Figure 2b. (a) Diagram shows that during normal inspiration and expiration, there is dilation and collapse of the airways. This is most obvious in distal airways. Collapse in infant airways is greater than that in adult airways because cartilaginous soft tissues supporting the airways are more compliant in children. This is illustrated on (b) a lateral chest radiograph of an infant obtained near the end of normal expiration. The trachea (arrows) collapses to a much smaller diameter during normal expiration.