The mastoid antrum in an adult is surgically approached through a triangular surface landmark bounded above by the supra-mastoid crest, behind by a vertical line drawn tangential to the posterior border of the external auditory canal, and in front by the posterosuperior margin of the bony canal. This landmark is called:

• A Trautmann's triangle
• B Macewen's triangle ✓
• C Henle's spine
• D Huguier's canal

Explanation

Macewen's (suprameatal) triangle is the standard surface landmark for locating the mastoid antrum in adults, where the antrum lies about 12 to 15 mm deep to it. Trautmann's triangle is an intracranial landmark bounded by the sigmoid sinus, superior petrosal sinus and arcuate eminence, relevant to accessing the posterior fossa. Henle's spine is only the suprameatal spine forming part of the anterior boundary, not the whole triangle.

Reference: Dhingra's Diseases of Ear, Nose and Throat, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.