| anal valves | Delicate crescent-shaped mucosal folds that pass between the lower ends of neighboring anal columns; the small pocket thus formed is an anal sinus. Synonym: valvulae anales, Morgagni's valves. (05 Mar 2000) |
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| anal verge | The transitional zone between the moist, hairless, modified skin of the anal canal and the perianal skin. (05 Mar 2000) |
| white line of anal canal | A bluish pink, narrow, wavy zone in the mucosa of the anal canal below the pectinate line at the level of the interval between the subcutaneous part of the external sphincter and the lower border of the internal sphincter, said to be palpable. Synonym: Hilton's white line. (05 Mar 2000) |
| subcutaneous part of external anal sphincter | pars subcutanea musculi sphincteri ani externi, subcutaneous portion of external anal sphincter |
| subcutaneous portion of external anal sphincter | pars subcutanea musculi sphincteri ani externi, subcutaneous portion of external anal sphincter |
| superficial part of external anal sphincter | superficial part of external anal sphincter |
| supra-anal | Above the anus. Synonym: superanal. (05 Mar 2000) |
| deep part of external anal sphincter | deep part of external anal sphincter |
| internal anal sphincter | <anatomy> A smooth muscle ring, formed by an increase of the circular fibres of the rectum, situated at the upper end of the anal canal, internal to the outer voluntary external anal sphincter. This sphincter is maximally-contracted when the rectal ampulla is at rest -empty or relaxed to accommodate a distending faecal mass. It is inhibited with filling of the ampulla, increased distension and peristalsis. Synonym: musculus sphincter ani internus, internal sphincter muscle of anus. (05 Mar 2000) |
| external anal sphincter | A fusiform ring of striated muscular fibres surrounding the anus, attached posteriorly to the coccyx and anteriorly to the central tendon of the perineum; it is subdivided, often indistinctly, into a subcutaneous part, a superficial part and a deep part for descriptive purposes. Synonym: musculus sphincter ani externus, external sphincter muscle of anus. (05 Mar 2000) |