Weirdly flexible head/neck? (cockatiel)

[cholla46]

Today as I was putting my cockatiel to bed, he put his head next the bars so he could get his usual head scratch. Now I know birds have flexible necks in a lot of ways, but I swear he nearly turned his head ALL the way around- like, his beak was facing the ceiling, eyes were where beak would be...he calmly turned his head back to normal one the head scratch moved to a different spot and just kind of went about his normal business. I thought maybe this was a common thing, but when I googled it, I didn't see anything specifically about it, barring one Yahoo!answers about a bird whose head was turned around the other direction permanently o.O and since it's pretty bizarre, I kind of expected to find a bunch of "look at this bird with its head turned upside down!!1" posts...and I didn't. So, is this abnormal? If so, is it dangerous? He's acting normal and healthy otherwise, and he can clearly move his neck to and from this position at will...it just seems like an awfully extreme angle, even for a head scratch, lol.
Any advice would be appreciated, thanks in advance!

[Wolf]

My advice would be to relax and enjoy this behavior. Although I don't have cockatiels, most of my other birds will turn their heads completely upside down when I scratch their heads, they seem to really enjoy having the bars of their lower jaw scratched just behind the beak. The most comical thing that any of my birds do is a parrotlet that scratches its head and face by stepping over it's wing.
Relax and enjoy turning their head over is perfectly normal.

[Pajarita]

Yes, it is a bit unsettling when you first see them do the 'exorcist thing', isn't it? But it's normal. Birds have more vertebras in the neck than we do and can achieve a much larger range of movement (some species, like the owls, rotate their heads up to 270 degrees around!).

[cholla46]

Thanks so much! I've had a 'tiel before, but he wasn't nearly as enthusiastic about head scratches, so I'd never seen this before. I knew birds had pretty flexible necks, and he's turned at some pretty weird angles before, just not so close to all the way around haha.