Anatomy Atlas

Superior mesenteric artery

Arteria mesenterica superior
Also: SMA
ArteryHigh-yielddraftCardioGI

Artery of the midgut, arising from the aorta at L1 behind the pancreas. Its occlusion causes acute mesenteric ischemia, and its angle with the aorta explains SMA and nutcracker syndromes.

Core anatomy

Location

Arises about 1 cm below the celiac trunk at about L1, behind the neck of the pancreas.

Origin

Abdominal aorta

Course

Descends anterior to the left renal vein, the uncinate process of the pancreas, and the 3rd part of the duodenum, then enters the root of the mesentery toward the right iliac fossa.

Branches
  • Inferior pancreaticoduodenal arteries
  • Jejunal and ileal arteries (from its left side), forming arcades and vasa recta
  • Middle colic artery (transverse colon)
  • Right colic artery (ascending colon)
  • Ileocolic artery (terminal ileum, cecum, appendix via the appendicular artery)
Supplies

Midgut: duodenum distal to the major papilla, jejunum, ileum, cecum, appendix, ascending colon, and the proximal two-thirds of the transverse colon.

Anastomoses

Pancreaticoduodenal arcades with the celiac trunk; the marginal artery and middle colic–left colic connection with the inferior mesenteric artery.

Relations

The left renal vein passes between the SMA and the aorta; the 3rd part of the duodenum also passes between them. The superior mesenteric vein lies to its right.

Structures supplied

Mentioned in

Generated automatically from links in other entries.

Arterial supply of the gutCeliac trunk at T12 supplies the foregut, the superior mesenteric artery at L1 the midgut, and the inferior mesenteric artery at L3 the hindgut. The aorta bifurcates at L4.T12L1L2L3L4Abdominal aortaCeliac trunkSMAIMARenal aa.Common iliac aa. (L4)Foregutpain → epigastricStomachDuodenum (to papilla)LiverGallbladderPancreasSpleen**mesoderm; celiac supplyMidgutpain → periumbilicalDistal duodenum,jejunum and ileumAppendixcecum, ascending colon,proximal 2/3 of transverse colonHindgutpain → suprapubicDistal 1/3 transverse colon,descending and sigmoid colonUpper rectum (superior rectal a.)Watershed: splenic flexure, rectosigmoid

Swipe sideways to see the whole diagram →

Arterial supply of the gut. The three unpaired anterior branches of the abdominal aorta and their territories, with vertebral levels and where visceral pain from each region is felt.
Original schematic, created for this atlas.
Colon reflected upward showing the superior mesenteric artery supplying the small intestine and right colon
The superior mesenteric artery and its branches to the small intestine and right colon.
Henry Vandyke Carter, Gray's Anatomy of the Human Body, 20th ed. (1918), Fig. 534. Source · Public domain (Public domain in the US: published before January 1, 1931 (per Wikimedia Commons))

Clinical correlations

Acute mesenteric ischemia PANCE

Mechanism / lesion

Embolism (often from atrial fibrillation or recent MI; typically lodges a few cm beyond the origin, sparing the proximal jejunum), thrombosis of an atherosclerotic origin, non-occlusive ischemia (low-flow states), or mesenteric venous thrombosis.

Classic presentation

Sudden severe abdominal pain out of proportion to the exam, nausea, vomiting, possibly bloody stool. Lactate rises late. CT angiography; treatment is emergency revascularization and resection of dead bowel.

Chronic mesenteric ischemia PANCE

Mechanism / lesion

Atherosclerotic stenosis of usually two or more mesenteric arteries.

Classic presentation

"Intestinal angina": postprandial pain 15–60 minutes after eating, food fear, and weight loss, in a patient with vascular disease.

SMA syndrome and nutcracker syndrome

Mechanism / lesion

A narrowed aortomesenteric angle compresses the 3rd part of the duodenum (SMA syndrome) or the left renal vein (nutcracker syndrome).

Classic presentation

SMA syndrome causes postprandial pain and vomiting after rapid weight loss. Nutcracker causes hematuria, left flank pain and a left varicocele.

High-yield PANCE pearls

  • SMA (L1) = midgut: distal duodenum → proximal 2/3 transverse colon.
  • Pain out of proportion to exam + AF → SMA embolus → CT angiography.
  • Chronic mesenteric ischemia: postprandial pain + food fear + weight loss.
  • Left renal vein and 3rd part of duodenum pass between SMA and aorta.

Imaging anatomy

X-ray

Late signs of ischemia (pneumatosis intestinalis, portal venous gas, thumbprinting). Often normal early.

CT

CT angiography is the test of choice for acute mesenteric ischemia (filling defect, bowel wall changes, pneumatosis). Sagittal images show the SMA origin and the aortomesenteric angle.

Ultrasound

Duplex screens for SMA stenosis (elevated peak systolic velocity) in chronic mesenteric ischemia; limited by bowel gas.

Key views & landmarks
  • CT angiography (arterial phase, sagittal reformats)

Physical exam

Palpation

A soft abdomen with minimal tenderness despite severe pain is the classic early finding in acute mesenteric ischemia. Peritoneal signs appear late (infarction).

Strength / function testing

Listen for an epigastric bruit. Look for atrial fibrillation (irregularly irregular pulse).

Self-quiz

Q1.

The SMA supplies which part of the colon?

Show answer

C

The SMA supplies the midgut, including the cecum, ascending colon and proximal two-thirds of the transverse colon (via the ileocolic, right colic and middle colic arteries).

Q2.

A 64-year-old woman with vascular disease has abdominal pain 30 minutes after meals, has lost 9 kg, and now avoids eating. What is the most likely diagnosis?

Show answer

B

Intestinal angina: postprandial pain, food fear and weight loss from atherosclerotic mesenteric stenosis (chronic mesenteric ischemia).

Q3.

Which vessel passes between the SMA and the abdominal aorta?

Show answer

B

The left renal vein crosses anterior to the aorta beneath the SMA. Compression here (nutcracker syndrome) can cause hematuria and a left varicocele.

Q4.

A thin young man has hematuria, left flank pain and a left varicocele. Imaging shows compression of the left renal vein. Between which structures is it compressed?

Show answer

E

In nutcracker syndrome, a narrow aortomesenteric angle compresses the left renal vein between the SMA and aorta, causing hematuria, left flank pain and a left varicocele. The same angle compresses the duodenum in SMA syndrome.

Q5.

Which branch of the SMA supplies the appendix?

Show answer

B

The appendicular artery is a branch of the ileocolic artery, which also supplies the terminal ileum and cecum. The left colic artery belongs to the IMA.

Flashcards

See also