<prompt> Structures preserved in functional neck dissection isCarotid aery, Vagus nerveSternomastoid muscle, Internal Jugular veinSpinal accessory nerve, Submandibular salivary glandNeck nodes  <response>: Ans. is b i.e., Sternocleidomastoid muscle and Internal jugular vein 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- Schwaz Classical Radical neck dissection It involves the removal of following structures i Cervical lymphatics and lymph nodes ii Internal jugular vein iii Accessory nerve iv Submandibular gland v Sternomastoid muscle The main disability that follows operation is the drooping of the shoulder due to paralysis of the Trapezius muscle as a consequence of excision of accesory nerve. Modified Radical Neck dissection Functional neck dissection -- In this operation all the lymphatics and lymph nodes are removed as in radical neck dissection. The difference is that one or more of the following structures are preserved. i Accessory nerve ii Sternocleidomastoid muscle iii Internal jugular vein 