Zenner was removed from Sunday's contest against the Bears in order to be evaluated for a head injury, Dave Birkett of the Detroit Free Press reports.
The Lions opted to sit Theo Riddick due to a wrist injury, opening the door for Zenner to pick up additional touches. Indeed, Zenner recorded seven rushes for 36 yards and two receptions for nine yards, yet Dwayne Washington led the way with 16 carries for 64 yards by game's end. If Zenner enters the concussion protocol, Washington would enter the upcoming week as the sole healthy running back in Detroit.