 This is a quick demonstration of the break complexes in the axilla. So just to bring you up to speed, this is the pectoralis major which is one of the boundaries that anterior wall of the axilla. I am reflecting the pectoralis major, this is the pectoralis minor which also forms the anterior wall of the axilla. Now I am going to reflect the pectoralis minor roles. This is the posterior wall of the axilla. This is the latissimus dorsi muscle here. The next muscle that we see here, this is the teres major and the next muscle that we see here is the subscapularis. So these constitute the posterior wall of the axilla. This is the lateral wall of the axilla and this chest wall intercostal muscles and the cirrhitis anterior constitute the medial wall of the axilla. Having mentioned that, let me tell you the break complexes. In order to understand the break complexes, we have to demonstrate what is known as the M landmark. So let us take out the M landmark here. This is the classical M landmark which I have lifted up and we can see that it is in the form of an M. This is one limb of the M and this is the other limb of the M. This is the musculocutaneous nerve arising from the lateral core of the break complexes. This is the lateral root of the median nerve. This is the medial root of the median nerve both of them unite from the median nerve and this is the ulnar nerve which is arising from the medial core of the break complexes. So having identified the M landmark, now we know that this is the lateral core of the break complexes and this is the medial core of the break complexes. So what are the branches that we can see from the lateral core of the break complexes? At this juncture we must remember that we are in the axilla and we know that the roots and trunks of the break complexes are in the neck. The divisions of the break complexes are in the cervical axillary canal so therefore these three portions we cannot see them in this dissection. So here we can see only the cords and the terminal branches and the sum of the collateral branches. So this is the lateral core of the break complexes because it is situated lateral to the axillary artery and arising from the lateral core of the break complexes we have this nerve which is coming out and it is supplying the pectoralis major. This is the lateral pectoral nerve. This pierces the claustrophobic membrane and it supplies the pectoralis major. So this is arising from the lateral core of the break complexes. This is the lateral core of the break complexes. This is the pectoralis major muscle which is being supplied by the lateral pectoral nerve. We can also see a communication from the lateral pectoral nerve to the medial pectoral nerve which I shall demonstrate to you just now. What are the other branches from the lateral core of the break complexes? We can see this nerve here. This is the musculocutaneous nerve which I shall trace in another dissection. So these are the two branches that we can see from the lateral core of the break complexes. Now let's take a look at the medial core of the break complexes. This is the medial core of the break complexes because it is situated medial to the axillary artery. Arising from the medial core of the break complexes. First of all, we can see this nerve here. This is the ulnar nerve. This ulnar nerve, it descends down on the medial side of the arm and it goes behind the medial intermuscular septum and after that it goes behind the medial epicondyle and it goes into the forearm. Apart from that, the other branches from the medial core of the break complexes are this one. This is the medial pectoral nerve and as I mentioned a little earlier this is a communication from the lateral pectoral nerve to the medial pectoral nerve and the medial pectoral nerve supplies the pectoralis minor muscle from deep inside. And after it supplies the pectoralis minor, it pierces the pectoralis minor as you can see here and then it goes to supply the pectoralis major. So therefore, the medial pectoral nerve supplies both pectoralis minor and major and the lateral pectoral nerve supplies only the pectoralis major. major receives both from medial and lateral. The next branch that we can see from the medial cord is this one. Ideally we should have seen two such nerves. One, the upper one is the medial cutaneous nerve of the arm and the lower one should have been medial cutaneous nerve of the forearm but in this case we see only one branch. In all probability part of this will supply the medial cutaneous nerve of the arm and the rest of it will continue as the medial cutaneous nerve of the forearm and that's why it is so thick here. So these are the other branches which are coming from the medial cord of the brachial plexus. These are all the collateral branches and that brings me to the final cord of the brachial plexus which is situated posterior to the axillary artery and that is the posterior cord of the brachial plexus. The posterior cord of the brachial plexus continues and it divides into two principal terminal branches and we can see the two principal terminal branches here. The larger terminal branch is the radial nerve and the smaller terminal branch is the axillary nerve. So these are the two principal terminal branches of the posterior cord and incidentally we can see the posterior cord is receiving a communication from the medial cord and that is this communication here. Apart from these two terminal branches the posterior cord also gives the following branches and let's trace them. The posterior cord gives rise to this first branch that we can see here. This is the upper subscapular or which supplies the subscapularist muscle. The next branch that it gives out is this one here. This is the thoracodorsal nerve and we can see by tracing the thoracodorsal nerve when we trace the thoracodorsal nerve all the way down from here and I'm tracing it it goes and supplies the latsomers dorsal. And the next branch is this one. This is the lower subscapular nerve which supplies both the subscapularist muscle as well as the TD's major muscle. Since we are on the muscle nerve supplying the medial wall and the posterior wall this is one branch that we can see which is actually arising from the roots of the brachial plexus namely C567 root but it comes down and it runs on the lateral side of the chest wall. This is the long thoracic nerve or Bell which supplies the serratus anterior muscle. These two nerves the long thoracic nerve or Bell and the thoracodorsal nerve the first one supplying the serratus anterior and the second one supplying the latsomers dorsal. These two nerves have to be carefully safeguarded during axillary dissection when you are doing mastectomy for breast cancer and doing an axillary dissection for the lymph nodes we have to safeguard these two nerves. Injury to the long thoracic nerve will produce paralysis of the serratus anterior and beginning of the scapula and injury to the thoracodorsal nerve will cause paralysis of the latsomers dorsal. Apart from that of course any other nerve can also be injured but these two nerves are specially prone to injury because they are further lower down and these are the ones which come in the region of our dissection. So these are the important collateral branches that we can see. One thing we must remember that the branches which come out from the brachial plexus proper they are called the collateral branches and the branches which come out from the end of the brachial plexus namely the musculocutaneous the median nerve the axillary nerve radial nerve and the ulnar nerve these are the terminal branches of the brachial plexus these are strictly speaking not part of the brachial plexus. Final point to be noted is that arising from the root of the brachial plexus apart from the long thoracic nerve or Bell which I have already mentioned we also have another nerve called the dorsal scapula nerve arising from C5. We cannot see that here because as I said the root and the trunks of the brachial plexus are located in the neck. The dorsal scapula nerve supplies the levator scapulae rhombus major and rhombus minor. Another nerve which comes out from the upper trunk of the brachial plexus is the supra scapula nerve which also we cannot see because it is located in the cervical axillary canal and in the neck and the nerve to the subclavius. So these are the structures which we cannot see however the long thoracic nerve as I mentioned though it is arising from the root but it comes to the axilla therefore we can see it. So these are the all the structures which are visible in the axillary dissection. Thank you very much for watching. Have a nice day. Dr. Sanjay Sanyal, Sanyagore.