Abdominal Aorta

General Characteristics and Classification of Branches

Descending through the abdominal cavity, the aorta bifurcates at the level of the fourth lumbar vertebra (L4) into the right and left common iliac arteries (aa. iliacae communes). The unpaired median sacral artery (a. sacralis mediana) continues downward as a slender prolongation of the main trunk along the anterior surface of the sacrum to the coccyx.

All branches arising from the abdominal aorta are divided into four main groups:

• Unpaired visceral branches (to the GI tract and spleen);
• Paired visceral branches (to the kidneys, adrenal glands, and gonads);
• Paired parietal branches (to the abdominal and back walls);
• Unpaired parietal branch (median sacral artery).

Unpaired Visceral Branches

This group supplies blood to the entire gastrointestinal tract within the abdominal cavity, as well as the liver, pancreas, and spleen.

1. Celiac trunk (truncus coeliacus). The most superior large vessel, which quickly trifurcates into:
2. Left gastric artery (a. gastrica sinistra) — runs toward the lesser curvature of the stomach, giving off esophageal branches.
3. Common hepatic artery (a. hepatica communis) — courses rightward toward the hepatoduodenal ligament. It divides into the gastroduodenal artery (a. gastroduodenalis) and the proper hepatic artery (a. hepatica propria). The latter runs within the portal triad, dividing into right (giving off the cystic artery) and left branches.
4. Splenic artery (a. splenica) — the largest and most tortuous branch of the celiac trunk. It runs along the superior border of the pancreas, supplying pancreatic branches, short gastric arteries, and the left gastro-omental (gastroepiploic) artery.

1. Superior mesenteric artery (SMA) (a. mesenterica superior). Supplies the small intestine and the right half of the large intestine. Its branches include:
2. Inferior pancreaticoduodenal artery;
3. Jejunal and ileal arteries (aa. jejunales et ileales) — form a complex system of anastomosing arches (arcades) within the mesentery;
4. Ileocolic (a. ileocolica), right colic, and middle colic arteries (a. colica dextra et media) — supply the ileocecal junction, appendix, ascending colon, and part of the transverse colon.

1. Inferior mesenteric artery (IMA) (a. mesenterica inferior). Supplies the left regions of the large intestine, forming anastomoses with the middle colic artery.

Paired Visceral Branches

These vessels arise symmetrically on either side of the aorta to supply organs of the retroperitoneal space and pelvis:

• Middle suprarenal (adrenal) arteries (aa. suprarenales mediae) — arise between the celiac trunk and the superior mesenteric artery, heading toward the adrenal glands.
• Renal arteries (aa. renales) — large trunks originating at the L1–L2 vertebral level. The right renal artery is longer than the left and passes posterior to the inferior vena cava. Both frequently give rise to inferior suprarenal arteries and ureteric branches.
• Gonadal arteries — testicular arteries (aa. testiculares) in males and ovarian arteries (aa. ovaricae) in females. They descend along the psoas major muscle. The testicular artery enters the inguinal canal, while the ovarian artery descends into the lesser pelvis within the suspensory ligament of the ovary.

Parietal Branches

Supply blood to the muscles, fasciae, and skin of the abdominal and lumbar wall:

• Inferior phrenic arteries (aa. phrenicae inferiores) — arise immediately below the aortic hiatus of the diaphragm. They give off superior suprarenal branches.
• Lumbar arteries (aa. lumbales I–IV) — four pairs of vessels running posterior to the psoas major muscle. They provide dorsal branches to back muscles, spinal branches to the vertebral canal, and anterior branches supplying the abdominal wall.
• Median sacral artery (a. sacralis mediana) — a slender, unpaired trunk supplying the sacrum and coccyx.

Major Interarterial Anastomoses

The abdominal cavity features an extensive collateral network of critical surgical importance:

• Gastric arcades: the left and right gastric arteries anastomose along the lesser curvature; the left and right gastro-omental arteries anastomose along the greater curvature.
• Pancreaticoduodenal zone: superior pancreaticoduodenal arteries (from the celiac trunk) connect with inferior pancreaticoduodenal arteries (from the SMA), securing a vital link between these two major vascular territories.
• Marginal artery of Drummond: formed along the inner border of the colon. A key anastomosis links the left branch of the middle colic artery (SMA territory) with the left colic artery (IMA territory).
• Intra-intestinal arcades: jejunal and ileal branches form multiple tiers of arcades. The jejunum has fewer arcades and longer straight vessels (vasa recta); the ileum features multiple tiers of arcades and short straight vessels.