True ribs

Whether ribs are described as true or false relates to whether or not they are directly attached to the sternum.

The first seven pairs of ribs are true ribs, or fixed ribs, because they articulate directly with the sternum via cartilaginous extensions called costal cartilages. This is in contrast with the lower five pairs of ribs, which connect indirectly to the sternum or have no attachment to the sternum at all.