Breast-nonmalignant - Normal anatomy

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Breast-nonmalignant

General

Normal anatomy of breast

Author: Nat Pernick, M.D. (see Authors page)

Revised: 24 September 2012, last major update March 2010

Definition

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● Covered by skin and subcutaneous tissue

● Separated from pectoralis muscle by fascia

● Composed of terminal duct lobular units (TDLU, terminal duct and lobule, has secretory function) plus mean 18-23 large ducts which drain into mean 5-9 ductal orifices (Cancer 2004;101:1947), often through a common opening (Breast Cancer Res Treat 2007;106:171, Eur Surg Res 2006;38:545)

● Large ducts subdivide into segmental ducts, subsegmental ducts and then lobules; lactiferous sinuses are apparently an artifact, and do not actually exist (J Anat 2005;206:525); this study changed commonly held views of anatomy (Wikipedia)

● External shape / size of the breast is not predictive of its internal anatomy or its lactation potential

Terminology

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● Also called mammary gland

Components

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Nipple:

● Mean diameter 11-13 mm, mean height 0.9 cm, mean diameter of areola is 4 cm (Aesthetic Plast Surg 2009;33:295, Am J Surg 2007;194:433)

Montgomery's tubercles:

● Areolar protuberances (10-20), more prominent during pregnancy; composed of ducts and sebaceous apparatus (Archives 1982;106:60)

TDLU:

● Site of origin of fibrocystic changes, hyperplasia, carcinoma (including most ductal carcinomas)

Ducts:

● Site of origin of solitary papillomas, duct ectasia, rarely ductal carcinoma

Regional lymph nodes:

● (a) axillary: interpectoral [Rotter’s] nodes, lymph nodes along axillary vein and its tributaries, lymph nodes within the breast

● (b) internal mammary: in the intercostal spaces along the edge of the sternum in the endothoracic fascia

● (c) supraclavicular lymph nodes are now considered regional

Lymph nodes:

● Occur normally in any quadrant; but should biopsy in cancer patients (Hum Path 2001;32:178)

● May be more than one sentinel node (Ann Surg Oncol 2008;15:863)

Gross images

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Nipple orifices, some cannulated with guide wires;

collecting vessels and lymphatics after dye injection into cadaver

Micro images

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Perforating lymphatic

Drawings

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Breast anatomy

Netter drawings (vasculature and lymphatics)

Regional lymph nodes-schematic

A: Pectoralis major muscle Regional lymph nodes
B: Axillary lymph nodes: levels I
C: Axillary lymph nodes: levels II
D: Axillary lymph nodes: levels III
E: Supraclavicular lymph nodes
F: Internal mammary lymph nodes

Radiograph of lymphatics Tracing of lymphatics

Supraclavicular fossa

Additional references

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● eMedicine

End of Breast-nonmalignant > General > Normal anatomy of breast

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