Right lateral view of articulated temporal, sphenoid, frontal, and zygomatic bones. The zygomatic arch is formed by the union of the temporal and zygomatic processes of the zygomatic and temporal bones, respectively. Deep to the zygomatic bone and arch is the temporal fossa which is occupied by the temporalis muscle and its neurovasculature. The pterion is a craniometric point deep within the temporal fossa that is formed by the union of the greater wing of the sphenoid, squamous portion of the temporal, frontal, and parietal bones. The pterion is a thin region of bone that overlies the anterior division of the middle meningeal artery. (Image courtesy of AL Rhoton, Jr.)