THE THORAX. 



Structure of the Pericardium. The pericardium is a fibro-serous membrane, 

 and consists, therefore, of two layers, an external fibrous and an internal serous. 



The fibrous layer is a strong, dense membrane. Above, it surrounds the great 

 vessels arising from the base of the heart, on which it is continued in the form 

 of tubular prolongations which are gradually lost upon their external coat, the 

 strongest being that which encloses the aorta. The pericardium may be traced 

 over these vessels, to become continuous with the deep layer of the cervical fascia. 

 On each side of the ascending aorta it sends upward a di vertical um : the one on. 



Right 

 common 

 carotid J 

 artery 



Inf. thyroid vein 

 Right innom. 

 vein. 



^Right subdavian artery. 



fT.eft carotid. 



Left subdavian. 



Dtictua 

 arteriosus. 



FIG. 692. Pericardium, from in front. The sac has been distended with plaster. (From a preparation in the 

 Museum of the Royal College of Surgeons.) 



the left side, somewhat conical in shape, passes upward and outward, between the 

 arch of the aorta and the left pulmonary artery, as far as the ductus arteriosus, 

 where it terminates in a csecal extremity, which is attached by loose connective 

 tissue to the obliterated duct (Fig. 692). The one on the right side passes up- 

 ward and to the right, between the ascending aorta and vena cava superior, and 

 also terminates in a caecal extremity. Below, the fibrous layer is attached to the 

 central tendon of the Diaphragm, and on the left side to its muscular fibres. 

 Anteriorly the pericardium is connected to the sternum by two variable bands of 

 fascia, the superior and inferior sterno-pericardial ligankents of Luschka. 



The vessels receiving fibrous prolongations are the aorta, the superior vena cava, 

 the right and left pulmonary arteries, and the four pulmonary veins. As the infe- 

 rior vena cava enters the pericardium, it receives no covering from the fibrous layer. 



