нога = leg or foot? How do you distinguish?

[david-us.livejournal.com]

How do Russians make the distinction between "leg" and "foot"?

Yes, I understand there are many standard phrases where it is understood. But that isn't always the case.

When babies are just learning to talk a common "game" to play with them is to say:

"Touch mommy's nose." 

"Now touch mommy's ear."

"Where are mommy's lips?"

"Where are mommy's eyes?"

"Can you find mommy's chin?"

Babies love this game and it is very instructive. They are playing and learning - all at the same time.

But what does the poor baby do when you ask ...

"Где нога мамы?" or "Где рука мамы?"

Why don't Russians have separate word for leg/foot and arm/hand?

If you want somebody to wave their hand - how do you get them to do that without it being misinterpreted as "Wave your arm?"