The hilum of the kidney is a recessed central fissure on the medial surface of each kidney where its vessels, nerves, and ureter pass. It is a bundle of tubes, including blood vessels, nerves, and ureters, that acts as a gateway for the entry and exit of blood, urine, and nerves. The renal hilum is the entry and exit site for structures servicing the kidneys, including vessels, nerves, lymphatics, and ureters. The structures found in the renal hilum are arteries, veins, ureters, lymphatics, and nerves. The relative position of the main structures in the hilum is as follows: the vein is in front, the artery in the middle, and the ureter behind and directed downward.