The urinary bladder is a hollow, muscular organ located in the pelvic cavity. It has several layers including an outer serous membrane, adventitia connective tissue layer, muscularis layer of detrusor smooth muscle, submucosa layer, and inner transitional epithelial lining. As the bladder fills with urine, the lining folds flatten to allow increased storage capacity. The muscularis layer allows the bladder to expand and contract and forms the internal urethral sphincter to hold urine inside.

2. Structure
 It is a hollow, muscular, collapsible bag.
 It is spherical in shape.
 Also known as the body’s urine storage tank.
 Located in the pelvic cavity, behind the pubic
symphysis and anterior to the rectum.
 In women the bladder lies anterior to the vagina and
in front the uterus
 In men it rests on the prostate.

3.  The urinary bladder is made up of several distinct
tissue layers.
 The outer most superior layer of the bladder is made
of serous membrane continuous with the peritoneum.
 The serous membrane provides protection to the
bladder from friction between organs in the
abdominopelvic cavity.
 The surface of the lateral and inferior sides of the
bladder forms a layer of loose connective tissue called
the adventitia.
 The adventitia loosely connects the urinary bladder to
the surrounding tissue of the pelvis.

4.  The walls of the bladder is made mostly of smooth
muscle tissue called the detrusor muscle.
 The detrusor muscle is a layer of smooth muscle
fibers arranged in spiral, longitudinal, and circular
bundles.
 Mucous transitional epithelium that forms folds called
rugae lines the bladder and protects the underlying
tissues from acidic and alkaline urine.
 Surrounding the mucosa layers is the submucosa, a
layer of connective tissue with blood vessels and
nervous tissue

5.  As urine accumulates, the rugae flattens, the wall of
the bladder thins as it stretches, allowing the bladder
to store larger amounts of urine without a significant
rise in internal pressure.

7.  The visceral muscles of the muscularis layer surround
the submucosa and provide the urinary bladder with
its ability to expand and contract.
 The muscularis also forms the internal urethral
sphincter which is a ring of muscle that surrounds the
urethral opening and holds urine in the urinary
bladder.
 During urination the sphincter relaxes to allow urine
to flow into the urethra.

8.  There are three openings in the floor of the bladder.
 Two from the ureters and one into the urethra.
 The ureter openings lie at the posterior corners of the
triangle shaped floor called the trigone.

9. Functions Of The Bladder
 Storage vessel for urine to delay frequency of
urination.
 Collects urine excreted by the kidneys before disposal
by urination.