[TA] the chief sensory nerve of the face and the motor nerve of the muscles of mastication; its nuclei are in the mesencephalon and in the pons and medulla oblongata extending down into the cervical portion of the spinal cord; it emerges by two roots, sensory and motor, from the lateral portion of the surface of the pons, and enters a cavity of the dura mater, the trigeminal cave, at the apex of the petrous portion of the temporal bone, where the sensory root expands to form the trigeminal ganglion; from there the three divisions (ophthalmic [CN V1], maxillary [CN V2], and mandibular [CN V3] nerves) arise. SYN: nervus trigeminus [CN V] [TA], fifth cranial nerve [CN V], trifacial nerve.