Editing Functional constipation (section)

== Causes ==
To be considered functional constipation, symptoms must be present at least a fourth of the time.<ref name="ACG" /> Possible causes are:
* [[Anismus]]
* [[Descending perineum syndrome]]
* Other inability or unwillingness to control the [[external anal sphincter]], which normally is under [[volition (psychology)|voluntary]] control
* A poor [[diet (nutrition)|diet]]
* An unwillingness to defecate
* Nervous reactions, including prolonged and/or chronic stress and anxiety, that close the [[Sphincter ani internus muscle|internal anal sphincter]], a [[muscle]] that is not under voluntary control
* Deeper [[psychosomatic]] disorders which sometimes affect [[digestion]] and the [[absorption (small intestine)|absorption]] of [[water]] in the [[Colon (anatomy)|colon]]
There is also possibility of presentation with other comorbid symptoms such as headache, especially in children.<ref>{{cite journal|title=Comorbidity of headache and functional constipation in children: a cross-sectional survey.|journal=Turk J Gastroenterol|pmid=25417610|doi=10.5152/tjg.2014.6183|volume=25|issue=5|year=2014|vauthors=Inaloo S, Dehghani SM, Hashemi SM, Heydari M, Heydari ST|pages=508–11}}</ref>