The left thumb can not make strength to consider and cervical spondylosis, tenosynovitis, hand trauma and other factors related. 1. Cervical spondylosis: especially nerve root cervical spondylosis, due to the protruding cervical intervertebral disc compression of the cervical nerve root, resulting in numbness and weakness of the fingers in the area innervated by the nerve root. 2. Tenosynovitis: Acute or chronic inflammatory reaction of tendon sheath manifests as pain in the hand, limitation of activity, and inability to use force, which is mostly seen in people who have been using their wrists for a long time or excessively. 3. Hand trauma: the left hand due to impact, lifting heavy objects or improper use of force and other reasons leading to left finger injury, thumb pain, weakness. The left thumb can not make strength may also exist cerebrovascular lesions and other reasons, such as finger pain, weakness of the symptoms continue to be unrelieved, it is recommended to consult a doctor in time, improve the examination to clarify the cause of the disease, to give targeted treatment or treatment.