Simulation of Anterior Biting Behaviours: Surface EMG and Strain Mapping of Craniofacial Responses

Reconstructing the behaviours of extinct hominin species has long relied on evidence from multiple disciplines, including archaeology, dental microwear analysis, and skeletal anatomy. Within anatomical studies, variation in craniofacial form among humans and other hominins is often interpreted as reflecting differences in habitual behaviours. One proposed explanation for this variation is anterior dental loading, in which the skull is thought to have adapted to repeated or heavy forces applied to the anterior dentition during feeding or paramasticatory activities. Finite element analysis (FEA) has increasingly been used to test this hypothesis by modelling the skull’s mechanical response to forces applied during anterior dental loading. However, interspecific comparisons have yet to identify any hominin species that appears particularly well adapted to such loading, raising questions about whether methodological limitations in FEA studies may have influenced these results.
This thesis investigates one such limitation: the potential role of neck musculature in counteracting head flexion during biting tasks. The first part of the research examines whether including neck muscles in FEA models influences craniofacial strain patterns, demonstrating that their inclusion substantially alters strain magnitude and distribution. The second part records in vivo surface electromyographic data from the neck and masticatory muscles of a modern human during anterior pulling and clenching tasks to quantify muscle activation under realistic behavioural conditions. These data confirm that the neck musculature is actively engaged during anteriorly directed loading of the dentition.
Overall, the findings highlight that finite element models used to simulate anterior dental loading, and even standard vertical biting, should incorporate neck musculature to improve their biomechanical validity and enhance the accuracy of interpretations in craniofacial functional studies.