Lymph nodes are oval-shaped organ of lymphatic system, distributed throughout the body. It is linked by lymphatic vessels. It stores inter alia, B and T lymphocytes, and macrophages. It acts as filters/traps for foreign particles.

Lymphadenopathy is pathology of lymph node.

Humans have 500-600 lymph nodes distributed throughout the body, w/ clusters found in the neck, chest, underarms, abdomen, and groin.

• Lymph nodes of the head, including:
  • Occipital lymph nodes
  • Mastoid lymph nodes
  • Parotid lymph nodes
• Lymph nodes of the neck, including:
  • Cervical lymph nodes:
    • Submental lymph nodes
    • Submandibular lymph nodes
  • Deep cervical lymph nodes:
    • Deep anterior cervical lymph nodes
    • Deep lateral cervical lymph nodes
  • Inferior deep cervical lymph nodes:
    • Jugulo-omohyoid lymph node
    • Jugulodigastric lymph node
  • Supraclavicular lymph nodes:
    • Virchow's nodes
• Lymph nodes of the thorax, including:
  • Lymph nodes of the lungs
  • Mediastinal lymph nodes
• Lymph nodes of the arm, including:
  • Superficial lymph nodes of the arm:
    • Supratrochlear nodes
    • Deltoideopectoral nodes
  • Deep lymph nodes of the arm:
    • Lateral nodes
    • Anterior or pectoral nodes
    • Posterior or subscapular nodes
    • Central or intermediate nodes
    • Medial or subclavicular nodes
• Lymph nodes of the lower limbs, including:
  • Superficial inguinal lymph nodes
  • Deep inguinal lymph nodes
  • Popliteal lymph nodes

Source: http://www.organsofthebody.com/images/lymph-nodes.jpg