Takeaway A skin tag is a noncancerous growth of excess skin. Skin tags that form around the anus or rectum are called anal skin tags. Anal skin tags are typically small, measuring a few millimeters or less. They may be the same color as the skin or slightly darker.
Structure[ edit ] In humans, the anal canal is approximately 2. It is surrounded by inner involuntary and outer voluntary sphincters which keep the lumen closed in the form of an anteroposterior slit. The canal is differentiated from the rectum by a transition along the internal surface from endodermal to skin-like ectodermal tissue. Anal canal is traditionally divided into two segments, upper and lower, separated by the pectinate line also known as the dentate line : upper zone zona columnaris mucosa is lined by simple columnar epithelium features longitudinal folds or elevations of tunica mucosa which are joined together inferiorly by folds of mucous membrane known as anal valves supplied by the superior rectal artery a branch of the inferior mesenteric artery lower zone zona hemorrhagica - lined by stratified squamous non-keratinized epithelium zona cutanea - lined stratified squamous keratinized epithelium, which blends with the surrounding perianal skin supplied by the inferior rectal artery a branch of the internal pudendal artery The anal verge referes to the distal end of the anal canal, a transitional zone between the epithelium of the anal canal and the perianal skin. It should not be confused with the pectinate line between the upper and lower zones within the anal canal. Anal gland secretes lymphal discharge and built up fecal matter from the colon lining.