Applied Anatomy Of Male Pelvic Floor Cloacal Organs And Their Common Mesentery

Objective: In this study,the male pelvic floor cloacal organs and their common mesentery were observed and studied by dissecting human pelvic specimens,so as to provide applied anatomical guidance for lateral lymph node dissection(laterallymphnodedissection,LLND)and low rectal cancer surgery.Methods: Ten adult male cadavers provided by the Department of Anatomy,Department of Medicine,Xi’an Jiaotong University were amputated along the level of the intervertebral disc between the 3rd and 4th lumbar vertebrae and at the junction of the upper and middle thigh.A total of 20 sagittal semi-pelvic specimens were obtained.The male pelvic floor cloacal organs and their common mesentery were dissected and observed by sagittal semi-pelvic approach.Results: the ventral transverse fascia extended inward into the psoas major fascia,the parietal layer of the urogenital fascia(UGF)continued with the psoas major fascia in front of the aorta and the lateral side of the lumbar vertebra,while the visceral layer of UGF entered the mesenteric inherent fascia from the front of the aorta,and the nerves in the UGF entered the mesenteric fascia in front of the aorta,and the mesenteries on both sides were attached to the front of the aorta.UGF enters the pelvic cavity on the surface of the iliac vessels and becomes the anterior fascia of the inferior abdominal nerve.The UGF wall layer extends behind the iliac vessels.Dissecting the anterior fascia of the inferior abdominal nerve,it is found that it is a two-layer structure,which continues with the visceral wall layer of UGF,and the inferior abdominal nerve runs between the two layers of the anterior fascia of the inferior abdominal nerve.No typical "Y" type Denonvilliers fascia was found in a male cadaver.The parietal layer of UGF folds each other to form a twolayer structure around the visceral layer,which is band-like,which contains various vascular and nerve bundles to the cloacal organs.There is a gap between the two layers of UGF,which can be freed,and the parietal layer reaches the lowest position of the rectum,and the visceral layer is reflexed at the fourth sacral ring,passing through the visceral layer and entering the second space.The blood vessels in the lateral direction of the rectum are in the mesenteric bundle.Cut open the mesentery,you can see the branches from the internal iliac artery and the pelvic plexus enter the rectum from the side,and cut off the vascular and nerve bundles to reach the lowest position of the rectum.The vascular and nerve bundles from the lower rectum,prostate,seminal vesicle,bladder,iliac vessels and pelvic plexus to the corresponding organs were removed and observed.UGF wrapped the vascular and nerve bundles from the anterior and posterior sides into its anterior and posterior capsule,and it was found that it was a Mesangial structure in morphology.Conclusion:1.If the cloacal organs(lower rectum,prostate,seminal vesicle gland and bladder)are regarded as a continuous whole,then there is a common Mesangial structure in the pelvic direction,and the visceral wall layer of the genitourinary fascia is covered by these organs.the branches from the internal iliac artery and the pelvic plexus run through them,forming corresponding vascular and nerve bundles into each cloacal organ,thus forming a mesenterylike structure.It contains blood vessels,nerves,lymph and adipose tissue.2.The Denonvilliers fascia is formed by the peritoneum.No typical "Y" structure of Denonvilliers fascia was found in a male cadaver.In the process of peritoneal formation,two layers of peritoneum were pushed together to form Denonvilliers fascia,which further confirmed that Denonvilliers fascia was formed by peritoneum.3.In the operation of low rectal cancer,after dissociating from the anterior and posterior plane of the rectum,surgeons should,on the basis of protecting the pelvic wall nerve plexus,cut off the lateral mesorectum along the contours of the pelvic wall,the proper fascia of the rectum and the extension line of the upper and lower contours of the rectum,and dissociate the rectum from the pelvic wall completely,which can obviously accelerate the speed of the operation and improve the safety of the operation.For LLND,if entering the pelvic direction from the Retzius space,the wall side of the mesentery of cloacal organs can be completely exposed,which is a better and safer surgical approach.4.During the total pelvic organ resection,the Retzius space is used as the surgical approach,the fascia space around the cloacal organ is carefully separated,and the vascular and nerve bundles in the common mesentery and the supporting structure of the organ are cut off along the pelvic wall as a whole,so that the whole pelvic organ can be dissociated.