Abdominal aorta

At a glance

English

Abdominal aorta

Latin (TA2)

Aorta abdominalis

System

Artery

Region

Trunk

Side

Single, on the midline

About the abdominal aorta

The abdominal aorta is the continuation of the thoracic aorta below the diaphragm. It enters the abdomen through the aortic hiatus, which lies behind the diaphragm between its two crura at the level of the twelfth thoracic vertebra, and descends in front of the lumbar vertebrae, just left of the midline. At about the fourth lumbar vertebra, near the level of the umbilicus, it ends by dividing into the right and left common iliac arteries. As it follows the forward curve of the lumbar spine it is closest to the front of the abdomen at about L3, and it narrows as it gives off its large branches.

Clinicians divide it into a suprarenal (visceral) segment, above the renal arteries, and an infrarenal segment between the renal arteries and the bifurcation. Its branches fall into three groups. Unpaired front branches go to the gut: the coeliac trunk near T12, the superior mesenteric artery at L1 and the inferior mesenteric artery at L3. Paired side branches go to glands and the kidneys: the middle suprarenal and renal arteries. Paired branches to the body wall are the inferior phrenic arteries to the diaphragm and four pairs of lumbar arteries. A small median sacral artery continues from the back of the bifurcation into the pelvis.

In front of the aorta, from above down, lie the coeliac plexus and lesser omentum, the pancreas and splenic vein, the left renal vein crossing to the inferior vena cava, the third part of the duodenum and the root of the mesentery. Behind are the left lumbar veins, the anterior longitudinal ligament and the lumbar vertebral bodies. On its right are the right crus, the cisterna chyli, the start of the azygos vein and, lower down, the inferior vena cava. On its left are the left crus, the duodenojejunal flexure and coils of small intestine.

Abdominal aortic aneurysm, usually below the renal arteries, is common in older smokers and can rupture; it is screened for with ultrasound and repaired by open graft or stent graft. Atherosclerosis may narrow the lower aorta and its bifurcation. When the aorta is slowly blocked, collateral channels such as the internal thoracic to inferior epigastric link and the connections between the mesenteric arteries can carry blood around the obstruction.

Course and supply

Arises from

Continues from the thoracic aorta as it passes through the aortic hiatus of the diaphragm at T12.

Ends in

Ends at about L4, a little left of the midline, by dividing into the right and left common iliac arteries, with the small median sacral artery continuing from its back.

Supplies

Supplies the abdominal organs through the coeliac, superior and inferior mesenteric arteries, the kidneys and suprarenal glands, the diaphragm and posterior abdominal wall, and through the common iliac arteries the pelvis and lower limbs.