Now, look at the differences with a flexed arm, and how the muscles protrude and become pronounced. this is important, because dragons, like most four legged predators, have very muscular extremities in which require much strength to use (arms, legs, wings, neck). For example, an Orangutan's arms are so powerful to aid in it's ability to skillfully hop through the biggest and tallest trees. Otherwise, where will they get the strength to climb through all those massive trees? Same rule applies here. Think of your dragons in the same exact way, and maybe even implement features into your dragons using logical reasoning of why they're there.