OWINGS MILLS - Six-time Pro Bowl center Matt Birk missed his fifth consecutive practice Friday due to back spasms, an ailment expected to keep him out until after the Baltimore Ravens' first preseason game next week.
Birk underwent surgery during the offseason to address varicose veins in his legs.
Now, the 36-year-old is dealing with a back problem as the Ravens prepare for next Thursday's preseason opener against the Atlanta Falcons at the Georgia Dome.
"Matt is resting," Ravens coach John Harbaugh said. "He had some back spasms, too. It's probably both me and Matt. Matt has had the back spasms, but I'm going to probably slow him down a little bit more, especially this week. Maybe next week after the game, we will get him back a little bit more."
Birk has a history of injuries in recent seasons, including issues with his knee, neck and elbow.
The Harvard graduate is durable, though, never missing a start since initially signing with the Ravens three seasons ago. Birk underwent arthroscopic surgery on his left knee last year during training camp, but was ready in time for the opening game against the Pittsburgh Steelers despite an abbreviated preseason.
The Ravens have been pleased with the work of rookie center Gino Gradkowski, a fifth-round draft pick from Delaware slated to back up Birk.
"He's a young guy, physically," Harbaugh said. "He's very smart. He's very tough. He's very competitive, kind of a tough, mean nasty type of guy. We like his style."
SMITH SIDELINED: Cornerback Jimmy Smith missed practice due to a back injury suffered during an indoor practice Thursday afternoon.
"Jimmy's back locked up," Harbaugh said. "It's all muscular. It's something that happened to him in college. It takes a couple of days usually for that to loosen up."
Defensive end Arthur Jones was out the past two practices with a hip flexor injury. He had a magnetic resonance imaging exam, which revealed no tear and that it's only a strained muscle.
"He had a hip flexor issue that he's been fighting through for the last couple of days, so we decided to get it looked at," Harbaugh said. "Don't expect it to be serious, but we wanted to check it out and make sure."
Offensive guard Bobbie Williams (right ankle) returned after missing one day of practice.
Several other players didn't practice Friday, though. That included Pro Bowl fullback Vonta Leach, who was given a day off due to a tight back. Leach is also the only fullback on the roster.
"I held him out," Harbaugh said. "His back started to tighten up, too, so I held him out a little bit. That's part of the camp deal, especially those guys who are a little bit older."
Also not practicing: linebackers Courtney Upshaw (right shoulder), Terrell Suggs (partially torn Achilles tendon), Josh Bynes (undisclosed) and Dannell Ellerbe (undisclosed), cornerbacks Cary Williams (hip) and Asa Jackson (undisclosed), tight end Dennis Pitta (broken right hand), offensive lineman Jah Reid (strained right calf), wide receivers Tandon Doss (hamstring), David Reed (ACL surgery) and Patrick Williams (undisclosed), and running back Bernard Pierce (strained hamstring).
M&T TODAY: The Ravens have an open practice today at M&T Bank Stadium at 5 p.m. with gates opening at 3:30 p.m.
"It's a practice, yes, but it's a ramped-up environment," Harbaugh said. "Last year, some of our young guys went into that stadium atmosphere, who had been practicing well, and didn't practice so well. The environment got them. So, it's a chance for them to get into that different kind of setting.
"It's a little bit bigger than the practice field out here and perform in that kind of a setting, be able to just take the whole thing, internalize it back to your own performance, cut that crowd out of it and play football."
QUICK HITS: Former Pro Bowl kicker Billy Cundiff was given the day off. Rookie kicker Justin Tucker made 5 of 6 field goals, coming up just short on a 60-yard attempt. ... The Ravens list receiver Jacoby Jones as their top punt returner and kick returner on their official depth chart. ... Bryant McKinnie is listed as the starting left tackle and Michael Oher as the starting right tackle. ... Special Olympics of Maryland athletes attended the practice. ... Pro Bowl offensive guard Marshal Yanda delivered a message to the team. " His words were, 'Embrace the grind,'" Harbaugh said. "Perfect for training camp, right? He talked about 'physical' being the foundation of being a football player and what this football team is all about, and he talked about having fun. It's a game that we should love. It's a great game, and we all love it, so even though it's 105 degrees, or whatever it is, make the most of it and enjoy yourself."