muscles of ventilation [L, musculus + respirare, to breathe] , muscles that provide inspiration, partly by increasing the volume of the chest cavity so that air is drawn into the lungs, including the diaphragm and external intercostal muscles. They are aided during forced breathing by the scalenus muscles, levatores costarum, sternocleidomastoid, pectoralis major, platysma myoides, and serratus superior posterior. Muscles of forced expiration include the external and internal oblique, rectus abdominis, and transverse abdominis.
