hi let's talk about the pericardium in this video we'll discuss how the pericardium is organized its
layers and pericarditis now the pericardium is a multi-layered sac which surrounds the heart it has
two distinct layers to it the fibrous pericardium which is the outermost rough and tumble layer
and deep to the fibrous pericardium is the serous pericardium which is a serosal membrane that has
two components there is a parietal layer which is fused to the fibrous pericardium
and then there is a visceral layer which is fused to the heart directly such that it is
part of the heart wall now between the parietal and the visceral layer is the pericardial cavity
in total the pericardium is what defines
the middle mediastinum so anything anterior to the pericardium is the anterior mediastinum anything
posterior to the pericardium is the posterior mediastinum but wherever that pericardium is is
the middle mediastinum that middle mediastinum is found below the sternal angle plane which is
approximately there and it's also medial to the pluri which are lining the pulmonary cavities
inferiorly the pericardium is fused to the diaphragm and so you'll have movement of the
pericardium and the heart within as the diaphragm contracts and relaxes with respiration what's nice
about the pericardium is that it accommodates diastole or the relaxation of the heart
as blood is all pressure driven the heart through relaxation is able to move blood within it
so that fibrous pericardium is a collagen tri-layer collagen is a very durable
very inelastic protein and this tri layer is woven at right angles to itself so it's a very tough
inelastic layer that represents the the sum total of volume that the heart can hope to expand
into now deep to that fibrous pericardium is the serous pericardium
that sears pericardium you can um you can think of as a balloon
this is the uh the metaphor that that people like to uh to explain any uh serosal membrane has
so if you can imagine blowing up a balloon and then you know punching your fist into it such that
the balloon deforms around your fist now there's a part of the balloon that is immediately touching
your fist and that's going to be the serous i'm sorry the visceral layer of the serous pericardium
and then there's a part of the balloon that's not touching anything
and that's the parietal layer of the serous pericardium and the space between
which isn't very much is the pericardial cavity now that that serous pericardium has two distinct
sources of innervation the parietal layer
so that which is fused to the fibrous pericardium is innervated by branches of the
phrenic nerves the visceral layer that which is actually part of the heart and is superficial to
some adipose connective tissue fibroelastic tissue and then deep to that the myocardium
is going to be innervated by an autonomic plexus that innervates the heart so the cardiac plexus
so the space between parietal and visceral pericardium with no innervation is the
pericardial cavity and again this is not really so much a space as much as it is
a potential space with a modest amount of pericardial fluid which is extremely uh
an extremely powerful uh lubricant for within the heart
now the uh the pericardium itself is uh supplied by blood by the pericardiacophrenic
artery in veins these are proximal branches of the internal thoracic
artery in veins and so they're going to run down between the mediastinum and the in the pluri
the pericardium like any tissue is subject to injury or pathological process and if injured or
if diseased it can become inflamed and this is a condition known as pericarditis pericarditis
may be acute or it may be chronic acute is is much more common it's it's typically fewer than
six weeks and with this inflammation there can be an imbalance of the resorption of
pericardial fluid and so the the result of that can be what's known as a pericardial effusion
and there are different substances which can fill that that pericardium uh transudate exudate lymph
can blood can so that would be hemopericardium and if there is a significant volume of
effusion so fluid accumulation within the the pericardium that can lead to a condition known
as cardiac tamponade with cardiac tamponade the the increase of fluid within the pericardium
is going to exert pressure upon the heart such that the heart can't expand during diastole and
if the heart can't expand during diastole the movement of blood into the heart is going to be
compromised and so pericarditis that that leads to cardiac tamponade can be treated
by a procedure called pericardiocentesis with pericardiocentesis if you can imagine
so that would be the the xiphoid process that would be the the costal margins
on either side what happens is an individual takes a a hypodermic needle attached to a
syringe and they insert it between the xiphoid process and the costal margin from the inferior
to the superior now this is going to avoid the pluri it will go through the diaphragm
inferiorly and through the pericardium and one will be able to extract
whatever the source of that effusion is and allow the heart the opportunity to
participate in diastole as as it typically would while the underlying
disease process can be addressed or the the injury can resolve that leads us to the uh the assessment
question of this video and that is which layer of the pericardium is part of the heart wall
the correct answer here is the visceral layer of the serous pericardium that is called the
epicardium keeping in mind that the fibrous pericardium and the parietal layer of the
pericardium are fused together and then between the parietal layer
and the visceral layer of the serous pericardium we have the pericardial
cavity the serous pericardium is all of the above both parietal and
visceral pericardium but not fibrous pericardium so correct answer would be c visceral layer
of serous pericardium or the epicardium for short thank you very much for your time