Devils coach Peter DeBoer announced the lineup additions during his meeting with the media at Wells Fargo Center after the team's morning skate.
Zajac has been out the past two games with a sprained right ankle and Volchenkov missed one game with a lower-body injury. Defenseman Peter Harrold, who was placed on injured reserve retroactive to Oct. 22, will replace Mark Fayne in the lineup. Patrik Elias was placed on IR to make room for Harrold's return.
The Devils have been held without a goal for two straight games. If the team goes 10:13 without scoring a goal against the Flyers, it will mark the second longest goal-less streak in franchise history (159:18).
The Devils aren't the only team having issues with scoring. The Flyers rank last in the League with a 1.57 goals-per-game average; the Devils rank No. 28 (1.86). Flyers captain Claude Giroux has yet to score for his team and has a minus-10 rating.
"We need to stay positive," Giroux told reporters Wednesday. "We are a good team. When we start believing it, when we start playing like it, we'll be a dangerous team."
The Flyers have been anything but dangerous on offense in 14 games this season. The team has four goals in the past four games (1-2-1) and is 15th in the Eastern Conference (4-9-1, nine points).
"I really believe that when we start believing that we're a good team, that's when we're going to start winning games," Giroux said. "We're not convinced that we are right now."
Flyers coach Craig Berube reportedly will start Ray Emery in net. Emery, who earned the shutout against the Devils just five days ago, is 6-3-2 with two shutouts, a 1.90 goals-against average and .931 save percentage in 11 career games against New Jersey.
Here's how the lineups might look Thursday:
Injured: Steve Downie (concussion)