Anatomy of the Bronchial Tree

The branching airway divisions of the respiratory conducting and respiratory zones from the trachea down to the alveoli.

• Trachea: Cartilaginous windpipe that carries air from the larynx to the primary bronchi.
• Primary Bronchi: Right and left mainstem branches entering each lung at the hilum.
• Secondary Bronchi: Lobar branches delivering air directly to each anatomical lobe of the lungs.
• Tertiary Bronchi: Segmental branches that supply specific bronchopulmonary segments.
• Bronchioles: Narrow conducting tubes lacking cartilage plates and lined with smooth muscle.
• Terminal Bronchioles: The final branches of the conducting zone that direct air into the respiratory zone.
• Respiratory Bronchioles: Microscopic airways where limited gas exchange begins via sporadic outpouchings.
• Alveolar Ducts: Elongated airways lined with alveoli that lead into alveolar sacs.
• Alveolar Sacs: Terminal clusters of alveoli resembling bunches of grapes.
• Alveoli: Microscopic thin-walled air sacs where oxygen and carbon dioxide are exchanged with the blood.
• Epiglottis: Epiglottis
• Terminal bronchiole Respiratory / bronchioles: Terminal bronchiole Respiratory / bronchioles
• Larynx: Larynx
• Alveolar sac: Alveolar sac