LYMPHATIC DRAINAGE OF MAMMARY GLAND

• Lymphatic system is the body's secondary circulatory system
• Lymphatic system resembles veins in structure
• Lymphatic system is elastic in nature and has valves to prevent backflow
• Lymph nodes are present along the length of the lymphatic system
• Lymph nodes contain a yellow fluid called lymph that flows through the lymphatic system
• Axillary lymph nodes are located in the axilla and are arranged in five groups:

  • Anterior group nodes: about 4 to 5 nodes located deep to pectoralis major and lower border of pectoralis minor
  • Lateral group nodes: about 4-6 nodes located along axillary vein
  • Posterior group nodes: about 6-7 nodes located along subscapular vessels
  • Central group nodes: about 3 or 4 nodes located in the axillary fats
  • Apical group nodes: about 6-12 larger nodes located along the apex of the axilla, above the pectoralis minor and along the medial side of the axillary vein
• Internal mammary/Parasternal nodes are located along the internal thoracic vessels (lateral to the sternal bone)
• Posterior intercostal nodes are located in the posterior part of the intercostal space
• Other nodes include Supraclavicular nodes and Delto-pectoral nodes
• Superficial lymphatic vessels drain lymph from the skin overlying the mammary gland except the nipple and areola
• Skin of the medial part of the mammary gland drains into the parasternal/internal mammary of the same side, but few lymphatics can cross to the opposite side
• Skin of the rest of the mammary gland drains into the anterior group of axillary lymph nodes
• Deep lymphatic vessels:

  • Upper lateral quadrant lymph drains into axillary lymph nodes (anterior group, posterior group, central group, apical group)
  • Lower lateral quadrant lymph also reaches the posterior intercostal group of lymph nodes
  • Upper medial quadrant lymph reaches Internal mammary/Parasternal nodes of the same side and some to the opposite side
  • Lower medial quadrant lymph communicates with the subdiaphragmatic and subperiosteal lymph plexus which leads to the abdomen
  • Upper quadrant lymph drains directly into apical and supraclavicular lymph nodes
• 75% of the lymph drains into axillary lymph nodes, 20% drains into internal mammary (parasternal) lymph nodes, and 5% drains into posterior intercostal lymph nodes
• Lymph vessels of the breast communicate with the abdomen, allowing cancer of the breast to spread to the liver
• The upper, outer quadrant of the breast contains large numbers of glandular tissue and is the site of 60% of breast carcinomas
• Infiltration of the ligament of cooper by breast cancer cells can lead to its shortening, giving it a Peau de Orange appearance of the breast
• Lactiferous ducts are radially arranged from the nipple, so incision of the gland should be made in a radial direction to avoid cutting through the duct