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.', 'role': 'assistant'}]