While tight end Julius Thomas remained a spectator Friday, working through left ankle issues, the Broncos received a boost as Brandon Marshall was cleared to participate by an independent doctor.

The linebacker began the concussion protocol last Sunday, and gradually eased back into activity. He is expected to start Sunday at Kansas City, a huge lift given his performance this season and the inexperienced reserves behind him on the depth chart.

Marshall leads the Broncos with 94 tackles in 11 games, incuding 10 starts. He also wears the audio helmet, communicating with the coaches and relaying the defensive signals. He was hurt in the fourth quarter against the Dolphins, leaving the Broncos leaning heavily on rookie Lamin Barrow, who participated in a season-high 21 plays.

Barrow is improving, but he and rookie Corey Nelson are not the same as Marshall, an emerging star who brings energy and leadership to the defense.

Thomas, meanwhile, remains limited. He hurt his left ankle in St. Louis 12 days ago when running back C.J. Anderson rolled up onto him. His status remains uncertain for Sunday, but after similar participation last week the Broncos made Thomas inactive for the Dolphins game.

Cornerback Aqib Talib will likely be a game-time decision. He participated in defensive drills Friday as he pushes through a hamstring injury that limited him to 17 plays against the Dolphins. His backup, Kayvon Webster, has not practiced this week because of a dislocated shoulder.

Run for it. Offensive coordinator Adam Gase remained uncertain whether the Broncos would improve their ground game last Sunday despite solid practices. His mind changed in the first quarter.

“I think it helped when we got into a good rhythm early,” Gase said. “I think after the first or second drive, they were like, ‘Hey, we’re feeling pretty good about what you’re calling. Stay with it.’ “

Footnotes. Running back Ronnie Hillman has started physical activity as he makes progress with a foot injury suffered against the Raiders on Nov. 9. … Practice squad quarterback Zac Dysert was excused from practice because of an illness.

Troy E. Renck: trenck@denverpost.com or twitter.com/troyrenck