The minor calyces form a cup-shaped drain around the apex of the renal pyramids.

Urine formed in the kidney passes through a renal papilla at the apex into the minor calyx; four or five minor calyces converge to form a major calyx through which urine passes into the renal pelvis (which in turn drains urine out of the kidney through the ureter).

The initiation is caused by the increase in volume that stretches the walls of the calyces.

This causes them to fire impulses which stimulate rhythmical contraction and relaxation, called peristalsis.

A "staghorn calculus" is a kidney stone that may extend into the renal calyces.