49ers injury notes and updates: Shanahan on Nick Mullens’ possible Tommy John surgery, Jimmy Garoppolo, Richard Sherman

49ers head coach Kyle Shanahan gave some injury-related updates on quarterbacks Jimmy Garoppolo and Nick Mullens and cornerback Richard Sherman Thursday, delivering some good news on Garoppolo and some not-so-good news on Mullens and Sherman.

Shanahan gave his thoughts on how Garoppolo has looked since the team opened his 21-day practice window to return from injured reserve earlier this week. Garoppolo has been on injured reserve since November 5 due to an ankle injury and may not play again this season, but the early prognosis on where he is at the moment sounds positive.

"I thought he looked good," Shanahan told reporters Thursday. "Just having him out there throwing again -- always when Jimmy's out there throwing it's usually pretty impressive. We didn't move him around much because we are trying to be safe with him. But he looked great. He looked like Jimmy."

But while Garoppolo is on the mend, Mullens could be in the beginning phases of a rehab process that will last for months after he hurt his elbow in the 49ers' Week 15 loss to the Dallas Cowboys. There's been talk that Mullens will need Tommy John surgery to repair his injury, which Shanahan wasn't ready to confirm on Thursday, but he does expect that his quarterback will be sidelined for an extended period of time.

"I think he's going down to have them look at it," Shanahan said. "I'd be probably surprised if not. It's going to be a long recovery regardless, whether he gets surgery or not. But it's not a hundred percent sure. They're going to wait to decide on that once the swelling's gone down."

Mullens, who has been starting in place of Garoppolo, left the 41-33 loss to Dallas last Sunday and was replaced by backup C.J. Beathard after suffering the injury. Beathard will start for the 49ers when the team faces the Arizona Cardinals on Saturday.

"I was throwing the football, and they hit my hand, and I jammed my elbow a little bit," Mullens said of the injury. "So, I figured it was best for the team for somebody who could throw the football to get in the game."

Also out for the 49ers this week will be Sherman, who aggravated a calf injury that cost him to miss nine games earlier in the year. Sherman returned for the 49ers to play in each of the last four games, but the 49ers may need to prepare to be without him the rest of the way.

"I was surprised when he did come back because I knew how much it was bothering him throughout the year," Shanahan said. "I think he got well enough for him to come out and play on it and help us out, but I don't think by any means he was feeling 100 percent."

Shanahan added, "You could tell it's been wearing on him a little bit. He tried to give it to us this week and tried to go, but I had a pretty good idea it was going to be tough for him, and that's the way this week ended up."

Sherman is slated to become an unrestricted free agent after the season, while Mullens is due for restricted free agency. Whether or not they've played their final games with the 49ers remains to be seen.