Kranialnervene

Kranialnervene, known in English as the cranial nerves, are twelve paired nerves that originate from the brain and brainstem and innervate structures in the head and neck. They carry sensory information, motor commands, and, for several nerves, autonomic fibers that regulate glands and some internal organs. The twelve nerves are numbered I through XII and named: I olfactory, II optic, III oculomotor, IV trochlear, V trigeminal, VI abducens, VII facial, VIII vestibulocochlear, IX glossopharyngeal, X vagus, XI accessory, and XII hypoglossal. Each nerve has characteristic functions: for example, I carries smell, II vision, III, IV, and VI control most eye movements, V provides facial sensation and chewing, VII governs facial expression and taste in the anterior tongue, VIII handles hearing and balance, IX and X contribute to taste, swallowing, and autonomic control, XI moves the neck and shoulders, and XII moves the tongue.

The nerves arise from the brain and brainstem and travel to their targets through various openings in the skull. They are routinely evaluated in clinical practice to detect deficits that may indicate injuries, tumors, stroke, or neurodegenerative conditions. Disorders of the cranial nerves can produce a wide range of symptoms, including vision changes, facial weakness, altered sensation, difficulty swallowing, hearing problems, or impaired autonomic functions. The study of kranialnervene encompasses anatomy, physiology, and clinical neurology, reflecting their central role in sensation, movement, and autonomic regulation of head and neck structures.