...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. So 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.
So 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. So 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.
So 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.
So 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.
So 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, so 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. So 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.
So that's the arterial supply to the heart. Next, I'm going to be talking about the venous
drainage of the heart.
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. So
just like all the other deoxygenated blood, it returns blood to the right atrium.
So 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. So 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. So 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. So 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.
So 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. So 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.