Left lateral view of skull. The lateral skull is outlined to indicate location of cuts for a pterional approach to the brain. The frontal bone is anterior and articulates with the zygomatic bone anterolaterally, with the greater wing of the sphenoid bone laterally, and the parietal bones posteriorly. The coronal suture separates the frontal and parietal bones. The squamous portion of the temporal bone is a "scale-like" piece of bone that forms much of the temporal fossa and includes the zygomatic process. This process unites with the temporal process of the zygomatic bone to form the zygomatic arch. Superior to the squamous temporal bone is the parietal bone. They unite at the squamosal or temporoparietal suture. The pterion is a point of intersection of frontal, sphenoid, parietal, and temporal bones and  marks the location of the anterior branch of the middle meningeal artery internally. The external auditory or acoustic meatus is part of the tympanic portion of the temporal bone and connects the external ear to the tympanic membrane and cavity. The mastoid process of the temporal bone is posterior to this meatus. (Image courtesy of AL Rhoton, Jr.)