Muscles are very important for the movement of joints and aid in bodywork. There are many types of muscles and each of them has its own specific function. When it comes to muscle pain, the common presenting complains are muscular pain, weakness and in severe cases, it can even cause paralysis. However, it is essential to distinguish between a subjective feeling of generalized weakness occurring with fatigue and an objective weakness with loss of muscle power and function. Muscle disorders are very broad and there are many disorders of muscles. Briefly, some of the causes of muscle disorders are injury or overuse such as sprains, strains, cramps, tendonitis, genetic disorders such as muscular dystrophy, cancer of the muscles though it is very rare, inflammations such as myositis, infections of the muscles, certain medications that will cause muscle weakness. Investigations such as electromyography. Muscle biopsy are essential in certain conditions of muscle disorder. The management of muscle disorder varies but the main principles are to relieve the symptoms and treat the underlying causes.