It's not often that sports medicine history is made during press conferences, but Lions coach Jim Schwartz' post-practice comments Friday may prove to be an exception. Schwartz added to the catalog of player injury descriptions when he told reporters that WR Titus Young, DT Corey Williams, T Jonathan Scott and WR Ryan Broyles were held out of drills with what he termed as “camp knees.”

“[Camp knees are] just guys that get sore from a lot of reps,” Schwartz said. “No real injuries ... but we don’t want to push through knee soreness. We don’t want to push through hamstring soreness and those guys fell into that category. As soon as they’re not sore we’ll get them back out there.”

Palmer takes first-team reps: With Stephen Tulloch held out of drills with knee tendonitis, Ashlee Palmer took control of the first-team defense at MLB. Palmer's quietly solid effort during camp has justified the praise he's received from DC Gunther Cunningham and coach Jim Schwartz. He isn't the flashiest player, but he's become one of the hardest workers in a deep LB unit. Palmer has also become an anchor of Detroit's kick coverage teams. His multidimensional skill gives Detroit greater roster flexibility to retain specialists at other positions. Unlike the waiting game Palmer has played in previous seasons as roster cuts approached, he should be a lock to make the team this season.

Bentley continues to impress: If teams gave out defensive MVP awards for the opening week of training camp, rookie CB Dwight “Bill” Bentley's play has made a very strong case for the honor. Bentley took first-team CB reps at both outside and slot DB positions for the second-consecutive day, and he has made at least one head-turning play in each camp workout so far. Bentley seems to be establishing a claim to start Detroit's preseason opener. GM Martin Mayhew has been criticized in past seasons for the performance of his mid-round picks. If Bentley and fifth-round pick LB Tahir Whitehead continue their hot starts to camp, they could make 2012 one of the most successful mid-round drafts of Mayhew's tenure.

Brown and Lewis fighting for DL spots: Free-agent signee Everette Brown, and fourth-round pick Ronnell Lewis have taken reps on the Lions' second-team DL during the opening week of camp. The duo appear to be engaged in a battle for the final DE spot. Brown appears to be the more technically solid player early in camp, but Lewis' extensive special teams experience could give him an edge as workouts progress. The duo's performance represents a small silver lining to franchise tag recipient Cliff Avril's holdout. With Avril absent, DEs Willie Young and Lawrence Jackson have rotated on the first-team, giving DL coach Kris Kocurek the chance to evaluate Lewis and Brown against better competition.

Follow John Kreger's Lions updates on Twitter: @cbssportsNFLDET and @JohnKreger.