North Seattle College EMT Entrance Practice Exam

The intercostal muscles are the muscles located between the ribs that play a crucial role in the mechanics of breathing. There are two main sets of intercostal muscles: the external intercostals and the internal intercostals. During inhalation, the external intercostal muscles contract, which elevates the ribs and expands the thoracic cavity, allowing air to enter the lungs. Conversely, during exhalation, the internal intercostals can contract to depress the ribs and help push air out of the lungs, especially during forceful breathing. These muscles are essential for efficient respiration, as they assist in changing the volume of the thoracic cavity. The diaphragm, while also critical in the breathing process, is a separate muscle located beneath the lungs that primarily handles the downward movement during inhalation. The hyoid muscles, although involved in movements of the throat and swallowing, do not play a direct role in respiration, nor do thoracic muscles specifically as a distinct category related to respiration. Thus, the intercostal muscles are the correct answer due to their direct involvement in the mechanics of breathing.