Just like the cardiovascular system, the lymphatic system stems throughout the entire body. Composed of organs, ducts, vessels and nodes, the main function of the system is to transport lymph fluid from body tissues into the bloodstream. Lymph fluid flows through the lymphatic vessels and into the lymph nodes -- small, bean-shaped structures clustered throughout the system. These nodes produce immune cells, filter lymph fluid and remove foreign substances, such as bacteria and cancerous cells. Located near the back of the head, occipital nodes might swell with an infection or disease -- but usually not with allergies, according to "Physical Examination & Health Assessment," by Carolyn Jarvis.
Small clusters of lymph nodes are scattered throughout the human body. A large number of the nodes are located in the head and neck. Several clusters of nodes run along the front and back of the neck -- both above and below the muscles. Lymph nodes can also be found just underneath the jaw bone, below the chin and just above the collar bone. Lymph nodes also reside in the arms, under the armpits, near the groin, underneath the hips, and deep in the center of the abdomen and chest.
Each cluster of nodes in the head and neck has a specific name -- which is often based on the cluster’s location. The occipital lymph nodes are found near the back of the head, just at the base of the skull where the head and neck come together. This lymph node cluster receives its name from the lower skull bone -- the occipital bone. These nodes collect lymph fluid that has passed around the scalp. Like all other nodes, they filter the lymph fluid and remove foreign substances.
Reasons for Swelling
Typically, normal lymph nodes cannot be felt by pressing on the skin. But when the nodes swell, they can be felt by your fingers quite easily. Swollen lymph nodes are often the size of a pea or bean -- and they might be tender or painful. Lymph nodes most commonly swell as a result of infection. In the case of occipital nodes, the swelling typically occurs with a bacterial, viral or fungal infection of the scalp. Occipital node swelling might also occur with ringworm infection, dandruff or lice infestation. In some cases, an infection of the ears or throat could also cause lymph node swelling. Rarely, the occipital nodes swell in response to cancerous cells in other parts of the body. In this case, you will likely have additional symptoms or notice lymph node swelling in several areas.
Depending on the specific allergy, your body’s physical response might include lymph node swelling. When the body is hypersensitive to a particular trigger -- whether it’s hay fever, cat hair or peanuts -- it launches an immune response upon coming into contact with the substance. Since the lymph system is involved so heavily in the immune response, lymph node reactions are possible.
While swollen lymph nodes often return to normal size without any medical treatment, there are a few specific cases in which you should consult your physician. To be safe, call your doctor any time you notice a swollen lymph node that continues to enlarge or remains swollen for two weeks or longer. You’ll also want to consult your doctor if the node feels solid and hard and does not move when you push on it.