328 A MANUAL OF ANATOMY. 



Tributaries. The right and left innominate veins, azygos 

 major, mediastinal and pericardial veins. 



The arteria comes nervi phrenic! is a very small 

 artery from the internal mammary to the phrenic nerve 

 just after the latter crosses the former. It accompanies 

 the nerve to the diaphragm. 



DISSECTION. 



Make a vertical and a transverse incision in the pericardium. 

 Reflect the flaps ; study the situation and relations of the heart and its 

 great vessels. 



The Pericardium. Figs. 68, 69. 



The pericardium is a fibrous sack enclosing the heart 

 and beginning of the great vessels. Below it is attached 

 to the central tendon of the diaphragm, mostly at the left, 

 of the median line ; above it passes on to the great vessels 

 and becomes continuous with the deep cervical fascia from 

 the neck. 



The fibrous pericardium is lined by a serous layer that 

 is also reflected on to the heart and beginning of the great 

 vessels. The portion of the serous membrane lining the 

 sack is the parietal, that reflected over the vessels and 

 heart is the visceral layer. 



The serous layer extends upward on to the beginning of 

 the great vessels for a distance of one or one and one-half 

 inches from the base of the heart. 



Relations. In front, sternum and cartilages from third 

 to the sixth inclusive, anterior intercostal muscles, trian- 

 gularis sterni, to some extent by the lungs and pleurae ; 

 laterally, pleurae, lungs, phrenic nerves, and accompany- 

 ing arteries ; posteriorly, bronchi, oesophagus, pneumo- 

 gastric nerves, descending aorta ; below, the diaphragm, 



