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
Paralysis of 3rd, 4th, 6th nerves with involvement of ophthalmic division of 5th nerve, localizes the lesion to: 
Select and explain. 
A. Cavernous sinus, B. Apex of orbit, C. Brainstem, D. Base of skull
A: Cavernous sinus
Answer: A: Cavernous sinus 
Explanation: 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