Gah, stop replying and responding so promptly, I gotta go sleep /joke
Ah, I haven't the foggiest idea what's going on in that ref. I'm no cat anatomist but marked in green above are the delts, and I'm not sure where your largest, bulbous muscle directly above the tricep is coming from. The muscles of the neck seem to take on a much larger roll, and by extension size, than in us bipeds.
Now's a good time to darken up that mid-range too