Bronchus

Bronchus

1. Bronchial Arteries

   • The bronchial arteries & veins constitute the 'nutritive' vascular system of the pulmonary tissues.
   • They interconnect within the lung with branches of the pulmonary arteries & veins.
   • The bronchial arteries originate from the thoracic aorta or one of its branches:
     • A single right bronchial artery normally arises from the third posterior intercostal artery (but occasionally, it originates from the upper left bronchial artery)
     • Two left bronchial arteries arise directly from the anterior surface of the aorta.

2. Bronchial Veins

   • The bronchial veins drain into:
     • Either the pulmonary veins or the left atrium
     • & Into the : azygos vein on the right or into the superior intercostal vein or hemiazygos vein on the left.

3. Intrapulmonary branches of the principle bronchi

   • The trachea gives 2 principal bronchi (right and left)
   • Each principal bronchus gives lobar bronchus then segmental bronchus.

4. Right Principal bronchus

   • 1) Before it enters the hilum, the right principle bronchus gives off the:
     • Superior lobar bronchi
     • Inferior lobar bronchi
   • 2) After entering the lung the inferior lobar bronchus divides into
     • Middle Lobar Bronchus
     • Lower Lobar Bronchus
   • 3) So it divides into 3 lobar bronchi to the 3 lobes of the lung
     • Superior lobe
     • Middle lobe
     • Inferior lobe
     • which then give off 10 segmental bronchi to the bronchopulmonary segments.
       • Superior lobar bronchus divides into 3 segmental bronchi:
         • Apical
         • Anterior
         • Posterior
       • Middle lobar bronchus divides into 2 segmental bronchi :
         • Medial
         • Lateral
       • Inferior lobar bronchus divides into :
         • apical
         • 4 basal segmental bronchi:
           • Anterior
           • Lateral
           • Medial
           • Basal

5. Left Principal Bronchus

   • 1) It has no branches outside the lung
   • 2) Inside the lung it divides into 2 lobar bronchi (superior and inferior) to the 2 lobes of the lung.
   • 3) The 2 lobar bronchi are then give off 10 segmental bronchi to the bronchopulmonary segments
     • Superior lobar bronchus divides into:
       • Upper Apical Segmental Bronchus
       • Anterior Segmental Bronchus
       • Posterior Segmental Bronchus
       • Superior Lingular Bronchus
       • Inferior Lingular Bronchus
     • Inferior Lobar Bronchus divides into:
       • Lower Lobe Apical Segmental bronchus
       • 4 Basal Segmental Bronchi
         • Anterior
         • Lateral
         • Medial
         • Posterior

6. Bronchopulmonary Segments

   • Is a functionally independent unit of lung tissue
   • Is the largest subdivision of a lobe
   • Is pyramid shaped, with the apex at the lung root
   • Receives its own segmental (tertiary) bronchus
   • Has separate arterial supply from other segments
   • Surrounded by connective tissue containing intersegmental vein which drain the segments
   • Can be removed surgically without affecting the function of other segments

7. Apical segment of the lower lobe

   • Is located alongside the base of the scapular spine (where you can listen to this segment).
   • Is the most dependent part of the lung when lying supine in bed and is the region where intrapulmonary fluid may collect in some conditions.