Organ
Ureteropelvic junction
The transition from renal funnel to ureter
High-yield
Junctional obstruction usually dilates the pelvis and calyces without comparable ureteral dilation. It is an important cause of antenatal hydronephrosis, but dilation alone does not prove obstruction.
Overview
The ureteropelvic junction is the narrowing transition between the renal pelvis and proximal ureter. Its position depends on the collecting-system configuration. Normal coordinated activity carries urine across it; impaired drainage may reflect intrinsic wall abnormalities or extrinsic distortion.
Reference facts
- Location
- Where the renal pelvis tapers into the upper ureter near the hilum; vertebral position and intrarenal or extrarenal extent vary.
- Parts
- A transition between the wider pelvic lumen and the tubular ureter, rather than a separate discrete valve.
- Blood supply
- Small renal arterial branches join the proximal ureteral adventitial network.
- Innervation
- Renal and upper ureteric plexuses carry autonomic fibers and lower thoracic/upper lumbar pain afferents; referral is variable.
- Relations
- Related to hilar tissues and psoas; a lower-pole vessel may cross anteriorly or nearby.
- Function
- Transfers urine from pelvis to ureter through coordinated smooth-muscle activity and an unobstructed lumen.
Clinical correlation
Obstruction may cause intermittent flank or abdominal pain, sometimes after increased urine production. A lower-pole crossing vessel can contribute in selected cases, although crossing vessels also occur without functional obstruction.
Frequently asked questions
Where is the ureteropelvic junction located?
Where the renal pelvis tapers into the upper ureter near the hilum; vertebral position and intrarenal or extrarenal extent vary.
What does the ureteropelvic junction do?
Transfers urine from pelvis to ureter through coordinated smooth-muscle activity and an unobstructed lumen.
What are the parts of the ureteropelvic junction?
A transition between the wider pelvic lumen and the tubular ureter, rather than a separate discrete valve.
What is the blood supply of the ureteropelvic junction?
The ureteropelvic junction is supplied by the small renal arterial branches join the proximal ureteral adventitial network.