The Bill Hartman Podcast for The 16% - Season 11 - Number 1 Podcast
Right, it shifts it downward, doesn't it? Yes, that's why you can't raise your arm overhead when you have a superior glenoid labrum tear. It's not that the muscles aren't lifting the arm. It's never going to happen—no matter how hard you try, it's such a tiny little thing. But what it does do is push the fluid content down underneath the humerus, which lifts the arm up. But if I don't have enough muscle to do that, I can no longer shift the fluid down. So the fluid stays at the top of the shoulder joint. And guess what? I can't compress the fluid compartment because it doesn't compress—it's water—and I can't raise my arm up. So I can't overcome that.
shoulder biomechanicsglenohumeral jointfluid dynamicssuperior glenoid labrummuscle function