Fantasy Anatomy: Wing-ed Humans

Something that annoys me, as made apparent by my previous mermaid related rant, is fantasy anatomy that doesn't account for the actual movements necessary for the modifications or additional appendages to be useful. The addition of wings, to otherwise human characters commonly suffers from this pitfall.  For whatever reason, generations of writers have attached wings to the shoulder blades. If you were dealing with insect based wings, such as those of a dragonfly, bee, or butterfly, as commonly found in descriptions of fey folk such as pixies, it isn't so much an issue as the mechanics involved in their flight are distinctly different from those of bird or bat wings.  

For characters with bird or bat-like wings however, the range of motion needed to actually fly isn't possible if the wings sprout from the shoulder blades. These wings are attached to the animals body from the glenohumeral joint, or where our arms attach to our torsos, and need the same range of motion as our arms to perform their purpose. (Yes, I did look up the technical name for that joint.) Wings mounted in the middle of one's back would only get half the needed movement and thus would be unable to produce the amount of thrust necessary for actual flight. They'd be able to glide, if launching form a high enough place, but that would require climbing to a high enough elevation every time they intended to do so, which seems a bit counterproductive.  

There are basically two options for having functional wings on an otherwise human body. Firstly you can replace their arms with wings. The downside of this is that the size of wings necessary for flight means that the wings would be absolutely massive with elbow joints that extended well below the knees. They would be fully functional for flight, but not much else, and would probably be rather ridiculous in appearance. The second option is to have additional skeletal structure, including a second set of glenohumeral joints.  These secondary shoulders would need to be be set a bit wider, and possibly higher, then the set attached to the arms to, again, allowing for the fully range of motion necessary for flight. The down side to this is the reduced range of motion in the arms. However, as trying to scratch your back is already an activity most easily accomplished with the help of friend or family (or back scratching device), I don't feel that the loss is of much significance, especially in exchange for the ability of flight. And on that note, let's just leave the whole issue of tail feathers off the table for now. So, in short, understanding anatomy is important, even in fantasy.