abdomen defined in 1939 yearabdomen - Abdomen;
abdomen - Cavity of the body lying between the large horizontal muscle called the diaphragm and the bones and muscles forming the pelvis. The principal organs contained in the abdomen are the stomach and intestines, liver, spleen, pancreas, kidneys and bladder, and in both sexes organs of reproduction. Anatomists divide the surface of the abdomen into nine regions by means of two horizontal and two vertical lines, the three central regions being termed, from above downwards, the epigastric, umbilical and hypogastric, and those at the sides, the right or left hypochondriac, lumbar, and iliac.
In the lower phyla, or orders, of the animal kingdom there is no persistent distinction between the abdomen and the thorax or chest, though the general body cavity is often composed of two divisions. It may be regarded as beginning with the arthropoda. In the insects and their allies the abdomen, generally divided from the thorax by a narrow constriction, is usually segmented or divided externally into rings, which may bear appendages, as in the Crustacea. In the human species and in the anthropoids an erect habit has caused the abdomen to become the lower part of the body cavity. Commonly known as the belly, it is enclosed by a muscular body wall, lined by a smooth membrane known as the peritoneum, which facilitates the peristaltic movements of the viscera. See Anatomy; Liver; Stomach, etc.
pictures for abdomen
abdomen defined in 1951 yearabdomen - abdomen;
abdomen - In vertebrates: region of the body containing the viscera other than heart and lungs (i.e. intestine, liver, kidneys, etc.); in mammals, but not in other vertebrates, bounded anteriorly by diaphragm. In arthropods: posterior group of segments similar to each other.
near abdomen in Knolik
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