Functional asymmetry in the face.
The possible existence of one-sided dominance in the face, similar to the phenomena of handedness and footedness, has been investigated by studying smiling pattern, movements of the angles of mouth, winking, platysma contraction, raising and everting the upper lip with dilatation of the nostril, and vertical wrinkling of the forehead, on 300 right-handed and 30 left-handed persons. The conclusions are as follows: 1. The large majority of persons investigated do not use the two sides of face equally. 2. Facial ambilaterality is a rare feature. 3. There is no clear-cut correlation between handedness and the dominant side of the face. 4. The greater percentage (58.66%) of right-handed persons show a left-sided smile and find it more convenient to perform almost all exercises with the left side of the face. A still greater percentage (73.33%) of left-handed persons shows a right-sided smile and a better performance of all exercises with the right side of the face. The contralateral relationship of handedness to the dominant side of the face is significant in the right-handed and more so, in the left-handed persons.
D000293:Adolescent; D000328:Adult; D002648:Child; D004292:Dominance, Cerebral; D005145:Face / Q000033:anatomy & histology / Q000502:physiology; D005260:Female; D005528:Foot; D007839:Functional Laterality; D005824:Genetics, Behavioral; D006225:Hand; D006801:Humans; D008297:Male; D012904:Smiling