It is commonly believed that the perirectal space is divided by the lateral rectal ligament into the anterior rectopelvic space and the posterior rectal space, which lies behind the rectum (i.e., the presacral space). Clinicians emphasize the existence of the lateral rectal ligament, but the anatomical elaboration of its morphology, scope, content and structure has not been very clearly defined so far, thus causing confusion among surgeons in clinical surgery, and there is currently no uniform standard for its management. These doubts are mainly focused on three aspects: First, is there a subrectal artery in the lateral rectal ligament? Second, how to deal with the lateral rectal ligament is more reasonable? Third, what is the relationship between the lateral rectal ligament and the rectal mesentery? Therefore, we observe the pelvic anatomy to deepen our understanding of the lateral rectal ligament. 1. Materials and methods 1.1 Study materials Ten voluntarily donated adult cadavers with no pelvic lesions, including seven males and three females, were collected by the Red Cross Society of the Second Military Medical University and provided by the Department of Anatomy and Research of the Second Military Medical University. All specimens were fixed in 10% formalin solution and intra-arterially perfused with red latex solution. 1.2 Sampling and pelvic anatomical exposition The pelvic specimens were taken from the fourth lumbar plane up to the upper 1/3 of the thigh transecting the cadavers. The anterior abdominal wall was excised from the superior border of the pubic symphysis, inguinal ligament, and iliac muscle, and the small intestine and colon above the sigmoid colon were removed to clear the contents of the pelvic and intestinal cavity. Anatomy: identify the bilateral ureters and free the intestinal segment along the junction of the sigmoid mesentery and the lateral wall peritoneum toward the pelvis to the rectal bladder (or uterine) trap; lift the sigmoid colon and gently pull it to the left, and incise it at the root of the mesentery. The submesenteric artery was marked anatomically, dissected at the root, and the intestinal segment was pulled ventrally to reveal the anterior sacral space, which was carefully freed to the sacrorectal ligament. The bladder (uterus) is lifted ventrally, and the peritoneal reflex is opened to reveal the rectal and bladder (uterine) gap, and it is carefully freed distally to the lower edge of the seminal vesicle gland (posterior vaginal wall). 1.3 Exposure of the lateral rectal ligament The anterior lobe of the pelvic peritoneum at the lowest point of clipping is clamped up with vascular forceps, while the anterior bladder or uterine vagina is pulled forward and upward with deep pulling hooks to reveal the tougher Denonvilliers fascia, and the freeing continues anterior to this fascia to reach the seminal vesicles and prostate gland. (When there is difficulty in exposure, the anterior pubic symphysis is removed by clamping, the posterior pubic space is exposed, and the anterior rectal organs are incised in a median sagittal position.) The rectum is retracted ventrally and medially to the pelvic cavity to reveal the structure and connection between the rectum and the lateral pelvic wall. 1.4 Statistical processing The obtained data were statistically processed with spss16.0 software. 2. Results Among all the dissected specimens, lateral rectal ligaments were found on the left and right sides of the pelvis in a total of 20 cases. 2.1 Morphology of the lateral rectal ligament Keeping the rectum in the pelvic cavity without any traction, the rectum was observed in the pelvic cavity. In the pelvic cavity, some tissue structures could be found between the lateral rectal mesentery and the pelvic wall after the anterior-posterior separation of the rectum was completed. By pulling the rectum ventrally and medially, it can be found that the originally loose connection appears as a triangular or trapezoidal structure with the apex or vertex pointing toward the rectum and the bottom edge in the lateral pelvic wall. We recognize this structure as the lateral rectal ligament. In the 20 pelvic conditions observed, the lateral rectal ligament was triangular in 8 cases and trapezoidal in 12 cases. When the lateral rectal ligament was observed from the dorsal side of the rectum, the lateral ligament appeared as a connective tissue structure converging toward its apex. 2.2 Location of the anatomy of the lateral rectal ligament The lateral rectal ligament is located between the lateral posterior aspect of the rectum and the lateral wall of the pelvis, corresponding to the level of the beginning of the sacral 3 vertebral body or the middle vertebral body, and presents a triangular or trapezoidal tissue, with the tip facing the rectum and the bottom edge of the triangle (trapezoid) on the lateral wall of the pelvis. 2.3 Nerves in the lateral rectal ligament The nerve fibers in the lateral rectal ligament form the main contour of the lateral ligament. The nerve fibers are mainly from the rectal branch of the inferior abdominal plexus, the pelvic visceral nerves, and tiny branches of the sympathetic lumbosacral trunk can also be found involved in the lateral rectal ligament. 3, Discussion The original concept of the lateral rectal ligament appeared at the beginning of the 20th century, referring specifically to the vascular sheath composed of connective tissue encircling the inferior rectal artery.Miles presented the depiction of the lateral rectal ligament as a membranous structure between the pelvic wall and the lateral anterior rectum, while in Goligher et al. the lateral rectal ligament originates from the pelvic wall fascia, at the level of sacral 3, and is connected to the lateral posterior rectum [2,3]. In contrast, in Sato’s lateral rectal ligament, the currently known tissue structures related to the middle and lower rectum are included: the inferior rectal artery, the inferior subabdominal plexus and the corresponding connective tissue. The lateral rectal ligament is not only the connection between the rectum and the pelvic wall; the outermost structures of the lateral rectal ligament go to the mural fascia of the pelvis (i.e., the superior pelvic diaphragm fascia on the surface with the anal raphe), and the inferior inferior abdominal plexus divides the entire structure into an inner and an outer part.Sato’s description, although large and comprehensive, goes beyond what is known about the surgical rectal free.Heald describes the lateral rectal ligament as the connection between the rectal mesentery and the plexus, and he considered the central structure of the lateral rectal ligament to be no longer the inferior rectal artery but the nerve tissue originating from the pelvic wall. Since the lateral rectal ligament is revealed after the completion of anterior and posterior rectal freeing, we observed that the lateral rectal ligament is clearly different from the above three states. The posterior rectal freeing is performed along the rectal visceral fascia of the rectal mesenteric surface, down to the surface of the anal raphe, and in this level, it is the dorsal condition of the lateral rectal ligament that can be demonstrated. The anterior freeing of the rectum is performed anterior to the Denonvilliers fascia, which becomes the main fascial component of the anterior aspect of the lateral rectal ligament at this point in time, without severance or other treatment of the Denonvilliers fascia. We believe that the surface fascia of the lateral rectal ligament is a continuation of the subabdominal fascia of the bladder to the Denonvilliers fascia anterior to the rectal mesentery, which is the attachment of the rectal branches of the inferior abdominal plexus into the rectum. Therefore, we believe that the lateral rectal ligament is a composite structure formed by a connective tissue matrix with the participation of pelvic nerve fibers. The nerve fibers in it are mainly the rectal branch of the inferior inferior abdominal plexus, and some of the visceral nerve fibers can be found to join. Based on this understanding of the collateral ligament, we believe that the inferior rectal artery does not enter the rectum through the lateral rectal ligament. Although many clinicians have long believed that “there are subrectal vessels in the lateral rectal ligament.” However, it has been noted that “this often requires only a scissor cut, not a ligation.” This can be understood in two ways: 1) the inferior rectal artery is not always present, and 2) the inferior rectal artery is so small that it does not need to be ligated. From our anatomical observations, neither of these points holds true.1. The presence of the inferior rectal artery was found in 90% of our specimens studied.2. The average diameter of the inferior rectal artery found in our study was more than 1.5 mm, which is in the category of the middle arteries, and it is inconceivable that such an artery would not be ligated during surgery. Care should be taken to protect the nerve fibers when dealing with the lateral rectal ligaments during surgery. Significant nerve fiber tissue can be observed in the lateral rectal ligament. As shown in Figure 3, not only the inferior infra-abdominal plexus is involved in forming the lateral rectal ligament, but also the pelvic visceral nerves and some of the infra-abdominal nerves form the outline of the lateral ligament. The nerves entering the rectum are mainly from the rectal branch of the inferior infra-abdominal plexus. Urinary and sexual dysfunction caused by injury to the inferior abdominal nerve and lower abdominal plexus is a major complication of pelvic surgery, so the lateral rectal ligament should be carefully stripped and excised to protect the associated nerve during surgical procedures related to the lateral rectum. The description of the lateral ligament surgeon is based on the intraoperative view presented, and this triangular structure should be the state of the lateral rectal ligament as seen from the top down. From Figure 2, there is a dilemma of how to sever the lateral rectal ligament while avoiding damage to the nerve plexus. However, if the rectum is pulled toward the ventral side and the lateral rectal ligament is kept under certain tension, it should be possible to sever the lateral ligament without breaking the tether and damaging the main trunk of the inferior inferior abdominal plexus. 4.Conclusion The lateral rectal ligament is not a channel for the inferior rectal artery to enter the rectum, and the composition of the lateral rectal ligament is mainly composed of the nerve and its accompanying connective tissue. Adequate understanding of the composition and structure of the lateral rectal ligament can avoid bleeding and autonomic nerve injury caused by lateral rectal freeing. When performing the middle and lower rectal freeing, the rectum should be pulled forward medially to maintain a certain tension, which helps to avoid the injury of the lower inferior abdominal plexus, thus reducing the occurrence of postoperative complications.