Topography and External Structure
The gland is located on the anterior thoracic wall. It lies on the surface of the pectoralis major muscle and partially extends over the serratus anterior muscle. The vertical boundaries of the organ extend from the level of the 3rd to the 6th rib, and the horizontal boundaries extend from the parasternal line to the anterior axillary line.
The external surface of the organ features characteristic structures:
- Nipple (papilla mammaria) — located in the very center. The openings of the lactiferous ducts open at its apex.
- Areola (areola mammae) — surrounds the nipple. The skin in this zone is heavily pigmented and contains specific sebaceous and sweat glands (glandulae areolares).
Internal Structure
The basis of the organ is formed by the body of the mammary gland (corpus mammae). It has a lobular structure and consists of 15–20 lobes (lobi glandulae mammariae). Strong connective tissue septa are located between the lobes, forming the framework of the organ.
Each individual lobe is subdivided into smaller structures — lobules (lobuli glandulae mammariae). It is within these lobules that the alveolar-tubular secretory units responsible for milk production are located.
A lactiferous duct (ductus lactifer) extends from each lobe toward the center of the gland. Before entering the nipple and opening on its surface, each such duct forms a local dilation — the lactiferous sinus (sinus lactifer), which serves as a small reservoir for the secretion.
Coverings and Fixation Apparatus
The glandular tissue itself is surrounded on all sides by masses of adipose and fibrous tissue, which determine the shape and volume of the organ.
To support the organ on the anterior thoracic wall, specialized connective tissue strands exist — the suspensory ligaments of the breast (ligg. suspensoria mammaria). These dense structures securely anchor the gland to the deep layers of the skin and underlying fascia. The posterior surface of the gland is separated from the pectoral fascia by a layer of loose connective tissue, which provides the organ with a degree of mobility.
Characteristics of the Male Mammary Gland
In males, the organ is termed mamma masculina. Normally, it is completely rudimentary and does not perform secretory functions. The male gland is represented only by a small amount of connective tissue interspersed with poorly developed, non-functioning ducts.
Blood Supply, Innervation, and Lymphatic Drainage
The blood supply to the organ is characterized by a multiplicity of sources. Arterial blood is supplied from branches of:
- Internal thoracic artery (a. thoracica interna).
- Lateral thoracic artery (a. thoracica lateralis).
- Intercostal arteries.
Venous drainage is carried out via corresponding veins accompanying the arteries.
Innervation is provided by branches of the intercostal nerves (nn. intercostales) and supraclavicular nerves (nn. supraclaviculares).
The lymphatic system plays a critically important role. The primary bulk of lymph from the mammary tissue drains predominantly into the axillary lymph nodes (nodi lymphatici axillares).