346 SPECIAL ANATOMY. 



Branches : to the trunk of ven. portce also pass v. gastrica (sinis- 

 tra) superior and cystica ; from the trunk passes off in the Porta 

 (sinus v. portce) : 



a. Ramus dexter, the shorter and thicker branch for the right 

 lobe of the liver. 



b. Ramus sinister, for the left and the two central lobes, re- 

 ceiving in the embryo the right branch of the umbilical vein, and 

 gives offductus venosus Arantii, which unites v. portce and v. cava 

 inferior. 



The two branches pass off from one another at a right angle, 

 quickly divide, continually becoming smaller, and form, at last, 

 around the glandular lobules of the liver, a capillary rete, from 

 which the vv. hepaticcz come off. 



1. Lienalis s. splenica arises in the cells of the spleen, passes through the 

 Hilus and transversely to the superior border of the pancreas, behind and be- 

 low art. lienalis, towards the right to the mesenterica superior. It receives 

 vv. breves, pancreaticce, gastro-epiploica sinistra, and : 



a. V. mesenterica inferior. This arises from ven. hemorrlioid. superior in 

 the plexus hcemorrhoidalis of the rectum (therefore connected with v. hy- 

 pogastrica) and vv. colicce sinistrce; passes obliquely to the right and 

 above mesocolon descendens, before the vasa renal, and behind the pan- 

 creas to the splenic vein, near to its confluence with v. mesenterica su- 

 perior, in which it even' often opens. 



b. Mesenterica superior. It lies on the right and anterior side of the ar- 

 tery of the same name, arises from vv. colicce dextrce and intestinales, 

 gastroepiploic. dextra, and receives in the embryo the v. omphalo-mese- 

 raica from the umbilical vesicle, which in the third month of foetal life, 

 together with its artery, again disappears. 



Anastomoses of the portal vein : 1 . between the vv. hcemorrlioi- 

 dal. and hcemorrhoid. interna. 2. Between the veins of colon 

 transvers., descendens, and v. cava inferior. 



599. Vena umbilicalis, the umbilical vein, arises in the embryo 

 from the capillary rete formed by the two artt. umbilicales in the 

 Placenta. Passing through the umbilical cord and ring into the 

 belly of the foetus, it advances to the inferior sin-face of the liver 

 (in the left anterior longitudinal sulcus), and bifurcates into a 

 larger connecting branch for the left branch of the portal vein, and 

 a smaller left (ductus venosus Arantii), which carries the blood 

 into the ven. cava inferior. It becomes impervious (in one month) 

 after birth, and then passes as lig. teres hepatis. It is larger than 

 the portal vein of the foetus, and valveless. Branches : about 

 twenty small ones for the liver. 



