OpenSim musculoskeletal models of the head and neck can provide information about muscle activity and the response of the head and neck to a variety of situations. Previous models report weak flexion strength, which is partially due to lacking moment generating capacity in the upper cervical spine. Previous models have also lacked realistic hyoid muscles, which have the capability to improve flexion strength and control in the upper cervical spine. Suprahyoid and infrahyoid muscles were incorporated in an OpenSim musculoskeletal model of the head and neck. This model was based on previous OpenSim models, and now includes hyoid muscles and passive elements. The moment generating capacity of the model was tested by simulating physical experiments in the OpenSim environment. The flexor and extensor muscle strengths were scaled to match static experimental results. Models with and without hyoid muscles were used to simulate experimentally captured motions, and the need for reserve actuators was evaluated. The addition of hyoid muscles greatly increased flexion strength, and the model is the first of its kind to have realistic strength values in all directions. Less reserve actuator moment was required to simulate real motions with the addition of hyoid muscles. Several additional ways of improving flexion strength were investigated. Hyoid muscles add control and strength to OpenSim musculoskeletal models of the head and neck and improve simulations of head and neck movements.

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Simulating impacts to the head that are likely to cause concussion contributes knowledge to inform efforts to reduce head injury risk in sports. Previous studies used generic models and potentially missed subject-specific factors, which when combined with experimental data may offer additional insights about an individual’s risk. This study details methods for creating more subject-specific OpenSim models of the head and neck, which can be used in future studies to evaluate head injury risk during impacts. A generic model was scaled to match subject height and weight using data available from the literature. Muscle strength and passive properties were also scaled in order to reproduce experimental data obtained during safe impacts to the head. The average error between experimental and simulation kinematic values was under 15% for all but one of the subject-models. By applying the methods presented in this study, future work could include using subject-specific models to assess individual athletes and generate personalized training protocols to help prevent injury. Future work could also include subject-specific models to investigate the effects of posture, startle response, and auditory warnings on head injury metrics.