Pathology of muscle and motor units

Throughout this issue the point has been made repeatedly that "normal" human muscle is mutable and that consequently physical therapists should consider the muscular component in the evaluation and treatment of almost every patient. Other articles in this issue have described the changes that take place in normal muscle in response to a number of stimuli. The following article deals with muscle from a different orientation: what is found when diseases primarily affect muscle. The structural changes are examined that occur in response to many neuromuscular diseases. Frequently, the diagnosis of different diseases and the clinical management of the conditions by stages are based on the types of alterations described. This review provides the therapist with the background knowledge to better understand the diagnoses of neuromuscular diseases and with a concise resource when reading the literature concerning muscle pathology and when evaluating or treating patients with pathological conditions of muscle.