Although all ribs articulate with the vertebral column, only the costal cartilages of the upper seven ribs, known as true ribs, articulate directly with the sternum. The remaining five pairs of ribs are false ribs:
The costal cartilages of ribs VIII to X articulate anteriorly with the costal cartilages of the ribs above.
Ribs XI and XII have no anterior connection with other ribs or with the sternum and are often called floating ribs.