Pectoral region

Anatomy of upper Extremity

1. Pectoral Region Dr.Heta Patel(PT) Assistant Professor ARIP cHARUSAT

2. What to learn? Introduction Surface landmarks Superficial fascia Deep fascia Muscles of pectoral region

3. Introduction Location: Front of chest Essential consist of structure which connects the upper limb to the anterolateral chest wall i.e. bones and muscles Additionally Mammary gland

4. Surface landmarks Clavicle Jugular notch Sternal angle Epigastria fossa Nipple

5. Midclavicular Infraclavicular fossa Coracoid process Acromion Deltoid Midaxillary line

6. Superficial fascia Band Contains: moderate amount of fat, mammary gland, fibrous septa Contents Cutaneous nerves Cutaneous vessels The platysma The breast

7. Cutaneous Nerves Branches of the cervical plexus (C3, C4 ): (medial , intermediate and lateral supraclavicular nerves) skin over the upper half of the deltoid and from the clavicle down to the second rib. The anterior and lateral cutaneous branches of the second to sixth intercostal nerves : skin below the level of the second rib. The intercostobrachial nerve T2 : skin of the floor of the axilla and the upper half of the medial side of the arm .

8. Pulled away: The area supplied by spinal nerves C3 and C4 directly meets the area supplied by spinal nerves T2 and T3. This is because of the fact that the intervening nerves (C5, C6, C7, C8 and T1) have been 'pulled away' to supply the upper limb .

9. Cutaneous Vessels The cutaneous vessels are very small. The anterior cutaneous nerves are accompanied by the perforating branches of the internal thoracic artery . The second, third and fourth of these branches are large in females for supplying the breast. The lateral cutaneous nerves are accompanied by the lateral cutaneous branches of the posterior intercostals arteries .

10. The Platysma T hin , broad sheet of subcutaneous muscle. Muscle of face S upplied by the facial nerve. When the angle of the mouth is pulled down, the muscle contracts and wrinkles the skin of the neck. The platysma may protect the external jugular vein (which underlies the muscle) from external pressure.

11. The Breast

12. Modified sweat gland- modified apocrine gland Made up of 15–20 lobules of glandular tissue embedded in fat. Fat accounts for its smooth contour and most of its bulk. These lobules are separated by fibrous septa running from the subcutaneous tissues to the fascia of the chest wall (the ligaments of Cooper/ Astley Cooper fibers/ suspensory ligaments) Between the capsule and the fascia over pectoralis major is the loose connective tissue of the retromammary space.

13. Each lobule drains by its lactiferous duct on to the nipple, which is surrounded by the pigmented areola. This area is lubricated by the areolar glands of Montgomery large, modified sebaceous glands →may form sebaceous cysts → may infected.

14. Surface anatomy

15. Naming the quadrants for the purpose of describing a lump Or Upper medial quadrant Upper lateral quadrant Lower medial quadrant Lower lateral quadrant

16. Position & extent    2/3 rests on pectoralis major , 1/3 on serratus anterior , while its lower medial edge just overlaps the upper part of the rectus sheath.

17. Cross section

18. Blood supply

19. Axillary artery → Lateral thoracic ( mainly) Acromiothoracic branches. Internal thoracic (internal mammary) artery →perforating branches; these pierce the 1 st – 4 th intercostal spaces, then traverse pectoralis major to reach the breast along its medial edge. The 1 st & 2 nd perforators are the largest of these branches. Intercostal arteries → lateral perforating branches- relatively unimportant source.

20. Venous drainage

21. Venous drainage Sub areolar venous plexus Posterior intercostal veins communicate with internal vertebral venous plexus veins - therefore cancers can spread to vertebra- may cause back pain

22. Lymphatic drainage

23. Follows the pathway of its blood supply along tributaries of the axillary vessels → axillary lymph nodes; internal thoracic vessels → piercing pectoralis major → to traverse each intercostal space → to lymph nodes along the internal mammary chain; these also receive lymphatics penetrating along the lateral perfora ting branches of the intercostal vessels.

24. A subareolar plexus of lymphatics below the nipple (the plexus of Sappey) 75% → axillary 15% → internal mammary Upper → can go to supraclavicular Lower 2 quadrants can go to subdiapragmatic or abdominal nodes

25. Dermatomal supply

26. Development and structure Begins to develop as early as the 4 th 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 .

27. Lobule formation occurs only in the female breast & does so after puberty . Each lactiferous duct is connected to a tree- like system of ducts and lobules, intermingled & enclosed by connective tissue to form a lobe of the gland.

28. The resting (non-lactating) breast, however consists mostly of fibrous & fatty tissue; variations in size are due to variations in fat content , not glandular tissue which is very sparse .

29. During pregnancy alveoli bud off from the smaller ducts & the organ usually enlarges significantly, & more so in preparation for lactation. When lactation ceases there is involution of secretory tissue. After menopause progressive atrophy of lobes & ducts takes place.

30. The male breast Resembles the rudimentary female breast has NO lobules or alveoli. The small nipple and areola lie over the 4 th intercostal space .

31. Clinical anatomy Amastia (Absence of breast) Polymastia (Supernumerary breasts) Athelia (Absence of nipple) Polythelia (Supernumerary nipples) Gynaecomastia (in Klinefelter’s syndrome ) Breast cancer Breast abscess

32. Amastia of right breast P ol y mastia Polythelia Nipple retraction A t helia Gynaecomas t ia

33. Radiological investigation : Mammography

34. MUSCLES OF THE PECRORAL REGION 1. Pectoralis major 2. Pectoralis minor 3. subclavius 4. Serratus anterior

35. Pectoralis major Origin: Clavicular head; from the front of the medial third of the clavicle Sternocostal head; from the anterior aspect of the sternum and the upper six costal cartilages Insertion: Lateral lip of bicipital groove of the humerus Action: 1. Adduction and medial rotation of the arm 2. Flexion of the arm (clavicular portion) Nerve supply Lateral pectoral nerve, C5, 6, 7 Medial pectoral nerve, C8, T1

36. Pectoralis minor Origin: 3 rd , 4 th and 5 th ribs near their cartilage. Insertion: Medial aspect of coracoid process of the scapula Action: Depresses point of shoulder; if the scapula is fixed, it elevates the ribs of origin Nerve supply: medial pectoral nerve, C8,T1

37. Subclavius muscle Origin: First costal cartilage Insertion: Lower surface of clavicle (subclavius groove) Action: Depresses the clavicle and steadies this bone during movements of the shoulder girdle Nerve supply: Nerve to the subclavius, from the roots of brachial plexus C5,6

38. Serratus anterior muscle Origin: From the outer surface of upper 8 ribs Insertion: costal aspect of medial border and inferior angle of scapula Action: Draws the scapula forward around the thoracic wall (protrusion); rotates scapula Nerve supply: long thoracic nerve, C5,6,7

39. Clavipectoral Fascia The clavipectoral fascia is a strong sheet of connective tissue that is attached above to the clavicle. Below, it splits to enclose the pectoralis minor then continues m u s c l e and do w n w ar d as the suspensory ligament of the axilla and joins the fascial floor of the armpit.

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