Is There Anything Amiss with this Scapular Movement?

Hello!

New here. Am on a long quest to rehab and injury-proof my body.

I have all kinds of problems. Right now I’m focusing mostly on my scapulae. I learned recently that my middle and lower trapezius do not fire the way they should. My shoulders easily suffer as a result.

So I’ve been trying to activate them. I think I’m on the right track with the middle muscles, but I can’t for the life of me imagine what the lower ones feel like when activated.

I made a video, hoping that someone might pick up on erroneous movement somewhere.

The downward jerks near the start of the video are lats activation.

Grateful for anything you have!!

Once this is fixed I can address the other four problems/injuries…