Meeting Abstract

P3.108A  Sunday, Jan. 6  Mechanical Behavior of the Cartilaginous Nasal Septum AL DAYEH, A.; HERRING, S.W.*; University of Washington, Seattle; University of Washington, Seattle herring@uw.edu

Damage to the nasal septum collapses the snout, perhaps because structural support is lost. During mastication in pigs (Sus scrofa), the dorsal septum is compressed anteroposteriorly (A-P) (Al Dayeh et al. 2009). Therefore, the septum is not a dorsoventral (D-V) strut, but it could be resisting dorsal bending of the snout or acting as an A-P strut. Bending predicts dorsal A-P compression and ventral A-P tension. A strut function predicts A-P compression at all levels. These two models were assessed by mechanical testing of porcine septal samples along the A-P or D-V axes in compression and tension (n=13-18). After preloading, specimens were strained non-destructively up to 10% to calculate stiffness; relaxation stress was recorded for 30 (tension) or 120 (compression) sec; finally, specimens were loaded to failure. Overall, the septum was stiffer (3.35 vs. 0.70MPa) and stronger (2.2 vs. 1.4MPa) in compression than tension, but deformed much less at failure (30% vs. 128%). Stress relaxation was greater under compression but took longer. Support for the bending model was poor. A-P compressive stiffness was insignificantly greater dorsally than ventrally; tensile stiffness was not greater ventrally. Support for the strut model was better only if the anteriormost location (tested D-V) was ignored, in which case compressive stiffness and strength were significantly greater A-P than D-V. The anteriormost region was uniquely strong and flexible, presumably because of its connection with the snout disc. Thus, the septum is adapted to receive A-P compression and the anteriormost region is specialized. Nevertheless, the low stiffness and high strain observed throughout the septum imply that it has no important role in structural support of the snout other than as a stress dampener. Its most important function may be growth. Supported by PHS DE08513.