Computed tomography of Körner's septum and petrosquamosal suture.

The petrosquamosal suture and septum are formed at the junction of the petrosal and squamosal bones. The suture crosses the temporal bone obliquely in an anteroposterior direction. Anteriorly, its anatomy is complex due to the convergence of two other bones: the sphenoid and the tympanic. Posteriorly, the petrosquamosal (Körner's) septum has a distinctive appearance on computed tomography (CT). While the anterior attachment of the septum can be used as a guide during surgery, the surgeon must also be aware preoperatively that large septa on CT can be mistaken for the medial mastoid wall. Prior to CT, Körner's septum has been used as a roentgenographic landmark to determine cholesteatoma extension. We now propose that the septum can also be used as a gauge for squamomastoid sclerosis.