The medial border (margo medialis; internal border) is concave in the center and convex toward either extremity; it is directed forward and a little downward. Its central part presents a deep longitudinal fissure, bounded by prominent overhanging anterior and posterior lips. This fissure is named the hilum, and transmits the vessels, nerves, and ureter. Above the hilum the medial border is in relation with the suprarenal gland; below the hilum, with the ureter.
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. Frequently, however, branches of both artery and vein are placed behind the ureter