Rectosigmoid junction

The rectosigmoid junction, formerly the rectosigmoid sphincter or sphincter of O'Beirne, is the junction of the sigmoid colon and the rectum. ^[1]

Hypothesized sphincter

The rectosigmoid sphincter, also known as the sphincter of O'Beirne, was hypothesized as an anatomical structure located between the sigmoid colon and rectum. ^[1] The structure was first proposed by the 19th-century Irish surgeon James O'Beirne. Its existence, structure and function has been a matter of long-standing medical controversy. ^{[1] [2]} The Latin names sphincter ani tertius and pylorus sigmoidrectalis also been used. ^{[3] [4]}

As of 2025 ^[update] , the existence of some form of distinct contractile anatomical structure at the rectosigmoid junction, if not an actual sphincter, in many people is acknowledged in numerous articles in the medical literature. ^{[3] [1] [5] [6] [7] [8] [9] [10]}

Molecular signature of rectosigmoid junction cancer

A 2023 study suggested that cancers of the rectosigmoid junction exhibit different chemical signatures from either cancers of the colon or cancers of the rectum. ^[11]

References

1. Ballantyne, G. H. (August 1986). "Rectosigmoid sphincter of O'Beirne". Diseases of the Colon and Rectum. 29 (8): 525–531. doi:10.1007/BF02562612. ISSN   0012-3706. PMID   3525042.
2. Chen, Ji-Hong; Nirmalathasan, Sharjana; Pervez, Maham; Milkova, Natalija; Huizinga, Jan D. (October 2021). "The Sphincter of O'Beirne - Part 1: Study of 18 Normal Subjects". Digestive Diseases and Sciences. 66 (10): 3516–3528. doi:10.1007/s10620-020-06657-w. ISSN   1573-2568. PMID   33462748.
3. Steele, Scott R.; Hull, Tracy L.; Hyman, Neil; Maykel, Justin A.; Read, Thomas E.; Whitlow, Charles B. (2021-11-20). The ASCRS Textbook of Colon and Rectal Surgery. Springer Nature. p. 18. ISBN   978-3-030-66049-9.
4. "sphincter ani tertius". Farlex Partner Medical Dictionary. Retrieved 2025-10-30.
5. Trzpis, Monika; Sun, Ge; Chen, Ji-Hong; Huizinga, Jan D.; Broens, Paul (January 2023). "Novel insights into physiological mechanisms underlying fecal continence". American Journal of Physiology-Gastrointestinal and Liver Physiology. 324 (1): G1 –G9. doi:10.1152/ajpgi.00313.2021. ISSN   0193-1857. PMID   36283962.
6. Shafik, Ahmed; Mostafa, Randa M.; Shafik, Ali A. (2002). "Electrophysiological study of the rectosigmoid canal: evidence of a rectosigmoid sphincter". Journal of Anatomy. 200 (5): 517–521. doi:10.1046/j.1469-7580.2002.00049.x. ISSN   1469-7580. PMC   1570712 . PMID   12090397.
7. Shafik, A.; Doss, S.; Asaad, S.; Ali, Y. A. (November 1999). "Rectosigmoid junction: anatomical, histological, and radiological studies with special reference to a sphincteric function". International Journal of Colorectal Disease. 14 (4–5): 237–244. doi:10.1007/s003840050217. ISSN   0179-1958. PMID   10647633.
8. Shafik, Ahmed; Asaad, Soheir; Doss, Sameh (March 2003). "Identification of a sphincter at the sigmoidorectal canal in humans: histomorphologic and morphometric studies". Clinical Anatomy (New York, N.Y.). 16 (2): 138–143. doi:10.1002/ca.10054. ISSN   0897-3806. PMID   12589668.
9. Shafik, Ahmed; Shafik, Ali A.; Sibai, Olfat El; Ahmed, Ismail; Mostafa, Randa M. (2006-01-01). "Role of the Rectosigmoidal Junction in Fecal Continence: Concept of the Primary Continent Mechanism". Archives of Surgery. 141 (1). doi:10.1001/archsurg.141.1.23. ISSN   0004-0010. PMID   16415407. Archived from the original on 2023-06-10.
10. Shafik, A. (April 1997). "The hypertonic rectosigmoid junction: description of a new clinicopathologic entity causing constipation". Surgical Laparoscopy & Endoscopy. 7 (2): 116–120. doi:10.1097/00019509-199704000-00009. ISSN   1051-7200. PMID   9109239.
11. Zhu, Qiuwei; Zhu, Chenyang; Zhang, Xiaotao; Zhu, Xiaodan; Chen, Zhe; Gu, Dejian; He, Yuange; Jin, Chunhui (2023-06-30). "Comprehension of rectosigmoid junction cancer molecular features by comparison to the rectum or sigmoid colon cancer". Journal of Gastrointestinal Oncology. 14 (3): 1307–1319. doi: 10.21037/jgo-23-120 . ISSN   2078-6891. PMC   10331759 . PMID   37435233.

See also

• Taenia coli