Abdominal aorta

The abdominal aorta is the main blood vessel in the abdominal cavity that transmits oxygenated blood from the thoracic cavity to the organs within the abdomen and to the lower limbs.

Summary
origin: continuation of descending thoracic aorta at T12
course: descends anterior and slightly to the left of the lumbar vertebral bodies
branches (unpaired)
celiac artery (T12)
superior mesenteric artery (L1)
inferior mesenteric artery (L3)
median sacral artery
branches (paired)
middle adrenal arteries
renal arteries (L1-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 between two crura of diaphragm
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 celiac and superior mesenteric artery origins
crossed anteriorly by the left renal vein, uncinate process of the pancreas and 3rd part of the duodenum between the superior mesenteric and inferior mesenteric artery origins
Gross anatomy
Origin
It is a continuation of descending thoracic aorta at T12 posterior to the median arcuate ligament and diaphragmatic crura.

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

Termination
It eventually terminates at the L4 level by bifurcating into right and left common iliac arteries. This is also where the origin of median sacral artery is, which descends along the middle of sacral promontory.

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

Single ventral branches (to the gut and related viscera)
celiac 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
four paired lumbar arteries
Single parietal branches
median sacral artery
Variant anatomy
variable level of bifurcation
right-sided aorta
coeliacomesenteric trunk
sinuous course
accessory renal artery
direct branches (e.g. splenic, hepatic, accessory hepatic, accessory SMA, internal iliac)
Related pathology
abdominal aortic aneurysm
abdominal aortic stenosis/occlusion: atherosclerosis, aortitis, Leriche syndrome
References
Related Radiopaedia articles
Anatomy: Abdominopelvic
skeleton of the abdomen and pelvis[+]
muscles of the abdomen and pelvis[+]
spaces of the abdomen and pelvis[+]
abdominal and pelvic viscera[+]
blood supply of the abdomen and pelvis
arteries
abdominal aorta
inferior phrenic artery
superior suprarenal artery
celiac artery
common hepatic artery (variant anatomy)[+]
left gastric artery
splenic artery[+]
superior mesenteric artery
inferior pancreaticoduodenal artery
jejunal and ileal branches
ileocolic artery[+]
right colic artery
middle colic artery
middle suprarenal artery
renal artery (variant anatomy)
inferior suprarenal artery
gonadal artery (ovarian artery | testicular artery)
inferior mesenteric artery
left colic artery
sigmoid arteries
superior rectal artery
lumbar arteries
median sacral artery
common iliac artery
external iliac artery[+]
internal iliac artery (mnemonic)[+]
portal venous system[+]
veins[+]
anastomoses[+]
lymphatics[+]
innervation of the abdomen and pelvis[+]