Kidney is bean shaped organ with a convex and a concave surface. It is internally distinguished in two functional regions: cortex part towards outer convex side and medulla towards inside.
Anatomy of kidney in LS (longitudinal section) is seen best in the diagram attached below. It shows three distinct areas within kidney: these are cortex, medulla and pelvis. An outlet, ureter, arises from renal pelvis located at concave curvature.
Renal medulla is divided in triangular renal pyramids. The renal cortex remains extended between pyramidal masses as Columns of Bertini.
Medulla is associated with nephrons and collecting ducts where urine becomes more concentrated.