Transmural pressure (TP) measured at various locations along the syrinx in each model (SSED, SSE, and SRE) during coughing: TP ( t ) = Pr, syrinx( t ) - P
( t ) and plotted against time. Positive pressure trace indicates that pressure in the syrinx is greater than the SAS at adjacent sensor locations. Negative pressure trace indicates that syrinx pressure is less than the SAS. Legend symbols identify pressure sensor location. The presence of a SAS stenosis (SSED and SSE) could cause the syrinx to balloon outward at its rostral end and be compressed at the caudal end. When the stenosis was removed (SRE), TPs were smaller and oscillated about zero. SSED, SAE, SSE, and SRE as for Figure 1.