iein in generics in this video we are gonna talk about the brachial plexus super important plexus so let's go ahead and get started first things first we should know the brachial plexus right from what part of the actual spinal cord does it start and at what point does it end so we say that it generally starts around c5 it might gain some branches from c4 but for the most point most part it starts here at c5 and then it goes down c6 c7 c8 and then we can go to t1 and again we've already explained why this is c8 right we've said that it's actually running in between the first thoracic vertebrae and the seventh cervical vertebrae there's not going to be eight cervical vertebrae but there is going to be eight pairs of cervical spinal nerves alright anyway first thing I want you guys to remember about the brachial plexus on guys well I want you guys to remember something please remember it remember to drink cold beer alright so first thing I want you to remember is to remember to drink cold beer alright that's the first thing I want you guys to remember next thing I want you guys to remember is what's called Mar mu so remember Mar mu M ay R M U now you probably like what in the world does this stand for so the R is gonna stand for root so it's gonna be root T is for the trunk D is for the division C is for the chords and then the B is going to be for the branches okay now as we come down down this vertical part here the Mar mu M is for musculocutaneous okay so there's going to be two ends but the first one is going to be musculocutaneous nerve all right the second one a is for axillary nerve so we're just kind of laying the groundwork for our brachial plexus so then we can have our diagram in there so we can get this stuff memorized very very well so the axillary nerve next one our radial nerve okay then after that we're gonna have the median nerve and we'll finish off here with the ulnar nerve okay now in this video what we're gonna do is is we're gonna talk about the structure of the brachial plexus the branches of the brachial plexus and some minor ones and then we're gonna talk about the muscles and cutaneous supply all right so let's go ahead and get started here first off the root first thing I want you guys to remember here is that the c5 nerve root and the c6 nerve roots actually come together so if we have here the c6 nerve root and the c5 nerve root these guys will actually come together when they come together they're gonna form a nice little trunk right there alright so now the next thing is the c7 root actually feeds into his own trunk okay so we're gonna c5 c6 roots coming together and forming this trunk they see seven root will feed into its own trunk and the c8 and the t1 root will come together and form their trunk so now let's go ahead and organize this now so we have c5 c6 roots coming together in forming this trunk now the question is what is this trunk what is this trunk what is this trunk let's go from top to bottom or upper to lower hey so this should be the upper trunk very very simple here so this part right here is going to be the upper trunk this one right here will be the middle trunk and this bottom one down here is going to be the lower trunk very very self-explanatory for the most part right now the next thing that's going to happen here is we're gonna take this upper trunk middle trunk and lower trunk and all of them are gonna break off into divisions so let's see that now so now we're gonna have here's we're gonna have the upper trunk he's going to branch into an anterior division and a posterior division so look here we're gonna have a posterior division right here and then over here same thing this guy is going to branch out this guy's going to branch out let's have this one as an anterior division and then up here we're gonna have an anterior division now the reason why these divisions are important is because some of these actual divisions are going to combine together and form special chords and that's why we're mentioning so again the upper trunk splits into an anterior division a posterior division the middle trunk spits the splits into a anterior division and guess what Oh a posterior division and the last one same thing here I'm gonna switch it up though and I want to have the posterior division here going up you'll see why it's going to be easier for diagrammatic purposes we're gonna have to post your division and same thing here what else should we have left over we should have the anterior division okay sweet deal so now we have all our divisions here's what I want you guys to remember once we have the anterior and posterior divisions I want you to take all the posterior divisions and combine them together alright so that's what we're going to do now what I'm gonna do here is I'm going to bring this posterior division up this posterior division up and then these guys are gonna combine so now let's bring this guy up a little bit like this bring this one like this and we're going to have this posterior division like this all of these guys combine when they combine they form a cord okay and that cord is actually going to be a special one that will branch off into these different nerves so now the question is what is this cord here that we're gonna form so let's actually bring these together a little bit closer so we can have this cord here this cord is going to be called the posterior cord okay the posterior cord and it's going to be formed by the posterior division of the upper trunk middle trunk and lower trunk so let's draw like this let's have this one like this and we're gonna have all of these guys combining together here and then they're gonna split okay and again flow down like this and then split into this and this okay so now what is this cord right here this cord is called the posterior cord okay it's called the posterior cord in the posterior cord is going to be formed by the poster vision of the upper trunk middle trunk lower trunk then it's gonna branch out into the axillary and radial nerve next thing the anterior division of the upper trunk and the middle trunk are gonna come together okay now these guys will come together let's do these in a different color so we don't confuse them with these let's do it in red so now the anterior division is gonna come up here and it's gonna combine with the anterior division here and what these are gonna do is they're gonna form a nice cord that'll go to the musculocutaneous it'll form the branch of the muscular cutaneous whereas the posterior cord Gav branches to the axillary and the radial what is this court called this cord is actually going to be specifically the lateral cord okay this is called the lateral cord okay now the last and final one here is we're gonna have the anterior division and the anterior division here is actually going to go and supply the ulnar nerve so let's bring the ulnar nerve down here a little bit bring the median down a little bit let's bring the old are down a little bit so here's gonna be the median nerve and then down here a little bit below is gonna be the ulnar nerve alright sweet now same thing let's switch the color up a little bit let's do purples let's take the anterior division here and this anterior division is going to basically come and supply the ulnar nerve so he makes his own chord what is this chord so now here's a bad best way to remember onar remember it's on there gonna be the own R bone right so the own are bone which is on the pinky side so that's medial if you're an anatomical position so this should be the medial cord all right now last one here is we have the median nerve here the median nerve is going to be formed by branches of the medial cord and the lateral cord so now look what happens here the lateral cord is gonna come down here like this alright and the medial cord is gonna come over here like this and these both will come and supply the median nerve here so the median nerve is going to be formed by branches of the lateral cord and by branches of the medial cord that is gonna give us bayed the basic structure of our brachial plexus here now next thing I want to do before before I start going over all the muscular supply of those nerves is I want to cover some small branches first so if we come back over here we had the root back here right let's bring our root over here a little bit more this is our root and again to bring the trunk over a little bit more over here but the trunk right here so off of the c5 route there's a branch a special little branch coming off of this c5 route and this guy is gonna go to some special muscles here okay what is this nerve here called this is called the dorsal scapular nerve okay the dorsal scapular nerve he's gonna supply two muscles well actually three if we combined the rhomboids into two different parts you know the rhomboids you have the major and then you have the minor if you guys remember from our muscle anatomy videos we say that these two are responsible for retraction of the scapula the other muscle that it's going to supply is going to be what's called the Levitt or scapula and the Levitt or scapula was important for being able to elevate the scapula now the next one that we should know is a very important one he's going to be running on the sides there it makes like those little cutting muscles that you can kind of see serrated edges and that's called the serratus anterior the serratus anterior is actually going to be formed by three nerve roots so you know c5 c5 can actually run down here he can pick up a branch from c6 and then c6 and c5 will run down here continuously and they're like hey let me pick up another branch and they pick up one more branch and that is going to be from c7 this nerve is called the long thoracic nerve the long thoracic nerve is super important it goes and supplies a special muscle that helps us to protract that scapula and that muscle is called the serratus anterior okay so that's gonna be for from the c5 c6 and c7 nerve root next is the upper trunk there's two branches that come off of that one one of them is gonna be called the Supra scapular nerve the suprascapular so this one is gonna be called the Supra not sub-par the Supra scapular nerve and this guy is gonna go to two muscles it actually supplies around the shoulder joint but he supplies two muscles around that shoulder joint and that is going to be called the supraspinatus which performs weep the weak abduction so supraspinatus and another one which is gonna be below the spine of the actual spine of the scapula and that's gonna be called the infra spine anus and he helps to perform like lateral rotation at the shoulder joint but again he can also supply the shoulder joint okay so that's a super scapular now this is another little minor one not super super crazy but there is a nerve that actually comes off here in supplies the subclavius muscle which is underneath the clavicle so they call this the nerve to subclavius and the nerve to subclavius will guess what do you what do you think it's going to go to it's gonna go to the subclavius muscle and the subclavius is important for being able to depress the clavicle so he depresses the clavicle all right sweet friggin deal now let's keep going as we go down here we're gonna come to the cords now the lateral cord is going to have a special muscle a special nerve coming off of it let's actually keep it in red here there's a branch coming off of the lateral chord let's do that one right here and this guy is called the lateral pectoral nerve so this one is gonna be called the lateral pectoral nerve now the lateral pectoral nerve he is gonna go and supply a special muscle okay that muscle he is gonna supply is going to be called the pectoralis major the pectoralis major okay so we got the lateral pectoral nerve which is going to come off the lateral cord and supply the pectoralis major now we have the posterior cord the posterior cord has a couple branches that come off there too so what does the posterior cord give off all right let's keep these in black the posterior cord has three branches boom-boom let's do one more let's come down here again boom okay three branches here this one right here is called the upper sub this won't soup brought back there this is sub scapular nerve this one here they actually have two names for it the middle subscapular nerve or the better name the Thor a course alert so this one right here is gonna be called the thorax dorsal nerve and then you have one more and what do you think this one is guys this one right here is specifically the lower subscapular nerve okay so we have one more and that is going to be called the lower subscapular nerve okay lower sub scapular nerve okay the upper subscapular nerve is gonna be supplying what muscle the subscapularis so you pre easy right so this guy is gonna supply the sub scapularis what does the subscapularis do well based upon his origin and insertion he helps to be able to cause medial rotation of the scapula okay or internal rotation of the scapula the next one which is the thorah code dorsal nerve he is gonna go to what's called the latissimus dorsi the latissimus dorsi has so many different functions you know it helps to be able to extend at the shoulder joint immediately rotates at the shoulder joint and abducts at the shoulder joint so many functions for this guy now the lower subscapular nerve is actually going to give off two branches all right what's gonna supply two muscles okay it's gonna supply the subscapularis but it's also going to supply another muscle which performs the exact same functions of this latissimus dorsi and that is going to be the teres major okay so the teres major is going to perform the exact same functions of let's dismiss Taurus and what was that extension adduction and medial rotation at the shoulder joint subscapularis again medial rotation at the shoulder joint all right as we are so close we got this medial cord now the medial cord it has three branches okay so if you remember up there at the lateral cord that had the lateral pectoral nerve the medial cord should have the medial pectoral nerve so this one should be the medial pack torille nerve and then this one right here this is going to be the medial brachial cutaneous and then the last one is going to be the medial not that medial antebrachial cutaneous how many branches off of this son-of-a-gun alright so now we've covered that right medial pectoral nerve what is it supply the medial pectoral nerve is actually gonna supply the pectoralis major and minor so he's gonna supply thee packed her Allis major and pectoralis minor now that begs the question what is the difference in these two muscles the pectoralis major he performs flexion at the shoulder joint he performs medial rotation at the shoulder dress so he again he performs flexion of the shoulder joint medial rotation at the shoulder joint and adduction at the shoulder joint the pectoralis minor is specific for protraction of that scapula okay so these are going to be supplied by that nerve the medial break you cutaneous it's better if I show you on myself here so if I take here I'm fat so don't don't make fun of you guys but if you look here we have the medial breakage cutaneous it's gonna supply more of the posterior and medial surface of the brachial region okay so that's like right here if we go a little bit more anteriorly right then you're gonna have the medial antebrachial contains key supplies here and continues down the forearm okay so again medial break you cutaneous is going to be more post tearily immediately and then the medial antebrachial cane is gonna be a little bit more anteriorly on this brachial region and down to the forearm okay it's better if I show you on that even though I'm fat okay so now we've covered those minor branches now let's get to the meat and potatoes these big boys here okay Musca cutaneous nerve what does this sucker do he has two branches okay so it's always good to know for these big ones they have Accutane branch and they have a motor branch so let's go ahead and say we talk about first the cutaneous branch cutaneous branch is pretty easy okay the cutaneous branch for this mofo is going to be the lateral forearm so this applies primarily the lateral forearm and again it's picking up like taht it's gonna pick up some of the touch that pain the temperature from the lateral forearm okay that's the cutaneous branch what about the motor branch the motor branch again not a lot for this guy thankfully the motor branch is going to go to three muscles one is the coracobrachialis okay so the core Co brachialis another one is the brachialis the breaky Allis and the last one is the biceps brachii which is both the short and long head okay now what did these muscles do the coracobrachialis he has two functions one is he flexes at the shoulder joint the other one is he add Ducks at the shoulder joint okay don't laugh when I push I got man boobs okay so brachialis what does he do he flexes at the elbow joint the biceps brachii he also flexes at the elbow joint but he can also supinate the palm okay so that's that so let's come back to the axillary nerve the axillary nerve you know actually runs through a space where around the shoulder drink called the quadrangular space and what it does is it supplies has two components a cutaneous branch again cutaneous branch and a motor branch the cutaneous branch is pretty simple it supplies a patch of skin on the posterior and lateral surface of the deltoid so posterior and lateral surface of the deltoid so posterior and lateral surface of deltoid all right that's that guy what about the motor branch the motor branch is gonna supply two muscles okay what are those two muscles it is gonna supply the deltoid muscle okay so the motor branch will give fibers to the deltoid and another one which is going to be called the teres minor so the deltoid muscle what can it do well it has a bunch of different functions and I technically three functions because you have your anterior your lateral and your posterior fibers the anterior fibers can help with flexion at the shoulder joint the lateral fibers can help with aDNA ab abduction at the shoulder joint and the posterior fibers can help with extension of the shoulder joint the teres minor plays a role within lateral rotation or external rotation of the shoulder joint okay so that is that guy right there now we come to the Big Mama the radial nerve the radial nerve has so many different muscles that it can supply alright so first let's do the cutaneous okay the cutaneous branch is this applies a good portion of our our arm a very very large portion so they say that it generally supplies the posterior right the posterior and lateral surface of upper limb and it also supplies another area it supplies the dorsum of the hand but remember we always have to assume when we're doing this when I'm telling you guys this we're in anatomical position so this is anatomical position here with my palms facing forward so when I say dorsum we're talking about this part here and this is the radial side so it should be dorsal and lateral surface of the hand so it's gonna supply the posterior and lateral surface of the upper limb and the dorsal and lateral surface of the hand and it also can supply the pole Lex okay so it also supplies the pole Lex and the pole Lex whole Lex is just basically another word for your thumb okay now that's the cutaneous branch what about that motor branch now this guy he likes to make a statement okay so now what I'm gonna do here is I'm gonna move the subscapularis out of the way but just down here okay so lower subscapular nerve just remember it's subscapularis and the Terry's major okay now this guy here the motor branch get ready this guy supply so many okay so the radial nerve start from the top work your way down so the first one is going to supply the muscles of the posterior arm your extensor muscles specifically the triceps brachii so we're gonna start at the top and work way down so triceps break I all the different heads and these muscles you know the triceps brachii plays a role with an extension at the elbow joint it also supplies another extender at the elbow joint which is the anconeus then if we come down we're gonna come to the forearm muscles easiest way to remember is it supplies almost all of the extensor compartment of the forearm so work our way that way so now next muscle is the brachioradialis so he supplies the brachial radialis then if you go out from that point we're gonna hit the extend sore carpi radialis longus and right next to it should be brevis so it's going to supply those two muscles and remember brachioradialis is flexion at the forearm by reflection at the elbow joint and the extensor carpi radialis longus and brevis extend the wrist then if you go next to that you have the extend sore digitorum then there's another one the extensors in dices which extends the index finger the pointer finger right then there's another one extensive little digit little pinky that is the extend sore digiti minimi what else ah hi so we're God these guys let's go ahead a little bit more ours there's another muscle here which is called the extensor carpi ulnaris so it supplies another muscle so what we're going to do is we're going to work over here someone box off the cutaneous branches okay and we're gonna continue over here with the motor branches so we're going to continue from this point and we're gonna stay extensor carpi ulnaris so extend sore carpi ulnaris then work your way down here to like the anatomical snuffbox region I like that name it's an Tomiko stuff box region you have the abductor pollicis longus you have the extensor pollicis brevis and the extensor pollicis longus in that area it supplies those guys so supplies the abductor pollicis longus and it supplies another one which is the extensor pollicis longus and brevis the extensor pollicis longus and brevis now there's another one that I can't forget you know um underneath the brachioradialis is a really deep muscle that helps to supinate the palm really really important muscle he's called the supinator so it also is going to give a branch here to a deep muscle called the supinator okay so we've covered the radial nerve branches for the motor branch and the cutaneous branch so again remember this is the motor branches that we covered and these are the cutaneous branches that we now we go into the next one the media nerf it's also a little bit challenging too so we'll hit that one let's do this one and baby blue okay again we're gonna have a cutaneous branch and what is the cutaneous branch the cutaneous branch for the median nerve is it's actually going to supply the ventral so if we look here anatomical position the ventral and lateral surface of the palm okay and the digits the ventral surface of digits two and three also so it's gonna supply the ventral and lateral surface of the palm the anterior surface of digits two and three and the dorsum of fingers two and three remember that so cutaneous British ventral and lateral and we can say technically two-thirds of hand and digits two and three on the ventral and dorsal surface all right that's the cutaneous branch now we got to do the motor branch the motor branch it has a decent amount also so the motor branch what are some of those okay so with this guy the median nerve he's kind of a culprit for a lot of people who are very active and typing and all that kind of stuff you know it actually runs in the carpal tunnel underneath the transverse carpal ligament and as that nerve gets compressed it can cause carpal tunnel syndrome the motor branch hair supplies a lot of muscle hair so let's go ahead and think about the flexor compartment so the flexor compartment what do we have we have the pronator terry's and then we have the quadratus so we have the pronator terry's and quadratus if we go a little bit outwards from that well then we have the palmaris longus and the flexor carpi radialis so flexor carpi radialis and then out from that one is going to be the palmaris longus okay now if you think about another one you can continue to go deep right this is the underneath underneath those muscles there's another muscle it's actually called the flexor digitorum superficialis and then there's another one right there's you know there's a muscle really deep under here it's actually called the flexor digitorum profundus it's actually gonna supply the radial half of flexor digitorum profundus alright so we got that now it'll continue down as it continues down it actually is going to supply some of the you know they had the lumbricals right here the second and third lumbricals so it'll also supply the second and third lumbrical muscles and it'll also give supply to these thinner muscles three of them what are they okay so you have specifically the opponens pollicis brevis then another one which is called the flexor pollicis brevis and the last one which is called the ab doctor abductor pollicis brevis whew a lot of muscles for this guy okay so we got the cutaneous branch and we got the motor branch pronator muscles they pronate the palm flexor carpi radialis flexes the wrist palmaris longus flexes the wrist flexor digitorum superficialis flexes the digits and then eventually the wrist flexor digitorum profundus flexes the digits so most of these are gonna tell you what they need the lumbricals are intrinsic hand muscles the opponens pollicis brevis helps with what's called a position being able to touch your thumb to all the other different fingers the flexor pollicis brevis flexes the the actual thumb and the abductor pollicis brevis abducts with them so a lot of these muscles their action is said within their name come to the last one the ulnar nerve the ulnar nerve this guy again has a cutaneous branch and he has a motor branch thankfully this one doesn't have a lot of muscles the cutaneous branch is actually pretty easy so think about like this okay by taking my hand again anatomical position this is the ulnar side right pinky side if you think about it this whole side was supplied already so the ventral two-thirds right and the dorsal two-thirds of the hand so what's left the ventral and medial one-third of the hand and the dorsal medial one-third to him that's it so it supplies I got them in my pocket I got the ventral and dorsal so ventral and dorsal one third of the hand simple as that super easy okay now we come to the motor branch so remember the median nerve supplied a lot of the thenar muscles well the older nerve gives off a branch that kind of flies over there and supplies another one so another branch here off of this guy it comes over here and supplies the adductor pollicis brevis okay well let's think about the other muscle over here what was another muscle that could be right over here the flexor carpi ulnaris right another one is remember we had that half of that digitorum profundus the flexor digitorum profundus well the owner half so we have two muscles now the ulnar half of flexor digitorum profundus and the flexor carpi ulnaris last couple muscles the hypothenar muscles so on this side okay there's three of them there the opponens digiti minimi the flexor digiti minimi and one more and that is the abductor digiti minimi one more and that is the ab dr. digiti minimi iana so I pretty much covers the brachial plexus I hope it made sense I really do hope you guys enjoyed hope you guys learn something from it if you guys did please hit that like button comment on the comment section and please subscribe also if you guys get a chance go check out our Instagram our Facebook and even our patreon all right engineers as always until next time [Music] you [Music]