Inferior View of a Stepwise Dissection of an Axial Section of the Cranial Base. A, The internal carotid artery is located behind the infratemporal fossa in the posterior part of the parapharyngeal space lateral to the longus capitis muscle. The infratemporal fossa is surrounded by the maxillary sinus anteriorly, the mandible laterally, the pterygoid process anteromedially, and the parapharyngeal space posteromedially. The infratemporal fossa contains the mandibular nerve and the maxillary artery and their branches, the medial and lateral pterygoid muscles, and the pterygoid venous plexus. B, The deep head of the medial pterygoid muscle and the upper head of the lateral pterygoid muscle have been removed to expose the lateral pterygoid plate and lower surface of the greater wing of the sphenoid adjacent to the foramen ovale. The tensor and levator veli palatini have been exposed below their attachment along the margins of the eustachian tube. C, The tensor and levator palatini have been removed to expose the cartilaginous and fibrous parts of the eustachian tube. The accessory meningeal branch of the maxillary artery passes through the foramen ovale and supplies the branches of the third trigeminal division and the tensor veli palatini. D, The medial part of the fibrous and cartilaginous parts of the eustachian tube have been removed to expose the petrous apex and foramen lacerum. The mucosa has been removed from the roof of the nasal cavity to expose the processus tubarius of the body of the sphenoid bone. Fibrocartilaginous tissue fills the foramen lacerum. The petrosphenoid sulcus extends along the junction of the petrous apex and greater wing of the sphenoid. (Images courtesy of AL Rhoton, Jr.)