You should defintely try to get your hands on Dr. Fulford's book "A Touch of Life." It goes into some basic understanding of OMM. A true Osteopathic physician uses his hands in both diagnosis and treatment. The range of conditions OMM can treat are most definitely not limited to musculoskeletal injuries/problems. Unfortunately, while the art of OMM is touched upon in school, few D.O.s go on to master it. It is my hope that this will change in the future.
But for real, go pick up that book. It's an easy read. I also know that a book was written after Dr. Fulford's death. He is an interesting person and is well-known amongst old school Osteopaths and hard-core proponents of OMM. Dr. Sutherland is also worth a look as well. And of course, A.T. Still's book tops the list but it is hardcore and should remain a companion throughout the years.
Okay, enough of my blibber babber.
Peace
ATM