The Rib cage

The Rib cage

There are 12 pairs of ribs (Figure 9.9). Each individual rib is a thin, flat, curved bone that connects dorsally (at the back) to the vertebral column and, in most cases, ventrally (at the front) to the sternum. Because each rib has two separate articulation surfaces at its dorsal end, ribs are described as bicephalic ("two-headed").

The 12 pairs are grouped by how they attach ventrally:

• True ribs (vertebro-sternal ribs) — the first 7 pairs, attached dorsally to the thoracic vertebrae and ventrally, directly, to the sternum via hyaline cartilage.
• False ribs (vertebro-chondral ribs) — the 8th, 9th and 10th pairs, which do not reach the sternum directly but instead join the cartilage of the 7th rib.
• Floating ribs (vertebral ribs) — the 11th and 12th pairs, which have no ventral connection at all. …