1. Chest Wall and Lung Anatomy 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 Syndrome 1841
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. Scalenus Anterior Muscle
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. Vascular Symptoms of TOS
Subclavian Artery:
Prolonged compression & trauma
Intimal injury
Stenosis, Thrombosis
Post-stenotic Dilatation or Aneurysm
Distal Micro-embolisation
Band
Cervical Rib
{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 Cardiac Notch 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!