A Computational Model Reveals How Varying Muscle Activation in the Lateral Pharyngeal Wall and Soft Palate Differentiates Velopharyngeal Closure Patterns.

Abstract

Purpose: Finite element (FE) models have emerged as a powerful method to study biomechanical complexities of velopharyngeal (VP) function. However, existing models have overlooked the active contributions of the lateral pharyngeal wall (LPW) in VP closure. This study aimed to develop and validate a more comprehensive FE model of VP closure to include the superior pharyngeal constrictor (SPC) muscle within the LPW as an active component of VP closure.

Method: The geometry of the velum and the lateral and posterior pharyngeal walls with biomechanical activation governed by the levator veli palatini (LVP) and SPC muscles were incorporated into an FE model of VP closure. Differing muscle activations were employed to identify the impact of anatomic contributions from the SPC muscle, LVP muscle, and/or velum for achieving VP closure. The model was validated against normative magnetic resonance imaging data at rest and during speech production.

Results: A highly accurate and validated biomechanical model of VP function was developed. Differing combinations and activation of muscles within the LPW and velum provided insight into the relationship between muscle activation and closure patterns, with objective quantification of anatomic change necessary to achieve VP closure.

Conclusions: This model is the first to include the anatomic properties and active contributions of the LPW and SPC muscle for achieving VP closure. Now validated, this method can be utilized to build robust, comprehensive models to understand VP dysfunction. This represents an important advancement in patient-specific modeling of VP function and provides a foundation to support development of computational tools to meet clinical demand.