Hand muscles and skin are innervated by nerves, when the nerve injury will appear skin sensory impairment and loss of muscle function, the hand is generally innervated by three major nerves, the radial nerve, the median nerve and ulnar nerve, the specific manifestations of the nerve injury are as follows: 1, radial nerve: the main innervation of the dorsal side of the tiger’s mouth skin sensation, when the radial nerve injury, the dorsal side of the tiger’s mouth skin sensation of numbness; 2, the median nerve: the skin sensation of three and a half fingers, as well as the muscle movement of the greater pisiform area, the median nerve injury is generally three half-finger skin sensation numbness of the thumb, the extensor function is limited. Median nerve: innervates the skin sensation of three and a half fingers on the radial side, as well as the muscle movement of the big pisiform area, after the median nerve injury is generally the radial side of the three and a half fingers of the skin numbness, the thumb’s extensor function is limited, the ape hand, that is, the big pisiform atrophy of muscle atrophy of the hand is relatively flat posture; 3, ulnar nerve: innervates the ulnar side of the one and a half fingers of the skin sensation, the small pisiform muscles, as well as all of the hand muscle and interosseous muscles, ulnar nerve injury After the damage of ulnar nerve, the skin of one and a half fingers on the ulnar side of the finger can appear sensory numbness, atrophy and functional limitation of the internal hand muscles, showing the eagle claw hand.