 Good day, ladies and gentlemen. Welcome to our next section of the neck. My name is Dr. Sanjeev Sanyal, Professor and Department Chair. This time, we are going to demonstrate the subclavian artery and the scalyne triangle and some of the other structures that we have exposed after removing the sternocleidomastoid muscle on either side of the neck. This structure that you see in front of you, this is the brachosophalic trunk. And you can see the brachosophalic trunk is arising from the arch of the aorta. This is the arch of the aorta. So, brachosophalic trunk. The brachosophalic trunk divides into the right subclavian artery and the right common carotid artery. So, let us focus on the subclavian artery. On the left side, the common carotid artery rises directly from the arch of the aorta and after that we can see behind that is the subclavian artery on the left side. So, let us focus on the subclavian artery on the right side. This has got more branches, though I am going to show the relevant structures on the left side also. So, let us focus on the subclavian artery on the right side. So, this is the subclavian artery arising from the brachosophalic trunk. And we know that the subclavian artery is divided into three parts. The subclavian artery is divided into three parts by this muscle here. This is the skelliness anterior muscle. It rises from the cervical vertebra and it gets inserted into the first rib. And this skelliness anterior muscle divides the subclavian artery into a first part which is before the skelliness anterior, a second part which is behind the skelliness anterior and a third part which you can see coming out here. So, these are the three parts of the subclavian artery and after the outer part of the first rib, the subclavian artery becomes the axillary artery which comes into the axilla. Let us take a look at the branches in the first part. The first part has got three branches and we can see some of those branches. This is the first branch, the internal thoracic artery. It has been cut in the lower part because this is the one which runs on either side of the sternum down into the thorax. The next branch that we see of the subclavian artery is this one. This is the vertebral artery. And the vertebral artery, as you know, it goes up in the pyramidal space between the skelliness anterior and another muscle here which is known as the longest coli. And it goes through the apex of the pyramidal space and it then enters the transverse foramen of C6 and goes up. So, this is the vertebral artery. And the third one is the thyrosurvicar trunk and this is the remnant of the thyrosurvicar trunk. Thyrosurvicar trunk actually is a little short and it has got multiple branches. And few of those branches we can see. One of that is visible here and this is the inferior thyroid artery. The other branch that you can see is the transverse cervical. The next branch is the suprascapular which is not visible here. And the other one is the ascending cervical. So, these are the ascending cervical and the inferior thyroid artery. Ascending cervical and the inferior thyroid artery are the two terminal branches. And you can see inferior thyroid artery and the ascending cervical. Okay, so these are the branches from the first part. Not visible here, but from the second part we have the costusurvicar trunk coming out which supplies the first supramintopostal artery and it also supplies the deep cervical arteries. The third part of the subclavian artery usually does not have any branches, but sometimes the dorsal cervical artery or the suprascapular artery can arise from the third part of the subclavian artery. Having said that, let me mention some important points about the course of the subclavian artery itself. We will again come back to the skeletal anterior muscle here. We notice that the skeletal anterior muscle as we have mentioned runs behind the skeletal anterior muscle, subclavian artery. And in so doing, it comes through a triangular space which is called the skeleton triangle. This is the skeletal anterior muscle and behind that is the skeletal medius muscle. This is the triangular space and this is bounded by the skeletal anterior muscle in front, skeletal medius muscle behind which also gets inserted into the first rib and the first rib itself and this is called the skeletal triangle. This is a very narrow space and through this space emerges four structures. One is the subclavian artery which we have already mentioned. The other three structures are the trunks of the brachial plexus and you can see the three trunks of the brachial plexus. The upper trunk, the middle trunk and the lower trunk. The upper trunk is formed by the union of C5C6 root, C7 root and C81 root. And we know that each trunk then divides into an anterior and a posterior division and you can see in this each trunk. The upper trunk is dividing into an anterior and posterior division. The middle trunk is dividing into an anterior and posterior division and the lower trunk is also dividing into an anterior and posterior division. And we also know that all the posterior divisions unite and you can see the posterior and the posterior. We united from the posterior cord of the brachial plexus. The anterior divisions of the upper and the middle trunk form the lateral core to the brachial plexus which you can see here and the anterior division of the medial lowest trunk forms the medial core to the brachial plexus which you can see here. So these are the things which we can see here in this. What is the significance of this chelene triangle? This chelene triangle is so narrow that you can compress one or more of these structures namely the trunks of the brachial plexus as are the subclavian artery producing what is known as the chelene syndrome. So this begs a question what about the subclavian vein? The subclavian vein is spared this problem of chelene syndrome because the subclavian vein runs anterior to the chelene anterior muscle and you can see the chelene subclavian vein here. Cut portion of the subclavian vein is visible here. It is running in front of the chelene anterior muscle while the subclavian artery is running behind the chelene anterior muscle. So therefore the subclavian vein does not get compressed by the chelene anterior syndrome and the subclavian vein we know very well as you can see here it continues and it unites with the internal jugular vein. This is the internal jugular vein and it forms the at this is called the venous angle which occurs at the level of the sternocleavicular joint and here it forms the brachiocephalic vein the right brachiocephalic vein. So this is the course of the subclavian vein subclavian artery the chelene triangle. Let us show the same thing on the other side just for ease of understanding. Let us pick up from where we left off in this side. This is the remnant of the left subclavian vein and this is the subclavian vein. What about the chelene triangle itself to show that I have to reflect this instrument and you can see these are the structures which are coming out through the chelene triangle on this side. We can see that these this is the upper trunk, middle trunk and the lower trunk of the brachial plexus on this side. This is the chelene's anterior muscle on the left side and this is the cut portion of the subclavian artery. So we can see that this is the chelene triangle on the left side. Subclavian vein again to show you arise runs in front of the chelene's anterior muscle. So for the subclavian vein does not get compressed and to continue with the story the left subclavian vein also unites with the this vein that you can see here is the internal jugular vein and it forms union occurs at the level of the left venous angle which is again at the level of the sternoclavicular joint and the left brachial cephalic vein runs obliquely and therefore it is about twice as long as the right brachial cephalic vein. It runs in front of the great vessels and then it unites with the opposite side brachial cephalic vein to form the superior vena keva and this union occurs at the level of the first rib and the superior vena keva then continues down till the third rib and then it enters into the right atrium. So we have seen the entire course of the subclavian artery, subclavian vein, the roots of the brachial plexus, the chelene's anterior, the chelene's posterior, the chelene triangle both on the right side and on the left side. Thank you very much for watching ladies and gentlemen. Have a nice day. Dr. Sanjay Sanyal signing out.