Inferior view of skull base. The maxilla is the central bone of the face and contains the largest paranasal sinus, the maxillary sinus. It also forms the principal part of the hard palate (the horizontal part of the palatine bone forms the posterior border of the hard palate). Behind the central incisors is the incisive foramen. Medial to the maxillary molar teeth is the greater palatine foramen. These transmit the neurovascular supply to the hard palate.  The pterygoid processes of the sphenoid are located posterior to the dental arch and form the medial boundary of the infratemporal fossa. The undersurface of the greater wing of the sphenoid forms the roof of this fossa and contains the foramen ovale and spinosum. The infratemporal fossa is continuous with the temporal fossa superiorly through the space between the zygomatic arch and lateral skull. The vomer is a midline bone that attaches from the inferior surface of the body of the sphenoid to the superior surface of the hard palate. It is the posterior border of the nasal septum. Lateral to it are the choanae; passageways connecting the nasal cavity with the nasopharynx. The foramen lacerum is a space bounded by the apex of the petrous temporal bone, the greater wing of the sphenoid, and the clivus. Its floor is filled in life by fibrocartilage. The petrous bone contains the opening of the carotid canal and posterior to its external opening is the jugular foramen, a space between the petrous bone and occipital bone. Behind the root of the zygomatic arch is the mandibular fossa for articulation with the mandibular condyles. Posterior to this fossa are the styloid and mastoid processes with the stylomastoid foramen between them for exit of the facial nerve. The mastoid notch is located on the medial surface of the mastoid for attachment of the posterior digastric muscle. Medial to this notch is the occipital groove for the occipital artery. The occipital bone forms the posterior aspect of the skull. It contains the large foramen magnum, the occipital condyles for articulation with the atlas, and nuchal lines (superior and inferior) and the external occipital protuberance for muscle and nuchal ligament attachments. (Image courtesy of AL Rhoton, Jr.)