Selman, Metric study on depth of the…. mastoidectomy and posterior triangle (8). The surface marking of the tympanotomy(4). The area is entered mastoid antrum is the suprameatal triangle through a retroauricular tympanotomy flap, (Macewen's triangle) Figure 1 (8). and the electrode is introduced via a tunnel The boundaries of the triangle are: drilled in the suprameatal region superior Anteriorly: The post‐superior border of the to Henle's spine. The suprameatal approach bony external auditory canal along with the is a simple and safe technique that does suprameatal spine of Henle. This spine is not endanger the facial nerve or the chorda prominent landmark for the suprameatal tympani (5). triangle. Since the suprameatal triangle covers the a) Superiorly: The supramastoid crest. lateral wall of the mastoid air system, the b) Posteriorly: a vertical line drawn suprameatal triangle is of importance to tangential to the posterior margin of the otologic surgeons during mastoidectomy (6). external canal. The anatomical landmarks especially In adult this triangle lies 1.5 cm lateral to suprameatal crests on the outer surface of the mastoid antrum which the largest air the squamous part of the temporal bone cell in the mastoid bone (9). are of clinical importance as they are accepted as landmarks for some surgical Aim of this study approaches (7). To measure the depth of the sinus plate In vivo, identification of suprameatal that is an indicator for the distance triangle is by doing postural incision 0.5cm between the site of the mastoidectomy and behind the retroauricular sulcus which is sigmoid sinus. The assessment of this plate the exact site for operation on living may be used as a mark that possibly point patients in mastoidectomy. By removing toward avoidance of the bleeding the mastoid cortex with electric drill, the possibility during the surgical exact depth of the sinus plate is clarified. mastoidectomy. This study was designed to Drilling from suprameatal triangle was done assess the profitability of using simple in line of superior border of suprameatal parameters that could be obtained from the plan x‐ray of the skull. Superior border Red line Anterioinferior border Posterior border Green color line Blue line Figure 1: Diagrammatic illustration of suprameatal triangle (Macewen's) triangle (3). 87.