 this is going to be a demonstration of the interior of the ventricles. I am 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 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 by the left ventricle and then we have made an incision on the anterior surface of the sternocostal surface of the heart and now I'm going to reflect this to show the interior of the right ventricle. So this is the interior of the right ventricle. We notice these rigid muscular part. These muscles, rich muscles are referred to as the trapecula carnea and if you trace them up we find that this where my finger has gone in this is the outflow of the pulmonary trunk. This is referred 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 whenever there is inflow or outflow of blood that portion will be smooth to prevent turbulence and the junction between the trapecula carnea and the smooth portion is marked by a circular ridge and that is known as the supraventricular crest. The next thing you notice are the leaflets of the try to speed valve and the corded tendinane and the papillary muscles because it's the right side there are three leaflets, three papillary muscles and three sets of corded tendinane. Corded tendinane are the ones which connect the leaflets to the papillary muscles. So this is the anterior leaflet which I have lifted up the anterior set of corded tendinane attaching to the anterior papillary muscle. The one behind this this is the posterior valvular leaflet posterior papillary muscles and the posterior corded tendinane and this is the interventricular septum. Corded tendinane which are attached to the interventricular septum the papillary muscles they refer to the septal leaflet of the try to speed valve. So therefore the try to speed 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 a septal marginal trabecular or the moderator band. This helps to regulate the 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. So 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. 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're 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 nodule has a watertight closure. These valves they are referred to as the cusps at the base where the cusps are attached to the walls just above that there is a small dilatation. These are referred to as the sinuses. So therefore there are three pulmonary sinuses. There is one anterior sinus, one right sinus and one left sinus. So this is the pulmonary outflow. Now I'm going to turn the heart a little bit to show you the interior of the left ventricle and as I've told you we have already made the decision and I'm reflecting the walls to show the interior of the left ventricle. Straight away we notice that the wall of the left ventricle is much thicker than the wall of the right ventricle. This is the wall of the right ventricle and this is the wall of the left ventricle. The left ventricle wall is three times as thick as the right ventricular wall. Again we can see the muscular portion inside which is known as the trapeculae carnea. The next thing I would like to draw your attention to are the cusps of the mitral valve. We can see only two cusps and I'm going to put my finger inside the left atrium and we can see it has come into the left ventricle. So therefore this is the anterior cusp. This is the posterior cusp and we can see that they're attached to the anterior papillary muscle by means of the caudate tendon a and we can see this is the posterior papillary muscles and these are the caudate tendon a. Again we can see the smooth outflow portion. This is the outflow portion and again I'm going to put my finger in and we can see it's coming into the aorta. That is referred to as the aortic vestibule which flows into the aortic orifice. Demarcation between the trapeculae carnea and the smooth outflow portion this is called the supraventricular crest. Now let me mention a few points about the semilunar valves of the aortic outflow or the aortic vestibule. The basic characteristics are the same. We can see the semilunar valves. These are the cusps of the valves. They are attached to the walls of the aorta and just above their attachment there is a small dilatation which is referred to as the aortic sinuses. The free margins of the valves are referred to as lunule and the central portion is referred to as the nodule. In this particular cadaver the aortic valve is already closed but we can separate them. These dilatations in the case of aorta here we have two anterior one posterior so this is the right anterior this is the left anterior aortic sinus. In the right anterior aortic sinus we have this opening where my probe has gone in and that is known as the right coronary ostium and we can see that the probe has come into the right coronary artery. Similarly in the left aortic sinus there is another ostium which opens into the left coronary artery so this is the left coronary ostium. The posterior aortic sinus is referred to as the non-coronary sinus because no coronary artery arises from that. Now I'm going to show you an important hemodynamic feature. I put one finger inside the left atrium and my finger has come into the left ventricle and I would like you to notice the direction of my index finger. I'm going to put my next finger inside the outflow and I'm going to bring it out through the aorta. We notice that the inflow to the ventricle is vertically inside and the outflow is vertically outside. So therefore the blood flows vertically into the left ventricle and flows vertically out. So as it flows out it makes a 180 degrees bend. Now let's come to the right side. Again I'm going to put my finger in the atrium and I'm going to bring it into the right ventricle and I'm going to put my other finger in the outflow of the right ventricle so we can see that my two fingers are making a 90 degrees angle so the inflow into the right ventricle from the atrium is in this axis it is horizontal. The outflow from the right ventricle is vertical so therefore the blood makes a 90 degrees bend in the right ventricle to flow out of the pulmonary trunk. The next thing I would like to draw your attention to is my right index finger is on the left ventricle it's in the interventricular septum the muscular part and my left index finger is in the right ventricle again in the muscular part of the interventricular septum so therefore my two fingers are on the interventricular septum. This can be a site of ventricular septal defect. Usually a small ventricular septal defect in the muscular part closes by itself so therefore it is not requiring any intervention. However there is a portion of the interventricular septum which is not visible here and that is known as the membranous part of the interventricular septum and there can be a defect and that is known as a ventricular septal defect which is by far the most common congenital cardiac defect and if such a defect is present then it requires surgical closure. There are many congenital anomalies pertaining to the heart but these are just a few of them which we wanted to mention. Thank you very much for watching. Dr. Sanger signing out. David O is the camera person. If you have any questions or comments please put them in the comment section below. Have a nice day.