There is an anatomic explanation for upper lip and midfacial tethering resulting in lack of motion in facial synkinesis.

To measure the effect of perinasal chemodenervation on dental show in the synkinetic population and clarify the anatomic relationship of perinasal musculature.

Literature search was performed on anatomy of the perinasal modiolus, and anatomic evaluation was performed through human anatomic specimen dissection.

Photographic outcomes were observed in synkinetic patients receiving chemodenervation to smile antagonists with and without perinasal muscle injections and assessed through naive observer survey.

Retrospective outcomes for all patients receiving perinasal chemodenervation was collected utilizing Facial Clinimetric Evaluation Scale, Sunnybrook Facial Grading System (FGS), Facial Disability Index (FDI), and the Synkinesis Assessment Questionnaire.