Peripheral nerve entrapment neuropathies currently occur as 'tunnel syndromes' (cf. carpal tunnel syndrome). The present study focuses on the anatomical features of the pronator teres muscle and the median nerve (innervating forearm flexors), investigated in normal human anatomical specimens by means of dissection, morphometry and roentgenphotogrammetry. In planar movement of the human hand, e.g. a horizontal shift over a flat surface, rotation of the humerus is involved. Forward movement implies an internal rotation, backward movement an external rotation. This external rotation imposes some degree of pronation on the forearm. As a consequence, excessive repetitive forward-backward shifting of the hand (palm downwards) may result in stressing the m.pronator teres, and may eventually lead to pathological conditions like repetitive strain injuries (RSI) as well as entrapment neuropathies. Holding the hand with the palm down during prolonged time can induce muscle fatigue, as well as muscle tension, within the pronator teres muscle. Part of such tension can be explained on the basis of active muscle insufficiency. Application of vibrostimulation treatment over a period of weeks therefore, recently proved to be succesful in a majority of RSI-patients.