The neck has an extensive lymphtic network containing more than 1/3  of the body's total number. Typically as many as 75 lymph nodes are located in each side of the neck. Lymph nodes are clustered in regions throughout  the vessels of the lymphatic system. The lymph vessels  carry fluid from the interstitial spaces to the lymph nodes  so it can be filtered , before being emptied  into the venous blood  supply. In the cervical region , nodes are  grouped along the lower border of the jaw, in front and behind the ears ,deep in the neck along the larger blood vessels . They drain the scalp, face , tissues of the nasal cavity, pharynx, trachea, upper esophogus, thyroid and salivary glands. the lymph nodes of the neck can be  classified into 6 levels for ease of Identification; both clinically and surgically.