What are the causes of swollen lymphnodes in the jaw and neck area in children?

Infection. Swollen lymph nodes are usually a result of an infection. The lymph nodes swell because they are part of the immune systems attempt to fight off an infection. Different lymph nodes protect different parts of the body. If a swollen node persists, is red or very tender, or if it keeps getting bigger, have your child checked by your pediatrician.
Lots of things. Must see both dentist and physician to determine source of infection that is affecting lymph nodes.