These findings can be used to assist head and neck cancer treatment planning and counseling. Because hyoid measurement methods influence research conclusions, this aspect of design should be considered when interpreting research findings.

Problem A 3D dynamic model of supra and infrahyoid muscle groups was developed to provide information relative to the extent of muscle contraction. This model can provide valuable information relative to the physiology and pathophysiology of speech production, swallowing, and effects of surgical reconstruction. The rotation of the 3D model permits the viewer to appreciate the internal anatomy from several vantage points. Transparency can be used to study underlying anatomy without change the surroundings. In this study, a 3D dynamic model of suprahyoid and infrahyoid muscle groups during swallowing was created based on still 3D and dynamic MRI. This model will be further developed to examine the effects of muscle forces on functional changes after head and neck surgery. Methods 3D MRI of head and neck area were used to reconstruct 3D polygonal meshes of hyoid muscle groups, hyoid bone, mandible, and larynx. Measurement was performed using Amira 4.1. The polygonal meshes were imported in to Alias Maya 8.5. By mapping the dynamic MRI of the swallow, the muscle meshes were reshaped to generate a 3D movie of swallowing. Results Using MR images, an accurate and realistic computer reconstruction of supra and infra hyoid muscles, in situ, was constructed. A 3D movie was created to demonstrate the anatomy, larynx, and hyoid displacement in all directions. Conclusion MRI provides high quality soft tissue information. 3D modeling using MRI provide muscle information in situ. The dynamic movie created the opportunity for researchers and physicians to observe anatomical changes in all coordinate planes. These offer a promising future toward increased understanding of head and neck physiology and pathophysiology. Significance This is the first 3D model to provide dynamic information on the hyoid muscle groups. It will eventually include forces that will animate functional change after surgical reconstruction. Support NIH-NIDCD, Award No. PHS 1 R01 Dc005603-01A2.