Blood supply of the lungs


  • The pulmonary arteries distribute deoxygenated blood to the lungs for aeration.

  • The pulmonary veins drain oxygenated blood from the lungs to the left atrium of the heart.

  • The bronchial arteries supply the substance of the lung with oxygenated blood.

    +) The two left bronchial arteries arise from the thoracic aorta .

    +) The single right bronchial artery arises from the first intercostal artery, or from the superior left bronchial artery.


  • The bronchial veins drain the lung tissue.

    +) The right bronchial vein drains into the azygous vein

    +) The left bronchial vein drains into the accessory hemiazygous vein or into the left superior intercostal vein.
 

Lymphatics of the lungs

There are two plexuses namely:

  • The superficial plexus, lying deep to the visceral pleura - bronchopulmonary lymph nodes.

  • The deep plexus, located in the submucosa of the bronchi, and in the peribronchial connective tissue- pulmonary thence to bronchopulmonary nodes

  • These drain into bronchomediastinal lymph trunks

  • These lymph trunks usually terminate on each side at the junction of the subclavian and internal jugular
    veins
    . The left trunk may terminate in the thoracic duct.
 

The relations of the lung

Mediastinal surface
Diaphragmatic surface
Costosternal surface
Posterior surface
Apex

  • Phrenic nerve,
  • Mediastinum and its contents
  • Liver on the right side,
  • Stomach and spleen on the left side.
  • The thoracic diaphragm intervenes.
  • ribs,
  • intercostal vessels and nerves;
  • sternum
  • internal thoracic vessels.
  • Upper thoracic vertebrae
  • Intervertebral discs.
  • Anteriorly to the 1 st rib and clavicle.

  • Medially it is related to the:

    - brachial plexus,
    - sympathetic chain,
    - trachea
    - esophagus
    - recurrent laryngeal nerve between them.


  • It is crossed by the subclavian artery and vein.
         
         
 

The bronchopulmonary segements

Definition

  • Portion of the lung aerated by a tertiary bronchus, together with its blood vessels, lymphatics, connective tissue and nerves.

  • The right lung bears 10 segments

  • The left has only 8 segments.
 

Characteristics of bronchopulmonary segments
  • Each segment is pyramidal in shape with its apex pointed towards the root of the lung and its base at the pleural surface.

  • Each segment is supplied by its own nerve, artery and vein.

  • Each segment is surrounded by connective tissue that is continous with the visceral pleura.


  • Each segment can be visualised independently during bronchoscopy

 

 

Chapter 28: The Chest Wall and Pleura