splenic artery

**Origin and course** - It arises from the celiac trunk (T12), along with the common hepatic and left gastric arteries. - It is the largest celiac branch. It is tortuous and runs left along the superior border of the pancreas, behind the stomach (in the posterior wall of the lesser sac/stomach bed). - It passes through the splenorenal (lienorenal) ligament to reach the splenic hilum, together with the splenic vein (which lies inferior to the artery), the pancreatic tail, and lymphatics.

**Branches** - Pancreatic branches: dorsal pancreatic, pancreatica magna, and caudal pancreatic arteries. - Short gastric arteries: supply the fundus. They run in the gastrosplenic ligament. - Left gastroepiploic (gastro-omental) artery: supplies the greater curvature of the stomach and anastomoses with the right gastroepiploic artery (from the gastroduodenal artery). - Terminal splenic branches: usually 5-6 segmental (end) arteries at the hilum. Segmental infarcts can occur.

**Clinical significance** - Splenic artery aneurysm: the most common visceral artery aneurysm. It is more common in women and is associated with multiparity/pregnancy, portal hypertension, and fibromuscular dysplasia. Rupture in pregnancy is a high-mortality emergency. Treat if symptomatic, >2 cm, or in a woman of childbearing age. - Posterior gastric or duodenal ulcer erosion into the splenic artery can cause massive hemorrhage. Posterior gastric ulcers are the classic example, and they can also bleed into the lesser sac. - Splenic trauma: this is the most commonly injured solid organ in blunt abdominal trauma. Left-sided rib fractures (9-11) raise suspicion. Kehr sign is left shoulder pain from diaphragmatic irritation. Management ranges from observation to splenic artery embolization or splenectomy. - Splenectomy: ligation of the splenic artery and vein is done at the hilum. Care is needed to avoid injuring the pancreatic tail, which lies in the splenorenal ligament. A pancreatic leak or fistula can result. After splenectomy, the risk of infection with encapsulated organisms (S. pneumoniae, H. influenzae, N. meningitidis) rises, so vaccinate. Howell-Jolly bodies appear on smear. - Splenic infarction: arterial embolism (e.g., atrial fibrillation, endocarditis) or sickle cell disease causes a wedge-shaped infarct. It presents with LUQ pain. - Splenic artery steal syndrome: after liver transplantation, a high-flow splenic artery diverts blood from the hepatic artery, which can cause graft ischemia. - Pancreatitis: inflammation or pseudocysts can erode into the splenic artery (pseudoaneurysm) or thrombose the splenic vein, causing left-sided (sinistral) portal hypertension with isolated gastric varices. - Ischemia of the foregut: the celiac trunk supplies the foregut (distal esophagus to the 2nd part of the duodenum, liver, gallbladder, pancreas, spleen). Celiac artery compression by the median arcuate ligament causes postprandial pain. Collateral flow from the SMA via the pancreaticoduodenal arcades helps.

**Anatomy relationships** - Splenic vein: runs posterior and inferior to the artery, and joins the SMV behind the pancreatic neck to form the portal vein. Remember "the vein is straight, the artery is tortuous." - Splenic artery and pancreas: the artery lies along the superior border, and the tail lies in the splenorenal ligament. - Embryology: the spleen develops from mesoderm in the dorsal mesogastrium. It is not a foregut endoderm derivative, but it is supplied by the foregut (celiac) artery. - Venous drainage: the splenic vein goes to the portal system. - Lymphatic drainage: to pancreaticosplenic nodes, then celiac nodes.