Houston valve

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

Although the term rectum means straight, the human rectum is not. There are certain permanent transverse folds, of a semilunar shape, known as Houston’s valves (or transverse folds of rectum). They project into the lumen of the rectum.

These folds are about 12 mm. in width, and contain some of the circular fibers of the gut.

In the empty state of the intestine they overlap each other, as Houston remarks, so effectually as to require considerable maneuvering to conduct a bougie or the finger along the canal.

Their use seems to be, to support the weight of fecal matter, and prevent its urging toward the anus, where its presence always excites a sensation demanding its discharge.

They are formed from circular muscle coat of the rectal wall.

Details on each fold

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.

Clinical significance

During sigmoidoscopy and colonoscopy the scope is moved around to negotiate these folds.

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. 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 As such, some of the information contained herein may be outdated.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.

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)