RESUMO
Körner's septum (KS) or petrosquamosal lamina is a bony lamina beginning at the articular fossa, extending above the middle ear, and running inferiorly and laterally to the facial nerve canal as it proceeds to the mastoid apex. This septum marks the junction of petrous and squamous bones. The paper presents details of the anatomical structure of KS, which is most often present at the level of the head of the malleus and/or the anterior semicircular canal. Attention is paid to embryological aspects of temporal bone development that lead to the formation of KS. Two imaging techniques most frequently used to diagnose KS are described, high resolution computed tomography (HRCT) and cone-beam computed tomography. Also presented is a case report of a 6-year-old patient suffering from chronic otitis media who developed a cholesteatoma due to presence of KS, illustrated with HRCT images and intraoperative capture. The authors describe diagnostic difficulties associated with this anatomical variant in the middle ear. The article also discusses the more frequent occurrence of this clinical problem in ears operated on due to chronic inflammation, retraction pocket or tympanosclerosis in comparison to healthy ears.
