Tuesday, June 3, 2014

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Visceral and parietal layer of serous pericardium


Pericardium
The pericardium is a fibroserous sac surrounding the heart and the roots of the great vessels. It consists of two components, 
1) the fibrous pericardium and 
2) the serous pericardium.

The fibrous pericardium is a tough connective tissue outer layer that defines the boundaries of the middle mediastinum. 

The serous pericardium is thin and consists of two parts:
1) The parietal layer lines the inner surface of the fibrous.
2) The visceral layer adheres to the heart and forms its outer covering.

The parietal and visceral layers of serous pericardium are continuous at the roots of the great vessels. The narrow space created between the two layers of serous pericardium, containing a small amount of fluid, is the pericardial cavity. This is pictured in the diagram above as a fist in a filled balloon. This potential space allows for the relatively uninhibited movement of the heart.



Fibrous pericardium
The fibrous pericardium is a cone-shaped bag with its base attached to the central tendon of the diaphragm
and a small muscular area on the left side of the diaphragm and its apex continuous with the adventitia of the great vessels. Anteriorly, it is attached to the posterior surface of the sternum by sternopericardial ligaments. 
These attachments help to retain the heart in its position in the thoracic cavity. The sac also limits cardiac 
distention.

Serous pericardium
The parietal layer of serous pericardium is continuous with the visceral layers of serous pericardium around the roots of the great vessels. These reflections of serous pericardium occur in two locations:
1) one superiorly, surrounding the arteries, the aorta and pulmonary trunk;
2) the second more posteriorly, surrounding the veins, the superior and inferior vena cava and the pulmonary veins.

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