Ureter Anatomy: Course, Constrictions, and Wall Structure

1) Ureter wall layers and how structure supports peristalsis

Mucosa (urothelium + lamina propria): a distensible, urine-proof lining

The ureter is a muscular tube designed to transport urine under low pressure while tolerating intermittent distension. Its innermost lining is urothelium (transitional epithelium), supported by a lamina propria. The mucosa forms longitudinal folds when the ureter is empty, so the lumen often appears stellate (star-shaped) in cross-section. This folding allows rapid expansion when a bolus of urine passes without tearing the lining.

• Barrier function: Urothelium limits urine permeability, protecting underlying tissues from solutes.
• Clinical tie-in: Because the mucosa is folded, a mildly distended ureter on imaging can look dramatically different from a collapsed ureter; interpreting caliber changes requires correlating with expected narrowing points and upstream dilation.

Muscularis: the engine of peristalsis

The ureter’s peristalsis is generated by smooth muscle arranged primarily in inner longitudinal and outer circular layers (with an additional outer longitudinal layer becoming more prominent in the distal ureter). Coordinated contraction propagates a wave that pushes discrete urine boluses toward the bladder, even against gravity.

• Functional design: Longitudinal fibers shorten the segment; circular fibers narrow the lumen behind the bolus, producing forward propulsion.
• Peristaltic pattern: Waves occur intermittently rather than as a constant squeeze; this is why ureter caliber can vary along its length on a single scan.
• Practical example: A small stone may intermittently obstruct: pain can be colicky because peristaltic waves repeatedly push against the obstruction.

Adventitia: fixation, vessels, and surgical relevance

The outer layer is adventitia, a connective tissue sheath that anchors the ureter to surrounding retroperitoneal tissues and carries its vessels, lymphatics, and nerves. The ureter’s blood supply is segmental and approaches from nearby arteries along its course; therefore, the adventitia is crucial for maintaining perfusion.

• Surgical principle: When mobilizing the ureter, preserve periureteral adventitial tissue to avoid devascularization.
• Imaging cue: The ureter is often identified by tracing a thin soft-tissue structure with tiny accompanying vessels in the retroperitoneum, especially when contrast opacifies urine.

2) Abdominal course: renal pelvis to pelvic brim (key landmarks)

Step-by-step tracing on anatomy or CT

To reliably find the ureter, trace it as a continuous structure from a known starting point to a known endpoint. In the abdomen, it is a retroperitoneal structure that descends on the posterior abdominal wall.

1. Start at the ureteropelvic junction (UPJ): Identify the funnel-shaped renal pelvis narrowing into the ureter.
2. Follow inferiorly on the psoas major: The ureter typically runs anterior to the psoas major muscle. On axial imaging, look for it near the medial aspect of the psoas.
3. Note its relationship to gonadal vessels: The gonadal vessels commonly cross anterior to the ureter in the abdomen; learners often remember this as “vessels cross the ureter.”
4. Approach the pelvic brim: Continue tracing until the ureter reaches the level where it will cross the iliac vessels to enter the pelvis.

Landmarks and relationships that help you not lose the ureter

• Retroperitoneal position: It stays behind the peritoneum; if you are looking within intraperitoneal spaces, you are too anterior.
• Psoas major as a guide: The ureter’s vertical descent is often easiest to follow along the psoas contour.
• Medial-to-lateral nuance: The ureter is not perfectly straight; it can show gentle curves as it navigates vessels and pelvic entry.

3) Pelvic course and approach to the bladder

Entering the pelvis: from brim to lateral pelvic wall

After crossing the iliac vessels at the pelvic brim, the ureter descends along the lateral pelvic wall toward the bladder. In the pelvis, it remains extraperitoneal and is closely related to pelvic vessels and fascia.

Continue in our app.

• Listen to the audio with the screen off.
• Earn a certificate upon completion.
• Over 5000 courses for you to explore!

Or continue reading below...

Download the app

• General path: It courses anteriorly and medially as it approaches the bladder.
• Clinical tie-in: Pelvic pathology (masses, inflammation, postoperative scarring) can compress the ureter along the lateral pelvic wall, producing upstream hydroureter and hydronephrosis.

Approach to the bladder: oblique intramural segment

Near the bladder, the ureter turns to enter the bladder wall and traverses an oblique intramural course before opening at the ureteric orifice. This obliquity functions as a flap-valve: bladder filling and contraction compress the intramural ureter, helping prevent reflux of urine back toward the kidney.

• Functional design: A longer intramural tunnel generally improves anti-reflux behavior.
• Imaging cue: The distal ureter may be difficult to see when not opacified; delayed-phase contrast studies can outline the intramural segment as it enters the bladder.

Sex-specific relationship highlights (high-yield for procedures)

While the overall course is similar, the ureter has key relationships that matter during pelvic surgery.

• Female: The ureter passes close to the uterine artery near the cervix (commonly summarized as “water under the bridge,” with the ureter as water). This is a classic site of iatrogenic injury risk.
• Male: The distal ureter runs near the seminal vesicles and vas deferens as it approaches the bladder.

4) Physiologic constrictions (UPJ, iliac crossing, UVJ) with diagram and imaging examples

The ureter has three clinically important physiologic narrowing points where stones commonly lodge and where obstruction is more likely to occur. Learning them as a sequence helps you predict symptoms and imaging findings.

Text diagram: the three narrowing points along the course

Kidney/renal pelvis        Pelvic brim                 Bladder wall
     |                         |                          |
     |  (1) UPJ                | (2) Iliac crossing       | (3) UVJ
     V                         V                          V
  [Renal pelvis]--->|==== ureter ====|--->|==== ureter ====|--->[Bladder]

Imaging examples: how to recognize obstruction at each constriction

Example A: UPJ-level obstruction (CT urography or ultrasound correlation)

• What you look for: Dilated renal pelvis with relatively less distal ureteral dilation early on.
• Reasoning step-by-step: (1) Identify renal pelvis dilation; (2) look for abrupt caliber change at the UPJ; (3) trace ureter distally to confirm it is not dilated to the same degree.

Example B: Iliac vessel crossing stone (non-contrast CT for stone)

• What you look for: Hyperdense focus near the pelvic brim with proximal hydroureter.
• Reasoning step-by-step: (1) Trace ureter down the psoas; (2) find the point where it crosses the iliac vessels; (3) check for a stone and upstream dilation.

Example C: UVJ stone (non-contrast CT or delayed contrast phase)

• What you look for: Stone at the distal ureter near bladder entry; possible mild hydroureter; bladder symptoms may be prominent.
• Reasoning step-by-step: (1) Identify the bladder; (2) locate the expected ureteric orifice region; (3) look just proximal to the bladder wall for a stone; (4) confirm upstream dilation.

5) Surface anatomy cues: visualizing ureters relative to vertebral levels and pelvic landmarks

Core mental model: “posterior abdominal wall to pelvic brim to bladder”

For surface visualization, imagine each ureter as a gently curving line that begins deep in the flank, descends vertically in the abdomen, then angles forward and inward in the pelvis to reach the bladder.

Vertebral and bony landmark cues (practical visualization)

• Upper ureter: Deep to the flank region, descending on the posterior abdominal wall. When mapping on a skeleton model, place it near the lateral aspect of the lumbar vertebral region, then track inferiorly.
• Pelvic brim landmark: The ureter crosses into the pelvis near the iliac vessels at the pelvic brim. On a pelvis model, use the iliac vessel region as the “gateway” point.
• Bladder target: The distal ureter approaches the bladder from posterolateral direction and enters the bladder wall obliquely.

Palpation and pain referral cues (applied anatomy)

Although the ureter itself is not palpable, learners can use typical pain migration patterns to reinforce the course. As a stone moves from upper to lower ureter, pain often shifts from flank toward groin, reflecting the ureter’s descent and pelvic approach.

• Upper ureter irritation: More flank/upper abdominal discomfort.
• Mid-ureter near pelvic brim: Pain can localize lower, sometimes toward the lower abdomen.
• Distal ureter/UVJ: Pain may be felt in the suprapubic region with urinary urgency/frequency.

Quick self-check exercise (no imaging required)

1. On a torso diagram, draw a line from the renal pelvis region down along the psoas (posterior abdominal wall).
2. Mark a point at the pelvic brim where the line crosses the iliac vessels (second constriction).
3. Curve the line anteromedially along the lateral pelvic wall toward the bladder.
4. Mark the bladder entry point (UVJ) as the final constriction.