THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -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.

Detailed explanation-2: -[13] The bladder has three openings at the smooth triangular region of the bladder; this is called the trigone. Two of the openings are where the distal portions of the ureters insert, and the other opening is the orifice for the urethra.

Detailed explanation-3: -Urine leaves the bladder via the urethra, a single muscular tube ending in an opening called the urinary meatus, where it exits the body.