In Bell palsy, the oedematous inflamed facial nerve becomes compressed at the segment of the facial canal that is narrowest and where the nerve completely fills the bony canal. Which segment is this?

• A Labyrinthine segment ✓
• B Tympanic segment
• C Mastoid segment
• D Meatal segment within the internal acoustic meatus

Explanation

The labyrinthine segment runs from the fundus of the internal acoustic meatus to the geniculate ganglion and measures roughly 0.68 mm in diameter, the narrowest part of the fallopian canal, with the nerve occupying the entire lumen and receiving blood solely from the petrosal branch of the middle meningeal artery without anastomosis. Oedema here produces maximal compression, explaining why decompression targets this segment. The mastoid segment is the widest, ruling out C.

Reference: Cummings Otolaryngology Head and Neck Surgery, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.