Rams RB Jackson out Sunday

Nov 14, 2008 - 7:39 PM ST. LOUIS (Ticker) -- St. Louis Rams running back Steven Jackson has been ruled out for Sunday's game at San Francisco.

Jackson, who sat out Friday's practice, is scheduled to see a specialist in an attempt to learn why his strained right thigh muscle is not responding to treatment, the St. Louis Post-Dispatch reported on its website.

Jackson has 525 rushing yards, 259 receiving yards and four touchdowns this season.

Jackson injured the quad October 19 in a 34-14 win at Dallas. He then missed the Rams' Week Eight loss at New England.

Jackson returned for the 34-13 loss at home to the Arizona Cardinals, but managed only 17 yards on seven carries.

He was also inactive last weekend's 47-13 drubbing at the New York Jets.

Kenneth Darby started in Jackson's place against the Jets.

Backup Antonio Pittman will get the start on Sunday at San Francisco. Darby and Travis Minor are also expected to get some work in the backfield.