ABSTRACT
Bilateral symmetry of the musculoskeletal system is a phylogenetically widespread characteristic of many complex organisms (Palmer, 1996). There is a midline plane of symmetry that divides the body into right and left halves, so that one half is essentially a mirror image of the other. However, asymmetries in form are frequently observed both in natural populations of organisms and in clinical settings. Some of these asymmetries can be very subtle. For example, while normal human faces may appear symmetric on casual inspection, some slight differences between sides can always be found. In other cases, there may be asymmetries that are immediately obvious. Some large-scale, conspicuous asymmetries may occur in normally symmetric structures because of developmental anomalies (e.g., hemifacial microsomia), and there are also dramatic asymmetries that occur normally in natural populations (e.g., the skulls of flounders).
