the second set of nerves that we're going to be looking at after the cranial nerves are our spinal nerves so spinal nerves are the 31 pairs of nerves that emerge out of your spinal cord remember how your dorsal and ventral roots from your spinal cord merge with each other and when they merge with each other you form a spinal nerve so spinal nerves are really easy actually because they're going to be named according to their points of issue meaning if it emerges from your cervical vertebrae it's going to start with the letter c if it's thoracic vertebrae then it's going to be with the letter t if they come out of the lumbar vertebrae then they're going to have l and so all your spinal nerves are going to be b for both they're all two-way streets they have make they are mixed nerves and so with your spinal nerves there's going to be so many of them and so many branches that emerge out that we're just going to consider them and in networks this one's going to go by really fast because we're going to lump our spinal nerves together into plexuses plexus just means network we're going to go from our spinal cord and look at first our cervical plexus then our brachial plexus remember the cervical enlargement because you have you you have very large nerves that will emerge out to innervate your shoulders and upper limbs so you have a brachial plexus for that we have a lumbar plexus but we also have a sacral plexus and so we're going to break these things up one at a time starting with the cervical plexus so the cervical plexus is a small network of nerves they're only emerging out of c1 and c4 however they're super super important because not only do they innervate the muscles in the skin of your neck and shoulder but you also have one this little little bit right here this is your phrenic nerve it's going to go all the way down to your diaphragm your diaphragm is super important because it's a very important breathing muscle and so we definitely cannot break our necks if you break your neck and you damage the cervical plexus we can die because your diaphragm starts work stops working we become paralyzed so for the cervical plexus is going to come out of c1 to c4 so those are the points of issue but when it comes to their functions it remember that they're all mixed nerves they have both sensory and motor function so it innervates the muscles and skin of your neck and shoulders so can you feel your neck can you move your neck or your shoulders can you feel your shoulders or can you move your shoulders that means cervical plexus is working just fine but remember how i said that it may be a relative relatively small plexus but it's super super important it's incredibly important because of the phrenic nerve so i'm going to put big asterisks here so three asterisks meaning it's super important whenever you see anything with the term phrenic so phrenic artery phrenic vein phrenic nerve sophonic nerve it innervates your diaphragm and again this is why it's so dangerous to break your neck it's because you have a phrenic nerve right there that lets you breathe okay so the next network that we're going to look at so that's network number one your cervical plexus network number two is going to be your brachial plexus brachial plexus is going to emerge out of c5 and it's a little bit bigger it goes all the way out into your first thoracic so from c5 to t1 very right where your cervical enlargement is going to be at this is going to form your network of nerves that form the brachial plexus and this one's really easy because you already know what the term brachial means this innervates so some of it goes down to your shoulder some goes into thorax so not all so some of your thorax and upper limb all right so that's the brachial plexus let's go ahead and look at an image of that brachial plexus you can't miss these nerves because especially whenever you have nerves going down to the limbs your upper limbs versus lower limbs they're particularly big so your brachial plexus is a really big bundle of nerves see how they're going right under your clavicle over here into the axillary area your armpit area and you're going to then branch out that network to go down your humerus down your own end radius and all the way to the tips of your fingers and so all this is part of your brachial plexus some of it will go into the thorax but it's really mainly for your shoulders and for your arms i want to point out a little bit of feature over here i want to point out your ulnar nerve right here so ever since the beginning of time it's really annoying when this happens every time you hit this part of your elbow what happens so this is your funny bone there's nothing funny about that funny bone i don't know why they call it that but you're actually not hitting bone your ulnar nerve is really superficial so because it is superficial when you hit that part of your elbow the pain radiates it hurts a lot because you have struck the ulnar nerve so funny bone isn't so funny because it's actually the ulnar nerve that you are hurting okay so that's actually one of the branches that you have for the brachial plexus so now let's move on to our other plexuses so we have two out of our four plexuses and this next one is your lumbar fluxes so see how you have your lumbar vertebrae so emerging out of your lumbar vertebrae you're going to have a networks of networks of nerves that will travel anteriorly notice how some go through the obturator foramen over here remember that hole on the pelvis and eventually goes down your femur down your tibia all the way down that leg and so that lumbar plexus is going to be a network of nerves so let's take some notes down let me scroll down it's going to emerge out of l1 to l4 and its job is to provide provide supply so this is very specific it's very specific to anterior and la medial thigh so specifically just the front of the and the inside of the thigh and leg so why so specific it's because of where these nerves are traveling just the front of your leg and just the insides of your legs so who's going to take care of everything else everything else for the rest of your legs is actually taking care of your sacral plexus so this is just anterior medial and it's innervation this one is going to be much bigger so the sacral plexus is a really big group of nerves that are going to come out of l4 and out of your sacrum and so there are foramina or holes in the sql sacrum and these are the nerves coming out of it and so it's going to innervate everything else so innervates or you can say provide supply and don't forget these are mixed nerves so all spinal nerves are mixed so when we say supply it's for both feeling and movement of the muscles so it supplies feeling to you from your skin on your legs but it's also going to be for movement of these leg muscles and so this is for the rest supply for the rest of the lower limb so there's one special feature i want to point out over here and it's the biggest nerve that we have the biggest nerve is going to be our sciatic nerve so the sciatic nerve is really big and it's going to um it can cause a lot of people a lot of discomfort and problems and they'll start talking about their sciatica or their sciatic pain and so the sciatic nerve is super important because it innervates the entire lower limbs entire lower limb and so except of course the anterior and medial part because that's your lumbar plexus but everything else your sciatic nerve takes care of that and so when someone's talking about butt pain or the back of the leg pain sometimes it happens during pregnancy sometimes it's because of injury sometimes because it happens with old age they're actually complaining about sciatica so let's look at our lumbar versus our sciatic or lumbar versus our sacral plexus so lumber is anterior medial so it traverses anteriorly and on the medial side on the inside of the thigh and the leg your sacral plexus on the other hand is at the back so look very closely at the picture over here on the left see how so let's back up from here we're looking at the anterior view this is the front of the pelvis the circle plexus this is a posterior view this is the back of the pelvis so all these nerves that are exiting out of the sacrum and out of l4 this is part of your signal plexus see how you have this very large sciatic nerve that goes from the gluteal region down the back of the femoral region all the way down to the back of the legs so the super big sciatic nerve can cause people a lot of problems because injury can happen inflammation can happen and it's going to cause pain to these parts of the body so that's it that was really quick we are done with our four major plexuses