What is the structure of normal breasts?

The breast is located in front of the pectoralis major muscle on both sides of the chest, and its position is also related to age, body shape and breast development. The breasts of adult women are generally located between the second and sixth ribs of the chest, with the inner edge close to the sternum, the outer edge reaching the axillary front line, and reaching the axillary midline when the breasts are enlarged. The extremely long and narrow part outside the breast forms the axillary tail of the breast and extends to the armpit. The nipple of young women is generally located at the level of the fourth rib or the fifth rib, outside the clavicle midline1cm; The nipple of middle-aged women is located at the sixth intercostal level, outside the clavicle midline 1 to 2cm. Because there are great individual differences in the shape and position of breasts, the development of female breasts is also affected by age and various physiological periods. Therefore, it is unnecessary to avoid treating the shape and position of the breast that belongs to the normal range as pathological.

Ideological burden. Generally speaking, we should understand breasts from the following five aspects. 1. The internal structure of the breast is mainly composed of glands, ducts, adipose tissue and fibrous tissue. Its internal structure is like a small tree growing upside down. The surface of nipple is covered with a layer of scaly cuticular epithelium, and the epithelial layer is very thin. The nipple is composed of dense connective tissue and smooth muscle. The adipose tissue in the breast is wrapped around the breast to form a hemispherical whole. This layer of adipose tissue is called the adipose capsule. The breast is located between the superficial and deep layers of the superficial fascia under the skin. The superficial fascia extends into the breast tissue to form a cord-like interlobular septum, one end of which is connected with the fascia of the pectoral muscle, and the other end is connected with the skin to fix the breast in the subcutaneous tissue of the chest. Most of the breasts are located on the surface of pectoralis major, its deep lateral surface is located on the surface of serratus anterior, and its medial and lower parts are located on the fascia surfaces of oblique abdominis and rectus abdominis. In addition, there are abundant blood vessels, lymphatic vessels and nerves in the breast, which play a nutritional role and maintain metabolism, and have important surgical significance. 2. The development of breasts is a common feature of mammals, which generally grow in pairs and are symmetrical on both sides. There is only one pair of human breasts in the chest, which comes from ectoderm. From birth, breast development has gone through different stages such as infancy, adolescence, sexual maturity, pregnancy, lactation and menopause. In different periods, the level of endocrine hormones in the body is very different, which affects the development and physiological function of the breast. In infancy, the breast is basically in a "static" state and the glands are degenerated. Since puberty, influenced by various endocrine hormones, female breasts have entered the most active period of physiological development and functional activities in their lives. After going through puberty, the organizational structure of the breast has tended to be perfect, and it has entered a sexually mature breast. Pregnancy and breastfeeding are special physiological periods for women of childbearing age, when the mammary glands change to meet this special physiological demand. Since menopause, the physiological activity of breast has been weakened day by day. 3. Physiological function of breast Breast-feeding is the most basic physiological function of breast. Secondly, breasts are an important symbol of women's secondary sexual characteristics. Generally speaking, breasts begin to develop 2 ~ 3 years before menarche, that is to say, they begin to grow around 10 years old. This is the earliest secondary sexual characteristic, which marks the beginning of puberty for girls. In addition, breasts also have the characteristics of participatory activities. In sexual activities, the breast is the most sensitive organ for women except the genitals. 4. Endocrine hormones affecting the physiological function of the breast Breast is the target organ of many endocrine hormones. Therefore, the growth and development of breast and its various physiological functions depend on the interaction of various related endocrine hormones. If the secretion of one or more hormones is disordered, or the balance between various hormones is unbalanced, it will inevitably directly or indirectly affect the condition and physiological function of the breast. 5. The production of milk is secreted by mammary gland acinar cells. However, the secretion of milk needs the action of prolactin produced by secretory cells in the anterior pituitary, and the discharge of milk depends on the action of oxytocin produced by neurosecretory cells in the posterior pituitary. Of course, in the process of regulating milk secretion, there are many hormones such as estrogen, progesterone, growth hormone, thyroxine, adrenocortical hormone and insulin.