QS Study

The urinary bladder is a muscular reservior of urine which lies in the anterior part of the pelvic cavity. Its primary function is as a reservoir for urine. It is an organ that serves to accumulate urine to be voided through urination after the urine is filtered through the kidneys.

Interior of the urinary bladder

In an empty bladder, the greater part of the mucosa shows irregular folds due to its loose attachment to the muscular coat.

In a small triangular area over the lower part of the base of the bladder, the mucosa is smooth due to its firm attachment to the muscular coat. Surrounding the mucosal layer is the submucosa, a layer of connective tissue with blood vessels and nervous tissue that supports and controls the surrounding tissue layers. This area is known as the trigone of the bladder. The size and shape of the urinary bladder change based on the amount of pee it includes. The triangle-shaped base of the bladder, known as the trigone, helps prevent stretching of the urethra or backflow into the ureters. When signaled, the bladder releases urine through the urethra, the tube that carries urine out of the body. In women, this tube ends between the clitoris and the vagina. The urinary bladder is tetrahedral in shape when empty and oval in shape when distended.

Fig: Interior of Urinary Bladder

The apex of the trigone is directed downwards and forwards. The internal urethral orifice is located here. The ureters open at the posterolateral alleles of the trigone. Their openings are 2.5cm apart in the empty bladder and 5cm apart in a distended bladder. A slight elevation on the trigone immediately posterior to the urethral orifice is called the uvula vesicae. The base of the trigone is formed by the interureteric ridge produced by the continuation of the inner longitudinal muscle coats of the two ureters. The ridge extends beyond the ureteric openings as the ureteric folds over the interstitial parts of the ureters.