The anterior surface of the abdomen is divided into four quadrants by two intersecting lines, one extending vertically from the xiphoid, through the umbilicus to the symphysis pubis耻骨联合)and the other extending horizontally across the abdomen at the level of the umbilicusThe anterior surface of the abdomen is divided into four quadrants by two intersecting lines, one extending vertically from the xiphoid, through the umbilicus, to the symphysis pubis (耻骨联合)and the other extending horizontally across the abdomen at the level of the umbilicus