Henry Gray (18251861). Anatomy of the Human Body. 1918.
By means of these horizontal planes the abdomen is divided into three zones named from above, the subcostal, umbilical, and hypogastric zones. Each of these is further subdivided into three regions by the two sagittal planes, which are indicated on the surface by a right and a left lateral line drawn vertically through points halfway between the anterior superior iliac spines and the middle line. The middle region of the upper zone is called the epigastric, and the two lateral regions the right and left hypochondriac. The central region of the middle zone is the umbilical, and the two lateral regions the right and left lumbar. The middle region of the lower zone is the hypogastric or pubic, and the lateral are the right and left iliac or inguinal. The middle regions, viz., epigastric, umbilical, and pubic, can each be divided into right and left portions by the middle line. In the following description of the viscera the regions marked out by Addisons lines are those referred to.