944 A MANUAL OF ANATOMY 



superior vena cava; and the remaining four invest the pulmonary 

 veins. The inferior vena cava receives no sheath from the fibrous 

 portion, because that vessel opens into the right auricle of the 

 heart almost immediately after it passes through the foramen 

 quadratum in the central tendon of the diaphragm. 



The fibrous layer is attached to the sternum by two fibrous 

 bands, which are known as the superior and inferior sterno-peri- 

 cardial ligaments of Luschka, the former being attached to the deep 

 surface of the manubrium, and the latter to the deep surface of the 

 ensiform process. 



The serous portion is a typical serous membrane, and consists 

 of two layers, parietal and visceral, which together form a shut sac. 



The parietal portion lines the inner surface of the fibrous part, 

 to which it is closely adherent, and it also intimately covers the 

 upper surface of the central tendon of the diaphragm. 



The visceral portion, known as the epicardium, closely invests 

 the heart, and also the great vessels at its base more or less com- 

 pletely. The continuity between the parietal and serous portions 

 is established inferiorly along the inferior vena cava. Superiorly 

 the continuity is established along the great vessels at the base 

 of the heart about i| inches above it. In this situation the 

 serous portion forms an arterial sheath which encloses within it 

 the ascending aorta and trunk of the pulmonary artery, for, as 

 stated, about ij inches, this being the only complete sheath formed 

 by the serous portion. Behind this sheath, with its contents, and 

 in front of the auricular portion of the heart, there is a passage, 

 called the transverse sinus of the pericardium, which leads from the 

 right to the left side of the serous sac. The serous portion is also 

 related to the superior vena cava and the pulmonary veins, but it 

 only covers them in front and at the sides. 



The serous portion of the pericardium forms a triangular fold, 

 called the vestigial fold of Marshall, which is situated between the 

 left pulmonary artery and the upper left pulmonary vein. Its 

 base is directed towards the left, and its surfaces are anterior and 

 posterior. Between its two delicate layers there is a small fibrous 

 cord, which is a vestige of the left duct of Cuvier. 



The free surfaces of the parietal and visceral layers of the serous 

 portion are smooth, polished, and lubricated by serous fluid to 

 allow of free movement on the part of the heart. In the course 

 of pericarditis they become at first dry, and then roughened by 

 deposits of lymph, thus giving rise to the pericarditic friction 

 murmur, and, it may be, to adhesions. They may also become 

 separated from each other by effusion into the pericardial sac, thus 

 giving rise to the condition known as hydro-pericardium. 



Blood-supply. — The fibrous portion of the pericardium and the 

 parietal layer of the serous portion receive their arteries from 

 (i) the pericardial and superior phrenic branches of the internal 

 mammary, and (2) the descending thoracic aorta. The visceral 

 layer of the serous ])ortion receives arterial twigs from the coronary 

 arteries of the heart- 



