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Deep Dissection of the Left Infratemporal Fossa and Lateral Pharyngeal Wall

Surgical Correlation


Deep dissection of the left infratemporal fossa and lateral pharyngeal wall. The zygomatic arch and ramus of the mandible have been removed as have the lateral and medial pterygoid muscles. The lateral pterygoid plate (medial wall of the infratemporal fossa) is exposed. 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. These foramina are located in the roof of the infratemporal fossa. 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 chorda tympani nerve, a branch of the facial nerve, enters the infratemporal fossa through the petrotympanic fissure and joins the lingual nerve. It conveys the sense of taste from the anterior two-thirds of the tongue and preganglionic parasympathetic fibers to the submandibular ganglion. The nerve to mylohyoid is a small motor branch of the inferior alveolar nerve and supplies the mylohyoid and anterior digastric muscles. The maxillary artery, shown cut here, gives rise to several branches: middle meningeal, buccal, and inferior alveolar. 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 and posterior to the lateral pterygoid plate is the tensor veil palatini muscle. Posteromedial to it is the levator veli palatini muscle. Both are muscles of the soft palate. The levator veli palatini muscle passes over the superolateral border of the superior pharyngeal constrictor muscle (partially cut) to enter the nasopharynx. A trio of slender muscles arise from the styloid process: the stylohyoid courses with the posterior digastric and encloses its intermediate tendon, the styloglossus passes forward to attach to the posterolateral margin of the tongue, and the stylopharyngeus descends medially to enter the pharyngeal wall between the superior and middle constrictor muscles. The glossopharyngeal nerve wraps around the stylopharyngeus to provide motor innervation to this muscle as well as sensory supply to the mucosa of the oropharynx.  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 internal carotid artery is located medial to the vein. The facial artery arises from the external carotid and passes deep to the digastric muscle to enter the submandibular triangle where it gives rise to the submental branch to the floor of the mouth. 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.)