 I'm holding the heart in my left hand. So this is the sternocostal surface of the heart which is formed mostly by the right ventricle and this is the diaphragmatic surface of the heart or the inferior surface of the heart which is formed by the left ventricle. So we have made an incision along the inferior border of the heart which also is formed mostly by the right ventricle and then we have continued the incision on the left margin of the heart which is formed by the left ventricle. Then we have made an incision on the anterior surface of the the sternocostal surface of the heart. And now I'm going to reflect this, show the interior of the right ventricle. So this is the interior of the right ventricle. We notice these ridged muscular part. These muscles, rich muscles are referred to as the trapeculae carnea. And if you trace them up, you find that this where my finger has gone in, this is the outflow of the pulmonary trunk. This is referred to as the infundibulum or the conus arteriosus. In the region of the outflow, we notice that the muscular portion disappears and it becomes smooth. Because wherever there is inflow or outflow of blood portion will be smooth to prevent turbulence. And the junction between the trapeculae carnea and the smooth portion is marked by a circular ridge. And that is known as the suprapentricular crest. The next thing you notice are the leaflets of the tricuspid valve and the cordae tendinae and the papillary muscles. Because there's a right side, there are three leaflets, three papillary muscles and three sets of cordae tendinae. Cordae tendinae are the ones which connect the leaflets to the papillary muscles. So this is the anterior leaflet, which I've lifted up. The anterior set of cordae tendinae attaching to the anterior papillary muscle. The one behind, this is the posterior valvular leaflet, posterior papillary muscles and the posterior cordae tendinae. And this is the interventricular septum, cordae tendinae which are attached to the interventricular septum, the papillary muscles. They refer to the septal leaflet of the tricuspid valve. So therefore the tricuspid valve has got anterior, posterior and septal. The next thing I would like to draw your attention to is this muscular band extending from the interventricular septum to the base of the anterior papillary muscle. This is referred to as the septal marginal trapeculae or the moderator band. This helps to regulate conduction fibers of the right bundle through the moderator band to the base of the anterior papillary muscle and coordinate the contraction of the anterior papillary muscle on the right side. The function of the papillary muscle is when the ventricle is contracting, the papillary muscles also contract and therefore they prevent prolapse of the leaflet of the valve into the atrium. These are the structures we notice on the right ventricle. I would like you to notice the thickness of the musculature of the walls of the right ventricle. This is the mitral valve on the left side, anterior cusp, posterior cusp and we can see the cordae tendinae attached to the papillary muscles. The most common pathology involving the mitral valve is what is known as mitral stenosis where there is narrowing of the mitral valve. The opposite condition is called mitral regurgitation where the valves do not close during systole and therefore blood moves from the left ventricle into the left atrium. So stenosis means narrowing, regurgitation means non-closure leading blood to flow in the opposite direction. We can have a similar pathology on the right side also. So this is the tricuspid valve. We can have tricuspid stenosis, tricuspid regurgitation. However, mitral stenosis is more common. Now let me mention a quick word about the pulmonary outflow itself. We see that the pulmonary outflow in this category is already open. These are the semilunar valves. The semilunar valves are called semilunar because they are half moon shaped. The free margin of the semilunar valves are referred to as the lunule and the central portion is slightly thick and that is referred to as the nodule. The nodules have showed a watertight closure. These valves they are referred to as the cusps. So therefore there are three pulmonary. There is one anterior, one right and one left. So this is the pulmonary outflow. The anterior one is the pulmonary outflow, the posterior one is the aortic outflow. Pulmonary outflow is also referred to as the infundibular. In the case of aortic outflow, we can see that the valves are closed already. Here the relationship is opposite. Here we have two anterior left and right and one posterior. Above that estimate of the semilunar valves to the respective wall either to the pulmonary or to the aorta. We see there's a small dilatation. That is referred to as the sinus. So in the case of aorta, this is referred to as the aortic sinus. In the case of the aortic sinus, they are more important functionally and clinically. This is the right aortic sinus and this is the left aortic sinus. These are the places which are responsible for dastrolic filling. That means during dastroly, when the valves are closed, these sinuses fill up with blood. The right aortic sinus gives passage to the right coronary artery and we can see the opening of the right coronary artery if we look very closely here and my instrument has gone in. This is referred to as the right coronary osteum. Similarly, on the left side, we have this left aortic sinus that gives opening to the left coronary artery. So during dastroly filling, it gets filled with blood and the coronary arteries get filled up with blood. And in the case of the aorta, the posterior aortic sinus does not have any coronary. In the case of the pulmonary arteries, the sinuses are not so functionally important. Again, we can get aortic stenosis and aortic regurgitation. In aortic stenosis, the blood does not flow out symmetrically and in regurgitation, blood flows back down into the left ventricle. Similarly, we can get pulmonary regurgitation and pulmonary stenosis. However, aortic stenosis is more common than pulmonary. The most common condition where you can get valvular pathology is atherosclerosis, ischemia or congenital defects. Though, of course, they can also be due to rheumatic heart disease. So these are some common defects which involve the aortic valve, pulmonary valve, tricuspid valve and mitral valve. The next point which I want to mention to you was about the location of hearing the sounds. Mitral valve sound is heard at the apex of the heart, which is in the fifth left intercostal space, one palm width from the midline. Tricuspid valve closure is heard in the left fourth intercostal space. Pulmonary valve closure is heard in the second left intercostal space and aortic valve closure is heard in the second right intercostal space. So these are some clinical correlations pertaining to the four valves of the heart.