What you can do with your fingers isn't just about size and speed. Hand anatomies are *not* all the same - the ligaments divide in different places for different people, which makes for intrinsically different degrees of strength or independence of movement. This can be a real problem in classical piano music where the composer had hands with different capabilities from the pianist who's just trying to play the thing.

There is quite a bit on this at Richard Beauchamp's site, musicandhealth.co.uk. It was Richard who told me this stuff - he's a classical pianist and piano teacher who has made a special study of hand anatomy. He once had to use his expertise the hard way after getting his hand smashed to a a pulp in an accident; it works fine now, but mainly because he got it fixed up by an expert surgeon who was prepared to listen to what Richard had to say about what he wanted done.

My thing is mouth anatomy. I have a cleft lip and palate, and have had surgery that took a piece of lower lip out, rotated it 180 degrees, and implanted it in my upper lip, so I have scars on both (not very visible, see the photos on my website and I doubt you'll spot them). But I've managed to play the flute, clarinet and saxophone despite that. The higher pressures needed for reeds require me to bung up an internal leak in my palate with a postage-stamp-sized piece of denture fixative sheet, something I only realized existed a few years ago.