The kidneys are reddish-brown, bean-shaped organs situated retroperitoneal on the posterior abdominal wall. They extend from lumbar vertebra T12-L3. Normally the kidney is about the size of a mouse and measures approximately 11-12 cm in length, 5-6 cm in width and 2.5-3 cm in thickness.The kidneys have a superior and inferior pole, medial and lateral margins, and an anterior and posterior surface. The superior pole of each kidney is deep to the rib cage.or the right kidney, its superior pole is at the 12th rib and for the left the superior pole is at ribs 11 and 12. Anatomy of Kidney. On the medial margin of the kidney is concave region called the renal hilus.