MICROSURGICAL ANATOMY OF THE INFRATEMPORAL FOSSA AS VIEWED LATERALLY AND SUPERIORLY

OBJECTIVE: Benign tumors involving the cavernous sinus, trigeminal ner ve, 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 des cribe a new bypass graft to the supraclinoid internal carotid artery u sing the internal maxillary artery (IMA), which is found in the ITF. M ETHODS: Twelve cadaver specimens were used. Dissection required zygoma tic arch osteotomy, downward displacement of the temporalis muscle, ex tensive subtemporal craniectomy, and mild elevation of the temporal lo be together with the dura. RESULTS: The anatomic relationships between the lateral and medial pterygoid muscles and the neurovascular bundle of the ITF are demonstrated. The neurovascular bundle contains the IM A, which runs horizontally, and the main branches of the mandibular ne rve, which run vertically. The course and anatomic variations of the I MA and inferior alveolar, lingual, auriculotemporal, and buccal nerves are shown. The distal IMA was quite tortuous and, when the artery was straightened, we were able to perform a tension-free in situ IMA graf t to the supraclinoid carotid artery in 9 of 12 specimens. CONCLUSION: Knowledge of the anatomy of the ITF is a prerequisite for tumor resec tion in this area. The IMA may serve as a bypass graft to the supracli noid internal carotid artery is the cavernous or petrous carotid arter y is involved by tumor and needs to be sacrificed.