Bronchial tree (subsegmental bronchi)

Arbor bronchialis

RespiratoryOrgansThoraxLeft and right

View left in 3D View right in 3D

What it is

The subsegmental bronchi and bronchioles branch repeatedly (about 23 generations in all) from each segmental bronchus into the lung tissue; four further generations are shown here.

Function

Distributes inspired air evenly through the lung and warms, humidifies and filters it on the way to the alveoli.

Size

Airways shrink from ~4 mm (subsegmental) to ~1 mm (bronchioles, which lack cartilage) and 0.5 mm (terminal bronchioles).

Clinical note

Bronchioles have no cartilage, so their smooth muscle can close them almost completely during an asthma attack.