We introduce a biomechanical model of oropharyngeal structures that adds the soft-palate, pharynx, and larynx to our previous models of jaw, skull, hyoid, tongue, and face in a unified model. The model includes a comprehensive description of the upper airway musculature, using point-to-point muscles that may either be embedded within the deformable structures or operate externally. The airway is described by an air-tight mesh that fits and deforms with the surrounding articulators, which enables dynamic coupling to our articulatory speech synthesizer. We demonstrate that the biomechanics, in conjunction with the skinning, supports a range from physically realistic to simplified vocal tract geometries to investigate different approaches to aeroacoustic modeling of vocal tract. Furthermore, our model supports inverse modeling to support investigation of plausible muscle activation patterns to generate speech.