RENTON, Wash. >> The Seattle Seahawks may be without four starters for this week’s NFC West matchup against the Los Angeles Rams and two of the injuries could be long-term.

Running back Chris Carson will undergo surgery Tuesday for a severe high-ankle sprain suffered when his left leg was pinned in a pile in the fourth quarter of the Seahawks’ win over the Indianapolis Colts. Carson also has a small fracture just below his left knee, but the surgery will be to stabilize the ankle ligaments that were damaged, coach Pete Carroll said.

Carson led a long list of injury concerns for Seattle, which may also be without defensive end Cliff Avril, left tackle Rees Odhiambo and cornerback Jeremy Lane for Sunday’s meeting with the Rams.

Carson was placed on injured reserve Monday, although Carroll left open the possibility that Carson may return later in the season. Carson, a rookie seventh-round pick, had become the starting running back. The Seahawks will now go forward with Eddie Lacy and Thomas Rawls as their primary ball carriers.

Rawls was inactive Sunday, while Lacy had his most extensive work of the season with 52 yards on 11 carries.

“Thomas is really raring to go. We’re excited to get him to play and we love the way he plays,” Carroll said.

Carroll seemed most concerned about Avril and the neck injury he suffered in the first half. Avril was inadvertently kicked in the chin while trying to make a tackle from behind and his head snapped backward. Avril briefly lost feeling in his hands.

Carroll called the injury “serious stingers” and would not put a timeframe on when Avril may be able to return.

“It’s going to be a while for us to figure out what he’s got and take time to make sure we’ve got him clear and figured out,” Carroll said. “There are going to be some tests and stuff like that. I don’t have any timeline at all but we’re going to take care of him and make sure we take our time and do this really well to look after him.”

Avril is in his fifth season with the Seahawks. Seattle signed defensive lineman Quinton Jefferson off the Rams practice squad for additional depth with the uncertainty about Avril.

Odhiambo was released from the hospital Monday after being diagnosed with a bruised sternum. Odhiambo had breathing problems after the game and was tended to by medics in the locker room before being taken to a hospital for overnight observation.

Odhiambo was hit in the chest on an interception return in the second half. Carroll noted that Odhiambo was winded after getting hit, but the problems didn’t arise until after the game and medics needed to be called in to monitor his status.

“He just sucked it up and it kind of caught up with him after the game when he started to calm down,” Carroll said. “All the adrenaline wasn’t pumping and all. It was a really good effort by him to hang tough and play a really good football game like that.”

Lane suffered a groin strain on Seattle’s first defensive possession and spent the rest of the game as a spectator. The injury immediately thrust rookie Shaquill Griffin and Justin Coleman into more prominent roles. Both played very well, with Coleman stepping in front of a pass by Jacoby Brissett and returning it 28 yards for a touchdown for Seattle’s only first half TD against the Colts.

“We will count on those guys to do a nice job whether they are coming off the bench or starting,” Carroll said. “We have good depth and we’ve had a roster that we feel strongly about for some time now.”

NOTES: WR Doug Baldwin (groin) made it through Sunday’s game without issue after being questionable all week. Baldwin had three catches for 35 yards. … Seattle is hopeful RB C.J. Prosise (ankle) will be able to play against the Rams after being inactive last week. … Carroll did not say who would take Odhiambo’s spot at left tackle if he can’t play this week.