Deep dissection of the left infratemporal fossa and proximal neck. The zygomatic arch and ramus of the mandible have been removed to expose the infratemporal fossa. The lateral and medial pterygoid muscles have also been removed. The mandibular branch of the trigeminal nerve emerges from the foramen ovale and the middle meningeal artery, a branch of the maxillary artery, ascends through the foramen spinosum. Several branches of the nerve can be seen here, including the roots of the auriculotemporal nerve (enclosing the middle meningeal artery), the buccal nerve, and the lingual and inferior alveolar nerves. The nerve to mylohyoid leaves the inferior alveolar nerve before that nerve enters the mandibular foramen and canal. It supplies motor innervation to the mylohyoid and anterior digastric muscles. The maxillary artery, shown cut here, gives rise to several branches: deep temporal arteries that ascend on the deep surface of the temporalis muscle in company with deep temporal nerves, middle meningeal, buccal, posterior superior alveolar, inferior alveolar, and artery to the lingual nerve. Distally, the maxillary artery enters the pterygopalatine fossa through the pterygomaxillary fissure and gives rise to the sphenopalatine artery, which supplies much of the nasal cavity. Deep to the medial pterygoid muscle (removed) is the styloglossus muscle. It arises from the anterior and lateral margins of the styloid process and inserts into the posterolateral margin of the tongue. The posterior superior alveolar nerve is a branch of the maxillary nerve and passes out of the pterygopalatine fossa through the pterygomaxillary fissure to small foramina on the posterior wall of the maxilla. It provides general sensory innervation to the maxillary sinus and maxillary molars. The external acoustic meatus lies just posterior to the mandibular fossa containing the head of the mandible. The internal jugular vein descends in the proximal neck deep to the posterior digastric muscle. On its external surface is the spinal accessory nerve. Anterior to the vein is the common carotid artery and its external carotid branch. The facial artery arises from the external carotid and passes deep to the digastric muscle to enter the submandibular triangle. The hypoglossal nerve descends in the neck and near the angle of the mandible takes an abrupt bend to course forward deep to the digastric muscle passing deep to the mylohyoid muscle to enter the floor of the mouth. At the bend of the hypoglossal nerve arises the superior root of the ansa cervicalis. It descends in the neck where it unites with the inferior root. The ansa cervicalis is part of the motor component of the cervical plexus and supplies motor innervation to the infrahyoid muscles. (Image courtesy of AL Rhoton, Jr.)