The anal columns, also known as columns of Morgagni are a number of longitudinal folds of the anal mucosa.
The columns unite inferiorly to form crescentic shaped anal valves. Shallow clefts of mucosa are formed in between the columns and valves, termed the anal sinuses. The anal valves form a complete ring around the anal canal, called the dentate (pectinate) line, which marks the position of the embryological anal membrane.
History and etymology
Vertical folds of the distal rectum was first described by Giovanni Battista Morgagni (1682-1771) in his textbook 'De Sedibus et Causis Morborum per Anatomen Indagatis' (On the Seats and Causes of Diseases Investigated by Anatomy) in 1761 3. He is also known for describing the testicular appendix (hydatid of Morgagni) 3.