Henderson was apparently hurt in Sunday's game at Indianapolis. Coach Leslie Frazier said the team had "no indications" he had a head injury at the time. Henderson didn't complain about symptoms until Wednesday, when he told Frazier he "did not feel right."
Henderson underwent some of the required post-concussion tests on Thursday but has more of them to pass before he can be cleared to return to the field. If he can't play on Sunday against San Francisco, Marvin Mitchell would take his place at the weak side spot.
Middle linebacker Jasper Brinkley, who normally comes out in the nickel defense, would take Henderson's spot in that package.