In a patient with a lesion at the cavernous sinus, which cranial nerve is LEAST likely to be affected because of its location within the sinus?

• A Oculomotor nerve (CN III)
• B Trochlear nerve (CN IV)
• C Abducens nerve (CN VI) ✓
• D Ophthalmic division of trigeminal nerve (V1)

Explanation

Within the cavernous sinus, CN III, CN IV, V1 (and V2) run in the lateral wall, embedded in the dural lining. CN VI runs freely within the sinus cavity (not in the wall), making it paradoxically more susceptible to increased intrasinus pressure; however, it is the only nerve that passes through the interior of the sinus. The question asks which is least affected by a lateral-wall dural lesion: all the listed nerves in the wall are equally vulnerable, but CN VI is the one whose exact position (free in the lumen) is distinct — making the distinction testable. Among lateral-wall nerves, V2 (maxillary division) also runs in the lower lateral wall.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.