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Morphology of the mammary gland

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Objectives: …

Objectives:
Describe the location of the breast in relation to fascial layers
Identify the extent of the base of the breast
Define the reteromammary space
Identify the axillary tail and its significance
Understand the differences in size and colour of the areola; contractility of the nipple; Montgomery’s glands.
Describe the lobes of the breast and the clinical significance of the suspensory ligaments.
Describe the histological changes of the mammary gland during different phases: before puberty, inactive gland, during menstruation, active phase, and menopause.
Identify myoepithelial cells and their functional significance.
Understand the role of merocrine and apocrine secretion in the production of milk.
Describe mammary line and its congenital anomalies: polymastia, polylethelia, inverted nipple.
Identify the features of the pregnant woman’s breast
Understand the features of structural involvement in breast cancer
Breast features in mammography.
Incising for and positioning of a breast implant.
Describe the male breast and gynaecomastia.
Locate the arterial blood supply and venous drainage of the breast.
Describe the nerve supply and reflex secretion of milk
Thorough description of the lymphatic drainage of the breast and axillary lymph nodes
Applied anatomy of breast cancer metastasis, peau d’orange, and lympodema of the upper limb.
Surgical anatomy of mastectomy and paralysis of the long thoracic nerve.

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  • 1. Morphology of the Mammary Gland Dr. Akram Jaffar, Ph.D.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 2. References and further reading  Moore KL & Dalley AF (2006): Clinically Orientated Anatomy. 5th Ed. Lippincott, Williams & Wilkins. Philadelphia. pp: 105-111  Snell RS (2007): Clinical anatomy by systems. Lippincott. Philadelphia. pp:90-94  Eroschenko VP (2005): diFiore’s Atlas of Histology with Functional correlations. 10th ed. Lippincott Williams & Wilkins. Baltimore  Sadler TW (2006): Langman’s Medical Embryology. 10th ed. Lippincott Williams & Wilkins. Baltimore. pp:337-338© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 3. Objectives  Describe the location of the breast in relation to fascial layers  Identify the extent of the base of the breast  Define the reteromammary space  Identify the axillary tail and its significance  Understand the differences in size and colour of the areola; contractility of the nipple; Montgomery’s glands.  Describe the lobes of the breast and the clinical significance of the suspensory ligaments.  Describe the histological changes of the mammary gland during different phases: before puberty, inactive gland, during menstruation, active phase, and menopause.  Identify myoepithelial cells and their functional significance.  Understand the role of merocrine and apocrine secretion in the production of milk.  Describe mammary line and its congenital anomalies: polymastia, polylethelia, inverted nipple.  Identify the features of the pregnant woman’s breast  Understand the features of structural involvement in breast cancer  Breast features in mammography.  Incising for and positioning of a breast implant.  Describe the male breast and gynaecomastia.  Locate the arterial blood supply and venous drainage of the breast.  Describe the nerve supply and reflex secretion of milk  Thorough description of the lymphatic drainage of the breast and axillary lymph nodes  Applied anatomy of breast cancer metastasis, peau d’orange, and lympodema of the upper limb.© Dr. Akram Jaffar  Surgical anatomy of mastectomy and paralysis of the long thoracic nerve. © Dr. Akram Jaffar
  • 4. The female breast Superficial fascia  Skin gland capable of secreting milk.  Being a skin gland, the breast is situated in the superficial fascia and has NO capsule. Deep fascia Pectoralis Major m.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 5. Base of the breast Pectoralis  The breast can be easily Major m. separated from the deep fascia covering pectoralis major, serratus Serratus anterior and external oblique Anterior m. muscles on the anterior thoracic wall. External Oblique m.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 6. Retromammary space  A loose connective tissue plane or potential space  Between the breast and the deep pectoral fascia  Allows the breast some degree of movement.  When breast cancer invades this space, the breast elevates when the pectoralis major muscle contracts. To observe this movement, the doctor asks the patient to put her hands on her hips and press to tense her pectoral muscles.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 7. Base of the breast  In spite of differences in the size and shape of the breasts, the size of the base of the breast is fairly constant.  The base of the breast extends  from the 2nd to the 6th rib in the midclavicular line  from the edge of the sternum to the mid- axillary line.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 8. Axillary tail Pectoralis  Extends upwards and laterally along the inferior Major m. border of pectoralis major muscle.  Contains a large amount of glandular tissue, and a great percentage of breast tumors occur there. tail© Dr. Akram Jaffar Percent distribution of breast tissue Percent distribution of breast tumor © Dr. Akram Jaffar
  • 9. Axillary tail  This breast tail (of Spence) enters a hiatus (of Langer) in the deep fascia of the medial axillary wall.  The only breast tissue found beneath the deep fascia.  May be visible as definite mass simulating an axillary tumor© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 10. The areola  Hyperpigmented area of skin surrounding the nipple.  Contains modified sebaceous glands called areolar glands of Montgomery  The areolar glands enlarge during pregnancy and secrete an oily substance that protects the areola and nipple© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 11. Size and color of the areola  Variable in size and color.  At puberty, the areola enlarges and become more pigmented.  The depth of color depends on the woman’s skin color. White nulliparous  pink in white nulliparous woman Negro  dark brown in Negroes  During pregnancy, the areola enlarges and becomes deep brown to black.  The color diminishes after pregnancy but never returns to the original pink color. Pregnant Increasing age© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 12. The areola  Small collection of smooth muscle located at the base of the nipple may cause erection of the nipple during nursing or sexual arousal. Relaxed areola© Dr. Akram Jaffar Contracted areola © Dr. Akram Jaffar
  • 13. Breast lobes gland lobe  There are 15-20 lobes of duct glandular tissue.  The lobes are separated by fibrous tissue septa.  Each lobe is drained by a lactiferous duct. Fibrous  Lactiferous ducts extend from septum the nipple in a radial manner.  Under the areola, each duct has a dilated portion called sinus lactiferous sinus in which milk accumulates during lactation.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 14. Suspensory ligaments  Fibrous tissue septa that extend from the deep fascia to the skin are called the suspensory ligaments of the breast (ligaments of Cooper).  Maintain the breast form in the upright posture.  Less effective when a person lies on her back© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 15. Suspensory ligaments  Malignant infiltration of the suspensory ligaments causes their shortening and invagination (dimpling) of the overlying skin Deep fascia Suspensory ligament© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 16. Suspensory ligaments  Abscess in the breast is preferably opened by a radial incision to avoid cutting across a number of lactiferous ducts (being radially arranged) and to prevent spread of infection from one lobe to another across the borders (suspensory ligaments).© Dr. Akram Jaffar Breast abscess Breast abscess drainage Breast lobes © Dr. Akram Jaffar
  • 17. Histology of the mammary gland  Compound alveolar gland© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 18. Histology of the inactive gland  Abundant connective tissue Ducts  The sparse glandular lobule component consists chiefly Dense CT of ducts.  Ducts are surrounded by a loose connective tissue Loose CT containing lymphocytes, plasma cells and fibroblasts.  The ducts and surrounding loose connective tissue constitute a lobule.  Beyond a lobule, the connective tissue is more dense Adipose tissue  The dense connective© Dr. Akram Jaffar tissue contains aggregates of adipocytes. © Dr. Akram Jaffar
  • 19. Histology of the tubular portion  The lactiferous ducts are lined with stratified squamous epithelium near their openings at the nipple.  In the lactiferous sinus, the lining is stratified cuboidal.  The remainder of the duct system is lined by a single layer of columnar or cuboidal cells. Columnar - cuboidal Stratified cuboidal© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 20. Myoepithelial cells  Cells of ectodermal origin  Lie within the epithelium between the surface epithelial cells and the basal lamina.  Are present in the ductal and secretory portion of the gland. Loose CT cells© Dr. Akram Jaffar Myoepithelial cell Basal lamina © Dr. Akram Jaffar
  • 21. Histological changes  Changes during the menstrual cycle  Early in the cycle, the ducts appear as cords with little or no lumen.  Under estrogen stimulation, at about the time of ovulation, the secretory cells increase in height, lumina appear in the ducts as small amounts of secretions accumulate, and fluid accumulates in the connective tissue.  Changes in preparation for lactation:  Decrease in the amount of connective tissue and adipose tissue.  Plasma cells, lymphocytes, and eosinophils infiltrate the fibrous component of the connective tissue.  Development of glandular tissue: cells proliferate by mitotic division, the ducts branch and alveoli begin to develop.  In the later stages of pregnancy, alveolar development becomes more prominent. The actual proliferation of the stromal cells declines, and subsequent enlargement of the breast occurs through hypertrophy of the secretory cells and accumulation of secretory product in the alveoli.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 22. Histological changes  Changes after menopause.  Degeneration of glandular tissue but some ducts may remain  Degeneration of connective tissue: decrease in the number of fibroblasts and collagen fibers, and loss of elastic fibers  pendulous breast.  During puberty  Enlargement mainly from increased fat deposition and partly from glandular development© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 23. Histology of the active (lactating) gland  Individual lobules are separated by narrow dense connective tissue septa  The connective tissue within a lobule is loose connective tissue that is now containing more lymphocytes and plasma cells.  The ducts and alveoli are well developed, secretory products may be seen in the lumen  Alveoli show irregular branching pattern Branching alveoli Glandular tissue Secretory product Dense CT Plasma cell© Dr. Akram Jaffar lymphocyte © Dr. Akram Jaffar
  • 24. Method of secretion  The protein component of the milk.  Merocrine secretion: secretory vesicles coalesce with the membrane on the apical surface to release the product:  The lipid component of the milk  Apocrine secretion. lipid droplets pass to the apical region of the cell. The droplets are invested with an envelope of plasma membrane and a thin layer of cytoplasm as they are released into the lumen of the acini.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 25. Embryology  The first indication of mammary glands is a band-like thickening of epidermis, the mammary (milk) line.  The milk line extends from the upper thigh superiorly to the axilla.  The major part disappears.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 26. Embryology  In the thoracic region, a small portion penetrates the mesenchyme, forms sprouts which give rise to a small solid bud.  The sprouts are canalized  lactiferous ducts  small ducts and alveoli.  Initially, the ducts open into a small epithelial pit. The pit proliferates into a nipple after birth© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 27. Comparative anatomy  In many mammals (cats, dogs, etc.), the milk line persists as fully formed mammary glands, but in humans only one breast on each side develops.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 28. Polythelia (supernumerary nipple)  Accessory nipples are formed due to the persistence of mammary line.  May develop anywhere along the original line but usually in the axilla.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 29. Polymastia  Occasionally, a supernumerary (i.e. extra) breast may develop along this milk line.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 30. Inverted nipple  In many women, the original epithelial pit fail to evert.  Retraction of the nipple, if a new occurrence should have a high index of suspicion for a malignancy.  When congenitally retracted, this should not be a cause for concern except when preparing to breast-feed. This can often be assisted by nipple shields, which revert the retracted nipple. Congenital retraction© Dr. Akram Jaffar Retracted nipple + tumor © Dr. Akram Jaffar
  • 31. Features of a pregnant woman’s breast  The whole breast is enlarged and the axillary tail is noticeable  Dilated veins can be seen over the breast skin  The nipple and areola are deeply pigmented  Areolar glands increase in number and size© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 32. External features of breast cancer© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 33. Mammography  A low-powered x-ray technique that gives a picture of the internal structure of the breast.  May help in the diagnosis of breast problems including cancer Mammogram© Dr. Akram Jaffar Technique © Dr. Akram Jaffar
  • 34. Breast implantation  A surgical procedure for enlarging the breast.  Breast-shaped sacks made of a silicone outer shell and filled with silicone gel or saline are used.  The incision is made through the axilla, under the breast, or around the areola to create the most inconspicuous scars.  The implant is placed between the breast tissue and underlying pectoralis major muscle, or under the pectoralis major muscle. Position of the implant© Dr. Akram Jaffar Sites for the incision © Dr. Akram Jaffar
  • 35. The male breast  During embryologic development, growth and development of breast tissue occur in both sexes.  In males, little additional development of the mammary glands occurs in postnatal life, and the glands remain rudimentary.  Has similar structure to immature female’s breast.  The nipples are small.  The breast tissue consists of a system of ducts embedded in connective tissue.  The breast tissue does not extend beyond the margin of the areola  May be affected by breast cancer© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 36. Gynecomastia  Activation and hypertrophy of the breast tissue in men.  It can occur frequently in young men (pubertal hypertrophy) and in older men.  It can also be caused by numerous medications and hormones© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 37. Innervation  Anterior and lateral cutaneous branches from the second to sixth intercostal nerves: cutaneous and sympathetic innervation (blood vessels and smooth muscle of skin and nipple).  The secretory function is primarily under hormonal control, but afferent impulses associated with suckling are involved in the reflex secretion of prolactin and oxytocin.  Suckling during breast-feeding initiates sensory impulses from receptors in the nipple to the hypothalamus  prolactin release from the adenohypophysis.  The sensory impulses also cause the release of oxytocin in the neurohypophysis. Oxytocin stimulates the myoepithelial cells that surround the base of the alveolar secretory cells and the base of the cells in the larger ducts, causing them to contract and eject the milk from the alveoli and the ducts.  The milk is secreted into – not sucked from the gland by – the baby’s mouth.  In the absence of suckling, secretion of milk ceases, and the mammary glands begin to regress. The glandular tissue then returns to an inactive condition.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 38. Arterial supply  Internal thoracic artery via perforating Internal Thoracic a. (mammary) branches that perforate pectoralis major muscle.  At the 2nd-4th intercostal spaces these perforating branches are particularly large.  The internal thoracic branches supply most of the blood to the breast. Pectoralis Major m. Perforating a.© Dr. Akram Jaffar Internal Thoracic a. Perforating a. © Dr. Akram Jaffar
  • 39. Arterial supply Superior Thoracic a.  Axillary artery: Thoraco-acromial a.  Lateral thoracic artery.  Pectoral branch of the thoraco- acromial artery  Suprior thoracic artery Lateral thoracic a.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 40. Arterial supply  Posterior intercostal arteries via lateral perforating branches Post. intercostal a. Perforating a.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 41. Venous drainage  The venous drainage is to the veins corresponding the arteries Internal Thoracic v.  The chief venous drainage is towards the axilla  The intercostal veins communicate posteriorly with the vertebral venous plexus, To axillary v. which enters the azygos veins and eventually the superior vena cava. By this pathway SVC metastasis may travel to the Azygos v. skeleton and central nervous system  venous spread of breast cancer may reach the liver through porto-caval anastomoses Post. Intercostal v. Internal vertebral Venous plexus© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 42. Lymphatic drainage Axillary LNs  Axillary vessels to axillary lymph nodes which constitute the major drainage area for the breast.  Internal thoracic vessels to parasternal lymph nodes located along these vessels.  There is a tendency for the lateral part of the breast to drain towards the axilla and the medial part to the parasternal group.  Most carcinomas of the breast occur in the upper lateral quadrant and thus Parasternal LNs undergo metastasis to axillary lymph nodes© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 43. Lymphatic drainage  Obstruction of the usual lymphatic pathway by malignant cells will cause cancer cells to pass along uncommon channels:  Infraclavicular lymph nodes  Contralateral breast  Anterior abdominal wall© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 44. Peau d’orange  Blockage of the lymph drainage of the skin overlying the tumor causes edema  The skin is thickened and prominent between dimpled pores.  The skin looks like an orange peel (peau d’orange).© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 45. Axillary lymph nodes  Drain not only the breast but also  The pectoral region  Upper part of the abdominal wall  Upper part of the back  The upper limb© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 46. Axillary lymph nodes apical gp Central gp Pectoralis Minor m. Axillary v.  Axillary lymph nodes are arranged in five groups  Anterior or pectoral group lying deep to pectoralis major along the inferior border of pectoralis minor muscle: drain most of the lymph of the breast  Posterior or subscapular group, lie in front of subscapularis on the posterior wall of the axilla .  Lateral group lying along the axillary vein  Central group lying in the axillary Anterior gp. fat  Apical group lying behind the posterior gp.© Dr. Akram Jaffar clavicle at the apex of the axilla lateral gp. © Dr. Akram Jaffar
  • 47. Examination of axillary lymph nodes Posterior group Central group© Dr. Akram Jaffar Pectoral group © Dr. Akram Jaffar
  • 48. Lymphoedema  The axillary lymph nodes are often removed or irradiated during treatment of breast cancer, in such a case lymphoedema in the upper limb follows because axillary lymph nodes drain the upper limb in addition to the breast.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 49. Surgical anatomy of mastectomy  Three types of mastectomy:  Radical mastectomy: Removal of the breast, axillary lymph nodes, pectoralis major and minor  Modified radical mastectomy: Removal of the breast and axillary lymph nodes  Simple mastectomy: Removal of the breast only.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 50. Triangular bed of radical mastectomy Pectoralis minor m. Axillary v. Subscapular nn Long thoracic n. Thoracodorsal n. Serratus Latissimus Ant. m. Dorsi m. Subscapularis m. Pectoralis Major m.© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 51. Long thoracic nerve  seen in the pectoral region on  a branch of brachial plexus C5,6, & 7. It is the surface of serratus anterior also called the nerve of Bell just behind the mid axillary line, supplying the muscle  May be injured during radical mastectomy© Dr. Akram Jaffar © Dr. Akram Jaffar
  • 52. Long thoracic nerve injury Winged scapula  When the serratus anterior is paralyzed, the medial border of the scapula appears to be projecting backwards giving the appearance of a wing when the patient presses against a wall 3 2 trapezius deltoid 1 supraspinatus  In addition, the patient is unable to raise his/her arm above the head owing to© Dr. Akram Jaffar inability to rotate the scapula during abduction of the arms above a right angle 3 3 trapezius serratus anterior © Dr. Akram Jaffar