1. A neck dissection is a surgical procedure to remove lymph nodes and surrounding tissue in the neck to treat cancer that has spread from areas like the oral cavity or larynx. 2. There are different types of neck dissections classified based on the extent of lymph nodes and structures removed, including radical, modified radical, and selective neck dissections. 3. The specific type of neck dissection performed depends on factors like the location and stage of the cancer, and whether preservation of structures like the spinal accessory nerve or internal jugular vein is needed.