Abdomen Anatomy · Vascular

Superior Mesenteric Artery Branches

The SMA arises at L1 behind the pancreatic neck, supplying the midgut from D3–D4 to the distal two-thirds of the transverse colon.

✦ The Mnemonic

"Intestinal Midgut Routes: Inferior, Middle, Right Ileocolic"

5 named branches: IPC · Middle colic · Right colic · Ileocolic · Jejunoileal

IPC Inferior Pancreaticoduodenal First branch; anastomoses with SPC — critical collateral with celiac

MCA Middle Colic Supplies transverse colon; anastomoses with left colic via Drummond's marginal artery

RCA Right Colic Supplies ascending colon; often arises from ileocolic or MCA

IC Ileocolic Most constant SMA branch; supplies terminal ileum, caecum, appendix

JI Jejunal + Ileal Branches 12–18 branches forming vascular arcades; diminish distally

📚 Clinical Breakdown

The SMA crosses anterior to D3. SMA syndrome: SMA compresses D3 between itself and the aorta after rapid weight loss — postprandial pain, nausea, vomiting.

The ileocolic artery is the most constant SMA branch, terminating as the appendicular artery — an end artery. Thrombosis from appendicitis leads directly to gangrene without collateral rescue.

SMA occlusion (embolism 50%, thrombosis 25%) = catastrophic midgut ischaemia. Classic: sudden periumbilical pain out of proportion to signs, often with atrial fibrillation (embolic source). CT angiography confirms — time to revascularisation is critical.

SMA territory D3 to distal 2/3 transverse colon

Most constant branch Ileocolic

SMA embolism source Left atrial thrombus in AF

Critical collateral IPC ↔ SPC pancreaticoduodenal arcade

⭐ Clinical Pearl

Mesenteric angina: postprandial pain with weight loss from fear of eating. Usually requires two-vessel disease (SMA + celiac or SMA + IMA). The arc of Riolan (meandering mesenteric artery) — a large SMA–IMA collateral — enlarges dramatically in chronic occlusion.

← Celiac Trunk Next: IMA Branches →