Concepts of variation and normality in morphology: important issues at risk of neglect in modern undergraduate medical courses.

In anatomy, normality embraces a range of morphologies and includes those that are most common and others called variations which are less frequent but not considered abnormal. Variations ranging from subtle to remarkable affect every part of the human body. They may have important influences on predisposition to illness, symptomatology, clinical examination and investigation, and patient management including operative surgery. Recognition of variations enables clinicians to distinguish features which merit further investigation or treatment from those which do not. We believe the concepts of normality and variation should be introduced early in the medical course and that the dissecting laboratory is the ideal venue. Students who are able to examine several specimens or are privileged to dissect soon realize that each cadaver is unique. Knowledge of variations should be reinforced in several components of the medical course where physical examination, imaging investigations, surgical procedures, and autopsies are studied. Appreciation of the range of normality including variations matures as experience is gained over several years. Current trends in undergraduate courses--including reduced exposure to dissection and dissected specimens, increased use of plastic bones, models and computer-generated images, loss of experienced teachers, especially those who are medically qualified, and loss of morphological approach-- all conspire to defer the stage when students encounter variation. We are concerned that these trends will compromise the knowledge and understanding of variation required to start practicing medicine safely and competently.