During mastoidectomy for chronic otitis media, the surgeon traces the facial nerve inferiorly from its second genu. At which landmark does the nerve turn from its vertical mastoid segment to exit the temporal bone?

• A Processus cochleariformis
• B Foramen ovale
• C Stylomastoid foramen ✓
• D Hiatus of the facial canal

Explanation

The facial nerve descends in the mastoid segment past the pyramidal eminence and exits the skull base through the stylomastoid foramen, where it gives off motor branches to the face. The processus cochleariformis marks the first genu at the geniculate ganglion region, not the distal exit. The hiatus of the facial canal transmits the greater petrosal nerve proximally, so it cannot be the distal landmark.

Reference: Cummings Otolaryngology: Head and Neck Surgery, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.