle
- CLeft medial lemniscus
- DLeft oculomotor nerve fascicles
- ELeft substantia nigra
- FLeft red nucleus
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