The lymphatic system is a complex network of thin vessels, valves, ducts, nodes, and organs. It helps to protect and maintain the fluid environment of the body by producing, filtering, and conveying lymph and by producing various blood cells.
The lymph system is present throughout the body. Common areas where the lymph nodes can be felt (palpable nodes) include:
- the groin area (inguinal region)
- armpit (axilla)
- the neck (there is a chain of lymph nodes on either side of the front of the neck, both sides of the neck, and down each side of the back of the neck)
- under the jaw and chin
- behind the ears
- over the prominence on the back of the head (occiput)
Lymph nodes play an important part in the body's defense against infection. Swelling might occur even if the infection is trivial or not apparent. Swelling of lymph nodes generally results from localized or systemic infection, abscess formation, or malignancy. Other causes of enlarged lymph nodes are extremely rare. By far, the most common cause of lymph node enlargement is infection.
As a rule, when swelling appears suddenly and is painful, it is usually caused by injury or an infection. Enlargement that comes on gradually and painlessly may result from malignancy or tumor.
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