Overview Large intestinal motility functions fecal material moves from cecum through colon, to rectum, and to anal canal colon includes ascending, transverse, descending, and sigmoid colons fecal material is destined for excretion segmentation contractions mix intestinal contents of large intestine occur in cecum and proximal colon contractions are associated with characteristic sac-like segments called haustra in large intestine mass movements move intestinal contents of large intestine over long distances 1-3 times per day propel fecal material into rectum fecal material in distal colon is semi-solid and moves slowly a consequence of colonic water absorption occurring in distal colon defecation rectosphincteric reflex as rectum fills with fecal material, smooth muscle wall of rectum contracts and internal anal sphincter relaxes defecation does not occur external anal sphincter, composed of striated muscle, is under voluntary control external anal sphincter is tonically contracted once rectum fills to 25% capacity, there is an urge to defecate when convenient to defecate, external anal sphincter is relaxed voluntarily smooth muscle wall of rectum contracts and generates sufficient pressure fecal material is forced out through anal canal gastrocolic reflex distension of stomach by food → ↑ motility of colon → ↑ frequency of mass movements in large intestine