Microsurgical anatomy of the infratemporal fossa as viewed laterally and superiorly.

Abstract

Benign tumors involving cavernous sinus, trigeminal nerve, and middle cranial fossa occasionally extend to the infratemporal fossa (ITF). In this study, we describe the microsurgical anatomy and dissection of the ITF, as viewed laterally and superiorly. We also describe a new bypass graft to the supraclinoid internal carotid artery using the internal maxillary artery (IMA), which is found in the ITF. Twelve cadaver specimens were used. Dissection required zygomatic arch osteotomy, downward displacement of the temporalis muscle, extensive subtemporal craniectomy, and mild elevation of the temporal lobe together with the dura. The anatomic relationships between the lateral and medial pterygoid muscles and the neurovascular bundle of the ITF are demonstrated. The neurovascular bundle contains the IMA, which runs horizontally, and the main branches of the mandibular nerve, which run vertically. The course and anatomic variations of the IMA and inferior alveolar, lingual, auriculotemporal, and buccal nerves are shown. The distal IMA was quite tortuous and, when the artery straightened, we were able to perform a tension-free in situ IMA graft to the supraclinoid carotid artery in 9 of 12 specimens. Knowledge of the anatomy of the ITF is a prerequisite for tumor resection in this area. The IMA may serve as a bypass graft to the supraclinoid internal carotid artery if the cavernous or petrous carotid artery is involved by tumor and needs to be sacrificed.