Washington has started 11 games and is the team's second-leading scorer, averaging 10.7 points per game.
Muhammad has started every game but one and is averaging 6.5 points.
The team did not release any more details or say if the players will miss any more games.
Ohio State (11-5, 1-4 Big Ten) has lost four in a row after starting the season 11-1. The Buckeyes were ranked as high as No. 2 in the AP Top 25 but have dropped to No. 21.