Stomach has an extra muscle in its muscular layer known as the oblique muscle which aids mechanical digestion in the stomach. Folds known as rugae are present in the mucosa layer of the stomach which increases the surface area for the absorption of nutrients and also provide greater volume capacity.
Mucosa layer of the stomach have gastric glands buried in it. It has two layers known as superficial foveolar layer and glandular layer. Superficial layer has surface mucous cells that produce specially formulated mucus to protect the walls of the stomach from the action of HCl.