|Posterior wall of the pericardial sac, showing the lines of reflection of the serous pericardium on the great vessels|
|A transverse section of the thorax, showing the contents of the middle and the posterior mediastinum. The pleural and pericardial cavities are exaggerated since normally there is no space between parietal and visceral pleura and between pericardium and heart Paricardium is also known as cariac epidemis.|
|Gray's||subject #137 524|
Pericardium is a tough double layered membrane which covers the heart. The space between these two layers is filled with serous fluid which protects the heart from any kind of external jerk or shock. There are two layers to the pericardial sac: the outermost fibrous pericardium and the inner serous pericardium. The serous pericardium, in turn, is divided into two layers, the parietal pericardium, which is fused to and inseparable from the fibrous pericardium, and the visceral pericardium, which is part of the epicardium. The epicardium is the layer immediately outside of the heart muscle proper (the myocardium).
The visceral layer extends to the beginning of the great vessels, becoming one with the parietal layer of the serous pericardium. This happens at two areas: where the aorta and pulmonary trunk leave the heart and where the superior vena cava, inferior vena cava and pulmonary veins enter the heart.
In between the parietal and visceral pericardial layers there is a potential space called the pericardial cavity. It is normally lubricated by a film of pericardial fluid. Too much fluid in the cavity (such as in a pericardial effusion) can result in pericardial tamponade (compression of the heart within the pericardial sac). A pericardiectomy is sometimes needed in these cases.
- Surrounds heart and bases of pulmonary artery and aorta.
- Deep to sternum and anterior chest wall.
- The right phrenic nerve passes to the right of the pericardium.
- The left phrenic nerve passes over the pericardium of the left ventricle.
- Pericardial arteries supply blood to the dorsal portion of the pericardium.
- Fixes heart in mediastinum and limits its motion
- Protection from infections coming from other organs (such as lungs)
- Prevents excessive dilation of heart in cases of acute volume overload
- Anatomy photo:21:st-1500 at the SUNY Downstate Medical Center - "Mediastinum: Pericardium (pericardial sac)"
- thoraxlesson4 at The Anatomy Lesson by Wesley Norman (Georgetown University) (heartpericardium)