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The lung hilum is the medial surface of each lung where the bronchi, pulmonary vessels, lymphatics, and nerves enter and exit the lung, forming the root of the lung. It is an anatomically, radiologically, and clinically important region frequently assessed in chest imaging.

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Anatomy

Boundaries & Location

• Located on the mediastinal surface of both lungs.
• Each hilum is formed by the structures of the lung root, which pass through a reflection of pleura known as the pulmonary ligament.

Contents of the Lung Hilum

1. Bronchi (main, lobar, segmental).
2. Pulmonary arteries.
3. Pulmonary veins (superior & inferior).
4. Bronchial arteries & veins.
5. Lymph nodes and lymphatic vessels.
6. Autonomic nerves (pulmonary plexus).

Arrangement (Right vs Left)

• Right hilum:
  • Bronchus lies superior to pulmonary artery (“eparterial bronchus”).
  • Pulmonary artery anterior to bronchus.
• Left hilum:
  • Pulmonary artery lies superior to bronchus.
  • (Mnemonic: RALS – Right Anterior, Left Superior for artery position relative to bronchus).

Epomedicine. Hilar arrangement in Lungs, Liver, Kidneys : Mnemonic | Epomedicine. Epomedicine. Published June 4, 2023. https://epomedicine.com/medical-students/hilar-arrangement-in-lungs-liver-kidneys-mnemonic/

Mediastinal Lung Anatomy - Medial View / rev.med

Radiology