Niners right tackle Anthony Davis has been ruled out for Thursday night’s game against the visiting Seahawks because of a concussion he sustained Nov. 16 and will be replaced in the starting lineup by Jonathan Martin for the seventh time in 12 games this season.

Martin will have an imposing assignment against Seattle defensive end Michael Bennett. The six-year veteran shares team-high honors with four sacks and his 48 quarterback pressures are tied for the most among 4-3 defensive ends, according to Pro Football Focus.

Derek Carrier (foot) is out and Vance McDonald (back) is questionable, leaving Vernon Davis as the 49ers’ only healthy tight end on the 53-man roster. McDonald, who missed last week’s win over Washington, was limited in practice this week.

Meanwhile, the Seahawks, who allowed a season-high seven sacks in a win over Arizona last week, will play their second straight game without center Max Unger (knee, ankle). Left guard James Carpenter (ankle), who has missed the past three games, is expected to play. Carpenter is listed as probable.

49ers

OUT: TE Derek Carrier (foot), T Anthony Davis (concussion), DT Glenn Dorsey (forearm)

QUESTIONABLE: CB Tramaine Brock (hamstring), WR Bruce Ellington (ankle), TE Vance McDonald (back)

PROBABLE: RB Frank Gore (knee), WR Brandon Lloyd (quadricep), DE Ray McDonald (knee), RB Bruce Miller (shoulder), S Eric Reid (ankle), DE Justin Smith (back), S Raymond Ventrone (groin)

SEAHAWKS

OUT: TE Cooper Helfet (ankle), LB Kevin Pierre-Louis (shoulder), C Max Unger (knee, ankle)

QUESTIONABLE: DE Demarcus Dobbs (knee), CB Jeremy Lane (glute)

PROBABLE: CB Marcus Burley (hamstring), G James Carpenter (ankle), WR Jermaine Kearse (ankle), RB Marshawn Lynch (back)

Twitter: @Eric_Branch