Penix suffered a knee injury during Sunday's contest against the Panthers, Tori McElhaney of the Falcons' official site reports.
Penix completed 13 of 16 passes for 175 yards, no touchdowns and no interceptions while rushing one time for nine yards at the time he departed in the third quarter after getting twisted to the ground on an incompletion. Kirk Cousins will direct the Falcons offense for as long as Penix is sidelined.