A 6 week old boy is brought to the Paediatrician in Kanpur. His parents repo that he has not had significant use of his right arm since bih. Bih history is significant for a prolonged labor with difficult breech delivery. On physical examination, his arm hangs at his side and is in a medially rotated position with the forearm in pronation. He will actively use his left arm, but does not move his affected right arm or hand. Injury to which of the following cervical nerve roots account for this patient's posture?
High-Yield Explanation
This patient has an Erb-Duchenne palsy, which is the result of an injury to the superior trunks of the C5 and C6 nerve roots.The C8 and T1 nerve roots are injured in a Klumpke's paralysis.The other combinations all may be injured as a result of bih palsy, but do not have distinct syndromes associated with them.