It runs parallel to the inferior vena cava, which is located just to the right of the abdominal aorta, and becomes smaller in diameter as it gives off branches.
The abdominal aorta supplies blood to much of the abdominal cavity. It begins at T12, and usually has the following branches:
|inferior phrenic||T12||Parietal||yes||post.||originates just below the diaphragm, supplying it from below|
|celiac||T12||Visceral||no||ant.||large anterior branch|
|superior mesenteric||L1||Visceral||no||ant.||large anterior branch, arises just below celiac trunk|
|middle suprarenal||L1||Visceral||yes||post.||to adrenal gland|
|renal||L2||Visceral||yes||post.||large artery, each arising from the side of the aorta; supplies corresponding kidney|
|gonadal||L2||Visceral||yes||post.||ovarian artery in females; testicular artery in males|
|lumbar||L1-L4||Parietal||yes||post.||four on each side that supply the abdominal wall and spinal cord|
|inferior mesenteric||L3||Visceral||no||ant.||large anterior branch|
|median sacral||L4||Parietal||no||post.||artery arising from the middle of the aorta at its lowest part|
|common iliac||L4||Terminal||yes||post.||branches (bifurcates) to supply blood to the lower limbs and the pelvis, ending the abdominal aorta|
Note that the bifurcation (union) of the inferior vena cava is at L5 and therefore below that of the bifurcation of the aorta.
Posteriorly, it is separated from the lumbar vertebræ and intervertebral fibrocartilages by the anterior longitudinal ligament and left lumbar veins.
On the right side it is in relation above with the azygos vein, cisterna chyli, thoracic duct, and the right crus of the diaphragm—the last separating it from the upper part of the inferior vena cava, and from the right celiac ganglion; the inferior vena cava is in contact with the aorta below.
On the left side are the left crus of the diaphragm, the left celiac ganglion, the ascending part of the duodenum, and some coils of the small intestine.