The team also signed center Bradley Vierling to the practice squad and waived linebacker Sidney Tarver from the practice squad.
McBath becomes the 29th player Jacksonville has placed on injured reserve this season.
Brown, a sixth-round draft pick by the Houston Texans in 2005, has played in 81 games with 62 starts over six seasons. He also spent time with the New York Giants and Detroit Lions. He hadn't been on an NFL roster in 2011.
Vierling spent the preseason with the Jaguars before he was placed on injured reserve in late August. He reached an injury settlement a few days later. He spent all of last season on Jacksonville's practice squad.
Copyright 2011 by The Associated Press