The San Francisco 49ers signed left guard Eric Heitmann to a four-year contract extension on Thursday. Heitmann, 25, was drafted by the 49ers in the seventh round of the 2002 draft and has played in 41 career games, including 36 starts. Last season, Heitmann started all 16 games and every snap at the left guard position. "We are excited about Eric Heitmann signing a four-year extension," head coach Mike Nolan said. "His dedication, discipline and hard work has helped to identify Eric as the type of player we want on our team. His youth, experience and versatility gives us flexibility on our offensive line." In other news, the 49ers released offensive tackle Scott Gragg. The 33-year- old played the first five years of his career with the New York Giants before moving to San Francisco for the next five seasons.