So I decided to sculpt a asymmetrical hybrid in the contact pose just to brush up on some things. This is the model so far and the ref to go along with it. Snagged the concept art from CGHub. Have no idea why I chose this one.

To add to the muscle talk mentioned above. I think the hardest thing to learn are the plane changes and not exactly the muscle itself. Knowing where exactly that radius and ulna dip to create the "v" shaped plane between the two muscles. Once you got that down you are golden. I will admit I know nothing of animal muscular and skeletal flow. Big weakness on my end....