The 12 cranial nerves are a set of nerves that originate in the brain and provide motor and sensory functions to the head and neck. Each cranial nerve has a different function responsible for sense or movement. They include:
- Olfactory nerve (CN I): essential for detecting smells.
- Optic nerve (CN II): enables a person to see.
- Oculomotor nerve (CN III): helps control eye movement and blinking.
- Trochlear nerve (CN IV): helps move the eyes up and down or back and forth.
- Trigeminal nerve (CN V): responsible for sensations in the face and cheeks, taste, and jaw movements.
- Abducens nerve (CN VI): helps move the eyes.
- Facial nerve (CN VII): controls facial expressions and sense of taste.
- Vestibulocochlear nerve (CN VIII): responsible for hearing and balance.
- Glossopharyngeal nerve (CN IX): responsible for taste, somatosensory information from the tongue, tonsil, pharynx, and controls some muscles used in swallowing.
- Vagus nerve (CN X): responsible for sensory, motor, and autonomic functions of viscera (glands, digestion, heart rate).
- Accessory nerve (CN XI): controls muscles used in head movement.
- Hypoglossal nerve (CN XII): controls muscles of the tongue.
The functions of the cranial nerves are sensory, motor, or both. Sensory cranial nerves help a person see, smell, and hear. Conversely, motor cranial nerves help control muscle movements in the head and neck. Doctors can identify neurological or psychiatric disorders by testing cranial nerve functions.
