Breast Anatomy

Basic Anatomy and some applied aspects are described in this PPT.
References
1) B.D.Chaurasia book of anatomy
2) Sabiston book of surgery
3) Wikipedia

1. Breast Anatomy Dr. Mayur Patel (M.S. General Surgeon) B.J. Medical college, Civil Hospital, Ahmedabad.

2. Introduction Latin word Breast = Mammary gland. Modified sweat gland. Accessory organ of female reproduction system.

3. Situation and extend Lies in superficial fascia of pectoral region. Extended Vertically - from 2 nd to 6 th ribs. Horizontally – lateral border of sternum to maxillary line Lies on deep fascia (pectoral fascia) and separated from fascia by retro mammary space. 2 nd RIB 6 th RIB Pectoral fascia Pectoralis minor Pectoralis Major Retro mammary space

4. Situation and extend

5. Situation and extend Lymphatics are present in retro mammary space. That is why in MRM we dissect the breast tissue with pectoral fascia.

6. Situation and extend Breast is divided in four quadrants Upper inner Upper outer Lower outer Lower inner Nipple areola complex should be mentioned separately while describing breast examination.

7. Situation and extend Upper lateral quadrant has lateral extension – known as axillary tail of Spence. It piers deep pectoral fascia – known as foramen of langer . It has direct communication with anterior group of axillary lymph nodes. That is why we need to remove axillary LN with breast tissue with connecting axillary tail in continuity .

8. Structure of breast It can be divided in 3 components Skin with nipple areola Parenchyma Stroma

9. Structure of breast Nipple A conical projection P resent just below the centre of the breast at the level of the fourth intercostal space 10 cm from the midline. The nipple is pierced by 15 to 20 lactiferous ducts. It contains circular and longitudinal smooth muscle fibres which can make the nipple stiff or flatten it, respectively. It has a few modified sweat and sebaceous glands.

10. Structure of breast Areola Pigmented skin surrounding Nipple. Rich in modified sebaceous glands, particularly at its outer margin. These become enlarged during pregnancy and lactation to form raised tubercles of Montgomery. Oily secretions of these glands lubricate the nipple and areola, and prevent them from cracking during lactation.

11. Structure of breast Areola Apart from sebaceous glands, the areola also contains some sweat glands, and accessory mammary glands. The skin of the areola and nipple is devoid of hair, and there is no fat subjacent to it. Below the areola lie lactiferous sinus where stored milk is seen.

12. Structure of breast Langer’ lines Circumareolar incision  Webster’s incision Submammary incision  Galliard Thomas incision In upper quadrants – Incision if away from NAC then it should be along the langer’s line But in lower quadrants – it should be radial to prevent NAC displacement downward.

13. Structure of breast Parenchyma It is a compound tubulo -alveolar gland which secretes milk. The gland consists of 15 to 20 lobes. Each lobe is a cluster of alveoli, and is drained by a lactiferous duct. The lactiferous ducts converge towards the nipple and open on it. Near its termination each duct has a dilatation called a lactiferous sinus

14. Structure of breast Alveolar epithelium cuboidal in the resting phase columnar during lactation. The smaller ducts columnar epithelium T he larger ducts two or more layers of cells the terminal parts of the lactiferous ducts by stratified squamous keratinised epithelium.

15. Structure of breast The passage of the milk from the alveoli into and along the ducts is facilitated by contraction of myoepitheliocytes , which are found around the alveoli and around the ducts, lying between the epithelium and the basement membrane.

16. Structure of breast Stroma Stroma forms the supporting framework of the gland. It is partly fibrous and partly fatty. There are fibrous bands that provide structural support and insert perpendicularly into the dermis, termed the suspensory ligaments of Cooper. That is why if involvement of cooper’s ligament  skin retraction

17. Blood supply The mammary gland is extremely vascular. Internal thoracic artery, a branch of the subclavian artery, through its perforating branches. The lateral thoracic, superior thoracic and acromiothoracic ( thoracoacromial ) branches of the axillary artery. Lateral branches of the posterior intercostal arteries.

18. Blood supply The mammary gland is extremely vascular. Internal thoracic artery, a branch of the subclavian artery, through its perforating branches. The lateral thoracic, superior thoracic and acromiothoracic ( thoracoacromial ) branches of the axillary artery. Lateral branches of the posterior intercostal arteries.

19. Blood supply First Part – Origin to Medial border of scalene anterior Vertebral artery Internal thoracic artery  Continue as superior epigastric artery. Thyrocervical trunk Second Part – Behind scalene anterior Costocervical trunk Third Part – Lateral border of scalene anterior and medial border of first rib. Dorsal scapular artery. Subclavian artery

20. Blood supply

21. Blood supply First Part – Superior to the pectoralis minor Superior thoracic artery (Supreme thoracic artery) Second Part – Posterior to the pectoralis minor Thoraco-acromian artery Lateral thoracic artery Third Part – Inferior to the pectoralis minor. Subscapular artery Anterior circumflex humoral artery Posterior circumflex humoral artery Axillary artery

22. Blood supply

23. Lymphatic drainage Specialized lymphatic channels collect under the nipple and areola and form Sappey’s plexus. 75% axillary nodes 20% internal mammary nodes 5% posterior intercostal nodes

24. Lymphatic drainage

25. Lymphatic drainage The lymphatics from the deep surface of the breast pass through the pectoralis major muscle and the clavipectoral fascia to reach the apical nodes, and also to the internal mammary nodes.

26. Lymphatic drainage Lymphatics from the lower and inner quadrants of the breast may communicate with the sub diaphragmatic and sub peritoneal lymph plexuses after crossing the costal margin and then piercing the anterior abdominal wall through the upper part of the linea alba.

27. Lymphatic drainage T hree anatomic levels defined by their relationship to the pectoralis minor muscle . Level I nodes are located lateral to the lateral border of the pectoralis minor muscle. Level II nodes are located posterior to the pectoralis minor muscle. Level III nodes include the sub clavicular nodes medial to the pectoralis minor muscle.

28. Lymphatic drainage The anterior (pectoral) group lie along the lateral thoracic vessels. T he posterior (scapular) group lie along the subscapular vessels. T he lateral group lie along the upper part of the numerus, medial to the axillary vein. T he central group lie in the fat of the upper axilla. The apical ( infraclaaicular ) group lie deep to the clavipectoral fascia, along the axillary vessels.

29. Lymphatic drainage Lymph nodes in the space between the pectoralis major and minor muscles are termed the interpectoral group, or Rotter’s nodes.