The trigeminal nerve supplies the skin of the face, thelips, the tooth pulp, the oral and nasal cavities, the mu-cosa of sinuses, the cornea, and the meninges. All thesestructures are often involved in pathological processescausing pain. Trigeminal afferents project by means ofthe trigeminal ganglion to the mesencephalic nucleus, theprincipal sensory nucleus (PSN), the interstitial nucleusof the spinal trigeminal tract (ISVT), and the spinal tri-geminal nucleus (STN).