6o LABORATORY DIRECTIONS 



and enters the right auricle. A number of veins enter the 

 inferior vena cava along its course. 



15. Lumbar Veins. — These are several small veins which 

 carry blood from the dorsal musculature to the vena cava. The 

 most cranial of the lumbar veins lies anterior to the diaphragm. 



16. Ilio-lumbar Veins. — These are the pair of veins enter- 

 ing the vena cava just anterior to the union of the common 

 iliac veins. They come from the surface of the neighboring 

 muscles. 



17. Internal Spermatic Vein {internal ovarian in females). 

 The right spermatic (ovarian) enters the inferior vena cava 

 about the level of the caudal end of the kidney. The left 

 spermatic (ovarian) usually enters the left renal vein. In males 

 the spermatic originates in the testis and passes through the 

 spermatic cord along with the vas deferens. In females, the 

 ovarian originates in the ovary and cranial end of the uterus and 

 passes medially to the vena cava or renal vein. 



18. Renal Vein. — Each originates in the kidney as two 

 branches which fuse together, sometimes before leaving the 

 kidney, sometimes immediately after. The renals enter the 

 vena cava as large veins. 



19. Adreno-lumbar Veins. — These veins pass over the sur- 

 face of the muscles in the neighborhood of the kidney and return 

 blood from the adrenal glands and enter the vena cava at about 

 the level of the cranial end of the kidney. 



20. Hepatic Veins. — These are a variable number of short 

 veins carrying blood from the liver to the vena cava. They 

 enter the vena cava just caudal to the diaphragm. To see them 

 cut into the substance of the liver. 



21. Portal System. — The portal vein, the main vein of this 

 system, breaks up into capillaries within the substance of the 

 liver. It is formed by the union of several veins leading from 

 the stomach and intestines. The largest of these are: 



a. The superior mesenteric, originating from many branches 

 and bringing blood from the small and large intestines. 



b. The inferior mesenteric, coming directly from the large 

 intestine. 



c. The gastro-splenic, formed by several branches carrying 

 blood from the stomach and spleen. It unites near the pyloric 



