7B · Virtual Reality Lab: Heart Chambers

This is a walkthrough in the virtual reality anatomy lab, with no slides. Learning heart structures from two-dimensional illustrations in the textbook and lecture videos is one thing. Seeing a physical heart, with all its anatomical variability and quirky placement of features, is a whole other thing. This heart does look a little like the ones in the images and slides, but the three-dimensional human heart differs in other ways, with some structures placed differently from where we might anticipate.

This video is a quick overview of the chambers in an actual 3D human heart. The model is an MRI scan of a 97-year-old human heart, and it is in fantastic condition.

From the outside¶

The front view shows the right atrium, right ventricle, left atrium, and left ventricle. To get a good view of each chamber, the heart is twisted to give the best angle for what we want to see.

Right atrium¶

Opening into the right atrium, the walls carry ridges called pectinate muscles. These are simply ridges made out of the cardiac muscle in the right atrial wall. Most people think they are a way to increase the muscular content of the atrium without appreciably thickening the wall or making it much heavier.

Viewed from the top, the right atrium shows where the vena cava vessels enter: the superior vena cava, and on the back, where the inferior vena cava empties in. Moving down to the bottom of the chamber leads out of the right atrium and into the right ventricle. The valve between the chambers is the tricuspid valve.

Right ventricle¶

Cutting in from the front, through the muscular wall, shows the right atrium above and the right ventricle below, with the path where blood flows into the right ventricle and the path where it flows out. Blood comes in from the top and is also ejected out the top.

Inside are the papillary muscles. The right ventricle has three groups of papillary muscles, all visible here. They are outcroppings of the ventricular myocardium, attached to the chordae, which attach to the valve. The next video covers that connection in more detail.

Left atrium¶

The right atrium sat exactly where we expect it to be. The left atrium does not. It has to sit behind the aorta and the pulmonary trunk, and it is most easily seen from a side view.

Cutting in from the side, the whole hollow area at the back is the left atrium. It technically coalesces on the left side of the heart, but it tends to run behind the heart, especially in this particular heart. Moving through it, the chamber gets narrower and narrower, and vessels come in from the lungs, bringing oxygenated blood. Then the chamber gets larger again into the full-fledged left atrium, with more vessels bringing blood in from the lungs. The next video covers those vessels.

Left ventricle¶

With the left atrium located, the left ventricle sits just below it. Cutting into the front of the ventricle reveals the hollow left ventricle. The mitral valve lets blood move down from the left atrium into the left ventricle, and the outflow tract lets blood out through the aortic valve. Blood comes into the left ventricle from above, from the left atrium, and leaves through the top as well, out through the aortic valve and into the aorta.

Because the mitral valve has two flaps, the left ventricle has two big groups of papillary muscles, outcroppings from the left ventricular wall. The posterior group heads up with chordae to the posterior flap. The anterior papillary muscles send chordae up to the anterior flap.

Coming in from the side, tilted slightly, gives a view of the relationship between left atrium and left ventricle different from what textbooks offer: the left atrium, the left ventricle, the mitral valve between them, and the path where blood ejects from the left ventricle through the aortic valve and into the aorta.