cranial nerves [Gk, kranion, skull; L, nervus] , the 12 pairs of nerves emerging from the cranial cavity through various openings in the skull. Beginning with the most anterior, they are designated by Roman numerals and named (I) olfactory, (II) optic, (III) oculomotor, (IV) trochlear, (V) trigeminal, (VI) abducens, (VII) facial, (VIII) vestibulocochlear (acoustic), (IX) glossopharyngeal, (X) vagal, (XI) accessory, and (XII) hypoglossal. The cranial nerves originate in the base of the brain and carry impulses for such functions as smell, vision, ocular movement, pupil contraction, muscular sensibility, general sensibility, mastication, facial expression, glandular secretion, taste, cutaneous sensibility, hearing, equilibrium, swallowing, phonation, tongue movement, head movement, and shoulder movement. Certain cranial nerves, particularly V, VII, and VIII, contain two or more distinct functional components considered as independent nerves by some authorities. Some anatomists also classify the terminal nerve as the first cranial. Also called cerebral nerves.
