The renal pelvis is located inside the renal sinus. The outside surface of each kidney is convex, while the side toward the center is deeply concave. The resulting middle depression leads into a hollow chamber called the renal sinus. The entrance to this sinus is termed the hilum, and through it passes various blood vessels, nerves, lymphatic vessels, and the ureter. The superior end of the uretermycontentbreak is expanded to form a funnel-shaped sac called the renal pelvis. The pelvis is divided into two or three tubes, called the major calyces (the singular is calyx), and they are divided into several (eight to fourteen) minor calyces.