0:12 [Music]
0:14 hello again you guys are feeling a bit
0:16 busy today today we're going to look at
0:19 the nerves of the upper limb I'm not
0:21 gonna cover the brachial plexus I am
0:23 gonna cover the big four nerves has been
0:25 run down from the shoulder distally
0:28 towards the hand the aim is to have like
0:32 a visual idea of where those nerves run
0:34 by the big4 I mean musculocutaneous
0:37 median ulnar and radial whenever you
0:39 have a list of things like why is the
0:40 last one always hard to understand cough
0:43 anyway before and then I'm gonna add in
0:46 a few extras and just for fun we're
0:48 gonna talk about the cutaneous nerves -
0:50 the skin of the upper limb as well all
0:58 right I'm really going to say about the
1:02 brachial plexus is that it arises in the
1:04 neck so one week we'll have a look at
1:05 the nerves in the neck we'll have a look
1:07 at the nerves around the shoulder shall we
1:07 we
1:09 but the brachial plexus pops out between
1:11 the anterior and the middle scalene
1:14 muscles of the neck those muscles are
1:15 running between the cervical vertebrae
1:18 and the ribs so that the roots of the
1:20 brachial plexus pop out from there and
1:23 then they they get into the Zillah and
1:26 when they're in the axilla we see the
1:29 cords forming around the exilair artery
1:32 and then we go into the upper limb the
1:33 main purpose of the brachial plexus then
1:37 is to carry nerves from well spinal
1:40 nerves from the spinal cord acting to
1:42 the upper limb and the brachial plexus
1:45 is making those four main nerves but
1:46 it's also making a few other little
1:48 nerves so there are lots of nerves
1:49 around the shoulder region here which
1:51 I'm not going to talk about but we'll
1:52 start in here so that's what we're
1:54 seeing on this model here this model
1:57 here is the right arm it's upside down
2:00 right so
2:06 deltoid um mm-hmm
2:09 so what's in this princess is bigger
2:11 than mine oh it's bad thing it's what's
2:14 losin tit so that's what we're seeing up
2:16 here we're seeing the past the brachial
2:19 plexus and this is the angular II artery
2:21 this artery is a good landmark because
2:24 we're following these nerves into the
2:26 upper limb it starts off as the
2:28 subclavian artery when it runs by the
2:30 clavicle is it passes the first rib then
2:32 it becomes the axillary artery it goes
2:34 into the exhilarate passes
2:38 I think distal to teres major so around
2:40 there we then call it the brachial
2:41 artery so there's a bit of terminology
2:45 as well this part of the arm up here the
2:47 upper arm you might say we call the
2:50 brachial so you might find nerves which
2:51 have you know the term brachial in them
2:54 better that they're in this region and
2:56 then the rest of the arm to the wrist
2:57 this is the what we might call the
2:59 forearm also gets called the
3:02 antebrachium so like cutaneous nerves in
3:04 this region get called the you know anti
3:07 anti anti brachial nerves
3:13 so like the medial antebrachial the the
3:16 medial cutaneous antebrachial nerve
3:18 something like that which miles called
3:19 the medial continuous nerves of the
3:22 forearm I'm gonna use for arm without
3:24 arm today we came across antebrachium
3:24 and break him
3:26 that's all they all they mean right
3:29 breaking antebrachium anywho so here's
3:31 that auxilary artery and you can see it
3:34 there it's surrounded by these nerves
3:35 that are forming from the brachial
3:41 plexus now if we look so is biceps
3:43 there's the anterior surface of the
3:46 scapula there's a clavicle there and if
3:47 we turn this around so here who are the
3:52 tendons of biceps you can see in here
3:55 we've got a couple of nerves coming off
3:58 the brachial plexus and going kind of
4:00 post earring Lior laterally so we've got
4:02 the humerus running in here haven't we
4:04 now those two nerves they would you see
4:06 to live there because there are all
4:08 there's another one there are three
4:11 nerves in here which are like running
4:14 kind of kind of disappearing
4:16 and we've got the axillary nerve and the
4:18 radial nerve and we've also got the
4:21 musculocutaneous nerve now if we take
4:25 the anxiety nerve that's the first one
4:29 on the exhuming nerve then ah there we go
4:29 go
4:33 I'll see it here so the axillary nerve
4:39 is this branch here it's this branch
4:43 here and it's nipping in there and it's
4:45 passing passing here through this gap
4:47 and what its gonna do is it's gonna it's
4:50 gonna kill arraign the surgical neck of
4:57 the humerus by which I mean is the
4:59 humerus it's gonna it's gonna curl
5:00 around on the surgical neck of the
5:02 humerus here and it's gonna pop out
5:06 their posterior Li and that's the turn
5:07 this around so there's the head of the
5:09 humerus there's the surgical neck of the
5:11 humerus there it is there as popping out
5:14 popping out here right so what the
5:15 axillary artery is good sorry what the
5:20 exilic nerve is going to innovate is the
5:23 deltoid muscle right so this muscle here
5:25 it's also going to innovate some of the
5:26 skin around them I'll come back through
5:29 cutaneous innovation at the end so then
5:30 the auxilary nerve the reason is
5:33 wrapping around like this is to get to
5:35 innovate the the deltoid muscle out here
5:41 and also to get to teres minor so on the
5:43 scapula we've got this is the spine of
5:45 the scapula super space is up here
5:47 infraspinatus and teres minor there and
5:50 terah's major here now if you look the
5:51 nerve equality laughing Villere nerve
5:54 now the other nerve I like also I'm not
5:55 be able to see on this one okay
5:58 I've these three branches here second
5:59 one is the musculocutaneous nerve and
6:02 the third one because we can see this is
6:03 going into choice if the third one is
6:05 the radial nerve the radial nerve is
6:06 essentially doing the same thing it's
6:09 gonna run post II really around the
6:11 humerus to get to the posterior
6:14 compartment its main job here is to
6:18 innervate triceps so the extensors of
6:20 the elbow this posterior compartment of
6:23 the arm it's also gonna carry cutaneous
6:25 innervation from the
6:28 and there it is there now this wraps
6:30 around the humerus
6:32 more inferior ly but there's the radial
6:39 nerve the radial nerve it comes around
6:41 in this direction but it winds its way
6:47 around the humerus kind of Ryan the mid
6:50 shaft so this means that a fracture of
6:52 the humerus could damage one of these
6:54 nerves if the fracture is up at the
6:56 surgical neck there's a risk of damaging
6:58 the angular II nerve and if the fracture
7:01 is kind of in the mid humerus mid shaft
7:05 then there's a twisted in it then
7:08 there's a risk of damage the radial
7:10 nerve I can see a bit of a spiral a
7:12 spiral shape to that to the bone here
7:14 there is a video on the humerus where we
7:16 talked about the detail the detailed
7:17 bits of the humerus and there is a
7:21 groove a spiraling also if orthopedic
7:24 surgery is maybe repairing a bone after
7:26 a fracture the surgeon also has to watch
7:28 out the radial nerve they weren't
7:31 screwing things back again now the elbow
7:33 so this is the cubital fossa right in
7:36 the anterior part of the elbow if I take
7:39 off so we've got brachioradialis here
7:40 and what-have-you if I take that off
7:43 then we can see the radial nerve so this
7:46 means that the radial nerve this is the
7:48 lateral epicondyle of the humerus
7:52 so this lateral epicondyle here right so
7:57 on you at your elbow you've got your
8:00 medial epicondyle here this bony bit in
8:02 your lateral epicondyle there that bony
8:04 bit this means that the radius then is
8:06 actually coming around anteriorly so
8:08 although it's innovating the posterior
8:10 compartment of the arm the radial nerve
8:12 comes around anteriorly at the elbow
8:15 anterior to that that epicondyle and
8:17 that's what we see here and then it
8:19 splits into superficial and deep
8:22 branches now we can see the superficial
8:25 branch here now that we've taken this
8:29 month this muscle layer off now the
8:31 superficial branch is just gonna carry
8:34 cutaneous innervation as it descends
8:35 down here we can see it popping up again
8:37 if I put this back on
8:44 you get an idea of yeah come here but
8:45 the the radial nerve disappears it
8:46 splits into superficial and deep
8:48 branches a superficial branch look it's
8:50 popping up here between the tendons and
8:52 then it's quite famously passing to the
8:55 the posterior hand here there's the
8:58 thumb these are the fingers so this is
9:00 the radion that the superficial branch
9:02 of the radial nerve here which means
9:05 that it's gonna carry sensory
9:08 innervation from from this region here
9:09 right the posterior part of the hand
9:13 around the thumb around here the what we
9:17 call this anatomical snuffbox that's the
9:18 one achoo
9:20 yeah so right now it's almost enough
9:21 boxing this part of the hand here so
9:23 that's radial nerve superficial branch
9:27 now the deep branch can we see the deep
9:31 deep branch no the deep branch goes deep
9:33 and the deep branch is going to be
9:35 responsible for innovating the muscles
9:37 of the posterior compartment of the
9:40 forearm that is the muscles that extend
9:46 your wrist right radial nerve so that's
9:48 the branch of the radial nerve is just
9:50 it's just passing back around again to
9:52 the posterior compartment of the forearm
9:54 it was innovating all of these guys all
9:57 right so that's the radial nerve right
9:58 now if I go back up to the top I said
10:01 there are 1 2 3 branches there the
10:05 second one the musculocutaneous nerve I
10:06 think about the name of that
10:09 musculocutaneous glut cutaneous means
10:11 it's gonna be motors and muscular stuff
10:14 and sensory from cue subcutaneous stuff
10:16 some skin stuff right the
10:19 musculocutaneous nerve is going to run
10:24 to the anterior compartment of the of
10:26 the upper arm this model doesn't come apart
10:28 apart
10:31 we man I think does what can we see here
10:44 these pectoralis minor he's biceps it's
10:48 coracobrachialis yeah because we're seen
10:51 Musto cutaneous diving up into here to
10:53 get underneath biceps so if we take
10:58 biceps off there we go that here's a the
11:01 proximal humerus here and there's the
11:04 musculocutaneous nerve so that's the job
11:05 of the musculocutaneous nervous to
11:09 innervate the flexors of the upper arm
11:12 and that's it so it's carrying to the
11:14 anterior compartment of the upper arm is
11:16 going away these three muscles here so
11:17 basically is gonna innervate the muscles
11:19 that flex the elbow biceps brachii
11:22 coracobrachialis and brachialis and
11:24 that's the end of it if it's muscular
11:28 job it does continue of course this is a
11:32 left arm right left arm here and we can
11:34 see it continuing when it pops out again
11:36 it disappears on here but not too
11:39 surprisingly because it's a cutaneous MA
11:41 a cutaneous nerve which means it because
11:42 the skin has been taken away
11:44 we've lost the cutaneous nerves as well
11:46 just like we've lost those those
11:48 superficial veins that we can we can see
11:52 in the skin of our arms right the
11:54 musculocutaneous nerve is going to
11:56 continue is the lateral cutaneous nerve
11:59 of the forearm which means it's gonna
12:02 it's gonna carry sensory innervation
12:09 from the so it's going to carry sensory
12:11 innervation from the skin and the
12:13 lateral part of the forearm here now the
12:20 radial nerve is going to I've got I've
12:23 got a fake nerve here now the radial
12:26 nerve okay if we stick with the left arm
12:29 so we saw the range of nerve is coming
12:31 around around here right before it comes
12:36 around the elbow it sends off a before
12:37 the radial nerve splits into the
12:39 superficial and deep branches
12:44 it gives off a a posterior cutaneous
12:48 nerve of the forearm like this and that
12:51 splits off a you know proximal to the
12:53 elbow so above the elbow and then gives
12:56 off a branch so the radial nerve and
12:58 this posterior continues near the
13:00 forearm is actually carrying the sensory
13:02 innervation from the posterior part of
13:03 the forearm and then the muscle of
13:05 cutaneous nerve is carrying sensory
13:07 innervation from the the lateral part of
13:08 the forearm through the lateral
13:11 cutaneous nerve the fourth all right so
13:13 we've got a medial cutaneous nerve to
13:16 discover later so that means that we
13:20 have taken care of the muscles of the
13:22 arm with the musculocutaneous nerve and
13:25 the radial nerve now we've still got the
13:29 median nerve and the ulnar nerve to deal
13:31 with and that's what we see here now
13:33 look this is biceps brachii remember
13:35 this is the right arm arms everywhere
13:38 this is this is the right arm
13:41 here's biceps brachii there's triceps
13:44 brachii si brachii brigham and the
13:46 artery the brachial artery is running in
13:49 this groove in between the two and
13:50 you've got we go in there
13:52 coracobrachialis whatever so you've got
13:53 the brachial artery running in this
13:55 groove which means it's very superficial
13:57 and we talked about this when we talked
13:59 about the arteries of the upper limb you
14:03 can you can get in here and feel the
14:05 pulse now where you feel the pulse where
14:09 you feel that artery you can also feel
14:12 you some other firm round structures
14:15 that are very nice to poke two of those
14:19 structures are the median nerve and the
14:22 ulnar nerve and you know where the ulnar
14:24 nerve goes because of your funny bone
14:26 right but the median nerve is following
14:29 the brachial artery this is the cubital
14:32 fossa here of the anterior elbow and it
14:35 the brachial artery is running around
14:37 anteriorly into the cubital fossa and
14:40 then it disappears behind these muscles
14:42 so here's pronator terrors and we start
14:43 to get into the muscles of the forearm
14:47 if we take those away we can see a
14:50 little bit more whoo right so
14:52 we get into the cubital fossa that
14:54 anterior part of the elbow you can see
14:56 the brachial artery comes around and
14:58 splits into ulnar and radial arteries
15:01 the median nerve comes around with it
15:04 before the median nerve before the
15:06 brachial artery splits the median nerve
15:09 then disappears beneath these muscles so
15:11 that goes away from it a little bit the
15:13 median nerve then is going to run into
15:16 the anterior compartment of the forearm
15:18 I've got to take off another muscle
15:20 layer to see it so we're with the same
15:22 thing quite deep here but there's the
15:24 median nerve there there's the ulnar
15:26 artery there's the radial artery so
15:29 we're very very deep the median nerve is
15:31 going to innervate all of the muscles of
15:33 the anterior compartment of the forearm
15:38 except for flexor carpi ulnaris which is
15:40 going to be innovated by V on the nerve
15:45 copy Oman and also we've got flexor
15:47 digitorum profundus that's the deep
15:50 muscle that flexes the fingers that's
15:51 going to be partially innervated by the
15:53 median nerve and partially innovated by
15:55 the ulnar nerve but the median nerve
15:57 otherwise is innovating all of the other
15:59 muscles of the anterior can pump to the
16:01 forum and those muscles are involved in
16:04 flexion of the wrist and and flexion of
16:07 the fingers right now the median nerve
16:10 continues and look it's still deep it's
16:13 still disappeared it's going to go deep
16:16 to the flexor retinaculum and at the
16:19 wrist which is which is there right
16:21 which means that the median nerve is
16:25 running through the carpal tunnel now if
16:29 we look at the carpal tunnel we've got
16:31 another video on that there's the bones
16:34 of the wrist and making a groove here
16:37 right and making a space and blood
16:38 vessels and the median nerve run through
16:47 it's going to innervate the muscles of
16:49 the thenar eminence these are the
16:51 muscles of the base of the thumb it's
16:53 also can we innovate the lumber cause I
16:58 think got video on that too and so the
17:01 median nerve then is it's sensitive to
17:02 being come
17:04 rest within the carpal tunnel it's a
17:07 carpal tunnel syndrome information of
17:08 the synovial bits and bobs in there
17:11 compression for carpal tunnel is likely
17:15 to affect the median nerve and the
17:19 median nerve then it's going to carry
17:21 sensory innervation from the skin on on
17:23 this side of the hand like the thumb
17:26 solid of the hand and over the top of
17:28 the fingers remember the radial nerve is
17:30 doing the other side of the hand
17:34 all right median nerve i've got i've got
17:35 a whole elearning thingy on this
17:38 somewhere which i made with some digital
17:40 meat very very talented digital media
17:43 students who wanna go so that's the
17:46 median nerve okay there's one left now
17:49 the big four let's put this back
17:53 together so the final nerve of the big
17:55 four is the ulnar nerve and the ulnar
17:58 nerve loss were up here again it's
17:59 running with the brachial artery it's
18:00 running with his collateral branch to
18:02 the elbow but the ulnar nerve the
18:03 important thing about the ulnar nerve is
18:06 that it's also in this in this gap here
18:11 but it runs posterior so the the medial
18:12 remember this is the right hand post
18:15 here it's the medial epicondyle of the
18:20 of the humerus so that means it's
18:24 running well there's the medial
18:27 epicondyle so it's running posterior to
18:28 the medial epicondyle around there and
18:31 you know this because when you bang your
18:33 funny bone here when you bang your
18:36 medial epicondyle it hurts and you get a
18:38 tingling shooting down your forearm on
18:41 this side to your little finger which
18:43 also then tells you what the ulnar nerve
18:46 does I think very nice to poke you you
18:49 can camp out Bait it we were the only
18:50 nerve then runs around the medial
18:54 epicondyle and it runs down here so we
18:57 can see that on the big arm model
19:01 remember this is a right hand still so
19:03 we lose the ulnar nerve here as it goes
19:05 deep we can't see it because it's
19:07 covered by these muscles it's safe again
19:10 down here it's vulnerable up here in the
19:12 arm in the forearm it's it's pretty deep
19:14 we can see it appear
19:16 came down here towards the wrists if I
19:20 if we dissect deep we'd go deep and take
19:21 all these muscle layers off there we go
19:23 there's the ulnar nerve running down
19:25 there so it's very much running on me
19:27 you know the the on the side of the ulna
19:29 and as I said it's going to innervate
19:32 flexor carpi ulnaris it's going to
19:35 contribute innovating flexor digitorum profundus
19:35 profundus
19:38 the deep flexor of the fingers in here
19:41 but look it's going into the hand you
19:43 can see it's going over the top of so
19:45 it's superficial to the flexor
19:47 retinaculum so the ulnar nerve is not
19:50 affected by carpal tunnel syndrome and
19:52 then it's um it's giving off a whole
19:57 bunch of branches into the hand and the
20:00 posterior hand here as well so it's
20:03 gonna the ulnar nerve is innovating most
20:05 of the intrinsic muscles of the hand the
20:06 median nerve is innovating these guys
20:10 over here in some of the lumbricals the
20:13 ulnar nerve is doing the rest and also
20:15 think about the skin that we haven't
20:20 innovated yet so the the divider is
20:22 typically halfway down the fourth finger
20:25 right so one to do so halfway down this
20:27 finger this side is innervated by the
20:30 median nerve this side is innovated by
20:33 the ulnar nerve and also post eerily
20:36 right so on the median radial nerve so
20:40 if you want to test if a cutaneous part
20:42 of these nerves are working you can just
20:45 you know test for sensation here radial
20:48 test for sensation here medial test for
20:52 sensation here on the nerve who's that
20:55 so those are big four it's difficult
20:57 with these models that you can't rotate
20:59 and stuff I mean I often use
21:01 computer-generated images for teaching
21:04 this along with these models because
21:06 it's difficult to see the roots but but
21:09 visualize how the musculocutaneous nerve
21:12 runs into the anterior compartment d2
21:15 biceps brachii how the radial nerve gets
21:16 around into the posterior compartment
21:19 and then comes around to the cubital
21:20 fossa then splits into deep and
21:22 superficial branches which carry on down
21:24 superficial is then going you know
21:26 that that region there and the deep is
21:28 going to innovate all of the muscles of
21:30 the posterior compartments just
21:33 visualize the the ulna and the median
21:35 nerves the median nerve staying in the
21:36 middle so it's coming around anterior to
21:38 the medial epicondyle it's getting to
21:40 the cubital fossa innovate all of the
21:43 muscles of the of the anterior
21:45 compartment all except one and a half
21:49 and then gets down into the the thenar
21:51 eminence the thumb and the hand biko
21:53 going through the carpal tunnel and then
21:55 visualize the ulnar nerve running around
21:57 posterior to the medial epicondyle of
22:00 the humerus and innovating flexor carpi
22:02 ulnaris in continuing down to innervate
22:04 most of the intrinsic muscles of the
22:09 hand flow right get the the shapes get
22:10 the flow that's the important thing you
22:11 read these descriptions in textbook
22:14 sounds very complicated visualize the
22:16 shapes it's not so bad so those are the
22:18 big four and while we were going through
22:20 there we've talked about a bunch of
22:22 cutaneous nerves but let's add a few
22:29 more on top on top cutaneous on top
22:32 superficial okay so if we're going to
22:36 talk about cutaneous nerves of the upper
22:38 limb I'm going to use pipe cleaners
22:40 because of course the skins be no moves
22:41 we've lost the cutaneous nose we see the
22:43 one we're dissecting and then we cut
22:45 them out generally the exilic nose it's
22:46 gonna renovate the deltoid muscle so
22:48 it's also going to give off a super
22:51 superior lateral cutaneous nerve of the
22:54 arm which is going to innervate the skin
22:57 around this same region bit further down
23:00 the radial are the radial nerve is going
23:02 to give off a cutaneous branch it's
23:04 gonna pop pipe through here and it's
23:05 going to win a which he'll be the
23:08 inferior cutaneous nerve of the arms
23:11 again innovating kind of an infertile
23:15 part of the skin of the of the arm the
23:16 radial nerve is also going to give off a
23:18 posterior cutaneous nerve of the arm
23:21 which is doing away the skin post here
23:26 really now a fun thing is medially there
23:31 are two medial cutaneous nerves which
23:32 comes straight off the brachial plexus
23:34 they come off the medial cord of the
23:37 brachial plexus up here and we have a
23:41 medial cutaneous nerve of the arm
23:44 running pretty much like this was with
23:45 the ulnar and the median nerve that we
23:47 were looking at and that's going to
23:49 carry sensory innervation from the
23:54 medial skin of the arm tell me something
23:56 else is fun there's a nerve called the
23:58 intercostal brachial nerve and the
24:02 intercostal brachial nerve is actually a
24:05 branch of the second intercostal nerve
24:08 it pops out here nice we're right in the
24:11 exilic and that into costo brachial into
24:15 costo so ribs brachial arm now ins Kosta
24:18 brachial nerve passes into the the
24:21 auxiliary region so it carries sensory
24:23 innervation from the axilla so guess
24:27 what the fun thing here is yeah if your
24:30 Anani suggests you could you could block
24:33 you can anesthetize in a block being
24:36 Tanya brachial plexus which shields a
24:38 numb the entire upper limb right but the
24:40 patient will he'll still have some
24:42 sation some sensation around here in the
24:45 exilic because that sensation is carried
24:48 by the intercostal brachial nerve which
24:51 is going from the thorax they're cooler
24:53 that's a good that's a good trait
24:56 question in it but there's otherwise
24:58 there's that medial cutaneous nerve of
25:00 the arm and then there is two pipe
25:02 cleaners there's another branch straight
25:05 from the brachial plexus a medial sorry
25:11 yeah a medial medial cutaneous nerve of
25:13 the forearm so that leave your
25:14 continuation over the four up comes
25:15 straight off the medial cord of the
25:17 brachial plexus runs all the way down
25:20 here with these guys and runs to the the
25:23 medial part of the forearm the lateral
25:26 cutaneous nerve of the forearm was a
25:30 continuation a bit long of the
25:33 musculocutaneous nerve right that's the
25:35 lateral part of forearm and then we saw
25:39 that the radial nerve gave off that
25:43 posterior cutaneous nerve of the forearm
25:45 innovating the skin on the posterior
25:50 forearm so there you go then
25:52 those are the nerves of the upper limb
25:54 there are a lot of nerves in the upper
25:57 limb the most important ones are those
25:58 four that we talked about
26:01 musculocutaneous ulna median radial
26:02 nerves and then we've talked about all
26:03 the cutaneous nerves
26:06 mostly to give you an idea of the
26:07 collection of cutaneous nerves in the
26:09 upper limb and which nerves they come
26:12 from those those two medial cutaneous
26:14 nerves of the arm in the forearm it's
26:15 pretty cool they come straight from the
26:16 brachial place and the gold way around
26:18 right the others is a kind of fairly
26:20 sensible cutaneous branches of the other
26:24 nerves anyway that was a lot wasn't it
26:27 well maybe we'll do the nerves of the
26:29 lower limb next time well maybe we'll
26:30 have a break and do something a bit more
26:32 straightforward anyway if I didn't do
26:33 the cutaneous nose I know if somebody
26:36 would have asked me - she's nice I might
26:38 be asked see you guys next week see you
26:40 next week as well [Music]