Cranial nerves

So I want to talk about a thing called the oculocardiac reflex, something we see not too infrequently here.

And what it is, it's this kind of cool phenomenon where it's this two nerve reflex where you get some sort of eye trauma and you get pressure on the ophthalmic branch of the trigeminal nerve.

That's cranial nerve five.

It goes back to your brainstem and then the reflex arc sends a signal out through the vagus nerve to your heart, and this is a parasympathetic kind of rest and digest signal that slows your heart rate down.

Instead, they run right from the brain, almost all the way to their effectors.

There are 12 of these cranial nerves, and they vary in terms of what kinds of neurons they contain.

I mean, we're talking about the autonomic system here, but they are not all autonomic motor fibers.

Some of your cranial nerves also carry motor fibers that control voluntary functions, like moving your eyeballs around.

And others carry only sensory fibers, which relay data to and from your sensory organs.

And, you know, just to keep things interesting, some of your cranial nerves carry both motor and sensory neurons.

So, which ones are where, and what exactly does each one of these 12 nerves do? As anatomists, we have to keep track of the human wiring diagram that are cranial nerves, because you don't want to end up like some sidekick in a 90s action movie who has to defuse a bomb all by himself.

the red wire or the black wire? Honestly though, if you find yourself inside of somebody's brain stem, you probably shouldn't be cutting anything.