Head injuries are scary. It's the reason the NFL has made such a big deal about trying to prevent them from happening in recent years. They don't want guys suffering from things like memory loss as a result of big hits.

But no matter how hard they try, they can't prevent all head injuries from happening. So there are still going to be guys who suffer them during games. And last night, Raiders quarterback Terrelle Pryor found that out the hard way when he sustained a concussion towards the end of the Raiders/Broncos game. The hit that he took from Denver linebacker Wesley Woodyard that caused the concussion didn't look all that devastating. But as he explained on Twitter today, Pryor doesn't even remember it.

Scary stuff. Think about that tweet the next time you get pissed off about a referee throwing a flag for a hard hit.

RELATED: Head Cases: The Worst Concussion Moments in Sports

[via Larry Brown Sports]