The goal of the project is to investigate new computational tools for understanding normal upper airway mechanics and the pathophysiology of obstructive sleep apnea (OSA), a disorder characterized by repetitive pharyngeal collapse and occlusion during sleep. To relate the airway mechanical parameters to anatomy, and explore the roles of primary muscle properties, airway shape and structure, a new computational system for modeling of rat upper airway passive mechanics based on magnetic resonance imaging (MRI) was developed. The model is capable of computing stress and strain distributions under arbitrary loading, and dynamic animation of three-dimensional airway motion.