Educational objective: The oculomotor nerve (CN Ill) is most s | Uworld | Step 1

Educational objective: The oculomotor nerve (CN Ill) is most susceptible to injury from ipsilateral posterior communicating artery aneurysms. Aneurysmal compression of CN Ill produces mydriasis (due to superficial parasympathetic fiber damage) with diplopia, ptosis, and down and out deviation of the ipsilateral eye (due to somatic efferent fiber injury).