THORACIC WALL

2. THORACIC WALL MUSCLES, MAMMARY GLANDS, CROSS-SECTION

3. THORACIC WALL MUSCLES

4. Surface Muscles (Anterior) • Platysma • Pectoralis major • Pectoralis minor • Subclavius • Serratus anterior • Refer in syllabus: Table 1, pp 47-49 Figure 13, p 50

6. Surface Muscles (Posterior) • Latissimus dorsi • Trapezius • Rhomboideus major • Rhomboideus minor • Refer in syllabus: Table I; pp 47-9

7. Deltopectoral Triangle • Boundaries: Anterior border of the deltoid. Superior border of the pectoralis major. Middle third of the clavicle.

8. Deltopectoral Triangle • Contents: Cephalic vein. Deltopectoral lymph nodes. Deltoid branch of the thoracoacromial artery.

9. Clavipectoral Fascia • Invests subclavius and pectoralis minor. • Attached to clavicle and anterior thoracic wall. • Pierced by: Cephalic vein Thoracoacromial artery Lateral pectoral nerve • Become suspensory ligament of the axilla.

10. THORACIC WALL STRUCTURE (x.s.) Refer to Figure 15, p. 60 in syllabus as well as background material on pp 58-59.

12. MAMMARY GLAND

13. Mammary Glands • Modified sweat glands • 15-20 lobes • Lobes separated by fibrous septa • Lactiferous duct (1 per lobe) • Lactiferous sinus (ampulla): Dilation as duct enters nipple

14. Mammary Glands • Fibrous tela subcutanea: Connective tissue layer surrounding the entire gland. • Fatty tela subcutanea: Adipose tissue deep to fibrous layer. • Suspensory ligament of Cooper: Bundles of collagen fibers in dermis and hypodermis.

15. Mammary Glands • Breast extends from 2nd-3rd rib superiorly to 6th-7th costal cartilage inferiorly. • Extends from lateral border of sternum to beyond the anterior axillary fold.

16. Mammary Glands • Retromammary space: Space between the gland and the pectoralis major muscle. • Sinus mammarumis: Space between the two glands.

17. Mammary Gland Arteries • Anterior perforating arteries: From internal thoracic artery To medial part of gland • Medial mammary rami: From 2nd - 4th anterior perforating arteries To deep medial part of gland

18. Mammary Gland Arteries • Lateral mammary artery: From lateral thoracic artery. To inferior part of gland. • Lateral mammary rami: From lateral cutaneous branches of intercostal arteries. To lateral part of the gland.

19. Mammary Gland Veins • Superficial and deep venous plexuses drain into internal thoracic, lateral thoracic, and intercostal veins.

20. Mammary Gland Nerves • Lateral mammary nerve: T2-T6 • Anterior branch of lateral cutaneous branch of intercostal nerves. • Medial mammary nerve: T2-T6 • Lateral branch of anterior cutaneous branch of intercostal nerves.

21. Mammary Gland Lymphatics • Perilobular and interlobular lymphatic vessels: Into: • Subareolar plexus: Into: • Lateral lymphatic trunk: From lateral and superior gland • Medial lymphatic trunk: From medial and inferior gland

22. Mammary Gland Lymphatics • Lateral lymphatic trunk and Medial lymphatic trunk: Into: • Pectoral group of axillary lymph nodes: Into: • Subclavian lymphatic channels

23. Mammary Gland Lymphatics • Accessory lymphatic drainage: Periphery of gland drains into apical group of axillary nodes and follows thoracoacromial trunk. Circumareolar channels drain into sternal chain.

24. THORACIC WALL LYMPHATICS

25. Lymphatic Drainage • Subareolar plexus of nodes • Axillary lymph nodes: Receive from: Superficial tissues, skin, breast, extrinsic limb muscles. Include: Pectoral group Lateral group Apical group Subscapular group

26. Lymphatic Drainage • Infraclavicular nodes • Parasternal nodes • Abdominal nodes

27. MECHANICS OF RESPIRATION

28. Inspiration: “Bucket Handle” • Involves contraction of intercostal muscles • Results in raising of ribs • Results in an increase in the lateral dimensions of the thoracic cage.

29. Inspiration: “Pump Handle” • Results from raising of sternum • Results in increase in anteroposterior dimensions of thoracic cage

30. Abdominal Breathing • Results from lowering of diaphragm: Phrenic nerve • Necessary when: Infant Costal cartilages are calcified

31. Expiration • Mostly passive