Which layer of the alimentary canal is responsible for segmentation and peristalsis?

A) Serosa

B) muscularis externa

C) mucosa

D) submucosa

B) muscularis externa

Explanation:

Muscularis externa is a muscle layer of gastrointestinal tract (GI) that consists of an inner circular muscular layer and a longitudinal outer muscular layer.

Peristalsis is one-way contraction (followed by relaxation) of muscles found in GI which moves the caudal direction. Peristalsis involves rhythmic contractions of the longitudinal muscles in the gastrointestinal tract, most commonly in the eosophagus.

Segmentation is also process of muscular contractions in the GI. Segmentation involves contractions of the circular muscles in the digestive tract and its function is to move chyme in both directions.