Abdominal Aorta

The abdominal aorta originates from the aortic hiatus in the diaphragm and extends downward to the L4 vertebra. At the L4 vertebra, it bifurcates into the left and right common iliac arteries while continuing as the median sacral artery into the sacrum. The aorta is positioned leftward of the spinal column, encased within adipose tissue behind the peritoneal cavity.

The celiac trunk, an unpaired visceral artery, divides into three main branches: the left gastric artery, splenic artery, and common hepatic artery. These branches supply blood to the stomach, esophagus, spleen, liver, gallbladder, upper duodenum, and pancreas. The celiac trunk is the first major branch of the abdominal aorta.

The superior mesenteric artery, arising approximately 2.5 cm below the celiac trunk, supplies the small intestine (duodenum, jejunum, and ileum), pancreas, and a large section of the large intestine. The inferior mesenteric artery, starting about 5 cm above the common iliac arteries, supplies the distal segment of the large intestine and the rectum.

The paired visceral branches of the abdominal aorta include the suprarenal (adrenal) arteries, renal arteries, and gonadal arteries. The renal arteries emerge approximately 2.5 cm below the superior mesenteric arteries and supply each kidney. The gonadal arteries are named the ovarian arteries in females or testicular arteries in males.

The parietal branches include the unpaired median sacral artery and the paired inferior phrenic and lumbar arteries. The median sacral artery supplies the sacrum, coccyx, and spinal nerves. The inferior phrenic arteries nourish the diaphragm, while the four pairs of lumbar arteries supply the lumbar vertebrae, abdominal wall, and spinal cord.

At the L4 vertebra, the abdominal aorta bifurcates into the left and right common iliac arteries, which supply blood to the pelvic region and lower limbs. These arteries divide into external and internal iliac arteries around the lumbar-sacral articulation. The internal iliac arteries supply the urinary bladder, pelvic walls, external genitalia, and in females, the uterus and vagina.

The right renal artery is longer than the left because the abdominal aorta is positioned leftward of the spinal column. This anatomical asymmetry reflects the aorta's leftward orientation relative to the vertebral column, requiring the right renal artery to extend a greater distance to reach the right kidney.