The breasts

The breasts sit on top of the upper ribs and a large chest muscle. They cover the area from the collarbone (clavicle), to the armpit (axilla) and across to the breastbone (sternum). Some breast tissue extends into the armpit and is called the axillary tail.

Female breasts are mostly made up of:

• lobes – each breast has 12–20 sections called lobes
• lobules – each lobe contains glands that can produce milk; these milk glands are called lobules or glandular tissue
• ducts – the lobes and lobules are connected by fine tubes called ducts; the ducts carry milk to the nipples when breastfeeding
• fatty/fibrous tissue – all breasts contain some fatty or fibrous tissue (including connecting tissue called stroma), no matter what their size.

Most younger women have dense or thicker breasts, because they contain more lobules than fat. Male breasts have ducts and fatty/fibrous tissue. They contain no, or only a few, lobes and lobules.

The lymphatic system

The lymphatic system is an important part of the immune system, and protects against disease and infection. Working like a drainage system, it removes fluid from body tissues back into the blood. It is made up of a network of thin tubes called lymph vessels. These lymph vessels connect to groups of small, bean-shaped lymph nodes (or glands).

There are lymph nodes throughout the body, including in the armpit, neck, abdomen, groin and near the breastbone. The first place breast cancer cells usually spread to is the axillary lymph nodes in the armpit.

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