Houston valve

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Houston valve
Coronal section of rectum and anal canal.
Anatomy of the anus and rectum
Latin	plicae transversae recti
Gray's	subject #249 1183
Dorlands/Elsevier	p_24/12649311

Houston's valves (or transverse folds of rectum) are semi-lunar transverse folds of the rectal wall that protrude into the anal canal. 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.

• One is situated near the commencement of the rectum, on the right side.
• A second extends inward from the left side of the tube, opposite the middle of the sacrum.
• A third, the largest and most constant, projects backward from the forepart of the rectum, opposite the fundus of the urinary bladder.
• When a fourth is present, it is situated nearly 2.5 cm above the anus on the left and posterior wall of the tube.

[edit] External links

• Shafik A, Doss S, Ali Y, Shafik A (2001). "Transverse folds of rectum: anatomic study and clinical implications.". Clin Anat 14 (3): 196–203. doi:10.1002/ca.1033. PMID 11301467. 
• Norman/Georgetown pelvis (rectum)

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

v • d • e Anatomy of torso, digestive system: Gastrointestinal tract Upper GI: to stomach Mouth • Pharynx (nasopharynx, oropharynx, hypopharynx) • Esophagus • Crop Upper GI: stomach rugae – gastric pits – cardia/gland – fundus/gland – pylorus/gland – pyloric antrum – pyloric canal – greater curvature – lesser curvature – angular incisure Lower GI: intestines Small intestine: Duodenum (Suspensory muscle, Major duodenal papilla, Minor duodenal papilla) • Duodenojejunal flexure • Jejunum • Ileum • continuous (intestinal villus, crypts of Lieberkühn, circular folds) Junction: Vermiform appendix • Ileocecal valve Large intestine: Cecum • Colon (ascending colon, hepatic flexure, transverse colon, splenic flexure, descending colon, sigmoid colon) • continuous (taenia coli, haustra, epiploic appendix) Lower GI: termination Rectum: Houston valve • rectal ampulla • pectinate line Anal canal: anal valves • anal sinuses • anal columns • Hilton's white line Anus: Sphincter ani internus muscle • Sphincter ani externus muscle Lower GI: lymph GALT: Peyer's patches (M cells)