The clinical manifestations of myasthenia gravis are that all skeletal muscles of the body can be involved, but extraocular muscles are the most commonly involved. This can be manifested as drooping eyelids, diplopia, or the whole body muscles can be involved at the same time, aggravated by fatigue, partially recovered after rest, or lighter and heavier. The extent and degree of muscle involvement varies widely. So, what are the clinical manifestations of muscle weakness? Myasthenia gravis is a long-lasting and difficult to treat disease that not only causes physical and psychological pain to the patient, but also brings great repercussions to the family and society. The clinical symptoms include drooping eyelids, diplopia, strabismus, weakness of expression and masticatory muscles, indifference of expression, inability to puff and blow, and weakness of the medulla oblongata muscles, inability to speak, tongue extension, difficulty in eating, choking and coughing. The cause of this disease is systemic, but the affected muscles may have different clinical manifestations depending on their focus. The disease can occur in all age groups, but mostly in the 15-35 age group, with a male to female sex ratio of about 1:2.5. The onset of the disease varies, and is insidious, mainly manifesting as skeletal muscle abnormalities and easy fatigue. As the disease progresses, more of the extraocular muscles can be involved, resulting in diplopia and eventually fixation of the eye. In addition, the medullary innervated muscles, cervical muscles, scapular muscles, trunk muscles and upper and lower limb muscles can be involved. Temporary reduction, remission, recurrence and worsening of the symptoms of muscle weakness often alternate and constitute important signs of the disease. Depending on the extent and degree of muscle involvement, the disease is generally classified into ocular muscle type, medullary muscle involvement type and generalized type. In rare cases, the onset of the disease is rapid, with myasthenia gravis and dyspnea occurring within a few days to a few weeks. Myasthenia gravis in children refers to the onset of myasthenia gravis from neonatal to adolescent age, and is mostly limited to the extraocular muscles, except for the generalized type.