[L. abdomen.] In the human body the trunk is divided by the diaphragm into two cavities - the upper being the thorax or chest, and the lower the abdomen or belly. The abdomen contains the stomach, liver, intestines, spleen, pancreas, kidneys, etc. It is lined by a serous membrane, which is folded over the organs, and allows them a certain freedom of movement, but keeps them in their proper relations to each other. (See Bowels.)