what is a abdomen

The abdomen is the part of the body between the thorax (chest) and pelvis, in humans and other vertebrates. It is the front part of the abdominal segment of the torso and is enclosed by the abdominal muscles at the front and to the sides, and by part of the vertebral column at the back. The area occupied by the abdomen is called the abdominal cavity, which is continuous with, and above, the pelvic cavity. The abdomen contains many vital organs, including the stomach, small intestine, large intestine, liver, spleen, gallbladder, pancreas, uterus, and kidneys. The alimentary tract in the abdomen consists of most of the digestive tract, where most of the absorption and digestion of food occurs. The abdomen also contains an extensive membrane called the peritoneum. Clinically, the abdomen is roughly divided into nine regions by two sagittal planes from the midclavicular lines to the mid inguinal lines, and two transverse planes, one at the subcostal line and one at the iliac tubercles. The umbilicus serves as the center of the nine regions.