Michael Vick and Alex Smith were knocked out of their games when each sustained a concussion in the first half, leaving both the Eagles and 49ers unsure of their quarterback's status for next week's games.

Vick was hit by Cowboys linebacker Ernie Sims on an incomplete pass and was slow to get up early in the second quarter of Philadelphia's 38-23 loss to Dallas. Vick headed for the locker room and was replaced by Nick Foles with the game tied 7-7.

Vick threw a 2-yard touchdown pass to Riley Cooper in the first quarter.

Smith scrambled and started to slide before turning his back late, and Rams linebacker Jo-Lonn Dunbar barreled into his neck area with 1:10 left in the first quarter of a 24-24 tie against St. Louis. Smith briefly grabbed his facemask and grimaced but stayed in the game, throwing a 14-yard touchdown pass to Michael Crabtree in the second quarter.

Colin Kaepernick replaced Smith on San Francisco's next possession. Smith sat on the bench next to 49ers athletic trainer Jeff Ferguson and other trainers before walking to the locker room just before halftime.

The 2005 No. 1 overall draft pick, who was 7 for 8 for 72 yards and the touchdown, started every game for the 49ers last season.

Tampa Bay linebacker Quincy Black was hospitalized for observation of a neck injury after being carted off the field during the third quarter of the Buccaneers' 34-24 victory over San Diego.

Black was injured tackling running back Ryan Mathews for a 1-yard loss, remaining on the ground with just under 4 minutes left in the quarter. The Bucs did not release specifics about the injury, but coach Greg Schiano said the sixth-year pro is expected to be OK.

Trainers worked over Black for several minutes before immobilizing his neck and back on a stretcher.

"He's at the hospital for observation. We think he's going to be OK, but he's got to work through some things," Schiano said after the game.

Schiano was the head coach at Rutgers when former Scarlet Knights player Eric LeGrand broke two vertebrae and suffered a serious spinal cord injury in October 2010 during a kickoff return against Army. He said thoughts of the paralyzed defensive lineman went through his mind when Black remained on the ground.

"I thought about it immediately. When a guy goes down and he's still," Schiano said before stopping abruptly. "The good thing was Quincy immediately moved his right arm, so that was a relief."

Several players on both teams kneeled and prayed while Black received assistance on the field.

Buccaneers cornerback Eric Wright left the game in the first half with an ankle injury and did not return.

Bears quarterback Jay Cutler left Chicago's 13-6 loss to the Houston Texans because of a concussion. A scrambling Cutler took a helmet-to-helmet hit from Tim Dobbins after unleashing a pass on third down at midfield late in the first half Sunday night.

There were offsetting penalties on the play. Cutler got called for an illegal forward pass because he was beyond the line of scrimmage and then got drilled by Dobbins, who was called for unnecessary roughness.

Cutler stayed in for the rest of the half, but Jason Campbell came out to start the third quarter.

The Bears also lost defensive end Shea McClellin because of a concussion in the game's opening minutes.

Giants receiver Domenik Hixon suffered an ankle injury in the first quarter of New York's 31-13 loss to Cincinnati and didn't return. The Giants initially thought he might return but announced in the second half that he was done for the day. There was no indication of the severity of his injury.

Lions cornerback Chris Houston said he'll "be OK" after leaving Detroit's 34-24 loss to Minnesota in the fourth quarter on a cart. He hurt his ankle and said a Vikings lineman intentionally landed with both knees on his lower leg. The Lions also lost defensive end Cliff Avril in the third quarter to a concussion.

Broncos defensive end Elvis Dumervil left Denver's 36-14 win over Carolina midway through the second quarter with a left shoulder injury. Dumervil, who has six sacks this season, had two tackles and a forced fumble before he was replaced by Robert Ayers.

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