This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Peripheral nerve injuries, Subject name: Orthopaedics
Muscles paralysed in Erb's paralysis are all except - 
Select and explain. 
A. Biceps, B. Triceps, C. Brachioradialis, D. Brachialis
B: Triceps
Answer: B: Triceps 
Explanation: Erb&; s palsy is due to injury to the C5 nerve root & rarely the C6 nerve root is injured . * Effects of injury - at shoulder : paralysis of deltoid , rhomboids , supra & infraspinatus & teres minor muscles . This results in loss of shoulder abduction & external rotation . - at elbow : biceps & brachialis muscles are paralyzed . This results in loss of flexion of elbow joint. - at forearm : supinator muscle paralyzed resulting in loss of supination of forearm - combined effect of injury is an arm hanging loose by the side of the trunk . The shoulder is internally rotated , the elbow is in extension , forearm is pronated & wrist is in flexion . This characteristic posture is popularly known as policeman or waiter &;s tip. - apa from this , there may sensory loss on outer aspects of the forearm both in front & back. REF:textbook of ohopedics, John Ebenezer,4th edition,pg.no.350