| rectosigmoid | <anatomy> The rectum and sigmoid colon considered as a unit; the term is also applied to the junction of the sigmoid colon and rectum. (05 Mar 2000) |
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| rectosigmoid junction | <anatomy> The site where the sigmoid colon becomes the rectum; usually takes the form of an acute angle, demarcated externally by a discontinuation of appendices epiploicae, a spreading out of the teniae coli to completely encircle the rectum, and consequently, termination of the sacculations (haustrae) between the teniae. (05 Mar 2000) |
| rectosigmoid sphincter | <anatomy> A circular band of muscular fibres at the recto sigmoid junction. Synonym: O'Beirne's sphincter, O'Beirne's valve, pelvirectal sphincter. (05 Mar 2000) |