Petrosquamosal suture and lamina.

The junction of the petrosal and squamosal portions of the temporal lobe has important relationships that are of interest to the otologist. The resultant suture extends from the glaserian fissure across the top of the middle ear cleft and into the mastoid portion of the temporal bone. It may permit quick passage of infection from the middle ear to the middle cranial fossa. The petrosa may override the squama, forcing it down into the tympanum, where it could cause malleus fixation and a conductive type hearing loss. In the mastoid the suture is identifiable on the surface, but in the interior it is represented by the petrosquamosal lamina. The deeper portion in the petrosal portion of the mastoid may be easily overlooked in surgery of the mastoid and may lead to facial nerve injury.