Cranial Nerves

Cranial nerves are simply the nerves that run into and out of the brain. You see, the spinal cord sends out spinal nerves to take care of the body. But if you look back at that dermatome image, you'll see that the spinal nerves cannot supply the head very well. And we have to see, taste, smell, hear, and detect our balance with senses located in the head, so all of that information has to enter our CNS somewhere. We also have to control the muscles of our face. And we have to perform some more involuntary functions, like pupil constriction, as well. All of these things have to work by sending information into and out of the brain directly. That's where cranial nerves come in.

Since you now know about all the regions of the brain, I think it is helpful to learn about all 12 cranial nerves by learning where in the brain they are found. Here's a table that shows this to you and gives you just about all the information you need to know for each cranial nerve:

Brain Region

CN#

Cranial Nerve Name

General Function of that cranial nerve

Telencephalon

I

Olfactory

Olfaction

Diencephalon

II

Optic

Vision

Midbrain

III

Oculomotor

Eye Movement (most of our eye movements are commanded through this nerve)

Pons

IV

Trochlear

Eye Movement (only one eyeball muscle, the trochlear muscle, is controlled through this nerve)

V

Trigeminal

Sensation of face and mouth

Mastication commands

VI

Abducens

Eye Movement (only one eyeball muscle, the lateral rectus muscle, is controlled through this nerve)

VII

Facial

Facial Muscle Contraction

Some Taste Sensation

Some Glandular Innervation runs through here, too

Medulla

(and spinal cord
for #XI)

VIII

Vestibulocochlear

(some say pontine)

Senses from our Ears:

	Hearing
	Balance

IX

Glossopharyngeal

Some Taste

Some Swallowing Muscles

X

Vagus

Involuntary Functions, it has a role in:

	Heart Rate
	Breathing Rate

Some Taste

Some Swallowing Muscles & Laryngeal Muscles

XI

Spinal Accessory

Some Laryngeal Muscles

Some Muscles of Back and Neck

XII

Hypoglossal

Movement of Tongue

How can you possibly remember these? Well, most students learn one or another mnemonic device to help them learn these. The one I learned is On Old Olympus' Towering Tops A Fin And German Viewed Some Hops. But this one is not a favorite among students. Also, for this one and the ones below, you have to use the old name for cranial nerve VIII, the Auditory nerve, rather than the vestibulocochlear nerve.

There was another one that was dirty that started with "oh, oh, oh...," but I never really learned it. So a couple of students made up a new mnemonic device last year, which was:

Oh, Oh, Oh, To Touch And Feel And Grip Vegas' Slot Handles. I like this one, because Vegas, short for Las Vegas, is the part of the mnemonic device that stands for the Vagus nerve.

or, you could try

Oh, Oh, Oh, To Touch And Feel A Girl's Very Soft Hair.

or, you could try

(to the tune of the carol "Partridge in a pear tree") Old Optic Oven, Three Tasty Apples, Four Very Good Veggies, and Huckleberries. I don't really like this last one, but maybe it works for you. I hope one of these helps you!

Just so you know, there are other functions of these nerves that are not listed above. Including the pupil constriction function I had mentioned at the top of the page. We will get to some of these unlisted functions later.

Also, we'll delve into more detail about the Vagus nerve next semester, but, just so you know, it is a vital nerve. We cannot live if anything happens to it.

Finally, your book lists whether each nerve is sensory, motor, or mixed in its table, Table 11.9. I haven't done that. But looking at that may help you to learn these.

For another website that goes through the cranial nerves and includes some online quizzes, check out this one at Gateway Community College in Phoenix, AZ.

� 2006 STCC Foundation Press
written by Dawn A. Tamarkin, Ph.D.