Minor calyx
Calyx renalis minor
Also known as: minor calyces, calyx
A cup-shaped tube of the collecting system that embraces one (or more) renal papillae and receives urine from it; ≈7–13 per kidney.
Overview
Each minor calyx fits like a cup around a papilla; its rim (fornix) attaches around the base of the papilla. A minor calyx may receive one simple papilla or a compound papilla. Two or three minor calyces unite to form a major calyx. The walls of the calyces contain smooth muscle whose rhythmic contractions — initiated by pacemaker cells near the pelvicalyceal junction — begin the peristaltic propulsion of urine toward the ureter.
On imaging (urography, CT urography) normal minor calyces appear cupped, with sharp fornices indented by the papilla.
- Location
Within the renal sinus, surrounding each renal papilla.
Anatomy
- Histology
Urothelium, lamina propria and a thin smooth muscle coat; adventitia continuous with the sinus fat.
- Development
Derived from the ureteric bud (3rd–4th generation branches).
Function
- Collect urine from the papillary ducts
- Initiate peristalsis of the upper urinary tract
Clinical significance
Calyceal clubbing
Loss of the normal cupped shape (blunting, clubbing) indicates papillary destruction — chronic pyelonephritis/reflux nephropathy, papillary necrosis, tuberculosis, or hydronephrosis from obstruction.
Compiled from standard anatomy and physiology references — see the Urinary System sources. For education only; not medical advice.