<s>[INST] context: Injury to midarm fracture to mid shaft of humerus (at lower pa of radial groove) resulting in High Radial nerve Injury. Wrist drop due to extensor muscles paralysis Finger drop due to extensor digitorum paralysis Loss of sensation in fingers on dorsum of hand Elbow extension is done by triceps supplied from radial nerve trunk in axilla & also in radial groove. High Radial nerve Injury Very high radial nerve palsy Low radial nerve palsy Aetiology shaft or humerus Prolonged application of tourniquet Pressure on arm as in Saturday night paralysis Injections From excessive callus formation of old fracture impinging on the nerve C/F- Elbow extension spared Lost: Wrist, thumb and finger extension; sensation over 1st web space Aetiology Crutch palsy Aneursysm of axillary vessels C/F - Total palsy Aetiology Dislocation of elbow neck of radius Enlarged bursae Rheumatoid synovitis of elbow During operation for excision of radius head C/F- Elbow extension spared with weak wrist extension and radial detion Lost-thumb, finger extension: sensory over dorsum of 1st web space *Crutch palsy patient pushes crutches into the axilla & compresses the radial nerve in axilla triceps will be paralysed resulting in loss of extension it is very high radial nerve injury. *Posterior interosseous nerve injury sensory loss will not be there because it is pure motor nerve. [/INST] question: A 26 years male person has got injury to mid-arm. Patient developed wrist drop, finger drop and loss of sensation on dorsum of hand. Patient is able to do elbow extension. The diagnosis is | options: A: Very high radial nerve injury B: High radial nerve injury C: Low radial nerve injury D: Posterior interosseus nerve injury | answer: B </s>