Woke up in the morning ring finger can not straighten may be due to sleep posture improper compression of the ulnar nerve, may also be tenosynovitis, hand extensor tendon injury, rheumatoid arthritis and other pathologic factors. 1. Improper sleeping position: because of the improper sleeping position at night to compress the arm, resulting in body compression of the ulnar nerve, resulting in numbness of the ring finger, the phenomenon of straightening, appropriate activities of the arm, wrist and fingers can eliminate symptoms. 2. Tenosynovitis: aseptic inflammation due to repeated friction between tendons and tendon sheaths as a result of prolonged strenuous exercise or repeated fine movements, with the main clinical manifestations of localized soreness, swelling and pain, radiating pain, and limitation of finger joints. 3. Extensor tendon injury of hand: patients with extensor tendon injury of hand usually have obvious history of hand trauma, mostly open wounds, often combined with nerve and blood vessel injuries or bone and joint injuries. The main manifestations are swelling, pain, functional limitation and difficulty in finger extension. 4. Rheumatoid arthritis: it is an autoimmune disease with erosive and symmetrical arthritis as the main clinical manifestation, which can cause destruction of articular cartilage and bone, and ultimately lead to joint deformity and loss of function, and can occur in small joints of the limbs, swelling and pain, morning stiffness and other symptoms. Wake up in the morning ring finger can not straighten in addition to the above common causes, may also be due to osteophytes, fractures and other causes, it is recommended that the ring finger can not straighten the patient if you can not improve the cause of the disease, should consult a doctor to clarify the cause of the disease, so as not to delay the condition.