Ultrasound analysis of tongue, hyoid, and larynx activity during swallowing.

Using real-time ultrasound, the motions of the tongue, hyoid bone, and larynx were monitored and timed during swallowing in ten normal subjects. A well-defined propulsive wave of the tongue was observed during swallowing a 5-cc water bolus. The body of the hyoid bone was identified on the ultrasound scan as a high echogenic area with posterior acoustic shadowing at the tongue base. As the water bolus reached the pharynx, hyoid elevation was visible. Laryngeal motion was monitored by an externally applied pressure transducer and its pressure tracing incorporated into the ultrasound video image.