This study provides novel longitudinal evidence that the temporalis and masseter muscles undergo measurable atrophy in adulthood. Volumetric reductions corroborated thickness losses and revealed the temporalis as particularly vulnerable. These changes help explain aesthetic features such as temporal hollowing and jawline descent, underscoring the contribution of muscle loss to facial aging and motivating further investigation into preventive or restorative approaches.
Sifil et al. (2026) studied this question.