In trying to decide which mouse to get, I relaxed my hands and kind of hung them in the air over my desk, without twisting them in anticipation of a mouse. Tried to imagine being weightless. That position was probably 80 degrees off from what I would have to do to use an 'ordinary' mouse. So I thought, 'Hey, if the mouse is oriented the same as my hand would be in a relaxed state, maybe they're onto something'.
Anyway, it has several buttons, though I only use the three large ones. And the scrollwheel.