Breasts

The breasts consist of mammary glands and associated skin and connective tissues. The mammary glands are modified sweat glands in the superficial fascia anterior to the pectoral muscles and the anterior thoracic wall. The breasts extend horizontally from the region of the lateral border of the sternum to the midaxillary line, and vertically from ribs 2 to 6.

The mammary glands consist of a series of ducts and associated secretory lobules. These converge to form 15 to 20 lactiferous ducts, which open independently onto the nipple. The nipple is surrounded by a circular pigmented area of skin termed the areola.

A well-developed, connective tissue stroma surrounds the ducts and lobules of the mammary gland. In certain regions, this condenses to form well-defined ligaments, the suspensory ligaments of breast, which are continuous with the dermis of the skin and support the breast.

In nonlactating women, the predominant component of the breasts is fat, while glandular tissue is more abundant in lactating women.

The breast lies on deep fascia related to the pectoralis major muscle and other surrounding muscles. A layer of loose connective tissue (the retromammary space) separates the breast from the deep fascia and provides some degree of movement over underlying structures.

Arterial Supply

The breast is related to the thoracic wall and to structures associated with the upper limb; therefore, vascular supply and drainage can occur by multiple routes:

  • laterally, vessels from the axillary artery - superior thoracic, thoraco-acromial, lateral thoracic, and subscapular arteries

  • medially, branches from the internal thoracic artery;

  • the second to fourth intercostal arteries via branches that perforate the thoracic wall and overlying muscle

Venous Drainage:

Veins draining the breast parallel the arteries and ultimately drain into the axillary, internal thoracic, and intercostal veins.

Innervation

Innervation of the breast is via anterior and lateral cutaneous branches of the second to sixth intercostal nerves. The nipple is innervated by the fourth intercostal nerve.

Breasts in men

The breast in men is rudimentary and consists only of small ducts, often composed of cords of cells, that normally do not extend beyond the areola.

Clinical Notes:

  1. Peu the orange or an orange peel appearance occurs as a result of breast cancer where there is an appearance of puffy skin between dimple pores. These arise as a result of cancerous invasion and fibrosis which pulls on Cooper’s ligaments.

  2. Metastasis occurs as axillary lymph nodes are common metastatic sites from breast cancer due to how lymphatic drainage occurs in this area.