<prompt> Structures preserved in functional neck dissection is -Carotid artery, Vagus nerveSternomastoid muscle, Internal Jugular veinSpinal accessory nerve, Submandibular salivary glandNeck nodes  <response>: 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- SchwartzClassical Radical neck dissection It involves the removal of following structuresCervical lymphatics and lymph nodesInternal jugular veinAccessory nerveSubmandibular glandSternomastoid muscleThe 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.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.Accessory nerveStemocleidomastoid muscleInternal jugular vein 