 This is going to be a demonstration of the right coronary artery, so let's take a look at the origin of the right coronary artery. It takes origin from the right aortic coronary sinus where my probe is pointing and this is the coronary artery right side as it comes out. In the initial part of its course it is hidden under the right oracle. So now that you have detected the right oracle we can see the course of the coronary artery in the anterior part of the right coronary groove. It continues on the right side of the coronary groove and I am going to turn the heart gradually and now we can see it is in the posterior part of the right coronary groove and here it is known as the right posterior coronary artery. At this place this is the region of the crux of the heart where the posterior interventory groove meets with the coronary groove. In the region of the crux of the heart the right coronary artery makes an almost 90 degrees bend downwards and here it becomes known as the posterior descending artery and it descends down in the posterior part of the interventory groove and it stops at the lower part of the posterior interventory groove. So this is the full course of the right coronary artery. Now let us take a look at the branches of the right coronary artery. This is the first branch. This is called the anterior branch of the right atrium and this anterior branch of the right atrium in 60% of the population gives a branch to the sinoatrial node. So that is the first branch. Then we have the multiple unnamed branches to the right ventricle and to the right atrium because it is a major supplier of the right ventricle and the right atrium. Right coronary artery as it is travelling from the anterior coronary groove to the posterior coronary groove it also gives a branch on the right margin of the heart and we can see that here a part of that is visible here. This is known as the right marginal artery and this right marginal artery runs in a complement with this vein here. This is the small cardiac vein. As it comes on the posterior aspect in this region if you look very carefully we can see it is giving a branch here. This is the branch which goes inside and it supplies the atrium ventricular bundle of his and it also supplies the AV node in 80% of the population. And in this particular cadaver dissection we can notice that the right posterior descending artery before it continues as the PDA it is also giving two separate big branches to the diaphragmatic or the inferior surface of the heart which is the left ventricle. They are all coming from the right coronary artery. So therefore the carry home message is that the posterior descending artery which runs in the interventricular septum it is a major supplier of the inferior or the diaphragmatic surface of the heart which is formed mostly by the left ventricle. And occlusion of the PDA here will produce diaphragmatic or inferior surface infarction. The posterior descending artery also gives multiple septal branches which go into the interventricular septum. And it supplies the posterior one third of the interventricular septum. So these are the full distribution of the right coronary artery. Now let's mention a few clinical correlations pertaining to the right coronary artery itself. In approximately 18 to 20% of the population the right coronary artery is dominant and therefore it supplies a large part of the heart not only the right side but also the left ventricle. Those cases are known as dominant RCA. In another 15% of the population the right coronary artery is deficient. It is either very small or it is even absent in which case the large part of the heart is supplied by the LCA. Both these variants are very dangerous because if there is any occlusion of the single dominant vessel then it can produce what is known as global myocardial infarction which can be life-threatening. So that is about the distribution of the right coronary artery. Now let's take a look at the distribution of the left coronary artery. Again let's start from the aortic sinus here. This is the left aortic coronary sinus and this is the opening which is known as the left coronary ostium. In this normal situation also the beginning part of its course it is covered by the left oracle. So we are separating the left oracle and we are separating the pulmonary trunk and once we do so we can see the main left coronary artery. The left coronary artery as it comes down before it enters into the coronary groove it divides into two major principal branches and let's take a look at them. This is one branch. This is the circumflex artery and other branch is this one. This is the anterior intraventricular artery also known as the left anterior descending artery or LAD for short. The LAD runs down in the anterior intraventricular groove and we can notice something very prominent about it. It has got a highly tortuous course. This is the feature of arteries in anywhere in the body where there is motion because here the ventricular wall is in motion and therefore to compensate for the motion the artery is tortuous and then it winds around the apex of the heart which is located here and then it runs into the posterior intraventricular groove a little bit but it stops short of the posterior descending artery. So this is the end of the anterior descending artery. This anterior descending artery gives the following branches and we can see them. The first branch that we can see here is this one. This is the diagonal one. We can see it one more diagonal here this diagonal two. In many patients we can have diagonal one, diagonal two or diagonal three. This supplies the majority of the left ventricular. The rest of the anterior descending artery as it descends down it supplies the anterior two thirds of the intraventricular septum and it also supplies the atrium ventricular bundle of his and it also supplies the right and the left bundles. So the anterior descending artery is the major supplier of the intraventricular septum namely anterior two thirds. The point to be remembered is that the anterior descending artery does not make a sensible anastomosis with the posterior descending artery. It stops short. Now let's take a look at the next large branch of the left coronary artery and that is this one. This is the circumflex artery. The circumflex artery runs in the left coronary groove and it goes into the posterior part of the left coronary groove. Before it goes to the posterior part it gives off this branch here and this is known as the left marginal artery or in clinical practice we call it the obtuse marginal OM. In this we can see only one but in many other situations we can have more than one when it is referred to as OM1, OM2, etc. This also supplies the left margin of the heart which is found by the left ventricle and then the main circumflex artery continues in the coronary groove and it runs and it supplies again the left ventricle and we can see the branches supplying the left ventricle. This circumflex artery also gives a branch to the atrioventricular bundle of his. So therefore the atrioventricular bundle of his gets supplied from the circumflex artery, the posterior descending artery and anterior descending artery. So these are the various branches of the coronary circulation that we can see here. So that is all for now about the coronary circulation. Thank you very much for watching. If you have any questions or comments please put them in the comment section below. Dr. Sanjay Sanyal, Sanyal. Have a nice day.