The trigeminal nerve is the largest of the cranial nerves. It has both sensory and motor functions. It has three main divisions: the ophthalmic, maxillary, and mandibular nerves. The ophthalmic nerve innervates the eye and forehead. The maxillary nerve supplies sensation to the cheek, upper teeth, and nose. The mandibular nerve provides motor input to the muscles of mastication and sensation to the lower face, teeth, and chin.