A 34-year-old woman sustains a fracture of the petrous part of the temporal bone. She reports a persistently dry eye on the affected side with reduced tear production, though blinking and corneal sensation are intact. Which nerve was most likely injured?

• A Deep petrosal nerve
• B Greater petrosal nerve ✓
• C Lesser petrosal nerve
• D Nerve of the pterygoid canal distal to its formation

Explanation

Preganglionic parasympathetic fibres for the lacrimal gland leave the facial nerve at the geniculate ganglion as the greater petrosal nerve, cross the middle cranial fossa, join the deep petrosal nerve to form the nerve of the pterygoid canal, and relay in the pterygopalatine ganglion. Injury at the geniculate ganglion or along the greater petrosal nerve abolishes lacrimation while sparing facial muscles if the injury is proximal to that point. The deep petrosal nerve carries sympathetic fibres, which do not drive tear secretion.

Reference: Gray's Anatomy for Students, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.