Check this out:

http://journal.crossfit.com/2009/05/shoulder-impingement.tpl

If you haven’t bought a Journal Subscription, it’s $25/year and is one heck of a resource for an athlete. Worth every penny! In this video Kelly Starrett goes over the anatomy of the shoulder and how it works, addressing particulars for us CrossFitters and our overhead quests for dominance.

Carry on.