6. Ulnar Nerve | Upper Limb Anatomy | Dr. Azam | Medical Maven

Ajouté : 2026-05-15

[00:00:05]Hello my dear friends and now let's talk about the alna nerve. So in the major nerves category we have completed muscularcutaneous nerve and auxilary nerve. Now let's move on to the most important ones and uh that is your allnar median and radial nerve. Out of these three first let us learn about the alna nerve here guys.

[00:00:21]As I said you in whenever you learn about any nerve first of all write down the origin of the nerve here and origin I hope you all are perfect here. Alna nerve will be originating from the medial chord.

[00:00:35]Medial chord of brachal places and what is the pneumonic? The pneummonic for the medial chord will be M4 U. And here U stands for your alna nerve guys. So alan is originating from the medial cord of the braes. Then what is the root value of the ala nerve? I hope you remember it is having something exceptional there guys. C7, C8 and T1.

[00:00:56]C7, C8 and T1. So normally all the branches which are coming from the medial chord their root value will be C8 and T1 only. But Alana will be having like C7, C8 and T1 guys. Now after learning the origin and the root value, the next thing starts the most important thing that is your supply.

[00:01:13]Alana will be supplying to which muscles and we are going to study this one by one step by step. First we'll see in the arm then in the forearm then in the hand. Now first in the arm.

[00:01:25]Recall in your mind will alana now supply to any muscles in the arm?

[00:01:28]Absolutely no. Like how can you say so confidently guys? It is not supplying to any muscle in the arm. You can tell it like very confidently by using my golden rule. I said you all the muscles in the anterior compartment of the arm muscular cutaneous nerve and all the muscles in the posterior compartment of the arm radial nerve. That means there is no question of alanav. Alana is not supplying to any muscle in the arm. Then the next thing the alana will enter into the forearm. Okay. So in the arm it is not supplying to any muscle here.

[00:01:56]Then the next thing will be the forearm.

[00:01:59]Will Alana now supply to any muscle in the forearm here guys? Yes of course.

[00:02:03]Which compartment? In the anterior compartment. So Alana will be supplying to the muscles in the anterior compartment. But will it supply to all the muscles in the anterior compartment?

[00:02:11]No. We have seen in our golden rule all the muscles in the anterior compartment of the forearm will be supplied by two nerves. One is your alna nerve another one is media nerve. So we need to learn here out of all those flexar muscles present here which muscles are supplied by alna guys. So first remember that alna nerve will be supplying to medial one and a half muscles. Medial one and a half muscle of the anterior compartment.

[00:02:37]Now what is that one complete muscle?

[00:02:38]Yes, the medial most one that is flexar karpy alnaris muscle. Flexar karpy alnaris muscle. And another one more muscle which is supplied by alna nerve will be FDP guys. Flexar digitorum profundus. But as I said you one and a half that means alan nerve is not supplying to the entire FDP. It will be just supplied to the medial half of the FTP. Medial half of the FDP and of course without any doubt the lateral half will be taken care by medial nerve.

[00:03:02]Okay. So let us just make a note of all these things. So in the forearm alana will be supplying to medial one and a half muscles of anterior compartment.

[00:03:15]Okay, medial one and a half muscles of anterior compartment.

[00:03:19]Now what will be this one and a half muscle? Number one that will be your flexar carpy alnaris.

[00:03:27]Flexar carpalis muscle and number two will be the flexar digtorum profundus flexar digitorum profundus muscle guys that's fdp but remember it is not supplying to the entire fdp it is only supplying to the medial half of that one medial half of the fdp guys then what about the lateral half of the fdp lateral half will be taken care by the median nerve to again recall here can I call this fdp as a composite muzzle absolutely any muscle which is supplied by two nerves it will be definitely a composite muscle. So better we'll do one thing here. We'll just add a note here itself guys.

[00:04:04]So what about FDP flexar digtorum profendus muscle we can divide that fdp into two halves.

[00:04:12]One will be the medial half and another one will be the lateral half. The medial half of the fdp will be taken care by alnar nerve and the lateral half will be taken care by the media nerve. So therefore FDP you can add to the list of composite muscles guys or hybrid muscle. So in this manner what I will do is one by one like uh whatever hybrid muscles we are going to come across in the entire anatomy. We'll just keep on making a list of this one here. So fine now we actually like continuing with our allna nerve. We are done with the arm. In arm alla nerve is not supplying to any muscle and in the forearm it will be supplying to medial one and a half muscle. Comfortably done here. Now that Alana will be entering into the hand here sir and it will be supplying to certain muscles in the hand. Now guys I hope now you will 110% agree with me that's the reason why before itself I have actually completed all the muscles here. Now see here no much stress here no tension at all comfortably very calmly we are able to recall the names and we are able to write down here that's all. So similarly try to recall from the muscles of hand they're totally how many muscles guys 20 muscles but all the 20 muscles are not supplied by all nerve. Allna nerve will be actually supplying to 15 muscles out of that 20 like 15 muscles. Let us try to you know first of all understand here later on we'll make a note of that. So alna nerve will be coming from the medial side and it is going to pass like superficial to the flexoraculum and then it will be supplying to all the hypoththenar muscles. The digit minimi one hypoththenar muscle there are totally four of them. One is you know the flexar digital minimi abductor digital time minimi opponent's digital time minimi and then you have got the palar is bravis. So all those hypothalammas and then that alana will be also supplying to the third and fourth lumbrical the third and fourth lumbrical out of totally four lumbricals are there first second third and fourth only two the medial two will be supplied by laner then it'll be also taking care of all the introi the four palar introi and four dots roshi and then it'll be going on the other side on the other side one of the exception I even said you one also that is aductar policies guys so on the other side alna will be supplying to one of the the isar policies and it is going to go and end there. It is going to end in that one.

[00:06:22]That is the reason why it is said to be the graveyard of alna nerve.

[00:06:25]Understanding? So let me just summarize once more here guys and then we'll write down here. Come on you also try to tell it by yourself wherever you are studying. Alna nerve will be entering here supplying to all the hypoththenar then third and fourth lumbrical here and then all the interosi for palmar for dorsali. Then on the other side it will be supplying to one more muscle that is adductar policis adductar policus guys.

[00:06:46]So let us continue in the same sequence.

[00:06:48]Arm completed. Forearm completed. Now let us see. Alna will be supplying to which muscles in the hand.

[00:06:55]So it will be supplying to all the hypoththenar muscles?

[00:07:00]All the hypoththenar muscles guys. Okay.

[00:07:02]Then next number two it will be supplying to L3 and L4 that is your third and fourth lumbrical and then it'll be supplying to all the interosi the four palar and four dots interroshi.

[00:07:17]And then it'll be supplying to what guys the adductor. Adductar policis.

[00:07:23]And as I said you adductar policis is the last muscle to be supplied by alana.

[00:07:27]That means alana will go inside that and it will end there only. That is the reason why this adductar policis is said to be the graveyard.

[00:07:35]It is graveyard of your alana. Graveyard of all nav. Okay. Now my dear friends look there. Out of the 20 muscles of the hand almost like 15 muscles of the hand will be supplied by alan. That means alna nerve is the dominant nerve in the hand. It is a dominant nerve in the hand and that is the one which is controlling like majority of the movements of the hand. That is the reason why all those movements are required for playing musical instruments and all. I hope you are able to recall alanav is also said to be the musician's nerve guys. So that is the reason why alana is set to be the musician's nerve. Done. So we have comfortably completed the entire motor supply in the arm, forearm and the hand.

[00:08:07]All the muscles has been done here. And now what we'll do is after writing down all these things here now we'll try to make a simple schematic diagram of the alan nerve so that you retain that more nicely and along with that we'll also see the applied aspect of that one guys if there is an injury like high eleation and loweration of the alaner how will you differentiate there we'll see that okay so do it in the same sequence first make a note of all the muscles once you get that very clearly in your mind crystal clear then try to make a schematic diagram so that you can retain it for a longer time guys okay now just imagine here this one is the lower end of the humorous guys the lower end of the humorus it will be having that lateral epicondile and there will be a medial epicondile a prominent medial epicondile there now nerve it is not supplying to any musles in the arm okay what is going to happen so the nerve will just pass here it is not going to supply to any musles in the arm and then one more important point to make a note here it is going to pass behind the middle condile behind the middle epicondile so in this diagram also I'll try to you know incorporate more points CS. So that is the best way to learn step by step slowly slowly you keep on adding the points and learn everything at once doesn't make any sense. Okay. So now a learner is going to pass behind the middle epicondile and after that that aler will actually enter into the forearm.

[00:09:24]Now how it is entering into the forearm here guys. How is that a learner entering into the forearm? Now it's going to enter into the forearm by passing between the two heads of flexar karpy alnaris muscle here. So there will be flexar carpalis muscle. There will be two heads of that between the two heads of that it is going to pass and enter into the forearm guys. So it is going to pass between the two heads. I'm just writing here between the two heads of flexar karpy alnaris. Now you might be thinking like why sir stretching a lot here. Yes, there is a reason in this one when it is passing between the two heads of flexar carpnar is there guys. there itself.

[00:10:01]Yes, it is going to actually pass through a tunnel and that tunnel is said to be the cubital tunnel. Be very very careful with this one here. Don't get confused with the carpal tunnel here.

[00:10:13]It's cubital tunnel. Cubital tunnel. So alna nerve is going to pass between the two heads of the flexor carpal naris through the cubital tunnel. That's the reason why whenever you come come across a question cubital tunnel syndrome. Yes.

[00:10:24]What is the nerve involved there? It is alna nerve which is involved there guys.

[00:10:27]Compressed there or trapped there.

[00:10:29]understanding now. So basically it's entering into the forearm supplying one and a half muscle as I told you flexar carpelaris and not only flexar carpelaris it is also supplying to one more muscle that is fdp flexar digtorum profundus and we all know very well it will be supplying only to the medial half of flexar digtorum propundus medial half of flexar digum profundus now after that arm and the forearm is done arm is done the forearm is done now that alana will actually enter into what it will enter into our hand and And here also we have like something important to take a note about. There will be a flexar retinacculum here guys. There will be a flex retinacculum here. Okay, there will be a flex retinacculum here. And you got to decide. Okay, suppose if this is the flex retinacculum, you got to decide whether the nerve is actually passing superficial to that or deep to that one guys. And remember alnar nerve is the one which is going to pass superficial to the flexoracum. It's going to pass superficial to flex retinacculum. So alna nerve will pass superficial to flex retinacculum and enter into the hand.

[00:11:28]Now after entering into the hand it is dividing into two branches. One is the superficial branch and another one will be the D branch and that D branch will take a turn and go on the other side guys. So in the in the hand it will be actually divided into two branches here.

[00:11:42]One will be the superficial branch superficial branch and another one will be the deep branch.

[00:11:50]Fine. And always don't try to just you know keep on uh drawing on your books over there. try to even practically apply that means the ala nav is entering here and it is dividing into superficial and deep and deep branch is taking a turn and going on the other side it's actually taking a turn and going on the other side now out of these two remember the superficial branch is the one which will be supplying to palaris bravest muscle palaris bravest muscle so I hope you remember all the hypoththenar muscles and out of that one of the muscle will be just subcutaneous just below the skin here if you just reflect the skin even that muscle will also be gone so Just below the skin here superficially you'll be having palaris bravis muscle and that will be actually supplied by superficial branch of alna now guys and not only that remember it is also the superficial branch is also supplied into the skin the skin of medial one and a half hand I'll tell you the reason why I'm using the word here as complete hand here alnar now will be supplied the skin covering the medial one and a half complete hand here guys I mean to say even on the palar surface as as well as the dorsal surface. Understanding on the palmar surface, medial runar dig, the little finger and half of the ring finger and even the dorsome of the hand also guys. So we'll just try to make a small picture of this one here.

[00:13:06]For example, if this one will be your little finger, ring finger, the middle finger and the index finger and this will be the thumb here guys.

[00:13:16]And imagine this one to be your palar surface.

[00:13:22]Fine. Now in this only that medial one and a half the skin covering the medial oneup digits and as I said you not only the palmer surface even this the same is also on the dos dom of the hand guys that is the reason why I'm just mentioning the word there as complete you know medial one and a half hand there the skin of medial one and a half hand the palmer as well as dorsal aspect now once this is done here what about the D branch now D branch you don't have to worry about that one everything else you can just dump it over there it is taking care of everything else. So what is this D brand supplying to guys? Number one, it'll be supplying to all your hypoththenar muscles.

[00:14:01]All the remaining hypoththenar muscles.

[00:14:04]Fine. Why? Because palaris bra is the one which is taken care by superficial branch. So remaining all flexar digit minimi abductor digit minimi opponent's digit time minimi everything will be taken care by the D branch. And then after hypoththenar I told you that the D branch will also be supplying to the lumbricals and that is lumbrical number three and the lumbrical number four. So the medial two lumbricals lumbrical number three and four. And then it'll be supplying to all the intro.

[00:14:32]All interroshi the four palmer as well as the four dorsal intro are supplied by alanov only. And finally finally I told you after supplying to all of them it'll be going and ending in a muzzle that will be the adductor policus muscle. That's the graveyard of alano adductor policy muscle guys. It is ending there. So that's the entire story regarding the alanov made easy in a simple diagram.

[00:14:57]Okay. So you can just mention here this will be actually in the arm.

[00:15:03]Okay. And this part will be actually the forearm.

[00:15:08]And finally this will be in the hand guys.

[00:15:12]Fine. And one more thing you have to make a note here. Remember ala nerve is actually going to pass superficial to flexar retinaculum. I'm just writing in short here. Flexar retinaculum guys.

[00:15:25]Alanov is passing superficial to flex retinacculum. Qua and uh I believe that picture based memory like image based memory will be for long term. So if you just practice this you can never ever get confused in the alanov any question that might ask you guys. Now now after completing the entire normal thing regarding the alanov now let us see like what will be the injuries injuries of alanov here if it is injured then what will happen like how to differentiate we can actually divide the all of injury into two categories guys like the higher relation and the loweration fine. So first of all I'll tell you here in detail and after that we'll we'll we'll make a note of this one and I want you all to be like more alert now why because this is the most important part nowadays the trending thing the clinical uh clinical concepts are very much important nowadays so injuries are being tested very much in the exams so concentrate here guys alna nerve injuries we can divide into two categories one is higher another one is the lower leation either it can be injured near the elbow as I told you here cubital tunnel syndrome the alna nerve can be trapped between the two heads of flexor carpelaris or the ala nerve can be injured fine near the wrist and uh it can be like gy canal syndrome. I hope you know about the guans canal here which is like medial to piso hammit ligament. So it can be gyans canal syndrome or there can be laceration you know wrist injuries and all. So therefore the alanov injuries can be to high and the loweration but whenever you are learning about nerve injuries first of all try to find out like what is the main important feature of alnanov injury. If alanov is gone whether here or here I mean to say like higher leation of the alanab or the lower leation of the alana anywhere remember all these 15 muscles present in the hand will be gone. Now if these 15 muscles in the hand are gone then what will happen the hand will be actually converting into like this. What is this?

[00:17:04]This is claw hand. But is it like complete claw hand? No it is just a partial claw hand. Partial claw hand or else we can also call it as alnar claw hand guys. Okay. So you have to make sure that whenever alanav injury will be present the patient will always come to me with a partial claw hand or vice versa if any patient comes to you with a partial claw hand definitely it is which nerve involved alanav involved now what is the next challenge in front of you once the patient comes to you with a partial claw hand yes sir it is al nerve now the next challenge is whether it is injured here there is a lower leation or the high to differentiate that I'll tell you listen here guys if there is a lower of the al nerve if there is a lower leation of learn. If it is injured here near the wrist, then there will be partial claw hand. But remember here that these muscles are still working.

[00:17:51]Why? Because if the injury is here, all the muscles distal to that will be gone.

[00:17:55]Proximal to that before that the muscles are still working. Okay? So these muscles are actually spared. They're still working. Okay? They're not they're not involved in the injury here. So which muscle I'm speaking about? I'm mainly concerned about FDP. FDP, flexar digitorum. So flexar digitorum, you concentrate on that one. It's still working. So therefore if the ala nerve is injured here there will be clawing but remember the clawing will be more why because fdp flexar flexar digitorum profund is still working and therefore it'll flex and the clawing will be more concentrated at this point here okay now suppose if the alna nerve is injured here high elation highation what is happening here if this is injured here fcu is gone fdp is also gone and as well as all these 15 ms are also gone and because this 15 ms are gone here Again there'll be clawing but this time the clawing will be less. Why? Why? Because even FDP is also gone. So therefore if the FDP is gone here yes the flexion will be less and the clawing will be less. Now to now try to understand guys when there is a higherion highion the clawing is less and when there is a lower leion the clawing is more. So it is kind of paradox and this is actually said to be the alnar paradox. Crystal clear concept guys. So high leation there'll be less severe clawing and low leation there'll be more severe clawing is okay that is known as the alnar paradox. I hope the concept is crystal clear. Let's make a note of this one. So in this applied aspect alnar paradox.

[00:19:24]Now what is this allnar paradox guys?

[00:19:26]I'll write it in a simple manner.

[00:19:29]Highation and the lowation of alna nerve. And whenever there will be like higheration of the alnano what is going to happen sir? There will be less claw.

[00:19:41]And why there is less claw here? Why?

[00:19:43]Because fdp flexar digtorium profundus is involved here.

[00:19:50]Fine. And whenever there is a loweration of the alna nerve then there will be more claw.

[00:19:56]More claw. Why? What is the reason for this one guys? The reason is very simple. FDP is spared. It's still working. Fine and this gives a kind of opposite that is nothing but your allar paradox here. Hope it is very clear guys. And uh one more thing that you can include here what can be the reason what can be the reason for this hilation and the lowation. One common thing that you want to remember for hilation is cubital tunnel syndrome.

[00:20:21]Be very careful guys. I'm telling you again and again it's not carpel. It is cubital tunnel syndrome.

[00:20:26]Fine. And what is the reason for the lower leation? Loweration one of the reason can be gans canal syndrome. gyans canal syndrome.

[00:20:37]Fine. So I'm just making you write down the most like important ones that you have to at least remember. I'm not writing uh the list of all the reasons for the low and high legion. At least you have to know about this one guys. So that is entire thing regarding the alnanov the root value the origin the motor supply as well as sensory supply and then a beautiful schematic diagram so as to remember that one and then finally the applied aspect if there is injuries how to differentiate between the highation and the lowation guys that's all