Ureter

Overview

Paired 25 cm long muscular tubular structures that conduct urine from the renal pelvis to the urinary bladder

Origin

Pelvouretric junction of the kidneys, posterior to the renal vein and artery in the renal hilum.

• The renal pelvis is a funnel-like structure within the hilum of the kidney which receives urine from the major calyces

Course

Abdominal Part

• Descends in the retroperitoneal cavity on the anteromedial aspect of the psoas major, anterior to the tips of the transverse process of the lumbar spine
• Crosses the pelvic brim to enter the pelvic cavity at the bifurcation of the common iliac arteries, anterior to the sacroiliac joints
  • The pelvic brim is the edge of the pelvic inlet – defined by the prominence of the sacrum, the arcuate and pectineal lines, and the upper margin of the pubic symphysis.

Pelvic Part

• Within the pelvic cavity, they travel down the lateral pelvic walls.
• Passes inferomedially to the internal iliac artery to enter the bladder in an oblique angle at the upper corners of the trigone
  • The oblique angle helps create a one-way valve to prevent reflux, where high intramural pressure collapses the ureters

Points of constriction

• Pelvo-ureteric junction
• Crossing of the pelvic brim
• Vesico-ureteric junction

Termination

Terminates at the vesico-ureteric junction at the level of the ischial spine

Arterial Supply

• Abdominal ureter – branches from the renal and gonadal artery, abdominal aorta, and common iliac arteries.
• Pelvic ureter – branches from the vesical and uterine arteries (branches of the anterior division of the internal iliac artery)

Innervations

Innervation for ureteral peristalsis originates from the intrinsic smooth muscular pacemaker sites located in the minor calyces of the renal collecting system.

There is preganglionic sympathetic input from T10 through L2. The aorticorenal, superior, and inferior hypogastric autonomic plexuses give rise to the postganglionic fibers.

S2 through S4 provide parasympathetic innervation to the ureter.

Lymphatics

• The lymphatic drainage is to the internal, external, and common iliac nodes.
• Left ureter primarily drains to the left para-aortic lymph nodes
• Right ureter primarily drains to the right paracaval and interaortocaval lymph nodes

Development

Embryologically, the ureter originates from the ureteric bud, which is a protrusion of the mesonephric duct, a part of the genitourinary system development.

Variants

• Duplex collecting system with single ureter
• Duplex collecting system with double ureter
• Bifid ureter
• Ectopic ureter
• Ureterocele
• Accessory ureter
• Circumcaval ureter