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Dr. P here with the glossopharyngeal nerve,

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also known as the 9th cranial nerve.

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It's a mixed nerve that carries afferent sensory

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and efferent motor information.

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Now, it exits the brainstem from the

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sides of the upper medulla.

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And you can see that we're not at the upper medulla,

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we're at the level of the pons.

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And the reason is, I want to give you a landmark.

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Got the 7th and 8th nerve complex exiting anterolaterally.

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In front of that, we also happen to have,

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coincidentally, nerve six.

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And now we go down.

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And as we go down,

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if you can count from seven and eight,

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you're going to run into nerve number nine.

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And there it is.

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And with it, you have traveling some other nerves,

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ten and eleven, right behind it

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along the posterior aspect of the upper medulla.

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Now, for you wine lovers out there,

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and for you medical students and residents,

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the glossopharyngeal nerve participates in taste,

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along with the chorda tympani coming from the 7th nerve,

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which travels with the lingual nerve,

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which is part of the third division

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of the trigeminal nerve.

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So that gets the anterior two thirds

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of the tongue for taste,

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while the glossopharyngeal nerve gets

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the posterior one third.

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Now, the motor division of the glossopharyngeal nerve

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is derived from the basal plate of the

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embryonic medulla oblongata,

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while the sensory division originates

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from the cranial nerve crest.

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Now, let's have a look again at the apparent

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origin of the glossopharyngeal nerve.

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If we tack a little cursor right here,

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right there in the coronal projection,

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you can see with a slightly upward course in this individual,

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is the glossopharyngeal nerve,

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right there, just to the right of the brainstem,

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upper portion of a medulla.

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And there it is,

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coming right out of the medullary region,

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the apparent origin of the glossopharyngeal

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nerve, number nine.