Fig. 11. Views of three-dimensional computer designs based on actual measurements of the bronchial system of the ostrich Struthio camelus. The air conduits that are shown include the extrapulmonary primary bronchi (EPPB, filled circles), the intrapulmonary primary bronchi (IPPB, filled squares) and the medioventral secondary bronchi (MVSB, filled triangles) (see also Fig.2). The size and angulation of these air conduits are the most important features in the generation of inspiratory aerodynamic valving (IAV), i.e. the shunting of the inspired air past the openings of the MVSB. (A) Side view of an extrapulmonary primary bronchus, an intrapulmonary primary bronchus terminating in an ostium (asterisk) and three MVSB. (B,C) Views of the air-conduits in the right and left lungs. Note that only the sizes and the geometry at the origins of the MVSB, the most critical areas in IAV, are shown in the constructions. Subdivision and subsequent angulation of the bronchi is evident in Fig.2 and in the actual specimens (Fig.3, Fig.4A, Fig.5).