Pulmonary Anatomy


Pulmonary Arterial Blood Supply

Lungs Have a Dual Arterial Blood Supply (Insights Imaging, 2020) [MEDLINE]

Pulmonary Arteries

  • Function
    • Pulmonary Arteries Predominantly Supply the Lung Parenchyma
  • Size/Pressure
    • Pulmonary Arteries are Larger Caliber than the Bronchial Arteries
    • Pulmonary Arteries are a Low-Pressure System
      • Consequently, Most Episodes of Hemoptysis Originate from the Pulmonary Arterial Circulation and are Not Life-Threatening
  • Anatomy
    • Pulmonary Arteries Originate from the Right Ventricle
  • Source of Hemoptysis (see Hemoptysis)
    • The Bronchial Arterial System is the Predominant Source of Hemoptysis in 90% of Cases of Massive Hemoptysis (Crit Care Med, 2000) [MEDLINE]
      • Other Sources Include
        • Pulmonary Arteries (5% of Cases)
        • Non-Bronchial Systemic Arteries (5% of Cases)

Bronchial Arteries

  • Function
    • Bronchial Arteries Predominantly Supply the Tracheobronchial Tree, Large Blood Vessels, Lymph Nodes, Esophagus, and Pleura (Radiographics, 2006) [MEDLINE]
      • The Bronchial Arterial Circulation Accounts for Only 2% of the Total Vascular Supply to the Lung
    • Bronchial Arteries are Very Plastic, Potentially Increasing Their Blood Flow from 1% to 30% of the Cardiac Output in Response to a Pulmonary Insult
      • Consequently, Bronchial Artery Hypertrophy and Dilatation of Thin-Walled Distal Bronchial-to-Pulmonary Artery Anastomoses May Occur
  • Size/Pressure
    • Bronchial Arteries Have a Smaller Caliber than the Pulmonary Arteries
      • On Contrast-Enhanced CT, They are Very Thin and Difficult to Detect
      • Normal Caliber of the Bronchial Arteries is <1.5 mm Near the Origin and <0.5 mm Distally, as They Branch in the Pulmonary Hila
      • When Bronchial Artery Hypertrophy Occurs, Their Diameter Can Exceed 2 mm, and They Tend to Have a More Tortuous Course
    • Bronchial Arteries are a High-Pressure System (Under Systemic Arterial Pressure)
  • Anatomy
    • Orthotopic Origin
      • The Bronchial Arteries Most Commonly Originate from the Descending Thoracic Aorta, Usually at the T5-T6 Vertebral Plane, 1–2 cm Above or Below the Level of the Carina
      • The Orthotopic Right Bronchial Artery Originates Preferentially from the Posteromedial Aortic Wall (Directly or or More Commonly from a Short Intercostal-Bronchial Trunk), Running Retrotracheally Towards the Hilum
      • The Orthotopic Left Bronchial Artery Originates Preferentially from the Anterior or Lateral Aortic Wall, Running Retrotracheally Towards the Hilum
      • Most Patients Have 1-2 Bronchial Arteries on Each Side and a Total of 3-4 Bronchial Arteries
    • Ectopic Origin
      • In Up to 36% of Cases, the Bronchial Arteries Ectopically Originate from Aortic Arch, Subclavian Artery, Thyrocervical Trunk, Internal Mammary Artery, or Coronary Arteries (J Thorac Imaging, 2003) [MEDLINE] (Eur Radiol, 2007) [MEDLINE]
        • Ectopic Bronchial Arteries are Recognized Due to Their Adjacent Course with the Associated Bronchi
    • Bronchial Arteries Have Distal Microvascular Anastomoses Connecting to the Pulmonary Arterial System (Chest, 1972) [MEDLINE]
  • Source of Hemoptysis
    • Despite the Bronchial Arteries Accounting for Only 2% of the Total Vascular Supply to the Lung, the Bronchial Arteries are the Predominant Source of Hemoptysis in 90% of Cases of Massive Hemoptysis (Crit Care Med, 2000) [MEDLINE]
      • Other Sources Include
        • Pulmonary Arteries (5% of Cases)
        • Non-Bronchial Systemic Arteries (5% of Cases)

Other Arteries

  • The Non-Bronchial Arterial Circulation (Aorta, Intercostal Arteries, Coronary Arteries, Thoracic Arteries, Axillary Arteries, Subclavian Arteries, Upper and Lower Inferior Phrenic Arteries) Can Supply the Lungs in <5% of Cases (Chest, 2008) [MEDLINE] (Respiration, 2010) [MEDLINE]
    • Many Chronic Inflammatory Lung Lesions are Jointly Supplied by Hypertrophied Bronchial Arteries, as Well as by Collateral Systemic Arteries

Pulmonary Venous Drainage

Respiratory Muscles

Airways

Definition of Airways

Cartilage Composition of Airways

Components of Alveolar-Capillary Surface

Influence of Particle Size on Airway Deposition

Lobar Anatomy (Frontal View of CXR)

PULM ANATOMY

Secondary Pulmonary Lobule

The Secondary Pulmonary Lobule is a Functional Unit of the Lung Surrounded by an Interlobular Septum (W.S. Miller [The lung. 2nd ed. Springfield, IL: Charles C Thomas, 1947]) (NEJM, 2020) [MEDLINE]

Ground-Glass Infiltrates Occur on the Chest CT Scan When Air within the Acini in the Pulmonary Lobule is Displaced by Any of the Following Four Mechanisms

References