The moves came a day after the Flyers learned that forward Jeff Carter would miss six weeks with a broken left ankle.
Nedved, 34, started the season with the Flyers but was demoted after going scoreless in six games. He recorded four goals with four assists in seven games for the Phantoms.
Ellison, 22, has a goal and an assist in one game for the Phantoms after missing 11 contests while recovering from abdominal surgery.
Potulny, 22, has one goal and two assists in seven games for the Phantoms.
Grenier, 26, is scoreless with 16 penalty minutes in nine games for the Phantoms.