Apparatus for nerve stimulation; Apparatus for the electrical stimulation of groups of muscles; Apparatus for the therapeutic stimulation of the body; Apparatus for the therapeutic stimulation of the muscles; Electrical apparatus for medical purposes for applying therapeutic stimulation to the body; Electro-medical stimulation current apparatus; Medical apparatus for nerve stimulation; Transcutaneous electrical nerve stimulation electrodes; Transcutaneous electrical nerve stimulation instruments; Medical apparatus and instruments; Transcutaneous electrical muscle stimulators