CorpusHuman Anatomy
UrinaryOrgan part

Renal pelvis

Pelvis renalis

Also known as: pelvis of kidney, pyelum

The funnel-shaped, expanded upper end of the ureter, formed by the confluence of the major calyces, that collects urine and narrows at the ureteropelvic junction.

Show on body map Kidney — Coronal Section

Overview

The renal pelvis lies partly within the renal sinus (intrarenal pelvis) and partly outside the hilum (extrarenal pelvis), where it is the most posterior of the hilar structures. It receives the major calyces and tapers inferomedially into the ureter at the ureteropelvic junction (UPJ) — the first of the three physiological ureteric narrowings, at about the level of the lower pole of the kidney/L2.

Its wall has the same layers as the ureter. The volume of a normal pelvis is ≈5–10 mL. Dilatation of the pelvis and calyces from obstruction is hydronephrosis; dilatation of the ureter as well is hydroureteronephrosis.

Location

Renal sinus and hilum, posterior to the renal vessels.

Parts & subdivisions

  1. Ureteropelvic junction
    Transition to the ureter; first site of narrowing and stone impaction.

Anatomy

Innervation

Renal plexus; pain referred to the loin (T10–L1).

Arterial supply

Branches of the renal artery; venous drainage to the renal vein.

Histology

Urothelium, lamina propria, two layers of smooth muscle (inner longitudinal, outer circular), adventitia.

Development

Ureteric bud — its dilated tip (ampulla) forms the pelvis.

Function

  • Collect urine from the calyces and channel it into the ureter
  • Coordinate peristalsis toward the ureter

Clinical significance

Ureteropelvic junction obstruction

The commonest cause of congenital hydronephrosis (intrinsic aperistaltic segment or a crossing lower-pole vessel); presents antenatally or with intermittent loin pain after fluid loads (Dietl crisis). Treated by pyeloplasty.

Pyelonephritis

Infection of the pelvis and renal parenchyma, usually ascending from the bladder; pelvic involvement explains the name (Greek pyelos, basin).

Test yourself

At the renal hilum, what is the usual order of the main structures from anterior to posterior?
  1. Renal artery, renal vein, renal pelvis
  2. Renal vein, renal artery, renal pelvis
  3. Renal pelvis, renal artery, renal vein
  4. Renal vein, renal pelvis, renal artery

Answer: Renal vein, renal artery, renal pelvis

VAP: the renal vein is most anterior, the renal artery is intermediate and the renal pelvis (continuing as the ureter) is most posterior.

More urinary system questions

Compiled from standard anatomy and physiology references — see the Urinary System sources. For education only; not medical advice.