These are some very tricky arm poses. Proko’s Skelly app could be a good resource for you to use. I think it’s $7 in the App Store. A good price for how useful it can be. I took a few screen shots of Skelly to give you something to reference. It looks like you understand the arms pretty well. The scapula seem a bit awkward to me, but that’s all. And you were correct in identifying the Teres Major. This guy has big shoulder muscles. You dont normally see them quite that much. Hope this helps.