An anatomic study of the bifid zygomaticus major muscle.

The dramatic changes in facial expression are most remarkable in the perioral region. Among the perioral musculatures, the zygomaticus major (ZMj) muscle plays an important role in the facial expression. The aim of this study was to determine the anatomic patterns of the bifid ZMj through a topographic examination at the perioral region. Through 70 dissections of the hemifaces, the insertion area of the ZMj was observed in 70 embalmed cadavers. The bifid ZMj was observed in 28 cases (40%). In most cases of the bifid ZMj, the superior muscle fibers were larger and wider than the inferior fibers. Bilateral bifid ZMj was found in 71.4% of the bifid ZMj specimens. The arrangement and insertion patterns of the ZMj in this study are expected to provide critical information for the surgical planning and procedure for facial reanimation surgery.