Anatomical Course and Topography
The splenic artery is a major branch of the celiac trunk (truncus coeliacus), which arises from the anterior surface of the abdominal aorta at the level of TXII–LI.
Vascular Topography:
- The artery courses tortuously along the superior border of the pancreas toward the splenic hilum.
- Initially, it lies posterior to the upper border of the pancreatic body, then runs superior to it.
- At the junction of the body and tail of the pancreas, it crosses onto its anterior surface.
- The vessel then enters the splenorenal ligament (lig. pancreaticolienale) to reach the hilum of the spleen.
- It is accompanied throughout its course by the splenic vein (v. splenica / v. lienalis).
- The splenic plexus (plexus splenicus) travels along the artery.
Age-Related Changes: In children and young adults, the artery is relatively straight. After the age of 30, it develops tortuosity, and past 60 years, it becomes markedly tortuous, sometimes adopting a spiral shape. The adult length ranges from 10–12 cm, but can extend up to 26–32 cm with advanced age.
Branches of the Splenic Artery
As it travels toward the spleen, the artery gives off several extra-organ branches to adjacent digestive organs:
- Pancreatic branches (rr. pancreatici) — supply the pancreatic parenchyma. These include the dorsal pancreatic artery (a. dorsalis pancreatis), greater pancreatic artery (a. magna pancreatica) supplying the body and tail, and the caudal pancreatic artery (a. caudae pancreatis).
- Short gastric arteries (aa. gastricae breves) — 3 to 7 small branches that course through the gastrosplenic ligament to supply the gastric fundus.
- Left gastro-omental artery (a. gastroepiploica sinistra) — travels along the greater curvature of the stomach from left to right, anastomosing with the right gastro-omental artery.
Intrasplenic Branching
At the splenic hilum, the main trunk divides into 2 branches (superior and inferior) in 80–90% of cases, and less frequently into 3–4 branches. Subsequent intra-organ branching follows this pathway:
- Splenic branches (rr. splenici) branch off within the hilum.
- Trabecular arteries (aa. trabeculares) — travel within the connective tissue trabeculae.
- Central arteries (aa. centrales) — enter the pulp and traverse the lymphoid follicles of the white pulp.
- Penicillar arterioles / Penicilli (penicilli) — fine terminal branches.
- Splenic sinusoids (sinus splenicus) — capillaries drain directly into venous sinusoids in a closed circulation, or empty into the reticular tissue of the red pulp in an open circulation.
Innervation
The vessel is innervated by the splenic plexus (plexus splenicus), which surrounds the artery. It is formed by branches from the left half of the celiac plexus, with contributions from the left suprarenal and left phrenic plexuses. The plexus carries visceral sensory, sympathetic, and parasympathetic fibers.
Clinical Significance
- Splenic Infarction: Anastomoses between intra-organ arterial branches are sparse and of small caliber. Thrombosis or embolism of a. lienalis branches frequently results in localized ischemic splenic infarction.
- Surgery (Splenectomy): During splenectomy, ligatures are placed close to the splenic hilum rather than on the main trunk of the a. lienalis to avoid injuring the tail of the pancreas. The artery is typically ligated first to reduce organ engorgement while venous outflow remains open, followed by double ligation of the v. lienalis.