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the sphincter muscle of the anus

the sphincter muscle of the anus

Ring-like muscle of anus, controlling passage of feces.

Many anatomists have described two sphincter muscles of the anus :-1. The S. exter’nus seu cuta’neus, Aspidiscos, Coccygio-cutane-sphincter, Orbicula'ris Recti, Constric'tor Ani, Coccygio-anal, (Ch.) It is situate around the anus; is elliptical from before to behind; flattened, and pierced at its middle. Its fibres describe concentric arcs, which are attached, behind, to the extremity of the coccyx, by a dense, areolar substance; and are confounded, anteriorly, with the bulbo-cavernosi and transversi perinasi muscles. This muscle contracts and closes the anus. 2. The inner or internal Sphincter Ani, Sphincter intestina'lis of Winslow, is by many anatomists considered as the termination of the circular fibres of the rectum. It is annular, and situate around the inferior extremity of the rectum, to the extent of about a finger’s breadth. It has the same uses as the other.