How is the renal pelvis formed?
The renal pelvis is formed sequentially within the urinary collecting system:
- Renal papillae (papillae renales) — apices of the renal pyramids in the medulla. Each minor calyx receives 1–3 renal papillae.
- Minor calyces (calices renales minores) — typically 8–9 in number, enclosing the renal papillae.
- Major calyces (calices renales majores) — formed by the confluence of minor calyces. There are usually 2–3 major calyces per kidney.
- Renal pelvis (pelvis renalis) — formed by the convergence of the major calyces.
Where is the renal pelvis located?
The renal pelvis lies in the medial, concave border of the kidney known as the renal hilum (hilum renale). The hilum faces anteriorly and medially toward the aorta and inferior vena cava, leading into the renal sinus (sinus renalis).
Kidneys are retroperitoneal organs (retroperitonealiter) located on either side of the vertebral column at the level of Th12–L3. The renal hilum typically projects at the level of the first lumbar vertebra (L1) or the intervertebral disc between L1 and L2. The right kidney is usually situated slightly lower than the left.
Topography within the Renal Pedicle
The renal pelvis is a core component of the renal pedicle. In addition to the pelvis and the proximal ureter, the pedicle contains the renal artery (a. renalis), renal vein (v. renalis), nerve plexuses, and lymphatic vessels and nodes, all embedded in perirenal adipose tissue.
The spatial arrangement of the renal pedicle elements from posterior to anterior is:
- Renal pelvis and proximal ureter — the posterior-most element.
- Renal artery — located superior and anterior to the pelvis.
- Renal vein — the anterior-most and superior-most element of the complex.
Clinical Significance
In clinical practice and oncology, upper tract urothelial carcinoma is of major significance:
- Primary tumor localization within the upper urinary tract—whether in the renal pelvis or the ureter—is no longer considered an independent prognostic factor.
- The specific location of a tumor within the pelvicalyceal system versus the ureter does not alter tumor staging protocols.
Terminology and Grammar
- In Latin anatomical nomenclature, the term is pelvis renalis. The word pelvis is a third-declension feminine noun (pelvis, is f).
- The Greek combining form for the renal pelvis is pyelo-. The kidney itself is denoted by the root nephro-.