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We're going to talk about the cranial nerves.

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I'm going to start out with the first cranial nerve,

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the olfactory nerve,

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and begin with the olfactory mucosa.

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Now, here is the olfactory tract and bulb.

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As it starts to expand, as you come more anteriorly there,

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you can see it a little better because it's expanding,

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and it's going to communicate with the mucosa.

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Now, the olfactory epithelium is located in the anterior

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superior nasal concha, which is where we are.

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The conchae are up in here and take up about

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two and a half cubic centimeters.

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Inside the olfactory mucosa are olfactory cells,

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and they're peripheral receptors that transmit

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pulses to the olfactory neurons.

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There are about 6 million bipolar cells called Schultze's

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cells, and they're distributed inside the epithelium.

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Their dendrites are grouped together in filaments,

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which constitute the true olfactory nerve.

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And they cross the cribriform plate at the level

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of the ethmoid bone to reach this bulb.

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So there are little perforations here in the plate that

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allow the nerves of the mucosa here to communicate here.

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And when they get here, there's going to be a synapse.

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Now,

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if we just look at the olfactory bulb for a minute in

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the sagittal projection, so this would be anterior,

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this would be posterior.

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Coming from inside the brain are going to be several

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tracts. We're going to have a medial one.

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We have one that goes to the anterior commissure.

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We have an intermediate one.

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We're going to have a lateral sensory axon.

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And then these come back.

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And inside this bulb,

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these nerves are going to have a synapse.

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So I'll mark the synapse.

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There's a few of them.

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I'll mark the synapse with some other color.

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Let's go with red. So we've got a little synapse here.

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And then perforating, I'll use a different color,

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like blue.

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After the synapse perforating the cribriform plate.

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And then going into the nasal mucosa are

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going to be these neurosensory cells.

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And so the mucosa would kind of be here,

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bathed in these neurosensory cells,

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in the superior nasal concha.

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As I said,

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these neurosensory cells are called Schultze's cells.

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And this whole area,

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which I'll draw is kind of a big glob,

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even though it's a bunch of cells,

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6 million of them to be exact,

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is called the olfactory gland.

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So it's not really a single gland.

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It's kind of spread out in the olfactory mucosa.

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And then you go backwards, get a synapse.

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Then after the synapse,

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the nerve filaments run and run posteriorly to form these

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tracts inside the brain in the axial projection.

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So if we looked at where the tracts are,

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let's go back to our drawing of the olfactory mucosa.

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Here's the gyrus rectus. Here's,

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the medial olfactory gyrus, here's the sulcus in between.

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And we draw the bulb right here in blue.

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Then it comes back and then you'll have these

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bifurcations. One going laterally is the stria,

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one more intermediate and one going towards the anterior

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commissure. And we're going to add another one to that.

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That is going to go over to the Amygdala shortly.

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Let's move on. Pomeranz out.