_Abdominal Region._—The abdomen is the inferior cavity of the trunk of the body; it is bounded in front and at the sides by the lower ribs and abdominal muscles, above by the diaphragm, and below by the pelvis, and contains the alimentary canal, the organs subservient to digestion, viz.: the liver, pancreas and spleen, and the organs of excretion, the kidneys and the supra-renal capsules. The abdomen may be divided into three regions; in the upper region will be seen the liver, extending across from the right to the left side, the stomach and spleen on the left, and the pancreas and duodenum behind; in the middle region is the transverse part of the colon, with the upper part of the ascending and descending colon, omentum, small intestines, mesentery, and behind, the kidneys and supra-renal capsules; in the inferior region is the lower part of the omentum and small intestines, ascending and descending colon, and ureters. _Fascia_ (from fascia, a bandage) is the name assigned to laminæ of various extent and thickness, which are distributed through different regions of the body for the purpose of investing or protecting the softer or more delicate organs. From a consideration of their structure, these fasciæ may be arranged into two groups: areolo-fibrous fascia, and aponeurotic fascia. The areolo-fibrous fascia is best illustrated by the common subcutaneous investment of the entire body, the superficial fascia. This structure is situated immediately beneath the integument over every part of the frame, and is the medium of connexion between that layer and the deeper parts; it is composed of areolar and elastic tissues, and contains an abundance of adipose cells. The fat, being a bad conductor of caloric, serves to retain the warmth of the body, while it forms at the same time a yielding tissue, through which minute vessels and nerves pass to the skin without incurring the risk of obstruction from injury or pressure. The aponeurotic fascia is the strongest kind of investing membrane; it is composed of tendinous fibres running parallel with each other and connected by other fibres of the same kind passing in different directions, together with areolar tissue and fine elastic fibres. In the limbs, it constitutes the deep fascia, inclosing and forming distinct sheaths to all the muscles and tendons. It is thick on the outer and least protected side of the limb, and thinner at its inner side.