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The internal anal sphincter can not close the anal canal completely
B Lestar1, F Penninckx, H Rigauts
1Department of Abdominal Surgery, University Clinics Gasthuisberg, Catholic University of Leuven, Belgium.
International Journal of Colorectal Disease
|September 1, 1992
Abstract:
We determined the maximum closing capability of the internal anal sphincter muscle ring in vitro and in vivo. The internal sphincter, 4 to 6 mm thick, cannot close the anal canal hermetically, not even during maximal contraction. The blood-filled anal cushions have to fill up an intrasphincteric gap of at least 7 to 8 mm in diameter.