Splenic artery

Origin and course

The splenic artery is one of the three main branches of the celiac trunk, along with the left gastric and common hepatic arteries. It arises around the level of the lower border of the T12 vertebra. After its origin, it travels inferiorly for a short distance then rapidly turns to the left to run horizontally in a tortuous manner across the left crus of diaphragm and left psoas muscle, towards the spleen. Coursing along the superior border of the pancreas, it runs through the splenorenal ligament, anterior to the left kidney and its suprarenal gland, and posterior to the stomach.

Upon reaching the lateral margin of the pancreas, the artery ascends to enter the hilum of the spleen. Here, the splenic artery divides into its superior and inferior terminal branches, with each branch successively dividing into four to six segmental branches within the parenchyma of the spleen. Along its course, the splenic artery is accompanied by the splenic vein, which drains into the hepatic portal vein.

Branches and supply

Along its course, the splenic artery gives off several branches before entering the hilum of the spleen and dividing into its terminal branches. The pancreatic branches of the splenic artery arise from its proximal portion. These are the dorsal, inferior and great pancreatic arteries, and the artery to tail of pancreas. The distal part of the splenic artery gives off the gastric branches of the splenic artery; namely the short gastric arteries and the left gastroepiploic artery.

• Dorsal pancreatic artery: arises from the first part of the splenic artery. This artery descends along the posterior margin of the pancreas where it divides into left and right branches. The right - sided branches anastomose with the pancreaticoduodenal arcade (of Kirk) to supply the head and neck of the pancreas. The left branches anastomose with branches of the transverse pancreatic artery, supplying the body and tail of the pancreas.
• Inferior pancreatic artery: also called the transverse pancreatic artery, is typically considered a branch of the dorsal pancreatic artery. It arises either from the splenic artery directly or from the dorsal pancreatic artery. The inferior pancreatic artery gives off multiple branches that anastomose with other pancreatic branches of the splenic artery to supply the body and tail of the pancreas.
• Great pancreatic artery: arises from the middle part of the splenic artery. This is one the longest of the pancreatic branches, descending along the posterior margin of the pancreas or through the pancreas itself, alongside the pancreatic duct. It anastomoses with the inferior pancreatic artery to supply the tail and body of the pancreas.
• Short gastric arteries: usually consists of 5-7 arteries that arise to the left of the greater curvature of the stomach. These arteries course through the gastrosplenic ligament of the greater omentum to supply the cardiac orifice and fundus of the stomach. Along their course, they anastomose with branches of the left gastric and left gastroepiploic arteries.
• Left gastroomental artery: also named the left gastroepiploic artery, arises from the splenic artery near the hilum of the spleen. It runs to the right, between the layers of the greater omentum and along the greater curvature of the stomach. Roughly at the middle of the curvature, the left gastroepiploic artery anastomoses with the right gastroepiploic artery (a branch of the right gastro-duodenal artery originating from the hepatic branch of the coeliac trunk), which supplies the greater curvature of the stomach.

Anatomic variations

The splenic artery may have numerous anatomical variations in its origin, course and branches. Common variations include;

• The splenic artery most commonly arises from the celiac trunk but it may also originate from the abdominal aorta or the superior mesenteric artery.
• The splenic artery typically gives off branches as it runs its course above the pancreas. However, in around 30% of cases, branches may not arise until the splenic artery has almost reached the hilum of the spleen. In these cases, the splenic artery is called the magistral splenic. In the former more typical scenario, where the branches arise earlier, the splenic artery may be called the distributing splenic artery.
• The dorsal pancreatic artery arises from the splenic artery in about 40% of cases, while in the remaining cases it may either stem from the celiac, superior mesenteric or common hepatic artery.