Caer de bruces

[poli]

This means to fall on your face.
Is there a similar term for: to fall on your back?

[irmamar]

Caerse de espaldas (when someone is amazed). Does it have the same use in English?

[poli]

Caerse de espaldas (when someone is amazed). Does it have the same use in English?
El modismos exacto--no.
Pero hay dichos con fall que expresan sorpresa.

ejemplo: I nearly fell off my chair.
I nearly fell over.

[hermit]

I guess it wouldn't be stretching the point to say "The news knocked me flat.", (the inference being "...on my back.")