According to the abdominal tetrad, the lower abdomen refers to the part below the horizontal line of the navel; according to the abdominal tetrad, the lower abdomen refers to the part below the line of the right and left anterior superior iliac spines. 1. Abdominal quadrature: usually refers to the horizontal and vertical lines of the navel to the abdomen is divided into four zones, namely, the right upper abdominal area, the right lower abdominal area, the left upper abdominal area, the left lower abdominal area, and the lower abdomen that is below the level of the navel. 2. Nine points of the abdomen: usually refers to the use of two horizontal lines and two vertical lines will be divided into nine areas of the abdomen, where the upper horizontal line for the lowest point of the rib cage on both sides of the line, the lower horizontal line for the two sides of the anterior superior iliac spine of the line, which can be divided into the upper abdomen, abdomen and lower abdomen, and the lower abdomen, that is, the right and left iliac spine of the following part of the line.