Neck dissection is a surgical procedure that removes lymph node-bearing tissue in the neck, either because it contains known metastases or is at high risk of containing yet-undetected (i.e., microscopic) metastases. Neck dissection is often combined with removal of the primary tumor. The original neck dissection, today called a radical neck dissection, removes fat and lymph nodes, the jugular vein, and sternocleidomastoid muscle. Later types of neck dissections were devised to reduce the morbidity of this surgery without compromising effectiveness. The commonest variants today are called selective neck dissections; these remove removes fat and lymph nodes from targeted parts of the neck most likely to be involved with metastasis, and tend to spare muscles of the neck, the jugular vein, and cranial nerve 11.