It's a shame that OMM, or any class for that matter, is taught in such a way that the majority at your class cannot grasp it. You might want to check out the book "OMT Review" by Savarese. It has been very helpful for my practical exams, as far as naming dysfunctions and further explaining the functional anatomy. If you can understand the basics of what you're doing and why you're doing it, that is not too bad in my opinion. I'm assuming that you are an MSI, so functional anatomy is all OMM has been so far, as we haven't started treating yet, just finding normal/abnormal somatic function.
Regarding the written exams, our first one is coming up this week, and from what I have heard, it sounds like what you have described above. There is a lot of minutia and other details from the foundations reading that most of us will not deem important. The important point to remember here is that if your entire class is having trouble with it, and the average is low, you have nothing to worry about. When rankings come out later down the road, and you have all had to struggle on the same brutal exams, scores are down for everyone, not just you.
Hopefully this was somewhat helpful. I always find it to be such a shame when I hear recent graduates who can't use OMM because they never really learned the basics and did not become proficient at it. For some people, just being able to coast and fake your way through the practicals is the path of least resistance, so they will do just that. I know that I may never be amazing at OMM, but I think as long as I come out knowing a few treatments for common problems such as back pain and headaches, and increased diagnostic ability, I will be satisfied.
