Obstructive sleep apnea (OSA), the intermittent cessation of breathing during sleep, occurs when the upper airway tissues (e.g., tonsils, fatty tissue) repeatedly collapse into the upper airway and partially or fully block airflow. The collapsibility of the upper airway in people with OSA is believed to occur because the upper airway muscles relax excessively during sleep, which allows structures supported by the muscles to collapse into the upper airway. Some research indicates that altered neuronal activation may contribute to the reduced tone of the upper airway muscles. Much of this research has focused on innervation of dilator muscles such as the genioglossus muscle (which forms the bulk of the tongue). However, another structure that contributes to obstruction is the soft palate. In recent years, scientists have begun examining whether neuronal injury in the soft palate muscles could contribute to OSA.