hi let's talk about the pericardium in this video we'll discuss the pericardium
the pericardium is a sac that surrounds the heart which is comprised of
two membranes that fall really into three layers the outermost layer which we can see here is the
fibrous pericardium deep to the fibrous pericardium is a mesothelial membrane called the
serous pericardium which has a parietal layer and a visceral layer from what you understand about
mesothelial membranes you'll know that the parietal layer tends to adhere to the walls
and the visceral layer adheres to the viscera which we'll see the pericardium
as a as a unit is very helpful for navigating the mediastinum because its borders are what defines
the middle mediastinum anything anterior to it is the anterior mediastinum anything posterior
to it is the posterior mediastinum we can see that it is falling within that mediastinal space
so medial to the pluri and interestingly enough it's fused to the central tendon of the diaphragm
now the fibrous pericardium is a rough and tumble sac it's predominantly comprised of collagen and
so it's not elastic at all it allows for the heart to expand during diastole but it doesn't stretch
so here we can see the heart wall and the layers of the pericardium there
that outermost layer is the fibrous pericardium so it's a collagenous tri-layer with each layer
woven at about 120 degrees angle with respect to the other this provides a nice barrier between the
uh the heart and what's outside of the heart so it's a it's a physical barrier to prevent
diseases it's also a nice anchor for the the heart within the the mediastinal space
deep to this parietal uh deep to this fibrous pericardium is the parietal layer of the serous
pericardium also known as the parietal pericardium so this is a serosal membrane
this is simple squamous epithelium with the basement membrane below it the the parietal layer
the serous pericardium is innervated by branches of the phrenic nerves so for any pain it's
brought up through the roots of the phrenic nerve so c345 keeps the diaphragm alive
deep to this parietal pericardium is the pericardial cavity
and that pericardial cavity is surrounded
on the inside or the deep side by that visceral layer of the pericardium
the pericardial cavity isn't so much a a large patent space like one would presume
but we we discuss it that way for the purposes of understanding so
if we if we move over here we can uh we can relate the serous pericardium to a balloon that someone
is invaginating their fist inward so the the space within the balloon is maintained and then there is
a visceral layer to this space and a parietal layer to this space as well and the cavity is
the space between these two layers and as we can see here there's the parietal pericardium
that would adhere to the fibrous pericardium and there's the visceral pericardium that would adhere
to the heart itself and be known as the epicardium so this pericardial cavity typically has not
much in it generally about 15 to 20 mils of a fluid known as ultrafiltrate that's secreted by
the visceral layer that visceral layer even though it's mesothelium is ciliated uh mesothelium and so
there's there's a lot of secretion from that layer to produce the ultrafiltrate
that visceral layer becomes the de facto surface of the heart and so we call it the epicardium
deep to the epicardium will be sub-serosal adipose connective tissue and its thickness
tends to be proportional to an individual's cardiometabolic risk level so the more epicardial
fat that is present the greater the risk of coronary artery disease hypertension insulin
resistance and diabetes etc the visceral layer of the epicardium is innervated by a different
source than the parietal level it's under autonomic control so it's going to be subject
to the whimsy of the cardiac plexus which we'll discuss in a later video the pericardium itself
is supplied by pericardiacophrenic arteries these are branches of the internal thoracic artery which
also serves the diaphragm so pericardiacophrenic pericardium and phrenic diaphragm
so we've discussed the various layers of the pericardium fibrous and serous and we've discussed
the layers of the serous pericardium parietal and visceral or epicardium and the pericardial cavity
between them this is your summary slide thank you very much for your time