I read that myasthenia gravis causes, by a hypofunction of the striated musculature, a variable motor dyscoordination. also, i read that incoordination caused by hypofunction often is the cause for tmj so does that mean tmj may be caused by mg?

No: I think you posted this question before, and it was answered. No disrespect, but some of what you have read you haven’t understood, and other parts you’ve misinterpreted. That’s no reflection on you: As physicians, knowing these things and how they fit (or don’t fit) together is what we do. As far as I know, myasthenia gravis and TMJ are unrelated.