According to Chris Mortensen of ESPN, Bengals punter Kevin Huber not only suffered a broken jaw last night but also a cracked vertebrae in his neck.
Bengals punter Kevin Huber not only suffered broken jaw but also a cracked vertebrae in his neck on block by Steelers' Gavin. Headed to IR.
— Chris Mortensen (@mortreport) December 16, 2013 
This is the hit that Huber suffered the injury on last night as Steelers punt returner Antonio Brown was running a punt back. If you look closely at Huber’s head at the time of impact, you notice that Gavin’s helmet was able to slip under Huber’s helmet just a tiny bit, possibly being what caused his jaw to fracture.