hey everyone this is the first video in a series of videos on the spine and the spinal cord the spine includes all of these vertebrae it also includes the spinal cord which is this nervous tissue that runs from the brain up here down through those vertebrae and it's got all these spinal nerves that Branch out of the sides that spinal cord and spinal nerves along with some cranial nerves that come directly from the brain are going to be the main way that your brain sends signals to the rest your body to control your movements those nerves are also a way that your brain is going to get information so whenever you feel something signals will travel up through those spinal nerves up through the spinal cord and then to the brain for this video specifically we're going to cover the different regions of the spinal cord and the spinal nerves that come from those as well as talk a little bit about what does each of those nerves control or do also I myself have a spinal cord injury so this topic is particularly of interest to me so I'll include some details about my own injury throughout this series as well all right without further Ado let's jump to the Whiteboard and get started we're going to start with an outline of the human body at the top of that we're going to draw a picture of the brain and the brain of course is where the signals that we use to control the body are going to come from it's also where the sensory input that comes from the rest of the body is going to travel up to also check out my brain videos if you want to know more about the brain and descending down from the brain is the spinal cord now I'm not going to draw the whole spinal cord all at once but we're going to start with the top section and then work our way down so this first section at the top and the superior section is called the cervical region of the spinal cord there's going to be eight cervical nerves that extend out to the sides of that section and the naming convention for these nerves is pretty easy we've got C1 here at the top there's eight of those so to go C1 C2 C3 all the way down to C8 at the bottom of that section now on this side of my diagram I'm just going to label the names of the nerves and then over here we're going to talk about what they do but over here on the other side I'm going to draw a little bit more anatomically correct of what those nerves look like as they kind of Branch out from the spinal cord so in the cervical region over here a lot of these nerves are going to kind of twist around they'll Branch out they'll converge they're going to form the section called the brachial plexus brachial is always referring to the arm and so these nerves are going to extend down the arm and we use the term plexus anytime we've got a group of these nerves that kind of Branch around with each other so we've got the brachial plexus there all right so what do these nerves do before we get into that we need to learn a few more terms here the first of which is somatic the somatic division of the nervous system is going to be our sensory and motor divisions motor is whenever we have a signal coming from the brain and going out to the body such as whenever I tell my hand to move that would be a somatic action potential traveling from my brain down my spinal cord out through those cervical nerves and then to the muscles in my arm and hand to cause all that movement to happen and sensory would be like if I touch something and that signal from that touch sensation travels through a nerve through the cervical nerves there up through the spinal cord and then up into my brain where my brain can interpret that signal the idea that kind of Unites those under this umbrella of somatic is they're both conscious things so if I'm touching or feeling something I can do that consciously I can think about whatever I'm touching as well as my motor signals whenever I'm moving around I'm consciously controlling my movements things that are controlled by this that we don't consciously think about we call those autonomic and I think about this term autonomic kind of like automatic it sort of automatically happening without me having conscious thoughts about it it's still controlled by my brain my brain is sending signals back and forth through different parts of my body to control things that I'm not actively thinking about an example that would be like digestion I can't really think about like oh let me tell my intestines to do stuff to digest the food or to absorb the nutrients that's happening and it's regulated autonomically by the brain so for each of these sections of spinal nerves that we look at we're going to talk about what does it do in the somatic division which is where we consciously have thought about what we're doing and then what does it do in the autonomic division the stuff that we're not consciously thinking about the stuff happening automatically also a quick note right here the somatic does include sensory and motor but all the information I'm giving you here is really based on the motor division control and I'm also not getting super precise with this I'm going to give you kind of nerve regions and sections of the different nerves but if you're really going in depth and you want to know exactly what C7 controls specifically that I'm not going to get quite to that level of detail in this video alright with all that out the way let's talk about the cervical nerves all of these cervical nerves see one through eight they're going to control movements of the neck and utilize those cervical nerves cervical just means round or circular and so think about the neck being this like kind of circle or cylinder there that's where we get that term cervical for for the neck and if you just look at the location of those nerves right they they're right there at the neck so it makes sense that those are going to control neck movements what about your like facial movements most of that's going to be controlled by cranial nerves which we're not going to get into this video that'll be a separate video so all of those nerves are going to be involved in regulating the neck specifically C3 through five is going to help control the diaphragm so anytime that you're breathing or singing use your diaphragm c335 is going to control the diaphragm which is going to regulate your breathing your lungs aren't the ones actually controlling the breathing that's that's your diaphragm and intercostal muscles between the ribs and then nerve C5 through 8 are going to help control the shoulder the arm and some of the hand those are going to be the lower nerves in the cervical region and those can be the ones that form this brachial plexus that are going to go down into to the arm and the Hand in that region now let's talk a little bit about spinal cord injury what if somebody had a spinal cord injury in this neck area well generally whenever there's a spinal cord injury somebody's going to lose function of things that are below the region where the damage is usually reflexes will still work down in the lower regions I'll get into why that is in another video but signals won't be able to get all the way up to the brain or from the brain down to any region that are below that injury site I'm also talking about what's called a complete spinal cord injury so there are incomplete spinal cord injuries too where some signals can pass through but not all but in general I'm talking about complete spinal cord injuries where no signals can pass by so if somebody had a complete spinal cord injury let's say at the C5 region then they would have some net control um they would have some diaphragm control so they could control their breathing but then they would have a lot of loss of function in the shoulder arm hand and kind of everywhere below that part of the body if the injury were higher like up in the C1 region then they would have trouble breathing on their own and so they might have to have some assistive device to help them breathe because they wouldn't have brain control over their diet diaphragm and regulating their breathing my spinal cord injury is going to be a lot lower down in the lumbar region so we'll get to that a little bit more later all right what about autonomic control well it turns out that the cervical nerves don't have any autonomic functions so they're not going to be regulating anything that happens sort of automatically or involuntarily all right for organization on my diagram here when we get to the next regions I've got these green lines to kind of separate it out it'll make more sense as we go through it all right the next region just inferior or below the cervical is going to be the thoracic region of the spinal cord and that's going to include 12 thoracic nerves so the nerve immediately inferior to C8 is going to be T1 or thoracic nerve number one that's going to number all the way down T1 T2 T3 all the way down to T12 at the very bottom of the thoracic region what really distinguishes these from the spherical nerves above and the lumbar nerves below is that each of these corresponds with the vertebrae that's going to be connected to a rib so we have 12 ribs if we're going to have 12 thoracic vertebrae these thoracic nerves aren't forming any sort of a plexus but they're going to all of these parts of the kind of the Torso right here so we had cervical on the neck remember cervical means round and then below that we have thoracic just like the thoracic cavity here or I think of thoracic part I mean Jurassic Park if you think about dinosaurs and their skeletons you see all those ribs and stuff the DraStic sounds like thoracic the ribs this corresponds with the ribs it's a bit of a stretch but if it helps you remember thoracic great the DraStic nerves I mean thoracic nerves all right what do those thoracic nerves do so t one through six are going to control the intercostal muscles which are going to be the muscles between your ribs those muscles help with Breathing by kind of pulling your ribs out like this and other regions of the trunk above the waist which makes sense T1 through six they're right in that region they're going to kind of Branch down they're going to control all that trunk region the rest of those thoracic nerves are going to be controlling your abdominal muscles so the muscles you use whenever you do sit-ups or for me whenever I'm like sitting up straight in my wheelchair I'm using those thoracic nerves to control my abdominal muscles to keep me sitting up now my balance setting up isn't great that's because there's other muscles that I don't have control of like muscles on my leg and that sort of thing but if somebody has a spinal cord injury somewhere in that thoracic region that's going to limit their trunk muscles and abdominal muscles so they're gonna have a hard time kind of sitting up straight on their own without some back support or other support to help them sit now if you think about where those thoracic nerves are located all of this region right here of your torso is where all of your internal organs are like your lungs and heart and liver and spleen and pancreas and intestines most of those are organs that we don't voluntarily control so we need some autonomic or automatic control of those regions so this is going to be where the sympathetic stress response is taking place or it's regulated by the body the sympathetic stimulation is your stress response so anytime you're in a stressful situation all these changes happen in the body that could be anything from your heart beating faster your lungs breathing harder your digestive system becoming less active because if you're in danger you don't need to be focused on absorbing nutrients and food you need to be focused on getting to safety so all of that stress response is going to be regulated by those thoracic nerves which are sending signals to those organs down in here to prioritize safety over kind of your rest and digest response so thoracic nerves for sympathetic stimulation or stress response now just inferior to the thoracic is going to be the lumbar section of the spinal cord the lumbar is going to have five different nerves that are extending out from it so we've got L1 there at the top or Superior side of that and then L5 down at the inferior or lower part of that this section is going to start to form a plexus over here so as those nerves extend out they're going to branch and converge and form this kind of web of nerve tissue we're going to call that the lumbar plexus you also notice on the diagram that in the cervical and the thoracic regions we had sort of one tube that's forming the spinal cord but as we get down to the lumbar that tube starts to Branch out and we don't have just this single tube going down from the spinal cord it's going to be this kind of horse's tail like looking thing in fact that's how it got its name it's called the Kata equina which just means horsetail in Latin so that Kata Aquinas where that single tube of the spinal cord kind of branches and becomes sort of this uh this mess of smaller tubes that are forming that caudi equina now the lumbar also involved in that sympathetic stimulation or stress response so I said thoracic it's really going to be the thoracic and the lumbar both of those are going to be controlling our stress response so whenever we get stressed out we see something that's going to cause us to maybe be in danger or we got a big test coming up or a conversation that we're nervous about and our body goes in that stress response signals will go from the brain down through the spinal cord out through both the thoracic nerves and the lumbar nerves in order to control a regular regulate that sympathetic stimulation our stress response now there's going to be some overlap with the lumbar and our next section which is the sacral when it comes to the somatic the sensory and the motor division here so I'm going to go and talk about that sacral section and then we'll talk about what the lumbar and sacral section does in the somatic division so here we've got the sacral Division and the soccer division is going to have five nerves so we have S1 at the top or Superior section an S5 down there in the inferior or bottom section so we've got the lumbar and the lower back region and then we've got the sacral down below that I can turn around here and demonstrate this a little bit we got the cervical and we've got the thoracic down here and then we've got the lumbars the lower back and then the sacral is going to be kind of down at the very bottom or base of the spine all right so what are those Lumbar and sacral nerves control well L1 through S5 and that's going to be really that whole region right there is going to be controlling your hips your legs and your feet I didn't separate it out into just the lumbar and just the sacral because there's a lot of overlap in which of those control those different parts of the hips and legs and feet so in this video we're not going to go into all the specifics of that but that hopefully makes some sense if you just think about where those are located right those are at the very end there so your hips are going to be right in that area and then your legs and feet are down from there and so all of these Lumbar and stock Corners they're going to Branch out and they're going to go down into the hip and the leg area to control all that those sacral nerves specifically are going to be involved in something else not the sympathetic but the parasympathetic stimulation and that's going to be in the autonomic this is again the automatic or involuntarily controlled parts of the body and to get a little bit more specific with that this is going to be parasympathetic stimulation of the bladder which is going to be contraction of the bladder as well as reproductive organs so when you're more relaxed that's going to cause your bladder to contract it's also going to cause increased blood flow to the reproductive organs if you're stressed out the reproductive system doesn't work as well it's also harder to to urinate if you're stressed out now that's obviously just a couple parts of parasympathetic stimulation and we're running out of sections of the spinal cord here so where does the parasympathetic stimulation occur for the rest of the parts of the body like how's the brain going to tell the heart to slow down whenever you're in your parasympathetic or rest and digest response well that's all going to take place through the cranial nerves and I said we aren't going to talk about the cranial nerves in here we're not going to get into the specifics but I really want to kind of finish this diagram out and talk about where parasympathetic response occurs so that's going to be in your cranial nerves and you've got cranial nerves are going to go down kind of through the neck directly from the brain so not through the spinal cord directly from the brain down to some of those organs down in here to do that parasympathetic response or the rest and digest response that would be things like slowing down your heart and your lungs but also increasing your digestion telling the pancreas for example to release more digestive enzymes all right we have one more nerve to talk about in the spinal cord and that's going to be the coccygeal nerve that coccyx is your tailbone and so the coccygeal nerve is going to be a nerve that kind of comes out by that tailbone at the very base of the spine that coccygeal nerve doesn't really have any motor control and like I said this is all motor stuff right here so I did want to include a little bit about it's going to be tailbone sensation so the sensation on your tailbone that's going to be from the coccygeal nerve and to finish off the diagram over here on this side let's draw out where those nerves Branch down and kind of where they go you can see here there's another sort of web-like section of nervous tissue and so up here we have the lumbar plexus down here we're going to have the sacral plexus again it's just another kind of web-like system of nerves that kind of branch in and out of each other so we call it a plexus this one's the sacral plexus those nerves are the sacral plexus tend to converge down right here and form a nerve that's going to go down through the leg to regulate movement and sensation in the legs and feet and Toes now I said I was going to talk a little bit more about my disability so my disability is a complete spinal cord injury of the L2 and L3 vertebrae or the nerve that's right there between those and so my injury is going to be right in here so what does that mean for me well any of the stuff that's below that is going to be stuff that my brain doesn't regulate in kind of the normal way so for example all the muscles of my hips my legs and my feet those muscles still exist and they can can still contract but I can't consciously control them I can't think about my feet moving and then make that happen because the signal is going to travel down from my brain through my spinal cord it's going to get to that injury and that L2 L3 section right there and that signal can't go any farther so the muscles in my legs and my feet and my hips and all that they never get the signal to go ahead and contract I still have reflexes though so if I were to like I don't know poke my leg with a needle or something the muscles in my leg would still start to contract like that I still have the reflex because the signal can travel from my skin and my leg to the spinal cord and then back out to a muscle I just wouldn't feel the pain from that because that signal can't make it up the spinal cord to my brain and I'll go a lot more in depth with that in a later video all right let's do a quick recap here of all the stuff so we have five sections of the spinal cord starting at the top we have the cervical the thoracic the lumbar the sacral and the coccygeal the cervical has eight the thoracic 12 the lumbar 5 the sacral 5 and the coxane one for a total of 31 pairs of nerves those are pairs of nerves right because we have one come out the left and one come out the right for each of those sections I really like how the numbers kind of work out nice and neat the eight at the top plus 12 gives us a nice round 20. and then we have five and five giving us a nice round 30 and then there's kind of one at the end so eight twelve five five one those nerves are going to form several plexuses Plexi plexuses we have the brachial plexus at the top then we have the lumbar plexus and the sacral plexus we also have the Kata equina which is going to be where the tube of the spinal cord starts to kind of split and form this horse tail-like section in the spine for somatic control specifically motor our cervical nerves are going to control things like the neck the diaphragm for breathing and then our shoulder arm and hands the thoracic is going to control everything in our kind of torso area so our intercostal or rib muscles our trunk everywhere above the waist and our abdominals down here the lumbar and the sacral are going to control movement of our hips our legs and our feet basically the whole lower body and the coccygeal nerve has no motor control but it does deal with some tailbone sensation that's all the somatic control and then we also have the autonomic division so we've got cranial nerves which are going to control our rest and digest system for most of the body we'll cover all that in another cranial nerve video later on our sacral nerves are going to be involved in parasympathetic control as well and that's going to be specifically of the bladder causing it to contract and the reproductive organs causing increased flow to the reproductive organs so if you're really stressed out it's gonna be harder to do reproductive organ kind of stuff and then finally our thoracic and Lumbar sections those are going to be involved in our sympathetic stimulation so whenever we're engaged in a stress response signals will come through those thoracic nerves and Lumbar nerves to the organs of our body right here in order to increase our stress response so like our heart beating fast our lungs breathing faster but also suppressing our digestive system and things like that finally if you're trying to learn all this stuff and really remember it the only way to do that is to practice yourself all right here we have a blank diagram take a minute pause the video see if you can name all of the sections the number of nerves in each section the other anatomical parts of this as well as what each section of the spinal cord controls or regulates we have the cervical which is eight nerves we have the thoracic of 12 nerves we have the lumbar region with five nerves the sacral with five nerves and the coccygeal nerve the cervical is going to control all of those regions neck diaphragm shoulder arm hand thoracic will control the trunk and the ribs and the abdominals we have the lumbar and sacral which is going to control the hips legs and feet coccygeal for tailbone sensation we have cranial nerves controlling the parasympathetic response cervical doesn't do anything with the autonomic we have the thoracic with sympathetic stimulation or stress response and the sacral for parasympathetic stimulation of the bladder and reproductive organs and then some anatomical regions we talked about the brachial plexus cada equina lumbar plexus and sacroplexus like I said this is just the first video in a series of videos on the spine and spinal cord and cranial nerves and kind of all that nervous system stuff and I already have videos on the brain and neuron and action potential and synapses and a bunch of other topics on the nervous system so if you click the video link over here or over there that'll take you to a playlist of nervous system videos alright I'll catch you in the next video