• Parts: Cartilaginous rings (anterior), Membranous wall (posterior), Carina
• Size: Length 10–12 cm; Diameter 20–25mm (coronal)
• Shape: Tubular; D-shaped or oval on cross-section
• Position: Midline; extends from cricoid cartilage (C6) to carina (T4/T5)
• Character: Fibrocartilaginous tube; 16–20 C-shaped rings
• Time: Derives from laryngotracheal groove (foregut) at week 4
• Connections:
  • Arterial: Inferior thyroid arteries; Bronchial arteries
  • Venous: Inferior thyroid veins
  • Lymphatics: Pretracheal and paratracheal nodes
  • Nerve: Vagus nerve; Recurrent laryngeal nerves

• Parts: Mainstem → Lobar (3 R, 2 L) → Segmental → Subsegmental
• Size: Tapers distally; Mainstem diam ~12-16mm
• Shape: Cylindrical branching tubes
• Position: Central → Peripheral distribution; Carina at T4-T5
• Character: Cartilage support decreases distally; smooth muscle increases
• Time: Branching morphogenesis (Wk 5-16)
• Connections:
  • Arterial: Bronchial arteries
  • Venous: Bronchial veins
  • Lymphatics: Hilar & mediastinal nodes
  • Nerve: Parasympathetic (Vagus) & Sympathetic (T2-T5)

Faces of Bronchi – Mainstem Disease

Faces of Encasement of the Proximal Airways

Cases of Bronchi Main Stem Diseases

• Parts: Bronchus, Pulmonary Artery, Bronchial Artery, Lymphatics, Nerves, Axial Connective Tissue
• Size: Tapers distally; walls should appear sharp
• Shape: Cylindrical branching cord
• Position: Axial distribution; runs from hilum to the center of the secondary lobule
• Character: The “strong” structural backbone of the lung (Axial fiber system)
• Time: Develops as airways and arteries branch together
• Connections:
  • Arterial: Pulmonary Artery (deoxygenated); Bronchial Artery (oxygenated)
  • Venous: Pulmonary veins run separately in septa (not in the bundle)
  • Lymphatics: Deep lymphatic system
  • Nerve: Pulmonary plexus

Faces of the Bronchovascular Bundle

Faces of Bronchovascular Opacities

Cases of Bronchovascular Bundle

• Parts: 10 Right Segments; 8-10 Left Segments
• Size: Variable wedge volumes
• Shape: Pyramidal/Wedge-shaped (Apex toward hilum)
• Position: Anatomically distinct units separated by septa
• Character: Functional unit with own bronchus and artery
• Time: Embryonic period development
• Connections:
  • Arterial: Segmental Pulmonary Artery
  • Venous: Pulmonary veins (Intersegmental)
  • Lymphatics: Peribronchial & Septal
  • Nerve: Autonomic plexus

• Parts: Centrilobular structures (bronchiole, artery); Septal structures (veins, lymph)
• Size: 1.0–2.5 cm diameter
• Shape: Polyhedral / Pyramidal
• Position: Peripheral lung parenchyma
• Character: Smallest lung unit surrounded by connective tissue
• Time: Post-natal alveolization
• Connections:
  • Arterial: Terminal arteriole (Center)
  • Venous: Pulmonary venule (Periphery)
  • Lymphatics: Interlobular septal lymphatics
  • Nerve: Fine autonomic fibers

• Parts: Axial (Bronchovascular), Parenchymal (Alveolar), Peripheral (Subpleural)
• Size: Microscopic to macroscopic septa
• Shape: Network / Scaffold
• Position: Throughout lung parenchyma
• Character: Connective tissue (Collagen/Elastin)
• Time: Develops with airway branching
• Connections:
  • Arterial: Supports vascular travel
  • Venous: Houses venous radicles
  • Lymphatics: Major route for lymphatic drainage
  • Nerve: N/A

• Parts: Visceral (lung surface), Parietal (chest wall), Pleural Space
• Size: Potential space (~10-20 mL fluid)
• Shape: Continuous serous sac
• Position: Envelops lungs; lines thoracic cavity
• Character: Mesothelial monolayer
• Time: Derived from Somatic (Parietal) and Splanchnic (Visceral) mesoderm
• Connections:
  • Arterial: Bronchial (Visc) / Intercostal (Par)
  • Venous: Pulmonary (Visc) / Systemic (Par)
  • Lymphatics: Stomata in parietal pleura (primary drainage)
  • Nerve: Phrenic/Intercostal (Parietal = Pain sensitive)

• Parts: Ribs, Intercostal muscles, Diaphragm
• Size: Variable thoracic volume
• Shape: Conical cage
• Position: Boundary of thoracic cavity
• Character: Musculoskeletal pump
• Time: Somite derivation
• Connections:
  • Arterial: Intercostal arteries
  • Venous: Azygos / Hemiazygos system
  • Lymphatics: Parasternal / Intercostal nodes
  • Nerve: Phrenic (Diaphragm); Intercostals (Ribs)

• Parts: MPA → RPA/LPA → Lobar → Segmental
• Size: MPA diam ~29mm; matches bronchus diameter at periphery
• Shape: Tubular, tapering
• Position: Run adjacent to bronchi (“Bronchoarterial bundle”)
• Character: Elastic (central) → Muscular (distal); Deoxygenated blood
• Time: 6th Aortic Arch derivative
• Connections:
  • Arterial: Vasa vasorum supply wall
  • Venous: N/A
  • Lymphatics: Perivascular lymphatics
  • Nerve: Autonomic regulation of vascular tone

• Parts: Right (usually 1 from Intercosto-bronchial trunk), Left (usually 2 from Aorta)
• Size: Small caliber (< 2mm)
• Shape: Tortuous, small vessels
• Position: Run along posterior wall of main bronchi
• Character: Systemic arterial supply (Oxygenated)
• Time: Develop to supply lung bud stroma
• Connections:
  • Arterial: Origin from Descending Aorta
  • Venous: Drain to Azygos/Hemiazygos (and some to Pulmonary Veins)
  • Lymphatics: N/A
  • Nerve: Autonomic

• Parts: 4 Main Veins (R/L Superior & Inferior)
• Size: Variable; generally larger than corresponding arteries
• Shape: Tubular
• Position: Run independent of airways (in interlobular septa)
• Character: Thin-walled; Oxygenated blood return
• Time: Incorporated into Left Atrium
• Connections:
  • Arterial: Vasa vasorum
  • Venous: Drain into Left Atrium
  • Lymphatics: Septal lymphatics
  • Nerve: Extensions of LA autonomic plexus

• Parts: Superficial (pleural) & Deep (peribronchovascular) networks
• Size: Microscopic capillaries to macroscopic ducts
• Shape: Network of channels and nodes
• Position: Along bronchovascular bundles and septa
• Character: Valved channels
• Time: Develop from venous system
• Connections:
  • Arterial: N/A
  • Venous: Ultimately drain to venous angle
  • Lymphatics: Hilar (N1) → Mediastinal (N2) nodes
  • Nerve: N/A

• Parts: Anterior and Posterior Pulmonary Plexus
• Size: N/A
• Shape: Network of fibers
• Position: Around root of lung and bronchial tree
• Character: Autonomic (Involuntary)
• Time: Neural crest migration
• Connections:
  • Arterial: Regulates vascular tone
  • Venous: N/A
  • Lymphatics: N/A
  • Nerve: Parasympathetic (Vagus); Sympathetic (T2-T5)