Elastic and contractile properties of muscle

Publisher Website
Google Scholar
Abstract
The introduction of a special class of materials, called ’’contractile’’ into nonlinear continuum mechanics to represent muscular tissue is suggested and the general constitutive equation is given. For application to different muscles, transversely isotropic contractile material is considered, and for a cylinder (model for papillary muscle) and for a spherical shell (model for the left ventricle of the heart), more explicit expressions for the stress–contraction‐strain equations are derived. For the left ventricle an energy density function W is heuristically constructed. Its four constants C, b, β, and Ra can be determined from measurements and are potentially of prognostic and diagnostic value. Energies and pressures calculated with this function for hearts in different conditions of contraction and passive deformation differ, in general, less than 10% from the measured values. An example for a human heart is given. By means of W an exponential function with constants that may come closer to material constants can be constructed.