Human kidneys are paired bean shaped organs situated in a retroperitoneal position on the posterior aspect of the abdominal cavity, on either side of vertebral column against psoas major muscle. Three layers of tissue surround each kidney. The deep layer, the renal capsule, is a smooth transparent fibrous membrane that is continuous with the outer ureter. The intermediate layer, the adipose tissue (perirenal fat) is a mass of fatty tissue surrounding the renal capsule. It protects the kidney from trauma and holds it firmly in place within the abdominal cavity. The superficial layer, the renal fascia, is a thin layer of dense irregular connective tissue that anchors the kidney to its surrounding structures and to the abdominal wall. A frontal section through the kidney reveals two distinct regions: a superficial reddish area called the renal cortex and a deep reddish brown region called the renal medulla.