Palmer sat out a 20-12 loss to the Cleveland Browns on Sunday because of inflammation in his passing elbow, an injury that the team didn't reveal until late in the week. When he'll be able to play is hard to say.
"It's not bad," said Palmer, who was listed as the emergency quarterback and watched from the sideline wearing a cap. "I'll probably be able to prepare this week."
Palmer had an MRI that shows no structural damage but the pain, inflammation and swelling persisted since his arm got pinned during contact in last week's game, ESPN's Chris Mortensen reported.
It's a major setback but not a surprise for the Bengals, who are 0-4 for the first time in six years. They've had a hard time protecting Palmer all year.
Palmer broke his nose in the preseason, then sprained his left ankle in the second game of the season. He got his nose bloodied again in an overtime loss to the Giants last Sunday, and hurt his elbow when he was hit while making a throw. He finished the game, but the elbow became more tender as he threw during practice last the week.
"It happens a lot," Palmer said. "Sometimes it takes a little while to come back. Hopefully it won't take too long."
Coach Marvin Lewis told Palmer on Saturday night that he was going to sit out.
"He's got an elbow that's inflamed," Lewis said. "It's better. It was precautionary to not let him play -- against his wishes -- and have him ready for next week and beyond."
Ryan Fitzpatrick ran the offense in practice Friday, when the Bengals revealed Palmer's injury. He was surprised when Palmer told him on Saturday night that he wouldn't play.
"He's an iron man," Fitzpatrick said. "A lot of times, he'll get dinged up in a game and you won't even notice. He never misses a practice."
The Bengals got Fitzpatrick in a trade with the Rams before last season. He hadn't thrown a pass in a regular-season game since 2005, when he started three games for St. Louis. He looked rusty as Palmer's replacement, throwing three interceptions while going 21-of-35 for 156 yards and a late touchdown.
"As the backup, I see myself as the game manager," Fitzpatrick said. "You have to take care of the ball and not lose the game for the team."
Fitzpatrick finished as the Bengals' leading rusher, picking up 41 yards on four scrambles. Cincinnati managed only 211 yards -- the third time this season they've had 215 or fewer.
The offense looked better in the loss to the Giants, who won in overtime 26-23. It was back to square one -- or worse -- with Palmer out.
Palmer missed the last three games of the 2004 season -- his first as the starter -- with a sprained knee. He tore ligaments in his left knee in the Bengals' first-round playoff loss to Pittsburgh in 2005, but didn't miss a game the next season, underscoring his determination to play through injury. He took every snap last season.
The Browns expected Palmer to play.
"That's their staple," said offensive lineman Eric Steinbach, who also played in Cincinnati. "He's their leader. So I think their confidence might have been shot a little bit."
Bengals cornerback Johnathan Joseph also was inactive for the second consecutive game with a sprained ankle.
Information from ESPN Senior NFL Analyst Chris Mortensen and The Associated Press was used in this report.