Morphologic asymmetries of the face: a review.

It has been suggested that asymmetries in the morphological properties of the face contribute to or produce asymmetries in facial emotional expression. Over 50 years of research on hard tissue, soft tissue, and facial surface asymmetries is reviewed here. Generally, it appears that if consistent asymmetry characterizes facial morphology, it is extremely small in magnitude or characterizes regions yet to be examined. In contrast, marked homology and asymmetry in regional size and area has been noted often. At present, it does not appear that asymmetry in facial morphology is associated with facial expressive asymmetry, with the latter more likely to be an outcome of functional brain asymmetry.