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Sorry, I have everyone. Uh Thanks for coming along. Uh I'm James. Uh I'm one of the committee members for cardio. So, and uh today I'll hopefully be going through the second part of our teaching series. Um Last week was kicked off with the first part of cardiac anatomy, which is kind of considering the external aspects. And uh this week we'll now be considering the intrinsic aspects of the heart. Um So I will just start to share the presentation then. Um hopefully a few more people will join, but uh I'll get started and let's see. OK. So hopefully you guys can see my screen and hear me. OK. Um Yeah. So, uh we're cardio. So then uh we're gonna be running a teaching series kind of on every aspect of the basics of the heart and then disease and treatments. So we're hoping to get a few experts in as well. And then towards the latter half of the year, um we're hopefully going to be uh covering some thoracic anatomy. So, looking at the lungs. Um So, yeah, so this is um the second part of cardiac anatomy and this will kind of finish us So today, uh we're gonna be going through the atria for both left and right, then the ventricles, uh then we'll consider the fibro skeleton of the heart ATRIO ventricular valves. So your uh tricuspid and your mitral semi linear, which are your um pulmonary and your aortic and then have a brief look at the intrinsic conduction system. So before we kind of get stuck into anything, then um we'll just have a brief overview of the heart. So you will get blood coming into the Rite aid, Jim from the superior vena cava and the inferior vena cava. And it will then travel from the right atrium through the tricuspid valve and into the right ventricle and then from the right ventricle, uh it'll travel up through um this kind of uh Conus arteriosis area will go in through the pulmonary valve into the pulmonary trunk here and will then pass into the lungs uh to be oxygenated or to oxygenate the blood uh via the pulmonary arteries. And then blood will return to the heart from the lungs from these vessels here, which are your pulmonary veins. And these pulmonary veins will kind of feed into the posterior aspect of the left atrium. And from the left atrium, it'll go to the bicuspid valve then into the left ventricle and then it will go uh up and out through uh the aortic valve and then into the aorta and into the systemic circulation. So we're going to consider the internal aspects of the heart first in this whole lecture. So first, we're going to have a look at the Rite Aid Jim um with the right atrium, uh it receives the oxygenated blood and it receives it from three vessels or three kind of areas. So the SP Vena cava, which is this vessel up here, uh It's returning blood basically from the head and arms down. Uh the inferior indicator them is this big vessel from the bottom here. This is just retiring blood from the lower half of your body. And then lastly here, we have the coronary sinus. And you can maybe see, well, you can just about see the opening of the coronary sinus here. This is simply returning uh the blood to the right atrium from all of the cardiac veins. So that's just um your coronary circulation, returning the blood back in. Uh you can't quite see it. Well, you can see slightly here. Uh Next, there's looking at the right auricle or what you would call the right atrial appendage. And these can be considered like almost the the ears of the heart. So there'll be these kind of structures that will kind of stick out in a almost an Antero medial direction and uh well super interiorly. So this is kind of where it's facing. So this kind of helps you to orientate yourself with the heart. Uh considering them as well, there's two important nodes include uh found in the Rite aid, Jim. So you have your sinoatrial node um which will kind of be uh up this direction close towards the, where the SPC is and your atrioventricular node, which will be down more towards the tricuspid valve. And we'll kind of talk about that a bit later. So we'll just continue to maybe have a brief look at uh the aspects of the ra dream. So next time in the right a gym, you have this rough area and then you have these smooth areas and really it's you have these packed in net muscles and peck muscles is just kind of uh found along the anterior wall. So what we have here is kind of uh a diagram which has been cut to reflect that anterior wall of the heart. So we can see this uh muscular pectin, very pectinate muscle and all this is is just an array of parallel muscular columns. So it's kind of this roughened surface in the heart and separating this roughened surface of the heart um from the smooth walls of the venous compartment. Is this uh ridge, this muscular ridge here which is called the Crista terminalis. And it's crescent shaped and it kind of runs from the superior to the inferior vena cava and the uh the uh sinus of the vena cava. And it kind of separates this roughened area from then this um smooth area. So we'll have a look at this diagram and just uh go through it. So for the right a gym, then we have our superior vena cava bringing blood in. We have our inferior Vena cava. We have this uh pectinate muscle here which is separated from the smooth muscle or sorry, the smooth walls of the right, a gym uh by the Crista Terminalis. Uh And then I think we're going to move on to the next parts just now. So whenever we consider there's something called an interatrial septum and all that basically means is that there's a, a wall between both the left and the right left and right atria. And between this wall, you can kind of see this shallow depression or shallow oval depression. And what we have here is really a kind of a remnant of the fetal heart, which would have been the fore mono valley because in the fetal heart, um the blood isn't going to the lungs because it's already been oxygenated by uh the mother. So you have this kind of shunt that will allow blood to pass from the right atrium and to the left atrium. And in adulthood, um this kind of uh ovale will close and be termed the fossa ovalis. So it, it's just fossil uh the shallow depression here. Next, then uh there's kind of two other vs that you maybe don't know much about, but it's maybe interesting to try and just look at them anyway. So for the in fear of any of them, there is a valve to stop blood from going back down and it is called the station valve. And it's located just here next in uh the coronary sinus. There's also a valve for it and it's, it's a be valve and it's just located there. So we've kind of, we have covered the right a gym. Then now we're going to go through this tricuspid valve and we're going to have a look at the right ventricle. So the right ventricle will receive deoxygenated blood from the right atrium and this will be through traveling through. So from the right atrium through this tricuspid valve, which we'll talk about in a bit also. And then the right right ventricle will see blood and its function really is to kind of pump blood from the ventricle into the pulmonary trunk, which is located here. And within this right ventricle limb, we have three papillary muscles. So we have our anterior papillary muscle. You have her posterior papillary muscle here, also termed inferior. And we then have our septal papillary muscle. And these are just kind of these outgrowths of the internal muscular wall of the right ventricle. And they will be attached to the tricuspid valve located here by these uh Cor tendinea or these tendinous cords. These tendinous cords will essentially stop the tricuspid valve from prolapsing back into the right atrium whenever the ventricle contracts. So this valve will close. And what happens here is the uh papillary muscles along with the tendinous cords will kind of stop the valves from bursting back into the right atrium. So it'll kind of hold it in place and we'll move on to the next aspect. But just before I do, this is just a slightly better demonstration of uh what the right or looks like on the heart. So that's out right atrial pen, sir. So we're going to have a look at the rest of the right ventricle limb. So you have these trabeculae carnea. So these are these kind of uh muscular elevations that are found more mainly on the apical aspects of the wall. Um Whenever we refer to the apex and the heart, we're referring down at this area down at the bottom here. So this is the apex of the heart. So you get these kind of these muscular elevations down towards that area and it's important not to get confused with the. So the tuberculi carnea are always located in the ventricles, whereas the pectinate muscles that roughened appearance is always in the atrium. So just be careful with that. Next time, we're going to have a look at the Conus arteriosis and the Conus arteriosis is located kind of in the infundibulum and the infantum is just this kind of smooth region which is leading up to the pulmonary trunk. So if you're wanting to be able to force blood out efficiently, you want to have this nice smooth area. So it'll go out uh through this pulmonary valve. So up here, we have this Conus arteriosis. So it doesn't have any of this roughened muscle, just a nice smooth area that allow blood to pass out into the palmary trunk and then into the palm art to be oxygenated. So next, then we have what is called this supraventricular crest. And really, it's just a ridge in the heart or around a accentuation which will separate this trabeculate car from this infundibular, which is the Conus arteriosus. So kind of along here. Ok. Next, then there's what maybe looks like a papillary muscle or like a trabeculae Coron, but it's actually quite special. So it's a septomarginal trabecula. And this septomarginal trabecula will pass from the um interventricular septum and the interventricular septum is really just this wall of muscle. Well, not all muscle, but this wall between both the right and the left ventricle. And uh what happens here is there's electrical signals or electrical fibers that will pass down this uh ventricular septum. And what happens here is the septum, marginal trabecula will come from the septum or the interventricular septum and it will transmit a branch of the right atrioventricular bundle. So it will bring this uh action potential from the interventricular septum. So it's bringing the, the uh propagating this action potential from here and bringing it all the way over to the anterior papillary muscle. So it's just passing on this electrical signal to life or contraction of the anterior papillary. So we've covered the right side of the heart. Now, we're going to have a look at the left side of the heart. And first of all, we're going to begin with the left atrium. So the left atrium, it receives oxygenated blood from the pulmonary veins and there's four pulmonary veins there. And uh you maybe can't see the other bits but uh four pulmonary veins and they come from the lungs and the left atrium can really be considered to be at the uh the posterior aspect of the base of the heart. So at the base of the heart, you're thinking that's the left atrium as well. Uh while the right atrium had an atrial appendage, so it is the left and you can see this left auricle or left atrial appendage here and it has pect in it muscle like was like what was found in the uh right atrium. And you can kind of see in this di where hopefully appreciate that there is these kind of this roughened appearance of this pack in it muscle. So these array of muscular columns. Uh so we briefly talked about her pulmonary veins, but in the kind of the posterior aspect of the left atrium, you will have these four coronary ostia and ostia just means kind of an opening or a hole. So this allows the blood to be fed into the left atrium. Uh We then have the sinus of the pulmonary veins, sinus is just kind of this dilatation. But at the posterior aspect here, you can appreciate that that's a nice smooth wall and this just allows the blood to flow in and then go down through this mitral valve into the left ventricle. And like we had a look at on the other side, you can see this uh fomon ovale. So this is the um uh a remnant of the er yeah, so the fore and ovale sorry is what is occurred in the um fetal heart, whereas this is the fossa ovalis. So this is closed over. So we've moved on from the uh left atrium. Then now we're going to consider the left ventricle. Uh on this diagram, you can see slightly better that there's four pulmonary veins here. So you've got your left pulmonary veins and then your right pulmonary veins and the blood will essentially go from the left atrium. There's oxygenated blood is returned to the heart will go through the left atrium through this mitral valve and then go into the left ventricle here. And the function of the left ventricle then is to pump blood into the systemic circulation. And what is meant by that is essentially the blood from here will be pumped out through the aorta and then out to the rest of the body. So you've got your pulmonary circulation for that uh is fed by your pulmonary arteries and then your systemic circulation is going to the rest of your body. And hopefully, you can see here from this diagram that the left ventricle has these thick muscular walls and it's needed to generate a high pressure. So to kind of build up this pressure head and then pump blood all around the rest of your body. So this is why it has these thick walls and it's thicker than the right ventricle walls. So whenever I look at papillary muscles again, um so the mitral valve has kind of two leaflets. And for those two leaflets, you have your anterior or your superior papillary muscles located here and then you have the posterior or your inferior papillary muscles. And they just attach on via these tendinous cords to the mitral valve to stop the prolapse of the leaflets back into the left atrium during ventricular systole. So he was just trying to hold those in place. So next, we're just going to have a look at the trabecular car. So they were present in the right ventricle also. And then in the left ventricle too. Again, it's these muscular elevations that you can see here. And they're found on the apical aspects of the internal walls and apical is just meaning towards the apex of it's just this bit along here. So you have these muscular edges and they are found down there. So, like the Conus arteriosus of the right ventricle, the left ventricle has a smooth area leading out to its uh kind of outflow tract and it's an area that is inferior to the aortic orifice. All that means is an area just below uh where the aortic valve is or uh yeah, where the aortic valve is. And it's essentially these fibrous walls that kind of allow for a smooth flow out into the aorta. And just to reemphasize the apex is located here and it's an anteroinferior extremity. And normally you would feel for this at the fifth intercostal space in the mid curricular line. So we've kind of covered both of the atria and both of the ventricles. So now we're gonna have a few questions then um which will hopefully kind of reinforce what we've covered. So what is the name of the internal structure that separates the right atrium into two parts, the sinus of an arum? So this is just talking about the smooth part of the right atrium and the atrium proper, which is talking about this kind of roughened area or roughened appearance. So there's a, the Crista terminalis b, the sulcus terminalis C the fossil valis D, the moderator band or E the super ventricular crest. So for these, I'm just gonna start the poll, I'll leave it up for a bit and hopefully get a few responses and then after that, I can kind of chat through. So that should be the pull up. Now, if you want to ask any questions or if anything is not clear as well, just put it under the chart. Um And then hopefully it can be addressed, just wait for a few more responses. So there's nine questions, right? That would be good if you can maybe have a go at it, go at it. OK. So that's the first question. So this internal structure that separates the smooth part. So your kind of venous component from your pint muscle. This is the crista terminalis. So this is found in the right atrium and this is the kind of muscular ridge that separates the um separates the rough air from the smooth area and it kind of goes in a most re ship from the superior vena cava to the inferior vena cava. So second question then uh the shallow depression found on the interatrial septum is a remnant of which embryonic structure, bulbus cordis, primitive atrium, sinus, stenosis, ductus arteriosus or the foraminal wallet. I will put the po now wait for a few more responses. Give another few seconds. OK. I'll close the pool here and share the answer. So for this one, then uh the shallow depression on the endo arial septum is the for a ovale. So the Fermon ovale uh and the embryological circulation allows blood to go from the right atrium to the left atrium. That's a shunt because the lungs are bypassed because they aren't able to oxygenate anything. So it's just about getting the blood through. So the fa valley um will then in an adult be termed the fossa ovalis because it closes over and it will, it's a remnant whereby it shows this shallow depression. Now, and in some people, they can still have that hole in their heart. And it's termed a patent for em and ovale. So now we're going to have a look at the fiber skeleton of the heart and it's maybe not something that people consider that often, but it's important to understand. So the fiber skeleton of heart is the cardiac skeleton. Um and it's consisting of four fiber strings and there'll be also be membranous portions of the septa. And importantly, it's located at the base of the ventricle. So diagram that will hopefully kind of explain that. So it's between the atria and the ventricles. So it has these four fiber strings. So you have uh one here for the pulmonary valve, one here for the aortic valve. You then have one here for your mitral and you have one here for your tricuspid. So that's your right fibrous annulus, left, left fibrous annulus. Um You've got your one for your aortic and one for your pulmonary. So these fibrous rings are really just dense, regular connective tissue and it kind of forms this framework to allow the valve to form and keep the kind of the orifice open and it essentially just encircled it. So it gives it this structure unless to hold open, unless if you didn't have this kind of cardiac skeleton, the heart would be just basically a bag. Um So what kind of connects these fibrous rings? Is these fibrous trigone? And you have two fibrous trigone. So you have your left fibrous trigone located here. This is kind of between the mitral and the um aortic valve and you then have your um right fibrous trigo located here and it's kind of in between your um once again your mitral and your aortic and your tricuspid as well and which we will come to you later. Uh You can see there's an opening here and this is for the bundle of his and the cardiac uh skeleton also is kind of insulator whereby no electrical signals should be able to pass from the atria down to the ventricles unless it goes through this opening for the bundle of this. Although in some patients, there can be a bit of a problem whereby signals can get through elsewhere and that causes the problem, isn't it? So, the fibrous ts then are both left, which is located here on the right. And these just interact these fibrous rings and form a structural support for the rings and also for the kind of the cardiac or the myocardium. So the heart muscle to attach to. So hopefully, this will be a slightly better diagram just to point out what's what so we have in blue here. This is the cardiac skeleton and what we have here is our pulmonary valve. So this is the fiber strength of the pulmonary valve. You have your fiber strength of the aortic valve. So your aortic valve is located here and you have your left atrioventricular ring. And this is for the mitral valve and you have your right atrioventricular ring and this is for the tricuspid valve. And as you can see here, there's the atrioventricular bundle or the bundle of his. So that's an opening there with our right fibrous trigone there and our left fibrous tw there. So in this, you can kind of appreciate slightly better that it's really between the right and left atrioventricular ring where the right fibrous tag one is located. So we've covered uh the cardiac skeleton and the atrium and the ventricles. Now we're gonna have a look at the valves. So we have our atrioventricular valves here. So ATRIO ventricular valve, it's in the name, they're found between the atria and the ventricles and there is two of them. So we have our Tricuspid valve. So our tricuspid valve is on the right, between the right atrium and the right ventricle. So it's located here, we then have our mitral valve or what's termed our bicuspid valve. So it's termed bicuspid because it has two leaflets and the right one then has termed the tricuspid V, it has three leaflets. But if you go back to the mitral valve, uh it's between the left atrium and the left ventricle and the composition of these valves or the valve leaflets. So it's kind of this white aspect here is it has a fibrous core that gives it a bit of structure within an endocardial lining. So that's just your endothelium will lining. So the tricuspid valve then is between the right atrium and the right ventricle and there's three leaflets to it. So we have our superior, we have our inferior and our septal. So as you can see here, we have our pepto um methods, but these also correspond to our papillary muscles. So we have our anterior papillary muscles and these will go to the anterior cusp. We have our septal pilary muscles which will go to your septal cusp. And we then have our uh inferior or posterior uh papillary muscle that go to the posterior cusp there. So, between the right, a right ventricle and its function is to prevent the backflow of blood from the right ventricle during ventricular systole. That might be slightly better than I appreciate here. There's your three leaflets. So your ter post here and sap for your next thing is the mitral valve and it has two leaflets. So you have your anterior or aortic and your posterior leaflet. So as you can see here, your posteriorly is there, your anterior leaflet is there. And because there's two leaflets will correspondingly be two papillary muscles in. So we have our superior or anterolateral papillary muscles here and they'll connect to that one. And then we have our inferior or posterior and these muscles will go to the posterior cusp and it's fine between the left atrium and the left ventricle. And it prevents the backflow of blood uh from the left ventricle into the left atrium. So it stops blood from going back up into here uh during uh ventricular systole. So we've had a look at the atrioventricular valves. Now, we're going to consider the semilunar valves and there are two semilunar valves. We have a pulmonary valve and this is found between the right ventricle and the pulmonary trunk. The aortic valve then is between the left ventricle and the aorta. And once again, the composition of these valves is just a fibrous core with an endothelial endothelial lining. So, here we have our uh pulmonary valve and here we have our aortic valve and I'm just going to talk a bit more about them uh in the next slides. So for a pulmonary valve, then uh we have three leaflets. Ok. So we have an anterior, what's this? Here? We have a right and then we have a left and it's between the right ventricle and the pulmonary trunk and it prevents the backflow of blood from the pulmonary arteries or really the pulmonary trunk uh into the right ventricle. So if we just have a slight, better look here, so we've got our three cups. Um you have these aspects here where they both join together. Um They have a kind of shoes and this will form what is called a commissure. And then at the very, uh, inferiormost aspect of the cusp, you'll have the deer and you'll hear, uh, cardiologists are really surgeons, talk about this. You'll go from your, uh, commissure up here to your aer we then have our nodules. Um, and these nodules are just thickened portions kind of in the middle of these leaflets. And at either side of these nodules, then you have the line, the line and these are just kind of reinforced edges there. And as you can see, this is kind of uh located at the junction between uh where the pulmonary talk starts and uh where the right ventricle kind of ends, you can see it forms a sinus. So the blood will just fall back. Uh and this is during a ventricular uh not ventricular. Yeah. So whenever ventricular systole is stopped and you have diastole, you will then have the blood. So the pressure in the pulmonary trunk will be greater than in the right ventricle. So the blood will want to fall back down into the right ventricle, but this is stopped by this valve. So it'll fill up these pulmonary sinuses. Next. Um which is slightly different. We're gonna have like at the aortic valve, it does have three leaflets, but they're named differently. And this is based upon the coronary arteries that kind of branch off of them. So we have our right coronary uh leaflet, which is located here. We have our left coronary leaflet, which is located here and then quite easily, we have our noncoronary or posterior leaflet. And these are named based upon the ostia for the coronary artery. So, as you can see here, this is the left coronary as the left coronary ostia is found there which the left coronary artery will come from. We then have the right because the right corne art is located here. what's the right coronary artery will come off from? And because there's no coronary artery here, it's just turned non coronary, that's between the left ventricle and the aortic root, um or aorta and it will prevent the backflow of blood from the aorta. So, and diastole then. So after ventricular systole, so when the ventricles have relaxed, the pressure in the aorta will be greater than in the left ventricle. And so blood will want to fall all the way back down into the left ventricle. So the aortic valve will stop this. So the aortic sinuses will become filled. But instead of just closing the valve, what will happen here is the right and left coronary sinuses or aortic sinuses, sorry will be uh filled with blood. And whenever they fill with blood, that will allow the coronary arteries to be, be perfused, then to allow the coronaries to perfuse the heart muscle to the cardiac muscle. And again, you have these fibrous nodules of arantius along with their inulae here and they can appreciate the commissure aspect uh here. So that's just the fusion of the leaflets together and then the naders at kind of the lower most aspect of these leaflets. So I'm just going to show a few images from the top down to show you what it looks like whenever these um when they are open. So this is atrial cysto. So in this, we have an open tricuspid a mitral valve and this just allows you to kind of appreciate a superior view of the heart. So you can see your liquid. So um you have your three leaflets here for your tricuspid three, for your bicuspid. And because it's um atrial cysto, uh your semi linear valves are then closed. This image here is showing what is happening uh during ventricular systole. So this is when the ventricles contract. So whenever the ventricles contract, um you're gonna have blood going out to the aortic valve and the pulmonary valve into the pulmonary and systemic circulations, but you will then have the um atrioventricular valves. So your tricuspid and your mitral closing, that's to stop the backflow or the regurgitation of blood or not. Yes, the regurgitation of blood into the atria. So we've kind of had a chat about the valves. It's important to maybe have a look at where the valves are placed in and then how to best listen to them because that's what you're concerned with whenever you're doing a Precordium exam. So we have our aortic valve here are pumping involved here. Our tricuspid valve here and our left uh intraventricular, also called your mitral valve here. And these valves do have uh surface projections, but you will listen to the valves in a different area then where they're found on their surface projections. So you have these a patient sites and this is just due to the direction of blood flow whenever these valves close. So the sound will kind of be carried along. So there's a slightly better diagram which I'll show next for this. So um this is just showing me where the valves are and these areas of kind of where the blood goes. And this diagram is just giving you a few, if you heard a murmur at that site, it might be due to one of these differentials though. And there's a table next which I'll just briefly talk through the locations of these. So for the aortic then where it actually projects to is where on the surface anatomy, if you have a look at the left sternal border, the third rib, that's what that's found. Pulmonary is the left sternal border, third costal cartilage, the mitral is found the left 4th 5th, intercostal space, space and tricuspid down is the sternum uh with the fifth costal cartilage, but most people aren't really concerned with that. And they want to know exactly where do you listen to the valves? So where the valves are and where you listen to them is slightly different. So this is kind of more clinically relevant and important. So if you want to auscultate to get a fancy word to listen, listen to the aortic valve. It's the right second intercostal space in the sternal margin. So that's here there, sorry. So right second intercostal space, sternal margin. So you listen there there with the pulmonary valve. Then if you want to listen to this, that it is the left second intercostal space, sternal margin. So there, so that second across space, sternal margin. So to listen to the mitral, it's the left fifth intercostal space in the midclavicular line, which is here to the mitral to the left fifth endos space in the mid line. And then tricuspid is the left fifth intercostal space roughly uh at the sternal margin. So, Tricuspid out of the left fifth or fourth inter space and that is at the sternal margin. So that's just these are the different sites that we'll uh listen to the heart for or listen for any murmurs for. And uh it's always good to know those. So you have a few more questions now. So uh how many papillary muscles are present in the right ventricle? And I will put the pull up now. So you think about what the name of the valve is between the right atrium and the right ventricle. And that will tell you how many papillary muscles are present and give it another few seconds, a few more responses. OK. So I will start pulling now. So for this one, it is three papillary muscles. So just consider that you've got your tricuspid valve there. And for each uh valve leaflet, you have a papillary muscle that corresponds to it. So there's three in the right ventricle. So think about the name of the valve. And can you tell me how many leaflets compose the mitral valve? So we'll give it a few seconds for that. So how many leaflets compose of mitral valves? Give it a bit more time? Ok. Ok. So for this one, then the mitral valve, another name for the mitral valve is the bicuspid valve. And bicuspid means that there's two leaflets. Ok. So there's three leaflets for the tricuspid valve, which is between the right atrium and right ventricle between the left and left ventricle is your bicuspid valve for your mitral valve. So it's two leaflets all done. Um Next time. So if you want to listen to the heart, so you want to auscultate in which area is it best to auscultate? The aortic valve? Is it the left second, intercostal space, sternal margin, left, fifth, intercostal space like your line, the right second intercostal space, sternal margin or the left fifth, intercostal space, sternal margin. Let's see, Paul isn't working for that one. Sorry. Um So I'm maybe just give you a few seconds and then just put the answer up if you're feeling brave, you can put it on the top. Ok. So if you wanted to auscultate the aortic valve, you would listen in the right second intercostal space, sternal margin. And this is just where kind of the direction of the blood flow would be going to the aorta. So the sun would be carried and that was where you hear it best. So you've got your aortic pulmonary tricuspid and then mitral. So we've had a look at the atria, the ventricles, the fibrous skeleton of the heart. Um We've then had a look at the atrioventricular valves and the semilunar valves. Lastly, we're going to have a look at the intrinsic conduction system of the heart. And this is really just the um specialized fibers in the heart that allow an action potential to be generated and then be propagated around the heart to allow for a kind of coordinated contraction to get your um atria contracting, go dying and then get your ventricles contracted. So the intrinsic conduction conduction system will initiate and control the contraction of the myocardium. So it's kind of this organized contraction and it's these uh specialized cardiac muscle fibers which will initiate and conduct these impulses. So this diagram and another one will flash up in a second. Uh It's allowing you to see where these kind of signals pass to and where they pass along. So we have their sign of a note here. This is where things will start. And then from there, it will go down to the atrioventricular node, which if you can remember from the cardiac skeleton, there was an opening for this uh for the bundle of hiss. Uh So it'll go through the interventricular bundle and the bundle his to your left and or left and right bundle branches. And from there, I'll pass back up on the ventricles and we've got these purkinje fibers along here. So this diagram is just kind of colored to correspond to an ECG. So here in the green, from the Sinu, a note down to the atrioventricular note, you will have this depolarization and that's your um P wave uh then have this bit here from your ventricular note to your bundle of piss. This is kind of a bit of a delayed period whereby um the ATRIO ventricular node will kind of halt or slow down this potential of passing through. And that's to allow the atria to fully empty the blood into the ventricles. And then here we've got this. So this is your QR S. So your ventricular depolarization and this is just whenever the ventricular systole occur. So that will force blood out into the great vessel to your pulmonary trunk and your aorta. So sound node here to your A V node, to your IV bundle bundle of his and then to your Pinzi fibers along here. So the sinoatrial note then is can be considered and is the pacemaker. So it sets kind of the rhythm for the heart. Um It can be influenced by extrinsic nerves from either your parasympathetic or your sympathetic nervous system, uh touched on that last week. So we'll leave it there. Um But it's really found in the posterolateral wall of the sinus of the Vena cava. So as you can see here, your sino arial node is just here. So this is your sins of Vena Cava. It's more kind of closer to the kind of opening of the superior Vena Cava uh in your right eight gym. So in the right eight gym, you've got this sinoatrial node, it's a pacemaker. So it'll kick off the impulses and it's supplied by the sinoatrial nodal artery. And if you got a blockage there, that would obviously affect your sinoatrial node. So next is the ATRIO ventricular node and it propagates the action potential. So it allows it to pass from the atria down into the ventricles. And uh it is really a secondary pacemaker. And what is meant by that is that the atrial ventricular note is able to generate its own action potentials. However, this is slower than what is done by the sinoatrial node. So the sinoatrial node would be kind of sending these impulses an awful lot quicker. So uh the atrioventricular node is essentially dictated to by the sinoatrial node and it's between the atria and the ventricles. So it's a secondary pacemaker and it's found in the posteroinferior atrial interatrial septum. So postero inferior just means that back towards the back low down on the endo atrial septum. And it found specifically in this area called cox triangle and is supplied by the atrioventricular nodal artery. And this is also a branch of the right coronary artery. So if you've got problems to the right coronary um that can then cause problems in these um nodes. And this has just shown a slightly more simplified diagram. So as you can see here. So anyway, D no and the particular note are in the right gym essentially. So the atrioventricular bundle or it's also called the bundle of his. So this is after the atrioventricular node. So this passes through and if you can remember, it was just a small opening in the fibro skeleton of the heart and it passes down there and it has right and left bundle branches. So it'll go from the bundle of his or a ventricular bundle along here. So down kind of into the uh membranous aspect of the interventricular septum. So this membranous aspect, interventricular septum down into the muscular aspect of the interventricular septum. So you get your right bundle branch and your left bundle branch and these will then pass down along and then reflect back up along the kind of other aspects of the ventricular walls and will feed into these purkinje fibers. These purkinje fibers are essentially subendocardiac fibers. So they're located in the subendocardium and this allows for the contraction of the ventricular muscle uh with this diagram as well. Um while the sa node kind of generates action potential there, it also needs to spread across to the uh left atrium also because you want both atria contracting at the same time. So to allow for that, you have this interatrial bundle and this interatrial bundle is called Bachman's bundle. So you might hear that notice, as I mentioned as well. So this here you've got this inter atrial bundle allows to go from the right atrium to the left atrium and it's bins bundle and that's just slightly easier to appreciate there. So send a note across the left atrium uh back on his bundle. But considering, so we have our atri ventricular note here, we have our ATRIO ventricular bundle kind of this kind of blue green color. That's your bundle of hiss. So this is going through the kind of membranous portion of the uh enteral, well, arial septum enters the MEMS portion of the uh inter particular septum. And then we have our Perkins fibers uh coming off from the left and right bundle bounces which are in the muscular part of the interventricular septum. And this allows for a coordinated contraction kind of from the apex of the heart to the base. And this will occur just to allow the blood to be flowing out of the aorta and then the pulmonary trunk. So that's the end of the teaching aspect. But there's just a few more questions just to finish off and hopefully these polls will work. Um Yep. So I finish these last MC Qs here in the next minute or two. Mhm. So what cardiac structure generates the action potential to initiate the myocardial contraction, the moderator band bundle of his S node, pin fibers or the node and to accommodate doctor Calvert uh who has a phd. Um we'll be finishing up at seven. So don't worry. OK, good. So we'll close that pool soon. So anyway, drill node will generate the action potential and this is because it's a pacemaker. So what what structure of the hearts conduction pathway is responsible for delaying the electrical action potential by approximately 100 and 20 milliseconds during the cardiac cycle. So what it might not have been in the slides, it was Manson. So I will put the pool up now. So what structure will kind of delay um the action potential to either a to fully empty into the ventricles. So the clear is it will delay to allow the atria to empty into the ventricles? OK. And stop the pool for that one. So er for this one, it is the atrioventricular node. So it will slow things down slightly and this is just to allow atrial cyst to occur to allow the blood to go into the ventricles. And then with that slight delay, that will then mean that there's more blood into the ventricles and then they will contract doctors. OK. Last two questions. Um In what layer of the heart are the purkinje fibers of the intrinsic cardiac conduction system found? So that's the pull up. Give me a few seconds for that. Yeah. OK. So your pent fibers are fine uh and the subendocardial layer. So it'll kind of fit into there and all like for the contract in the myocardium. Last question, a fun one. What is the name of the Coronary sinus valve? So I know I asked uh talked about it a while ago but uh is it East Asian Mitral tricuspid or the patient? And this is the last question, give a few seconds, let them. So it's maybe not one you'd really need to know that much, but just interesting to know. So the power of deduction here. So try and rule out what you think isn't applicable and then go for what you think, maybe a good day. So grand. So we'll end there. Um So the name of the Coronary sinus valve, the ba uh EAC is for the inferior vena cava and then mitral aortic further it involves. So these are the references for everything that I got the information from and thank you very much for uh attending and coming on. I hope it was useful for you uh in some way, um The teaching series will hopefully continue on uh the next few sessions will be in cardiac physiology, which I don't think it will be happening next week because there might be a progress test on. Um But uh they'll start up the week after. Um But uh this is our social media for Instagram. Um So if you want to scan that, um you can get access to our kind of communications. So we'll be putting stuff out there on what's happening next in the teaching series. But uh thank you very much for taking the time and if possible, I would appreciate um, if you could um uh fill out a feedback form for us, which I'll maybe put up slightly later on. But uh thank you very much for taking the time and if you wanna head across, er, scrubs or having a first year survival uh are best practices for first year, er, which we taught by Doctor Glen Calvert phd. Um So I would definitely recommend that to be you.