Abstract: Anatomical study of male pre-rectal space and its clinical application in transanal total mesorectal excision                 GUO Zhen*，ZHANG Yi，ZHANG hao，et al. *Department of Anatomy，Chongqing Medical University，Chongqing 400016，China
Corresponding author：ZHU Shu-juan，E-mail：shujuanzhu@cqmu.edu.cn
Abstract    Objective    To confirm the anatomical level and position marks of pre-rectal space by transanal approach. Methods    Twenty-two adult male pelvic specimens were selected for fine anatomical observation of the location and adjacent structures of the prerectal space in a median sagittal view and under a simulated transanal total mesorectal resection path with 4x magnification; 50 normal adult male pelvic magnetic resonance images were compared and statistically analyzed with the corresponding measurement data of cadaveric specimens, and surgical videos of 25 male rectal cancer patients who underwent taTME in the Department of Gastrointestinal Surgery of the First Affiliated Hospital of Chongqing Medical University from August 2019 to April 2021 were selected for in vivo anatomical observation of important adjoining structures in the prerectal space. Results    The results of autopsy data showed that the distance from the lower border of the prerectal space to the anal verge was approximately 4.6 cm, to the dentate line was approximately 2.8 cm, and the distance from the dentate line to the anal verge was approximately 1.8 cm; the results of magnetic resonance data showed that the distance from the lower border of the prerectal space to the anal verge was approximately 4.8 cm. taTME surgical biopsy observation showed that when the rectal wall incision line was located in the upper area of the plane of the prerectal space, the prerectal space can be entered by cutting the intestinal wall from the inner lumen of the rectum;when the incision line is located in the lower area of the plane of the lower area of the prerectal space, the posterior wall of the prostate can be seen by cutting the intestinal wall at 1 to 2 o'clock in the truncated position or at 10 to 11 o'clock on the opposite side and then the structures such as the rectourethral muscle can be separated from the cranial side to the caudal side against the anterior rectal wall. Conclusion    The plane of the lower boundary of the prerectal space was used to divide the transanal surgical operation into upper and lower zones, and the different accesses helped to enter the prerectal space smoothly and reduce the injury to the urethra and the urethral membrane of the NVB.

Key words: pre-rectal space, rectal cancer, transanal total mesorectal excision, rectourethral muscle, anatomy

摘要： 目的    确认经肛进入直肠前间隙的解剖层次及定位标志。方法    自2020年7月至2021年4月在重庆医科大学人体大体形态学实验室完成。选用成年男性盆部标本22具，在正中矢状切面下模拟经肛全直肠系膜切除（taTME）进行4倍放大做精细解剖观测直肠前间隙的位置和毗邻结构。将50名正常成年男性盆部磁共振数据与尸体标本相应测量数据进行对比分析。回顾性分析2019年8月至2021年4月重庆医科大学附属第一医院胃肠外科收治的行taTME的25例男性病人手术视频，对其直肠前间隙等重要毗邻结构进行解剖学观察。结果    尸体解剖数据结果显示，直肠前间隙下界至肛缘距离约为4.6 cm，距齿状线约为2.8 cm，齿状线至肛缘距离约为1.8 cm；磁共振数据结果显示，直肠前间隙下界至肛缘距离约为4.8 cm。taTME手术视频解剖学观察显示，当直肠壁切开线位于直肠前间隙下界上区，由直肠腔内向外逐层切开前壁即可进入直肠前间隙；当切开线位于直肠前间隙下界下区，由内向外逐层切开直肠前壁时会遇到直肠尿道肌和会阴体等组织结构，此时可采取侧方入路即从截石位的1～2点钟或10～11点钟方向切开肠壁向头侧解剖越过直肠前间隙下界（直肠尿道肌），进一步分离可观察到前列腺后壁被膜进入到直肠前间隙（上区），再从头侧向尾侧方向沿前列腺后壁平面紧贴直肠前壁离断直肠尿道肌等组织结构。结论    以直肠前间隙下界平面将经肛手术操作分为上、下区，经不同入路有助于顺利进入直肠前间隙，减少尿道膜部及神经血管束的损伤。

关键词: 直肠前间隙, 直肠癌, 经肛全直肠系膜切除, 直肠尿道肌, 解剖学