Shafik A, El-Sibai O
Department of Surgery and Experimental Research, Cairo University, Cairo, Egypt.
Urology. 2001 Aug;58(2):193-7. doi: 10.1016/s0090-4295(01)01196-7.
To investigate the effect of levator ani muscle (LAM) (the main muscle in the pelvic floor) contraction on the anorectal and urethrovesical pressures and elucidate its role in the mechanisms of defecation and urination.
In 18 healthy volunteers (10 men and 8 women; mean age 38.6 +/- 10.2 years), the LAM was stimulated to contract by a concentric needle electrode, and the anal, rectal, urethral, and vesical pressure responses were recorded. The test was repeated once after LAM anesthetization with Xylocaine injection and again after saline instead of Xylocaine injection into the LAM.
On LAM stimulation, the anal and urethral pressures had a significant decline (both P <0.05), and the rectal and vesical pressures exhibited no significant changes (both P >0.05). The anal, rectal, urethral, and vesical pressures did not show significant changes on stimulation of the anesthetized LAM; after saline injection, the pressure response was similar to that before injection (P >0.05). These results were reproducible.
LAM contraction lowers the anal and urethral pressures and appears to assist in the evacuation process. We therefore propose that the LAM is a muscle of evacuation and that LAM dysfunction could lead to defecation and urination disorders.
研究肛提肌（盆底主要肌肉）收缩对肛门直肠及尿道膀胱压力的影响，并阐明其在排便和排尿机制中的作用。
对18名健康志愿者（10名男性和8名女性；平均年龄38.6±10.2岁），用同心针电极刺激肛提肌使其收缩，并记录肛门、直肠、尿道及膀胱的压力反应。在向肛提肌注射利多卡因使其麻醉后重复该试验一次，再向肛提肌注射生理盐水而非利多卡因后再次重复试验。
刺激肛提肌时，肛门和尿道压力显著下降（均P<0.05），直肠和膀胱压力无显著变化（均P>0.05）。刺激麻醉后的肛提肌时，肛门、直肠、尿道及膀胱压力无显著变化；注射生理盐水后，压力反应与注射前相似（P>0.05）。这些结果可重复。
肛提肌收缩可降低肛门和尿道压力，似乎有助于排空过程。因此，我们提出肛提肌是一块参与排空的肌肉，肛提肌功能障碍可能导致排便和排尿障碍。
