 Welcome to our next dissection. My name is Dr. Sanjay Sanyal. I'm the professor and department chair of the National Medical Sciences. And the camera persons are Jenny Glover, Zellika Stewart, and Sahaiyya. I'm going to demonstrate whatever we can see about the brachial plexus, right from the origin to some of its branches. Take a look at what I'm showing you. The dissection extends from the neck all the way through the axilla to the arm. So let's see what we can see in this dissection. Take a look at this muscle here. This is the scalyneus anterior muscle. And just behind the scalyneus anterior muscle, this is the scalyneus posterior muscle. These two muscles, they are located in the neck. And this small space between the scalyneus anterior and the posterior, sorry, correct me, it's not the posterior, the scalyneus medius muscle. Scalyneus anterior and the scalyneus medius muscle, this small triangular space is referred to as the scalyne triangle. If you look closely at the scalyne triangle and where my finger is located, we can see some structures emerging through the scalyne triangle. These are the trunks of the brachial plexus. And we can see the upper trunk, the middle trunk, and the lower trunk. Upper trunk is formed by the union of C5 and C6 root, C7 root, and C8 and T1 root. These three are the upper, middle, and lower trunks. These three emerge between the scalyneus anterior and the scalyneus medius. What we also notice is the subclavian artery is also emerging from the, in front of the brachial plexus, also between the scalyne triangle. Now here there is an important clinical correlation, and that is referred to as the scalyne triangle. When abnormal insertion or attachment of the scalyne muscles can compress these trunks of the brachial plexus, one or more of these trunks, and or the subclavian artery. And they produce a constellation of symptoms which are referred to as the scalyne syndrome. Let's continue further. As we know, each trunk then divides into an anterior division and a posterior division. So the upper trunk is dividing into anterior and posterior division. The middle trunk also divides into an anterior and a posterior division. And the inferior trunk is also dividing into an anterior and a posterior division. So we can see the divisions here. Furthermore, we know that the posterior trunk of all the divisions, they unite. And they form what is known as the radial nerve. And we can see the radial nerve here. We shall follow the radial nerve further in our subsequent dissections. The cords of the brachial plexus have been cut. But the rest of the brachial plexus I shall show you. But we can see that the anterior divisions of the upper two trunks, they unite to form the lateral cord. And you can see part of the lateral cord here. And we can see a little bit of the cord of the lower trunk also. Having said that, let's continue down into the axilla and see what are the structures which we have been able to salvage. Let's take a look at this structure here, which is between my fingers. Take a look at this M-shaped structure here. This is an important landmark in axillary brachial plexus dissection. These are the terminal branches of the brachial plexus. From the lateral cord, we have two branches coming out. This is one limb of the M, which I refer to. And this is the musculocutaneous nerve. The other branch of the lateral cord, this is the lateral root of the median nerve. Now let's take a look at the medial cord. The medial cord also divides into two branches. This is the one branch, and this is another branch. This is the ulnar nerve, and this is the medial root of the median nerve, the medial root of the median nerve. So medial root and lateral root. The lateral root and the medial root of the median nerves, they unite to form the median nerve, which you can see going down. And finally, from the medial cord, the rest of the medial cord continues as the ulnar nerve. So therefore, this is the M, which I was referring to. Musculocutaneous nerve, the lateral root of the median nerve, the medial root of the median nerve, uniting to form the median nerve, and the ulnar nerve. The story will not be complete unless I show you this structure also, which we have been able to salvage. This structure that we see here, this is also a branch of the medial cord. And this is the medial cutaneous nerve of the arm and the medial cutaneous nerve of the forearm. This is the medial cutaneous nerve of the arm, this is medial cutaneous nerve of the forearm. And as you know, the medial cutaneous nerve from accompanies the basilic vein, which I'm going to tell you in my next video. So these are the structures of the brachial plexus starting from the trunks, the divisions, the cords and the branches. In my next section, I'm going to show you the axillary artery and the subclavian vein. Thank you very much for watching, ladies and gentlemen. Have a nice day.