49ers sign QB Adrian Martinez to active roster

The 49ers elevated quarterback Adrian Martinez from the practice squad on a temporary basis when Brock Purdy missed a couple of games earlier this year, but they made a different move ahead of Thursday night's game against the Rams. Martinez was signed to the active roster on Thursday afternoon. He'll serve as Mac Jones' backup with Purdy ruled out for the third time in four weeks because of a toe injury. Martinez has not appeared in a regular season game. The 49ers elevated wide receiver Malik Turner and defensive lineman Trevis Gipson for the game. Both players will return to the practice squad after the contest. Defensive lineman Jordan Jefferson was waived to create space for Martinez.