目的　以直肠中下段为中心解剖观察其毗邻结构，为临床经肛门切除直肠提供解剖学导向。  方法　 结合28例成人盆部CT扫描资料，对14具成人盆部标本进行解剖观察，用游标卡尺测量直肠阴道（尿道）隔的厚度和肛门括约肌及肛提肌的宽度和厚度，结果进行统计学分析。  结果　直肠中下段及肛管毗邻的诸多肌性部分均分别有自己的筋膜包绕，结构易于辨认；在盆部标本和盆部CT扫描片上，测得直肠尿道隔的厚度分别为（1.65±0.19）cm和（1.26±0.05）cm、直肠阴道隔的厚度分别为（0.89±　0.11）cm和（0.75±0.04）cm，在不同材料间的测得值差异有统计学意义（P＜0.05），而该结构的厚度在性别间差异有显著性（P＜0.01），直肠尿道隔的厚度大于直肠阴道隔的厚度。  结论　直肠下段毗邻结构复杂，特别是直肠阴道隔菲薄，应避免手术操作中引起的损伤。

Objective　To provide the guidance for transanal rectal resection through anatomic observation with the center of lower rectum.　Methods　The rectal adjacent structures were observed and the width and thickness of anus sphincter were measured, and then the thickness of recto-vaginal gap and recto-urethra gap were measured and recorded on 14 basin specimens and the film of basin CT scan in 28 adults which were selected from the material without pelvic diseases. The data were compared among different measuring ways and sexes and analyzed with t-Test statistically.　Results　There were many muscular structures surrounded the lower rectum and anus, and every muscule with fascia bandle itself could be recognized easily. The measured values of recto-urethra gap on basin specimens and CT films were（1.65±0.19）cm and （1.26±0.05）cm ,and the values of recto-vaginal gap were（0.89±0.11）cm and（0.75±0.04）cm respectively. It was larger in basin specimens than that in CT films and also larger the values of recto-urethra gap in males than that of recto-vaginal gap in females with significant statistical differences (P< 0.05).　Conclusions　Recognition the structures carefully and keeping the anatomic plane are necessary for avoiding invase injury, because of complicated adjacent structure around the lower rectum and thining recto-vaginal septum.