It's pretty obvious that Adam Jones hurt his right arm when he fell down in the batters box in the top of the fourth inning. He has been opening and closing his right hand in center field and rubbing his elbow and bicep.
The replay didn't show where he might have hurt himself. He didn't twist his arm when he landed on both hands in the box, but he must have jammed his elbow or shoulder. Judging from the way he's reacting in the outfield, it appears to be some kind of numbness or nerve pain.
Can't be too bad, because he made a catch and didn't have any trouble throwing the ball back to the infield, but I'm surmising a lot by watching his movements on the TV feed. Let's see if he plays the rest of the game.
One thing is certain. With Brian Roberts, Mike Gonzalez, Felix Pie and Miguel Tejada hurt, the Orioles can't afford to lose another key player for any length of time.