Question

Which layer of the wall of the alimentary canal us responsible for motility (peristalsis & segmentation)?

A. submucosa

B. lamina propria

C. muscularis externa

D. serosa

muscularis mucosae

Answer 1

Which layer of the wall of the alimentary canal is responsible for motility (peristalsis and segmentation)?

Answer: C) Muscularis externa.

Explanation:

- The motility (peristalsis and segmentation) of gastrointestinal tract (GIT) occurs due to contraction of smooth muscles in the muscularis externa layer of GIT.
- Peristalsis is mainly caused by the contraction of longitudinal muscle layer of muscularis externa and segmentation is caused by the contraction of circular muscle layer of muscularis externa.
- Peristalsis is a reflex response of gastrointestinal tract (GIT) to stretch which results in organized propulsion of luminal contents of the gut in forward direction.
Segmentation is closely spaced contraction in the small intestine which divides the small intestine into many segments.
- Peristalsis is seen along the entire length of GIT from esophagus to rectum while segmentation is mainly seen in small intestine.