hi my name is dr. Katz's and this is a video be of the series of videos on the heart we will focus on the external anatomy of the heart the heart is made up of four major chambers and we refer to these chambers as the left and right atria singular atrium so if I label these this is your right atrium and this is your left atrium and then we have the much bigger chambers which are your right ventricle and your left ventricle now the atria are referring to the actual spaces inside of these rather flappy looking like structures in the brown and these flappy ears we tend to refer to as Oracle's literally meaning the ears of the atria notice too that separating the atria from the ventricles we see major blood vessels that feet the heart we'll talk about those later those coronary vessels but they sit in these grooves in between the atria and the ventricles and even in between the ventricles so these grooves we can refer to as sulky or singular sulcus this should ring a bell cause you saw that term in brain anatomy as well so just for example a groove in between an atrium and a ventricle we can call an atrial ventricular sulcus while a sulcus in between two ventricles we would call an interventionist we call that the term inter always means in between okay when we look at the heart anteriorly this is when we can really see how twisted the heart is and this is what I'm referring to at the top and bold what that is trying to tell you is that when you look at the heart anteriorly you actually see almost all of the Wrights chambers but you see only a small portion of the left chambers so the left chambers are twisted towards the back towards the posterior aspect of the heart and when we look at a posterior view you will see that now let's focus on the major arteries that first of all leave the heart and for this we'll start with the aorta and I'm going to pick a better color so that we don't get so confused with reds and blues and and all of that so let me switch to a dark green here so we see the aorta right here and our second major artery is what we call the pulmonary trunk you can see them labeled here as well a order and pulmonary trunk and we can give whoops I misspelled a order there let's fix that we can give more specific names to portions of the aorta as you can already see here this short section is referred to as the ascending aorta then we have the arch of the aorta and we could continue to draw the aorta and say that we have our descending aorta continuing down the thorax going down through the diaphragm into the abdomen and eventually even splitting into the lower limbs I'll just call them legs to make it easier to write where does the blood come from that enters into the aorta well that blood actually arises from the left ventricle from the left ventricle and gets ejected into the aorta the aorta gives rise to three major fingers as I often will refer to them and you will need to know these three major branches we have a short stubby branch called the brachiocephalic trunk you'll see many blood vessels are referred to as a trunk when they look like they form the trunk of a tree because this brachiocephalic trunk is very rapidly going to split into these two branches I will label these branches in just a moment so I just pointed out our brachiocephalic trunk as our first major finger then we have the left common carotid artery watch your spelling for carotid and finally the left subclavian artery if you look at the names of all these different arteries subclavian meaning going underneath the clavicle on its way to the arm by the way carotid might not be as explanatory to you but I know from I'm quite sure that all of you know that carotid arteries feed into the brain or into the head and then brachiocephalic literally tells you break your arm cephalic going to the head anytime vessels are specified as for instance in this case left you can automatically assume that there must be a right version of that particular vessel notice that the trait brachiocephalic trunk does not have right or left in its name and that means there isn't there aren't two versions of this trunk we only have the brachiocephalic trunk on the most right portion coming off of the aorta but what we do see is that this brachiocephalic trunk immediately splits into the right subclavian artery I'll abbreviate them here and the right common carotid artery so we have right more versions of these left arteries this clearly shows you that there's a bit of asymmetry in all of these blood vessels be sure you know all of these vessels I just pointed out so all of this blood that leaves the left ventricle gets pumped into the aorta and from the aorta the blood is pumped pretty much to every part of the body except the lungs so we have a whole separate artery that carries blood into our lungs and that artery is called the pulmonary trunk notice that this artery is colored blue we'll talk about definitions of arteries and veins in just a moment the pulmonary trunk carries its blood it carries its blood to our left lung ll4 left lung and to the right lung via as you can see a pulmonary loops I meant to use my cursor there via a pulmonary artery that goes to the left lung so therefore called the left pulmonary artery and then we also have here our right pulmonary artery gas exchange occurs in the lungs and the kind of gas exchange that occurs in the lungs is such that the lungs will supply the blood with oxygen and consequently we will see that the blood that Lee the lungs will be oxygen-rich that blood will return to the heart via pulmonary veins which we see entering here on the back side of the heart these pulmonary veins that I'm pointing to right now all of them will return their blood to the left atrium so despite the fact that it seems on this figure that the right pulmonary veins dump their blood in this atrium that's not the case they actually are sitting on the back of the heart here and they all enter into the left atrium from the left atrium this blood that is now oxygen-rich will make it to the left ventricle and of course as you know from the left ventricle the blood enters the aorta and the ER that carries that oxygen-rich blood to all the tissues that need it okay so we've learned about the two major arteries and I've also introduced you to some veins namely our pulmonary veins which carry oxygen-rich blood we have two other major veins to point out and these are veins that return blood to the heart inferiorly from the lower portion of the body meaning everything below to heart and securely from everything above the hearts we call them the inferior vena cava and the superior vena cava this is the blood that visited all of the body tissues the blood that the aorta pumped out visited all the tissues the tissues picked up the oxygen and then the oxygen poor blood returns to the heart via T inferior vena cava and via the superior vena cava and this blood which is oxygen poor will get dumped into the right eighth into the right atrium from there that blood from the right atrium is going to make it into the right ventricle and from the right ventricle the blood will then be pushed into the pulmonary trunk which will then take it again to the lungs where it can become supplied with fresh oxygen we will review the flow of blood substantially in another video but what we can do here is clarify some terminology first of all let's define atrium a chamber that is called atrium is always going to collect blood so I'm just going to write out collect so I run you do not run out of space for some of the other definitions on the other hand ventricles they eject blood so ventricles they eject blood keep that in mind if you keep these definitions in mind you will not get confused about where blood goes when arteries are always defined as blood vessels that carry blood away from the heart so they carry blood away from the heart while veins on the other hand return blood to the heart do not define arteries based on whether they are oxygen-rich or oxygen poor vessels let's take a look at why you should not do that our aorta is an artery and it's colored red because it has oxygen-rich blood but we give it the name or we say that the aorta is an artery because it carries blood away from the heart let's take a look now at the pulmonary trunk the pulmonary trunk carries its blood the right ventricle to the left lung and to the right lung I just made that a bit messy there but my point is notice that that the pulmonary trunk plus the pulmonary arteries are colored blue these vessels carry oxygen poor blood despite the fact that they're considered arteries and why are they considered arteries because they carry blood away from the heart here we see our pulmonary veins colored red they return their blood to the left atrium remember an atrium always collects blood and they're colored red because they're oxygen-rich they just they contain the blood that just left the lungs the lungs supplied the blood with fresh oxygen yet they're called veins veins always return blood to the heart more specifically to the atria arteries that leave the heart always receive blood from the ventricles your soup your inferior and superior vena cava are colored blue because they carry oxygen poor blood and they return blood to the heart which is why they are considered to be veins I should point out one more structure and that's this little white connective tissue right here that interconnects the aorta and the pulmonary trunk in once we're born this is just connective tissue that replaced something that was there as we were developing as a fetus at that time the structure allowed for blood to travel between the pulmonary trunk and the aorta and you will see why this is when you learn about fetal circulation we refer to this structure in a fully developed heart as the ligamentum arterial here now we're looking at the posterior side of the heart and remember if we're now looking at the posterior side that means that when we look at the right side of the heart it's really the right side if you follow me here so this is our right ventricle here is our left ventricle here is our right atrium and here is our left atrium right about here lots of coronary vessels once again we'll get to those later on but the point to make with this particular image is the following or the points are the following for one we see most of the left side of the heart in this view so the left side of the heart points mostly post early secondly you can now clearly see how all of the pulmonary veins that return oxygenated blood back to the heart do that by returning the blood to the left atrium right here and then finally we also see how the inferior and superior vena cava enter the right atrium we're now ready to review the coronary circulation of the heart which consists once again of arteries and veins we'll start with the anterior view and point out the location of the aorta which of course is this big structure right here from the base of the aorta from the base of the aorta we see two major arteries arising and these are referred to as the left coronary artery and the right coronary artery the left coronary and the right coronary artery the right coronary artery this is again an anterior view we'll right away start sneaking down that sulcus that separates the right atrium from the right ventricle that atria that right atrial ventricular sulcus to then wrap around to the back as it follows that sulcus our left coronary artery is also going to give rise to a branch that descends into this interventricular sulcus and we will refer to it as the anterior interventricular artery this one right here it's other branch will continue in the sulcus that separates our left atrium from our left ventricle and in that sulcus then we call the vessel the circumflex artery and it gets that name because it'll literally continue in that sulcus to the back it kind of bends around like circumflex to bend around we'll continue with the arteries the coronary arteries on the next slide but since we have this anterior view here on the screen I'm going to go ahead and add the major veins that you have to know in the sulcus in which the anterior interventricular artery sits we also see a major vein that drains the heart and we call that the great cardiac vein so in the interventricular sulcus we have our major anterior and interventricular artery and then our great cardiac vein in the sulcus that separates the right atrium from the right ventricle we have the small cardiac vein so now we're looking at the posterior side of the heart and so to not get confused let's label our major atria since this is an intervention or sulcus on the posterior side we can label this as the right ventricle let me use a different color there right ventricle the right atrium here the left atrium there and the left ventricle here so let's first focus on the arteries remember that we had that circumflex artery bending around the heart and here we see it it eventually descends here but I'm not going to hold you responsible for those smaller coronary vessels I'll mark the one that you have to know or ones that you have to know so you have to know that circumflex artery also remember we also learned on the anterior site that right coronary artery it also stays in that atrial ventricular sulcus to then give rise to a minor or smaller coronary artery here and another important one that I do need for you to know in that interventricular sulcus on the posterior side and so it is referred to as the posterior interventricular artery meaning it sits in between the ventricles on the posterior side so those are your coronary arteries let's finish now with the the veins I introduced you to the great cardiac vein on the posterior side and notice that it also takes advantage of that sulcus and then it merges with this very wide sac-like vein which we call the coronary sinus when we use a term sinus amongst blood vessel it implies a very thinly thin sac like type of a vessel it doesn't really look like it too much it looks kind of more like a sac this picture doesn't really show that but in real life it is that way so all of the blood that has been nourishing the heart and now has lost its oxygen has eventually returned to that coronary Zionists and that coronary sinus is going to return that oxygen-poor blood into the right atrium because from the right atrium then that oxygen poor blood will make it into the right ventricle and the right ventricle will push that oxygen poor blood into the pulmonary trunk where from where the blood will eventually make it to the lungs to get reoxygenate it so don't forget the blood from the coronary sinus via a small opening will actually drain into the right atrium somewhere around here there is one more cardiac vein to point out that takes its blood into the coronary sinus and that is this one right here which we call the middle cardiac vein on the anterior side we have two great cardiac vein that been around and appears here in that atrioventricular groove but in the interventricular groove on the posterior side something pretty much parallel to the posterior interventricular artery we find the middle cardiac vein okay so quick summary the heart muscle tissue itself must be supplied with oxygen-rich blood and that happens with the help of our left and right coronary arteries and their branches the left and the right coronary arteries arise from the aorta the oxygen poor blood that starts to accumulate needs to be drained and that is drained with the help of the coronary sinus which in turn dumps the blood into the right atrium and from there of course the blood can eventually be reoxygenate it's in the lungs so this wraps up our external anatomy