During parotidectomy, the main trunk of the facial nerve is identified using the tympanomastoid suture line as a landmark. The nerve trunk lies at what depth relative to this suture?

• A 1 mm medial and inferior to the suture
• B 1 cm deep to the midpoint of the suture
• C 5 to 7 mm deep and superior to the suture
• D 2 to 3 mm deep to the posteroinferior aspect of the suture ✓

Explanation

The main trunk of the facial nerve lies approximately 2 to 3 mm deep to the posteroinferior aspect of the tympanomastoid suture line. This is a critical surgical landmark used to locate the nerve during parotid surgery. The nerve exits the skull at the stylomastoid foramen just inferior to this suture, and dissection deep to this point allows safe identification of the trunk before it divides into its peripheral branches.

Reference: Bailey and Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.