Objective: To perform an anatomical observation on the extension of the mesocolon to the mesorectum and the continuity of the fasciae lining the abdomen and pelvis, in order to clarify the appropriate surgical plane of total mesorectal excision. Methods: This is an descriptive study. The operation videos of 61 cases (28 males, 33 females, median age of 61) were collected. All the patients underwent laparoscopic colorectal surgery from January 2018 to December 2018 in Yangpu Hospital, including low anterior resection for rectal cancer in 25 cases, left hemicolectomy for descending colon cancer in 15 cases, and subtotal resection of the colon for intractable constipation in 21 cases. Among these 21 constipation patients, 8 received additional modified Duhamel surgeries. Gross anatomy was performed on 24 adult cadavers provided by Department of Anatomy, Shanghai Jiaotong University School of Medicine, including 23 formalin-fixed and 1 fresh cadaver (12 males, 12 females). Sixty-one patients and 24 cadavers had no previous abdominal or pelvic surgical history. The anatomy and extension of fasciae related to descending colon, sigmoid colon and rectum, especially the morphology of Toldt fascia, and the continuities of mesocolon and mesorectum were observed carefully. The distribution characteristics of the fasciae and anatomical landmarks during laparoscopic surgery were recorded and described. Results: The anatomical study on 24 cadavers showed that visceral fascia was the densest connective tissue in the pelvic, posterolateral to the rectum, and stretched as a hammock to lift all pelvic organs. Among 61 patients undergoing laparoscopic surgery, 36 (59.0%) needed to free the left colon during operation, and Toldt fascia in the descending colon segment presented as potential, avascular and extensible loose connective tissue plane between the mesocolon and posterior Gerota fascia; 33 (54.1%) needed to free the rectum during operation, and Toldt fascia extended downward to pelvis as loose connective tissue between the fascia propria of the rectum and visceral fascia; the fascia propria of the rectum exposed completely in 32 (32/33, 97.0%) cases, which ran downward and fused with visceral fascia at the level of the fourth sacral vertebra. The anatomy of 24 cadavers also showed that fascia propria of the rectum fused with visceral fascia at the level of Waldeyer fascia. The fusion line of these two fasciae was supposed to be the extension of Waldeyer fascia. There were two avascular planes behind the rectum: one between the fascia propria of the rectum and visceral fascia, and the other between the visceral fascia and parietal fascia. In 8 constipation cases undergoing laparoscopic subtotal colon resection plus modified Duhamel operation, both mesocolon and mesorectum needed to be mobilized. It was obvious that the mesocolon of descending colon extended and became the mesocolon of sigmoid colon, and ran further into the pelvic and became the mesorectum. The colon fascia of descending colon served as the natural boundary of mesocolon extended downward as the fascia of sigmoid colon and the fascia propria of the rectum, respectively. Toldt fascia locating between mesocolon of descending colon and Gerota fascia extended to pelvis as the 'presacral space' between the fascia propria of the rectum and visceral fascia. Gerota fascia in descending colon segment extended as urogenital fascia in sigmoid colon segment and visceral fascia in the pelvis, respectively. In the cadaver anatomy study, the visceral fascia served as a corridor carrying the hypogastric nerve, and ureter was observed in 23 (23/24, 95.8%) cases. The visceral fascia passed from posterior to anterior lateral of rectum, fusing with Denonvilliers fascia in a fan shape. The pelvic plexus located exactly external to the junction of visceral fascia and Denonvilliers fascia. Pelvic splanchnic nerves went through the parietal fascia toward to the inferolateral of the pelvic plexus. Conclusion: Fascia propria of the rectum and the visceral pelvic fascia are two independent layers of fascia, and the TME surgical plane is between the fascia propria of the rectum and visceral pelvic fascia instead of between the visceral and the parietal pelvic fascia.
目的： 通过研究腹盆腔筋膜以及结肠系膜与直肠系膜的延续性，明确直肠固有筋膜与脏筋膜的关系，探讨全直肠系膜切除术的解剖学平面。 方法： 采用描述性研究方法。回顾性收集2018年1—12月期间于同济大学附属杨浦医院行腹腔镜结直肠手术、且保存有完整手术视频的61例患者资料，其中男28例，女33例，中位年龄61岁，其中因直肠癌行低位前切除术25例，因降结肠癌行左半结肠切除15例，因顽固性便秘行腹腔镜下结肠次全切除术21例，其中8例患者同时行改良Duhamel手术。并解剖观察24具来源于上海交通大学医学院解剖教研室的成人尸体标本;甲醛固定标本23具，新鲜尸体1具；男性12具，女性12具。61例患者和24具尸体既往均无腹、盆腔手术史。仔细观察降结肠、乙状结肠和直肠相关筋膜解剖和走向，特别是Toldt筋膜的走行变化，结肠系膜和直肠系膜的延续性，并对筋膜的分布特点与镜下定位标志进行记录和描述。 结果： 在24具尸体解剖中，脏筋膜都表现为盆腔最为明显的致密的结缔组织，从侧后方托起盆腔脏器，外观呈现为"吊床样"，包围并托起整个盆腔器官。在61例腹腔镜手术患者中，36例（59.0%）的手术过程需要游离左半结肠，Toldt筋膜在降结肠段表现为结肠筋膜与肾前筋膜（Gerota筋膜）之间的潜在的、无血管的、易扩展的疏松结缔组织；33例（54.1%）的手术过程需要游离直肠，术中可见Toldt筋膜向下延伸，在盆腔表现为直肠固有筋膜和脏筋膜之间的疏松结缔组织；32例（32/33，97.0%）的直肠固有筋膜显露完整，向下约在骶4水平处与脏筋膜融合；所有24具尸体解剖也均显示，在Waldeyer筋膜水平处直肠固有筋膜融合于脏筋膜，两者的融合线为Waldeyer筋膜的延伸。直肠后方的两个无血管平面分别为直肠固有筋膜与脏筋膜之间的平面，和脏筋膜与壁筋膜之间的平面。在8例行结肠次全切除+改良Duhamel手术的患者中，需要同时游离结肠和直肠，可以观察到降结肠段的结肠系膜延伸为乙状结肠段的结肠系膜，再向盆腔延伸为直肠系膜；构成降结肠段的结肠筋膜向下依次延伸为乙状结肠筋膜和直肠固有筋膜；降结肠系膜和Gerota筋膜之间的Toldt筋膜向下延伸为直肠固有筋膜与脏筋膜之间的间隙；降结肠段的Gerota筋膜向下延伸为乙状结肠段的尿生殖筋膜，至盆腔为脏筋膜。23具（23/24，95.8%）尸体解剖可以观察到腹下神经走行于脏筋膜内。脏筋膜从后方走向前侧方，并与Denonvilliers筋膜汇合，盆丛位于这个汇合部的外侧，盆内脏神经穿过壁筋膜走向盆丛的外下方。 结论： 直肠固有筋膜和脏筋膜是两层独立的筋膜，全直肠系膜切除的手术平面应位于直肠固有筋膜和脏筋膜之间。.
Keywords: Fascia propria of the rectum; Toldt fascia; Total mesorectal excision; Visceral pelvic fascia.