Some patients in the clinic say that they have weakness or muscle atrophy in their limbs, considering some manifestations of myasthenia gravis. In fact, from clinical analysis, there are many kinds of diseases that can cause muscle weakness, including both orthopedic problems and problems in other departments, for example, the following: 1, orthopedics is common in the spinal cord nerve damage and lead to weakness, such as common cervical spondylosis, including cervical disc protrusion or cervical spinal stenosis, etc. 2, lumbar spine lumbar disc protrusion, lumbar spinal stenosis, are due to the cervical and lumbar spinal cord 3. peripheral nerves, such as the ulnar, radial, and median nerves in the upper limbs, the common peroneal nerve in the lower limbs, and even the sciatic nerve, which are like the middle reaches of a river, may also cause muscle weakness if something goes wrong. 4. Inflammation of the spinal cord, such as myelitis or other problems, or even endocrine electrolyte disorders, such as potassium, sodium, calcium, chloride, etc., may also cause muscle weakness. Therefore, to determine the cause of myasthenia gravis, it is necessary to combine the patient’s medical history, clinical examination, and many necessary auxiliary tests to make a comprehensive analysis and judgment, and it may even require consultation and consultation among many departments to find the specific cause.