Urineleider

Urineleider, or ureter, is a pair of muscular tubes that transport urine from the kidneys to the urinary bladder. There are two ureters, one on each side of the body.

Each ureter is about 25–30 cm long and runs retroperitoneally along the posterior abdominal wall. It begins at the renal pelvis near the kidney hilum, descends along the psoas major, crosses the pelvic brim, and enters the bladder at the posterolateral wall. Its terminal portion pierces the bladder wall obliquely, creating a one-way valve that helps prevent vesicoureteral reflux during bladder filling.

Structure and movement: The ureter wall has mucosa of transitional epithelium, a submucosa, a muscularis layer formed by an inner longitudinal and an outer circular layer, and an outer adventitia. The smooth muscle generates peristaltic waves that propel urine from the kidney toward the bladder, coordinated in response to urine flow.

Blood supply, innervation and drainage: The ureter receives arterial blood from multiple sources along its length—upper parts from renal and other aorta-derived branches, middle parts from gonadal and common iliac arteries, and lower parts from internal iliac branches. Venous drainage mirrors the arterial supply into the renal and iliac venous systems. Autonomic nerves provide sympathetic and parasympathetic innervation.

Development and clinical relevance: The ureters develop from the ureteric buds of the embryonic mesonephros. Clinically relevant conditions include ureteral stones causing flank pain and hydronephrosis, ureteral strictures, or tumors that obstruct flow. Diagnosis commonly uses CT urography or ultrasound; treatment may involve analgesia, stenting, or surgical repair.