Transcription

This is a tutorial on the heart and some of the major vessels that lead to the heart and from the heart. Here, we’re looking at an anterior view of the chest with the thoracic cage and the muscles dissected away.   You can see the heart sitting centrally in the mediastinum, which is this central compartment of the chest separating the pleural cavities on either side. The heart, as you can see, is angled to the left.   The apex of the heart is angled down into the left. You can see it sitting on top of the diaphragm, which is this flat muscle here.

In the anatomical position, which we’re looking at now, the heart has several surfaces. The surface that’s in contact with the diaphragm, the inferior surface of the heart is known as the diaphragmatic surface. This right side of the heart which is in contact with the right lung is called the right pulmonary surface. Conversely, the left side which is in contact with the left lung is called the left pulmonary surface.

The anterior surface of the heart, which is in contact with the sternum is called the costosternal surface. The back of the heart, which you can’t see in this particular view is known as the base of the heart. This point here is the apex of the heart.

It’s important to note the orientation of the heart in this position.   When you’re looking at it from this view, front on, you’re seeing mostly the right side of the heart.   From this view, you’re seeing mainly the right ventricle.

Just to quickly go over the basic structure of the heart and the function of the heart, the heart can be thought of as a dual pump.   You’ve got a pump to the lungs and a pump to the body. Deoxygenated blood is received from the rest of the body into the right atrium. It is then pumped into the right ventricle, which then contracts to send blood out through the pulmonary trunk into the lungs where it receives oxygen.

Once oxygenated, the blood is returned to the heart via pulmonary veins into the left atrium. The left atrium contracts and sends blood into left ventricle, which then sends blood out via the aorta to the rest of the body. This blood is oxygenated because it’s been received from the lungs.

Just when you’re watching this tutorial, the blue-colored vessels are veins and the red-colored vessels are arteries.   The color of the vessel doesn’t actually relates to whether or not the blood is oxygenated in this model. The blood that is sent out of the right side of the heart to the lungs is deoxygenated, but on this model, you can see that the pulmonary arteries are actually red because they’re arteries. This is the only artery that carries deoxygenated blood in the body.

And also, you can see the pulmonary veins which are returning from the lungs into the left side of the heart, the left atrium are blue in this model because they’re veins. But again, these are the only veins in the body that carry oxygenated blood.   Just to point that out.

Between the atrium and the ventricles, you have valves, which prevent the backflow of blood.   Between the right atrium and the right ventricle, you’ve got a valve known as the tricuspid valve. I remember the tricuspid valve as being on the right because tricuspid contains the letters ri.   tri, ri, right if you know what I mean. If not, just try and remember that the tricuspid valve is on the right.

And on the left, between the left atrium and left ventricle, you’ve got the mitral valve.

You’ve also got valves between the vessels that lead away from the heart and the ventricles.   Between the pulmonary trunk and the right ventricle, you’ve got a valve called pulmonary valve. And between the aorta and the left ventricle, you’ve got the aortic valve.

These are four valves that you need to remember – the tricuspid one on the right between the right atrium and the right ventricle, the mitral valve between the left atrium and the left ventricle and you’ve got the pulmonary and aortic valves.

Don’t worry too much about what these look like and the structures of them because I will be doing a more detailed tutorial on the structure of the heart including blood supply to the heart, all the different bits of the hearts and I’ll be looking at the hearts in more detail.   In this tutorial, what I want you to remember is you’ve got the two atria which pump blood to the two ventricles and the ventricles pump blood through the major vessels. And between the atrium and ventricles, you’ve got the mitral and tricuspid valves and between the ventricles and these great vessels, you’ve got the pulmonary and aortic valves.

The great vessels are those vessels which take blood directly to the heart, and take blood directly from the heart.   You’ve got four great vessels, you've got the vena cava, you've got the pulmonary trunk, the aorta, and you've got the pulmonary veins.   Blood is brought to the heart by the vena cava, you've got the superior vena cava and the inferior vena cava.   You’ve got these veins which drain into the vena cava, called the brachiocephalic veins, so you've got one on each side.

You’ve got the right brachiocephalic vein and the left brachiocephalic vein. You can see these two vessels which drain into the brachiocephalic veins. You’ve got the external jugular vein and the internal jugular vein.   The external one is more lateral and the internal jugular vein is more medial.

This is quite easy to remember because often in anatomy, the word ‘internal’ is substituted for ‘medial’ and the word ‘external is substituted for ‘lateral’.   When people talk about medial rotation and lateral rotation, they also might call it external and internal rotation.   You’ve got internal jugular vein and the external jugular vein draining into the brachiocephalic vein.

The right and left brachiocephalic veins converge to form the superior vena cava, which rains into the right atrium.

The next great vessel is the pulmonary trunk. This splits into two vessels. You’ve got the left pulmonary artery and the right pulmonary artery. These are the arteries that go to the lungs carrying deoxygenated blood to the lungs.

Once oxygenated in the lungs, the blood vessels which carry the oxygenated blood back to the left atrium are the pulmonary veins.   You’ve got four pulmonary veins on either side of the left atrium.   They return oxygenated blood to the left side of the heart, the pulmonary veins.

Next, we’ve got the aorta. This is this vessel here which leads out to the left side of the heart, the left ventricle.   It arches the pulmonary arteries here and it’s got several branches – or three as you can see.

You’ve got this branch here, which is called the brachiocephalic trunk. This branch splits into two. Ignore that annotation. This is the right common carotid artery and you’ve got the subclavian artery.   The aorta which comes out of the left ventricle splits into three branches. The first branch here is the brachiocephalic trunk and this splits into two. You’ve got the right common carotid and the right subclavian which goes off to supply the right arm. And the common carotid here goes up to supply the head and the neck and it splits into two branches, the internal and external carotid artery.

The next vessel we’ve got here is the left common carotid artery.   Just like you’ve got the common carotid artery here – again, ignore that label because it’s incorrect. You’ve got the right common carotid here and the left common carotid which comes immediately off the aorta. That’s the middle branch.

The final branch, the most posterior branch is the left subclavian artery. Just like you’ve got the right subclavian artery here, you’ve got the left subclavian artery here. It is a little bit confusing because you’ve got one of the branches which is the left common carotid artery, but this branch is the brachiocephalic trunk which later separates into the right common carotid and the subclavian artery.

Just to go through that again, you’ve got the aorta, which comes out of the left side of the heart and you’ve got three branches, three arteries which come off the aorta. Most anteriorly, the first one, you’ve got the brachiocephalic trunk. Next, you’ve got the left common carotid artery. And most posteriorly, you’ve got the left subclavian artery.   The subclavian arteries arch off to supply the arm. The carotid arteries go up to the head to supply the head, neck and brain.

The brachiocephalic trunk splits into two. It splits off into this right subclavian and the right common carotid artery. Here, you’ve got the left common carotid and finally, you’ve got the left subclavian artery.

The common carotid arteries on either side split into external and internal carotid arteries.   The right common carotid artery splits into the right external carotid and the left external carotid. And as you can see here, they go up to supply the brain and the head and the neck.

Just quickly recapping what I’ve told you, you’ve got these veins which drain the head and neck. You’ve got the external jugular and the internal jugular. These drain into the brachiocephalic veins. You’ve got one on either side – left and right brachiocephalic veins, which drains into the superior vena cava.

The pulmonary trunk here, which comes out of the right side of the heart splits into left and right pulmonary arteries.

Blood received from the lungs and is oxygenated returns to the left side of the heart via the pulmonary veins and you’ve got four of these on either side – not on either side, four of these together, two on either side.

And then you’ve got the aorta, which has three branches leading off it. The first one is the brachiocephalic trunk, which splits into the right common carotid and right subclavian artery. The middle one, the middle artery is the left common carotid and the most posterior is the left subclavian artery, which goes off to supply the arms.   Those are some of the major vessels that you need to know which come off the heart and lead to the heart.