trigone is a portion of the blank bladder
Trigone of urinary bladder The trigone (a.k.a. vesical trigone)[1] is a smooth triangular region of the internal urinary bladder formed by the two ureteric orifices and the internal urethral orifice.
Urethra In the human female, the urethra is about 1.9 inches (4.8 cm) to 2 inches (5.1 cm) long and exits the body between the clitoris and the vagina, extending from the internal to the external urethral orifice. The meatus is located below the clitoris. It is placed behind the symphysis pubis, embedded in the anterior wall of the vagina, and its direction is obliquely downward and forward; it is slightly curved with the concavity directed forward. The proximal 2/3rds is lined by transitional epithelium cells while distal 1/3rd is lined by stratified squamous epithelium cells.[7]