Inside linebacker Zach Brown (53) was added to Washington’s injury report on Thursday. (Photo by Steve Dykes/Getty Images)

The Washington Redskins added a new name to their injury report Thursday, with inside linebacker Zach Brown sitting out practice with an ankle injury. In addition, tight end Niles Paul, who remains in the NFL’s concussion protocol after sustaining a savage hit by Cowboys linebacker Sean Lee that knocked him unconscious, was not present at practice.

Paul had been a limited participant in practice Wednesday. Asked Thursday if Paul had experienced a setback, Coach Jay Gruden said simply that the tight end was undergoing tests as part of the NFL-mandated concussion protocol.

Regarding Brown, who leads the NFL with 86 tackles, Gruden said the ankle injury surfaced Thursday. The coach offered no forecast for Brown’s availability in Sunday’s game against the 6-2 Minnesota Vikings.

“This is the first I heard of it, but we will get him some treatment today, and hopefully he will be better tomorrow,” Gruden said.

Following a two-hour practice in the team’s indoor bubble because the fields at Redskins Park were soaked and slick, Gruden essentially ruled out defensive lineman Matt Ioannidis for Sunday. Ioannidis is recovering from surgery on a broken hand and, at some point, will likely play with a protective cast that allows his fingers to move. But Gruden indicated that the bones haven’t sufficiently healed to risk that on Sunday.

Along with Ioannidis, Brown and Paul, also sitting out were left tackle Trent Williams (knee), who continued to do individual work with a trainer, and defensive lineman Arthur Jones (shoulder).

The rest of the Redskins’ banged-up offensive line participated in limited fashion, same as Wednesday. Left guard Shawn Lauvao (stinger), center Spencer Long (knee), right guard Brandon Scherff (knee) and right tackle Morgan Moses (ankles) were all listed as limited. Also limited: swing tackle Ty Nsekhe (core muscle); wide receivers Jamison Crowder (hamstring) and Brian Quick (concussion); tight end Jordan Reed (hamstring) and safety Montae Nicholson (shoulder).

Tight end Vernon Davis practiced with no restrictions, as did cornerbacks Bashaud Breeland and Fabian Moreau.

Few issues are more pressing for the Redskins, roughly 72 hours before they host the Minnesota Vikings, than the health of their offensive line.

The Vikings’ defense ranks third in total points and rushing yards allowed. It also has recorded 24 sacks through eight games.

With the offensive line ravaged by injury of late, quarterback Kirk Cousins has been sacked 16 times in the last three games, taking an especially brutal beating at the hands of Seattle’s pass rushers in Sunday’s 17-14 upset at CenturyLink Field.