DOUBLE OR BIFID ZYGOMATICUS MAJOR MUSCLE - ANATOMY, INCIDENCE, AND CLINICAL CORRELATION

The anatomy of the double or bifid zygomaticus major muscle is investi gated in a series of 50 hemifacial cadaver dissections. The double zyg omaticus major muscle represents an anatomical variation of this muscl e of facial expression. This bifid muscle originates as a single struc ture from the zygomatic bone. As it travels anteriorly, it then divide s at the sub-zygomatic hollow into superior and inferior muscle bundle s. The superior bundle inserts at the usual position above the corner of the mouth. The inferior bundle inserts into the modiolus below the corner of the mouth. The incidence of the double zygomaticus major mus cle was 34% in the present study, as it was found to be present in 17 of 50 cadaver dissections. This study shows that variation in the indi vidual morpholo,oy of the mimetic muscles can be a common finding. Cli nically, the double or bifid zygomaticus major muscle may explain the formation of cheek ''dimples.'' The inferior bundle was observed in se veral specimens to have a dermal attachment along its mid-portion, whi ch tethers the overlying skin. When an individual with this anatomy sm iles, traction on the skin may create a dimple due to this dermal teth ering effect. Clin. Anat. 11:310-313, 1998. (C) 1998 Wiley-Liss, Inc.