Chest Wall and Lung Anatomy and Physiology

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Chest Wall and LungAnatomy and Physiology

• Zeyad S Alharbi, M.D.

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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

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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

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Blood Supply and Innervation
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Anterior Chest Wall Deformities

• 1. Pectus excavatum
• 2. Pectus carinatum
• 3. Polands syndrome
• 4. Sternal defects
• 5. Miscellaneous

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Etiology and Incidence of Pectus Excavatum

• It is reported 1/700 of lives birth
• MF3.41
• 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

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M-S Abnormalities with Pectus Excavatum

• Scoliosis
• Kyphosis
• Myopathy
• Marfans syndrome
• Cerebral palsy
• Prune-belly syndrome
• Tuberous sclerosis

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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

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Pectus Carinatum( Pigeon Chest )

• It refers to anterior protrusion of the sternum
• It is less common than pectus excavatum

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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

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• (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

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Polands 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

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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
Patients arm is elevated
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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.
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Vascular Symptoms of TOS

• Subclavian Artery
• Prolonged compression trauma
• Intimal injury
• Stenosis, Thrombosis
• Post-stenotic Dilatation or Aneurysm
• Distal Micro-embolisation

• In Unilateral Raynauds always suspect TOS,
  because usually Raynauds phenomenon is systemic
  will cause bilateral symptoms

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Surgical Treatment of TOS

• Depending on the surgeons preference, there are
  2 approaches
• for the surgery
• Supraclavicular Approach
• Scalenectomy
• Excision of 1st rib fibrous bands
• Repair of subclavian artery if its 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

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The Respiratory Muscles
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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

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• 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.

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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

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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

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Lobes and Fissures
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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

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Lymphatics

• Lymphatic drainage follows vessels
• Parabronchial (peribronchial) lymphatics and
  nodes ? hilar nodes ? mediastinal nodes ? pre-
  and para-tracheal nodes ? supraclavicular nodes

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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

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Control of Breathing
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• 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

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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

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Regulation of Respiratory Center

• Cerebral Cortex
• Voluntary regulation of breathing
• Inflation Reflex
• Stretch receptors in walls of bronchi/bronchioles

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Respiratory Centers and Reflex Controls
Figure 23.27
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• Pulmonary function is affected by lung resection,
  extent varies
• pneumonectomy
• FEV1 3436?
• FVC 3640?
• VO2 max 2028?
• lobectomy
• FEV1 917?
• FVC 711?
• VO2 max 013?

Am J of Med (2005) 118, 578583
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Thank You!