Bronchus
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A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi (pronounced BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronchus. These are the widest bronchi, and enter the right lung, and the left lung at each hilum. The main bronchi branch into narrower secondary bronchi or lobar bronchi, and these branch into narrower tertiary bronchi or segmental bronchi. Further divisions of the segmental bronchi are known as 4th order, 5th order, and 6th order segmental bronchi, or grouped together as subsegmental bronchi.[1][2]The bronchi, when too narrow to be supported by cartilage, are known as bronchioles. No gas exchange takes place in the bronchi.
The trachea (windpipe) divides at the carina into two main or primary bronchi, the left bronchus and the right bronchus. The carina of the trachea is located at the level of the sternal angle and the fifth thoracic vertebra (at rest).
The cartilage and mucous membrane of the main bronchus (primary bronchi) are similar to those in the trachea. They are lined with respiratory epithelium, which is classified as ciliated pseudostratified columnar epithelium.[7] The epithelium in the main bronchi contains goblet cells, which are glandular, modified simple columnar epithelial cells that produce mucins, the main component of mucus. Mucus plays an important role in keeping the airways clear in the mucociliary clearance process.
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.[9] 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 resection is often curative.[10][11]
An accessory cardiac bronchus is usually an asymptomatic condition but may be associated with persistent infection or hemoptysis.[13][14] 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.
The left main bronchus departs from the trachea at a greater angle than that of the right main bronchus. The right bronchus is also wider than the left and these differences predispose the right lung to aspirational problems. If food, liquids, or foreign bodies are aspirated, they will tend to lodge in the right main bronchus. Bacterial pneumonia and aspiration pneumonia may result.
Cancer stage at diagnosis, which refers to extent of a cancer in the body, determines treatment options and has a strong influence on the length of survival. In general, if the cancer is found only in the part of the body where it started it is localized (sometimes referred to as stage 1). If it has spread to a different part of the body, the stage is regional or distant. The earlier lung and bronchus cancer is caught, the better chance a person has of surviving five years after being diagnosed. For lung and bronchus cancer, 18.9% are diagnosed at the local stage. The 5-year relative survival for localized lung and bronchus cancer is 61.2%.
CT bronchus sign. According to TSCT (0.5-mm reconstruction), we categorized the CT bronchus sign in each case into three types a to c according to the relationship between the nearest bronchus and the target lesion. In type A, the responsible bronchus clearly reached the inside of the target lesion. In type C, no bronchus could be detected in relation to the lesion. When the CT findings could be categorized into neither type A nor C, the CT bronchus sign was categorized as type B
CT bronchus sign and bronchoscopic diagnostic yield. The CT bronchus sign was a significant factor associated with a positive bronchoscopic diagnosis. In particular more than 90 % of malignant lesions with a CT bronchus sign type A could be diagnosed successfully. Conversely, in benign lesions, the bronchoscopic diagnostic yield was 0 % in lesions with a CT bronchus sign type C
Axial CT image This axial view is situated at the level of the tracheal bifurcation. The division of the distal trachea into the two main bronchi is already identifiable. The origin of the tracheal bronchus (TB) is shown.
Bronchoscopy The bronchoscopic image (Fig 2a) shows the origin of the tracheal bronchus (TB) nearly at the bifurcation. The proximal right main bronchus (RMB) is also visible. A view into the tracheal bronchus is provided by figure 2b. The orifice seems to be partially narrowed.
Frontal CT image The tracheal bifurcation is visible in this frontal view of the computed tomography of the chest. The origin of the tracheal bronchus is visible virtually at the carina (TB). The regular right upper lobe bronchus (RUB) itself is not displaced. There are no further recognizable abnormalities of the airways.
She underwent segmentectomy of the apical upper lobe segment. Upon operation we encountered the tracheal bronchus which led into the apical segment. The anatomy of the pulmonary artery as well as the venous drainage was normal. There were dense inflammatory adhesions between the tip of the right lung and the parietal pleura as an expression of the recurrent infections. The apical segment showed numerous nodules and calcifications. Frozen section was obtained to rule out pulmonary carcinoma.
Such congenital abnormalities are rarities. In the year 1962 Le Roux examined 1000 consecutive bronchograms, which had been obtained at the Regional Thoracic Unit in Edinburgh4. Altogether he encountered only 30 abnormalities of the right upper lobe bronchus. The most common disorder was an apical segmental bronchus originating from the trachea or the main bronchus. He found such a condition in 14 out of 1000 bronchograms4. Our patient had a displaced bronchus directing to the apical segment. The anatomy is clearly visible in the coronary CT images [Fig 1a+b].
Those congenital malformations are usually asymptomatic in adults whereas they are quite frequently associated with respiratory complications in paediatric patients. In a series comprising 18 infants with tracheal bronchus, resection of the right upper lobe due to recurrent pneumonia was eventually mandatory in five cases5. Persistent or recurrent pneumonia as well as the occurrence of bronchiectasis caused by a tracheal bronchus have also been reported in adults. Furthermore, pulmonary actinomycosis and haemoptysis have reportedly been associated with a tracheal bronchus3,6. Because of the rareness of the underlying condition the literature comprises mainly reports of single cases.
In our case, the tracheal bronchus was responsible for recurrent pneumonia with severe morphological changes of the lung parenchyma [Fig 1c]. The diagnosis was only established with considerable delay. Following segmentectomy the patient recuperated well. Henceforth she has been healthy and has shown no signs of pulmonary infections. This finding is in conformance with the results of the above mentioned paediatric series in which lobectomy led to resolution of the recurrent pneumonia, too. Similar outcome has been observed for surgical treatment of bronchiectasis in adults. Effective relief of symptoms is achievable by complete resection of all lung tissue with bronchiectatic destruction7,8. Segmentectomy of the lung is a safe procedure without a noteworthy loss of lung capacity. Hence, resection of the affected segment in case of a bronchial abnormality associated with pulmonary infections is justified and provides definite cure.
In conclusion, congenital abnormalities of the bronchi are rarities among the adult population and are mostly asymptomatic. Nevertheless, a tracheal bronchus can cause be associated with recurrent pulmonary infections and tumorlike inflammatory lesions. Then operative management by means of segmentectomy provides cure and simultaneously rules out lung cancer.
Displaced (B, C) and supernumerary (E, F) tracheal bronchi. They are determined based on the presence or absence of normal trifurcation of the RUL bronchus [9]. (A) Normal, (B) Displaced apical bronchus, (C) Displaced lobar bronchus, (D) Aberrant lobar bronchus, (E) Supernumerary apical bronchus, (F) Supernumerary lobar bronchus. Rt. br: right main stem bronchus, Lt. br: left main bronchus, Ant: anterior segment, Post: posterior segment, Apical: apical segment.
K.P.Y.H. was responsible for study design, coordination, analysis, interpretation of results, performed experiments and writing of the manuscript. J.C.W.H., M.-c.C., K.-c.N., R.H.H.C., K.-l.L. and T.T.K. performed experiments, analysis and interpretation of results. H.G. performed analysis and interpretation of sequencing results. K.-Y.S., M.K.Y.H. and T.W.K.A. provided human lung and bronchus tissue and read the manuscript. L.L.M.P. analysed and interpreted sequencing results and read the manuscript. M.P. analysed and interpreted results, and writing and revision of the manuscript. J.M.N. performed analysis, coordinated sample collection and interpreted results from immunohistochemical staining, and read the manuscript. M.C.W.C. was responsible for study design, overall coordination, interpretation of results and writing of the manuscript.
Your bronchi (BRAWN-kai) are the large tubes that connect to your trachea (windpipe) and direct the air you breathe to your right and left lungs. They are in your chest. Bronchi is the plural form of bronchus. The left bronchus carries air to your left lung. The right bronchus carries air to your right lung. Your bronchi are an essential part of your respiratory system. As you breathe and your lungs expand, your bronchi distribute the air within your lung.
Tracheal bronchus is an aberrant bronchus that arises most often from the right tracheal wall above the carina and is the result of an additional tracheal outgrowth early in embryonic life. Its incidence ranges between 0.1 and 5%. This anomaly usually is diagnosed incidentally during bronchoscopy or bronchography performed for various respiratory problems. Occasionally, it represents the underlying etiology for chronic pulmonary disease such as emphysema, atelectasis, and persistent or recurrent pneumonia, especially if it involves the right upper lobe and reflects an abnormal pulmonary clearing mechanism. Tracheal bronchus may be associated with other bronchopulmonary anomalies, tracheal stenosis, or Down's syndrome. In the absence of clinical symptoms, a diagnosis of tracheal bronchus does not require any treatment. In patients with recurrent right upper lobe disease and a tracheal bronchus, therapy should include resection of the aberrant bronchus as well as the lobe it supplies. 59ce067264
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