COLLATERAL CIRCULATION OF UPPER ABDOMINAL ORGANS
No other region in the body presents more diversified collateral pathways of blood supply than the foregut organs, the stomach, duodenum, pancreas, spleen, liver, and gallbladder. Because of the multiplicity of its blood vessels and the loose arrangement of its connective tissue, the greater omentum is exceptionally well adapted as a terrain of compensatory circulation, especially for the liver and spleen, when either the hepatic or splenic artery is occluded. The stomach may receive its blood supply from 6 primary and 6 secondary sources; the pancreas from the hepatic, splenic, and superior mesenteric; the liver from 3 primary sources (celiac, superior mesenteric, and left gastric) and, secondarily from communications with at least 23 other arterial pathways. In view of the relational anatomy of the splenic artery, it is quite obvious that most of the collateral pathways to the upper abdominal organs can be initiated via this vessel and its branches and completed through communications established by the gastroduodenal and superior mesenteric arteries.
The most important collateral pathways in the upper abdominal organs are the following:
1. Arcus arteriosus ventriculi inferior. This infragastric omental pathway is made by the right and left gastroomental arteries as they anastomose along the greater curvature of the stomach. The arc gives off ascending gastric and descending omental arteries.
2. Arcus arteriosus ventriculi superior. This supragastric pathway with branches to both surfaces of the stomach is made by the right and left gastric arteries anastomosing along the lesser curvature. Branches of the right gastric may unite with branches from the gastroduodenal, supraduodenal, posterior superior pancreaticoduodenal, or right gastroomental arteries. Branches of the left gastric artery may anastomose with the short gastric arteries from the splenic terminals, left gastroomental, branches from the recurrent cardioesophageal branch of the left inferior phrenic, or branches of an accessory left hepatic, derived from the left gastric.
3. Arcus epiploicus magnus. This omental pathway is situated in the posterior layer of the great omentum inferior to the transverse colon. Its right limb is made by the right omental artery from the right gastroomental artery, and its left limb by the left omental artery from the left gastroomental artery. Arteries involved in this collateral route include hepatic, gastroduodenal, right gastroomental, right omental, left omental, left gastroomental, and inferior terminal branches of the splenic.
4. Circulus transpancreaticus longus. This important collateral pathway is effected by connections between the dorsal pancreatic artery and splenic artery. The dorsal pancreatic may communicate with the first part of the splenic, hepatic, celiac, or superior mesenteric, depending on which artery gives rise to the dorsal pancreatic. At the tail end of the pancreas, it communicates with the splenic terminals via the great pancreatic artery, inferior pancreatic artery, and artery to the tail of the pancreas, and at the head of the pancreas with the gastroduodenal, superior pancreaticoduodenal, or right gastroomental arteries.
5. Circulus hepatogastricus. This is a derivative of the primitive, embryonic arched anastomosis between the left gastric and the left hepatic arteries. In the adult the arc may persist in its entirety; the upper half may give rise to an accessory left gastric, and the lower half to an “accessory” left hepatic from the left gastric artery.
6. Circulus hepatolienalis. Here an aberrant right hepatic or the entire common hepatic artery, arising from the superior mesenteric artery, may communicate with the splenic artery via a branch of the dorsal pancreatic or gastroduodenal, inferior pancreatic, or artery to the tail of the pancreas.
7. Circulus celiacomesentericus. Through the inferior pancreaticoduodenal, blood may be routed through the anterior and posterior pancreaticoduodenal arcades to enter the gastroduodenal artery, from which, via the right and left gastroomental arteries, it reaches the splenic, or, via the common hepatic, it reaches the celiac.
8. Circulus gastrolienophrenicus. This connection may exist (1) via a communication between the short gastric arteries from the splenic terminals and the recurrent cardioesophageal branches of the left inferior phrenic or (2) via a communication between the latter and the cardioesophageal branches given off by the left gastric, its aberrant left hepatic branch, or an accessory left gastric from the left hepatic.