Abstract
The platysma muscle's role in lower face dynamics is complex. Multiple insertion points to soft-tissue structures at various levels in the lower face create make for a multi-faceted contraction pattern. To avoid adverse effects in cosmetic procedures when targeting the platysma, its anatomy and physiology must be understood. Clinical observations hint to a bi-directional contraction pattern.
Eighteen healthy volunteers (13 women and 5 men) with a mean age of 44.2 ± 10.1 years were enrolled. Skin displacement vector analysis was used upon maximal platysma contraction to characterize and calculate the movement of the neck and lower-face skin.
In all of the participants a bidirectional movement of the skin was observed: the skin of the lower face and inferior to the jaw-line moved caudally, while the skin of the lower neck moved cephalad. Both movements converged at a line situated at 54±10 percent and 55±8 percent of the length between the clavicle and the inferior base of the ear lobe in men and women respectively (p = 0.70).
The platysma is a bidirectional muscle with a line-of convergence. While the superior portion acts as lip depressor, the lower portion elevates the skin of the upper chest and lower neck. This transition can explain some of the clinically observed adverse effects of neuromodulation of the neck area. It can potentially direct neuromodulation injections to focus above the convergence line to better address lower-face descent.