The ureters are bilateral thin (3 to 4 mm) tubular structures that connect the kidneys to the urinary bladder, transporting urine from the renal pelvis into the bladder. The muscular layers are responsible for the peristaltic activity that the ureter uses to move the urine from the kidneys to the bladder.
Embryologically, the ureter originates from the ureteric bud, which is a protrusion of the mesonephric duct, a part of the genitourinary system development.
The ureters begin at the ureteropelvic junction (UPJ) of the kidneys, which lie posteriorly to the renal vein and artery in the hilum. The ureters then travel inferiorly inside the abdominal cavity. They pass over (anterior to) the psoas muscle and enter the bladder on the posterior bladder aspect in the trigone.
Three areas along the path of the ureter are clinically significant for renal stones lodging. These areas are: the ureteropelvic junction (UPJ), the ureterovesical junction (UVJ), and the crossover of the common iliac arteries. The UPJ is where the pelvis of the kidney transitions into the ureter and the UVJ is where the ureters enter the bladder.
The blood supply to the ureter is segmental. The upper ureter closest to the kidneys receives blood directly from the renal arteries. The middle part is supplied by the common iliac arteries, branches from the abdominal aorta, and the gonadal arteries. The most distal part of the ureter receives blood from branches of the internal iliac artery.
T12 through L2 provide innervation to the ureters, creating a ureteric plexus. Pain may refer to T12-L2 dermatomes.
Due to its location, the ureter can be damaged in colon and rectal surgery and gynecologic surgeries.