Thornhill (calf) was placed on injured reserve Wednesday.
Thornhill suffered the injury late in Sunday's loss to the Cowboys, according to Daniel Oyefusi of ESPN.com, who relays that head coach Kevin Stefanski stated the Virginia product does have the potential to return this season. It's a tough blow to the Browns who will now be without their starting free safety for at least the next four weeks and are dealing with multiple injuries to their defense. Ronnie Hickman is expected to step up now in Thonrhill's stead.