It begins as the continuation of the arch of aorta (where it loops over the heart to begin its descent), on the left side of the lower border of the 4th thoracic vertebra. It descends with an inclination to the right and terminates at the lower border of the 12th thoracic vertebra, in the aortic opening in the diaphragm (here now onwards, it is called abdominal descending aorta) from where it runs downwards and slightly to the left in front of lumbar vertebrae, and ends in front of the lower part of 4th lumbar vertebra, by dividing into right and left common iliac arteries.
At the commencement, it is situated to the left of vertebral column, it approaches median line as it descends and at its termination, it lies directly in front of vertebral column.
Anterior: root of left lung, heart, esophagus, and diaphragm. Posterior: vertebral column and hemiazygos veins. To the right: esophagus (in upper part), azygos vein, right lung and thoracic duct. To the left: left lung.
Posterior: to it are upper four lumbar vertebrae with their intervertebral disks. To the right: inferior vena cava, right crus of diaphragm. To the left: left crus of diaphragm, pancreas and duodenum.
Nine posterior intercostals arteries on each side (for the 3rd to 11th intercostal spaces)
Two left bronchial arteries (for lungs)
Esophageal branches (for esophagus)
Pericardial branches (for posterior surface of the esophagus)
Subcostal artery on each side (for abdominal wall)
Mediastinal branches (for posterior mediastinum)
Superior phrenic arteries (for diaphragm)
Ventral branches include celiac trunk, superior mesenteric artery and inferior mesenteric artery.
Lateral branches include right and left inferior phrenic, middle suprarenal, renal and testicular (in males) or ovarian (in females) arteries.
Dorsal branches include four pairs of lumbar arteries and a single median sacral artery.
Terminal branches as described above, includes the two common iliac arteries supplying the pelvis and lower limbs.