A review of the literature on the pathophysiology of upper extremity muscle disorders
(UEMDs) was performed. An overview is given of clinical findings and hypotheses on the
pathogenesis of UEMDs. The literature indicates that disorders of muscle cells and
limitations of the local circulation underlie UEMDs. However, these disorders identified do
not necessarily lead to symptoms. The following mechanisms have been proposed in the
literature:(1) selective recruitment and overloading of type I (Cinderella) motor units;(2) intra …