Shafik Ahmed, Shafik Ismail, Shafik Ali A, El Sibai Olfat
Department of Surgery and Experimental Research, Faculty of Medicine, Cairo University, 2 Talaat Harb Street, Cairo 11121, Egypt.
Asian J Androl. 2006 May;8(3):331-6. doi: 10.1111/j.1745-7262.2006.00126.x.
To prove the hypothesis that cavernosus muscles' contraction during coitus affects the reflex contraction of anal sphincters.
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.
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.
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.
验证性交时海绵体肌收缩影响肛门括约肌反射性收缩这一假说。
对17名健康志愿者（10名男性，7名女性，平均年龄38.3±11.6岁）研究肛门外括约肌和内括约肌对坐骨海绵体肌和球海绵体肌刺激的肌电图反应。在分别对肛门括约肌和两块海绵体肌进行麻醉后，以及使用生理盐水代替利多卡因后重复该试验。
刺激两块海绵体肌中的任何一块时，肛门外括约肌和内括约肌的肌电图活动均增强。麻醉后的海绵体肌刺激未引起肛门括约肌反应，麻醉后的肛门括约肌对海绵体肌刺激也无反应。生理盐水浸润不影响肛门括约肌对海绵体肌刺激的反应。
提示海绵体肌收缩可诱发肛门括约肌收缩，这似乎是一种反射，通过“海绵体-肛门反射”介导。性交时肛门括约肌收缩可能起到关闭肛管以防止排气或粪便泄漏的作用。
