this video is going to be about the heart I'm going to start with the external features and then we'll look inside each of the chambers of the heart that's the plan so this is the anterior or sternal costal surface of the heart this is the apex and the apex is pointing in fearly into the left and that apex is made up of the left ventricle how do we know that's the left ventricle well we can use these vessels right here to tell us that this is where the interventricular septum is the interventricular septum is the wall between the two ventricles and on the external surface there's a groove the interventricular groove and this is the anterior one and there are coronary branches of the coronary artery and there are veins in that sulcus so to the left is the left ventricle the sternal costal surface is formed primarily by the right ventricle so the right ventricle I know is to the right side of these vessels and then over here is the coronary sulcus that also has vessels in it so between this sulcus and this sulcus is the right ventricle so most of the sternal costal surface or anterior surface of the heart is formed by the right ventricle a little bit by the left ventricle and then by the right atrium we know this is the right atrium because here's the right here's the Oracle of the right atrium and we know that because also because here's the coronary sulcus or coronary groove between the right atrium and the right ventricle if we look at grant's atlas we can see the same things this is the apex of the heart pointing in fearly to the left left atrium excuse make that left ventricle right ventricle here's that anterior entrance interventricular groove or sulcus here's the coronary sulcus and the right atrium with its oracle we're gonna turn up so we're gonna look at the right atrium and a cut was made so we can look inside and first thing I see are these ridges these muscular ridges on the anterior wall of the right atrium those are called pectin eight muscles and they radiate from a muscular Ridge they radiate from a muscular Ridge called the crista terminalis and I think the way this was cut okay we might have to pause okay we're gonna look okay we're gonna look inside the right atrium now and the first thing I notice in the right atrium are these muscular ridges these muscular ridges are called the pectin eight mussels and pectin eight means comb-like and those muscular ridges radiate from a vertically oriented Ridge called the crista terminalis which is difficult to appreciate on this cadaver if we look inside the heart I can get the light right how about that if you look inside on the posterior wall you notice the posterior wall is smooth that's called the sinus Venera m-- and that's where the superior and inferior vena cava empty so my forceps entered the inferior vena cava and now my forceps are going through the superior vena cava so the post to your wall is smooth but it does have a feature that is an oval or round depression can you see that you could say yes or no okay good the that's called the fossa ovalis and that is a remnant of foramen that was present before birth called the foramen ovale so the foramen ovale was an opening between the right atrium and the left atrium so it allowed blood to flow from the right atrium to the left atrium and some adults you might see a little opening and I think it's more common superiorly then in fearly and this person looks like they have it and that would be a paitent fossa ovalis meeting it's open and that really from my understanding doesn't have a clinical significance just that little bit of opening you could also see the right atrial ventricular valve which is also called the cuspid valve sometimes it's not a tricuspid valve it just has two valves but typically it's a tricuspid valve or the right atrial ventricular valve so let's go into the right atrium I'm excuse me right ventricle and so the right right ventricle is open we see a relatively thin wall thin chamber wall on the interior surface of the walls they're muscular ridges those are called trabeculae karne and then emerging from the trabeculae kearney are these large cone like muscles and those are called papillary muscles so what I'm my probe is pointing to is anterior papillary muscle there are three sets of papillary muscles in the right ventricle anterior posterior and septal sometimes the septal ones aren't even don't even look like a muscle like right here where the chordae tendineae are just emerging from the interventricular septum extending from the papillary muscles are chordae tendineae you see these fibrous cords very strong and those are attached to the cusps of the valve so you can see them attaching to the cusps each cusps has corded chordae tendineae attached to it from two sets of papillary muscles the right ventricle has an additional specialization and it's this the moderator band or the septa marginal trabecula and this septum septa marginal trabecula extends from the interventricular septum to the anterior papillary muscle and it's carrying part of the conducting system of the heart so in the interventricular septum is the atrioventricular bundle and that bundle has a right side left side to it and the right side sends fibers on to the moderator band to the Purkinje plexus of the right ventricle so this is the moderator band and it's going from the interventricular septum to the anterior papillary muscle now here's the exit the way the blood exits notice how the blood from the right atrium almost travels horizontally to get into the right ventricle and then the blood leaves the right ventricle vertically and this is called the conus arteriosus the smooth area just checking yeah CONUS arteriosus or infundibulum and if we look down and I'll try to close the valve so this is the pulmonary valve don't know how great that's going to show up on camera I'm opening it's a it's 3 valve eul's make a semilunar valve that's the pulmonic valve that's the pulmonic valve let's look at that in a book so this is the right ventricle this is Grant's atlas here the papillary muscles chordae tendineae moderator band or septa marginal trabecula this is the conus arteriosus are infundibulum and then you can see the inferior surface of the cusps of the pulmonary valve and they're named by their position right and left and then anterior so the right and left are really positioned posterior but they're called right and left and then this is the anterior one so the deoxygenated blood that's leaving the right ventricle exits through the pulmonary valve goes to the pulmonary trunk and the valve eul's of the pulmonic valve fill with blood and they shut to prevent regurgitation so if we go back to the heart right atrium we went from the right atrium to the right ventricle and then the blood exited the right ventricle through the pulmonary trunk here pulmonary trunk goes to the right and left pulmonary artery's those go to the lungs and then the blood returns from the lungs oxygenated and enters the left atrium via these pulmonary veins the left atrium on this cadaver isn't open but the left atrium is very smooth walled it does have an article that here it is here's the left atriums article and that will have some pectin 8 muscles in it okay pause so this is the left atrium that we've been looking at and I said it wasn't open so I'm going to open it with some scissors okay the scissors turned upside down so you can see inside and see how smooth wall that is okay here's the article of the left atrium so I can probably stick my probe into it yep from that chamber so if we look down the atrium you should be able to see that bicuspid valve or the left atrial ventricular valve or the opening for it right here where my probe is sticking so the blood came into the left atrium by way of the pulmonary veins and then it's going to leave the left atrium go through the bicuspid valve into the left ventricle so let's go to the left ventricle and here it is this right here is a valve of the bicuspid valve so if I stick my probe up this way okay we're going to go back to the left atrium you can see the probe coming up through the valve the left atrial ventricular valve or the bicuspid valve or it also goes by mitral go back to the left ventricle so we see similar things to the right ventricle we see the trabeculae karne that a little more well-developed in the left ventricle we see the papillary muscles they're going to be two sets of papillary muscles in the left ventricle compared to the right ventricle that had three sets the number of sets of papillary muscles corresponds to the number of cusps for the valve and you can really see this cusps and the chordae tendineae attaching from the papillary muscle to the cusps of the valve I think this one's a really nice-sized popular excuse-me chordae tendineae the other feature of this ventricle is look how thick the wall is much thicker than the wall of the right ventricle and that's because of the pressure that the right ventricle has to push against is much greater than the pressure that the right ventricle has to push against so now the Bloods gonna leave the right ventricle and exit through the aortic valve and this cut cut right through the ACE ending aorta so okay so the Bloods gonna leave the left ventricle and exit through they or tick valve and then enter the ACE ending aorta the way this cut was made it was cut through the aorta so I'm going to close it back up and you can see they or two here the ACE ending aorta and I'm going to open it back up and then you can see so it's really helpful to see the valves so there are three semilunar valve eul's and just like the pulmonary valve the structure of they ordered valve in the structure of the pulmonary valve are similar and so the blood will exit and then it'll these sinuses will catch the blood and close the valve to prevent regurgitation I also want to put out a put out point out the openings for the coronary arteries so here's the left coronary artery and you can see the opening of the left coronary artery very near that sinus could you see that yes good and then over here on the right we can see the opening for the right coronary right there so the right and left coronary arteries are the first branches of the aorta they're coming off the ACE ending aorta so check out that relationship here's they ordered sinus for the aortic valve and then there's the opening for the right coronary so I know that was kind of a long video but it showed external features and internal features of the heart hope that was helpful