Various branches of the abdominal Aorta

KEY
A - Abdominal Aorta
G - Adrenolumbar Artery
B - Celiac Trunk
H - Renal Artery
C - Hepatic Artery
I - Gonadal Arteries
D - Left Gastric Artery
J - Inferior Mesenteric Artery
E - Splenic Artery
K - Iliolumbar Artery
F - Superior Mesenteric Artery
L - Femoral Artery

The abdominal aorta is a large-lumened, unpaired arterial vessel that is part of the main trunk of the systemic arterial system. As such, the abdominal aorta supplies oxygenated blood, pumped by the left ventricle of the heart, to the abdominal and pelvic organs and structures via visceral and parietal arterial branches.
The abdominal aorta and its major arterial branches are highly elastic. During systole (heart muscle contraction), the aortic and arterial walls expand to accommodate the increased blood flow. Correspondingly, the vessels contract during diastole and elastin fibers assure that this contraction also serves to drive blood through the arterial vessels.

As the thoracic aorta passes through the aortic hiatus (an opening in the diaphragm) it becomes the abdominal aorta. The abdominal aorta ultimately branches into left and right common iliac arteries. The common iliac arteries then branch into internal and external iliac arteries to supply oxygenated blood to the organs and tissues of the lower abdomen, pelvis, and legs.

Major branches of the abdominal aorta include, ventrally, the celiac branches, and superior and inferior mesenteric arteries. On the dorsal side of the aorta are the lumbar and median sacral branch arteries. Lateral to the aorta are the inferior phrenics, middle supernal, renal, and ovarian or testicular arteries. Because the branches from the abdominal aorta are large, the aorta rapidly decreases in size as it courses downward (inferiorly) through the abdomen.

The celiac trunk divides into three major branches: the left gastric artery to the stomach, the hepatic artery to the lobes of the liver, and splenic artery--surrounded by a plexus of nerves--that ultimately terminates in branches entering the hilus of the spleen.