An anatomico physiological principle governing the direction of the gastro intestinal mucosal folds during life
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The mucosa, being the innermost layer of the gastro intestinal tract, is intimately concerned with digestion and absorption, and, presumably, also with the transport of intestinal contents. In anatomical, physiological and motility studies, possible movements of the mucosa and its folds are neither considered nor investigated. Dogmatic statements about the direction of the folds are often made. Radiologists have long been aware of mucosal movements, but after the fundamental work of Forssell, no further views have been put forward. Radiological procedures have been used to investigate the normal, macroscopic, physiological movements of mucosal folds. A general rule follows. Normally, when the intestine is filled, but inactive, the folds are circular; when the walls contract, the folds change in direction, to become longitudinal. This phenomenon is confirmed by in vivo baboon studies and elucidated by wire spirals. It is seen to be an inherent characteristic of 'peristaltic' and 'segmental' contractions. In this manner longitudinal mucosal furrows are formed simultaneously with the contraction wave of the walls, thus facilitating transit. Were this not so, peristalsis would be an ineffective mechanism, with contraction waves acting against the resistance of circular folds.