12 cranial nerves (diagram) (English)

The olfactory nerve (CN I) is solely sensory and conveys impulses that provide the sense of smell (olfaction). The optic nerve (CN II) is also a sensory nerve, responsible for vision. The oculomotor (CN III), trochlear (CN IV) and abducens (CN VI) nerves can be observed as a group due to their similar functions: all are motor nerves that innervate the eye muscles and thus play a key role in eye movement/accommodation. The trigeminal nerve (CN V) is the first mixed nerve (i.e. has both sensory and motor fibers). This nerve provides the sensation for the face and controls the muscles of mastication. The facial nerve (CN VII) is also a mixed nerve. The function of the sensory portion of this nerve is to provide a taste for the anterior portion of the tongue, while its motor component plays part in the modulation of facial expressions, salivation, and lacrimation. The vestibulocochlear nerve (CN VIII) is a sensory nerve in charge of maintaining balance and hearing. The glossopharyngeal nerve (CN IX) is a mixed nerve that provides sensation to the tongue and pharynx, as well as the control of muscles that facilitate the act of swallowing. The vagus nerve (CN X) is the longest mixed cranial nerve. Its sensory role is to convey sensory information from the external ear, pharynx, larynx, thorax, and abdomen. In contrast, its motor component plays part in acts of swallowing, speech, coughing, and various parasympathetic functions. The accessory nerve (XI) is solely a motor nerve. It controls two muscles involved in head and shoulder movements (sternocleidomastoid and trapezius muscles). The hypoglossal nerve (CN XII) is also a motor nerve that controls muscles that facilitate the movements of the tongue.