mechanisms of continence

Last reviewed 01/2018

There are number of mechanisms which maintain continence:

  • sigmo-rectal 'sphincter':
    • rectal contraction is a reflex response to filling
    • contraction is inhibited cortically
    • a temporary holdup of faeces at the acute angle of the pelvic loop of the sigmoid colon may aid continence

  • ano-rectal angle:
    • the pubo-rectalis sling maintains the acute angle between the rectum and the anus, preventing passage of the stool into the anal canal

  • anal sphincters:
    • external sphincter - striated muscle, voluntary
    • internal sphincter - smooth muscle
    • vascular cushions complete the seal

  • ano-rectal sensation:
    • the ability to distinguish flatus and stool is especially important in the presence of diarrhoea