Anatomy of the Breast

Breast quadrants. From Bates B: A guide to physical examination and history taking, ed 6, Philadelphia, 1995, Lippincott-Raven. The female breast is suspended from the chest wall between the 2nd and 6th ribs. The breast is bounded medially by the lateral edge of the sternum and extends laterally to the anterior axillary line. Breast tissue can be divided into four quadrants and is roughly circular except at the upper outer quadrant where the tail of Spence extends into the axilla. The breast is composed of three types of tissue: Three types of breast tissue. From Bates B: A guide to physical examination and history taking, ed 6, Philadelphia, 1995, Lippincott-Raven. Glandular tissue Fibrous tissue Fat Glandular tissue produces milk and is made up of lobes arranged radially around the nipple that each drain into a duct. Each duct onto the nipple surface. This glandular tissue is supported by fibrous tissue that tethers the breast to the skin and to the underlying fascia. Fatty tissue surrounds the breast. The proportion of fat present in breast tissue varies by age, pregnancy, and other factors. The nipple—areola complex contains smooth muscle fibers arranged longitudinally and circularly in the nipple and in concentric rings in the areola. These smooth muscle fibers function to contract the areola and compress the nipple, thereby emptying the milk ducts.   Lymphatic network. From Bates B: A guide to physical examination and history taking, ed 6, Philadelphia, 1995, Lippincott-Raven.   Lymphatic drainage of the breast. From Swartz MH: Textbook of physical diagnosis: history and examination., ed 3, Philadelphia, 1998, Saunders.   A rich lymphatic network of vessels in the breast drains mainly into the axillary and internal mammary lymph nodes. The axillary nodes are the more numerous. The central nodes deep within the axilla are the most often palpable. There are also pectoral, subscapular, and lateral axillary nodes that are usually not palpable. Lymph from the lower outer quadrant drains to the lateral and inferior axillary nodes, while lymph from the areola, upper outer quadrants, and tail drains into the lymph nodes in the superior part of the axilla. Most of the lymph from the inner quadrants drains into the internal mammary lymph nodes even though these are much fewer in number.