Harry Potter and the buggered shoulder

So after I posted my video and showed it to the boffins at the Big Cricket forum, I got a fair few comments about where my arm was relative to my shoulder. It seems I need to take a few more trips to a physio.

It would appear that I have an impingement of a particular muscle in my shoulder, which is why I tend to have such a round-arm style, and this is possibly causing most of the problems I'm having with a sore right shoulder. The muscle in question has the most fabulous name, sounding much like something Harry Potter would exclaim shortly before letting rip with a particularly vicious Shane Warne-style leg break:

"MUSCULUS SUPRASPINATUS!!!"

So perhaps we're finally getting to the bottom of my shoulder problems. There were a few on the forum saying that until this is solved I won't be able to make progress, so it could be I need to be less hard on myself about my lack of sustained improvement recently.