EXPLANATION OF TERMS.
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Sternum.—One of the bones of the thorax; is situated in the middle line in the front of the chest, and is oblique in direction, the superior end lying within a few inches of the vertebral column, the inferior being projected forward so as to be placed at a considerable distance from the spine. The bone is flat or slightly concave in front, and marked by five transverse lines, which indicate its original sub-division into six pieces. It is convex behind, broad and thick above, where it presents a concave border, and narrow at its junction with the middle piece. It is divided into the superior piece or manubrium, the middle piece or body, and the inferior piece, which is the smallest of the three, and varies in appearance, being sometimes pointed, at other times broad and thin, and again, at other times, perforated by a round hole. The seven true ribs are attached at each side of the sternum by means of the costal cartilage.
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 organssubservient 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, whileit 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.
TheSkinis the exterior investment of the body, which it serves to cover and protect. It is continuous at the aperture of the internal cavities with the lining membrane of those cavities, the internal skin or mucous membrane, and is composed essentially of two layers—derma and epidermis. The derma or cutis is chiefly composed of areola-fibrous tissues, besides which it has entering in its structure elastic tissues and smooth muscular fibre, together with blood vessels and nerves. The epidermis or cuticle (scarf-skin) is a product of the derma, which it serves to envelop and defend. That surface of the epidermis which is exposed to the influence of the atmosphere and exterior sources of injury is hard and horny in texture, while that which lies in contact with the under layer is soft and cellular.
Viscera.—The viscera of the human body are situated in the three great cavities—cranio-spinal, thorax and abdomen. The viscera of the cranio-spinal cavity are the brain, with the spinal cord, and the principal organs of sense. The viscera of the chest are, the central organs of circulation, the heart, the organs of respiration, the lungs. The abdominal viscera admit of a sub-division into those which properly belong to that cavity, viz.: the alimentary canal, the liver, pancreas, spleen and kidneys; and those of the pelvis, the bladder and the internal organs of generation.
Cartilage.—In the structure of joints, cartilages serve the double purpose of a connecting and separating medium; in the former capacity possessing great strength; in the latter, smoothness and elasticity. For instance, the costal cartilages unite the ribs with the sternum and form the point of separation by the knife, when it is desired to raise the sternum, as in the preceding process of embalming.
Gall Bladderis the reservoir of the bile; it is a sac situated in a fosse on the under surface of the right lobe of the liver.
Pancreas.—It is a long, flattened, conglomerate gland; it is about six inches in length, and is situated transversely across the posterior wall of the abdomen and behind the stomach.
Supra-Renal Capsulesare two small, yellowish and flattened bodies surmounting the kidneys, and inclining inwards and towards the vertebral column.
Kidneysare the secreting organs of the urine; they are situated in the lumbar region, and at each side of the vertebral column.
Pelvis.—The cavity of the pelvis is that portion of the great abdominal cavity which is included between the bones of the pelvis. The viscera of the pelvis in the male are the urinary bladder, prostrate gland and rectum.
Bladder.—It is a hollow, membranous viscus, triangular and flattened against the pubes when empty, ovoid when distended, and in front of and upon the rectum.
Circle of Willis.—The communications established between the anterior cerebral arteries in front and the internal cavities and posterior cerebral arteries behind, by the communicating arteries, constitute the remarkable vascular communication at the base of the brain called the circle of Willis.