Cranial nerves

Twelve pairs of nerves that emerge directly from the underside of the brain. Each of the nerves has a number as well as a name. The numbers indicate the sequence in which the nerves emerge from the brain. The main function of some cranial nerves is to deliver sensory information from the ears, nose, and eyes to the brain. These are the vestibulocochlear nerve (hearing and balance), olfactory nerve (smell), and optic nerve (vision). Other cranial nerves carry impulses that move muscles of the head and neck area. These are the oculomotor, trochlear, and abducent nerves (movements of the eye), spinal accessory nerve (head and shoulder movements), and hypoglossal nerve (tongue movements). Some cranial nerves have both sensory and motor functions. These are the facial nerve (facial expressions, taste, and the secretion of saliva and tears) trigeminal nerve (facial sensation and jaw movements) and glossopharyngeal nerve (taste and swallowing movements). The vagus nerve has branches to all the main digestive organs, the heart, and the lungs, and is a major component of the parasympathetic nervous system, which is concerned with maintaining the body’s automatic functions. All but 2 of the cranial nerve pairs connect with nuclei in the brainstem (the olfactory and optic nerves link directly with parts of the cerebrum). The nerves emerge through openings in the cranium; many then soon divide into branches.