ABDICATION ABDOMEN 15 and St. Jude into Persia, by whom he was made the first bishop of Babylon. ABDICATION, the abandonment of a throne by a crowned head, was rare and generally compulsory in ancient times. The abdication of Diocletian and Maximian is the best known case in antiquity. Among modern princes who have more or less voluntarily laid down their crowns, we find Charles V. of Spain and Ger- many (1556); Christina of Sweden (1654); in Poland, John Casimir (1669); in Spain, Philip V. (1724) and Charles IV. (1808); in Savoy and Sardinia, Amadeus VIII. (1434), Victor Amadeus II. (1730), Victor Emanuel I. (1821), and Charles Albert (1849); in France, Napoleon I. (1814 and 1815), Charles X. (1830), and Louis Philippe (1848) ; in Hol- land, Louis Bonaparte (1810) and William I. (1840); in Bavaria, Louis I. (1848); in Aus- tria, Ferdinand (1848). The most recent and one of the most remarkable of royal abdications is that of King Amadeus of Spain, who after a reign of two years became disgusted with the difficulties of his position, and on Feb. 11, 1873, resigned the crown for himself and heirs, and returned to his native Italy. Abdication, vol- untary or compulsory, is considered by jurists as a personal act, which in no wise affects the right of succession. " ABDOMEN (Lat., of undetermined etymology), the lower part of the body, included between the level of the diaphragm and that of the pelvis. The abdomen consists of its walls or boundaries, the cavity embraced by them, and the organs or viscera included therein. The walls are con- stituted below by the pelvis, a strong basin- shaped bone with wide flaring edges, upon the upper surface of which the weight of the ab- dominal organs is sustained ; behind by a part of the spinal column and the strong muscles attached to its sides ; above by the diaphragm, a vaulted muscular sheet, which forms the par- tition between the cavity of the abdomen and that of the chest ; and in front by the abdomi- nal muscles and their integuments, extending from the lower part of the chest to the pelvis. In front and laterally, the abdominal walls are soft and flexible, being composed only of the skin, fatty tissue, fibrous membranes, and mus- cles ; behind they are more solid and unyield- ing, owing to the bony framework of the spinal column, which here forms so large a part of their substance. For convenience of anatomi- cal examination and reference, the abdomen is divided externally into three nearly equal transverse bands or zones, an upper, middle, and lower; these zones being again divided into three nearly equal parts or "regions," namely, one middle and two lateral regions in each zone. In the upper zone the middle re- gion is the epigastrium (Gr. em, over, and yaarqp, the stomach), because a portion of the stomach is situated immediately beneath it; the two lateral regions of the same zone being the right and left hypochondria (VTTO, under, and ov<?pof, a cartilage), because these two re- gions are beneath the cartilages of the lower ribs. In the middle zone, the median portion is the umbilical region, so called because it contains the umbilicus or navel ; the two lat- eral portions are the right and left lumbar re- gions, or the loins. In the lowermost zone, the middle region forms the hypogastrium (I>TTO and yaarrip), and the two lateral portions the right and left iliac regions, which are oc- cupied on each side by the ilium, or flaring portion of the pelvis. The cavity of the abdo- men is lined by a very extensive and delicate membrane, the peritoneum (Gr. KEPITEIVEIV, to extend around), which is also reflected over the surfaces of the abdominal organs, as the covering of a chair or sofa may be reflected or extended over its cushion. In the case of those abdominal organs which remain fixed in their places, like the pancreas and the kidneys, the peritoneum simply passes over their ante- rior surfaces; but those which are movable, like the liver, stomach, and intestines, are more or less completely invested by it, some of them being attached to the posterior abdomi- nal walls only by the double layer of perito- neum, returning upon itself after having cov- ered their exterior. Thus, these organs are covered, and the abdominal walls are lined, by opposite surfaces of the same continuous peri- toneal membrane; and these surfaces are moistened by a minute quantity of serous fluid, which enables them to move gently to and fro upon each other, without causing friction or irritation of the parts. The organs con- tained in the abdomen are as follows : In the upper zone, the liver, stomach, spleen, pancreas, and the commencement of the small intestine ; in the middle zone, the mass of the small intestine, with portions of the large intestine, the kidneys, and the supra- renal capsules ; and in the lowermost zone, the remainder of the small and largo intestines. The very last portion of the large intestine oc- cupies the deeper parts of the cavity of the pelvis, together with the urinary bladder and the uterine organs. Owing to the flexible character of the abdominal walls, much infor- mation may be obtained regarding the condi- tion of the internal organs by external manual examination. If an organ be enlarged, indu- rated, or displaced, these changes may be de- tected by careful manipulation, and their in- crease or diminution may be determined from day to day. If one or more of them be in- flamed, this condition is indicated by an un- natural tenderness on pressure ; and the exact situation and character of the inflammation may often be fixed by observing whether the tenderness be superficial or deep-seated. Un- natural growths and tumors may be detected in the same way, and their origin ascertained in many cases with considerable approach to certainty. Penetrating wounds of the abdo- men are very dangerous, because the contents of the stomach and intestines, if allowed to es- cape into the cavity of the peritoneum, pro-
