title: Anorectal closing mechanisms.
abstract: The thrust of this contribution is contained in an analysis of the refined sealing devices which supplement the co-operative interactions between the anorectum and its surroundings. They include an active smooth-muscle complex which, with elastic tissue, is closely related to vascular anal cushions. These, when distended, plug the anal lumen and complete continence. Additional objectives are: (i) to draw attention to new concepts on the nature of haemorrhoids; (ii) to add illustrations to support the idea of tripartite sealing plugs in the form of anal "cushions"; (iii) to note discrepancies in the literature on the exact siting of the pectinate/dentate line in the anal canal which have a bearing on the theory of the anal cushion; (iv) to give reasons why the musculus submucosae ani should not be termed Treitz's muscle; (v) to review some morphological, pressure, motility and electromyographic sutdies of the neuromusculature of the anorectal region in normal subjects and in patients with haemorrhoids; and (vi) to add explanations and suggestions to fit the concept of the anal cushion into a broader framework of use to the surgeon.
mesh_terms: D000328:Adult; D000368:Aged; D001003:Anal Canal / Q000473:pathology / Q000503:physiopathology*; D004576:Electromyography; D005260:Female; D006484:Hemorrhoids / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D007223:Infant; D007413:Intestinal Mucosa / Q000473:pathology; D009130:Muscle, Smooth / Q000473:pathology / Q000503:physiopathology; D011312:Pressure; D012007:Rectum / Q000503:physiopathology*