Aim: Jaw-opening strength is an indicator of swallowing function including hyoid bone elevation. Geniohyoid muscles play an important role during hyoid bone elevation. This study aimed to investigate whether geniohyoid muscle thickness and echo intensity measured by ultrasonography were related to jaw-opening strength.
Material and methods: Sixty-eight participants (39 men) with an average age of 77±7.7 years were recruited from a functional training health care facility. We measured muscle thickness and echo intensity of the geniohyoid muscle on transverse ultrasound images.
Results: Age, calf circumference, grip strength, muscle thickness and echo intensity were significantly associated with jaw-opening strength in univariate analyses. After adjusting for grip strength in multiple regression analysis, geniohyoid muscle thickness and echo intensity were significantly associated with jaw-opening strength (β=0.29 for muscle thickness, β=-0.26 for echo intensity).
Conclusions: There was a positive correlation between geniohyoid muscle thickness and jaw-opening strength; echo intensity negatively correlated with jaw-opening strength. Ultrasound evaluation of geniohyoid muscle status provides important information about maintaining jaw-opening strength.