Breast Anatomy and Lactation

Breast milk benefits

- Has all nutrients a baby needs in the first year of life Benefits for the baby - Lower rates of 1) allergies 2) ear and lung infections 3) obesity 4) sudden infant death - Healthier weight gain - Better neurocognitive development Benefits for mother - Reduces uterine bleeding - Burns calories - Reduces risk of 1) breast/ovarian/uterine cancer 2) osteoporosis 3) arthritis 4) T2DM 5) heart disease Free, chance for skin to skin contact

Label 2

dont need to know

Anatomy of the axilla

Border of axilla - Lateral, humerus - Anterior, pectoralis major and minor - Posterior, supscapularis, latissimus dorsi and teres major - Medial, serratus anterior - Base, Skin and axillary fascia - Apex, bound by clavicle, scapula and 1st rib Lymphatic drainage (axillary group; drains 85%, 15% internal mammary) - Lateral, along the axillary vein - Anterior, along the lateral thoracic vessels - Posterior, along the subscapular vessels - Central, beneath pec minor - Interpectoral (Rotter's), lying between pec major and pec minor muscles - Apical, apex of axilla

General

Breast tissue develops during puberty Made up of - adipose (fat) tissue - glandular tissue; alvoelus (modified sweat gland) + alveolar cells (make milk). Around alveolus are myoepithelial cells (squeeze down and push milk out the alveolus) - lactiferous ducts: passage ways which guide milk to nipple When the breasts are full of milk they become heavy and there are suspensory ligaments (Cooper's ligaments) that hold them up against the chest wall.

Milk letdown

- A conditioned reflex that usually starts when baby latches and suckles on nipple - A good latch is when the baby's mouth is wide open covering the areola with its lips flanged out, nipple at roof of mouth and tongue against bottom of areola - Mechanoreceptors in nipple sense this stimulation and send a signal via intercostal nerves to dorsal root ganglion then via SC to hypothalamus - Hypothalamus blocks prolactin inhibiting neurons from releasing dopamine which allows lactotrophic cells in the anterior pituitary to make prolactin - Hypothalamus also stimulates a group of hypothalamic paraventricular cells to make oxytocin which moves to posterior pituitary where its secreted - Prolactin stimulates alveolar cell milk production - Oxytocin stimulates the myoepithelial cells to contract to push the milk into the duct = milk let down - When baby cries the sound is registered in the mom's brain and a signal is sent to the hypothalamus to initiate the let down reflex as well

Contraindications to breastfeeding

- Certain medications - Illicut drugs: cocaine, heroin, cannabis - Alcohol should be minimized as can blunt milk letdown and affects the baby's development (should take place 2 hours after intake) - Smoking increase risk of SIDS and infant respiratory allergy - Even high doses of caffeine can alter baby's physiology - Maternal infections ex, HIV in high income settings but may be appropriate in low income settings where cost of formula and access to clean water is a challenge

Mammary (milk) lines

- In mammals, mammary gland and nipple development occur along two lines called milk lines which extend from the axilla to the inguinal region. - These appear as faint ridges in the embryo formed from invagination of ectoderm (7 weeks). - The majority of these lines disappear but a small portion in the thoracic region persist and penetrate the underlying mesenchyme. - These give rise to 16-24 sprouts in the thoracic region, which give rise to mammary buds, ultimately to become lactiferous ducts - only at puberty do alveoli form. - Occasionally accessory nipples and/or breast tissue develops, usually in the thoracic region but can occur anywhere along the milk lines

Development in pregnancy

- It isn't until pregnancy that there will be complete development of mammary function. - The end result is an intricate system of ductules within lobes that converge to lactiferous ducts. - The lactiferous ducts are around 2mm diameter but have the capacity to dilate up to 10mm with milk. They are easy to occlude. - There is also an increase in mammary blood flow and capillary formation around the lobes. - This occurs in what ever size breasts and therefore size of the breasts has no relation to functional capacity although it may indicate milk storage potential. - Overall the breasts enlarge, the areola darken (helps baby see the nipple), and montgomery glands produce lipoid fluid which moisterize the nipple - The placenta releases human palcental lactogen and progesterone. Anterior pituitary releases prolactin. All 3 stimulate growth of glandular tissue and prepares alveolar cells to make milk - Estrogen in pregnancy also leads to a proliferation of alveoli and ducts, the alveoli develop further and clusters of alveoli are surrounded by a contractile unit of myoepithelial cells. - Prolactin also stimulates milk let down but progesterone prevents that from happening. - Prolactin receptor sites on the alveoli allow prolactin from the anterior pituitary gland to initial the alveoli to secrete milk proteins. And so colostrum is produced from as early as embryonic stage week 16. - Hence by mid-pregnancy the breasts are capable of making milk but they don't release it; except for occasional leakages. the placental hormone progesterone acts as an inhibitor of prolactin release. Keeping milk production in check. - Nonetheless Lactogenesis I is about the endocrine control of secretory cellular activity and their subsequent milk production. - Prolactin is kept in check by prolactin-inhibiting factor

Quadrants and borders of the breast

- Lies above the 2nd and 6th rib - Pectoralis Major posteriorly - Sternum medially - Anterior axillary line laterally Quadrants: UOQ, UIQ, LOQ, LIQ

After birth

- Part of birth is the delivery of the placenta and this significantly reduces the amount of progesterone over a period of 2-3 days and this reduction initiates Lactogenesis II = the onset of copious milk secretion as prolactin is increased due to the reduction of progesterone - And also importantly the stimulation of the nipple by the baby suckling leads to neuron transmitted to the mother's hypothalamus. - That in turn sends a 'off' signal to the prolactin inhibiting factor which in turn leads to increased prolactin (and subsequent increase in production of milk). - It also sends an 'on' signal to oxytocin and the increase in oxytocin levels leads to the contraction of the myoepithelial cells. - So the production of milk and the ejection of milk occurs and this is known as the let down reflex. - Plasma protein levels increase sharply after placental delivery and rise and fall with frequency, intensity and duration of nipple stimulation. - However the alveoli cells need to be receptive to prolactin. - Frequent feeding in early lactation stimulates development of prolactin reception sites - The theory is that the controlling factor in breast milk production is the number of prolactin receptor sites and not the amount of prolactin in circulating blood. - Mothers who do not breast feed their babies be 'protected' by this mechanism - likely to be in place for mothers whose baby dies at birth. - Lactation moves from being endocrine controlled to autocrine controlled. - Milk contains a whey protein known as feedback inhibitor of lactation (FIL) the more milk there is in the alveoli cell the stronger the signal to inhibit milk production. - When the baby suckles at the breast and removes milk it also removes the inhibitor, FIL, and milk production recommences. FIL means that the milk production is baby led. - The amount of milk the baby strips the breast (equates how much the baby needs) will determine how much milk is replaced for next feed. - Prolactin is required to enable milk secretion but is no longer controlling the amount of milk being produced.

To be aware of...

- The hypothalamic stimulation from breastfeeding disrupts the normal ovulatory cycle - Although not a reliabe form of birth control it does increase space between children - Soon after delivery mother produces more and more milk and during the first week the baby's stomach grows from the size of a blueberry to a walnut - Normal to see a dip in baby's body weight but should be <7% - By second week of life the weight should be completely regained - Newborns feed a lot, during first day they're typically exhausted but afterwards they feed every 1-2 hours (3 hr max) - Allowing the baby to frequently empty the breast stimulates the glandular tissue to make even more milk - After a feeding the breasts should feel soft and empty, and the baby more relaxed - As baby grows older and stops feeding, the glandular tissue involutes and breasts stop producing milk - A healthy and balanced diet is needed to make high quality breast milk - Although food can flavor milk, no particular foods should be avoided while breastfeeding

Describe mammogenesis

- The mammary gland is the only organ not fully developed at birth. - In females the development of the breast to be fully functional and produce breast milk to nurture a new born baby occurs in stages. - This is termed mammogenesis - Initially in utero up to week 16 of the embryonic stage specialised cells differentiate into the nipple and the areola. - The basic anatomic structure of the lactiferous ducts and branches occur and have openings at the nipple. - The lumen of the ducts at the nipple end is allowed to close because of the smooth muscle of the nipple. - At puberty and the onset of menses these functional parts begin to develop, ducts divide and grow and the terminal end buds form and develop into alveoli

Problems with breastfeeding

Biggest impediments of establishing a good supply is - introduction of formula - not breastfeeding regularly Its normal in the first few weeks to have nipple sensitivity and discomfort but usually diminishes after first few suckles Occasionally can have nipple cracking, treated with topical creams and ointment Also tenderness from blocked milk ducts; which is helped by warmth and continued feeding

Cancer and lymph drainage

Cancer cells tend to spread along lymph passages • Typical spread is superiorly/laterally to axillary lymph nodes • More than 75% of drainage via axillary lymph nodes • Most remaining drainage is medially to parasternal nodes • Lymph can also drain to opposite side 3 Levels of surgical dissections relative to pectoralis minor in terms of breast cancer spread - Level I = below (lateral to) pec. minor - Level II = deep to pec. minor - Level III = above (medial to) pec. minor

Idk

Caused by trauma to nipple, poor attachment - think of the petrol pump nozzle not fitting in the car and so inefficient in filling up the tank - same principle - the baby needs to be able to strip the breast - all of the breast - efficiently. Any blocked ducts from tight bras, or mother holding their breast tissue out of the way of the baby's nose etc can lead to milk not draining and then getting infection. Check for pyrexia and tachycardia - infection v engorgement. Flu like symptoms if breast milk returns to blood stream so not necessarily infection. Must continue to drain milk - either express - (hand is more gentle that a pump) or keep feeding. If feeding is stopped the problem is exacerbated.

Breast milk contents

Initially after birth the breasts make colostrum - Yellowish fluid high in immune cells & antibodies but low in fat - Coats the baby's GI tract and has a laxative effect to help the passage of meconium - Few days after delivery the breasts start producing milk; higher fat content - Amount of fat in milk can actually vary during a feeding session - When milk is sitting in the breast fat globules stick to alveolar walls rather than moving to the lactiferous ducts - So when a baby starts feeding it drinks the milk in the ducts first which has a relatively low fat content - The process of feeding increases milk flow and the fat globules get swept into the lactiferous ducts so fat content increases throughout the session - Breast milk also contains lactose, vitamins, micronutrients and proteins like casein and maternal antibodies (most importantly segretory IgA that supplemetns GI immune system) - Amount of vitamin D is insufficient in the milk mainly cuz of the modern newborn that stays inside so supplemental vitamin D is often needed

Supply to the breast

Nerves: Anterior and lateral cutaneous branches of the 4th - 6th intercostal nerves Medially: Internal thoracic + perforating branches Laterally: Lateral thoracic and thoracoacromial branches - originate from the axillary artery. Posterior intercostals Venous: Axillary and internal thoracic veins

Small breast size implication?

Size is not related to functional capacity but is related to ability to store. So maybe feed more frequently but shorter duration but overall will be able to give the same amount within a 24 hour period.

Skin to skin

Skin to skin mediates increase prolactin surges and early feeding initiates prolactin receptor sites.

Stages of breast development

Stage 1 (Preadolescent) only the tip of the nipple is raised Stage 2 Buds appear, breast and nipple raised, and the areola (dark area of skin that surrounds the nipple) enlarges Stage 3 Breasts are slightly larger with glandular breast tissue present Stage 4 The areola and nipple become raised and form a second mound above the rest of the breast Stage 5 Mature adult breast; the breast becomes rounded and only the nipple is raised

HIV and breastfeeding

The HIV virus can cross into the breastmilk so women are not encouraged to breast feed in developed countries - a different approach in underdeveloped countries where safe bottle feeding is more risky and reduces the nature antibodies present in breast milk. This can be seen as a child protection issue but only regarding breast feeding not in reference to a mother with HIV.

Label 1

just know the paragraph at the bottom

Lymphatic drainage of the breast

• As with any other organs lymph drainage follows the pathway of it blood supply blood • Lymph passes from the nipple, areola and lobules of the gland to the sub-areolar lymphatic plexus (of Sappey) • From there travels: - Along tributaries of the axillary vessels to axillary lymph nodes (~75%) - Along tributaries of the internal thoracic and intercostal perforating vessels to internal thoracic chain of lymph nodes Lymph drains from breast towards a series of nodes: - Lat. drainage is via 5 groups of axillary nodes (~20-30 nodes) - Superior drainage is via 1 group of interpectoral nodes - Medial drainage is via 1 group of parasternal nodes to the thoracic ducts • Ultimate drainage is via subclavian lymphatic trunk • A small amount may drain inferiorly to the groin

Changes in the breast (overview)

• Breast development - distinct stages throughout a woman's life, - First before birth = milk lines - Puberty = mammary glands are influence by hormonal changes - During the childbearing years. • Changes also occur to the breasts during the menstrual cycle and when a woman reaches menopause • Puberty - ovaries start to secrete estrogen, fat in the connective tissue accumulate causing the breasts to enlarge and the duct system begins to grow. • Once ovulation and menstruation begin - formation of secretory glands, duct system continues to grow and mature, development of many glands and lobules. • During the menstrual cycle and pregnancy branching of the lactiferous ducts occur. • Although the mammary glands are prepared for secretion by mid-pregnancy, they do not produce milk until shortly after birth - initially colostrum. • Involution or shrinkage of the milk ducts is the final major change that occurs within the breast tissue in later life - the onset of menopause

Anatomy of the breast

• Female breasts (mammary glands) - modified sweat glands - extends from the lateral boarder of sternum to mid-axillary line (2nd - 6th rib). • Lies in superficial fascia anterior to deep fascia of pectoralis major and serratus anterior, but often has an axillary tail (of Spence) = may be present all the time or may come in menstrual cycle or pregnancy • Glandular tissue supported by fibrous tissue within a fatty matrix, with blood vessels, lymphatics and nerves • Glands are attached to skin via connective tissue • There are between 15 - 20 large lactiferous ducts that converge radially to open at the nipple. • Each of these main ducts drains one lobe of the mammary gland. Within a lobe, the ducts branch and drain the lobules of which it is composed. • The milk-producing alveoli (the alveolus) are arranged in grape-like clusters. • Between the lobules (15-20) the tissue of the breast contains many adipocytes • Within the fatty tissue particularly in the upper part of the breast some fibrous strands form septa that anchor the dermis of skin to deep fascia supporting the lobes and lobules of the breast - suspensory ligaments (of Cooper) • Cooper's ligaments may be contracted in cancer of the breast which produces a characteristic pitting or dimpling of the overlying skin "orange peel" • Retromammary space (bursa) - potential space of loose subcutaneous tissue plane - allow some movement of the fascia • Lactiferous ducts converge & drain on to the nipple, which is surrounded by the pigmented areola • The areola undergoes a more obvious and permanent darkening during the second month of the first pregnancy. • The areola is lubricated by conceals sebaceous glands - areolar glands of Montgomery • The nipple is composed of mostly circular smooth muscle fibres - compress the lactiferous ducts during lactation and erect the nipple in response to stimulation - e.g. suckling