Why would their legs still functions to walk around with then? That would be picking and choosing which muscles still function. I would imagine all of them would be functioning until destroyed. We've seen zombies breathe and bleed on the show so its not all that far fetched to assume everything is running at some capacity until something gets in the way of that - damage or rot or whatever. Those are basic, non conscious actions the body naturally does. As zombies are minimal thinkers at best, I would think those same non conscious actions we've had since birth would still function as before. Obviously there is
something different going on with the body as it died and reanimated, but I just don't see things being shut off randomly. If they don't need to breathe to function, then maybe the lungs would just stop taking in air. If there isn't blood to pump, maybe the heart would stop beating. But as long as their isn't some outside influence, it would seem reasonable to assume everything would continue to run as normal. We know they can still hear. And we know they can still see, at least until their eyes are removed or destroyed. Those are basic, non conscious actions we've always had (any disabilities excluded, of course)
Funny enough, at SDCC there was a girl in a wheelchair that asked why we don't see any zombies with disabilities. Gimple was clever enough to point out some stuff at the retirement home episode that may have been disabled zombies, but I think they were all just too polite to admit that people with disabilities would likely be the first to go as they'd prove to be an easier meal for the zombies.
the idea of ,wolverine zombies, with regenerative cells that don't need blood is good for a fantasy setting 
