Devin McCourty suffers head injury

Patriots safety Devin McCourty left Sunday's game against the Baltimore Ravens with a head injury and will not return.

The injury occurred on a third-quarter collision with Ravens tight end Ed Dickson, whom McCourty tackled. McCourty was immediately shaken up and received attention on the field from medical personnel before heading to the locker room.

One of the team's co-captains on defense, McCourty has been a stalwart for the secondary this season, recording 66 tackles, one interception and two forced fumbles in 14 games started.

In his place, the Patriots turned to rookie Duron Harmon, a third-round pick out of Rutgers.

The Patriots have dealt with a number of injuries this season on defense, led by nose tackle Vince Wilfork and linebacker Jerod Mayo, who are both on injured reserve.