Chest Wall and Lung Anatomy and Physiology

1. Chest Wall and LungAnatomy and Physiology Zeyad S Alharbi, M.D.

2. Anatomy and Physiology of the Thorax • Thoracic Skeleton • 12 Pair of C-shaped Ribs • Ribs 1-7: Join at sternum with cartilage end-points • Ribs 8-10: Join sternum with combined cartilage at 7th rib • Ribs 11-12: No anterior attachment • Sternum • Manubrium • Joins to clavicle and 1st rib • Jugular Notch • Body • Sternal angle (Angle of Louis) • Junction of the manubrium with the sternal body • Attachment of 2nd rib • Xiphoid Process • Distal portion of sternum

5. Anatomy and Physiology of the Thorax • Thoracic Skeleton • Topographical Thoracic Reference Lines • Midclavicular line • Anterior axillary line • Mid-axillary line • Posterior axillary line • Intercostal Space • Artery, Vein and Nerve on inferior margin of each rib • Thoracic Inlet • Superior opening of the thorax • Curvature of 1st rib with associated structures • Thoracic Outlet • Inferior opening of the thorax • 12th rib and associated structures & Xiphisternal joint

6. Blood Supply and Innervation

7. Anterior Chest Wall Deformities • 1. Pectus excavatum • 2. Pectus carinatum • 3. Poland’s syndrome • 4. Sternal defects • 5. Miscellaneous

8. Etiology and Incidence of Pectus Excavatum • It is reported 1/700 of lives birth • M:F=3.4:1 • 37% occur in Families with Chest wall deformities • It is a posterior depression of the sternum and costal cartilage due to over grow of costal cartilage • The 1st and 2nd ribs, manubrium are in normal position

9. M-S Abnormalities with Pectus Excavatum • Scoliosis • Kyphosis • Myopathy • Marfan’s syndrome • Cerebral palsy • Prune-belly syndrome • Tuberous sclerosis

11. Symptoms of Pectus Excavatum • Decreased exercise tolerance • Fatigability • Dyspnea on exertion, and sternal pain • Palpitations and multiple respiratory tract infections are reported • MOST complaint : cosmetic deformity rather than symptomatology

12. Pectus Carinatum( Pigeon Chest ) • It refers to anterior protrusion of the sternum • It is less common than pectus excavatum

13. Categories of Pectus Carinatum • 1. Chondrogladiolar (I) It is the most common pectus carinatum (II) It consists of anterior protrusion of the body of sternum and lower costal cartilages

14. (2) Lateral Pectus Carinatum : a unilateral protrusion of the costal cartilages and is usually accompanied by sternal rotation to the opposite side (3) Chondromanubrial: (I) Uncommon (II) Protrusion of Manubrium, 2nd and 3rd costal cartilages with relative depression of the body and sternum

16. Poland’s Syndrome1841 • It refers to a congenital absence of the pectoralis major and minor muscles, ribs, breast abnormality, chest wall depression and syndactyly, brachydactyly or absence of phalanges • It is present in 1/30000 • The etiology is unknown

18. Thoracic Outlet: • The space through which the subclavian artery, vein and brachial plexus pass to the upper limb • Symptoms develop when these structures are compressed at the outlet • Boundaries: First rib, clavicle and Scalene muscles Clavicle Scalenus Anterior Muscle 1st Rib Patient’s arm is elevated

19. Thoracic Outlet Syndrome “TOS” {Definition of cervical rib: an accessory rib which is not normally present. If present it may cause compression of important structures in the thoracic outlet. } Cervical Rib: 0.5-1% population (not all are symptomatic) • Neurogenic symptoms 95% • Ulnar nerve C8-T1 is usually affected • Vascular Symptoms 5% • Subclavian artery • Subclavian vein {cervical rib between the transverse process of C7 & the 1st rib. You can see the cervical rib in the other side elevating the brachial plexus.}

21. Band Cervical Rib Vascular Symptoms of TOS Subclavian Artery: Prolonged compression & trauma Intimal injury Stenosis, Thrombosis Post-stenotic Dilatation or Aneurysm Distal Micro-embolisation • {In Unilateral Raynaud’s always suspect TOS, because usually Raynaud’s phenomenon is systemic & will cause bilateral symptoms}

22. Surgical Treatment of TOS Depending on the surgeon’s preference, there are 2 approaches for the surgery: • Supraclavicular Approach: • Scalenectomy • Excision of 1st rib & fibrous bands • Repair of subclavian artery if it’s injured and patient has vascular problems: • Thrombectomy, patch angioplasty • Excision of aneurysm & bypass graft {scalenectomy & 1st rib excision are enough in those with neurological symptoms} • Transaxillary Approach: • Excision of 1st rib. This causes the brachial to go down a little relieving the compression

23. The Respiratory Muscles

25. Anatomy and Physiology of the Thorax Pleura: appears between the 4th and 7th gestational weeks • Visceral Pleura • Cover lungs • Parietal Pleura • Lines inside of thoracic cavity. • Pleural Space

26. The relationships of the pleural reflections and the lobes of the lung to the ribs that at the midclavicular line, the recess is between rib spaces 6 and 8, at the midaxillary line between 8 and 10 and at the paravertebral line between 10 and 12.

27. Lungs – Gross Anatomy • Paired, cone-shaped organs in thoracic cavity • Separated by heart and other mediastinal structures • Covered by pleura • Extend from diaphragm inferiorly to just above clavicles superiorly • Lies against thoracic cage (pleura, muscles, ribs) anteriorly, laterally and posteriorly

28. Lungs – Gross Anatomy • Hilum • Medial ‘root’ of the lung • Point at which vessels, airways and lymphatics enter and exit • Cardiac Notch • Lies in medial part of left lung to accommodate the heart

29. Lobes and Fissures

30. Lung – Blood Supply • Dual Supply • Bronchial Supply: arises from superior thoracic aorta or the aortic arch. • Supply bronchi, airway airway walls and pleura • Pulmonary Supply • Pulmonary arteries enter at hila and branch with airways

31. Lymphatics • Lymphatic drainage follows vessels • Parabronchial (peribronchial) lymphatics and nodes  hilar nodes  mediastinal nodes  pre- and para-tracheal nodes  supraclavicular nodes

32. Anatomy and Physiology of the Thorax • Mediastinum • Central space within thoracic cavity • Boundaries • Lateral: Lungs • Inferior: Diaphragm • Superior: Thoracic inlet • Structures • Heart • Great Vessels • Esophagus • Trachea • Nerves • Vagus • Phrenic • Thoracic Duct

34. Control of Breathing

35. Respiratory Center in Reticular Formation of the Brain Stem • Medullary Rhythmicity Center • Controls basic rhythm of respiration • Inspiratory (predominantly active) and expiratory (usually inactive in quiet respiration) neurones • Drives muscles of respiration • Pneumotaxic Area • Inhibits inspiratory area • Apneustic Area • Stimulates inspiratory area, prolonging inspiration

36. Regulation of Respiratory Center • Chemical Regulation • Most important • Central and peripheral chemoreceptors • Most important factor is CO2 (and pH) •  in arterial CO2 causes  in acidity of cerebrospinal fluid (CSF) •  in CSF acidity is detected by pH sensors in medulla • Medulla  rate and depth of breathing

37. Regulation of Respiratory Center • Cerebral Cortex • Voluntary regulation of breathing • Inflation Reflex • Stretch receptors in walls of bronchi/bronchioles

38. Respiratory Centers and Reflex Controls Figure 23.27

39. Pulmonary function is affected by lung resection, extent varies: • pneumonectomy: • FEV1: 34~36%↓ • FVC: 36~40%↓ • VO2 max: 20~28%↓ • lobectomy: • FEV1: 9~17%↓ • FVC: 7~11%↓ • VO2 max: 0~13%↓ Am J of Med (2005) 118, 578–583

40. Thank You!