A79-08 Role of the Mylohyoid Muscle in Obstructive Sleep Apnea Pathogenesis and Treatment Heterogeneity: A Review

Abstract Rationale The pathophysiology of obstructive sleep apnea (OSA) is linked to the failure of upper airway dilator muscles to maintain pharyngeal patency during sleep. Research and therapeutic development have overwhelmingly focused on the genioglossus (GG) muscle, yet the mylohyoid muscle (MM) remains a significantly under-investigated component. The MM forms the muscular floor of the mouth and acts synergistically with the geniohyoid to stabilize the hyoid bone and tongue. We hypothesize that dysfunction of the MM, as a component of the suprahyoid muscle complex, contributes substantially to airway collapse and represents a novel target for understanding OSA heterogeneity. Methods A structured PubMed review was performed to identify articles using the MeSH term obstructive sleep apnea and the following key terms: “mylohyoid muscle”, “mylohyoid”, “floor of mouth”, “suprahyoid muscles”. This abstract presents a synthesis of evidence derived from a critical review of anatomical, physiological, and clinical studies. We analyzed existing data on suprahyoid muscle group function, electromyographic (EMG) studies of upper airway muscles, and histological evidence of myopathy in OSA patients. Results Three primary roles for the MM effecting OSA were found: 1) anatomical structural foundation when activated for the GG, 2) action primarily at the level of the epiglottis, 3) aids in muscular coordination of airway patency. The mylohyoid forms a muscular anatomical foundation that provides essential structural support for the tongue. Its contraction elevates the hyoid bone, tensing the floor of the mouth and facilitating anterior displacement of the tongue base. Therefore, providing a more rigid base for GG action. Obstructions at the level of the epiglottis was more strongly associated with tonicity of the MM. Additionally, the coordination of airway patency relies on the interaction of multiple dilator muscles. Conclusions The MM is an important modulator of upper airway patency. The historic focus on the genioglossus has overlooked the role of the mylohyoid muscle in providing structural support and its contribution to pharyngeal collapse. Future research of targeted EMG studies isolating the mylohyoid during sleep is necessary to clarify its role and explore its potential as a novel diagnostic and therapeutic target for obstructive sleep apnea beyond current myofunctional therapies. This abstract is funded by: None