Urogenitodynamics of the male bladder neck. 1. During continence

The dynamic behavior of the male bladder neck during urinary continence was studied by electromyography in dogs and rabbits. On vesical filling, increased electrical activity in the form of biphasic potentials was recorded from the anterolateral segment of the bladder neck. These biphasic potentials became more frequent and higher in voltage with further filling of the bladder. Concurrently, the posterior segment showed no significant electromyographic changes. These findings indicate muscular contraction of only the anterolateral part of the bladder neck during vesical filling. We conclude that the sphincteric function of the bladder neck during urinary continence is achieved by the active muscular contraction of its anterolateral segment. We postulate that the posterior segment is mainly concerned with the genital function of the bladder neck.