Pathfinder dragon breath biology

[JET73L]

Do they breathe from their mouths or, like D&D dragons, from their stomachs? Either way, it's shaped magic energy, not an actual chemical/chemical reaction, right? (Definitely not an "exhale gas from inside torso, activate the fire/cold/electricity in the mouth" thing like in How to Train Your Dragon?)

[Psyren]

It's still magic in PF (because Su tag) and a dragon in an AMF or dead magic area will be unable to use it.

Generally the breath weapon does not exist anywhere within the dragon. Otherwise a blue dragon would deal electricity damage to any swallowed prey, or a brass dragon would be able to put creatures in its stomach to sleep etc. The breath weapon functions just as it says it does, typically as a cone or line originating from the dragon's mouth and extending some area outward.

[JET73L]

Hm. Is that a ruling somewhere, or an interpretation? (If it's a ruling, yay! That works perfectly with something I was thinking about doing that's no longer completely suicidal!)