CLASSIFICATION, LOCATION AND AREAS DRAINED BY THE AXILLARY LYMPH NODES

• Anterior (pectoral) group lies along lateral thoracic vessels, receives lymph from upper half of anterior wall of the trunk and from major portion of the breast.

• Posterior (scapular) group lies along the subscapular vessels, on the posterior fold of the axilla, receives lymph from the posterior wall of the upper half of the trunk and from the axillary tail (an extension of the tissue of the breast that extends into the axilla) of the breast.

• Lateral (brachial or humeral) group lies along the upper part of the humerus bone (of arm), medial and posterior to the axillary vein, receives lymph from the upper limb (arm)

• Central (intermediate)  group lies in the fat of the axilla (near its base) and is closely related to the intercostobrachial nerve, receives lymph from the other axillary lymph node groups and the floor of axilla.

• Apical (infraclavicular) group lies partly posterior to the upper portion of the pectoralis minor and partly above the upper border of this muscle, along the axillary vessels, receives lymph from the upper part of the breast, the thumb and its web and from the central group also.

COURSE OF DRAINAGE

In the underarm region, they receive lymph from vessels that drain the arm, the walls of trunk, the breast and upper walls of the abdomen. Eventually all the groups drain finally into the apical group from where efferent join to form the subclavian trunk, which opens into the jugular lymphatic trunk or directly into the junction of the internal jugular and subclavian veins. A few efferent from the apical group usually pass to the inferior deep cervical nodes.

SOME IMPORTANT CLINICAL ASPECTS

A lump in the armpit can be felt, the reason being the enlarged lymph nodes which can be due to injury, inflammation, infection, AIDS or tumor etc.

Major drainage of the breast is in the axillary lymph nodes due to which the cancer of the breast in females can spread through these lymph nodes to other parts of body by the lymphatic system so they help in its spread (metastasis). They are important in making diagnosis of breast cancer and are examined. In case of surgery when the breast is removed, they are also removed with the tumor to avoid any spread of the cancer.