During canal wall down mastoidectomy, the surgeon encounters the facial nerve at the second genu. The second genu of the facial nerve is located at the junction of which two segments?
- A Labyrinthine and tympanic segments
- B Mastoid and parotid segments
- C Tympanic and mastoid segments ✓
- D Geniculate and labyrinthine segments
Correct answer: C. Tympanic and mastoid segments
Explanation
The facial nerve second genu marks the junction between the horizontal (tympanic) segment and the vertical (mastoid) segment. This is a critical landmark in mastoid surgery. The first genu is at the geniculate ganglion where the labyrinthine segment ends and tympanic segment begins. The mastoid segment continues to the stylomastoid foramen.
Reference: Gray's Anatomy, 42nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.