VARIABILITY OF THE MIDFACIAL MUSCLES - ANALYSIS OF 50 HEMIFACIAL CADAVER DISSECTIONS

The region of the midface represents a challenging area to both recons tructive and aesthetic surgeons.;An anatomic study was performed that attempted to identify patterns and variations of the muscular anatomy. The goals of this study were twofold: to identify patterns and variab ility of the midfacial muscles that might impact on reconstructive eff orts and to attempt to correlate this anatomy with features of the ove rlying soft tissues, specifically the nasolabial crease. Fifty hemifac ial cadaver dissections were performed. The information collected was assembled into a large data base, and statistical significance was ana lyzed using Fisher's exact probability test. Results demonstrated that , although a great degree of variability exists with respect to the mi dfacial muscles, seven distinct patterns of these muscles did emerge. The most common pattern was the presence of a levator alae nasi, levat or labii superioris, and zygomaticus major, which occurred in 44 perce nt of specimens. Specimens that possessed a risorius, zygomaticus mino r, or both, were relatively uncommon. The consistent presence of the l evators suggests adding a superior vector to recreate a smile in facia l reanimation surgery. Two important anatomic variations were noted. A bifid zygomaticus major was found to be present in 34 percent of indi viduals. Because the inferior bundle had a dermocutaneous insertion, t his anomaly may represent the anatomic correlate of a cheek ''dimple.' ' A second anomaly noted was the lateral check crease, which appeared to be associated with a cutaneous attachment from the underlying platy sma muscle. However, no correlation could be found for facial muscle p attern and the overlying nasolabial crease structure. This lack of cor relation may indicate that the facial muscles alone do not dictate th; structure of the nasolabial crease and that other dynamic factors are involved in deter mining this feature of the aging face.