Editing Bronchus (section)

===Variation===
In 0.1 to 5% of people there is a right superior lobe bronchus arising from the main stem bronchus prior to the carina.  This is known as a '''tracheal bronchus''', and seen as an [[anatomical variation]].<ref name="Weerakkody">{{cite web |last1=Weerakkody |first1=Yuranga |title=Tracheal bronchus {{!}} Radiology Reference Article {{!}} Radiopaedia.org |url=https://radiopaedia.org/articles/tracheal-bronchus?lang=gb |website=Radiopaedia |access-date=21 November 2021}}</ref> It can have multiple variations and, although usually asymptomatic, it can be the root cause of pulmonary disease such as a recurrent infection. In such cases [[segmental resection|resection]] is often curative.<ref>{{Cite journal
| doi = 10.1503/cmaj.080280
| pmid = 19332762
| issn = 0820-3946
| volume = 180
| issue = 7
| pages = 783
| last = Shih
| first = Fu-Chieh |author2=Wei-Jing Lee |author3=Hung-Jung Lin
| title = Tracheal bronchus
| journal = Canadian Medical Association Journal
| date = 2009-03-31
| pmc = 2659830
}}
</ref>
<ref>
{{Cite journal
| doi = 10.1016/S0196-0709(87)80034-0
| pmid = 3592078
| issn = 0196-0709
| volume = 8
| issue = 2
| pages = 118–122
| last = Barat
| first = Michael
|author2=Horst R. Konrad
 | title = Tracheal bronchus
| journal = American Journal of Otolaryngology
| date = 1987-03-04
}}</ref>

The '''cardiac bronchus''' has a prevalence of ≈0.3% and presents as an accessory bronchus arising from the bronchus intermedius between the upper lobar bronchus and the origin of the middle and lower lobar bronchi of the right main bronchus.<ref>{{cite web |title=Cardiac bronchus |work=Radiopedia |url=http://radiopaedia.org/articles/cardiac-bronchus |archive-url=https://web.archive.org/web/20151115054026/http://radiopaedia.org/articles/cardiac-bronchus |archive-date=2015-11-15 |url-status=live }}</ref>

An accessory cardiac bronchus is usually an asymptomatic condition but may be associated with persistent infection or [[hemoptysis]].<ref>Parker MS, Christenson ML, Abbott GF. ''Teaching atlas of chest imaging.'' 2006, {{ISBN|3131390212}}</ref><ref>{{cite journal |vauthors=McGuinness G, Naidich DP, Garay SM, Davis AL, Boyd AD, Mizrachi HH |title=Accessory cardiac bronchus: CT features and clinical significance |journal=Radiology |volume=189 |issue=2 |pages=563–6 |year=1993 |pmid=8210391 |doi=10.1148/radiology.189.2.8210391 }}</ref> In about half of observed cases the cardiac bronchus presents as a short dead-ending bronchial stump, in the remainder the bronchus may exhibit branching and associated aerated [[lung parenchyma]].