The infratemporal fossa (ITF) is bounded superiorly by the skull base, specifically the greater wing of the sphenoid, which contains foramen ovale. It is bordered posteriorly by the temporal bone, including the petrous portion of the carotid canal, anteriorly by the posterior wall of the maxillary sinus, laterally by the mandible, and medially by the pterygoid body and lateral pterygoid plate. In this video, we report a case of a rare, exclusively extradural, schwannoma originating from the third division of the trigeminal nerve with a widened foramen ovale at the skull base. The tumor filled the ITF and extended laterally just through the sigmoid notch of the mandible. The patient complained of left cheek and lower jaw numbness and intermittent left jaw spasms. The tumor was deemed appropriate for endoscopic resection. To access the ITF, left-sided endoscopic sinus surgery, a modified endoscopic Denker\u27s approach, and posterior nasal septectomy were first performed. A nasoseptal flap was also harvested in case an intraoperative cerebrospinal fluid (CSF) leak required repair. Dissection was carried out through the posterior wall of the maxillary sinus and pterygopalatine fossa to reach the ITF. Tumor resection was achieved through a 2-surgeon, 4-handed approach in which appropriate traction and countertraction were carefully applied to tease the tumor away from the skull base and dehiscent carotid canal. No CSF leak or carotid injury occurred, and the posterior maxillary sinus wall defect was repaired with the nasoseptal flap. The patient did well postoperatively. The patient consented to the procedure in a standard fashion
