Abstract
Background
The prominent nasolabial fold is a distinct feature of the aging midface. As minimally invasive procedures have become mainstream, chemodenervation is a preferred method for treating dynamic facial rhytids. We therefore sought to identify relevant nasolabial fold and midfacial muscular anatomy to determine the ideal location of neuromodulation to improve the aesthetics of the midface and nasolabial fold without altering the upper lip and smile.
Methods
Twelve hemifacial cadaveric dissections were performed to identify midface muscle origin, insertion, width, vector of pull, and neighboring structures. Attention was focused on the levator labii superioris alaeque nasi (LLSAN), levator labii superioris (LLS), nasalis, and orbicularis oculi. Measurements were obtained based on surface landmarks including the medial canthus for future neurotoxin injection.
Results
The LLSAN inserts into the medial nasolabial fold and alar base, while the LLS inserts into the middle third of the nasolabial fold. The broadest portion of the superior LLSAN was on average 8.4 mm inferior and 4.6 mm medial to the medial canthus. A separate muscle obliquely oriented between the orbicularis oculi and LLSAN was identified and found to insert into the malar fat pad. This "malar levator" was present in all specimens and has implications on medial periorbital rhytids and the tear trough deformity.
Conclusion
This study further defines midfacial and nasolabial fold muscular anatomy and provides new insights into the use of neuromodulators for these areas without affecting upper lip position. The malar levator muscle appears to be a separate midfacial muscle with independent action.
Level of Evidence V
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