Which cranial nerve has the longest intracranial (subarachnoid) course, making it particularly vulnerable to raised intracranial pressure and head trauma?
- A Abducens nerve ✓
- B Trochlear nerve
- C Oculomotor nerve
- D Optic nerve
Correct answer: A. Abducens nerve
Explanation
The abducens nerve has the longest intracranial course of all cranial nerves, running from the pontomedullary junction up along the clivus beneath the dura, over the petrous apex through Dorello's canal into the cavernous sinus. This long course explains why sixth nerve palsy is a classic false-localizing sign in raised intracranial pressure. The trochlear nerve has the longest course inside the dural wall of the cavernous sinus, not the subarachnoid space.
Reference: Gray's Anatomy, 42nd ed.
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