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I'm here to talk to you about the fifth nerve,

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or trigeminal nerve.

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Now, I could start in the brainstem with the real origin of

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the nerve, but that might drive you

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crazy because it's so complex.

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So I'm going to begin with the exterior exit of the

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nerve from the inferior aspect of the pons.

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You've got the nerve,

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which consists of a sensory and motor portion,

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then, a ganglion, and then three major divisions.

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Now, the lingual nerve, well,

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it took a swerve around the hyoglossus.

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"Well, I'll be plucked," said Wharton's Duct.

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"The lingual nerve has crossed us."

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That's one mnemonic for one branch of one division

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of the three divisions of the trigeminal nerve.

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Thus you see the challenge.

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The trigeminal nerve, well, it's a mixed nerve.

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Its sensory portio major portion, carries touch.

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Nociception.

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Temperature, proprioception from the face,

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the facial, the masticator muscles,

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the TMJ and the intraoral cavity.

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Somatosensory fibers of the trigeminal nerve enter the

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pons in the sensory root known as the portio major.

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They're distributed to a principal sensory nucleus and

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the spinal trigeminal nucleus.

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Fibers from the principal sensory nucleus

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and from the pars oralis and interpolaris of the spinal

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nucleus of the trigeminal nerve,

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which will show you decussate at the level of

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the pons and join the medial lemniscus,

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which is an important proprioceptive pathway as

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something known as the trigeminal lemniscus.

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And it terminates on the medial VPM or ventral

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posterior nucleus of the thalamus.

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There are also some uncrossed fibers.

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But the bottom line is you've got some fibers

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going over to the VPM.

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On one side,

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you've got some fibers going over to the VPM,

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the ventral posterior nucleus of the thalamus on the other side,

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so you've got projections to both sides.

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And then on both sides, they go up to S1,

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the primary somatosensory cortex of the brain.

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That's a lot of information,

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but we're going to drill into it a little more

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deeply on subsequent vigettes.

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Dr. P out.