Abstract Colonic functions include the absorption of water and electrolytes, storage of intraluminal contents until elimination is socially convenient, and nutrient salvage from bacterial metabolism of carbohydrates that are not absorbed in the small intestine. Colonic motor activity is extremely irregular, ranging from quiescence to isolated contractions, bursts of contractions, or propagated contractions. Functional constipation is defined by two or more of the following symptoms: 1) fewer than three defecations per week, 2) straining, 3) lumpy or hard stools, 4) sensation of incomplete evacuations, 5) sensation of anorectal obstruction or blockage, and 6) manual maneuvers to facilitate defecation. Functional defecatory disorders are characterized by disordered defecation caused by functional obstruction that results from impaired relaxation of the external anal sphincter, impaired relaxation of the puborectalis muscle, or inadequate propulsive forces, or some combination of these.