What are the Layers of the Heart Wall?
Pericardium The pericardium is the double walled sac that contains the heart and the roots of the great vessels that leave from or enter the heart. There are two layers of the pericardial sac, which are the fibrous pericardium and the serous pericardium. The serous pericardium is further divided into two layers, which are the parietal pericardium and the visceral pericardium. The parietal pericardium is inseparably fused to the fibrous pericardium, while the visceral pericardium is actually a part of the epicardium, which is the outermost single layer of the pericardium. The visceral layer extends into the starting point of great vessels, thus, becoming one with the parietal layer of the serous pericardium. This happens where the aorta and pulmonary trunk leave the heart and where the two vena cavae (superior and inferior vena cava) and pulmonary veins enter the heart. In between the parietal and visceral layers lies a space which is known as the pericardial cavity. It is lubricated by
