Running back Elijah Mitchell landed in the NFL's concussion protocol on Monday, one day after sustaining a head injury in the 49ers' 30-23 loss to the Seattle Seahawks.
Cornerback Emmanuel Moseley sustained a high ankle sprain, 49ers coach Kyle Shanahan said. Moseley is expected to miss "several weeks."
Special teams player Trenton Cannon was discharged from a Seattle hospital on Monday and was scheduled to return to the Bay Area after sustaining a concussion on the opening kickoff.
Mitchell was cleared to re-enter Sunday's game after Seattle defensive end Darrell Taylor hit him in the head. Mitchell was evaluated by an independent doctor on the sideline and was cleared to re-enter the game. He was also cleared in a postgame evaluation, 49ers coach Kyle Shanahan said.
"But he had symptoms this morning, so he's in the concussion protocol," Shanahan said on a conference call with Bay Area reporters.
A week ago, linebacker Marcell Harris was cleared after being evaluated for a head injury. But he was placed in the protocol the following day and did not suit up to face the Seahawks.
"The evaluation we do is the same the whole league does," Shanahan said. "It's stuff that happens all over. I know if you come in the next day with a headache, you automatically go into the protocol."
The 49ers expect linebacker Fred Warner (hamstring) to return to practice on Wednesday and be available to face the Cincinnati Bengals on Sunday.
Wide receiver Deebo Samuel (groin) remains day to day, but Shanahan said he is hoping to get him back this week, too.
In addition. running back Jeff Wilson Jr.'s surgically repaired knee "flared up" on him during the game. He played just two offensive snaps.
Cannon's injury was particularly scary, as he remained on the turf for several minutes after a collision on the opening kickoff. Cannon was placed on a stretcher and transported via ambulance to a local hospital, where he remained overnight for observation.
Shanahan said after the game that Cannon sustained a concussion and no other physical issues.
"Concussions are very concerning, but all the stuff you’re really worried about, he’s cleared," Shanahan said. "He remembers it all."
Moseley played just nine defensive snaps before sustaining an injury to his right ankle. Rookie Deommodore Lenoir replaced him and struggled in coverage as he played the remainder of the first half.
The 49ers went with veteran cornerback Dontae Johnson at the beginning of the second half. Shanahan said third-round pick Ambry Thomas has shown improvement in practices and could be in the mix to compete for playing time.