PART IV 



THE VASCULAR SYSTEMS 



THE PERICARDIUM 



THE pericardium is a fibroserous membrane which invests the 

 heart and the great vessels at their origin for about two inches. 

 Below, it is attached to the diaphragm and its central tendon; 

 in front it is separated from the sternum by the thymic remains, 

 some areolar tissue, and overlapped by the margins of the lungs, 

 especially, of the left; behind it are the esophagus, bronchi, and 

 descending aorta; laterally it is covered by the pleurae, with the 

 phrenic nerve and vessels running between the two membranes. 



The pericardium consists of a fibrous and a serous layer. 

 The fibrous layer is attached below to the diaphragm and its 

 central tendon. Above, it forms a tubular investment for the 

 great vessels which is lost on the external coat, and may be 

 traced above into the pretracheal portion of the deep cervical 

 fascia, and in front is attached to the posterior surface of the 

 sternum by the superior and inferior sternopericardial ligaments 

 (Luschka). The vessels invested are the aorta,' superior vena 

 cava, both pulmonary arteries, and all the pulmonary veins. 



The serous layer invests the heart and is reflected to the 

 fibrous layer. It also invests the great vessels for about two 

 inches. The aorta and pulmonary artery are completely in- 

 vested, thus between them and the auricles posteriorly is the 

 transverse pericardial sinus. The pulmonary veins and both 

 the vense cavse are only partially invested. 



THE HEART 



The heart is a hollow muscular organ, of somewhat conical 

 form, lying between the lungs and enclosed by the pericardium, 

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