 Good day everybody. Dr. Sanjay Sanyal, Professor of Department Chair. This is going to be a distinction of the median nerve, right from its origin in the axilla, all the way down the arm, the cubital fossa, forearm, to the hand. This is the subangatever, this is the left side, I am standing on the left side and the camera person is on the left side. Just to bring up the speed, this is the axillary vein, which is thrombosed here. And this one, which I have picked up here, this is the axillary artery. We see this V-shaped structure here. This is the formation of the median nerve. So how is the median nerve formed? The median nerve is formed by two roots. This one is called the lateral root of the median nerve and this is called the median root of the median nerve. The lateral root of the median nerve comes from the lateral core of the brachial plexus and the median root of the median nerve comes from the medial core of the brachial plexus and the two of them unite to form the median nerve. At this juncture, I would like to show you a very interesting and important landmark. I have lifted up the ulnar nerve here, I have lifted up the median nerve here, and I have lifted up the musculoskeletal nerve here, and I have put them up like this. And you notice that they make a sort of an M, the ulnar nerve, the medial root of the median nerve, the lateral root of the median nerve, and the musculoskeletal. This M landmark is a very important landmark when we are doing the section of the axilla. So let us continue. So this is the formation of the median nerve. The median nerve initially is located just lateral to the brexillary artery. And then as it descends down, it comes in front of the brachial artery. And then as it descends further down, it comes medial to the brachial artery, and that is how it is located in the cubital fossa, which I am going to describe just now. The median nerve in the arm does not give any branches, and we can see that very clearly here. The only branch that it gives significant, which we cannot see though, are the branches to the elbow, those are the articular branches. In this respect, it resembles the ulnar nerve. Ulnar nerve also does not give any branches in the arm, it gives only particular branches to the elbow joint. Now let us take a look at the median nerve in the cubital fossa. So this is the median nerve that I have picked up here. This is the cubital fossa. The cubital fossa is bounded medially by the proentoterious muscle, this is the proentoterious muscle. Laterally, it is bounded by the brachioridialis, this is the brachioridialis, and therefore this is the depths of the cubital fossa. The flow of the cubital fossa is formed by the brachialis superiorly and further deep and down is formed by the supinator muscle. The contents of the cubital fossa are from medial to lateral. We have the median nerve, which I mentioned just now. The next structure is the brachial artery, which I have picked up here. Then we have the tendon of the biceps brachii, this is the tendon of the biceps brachii, and we can see this is the biceps aponeurosis, which we have cut, which was forming part of the roof of the cubital fossa. And the lateral most structure of the cubital fossa is this structure, this is the radial nerve. So therefore the contents are from medial to lateral. Medial nerve, brachial artery, biceps tendon, radial nerve, MBBR. So let's continue with the median nerve. In the cubital fossa, the median nerve can be injured in one of two ways, and both of them are very frequent in children. If a child falls on his outstretched hand, he can develop what is known as a supra condylar fracture across like this. And if there's an anterior dislocation, it can injure the median nerve and or the brachial artery. And the other injury is when there's an anterior dislocation of the elbow joint. This is an x-ray to show anterior dislocation of the elbow joint. These type of injuries, the first thing we have to check for is the radial pulse. If the radial pulse is absent and or if the finger is gold or there's no digital circulation, we should immediately take the child to the theater for reduction and decompression of the median nerve and or the brachial artery. Let's continue further. The median nerve after it exits through the cubital fossa. It passes between the two heads of this muscle, which I mentioned just now. This is the proentoteres muscle. The proentoteres has got two heads. One is the humeral head, which takes origin from the common flexor origin of the humerus and the other is the ulnar head. So it passes between the two heads of the proentoteres. Then after that, it passes through the two heads of the flexor digitalum superficialis. And this is the flexor digitalum superficialis. The flexor digitalum superficialis also has two heads. A humeral ulnar head and a radial head. The radial head is the oblique line, anterior oblique line of the radius. So the median nerve passes between the heads of two muscles, the proentoteres and the flexor digitalum superficialis. Here again, we have an entrapment syndrome. The median nerve can get entrapped between the two heads of the proentoteres. And that will produce what is known as a proentoteres syndrome, where there will be pain in the depths of the cubital fossa and there will be tingling numbness and distribution of the median nerve up to the palm, especially when we do a stress test. Let us continue with the course of the median nerve. Now we have come to the median nerve in the forearm. The median nerve runs in the neurovascular plane. The neurovascular plane is between the flexor digitalum superficialis, which is this muscle, and the flexor digitalum profundus, which is this muscle. So this is layer number two and this is layer number three. So this is the neurovascular plane and the median nerve runs in there. Here it gives an anterior-introcious nerve. The anterior-introcious nerve supplies part of the flexor digitalum profundus. It supplies the flexor pollicis longus, and it supplies the pronator quadratus. That is the supply of the anterior-introcious nerve, the branch of the median nerve. Here we can again have a syndrome called the anterior-introcious syndrome. If the anterior-introcious nerve is injured, then the person will not be able to do this sign, as we can see here. He will not be able to flex the distal phalanx of the thumb and the distal phalanx of the index finger, which is called the o-sign. And when you ask him to do this, instead his fingers will go like this. This is called the pinch sign. This is a sign of anterior-introcious nerve injury, the so-called anterior-introcious syndrome. To continue further, the median nerve then comes to the wrist, and this is the location of the median nerve that we can see here. Just before the wrist, just before the carpal tunnel, which we show just now, the median nerve has a very important relationship. This is the flexor carpai radialis tendon. In this particular cadaver, the pomerous longus tendon is missing. The median nerve is located between the flexor carpai radialis tendon and the pomerous longus tendon. So this is the location of the median nerve. And we can actually feel it in a living person when we ask the person to pinch the thumb and the little finger. This is the pomerous longus tendon. And just later to that is the flexor carpai radialis. The median nerve is located in between the two. And this is the location where anesthetists can give a nerve block of the median nerve to anesthetize a large portion of the palm and the digits for any surgical purpose. Thereafter, the median nerve passes through the carpal tunnel and we have opened up the carpal tunnel. We can see one cut edge of this tough structure where my finger is located. This is the flexor retiniculum and we can see how tough it is. And this is the other cut edge of the flexor retiniculum. So we can see the two cut edges of the flexor retiniculum and we have split it open. This is precisely the surgery that is done in carpal tunnel syndrome. And we have opened up the carpal tunnel and we can see the median nerve is passing through the carpal tunnel and I have lifted it up here. On entering the carpal tunnel, it divides into the following branches and we can see them clearly here. We can see a recurrent branch. This is going in the opposite direction. This is called the recurrent branch of the median nerve which supplies these muscles. These are the thin arm muscles. Namely, the abductor polices brevis, deep to that is the opponent's polices and the flexor polices brevis. Then we have these digital branches. They are the ones which supply the digits. They supply the thumb, the index finger, the middle finger and the lateral half of the ring finger and we can see the digital branches. Ideally, the median nerve is supposed to give a communication to the ulnar nerve but in this case, we cannot see the communication. This is the ulnar nerve that we can see here and there will be a communication which goes like that. This carpal tunnel is a very important place where the median nerve can be compressed because this carpal tunnel contains nine tendons. The four tendons of the flexor digital superficialis, the four tendons of the flexor digital profundus, the flexor polices longest, nine tendons, so therefore it is very crowded here and the median nerve, if it is compressed, it will produce numbness, tingling and peristicia of all these digits including the lateral half of the ring finger. The medial half of the ring finger and the middle finger will be spared because they are supplied by the ulnar nerve. Additionally, there will also be weakness of the thinner muscles because the median nerve is supplying the thinner muscles and we can see that here by means of this recurrent branch. However, the skin of the palm will be spared because the branch to the skin of the palm comes superficial to the carpal tunnel and therefore it does not go through the carpal tunnel. When we give digital blocks, we have to give digital block on adjacent sides of the digits in the inter-digital web space so therefore if we want to block the middle finger, we have to block this side and we have to block this side and so on and so forth. So we can see the full distribution of the median nerve. Injury to the median nerve will produce the following disabilities. Number one, there will be wasting of the thinner eminence and the hand will look flat like that of a monkey and that is referred to as a simian hand or the ape thumb deformity. The person will not be able to do this movement, that is opposition and that is a very serious disability because opposition is the one important action of the thumb which distinguishes the hand of the human from that of the monkeys. Another deformity that will be seen will be when the person is asked to make a fist, he will not be able to make a fist instead these three fingers because of the paralysis of the flexor digital superficialis and the profundus, these three fingers will remain like this. This is called the hand of benediction or the pope's hand. Third, the person will not be able to flex the distal phalanx of the index finger and the middle finger because these are supplied by the flexor digital profundus which is supplied by the median nerve. So these are some important disabilities that will happen if there's an injury to the median nerve. So we have seen the full course of the median nerve with the clinical correlations all the way from the axilla through the arm, through the cubital fossa, the forearm, the wrist, the carpal tunnel and the pump. So these are all the things which I wanted to show you. Thank you very much for watching. Dr. Sanjay Sanyal signing out. Mr. Kendal Kambabaj is the camera person. If you have any questions or comments, please put them in the comment section below. Have a nice day.