Superior mesenteric artery
Unpaired trunk · Midgut T10–T11
Arises at L1 about 1 cm below the coeliac trunk, passes behind the neck of the pancreas and splenic vein, then forward over the uncinate process, third part of the duodenum and left renal vein into the root of the mesentery. Artery of the midgut: distal duodenum to the proximal two-thirds of the transverse colon.
Traced from the start
- Abdominal aorta
- Superior mesenteric artery
Detail
- Level
- L1, behind the pancreatic neck
- Supplies
- Midgut: D2 (distal to papilla) to D4, jejunum, ileum, caecum, appendix, ascending colon, proximal 2/3 transverse colon
- Branches
- Inferior pancreaticoduodenal, 12–15 jejunal and ileal, middle colic, right colic, ileocolic
- Crosses in front of
- Left renal vein, uncinate process, 3rd part of duodenum
- Referred pain
- Periumbilical, T10–T11 via lesser splanchnic nerve
When it goes wrong
Cardiac embolus (AF, recent MI, valve disease) lodges a few centimetres beyond the origin, distal to the middle colic take-off
Acute mesenteric ischaemia: sudden severe periumbilical pain out of proportion to a soft abdomen, vomiting and forceful bowel emptying, then peritonitis and lactic acidosis; proximal jejunum and transverse colon are spared
Loss of the mesenteric fat pad (rapid weight loss, anorexia, burns, spinal surgery) narrows the aortomesenteric angle below 25°
SMA syndrome: 3rd part of the duodenum is pinched between SMA and aorta — postprandial bilious vomiting and early satiety, eased by lying prone or on the left side
Low-flow state (cardiogenic shock, vasopressors, dialysis) without occlusion
Non-occlusive mesenteric ischaemia in the elderly; patchy midgut and watershed colon necrosis with high mortality
Practise this structure
1 question in the bank tagged Mesenteric Arterial Supply.