Gross anatomy

Morphological features

The breast is situated within the subcutaneous tissue of the anterolateral chest wall. It extends from the second to the sixth rib and from the edge of the sternum to the mid-axillary line, overlying the pectoralis major, serratus anterior, upper part of the rectus sheath and external oblique muscles. The breast extends in a supero-lateral direction along the border of the pectoralis major muscle, through the foramen of Langer in the deep fascia of the axilla, to lie close to the pectoral group

Non-lactating

Lactiferous sinus

Lactiferous duct

Mammary lobules

Lactating

Lactating

Non-lactating

Lactiferous sinus

Lactiferous duct

Mammary lobules

Areola

Nipple

Figure 17.1. Anatomy of the breast and- chest wall. Permission from Essential Clinical Anatomy, Williams & Wilkins, Baltimore.

Supraclavicular lymph nodes

Subclavian lymph trunk

Areola

Nipple

Infraclavicular lymph nodes

Figure 17.1. Anatomy of the breast and- chest wall. Permission from Essential Clinical Anatomy, Williams & Wilkins, Baltimore.

of axillary lymph nodes. This is termed the axillary tail of Spence. The breast is separated from the muscles it overlies by the deep fascia. However, between the breast and the deep fascia is the retromammary space which contains loose areolar tissue. Supporting connective tissue strands pass between the dermal layer of the skin and the underlying breast. They are well developed in the upper aspect of the breast and are referred to as the suspensory ligaments of Cooper.

The nipple usually lies at the level of the fourth intercostal space and 15-20 lactiferous ducts open onto its surface through small openings. Surrounding the nipple is the areola which is made up of pigmented skin and subcutaneous tissue in which lie smooth muscle fibres. The epithelium contains sweat glands, sebaceous glands and accessory mammary glandular tissue (Figs 17.1 and 17.2).

Arterial supply and venous drainage

The blood supply to the breast is from the perforating branches of the internal thoracic artery (lateral edge of the sternum), the lateral thoracic artery and the pectoral branch of the acromiothoracic artery (the latter two derived from the axillary artery). In addition, there is also a variable blood supply from perforating branches of the intercostal arteries and from the subscapular artery. The venous drainage is through veins corresponding to the arterial supply.

Lymphatic drainage

The lymphatic drainage of the breast is predominantly through lymph vessels which are located in the interlobular connective tissues. These lymph vessels communicate with the cutaneous and subcutaneous lymphatic plexuses, the subareolar plexus of Sappey, and a plexus lying beneath the breast on the deep fascia covering the pectoralis major muscle. It has been estimated that approximately 75% of the lymph drainage of the breast is to the axillary groups of lymph nodes. These are the anterior (or pectoral nodes) which are situated along the lateral thoracic vessels, the posterior (or

Apical lymph nodes

Central lymph node

Pectorial lymph node

Lateral lymph nodes

Subscapular lymph nodes

Supraclavicular lymph nodes

Subclavian lymph trunk

Infraclavicular lymph nodes

Pectorial lymph node

Lateral lymph nodes

Subscapular lymph nodes

Deep cervical lymph nodes

Right lymphatic duct

Para-sternal lymph nodes

Subareolar lymphatic plexus

-To abdominal lymphatics

Figure 17.2. Anatomy of axilla. Permission from Gray's Anatomy, 35th edn., Churchill Livingston, p. 648, 1973.

Subareolar lymphatic plexus

Deep cervical lymph nodes

Right lymphatic duct

Para-sternal lymph nodes

-To abdominal lymphatics

Figure 17.2. Anatomy of axilla. Permission from Gray's Anatomy, 35th edn., Churchill Livingston, p. 648, 1973.

subscapular nodes) which are on the subscapular vessels, the central group of lymph nodes lying within the axilla, and the apical group sited at the apex of the axilla (Fig. 17.3).

These lymph nodes can be subdivided anatomically, depending on their relationship to the pectoralis minor muscle: level 1: nodes lying below the muscle; level 2: nodes lying behind the muscle and level 3: nodes above the muscle in the apex of the axilla. The lymphatic drainage from the apical nodes is to the supraclavicular and lower cervical groups of nodes. However, it is also recognised that 25% of the lymph drainage of the breast (medial aspect) is to the internal thoracic nodes and, in addition, some lymphatic drainage is through the lymphatics of the anterior abdominal wall.

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