Anatomy Atlas

Abdominal aorta

Pars abdominalis aortae
ArteryHigh-yielddraftCardio

Continuation of the thoracic aorta from the aortic hiatus (T12) to its bifurcation at L4. It supplies the abdominal organs and is the usual site of aortic aneurysm.

Core anatomy

Location

Retroperitoneal, on the anterior surface of the lumbar vertebral bodies, slightly left of the midline, with the inferior vena cava on its right.

Origin

Continuation of the descending thoracic aorta at the aortic hiatus of the diaphragm (T12).

Course

Descends anterior to the lumbar vertebrae to bifurcate at about L4 (roughly at or slightly below the umbilicus) into the right and left common iliac arteries.

Branches
  • Anterior (unpaired, to the gut): Celiac trunk (T12), superior mesenteric artery (L1), inferior mesenteric artery (L3)
  • Lateral (paired): inferior phrenic, middle suprarenal, renal (about L1–L2), gonadal (about L2)
  • Posterior: lumbar arteries (four pairs), median sacral artery
  • Terminal: right and left common iliac arteries (L4)
Supplies

Abdominal viscera, posterior abdominal wall, kidneys, suprarenal glands, gonads, and (via the iliacs) the pelvis and lower limbs.

Termination

Common iliac arteries at L4.

Relations

Anterior: pancreas and splenic vein, the left renal vein (which crosses between the aorta and the SMA), the 3rd part of the duodenum, and the root of the mesentery. Right: IVC, cisterna chyli, azygos vein. The sympathetic trunks run on each side of the vertebral bodies.

Branches

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.
Posterior abdominal wall showing the abdominal aorta, IVC, kidneys and their vessels
The abdominal aorta and its branches on the posterior abdominal wall.
Henry Vandyke Carter, Gray's Anatomy of the Human Body, 20th ed. (1918), Fig. 531. Source · Public domain (Public domain in the US: published before January 1, 1931 (per Wikimedia Commons))

Clinical correlations

Abdominal aortic aneurysm (AAA) PANCE

Mechanism / lesion

Dilation of the aorta to 3.0 cm or more, usually infrarenal. Risk factors: smoking (the strongest), male sex, age over 65, family history, hypertension, atherosclerosis.

Classic presentation

Usually asymptomatic, found on screening or incidental imaging. Rupture presents with the triad of severe abdominal or back/flank pain, hypotension and a pulsatile abdominal mass. Elective repair is generally recommended at 5.5 cm or more in men and 5.0 cm or more in women, with rapid growth, or when symptomatic. Surveillance ultrasound (SVS 2018): every 3 years at 3.0–3.9 cm, every 12 months at 4.0–4.9 cm and every 6 months at 5.0–5.4 cm.

AAA screening PANCE

Mechanism / lesion

Screening detects asymptomatic aneurysms before rupture.

Classic presentation

USPSTF: one-time abdominal ultrasound for men aged 65–75 who have ever smoked.

Aortoiliac occlusive disease (Leriche syndrome)

Mechanism / lesion

Atherosclerotic occlusion of the distal aorta and/or iliac arteries.

Classic presentation

Classic triad of buttock/thigh claudication, erectile dysfunction, and absent or diminished femoral pulses.

High-yield PANCE pearls

  • AAA = ≥ 3.0 cm; most are infrarenal; smoking is the strongest risk factor.
  • Screen: one-time ultrasound, men 65–75 who ever smoked (USPSTF).
  • Rupture triad: pain + hypotension + pulsatile mass → emergency surgery (unstable patients go straight to the OR).
  • Leriche: buttock claudication + ED + absent femoral pulses.
  • Branch levels: celiac T12, SMA L1, renals L1–L2, IMA L3, bifurcation L4.

Imaging anatomy

X-ray

Calcified aneurysm wall ("eggshell" calcification) on a lateral abdominal film. Not reliable for sizing.

CT

CT angiography is the test of choice for stable patients with suspected rupture and for planning repair (open or endovascular). It measures diameter, the neck length below the renal arteries, and iliac involvement.

Ultrasound

Screening and surveillance test (outer-to-outer wall diameter). Point-of-care ultrasound in the ED can quickly confirm an aneurysm in an unstable patient (though it cannot reliably show retroperitoneal rupture).

Key views & landmarks
  • Abdominal ultrasound (transverse and longitudinal aorta)
  • CT angiography abdomen/pelvis

Physical exam

Surface landmarks

The bifurcation lies at about L4, projecting near the level of the iliac crests (supracristal plane), slightly below the umbilicus.

Palpation

Palpate deeply above and to the left of the umbilicus with both hands to estimate the width of the aortic pulsation (an expansile pulsation wider than about 3 cm suggests AAA). Sensitivity is limited by body habitus. Don't palpate forcefully if a symptomatic aneurysm is suspected.

Strength / function testing

Auscultate for bruits (aortic, renal, iliac). Check femoral and distal pulses.

Self-quiz

Q1.

A 72-year-old man with a 50-pack-year smoking history has sudden severe back pain, BP 76/40, and a tender pulsatile periumbilical mass. What is the next step?

Show answer

B

The rupture triad (pain, hypotension, pulsatile mass) in an unstable patient calls for immediate repair. CT angiography is only for hemodynamically stable patients.

Q2.

Which patient should be screened for abdominal aortic aneurysm under USPSTF guidance?

Show answer

B

USPSTF recommends a one-time ultrasound for men aged 65–75 who have ever smoked. Screening in women who have never smoked isn't recommended.

Q3.

At approximately which vertebral level does the abdominal aorta bifurcate?

Show answer

D

The aorta bifurcates into the common iliac arteries at about L4. The IVC forms at about L5.

Q4.

A 58-year-old smoker has cramping pain in both buttocks and thighs when walking, erectile dysfunction, and diminished femoral pulses. What is the most likely diagnosis?

Show answer

D

Leriche syndrome (atherosclerotic occlusion of the distal aorta and/or iliac arteries) causes the triad of buttock/thigh claudication, erectile dysfunction and absent or diminished femoral pulses. Superficial femoral disease causes calf claudication with normal femoral pulses.

Q5.

Which vessel crosses anterior to the abdominal aorta, just below the origin of the superior mesenteric artery?

Show answer

A

The left renal vein crosses anterior to the aorta, between it and the SMA. Compression there ("nutcracker") can cause hematuria and a left varicocele. The right renal artery passes behind the IVC.

Flashcards

See also