Left lateral superior view of subtemporal osteotomy. The scalp and temporalis muscle have reflected off the skull. For orientation, the lower left corner of the image is superior; the lower right corner is anterior. Portions of skull bone have been exposed, including the parietal bone superiorly, a portion of the frontal bone anteriorly, the squamous portion of the temporal bone posterolaterally, and the greater wing of the sphenoid interposed between frontal and squamosal bones. The intersection of these four bones is the pterion. (Image courtesy of AL Rhoton, Jr.)