Starting linebackers Hau'oli Kikaha (ankle) and Dannell Ellerbe (hip), backup linebacker Ramon Humber (hamstring) and backup cornerback Damian Swann (concussion) all missed practice for the second straight day, leaving their status in doubt for Sunday's game against the Tennessee Titans.
Quarterback Luke McCown also missed Thursday's practice with a back injury after practicing fully Wednesday.
Armstead seems likely to play since he has played every snap the last two games despite missing practice time early in the week after returning from a knee injury.
Snead's status remains unclear since he's dealing with a new injury. He played the full game last Sunday against the New York Giants but missed practice Wednesday with an unspecified knee injury. It was a good sign that Snead was able to return to team drills Thursday, even on a limited basis.
Players' official injury designations will be announced Friday afternoon.