DIP Episode 89 - USMLE Step 1 Neuro Review 2

Okay, welcome to the 89th episode of the Divine Intervention Podcasts. My name is Divine. I'm a PGOI-1 transitional year resident going into radiology. And into these podcasts we're going to be continuing our discussion of Neural for step one. So this will be the second part in the series. This podcast will be mainly a teaching podcast. I mean, I will introduce some case scenarios along the way, but it will mostly be a teaching podcast because I want to use this podcast to lay a foundation for many questions. I'll be able to create in the future for the other on your podcasts. So let's begin. And really today, I'm just really going to spend a lot of time talking about the autonomic nervous system. Right? And in the autonomic nervous system, we already know it's divided into the sympathetic and parasympathetic systems. Right? And many of you have learned that, oh, it's a two neuron system. And really, it is a two neuron system. That's what you should remember for you example. The truth is, if you really want to get down and dirty, your autonomic nervous system is actually a three neuron system. So those two neurons, there's actually a neuron that comes before it in the hypothalamus. The hypothalamus is ultimately the origin of your autonomic nervous system. I'll talk about that in a future podcast and sort of make some references to that today. So your autonomic nervous system, what does it do? Basically, controls like smooth muscle, not skeletal muscle.

Skeletal muscle is mostly under the control of your like your somatic nervous system. But your smooth muscle, your cardiac muscle, for example, your glands, like your sweat glands, for example, those are all under the control of your autonomic nervous system. And like I said, right? We have the sympathetic and parasympathetic systems. And I mean, again, if you're going with a classic mantra of the two neuron system, we have like a pre-ganglionic neuron. Basically, between those two neurons, the pre-ganglionic and post-ganglionic, right? You can see pre-ganglion prior to ganglion, post-ganglion after ganglion. So that means a ganglion must sort of like being the way, right? Between pre-ganglionic and post-ganglionic. And the thing is, those pre-ganglionic neurons, right? They all arise from neuro tube because the acel bodies are all found in the central nervous system, right? Like, I mean, like for example, you classically, you people say that, oh, your, your, or you know what? Instead of doing that to confuse you even further, just, just believe what I say that the pre-ganglionic, because I will have to go from this huge tangent if I want to explain some other stuff. But let's just say that the pre-ganglionic neurons, the acel bodies are all in the central nervous system. So guess what? They all derive from neuro tube, okay? But the post-ganglionic neurons, right? The acel bodies actually found outside the central nervous system in ganglia, okay?

So because the acel bodies are found in ganglia, guess what? Those things actually derive from neuro crest, okay? So very high yield to know this. Your post-ganglionic, or the non-micro system neurons are all derived from neuro crest. In fact, if you look at the Adrenal Medulla, right? Remember I said in the earlier podcast that the Adrenal Medulla is modified post-ganglionic sympathetic neuroganglion basically. So those chromafin cells, so the Adrenal Medulla, right? They actually all derive from neuro crest. In fact, a very nice way they can test that is to test the fiochromocyte tumor. It's so like a patient presenting with like episodic headache and hypertension. And then they tell you like what's the embryologic origin of the cells that play a role in this disorder, right? Those will be on neuro crest cells, okay? Your Adrenal Medullary chromafin cells. Remember the Adrenal Medulla is very different from biologically from the Adrenal Cortex. And if you want to look at all the pre-ganglionic neurons as a whole, right? Basically all of them secret acetylcholine, okay? So the pre-ganglionic neurons, the squared-out acetylcholine, that acetylcholine acts on receptors that we find on the surface of the post-ganglionic neurons, okay? And acetylcholine receptors specifically that we find on the surfaces of post-ganglionic neurons and nicotinic acetylcholine receptors, okay?

So acetylcholine released by the pre-ganglionic neuron acts on the nicotinic acetylcholine receptors that are found on the post-ganglionic neurons, okay? And then those post-ganglionic neurons fire and then go all this fun stuff, okay? But one key thing you want to keep at the back of your mind is that those post-ganglionic neurons, depending on if you're talking about the sympathetic nervous system or the parasympathetic nervous system, they do totally different things, right? So for example, for a parasympathetic nervous system, the post-ganglionic neurons actually release acetylcholine as well, okay? They release acetylcholine, but the thing is the target organ, right? So like the target smooth muscle, the target cardiac muscle, the target glands that receive that innervation, okay? They actually have most corenic acetylcholine receptors on their surfaces, okay? So parasympathetic nervous system, post-ganglionic neuron, secrets acetylcholine acts on most corenic acetylcholine receptors that we find in the target organs. But in the sympathetic system, we actually have two variations on that thing, right? So they actually parts of the sympathetic nervous system that we have the post-ganglionic neurons release acetylcholine to act on target organ most corenic receptors. The big one you want to know for you exam is sweat glands, right? Your sweat glands actually do not receive parasympathetic innervation, okay?

Your sweat glands primarily receive sympathetic innervation, okay? And that post-ganglionic sympathetic neuron secrets acetylcholine to act on most corenic receptors on the surfaces of the sweat glands, okay? But the remaining adrenergic neurons, right? So the post-ganglionic sympathetic neurons, many of them secretive cadecolamine, right? So like noripinephrine, an epinephrine, okay? To act on target adrenergic receptors, which include alpha receptors, beta receptors, and whatnot. And again, don't forget, your adrenomadol is a modified post-ganglionic sympathetic neuron, okay? So those cells also have nicotinic acetylcholine receptors on their surfaces, right? So again, I would highly recommend you know those. I mean, I just talked earlier, I mentioned skeletal muscle and your somatic nervous system. The thing is skeletal muscle, right? It's more of a one neuron system. Again, everyone calls it a one neuron system. And that's what you should remember for your example. Again, that is not exactly true, right? Because if you really think about it, right? Those neurons, right? Those alpha-modon neurons that you find in the ventral horn of the spinal cord, right? Yeah, it's one neuron that goes through your muscular junction and they release a synocholine that acts on nicotinic receptors on the surfaces of skeletal muscle.

And actually notes that those nicotinic receptors are actually different from the nicotinic receptors we find on the surfaces of the post-ganglionic autonomic nervous system neurons. But the thing is those alpha-modon neurons of the ventral horn of the spinal cord, they actually also receive innervation from the corticospinal tract, right? And an upper-modon neuron that comes from the corticospinal tract. If you want to be a little more specific, that'll be the pre-central gyres of the of the of the cerebral cortex. So let's sort of talk about these branches a little more, right? So I guess we can talk about the past and pathetic nervous system first, right? So past and pathetic, you've probably heard of this boss phrase, cranial sacral, that oh, it has cranial sacral outflow, blab, blab, blab, blab. What do they mean by that? The things they mean by that are that certain cranial nerves, right? Actually constitute a part of your past and they carry like some past and pathetic nervous system fibers, okay? And then certain sacral spinal nerves also carry past and pathetic nerve fibers, right? So, and actually again, just make sure that everything is clear to you here. These cranial nerves and these sacral spinal nerves, okay? We're basically discussing them as post-gangrionic, past and pathetic neurons, okay? So all these things are all derived from guess what? Neural crest, okay? Very high yield to know that. So like cranial nerves, 379 and 10, okay?

Those all carry past and pathetic nerve fibers. And then your sacral spinal nerves, 204, okay? Carry, past and pathetic nerve fibers as well. So cranial nerve three, right? I mean like if you want to construct your poop ill, to have meiosis, or you want to sort of like adjust your, the shape of your lens with your ciliary muscles, those are all under the purview of cranial threes, past and pathetic functions. If you're looking at cranial sevens, past and pathetic functions, right? So like your, the glands that help you mix the livers, so like your sublingual glands, your sub mandible glands, your, even the glands in the, in your nasal mucus, right? And also the glands that make you cry, your lacrimal glands, let's think more tears of joy, I guess, than tears of sorrow. So the glands that make you have tears of joy, your lacrimal glands, they all under the control of the past and pathetic functions of cranial nerve seven. And then if you're looking at cranial nerve nine, it really doesn't do much in past and pathetic territory. The big one you want to remember for step one, you add the parodied glands, the parodied glands actually, innervate, actually innervated by cranial nerve nine, okay? The gloss of our ingenial nerve. And then cranial ten does pretty much every other thing. It's a wondering nerve, does pretty much every other thing all the way to your, to the splinic flesh. Okay, that's like in the left upper quadrant.

Remember, vagus nerve again, outside of the face, the vagus nerve does pretty much every parodied, then up until the splinic fracture. If you want to parse empathetically in your video hangout, and like your bladder, right? So and also like sort of like control, like your action, remember your parodied, synthetic system actually controls your action. That's where the secret part of the cranial secret outflow of your parodied synthetic system comes into place, so S2 to S4, okay? That's where they come in. And I mean, like I said, all these neurons, right? All these cranial three, seven, nine, ten and whatnot, they are all derived from neurocrest. And remember the neurocrest, for eight to accomplish its objectives, as I discussed in the first part of this series, I said that those neurons have to migrate, right? If they don't migrate, right? You can get into a lot of trouble, right? For example, Down syndrome is really just a neurocrest cell migration problem, right? So for example, Down syndrome is actually a hersperons disease, right? In hersperons disease, you don't have, you basically don't have neurons, right? In the ganglia, that constitute, especially like in the rectum or like your lower, like colon, right? So that's how the person gets into trouble, right? That's those neurons in those ganglia, they are derived from neurocrest cells. So if the neurocrest cells don't migrate well, they're getting into trouble.

If you look at the endocardial cushion defects that are company Down syndrome, right? Those endocardial cushions, the aortic opulmonary septum and whatnot, what do you think they are all derived from? Guess what? They are all derived from neurocrest. So again, if you have neurocrest cell migration problems, you can get cardiac problems. So one thing I'll just say is the disparate series of symptoms, you seem to observe in people that have Down syndrome. Those things actually explain if you just sort of think about the different things that are derived from neurocrest, right? And then ask yourself, oh, if this person's neurocrest cells don't migrate well, what can happen? Okay? And then many of the findings in Down syndrome will begin to make a little more sense to you. So your parasympathetic system, cranial sacral, right? So what's the bus freeze for the sympathetic nervous system, right? That's that's a thoracolomba, right? So thoracolomba outflow, a thoracol, the thoracol part is like T1 to T12 and then the lomba part is L1 to L2. And the thing is your sympathetic nervous system for the most part has shock pre-ganglionic neurons and long post-ganglionic neurons versus your parasympathetic system that has long pre-ganglionic neurons and short post-ganglionic neurons. The easy way to remember that is to remember one part of it, right? If you just remember what obtains for one part of the autonomic nervous system, the other one, you just know it's the other one, right?

So I give you an example, right? So one way I remember this is I remember that the sympathetic nervous system for some bizarre reason loves to deal with parasympathetic ganglia. Okay? Parasympathetic ganglia. So let's deconstruct that term parasympathetic ganglia. Parasympathetic ganglia means literally next to the vertebral bodies. Okay? Those sympathetic chain ganglia, they also known as parasympathetic ganglia. So think about it. If your sympathetic nervous system is to a colombar outflow and the pre-ganglionic neuron is studying in the spinal cord from T1 to T12 or L1 to L2 and just has to travel to a ganglion that is right next to the spinal cord that is right next to the vertebral bodies, it won't have to travel along this tense, right? If you remember that one fact, you can then basically create the rest of the information. I mean, I think I may have mentioned this in one of my prior, like how to study sort of a deal podcast, but basically try to learn the list amount of information that will allow you to control the most amount of information. That is how smart people learn, right? So if you remember that parasympathetic ganglia, you know that okay, well that means the pre-ganglionic neuron in the sympathetic nervous system does not have to travel that far, so it has to be short. And then from that you can deduce that okay, that means the post-ganglionic neuron has to travel along this tense, so it has to be long.

And then if you know that a parasympathetic nervous system is basically the opposite of the sympathetic nervous system, you can basically take opposites of everything. And boom, you remember all that that people make flush cards and all that crap to try to remember. So we have those parasympathetic ganglia, they are basically like they essentially have a lot of post-ganglionic sympathetic cell bodies that ultimately go to like sweat glands in the body and all that stuff. Okay, and let's see, actually one of the high-youthen I think I want to mention with your sympathetic nervous system is this thing known as the superior cervical ganglia, right? So the thing is your sympathetic nervous system, right? I basically think of it as doing two sets of things. It does your body and your face slash head. Okay, so your body is done primarily by the parasympathetic ganglia based post-ganglionic sympathetic neurons. But your face and your head okay, done mostly by your superior cervical ganglion based post-ganglionic sympathetic neurons. So what do I mean by that? So let me sort of talk through this, right? So I said that your sympathetic nervous system is for raccolon bar outflow, right? So the thing is your T1 spinal nerves, okay, your T1 spinal nerves basically can have some pre-ganglionic sympathetic neurons that ascend and go all the way to the superior cervical ganglia that's found in the neck, okay?

And then from the superior cervical ganglion we have post-ganglionic sympathetic neurons that then go and accomplish many things in the head and neck. I mean, I can give you some examples, right? So for example, some smooth muscles in the eye, right? So like your dilute up, up the leg muscles, right? So remember, if you're running from a lion, you don't want to like squint your eyes. I mean, if you squint your eyes, I mean, maybe the next time you open it up, you'll be in the belly of the lion, right? It's probably not an ideal outcome. But if you're running away from a lion, your eyes have to be like wide open, right? So your eyes have to be wide open and your eyelids have to be elevated as much as possible. So for your eyelids to be wide open, you need popularly dilators to make that happen. And if you want your eyelids to be wide open, you need something that elevates the eyelid, okay? And if you want to be a little more specific, that is your superior tassel muscle. Your superior tassel muscle is an elevator of the eyelid, okay? So it helps you elevate your eyelid so that you can run away from said lion. Although something that's kind of like a weird thing there is your levator popper brace superiorist, your LPS muscle, it's actually an elevator of your eyelid as well. But it's actually not innovative by your parasympathetic nervous system, but it's actually innovative by crinion of three. So people may say, come on, divine, what are you saying?

This is not making any sense. Remember that crinion of three has parasympathetic functions, but it also has its own somatic functions. One of the somatic functions of crinion three, the ocular motor nerve, is to innovate the levator popper brace superiorist, which also elevates your eyelid, okay? But crinion three has parasympathetic functions that include like your publicary constrictors and your silery muscles, your silery muscles that help you adjust the shape of the lens for accommodation. So your popularity dilators, superior tassel muscles, right? Those are all innovated by post-gongluring sympathetic neurons in my knee teen from the superior cervical ganglia. The thing is, from the superior cervical ganglia, a person can basically have those post-gongluring sympathetic neurons that take the circuitous course through the brain. So it's actually kind of high to know that they actually encircle the internal corroded arteries on their way to structures in the face. Because if you really think about it, if a person has like a corroded dissection, right, where classically they were presenting an exam as a person that went to a chiropractor for like a neck massage or a person that was like maybe brushing their teeth fast-fuly, fast-fuly. And then they have a dissection of the corroded arteries that can actually involve the fibers that are emanating from the superior cervical ganglia. And the person will basically have a hunger syndrome, right? So they will have toses, right?

So they'll have a droopy eyelid because the superior tassel muscle is not working. They will have meiosis because the pupillary constrictors will be working on a post because the pupillary dilators are no longer working. And they will have anhydrosis because remember I said that your sympathetic nervous system, some of the post-gongluring sympathetic neurons, release acetylcholine that acts on muscarinic receptors on sweat glands, okay? If you have lesions of those post-gonglionic sympathetic neurons, guess what? You will not release acetylcholine. And that, since you are not releasing acetylcholine, there's nothing to activate to the muscarinic receptors that you find on the surfaces of your sweat glands in the face. So the person will have anhydrosis, okay? So that's essentially the path of physiology behind the tussis, meiosis, and anhydrosis that is observed in hunger's syndrome. And it's actually very high yield to know that hunger's syndrome is usually, in fact, I'll say on MDM is it's always Ipsilateral, okay? It is always Ipsilateral to where you have the problem. So that is one potential cause of a hunger syndrome, right? So if you have lesion, like a dissection of the corroded arteries, another thing that can cause a hunger syndrome, right, can be like something called like a cervical rib, right? So most of your ribs, emanue from like your, for the most part, come from your thoracic vertebra, right?

But if for some bizarre reason you have a rib that comes from one of your cervical vertebra, that's very high up, right? That can potentially pierce the fibers that are on the way to the superior cervical ganglion, okay? And that can cause a hunger syndrome as well. Well, that'll be more of a pre-gonglionic sympathetic nerve defect. Another classic cause of a hunger syndrome, right? Again, I'm just basically trying to give you all the different ways you can test hunger syndrome on your exam. If a person has a pancus tumor, right, that's also called like a superior socus tumor. So it's like a tumor that you find in the upper, like, very high up in the lung. That can also compress the pre-gonglionic sympathetic nerve fibers that are going to the superior cervical ganglion, okay? And that can also cause a hunger syndrome. And then another thing that may cause a hunger syndrome is if you have a lot of brain stem problems, right? Because remember, I said that everyone regards the autonomic nervous system as a two-neuron system. And that is certainly what you should learn, for example. But remember, I said that that is not really true. I said that many of those fibers, I mean your sympathetic nervous system, in fact your autonomic nervous system, okay? Both sympathetic, parasympathetic, whatever, they both start in the hypothalamus.

So the thing is, those hypothalamic fibers that descend from the brain and come all the way to the spinal cord to hit like your thoracolomba spine on nerves, okay? For example, in the sympathetic nervous system, those hypothalamic fibers, they actually come down in the lateral brain stem, okay? They come down in the lateral brain stem. So if you have like a problem with like a pica, right? I think that's what's known as like your posterior inferior cerebellar artery. If you have a pica infarct, I think that's what they call Wallenberg syndrome. You can essentially infarct your lateral medulla, right? Or if you have like an Ica problem, you can infarct your lateral ponds, okay? Those people will have something called a central honours syndrome, right? You'll have a central honours syndrome. And it will present with the toses, meiosis, and hydroces and whatnot. But here's where your friends at BMB and you can get sneaky, sneaky, right? The thing is, if a person has honours syndrome, right? Usually they just have toses, meiosis, and hydroces. Honours syndrome, basically, from the other causes, right? So like the panchostrumor or the carotid artery dissection or the thoracic outlet syndrome with like the cervical rib. But if you have an infarct of your lateral brain stem, right? In addition to the honours syndrome, they have the lateral honours syndrome. Guess what? You also have like contralateral problems with pain and temperature sensation from the body. Let me see.

Hmm, divine. Why is that? Well, guess what? Is there any of the spinal tract that for some reason travels in the lateral brain stem, right? I really hope you're telling me about the spinal thalamic tract. Your spinal thalamic tract travels in the lateral brain stem. And remember, it's already decorated at the level of the anterior white comission before it ascends in the lateral brain stem. So guess what? If you have an infarct of paika, you have an Ipsillateral honours syndrome because the lateral brain stem is screwed. You have a contralateral spinal thalamic tract lesion. And you would also potentially have like problems with certain cranioeners, right? Like, you may have like cranial line cranial 10 problems, cranial 8 problems, okay? So those are kind of like high yield things you want to keep at the back of your mind. If you see like pain and temperature loss on the contralateral side, it's a lateral honours syndrome, where you see things more along the lines of like, oh, they cannot, the lacrimal glands don't work, or they have like a bell spalsy, right? Then you're thinking more about an aica infarct, okay? That's a lateral pontine lesion, okay? All these lesions, I'm going to revisit them again in future podcasts, but I'm sort of giving you a preview of coming attractions if you make. Now, let's see, is the annual of the thing I want to say about the sympathetic nervous system? I think that's all I want to say.

I mean, this will probably be my shortest neural podcast because neural is just a big subject in and of itself. But I mean, let's see, they knew the things I can add to this short podcast. Well, I guess we can real quick talk about like your glial cells, right? This is super easy. Glial cells, the Alexa port cells in the nervous system. We can have like the schwan cells, right? Remember, schwan cells can myelonins only one accent, and they have the cells that are attacking Guillembury syndrome, right? And remember your schwan cells actually come from neurocrest, right? Contrast all your legal dangerous sites, a singular legal danger site can multiple myelonins multiple accents, right? And your legal dangerous sites again come from neurocrest. They don't come from neurocrest. And remember that oligodendroglyomas, right? They have like that classic of fried egg appearance when you do on histology, right? So fried egg appearance, your schwanomas, remember, a person can have like multiple schwanomas, especially in the setting of neurofibromatosis type 2, right? Like bilateral acoustic neuromas, those actually schwanomas. You may see it define, come on. Schwanomas, we usually find them at the cerebellal point in angle. Okay, that's a great thought. But remember, I said your cranial nerves are derived from what? From neurocrest with what exception? Cranial 2, right? Remember, cranial 2, your optic nerve is actually derived from the diencephaline. Okay?

So, which is derived from your presence cephalon? Remember those primary secondary vesicles? I talked about it in the prior podcast. So, your cranial nerves are derived from the peripheral nervous system. So, guess what? They are innervated. But, I mean, they are malinified by things that come from, guess what? The peripheral nervous system, like what? Your schwan cells. Okay? So, that's why you can have schwanomas in the brain. Okay? Not all malinition that you find in the, like above the neck, has to be from oligodendrogensites. Okay? It can also be from schwan cells because your cranial nerves with the exception of cranial 2 are all derived from neurocrest. Okay? So, again, super, super, super, super high, you to understand these things. That's why you see me going into the struggle to explain, right? Again, you can just memorize stuff where you can understand if you understand it. When you get those questions that 95% of people get wrong, you'll be able to whizzle your way through those because you just have this detailed understanding of what's going on. And then don't forget your astrocytes, right? Your astrocytes, the, they are like, basically help with maintaining like the blood-brain barrier. So, that's kind of important to know. We have like many kinds of astrocytomas, like GBM, right? So, like glial blastoma multiforme is a kind of astrocytoma, but that's something you probably won't see on your exam.

Don't forget your appendomo cells, remember your appendomo cells, actually like line your ventricles, right? Although you want to be careful, there is actually a type of cell that is derived from your appendomo cell. It's known as a chloride plexus cell. Those chloride plexus cells are the cells that make CSF. They are derived from appendomo cells, but they actually like their own cell type. Chorite plexus cells, they make CSF. But the thing is, if you want to circulate that CSF, you need like Cilia, right? And appendomo cells have Cilia that they use to essentially circulate CSF. And then don't forget your microglia. They are not derived from Ectroderm, right? They actually derived from Miso Derm. They are like the CNS microphagias. And the thing is, for some reason, the HIV virus loves to infect microglia, right? So, a person can get like reactive gliosis in the setting of HIV infection. And then, I mean, your neurons, I mean, I guess I can also talk about the things that come from neurocreditants. So, I've sort of talked about many of them in the prior podcast and many of them in this, like the early part of this podcast. But don't forget things like your, like I said, like your post-gongronic auto-nominated nervous system neurons, your chromatin cells of the adrenal medulla, right? Your melanocytes, right? Your melanocytes, that's why many of these, like some, you see like some skin tumors being like S100 positive. Your melanocytes come from neurocrest. Your P.A.

matter, your arachnoid matter, those all, so those are together known as the leptomanages. Leptomanages, I believe, is your P.A. and arachnoid. Pachymenages, I believe, is your dura and arachnoid. But leptomanages, P.A. arachnoid, they all, they both come from neurocrest, your shwan cells, your don'toblasts, that help you make teeth. They all come from neurocrests, okay? Your C cells, your clear cells, right? Your paraphonicular cells, also that help you make, those help you make calcetonin. Yes, your paraphonicular cells, they help you make calcetonin. They all derived from neurocrest. Yeah, they all derived from neurocrest. So again, super, super high yield to know the things that come from neurocrest, right? So again, your C cells, remember calcetonin helps you calcetonin down your blood calcium, okay? They all derived from neurocrest cells. And then, what if they give you a question about a child that has like, by temperal chameleonopsia, so basically like tonal vision, right? And then they tell you that, oh, they do imaging of the head, like a CT scan of the head, and they find like a supercellum mass that is calcified. And then let's see, they tell you that, oh, when they do a biopsy or whatever, they see like, mudo oil looking fluid emanating from the mass, right? That's actually not mudo oil. It's more like cholesterol, but hopefully you're thinking about a craniofiring geoma. They love to test it in the context of, it's an embryological, like derivation, right?

From like, raki spouch, okay? Remember, that's like oral, that's like a fancy name for like oral ectoder, okay? So something you want to keep at the back of your mind. And don't forget that your pituitary gland, right? Obviously, no, your pituitary has two parts. Antirampusia pituitary, your pituitary actually comes from neuroectoderm, right? So like neuro tube, but your anterior pituitary actually comes from raki spouch, okay? So again, just one of those weird, high yield things you want to keep at the back of your mind for, for exams. Let's see, guess maybe I could stop here. You know what? Just real quick, I promise, two more minutes. I mean, a neuron, I'm just trying to think of the things that first aid covers, like a neuron, right? Has like a cell body, has, I think it's known as like the soma. And then remember, neuron is a kind of cell, right? So you should be able to make protein, right? So we actually have like rough endoplasmic reticula in a neuron. It's known as like nestle substance. That's where you basically make like neurotransmitters, remember neurotransmitters are kind of protein. And then you can move those neurotransmitters to the synapse, right? You can move them from the soma or the cell body of the neuron to the synapse by using like antigree transport. Don't forget that that's done by kaini sin. That's something that actually shows up a ton on the USM Ls. That's something I definitely want to know.

I believe I've actually mentioned this in one of my self-hesiology podcasts from back in the day. So, so antigree transport that's done by kaini sin retrograde. If you want to go from like, oh, if you want to go from the synapse all the way back to the cell body, you do that with diney. You do that with diney. So you may say divine, why is this necessary? I already said that, oh, antigree transport helps you move neurotransmitter. Fine. The thing is that retrograde transport, it's good, but it's also bad, right? So, I mean, how do you think like viruses like polio, like rabies, or like even like the tetanus, like toxin, or like VZV? That sort of hangs out in the trigeminal ganglia. How do you think those things go from, how do you think those things like you get the infection and then it goes and hangs out in cell bodies? How do you think that happens? Happens through retrograde transport, okay? So that's why it's high to know that. So, just something to keep at the back of your mind. And remember, right, you're kaini sin diney, right? These are all like microtubular structures. So, I think that's where I'm going to stop. As I always end with, I do offer one-on-one tutoring for the USM, USMED step one, two CK, two CSN step three. I also do like application advising. So, if you're a med student going into med school, so like AMCA's applications or interview prep and all that crap, or if you're a med, if you're a med, no.

If you're a college student going to med school, or if you're a med student going to residency, right? So, like era's applications, I do like consulting and whatnot for that. I mean, I've been on the admissions committee of a top three med school, so I have a lot of experience with that stuff, like interview prep, writing personal statements and all that fun stuff. And then, if you have like shelf exams or preclinical exams, that you need to study for, I also offer private tutoring for those. And then weirdly, if you need to do it for regaining chemistry, especially synthesis, I am an expert at stuff like that. So, I can help you with that. And again, I have a lot of free resources on my, everything on my website is free, right? So, don't forget your shelf exams, step one, step three, internal medicine exams. There is many, many, many free podcasts and videos on my website. So, please share, spread the word, and I will see you in the next podcast. Have a wonderful day and God bless you.

Neural Crest.

Adrenal Medulla chromaffin cells.

Sympathetic has short pre-ganglionic fibers and long post-ganglionic fibers; Parasympathetic has long pre-ganglionic fibers and short post-ganglionic fibers.

Pupil (miosis), eyelid (ptosis via superior tarsal muscle), and sweat glands (anhidrosis).

Acetylcholine (A Ch) acting on Muscarinic receptors.

CN III, VII, IX, and X.

Neural Crest.

Oligodendrocytes.

Post-ganglionic autonomic neurons, chromaffin cells of the adrenal medulla, melanocytes (and Schwann cells).

Acetylcholine (A Ch) acting on Muscarinic receptors.

CN VII (Lacrimals/Salivary), CN IX (Glossopharyngeal/Parotid), and CN X (Vagus).

Schwann cells myelinate only one axon; Oligodendrocytes can myelinate multiple axons.

Rathke's pouch.

Neural Crest.

Oligodendrocytes.

Post-ganglionic autonomic neurons, chromaffin cells of the adrenal medulla, melanocytes (and Schwann cells).

Acetylcholine (A Ch) acting on Muscarinic receptors.

CN VII (Lacrimals/Salivary), CN IX (Glossopharyngeal/Parotid), and CN X (Vagus).

Schwann cells myelinate only one axon; Oligodendrocytes can myelinate multiple axons.

Rathke's pouch.