[Plate 209, Pericardial Sac]The pericardium is a double-layered sac that encloses the heart and the roots of the great vessels.
The fibrous outer layer of the pericardium (the fibrous pericardium) consists of dense connective tissue.
The fibrous pericardium is attached to the central tendon of the diaphragm by the pericardiacophrenic ligament.
It blends with the tunica adventitia of the vessels entering and leaving the heart.
It has ligamentous attachments to the sternum
It is thus affected by movements of the heart, the great vessels, the sternum, and the diaphragm.
It protects the heart against overfilling because it is fibrous and unyielding
The inner layer of the pericardium is a serous membrane that lines the fibrous pericardium: the serous pericardium, also called the parietal
pericardium.
The serous pericardium is a mesothelial layer that reflects onto the roots of the great vessels and is continuous over the external surface of
the heart, where it is called the epicardium or visceral pericardium.
Between the serous pericardium (parietal pericardium) and the epicardium (visceral pericardium) is a potential space: the pericardial cavity.
The pericardial cavity normally contains a thin film of fluid that allows the two layers to move over each other without friction or rubbing.
There are two sinuses within the pericardial cavity: the transverse sinus and the oblique sinus.
The transverse pericardial sinus runs transversely in the pericardial sac between the origins of the great vessels: posterior to the
ascending aorta and pulmonary trunk and anterior to the superior vena cava.
The oblique pericardial sinus is a wide recess in the posterior wall of the pericardial sac bounded laterally by the entrances of the
pulmonary veins and inferiorly by the orifice of the inferior vena cava.
Blood supply to the layers of the pericardium is mainly from the pericardiacophrenic vessels, from the internal thoracic arteries and veins.
The nerve supply to the pericardium is from the phrenic nerves, primarily sensory fibers for pain, and the sympathetic trunks (vasomotor).page 110
page 111Heart
The heart is a muscular pump for the propulsion of blood to all parts of the body.
The right side of the heart receives poorly oxygenated blood from the superior and inferior vena cava and pumps it to the lungs for
oxygenation.
The left side of the heart receives oxygenated blood from the lungs via the pulmonary veins and pumps it to the body via the aorta and its
branches.
The heart consists of four chambers: the right and left atria and the right and left ventricles.
The chambers of the heart have walls that consist of three layers: