iein 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 lawnmower plexus because it's going to feed into the sacral 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 coccygeal 1 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 ok 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 care 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 and 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 off 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 gluteus medius and the gluteus minimus this is actually called the superior gluteal nerve so this nerve is primarily going to be that of mode nerve it's primarily a motor nerve so superior gluteal nerve and the superior gluteal nerve is important because what do we say it supplies this applies to main muscles so one of the muscles is actually going to be the gluteus medius and the other one is going to be the gluteus minimus and these are important muscles because they're abductors abductor so they pull the actual hip away rights with their abductors so who these medius and gluteus minimus okay that's a superior gluteal nerve the anterior gluteal 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 fibers from s2 so what is this nerve right here let's actually have him coming up now let's have a branch here let's say this is our s2 here and if we have these fibers coming up here so they 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 E inferior gluteal nerve so this is going to form what's called the inferior gluteal nerve and this is the one that supplies the the big momma this is the gluteus maximus so this is going to supply the gluteus maximus and the gluteus 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 that or external rotation of the hip okay so two big ones right there again superior gluteal nerve inferior gluteal 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 a red color let's bring here we're going to bring it off this way so l5 we're going to branch here from l5 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 you 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 D obturator internus nerve don't get this confused of the obturator nerve I came off the lumbar plexus right so this is going to be the obturator internus nerve or they call it the nerve to operator incurrence but that's kind of deceiving and the reason why is the obturator internus nerve not only does it supply the operator interest but it supplies another muscle called the superior melas so it supplies two muscles one is actually going to be the superior Comella and the other one is actually going to be the Optus why is this important because these are all so deep muscles they provide lateral rotation of the hip or external rotation of the hip okay so that's going to be the obturator internus 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 up a branch so that's going to be supplying the posterior division so actually 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 s too so it'll pick up some fibers from s2 and it will 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 off so let's bring this one like this bring them 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 posterior 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 priority can tell guys posterior what so it's going to pick up from the inferior blue cheek right so from the inferior buttocks it's going to go down the posterior thigh it's going to provide sensations to the posterior aspect of the knee right just a club popliteal region it's going to supply the skin around the triceps surae area right the calf and it's going to supply the heel all 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 popliteal region popliteal 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 posterior cutaneous nerve now let's do the big mumbo-jumbo right this is the big momma this one is going to be very very important let's do this one on 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 we already showed l4 that 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 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 mumbo jumbo this guy is called the sciatic nerve okay so this is called the sciatic nerve now the sciatic nerve is extremely extremely important Earth but here's what happens you get to around the knee right around the knee joint just to proximal to the knee joint it's going to get ready to split and what happens is it splits and goes and provide day anterior division and it goes in 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 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 joints right now the anterior division of the sciatic 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 posterior division is going to be what's called the common fibular nerve and this is also gonna have a decent amount of cutaneous and motor supply so for the tibial nerve it 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 cutaneous 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 a populated region also it's going to supply the you taenia sensation over the actual calf and the cutaneous sensation on the actual sole of the foot so we talked about the tibial nerve the cutaneous are 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 supplying a large amount of cutaneous supply that's why fatica 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 a second okay then we're actually going to have the exhaust on we have the motor supply so we have the motor supply of the actual tibial nerve and the motor supply he has that he has a decent amount of motor supply ok 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 femoris but here's the thing he does supply the biceps for Morris but he did not supply the actual short head he only supplies the long head so they'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 tendinosis the semi tendonosis it'll also supply the semi member gnosis it is supplied a little bit of e a dr. Magnus so this applies small portion of the adductor Magnus it'll even supply the popliteus sort of supply the popliteus muscle and you'll supply the plant Aras and he supplies a lot of muscles right he'll supply the tibialis posterior he'll supply the flexor digitorum longus he'll even supply the flexor pollicis longus and we can even keep going he supplies the triceps surae which is made up of the gastrocnemius - drock meaning yes and it's also going to supply the soleus to the gastrocnemius there's the medial and the lateral head it plays a role within plantar flexion right and it also supply some of the intrinsic muscles of the foot intrinsic muscles of the foot so he does a dragonboat load right a lot of stuff this guy does that's why if the tibial nerve is it by some reasons if you have sciatica and you're compressing the actual uses approximate art of the sciatic nerve or 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 aspect even at the sole of the foot you also would have a hard time in all these functions what are the what are the functions of the hamstring muscles they play a role with them primarily extension at the hip and they play a role within flexion at the knee that requires a lot of activities require that the adductor Magnus is were playing a role within adduction the hip the popliteus is playing a role within flexion to unset all right the plantar plays a role 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 - posterior division going to be the common fibular nerve the common fibular nerve let's actually do this one 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 post your division of the actual common fibular nerve what would actually supply it's going to supply the other what it's going to supply the short head of the biceps femoris so it's going to supply the biceps femoris primarily that on the short head okay what else would it supply it will also supply not just the biceps form or short head but I'll supply the fibularis brevis so supply the fibularis brevis and the fibularis longus these are very very important eavers of the ankle so they'd for one version of the ankle it's also going to supply the extensor hallucis longus it'll also supply edge weaving capability could supply the extensor digitorum 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 eve earner of the ankle this plays a role in extending the actual big big daddy tail right and else is also going to be performing what it can perform dorsiflexion it can perform inversion at the ankle it can extend the digits and this also can do inversion and dorsiflexion of the ankle so provides a lot now common fibular nerve is actually going to be supply and what if we look at its cutaneous supply this guy was supplying the posterior aspect now the fibular nerve is actually gonna be providing cutaneous supplied to be what to the lateral aspect of the leg so this cutaneous supply is going to be 2d lateral aspect of leg so it would provide what'll provide the lateral aspect of the thigh it would provide around the knee joint it would provide around the actual calf this is going to have a lot of cutaneous supply and again you can imagine if by some terrible chance the sciatic nerve is compressive at the proximal points it would affect the anterior division of the sciatic nerve and it would affect the posterior division of the site occur and if that is the case look at the amount of things that can 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 talked about this a little bit within the lumbar plexus if that nucleus papoul sense 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 read what part of the actual um spinal cord could actually be compressing the site of care of any point in which there's l4 l5 s1 s2 and s3 but to be very very particular the common fibular nerve is really only getting its branches from el it's actually only getting its branches from alpha 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 fibular nerve okay so that's that guy and again any type of situation in which there's a herniated disc it can compress the static nerve can classify Attica and extreme basically define it's like a shooting sharp pain that's running down the actual what it will run down the actual posterior and more of the lateral aspect of the leg all the way down okay that's a terrible terrible thing all right now obviously then the only way to treat this is basically rest may be 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 them another one so another one is actually going to 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 thee this is going to be a post here division of the sacral plexus so this posterior division of the sacral 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 will be a posterior division of the sacral plexus this is going to supply the nerve to performance and obviously you know what it's going to be doing it's going to be supplying each pair for master I'm sorry piriformis muscle which is a lateral rotators of the hip all right sweet deal now let's do another one let's do this in this due to brown color here okay so now this is another super important one here 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 upwards 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 as two and it is going to be a very very important nerve and this is actually gonna be called the pudendal nerve this is going to be called the pudendal nerve who dental 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 motor wise it's actually going to supply the external anal sphincter right the structure that's basically helping you from crap in 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 providing that but he's also helping us to prevent us from peeing our pants - so what else would he be supplying he'd also be supplying the external your wreath rosh winter so bless up for the pudendal nerve right man because that guy he saves our butt all 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 supplies so it does have a lot of cutaneous supply we're going to have a video on dermatomes and Miette ohm so that we can have a better understanding clinically of hawai these nerves are so important because it can be very very very very crucial to determining on 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 motor supply to the external anal sphincter external urethral sphincter it's going to have cutaneous supply to pretty much the entire perineum so the entire perineum so for example if we talk about the mail it will be providing information to the picking up sensations from the scrotum it'd be picking up sensations from around the actual penis it'd be picking up sensations from Romney Amos it'd be picking up information from the skin in between the anus and the genitals which is called the perineum okay it's also going to be picking up information if we talk about for the female be picking up from the clitoris it'd be picking up information from the lab eeeh 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 pudendal nerve is just remember it supplies most of the actual female and male perineum which is a lot of different structures which is enclosed with an area and motor to supply to the external anal sphincter and to the external your wreath ro shrinker okay one more plexus here okay and this right here should actually be l4 I 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 that's - that's the only difference is that this is getting a branch from that's three this is not getting a branch from us - 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 did you 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 the determining certain things like you know maybe a pilonidal cyst or ox edenia this basically is going to be called the coccygeal plexus and the coccidia plexus which is made up of s4 s5 and coccygeal one is going to supply it's mainly cutaneous supply so it's going to supply this skin around what do you think in the coccygeal region this was going to buy the skin around the in coccygeal region this is an important one because again if someone might-- how about like a pilonidal cyst it might actually be picked up by the coccidia plexus right so this any type of sensations from the skin maybe some the underlying tissue all right one other thing I want to mention here which is going to be important here is the wall we'll talk about a little bit more in dermatomes but it's called the Hilton's law it's not anything crazy all Helm's law says is any muscle that crosses a joint alright 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 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 I'll also supply the skin around that joint so again hilda's law states that 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 Oh / 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 gluteal nerve l5 s1 s2 forms the inferior gluteal 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 post your division which is only from l4 to s2 and tears tibial nerve look at all the massive buku amount of information that if this guy is going to be supplying and then the actual common fibular 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 as one as - s3 is the posterior cutaneous nerve and then off here we have a posterior division which is going to be s 1 and s 2 which is going to be the nerve to pair formas 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 operator in terms of which supplies the superior melas and the obturator internus and the last one is going to be s4 s5 and cox-2 go1 form the coccygeal plexus and then we again we talked about clinical correlations with sciatica may be 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 pain numbness tingling within a certain aspect of the leg which is gonna be the post here and lateral aspect of the actual entire leg iron injures 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 if you guys did please hit the like button comment down the comment section and please subscribe iron engineers as always until next time