...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.