During cortical mastoidectomy, the surgeon identifies the angle formed between the tegmen tympani above and the sigmoid sinus plate behind. This angle, which contains the sinodural (Citelli's) angle cells, lies adjacent to which clinically important structure?
- A Antrum of the mastoid
- B Endolymphatic sac ✓
- C Facial nerve second genu
- D Petrosquamous suture
Correct answer: B. Endolymphatic sac
Explanation
The sinodural angle of Citelli lies between the tegmen plate superiorly and the sigmoid sinus plate posteriorly. Its contained air cells lie close to the endolymphatic sac and the superior petrosal sinus region, and complete exenteration of these cells is important in radical procedures for disease clearance. The mastoid antrum lies anterior to this angle, deep to Macewen's triangle, not within it.
Reference: Gray's Anatomy, 42nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.