The final straight section of the large intestine that stores fecal material before elimination.
Structure
The rectum is roughly 12 to 15 centimeters long. Its inner surface has three transverse folds called the valves of Houston that help support waste. Its walls contain the same muscle layers as the rest of the colon.
Function
Mass movements in the colon push feces into the rectum a few times each day. Stretch receptors in the rectal wall trigger the urge to defecate when its volume increases.
Continence
Two sphincters guard the anal canal: an internal sphincter of smooth muscle under autonomic control, and an external sphincter of skeletal muscle under voluntary control.
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Rectum starts with R and ends with M. Browse other body parts along the same letter.
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