The false ribs are the five sets of ribs below the top seven true ribs. A rib is considered to be "false" if it has no direct attachment to the sternum, also known as the breast bone. Of these:
the first three (eighth, ninth, and tenth rib) have their cartilages attached to the cartilage of the rib above (costo-chondral):
the last two (eleventh rib and twelfth rib) are free at their anterior extremities and are termed floating ribs or vertebral ribs because they connect neither with the sternum nor with another rib. They are however attached to the backbone at their posterior extermities, like all the other ribs. These ribs are relatively small and delicate, and are capped by a cartilaginous tip.
The tenth rib attaches directly to the body of vertebra T10 instead of between vertebrae like the second through ninth ribs. Due to this direct attachment, vertebra T10 has a complete costal facet on its body. In several ethnic groups, most significantly the Japanese, the tenth rib is sometimes a floating rib, as it lacks a cartilaginous connection to the seventh rib.