The injuries Pittsburgh Steelers quarterback Ben Roethlisberger suffered to his throwing shoulder and ribs Monday night could be pretty significant, ones that could take a while to heal, a source close to the team said.

Roethlisberger was "extremely sore" Tuesday morning and "hurting pretty bad," the source said. After getting an MRI on Monday night, he went for another MRI on Tuesday.

A source confirmed to ESPN that Roethlisberger's rib and shoulder injuries occurred on the same play. The source said it remains unknown how long the quarterback might be unable to play with the injury to the front of his throwing shoulder.

At his news conference Tuesday, Steelers coach Mike Tomlin described Roethlisberger's shoulder injury as an "SC sprain." The exact terminolgy of Roesthlisberger's injury is a sternoclavicular dislocation, according to ESPN medical analyst Dr. Michael Kaplan. In this type of injury, the central end of the clavicle separates from the sternum (chestbone). An uncommon injury, it is extremely painful with strong ligament tearing (sprain). The usual treatment for the injury is conservative (no surgery, with rest, sling and rehab). Typically it takes several weeks until a quarterback is able to return to passing accurately and with sufficient velocity.

"Obviously, his injury puts his participation in the questionable category," Tomlin said.

Another Steelers source told ESPN that the team's staff was told: "proceed with (backup quarterback Byron (Leftwich). It doesn't look like you're going to have Ben this week. We're looking at next week as a possibility as of right now."

It seemed highly unusual and perhaps an indication of the seriousness of the injury that Roethlisberger went from the stadium to the hospital for an MRI on his right shoulder so late Monday night and remained there past midnight.

The Steelers have a short week to prepare for the archrival Baltimore Ravens, their opponents in two of the next three weeks and the AFC North leaders.

The Steelers have two veteran backup quarterbacks in Leftwich and Charlie Batch -- neither of whom has played much recently because of their own injuries, and because Roethlisberger has been so durable.

Of the 137 games the Steelers have played since Roethlisberger's first season of 2004, he has missed 14, including his four-game suspension in 2010. In that span, Pittsburgh is 86-37 (.699) with its star QB and 9-5 (.643) without, according to ESPN Stats & Information.

When asked Tuesday how the playbook would change if Leftwich had to start, Tomlin said, "I don't know that it does."