Page 174 - Clinical Anatomy

ECA3 7/18/06 6:44 PM Page 159

The female breast

The female breast overlies the 2nd to the 6th rib; two-thirds of it rests on
pectoralis major, one-third on serratus anterior, while its lower medial edge
just overlaps the upper part of the rectus sheath.

Structure

The breast is made up of 15–20 lobules of glandular tissue embedded in fat;
the latter accounts for its smooth contour and most of its bulk. These
lobules are separated by fibrous septa running from the subcutaneous
tissues to the fascia of the chest wall (the ligaments of Cooper).
Each lobule drains by its lactiferous duct on to the nipple, which is sur-
rounded by the pigmented areola. This area is lubricated by the areolar
glands of Montgomery; these are large, modified sebaceous glands which
may form sebaceous cysts which may, in turn, become infected.
The male breast is rudimentary, comprising small ducts without alveoli
and supported by fibrous tissue and fat. Insignificant it may be, but it is still
prone to the major diseases that affect the female organ.

Blood supply
1◊◊From the axillary artery via its lateral thoracic and acromiothoracic
branches.
2◊◊From the internal thoracic (internal mammary) artery via its perforating
branches; these pierce the first to the fourth intercostal spaces, then traverse
pectoralis major to reach the breast along its medial edge. The first and
second perforators are the largest of these branches.
3◊◊From the intercostal arteries via their lateral perforating branches; a
relatively unimportant source.
The venous drainage is to the corresponding veins.

Lymphatic drainage
This is of considerable importance in the spread of breast tumours.
The lymph drainage of the breast, as with any other organ, follows the
pathway of its blood supply and therefore travels:
1◊◊along tributaries of the axillary vessels to axillary lymph nodes;
2◊◊along the tributaries of the internal thoracic vessels, piercing pectoralis
major to traverse each intercostal space to lymph nodes along the internal
mammary chain; these also receive lymphatics penetrating along the lateral
perforating branches of the intercostal vessels.
Although the lymph vessels lying between the lobules of the breast
freely communicate, there is a tendency for the lateral part of the breast to
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