ABDOMEN

the part of the trunk of the human body below the diaphragm which divides the cavity of the trunk (into the abdominal cavity and the thoracic cavity); further divided into the a. proper above and the pelvis below, the former containing the stomach, small and large intestine, liver, pancreas, spleen, and kidneys, and the latter the lower part of the large intestine the urinary bladder, and the internal genital organs. Internally the a. is lined with a serous membrane called the peritoneum, which covers the free surfaces of the abdominal organs and holds the intestine in place by means of a fold called the mesentery, while another fold, the great omentum, covers like an apron the front of the greater part of the abdominal contents. Owing to the modern dvances of medicine, and chiefly to the introduction of ans the tics and antiseptic and aseptic surgery, opening the a. for the relief of disease is an everyday procedure, and one which, with due care, involves very little risk; and, as an aid to diagnosis in obscure cases, opening the a. by incision for the purpose of examining its contents is by no means unusual.