part of part of has part has part has_part overlaps overlaps proximally connected to system lobe of lung cartilage of bronchus lobar bronchus segmental bronchus VHOG:0001446 EHDAA:7049 EHDAA:7070 tertiary bronchus Wikipedia:Segmental_bronchus NCIT:C33526 UBERON:0002184 MA:0000439 SCTID:245513001 EHDAA:7058 EHDAA:7043 EHDAA:7064 The tertiary bronchi (also known as the segmental bronchi) arise from the secondary bronchi. The respiratory epithelium lining their lumen is surrounded by a layer of smooth muscle. This layer is composed of two ribbons of smooth muscle that spiral in opposite directions. The smooth muscle layer is surrounded by irregular plates of hyaline cartilage which help maintain the patency of the airway. Each of the tertiary bronchi serves a specific bronchopulmonary segment. There are 10 tertiary bronchi in the right lung, and eight in the left. The tertiary bronchi get smaller and divide into primary bronchioles. [WP,unvetted]. FMA:7407 bronchus smooth muscle lung mesenchyme intrapulmonary bronchus bronchus submucosal gland bronchopulmonary segment