Study of the effect of cervix uteri buffeting on the vaginal musculature with identification of the cervico-vaginal inhibitory reflex

Abstract

During penile thrusting, the penis repeatedly buffets the cervix uteri (CU). We investigated the hypothesis that CU stimulation induces a change in the motor activity of the vaginal wall musculature. The response of the vaginal wall musculature to electrical and mechanical CU stimulation was recorded in 27 healthy women (age 34.8+/-7.3 years). The test was repeated after separate anesthetization of CU and vagina and after normal saline injection. Resting electric activity in the form of slow waves (SWs), followed or superimposed by action potentials (APs), was recorded from two electrodes applied to the vagina. The waves displayed the same frequency, amplitude and conduction velocity from the two electrodes. Electrical or mechanical stimulation of the CU effected disappearance of the electric waves; this response was reproducible. Individual stimulation of the anesthetized CU or vagina did not evoke the response, but saline infiltration did. CU stimulation resulted in disappearance of the vaginal electric activity which presumably denotes vaginal tone disappearance. Meanwhile, stimulation of the anesthetized CU or vagina did not evoke that response. The data suggested the presence of a reproducible reflex relationship between the CU and vaginal musculature that seems to be mediated through a reflex which we call "cervico-vaginal inhibitory reflex". Disappearance of the vaginal tone probably enhances vaginal penetration and penile thrusting during the sexual act and penile buffeting of the CU. The cervico-vaginal reflex may be incorporated as an investigative tool in sexual act disorders.