(1.39)

In this section we’ll look at the musculo-skeletal structures that surround the abdomen. We’ll look first at the bones that lie above, behind, and below the abdominal cavity. Then we’ll see the layers of muscle and tendon that form the wall of the abdomen. After that we’ll take a detailed look at the lowest part of the abdominal wall, the inguinal region. Lastly we’ll look at the principal blood vessels and nerves of the region.

We’ll look at the abdomen in this tape as a container, as we did with the Thorax. We’ll look at what it contains in Volume Five of this Atlas.

Let’s start with the bones that we’re concerned with: the lower ribs, the lumbar vertebrae, and the bones of the pelvis. We’re familiar with the rib cage already. The lower edge of the rib cage, formed by th elast three ribs and the costal arch, is called the costal margin

Just above the costal margin on the inside, the diaphragm arises, as we’ve already seen. The diaphragm forms the upper limit of the abdominal cavity. Because of the shape of the diaphragm, the upper part of the abdominal cavity extends a long way above the the costal margin.

The rib cage is also a major site of attchment for abdominal wall muscles, as we began to see in the last section.

The lumbar vertebrae provide the foundation for the posterior part of the abdominal wall. The massive bodies of the vertebrae project forward into the abdominal cavity.