The Oakland Raiders put left guard Langston Walker on injured reserve Friday night and signed defensive tackle Anttaj Hawthorne from the practice squad to fill the roster spot. Walker, a fourth-year pro from California, underwent emergency surgery Oct. 25 to repair an internal hemorrhage sustained during a game against Buffalo two days earlier. He lost nearly a gallon of blood, then lost a significant amount of weight while recovering from the abdominal surgery. Hawthorne, a rookie from Wisconsin, was a sixth-round pick.