Variation: Anatomical Constant, Clinical Imperative, Educational Dilemma
Authors: Royer Danielle F. 
Published: June 2021

The quest for the Vitruvian Man, a living embodiment of Nature's Design, was pervasive in much of the work of early anatomists and remains prevalent today. Yet observations of anatomical variation are as old as the study of anatomy itself. Thus, the notion of an ideal human form is at odds with centuries of direct observation in the dissection lab and clinic. Anatomists have long recognized that the body exhibits a flexibility of form and pattern which generally does not hinder its function. This flexibility, termed normal range variation, is an anatomical constant – the norm rather than the exception. As numerous examples highlight, an understanding of normal range variation is not arcane knowledge; it is essential to clinical practice. Clinicians encounter variations on a daily to weekly basis, and advances in imaging have made it easier to detect variations in living patients. Ignorance of variation has been shown to lead to medical errors, including misdiagnosis of exam or radiological findings, surgical complications, and unnecessary procedures. Knowledge of normal variation is critical for surgical planning and safely performing a wide range of landmark‐based or image‐guided procedures. An extensive inventory of anatomic variations has been amassed, yet this information is scattered and challenging to access in a point‐of‐care or educational context. Furthermore, reduced time for anatomy instruction combined with a decreased reliance on dissection may mean that trainees receive less exposure to the normal range of variation than in the past. Medical educators struggle with when to introduce concepts of variability, how to balance an appreciation of variability with the need to memorize hundreds of specific variants, and what resources to select for different stages of training. Despite these challenges, physicians and residency directors agree that variability should be included in undergraduate medical education. A recent survey of anatomists from MD‐granting schools reveals variation in how variation is taught. Some trends emerge: relationship variations rate highest in perceived importance while muscular variations rate lowest, students are assessed on variations at about half of schools, and over half of faculty report dissection as the primary way students are exposed to variations. Echoing the views of residency directors, most anatomy faculty agree that medical school is the best time to introduce concepts of variability. Students exposed to common and clinically‐relevant variations (e.g., brachial plexus composition and relationships) through a focused module reported a significant increase in their appreciation of the clinical significance of variation, and a significant decrease in their belief that learning about variation is boring. This work suggests that strategies which explicitly and deliberately call attention to normal variation and its clinical relevance may help students develop an appreciation for variability, which may be more valuable than the rote acquisition of facts. Educators and clinicians should help students cultivate a mindset that expects variation, rather than a static Vitruvian model, to better prepare students for specialty training and clinical practice. After all, variation is the spice of life and the norm in anatomy.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.