Trying to add muscle to a 3d skeleton model I have a 3d model of a atlasaurus that I imported to blender as a .obj file and it comes up, but I do not know how to add muscle to the existing static skeleton.

I have searched online and all of the tutorials seem to be for adding muscles on the interior and thus rigging, but I want to add muscles on the exterior. I have the Blender X muscle system add-on, but I do not know how to get the muscle to connect to the skeleton bone. 

I hope this is clear, but mainly I am asking how to add muscle on top of the skeleton.
Do I have to add "bones" on top of the skeleton in order for it to work?

This is for a comparative anatomy class where we have to make some sort of 3d reconstruction of an animal. I have included an image of the object in blender that I am talking about and that I want to add muscle on top of the skeleton. 

Any help would be much appreciated!
Looks like your model is having some issues with normals and so on. This is because .Obj models are not always being imported correctly. X-Muscle System is designed to work with armatures mostly. It is possible to connect muscles directly to geometry however you will lose many advantages and automation when using this method. All you have to do is to parent muscle's both tendons to according bone. Keep in mind all dinosaur's geometry bones have to be in hierarchy, parented to each other. I hope this helps!