BOSTON — The Bruins’ second line shined on Thursday in Boston’s 5-2 win over the St. Louis Blues.

Pavel Zacha scored twice — including a buzzer-beater on the power play in the second period — and Viktor Arvidsson had two points in the victory. While Casey Mittelstadt didn’t have a point, he did have three shots on goal.

“Before the game we said, as a line, we need to be a little bit better than we were in Detroit. And I think we showed that, especially after the first period,” Zacha said. “It was a better game than last one, for sure.”

It was a positive development for Boston. Both Mittelstadt and Arvidsson spent time on injured reserve and returned recently. Arvidsson’s goal was his first since Nov. 15 when he suffered a lower-body injury against the Montreal Canadiens.

“We see each other well on the ice. … It’s pretty natural with us,” Zacha said of chemistry with Arvidsson.

For Arvidsson, who had a two-point night, he knows a strong game is a step in the right direction for his line to get back to their identity they had to start the season.

“We’re getting there,” Arvidsson said. “I think we’re getting back into the chemistry and reading off each other, creating changes. I think we’re doing a good job.”

Arvidsson was playing some of his best hockey before his injury landed him on injured reserve, but he’s been able to slot back into the lineup and quickly make an impact.

Especially with David Pastrnak dealing with an undisclosed injury, the Bruins need to rely on other forwards to step up. That kind of next-man-up-mentality was on display Thursday when six players had multi-point games.