This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
[{'content': 'Paralysis of 3rd, 4th, 6th nerves with involvement of ophthalmic division of 5th nerve, localizes the lesion to: \nSelect and explain. \nA. Cavernous sinus, B. Apex of orbit, C. Brainstem, D. Base of skull', 'role': 'user'}, {'content': "Answer: A \nExplanation: CN III, IV, V1, V2, and VI and postganglionic sympathetic fibers en route to the orbit all pass through the cavernous sinus. Ref:Snell's Clinical Anatomy, 7th Edition, Pages 798-800", 'role': 'assistant'}]