The Steelers placed Henderson (neck) on injured reserve Saturday, Brooke Pryor of ESPN.com reports.
Henderson had already been ruled out for Sunday's date with the Broncos, and he'll now be required to miss at least the next four games. He'll be eligible to return in Week 15 against Philadelphia. The No. 9 overall pick of the 2020 NFL Draft by the Jaguars, Henderson has yet to appear in a game this season.