Seahawks quarterback Tarvaris Jackson was sidelined midway through the third quarter of Sunday's game against the Giants with a chest injury
Jackson gained 11 yards on a designed run, but came up holding his right shoulder and upper chest.
Seattle coach Pete Carroll said after the game that Jackson had a pectoral muscle problem and will undergo an MRI exam.
Jackson was replaced by Charlie Whitehurst, who led Seattle to a 36-25 victory.
Tarvaris Jackson Hurts Pectoral Muscle