anal columns

The anal valves join together the lower ends of the anal columns.

The anal sinuses (rectal sinuses) are furrows in the anal canal, that separate the anal columns from one another.

In most cases the ileoanal anastomosis lies at the top of the anal columns and hence the anal transition zone is retained; however, in patients with polyposis we usually perform a mucosectomy and a sutured anastomosis at the denate line.

Anal columns (Columns of Morgagni or less commonly Morgagni's columns) are a number of vertical folds, produced by an infolding of the mucous membrane and some of the muscular tissue in the upper half of the lumen of the anal canal.