Thornhill (calf) was a limited participant in Thursday's practice, Daniel Oyefusi of ESPN.com reports.
Thornhill was sidelined for Week 13 against the Broncos due to a calf injury, and he was estimated as a DNP on Wednesday's injury report. Thornhill's return to practice Thursday indicates he is progressing through his recovery, and if he's able to practice Friday, he'll give himself a chance to play against the Steelers on Sunday.