Fig. 4

Reduction in trachealis muscle nonlinear elastic properties to simulate tracheal posterior wall weakening. a Intact muscle nonlinear elastic Ogden fit with arrows indicating initial reduction in properties to first a = 1, b = 7 from eq. 1 and subsequently to a = 1, b = 1 from eq. 1. b plot of ratio of exhalation to deformed tracheal lumen area for a = 1, b = 7 muscle properties. Although there is increasing reduction in tracheal area up to 32 mm malacic segment, no instability occurs as with anterior wall property reduction. c plot of ratio of exhalation to deformed tracheal lumen area for a = 1, b = 1 muscle properties. Again, there is increasing reduction in tracheal area up to 32 mm malacic segment, but no instability occurs