The Breast Anatomy PDF

The Breast Structure Blood Supply Lymphatics Human Body Structure & Function MED 512 Saba University School of Medicine David C. Hyland, Ph.D. Breast Position and Extent Modified sweat (apocrine) gland present in both...

The Breast Structure Blood Supply Lymphatics Human Body Structure & Function MED 512 Saba University School of Medicine David C. Hyland, Ph.D. Breast Position and Extent Modified sweat (apocrine) gland present in both sexes but is rudimentary in males Located in the superficial fascia of the pectoral region Extends Vertically from 2nd to 6th rib Loading… Horizontally from lateral sternal border to mid- - most breast axillary line cancar start Axillary tail of Spence here Normal extension of breast tissue in axilla The majority of breast cancers develop in the upper outer quadrant 3  Sternum Axillary tail Breast Position and Extent Axilla Fat Nipple 2/3 of the breast overlies pectoralis major Areola 1/3 of the breast overlies serratus anterior Serratus anterior --p Retromammary space – A loose connective tissue plane or potential space located between the breast and deep pectoral fascia; Allows some degree of movement on deep pectoral fascia 4  Breast Structure Skin Nipple – a conical projection from the center of the Stroma breast in a dark area of skin called the areola; contains Adipose 15-20 lactiferous ducts Loading… Areola – hyper-pigmented skin surrounding the nipple; the areola contains small modified sebaceous glands Parenchyma that lubricate the nipple during breastfeeding; these enlarge during pregnancy to form Montgomery’s tubercles Skin NAC – the nipple and areola together form the nipple areola complex or NAC 5  Breast Structure Parenchyma Lobes – consists of 15-20 lobes of glandular tissue separated by fibrous bands of connective tissue Lobules – each lobe is made up of lobules and at the end of each lobule are tiny “bulbs” called acini that - produce milk Lactiferous duct – each lobe is drained by a duct; all ducts converge at the nipple radially; it is in these ducts where most breast cancers begin Lactiferous sinus – each duct dilates before opening onto the surface 6  Breast Structure Stroma or suspensory - ligaments of Cooper Fibrous tissue Forms septae Divide parenchyma into 15-20 segments Anchor skin to deep fascia Involvement and retraction of these ligaments in breast cancer leads to fixity of gland & wrinkling of skin 7 Breast Development Begins to develop as early as the 4th week as a downgrowth from a thickened mammary ridge (milk line) of ectoderm along a line from the axilla to the inguinal region Supernumerary nipples or even glands proper may form at lower levels on this line Lobule formation occurs only in the female breast and does so after puberty 8 9 Lactation The resting (non-lactating) breast consists mostly of fibrous and fatty tissue; variations in size are due to variations in fat content, not glandular tissue, which is very sparse During pregnancy alveoli bud off from the smaller ducts and the organ usually enlarges significantly in preparation for lactation During lactation, the second to fourth perforating arteries increase in size to supply the mammary glands When lactation ceases there is involution of secretory tissue After menopause, progressive atrophy of lobes and ducts takes place 10 Male Breast Resembles the rudimentary female breast Has no lobules or alveoli The nipple and areola overlie the 4th intercostal space (ICS) Loading… Though rare, males can get breast cancer 11  * Arterial Supply of the Breast a Lymphatic Adomainta - Most arteries are distributed to the O anterior surface; the posterior surface is relatively avascular Branches of the following arteries supply the breast: Medial aspect Internal thoracic artery Lateral aspect Lateral thoracic artery Thoracoacromial artery Posterior intercostal arteries 12  Lateral Venous Drainage of the Breast e i natet b The majority of the breast drains to the axillary vein via the lateral thoracic v. Other veins involved include: Internal thoracic vein Posterior intercostal veins which communicate with the vertebral venous plexus (VVP) thus, cancer can spread to the vertebrae 13 Most duct upper o · Quadrates 14  B Co e e Lymphatics of the Breast * u baah Axillary lymph nodes are located within the axillary region of the upper limb; they are the largest group and drain approximately 75% of the breast Parasternal (internal mammary) lymph nodes are 4-5 in number; are located along the lateral border of the sternum accompanying the internal thoracic vessels and drain the inner quadrants of the breast; they ultimately drain into the bronchomediastinal lymphatic trunks Infraclavicular or deltopectoral lymph nodes are 2-3 in number; are located in the deltopectoral groove between the deltoid and pectoralis major mm.; drain the anterolateral aspect of the upper limb Supraclavicular lymph nodes are located in the fascia within the supraclavicular fossa just lateral to the clavicular head of sternocleidomastoid; it is the final common pathway of the lymphatic system as it joins the central venous system 15  Lymphatics of the Breast The axillary lymph nodes are located within the axillary region of the upper limb. The drainage areas for these nodes includes: upper limb, breast, and trunk above the level of the umbilicus There are approximately 20 to 30 (up to 40 have been noted) individual axillary lymph nodes which are divided into 5 groups: 1. Anterior or Pectoral 2. Posterior or Subscapular 3. Lateral or Humeral 4. Central 5. Apical or Subclavicular 16  Lymphatics of the Breast ↳ Needto ter memorize 1. Anterior or Pectoral (or external mammary) – 4-5 large nodes; lie along inferior border of col ect pectoralis minor m and lateral thoracic vessels; receives lymph from the anterolateral aspect of the abdominal wall superior to the level of the umbilicus and the lateral quadrants of the breast 2. Posterior or Subscapular – 6-7 nodes; lie along lateral border of subscapularis m; receives lymph from posterior neck and upper back 3. Lateral or Humeral – 4-6 nodes; posteromedial to axillary vein; receives lymph from the posteromedial aspect of the upper limb 4. Central – 3-4 nodes; lie at the base of the axilla; receives lymph from the previous three axillary groups 5. Apical or Subclavicular – 4-5 nodes; lie at lateral border of 1st rib; receives lymph from all other axillary groups plus directly drains the upper inner quadrant; also receives lymph from those lymphatic vessels accompanying the cephalic vein; drains into subclavian 17  S imp Hitting O ↳ 18 19 20 21 · 22  Lymphatics of the Breast Lymphatic drainage of breast originates from breast lobules and flows through intramammary nodes and channels into a network subareolar plexus, called Sappey’s plexus*. - From this plexus, lymphatic drainage takes place through three main routes that parallel 1. venous tributaries. Pathwas) Axillary or lateral pathway (primant 2. Internal mammary pathway 3. Retromammary pathway 23  Lymphatics of the Breast 1. Axillary or lateral pathway >75% of lymph from breast travels laterally to axillary nodes Drains all quadrants of the breast, with higher proportion of drainage from lateral quadrants, especially the upper outer quadrant Lateral quadrants (upper outer & lower outer) drain to pectoral (external mammary) lymph nodes 24  Lymphatics of the Breast 1. Internal mammary pathway