The 6-foot-8, 300-pounder hopes to be cleared to play for Arizona's home against Seattle on Thursday night. Another test was scheduled for Monday.
Campbell underwent tests at Stanford University' for possible neck and spine injuries, and all results were favorable. He was released late Sunday and flew to Arizona in the plane of Cardinals President Michael Bidwill.
He participated in the team's walk-through practice Monday and expressed no qualms about returning.
"I feel pretty good now," he said. "Football's my life. I'm definitely looking forward to strapping it up and playing again."
Coach Bruce Arians said Campbell bruised his spine, but Campbell said he wasn't' exactly sure what was wrong.
"It was scary for a second," he said.
Teammate Sam Acho saw Campbell on Monday and tweeted: "He's smiling and looking as good as ever."
Meanwhile, 49ers owner Jed York criticized some of his team's fans for doing the wave while Campbell was down. He said in a tweet Sunday that to say he was "disappointed would be an understatement." Arizona linebacker Daryl Washington called the fans' reaction "disrespectful."
Campbell called it "not that big of a deal" and said all he heard were cheers of support.
"When I got off the field I put my thumbs up," he said. "The crowd gave me a pretty good cheer. So I felt pretty good about that. I felt a lot of love coming off the field."
The lineman said he was injured trying to make Frank Gore fumble.
"I put my head down," Campbell said. "I got up with kind of like a stinger feeling, but it went all the way down to my feet."
Medical personnel took no chances even though feeling began to return to his hands and feet while he was still down on his back.
"I wanted to get up," Campbell said. "But they wanted to make sure nothing serious was wrong."
He was strapped down so he couldn't move as he was taken off the field. Arians said he's seen a number of players carried off on a stretcher and was encouraged by Campbell's reactions.
"He was coherent and talking and you could see the fingers and feet starting to come back pretty fast, so I was very optimistic," Arians said.
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