In the major injuries to key players, Week 10 of the NFL was marred by three start quarterbacks suffering head injuries:

* Philadelphia Eagles quarterback Michael Vick suffered a concussion during the first half of Sunday’s game against the Dallas Cowboys. Originally, the Eagles said he had been poked in the eye, but was also undergoing concussion tests, according to ESPN.com.

Vick was knocked on his back in the second quarter by linebacker Ernie Sims on an incomplete pass and was slow to get up. He headed for the locker room and rookie Nick Folesstarted warming up. Vick, however, may have been injured on the previous play when he was driven from behind head-first into the ground by tackle Jay Ratliff. Vick did not talk to reporters but appeared groggy in the locker room. Eagles coach Andy Reid said Vick would remain Philadelphia’s starting quarterback if healthy but acknowledged that the four-time Pro Bowler still must undergo tests.

Alex Smith of the San Francisco 49ers / Photo by Associated Press

* Minutes later on the West Coast, San Francisco 49ers starting quarterback Alex Smith suffered a concussion during the first half against the St. Louis Rams. The San Francisco Chronicle reported he may have suffered the injury earlier than it was thought.

Was it really the hit from Rams linebacker Jo-Lonn Dunbar that knocked Alex Smith from the game? That’s the assumption after Dunbar whacked Smith in the back of the helmet with a forearm following Smith’s 4-yard scramble. After the hit, which occurred on the third to last play of the first quarter, Smith went 5-for-5 for 56 yards. He also threw a 14-yard touchdown pass to Michael Crabtree after the play. Smith, on his final drive, was also sacked hard by Rams rookie defensive tackle Michael Brockers a few plays later. Smith also led with his head on a quarterback sneak on fourth-and-1 from the Rams’ 48 a few plays after the Brockers’ sack. The cumulative impact of all those plays could have caused the concussion.

* And later that night, Chicago Bears starter Jay Cutler went into the locker room after taking a hard hit to the head from Houston Texans linebacker Tim Dobbins prior to halftime and was relieved in the second half by veteran  Jason Campbell. The Chicago Tribune said that’s when the Bears announced Cutler had suffered a concussion.

As for Cutler’s status, Smith said it was too early to say if he would be available for next Monday night’s game at San Francisco. Smith did say that Cutler’s concussion symptoms seemed to lessen during the second half, and that Cutler wanted to go back in, but “that decision was made for him.”

Teammate Shea McClellin also suffered a concussion.

* In other injury news, Tampa Bay Buccaneers linebacker Quincy Black suffered a head and neck injury and then was carted off the field. ESPN.com reported that the Bucs are unsure if he will play again this season.

* The Buffalo Bills were trying to determine late Sunday if running back Fred Jackson suffered a concussion late in the game against the New England Patriots, according to BuffaloBills.com.

* Oakland Raiders free safety Matt Giordano and tight end Brandon Myers suffered a concussion (Myers’ second of the season)  against the Baltimore Ravens, according Comcast SportsNet Bay Area.

* And Denver Broncos defensive end Elvis Dumervil strained his left shoulder against the Carolina Panthers. The Denver Post reported that he will undergo an MRI on Monday and coach John Fox is worried it could be a serious injury.

– Bill Bradley, contributing editor