This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nerve supply, Nerve Lesions, Subject name: Anatomy
[{'content': 'A 29-year-old man comes in with a stab wound, cannot raise his arm above horizontal, and exhibits a condition known as "winged scapula." Which of the following structures of the brachial plexus would most likely be damaged? \nSelect and explain. \nA. Medial cord, B. Posterior cord, C. Lower trunk, D. Roots', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Winged scapula is caused by paralysis of the serratus anterior muscle that results from damage to the long thoracic nerve, which arises from the roots of the brachial plexus (C5-C7)', 'role': 'assistant'}]