The area above the anus is the anal canal, which begins at the dentate line and descends to the anal verge, and is 2-3 cm long, covered by the skin, and wrapped on the outside by the internal and external anal sphincters, as well as the anal raphe muscles. There is a white line in the anal canal, which can be palpated during rectal palpation and is the lower edge of the internal anal sphincter. Patients with anal fissures primarily present with cracks in the skin at the anal canal, forming ulcers. Above the anal canal is the rectum, which is 12-15 cm long, and the anterior wall of the rectum is covered by the peritoneum in the middle 1/3 of the area, forming the rectal uterine pit or rectal bladder pit, which is the lowest part of the pelvis. When infection occurs in the abdominal cavity or pelvis, the effusion mostly converges here, with poor absorption ability, not easy to cause systemic toxic symptoms, but prone to pelvic abscess. There is an enlarged pot-belly in the rectum, which can store feces. Rectal tumors are common tumors of the digestive tract, most of which can be palpated through rectal rectal diagnosis.