This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head and neck, Subject name: Anatomy
[{'content': 'Structures preserved in functional radical dissection of the neck -a) Int. jugular veinb) Sternomastoidc) Lymph nodesd) Accessory nerve \nSelect and explain. \nA. abc, B. bcd, C. abd, D. acd', 'role': 'user'}, {'content': "Answer: C \nExplanation: Functional dissection is modified radical neck dissection (MRND Type III ) Modified radical neck dissection is done only selected cases where tumor is very well differentiated and less aggressive like in papillary carcinoma of thyroid with lymph node secondaries . Structures preserved here are sternomastoid muscle , internal jugular vein and spinal accessory nerve . Ref - Srb's manual of surgery 5/e p450", 'role': 'assistant'}]