Major calyx
Calyx renalis major
Also known as: major calyces
One of usually 2–3 (superior, middle, inferior) large channels formed by the union of minor calyces, which converge to form the renal pelvis.
Overview
The major calyces are short, broad tubes within the renal sinus, each formed by the confluence of two to four minor calyces. Typically there is a superior, an inferior and sometimes a middle major calyx; they open into the funnel-shaped renal pelvis. Some kidneys have no distinct major calyces, the minor calyces opening directly into a large (ampullary) pelvis.
Like the minor calyces, they are lined by urothelium and have smooth muscle that transmits peristaltic waves.
- Location
Renal sinus, between the minor calyces and the renal pelvis.
Anatomy
- Histology
Urothelium over a lamina propria and smooth muscle layer.
- Development
Ureteric bud (2nd-generation branches).
Function
- Convey urine from minor calyces to the renal pelvis
Clinical significance
Staghorn calculus
Struvite (or cystine) stones can grow to cast the renal pelvis and major and minor calyces, forming a branched "staghorn" stone that usually requires percutaneous nephrolithotomy.
Compiled from standard anatomy and physiology references — see the Urinary System sources. For education only; not medical advice.