The neurological organization of micturition

The role of the lower urinary tract (LUT) is to act as a reservoir for urine at low pressures and to empty at appropriate times. In health the bladder becomes gradually filled during the storage phase, and afferent pathways convey signals of bladder fullness. When deemed to be a socially appropriate time and place, there is a switch from the storage phase to the voiding phase. Voiding, which involves co-ordinated activity between detrusor contraction and urethral sphincter relaxation occurs until the bladder is empty. The level of co-ordinated activity is complex, requiring both voluntary and autonomic control. In health, the control of LUT activity is achieved at several levels involving the peripheral nerves, spinal cord and cerebral cortex. The pathway becomes damaged following neurological disease resulting in LUT dysfunction. This chapter outlines the neural organization and control of micturition and the consequences of neurological disease.