Studying for the Basic Sciences and (preclinical) NBME Shelf Exams

Some thoughts for intrepid and probably antsy first-years as they stumble upon this page on their search for the truth. Here are some tidbits about the Anatomy, Physiology, Biochemistry, and Microbiology shelves.


Anatomy, if learned well over the year, is doable. It is crammable if (and only if) you’ve actually paid attention and learned everything once. This is not the time to learn anything for the first time. Even with a good background, the anatomy shelf tests a ton of material. Pay special attention to high yield parts—things that are often injured or easily framed in a clinical vignette. While everything is there, it’s not there equally often.

For example, collateral circulation is a big favorite for several systems. You’ll see questions that involve arterial transections from stab wounds as well as a occluded arteries from cholesterol plaques. You need to know what other arteries can supply these areas–they’ll be there in spades. Focus not just on knowing body parts but also on 3D relationships between body parts, because they’ll often ask for one part in relation to another (the structure immediately lateral to the X is….).

Lastly, pay attention to common injuries and conditions. If someone falls on an outstretched hand, what bone is probably broken? Scaphoid. What bone is most likely dislocated? Lunate. So on and so forth.

Favorite books: Moore for the textbook (though your school syllabus may be enough). Rohen for the atlas, end stop. (I prefer real photos to Netter drawings, though the combination is synergistic; Netter shows you the ideal relationships; Rohen shows you how to actually identify structures on your practicals).

If you want a combination of Netter-style illustrations mixed with a healthier amount of explanatory text and some nice tables, consider Thieme’s Atlas of Anatomy (it’s excellent; the downside is that your school probably isn’t using it as the official text).


Memorize lab values, especially if you’re the type who doesn’t finish tests quickly (this is also a time-saver on the Step 1). More so than other shelves, Physiology clinical vignettes often include lab values that are actually key to understanding what’s wrong (not the case for Microbiology, for example, where lab values are almost always superfluous). Because the test demands more problem solving/reasoning over rote memorization, the physio test is also one of the more tiring, in my humble opinion.

Almost all physio questions require knowledge of the various trends and formulas; they usually demand that you know why something happened or what happens next. For example, you need to know the body’s compensatory mechanisms to keep fluid volume stable, and how these are used to correct for hemorrhage, dehydration, diabetes insipidus, etc etc etc. If something going up makes something else go up or down, then there will be a question about it.

Also, know your renal.

Favorite book: Costanzo, easily. She also wrote the BRS Physiology Review, which I’ve heard good things about.


Buy a set of notecards and memorize them. Know all of the incredibly rare diseases and what enzyme is deficient in the pathway. Not much to say here: it’s a hard test. The things that are most often covered in detail in your biochemistry class are the things you must know in greater detail. So, you have to know metabolism incredibly well. Intimate knowledge of pathways like glycolysis, glycogenolysis, and gluconeogenesis is very high yield. For less important topics, like microtubules, basic gist-level knowledge is sufficient.

Favorite book:  I used the course syllabi supplemented with the wordy but quite good Lange flashcards. Lippincott is the common favorite. Goljan’s Rapid Review covers the topic nicely as well and many people end up buying it anyway. I’ve also heard pretty good things about First Aid for the Basic Sciences.


The most crammable exam. First, know basic virology and bacteriology. How they work, change, evolve etc. You definitely must learn about the multiple ways bacteria become virulent and gain new genetic material. A lot of the test comes directly from the sort of stuff everyone overlooks when they start memorizing pathogens.

Second, for clinical vignettes, a good notecard set is always helpful. For most pathogens, there are a handful of key words that will set you off to the question—they usually ask for either an identification or a secondary fact about it. Everything else in the question is just time-wasting fluff. Memorize the key relationship, and you will be fine on the majority of the vignettes. Will you really understand what’s going on? Probably not, but these questions are often designed to test your knowledge of these stereotypical cases, not whether or not you’ll actually be a competent physician.

For example, H. pylori, which causes gastric ulcers produces urease. If you see a patient with an ulcer, the answer is probably either the ID or the enzyme. Aspergillus makes a “fungus ball.” Coccioides forms a spherule in the body. People who get a non-healing lesion after being pricked by a rose thorn have an infection from Sporothrix. If a bacteria is coagulase positive, it’s Staph aureus. It really is that superficial. Key word -> answer. The difficulty comes from information overload. The more rare the disease, the more likely the question will be an easy form of memory recall (e.g. fever that goes up and down (undulates) is Brucellosis). For more common bugs like Staph and Strep and the very well-known classical diseases (Malaria, TB, etc)—do a better job nailing down greater details.

Favorite book: Clinical Microbiology Made Ridiculously Simple, hands down. For rapid bug review, try the BRS flash cards. Fast and painless and better than making your own.

And that’s it. You’ll be fine.

(Keep in mind: Questions are good. Do questions. If you have cash to burn, USMLE World has plenty of them. You can also find my compilation of free study resources for the basic sciences here. You can find my views on the pathology shelf here.)

NBME Shelf Exam scores, with a grain of salt

The NBME Shelf exams are enjoyable standardized tests that every first year looks forward to with almost unbearable glee. Each tests a single subject (“Anatomy”) and is (for the preclinical years)  made up from the old or junior varsity questions from the USMLE Step 1, a test that makes the MCAT look like the GRE and the SAT look like building with Lincoln logs.

Some schools force their students to take a variety of Shelf exams (spending/wasting $30 a pop) to help measure how well their students have mastered the material (AKA how they are doing compared to their national counterparts). What is a bit amusing and misleading about the whole ordeal is that the national norms are probably a big crock.

Different schools use the “shelves” differently. Some use them as a just-for-fun intellectual exercise, others as extra-credit, and still others as a true final exam. Don’t get me wrong, it’s not a bad thing to get some USMLE Step 1 experience, but it’s highly dependent on the environment: if you take five shelf exams in a single week, you are clearly not going to be prepared or even particularly focused. If it’s your final exam, you are going to do your best to rock it.

So if the national average is computed from all of these groups together, then it’s going to have a huge unseen left tail: if people are taking the exam who don’t care how they perform, they’re going to be dragging the average down from where it would otherwise be. So while the test is technically normalized, it’s not the same normal as a regular standardized test: Unlike the MCAT, not every student has something riding on the exam. I personally knew people who filled out all C’s on an exam that was for extra-credit only.

While your school receives the group’s average and your grade relative to your test group (classmates), the theoretically more interesting numbers a student receives are the grade based on the national average and corresponding percentile. I’m curious as to how far off the scores really are. If all those people who weren’t making a good faith effort actually tried (as they do on the USMLE Steps 1, 2, 3), then I’d wager it’d be a different ball game. It’s essentially an unstandardized standardized test.

Further reading: How NBME Shelf Scores Work

Anatomy of an NBME Shelf Exam

The NBME offers comprehensive subject exams, ostensibly to torture students and devour whatever scraps of self-worth they have left. The typical question format:

A X-year-old [type of person] reports to the doctor/ER with a X-hour/day/week/month/year history of not-feeling-so-hot. Upon examination, distracting details. Irrelevant information. Single key relationship. More words to make the test take longer. Talkie-talkie. What is the likely cause of this you-should-have-learned-in-your-class-and-probably-did-but-maybe-you-didn’t-who-knows-there-are-so-many-questions-on-this-test-it’s-all-a-blur person’s problem?

Rinse and repeat for three hours. Then do it for it every class you take. The joys of biochemistry could never be fully appreciated until they were compiled in such a form.