Palmer, who is in the concussion protocol, was not at the open part of Arizona’s practice Wednesday. He also didn’t practice on Monday or Tuesday. He was at the team’s facility, however, attending meetings and undergoing tests.
Drew Stanton will start Thursday night’s game in Palmer’s place. Zac Dysert, who was promoted from the practice squad to the active roster on Tuesday, will back up Stanton.
Stanton’s last start came in Week 15 of the 2014 season, when Palmer was out with a torn ACL.
Palmer suffered the injury with 5 minutes, 40 seconds left in the Cardinals’ 17-13 loss to the Los Angeles Rams on Sunday. On the play, a sack was split by Rams defensive tackle Aaron Donald and defensive end Eugene Sims, and Palmer’s head appeared to hit the turf. He was wobbly after being helped up by teammates and was met by team doctors and trainers at the sideline as he came off the field.
Stanton threw two interceptions Sunday after replacing the injured Palmer.
ESPN’s Josh Weinfuss contributed to this report.