Lymphatic Drainage of the Breast

Distribution of Lymphatics in the Breast

The mammary glands and surrounding tissues of the breast are drained by two sets of lymphatic vessels. There are lymphatics that originate in and drain the surface area and skin over the breast (excluding the areola and nipple areas). There are also lymphatics that originate in and drain the underlying tissue of the breast itself (including the skin of the areola and nipple).

FIGURE 19-5 Structure of a lymph node. A, A lymph node is typically a small structure into which afferent lymphatic ducts empty their lymph. Efferent lymphatic ducts drain the lymph from the node. An outer fibrous capsule maintains the structural integrity of the node. B, Photograph of a dissected cadaver shows a lymph node and its associated lymphatic vessels, along with nearby muscles, nerves, and blood vessels. C, Internal structure of a lymph node. Several afferent valved lymphatics bring lymph to the node. In this example, a single efferent lymphatic leaves the node at a concave area called the hilum. Note that the artery and vein also enter and leave at the hilum. Arrows show direction of lymph movement.

FIGURE 19-6 Lymphatic drainage of the breast. Note the extensive network of lymphatic vessels and nodes that receive lymph from the breast. Surgical procedures called mastectomies, in which some or all of the breast tissues are removed, are sometimes performed to treat breast cancer. Because cancer cells can spread so easily through the extensive network of lymphatic vessels associated with the breast, the lymphatic vessels and their nodes are sometimes also removed. Occasionally, such procedures cause swelling, or lymphedema.

More than 85% of the lymph from the breast enters the lymph nodes of the axillary region (Figure 19-6). Most of the remainder enters lymph nodes along the lateral edges of the sternum. Several very large nodes in the axillary region physically contact extensions of breast tissue.