Infratemporal fossa and proximal neck dissection. The ramus of the mandible has been largely removed to expose contents of the infratemporal fossa. The superior and inferior heads of the lateral pterygoid muscle are shown as well as the medial pterygoid muscle. Emerging between these two muscles are the inferior alveolar nerve and lingual nerve. The former is coursing with the inferior alveolar artery (a branch of the maxillary artery) into the mandibular foramen to supply the mandible. The lingual nerve lies anteromedial to the inferior alveolar nerve and will enter the floor of the mouth to provide sensory innervation to the floor and anterior two-thirds of the tongue. The buccal nerve to the cheek wall emerges between the two heads of the lateral pterygoid. The distal portion of the external carotid artery is shown within the parotid bed and divides into its terminal branches, the maxillary and superficial temporal arteries. The maxillary artery passes behind the neck of the mandible to enter the infratemporal fossa. It usually courses superficial to the lateral pterygoid. The pterygoid venous plexus (removed) is also related to this muscle. This plexus consolidates laterally into short maxillary vein(s) that pass behind the mandible and unite with the superficial temporal vein to form the retromandibular vein. The stump of the facial nerve that gives rise to terminal branches within the parotid gland is in view. The infraorbital nerve and artery (branches, respectively, of the maxillary nerve and artery) are shown emerging from the infraorbital foramen. Similarly, the mental nerve and artery, branches of the inferior alveolar nerve and artery, are seen exiting the mental foramen. In the neck, the submandibular triangle is bounded by the two bellies (anterior and posterior) of the digastric muscle and lower border of the mandible. The mylohyoid muscle forms part of the floor of this triangle. The nerve to the mylohyoid, a branch of the inferior alveolar nerve, is seen coursing superficial to this muscle. It provides motor innervation to the mylohyoid and anterior digastric muscles. The hypoglossal nerve descends superficial to the external carotid artery and then bends forward deep to the digastric intermediate tendon to enter the oral cavity deep to the mylohyoid muscle. The external carotid artery is a branch off the common carotid artery. Lateral to this artery is the internal jugular vein. The spinal accessory nerve descends obliquely over the superficial aspect of the vein to enter and supply the sternocleidomastoid muscle (reflected). (Image courtesy of AL Rhoton, Jr.)