The cavernoso-anal reflex: response of the anal sphincters to cavernosus muscles' stimulation.
OBJECTIVE
To prove the hypothesis that cavernosus muscles' contraction during coitus affects the reflex contraction of anal sphincters.


METHODS
Electromyographic response of external and internal anal sphincters to ischiocavernosus and bulbocavernosus muscle stimulation was studied in 17 healthy volunteers (10 men, 7 women, mean aged 38.3+/-11.6 years). The test was repeated after individual anesthetization of anal sphincters and the two cavernosus muscles, and after using saline instead of lidocaine.


RESULTS
Upon stimulation of each of the two cavernosus muscles, external and internal anal sphincters recorded increased electromyographic activity. Anal sphincters did not respond to stimulation of the anesthetized cavernosus muscles nor did anesthetized anal sphincters respond to cavernosus muscles' stimulation. Saline infiltration did not affect anal sphincteric response to cavernosal muscles' stimulation.


CONCLUSIONS
Cavernosus muscles' contraction is suggested to evoke anal sphincteric contraction, which seems to be a reflex and mediated through the "Cavernoso-anal reflex". Anal sphincteric contraction during coitus presumably acts to close the anal canal to thwart flatus or fecal leak.
Shafik
Ahmed
A
Department of Surgery and Experimental Research, Faculty of Medicine, Cairo University, 2 Talaat Harb Street, Cairo 11121, Egypt. shafik@ahmedshafik.com
Shafik
Ismail
I
Shafik
Ali A
AA
El Sibai
Olfat
O
D000328:Adult; D001003:Anal Canal / Q000502:physiology*; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D012016:Reference Values; D012018:Reflex / Q000502:physiology*