Breast

Breast
The milk-engorged breast of a pregnant woman
Latin	mamma (mammalis “of the breast”) [1]
Artery	internal thoracic artery
Vein	internal thoracic vein

This article is about the human breast. For other animals, see Udder and Mammary gland. "Boobs" redirects here. For other uses, see Boob (disambiguation). For other uses, see Breast (disambiguation)

The breast is the upper ventral region of the torso of a primate, in left and right sides, which in a female contains the mammary gland that secretes milk used to feed infants.

Both men and women develop breasts from the same embryological tissues. However, at puberty, female sex hormones, mainly estrogen, promote breast development which does not occur in men due to the higher level of testosterone. As a result, women's breasts become far more prominent than those of men.

Etymology

The English word breast derives from the Old English word brēost (breast, bosom) from Proto-Germanic breustam (breast), from the Proto-Indo-European base bhreus– (to swell, to sprout).^[2] The breast spelling conforms to the Scottish and North English dialectal pronunciations.^[3]

Anatomy

The Breast: cross-section scheme of the mammary gland.
1. Chest wall
2. Pectoralis muscles
3. Lobules
4. Nipple
5. Areola
6. Milk duct
7. Fatty tissue
8. Skin

Morphology

The human breast has two aspects — the functional and the anatomic

I. The functional breast

The breast is an apocrine gland that produces milk to feed an infant child; for which the nipple of the breast is centred in (surrounded by) an areola (nipple-areola complex, NAC), the skin color of which varies from pink to dark brown, and has many sebaceous glands. For its offspring-feeding functions as a mammary gland, the lactiferous ducts that produce the fatty breast milk are distributed throughout the body of the breast; approximately two-thirds of the lactiferous tissue is within 30-mm of the base of the nipple. In each breast, 4–18 lactiferous ducts drain to the nipple; the milk-glands-to-fat ratio is 2:1 in a lactating woman, and 1:1 in a non-lactating woman. In addition to the milk glands, the breast also is composed of connective tissues (collagen, elastin), white fat, and the suspensory Cooper's ligaments. Sensation in the breast is provided by the peripheral nervous system innervation, by means of the front (anterior) and side (lateral) cutaneous branches of the fourth-, the fifth-, and the sixth intercostal nerves, while the T-4 nerve (Thoracic spinal nerve 4), which innervates the dermatomic area, supplies sensation to the nipple-areola complex.^[4][5]

II. The anatomic breast

A woman’s breasts overlay the pectoralis major muscles and usually extend from the level of the second rib to the level of the sixth rib in the front of the human rib cage; thus, the breasts cover much of the chest area and the chest walls. At the front of the chest, the breast tissue can extend from the clavicle (collarbone) to the middle of the sternum (breastbone). At the sides of the chest, the breast tissue can extend into the axilla (armpit), and can reach as far to the back as the latissimus dorsi muscle, extending from the lower back to the humerus bone (the longest bone of the upper arm). As a mammary gland, the breast is an inhomogeneous anatomic structure composed of layers of different types of tissue, among which predominate two types: (i) adipose tissue and (ii) glandular tissue, which effects the lactation functions of the breasts.

Morphologically, the breast is a cone with the base at the chest wall, and the apex at the nipple, the center of the NAC (nipple-areola complex). The superficial tissue layer (superficial fascia) is separated from the skin by 0.5–2.5 cm of subcutaneous fat (adipose tissue). The suspensory Cooper’s ligaments are fibrous-tissue prolongations that radiate from the superficial fascia to the skin envelope. The adult breast contains 14–18 irregular lactiferous lobes that converge to the nipple, to ducts 2.0–4.5 mm in diameter; the milk ducts (lactiferous ducts) are immediately surrounded with dense connective tissue that functions as a support framework. The glandular tissue of the breast is biochemically supported with estrogen; thus, when a woman reaches menopause (cessation of menstruation) and her body estrogen levels decrease, the milk gland tissue then atrophies, withers, and disappears, resulting in a breast composed of adipose tissue, superficial fascia, suspensory ligaments, and the skin envelope.

The dimensions and the weight of the breast vary among women, ranging approximately 500–1,000 gm each; thus, a small-to-medium-sized breast weighs 500 gm or less; and a large breast weighs approximately 750–1,000 gm. The tissue composition ratios of the breast likewise vary among women; some breasts have greater proportions of glandular tissue than of adipose or connective tissues, and vice versa; therefore the fat-to-connective-tissue ratio determines the density (firmness) of the breast. In the course of a woman’s life, her breasts will change size, shape, and weight, because of the hormonal bodily changes occurred in thelarche (pubertal breast development), menstruation (fertility), pregnancy (reproduction), the breast-feeding of an infant child, and the climacterium (the end of fertility).^[6][7][8]

Lymphatic drainage

Approximately 75 per cent of the lymph from the breast travels to the ipsilateral (same-side) axillary lymph nodes, whilst 25 per cent of the lymph travels to the parasternal nodes (beside the sternum bone), to the other breast, and to the abdominal lymph nodes. The axillary lymph nodes include the pectoral (chest), subscapular (under the scapula), and humeral (humerus-bone area) lymph-node groups, which drain to the central axillary lymph nodes and to the apical axillary lymph nodes. The lymphatic drainage of the breasts is especially relevant to oncology, because breast cancer is a cancer common to the mammary gland, and cancer cells can metastasize (break away) from a tumour and be dispersed to other parts of the woman’s body by means of the lymphatic system.

Shape and support

The topography of the breasts indicate the glandular body, the nipple-areola complex (NAC), and the inframammary fold (IMF).

The morphologic variations in the size, shape, volume, tissue density, pectoral locale, and spacing of the breasts determine their natural shape, appearance, and configuration upon the chest of a woman; yet such features do not indicate its mammary-gland composition (fat-to-milk-gland ratio), nor the potential for nursing an infant child.^[9][10] The size and the shape of the breasts are influenced by normal-life hormonal changes (thelarche, menstruation, pregnancy, menopause) and medical conditions (e.g. virginal breast hypertrophy).^[11] The shape of the breasts is naturally determined by the support of the suspensory Cooper's ligaments, the underlying muscle and bone structures of the chest, and the skin envelope. The supensory ligaments sustain the breast from the clavicle (collarbone) and the clavico-pectoral fascia (collarbone and chest), by traversing and encompassing the fat and milk-gland tissues, the breast is positioned, affixed to, and supported upon the chest wall, while its shape is established and maintained by the skin envelope.

The base of each breast is attached to the chest by the deep fascia over the pectoralis major muscles. Some breasts are mounted high upon the chest wall, are of rounded shape, and project almost horizontally from the chest, which features are common to girls and women in the early stages of thelarchic development, the sprouting of the breasts. In the high-breast configuration, the dome-shaped and the cone-shaped breast is affixed to the chest at the base, and the weight is evenly distributed over the base area. In the low-breast configuration, a proportion of the breast weight is supported by the chest, against which rests the lower surface of the breast, thus is formed the inframammary fold (IMF). Because the base is deeply affixed to the chest, the weight of the breast is distributed over a greater area, and so reduces the weight-bearing strain upon the chest, shoulder, and back muscles that bear the weight of the bust. The chest (thoracic cavity) progressively slopes outwards from the thoracic inlet (atop the breastbone) and above to the lowest ribs that support the breasts. The inframammary fold, where the lower portion of the breast meets the chest, is an anatomic feature created by the adherence of the breast skin and the underlying connective tissues of the chest; the IMF is the lower-most extent of the anatomic breast. In the course of thelarche, some girls develop breasts the lower skin-envelope of which touches the chest below the IMF, and some girls do not; both breast anatomies are statistically normal morphologic variations of the size and shape of women’s breasts.^[12]

Development

The Tanner Scale indicates the five development stages of the secondary sex characteristics (breasts and pubic hair) of girls and women.

On the skin envelope of the breast, stretch marks indicate the relative-size increments and decrements occurred during the life of the woman.

From pert to pooped: the seven stages of breast ptosis.

The basic morphological structure of the human breast — female and male — is determined during the prenatal development stage. For a girl in puberty, during thelarche (the breast-development stage), the female sex hormones (principally estrogens) promote the sprouting, growth, and development of the breasts, in the course of which, as mammary glands, they grow in size and volume, and usually rest on her chest; these development stages of secondary sex characteristics (breasts, pubic hair, etc.) are illustrated in the five-stage Tanner Scale.^[13] During thelarche, the developing breasts sometimes are of unequal size, and usually the left breast is slightly larger; said condition of asymmetry is transitory and statistically normal to female physical and sexual development.^[14] Moreover, breast development sometimes is abnormal, manifested either as overdevelopment (e.g. virginal breast hypertrophy) or as underdevelopment (e.g. tuberous breast deformity) in girls and women; and manifested in boys and men as gynecomastia (woman's breasts), the consequence of a biochemical imbalance between the normal levels of the estrogen and testosterone hormones of the male body.^[15]

Asymmetry

Approximately two (2) years after the pubertal occurrence of a girl’s first menstrual cycle, the hormone oestrogen stimulates the development and growth of the glandular, fat, and suspensory tissues that compose the breast; and continues for approximately four (4) years until establishing the final shape of the the breast (size, volume, density) when she is a woman of approximately 21 years of age.^[10] Approximately 90 per cent of women possess breasts that are asymmetrical, either in size, volume, or relative position upon the chest; whilst notable breast asymmetry — a breast-size difference of at least one brassière-cup size — is present in 25 per cent of women.^{[9][10][16][17][18][19]} For approximately 5–10 per cent of women, the asymmetry of the breasts is notably different, with the left breast usually bigger in 62 per cent of the women. The asymmetry can be manifested in the size of the breast, the position of the nipple-areola complex (NAC), the angle of the breast, and the position of the inframammary fold, where the breast meets the chest. The usual resolution for such conditions is corrective mammoplasty, such as mastopexy, breast reduction, or breast augmentation, which treatment is determined by the particular form of breast asymmetry to correct.^[10][20]

Hormonal change

Because the breasts are principally composed of adipose tissue, which surrounds the milk glands, their sizes and volumes fluctuate according to the hormonal changes particular to thelarche (sprouting of breasts), menstruation (egg production), pregnancy (reproduction), lactation (feeding of offspring), and menopause (end of menstruation). For example, during the menstrual cycle, the breasts are enlarged by premenstrual water retention; during pregnancy the breasts become enlarged and denser (firmer) because of the prolactin-caused organ hypertrophy, which begins breast milk production, increases the size of the nipples, and darkens the skin color of the nipple-areola complex (NAC); these changes continue during the lactation and the breastfeeding periods. Afterwards, the breasts generally revert to their pre-pregnancy size, shape, and volume, yet might present stretch marks and breast ptosis. At menopause, the breasts can decrease in size when the levels of circulating estrogen decline, followed by the withering of the adipose tissue and the milk glands. Additional to such natural biochemical stimuli, the breasts can become enlarged consequent to an adverse side effect of combined oral contraceptive pills; and the size of the breasts can also increase and decrease in response to the body weight fluctuations of the woman. Moreover, the physical changes occurred to the breasts usually are recorded in the stretch marks of the skin envelope; they are historical indicators of the increments and the decrements of the size and the volume of a woman’s breasts throughout the course of her life.

Breast ptosis

Main article: Ptosis (breasts)

The prolapsation, the falling forward, of the breasts occurs in consequence to their weight, the loosening of the suspensory Cooper's ligaments, and the force of gravity of the Earth. The relative relationship of the position of the nipple to the inframammary fold (IMF) is described as the condition of breast ptosis, and the degree of sagging is determined by the distance from the nipple to the sternal notch (the central, upper border of the sternum bone). In the young woman, the nipple-to-sternal-notch measurement is 21 cm., which is the usual anthropometric number applied to assess breast ptosis and breast symmetry. The apex of the breast, which includes the nipple, can have a flat angle of projection (180 degrees) or acute angle of projection (>180 degrees), yet the apex rarely has an angle greater than 60 degrees. The angle of the breast-tip is partly determined by the tautness of the suspensory Cooper’s ligaments, therefore, the angle of the breast apex becomes a flat, obtuse angle (<180 degrees) when the woman lies supine (on her back), while the base-to-length ratio of the breast ranges from 0.5 to 1.0.

Functions and health

Lactation

Main article: Breastfeeding

The functional breast nourishing an infant girl.

The primary function of the breasts — as mammary glands — is the feeding and the nourishing of an infant child with breast milk during the maternal lactation period. The round shape of the breast helps to limit the loss of maternal body heat, because milk production depends upon a higher-temperature environment for the proper, milk-production function of the mammary gland tissues, the lactiferous ducts. Regarding the shape of the breast, the study The Evolution of the Human Beast (2001) proposed that the rounded shape of a woman's breast evolved to prevent the sucking infant offspring from suffocating while feeding at the teat; that is, because of the human infant's small jaw, which did not project from the face to reach the nipple, he or she might block the nostrils against the mother's breast if it were of a flatter form (cf. chimpanzee); theoretically, as the human jaw receded into the face, the woman's body compensated with round breasts.^[21]

In a woman, the condition of lactation unrelated to pregnancy can occur as galactorrhea (spontaneous milk flow), and because of the adverse effects of drugs (e.g. antipsychotic medications), of extreme physical stress, and of endocrine disorders. In a newborn infant, the capability of lactation is consequence of the mother's circulating hormones (prolactin, oxytocin, etc.) in his or her blood stream, which were introduced by the shared circulatory system of the placenta; neonatal milk, the milk from a lactating infant, is also known as witch's milk. In men, the mammary glands are also present in the body, but normally remain undeveloped because of the hormone testosterone, however, when male lactation occurs, it is considered a pathological symptom of a disorder of the pituitary gland.

Reproduction

In considering the human animal, zoologists proposed that the human female — Woman — is the only primate that possesses permanent, full-form breasts when not pregnant, the opposite case of most mammal females that develop full breasts only when pregnant. The zoologist Desmond Morris proposed that the rounded shape of a woman's breasts evolved as frontal, secondary sex characteristic that is a sexual-attraction counterpart to the buttocks, and so encouraged frontal copulation. The reason being that, while other primates mate by means of the rear-entry position, the upright, bipedal human being was likelier to successfully copulate face to face. As an ethologist, Morris further proposed that breasts — a secondary sex characteristic located on the woman's chest — encouraged face-to-face sexual intercourse that led to the establishment of an emotional bond between man and woman; social progress from an essentially procreational function of human biology.^[22] Furthermore, the symmetry of the breasts, and the general symmetry of the human body, influence what men and women consider physical attractiveness in a mate with whom to reproduce. About which bodily beauty, evolutionary psychology proposes that a symmetrical body signals to a potential mate that he or she is genetically healthy, and so is the product of a morphologically stable line of people who physically developed without interference by disease. Therefore, because the breasts are especially sensitive to developmental interference (genetic and environmental), breast symmetry indicates a woman of good health and thus of good breeding stock, who shall successfully bear more (surviving) children than will a woman with asymmetrical breasts.^[23]

Mammary diseases

Main article: Breast disease

Because the breast is subject to abnormal conditions, such as macromastia and gigantomastia (overdeveloped breasts), micromastia (underdeveloped breasts), breast cancer, et cetera, for a woman, the style-of-life factors that can minimize the risks of breast disease are regular breast-examinations by a physician, mammogram monitoring, personal breast examination, a balanced diet with a minimal animal-fat content (e.g. cholesterol), and regular physical exercise.^[24]

Cultural aspects

Anthropomorphic geography

The summit viewed from the north-west slope of one of the Maiden Paps, Caithness, Scotland.

Main article: Breast-shaped hill

There are many mountains named after the breast, because they resemble it in appearance, and so are objects of religious and ancestral veneration as a fertility symbol and of well-being. In Asia, there was "Breast Mountain", which had a cave where the Buddhist monk Bodhidharma (Da Mo) spent much time in meditation.^[25] Other such breast mountains are: Mount Elgon on the Uganda-Kenya border, Beinn Chìochan in Scotland, the "Bundok ng Susong Dalaga" (Maiden's breast mountains) in Talim Island, Philippines, the twin hills known as the Paps of Anu (Dá Chích Anann or the breasts of Anu), near Killarney in Ireland, the 2,086 m high Tetica de Bacares or "La Tetica" in the Sierra de Los Filabres, Spain, and Khao Nom Sao in Thailand, Cerro Las Tetas in Puerto Rico and the Breasts of Aphrodite in Mykonos, among many others. In the United States, the Teton Range is named after the French word for "breast".^[26]

Art history

A Cretan Snake Goddess from the Minoan Civilization, ca. 1600 BC.

In European pre-historic societies, sculptures of female figures with pronounced or highly exaggerated breasts were common. A typical example is the so-called Venus of Willendorf, one of many Paleolithic Venus figurines with ample hips and bosom. Artifacts such as bowls, rock carvings and sacred statues with breasts have been recorded from 15,000 BC up to late antiquity all across Europe, North Africa and the Middle East. Many female deities representing love and fertility were associated with breasts and breast milk. Figures of the Phoenician goddess Astarte were represented as pillars studded with breasts. Isis, an Egyptian goddess who represented, among many other things, ideal motherhood, was often portrayed as suckling pharaohs, thereby confirming their divine status as rulers. Even certain male deities representing regeneration and fertility were occasionally depicted with breast-like appendices, such as the river god Hapy who was considered to be responsible for the annual overflowing of the Nile. Female breasts were also prominent in the Minoan civilization in the form of the famous Snake Goddess statuettes. In Ancient Greece there were several cults worshipping the "Kourotrophos", the suckling mother, represented by goddesses such as Gaia, Hera and Artemis. The worship of deities symbolized by the female breast in Greece became less common during the first millennium. The popular adoration of female goddesses decreased significantly during the rise of the Greek city states, a legacy which was passed on to the later Roman Empire.^[27]

During the middle of the first millennium BC, Greek culture experienced a gradual change in the perception of female breasts. Women in art were covered in clothing from the neck down, including female goddesses like Athena, the patron of Athens who represented heroic endeavor. There were exceptions: Aphrodite, the goddess of love, was more frequently portrayed fully nude, though in postures that were intended to portray shyness or modesty, a portrayal that has been compared to modern pin ups by historian Marilyn Yalom.^[28] Although nude men were depicted standing upright, most depictions of female nudity in Greek art occurred "usually with drapery near at hand and with a forward-bending, self-protecting posture".^[29] A popular legend at the time was of the Amazons, a tribe of fierce female warriors who socialized with men only for procreation and even removed one breast to become better warriors (the idea being that the right breast would interfere with the operation of a bow and arrow). The legend was a popular motif in art during Greek and Roman antiquity and served as an antithetical cautionary tale.

Body image

Main article: Breast implant

Breast augmentation: the pre-operative (left) and the post-operative (right) aspects of a procedure for implanting breast implants.

Breast reduction: the pre-operative (left) and the post-operative (right) aspects of a reduction mammoplasty procedure.

Women regard their breasts, which are female secondary sex characteristics, as important to their sexual attractiveness, as a sign of femininity that is important to their sense of self. So, when a woman considers her breasts deficient in some respect, she might choose to undergo a plastic surgery procedure to enhance them, either to have them augmented or to have them reduced, or to have them reconstructed if she suffered a deformative disease, such as breast cancer.^[30] After mastectomy (the removal of a diseased breast), the reconstruction of the breast or breasts is done with breast implants or autologous tissue transfer, using fat and tissues from the abdomen, which is performed with a TRAM flap or with a back (latissiumus muscle flap). Breast reduction surgery is a common procedure that involves removing excess breast tissue, fat, and skin, and the repositioning of the nipple-areola complex (NAC).

Cosmetic improvement procedures include breast lift (mastopexy), breast augmentation with implants, and combination procedures; the two types of available breast implants are models filled with silicone gel, and models filled with saline solution. These types of breast surgery can also repair inverted nipples by releasing milk duct tissues that have become tethered. Furthermore, in the case of the obese woman, a breast lift (mastopexy) procedure, with or without a breast volume reduction, can be part of an upper-body lift and contouring for the woman who has undergone massive body weight loss.

Surgery of the breast presents the health risk of interfering with the ability to breast-feed and infant child, which might include consequences such as altered sensation in the nipple-areola complex, interference with mammography (breast x-rays images) when there are breast implants present in the breasts. Regarding breast-feeding capability after breast reduction surgery, studies reported that women who underwent breast reduction can retain the ability to nurse an infant child, when compared to women in a control group who underwent breast surgery using a modern pedicle surgical technique.^{[31][32][33][34][35][36][37]} Plastic surgery organizations generally discourage elective cosmetic breast augmentation surgery for teenaged girls, because, at that age range, the volume of the breast tissues (milk glands and fat) can continue to grow as the girl matures to womanhood. Breast reduction surgery for teenaged girls, however, is a matter handled according to the particulars of the case of hypoplasia. (see: breast hypertrophy)

Clothing

See also: Toplessness, Cleavage (breasts), Modesty, Naturism, and Exhibitionism

Per the social norms of northern Namibia, a bare-breasted Himba woman wears a traditional headdress and clothes.

Breasts are flexible and their shape can, within individual limits, be molded by clothing, such as foundation garments. A brassiere (bra), for example, can give breast support (i.e. raise the breasts to compensate for any sag) and alter the shape of the breasts. There is some debate over whether such support is desirable. A long term clinical study showed that women with large breasts can suffer myalgia, or shoulder pain as a result of bra straps,^[38] although a well fitting bra should support most of the breasts' weight with proper sized cups and back band rather than on the shoulders.

The social norm of most cultures is for breasts to be covered in public, though the extent of expected coverage varies with context. Some religions afford the breast a special status, either in formal teachings or in symbolism. Islam forbids public exposure of the female breasts.^[39] Many cultures associate breasts primarily with sexuality and tend to regard bare breasts in terms of modesty and decency. Other cultures view female toplessness as acceptable, and in some countries the social norm is for women to be bare breasted, such as the Himba in northern Namibia. In some African cultures, for example, the thigh is regarded as highly sexualised and never exposed in public, but breast exposure is not taboo. Opinion on the exposure of breasts often depends on the place and context, and in some Western societies exposure of breasts on a beach may be acceptable, but not, for example, in town centres. In some areas the prohibition against the display of a woman's breasts only applies to the exposure of nipples.

In Western culture, a woman's breast-feeding her child in public often exposed her to legal and social sanctions for indecent exposure and for violating public dress codes, which prohibitions have been relaxed and eliminated as religious definitions of “female modesty” have been deleted from the legal system in the course of establishing cultural and legal gender equality. In the U.S., the topfreedom equality movement sought and won the redress of such sexism, in the case of People v. Santorelli (1992) wherein the New York State Court of Appeals ruled that the indecent exposure laws of the State of New York did not apply to a bare-breasted woman. Likewise, similar legal (gender equality) efforts succeeded in most of Canada in the 1990, while in Australia and much of Europe, bare-breasted women are legal, and culturally acceptable, at public beaches and piscines.

Sexual characteristic

See also: Mammary intercourse and Breast fetishism

In some cultures breasts play a role in human sexual activity. Breasts and especially the nipple are one of a woman's erogenous zones. They are sensitive to the touch as they have many nerve endings; and it is common to press or massage them with hands or orally before or during sexual activity. Some women can achieve breast orgasms. In the ancient Indian work the Kama Sutra, light scratching of the breasts with nails and biting with teeth are considered erotic.^[40] On sexual arousal breast size increases, venous patterns across the breasts become more visible, and nipples harden. Compared to other primates, human breasts are proportionately large throughout adult females' lives. Some writers have suggested that they may have evolved as a visual signal of sexual maturity and fertility.^[41]

Many people regard the female human body, of which breasts are an important aspect, to be aesthetically pleasing, as well as erotic. Research conducted at the Victoria University of Wellington showed that breasts are often the first thing men look at, and for a longer time than other body parts.^[42] The writers of the study had initially speculated that the reason for this is due to endocrinology with larger breasts indicating higher levels of estrogen and a sign of greater fertility,^[42][43] but the researchers said that "Men may be looking more often at the breasts because they are simply aesthetically pleasing, regardless of the size."^[42]

Many people regard bare female breasts to be erotic, and they can elicit heightened sexual desires in some men in some cultures. Some people show a sexual interest in female breasts distinct from that of the person, which may be regarded as a breast fetish.^[44]

Symbolism

In Christian iconography, some works of art depict women with their breasts in their hands or on a platter, signifying that they died as a martyr by having their breasts severed; one example of this is Saint Agatha of Sicily. In Silappatikaram, Kannagi tears off her left breast and flings it on Madurai, cursing it, causing a devastating fire.

See also

• Intimate part
• Milk line
• Multiple breast syndrome

References

Notes

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2. ^ Indo-European Lexicon: Pokorny Master PIE Etyma. Utexas.edu. Retrieved on 2011-04-22.
3. ^ Online Etymology Dictionary. Etymonline.com. Retrieved 22 April 2011.
4. ^ Introduction to the Human Body, Fifth Edition. John Wiley & Sons, Inc.: New York, 2001. 560.
5. ^ Ramsay DT, Kent JC, Hartmann RA, Hartmann PE (June 2005). "Anatomy of the Lactating Human Breast Redefined with Ultrasound Imaging". Journal of Anatomy 206 (6): 525–534. doi:10.1111/j.1469-7580.2005.00417.x. PMC 1571528. PMID 15960763. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1571528. 
6. ^ Pamplona DC, de Abreu Alvim C. Breast Reconstruction with Expanders and Implants: a Numerical Analysis. Artificial Organs 8 (2004), pp. 353–356.
7. ^ Grassley JS. Breast Reduction Surgery: What every Woman Needs to Know. Lifelines 6 (2002), pp. 244–249.
8. ^ Azar FS. A Deformable Finite Element Model of the Breast for Predicting Mechanical Deformations under External Perturbations. (doctoral thesis) Department of Bioengineering, University of Pennsylvania, Philadelphia Penn., USA, 2001.
9. ^ ^{a b} Jelovsek, Frederick R.. "Breast Asymmetry—When Does it Need Treatment?". http://www.wdxcyber.com/nbreast3.htm. Retrieved January 19, 2011. 
10. ^ ^{a b c d} Goddard, Kay (May 10, 2011). "I May Have Been the Ultimo Bra Girl, but One of my Breasts was a B-cup and the other was a D". The Daily Mail. http://www.dailymail.co.uk/health/article-1384595/Katie-Green-I-Ultimo-bra-girl-I-suffered-breast-asymmetry.html. Retrieved 18 May 2011. 
11. ^ Wood K, Cameron M, Fitzgerald K (2008). "Breast Size, Bra Fit and Thoracic Pain in Young Women: A Correlational Study". Chiropractic & Osteopathy 16: 1. doi:10.1186/1746-1340-16-1. PMC 2275741. PMID 18339205. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2275741. 
12. ^ Boutros S, Kattash M, Wienfeld A, Yuksel E, Baer S, Shenaq S (September 1998). "The Intradermal Anatomy of the Inframammary Fold". Plastic and Reconstructive Surgery 102 (4): 1030–1033. doi:10.1097/00006534-199809040-00017. PMID 9734420. http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?issn=0032-1052&volume=102&issue=4&spage=1030. 
13. ^ Greenbaum AR, Heslop T, Morris J, Dunn KW (April 2003). "An Investigation of the Suitability of Bra fit in Women Referred for Reduction Mammaplasty". British Journal of Plastic Surgery 56 (3): 230–6. doi:10.1016/S0007-1226(03)00122-X. PMID 12859918. 
14. ^ Loughry CW et al. (1989). "Breast Volume Measurement of 598 Women using Biostereometric Analysis". Annals of Plastic Surgery 22 (5): 380–385. doi:10.1097/00000637-198905000-00002. PMID 2729845. 
15. ^ Olson, James Stuart (2002). Bathsheba's Breast: Women, Cancer and History. Baltimore: The Johns Hopkins University Press. p. 109. ISBN 0-8018-6936-6. OCLC 186453370. 
16. ^ Dolya, Gayane. "Breast Asymmetry". http://www.menstrual-cycle.info/137-Breast-asymmetry.html. Retrieved January 19, 2011. 
17. ^ "Breast Development". Massachusetts Hospital for Children. http://www.mgh.harvard.edu/children/adolescenthealth/articles/aa_breast_development.aspx. Retrieved 2010-6-2. ^{[dead link]}
18. ^ "Asymmetric Breasts". Channel 4. http://www.channel4embarrassingillnesses.com/conditions/asymmetric-breasts/. Retrieved 6-2-2010. 
19. ^ "Asymmetric Breasts". http://www.embarrassingissues.co.uk/AsymmetricBreasts.html. Retrieved 6-2-2010. 
20. ^ Losken A, Fishman I, Denson DD, Moyer HR, Carlson GW (December 2005). "An Objective Evaluation of Breast Symmetry and Shape Differences using 3-dimensional Images". Annals of Plastic Surgery 55 (6): 571–575. doi:10.1097/01.sap.0000185459.49434.5f. PMID 16327452. 
21. ^ Bentley, Gillian R. (2001). "The Evolution of the Human Breast". American Journal of Physical Anthropology 32 (38): 30. doi:10.1002/ajpa.1033. 
22. ^ Morris (1967), pp. 64–68.
23. ^ Wade, T. J. (2010). "The Relationships between Symmetry and Attractiveness and Mating Relevant Decisions and Behavior: A Review". Symmetry 2 (2): 1081. doi:10.3390/sym2021081.  edit
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Bibliography

• Hollander, Anne Seeing through Clothes. University of California Press, Berkeley. 1993 ISBN 0-52008-231-1
• Morris, Desmond The Naked Ape: a zoologist's study of the human animal Bantam Books, Canada. 1967
• Yalom, Marilyn A History of the Breast. Pandora, London. 1998 ISBN 0-86358-400-4

External links

• Media related to Breasts at Wikimedia Commons
• Images of female breasts
• Breast Cancer Treatment and Facts
• “Are Women Evolutionary Sex Objects?: Why Women Have Breasts”