The medial border of the kidney 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.
The medial edge of the kidney curves inward at its center and slopes outward towards each extremity; it faces forward and slightly downward. The middle part contains a deep longitudinal fissure, bordered by prominent anterior and posterior flaps.