THORAX AND ABDOMEN OF THE HORSE 129 



by the union of the left colic and cranial hcemorrhoidal vessels, and 

 receives the middle colic vein and possibly also the small vein that 

 assists in draining the right dorsal colon. 



(3) V. lienalis. — This should rather be called the gastro-splenic 

 vein, since it helps materially to drain the wall of the stomach. 

 Beginning as the left gastro-epiploic vein, it receives short gastric and 

 pancreatic tributaries corresponding to branches of the splenic artery. 

 Into it also flows the caudal gastric vein. 



Into the stem of the portal vein formed as indicated above the 

 following tributaries open: — (a) Pancreatic branches, {b) The gastro- 

 duodenal vein, which begins as the right gastro-epiploic and receives 

 the pancreatico-duodenal. (c) The cranial gastric vein, which drains 

 the cranial surface of the stomach, opens into the portal vein (or 

 possibly one of its three main divisions) at the porta of the liver. 



Within the substance of the liver the portal vein behaves after the 

 manner of an artery, inasmuch as it divides and re-divides until 

 its smallest branches open into the sinusoids of the liver lobules. 



The blood brought to the liver by the portal vein, as well as that 

 brought by the hepatic artery, flows away by the hepatic veins (vv. 

 hepaticse), the openings of which into the caudal vena have already been 

 noted in the examination of this large vessel as it lies in the fossa venae 

 cavse on the diaphragmatic surface of the liver. 



Lymph glands are associated with each of the three branches of the 

 cceliac artery. Gastric lymph glands (lymphoglandulse gastricae) are 

 diffused and generally small. A group lies in the lesser curvature of 

 the stomach ; a small group is associated with the caudal gastric artery ; 

 a few lie on the saccus caecus; two or three small glands are related to 

 the ventral aspect of the pylorus ; and a scattered chain of small glands 

 follows the gastro-epiploic arteries. Hepatic lymph glands (lympho- 

 glandulae hepatica?) are associated with the portal vein and hepatic 

 artery in the neighbourhood of the porta of the liver. Splenic lymph 

 glands (lymphoglandulae lienales) lie along the hilus of the spleen in 

 association with the splenic vessels. 



Truncus cesophageus ventralis. — Within the thorax each vacuus 

 nerve divides into a dorsal and a ventral branch. The two dorsal 

 branches unite to form the dorsal oesophageal trunk ; the two ventral 

 branches in like manner form the ventral oesophageal trunk. 



The ventral oesophageal trunk, the smaller of the two, follows the 



oesophagus through the diaphragm and divides into many small nerves 



that form a plexus (plexus gastricus) over the cranial surface of the 



stomach. The larger filaments of the plexus follow the lesser curvature 

 9 



