Osseous Relationships of the Infratemporal Fossa, Sphenoid Bone, and Mandible. A, Anterior view of the sphenoid bone. The anterior opening of the vidian canal is situated inferomedial to the foramen rotundum. B, Posterior view of the sphenoid bone. The pterygoid processes of the sphenoid descend perpendicularly from the region where the greater wings unite with the body. Each process consists of the medial and a lateral plate, the upper parts of which are fused anteriorly. The medial pterygoid plate is narrower and longer than the lateral; its lower end curves laterally into a hook-like process, the pterygoid hamulus, around which the tendon of the tensor veli palatini is deflected. C, Lateral view of the infratemporal fossa. The pyramidal process of the palatine bone fits into the angular interval between the lower ends of the pterygoid plates. The medial portion of the tympanic part of the temporal bone forms the posterior boundary of the petrotympanic fissure. D, Inferior view of the infratemporal fossa. The sulcus for auditory tube, which is the attachment site of the cartilaginous part of the Eustachian tube to the cranial base, is located on the extracranial surface of the sphenopetrosal fissure, anterolateral to the foramen lacerum and posteromedial to the foramen ovale and spinosum. The foramen ovale, which is irregularly oval, lies close to the upper end of the posterior margin of the lateral pterygoid plate. E, Lateral view of the mandible. The oblique line in the mandible runs upward and backward from the mental tubercle and is continuous with the anterior border of the ramus. The upper border of the ramus is thin and bounds a wide notch, the mandibular incisures, which transmits the masseteric nerve and vessels from the infratemporal fossa. F, Posterior view of the mandible. The mandibular canal runs from the mandibular foramen obliquely downward and forward in the ramus and then horizontally forward in the body. The mylohyoid line is the origin of the mylohyoid muscle. The lingula, the medial border of the mandibular foramen, is the attachment site of the sphenomandibular ligament. (Images courtesy of AL Rhoton, Jr.)