I engineers in this video we're going to talk about the sacral plexus so we already talked about the cervical plexus we talked about the brachial plexus we talked about the lumbar plexus if you haven't seen those videos at least go back and watch the lumbar plexus because it's going to feed into the sacr plexus so first off if we look here the sacral plexus is actually going to be coming from about L4 L5 it's also going to go down to S1 S2 S3 S4 S5 and coxial one all right so this is a pretty big plexus one of the main nerves that are coming off of the sacral plexus is actually going to be a very very important one called the sciatic nerve and we'll talk about the clinical correlation with that okay so what happens here is we're actually going to have the first nerve here let's see we're actually going to have let's take here and we'll have a line here for L4 then we'll have a line here for L5 and we'll put a line here for S1 now what happens is there's a nerve that's actually going to pick up some branches from L4 L5 and S1 so L4 L5 and S1 let's draw this guy let's do this one in a nice bluish color here so if we start here let's say we start about right here and we're going to take these fibers up so if we have the fibers from S1 we're going to take some fibers from what else L5 we're going to pick up some other fibers from L4 so we're going to have L4 L5 and S1 this is actually going to form a very very important nerve that's going to supply the glutitis med uh medius and the glutitis Minimus this is actually called The Superior Glu nerve so this nerve is primarily going to be that of motor nerve it's primarily a motor nerve so Superior Glu nerve and the superior Glu nerve is important because what do we say it supplies IT Supplies two main muscles so one of the muscles is actually going to be the glutitis medius and the other one is going to be the glutitis Minimus and these are important muscles because they're abductors abductors so they pull the actual hip away right so they're abductors so gluteus medius and glutitis Minimus okay so that's the superior glal nerve the inferior Glu nerve is actually going to be just one branch down so now it's going to take fibers from L5 it's going to pick up fibers from S1 and it's going to pick up fib from S2 so what is this nerve right here let's actually have him coming up now so let's have a branch here let's say this is our S2 here and if we have these fibers coming up here so we're going to have fibers here from S2 we're going to have fibers here from S1 and we're going to pick up some fibers from L5 here all right and then also you're going to have fibers from L5 if we have this right here this is going to form What's called the inferior glutalor Glu nerve and this is the one that supplies the the Big Mama this is the glutitis Maximus so this is going to supply the glutitis Maximus and the glutitis Maximus is important because it provides two functions one of the functions is it's going to play a role with an extension at the hip and it's going to play a role with lateral rotation at or external rotation of the hip okay so two big ones right there again Superior glal nerve inferior glal nerve now there's another one it actually comes from L5 S1 and S2 and it's actually going to come from the ventral division so it's actually going to be a ventral division let's do this one in red color let's bring here we're going to bring it off this way so L5 where we're going to have a branch here from L5 you're going to have a branch here from S1 and it's even going to Traverse downwards here and it's going to pick up another Branch here from S2 so what are we going to have we're going to have L5 we're going to have S1 and we're going to have S2 this is a pretty cool nerve this nerve is actually going to be called the operator interus nerve don't get this confused with the opat nerve that came off the lumbar plexus right so this is going to be the opter internis nerve or they call it the nerve to opter internis but that's kind of deceiving and the reason why is the opter Andis nerve not only does it Supply the opter Andis but it supplies another muscle called The Superior GIS so it supplies two muscles one is actually going to be the superior GIS and the other one is actually going to be the operator internis why is this important because these are also deep muscles they provide lateral rotation of the hip or external rotation of the hip okay so that's going to be the opter internis nerve now there's going to be another one and this is actually going to be a posterior division so this was an anterior division now we're going to get a branch that's going to be supplying the posterior division it's actually going to be a posterior Division and this is going to be called the posterior cutaneous nerve now the posterior cutaneous nerve which is pretty much it's pretty easy to identify and you're also going to be able to know that it's actually going to be cutaneous so it's going to provide Sensations right and this is going to be picking up branches from S1 it's going to be picking up some fibers from S2 so it'll pick up some fibers from S2 and it'll pick up fibers from S3 so if you pick up fibers from S1 S2 and S3 let's actually bring this one a little bit up let's bring this one a little bit up so let's bring this one like this let's bring him up a little bit here and again what would the other Branch be here so we already have S1 S2 and there's going to be another Branch here which is going to be S3 okay this nerve is important because we already said what it is it's going to be called the posterior cutaneous nerve and the poster cutaneous nerve as you can already tell it's going to be having cutaneous sensation so it's primarily having cutaneous branches what does that mean so it's going to be picking up Sensations Sensations from where it's going to be picking up Sensations from you probably already can tell guys posterior what so it's going to pick up from the inferior booty cheek right so from the inferior buttock it's going to go down the posterior thigh it's going to provide Sensations to the posterior uh aspect of the knee right which is called the popal region it's going to Supply the skin around the tricep Sur area right the calf and it's going to supply the heel right so that's the posterior cutaneous nerve so Sensations from posterior inferior buttocks and it's going to supply posterior thigh posterior knee but we also call that the pop Lial region pop Lial region it's also going to supply the skin on the calf and right around the heel joint okay right around the skin around the heel joint okay so that's the poster cutaneous nerve now let's do the big mumbo jumbo right this is the big mama this one is going to be very very important let's do this one in a pinkish color this is going to be picking up a lot of branches okay so if we come for this one it's actually going to have a branch that's going to come from L4 so it's actually try to do this one very very particularly it's going to pick up branches from L4 it's going to pick up some branches from so we already showed L4 there we don't need to do that again it's going to pick up branches from L4 it's going to pick up some branches from L5 it's going to pick up some branches from S1 and it's going to pick up some branches from S2 it's going to move downwards here and it's going to pick up another branch and this branch is going to be from S3 let's actually show this just fusing into this one right so this is going to form into S3 so how many branches is this picked up it's picked up branches from L5 L4 S1 S2 and S3 this is the big mambo jumbo this guy is called the sciatic nerve okay so this is called the sciatic nerve now the sciatic nerve is extremely extremely important nerve but here's what happens you get to around the knee right around the knee joint just proximal to the knee joint it's going to get ready to split and what happens is it splits and goes and provides a anterior Division and it goes and supplies a posterior division okay all right so now we have the tibial nerve right so we're going to have a division here so the sciatic nerve is actually going to divide it's going to have two divisions it's going to give off a posterior Division and an anterior division now the anterior division you're going to have an anterior Division and then you're going to have a posterior division of the sciatic nerve right around the actual knee joint right now the anterior division of the side IC nerve is actually going to be the tibial nerve okay this is going to be the tibial nerve and it's going to have a lot of cutaneous and Motor Supply the post tier division is going to be What's called the common fibular nerve and this is also going to have a decent amount of cutaneous and Motor Supply so for the tibial nerve it's supplies a lot of different things right so let's talk about the cutaneous Supply and let's talk about the motor supply so what is the aneous Supply well pretty straightforward for this one the tibial nerve is going to supply pretty much the entire posterior leg so it's going to supply the posterior thigh it's also going to supply a little bit of the popal region also it's going to supply the cutaneous sensation over the actual calf and the cutaneous sensation on the actual sole of the foot so if we talk about the tibial nerve the cutaneously going to supplies we could really just say posterior leg limb right and the sole of the foot so it supplies a decent amount of cutaneous sensation that's why if there is any type of actual compression of the sciatic nerve maybe beyond the point where it actually divides affecting the tibial nerve you can actually have a lot of paresthesia right pain numbness tingling Burning Sensations because this actual tibial nerve is applying a large amount of cutaneous Supply that's why sciatica can be actually so painful sometimes where there's actually compression of the proximal part of the sciatic nerve affecting both divisions we'll talk about that in a second okay then we're actually going to have the oh gosh darn it we have the motor supply so we have the motor supply of the actual tibial nerve and the motor supply he has a he has a decent amount of Motor Supply okay so what are the motor supplies of this nerve it can supply the hamstring muscles so he's going to be one of the primary providers of the hamstring muscles but we have to be very very careful right what are the hamstring muscles you know there's actually going to be the biceps for moris but here's the thing he does Supply the biceps from mors but he does not supply the actual short head he only supplies the long head so he'll Supply the long head not the short head that'll be picked up by the common fibular nerve then it's also going to supply the semi tendonosis the semit tendonosis it'll also Supply the semi membros it'll Supply a little bit of the adductor Magnus so it'll Supply a small portion of the adductor Magnus it'll even Supply the popus so it'll Supply the popus muscle it'll Supply the plantaris man he supplies a lot of muscles right he'll Supply the tibialis post interior he'll Supply the flexor digitorum longus he'll even Supply the flexer hsus longus and we could even keep going he supplies the triceps Sur which is made up of the gastr nemus gastr nemus and it's also going to supply the Solus so you know the gastro nemus there's the medial and the lateral head and it plays a role with implantar flection right and it also supplies some of the intrinsic muscles of the foot intrinsic muscles of the foot so he does a brag and Bol load right a lot of stuff this guy does that's why if the tibial nerve is by some reason if you have sciatica and you're compressing the actual either the proximal part of the sciatic nerve the distal part like the anterior division you could have paresthesia within the posterior aspect of the entire leg right so pain numbness tingling Burning Sensations within the aspect even at the sole of the foot you also would have a hard time in all of these functions what are the what are the functions of the hamstring muscles they play a role within primarily extension at the hip and they play a role within flexion at the knee that requires a lot a lot of activities require that the aductor Magnus is playing a role within adduction the hip the pop lus is playing a role within flexion I'm all right the plantars plays a role with in plantar flexion tibialis posterior has many many functions you get the point if these muscles are affected you would have a very very tough time carrying out daily activities all right so now the other branch of the static nerve the post tior division is going to be the common FIB nerve the common fibular nerve let's actually do this one in in a bluish color here the common fibular nerve actually is going to have two branches also right it's going to have a cutaneous Supply and it's going to have a motor supply all right so for the motor component of the actual posterior division of the actual common FIB nerve what would it actually Supply it's going to supply the other what it's going to supply the short head of the biceps forus so it's going to supply the biceps forus primarily that of the short head okay what else would it Supply it will also Supply not just the biceps from Mor short head but it will supply the fibularis brevis so it'll Supply the fibularis brevis and the fibularis longest these are very very important everters of the ankle so they perform ersion of the ankle it's also going to supply the extensor hsus longus it'll also Supply if we even keep going it could Supply the extensor digor longus and it can even Supply the tibialis anterior so this is also going to be a really really really important nerve also because look what it can actually supply supplies a muscle that plays a role within extension at the hip it also plays a role within flexion at the knee this is the everter of the ankle this plays a role with an extending the actual big big daddy toe right and El is also going to be performing what it can perform uh dorsy flexion it can perform inversion at the ankle it can extend the digits and this also can do inversion and dorsy flexion of the ankle so provides a lot now common fibular nerve is actually going to be supplying what if we look at its cutaneous Supply this guy was supplying the posterior aspect now the fibular nerve is actually going to be providing cutaneous supply to the what to the lateral aspect of the leg so this cutaneous Supply is going to be to the lateral aspect effect of leg so it would provide what it would provide the lateral aspect of the thigh it would provide around the knee joint it would provide around the actual calf so this is going to have a lot of cutaneous Supply and again you can imagine if by some terrible chance the sciatic nerve is compressed maybe at the proximal points it would affect the anterior division of the sciatic nerve and it would affect the posterior division of the sciatic nerve and if that is the case look at the amount of things that could happen what can actually be one of the reasons in which the sciatic nerve is compressed most common cause of that is going to be some type of herniated disc so some type of herniated disc and we talk about this a little bit within the lumbar plexus if that nucleus pulsus right is actually compressing the sciatic nerve right if it's compressing the sciatic nerve so some part of the lumbar region what part of the re what part of the actual um uh spinal cord could actually be compressing the stic nerve any point in which there's L4 L5 S1 S2 and S three but to be very very particular the common fibular nerve is really only getting its branches from L it's actually only getting its branches from l u L4 all the way to S2 and the anterior division is getting from L5 all the way to S3 so in this case really if there is any type of compression on the S3 it would have more of an effect on the actual tibial nerve and less effect on the actual common fibula nerve okay so that's that guy and again any type of situation in which there's a herniated disc it can compress the sciatic nerve can cause sciatica an extreme uh basically they Define as like a shooting sharp pain that's running down the actual uh what it will run down the actual posterior and more of the lateral aspect of the leg all the way down okay so that's a terrible terrible thing all right and obviously then the only way to treat this is basically rest maybe non-steroidal anti-inflammatory drugs Maybe Physical Therapy sometimes they might even have to go in there and do some type of surgery to alleviate some of the pressure and the stress on that actual nerve all right cool deal let's do the another one so another one is actually going to be picking up branches from S2 and S1 so let's do this one let's do this one in this actual maroonish color here so if we take this one here this is going to be an important one because this is actually going to be for the this is going to be a post tier division of the sacral plexus so this post tier division of the sacr plexus this is actually going to be called the nerve to piriformis and this one's pretty easy and again what division would this be this would be a posterior division of the sacr plexus so this is going to supply the Nerf to parformance and obviously you know what it's going to be doing it's going to be supplying the perous Nerf I'm sorry perous muscle which is a lateral Rotator of the hip all right sweet deal now let's do another one let's do this in this doooo brown color here okay so now this is another super important one here let's actually bring this guy out here this is going to be picking up branches from what it's going to be picking up branches from S2 it's going to be picking up branches from S3 and it's going to be picking up branches from S4 let's bring this one upward so we can combine it with this guy here so let's actually bring this one here and if we have S4 moving up here it's going to pick up what fibers from S3 so it's going to pick up fibers from S3 and then what it's going to Traverse upwards and pick up some fibers from S2 and it is going to be a very very important nerve and this is actually going to be called the pudendal nerve this is going to be called the pudendal nerve pudendal nerve the pudendal nerve is important too right because it's actually going to have a lot of Supply a lot of different types of structures that it can supply so if we look at it in Motor Supply so let's actually look at in the aspect of a motor supply so motorwise it's actually going to supply the external anal sphincter right the structure that's basically helping you from crapping your pants right so it's going to supply the external anal sphincter this guy's pretty good to us right because not only is he provid that but he's also helping us to prevent us from peeing our pants too so what else would he be supplying he'd also be supplying the external your rethal shter so bless up for the pudendal nerve right man because that guy he saves our butt right literally now there's another branch of the pudendal nerve the other part of the pudendal nerve is going to be supplying a lot of cutaneous Supply so it does have a lot of cutaneous Supply we're going to have a video on dermatomes and myotomes so that we can have a better understanding clinically of why these nerves are so important because because it can be very very very very crucial to determining at what level of the spinal cord when you look at dermatomes could be affected and we'll talk about that a little bit later so the pudendal nerve right it's going to have Motor Supply to the external anal sphincter external urethal sphincter it's going to have cutaneous Supply to pretty much the entire perenium so entire pennium so for example if we talk about the male it would be providing information to the it picking up Sensations from the scrotum it' be picking up Sensations from around the actual penis it'd be picking up Sensations from around the anus it'd be picking up uh information from the skin in between the anus and the genitals which is called the perenium okay it's also going to be picking up information if we talk about for the female it be picking up from the clitoris it'd be picking up information from the labia majora and if we even keep going you can pick up information from the mons pubis so a lot of different structures that this bad boy can supply right so again easiest way to remember for the cutaneous Supply that is the of the pendal nerve is just remember it supplies most of the actual uh female and male perenium which is a lot of different structures which is enclosed within that area and motor to supply to the external anal shter and to the external urethal schinker okay one more plexus here okay and this right here should actually be L4 don't know why that put L5 there sorry guys again anterior division should be from L4 to S3 and this should be from L4 to S2 that's the only difference is that this is getting a a branch from S3 this is not getting a branch from S2 okay all right now for the last one here this one's pretty cool and this is going to be picking up branches from the Cox sigal one it's going to be picking up branches from S5 and it's going to be picking up some fibers from S4 this one's interesting because it's sometimes forgotten about and not talked about that often but it is it is clinically relevant sometimes to determine certain things like you know maybe a pilonidal cyst or Hox adenia this basically is going to be called the coxial plexus and the coxo plexus which is made up of S4 S5 and Cox one is going to supply it's mainly cutaneous Supply so it's going to supply the skin around what do you think the coxial region okay so it's going to supply the skin around the coxial region this is an important one because again if someone might have like a pylon idal cyst it might actually be picked up by the coxy plexus right so this any type of Sensations from the skin maybe some of the underlying uh tissue all right one other thing I want to mention here which is going to be important here is a law we'll talk about it a little bit more in dermatomes but it's called the Hilton's law it's not anything crazy all Hilton's law says is any muscle that crosses a joint all right so any muscle that's actually moving something at a joint for example if we take for example these hamstring muscles over here so the anterior division of the tibial nerve L4 to S3 it's going to supply what the hamstring muscles well most of these hamstring muscles are going to cross the actual back of the knee joint so because they cross the back of the knee joint this nerve the tibial nerve the motor supply is going to the muscles that cross the knee joint Hilton's law says that it'll also Supply the skin around that joint so again Hilton's law states that the the nerve if it is giving motor to supply to any muscle that is crossing a joint it's also going to supply the skin over that joint okay so that's an important concept and again it becomes very clinically important okay so what is Hilton's law state in general it says a nerve will supply skin around joint to any muscle that crosses that joint okay so that is Hilton's law okay so again with the sacral plexus L4 L5 S1 forms the superior glal nerve L5 S1 S2 forms the inferior glal nerve L4 L5 S1 S2 S3 forms the sciatic nerve but again it has two divisions anterior division which is only coming from L4 to S3 and posterior division which is only from L4 to S2 anterior tibial nerve look at all the massive buku amount of information that this guy is going to be supplying and then the actual common fi nerve also supplies a lot of different muscles also and has a lot of cutaneous Supply and then S2 S3 S4 is going to be the pudendal nerve S1 S2 S3 is the posterior cutaneous nerve and then off here we have a posterior division which is going to be S1 and S2 which is going to be the Nerf to Performance and then there's going to be a anterior division from L5 S1 and S2 this is going to be a anterior Division and this is going to be for the opat internis which supplies the superior glis and the opat internis and the last one is going to be S4 S5 and cox1 form the coxy plexus and then again we talked about clinical correlations with sciatica maybe due to most common cause being herniated discs right which is compressing any part of the actual sciatic nerve it's if it's compressing more proximal this person would probably not be able to really walk because of all the things that it's actually affecting they would have extreme uh pain numbness tangling within a certain aspect of the leg which is going to be the posterior and lateral aspect of of the actual entire leg all right engineers in this information we covered a lot of information about the sacral plexus I hope it all made sense I hope you guys did enjoy it if you guys did please hit the like button comment down in the comment section and please subscribe all right Engineers as always until next time