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.
Ureter In human anatomy, the ureters are tubes made of smooth muscle fibers that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually 25–30 cm (10–12 in) long and around 3–4 mm (0.12–0.16 in) in diameter. Histologically, the ureter is lined by the urothelium, a type of transitional epithelium, and has an additional smooth muscle layer in the more distal one-third to assist with peristalsis.