Cracked sternum.

Just hearing the words is enough to make a lot of grown men cringe.

Ray Polk, who actually cracked his sternum in practice just before the Ohio State game, played through the breathtaking pain for the bulk of Colorado's 2011 season.

The Buffs' ferocious free safety was also making tackles and breaking up passes with torn ligaments in his wrist.

Only the contemporary approach to head injuries -- they are suddenly being taken seriously from the NFL to high school football -- kept Polk out of the lineup (he missed the Oregon and USC games due to concussion symptoms).

"It was a rough year," Polk said after a recent practice. "Being crunched up like that, it was just taking things a day at a time and pushing through it."

Colorado Washington State NCAA Football338.JPG Ray Polk of CU makes a diving interception against WSU early in the game.For more photos of the CU game, go
Colorado Washington State NCAA Football338.JPG Ray Polk of CU makes a diving interception against WSU early in the game. For more photos of the CU game, go to www.dailycamera.com. Cliff Grassmick / October 1, 2011 ( Cliff Grassmick )

Polk stands out during CU's ongoing spring drills when he's wearing a bright neon-orange penny over his uniform, which signals that he isn't allowed to participate in some of the contact drills. The coaching staff held him out of Thursday's scrimmage to make sure his surgically-repaired wrist and sternum continue the healing process uninterrupted.

"You know when Polk is not in there," CU head coach Jon Embree said after Connor Wood and the offense moved the ball well during the 41-play scrum.

In the fall, the fifth-year senior will have everyone's attention on the defense as a leader of young Buffs.

"All of a sudden I'm looking around and I'm the oldest one in the (defensive backs) room. It's weird," Polk said. "There's only a few people left from my class. It's just odd being that old dude hanging around. But it's exciting and it's a chance to help the team out by being a leader."

Polk arrived on campus in 2008 as a four-star running back recruit. With Darrell Scott, the No. 1 prospect in the country at the position, and a determined Rodney Stewart in the same class, he decided to switch to the defensive side of the ball.

Last season Polk finished tied for second on the team with 80 tackles. Strong safety Anthony Perkins also had 80 tackles, despite playing in only nine games due to his own injury problems.

The fierce competitors watched helplessly as Matt Barkley threw a USC-record six touchdown passes against the Buffs' injury-ravaged secondary during a humbling 42-17 loss on Nov. 4 at Folsom Field.

Thanks in large part to late-season contributions from Polk and Perkins, who are very close friends, CU was able to beat Arizona in the final home game and end a 24-game losing skid outside the state lines with a 17-14 win at Utah.

"What doesn't kill you makes you stronger," Polk said. "When we lost Perk it was bad. It's one of those things that when you play with somebody long enough like Perk, you get that bad feeling in your gut knowing the type of player he is. He's a great player and we needed him out there. That definitely showed in Utah."

Perkins is out of eligibility, but his presence on the field lives on in Polk, who will be mentoring a talented group of young secondary players this year.

Two sophomores (Greg Henderson and Harrison Hunter) and a redshirt freshmen (Brandon Brisco) are competing at left conerback this spring.

The battle at right cornerback is between a sophomore (Josh Moten) and two redshirt freshmen (Sherrard Harrington and River Thompson).

Parker Orms, a junior vying to fill Perkins' large shoes, is out for the rest of spring with yet another injury to the group. Junior Paul Vigo will be getting most of the reps at strong safety.

And this summer, highly touted freshmen Kenneth Crawley and Yuri Wright will join the fray.

"The influence (Polk) has on our young players, you couldn't ask for anything more," CU defensive coordinator Greg Brown said. "It's going to be hard when he graduates. I've gotten so used to depending on Ray for a long time, and he brings so much to the table."

Polk plays the game on the edge.

Last season the 6-foot-1, 205-pound black and gold flash was flagged for several costly 15-yard penalties.

With better health and some more help surrounding him on defense, Polk should be in position to make a lot of big plays for the Buffs in 2012.

"It seems like Ray's been here forever. He's a fun guy to be around in the meeting room and on the field," Brown said. "He's very popular with the other members of the defense and he relishes the chance to be the leader and to be the guy.

"And he's obviously got some strong physical traits. He's big, he can fly, and he brings the wood."

Notable

CU's scrimmage on Thursday was highlighted by a touchdown-saving tackle by junior inside linebacker Derrick Webb.

"D-Webb is starting to play like a man," Embree said. "He had a couple of huge hits."

The defense also came up with a turnover at the 2-yard line.

Otherwise, Embree said the offense executed well and Wood played like a starter should "with the exception of two plays."

Nick Kasa, who had struggled catching the ball this spring after moving from the defensive line to tight end, made some tough catches in traffic, according to Embree.

Running back Tony Jones continued a strong spring with two touchdowns. Wide receiver Keenan Canty also got into the end zone.

No injuries of note were reported.