 Parasympathetic fibers. The anatomy of the parasympathetic nervous system is more straightforward. There's a little bit of review. Do you remember? Okay, parasympathetic. What do you notice about my green fibers? Green fibers are coming from where, my friends? They're coming from the brain and they're coming from the sacrum. So S2 to S4 and cranial nerves. What? Cranial nerves? Who? What cranial nerves carry parasympathetic fibers? Three, to make your pupils constrict. Seven, oops, seven goes like that. Seven is seven, sure does. To make you salivate and cry, nine to make you salivate some more, and 10 wholly to do everything else. What cranial nerve was 10? That was the vagus nerve. And it comes down like this and goes everywhere. The vagus nerve does 75 to 80% of all of your parasympathetic innervation. It's actually carried in the vagus nerve, which is wildly fantastic. The rest of your cranial nerves carry some of it and then you've got some sacral nerves that are carrying some of it. And what is the anatomy? What is the spinal cord anatomy? It's not this. And it's not this. In fact, it'll be this except, what am I going to cross off? Who needs this? That's going to be in the sympathetic nervous system. We're not even, just pretend like that doesn't exist for parasympathetic. So if we were going to map this, map our dark green pathway, where is our pre-ganglionic cell body? It's in the same place as all of our other visceral motor. It's in either the lateral gray horn or like the lateral arena. I think technically in the sacral spinal cord, they don't call it a lateral gray horn, but they do have a lateral gray area. And then, of course, in the cranial nerves, the visceral motor fibers are coming out of the brain. So they're not going to have, we're not mapping it onto the spinal cord at all because it's coming out of brain. But in the sacral region, for the areas that do map, we've got this parasympathetic fiber that comes through just like everybody else, comes through the ventral, I mean the anterior root, the spinal nerve, out the anterior ramus. And then, remember, this guy is so long and this is my pre-ganglionic neuron. And it's still, let's just pretend, it actually doesn't go to the heart. It's the vagus nerve that goes to the heart, but we're just going to pretend because, you know, pretending is fun. And I'll change my color just slightly. We'll make it a little bit darker. This is my ganglionic neuron. With parasympathetic fibers, the ganglia, the ganglionic neurons are really short. They're often embedded in the wall of the effector itself. Again, the heart is innervated by the vagus nerve, so we're not going to see this coming out of the spinal cord. But we would see a pre-ganglionic neuron that's really long coming out of the brainstem where cranial nerve 11 exits the brain. I mean 10, because that's the vagus nerve. Oh, what's true about my pre-ganglionic neuron? Okay, I love you guys a lot and I really want to put the yellow ruffly pants on this pre-ganglionic neuron, but it's really long, really long. Look at me, I'm doing it anyway. Go! Okay, we have a little bit of wonkiness in my... Oh, look, I did it. It's totally myelinated. Is my ganglionic neuron myelinated? No, and that's the characteristic of my visceral motor pathways. What else do you need to know? It's going to calm us down, but to chill out we're going to be able to make babies unless we're sea urchins, but sea urchins don't have spinal cords, so we're cool, that's it. Are you happy? Okay, now we're going to review all of it together and I will be right back to do that.