Cranial Nerves

Cranial nerves exit the inferior region of the cranium through foramina in the cranial bones and are numbered I–XII.
There are 12 pairs of cranial nerves emerging from the brain. Unlike other nerves that travel throughout the entire body, the cranial nerves are located only in the head and neck regions. Cranial nerves can be sensory (carry sensory information to the brain), motor (carry motor information away from the brain), or mixed (carry both types of information).Cranial nerves are numbered I–XII (using Roman numerals), and their names describe either what they do or the structures they serve. Cranial nerve I is located closest to the frontal lobe, while cranial nerve XII is found closest to the brain stem.

Locations of the Cranial Nerves

The 12 pairs of cranial nerves each serve different areas of the head and neck regions. These may include eye movements, hearing, changing facial expressions, or swallowing.

Name and Function of Cranial Nerves

Number Name Function
I Olfactory nerves These nerves help produce the sense of smell.
II Optic nerves These nerves transmit visual information from the retina of the eye to the brain.
III Oculomotor nerves These nerves control the movement of the eye muscles, focusing of the eyes, and constricting of the pupils.
IV Trochlear nerves These nerves work with the oculomotor nerves to help move the eye in different directions.
V Trigeminal These nerves extend from the pons to the face and assist with the sensations of touch, temperature, and pain. They transmit information to the skin of the head, the eyelids, nose, teeth, lids, and inside of the mouth.
VI Abducens These nerves come from the pons and help with eye movement.
VII Facial These nerves also arise from the pons and then innervate the face. They help send signals that stimulate chewing, saliva production, and the taste buds.
VIII Vestibulocochlear These nerves come from the cochlea and vestibule (the parts of the ear that control hearing and balance) in the inner ear. They assist the body in maintaining equilibrium and also help with hearing.
IX Glossopharyngeal These nerves come from the medulla oblongata and leave the skull to innervate the throat area. They help with the movement of the throat and tongue muscles, allowing for swallowing to occur. They also help with the production of taste and the feelings of touch, pressure, and pain in the throat area.
X Vagus These nerves arise from the medulla oblongata and travel to areas of the body below the head and neck region. They help provide signals to the heart, lungs, and abdominal cavity. They also carry signals to and from the skin, the taste buds, and the muscles of the larynx and pharynx.
XI Accessory These nerves are unique in that they arise from the spinal cord, not the brain stem. They enter the skull at its base and travel with the vagus nerves to innervate two large neck muscles. They assist with motor functions of the trapezius and sternocleidomastoid muscles of the head and neck.
XII Hypoglossal These nerves come from the medulla oblongata and innervate the tongue. They allow for movements of the tongue when chewing and swallowing. They also assist with speech.

Cranial nerves are named based on their structure or function. For example, the olfactory nerve (I) relays smell, while the facial nerve (VII) relays motor functions to the face. The cranial nerves are numbered in order from front to back within the brain.