Abdominal aorta

Segment · T12 to L4 Retroperitoneal IVC on right

Begins at the aortic hiatus (T12) and descends retroperitoneally, slightly left of the midline on the lumbar vertebral bodies, to bifurcate into the common iliac arteries at L4. Branches fall into three groups: unpaired visceral (coeliac T12, SMA L1, IMA L3), paired visceral (suprarenal, renal, gonadal) and parietal (inferior phrenic, lumbar, median sacral).

Detail

Level: T12 (aortic hiatus) to L4 (bifurcation)
Unpaired visceral: Coeliac trunk T12, superior mesenteric L1, inferior mesenteric L3
Paired visceral: Middle suprarenal L1, renal L1–L2, gonadal L2
Parietal: Inferior phrenic T12, four lumbar pairs L1–L4, median sacral just above the bifurcation
Relations: IVC to its right; left renal vein and third part of the duodenum cross in front just below the SMA origin

When it goes wrong

Abdominal aortic aneurysm (diameter over 3 cm; about 90% infrarenal; older male smokers)

Rupture gives abdominal or back pain, hypotension and a pulsatile expansile mass, though the full triad is present in under half of patients. Open or endovascular repair must spare the renal arteries and usually sacrifices the IMA

Saddle embolus or acute thrombosis at the aortic bifurcation

Sudden bilateral cold, pulseless, painful, paralysed legs from the groin down

Practise this structure

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