PinkyCause Horowitz's pinky was like the only one that was completely independent from his fourth out of pretty much every pianist I've seen - if you've seen any videos of him you might have noticed that even when his fourth and third are playing, he's able to curl the fifth up right under his palm, something that no one else can do.
actually I do that all the time. Teachers hate it when I do it. I thought it was a bad thing.
You guys can split the brain, I'll take the nervous system.