THE HEART. 



61? 



inward, about an inch within the pericardium, to enter the 

 auricle. There is no valve at the entrance of this vein. 

 At the lower portion of the auricle the inferior cava is 

 seen to enter FIG. 199. 



obliquely hack- 

 ward and in- 

 ward, ascend- 

 ing within the 

 pericardium 

 onl y for a short 

 distance. 



At the en- 

 trance of this 

 vein there is a 

 valve, called 

 the valve of 

 Eus tachius, 

 which, in the 

 adult, is very 

 imperfect, but 

 in the foetus is 

 quite large, 



and, according to Sabatier, is obviously designed to conduct 

 the foatal blood to the foramen ovale, and prevent the mix- 

 ing of the superior and inferior ^streams. This valve is 

 formed by a doubling of the lining membrane of the auri- 

 cle, surrounding about one half of the front of the inferior 

 cava, and stretching between this vessel and the fossa 

 ovalis, with which it is connected. 



Between the two cava, about midway, is seen a transverse 

 prominence, called tuberculum Loiveri. The direction of the 

 blood, entering the auricle by these two veins, is such' 



FIG. 199 represents the right Heart laid open. 4 Superior cava. 8 Its 

 entrance into right auricle. 18 Inferior cava its entrance into the right 

 auricle. 13 Smooth portion of right auricle. 14 Eustachian valve. 15 mus- 

 culi pectinati. 9 Fossa ovalis, or remains of foramen ovale. 19 Annulus 

 ovalis. 22 Opening of coronary vein. 1 Cavity in right ventricle, leading to 

 the pulmonary artery. 11 Pulmonary artery. 12 Septum between ventricles. 

 3 Tricuspid valve. 6 Aorta. 



