Biomedical Engineering Reference
In-Depth Information
Neuro-Physiological Model of MU Recruitment
Control of the exerted force through mechanisms of recruitment and rate coding
Neuro-physiological model based on the size principle (Henneman et al., 1965 )
Determination of the firing times of each MU (Fuglevand et al., 1993 )
firing times
Electrophysiology of a Single Muscle Fiber
Computes the electrophysiological changes within sarcomeres along an en-
tire skeletal muscle fiber due to a stimulus originating at the fiber midpoint
at the time determined by the recruitment model. The electrophysiological
changes are caused through the propagation of the action potential, which
is simulated by solving the
Bidomain Equations
- Continuum representation of bio-electrical behavior of active tissue
- Describes the propagation of action potentials along a muscle fiber
- The diffusive behavior of the action potential propagation is coupled
with the (cellular) reactions stemming from the underlying electro-
physiological model
Hodgkin-Huxley-Like Cellular Model (here, Shorten et al., 2007 )
- Describes the electrophysiological behavior of a half-sarcomere
- Mathematically represented through a set of coupled nonlinear ODEs
- Different versions of the model for fast- and slow-twitch fibers
- The cell model includes cellular mechanisms of muscle fatigue
- Model parameters are validated against experimental work (mouse)
A 1 ,A 2
actual configuration
Continuum-Mechanical Skeletal Muscle Model
Computes the exerted muscle force based on the electrophysiological state of the fibers
(due to stimulation) and displacement boundary conditions.
The second Piola-Kirchhoff stress tensor of Eq. ( 8.1 ) is modified to contain concen-
trations of attached myosin heads in the pre-/post-powerstroke state ( A 1 , A 2 ).
The governing equations of finite elasticity are discretized using tri-quadratic La-
grange FE basis functions for the displacement and tri-linear ones for the pressure.
A homogenization is performed to bridge the scales between the cellular level and the
organ level (whole muscle)
see also Sect. 8.4 .
Fig. 8.1 Overview on the computational model to link motor unit recruitment with the continu-
um-mechanical model of a whole skeletal muscle
 
Search WWH ::




Custom Search