hahahahahaha
to the OP: calm down and take a deep breath

. Shelf exams are specialized, subject-based NBME subject exams....I think they are composed of retired board questions and some questions written directly for the exam itself. Subjects that have their own exam include Anatomy and Embryology, Microbiology and Immunology, Neuroscience, Biochem, Phys, etc etc etc. They are NOT required by the LCME to be taken by students in order to graduate and obtain an MD degree, but many medschools will purchase the exams and require students to take them at some point throughout the year. In my school, some shelfs count as the final exam and those that don't at least account for some part of our final grade . Mainly, I think they are used as by medical schools as a gauge to see how their students perform compared to national averages and to see whether or not to change some of what is emphasized in the lecture hall.