In Search of the Core Principles of Human Anatomy

A message from HAPS Central Regional Director, Murray Jensen.
A message from HAPS Central Regional Director, Murray Jensen.

HAPSters spend a lot of time discussing the teaching and learning of anatomy and physiology.  Check out this post from long time HAPSter and Central Regional Director, Murray Jensen.  Murray is trying to generate a bit of controversy about teaching anatomy and long hot lists that we require our students to memorize.  Just how important are all those names and structures?  Look forward to a retort from graduate student Bradley Barger next week.

After 25 years of teaching entry-level anatomy and physiology, I can safely say that I’ve begun to figure a few things out – like the importance of setting high expectations on the first day of class; you have to scare the kids a bit.  All HAPSters know that one.  Another thing I’ve begun to figure out is how to teach human physiology.  This is in large part due to the work of Joel Michael and his group who identified the core principals of physiology  (http://advan.physiology.org/content/33/1/10).    Energy flow, homeostasis, and a few other concepts set the stage for pretty much every topic in physiology.   I use Michael’s core principals to design my course, write curriculum, generate exam questions, etc.  It’s a powerful tool for those of us who teach entry-level physiology. Required Structures ListI also teach basic human anatomy, and after 25 years and a couple thousand students, I can say with confidence that I really don’t know what I’m doing.  I remember vividly the first human A & P course I taught.  Skeletal system .. skull anatomy…hmmm…what structures should be on the hot list?  Ethmoid? Of course. Sphenoid? Obviously.  How about the foramen spinosum?  Should that be on the list? To facilitate the decision process I used Rule One of Teaching – you teach the way you’ve been taught.  In deciding what structures to include on my own hot list, I simply went back to the notes I used as a student, “What did Dr. Ivan Johnson make me learn?” Turns out Dr. Johnson indeed had me learn the foramen spinosum; therefore it must be important, and so it went on my very first hot list for skull anatomy.   Twenty-five years later I still have my students learn the foramen spinosum.  Why?  The best I can do is “because I had to do it!” Blindly following Rule One is not professional.  I would like to do better.  Joel Michael’s core principles greatly improved my ability to teach physiology – his work established an epistemological foundation for physiology education.  Now when a student asks “why do we have to learn about vasopressin?” I can confidently answer that it fits into the bigger picture of how the body works, and vasopressin’s role in the homeostasis of sodium, water, and blood pressure.  Much, much more satisfying than responding, “Well…I had to learn it!” or even worse “Because it will be on the exam.” In the past few years I’ve been pushing my anatomy colleagues for answers.  What should kids learn about anatomy in my entry-level course? What should they learn first?  If a student wants a career in anatomy, what are the themes? What’s at the foundation of a conceptual understanding of human anatomy?  We’ve had some good beginning ideas: orientation, cavities, medical terminology, liquids and solids, layers have promise.  But there is nothing official at this stage – just some good conversations.  And nothing that helps me figure out if I should include the foramen spinosum on the hot list. Identifying the core principles of anatomy is a worthy quest, and HAPS leadership is looking into starting a task force to get things moving.  I’ve been working with Bradley Barger, PhD candidate in Anatomy and Cell Biology at Indiana University, and we’ll be hosting a workshop at San Antonio for others interested in the project. In pondering the task ahead, I think I’ve identified a significant question, but some background is needed first.  Dr. Ernest Rutherford, Nobel Prize winning physicist from way back, has a quote, “All science is either physics or stamp collecting.” I think Rutherford is correct – everything in science boils down to physics.  When teaching human physiology and thinking about Michael’s core principals, I see physics (e.g., diffusion, pumps, gradients, barriers, energy).  If students can comprehend some basic physics, then they can make some good strides toward understanding human physiology. My big question: Is there any physics in anatomy?   At this time I don’t see any physics.  I see terminology, orientation, embryology, and sometimes even design (gasp!) – but I don’t see physics. Disagree?  Disagree strongly? Well…make a list of your own core principles of human anatomy and come to the workshop in San Antonio.  Help me figure out if I should keep the foramen spinosum on my hot list.

3 thoughts on “In Search of the Core Principles of Human Anatomy

  1. Murray:
    You are correct. Most of the teaching in A&P (at least since the early 90s) has been mostly P and not so much A. However, as a guy who comes from a functional morphology background, let me say a few things that are essential.

    1. The relationship between form and function: things gotta work at least “well enough” to get things done. The physics has to be passable, not perfect. So, no catalog of, say, skeletal features (such as various foramina) is complete without an understanding of the job that the foramen has to do. To test this, we have a case study in class that compares the effects of a fulminating fungal sinus infection on the function of the eye on the affected side. The difference in the forms of the optic canal and the orbital fissures is relevant to the change in function due to the distortion of the sinus cavities.

    2. Variation: in focusing on ideal cases, we tend to overlook that there is a tremendous variation among individuals in size, shape, and proportion. Most of these are irrelevant to normal living, but a few make the individual either VERY adept at certain activities and/or very inept at others. For the most part, these have little practical impact on form and function over the normal range of performance, BUT they make interesting examples that can be used to test student understanding, rather than just memorization. It is important, therefore, that our teaching labs, especially, contain materials that are not just multiple casts of the same individual, but are actually different in a few ways—sex, age, geographic origin are the easiest to get from supply companies. Indeed, students are fascinated with the variation in the skeleton due to sex and it gives us a chance to related this variation in form to biomechanical (functional) differences.

    3. Development: The adult form of the body is, like most other things we teach, an idealized version. It is important for students to know how the body gets to be the way we expect it to be. For anatomic structures, this means understanding which embryonic germ layers give rise to them, how they are formed, and how they change over the life span. It is also important for students to know that development is *contingent*—what happened in step 1 will affect how the changes in step 2 play out. Students need to know that there is not a strict “blueprint” to follow, but a general outline. Examples of this are things like the comparison on the pattern of veins on the dorsa of the hands; or the fuzziness in the mapping of spinal nerves to dermatomes, or the development of the plexuses, and so on.

    4. Evolution: Like the development thread, our anatomy does not start from scratch. We are built on a (some say jerry-rigged) ape chassis. Certain features are quite unique to the apes—the ability to extend the elbow completely so that the hook on the end of the olecranon process “locks” into place in the olecranon fossa; this is a very useful feature for suspensory behaviors (hanging by the arms), but it also is good for resisting tensile forces in the extended elbow (as in throwing). Of course, the apes lack a tail among the primates, and there are other such features. And we can climb down the phylogenetic tree finding features in us that are found only in other primates; and then those found only in other mammals, and then vertebrates, and so on.
    4.a. On the other hand, there are things that are unique to the human lineage: sellar joint in thumb, locking knees for support in upright walking, sigmoid curves in spine, the longitundal arch in the feet, and the reorganization of the shoulders and rib cage (see the video “Why Chimpanzees Don’t Play Baseball”!!!
    Students need to appreciate BOTH of these aspects: the shared anatomy AND the unique modifications of that anatomy.

    So, there’s a start.

    And, can we do this in a guided inquiry approach? Absolutely. I think I sent Murray the example of how we approach mechanical advantage in this way. I have others that are in various stages of development.

    Let’s keep talking.

  2. One more theme … though it is probably 1.a, rather than a new entry.

    1.a. Functional Integration: the things that are most interesting about human anatomy are the things that the body DOES (and perhaps the things that it doesn’t do when something is not working right or broken). To produce something as simple as standing up from a sitting position, there are interactions from several body systems. Even though we tend to view this as a simple musculoskeletal action (perhaps with some somatic motor function thrown in), there are multiple systems that contribute to the action. Even when we look at a single action (such as, say, elbow flexion), the quality of that action depends a great deal on which muscles are activated (when and in what order), the prior position of the elbow, the quality and patency of the connective tissues that form the joint, the quality of the joint surfaces, the strength of the bone, and so on. How (and whether) these things work is important to know for students to understand. Here is a simple problem: why is it easier to do a chin-up with the forearm supinated than pronated? If students understand this, then they can solve functional integration problems.

    The other issue that Murray raised is one for the centuries: what do we include in the course … how do we decide which foramina, which spinal tracts, and so on, that will be the focus of our classes?

    Let me start by making a point that should be obvious to ALL of us: We ALREADY edit the course content. There is NO WAY to “cover” everything that is in a typical A&P text in class; we HAVE to depend on the students’ abilities to learn some of this on their own (or with our guidance). So, now that we admit that we already pick and choose the content, let’s come up with a rationale for which structures and functions we pick.

    My suggestion is this: the structures that we pick for presentation in class and emphasis in assignments should be those that clearly illuminate one or more of the themes that underlie and organize the content. For example, I have a “top 20” muscles that my students have to learn cold (after all, we spend at most 3 classes on gross muscle anatomy and function). These muscles are chosen because they illustrate several of the main themes in the course. It is not that there are no other interesting muscles; but what we are doing here (ideally) is to promote a way of thinking about the muscles for our students, rather than just a list of muscles to memorize (and forget).

    In lecture, I also use pictoral icons to represent major themes and foundation. We we are talking evolution, they see Indiana Jones’s fedora; when we are talking cellular theory, they see an icon depicting a cell, form-function relationships, Leonardo’s Vitruvian Man drawing, and so on.

    What I find in MY students (who are mostly NOT bio majors and will be headed for careers that require practical application of A&P skills, such as nursing, PT, athletic training, etc) is that they relate strongly to the gross anatomic structure and function; it is what gets them in. THEN they will move to the cell and molecular stuff as a part of the ‘how and why’ things work the way they do. But, they get totally befuddled by the typical A&P text that starts out by trying to give them a mini-course in biochemistry before they can get to the stuff that they really want to learn.

  3. You know things are going well when a comment is longer than the original posting. – Thanks, Anj! Good thinking. And I’ll try to continue on that theme — thinking!

    Over the past few years I’ve been working with high school A & P teachers and have been forced to deal with the “what do you want students to know” question more than ever before. After being pushed quite hard by my teachers, I’ve come up with “I want you to teach your students to think. Think like scientists, and more specifically, think like physiologists.” That’s a good one! Quite proud of it, actually, because I know a bit of how to do it – use inquiry activities! Activities that make students describe, control, predict and explain events in human physiology.

    But my posting was not supposed to be about physiology – it was about anatomy!

    What does it mean to think like an anatomist?

    Anj is spot-on in my opinion on the prerequisites to thinking like an anatomists – evolution, variation within a population, developmental biology, and a few more. Sure wish I had the option of taking developmental biology as an undergraduate. From what I’ve learned, knowledge of developmental biology is essential to making sense of human anatomy. So – should developmental biology be a prerequisite for an entry level A & P course? Ha. Good luck with that one.

    But here is a fun thing to do with your entry level students: AFTER you are done with the nervous system unit, and after they have taken their exams, tell them ..”oh, one more thing about the nervous system – the retina is actually part of the central nervous system, and not the peripheral nervous system.” IF you have bright students who have not taken developmental biology, that should make their heads spin! Fun!

    Long ways to go. Still working on the question “what does it mean to think like an anatomist?”

    Thanks again, Anj.

    Looking forward to a good meeting in San Antonio.

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