Nerves of the lower limb

[Music] wait come on wake up it's it's Friday afternoon it's been a long week every week so long week and you can see what we've got going on on Monday we're running exams they'll be fine they've studied it hard there in the lab it's a nice exam it should be it's good they'll show off how much they know anywho so I'm in this room here are some students in the other room revising and this week gonna do a topic that to be honest I thought we'd already done well maybe I just blanked out and I've been trying to put it off because I didn't want to do it the topic this week is the nerves of the lower limb [Music] so the reason I've been putting off is I did it I couldn't look to Lowell in videos because I swore I'd done it I got so many lower-limb videos but we talked about the upper limb I think I did the nerves of the upper limb recently and that was a hard work no it it's not terribly complicated it's a little bit complicated it's terribly hard to put together now the nerves of the lower limb I think the reason the other reason I've been putting off is that often when I talk about the nurse the lower leg I'm talking to Annie statists and that's all thing we go into a little bit funky levels of detail which isn't really the aim of these videos the aim of these videos is to educate as many people as possible about the important things so I know that I know that these models [Music] needle in a brain gonna do it like this group if I only I'm going to make a mess gonna get all in everywhere right I know they're these models show a lot of the major nerves now we grew when we looked at the upper limb we talked about like the big four so in the lower limb we've also got you know a collection of big nerves we're gonna start on the top we're gonna follow them down but they're going to talk about the muscle groups and the compartments of the family and the leg that they innovate when we get the foot in line is there's a little bit more detail down there but money going to talk about the nerves I can see on here the cutaneous nerves have been taken away because we've to be okay we've taken away the cutaneous the skin bits right hey you know what what we're talking about the lower limb we can think about running and this might be a good time for me to remind you that I'm going to be running a hundred kilometers in one day for charity on the cot for a challenge in the middle of this year that's June 2018 and if you would like to be the wind at my back go the link below doneita just giving quid 50p 20p anything would be lovely well nothing don't I don't mind this point it's fine you know what help I can get a hundred K all right let's start at the front here so this this is the femoral nerve the femoral region of the lower limb is the thigh that's what ephemeral means of the thigh then you know that these arteries here they change their names on the artery here and then bein here they changed their name as they passed under the inguinal ligament we go from external iliac artery to femoral artery and that's not a thing we do with nerves nerves keep their name they changed their name when they split and divided into something else or if you get a new branch we give that a new name right so this is the the femoral nerve and it starts up it's it's from coming from the lumbar plate number plexus I don't really want to talk about the roots of nerves too much if you want to look at roots of nerves go look at a table in the textbook but they come from the lumbar plexus they're coming from the abdomen and then they passed down that this is psoas major here in iliacus and they put your passes down inferior or sit rather it passes deep to the inguinal ligament to get into the into the anterior compartment of the thigh and that's key so the femoral nerve passes into the anterior compartment of the thigh and it innovates the muscles of the thigh so the quadriceps femoris muscle group in innovate celiac is's is going past it innovates Sartorius I just took off here this is a really handy concept to consider right this is a left leg so I should stick with my left leg all right in the thigh we have three compartments we have an anterior compartment a medial compartment and a posterior compartment the muscles here are surrounded by fashion right we've got this this stocking of the fasciae latae and then we have the muscles and things supplying the muscles contained largely within a compartment things can pass between deposits but think of this anterior compartment mediocre pilot and posterior compartment now in the anterior compartment have quadriceps femoris and Sartorius and what-have-you and the the anterior compartment of the thigh is responsible for extension of the knee and flexion of the hip if you think about rectus femoris or more heavy right the medial compartment of the thigh is responsible for adduction bringing the leg back to the midline and then we have these muscles up here gluteus medius and minimus responsible for abduction and then of course the hamstrings and glutes use Maximus they do extension of the hip and of course flexion of the knee iso posterior compartment flexion of the knee extension of the hip got it so remember those compartments as we think about the nerves of the femoral nerve because if the anterior compartment of the thigh innovates that quadriceps muscle group and the reason I kept it keep taking Sartorius off is that while the moon while more while the femoral nerve is going into anterior compartment we can see this nerve running down here now deep to Sartorius we have this thing that we call the sub sartorial canal alright there's there are this groove underneath Sartorius and through here we see this neurovascular bundle running down there now you know that the femoral artery here it's gonna run medially this is the medial knee here it's gonna run immediately because it's going to run through that gap in adductor Magnus the adductor hiatus so that you can get to you love to squeaking on oud so it can get to the popliteal fossa here and then becomes the popliteal artery right this move running with it is actually the saphenous nerve and it's like it's a cutaneous branch is the sensory a skinny a skin sensory branch of the femoral nerve and what it's doing is it's getting out to the medial knee the medial leg and the medial ankle is going to carry sensory innervation back from the skin over there so that's what that is the femoral nerve itself disappears in here we don't we take this off we don't really see it we just see loads of muscle all right so that's the family here see this nerve here again running with the blood vessel that's the obturator nerve now the obturator nerve we can find in the pelvis this pelvis my looking little bit more tilted than maybe you're used to if you used to look in yeah our pelvis in the lab kind of because it kind of sits on the table like that right was actually in us it's tilted like this so so here's the pubis here's the here's the fake rum right I mean what we have here is this is like the the brim of the bowl of the pelvis so here's the pelvis right so because the left side I see the you know the brim round here so the operator if you find a nerve running around the brim of the pelvis it's gonna be the obturator live reason is is because that that's the obturator foramen and if you look at a completely naked skeleton there's a big hole there I picked this model because it shows ligaments and connective tissue and there's a membrane covering most of the obturator foramen why well because there are a whole bunch of muscles here or there now I know we've done yeah we've done me like the internal and external rotators of the hip and me the deep muscles here so the short rotator muscles of the hip that they attach to this surface which gives them a bit more stuff to attach to but there's a little teeny-weeny hole in the superior part of it there right and that's where the operator nerve runs and that means that it can get to the medial compartment of the thigh and it's responsible them for innovating the adductor muscles it innovates all of the adductor muscles in here except for a little bit of a dr. Magnus which is a little bit what we might call hamstring II is a little bit on the posterior side and that gets innovation from the next nerve we're going to talk about so you see we're going to talk about the focusing on the compartments right so we've got anterior compartment we've seen innovated by the femoral nerve medial compartment is innovated by the obturator nerve had just leaves us with the posterior compartment kind of so in here we find the hamstrings and you know the nerve that runs through here I'm sure you do if we take off gluteus maximus we see it on these models it's a little weary thing whenever we dissect we find a huge great big sciatic nerve here's the piriformis muscle the pear-shaped muscle and the period for every year and the sciatic nerve usually pops out from underneath inferior to the piriformis muscle sometimes it splits and to part one bar goes through piriformis and or over the top and underneath one but most of the time this is what we see we see piriformis we see huge really exciting nerve popping out from underneath it now the sciatic nerve if I take the hamstrings off runs down the posterior compartment of the thigh and at some point it's split into two nerves it splits into the common fibular nerve or common peroneal nerve and into the tibial nerve and last week we were talking about the the posterior compartment of the leg and in there we had the tibial nerve now where this splits is variable when we when we dissect the lower limb we find this sometimes it splits Lotte sometimes it's placed higher up usually it splits higher up than we see in most of the models is up here somewhere but also like the connective tissue is kind of holding the two divisions together so in fact you could you not entire partnership it's higher anyway what that means is that you might read about all of the muscles of the posterior compartment of the thigh are innervated by the tibial division of the sciatic nerve just because it's you know it's very sciatic up here and it's split down here and it's sending off branches to these muscles as it goes down right the biceps femoris muscle it's called biceps because it has two heads by two steps couple of two heads so the short head of bicep stack which is right down here right the short head of biceps femoris gets some innovation from the common fibular nut but see this was supposed to be easy and I'm getting into too much detail also you've got to watch out because sometimes my tongue runs away from my brain and whilst most of this information is fairly safe in my brain getting it out doesn't always go to plant the sciatic nerve and these two divisions innervate the muscles of the posterior compartment of the thigh good but also up here we've got these guys the gluteal muscles are not innovated by the sciatic nerve they're innovated by branches of the sacral plexus so the central plexus is what we see in here inside the pelvis and we've got gluteus maximus here and then here we've got a pair of muscles gluteus medius and minimus kind of over the top of each other and they have their own gluteal nerve so we have a superior and inferior gluteal nerves can you see that gluteus medius and minimus are more superior than gluteus maximus so gluteus maximus is innervated by the inferior gluteal nerve and gluteus medius and minimus are innervated by the superior gluteal nerve both those nerves also pop out from around piriformis out period and they just they just get that right it's pretty cool these nerves are really important these nerves get damaged then you can't do abduction now the reason abduction is important of the of the hip is that when you walk you might not often walk backwards but there you go when you walk with every step you take one foot off the ground so what this means is there while the muscles here when they contracted gluteus medius and minimus will abduct the the femur at the hip what they'll also do is they have to contract when you take one foot off the floor to keep the pelvis level if the muscles relaxed then my hip drops so to keep can you see so to keep my so to keep my pelvis level when I take one for four grand these contract which means that if the nerve to this these muscles gluteus medius and minimus is injured or if the nerves themselves or the nostrils themselves a week then the hip on the other side is going to drop so what this means is that instead of bringing your foot through normally the the foot tends to tends to dry can you have this Dragon Gate so I fast the nerves of the thigh we now need to go beyond the knee into the leg and then the ankle and the foot so then we've got the tibial nerve which is going to continue into the the posterior leg it's going to innovate all of the muscles of the of the posterior leg and the tibial nerve then continues down and then it's going to pass look there's the big toe so this is medial so it's going to pass deep to the retinaculum around here and it splits that's where the tibial nerve ends and it splits into medial and lateral plantar nerve so it's going underneath the which mmm those nerves are pleasant present on this model there we go so there's the tibial nerve coming around here and then it's split so there's the big toe so this is medial so this is the medial plantar nerve that's laterals there's a lateral plantar nerve so he's innovating all this stuff stuff on the plantar surface of the foot so we've got lots of little muscles down here lots of intrinsic muscles of the foot and you've also got this skin right so that's all tibial nerve now we go back up to the canoe so here's the common fibular division of the sciatic nerve and look this is going out laterally here and it's going over this bulge and you can palpate this bowl so you can so you can find your own common fibular nerve right I'll get my leg up here actually pull me alright so back there that's the head of my fibula bone right so the common fibular nerve or common peroneal nerve if you prefer the reason I don't like peroneal nerve P er o-n-e al nerve is because if you spell it wrong right peroneal nerve that's completely different isn't it I think fibula nerves easier and of course we talked about the fibula bump anyway so common fibular nerve runs over the head of the fibula and goes out there so you can palpate that yourself Oh get in the wrong place you've all so if I use this guy that tibia fibula head of the fibula common fibular nerve runs over this yeah [Applause] and the reason of course is called the common fibular nerve is because you kind of split into uncommon bits it's going to divide into deep and superficial fibula nerves now the superficial fibular nerve will stay lateral so it's going to go into the lateral compartment of the car so we have this posterior compartment we have a lateral compartment with fibularis brevis and fibularis longus muscles in it and we have an anterior which is very funny to be honest anterior and all that stuff so just like a five-year three components so the superficial fibular nerve runs into the lateral compartment of the leg and innovates fibularis brevis and fibularis longus the deep fibular nerve runs deep and that gets to the anterior compartment of the leg and innovates these muscles around here now we can also see these nerves here confusingly these nerves they're probably fashion if I tell you this often you see all right right so this this muscle here is extensor digitorum longus not the tendons are going to the digits to the toes and it's going to extend them and if we take that muscle off there there we can see inside the anterior compartment of the leg and that's the deep fibular nerve there see how it stays deep which means that if I put this muscle back on again these two nerves that we can see here are in fact branches of the superficial fibular nerve this is how the superficial fibular nerve ends it gives off a couple of branches here you see how they've run into the dorsum of the foot this is the dorsal surface right the top of the foot and one nerve is running medially and one nerve is running laterally then this is the the medial dorsal cutaneous nerve of the foot medial dorsal dawson cutaneous skin and this is the lateral dorsal cutaneous nerve the foot and you can see that this one's gonna run down to the digits and essentially they're carrying sensory innervation from the dorsum the digits now the thing that's a bit funky here and rather cool maybe not the thing that's a little bit weird is that this deep fibular nerve actually stays deep to all of this stuff and that's what we can see popping out here so you see between the great toe and the second - no there's another nerve there but it's not it's not a branch from these guys that's actually popping out from underneath these muscles so this is a this is like the the last part that the terminal bit of the deep fibular nerve and this is just carrying sensory innervation from the skin between these two toes does that make sense can you imagine that so the skin up here is carrying the sensory innervation on the skin up here is carried by the the superficial fibular nerve and then the innovation from the skin in between these two toes is carried by the the the deep fibular nerve weird I know but there is but that's it all right so we talked about the shoe removed last week in the posterior leg but other than talking about all the cutaneous nose which I don't think we'd want to do at this stage that's it so when you're thinking about the the nerves of the lower limb think about the compartments the leavener squeak posterior compartment of the leg lateral compartment of the leg anterior compartment of the leg the nerves that run through each tibial nerve superficial fibula deep fibula and likewise in the thigh think of the posterior compartment medial compartment and anterior compartment waspy hamstrings of the thigh you will remember that the sciatic nerve runs posteriorly in the posterior compartment and splits into tibial and common fibular divisions remember the gluteal muscles have got their own nerves and the femoral nerve innervates anterior compartment obturator nerve innervates the medial compartment see that's what I thought I talked about it before it's because I'm always talking about these nerves always talking about the nerves of the lower limb that hopefully is straight forward it's gone dark hair so can you hear the pitter-patter of the I'm gonna get wet so I can home bay that's living in South Wales you get wet but we've got the seas okay um right see you guys next week [Music]

Channel: Sam Webster

Views: 184,157

Rating: 4.8970737 out of 5

Keywords: leg, thigh, lower limb, anatomy, human anatomy, femoral nerve, obturator nerve, sciatic nerve, tibial nerve, common fibular nerve, superficial fibular nerve, deep fibular nerve, peroneal nerve, dorsal cutaneous nerve, plantar nerve, saphenous nerve, Sam Webster, Swansea, dontbeasalmon

Id: LgOapFpY9xM

Length: 21min 15sec (1275 seconds)

Published: Mon Mar 12 2018