BRANCHES OF THE ABDOMINAL AORTA 713 



arch, passes dovm on the lateral side of the lateral digit, and is distributed like the 

 medial one. 



BRANCHES OF THE THORACIC AORTA 

 The bronchial and oesophageal arteries often arise separately. 

 There are thirteen pairs of intercostal arteries. The first comes from the 



dorsal, the next four from the subcostal, and the remainder from the aorta directly. 

 The two phrenic arteries are very variable in origin. They may come from 



the aorta, the coeliac, left ruminal, or an intercostal or lumbar artery. 



BRANCHES OF THE ABDOMINAL AORTA 

 The coeliac artery is about four to five inches (ca. 10-12 cm.) in length. It 

 passes ventrally and curves forward between the rumen and pancreas on the left 

 and the right crus of the diaphragm and the posterior vena cava on the right. It 

 gives off five chief branches. 



1. The hepatic artery arises from the convex side of the curve of the coeliac 

 artery as it crosses the posterior vena cava. It passes downward, forward, and to 

 the right above the portal vein to the portal fissure, and gives off the following 

 branches : 



(1) Pancreatic branches. 



(2) Dorsal and ventral branches go to the corresponding lobes of the liver. 

 The ventral branch is the larger; it gives off the right gastric artery, which runs in 

 the lesser omentum to supply the origin of the duodenum and the pylorus, anas- 

 tomosing with the dorsal branch of the omaso-abomasal artery. 



(3) The cystic artery supplies the gall-bladder. 



(4) The gastro-duodenal artery divides into right gastro-epiploic and pan- 

 creatico-duodenal branches. The right gastro-epiploic artery anastomoses with 

 the left gastro-epiploic. The pancreatico-duodenal artery anastomoses with the 

 first intestinal branch of the anterior mesenteric artery. 



2. The right ruminal artery (A. ruminalis dextra) is the largest branch, and 

 usually arises by a short common trunk with the splenic. It runs downward and 

 backward on the right face of the dorsal sac of the rumen to the posterior transverse 

 fissure, in which it turns around to the left and anastomoses with branches of the 

 left ruminal artery. It gives off a pancreatic branch, dorsal and ventral coronary 

 arteries, branches to the great omentum, and ramifies on both surfaces of the rumen. 



3. The left ruminal artery (A. ruminalis sinistra) descends on the anterior part 

 of the right face of the rumen, enters the anterior furrow, in which it runs from 

 right to left, and continues backward in the left longitudinal groove, anastomosing 

 with branches of the right artery. It supplies chiefly the left face of the rumen, 

 but not its posterior part. It usually gives off near its origin the reticular artery 



(A. reticularis) ; this rather small vessel passes forward on the dorsal curvature of 

 the rumen and turns downward in the rumino-reticular groove, in the bottom of 

 which it runs around ventrally to the right side. It gives off a branch which passes 

 to the left of the cardia and along the lesser curvature of the reticulum to the neck 

 of the omasum. The reticular branches anastomose with the omaso-abomasal and 

 left ruminal arteries. 



4. The omaso-abomasal artery (A. gastrica sinistra) appears as the continua- 

 tion of the coeliac. It passes forward and downward to the greater curvature of 

 the omasum, and divides after a course of four or five inches into two branches. 

 The dorsal branch curves sharply backward on the dorsal surface of the omasum, 

 continues along the lesser curvature of the abomasum, and anastomoses with the 

 hepatic artery. It supplies branches to the omasum and to the lesser curvature 



