Injury to the median nerve of the hand is manifested as: thumb abduction dysfunction and thumb and index finger pinching dysfunction due to thumb short abductor palsy, palmar radial half, thumb, index, middle and ring finger radial half palmar surface, thumb interphalangeal joint and index, middle and ring finger radial half proximal interphalangeal joint with distal sensory deficits, mainly manifested as loss of sensation in the index finger. So what is the cause of loss of sensation in the index finger? Here is a brief introduction. The most common cause of brachial plexus injury is a strain injury. Most brachial plexus injuries in adults (about 80%) are caused by car accidents. If a motorcycle collides with a car, a motorcycle hits a roadside obstacle or a tree, the driver is injured and falls to the ground, the head and shoulders hit the obstacle or the ground, so that the head and shoulders are separated, the brachial plexus nerve is overstretched, the milder the nerve concussion, temporary dysfunction, the heavier the nerve axon rupture, nerve root cadre rupture, loss of function. Median nerve injury is often caused by laceration, and the injury site is mostly in the wrist or forearm, with smaller injuries in the upper arm or axilla. In the upper arm, the nerve can be injured by relatively superficial lacerations, tight tourniquets, humeral fractures, and near the axilla, the ulnar nerve, musculocutaneous nerve, and brachial artery are often involved at the same time. Fractures of the lower humerus and forearm fractures can be combined with median nerve injuries. Ischemic contractures are also often combined with median nerve injuries.