Lymph nodes are body organs (not glands) spread throughout your body. Their function is to filter out all the dead bacteria, viruses, and other dead tissue from the lymphatic fluid and eliminate it from the body. They are also the place where the white blood cells (lymphocytes) spend much of their time. When the immune system is activated they begin producing large numbers of lymphocytes which causes them to swell.
There are about 500-700 lymph nodes spread throughout the body. Click on the diagrams below for highly detailed pictures of where the lymph nodes are located. Below the pictures you will find information about the proper size that lymph nodes should be, their names, and a quick summary of how they feel and what it means.
Lymphadenopathy and Malignancy from the American Academy of Family Physicians
Lymphadenopathy: Differential Diagnosis and Evaluation
Some of the common names of the lymph node locations you will encounter are :
Most normal lymph nodes are about 1cm in size (0.5 to 2.0cm) but that size varies depending on the location of the node, and what activity is going on. Infections, cancer and many other conditions can cause it to expand as the immune system reacts to the problem.
Abnormal size is defined as:
Note: Epitrochlear in layman's terms means near the elbow or funny bone
From the links about lymphadenopathy at the top of this page you will also learn that the texture of the nodes is important. For example: