Muscles involved in breathing. The main respiratory muscles are the intercostals and diaphragm, but during exercise other muscles may contribute to ventilation. During inhalation, contractions of the scaleni and sternocleidomastoids assist the actions of the external intercostals and diaphragm, to increase the thoracic cavity and draw air into the lungs. During exhalation, contractions of the abdominal muscles combine with contractions of the internal intercostals to reduce the thoracic cavity and force air out of the lungs.
Subjects: Sports and Exercise Medicine.