Rectum

(redirected from Anal cavity)
Also found in: Dictionary, Thesaurus, Encyclopedia.

rectum

 [rek´tum]
the distal portion of the large intestine, beginning anterior to the third sacral vertebra as a continuation of the sigmoid and ending at the anal canal. The feces, the solid waste products of digestion, are formed in the large intestine and are gradually pushed down into the rectum by the muscular action of the intestine. Distention of the rectum by the accumulating feces sets up nerve impulses that indicate to the brain the need to empty the bowels. The rectum is 15 to 20 cm (6 to 8 inches) long, with the anal canal making up the last segment. The anus is kept closed (except during the evacuation process) by muscular rings called the anal sphincters.



In a rectal examination, the examiner palpates the rectum by inserting a gloved and lubricated finger into the rectum. The examination helps in determining whether there are masses in the rectum or pelvic region, and in determining the size and texture of the prostate in men. More extensive examination of the interior surface of the rectum may be done by proctoscopy.

rec·tum

, pl.

rec·tums

,

rec·ta

(rek'tŭm; -tŭmz, rek'tă), [TA] Avoid the colloquial and jargonistic use of this word as a synonym of anus.
The terminal portion of the digestive tube, extending from the rectosigmoid junction to the anal canal (perineal flexure).
[L. rectus, straight, pp. of rego, to make straight]

rectum

/rec·tum/ (rek´tum) the distal portion of the large intestine.

rectum

(rĕk′təm)
n. pl. rec·tums or rec·ta (-tə)
The terminal portion of the large intestine, extending from the sigmoid colon to the anal canal.

rectum

[rek′təm] pl. rectums, recta
Etymology: L, rectus
the lower part of the large intestine, about 12 cm long, continuous with the descending sigmoid colon, proximal to the anal canal. It follows the sacrococcygeal curve, ends in the anal canal, and usually contains three transverse semilunar folds: one situated proximally on the right side, a second one extending inward from the left side, and the third and largest fold projecting caudally. Each fold is about 12 mm wide. The folds overlap when the intestine is empty or defecation occurs. rectal, adj.
enlarge picture
Rectum

rec·tum

, pl. rectums, recta (rek'tŭm, -tŭmz, -tă) [TA]
The terminal portion of the digestive tube, extending from the rectosigmoid junction to the anal canal.
[L. rectus, straight, pp. of rego, to make straight]

rectum

(rĕk′tŭm) [L., straight]
Enlarge picture
RECTUM: Rectum seen during colonoscopy
The lower part of the large intestine, about 5 in (12.7 cm) long, between the sigmoid colon and the anal canal. Its smooth muscle layer is the effector for the defecation reflex, the reflex centers for which are in the second, third, and fourth sacral segments of the spinal cord. See: illustration;

rectum

The 12.5 cm long, very distensible terminal segment of the large intestine, situated immediately above the anal canal. In spite of its name (rectus is Latin for straight), the rectum is curved and follows the hollow of the SACRUM. Its lining is smooth and the whole of the inside is accessible to the examining finger (see RECTAL EXAMINATION). Movement of bowel contents into the rectum causes the desire to defaecate.

rectum

the terminal part of the intestine of an animal which opens into the ANUS or CLOACA.

Rectum

The lower section of the large intestine, a digestive system organ. After food has passed through the stomach and intestines and been digested, the leftover material, in the form of feces, enters the rectum, where it stays until defecation.

rectum

the distal portion of the large intestine, beginning at the pelvic inlet and ending at the anal canal. The feces, the solid waste products of digestion, are formed in the large intestine and are gradually pushed into the rectum by the muscular action of the intestine. Distention of the rectum by the accumulating feces sets up nerve impulses that indicate to the brain the need to empty the bowels; defecation follows. See also rectal.