Pathophysiology of Haemorrhoids and the Consequences for Surgical Treatment

The anal canal is the terminal portion of the intestinal tract. It plays an important role in maintaining faecal continence. It is surrounded by strong sphincters and, due to the tonic contraction of these muscles, it is completely collapsed at rest and represents an antero-posterior slit. The proximal anal canal is covered with anal mucosa that contains an abundance of nerve endings responsible for fine sensory discrimination. This is called the anal sensation. The so-called rectal sensation is located in the pelvic floor muscle. The rectal mucosa itself does not contain receptors and is insensitive to stimuli. Rectal sensation is important to give awareness of the arrival of material in the rectum, whereas anal canal sensation may contribute to the discrimination of the nature of the material.