hi let's talk about the superficial features of the heart in this video we'll discuss the
superficial features of the heart and how they relate to deeper structures
in terms of the heart basic structure is that there are four chambers
superiorly there are two atria that receive blood and inferiorly there are two ventricles
which distribute blood between the atria and the ventricles are the atrioventricular valves
there is a tricuspid valve on the right side and a bicuspid or mitral valve on the left side and then
there are semilunar valves named for the vessels that they drain into coming out of the ventricles
so there is an aortic valve leading from the left ventricle into the ascending aorta
and not pictured here but there is a pulmonary valve leading from the right ventricle into the
pulmonary trunk we can also see that separating the ventricles is an interventricular septum
and we cannot see but i assure you it is there between the atria and interatrial septum
now there are several heart surfaces that are germane to understanding the complexity of the
structure of the heart and i've color coded them for you in both a cadaveric photo as well as
some medical illustrations here and let's look at these so the portion of the heart which would be
immediately posterior to the sternum is the anterior surface
often referred to as the sternocostal surface that anterior surface is going to
be flanked on the right side by the right surface and on the left side by the left
surface often times called the pulmonary surface because it is in contact with the left lung
or the pluri surrounding the left lung but make no mistake the the right surface is also in contact
with the pluri surrounding the right lung there's also a diaphragmatic surface and that's difficult
to see from a profile picture here but if we look at the posterior view of the heart which is here
we can see that that diaphragmatic surface is rather extensive and that is the surface
which would correspond to laying above the pericardium which is fused to the diaphragm now
posteriorly we have the base of the heart the base of the heart is a rather trapezoidal shaped region
that is largely the left atrium we can see the association of the pulmonary veins they're
delivering blood back from the lungs to the heart there um and so that is the the base of the heart
there's also an apex of the heart which we will discuss and that apex of the heart is pointed
inferiorly and left laterally it's also probably worth mentioning that if we were to draw a midline
that roughly two-thirds of the mass of the heart will be found left
of that midline whereas one-third will be found to the right of that midline
there are also heart borders um and these borders i've i've color coded for you so this
would be in association with the right side of the heart we have the right border of the heart
and that right border of the heart is going to correspond deep to the
right atrium there's also an inferior border of the heart the inferior board of the heart here
is green so that would correspond roughly to where the diaphragmatic surface is
that inferior border of the heart is largely going to be the right ventricle but it will also include
a portion of the left ventricle as well and where that inferior border of the heart meets
the left border of the heart here's the left board of the heart that's the apex of the heart
that left border of the heart is largely going to be left ventricle but there's also going to be
part of the left atrium in association there as well and then there's a superior border of the
heart that's superior border of the heart is in association with both the right and the left atria
now these borders are useful um in particular when discussing radiography so i i have a couple
of chest x-rays for you to see here and um we can see the outline of the pericardium
it that contains you know some of the great vessels and the heart within and we can see
that between these two radiographs there's there's a very uh different amount of volume
that is um taken up by the pericardium for the radiograph on the right so if i'm
just to outline here pericardium we can see that the the width of the pericardium here
is probably much less than half of the total width of the thorax
and so this is a favorable what they call a cardio thoracic ratio whereas on the right here
maybe this is an exacerbation on the right here we can see that uh the the pericardium
uh takes up more than 50 percent of the the total space or or distance uh between uh
the uh the ribcage so this cardiothoracic uh ratio is much greater than than 50 and this is
an example of a condition known as cardiomegaly and that would be an enlargement of the heart now
size as a proxy for heart health um has its utility but it's not 100 so for instance
a very finely tuned uh athlete might have uh hypertrophied heart uh or a very you know strong
thick heart muscle because of training whereas you know an individual with copd might have
a cardiomegaly hypertrophied heart because their heart has to work extra hard to uh to
pump blood to the lungs to to overcome any oxygen deficit that that they have so um there are there
are different conditions that can lead to a hypertrophy heart so that's why i say approach
you know size as as as a proxy for health with uh with some modicum of of delicateness
now the uh the surface of the heart has various grooves within it and we call these grooves sulci
or sulci uh sulci um are going to be important for the transmission of various coronary arteries
and their branches cardiac veins and their branches so here running between the right atrium
and the right ventricle we can see a part of the coronary sulcus there we can see between the left
atrium and the left ventricle another part of the coronary sulcus there so this coronary sulcus
is going to be in line with the fibrous skeleton of the heart so the atrioventricular valves the
semilunar valves so they're going to divide you know atria from ventricles according to those av
valves so anything superior to the coronary sulcus will be atrium anything inferior will be ventricle
we also have interventricular sulci and so here is an example of the anterior interventricular
sulcus and we can see that both in the coronary sulcus and the anterior interventricular sulcus we
have coronary arteries in their branches cardiac veins and their tributaries etc we can also see
atrial appendages and these are called the oracles of the atria oracle means ear and
so these represent space into which blood can can flow during diastole as the the heart relaxes now
as we look at the posterior aspect of the heart we can see you know this is the coronary sinus
within the coronary sulcus we can also see there's a part of the coronary sulcus again and then here
containing the ant the posterior interventricular branch as well as the middle cardiac vein we have
the posterior interventricular sulcus also with a healthy amount of adipose tissue there and these
interventricular sulci both posterior and we can't see it but i'll kind of ghost it in there
anterior can be a proxy for the interventricular septum and so
the the branches of the coronary arteries so those anterior and posterior interventricular branches
are going to ride through the sulci and then send septal branches deep into the
interventricular septum to supply that myocardium with blood and that leads us to the assessment
question of the video which is the coronary sulcus serves as a conduit for heart vasculature
and corresponds to which deeper structures the cordy tendony the fibroskeleton of the heart
the interatrial septum the interventricular septum or the papillary muscles the correct answer here
is b the fibrous skeleton of the heart in particular to the atrioventricular valves
which comprise the bulk of the fibrous skeleton of the heart thank you very much for your time