Motricité du côlon et du rectum

The large bowel has two main functions: the absorption of water and electrolytes unabsorbed in the small bowel and the storage of stools between bowel movements. Colonic motor patterns are both tonic and phasic contractions. Phasic contractions are, in most of the cases, short clustered and non propagated contractions, separated by long periods of motor rest, especially at night. However, the most characterized colonic motor patterns are high-amplitude propagated contractions, occurring mainly at awakening and after meals and promoting aboral movements of the colonic content. Colonic nervous structures are both intrinsic and extrinsic. Intrinsic structures are the two plexuses of the enteric nervous system but also intestitial cells of Cajal. Extrinsic innervation plays a major role in modulating intrinsic nervous control, mainly after the meals that remain the major stimulant of colonic motility. Rectum and anal sphincters are essential for both defecation and continence. Their physiology involves smooth and striated muscles. The nervous control of recto-anal motility depends again from both intrinsic et extrinsic structures. Sensory nerves are key factor for continence.