So now let's Look at the location of the
heart in our thoracic cavity or the mediastinum.
The heart is located slightly to the left
and in the cardiac notch between the lungs.
The heart is deep to the sternum
and superior to the diaphragm.
If we look from a superior view of the thoracic
cavity, we find that the heart sits in the pericardium
which is a serous membrane surrounding
the heart and in between the lungs.
The pericardium is a double-walled
sac that surrounds the heart.
It's made up of two layers.
First you have the superficial fibrous pericardium.
This layer is going to function to protect and
anchor the heart to the surrounding structures.
It also prevents the heart from overfilling.
Deep to the fibrous pericardium, we have the second
layer which is referred to as the serous pericardium.
This has two layers as well.
It has a parietal layer which lines the
internal surface of the fibrous pericardium
and then it has an internal visceral layer
which is also referred to as the epicardium
and is found on the
external surface of the heart.
These two layers, the parietal and
visceral layers of the serous pericardium
are going to have a cavity in between
them known as the pericardial cavity.
This cavity has a fluid in it that helps to
decrease friction since the heart is moving so much
and you know friction causes heat so
we need a way to decrease that friction
and that's done here between
the parietal and visceral layers.
So recall from the previous slides that the visceral
layer of the serous pericardium is called the epicardium.
The myocardium is going to
be just deep to this epicardium
and includes circular or spiral
bundles of contractile cardiac muscles.
Also, the internal portion of the heart
and the part that's going to form an anchor,
the heart valves, is known as the cardiac skeleton.
This is a criss-crossing interlacing layer of connective
tissue that's going to anchor our cardiac muscle fibers,
support the great vessels that as the aorta and
the pulmonary trunk as well as the semilunar valves
and it's going to limit the spread of the
action potentials to specific pass in the heart.
Deep to the myocardium, we have the
innermost layer which is known as the endocardium.
The endocardium is going to be continuous
with the endothelial lining of our blood vessels.
This layer is going to line the heart's chambers
as well as cover the cardiac skeleton of valves.