肛提肌垂直部的磁共振成像解剖

摘要

目的:澄清对肛提肌垂直部解剖认识上的错误并显示其正常解剖.方法:运用体线圈磁共振成像技术,获取60例正常志愿者(男、女各30例,年龄19～25岁)仰卧位时肛区的矢状面、冠状面和4个特定斜横断面的T1加权图像,对图像进行分析.结果:肛提肌分横行部和垂直部.在矢状面和冠状面,横行部急转直下形成垂直部;垂直部走行于肛门平滑肌和肛门外括约肌之间,终止于括约肌间沟.在耻骨直肠肌平面,垂直部具有扁平肌肌腹的形态特征,位于裂孔内器官和耻骨直肠肌之间.在外括约肌深部平面,垂直部分叉为左、右两个肌腹样结构.在外括约肌浅部和皮下部平面,即肛管的中下部,垂直部延续为20余个索条样结构.结论:肛提肌垂直部实际是存在的,其末端具有腱索的形态特征.%Objective: To clarify the anatomical understanding error of the vertical portion (VP) of the levator ani muscle and display its normal anatomy.Methods: T1-weighted images of the sagittal section, coronal section and four special cross sections of the anal region were obtained and analysed with a body coil in 60 normal volunteers (30 males, 30 females, aged 1925 years) in anal-sagittal and anal-coronal sections.Results: The muscle bundle of the transverse portion (TP) sloped sharply downward to form the VP, and the VP lied between the anal smooth muscle and the exterral anal sphincter and ended at the intersphincteric groove.On the puborectalis plane, the VP lied between the intrahiatal organs and the puborectalis and had a morphological characteristic of flat muscle belly.On the deep sphincter plane, the VP spread into bilateral muscle bellies.On the planes of the superficial and subcutaneous sphincter, namely the middle-and lower anal canal, the VP changed into more than 20 strip-like structures.Conclusion: The VP of levator ani muscle actually exists and its terminal has a morphological characteristic of tendinous cord.