662 BLOOD-VASCULAR SYSTEM OF THE HORSE 



renal, posterior mesenteric, and internal spermatic or utero-ovarian. The parietal 

 branches are the lumbar arteries. 



I. The coeliac artery (A. coeliaca) is an unpaired vessel, usually half an inch 

 or less (ca. 1 cm.) in length, which arises from the ventral aspect of the aorta at its 

 emergence from the hiatus aorticus. It divides on the dorsal surface of the pan- 

 creas into three branches — the gastric, hepatic, and splenic. 



1. The gastric artery (A. gastrica sinistra) passes downward and forward in 

 the gastro-phrenic ligament, gives off oesophageal and pancreatic branches, 

 and divides above and behind the cardia into anterior and posterior branches. 

 The anterior branch (Ramus cranialis) crosses the lesser curvature just to the right 

 of the cardia and ramifies on the parietal surface of the stomach. The branches 

 pursue a flexuous course toward the greater curvature and anastomose with the 

 short gastric arteries and the gastric branch of the hepatic artery. The pos- 

 terior branch (Ramus caudalis) is distributed in a similar fashion on the visceral 

 surface. The oesophageal branch (Ramus oesophageus) passes through the hia- 

 tus oesophageus into the thoracic cavity above the cesophagus and anastomoses 

 with the oesophageal branch of the broncho-oesophageal artery. 



The -gastric artery often arises by a common trunk with the splenic. The two terminal 

 branches may arise separately, or the anterior from the splenic and the posterior from the hepatic. 

 The oesophageal branch often arises from the splenic or the posterior gastric. 



2. The hepatic artery (A. hepatica) is larger than the gastric. It passes for- 

 wartl and to the right and ventrally on the dorsal surface of the pancreas, covered by 

 the gastro-pancreatic fold, crosses obliquely under the vena cava, and reaches the 

 medial border of the portal vein. It divides into three or four branches which enter 

 the portal fissure of the liver and ramify within the gland with the portal vein and 

 the hepatic duct. It gives off the following collateral branches: (1) Pancreatic 

 branches (Aa. pancreaticae) are given off as the artery crosses the pancreas, in 

 which it is partly embedded. (2) The pyloric artery (A. gastrica dextra) arises 

 above the first curve of the duodenum. It descends to the pylorus, sending branches 

 to the pylorus and the first part of the duodenum, and anastomoses with the gastric 

 and right gastro-epiploic arteries. It may arise from the gastro-duodenal. (3) 

 The gastro-duodenal artery (A. gastroduodenalis) passes to the second curve of the 

 duodenum and divides into the right gastro-epiploic and the pancreatico-duodenal. 

 The right gastro-epiploic artery (A. gastroepiploica dextra) crosses over the posterior 

 surface of the duodenum and enters the greater omentum, in which it runs to the 

 left, parallel with the greater curvature of the stomach. It gives branches to the 

 latter and to the omentum and forms an anastomotic arch with the left gastro- 

 epiploic artery. The pancreatico-duodenal artery (A. pancreaticoduodenalis) 

 divides into pancreatic and duodenal branches. The former (Ramus pancreaticus) 

 supplies the middle part of the pancreas and is often replaced by a number of 

 variable twigs. The duodenal branch (Ramus duodenalis) passes to the right along 

 the lesser curvature of the duodenum and anastomoses with the first branch of the 

 anterior mesenteric artery. 



Variations in the branching of the hepatic artery are not imcommon. The pancreatico- 

 duodenal may arise directly from the trunk, and there may be a common trunk for the pyloric and 

 right gastro-epiploic which runs along the dorsal surface of the first curve of the duodenum to the 

 pylorus; here it gives off the small pyloric branch and is continued across the parietal surface 

 of the pylorus as the right gastro-epiploic. No gastro-duodenal trunk is present. 



3. The splenic artery (A. lienalis) is the largest branch of the coeliac. It passes 

 to the left (with the large satellite vein) on the left extremity of the pancreas and 

 across the saccus caecus of the stomach. Entering the suspensory ligament of the 

 spleen, it runs in the hilus of the spleen to the apex, beyond which it is continued 

 as the left gastro-epiploic. It gives off the following branches: (1) Pancreatic 

 branches (Rami pancreatici), which supply the left extremity of the pancreas. 



