Segmental bronchi are the 'generation' of bronchi produced by the first division of the bronchial tree after the lobar bronchi. Hence, they are also the bronchi resulting from the second division of the bronchial tree after the tracheal bifurcation.
The territory supplied by one segmental bronchus defines the anatomical limits of a bronchopulmonary segment. Usually, there are ten segmental bronchi on both sides producing ten bronchopulmonary segments.
The segmental bronchi subdivide within each segment into subsegmental bronchi.