DON'T draw your fur like this; it looks ridiculous. This is just an illustration.
Knowing the grain of the muscle, and how the fur lies down on different parts of his body may seem kind of pointless at first, but it will help for some of the more odd angles you may draw. If I draw Nicholas lying on his side, I'd be outlining different bits of him than if I were drawing him at a straight-on angle. Those different would probably have different muscle masses that would affect his fur, if only slightly.