The Anatomy Of The Heart
In this video, I go into the detailed anatomy of the human heart, from the four chambers to the valves to the major arteries and veins, the interatrial and interventricular septa to the lesser known chordae tendinae and papillary muscles. Enjoy!
So, let’s get right into it.
I’m looking at a picture of the human heart right now. In this human heart, of course, we’ve cut it open so that, you can see the internal anatomy and we’re going to divide this into the right and left side. So, this side here is the right side of the heart and this side over here, that’s your left side of the heart.
It might seem a little strange because you’re looking at it and it seems like this side is left to you and this side is right but, if this heart is in an individual and the individual is facing you then, this is the right side and this is left side. So, that’s how I want you to picture it.
The Chambers of the Heart
Now, first thing I want to look at are the chambers of the heart. We have four chambers and those four chambers will be our right atrium, which is this first chamber here on the right side, and then, we have our right ventricle. We have our left atrium and our left ventricle.
These are the four chambers, the four rooms and these are the rooms where the blood is going to be flowing through inside the heart.
Now, between the chambers and also leaving from some of the chambers, we’re going to have valves. These are things that can open and close to allow blood to flow. Let’s talk about those valves.
The Heart Valves
The first two valves that I want to talk about are the atrioventricular valves. The naming of those valves tells you exactly where they are. They are between the atria and the ventricles. So, on the right side, we’re going to have our right atrioventricular valve which is also called your tricuspid valve, and the reason why it’s called tricuspid valve is because when we look at the flaps of the valve, we actually have three of those flaps, or we call them three cusps. That is the tricuspid valve or the right atrioventricular valve.
Then, on the left side, we have our left atrioventricular valve. This one has more names. We have left atrioventricular valve. We have bicuspid valve. You should probably know what that means. It has those two flaps instead of three. That’s a bicuspid valve or the mitral valve.
Those are the three names for these valve on the left between the left atrium and the left ventricle.
Now, when we leave these ventricles, we’re going into different structures. So, we’re going to have some other valves that we need to know about. Those valves are, on the left side, we have the aortic valve and that is what is between the left ventricle and the aorta which is this large vessel that’s leaving from the left side of the heart from the left ventricle.
Right in between those two structures, we have this aortic valve. And then, on the right side leaving from the right ventricle, we have our pulmonary valve and that should tell you where the blood is going, right? It’s going to the lungs.
I should mention really quick that this is your pulmonary trunk and we’re going to talk about that in a little bit. But, these valves are also considered semilunar valves so, when you hear someone refer to the semilunar valves, you know they are referring to either the pulmonary valve on the right side going to the lungs, and we have our aortic valve on the left side, going to or leading to the aorta.
So, these are four valves.
Now, let’s talk about getting into and out of the heart. How do we do that?
The Major Blood Vessels in the Heart
Well, we have a number of vessels. The first vessel I want you to know about is the vena cava. We have the superior and the inferior vena cava. These are coming back to the heart. We have blood that’s coming from the rest of the body, and it’s coming back to the heart via these superior vena cava.
Then, we have the pulmonary trunk. We just mentioned that briefly. The pulmonary trunk, we’ve gone through our pulmonary valves and now, we are in our pulmonary trunk and this trunk actually divides into our left and right pulmonary arteries. You know where those are going. They are going to the lungs. So, that’s our pulmonary arteries.
Then, we have our pulmonary veins. You can see we have them on the left side over here and we have them on the right side over here. These are our pulmonary veins and these are coming back to the left atrium.
All right, so those are our vessels coming into and out of the heart.
Now, we need to talk about a few other things. Number one, we have our septa. We have the interventricular septum. That word septum,”all it means is a wall. We have a wall in between the left and the right ventricle so, we call that our interventricular septum.
We also have a wall between the left and right atria but, you can’t see that here because it’s kind of behind these other vessels but, just know that you have just like you have this wall between the left and right ventricle, you have a wall between the left and right atria and that is appropriately named the interatrial septum.
Now, when most people talk about the anatomy of the heart, that’s where they stop. But, I want to give you a little bit more information that you might not get in your Anatomy class. You might be able to impress your teacher with this one.
A Deeper Look into the Heart
That is looking at this structure. Now, you can see we’re seeing a little more detail inside the ventricles than we normally see, more than we were seeing in the previous image. This is often left out of many pictures of the internal anatomy of the human heart.
The structures that you’re seeing here, number one, are your chordae tendinae. These are like chordlike tendons, hence the name chordae tendinae. It’s connective tissue structure and you can see here that they are connecting the valves, so this is my right atrioventricular valve and it’s connecting those valves to a structure that’s lower down here. This structure that we’re looking at here, these structures are our papillary muscles.
What happens is when we look at the walls of the ventricle, we see that there are projections, little muscular projections and then, we have a bunch of these chords that are attaching the valves to those projections.
If you think about what’s happening in the heart, when the ventricles contract, we have our valves, so this is our atrioventricular valve and let’s say we’re looking at the one on the right side. When the ventricles contract, what’s going to happen is those valves are going to close because you’re applying pressure to those valves when the ventricles contract and you want those valves to close, they’re closing between the atria and the ventricles, so that the blood can flow in one direction and that in this case, on the right side is into the pulmonary arteries.
Now, if we didn’t have this chordae tendinae that are anchoring those valves to the papillary muscles of the walls of the ventricles, what would happen is when it contracts, it would go like this… And, that’s not good because what’s going to happen?
The blood is going to go into my atrium and we don’t want it to flow back. So, we have the chordae tendinae attached to the valves so that, when the ventricles contract, it’s going to close but, you’re not going to get any back flow.
That’s pretty much it. That’s my advanced tidbit. I hope you got some value from that.
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That’s pretty much it for this video. Until next time, I’ll see you in the next video.