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Figures in Case Report by Peter Petros(*) - Michael Swash(**)

(*) Royal Perth Hospital, University of Western Australia
(**) Dept of Neurology, The Royal London Hospital, London, UK

Study No. 7: Role of puborectalis muscle in anal continence. Comments on original 4D pelvic ultrasound data from Chantarasorn & Dietz

 

(Fig. 1)

 

The principal closure

Figure 1. –The principal closure mechanism for the anorectum is stretching and narrowing of the rectal tube by posterior muscle forces (arrows) acting against an anus immobilized by puborectalis (PRM) contraction. This action increases the resistance to leakage exponentially inversely with the 4th power of the diameter. LP = levator plate; LMA = longitudinal muscle of the anus.

 

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