Batch broke his left wrist in Kansas City on Sunday, leaving second-year quarterback Dennis Dixon as the only backup to starter Ben Roethlisberger on the 53-man roster. Former Pitt quarterback Tyler Palko is on the practice squad.
Batch had surgery on Wednesday and was expected to be out two to four weeks.
Ramsey was cut by Tennessee last month. Bouman, a former Vikings backup, played briefly for Baltimore last season.