This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Orthopaedics
[{'content': 'Only finger drop and no wrist drop in Posterior interosseus nerve injury, is due to sparing of \nSelect and explain. \nA. Triceps, B. Brachioradialis, C. Anconeus, D. Extensor carpi radialis longus', 'role': 'user'}, {'content': 'Answer: D \nExplanation: (D) Extensor carpi radialis longus> Posterior interosseous neuropathy is purely a motor syndrome resulting in finger drop, and radial wrist deviation on extension.# LESIONS OF RADIAL NERVE:> All branches below the injured region will be interrupted.1. Axilla (Very high):> Causes: Glenohumeral dislocation, Fracture proximal humerus, Crutch palsy> Deficit: Total palsy# Triceps weakness: Tested by resisted active extension of elbow and feeling for muscle contraction# Brachioradialis: Tested by resisted active flexion of elbow with forearm in midprone position and feeling for muscle contraction# Wrsit drop: Due to paralysis of wrist extensors- Ask to grasp something, the wrist becomes flexed if extensors are weak# Finger drop: Due to paralysis of long finger extensors causing inability to extend fingers at MCPJ# Thumb drop: Due to paralysis of extensor pollicis longus and abductor pollicis longus- Extensor pollicis longus is examined by stabilizing the MCPJ of thumb and resisted active extension of IP joint of thumb# Sensory loss: Over autonomous zone (1st dorsal webspace)2. Radial groove (High):- Cause: Fracture shaft of humerus, Saturday night palsy, Injection, Callus, Torniquet- Deficit: Brachioradialis weakness, Wrist drop, Finger drop, Thumb drop, Sensory loss3. Below Elbow (Low):- Causes: Fracture of radial head, Posterior dislocation of radius at elbow joint- Deficit: Posterior Interosseous Nerve# No wrist drop (Sparing of Extensor carpi radialis longus which enables extension of wrist)# Finger drop, Thumb drop# No Sensory loss', 'role': 'assistant'}]