[Diverticulosis. Anatomical aspects]

Sigmoid diverticula are pseudodiverticula, protrusions of the mucosa between the muscularis, so that they pouch out ball shaped under the serosa or in the fatty connective tissue of the sigmoid region. They occur in pairs, often symmetrically along the taenias. They increase with age; as their evidence depends on the actual contraction of the bowel, the incidence varied strongly with the method of investigation. The pseudo-diverticula can cause diverticulitis. The anatomical characteristics of the large bowel are the fortified longitudinal muscular bands, the taenias, and the haustras. By a contraction and a permanent shortening of the taenias the normally "open" haustras become closed pressure chambers. The muscular coat and the mucosal coat differ very much in size, that the mucosa folds out to the outside. Of decisive importance is, that the muscular and mucosal coat are both fixed to each other by a sliding layer. The modern popular etiological theories can be fairly summarized under the point of view of the longitudinal shortening and the sliding layer.