<prompt> Korners septum is seen in ?Petrosquamous sutureTemporosquamous suturePetromastoid sutureFrontozygomatic suture  <response>: Mastoid develops from squamous and petrous bone.Korners septum is persistence of petrosquamous suture in the form of a bony plate.Korners septum is surgically impoant as it may cause difficulty in locating the antrum and the deeper ells, and thus lead to incomplete removal of disease at mastoidectomy. Mastoid antrum cannot be reached unless theKorners septum has been removed. 