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Secondary bronchus

Secondary bronchus
1. Trachea
2. Mainstem bronchus
3. Lobar bronchus
4. Segmental bronchus
5. Bronchiole
6. Alveolar duct
7. Alveolus
Front view of cartilages of larynx, trachea, and bronchi.
Latin bronchi lobares
Dorlands/Elsevier b_23/12198332

Secondary bronchi (also known as lobar bronchi) arise from the primary bronchi, with each one serving as the airway to a specific lobe of the lung.



They have relatively large lumens that are lined by respiratory epithelium. There is a smooth muscle layer below the epithelium arranged as two ribbons of muscle that spiral in opposite directions. This smooth muscle layer contains seromucous glands. Irregularly arranged plates of hyaline cartilage surround the smooth muscle. These plates give structural support to the bronchus and maintain the patency of the lumen.

Secondary bronchi of left lung

  • superior lobe bronchus
  • inferior lobe bronchus

Secondary bronchi of right lung

  • superior lobe bronchus (or eparterial bronchus)
  • middle lobe bronchus
  • inferior lobe bronchus

Additional images


  • Gartner, Leslie P. and James L. Hiatt. Color Atlas of Histology, 3rd ed. (2000). ISBN 0-7817-3509-2
  • Gartner, Leslie P. and James L. Hiatt. Color Textbook of Histology, 2nd ed. (2001). ISBN 0-7216-8806-3
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Secondary_bronchus". A list of authors is available in Wikipedia.
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