Pericardium. The structure of the pericardium.
Pericardium, pericardium (in the broad sense of the word), is a closed serous bag, in which two layers are distinguished: external fibrous, pericardium fibrosum, and internal serous, pericardium serosum. The outer fibrous layer passes into the adventitia of large vascular trunks, and is anteriorly attached to the inner surface of the sternum via short connective tissue cords, ligamenta sternope-ricardiaca. The inner serous layer (pericardium serosum), in turn, is divided into 2 sheets: visceral, or the above-mentioned epicardium, and parietal, spliced with the inner surface of pericardium fibrosum and lining it from the inside. Between the visceral and parietal sheets is a slit-like serous pericardial cavity, cavitas pericardialis, containing a small amount of serous fluid, liquor pericardii. On trunks of large vessels, at a close distance from the heart, the visceral and parietal sheets pass directly into each other. The unopened pericardium as a whole has the shape of a cone, the base of which grows together with the centrum tendineum diaphragmatis, and the blunt tip is directed upwards and covers the roots of large vessels. From the sides, the pericardium is adjacent directly to the mediastinal pleura of the one and the other side. With its posterior surface, the pericardial sac fits to the esophagus and descending aorta. The aorta and the pulmonary trunk are surrounded on all sides by a common leaflet of the pericardium. The passage behind the aorta and pulmonary trunk is called the transverse sinus of the pericardium, sinus transversus pericardii. Hollow veins and pulmonary veins are only partially covered with serous leaflets. The space bounded by the inferior vena cava below and to the right, the left pulmonary veins to the left and above, is sinus obliquus pericardii.