<P> The three openings, two ureteric orifices, and the internal urethral orifice mark the triangular area called the trigone of the bladder . These openings have mucosal flaps in front of them that act as valves in preventing the backflow of urine into the ureters, known as vesicoureteral reflux . Between the two ureteric openings is a raised area of tissue called the interureteric crest . This makes the upper boundary of the trigone . The trigone is a smooth - muscle area that forms the floor of the bladder above the urethra . It is an area of smooth tissue for the easy flow of urine into and from this part of the bladder - in contrast to the irregular surface formed by the rugae . </P> <P> In men, the prostate gland lies outside the opening for the urethra . The middle lobe of the prostate causes an elevation in the mucous membrane behind the internal urethral orifice called the uvula of urinary bladder . The uvula can enlarge when the prostate becomes enlarged . </P> <P> The bladder is situated below the peritoneal cavity near the pelvic floor and behind the pubic symphysis . In men, it lies in front of the rectum, separated by the recto - vesical pouch, and is supported by fibres of the levator ani and of the prostate gland . In women, it lies in front of the uterus, separated by the vesico - uterine pouch, and is supported by the elevator ani and the upper part of the vagina . The wall of the urinary bladder is normally 3--5 mm thick . When well distended, the wall is normally less than 3 mm . </P> <P> The inner walls have a series of ridges, thick mucosal folds known as rugae that allow for the expansion of the bladder . </P>

Where is the urinary bladder located in females