A Biomechanical Modeling Study of the Effects of the Orbicularis Oris Muscle and Jaw Posture on Lip Shape

Abstract

Method: Our methodology is based on computer simulations with a sophisticated biomechanical model coupling the jaw, tongue and face. First, the influence of Orbicularis Oris (OO) muscle geometry is analyzed. We assessed how changes to the OO anatomical implementation, in terms of depth (from epidermis to the skull) and peripheralness (proximity to the lip horn center), affected lip protrusion, lip spreading and lip area. Second, we evaluated the capability of the lip/jaw system to generate protrusion and rounding, or labial closure for different jaw heights.Results: (1) A highly peripheral and moderately deep OO implementation is most appropriate for achieving protrusion and rounding; (2) a superficial implementation facilitates closure; (3) protrusion and rounding requires a high jaw position; (4) labial closure is achievable for various jaw heights.Conclusions: Our results provide a quantitative assessment of how physical characteristics of the speech motor plant can determine regularities and variability in speech articulations across humans and over time.

Pushes and pulls from below: Anatomical variation, articulation and sound change

“…The idea that human vocal tract variation biases phonological systems has been around for a long time (e.g., Vendryès 1902;Meillet 1937;Darlington 1947;Zipf 1949;Brosnahan 1961;Allott 1994), but, given the incredible causal complexity behind the organization of phonological systems, coupled with the perceived potential racist connotations, substantial proof has been wanting. Recent developments in vocal tract imaging, large scale typological data analysis, and biomechanical modeling suggest that a revisitation of this hypothesis is warranted (e.g., Stavness et al 2013;Dediu et al 2017), especially as more data are emerging which show that individual differences in phonetic behavior are linked with anatomical variation (Brunner et al 2009;Weirich & Fuchs 2011;Stone et al 2012).…”

Predicting 3D lip movement using facial sEMG: a first step towards estimating functional and aesthetic outcome of oral cancer surgery

“…Functional prediction using virtual surgery is complex and involves several aspects of patient-specific anatomical geometry, biomechanical tissue properties, branching and distribution pattern of the nervous system and the muscle activation signals that control a particular function. Biomechanical modelling, including the muscular system, in the oral and oropharyngeal region, has been the subject of ongoing research [10, 16, 18, 23]. …”

Soft Tissue Finite Element Modeling and Calibration of the Material Properties in the Context of Computer-Assisted Medical Interventions

“…An additional isochoric term is included in the strain energy function, to account for lateral normal stiffness. Figure 5 illustrates such muscle action with the deformations induced by the activation of the orbicularis oris peripheral muscle which is a sphincter muscle running around the lips and responsible for lip protrusion (Nazari et al, 2011b ;Stavness et al, 2013)). The idea is to use such a model to predict the aesthetic and functional consequences of maxillary and mandible bone repositioning.…”