does not issue a coronary artery. So it?s
a non-coronary-related cusp. So that leads
us then to an understanding of the coronary
The heart, as you might imagine, has an intense
metabolic need for nutrients and for oxygen.
And there are two arteries that will help
supply the heart with arterial blood. At rest,
about 225 ml per minute of blood is being
delivered to the heart through the right coronary
artery and through the left coronary artery.
Again, coronary means ?crown? and these
arteries will form a crown around the heart
itself and then issue numerous branches.
If we take a look in this view, we can see
our right coronary artery travelling down
within the coronary sulcus or atrioventricular
sulcus. It will wrap around to the posterior
diaphragmatic area of the heart and still
will travel within the coronary sulcus. And
we can see some branches issuing from the
right coronary here in this view. And then
along the right margin of the heart we see
a marginal artery issuing from the right coronary.
The left coronary artery we see here it?s
going to issue from the aorta right above
the left coronary semilunar cusp. It?s travelling
posterior to the pulmonary trunk and underneath
the left auricle. So the left auricle bridges
over the left coronary artery. The left coronary
artery at first is a very short segment. And
then it?s going to issue its two branches.
The one that travels in the anterior interventricular
sulcus is referred to as the anterior interventricular
artery. And then the other one that we see
here is going around within the coronary sulcus
but it?s wrapping around the left side of
the heart travelling within the coronary sulcus.
And as it wraps around, it?s when it?s
called the circumflex artery.
If we take a look at the coronary arteries,
there is a dominance or dominant pattern that
can be determined. And if we take a look here,
we have our right coronary artery. And, if
we follow our right coronary within the coronary
sulcus and see it wrap around the right side
of the heart as we do here, we will see that
the right coronary artery will dive down into
and travel within the posterior interventricular
sulcus. When the right coronary artery gives
rise to the posterior interventricular artery
that travels in this posterior interventricular
sulcus, this is called a right dominant pattern.
The majority of individuals have a right dominant
system. The percentage will vary from one
study to another. So it might be 70%, 80%
or maybe a little bit higher than that in
Here we?re looking at the opposite dominant
pattern. And if we take a look at what?s
going on here, we will see our left coronary
artery. We see the anterior interventricular
artery travelling in the anterior interventricular
sulcus, which is normal. Another name for
our anterior interventricular artery is our
left anterior descending artery, or the acronym
LAD. And LAD is commonly used in the medical
The circumflex artery is issuing right at
this point. And if we follow it around the
left margin of the heart to the diaphragmatic
view ? posterior view, we see it also travelling
in the coronary sulcus. And if we follow it
distally, we see it dives down into the posterior
interventricular sulcus thereby continuing
as the posterior interventricular artery.
And when it?s the left, in this case the
circumflex that gives rise to the posterior
interventricular artery, you?ll want to
call this a left dominant pattern. This is
the second most frequent pattern that we?ll
see. However, it is usually somewhere around
15, 16 maybe 17% in frequency.
The last pattern that can be seen as a variant
is a balanced pattern. In a balanced pattern,
what happens is we end up with two posterior
interventricular arteries, one coming from
the right coronary artery and then, if we
can move this one over here more in line here
and running parallel to the one coming from
the right we have two more clearly defined,
discernible posterior interventricular arteries.
That is a balanced pattern. And out of the
three, this one is the least frequent pattern
that we?ll see.
Here we have a superior view of the coronary
arteries. Here?s the aorta cut in cross
section. Here is your right coronary cusp
or right cusp. And here you can see the ostium
leading into the right coronary artery. The
right coronary artery in a dominant pattern
is going to supply primarily the right side
of the heart: right ventricle, right atrium.
Also it will supply important structures at
the conduction pathway: the SA node. And we
can see the artery right here leading to the
SA node. And it?ll also issue posteriorly
here most commonly an artery to the atrioventricular node.
It also helps supply the interventricular septum.
Here is the left coronary artery. The ostium
is right here, right above the left coronary
cusp. And again very short. Here you can see
it continuing as the anterior interventricular
artery or the LAD. This is the one that?s
most frequently blocked leading to a myocardial
infarction. And it can lead to death. Hence
it?s also referred to as the widow maker.
And then here?s your circumflex wrapping
around as we see here.
Here?s your posterior interventricular artery.
And I?ll give you a moment to think about it.
Which coronary artery is giving rise to
the posterior interventricular artery?
And the answer is the right one coming around,
diving down into the posterior interventricular
sulcus. So this is a right dominant pattern.
The left in this case is supplying mainly
the left ventricle, left atrium, interventricular
Like any other organ that?s receiving a
blood supply, the heart also has to have structures
in place that will help drain the organ of
So we do have a system of veins to do that.
The main veins to keep in mind here as a learner
will be the great cardiac vein, the middle
cardiac vein and the anterior cardiac veins.
Here in this view ? the sternocostal anterior
view ? we can see the first vein and the
last bulleted veins. So travelling here in
the anterior interventricular sulcus with
the anterior ventricular artery or the LAD
is its accompanying vein. And blood is flowing
upwards here in this system. This is called
the great cardiac vein and it?s going to
dive into the coronary sulcus, wrap around
the left margin of the heart and empty into
a structure that we call the coronary sinus,
a co-acting system.
We can also see here ? on the right ventricular
side ? we see in this case three anterior
cardiac veins. They?re draining the right
ventricle primarily of venous blood and they
empty directly into the right atrium. So they?re
very small ostea
or openings here into the right atrium.
The next slide will help us to understand
some of the additional veins and also see
what we saw on the anterior view wrapping
around here to the posterior view. And so
what we?ll want to focus on here, for a reference,
is the great cardiac vein coming up and around
to empty into the coronary sinus.
The coronary sinus will receive most of the
venous blood flow being drained from the heart.
A separate opening, large opening into the
right atrium that we saw in an earlier slide
when we looked at the internal anatomy of
the right atrium. We also have here, accompanying
the posterior interventricular artery, we
have its vein. This is called the middle cardiac
vein. It drains blood also into the coronary
sinus and thence into the right atrium.
We also have some smaller veins that will
empty into the coronary sinus. So the coronary
sinus drains most of the heart of venous blood.
The anterior cardiac veins are going to drain
primarily the right ventricle. And the last
system of veins that we have we cannot see
in this view. They run deep within the muscle
tissue itself and drain into the cardiac chambers.
And these are the venae cordis minimae.