<prompt> A 30-year-Old male underwent excision of the right radial head. Following surgery, the patient developed an inability to extend the fingers and thumb of the right hand. He did not have any sensory deficit. Which one of the following is the most likely cause?Injury to Posterior interosseus nervelatrogenic injury to common extensor originInjury to anterior interosseus nerveHigh radial nerve palsy  <response>: Clinical features of radial nerve palsy Clinical features depend upon the site of the lesion.1 1f lesion is highWrist drop, thumb drop and finger drop.Inability to extend elbow, wrist, thumb fingers MP jointThe patient can extend interphalangeal joints due to the action of lubricants and interossei.Sensory loss over posterior surface of arm forearm and lower lateral half of forearm.2 If the lesion is lowa Type IWrist drop, thumb drop and finger drop.Elbow extension is preserved.Sensory loss over the dorsum of first web space.b Type IIThumb drop and finger dropElbow and wrist extension is preservedSensory loss over the dorsum of first web spaceClinical features of posterior interosseous nerveIt is prone to be injured in injury operations of radial head- neck.There is no sensory deficit as it is a pure motor nerve.Wrist extension is preserved i.e. no wrist drop due to spared extensor carpi radialis longus .Presents with loss of extension of metacarpophalangeal MP joints i.e., thumb finger drop. 