Abdominal Aorta Branches

The aorta splits at L4 into the iliacs, but every branch above that has a vertebral address: when a vascular question gives you ischemia, the level tells you which organ is starving.

Home Repro Aorta Branches

A 67-year-old woman undergoes emergent repair of a ruptured abdominal aortic aneurysm. During surgery, the surgeon notes that an artery arising from the anterior surface of the aorta at the level of L2, just below the renal arteries, was damaged. Which structure is most likely to lose its blood supply?

A. Descending colon

B. Ovary

C. Sigmoid colon

D. Transverse colon

E. Spleen

THE PATTERN

One Pipe, Five Exits

The abdominal aorta is a highway. The branches are off-ramps. Each one has an address.

Think of the abdominal aorta like a vertical highway running from your diaphragm (T12) to your pelvis (L4). Along the way, arteries branch off at specific "mile markers" · the vertebral levels. Boards LOVE asking: "something got damaged at L-something, what structure is affected?"

The trick is knowing which off-ramp is at which mile marker. And here's the thing · it follows a logical pattern. The gut arteries go in order: foregut first, then midgut, then hindgut. And squeezed between them are the paired vessels to the kidneys and gonads.

The vertebral level tells you the artery. The artery tells you the organ. Board questions give you the level and expect you to name the organ (or vice versa). Learn the five levels and you can answer any of them. 🔑Twelve = Trunk (celiac). L1 = SMA (#1 gut artery). L2 = 2 gonads. L3 = IMA (last 3rd of gut). L4 = fork (bifurcation).

THE MAP

Tap Each Level

Click a vertebral level to see its branches and what they supply

T12

Celiac Trunk FOREGUT
Three branches: left gastric, splenic, common hepatic

Supplies: Stomach, spleen, liver, pancreas (head/body), proximal duodenum, abdominal esophagus.

The pattern: Foregut = everything the embryonic foregut became. The celiac trunk is the foregut's sole blood supply. Splenic artery is the most tortuous artery in the body (follows the pancreas). Left gastric gives off esophageal branches · that's why portal HTN causes esophageal varices (backup through left gastric).

SMA MIDGUT + Renal arteries PAIRED
Also: middle suprarenal arteries

SMA supplies: Duodenum (distal to ampulla) through splenic flexure of colon. The entire midgut.
Renal arteries: Paired, go directly to kidneys. Right renal crosses BEHIND the IVC.

SMA syndrome: SMA can compress the 3rd part of duodenum against the aorta, causing obstruction. Seen in rapid weight loss (loss of mesenteric fat pad). The aortomesenteric angle narrows.

Gonadal arteries PAIRED
Ovarian (female) / Testicular (male) · just below renals

Critical fact: These are DIRECT aortic branches. Not from the iliac, not from the renal. They come straight off the aorta at L2.

Ovarian artery travels through the infundibulopelvic (suspensory) ligament to reach the ovary. This ligament is the structure that gets ligated during oophorectomy · clamp the IP ligament, you clamp the ovarian artery and vein.

Testicular artery descends through the inguinal canal as part of the spermatic cord. Both gonadal arteries are long because the gonads migrated during development but kept their original blood supply.

IMA HINDGUT
Splenic flexure to upper rectum

Supplies: Descending colon, sigmoid colon, upper rectum.
Key branches: Left colic, sigmoid arteries, superior rectal artery.

Watershed areas: Splenic flexure (Griffith's point, SMA/IMA border) and rectosigmoid junction (Sudeck's point, IMA/internal iliac border). These are the first to die in low-flow states. That's why ischemic colitis loves the splenic flexure.

Common iliac bifurcation
Aorta splits into right and left common iliacs

Each common iliac splits into: External iliac (becomes femoral artery at inguinal ligament) and internal iliac (supplies pelvis, bladder, uterus, rectum).

Internal iliac branches include: Uterine artery, superior/inferior vesical, middle rectal, internal pudendal, obturator. The uterine artery crosses OVER the ureter at the level of the cervix ("water under the bridge" · ureter = water, uterine artery = bridge). This is why surgeons must be careful during hysterectomy.

THE TRAP ZONE

Gonadal Arteries: Direct Aortic Branches

This is where the question lives. They're NOT from the iliac.

The most commonly missed fact: ovarian and testicular arteries come directly off the aorta at L2. Students assume they branch from the internal iliac because the ovary is a pelvic organ. But embryologically, the gonads developed near the kidneys (at the level of the mesonephros) and migrated down during development. The arteries stayed attached to their original connection point.

Think of it like a phone charger. The gonads moved across the room but the cord stayed plugged into the same outlet (the aorta at L2). The cord just got longer. 🔑Gonads = Grew near kidneys, Got their own aortic branch. Never from iliac.

L2 vs L3 trap: "Artery just below the renals at L2" = gonadal (ovarian/testicular). "Artery at L3" = IMA. Boards love putting the IMA as a distractor when the question says L2. Read the vertebral level. If it says L2, the descending colon (IMA territory) is WRONG.

THE CONNECTIONS

Know the Ligaments

The ovarian artery doesn't just float · it travels in a specific structure

🔗

Infundibulopelvic (Suspensory) Ligament
Contains: ovarian artery + ovarian vein + lymphatics
Connects: ovary to pelvic sidewall. This is what you ligate during oophorectomy. Damage here = ovarian ischemia.

🔗

Ovarian (Proper) Ligament
Contains: NO major vessels
Connects: ovary to uterus. Just a fibrous tether. Easily confused with the IP ligament on boards, but this one is medial (toward uterus) while the IP ligament is lateral (toward sidewall).

🔗

Broad Ligament
Contains: uterine artery, round ligament, ovarian ligament
A peritoneal fold draping over the uterus like a tent. The IP ligament is the lateral extension of the broad ligament.

Which ligament has the ovarian artery? The infundibulopelvic, NOT the ovarian ligament (which connects ovary to uterus and has no major vessels). The names are deliberately confusing. IP = has the Important Pipe (artery). Ovarian ligament = just a tether.

THE TERRITORIES

Three Arteries, Three Gut Regions

Tap each card for the clinical detail

Foregut

Celiac Trunk (T12)

Stomach, liver, spleen, pancreas, proximal duodenum

Referred pain to epigastrium. Foregut structures share celiac plexus innervation. Peptic ulcer = epigastric pain = foregut.

Midgut

SMA (L1)

Distal duodenum to splenic flexure

Referred pain to periumbilical area. Appendicitis starts periumbilical (midgut origin of appendix) then migrates to RLQ. SMA is the most commonly embolized mesenteric artery.

Hindgut

IMA (L3)

Splenic flexure to upper rectum

Referred pain to suprapubic / hypogastric area. IMA territory is most vulnerable to ischemia at watershed areas: splenic flexure (Griffith's point) and rectosigmoid (Sudeck's point).

THE BRANCHES

Five Villains, Five Off-Ramps

Tap each card. Front = the vertebral level. Back = what it supplies and why it matters.

Celiac Trunk

T12 · Foregut Boss

Epigastric pain after eating. Three-pronged fork at T12. First branch off the abdominal aorta.

📷 Celiac trunk angiogram · tap to expand

tap to reveal

Level: T12 (diaphragm)

Branches: Left gastric + Splenic + Common hepatic

Supplies: Stomach, spleen, liver, pancreas, proximal duodenum

Referred pain: Epigastrium

Clinical pearl: Left gastric gives esophageal branches. Portal HTN causes esophageal varices via backflow through left gastric

SMA

L1 · Midgut Commander

Periumbilical pain. Supplies everything the midgut became. Most commonly embolized mesenteric artery.

tap to reveal

Level: L1

Supplies: Distal duodenum through splenic flexure

Also: Renal arteries exit at L1 (paired)

Referred pain: Periumbilical (appendix = midgut)

SMA syndrome: Rapid weight loss narrows aortomesenteric angle, compresses 3rd part of duodenum

Embolism: Most commonly embolized mesenteric vessel

Gonadal Arteries

L2 · The Travelers

Direct aortic branches at L2. Students always say "iliac." They're always wrong. The gonads moved. The blood supply didn't.

tap to reveal

Level: L2 (just below renals)

KEY: Direct aortic branches. NOT from iliac

Ovarian artery: Travels in infundibulopelvic (suspensory) ligament

Testicular artery: Through inguinal canal in spermatic cord

Why so long: Gonads developed at L2, migrated to pelvis/scrotum. Artery stayed plugged in

IMA

L3 · Hindgut Finisher

Ischemic colitis loves the splenic flexure. That's IMA vs SMA watershed. The most vulnerable spot in the colon.

tap to reveal

Level: L3

Supplies: Splenic flexure to upper rectum

Branches: Left colic, sigmoid arteries, superior rectal

Watershed #1: Splenic flexure = Griffith's point (SMA/IMA border)

Watershed #2: Rectosigmoid = Sudeck's point (IMA/internal iliac border)

AAA surgery: IMA origin often covered by graft. Check for sigmoid ischemia postop

Common Iliac Bifurcation

L4 · The Fork

The aorta ends here. Splits into right and left common iliacs. Umbilicus level. AAAs expand here before they rupture.

tap to reveal

Level: L4 (umbilicus)

Each iliac splits into: External iliac (femoral) + Internal iliac (pelvis)

Internal iliac supplies: Uterus, bladder, rectum, pelvic floor

Uterine artery: Crosses OVER ureter at cervix. "Water under the bridge." Hysterectomy complication = ureteral injury

AAA: 5 cm = repair threshold. Infrarenal is most common location

ALGORITHM

Abdominal Pain Location to Artery

Where is the pain? Walk the tree. Name the artery.

What is the pain location or the clinical scenario?

Epigastric pain (upper abdomen)

Periumbilical pain or RLQ migration

Left lower quadrant or hematochezia after aortic surgery

L2 damage question or gonadal/pelvic structure involved

BOARD PRACTICE

Name That Branch

5 surgeons need your help. Don't clip the wrong artery.