Breast Anatomy

DEVELOPMENT:

• Tanner I:No glandular tissue: areola follows the skin contours of the chest (prepubertal) (typically age 10 and younger)
• Tanner II: Breast bud forms, with small area of surrounding glandular tissue; areola begins to widen (10–11.5)
• Tanner III: Breast begins to become more elevated, and extends beyond the borders of the areola, which continues to widen but remains in contour with surrounding breast (11.5–13)
• Tanner IV :Increased breast size and elevation; areola and papilla form a secondary mound projecting from the contour of the surrounding breast (13–15)
• Tanner V: Breast reaches final adult size; areola returns to contour of the surrounding breast, with a projecting central papilla. (15+)

ANATOMY:

The breast can be considered to be composed of two regions:

• Circular body – largest and most prominent part of the breast.
• Axillary tail – smaller part, runs along the inferior lateral edge of the pectoralis major towards the axillary fossa.

MICROANATOMY:

• The breast is composed of mammary glands surrounded by a connective tissue stroma.

Mammary Glands

• Modified sweat glands. They consist of a series of ducts and secretory lobules (15-20).
• Each lobule consists of many alveoli drained by a single lactiferous duct. 
• These ducts converge at the nipple like spokes of a wheel.

Connective Tissue Stroma

• Fibrous and a fatty component.
• The fibrous stroma condenses to form suspensory ligaments (of Cooper). These ligaments have two main functions:
• Attach and secure the breast to the dermis and underlying pectoral fascia.
• Separate the secretory lobules of the breast.

Pectoral Fascia

• The base of the breast lies on the pectoral fascia – a flat sheet of connective tissue associated with the pectoralis major muscle.
•  It acts as an attachment point for the suspensory ligaments.
• There is a layer of loose connective tissue between the breast and pectoral fascia – known as the retromammary space. 
• This is a potential space, often used in reconstructive plastic surgery.

BLOOD AND NERVE SUPPLY:

• Each breast receives blood supply from lateral thoracic branches of axillary artery and intercostal arteries.
• The veins accompany the arteries.
• The lymphatics drain into axillary, transpectoral and internal mammary nodes, hence the need to remove them in breast cancer.
• The nerves come from fourth, fifth and sixth intercostal nerves