Pulmonary Anatomy

Pulmonary Blood Supply

Two Arterial Blood Supplies

  • Bronchial Arteries: originate from aorta and intercostal arteries
    • Form plexus in the bronchial wall
    • Uncommonly affected by pulmonary vasculitis
  • Pulmonary Arteries: originate from RV
    • Pulmonary capillaries are located in the alveolar septa (where they participate in gas exchange)

Two Venous Drainage Systems

  • Bronchial Veins: uncommonly affected by pulmonary vasculitis
  • Pulmonary Veins: typically located in the intralobular septa

Respiratory Muscles

  • Diaphragm: innervated by C3–5
  • Inspiratory Accessory: external intercostals, scalene, and sternocleidomastoid muscles
  • Expiratory Accessory: internal intercostals and abdominal muscles


Definition of Airways

  • Conducting Airway: extends from the trachea to the terminal bronchioles
    • Functions to filter, humidify and heat air
  • Respiratory Airway: includes the respiratory bronchioles, alveolar ducts, and sacs
    • Site of gas exchange
  • Acinus: portion of lung supplied by a primary respiratory bronchiole

Cartilage Composition of Airways

  • Trachea: C-shaped cartilage with dorsal smooth muscle
  • Main Bronchi: semicircular cartilage
  • Bronchi: irregularly shaped cartilage plates
  • Bronchioles: no cartilage support, surrounded by muscular layer

Components of Alveolar-Capillary Surface

  • Surfactant
  • Alveolar Epithelium: type 1 and type 2 alveolar cells (the latter of which produces surfactant)
  • Interstitium
  • Endothelium

Influence of Particle Size on Airway Deposition

  • Particles 2–5 um in Size: reach small airways
  • Particles 5–10 um in Size: impact on the carina or main bronchi
  • Particles >10 um: stopped in the upper airways

Lobar Anatomy (Frontal View of CXR)



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