Autonomic Nervous System PDF

All right, so we are going to redo the autonomic nervous system recording here So the first part we're just going to go over some basic information about the autonomic nervous system, and then we're going to spend Time on the sympathetic nervous system Okay, so learning objectives of course autonomi...

All right, so we are going to redo the autonomic nervous system recording here So the first part we're just going to go over some basic information about the autonomic nervous system, and then we're going to spend Time on the sympathetic nervous system Okay, so learning objectives of course autonomic nervous system. What is it? What does it do right? So this is going to control Involuntary unconscious stuff going on inside your body right so not only are we going to control that via motor But we also have some sensory innovation going on monitoring what's going on in our bloodstream and also in terms of Visceral sensory or if our organs get Inflamed or there's something extremely painful going on so it's going to primarily work through motor Innovations so when we talk about the autonomic nervous system We are primarily talking about that efferent innervation unless we specifically talk about the efferent arriving innervation, right? So this is going to impact smooth muscle, which is going to be the muscle that we find in our organs modified cardiac muscle So our muscle of our heart is a little bit different than the other muscle we have and then glandular cells Which will secrete and then extrude the materials that they make whether that's directly into the blood supply or? On into onto a certain surface or area our sensory is going to travel alongside those motor pathways But of course they are going to the information is going to travel in the opposite direction, right? So while motor comes out sensor is going to travel the other way and when we talk about interim posterior Horns and anterior and posterior roots sensory still will go through posterior structures motor will go through the anterior structures Okay, how does it communicate? This is quite simple and Straightforward but something that's very important to keep in mind, right? So we are going to have a series of two neurons, right? So we have a first set which is going to call be called pre ganglionic and then the second is post ganglionic, right? So in this image here, we can see the neuron cell body Remember that there's going to be many of these in its axon Axon then we'll synapse on the second kind of set of neurons, which are our post ganglionic, right? So we are talking about this communication here in terms of ganglionic, which will then send that information to the effector organ So in this image we can see we're going to have our pre ganglionic neurons right here for an example Coming through and maybe going to our post ganglionic neuron right here and continuing on, right? So it's always going to consist of two we're starting as those nerves Or the series is coming out of the spinal cord the central nervous system We will see multipolar and Unipolar neurons just like we saw in terms of our somatic sensory and motor organization Pathways involved, right? Pathways involved, right? So we talked about pre and post ganglionic pathways now for motor innervation more specifically, right? Our pre ganglionic neurons really are what we kind of have come to think about as lower motor neurons, right? So before when we talked about somatic sensory and motor only our somatic motor We talked about lower motor neurons as peripheral nerves We will still include peripheral nerves in this But we would now add what we call splenchnic nerves as well here So lower motor neurons is kind of what you can equate to these two They're going to start in the central nervous system gray matter for our purposes, right? Exit the central nervous system via that anterior root because it's motor Sit-ups on autonomic ganglia which are going to be located in different places Depending on which pathway we're looking at then our post ganglionic neurons are going to be those that form These things that we call splenchnic nerves And then they're going to travel send innervation to organs in the body or the skin Alright, so in terms of our different divisions of the autonomic nervous system. We do have sympathetic and parasympathetic Again, we're talking about these efferent fibers unless we talk about sensory specifically So sympathetic is going to be that fight or flight situation or pee, right? So we have another response that we can call on which is to urinate on ourselves to make Enemies people who are threatening us not want to come near us, right? so this is our flight our fight response and Primarily this is going to regulate vessels. So our arteries and our veins through vaso motion what we mean by this is that as a Dilation or constriction of the arteries and of the arteries in our body, right? So if we have it dilated we can send more blood To places which means more oxygen supply or we can decrease What we're sending in order to you know, send other places. So if we decrease the size of our Of our vessels, we're sending less of our resources there Parasympathetic is basically just bringing our systems back into homeostasis Which allows us to rest and digest so we can call this catabolic for sympathetic anabolic state for parasympathetic All right, so we walk through this We're going to go through these Again, kind of throughout the lectures here But we want to think about what happens to the sympathetic and parasympathetic nervous nervous systems in these locations So for the eyes if we have a sympathetic response We are going to allow for people with dilation specifically when we're talking about the eyes And that allows more light to come in to perceive our surroundings more fully Our parasympathetic kind of response is going to bring our pupils back to that normal constriction Items that we will look at in this block that are related to this is going to be Are the ciliary muscles the ciliary muscle within our eye that controls pupil dilation in terms of our skin? We can we are going to do a few things that's going to We're going to increase Or allow ourselves we're going to send Innovation to our erector pili muscles, so we cause goosebumps. We are going to increase Pseudomotion was just sweating so sweat glands And we are also going to I can't think about the third one right now But it'll come to me cuz it's on a side here there's no parasympathetic response that goes to the skin because that's just Stopping or letting these kind of run their course back to parasympathetic state Lacrimal and salivary glands right the lacrimal gland is going to allow us to create tears Salivary gland obviously allows us to create saliva during our sympathetic nervous response. We don't need to Spend our resources on these things so it's sympathetic is going to decrease Activity of the structures parasympathetic rest and digest we want to be able to create slides So we can eat is going to increase that The heart sympathetic response we're going to increase heart rate And we are also going to increase the amount of the volume of blood that we're passing through here, right? Parasympathetic we're not going to bring everything back down Blood vessels this is going to depend on the location So this is kind of a really kind of crucial concept here blood vessels for example Two structures that will help us get away and run away such as blood vessels supplying ours skeletal muscle Will increase in diem diameter. So it's going to be vasodilation, right? If we are in a sympathetic response, we will vasoconstrict makes smaller our blood vessels The ones that are going to for example our digestive system because we do not need to worry about Digesting food while we are trying to survive so it depends on the region No sympathetic response is just we just go back to our normal vascular diameter Lungs we want to be able to bring in more oxygen to supply for example our skeletal muscles And so our lungs in the same way are going to are the tubes that create our lungs can get bigger and smaller, right? So bronchodilation our tubes are going to get bigger allowing more oxygen to pass into our body more carbon carbon dioxide to go out versus vasoconstriction Which isn't going to help us get away, right? So vasoconstriction is going to belong over here in our Paris Bronchoconstriction, excuse me in our parasympathetic kind of normal state, right? Digestive system we've already talked about that our digestive system. We are going to decrease The amount of blood through vasoconstriction going there parasympathetic We're going to allow that to go back to its normal state and have pretty sizable, you know Good blood flow through the digestive system The same is going to be related to the liver and the gallbladder when we think of those as a collective digestive unit or accessory organs But we can also increase the amount of for example a glucose that is Going to come from these locations as well Okay Urinary system we do not need or want to pay We don't want to pee while we run, right? We don't want to be urinating on ourselves while you run or fight unless it's that specific response that we can sometimes see in Juveniles and so forth, right? So urinary activity is going to decrease Parasympathetic is going to allow that to increase the general system. This is going to kind of fall outside the norm In terms of fight or flight, right? So we use the the the terms point and shoot to help us Remember this point is going to be for parasympathetic and meaning we're sending blood There's a dilation to our erectile tissue, right? So erectile tissue is going to respond or be innervated by our parasympathetic nervous system Sympathetic nervous system shoot for s is going to allow ***********, right so it's a combination of these Systems of the autonomic nervous system that allows for reproductive reproduction And then our super renal gland this one special it's gonna have its own slide Our super renal gland is a gland. Here's our a kidney. Hey, that's pretty good for me. I'm sitting above or superior to the Kidney is our super renal gland. This is going to secrete adrenaline so Adrenaline is going to allow us to have a lot of energy quickly, right? And it's going to directly into the blood supply secrete adrenaline. So increase in terms of Really cool because the cortex of this of this organ is actually Nervous system. So pretty cool. It's another place neural crest cells will show up Okay, so our to to kind of further talk about our two distinctions between sympathetic and parasympathetic The sympathetic nervous system is also known as our thoracolumbar System and this is really helpful and important to remind us of one of its unique characteristics the nerves from the central nervous system carrying efferent motor and sensory Will only leave a certain level of the spinal cord including the thoracic and lumbar level So between t1 and l2 sometimes they go to the hoi down l3 in different resources These are the only locations that sympathetic fibers Can leave the central nervous system to go where they need to go, right? And so we're going to do a little drawing here to help with this System this organization because it's Throughout my years of teaching this is very complex for students because it's just weird Okay, so We will have really three different places. We're going to provide innovation We'll talk about how we send in a region in different ways So in terms of our dermatome We will have sympathetic response in our skin that we already talked about, right? So Goosebumps or sweating and so forth. So these will travel Specifically with our spinal nerves. So when we talk about This division of the sympathetic nervous system We're going to recall those nerves that we learned in the last block So think about our cervical plexus up here think about our brachial plexus our thoracic Organized fashion and then our lumbosacral plexus This these axons will join up with those spinal nerves to travel to where they need to go in the associated dermatomes Okay cranial glands and thoracic organs are going to be innervated in another pathway another kind of a distinctive pathway And we are going to have to travel in this structure that we call the sympathetic trunk The sympathetic trunk is going to go the entire distance of our of our torso up into our neck, right? torso and down the pelvic cavity So the the main thing is we are going to send fibers from our thoracic levels Our central nervous system is going to get on the sympathetic trunk here those fibers They may have to travel up to reach our head and neck and upper limb structures, right? Because there's no way for those fibers to get on up here in the cervical region Or they may get on and travel down in our sympathetic trunk to reach Aren't the nerves that are associated with or that provide innovation to? Our pelvic organs here, right? So for these places, I should have probably added in pelvic, but actually we're going to talk about that in terms of abdominal So ignore that pelvic region thing So abdominal organs, which is what we want to talk about. So abdominal pelvic organs together They are going to do another go through another Organized pathway and we are going to start in that sympathetic trunk get on his start in our central nervous system get on the sympathetic trunk pass on through in synapse in Ganglia that are located in our abdomen So they had a unique and individual pathway. So abdominal organs here are the weird things out That will do something different Okay, so the parasympathetic nervous system is going to be also called the cranial sacral division, right? because we have three excuse me for cranial nerves and Really three vertebral levels are free Three spinal cord levels. I'll contribute to this and that's it right? So cranial Sacral tells us this is where our fibers are going to originate The way we innovate all of the organ stuff, right is going to be through the vagus nerve So we are going to see the vagus nerve a lot in the coming months Right this cranial nerves are going to be going to specifically be three Seven nine and ten and we are going to revisit these when we do our cranial nerve Stuff our lectures, right? Sacral spinal nerves specifically s2 through s4 will be part of the parasympathetic nervous system Okay, these are images to help contextualize these gross anatomical structures, right? So when we talk about for example our sympathetic trunk and our paravertebral ganglia We're gonna think way way deep in our thoracic cavity here and in our abdominal cavity so we are looking at this image right here the heart and lungs have been taken out as well as the The tissue covering and our posterior thoracic wall then we can see this structure called the sympathetic trunk, which is also called the string of pearls that is the entire structure then Individual structures the individual ganglia that help create that sympathetic trunk are going to be the paravertebral ganglia All right, because there's a pair one on either side ganglia Okay, we also have something called pre vertebral ganglia These are going to be the ones that are associated with the abdominal cavity Pre vertebral in front of the vertebra really in front of the aorta is where we are going to find these ganglia So here around our ciliac trunk. We have more around our Superior mesenteric artery our renal arteries off to the kidney and then our inferior mesenteric artery right here So these are going to be named for these big important blood vessels that come off our descending abdominal aorta Alright, we can see these structures again in this location right so in terms of our location of our Parasympathetic ganglia from the cranial division we're gonna find these in the head There are four that you need to know that are associated specifically with parasympathetic Intervation we have our ciliary ganglia. This is gonna be located in our orbital cavity right behind the eye here. So Think about back the orbit. We have that sphenoid and so forth The pterygopalatine ganglia is right here it is actually sandwiched between our palatine bone that L- shaped bone that makes up the back of our nasal cavity and The the pterygoid processes of the sphenoid. The the pterygoid processes of the sphenoid. This is actually the pterygopalatine fossa We have our submandibular ganglion, which is pretty straightforward for where it's at and then our otic I always kind of think of the ear for this one. Those are all going to hold that that second Layer not layer second set of neurons in our nervous system autonomic nervous system Okay, so we are now going to talk about The differences between these two in terms of length. This is going to play into Helping us understand our autonomic nervous system plexus, right? So we will in our next lecture cover where these fibers sympathetic and parasympathetic Run next to one another creating this network of nerves and we can see that in here So this network of nerves that are surrounding these ganglia actually hold or contain both sympathetic and parasympathetic So when we think about our sympathetic nervous system, this is going to be our who a very wonky Spinal cord, but that's where it is We're going to have our pre ganglionic fibers start out here and they're going to travel a very short distance before they synapse on their On the post ganglionic fibers, right? So these are going to be either in that pair that that sympathetic trunk or the prevertebral Ganglia either way the pre ganglionic fibers are short so we can think about these short fibers That will synapse on our post ganglionic neurons Which are going to be much longer because they have to travel to these individual organs, right from either those pre vertebral or pair of vertebral ganglia in comparison our parasympathetic trunk as our our parasympathetic Intervation is going to let's draw this the brainstem here. For example, we're going to have our instead of We're going to have in here our nice spinal cord Brain stem Nuclei in here where we'll have our first neuron for seven neurons begin These are going to come out and travel a long way Before they synapse in or on one of those four cranial ganglia So maybe this is submandibular or otic and then it's going to have a short distance to travel that information before it finds its target organ or reaches that target organ So if we compare it, we're going to have a very long Preganglionic fiber, which is actually just our cranial nerves for these certain ones, which will synapse On a ganglia that's going to be either one of those four cranial nerves or in the sacral portion Ganglia that are within or very close to the organs that they innervate with a short fiber Why do we care? So when we look at this when we look at these plexuses that we see in this image We will be able to note that these plexuses based on their location are going to be made up of our our post ganglionic sympathetic neurons and our Preganglionic parasympathetic Axons, I should say axons instead of neurons, right? right? So we're looking at different steps in these Systems when we look at those plexuses Okay, so now we're going to move on to the sympathetic nervous system more specifically All right, lots of learning objectives But I want to I want you to be able to draw these out and notice specifically what I'm asking of you All right, so just just take one step back for a moment We want to bring this into what we've been learning about the nervous system in general So where do our upper motor neurons actually start? So we know this from when we did our somatic motor and it's going to be the same place, right? So think of our pre central gyrus that will be found in the frontal Cortex or frontal lobes, right? so our pre central gyrus is associated with motor because it's anterior and Just to help you kind of link back to all that stuff And then we will have our hypothalamus Master autonomic control center Playing a role in the diencephalon. So we can get that all back together So while we're talking about these first and second steps, we're ignoring kind of this first essential component So we start here at the spinal cord level for our pre ganglionic neurons just to help you kind of contextualize this All right. So pre ganglionic neurons if you said this a few times now, they're also called Pre-synaptic in case you see that term. So those cell bodies Like we have said start in the spinal cord Specifically in the gray matter because that is what gray matter is between the levels of t1 and l2 or 3 right because this is where we have these first Steps located these first neurons located specifically. Steps located these first neurons located specifically. We actually have an extra little Extension of our gray matter called the lateral horn or the inter-medial lateral column So these are only located in the spinal cord level here So if we go up to c8 or c7 6 5 4 3 2 1 We will not see lateral horns because we don't have our neurons there for sympathetic nervous system to start Okay Then motor neurons are going to do what we expect them to do right do those anterior structures So here is our in our lateral column here our lateral horn We are going to have that motor neuron coming on out through that anterior root Join up with our spinal nerve, which is really technically only there's a small part here get on and go through our anterior root here After our anterior, sorry her anterior ramus in this location We're gonna get on the structure at the sympathetic trunk, right? We're gonna get on the structure at the sympathetic trunk, right? We're only showing one level but really there's ganglia all the way down For this so this is gonna happen at each level t1 throughout 2 or 3 Then we're gonna get on the sympathetic trunk via the structure called the white ramus. So this is the white ramus right here I mixed this up during lecture because the way we get off the sympathetic trunk Is going to be through what we call the gray ramus. So white ramus to gray ramus. So Watergate was what Sabrina Suggested to help us remember which I will probably use for a very long time. So Watergate White ramus we may once we get on the sympathetic trunk This is where the pathways will differ everything will get on the sympathetic trunk But it might do something different depending on what the target is the target organ is We might travel up the sympathetic trunk. We might travel down the sympathetic trunk And we might actually just get on the sympathetic trunk at that level synapse and then leave When those fibers leave and I'm going to change color here When those fibers get off the sympathetic trunk on this gray ramus or via this gray ramus If it goes and joins up with the anterior ramus here, it's going to do a crazy loop the loop It can also get off and go through our posterior ramus specifically Only really to innervate the skin on our back the along that midline there, right because that's our epaxial muscles Versus a haphaxia muscles where we hug. So just one more time. We're gonna have those fibers get on Our sympathetic trunk via this white to ramus They may travel either way unless it's going to the abdominal organs are going to synapse in Right before the exit. So if we're getting on leaving immediately, we're gonna get on synapse leave via this gray ramus and Most of the time do a nice loop loop here All right, that's assuming it's going to skin if we are doing our Organs we are going to get off this sympathetic trunk and go via these splenchnic nerves, but we'll see here in a minute All right post ganglionic neurons. All right post ganglionic neurons. I kind of already talked about them Cell bodies for the post ganglionic neurons, right? Cell bodies for the post ganglionic neurons, right? So where those pre ganglionic neurons synapse are going to be located in either These individual structures that help create or make up the sympathetic trunk which are going to be the pair of vertebral pair of right on either side or These nerves will get on the sympathetic trunk travel Leave a sympathetic trunk and in synapse on post ganglionic neurons in our pre vertebral ganglia here, right? So so bodies are in these ganglia because that's what ganglia are their neuronal cell bodies Gray matter outside the central nervous system where we're going to meet those secondary that post ganglionic neurons When we look at our pair of vertebral ganglia a little bit more specifically How they're organized for the most part. How they're organized for the most part. There's about one ganglia per level Specifically and especially when we're in the thoracic region, but really between that t1 to l2 or 3 Right, so that's going to be about this level here When we get into the cervical level, so again, we can get on the sympathetic trunk at spinal cord specific levels But our sympathetic trunk is going to run the entire length of our vertebral column When we get up to our cervical levels, we only have usually about three cervical ganglia Sometimes there's more so we have a really big one our superior cervical ganglia our middle cervical ganglia and our inferior cervical ganglia So they're organized a little bit differently Another landmark or important structure is the ganglion in par is going to be at the most Inferior level here rate in anterior to with the sacrum and the coccyx is going to be called the ganglion in par All right post ganglionic neurons again Our pre vertebral ganglia are going to be located like I said earlier anterior to pre in front of the vertebral column and the aorta and be named for these large vessels that come off the Or which are going to be called the ciliac trunk the superior and inferior mesenteric arteries and the renal arteries So we will have in association with those locations Ciliac ganglia. These are pre vertebral ganglia, right superior mesenteric aortical renal ganglia and inferior mesenteric ganglia They are named for the vessels and are Prevertible ganglia these will provide Innovation to or be part of the pathway that supplies or abdominal pelvic organs specifically Sympathetic divisions there are even more divisions beyond The autonomic division the sympathetic and parasympathetic division and now we are going to look at These two divisions of the sympathetic nervous system the parietal division and the visceral division parietal is going to send sympathetic innervation to the skin Visceral is going to send sympathetic innervation to the organs, right? If we're talking about sensory, this is going to receive visceral sensory information from the organs Which usually is going to have to be some sort of extreme Trauma or Necrosis if necrosis is occurring we can feel that as sensory as well So going back to the skin here, we're going to have our sweat glands our smooth muscles and our vessels Our vessels have several layers one of those layers is smooth muscle and then our erector pelae muscle All right, so we got to go way back to the integument stuff When we look at that parietal division a little bit more specifically we're going to use these terms, right? So know these terms and what they mean vasomotion is going to be vasoconstriction of dilation, right? So whether we need to Take blood away from the skin Perhaps since to send more blood to our brain our heart and our skeletal muscle Pseudomotion is sweat right and the pelo motion is going to be those erector pelae muscle contractions for goosebumps These are all Things that can happen during a sympathetic response in our skin like I said before These fibers are going to be associated with our spinal nerves that we already know and the dermatomes that we know is that we Kind of introduced right? So if I were to draw on here but a change not from blue to a different color here we have our our Pre ganglionic neurons getting on the sympathetic trunk right here And then they'll do that loop-to-loop fun thing and then we will synapse right before we leave On that that sympathetic trunks aren't going back a step Synapse on the sympathetic trunk and then go with our spinal nerves to whatever level layer Level of a dermatome that they help provide right so you want to think about the Sympathetic response in our arm is going to go through the brachial plexus The sympathetic response in our trunk is going to go through these individual spinal nerves that don't make plexuses Now this is where we may go up and down travel up and down on the sympathetic trunk here, right? So if we need to provide A sympathetic innervation to the skin on the legs. We are going to get on the sympathetic trunk Then travel on it Before we do our loop-to-loop to get off right and we're going to synapse in here before we get off because we don't have a way to contribute to our most of our lumbosacral plexus Here and now it's we're gonna I think draw this out Okay, so another way to kind of think about this organization is we're at a town right here This is going to be pre-ganglionic Phil Pre ganglionic Phil, but we want to go up here into head and neckville Head neckville right these two little towns, but there's a river in between here Right, so there's this river How do we get across the river or how do we get a car across the river? Don't say fairy because I realize that that is another option, but we're gonna say bridges, right? So we're gonna have bridges only in certain locations We don't have enough money to build a lot of bridges and then we're gonna have a highway over here that we want to meet This highway and we'll make this clear already. We've got our median along the highway, which is gonna be our Sympathetic trunk highway and our river which is just Imaginary for this purpose, right? Imaginary for this purpose, right? So we want to get here to here But we only have bridges From here down south into south, right? So this is bridge T1 we have bridges t1 the whole way down to l2. T1 we have bridges t1 the whole way down to l2. I want to get on the sympathetic trunk from this town Cross this bridge then travel up this sympathetic trunk highway to get to This other town, right? This other town, right? So because we don't have bridges which are going to be our white Ramai In or above t1 we will have to travel to get to the higher levels So let's do this again for four legs. So if we have a town here This is where our pre ganglionic fibers are going to start. I have to cross this white Ramis bridge And get on this sympathetic highway and travel south or inferiorly Before I can get off on the right spinal nerve to go to legville So hopefully this analogy works. This is why we have to travel sometimes on our sympathetic trunk because We don't provide bridges in our cervical and lower lumbar and sacral regions from our spinal cord Okay, hopefully that helps Okay, so our general pathway we've talked about here a little bit already We're gonna do our lateral column here motor fibers are gonna come here on pre ganglionic fibers. We're gonna get on our Sympathetic trunk remember this is just one level. So we have a lot of levels that this can happen I'm gonna get on through our white Ramis here All right So our white Ramis if we are not traveling up or down to other locations Then it's going to synapse on those post ganglionic fibers and then leave Most of the time or some of the time we'll get go with our posterior a miss but most of the time for this gun anterior But if we have to travel we'll get on the sympathetic trunk We're gonna travel then we'll synapse at the level that we need to leave and get off via that gray ring One way one helpful way to think about this might be that our white Ramai will always carry pre Ganglionic Interaction and our gray Ramai will always carry post This may or may not help. All right, so Re-establishing reaffirming why we sometimes have to go up or down When we're talking about a parietal distribution, right? We only can get on to the sympathetic trunk here But the sympathetic trunk is going to provide innervation to all of our body by joining with spinal nerves at all these levels So from t1 to l2 we're gonna get on if we're at the right level to go to that dermatome We're gonna just synapse and get off or if we need to get on the sympathetic trunk and go to the legs We're gonna use the lowest Ramai we're gonna get on Travel down then synapse before we leave Okay, so that's what this is explaining here When we talk about Let's see, what do I have here this just Explains if we are sending innervation to these three different locations or these different locations here, right? You will see gray right Ramai communicons. This is an additional term that is sometimes used to Define these structures. So gray Ramai or gray Ramai communicons as well So three possible ways to get this innervation to the skin enter Synapse and leave enter sympathetic trunk ascend enter sympathetic trunk descend And then leave with the appropriate spinal level. I Think this says the same thing but uses a different picture it does. Yeah, so just a little bit more specifics here All right Visceral division. All right, here we go So visceral division means we are sending our sympathetic innervation to the organs inside our body, right? We do have viscera of the head Specifically, we really want to think about The pupil of the eye but also we're going to bring in sensory information from Our carotid plexus from the blood that's going through the big artery Sending blood to our head because we really want to monitor the blood that's going to our head and fix it if something's wrong Right. Right. So sympathetic fibers sensory are going to come from the head as well Our thoracic viscera meaning our heart and our lungs And then our abdominal pelvic viscera Everything below the diaphragm, right? The order from superior to inferior In terms of where they are in our body will be helpful. For example our liver is the most superior of these organs and the most superior Splenitic nerves that form will go to that organ Versus our inferior structures are external and internal genitalia Our urinary bladder will be from the most inferior portion of this network All right So here we go What we can do if we look at The organs So let's see so in terms of how we travel The innervation to the thoracic organs is going to really follow the pathway That we see for our skin our parietal division But instead of getting off the white getting off via the gray rheumus to travel with spinal nerves It is going to get on the sympathetic trunk then leave via splenchnic nerves These are for our abdomen, but that's what we're going to see in the thoracic cavity. Those are going to be called cardiopulmonary splenchnic nerves We will sometimes have to get on the sympathetic trunk and travel before we synapse and Leave via those splenchnic nerves, right? So we might have to get on and travel up or we get on at the appropriate level and travel directly out of there Then for our abdominal pelvic structures We are going to do this thing where we get on the sympathetic trunk may or may not travel to a different level At level or below But we're going to travel on right on through Until these fibers get to our pre vertebral ganglia, right? So we're going to pass through These ganglia of the sympathetic trunk to our pre vertebral ganglia Then they will synapse on the post The post ganglionic neurons to go to the organs, right? The post ganglionic neurons to go to the organs, right? So only for a abdominal pelvic viscera Fibers are going to pass through the sympathetic trunk without synapsing For the skin in the thoracic organs, they will synapse in the sympathetic trunk So head and neck viscera we're going to look at a little bit more specifically because we're going to have our gray ramus Well, our splenchnic nerve is going to have a really specific name. It's going to be called the cephalic arterial branch, right? So to send information to our head and neck structures We're going to get on the sympathetic trunk from the highest level here T1 of our spinal cord, right? There's our on ramp our white ramus. We don't have remi up here So we have to travel up We're going to travel on up here and then we are going to synapse on our post ganglion neurons before we leave this sympathetic trunk or Sorry, this splenchnic nerve also Which is going to carry our post ganglionic fibers is specifically going to be called the cephalic arterial branch All right, it's going to do important things. That's why it has a special name Okay Then when we get into our our thoracic organs Some fibers are going to get on and travel up to our superior cervical ganglia And then synapse before they leave Those are specifically going to go to the heart So get on sympathetic trunk travel to one of our cervical ganglia superiorly synapse and leave to the heart or they're going to get on Sympathetic trunk Synapse immediately and then send innervation to both the heart and the lung All right, so there's two different ways that we can do this Sometimes we have to travel up So our our the contributing spinal cord level is going to be t one to t five And then our contributing sympathetic trunk level is going to be our our cervical ganglia All three of them and then t one to t five Para vertebral ganglia This is going to be important because well, we can't survive without our heart and our lungs And we need to know what provides them innervation where it's coming from, right? So our superior cervical ganglia the whole way down to t five They are all going to um send out cylindrical nerves To our heart All of these levels which is good because if we get injured at one level, we still want to make sure our heart is innervated Our lungs are specifically going to be innervated by levels t one through t five of both our spinal cord and Those ganglia that are associated at that level Right. So all of these are going to send innervation to the heart only t one through t five to the heart and the lungs Okay Here we can see these structures These structures are going I I really Think it's important to think about these in reference just to muscles and other things that we already know Here's our first rib Right here. This is our anterior scalene muscle Here's our middle scalene muscle and we'd be able to see our posterior Um, if we look behind this, right so our By our anterior scalene muscle, it's a really nice landmark for our middle cervical ganglia right here Going superior to that. Um, really we're at the top of our Middle scalene muscle. We will be able to find our superior cervical ganglia When the other direction or inferior cervical ganglia is going to be In location of these really important big vessels that send blood to our head and our neck Um head neck and upper limb, excuse me, right? This is going to be called the subclavian Which is going to turn into axillary artery and then brachial artery and these are going to send blood to the head and neck And then we can see there the rest of these pair of vertebral ganglia individually, right? This is a pair of vertebral ganglia That help create or form this entire structure of the sympathetic trunk All right, so abdominal pelvic viscera We know that these are going to take a different path Right, they do not synapse in this sympathetic trunk like all the rest of it They are going to synapse in our pre vertebral ganglia, but we still pass through sympathetic trunk And we still are going to leave it like thoracic organs via these splenchnic nerves So as you can see these fibers are going to get on pre ganglionic fibers are going to get on the sympathetic trunk They're going to leave via these splenchnic nerves And then travel to pre ganglionic or travel to our para prevertible ganglia synapse on our Well post ganglionic neurons and then that'll go to innervate different structures, right? So they're going to pass through to find their post ganglionic fibers Okay We do have a small number of fibers that will get on the sympathetic trunk and travel inferiorly Before they leave to their ganglia. These are going to be specifically the sacral splenchnic nerves Sacral splenchnic are part of the sympathetic We will also have pelvic splenchnic nerves that are part of the parasympathetic race of sacral for sympathetic Parasympathetic for pelvic. Parasympathetic for pelvic. Those are important things to distinguish here All right. We're going to look more specifically at these now So our four splenchnic nerves that we will know are the greater lesser least lumbar splenchnic nerves The whole thing is greater thoracic lesser thoracic so forth, right? And we are going to have specific spinal cord levels that contribute to these These are important to know in case of a spinal cord injury, right? So our greater thoracic splenchnic nerve is going to be From levels t5 to t9, right? From levels t5 to t9, right? So note again We did talk about t5 already helping provide innervation to the thoracic organs It is also going to provide innervation to our greater thoracic splenchnic nerve All right, so t5 to t9 are going to send fibers to create our greater splenchnic nerve, right? Then lesser thoracic splenchnic nerve is going to be t10 and 11 Least is t12 and lumbar are just the lumbar ones, right? So one way to think about this is greater is going to have most the most contributions Lesser is only two Least is only one contribution and lumbar is just the lumbar ones, right? Again, we're only going to go down to the level of t1 because that is where our on-ramps From the spinal cord are going to exist So splenchnic nerves will then go on to synapse within those Prevertible ganglia that we just saw that are named for those large vessels that they're next to We have our greater splenchnic nerve synapsing in the ciliac ganglia Lesser is going to synapse in the aortico renal ganglia And I know there's some variation in terms of what we see here Least splenchnic nerve is going to synapse in superior mesenteric ganglia and lumbar inferior mesenteric ganglia Right then our post-ganglionic fibers are going to travel from there to these different organs Organized from superior to inferior superior to inferior contributions Okay So taking one more step back what we can do now is say spinal nerves T5 through T9 are going to send sympathetic innervation to our superior most Organs which are the stomach the liver the gallbladder pancreas and spleen, right? These are all very superiorly located in our abdomen Right and they're going to do that through this pathway T5 through T9 spinal nerves to that greater splenchnic nerve Then into uh, and synapse on our post-ganglionic fibers in the ciliac ganglion to provide innervation to these organs Same thing with spinal nerves T10 and 11 They are going to provide innervation to the kidney in the super renal glands Right through that lesser splenchnic nerve which meets up with that aortico renal ganglion on either side Um and send innervation to the kidneys. Um and send innervation to the kidneys. So our really our ultimate goal is to know which spinal nerve levels Are associated with which splenchnic nerves? And of course the ganglion, but what they're providing innervation to right? So if we mess up this part of the spinal cord, this is what's going to be impacted in terms of our sympathetic nervous system and then Again, same thing for spinal nerve l1 through l 2 3 lumbar splenchnic nerves inferior mesenteric ganglion for post- ganglionic fibers This is going to provide an innervation to our distal large intestines ****** urinary bladder all these structures that are inferior When we talk about proximal versus distal for the tubes in our bodies or whether that's our gut tube or our our arteries and veins We're going to think about the distance that that stuff inside of it has traveled, right? So this is going to be proximal to the heart if we think about it as an artery versus distal even if this This tube is all bundled up, right? This tube is all bundled up, right? So it's how far the stuff has traveled All right. This is just I want to bring in What these are when we look at our ganglia our pre vertebral ganglia again, this is going to be Defined by which large vessel that they're going to be around here is our ciliac trunk. here is our ciliac trunk. It's going to provide our vascular supply to those same organs that are Celiac ganglia will send Post-ganglionic fibers too, right? Post-ganglionic fibers too, right? Here's our superior mesenteric ganglia or superior mesenteric artery Our renal arteries going to our kidneys on either side They're going to send off blood vessels to our super renal gland as well And then our inferior mesenteric ganglia is arteries way down here. And so that ganglia that's next to it will be The inferior mesenteric ganglion. There's a lot of variation in terms of the number and Really location of these ganglia, but we're going to name them for what they're closest to in terms of those large vessels Um, and then we have our exception this cool Cool coolest organ in the body. I don't know. I like the spleen still But the super renal gland, right? So this is going to be One of the big things that doesn't transverse sympathetic nervous system is to Produce adrenaline to help us get out fast or fight. Well, right? So our our our super renal gland The cortex the outermost layer is actually Where our neurons in this or post ganglionic cell bodies are going to be so this Pathway, we're going to start in that lateral horn We're going to come out that anterior root We're going to go through that spinal nerve We're going to go through the white rheumus to get on the sympathetic trunk Then we're going to leave we still haven't synapse yet, right? Then we're going to go through pre-vertebral ganglion still haven't synapse Take nerves go through plexuses to meet the the post ganglionic neurons in The cortex here which are then going to send its fibers to the medulla of this organ and tell it to do its thing Right. So this is a pretty cool unique setup super long pre-ganglionic fibers Which are not the norm right for for our sympathetic trunk Let's see. Let's see. And so that's pretty cool We will find the neurons in here are actually from not surprisingly hopefully neural crest cells Okay I want you to know this meaning it's going to be on the exam, right? That's how I make sure you know things um mass activation This means when our sympathetic nervous system is going to be at its height in terms of activity, right? So we are going to simultaneously spark innervation of Many many many organs in our body right through the pathways we just talked about This is going to occur in an emergency crisis situation, right so we could have sympathetic innervation occur Kind of separately individually, but when we have this really extreme situations mass activation allows us to respond In this way, right? In this way, right? So we're going to have numerous things going on We are going to have our adrenaline being pumped into Uh the body via this um this gland the adrenal gland is going to have a vast vascular network so we can get a If we have um, we can get adrenaline into the body system really quickly through our blood supply Um, and it's going to cause all these things at once right heightened sense of alertness Increased heart rate. So then big pupils for this one blood pressure goes up respiration increases breathing rate increases And our pupils are going to dilate. There we go. Um, so All this happens at once through this really fast acting thing and it's pretty cool and then I have this Um better. Um, I think uh moving meme. I don't know gif. That's what i'm looking for gif here I think this ostrich head head is much better Yeah Okay histology and development. I know it's your favorite, but don't worry. It's a lot of what we already talked about Okay, so histology. Um, we are looking at a sympathetic ganglion Meaning it's either those pre or paravertebral ganglia. Meaning it's either those pre or paravertebral ganglia. We've seen these before we know what neurons look like, right? We know that they're really big We know what the nuclei look like right so we can find these really big really big structures really big cells So these are going to be the neurons Um, and then uh in addition to our neurons We're going to have we're going to look and identify these little cells that sit along The periphery of the neuronal cell body which are going to be satellite cells These are going to be there to kind of help take care of and support Our neurons, right? So if they're dark staining on the periphery of these neurons, it is a satellite cell We have also looked at nerves before right? We know what nerves look like we know that we're going to look for kind of stringy like structures At least if you're looking at a longitudinal section And we are going to look for the nuclei which are these dark staining elongated structures, right? Specifically these are going to be our neural lemocytes our Schwann cells because these are what wrap around a nerve So here's our nerve and they're going to go around And we're going to be able to see The the nuclei of these cells in this way, right? The the nuclei of these cells in this way, right? So here are our neural lemocytes Schwann cells In this specific type of ganglia, we're going to find there's neurons. You can even see how big they are all over the place More towards the center and our nervous tissue our axons More on the periphery Okay Development of the sympathetic nervous system Again, we've kind of seen this view before but we've added a few more structures. So here's our neural tube right here Our neural crest cells have come off that neural tube to create the peripheral nervous system Here it's setting up to become really our dorsal root ganglia but we also will have our The cells that create our other ganglias now, we know that there are our cranial ganglia, we know that we have Our prevertebral and paravertebral ganglia as well, right? So they are going to migrate to their location So on either side of the aorta for para or in front of the aorta for prevertebral And as they go and we'll have the same process where we'll have our neuronal cell bodies Grow out their axonal axon extensions to meet these structures And then our cell bodies growing within these structures here are going to grow to Meet your effector organs, right? So this is going to be our developing GI tract we have an extensive autonomic nervous system there So you can see those fibers going to that location, right? So in the same way that we talked about our somites we have our axons go out of our neural crest cells or out of our neural tube to join up with dermatome Myotome not the sclerotome as they migrate to form muscles in the body. We will see a similar pattern from our autonomic nervous system and so specifically we're looking really at the sympathetic nervous system here This is going to start really during week five, right? So we've already folded we can now see that inside the body space the intra embryonic coelom body cavity now okay, if we Go a little bit further in development. So week five plus that's when we will see those axons growing out of the neuronal cell bodies And really what they're going to do is they're going to grow along that pathway that we've already talked about this entire lecture, right so we are going to have those neuronal cell bodies grow out their axons Going to go out that anterior ramus our anterior root assuming we're looking just at motor here through that spinal nerve Onto our sympathetic trunk via that white ramus is going to travel before Or stay there before either it's going to go to the skin or the thoracic organs We're going to synapse in a sympathetic trunk ganglia Before we exit if it's to the skin we're going to go off Via that gray ramus joined with the spinal nerves our anterior posterior rhema to where we need to go or if it's a thoracic Organ we're going to get on that white ramus these they're going to grow into that white ramus and then Synapse at the right level and leave Growing out those and creating those splenchnic nerves to the organs, right? And then if we're in the abdominal pelvic organ stuff We're going to get on travel on a sympathetic trunk or leave immediately go to our pre vertebral ganglia That's where we find our set and we're going to connect to our developing Post-ganglionic neurons which are sending and growing its axons out to the effector organ so this all just says The axons are going to grow in the pathway that we have already talked about If it was sensory, we will get to sensory it will come in Via these splenchnic nerves, for example Synapse come on in we're going to go out on that gray ramus There post- ganglionic fibers and go through the posterior structures if it's sensory, right? So we'll talk about sensory later on a little bit All right. That's all I got for you. I know this is hard and it is a lot Come talk to me during office hours. Ask questions so we can talk this over. All right. Good luck, everybody