The physiology of human defecation

Dig Dis Sci. 2012 Jun;57(6):1445-64. doi: 10.1007/s10620-012-2071-1. Epub 2012 Feb 26.


Human defecation involves integrated and coordinated sensorimotor functions, orchestrated by central, spinal, peripheral (somatic and visceral), and enteric neural activities, acting on a morphologically intact gastrointestinal tract (including the final common path, the pelvic floor, and anal sphincters). The multiple factors that ultimately result in defecation are best appreciated by describing four temporally and physiologically fairly distinct phases. This article details our current understanding of normal defecation, including recent advances, but importantly identifies those areas where knowledge or consensus is still lacking. Appreciation of normal physiology is central to directed treatment of constipation and also of fecal incontinence, which are prevalent in the general population and cause significant morbidity.

Publication types

  • Review

MeSH terms

  • Anal Canal / innervation
  • Anal Canal / physiology*
  • Constipation / etiology
  • Constipation / physiopathology
  • Defecation / physiology*
  • Fecal Incontinence / etiology
  • Fecal Incontinence / physiopathology
  • Female
  • Gastrointestinal Tract / innervation
  • Gastrointestinal Tract / physiology
  • Humans
  • Male
  • Manometry / methods
  • Motor Activity / physiology*
  • Pelvic Floor / physiology
  • Peristalsis / physiology*
  • Rectum / innervation
  • Rectum / physiology
  • Reference Values