Transverse folds of rectum

Transverse folds of rectum

Coronal section of rectum and anal canal.

Anatomy of the anus and rectum
Details
Identifiers
Latin Plicae transversae recti
Dorlands
/Elsevier
p_24/12649311
TA A05.7.04.007
FMA 75657

Anatomical terminology

The transverse folds of rectum (or Houston's valves) are semi-lunar transverse folds of the rectal wall that protrude into the rectum, not the anal canal as that lies below the rectum. Their use seems to be to support the weight of fecal matter, and prevent its urging toward the anus, which would produce a strong urge to defecate. Although the term rectum means straight, these transverse folds overlap each other during the empty state of the intestine to such an extent that, as Houston remarked, they require considerable maneuvering to conduct an instrument along the canal, as often occurs in sigmoidoscopy and colonoscopy.

These folds are about 12 mm. in width and are composed of the circular muscle coat of the rectum. They are usually three in number; sometimes a fourth is found, and occasionally only two are present.

Transverse folds were first described by a British anatomist John Houston, a curator of Dublin College of Surgeon's Museum, in 1830. They appear to be peculiar to human physiology: Baur (1863) looked for Houston's valves in a number of mammals, including wolf, bear, rhinoceros, and several Old World primates, but didn't find any. They are formed very early during human development, and may be visible in embryos of as little as 55 mm in length (10 weeks of gestational age.)[1]

External links

References

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)

  1. P.H.S.Silver (1955). "Observation on the Valves of Houston in the human embryo and foetus" (PDF). Journal of Anatomy 89 (2): 217–24. PMC 1244784. PMID 14367217.


This article is issued from Wikipedia - version of the Saturday, April 18, 2015. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.