Functional electrical stimulation (FES) is being successfully used in spinal cord injured (SCI) patients, either for movement restoration or for training purposes. In order to develop viable implanted neuroprostheses as palliative solutions for motor control disabilities, three main challenges have to be tackled: i) a more physiologically-based approach to muscle activation and control; ii) integration of the neural prosthesis control parameters in the numerical modeling and iii) small, reliable, safe, and easy-to-implant devices.