a. Mucosal layer made up of villi projections. | b. Submucosa containing connective tissue, glands and blood vessels folds under the mucosal layer. |
c. Muscularis with circular and longitudinal muscle layers. | d. Serosa made up of viseral peritoneum and mesentery. |
Note the folding of the intestinal muscoa into structures called plicae circulares which increase absorptive surface area. | |
Click on the green squares to see details of each layer of the duodenum wall. |