Figure 1. Diagrammatic representation of scheme used to quantify changes in the pattern of chest wall motion depicted in figures 4 to 6. A mid-saggital section of the thorax is shown, with end-expiratory (solid lines) and end-inspiratory (dashed lines) positions of the chest wall depicted. Stippled areas indicate edge views of planes used to quantify changes in transverse rib cage area and average diaphragm motion. The arrow indicates the cephalad extent of the area of apposition at end expiration.