Blood supply to the heart – PART 2 – Anatomy Tutorial


…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.