A couple of vertebra of the human spine has (beside their position names C1-C7, Th1-Th12 etc), got a special name e.g.atlas, axis and vertebra prominens (C7), because of its function or appearence. The rest only have the name of their position.
Can it be that the rest of the vertebrae somewhere during the history have lost their own names? Why shouldn't a L5 have had it's own name? It's typical enough.
Do anybody know something about this topic?