Now that's interesting. I am currently having physio for what I have been told is 'impingement' in my shoulders, which results in referred pain in the upper arms, between the shoulders and the elbows. If I try to stretch my arms to reach for anything, such as in the car glove box, behind the seat, or reaching up into a cupboard, I get an aching pain like a toothache but in the arms, which lasts for about 30 secs and hurts like hell. I also have restricted rotational movement because of the pain it causes. It is supposedly caused by inflammation of the ligaments/tendons that run through the rotational cups in the shoulders. This can be caused by wear, age and sitting too long at a desk using a computer, or so I was told by the physio.