The genioglossus is an extrinsic muscle of the tongue. It is a large, thick muscle, making a significant contribution to the shape of the tongue.
The genioglossus has two primary attachments. It arises from the mandibular symphysis and inserts onto the body of the hyoid bone and the entire length of the tongue. Its main function is to protract (‘stick the tongue out’) and depress the tongue. The hypoglossal nerve provides the genioglossus with its primary innervation, while the lingual artery and tonsillar artery provide the muscle with its primary blood supply.
Figure 1 illustrates the extrinsic muscles of the tongue, demonstrating the genioglossus and other muscles such as the styloglossus and the hyoglossus. Notably, the palatoglossus muscle is not included in this illustration.
The genioglossus contributes to a number of important actions, enabling its role in swallowing, speaking, and respiration. Inadequate genioglossus action can lead to problems with these activities, contributing to various speech and eating disorders.
Disorders of the genioglossus can also put an individual at an increased risk for obstructive sleep apnea (OSA). OSA is a condition in which an individual is unable to maintain open airways during sleep, leading to episodes of hypoxemia and fragmented sleep. Research suggests that genioglossus weakness plays a role in OSA, leading to narrowing and collapse of the pharyngeal airways.
It is important to note that the genioglossus is often weakened in individuals with OSA, making it difficult to use the muscle as a treatment for the condition. Several techniques have been proposed to improve genioglossus action in OSA, including electrical stimulation, orthopedic appliances, and vocal exercises; however, their efficacy is unclear.
The genioglossus is an important extrinsic muscle of the tongue. It is responsible for protraction and depression of the tongue, and plays a role in a number of activities such as swallowing, speaking, and respiration. Weakness of the genioglossus can contribute to a number of disorders, including speech and eating disorders, and can increase an individual’s risk for obstructive sleep apnea (OSA). While there are treatments designed to improve genioglossus action, further research is needed to determine their efficacy.
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