How many false ribs attach directly to the thoracic spine?

In the human ribcage, the classification of ribs includes true ribs, false ribs, and floating ribs. There are a total of 12 pairs of ribs extending from the thoracic vertebrae.

True ribs are the first seven pairs, which attach directly to the sternum via individual costal cartilages. The next three pairs, known as false ribs (the eighth, ninth, and tenth ribs), do not attach directly to the sternum. Instead, their cartilage connects to the cartilage of the ribs above them, forming a common connection to the sternum. These are often referred to as vertebrochondral ribs.

Furthermore, pairs eleven and twelve are classified as floating ribs because they do not attach to the sternum or to the cartilage of other ribs at all; they only attach posteriorly to the thoracic vertebrae.

Thus, when counting the false ribs that attach directly to the thoracic spine, we consider the eighth, ninth, and tenth pairs. There are exactly three pairs of false ribs, which connect indirectly to the sternum and attach posteriorly to the thoracic spine. This leads to the conclusion that the answer indicating a total of 10 false ribs is incorrect, as there are only three