While performing a cortical mastoidectomy, a trainee encounters an unexpected plate of dense bone deep to the cortex and mistakes it for the antrum floor, abandoning the dissection prematurely. This plate represents persistence of which embryological structure?

• A Petrosquamous lamina, also called Korner's septum ✓
• B Petrosal ridge of Gruber
• C Tegmen tympani
• D Solid mastoid of the infant

Explanation

Korner's septum is a persistent petrosquamous lamina, the fusion line between squamous and petrous portions of the temporal bone, which may appear as a false floor of the mastoid antrum. The inexperienced surgeon who stops here leaves disease behind, since the true antrum and air cells lie deeper. The tegmen tympani roofs the middle ear cleft, Gruber's ligament is at the petrous apex, and the infantile solid mastoid is not a discrete bony plate.

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.