hi let's talk about the structure of the heart and let's begin with the layers of the heart wall
on the left here we can see the heart having most of the pericardium reflected away so what you're
seeing here is the fibrous pericardium with the parietal layer of the serous pericardium
reflected back and then the immediate surface of the heart is a layer called the
epicardium which is the visceral layer of the serous pericardium
deep to that epicardium we'll have epicardial fat as we can see throughout here we'll also
have some blood vessels i can see a couple taking a rather tortuous route deep to that epicardium
on the right here we can see a dissected heart with that epicardium removed and we can see some
of those vascular elements that would have cruised along deep to the epicardium but more importantly
we can see a very robust myocardium the myo muscle cardium is the muscular layer of the
heart this is what allows the heart to relax and probably more importantly contract or go through
you know periods of diastole and systole to really serve as a pump for the blood that endocardium
is then lined i'm sorry the myocardium is then lined by endocardium which covers the
internal surface of the heart including the the the cusps of the valves and we can see
some elaborations of that here so these are trabecular carni
meaty beams found within the ventricles here we can also see a papillary muscle this anterior
papillary muscle which is an extension of the myocardium but still covered by endocardium
and in this atrium here we can see these pectinate muscles
again that's myocardium but it's still covered by endocardium so let's look at the the structures
which are peculiar to the various chambers of the heart and let's start with the right
atrium because let's just pretend like we're blood returning back from systemic circulation
there is our superior vena cava there svc that's draining everything uh superior to the diaphragm
coming down this is our inferior vena cava ivc here's a little bit of that inferior vena cava
there that vessel is draining all of the tissues inferior to the diaphragm we can see this smooth
walled area this is all called the sinus veneer and it is separated by the pectinate muscle
here by this very lovely ridge of tissue that ridge of tissue is called the crista terminalis
and it's at the superior point of that ridge of tissue where the sa node is going to live
let's take a different look at that right atrium this is more of a right surface look
you can still see the superior vena cava here's the inferior vena cava
and here is a very nice interatrial septum
and right about there is the fossa
ovalis a remnant of the foramen ovale so in utero there's two septa
a primary and a secondary septum which are parted and there is a space between them called the
foramen ovale the oval window through which oxygen rich blood coming from the placenta can pass
from the right atrium to the left atrium so that it may bypass the pulmonary circuit of circulation
we can also see a little flap here this has kind of been reflected away ever so slightly and
just beyond that is the opening for the coronary sinus or the coronary sign is us
as we go a little superior to that along this ridge would be the region where the av
node will live so that's the atria ventricular node kind of where the interatrial septum
meets the atrioventricular septum the right atrial serves as a pass-through conduit for
blood into the right ventricle here is the opening for the right ventricle or for the tricuspid valve
tricuspid valve has three cusps it has an anterior cusp it has a posterior cusp and it has a
septal cusp that septal cusp is largely immobile so in function the tricuspid valve works more
as a bicuspid valve we can even see some of the chordae tendineae of the right ventricle
let's get a better look at it there so here is that tricuspid valve
and here are those cordy tendony coming down to the anterior papillary muscle
there are three cusps and three papillary muscles um there isn't any fidelity between the two
so all of the cordy tendineae from the anterior cusps don't go to the anterior papillary muscle
that anterior papillary muscle is the largest of the papillary muscles and it is associated
with this beauty which has been incised which is called the septomarginal trabecula
the septomarginal trabecula or the moderator band would cut across from the interventricular septum
and allow the preponderance of the right bundle branch to cut across to the anterior papillary
muscle and the walls of the right ventricle we can also kind of see some of the cordy tendiny
maybe some in there as well but we'll get a better view of those when we get to the
the left ventricle and this region here is known as the conus arteriosus or the infundibulum
it's the smooth area
that is leading blood up to the pulmonary valve which is proximal to the pulmonary trunk
so here is our lovely view of the heart valves here is our pulmonary trunk here is our
ascending aorta then we have our tricuspid and our bicast bed so this would be the pulmonary valve
and the aortic valve so pulmonary valve is the anterior most vessel that we can see
looking at the left ventricle the best view is going to be from the posterior so this
is the base of the heart which has been incised and we can see some very lovely
pulmonary veins there these are delivering oxygen-rich blood back to the heart from the
lungs here we can see a little bit of that left article and within it some of the pectinate muscle
and the fossa ovalis is going to be obscured here by this portion of the
base of the heart my apologies for that
here's a better view with that reflected away and we can see the fossa ovalis located there
so blood is going to flow through the left atrium through the bicuspid valve
which has anterior and posterior cusps also called the mitral valve this is what is
blood is passing through between the left atrium and the left ventricle and it's what closes to
maintain the forward movement of blood from the left ventricle out the ascending aorta and aortic
valve so here's a view of the left ventricle this is a rather bizarre view of the heart so let's see
what we can see here to identify things here's the pulmonary trunk there is the ascending aorta
here's the superior vena cava there is a pulmonary vein there here is that interventricular septum
here's an anterior papillary muscle we can see lots of cordy tendony going to that muscle here
is the posterior papillary muscle also with lots of cordy tendineae and we have a very lovely view
there and there of the trabeculae carne the meaty beams that robust myocardium of the left ventricle
blood from the left ventricle is destined for systemic circulation and so it is going to
leave the aortic valve which has a right cusp a left cusp and a posterior
also known as a non-coronary cusp and these cusps are going to close during diastole
because pressure in the aorta is going to be greater than pressure in the left ventricle and
when that happens blood is going to then flow into these coronary arteries there's the right
coronary artery and there is the left coronary artery so we've discussed the various structures
of the heart as well as the structure of the heart and we've gone chamber by chamber
discussing the features which are peculiar to each chamber and the vessels and valves
that are associated with each chamber thank you very much for your time