The lobar bronchus is the major airway within the respiratory tree that starts by division of the principal bronchi on both sides and ends at the point of its own subdivision into tertiary or segmental bronchi[GO]. [ http://en.wikipedia.org/wiki/Secondary_bronchus http://amigo.geneontology.org/amigo/term/GO:0060482 ]
Synonyms: secondary bronchus bronchi lobaris
- UMLS:C0225653 (ncithesaurus:Lobar_Bronchus)
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.