| musculus levator ani | <anatomy> Formed by pubococcygeus and iliococcygeus muscles; origin, posterior body of pubis, tendinous arch of the levator ani, and spine of ischium; insertion, anococcygeal ligament, sides of the lower part of the sacrum and of coccyx; action, resists prolapsing forces and draws the anus upward following defecation; supports the pelvic viscera; nerve supply, nerve to levator ani (fourth sacral spinal nerve). Synonym: musculus levator ani, elevator muscle of anus. (05 Mar 2000) |
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| musculus sphincter ani externus | 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) |
| musculus sphincter ani internus | <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) |
| crena ani | The sulcus between the buttocks (nates). Synonym: crena ani, anal cleft, crena clunium, gluteal cleft. (05 Mar 2000) |
| sphincter ani tertius | The third sphincter of the anorectum, a physiological sphincter at the sigmoidorectal junction. (05 Mar 2000) |
| tendinous arch of levator ani muscle | <anatomy> A thickened portion of the obturator fascia that extends in an arching line from the pubis posteriorly to the ischial spine and gives origin to part of the levator ani muscle. Synonym: arcus tendineus musculi levatoris ani, arcus tendineus of obturator fascia. (05 Mar 2000) |
| levator ani muscle | <anatomy> Formed by pubococcygeus and iliococcygeus muscles; origin, posterior body of pubis, tendinous arch of the levator ani, and spine of ischium; insertion, anococcygeal ligament, sides of the lower part of the sacrum and of coccyx; action, resists prolapsing forces and draws the anus upward following defecation; supports the pelvic viscera; nerve supply, nerve to levator ani (fourth sacral spinal nerve). Synonym: musculus levator ani, elevator muscle of anus. (05 Mar 2000) |