The Vikings signed safeties Shaun Prater and Anthony Harris to the 53-man roster Tuesday and placed safety Antone Exum Jr. on injured reserve.

The moves come less than 24 hours after all four safeties — Harrison Smith (knee/hamstring), Andrew Sendejo (knee), Robert Blanton (knee) and Exum (ribs/shoulder) — missed practice Monday.

Exum fractured a rib and injured the AC joint in a shoulder during Sunday's 38-7 loss to Seattle and will miss the rest of the season. Sendejo returned to practice Tuesday, but Smith and Blanton still were sidelined a day before leaving for Arizona for Thursday night's game against the Cardinals.

Prater was one of the final roster cuts after spending time with the Vikings in 2013 and 2014. He signed with Indianapolis but was waived in late October after playing in only one game. He has experience playing both cornerback and safety and on special teams.

Harris was promoted from the practice squad after joining the Vikings this spring as a rookie free agent out of Virginia. He also was one of the final roster cuts this summer but earned a spot on the practice squad.

"It's an opportunity to get on the field and go out there and do what I've been practicing and get better each week," Harris said. "I've been trying to focus up until this point, learn as much as I can just to be prepared for any situation that comes up."

Prater

Harris could be called upon to play a regular role with Smith and Blanton still sidelined. Nose tackle Linval Joseph (foot), linebackers Anthony Barr (groin/hand) and Brandon Watts (ribs) also missed practice for the second consecutive day.

To make roster room, the Vikings waived defensive end Justin Trattou.

Stepping in

Reserve linebacker Jason Trusnik could be in line for another busy game Thursday. The recently signed veteran replaced Barr in the base defense Sunday and played 30 snaps, 10 times more than he played in his first three games with the Vikings.

"If Anthony doesn't play, it will probably be between me and [Edmond] Robinson," Trusnik said. "We're going to have to play special teams and defense and fill in where they need us and step in so the defense can keep rolling."

Trusnik had four tackles last Sunday, one for a loss. Barr has been one of the Vikings' best defensive players this season with 61 tackles and 2.5 sacks.

"I don't think the approach [without Barr] changes at all," Trusnik said. "This is my ninth season now, and whether I've been starting, filling in, backing up in multiple different positions and playing special teams, I take the same approach each week … so the defense can keep up the pace and keep going."

Short week

If it was up to Mike Zimmer, he would move Thursday night games to Friday. The Vikings coach coached Thursday games each year he was with Dallas (1994-2006), so the schedule challenges aren't new, but they never get easier.

"It's a grind," Zimmer said. "But it is what it is. Everybody has to do it."

Adrian Peterson agreed: "That's one thing you look at and swallow for what it is and get it done."

No break today

Zimmer found time to get home Monday night, but not before stopping for a late meal at McDonald's. The only problem was, his order was short.

"I did go home last night for a little bit and I went to McDonald's on the way home 'cause I was hungry and I ordered two cheeseburgers and only got one," Zimmer said. "That's the kind of week it's been."

The media got a good laugh out of Zimmer's comments, but he wasn't done. When asked if he didn't play the "Do you know who I am?" card, he responded, "They probably did. That's why I got one."