Effect of micturition on clitoris and cavernosus muscles: an electromyographic study.

We investigated the hypothesis that passage of urine through urethra stimulates corporal tissue and cavernosus muscles. Electromyographic (EMG) activity of corpora cavernosa (CC), bulbocavernosus muscle (BCM), and ischiocavernosus muscle (ICM) was recorded in 27 healthy women before and during micturition. These tests were repeated after individual anesthetization of urethra, corporal tissue, and cavernosus muscles. During micturition, slow wave variables of CC decreased and motor unit action potentials of the BCM and ICM increased. These EMG changes returned to basal values on micturition interruption or termination. Micturition after individual anesthetization of the urethra, corporal tissue, and cavernosus muscles did not effect significant changes in these structures. Decreased EMG activity of CC and increased activity of cavernosus muscles during micturition apparently denotes corporal tissue relaxation and cavernosus muscles' contraction. The latter two actions occurring on micturition are suggested to be mediated through a reflex called "urethro-corporocavernosal reflex" and effect a mild degree of clitoral tumescence.