j. Regions of the Abdomen.
(1) The abdomen is that portion of the body that lies between the thorax and
the pelvis. It consists of a large cavity, separated from the thoracic cavity by the
diaphragm, bounded by muscles and fascia, and partially lined with a serous membrane
called the peritoneum.
(2) For purposes of description, the abdomen is divided into nine regions
(figure 1-7) by means of two horizontal and two vertical lines. The upper horizontal line
passes through the tenth costal cartilage inferiorly. The lower line passes through the
level of the iliac tubercle. Each vertical line passes through the midpoint of a line drawn
from the anterior superior iliac spine to the symphysis pubis.
Figure 1-7. Regions of the abdomen.