The pelvic anatomy (obviously) differs greatly in males and females. In males, knowledge of the course of the urethra, especially as it passes through the prostate gland, is of prime importance. In females, it can be difficult to find the external urethral orifice, and precise knowledge of the anatomy is essential.

Urethra

Male | Female

 

Male

The male urethra is longer than the female's and is separated into three parts: prostatic, membranous, and penile. The urethra extends from the bladder to the end of the penis. The prostatic portion of the urethra is the widest and runs through the prostate. The membranous is the shortest and least dilatable. It runs from the prostate to approximately the urogenital diaphragm, where it joins the penile portion. The penile urethra extends through the penis to the urethral meatus.

   

Female

The female urethra is approximately 4 cm long and is embedded in the anterior wall of the vagina. Its external orifice is found just anterior to the vaginal introitus and about posterior to the clitoris.

Bladder

The bladder stores urine and is comprised of the detrusor muscles and other tissues. The physiologic bladder capacity ranges between 400 and 500 ml. Sympathetic innervation and parasympathetic inhibition allow for relaxation of the detrusor muscles so that the bladder can fill with and store urine. Simultaneously, closure of the bladder neck (also mediated by sympathetic innervation and parasympathetic inhibition) ensures that urine does not exit the bladder as it fills.

 

When the bladder is empty it is located within the pelvis but as it fills its superior portion extends into the abdominal cavity.

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