ABSTRACT
To describe the anatomy of the Korner's septum [KS] or petrosquamosal suture [PSS], its incidence, variations in normal and inflamed middle ears, and to evaluate its clinical importance. Review of 100 CT scans temporal bones were done to determine the degree of visualization of Korner's septum [KS]. Cadaveric dissection of 100 temporal bones were done in temporal bone dissection laboratory of Ain Shams University Specialzied hospital in addition to 100 mastoidectomies performed in the ENT inpatient department. KS or PSS is not only a bony plate dividing the mastoid cells at the level of the antrum, but is also a lamina starting from the posterior aspect of the glenoid fossa that extends above the middle ear cavity and courses inferiorly lateral to facial canal and proceeds to mastoid apex. Korner's septum was seen radiologically in 26% of CT scans of temporal bones, and in 25% of temporal bone specimens. Clinically "KS" was seen in [29%] of cases with COM and in [24%] in cases without COM with a total incidence of [28%]. Frequently there was a hidden cholesteatoma or cholesterol graunloma behind the septum. Rarely the cog [anterior part of the septum] may extend to fix the ossicels. KS is an imporatn anatomic observation in patients with chronic otitis media, it may contribute to middle ear infection and it may hide cholesteatoma or cholesterol granunloma behind it which may be missed if superficial compartment was sclerosed