Deep dissection view of the left infratemporal fossa and proximal neck. The mandibular ramus, zygomatic arch, greater wing of sphenoid, and squamous portion of the temporal bone have been removed. The infratemporal fossa is exposed and both heads of the lateral pterygoid muscle have been removed. The bulk of the medial pterygoid muscle (deep portion) arises from the medial surface of the lateral pterygoid plate. The superficial portion arises from the maxillary tuberosity. The medial pterygoid inserts into the medial surface (below the level of the mandibular foramen) and angle of the ramus of the mandible. Laying on its surface are the inferior alveolar and lingual nerves. Preganglionic parasympathetic fibers leave the latter nerve to travel to the submandibular ganglion. The buccinator muscle attaches to the alveolar process of the upper and lower jaws in the molar regions before entering the lips. The external carotid divides into its terminal branches, the maxillary and superficial temporal arteries near the neck of the mandible. The maxillary artery enters the infratemporal fossa by passing between the neck of the mandible and the sphenomandibular ligament (first or mandibular part of the maxillary artery). This segment typically gives rise to the deep auricular, anterior tympanic, inferior alveolar, middle meningeal, and accessory meningeal arteries. It then passes deep (but usually superficial) to the inferior head of the lateral pterygoid muscle as the second or pterygoid part where it gives rise to the buccal, pterygoid, masseteric, and deep temporal branches. The third or pterygopalatine part lies anterior to the lateral pterygoid before it passes through the pterygomaxillary fissure into the pterygopalatine fossa. Branches of this third part appear deep within the infratemporal fossa, including the posterior superior alveolar arteries and the infraorbital artery to the orbital floor via the inferior orbital fissure. The remaining descending palatine, sphenopalatine, and pharyngeal arteries are found within the pterygopalatine fossa. The buccal and auriculotemporal nerves are visible where the lateral pterygoid muscle once was. The inferior alveolar artery (cut) accompanies the inferior alveolar nerve into the mandibular canal. The mylohyoid artery, a branch of the inferior alveolar crosses the medial pterygoid to course toward the mylohyoid muscle. Near the angle of the mandible (removed) are branches of the external and internal carotid arteries and the internal jugular vein. A portion of the styloglossus muscle can be seen passing forward toward the superolateral edge of the tongue. The hypoglossal nerve wraps around the root of the occipital artery and courses forward to the oral cavity superficial to the hyoglossus muscle then deep to the mylohyoid muscle. It provides motor innervation to the extrinsic and intrinsic muscles of the tongue, except palatopharyngeus.