Endoscopic dissection of the Gasserian ganglion. Cranial nerve VI (abducens nerve) travels over the petrous apex to enter the cavernous sinus via Dorello’s canal with the inferior petrosal sinus. Cranial nerve V crosses the petrous apex to form the Gasserian ganglion, and subsequently divide into the three subdivisions: V1 (ophthalmic nerve), V2 (maxillary nerve) and V3 (mandibular nerve).