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Effects of introducing gap constraints in the masticatory system: A finite element study
Published in J. Belinha, R.M. Natal Jorge, J.C. Reis Campos, Mário A.P. Vaz, João Manuel, R.S. Tavares, Biodental Engineering V, 2019
S.E. Martinez Choy, J. Lenz, K. Schweizerhof, H.J. Schindler
The jaw muscles present in our model are the lateral pterygoid, digastric, masseter, temporalis and medial pterygoid. Muscles are composed by two entities, one representing the fibrous part and the other the tendon. Hill’s muscle model was employed to represent the fibers and an inextensible wire to represent the tendons, because they undergo very small deformation and may, for this reason, be ignored. In total, eight truss elements represent the following muscles (on each side): Anterior and posterior temporalis, superficial and deep masseter, superior and inferior lateral pterygoid, medial pterygoid and digastric. Muscle fibers are composed by myofibrils. In the case of striated muscles, the myofibrils are arranged into contractile units called sarcomeres. Forces produced by this type of muscle are influenced by the length of their sarcomeres (force-length relationship) and their contraction velocities (force-velocity relationship). Additionally, the muscle exhibits a passive elastic force when stretched. In our model, the characteristic curves of the muscle are taken from van Ruijven & Weijs (1990).
Modeling and simulation of musculoskeletal system of human lower limb based on tensegrity structure
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Zhanxi Wang, Chaoran Yang, Kang Feng, Xiansheng Qin
The Hill muscle model is used in analysis of muscle mechanics involved in this paper (Hill 1938). Assuming that there is a linear relationship between length of each muscle and joint angle, the relationship between muscle length and joint angle n (n, n, and Figure 1), and the muscle force model equation is derived by Van Soest, Bobbert, and Clean (van Soest and Bobbert 1993; Mclean et al. 2003; Jovanovic et al. 2015). The basic muscle force equation is a is the excitation of muscle,
Effect of tendon length in the estimation of musculotendon forces during an elbow flexion-extension
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
O. Jemaa, S. Bennour, D. Daney, L. Romdhane
Figure 3 illustrates the muscle forces obtained using Hill’s muscle model and musculotendon model. The results obtained show the influence of the tendon in the movement of elbow flexion-extension. The major difference is the development of passive force in the muscle model. Based on the force-length muscle relationship, the presence of a passive force means that the muscle length is longer compared with the isometric muscle length. Contrariwise, the variation of tendon length, in the musculotendon model, enables the muscle to contract at a more optimal velocity and optimal length. Consequently, when muscle working in this optimal zone, the activation needed to developed the musculotendon forces will be lower than the present in the muscle model.
A comprehensive and volumetric musculoskeletal model for the dynamic simulation of the shoulder function
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Fabien Péan, Christine Tanner, Christian Gerber, Philipp Fürnstahl, Orcun Goksel
The Finite Element (FE) method is a robust and well-known approach used for simulation of deformable objects. Muscles can be represented as volumes in the model, allowing to overcome the aforementioned limitations posed by line-segment models. FE models have been used thoroughly to study the shoulder (Zheng et al. 2017; Webb et al. 2014). However, most works in the literature consider only a limited number of muscles, which cannot be representative of the complex shoulder and faithfully model its motion, and without any active control through inverse-dynamics. The modelling of active contraction of fibers in a FE model can be incorporated by choosing an appropriate constitutive model of the muscle material integrating the active contraction part in the 3 D continuum level (Blemker et al. 2005; Weickenmeier et al. 2014). The fibers directions are then discretized at each integration point of the element during the assembly procedure. The alternative approach consists in using separate discretizations for the fibers and its embedding tissue matrix (Berranen et al. 2014; Hedenstierna et al. 2008). In this approach, fibers are usually defined individually as 1 D wire-segments using the three-element Hill muscle model, surrounded by a volumetric FE mesh. Many fiber directions are integrated per element. When no DTI image is available to obtain specific fiber directions, solving the heat equation on the underlying FE mesh between muscle origin and insertion can offer an approximation of fiber directions throughout muscles (Choi and Blemker 2013). Several muscle models above, such as springs, embedded springs or continuum based materials, are implemented in the powerful and flexible multi-body biomechanical simulation framework, Artisynth (Lloyd et al. 2012), which we utilize in this work. Artisynth allows for coupling rigid (bone) models with deformable (muscle) models, which can also be activated and kinematics-controlled.