Breast Cancer Pain
Breast Anatomy and Physiology
The breasts or mammary glands are sometimes considered a part of the reproduction system. Structurally, they are modified sweat glands. They are composed of mainly fat, breast tissue, nerves, veins, arteries, and connective tissues.
The breast is usually situated on top of the pectoral major muscles covering the second rib to the sixth or seventh rib and extends from the sternum to the mid-axillary line. Breast tissue has an axillary tail which extends into the armpit region. Most breast cancer originates here. The nipple is usually level with the fourth intercostal space in men and nulliparous women.
The connective tissues (suspensory or Cooper's ligaments) and fat help protect a network of milk producing glands and blood vessels. The Cooper's ligaments divide the breast into compartments of fat. They also help give the breasts their size and shape. The size of the breast changes depend on the hormone levels of a woman menstrual cycle. It is normal for the right and the left breast to be different sizes. However, the size of the breasts does not affect their functionality. The main function of the breast is to produce milk for nursing babies.
The arteries and veins allow circulation through breast tissue. The lateral thoracic, internal thoracic, intercostal, and thoracoacromial arteries and veins supply oxygen and nutrients to the breasts as well as removing waste from the sites.
The nerves that go through the breasts are cutaneous innervation, medial pectoral, lateral pectoral, and long thoracic nerves. These provide sensory input from the breasts to the brain. They also carry referred pain signals from the heart therefore are clinically important in assessing heart attack. The cutaneous innervation of the breast is controlled by the anterior (T1-6) and medial (T2-7) branches of the intercostal nerves. The nipple and areola are supplied by the anterior and medial branches of the fourth intercostal nerve, the third and also fifth intercostal nerves. During mastectomy, these nerves are frequently damaged which may cause pain and conditions of abnormal sensation or function in the area. One such condition is winged scapula.
Lymphatic system in the breasts collects wastes and provides filtration of the fluid outside of the circulatory system. Nodes around the breasts are check stations that check lymph fluid for harmful substances and kill germs using immune cells. This system works via the five groups of axillary nodes, one group of interpectoral nodes, one group of parasternal nodes and ultimately subclavian lymph trunk. Since axillary nodes provide seventy five percent of drainage, they are usually the first to be invaded by cancer cells.
Externally, each breast has a nipple that is made of erectile muscle tissue. These muscle tissue raises the nipples in response to stimulation or breastfeeding. Surrounding the nipples are the areola and areolar glands. ...