Greg Jennings unable to stay healthy: NFL Week 4 injury updates

Greg Jennings has yet to be healthy enough to make a significant mark this season. (Mike Roemer/AP) The players landing on injury reports need look no further

Greg Jennings has yet to be healthy enough to make a significant mark this season. (Mike Roemer/AP)

The players landing on injury reports need look no further than Minnesota RB Adrian Peterson for a little motivation.

Peterson, you may remember, blew out his knee late in 2011, yet somehow found his way back onto the field for the start of 2012. Sunday, Peterson carried the ball 21 times for 102 yards in a Vikings win over the Lions.

This Sunday brought another rash of mishaps for talented players around the league. SI.com injury expert Will Carroll helps break down the key Week 4 injuries …

• Greg Jennings, WR, Packers (groin): Jennings has been dealing with a nagging groin injury and did not return to Sunday's game with the Saints after halftime.

SI.com injury expert Will Carroll: Jennings just can't keep his groin healthy. This recurrence is showing that the Packers medical staff just isn't able to get in front of things on a week-to-week basis. He's likely to need to miss some time and, given the depth the Packers have at WR, they could do it. Missing a week should clear this up as long as this is a re-strain. Often, instead of just going back to square one, things go further, scar builds on scar, and the issue is complicated with every setback. Jennings is too important to risk that happening at this point in the season.

Who takes his spot?:James Jones had a pair of touchdown grabs Sunday, and everyone essentially would bump up a spot in the WR rotation.

• Cliff Avril, DE, Lions (back): At first glance, it appeared that Detroit's franchise-tagged defender had injured his knee -- Avril was tracking Minnesota QB Christian Ponder when he fell without any contact. The Lions later revealed he actually had tweaked his back.

SI.com injury expert Will Carroll: Avril left with a lower back strain. Those have a broad range, but there's a lot of stress on the back of a DE due to the positional demands. Just go through some of the motions there in your office or home that a DE would and feel how your back responds to those. Add in that Avril is doing it with big men blocking him, creating an extension or even hyperextension; that he takes hits that compress the spine, and absorbs more forces than you can imagine on ordinary plays. It's a wonder everyone doesn't have this kind of issue. Avril's time lost will be determined by his response to treatment and likely his pain tolerance.

Who takes his spot?: Detroit has some options at DE, including Willie Young, who's performed well when given the chance.

• Nnamdi Asomugha, CB, Eagles (eye): Asomugha was poked in the eye while covering on a pass play. He immediately grabbed for his right eye after it happened, then left the game for an extended period.

SI.com injury expert Will Carroll: Ever hear that phrase "better than a poke in the eye?" Most things are, as Asomugha found out on Sunday night. The worry, once you get past the initial pain and shock, is swelling, damage to structures like the cornea and vision changes. Asomugha was able to return, which tells us the traumatic stuff is past and that the longer-term looked good in tests. He should be fine and will likely be having the equipment manager check on those visors.

Who takes his spot?:Brandon Hughes filled Asomugha's spot during his absence Sunday, with Brandon Boykin seeing more time as well.

• Laurent Robinson, WR, Jaguars (head): Robinson was on the injury report all week after suffering a concussion. He caught one pass Sunday but a defender landed on his head during the tackle, and Robinson immediately left the game.

SI.com injury expert Will Carroll: Another one? The hit to Robinson's head looked eerily similar to last week's concussion. Robinson was cleared to play, which assumes that his brain had healed, but having two this close together is a major issue. Concussions in close succession can be cumulative, so the Jags are going to have to be very careful with this one. Robinson's progress will be monitored closely and he will not return until cleared under the NFL's concussion protocol. (Again.)

Who takes his spot?: The Jaguars' options include Cecil Shorts and Mike Thomas, with the former being the more intriguing possibility.

• Jake Locker, QB, Titans (shoulder): Locker took a huge shot from Houston's Glover Quin and the Titans announced that he had reinjured his left shoulder. His arm was in a sling as he stood on the sideline in the second half.

SI.com injury expert Will Carroll: Locker appears to have an ongoing issue with his left shoulder. He first injured it while making a tackle a couple weeks back and now a hit that didn't appear out of the ordinary caused another separation. The issue is the pain and associated changes to his mechanics, even if it is the off hand. If this continues to be an issue, Locker may need to wear some sort of bracing and consider surgery. Normally, this could be maintained and Locker could have something done in the offseason. Because QBs get hit so much, it's tough to truly protect it.

Who takes his spot?:Matt Hasselbeck reclaimed his QB spot in Locker's absence, and he will be the guy going forward.

• Brandon Meriweather, S, Redskins (knee): Meriweather appeared to injure his knee during a bizarre pregame collision with teammate Aldrick Robinson. Meriweather's leg his Robinson in the helmet, an accidental hit that also knocked Robinson from the game.

SI.com injury expert Will Carroll: Since he was already a GTD for Sunday, it's unclear whether this collision caused more issues, whether it just highlighted that he wasn't ready to play, or whether it created an unrelated issue. Meriweather will have a week to heal up, again, but knowing more about what happened should help us decide whether he'll be able to go this time next week.

Who takes his spot?:Reed Doughty started for Meriweather, so it's safe to assume that will be the play in the future.

• J.D. Walton, C, Broncos (ankle): How tough is Walton? He walked off the field Sunday only to learn later that he had broken his ankle. Oakland's Jack Crawford rolled up on Walton's leg while he was blocking.

SI.com injury expert Will Carroll: Peyton Manning isn't happy about this. The ankle is made up of many structures, so the term "broken ankle" doesn't actually tell us much. If it's merely a fractured fibula, Walton could be back in six to eight weeks, just in time for a playoff push. If there's more or if there's associated soft tissue damage, the "done for season" timeline makes more sense. This is the kind of traumatic injury that can change a team's fortune and is a bigger challenge for the Broncos than most due to Manning's reliance on his center.

Who takes his spot?: Former Patriot Dan Koppen will inherit Walton's spot. Things could be worse for Denver -- Koppen is a proven veteran with loads of experience.

• Santonio Holmes, WR, Jets (foot): In one of the more bizarre plays you'll see, Holmes caught a pass, then crumpled to the turf in pain and tossed the ball -- before he was touched down -- into the arms of San Francisco's Carlos Rogers, who returned it for a defensive touchdown. Holmes was in a walking boot after the game.

SI.com injury expert Will Carroll: I've never seen a player react the way Santonio Holmes did to his injury. Let's assume he reacted due to pain and leave that part there. Tests showed no fracture, but again, ankle injuries can involve many different structures. If Holmes has a severe sprain or strain, it could elicit the same reaction and could keep him out as long or longer than a simple fracture. Holmes is headed for more scans early this week that will help the Jets figure out exactly what's going on and how long he'll be out.

Who takes his spot?:

Jeremy Kerley

Chaz Schilens