A finite element muscle model has been designed with the Usermat functionality of ANSYS® multiphysics software. It is represented by a transversely isotropic material which strain energy is a function of I4 and I5 invariants of the Cauchy-Green strain tensor in the direction of muscle fibers. Muscle activation is accounted for by adding an active stress to the Cauchy stress in the direction of fibers. This active component introduces the force as a function of current length of a muscle. An additional isochoric term is included in the stress energy function, to account for lateral stiffness increase due to muscle activation. This element has been tested in an existing finite element model of the human face. In this model muscle elements are implemented in the mesh according to anatomical facts and on the basis of information extracted from CT scans of the face of speaker. A nearly incompressible hyperelastic material accounting for transversely isotropic behavior is used to model the mechanical properties of passive surrounding tissues. Some typical speech gestures have been simulated and evaluated on the basis of experimental data.