Mucosa, Submucosa, Muscularis and Adventitia are the four layers of the _______ wall.

Mucosa, Submucosa, Muscularis and Adventitia are the four layers of the gastrointestinal wall.The mucosa is the innermost layer of the gastrointestinal tract. It SURROUNDS the lumen of the tract, and comes into direct contact with digested food.The submucosa is a thin layer of tissue in the gastrointestinal tract. It is the layer of dense irregular connective tissue that supports the mucosa and joins it to the muscular layer, the bulk of OVERLYING smooth muscle.The adventitia is the OUTER layer of fibrous connective tissue surrounding the tract.In the gastrointestinal tract, the muscular layer is bounded in most cases by SEROSA. However, at the ORAL cavity, thoracic esophagus, ascending colon, descending colon and the rectum, the muscular layer is instead bounded by adventitia.