Left lateral inferior oblique view of skull. The mandible has been removed in this bony skull to provide views of multiple bones, fissures, foramina, and spaces. Anteriorly, the forehead, roof of the orbit, and anterior portion of the skull is formed by the frontal bone. It articulates at the midline with a pair of narrow nasal bones that, in turn, articulate with the maxillae. The maxillae form the central skeleton of the face. They form the floor of the orbit, contain the maxillary teeth and sinus, and contribute to most of the hard palate (the posterior one-third is made by the palatine bone). Just below the inferior orbital rim is the infraorbital foramen for neurovasculature to the lower eyelid, lateral nose, and upper lip. The zygomatic bone forms the lateral wall of the orbit and prominence of the cheek. Posterior to the frontal bone are the paired parietal bones. These, in turn laterally, join the squamous portion of the temporal bone and the greater wing of the sphenoid bone. Together, they form the shallow temporal fossa on the side of the head. The zygomatic arch connects portions of the zygomatic and temporal bones and forms the horizontal boundary between the temporal and infratemporal fossae. At this junction, marked by the infratemporal crest of the sphenoid, the greater wing of the sphenoid turns nearly horizontally medially to form the roof of the infratemporal fossa and contains the foramen ovale and spinosum. The pterygomaxillary fissure, a vertical space between the posterior surface of the maxilla and pterygoid process, marks the junction between the infratemporal and pterygopalatine fossae. Both fossae communicate with the floor of the orbit through the inferior orbital fissure, a space between the maxilla and greater wing of sphenoid. The anterior root of the zygomatic process of the temporal bone ends in front of the mandibular fossa, which contains the head of the mandible. At the posteromedial aspect of this fossa is the petrotympanic fissure for exit of the chorda tympani nerve. Posterior to the mandibular fossa is the external auditory canal contained within the tympanic part of the temporal bone. This canal is bounded posteriorly by the mastoid process. The clivus is located at the inferior midline in front of the foramen magnum. The foramen lacerum is a space between the clivus, petrous portion of the temporal bone, and greater wing of sphenoid. In life, its floor is filled by fibrocartilage. Similarly, the jugular foramen is a space between the petrous bone and occipital bone. (Image courtesy of AL Rhoton, Jr.)