Thin skin??

I have no idea even how to google this...

This morning my brother called, and as we were talking I accidentally dropped the portable phone. In the process, it hit the back of my hand and took out a chunk of skin the size of a dime, or maybe even a nickel.

Now, the phone only dropped a couple of feet and it doesn't weigh that much, so it must be about my skin.

Anyone have any clues?