USCLES OF DEEP INSPIRATION AND EXPIRATION Deep breathing uses forceful contractions of the inspiratory muscles and additional accessory muscles to produce larger changes in the wolume of the thoracic cavity during both inspiration and expiration DEEP INSPIRATION DEEP EXPIRATION Scalene Sternocleidomastoid Internal intercostal muscles External intercostal muscles Diaphragm External oblique Rectus abdominis nternal oblique Transversus abdominis Click the illustration to see deep breathing