'Buckwild' Star Anna Davis -- Head SLAMMED By Metal Lighting Rig

'Buckwild' star Anna Davis got the crap smacked out her this week in Kentucky ... by a MASSIVE pole covered in strobe lights -- and TMZ obtained the nerve-wracking video.

The smackdown happened at Whiskey Barrel Bar and Dance Thursday night in Richmond -- where Anna was hosting an event alongside the DJ ... and the rig above collapsed.

It's unclear why the structure fell -- but Anna says her neck, back and head have been "throbbing" since ... and she plans to see a doctor if the pain persists.