Aronson M P, Lee R A, Berquist T H
Section of Gynecologic Surgery, Mayo Clinic, Rochester, Minnesota.
Obstet Gynecol. 1990 Nov;76(5 Pt 1):846-51. doi: 10.1097/00006250-199011000-00025.
Five anally continent nulliparas of reproductive age were studied with magnetic resonance imaging. The internal and external anal sphincters could be easily delineated, as could the intervening longitudinal musculature, puborectalis muscle, anococcygeal raphe, anorectal lumen, vagina, uterus, bladder, urethra, coccyx, and pubis. The shape of the sphincters was nearly cylindrical, with an anterior component averaging 18.3 mm thick and 28.0 mm long. Fifty-four percent of this anterior thickness was attributable to the internal sphincter. The anorectal angle varied considerably, with a mean of 86.8 +/- 19.1 degrees (range 60-112). The angle between the portion of the rectal lumen supported by the anococcygeal raphe, or levator plate, and the plane of the puborectalis muscle was consistent at 149.0 +/- 6.3 degrees (138-154). The finding of anterior anal sphincters with substantial thickness and length contrasts markedly with a view often pictured in the literature of a female anal sphincter that narrows anteriorly to half its posterior length and forms a small bundle of muscle rather than a broad band. Knowledge of these relationships is important in primary repair of obstetric sphincter lacerations as well as in surgical correction of anal incontinence.
对5名处于生育年龄、肛门节制功能正常的未产妇进行了磁共振成像研究。肛门内、外括约肌以及其间的纵向肌肉组织、耻骨直肠肌、肛门尾骨缝、肛管直肠腔、阴道、子宫、膀胱、尿道、尾骨和耻骨均能清晰显示。括约肌的形状近乎圆柱形，前部平均厚度为18.3毫米，长度为28.0毫米。前部厚度的54%归因于内括约肌。肛管直肠角变化很大，平均为86.8±19.1度（范围60 - 112度）。由肛门尾骨缝或提肌板支撑的直肠腔部分与耻骨直肠肌平面之间的夹角恒定为149.0±6.3度（138 - 154度）。前部肛门括约肌具有相当厚度和长度这一发现，与文献中常描绘的女性肛门括约肌图像形成了显著对比，文献中的图像显示其前部变窄至后部长度的一半，形成一小束肌肉而非宽带状。了解这些关系对于产科括约肌撕裂伤的一期修复以及肛门失禁的手术矫正非常重要。
