THE PERICARDIUM. 

 Fig. 226. 



301 



Fig. 226. SEMI-DIAGRAHMAIIO VIEW OP THE PERICARDIUM FROM BEHIND, DESIGNED 



TO SHOW THE PRINCIPAL INFLECTIONS OF THE SEROUS SAC ROUND THE GREAT 



VESSELS, f 



The drawing is taken from preparations in which the heart and vessels had been 

 partially filled by injection, the pericardium inflated and dried in the distended state, and 

 the fibrous continuation on the vessels removed. By the removal of a portion of the 

 pericardium from behind the right and left cavities of the heart, the position of that 

 organ is made apparent. A bent probe is passed within the pericardium from behind 

 the right auricle in front of the vena cava inferior to the back of the left ventricle, which 

 may indicate the place where the large undivided sac of the pericardium is folded round 

 that vein. A, posterior surface of the right auricle ; A', the same of the left ; V, right 

 ventricle ; V, left ventricle ; Ao, the upper and back part of the aortic arch ; b, innomi- 

 nate artery ; C, vena cava superior ; az, azygos vein ; C', vena cava inferior between the 

 diaphragm and its union with the right auricle ; c" , great coronary vein ; +, cord of the 

 ductus arteriosus ; P, the right, P', the left pulmonary artery ; p, the right, p', the left 

 pulmonary veins ; D, the back of the central tendon of the diaphragm ; 1, the great 

 undivided sac of the pericardium proceeding from before backwards towards its inflections 

 round the vessels; 2, portion of this on the right side which partially surrounds the vena 

 cava superior, the upper and lower right pulmonary veins, and the vena cava inferior ; 3, 

 the portion of the left side which partially surrounds the vena cava inferior ; 4, the 

 portion which is extended upwards behind the left auricle, and partially folds over the 

 pulmonary arteries and veins, and which meets between these different vessels the 

 extensions of the main sac from the right and left ; 5, tubular portion of the pericardium 

 which completely surrounds the aortic and pulmonary arterial trunks. 



pulmonary vein. This is shown, by Marshall, to be a vestige of the cardiac termi- 

 nation of the great left anterior vein existing in early embryonic life. (Marshall, 

 " On the development of the great anterior Veins in Man and Mammalia," PMlosoph 

 Trans. 1850. Parti. See hereafter the figures of the coronary vein.) 



