During tympanoplasty, the surgeon elevates a flap off the promontory and brisk bleeding is noted from vessels on its surface. A nerve coursing on the promontory that carries preganglionic parasympathetic fibres to the otic ganglion via the lesser petrosal nerve is:

• A Nerve of Arnold
• B Nerve of Wrisberg
• C Tympanic branch of the glossopharyngeal nerve ✓
• D Greater petrosal nerve

Explanation

Jacobson's nerve, the tympanic branch of CN IX, courses over the promontory in grooves called sulci tympanici and forms the tympanic plexus along with sympathetic fibres from the caroticotympanic nerves. Its parasympathetic fibres regroup as the lesser petrosal nerve to reach the otic ganglion. Arnold's nerve is the auricular branch of vagus, Wrisberg's nerve is the intermediate nerve of VII, and the greater petrosal nerve does not traverse the middle ear.

Reference: Gray's Anatomy, 42nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.