Transcription

Arterial Supply

This is a tutorial on the vascular supply to the heart. I’m first going to talk a bit about the arterial supply and then I’ll talk about the venous drainage of the heart.

Like the rest of the body, the heart needs oxygenated blood to function.  Blood that’s received from the lungs into the left side of the heart is pumped out of the aorta and the aorta has some branches which supply the heart.

Coronary Arteries

At the base of the aorta just after the aortic valves, you’ve got two branches which come off the right and left coronary arteries.  Here you can see the right branch coming from the base of the aorta and the left branch which is slightly hidden under the pulmonary trunk. You’ve got left coronary artery coming off the base of the aorta.

The right aortic sinus gives rise to the right coronary artery and the left aortic sinus gives rise to the left coronary artery.  You’ve got these two main branches coming from the base of the aorta, the right and left coronary arteries. They’ve got various branches which I’m now going to talk about.

Sulci

Also on the heart, you’ve got grooves. You’ve got grooves between the atrium and the ventricles and you’ve got grooves between the ventricles. Between the atrium and the ventricles, you’ve got a groove called the coronary sulcus.  In anatomy, in reference to any groove, you’ll hear the word ‘sulcus’.  In the brain, the grooves are called ‘sulci’ (plural) or ‘sulcus’ (singular) and on the heart, the same thing apply.  You’ve got grooves which are called sulci.

The coronary sulcus runs between the atrium and the ventricles and the coronary arteries run in this coronary sulcus. Between the ventricles, you’ve got an interventricular groove.  An interventricular sulcus. This groove separates the right and left ventricle and some major vessels run down this groove.

Right Coronary Artery

Just following the right coronary artery around its course, it winds around along the coronary sulcus to the back of the heart and it gives off two main branches. You can see this branch on the right margin of the heart coming off the right coronary artery. This is called the right marginal branch. That’s the first branch.

And as we follow the right coronary artery right to the back, you can see this groove running between the atrium and the ventricles separating the atrium from the ventricle, it runs right around the heart. And then you can see this branch here. This is the posterior interventricular sulcus. The one I showed you on the front is the anterior interventricular sulcus.

The artery that branches from the right coronary artery and runs down the posterior interventricular groove is the posterior interventricular artery, which is also known as the posterior descending artery.

You’ve got two branches of the right coronary artery, you’ve got the right marginal artery and you’ve got the posterior interventricular artery or the posterior descending artery.

This is the right coronary artery you can see here in the coronary sulcus.

Left Coronary Artery

The left coronary artery arises from the left aortic sinus at the base of the aorta. Looking directly at the heart, you can’t actually see this branch. It’s hidden underneath the pulmonary trunk.

Again, this artery has a few branches. The first branch which you can see running down the anterior interventricular sulcus is the anterior interventricular artery, otherwise known as the left anterior descending artery.  That’s the first branch of the left coronary artery. This thing here is the right atrial appendage. I’ll just remove that so we can have a good look at the arteries.

This is the left coronary artery giving off the anterior interventricular artery as its first branch. And then it winds around all the way to the back just like the right coronary artery. This branch which winds all the way around is known as the circumflex artery. This gives off a branch here.

Like we’ve got this artery coming from the right coronary artery lying on the right margin of the heart called the right marginal branch or artery, we’ve got the artery on the left margin. It’s the left marginal branch. This comes off the circumflex artery.

The circumflex artery winds all the way to the back to the base of the heart and extends down.

You can see in this model, the circumflex artery extends very far down. There is anatomical variation between people. Sometimes, the posterior interventricular artery which usually arises from the right coronary artery, it can arise at the circumflex artery of the left coronary artery. This is known as coronary dominance. Someone whose posterior interventricular artery arises from the circumflex artery, they’ll be left dominant, whereas if the posterior interventricular artery rises from the right coronary artery, then they’ll be called right dominant.

In the majority of people, the posterior interventricular artery arises in the right side. But in some patients, the posterior interventricular artery arises from the circumflex artery, in which case, they’re left dominant.

In the case of this model, you can see both arteries run in equal lengths.  This would be a case of co-dominance. There’s an equal supply from the right and the left coronary arteries to the posterior surface of the heart.

Recap

Just to quickly go over that again, you’ve got two arteries which branch off from the base of the aorta arising from the aortic sinuses.  You’ve got the right aortic sinus giving rise to the right coronary artery and the left aortic sinus giving rise to the left coronary artery.

The right coronary artery winds around along the coronary sulcus giving off two branches – the right marginal branch and the posterior interventricular artery, which runs down the posterior interventricular sulcus.

The right coronary artery supplies the right atrium and the right ventricle. It supplies both the sinoatrial node and the atrioventricular node in most people. But remember, there is a certain degree of anatomical variation.

The left coronary artery gives off a few branches. You’ve got this first branch which runs down the anterior interventricular sulcus and is known as the anterior interventricular artery also known as the anterior descending artery, the left anterior descending artery.

And then you’ve got this branch, the circumflex branch, which winds around all the way to the posterior surface of the heart. The circumflex artery gives rise to this artery, the left marginal branch, which sits on the left margin of the heart, hence the name.

And in some people, the circumflex artery actually gives rise to the posterior interventricular artery in which case, the person is known as left dominant.  A person’s coronary artery dominance is determined by which artery supplies the posterior interventricular artery. If it’s the left coronary artery as a branch of the circumflex, then they’re left dominant. If it’s the right coronary artery, then they’re right dominant.

That’s the arterial supply to the heart. Next, I’m going to be talking about the venous drainage of the heart.

Venous Drainage

Okay! So the venous drainage of the heart is by several cardiac veins which drain into the coronary sinus, which lies on the posterior aspect of the heart on the inferior surface (this diaphragmatic surface). You’ve got this coronary sinus which lies between the left atrium and the left ventricle. It lies in the coronary sulcus between the left atrium and ventricle. The coronary sinus drains blood back into the right side of the heart.  Just like all the other deoxygenated blood, it returns blood to the right atrium.

This is the coronary sinus here. It receives four tributaries. You’ve got the great cardiac vein, which runs the anterior interventricular sulcus and winds around to join the coronary sulcus at the back. That’s the great cardiac vein.  It runs down the anterior interventricular surface, winds around and drains into the coronary sinus.

You’ve got this vein which runs down the posterior interventricular sulcus and this is called the middle cardiac vein. This joins into the coronary sinus.

This one on the margin of the heart is the posterior cardiac vein. It meets the great cardiac vein to join into the coronary sinus.  We just rotate to get around, you can see it lies on the left margin of the heart and it drains into the coronary sinus.  This is the posterior cardiac vein.

And then on the right side of the heart, you’ve got this small cardiac vein. This thin, little vein here running in the coronary sulcus is called the small cardiac vein. That runs between the right atrium and the right ventricle.

And you’ve got this little branch which comes off the small cardiac vein. This is the right marginal vein. This drains into the small cardiac vein, which drains into the coronary sinus, which drains blood into the right atrium.

You’ve got the coronary sinus, which has four tributaries. You’ve got the great cardiac vein running in the anterior interventricular sulcus. You’ve got the posterior cardiac vein, which runs on the left margin of the heart, which joins the great cardiac vein and joins into the coronary sinus. And then you’ve got the middle cardiac vein, which runs right down the middle of the back of the heart, the diaphragmatic surface of the heart in the posterior interventricular sulcus. And you’ve got the small cardiac vein, which drains into the coronary sinus.  Four tributaries which drain to the coronary sinus.

And then you’ve got these other two veins, which you need to know, the right marginal vein, which drains into the small cardiac vein and you’ve got these veins here which are anterior veins. These drain the anterior portion of the right ventricle.

So that’s the venous drainage of the heart.