What Are the Axillary Nodes?

The axillary nodes, sometimes also referred to as the axillary lymph nodes, are bean-shaped glands that play an important role in the lymphatic system in humans and certain animals. They’re typically located in the armpit area, and are usually bunched together in branched clusters. Circulating lymph fluid is their primary responsibility; they filter and pump it from the upper chest region to other nodes and glands in the system. Lymph fluid is a yellowish-colored, nutrient-rich liquid that plays a major role in immunity; it is dense in white blood cells and helps the body fight infection and disease. When cancerous cells penetrate the lymphatic tissues, though, they are often able to grow and disperse very quickly. The axillary lymph nodes are often heavily impacted in the development of breast cancer. People who are considered to be at risk for breast and other related cancers are usually advised to have these nodes regularly checked and biopsied to monitor for cancerous and pre-cancerous growth.

The human lymphatic system is a complex network of nodules, nodes, and vessels that continuously circulate fluid around the body. It works a lot like the blood circulatory system and its main role is usually to clean up any leaks or debris left in the wake of blood flowing through the veins.

Lymph fluid contains a dense concentration of white blood cells, called lymphocytes, that fight infection by destroying bacteria and foreign particles. While in the lymph nodes, the lymphocytes work to filter the toxins out of the bloodstream. Once the lymph fluid is filtered, it can safely be recirculated back into the blood stream without these toxins entering the blood stream and causing infection.

Each node in the lymphatic system contains vessels that work to carry the lymph fluid into and out of the node, and those in the axillary system are no different. Unfiltered lymph fluid is carried into the nodes by afferent vessels. Once the fluid has been filtered, it is returned to the circulatory system by what’s known as the efferent vessels.

The 20 to 30 axillary nodes in this system range from a few hundredths of an inch (a few millimeters) to 0.39 to 0.78 inch (1 to 2 cm) at their normal size. They are found in five groups: the lateral or brachial lymph nodes, the anterior or pectoral lymph nodes, the posterior or subscapular lymph nodes, the central lymph nodes, and the medial or subclavicular lymph nodes.

The brachial nodes contain four to six glands, and serve to drain most of the arm, with the exception of the part that receives circulation from the cephalic vein. The pectoral nodes contain four to five glands, which drain the front and side thoracic walls along with part of the breasts. The subscapular nodes contain six or seven glands, and drain the skin and muscles of the lower back and neck and also the back thoracic wall. The central nodes are a group of three or four nodes that drain fluid received from the lateral, anterior, and posterior groups, while the subclavicular nodes drain fluid received from all the other nodes and sometimes the breast.

The axillary nodes often play a large role in breast cancer. Breast tumors can release cancer cells into the lymphatic system, which can become trapped in the nearby axillary nodes. If cancer cells are present in the lymph nodes, the likelihood of metastic breast cancer rises.

Doctors and other medical professionals who are concerned about the presence of cancer cells in these nodes often perform an axillary lymph node dissection (ALND), often during a mastectomy or lumpectomy. The surgeon will remove some or all of the nodes, which are then sent to a laboratory where they are screened for cancer cells. If the results come back negative, they are free of cancer cells. If the results come back positive, however, they contain the cells. This diagnosis is important because it plays a part in determining the stage of the breast cancer and further treatment options.

There’s not usually much anyone can do to prevent breast cancer or other problems with the lymphatic nodes. Regular monitoring and preventative care can help catch problems early, though, which can dramatically impact the success rates of different treatment plans.