Cervico‐motor reflex: Description of the reflex and role in sexual acts

A recently identified reflex, termed the “cervico‐motor reflex,” was studied in 15 healthy women (mean age 36.6 years). The response of levator ani (LA) and puborectalis (PR) muscles to electrical and mechanical stimulation of the cervix uteri (CU) was determined. One concentric needle electrode was inserted into the CU (stimulating), a second into the LA (recording), and a third into the PR (recording). The vaginal pressure was measured at rest and on cervical stimulation by balloon‐tipped catheters. Electrical stimulation of the CU led to a reduction in pressure in the upper portion of the vagina (p < .05) and an increase in pressure in the middle and lower portions (p < .001). Stimulation also caused an increase in the electromyographic (EMG) activity of the LA and PR muscles (p < .01). Mechanical stimulation induced the same effects but to a lesser degree. Stimulation of the anesthetized CU, LA, or PR did not evoke the response. The data suggested the presence of a reproducible reflex relationship between the CU and both the LA and PR. During the sexual act and penile buffeting of the CU, levator contraction “balloons” the upper vagina, which acts as a “receptacle” for the semen. Meanwhile, PR contraction narrows the lower vagina, which may effect an increase of penile erection and rigidity. The cervico‐motor reflex may be incorporated as an investigative tool in sexual act disorders.