Rectum

Rectum is a short tube located at the end of the large intestine, which connects the intestine to the anus.

Stomach colon rectum diagram

Digital rectal exam

Rectum and anus

Rectum (definition)

The rectum is the final section of the large intestine, terminating in the anus. It functions as a temporary storage site for feces before they are expelled from the body.

Anatomy and Function

The rectum is approximately 12-15 cm in length and extends from the end of the sigmoid colon to the anal canal. Unlike other sections of the large intestine, the rectum lacks the distinct pouches or haustra. It is lined with layers of muscle and mucous membranes.

• Function: Its primary role is to store fecal matter until the body is ready for defecation. The walls of the rectum allow for the expansion as feces accumulate. When the rectum is full, the increase in pressure activates stretch receptors, signaling the need to defecate.

Relation to Other Structures

• Anus: The rectum ends at the anus, the opening through which feces pass out of the body. The anus contains internal and external sphincter muscles that help control defecation.
• Large intestine: The rectum is the concluding segment of the large intestine, following the sigmoid colon.

Clinical Importance

Diseases and Disorders

• Rectal cancer: A malignancy that arises from the lining of the rectum. Symptoms may include blood in the stool, pain, and changes in bowel habits.
• Hemorrhoids: Swollen blood vessels in the rectum or anus that can be painful and may bleed.
• Rectal prolapse: A condition where the rectum slips outside the anus.

Diagnostic Procedures

• Rectal examination: A manual inspection by a healthcare provider to check for abnormalities in the rectum called digital rectal examination.
• Colonoscopy: An endoscopic examination of the large intestine and rectum using a camera attached to a flexible tube.

History

Historically, various cultures have had differing views and treatments related to rectal diseases and disorders. Ancient civilizations, such as the Egyptians and Greeks, documented early treatments for hemorrhoids and other rectal conditions.

See Also

• Digestive System
• Colon
• Anus
• Hemorrhoids
• Colonoscopy

References

• Smith, J.A. (2002). Anatomy and Physiology of the Rectum. Medical Press.
• Harrison, P.L. (1998). Digestive System: An Overview. University Press.