MICROANATOMY

Detailed explanation-1: -The muscularis externa is responsible for segmental contractions and peristaltic movement in the GI tract. These muscles cause food to move and churn together with digestive enzymes down the GI tract. The muscularis externa consists of an inner circular layer and a longitudinal outer muscular layer.

Detailed explanation-2: -Primary peristalsis is initiated by a swallow and is the main source of esophageal transit whereas distension-induced or secondary peristalsis functions to maintain an empty esophagus by clearing refluxate from the stomach [1] in the absence of swallowing.