text: is the fingernail an extension of the bone? if so/not, can you justify? i've read in some old trivia science cards that fingernails are in fact extensions of the bone, but research has led me to believe that fingernails are only connected to the bone through fibers called "hyponychium."  i wonder, does this justify that they are bone extensions, flesh extensions, or other? your finger nail is made up of keratin, a protien.  the same as your hair.  it is not bone. it is more a form of harden skin.  it helps protects your finger tips from damage. the matrix of the nail, lies under the skin still, and if that doesn't get damamged then your nails will continue to grow. if you would like to know more than try going to a cosemtolgy/manucurist web site.