Abdominal aorta

The abdominal aorta is the main blood vessel in the abdominal cavity and transmits oxygenated blood from the thoracic cavity to the organs within the abdomen and to the lower limbs. It is a continuation of descending thoracic aorta at T12 posterior to the median arcuate ligament and diaphragmatic crura. It descends caudally in the retroperitoneum, anterior and slightly to the left of the lumbar vertebral bodies. The IVC lies to its right.

Between the coeliac and superior mesenteric artery origins, it is crossed anteriorly by the splenic vein and body of pancreas. and between the superior mesenteric and inferior mesenteric artery origins, it is crossed anteriorly by the left renal vein, uncinate process of pancreas and 3^rd part of the duodenum.

It eventually terminates at the L4 level by bifurcating into right and left common iliac arteries.

Branches

Branches of the abdominal aorta can be thought of as belonging to a number of groups.

Single ventral branches (to the gut & related viscera)

• coeliac artery (T12)
• superior mesenteric artery (L1)
• inferior mesenteric artery (L3)

Paired branches to other viscera

• middle adrenal arteries
• renal arteries (L2)
• gonadal arteries (between L2 and L3)

Paired branches to abdominal wall

• inferior phrenic arteries
• 4 lumbar arteries

Other

• median sacral artery

Related pathology

• abdominal aortic aneurysm
• abdominal aortic stenosis/occlusion: atherosclerosis, aortitis, Leriche syndrome

Summary

• origin: Continuation of descending thoracic aorta at T12 
• course: descends anterior and slightly to the left of the lumbar vertebral bodies.
• branches (unpaired):
  • coeliac artery (T12)
  • superior mesenteric artery (L1)
  • inferior mesenteric artery (L3)
  • median sacral artery
  branches (paired):
  
  • middle adrenal arteries
  • renal arteries (L2)
  • gonadal arteries (between L2 and L3)
  • inferior phrenic arteries
  • lumbar arteries
• termination: bifurcates into right and left common iliac arteries at L4
• key relationships:
  • posterior to the median arcuate ligament
  • anterior and slightly to the left of the lumbar vertebral bodies
  • IVC is on its right
  • crossed anteriorly by the splenic vein and body of pancreas between the coeliac and superior mesenteric artery origins
  • crossed anteriorly by the left renal vein, uncinate process of pancreas and 3^rd part of the duodenum between the superior mesenteric and inferior mesenteric artery origins