Quick Facts
The minor renal calyx is the smaller renal calices that receive urine from the renal papillae and open into the major calices (Dorland, 2011).
Structure and/or Key Feature(s)
The minor renal calyces (minor calyx is singular) are described as small chambers of the kidneys, through which urine passes. Specifically, renal filtrate from the renal papilla drain into minor calyces, and into major calyces thereafter. There are approximately 5–11 minor calyces in the kidney, each of which are considered funnel-shaped expansions of the upper urinary tract.
Identified as cup-shaped structures, the minor calyces are composed of a transitional epithelium, an underlying lamina propria, and smooth muscle (Dudek, 2006). The smooth muscle layer of the calyces undergoes rhythmic peristaltic movement to facilitate the flow of renal filtrate.
Anatomical Relations
The minor renal calyces are positioned at the apex of the renal pyramids. Together with the major renal calyces, they form the renal pelvis.
Function
Pacemaker cells in the smooth muscle layer of the minor calyces are responsible for initiating peristalsis and propulsion of urine into the major calyces.
References
Dorland, W. (2011) Dorland's Illustrated Medical Dictionary. 32nd edn. Philadelphia, USA: Elsevier Saunders.
Dudek, R. W. (2006) High-yield KidneyLippincott Williams & Wilkins.
