Coronary Vasculature

00:01 So we think about the heart being responsible for pumping blood throughout all of our arteries that it's easy to forget sometimes that it's a muscle that needs its own arteries.

00:11 So, that's why we're going to talk about the arteries supply the heart itself, the coronary arteries.

00:18 Last time, we mentioned there are these holes that exist right above the aortic valve called ostia.

00:25 We had one on the left called the left coronary ostium.

00:28 And it's going to feed coronary artery called the left main coronary artery.

00:34 Similar, we had an opening on the right called the right coronary ostium, that's going to feed into the right coronary artery.

00:42 And that other cusp, that's called the posterior one is also called the non coronary cusp because no coronary arteries originate from it.

00:52 So let's look at the right coronary artery and its branches.

00:56 So we have the right coronary ostium on the aorta, giving rise to the right coronary artery going down between the groove that exists between the right atrium and the right ventricle.

01:08 And it's giving off branches along the way.

01:11 And one such branch we see here is called the right or acute marginal artery.

01:17 And if we swing around to the posterior/inferior side, we see again, that right or acute marginal artery on the edge there.

01:26 And the right coronary artery continues along that groove between atrium and ventricle until it reaches that groove we talked about called the posterior interventricular sulcus that represents the groove in between the atria.

01:42 And there, it usually forms the posterior descending artery or PDA, also known as the posterior interventricular artery because of its location.

01:54 And it's going to go along that groove along the inferior portion of that septum all the way out to the apex.

02:01 Now, I say this is formed by the right coronary artery, because that's the usual orientation, about 80% of the time, that's what happens.

02:10 And if that is the case, we say a heart is right dominant.

02:14 But a heart can have its PDA supplied by the left coronary system, in which case it's called left dominant.

02:23 And on rare occasions, the PDA can be fed equally by the right and left in which case it's called codominant.

02:32 And on the other side, we have the left coronary artery and its branches.

02:37 But in order to see that, we're going to have to fade out the left atrial appendage to really see what's going on.

02:44 Here we have the left coronary ostium coming off of the aorta, giving rise to the left main coronary artery.

02:52 In the same sort of distribution that we saw for the right in that groove between atrium and ventricle, but it's going to be very short, only about a centimeter before it branches.

03:02 And one of those branches is going to be a very prominent one going down the anterior interventricular sulcus.

03:08 Hence, one of its names anterior interventricular artery was more commonly known as the left anterior descending artery, or the LAD, providing a lot of the blood supply to the left ventricle.

03:21 The other branch is going along that groove still, between the atrium and the ventricle, that branch is going to be called the circumflex artery, because it's going to head around to the posterior surface.

03:35 It's both of these arteries are going to give off some branches along the way.

03:38 Some of the important ones are the diagonal branch or branches that come off of the LAD as they cover the surface of the left ventricle.

03:47 And they're quite important clinically, because they're often involved by atherosclerosis.

03:52 And the left ventricle, well, that's the one that's pumping all the blood out to the body.

03:56 So it's a really important ventricle in that sense.

04:00 The circumflex is giving off an artery called the left or obtuse marginal artery, which you might imagine is sort of a mirror image of the right or acute marginal artery.

04:11 Now that we've covered the arterial supply of the heart itself.

04:15 We're going to have to deal with the veins that drain the heart itself.

04:18 And we call those the cardiac veins.

04:22 So if we again look at the right side, we see the right atrium and that groove between the right atrium and ventricle or that sulcus, and that's where the right coronary artery was traveling.

04:36 Right in that same area, we see some veins draining the right ventricle called anterior cardiac veins.

04:43 And these veins are a little different than the other ones we're going to talk about, because all the other ones head towards something called the coronary sinus.

04:51 But the anterior cardiac veins, they actually just take a shortcut and go straight into the right atrium themselves.

04:57 There's another vein down here that we see called the small cardiac vein.

05:02 And despite its name, it actually does a lot of drainage.

05:05 And it's more typical in the sense that it usually will drain into that structure we call the coronary sinus.

05:11 We swing around to the posterior surface.

05:15 We see our right atrium where all this venous blood is headed toward, and the inferior vena cava.

05:21 That's providing the deoxygenated blood from below.

05:25 And a little bit of that small cardiac vein we saw on the other side.

05:31 Now we see the largest vein, in fact, the largest vessel on the surface of the heart, which is the coronary sinus.

05:38 Training most of the veins.

05:40 Again, other than the anterior cardiac veins.

05:45 We see our coronary artery, the posterior descending artery running along the posterior interventricular groove.

05:53 And it's got a vein running right along with it called the middle cardiac vein, which is a pretty good name because it's in between the ventricles. So it's sort of in the middle.

06:03 So it's a descriptive name in that sense.

06:06 We also see another big vein here, that's descriptive, because it's the posterior vein of the left ventricle.

06:12 Tells you exactly where it is and what it's draining.

06:16 And then a little tiny bit of something called the Great cardiac vein.

06:20 Doesn't look like much here.

06:22 And so why would it be called great if it's just a tiny little thing? Well, we have to swing around to the other side to see the rest of it.

06:29 So if we look at it from the left side, where we have the left atrium, and there's our inferior vena cava, over on the right, we have our coronary sinus heading to that junction, where the right atrium is going to receive all of our venous blood.

06:45 And it's receiving this really big thing called the Great cardiac vein.

06:49 And that's why it's called Great.

06:52 It's quite a bit larger than the other ones.

06:53 And it makes sense because we're on the left side now.

06:56 And so the left ventricle is doing a lot more work.

06:58 It's a lot thicker than the right ventricle.

07:00 It's pumping out into the entire body as opposed to just out to the lungs.

07:05 So it's going to use more blood, it's going to need more venous drainage.

07:09 That's why the great cardiac vein is so great.