Reddit reviews Skeletal Muscle Structure, Function, and Plasticity

First on my list for everyone on this subreddit to read is Overcoming Gravity. It doesn't go into great amount of detail on insertions and functions and whatnot, but it does teach you a lot about your body.
In the same vein, I would recommend Practical Programming.
Starting Strength has a bit more emphasis on what does what in general movements. Yeah, it's a barbell training book, but it provides a lot of insight.

More on the physiology side of things, I'd say Skeletal Muscle Function, Structure, and Plasticity. It isn't perfect, but it's pretty good. It also teaches you a bunch about anatomy which is a nice bonus.

That being said, I don't think real anatomy is that important. Personally I've accumulated the things I know about anatomy over time. Only yesterday I learnt where exactly the infraspinatus and teres minor insert at the shoulder, for instance. Because what do you really need that kind of knowledge for? Determining the cause for injuries is just guesswork if you aren't trained for it.
I think it's more important to know about the general groups and what they do; for instance, the glutes do hip extension and the hamstrings do both hip extension and knee flexion. In short, it's more important to know what the muscles do rather than where exactly they insert.

> looking at muscle performance in the presence of chronic spinal cord injury.

Have you read this textbook, by any chance? It has a big chapter at the end devoted to nervous system injury models.