UPDATED - 02NOV2015
A MUCH NEEDED overhaul of an old dragon anatomy guide as a Sponsored Commission by ImaFlippingNinja of FA.
The last version of this was done over two years ago, and when I realized it was /still/ the first submission that popped up when I searched my name, my skin crawled and I had to update it, haha. This newer version is much more refined, accurate, neater, and overall much more comprehensive.
Just showing some basic muscle groups on a standard feral western dragon, and how these can be broken into easy shapes. I hope this helps. ^^ I also threw in some additional colour-coded dragon pieces to show the 'basic shape groups' of dragons of varying anatomy. If anyone has any questions on anything specific, let me know. I am by no means an expert on animal anatomy, but I'll answer any and all questions to the best of my ability.
I will be making additional tutorials for more specific aspects such as basic dragon design, anthros/furries, updating my 'Dragon Feet' tutorial, and a wing-specific tutorial. Anything in particular you think I should cover? Throw a suggestion my way, or consider sponsoring a tutorial like this which will be fine-tuned for you!