Urethral sensation: basic mechanisms and clinical expressions.

A prerequisite for conscious bladder control is adequate sensory input to the central nervous system, and it is well established that changes in sensory mechanisms can give rise to disturbances in bladder function. Impulses related to the desire to void are believed to course through the pelvic nerves, and those for sensation of a full bladder course through the pudendal nerves. The sense of imminent micturition most probably resides in the urethra, and the desire to void comes from stretching the bladder wall. In addition, a variety of structures play an important role in terms of urethral closure (such as the urethral epithelium, vasculature and smooth muscle) that are necessary to maintain continence. This overview will discuss mechanisms related in part to the urethra involved in activation of bladder reflexes and sensation with a discussion on the mucosa (urothelium and underlying lamina propria) and underlying cellular structures.