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Exposure of Lateral Brain, Left Infratemporal Fossa, and Retromandibular Area

Surgical Correlation


Exposure of lateral brain, left infratemporal fossa, and retromandibular area. The mandibular ramus, zygomatic arch, greater wing of sphenoid, and squamous portion of the temporal bone have been removed to expose part of the brain with overlying dura mater and the infratemporal fossa. 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. In this view, the inferior alveolar and lingual nerves are descending on the medial pterygoid after having emerged between it and the inferior head of the lateral pterygoid. Preganglionic parasympathetic fibers leave the lingual 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. Posterior to the ramus of the mandible (removed) is the external carotid and 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. The middle meningeal artery ascends and passes through the foramen spinosum. It appears to be giving rise to the accessory meningeal artery which ascends through the foramen ovale. The maxillary artery then passes 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. Deep to the mandible are the internal carotid artery and internal jugular vein. The cervical segment of the ICA continues into the carotid canal as the petrous segment while the internal jugular vein emerges from the nearby jugular foramen. Portions of the glossopharyngeal, vagus, and hypoglossal nerves are also in view. Lateral neck musculature has been removed to expose portions of two of the three suboccipital muscles, namely, the obliquus capitis inferior and superior. (Image courtesy of PA Rubino)