Main Model
13 Anococcygeal ligament
The anal canal, surrounded by internal and external anal sphincters, descends postero-inferiorly between the anococcygeal ligament and the perineal body. The canal is collapsed, except during passage of feces. Both sphincters must relax before defecation can occur.
The external anal sphincter is a large voluntary sphincter that forms a broad band on each side of the inferior two thirds of the anal canal. This sphincter is attached anteriorly to the perineal body and posteriorly to the coccyx via the anococcygeal ligament.