The game was delayed several minutes as Boychuk was attended to by medical and training staff on the ice before being wheeled off the ice.
Bruins general manager Peter Chiarelli later issued a statement that said Boychuk was taken to Montreal General Hospital for observation.
"Before he was transported to hospital he was able to demonstrate movement in all his extremities," Chiarelli said.
There was no immediate word on the nature of the injury.
Pacioretty was given a two-minute penalty for boarding at 4:28 of the first period.
Boychuk had chased the puck into the Canadiens' end of the rink. The hit into the end boards to the right of goalie Carey Price did not look particularly hard, but Boychuk's face struck the top of the boards and he fell to the ice.
He was on his knees breathing heavily for several minutes before trainers got him onto his back and onto the stretcher.
Pacioretty was on the receiving end of a hit from Boston's Zdeno Chara on March 8, 2011 that left the Canadiens left winger with a concussion and a fractured vertebrae in his neck.