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The 12 Cranial Nerves

Contents

There are twelve Cranial Nerves that supply the head, neck and internal organs. Here you can find a structured list of the nerves in numerical order, which includes their position, exit from the skull, what each nerve supplies and whether it is a motor or sensory nerve.

Cranial Nerve I: The Olfactory Nerve Stemming from the left and right olfactory bulbs, exiting the Skull through the cribriform plate and terminating in the roof of the nasal cavity, this nerve governs the olfactory nerve fibers which register smell.

Cranial Nerve II: The Optic Nerve Stemming on the left and right side from the optic chiasm, exiting the skull through the optic canal and terminating in the eye, this nerve governs the ocular and sensory functions.

Cranial Nerve III: The Oculomotor Nerve Stemming from the mesial superior margin of the left and right side of the pons, exiting the skull through the superior orbital fissure and terminating in the muscles of the eye: ciliary, sphincter pupillae and all the external eye muscles except: superior oblique and lateral rectus. This nerve motorically innervates the previously mentioned eye muscles and allows the eye to move within the orbit.

Cranial Nerve IV: The Trochlear Nerve Stemming from the lateral superior margin of the left and right side of the pons, exiting the skull through the superior orbital fissure and terminating in the superior oblique eye muscle, this nerve motorically governs the abduction, depression and internal rotation of the eye.

Cranial Nerve V: The Trigeminal Nerve Stemming from the lateral superior margin of the left and right side of the pons, this nerve branches into three: V/I ophthalmic, V/II maxillary and V/III mandibular nerves. These branches exit the skull through the superior orbital fissure (V/I), the foramen rotundum (V/II) and the foramen ovale (V/III). This nerve governs the sensory innervation of the face, sinuses and teeth.

Cranial Nerve VI: The Abducent Nerve Stemming from the medial inferior margin of the left and right side of the pons and the left and right pyramids, this nerve exits the skull via the superior orbital fissure and innervates the lateral rectus muscle of the eye, which retracts the eye within the orbit.

Cranial Nerve VII: The Facial Nerve Stemming from the lateral inferior margin of the left and right side of the pons and the left and right olives, this nerve exits the skull through the Internal acoustic meatus. It supplies the muscles of the face with motoric fibers and taste sensation to the anterior two thirds of the tongue.

Cranial Nerve VIII: The Vestibulocochlear Nerve Stemming from the lateral inferior margin of the left and right side of the pons and the cerebellum, exiting the skull via the internal acoustic meatus, this single nerve contains both vestibular and cochlear fibers. The cochlear fibers terminate in the cochlea and the vestibular fibers terminate in the ampullae of the vestibulum. They supply sensory innervation to the inner ear.

Cranial Nerve IX: The Glossopharyngeal Nerve Stemming from between the olives and the cerebellum, this nerve exits the skull via the jugular foramen. It provides taste sensation for the posterior third of the Tongue, sensation to the tonsils, pharynx and middle ear and motoric fibers to the stylopharyngeus muscle and the parotid gland.

Cranial Nerve X: The Vagus Nerve Stemming from between the olives and the cerebellum, this nerve exits the skull via the jugular foramen. It motorically innervates the heart, lungs, palate, pharynx, larynx, trachea, bronchi and gastrointestinal tract. It provides sensation to the heart, lungs, trachea, bronchi, larynx, pharynx, gastrointestinal tract and the external ear.

Cranial Nerve XI: The Accessory Nerve Stemming from between the cuneate fasciculus and lateral funiculus and exiting the skull via the jugular foramen, this nerve motorically innervates the Sternocleidomastoid muscles and Trapezius muscles.

Cranial Nerve XII: The Hypoglossal Nerve Stemming from between the gracile and cuneate fasciculus, this nerve exits the skull via the hypoglossal canal. It motorically innervates the muscles of the tongue, except the palatoglossus, which is innervated by the vagus nerve (CN X). It also gives C1-3 fibers to the strap muscles (infrahyoid muscles).

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Show references

Reference:

  • Frank H. Netter (urban and Fischer), Atlas of Human Anatomy, 4th Edition, Saunders, 2006, Plates 12 and 13.

Author:

  • Dr. Alexandra Sierosławska

Illustrators:

  • Cranial nerves - Yousun Koh 
© Unless stated otherwise, all content, including illustrations are exclusive property of Kenhub GmbH, and are protected by German and international copyright laws. All rights reserved.

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