A few weeks ago I got that book you recommended, I went through most of the muscles and read about them then updated them accordingly, the domestic cat cross sections were really useful because they give a really good idea of the shapes of the muscles and how they fit together, and it has those muscles that the previous sections don't cover like the adductor and deeper triceps.
but there is a little thing that i'm not sure about, and that's how much of the pectoralis descendens and transversus connect to the humerus, the book says they connect most of the way down but the in the cross section it looks like they just sit on top of everything about halfway down.
the red is roughly what I have right now as opposed to the cross section
it could just be domestic cats are weird but I can't find any information about it