This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'Structures preserved in functional neck dissection is - \nSelect and explain. \nA. Carotid artery, Vagus nerve, B. Sternomastoid muscle, Internal Jugular vein, C. Spinal accessory nerve, Submandibular salivary gland, D. Neck nodes', 'role': 'user'}, {'content': 'Answer: B \nExplanation: "In contrast to a radical neck dissection, the internal jugular vein, the spinal accessory nerve, the cervical sensory nerves, and the sternocleidomastoid muscle are preserved unless they are adherent to or invaded by tumor"- Schwartz\nClassical Radical neck dissection \xa0→ It involves the removal of following structures\n\n\nCervical lymphatics and lymph nodes\n\n\nInternal jugular vein\n\n\nAccessory nerve\n\n\nSubmandibular gland\n\n\nSternomastoid muscle\n\n\n\nThe main disability that follows operation is the dropping of the shoulder due to paralysis of the Trapezius muscle as a consequence of excision of accessory nerve.\n\nModified Radical Neck dissection (Functional neck dissection) \xa0→ In this operation all the lymphatics and lymph nodes are removed as in radical neck dissection.\nThe difference is that one or more of the following structures are preserved.\n\n\n\nAccessory nerve\n\n\nStemocleidomastoid muscle\n\n\nInternal jugular vein', 'role': 'assistant'}]