External anal sphincter - Wikipedia
Dr Aaron Wong. Hereditary internal anal sphincter myopathy: the first Caribbean family.
It can be felt on rectal examination. (2) It can be put into a condition of greater contraction under the influence of the will, so as more firmly to occlude the anal aperture, in expiratory efforts unconnected with defecation.
The external anal sphincter (or sphincter ani externus ) is a flat plane of muscular fibers, elliptical in shape and intimately adherent to the skin surrounding the margin of the anus. Contents, anatomy edit, the external anal sphincter measures about 8 to 10 cm in length, from its anterior to its posterior extremity, and is about.5 cm opposite the anus, when defecation occurs the sphincter muscle retracts.