Murphy said he was hurt when he was kneed in the helmet by teammate Nnamdi Asomugha during practice Friday. Murphy had a bad headache and missed practice Saturday.
Murphy is being counted on heavily in his second year in the NFL. He led all Raiders wideouts with 34 catches for 521 yards and four touchdowns as a rookie last season.
Wide receiver Chaz Schilens also sat out practice Saturday with a sore left foot, according to the San Francisco Chronicle.
According to Cable, Schilens is "improving, just want to continue, just want to not have any soreness."
Schilens' foot was operated on twice in the past year. The third-year pro has appeared in 24 games for the Raiders with 44 receptions for 591 yards and four touchdowns.
The Associated Press contributed to this report.