Anatomy of Mammary Gland (Animated video)

#breastanatomy #mammarygland #pectoralregion #grossanatomy
The knowledge of lymphatic drainage of the breast is of great clinical importance due to high percentage of occurrence of cancer in the breast and its subsequent spreading of cancer cells (metastasis) along the lymph vessels to the regional lymph nodes.
Lymph nodes of mammary gland
1. Axillary lymph nodes are chief lymph nodes of breast and further divided inti 4 groups
• Anterior/pectoral
• Posterior/subscapular
• Central
• Lateral/humeral
• Apical
2. Internal mammary nodes, present along internal thoracic vessels
3. Supraclavicular nodes and infraclavicular nodes are present above and below the clavicle respectively.
4. Posterior intercostal nodes lie in the posterior part of the intercostal space in front of head of ribs.
5. Cephalic/deltopectoral nodes, present in deltopectoral groove.
6. Subdiaphragmatic nodes
7. Subperitoneal nodes
The lymphatics draining the breast are divided into two groups: (a) superficial and (b) deep.
 Superficial lymphatics drain the skin of the breast except that of nipple and areola.
 Deep lymphatics drain the parenchyma of the breast, and skin of the nipple and areola.
• A plexus of lymph vessels deep to the areola is called subareolar plexus of Sappey.
• The subareolar plexus and most of the lymph from the breast drain into the anterior group of axillary lymph nodes.

The superficial lymphatics of the breast of one side communicate with those of the opposite side. Consequently, the unilateral malignancy may become bilateral.

The lymphatic drainage from the mammary gland occurs as follows
 It is divided into four (upper and lower; lateral and medial) quadrants.
 The lymph from lateral quadrants of the breast is drained into anterior axillary or pectoral group of lymph nodes. These lymph nodes are situated deep to the lower border of pectoralis minor.
 The lymph from medial quadrants is drained into internal mammary lymph nodes situated along the internal mammary artery. Some lymphatics may go to the internal mammary lymph nodes of the opposite side.
 A few lymph vessels from the lower lateral quadrant of the breast follow the posterior intercostal arteries and drain into posterior intercostal nodes located along the course of these arteries.
 The few lymph vessels from the lower medial quadrant of the breast pierce the anterior abdominal wall and communicate with subdiaphragmatic and sub-peritoneal lymph plexuses.
 The lymph vessels from the deep surface of the breast pierce pectoralis major and clavipectoral fascia to drain into the apical group of axillary lymph nodes.
Important points
• 75% of lymph into axillary nodes: Mostly received by anterior group and partly by posterior group to lateral and central group, finally to apical group to supraclavicular nodes
• 20 % into internal mammary nodes
• 5% into posterior intercostal lymph nodes
• Among the axillary lymph nodes, most of the lymph drains into the anterior axillary nodes and the remaining into posterior and apical groups. The lymph from anterior and posterior groups first goes to the central and lateral groups, and then through them into the supraclavicular lymph nodes.
• Sentinel node is the first lymph node or a group of lymph nodes to which cancer cells are likely to spread from the primary tumor.
Nerve supply
• Anterior and lateral branches of 4th to 6th intercostal nerves

Applied anatomy
 Breast cancer (carcinoma of the breast): It is one of the most common cancers in the females. It arises from the epithelial cells of the lactiferous ducts.
• In about 60% cases, it occurs in the upper lateral quadrant and commonly affects females between 40–60 years of age.
• Clinically it presents as:
 Presence of a painless hard lump.
 Breast becomes fixed and immobile, due to infiltration of suspensory ligaments.
 Retraction of skin, due to infiltration of suspensory ligaments.
 Retraction of nipple due to infiltration and fibrosis of lactiferous ducts.
• Cancer cells may infiltrate the suspensory ligament and breast becomes fixed, contraction of the ligament produces retraction of skin
• Peau d’ orange syndrome: Obstruction of superficial lymphatics may produce oedema of the skin giving rise to an appearance of a skin of orange.
• On rare occasions, cancer cells from sub peritoneal plexuses undergo transcoelomic migration and produces secondary deposit on ovary forming Krukenburg ‘s tumour.
• Radical mastectomy: Removal of complete breast along with axillary lymph nodes, and pectoralis major and minor muscles
• During surgery of mammary gland radial incisions should be put to avoid damaging the lactiferous ducts.

 Amastia: Bilateral agenesis of mammary gland.

 Polythelia: Supernumerary nipples.

 Gynaecomastia: Development of breast in males in Klinefelter’s syndrome (47XXY).