This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Triangles of Neck, Subject name: Anatomy
[{'content': 'All the following structures are related to carotid sheath except: \nSelect and explain. \nA. Sympathetic trunk, B. Vagus nerve, C. Internal carotid artery, D. Internal jugular vein', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans: A (Sympathetic trunk) Ref: Grays Anatomy 40th EdExplanation:Carotid sheathIt is the tubular investment of deep cervical facsiaThe anterior wall of the sheath is formed by pre-traeheal fasciaThe posterior wall is formed by pre-vertebral fasciaAnca cervicalis embedded in the anterior wall of carotid sheathContents:1. Common carotid artery2. Internal carotid artery3. Internal jugular vein4. Vagus nerve', 'role': 'assistant'}]