Pierna Vs Pata
Is it true that Pierna is only associated with humans and Pata with non-humans?
3 Answers
Usually, but not always. Pierna de cordero is leg of lamb, while sometimes you'll hear someone refer informally to a human leg as a pata.
Bear in mind that terms that normally apply to animals can be applied with insulting/joking intent to humans. The French say "Bas le pates" ("pates" is a cognate of "patas") which is best translated as "Get your paws of of me!" (or, with context, "... off of her/etc.").
As KevinB said, in "correct" Spanish that is true.
However, in some regions rural people refer to their limb as a "pata". In Mexico, a "pata salada" is the expression referring to a person from Puerto Vallarta.
Also, "pata" refers to the leg of a piece of furniture.