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Title:3D mathematical model of the hyoid bone and attached muscles during swallowing
Author(s):Zu, Yihe
Director of Research:Perlman, Adrienne L.; Hasegawa-Johnson, Mark A.
Doctoral Committee Member(s):Hasegawa-Johnson, Mark A.; Sutton, Bradley P.; Husain, Fatima T.; Loucks, Torrey M.J.
Department / Program:Speech & Hearing Science
Discipline:Speech & Hearing Science
Degree Granting Institution:University of Illinois at Urbana-Champaign
three-dimensional (3D)
Mathematical model
Magnetic resonance imaging (MRI)
submental muscles
Abstract:Dysphagia has negatively affected the quality of life or even caused death for many head and neck cancer patients. Consequently, it is critical that scientists investigate the function of normal and abnormal swallowing in an effort to determine what can be done to reduce health risks. In order to better understand the physiology of a safe swallow, the purpose of this study was to use magnetic resonance images and mathematical tools to determine the actions of hyoid displacement and upper esophageal sphincter opening secondary to the hyoid displacement. Methods: Four healthy male adults participated in this study. Each subject lay in a MRI scanner, and was given 5 ml, 10 ml, 15 ml and 20 ml of water to swallow, four times each. During swallowing the 3D structural and 2D dynamic MRI were collected. The origin and insertion of the submental muscles (SM), posterior belly of digastric (PBD), and infra-hyoid muscles (IH) were measured. The anterior and posterior boundaries of upper esophageal sphincter (UES) and the antero-inferior corner of cervical vertebrae 7 (C7) were also measured. The soft tissue between the hyoid bone and the anterior UES boundary was denoted as TH; the soft tissue between the posterior boundary of UES and C7 was denoted as RF. Then, using a lambda model treating SM, PBD, IH, and TH as active springs, and treating UES and RF as passive springs, the muscle force changes during swallowing were simulated. Results: The timings when SM and TH generate their maximum forces were found to have positive effect on UES maximum opening. The SM mm. were the principle muscle source for both opening and elevating the UES. TH was more closely related to laryngeal elevation than to UES opening. IH mainly contributed to stabilization of the hyoid bone as the SM and PBD mm. move the hyoid bone superiorly; and, at the same time the IH mm. worked with TH to help protect the larynx. PBD force contributed to the maximum IH length at the initial stage of the swallow, however, the force from the PBD was not large enough to elongate the IH sufficiently to let the UES reached its maximum superior position. In addition, it is likely to contribute to fixing the UES posterior wall to the cervical spine while the UES is opened by SM contraction and the entire UES sliding along the cervical spine. Conclusion. The main finding of this study is the critical function of SM on a safe swallow. This provides critical information to otolaryngologists (ENT), speech language pathologists (SLP) and other related professions that may enable future treatments targeting this muscle.
Issue Date:2012-02-06
Genre:Dissertation / Thesis
Rights Information:Copyright 2011 Yihe Zu
Date Available in IDEALS:2012-02-06
Date Deposited:2011-12

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