Lymphadenopathy is a term implying an abnormal or diseased state of the lymph nodes.
The supraclavicular lymph nodes are located above the clavicles in the supraclavicular fossa. They drain intrathoracic structures including the lungs and part of the gastric region. The left supraclavicular lymph nodes drain the left lungs and the lower lobe of the right lung. The right supraclavicular lymph nodes drain the upper lobe of the right lung and the stomach. Therefore pathologies like cancer and infections will at some stage infiltrate the nodes of their respective sides.
You can palpate the supraclavicular lymph nodes by standing in front of or behind the patient. Use the fingertips of your index and middle fingers and try to feel the tissues along the superior and deep borders of the clavicles. Then ask the patient to shrug their shoulders to improve access to the supraclavicular fossae and palpate them again.
(Full details and demonstration of procedures are provided with the DVD/videos and associated study material)