WHAT IS A BREAST?
Breasts are made up of a few different components. On the outside there is skin, which is the same as skin elsewhere on the body, and is susceptible to the same range of skin conditions, such as eczema, psoriasis, etc.
The central area of the breast is different. It is made up of a little knob of specialized skin, called the nipple. This is darker in colour, and contains the openings of the many ducts which connect with the breast tissue underneath. The skin of the nipple and the areola (which is the circle of darker skin around the nipple) is sensitive, and often becomes harder when stimulated by touch, or cold temperature, or when a woman is sexually aroused. The areola also has special glands in it. They are sometimes called Montgomery’s glands, and may be more prominent during pregnancy, when the skin of the areola and nipple also become darker. These areolar glands, which usually only measure a few millimetres, make oily secretions during pregnancy. This helps to lubricate and protect the skin of the nipple and areola.
Under the skin is breast tissue, which can be firm, slippery, granular, or globby in texture. Different women’s breasts may have slightly different (but still normal) textures. The texture may change in response to different hormone levels at different times of the menstrual cycle, or during pregnancy. The breast tissue is glandular tissue, which means that its function is to make secretions, in this case milk. The secretions made in the glands of the breast are drained via a system of ducts, which eventually drain to the openings in the nipple.
The breast tissue is arranged in a circle, like half an orange sitting on the chest wall. Like an orange, there are separate segments, divided by thin fibrous bands. There is usually a little extension of tissue up towards the axilla (armpit) on cither side. This is called the axillary tail, and should be included in breast examinations.
Embedded around the glandular tissue is a varying amount of fat. This is ordinary fatty tissue, and in most people makes up the bulk of the breast, except during pregnancy and breast feeding, when the glandular tissue enlarges. There are ligaments which help to support the breast on the chest wall. These may stretch a little with age and increased breast size (as happens during pregnancy).
The chest wall has layers of muscle overlying ribs. The pectoral muscles are the main ones under the breast. The blood supply to and from the breasts is via a system of blood vessels running along the chest wall from different directions.
An important consideration in the breasts is the lymphatic drainage. Lymph vessels are a bit like blood vessels, but they drain lymphatic fluid, which is clear, from the tissues to lymph glands (also known as nodes). There are lymph nodes and vessels all over the body. Most of the breast drains to the collection of lymph glands which live in the axilla. Lymph glands act like little customs check points, where the customs officers are white blood cells, prepared to detect and fight infections and inflammation. For example, if there is an infection in the breast, and an area becomes red and warm and sore, the lymph nodes in the axilla will become active, enlarging in response to the infection, as they make more infection-fighting white cells. In the same way the glands in the neck usually enlarge when there is a throat infection.
The lymphatic drainage of the breast is important because one of the ways cancers can spread is via the lymph system. If a woman is found to have breast cancer, doctors will try to assess if it has already spread. One of the first places it is likely to go is to the axillary lymph nodes. This is also why the armpit should be examined in breast examination, as enlarged or hard lymph glands may give a clue to underlying breast disease.
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