ureterovesical junction

At the site where each ureter enters the urinary bladder lies a valve-like structure, the ureterovesical junction. Its competence is a matter of geometry rather than of a discrete sphincteric organ: the ureter normally passes through the detrusor muscle at an oblique angle, and that oblique intramural course is what prevents urine from refluxing back up the ureter toward the kidney. When bladder pressure rises, the surrounding detrusor compresses the obliquely traversing segment and closes it. The junction is recorded in Latin as the vesico-ureteral junction and is classified within the urinary system as a valve. Because reflux protection depends on the angle of entry, the junction is described anatomically in terms of that trajectory through the bladder wall.