THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -Two of the openings are from the ureters and form the base of the trigone. Small flaps of mucosa cover these openings and act as valves that allow urine to enter the bladder but prevent it from backing up from the bladder into the ureters. The third opening, at the apex of the trigone, is the opening into the urethra.

Detailed explanation-2: -The trigone (a.k.a. vesical trigone) is a smooth triangular region of the internal urinary bladder formed by the two ureteric orifices and the internal urethral orifice. Trigone of urinary bladder. Urinary bladder. The interior of bladder.

Detailed explanation-3: -The correct option is D Trigone. Trigone is the smooth triangular region of the internal urinary bladder formed by two urethral orifices (openings) and the internal urethral orifice (opening).

Detailed explanation-4: -A triangular structure, called the trigone, is found on the posterior wall of the urinary bladder. The trigone as three openings: on the right, the right ureteral opening, on the left, the left ureteral opening, and inferiorly, the internal urethral orifice leading to the urethra.