Muscle weakness is a lack of muscle strength. Its causes are many and can be divided into conditions that have either true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, including<unk>  dystrophy and inflammatory myopathy. It occurs in neuromuscular junction disorders, such as myasthenia gravis. Muscle weakness can also be caused by low levels of potassium and other electrolytes within muscle cells. It can be temporary or long-lasting (from seconds or minutes to months or years). The term myasthenia is from my- from Greek μυο meaning "muscle" + -asthenia ἀσθένεια meaning "weakness".
symptom of Duchenne muscular dystrophy
symptom of Myotonic dystrophy
symptom of Romano–Ward syndrome
symptom of Amyotrophic lateral sclerosis
symptom of Myasthenia gravis
symptom of Multiple sclerosis
symptom of Dermatomyositis
symptom of Oculopharyngeal muscular dystrophy