I've gotten a few 100s every now and then (not in Anatomy), but they're more about luck than anything else. Sometimes I've put in more time, and had more knowledge, for exams I scored in the low 80s than I did for exams I scored 100 on.
Even if you put all your time and effort into mastering 100% of the material for Anatomy (for me this would mean failing other classes to do so), there still exists the possibility that your professor will test you on something that wasn't covered in the material. Which, for us, has been happening with annoying frequency lately.