External Anatomy of the Heart

00:01 So now let's look at the heart in some more finer detail, starting with the external surface.

00:08 And the important thing to always keep in mind when we're talking about where we can see things externally, is that the apex of the heart points down into the left.

00:18 So, that when we're looking at a heart, from a typical anterior point of view, most of that anterior surface is going to be the right heart.

00:26 It's going to be mostly right atrium and ventricle.

00:29 You're not really going to see a lot of the left heart.

00:31 It's going to be kind of hidden from view.

00:35 And if we look from a diaphragmatic surface, on the other hand, we can usually see both left and right pretty well.

00:44 It's also why on the right side, when we're looking at an interior point of view, we have the sort of right pulmonary surface forced up against the right atrium.

00:56 Again, because it's twisted a little bit.

00:59 And on the left pulmonary surface, we have more of the left ventricle, in addition to the left atrium pushed up against the left lung.

01:09 And again, the term base really is broadly meaning the broad part of an organ. But it's more specific in this sense that it's where all of the great vessels are going to attach to the heart as well.

01:25 So let's look at the borders of the heart from aninterior point of view as if you were just looking at someone's straight ahead in front of you.

01:34 Most of the right border is actually going to be the right atrium.

01:39 And the left border is going to have just a little tiny bit of left ventricle and the atrium.

01:46 Inferiorly because the apex again is pointing the way it does, we're going to have mostly right ventricle.

01:53 And again, superiorly, we're really talking about the base of the heart where both atria are also going to be located more superior and posterior to their corresponding ventricles.

02:07 Sitting on the surface of the heart are some grooves or sulci that are important landmarks, either because of things that run in them, or because of what they tell you is happening deeper into the heart.

02:19 The first one we have is this anterior interventricular sulcus and a corresponding posterior interventricular sulcus.

02:28 And it's really descriptive.

02:30 It's telling you which side we are anterior posterior, and it's telling you that this groove or sulcus is where the septum between the ventricles, the inner ventricular or simply ventricular septum is going to be found.

02:43 And when we talk about coronary arteries, for example.

02:45 We're going to see that these grooves have some important coronary arteries.

02:51 And we can also see another groove just to the left of where the IVC is going to enter, and that's called the coronary sulcus.

03:00 And that's going to be where an important cardiac vein.

03:02 The largest one called the coronary sinus is going to sit.

03:08 If we go back to an anterior view, we'll start to identify the actual parts of the heart and the things that connect to them.

03:16 So we have the inferior vena cava, inferiorly and the superior vena cava superiorly.

03:22 Both feeding into the right atrium.

03:25 And this little projection that projects a little bit anteriorly is the appendage of the right atrium or the right atrial appendage.

03:35 And the right atrium is going to feed into of course the right ventricle.

03:40 We can see a little bit of the pulmonary trunk that's being fed by the right ventricle.

03:45 However, it's twisting sort of behind and out of our point of view here, so we're going to have to see the rest of it in a different view.

03:53 We can see a good deal of the aorta here.

03:57 If we switch around to the left view though, we can see a lot more structures of the left.

04:03 Of course, we have the left atrium being more posterior and superior.

04:07 It also has an appendage, the left atrial appendage.

04:11 Although it tends to be smaller and narrower and longer than the right atrial appendage.

04:18 And these will feed into the left ventricle.

04:22 We don't see the origin of the aorta, and that's because the aorta sort of arches over from the right over to the left.

04:29 But we can see much of the arch as it's becoming the descending aorta here.

04:35 If we swing around to a posterior view, this is our best vantage point for the left atrium, And its corresponding feeder vessels, the left and right pulmonary veins.

04:49 And this is why a certain form of echocardiography called a transesophageal echocardiography or a probe goes down the esophagus can be really helpful.

05:00 If you really need to see the pulmonary veins in the left atrium, you use this anatomic relationship of the atria being very posterior right in front of the esophagus to your advantage to view it better.

05:13 We also see the posterior aspect of the pulmonary trunk and we see that it's very short before it branches into the left and right pulmonary arteries.

05:24 We really don't see much of the origin of the aorta, but we do see the arch coming towards us posteriorly, as it's about to descend.

05:33 Finally, on the right side, we can see the superior vena cava and inferior vena cava going into the right atrium, which isn't very easily seen in this point of view.