ESPN's Chris Fowler first reported Speight's injury at the top of ABC's Saturday night broadcast of Michigan State's 14-10 upset of Michigan in Ann Arbor. "Wilton Speight ... he is out, probably for the season," Fowler said. "He has three broken vertebrae, he told us."
Speight was injured during the first quarter against Purdue on Sept. 23 when he was hit awkwardly by a defender while on the ground.
Although Speight likely will be out for the rest of the season, he will be re-evaluated six to eight weeks after the injury happened. It is unknown whether surgery will be an option or the injury will heal on its own.
Speight had completed 54.3 percent of his passes on the season for 581 yards and three touchdowns before the injury. He was replaced by backup John O'Korn, who helped the Wolverines rally to a 28-10 win against the Boilermakers.
O'Korn started against Michigan State, going 16-for-35 for 198 yards with three interceptions.