Branches of the aorta

32 named structures.

Draft — not yet clinically reviewed. The structure of this map is checked automatically, but its wording has not been fact-checked against a textbook. Do not rely on it for an exam answer yet.

Clinical detail

Common questions

What are the vertebral levels of the abdominal aortic branches?

Coeliac trunk T12, superior mesenteric L1, renal L1–L2 (usually quoted as L2), gonadal L2, inferior mesenteric L3, bifurcation into common iliacs L4. The aorta enters the abdomen through the aortic hiatus at T12 and the common iliacs divide at L5–S1 on the pelvic brim.

What is the order of the arch branches and how does the right side differ from the left?

Right to left: brachiocephalic trunk, left common carotid, left subclavian. The right common carotid and right subclavian arise from the brachiocephalic trunk, so the left common carotid has a longer thoracic course. In about 1 in 5 people the left common carotid shares an origin with the brachiocephalic trunk (the so-called bovine arch).

Why can repair of a thoracoabdominal aneurysm cause paraplegia?

The anterior spinal artery below the cervical cord depends on segmental feeders from the aorta, chiefly the artery of Adamkiewicz, which usually arises from a left posterior intercostal or lumbar artery between T9 and T12. Cross-clamping, covering or dividing these ostia infarcts the anterior two-thirds of the cord: paraplegia with loss of pain and temperature but preserved proprioception and vibration.

Why are the splenic flexure and rectosigmoid the sites of ischaemic colitis?

They are watersheds between arterial territories. At the splenic flexure (Griffiths' point) the ascending left colic must meet the middle colic through the marginal artery, and that link is poor or absent in about 40% of people. At the rectosigmoid (Sudeck's point) the last sigmoid artery meets the superior rectal. In low-flow states these zones lose perfusion first.

What is the difference between Stanford type A and type B dissection?

Type A involves the ascending aorta, whatever the site of the tear, and needs emergency surgery because it can occlude a coronary ostium, cause aortic regurgitation or rupture into the pericardium. Type B spares the ascending aorta, typically beginning just beyond the left subclavian origin, and is managed with blood-pressure control unless a branch (intercostal, renal, mesenteric, iliac) is compromised.

Where is the aortic bifurcation on the surface, and why does it matter?

At L4, in the plane joining the highest points of the iliac crests and roughly at the level of the umbilicus. A pulsatile mass above the umbilicus is the classic surface sign of an abdominal aortic aneurysm, and the level marks where a lumbar puncture needle (L3/4 or L4/5) is placed well below the conus.