"He went into the hospital earlier this week, his finger that he cut a couple of weeks ago and played with, got infected," Ravens coach John Harbaugh said. "He was on antibiotics for two days. They felt like he would be fine. They felt like he would play in the game. We thought we would have him back for practice Wednesday then Thursday.
"Last night, the infection kind of beat the antibiotics. He had to get surgery on that finger to get it cleaned out. It's not major. He's not in any kind of trouble or anything like that. He's doing fine, but that will preclude him from being able to play in this game. He'll be out for this game."
When asked if this is a staph infection or MRSA infection like the situation that has afflicted several Tampa Bay Buccaneers players, Harbaugh replied: "No, I don't even know what infection that is from the other, but I've never heard anything along those lines."
Bynes will be replaced in the starting lineup by rookie Arthur Brown, the Ravens' second-round draft pick from Kansas State.
"Considering the preparation we put in this week, I'm definitely confident," Brown said. "I'm ready to go."
Brown had a left pectoral strain earlier this season, but he is healthy now. He has battled to keep weight on and has fluctuated between 227 and 230 pounds.
"He's been progressing," Harbaugh said. "He's improved, he's learning, he flies around. He plays fast. He's got a great attitude. Arthur is just a tremendous young man. He's very talented. He's learning the defense more and more each week. He's a big part of what we're doing."
Veteran wide receiver Brandon Stokley (hip, groin) isn't expected to play Sunday.
"We are continuing to rest him to get that right," Harbaugh said. "I don't foresee him playing in the game unless something changes."