 Today we are going to talk about the chest wall, the thoracic cage. I am Dr. Sanjay Sanyal, Professor Department Chair. So what we see here in front of us is the thoracic cage or the so-called rib cage which has been harvested from this cadaver here. Now we have reversed the chest wall and you are seeing the anterior chest wall from inside out. You are seeing the inner surface of the sternum. And we notice two great vessels running one on either side of the sternum. These are the internal thoracic artery and the internal thoracic vein. The internal thoracic also known as the internal mammary artery is lateral. The internal thoracic vein is medium. The internal thoracic artery comes from the subclavian artery. And we can see the other cut end from here. This is the branch from the subclavian artery on this side and this is the branch from the subclavian artery on the other side. These are the cut ends of the same internal thoracic artery that we see here and here. And they come down below the sixth rib. They divide into two terminal divisions. This is the musculophrenic branch and this is the superior epigastric. We can see the same thing on this side also. The superior epigastric and the musculophrenic. So that brings me to the next point. The internal thoracic artery arrives to the anterior intercostal arteries. Two of them in each space. Up to the sixth space. So this is the first rib, second rib, third rib, fourth rib, fifth rib, sixth rib. Up to the sixth space the anterior intercostal arteries are given up by the internal thoracic artery. The seventh, eighth and ninth spaces are not given by the and internal thoracic instead they're given out by the musculophrenic artery. The seventh, eighth and ninth spaces are given out by the musculophrenic artery. And then it continues and supplies the diaphragm. Superior epigastric goes to the anterior abdominal wall. So that is about the internal thoracic artery. Now let's take a look at the internal thoracic vein which I told you on the medial side and you can see it very clearly here. The internal thoracic veins they drain into this vein that we see here. This is the brachiocephalic vein. The left brachiocephalic vein drains the left internal thoracic and the right brachiocephalic vein drains the right internal thoracic. This below the second rip if you look very closely you will find that the internal thoracic veins are venaecometantes. But as they go higher up they merge and they become one distinct vein and then they drain into the brachiocephalic vein on either side. At this juncture I need to mention one important clinical correlation. When we do a coronary artery bypass either in coronary artery blockage one of the methods of doing it is to take the left internal thoracic artery and separate it at its lower end and anastomose it to the heart coronary artery. That is known as the lima bypass left internal mammary artery bypass. It saves the surgeon from doing two anastomoses because one end is already attached to the subclavian artery the other end is only has to be anastomose to the coronary artery beyond the blockage. So this is a very useful method of coronary artery bypass surgeon. We have removed the lungs from here and we can see the posterior chest wall and we can see that the posterior intercostal arteries and the posterior intercostal veins the posterior intercostal arteries they all come out from the thoracic aorta which is on this side here most of them except the first and the second which come out from the supreme and the superior cost to cervical trunk. The intercostal veins on the right side they drain into this structure here this is called azygous vein. On the left side they drain into the left brachiocephalic vein, left accessory hemeasygous vein and hemeasygous vein three different structures. Now let me come and show you a few other clinical points. Now if you take a close look these are the intercostal spaces. On the anterior aspect we have two intercostal vessels coming out from the inter thoracic artery. On the posterior aspect we have initially one intercostal vessel but as it comes it gives a collateral branch which comes anteriorly and anastomoses with the anterior. These two needles mark the approximate location of the intercostal vessels and the nerves the main and the collateral. The main intercostal neurovascular structures they run in relation to the lower border of the rib above in a special area known as the costal groove and this marks the location of that and this needle marks the location of the collateral. So that brings us to an important clinical correlation. If we want to give intercostal nerve block we have to block the main neurovascular structure here which is in relation to the lower border of the rib above and we have to block the collaterals which are in relation to the upper border of the rib below. Another important clinical correlation is when we are doing a thoracentesis that is aspiration plural tap or plural aspiration in case of collection of fluid in the plural space. In that situation because we know that each intercostal space has got two sets of neurovascular structures one in this relation and one in this relation our needle should go further away from the lower border of the rib above and closer to the upper border of the rib below so this should be the approximate location of our needle for doing thoracentesis. Ideally it is done in the fifth intercostal space in the mid-axillary line but this should be the location of the thoracentesis further away from the lower border of the rib above closer to the upper border of the rib below so that we spare both the neurovascular structures especially the main ones. Now I'll give you an overview of thoracotomy. If you take a close look at the cartilaginous portion on this side I made an edge shaped incision even on this side I made an edge shaped incision and then I have reflected the pericondrium and I have reflected the pericondrium similarly on this side if you look closely I have reflected out the pericondrium here on this side and reflected the pericondrium on this side we reflect the pericondrium and then we restrict the cartilage under the pericondrium and that is an approach what is known as anterior thoracotomy. In contrast we can also do a posterior lateral thoracotomy I'm showing it from inside but we do it from outside what we do is we cut the periosteum of the rib and we reflect the periosteum we restrict out the rib and we go in the space left by the rib and that is called the posterior lateral thoracotomy. So this is about the chest wall and its important salient features if there are any questions or comments put them in the comment section below have a nice day Dr. Sanjay Sanyal signing out. Hey guys thanks for watching make sure you like this video and click the subscribe button.